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Topic Review
Fresh Fruit Supply Chain Optimization
The fresh fruit chain has been recognized as a very important and strategic part of the economic development of many countries. The planning framework for production and distribution is highly complex as a result. Mathematical models have been developed over the decades to deal with this complexity. This review focuses on the recent progress in mathematically based decision making to account for uncertainties in the fresh fruit supply chain
  • 5.4K
  • 27 Jul 2021
Topic Review
Limit Point
In mathematics, a limit point (or cluster point or accumulation point) of a set [math]\displaystyle{ S }[/math] in a topological space [math]\displaystyle{ X }[/math] is a point [math]\displaystyle{ x }[/math] that can be "approximated" by points of [math]\displaystyle{ S }[/math] in the sense that every neighbourhood of [math]\displaystyle{ x }[/math] with respect to the topology on [math]\displaystyle{ X }[/math] also contains a point of [math]\displaystyle{ S }[/math] other than [math]\displaystyle{ x }[/math] itself. A limit point of a set [math]\displaystyle{ S }[/math] does not itself have to be an element of [math]\displaystyle{ S. }[/math] There is also a closely related concept for sequences. A cluster point or accumulation point of a sequence [math]\displaystyle{ (x_n)_{n \in \mathbb{N}} }[/math] in a topological space [math]\displaystyle{ X }[/math] is a point [math]\displaystyle{ x }[/math] such that, for every neighbourhood [math]\displaystyle{ V }[/math] of [math]\displaystyle{ x, }[/math] there are infinitely many natural numbers [math]\displaystyle{ n }[/math] such that [math]\displaystyle{ x_n \in V. }[/math] This definition of a cluster or accumulation point of a sequence generalizes to nets and filters. In contrast to sets, for a sequence, net, or filter, the term "limit point" is not synonymous with a "cluster/accumulation point"; by definition, the similarly named notion of a limit point of a filter (respectively, a limit point of a sequence, a limit point of a net) refers to a point that the filter converges to (respectively, the sequence converges to, the net converges to). The limit points of a set should not be confused with adherent points for which every neighbourhood of [math]\displaystyle{ x }[/math] contains a point of [math]\displaystyle{ S }[/math]. Unlike for limit points, this point of [math]\displaystyle{ S }[/math] may be [math]\displaystyle{ x }[/math] itself. A limit point can be characterized as an adherent point that is not an isolated point. Limit points of a set should also not be confused with boundary points. For example, [math]\displaystyle{ 0 }[/math] is a boundary point (but not a limit point) of set [math]\displaystyle{ \{ 0 \} }[/math] in [math]\displaystyle{ \R }[/math] with standard topology. However, [math]\displaystyle{ 0.5 }[/math] is a limit point (though not a boundary point) of interval [math]\displaystyle{ [0, 1] }[/math] in [math]\displaystyle{ \R }[/math] with standard topology (for a less trivial example of a limit point, see the first caption). This concept profitably generalizes the notion of a limit and is the underpinning of concepts such as closed set and topological closure. Indeed, a set is closed if and only if it contains all of its limit points, and the topological closure operation can be thought of as an operation that enriches a set by uniting it with its limit points.
  • 5.4K
  • 25 Oct 2022
Topic Review
Democratic Socialism
Democratic socialism is a political philosophy that supports political democracy and some form of a socially owned economy,({{{1}}}, {{{2}}}) with a particular emphasis on economic democracy, workplace democracy, and workers' self-management within a market socialist economy, or an alternative form of decentralised planned socialist economy. Democratic socialists argue that capitalism is inherently incompatible with the values of freedom, equality, and solidarity and that these ideals can only be achieved through the realisation of a socialist society. Although most democratic socialists seek a gradual transition to socialism,({{{1}}}, {{{2}}}) democratic socialism can support either revolutionary or reformist politics as means to establish socialism.({{{1}}}, {{{2}}}) Democratic socialism was popularized by socialists who were opposed to the backsliding towards a one-party state in the Soviet Union and other nations during the 20th century.({{{1}}}, {{{2}}}) The history of democratic socialism can be traced back to 19th-century socialist thinkers across Europe and the Chartist movement in Britain, which somewhat differed in their goals but shared a common demand of democratic decision making and public ownership of the means of production, and viewed these as fundamental characteristics of the society they advocated for. In the late 19th to the early 20th century, democratic socialism was also heavily influenced by the gradualist form of socialism promoted by the British Fabian Society and Eduard Bernstein's evolutionary socialism in Germany.({{{1}}}, {{{2}}}) Democratic socialism is what most socialists understand by the concept of socialism;({{{1}}}, {{{2}}}) it may be a very broad (socialists who reject a one-party Marxist–Leninist state)({{{1}}}, {{{2}}}) or more limited concept (post-war social democracy).({{{1}}}, {{{2}}}) As a broad movement, it includes forms of libertarian socialism,({{{1}}}, {{{2}}}) market socialism,({{{1}}}, {{{2}}}) reformist socialism, and revolutionary socialism,({{{1}}}, {{{2}}}) as well as ethical socialism,({{{1}}}, {{{2}}}) liberal socialism,({{{1}}}, {{{2}}}) social democracy,({{{1}}}, {{{2}}}) and some forms of state socialism and utopian socialism, all of which share commitment to democracy.