369 research outputs found
Queen control of a key life-history event in a eusocial insect
In eusocial insects, inclusive fitness theory predicts potential queen–worker conflict over the timing of events in colony life history. Whether queens or workers control the timing of these events is poorly understood. In the bumble-bee Bombus terrestris, queens exhibit a ‘switch point’ in which they switch from laying diploid eggs yielding females (workers and new queens) to laying haploid eggs yielding males. By rearing foundress queens whose worker offspring were removed as pupae and sexing their eggs using microsatellite genotyping, we found that queens kept in the complete absence of adult workers still exhibit a switch point. Moreover, the timing of their switch points relative to the start of egg-laying did not differ significantly from that of queens allowed to produce normal colonies. The finding that bumble-bee queens can express the switch point in the absence of workers experimentally demonstrates queen control of a key life-history event in eusocial insects. In addition, we found no evidence that workers affect the timing of the switch point either directly or indirectly via providing cues to queens, suggesting that workers do not fully express their interests in queen–worker conflicts over colony life history
Roy-Steiner equations for pion-nucleon scattering
Starting from hyperbolic dispersion relations, we derive a closed system of
Roy-Steiner equations for pion-nucleon scattering that respects analyticity,
unitarity, and crossing symmetry. We work out analytically all kernel functions
and unitarity relations required for the lowest partial waves. In order to
suppress the dependence on the high-energy regime we also consider once- and
twice-subtracted versions of the equations, where we identify the subtraction
constants with subthreshold parameters. Assuming Mandelstam analyticity we
determine the maximal range of validity of these equations. As a first step
towards the solution of the full system we cast the equations for the
partial waves into the form of a Muskhelishvili-Omn\`es
problem with finite matching point, which we solve numerically in the
single-channel approximation. We investigate in detail the role of individual
contributions to our solutions and discuss some consequences for the spectral
functions of the nucleon electromagnetic form factors.Comment: 106 pages, 18 figures; version published in JHE
Effect of synthetic hormones on reproduction in Mastomys natalensis
Rodent pest management traditionally relies on some form of lethal control. Developing effective fertility control for pest rodent species could be a major breakthrough particularly in the context of managing rodent population outbreaks. This laboratory-based study is the first to report on the effects of using fertility compounds on an outbreaking rodent pest species found throughout sub-Saharan Africa. Mastomys natalensis were fed bait containing the synthetic steroid hormones quinestrol and levonorgestrel, both singly and in combination, at three concentrations (10, 50, 100 ppm) for seven days. Consumption of the bait and animal body mass was mostly the same between treatments when analysed by sex, day and treatment. However, a repeated measures ANOVA indicated that quinestrol and quinestrol+levonorgestrel treatments reduced consumption by up to 45%, particularly at the higher concentrations of 50 and 100 ppm. Although there was no clear concentration effect on animal body mass, quinestrol and quinestrol+levonorgestrel lowered body mass by up to 20% compared to the untreated and levonorgestrel treatments. Quinestrol and quinestrol+levonorgestrel reduced the weight of male rat testes, epididymis and seminal vesicles by 60-80%, and sperm concentration and motility were reduced by more than 95%. No weight changes were observed to uterine and ovarian tissue; however, high uterine oedema was observed among all female rats consuming treated bait at 8 days and 40 days from trial start. Trials with mate pairing showed there were significant differences in the pregnancy rate with all treatments when compared to the untreated control group of rodents
Leisure-Time Sedentary Behavior, Alcohol Consumption, and Sexual Intercourse Among Adolescents Aged 12-15 Years in 19 Countries From Africa, the Americas, and Asia
BACKGROUND: The association between sedentary behavior and sexual behavior has not been investigated among adolescents. // AIM: The aim of this study was to: (i) investigate the association between leisure-time sedentary behavior and sexual intercourse, and (ii) test for mediation by alcohol consumption, drug use, physical activity, bullying victimization, parental support/ monitoring, loneliness, and depressive symptoms in a large global sample of young adolescents. // METHODS: Data were analyzed from 34,674 adolescents aged 12-15 years participating in the Global School-based Student Health Survey. Participants reported the number of hours spent in leisure-time sedentary behavior on a typical day (8 hours). Data on alcohol consumption, drug use, physical activity, bullying victimization, parental