1,720,961 research outputs found
The Physics Behind Electronics
No full textThis book is not simply about electronics but rather a thorough exploration of physics. Instead of isolating electronics as an art, its primary goal is to explain the physical principles behind electronic circuits and how they are applied practically. Electronics provides a framework for understanding physics, and vice versa.
It is intended for advanced undergraduate or graduate students in physics or related fields who have a basic grasp of electromagnetism and calculus. It also caters to individuals with practical electronics knowledge looking to deepen their understanding of often overlooked concepts.
While traditional textbooks treat electronics as a set of techniques, the growing availability of affordable acquisition boards and user-friendly software has diminished the need for expertise in circuit design. Nonetheless, physicists still need to comprehend concepts like stability, impedance matching, noise, and the advantages and limitations of signal sampling.
Starting with linear time-invariant systems and feedback, the book progresses to designing circuits using operational amplifiers and oscillators, covering stability and dissipation. It also delves into the Nyquist-Shannon theorem and the basics of digital electronics, emphasizing state-sensitive and clock-sensitive operators. Additionally, it offers an overview of electronic devices facilitating analog-to-digital conversion.
The book concludes by examining scenarios involving high frequencies where wires act as waveguides and addressing noise sources from thermal agitation and the corpuscular nature of current. Theoretical concepts are reinforced with solved exercises, and practical "in-the-lab" sections guide readers through experiments using affordable kits and instruments, requiring minimal electronic prototyping knowledge
Kramers–Kronig relations via Laplace formalism and L^1 integrability
Full text linkKramers–Kronig relations link the real and imaginary parts of the Fourier transform of a well-behaved causal transfer function describing a linear, time-invariant system. From the physical point of view, according to the Kramers–Kronig relations, absorption and dispersion become two sides of the same coin. Due to the simplicity of the assumptions underlying them, the relations are a cornerstone of physics. The rigorous mathematical proof was carried out by Titchmarsh in 1937 and just requires the transfer function to be square-integrable (L^2), or equivalently that the impulse response of the system at hand has a finite energy. Titchmarsh’s proof is definitely not easy, thus leading to crucial steps that are often overlooked by instructors and, occasionally, prompting some authors to attempt shaky shortcuts. Here, we share a rigorous mathematical proof that relies on the Laplace formalism and requires a slightly stronger assumption on the transfer function, namely it
being Lebesgue-integrable (L^1). While the result is not as general as Titchmarsh’s proof, its enhanced simplicity makes a deeper knowledge of the mathematical aspects of the Kramers–Kronig relations more accessible to the audience of physicists
Measuring the Rate of Information Exchange in Point-Process Data With Application to Cardiovascular Variability
Full text linkThe amount of information exchanged per unit of time between two dynamic processes is
an important concept for the analysis of complex systems. Theoretical formulations and
data-efficient estimators have been recently introduced for this quantity, known as the
mutual information rate (MIR), allowing its continuous-time computation for event-based
data sets measured as realizations of coupled point processes. This work presents the
implementation of MIR for point process applications in Network Physiology and
cardiovascular variability, which typically feature short and noisy experimental time
series. We assess the bias of MIR estimated for uncoupled point processes in the
frame of surrogate data, and we compensate it by introducing a corrected MIR (cMIR)
measure designed to return zero values when the two processes do not exchange
information. The method is first tested extensively in synthetic point processes
including a physiologically-based model of the heartbeat dynamics and the blood
pressure propagation times, where we show the ability of cMIR to compensate the
negative bias of MIR and return statistically significant values even for weakly coupled
processes. The method is then assessed in real point-process data measured from
healthy subjects during different physiological conditions, showing that cMIR between
heartbeat and pressure propagation times increases significantly during postural stress,
though not during mental stress. These results document that cMIR reflects physiological
mechanisms of cardiovascular variability related to the joint neural autonomic modulation
of heart rate and arterial compliance
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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