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Search Results: 1 - 10 of 14061 matches for " William Winfrey "
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Methods used in the Lives Saved Tool (LiST)
Winfrey William,McKinnon Robert,Stover John
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-s3-s32
Abstract: Background Choosing an optimum set of child health interventions for maximum mortality impact is important within resource poor policy environments. The Lives Saved Tool (LiST) is a computer model that estimates the mortality and stillbirth impact of scaling up proven maternal and child health interventions. This paper will describe the methods used to estimate the impact of scaling up interventions on neonatal and child mortality. Model structure and assumptions LiST estimates mortality impact via five age bands 0 months, 1-5 months, 6-11 months, 12-23 months and 24 to 59 months. For each of these age bands reductions in cause specific mortality are estimated. Nutrition interventions can impact either nutritional statuses or directly impact mortality. In the former case, LiST acts as a cohort model where current nutritional statuses such as stunting impact the probability of stunting as the cohort ages. LiST links with a demographic projections model (DemProj) to estimate the deaths and deaths averted due to the reductions in mortality rates. Using LiST LiST can be downloaded at http://www.jhsph.edu/dept/ih/IIP/list/ where simple instructions are available for installation. LiST includes default values for coverage and effectiveness for many less developed countries obtained from credible sources. Conclusions The development of LiST is a continuing process. Via technical inputs from the Child Health Epidemiological Group, effectiveness values are updated, interventions are adopted and new features added.
New Findings for Maternal Mortality Age Patterns: Aggregated Results for 38 Countries
Ann K. Blanc, William Winfrey, John Ross
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0059864
Abstract: Background With recent results showing a global decline in overall maternal mortality during the last two decades and with the target date for achieving the Millennium Development Goals only four years away, the question of how to continue or even accelerate the decline has become more pressing. By knowing where the risk is highest as well as where the numbers of deaths are greatest, it may be possible to re-direct resources and fine-tune strategies for greater effectiveness in efforts to reduce maternal mortality. Methods We aggregate data from 38 Demographic and Health Surveys that included a maternal mortality module and were conducted in 2000 or later to produce maternal mortality ratios, rates, and numbers of deaths by five year age groups, separately by residence, region, and overall mortality level. Findings The age pattern of maternal mortality is broadly similar across regions, type of place of residence, and overall level of maternal mortality. A “J” shaped curve, with markedly higher risk after age 30, is evident in all groups. We find that the excess risk among adolescents is of a much lower magnitude than is generally assumed. The oldest age groups appear to be especially resistant to change. We also find evidence of extremely elevated risk among older mothers in countries with high levels of HIV prevalence. Conclusions The largest number of deaths occurs in the age groups from 20-34, largely because those are the ages at which women are most likely to give birth so efforts directed at this group would most effectively reduce the number of deaths. Yet equity considerations suggest that efforts also be directed toward those most at risk, i.e., older women and adolescents. Because women are at risk each time they become pregnant, fulfilling the substantial unmet need for contraception is a cross-cutting strategy that can address both effectiveness and equity concerns.
Effects of Aluminum Oxide Nanoparticles on the Growth, Development, and microRNA Expression of Tobacco (Nicotiana tabacum)
Caitlin E. Burklew, Jordan Ashlock, William B. Winfrey, Baohong Zhang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034783
Abstract: Nanoparticles are a class of newly emerging environmental pollutions. To date, few experiments have been conducted to investigate the effect nanoparticles may have on plant growth and development. It is important to study the effects nanoparticles have on plants because they are stationary organisms that cannot move away from environmental stresses like animals can, therefore they must overcome these stresses by molecular routes such as altering gene expression. microRNAs (miRNA) are a newly discovered, endogenous class of post-transcriptional gene regulators that function to alter gene expression by either targeting mRNAs for degradation or inhibiting mRNAs translating into proteins. miRNAs have been shown to mediate abiotic stress responses such as drought and salinity in plants by altering gene expression, however no study has been performed on the effect of nanoparticles on the miRNA expression profile; therefore our aim in this study was to classify if certain miRNAs play a role in plant response to Al2O3 nanoparticle stress. In this study, we exposed tobacco (Nicotiana tabacum) plants (an important cash crop as well as a model organism) to 0%, 0.1%, 0.5%, and 1% Al2O3 nanoparticles and found that as exposure to the nanoparticles increased, the average root length, the average biomass, and the leaf count of the seedlings significantly decreased. We also found that miR395, miR397, miR398, and miR399 showed an extreme increase in expression during exposure to 1% Al2O3 nanoparticles as compared to the other treatments and the control, therefore these miRNAs may play a key role in mediating plant stress responses to nanoparticle stress in the environment. The results of this study show that Al2O3 nanoparticles have a negative effect on the growth and development of tobacco seedlings and that miRNAs may play a role in the ability of plants to withstand stress to Al2O3 nanoparticles in the environment.
