cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Further Notes on a Family of Continuous, Non-differentiable Functions
Creators: name: McCollum, Joey
Publisher: name: arXiv
Year: 2010
Subjects: subject: Dynamical Systems (math.DS)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 26A30, 37C45

description: We examine a parameterized family of functions F_a, all of which are continuous and some of which are nowhere or almost nowhere differentiable, we explore the behavior of F'_a and F"_a almost everywhere for different values of a, focusing on specific questions regarding F_a's differentiability for certain a, and we calculate the Hausdorff dimension of the graphs of all F_a.
description: 8 pages, 0 figures
Soft gluon resummation of Drell-Yan rapidity distributions: theory and phenomenology
Creators: name: Bonvini, Marco
name: Forte, Stefano
name: Ridolfi, Giovanni
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We examine critically the theoretical underpinnings and phenomenological implications of soft gluon (threshold) resummation of rapidity distributions at a hadron collider, taking Drell-Yan production at the Tevatron and the LHC as a reference test case. First, we show that in perturbative QCD soft gluon resummation is necessary whenever the partonic (rather the hadronic) center-of-mass energy is close enough to threshold, and we provide tools to assess when resummation is relevant for a given process. Then, we compare different prescriptions for handling the divergent nature of the series of resummed perturbative corrections, specifically the minimal and Borel prescriptions. We assess the intrinsic ambiguities of resummed results, both due to the asymptotic nature of their perturbative expansion, and to the treatment of subleading terms. Turning to phenomenology, we introduce a fast and accurate method for the implementation of resummation with the minimal and Borel prescriptions using an expansion on a basis of Chebyshev polynomials. We then present results for W and Z production as well as both high- and low-mass dilepton pairs at the LHC, and show that soft gluon resummation effects are generally comparable in size to NNLO corrections, but sometimes affected by substantial ambiguities.
description: 75 pages, 34 figures, pdflatex
Numerical Simulation of the Nernst Effect in Extreme Type-II Superconductors: A Negative Nernst Signal and its Noise Power Spectra
Creators: name: Chung, Sangwoo S.
name: Kakashvili, Paata
name: Bolech, C. J.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Recently, different transport coefficients have been measured in High-Tc superconductors to pinpoint the nature of the pseudogap phase. In particular, the thermoelectric coefficients received a considerable attention both theoretically and experimentally. We numerically simulate the Nernst effect in extreme type-II superconductors using the time-dependent Ginzburg-Landau equations. We report the sign reversal of the thermoelectric coefficient, alpha_xy, at temperatures close to the mean-field transition temperature, Tc^{MF}(H), which qualitatively agrees with recent experiments on high-Tc materials. We also discuss the noise power spectrum of alpha_xy, which shows 1/f^beta behavior. Based on this observation, we propose an experiment to distinguish among different regimes of vortex dynamics by measuring the noise correlations of the Nernst signal.
description: 6 pages, 6 figures
Synthesis, structure and photophysical properties of binuclear methylplatinum complexes containing cyclometalating 2-phenylpyridine or benzo{h}quinoline ligands: a comparison of intramolecular Pt–Pt and π–π interactions
Creators: name: Jamali, S.
name: Czerwieniec, Rafal
name: Kia, Reza
name: Jamshidi, Zahra
name: Zabel, Manfred
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The binuclear cyclometalated complexes [Pt2Me2(ppy)2(μ-dppm)], 1a, and [Pt2Me2(bhq)2(μ-dppm)], 1b, in which ppy = 2-phenylpyridyl, bhq = benzo{h}quinoline and dppm = bis(diphenylphosphino)methane, were synthesized by the reaction of [PtMe(SMe2)(ppy)] or [PtMe(SMe2)(bhq)] with 1/2 equiv of dppm at room temperature, respectively. Complexes 1a and 1b were fully characterized by multinuclear (1H, 31P, 13C, and 195Pt) NMR spectroscopy and were further identified by single crystal X-ray structure determination. A comparison of the intramolecular Pt–Pt and π–π interactions in complexes 1a and 1b has been made on the basis of data on crystal structures and wave functions analysis. The binuclear complexes 1a and 1b are luminescent in the solid state, and showing relatively intense orange–red emissions stemming from 3MMLCT excited states. The reaction of complex 1b with excess MeI gave the binuclear cyclometalated Pt(IV)–Pt(IV) complex [Pt2Me4(bhq)2(μ-I)2], 2. Crystal structure of complex 2 shows intermolecular C–H⋯I and C–H⋯π interactions in solid state.
Overcoming the overcoming story : critical disability studies informed geneologies of compulsory heroism
Creators: name: DeVolder, Elizabeth
Publisher: name: University of British Columbia
Year: 2017

