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Topic Review

Sustainability Strategies in the Automotive Industry

The automotive industry is a complex system of connections, direct and indirect products, and interactions for the purpose of creating economic value. As this industry has a significant impact on the environment, the economy, and people, it also plays a significant role in sustainable development. Regulatory agencies evaluate car and parts companies to ensure that these companies meet environmental standards and reduce the environmental impact of production processes and products themselves.

3.9K
19 Apr 2022

Topic Review

Atomic Mass Unit

The dalton or unified atomic mass unit (SI symbols: Da or u) is a unit of mass widely used in physics and chemistry. . It is approximately the mass of one nucleon (either a proton or neutron). A mass of 1 Da is also referred to as the atomic mass constant and denoted by mu. Several definitions of this unit have been used, implying slightly different values. The current IUPAC endorsed definition is the unified atomic mass unit, denoted by the symbol u. As of 2019, the International System of Units (SI) lists the dalton, symbol Da, as a unit acceptable for use with the SI unit system and secondarily notes that the dalton (Da) and the unified atomic mass unit (u) are alternative names (and symbols) for the same unit. The symbol Da is more widely used in most fields. It is defined precisely as 1/12 of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. Despite being an official abbreviation for a related obsolete unit and not widely used in the scientific literature, the abbreviation "amu" now often refers to the modern unit (Da or u) in many preparatory texts. As of June 2019, the value recommended by the Committee on Data for Science and Technology (CODATA) is 1.66053906660(50)×10−27 kg, or approximately 1.66 yoctograms. This unit is commonly used in physics and chemistry to express the mass of atomic-scale objects, such as atoms, molecules, and elementary particles. For example, an atom of helium has a mass of about 4 Da, and a molecule of acetylsalicylic acid (aspirin), C9H8O4, has a mass of about 180.16 Da. In general, the standard atomic weight of an element is the average weight of its atom as it occurs in nature, expressed in daltons. The molecular masses of proteins, nucleic acids, and other large polymers are often expressed with the units kilodalton (kDa), equal to 1000 daltons, megadalton (MDa), one million daltons, etc. Titin, one of the largest known proteins, has an atomic mass of between 3 and 3.7 megadaltons. The DNA of chromosome 1 in the human genome has about 249 million base pairs, each with an average mass of about 650 Da, or 156 GDa total. The mole is a unit of amount of substance, widely used in chemistry and physics, which was originally defined so that the mass of one mole of a substance, measured in grams, would be numerically equal to the average mass of one of its constituent particles, measured in daltons. That is, the molar mass of a chemical compound was meant to be numerically equal to its average molecular mass. For example, the average mass of one molecule of water is about 18.0153 daltons, and one mole of water is about 18.0153 grams. A protein whose molecule has an average mass of 64 kDa would have a molar mass of 64 kg/mol. However, while this equality can be assumed for almost all practical purposes, it is now only approximate, because of the way the mole was redefined on 20 May 2019. The mass in daltons of an atom is numerically very close to the number of nucleons A in its atomic nucleus. It follows that the molar mass of a compound (grams per mole) is also numerically close to the average number of nucleons per molecule. However, the mass of an atomic-scale object is affected by the binding energy of the nucleons in its atomic nuclei, as well as the mass and binding energy of the electrons. Therefore, this equality holds only for the carbon-12 atom in the stated conditions, and will vary for other substances. For example, the mass of one unbound atom of the common hydrogen isotope (hydrogen-1, protium) is 1.007825032241(94) Da, the mass of one free neutron is 1.008664915823(491) Da, and the mass of one hydrogen-2 (deuterium) atom is 2.014101778114(122) Da. In general, the difference (mass defect) is less than 0.1%; except for hydrogen (about 0.8%), helium-3 (0.5%), lithium (0.25%) and beryllium (0.15%). The atomic mass unit should not be confused with unit of mass in the atomic units systems, which is instead the electron rest mass (me).

