Miracle-dz/UniFAR-FTUs huggingface dataset:
Quantum spin dynamics at terahertz frequencies in 2D hole gases and improper ferroelectrics

Terahertz time-domain spectroscopy permits the excitations of novel materials to be examined with exquisite precision. Improper ferroelectric materials such as cupric oxide (CuO) exhibit complex magnetic ground states. CuO is antiferromagnetic below 213K, but has an incommensurate cycloidal magnetic phase between 213K and 230K. Remarkably, the cycloidal magnetic phase drives ferroelectricity, where the material becomes polar. Such improper multiferroics are of great contemporary interest, as a better understanding of the science of magnetoelectric materials may lead to their application in actuators, sensors and solid state memories. Improper multiferroics also have novel quasiparticle excitations: electromagnons form when spin-waves become electric-dipole active. By examining the dynamic response of spins as they interact with THz radiation we gain insights into the underlying physics of multi-ferroics. In contrast to improper ferroelectrics, where magnetism drives structural inversion asymmetry (SIA), two-dimensional electronic systems can exhibit non-degenerate spin states as a consequence of SIA created by strain and/or electric fields. We identify and explore the influence of the Rashba spin-orbit interaction upon cyclotron resonance at terahertz frequencies in high-mobility 2D hole gases in germanium quantum wells. An enhanced Rashba spin-orbit interaction can be linked to the strain of the quantum well, while a time-frequency decomposition method permitted the dynamical formation and decay of spin-split cyclotron resonances to be tracked on picosecond timescales. Long spin-decoherence times concurrent with high hole mobilities highlight the potential of Ge quantum wells in spintronics.
Dublin Radiocarbon Dates I

A C14-dating installation was operated in the Physics Department, Trinity College, Dublin, from early 1958 until early 1960, by I. R. McAulay. Construction and testing of the apparatus had occupied 15 months previous to this. Material for dating was selected and pretreated by W. A. Watts, who also collected and submitted the samples and carried out pollen analyses except where the contrary is stated in the text. The project was a short-term one with two main aims; to obtain a few key archaeologic dates, particularly in the Neolithic, to help orientate chronologic discussion; and to test the validity of the pollen zonation for the post-Atlantic of Mitchell (1956).
DIGITAL IMAGE COMPRESSION TECHNIQUES

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Higher spin dirac operators in two vector variables in Clifford analysis

The aim of this doctoral thesis is to study the construction and some properties of a speci c higher spin Dirac operator in Cliff ord analysis. In general, a higher spin Dirac operator D is the unique (up to a multiplicative constant) elliptic conformally invariant fi rst-order di fferential operator acting on differentiable functions with values in a vector space V which is an irreducible representation of Spin(m) with a specific highest weight and which can be realised in Clifford analysis as a vector space of polynomials in several vector variables, called the simplicial monogenic polynomials. Higher spin Dirac operators in Cliff ord analysis can be seen as a generalisation of the standard Dirac operator, whose functiontheorical properties lie at the heart of many results in Cliff ord analysis. In its turn, the standard Dirac operator can be seen as the generalisation of the Cauchy-Riemann operator in the complex plane. The above-mentioned speci fic higher spin Dirac operator that plays the main role in this thesis, presents complications that were not yet discovered, even though explicit examples of higher spin Dirac operators have been studied before. Its function-theoretical properties are studied and its homogeneous polynomial null solutions (of a fixed degree) will be discussed. We can reveal right now that the vector space of these null solutions is no longer irreducible with respect to the Spin group, contrary to the case of the standard Dirac operator. It appears that this remains true for other higher spin Dirac operators, which makes the study of these operators complicated. Therefore, an important part of this thesis was to describe the decomposition of this kernel space into Spin(m)-irreducibles summands, which we have labeled by their highest weight. This decomposition is proved by induction. The decomposition of the kernel space into these irreducibles can be visualised in an aesthetically pleasing way. At that point in the thesis it is known how the vector space of h-homogeneous null solutions of our operator behaves under the action of the Spin group. We have tried to solve this problem.
Interplay between electron correlations and quantum orders in the Hubbard model

