cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Lévy-driven polling systems and continuous-state branching processes
Creators: name: Boxma, Onno
name: Ivanovs, Jevgenijs
name: Kosiński, Kamil Marcin
name: Mandjes, Michel
Publisher: name: arXiv
Year: 2010
Subjects: subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60K25 (Primary), 90B22 (Secondary)

description: In this paper we consider a ring of $N\ge 1$ queues served by a single server in a cyclic order. After having served a queue (according to a service discipline that may vary from queue to queue), there is a switch-over period and then the server serves the next queue and so forth. This model is known in the literature as a \textit{polling model}. Each of the queues is fed by a non-decreasing Lévy process, which can be different during each of the consecutive periods within the server's cycle. The $N$-dimensional Lévy processes obtained in this fashion are described by their (joint) Laplace exponent, thus allowing for non-independent input streams. For such a system we derive the steady-state distribution of the joint workload at embedded epochs, i.e. polling and switching instants. Using the Kella-Whitt martingale, we also derive the steady-state distribution at an arbitrary epoch. Our analysis heavily relies on establishing a link between fluid (Lévy input) polling systems and multi-type Jiřina processes (continuous-state discrete-time branching processes). This is done by properly defining the notion of the \textit{branching property} for a discipline, which can be traced back to Fuhrmann and Resing. This definition is broad enough to contain the most important service disciplines, like exhaustive and gated.
Fine-tuning the balance between crystallization and gelation and enhancement of CO2 uptake on functionalized calcium based MOFs and metallogels
Creators: name: Mallick, Arijit
name: Schön, Eva-Maria
name: Panda, T.
name: Sreenivas, K.
name: Diaz Diaz, David
name: Banerjee, R.
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: The synthesis, structure, gas adsorption and catalytic properties of a new 3D porous, crystalline metal–organic framework (Ca-5TIA-MOF) as well as stable viscoelastic metallogels (Ca-5TIA-Gel) are reported. Remarkably, the preparation of both types of materials can be carried out starting from the same organic ligand (i.e. 5-(1,2,4-triazoleyl)isophthalic acid (5TIA)), divalent metal ion (i.e. Ca(II)) and organic solvent (i.e. DMF). In this particular case, the presence of water in the solvent system favors the formation of a crystalline MOF, whereas a pure organic solvent induces gelation. The characterization of the materials was carried out using a series of techniques including XRD, FT-IR, TGA, TEM, SEM, SAXS and dynamic rheology. Experimental PXRD peaks of both Ca-5TIA-xerogel and Ca-5TIA-MOF matched reasonably well with simulated PXRD, suggesting the presence of, at least, some common structural elements in the 3D networks of both xerogel and crystalline phases. Moreover, the nature of the metal counteranion was found to have a critical influence on the gelation phenomenon. To the best of our knowledge, this report describes unprecedented Ca-based LMW-metallogels, as well as the first porous Ca-based MOF, which shows adsorption capacity for CO2 at 1 atm pressure. Interestingly, Ca-5TIA-xerogel presented 20% higher CO2-uptake than the crystalline Ca-5TIA-MOF at 1 atm and 298 K. Both Ca-5TIA-MOF and Ca-5TIA-Gel also displayed a modest catalytic activity towards the hydrosilylation of benzaldehyde, with slightly better performance for the gel phase material.
Critical assessment of the efficiency of chitosan biohydrogel beads as recyclable and heterogeneous organocatalyst for C–C bond formation
Creators: name: Kühbeck, Dennis
name: Saidulu, G.
name: Rajender Reddy, K.
name: Diaz Diaz, David
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: The effectiveness of neutral pH chitosan hydrogel beads (CSHB) as a green organocatalyst for a variety of C–C bond forming reactions (i.e. aldol reaction, Knoevenagel condensation, nitroaldol (Henry) reaction, Michael addition) has been comprehensively evaluated. Reaction rates, conversions and selectivities were studied as a function of a series of input variables including size, pH and reactive surface area of the beads, catalyst loading, temperature, molecular weight of the biopolymer, concentration, solvent system and molar ratio of reactants. Moreover, the catalytic biohydrogel beads were characterized by a variety of techniques including, among others, SEM, FT-IR, TGA and DSC.
New invariants for entangled states
Creators: name: Buniy, Roman V.
name: Kephart, Thomas W.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Quantum Physics (quant-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We propose new algebraic invariants that distinguish and classify entangled states. Considering qubits as well as higher spin systems, we obtained complete entanglement classifications for cases that were either unsolved or only conjectured in the literature.
description: published version
A semi-joint neural model for sentence level discourse parsing and sentiment analysis
Creators: name: Nejat, Bita
Publisher: name: University of British Columbia
Year: 2017

description: Discourse Parsing and Sentiment Analysis are two fundamental tasks in Natural Language Processing that have been shown to be mutually beneficial. In this work, we design and compare two Neural Based models for jointly learning both tasks. In the proposed approach, we first create a vector representation for all the segments in the input sentence. Next, we apply three different Recursive Neural Net models: one for discourse structure prediction, one for discourse relation prediction and one for sentiment analysis. Finally, we combine these Neural Nets in two different joint models: Multi-tasking and Pre-training. Our results on two standard corpora indicate that both methods result in improvements in each task but Multi-tasking has a bigger impact than Pre-training.
NHC-catalysed aerobic aldehyde-esterifications with alcohols: no additives or cocatalysts required
Creators: name: Delany, E. G.
name: Fagan, C.-L.
name: Gundala, S.
name: Mari, A.
name: Broja, Thomas
name: Zeitler, Kirsten
name: Connon, S. J.
Publisher: name: Universität Regensburg
Year: 2013
Subjects: subject: 540 Chemie

