Photonic crystal

From Wikipedia, the free encyclopedia

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

 

The opal in this bracelet contains a natural periodic microstructure responsible for its iridescent color. It is essentially a natural photonic crystal.

 

Wings of some butterflies contain photonic crystals.

A photonic crystal is an optical nanostructure in which the refractive index changes periodically. This affects the propagation of light in the same way that the structure of natural crystals gives rise to X-ray diffraction and that the atomic lattices (crystal structure) of semiconductors affect their conductivity of electrons. Photonic crystals occur in nature in the form of structural coloration and animal reflectors, and, as artificially produced, promise to be useful in a range of applications.

Photonic crystals can be fabricated for one, two, or three dimensions. One-dimensional photonic crystals can be made of thin film layers deposited on each other. Two-dimensional ones can be made by photolithography, or by drilling holes in a suitable substrate. Fabrication methods for three-dimensional ones include drilling under different angles, stacking multiple 2-D layers on top of each other, direct laser writing, or, for example, instigating self-assembly of spheres in a matrix and dissolving the spheres.

Photonic crystals can, in principle, find uses wherever light must be manipulated. For example, dielectric mirrors are one-dimensional photonic crystals which can produce ultra-high reflectivity mirrors at a specified wavelength. Two-dimensional photonic crystals called photonic-crystal fibers are used for fiber-optic communication, among other applications. Three-dimensional crystals may one day be used in optical computers, and could lead to more efficient photovoltaic cells.

Although the energy of light (and all electromagnetic radiation) is quantized in units called photons, the analysis of photonic crystals requires only classical physics. "Photonic" in the name is a reference to photonics, a modern designation for the study of light (optics) and optical engineering. Indeed, the first research into what we now call photonic crystals may have been as early as 1887 when the English physicist Lord Rayleigh experimented with periodic multi-layer dielectric stacks, showing they can effect a photonic band-gap in one dimension. Research interest grew with work in 1987 by Eli Yablonovitch and Sajeev John on periodic optical structures with more than one dimension—now called photonic crystals.

Introduction

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Diffraction from a periodic structure as a function of incident wavelength. For some wavelength ranges, the wave is unable to penetrate the structure.

Photonic crystals are composed of periodic dielectric, metallo-dielectric—or even superconductor microstructures or nanostructures that affect electromagnetic wave propagation in the same way that the periodic potential in a semiconductor crystal affects the propagation of electrons, determining allowed and forbidden electronic energy bands. Photonic crystals contain regularly repeating regions of high and low refractive index. Light waves may propagate through this structure or propagation may be disallowed, depending on their wavelength. Wavelengths that may propagate in a given direction are called modes, and the ranges of wavelengths which propagate are called bands. Disallowed bands of wavelengths are called photonic band gaps. This gives rise to distinct optical phenomena, such as inhibition of spontaneous emission, high-reflecting omni-directional mirrors, and low-loss-waveguiding. The bandgap of photonic crystals can be understood as the destructive interference of multiple reflections of light propagating in the crystal at each interface between layers of high- and low- refractive index regions, akin to the bandgaps of electrons in solids.

The periodicity of the photonic crystal structure must be around or greater than half the wavelength (in the medium) of the light waves in order for interference effects to be exhibited. Visible light ranges in wavelength between about 400 nm (violet) to about 700 nm (red) and the resulting wavelength inside a material requires dividing that by the average index of refraction. The repeating regions of high and low dielectric constant must, therefore, be fabricated at this scale. In one dimension, this is routinely accomplished using the techniques of thin-film deposition.

History

Photonic crystals have been studied in one form or another since 1887, but no one used the term photonic crystal until over 100 years later—after Eli Yablonovitch and Sajeev John published two milestone papers on photonic crystals in 1987. The early history is well-documented in the form of a story when it was identified as one of the landmark developments in physics by the American Physical Society.

Before 1987, one-dimensional photonic crystals in the form of periodic multi-layer dielectric stacks (such as the Bragg mirror) were studied extensively. Lord Rayleigh started their study in 1887, by showing that such systems have a one-dimensional photonic band-gap, a spectral range of large reflectivity, known as a stop-band. Today, such structures are used in a diverse range of applications—from reflective coatings to enhancing LED efficiency to highly reflective mirrors in certain laser cavities (see, for example, VCSEL). The pass-bands and stop-bands in photonic crystals were first reduced to practice by Melvin M. Weiner who called those crystals "discrete phase-ordered media." Melvin M. Weiner achieved those results by extending Darwin's dynamical theory for x-ray Bragg diffraction to arbitrary wavelengths, angles of incidence, and cases where the incident wavefront at a lattice plane is scattered appreciably in the forward-scattered direction. A detailed theoretical study of one-dimensional optical structures was performed by Vladimir P. Bykov, who was the first to investigate the effect of a photonic band-gap on the spontaneous emission from atoms and molecules embedded within the photonic structure. Bykov also speculated as to what could happen if two- or three-dimensional periodic optical structures were used. The concept of three-dimensional photonic crystals was then discussed by Ohtaka in 1979, who also developed a formalism for the calculation of the photonic band structure. However, these ideas did not take off until after the publication of two milestone papers in 1987 by Yablonovitch and John. Both these papers concerned high-dimensional periodic optical structures, i.e., photonic crystals. Yablonovitch's main goal was to engineer photonic density of states to control the spontaneous emission of materials embedded in the photonic crystal. John's idea was to use photonic crystals to affect localisation and control of light.

After 1987, the number of research papers concerning photonic crystals began to grow exponentially. However, due to the difficulty of fabricating these structures at optical scales (see Fabrication challenges), early studies were either theoretical or in the microwave regime, where photonic crystals can be built on the more accessible centimetre scale. (This fact is due to a property of the electromagnetic fields known as scale invariance. In essence, electromagnetic fields, as the solutions to Maxwell's equations, have no natural length scale—so solutions for centimetre scale structure at microwave frequencies are the same as for nanometre scale structures at optical frequencies.)

By 1991, Yablonovitch had demonstrated the first three-dimensional photonic band-gap in the microwave regime. The structure that Yablonovitch was able to produce involved drilling an array of holes in a transparent material, where the holes of each layer form an inverse diamond structure – today it is known as Yablonovite.

In 1996, Thomas Krauss demonstrated a two-dimensional photonic crystal at optical wavelengths. This opened the way to fabricate photonic crystals in semiconductor materials by borrowing methods from the semiconductor industry.

Today, such techniques use photonic crystal slabs, which are two dimensional photonic crystals "etched" into slabs of semiconductor. Total internal reflection confines light to the slab, and allows photonic crystal effects, such as engineering photonic dispersion in the slab. Researchers around the world are looking for ways to use photonic crystal slabs in integrated computer chips, to improve optical processing of communications—both on-chip and between chips.

Autocloning fabrication technique, proposed for infrared and visible range photonic crystals by Sato et al. in 2002, utilizes electron-beam lithography and dry etching: lithographically-formed layers of periodic grooves are stacked by regulated sputter deposition and etching, resulting in "stationary corrugations" and periodicity. Titanium dioxide/silica and tantalum pentoxide/silica devices were produced, exploiting their dispersion characteristics and suitability to sputter deposition.

Such techniques have yet to mature into commercial applications, but two-dimensional photonic crystals are commercially used in photonic crystal fibres (otherwise known as holey fibres, because of the air holes that run through them). Photonic crystal fibres were first developed by Philip Russell in 1998, and can be designed to possess enhanced properties over (normal) optical fibres.

Study has proceeded more slowly in three-dimensional than in two-dimensional photonic crystals. This is because of more difficult fabrication. Three-dimensional photonic crystal fabrication had no inheritable semiconductor industry techniques to draw on. Attempts have been made, however, to adapt some of the same techniques, and quite advanced examples have been demonstrated, for example in the construction of "woodpile" structures constructed on a planar layer-by-layer basis. Another strand of research has tried to construct three-dimensional photonic structures from self-assembly—essentially letting a mixture of dielectric nano-spheres settle from solution into three-dimensionally periodic structures that have photonic band-gaps. Vasily Astratov's group from the Ioffe Institute realized in 1995 that natural and synthetic opals are photonic crystals with an incomplete bandgap. The first demonstration of an "inverse opal" structure with a complete photonic bandgap came in 2000, from researchers at the University of Toronto, Canada, and Institute of Materials Science of Madrid (ICMM-CSIC), Spain. The ever-expanding field of natural photonics, bioinspiration and biomimetics—the study of natural structures to better understand and use them in design—is also helping researchers in photonic crystals. For example, in 2006 a naturally occurring photonic crystal was discovered in the scales of a Brazilian beetle. Analogously, in 2012 a diamond crystal structure was found in a weevil and a gyroid-type architecture in a butterfly. More recently, gyroid photonic crystals have been found in the feather barbs of blue-winged leafbirds and are responsible for the bird's shimmery blue coloration.

