Study of the mapping of Navier-Stokes algorithms onto multiple-instruction/multiple-data-stream computers

Implicit approximate-factored algorithms have certain properties that are suitable for parallel processing. A particular computational fluid dynamics (CFD) code, using this algorithm, is mapped onto a multiple-instruction/multiple-data-stream (MIMD) computer architecture. An explanation of this mapping procedure is presented, as well as some of the difficulties encountered when trying to run the code concurrently. Timing results are given for runs on the Ames Research Center's MIMD test facility which consists of two VAX 11/780's with a common MA780 multi-ported memory. Speedups exceeding 1.9 for characteristic CFD runs were indicated by the timing results

Training Induced Positive Exchange Bias in NiFe/IrMn Bilayers

Positive exchange bias has been observed in the Ni$_{81}$Fe$_{19}$/Ir$_{20}$Mn$_{80}$ bilayer system via soft x-ray resonant magnetic scattering. After field cooling of the system through the blocking temperature of the antiferromagnet, an initial conventional negative exchange bias is removed after training i. e. successive magnetization reversals, resulting in a positive exchange bias for a temperature range down to 30 K below the blocking temperature (450 K). This new manifestation of magnetic training is discussed in terms of metastable magnetic disorder at the magnetically frustrated interface during magnetization reversal.Comment: 4 pages, 3 figure

Dual Behavior of Antiferromagnetic Uncompensated Spins in NiFe/IrMn Exchange Biased Bilayers

We present a comprehensive study of the exchange bias effect in a model system. Through numerical analysis of the exchange bias and coercive fields as a function of the antiferromagnetic layer thickness we deduce the absolute value of the averaged anisotropy constant of the antiferromagnet. We show that the anisotropy of IrMn exhibits a finite size effect as a function of thickness. The interfacial spin disorder involved in the data analysis is further supported by the observation of the dual behavior of the interfacial uncompensated spins. Utilizing soft x-ray resonant magnetic reflectometry we have observed that the antiferromagnetic uncompensated spins are dominantly frozen with nearly no rotating spins due to the chemical intermixing, which correlates to the inferred mechanism for the exchange bias.Comment: 4 pages, 3 figure

Probing the Catalytic Activity of a Cell Division-Specific Transpeptidase In Vivo with ß-Lactams

Penicillin-binding protein 3 (PBP3; also called FtsI) is a transpeptidase that catalyzes cross-linking of the peptidoglycan cell wall in the division septum of Escherichia coli. To determine whether the catalytic activity of PBP3 is activated during division, we assayed acylation of PBP3 with three ß-lactams (cephalexin, aztreonam, and piperacillin) in growing cells. Acylation of PBP3 with cephalexin, but not aztreonam or piperacillin, appeared to be stimulated by cell division. Specifically, cephalexin acylated PBP3 about 50% faster in a population of dividing cells than in a population of filamentous cells in which division was inhibited by inactivation or depletion of FtsZ, FtsA, FtsQ, FtsW, or FtsN. However, in a simpler in vitro system using isolated membranes, acylation with cephalexin was not impaired by depletion of FtsW or FtsN. A conflicting previous report that the ftsA3(Ts) allele interferes with acylation of PBP3 was found to be due to the presence of a thermolabile PBP3 in the strain used in that study. The new findings presented here are discussed in light of the hypothesis that the catalytic activity of PBP3 is stimulated by interaction(s) with other division proteins. We suggest that there might be allosteric activation of substrate bindin

Size-dependent Auger spectra and two-hole Coulomb interaction of small supported Cu-clusters

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Auger (L3M4,5M4,5) and X-ray photoionization spectra (2p, 3d) of mass-selected CuN-clusters supported by a thin natural silica layer are presented in the size range N = 8–55 atoms per cluster. The Auger spectra of all clusters are shifted to a lower kinetic energy with respect to the spectrum of the bulk. Furthermore the Auger energy decreases systematically with decreasing cluster size. The binding energies of the 2p and 3d valence states are higher than the corresponding bulk values. Using the energy of the Auger main line, the corresponding core hole peak and the centroid of the self-convoluted 3d valence band the on-site Coulomb interaction energy Udd of the two-hole final state as a function of cluster size has been determined

Особенности реализации режимов пониженного энергопотребления при внедрении распределенной системы управления теплопотреблением здания

