Amorphous silicon

From Wikipedia, the free encyclopedia

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

 

Amorphous silicon:

• Thin-film silicon solar panels on rooftop
• Schematic structures of crystalline silicon, amorphous silicon, and amorphous hydrogenated silicon
• Solar calculator with amorphous solar cell (upper right corner) and LCDs.

Amorphous silicon (a-Si) is the non-crystalline form of silicon used for solar cells and thin-film transistors in LCDs.

Used as semiconductor material for a-Si solar cells, or thin-film silicon solar cells, it is deposited in thin films onto a variety of flexible substrates, such as glass, metal and plastic. Amorphous silicon cells generally feature low efficiency.

As a second-generation thin-film solar cell technology, amorphous silicon was once expected to become a major contributor in the fast-growing worldwide photovoltaic market, but has since lost its significance due to strong competition from conventional crystalline silicon cells and other thin-film technologies such as CdTe and CIGS. Amorphous silicon is a preferred material for the thin film transistor (TFT) elements of liquid crystal displays (LCDs) and for x-ray imagers.

Amorphous silicon differs from other allotropic variations, such as monocrystalline silicon—a single crystal, and polycrystalline silicon, that consists of small grains, also known as crystallites.

Description

Silicon is a fourfold coordinated atom that is normally tetrahedrally bonded to four neighboring silicon atoms. In crystalline silicon (c-Si) this tetrahedral structure continues over a large range, thus forming a well-ordered crystal lattice.

In amorphous silicon this long range order is not present. Rather, the atoms form a continuous random network. Moreover, not all the atoms within amorphous silicon are fourfold coordinated. Due to the disordered nature of the material some atoms have a dangling bond. Physically, these dangling bonds represent defects in the continuous random network and may cause anomalous electrical behavior.

The material can be passivated by hydrogen, which bonds to the dangling bonds and can reduce the dangling bond density by several orders of magnitude. Hydrogenated amorphous silicon (a-Si:H) has a sufficiently low amount of defects to be used within devices such as solar photovoltaic cells, particularly in the protocrystalline growth regime. However, hydrogenation is associated with light-induced degradation of the material, termed the Staebler–Wronski effect.

Schematic of allotropic forms of silicon: monocrystalline, polycrystalline, and amorphous silicon

Amorphous silicon and carbon

Amorphous alloys of silicon and carbon (amorphous silicon carbide, also hydrogenated, a-Si_1−xC_x:H) are an interesting variant. Introduction of carbon atoms adds extra degrees of freedom for control of the properties of the material. The film could also be made transparent to visible light.

Increasing the concentration of carbon in the alloy widens the electronic gap between conduction and valence bands (also called "optical gap" and bandgap). This increases the light efficiency of solar cells made with amorphous silicon carbide layers. On the other hand, the electronic properties as a semiconductor (mainly electron mobility), are adversely affected by the increasing content of carbon in the alloy, presumably due to the increased disorder in the atomic network.

Several studies are found in the scientific literature, mainly investigating the effects of deposition parameters on electronic quality, but practical applications of amorphous silicon carbide in commercial devices are still lacking.

Properties

The density of ion implanted amorphous Si has been calculated as 4.90×10²² atom/cm³ (2.285 g/cm³) at 300 K. This was done using thin (5 micron) strips of amorphous silicon. This density is 1.8±0.1% less dense than crystalline Si at 300 K. Silicon is one of the few elements that expands upon cooling and has a lower density as a solid than as a liquid.

Hydrogenated amorphous silicon

Unhydrogenated a-Si has a very high defect density which leads to undesirable semiconductor properties such as poor photoconductivity and prevents doping which is critical to engineering semiconductor properties. By introducing hydrogen during the fabrication of amorphous silicon, photoconductivity is significantly improved and doping is made possible. Hydrogenated amorphous silicon, a-Si:H, was first fabricated in 1969 by Chittick, Alexander and Sterling by deposition using a silane gas (SiH₄) precursor. The resulting material showed a lower defect density and increased conductivity due to impurities. Interest in a-Si:H came when (in 1975), LeComber and Spear discovered the ability for substitutional doping of a-Si:H using phosphine (n-type) or diborane (p-type). The role of hydrogen in reducing defects was verified by Paul's group at Harvard who found a hydrogen concentration of about 10 atomic % through IR vibration, which for Si-H bonds has a frequency of about 2000 cm⁻¹. Starting in the 1970s, a-Si:H was developed in solar cells by David E. Carlson and C. R. Wronski at RCA Laboratories. Conversion efficiency steadily climbed to about 13.6% in 2015.

Deposition processes

	CVD	PECVD	Catalytic CVD	Sputtering
Type of film	a-Si:H	a-Si:H	a-Si:H	a-Si
Unique application		Large-area electronics		Hydrogen-free deposition
Chamber temperature	600C	30–300C		30–1000C
Active element temperature			2000C
Chamber pressure	0.1–10 Torr	0.1–10 Torr		0.001–0.1 Torr
Physical principle	Thermolysis	Plasma-induced dissociation	Thermolysis	Ionization of Si source
Facilitators			W/Ta heated wires	Argon cations
Typical drive voltage		RF 13.56 MHz; 0.01-1W/cm2
Si source	SiH4 gas	SiH4 gas	SiH4 gas	Target
Substrate temperature	controllable	controllable	controllable	controllable

Applications

While a-Si suffers from lower electronic performance compared to c-Si, it is much more flexible in its applications. For example, a-Si layers can be made thinner than c-Si, which may produce savings on silicon material cost.

One further advantage is that a-Si can be deposited at very low temperatures, e.g., as low as 75 degrees Celsius. This allows deposition on not only glass, but on plastic or even on paper substrates as well, making it a candidate for a roll-to-roll processing technique. Once deposited, a-Si can be doped in a fashion similar to c-Si, to form p-type or n-type layers and ultimately to form electronic devices.

Another advantage is that a-Si can be deposited over large areas by PECVD. The design of the PECVD system has great impact on the production cost of such panel, therefore most equipment suppliers put their focus on the design of PECVD for higher throughput, that leads to lower manufacturing cost particularly when the silane is recycled.

Arrays of small (under 1 mm by 1 mm) a-Si photodiodes on glass are used as visible-light image sensors in some flat panel detectors for fluoroscopy and radiography.