Construction strategies

The fabrication method depends on the number of dimensions that the photonic bandgap must exist in.

• Examples of possible photonic crystal structures in 1, 2 and 3 dimensions
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  Comparison of 1D, 2D and 3D photonic crystal structures (from left to right, respectively).

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  Schematic of a 1D photonic crystal structure, made of alternating layers of a high-dielectric constant material and a low-dielectric constant material. These layers are typically quarter wavelength in thickness.

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  2D photonic crystal structure in a square array.

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  Schematic of a 2D photonic crystal made of circular holes.

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  A woodpile structured 3D photonic crystal. These structures have a three-dimensional bandgap for all polarizations

One-dimensional photonic crystals

To produce a one-dimensional photonic crystal, thin film layers of different dielectric constant may be periodically deposited on a surface which leads to a band gap in a particular propagation direction (such as normal to the surface). A Bragg grating is an example of this type of photonic crystal. One-dimensional photonic crystals can include layers of non-linear optical materials in which the non-linear behaviour is accentuated due to field enhancement at wavelengths near a so-called degenerate band edge. This field enhancement (in terms of intensity) can reach ${\displaystyle N^{2}}$ where N is the total number of layers. However by using layers which include an optically anisotropic material, it has been shown that the field enhancement can reach ${\displaystyle N^{4}}$, which, in conjunction with non-linear optics, has potential applications such as in the development of an all-optical switch.

A one-dimensional photonic crystal can be implemented using repeated alternating layers of a metamaterial and vacuum. If the metamaterial is such that the relative permittivity and permeability follow the same wavelength dependence, then the photonic crystal behaves identically for TE and TM modes, that is, for both s and p polarizations of light incident at an angle.

Recently, researchers fabricated a graphene-based Bragg grating (one-dimensional photonic crystal) and demonstrated that it supports excitation of surface electromagnetic waves in the periodic structure by using 633 nm He-Ne laser as the light source. Besides, a novel type of one-dimensional graphene-dielectric photonic crystal has also been proposed. This structure can act as a far-IR filter and can support low-loss surface plasmons for waveguide and sensing applications. 1D photonic crystals doped with bio-active metals (i.e. silver) have been also proposed as sensing devices for bacterial contaminants. Similar planar 1D photonic crystals made of polymers have been used to detect volatile organic compounds vapors in atmosphere. In addition to solid-phase photonic crystals, some liquid crystals with defined ordering can demonstrate photonic color. For example, studies have shown several liquid crystals with short- or long-range one-dimensional positional ordering can form photonic structures.

Two-dimensional photonic crystals

In two dimensions, holes may be drilled in a substrate that is transparent to the wavelength of radiation that the bandgap is designed to block. Triangular and square lattices of holes have been successfully employed.

The Holey fiber or photonic crystal fiber can be made by taking cylindrical rods of glass in hexagonal lattice, and then heating and stretching them, the triangle-like airgaps between the glass rods become the holes that confine the modes.

Three-dimensional photonic crystals

There are several structure types that have been constructed:

• Spheres in a diamond lattice
• Yablonovite
• The woodpile structure – "rods" are repeatedly etched with beam lithography, filled in, and covered with a layer of new material. As the process repeats, the channels etched in each layer are perpendicular to the layer below, and parallel to and out of phase with the channels two layers below. The process repeats until the structure is of the desired height. The fill-in material is then dissolved using an agent that dissolves the fill-in material but not the deposition material. It is generally hard to introduce defects into this structure.
• Inverse opals or Inverse Colloidal Crystals-Spheres (such as polystyrene or silicon dioxide) can be allowed to deposit into a cubic close packed lattice suspended in a solvent. Then a hardener is introduced that makes a transparent solid out of the volume occupied by the solvent. The spheres are then dissolved with an acid such as Hydrochloric acid. The colloids can be either spherical or nonspherical. contains in excess of 750,000 polymer nanorods. Light focused on this beam splitter penetrates or is reflected, depending on polarization.

A photonic crystal fiber. SEM images of US NRL-produced fiber. (left) The diameter of the solid core at the center of the fiber is 5 µm, while (right) the diameter of the holes is 4 µm. Source: http://www.nrl.navy.mil/techtransfer/fs.php?fs_id=97

 

An SEM image of a self-assembled PMMA photonic crystal in two dimensions

Photonic crystal cavities

Not only band gap, photonic crystals may have another effect if we partially remove the symmetry through the creation a nanosize cavity. This defect allows you to guide or to trap the light with the same function as nanophotonic resonator and it is characterized by the strong dielectric modulation in the photonic crystals. For the waveguide, the propagation of light depends on the in-plane control provided by the photonic band gap and to the long confinement of light induced by dielectric mismatch. For the light trap, the light is strongly confined in the cavity resulting further interactions with the materials. First, if we put a pulse of light inside the cavity, it will be delayed by nano- or picoseconds and this is proportional to the quality factor of the cavity. Finally, if we put an emitter inside the cavity, the emission light also can be enhanced significantly and or even the resonant coupling can go through Rabi oscillation. This is related with cavity quantum electrodynamics and the interactions are defined by the weak and strong coupling of the emitter and the cavity. The first studies for the cavity in one-dimensional photonic slabs are usually in grating or distributed feedback structures. For two-dimensional photonic crystal cavities, they are useful to make efficient photonic devices in telecommunication applications as they can provide very high quality factor up to millions with smaller-than-wavelength mode volume. For three-dimensional photonic crystal cavities, several methods have been developed including lithographic layer-by-layer approach, surface ion beam lithography, and micromanipulation technique. All those mentioned photonic crystal cavities that tightly confine light offer very useful functionality for integrated photonic circuits, but it is challenging to produce them in a manner that allows them to be easily relocated. There is no full control with the cavity creation, the cavity location, and the emitter position relative to the maximum field of the cavity while the studies to solve those problems are still ongoing. Movable cavity of nanowire in photonic crystals is one of solutions to tailor this light matter interaction.

Fabrication challenges

Higher-dimensional photonic crystal fabrication faces two major challenges:

• Making them with enough precision to prevent scattering losses blurring the crystal properties
• Designing processes that can robustly mass-produce the crystals

One promising fabrication method for two-dimensionally periodic photonic crystals is a photonic-crystal fiber, such as a holey fiber. Using fiber draw techniques developed for communications fiber it meets these two requirements, and photonic crystal fibres are commercially available. Another promising method for developing two-dimensional photonic crystals is the so-called photonic crystal slab. These structures consist of a slab of material—such as silicon—that can be patterned using techniques from the semiconductor industry. Such chips offer the potential to combine photonic processing with electronic processing on a single chip.

For three dimensional photonic crystals, various techniques have been used—including photolithography and etching techniques similar to those used for integrated circuits. Some of these techniques are already commercially available. To avoid the complex machinery of nanotechnological methods, some alternate approaches involve growing photonic crystals from colloidal crystals as self-assembled structures.

Mass-scale 3D photonic crystal films and fibres can now be produced using a shear-assembly technique that stacks 200–300 nm colloidal polymer spheres into perfect films of fcc lattice. Because the particles have a softer transparent rubber coating, the films can be stretched and molded, tuning the photonic bandgaps and producing striking structural color effects.

Computing photonic band structure

The photonic band gap (PBG) is essentially the gap between the air-line and the dielectric-line in the dispersion relation of the PBG system. To design photonic crystal systems, it is essential to engineer the location and size of the bandgap by computational modeling using any of the following methods:

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A video simulation of scattering forces and fields in a photonic crystal structure

• Plane wave expansion method
• Finite element method
• Finite difference time domain method
• Order-n spectral method
• KKR method
• Bloch wave – MoM method

Essentially, these methods solve for the frequencies (normal modes) of the photonic crystal for each value of the propagation direction given by the wave vector, or vice versa. The various lines in the band structure, correspond to the different cases of n, the band index. For an introduction to photonic band structure, see K. Sakoda's  and Joannopoulos  books.

Band structure of a 1D photonic crystal, DBR air-core calculated using plane wave expansion technique with 101 planewaves, for d/a=0.8, and dielectric contrast of 12.250.

The plane wave expansion method can be used to calculate the band structure using an eigen formulation of the Maxwell's equations, and thus solving for the eigen frequencies for each of the propagation directions, of the wave vectors. It directly solves for the dispersion diagram. Electric field strength values can also be calculated over the spatial domain of the problem using the eigen vectors of the same problem. For the picture shown to the right, corresponds to the band-structure of a 1D distributed Bragg reflector (DBR) with air-core interleaved with a dielectric material of relative permittivity 12.25, and a lattice period to air-core thickness ratio (d/a) of 0.8, is solved using 101 planewaves over the first irreducible Brillouin zone.

