1,961 research outputs found
On the Kernel of -Linear Hadamard Codes
The -additive codes are subgroups of ,
and can be seen as a generalization of linear codes over and
. A -linear Hadamard code is a binary Hadamard
code which is the Gray map image of a -additive code. It is
known that the dimension of the kernel can be used to give a complete
classification of the -linear Hadamard codes. In this paper, the
kernel of -linear Hadamard codes and its dimension are
established for . Moreover, we prove that this invariant only provides a
complete classification for some values of and . The exact amount of
nonequivalent such codes are given up to for any , by using
also the rank and, in some cases, further computations
The Evolution of X-ray Clusters of Galaxies
Considerable progress has been made over the last decade in the study of the
evolutionary trends of the population of galaxy clusters in the Universe. In
this review we focus on observations in the X-ray band. X-ray surveys with the
ROSAT satellite, supplemented by follow-up studies with ASCA and Beppo-SAX,
have allowed an assessment of the evolution of the space density of clusters
out to z~1, and the evolution of the physical properties of the intra-cluster
medium out to z~0.5. With the advent of Chandra and Newton-XMM, and their
unprecedented sensitivity and angular resolution, these studies have been
extended beyond redshift unity and have revealed the complexity of the
thermodynamical structure of clusters. The properties of the intra-cluster gas
are significantly affected by non-gravitational processes including star
formation and Active Galactic Nucleus (AGN) activity. Convincing evidence has
emerged for modest evolution of both the bulk of the X-ray cluster population
and their thermodynamical properties since redshift unity. Such an
observational scenario is consistent with hierarchical models of structure
formation in a flat low density universe with Omega_m=0.3 and sigma_8=0.7-0.8
for the normalization of the power spectrum. Basic methodologies for
construction of X-ray-selected cluster samples are reviewed and implications of
cluster evolution for cosmological models are discussed.Comment: 40 pages, 15 figures. Full resolution figures can be downloaded from
http://www.eso.org/~prosati/ARAA
Signatures in Shape Analysis: an Efficient Approach to Motion Identification
Signatures provide a succinct description of certain features of paths in a
reparametrization invariant way. We propose a method for classifying shapes
based on signatures, and compare it to current approaches based on the SRV
transform and dynamic programming.Comment: 7 pages, 3 figures. Conference paper for Geometric Science of
Information 201
Cycling Rate-Induced Spatially-Resolved Heterogeneities in Commercial Cylindrical Li-Ion Batteries
Synchrotron high-energy X-ray diffraction computed tomography has been employed to investigate, for the first time, commercial cylindrical Li-ion batteries electrochemically cycled over the two cycling rates of C/2 and C/20. This technique yields maps of the crystalline components and chemical species as a cross-section of the cell with high spatiotemporal resolution (550 × 550 images with 20 × 20 × 3 µm3 voxel size in ca. 1 h). The recently developed Direct Least-Squares Reconstruction algorithm is used to overcome the well-known parallax problem and led to accurate lattice parameter maps for the device cathode. Chemical heterogeneities are revealed at both electrodes and are attributed to uneven Li and current distributions in the cells. It is shown that this technique has the potential to become an invaluable diagnostic tool for real-world commercial batteries and for their characterization under operating conditions, leading to unique insights into “real” battery degradation mechanisms as they occur
Coupling of alpha(1)-Adrenoceptors to ERK1/2 in the Human Prostate
Introduction: alpha(1)-Adrenoceptors are considered critical for the regulation of prostatic smooth muscle tone. However, previous studies suggested further alpha(1)-adrenoceptor functions besides contraction. Here, we investigated whether alpha(1)-adrenoceptors in the human prostate may activate extracellular signal-regulated kinases (ERK1/2). Methods: Prostate tissues from patients undergoing radical prostatectomy were stimulated in vitro. Activation of ERK1/2 was assessed by Western blot analysis. Expression of ERK1/2 was studied by immunohistochemistry. The effect of ERK1/2 inhibition by U0126 on phenylephrine-induced contraction was studied in organ-bath experiments. Results: Stimulation of human prostate tissue with noradrenaline (30 mu M) or phenylephrine (10 mu M) resulted in ERK activation. This was reflected by increased levels of phosphorylated ERK1/2. Expression of ERK1/2 in the prostate was observed in smooth muscle cells. Incubation of prostate tissue with U0126 (30 mu M) resulted in ERK1/2 inhibition. Dose-dependent phenylephrine-induced contraction of prostate tissue was not modulated by U0126. Conclusions: alpha(1)-Adrenoceptors in the human prostate are coupled to ERK1/2. This may partially explain previous observations suggesting a role of alpha(1)-adrenoceptors in the regulation of prostate growth. Copyright (C) 2011 S. Karger AG, Base
Simulations of events for the LUX-ZEPLIN (LZ) dark matter experiment
The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1–2)×10−12 pb at a WIMP mass of 40 GeV/c2. This paper describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data
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Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment
LUX-ZEPLIN (LZ) is a next-generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with weakly interacting massive particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000 live day run using a 5.6-tonne fiducial mass, LZ is projected to exclude at 90% confidence level spin-independent WIMP-nucleon cross sections above 1.4×10-48 cm2 for a 40 GeV/c2 mass WIMP. Additionally, a 5σ discovery potential is projected, reaching cross sections below the exclusion limits of recent experiments. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of 2.3×10-43 cm2 (7.1×10-42 cm2) for a 40 GeV/c2 mass WIMP is expected. With underground installation well underway, LZ is on track for commissioning at SURF in 2020
Soft tissue damage after minimally invasive THA: A comparison of 5 approaches
Methods 5 surgeons each performed a total hip arthroplasty on 5 fresh frozen cadaver hips, using either a MIS anterior, MIS anterolateral, MIS 2-incision, MIS posterior, or lateral transgluteal approach. Postoperatively, the hips were dissected and muscle damage color-stained. We measured proportional muscle damage relative to the midsubstance cross-sectional surface area (MCSA) using computerized color detection. The integrity of external rotator muscles, nerves, and ligaments was assessed by direct observation. Results None of the other MIS approaches resulted in less gluteus medius muscle damage than the lateral transgluteal approach. However, the MIS anterior approach completely preserved the gluteus medius muscle in 4 cases while partial damage occurred in 1 case. Furthermore, the superior gluteal nerve was transected in 4 cases after a MIS anterolateral approach and in 1 after the lateral transgluteal approach. The lateral femoral cutaneous nerve was transected once after both the MIS anterior approach and the MIS 2-incision approach. Interpretation The MIS anterior approach may preserve the gluteus medius muscle during total hip arthroplasty, but with a risk of damaging the lateral femoral cutaneous nerv
Analytic philosophy for biomedical research: the imperative of applying yesterday's timeless messages to today's impasses
The mantra that "the best way to predict the future is to invent it" (attributed to the computer scientist Alan Kay) exemplifies some of the expectations from the technical and innovative sides of biomedical research at present. However, for technical advancements to make real impacts both on patient health and genuine scientific understanding, quite a number of lingering challenges facing the entire spectrum from protein biology all the way to randomized controlled trials should start to be overcome. The proposal in this chapter is that philosophy is essential in this process. By reviewing select examples from the history of science and philosophy, disciplines which were indistinguishable until the mid-nineteenth century, I argue that progress toward the many impasses in biomedicine can be achieved by emphasizing theoretical work (in the true sense of the word 'theory') as a vital foundation for experimental biology. Furthermore, a philosophical biology program that could provide a framework for theoretical investigations is outlined
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