641 research outputs found

    Modeling U.S. Soy-Based Markets with Directed Acyclic Graphs and Bernanke Structural VAR Methods: The Impacts of High Soy Meal and Soybean Prices

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    Advanced methods that combine directed acyclic graphs with Bernanke structural vector autoregression models are applied to a monthly system of three U.S. soy-based markets: for soybeans upstream and for the two soybean co-products soy meal and soy oil further downstream. Analyses of the impulse-response function and forecast error variance decompositions provide updated estimates of market-elasticity parameters that drive these markets and updated policy-relevant information on how these monthly markets run and dynamically interact. Results characterize impacts on the three U.S. soy-based markets of increases in U.S. prices of soy meal and soybeans.Industrial Organization,

    Flight Measurements to Determine Effect of a Spring-Loaded Tab on Longitudinal Stability of an Airplane

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    In conjunction with a program of research on the general problem of stability of airplanes in the climbing condition, tests have been made of a spring-loaded tb which. is referred to as a ?springy tab,? installed on the elevator of a low-wing scout bomber. The tab was arranged to deflect upward with decrease in speed which caused an increase in the pull force required to trim at low speeds and thereby increased the stick-free static longitudinal stability of the airplane. It was found that the springy tab would increase the stick-free stability in all flight conditions, would reduce the danger of inadvertent stalling because of the definite pull force required to stall the airplane with power on, would reduce the effect of center-of-gravity position on stick-free static stability, and would have little effect on the elevator stick forces in accelerated f11ght. Another advantage of the springy tab is that it might be used to provide almost any desired variation of elevator stick force with speed by adjusting the tab hinge-moment characteristics and the variation of spring moment with tab deflection. Unlike the bungee and the bobweight, the springy tab would provide stick-free static stability without requiring a pull force to hold the stick back while taxying. A device similar to the springy tab may be used on the rudder or ailerons to eliminate undesirable trim-force variations with speed

    Mobile Bay Estuary Acoustic Field Experiment

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    Prepared for: The Office of Naval Research, Code 32, and the Office of Naval Research GlobalThe Mobile Bay Estuary Acoustic Field Experiment 2021 (MBE2021) was funded by the Office of Naval Research (ONR) as part of the multi-university Undersea Remote Sensing (USRS) program directed by Dr. Reginald Beach (ONR 322). During the experiment, environmental and acoustic data were collected during June 9-15 in the vicinity of the mouth of Mobile Bay, focused on assessing the impact on acoustic propagation by the tidal intrusion front during flood and the ebb plume front during ebb. This report documents details of the equipment used by the Naval Postgraduate School during the study and presents initial findings. Initial findings indicate (a) that rather than being limited to a surface layer, bubbles are present through the entire water column in the "Dixey V", the persistent feature near Mobile Point formed by the convergence of seawater in the bay mouth during flood; (b) bottom currents in the bay mouth exceed 1 m/s; and (c) the bubble clouds in the Dixey V contribute to effective sound speeds well below the intrinsic sound speed of bubble-free seawater. Results of ongoing analysis will be published in peer-reviewed scientific journals.The Office of Naval Research, Code 32Office of Naval Research GlobalN0001420WX00287Approved for public release; distribution is unlimite

    The usefulness of twenty-four molecular markers in predicting treatment outcome with combination therapy of amodiaquine plus sulphadoxine-pyrimethamine against falciparum malaria in Papua New Guinea

