1,132 research outputs found

    Isospectral Mathieu-Hill Operators

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    In this paper we prove that the spectrum of the Mathieu-Hill Operators with potentials ae^{-i2{\pi}x}+be^{i2{\pi}x} and ce^{-i2{\pi}x}+de^{i2{\pi}x} are the same if and only if ab=cd, where a,b,c and d are complex numbers. This result implies some corollaries about the extension of Harrell-Avron-Simon formula. Moreover, we find explicit formulas for the eigenvalues and eigenfunctions of the t-periodic boundary value problem for the Hill operator with Gasymov's potential

    Studies on oxamyl : analytical method development and investigation of fate in peach seedlings and corn seeds

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    A high performance liquid chromatographic method employing two columns connected in series and separated~y·a.switching valve has been developed for the analysis of the insecticide/ nematicide oxamyl (methyl-N' ,N'-dimethyl-N-[(methylcarbamoyl) oxy]-l-thiooxarnimidate) and two of its metabolites. A variation of this method involving two reverse phase columns was employed to monitor the persistence and translocation of oxamyl in treated peach seedlings. It was possible to simultaneously analyse for oxamyl and its corresponding oxime (methyl-N',N'-dimethyl-N-hydroxy-l-thiooxamimidate}, a major metabolite of oxamyl in plants, without prior cleanup of the samples. The method allowed detection of 0.058 pg oxamyl and 0.035 p.g oxime. On treated peach leaves oxamyl was found to dissipate rapidly during the first two-week period, followed by a period of slow decomposition. Movement of oxamyl or its oxime did not occur in detectable quantities to untreated leaves or to the root or soil. A second variation of the method which employed a size exclusion column as·the first column and a reverse phase column as the second was used to monitor the degradation of oxamyl in treated, planted corn seeds and was suitable for simultaneous analysis of oxamyl, its oxime and dimethylcyanoformamide (DMCF), a metabolite of oxamyl. The method allowed detection of 0.02 pg oxamyl, 0.02 p.g oxime and 0.005 pg DMCF. Oxamyl was found to persist for a period of 5 - 6 weeks, which is long enough to permit oxamyl seedtreatment to be considered as a potential means of protecting young corn plants from nematode attack. Decomposition was found to be more rapid in unsterilized soil than in sterililized soil. DMCF was found to have a nematostatic effect at high concentrations ( 2,OOOpprn), but at lower concentrations no effect on nematode mobility was observed. Oxamyl, on the other hand, was found to reduce the mobility of nematodes at concentrations down to 4 ppm

    Decision-Model Estimation of the Age-Specific Disability Weight for Schistosomiasis Japonica: A Systematic Review of the Literature

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    Schistosomiasis is among the most prevalent parasitic infections worldwide. However, current Global Burden of Disease (GBD) disability-adjusted life year estimates indicate that its population-level impact is negligible. Recent studies suggest that GBD methodologies may significantly underestimate the burden of parasitic diseases, including schistosomiasis. Furthermore, strain-specific disability weights have not been established for schistosomiasis, and the magnitude of human disease burden due to Schistosoma japonicum remains controversial. We used a decision model to quantify an alternative disability weight estimate of the burden of human disease due to S. japonicum. We reviewed S. japonicum morbidity data, and constructed decision trees for all infected persons and two age-specific strata, <15 years (y) and ≥15 y. We conducted stochastic and probabilistic sensitivity analyses for each model. Infection with S. japonicum was associated with an average disability weight of 0.132, with age-specific disability weights of 0.098 (<15 y) and 0.186 (≥15 y). Re-estimated disability weights were seven to 46 times greater than current GBD measures; no simulations produced disability weight estimates lower than 0.009. Nutritional morbidities had the greatest contribution to the S. japonicum disability weight in the <15 y model, whereas major organ pathologies were the most critical variables in the older age group. GBD disability weights for schistosomiasis urgently need to be revised, and species-specific disability weights should be established. Even a marginal increase in current estimates would result in a substantial rise in the estimated global burden of schistosomiasis, and have considerable implications for public health prioritization and resource allocation for schistosomiasis research, monitoring, and control

    Appetite, energy intake, and PYY3-36 responses to energy-matched continuous exercise and submaximal high-intensity exercise.