Interplay between electron correlations and quantum orders in the Hubbard model William Witczak-Krempa Doctor of Philosophy Graduate Department of Physics University of Toronto 2013 We discuss the appearance of quantum orders in the Hubbard model for interacting electrons, at half-filling. Such phases do not have local order parameters and need to be characterized by the quantum mechanical properties of their ground state. On one hand, we study the Mott transition from a metal to a spin liquid insulator in two dimensions, of potential relevance to some layered organic compounds. The correlation-driven transition occurs at fixed filling and involves fractionalization of the electron: upon entering the insulator, a Fermi surface of neutral spinons coupled to an internal gauge field emerges. We focus on the transport properties near the quantum critical point and find that the emergent gauge fluctuations play a key role in determining the universal scaling. Second, motivated by a class of three-dimensional transition metal oxides, the pyrochlore iridates, we study the interplay of non-trivial band topology and correlations. Building on the strong spin orbit coupling in these compounds, we construct a general microscopic Hubbard model and determine its mean-field phase diagram, which contains topological insulators, Weyl semimetals, axion insulators and various antiferromagnets. We also discuss the effects many-body correlations on theses phases. We close by examining a fractionalized topological insulator that combines the two main themes of the thesis: fractionalization and non-trivial band topology. Specifically, we study how the twodimensional protected surface states of a topological Mott insulator interact with a threedimensional emergent gauge field. Various correlation effects on observables are identified.
Glasgow University Radiocarbon Measurements I

Two radiocarbon counting systems have been established in the Chemistry Department, University of Glasgow, since late 1967. The counting gas is methane, at pressures up to 10 atm, and 2 alternative procedures are followed for methane production, (a) high pressure synthesis in a stainless steel 4.5 1 reactor and (b) low pressure synthesis in an all glass flow-reactor. Both systems employ 0.5% ruthenium on alumina pellets as catalyst (Engelhard Industries Ltd.). Early samples synthesized with Air Products' hydrogen showed evidence of tritium contamination. This gas supply was later replaced with tritium-free hydrogen supplied by Messrs. Griesheim, Düsseldorf, Germany. Both detectors used for routine measurements are 0.5 1 internal gas counters supplied by Beckman Instruments Inc., California. The detectors are surrounded by a concentric-wall multiple anode anticoincidence counter. The entire counter assembly is encased within a 4-in. -thick lead shield manufactured from aged lead by J. Girdler and Co., London. Counter electronics, anticoincidence system and power supply are of Beckman design (Sharp and Ellis, 1965).
On the boundary slip of fluid flow

This paper presents a stress controlled boundary slip model and predicts the fluid-solid interface slip in a system of parallel sliding plates or a sphere approaching a smooth plane. The numerical simulation results are in striking agreement with the existing experimental observations. This model assumes that there is a limiting shear stress. No slip occurs if the surface shear stress is smaller than the limiting shear stress, and slip occurs when the surface shear stress equals it. It is found that boundary slip dramatically decreases the hydrodynamic pressure if the two squeezed surfaces have the same slip property. Finally, the hydrodynamic force reaches a saturation status and almost does not decrease any more. Compared with the no-slip solution, hydrodynamic force is found to decrease by over two orders in the case of boundary slip. When the squeezed surfaces have different slip properties, however, the hydrodynamic pressure is mainly controlled by the surface having a smaller surface limiting shear stress, and reduces more slowly compared with the case of two surfaces having the same slip property. Even when one of the surfaces has a zero surface limiting shear stress, a considerable hydrodynamic force still exists.
Human saliva and dried saliva spots as source of DNA for PCR based HLA typing using a combination of Taq DNA polymerase and AccuPrime Taq polymerase

Genomic DNA extracted from human saliva samples showed high intra-subject variations in DNA yield compelling the need to explore a methodology for accurate quantitation of the extracted genomic DNA. Quantitative assessment of DNA extracted from saliva was achieved using human coagulation factor XIII as an internal control for subsequent downstream applications of amplification of human leucocyte antigen (HLA) genes by PCR. The PCR signals for the HLA target genes namely HLA-A, -B, -C , DPB1, DQB1 and DRB1 of exons 2 and 3 improved greatly with the use of combination of Taq DNA polymerase and AccuPrime Taq DNA polymerase. We also describe a new method of using dried saliva spots (DSS) as an alternate source of gDNA for HLA typing. PCR-based typing of DNA from human saliva offers a potential method for HLA typing and amplification and typing of DNA, thus presented, could be applied in forensic science to saliva samples recovered from the crime scenes.
Electromagnetic instabilities in an inhomogeneous plasma

General dispersion relation for a collisionless inhomogeneous plasma. Simplified dispersion relations. Inertial magneto-drift instabilities in a collisionless finite-B plasma. Alfven magneto-drift instabilities in a finite-B plasma. Low-frequency instabilities in a two-energy component plasma. Electromagnetic instabilities in a strongly inhomogeneous plasma. Description of perturbations in a plasma with transverse current. Transverse-current-drive instabilities. Hydrodynamic description of collisional finite-B plasma perturbations. Starting equations for basic types of hydrodynamic perturbations. Instabilities in a collisional finite-B plasma. Instabilities in force-free and almost force-free high-B plasmas. Electromagnetic Kelvin-Helmholtz instabilities. Electromagnetic drift instabilities in a low-B plasma. Allowance for magnetic-field curvature effects. Magnetic-field curvature effects in kinetic and two-fluid instabilities. References. Index.
Unified theory of acceptance and use of technology (UTAUT) in mobile learning adoption : Systematic literature review and bibliometric analysis

