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Thursday, October 6, 2022

Katyn massacre

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https://en.wikipedia.org/wiki/Katyn_massacre

Katyn massacre
Trzy krzyze.jpg
Katyn-Kharkov-Mednoye memorial in Świętokrzyskie Mountains, Poland

Katyn massacre is located in the Soviet Union
LocationKatyn Forest, Kalinin and Kharkiv prisons in Soviet Union
DateApril–May 1940
Attack type
Mass murder
Deaths22,000
VictimsPolish military officers and intelligentsia prisoners of war
PerpetratorsSoviet Union (NKVD)
Map of the sites related to the Katyn massacre
Map of the sites related to the Katyn massacre

The Katyn massacre was a series of mass executions of nearly 22,000 Polish military officers and intelligentsia prisoners of war carried out by the Soviet Union, specifically the NKVD ("People's Commissariat for Internal Affairs", the Soviet secret police) in April and May 1940. Though the killings also occurred in the Kalinin and Kharkiv prisons and elsewhere, the massacre is named after the Katyn Forest, where some of the mass graves were first discovered by German forces.

The massacre was initiated in NKVD chief Lavrentiy Beria's proposal to Joseph Stalin to execute all captive members of the Polish officer corps, which was secretly approved by the Soviet Politburo led by Stalin. Of the total killed, about 8,000 were officers imprisoned during the 1939 Soviet invasion of Poland, another 6,000 were police officers, and the remaining 8,000 were Polish intelligentsia the Soviets deemed to be "intelligence agents and gendarmes, spies and saboteurs, former landowners, factory owners and officials". The Polish Army officer class was representative of the multi-ethnic Polish state; the murdered included ethnic Poles, Ukrainians, Belarusians, and Jews including the chief Rabbi of the Polish Army, Baruch Steinberg.

The government of Nazi Germany announced the discovery of mass graves in the Katyn Forest in April 1943. Stalin severed diplomatic relations with the London-based Polish government-in-exile when it asked for an investigation by the International Committee of the Red Cross. After the Vistula–Oder offensive where the mass graves fell into Soviet control, the Soviet Union claimed the Nazis had killed the victims, and it continued to deny responsibility for the massacres until 1990, when it officially acknowledged and condemned the killings by the NKVD, as well as the subsequent cover-up by the Soviet government.

An investigation conducted by the office of the prosecutors general of the Soviet Union (1990–1991) and the Russian Federation (1991–2004) confirmed Soviet responsibility for the massacres, but refused to classify this action as a war crime or as an act of mass murder. The investigation was closed on the grounds that the perpetrators were dead, and since the Russian government would not classify the dead as victims of the Great Purge, formal posthumous rehabilitation was deemed inapplicable. In November 2010, the Russian State Duma approved a declaration blaming Stalin and other Soviet officials for ordering the massacre.

The falsified Soviet version of the events has become known as the "Katyn lie", a term coined in reference to the "Auschwitz lie".

Background

Invasion of Poland

Refer to Caption
Soviet Foreign Minister Vyacheslav Molotov signs the Molotov–Ribbentrop Pact. Behind him: 
Ribbentrop and Stalin.

On 1 September 1939, the invasion of Poland by Nazi Germany began. Consequently, Britain and France, fulfilling the Anglo-Polish and Franco-Polish treaties of alliance, declared war on Germany. Despite these declarations of war, the two nations undertook minimal military activity during what became known as the Phoney War.

The Soviet invasion of Poland began on 17 September, in accordance with the Molotov–Ribbentrop Pact. The Red Army advanced quickly and met little resistance, as Polish forces facing them were under orders not to engage the Soviets. About 250,000 to 454,700 Polish soldiers and policemen were captured and interned by the Soviet authorities. Some were freed or escaped quickly, but 125,000 were imprisoned in camps run by the NKVD. Of these, 42,400 soldiers, mostly of Ukrainian and Belarusian ethnicity serving in the Polish Army, who lived in the territories of Poland annexed by the Soviet Union, were released in October. The 43,000 soldiers born in western Poland, then under Nazi control, were transferred to the Germans; in turn, the Soviets received 13,575 Polish prisoners from the Germans.

Polish prisoners of war

Soviet repressions of Polish citizens occurred as well over this period. Since Poland's conscription system required every nonexempt university graduate to become a military reserve officer, the NKVD was able to round up a significant portion of the Polish educated class as prisoners of war. According to estimates by the Institute of National Remembrance (IPN), roughly 320,000 Polish citizens were deported to the Soviet Union (this figure is questioned by some other historians, who hold to older estimates of about 700,000–1,000,000). IPN estimates the number of Polish citizens who died under Soviet rule during World War II at 150,000 (a revision of older estimates of up to 500,000). Of the group of 12,000 Poles sent to Dalstroy camp (near Kolyma) in 1940–1941, mostly POWs, only 583 men survived; they were released in 1942 to join the Polish Armed Forces in the East. According to Tadeusz Piotrowski, "during the war and after 1944, 570,387 Polish citizens had been subjected to some form of Soviet political repression". As early as 19 September, the head of the NKVD, Lavrentiy Beria, ordered the secret police to create the Main Administration for Affairs of Prisoners of War and Internees to manage Polish prisoners. The NKVD took custody of Polish prisoners from the Red Army, and proceeded to organise a network of reception centres and transit camps, and to arrange rail transport to prisoner-of-war camps in the western USSR. The largest camps were at Kozelsk (Optina Monastery), Ostashkov (Stolobny Island on Lake Seliger near Ostashkov), and Starobelsk. Other camps were at Jukhnovo (rail station Babynino), Yuzhe (Talitsy), rail station Tyotkino (90 kilometres (56 mi) from Putyvl), Kozelshchyna, Oranki, Vologda (rail station Zaonikeevo), and Gryazovets.

A large group of Polish Prisoners of War
Polish POWs captured by the Red Army during the Soviet invasion of Poland

Kozelsk and Starobelsk were used mainly for military officers, while Ostashkov was used mainly for Polish Scouting, gendarmes, police officers, and prison officers. Some prisoners were members of other groups of Polish intelligentsia, such as priests, landowners, and law personnel. The approximate distribution of men throughout the camps was as follows: Kozelsk, 5000; Ostashkov, 6570; and Starobelsk, 4000. They totalled 15,570 men.

According to a report from 19 November 1939, the NKVD had about 40,000 Polish POWs: 8,000–8,500 officers and warrant officers, 6,000–6,500 officers of police, and 25,000 soldiers and non-commissioned officers who were still being held as POWs. In December, a wave of arrests resulted in the imprisonment of additional Polish officers. Ivan Serov reported to Lavrentiy Beria on 3 December that "in all, 1,057 former officers of the Polish Army had been arrested". The 25,000 soldiers and non-commissioned officers were assigned to forced labor (road construction, heavy metallurgy).

Preparations

Once at the camps, from October 1939 to February 1940, the Poles were subjected to lengthy interrogations and constant political agitation by NKVD officers, such as Vasily Zarubin. The prisoners assumed they would be released soon, but the interviews were in effect a selection process to determine who would live and who would die. According to NKVD reports, if a prisoner could not be induced to adopt a pro-Soviet attitude, he was declared a "hardened and uncompromising enemy of Soviet authority".

On 5 March 1940, pursuant to a note to Joseph Stalin from Beria, six members of the Soviet PolitburoStalin, Vyacheslav Molotov, Lazar Kaganovich, Kliment Voroshilov, Anastas Mikoyan, and Mikhail Kalinin — signed an order to execute 25,700 Polish "nationalists and counterrevolutionaries" kept at camps and prisons in occupied western Ukraine and Belarus. The reason for the massacre, according to the historian Gerhard Weinberg, was that Stalin wanted to deprive a potential future Polish military of a large portion of its talent. The Soviet leadership, and Stalin in particular, viewed the Polish prisoners as a "problem" as they might resist being under Soviet rule. Therefore, they decided the prisoners inside the "special camps" were to be shot as "avowed enemies of Soviet authority".

Executions

Letter in Cyrillic, dated March 5, 1940, contents per caption
Memo from Beria to Stalin, proposing the execution of Polish officers

The number of victims is estimated at 22,000, with a lower limit of confirmed dead of 21,768. According to Soviet documents declassified in 1990, 21,857 Polish internees and prisoners were executed after 3 April 1940: 14,552 prisoners of war (most or all of them from the three camps) and 7,305 prisoners in western parts of the Byelorussian and Ukrainian SSRs. Of them 4,421 were from Kozelsk, 3,820 from Starobelsk, 6,311 from Ostashkov, and 7,305 from Byelorussian and Ukrainian prisons. The head of the NKVD Administration for Affairs of Prisoners of War and Internees, Pyotr Soprunenko [ru], was involved in "selections" of Polish officers to be executed at Katyn and elsewhere.