To speed calculation of the frequency band structure, the Reduced Bloch Mode Expansion (RBME) method can be used. The RBME method applies "on top" of any of the primary expansion methods mentioned above. For large unit cell models, the RBME method can reduce time for computing the band structure by up to two orders of magnitude.

Applications

See also: Photonic crystal sensor

Photonic crystals are attractive optical materials for controlling and manipulating light flow. One dimensional photonic crystals are already in widespread use, in the form of thin-film optics, with applications from low and high reflection coatings on lenses and mirrors to colour changing paints and inks. Higher-dimensional photonic crystals are of great interest for both fundamental and applied research, and the two dimensional ones are beginning to find commercial applications.

The first commercial products involving two-dimensionally periodic photonic crystals are already available in the form of photonic-crystal fibers, which use a microscale structure to confine light with radically different characteristics compared to conventional optical fiber for applications in nonlinear devices and guiding exotic wavelengths. The three-dimensional counterparts are still far from commercialization but may offer additional features such as optical nonlinearity required for the operation of optical transistors used in optical computers, when some technological aspects such as manufacturability and principal difficulties such as disorder are under control.

In addition to the foregoing, photonic crystals have been proposed as platforms for the development of solar cells and optical sensors, including chemical sensors and biosensors.

Frailty syndrome

From Wikipedia, the free encyclopedia

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

 

Frailty syndrome
A woman supporting herself with a walking frame.
Specialty	Geriatrics

Frailty is a common geriatric syndrome that embodies an elevated risk of catastrophic declines in health and function among older adults. Frailty is a condition associated with ageing, and it has been recognized for centuries. It is also a marker of a more widespread syndrome of frailty, with associated weakness, slowing, decreased energy, lower activity, and, when severe, unintended weight loss. Frailty has been identified as a risk factor for the development of dementia.

As a population ages, a central focus of geriatricians and public health practitioners is to understand, and then beneficially intervene on, the factors and processes that put elders at such risk, especially the increased vulnerability to stressors (e.g. extremes of heat and cold, infection, injury, or even changes in medication) that characterizes many older adults.

Geriatric syndromes related to frailty

Sarcopenia

Sarcopenia is the degenerative loss of skeletal muscle mass, quality, and strength associated with aging. The rate of muscle loss is dependent on exercise level, co-morbidities, nutrition and other factors. Sarcopenia can lead to reduction in functional status and cause significant disability from increased weakness. The muscle loss is related to changes in muscle synthesis signalling pathways although is incompletely understood. The cellular mechanisms are distinct from other types of muscle atrophy such as cachexia, in which muscle is degraded through cytokine-mediated degradation although both conditions may co-exist.

Osteoporosis

Osteoporosis causes a hunched-over appearance in some people.

Osteoporosis is an age-related disease of bone that leads to an increased risk of fracture. In osteoporosis the bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of proteins in bone is altered. Osteoporosis is defined by the World Health Organization (WHO) in women as a bone mineral density 2.5 standard deviations below peak bone mass (20-year-old healthy female average) as measured by DXA; the term "established osteoporosis" includes the presence of a fragility fracture.

Osteoporosis is most common in women after menopause, when it is called postmenopausal osteoporosis, but may also develop in men, and may occur in anyone in the presence of particular hormonal disorders and other chronic diseases or as a result of medications, specifically glucocorticoids, when the disease is called steroid- or glucocorticoid-induced osteoporosis (SIOP or GIOP). Given its influence in the risk of fragility fracture, osteoporosis may significantly affect life expectancy and quality of life.

Muscle weakness

Muscle weakness, also known as muscle fatigue, (or "lack of strength") refers to the inability to exert force with one's skeletal muscles. Weakness often follows muscle atrophy and a decrease in activity, such as after a long bout of bedrest as a result of an illness. There is also a gradual onset of muscle weakness as a result of sarcopenia – the age-related loss of skeletal muscle.

Muscle weakness makes it difficult to perform everyday activities, like getting into a bathtub.

A test of strength is often used during a diagnosis of a muscular disorder before the etiology can be identified. Such etiology depends on the type of muscle weakness, which can be true or perceived as well as variable topically. True weakness is substantial, while perceived rather is a sensation of having to put more effort to do the same task. On the other hand, various topic locations for muscle weakness are central, neural and peripheral. Central muscle weakness is an overall exhaustion of the whole body, while peripheral weakness is an exhaustion of individual muscles. Neural weakness is somewhere between.

Biological and physiological mechanisms

It has been suggested that the causes of frailty are multifactorial, involving dysregulation across many physiological systems. A proinflammatory state, sarcopenia, anemia, relative deficiencies in anabolic hormones (androgens and growth hormone) and excess exposure to catabolic hormones (cortisol), insulin resistance, glucose levels, compromised altered immune function, micronutrient deficiencies and oxidative stress are each individually associated with a higher likelihood of frailty. Additional findings show that the risk of frailty increases with an increased number of abnormal bodily systems. This finding shows that interventions that target multiple systems may yield greater results in prevention and treatment of frailty than interventions that target only one system.

Associations between specific disease states are also associated with and frailty have also been observed, including cardiovascular disease, diabetes mellitus, chronic kidney disease and other diseases in which inflammation is prominent. It is possible that clinically measurable disease states can manifest themselves or be captured prior to the onset of frailty. No single disease state is necessary and sufficient for the pathogenesis of frailty, since many individuals with chronic diseases are not frail. Therefore, rather than being dependent on the presence of measurable diseases, frailty is an expression of a critical mass of physiologic impairments. Frailty has been identified as a risk factor for the development of dementia.

Theoretical understanding

Recent work on frailty has sought to characterize both the underlying changes in the body and the manifestations that make frailty recognizable. It is well-agreed upon that declines in physiologic reserves and resilience is the essence of being frail. Similarly, scientists agree that the risk of frailty increases with age and with the incidence of diseases. Beyond that, there is now strong evidence to support the theory that the development of frailty involves declines in energy production, energy utilization and repair systems in the body, resulting in declines in the function of many different physiological systems. This decline in multiple systems affects the normal complex adaptive behavior that is essential to health and eventually results in frailty typically manifesting as a syndrome of a constellation of weakness, slowness, reduced activity, low energy and unintended weight loss. When most severe, i.e. when 3 or more of these manifestations are present, the individual is at a high risk of death.

Frailty assessment

Further information: Frailty index and Physiological functional capacity

The syndrome of geriatric frailty is hypothesized to reflect impairments in the regulation of multiple physiologic systems, embodying a lack of resilience to physiologic challenges and thus elevated risk for a range of deleterious endpoints. Generally speaking, the empirical assessment of geriatric frailty in individuals seeks ultimately to capture this or related features, though distinct approaches to such assessment have been developed in the literature (see de Vries et al., 2011 for a comprehensive review).

Two most widely used approaches, different in their nature and scopes, are discussed below. Other approaches follow.

Physical frailty phenotype

A popular approach to the assessment of geriatric frailty encompasses the assessment of five dimensions that are hypothesized to reflect systems whose impaired regulation underlies the syndrome. These five dimensions are:

• unintentional weight loss,
• exhaustion,
• muscle weakness,
• slowness while walking, and
• low levels of activity.

Corresponding to these dimensions are five specific criteria indicating adverse functioning, which are implemented using a combination of self-reported and performance-based measures. Those who meet at least three of the criteria are defined as "frail", while those not matching any of the five criteria are defined as "robust". Additional work on the construct is done by Bandeen-Roche et al. (2006), though some of the exact criteria and measures differ (see Table 1 in the paper for this contrast). Other studies in the literature have also adopted the general approach of Linda P. Fried et al. (2001) though, again, the exact criteria and their particular measures may vary. This assessment approach was developed and refined by Fried and colleagues at the Johns Hopkins University's Center on Aging and Health. This center is home to Johns Hopkins Claude D. Pepper Older Americans Independence Center, which focuses on frailty research and has launched a website dedicated to frailty science: https://frailtyscience.org.

Frailty index / Deficit accumulation

Another notable approach to the assessment of geriatric frailty (if not also to some degree its conceptualization) is that of Rockwood and Mitnitski (2007) in which frailty is viewed in terms of the number of health "deficits" that are manifest in the individual, leading to a continuous measure of frailty (see Rockwood, Andrew, and Mitnitski (2007) for a contrast of the two approaches). This approach was developed by Dr. Rockwood and colleagues at Dalhousie University.

