Detecting the direction of a signal on high-dimensional spheres: Non-null and Le Cam optimality results

We consider one of the most important problems in directional statistics, namely the problem of testing the null hypothesis that the spike direction $\theta$ of a Fisher-von Mises-Langevin distribution on the $p$-dimensional unit hypersphere is equal to a given direction $\theta_0$. After a reduction through invariance arguments, we derive local asymptotic normality (LAN) results in a general high-dimensional framework where the dimension $p_n$ goes to infinity at an arbitrary rate with the sample size $n$, and where the concentration $\kappa_n$ behaves in a completely free way with $n$, which offers a spectrum of problems ranging from arbitrarily easy to arbitrarily challenging ones. We identify various asymptotic regimes, depending on the convergence/divergence properties of $(\kappa_n)$, that yield different contiguity rates and different limiting experiments. In each regime, we derive Le Cam optimal tests under specified $\kappa_n$ and we compute, from the Le Cam third lemma, asymptotic powers of the classical Watson test under contiguous alternatives. We further establish LAN results with respect to both spike direction and concentration, which allows us to discuss optimality also under unspecified $\kappa_n$. To investigate the non-null behavior of the Watson test outside the parametric framework above, we derive its local asymptotic powers through martingale CLTs in the broader, semiparametric, model of rotationally symmetric distributions. A Monte Carlo study shows that the finite-sample behaviors of the various tests remarkably agree with our asymptotic results.Comment: 47 pages, 4 figure

Evidence of Yersinia pestis DNA from fleas in an endemic plague area of Zambia

BACKGROUND: Yersinia pestis is a bacterium that causes plague which infects a variety of mammals throughout the world. The disease is usually transmitted among wild rodents through a flea vector. The sources and routes of transmission of plague are poorly researched in Africa, yet remains a concern in several sub-Saharan countries. In Zambia, the disease has been reported on annual basis with up to 20 cases per year, without investigating animal reservoirs or vectors that may be responsible in the maintenance and propagation of the bacterium. In this study, we undertook plague surveillance by using PCR amplification of the plasminogen activator gene in fleas. FINDINGS: Xenopsylla species of fleas were collected from 83 rodents trapped in a plague endemic area of Zambia. Of these rodents 5 had fleas positive (6.02%) for Y. pestis plasminogen activator gene. All the Y. pestis positive rodents were gerbils. CONCLUSIONS: We conclude that fleas may be responsible in the transmission of Y. pestis and that PCR may provide means of plague surveillance in the endemic areas of Zambia

Bats in the anthropogenic matrix: Challenges and opportunities for the conservation of chiroptera and their ecosystem services in agricultural landscapes

Intensification in land-use and farming practices has had largely negative effects on bats, leading to population declines and concomitant losses of ecosystem services. Current trends in land-use change suggest that agricultural areas will further expand, while production systems may either experience further intensification (particularly in developing nations) or become more environmentally friendly (especially in Europe). In this chapter, we review the existing literature on how agricultural management affects the bat assemblages and the behavior of individual bat species, as well as the literature on provision of ecosystem services by bats (pest insect suppression and pollination) in agricultural systems. Bats show highly variable responses to habitat conversion, with no significant change in species richness or measures of activity or abundance. In contrast, intensification within agricultural systems (i.e., increased agrochemical inputs, reduction of natural structuring elements such as hedges, woods, and marshes) had more consistently negative effects on abundance and species richness. Agroforestry systems appear to mitigate negative consequences of habitat conversion and intensification, often having higher abundances and activity levels than natural areas. Across biomes, bats play key roles in limiting populations of arthropods by consuming various agricultural pests. In tropical areas, bats are key pollinators of several commercial fruit species. However, these substantial benefits may go unrecognized by farmers, who sometimes associate bats with ecosystem disservices such as crop raiding. Given the importance of bats for global food production, future agricultural management should focus on “wildlife-friendly” farming practices that allow more bats to exploit and persist in the anthropogenic matrix so as to enhance provision of ecosystem services. Pressing research topics include (1) a better understanding of how local-level versus landscape-level management practices interact to structure bat assemblages, (2) the effects of new pesticide classes and GM crops on bat populations, and (3) how increased documentation and valuation of the ecosystem services provided by bats could improve attitudes of producers toward their conservation

Physical activity and sedentary behavior in people with major depressive disorder: A systematic review and meta-analysis