Those who died at Katyn included soldiers (an admiral, two generals, 24 colonels, 79 lieutenant colonels, 258 majors, 654 captains, 17 naval captains, 85 privates, 3,420 non-commissioned officers, and seven chaplains), 200 pilots, government representatives and royalty (a prince, 43 officials), and civilians (three landowners, 131 refugees, 20 university professors, 300 physicians; several hundred lawyers, engineers, and teachers; and more than 100 writers and journalists). In all, the NKVD executed almost half the Polish officer corps. Altogether, during the massacre, the NKVD executed 14 Polish generals: Leon Billewicz (ret.), Bronisław Bohatyrewicz (ret.), Xawery Czernicki (admiral), Stanisław Haller (ret.), Aleksander Kowalewski [pl], Henryk Minkiewicz (ret.), Kazimierz Orlik-Łukoski, Konstanty Plisowski (ret.), Rudolf Prich (killed in Lviv), Franciszek Sikorski (ret.), Leonard Skierski (ret.), Piotr Skuratowicz, Mieczysław Smorawiński, and Alojzy Wir-Konas (promoted posthumously). Not all of the executed were ethnic Poles, because the Second Polish Republic was a multiethnic state, and its officer corps included Belarusians, Ukrainians, and Jews. It is estimated about 8% of the Katyn massacre victims were Polish Jews. 395 prisoners were spared from the slaughter, among them Stanisław Swianiewicz and Józef Czapski. They were taken to the Yukhnov camp or Pavlishtchev Bor and then to Gryazovets. Up to 99% of the remaining prisoners were killed. People from the Kozelsk camp were executed in Katyn Forest; people from the Starobelsk camp were killed in the inner NKVD prison of Kharkiv and the bodies were buried near the village of Piatykhatky; and police officers from the Ostashkov camp were killed in the internal NKVD prison of Kalinin (Tver) and buried in Mednoye. All three burial sites had already been secret cemeteries of the victims of the Great Purge of 1937–1938. Later, recreational areas of NKVD/KGB were established there.

Aerial view of the Katyn massacre grave
 
Photo from 1943 exhumation of mass grave of Polish officers killed by NKVD in Katyń Forest
 
A mass grave, with multiple corpses visible
A mass grave at Katyn, 1943

Detailed information on the executions in the Kalinin NKVD prison was provided during a hearing by Dmitry Tokarev, former head of the Board of the District NKVD in Kalinin. According to Tokarev, the shooting started in the evening and ended at dawn. The first transport, on 4 April 1940, carried 390 people, and the executioners had difficulty killing so many people in one night. The following transports held no more than 250 people. The executions were usually performed with German-made .25 ACP Walther Model 2 pistols supplied by Moscow, but Soviet-made 7.62×38mmR Nagant M1895 revolvers were also used. The executioners used German weapons rather than the standard Soviet revolvers, as the latter were said to offer too much recoil, which made shooting painful after the first dozen executions. Vasily Mikhailovich Blokhin, chief executioner for the NKVD, is reported to have personally shot and killed 7,000 of the condemned, some as young as 18, from the Ostashkov camp at Kalinin prison, over 28 days in April 1940.

After the condemned individual's personal information was checked and approved, he was handcuffed and led to a cell insulated with stacks of sandbags along the walls, and a heavy, felt-lined door. The victim was told to kneel in the middle of the cell, and was then approached from behind by the executioner and immediately shot in the back of the head or neck. The body was carried out through the opposite door and laid in one of the five or six waiting trucks, whereupon the next condemned was taken inside and subjected to the same treatment. In addition to muffling by the rough insulation in the execution cell, the pistol gunshots were masked by the operation of loud machines (perhaps fans) throughout the night. Some post-1991 revelations suggest prisoners were also executed in the same manner at the NKVD headquarters in Smolensk, though judging by the way the corpses were stacked, some captives may have been shot while standing on the edge of the mass graves. This procedure went on every night, except for the public May Day holiday.

Some 3,000 to 4,000 Polish inmates of Ukrainian prisons and those from Belarus prisons were probably buried in Bykivnia and in Kurapaty respectively, about 50 women including two sisters, Klara Auerbach-Margules and Stella Menkes, among them. Lieutenant Janina Lewandowska, daughter of Gen. Józef Dowbor-Muśnicki, was the only woman POW executed during the massacre at Katyn.

Discovery

17 men, most in military uniform, stand in a cemetery, inspecting two graves.
Secretary of State of the Vichy regime Fernand de Brinon and others in Katyn at the graves of Mieczysław Smorawiński and Bronisław Bohatyrewicz, April 1943

The question about the fate of the Polish prisoners was raised soon after Operation Barbarossa began in June 1941. The Polish government-in-exile and the Soviet government signed the Sikorski–Mayski agreement, which announced the willingness of both to fight together against Nazi Germany and for a Polish army to be formed on Soviet territory. The Polish general Władysław Anders began organizing this army, and soon he requested information about the missing Polish officers. During a personal meeting, Stalin assured him and Władysław Sikorski, the Polish Prime Minister, all the Poles were freed, and not all could be accounted because the Soviets "lost track" of them in Manchuria. Józef Czapski investigated the fate of Polish officers between 1941 and 1942.

In 1942, with the territory around Smolensk under German occupation, captive Polish railroad workers heard from the locals about a mass grave of Polish soldiers at Kozelsk near Katyn; finding one of the graves, they reported it to the Polish Underground State. The discovery was not seen as important, as nobody thought the discovered grave could contain so many victims. In early 1943, Rudolf Christoph Freiherr von Gersdorff, a German officer serving as the intelligence liaison between the Wehrmacht's Army Group Centre and Abwehr, received reports about mass graves of Polish military officers. These reports stated the graves were in the forest of Goat Hill near Katyn. He passed the reports to his superiors (sources vary on when exactly the Germans became aware of the graves—from "late 1942" to January–February 1943, and when the German top decision makers in Berlin received those reports [as early as 1 March or as late as 4 April]). Joseph Goebbels saw this discovery as an excellent tool to drive a wedge between Poland, the Western Allies, and the Soviet Union, and reinforcement for the Nazi propaganda line about the horrors of Bolshevism, and American and British subservience to it. After extensive preparation, on 13 April, Reichssender Berlin broadcast to the world that German military forces in the Katyn forest near Smolensk had uncovered a ditch that was "28 metres long and 16 metres wide [92 ft by 52 ft], in which the bodies of 3,000 Polish officers were piled up in 12 layers". The broadcast went on to charge the Soviets with carrying out the massacre in 1940.

Refer to caption
Polish banknotes and epaulets recovered from mass graves

The Germans brought in a European Red Cross committee called the Katyn Commission, comprising 12 forensic experts and their staff, from Belgium, Bulgaria, Croatia, Denmark, Finland, France, Hungary, Italy, the Netherlands, Romania, Switzerland, and Bohemia & Moravia. The Germans were so intent on proving the Soviets were behind the massacre they even included some Allied prisoners of war, among them writer Ferdynand Goetel, the Polish Home Army prisoner from Pawiak. After the war, Goetel escaped with a fake passport due to an arrest warrant issued against him. Jan Emil Skiwski was a collaborator. Józef Mackiewicz has published several texts about the crime. Two of the 12, the Bulgarian Marko Markov and the Czech František Hájek, with their countries becoming satellite states of the Soviet Union, were forced to recant their evidence, defending the Soviets and blaming the Germans. The Croatian pathologist Eduard Miloslavić managed to escape to the US. The Katyn massacre was beneficial to Nazi Germany, which used it to discredit the Soviet Union. On 14 April 1943, Goebbels wrote in his diary: "We are now using the discovery of 12,000 Polish officers, killed by the GPU, for anti-Bolshevik propaganda on a grand style. We sent neutral journalists and Polish intellectuals to the spot where they were found. Their reports now reaching us from ahead are gruesome. The Führer has also given permission for us to hand out a drastic news item to the German press. I gave instructions to make the widest possible use of the propaganda material. We shall be able to live on it for a couple of weeks".

The decomposing remains of Katyn victims, found in a mass grave.
Katyn exhumation, 1943

The Soviet government immediately denied the German charges. They claimed the Polish prisoners of war had been engaged in construction work west of Smolensk, and consequently were captured and executed by invading German units in August 1941. The Soviet response on 15 April to the initial German broadcast of 13 April, prepared by the Soviet Information Bureau, stated "Polish prisoners-of-war who in 1941 were engaged in construction work west of Smolensk and who...fell into the hands of the German-Fascist hangmen". In April 1943, the Polish government-in-exile led by Sikorski insisted on bringing the matter to the negotiation table with the Soviets and on opening an investigation by the International Red Cross. Stalin, in response, accused the Polish government of collaborating with Nazi Germany and broke off diplomatic relations with it. The Soviet Union also started a campaign to get the Western Allies to recognize the pro-Soviet government-in-exile of the Union of Polish Patriots led by Wanda Wasilewska. Sikorski died in the 1943 Gibraltar B-24 crash —an event convenient for the Allied leaders.

Soviet actions

When Joseph Goebbels was informed in September 1943 that the German Army had to withdraw from the Katyn area, he wrote a prediction in his diary. His entry for 29 September 1943 reads: "Unfortunately, we have had to give up Katyn. The Bolsheviks undoubtedly will soon 'find' that we shot 12,000 Polish officers. That episode is one that is going to cause us quite a little trouble in the future. The Soviets are undoubtedly going to make it their business to discover as many mass-graves as possible and then blame it on us".

