Tomographic Image Reconstructing Using Systolic Array Alogrithms

In Computed Tomography (CT), two-dimensional (2-D) slices or three-imensional (3-D) volumes of an object are reconstructed from many projected line-integrals (usually x-ray transmission data) around the object. As the data collection capabilities and reconstruction algorithms for CT have become more sophisticated over the years, the demands on computer systems have become correspondingly greater. For example, cone-beam data acquisition of a single 2-D projection containing 1024 by 1024 resolution is now easily achievable in much less than 1 second. Accepting and processing a volume of data at those rates is impossible for most conventional computers. Also, recent limited-data reconstruction algorithms using iterative schemes between image and projection domains [1] require large amounts of very time-consuming calculations. In this case, repeated use of a constrained projection model (or the Radon transform, named after mathematician Johann Radon [2]) followed by a reconstruction algorithm (or inverse Radon transform) is used to converge on the correct answer.</p

Weinberg like sum rules revisited

The generalized Weinberg sum rules containing the difference of isovector vector and axial-vector spectral functions saturated by both finite and infinite number of narrow resonances are considered. We summarize the status of these sum rules and analyze their overall agreement with phenomenological Lagrangians, low-energy relations, parity doubling, hadron string models, and experimental data.Comment: 31 pages, noticed misprints are corrected, references are added, and other minor corrections are mad

X-Ray Spectroscopy of Stars

(abridged) Non-degenerate stars of essentially all spectral classes are soft X-ray sources. Low-mass stars on the cooler part of the main sequence and their pre-main sequence predecessors define the dominant stellar population in the galaxy by number. Their X-ray spectra are reminiscent, in the broadest sense, of X-ray spectra from the solar corona. X-ray emission from cool stars is indeed ascribed to magnetically trapped hot gas analogous to the solar coronal plasma. Coronal structure, its thermal stratification and geometric extent can be interpreted based on various spectral diagnostics. New features have been identified in pre-main sequence stars; some of these may be related to accretion shocks on the stellar surface, fluorescence on circumstellar disks due to X-ray irradiation, or shock heating in stellar outflows. Massive, hot stars clearly dominate the interaction with the galactic interstellar medium: they are the main sources of ionizing radiation, mechanical energy and chemical enrichment in galaxies. High-energy emission permits to probe some of the most important processes at work in these stars, and put constraints on their most peculiar feature: the stellar wind. Here, we review recent advances in our understanding of cool and hot stars through the study of X-ray spectra, in particular high-resolution spectra now available from XMM-Newton and Chandra. We address issues related to coronal structure, flares, the composition of coronal plasma, X-ray production in accretion streams and outflows, X-rays from single OB-type stars, massive binaries, magnetic hot objects and evolved WR stars.Comment: accepted for Astron. Astrophys. Rev., 98 journal pages, 30 figures (partly multiple); some corrections made after proof stag

Stellar Coronal and Wind Models: Impact on Exoplanets

Surface magnetism is believed to be the main driver of coronal heating and stellar wind acceleration. Coronae are believed to be formed by plasma confined in closed magnetic coronal loops of the stars, with winds mainly originating in open magnetic field line regions. In this Chapter, we review some basic properties of stellar coronae and winds and present some existing models. In the last part of this Chapter, we discuss the effects of coronal winds on exoplanets.Comment: Chapter published in the "Handbook of Exoplanets", Editors in Chief: Juan Antonio Belmonte and Hans Deeg, Section Editor: Nuccio Lanza. Springer Reference Work

A multi-stage genome-wide association study of bladder cancer identifies multiple susceptibility loci.

We conducted a multi-stage, genome-wide association study of bladder cancer with a primary scan of 591,637 SNPs in 3,532 affected individuals (cases) and 5,120 controls of European descent from five studies followed by a replication strategy, which included 8,382 cases and 48,275 controls from 16 studies. In a combined analysis, we identified three new regions associated with bladder cancer on chromosomes 22q13.1, 19q12 and 2q37.1: rs1014971, (P = 8 × 10⁻¹²) maps to a non-genic region of chromosome 22q13.1, rs8102137 (P = 2 × 10⁻¹¹) on 19q12 maps to CCNE1 and rs11892031 (P = 1 × 10⁻⁷) maps to the UGT1A cluster on 2q37.1. We confirmed four previously identified genome-wide associations on chromosomes 3q28, 4p16.3, 8q24.21 and 8q24.3, validated previous candidate associations for the GSTM1 deletion (P = 4 × 10⁻¹¹) and a tag SNP for NAT2 acetylation status (P = 4 × 10⁻¹¹), and found interactions with smoking in both regions. Our findings on common variants associated with bladder cancer risk should provide new insights into the mechanisms of carcinogenesis

Climate driven life histories: the case of the Mediterranean Storm petrel

Seabirds are affected by changes in the marine ecosystem. The influence of climatic factors on marine food webs can be reflected in long-term seabird population changes. We modelled the survival and recruitment of the Mediterranean storm petrel (Hydrobates pelagicus melitensis) using a 21-year mark-recapture dataset involving almost 5000 birds. We demonstrated a strong influence of prebreeding climatic conditions on recruitment age and of rainfall and breeding period conditions on juvenile survival. The results suggest that the juvenile survival rate of the Mediterranean subspecies may not be negatively affected by the predicted features of climate change, i.e., warmer summers and lower rainfall. Based on considerations of winter conditions in different parts of the Mediterranean, we were able to draw inferences about the wintering areas of the species for the first time

The Retinoic Acid Receptor Agonist Am80 Increases Mucosal Inflammation in an IL-6 Dependent Manner During Trichuris muris Infection

PURPOSE: Vitamin A metabolites, such as all-trans-retinoic acid (RA) that act through the nuclear receptor; retinoic acid receptor (RAR), have been shown to polarise T cells towards Th2, and to be important in resistance to helminth infections. Co-incidentally, people harbouring intestinal parasites are often supplemented with vitamin A, as both vitamin A deficiency and parasite infections often occur in the same regions of the globe. However, the impact of vitamin A supplementation on gut inflammation caused by intestinal parasites is not yet completely understood. METHODS: Here, we use Trichuris muris, a helminth parasite that buries into the large intestine of mice causing mucosal inflammation, as a model of both human Trichuriasis and IBD, treat with an RARα/β agonist (Am80) and quantify the ensuing pathological changes in the gut. RESULTS: Critically, we show, for the first time, that rather than playing an anti-inflammatory role, Am80 actually exacerbates helminth-driven inflammation, demonstrated by an increased colonic crypt length and a significant CD4(+) T cell infiltrate. Further, we established that the Am80-driven crypt hyperplasia and CD4(+) T cell infiltrate were dependent on IL-6, as both were absent in Am80-treated IL-6 knock-out mice. CONCLUSIONS: This study presents novel data showing a pro-inflammatory role of RAR ligands in T. muris infection, and implies an undesirable effect for the administration of vitamin A during chronic helminth infection. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10875-013-9936-8) contains supplementary material, which is available to authorized users