description: A highly efficient, broad scope, additive-free mild protocol for the oxidative carbene-catalysed esterification of aldehydes (including the related aqueous oxidation to acids) has been developed.
Type classes for efficient exact real arithmetic in Coq
Creators: name: Krebbers, Robbert
name: Spitters, Bas
Publisher: name: arXiv
Year: 2011
Subjects: subject: Logic in Computer Science (cs.LO)
subject: Numerical Analysis (math.NA)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics
subject: D.2.4; F.4.1; G.1

description: Floating point operations are fast, but require continuous effort on the part of the user in order to ensure that the results are correct. This burden can be shifted away from the user by providing a library of exact analysis in which the computer handles the error estimates. Previously, we [Krebbers/Spitters 2011] provided a fast implementation of the exact real numbers in the Coq proof assistant. Our implementation improved on an earlier implementation by O'Connor by using type classes to describe an abstract specification of the underlying dense set from which the real numbers are built. In particular, we used dyadic rationals built from Coq's machine integers to obtain a 100 times speed up of the basic operations already. This article is a substantially expanded version of [Krebbers/Spitters 2011] in which the implementation is extended in the various ways. First, we implement and verify the sine and cosine function. Secondly, we create an additional implementation of the dense set based on Coq's fast rational numbers. Thirdly, we extend the hierarchy to capture order on undecidable structures, while it was limited to decidable structures before. This hierarchy, based on type classes, allows us to share theory on the naturals, integers, rationals, dyadics, and reals in a convenient way. Finally, we obtain another dramatic speed-up by avoiding evaluation of termination proofs at runtime.
description: arXiv admin note: text overlap with arXiv:1105.2751
UVA and endogenous photosensitizers – the detection of singlet oxygen by its luminescence
Creators: name: Bäumler, Wolfgang
name: Regensburger, Johannes
name: Knak, Alena
name: Felgenträger, Ariane
name: Maisch, Tim
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie
subject: 610 Medizin

description: UVA irradiation (320–400 nm) comprises about 95 percent of incident midday solar ultraviolet irradiation. It penetrates skin much deeper than UVB irradiation. The absorption of UVA irradiation in endogenous chromophores frequently leads to the generation of reactive oxygen species such as singlet oxygen (1O2). 1O2 is an important biochemical intermediate in multiple biological processes. Beside other procedures, the direct detection of 1O2 by its luminescence is a powerful tool that helps to understand the generation of 1O2 during UVA exposure in solution, in vitro and in vivo. This article describes the endogenous photosensitizers, their ability to generate 1O2 under UVA irradiation, and the detection technology to visualize the action of 1O2.
Oxygen and temperature sensitivity of blue to green to yellow light-emitting Pt(II) complexes
Creators: name: Karakus, C.
name: Fischer, Lorenz
name: Schmeding, S.
name: Hummel, J.
name: Risch, N.
name: Schäferling, Michael
name: Holder, Elisabeth
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: The synthesis and photophysical properties of a series of yellow-green to blue-green emitting heteroleptic, cyclometalated Pt(II)(acac) complexes based on substituted phenylpyridine and tetrahydroquinoline ligands is reported. The luminescence intensities and lifetimes of these compounds were also studied in poly(styrene) films with respect to their responses to oxygen and temperature. Particularly, due to the insensitivity to oxygen quenching, these complexes are promising candidates as inert reference dyes in optical sensors. On the other hand, the Pt(II) complex with 2-(4-bromophenyl)-5,6,7,8-tetrahydroquinoline as C^N ligand, displays a strong temperature quenching effect. The distinct response to temperature was additionally calibrated after incorporation in poly(vinylidene chloride-co-acrylonitrile) serving as oxygen-blocking matrix copolymer. The resulting yellow-green-emitting temperature sensor signifies an interesting alternative to the available mostly red emitting temperature-sensitive probes.
Constraining the quadrupole moment of stellar-mass black-hole candidates with the continuum fitting method
Creators: name: Bambi, Cosimo
name: Barausse, Enrico
Publisher: name: arXiv
Year: 2010
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Black holes in General Relativity are known as Kerr black holes and are characterized solely by two parameters, the mass $M$ and the spin $J$. All the higher multipole moments of the gravitational field are functions of these two parameters. For instance, the quadrupole moment is $Q=-J^2/M$, which implies that a measurement of $M$, $J$, and $Q$ for black hole candidates would allow one to test whether these objects are really black holes as described by General Relativity. While future gravitational-wave experiments will be able to test the Kerr nature of these objects with very high accuracy, in this paper we show that it is possible to put constraints on the quadrupole moment of stellar-mass black hole candidates by using presently available X-ray data of the thermal spectrum of their accretion disk.
description: 15 pages, 10 figures. Corrected typo in Eq. 6, see erratum [ApJ (2015) 813, 79] for more details. Astrophys.J.731:121,2011
Voting fast and voting slow : a dynamic dual processes account of voter decision-making
Creators: name: Lockhart, Mackenzie
Publisher: name: University of British Columbia
Year: 2017