Photovoltaics

See also: Thin-film solar cell

The "Teal Photon" solar-powered calculator produced in the late 1970s

Hydrogenated amorphous silicon (a-Si:H) has been used as a photovoltaic solar cell material for devices which require very little power, such as pocket calculators, because their lower performance compared to conventional crystalline silicon (c-Si) solar cells is more than offset by their simplified and lower cost of deposition onto a substrate. Moreover, the vastly higher shunt resistance of the p-i-n device means that acceptable performance is achieved even at very low light levels. The first solar-powered calculators were already available in the late 1970s, such as the Royal Solar 1, Sharp EL-8026, and Teal Photon.

More recently, improvements in a-Si:H construction techniques have made them more attractive for large-area solar cell use as well. Here their lower inherent efficiency is made up, at least partially, by their thinness – higher efficiencies can be reached by stacking several thin-film cells on top of each other, each one tuned to work well at a specific frequency of light. This approach is not applicable to c-Si cells, which are thick as a result of its indirect band-gap and are therefore largely opaque, blocking light from reaching other layers in a stack.

The source of the low efficiency of amorphous silicon photovoltaics is due largely to the low hole mobility of the material. This low hole mobility has been attributed to many physical aspects of the material, including the presence of dangling bonds (silicon with 3 bonds), floating bonds (silicon with 5 bonds), as well as bond reconfigurations. While much work has been done to control these sources of low mobility, evidence suggests that the multitude of interacting defects may lead to the mobility being inherently limited, as reducing one type of defect leads to formation others.

The main advantage of a-Si:H in large scale production is not efficiency, but cost. a-Si:H cells use only a fraction of the silicon needed for typical c-Si cells, and the cost of the silicon has historically been a significant contributor to cell cost. However, the higher costs of manufacture due to the multi-layer construction have, to date, made a-Si:H unattractive except in roles where their thinness or flexibility are an advantage.

Typically, amorphous silicon thin-film cells use a p-i-n structure. The placement of the p-type layer on top is also due to the lower hole mobility, allowing the holes to traverse a shorter average distance for collection to the top contact. Typical panel structure includes front side glass, TCO, thin-film silicon, back contact, polyvinyl butyral (PVB) and back side glass. Uni-Solar, a division of Energy Conversion Devices produced a version of flexible backings, used in roll-on roofing products. However, the world's largest manufacturer of amorphous silicon photovoltaics had to file for bankruptcy in 2012, as it could not compete with the rapidly declining prices of conventional solar panels.

Microcrystalline and micromorphous silicon

Main articles: Nanocrystalline silicon and Micromorph

Microcrystalline silicon (also called nanocrystalline silicon) is amorphous silicon, but also contains small crystals. It absorbs a broader spectrum of light and is flexible. Micromorphous silicon module technology combines two different types of silicon, amorphous and microcrystalline silicon, in a top and a bottom photovoltaic cell. Sharp produces cells using this system in order to more efficiently capture blue light, increasing the efficiency of the cells during the time where there is no direct sunlight falling on them. Protocrystalline silicon is often used to optimize the open circuit voltage of a-Si photovoltaics.

Large-scale production

United Solar Ovonic roll-to-roll solar photovoltaic production line with 30 MW annual capacity

Xunlight Corporation, which has received over $40 million of institutional investments, has completed the installation of its first 25 MW wide-web, roll-to-roll photovoltaic manufacturing equipment for the production of thin-film silicon PV modules. Anwell Technologies has also completed the installation of its first 40 MW a-Si thin film solar panel manufacturing facility in Henan with its in-house designed multi-substrate-multi-chamber PECVD equipment.

Photovoltaic thermal hybrid solar collectors

Aerospace product with flexible thin-film solar PV from United Solar Ovonic

Photovoltaic thermal hybrid solar collectors (PVT), are systems that convert solar radiation into electrical energy and thermal energy. These systems combine a solar cell, which converts electromagnetic radiation (photons) into electricity, with a solar thermal collector, which captures the remaining energy and removes waste heat from the solar PV module. Solar cells suffer from a drop in efficiency with the rise in temperature due to increased resistance. Most such systems can be engineered to carry heat away from the solar cells thereby cooling the cells and thus improving their efficiency by lowering resistance. Although this is an effective method, it causes the thermal component to under-perform compared to a solar thermal collector. Recent research showed that a-Si:H PV with low temperature coefficients allow the PVT to be operated at high temperatures, creating a more symbiotic PVT system and improving performance of the a-Si:H PV by about 10%.

Thin-film-transistor liquid-crystal display

Main article: Thin-film-transistor liquid-crystal display

Amorphous silicon has become the material of choice for the active layer in thin-film transistors (TFTs), which are most widely used in large-area electronics applications, mainly for liquid-crystal displays (LCDs).

Thin-film-transistor liquid-crystal display (TFT-LCD) show a similar circuit layout process to that of semiconductor products. However, rather than fabricating the transistors from silicon, that is formed into a crystalline silicon wafer, they are made from a thin film of amorphous silicon that is deposited on a glass panel. The silicon layer for TFT-LCDs is typically deposited using the PECVD process. Transistors take up only a small fraction of the area of each pixel and the rest of the silicon film is etched away to allow light to easily pass through it.

Polycrystalline silicon is sometimes used in displays requiring higher TFT performance. Examples include small high-resolution displays such as those found in projectors or viewfinders. Amorphous silicon-based TFTs are by far the most common, due to their lower production cost, whereas polycrystalline silicon TFTs are more costly and much more difficult to produce.

Shock therapy (economics)

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Shock_therapy_(economics)

In economics, shock therapy is a group of policies intended to be implemented simultaneously in order to liberalize the economy, including liberalization of all prices, privatization, trade liberalization, and stabilization via tight monetary policies and fiscal policies. In the case of post-Communist states, it was implemented in order to transition from a command economy to a market economy.

Overview

Shock therapy is a program intended to economically liberalize a mixed economy or transition a planned economy or developmentalist economy to a free-market economy through sudden and dramatic neoliberal reform. Shock therapy policies generally include ending price controls, stopping government subsidies, privatizing state-owned industries, and tighter fiscal policies, such as higher tax rates and lowered government spending. In essence, shock therapy policies can be distilled to price liberalization accompanied by strict austerity.

The first instance of shock therapy was the neoliberal reforms of Chile under Pinochet, carried out after the military coup by Augusto Pinochet. The reforms were based on the liberal economic ideas centered on the University of Chicago, which became known as the Chicago Boys. The term is also applied to Bolivia's case. Bolivia successfully tackled hyperinflation in 1985 under President Victor Paz Estenssoro and Minister of Planning Gonzalo Sánchez de Lozada, using the ideas of economist Jeffrey Sachs.

