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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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Meo (Telecommunication Service)
MEO is a mobile and fixed telecommunications service and brand from Altice Portugal (formerly Portugal Telecom), managed by MEO - Serviços de Comunicações e Multimédia. The service was piloted in Lisbon in 2006 and was later extended to Porto and Castelo Branco.
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  • 03 Nov 2022
Topic Review
General Atomics Avenger
The General Atomics Avenger (formerly Predator C) is a developmental unmanned combat air vehicle built by General Atomics Aeronautical Systems for the U.S. military.
  • 3.5K
  • 03 Nov 2022
Topic Review
Self-confrontation Psychology
Self-Confrontation psychology is a technique for examining people's behavior modification. This process can be called Self-Confrontation Method(SCM). It relies on people's inconsistent knowledge and dissatisfaction with their own values, motivation, behaviors, or with their personal systems and those of significant others to make a change that patient needs to change. Self-Confrontation Psychology is based on two theories which are Valuation Theory and Dialogical-Self Theory.
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  • 03 Nov 2022
Topic Review
Passivation
Passivation, in physical chemistry and engineering, refers to coating a material so it becomes "passive", that is, less readily affected or corroded by the environment. Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build by spontaneous oxidation in the air. As a technique, passivation is the use of a light coat of a protective material, such as metal oxide, to create a shield against corrosion. Passivation of silicon is used during fabrication of microelectronic devices. In electrochemical treatment of water, passivation reduces the effectiveness of the treatment by increasing the circuit resistance, and active measures are typically used to overcome this effect, the most common being polarity reversal, which results in limited rejection of the fouling layer.[clarification needed] When exposed to air, many metals naturally form a hard, relatively inert surface layer, usually an oxide (termed the "native oxide layer") or a nitride, that serves as a passivation layer. In the case of silver, the dark tarnish is a passivation layer of silver sulfide formed from reaction with environmental hydrogen sulfide. (In contrast, metals such as iron oxidize readily to form a rough porous coating of rust that adheres loosely and sloughs off readily, allowing further oxidation.) The passivation layer of oxide markedly slows further oxidation and corrosion in room-temperature air for aluminium, beryllium, chromium, zinc, titanium, and silicon (a metalloid). The inert surface layer formed by reaction with air has a thickness of about 1.5 nm for silicon, 1–10 nm for beryllium, and 1 nm initially for titanium, growing to 25 nm after several years. Similarly, for aluminium, it grows to about 5 nm after several years. Surface passivation refers to a common semiconductor device fabrication process critical to modern electronics. It is the process by which a semiconductor surface such as silicon is rendered inert, and does not change semiconductor properties when it interacts with air or other materials. This is typically achieved by thermal oxidation, in which the material is heated and exposed to oxygen. In a silicon semiconductor, this process allows electricity to reliably penetrate to the conducting silicon below the surface, and to overcome the surface states that prevent electricity from reaching the semiconducting layer. Surface passivation by thermal oxidation is one of the key features of silicon technology, and is dominant in microelectronics. The surface passivation process was developed by Mohamed M. Atalla at Bell Labs in the late 1950s. It is commonly used to manufacture MOSFETs (metal-oxide-semiconductor field-effect transistors) and silicon integrated circuit chips (with the planar process), and is critical to the semiconductor industry. Surface passivation is also critical to solar cell and carbon quantum dot technologies.
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  • 03 Nov 2022
Topic Review
Trade Adjustment Assistance
Trade Adjustment Assistance (TAA) is a federal program of the United States government to act as a way to reduce the damaging impact of imports felt by certain sectors of the U.S. economy. The current structure features four components of Trade Adjustment Assistance: for workers, firms, farmers, and communities. Each cabinet-level department was tasked with a different sector of the overall Trade Adjustment Assistance program. The program for workers is the largest, and administered by the U.S. Department of Labor. The program for farmers is administered by the U.S. Department of Agriculture, and the firms and communities programs are administered by the U.S. Department of Commerce.
