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Topic Review
Heart Rate Variability towards Noninvasive Glucose Measurement
Heart rate variability (HRV) is defined by the heart rate variations caused by the periodic change of heart rhythm over time in the absence of physiological activity, postural changes, and emotional stimuli. This labels HRV as a noninvasive marker of the autonomic nervous system (ANS) function. Heart rate variability (HRV) parameters can reveal the performance of the autonomic nervous system and possibly estimate the type of its malfunction, such as that of detecting the blood glucose level. 
  • 150
  • 14 Nov 2023
Topic Review
Heteroscedasticity
In statistics, a vector of random variables is heteroscedastic (or heteroskedastic; from Ancient Greek hetero "different" and skedasis "dispersion") if the variability of the random disturbance is different across elements of the vector. Here, variability could be quantified by the variance or any other measure of statistical dispersion. Thus heteroscedasticity is the absence of homoscedasticity. A typical example is the set of observations of income in different cities. The existence of heteroscedasticity is a major concern in regression analysis and the analysis of variance, as it invalidates statistical tests of significance that assume that the modelling errors all have the same variance. While the ordinary least squares estimator is still unbiased in the presence of heteroscedasticity, it is inefficient and generalized least squares should be used instead. Because heteroscedasticity concerns expectations of the second moment of the errors, its presence is referred to as misspecification of the second order. The econometrician Robert Engle was awarded the 2003 Nobel Memorial Prize for Economics for his studies on regression analysis in the presence of heteroscedasticity, which led to his formulation of the autoregressive conditional heteroscedasticity (ARCH) modeling technique.
  • 2.3K
  • 14 Oct 2022
Topic Review
Homoscedasticity
In statistics, a sequence (or a vector) of random variables is homoscedastic/ˌhoʊmoʊskəˈdæstɪk/ if all its random variables have the same finite variance. This is also known as homogeneity of variance. The complementary notion is called heteroscedasticity. The spellings homoskedasticity and heteroskedasticity are also frequently used. Assuming a variable is homoscedastic when in reality it is heteroscedastic (/ˌhɛtəroʊskəˈdæstɪk/) results in unbiased but inefficient point estimates and in biased estimates of standard errors, and may result in overestimating the goodness of fit as measured by the Pearson coefficient.
  • 820
  • 31 Oct 2022
Biography
I. J. Good
Irving John ("I. J."; "Jack") Good (9 December 1916 – 5 April 2009)[1][2] was a British mathematician who worked as a cryptologist at Bletchley Park with Alan Turing. After the Second World War, Good continued to work with Turing on the design of computers and Bayesian statistics at the University of Manchester. Good moved to the United States where he was professor at Virginia Tech. He was b
  • 605
  • 24 Nov 2022
Topic Review
Information Technology Audit
An information technology audit, or information systems audit, is an examination of the management controls within an Information technology (IT) infrastructure and business applications. The evaluation of evidence obtained determines if the information systems are safeguarding assets, maintaining data integrity, and operating effectively to achieve the organization's goals or objectives. These reviews may be performed in conjunction with a financial statement audit, internal audit, or other form of attestation engagement. IT audits are also known as automated data processing audits (ADP audits) and computer audits. They were formerly called electronic data processing audits (EDP audits).
  • 381
  • 29 Sep 2022
Topic Review
Markov Chain Applications to Education
The theory of Markov chains is a smart combination of Linear Algebra and Probability theory offering ideal conditions for modelling situations depending on random variables. Markov chains have found important applications to many sectors of the human activity. In this work a finite Markov chain is introduced representing mathematically the teaching process which is based on the ideas of constructivism for learning. Interesting conclusions are derived and a measure is obtained for the teaching effectiveness. An example on teaching the derivative to fresher university students is also presented illustrating our results.