Economic liberalism rose to prominence after the 1960s and liberal shock therapy became increasingly used as a response to economic crises, for example by the International Monetary Fund (IMF) in the 1997 Asian Financial Crisis. Shock therapy has been controversial, with its proponents arguing that it helped to end economic crises, stabilized economies, and paved the way for economic growth, while its critics including economist Joseph Stiglitz believed that it helped deepen them unnecessarily and created unnecessary social suffering.

In post-Soviet Russia and other post-Communist states, neoliberal reforms based on the Washington Consensus resulted in a surge in excess mortality and decreasing life expectancy, along with rising economic inequality, corruption, and poverty. Isabella Weber of the University of Massachusetts said: "As a result of shock therapy, Russia experienced a rise in mortality beyond that of any previous peacetime experiences of an industrialized country." The Gini ratio increased by an average of 9 points for all post-Communist states. The average post-Communist state had returned to 1989 levels of per-capita GDP by 2005, although some are still far behind that. In Russia, the average real income for 99 percent of people was lower in 2015 than in 1991. According to William Easterly, successful market economies rest on a framework of law, regulation, and established practice, which cannot be instantaneously created in a society that was formerly authoritarian, heavily centralised, and subject to state ownership of assets. German historian Philipp Ther asserted that the imposition of shock therapy had little to do with future economic growth.

History

West Germany, 1948

Background

Germany ended the European Theatre of World War II with its unconditional surrender on the 8 May 1945. April 1945 to July 1947 saw the Allied occupation of Germany implement Joint Chiefs of Staff directive 1067 (JCS 1067). This directive aimed to transfer Germany's economy from one centered on heavy industry to a pastoral one to prevent Germany from having the capacity for war. Civilian industries that might have military potential, which in the modern era of "total war" included virtually all, were severely restricted. The restriction of the latter was set to Germany's approved peacetime needs, which were set on the average European standard. To achieve this, each type of industry was subsequently reviewed to see how many factories Germany required under these minimum level of industry requirements.

It soon became obvious that this policy was not sustainable. Germany could not grow enough food for itself, and malnutrition was becoming increasingly common. The European post-war economic recovery did not materialise and it became increasingly obvious that the European economy had depended on German industry. In July 1947, President Harry S. Truman rescinded on "national security grounds" the punitive JCS 1067, which had directed the U.S. forces of occupation in Germany to "take no steps looking toward the economic rehabilitation of Germany." It was replaced by JCS 1779, which instead stressed that "[a]n orderly, prosperous Europe requires the economic contributions of a stable and productive Germany."

By 1948, Germany suffered from rampant hyperinflation. The currency of the time (the Reichsmark) had no public confidence, and thanks to that and price controls, black market trading boomed and bartering proliferated. Banks were over their heads in debt and surplus currency abounded. Thanks to the introduction of JCS 1779 and the first Allied attempts to set up German governance, something could be done about this. Ludwig Erhard, an economist, who had spent much time working on the problem of post war recovery, had worked his way up the administration created by the occupying American forces until he became the Director of Economics in the Bizonal Economic Council in the joint British and American occupied zones (which later, with the addition of the French occupied territory, became the basis for West Germany).

Economic reforms

Currency reform took effect on June 20, 1948, through the introduction of the Deutsche Mark to replace the Reichsmark and by transferring to the Bank deutscher Länder the sole right to print money.

Under the German Currency Conversion Law on 27 June, private non-bank credit balances were converted at a rate of 10 RM to 1 DM, with half remaining in a frozen bank account. Although the money stock was very small in terms of national product, the adjustment in the price structure immediately led to sharp price increases, fueled by the high velocity of money through the system. As a result, on 4 October, the military governments wiped out 70% of the remaining frozen balances, resulting in an effective exchange of 10:0.65. Holders of financial assets (including many small-time savers) were dispossessed and the banks' debt in Reichsmarks was eliminated, transferred instead into claims on the Lander and later the Federal Government. Wages, rents, pensions and other recurring liabilities were transferred at 1:1. On the day of the currency reform, Ludwig Erhard announced, despite the reservations of the Allies, that rationing would be considerably relaxed and price controls abolished.

Results

In the short term, the currency reforms and abolition of price controls helped end hyperinflation. The new currency enjoyed considerable confidence and was accepted by the public as a medium of payment. The currency reforms had ensured that money was once scarcer, and the relaxation of price controls created incentives for production, sales and earning this money. The removal of price controls also meant shops filled up with goods again, which was a huge psychological factor in the adoption of the new currency.

As would later also occur in the post-Soviet states, shock therapy resulted in redistribution from the bottom-up, benefiting those who held non-monetary assets. Although Erhard's price liberalization excluded rents and essential goods, it still caused an increase in inflation and resulted in a general strike. A turn from a free market to a social market economy followed under the Jedermann Programm, and by late 1948 "the German transition followed a dual-track pattern with a planned core and a market-coordinated periphery."

Chile, 1975

Main article: Miracle of Chile

Economic reforms

The government welcomed foreign investment and eliminated protectionist trade barriers, forcing Chilean businesses to compete with imports on an equal footing, or else go out of business. The main copper company, Codelco, remained in government hands due to the nationalization of copper completed by Salvador Allende but private companies were allowed to explore and develop new mines.

In the short term, the reforms stabilized the economy. In the long term, Chile has had higher GDP growth than its neighboring countries but with a noticeable increase of income inequality.

Bolivia, 1985

Background

Between 1979 and 1982, Bolivia was ruled by a series of coups, countercoups, and caretaker governments, including the notorious dictatorship of Luis García Meza Tejada. This period of political instability set the stage for the hyperinflation that later crippled the country. In October 1982, the military convened a Congress elected in 1980 to lead choose a new Chief Executive. The country elected Hernán Siles Zuazo, under whose term the galloping hyperinflationary process started. Zuazo received scant support from the political parties or members of congress, most of whom were eager to flex their newly acquired political muscles after so many years of authoritarianism. Zuazo refused to take extra-constitutional powers (as previous military governments had done in similar crises) and concentrated on preserving the democracy instead, shortening his term by one year in response to his unpopularity and the crisis racking his country. On 6 August 1985, President Víctor Paz Estenssoro was elected.

Prelude to Decree 21060

On 29 August, just three weeks after the election of Víctor Paz Estenssoro as President, and the appointment of Gonzalo Sánchez de Lozada, the architect of shock therapy, as Planning Minister, Decree 21060 was passed. Decree 21060 covered all aspects of the Bolivian economy, later referred to as shock therapy. In the run-up to the decree, Gonzalo Sánchez de Lozada recalled what the new government set out to do, saying: "People felt you couldn't stop hyperinflation in a democracy; that you had to have a military government, an authoritarian government to take all these tough steps that had to be taken. Bolivia was the first country to stop hyperinflation in a democracy without depriving people of their civil rights and without violating human rights."

