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Search Results: 1 - 10 of 12425 matches for " Gregory Alan Hand "
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Moderate-Intensity Exercise Improves Body Composition and Improves Physiological Markers of Stress in HIV-Infected Men
Wesley David Dudgeon,Jason Reed Jaggers,Kenneth Doyle Phillips,John Larry Durstine,Stephanie E. Burgess,George William Lyerly,John Mark Davis,Gregory Alan Hand
ISRN AIDS , 2012, DOI: 10.5402/2012/145127
Abstract: HIV/AIDS and its treatment often alter body composition and result in poorer physical functioning. The aim of this study was to determine the effects of a moderate-intensity exercise program on body composition and the hormones and cytokines associated with adverse health outcomes. HIV-infected males ( ) were randomized to an exercise group (EX) who completed 6 weeks of moderate-intensity exercise training, or to a nonintervention control group (CON). In pre- and postintervention, body composition was estimated via DXA, peak strength was assessed, and resting blood samples were obtained. There was a decrease in salivary cortisol at wake ( ) in the EX and a trend ( ) for a decrease 1 hour after waking. The EX had a significant increase in lean tissue mass (LTM) ( ) following the intervention. Those in the EX below median body fat (20%) increased LTM ( ) only, while those above 20% decreased fat mass ( ), total fat ( ), and trunk fat ( ), while also increasing LTM ( ). Peak strength increased between 14% and 28% on all exercises in the EX group. These data indicate that 6 weeks of moderate-intensity exercise training can decrease salivary cortisol levels, improve physical performance, and improve body composition in HIV-infected men. 1. Introduction Over 33.3 million people are living with HIV-1 [1]. Since it was introduced in the mid to late 1990s, highly active antiretroviral therapy (HAART) has increased the time from HIV infection to acquired immunodeficiency syndrome (AIDS) diagnosis by 3 years and life expectancy of those with AIDS by up to 15 years [2]. In fact, these advances have allowed those living with HIV-1, and receiving treatment, to have life expectancies similar to uninfected persons with lifestyles that include smoking, heavy drinking, and obesity [3]. Mortality rates of HIV-infected persons dropped drastically within 18 months after the introduction of HAART, from 29.4 deaths per 100 person years to 8.8 deaths per 100 person years [4]. In fact, in younger (~30 years of age) persons with favorable disease markers (i.e., high CD4+ cell counts and low viral load) survival has been estimated at 31 years, with 45% of deaths attributable to non-HIV-related conditions, such as cardiovascular disease and cancer [5]. This brings about new challenges in treating persons with HIV-1, changing the focus from purely survival to improving quality of life by decreasing risk factors for other chronic conditions. Thus, it is important to understand how exercise training, which has been shown to be beneficial at reducing risk factors for both
Validity of U.S. Nutritional Surveillance: National Health and Nutrition Examination Survey Caloric Energy Intake Data, 1971–2010
Edward Archer, Gregory A. Hand, Steven N. Blair
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076632
Abstract: Importance Methodological limitations compromise the validity of U.S. nutritional surveillance data and the empirical foundation for formulating dietary guidelines and public health policies. Objectives Evaluate the validity of the National Health and Nutrition Examination Survey (NHANES) caloric intake data throughout its history, and examine trends in the validity of caloric intake estimates as the NHANES dietary measurement protocols evolved. Design Validity of data from 28,993 men and 34,369 women, aged 20 to 74 years from NHANES I (1971–1974) through NHANES 2009–2010 was assessed by: calculating physiologically credible energy intake values as the ratio of reported energy intake (rEI) to estimated basal metabolic rate (BMR), and subtracting estimated total energy expenditure (TEE) from NHANES rEI to create ‘disparity values’. Main Outcome Measures 1) Physiologically credible values expressed as the ratio rEI/BMR and 2) disparity values (rEI–TEE). Results The historical rEI/BMR values for men and women were 1.31 and 1.19, (95% CI: 1.30–1.32 and 1.18–1.20), respectively. The historical disparity values for men and women were ?281 and ?365 kilocalorie-per-day, (95% CI: ?299, ?264 and ?378, ?351), respectively. These results are indicative of significant under-reporting. The greatest mean disparity values were ?716 kcal/day and ?856 kcal/day for obese (i.e., ≥30 kg/m2) men and women, respectively. Conclusions Across the 39-year history of the NHANES, EI data on the majority of respondents (67.3% of women and 58.7% of men) were not physiologically plausible. Improvements in measurement protocols after NHANES II led to small decreases in underreporting, artifactual increases in rEI, but only trivial increases in validity in subsequent surveys. The confluence of these results and other methodological limitations suggest that the ability to estimate population trends in caloric intake and generate empirically supported public policy relevant to diet-health relationships from U.S. nutritional surveillance is extremely limited.