Four domains of frailty

A four domains of frailty model was proposed in response to an article in the BMJ. This conceptualisation could be viewed as blending the phenotypic and index models. Researchers tested this model for signal in routinely collected hospital data, and then used this signal in the development of a frailty model, finding even predictive capability across 3 outcomes of care. In the care home setting, one study indicated that not all four domains of frailty were routinely assessed in residents, giving evidence to suggest that frailty may still primarily be viewed only in terms of physical health.

SHARE Frailty Index

The SHARE-Frailty Index (SHARE-FI) was originally developed by Romero-Ortuno (2010) and researchers as part of the Survey of Healthy Ageing and Retirement in Europe. It consists of five domains of the frailty phenotype: •Fatigue •Loss of appetite •Grip strength •Functional difficulties •Physical activity

The SHARE-FI calculator is freely available to use online. The calculator classifies individuals as 1) frail; 2) pre-frail; and 3) non-frail / robust. The SHARE-FI has good clinical utility as it provides relatively quick assessment of frailty in often time-poor healthcare settings.

Prevention

Identification of risk factors

When considering prevention of frailty, it is important to understand the risk factors that contribute to frailty and identify them early on. A 2005 observational study found associations between frailty and a number of risk factors such as: low income, advanced age, chronic medical conditions, lack of education, and smoking.

Exercise

A significant target in the prevention of frailty is physical activity. As people age, physical activity markedly drops, with the steepest declines seen in adolescence and continuing on throughout life. The lower levels of physical activity and are associated with and a key component of frailty syndrome. Therefore, exercise regimens have been examined in a number of studies as an intervention to prevent frailty. A randomized control trial published in 2017 found significantly lower rates of frailty in older adults who were assigned an exercise regimen vs those who were in the control group. In this study, 15.3% of the control group became frail in the time frame of the study, in comparison to 4.9% of the exercise group. The exercise group also received a nutritional assessment, which is another target in frailty prevention.

Nutrition

Nutrition has also been a major target in the prevention of physical activity. A 2019 review paper examined a variety of studies and found evidence of nutritional intervention as an effective way of preventing frailty. With the mediterranean diet in particular reducing risk of frailty up to 60%.

Non-surgical management

Exercise

Individuals partaking in exercise appear to have potential in preventing frailty. In 2018, a systemic review concluded that group exercise had the benefit of delaying frailty in older adults aged 65 and above. Elderly adults are also less likely to sustain fall injuries.

Occupational therapy

Activities of daily living (ADLs) include activities that are necessary to sustain life. Examples are brushing teeth, getting out of bed, dressing oneself, bathing, etc. Occupational therapy provided modest improvements in elderly adults mobility to do ADLs.

Nutritional supplementation

Frailty can involve changes such as weight loss. Interventions should focus on any difficulties with supplementation and diet. For those who may be undernourished and not acquiring adequate calories, oral nutritional supplements in between meals may decrease nutritional deficits.

With age comes decreased bone density. Therefore, vitamin D supplementation may provide the benefits of improving stability and muscle strength retention.

Palliative care

Palliative care may be helpful for individuals who are experiencing an advanced state of frailty with possible other co-morbidities. Improving quality of life by reducing pain and other harmful symptoms is the goal with palliative care. One study showed the cost reduction by focusing on palliative care rather than expensive treatments that may be unnecessary and unhelpful.

Surgical outcomes

Frail elderly people are at significant risk of post-surgical complications and the need for extended care. Frailty more than doubles the risk of morbidity and mortality from surgery and cardiovascular conditions. Assessment of older patients before elective surgeries can accurately predict the patients' recovery trajectories. The most widely used frailty scale consists of five items:

• unintentional weight loss >4.5 kg in the past year
• self-reported exhaustion
• <20th population percentile for grip strength
• slowed walking speed, defined as lowest population quartile on 4-minute walking test
• low physical activity such that persons would only rarely undertake a short walk

A healthy person scores 0; a very frail person scores 5. Compared to non-frail elderly people, people with intermediate frailty scores (2 or 3) are twice as likely to have post-surgical complications, spend 50% more time in the hospital, and are three times as likely to be discharged to a skilled nursing facility instead of to their own homes. Frail elderly patients (score of 4 or 5) have even worse outcomes, with the risk of being discharged to a nursing home rising to twenty times the rate for non-frail elderly people.

Epidemiology and public health

Frailty is a common geriatric syndrome. Estimates of frailty prevalence in older populations may vary according to a number of factors, including the setting in which the prevalence is being estimated – e.g., nursing home (higher prevalence) vs. community (lower prevalence) – and the operational definition used for defining frailty. Using the widely used frailty phenotype framework proposed by Fried et al. (2001), prevalence estimates of 7–16% have been reported in non-institutionalized, community-dwelling older adults.

The occurrence of frailty increases incrementally with advancing age, is more common in older women than men, and among those of lower socio-economic status. Frail older adults are at high risk for major adverse health outcomes, including disability, falls, institutionalization, hospitalization, and mortality.

Epidemiologic research to date has led to the identification of a number of risk factors for frailty, including: (a) chronic diseases, such as cardiovascular disease, diabetes, chronic kidney disease, depression, and cognitive impairment; (b) physiologic impairments, such as activation of inflammation and coagulation systems, anemia, atherosclerosis, autonomic dysfunction, hormonal abnormalities, obesity, hypovitaminosis D in men, and environment-related factors such as life space and neighborhood characteristics. Advances about potentially modifiable risk factors for frailty now offer the basis for translational research effort aimed at prevention and treatment of frailty in older adults. A recent systematic review found that exercise interventions can increase muscle strength and improve physical function; however, results are inconsistent in frail older adults living in the community.

A review looked at the relationship between the frailty syndrome and chronic lower extremity ischemia in those people with diabetes. On the one hand, chronic lower limb ischemia may predispose to the development of frailty, on the other hand, the presence of the frailty may affect the prognosis in patients with peripheral arterial disease.

Ongoing clinical trials

As of September 2021, ongoing clinical trials on frailty syndrome in the US include:

• the impact of frailty on clinical outcomes of patients treated for abdominal aortic aneurysms
• the use of "pre-habilitation," an exercise regimen used before transplant surgery, to prevent the frailty effects of kidney transplant in recipients
• defining the acute changes in frailty following sepsis in the abdomen
• the efficacy of the anti-inflammatory drug, Fisetin, in reducing frailty markers in elderly adults

Up-to-date information on ongoing clinical trials on frailty syndrome and other conditions can be found at clinicaltrials.gov.

Concentration of media ownership

From Wikipedia, the free encyclopedia

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

Media graphic showing the concentration of media ownership in the United States

Concentration of media ownership (also known as media consolidation or media convergence) is a process whereby progressively fewer individuals or organizations control increasing shares of the mass media. Contemporary research demonstrates increasing levels of consolidation, with many media industries already highly concentrated and dominated by a very small number of firms.

Globally, large media conglomerates include Bertelsmann, National Amusements (Paramount Global), Sony Group Corporation, News Corp, Comcast, The Walt Disney Company, Warner Bros. Discovery, Fox Corporation, Hearst Communications, MGM Holdings Inc., Grupo Globo (South America), and Lagardère Group.

As of 2022, the largest media conglomerates in terms of revenue are Comcast, The Walt Disney Company, Warner Bros. Discovery, and Paramount Global.

Mergers

Media mergers occur when one media company buys another. The current landscape of corporate media ownership in the United States of America can be described as an oligopoly.

Risks for media integrity

Media integrity is at risk when small number of companies and individuals control the media market. Media integrity refers to the ability of a media outlet to serve the public interest and democratic process, making it resilient to institutional corruption within the media system, economy of influence, conflicting dependence and political clientelism.

Elimination of net neutrality

Net neutrality is also at stake when media mergers occur. Net neutrality involves a lack of restrictions on content on the internet, however, with big businesses supporting campaigns financially they tend to have influence over political issues, which can translate into their mediums. These big businesses that also have control over internet usage or the airwaves could possibly make the content available biased from their political stand point or they could restrict usage for conflicting political views, therefore eliminating net neutrality.

Issues

Concentration of media ownership is very frequently seen as a problem of contemporary media and society.

Freedom of the press and editorial independence

Johannes von Dohnanyi, in a 2003 report published by the Organization for Security and Co-operation in Europe (OSCE)'s Office of the Representative on Freedom of the Media, argued market concentration among media—whether driven by domestic or foreign investors—should be "closely monitored" because "Horizontal concentration may cause dangers to media pluralism and diversity, while vertical concentration may result in entry barriers for new competitors." Von Dohnanyi argues that to "safeguard free and independent print media and protect professional journalism as one of the cornerstones of constitutional democracy" there should be standards for editorial independence, better labor protections for professional journalists, and independent institutions "to monitor the implementation and observance of all laws and regulations regarding concentration processes, media pluralism, content diversity and journalistic freedoms."