description: The “overcomer”—the person who succeeds against all odds—has become a persistent cultural trope for persons with disability. Although it has been critiqued by the disability community for over twenty years, its employment in the media continues apace. This dissertation explores the changing and ongoing work of the overcoming narrative through a series of critical disability studies informed genealogies. Employing three analytical approaches (Genealogy as Analysis of Lines of Descent [GALD], Genealogy as Lines of Emergence [GALE], and Genealogy as Analysis of Counter-Memory [GACoM]) and three idiosyncratic styles of genealogy (Snapshot, Shifts in Historical Word Usage [SHWU], and Hotspot genealogies), I trace the course of overcoming narrative from its employment: as religious rhetoric in institutions for the blind and the deaf, as morality tales in the social reform of the Progressive Era, as propaganda in the reeducation of returning World War One soldiers, as success stories in the legitimization of rehabilitation as the third phase of medicine, and, in its most recent manifestation, as compulsory heroism in the context of the rise of the celebrity hero and large scale fundraising. I argue, extending Adrienne Rich’s compulsory heterosexuality (1994) and Rob McRuer’s compulsory able-bodiedness (2006), that, as an effect and strategy of normalization, compulsory heroism has become the only acceptable subject position made available to marginalized persons facing adversity of all kinds. Across genealogies, the wide reach of the overcoming narrative and the subject positions and subjectivities produced through three binaries become evident: the able-bodied/the-variously-other-classified, the helper/the needy, and the productive/the dependent citizen. Further, the work of overcoming narratives as tools of persuasion, devices of disavowal, techniques of depoliticization, and instruments of homogenization becomes clearer. I maintain that overcoming stories are not uniquely or even fundamentally disability stories—they are redemption stories. As such, compulsory heroism has cultural purchase in the lives of all North Americans.
Derived autoequivalences from periodic algebras
Creators: name: Grant, Joseph
Publisher: name: arXiv
Year: 2011
Subjects: subject: Representation Theory (math.RT)
subject: FOS: Mathematics
subject: 18E30, 16E35, 16D50

description: We present a construction of autoequivalences of derived categories of symmetric algebras based on projective modules with periodic endomorphism algebras. This construction generalises autoequivalences previously constructed by Rouquier-Zimmermann and is related to the autoequivalences of Seidel-Thomas and Huybrechts-Thomas. We show that compositions and inverses of these equivalences are controlled by the resolutions of our endomorphism algebra and that each autoequivalence can be obtained by certain compositions of derived equivalences between algebras which are in general not Morita equivalent.
description: 34 pages; v2 is post referee report. The biggest changes from v1 are in Section 5.2. Final version has appeared in Proc. LMS
He-atom scattering from MgO(100): calculating diffraction peak intensities with a semi ab initio potential
Creators: name: Martinez-Casado, R.
name: Mallia, G.
name: Usvyat, Denis
name: Maschio, L.
name: Casassa, S.
name: Schütz, Martin
name: Harrison, N. M.
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: An efficient model describing the He-atom scattering process is presented. The He–surface interaction potential is calculated from first principles by exploiting second-order Rayleigh–Schrödinger many-body perturbation theory and fitted by using a variety of pairwise interaction potentials. The attractive part of the fitted analytical form has been upscaled to compensate the underestimation of the well depth for this system in the perturbation theory description. The improved potential has been introduced in the close-coupling method to calculate the diffraction pattern. Quantitative agreement between the computed and observed binding energy and diffraction intensities for the He–MgO(100) system is achieved. It is expected that the utility of He scattering for probing dynamical processes at surfaces will be significantly enhanced by this quantitative description.
The basic geometry of Witt vectors, II: Spaces
Creators: name: Borger, James
Publisher: name: arXiv
Year: 2010
Subjects: subject: Algebraic Geometry (math.AG)
subject: Category Theory (math.CT)
subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 13F35, 14F30, 14F20, 18F20

description: This is an account of the algebraic geometry of Witt vectors and arithmetic jet spaces. The usual, "p-typical" Witt vectors of p-adic schemes of finite type are already reasonably well understood. The main point here is to generalize this theory in two ways. We allow not just p-typical Witt vectors but those taken with respect to any set of primes in any ring of integers in any global field, for example. This includes the "big" Witt vectors. We also allow not just p-adic schemes of finite type but arbitrary algebraic spaces over the ring of integers in the global field. We give similar generalizations of Buium's formal arithmetic jet functor, which is dual to the Witt functor. We also give concrete geometric descriptions of Witt spaces and arithmetic jet spaces and investigate whether a number of standard geometric properties are preserved by these functors.
description: Final version
Glycomics meets lipidomics - associations of N-glycans with classical lipids, glycerophospholipids, and sphingolipids in three European populations
Creators: name: Igl, Wilmar
name: Polasek, Ozren
name: Gornik, Olga
name: Knežević, Ana
name: Pučić, Maja
name: Novokmet, Mislav
name: Huffman, Jenifer
name: Gnewuch, Carsten
name: Liebisch, Gerhard
name: Schmitz, Gerd
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie
subject: 610 Medizin

