1,726 research outputs found

    Emerging vistas of Remote Sensing Tools in Pollination Studies

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    With the growth of information and technology across the globe, remote sensing applications find a place in the ecological studies of pollinators. The utilization of remote sensing tools in understanding the ecosystem services rendered by the bee pollinators is reviewed here. We discussed how radar and radio telemetry techniques helps to track individual bees, their foraging behaviour and density in relation to altered phenology of flowering crops in a landscape. Role of satellite imagery tools in studying characterizing a landscape affected by anthropogenic factors was discussed.  Monitoring invasive bee species that cause a threat to native bee fauna was explored. We explained the utilization of unmanned aerial vehicles to map the floral resource that influence the density and incidence of pollinators. Remote sensing tools used to measure sequence of pollination events was discussed

    Gap phase regeneration of tree species of differing successional status in a humid tropical forest of Kerala, India

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    Germination, establishment and growth of seedlings of tree species Palaquium ellipticum (primary), Actinodaphne malabarica (late secondary) and Macaranga peltata (early secondary) were studied in a humid tropical forest at Nelliampathy, in the Western Ghats of Kerala. While the primary species completed its germination within a brief period of 1.5 months, at the other extreme, early secondary species showed slow germination extending for about 5 months, the late secondary species falling in between. Although, all the species studied showed higher establishment and growth under gaps, the early secondary species were more responsive compared to the primary species. Primary species showed better establishment in undisturbed sites and natural gaps than under selection felled gaps; the reverse was true for late and early secondary species. Survival of seedlings increased with gap size, but sharply declined with gap age. Shoot/root ratio was consistently higher in the early secondary species than in the primary species

    Vitamins and Perinatal Outcomes Among HIV-Negative Women in Tanzania.

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    Prematurity and low birth weight are associated with high perinatal and infant mortality, especially in developing countries. Maternal micronutrient deficiencies may contribute to these adverse outcomes. In a double-blind trial in Dar es Salaam, Tanzania, we randomly assigned 8468 pregnant women (gestational age of fetus, 12 to 27 weeks) who were negative for human immunodeficiency virus infection to receive daily multivitamins (including multiples of the recommended dietary allowance) or placebo. All the women received prenatal supplemental iron and folic acid. The primary outcomes were low birth weight (<2500 g), prematurity, and fetal death. The incidence of low birth weight was 7.8% among the infants in the multivitamin group and 9.4% among those in the placebo group (relative risk, 0.82; 95% confidence interval [CI], 0.70 to 0.95; P=0.01). The mean difference in birth weight between the groups was modest (67 g, P<0.001). The rates of prematurity were 16.9% in the multivitamin group and 16.7% in the placebo group (relative risk, 1.01; 95% CI, 0.91 to 1.11; P=0.87), and the rates of fetal death were 4.3% and 5.0%, respectively (relative risk, 0.87; 95% CI, 0.72 to 1.05; P=0.15). Supplementation reduced both the risk of a birth size that was small for gestational age (<10th percentile; 10.7% in the multivitamin group vs. 13.6% in the placebo group; relative risk, 0.77; 95% CI, 0.68 to 0.87; P<0.001) and the risk of maternal anemia (hemoglobin level, <11 g per deciliter; relative risk, 0.88; 95% CI, 0.80 to 0.97; P=0.01), although the difference in the mean hemoglobin levels between the groups was small (0.2 g per deciliter, P<0.001). Multivitamin supplementation reduced the incidence of low birth weight and small-for-gestational-age births but had no significant effects on prematurity or fetal death. Multivitamins should be considered for all pregnant women in developing countries. (ClinicalTrials.gov number, NCT00197548 [ClinicalTrials.gov].)

    Determinants of Effective Population Size for Loci with Different Modes of Inheritance