description: This thesis builds on previous work in dual process theory. Dual process theory argues that decisions are made based on two systems: one that is fast and one that is automatic. Based on evidence from psychological research, I argue that contextual cues such as the way voting is framed and the information available to voters should affect the way these two systems are used. When voters have more developed affective feelings or are manipulated to feel as if vote choice is an affective decision, they should be less likely to engage in cognitive reasoning. Using experimental and observational data from an experimental dataset, I demonstrate that the nature of online tallies (as proposed by Lodge, Stroh, and McGraw 1989) has a strong effect on how rational strategies are employed and that the framing of a decision as affective causes voters to make their vote choice more quickly. This work contributes two main pieces to the literature. First, using a novel design to demonstrate the two processes acting concurrently adds weight to the generalizability of dual process theory as previous research has been criticized for it’s lack of realism. Second, it demonstrates that the dual processes are dynamic and their role in vote choice depends on contextual clues.
title: Computational generation of hepatic vascular trees using mathematical optimization
Creators: name: Jessen, Etienne
Publisher: name: UNSPECIFIED
Year: 2025

description: The human vasculature is crucial for the efficient distribution of oxygen and nutrients but is susceptible to various diseases. Early detection of these diseases and an accurate prediction of disease progression remain challenging, exacerbated by the limited resolution of in-vivo imaging techniques. Furthermore, many physiological phenomena still are poorly understood, making organ functional assessment difficult.

In response, computational methods were developed, the goal of which is to generate missing vascular trees starting from initial images. Since these methods are based on optimality principles, the generated trees can also help to improve the functional assessment, specifically to understand the goals and constraints guiding vascular growth and development. Constrained Constructive Optimization (CCO) is the most widely used method for generating synthetic trees. While CCO offers a framework for tree generation, it only uses local optimization methods, which hinder a qualitative comparison to real vascular trees. Additionally, the algorithm suffers from poor computational complexity, making generating vascular trees down to the microcirculation impractical.

The main objective of this thesis is to overcome these limitations and propose a novel framework capable of generating vascular trees up to the microcirculation using global optimization methods. We achieve this by splitting the optimization problem into a discrete topology and a continuous geometry part. The global geometry of a tree is optimized using a nonlinear optimization problem (NLP), which also allows us to change the associated cost and constraint functions easily. By extending the NLP with a set of medial balls and distance constraints, we can also constrain multiple trees inside the same nonconvex boundary while avoiding intersections. We use a metaheuristic approach based on Simulated Annealing (SA) for the global topology and introduce an efficient way of changing the topology, which only scales with the depth of the tree. The complete framework combines both parts in an algorithmic approach, which is efficient and flexible.

Utilizing this new framework's flexibility, we investigate the validity of Murray's law, which is the basis of most generation frameworks. By not enforcing Murray's law, we can generate branching patterns, which are much closer to experimental values, supporting recent studies against the use of Murray's law in clinical guidelines. We further test our new framework against multiple benchmark problems, such as the vascular corrosion cast of a human liver and the anatomical region of the brain. In contrast to local methods like CCO, our framework significantly reduces the metabolic cost of its generated trees, leading to more natural geometries comparable to medical images.
Finite element systems of differential forms
Creators: name: Christiansen, Snorre Harald
Publisher: name: arXiv
Year: 2010
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 65N30

description: We develop the theory of mixed finite elements in terms of special inverse systems of complexes of differential forms, defined over cellular complexes. Inclusion of cells corresponds to pullback of forms. The theory covers for instance composite piecewise polynomial finite elements of variable order over polyhedral grids. Under natural algebraic and metric conditions, interpolators and smoothers are constructed, which commute with the exterior derivative and whose product is uniformly stable in Lebesgue spaces. As a consequence we obtain not only eigenpair approximation for the Hodge-Laplacian in mixed form, but also variants of Sobolev injections and translation estimates adapted to variational discretizations.
description: 43 pages
Conformational control of benzophenone-sensitized charge transfer in dinucleotides
Creators: name: Merz, Thomas
name: Wenninger, M.
name: Weinberger, Michael
name: Riedle, E.
name: Wagenknecht, Hans-Achim
name: Schütz, Martin
Publisher: name: Universität Regensburg
Year: 2013
Subjects: subject: 540 Chemie