Deregulation

Robert W. McChesney argues that the concentration of media ownership is caused by a shift to neoliberal deregulation policies, which is a market-driven approach. Deregulation effectively removes governmental barriers to allow for the commercial exploitation of media. Motivation for media firms to merge includes increased profit-margins, reduced risk and maintaining a competitive edge. In contrast to this, those who support deregulation have argued that cultural trade barriers and regulations harm consumers and domestic support in the form of subsidies hinders countries to develop their own strong media firms. The opening of borders is more beneficial to countries than maintaining protectionist regulations.

Critics of media deregulation and the resulting concentration of ownership fear that such trends will only continue to reduce the diversity of information provided, as well as to reduce the accountability of information providers to the public. The ultimate consequence of consolidation, critics argue, is a poorly informed public, restricted to a reduced array of media options that offer only information that does not harm the media oligopoly's growing range of interests.

For those critics, media deregulation is a dangerous trend, facilitating an increase in concentration of media ownership, and subsequently reducing the overall quality and diversity of information communicated through major media channels. Increased concentration of media ownership can lead to corporate censorship affecting a wide range of critical thought.

Media pluralism

The concentration of media ownership is commonly regarded as one of the crucial aspects reducing media pluralism. A high concentration of the media market increases the chances to reduce the plurality of political, cultural and social points of views. Even if ownership of the media is one of the main concerns when it comes to assessing media pluralism, the concept of media pluralism is broader as it touches many aspects, from merger control rules to editorial freedom, the status of public service broadcasters, the working conditions of journalists, the relationship between media and politics, representation of local and regional communities and the inclusion of minorities' voices. Also, it embraces all measures guaranteeing citizens' access to diversified sources so to allow the formation of a plurality of opinions in the public sphere without undue influence of dominant powers.

Furthermore, media pluralism has a two-fold dimension, or rather internal and external. Internal pluralism concerns pluralism within a specific media organisation: in this regard, many countries request public broadcast services to account for a variety of views and opinions, including those of minority groups. External pluralism applies instead to the overall media landscape, for instance in terms of the number of media outlets operating in a given country.

Media ownership can pose serious challenges to pluralism when owners interfere with journalists' independence and editorial line. However, in a free market economy, owners must have the capacity to decide the strategy of their company to remain competitive in the market. Also, pluralism does not mean neutrality and lack of opinion, as having an editorial line is an integral part of the role of editors provided that this line is transparent and explicit to both the staff and audience.

Determinants of media pluralism

Size and wealth of the market

"Within any free market economy, the level of resources available for the provision of media will be constrained principally by the size and wealth of that economy, and the propensity of its inhabitants to consume media." [Gillian Doyle; 2002:15] Those countries that have a relatively large market, like the United Kingdom, France or Spain have more financial background to support diversity of output and have the ability to keep more media companies in the market (as they are there to make profit). More diverse output and fragmented ownership will, obviously, support pluralism. In contrast, small markets like Ireland or Hungary suffer from the absence of the diversity of output given in countries with bigger markets. It means that "support for the media through direct payment" and "levels of consumers expenditure", furthermore "the availability of advertising support" [Gillian Doyle; 2002:15] are less in these countries, due to the low number of audience. Overall, the size and wealth of the market determine the diversity of both media output and media ownership.

Consolidation of resources

The consolidation of cost functions and cost-sharing. Cost-sharing is a common practice in monomedia and cross media. For example, "for multi-product television or radio broadcasters, the more homogeneity possible between different services held in common ownership (or the more elements within a programme schedule which can be shared between 'different' stations), the greater the opportunity to reap economies". Though the main concern of pluralism is that different organization under different ownership may buy the same e.g. news stories from the same news-supplier agency. In the UK, the biggest news-supplier is The Press Association (PA). Here is a quoted text from PA web site: "The Press Association supplies services to every national and regional daily newspaper, major broadcasters, online publishers and a wide range of commercial organisations." Overall, in a system where all different media organizations gather their stories from the same source, we can't really call that system pluralist. That is where diversity of output comes in.

Pluralism in media ownership

Media privatization and the lessening of state dominance over media content has continued since 2012. In the Arab region, the Arab States Broadcasting Union (ASBU) counted 1,230 television stations broadcasting via Arab and international satellites, of which 133 were state-owned and 1,097 private. According to the ASBU Report, these numbers serve as evidence of a decline in the percentage of state channels and a rise in national private and foreign public stations targeting the Arab region. The reduction of direct government ownership over the whole media sector is commonly registered as a positive trend, but this has paralleled by a growth in outlets with a sectarian agenda.

In Africa, some private media outlets have maintained close ties to governments or individual politicians, while media houses owned by politically non-aligned individuals have struggled to survive, often in the face of advertising boycotts by state agencies. In almost all regions, models of public service broadcasting have been struggling for funding. In Western, Central and Eastern Europe, funds directed to public service broadcasting have been stagnating or declining since 2012.

New types of cross-ownership have emerged in the past five years that have spurred new questions about where to draw the line between media and other industries. A notable case has been the acquisition of The Washington Post by the founder of online retailer Amazon. While the move initially raised concerns about the newspaper's independence, the newspaper has significantly increased its standing in the online media—and print—and introduced significant innovations.

The community-centred media ownership model continues to survive in some areas, especially in isolated, rural or disadvantaged areas, and mostly pertaining to radio. Through this model, not-for-profit media outlets are run and managed by the communities they serve.

In particular nations

Australia

Further information: Media ownership in Australia

Controls over media ownership in Australia are laid down in the Broadcasting Services Act 1992, administered by the Australian Communications and Media Authority (ACMA). Even with laws in place Australia has a high concentration of media ownership. Ownership of national and the newspapers of each capital city are dominated by two corporations, Rupert Murdoch's News Corp Australia, (which was founded in Adelaide as News Limited) and Nine Entertainment Co. These two corporations along with Seven West Media co-own Australian Associated Press which distributes the news and then sells it on to other outlets such as the Australian Broadcasting Corporation. Although much of the everyday mainstream news is drawn from the Australian Associated Press, all the privately owned media outlets still compete with each other for exclusive pop culture news. Rural and regional media is dominated by Australian Community Media, with significant holdings in all states and territories. Daily Mail and General Trust operate the DMG Radio Australia commercial radio networks in metropolitan and regional areas of Australia. Formed in 1996, it has since become one of the largest radio media companies in the country. The company currently own more than 60 radio stations across New South Wales, Victoria, South Australia, Queensland and Western Australia.

There are rules governing foreign ownership of Australian media and these rules were loosened by the former Howard Government.

Media Watch is an independent media watchdog televised on the public broadcaster Australian Broadcasting Corporation (ABC), which is one of two government-administered channels, the other being Special Broadcasting Service (SBS).

In late 2011, the Finkelstein Inquiry into media regulation was launched, and reported its findings back to the federal government in early 2012.

New Zealand

Independent Newspapers Limited (INL) formerly published the Wellington-based newspapers The Dominion and The Evening Post, in addition to purchasing a large shareholding in pay TV broadcaster Sky Media Limited in 1997. These two newspapers merged to form the Dominion Post in 2002, and in 2003, sold its entire print media division to Fairfax New Zealand. The remainder of the company officially merged with Sky Media Limited in 2005 to form Sky Network Television Limited.

When INL ceased publishing the Auckland Star in 1991, The New Zealand Herald became the Auckland region's sole daily newspaper. The New Zealand Herald and the New Zealand Listener, formerly privately held by the Wilson & Horton families, was sold to APN News & Media in 1996. The long-running news syndication agency NZPA announced that it would close down in 2011, with operations to be taken over by 3 separate agencies, APN's APNZ, Fairfax's FNZN and AAP's NZN, all owned by Australian parent companies. In 2014, APN's New Zealand division officially changed its name to NZME, in order to reflect the company's convergence with its radio division The Radio Network. As of early 2015, Fairfax New Zealand and NZME have a near duopoly on newspapers and magazines in New Zealand. In May 2016, NZME and Fairfax NZ announced merger talks, pending Commerce Commission approval.

Commercial radio stations are largely divided up between MediaWorks New Zealand and NZME, with MediaWorks also owning TV3 and C4 (now The Edge TV). Television New Zealand, although 100% state-owned, has been run on an almost entirely commercial basis since the late 1980s, in spite of previous attempts to steer it towards a more public service-oriented role. Its primary public-service outlet, TVNZ7, ceased broadcasting in 2012 due to non-renewal of funding, and the youth-oriented TVNZ6 was rebranded as the short-lived commercial channel TVNZ U. In addition, the TVNZ channels Kidzone (and formerly TVNZ Heartland) are only available through Sky Network Television and not on the Freeview platform.