About the three weeks between the inauguration of the President and decree 21060, he said: "We spent one week saying, 'Do we really need to do something? Do we really need radical change?' and then another week debating shock treatment versus gradualism. Finally, we took one week to write it all up." Once they had decided to act, de Lozada recalled of "a big discussion whether you could stop hyperinflation or inflation, period, by taking gradual steps". He added: "Many people said you had to take it slowly. You have to cure the patient. Shock treatment means you have a very sick patient [and] you have to operate before the patient dies. You have to get the cancer out, or you have to stop the infection." He explained: "That's why we coined the phrase that inflation is like a tiger and you have only one shot; if you don't get it with that one shot, it'll get you. You have a credibility that you have to achieve. If you keep to gradualism, people don't believe you, and the hyperinflation just keeps roaring stronger. So shock therapy is get it over, get it done, stop hyperinflation, and then start rebuilding your economy so you achieve growth."

Decree 21060

Main article: Decree 21060

Decree 21060 included the following measures:

• Allowing the peso to float.
• Ending price controls and eliminating subsidies to the public sector.
• Laying off two-thirds of the employees of the state oil and tin companies and freezing the pay of the remaining employees and public sector workers.
• Liberalising import tariffs by imposing a uniform 20% tariff.
• Stopping the payment of foreign debt under a deal negotiated with the IMF.

Post-Soviet states

With the exception of Belarus, the Eastern European states adopted shock therapy. Nearly all of these post-Soviet states suffered deep and prolonged recessions after shock therapy, with poverty increasing more than tenfold. The resulting crisis of the 1990s was twice as intense as the Great Depression in the countries of Western Europe and the United States in the 1930s. The hypothesized one time jump in prices intended as part of shock therapy actually led to a lengthy period of extremely high inflation with a drop in output and subsequent low growth rates. Shock therapy devalued the modest wealth accumulated by individuals under socialism and amounted to a regressive redistribution of wealth in favor of elites who held non-monetary assets. Contrary to the expectation of shock therapy proponents, Russia's rapid transition to the market increased corruption, rather than alleviating it.

The cost to human life was profound, as Russia suffered the worst peace time increase in mortality experienced by any industrialized country. For the years 1987 and 1988, roughly 2% of Russia population lived in poverty (surviving on less than $4 a day), by 1993-1995, it was 50%. According to Kristen Ghodsee and Mitchell A. Orenstein, a significant body of scholarship demonstrates that the rapid privatization schemes associated with neoliberal economic reforms did result in poorer health outcomes in former Eastern Bloc countries during the transition to capitalism, with the World Health Organization itself stating "IMF economic reform programs are associated with significantly worsened tuberculosis incidence, prevalence, and mortality rates in post-communist Eastern European and former Soviet countries." They add that Western institutions and economists were indifferent to the consequences of the shock therapy they were advocating as their priorities included permanently dismantling the state socialist system and integrating these countries into the emerging global capitalist economy, and that many citizens of the former Eastern Bloc countries came to believe that Western powers were deliberately inflicting this suffering upon them as punishment for defying Western ideals about liberal democracy and market economics.

Arguments exist whether these adverse outcomes were due to the general collapse of the Soviet economy (which began before 1989) or the policies subsequently implemented or a combination of both. Sachs himself resigned from his post as advisor, after stating that he felt his advice was unheeded and his policy recommendations were not actually put into practice. In addition to his criticism of the way in which Russian authorities handled the reforms, Sachs has also criticized the U.S. and the IMF for not providing large-scale financial aid to Russia, which he felt was integral to the success of the reforms.

Advocates of shock therapy view Poland as the success story of shock therapy in the post-communist states and claim that shock therapy was not applied appropriately in Russia, while critics claim that Poland's reforms were the most gradualist of all the countries and contrast China's reforms with those of Russia and their vastly different effects. Some research suggests that the very fast pace of 'shock therapy' privatization mattered and had a particularly harsh effect on the death rate in Russia.

Background in Poland

After the failure of the Communist government in the elections of June 4, 1989, it became clear that the previous regime was no longer legitimate. The unofficial talks at Magdalenka and then the Polish Round Table talks of 1989 allowed for a peaceful transition of power to the democratically elected government.

The economic situation was that inflation was high, peaking at around 600%, and the majority of state-owned monopolies and holdings were largely ineffective and completely obsolete in terms of technology. Although there was practically no unemployment in Poland, wages were low and the shortage economy led to a lack of even the most basic foodstuffs in the shops. Unlike the other post-communist countries, however, Poland did have some experience with a capitalist economy, as there was still private property in agriculture and food was still sold in farmers' markets.

In September 1989 a commission of experts was formed under the presidency of Leszek Balcerowicz, Poland's leading economist, Minister of Finance and deputy Premier of Poland. Among the members of the commission were Jeffrey Sachs, Stanisław Gomułka, Stefan Kawalec and Wojciech Misiąg.

Balcerowicz Plan

Main article: Balcerowicz Plan

On October 6 the program was presented on public television and in December the Sejm passed a packet of 11 acts, all of which were signed by the president on December 31, 1989. These were:

1. Act on Financial Economy Within State-owned Companies, which allowed for state-owned businesses to declare bankruptcy and ended the fiction by which companies were able to exist even if their effectiveness and accountability was close to none.
2. Act on Banking Law, which forbade financing the state budget deficit by the national central bank and forbade the issue of new currency.
3. Act on Credits, which abolished the preferential laws on credits for state-owned companies and tied interest rates to inflation.
4. Act on Taxation of Excessive Wage Rise, introducing the so-called popiwek tax limiting the wage increase in state-owned companies in order to limit hyperinflation.
5. Act on New Rules of Taxation, introducing common taxation for all companies and abolishing special taxes that could previously have been applied to private companies through means of administrative decision.
6. Act on Economic Activity of Foreign Investors, allowing foreign companies and private people to invest in Poland and export their profits abroad.
7. Act on Foreign Currencies, introducing internal exchangeability of the zloty and abolishing the state monopoly in international trade.
8. Act on Customs Law, creating a uniform customs rate for all companies.
9. Act on Employment, regulating the duties of unemployment agencies.
10. Act on Special Circumstances Under Which a Worker Could be Laid Off, protecting the workers of state firms from being fired in large numbers and guaranteeing unemployment grants and severance pay.

Privatization of companies was left until later.

