Miracle-dz/UniFAR-FTUs huggingface dataset:
Theory of the lattice thermal conductivity in bulk and films of GaN

We report on a systematic theoretical investigation of the lattice thermal conductivity of several GaN samples (bulk and films) over a wide range of temperature, by applying Callaway's relaxation-time theory in its full form and Srivastava's scheme for anharmonic three-phonon scattering processes. The role of the usually neglected three-phonon normal-drift term has been quantified. We have attempted to quantify the role of phonon scattering by various defects and imperfections, present in the film samples, in controlling the temperature dependence of thermal conductivity. We find that except for the purest sample, the phonon-impurity scattering plays a significant role in controlling the thermal conductivity of GaN not only around the thermal-conductivity peak region but also over a very large range of temperature. It can also be predicted from our numerical study, and with available experimental results, that the highest possible thermal conductivity of bulk GaN can only be realized when point impurities such as oxygen and silicon are in small concentration (≃ 1016 cm-3 or less) and other defects are either absent (from experimental study) or present in very small concentration (our numerical study). The highest value of the room-temperature thermal conductivity is achieved for samples grown by the high-temperature and high-pressure growth technique.
The improved Riccati equation mapping method for constructing many families of exact solutions for a nonlinear partial differential equation of nanobiosciences

In this paper we apply the improved Riccati equation mapping method to construct many families of general exact solutions of a nonlinear partial differential equation involving parameters of special significant for nanobiosciences and biophysics, namely, the equation of nano-ionic currents along microtublues. Comparison between our new results and the well-known results are given. The nonlinear equation elaborated here is quite original and proposed in the context of important nanosciences problems related with cell signaling. It could be even of basic importance for explanation of congnitive processes in neurons. We can successfully recover the previously known exact solutions that have been found by other methods. The proposed method in this article can be applied to many other nonlinear partial differential equations. Key words: Improved Riccati equation mapping method, exact traveling wave solutions, nonlinear partial differential equation of nano-ionic currents along microtublues.
Efficient detrending of uniform images for accurate determination of the noise power spectrum at low frequencies

The noise power spectrum (NPS) of a digital x-ray imaging device is usually estimated from the average of periodograms of regions of interest (ROIs) in images obtained with uniform radiation fields. In order to mitigate low frequency trends, present in the images and not arising from stochastic processes, detrending methods are applied to the images before being Fourier transformed. The most common of these methods subtracts a second-order polynomial fit from the image. In this work, it is shown that the characteristics of low frequency trends can deviate from the quadratic dependence on spatial coordinates. This results in large residual trends that give rise to important correlations in the detrended images and produce an inaccurate rise of the NPS calculations at low frequencies. A new detrending method of uniform images is presented. The method operates in the subbands of a wavelet transform, removing the low frequency contents of the uniform image. To do this, the approximation subband of the highest level of the wavelet transform is cancelled. The effect on the NPS calculations for three digital detectors is shown and the importance of the parameters of the wavelet transform is discussed. The main result states that the performance of the new method improves those of two polynomial detrending methods commonly used and is close to the performance of the subtraction of uniform exposure images method. Finally, guidelines for the implementation of the procedure, like the number of levels in the wavelet decomposition, are provided. As the number of levels in the wavelet transform increases, the removal of trends is restricted to lower frequencies. The selection of the number of levels should be guided by the shape of the autocorrelation function of the detrended image, which has to resemble the shape expected from the propagation of noise through the imaging chain.
Coverage of ethics within the artificial intelligence and machine learning academic literature: The case of disabled people

ABSTRACT Disabled people are often the anticipated users of scientific and technological products and processes advanced and enabled by artificial intelligence (AI) and machine learning (ML). Disabled people are also impacted by societal impacts of AI/ML. Many ethical issues are identified within AI/ML as fields and within individual applications of AI/ML. At the same time, problems have been identified in how ethics discourses engage with disabled people. The aim of our scoping review was to better understand to what extent and how the AI/ML focused academic literature engaged with the ethics of AI/ML in relation to disabled people. Of the n = 1659 abstracts engaging with AI/ML and ethics downloaded from Scopus (which includes all Medline articles) and the 70 databases of EBSCO ALL, we found 54 relevant abstracts using the term “patient” and 11 relevant abstracts mentioning terms linked to “impair*”, “disab*” and “deaf”. Our study suggests a gap in the literature that should be filled given the many AI/ML related ethical issues identified in the literature and their impact on disabled people.
Hymenoptera Complex Associated with Myzus persicae and Hyalopterus spp. in Peach Orchards in Northeastern Spain and Prospects for Biological Control of Aphids

