Miracle-dz/UniFAR-FTUs huggingface dataset:
IMPROVED ESTIMATION STRA TEGIES IN MULTIVARIATE MULTIPLE REGRESSION MODELS

The objective of this dissertation is to study properties of improved estimators of the parameters of interest in two different multivariate regression models, analogous to the fixed-X and random-X scenarios of multiple regression and compare the performance of these estimators with the usual least square estimator. In general, we study restricted versions of the multivariate regression problem based upon constraining the relationship between Y and X in some way where they may be known or unknown to the researcher prior to statistical analysis. Chapter two contains a study of the properties of improved estimation strategies for the parameters of interest in a capital asset pricing model under a general linear constraint. Asymptotic results of the suggested estimators include derivation of asymptotic bias, asymptotic mean square error, and asymptotic distributional risk. The asymptotic results demonstrate the superiority of the suggested estimation technique. A simulation study is conducted to assess the performance of the suggested estimators for large samples. Both simulation study and data example corroborate with the theoretical result. In Chapter three, we consider a multivariate multiple regression model when X is a fixed matrix. Here, we propose shrinkage and preliminary test estimation strategies for the matrix of regression parameters in the presence of a natural linear constraint. We examine the relative performances of the suggested estimators under the candidate subspace based on a quadratic risk function and the results are shown. A simulation study is conducted to compare the performance of the suggested estimators and two data examples are also presented. Our analytical and numerical results show that the suggested estimators perform better than the unrestricted estimator under the candidate subspace. In Chapter four, we consider a multivariate reduced rank regression model when X is random and we propose preliminary test and shrinkage estimation strategies. We investigate the asymptotic properties of the shrinkage and pretest estimators under a quadratic loss function and compare the performance of the suggested estimators under the candidate subspace and beyond. The methods are applied on a real data set for illustrative purposes and a simulation study is also presented.
Deaging of heat-treated iron-doped lead zirconate titanate ceramics

Doping strongly influences the properties of ferroelectric perovskite materials. One striking difference between donor- and acceptor-doped materials is the transition from “soft” to “hard” ferroelectric behavior. The physical reasons for this phenomenon are still unclear. The authors present measurements of the ferroelectric hysteresis and deaging behavior of iron-doped lead zirconate titanate after adjusting the defect structure by heat treatment in an oxygen-depleted atmosphere. Contrary to expectations, the introduction of extra oxygen vacancies makes the material “softer. ” This effect, which is discussed based on a model of defect dipoles, sheds new light on the unsolved problem of hardening and aging.
Linear stability analysis of wind turbine wakes performed on wind tunnel measurements

Abstract Wind tunnel measurements were performed for the wake produced by a three-bladed wind turbine immersed in uniform flow. These tests show the presence of a vorticity structure in the near-wake region mainly oriented along the streamwise direction, which is denoted as the hub vortex. The hub vortex is characterized by oscillations with frequencies lower than that connected to the rotational velocity of the rotor, which previous works have ascribed to wake meandering. This phenomenon consists of transversal oscillations of the wind turbine wake, which might be excited by the vortex shedding from the rotor disc acting as a bluff body. In this work, temporal and spatial linear stability analyses of a wind turbine wake are performed on a base flow obtained with time-averaged wind tunnel velocity measurements. This study shows that the low-frequency spectral component detected experimentally matches the most amplified frequency of the counter-winding single-helix mode downstream of the wind turbine. Then, simultaneous hot-wire measurements confirm the presence of a helicoidal unstable mode of the hub vortex with a streamwise wavenumber roughly equal to that predicted from the linear stability analysis.
Single and multiple event temporal response characteristics of ungated I2 tube systems