Results in Poland

In the short term, the reforms smothered the building hyperinflation before it reached high levels, ended food shortages, restored goods on the shelves of shops and halved the absence of employees in the work place. However, the reforms also caused many state companies to close at once, leaving their workers unemployed, and government statistics show this change as unemployment rose from 0.3% in January 1990 (just after the reforms) to 6.5% by the end of that year, and a shrinking in the GDP for the next two consecutive years by 9.78% in the first and 7.02% (see main article).

In the long term, the reforms paved the way for economic recovery, with the GDP growing steadily to about 6–7% between 1995–7, falling to a low of 1.2% in 2001 before rising back up to the 6–7% region by 2007, often led by small service businesses, long suppressed by the Communist government. However, despite GDP indicating prosperity for Poland, the unemployment rate continued to rise steadily, peaking at 16.9% in July 1994 before steadily falling down to a low of 9.5% in August 1998 before rising once more to a high of 20.7% in February 2003, from which it had fallen until the year 2008. During the early years, the unemployment rate is thought to have been lower due to many of those claiming unemployment working in the grey (informal) economy, although this can account for no more than 5% of the unemployment rate.

Ownership of consumables (cars, TVs, VCRs, washing machines, refrigerators, personal computers, etc.) boomed, as did consumption of fruit and vegetables, meat and fish. However, the huge economic adjustment Poland underwent created massive anxiety.

As of 2008, the GNP was 77% higher than in 1989. Moreover, inequality in Poland actually decreased right after the economic reforms were implemented, although it rose back up again in later years. Today, although Poland is confronted with a variety of economic problems, it still has a higher GDP than during communist times, and a gradually developing economy. Poland was converging towards the EU in regards to income level in 1993–2004. According to Financial Times, Poland's shock therapy paved the way for entrepreneurs and helped to build an economy that was less vulnerable to external shock than Poland’s neighbours. In 2009, while the rest of Europe was in recession, Poland continued to grow, without a single quarter of negative growth.

Theory

Origins of the term "shock therapy"

The term was popularized by Naomi Klein. In her 2007 book The Shock Doctrine, she argues that neoliberal free market policies (as advocated by the economist Milton Friedman) have risen to prominence globally because of a strategy of "shock therapy". She argues these policies are often unpopular, result in greater inequality and are accompanied by political and social "shocks" such as military coups, state sponsored terror, sudden unemployment and the suppression of labor.

The economist Jeffrey Sachs (sometimes credited with coining the term) says he never picked the term "shock therapy", does not much like it, and asserts that the term "was something that was overlaid by journalism and public discussion" and that the term "sounds a lot more painful in a way than what it is". Sachs' ideas on what has been referred by non-economists as "shock therapy" were based on studying historic periods of monetary and economic crisis and noting that a decisive stroke could end monetary chaos, often in a day.

Pace of privatization

Shock therapy proponents Sachs and Lipton argued in 1990, "The great conundrum is how to privatize a vast array of firms in a manner that is equitable, swift, politically viable, and likely to create an effective structure of corporate control." They recommended that the pace "must be rapid, but not reckless," and should "probably be carried out by many means." In the view of shock therapy proponents, trade liberalization requires domestic price liberalization first; thus a "big bang" in price liberalization underlying both privatization and trade liberalization forms the "shock" in the moniker "shock therapy."

In practice, the rapid application of shock therapy proved generally disastrous in the post-Soviet states.

Departure from "the invisible hand"

Although economists have sometimes referred to shock therapy "creating" markets, shock therapy does not in fact create such new structures or institutions. The hope among shock therapy proponents is instead that the destruction of a command or planned economy would automatically result in a market economy. The expectation was that after the command economy or planned economy was "shocked to death," the "invisible hand" might emerge.

The expectations that a market economy would emerge following the imposition of shock therapy differ from Adam Smith's original metaphor of the "invisible hand". Smith viewed the market as emerging slowly as the institutions that facilitate market exchange develop, and with the "invisible hand" the price mechanism could emerge.

Illusionary shock

Illusion therapy refers to the imposition of shock economic policies on economy in a way that the society doesn't feel the shock or assumes that the dramatic change in policies is not as shocking or radical as it is in the real world. The first experience of illusion therapy has been documented after the implementation of Iran's subsidy reform project.

Binomial nomenclature

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Binomial_nomenclature

Orcinus orca, the orca or the killer whale

Echinopsis pachanoi, the San Pedro cactus

In taxonomy, binomial nomenclature ("two-term naming system"), also called binominal nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name (which may be shortened to just "binomial"), a binomen, binominal name, or a scientific name; more informally it is also historically called a Latin name.

The first part of the name – the generic name – identifies the genus to which the species belongs, whereas the second part – the specific name or specific epithet – distinguishes the species within the genus. For example, modern humans belong to the genus Homo and within this genus to the species Homo sapiens. Tyrannosaurus rex is likely the most widely known binomial. The formal introduction of this system of naming species is credited to Carl Linnaeus, effectively beginning with his work Species Plantarum in 1753. But as early as 1622, Gaspard Bauhin introduced in his book Pinax theatri botanici (English, Illustrated exposition of plants) containing many names of genera that were later adopted by Linnaeus.

The application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature (ICZN) for animals and the International Code of Nomenclature for algae, fungi, and plants (ICNafp or ICN). Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences in the terminology they use and their particular rules.

In modern usage, the first letter of the generic name is always capitalized in writing, while that of the specific epithet is not, even when derived from a proper noun such as the name of a person or place. Similarly, both parts are italicized in normal text (or underlined in handwriting). Thus the binomial name of the annual phlox (named after botanist Thomas Drummond) is now written as Phlox drummondii. Often, after a species name is introduced in a text, the generic name is abbreviated to the first letter in subsequent mentions (e.g., P. drummondii).

In scientific works, the authority for a binomial name is usually given, at least when it is first mentioned, and the year of publication may be specified.

• In zoology
  • "Patella vulgata Linnaeus, 1758". The name "Linnaeus" tells the reader who published the name and description for this species; 1758 is the year the name and original description were published (in this case, in the 10th edition of the book Systema Naturae).
  • "Passer domesticus (Linnaeus, 1758)". The original name given by Linnaeus was Fringilla domestica; the parentheses indicate that the species is now placed in a different genus. The ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs usually include such information.
• In botany
  • "Amaranthus retroflexus L." – "L." is the standard abbreviation used for "Linnaeus".
  • "Hyacinthoides italica (L.) Rothm." – Linnaeus first named this bluebell species Scilla italica; Rothmaler transferred it to the genus Hyacinthoides; the ICNafp does not require that the dates of either publication be specified.