Aphids are a serious pest for peach crops. They have traditionally been managed with insecticides, but there is increasing concern about the risk that insecticides pose to both humans and the environment. As a first step to use biological control in aphid management, we conducted a 3-year field survey in northeastern Spain to determine which parasitoids and hyperparasitoids were most prevalent on two aphids, Myzus persicae (Sulzer) and Hyalopterus spp. Koch, the most harmful to peach trees. We collected 11 parasitoid species from M. persicae, with Aphidius matricariae (Haliday) being the most abundant. Two parasitoid species were also collected from Hyalopterus spp. , Aphidius transcaspicus Telenga and Praon volucre (Haliday). Hyperparasitoid species overlapped between these aphids but their relative abundances differed. We also discuss the possible impacts of hyperparasitoids on parasitoid populations. Our results suggest that it would be feasible to implement biocontrol methods for aphids in integrated pest management programmes in peach orchards. There are a number of primary parasitoid species associated with these aphids, and the nearby crops and wild vegetation in the vicinity and within the orchards may provide a suitable habitat for them. Additionally, some of them are commercially available and might be usable in augmentative releases.
On the strong law of large numbers

converge a.s. if and only if E|X|α < ∞, c being 0 or EX, according as α < 1 or α ≥ 1. Let us stress here that the Kolmogorov SLLN (α = 1) concerns the arithmetic (Cesàro) means being a regular method of summability, which is not the case when 0 < α < 2, α = 1. We consider a large class of summability methods, which are defined as follows. Let g be a positive, increasing function and h a positive function such that φ(y) ≡ g(y)h(y) satisfies the following conditions: (i) For some d ≥ 0, φ is strictly increasing on [d,∞) with range [0,∞). (ii) There exist C and a positive integer k0 such that φ(y + 1)/φ(y) ≤ C, y ≥ k0. (iii) There exist constants a and b such that
A First Implementation of Underwater Communications in Raw Water Using the 433 MHz Frequency Combined with a Bowtie Antenna

In 2016, there were 317 serious water pollution incidents in the UK, with 78,000 locations where businesses discharge controlled quantities of pollutants into rivers; therefore, continuous monitoring is vital. Since 1998, the environment agency has taken over 50 million water samples for water quality monitoring. The Internet of Things has grown phenomenally in recent years, reaching all aspects of our lives, many of these connected devices use wireless sensor networks to relay data to internet-connected nodes, where data can be processed, analyzed and consumed. However, Underwater wireless communications rely mainly on alternative communication methods such as optical and acoustic, with radio frequencies being an under-exploited method. This research presents real world results conducted in the Leeds and Liverpool Canal for the novel use of the 433 MHz radio frequency combined with a bowtie antenna in underwater communications in raw water, achieving distances of 7 m at 1.2 kbps and 5 m at 25 kbps.
The elegant universe : superstrings, hidden dimensions, and the quest for the ultimate theory

Brian Greene, one of the world's leading string theorists, peels away layers of mystery to reveal a universe that consists of eleven dimensions, where the fabric of space tears and repairs itself, and all matter-from the smallest quarks to the most gargantuan supernovas-is generated by the vibrations of microscopically tiny loops of energy. The Elegant Universe makes some of the most sophisticated concepts ever contemplated accessible and thoroughly entertaining, bringing us closer than ever to understanding how the universe works.
Deep learning for the detection of acquired and non-acquired skills in students' algorithmic assessments

This research is part of the Artificial Intelligence Virtual Trainer (AI-VT) project which aims to create a system that can identify the user's skills from a text by means of machine learning. AI-VT is a case-based reasoning learning support system can generate customized exercise lists that are specially adapted to user needs. To attain this outcome, the relevance of the first proposed exercise must be optimized to assist the system in creating personalized user profiles. To solve this problem, this project was designed to include a preliminary testing phase. As a generic tool, AI-VT was designed to be adapted to any field of learning. The most recent application of AI-VT was in the field of computer science specifically in the context of the fundamentals of algorithmic learning. AI-VT can and will also be useful in other disciplines. Developed in Python with the Keras API and the Tensorflow framework, this artificial intelligence-based tool encompasses a supervised learning environment, multi-label text classification techniques and deep neural networks. This paper presents and compares the performance levels of the different models tested on two different data sets in the context of computer programming and algorithms.
Improving the efficiency of unpaced production lines by unbalancing service time means