description: Recently, high-throughput technologies have been made available which allow the measurement of a broad spectrum of glycomics and lipidomics parameters in many samples. The aim of this study was to apply these methods and investigate associations between 46 glycan and 183 lipid traits measured in blood of 2041 Europeans from three different local populations (Croatia - VIS cohort; Sweden - NSPHS cohort; Great Britain - ORCADES cohort). N-glycans have been analyzed with High Performance Liquid Chromatography (HPLC) and lipids with Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS) covering sterol lipids, glycerolipids, glycerophospholipids and sphingolipids in eight subclasses. Overall, 8418 associations were calculated using linear mixed effect models adjusted for pedigree, sex, age and multiple testing. We found 330 significant correlations in VIS. Pearson's correlation coefficient r ranged from −0.27 to 0.34 with corresponding p-values between 1.45 × 10−19 and 4.83 × 10−6, indicating statistical significance. A total of 71 correlations in VIS could be replicated in NSPHS (r = [−0.19; 0.35], p = [4.16 × 10−18; 9.38 × 10−5]) and 31 correlations in VIS were also found in ORCADES (r = [−0.20; 0.24], p = [2.69 × 10−10; 7.55 × 10−5]). However, in total only 10 correlations between a subset of triantennary glycans and unsaturated phosphatidylcholine, saturated ceramide, and sphingomyelin lipids in VIS (r = [0.18; 0.34], p = [2.98 × 10−21; 1.69 × 10−06]) could be replicated in both NSPHS and ORCADES. In summary, the results show strong and consistent associations between certain glycans and lipids in all populations, but also population-specific correlations which may be caused by environmental and genetic differences. These associations point towards potential interactive metabolic pathways.
Representations of task assignments in distributed systems using Young tableaux and symmetric groups
Creators: name: Kim, Dohan
Publisher: name: arXiv
Year: 2010
Subjects: subject: Distributed, Parallel, and Cluster Computing (cs.DC)
subject: Group Theory (math.GR)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: This paper presents a novel approach to representing task assignments for partitioned agents (respectively, tasks) in distributed systems. A partition of agents (respectively, tasks) is represented by a Young tableau, which is one of the main tools in studying symmetric groups and combinatorics. In this paper we propose a task, agent, and assignment tableau in order to represent a task assignment for partitioned agents (respectively, tasks) in a distributed system. This paper is concerned with representations of task assignments rather than finding approximate or near optimal solutions for task assignments. A Young tableau approach allows us to raise the expressiveness of partitioned agents (respectively, tasks) and their task assignments.
description: This is an Accepted Manuscript of an article published by Taylor & Francis Group in International Journal of Parallel, Emergent and Distributed Systems on 02/02/2015, available online: http://dx.doi.org/10.1080/17445760.2014.997729
Lipschitz retraction and distortion for subgroups of Out(F_n)
Creators: name: Handel, Michael
name: Mosher, Lee
Publisher: name: arXiv
Year: 2010
Subjects: subject: Group Theory (math.GR)
subject: Geometric Topology (math.GT)
subject: FOS: Mathematics
subject: 20F65 (Primary) 57M07 (Secondary)