Etymology

The name is composed of two word-forming elements: bi- (Latin prefix meaning 'two') and nomial (the adjective form of nomen, Latin for 'name'). In Medieval Latin, the related word binomium was used to signify one term in a binomial expression in mathematics.^[6] In fact, the Latin word binomium may validly refer to either of the epithets in the binomial name, which can equally be referred to as a binomen (pl. binomina).

History

See also: Biological classification: Early systems

Carl Linnaeus (1707–1778), a Swedish botanist, invented the modern system of binomial nomenclature.

Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name that was from one to several words long. Together they formed a system of polynomial nomenclature. These names had two separate functions. First, to designate or label the species, and second, to be a diagnosis or description; however, these two goals were eventually found to be incompatible. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; but as more species were discovered, the names necessarily became longer and unwieldy, for instance, Plantago foliis ovato-lanceolatus pubescentibus, spica cylindrica, scapo tereti ("plantain with pubescent ovate-lanceolate leaves, a cylindric spike and a terete scape"), which we know today as Plantago media.

Such "polynomial names" may sometimes look like binomials, but are significantly different. For example, Gerard's herbal (as amended by Johnson) describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort; the second, Phalangium non ramosum, Unbranched Spiderwort. The other ... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels.

The Bauhins, in particular Caspar Bauhin (1560–1624), took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of strictly binomial nomenclature is due to Swedish botanist and physician Carl Linnaeus (1707–1778). It was in Linnaeus's 1753 Species Plantarum that he began consistently using a one-word trivial name (nomen triviale) after a generic name (genus name) in a system of binomial nomenclature. Trivial names had already appeared in his Critica Botanica (1737) and Philosophia Botanica (1751). This trivial name is what is now known as a specific epithet (ICNafp) or specific name (ICZN). The Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word.

Linnaeus's trivial names introduced an important new idea, namely that the function of a name could simply be to give a species a unique label. This meant that the name no longer needs to be descriptive; for example, both parts could be derived from the names of people. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virginiana, where the genus name honoured John Tradescant the Younger, an English botanist and gardener. A bird in the parrot family was named Psittacus alexandri, meaning "Alexander's parrot", after Alexander the Great, whose armies introduced eastern parakeets to Greece. Linnaeus's trivial names were much easier to remember and use than the parallel polynomial names and eventually replaced them.

Value

The bacterium Escherichia coli, commonly shortened to E. coli

The value of the binomial nomenclature system derives primarily from its economy, its widespread use, and the uniqueness and stability of names that the Codes of Zoological and Botanical, Bacterial and Viral Nomenclature provide:

• Economy. Compared to the polynomial system which it replaced, a binomial name is shorter and easier to remember. It corresponds to the widespread system of family name plus given name(s) used to name people in many cultures.
• Widespread use. The binomial system of nomenclature is governed by international codes and is used by biologists worldwide. A few binomials have also entered common speech, such as Homo sapiens, E. coli, Boa constrictor, Tyrannosaurus rex, and Aloe vera.
• Uniqueness. Provided that taxonomists agree as to the limits of a species, it can have only one name that is correct under the appropriate nomenclature code, generally the earliest published if two or more names are accidentally assigned to a species. However, establishing that two names actually refer to the same species and then determining which has priority can be difficult, particularly if the species was named by biologists from different countries. Therefore, a species may have more than one regularly used name; all but one of these names are "synonyms". Furthermore, within zoology or botany, each species name applies to only one species. If a name is used more than once, it is called a homonym.

  

  Erithacus rubecula superbus, the Tenerife robin or petirrojo

• Stability. Although stability is far from absolute, the procedures associated with establishing binomial names, such as the principle of priority, tend to favor stability. For example, when species are transferred between genera (as not uncommonly happens as a result of new knowledge), the second part of the binomial is kept the same (unless it becomes a homonym). Thus, there is disagreement among botanists as to whether the genera Chionodoxa and Scilla are sufficiently different for them to be kept separate. Those who keep them separate give the plant commonly grown in gardens in Europe the name Chionodoxa siehei; those who do not give it the name Scilla siehei. The siehei element is constant. Similarly, if what were previously thought to be two distinct species are demoted to a lower rank, such as subspecies, the second part of the binomial name is retained as a trinomen (the third part of the new name). Thus, the Tenerife robin may be treated as a different species from the European robin, in which case its name is Erithacus superbus, or as only a subspecies, in which case its name is Erithacus rubecula superbus. The superbus element of the name is constant, as is its authorship and year of publication.

Problems

Binomial nomenclature for species has the effect that when a species is moved from one genus to another, sometimes the specific name or epithet must be changed as well. This may happen because the specific name is already used in the new genus, or to agree in gender with the new genus if the specific epithet is an adjective modifying the genus name. Some biologists have argued for the combination of the genus name and specific epithet into a single unambiguous name, or for the use of uninomials (as used in nomenclature of ranks above species).

Because genus names are unique only within a nomenclature code, it is possible for two or more species to share the same genus name and even the same binomial if they occur in different kingdoms. At least 1,258 instances of genus name duplication occur (mainly between zoology and botany).

Relationship to classification and taxonomy

Nomenclature (including binomial nomenclature) is not the same as classification, although the two are related. Classification is the ordering of items into groups based on similarities or differences; in biological classification, species are one of the kinds of item to be classified. In principle, the names given to species could be completely independent of their classification. This is not the case for binomial names, since the first part of a binomial is the name of the genus into which the species is placed. Above the rank of genus, binomial nomenclature and classification are partly independent; for example, a species retains its binomial name if it is moved from one family to another or from one order to another, unless it better fits a different genus in the same or different family, or it is split from its old genus and placed in a newly created genus. The independence is only partial since the names of families and other higher taxa are usually based on genera.

Taxonomy includes both nomenclature and classification. Its first stages (sometimes called "alpha taxonomy") are concerned with finding, describing and naming species of living or fossil organisms. Binomial nomenclature is thus an important part of taxonomy as it is the system by which species are named. Taxonomists are also concerned with classification, including its principles, procedures and rules.

