695 research outputs found
Chromoelectric fields and quarkonium-hadron interactions at high energies
We develop a simple model to study the heavy quarkonium-hadron cross section
in the high energy limit. The hadron is represented by an external electric
color field (capacitor) and the heavy quarkonium is represented by a small
color dipole. Using high energy approximations we compute the relevant cross
sections, which are then compared with results obtained with other methods. Our
calculations are presented in a pedagogical way accessible to undergraduate
students.Comment: To appear in Physical Review C, 24 pages, 10 eps figure
The Association between Urban Form and Ischemic Heart Disease: Evidence from Brisbane, Australia
We measured the association between urban form and hospitalisation rates for Ischemic Heart Disease (IHD), stratified by age and sex, and controlling for ethnicity, socio economic status, proximity to hospital and neighbourhood walk ability. This was a retrospective cohort study of the proportion of people within the Brisbane area of Australia who were hospitalised between 2006 to 2011 with a primary diagnosis of IHD. There were strong spatial patterns in the incidence of IHD. The importance of predictor variables differed by sex and age. Urban form was generally not a strong predictor. This study suggests no strong relationship was identified between urban form factors and ischemic heart disease using this research approach
Genome-Wide Association Study in Mexican Holstein Cattle Reveals Novel Quantitative Trait Loci Regions and Confirms Mapped Loci for Resistance to Bovine Tuberculosis
Bovine tuberculosis (bTB) is a disease of cattle that represents a risk to public health and causes severe economic losses to the livestock industry. Recently, genetic studies, like genome-wide association studies (GWAS) have greatly improved the investigation of complex diseases identifying thousands of disease-associated genomic variants. Here, we present evidence of genetic variants associated with resistance to TB in Mexican dairy cattle using a case-control approach with a selective DNA pooling experimental design. A total of 154 QTLRs (quantitative trait loci regions) at 10% PFP (proportion of false positives), 42 at 5% PFP and 5 at 1% PFP have been identified, which harbored 172 annotated genes. On BTA13, five new QTLRs were identified in the MACROD2 and KIF16B genes, supporting their involvement in resistance to bTB. Six QTLRs harbor seven annotated genes that have been previously reported as involved in immune response against Mycobacterium spp: BTA (Bos taurus autosome) 1 (CD80), BTA3 (CTSS), BTA 3 (FCGR1A), BTA 23 (HFE), BTA 25 (IL21R), and BTA 29 (ANO9 and SIGIRR). We identified novel QTLRs harboring genes involved in Mycobacterium spp. immune response. This is a first screening for resistance to TB infection on Mexican dairy cattle based on a dense SNP (Single Nucleotide Polymorphism) chip
Advanced Magnetic Resonance Imaging and Molecular Imaging of the Painful Knee
Chronic knee pain is a common condition. Causes of knee pain include trauma, inflammation, and degeneration, but in many patients the pathophysiology remains unknown. Recent developments in advanced magnetic resonance imaging (MRI) techniques and molecular imaging facilitate more in-depth research focused on the pathophysiology of chronic musculoskeletal pain and more specifically inflammation. The forthcoming new insights can help develop better targeted treatment, and some imaging techniques may even serve as imaging biomarkers for predicting and assessing treatment response in the future. This review highlights the latest developments in perfusion MRI, diffusion MRI, and molecular imaging with positron emission tomography/MRI and their application in the painful knee. The primary focus is synovial inflammation, also known as synovitis. Bone perfusion and bone metabolism are also addressed.</p
Block Spin Density Matrix of the Inhomogeneous AKLT Model
We study the inhomogeneous generalization of a 1-dimensional AKLT spin chain
model. Spins at each lattice site could be different. Under certain conditions,
the ground state of this AKLT model is unique and is described by the
Valence-Bond-Solid (VBS) state. We calculate the density matrix of a contiguous
block of bulk spins in this ground state. The density matrix is independent of
spins outside the block. It is diagonalized and shown to be a projector onto a
subspace. We prove that for large block the density matrix behaves as the
identity in the subspace. The von Neumann entropy coincides with Renyi entropy
and is equal to the saturated value.Comment: 20 page
Advanced Magnetic Resonance Imaging and Molecular Imaging of the Painful Knee
Chronic knee pain is a common condition. Causes of knee pain include trauma, inflammation, and degeneration, but in many patients the pathophysiology remains unknown. Recent developments in advanced magnetic resonance imaging (MRI) techniques and molecular imaging facilitate more in-depth research focused on the pathophysiology of chronic musculoskeletal pain and more specifically inflammation. The forthcoming new insights can help develop better targeted treatment, and some imaging techniques may even serve as imaging biomarkers for predicting and assessing treatment response in the future. This review highlights the latest developments in perfusion MRI, diffusion MRI, and molecular imaging with positron emission tomography/MRI and their application in the painful knee. The primary focus is synovial inflammation, also known as synovitis. Bone perfusion and bone metabolism are also addressed.</p