Having retaken the Katyn area almost immediately after the Red Army had recaptured Smolensk, around September–October 1943, NKVD forces began a cover-up operation. They destroyed a cemetery the Germans had permitted the Polish Red Cross to build and removed other evidence. Witnesses were "interviewed" and threatened with arrest for collaborating with the Nazis if their testimonies disagreed with the official line. As none of the documents found on the dead had dates later than April 1940, the Soviet secret police planted false evidence to place the apparent time of the massacre in mid-1941, when the German military had controlled the area. NKVD operatives Vsevolod Merkulov and Sergei Kruglov issued a preliminary report, dated 10–11 January 1944, that concluded the Polish officers were shot by German soldiers.

In January 1944, the Soviet Extraordinary State Commission for ascertaining and investigating crimes perpetrated by the German-Fascist invaders set up another commission, the Special Commission for Determination and Investigation of the Shooting of Polish Prisoners of War by German-Fascist Invaders in Katyn Forest [pl] (Специальная комиссия по установлению и расследованию обстоятельств расстрела немецко-фашистскими захватчиками в Катынском лесу (близ Смоленска) военнопленных польских офицеров). The commission's name implied a predestined conclusion. It was headed by Nikolai Burdenko, the president of the USSR Academy of Medical Sciences, hence the commission is often known as the "Burdenko Commission", who was appointed by Moscow to investigate the incident. Its members included prominent Soviet figures such as the writer Aleksey Nikolayevich Tolstoy, but no foreign personnel were allowed to join the commission. The Burdenko Commission exhumed the bodies, rejected the 1943 German findings the Poles were shot by the Soviet army, assigned the guilt to the Nazis, and concluded all the shootings were done by German occupation forces in late 1941. It is uncertain how many members of the commission were misled by the falsified reports and evidence, and how many actually suspected the truth. Cienciala and Materski note the commission had no choice but to issue findings in line with the Merkulov-Kruglov report, and Burdenko was likely aware of the cover-up. He reportedly admitted something like that to friends and family shortly before his death in 1946. The Burdenko Commission's conclusions would be consistently cited by Soviet sources until the official admission of guilt by the Soviet government on 13 April 1990.

In January 1944, the Soviets also invited a group of more than a dozen mostly American and British journalists, accompanied by Kathleen Harriman, the daughter of the new American Ambassador W. Averell Harriman, and John F. Melby, third secretary at the American embassy in Moscow, to Katyn. Some regarded the inclusion of Melby and Harriman as a Soviet attempt to lend official weight to their propaganda. Melby's report noted the deficiencies in the Soviet case: problematic witnesses; attempts to discourage questioning of the witnesses; statements of the witnesses obviously being given as a result of rote memorization; and that "the show was put on for the benefit of the correspondents." Nevertheless, Melby, at the time, felt on balance the Soviet case was convincing. Harriman's report reached the same conclusion and after the war both were asked to explain why their conclusions seemed to be at odds with their findings, with the suspicion the conclusions were what the State Department wanted to hear. The journalists were less impressed and not convinced by the staged Soviet demonstration.

An example of Soviet propaganda spread by some Western Communists is Alter Brody's monograph Behind the Polish-Soviet Break (with an introduction by Corliss Lamont).

Western response

Eight soldiers in World War II-era uniforms, as per caption
British, Canadian, and American officers (POWs) brought by the Germans to view the exhumations

The growing Polish-Soviet tension was beginning to strain Western-Soviet relations at a time when the Poles' importance to the Allies, significant in the first years of the war, was beginning to fade, due to the entry into the conflict of the military and industrial giants, the Soviet Union and the United States. In retrospective review of records, both British Prime Minister Winston Churchill and U.S. President Franklin D. Roosevelt were increasingly torn between their commitments to their Polish ally and the demands by Stalin and his diplomats.

According to the Polish diplomat Edward Bernard Raczyński, Raczyński and General Sikorski met privately with Churchill and Alexander Cadogan on 15 April 1943, and told them the Poles had proof the Soviets were responsible for the massacre. Raczyński reports Churchill, "without committing himself, showed by his manner that he had no doubt of it". Churchill said "The Bolsheviks can be very cruel". On 17 April 1943 the Polish government issued a statement on this issue, asking for a Red Cross investigation, which was rejected by Stalin, who used the fact that Germans also requested such an investigation as a "proof" of Polish-German conspiracy, and which led to a deterioration of Polish-Soviet relations. Shortly afterward, however, on 24 April 1943, the British government successfully pressured the Poles to withdraw the request for a Red Cross investigation, and Churchill assured Stalin's regime: "We shall certainly oppose vigorously any 'investigation' by the International Red Cross or any other body in any territory under German authority. Such an investigation would be a fraud and its conclusions reached by terrorism". Unofficial or classified UK documents concluded Soviet guilt was a "near certainty", but the alliance with the Soviets was deemed to be more important than moral issues; thus the official version supported the Soviets, up to censoring any contradictory accounts. Churchill asked Owen O'Malley to investigate the issue, but in a note to the Foreign Secretary he noted: "All this is merely to ascertain the facts, because we should none of us ever speak a word about it." O'Malley pointed out several inconsistencies and near impossibilities in the Soviet version. Later, Churchill sent a copy of the report to Roosevelt on 13 August 1943. The report deconstructed the Soviet account of the massacre and alluded to the political consequences within a strongly moral framework but recognized there was no viable alternative to the existing policy. No comment by Roosevelt on the O'Malley report has been found. Churchill's own post-war account of the Katyn affair gives little further insight. In his memoirs, he refers to the 1944 Soviet inquiry into the massacre, which found the Germans responsible, and adds, "belief seems an act of faith".

Lt. Col. John H. Van Vliet Jr communication on Katyn

At the beginning of 1944, Ron Jeffery, an agent of British and Polish intelligence in occupied Poland, eluded the Abwehr and travelled to London with a report from Poland to the British government. His efforts were at first highly regarded, but subsequently ignored, which a disillusioned Jeffery later attributed to the actions of Kim Philby and other high-ranking communist agents entrenched in the British government. Jeffery tried to inform the British government about the Katyn massacre, but was as a result released from the Army.

In 1947, the Polish Government in exile 1944–1946 report on Katyn was transmitted to Telford Taylor.

In the United States a similar line was taken, notwithstanding two official intelligence reports into the Katyn massacre that contradicted the official position. In 1944, Roosevelt assigned his special emissary to the Balkans, Navy Lieutenant Commander George Earle, to produce a report on Katyn. Earle concluded the massacre was committed by the Soviet Union. Having consulted with Elmer Davis, director of the United States Office of War Information, Roosevelt rejected the conclusion (officially), declared he was convinced of Nazi Germany's responsibility, and ordered that Earle's report be suppressed. When Earle requested permission to publish his findings, the President issued a written order to desist. Earle was reassigned and spent the rest of the war in American Samoa.

A further report in 1945, supporting the same conclusion, was produced and stifled. In 1943, the Germans took two U.S. POWs—Capt. Donald B. Stewart and Col. John H. Van Vliet [de]—to Katyn for an international news conference. Documents released by the National Archives and Records Administration in September 2012 revealed Stewart and Van Vliet sent coded messages to their American superiors indicating they saw proof that implicated the Soviets. Three lines of evidence were cited. Firstly, the Polish corpses were in such an advanced state of decay that the Nazis could not have killed them, as they had only taken over the area in 1941. Secondly, none of the numerous Polish artifacts, such as letters, diaries, photographs and identification tags pulled from the graves, were dated later than the spring of 1940. Most incriminating was the relatively good state of the men's uniforms and boots, which showed they had not lived long after being captured. Later, in 1945, Van Vliet submitted a report concluding the Soviets were responsible for the massacre. His superior, Major General Clayton Lawrence Bissell, General George Marshall's assistant chief of staff for intelligence, destroyed the report. Washington kept the information secret, presumably to appease Stalin and not distract from the war against the Nazis. During the 1951–52 Congressional investigation into Katyn, Bissell defended his action before the United States Congress, arguing it was not in the U.S. interest to antagonize an ally (the USSR) whose assistance the nation needed against the Empire of Japan. In 1950, Van Vliet recreated his wartime report. In 2014, a copy of a report Van Vliet made in France during 1945 was discovered.

Post-war trials

From 28 December 1945 to 4 January 1946, a Soviet military court in Leningrad tried seven Wehrmacht servicemen. One of them, Arno Dürre, who was charged with murdering numerous civilians using machine-guns in Soviet villages, confessed to having taken part in the burial (though not the execution) of 15,000 to 20,000 Polish POWs in Katyn. For this he was spared execution and was given 15 years of hard labor. His confession was full of absurdities, and thus he was not used as a Soviet prosecution witness during the Nuremberg trials. He later recanted his confession, claiming the investigators forced him to confess.

At the London conference that drew up the indictments of German war crimes before the Nuremberg trials, the Soviet negotiators put forward the allegation, "In September 1941, 925 Polish officers who were prisoners of war were killed in the Katyn Forest near Smolensk". The U.S. negotiators agreed to include it, but were "embarrassed" by the inclusion (noting the allegation had been debated extensively in the press) and concluded it would be up to the Soviets to sustain it. At the trials in 1946, Soviet General Roman Rudenko raised the indictment, stating "one of the most important criminal acts for which the major war criminals are responsible was the mass execution of Polish prisoners of war shot in the Katyn forest near Smolensk by the German fascist invaders", but failed to make the case and the U.S. and British judges dismissed the charges. Only 70 years later did it become known that former OSS chief William Donovan had succeeded in getting the American delegation in Nuremberg to block the Katyn indictment. A German officer, Fabian von Schlabrendorff, who was stationed in Smolensk during the war, had convinced Donovan that not the Germans but the Soviets were the perpetrators. It was not the purpose of the court to determine whether Germany or the Soviet Union was responsible for the crime, but rather to attribute the crime to at least one of the defendants, which the court was unable to do.