3.9K
31 Oct 2022

Topic Review

In mathematics, particularly in functional analysis and topology, closed graph is a property of functions. A function f : X → Y between topological spaces has a closed graph if its graph is a closed subset of the product space X × Y. A related property is open graph. This property is studied because there are many theorems, known as closed graph theorems, giving conditions under which a function with a closed graph is necessarily continuous. One particularly well-known class of closed graph theorems are the closed graph theorems in functional analysis.

3.9K
18 Oct 2022

Topic Review

In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different types combine to form an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue and smooth muscle tissue. Two or more organs working together in the execution of a specific body function form an organ system, also called a biological system or body system. An organ's tissues can be broadly categorized as parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland's tissue that makes the hormones is the parenchyma, whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the connective tissues that provide a suitable place for it to be situated and anchored. The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. Organs exist in most multicellular organisms. In single-celled organisms such as bacteria, the functional analogue of an organ is known as an organelle. In plants, there are three main organs. In the study of anatomy, viscera (singular viscus) refers to the internal organs of the abdominal, thoracic, and pelvic cavities. The abdominal organs may be classified as solid organs, or hollow organs. The solid organs are the liver, pancreas, spleen, kidneys, and adrenal glands. The hollow organs of the abdomen are the stomach, intestines, gallbladder, bladder, and rectum. In the thoracic cavity the heart is a hollow, muscular organ. The number of organs in any organism depends on the definition used. By one widely adopted definition, 79 organs have been identified in the human body.

3.9K
14 Oct 2022

Topic Review

WikiLeaks (/ˈwɪkiliːks/) is an international non-profit organisation that publishes news leaks and classified media provided by anonymous sources. Its website, initiated in 2006 in Iceland by the organisation Sunshine Press, stated in 2015 that it had released online 10 million documents in its first 10 years. Julian Assange, an Australian Internet activist, is generally described as its founder and director. Since September 2018, Kristinn Hrafnsson has served as its editor-in-chief. WikiLeaks has variously described itself as an organization of journalists, political activists, mathematicians, and start-up company technologists, an intermediary between sources and journalists, an advocacy group for sources, and a public intelligence agency. The group has released a number of prominent document caches that exposed serious violations of human rights and civil liberties to the US and international public. Early releases included documentation of equipment expenditures and holdings in the Afghanistan war, a report about a corruption investigation in Kenya, and an operating procedures manual for the U.S. prison at Guantanamo Bay, Cuba. In April 2010, WikiLeaks released the Collateral Murder footage from the 12 July 2007 Baghdad airstrike in which Iraqi Reuters journalists were among several civilians killed. Other releases in 2010 included the Afghan War Diary and the "Iraq War Logs". The latter release allowed the mapping of 109,032 deaths in "significant" attacks by insurgents in Iraq that had been reported to Multi-National Force – Iraq, including about 15,000 that had not been previously published. In 2010, WikiLeaks also released classified diplomatic cables that had been sent to the US State Department. In April 2011, WikiLeaks began publishing 779 secret files relating to prisoners detained in the Guantanamo Bay detention camp. In 2012, WikiLeaks released the "Syria Files," over two million emails sent by Syrian politicians, corporations and government ministries. In 2015, WikiLeaks published Saudi Arabian diplomatic cables, documents detailing spying by the U.S. National Security Agency on successive French presidents, and the intellectual property chapter of the Trans-Pacific Partnership, a controversial international trade agreement which had been negotiated in secret. During the 2016 U.S. presidential election campaign, WikiLeaks released emails and other documents from the Democratic National Committee and from Hillary Clinton's campaign manager, John Podesta, showing that the party's national committee favoured Clinton over her rival Bernie Sanders in the primaries, leading to the resignation of DNC chairwoman Debbie Wasserman Schultz and an apology to Sanders from the DNC. These releases caused significant harm to the Clinton campaign, and have been attributed as a potential contributing factor to her loss in the general election against Donald Trump. The U.S. intelligence community expressed "high confidence" that the leaked emails had been hacked by Russia and supplied to WikiLeaks. WikiLeaks said that the source of the documents was not Russia or any other state. During the campaign, WikiLeaks promoted conspiracy theories about Hillary Clinton and the Democratic Party. In 2016, WikiLeaks released nearly 300,000 emails it described as coming from Turkey's ruling Justice and Development Party, later found to be taken from public mailing archives, and rereleased over 50,000 emails from the Turkish Minister of Energy and Natural Resources. In 2017, WikiLeaks published internal CIA documents describing tools used by the agency to hack devices including mobile phones and routers. In 2019, WikiLeaks published over 30,000 files as part of the Fishrot Files, exposing corruption at Samherji, a multinational fishing company based in Iceland. In October 2021, WikiLeaks' secure chat stopped working and in February 2022 their submission system and email server went offline. The organisation has been criticised for inadequately curating its content and violating the personal privacy of individuals. WikiLeaks has, for instance, revealed Social Security numbers, medical information, credit card numbers and details of suicide attempts.