Top 10 Research Questions Related to Energy Balance

Robin P. Shook,Gregory A. Hand,Steven N. Blair
- , 2015, DOI: 10.19582/j.cnki.11-3785/g8.2015.07.008
Abstract: 摘要:肥胖是较长时间段内热量摄入和消耗失衡导致的结果。两者关系可以用能量平衡方程描述,能量储存的速率等于能量摄入减去消耗的速率。尽管这种基于简单数学运算的关系可能容易理解,但在现实中,各种已知和未知的系统影响能量平衡的各个组成部分(能量储存,能量摄入,能量消耗)。显然,如果对于能量平衡有完整的理解,有效的预防和治疗策略就不会让肥胖在世界范围内大规模流行。目的是针对能量平衡的组成部分进行简要的概述,确定10个关键主题以及悬而未决的问题,如果这些问题得以解决,可以推动整个研究领域。这些主题涉及多个方面,从一般(方法学问题)到特定领域。这个列表并不是详尽无遗,但却为能量平衡领域的科学家制定了研究议程,为公共卫生专家制定肥胖干预的措施提供了建议。
Abstract: Obesity is the result of a mismatch between the amount of calories consumed and the amount of calories expended during an extended period of time. This relationship is described by the energy balance equation, which states the rate of change in energy storage depots in the body are equal to the rate of energy intake minus the rate of energy expenditure. Although this relationship may appear easy to understand based on simple mathematics, in reality, a variety of known and unknown systems influence the components of energy balance (energy storage, energy intake, energy expenditure). Clearly, if a complete understanding of energy balance was apparent, worldwide levels of obesity would not have reached pandemic proportions due to effective prevention and treatment strategies. The aim of the present article is to provide a brief overview of the components of energy balance and to identify 10 key topics and unanswered questions that would move the research field forward if addressed. These topics are intentionally diverse and range from general themes (e.g., methodological issues) to specific areas (e.g., intensity of exercise required to alter energy intake). Although this list is not meant to be exhaustive, it does provide a research agenda for scientists involved in the study of energy balance and recommendations for public health professionals developingobesity interventions
Efficient algorithms for three-dimensional axial and planar random assignment problems
Alan Frieze,Gregory Sorkin
Computer Science , 2010,
Abstract: Beautiful formulas are known for the expected cost of random two-dimensional assignment problems, but in higher dimensions even the scaling is not known. In three dimensions and above, the problem has natural "Axial" and "Planar" versions, both of which are NP-hard. For 3-dimensional Axial random assignment instances of size $n$, the cost scales as $\Omega(1/n)$, and a main result of the present paper is a linear-time algorithm that, with high probability, finds a solution of cost $O(n^{-1+o(1)})$. For 3-dimensional Planar assignment, the lower bound is $\Omega(n)$, and we give a new efficient matching-based algorithm that with high probability returns a solution with cost $O(n \log n)$.
Average case performance of heuristics for multi-dimensional assignment problems
Alan Frieze,Gregory Sorkin
Computer Science , 2010,
Abstract: We consider multi-dimensional assignment problems in a probabilistic setting. Our main results are: (i) A new efficient algorithm for the 3-dimensional planar problem, based on enumerating and selecting from a set of "alternating-path trees"; (ii) A new efficient matching-based algorithm for the 3-dimensional axial problem.
