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Search Results: 1 - 10 of 53750 matches for " Thomas Vizhalil Paul "
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Osteoporosis in Healthy South Indian Males and the Influence of Life Style Factors and Vitamin D Status on Bone Mineral Density
Sahana Shetty,Nitin Kapoor,Dukhabandhu Naik,Hesarghatta Shyamasunder Asha,Suresh Prabu,Nihal Thomas,Mandalam Subramaniam Seshadri,Thomas Vizhalil Paul
Journal of Osteoporosis , 2014, DOI: 10.1155/2014/723238
Abstract: Objective. To study the prevalence of osteoporosis and vitamin D deficiency in healthy men and to explore the influence of various life style factors on bone mineral density (BMD) and also to look at number of subjects warranting treatment. Methods. Ambulatory south Indian men aged above 50 were recruited by cluster random sampling. The physical activity, risk factors in the FRAX tool, BMD, vitamin D, and PTH were assessed. The number of people needing treatment was calculated, which included subjects with osteoporosis and osteopenia with 10-year probability of major osteoporotic fracture >20 percent and hip fracture >3 percent in FRAX India. Results. A total of 252 men with a mean age of 58 years were studied. The prevalence of osteoporosis and osteopenia at any one site was 20% (50/252) and 58%, respectively. Vitamin D deficiency (<20?ng/dL) was seen in 53%. On multiple logistic regression, BMI (OR 0.3; value = 0.04) and physical activity (OR 0.4; value < 0.001) had protective effect on BMD. Twenty-five percent warranted treatment. Conclusions. A significantly large proportion of south Indian men had osteoporosis and vitamin D deficiency. Further interventional studies are needed to look at reduction in end points like fractures in these subjects. 1. Introduction Osteoporosis in men is now recognized as a major underestimated public health problem [1]. With the gradual increase in life expectancy, advancing age related illnesses are increasing [2]. After the age of fifty, one out of three osteoporotic fractures are seen in men. Furthermore, an in depth understanding of this subject has revealed that about fifty percent of these causes are potentially treatable. Studies have shown that men with osteoporotic fractures have a much higher mortality and morbidity when compared to women [3]. This may add on to the economic burden in a developing country like India, where men may be the only earning members in many families [4]. In addition to genetic determinants, several life-style related factors like physical activity, calcium intake, smoking, alcohol consumption, and vitamin D status may influence the bone mass in men [5]. However, the prevalence and influence of these factors may vary according to ethnicity. Screening for osteoporosis in men is usually recommended above the age of 70 years [1, 5]. However, its relevance in relation to the variability in ethnicity requires validation through prospective studies. There are differences in peak bone mass, body frame, and nutrition and life style factors among various populations [1]. There are no clear
Forwarding vs. Network Coding: Efficient Broadcasting in Multihop Wireless Networks  [PDF]
Suranjit Paul, Thomas Kunz, Li Li
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.44025
Abstract: Broadcasting is used as a building block in many MANET (Mobile Ad hoc Network) routing protocols. In addition, broadcasting is a key primitive in ad hoc networks to support group-based applications. Efficiently supporting broadcasting in multihop wireless networks is therefore important. In this paper, we compare ef-ficient broadcasting protocols based on packet forwarding with those based on network coding. Using a number of network scenarios, we derive lower bounds for the required number of packet retransmissions at the MAC layer to support broadcast with and without applying network coding techniques. We compare these lower bounds with each other, as well as with protocols proposed for each approach. More specifically, we use SMF and PDP as sample forwarding-based broadcast protocols, and a simple XOR-based coding protocol over SMF and PDP as representative network coding solution. The results show that neither packet forwarding protocols nor network coding protocols achieve the theoretical lower bounds, in particular as the size of the network area (at constant density) increases. The comparison of the lower bounds also shows that network coding does have a potential performance advantage over packet forwarding solutions for broad-casting in multi-hop wireless networks, in particular for larger fixed density networks, justifying its inherent increased complexity.
