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Search Results: 1 - 10 of 152522 matches for " Dennis H Osmond "
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Factors associated with mortality in patients with drug-susceptible pulmonary tuberculosis
Payam Nahid, Leah G Jarlsberg, Irina Rudoy, Bouke C de Jong, Alon Unger, L Masae Kawamura, Dennis H Osmond, Philip C Hopewell, Charles L Daley
BMC Infectious Diseases , 2011, DOI: 10.1186/1471-2334-11-1
Abstract: Retrospective chart review of patients with drug-susceptible tuberculosis reported to the San Francisco Tuberculosis Control Program from 1990-2001.Of 565 patients meeting eligibility criteria, 37 (6.6%) died during the study period. Of 37 deaths, 12 (32.4%) had tuberculosis listed as a contributing factor. In multivariate analysis controlling for follow-up time, four characteristics were independently associated with mortality: HIV co-infection (HR = 2.57, p = 0.02), older age at tuberculosis diagnosis (HR = 1.52 per 10 years, p = 0.001); initial sputum smear positive for acid fast bacilli (HR = 3.07, p = 0.004); and experiencing an interruption in tuberculosis therapy (HR = 3.15, p = 0.002). The association between treatment interruption and risk of death was due to non-adherence during the intensive phase of treatment (HR = 3.20, p = 0.001). The median duration of treatment interruption did not differ significantly in either intensive or continuation phases between those who died and survived (23 versus 18 days, and 37 versus 29 days, respectively). No deaths were directly attributed to adverse drug reactions.In addition to advanced age, HIV and characteristics of advanced tuberculosis, experiencing an interruption in anti-tuberculosis therapy, primarily due to non-adherence, was also independently associated with increased risk of death. Improving adherence early during treatment for tuberculosis may both improve tuberculosis outcomes as well as decrease mortality.Tuberculosis is a leading cause of death worldwide. According to the World Health Organization (WHO) over 1.7 million people with tuberculosis died in 2008 [1]. Advanced age, male gender, delays in diagnosis and treatment, drug resistance, and co-morbid conditions including HIV co-infection, diabetes, renal disease and COPD, have been associated with increased risk of death in patients with active tuberculosis [2-8]. A substantial proportion of deaths occur during tuberculosis treatment despite patient
Die reaksie van die diatoom gemeenskapstruktuur op endosulfiene blootstelling: ‘n Mesocosm benadering
Steven Osmond
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2012, DOI: 10.4102/satnt.v31i1.327
Comparison of the reproducibility of 2D doppler and 3D STIC in the measurement of fetal cardiac output  [PDF]
Rajeswari Parasuraman, Clive Osmond, David T. Howe
Open Journal of Obstetrics and Gynecology (OJOG) , 2011, DOI: 10.4236/ojog.2011.14031
Abstract: Objectives: Two methods have been described to assess fetal cardiac output (CO). It has usually been calculated by using 2D ultrasound to measure the diameter of outflow valves and Doppler ultrasound to measure flow velocity through the valves. Recently CO has been assessed using 3D spatio-temporal image correlation (STIC) to measure stroke volume. We aimed to compare the reproducibility of these techniques. Methods: In 27 women with singleton pregnancies, examinations were performed in three gestational age groups: 13 - 15, 19 - 21 and >30 weeks of gestation. Each mother was scanned once. Using 2D pulsed wave Doppler the duration of flow and average flow velocity in systole were measured through aortic and pulmonary valves. We averaged values from three consecutive Doppler complexes. The outlet valve diameters were measured and the cardiac output was calculated for each valve. The measurements were repeated to assess reproducibility. In the same women, we acquired STIC volumes of the fetal heart. The volume measurements were made using the 3D Slice method by one observer. Using 2 mm slices the circumference of the ventricles was traced at the end of systole and diastole to calculate ventricular volume before and after contractions to calculate stroke volume and hence cardiac output. The measurements were repeated to assess reproducibility. Results: The root mean square difference of log (CO) of repeat measurements ranged between 0.12 and 0.21 using Doppler compared to 0.7 to 1.47 using STIC. The differences in reproducibility reached statistical significance for both sides of the heart at all but one gestation. Conclusions: We found that Doppler assessment of fetal cardiac output was more reproducible than measurement using STIC.