description: Charge transfer in DNA cannot be understood without addressing the complex conformational flexibility, which occurs on a wide range of timescales. In order to reduce this complexity four dinucleotide models 1X consisting of benzophenone linked by a phosphodiester to one of the natural nucleosides X = A, G, T, C were studied in water and methanol. The theoretical work focuses on the dynamics and electronic structure of 1G. Predominant conformations in the two solvents were obtained by molecular dynamics simulations. 1G in MeOH adopts mainly an open geometry with a distance of 12–16 Å between the two aromatic parts. In H2O the two parts of 1G form primarily a stacked conformation yielding a distance of 5–6 Å. The low-lying excited states were investigated by electronic structure theory in a QM/MM environment for representative snapshots of the trajectories. Photo-induced intramolecular charge transfer in the S1 state occurs exclusively in the stacked conformation. Ultrafast transient absorption spectroscopy with 1X reveals fast charge transfer from S1 in both solvents with varying yields. Significant charge transfer from the T1 state is only found for the nucleobases with the lowest oxidation potential: in H2O, charge transfer occurs with 3.2 × 109 s−1 for 1A and 6.0 × 109 s−1 for 1G. The reorganization energy remains nearly unchanged going from MeOH to the more polar H2O. The electronic coupling is rather low even for the stacked conformation with HAB = 3 meV and explains the moderate charge transfer rates. The solvent controls the conformational distribution and therefore gates the charge transfer due to differences in distance and stacking.
Tate curves and UHF-algebras
Creators: name: Nikolaev, Igor
Publisher: name: arXiv
Year: 2010
Subjects: subject: Number Theory (math.NT)
subject: Operator Algebras (math.OA)
subject: FOS: Mathematics
subject: 11G07, 46L85

description: It is proved that (a stabilization of) the norm-closure of a self- adjoint representation of the twisted homogeneous coordinate ring of a Tate curve contains a copy of the UHF-algebra.
description: to appear Indagationes Mathematicae
Impact of Rotation-Driven Particle Repopulation on the Thermal Evolution of Pulsars
Creators: name: Negreiros, Rodrigo
name: Schramm, Stefan
name: Weber, Fridolin
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Driven by the loss of energy, isolated rotating neutron stars (pulsars) are gradually slowing down to lower frequencies, which increases the tremendous compression of the matter inside of them. This increase in compression changes both the global properties of rotating neutron stars as well as their hadronic core compositions. Both effects may register themselves observationally in the thermal evolution of such stars, as demonstrated in this Letter. The rotation-driven particle process which we consider here is the direct Urca (DU) process, which is known to become operative in neutron stars if the number of protons in the stellar core exceeds a critical limit of around 11% to 15%. We find that neutron stars spinning down from moderately high rotation rates of a few hundred Hertz may be creating just the right conditions where the DU process becomes operative, leading to an observable effect (enhanced cooling) in the temperature evolution of such neutron stars. As it turns out, the rotation-driven DU process could explain the unusual temperature evolution observed for the neutron star in Cas A, provided the mass of this neutron star lies in the range of 1.5 to 1.9 \msun and its rotational frequency at birth was between 40 (400 Hz) and 70% (800 Hz) of the Kepler (mass shedding) frequency, respectively.
description: Revised version, 7 pages 4 figures. To appear in Physics Letters B
Bell inequalities for the simplest exclusivity graph
Creators: name: Sadiq, Muhamad
name: Badziag, Piotr
name: Bourennane, Mohamed
name: Cabello, Adan
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Which is the simplest logical structure for which there is quantum nonlocality? We show that there are only three bipartite Bell inequalities with quantum violation associated with the simplest graph of relationships of exclusivity with a quantum-classical gap. These are the most elementary logical Bell inequalities. We show that the quantum violation of some well-known Bell inequalities is related to them. We test the three Bell inequalities with pairs of polarization-entangled photons and report violations in good agreement with the quantum predictions. Unlike other experiments testing noncontextuality inequalities with pentagonal exclusivity, the ones reported here are free of the compatibility loophole.
description: REVTeX4, 6 pages, 4 figures
Ramsey Properties of Permutations
Creators: name: Böttcher, Julia
name: Foniok, Jan
Publisher: name: arXiv
Year: 2011
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05D10, 05C55, 03C52

description: The age of each countable homogeneous permutation forms a Ramsey class. Thus, there are five countably infinite Ramsey classes of permutations.
description: 10 pages, 3 figures; v2: updated info on related work + some other minor enhancements (Dec 21, 2012)
Stepwise activation of “non-innocent” Cp* substituents – a Cp* based cascade reaction
Creators: name: Stubenhofer, Markus
name: Lassandro, Giuliano
name: Balazs, Gabor
name: Timoshkin, Alexey Y.
name: Scheer, Manfred
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: Reactions of Cp* substituted pentelidene complexes with the primary phosphine Cp*PH2 yield novel polycyclic phosphorus/arsenic and carbon containing cage compounds via cascade-like reactions. These reactions include a sequence of nucleophilic addition reactions, intramolecular hydrophosphination (partially hydroarsination) reactions, retro-Diels–Alder reactions with Cp*H elimination and subsequent [2+4]-cycloadditions.
Complete bipartite graphs whose topological symmetry groups are polyhedral
Creators: name: Mellor, Blake
Publisher: name: arXiv
Year: 2011
Subjects: subject: Geometric Topology (math.GT)
subject: FOS: Mathematics

description: We determine for which $n$, the complete bipartite graph $K_{n,n}$ has an embedding in $S^3$ whose topological symmetry group is isomorphic to one of the polyhedral groups: $A_4$, $A_5$, or $S_4$.
description: 25 pages, 6 figures, latest version has minor edits in preparation for submission
Artin-Tate motivic sheaves with finite coefficients over an algebraic variety
Creators: name: Positselski, Leonid
Publisher: name: arXiv
Year: 2010
Subjects: subject: K-Theory and Homology (math.KT)
subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics

