Miracle-dz/UniFAR-FTUs huggingface dataset:
Eckhaus and zigzag instability in a chemotaxis model of multiple sclerosis

We present a theoretical and numerical study of the bifurcations of the stationary patterns supported by a chemotactic model of Multiple Sclerosis (MS). We derive the normal forms of the dynamics which allows to predict the appearance and stabilization of the emerging branches describing the concentric patterns typical of Balo's sclerosis, a very aggressive variant of MS. Spatial modulation of the Turing-type structures through a zigzag instability is also addressed. The nonlinear stage of the Eckhaus and zigzag instability is investigated numerically: defect-mediated wavenumber adjustments are recovered and the time of occurrence of phase-slips is studied as the system parameters are varied.
Considerations for E-Forensics: Insights Into Implications of Uncoordinated Technical, Organisational and Legal Responses to Illegal or Inappropriate on-line Behaviours

: The growing incidence of e-crime and computer misuse has increased demand for effective defensive and offensive solutions. Most responses have tended to focus on discrete sets of technical, organisational or legal challenges, but there is increasing recognition of the need for more integrated solutions that balance security, individual privacy and the generation of legally admissible digital evidence. More importantly, there is also proof to indicate that these fragmented approaches are impairing their own effectiveness due to the inter-relatedness of challenges faced. This research paper adopts an e-forensic approach to examine the links between technical, organisational and legal responses to the challenges posed by illegal or inappropriate on-line behaviour. The paper acknowledges some of the numerous challenges that remain unresolved in each approach and argues that future developments must be focused on integrated and balanced solutions that are calibrated to address the dynamic and multi-faceted nature of the forensic computing domain.
Obtenção de bioquerosene a partir de resíduos dos óleos de babaçu e coco via catálise heterogênea

A International Air Transport Association (IATA) estabeleceu metas de reduzir em 50% a emissao de CO2 na atmosfera em relacao a dados de 2005. Uma opcao para atingir essa meta seria o uso de biocombustivel no setor. O objetivo deste trabalho foi obter atraves da catalise heterogenea, bioquerosene proveniente dos acidos graxos constituidos quimicamente por 6 a 16 atomos de carbono destilados dos oleos residuais de babacu e coco, avalia-los com o intuito de estudar se o bioquerosene pode ser um substituinte do combustivel de aviacao, nas proporcoes adequadas, bem como contribuir cientificamente com dados para a literatura. A primeira etapa da pesquisa consistiu na obtencao destes acidos graxos (fase de topo) utilizando um sistema de destilacao fracionado a vacuo. Os resultados obtidos atraves de caracterizacao fisico-quimica para a fase de topo do oleo residual de babacu e coco, como viscosidade a 40 °C (6,62 mm2/s e 6,82 mm2/s, respectivamente) e densidade a 15 °C (904,8 kg/m3 e 904,3 kg/m3, respectivamente), mostraram que os acidos graxos (C6 a C16) podem ser um insumo para a producao de bioquerosene. Na segunda etapa foram realizadas as caracterizacoes fisico-quimicas dos catalisadores (Amberlyst® 15 e Amberlyst® BD20) atraves das analises de TG, FTIR e MEV/EDS. Alem disso, encontrou-se as melhores condicoes operacionais para a producao do bioquerosene com o metanol e o etanol utilizando um software estatistico para avaliar o planejamento experimental. O resultado da caracterizacao dos catalisadores pode identificar como sendo o acido sulfonico (HO-SO2-), o sitio ativo das resinas de troca ionicas. O estudo de otimizacao dos parâmetros mostraram que a Amberlyst® BD20 permite atingir conversoes acima de 95,5% em bioquerosene com o metanol e com o etanol conversoes acima de 90%. A etapa seguinte teve como objetivo analisar e comparar o bioquerosene produzido atraves do processo com dados encontrados na literatura e com o querosene fossil de aviacao (QAV-1), como tambem enquadrar o mesmo, atraves de misturas binarias com QAV-1, as normas de especificacao estabelecida pela ASTM para combustivel de aviacao comercial. Os resultados apresentaram similariedade com os dados encontrados na literatura e com o combustivel de aviacao comercial. Alem disso, os bioquerosenes misturados em ate 30% (m/m) com o QAV-1 apresentam propriedades dentro dos teores estabelecidos pela especificacao ASTM D1655 para querosene de aviacao comercial.
High-dimensional Linear Regression for Dependent Data with Applications to Nowcasting