Derivation of binomial names

See also: List of Latin and Greek words commonly used in systematic names

A complete binomial name is always treated grammatically as if it were a phrase in the Latin language (hence the common use of the term "Latin name" for a binomial name). However, the two parts of a binomial name can each be derived from a number of sources, of which Latin is only one. These include:

• Latin, from any period, whether classical, medieval or modern. Thus, both parts of the binomial name Homo sapiens are Latin words, meaning "wise" (sapiens) "human/man" (Homo).
• Classical Greek. The genus Rhododendron was named by Linnaeus from the Greek word ῥοδόδενδρον, itself derived from rhodon, "rose", and dendron, "tree". Greek words are often converted to a Latinized form. Thus coca (the plant from which cocaine is obtained) has the name Erythroxylum coca. Erythroxylum is derived from the Greek words erythros, red, and xylon, wood. The Greek neuter ending -ον (-on) is often converted to the Latin neuter ending -um.
• Other languages. The second part of the name Erythroxylum coca is derived from kuka, the name of the plant in Aymara and Quechua. Since many dinosaur fossils were found in Mongolia, their names often use Mongolian words, e.g. Tarchia from tarkhi, meaning "brain", or Saichania meaning "beautiful one".
• Names of people (often naturalists or biologists). The name Magnolia campbellii commemorates two people: Pierre Magnol, a French botanist, and Archibald Campbell, a doctor in British India.
• Names of places. The lone star tick, Amblyomma americanum, is widespread in the United States.
• Other sources. Some binomial names have been constructed from taxonomic anagrams or other re-orderings of existing names. Thus the name of the genus Muilla is derived by reversing the name Allium. Names may also be derived from jokes or puns. For example, Ratcliffe described a number of species of rhinoceros beetle, including Cyclocephala nodanotherwon.

The first part of the name, which identifies the genus, must be a word which can be treated as a Latin singular noun in the nominative case. It must be unique within the purview of each nomenclatural code, but can be repeated between them. Thus Huia recurvata is an extinct species of plant, found as fossils in Yunnan, China, whereas Huia masonii is a species of frog found in Java, Indonesia.

The second part of the name, which identifies the species within the genus, is also treated grammatically as a Latin word. It can have one of a number of forms:

• The second part of a binomial may be an adjective. The adjective must agree with the genus name in gender. Latin has three genders, masculine, feminine and neuter, shown by varying endings to nouns and adjectives. The house sparrow has the binomial name Passer domesticus. Here domesticus ("domestic") simply means "associated with the house". The sacred bamboo is Nandina domestica rather than Nandina domesticus, since Nandina is feminine whereas Passer is masculine. The tropical fruit langsat is a product of the plant Lansium parasiticum, since Lansium is neuter. Some common endings for Latin adjectives in the three genders (masculine, feminine, neuter) are -us, -a, -um (as in the previous example of domesticus); -is, -is, -e (e.g., tristis, meaning "sad"); and -or -or -us (e.g., minor, meaning "smaller"). For further information, see Latin declension: Adjectives.
• The second part of a binomial may be a noun in the nominative case. An example is the binomial name of the lion, which is Panthera leo. Grammatically the noun is said to be in apposition to the genus name and the two nouns do not have to agree in gender; in this case, Panthera is feminine and leo is masculine.

Magnolia hodgsonii

• The second part of a binomial may be a noun in the genitive (possessive) case. The genitive case is constructed in a number of ways in Latin, depending on the declension of the noun. Common endings for masculine and neuter nouns are -ii or -i in the singular and -orum in the plural, and for feminine nouns -ae in the singular and -arum in the plural. The noun may be part of a person's name, often the surname, as in the Tibetan antelope (Pantholops hodgsonii), the shrub Magnolia hodgsonii, or the olive-backed pipit (Anthus hodgsoni). The meaning is "of the person named", so Magnolia hodgsonii means "Hodgson's magnolia". The -ii or -i endings show that in each case Hodgson was a man (not the same one); had Hodgson been a woman, hodgsonae would have been used. The person commemorated in the binomial name is not usually (if ever) the person who created the name; for example, Anthus hodgsoni was named by Charles Wallace Richmond, in honour of Hodgson. Rather than a person, the noun may be related to a place, as with Latimeria chalumnae, meaning "of the Chalumna River". Another use of genitive nouns is in, for example, the name of the bacterium Escherichia coli, where coli means "of the colon". This formation is common in parasites, as in Xenos vesparum, where vesparum means "of the wasps", since Xenos vesparum is a parasite of wasps.

Whereas the first part of a binomial name must be unique within the purview of each nomenclatural code, the second part is quite commonly used in two or more genera (as is shown by examples of hodgsonii above). The full binomial name must be unique within each code.

Codes

From the early 19th century onwards it became ever more apparent that a body of rules was necessary to govern scientific names. In the course of time these became nomenclature codes. The International Code of Zoological Nomenclature (ICZN) governs the naming of animals, the International Code of Nomenclature for algae, fungi, and plants (ICNafp) that of plants (including cyanobacteria), and the International Code of Nomenclature of Bacteria (ICNB) that of bacteria (including Archaea). Virus names are governed by the International Committee on Taxonomy of Viruses (ICTV), a taxonomic code, which determines taxa as well as names. These codes differ in certain ways, e.g.:

• "Binomial nomenclature" is the correct term for botany, although it is also used by zoologists. Since 1961, "binominal nomenclature" is the technically correct term in zoology. A binomial name is also called a binomen (plural binomina) or binominal name.
• Both codes consider the first part of the two-part name for a species to be the "generic name". In the zoological code (ICZN), the second part of the name is a "specific name". In the botanical code (ICNafp), it is a "specific epithet". Together, these two parts are referred to as a "species name" or "binomen" in the zoological code: or "species name", "binomial", or "binary combination" in the botanical code. "Species name" is the only term common to the two codes.
• The ICNafp, the plant code, does not allow the two parts of a binomial name to be the same (such a name is called a tautonym), whereas the ICZN, the animal code, does. Thus the American bison has the binomen Bison bison; a name of this kind would not be allowed for a plant.
• The starting points, the time from which these codes are in effect (retroactively), vary from group to group. In botany the starting point will often be in 1753 (the year Carl Linnaeus first published Species Plantarum). In zoology the starting point is 1758 (1 January 1758 is considered the date of the publication of Linnaeus's Systema Naturae, 10th Edition, and also Clerck's Aranei Svecici). Bacteriology started anew, with a starting point on 1 January 1980.

Summary of terminology for the names of species in the ICZN and ICNafp

Code	Full name	First part	Second part
ICZN	species name, binomen, binominal name	generic name, genus name	specific name
ICNafp	species name, binary combination, binomial (name)	generic name	specific epithet

Unifying the different codes into a single code, the "BioCode", has been suggested, although implementation is not in sight. (There is also a published code for a different system of biotic nomenclature, which does not use ranks above species, but instead names clades. This is called PhyloCode.)