description: We propose a construction of a tensor exact category F_X^m of Artin-Tate motivic sheaves with finite coefficients Z/m over an algebraic variety X (over a field K of characteristic prime to m) in terms of etale sheaves of Z/m-modules over X. Among the objects of F_X^m, in addition to the Tate motives Z/m(j), there are the cohomological relative motives with compact support M_cc^m(Y/X) of varieties Y quasi-finite over X. Exact functors of inverse image with respect to morphisms of algebraic varieties and direct image with compact supports with respect to quasi-finite morphisms of varieties Y\to X act on the exact categories F_X^m. Assuming the existence of triangulated categories of motivic sheaves DM(X,Z/m) over algebraic varities X over K and a weak version of the "six operations" in these categories, we identify F_X^m with the exact subcategory in DM(X,Z/m) consisting of all the iterated extensions of the Tate twists M_cc^m(Y/X)(j) of the motives M_cc^m(Y/X). An isomorphism of the Z/m-modules Ext between the Tate motives Z/m(j) in the exact category F_X^m with the motivic cohomology modules predicted by the Beilinson-Lichtenbaum etale descent conjecture (recently proven by Voevodsky, Rost, et al.) holds for smooth varieties X over K if and only if the similar isomorphism holds for Artin-Tate motives over fields containing K. When K contains a primitive m-root of unity, the latter condition is equivalent to a certain Koszulity hypothesis, as it was shown in our previous paper arXiv:1006.4343
description: LaTeX 2e, 34 pages; v.4: additions in the introduction and section 10, several references added; v.5: several misprints corrected, reference updated -- this is intended as the final version
Modeling and Analysis of K-Tier Downlink Heterogeneous Cellular Networks
Creators: name: Dhillon, Harpreet S.
name: Ganti, Radha Krishna
name: Baccelli, Francois
name: Andrews, Jeffrey G.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Cellular networks are in a major transition from a carefully planned set of large tower-mounted base-stations (BSs) to an irregular deployment of heterogeneous infrastructure elements that often additionally includes micro, pico, and femtocells, as well as distributed antennas. In this paper, we develop a tractable, flexible, and accurate model for a downlink heterogeneous cellular network (HCN) consisting of K tiers of randomly located BSs, where each tier may differ in terms of average transmit power, supported data rate and BS density. Assuming a mobile user connects to the strongest candidate BS, the resulting Signal-to-Interference-plus-Noise-Ratio (SINR) is greater than 1 when in coverage, Rayleigh fading, we derive an expression for the probability of coverage (equivalently outage) over the entire network under both open and closed access, which assumes a strikingly simple closed-form in the high SINR regime and is accurate down to -4 dB even under weaker assumptions. For external validation, we compare against an actual LTE network (for tier 1) with the other K-1 tiers being modeled as independent Poisson Point Processes. In this case as well, our model is accurate to within 1-2 dB. We also derive the average rate achieved by a randomly located mobile and the average load on each tier of BSs. One interesting observation for interference-limited open access networks is that at a given SINR, adding more tiers and/or BSs neither increases nor decreases the probability of coverage or outage when all the tiers have the same target-SINR.
description: IEEE Journal on Selected Areas in Communications, vol. 30, no. 3, pp. 550 - 560, Apr. 2012
Spin crossover in phosphorus- and arsenic-bridged cyclopentadienyl-manganese(II) dimers
Creators: name: Scheuermayer, S.
name: Tuna, F.
name: Bodensteiner, Michael
name: Scheer, Manfred
name: Layfield, Richard A.
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: Manganocene reacts with LiE(SiMe3)2 (E = P or As) to give [(η5-Cp)Mn{μ-E(SiMe3)2}]2, where E = P (1) or As (2). The temperature dependence of the magnetic susceptibility in 1 and 2 is due to antiferromagnetic exchange and to spin-crossover (SCO). Compound 2 shows two-step SCO with hysteresis, involving high-spin (S = 5/2) and intermediate-spin S = (3/2) Mn(II).
Zero-Divisors of Content Algebras
Creators: name: Nasehpour, Peyman
Publisher: name: arXiv
Year: 2010
Subjects: subject: Commutative Algebra (math.AC)
subject: FOS: Mathematics

description: In this article, we prove that in content extentions minimal primes extend to minimal primes and discuss zero-divisors of a content algebra over a ring who has Property (A) or whose set of zero-divisors is a finite union of prime ideals. We also examine the preservation of diameter of zero-divisor graph under content extensions.
description: Published at ARCHIVUM MATHEMATICUM (BRNO) Tomus 46 (2010), 237-249. arXiv admin note: substantial text overlap with arXiv:0807.1835, arXiv:1208.5637
Stoichiometry-controlled FeP nanoparticles synthesized from a single source precursor
Creators: name: Hunger, Cornelia
name: Ojo, Wilfried-Solo
name: Bauer, Susanne
name: Xu, Shu
name: Zabel, Manfred
name: Chaudret, Bruno
name: Lacroix, Lise-Marie
name: Scheer, Manfred
Publisher: name: Universität Regensburg
Year: 2013
Subjects: subject: 540 Chemie

