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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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Midwest Rail Rangers
Midwest Rail Rangers is a 501(c)(3) non-profit organization whose mission is to present on-board educational programs to railroad passengers in the Midwestern United States regarding such topics as history, ecology, and geology. Interpretive Guides with Midwest Rail Rangers provide interpretive programs on-board the South Shore Line between Chicago, Illinois and South Bend, Indiana two to three weekends per month, year-round. The Midwest Rail Rangers also partner with the Wisconsin Great Northern Railroad to present history talks aboard their Sky Parlour Car, a former Atchison, Topeka and Santa Fe Railway ("Santa Fe") Hi-Level lounge car / Amtrak Pacific Parlour Car. Guides with the organization also present educational programs several times per year on private rail excursions featuring heritage railroad equipment from the 1950s and 1960s, group rail charters on Amtrak organized by the 20th Century Railroad Club of Chicago, and at various railroad museums and train shows. The organization is operated out of Barron, Wisconsin, however most guides living in the Chicago or Milwaukee areas.
  • 678
  • 28 Oct 2022
Topic Review
Aflatoxin
Aflatoxins are poisonous carcinogens that are produced by certain molds (Aspergillus flavus and Aspergillus parasiticus) which grow in soil, decaying vegetation, hay, and grains. They are regularly found in improperly stored staple commodities such as cassava, chili peppers, corn, cotton seed, millet, peanuts, rice, sesame seeds, sorghum, sunflower seeds, tree nuts, wheat, and a variety of spices. When contaminated food is processed, aflatoxins enter the general food supply where they have been found in both pet and human foods, as well as in feedstocks for agricultural animals. Animals fed contaminated food can pass aflatoxin transformation products into eggs, milk products, and meat. For example, contaminated poultry feed is suspected in the findings of high percentages of samples of aflatoxin-contaminated chicken meat and eggs in Pakistan. Children are particularly affected by aflatoxin exposure, which is associated with stunted growth, delayed development, liver damage, and liver cancer. An association between childhood stunting and aflatoxin exposure has been reported in some studies but could not be detected in all. Furthermore, a causal relationship between childhood stunting and aflatoxin exposure has yet to be conclusively shown by epidemiological studies, though such investigations are underway. Adults have a higher tolerance to exposure, but are also at risk. No animal species is immune. Aflatoxins are among the most carcinogenic substances known. After entering the body, aflatoxins may be metabolized by the liver to a reactive epoxide intermediate or hydroxylated to become the less harmful aflatoxin M1. Aflatoxins are most commonly ingested. However the most toxic type of aflatoxin, B1, can permeate through the skin. The United States Food and Drug Administration (FDA) action levels for aflatoxin present in food or feed is 20 to 300 ppb. The FDA has had occasion to declare both human and pet food recalls as a precautionary measure to prevent exposure. The term "aflatoxin" is derived from the name of one of the molds that produce it, Aspergillus flavus. It was coined around 1960 after its discovery as the source of "Turkey X disease". Aflatoxins form one of the major groupings of mycotoxins.
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  • 28 Oct 2022
Topic Review
Proto-Norse Language
Proto-Norse (also called Proto-Scandinavian, Proto-Nordic, Ancient Scandinavian, Proto-North Germanic and a variety of other names) was an Indo-European language spoken in Scandinavia that is thought to have evolved as a northern dialect of Proto-Germanic in the first centuries CE. It is the earliest stage of a characteristically North Germanic language, and the language attested in the oldest Scandinavian Elder Futhark inscriptions, spoken from around the 2nd to the 8th centuries CE (corresponding to the late Roman Iron Age and the Germanic Iron Age). It evolved into the dialects of Old Norse at the beginning of the Viking Age around 800 CE, which later themselves evolved into the modern North Germanic languages (Faroese, Icelandic, the three Continental Scandinavian languages, and their dialects).