The Metallicity Distribution Function of Omega Centauri
Peter M. Frinchaboy,Jaehyon Rhee,James C. Ostheimer,Steven R. Majewski,Richard J. Patterson,Winfrey Y. Johnson,Dana Dinescu,Christopher Palma,Kyle B. Westfall,William B. Kunkel
Physics , 2001,
Abstract: We explore the metallicity distribution function (MDF) of red giant stars in Omega Centauri from a catalogue of Washington M, T_2 and DDO51 photometry covering over 1.1 deg^2 outside the cluster core. Using updated calibrations of giant branch isometallicity loci in this filter system, photometric metallicities, guided by previously published spectroscopic abundances, are derived. Several methods are employed to correct the MDF for contamination by Galactic stars, including: (1) use of the surface gravity sensitivity of the (M-DDO51) color index to eliminate foreground dwarf stars, (2) radial velocities, and (3) membership probabilities from proper motions. The contamination-corrected MDF for Omega Cen shows a range of enrichment levels spanning nearly 2 dex in [Fe/H], and with peaks at [Fe/H]=-1.6, -1.2, and -0.9.
Return to Sexual Activity and Modern Family Planning Use in the Extended Postpartum Period: An Analysis of Findings from Seventeen Countries
MR Borda, W Winfrey, C McKaig
African Journal of Reproductive Health , 2011,
Abstract: Unintended pregnancies can lead to poor maternal and child health outcomes. Family planning use during the first year postpartum has the potential to significantly reduce at least some of these unintended pregnancies. This paper examines the relationship of menses return, breastfeeding status, and postpartum duration on return to sexual activity and use of modern family planning among postpartum women. This paper presents results from a secondary data analysis of Demographic and Health Surveys from 17 countries. For postpartum women, the return of menses, breastfeeding status, and postpartum duration are significantly associated with return to sexual activity in at least 10 out of the 17 countries but not consistently associated with family planning use. Only menses return had a significant association with use of modern family planning in the majority of countries. These findings point to the importance of education about pregnancy risk prior to menses return (Afr J Reprod Health 2010; 14[4]: 75-82).
Does Cluster Membership Enhance Financial Performance?  [PDF]
William Ruland
iBusiness (IB) , 2013, DOI: 10.4236/ib.2013.51001
Abstract:

This paper reports upon the profitability of firms that locate their headquarters in same-industry geographic concentrations or clusters and those that opt to maintain headquarters in other locations. While the preponderance of the theoretical and descriptive literature emphasizes the potential benefits associated with clustering, some papers suggest that clustering should not be beneficial, at least for particular types of firms in particular circumstances. This empirical study, which examines a sample of more than 4000 Compustat firms from 86 different industries, compares the profitability of firms in industry clusters and firms in other locations. The sample is partitioned into small and large firms to account for expected differences in profitability, in general, and the possible differential impact of geographic clustering. The results show that for smaller firms, the profitability of cluster members tends to be considerably lower than for firms that opt not to join clusters. For the subsample of larger firms, the results are mixed depending upon the measure of profitability. The results imply that smaller firms should carefully evaluate the decision to locate in industry clusters.

Why do we yawn?  [PDF]
William Burke
Health (Health) , 2013, DOI: 10.4236/health.2013.510213
Abstract:

The biomedical hypothesis proposed here is that the immediate trigger for a yawn is a restricted collapse of a few alveoli in the lungs. The extent of this alveolar collapse may be too small for it to be detected by current X-ray technology, but this technology is continually improving and may soon be good enough to test the hypothesis. In support of the hypothesis, it is shown that yawning can be inhibited by deep breaths of air, nitrogen or carbogen, thus showing that yawning is not triggered by lack of oxygen or by excess carbon dioxide, leaving alveolar collapse as the most likely possibility. A more extensive form of alveolar collapse is termed atelectasis and this involves a serious state of hypoxia which, if deepened or prolonged, can be fatal. Therefore, if the hypothesis is correct, yawning may prevent the development of atelectasis and save lives. This paper is not concerned with other indirect ways in which yawning may be induced, nor with the mechanism and neural circuitry of the yawn, nor with social aspects of yawning, only with the immediate trigger. My aim is to get better evidence for the hypothesis put forward here and also to study the behaviour of the pulmonary alveoli in normal respiration.