description: Phase-pure FeP nanoparticles (NPs) have been synthesized through low temperature thermolysis of the single source precursor [(CO)4Fe(PH3)]. Examination of the mechanism demonstrates the central role of the labile CO ligands and the weak P–H bonds to yield stoichiometry controlled FeP materials.
Synthesis of heteroatomic Zintl anions in liquid ammonia – the new highly charged [Sn4Bi4]4− and fully ordered [Sn2Bi2]2−
Creators: name: Friedrich, Ute
name: Neumeier, Maria
name: Koch, Carina
name: Korber, Nikolaus
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: The new Zintl anion [Sn4Bi4]4−, synthesized by dissolving CsSnBi in liquid ammonia, forms a monocapped nortricyclane-like cage. Its electron localization function (ELF) analysis shows evidence for 3-centre bonding. The analogous reaction with KSnBi results in a crystallographically fully ordered tetrahedral [Sn2Bi2]2− ion.
The imagined pilgrimage of Sir John Mandeville's late medieval Book of Marvels and Travels
Creators: name: Drzazgowski, Kyla Helena
Publisher: name: University of British Columbia
Year: 2017

description: This thesis investigates two main topics: the medieval practice of imagined pilgrimage and a Middle English text called the Book of Marvels and Travels (1350s). While recent historical and literary scholarship has helped to uncover how English monastic audiences engaged in imagined pilgrimage, which is the act of going on a holy journey in spirit rather than in body, less work has been done to explore how secular English audiences turned to texts to undertake non-physical journeys. The focal point of medieval European pilgrimage, Jerusalem was largely out of reach for many medieval English men and women due to a variety of personal, political, and economic reasons. Imagined pilgrimage texts such as the Book fulfilled a need in readers for an alternative means to attain the same spiritual benefits that physical pilgrimage offered its participants. Employing an interdisciplinary approach to the study of the literary history of imagined pilgrimage, in this project I offer a new reading of the Book and investigate both the history of pilgrimage writing and the complex monastic and secular debates surrounding the shifting benefits, dangers, and definitions of physical and imagined holy travel. Presented by a narrator who identifies himself as a knight named “John Mandeville,” the Book provided its medieval English reader-pilgrims with the information needed to make imaginative pilgrimages to the Holy Land and the Eastern world that lies beyond it.
Enantioselective synthesis of (−)-paeonilide
Creators: name: Harrar, Klaus
name: Reiser, Oliver
Publisher: name: Universität Regensburg
Year: 2012
Subjects: subject: 540 Chemie

description: The first enantioselective synthesis of (−)-paeonilide is reported. Starting from inexpensive furan-3-carboxylic acid the targeted monoterpene was obtained in 12 steps via an asymmetric cyclopropanation-lactonization cascade and a stereoselective side chain insertion at an acetal-like position.
On the physisorption of water on graphene: a CCSD(T) study
Creators: name: Voloshina, Elena
name: Usvyat, Denis
name: Schütz, Martin
name: Dedkov, Yuriy
name: Paulus, Beate
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The electronic structure of the zero-gap two-dimensional graphene has a charge neutrality point exactly at the Fermi level that limits the practical application of this material. There are several ways to modify the Fermi-level-region of graphene, e.g. adsorption of graphene on different substrates or different molecules on its surface. In all cases the so-called dispersion or van der Waals interactions can play a crucial role in the mechanism, which describes the modification of electronic structure of graphene. The adsorption of water on graphene is not very accurately reproduced in the standard density functional theory (DFT) calculations and highly-accurate quantum-chemical treatments are required. A possibility to apply wavefunction-based methods to extended systems is the use of local correlation schemes. The adsorption energies obtained in the present work by means of CCSD(T) are much higher in magnitude than the values calculated with standard DFT functional although they agree that physisorption is observed. The obtained results are compared with the values available in the literature for binding of water on the graphene-like substrates.
TransverseDiff gravity is to scalar-tensor as unimodular gravity is to General Relativity
Creators: name: Lopez-Villarejo, J. J.
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Transverse Diffeomorphism (TDiff) theories are well-motivated theories of gravity from the quantum perspective, which are based upon a gauge symmetry principle. The main contribution of this work is to firmly establish a correspondence between TransverseDiff and the better-known scalar-tensor gravity --- in its more general form ---, a relation which is completely analogous to that between unimodular gravity and General Relativity. We then comment on observational aspects of TDiff. In connection with this proof, we derive a very general rule that determines under what conditions the procedure of fixing a gauge symmetry can be equivalently applied before the variational principle leading to the equations of motion, as opposed to the standard procedure, which takes place afterwards; this rule applies to gauge-fixing terms without derivatives.
description: 10 pages; amsart style; v3: version as appeared in JCAP, redaction improved
Hadamard States for the Vector Potential on Asymptotically Flat Spacetimes
Creators: name: Dappiaggi, Claudio
name: Siemssen, Daniel
Publisher: name: arXiv
Year: 2011
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 81T05, 81T20