1950s

In 1951 and 1952, with the Korean War as a background, a congressional investigation chaired by Rep. Ray Madden and known as the Madden Committee investigated the Katyn massacre. According to the Committee conclusion: "the Katyn massacre involved some 4,243 of the 15,400 Polish Army officers and intellectual leaders who were captured by the Soviets when Russia invaded Poland in September 1939." The committee concluded that these 4,243 Poles had been killed by the NKVD and that a case should be brought to the International Court of Justice. However, the question of responsibility remained controversial in the West as well as behind the Iron Curtain. In the United Kingdom in the late 1970s, plans for a memorial to the victims bearing the date 1940 (rather than 1941) were condemned as provocative in the political climate of the Cold War. It has also been alleged that the choice made in 1969 for the location of the Byelorussian Soviet Socialist Republic war memorial at the former Belarusian village named Khatyn, the site of the 1943 Khatyn massacre, was made to cause confusion with Katyn. The two names are similar or identical in many languages, and were often confused.

In Poland, the pro-Soviet authorities following the Soviet occupation after the war covered up the matter in accordance with the official Soviet propaganda line, deliberately censoring any sources that might provide information about the crime. Katyn was a forbidden topic in post-war Poland. Censorship in the Polish People's Republic was a massive undertaking and Katyn was specifically mentioned in the "Black Book of Censorship" used by the authorities to control the media and academia. Not only did government censorship suppress all references to it, but even mentioning the atrocity was dangerous. In the late 1970s, democracy groups like the Workers' Defence Committee and the Flying University defied the censorship and discussed the massacre, in the face of arrests, beatings, detentions, and ostracism. In 1981, Polish trade union Solidarity erected a memorial with the simple inscription "Katyn, 1940". It was confiscated by the police and replaced with an official monument with the inscription: "To the Polish soldiers—victims of Hitlerite fascism—reposing in the soil of Katyn". Nevertheless, every year on the day of Zaduszki, similar memorial crosses were erected at Powązki Cemetery and numerous other places in Poland, only to be dismantled by the police. Katyn remained a political taboo in the Polish People's Republic until the fall of the Eastern Bloc in 1989.

In the Soviet Union during the 1950s, the head of KGB, Alexander Shelepin, proposed and carried out the destruction of many documents related to the Katyn massacre to minimize the chance the truth would be revealed. His 3 March 1959 note to Nikita Khrushchev, with information about the execution of 21,857 Poles and with the proposal to destroy their personal files, became one of the documents that was preserved and eventually made public.

Revelations

A low stone wall, curving upward. Three statues of Polish soldiers are mounted at its center. Below the statues, Text is mounted as per caption.
Monument in Katowice, Poland, memorializing "Katyn, Kharkiv, Mednoye and other places of killing in the former USSR in 1940"

During the 1980s, there was increasing pressure on both the Polish and Soviet governments to release documents related to the massacre. Polish academics tried to include Katyn in the agenda of the 1987 joint Polish-Soviet commission to investigate censored episodes of the Polish-Russian history. In 1989, Soviet scholars revealed Joseph Stalin had indeed ordered the massacre, and in 1990 Mikhail Gorbachev admitted the NKVD had executed the Poles and confirmed two other burial sites similar to the site at Katyn: Mednoye and Piatykhatky.

On 30 October 1989, Gorbachev allowed a delegation of several hundred Poles, organized by the Polish association Families of Katyń Victims, to visit the Katyn memorial. This group included former U.S. national security advisor Zbigniew Brzezinski. A mass was held and banners hailing the Solidarity movement were laid. One mourner affixed a sign reading "NKVD" on the memorial, covering the word "Nazis" in the inscription such that it read "In memory of Polish officers killed by the NKVD in 1941." Several visitors scaled the fence of a nearby KGB compound and left burning candles on the grounds. Brzezinski commented:

It isn't a personal pain which has brought me here, as is the case in the majority of these people, but rather recognition of the symbolic nature of Katyń. Russians and Poles, tortured to death, lie here together. It seems very important to me that the truth should be spoken about what took place, for only with the truth can the new Soviet leadership distance itself from the crimes of Stalin and the NKVD. Only the truth can serve as the basis of true friendship between the Soviet and the Polish peoples. The truth will make a path for itself. I am convinced of this by the very fact that I was able to travel here.

His remarks were given extensive coverage on Soviet television. On 13 April 1990, the forty-seventh anniversary of the discovery of the mass graves, the USSR formally expressed "profound regret" and admitted Soviet secret police responsibility. The day was declared a worldwide Katyn Memorial Day (Polish: Światowy Dzień Pamięci Ofiar Katynia).

Post-communist investigations

In 1990, future Russian President Boris Yeltsin released the top-secret documents from the sealed "Package №1." and transferred them to the new Polish president Lech Wałęsa. Among the documents was a proposal by Lavrentiy Beria, dated 5 March 1940, to execute 25,700 Poles from Kozelsk, Ostashkov and Starobelsk camps, and from certain prisons of Western Ukraine and Belarus, signed by Stalin (among others). Another document transferred to the Poles was Aleksandr Shelepin's 3 March 1959 note to Nikita Khrushchev, with information about the execution of 21,857 Poles, as well as a proposal to destroy their personal files to reduce the possibility documents related to the massacre would be uncovered later. The revelations were also publicized in the Russian press, where they were interpreted as being one outcome of an ongoing power struggle between Yeltsin and Gorbachev.

Criminal prosecution attempts and further testimonies

In 1991, the Chief Military Prosecutor for the Soviet Union began proceedings against Pyotr Karpovich Soprunenko (b. 1908) for his role in the Katyn killings, but eventually declined to prosecute because Soprunenko was 83, almost blind, and recovering from a cancer operation. During his April 1991 interrogation, Soprunenko defended himself by denying his own signature. Soprunenko, who died in June 1992, was an NKVD captain in early 1940 and was the organization's Head of Directorate for Prisoners of War Affairs & Internees, from September 1939 to February 1943. In this capacity, he was reportedly involved in the planning and operational control of the executions, in following with Beria's and Merkulov's orders.

Further testimonies emerged in October 1991 via a report made by Nicholas Bethell, a British historian and Conservative member of the European Parliament, who obtained videotaped copies of the interrogations to surviving participants, statements, and met with military prosecutors in Moscow. His report mentioned Soprunenko and another participant, Vladimir Tokaryev, who was 89 but still recalled how 250 Poles were murdered every night in Kalinin. Bethell's report, which was published in The Observer, also quoted Tokaryev as saying that he learned of the massacre's plan in March 1940; he was called to a meeting in Moscow with Bogdan Kobulov, Beria's NKVD deputy, and claimed that Soprunenko was present in said meeting, in which the latter explained details of the operation. Moreover, Bethell's spoke of Soprunenko telling that he received an order from the Politburo to carry out the executions, signed by Stalin. Bethell also characterized Soprunenko as ″evasive and shifty″ in his deposition, showing little regret for his role.

A number of candles are arranged in a cross shape in a roadway, while a crowd of people look on.
Ceremony of military upgrading of Katyn massacre victims, Piłsudski Square, Warsaw, 10 November 2007

Later events

During Kwaśniewski's visit to Russia in September 2004, Russian officials announced they were willing to transfer all the information on the Katyn massacre to the Polish authorities as soon as it became declassified. In March 2005 the Prosecutor-General's Office of the Russian Federation concluded a decade-long investigation of the massacre and announced that the investigation was able to confirm the deaths of 1,803 out of 14,542 Polish citizens who had been sentenced to death while in three Soviet camps. He did not address the fate of about 7,000 victims who had not been in POW camps, but in prisons. Savenkov declared the massacre was not a genocide, that Soviet officials who had been found guilty of the crime were dead and that, consequently, "there is absolutely no basis to talk about this in judicial terms". Of the 183 volumes of files gathered during the Russian investigation, 116 were declared to contain state secrets and were classified.

On 22 March 2005, the Polish Sejm unanimously passed an act requesting the Russian archives to be declassified. The Sejm also requested Russia to classify the Katyn massacre as a crime of genocide. The resolution stressed that the authorities of Russia "seek to diminish the burden of this crime by refusing to acknowledge it was genocide and refuse to give access to the records of the investigation into the issue, making it difficult to determine the whole truth about the killing and its perpetrators."

In 2007, a case (Janowiec and Others v. Russia) was brought in front of the European Court of Human Rights, with the families of several victimes claiming that Russia violated the European Convention on Human Rights by withholding documents from the public. The declared admissible two complaints from relatives of the massacre victims against Russia regarding adequacy of the official investigation. In a ruling on 16 April 2012, the court found Russia had violated the rights of victims' relatives by not providing them with sufficient information about the investigation and described the massacre as a "war crime". But it also refused to judge the effectiveness of the Soviet Russian investigation because the related events took place before Russia ratified the Human Rights Convention in 1998. The plaintiffs filed an appeal but a 21 October 2013 ruling essentially reaffirmed the prior one, claiming that the matter is outside the court's competence, and only rebuking the Russian side for its failure to substantiate adequately why some critical information remained classified. In late 2007 and early 2008, several Russian newspapers, including Rossiyskaya Gazeta, Komsomolskaya Pravda, and Nezavisimaya Gazeta, printed stories that implicated the Nazis in the crime, spurring concern this was done with the tacit approval of the Kremlin. As a result, the Polish Institute of National Remembrance decided to open its own investigation.