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    High-intensity intermittent exercise induces physiological adaptations similar to energy-matched continuous exercise, but the comparative appetite and energy balance responses are unknown. Twelve healthy males (mean ± SD: age, 22 ± 3 years; body mass index, 23.7 ± 3.0 kg·m(-2); maximum oxygen uptake, 52.4 ± 7.1 mL·kg(-1)·min(-1)) completed three 8 h trials (control, steady-state exercise (SSE), high-intensity intermittent exercise (HIIE)) separated by 1 week. Trials commenced upon completion of a standardized breakfast. Exercise was performed from hour 2 to hour 3. In SSE, 60 min of cycling at 59.5% ± 1.6% of maximum oxygen uptake was performed. In HIIE, ten 4-min cycling intervals were completed at 85.8% ± 4.0% of maximum oxygen uptake, with a 2-min rest between each interval. A standardized lunch and an ad libitum afternoon meal were provided at hours 3.75 and 7, respectively. Appetite ratings and peptide YY3-36 concentrations were measured throughout each trial. Appetite was acutely suppressed during exercise, but more so during HIIE (p < 0.05). Peptide YY3-36 concentrations increased significantly upon cessation of exercise in SSE (p = 0.002), but were highest in the hours after exercise in HIIE (p = 0.05). Exercise energy expenditure was not different between HIIE and SSE (p = 0.649), but perceived exertion was higher in HIIE (p < 0.0005). Ad libitum energy intake did not differ between trials (p = 0.833). Therefore, relative energy intake (energy intake minus the net energy expenditure of exercise) was lower in the SSE and HIIE trials than in the control trial (control, 4759 ± 1268 kJ; SSE, 2362 ± 1224 kJ; HIIE, 2523 ± 1402 kJ; p < 0.0005). An acute bout of energy-matched continuous exercise and HIIE were equally effective at inducing an energy deficit without stimulating compensatory increases in appetite

    Socio-cultural norms of body size in Westerners and Polynesians affect heart rate variability and emotion during social interactions

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    The perception of body size and thus weight-related stigmatization vary between cultures. Both are stronger in Western than in Polynesian societies. Negative emotional experiences alter one’s behavioral, psychological, and physiological reactions in social interactions. This study compared affective and autonomic nervous system responses to social interactions in Germany and American Samoa, two societies with different body-size related norms. German (n = 55) and Samoan (n = 56) volunteers with and without obesity participated in a virtual ball-tossing game that comprised episodes of social inclusion and social exclusion. During the experiment, heart rate was measured and parasympathetic activity (i.e., high-frequency heart rate variability) was analyzed. We found differences in both emotional experience and autonomic cardio-regulation between the two cultures: during social inclusion, Germans but not Samoans showed increased parasympathetic activity. In Germans with obesity, this increase was related to a more negative body image (comprising high rates of weight-related teasing). During social exclusion, Samoans showed parasympathetic withdrawal regardless of obesity status, while Germans with obesity showed a stronger increase in parasympathetic activity than lean Germans. Furthermore, we found fewer obesity-related differences in emotional arousal after social exclusion in Samoans as compared to Germans. Investigating the interplay of socio-cultural, psychological, and biological aspects, our results suggest influences of body size-related socio-cultural norms on parasympathetic cardio-regulation and negative emotions during social interactions

    Theobromine for the treatment of persistent cough: A randomised, multicentre, double-blind, placebo-controlled clinical trial