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    <p>Abstract</p> <p>Background</p> <p>In Papua New Guinea (PNG), combination therapy with amodiaquine (AQ) or chloroquine (CQ) plus sulphadoxine-pyrimethamine (SP) was introduced as first-line treatment against uncomplicated malaria in 2000.</p> <p>Methods</p> <p>We assessed <it>in vivo </it>treatment failure rates with AQ+SP in two different areas in PNG and twenty-four molecular drug resistance markers of <it>Plasmodium falciparum </it>were characterized in pre-treatment samples. The aim of the study was to investigate the association between infecting genotype and treatment response in order to identify useful predictors of treatment failure with AQ+SP.</p> <p>Results</p> <p>In 2004, Day-28 treatment failure rates for AQ+SP were 29% in the Karimui and 19% in the South Wosera area, respectively. The strongest independent predictors for treatment failure with AQ+SP were <it>pfmdr1 </it>N86Y (OR = 7.87, <it>p </it>< 0.01) and <it>pfdhps </it>A437G (OR = 3.44, <it>p </it>< 0.01). Mutations found in CQ/AQ related markers <it>pfcrt </it>K76T, A220S, N326D, and I356L did not help to increase the predictive value, the most likely reason being that these mutations reached almost fixed levels. Though mutations in SP related markers <it>pfdhfr </it>S108N and C59R were not associated with treatment failure, they increased the predictive value of <it>pfdhps </it>A437G. The difference in treatment failure rate in the two sites was reflected in the corresponding genetic profile of the parasite populations, with significant differences seen in the allele frequencies of mutant <it>pfmdr1 </it>N86Y, <it>pfmdr1 </it>Y184F, <it>pfcrt </it>A220S, and <it>pfdhps </it>A437G.</p> <p>Conclusion</p> <p>The study provides evidence for high levels of resistance to the combination regimen of AQ+SP in PNG and indicates which of the many molecular markers analysed are useful for the monitoring of parasite resistance to combinations with AQ+SP.</p

    Significant geographical differences in prevalence of mutations associated with Plasmodium falciparum and Plasmodium vivax drug resistance in two regions from Papua New Guinea

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    Drug resistance remains a major obstacle to malaria treatment and control. It can arise and spread rapidly, and vary substantially even at sub-national level. National malaria programmes require cost-effective and timely ways of characterizing drug-resistance at multiple sites within their countries.; An improved multiplexed post-PCR ligase detection reaction-fluorescent microsphere assay (LDR-FMA) was used to simultaneously determine the presence of mutations in chloroquine resistance transporter (crt), multidrug resistance 1 (mdr1), dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes in Plasmodium falciparum (n = 727) and Plasmodium vivax (n = 574) isolates collected in 2006 from cross-sectional community population surveys in two geographically distinct regions (Madang and East Sepik) of Papua New Guinea (PNG) where strong regional differences in in vivo aminoquinoline and antifolate therapeutic efficacy had previously been observed. Data were compared to those of a follow-up survey conducted in 2010.; Despite some very low parasite densities, the assay successfully amplified all P. falciparum and P. vivax loci in 77 and 69 % of samples, respectively. In 2006, prevalences of pfdhfr (59R-108 N) double mutation/wild type pfdhps haplotype, pfcrt SVMNT haplotype (72S-76T double mutation), and 86Y pfmdr1 mutation all exceeded 90 %. For P. vivax, 65 % carried at least two pvdhfr mutations, 97 % the 647P pvdhps mutation and 54 % the 976F pvmdr1 mutation. Prevalence of mutant haplotypes was higher in Madang than East Sepik for pfcrt SVMNT (97.4 vs 83.3 %, p = 0.001), pfdhfr (59R-108 N) (100 vs 90.6 %, p = 0.001), pvdhfr haplotypes (75.8 vs 47.6 %, p = 0.001) and pvmdr1 976F (71.2 vs 26.2 %, p &lt; 0.001). Data from a subsequent Madang survey in 2010 showed that the prevalence of pfdhps mutations increased significantly from &lt;5 % to &gt;30 % (p &lt; 0.001) as did the prevalence of pvdhfr mutant haplotypes (from 75.8 to 97.4 %, p = 0.012).; This LDR-FMA multiplex platform shows feasibility for low-cost, high-throughput, rapid characterization of a broad range of drug-resistance markers in low parasitaemia infections. Significant geographical differences in mutation prevalence correlate with previous genotyping surveys and in vivo trials and may reflect variable drug pressure and differences in health-care access in these two PNG populations