The Ionic Composition of Nasal Fluid and Its Function  [PDF]
William Burke
Health (Health) , 2014, DOI: 10.4236/health.2014.68093
Abstract: The aim of the experiments reported here is to increase our understanding of the function of the nasal fluid. It is generally accepted that the nasal fluid assists in the humidification of the inspired air. It also assists in the capture of inspired particles such as pollen, preventing them getting lodged in the lungs. It is also known to contain antibacterial substances which keep the nose, nasopharynx and respiratory passages relatively free of infection. There are other features of the nasal fluid that are not understood. In cold weather, is it the fluid that collects in the nostrils pure water or nasal fluid? Why does nasal fluid have an exceptionally high potassium concentration? Does nasal fluid secreted during the common cold have the same composition as at other times? My objectives are to try to answer these questions. My method is to collect my nasal fluid in several different ways and have the ionic composition of each determined accurately. My findings are that nasal fluid is similar in composition however it is secreted. In cold weather, if expiration is via the nose, the nasal fluid is diluted by condensed water. The high concentration of potassium in the nasal fluid is not a way of controlling the level of potassium in the body but I suggest that it may assist in maintaining the antibacterial property of the nasal fluid.
Coherence Modified for Sensitivity to Relative Phase of Real Band-Limited Time Series  [PDF]
William Menke
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.517261
Abstract: As is well known, coherence does not distinguish the relative phase of a pair of real, sinusoidal time series; the coherence between them is always unity. This behavior can limit the applicability of coherence analysis in the special case where the time series are band-limited (nearly-monoch- romatic) and where sensitivity to phase differences is advantageous. We propose a simple mod-ification to the usual formula for coherence in which the cross-spectrum is replaced by its real part. The resulting quantity behaves similarly to coherence, except that it is sensitive to relative phase when the signals being compared are strongly band-limited. Furthermore, it has a useful interpretation in terms of the zero-lag cross-correlation of real band-passed versions of the time series.
Prediction Distortion in Monte Carlo Tree Search and an Improved Algorithm  [PDF]
William Li
Journal of Intelligent Learning Systems and Applications (JILSA) , 2018, DOI: 10.4236/jilsa.2018.102004
Abstract: Teaching computer programs to play games through machine learning has been an important way to achieve better artificial intelligence (AI) in a variety of real-world applications. Monte Carlo Tree Search (MCTS) is one of the key AI techniques developed recently that enabled AlphaGo to defeat a legendary professional Go player. What makes MCTS particularly attractive is that it only understands the basic rules of the game and does not rely on expert-level knowledge. Researchers thus expect that MCTS can be applied to other complex AI problems where domain-specific expert-level knowledge is not yet available. So far there are very few analytic studies in the literature. In this paper, our goal is to develop analytic studies of MCTS to build a more fundamental understanding of the algorithms and their applicability in complex AI problems. We start with a simple version of MCTS, called random playout search (RPS), to play Tic-Tac-Toe, and find that RPS may fail to discover the correct moves even in a very simple game position of Tic-Tac-Toe. Both the probability analysis and simulation have confirmed our discovery. We continue our studies with the full version of MCTS to play Gomoku and find that while MCTS has shown great success in playing more sophisticated games like Go, it is not effective to address the problem of sudden death/win. The main reason that MCTS often fails to detect sudden death/win lies in the random playout search nature of MCTS, which leads to prediction distortion. Therefore, although MCTS in theory converges to the optimal minimax search, with real world computational resource constraints, MCTS has to rely on RPS as an important step in its search process, therefore suffering from the same fundamental prediction distortion problem as RPS does. By examining the detailed statistics of the scores in MCTS, we investigate a variety of scenarios where MCTS fails to detect sudden death/win. Finally, we propose an improved MCTS algorithm by incorporating minimax search to overcome prediction distortion. Our simulation has confirmed the effectiveness of the proposed algorithm. We provide an estimate of the additional computational costs of this new algorithm to detect sudden death/win and discuss heuristic strategies to further reduce the search complexity.
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