  • 3.1K
  • 28 Oct 2022
Topic Review
Principles of Grid Generation
Grids or meshes are geometrical shapes (formed after discretisation of the geometric domain) which are small-sized discrete cells that cover the physical domain, whose objective is to identify the discrete volumes or elements where conservation laws can be applied. They have applications in the fields of computational fluid dynamics (CFD), geography, designing and many more places where numerical solutions to the partial differential equations (PDEs) are required. Numerical grid generation is the crucial initial step involved in computing numerical solutions to the equations that describe a physical process. The accuracy of the solution depends upon the quality of the grid generated. A well-constructed grid can improve the quality of solution whereas, deviations from the numerical solution can be observed with a poorly constructed grid. Techniques for creating the cell forms the basis of grid generation. Various methods for the grid generation are discussed below.
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  • 28 Oct 2022
Topic Review
Image Derivatives
Image derivatives can be computed by using small convolution filters of size 2 x 2 or 3 x 3, such as the Laplacian, Sobel, Roberts and Prewitt operators. However, a larger mask will generally give a better approximation of the derivative and examples of such filters are Gaussian derivatives and Gabor filters. Sometimes high frequency noise needs to be removed and this can be incorporated in the filter so that the Gaussian kernel will act as a band pass filter. The use of Gabor filters in image processing has been motivated by some of its similarities to the perception in the human visual system. The pixel value is computed as a convolution where [math]\displaystyle{ \mathbf{d} }[/math] is the derivative kernel and [math]\displaystyle{ G }[/math] is the pixel values in a region of the image and [math]\displaystyle{ \ast }[/math] is the operator that performs the convolution.
  • 1.4K
  • 28 Oct 2022
Topic Review
Mercedes-Benz CLA-Class
The Mercedes-Benz CLA class is a series of luxury compact executive cars manufactured by Mercedes-Benz since 2013. The first generation was a four-door sedan based on the platform of the W176 A-Class and W246 B-Class compact cars, marketed as a four-door coupé. In 2015, Mercedes-Benz expanded the CLA family to include the Shooting Brake, a station wagon configuration. As the V177 A-Class sedan took its place as the budget-conscious sedan, the second generation got longer and wider than the W205 C-Class. The CLA is Mercedes-Benz's first front-wheel drive vehicle offered in the North American market. The CLA range is positioned above the A-Class and it is nearly on the level of the C-Class in the Mercedes model range, and models tend to be less practical than the A-Class it is based on. The CLA first went on sale in Europe in April 2013, and was subsequently introduced in the United States in September 2013. Its largest markets are Western Europe and the United States. Global cumulative CLA sales reached 100,000 during its first year, cited as "our best launch in 20 years" by Mercedes-Benz. Worldwide, Mercedes-Benz sold about 750,000 units of the first generation.
  • 9.0K
  • 28 Oct 2022
Topic Review
Structural Family Therapy
Structural family therapy (SFT) is a method of psychotherapy developed by Salvador Minuchin which addresses problems in functioning within a family. Structural family therapists strive to enter, or "join", the family system in therapy in order to understand the invisible rules which govern its functioning, map the relationships between family members or between subsets of the family, and ultimately disrupt dysfunctional relationships within the family, causing it to stabilize into healthier patterns. Minuchin contends that pathology rests not in the individual, but within the family system. SFT utilizes, not only a special systems terminology, but also a means of depicting key family parameters diagrammatically. Its focus is on the structure of the family, including its various substructures. In this regard, Minuchin is a follower of systems and communication theory, since his structures are defined by transactions among interrelated systems within the family. He subscribes to the systems notions of wholeness and equifinality, both of which are critical to his notion of change. An essential trait of SFT is that the therapist actually enters, or "joins", with the family system as a catalyst for positive change. Joining with a family is a goal of the therapist early on in his or her therapeutic relationship with the family. Structural and Strategic therapy are important therapeutic models to identify as many therapists use these models as the bases for treatment. Each model has its own approach using different ways in conceptualizing a problem and developing treatment plans that support the goals stated for therapy. In addition, theory-based treatment plans are the source for goal development and treatment options by identifying the presenting problem and social influences. Both these models use similar approaches and define goals with various therapeutic processes that begin with the building of therapist and client relationship. In addition, diversity and theory are identified as a major component in choosing a theory that addresses diversity issues.