    Antibodies against Merozoite Surface Protein (Msp)-119 Are a Major Component of the Invasion-Inhibitory Response in Individuals Immune to Malaria

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    Antibodies that bind to antigens expressed on the merozoite form of the malaria parasite can inhibit parasite growth by preventing merozoite invasion of red blood cells. Inhibitory antibodies are found in the sera of malaria-immune individuals, however, the specificity of those that are important to this process is not known. In this paper, we have used allelic replacement to construct a Plasmodium falciparum parasite line that expresses the complete COOH-terminal fragment of merozoite surface protein (MSP)-119 from the divergent rodent malaria P. chabaudi. By comparing this transfected line with parental parasites that differ only in MSP-119, we show that antibodies specific for this domain are a major component of the inhibitory response in P. falciparum–immune humans and P. chabaudi–immune mice. In some individual human sera, MSP-119 antibodies dominated the inhibitory activity. The finding that antibodies to a small region of a single protein play a major role in this process has important implications for malaria immunity and is strongly supportive of further understanding and development of MSP-119–based vaccines

    Multidisciplinary Group Clinic Appointments: The Self-Management and Care of Heart Failure (SMAC-HF) Trial

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    Background—This trial tested the effects of multidisciplinary group clinic appointments on the primary outcome of time to first heart failure (HF) rehospitalization or death. Methods and Results—HF patients (n=198) were randomly assigned to standard care or standard care plus multidisciplinary group clinics. The group intervention consisted of 4 weekly clinic appointments and 1 booster clinic at month 6, where multidisciplinary professionals engaged patients in HF self-management skills. Data were collected prospectively for 12 months beginning after completion of the first 4 group clinic appointments (2 months post randomization). The intervention was associated with greater adherence to recommended vasodilators (P=0.04). The primary outcome (first HF-related hospitalization or death) was experienced by 22 (24%) in the intervention group and 30 (28%) in standard care. The total HF-related hospitalizations, including repeat hospitalizations after the first time, were 28 in the intervention group and 45 among those receiving standard care. The effects of treatment on rehospitalization varied significantly over time. From 2 to 7 months post randomization, there was a significantly longer hospitalization-free time in the intervention group (Cox proportional hazard ratio=0.45 (95% confidence interval, 0.21–0.98; P=0.04). No significant difference between groups was found from month 8 to 12 (hazard ratio=1.7; 95% confidence interval, 0.7–4.1). Conclusions—Multidisciplinary group clinic appointments were associated with greater adherence to selected HF medications and longer hospitalization-free survival during the time that the intervention was underway. Larger studies will be needed to confirm the benefits seen in this trial and identify methods to sustain these benefits

    Plasmodium falciparum resistance to anti-malarial drugs in Papua New Guinea: evaluation of a community-based approach for the molecular monitoring of resistance