The output brightness temporal response of non-gated image intensifying systems was examined. Generation III gallium arsenide image intensifiers (image tubes) using the P43 and P20 phosphors were tested for image persistence, minimum event detection, and minimum event temporal separation (multiple burst testing, where "event" refers to a burst of light of determined duration and brightness). Persistence tests showed some correlation with previously published data and suggest that both phosphors (P43 and P20) display multiple stages of decay. The minimum event detection tests showed the Generation III Image Intensifier tubes capable of detecting pulses with durations in the low microsecond region and suggested that for faster test setups the tubes may have the capability to operate in the nanosecond region. Finally, the multiple burst testing shows the complex temporal nature of image tube power supplies when encountering multiple, rapid flashes of light.
Extensional viscosity of dilute polystyrene solutions: Effect of concentration and molecular weight

This paper reports a detailed investigation of the steady shear and extensional properties of mono-disperse polystyrene solutions for a range of molecular weights from 1.95 to 20 million and a range of concentrations from 69 ppm to 777 ppm. The steady shear and dynamic properties are reasonably well described by the Zimm model. The relaxation time and polymer viscosity evaluated using the Zimm model exhibit the expected scaling with concentration and molecular weight for theta solutions. In an extensional flow, these solutions show strain hardening and need about 5.5 to 6 strain units to reach steady state. The stress growth depends both on strain rate and strain. However, at moderate values of strain and when the Weissenberg number exceeds 6, the extensional stress growth depends only on total strain. The steady state extensional viscosity for each fluid was observed to depend on the magnitude of Weissenberg number (Wi). For Wi<6, the steady state extensional viscosity was observed to be an increasing fu.
Exact Constants in Approximation Theory

Preface 1. Best approximation and duality in extremal problems 2. Polynomials and spline-functions as approximating tools 3. Comparison theorems and inequalities for the norms of functions and their derivatives 4. Polynomial approximation of classes of functions with bounded r-th derivative in Lp 5. Spline approximation of classes of functions with bounded r-th derivative 6. Exact constants in Jackson inequalities 7. Approximation of classes of functions determined by modulus of continuity 8. N-widths of functional classes and closely related extremal problems Appendixes References.
Chemical change from diffused hydrogen gas to hydroxyl ion in silica glass optical fibres

The chemical change from hydrogen gas that diffuses into silica glass for optical fibres to hydroxyl function has been investigated. Hydrogen molecules that diffuse into GeO2-doped silica glass at 500°C easily change into OH ions by thermal energy, while this chemical change does not occur in pure silica glass at 500°C. Also, germanium-doped silica fibre, in which hydrogen gas is dissolved at room temperature, shows OH ion absorption loss increase with chemical change by heat treatment at above 100°C, while pure silica core fibre shows no OH ion absorption loss increase by the same treatment.
On the power of tests for multiple comparison of three normal means

Abstract This article gives theoretical reasons for the findings of a simulation study by Shaffer (1981). Two well-established procedures for multiple comparison of three normal means are compared—an F procedure and an R procedure. It turns out that for a large set of parameters the average number of rejected pairwise hypotheses is larger when the F procedure is applied. To achieve our result we have to prove a special instance of a conjecture by David, Lachenbruch, and Brandis (1972).
The Realiability of Mathematics Portfolio Scores: Lessons From the Vermont Experience

Portfolios are the centerpiece of Vermont's statewide assessment program in mathematics. During the first 2 years of this program, there was only moderate agreement among readers regarding a portfolio's quality. This quality often varied greatly across the five to seven pieces in a student's portfolio. Consequently, scores were not reliable enough to permit reporting student-level results. Increasing the number of readers per piece or the number of pieces per portfolio are not operationally feasible solutions to the score reliability problem.
Repeatability of brown adipose tissue measurements on FDG PET/CT following a simple cooling procedure for BAT activation