This paper investigates the benefits of deliberately unbalancing operation time means for non-automated production lines. The lines were simulated under the steady state condition, with various line lengths, buffer storage sizes, degrees of imbalance and patterns of imbalance. Output data were analysed using a set of statistical methods resulting in various conclusions being made. It was found that the best configurations are a bowl arrangement and a monotone decreasing order, with the first resulting in lower idle times and the second leading to lower average buffer levels than those of a balanced line.
Simulation Of Single Bubble Rising In LiquidUsing Front Tracking Method

Front tracking method is improved to simulate the rising and deforming of a bubble in quiescent viscous liquid under various flow regimes. The simulation results demonstrate that the current algorithm is more robust in modelling a multi-fluid system with wider ranges of the Reynolds number (1<Re<200) and the Bond number (1<Bo<200) under a high density ratio (ρl/ρb=1000) and a viscosity ratio (μl/μb=100). The new front tracking algorithm is also applied to investigate bubble rising and deforming behaviour in the various flow regimes of the “air bubble-water solution” system under effects of the Reynolds number and the Bond number, which have been explored experimentally in literature. The simulation results are compared with the experiments in aspects of bubble shape, terminal velocity and bubble wake flow pattern. Reasonable agreements are achieved in most flow regimes.
Does political risk matter for infrastructure investments? Empirical evidence

ABSTRACT Infrastructure assets are vital for economic development and integration, but they also encompass political risks. In Africa, infrastructure assets have remained a paradox where there is great potential for opportunities but very few projects get to the final phases. Adequate infrastructure can propagate the attainment of the Sustainable Development Goals whilst supporting recovery from the Covid-19 pandemic. Drawing from a longitudinal data set from 2000 to 2021 for 35 African countries, the paper empirically examined the nexus between infrastructure and political risk. Several techniques were employed to determine the dynamic effect, cointegration and causality between infrastructure and political risk. Controlling for the potential endogeneity in infrastructure the system Generalized Method of Moments, the relationship between political risk and infrastructure was ascertained. Furthermore, the ARDL-PMG was employed to determine the cointegration and causal relationship between infrastructure and political risk. The results suggest a cointegration between infrastructure assets and political risk. Infrastructure adjusts to changes in political risk to its long-run equilibrium at a speed of adjustment of 16.9 per cent. Bridging infrastructure gaps in Africa requires an extensive set of actions. Thus, the policy derivatives of our findings, suggest controlling the proliferation of political risk to support infrastructure investment.
A laboratory study of charge transfer accompanying the collision of ice crystals with a simulated hailstone

In a series of experiments, conducted inside a cold-room, clouds of small ice crystals of mean diameter 10μm were drawn at velocities between 1.5 and 18ms−1 past simulated hailstones. Two of these ice targets, side by side but under different conditions, were subjected to crystals from the same clouds simultaneously, so that the effects of various parameters on charge transfer could be isolated. The concentrations, sizes and shapes of the ice crystals were determined. A target heated radiatively with respect to the crystals became charged more negatively than an unheated target. A colder target became charged more positively. However, the magnitude of the charging did not depend on the temperature difference between target and crystals, provided this was greater than about 1 K. Attempts to find evidence of discharge-limited charging produced negative results. A strong velocity dependence of charging currents was found, but subsidiary experiments on the collection of crystals by the target suggested that this was largely due to the variation in the probability of separation of the crystals, which appeared to be close to zero at the lowest velocities employed. The effects of doping the targets with HF and NH3, and of surface roughness, were investigated and were found to be small. These results were found to be in reasonable qualitative and quantitative agreement with the predictions of the charging mechanisms proposed by Auf der Maur and Buser, involving differences in the work functions of ice surfaces of different nature. It was estimated that the charge, q', transferred in a rebounding collision between an ice crystal and a heated ice target is about 900 aC. It is shown that this is roughly compatible with the general pattern of results of other workers (with one exception) if the charging increases with the square of the diameter, d, of the small particles. There are good theoretical reasons for such a relationship, which may be described by the equation q'(aC)=5d2, for 10μm⩽d⩽200 μm. Charge transfer of this magnitude is estimated to be just sufficient to account for the electrification of thunderclouds.
Influence of trickle fertigation on growth and physiological attributes of hybrid okra [Abelmoschus esculentus (L.) Moench].