support/monitoring, loneliness, and depressive symptoms were considered as potential mediators. // OUTCOME: Participants reported whether or not they had sexual intercourse in the past 12 months (yes/no). // RESULTS: The prevalence of past 12-month sexual intercourse was 11.9%, whereas the prevalence of 8 hours per day of leisure-time sedentary behavior were 26.7%, 35.6%, 21.4%, 11.5%, and 4.9%, respectively. There was a dose-dependent relationship between sedentary behavior and odds of reporting sexual intercourse: compared with 8 hours/day of sedentary behavior were 1.12 (0.94-1.33), 1.22 (1.01-1.48), 1.34 (1.08-1.66), and 1.76 (1.37-2.27), respectively. There was no significant interaction by sex. The largest proportion of the association between sedentary behavior and sexual intercourse was explained by alcohol use (% mediated 21.2%), with other factors explaining an additional 11.2%. // CLINICAL TRANSLATION: Interventions to reduce leisure-time sedentary and/or alcohol consumption may contribute to a reduction in the proportion of adolescents engaging in sexual intercourse at a young age. The strengths and limitations of this study are the large, representative sample of adolescents from 19 countries. However, the cross-sectional design means causality or temporal associations could not be established. // CONCLUSIONS: In young adolescents, leisure-time sedentary behavior is positively associated with odds of having sexual intercourse in both boys and girls, in a dose-dependent manner. Alcohol consumption seems to be a key mediator of this relationship
Measurement of the neutrino-oxygen neutral-current interaction cross section by observing nuclear deexcitation gamma rays
We report the first measurement of the neutrino-oxygen neutral-current quasielastic (NCQE) cross section gamma It is obtained by observing nuclear deexcitation. rays which follow neutrino-oxygen interactions at the Super-Kamiokande water Cherenkov detector. We use T2K data corresponding to 3.01 x 10(20) protons on target. By selecting only events during the T2K beam window and with well-reconstructed vertices in the fiducial volume, the large background rate from natural radioactivity is dramatically reduced. We observe 43 events in the 4-30 MeV reconstructed energy window, compared with an expectation of 51.0, which includes an estimated 16.2 background events. The background is primarily nonquasielastic neutral-current interactions and has only 1.2 events from natural radioactivity. The flux-averaged NCQE cross section we measure is 1.55 x 10(-38) cm(2) with a 68% confidence interval of (1.22, 2.20) x 10(-38) cm(2) at a median neutrino energy of 630 MeV, compared with the theoretical prediction of 2.01 x 10(-38) cm(2)
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
Effect of insecticide-treated bed net usage on under-five mortality in northern Ghana
BACKGROUND: Although under-five mortality rate seems to be declining in Ghana, the northern part of the country has higher levels of under-five mortality vis-à-vis the national rates. This research examines the correlates of the high under-five mortality among children in the northern part of Ghana, with emphasis on the usage of insecticide-treated bed net (ITN), as recommended by the World Health Organization. METHODS: A total of 3,839 under-five children sourced from the Ghana Demographic and Health Survey—was used for this study. Univariate descriptive statistics was employed to describe the variables used for the empirical estimation. The maximum likelihood estimation technique was used to estimate a logit model in other to determine the effect of insecticide treated bed net usage on under-five mortality. RESULTS: Insecticide-treated bed net usage among children enhances their survival rates. Thus, under-five mortality among children who sleep under treated bed nets is about 18.8% lower than among children who do not sleep under treated bed nets. While health facility delivery was found to reduce to reduce under-five mortality, child bearing among older women is detrimental to the survival of the child. CONCLUSIONS: The study, therefore, recommends that policies targeting reduction in under-five mortality in northern Ghana should consider not mere availability of ITNs in the household, but advocate the usage of these treated nets. The study recommends to the Ministry of Health to extend their services to unreached rural communities to encourage health facility delivery to reduce under-five mortality
Association between sexual orientation and subjective cognitive complaints in the general population in England