Recent research has focused on $\ell_1$ penalized least squares (Lasso) estimators for high-dimensional linear regressions in which the number of covariates $p$ is considerably larger than the sample size $n$. However, few studies have examined the properties of the estimators when the errors and/or the covariates are serially dependent. In this study, we investigate the theoretical properties of the Lasso estimator for a linear regression with a random design and weak sparsity under serially dependent and/or nonsubGaussian errors and covariates. In contrast to the traditional case, in which the errors are independent and identically distributed and have finite exponential moments, we show that $p$ can be at most a power of $n$ if the errors have only finite polynomial moments. In addition, the rate of convergence becomes slower owing to the serial dependence in the errors and the covariates. We also consider the sign consistency of the model selection using the Lasso estimator when there are serial correlations in the errors or the covariates, or both. Adopting the framework of a functional dependence measure, we describe how the rates of convergence and the selection consistency of the estimators depend on the dependence measures and moment conditions of the errors and the covariates. Simulation results show that a Lasso regression can be significantly more powerful than a mixed-frequency data sampling regression (MIDAS) and a Dantzig selector in the presence of irrelevant variables. We apply the results obtained for the Lasso method to nowcasting with mixed-frequency data, in which serially correlated errors and a large number of covariates are common. The empirical results show that the Lasso procedure outperforms the MIDAS regression and the autoregressive model with exogenous variables in terms of both forecasting and nowcasting.
Building a Reliable Storage Stack

The arrangement of file systems and volume management/RAID systems, together commonly referred to as the storage stack, has remained the same for several decades, despite significant changes in hardware, software and usage scenarios. In this paper, we evaluate the traditional storage stack along three dimensions: reliability, heterogeneity and flexibility. We highlight several major problems with the traditional stack. We then present Loris, our redesign of the storage stack, and we evaluate several reliability, availability and performance aspects of Loris.
Model Fit Estimation for Multilevel Structural Equation Models

Structural equation modeling (SEM) provides an extensive toolbox to analyze the multivariate interrelations of directly observed variables and latent constructs. Multilevel SEM integrates mixed effects to examine the covariances between observed and latent variables across many levels of analysis. However, while it is necessary to consider model fit, traditional indices are largely insufficient to analyze model fit at each level of analysis. The present article reviews (a) the partially saturated model fit approach first suggested by Ryu and West and (b) an alternative model parameterization that removes the multilevel data structure. We next describe the implementation of an algorithm to compute partially saturated model fit for 2-level structural equation models in the open source SEM package, OpenMx, including verification in a simulation study. Finally, an example empirical application evaluates leading theories on the structure of affect from ecological momentary assessment data collected thrice daily for two weeks from 345 participants.
Quantum Field Theory: Spontaneous symmetry breaking and the Weinberg-Salam model

The foregoing chapters have dealt with field theories, including gauge theories, and their quantisation. The stage is now almost set for applying this knowledge to particle physics. One crucial bit of scenery, however, is still missing – the idea of ‘spontaneous breaking of symmetry’. About 1960 Nambu and Goldstone realised the significance of this notion in condensed matter physics, and Nambu in particular speculated on its application to particle physics. In 1964 Higgs pointed out that the consequences of spontaneous symmetry breaking in gauge theories are very different from those in non-gauge theories. Weinberg and Salam, building on earlier work of Glashow, then applied Higgs’ ideas to an SU(2) × U(1) gauge theory, which they claimed described satisfactorily the weak and electromagnetic interactions together, in other words, in a unified way. Serious interest was shown in this theory when 't Hooft proved, in 1971, that is was renormalisable. It has met with notable experimental successes. These matters are the concern of this chapter (with the exception of renormalisation, which we deal with in the next chapter). We begin by explaining spontaneous symmetry breaking, which, when applied to field theory, is a concept that refines our notion of the vacuum. What is the vacuum? We begin by considering two simple physical examples. First, consider the situation illustrated in Fig. 8.1. Place a thin rod of circular cross section vertically on a table, and push down on it along its length, with a force F.
A discrete-time and finite-state Markov chain based in-play prediction model for NBA basketball matches

Abstract In this article, a discrete-time and finite-state Markov chain model is developed to fit the NBA basketball data. It can be used to produce in-play prediction for basketball matches. An iterative algorithm is designed to calculate probabilities of the final score difference. Empirical study shows that the proposed model performs well, and more profoundly it can have positive return when we bet with the market.
Leader-Following Consensus for a Class of Multiple Robot Manipulators over Switching Networks by Distributed Position Feedback Control

The leader-following consensus problem for a class of multiple robot manipulators subject to a static and connected network has been studied recently by a distributed position feedback control law. In this technical note, we will further study the same problem under a switching network satisfying the jointly connected condition. Since the switching network can be disconnected at every time instant, the approach in the literature does not apply to the problem in this technical note. To deal with the disconnected switching network, we adopt the adaptive distributed observer approach to synthesize a distributed position feedback control law. It turns out that this control law solves the leader-following consensus problem for the class of multiple robot manipulators. The effectiveness of this new result is validated by an example.
An interpretive structural modelling of the features influencing researchers’ selection of reference management software