({{{1}}}, {{{2}}}) Democratic socialism is contrasted with Marxism–Leninism, which opponents often perceive as being authoritarian and undemocratic in practice.({{{1}}}, {{{2}}}) Democratic socialists oppose the Stalinist political system and the Soviet-type economic planning system, rejecting as their form of governance the administrative-command system that formed in the Soviet Union and other Marxist–Leninist states during the 20th century. Democratic socialism is also distinguished from Third Way social democracy[nb 1] on the basis that democratic socialists are committed to systemic transformation of the economy from capitalism to socialism.[nb 2] While having socialism as a long-term goal,({{{1}}}, {{{2}}}) some moderate democratic socialists are more concerned about curbing capitalism's excesses, and are supportive of progressive reforms to humanise it in the present day,({{{1}}}, {{{2}}}) while other democratic socialists believe that economic interventionism and similar policy reforms aimed at addressing social inequalities and suppressing the economic contradictions of capitalism would only exacerbate the contradictions,({{{1}}}, {{{2}}}) causing them to emerge elsewhere under a different guise.({{{1}}}, {{{2}}}) Those democratic socialists believe that the fundamental issues with capitalism are systemic in nature, and can only be resolved by replacing the capitalist mode of production with the socialist mode of production through the replacement of private ownership with collective ownership of the means of production, and extending democracy to the economic sphere in the form of industrial democracy.({{{1}}}, {{{2}}}) The main criticism of democratic socialism is focused on the compatibility of democracy and socialism. Several academics and political commentators tend to distinguish between authoritarian socialism and democratic socialism as a political ideology, with the first representing the Soviet Bloc, and the latter representing the democratic socialist parties in the Western Bloc countries that have been democratically elected in countries such as Britain, France, and Sweden, among others.({{{1}}}, {{{2}}}) However, following the end of the Cold War, many of these countries have moved away from socialism as a neoliberal consensus replaced the social democratic consensus in the advanced capitalist world.
  • 5.4K
  • 17 Oct 2022
Topic Review
Photocatalysts
Photocatalysts indicates the acceleration of a chemical reaction occurring on the surface of a semiconductor material (the catalyst) caused by the presence of light. Illumination of the catalyst causes the generation of free changes (electrons and holes) that can partecipate to chemical reactions, thus causing (or acceleratin) them. Photocatalysis con be used in hydrogen (H2) production (e.g., via water splitting or photo-reforming of organic substrates), CO2 reduction, pollution mitigation and water or air remediation via oxidation (photodegradation) of pollutants. Titanium dioxide (TiO2) is a “benchmark” photocatalyst, thanks to many favorable characteristics.
  • 5.4K
  • 26 May 2021
Topic Review
Crowd Sensing
Crowd sensing (also known as participatory sensing, or mobile crowdsensing) is a means of collecting people’s surrounding information via mobile sensing devices. Its highly expressive and powerful sensing capabilities can carry out a big sensing project by fragmenting tasks into small pieces. The key to success is to get more participants to collect higher quality data. 
  • 5.4K
  • 28 Oct 2020
Topic Review
Normal Strain
In physics, deformation is the continuum mechanics transformation of a body from a reference configuration to a current configuration. A configuration is a set containing the positions of all particles of the body. A deformation can occur because of external loads, intrinsic activity (e.g. muscle contraction), body forces (such as gravity or electromagnetic forces), or changes in temperature, moisture content, or chemical reactions, etc. Strain is related to deformation in terms of relative displacement of particles in the body that excludes rigid-body motions. Different equivalent choices may be made for the expression of a strain field depending on whether it is defined with respect to the initial or the final configuration of the body and on whether the metric tensor or its dual is considered. In a continuous body, a deformation field results from a stress field due to applied forces or because of some changes in the temperature field of the body. The relation between stress and strain is expressed by constitutive equations, e.g., Hooke's law for linear elastic materials. Deformations which cease to exist after the stress field is removed are termed as elastic deformation. In this case, the continuum completely recovers its original configuration. On the other hand, irreversible deformations remain. They exist even after stresses have been removed. One type of irreversible deformation is plastic deformation, which occurs in material bodies after stresses have attained a certain threshold value known as the elastic limit or yield stress, and are the result of slip, or dislocation mechanisms at the atomic level. Another type of irreversible deformation is viscous deformation, which is the irreversible part of viscoelastic deformation. In the case of elastic deformations, the response function linking strain to the deforming stress is the compliance tensor of the material.