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    ABSTRACT: BACKGROUND: Molecular monitoring of parasite resistance has become an important complementary tool in establishing rational anti-malarial drug policies. Community surveys provide a representative sample of the parasite population and can be carried out more rapidly than accrual of samples from clinical cases, but it is not known whether the frequencies of genetic resistance markers in clinical cases differ from those in the overall population, or whether such community surveys can provide good predictions of treatment failure rates. METHODS: Between 2003 and 2005, in vivo drug efficacy of amodiaquine or chloroquine plus sulphadoxine-pyrimethamine was determined at three sites in Papua New Guinea. The genetic drug resistance profile (i.e., 33 single nucleotide polymorphisms in Plasmodium falciparum crt, mdr1, dhfr, dhps, and ATPase6) was concurrently assessed in 639 community samples collected in the catchment areas of the respective health facilities by using a DNA microarray-based method. Mutant allele and haplotype frequencies were determined and their relationship with treatment failure rates at each site in each year was investigated. RESULTS: PCR-corrected in vivo treatment failure rates were between 12% and 28% and varied by site and year with variable longitudinal trends. In the community samples, the frequencies of mutations in pfcrt and pfmdr1 were high and did not show significant changes over time. Mutant allele frequencies in pfdhfr were moderate and those in pfdhps were low. No mutations were detected in pfATPase6. There was much more variation between sites than temporal, within-site, variation in allele and haplotype frequencies. This variation did not correlate well with treatment failure rates. Allele and haplotype frequencies were very similar in clinical and community samples from the same site. CONCLUSIONS: The relationship between parasite genetics and in vivo treatment failure rate is not straightforward. The frequencies of genetic anti-malarial resistance markers appear to be very similar in community and clinical samples, but cannot be used to make precise predictions of clinical outcome. Thus, indicators based on molecular data have to be considered with caution and interpreted in the local context, especially with regard to prior drug usage and level of pre-existing immunity. Testing community samples for molecular drug resistance markers is a complementary tool that should help decision-making for the best treatment options and appropriate potential alternative

    The circularly permuted globin domain of androglobin exhibits atypical heme stabilization and nitric oxide interaction

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    In the decade since the discovery of androglobin, a multi-domain hemoglobin of metazoans associated with ciliogenesis and spermatogenesis, there has been little advance in the knowledge of the biochemical and structural properties of this unusual member of the hemoglobin superfamily. Using a method for aligning remote homologues, coupled with molecular modelling and molecular dynamics, we have identified a novel structural alignment to other hemoglobins. This has led to the first stable recombinant expression and characterization of the circularly permuted globin domain. Exceptional for eukaryotic globins is that a tyrosine takes the place of the highly conserved phenylalanine in the CD1 position, a critical point in stabilizing the heme. A disulfide bond, similar to that found in neuroglobin, forms a closed loop around the heme pocket, taking the place of androglobin's missing CD loop and further supporting the heme pocket structure. Highly unusual in the globin superfamily is that the heme iron binds nitric oxide as a five-coordinate complex similar to other heme proteins that have nitric oxide storage functions. With rapid autoxidation and high nitrite reductase activity, the globin appears to be more tailored toward nitric oxide homeostasis or buffering. The use of our multi-template profile alignment method to yield the first biochemical characterisation of the circularly permuted globin domain of androglobin expands our knowledge of the fundamental functioning of this elusive protein and provides a pathway to better define the link between the biochemical traits of androglobin with proposed physiological functions

    Comparisons among ten models of acoustic backscattering used in aquatic ecosystem research

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    Author Posting. © Acoustical Society of America, 2015. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 138 (2015); 3742, doi:10.1121/1.4937607.Analytical and numerical scatteringmodels with accompanying digital representations are used increasingly to predict acoustic backscatter by fish and zooplankton in research and ecosystem monitoring applications. Ten such models were applied to targets with simple geometric shapes and parameterized (e.g., size and material properties) to represent biological organisms such as zooplankton and fish, and their predictions of acoustic backscatter were compared to those from exact or approximate analytical models, i.e., benchmarks. These comparisons were made for a sphere, spherical shell, prolate spheroid, and finite cylinder, each with homogeneous composition. For each shape, four target boundary conditions were considered: rigid-fixed, pressure-release, gas-filled, and weakly scattering. Target strength (dB re 1 m2) was calculated as a function of insonifying frequency (f = 12 to 400 kHz) and angle of incidence (θ = 0° to 90°). In general, the numerical models (i.e., boundary- and finite-element) matched the benchmarks over the full range of simulation parameters. While inherent errors associated with the approximate analytical models were illustrated, so were the advantages as they are computationally efficient and in certain cases, outperformed the numerical models under conditions where the numerical models did not convergeThis work was supported by the NOAA Fisheries Advanced Sampling Technologies Working Group, the Office of Naval Research, and the National Oceanic Partnership Program. Josiah S. Renfree
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