Reference management software packages are established as research software packages to help scholars organize their work, improve workflows and ultimately save time. The number of citation management software packages has increased in recent years and therefore choosing an appropriate one has become a challenge for researchers. Scholars always explore the features of an appropriate RMS prior to making an investment to invest in one. Hence, the purpose of this study was to identify and analyze the prominent features in the selection of appropriate reference management software based on an extensive literature review and further to validate this through experts’ opinions. We have utilized the valuable opinions of experts to develop a hierarchical model based on the interpretive structural modelling approach to demonstrate the contextual interrelationship among these factors. Furthermore, the Matrice d’Impacts Croisées-Multiplication Appliquée à un Classement analysis approach has been utilized to classify the identified features based on their dependences and driving power, and to validate the developed interpretive structural modelling-based conceptual model. The developed model in this study can help reference management software developers to understand the correlations among the identified features and their interdependences to further enhance the quality of their products. The academic and practical contributions of the study are discussed.
Algebraic Numbers as Product of Powers of Transcendental Numbers

The elementary symmetric functions play a crucial role in the study of zeros of non-zero polynomials in C [ x ] , and the problem of finding zeros in Q [ x ] leads to the definition of algebraic and transcendental numbers. Recently, Marques studied the set of algebraic numbers in the form P ( T ) Q ( T ) . In this paper, we generalize this result by showing the existence of algebraic numbers which can be written in the form P 1 ( T ) Q 1 ( T ) ⋯ P n ( T ) Q n ( T ) for some transcendental number T, where P 1 , … , P n , Q 1 , … , Q n are prescribed, non-constant polynomials in Q [ x ] (under weak conditions). More generally, our result generalizes results on the arithmetic nature of z w when z and w are transcendental.
Synoptic And Dynamic Climatology

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Exploring energy extraction from Kerr magnetospheres

The aim of this thesis is to reconsider energy extraction from black hole magnetospheres, and more specifically the Blandford-Znajek (BZ) process from an effective field theory (EFT) perspective. Superradiant instabilities of scalar and vector bound states in the presence of a rotating black hole will be reviewed when the inverse mass of the black hole is much smaller than the Compton wavelength of the bound state particle. Two different matching calculations will be described for the vector bound state case and the overall decay rate will be compared. Force-free electrodynamics will be motivated and discussed in the context of the BZ process. Using a perturbation expansion, the Blandford-Znajek process will be reviewed up to second order in the rotation parameter. The absolute-space/universal-time (3+1) viewpoint will be discussed and applied to the BZ process and an EFT-like description will be discussed when the black hole horizon is parametrically small. Using differential forms, a simplified framework for the BZ process will be introduced in the (3+1) formalism and the field strength F will be simplified in the slow-rotation limit up to first-order in the rotation parameter. Finally, the Blandford-Znajek process will be considered as a superradiant process in the massive vector limit and the total energy flux in this (new) regime will be compared to the known BZ energy flux.
Retarded functional differential equations with general delay structure

A differential equation of a dependent variable x with one independent variable t ∈ R is called a delay differential equation (abbrev. DDE), if the derivative of an unknown function x = x(·) at t depends on the past before t. DDEs appear in the fields of mathematical physics, population dynamics, engineering, and so on, and the way the equation depends on the past largely varies in such problems in application. In this thesis, we consider DDEs from dynamics viewpoint and propose a new proper setting as dynamical systems for DDEs. Unlike ordinary differential equations without delay, dynamical systems generated by DDEs cannot be formulated on the space of dependent variable x but on the space of histories of the unknown function x(·). We call this feature the delay structure of the dynamics of DDEs. The dynamics viewpoint of DDEs was brought by Hale (1963), who introduced the retarded functional differential equations (RFDEs) with finite delay. For a given DDE with finite delay, one can obtain an RFDE with finite delay by choosing the space of continuous initial histories with uniform topology and by defining the associated right-hand side F . However, there is no reason to restrict the space of histories to this space for other types of delays. As our new setting for DDEs, we shall treat DDEs with various types of delays in a unified way and clarify the delay structure in those dynamics. For this purpose, we introduce the RFDEs with general delay structure. Key features of our approach are that natural and crucial topological properties of the space of initial histories are identified, and that the Lipschitz condition of the right-hand side F is formulated independently from the metric structure of the space of initial histories. One of the main theorems of this thesis is a necessary and sufficient condition on the space of initial histories for which the corresponding initial value problem is well-posed for any “admissible” right-hand side of an RFDE with general delay structure. This necessary and sufficient condition for the well-posedness is sharper than similar conditions in the earlier result obtained by Hale & Kato (1978) and clarifies their meaning of their conditions. This result can be applied to the space of initial histories whose topology
A Test of Variances