description: Given a free factor A of the rank n free group F_n, we characterize when the subgroup of Out(F_n) that stabilizes the conjugacy class of A is distorted in Out(F_n). We also prove that the image of the natural embedding of Aut(F_{n-1}) in Aut(F_n) is nondistorted, that the stabilizer in Out(F_n) of the conjugacy class of any free splitting of F_n is nondistorted, and we characterize when the stabilizer of the conjugacy class of an arbitrary free factor system of F_n is distorted. In all proofs of nondistortion, we prove the stronger statement that the subgroup in question is a Lipschitz retract. As applications we determine Dehn functions and automaticity for Out(F_n) and Aut(F_n).
description: Version 3: 35 pages. Revised for publication. Changes from previous versions: significant economies in exposition. Added an explicit description of the stabilizer of a free splitting, in Lemma 18
Benzotriazolate cage complexes of tin(II) and lithium: halide-influenced serendipitous assembly
Creators: name: Bodensteiner, Michael
name: Scheuermeyer, Sabine
name: Scheer, Manfred
name: Zabel, Manfred
name: Sulway, Scott A.
name: Layfield, Richard A.
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The one-pot reactions of the tin(II) halides SnX2 (X = F, Cl, Br, I) with lithium hexamethyldisilazide, [Li(hmds)], and benzotriazole, (bta)H, produce contrasting outcomes. Tin(II) fluoride does not react with [Li(hmds)] and (bta)H, the outcome being the formation of insoluble [Li(bta)]∞. Tin(II) chloride and tin(II) bromide react with [Li(hmds)] and (bta)H in toluene to produce the hexadecametallic tin(II)-lithium cages [(hmds)8Sn8(bta)12Li8X4]·(ntoluene) [X = Cl, 3·(8 toluene); X = Br, 4·(3 toluene)]. The reaction of tin(II) iodide with [Li(hmds)] and (bta)H in thf solvent produces the ion-separated species [{(thf)2Li(bta)}3{Li(thf)}]2[SnI4]·(thf), [5]2[SnI4]·(thf), the structure of which contains a cyclic trimeric unit of lithium benzotriazolate and a rare example of the tetraiodostannate(II) dianion.
Polarization charge densities provide a predictive quantification of hydrogen bond energies
Creators: name: Klamt, Andreas
name: Reinisch, Jens
name: Eckert, Frank
name: Hellweg, Arnim
name: Diedenhofen, Michael
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: A systematic density functional theory based study of hydrogen bond energies of 2465 single hydrogen bonds has been performed. In order to be closer to liquid phase conditions, different from the usual reference state of individual donor and acceptor molecules in vacuum, the reference state of donors and acceptors embedded in a perfect conductor as simulated by the COSMO solvation model has been used for the calculation of the hydrogen bond energies. The relationship between vacuum and conductor reference hydrogen bond energies is investigated and interpreted in the light of different physical contributions, such as electrostatic energy and dispersion. A very good correlation of the DFT/COSMO hydrogen bond energies with conductor polarization charge densities of separated donor and acceptor atoms was found. This provides a method to predict hydrogen bond strength in solution with a root mean square error of 0.36 kcal mol−1 relative to the quantum chemical dimer calculations. The observed correlation is broadly applicable and allows for a predictive quantification of hydrogen bonding, which can be of great value in many areas of computational, medicinal and physical chemistry.
Control of metal-directed self-assembly by metal–amine interactions
Creators: name: Katayev, E.
name: Schmid, Markus B.
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The complexation of a tweezers ligand with zinc perchlorate in the absence and presence of amines in methanol solution was explored. L2Zn2(ClO4)4 was a thermodynamic product of the reaction in the absence of an amine. The complex was shown to interact with aliphatic amines resulting in the formation of a Zn–N(amine) bond. If metal–ligand complexation was carried out in the presence of an amine the formation of a trinuclear zinc complex L3Zn36+ was observed. Moreover the transformation of complex L2Zn24+ to L3Zn36+ occurred, when the former was subjected to an amine in the amount, which is sufficient to coordinate more than one amino group on each zinc atom. Complexes ligand-zinc-amine were shown to be kinetically stable, and the method of their preparation was crucial to the purity of the final complexes. L3Zn36+ was favored under kinetic control: reagent concentration 10−5M, slow addition of zinc perchlorate to the mixture of an amine and the ligand. Under thermodynamic control (fast mixing of reagents, concentration 10−2–10−3 M) formation of a mixture of complexes was observed. All pure complexes and their mixtures were characterized using UV-Vis, ROESY, PFGSE NMR and ESI-MS techniques. On the basis of DFT calculations the mechanism of influence of an amine on self-assembly was suggested.
Tight conditions for consistency of variable selection in the context of high dimensionality
Creators: name: Comminges, Laëtitia
name: Dalalyan, Arnak
Publisher: name: arXiv
Year: 2011
Subjects: subject: Statistics Theory (math.ST)
subject: FOS: Mathematics
subject: 62G08 (Primary) 62H12, 62H15 (Secondary)

description: We address the issue of variable selection in the regression model with very high ambient dimension, that is, when the number of variables is very large. The main focus is on the situation where the number of relevant variables, called intrinsic dimension, is much smaller than the ambient dimension d. Without assuming any parametric form of the underlying regression function, we get tight conditions making it possible to consistently estimate the set of relevant variables. These conditions relate the intrinsic dimension to the ambient dimension and to the sample size. The procedure that is provably consistent under these tight conditions is based on comparing quadratic functionals of the empirical Fourier coefficients with appropriately chosen threshold values. The asymptotic analysis reveals the presence of two quite different re gimes. The first regime is when the intrinsic dimension is fixed. In this case the situation in nonparametric regression is the same as in linear regression, that is, consistent variable selection is possible if and only if log d is small compared to the sample size n. The picture is different in the second regime, that is, when the number of relevant variables denoted by s tends to infinity as $n\to\infty$. Then we prove that consistent variable selection in nonparametric set-up is possible only if s+loglog d is small compared to log n. We apply these results to derive minimax separation rates for the problem of variable
description: arXiv admin note: text overlap with arXiv:1102.3616; Published in at http://dx.doi.org/10.1214/12-AOS1046 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org)
Structure and bonding in three-coordinate N-heterocyclic carbene adducts of iron(II) bis(trimethylsilyl)amide
Creators: name: Layfield, Richard A.
name: McDouall, J.
name: Scheer, Manfred
name: Schwarzmaier, Christoph
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The molecular structures, chemical bonding and magnetochemistry of the three-coordinate iron(II) NHC complexes [(NHC)Fe{N(SiMe3)2}2] (NHC = IPr, 2; NHC = IMes, 3) are reported.
Periodic ab initio estimates of the dispersive interaction between molecular nitrogen and a monolayer of hexagonal BN
Creators: name: Halo, M.
name: Casassa, S.
name: Maschio, L.
name: Pisani, C.
name: Dovesi, R.
name: Ehinon, D.
name: Baraille, I.
name: Rerat, M.
name: Usvyat, Denis
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The ab initio determination of the leading long-range term of pairwise additive dispersive interactions, based on the independent analysis of the response properties of the interacting objects, is here considered in the case where these are part of a periodic system. The interaction of a nitrogen molecule with a thin film of hexagonal BN has been chosen as a case study for identifying some of the problems involved, and for proposing techniques for their solution. In order to validate the results so obtained, the interaction energy between N2 and a BN monolayer at different distances has been estimated following a totally different approach, namely by performing post-Hartree–Fock (MP2) supercell calculations using the CRYSTAL+CRYSCOR suite of programs. The results obtained with the two approaches closely agree over a long range, while the limit of validity of the purely dispersive regime can be clearly assessed.
Scaffolds for Dental Pulp Tissue Engineering
Creators: name: Galler, Kerstin M.
name: D’Souza, R. N.
name: Hartgerink, J. D.
name: Schmalz, G.
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: scaffolds, dental tissue engineering, dental stem cells, hydrogel, selfassembling peptides, regenerative medicine
subject: 610 Medizin

