Analytic expression for Taylor-Couette stability boundary

We analyze the mechanism that determines the boundary of stability in Taylor-Couette flow. By simple physical argument we derive an analytic expression to approximate the stability line for all radius ratios and all speed ratios, for co- and counterrotating cylinders. The expression includes viscosity and so generalizes Rayleigh's criterion. We achieve agreement with linear stability theory and with experiments in the whole parameter space. Explicit formulae are given for limiting cases.Comment: 6 pages (LaTeX with REVTEX) including 4 figures (Postscript) Revised, discussion of two additional references. See also http://staff-www.uni-marburg.de/~esse

CLT Shearwall Dovetail Connection

As cross-laminated timber has become an increasingly popular construction material, its use as a shear wall element has also demanded attention. Primary obstructions to the use of CLT shear walls have been the lack of an economic connection type that does not compromise the structural integrity and has the robustness that CLT shear wall panels deserve. Dovetail connections provide a great option for the connection of CLT shear walls. With more experimentation, the optimal dovetail geometry can be further developed. The small-scale testing done in conjunction with this report proved that very deep pins and tails will result in bearing failures at the joints. If the depth of the pins and tails is too short, the results from tests show that the dovetail will fail in bending along the neck of the joint. In order to duplicate the results of this report it is important to choose the correct geometry of the test-specimen

Kompaktierung orthogonaler Zeichnungen - Entwicklung und Analyse eines IP-basierten Algorithmus

Diese Arbeit befasst sich mit dem zweidimensionalen Kompaktierungsproblem für orthogonale Zeichnungen. Ziel ist es, allen Knoten Koordinaten zuzuweisen, sodass die Gesamtkantenlänge minimiert wird, die Form der Zeichnung aber erhalten bleibt. Viele Kompaktierungsheuristiken, insbesondere eindimensionale, treffen lokale Entscheidungen, beispielsweise, wie Dissecting-Kanten angeordnet werden sollen oder in welche Richtung zuerst kompaktiert wird. Ungünstige lokale Entscheidungen können jedoch zu einer höheren Gesamtkantenlänge führen. In dieser Arbeit wird daher eine zweidimensionale Kompaktierungsheuristik für 2-zusammenhängende, 4-planare Graphen vorgestellt, die die Ausrichtung der Dissecting-Kanten offen lässt und keine Richtung bevorzugt. Das Optimierungsproblem wird als IP formuliert, um die parallele Kompaktierung in beide Dimensionen zu gewährleisten. Erst beim Lösen dieses IP wird die Ausrichtung der Dissecting-Kanten festgelegt. Unter bestimmten Voraussetzungen ist die Nebenbedingungsmatrix des IP total unimodular. Eine experimentelle Analyse zeigt abschließend, dass der vorgestellte Ansatz teilweise Zeichnungen mit geringerer Gesamtkantenlänge liefert als bekannte Heuristiken

Low Weight Discrete Logarithms and Subset Sum in 20.65n2^{0.65n} with Polynomial Memory

We propose two polynomial memory collision finding algorithms for the low Hamming weight discrete logarithm problem in any abelian group $G$. The first one is a direct adaptation of the Becker-Coron-Joux (BCJ) algorithm for subset sum to the discrete logarithm setting. The second one significantly improves on this adaptation for all possible weights using a more involved application of the representation technique together with some new Markov chain analysis. In contrast to other low weight discrete logarithm algorithms, our second algorithm\u27s time complexity interpolates to Pollard\u27s $|G|^{\frac 1 2}$ bound for general discrete logarithm instances. We also introduce a new subset sum algorithm with polynomial memory that improves on BCJ\u27s $2^{0.72n}$ time bound for random subset sum instances $a_1, \ldots, a_n, t \in \mathbb{Z}_{2^n}$. Technically, we introduce a novel nested collision finding for subset sum -- inspired by the NestedRho algorithm from Crypto \u2716 -- that recursively produces collisions. We first show how to instantiate our algorithm with run time $2^{0.649n}$. Using further tricks, we are then able to improve its complexity down to $2^{0.645n}$

Ground state structure of diluted antiferromagnets and random field systems

A method is presented for the calculation of all exact ground states of diluted antiferromagnets and random field systems in an arbitrary range of fields. It works by calculating all jump-fields B,\Delta where the system changes it's ground state. For each field value all degenerated ground states are represented by a set of (anti-) ferromagnetic clusters and a relation between the clusters. So a complete description of the ground state structure of these systems is possible. Systems are investigated up to size 48^3 on the whole field-range and up to 160^3 for some particular fields. The behavior of order parameters is investigated, the number of jumps is analyzed and the degree of degeneracy as functions of size and fields is calculated.Comment: 11 pages, 13 figures, LaTex, submitted to Physica

Left ventricular M-mode prediction intervals in 7651 dogs: Population-wide and selected breed-specific values