Brown Adipose Tissue (BAT) is present in a significant number of adult humans and can be activated by exposure to cold. Measurement of active BAT presence, activity, and volume are desirable for determining the efficacy of potential treatments intended to activate BAT. The repeatability of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) measurements of BAT presence, activity, and volume under controlled conditions has not been extensively studied. Eleven female volunteers underwent double baseline FDG PET imaging performed following a simple, regional cold intervention intended to activate brown fat. The cold intervention involved the lightly-clothed participants intermittently placing their feet on a block of ice while sitting in a cooled room. A repeat study was performed under the same conditions within a target of two weeks. FDG scans were obtained and maximum standardized uptake value adjusted for lean body mass (SULmax), CT Hounsfield units (HU), BAT metabolic volume (BMV), and total BAT glycolysis (TBG) were determined according to the Brown Adipose Reporting Criteria in Imaging STudies (BARCIST) 1.0. A Lin’s concordance correlation (CCC) of 0.80 was found for BMV between test and retest imaging. Intersession BAT SULmax was significantly correlated (r = 0.54; p < 0.05). The session #1 mean SULmax of 4.92 ± 4.49 g/mL was not significantly different from that of session #2 with a mean SULmax of 7.19 ± 7.34 g/mL (p = 0.16). BAT SULmax was highly correlated with BMV in test and retest studies (r ≥ 0.96, p < 0.001). Using a simplified ice-block cooling method, BAT was activated in the majority (9/11) of a group of young, lean female participants. Quantitative assessments of BAT SUL and BMV were not substantially different between test and retest imaging, but individual BMV could vary considerably. Intrasession BMV and SULmax were strongly correlated. The variability in estimates of BAT activity and volume on test-retest with FDG should inform sample size choice in studies quantifying BAT physiology and support the dynamic metabolic characteristics of this tissue. A more sophisticated cooling method potentially may reduce variations in test-retest BAT studies.
MAGNETIC FIELD FLUCTUATIONS OBSERVED IN THE HELIOSHEATH AND INTERSTELLAR MAGNETIC FIELD BY VOYAGER 1 AT 115.7–124.9 AU DURING 2011–2013

We discuss microscale fluctuations of the hour averages of the magnetic field B observed on a scale of one day by Voyager 1 (V1) from 2011.0 to 2012.3143 (when it was within the distant heliosheath, where the average magnetic field strength 〈B〉 = 0.17 nT) and during the interval from 2012.6503 to 2013.5855 (when it was within the interstellar plasma with 〈B〉 = 0.47 nT). In both regions, the fluctuations were primarily compressive fluctuations, varying along the average B (≈T direction in RTN coordinates). In the heliosheath, the average of the daily standard deviations (SDs) of the compressive and transverse components of B were 〈SDc〉 = 0.010 nT and 〈SDt〉 ⩽ 0.005 nT (which is the limit of the measurement). In the distant heliosheath 〈SDc〉/〈B〉 = 0.06, and the distributions of SD were skewed and highly kurtotic. The interstellar magnetic field (ISMF) strength was B = 0.48 nT, but the fluctuations were below the limit of measurement: 〈SDc〉 = 0.004 nT and 〈abs(SDt)〉 = 0.004 nT. The distributions of these interstellar SDs have skewness and kurtosis consistent with a Gaussian noise distribution. We also discuss the fluctuations of 48 s averages of B on a scale of 1 day during a 30 day interval when V1 was observing the ISMF. For the fluctuations in all three components of B, SD = 0.010 nT, which gives an upper limit on the fluctuations of the ISMF on the scales observed by V1. This SD rules out the possibility that there is significant power in electromagnetic fluctuations generated by pickup ion ring instabilities at these scales, which strongly constrains models of the IBEX ribbon.
Provocative mathematics questions: drawing attention to a lack of attention

The article investigates the role of attention in the reflective thinking of school mathematics teachers. It analyses teachers’ ability to pay attention to detail and use their mathematical knowledge. The vast majority of teachers can be expected to have an excellent knowledge of mathematical techniques. The question examined here is whether this kind of knowledge might structure their attention in such a way that the emphasis on procedures deflects their attention from the essential details. Four groups of participant teachers from New Zealand, Hong Kong, Germany and Ukraine were given a mini-test containing seven simple mathematics questions. Most questions in the test were provocative in the sense that they looked like routine questions but in fact had some catch. The results of the test were startlingcthe vast majority of the participants gave incorrect answers to most questions in the test. After the test, the participants were given a short questionnaire to reflect on their performance on the test. Their responses were analysed using the theories of selective, divided and focused attention and Mason’s concept of the discipline of noticing. Implementations of the results of the study in assessment and professional development are discussed.
Anomalously high thermoelectric figure of merit in Bi1−xSbx nanowires by carrier pocket alignment