description: We develop a quantization scheme for the vector potential on globally hyperbolic spacetimes which realizes it as a locally covariant conformal quantum field theory. This result allows us to employ on a large class of backgrounds, which are asymptotically flat at null infinity, a bulk-to-boundary correspondence procedure in order to identify for the underlying field algebra a distinguished ground state which is of Hadamard form.
description: 25 pages, comments added, improved notation, minor typos corrected and updated bibliography
Why BLUF photoreceptors with roseoflavin cofactors lose their biological functionality
Creators: name: Merz, Thomas
name: Sadeghian, Keyarash
name: Schütz, Martin
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The photophysics of roseoflavin in three different environments is investigated by using ab initio and quantum mechanics/molecular mechanics methods. Intramolecular charge transfer is shown to be responsible for the quenching of the fluorescence in the gas phase, and in the water environment. However, for the roseoflavin incorporated into the blue light using flavin (BLUF) protein environment (substituting the native flavin) no such deactivation is found. The conical intersection between the locally excited state of the chromophore and the charge transfer state involving the tyrosine residue, which in the native BLUF domain is responsible for initiating the photocycle, is missing for the roseoflavin substituted protein. This explains the experimental observations of the lack of any photocycle, and the loss of the biological function of the BLUF photoreceptor reported earlier.
Single-molecule chemistry and physics explored by low-temperature scanning probe microscopy
Creators: name: Swart, Ingmar
name: Gross, Leo
name: Liljeroth, Peter
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 530 Physik
subject: 540 Chemie

description: It is well known that scanning probe techniques such as scanning tunnelling microscopy (STM) and atomic force microscopy (AFM) routinely offer atomic scale information on the geometric and the electronic structure of solids. Recent developments in STM and especially in non-contact AFM have allowed imaging and spectroscopy of individual molecules on surfaces with unprecedented spatial resolution, which makes it possible to study chemistry and physics at the single molecule level. In this feature article, we first review the physical concepts underlying image contrast in STM and AFM. We then focus on the key experimental considerations and use selected examples to demonstrate the capabilities of modern day low-temperature scanning probe microscopy in providing chemical insight at the single molecule level.
The horoboundary and isometry group of Thurston's Lipschitz metric
Creators: name: Walsh, Cormac
Publisher: name: arXiv
Year: 2010
Subjects: subject: Geometric Topology (math.GT)
subject: Metric Geometry (math.MG)
subject: FOS: Mathematics

description: We show that the horofunction boundary of Teichmüller space with Thurston's Lipschitz metric is the same as the Thurston boundary. We use this to determine the isometry group of the Lipschitz metric, apart from in some exceptional cases. We also show that the Teichmüller spaces of different surfaces, when endowed with this metric, are not isometric, again with some possible exceptions of low genus.
description: 23 pages, 5 figures. There was a mistake in one of the lemmas. Fixing it required replacing Lemmas 7.5, 7.6, and 7.7. The new version is very close to the published version
Synthesis and structure of cationic guanidinate-bridged bimetallic {Li7M} cubes (M = Mn, Co, Zn) with inverse crown counter anions
Creators: name: Woodruff, D.
name: Bodensteiner, Michael
name: Sells, D. O.
name: Winpenny, Richard. E. P.
name: Layfield, Richard A.
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The reactions of the heteroleptic lithium amide [Li3(μ-hmds)2(μ,μ-hpp)] (1), where [hmds]− = hexamethyldisilazide and [hpp]− = hexahydropyrimidopyrimidide, with MnCl2, CoCl2 or ZnBr2 result in the formation of the separated ion-pairs [MLi7(μ8-O)(μ,μ-hpp)6]+[A]−, which each consist of a {MLi7} oxo-centred cube structural motif (M = Mn 2, Co 4, Zn 5), with each face of the cube being bridged by an [hpp]− ligand. In the case of M = Mn and Co, the counter ion, [A]−, is the pentagonal anionic inverse crown [{Li(μ-hmds)}5(μ5-Cl)]− (3), whereas the reaction with M = Zn produces the known tris-amido zincate [Zn(hmds)3]− counter anion.
Improvement of (bipy)Pt(XR)2 (X = O, S) type photosensitizers by covalent dye attachment
Creators: name: Pevny, Florian
name: Zabel, Manfred
name: Winter, Rainer F.
name: Rausch, Andreas
name: Yersin, Hartmut
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: Irradiation into the dye-based absorption band of complexes (tBu2bipy)Pt(SR)2 and (tBu2bipy)Pt(OR)2 where R denotes a coumarine-based thiolate and alkoxolate substituent populates the same excited triplet state as is obtained by excitation into the much weaker (RX)2Pt→tBu2bipy (X = O, S) charge-transfer band. This paves the way toward more efficient photosensitizers.
Spatially resolved ingredient detection in spice mixes using 3D convolutional neural networks
Creators: name: Anastasiadis, Johannes
name: Krippner, Wolfgang
name: Puente Léon, Fernando
Publisher: name: Karlsruhe
Year: 2019

