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Topic Review
Prehistoric Paintings in Magura Cave
The paintings are made of bat guano applied over limestone, therefore two sets of laboratory specimens were considered: stone specimens and stone specimens covered with a layer of sterilized bat guano. The two investigated treatments were a commercial product based on ethyl silicate (“ES”) and a solution of diammonium hydrogen phosphate (“DAP”), aimed at forming calcium phosphates. The results of the study indicate that both treatments were able to increase mechanical properties of stone, the increase being higher for “DAP”. Both consolidants caused acceptable color changes, but the “ES” treatment significantly decreased stone wettability, water absorption and water vapor permeability, while the “DAP” treatment slightly affected those properties. In the stone+guano specimens, the presence of the guano layer affected the penetration of the consolidants, thus partly reducing their effectiveness. Compared to the stone samples, the guano layer experienced a more intense color change, alongside visible cracking. However, the adopted methodology to replicate the cave paintings was not completely successful, as the so-deposited guano layer was very prone to detachment when dry, unlike cave paintings. Future work will be dedicated to assess the consolidant performance onto samples that resemble even more closely the conditions of the cave paintings, by improving the methodology for the guano layer deposition and by contaminating specimens with soluble salts before consolidant application.
  • 8.6K
  • 02 Nov 2020
Topic Review
History of Democratic Socialism
Democratic socialism represents the modernist development of socialism and its outspoken support for democracy. The origins of democratic socialism can be traced back to 19th-century utopian socialist thinkers and the Chartist movement in Great 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. 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 the 19th century, the ruling classes were afraid of socialism because it challenged their rule. Socialism has faced opposition since then, and the opposition to it has often been organized and violent. In countries such as Germany and Italy, democratic socialist parties were banned, like with Otto von Bismarck's Anti-Socialist Laws. With the expansion of liberal democracy and universal suffrage during the 20th century, democratic socialism became a mainstream movement which expanded across the world, as centre-left and left-wing parties came to govern, became the main opposition party, or simply a commonality of the democratic process in most of the Western world; one major exception was the United States. Democratic socialist parties greatly contributed to existing liberal democracy.
  • 8.6K
  • 22 Nov 2022
Topic Review
Mercedes-Benz W108
The Mercedes-Benz W108 and W109 are luxury cars produced by Mercedes-Benz from 1965 through to 1972 and 1973 in North America only. The line was an update of the predecessor W111 and W112 fintail sedans. The cars were successful in West Germany and in export markets including North America and Southeast Asia. During the seven-year run, a total of 383,361 units were manufactured.
  • 8.6K
  • 19 Oct 2022
Topic Review
SoundCloud
SoundCloud is an online audio distribution platform and music sharing website based in Berlin, Germany that enables its users to upload, promote, and share audio.
  • 8.6K
  • 20 Oct 2022
Topic Review
Incineration Bottom Ash from Municipal Solid Waste
Incineration bottom ash (IBA) is the main residue from municipal solid waste (MSW) incineration and refers to the incombustible materials that remain in the furnace after combustion. IBA is a very heterogeneous material, comprising irregularly shaped particles and a wide particle size distribution. This material is a complex inorganic mixture generally composed of melt products, minerals, metallic compounds, ceramics, and glass [1]. The classification and the management practices of IBA differ worldwide and, particularly, among the EU Member States. However, different applications have been studied for this material.
  • 8.6K
  • 24 Dec 2021
Topic Review
Expectation–Disconfirmation Theory and Brand
Combining brand equity indicators with Expectation–Disconfirmation Theory (EDT) provides insight into the hardly measurable influential variables of brand loyalty and brand equity evaluation. The results suggest that the satisfaction level (i.e., product evaluation) can be explained in more depth by the divided response shift indicator in the case of a familiar, low involvement product such as mineral water. It can be stated that the positive and negative disconfirmations of the response shift, which measures the weight of a brand in the overall evaluation of a product, can provide accurate information for brand managers.