In 2008, the Polish Foreign Ministry asked the government of Russia about alleged footage of the massacre filmed by the NKVD during the killings, something the Russians have denied exists. Polish officials believe this footage, as well as further documents showing cooperation of Soviets with the Gestapo during the operations, are the reason for Russia's decision to classify most of the documents about the massacre.

In the following years, 81 volumes of the case were declassified and transferred to the Polish government. As of 2012, 35 out of 183 volumes of files remain classified.

In June 2008, Russian courts consented to hear a case about the declassification of documents about Katyn and the judicial rehabilitation of the victims. In an interview with a Polish newspaper, Vladimir Putin called Katyn a "political crime".

In September 2009, Yevgeny Dzhugashvili, Stalin's grandson, sued Russian newspaper Novaya Gazeta after it published an article claiming his grandfather personally signed execution orders against civilians. Dzhugashvili centered his case on the veracity of a document showing Stalin ordered the Katyn massacre. On 13 October 2009, the Russian court rejected the suit.

On 21 April 2010, the Russian Supreme Court ordered the Moscow City Court to hear an appeal in an ongoing Katyn legal case. A civil rights group, Memorial, said the ruling could lead to a court decision to open up secret documents providing details about the killings of thousands of Polish officers. Russia handed over to Poland copies of 137 of the 183 volumes of unclassified material of Russian investigation of the Katyn criminal case. Russian President Dmitry Medvedev handed one of the volumes to the acting Polish president, Bronislaw Komorowski. Medvedev and Komorowski agreed the two states should continue to try to reveal the truth about the tragedy. The Russian president reiterated Russia would continue to declassify documents on the Katyn massacre and ordered to release the documents proving the guilt of Stalin and his secret police chief Beria. The acting Polish president said Russia's move might lay a good foundation for improving bilateral relations. In November 2010, the Russian State Duma issued an official declaration that condemned Joseph Stalin for Katyn massacres.

Archive searches are continuing in the Belarus state archives for the "Belarusian Katyn List" expected to contain the names of 3,870 officers whose identities and exact place of execution (presumably Bykivnia and Kuropaty, as mentioned above) were not yet established.

Legacy

Polish–Russian relations

Russian President Dmitry Medvedev and Polish President Bronislaw Komorowski laying wreaths at the Katyn massacre memorial complex, 11 April 2011

Russia and Poland remained divided on the legal description of the Katyn crime. The Poles considered it a case of genocide and demanded further investigations, as well as complete disclosure of Soviet documents.

In June 1998, Boris Yeltsin and Aleksander Kwaśniewski agreed to construct memorial complexes at Katyn and Mednoye, the two NKVD execution sites on Russian soil. In September of that year, the Russians also raised the issue of Soviet prisoner of war deaths in the camps for Russian prisoners and internees in Poland (1919–24). About 16,000 to 20,000 POWs died in those camps due to communicable diseases. Some Russian officials argued it was "a genocide comparable to Katyn". A similar claim was raised in 1994; such attempts are seen by some, particularly in Poland, as a highly provocative Russian attempt to create an "anti-Katyn" and "balance the historical equation". The fate of Polish prisoners and internees in Soviet Russia remains poorly researched.

On 4 February 2010, the Prime Minister of Russia, Vladimir Putin, invited his Polish counterpart, Donald Tusk, to attend a Katyn memorial service in April. The visit took place on 7 April 2010, when Tusk and Putin together commemorated the 70th anniversary of the massacre. Before the visit, the 2007 film Katyń was shown on Russian state television for the first time. The Moscow Times commented that the film's premiere in Russia was likely a result of Putin's intervention.

On 10 April 2010, an aircraft carrying Polish President Lech Kaczyński with his wife and 87 other politicians and high-ranking army officers crashed in Smolensk, killing all 96 aboard the aircraft. The passengers were to attend a ceremony marking the 70th anniversary of the Katyn massacre. The Polish nation was stunned; Prime Minister Donald Tusk, who was not on the plane, referred to the crash as "the most tragic Polish event since the war." In the aftermath, a number of conspiracy theories began to circulate. The catastrophe has also had major echoes in the international and particularly the Russian press, prompting a rebroadcast of Katyń on Russian television. The Polish President was to deliver a speech at the formal commemorations. The speech was to honour the victims, highlight the significance of the massacres in the context of post-war communist political history, as well as stress the need for Polish–Russian relations to focus on reconciliation. Although the speech was never delivered, it has been published with a narration in the original Polish and a translation has also been made available in English.

In November 2010, the State Duma (lower house of the Russian parliament) passed a resolution declaring long-classified documents "showed that the Katyn crime was carried out on direct orders of Stalin and other Soviet officials". The declaration also called for the massacre to be investigated further to confirm the list of victims. Members of the Duma from the Communist Party denied the Soviet Union had been to blame for the Katyn massacre and voted against the declaration. On 6 December 2010, Russian President Dmitry Medvedev expressed commitment to uncovering the whole truth about the massacre, stating "Russia has recently taken a number of unprecedented steps towards clearing up the legacy of the past. We will continue in this direction".

On 10 April 2022, in response to Polish authorities attempts to demolish or remove "post-Soviet occupation monuments", pro-government activists in support of the invasion parked heavy machinery with flags of the Russian Federation and letters Z outside the Katyn Memorial Cemetery, which was interpreted as an act of intimidation. This was denied by the organizers, who stated they wished to draw attention to the "Russophobic Polish authorities". A number of Russian politicians advocated to demolish Polish part of the memorial complex. Among them State Duma deputies Anatoly Wasserman and Alexey Chepa. On 28 June 2022 Leningradsky Court of Kaliningrad forbade distribution of the book "Katyn. On the trail of a crime". According to the court the book "rehabilitated Nazism" and "violated the law on glorifying Soviet Victory in the Great Patriotic War".

Those adopting pre-1990 views

The Communist Party of the Russian Federation and a number of other pro-Soviet Russian politicians and commentators claim that the story of Soviet guilt is a conspiracy and that the documents released in 1990 were forgeries. They insist that the original version of events, assigning guilt to the Nazis, is the correct version, and they call on the Russian government to start a new investigation that would revise the findings of 2004.

A number of Russian historians and organizations such as Memorial openly admit Soviet responsibility. In particular, they point to inconsistencies in this alternative version, namely the details of another contemporary mass execution site at Mednoye in the Tver Region. That part of Central Russia, they stress, was never under German occupation and yet it contained the remains of victims originating from the same camps as those killed in Katyn; the victims at Mednoye were also killed in April–May 1940. Mednoye was only examined in the 1990s and was found to contain well-preserved Polish uniforms, documents, souvenirs, and Soviet newspapers dating back to 1940.

In 2021, however, the Russian Ministry of Culture downgraded the memorial complex at Katyn on its Register of Sites of Cultural Heritage from a place of federal to one of only regional importance. Such decisions, says the preface to the site, are made in consultation with the regional authorities, i.e. the Smolensk Region administration. More important, the Ministry altered the descriptive text to say, once more, that the "Polish officers were shot by the Hitlerites in 1941".

In June 2022, Russia removed the Polish flag from the memorial complex, amidst a rise in Russia–Poland political tension due to the 2022 Russian invasion of Ukraine.

Plant perception (physiology)

From Wikipedia, the free encyclopedia

The leaf closing after touch in Mimosa pudica depends on electrical signals

Plant perception is the ability of plants to sense and respond to the environment by adjusting their morphology and physiology. Botanical research has revealed that plants are capable of reacting to a broad range of stimuli, including chemicals, gravity, light, moisture, infections, temperature, oxygen and carbon dioxide concentrations, parasite infestation, disease, physical disruption, sound, and touch. The scientific study of plant perception is informed by numerous disciplines, such as plant physiology, ecology, and molecular biology.

Aspects of perception

Light

The sunflower, a common heliotropic plant which perceives and reacts to sunlight by slow turning movement

Many plant organs contain photoreceptors (phototropins, cryptochromes, and phytochromes), each of which reacts very specifically to certain wavelengths of light. These light sensors tell the plant if it is day or night, how long the day is, how much light is available, and where the light is coming from. Shoots generally grow towards light, while roots grow away from it, responses known as phototropism and skototropism, respectively. They are brought about by light-sensitive pigments like phototropins and phytochromes and the plant hormone auxin.

Many plants exhibit certain behaviors at specific times of the day; for example, flowers that open only in the mornings. Plants keep track of the time of day with a circadian clock. This internal clock is synchronized with solar time every day using sunlight, temperature, and other cues, similar to the biological clocks present in other organisms. The internal clock coupled with the ability to perceive light also allows plants to measure the time of the day and so determine the season of the year. This is how many plants know when to flower (see photoperiodism). The seeds of many plants sprout only after they are exposed to light. This response is carried out by phytochrome signalling. Plants are also able to sense the quality of light and respond appropriately. For example, in low light conditions, plants produce more photosynthetic pigments. If the light is very bright or if the levels of harmful ultraviolet radiation increase, plants produce more of their protective pigments that act as sunscreens.