GIGA: a simple, efficient algorithm for gene tree inference in the genomic age
Paul D Thomas
BMC Bioinformatics , 2010, DOI: 10.1186/1471-2105-11-312
Abstract: We describe a simple, fast algorithm for inferring gene phylogenies, which makes use of information that was not available prior to the genomic age: namely, a reliable species tree spanning much of the tree of life, and knowledge of the complete complement of genes in a species' genome. The algorithm, called GIGA, constructs trees agglomeratively from a distance matrix representation of sequences, using simple rules to incorporate this genomic age information. GIGA makes use of a novel conceptualization of gene trees as being composed of orthologous subtrees (containing only speciation events), which are joined by other evolutionary events such as gene duplication or horizontal gene transfer. An important innovation in GIGA is that, at every step in the agglomeration process, the tree is interpreted/reinterpreted in terms of the evolutionary events that created it. Remarkably, GIGA performs well even when using a very simple distance metric (pairwise sequence differences) and no distance averaging over clades during the tree construction process.GIGA is efficient, allowing phylogenetic reconstruction of very large gene families and determination of orthologs on a large scale. It is exceptionally robust to adding more gene sequences, opening up the possibility of creating stable identifiers for referring to not only extant genes, but also their common ancestors. We compared trees produced by GIGA to those in the TreeFam database, and they were very similar in general, with most differences likely due to poor alignment quality. However, some remaining differences are algorithmic, and can be explained by the fact that GIGA tends to put a larger emphasis on minimizing gene duplication and deletion events.Phylogenetic inference algorithms have a very long history [1]. The earliest algorithms used information about macroscopic phenotypic "characters" to determine the evolutionary relationships between species. So it was natural that as soon as genetic (DNA) or genetically
Late presentation of sorafenib-associated rash: a case report
Thomas Sarkodie, Paul Ross
Journal of Medical Case Reports , 2010, DOI: 10.1186/1752-1947-4-338
Abstract: A 75-year-old Caucasian man initially presented with asymptomatic transient jaundice. He was diagnosed with Barcelona Clinic Liver Cancer stage B hepatocellular carcinoma after extensive investigation. He tolerated sorafenib 400 mg twice a day before presenting nine months later with a rash, confirmed to be drug-induced.Sorafenib is a drug of choice in Barcelona Clinic Liver Cancer stage B hepatocellular carcinoma. It can cause protracted rash quite late into treatment. Successful management of the rash could contribute to achieving stable disease in hepatocellular carcinoma over a significant period of time.Hepatocellular carcinoma (HCC) is the fifth most common neoplasm in the world and the third most frequent cause of cancer death worldwide [1]. The incidence of HCC is 500,000 to one million cases per year.HCC is closely associated with hepatic cirrhosis in the western world, being found in about 70% of all cases. Treatment of HCC is effective in improving survival only when diagnosed at an early stage of the disease.Tumor staging at diagnosis is essential in deciding appropriate treatment. The most recognized staging systems for HCC currently include the (i) Okuda staging system, (ii) Cancer of the Liver Italian Program (CLIP) scoring system and the (iii) Barcelona Clinic Liver Cancer (BCLC) staging (Tables 1 and 2) [2].Using the BCLC staging stage A can be managed with radical therapies, such as resection, transplantation or percutaneous treatments. Stages B and C are managed with new agents in clinical trials or palliative care. Transarterial chemoembolization (TACE) is beneficial but is limited by patient suitability and maximum dose of chemotherapy agent used [3,4]. Stage D is for symptomatic treatment [5].Sorafenib is an oral multitargeted tyrosine kinase inhibitor. It inhibits the receptor tyrosine receptors (RTKs), VEGFR 1-3 (vascular endothelial growth factor receptor), FLT-3 (fms-like tyrosine kinase receptor-3), PDGFR (platelet-derived growth factor re
Physics, chemistry and biology of functional nanostructures
Paul Ziemann,Thomas Schimmel
Beilstein Journal of Nanotechnology , 2012, DOI: 10.3762/bjnano.3.94
What automated analyses of corpora can tell us about students’ writing skills
Paul Deane,Thomas Quinlan
Journal of Writing Research , 2010,
Abstract: A particular application of corpus analysis, automated essay scoring (AES) can reveal much about students’ writing skills. In this article we present research undertaken at Educational Testing Service (ETS) as part of its ongoing commitment to developing effective AES systems. AES systems have certain advantages. They can: (a) produce scores similar to those assigned trained human raters, (b) provide a single consistent metric for scoring, and (c) automate linguistic analyses. However, to understand student writing, we may need to look beyond the final essay in various ways, to consider both the process and the product. By broadening our definition of corpora, to capture the dynamics of written composition, it may become possible to identify profiles of writing behavior.