  • 8.6K
  • 26 Jul 2022
Topic Review
Cluster Chemistry
In chemistry, a cluster is an ensemble of bound atoms or molecules that is intermediate in size between a molecule and a bulk solid. Clusters exist of diverse stoichiometries and nuclearities. For example, carbon and boron atoms form fullerene and borane clusters, respectively. Transition metals and main group elements form especially robust clusters. Clusters can also consist solely of a certain kind of molecules, such as water clusters. The phrase cluster was coined by F.A. Cotton in the early 1960s to refer to compounds containing metal–metal bonds. In another definition a cluster compound contains a group of two or more metal atoms where direct and substantial metal bonding is present. The prefixed terms "nuclear" and "metallic" are used and imply different meanings. For example, polynuclear refers to a cluster with more than one metal atom, regardless of the elemental identities. Heteronuclear refers to a cluster with at least two different metal elements. The main cluster types are "naked" clusters (without stabilizing ligands) and those with ligands. For transition metal clusters, typical stabilizing ligands include carbon monoxide, halides, isocyanides, alkenes, and hydrides. For main group elements, typical clusters are stabilized by hydride ligands. Transition metal clusters are frequently composed of refractory metal atoms. In general metal centers with extended d-orbitals form stable clusters because of favorable overlap of valence orbitals. Thus, metals with a low oxidation state for the later metals and mid-oxidation states for the early metals tend to form stable clusters. Polynuclear metal carbonyls are generally found in late transition metals with low formal oxidation states. The polyhedral skeletal electron pair theory or Wade's electron counting rules predict trends in the stability and structures of many metal clusters. Jemmis mno rules have provided additional insight into the relative stability of metal clusters.
  • 8.6K
  • 08 Nov 2022
Topic Review
Essential Oil Prevents COVID-19
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV‑2), also known as coronavirus disease-2019 (COVID-19), is a pandemic disease that has been declared as modern history’s gravest health emergency worldwide. Until now, no precise treatment modality has been developed. The angiotensin-converting enzyme 2 (ACE2) receptor, a host cell receptor, has been found to play a crucial role in virus cell entry; therefore, ACE2 blockers can be a potential target for anti-viral intervention. In this study, we evaluated the ACE2 inhibitory effects of 10 essential oils. Among them, geranium and lemon oils displayed significant ACE2 inhibitory effects in epithelial cells. In addition, immunoblotting and qPCR analysis also confirmed that geranium and lemon oils possess potent ACE2 inhibitory effects. Furthermore, the gas chromatography-mass spectrometry (GC–MS) analysis displayed 22 compounds in geranium oil and 9 compounds in lemon oil. Citronellol, geraniol, and neryl acetate were the major compounds of geranium oil and limonene that represented major compound of lemon oil. Next, we found that treatment with citronellol and limonene significantly downregulated ACE2 expression in epithelial cells. The results suggest that geranium and lemon essential oils and their derivative compounds are valuable natural anti-viral agents that may contribute to the prevention of the invasion of SARS-CoV-2/COVID-19 into the human body.
  • 8.6K
  • 13 Feb 2021
Topic Review
Lisbon Treaty
The Lisbon Treaty has brought significant changes to the institutional structure of the European Union. The traditional three pillar system has been abolished and provisions regarding formal Union institutions have been amended. The aim of this encyclopedia entry is to briefly describe the functioning of each of the formal EU institutions after the Lisbon amendment. More specifically, their main tasks and powers will be shortly presented, whilst more extensive bibliography will be provided. In this regard, the reader will be in position to understand the fundamentals of the EU institutional structure and also find valuable sources for further research.
  • 8.6K
  • 16 Mar 2021
Topic Review
Problems Associated with Plant Micropropagation
The production of micropropagated plants in plant-tissue-culture laboratories and nurseries is the most important method for propagation of many economic plants. Micropropagation based on tissue-culture technology involves large-scale propagation, as it allows multiplication of a huge number of true-to-type propagules in a very short time and in a very limited space, as well as all year round, regardless of the climate.
  • 8.6K
  • 04 Aug 2022
Topic Review
Edge Couplers
Silicon photonics has drawn increasing attention since recent decades and is promising to act as a key technology for future daily applications due to its various merits including ultra-low cost, high integration density owing to the high refractive index of silicon and compatibility with current semiconductor fabrication process. Optical interconnects is an important issue in silicon photonic integrated circuits to transmit light and fiber-to-chip optical interconnects is vital in application scenarios like data centers and optical transmission systems. There are mainly two categories of fiber-to-chip optical coupling, that is off-plane coupling and in-plane coupling. Grating couplers work under the former category while edge couplers function as in-plane coupling. In this paper, we mainly focus on edge couplers in silicon photonic integrated circuits. We deliver an introduction to the research background, operation mechanism and design principles of silicon photonic edge couplers. The state-of-the-art of edge couplers is reviewed according to different configurations as to the device structure, identifying the performance, fabrication feasibility and applications. In addition, a brief comparison between edge couplers and grating couplers is conducted. Packaging issue is also discussed and several prospective techniques for further improvements of edge couplers are proposed.