Evolutionary history of tall fescue morphotypes inferred from molecular phylogenetics of the Lolium-Festuca species complex
Melanie L Hand, Noel OI Cogan, Alan V Stewart, John W Forster
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-303
Abstract: Putative homoeologous sequences from both nuclear genes were obtained from each polyploid species and compared to counterparts from 15 diploid taxa. Phylogenetic reconstruction confirmed F. pratensis and F. arundinacea var. glaucescens as probable progenitors to Continental tall fescue, and these species are also likely to be ancestral to the rhizomatous morphotype. However, these two morphotypes are sufficiently distinct to be located in separate clades based on the ITS-derived data set. All four of the generated data sets suggest independent evolution of the Mediterranean and Continental morphotypes, with minimal affinity between cognate sequence haplotypes. No obvious candidate progenitor species for Mediterranean tall fescues were identified, and only two putative sub-genome-specific haplotypes were identified for this morphotype.This study describes the first phylogenetic analysis of the Festuca genus to include representatives of each tall fescue morphotype, and to use low copy nuclear gene-derived sequences to identify putative progenitors of the polyploid species. The demonstration of distinct tall fescue lineages has implications for both taxonomy and molecular breeding strategies, and may facilitate the generation of morphotype and/or sub-genome-specific molecular markers.The Festuca genus is the largest within the Loliinae subtribe of the Poaceae family, and contains over 500 species of temperate grasses [1]. Species of Festuca vary in morphology, with studies of leaf anatomy and phylogeny based on sequence of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) consistently defining two major evolutionary lineages, of broad and fine-leaved species [1-6]. The genus also varies substantially in ploidy levels, from diploid (2n = 2x = 14) to dodecaploid (2n = 12x = 84), the vast majority of species being allopolyploid [7,8]. One of the most agriculturally important Festuca species is tall fescue (Festuca arundinacea Schreb.); a broad-leaved o
A picture or a 1000 words?
The Turkish Online Journal of Distance Education , 2000,
Ethical Issues in Physiatrist Practice
Hand G
Indian Journal of Physical Medicine and Rehabilitation , 2008,
Abstract: Editorial on Ethical Issues. Medical ethics is at the centre of medical practice. It isrightly gaining much needed renewed focus and attentionin the evolving scenario. The impetus for it may beattributed to the revelations that arose through Nurembergtrials, the framework elements that define research andpublications related compulsions, and indeed the contextand state of affairs of present day medical jurisprudence.The physiatrist’s practice cannot remain untouched bythe moral and ethical dilemmas faced in today’s world.Although the pillars of the specialty are grounded in the
Conditions for Existence of Dual Certificates in Rank-One Semidefinite Problems
Paul Hand
Mathematics , 2013, DOI: 10.4310/CMS.2014.v12.n7.a11
Abstract: Several signal recovery tasks can be relaxed into semidefinite programs with rank-one minimizers. A common technique for proving these programs succeed is to construct a dual certificate. Unfortunately, dual certificates may not exist under some formulations of semidefinite programs. In order to put problems into a form where dual certificate arguments are possible, it is important to develop conditions under which the certificates exist. In this paper, we provide an example where dual certificates do not exist. We then present a completeness condition under which they are guaranteed to exist. For programs that do not satisfy the completeness condition, we present a completion process which produces an equivalent program that does satisfy the condition. The important message of this paper is that dual certificates may not exist for semidefinite programs that involve orthogonal measurements with respect to positive-semidefinite matrices. Such measurements can interact with the positive-semidefinite constraint in a way that implies additional linear measurements. If these additional measurements are not included in the problem formulation, then dual certificates may fail to exist. As an illustration, we present a semidefinite relaxation for the task of finding the sparsest element in a subspace. One formulation of this program does not admit dual certificates. The completion process produces an equivalent formulation which does admit dual certificates.
PhaseLift is robust to a constant fraction of arbitrary errors
Paul Hand
Mathematics , 2015,
Abstract: Consider the task of recovering an unknown $n$-vector from phaseless linear measurements. This task is the phase retrieval problem. Through the technique of lifting, this nonconvex problem may be convexified into a semidefinite rank-one matrix recovery problem, known as PhaseLift. Under a linear number of exact Gaussian measurements, PhaseLift recovers the unknown vector exactly with high probability. Under noisy measurements, the solution to a variant of PhaseLift has error proportional to the $\ell_1$ norm of the noise. In the present paper, we study the robustness of this variant of PhaseLift to a case with noise and gross, arbitrary corruptions. We prove that PhaseLift can tolerate a small, fixed fraction of gross errors, even in the highly underdetermined regime where there are only $O(n)$ measurements. The lifted phase retrieval problem can be viewed as a rank-one robust Principal Component Analysis (PCA) problem under generic rank-one measurements. From this perspective, the proposed convex program is simpler that the semidefinite version of the sparse-plus-low-rank formulation standard in the robust PCA literature. Specifically, the rank penalization through a trace term is unnecessary, and the resulting optimization program has no parameters that need to be chosen. The present work also achieves the information theoretically optimal scaling of $O(n)$ measurements without the additional logarithmic factors that appear in existing general robust PCA results.
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