There is a scarcity of literature investigating the association between minority sexual orientations and subjective cognitive complaints (SCC). Therefore, the aim of this study was to investigate the association between identifying as a sexual minority and SCC in a large sample of adults from England. The study further aimed to identify the extent to which the association could be explained by several behavioral, psychological and clinical factors. Cross-sectional data from the 2007 Adult Psychiatric Morbidity Survey (APMS) were analyzed. Sexual orientation was dichotomized into heterosexual and sexual minority orientation. SCC referred to subjective concentration and memory complaints. Control variables included sex, age, ethnicity, marital status, education, employment, and income. Influential factors included smoking status, alcohol dependence, perceived stress, the number of stressful life events, depression, any anxiety disorder, sleep problems, and obesity. This study included 7,400 participants (51.4% women; mean [standard deviation] age 46.3 [18.6] years). After adjusting for control variables, sexual minority orientation was positively and significantly associated with subjective concentration (OR = 1.40, 95% CI = 1.12–1.76) but not memory complaints (OR = 1.19, 95% CI = 0.96–1.47). The number of stressful life events, sleep problems and any anxiety disorder explained 13.4%, 11.0% and 10.9% of the association between sexual orientation and subjective concentration complaints, respectively. In this large sample of English adults, identifying as a sexual minority was significantly associated with subjective concentration complaints, while stressful life events, sleep problems, and anxiety explained a large proportion of the association. Targeted interventions towards sexual minority groups to reduce SCC may be warranted
A Phase 1 Trial of pharmacologic interactions between transdermal selegiline and a 4-hour cocaine infusion
BackgroundThe selective MAO-B inhibitor selegiline has been evaluated in clinical trials as a potential medication for the treatment of cocaine dependence. This study evaluated the safety of and pharmacologic interactions between 7 days of transdermal selegiline dosed with patches (Selegiline Transdermal System, STS) that deliver 6 mg/24 hours and 2.5 mg/kg of cocaine administered over 4 hours.MethodsTwelve nondependent cocaine-experienced subjects received deuterium-labeled cocaine-d5 intravenously (IV) 0.5 mg/kg over 10 minutes followed by 2 mg/kg over 4 hours before and after one week of transdermal selegiline 6 mg/24 hours. Plasma and urine were collected for analysis of selegiline, cocaine, catecholamine and metabolite concentrations. Pharmacodynamic measures were obtained.ResultsSelegiline did not change cocaine pharmacokinetic parameters. Selegiline administration increased phenylethylamine (PEA) urinary excretion and decreased urinary MHPG-sulfate concentration after cocaine when compared to cocaine alone. No serious adverse effects occurred with the combination of selegiline and cocaine, and cocaine-induced physiological effects were unchanged after selegiline. Only 1 peak subjective cocaine effects rating changed, and only a few subjective ratings decreased across time after selegiline.ConclusionNo pharmacological interaction occurred between selegiline and a substantial dose of intravenous cocaine, suggesting the combination will be safe in pharmacotherapy trials. Selegiline produced few changes in subjective response to the cocaine challenge perhaps because of some psychoactive neurotransmitters changing in opposite directions
Association between food insecurity and depression among older adults from low‐ and middle‐income countries
Background: To examine the association between self‐reported food insecurity and depression in 34,129 individuals aged ≥50 years from six low‐ and middle‐income countries (LMICs) (China, Ghana, India, Mexico, Russia, and South Africa).
Methods: Cross‐sectional, community‐based, nationally representative data from the WHO Study on global AGEing and adult health (SAGE) were analyzed. Self‐reported past 12‐month food insecurity was assessed with two questions on frequency of eating less and hunger due to lack of food. Questions based on the World Mental Health Survey version of the Composite International Diagnostic Interview were used for the endorsement of past 12‐month DSM‐IV depression. Multivariable logistic regression analysis and meta‐analysis were conducted to assess associations.
Results: In total, 34,129 individuals aged ≥50 years [mean (SD) age, 62.4 (16.0) years; 52.1% females] were included in the analysis. Overall, the prevalence of moderate and severe food insecurity was 6.7% and 5.1%, respectively, while the prevalence of depression was 6.0%. Meta‐analyses based on countrywise estimates showed that overall, moderate food insecurity (vs. no food insecurity) is associated with a nonsignificant 1.69 (95% confidence interval [CI] = 0.82–3.48) times higher odds for depression, while severe food insecurity is significantly associated with 2.43 (95% CI = 1.65–3.57) times higher odds for depression.
Conclusions: In this large representative sample of older adults from six LMICs, those with severe food insecurity were over two times more likely to suffer from depression (compared with no food insecurity). Utilizing lay health counselors and psychological interventions may be effective mechanisms to reduce depression among food‐insecure populations. Interventions to address food insecurity (e.g., supplemental nutrition programs) may reduce depression at the population level but future longitudinal studies are warranted
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