Various literature studies have been conducted to provide valuable information regarding the current research trend of Unified Technology Acceptance and Use Theory (UTAUT). When the literature was examined, it was seen that the UTAUT research on the adoption of mobile learning (M-learning) was ignored. Therefore, it was deemed necessary to conduct a literature study on the adoption of mobile learning. In this context, 31 research articles on the adoption of M-learning with UTAUT, published from 2003 to 2020, have been discussed for systematic literature research. These 31 specific research publications were discussed under four categories Performance Expectancy, Effort Expectancy, Social Influence and Facilitating Conditions. 63 different factors were identified after systematic literature review, except for UTAUT factors. These factors were grouped under 10 main factors. In addition, the authors in this field were identified by bibliometric analysis and the relationships between each other were determined by citation analysis. In addition to these, prominent terms have been determined according to the keywords and abstracts in the relevant articles. The connections between these terms have been created by the method of co-occurrence. Finally, the links between prominent terms and terms were examined with bibliometric analysis. According to the findings obtained, it has been determined that most UTAUT studies involving M-learning focus on extending UTAUT with external variables. It has been observed that the analyzed studies generally took place in the Asian countries. These studies have been carried out as multidisciplinary. In addition, it has been reported that most of these studies on M-learning take place in higher education settings. It is thought that the findings obtained at the end of the systematic literature review and bibliometric analysis study on the adoption of M-learning with UTAUT will constitute an important reference for academicians in this field.
The interplay of user beliefs and situated characteristics in explaining school performance feedback use

ABSTRACT The present study explores predictors of school performance feedback (SPF) use. In total, 470 Flemish educational professionals were surveyed about their use of SPF from school-external, low-stakes standardized assessments. A path analysis was conducted in order to investigate how individual user beliefs impact SPF use at the school level and how those beliefs mediate the effects of school-level features pertaining to school organization, performance, and voluntariness. Findings include that users’ cognitive attitude and perceived expectations of others have a small effect on engagement with SPF in schools, and that these predictors mediate the effects of certain organizational characteristics. Whereas performance levels do not impact school-level feedback use, voluntariness in feedback pursuit and particularly an SPF-oriented school culture emerge as drivers. Implications for practice include the need for stimulating ownership in data-based decision making. Suggestions for further research are also discussed.
Doubly indexed flag variety and fixed point set of a partial flag variety

We define a variety of doubly indexed flags, this is a smooth, projective variety, and we describe it as an iterated over Grassmannian varieties. On the other hand, we consider the variety of partial flags which are stabilized by a given nilpotent endomorphism. We partition this variety into locally closed subvarieties which are vector bundles over varieties of the aforedmentioned type.
A SAT Attack on Rota's Basis Conjecture

The SAT modulo Symmetries (SMS) is a recently introduced framework for dynamic symmetry breaking in SAT instances. It combines a CDCL SAT solver with an external lexicographic minimality checking algorithm. We extend SMS from graphs to matroids and use it to progress on Rota’s Basis Conjecture (1989), which states that one can always decompose a collection of r disjoint bases of a rank r matroid into r disjoint rainbow bases. Through SMS, we establish that the conjecture holds for all matroids of rank 4 and certain special cases of matroids of rank 5. Furthermore, we extend SMS with the facility to produce DRAT proofs. External tools can then be used to verify the validity of additional axioms produced by the lexicographic minimality check. As a byproduct, we have utilized our framework to enumerate matroids modulo isomorphism and to support the investigation of various other problems on matroids.
Numerical Simulation of Unsteady Flows and Transition to Turbulence

Numerical Simulation Of Unsteady Flows And Transition To . Sun, 14 Apr 2019 15:59:00 GMT [PDF]Free Numerical Simulation Of Unsteady Flows And Transition To Turbulence download Book Numerical Simulation Of Unsteady Flows And Transition To Turbulence.pdf Dmitry Kolomenskiy | JAMSTEC Academia.edu Fri, 05 Apr 2019 20:27:00 GMT Dmitry Kolomenskiy, JAMSTEC, Center for Earth Information Science and Technology, Post-Doc. Studies High . Numerical Simulation of Unsteady Flows and Transition to . Fri, 18 Mar 2016 16:48:00 GMT
Influence of coolant on ductile mode processing of binderless nanocrystalline tungsten carbide through ultraprecision diamond turning