  • 8.6K
  • 27 Oct 2020
Topic Review
Phenomenology
Phenomenology (from Greek φαινόμενον, phainómenon "that which appears" and λόγος, lógos "study") is the philosophical study of the structures of experience and consciousness. As a philosophical movement it was founded in the early years of the 20th century by Edmund Husserl and was later expanded upon by a circle of his followers at the universities of Göttingen and Munich in Germany . It then spread to France , the United States , and elsewhere, often in contexts far removed from Husserl's early work. Phenomenology is not a unified movement; rather, the works of different authors share a 'family resemblance' but with many significant differences. Gabriella Farina states:Phenomenology, in Husserl's conception, is primarily concerned with the systematic reflection on and study of the structures of consciousness and the phenomena that appear in acts of consciousness. Phenomenology can be clearly differentiated from the Cartesian method of analysis which sees the world as objects, sets of objects, and objects acting and reacting upon one another. Husserl's conception of phenomenology has been criticized and developed not only by him but also by students and colleagues such as Edith Stein, Max Scheler, Roman Ingarden, and Dietrich von Hildebrand, by existentialists such as Nicolai Hartmann, Gabriel Marcel, Maurice Merleau-Ponty, and Jean-Paul Sartre, by hermeneutic philosophers such as Martin Heidegger, Hans-Georg Gadamer, and Paul Ricoeur, by later French philosophers such as Jean-Luc Marion, Michel Henry, Emmanuel Levinas, and Jacques Derrida, by sociologists such as Alfred Schütz and Eric Voegelin, and by Christian philosophers, such as Dallas Willard.
  • 8.6K
  • 28 Nov 2022
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
  • 8.6K
  • 27 Jul 2021
Topic Review
Grievance Studies Affair
The Grievance Studies affair, also referred to as "hoax" or the "Sokal Squared" scandal (in reference to a similar 1996 hoax), was an attempt by a team of three authors (James A. Lindsay, Peter Boghossian, and Helen Pluckrose) to create bogus academic papers and submit them to academic journals with the intent of testing the strength of the editorial and peer review process. The hoax began in 2017 and ended in 2018. The authors targeted the academic areas of cultural, race, gender, fat, and sexuality studies in which they believed poor science was undermining the field, which they collectively refer to as "grievance studies". The project was halted early after one of the papers was criticized on social media, then its authenticity questioned on Campus Reform, and finally the hoax being more broadly exposed by the Wall Street Journal in 2018 alongside a YouTube video created and released by documentary filmmaker Mike Nayna. By the time of the reveal, four of their 20 papers had been published, one had won an award, three had been accepted but not yet published, six had been rejected, and seven were still under review.
  • 8.6K
  • 08 Nov 2022
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.
  • 8.6K
  • 22 Nov 2022
Topic Review
Bloch Wave
A Bloch wave (also called Bloch state or Bloch function or Bloch wavefunction), named after Swiss physicist Felix Bloch, is a kind of wave function which can be written as a plane wave modulated by a periodic function. By definition, if a wave is a Bloch wave, its wavefunction can be written in the form: where [math]\displaystyle{ \mathbf{r} }[/math] is position, [math]\displaystyle{ \psi }[/math] is the Bloch wave, [math]\displaystyle{ u }[/math] is a periodic function with the same periodicity as the crystal, the wave vector [math]\displaystyle{ \mathbf{k} }[/math] is the crystal momentum vector, [math]\displaystyle{ \mathrm{e} }[/math] is Euler's number, and [math]\displaystyle{ \mathrm{i} }[/math] is the imaginary unit. Bloch waves are important in solid-state physics, where they are often used to describe an electron in a crystal. This application is motivated by Bloch's theorem, which states that the energy eigenstates for an electron in a crystal can be written as Bloch waves (more precisely, it states that the electron wave functions in a crystal have a basis consisting entirely of Bloch wave energy eigenstates). This fact underlies the concept of electronic band structures. These Bloch wave energy eigenstates are written with subscripts as [math]\displaystyle{ \psi_{n\mathbf{k}} }[/math], where [math]\displaystyle{ n }[/math] is a discrete index, called the band index, which is present because there are many different Bloch waves with the same [math]\displaystyle{ \mathbf{k} }[/math] (each has a different periodic component [math]\displaystyle{ u }[/math]). Within a band (i.e., for fixed [math]\displaystyle{ n }[/math]), [math]\displaystyle{ \psi_{n\mathbf{k}} }[/math] varies continuously with [math]\displaystyle{ \mathbf{k} }[/math], as does its energy. Also, for any reciprocal lattice vector [math]\displaystyle{ \mathbf{K} }[/math], [math]\displaystyle{ \psi_{n\mathbf{k}}=\psi_{n(\mathbf{k+K})} }[/math]. Therefore, all distinct Bloch waves occur for values of [math]\displaystyle{ \mathbf{k} }[/math] which fall within the first Brillouin zone of the reciprocal lattice.