Sky Network Television has had an effective monopoly on pay TV in New Zealand since its nearest rival Saturn Communications (later part of TelstraClear and now Vodafone New Zealand) began wholesaling Sky content in 2002. However, in 2011, TelstraClear CEO Allan Freeth warned it would review its wholesale agreement with Sky unless it allowed TelstraClear to purchase non-Sky content.

Canada

Main article: Media ownership in Canada

Canada has the biggest concentrated TV ownership out of all the G8 countries and it comes in second place for the most concentrated television viewers.

Broadcasting and telecommunications in Canada are regulated by the Canadian Radio-television and Telecommunications Commission (CRTC), an independent governing agency that aims to serve the needs and interests of citizens, industries, interest groups and the government. The CRTC does not regulate newspapers or magazines.

Apart from a relatively small number of community broadcasters, media in Canada are primarily owned by a small number of groups, including Bell Canada, the Shaw family (via Corus Entertainment and Shaw Communications), Rogers Communications, Quebecor, and the government-owned CBC/Radio-Canada. Each of these companies holds a diverse mix of television, specialty television, and radio operations. Bell, Rogers, Shaw, and Quebecor also engage in the telecommunications industry with their ownership of internet providers, television providers, and mobile carriers, while Rogers is also involved in publishing.

In 2007, CTVglobemedia, Rogers Media and Quebecor all expanded significantly through the acquisitions of CHUM Limited, CityTV and Osprey Media, respectively. In 2010, Canwest Global Communications, having filed for bankruptcy, sold its television assets to Shaw (through a new subsidiary, Shaw Media) and spun off its newspaper holdings into Postmedia Network, a new company founded by the National Post's CEO Paul Godfrey. Later that year, Bell also announced that it would acquire the remaining shares of CTVglobemedia (which was originally majority owned by Bell when it was formed in 2001; Bell had reduced its stake in the following years), forming Bell Media.

Between 1990 and 2005 there were a number of media corporate mergers and takeovers in Canada. For example, in 1990, 17.3% of daily newspapers were independently owned; whereas in 2005, 1% were. These changes, among others, caused the Senate Standing Committee on Transport and Communications to launch a study of Canadian news media in March 2003. (This topic had been examined twice in the past, by the Davey Commission (1970) and the Kent Commission (1981), both of which produced recommendations that were never implemented in any meaningful way.)

The Senate Committee's final report, released in June 2006, expressed concern about the effects of the current levels of news media ownership in Canada. Specifically, the committee discussed their concerns regarding the following trends: the potential of media ownership concentration to limit news diversity and reduce news quality; the CRTC and Competition Bureau's ineffectiveness at stopping media ownership concentration; the lack of federal funding for the CBC and the broadcaster's uncertain mandate and role; diminishing employment standards for journalists (including less job security, less journalistic freedom, and new contractual threats to intellectual property); a lack of Canadian training and research institutes; and difficulties with the federal government's support for print media and the absence of funding for the internet-based news media.

The Senate report expressed particular concern about the concentration of ownership in the province of New Brunswick, where the Irving business empire owns all the English-language daily newspapers and most of the weeklies. Senator Joan Fraser, author of the report, stated, "We didn't find anywhere else in the developed world a situation like the situation in New Brunswick."

The report provided 40 recommendations and 10 suggestions (for areas outside of federal government jurisdiction), including legislation amendments that would trigger automatic reviews of a proposed media merger if certain thresholds are reached, and CRTC regulation revisions to ensure that access to the broadcasting system is encouraged and that a diversity of news and information programming is available through these services.

Public inquires into the concentration of ownership and its impact upon democracy. The Canadian regulatory framework imposes requirements upon the protection and enhancement of Canadian culture (through regulation, subsidies and the operation of the CBC). Increasing acceptance of media/news as commercial enterprise in 1990s driven by: hegemony of new-liberalism, role of commodified information technology in economic growth, commitment to private sector "champions" of Canadian culture.

Brazil

For broader coverage of this topic, see Brazil § Media.

In Brazil, the concentration of media ownership seems to have manifested itself very early. Dr. Venício A. de Lima noted in 2003:

in Brazil there is an environment very conducive to concentration. Sectorial legislation has been timid, by express intention of the legislator, by failing to include direct provisions that limit or control the concentration of ownership, which, incidentally, goes in the opposite direction of what happens in countries like France, Italy and the United Kingdom, which are concerned with the plurality and diversity in the new scenario of technological convergence.

— Lobato, Folha de S.Paulo, 10/14/2001

Lima points to other factors that would make media concentration easier, particularly in broadcasting: the failure of legal norms that limit the equity interest of the same economic group in various broadcasting organizations; a short period (five years) for resell broadcasting concessions, facilitating the concentration by the big media groups through the purchase of independent stations, and no restrictions to the formation of national broadcasting networks. He cites examples of horizontal, vertical, crossed and "in cross" concentration (a Brazilian peculiarity).

• Horizontal concentration: oligopoly or monopoly produced within an area or industry; television (pay or free) is the Brazilian classical model. In 2002 the cable networks Sky and NET dominated 61% of the Brazilian market. In the same year, 58.37% of all advertising budgets were invested in TV – and in this aspect, TV Globo and its affiliates received 78% of the amount.
• Vertical concentration: integration of the different phases of production and distribution, eliminating the work of independent producers. In Brazil, unlike the United States, it is common for a TV network to produce, advertise, market and distribute most of its programming. TV Globo is known for its soap operas exported to dozens of countries; it keeps under permanent contract the actors, authors, and the whole production staff. The final product is broadcast by a network of newspapers, magazines, radio stations and websites owned by Globo Organizations.
• Cross ownership: ownership of different kinds of media (TV, newspapers, magazines, etc.) by the same group. Initially, the phenomenon occurred in radio, television and print media, with emphasis on the group of "Diários Associados." At a later stage appeared the RBS Group (affiliated to TV Globo), with operations in the markets of Rio Grande do Sul and Santa Catarina. Besides being the owner of radio and television stations, and of the main local newspapers, it has two Internet portals. The opinions of its commentators are thus replicated by a multimedia system that makes it extremely easy to spread the point of view advocated by the group.
• Monopoly "in cross": reproduction into local level, of the particularities of cross ownership. Research carried out in the early 1990s, detected the presence of this singularity in 18 of the 26 Brazilian states. Manifests itself by the presence of a TV channel with a large audience, often linked to TV Globo and by the existence of two daily newspapers, in which the one with the largest circulation is linked to the major television channel and to a network of radio stations, that almost always reproduces articles and the editorial line of the newspaper "O Globo". In 2002, another survey (which did not include pay TV), found the presence of the "monopoly in cross" in 13 major markets in Brazil.

The UNESCO office in Brasília has expressed its concern over the existence of an outdated code of telecommunications (1962), which no longer meets the expectations generated by the Brazilian Constitution of 1988 in the political and social fields, and the inability of the Brazilian government to establish an independent regulatory agency to manage the media. Attempts in this direction have been pointed by the mainstream media as attacks on freedom of expression, the trend of the political left in the entire Latin American continent.

Europe

Council of Europe and European Union

Since the 1980, a significant debate has developed at the European level concerning the regulation of media ownership and the principles to be adopted to regulate media ownership concentration. Both the Council of Europe (CoE) and the European Union (EU) have tried to formulate a distinctive and comprehensive media policy, including on the issue of concentration. However, the emphasis of both the organisations was more on strengthening media diversity and pluralism than on limiting concentration, even though they have often expressed the need for common European media concentration regulations. However, the European Union enforces a common regulation for environmental protection, consumer protection and human rights, but it has none for media pluralism.

Although there is no specific media concentration legislation at the European level, a number of existing legal instruments such as the Amsterdam Protocol, the Audiovisual Media Services Directive and actions programs contribute directly and indirectly to curbing media concentration at EU level.

When it comes to regulating media concentration at the common European level, there is a conflict between Member states and the European Commission (EC). Even if Member states do not publicly challenge the need for common regulation on media concentration, they push to incorporate their own regulatory approach at the EU level and are reluctant to give the European Union their regulatory power on the issue of media concentration.

The Council of Europe's initiative promoting media pluralism and curbing media concentration dates back to the mid-1970s. Several resolutions, recommendations, declarations by the Council of Europe Committee of Ministers and studies by experts' groups have addressed the issue since then. The council's approach has been mainly addressed at defining and protecting media pluralism, defined in terms of pluralism of media content in order to allow a plurality of ideas and opinions.

Within the European Union, two main standpoints have emerged in the debate: on the one hand, the European Parliament has favoured the idea that, considering the crucial role that media play in the functioning of democratic systems, policies in this field should prevent excessive concentration in order to guarantee pluralism and diversity. On the other hand, the European Commission has privileged the understanding that the media sector should be regulated, as any other economic field, following the principles of market harmonization and liberalization.