  • 5.4K
  • 21 Oct 2022
Topic Review
Literacy
Literacy is traditionally defined as the ability to read and write. In the modern world, this is one way of interpreting literacy. A more broad interpretation is literacy as knowledge and competence in a specific area. The concept of literacy has evolved in meaning. The modern term's meaning has been expanded to include the ability to use language, numbers, images, computers, and other basic means to understand, communicate, gain useful knowledge, solve mathematical problems and use the dominant symbol systems of a culture. The concept of literacy is expanding across OECD countries to include skills to access knowledge through technology and ability to assess complex contexts. A person who travels and resides in a foreign country but is unable to read or write in the language of the host country would also be regarded by the locals as illiterate. The key to literacy is reading development, a progression of skills that begins with the ability to understand spoken words and decode written words, and culminates in the deep understanding of text. Reading development involves a range of complex language underpinnings including awareness of speech sounds (phonology), spelling patterns (orthography), word meaning (semantics), grammar (syntax) and patterns of word formation (morphology), all of which provide a necessary platform for reading fluency and comprehension. Once these skills are acquired, the reader can attain full language literacy, which includes the abilities to apply to printed material critical analysis, inference and synthesis; to write with accuracy and coherence; and to use information and insights from text as the basis for informed decisions and creative thought. The inability to do so is called illiteracy or analphabetism. The United Nations Educational, Scientific and Cultural Organization (UNESCO) defines literacy as the "ability to identify, understand, interpret, create, communicate and compute, using printed and written materials associated with varying contexts. Literacy involves a continuum of learning in enabling individuals to achieve their goals, to develop their knowledge and potential, and to participate fully in their community and wider society".
  • 5.4K
  • 05 Dec 2022
Topic Review
Accretion (Astrophysics)
In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, in an accretion disk. Most astronomical objects, such as galaxies, stars, and planets, are formed by accretion processes.
  • 5.4K
  • 11 Nov 2022
Topic Review
Hydrogen for Cooking
About 3 billion people use conventional carbon-based fuels such as wood, charcoal, and animal dung for their daily cooking needs. Cooking with biomass causes deforestation and habitat loss, emissions of greenhouse gases, and smoke pollution that affects people’s health and well-being. Hydrogen can play a role in enabling clean and safe cooking by reducing household air pollution and reducing greenhouse gas emissions.
  • 5.4K
  • 12 Jan 2023
Topic Review
Ropiness in Bread - A Re-Emerging Spoilage Phenomenon
As bread is a very important staple food, its spoilage threatens global food security. Ropy bread spoilage manifests in sticky and stringy degradation of the crumb, slime formation, discoloration, and an odor reminiscent of rotting fruit. Increasing consumer demand for preservative-free products and global warming may increase the occurrence of ropy spoilage. Bacillus amyloliquefaciens, B. subtilis, B. licheniformis, the B. cereus group, B. pumilus, B. sonorensis, Cytobacillus firmus, Niallia circulans, Paenibacillus polymyxa, and Priestia megaterium were reported to cause ropiness in bread. To date, the underlying mechanisms behind ropy bread spoilage remain unclear, high-throughput screening tools to identify rope-forming bacteria are missing, and only a limited number of strategies to reduce rope spoilage were described.
  • 5.4K
  • 26 Oct 2022
Topic Review
Pollen Germination in Gymnosperms
Gymnosperms are amazing representatives of the flora. On the one hand, they are ancient plants with primitive characteristics of anatomical structure; on the other hand, they are perfectly adapted to their habitat and are the dominant species in many ecosystems due to their impressive size and longevity, with their reproductive system being of particular interest. It has progressive features, because in this group the reduced male gametophyte—pollen grain—first appeared, as well as the ability to form seeds. In addition, this group still represents a wide variety of reproductive patterns, strategies, and relationships. For example, the degree of gametophyte reduction varies, there are both zooidogamy and siphonogamy, and the reproductive process can both be relatively fast and last over several years.