An experiment was conducted to compare the effect of conventional fertilisers and water soluble fertilisers at varying frequency interval of application on growth and physiological attributes of okra [Abelmoschus esculentus (L.) Moench]. The experiment was laid out in a Randomised Block Design with two control involving ten treatments in a factorial way and was replicated thrice. Among the treatment combinations, the plot receiving daily fertigation of water soluble fertilisers (S1F1) had recorded the maximum plant height at final harvest (136.80 cm), shortest inter nodal length (4.46 cm), maximum leaf area index (2.04) and the highest dry matter production (8.23 t ha-1). However, no significant difference could be observed for days to flowering, number of primary branches plant-1 at flowering as well as final harvest and node of first flower appearance.
Evidence of Spin Frustration in a Vanadium Diselenide Monolayer Magnet

Monolayer VSe2, featuring both charge density wave and magnetism phenomena, represents a unique van der Waals magnet in the family of metallic 2D transition‐metal dichalcogenides (2D‐TMDs). Herein, by means of in situ microscopy and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X‐ray and angle‐resolved photoemission, and X‐ray absorption, direct spectroscopic signatures are established, that identify the metallic 1T‐phase and vanadium 3d1 electronic configuration in monolayer VSe2 grown on graphite by molecular‐beam epitaxy. Element‐specific X‐ray magnetic circular dichroism, complemented with magnetic susceptibility measurements, further reveals monolayer VSe2 as a frustrated magnet, with its spins exhibiting subtle correlations, albeit in the absence of a long‐range magnetic order down to 2 K and up to a 7 T magnetic field. This observation is attributed to the relative stability of the ferromagnetic and antiferromagnetic ground states, arising from its atomic‐scale structural features, such as rotational disorders and edges. The results of this study extend the current understanding of metallic 2D‐TMDs in the search for exotic low‐dimensional quantum phenomena, and stimulate further theoretical and experimental studies on van der Waals monolayer magnets.
Comparison of a new variant of PMF with other receptor modeling methods using artificial and real sediment PCB data sets

A new variant of positive matrix factorization (PMF) is developed and compared to existing methods of PMF and eigenvalue‐based factor analysis (FA) using an artificially created data set, including environmental variability and an environmental data set. Diagnostic tools are considered for the determination of the number of significant factors for all methods. The methodology for the new method of PMF is based on a nonnegative least squares (NNLS) technique combined with iterative rotations to eliminate negative elements from the source profile and source contribution matrices. The PMF and FA methods reproduce the source profiles for the artificial data set well, and the PMF method provides realistic source profiles for the real data set, whereas the FA method does not. The new method may be able to reproduce zero values better than PMF using penalty terms, and also appears to provide a better fit for the data since the minimum value of the weighted sum of squares of residuals Q is maintained during the rotations. Copyright © 2005 John Wiley & Sons, Ltd.
On crossed products and Takai duality

The Takai duality theorem has proved to be a fundamental tool in the theory of crossed products of C*-algebras. It was inspired by Takesaki's duality theorem for crossed products of von Neumann algebras [7], so it is not surprising that the original proof [6] depended heavily on spatial techniques. Here we shall prove Takai's theorem by exploiting the universal properties of crossed products.
Discovery of the first young brown dwarf in the Serpens cluster

In this letter, we report the discovery of the rst young early L-dwarf in the Serpens cloud. It is obscured by more than ten magnitudes of visual absorption and was found during a near infrared (NIR) photometric survey of a 50 square arcmin area in the Serpens cloud, deep enough to probe the substellar domain. After selection from NIR colour-magnitude and colour-colour diagrams, its substellar nature has been conrmed by NIR spectroscopy at the VLT. We estimate the mass of this brown dwarf to be 0.05M and its age to be 3.5 Myr. From its NIR indices, we estimate its present spectral type to be L0{L3, and using a model its future spectral type to be T. This is the rst young brown dwarf ever found deeply embedded in a star formation region.
DEVELOPMENT AND EVALUATION OF PROCEDURES FOR QUANTIZING MULTIVARIATE DISTRIBUTIONS

Abstract : The approximation generated by a specific but arbitrary partition and a specific but arbitrary set of representation points is examined. A statistical measure of error is investigated. The size of the error is measured by some moment of the random variable. Such a measure involves both the geometrical properties of the partition ing in the k-dimensional space, and the probabil ity density. The approximation of the random variable is accomplished by selecting the representation points at random, independently of one another, and according to some given density function and then constructing the parti tion. In Chapter 2 we shall examine the behavior of the lower bound of the average normalized error for fixed variables is examined. The behavior of the minimum error when there is a large number of representation points is demonstrated. This extension takes into account the entropy rate of the discrete quantizing sequence. (Author)