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  • 03 Nov 2022
Topic Review
Training, Test, and Validation Sets
In machine learning, the study and construction of algorithms that can learn from and make predictions on data is a common task. Such algorithms work by making data-driven predictions or decisions,:2 through building a mathematical model from input data. The data used to build the final model usually comes from multiple datasets. In particular, three data sets are commonly used in different stages of the creation of the model. The model is initially fit on a training dataset, that is a set of examples used to fit the parameters (e.g. weights of connections between neurons in artificial neural networks) of the model. The model (e.g. a neural net or a naive Bayes classifier) is trained on the training dataset using a supervised learning method (e.g. gradient descent or stochastic gradient descent). In practice, the training dataset often consist of pairs of an input vector and the corresponding "answer" vector (or scalar), which is commonly denoted as the target (or label). The current model is run with the training dataset and produces a result, which is then compared with the target, for each input vector in the training dataset. Based on the result of the comparison and the specific learning algorithm being used, the parameters of the model are adjusted. The model fitting can include both variable selection and parameter estimation. Successively, the fitted model is used to predict the responses for the observations in a second dataset called the validation dataset. The validation dataset provides an unbiased evaluation of a model fit on the training dataset while tuning the model's hyperparameters (e.g. the number of hidden units in a neural network). Validation datasets can be used for regularization by early stopping: stop training when the error on the validation dataset increases, as this is a sign of overfitting to the training dataset. This simple procedure is complicated in practice by the fact that the validation dataset's error may fluctuate during training, producing multiple local minima. This complication has led to the creation of many ad-hoc rules for deciding when overfitting has truly begun. Finally, the test dataset is a dataset used to provide an unbiased evaluation of a final model fit on the training dataset.. When the data in the test dataset has never been used in training (for example in cross-validation), the test dataset is also called a holdout dataset.
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  • 03 Nov 2022
Topic Review
Comparison of Numerical Analysis Software
The following tables provide a comparison of numerical analysis software.
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  • 03 Nov 2022
Topic Review
Back Dorm Boys
The Back Dorm Boys is a Chinese duo who gained fame for their lip sync videos to songs by the Backstreet Boys and other pop stars. Their videos, captured on a low quality Web cam in their college dorm room, have been viewed by Internet users within China and around the world. Many of their videos can be seen on YouTube, giving them YouTube fame. The two, Wei Wei (simplified Chinese: 韦炜; traditional Chinese: 韋煒; pinyin: Wéi Wěi) and Huang Yixin (simplified Chinese: 黄艺馨; traditional Chinese: 黃藝馨; pinyin: Huáng Yìxīn), were sculpture majors at the Guangzhou Academy of Fine Arts (simplified Chinese: 广州美术学院; traditional Chinese: 廣州美術學院; pinyin: Gǔangzhōu Měishù Xuéyuàn). The Dormitory Boys, a blog of note on Blogger, which some believe is not maintained by the Back Dorm Boys, but written by a ghostwriter, took requests, asking fans to recommend a song they should lip sync to. In January 2006, a poll was conducted from songs picked from 427 requests received 2005, December. The Black Eyed Peas' song "My Humps" won the poll, but the Back Dorm Boys lip synced to the song "Don't Lie" by the Black Eyed Peas instead, which was a huge hit on YouTube as well as their host country. They are apparently producing a drama, according to their official blog. They are featured in one Mainland China sitcom, or drama, called Nonstop (青春进行时).
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  • 03 Nov 2022
Topic Review
Science Moms
Science Moms is a 2017 American documentary film about mothers who advocate for science-based decision-making concerning the health and nutrition of children. The film covers vaccines, autism, celebrity-endorsed health fads, cancer, allergies, organic food, GMOs, homeopathy, and the appeal to nature fallacy. Originally only available by direct download for a fee from the Science Moms website, in May 2018, the full film was posted to the Science Moms YouTube channel for free viewing.
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  • 03 Nov 2022
Topic Review
Margin
In finance, margin is the collateral that a holder of a financial instrument has to deposit with a counterparty (most often their broker or an exchange) to cover some or all of the credit risk the holder poses for the counterparty. This risk can arise if the holder has done any of the following: The collateral for a margin account can be the cash deposited in the account or securities provided, and represents the funds available to the account holder for further share trading. On United States futures exchanges, margins were formerly called performance bonds. Most of the exchanges today use SPAN ("Standard Portfolio Analysis of Risk") methodology, which was developed by the Chicago Mercantile Exchange in 1988, for calculating margins for options and futures.
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