Gestation-specific reference intervals for fetal cardiac Doppler indices from 12 to 40 weeks of gestation  [PDF]
Rajeswari Parasuraman, Clive Osmond, David T. Howe
Open Journal of Obstetrics and Gynecology (OJOG) , 2013, DOI: 10.4236/ojog.2013.31019

We aimed to establish gestation age specific reference intervals for Doppler indices of fetal cardiac function from 12 to 40 weeks of pregnancy. In a cross-sectional observational study of singleton pregnancies, examinations were performed in 221 women evenly distributed across each week of pregnancy. Blood flow through the four cardiac valves was examined with Doppler. For the atrioventricular valves, velocity and duration of early (E) and atrial (A) waves and the interval (a) between E/A complexes was recorded. For the outflow valves, the duration (b), peak and average velocity of flow in systole was measured. Myocardial performance index (MPI) was calculated as (a - b)/b. Outlet valve diameters were measured and cardiac outputs were calculated. Gestation age specific ranges were constructed for all these parameters. We demonstrated that the cardiac output, peak systolic and time-averaged velocity increase with advancing gestation. However the MPI and E/A ratios show little change across gestation. Fetal cardiac physiology can be studied and Doppler indices reliably measured as early as the late first trimester of pregnancy. Establishing gestation age specific ranges for various cardiac indices throughout pregnancy will help the study of development of fetal cardiac function.

Landform resources for territorial nettle-feeding Nymphalid butterflies: biases at different spatial scales
Dennis, R. H.
Animal Biodiversity and Conservation , 2004,
Abstract: Observations of perch sites for three territorial nymphalid butterflies reveals a bias in landform use at two spatial scales: at macro-scale, sunlit wood edges at the top of slopes; at micro-scale, molehills and bare ground compared to vegetation substrates. There is a hierarchy in landform exploitation; slope and edge position outweighsmicro-landform feature use. Landforms for territories tend to be prominent landmarks. This is especially the case at macro-scale (e.g., wood edges and corners); though also the case at micro-scale (e.g.; molehills, earth bank edge) it is not invariably the case and highly apparent substrates (white boards) entered into territories were ignored. The predominant characteristic of all landforms chosen is that they are all hotspots: warm and sheltered sites. Substrates used for perching change with ambient conditions. In cool spring weather warm sites are essential for territorial defence, acquisition of females and predator evasion. As air temperatures increase there is an increasing propensity for territorial incumbents to use non-apparent, vegetation substrates. Bare earth sites are suggested to be important habitat components for butterfly biology as is their continued renewal through human activity.
Effect of Ambient UV-B on Stomatal Density, Conductance and Isotope Discrimination in Four Field Grown Soybean [Glycine max (L.) Merr.] Isolines  [PDF]
Dennis C. Gitz III, Steven J. Britz, Joseph H. Sullivan
American Journal of Plant Sciences (AJPS) , 2013, DOI: 10.4236/ajps.2013.412A3012

An experiment was designed to test whether ambient levels of UV-B radiation affect stomatal development, decrease stomatal density, and lead to increased water-use efficiency (WUE). Soybean [Glycine max (L.) Merr.] isolines with different stomatal distribution and flavonol expression patterns were field grown under shelters that either transmitted or blocked solar UV-B. All isolines exposed to solar UV-B accumulated higher concentrations of UV-screening phenolic pigments but other responses were isoline dependent. Solar UV-B decreased stomatal density and conductance in isolines expressing a unique branched kaempferol triglycoside. Decreased stomatal density was associated with increased season-long WUE and decreased internal CO2 concentration of leaf (estimated by δ13C discrimination). We concluded that photomorphogenic responses to UV-B affected stomatal density and WUE in field grown soybean; but that the magnitude and direction of these response were associated with isogenic pleiotropic differences in stomatal distribution and pigment expression. UV-B radiation had no effect on biomass accumulation or yield in a cultivar expressing only trace levels of kaempferol suggesting that flavonol expression is not prerequisite to UV-B tolerance.

Servant Leadership as A Leadership Model
Osmond C. Ingram, Jr.
Journal of Management Science and Business Intelligence , 2016, DOI: 10.5281/zenodo.376750
Abstract: Research and popular writing on the subject of leadership continues at a rapid pace. The leadership section at local bookstores and libraries gives evidence to the growing number of volumes written from numerous perspectives and from a wide range of experience. There appears to be no quarrel with the idea that leadership is in short supply, yet it is vitally important to every type of organization. Within this mass of literature are those who explore various theories, approaches, and styles, as well as those who offer their own brand of leadership principles that are sure to solve the leadership problems of most any organization. Though no longer an unknown model, servant leadership is seeing increased research through scholarly articles, dissertations, and books on this relatively new approach to leadership. Servant leadership is not based on a complicated set of guidelines; however, some basic tenets have been researched, studied and compiled by a host of scholars and popular speakers. It is interesting that, in spite of the extent of available literature, many people are unable to clearly define servant leadership. This presentation will contribute to defining servant leadership, explain its genesis and concepts, and offer the model as an option for effective leadership in organizations.