Indeed, media concentration issues can be addressed both by general competition policies and by specific media sector rules. According to some scholars, given the vital importance of contemporary media, sector-specific competition rules in the media industries should be enhanced. Within the EU, the Council regulation 4064/89/EEC on the control of concentrations between undertakings as part of European competition legislation covered also media concentration cases. The need for sector-specific regulation has been widely supported by both media scholars and the European Parliament. In the 1980s, when preparing legislation on cross-border television many experts and MEPs argued for including provisions for media concentration in the EU directive but these efforts failed. In 1992, the Commission of the European Communities published a policy document named "Pluralism and Media Concentration in the internal Market – an assessment of the need for Community action" which outlined three options on the issue of media concentration regulation at the Community level, i.e. no specific action to be taken; action regulating transparency; and action to harmonize laws. Out of these options, the first one was chosen but the debate on this decision lasted for years. Council regulation as a tool for regulating media concentration was excluded and the two proposals on a media concentration directive advanced in the mid 1990s were not backed by the commission. As a consequence, efforts at legislating media concentration at Community level were phased out by the end of the 1990s.

Despite a wide consensus over the idea that the vital importance of contemporary media justifies to regulate media concentration through sector-specific concentration rules going beyond the general competition policy, the need for sector specific regulation has been challenged in recent years due to the peculiar evolution of the media industry in the digital environment and media convergence. In practice, sector-specific media concentration rules have been abolished in some European countries in recent years.

As a consequence, scholars Harcourt and Picard argue that "the trend has been to remove ownership rules and restrictions on media ownership within Europe in order that 'domestic champions' can bulk up to 'fend off' the US threat. This has been a key argument for the loosening of ownership rules within Europe."

In 2002, the European Parliament tried to revitalize the efforts on regulating media concentration at the European level and adopted a resolution on media concentration which called on the European Commission to launch a broad and comprehensive consultation on media pluralism and media concentration and to prepare a Green Paper on the issue by the end of 2003. The European Commission failed to meet this deadline. In the following years, during the process of amending the Televisions Without Frontiers directive, which was adopted by the EP and the Council in 2007, the issue of media concentration was discussed, but it did not represent the core of the debate. In 2003, the European Commission issued a policy document named "The future of European Regulatory Audiovisual Policy" which stressed that, in order to ensure media pluralism, measures should aim at limiting the level of media concentration by establishing "maximum holdings in media companies and prevent[ing] cumulative control or participation in several media companies at the same time".

In 2007, reacting to concerns on media concentration and its repercussion on pluralism and freedom of expression in the EU member states raised by the European Parliament and by NGOs, the European Commission launched a new three-phase plan on media pluralism.

In October 2009, a European Union Directive was proposed to set for all member states common and higher standards for media pluralism and freedom of expression. The proposal was put to a vote in the European Parliament and rejected by just three votes. The directive was supported by the liberal-centrists, the progressives and the greens, and was opposed by the European People's Party. Unexpectedly, the Irish liberals made an exception by voting against the directive, and later revealed that they had been pressured by the Irish right-wing government to do so.

Following this debate, the European Commission commissioned a large, in depth study published in 2009 aiming to identify the indicators to be adopted to assess media pluralism in Europe.

The "Independent Study on Indicators for Media Pluralism in the Member States – Towards a Risk-Based Approach" provided a prototype of indicators and country reports for 27 EU member states. After years of refining and preliminary testings, the study resulted in the Media Pluralism Monitor (MPM), a yearly monitoring carried out by the Centre for Media Pluralism and Freedom at the European University Institute in Florence on a variety of aspects affecting media pluralism, including also the concentration of media ownership is considered. To assess the risk that media ownership concentration in a given country may actually hinder media pluralism, the MPM takes into account three specific elements:

• Horizontal concentration, that is concentration of media ownership within a given media sector (press, audio-visual, etc.);
• Cross-media concentration across different media markets;
• Transparency of media ownership.

In 2015, the MPM was carried out in 19 European countries. The results of the monitoring activity in the field of media market concentration identify five countries as facing a high risk: Finland, Luxembourg, Lithuania, Poland and Spain. There are nine countries facing a medium risk: Czech Republic, Germany, Ireland, Latvia, Netherlands, Portugal, Romania, Sweden. Finally, only five countries face a low risk: Croatia, Cyprus, Malta, Slovenia and Slovakia. In the monitoring carried out in 2014, 7 of 9 countries (Belgium, Bulgaria, Denmark, France, Hungary, Italy, the UK) scored a high risk in audience concentration.

Pan-European groups

A 2016 report based on data collected by MAVISE, a free online database on audiovisual services and companies in Europe, highlights the growing number of Pan-European media companies in the field of broadcasting and divides them into different categories: multi‐country media groups, controlling "channels that play an important role in various national markets (for example Modern Times Group, CEME, RTL, a Luxembourg-based media group operating in 10 countries, and Sanoma). These groups generally control a high market share in the countries in which they operate, and have gradually emerged through the acquisition of existing channels or by establishing new companies in countries in which they were not already present. The four groups RTL Group, CEME, Modern Times Group and Sanoma are major players (in the top 4 regarding audience share) in 19 European countries (RTL Group, CEME and Modern Times Group are major players in 17 countries). Pan‐European broadcasters operate with a unique identity and well recognized brands across Europe. Most of them are based in the United States and have progressively expanded their activities in the European market. In many cases, these groups evolved from being content creators to also deliver such contents through channels renamed after the original brands.

Examples of such pan-European groups include Warner Bros. Discovery, Paramount Global, and The Walt Disney Company, pan‐European distribution groups (cable and satellite operators), companies that operate at the European level in the distribution sector via cable, satellite or IPTV. The emergence of major actors operating in this field has been made possible mainly thanks to the process of digitalization and benefit of specific economies of scale.

EU Member States

Czech Republic

In the Czech Republic about 80% of the newspapers and magazines were owned by German and Swiss corporations in 2007, as the two main press groups Vltava Labe Media and Mafra were (completely or partly) controlled by the German group Rheinisch-Bergische Druckerei- und Verlagsgesellschaft (Mediengruppe Rheinische Post), but were both later purchased by Czech-owned conglomerates Penta Investments and Agrofert in 2015 and 2013 respectively. Several major media previously owned by Swiss company Ringier became Czech-owned through their acquisition by the Czech News Center in 2013.

• Vltava Labe Media, a subsidiary of Penta Investments, that owns the tabloids ŠÍP and ŠÍP EXTRA, 73 regional dailies Deník and other 26 weeklies and that is major shareholder of publishing houses Astrosat and Melinor and 100% owner of Metropol and also partly controls the distribution of all the prints through PNS, a.s. which was previously part of the German Verlagsgruppe Passau [de] (that controls also the German Neue Presse Verlags, the Polish Polskapresse and the Slovak Petit Press).
• Mafra, a subsidiary of Agrofert (that owns the centre-right dailies Dnes, Lidové noviny, the local edition of the freesheet Metro, the periodical 14dní, several monthly magazines, the TV music channel Óčko, the radio stations Expresradio and Rádio Classic FM, several web portals and partly controls, together with Vltava-Labe-Press, the distribution company PNS, a.s.) was previously owned by the German Rheinisch-Bergische Drückerei- und Verlagsgesellschaft, prior to its acquisition by Agrofert.
• Czech News Center controls 16 Czech daily tabloids and weeklies (such as 24 hodin, Abc, Aha!, Blesk, Blesk TV Magazin, Blesk pro ženy, Blesk Hobby, Blesk Zdravi, Nedělní Blesk, Nedělní Sport, Reflex, Sport, Sport Magazin) as well as 7 web portals, reaching approximately 3.2 million readers.

Czech governments have defended foreign newspaper ownership as a manifestation of the principle of the free movement of capital.

The weekly Respekt is published by R-Presse, the majority of whose shares are owned by former Czech Minister of Foreign Affairs Karel Schwarzenberg. The national television market is dominated by four terrestrial stations, two public (Czech TV1 and Czech TV2) and two private (NOVA TV and Prima TV), which draw 95% of audience share. Concerning the diversity of output, this is limited by a series of factors: the average low level of professional education among Czech journalists is compensated by "informal professionalization", leading to a degree of conformity in approaches; political parties hold strong ties in Czech media, especially print, where more than 50% of Czech journalists identify with the Right, while only 16% express sympathy for the Left; and the process of commercialization and "tabloidization" has increased, lowering differentiation of content in Czech print media.