Gravity

To orient themselves correctly, plants must be able to sense the direction of gravity. The subsequent response is known as gravitropism.

In roots, gravity is sensed and translated in the root tip, which then grows by elongating in the direction of gravity. In shoots, growth occurs in the opposite direction, a phenomenon known as negative gravitropism. Poplar stems can detect reorientation and inclination (equilibrioception) through gravitropism.

Vine (Vitis) tendril. Note how the plant reaches for and wraps around the galvanised wire provided for the purpose. This is a very tough twig and appears to have no other purpose than support for the plant. Nothing else grows from it. It must reach out softly, then wrap around and then dry and toughen. See more at thigmotropism.

At the root tip, amyloplasts containing starch granules fall in the direction of gravity. This weight activates secondary receptors, which signal to the plant the direction of the gravitational pull. After this occurs, auxin is redistributed through polar auxin transport and differential growth towards gravity begins. In the shoots, auxin redistribution occurs in a way to produce differential growth away from gravity.

For perception to occur, the plant often must be able to sense, perceive, and translate the direction of gravity. Without gravity, proper orientation will not occur and the plant will not effectively grow. The root will not be able to uptake nutrients or water, and the shoot will not grow towards the sky to maximize photosynthesis.

Touch

All plants are able to sense touch. Thigmotropism is directional movement that occurs in plants responding to physical touch. Climbing plants, such as tomatoes, exhibit thigmotropism, allowing them to curl around objects. These responses are generally slow (on the order of multiple hours), and can best be observed with time-lapse cinematography, but rapid movements can occur as well. For example, the so-called "sensitive plant" (Mimosa pudica) responds to even the slightest physical touch by quickly folding its thin pinnate leaves such that they point downwards, and carnivorous plants such as the Venus flytrap (Dionaea muscipula) produce specialized leaf structures that snap shut when touched or landed upon by insects. In the Venus flytrap, touch is detected by cilia lining the inside of the specialized leaves, which generate an action potential that stimulates motor cells and causes movement to occur.

Smell

Wounded or infected plants produce distinctive volatile odors, (e.g. methyl jasmonate, methyl salicylate, green leaf volatiles), which can in turn be perceived by neighboring plants. Plants detecting these sorts of volatile signals often respond by increasing their chemical defenses or and prepare for attack by producing chemicals which defend against insects or attract insect predators.

Vibration

Plants upregulate chemical defenses such as glucosinolate and anthocyanin in response to vibrations created during herbivory.

Signal transduction

Plant hormones and chemical signals

Plants systematically use hormonal signalling pathways to coordinate their development and morphology.

Plants produce several signal molecules usually associated with animal nervous systems, such as glutamate, GABA, acetylcholine, melatonin, and serotonin. They may also use ATP, NO, and ROS for signaling in similar ways as animals do.

Electrophysiology

Plants have a variety of methods of delivering electrical signals. The four commonly recognized propagation methods include action potentials (APs), variation potentials (VPs), local electric potentials (LEPs), and systemic potentials (SPs)

Although plant cells are not neurons, they can be electrically excitable and can display rapid electrical responses in the form of APs to environmental stimuli. APs allow for the movement of signaling ions and molecules from the pre-potential cell to the post-potential cell(s). These electrophysiological signals are constituted by gradient fluxes of ions such as H+, K+, Cl, Na+, and Ca2+ but it is also thought that other electrically charge ions such as Fe3+, Al3+, Mg2+, Zn2+, Mn2+, and Hg2+ may also play a role in downstream outputs. The maintenance of each ions electrochemical gradient is vital in the health of the cell in that if the cell would ever reach equilibrium with its environment, it is dead. This dead state can be due to a variety of reasons such as ion channel blocking or membrane puncturing.

These electrophysiological ions bind to receptors on the receiving cell causing downstream effects result from one or a combination of molecules present. This means of transferring information and activating physiological responses via a signaling molecule system has been found to be faster and more frequent in the presence of APs.

These action potentials can influence processes such as actin-based cytoplasmic streaming, plant organ movements, wound responses, respiration, photosynthesis, and flowering. These electrical responses can cause the synthesis of numerous organic molecules, including ones that act as neuroactive substances in other organisms such as calcium ions.

The ion flux across cells also influence the movement of other molecules and solutes. This changes the osmotic gradient of the cell, resulting in changes to turgor pressure in plant cells by water and solute flux across cell membranes. These variations are vital for nutrient uptake, growth, many types of movements (tropisms and nastic movements) among other basic plant physiology and behavior.(Higinbotham 1973; Scott 2008; Segal 2016).

Thus, plants achieve behavioural responses in environmental, communicative, and ecological contexts.

Signal perception

Plant behavior is mediated by phytochromes, kinins, hormones, antibiotic or other chemical release, changes of water and chemical transport, and other means.

Plants have many strategies to fight off pests. For example, they can produce a slew of different chemical toxins against predators and parasites or they can induce rapid cell death to prevent the spread of infectious agents. Plants can also respond to volatile signals produced by other plants. Jasmonate levels also increase rapidly in response to mechanical perturbations such as tendril coiling.

In plants, the mechanism responsible for adaptation is signal transduction. Adaptive responses include:

  • Active foraging for light and nutrients. They do this by changing their architecture, e.g. branch growth and direction, physiology, and phenotype.
  • Leaves and branches being positioned and oriented in response to a light source.
  • Detecting soil volume and adapting growth accordingly, independently of nutrient availability.
  • Defending against herbivores.

Plant intelligence

Plants do not have brains or neuronal networks like animals do; however, reactions within signalling pathways may provide a biochemical basis for learning and memory in addition to computation and basic problem solving. Controversially, the brain is used as a metaphor by some plant perception researchers to provide an integrated view of signalling.

Plants respond to environmental stimuli by movement and changes in morphology. They communicate while actively competing for resources. In addition, plants accurately compute their circumstances, use sophisticated cost–benefit analysis, and take tightly controlled actions to mitigate and control diverse environmental stressors. Plants are also capable of discriminating between positive and negative experiences and of learning by registering memories from their past experiences. Plants use this information to adapt their behaviour in order to survive present and future challenges of their environments.

Plant physiology studies the role of signalling to integrate data obtained at the genetic, biochemical, cellular, and physiological levels, in order to understand plant development and behaviour. The neurobiological view sees plants as information-processing organisms with rather complex processes of communication occurring throughout the individual plant. It studies how environmental information is gathered, processed, integrated, and shared (sensory plant biology) to enable these adaptive and coordinated responses (plant behaviour); and how sensory perceptions and behavioural events are 'remembered' in order to allow predictions of future activities upon the basis of past experiences. Plants, it is claimed by some plant physiologists, are as sophisticated in behaviour as animals, but this sophistication has been masked by the time scales of plants' responses to stimuli, which are typically many orders of magnitude slower than those of animals.

It has been argued that although plants are capable of adaptation, it should not be called intelligence per se, as plant neurobiologists rely primarily on metaphors and analogies to argue that complex responses in plants can only be produced by intelligence. "A bacterium can monitor its environment and instigate developmental processes appropriate to the prevailing circumstances, but is that intelligence? Such simple adaptation behaviour might be bacterial intelligence but is clearly not animal intelligence." However, plant intelligence fits a definition of intelligence proposed by David Stenhouse in a book about evolution and animal intelligence, in which he describes it as "adaptively variable behaviour during the lifetime of the individual". Critics of the concept have also argued that a plant cannot have goals once it is past the developmental stage of seedling because, as a modular organism, each module seeks its own survival goals and the resulting organism-level behavior is not centrally controlled. This view, however, necessarily accommodates the possibility that a tree is a collection of individually intelligent modules cooperating, competing, and influencing each other to determine behavior in a bottom-up fashion. The development into a larger organism whose modules must deal with different environmental conditions and challenges is not universal across plant species, however, as smaller organisms might be subject to the same conditions across their bodies, at least, when the below and aboveground parts are considered separately. Moreover, the claim that central control of development is completely absent from plants is readily falsified by apical dominance.

The Italian botanist Federico Delpino wrote on the idea of plant intelligence in 1867. Charles Darwin studied movement in plants and in 1880 published a book, The Power of Movement in Plants. Darwin concludes:

It is hardly an exaggeration to say that the tip of the radicle thus endowed [..] acts like the brain of one of the lower animals; the brain being situated within the anterior end of the body, receiving impressions from the sense-organs, and directing the several movements.

In 2020, Paco Calvo studied the dynamic of plant movements and investigated whether French beans deliberately aim for supporting structures. Calvo said: “We see these signatures of complex behaviour, the one and only difference being is that it’s not neural-based, as it is in humans. This isn’t just adaptive behaviour, it’s anticipatory, goal-directed, flexible behaviour.”

In philosophy, there are few studies of the implications of plant perception. Michael Marder put forth a phenomenology of plant life based on the physiology of plant perception. Paco Calvo Garzon offers a philosophical take on plant perception based on the cognitive sciences and the computational modeling of consciousness.

Comparison with neurobiology

Plant sensory and response systems have been compared to the neurobiological processes of animals. Plant neurobiology concerns mostly the sensory adaptive behaviour of plants and plant electrophysiology. Indian scientist J. C. Bose is credited as the first person to research and talk about the neurobiology of plants. Many plant scientists and neuroscientists, however, view the term "plant neurobiology" as a misnomer, because plants do not have neurons.