A Systematic Review on the Diagnosis of Pediatric Bacterial Pneumonia: When Gold Is Bronze
Tim Lynch,Liza Bialy,James D. Kellner,Martin H. Osmond,Terry P. Klassen,Tamara Durec,Robin Leicht,David W. Johnson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0011989
Abstract: In developing countries, pneumonia is one of the leading causes of death in children under five years of age and hence timely and accurate diagnosis is critical. In North America, pneumonia is also a common source of childhood morbidity and occasionally mortality. Clinicians traditionally have used the chest radiograph as the gold standard in the diagnosis of pneumonia, but they are becoming increasingly aware that it is not ideal. Numerous studies have shown that chest radiography findings lack precision in defining the etiology of childhood pneumonia. There is no single test that reliably distinguishes bacterial from non-bacterial causes. These factors have resulted in clinicians historically using a combination of physical signs and chest radiographs as a ‘gold standard’, though this combination of tests has been shown to be imperfect for diagnosis and assigning treatment. The objectives of this systematic review are to: 1) identify and categorize studies that have used single or multiple tests as a gold standard for assessing accuracy of other tests, and 2) given the ‘gold standard’ used, determine the accuracy of these other tests for diagnosing childhood bacterial pneumonia.
Hybrid graphene-quantum dot phototransistors with ultrahigh gain
Gerasimos Konstantatos,Michela Badioli,Louis Gaudreau,Johann Osmond,Maria Bernechea,Pelayo Garcia de Arquer,Fabio Gatti,Frank H. L. Koppens
Physics , 2011,
Abstract: Graphene has emerged as a novel platform for opto-electronic applications and photodetector, but the inefficient conversion from light to current has so far been an important roadblock. The main challenge has been to increase the light absorption efficiency and to provide a gain mechanism where multiple charge carriers are created from one incident photon. Here, we take advantage of the strong light absorption in quantum dots and the two-dimensionality and high mobility of graphene to merge these materials into a hybrid system for photodetection with extremely high sensitivity. Exploiting charge transfer between the two materials, we realize for the first time, graphene-based phototransistors that show ultrahigh gain of 10^8 and ten orders of magnitude larger responsivity compared to pristine graphene photodetectors. These hybrid graphene-quantum dot phototransistors exhibit gate-tunable sensitivity, spectral selectivity from the shortwave infrared to the visible, and can be integrated with current circuit technologies.
Structural Determinants of Photoreactivity of Triplex Forming Oligonucleotides Conjugated to Psoralens
Rajagopal Krishnan,Dennis H. Oh
Journal of Nucleic Acids , 2010, DOI: 10.4061/2010/523498
Abstract: Triplex-forming oligonucleotides (TFOs) with both DNA and -O-methyl RNA backbones can direct psoralen photoadducts to specific DNA sequences. However, the functional consequences of these differing structures on psoralen photoreactivity are unknown. We designed TFO sequences with DNA and -O-methyl RNA backbones conjugated to psoralen by 2-carbon linkers and examined their ability to bind and target damage to model DNA duplexes corresponding to sequences within the human HPRT gene. While TFO binding affinity was not dramatically affected by the type of backbone, psoralen photoreactivity was completely abrogated by the -O-methyl RNA backbone. Photoreactivity was restored when the psoralen was conjugated to the RNA TFO via a 6-carbon linker. In contrast to the B-form DNA of triplexes formed by DNA TFOs, the CD spectra of triplexes formed with -O-methyl RNA TFOs exhibited features of A-form DNA. These results indicate that -O-methyl RNA TFOs induce a partial B-to-A transition in their target DNA sequences which may impair the photoreactivity of a conjugated psoralen and suggest that optimal design of TFOs to target DNA damage may require a balance between binding ability and drug reactivity. 1. Introduction Psoralens plus ultraviolet A (UVA) therapy are widely used in the treatment of psoriasis and other inflammatory skin diseases. Psoralens intercalate at TA sites and react with thymines upon exposure to UVA. With absorption of the first UVA photon, psoralens form monoadducts (MA), and subsequent exposures may convert furan-sided MA to interstrand crosslinks (XL). This ability to manipulate lesion formation makes psoralens attractive agents for studying DNA damage and repair and for potentially controlling the therapeutic response. Triplex-forming oligonucleotides (TFOs) offer a promising approach to target drugs such as psoralens to specific genes of interest in living cells. However the metabolic activities and electrostatic forces of the cell introduce a major obstacle to this interesting drug delivery system. In order to overcome barriers to intracellular binding to DNA, TFOs have been extensively engineered. One strategy has been to utilize -O-methyl RNA which has been reported to significantly enhance the binding affinity relative to DNA-based TFOs [1–5]. It has been suggested that the C -endo conformation of the ribose sugar is appropriate for triplex formation [6, 7] and that -O-methyl RNA enhances the TFO association rate without hindering the activity of a psoralen conjugated at the terminus [1, 8]. However, the C -endo conformation of an RNA TFO
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