  • 8.6K
  • 30 Nov 2022
Topic Review
Left-Wing Market Anarchism
Left-wing market anarchism is a strand of free-market anarchism and an individualist anarchist, left-libertarian and libertarian socialist political philosophy and market socialist economic theory stressing the value of radically free markets, termed freed markets to distinguish them from the common conception which these libertarians believe to be riddled with statist and capitalist privileges. Proponents of this approach distinguish themselves from right-libertarians and strongly affirm the classical liberal ideas of self-ownership and free markets while maintaining that taken to their logical conclusions these ideas support anti-capitalist, anti-corporatist, anti-hierarchical and pro-labor positions in economics; anti-imperialism in foreign policy; and thoroughly radical views regarding socio-cultural issues. Key theorists in this area include contemporary scholars such as Kevin Carson, Gary Chartier, Charles W. Johnson, Roderick T. Long, Chris Matthew Sciabarra, Ryan Neugebauer, Sheldon Richman and Brad Spangler. The genealogy of left-wing market anarchism, sometimes labeled market-oriented or free-market left-libertarianism, overlaps to a significant degree with that of Steiner–Vallentyne left-libertarianism as the roots of that tradition are sketched in the book The Origins of Left-Libertarianism. Carson–Long-style left-libertarianism is rooted in 19th-century mutualism and in the work of figures such as Thomas Hodgskin, French Liberal School thinkers such as Gustave de Molinari and American individualist anarchists such as Benjamin Tucker and Lysander Spooner, among others. Several left-wing market anarchists who come from the left-Rothbardian school or tradition cite Murray Rothbard's homestead principle with approval to support worker cooperatives. While with notable exceptions libertarians in the United States after the heyday of individualist anarchism tended to ally with the political right, relationships between such libertarians and the New Left thrived in the 1960s, laying the groundwork for modern left-wing market anarchism. Left-wing market anarchism identifies with left-libertarianism, a position which names several related yet distinct approaches to politics, society, culture and political and social theory, stressing both individual freedom and social justice. Unlike right-libertarians, left-libertarians believe that neither claiming nor mixing one's labor with natural resources is enough to generate full private property rights and maintain that all natural resources such as land, oil and gold ought to be held in some egalitarian manner, either unowned or owned collectively. Those left-libertarians who support private property do so under different property norms and theories, or under the condition that recompense is offered to the local or global community.
  • 8.6K
  • 30 Nov 2022
Topic Review
Transparency for Architecture
Rowe and Slutzky proposed two types of transparency in architecture in the essay, “Transparency: Literal and Phenomenal”. They divided transparency into literal, meaning the material conditions of glass, and phenomenal, as derived from Cubist paintings. “literal transparency” describes the material quality of being see-through, and phenomenal transparency describes the perceptual attributes that allow the mind to discern the underlying governing concepts or spatial concepts. Through their idea of “phenomenal transparency”, they primarily investigated the relationship of visual perceptions using the human eye with superimposed two-dimensional visions of architectural space and the world.
  • 8.5K
  • 27 Aug 2021
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".
  • 8.5K
  • 05 Dec 2022
Topic Review
International Trade Theory
International trade theory is a sub-field of economics which analyzes the patterns of international trade, its origins, and its welfare implications. International trade policy has been highly controversial since the 18th century. International trade theory and economics itself have developed as means to evaluate the effects of trade policies.
  • 8.5K
  • 14 Nov 2022
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