3.9K
11 Oct 2022

Topic Review

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.

3.9K
30 Nov 2022

Topic Review

Science, Technology, Society and Environment Education

Science, technology, society and environment (STSE) education, originates from the science technology and society (STS) movement in science education. This is an outlook on science education that emphasizes the teaching of scientific and technological developments in their cultural, economic, social and political contexts. In this view of science education, students are encouraged to engage in issues pertaining to the impact of science on everyday life and make responsible decisions about how to address such issues (Solomon, 1993 and Aikenhead, 1994)

3.9K
20 Oct 2022

Topic Review

Palmitoylethanolamide in Autism Spectrum Disorder

Palmitoylethanolamide (PEA) is a naturally occurring saturated N-acylethanolamine that has proven to be effective in controlling inflammation, depression, epilepsy, and pain, possibly through a neuroprotective role against glutamate toxicity. Here, we systematically reviewed all human and animal studies examining PEA and its biobehavioral correlates in ASD. Studies indicate altered serum/brain levels of PEA and other endocannabinoids (ECBs)/acylethanolamines (AEs) in ASD. Altered PEA signaling response to social exposure and altered expression/activity of enzymes responsible for the synthesis and catalysis of ECBs/AEs, as well as downregulation of the peroxisome proliferator activated receptor-α (PPAR-α) and cannabinoid receptor target GPR55 mRNA brain expression, have been reported. Stress and exposure to exogenous cannabinoids may modulate ECBs/AEs levels and expression of candidate genes for neuropsychiatric disorders, with implications for ASD. Limited research suggests that PEA supplementation reduces overall autism severity by improving language and social and nonsocial behaviors. Potential neurobiological underpinnings include modulation of immune response, neuroinflammation, neurotrophy, apoptosis, neurogenesis, neuroplasticity, neurodegeneration, mitochondrial function, and microbiota activity, possibly through peroxisome proliferator-activated receptor-α (PPAR-α) activation.

3.9K
08 Sep 2021

Topic Review

G-Protein-Coupled Receptors

G-protein-coupled receptors (GPCRs), which make up the largest superfamily of human membrane proteins, play pivotal roles in mediating intracellular signaling and inducing cell proliferation, cell growth, and cell motility through the association and subsequent dissociation of G-proteins in response to external stimuli.

3.9K
05 Feb 2021

Topic Review

Universal Model of Cancer Transformation and Development

As a phenomenon, cancer is a disease related to multicellular evolution, i.e., cancer in general is understood to be a failure of the multicellular systems and is considered a reversal to unicellularity. Cancer cells are like unicellular organisms that benefit from ancestral-like traits. As a disease, cancer can be interpreted as (a) a destruction of cooperative behaviors underlying multicellular evolution, (b) a disruption of molecular networks established during the emergence of multicellularity or (c) an atavistic state resulting from reactivation of primitive programs typical of the earliest unicellular species. From this point of view and in accordance with the layered model of evolution of cellular functionalities, cancer transformation can occur as a result of huge disturbances or the destruction of functionalities that are located in the multicellular layer.

3.9K
06 May 2022

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