  • 5.4K
  • 20 Jul 2021
Topic Review
Water-Gas Shift Reaction
The water-gas shift reaction (WGSR) describes the reaction of carbon monoxide and water vapor to form carbon dioxide and hydrogen: The water gas shift reaction was discovered by Italian physicist Felice Fontana in 1780. It was not until much later that the industrial value of this reaction was realized. Before the early 20th century, hydrogen was obtained by reacting steam under high pressure with iron to produce iron, iron oxide and hydrogen. With the development of industrial processes that required hydrogen, such as the Haber–Bosch ammonia synthesis, a less expensive and more efficient method of hydrogen production was needed. As a resolution to this problem, the WGSR was combined with the gasification of coal to produce a pure hydrogen product. As the idea of hydrogen economy gains popularity, the focus on hydrogen as a replacement fuel source for hydrocarbons is increasing.
  • 5.4K
  • 22 Nov 2022
Topic Review
Xenobiotic Pollution and Its Impact on the Environment
In the industrial revolution and urbanization era, the global environment’s poisoning by a complex mixture of xenobiotics has become a major environmental threat worldwide. Xenobiotic contaminants such as azodyes, phenolics, polycyclic aromatic hydrocarbons (PAHs), halogenated compounds, personal care products (PCPs), pharmaceuticals’ active compounds (PhACs), pesticides, nitroaromatic compounds, triazines, and chlorinated compounds adversely affect the environment by their long-term persistence and slow or no biodegradation in the ecosystems. Xenobiotic pollution of the environment is a global concern caused by anthropogenic activities such as urbanization and population expansion. The enormous amounts of harmful compounds released into the environment result in widespread ecosystem contamination. Prominent substances such as polycyclic aromatic hydrocarbons, heavy metal ions, pesticides, fertilizers, and oil derivatives are found in soil, sediment, and water. 
  • 5.4K
  • 07 Sep 2022
Topic Review
Support Needs in Intellectual Disability
“Support needs” is a psychological construct referring to the pattern and intensity of supports necessary for a person to participate in activities linked with normative human functioning.
  • 5.4K
  • 11 Jan 2021
Topic Review
Public Transport in Shanghai
Shanghai has an extensive public transport system, largely based on buses, trolley buses, taxis, and a rapidly expanding metro system. Shanghai has invested heavily in public transportation before and after the 2010 World Expo, including the construction of the Hongqiao transportation hub of high-speed rail, air, metro and bus routes. Public transport is the major mode of transport in Shanghai as limitations on car purchases were introduced in 1994 in order to limit the growth of automobile traffic and alleviate congestion. New private cars cannot be driven without a license plate, which are sold in monthly license plate auctions which is only accessible for locally registered residents and those who have paid social insurance or individual income taxes for over three years. Around 9,500 license plates are auctioned each month, and the average price is about CN¥89,600 (US$12,739) in 2019. Shanghai (population of 25 million) has over four million cars on the road, the fifth-largest number of any Chinese city. Despite this the city remains plagued by congestion and vehicle pollution. The results of the "2011 Shanghai Public Transport Passenger Flow Survey" released by the Municipal Transportation and Port Bureau showed that the city's public transport travel time was gradually reduced. The average travel distance of public transport in 2011 was 8.5 kilometers, the travel time 50.8 minutes per trip and the travel cost of public transport is gradually reduced: in 2011, the cost of rail transit was 2.4 yuan per trip, down 14% from 2005; the cost of bus and tram trips was 1.8 yuan, down 5% from 2005. Metro accounted for 33% of the public transport passenger volume. In 2018 the public transportation system handled a total of 16.05 million rides on average each day, among which 10.17 million (63%) were made via the Metro and 5.76 million (36%) via buses. Shanghai expressway traffic volume was 1.215 million vehicles on an average day.
  • 5.3K
  • 08 Nov 2022
Topic Review
Dorsal Root Injury
Dorsal root injury results in regional loss of sensorimotor function, and often severe neuropathic pain. Studying pathophysiological mechanisms of dorsal root injury and the development of novel treatments for this condition may contribute to therapeutic progress also for direct injuries to the spinal cord.