BACKGROUND: Low levels of physical activity (PA) and sedentary behavior (SB) are independent risk factors for cardiovascular disease and premature mortality in people with major depressive disorder (MDD). AIMS: Investigate levels of PA and SB and their predictors in people with MDD. METHODS: Electronic databases were searched from inception till 04/2016 for articles measuring PA and SB with a self-report questionnaire (SRQ) or objective measure (e.g. accelerometer) in people with MDD. Random-effects meta-analyses and meta-regression analyses were conducted. RESULTS: Twenty-four eligible studies were identified including 2901 people with MDD (78.4% female, mean age=54 years; range: 21-77 years). People with MDD spent 126.0min (95%CI=91.9-160.1) per day engaging in all types of PA and spent 8.5hours (95%CI=7.51-9.62) during their waking day being sedentary. Compared to controls, people with MDD spent less time in total PA (SMD=-0.25, 95%CI=-0.03 to 0.15) and moderate to vigorous PA (SMD=-0.30, 95%CI=-0.40 to 0.21) and engaged in higher levels of SB (SMD=0.09, 95%CI=0.01-0.18). The proportion of people with MDD not meeting the recommended PA guidelines was 67.8% (n=13 studies), which was higher in studies relying on objective versus self-report measures (85.7% v 62.1%, p=0.04). People with MDD were more likely than controls to not meeting the recommended PA guidelines (OR = 1.50, 95%CI = 1.10–2.10). LIMITATIONS: Heterogeneity was evident in most analyses. CONCLUSIONS: Adults with MDD engage in low levels of PA and high levels of SB. PA and SB are independent predictors of mortality, therefore, future lifestyle interventions targeting both the prevention of SB and adoption and maintenance of PA are warranted.publisher: Elsevier articletitle: Physical activity and sedentary behavior in people with major depressive disorder: A systematic review and meta-analysis journaltitle: Journal of Affective Disorders articlelink: http://dx.doi.org/10.1016/j.jad.2016.10.050 content_type: article copyright: © 2016 Elsevier B.V. All rights reserved.status: publishe

High‐Voltage Photogeneration Exclusively via Aggregation‐Induced Triplet States in a Heavy‐Atom‐Free Nonplanar Organic Semiconductor

The electron–hole recombination kinetics of organic photovoltaics (OPVs) are known to be sensitive to the relative energies of triplet and charge-transfer (CT) states. Yet, the role of exciton spin in systems having CT states above 1.7 eV—like those in near-ultraviolet-harvesting OPVs—has largely not been investigated. Here, aggregation-induced room-temperature intersystem crossing (ISC) to facilitate exciton harvesting in OPVs having CT states as high as 2.3 eV and open-circuit voltages exceeding 1.6 V is reported. Triplet excimers from energy-band splitting result in ultrafast CT and charge separation with nonradiative energy losses of <250 meV, suggesting that a 0.1 eV driving force is sufficient for charge separation, with entropic gain via CT state delocalization being the main driver for exciton dissociation and generation of free charges. This finding can inform engineering of next-generation active materials and films for near-ultraviolet OPVs with open-circuit voltages exceeding 2 V. Contrary to general belief, this work reveals that exclusive and efficient ISC need not require heavy-atom-containing active materials. Molecular aggregation through thin-film processing provides an alternative route to accessing 100% triplet states on photoexcitation

Frequency of fiber-rich food intake and associated factors in a Southern Brazilian population Freqüência do consumo de alimentos fontes de fibras e fatores associados em população do Sul do Brasil

The objective of this study was to verify the frequency of fiber-rich food intake and evaluate its association with socioeconomic, demographic and behavioral characteristics. A city representative sample was selected and 3,993 subjects (> 10 years) were interviewed. The study used the Block Screening Questionnaire. A majority of subjects - 65.6% (95%CI: 64.2-67.1) - presented an inadequate intake frequency. Adjusted analysis for the overall sample showed an increased risk of inadequate frequency among men, adolescents, people of lower socioeconomic levels, current smokers, those insufficiently active and those having fewer than four daily meals. Age group-stratified analysis showed that among adolescents, living alone was a risk factor; for adults, risk factors were sex (male), current smoker, insufficiently active and fewer than four daily meals and; among the elderly they were male and being a current smoker. A lower socioeconomic level was associated to the outcome in all groups. Although the inadequate frequency of intake is very common in this population, teenagers are at a higher risk, pointing to a need for public health actions targeting this particular age group.<br>Verificar a freqüência do consumo de alimentos fontes de fibras e avaliar sua associação com características sócio-econômicas, demográficas e comportamentais. Foi selecionada amostra representativa da cidade e 3.993 indivíduos (> 10 anos) foram entrevistados. Foi utilizado o instrumento Block Screening. A maioria da amostra, 65,6% (IC95%: 64,2-67,1), mostrou freqüência inadequada de consumo. A análise ajustada para amostra global mostrou risco aumentado de freqüência inadequada entre homens, adolescentes, de menor nível sócio-econômico, fumante atual, insuficientemente ativo e aqueles que faziam menos de 4 refeições/dia. A análise por faixa etária mostrou que entre adolescentes, morar sozinho foi um fator de risco; entre adultos, homens, fumantes, insuficientemente ativos e que realizavam menos de 4 refei��ões/dia; e, entre idosos, somente homens e fumantes. O menor nível sócio-econômico associou-se ao desfecho em todos os grupos. Ressalta-se que embora a população apresente alto porcentual do desfecho, chama atenção os adolescentes, sugerindo medidas prioritárias nesta faixa etária