description: Abstract A method using spectral information to detect substances in mixtures is given. The presented convolutional neural network is using three-dimensional convolutions to process hyperspectral images. Reflectance values can be fed directly into the network and are not preprocessed. Due to the architecture, the neural network performs a spatially invariant operation. Detection performance is demonstrated by a dataset containing spice mixtures.
N-Sulfonic acid modified poly(styrene-co-maleic anhydride): An efficient and recyclable solid acid catalyst for the synthesis of a wide range of spiropyrans
Creators: name: Mommahed Heravi, Majid
name: Hashemi, Elaheh
name: Azimian, Fereshteh
Publisher: name: figshare
Year: 2022
Subjects: subject: 30302 Nanochemistry and Supramolecular Chemistry
subject: FOS: Chemical sciences
subject: 30701 Quantum Chemistry
subject: 39904 Organometallic Chemistry
subject: Organic Chemistry
subject: 30502 Natural Products Chemistry
subject: 30599 Organic Chemistry not elsewhere classified
subject: 30205 Non-metal Chemistry
subject: Nuclear Chemistry
subject: 30504 Organic Green Chemistry
subject: 30303 Optical Properties of Materials

description: N-Sulfonic acid modified poly(styrene-co-maleic anhydride) as a recyclable solid acid catalyst efficiently catalyzed the one-pot three-component synthesis of spiropyran derivatives through a simple, convenient, and cost-effective approach in good yields and selectivity.
Optimal Uncertainty Quantification
Creators: name: Owhadi, Houman
name: Scovel, Clint
name: Sullivan, Timothy John
name: McKerns, Mike
name: Ortiz, Michael
Publisher: name: arXiv
Year: 2010
Subjects: subject: Probability (math.PR)
subject: Information Theory (cs.IT)
subject: Statistics Theory (math.ST)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: We propose a rigorous framework for Uncertainty Quantification (UQ) in which the UQ objectives and the assumptions/information set are brought to the forefront. This framework, which we call \emph{Optimal Uncertainty Quantification} (OUQ), is based on the observation that, given a set of assumptions and information about the problem, there exist optimal bounds on uncertainties: these are obtained as values of well-defined optimization problems corresponding to extremizing probabilities of failure, or of deviations, subject to the constraints imposed by the scenarios compatible with the assumptions and information. In particular, this framework does not implicitly impose inappropriate assumptions, nor does it repudiate relevant information. Although OUQ optimization problems are extremely large, we show that under general conditions they have finite-dimensional reductions. As an application, we develop \emph{Optimal Concentration Inequalities} (OCI) of Hoeffding and McDiarmid type. Surprisingly, these results show that uncertainties in input parameters, which propagate to output uncertainties in the classical sensitivity analysis paradigm, may fail to do so if the transfer functions (or probability distributions) are imperfectly known. We show how, for hierarchical structures, this phenomenon may lead to the non-propagation of uncertainties or information across scales. In addition, a general algorithmic framework is developed for OUQ and is tested on the Caltech surrogate model for hypervelocity impact and on the seismic safety assessment of truss structures, suggesting the feasibility of the framework for important complex systems. The introduction of this paper provides both an overview of the paper and a self-contained mini-tutorial about basic concepts and issues of UQ.
description: 90 pages. Accepted for publication in SIAM Review (Expository Research Papers). See SIAM Review for higher quality figures
Classification of real Bott manifolds and acyclic digraphs
Creators: name: Choi, Suyoung
name: Masuda, Mikiya
name: Oum, Sang-il
Publisher: name: arXiv
Year: 2010
Subjects: subject: Algebraic Topology (math.AT)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: Primary 37F20, 57R91, 05C90, Secondary 53C25, 14M25

description: We completely characterize real Bott manifolds up to affine diffeomorphism in terms of three simple matrix operations on square binary matrices obtained from strictly upper triangular matrices by permuting rows and columns simultaneously. We also prove that any graded ring isomorphism between the cohomology rings of real Bott manifolds with $\mathbb Z/2$ coefficients is induced by an affine diffeomorphism between the real Bott manifolds. Our characterization can also be described in terms of graph operations on directed acyclic graphs. Using this combinatorial interpretation, we prove that the decomposition of a real Bott manifold into a product of indecomposable real Bott manifolds is unique up to permutations of the indecomposable factors. Finally, we produce some numerical invariants of real Bott manifolds from the viewpoint of graph theory and discuss their topological meaning. As a by-product, we prove that the toral rank conjecture holds for real Bott manifolds.
description: 27 pages, 5 figures. It is a combination of arXiv:0809.2178 and arXiv:1002.4704, including some new results
Intramolecular monomer-on-monomer (MoM) Mitsunobu cyclization for the synthesis of benzofused thiadiazepine-dioxides
Creators: name: Maity, P.
name: Kainz, Quirin
name: Faisal, Saqib
name: Rolfe, Alan
name: Samarakoon, T.
name: Basha, F.
name: Reiser, Oliver
name: Hanson, P.
Publisher: name: Universität Regensburg
Year: 2011
Subjects: subject: 540 Chemie

description: The utilization of a monomer-on-monomer (MoM) intramolecular Mitsunobu cyclization reaction employing norbornenyl-tagged (Nb-tagged) reagents is reported for the synthesis of benzofused thiadiazepine-dioxides. Facile purification was achieved viaring-opening metathesis (ROM) polymerization initiated by one of three metathesis catalyst methods: (i) free metathesis catalyst, (ii) surface-initiated catalyst-armed silica, or (iii) surface-initiated catalyst-armed Co/C magnetic nanoparticles.