Molds made of tungsten carbide are typically used for the replicative mass production of glass lenses by precision glass molding. Consequently an ultra-precision grinding process with a subsequent fresh-feed polishing operation is conventionally applied. These processes are time consuming and have a relatively low reproducibility. An alternative manufacturing technology, with a high predictability and efficiency, which additionally allows a higher geometrical flexibility, is the single point diamond turning technique (SPDT). However, the extreme hardness and the chemical properties of tungsten carbide lead to significant tool wear and therefore the impossibility of machining the work pieces in an economical way. One approach to enlarge the tool life is to affect the contact zone between tool and work piece by the use of special cutting fluids. This publication emphasizes on the most recent investigations and results in direct machining of nano-grained tungsten carbide with mono crystal diamonds under the influence of various kinds of cutting fluids. Therefore basic ruling experiments on binderless nano grained tungsten carbide were performed, where the tool performed a linear movement with a steadily increasing depth of cut. As the ductile cutting mechanism is a prerequisite for the optical manufacturing of tungsten carbide these experiments serve the purpose for establish the influence of different cutting fluid characteristics on the cutting performance of mono crystal diamonds. Eventually it is shown that by adjusting the coolant fluid it is possible to significantly shift the transition point from ductile to brittle removal to larger depths of cut eventually enabling a SPDT of binderless tungsten carbide molds.
Point of Interest Category Prediction with Under-Specified Hierarchical Labels

Categories are important elements of databases of Product Listings, for e-commerce platforms, or of Points of Interest (POIs), for location-based services. However, category annotations are often incomplete, which calls for automatic completion. Hierarchical classification has been proposed as a solution to impute missing annotations. We address this task in one of Naver’s production databases (POIs), in order to enhance its quality. In real-life applications, like ours, however, it is unrealistic to count on the existence of a perfectly annotated training set, and noisy training labels prevent us from casting the task as a straightforward classification problem. In order to overcome this difficulty, we propose an approach that takes into account the type of noise in the training set. We identified that the main deficiency is that the training labels tend to be under-specified i.e. they point to categories found at higher levels of the hierarchy than the correct ones. This results in a lot of under-represented and a few over-represented categories. We call categories that are over-represented, due to under-specified labels, joker classes. To allow robust learning in the presence of joker classes we propose a simple and ef- fective approach: First, we detect problematic categories, i.e. joker classes, based on the misclassifications of an initial hierarchical classifier. Then we re-train from scratch, introducing a weight to the standard cross-entropy loss function that targets incorrect predictions related to joker classes. Our model has enabled the correction of thousands of POIs in our production database.
Single-walled carbon nanotube bundles intercalated with semiconductor nanoparticles

Nanoparticles of CdSe, CdS and ZnSe have been incorporated in the inter-tubular gaps of single-walled carbon nanotube (SWNT) bundles. Electron microscope, X-ray diffraction (XRD), electronic spectroscopy and Raman studies have been employed to characterize these systems. The lengths of the intercalate inside the bundles could be varied by changing the reaction conditions. Electronic absorption and photoluminescence studies from the semiconductor intercalates show the expected blue-shift with respect to the corresponding bulk samples in CdS and ZnS samples. The SWNT lattice is expanded on incorporating CdSe as confirmed by XRD in the low-angle range. The expansion in the lattice is also corroborated by the Raman measurements which show a considerable red-shift for both the radial and the tangential modes of the SWNT signal, thus signifying an increase in the van der Waals gap between the tubes in the bundle. The red-shift of the Raman signal is due to the decrease in the inter-tube interactions as well as due to doping effects.
The maximum of a branching random walk with semiexponential increments

We consider an infinite Galton-Watson tree Γ and label the vertices υ with a collection of i.i. d. random variables (Y υ ) υ ∈ Γ . In the case where the upper tail of the distribution of Y υ is semiexponential, we then determine the speed of the corresponding tree-indexed random walk. In contrast to the classical case where the random variables Y υ have finite exponential moments, the normalization in the definition of the speed depends on the distribution of Y υ . Interpreting the random variables Y υ as displacements of the offspring from the parent, (Y υ ) υ ∈ Γ describes a branching random walk. The result on the speed gives a limit theorem for the maximum of the branching random walk, that is, for the position of the rightmost particle. In our case, this maximum grows faster than linear in time.
Projective structures on Riemann surfaces and Kleinian groups

Let S be a compact Riemann surface of genus 2, and let iv: U--->S be a holomorphic universal covering of S with the covering transformation group F , where U is the upper half plane {z e C : 1m z>0}. T h en , is a finitely generated Fuchsian group of the first kind on U and consists of hyperbolic Mobius transformations. We denote by B,(L, r) the Banach space of all holomorphic quadratic differentials for F defined on the lower half plane L . Namely, B A , F ) is the set of all holomorphic functions 0 on L satisfying