description: For tissue engineering strategies, the choice of an appropriate scaffold is the first and certainly a crucial step. A vast variety of biomaterials is available: natural or synthetic polymers, extracellular matrix, self-assembling systems, hydrogels, or bioceramics. Each material offers a unique chemistry, composition and structure, degradation profile, and possibility for modification. The role of the scaffold has changed from passive carrier toward a bioactive matrix, which can induce a desired cellular behavior. Tailor-made materials for specific applications can be created. Recent approaches to generate dental pulp rely on established materials, such as collagen, polyester, chitosan, or hydroxyapatite. Results after transplantation show soft connective tissue formation and newly generated dentin. For dentinpulp- complex engineering, aspects including vascularization, cell-matrix interactions, growth-factor incorporation, matrix degradation, mineralization, and contamination control should be considered. Self-assembling peptide hydrogels are an example of a smart material that can be modified to create customized matrices. Rational design of the peptide sequence allows for control of material stiffness, induction of mineral nucleation, or introduction of antibacterial activity. Cellular responses can be evoked by the incorporation of cell adhesion motifs, enzymecleavable sites, and suitable growth factors. The combination of inductive scaffold materials with stem cells might optimize the approaches for dentin-pulp complex regeneration.
Paths to sustainability : creating connections through place-based Indigenous knowledge
Creators: name: Brauer, Celia
Publisher: name: University of British Columbia
Year: 2017

description: For most of humanity’s existence, a robust human-nature relationship was paramount. Any inherent benefits were clearly understood and respected. However, in the last 500 years of western history, religious dependence diminished in favour of a more rational and humanist approach and market economics rose in prominence. This evolution encouraged notions of cultural separation from nature that led to an emphasis on the individual, the expansion of private land ownership and the commodification of natural resources. These misguided beliefs then spread throughout the world during colonization. The result has been a mass degradation of the earth’s ecological health, alongside a strong decrease in the positive qualities of tradition and community life. Repair of the human-nature connection is urgent. This research demonstrates that Indigenous people living among us today who embody Traditional Ecological Knowledge (TEK) can offer insights to heal this serious rift. They teach us that without honest human-nature relationships and a grounded existence in place, long-term prosperity for western civilization will be challenging. An Indigenous worldview demonstrates that place-based learning and the repair of community connections is imperative for healthy social-ecological systems. Nature’s importance must be regarded for its own sake, not just for the benefit of humans. Incorporating these principles into present-day society encourages more sustainable practices and helps to treat our common planet with respect. In addition, the act of receiving traditional wisdom from our Indigenous neighbours facilitates a reconciliation of the tragic legacies that endure from colonization. Without this fundamental healing, little long-term recovery of people and the land is likely.
Stereoselective routes to aryl substituted γ-butyrolactones and their application towards the synthesis of highly oxidised furanocembranoids
Creators: name: Macabeo, Allan Patrick
name: Kreuzer, Andreas
name: Reiser, Oliver
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: Titanium chelate addition of aryl nucleophiles to cyclopropyl aldehyde 6 followed by a tin-catalyzed one-pot retro-aldol, acetalisation and lactonisation sequence afforded cis and trans γ-aryllactone acetals. A γ-furyllactone derived by this approach was further transformed in two steps to model compounds for the oxidised northeastern sectors of selected Pseudopterogorgia diterpenoids.
Eye gaze tracking in surgical robotics
Creators: name: Tong, Irene Go
Publisher: name: University of British Columbia
Year: 2017

description: Robot-assisted surgery allows surgeons to have improved control and visualization in minimally invasive procedures. Eye gaze tracking is a valuable tool for studying and improving the surgeon experience during robot-assisted surgery. Eye gaze information gives insight on how surgeons are interacting with surgical systems as well as their intentions during surgical tasks. This thesis describes the development of an eye gaze tracker for the da Vinci Surgical System. The eye gaze tracker is designed to track both the 2D and 3D eye gaze of a surgeon. It interfaces with the da Vinci Surgical System through the da Vinci Research Kit (dVRK) and Robot Operating System (ROS) frameworks. The use of the eye gaze tracker is demonstrated in two applications. Firstly, a motor control framework is designed to aid surgeons in moving surgical tools towards their point of gaze. A haptic force is applied to the da Vinci master manipulators to pull the surgeon's hands towards where they are looking. This framework is demonstrated on a full da Vinci Surgical System on dry lab tasks. Secondly, eye gaze information is collected from 7 surgeons performing realistic clinical tasks with the da Vinci Surgical System. A prediction model using a random forest classifier is built based on the eye gaze information and tool kinematic information in order to predict how and when surgeons move their camera. This behavioural model has applications in both surgeon training and endoscope automation.
Producing silicon carbide boron carbide composites by spark plasma sintering
Creators: name: Aygüzer Yaşar, Zeynep
Publisher: name: No Publisher Supplied
Year: 2019