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    Here we report an assessment of the determinants of effective population size (Ne) in species with overlapping generations. Specifically, we used a stochastic demographic model to investigate the influence of different life-history variables on Ne/N (where N = population census number) and the influence of sex differences in life-history variables on Ne for loci with dif¬ferent modes of inheritance. We applied an individual-based modeling approach to two datasets: one from a natural popu¬lation of savannah baboons (Papio cynocephalus) in the Amboseli basin of southern Kenya and one from a human tribal pop¬ulation (the Gainj of Papua New Guinea). Simulation-based estimates of Ne/N averaged 0.329 for the Amboseli baboon population (SD = 0.116, 95% CI = 0.172 – 0.537) and 0.786 for the Gainj (SD = 0.184, 95% CI = 0.498 – 1.115). Although variance in male fitness had a substantial impact on Ne/N in each of the two primate populations, ratios of Ne values for au¬tosomal and sex-linked loci exhibited no significant departures from Poisson-expected values. In each case, similarities in sex-specific Ne values were attributable to the unexpectedly high variance in female fitness. Variance in male fitness resulted primarily from age-dependent variance in reproductive success, whereas variance in female fitness resulted primarily from stochastic variance in survival during the reproductive phase

    Chi8: a GPU program for detecting significant interacting SNPs with the Chi-square 8-df test

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    BACKGROUND: Determining interacting SNPs in genome-wide association studies is computationally expensive yet of considerable interest in genomics. FINDINGS: We present a program Chi8 that calculates the Chi-square 8 degree of freedom test between all pairs of SNPs in a brute force manner on a Graphics Processing Unit. We analyze each of the seven WTCCC genome-wide association studies that have about 5000 total case and controls and 400,000 SNPs in an average of 9.6 h on a single GPU. We also study the power, false positives, and area under curve of our program on simulated data and provide a comparison to the GBOOST program. Our program source code is freely available from http://www.cs.njit.edu/usman/Chi8

    Antiferromagnetic ordering in the Kondo lattice system Yb2_2Fe3_3Si5_5

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    Compounds belonging to the R2_2Fe3_3Si5_5 series exhibit unusual superconducting and magnetic properties. Although a number of studies have been made on the first reentrant antiferromagnet superconductor Tm2_2Fe3_3Si5_5, the physical properties of Yb2_2Fe3_3Si5_5 are largely unexplored. In this work, we attempt to provide a comprehensive study of bulk properties such as, resistivity, susceptibility and heat-capacity of a well characterized polycrystalline Yb2_2Fe3_3Si5_5. Our measurements indicate that Yb3+^{3+} moments order antiferromagnetically below 1.7 K. Moreover, the system behaves as a Kondo lattice with large Sommerfeld coefficient (γ\gamma) of 0.5~J/Yb mol K2^{2} at 0.3 K, which is well below TN_N. The absence of superconductivity in Yb2_2Fe3_3Si5_5 down to 0.3 K at ambient pressure is attributed to the presence of the Kondo effect.Comment: 10 pages, 3 figures, tex document. A fuller version has appeared in PRB. Here we have omitted the figures showing the crystal structure and the fitting of the X-ray pattern. Also the table with the lattice parameters obtained from fitting has been remove

    A Pathwise Ergodic Theorem for Quantum Trajectories

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    If the time evolution of an open quantum system approaches equilibrium in the time mean, then on any single trajectory of any of its unravelings the time averaged state approaches the same equilibrium state with probability 1. In the case of multiple equilibrium states the quantum trajectory converges in the mean to a random choice from these states.Comment: 8 page

    Crystal Symmetry Lowering in Chiral Multiferroic Ba3_3TaFe3_3Si2_2O14_{14} observed by X-Ray Magnetic Scattering

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    Chiral multiferroic langasites have attracted attention due to their doubly-chiral magnetic ground state within an enantiomorphic crystal. We report on a detailed resonant soft X-ray diffraction study of the multiferroic Ba3_3TaFe3_3Si2_2O14_{14} at the Fe L2,3L_{2,3} and oxygen KK edges. Below TNT_N (≈27K\approx27K) we observe the satellite reflections (0,0,τ)(0,0,\tau), (0,0,2τ)(0,0,2\tau), (0,0,3τ)(0,0,3\tau) and (0,0,1−3τ)(0,0,1-3\tau) where τ≈0.140±0.001\tau \approx 0.140 \pm 0.001. The dependence of the scattering intensity on X-ray polarization and azimuthal angle indicate that the odd harmonics are dominated by the out-of-plane (c^\mathbf{\hat{c}}-axis) magnetic dipole while the (0,0,2τ)(0,0,2\tau) originates from the electron density distortions accompanying magnetic order. We observe dissimilar energy dependences of the diffraction intensity of the purely magnetic odd-harmonic satellites at the Fe L3L_3 edge. Utilizing first-principles calculations, we show that this is a consequence of the loss of threefold crystal symmetry in the multiferroic phase
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