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    © Journal of Thoracic Disease. Background: To investigate the effect of BC1036 on health-related quality of life (QOL) in subjects with persistent cough. The secondary objective was to investigate the effect of BC1036 on subjective cough severity. Methods: This was a randomised, multicentre, double-blind, placebo-controlled, parallel-group study in 289 subjects with persistent cough. Subjects received BC1036 or placebo twice daily for 14 days. The primary endpoint comprised cough-related QOL assessed using the validated Leicester Cough Questionnaire (LCQ) at Day 14. Secondary endpoints comprised the LCQ scores at Day 7 and Day 28, cough severity VAS scores at each visit and pulmonary function tests. Results: At baseline, mean total LCQ score in the BC1036 group was lower (i.e., worse QOL) than placebo (P < 0.001), indicating significant between-group heterogeneity. Mean baseline-adjusted change in LCQ score at Day 14 was greater for BC1036 [mean (SD) 2.4±3.5] compared to placebo [mean (SD) score 2.2±3.0], but did not reach statistical significance (P=0.60). Mean cough severity VAS score decreased to a greater extent in the BC1036 group compared to placebo, but again the results were not statistically significant (-12.2±23.28 in BC1036 group and -11.0±21.34 in placebo group at Day 14, P=0.688). There was no significant change in pulmonary function measurements. The adverse event (AE) profile was similar in both groups. Conclusions: This study showed that BC1036 was well tolerated and, although the primary endpoint did not achieve statistical significance, the magnitude of improvement was greater with BC1036 compared to placebo with respect to improving QOL and reducing cough severity. Clinical trial registration: ClinicalTrials.gov: NCT01656668

    A tagging SNP in INSIG2 is associated with obesity-related phenotypes among Samoans

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    <p>Abstract</p> <p>Background</p> <p>A genome wide association study found significant association of a sequence variant, rs7566605, in the insulin-induced gene 2 (<it>INSIG2</it>) with obesity. However, the association remained inconclusive in follow-up studies. We tested for association of four tagging SNPs (tagSNPs) including this variant with body mass index (BMI) and abdominal circumference (ABDCIR) in the Samoans of the Western Pacific, a population with high levels of obesity.</p> <p>Methods</p> <p>We studied 907 adult Samoan participants from a longitudinal study of adiposity and cardiovascular disease risk in two polities, American Samoa and Samoa. Four tagSNPs were identified from the Chinese HapMap database based on pairwise <it>r</it><sup><it>2 </it></sup>of ≥0.8 and minor allele frequency of ≥0.05. Genotyping was performed using the TaqMan assay. Tests of association with BMI and ABDCIR were performed under the additive model.</p> <p>Results</p> <p>We did not find association of rs7566605 with either BMI or ABDCIR in any group of the Samoans. However, the most distally located tagSNPs in Intron 3 of the gene, rs9308762, showed significant association with both BMI (p-value 0.024) and ABDCIR (p-value 0.009) in the combined sample and with BMI (p-value 0.038) in the sample from Samoa.</p> <p>Conclusion</p> <p>Although rs7566605 was not significantly associated with obesity in our study population, we can not rule out the involvement of <it>INSIG2 </it>in obesity related traits as we found significant association of another tagSNP in <it>INSIG2 </it>with both BMI and ABDCIR. This study suggests the importance of comprehensive assessment of sequence variants within a gene in association studies.</p

    Statistical mechanics of voting

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    Decision procedures aggregating the preferences of multiple agents can produce cycles and hence outcomes which have been described heuristically as `chaotic'. We make this description precise by constructing an explicit dynamical system from the agents' preferences and a voting rule. The dynamics form a one dimensional statistical mechanics model; this suggests the use of the topological entropy to quantify the complexity of the system. We formulate natural political/social questions about the expected complexity of a voting rule and degree of cohesion/diversity among agents in terms of random matrix models---ensembles of statistical mechanics models---and compute quantitative answers in some representative cases.Comment: 9 pages, plain TeX, 2 PostScript figures included with epsf.tex (ignore the under/overfull \vbox error messages
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