description: Silicon carbide has a high melting point, high mechanical and elastic properties and excellent chemical stability. Boron carbide is a non-metallic material with exceptional physical and chemical properties. Boron carbide is third hardest material after diamond and cubic boron nitride. Besides a high hardness, boron carbide also has a high melting point, high strength, high neutron cross-section, and low density. Due to the their outstanding properties both materials can be used in spray nozzles, turbine engines, heat conducting tubes, and in the defense industry as armor plates.  Since silicon carbide and boron carbide are both strongly covalent bonded, the densification of these materials is extremely difficult. High sintering temperature and fine powder sizes are critical to achieve a high density. Fine starting powders also add the presence of oxygen. The residual oxide layer forms as SiO2 on the SiC surfaces and as B2O3 on the B4C surfaces. These oxide layers inhibit high density and cause grain coarsening. The goals of this thesis were to produce high density SiC-B4C composites, optimize the mechanical properties of SiC-B4C composites, and understand the role of excess oxygen content on sinterability. To achieve these goals, the oxygen content was managed using two methods; a safe and effective laboratory scale acid etching process developed to reduce the oxygen content of SiC and additional carbon used to remove the residual oxide layer.  Then, SiC- B4C composites with varying amounts of C powders were mixed and sintered by spark plasma sintering method (SPS). The dense composites were characterized to evaluate the effect of the oxygen content and residual carbon on the microstructure and mechanical properties. The composite samples’ microstructure was characterized using The Zeiss Sigma emission scanning electron microscopy. The phase of the composites was determined using X-ray diffraction. Poisson’s ratio, Young’s modulus, shear modulus, and bulk modulus were measured by ultrasound analyses. Since the densification of a ceramic affects the mechanical properties, the Archimedes method was used to determine the density of the sintered composite samples.  Polished samples were used for hardness testing using a Vickers diamond tipped (9.8 N load) LECO-M-400-G3 and Berkovich nano-hardness (100 mN-500 mN load). The results showed that the oxygen content and the addition of carbon should be matched to achieve high density and high mechanical properties. Carbon also played a role on the mechanical properties as well as the oxygen since modifying the oxygen content by adding varying amounts of carbon caused surplus carbon. The presence of excess carbon decreased the elastic modulus and hardness of the composite.
title: TRENDS IN THE DEVELOPMENT OF COMMERCIAL MEDICINE DURING  THE PERIOD OF CORONAVIRUS INFECTION
Creators: name: Gukova, Ekaterina О.
name: Kosinova, Natal'ya N.
Publisher: name: Astrakhan State Medical University
Year: 2021

description: Abstract. The current year has made certain adjustments to the private medicine market due to the COVID-19 pandemic, as a result of which the priority areas of development of previous years may undergo changes. Various support measures were implemented both from the state and from large business and the banking sector, but how this will affect the market as a whole – time will tell. Despite low incomes and constant price increases, the Russian medical market, having gone through a stage of stagnation in 2014-2015, still continues to develop. The introduction of quarantine has made some adjustments to the situation, but no one is immune from diseases. People postponed non-urgent procedures for a while and began to visit private clinics more often.Medical care is an essential service. Even with extremely low purchasing power, a person will not refuse to see a doctor in case of injury, pain, physical pathology, or expectation of a child. Any family will prefer to save on education, entertainment, recreation, but not on the most expensive - health. There fore, medicine will always be in demand, and only its development trends change over time. Key words: COVID-19, healthcare, trends, commercial medicine, digital technologies.
Deformations of circle-valued Morse functions on surfaces
Creators: name: Maksymenko, Sergiy
Publisher: name: arXiv
Year: 2010
Subjects: subject: Geometric Topology (math.GT)
subject: Algebraic Topology (math.AT)
subject: FOS: Mathematics
subject: 37C05, 57S05, 57R45

description: Let $M$ be a smooth connected orientable compact surface. Denote by $F(M,S^1)$ the space of all Morse functions $f:M\to S^1$ having no critical points on the boundary of $M$ and such that for every boundary component $V$ of $M$ the restriction $f|_{V}:V\to S^1$ is either a constant map or a covering map. Endow $F(M,S^1)$ with the $C^{\infty}$-topology. In this note the connected components of $F(M,S^1)$ are classified. This result extends the results of S. V. Matveev, V. V. Sharko, and the author for the case of Morse functions being locally constant on the boundary of $M$.
description: 8 pages, 4 figures
Stereoselective rearrangement of guaianolides to tricyclic δ-valerolactones
Creators: name: Schanderl, Martin
name: Schwarz, Michael
name: Jeong, Won Boo
name: Reiser, Oliver
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: An unprecedented, highly stereoselective rearrangement of guaianolides, bearing a double bond at the C-6/C-6a position, to tricyclic δ-valerolactones is described.
The dynamics of financial stability in complex networks
Creators: name: da Cruz, João P.
name: Lind, Pedro G.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Risk Management (q-fin.RM)
subject: FOS: Economics and business