Electronic transport calculations were carried out for Bi1−xSbx nanowires (0⩽x⩽0.30) of diameters 10 nm⩽dW⩽100 nm at 77 K. A band structure phase diagram was generated, showing the dependence of the relative band edge positions on diameter and composition. Calculations of the thermoelectric figure-of-merit (ZT) predict that the performance of Bi1−xSbx nanowires is superior to that of Bi nanowires and to that of the bulk alloy. An exceptionally high value of ZT for p-type nanowires at 77 K was found for dW∼40 nm and x∼0.13, which is explained by the coalescence in energy of up to ten valence subband edges to maximize the density-of-states at the Fermi energy.
Chrononutrition during Pregnancy and Its Association with Maternal and Offspring Outcomes: A Systematic Review and Meta-Analysis of Ramadan and Non-Ramadan Studies

Much evidence suggests that food intakes and eating patterns are major determinants of the phase of peripheral circadian clocks, and desynchronization between them is thought to contribute to the development of metabolic disorders. However, much remains to be understood about how different dimensions of chrononutrition during pregnancy affect pregnant women’s and their offspring’s health outcomes. Therefore, we systematically reviewed and integrated all emerging evidence on chrononutrition during pregnancy (including meal skipping, meal frequency, night eating, and (Ramadan) fasting) and their relationships with maternal and offspring outcomes. The results suggest that meal skipping and night eating during pregnancy were generally associated with adverse pregnancy and birth outcomes, whereas no strong conclusion could be reached for meal frequency. In our meta-analysis, Ramadan fasting did not seem to be related with birth weight or gestational age at birth, but evidence for other mother–offspring outcomes was inconsistent. To further elucidate the effect of chrononutrition factors on maternal and offspring health outcomes, larger and well-conducted prospective cohort and interventional studies are needed. In addition, information on covariates such as physical activity, sleep, diet quality and quantity, fasting days, fasting period per day, and trimester exposure should also be collected and considered during analysis.
Process latitude simulation of positive-tone litho-litho-etch double patterning

Double patterning (DP) techniques are emerging as the dominant method to achieve the 32 nm node and beyond. While several DP approaches exist, the litho-litho-etch (LLE) process is attractive for reduced manufacturing cost. [1] Previously published LLE work explored the process latitude in the "positive/negative LLE" regime, wherein the first resist layer is imaged by positive-tone resist and the second resist layer is imaged in negative-tone. [2] In this paper, simulation-based techniques are used to determine the process latitude in the "positive/positive LLE" system. By using the same resist material for first- and second-pass lithography, optical properties are nearly matched. However, a conformal barrier film or other chemical modification must be applied to inhibit the solubility of the firstpass topography and maintain immiscibility between layers. The consequences of choosing a positive-tone resist for both the first- and second-pass are investigated for target CD at 88 nm pitch. Process latitude is characterized using full resist models, reaction-diffusion kinetic solvers, including diffusion-limiting boundary conditions.
Empagliflozin in Adults with Chronic Kidney Disease (CKD): Current Evidence and Place in Therapy

Abstract Chronic kidney disease guidelines and disease modifying therapy have seen a dramatic shift in the last 5 years. The SGLT2 inhibitor class of medications has been catapulted from hyperglycemia management medications, to cardiovascular and kidney disease improvement therapies. Multiple trials looking at dedicated cardiovascular and kidney endpoints have resulted in favorable results. This review will target empagliflozin and the exciting journey that it has taken along this path. Empagliflozin has been studied for hyperglycemia, cardiovascular, and kidney hard outcome endpoints. Both patients with diabetes and without have been rigorously studied and shown surprising results. The major implications for patients on empagliflozin will be shown. Future studies and directions are highly anticipated to add to the growing knowledge of the SGLT2 inhibitor class, as well as discover possibilities for new disease states to benefit from empagliflozin.
A Review of Data and Document Clustering pertaining to various Distance Measures