On the Backreaction of Scalar and Spinor Quantum Fields in Curved Spacetimes - From the Basic Foundations to Cosmological Applications
Thomas-Paul Hack
Physics , 2010,
Abstract: First, the present work is concerned with generalising constructions and results in quantum field theory on curved spacetimes from the well-known case of the Klein-Gordon field to Dirac fields. To this end, the enlarged algebra of observables of the Dirac field is constructed in the algebraic framework. This algebra contains normal-ordered Wick polynomials in particular, and an extended analysis of one of its elements, the stress-energy tensor, is performed. Based on detailed calculations of the Hadamard coefficients of the Dirac field, it is found that a construction of a stress-energy tensor fulfilling necessary physical properties is possible. Additionally, the mathematically sound Hadamard regularisation prescription of the stress-energy tensor is compared to the mathematically less rigorous DeWitt-Schwinger regularisation and it is found that both prescriptions are essentially equivalent in rigorous terms. While the aforementioned results hold in generic curved spacetimes, particular attention is also devoted to a specific class of Robertson-Walker spacetimes with a lightlike Big Bang hypersurface. Employing holographic methods, Hadamard states for the Klein-Gordon and the Dirac field are constructed. These states are preferred in the sense that they constitute asymptotic equilibrium states in the limit to the Big Bang hypersurface. Finally, solutions of the semiclassical Einstein equation for quantum fields of arbitrary spin are analysed in the flat Robertson-Walker case. One finds that these solutions explain the measured supernova Ia data as good as the $\La$CDM model. Hence, one arrives at a natural explanation of dark energy and a simple quantum model of cosmological dark matter. It is the hope of the author that the present thesis can serve as an accessible introduction to the field of (algebraic) quantum field theory on curved spacetimes and its recent developments.
Cosmological Applications of Algebraic Quantum Field Theory in Curved Spacetimes
Thomas-Paul Hack
Physics , 2015,
Abstract: This monograph provides a largely self--contained and broadly accessible exposition of two cosmological applications of algebraic quantum field theory (QFT) in curved spacetime: a fundamental analysis of the cosmological evolution according to the Standard Model of Cosmology and a fundamental study of the perturbations in Inflation. The two central sections of the book dealing with these applications are preceded by sections containing a pedagogical introduction to the subject as well as introductory material on the construction of linear QFTs on general curved spacetimes with and without gauge symmetry in the algebraic approach, physically meaningful quantum states on general curved spacetimes, and the backreaction of quantum fields in curved spacetimes via the semiclassical Einstein equation. The target reader should have a basic understanding of General Relativity and QFT on Minkowski spacetime, but does not need to have a background in QFT on curved spacetimes or the algebraic approach to QFT. In particular, I took a great deal of care to provide a thorough motivation for all concepts of algebraic QFT touched upon in this monograph, as they partly may seem rather abstract at first glance. Thus, it is my hope that this work can help non--experts to make `first contact' with the algebraic approach to QFT.
Quantization of the linearised Einstein-Klein-Gordon system on arbitrary backgrounds and the special case of perturbations in Inflation
Thomas-Paul Hack
Physics , 2014, DOI: 10.1088/0264-9381/31/21/215004
Abstract: We quantize the linearised Einstein-Klein-Gordon system on arbitrary on-shell backgrounds in a manifestly covariant and gauge-invariant manner. For the special case of perturbations in Inflation, i.e. on-shell backgrounds of Friedmann-Lema\^itre-Robertson-Walker type, we compare our general quantization construction with the standard approach to the quantum theory of perturbations in Inflation. We find that not all local quantum observables of the linearised Einstein-Klein-Gordon system can be split into local observables of scalar and tensor type as in the standard approach. However, we argue that this subclass of observables is sufficient for measuring perturbations which vanish at spatial infinity, which is in line with standard assumptions. Finally, we comment on a recent observation that, upon standard quantization, the quantum Bardeen potentials display a non-local behaviour and argue that a similar phenomenon occurs in any local quantum field theory.
The Lambda CDM-model in quantum field theory on curved spacetime and Dark Radiation
Thomas-Paul Hack
Physics , 2013,
Abstract: In the standard model of cosmology, the universe is described by a Robertson-Walker spacetime, while its matter/energy content is modeled by a perfect fluid with three components corresponding to matter/dust, radiation and a cosmological constant. On the other hand, in particle physics matter and radiation are described in terms of quantum field theory on Minkowski spacetime. We unify these seemingly different theoretical frameworks by analysing the standard model of cosmology from first principles within quantum field theory on curved spacetime: assuming that the universe is homogeneous and isotropic on large scales, we specify a class of quantum states whose expectation value of the energy density is qualitatively and quantitatively of the standard perfect fluid form up to potential corrections. Qualitatively, these corrections depend on new parameters not present in the standard Lambda CDM-model and can account for e.g. the phenomenon of Dark Radiation (N_eff>3.046), having a characteristic signature which clearly deviates from other potential Dark Radiation sources such as e.g. sterile neutrinos. Quantitatively, we find that our more fundamental model can be perfectly matched to observational data, such that we arrive at a natural and fundamental extension of the Lambda CDM-model.
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