  • 5.3K
  • 13 Oct 2021
Topic Review
Cholera Outbreaks and Pandemics
Seven cholera pandemics have occurred in the past 200 years, with the first pandemic originating in India in 1817. Additionally, there have been many documented cholera outbreaks, such as a 1991–1994 outbreak in South America and, more recently, the 2016–2021 Yemen cholera outbreak. Although much is known about the mechanisms behind the spread of cholera, this has not led to a full understanding of what makes cholera outbreaks happen in some places and not others. Lack of treatment of human feces and lack of treatment of drinking water greatly facilitate its spread. Bodies of water have been found to serve as a reservoir, and seafood shipped long distances can spread the disease. Between 1816 and 1923, the first six cholera pandemics occurred consecutively and continuously over time. Increased commerce, migration, and pilgrimage are credited for its transmission. Late in this period (particularly 1879–1883), major scientific breakthroughs toward the treatment of cholera develop: the first immunization by Pasteur, the development of the first cholera vaccine, and identification of the bacterium Vibrio cholerae by Filippo Pacini and Robert Koch. After a long hiatus, a seventh cholera pandemic spread in 1961. The pandemic subsided in the 1970s, but continued on a smaller scale. Outbreaks occur across the developing world to the current day. Epidemics occurred after wars, civil unrest, or natural disasters, when water and food supplies had become contaminated with Vibrio cholerae, and also due to crowded living conditions and poor sanitation. Deaths in India between 1817 and 1860 in the first three pandemics of the nineteenth century, are estimated to have exceeded 15 million people. Another 23 million died between 1865 and 1917, during the next three pandemics. Cholera deaths in the Russian Empire during a similar time period exceeded 2 million.
  • 5.3K
  • 20 Oct 2022
Topic Review
Turbocharged Direct Injection
Turbocharged direct injection or TDI is a design of turbodiesel engines featuring turbocharging and cylinder-direct fuel injection that was developed and produced by the Volkswagen Group (VW AG). These TDI engines are widely used in all mainstream Volkswagen Group marques of passenger cars and light commercial vehicles made by the company (particularly those sold in Europe). They are also used as marine engines in Volkswagen Marine and Volkswagen Industrial Motor applications. TDI engines installed in 2009 to 2015 model year Volkswagen Group cars sold through 18 September 2015 had an emissions defeat device, which activated emissions controls only during emissions testing. The emissions controls were suppressed otherwise, allowing the TDI engines to exceed legal limits on emissions. VW has admitted to using the illegal device in its TDI diesel cars. In many countries, TDI is a registered trademark of Volkswagen AG. The TDI designation has also been used on vehicles powered by Land Rover-designed diesel engines. These are unrelated to Volkswagen Group engines.
  • 5.3K
  • 08 Nov 2022
Topic Review
Social Construction of Disability
The social construction of disability comes from a paradigm of ideas that suggest that society's beliefs about a particular community, group or population are grounded in the power structures inherent in a society at any given time. These are often steeped in historical representations of the issue and social expectations surrounding concepts such as disability, thereby enabling a social construct around what society deems disabled and healthy. Ideas surrounding disability stem from societal attitudes, often connected to who is deserving or undeserving, and deemed productive to society at any given time. For example, in the medieval period, a person's moral behavior established disability. Disability was a divine punishment or side effect of a moral failing; being physically or biologically different was not enough to be considered disabled. Only during the European Enlightenment did society change its definition of disability to be more related to biology. However, what most Western Europeans considered to be healthy determined the new biological definition of health.
  • 5.3K
  • 11 Nov 2022
Topic Review
Copper(II) Complex
A dinuclear copper(II) complex of (1) (where bipy = 2,2′‑bipyridine, bzt = benzoate and ox = oxalate) was synthesised and characterised by diffractometric (powder and single-crystal XRD) and thermogravimetric (TG/DTG) analyses, spectroscopic techniques (IR, Raman, electron paramagnetic resonance spectroscopy (EPR) and electronic spectroscopy), magnetic measurements and density functional theory (DFT) calculations. The analysis of the crystal structure revealed that the oxalate ligand is in bis(bidentate) coordination mode between two copper(II) centres. The other four positions of the coordination environment of the copper(II) ion are occupied by one water molecule, a bidentate bipy and a monodentate bzt ligand. An inversion centre located on the ox ligand generates the other half of the dinuclear complex. Intermolecular hydrogen bonds and pi-pi for the organisation of the molecules in the solid state. Molar magnetic susceptibility and field dependence magnetisation studies evidenced a weak intramolecular–ferromagnetic interaction (J = +2.9 cm‑1) between the metal ions. The sign and magnitude of the calculated J value by density functional theory (DFT) are in agreement with the experimental data.
  • 5.3K
  • 30 Oct 2020
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