Background: Echocardiography is a common method to measure heart size in dogs. The heart dimensions are influenced by body weight (BW) and potentially by breed.Objectives: To establish BW-dependent prediction intervals (PIs) of the left ventricular (LV) linear dimensions in a population of dogs of many breeds in multicenter environment, and to identify breeds deviating from these intervals.Dogs: Seven thousand six hundred and fifty-one dogs.Methods: Retrospectively, data from heart screens conducted between 2009 and 2016 were included. Cardiac dimensional PIs were generated using allometric scaling including all nonsighthound dogs and values were compared to previously published PIs. The values measured in dogs of respective breeds, including sighthounds, were then compared to the overall nonsighthound PIs to identify deviant breeds. The interobserver-variability of the measurements was determined using the explained residual variance.Results: Prediction intervals for the nonsighthound dogs were in agreement with previously published cardiac PIs, although the upper limits of the generated PIs of our study were slightly below those currently applied (except the interventricular septum in systole and the left ventricular free wall in diastole below 10.0 kg and 15.0 kg, respectively). Values measured in the nonsighthound breed Newfoundland deviated for most dimensions. Most of the sighthound breeds analyzed had greater cardiac dimensions, with the exception of the Irish Wolfhound.Conclusion and Importance: Findings of our study reinforces the value of BW-dependent PIs for cardiac dimensions in dogs and suggest that these PIs are valid for most nonsighthound breeds, but not the sighthound breeds

McEliece needs a Break -- Solving McEliece-1284 and Quasi-Cyclic-2918 with Modern ISD

With the recent shift to post-quantum algorithms it becomes increasingly important to provide precise bit-security estimates for code-based cryptography such as McEliece and quasi-cyclic schemes like BIKE and HQC. While there has been significant progress on information set decoding (ISD) algorithms within the last decade, it is still unclear to which extent this affects current cryptographic security estimates. We provide the first concrete implementations for representation-based ISD, such as May-Meurer-Thomae (MMT) or Becker-Joux-May-Meurer (BJMM), that are parameter-optimized for the McEliece and quasi-cyclic setting. Although MMT and BJMM consume more memory than naive ISD algorithms like Prange, we demonstrate that these algorithms lead to significant speedups for practical cryptanalysis on medium-sized instances (around 60 bit). More concretely, we provide data for the record computations of McEliece-1223 and McEliece-1284 (old record: 1161), and for the quasi-cyclic setting up to code length 2918 (before: 1938). Based on our record computations we extrapolate to the bit-security level of the proposed BIKE, HQC and McEliece parameters in NIST\u27s standardization process. For BIKE/HQC, we also show how to transfer the Decoding-One-Out-of-Many (DOOM) technique to MMT/BJMM. Although we achieve significant DOOM speedups, our estimates confirm the bit-security levels of BIKE and HQC. For the proposed McEliece round-3 parameter sets of 192 and 256 bit, however, our extrapolation indicates a security level overestimate by roughly 20 and 10 bits, respectively, i.e., the high-security McEliece instantiations may be a bit less secure than desired

A Non-Canonical E-Box Within the \u3cem\u3eMyoD\u3c/em\u3e Core Enhancer is Necessary for Circadian Expression in Skeletal Muscle

The myogenic differentiation 1 (MyoD) gene is a master regulator of myogenesis. We previously reported that the expression of MyoD mRNA oscillates over 24 h in skeletal muscle and that the circadian clock transcription factors, BMAL1 (brain and muscle ARNT-like 1) and CLOCK (circadian locomotor output cycles kaput), were bound to the core enhancer (CE) of the MyoD gene in vivo. In this study, we provide in vivo and in vitro evidence that the CE is necessary for circadian expression of MyoD in adult muscle. Gel shift assays identified a conserved non-canonical E-box within the CE that is bound by CLOCK and BMAL1. Functional analysis revealed that this E-box was required for full activation by BMAL1/CLOCK and for in vitro circadian oscillation. Expression profiling of muscle of CEloxP/loxP mice found approximately 1300 genes mis-expressed relative to wild-type. Based on the informatics results, we analyzed the respiratory function of mitochondria isolated from wild-type and CEloxP/loxP mice. These assays determined that State 5 respiration was significantly reduced in CEloxP/loxP muscle. The results of this work identify a novel element in the MyoD enhancer that confers circadian regulation to MyoD in skeletal muscle and suggest that loss of circadian regulation leads to changes in myogenic expression and downstream mitochondrial function

Optical properties of In2O3 from experiment and first-principles theory: influence of lattice screening

The framework of many-body perturbation theory led to deep insight into electronic structure and optical properties of diverse systems and, in particular, many semiconductors. It relies on an accurate approximation of the screened Coulomb electron–electron interaction W, that in current implementations is usually achieved by describing electronic interband transitions. However, our results for several oxide semiconductors indicate that for polar materials it is necessary to also account for lattice contributions to dielectric screening. To clarify this question in this work, we combine highly accurate experimentation and cutting-edge theoretical spectroscopy to elucidate the interplay of quasiparticle and excitonic effects for cubic bixbyite In2O3 across an unprecedentedly large photon energy range. We then show that the agreement between experiment and theory is excellent and, thus, validate that the physics of quasiparticle and excitonic effects is described accurately by these first-principles techniques, except for the immediate vicinity of the absorption onset. Finally, our combination of experimental and computational data clearly establishes the need for including a lattice contribution to dielectric screening in the screened electron–electron interaction, in order to improve the description of excitonic effects near the absorption edge