Invasion of Africa by a single pfcrt allele of South East Asian type
BACKGROUND: Because of its dramatic public health impact, Plasmodium falciparum resistance to chloroquine (CQ) has been documented early on. Chloroquine-resistance (CQR) emerged in the late 1950's independently in South East Asia and South America and progressively spread over all malaria areas. CQR was reported in East Africa in the 1970's, and has since invaded the African continent. Many questions remain about the actual selection and spreading process of CQR parasites, and about the evolution of the ancestral mutant gene(s) during spreading. METHODS: Eleven clinical isolates of P. falciparum from Cambodia and 238 from Africa (Senegal, Ivory Coast, Bukina Faso, Mali, Guinea, Togo, Benin, Niger, Congo, Madagascar, Comoros Islands, Tanzania, Kenya, Mozambique, Cameroun, Gabon) were collected during active case detection surveys carried out between 1996 and 2001. Parasite DNA was extracted from frozen blood aliquots and amplification of the gene pfcrt exon 2 (codon 72–76), exon 4 and intron 4 (codon 220 and microsatellite marker) were performed. All fragments were sequenced. RESULTS: 124 isolates with a sensitive (c76/c220:CVMNK/A) haplotype and 125 isolates with a resistant c76/c220:CVIET/S haplotype were found. The microsatellite showed 17 different types in the isolates carrying the c76/c220:CVMNK/A haplotype while all 125 isolates with a CVIET/S haplotype but two had a single microsatellite type, namely (TAAA)3(TA)15, whatever the location or time of collection. CONCLUSION: Those results are consistent with the migration of a single ancestral pfcrt CQR allele from Asia to Africa. This is related to the importance of PFCRT in the fitness of P. falciparum point out this protein as a potential target for developments of new antimalarial drugs
Entanglement Sharing in the Two-Atom Tavis-Cummings Model
Individual members of an ensemble of identical systems coupled to a common
probe can become entangled with one another, even when they do not interact
directly. We investigate how this type of multipartite entanglement is
generated in the context of a system consisting of two two-level atoms
resonantly coupled to a single mode of the electromagnetic field. The dynamical
evolution is studied in terms of the entanglements in the different bipartite
partitions of the system, as quantified by the I-tangle. We also propose a
generalization of the so-called residual tangle that quantifies the inherent
three-body correlations in our tripartite system. This enables us to completely
characterize the phenomenon of entanglement sharing in the case of the two-atom
Tavis-Cummings model, a system of both theoretical and experimental interest.Comment: 11 pages, 4 figures, submitted to PRA, v3 contains corrections to
small error
Worker Characteristics and Wage Differentials: Evidence from a Gift-Exchange Experiment
There is ample empirical evidence indicating that a substantial fraction of the population exhibits social preferences. Recent work also shows that social preferences influence the effectiveness of incentives in labor relations. Hence when making contracting decisions, employers should take into account that workers are heterogenous with respect to both their productivity and their social preferences. This paper presents causal evidence that they do. In a real-effort experiment, we elicit measures of workers' productivity and trustworthiness and make this information available to potential employers. Our data show that employers pay significant wage premia for both traits. Firms make highest profits with trustworthy workers, in particular with highly productive and trustworthy workers. We also document differences in the strength of gift exchange across worker types. In particular, output and profit levels of trustworthy workers are less dispersed than those of not-trustworthy workers
Isokinetic strength of the trunk flexor muscles after surgical repair for incisional hernia
Purpose The repair of incisional hernias can be accomplished by open or laparoscopic techniques. The Biodex® dynamometer measures muscle strength during isokinetic movement. The objectives of this study are to compare the strength of the trunk Xexors between patients who underwent repair for incisional hernia and a control group, and to compare trunk Xexion after two kinds of operative techniques for incisional hernias with and without approximation of the rectus abdominis muscles. Methods The trunk Xexion of 30 patients after different operative techniques for midline incisional hernias and of 12 healthy subjects was studied with the Biodex® isokinetic dynamometer. Results The mean torque/weight (N m/kg) for trunk Xexion was significantly higher in the control group compared to the patient group after incisional hernia repair. A significantly higher peak torque/weight [coefficient 24.45, 95% confidence interval (CI) -0.05; 48.94, P = 0.05] was found in the two-layered suture technique without mesh compared to the laparoscopic technique after adjusting for gender. Conclusions The isokinetic strength of the trunk Xexor muscles is reduced after an operation for incisional hernia. There is some evidence that a two-layered suture repair with approximation of the rectus abdominis muscles results in higher isokinetic strength of the trunk Xexor muscles compared to the laparoscopic technique
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