An integrated model, consisting of a distributed automatic control system, building heating system and individual heating unit is designed. The model is based on the Simulink application. The conducted research allowed to reveal features of heating system operation with distributed control system. The results of comparison the climatic variables of control rooms are presented. The conclusions about the possibility of increasing the energy efficiency of heating system in the implementation of distributed control systems are presented

Control of Risk Factors Among People With Diagnosed Diabetes, by Lower Extremity Disease Status

Introduction We examined the control of modifiable risk factors among a national sample of diabetic people with and without lower extremity disease (LED). Methods The sample from the 1999-2004 National Health and Nutrition Examination Survey consisted of 948 adults aged 40 years or older with diagnosed diabetes and who had been assessed for LED. LED was defined as peripheral arterial disease (ankle-brachial index <0.9), peripheral neuropathy (≥1 insensate area), or presence of foot ulcer. Good control of modifiable risk factors, based on American Diabetes Association recommendations, included being a nonsmoker and having the following measurements: hemoglobin A1c (HbA1c) less than 7%, systolic blood pressure less than or equal to 130 mm Hg, diastolic blood pressure less than or equal to 80 mm Hg, high-density lipoprotein (HDL) cholesterol greater than 50 mg/dL, and body mass index (BMI) between 18.5 kg/m2 and 24.9 kg/m2. Results Diabetic people with LED were less likely than were people without LED to have recommended levels of HbA1c (39.3% vs 53.5%) and HDL cholesterol (29.7% vs 41.1%), but there were no differences in systolic or diastolic blood pressure, BMI classification, or smoking status between people with and without LED. Control of some risk factors differed among population subgroups. Notably, among diabetic people with LED, non-Hispanic blacks were more likely to have improper control of HbA1c (adjusted odds ratio [AOR] = 2.0; 95% confidence interval [CI], 1.1-3.9), systolic blood pressure (AOR = 1.9; 95% CI, 1.1-3.2), and diastolic blood pressure (AOR = 2.6; 95% CI, 1.1-5.8), compared with non-Hispanic whites. Conclusion Control of 2 of 6 modifiable risk factors was worse in diabetic adults with LED compared with diabetic adults without LED. Among diabetic people with LED, non-Hispanic blacks had worse control of 3 of 6 risk factors compared with non-Hispanic whites

Ultrafast relaxation dynamics of optically excited electrons in Ni3-

Photon-induced ultrafast energy dissipation in small isolated Ni-3(-) has been studied by two-color pump-probe photoelectron spectroscopy. The time-resolved photoelectron spectra clearly trace the path from a single-electron excitation to a thermalized cluster via both inelastic electron-electron scattering and electron-vibrational coupling. The relatively short electron-electron-scattering time of 215 fs results from the narrow energy spread of the partially filled d levels in this transition-metal cluster. The relaxation dynamics is discussed in view of the cluster size and in comparison to the totally different relaxation behavior of s/p-metal clusters

Micro-fluorescene lifetime and spectral imaging of ytterbium doped laser materials

We present the application of a confocal fluorescence microscope to the analysis of Yb-doped solid-state laser materials, with examples of Yb-doped crystals, photonic crystal fibers and fiber preforms made with different manufacturing processes. Beside the fluorescence lifetime image itself, a microscopic spectral fluorescence emission analysis is presented and spatially resolved emission cross sections are obtained. Doping concentration and its distributions and other laser optical parameters are measured, which help to analyze manufacturing steps. Further properties like photodarkening and saturation are addressed

On Binary Matroid Minors and Applications to Data Storage over Small Fields

Locally repairable codes for distributed storage systems have gained a lot of interest recently, and various constructions can be found in the literature. However, most of the constructions result in either large field sizes and hence too high computational complexity for practical implementation, or in low rates translating into waste of the available storage space. In this paper we address this issue by developing theory towards code existence and design over a given field. This is done via exploiting recently established connections between linear locally repairable codes and matroids, and using matroid-theoretic characterisations of linearity over small fields. In particular, nonexistence can be shown by finding certain forbidden uniform minors within the lattice of cyclic flats. It is shown that the lattice of cyclic flats of binary matroids have additional structure that significantly restricts the possible locality properties of $\mathbb{F}_{2}$-linear storage codes. Moreover, a collection of criteria for detecting uniform minors from the lattice of cyclic flats of a given matroid is given, which is interesting in its own right.Comment: 14 pages, 2 figure