Abstract A two sided test for the equality of variances from two normal populations is given which is not only completely unbiased but has also the stronger property of monotonicity. An example is given to illustrate the use of this test and the performance of this test is compared with that of the current equal tail area test. The case of one variance from a normal population is also considered. Tables are provided for carrying out these tests.
Nonmodal growth in spherical geometry

The existence of growth rates in excess of the normal mode growth rate is evidence of nonmodal growth (NG). A great number of studies have examined NG in the quasi-geostrophic (QG) framework, however few if any of them have dealt with the subject in the context of spherical geometry. In this study, spherical coordinate results are compared to Cartesian coordinate results from corresponding linear QG models. We also examine how NG varies with the length scale of the initial perturbation using several global parameters.
Pengembangan Media Pembelajaran Berbasis Audio Visual pada Materi Koloid Untuk Meningkatkan Motivasi dan Hasil Belajar Siswa SMA

Penelitian tentang pengembangan media pembelajaran berbasis audio visual pada materi koloid telah dilakukan di kelas XI MIPA4 SMA Negeri 12 Banda Aceh. Tujuan khusus penelitian ini adalah untuk meningkatkan motivasi dan hasil belajar siswa dengan menggunakan media audio visual serta menguji tingkat kelayakan dari media yang dihasilkan. Jenis penelitian yang digunakan adalah penelitian dan pengembangan (R & D) dengan menggunakan model pengembangan ADDIE. Subjek penelitian berjumlah 24 orang yang terdiri dari 8 siswa dan 16 siswi. Teknik pengumpulan data diperoleh dari angket validasi media, angket motivasi belajar dan soal tes. Instrumen yang digunakan adalah lembar validasi media, lembar angket motivasi belajar dan lembar soal tes. Teknik analisis data yang digunakan adalah penilaian kelayakan media, motivasi dan hasil belajar siswa. Hasil uji validasi media dari validator menghasilkan nilai rata-rata sebesar 86,43% termasuk dalam kategori sangat layak. Nilai rata-rata angket uji kelayakan media dari guru (respon guru) yaitu sebesar 94,28% termasuk dalam kategori sangat layak. Nilai rata-rata hasil angket motivasi belajar yaitu sebesar 86,46% termasuk dalam kategori sangat baik dan nilai rata-rata dari soal tes hasil belajar yaitu sebesar 77,02% termasuk dalam kategori tinggi. Kesimpulan dari penelitian ini adalah media pembelajaran berbasis audio visual pada materi koloid sangat layak digunakan dalam proses belajar mengajar serta dapat meningkatkan motivasi dan hasil belajar siswa.
Classification of Nonlinear Features of Uterine Electromyogram Signal Towards the Prediction of Preterm Birth

Early detection of preterm labor is important to avoid neonatal death and mortality. Uterine electromyography (UEMG) or electrohysterography is a non-invasive method of extracting electrical activity signal from the abdominal part during pregnancy, which helps in early detection. This signal can be used to classify term and preterm labors. Herein, the performances of four classifiers have been evaluated using seven nonlinear features extracted from UEMG signals. They were then compared with four features analyzed from different literature. The results show that with the Elman neural network classifier, the bi-spectrum feature, which has phase information, outperforms other features with 99.8875% accuracy, 100% sensitivity, and 99.77% specificity.
Quantification of Ammonia Emissions With High Spatial Resolution Thermal Infrared Observations From the Hyperspectral Thermal Emission Spectrometer (HyTES) Airborne Instrument

Thermal infrared spectra can provide unique information on atmospheric ammonia enhancements, including those produced by agricultural, industrial, and biomass burning sources. In this work, we develop and test a quantitative ammonia retrieval algorithm using data from the airborne hyperspectral thermal emission spectrometer (HyTES) instrument over diverse targets, including persistent ammonia sources, such as cattle feedlots and a power plant, as well as a small, smoldering wildfire. Although no formal validation was possible due to lack of collocated observations, the HyTES ammonia values over feedlots in the California San Joaquin Valley are shown to be consistent within the estimated retrieval uncertainty of $\sim$20%–50% with in situ ammonia values collected over the same facilities during the 2013 DISCOVER-AQ field campaign. HyTES also observed meter-scale thermal hot spots associated with a small wildfire in Northern Arizona, which was determined to coincide with the emission of free ammonia, presumed to originate from the fire. This very localized emission source, not visible from satellite sensors, could be resolved in HyTES imagery. The ammonia enhancement immediately downwind from the smoldering fire, before the free ammonia reacted to form aerosols, was found to be distinguishable from the background with values three to ten times smaller than ammonia enhancements from the power plant and cattle feedlots, respectively. High-resolution detection and quantification of ammonia over nonpersistent sources like wildfires from HyTES shows that it is a powerful tool that can be used to improve regional scale fire emission inventories by accounting for the presence of temporally short ammonia processes.