description: We address the problem of banking system resilience by applying off-equilibrium statistical physics to a system of particles, representing the economic agents, modelled according to the theoretical foundation of the current banking regulation, the so called Merton-Vasicek model. Economic agents are attracted to each other to exchange `economic energy', forming a network of trades. When the capital level of one economic agent drops below a minimum, the economic agent becomes insolvent. The insolvency of one single economic agent affects the economic energy of all its neighbours which thus become susceptible to insolvency, being able to trigger a chain of insolvencies (avalanche). We show that the distribution of avalanche sizes follows a power-law whose exponent depends on the minimum capital level. Furthermore, we present evidence that under an increase in the minimum capital level, large crashes will be avoided only if one assumes that agents will accept a drop in business levels, while keeping their trading attitudes and policies unchanged. The alternative assumption, that agents will try to restore their business levels, may lead to the unexpected consequence that large crises occur with higher probability.
Girsanov's formula for G-Brownian motion
Creators: name: Osuka, Emi
Publisher: name: arXiv
Year: 2011
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics

description: In this paper, we establish Girsanov's formula for $G$-Brownian motion. Peng (2007, 2008) constructed $G$-Brownian motion on the space of continuous paths under a sublinear expectation called $G$-expectation; as obtained by Denis et al. (2011), $G$-expectation is represented as the supremum of linear expectations with respect to martingale measures of a certain class. Our argument is based on this representation with an enlargement of the associated class of martingale measures, and on Girsanov's formula for martingales in the classical stochastic analysis. The methodology differs from that of Xu et al. (2011), and applies to the multi-dimensional $G$-Brownian motion.
Characterization of maize producing households in Machakos and Makueni districts in Kenya
Creators: name: Lutta  Muhammad
name:  Domisiano  Mwabu
name: Mulwa, Richard
name: Mwangi, Wilfred
name: Langyintuo, Augustine
name: Rovere, Roberto La
Publisher: name: Gates Open Research
Year: 2019

description: Characterization of maize producing households in Machakos and Makueni districts in Kenya
Toll-like Receptors, LPS, and Dental Monomers
Creators: name: Schmalz, G.
name: Krifka, Stephanie
name: Schweikl, Helmut
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: resin monomer, innate immune system, stress response, MAPK, TEGMA, HEMA
subject: 610 Medizin

description: Unreacted monomers released from dental resin-based composites at non-cytotoxic concentrations cause a depletion of glutathione and an increase of reactive oxygen species (ROS), leading to, e.g., DNA damage and apoptosis. ROS-sensitive MAP-kinases are activated by HEMA and TEGDMA. MAP-kinases are also involved in the bacteria-triggered cell responses of the innate immune system, e.g., after bacterial lipopolysaccharide (LPS) binding to the Toll-like receptor (TLR) 4. Therefore, both bacteria and monomers imply environmental stress to pulp tissue, and they may influence the target cell reactions in a combined way. In macrophages, cell-surface antigens and cytokines were up-regulated after exposure to LPS, but TEGDMA caused a significant downregulation. Regulation was dependent on exposure time, indicating that LPS and TEGDMA act differently on MAP-kinases. Furthermore, the cell type played a decisive role. Inhibition of the immune response may result in a decrease in inflammatory symptoms and/or a reduced defense capacity against bacteria.
The probability of long cycles in interchange processes
Creators: name: Alon, Gil
name: Kozma, Gady
Publisher: name: arXiv
Year: 2010
Subjects: subject: Probability (math.PR)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: We examine the number of cycles of length k in a permutation, as a function on the symmetric group. We write it explicitly as a combination of characters of irreducible representations. This allows to study formation of long cycles in the interchange process, including a precise formula for the probability that the permutation is one long cycle at a given time t, and estimates for the cases of shorter cycles.
description: 14 pages, 3rd version adds more detailed description of Toth's conjecture
Germanium/phosphorus cage compounds with germanium in three different oxidation states
Creators: name: Almstätter, Stefan
name: Balazs, Gabor
name: Bodensteiner, Michael
name: Scheer, Manfred
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: Novel germanium/phosphorus cage compounds with new structural motifs have been synthesized containing germanium in three different oxidation states. The key to obtain this new class of compounds is the use of monolithiated primary phosphine LiHPtBu in the reaction with GeX2.
Equity Assessment for Transboundary Water Resources Management Using Remote Sensing Data and QGIS
Creators: name: Dehati, Suzan
Publisher: name: Zenodo
Year: 2023
Subjects: Transboundary water management
Remote Sensing
Equity Assessment
Geospatial analysis
Water governance