The ideas behind plant neurobiology were criticised in a 2007 article published in Trends in Plant Science by Amedeo Alpi and 35 other scientists, including such eminent plant biologists as Gerd Jürgens, Ben Scheres, and Chris Sommerville. The breadth of fields of plant science represented by these researchers reflects the fact that the vast majority of the plant science research community rejects plant neurobiology as a legitimate notion. Their main arguments are that:

  • "Plant neurobiology does not add to our understanding of plant physiology, plant cell biology or signaling".
  • "There is no evidence for structures such as neurons, synapses or a brain in plants".
  • The common occurrence of plasmodesmata in plants "poses a problem for signaling from an electrophysiological point of view", since extensive electrical coupling would preclude the need for any cell-to-cell transport of ‘neurotransmitter-like' compounds.

The authors call for an end to "superficial analogies and questionable extrapolations" if the concept of "plant neurobiology" is to benefit the research community. Several responses to this criticism have attempted to clarify that the term "plant neurobiology" is a metaphor and that metaphors have proved useful on previous occasions. Plant ecophysiology describes this phenomenon.

Parallels in other taxa

The concepts of plant perception, communication, and intelligence have parallels in other biological organisms for which such phenomena appear foreign to or incompatible with traditional understandings of biology, or have otherwise proven difficult to study or interpret. Similar mechanisms exist in bacterial cells, choanoflagellates, fungal hyphae, and sponges, among many other examples. All of these organisms, despite being devoid of a brain or nervous system, are capable of sensing their immediate and momentary environment and responding accordingly. In the case of unicellular life, the sensory pathways are even more primitive in the sense that they take place on the surface of a single cell, as opposed to within a network of many related cells.

Thermal runaway

From Wikipedia, the free encyclopedia
 
Diagram of thermal runaway

Thermal runaway describes a process that is accelerated by increased temperature, in turn releasing energy that further increases temperature. Thermal runaway occurs in situations where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result. It is a kind of uncontrolled positive feedback.

In chemistry (and chemical engineering), thermal runaway is associated with strongly exothermic reactions that are accelerated by temperature rise. In electrical engineering, thermal runaway is typically associated with increased current flow and power dissipation. Thermal runaway can occur in civil engineering, notably when the heat released by large amounts of curing concrete is not controlled. In astrophysics, runaway nuclear fusion reactions in stars can lead to nova and several types of supernova explosions, and also occur as a less dramatic event in the normal evolution of solar-mass stars, the "helium flash".

Some climate researchers have postulated that a global average temperature increase of 3–4 degrees Celsius above the preindustrial baseline could lead to a further unchecked increase in surface temperatures. For example, releases of methane, a greenhouse gas more potent than CO2, from wetlands, melting permafrost and continental margin seabed clathrate deposits could be subject to positive feedback.

Chemical engineering

Chemical reactions involving thermal runaway are also called thermal explosions in chemical engineering, or runaway reactions in organic chemistry. It is a process by which an exothermic reaction goes out of control: the reaction rate increases due to an increase in temperature, causing a further increase in temperature and hence a further rapid increase in the reaction rate. This has contributed to industrial chemical accidents, most notably the 1947 Texas City disaster from overheated ammonium nitrate in a ship's hold, and the 1976 explosion of zoalene, in a drier, at King's Lynn. Frank-Kamenetskii theory provides a simplified analytical model for thermal explosion. Chain branching is an additional positive feedback mechanism which may also cause temperature to skyrocket because of rapidly increasing reaction rate.

Chemical reactions are either endothermic or exothermic, as expressed by their change in enthalpy. Many reactions are highly exothermic, so many industrial-scale and oil refinery processes have some level of risk of thermal runaway. These include hydrocracking, hydrogenation, alkylation (SN2), oxidation, metalation and nucleophilic aromatic substitution. For example, oxidation of cyclohexane into cyclohexanol and cyclohexanone and ortho-xylene into phthalic anhydride have led to catastrophic explosions when reaction control failed.

Thermal runaway may result from unwanted exothermic side reaction(s) that begin at higher temperatures, following an initial accidental overheating of the reaction mixture. This scenario was behind the Seveso disaster, where thermal runaway heated a reaction to temperatures such that in addition to the intended 2,4,5-trichlorophenol, poisonous 2,3,7,8-tetrachlorodibenzo-p-dioxin was also produced, and was vented into the environment after the reactor's rupture disk burst.

Thermal runaway is most often caused by failure of the reactor vessel's cooling system. Failure of the mixer can result in localized heating, which initiates thermal runaway. Similarly, in flow reactors, localized insufficient mixing causes hotspots to form, wherein thermal runaway conditions occur, which causes violent blowouts of reactor contents and catalysts. Incorrect equipment component installation is also a common cause. Many chemical production facilities are designed with high-volume emergency venting, a measure to limit the extent of injury and property damage when such accidents occur.

At large scale, it is unsafe to "charge all reagents and mix", as is done in laboratory scale. This is because the amount of reaction scales with the cube of the size of the vessel (V ∝ r³), but the heat transfer area scales with the square of the size (A ∝ r²), so that the heat production-to-area ratio scales with the size (V/A ∝ r). Consequently, reactions that easily cool fast enough in the laboratory can dangerously self-heat at ton scale. In 2007, this kind of erroneous procedure caused an explosion of a 2,400 U.S. gallons (9,100 L)-reactor used to metalate methylcyclopentadiene with metallic sodium, causing the loss of four lives and parts of the reactor being flung 400 feet (120 m) away. Thus, industrial scale reactions prone to thermal runaway are preferably controlled by the addition of one reagent at a rate corresponding to the available cooling capacity.

Some laboratory reactions must be run under extreme cooling, because they are very prone to hazardous thermal runaway. For example, in Swern oxidation, the formation of sulfonium chloride must be performed in a cooled system (−30 °C), because at room temperature the reaction undergoes explosive thermal runaway.

Microwave heating

Microwaves are used for heating of various materials in cooking and various industrial processes. The rate of heating of the material depends on the energy absorption, which depends on the dielectric constant of the material. The dependence of dielectric constant on temperature varies for different materials; some materials display significant increase with increasing temperature. This behavior, when the material gets exposed to microwaves, leads to selective local overheating, as the warmer areas are better able to accept further energy than the colder areas—potentially dangerous especially for thermal insulators, where the heat exchange between the hot spots and the rest of the material is slow. These materials are called thermal runaway materials. This phenomenon occurs in some ceramics.

Electrical engineering

Some electronic components develop lower resistances or lower triggering voltages (for nonlinear resistances) as their internal temperature increases. If circuit conditions cause markedly increased current flow in these situations, increased power dissipation may raise the temperature further by Joule heating. A vicious circle or positive feedback effect of thermal runaway can cause failure, sometimes in a spectacular fashion (e.g. electrical explosion or fire). To prevent these hazards, well-designed electronic systems typically incorporate current limiting protection, such as thermal fuses, circuit breakers, or PTC current limiters.

To handle larger currents, circuit designers may connect multiple lower-capacity devices (e.g. transistors, diodes, or MOVs) in parallel. This technique can work well, but is susceptible to a phenomenon called current hogging, in which the current is not shared equally across all devices. Typically, one device may have a slightly lower resistance, and thus draws more current, heating it more than its sibling devices, causing its resistance to drop further. The electrical load ends up funneling into a single device, which then rapidly fails. Thus, an array of devices may end up no more robust than its weakest component.

The current-hogging effect can be reduced by carefully matching the characteristics of each paralleled device, or by using other design techniques to balance the electrical load. However, maintaining load balance under extreme conditions may not be straightforward. Devices with an intrinsic positive temperature coefficient (PTC) of electrical resistance are less prone to current hogging, but thermal runaway can still occur because of poor heat sinking or other problems.

Many electronic circuits contain special provisions to prevent thermal runaway. This is most often seen in transistor biasing arrangements for high-power output stages. However, when equipment is used above its designed ambient temperature, thermal runaway can still occur in some cases. This occasionally causes equipment failures in hot environments, or when air cooling vents are blocked.

Semiconductors

Silicon shows a peculiar profile, in that its electrical resistance increases with temperature up to about 160 °C, then starts decreasing, and drops further when the melting point is reached. This can lead to thermal runaway phenomena within internal regions of the semiconductor junction; the resistance decreases in the regions which become heated above this threshold, allowing more current to flow through the overheated regions, in turn causing yet more heating in comparison with the surrounding regions, which leads to further temperature increase and resistance decrease. This leads to the phenomenon of current crowding and formation of current filaments (similar to current hogging, but within a single device), and is one of the underlying causes of many semiconductor junction failures.

Bipolar junction transistors (BJTs)

Leakage current increases significantly in bipolar transistors (especially germanium-based bipolar transistors) as they increase in temperature. Depending on the design of the circuit, this increase in leakage current can increase the current flowing through a transistor and thus the power dissipation, causing a further increase in collector-to-emitter leakage current. This is frequently seen in a push–pull stage of a class AB amplifier. If the pull-up and pull-down transistors are biased to have minimal crossover distortion at room temperature, and the biasing is not temperature-compensated, then as the temperature rises both transistors will be increasingly biased on, causing current and power to further increase, and eventually destroying one or both devices.