Differences in handling personal names

As noted above, there are some differences between the codes in how binomials can be formed; for example the ICZN allows both parts to be the same, while the ICNafp does not. Another difference is in how personal names are used in forming specific names or epithets. The ICNafp sets out precise rules by which a personal name is to be converted to a specific epithet. In particular, names ending in a consonant (but not "er") are treated as first being converted into Latin by adding "-ius" (for a man) or "-ia" (for a woman), and then being made genitive (i.e. meaning "of that person or persons"). This produces specific epithets like lecardii for Lecard (male), wilsoniae for Wilson (female), and brauniarum for the Braun sisters. By contrast, the ICZN does not require the intermediate creation of a Latin form of a personal name, allowing the genitive ending to be added directly to the personal name. This explains the difference between the names of the plant Magnolia hodgsonii and the bird Anthus hodgsoni. Furthermore, the ICNafp requires names not published in the form required by the code to be corrected to conform to it, whereas the ICZN is more protective of the form used by the original author.

Writing binomial names

By tradition, the binomial names of species are usually typeset in italics; for example, Homo sapiens. Generally, the binomial should be printed in a font style different from that used in the normal text; for example, "Several more Homo sapiens fossils were discovered." When handwritten, a binomial name should be underlined; for example, Homo sapiens.

The first part of the binomial, the genus name, is always written with an initial capital letter. Older sources, particularly botanical works published before the 1950s, used a different convention: if the second part of the name was derived from a proper noun, e.g., the name of a person or place, a capital letter was used. Thus, the modern form Berberis darwinii was written as Berberis Darwinii. A capital was also used when the name is formed by two nouns in apposition, e.g., Panthera Leo or Centaurea Cyanus. In current usage, the second part is never written with an initial capital.

When used with a common name, the scientific name often follows in parentheses, although this varies with publication. For example, "The house sparrow (Passer domesticus) is decreasing in Europe."

The binomial name should generally be written in full. The exception to this is when several species from the same genus are being listed or discussed in the same paper or report, or the same species is mentioned repeatedly; in which case the genus is written in full when it is first used, but may then be abbreviated to an initial (and a period/full stop). For example, a list of members of the genus Canis might be written as "Canis lupus, C. aureus, C. simensis". In rare cases, this abbreviated form has spread to more general use; for example, the bacterium Escherichia coli is often referred to as just E. coli, and Tyrannosaurus rex is perhaps even better known simply as T. rex, these two both often appearing in this form in popular writing even where the full genus name has not already been given.

The abbreviation "sp." is used when the actual specific name cannot or need not be specified. The abbreviation "spp." (plural) indicates "several species". These abbreviations are not italicised (or underlined). For example: "Canis sp." means "an unspecified species of the genus Canis", while "Canis spp." means "two or more species of the genus Canis". (These abbreviations should not be confused with the abbreviations "ssp." (zoology) or "subsp." (botany), plurals "sspp." or "subspp.", referring to one or more subspecies. See trinomen (zoology) and infraspecific name.)

The abbreviation "cf." (i.e., confer in Latin) is used to compare individuals/taxa with known/described species. Conventions for use of the "cf." qualifier vary. In paleontology, it is typically used when the identification is not confirmed. For example, "Corvus cf. nasicus" was used to indicate "a fossil bird similar to the Cuban crow but not certainly identified as this species". In molecular systematics papers, "cf." may be used to indicate one or more undescribed species assumed to be related to a described species. For example, in a paper describing the phylogeny of small benthic freshwater fish called darters, five undescribed putative species (Ozark, Sheltowee, Wildcat, Ihiyo, and Mamequit darters), notable for brightly colored nuptial males with distinctive color patterns, were referred to as "Etheostoma cf. spectabile" because they had been viewed as related to, but distinct from, Etheostoma spectabile (orangethroat darter). This view was supported to varying degrees by DNA analysis. The somewhat informal use of taxa names with qualifying abbreviations is referred to as open nomenclature and it is not subject to strict usage codes.

In some contexts, the dagger symbol ("†") may be used before or after the binomial name to indicate that the species is extinct.

Authority

Main articles: Author citation (zoology) and Author citation (botany)

In scholarly texts, at least the first or main use of the binomial name is usually followed by the "authority" – a way of designating the scientist(s) who first published the name. The authority is written in slightly different ways in zoology and botany. For names governed by the ICZN the surname is usually written in full together with the date (normally only the year) of publication. One example of author citation of scientific name is: "Amabela Möschler, 1880." The ICZN recommends that the "original author and date of a name should be cited at least once in each work dealing with the taxon denoted by that name." For names governed by the ICNafp the name is generally reduced to a standard abbreviation and the date omitted. The International Plant Names Index maintains an approved list of botanical author abbreviations. Historically, abbreviations were used in zoology too.

When the original name is changed, e.g., the species is moved to a different genus, both codes use parentheses around the original authority; the ICNafp also requires the person who made the change to be given. In the ICNafp, the original name is then called the basionym. Some examples:

• (Plant) Amaranthus retroflexus L. – "L." is the standard abbreviation for "Linnaeus"; the absence of parentheses shows that this is his original name.
• (Plant) Hyacinthoides italica (L.) Rothm. – Linnaeus first named the Italian bluebell Scilla italica; that is the basionym. Rothmaler later transferred it to the genus Hyacinthoides.
• (Animal) Passer domesticus (Linnaeus, 1758) – the original name given by Linnaeus was Fringilla domestica; unlike the ICNafp, the ICZN does not require the name of the person who changed the genus (Mathurin Jacques Brisson) to be given.

Other ranks

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Main articles: Biological nomenclature, Trinomial nomenclature, and Infraspecific name (botany)

Binomial nomenclature, as described here, is a system for naming species. Implicitly, it includes a system for naming genera, since the first part of the name of the species is a genus name. In a classification system based on ranks, there are also ways of naming ranks above the level of genus and below the level of species. Ranks above genus (e.g., family, order, class) receive one-part names, which are conventionally not written in italics. Thus, the house sparrow, Passer domesticus, belongs to the family Passeridae. Family names are normally based on genus names, although the endings used differ between zoology and botany.

Ranks below species receive three-part names, conventionally written in italics like the names of species. There are significant differences between the ICZN and the ICNafp. In zoology, the only rank below species is subspecies and the name is written simply as three parts (a trinomen). Thus, one of the subspecies of the olive-backed pipit is Anthus hodgsoni berezowskii. In botany, there are many ranks below species and although the name itself is written in three parts, a "connecting term" (not part of the name) is needed to show the rank. Thus, the American black elder is Sambucus nigra subsp. canadensis; the white-flowered form of the ivy-leaved cyclamen is Cyclamen hederifolium f. albiflorum.