description: This study aims to develop a conceptual framework to assess and quantify equity using open access remote sensing hydrological data and QGIS for the transboundary water resources of the Nile basin. Transboundary water management is a complex issue that requires a multi-faceted approach to ensure equitable distribution of water resources. The shortage of materials and methods to assess equity to help riparian countries establish operational arrangements for transboundary water management made it difficult to understand the demand and use of water in the basin, and thus created conflicts. By analyzing satellite imagery and other data sources, QGIS can help to identify areas where water resources are scarce and where demand for water may be exceeding supply. The results of this study can be used to develop policies and promote cooperation and more equitable water management practices.
Aqueous phase behaviour of choline carboxylate surfactants—exceptional variety and extent of cubic phases
Creators: name: Klein, Regina
name: Tiddy, Gordon J. T.
name: Maurer, Eva
name: Touraud, Didier
name: Esquena, Jordi
name: Tache, Olivier
name: Kunz, Werner
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: Choline carboxylate surfactants are powerful alternatives to the well-known classical alkali soaps, since they exhibit substantially increased water solubility while maintaining biocompatibility, in contrast to simple quaternary ammonium ions. In the present study, we report the aqueous binary phase diagrams and a detailed investigation of the lyotropic liquid crystalline phases formed by choline carboxylate surfactants (ChCm) with chain lengths ranging from m = 12–18 and at surfactant concentrations of up to 95–98 wt%. The identification of the lyotropic mesophases and their sequence was achieved by the penetration scan technique. Structural details are elucidated by small-angle X-ray scattering (SAXS). The general sequence of mesophases with increasing soap concentration was found to be as follows: micellar (L1), discontinuous cubic (I1), hexagonal (H1), bicontinuous cubic (V1) and lamellar (Lα). The main difference to the phase behavior of alkali soaps or of other mono-anionic surfactants is the appearance and large extent of a discontinuous cubic phase with two or even more different symmetries. The obtained phase diagrams further highlight the extraordinarily high water solubility of ChCm soaps. Finally, structural parameters of ChCm salts such as the cross-sectional area at the polar–nonpolar interface are compared to those of alkali soaps and discussed in the terms of specific counterion binding and packing constraints.
Equivalent forms of Dirac equations in curved spacetimes and generalized de Broglie relations
Creators: name: Arminjon, Mayeul
name: Reifler, Frank
Publisher: name: arXiv
Year: 2011
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: One may ask whether the relations between energy and frequency and between momentum and wave vector, introduced for matter waves by de Broglie, are rigorously valid in the presence of gravity. In this paper, we show this to be true for Dirac equations in a background of gravitational and electromagnetic fields. We first transform any Dirac equation into an equivalent canonical form, sometimes used in particular cases to solve Dirac equations in a curved spacetime. This canonical form is needed to apply the Whitham Lagrangian method. The latter method, unlike the WKB method, places no restriction on the magnitude of Planck's constant to obtain wave packets, and furthermore preserves the symmetries of the Dirac Lagrangian. We show using canonical Dirac fields in a curved spacetime, that the probability current has a Gordon decomposition into a convection current and a spin current, and that the spin current vanishes in the Whitham approximation, which explains the negligible effect of spin on wave packet solutions, independent of the size of Planck's constant. We further discuss the classical-quantum correspondence in a curved spacetime based on both Lagrangian and Hamiltonian formulations of the Whitham equations. We show that the generalized de Broglie relations in a curved spacetime are a direct consequence of Whitham's Lagrangian method, and not just a physical hypothesis as introduced by Einstein and de Broglie, and by many quantum mechanics textbooks.
description: PDF, 32 pages in referee format. Added significant material on canonical forms of Dirac equations. Simplified Theorem 1 for normal Dirac equations. Added section on Gordon decomposition of the probability current. Encapsulated main results in the statement of Theorem 2
Cut-off grade optimization of open pit mines with multiple processing streams
Creators: name: Pettingell, Michael Nash
Publisher: name: University of British Columbia
Year: 2017

description: In this study, dynamic cut-off grades and multiple processing streams are used to maximize the value of a mining project based on a finite resource. Optimal cut-off policies are generated using Lane’s method for determining cut-off grade. By maximizing the present value of future profits as a function of cut-off grade, mine project value is increased over the traditional break-even approach. A method for determining multiple cut-off grades at a single deposit was applied to analyze the impact that changes in processing capacity have on NPV. It was found that additional capacity related to a separate mill facility resulted in an economic reclassification of ore and waste. Grade tonnage data used in the case study was simulated to represent the geologic uncertainty associated to low-grade mineral deposits. Results from the hypothetical case study examined in this thesis reveal that a low-grade open pit gold mine will benefit from the use of multiple processing streams when a dynamic cut-off policy is applied. Particularly, when incorporating a “high grade” modular processing stream to maximize the potential revenue of the mineralized material. This means that for a given set of design, production and geological parameters, the classification of ore and waste is what ultimately determines the NPV of a mining project.