One rule of thumb to avoid thermal runaway is to keep the operating point of a BJT so that Vce ≤ 1/2Vcc

Another practice is to mount a thermal feedback sensing transistor or other device on the heat sink, to control the crossover bias voltage. As the output transistors heat up, so does the thermal feedback transistor. This in turn causes the thermal feedback transistor to turn on at a slightly lower voltage, reducing the crossover bias voltage, and so reducing the heat dissipated by the output transistors.

If multiple BJT transistors are connected in parallel (which is typical in high current applications), a current hogging problem can occur. Special measures must be taken to control this characteristic vulnerability of BJTs.

In power transistors (which effectively consist of many small transistors in parallel), current hogging can occur between different parts of the transistor itself, with one part of the transistor becoming more hot than the others. This is called second breakdown, and can result in destruction of the transistor even when the average junction temperature seems to be at a safe level.

Power MOSFETs

Power MOSFETs typically increase their on-resistance with temperature. Under some circumstances, power dissipated in this resistance causes more heating of the junction, which further increases the junction temperature, in a positive feedback loop. As a consequence, power MOSFETs have stable and unstable regions of operation. However, the increase of on-resistance with temperature helps balance current across multiple MOSFETs connected in parallel, so current hogging does not occur. If a MOSFET transistor produces more heat than the heatsink can dissipate, then thermal runaway can still destroy the transistors. This problem can be alleviated to a degree by lowering the thermal resistance between the transistor die and the heatsink. See also Thermal Design Power.

Metal oxide varistors (MOVs)

Metal oxide varistors typically develop lower resistance as they heat up. If connected directly across an AC or DC power bus (a common usage for protection against electrical transients), a MOV which has developed a lowered trigger voltage can slide into catastrophic thermal runaway, possibly culminating in a small explosion or fire. To prevent this possibility, fault current is typically limited by a thermal fuse, circuit breaker, or other current limiting device.

Tantalum capacitors

Tantalum capacitors are, under some conditions, prone to self-destruction by thermal runaway. The capacitor typically consists of a sintered tantalum sponge acting as the anode, a manganese dioxide cathode, and a dielectric layer of tantalum pentoxide created on the tantalum sponge surface by anodizing. It may happen that the tantalum oxide layer has weak spots that undergo dielectric breakdown during a voltage spike. The tantalum sponge then comes into direct contact with the manganese dioxide, and increased leakage current causes localized heating; usually, this drives an endothermic chemical reaction that produces manganese(III) oxide and regenerates (self-heals) the tantalum oxide dielectric layer.

However, if the energy dissipated at the failure point is high enough, a self-sustaining exothermic reaction can start, similar to the thermite reaction, with metallic tantalum as fuel and manganese dioxide as oxidizer. This undesirable reaction will destroy the capacitor, producing smoke and possibly flame.

Therefore, tantalum capacitors can be freely deployed in small-signal circuits, but application in high-power circuits must be carefully designed to avoid thermal runaway failures.

Digital logic

The leakage current of logic switching transistors increases with temperature. In rare instances, this may lead to thermal runaway in digital circuits. This is not a common problem, since leakage currents usually make up a small portion of overall power consumption, so the increase in power is fairly modest — for an Athlon 64, the power dissipation increases by about 10% for every 30 degrees Celsius. For a device with a TDP of 100 W, for thermal runaway to occur, the heat sink would have to have a thermal resistivity of over 3 K/W (kelvins per watt), which is about 6 times worse than a stock Athlon 64 heat sink. (A stock Athlon 64 heat sink is rated at 0.34 K/W, although the actual thermal resistance to the environment is somewhat higher, due to the thermal boundary between processor and heatsink, rising temperatures in the case, and other thermal resistances.) Regardless, an inadequate heat sink with a thermal resistance of over 0.5 to 1 K/W would result in the destruction of a 100 W device even without thermal runaway effects.

Batteries

When handled improperly, or if manufactured defectively, some rechargeable batteries can experience thermal runaway resulting in overheating. Sealed cells will sometimes explode violently if safety vents are overwhelmed or nonfunctional. Especially prone to thermal runaway are lithium-ion batteries, most markedly in the form of the lithium polymer battery. Reports of exploding cellphones occasionally appear in newspapers. In 2006, batteries from Apple, HP, Toshiba, Lenovo, Dell and other notebook manufacturers were recalled because of fire and explosions. The Pipeline and Hazardous Materials Safety Administration (PHMSA) of the U.S. Department of Transportation has established regulations regarding the carrying of certain types of batteries on airplanes because of their instability in certain situations. This action was partially inspired by a cargo bay fire on a UPS airplane. One of the possible solutions is in using safer and less reactive anode (lithium titanates) and cathode (lithium iron phosphate) materials — thereby avoiding the cobalt electrodes in many lithium rechargeable cells — together with non-flammable electrolytes based on ionic liquids.

Astrophysics

Runaway thermonuclear reactions can occur in stars when nuclear fusion is ignited in conditions under which the gravitational pressure exerted by overlying layers of the star greatly exceeds thermal pressure, a situation that makes possible rapid increases in temperature through gravitational compression. Such a scenario may arise in stars containing degenerate matter, in which electron degeneracy pressure rather than normal thermal pressure does most of the work of supporting the star against gravity, and in stars undergoing implosion. In all cases, the imbalance arises prior to fusion ignition; otherwise, the fusion reactions would be naturally regulated to counteract temperature changes and stabilize the star. When thermal pressure is in equilibrium with overlying pressure, a star will respond to the increase in temperature and thermal pressure due to initiation of a new exothermic reaction by expanding and cooling. A runaway reaction is only possible when this response is inhibited.

Helium flashes in red giant stars

When stars in the 0.8–2.0 solar mass range exhaust the hydrogen in their cores and become red giants, the helium accumulating in their cores reaches degeneracy before it ignites. When the degenerate core reaches a critical mass of about 0.45 solar masses, helium fusion is ignited and takes off in a runaway fashion, called the helium flash, briefly increasing the star's energy production to a rate 100 billion times normal. About 6% of the core is quickly converted into carbon. While the release is sufficient to convert the core back into normal plasma after a few seconds, it does not disrupt the star, nor immediately change its luminosity. The star then contracts, leaving the red giant phase and continuing its evolution into a stable helium-burning phase.

Novae

A nova results from runaway hydrogen fusion (via the CNO cycle) in the outer layer of a carbon-oxygen white dwarf star. If a white dwarf has a companion star from which it can accrete gas, the material will accumulate in a surface layer made degenerate by the dwarf's intense gravity. Under the right conditions, a sufficiently thick layer of hydrogen is eventually heated to a temperature of 20 million K, igniting runaway fusion. The surface layer is blasted off the white dwarf, increasing luminosity by a factor on the order of 50,000. The white dwarf and companion remain intact, however, so the process can repeat. A much rarer type of nova may occur when the outer layer that ignites is composed of helium.

X-ray bursts

Analogous to the process leading to novae, degenerate matter can also accumulate on the surface of a neutron star that is accreting gas from a close companion. If a sufficiently thick layer of hydrogen accumulates, ignition of runaway hydrogen fusion can then lead to an X-ray burst. As with novae, such bursts tend to repeat and may also be triggered by helium or even carbon fusion. It has been proposed that in the case of "superbursts", runaway breakup of accumulated heavy nuclei into iron group nuclei via photodissociation rather than nuclear fusion could contribute the majority of the energy of the burst.

Type Ia supernovae

A type Ia supernova results from runaway carbon fusion in the core of a carbon-oxygen white dwarf star. If a white dwarf, which is composed almost entirely of degenerate matter, can gain mass from a companion, the increasing temperature and density of material in its core will ignite carbon fusion if the star's mass approaches the Chandrasekhar limit. This leads to an explosion that completely disrupts the star. Luminosity increases by a factor of greater than 5 billion. One way to gain the additional mass would be by accreting gas from a giant star (or even main sequence) companion. A second and apparently more common mechanism to generate the same type of explosion is the merger of two white dwarfs.

Pair-instability supernovae

A pair-instability supernova is believed to result from runaway oxygen fusion in the core of a massive, 130–250 solar mass, low to moderate metallicity star. According to theory, in such a star, a large but relatively low density core of nonfusing oxygen builds up, with its weight supported by the pressure of gamma rays produced by the extreme temperature. As the core heats further, the gamma rays eventually begin to pass the energy threshold needed for collision-induced decay into electron-positron pairs, a process called pair production. This causes a drop in the pressure within the core, leading it to contract and heat further, causing more pair production, a further pressure drop, and so on. The core starts to undergo gravitational collapse. At some point this ignites runaway oxygen fusion, releasing enough energy to obliterate the star. These explosions are rare, perhaps about one per 100,000 supernovae.

Comparison to nonrunaway supernovae

Not all supernovae are triggered by runaway nuclear fusion. Type Ib, Ic and type II supernovae also undergo core collapse, but because they have exhausted their supply of atomic nuclei capable of undergoing exothermic fusion reactions, they collapse all the way into neutron stars, or in the higher-mass cases, stellar black holes, powering explosions by the release of gravitational potential energy (largely via release of neutrinos). It is the absence of runaway fusion reactions that allows such supernovae to leave behind compact stellar remnants.

Introduction to entropy

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