Data is being generated at an increasing rate in a variety of fields as science and technology advance. The generated data are being saved for future decision-making. Data mining is the process of extracting patterns and useful information from massive amounts of data. The distance measure, which is used to calculate how different two objects are from one another, is one such instrument. We have conducted a comprehensive survey of how the distance measures behave when employed with different algorithms. Furthermore, the effectiveness and performance of some novel similarity measures proposed by other authors are investigated.
Impact of rural out-migration on poverty of households in southern Ethiopia

Abstract This study examined the impact of rural out-migration on the poverty of migrant-sending households by applying the new economics labor migration theory as a theoretical framework, and the multinomial endogenous switching regression as an analytical model in southern Ethiopia. Data were gathered from 415 sample rural households using stratified random sampling in the year 2021. The cost of basic needs approach and the Foster, Greer, and Thorbecke (FGT) method were used to establish the poverty line and create the poverty indices, respectively. The average annual food and non-food poverty lines are Birr 8997.52 and 2249.38 per adult equivalent. The incidence, depth, and severity of general poverty are 39.76, 10.11, and 3.55%, respectively, while the incidence, depth, and severity of food poverty are 34.70, 9.47, and 3.58%, respectively. When compared to other households, households with international migrants have a lower incidence, depth, and severity of poverty. The regression result of the multinomial endogenous switching model showed that international migration increases consumption per adult equivalent of households by 29.8% and is significant at the 1% level. Participation in rural-urban and international migration increases kilocalories per adult equivalent per day by 7.4 and 36.4%, respectively, in migrant-sending rural households. The findings support the new economics labor migration theory’s remittance hypothesis. Promoting access to land, capital, farm and non-farm employment, irrigation, family planning, and basic public services would improve rural household welfare and reduce the current wave of rural out-migration in Southern Ethiopia.
Genetic Variant Overlap Analysis Identifies Established and Putative Genes Involved in Pulmonary Fibrosis

In only around 40% of families with pulmonary fibrosis (PF) a suspected genetic cause can be found. Genetic overlap analysis of Whole Exome Sequencing (WES) data may be a powerful tool to discover new shared variants in novel genes for PF. As a proof of principle, we first selected unrelated PF patients for whom a genetic variant was detected (n = 125) in established PF genes and searched for overlapping variants. Second, we performed WES (n = 149) and identified novel potentially deleterious variants shared by at least two unrelated PF patients. These variants were genotyped in validation cohorts (n = 2748). In 125 unrelated patients, a potentially deleterious variant was detected in known PF genes of which 15 variants in six genes overlapped, involving 51 patients. Overlap analysis of WES data identified two novel variants of interest: TOM1L2 c.421T > C p.(Y141H) and TDP1c.1373dupG p.(S459fs*5), neither gene had been related to pulmonary fibrosis before. Both proteins were present in the alveolar epithelium. No apparent characteristics of telomere disease were observed. This study underlines the potential of searching for overlapping rare potentially deleterious variants to identify disease-associated variants and genes. A previously unreported variant was found in two putative new PF genes, but further research is needed to determine causality.
A Consistent Mass and Momentum Flux Computation Method Using Rudman-Type Technique With a CLSVOF Solver

In this paper, a computational method is presented that addresses the problem of multiphase flow characterized by phases with significant density ratio accompanied by strong shearing. The Coupled Level-Set Volume-of-Fluid (CLSVOF) technique is used for interface tracking, while the momentum transfer is coupled to that of mass by means of momentum fluxes computed using a sub-grid. This is an extended adaptation of Rudman’s volume tracking technique [1]. The new method is shown to conserve kinetic energy when applied to cases otherwise unfeasible, such as shear layer with high density ratio.Copyright © 2014 by ASME