  • 2.2K
  • 03 Dec 2020
Topic Review
Media Pluralism
Media pluralism defines the state of having a plurality of voices, opinions and analyses on media system (internal pluralism) or the coexistence of different and diverse types of medias and media support (external pluralism). Media pluralism is often recognized by international organizations and non-governmental organizations as being an essential part of a democratic state, Reporters Without Borders considers "access to a plurality of editorial lines and analyses [as] essential for citizens to be able to confront ideas, to make their own informed choices and to conduct their life freely". Expanded access to the Internet and the digital switch-over has enabled an increased availability of media content, largely through sharing and user-generated content on social media, in addition to the digital channels to which individuals have access across television and radio. The diversity of content is however accompanied by what Hallin and Mancini call polarized pluralism in a media system. According to the World Trends Report, a sharper division in the way we use news is coming up due to the interaction between consumption habits, changing economic models and technical systems. This signifies that even if multiple kinds of information and programming are available, each segmented group may only ingest one branch of the whole. The increase of Internet penetration and reliance on online sources for news is thought of to producing siloed debates. At the infrastructural level, ‘zero rating’— in which Internet or mobile service providers allow users to access specific content or applications without counting towards the user’s data ‘cap’— expands in parallel to mobile uptakes, particularly in emerging countries. Traditional business models for the news media continue to be disrupted, leading to vertical and horizontal concentration and introduction of new types of ownership. Challenges to media funding introduce new types of economic models such as pay-walls and crowd-funding initiatives. Gender is a part of media pluralism and is characterized by the under-representation of women in the media workforce, in decision-making and in media content. People with disabilities are also under-represented in the media system.
  • 1.3K
  • 09 Oct 2022
Topic Review
Mobile Technology in Tourism
The influence of mobile technology on tourism is very significant. With the support of mobile-related devices (smartphones, glasses, or other wearable devices), technology, data and services, multiple travel concepts, and travel modes including mobile tourism, smart tourism, e-tourism, and sustainable tourism have emerged or developed further. Mobile technology is touted as the next technology wave that can fundamentally change tourism and hotels. Moreover, mobile technology is playing an increasing role in the travel experience, and increasing travel research is concentrated in this field. Research findings show that, first, the research of mobile technology in tourism can be divided into three phases and to a certain extent is synchronized with the development of mobile technology. Second, in the area of social sciences, the research of mobile technology in tourism needs further exploration, which must refer to related research in the areas of Transportation and IT to expand the perspective of research. Top journal analysis, journal co-citation analysis, author co-citation analysis, and collaboration network analysis reveal the most representative journals, authors, institutions, and countries/regions in this research field. This finding provides a valuable reference for scholars in this field. Additionally, this research also grasped the hot and cutting-edge topics in this field through the analysis of keywords in this field. Finally, the clustering of co-citation references presents the knowledge base of mobile technology research in the tourism field: mobile technology, travel mode, mobile instrument, travel behavior research, mobile applications, and geo-based technology.
  • 10.1K
  • 28 Sep 2020
Topic Review
Modelling Energy Transition in Germany
The expression energy transition indicates a long-term structural change in energy systems. It is not a new phenomenon: man has made several energy transitions in his short history on Earth. One of the most significant was shifting to an energy system based on fossil fuels (coal, oil, and natural gas) from one essentially based on wood; however, since the 1980s, it has been realized that fossil fuels are at the root of climate change due to carbon emissions into the atmosphere.
  • 482
  • 20 Apr 2022
Topic Review
Optimal Interpolation for infrared satellite data
Thermal infrared remote sensing measurements are blinded to surface emissions under cloudiness because infrared sensors cannot penetrate thick cloud layers. Therefore, surface and atmospheric parameters can be retrieved only in clear sky conditions giving origin to spatial fields flagged with missing pieces of information. Motivated by this we present a methodology to retrieve missing values of some interesting geophysical variables retrieved from spatially scattered infrared satellite observations in order to yield level 3 (L3), regularly gridded, data. The technique is based on a 2-Dimensional (2D) Optimal Interpolation (OI) scheme. The goodness of the approach has been tested on 15-min temporal resolution Spinning Enhanced Visible and Infrared Imager (SEVIRI) emissivity and surface temperature (ST) products over South Italy (land and sea), on Infrared Atmospheric Sounding Interferometer (IASI) atmospheric ammonia (NH3) concentration over North Italy and carbon monoxide (CO), sulfur dioxide (SO2) and NH3 concentrations over China. Sea surface temperature (SST) retrievals have been compared with gridded data from MODIS (Moderate-resolution Imaging Spectroradiometer) observations. For gases concentration, we have considered data from 3 different emission inventories, that is, Emissions Database for Global Atmospheric Research v3.4.2 (EDGARv3.4.2), the Regional Emission inventory in ASiav3.1 (REASv3.1) and MarcoPolov0.1, plus an independent study.
  • 708
  • 30 Oct 2020
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