Germany

Axel Springer AG is one of the largest newspaper publishing companies in Europe, claiming to have over 150 newspapers and magazines in over 30 countries in Europe. In the 1960s and 1970s the company's media followed an aggressive conservative policy (see Springerpresse). It publishes Germany's only nationwide tabloid, Bild, and one of Germany's most important broadsheets, Die Welt. Axel Springer also owns a number of regional newspapers, especially in Saxony and in the Hamburg Metropolitan Region, giving the company a de facto monopoly in the latter case. An attempt to buy one of Germany's two major private TV Groups, ProSiebenSat.1, in 2006, was withdrawn due to large concerns by regulation authorities as well as by parts of the public. The company is also active in Hungary, where it is the biggest publisher of regional newspapers, and in Poland, where it owns the best-selling tabloid Fakt, one of the nation's most important broadsheets, Dziennik, and is one of the biggest shareholder in the second-ranked private TV company, Polsat.

Bertelsmann is one of the world's largest media companies. It owns RTL Group, which is one of the two major private TV companies in both Germany and the Netherlands and also owning assets in Belgium, France, UK, Spain, Czech and Hungary. Bertelsmann also owns Gruner + Jahr, Germany's biggest popular magazine publisher, including popular news magazine Stern and a 26% share in investigative news magazine Der Spiegel. Bertelsmann also owns Random House, a book publisher, ranked first in the English-speaking world and second in Germany.

Ireland

In Ireland, the company Independent News & Media owns many national newspapers: the Evening Herald, Irish Independent, Sunday Independent, Sunday World and Irish Daily Star. It also owns 29.9% of the Sunday Tribune. Broadcast media is divided between state owned RTÉ, which operates several radio stations and television channels and started digital radio and television services in the early 2010s, TG4, an Irish language broadcaster, and TV3, a commercial television operator. Denis O'Brien an Irish billionaire with a fortune partly accumulated through the Esat Digifone licence controversy, formed Communicorp Group Ltd in 1989, with the company currently owning 42 radio stations in 8 European countries, including Ireland's Newstalk, Today FM, Dublin's 98FM, SPIN 1038 and SPIN South West. In January 2006, O'Brien took a stake in Tony O'Reilly's Independent News & Media (IN&M). As of May 2012, he holds a 29.9% stake in the company, making him the largest shareholder; the O'Reilly family's stake is around 13%.

Italy

Further information: Silvio Berlusconi § Media control and conflict of interest

Silvio Berlusconi, the former Prime Minister of Italy, is the major shareholder of – by far – Italy's biggest (and de facto only) private free TV company, Mediaset; Italy's biggest publisher, Mondadori; and Italy's biggest advertising company, Publitalia [it]. One of Italy's nationwide dailies, Il Giornale, is owned by his brother, Paolo Berlusconi, and another, Il Foglio, by his former wife, Veronica Lario. Berlusconi has often been criticized for using the media assets he owns to advance his political career.

United Kingdom

In Britain and Ireland, Rupert Murdoch owns best-selling tabloid The Sun as well as the broadsheet The Times and Sunday Times, in addition having also owned 39% of satellite broadcasting network BSkyB. In March 2011, the United Kingdom provisionally approved Murdoch to buy the remaining 61% of BSkyB; however, subsequent events (News of the World hacking scandal and its closure in July 2011) leading to the Leveson Inquiry have halted this takeover. In 2019, despite the British government granting formal permission for a new take over of Sky (conditional on the divestiture of Sky News), Fox were outbid by American conglomerate Comcast.

Reach own five major national titles, the Daily Mirror, Sunday Mirror and The Sunday People, and the Scottish Sunday Mail and Daily Record as well as over 100 regional newspapers. They claim to have a monthly digital reach of 73 million people.

Daily Mail and General Trust (DMGT) own the Daily Mail and The Mail on Sunday, Ireland on Sunday, and free London daily Metro, and control a large proportion of regional media, including through subsidiary Northcliffe Media, in addition to large shares in ITN and GCap Media.

The Guardian is owned by Guardian Media Group.

Richard Desmond owns OK! magazine, the Daily Express, and the Daily Star. He used to own Channel 5; on 1 May 2014 the channel was acquired by Viacom for £450 million (US$759 million).

The Evening Standard and former print publication The Independent are both partly owned by British-Russian media boss Evgeny Lebedev.

BBC News produces news for its television channels and radio stations.

Independent Television News produces news for ITV, Channel 4 and Channel 5.

Independent Radio News, which has a contract with Sky News, produces news for the most popular commercial radio stations.

India

See also: Media of India

In India a few political parties also own media organizations, for example the proprietors of Kalaignar TV are close aides of Tamil Nadu's former Chief Minister M. Karunanidhi. So is also the case with Sun TV. SRM university owner Pachamuthu, a member of Parliament, has stakes in Pudhiyathalaimurai News Channel. AMMK General Secretary TTV Dinakaran, MLA's close aides run Jaya TV. Sakshi TV a Telugu channel in Andhra Pradesh is owned by ex-chief minister's son and family.

Israel

In Israel, Arnon Mozes owns the most widespread Hebrew newspaper, Yediot Aharonot, the most widespread Russian newspaper Vesty, the most popular Hebrew news website Ynet, and 17% of the cable TV firm HOT. Moreover, Mozes owns the Reshet TV firm, which is one of the two operators of the most popular channel in Israel, Channel 2.

Mexico

In Mexico there are only two national broadcast television service companies, Televisa and Azteca. These two broadcasters together administer 434 of the 461 total commercial television stations in the country (94.14%).

Though concern about the existence of a duopoly had been around for some time, a press uproar sparked in 2006, when a controversial reform to the Federal Radio and Television Law, seriously hampered the entry of new competitors, like Cadena Tres.

Televisa also owns subscription TV enterprises Cablevision (Mexico) [es] and SKY, a publishing company Editorial Televisa [es], and the Televisa Radio broadcast radio network, creating a de facto media monopoly in many regions of the country.

United States

Main article: Media cross-ownership in the United States

Recent media mergers in the United States

An infographic created by Jason at Frugal Dad states that in 1983, 90% of US media was controlled by 50 companies, and that in 2011, 90% was controlled by just 6 companies. One of the companies listed, News Corporation, was split into two separate companies on June 28, 2013, with publishing assets and Australian media assets going to News Corp and broadcasting and media assets going to 21st Century Fox.

Film industry

In the United States, movie production has been dominated by major studios since the early 20th century; before that, there was a period in which Edison's Trust monopolized the industry. The music and television industries recently witnessed cases of media consolidation, with Sony Music Entertainment's parent company merging their music division with Bertelsmann AG's BMG to form Sony BMG and Tribune's The WB and CBS Corp.'s UPN merging to form The CW. In the case of Sony BMG, there existed a "Big Five" (now "Big Four") of major record companies, while The CW's creation was an attempt to consolidate ratings and stand up to the "Big Four" of American network (terrestrial) television (this despite the fact that the CW was, in fact, partially owned by one of the Big Four in CBS). In television, the vast majority of broadcast and basic cable networks, over a hundred in all, are controlled by seven corporations: Fox Corporation, The Walt Disney Company (which includes the ABC, ESPN, FX and Disney brands), National Amusements (which owns Paramount Global), Comcast (which owns NBCUniversal), Warner Bros. Discovery, E. W. Scripps Company, Cablevision (now known as Altice USA), or some combination thereof.

There may also be some large-scale owners in an industry that are not the causes of monopoly or oligopoly. iHeartMedia (formerly Clear Channel Communications), especially since the Telecommunications Act of 1996, acquired many radio stations across the United States, and came to own more than 1,200 stations. However, the radio broadcasting industry in the United States and elsewhere can be regarded as oligopolistic regardless of the existence of such a player. Because radio stations are local in reach, each licensing a specific part of spectrum from the FCC in a specific local area, any local market is served by a limited number of stations. In most countries, this system of licensing makes many markets local oligopolies. The similar market structure exists for television broadcasting, cable systems and newspaper industries, all of which are characterized by the existence of large-scale owners. Concentration of ownership is often found in these industries.

Effect of ownership on coverage

In a 2020 article, Herzog and Scerbinina argued that CNN's coverage in 2017 of a potential merger between its parent company Time Warner and AT&T was "self-centered, self-promoting, and self-legitimizing."

Venezuela

About 70% of Venezuelan TV and radio stations are privately owned, while only about 5% or less of these stations are currently state-owned. The remaining stations are mostly community owned. VTV was the only state TV channel in Venezuela only about a decade ago. For the last decade, through the present day, the Venezuelan government operates and owns five more stations.

Commercial outlets completely rule over the radio sector. However, the Venezuelan government funds a good number of radio shows and TV stations. The primary newspapers of Venezuela are private companies that are frequently condemning of their government. These newspapers being produced in Venezuela do not have a large following.