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  • 28 Oct 2022
Topic Review
Burgess Shale Type Preservation
The Burgess Shale of British Columbia is famous for its exceptional preservation of mid-Cambrian organisms. Around 40 other sites have been discovered of a similar age, with soft tissues preserved in a similar, though not identical, fashion. Additional sites with a similar form of preservation are known from the Ediacaran and Ordovician periods. These various shales are of great importance in the reconstruction of the ecosystems immediately after the Cambrian explosion. The taphonomic regime results in soft tissue being preserved, which means that organisms without hard parts that could be conventionally fossilised can be seen; also, we gain an insight into the organs of more familiar organisms such as the trilobites. The most famous localities preserving organisms in this fashion are the Canadian Burgess Shale, the Chinese Chengjiang fauna, and the more remote Sirius Passet in north Greenland. However, a number of other localities also exist.
  • 1.1K
  • 28 Oct 2022
Topic Review
Ada Semantic Interface Specification
The Ada Semantic Interface Specification (ASIS) is a layered, open architecture providing vendor-independent access to the Ada Library Environment. It allows for the static analysis of Ada programs and libraries. It is an open, published interface library that consists of the Ada environment and their tools and applications. As explained by the ASIS Working Group: “ASIS is an interface between an Ada environment as defined by ISO/IEC 8652:1995 (the Ada Reference Manual) and any tool requiring information from this environment” (SIGAda, 2020) It is exclusively used for programming language applications and static analysis on Ada programs, therefore giving the relevant information and access to Computer-aided software engineering (CASE) and applicable developers. ASIS also has the ability in utilizing the relevant software engineering tools whilst also embodying an easy understanding of the complexities of an Ada environment display. In addition, it provides procedures, functions and relevant information that can be significantly used to access exclusive information found in reference manuals and the Abstract Syntax Tree (AST). Which in return will advance ASIS to the capability of being portable to transport and retain information and terminology of Ada tools. “ASIS consists of 21 packages, 2 are optional and within these packages define 349 queries”. ASIS will also consist of a package which within it includes child packages that include “Errors Compilation units, Ada environments, implementation, exceptions, elements, iterator, declarations, expressions, clauses, definitions, statements, text and Ids”. Overall ASIS is simply a straightforward way to collect data from an ADA program and increases any of the Ada tools portability.
  • 660
  • 28 Oct 2022
Topic Review
Naturalness
In physics, naturalness is the property that the dimensionless ratios between free parameters or physical constants appearing in a physical theory should take values "of order 1" and that free parameters are not fine-tuned. That is, a natural theory would have parameter ratios with values like 2.34 rather than 234000 or 0.000234. The requirement that satisfactory theories should be "natural" in this sense is a current of thought initiated around the 1960s in particle physics. It is a criterion that arises from the seeming non-naturalness of the standard model and the broader topics of the hierarchy problem, fine-tuning, and the anthropic principle. However it does tend to suggest a possible area of weakness or future development for current theories such as the Standard Model, where some parameters vary by many orders of magnitude, and which require extensive "fine-tuning" of their current values of the models concerned. The concern is that it is not yet clear whether these seemingly exact values we currently recognize, have arisen by chance (based upon the anthropic principle or similar) or whether they arise from a more advanced theory not yet developed, in which these turn out to be expected and well-explained, because of other factors not yet part of particle physics models. The concept of naturalness is not always compatible with Occam's razor, since many instances of "natural" theories have more parameters than "fine-tuned" theories such as the Standard Model. Naturalness in physics is closely related to the issue of fine-tuning, and over the past decade many scientists argued that the principle of naturalness is a specific application of Bayesian statistics. In the history of particle physics, the naturalness principle has given correct predictions three times - in the case of electron self-energy, pion mass difference and kaon mass difference.
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  • 28 Oct 2022
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