1,287 research outputs found

    Increased tolerance to humans among disturbed wildlife.

    Get PDF
    Human disturbance drives the decline of many species, both directly and indirectly. Nonetheless, some species do particularly well around humans. One mechanism that may explain coexistence is the degree to which a species tolerates human disturbance. Here we provide a comprehensive meta-analysis of birds, mammals and lizards to investigate species tolerance of human disturbance and explore the drivers of this tolerance in birds. We find that, overall, disturbed populations of the three major taxa are more tolerant of human disturbance than less disturbed populations. The best predictors of the direction and magnitude of bird tolerance of human disturbance are the type of disturbed area (urbanized birds are more tolerant than rural or suburban populations) and body mass (large birds are more tolerant than small birds). By identifying specific features associated with tolerance, these results guide evidence-based conservation strategies to predict and manage the impacts of increasing human disturbance on birds

    Japan and Mexico, their past intercourse and present relations

    Full text link
    This item was digitized by the Internet Archive. Thesis (M.A.)--Boston Universityhttps://archive.org/details/japanmexicotheir00fuj

    Characteristics of Oxidative Storage Stability of Canola Fatty Acid Methyl Ester Stabilised with Antioxidants

    Full text link
    The storage effects on the oxidation characteristics of fatty acid methyl ester of canola oil (CME) were investigated in this study.CME stabilised with two antioxidants, i.e.2,6-di-tert-bytyl-p-cresol (BHT) and 6,6-di-tert-butyl-2, 2'-methylendi-p-cresol (BPH), was stored at 20, 40 and 60°C.The oxidation stability data were measured by the Rancimat test method and it was found that both BHT and BPH addition increased the oxidation resistance of the CME. The results showed that when BPH or BHT was added at a concentration of 100 ppm, the oxidation induction period of the neat CME samples increased from 5.53 h to 6.93 hand 6.14 h, respectively. Comparing both antioxidants, BPH proved to be more effective in increasing the oxidation resistance when both antioxidants were added at the same concentration. Furthermore, the oxidation induction timedecreased linearly with the storage time. It was shown that the oxidation occurred rapidly in the first 8 weeks of storage. Later, a kinetic study was undertaken and first-order kinetics were applied to explain the oxidation characteristics of the CME added with antioxidants. This kinetic study focused on exploiting the activation energy values obtained from the Arrheniusequations. Also, the oxidation effects on other quality parameters, including acid value, peroxide value, kinematic viscosity, and water content, were examined

    An efficient computational method for the implementation of a semi-classical instanton approach using discretized path integrals

    Get PDF
    In the present paper, a numerical method for a semi-classical instanton method was examined. We implemented the instanton approach using discretized path integrals. The computational accuracy of the method is controlled by the following two parameters: the imaginary time duration (τ) and the time increment (Δτ), which represents the discretized path integral. To obtain accurate results, a long τ must be used in combination with a short Δτ; however, because the computational cost is virtually proportional to τ/Δτ, the instanton calculations were computationally expensive under these conditions. In the present study, we propose a method that reduces the computational cost and represents long τ instanton trajectories by employing an extended instanton trajectory from calculations based on a short τ. We applied the method to calculate tunnel splitting in a HO2 hydrogen transfer reaction using the double many-body extension IV potential as a validation

    Phosphorylated extracellular signal-regulated kinase up-regulated p53 expression in shikonin-induced HeLa cell apoptosis

    Get PDF
    Background The role of extracellular signal-regulated kinase 1/2 (ERK1/2) in shikonin-induced HeLa cells apoptosis remains vague. This study was to investigate the activation of caspase pathways and the role of ERK1/ 2 in human cervical cancer cells, HeLa, by shikonin. Methods The inhibitory effect of shikonin on the growth of HeLa cells was measured by MTT assay. Fluorescent microscopic analysis of apoptotic cells stained with 4', 6' -oliiamiclino-2-phenylindole C ( DAPI) and Hoechst 33258 was carried out. Caspase-3 and -8 activities were detected using caspase-3 substrate and caspase-8 substrate as substrates, respectively. The protein levels of ERK, p53 and p-ERK were determined by Western blot analysis. Results Shikonin inhibited cell growth in a time- and dose-dependent manner. Caspase-3 and caspase-8 were activated in the apoptotic process and caspase inhibitors effectively reversed shikonin -induced apoptosis. Phosphorylation of ERK resulted in up-regulation of p53 expression, which was blocked by mitogen-activated protein kinase (MEK), inhibitor PD 98059. Conclusion Shikonin induces HeLa cell apoptosis through the ERK, p53 and caspase pathways

    Sex differences in life history, behavior, and physiology along a slow-fast continuum: a meta-analysis

    Get PDF
    Tarka M, Günther A, Niemelae PT, Nakagawa S, Noble DWA. Sex differences in life history, behavior, and physiology along a slow-fast continuum: a meta-analysis. BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY. 2018;72(8): UNSP 132.The pace-of-life syndrome (POLS) hypothesis predicts that behavior and physiology covary with life history. Evidence for such covariation is contradictory, possibly because systematic sources of variation (e.g. sex) have been neglected. Sexes often experience different selection pressures leading to sex-specific allocation between reproduction and self-maintenance, facilitating divergence in life-history. Sex-specific differences in means and possibly variances may therefore play a key role in the POLS framework. We investigate whether sexes differ in means and variances along the fast-slow pace-of-life continuum for life history and physiological and behavioral traits. In addition, we test whether social and environmental characteristics such as breeding strategy, mating system, and study environment explain heterogeneity between the sexes. Using meta-analytic methods, we found that populations with a polygynous mating system or for studies conducted on wild populations, males had a faster pace-of-life for developmental life-history traits (e.g., growth rate), behavior, and physiology. In contrast, adult life-history traits (e.g., lifespan) were shifted towards faster pace-of-life in females, deviating from the other trait categories. Phenotypic variances were similar between the sexes across trait categories and were not affected by mating system or study environment. Breeding strategy did not influence sex differences in variances or means. We discuss our results in the light of sex-specific selection that might drive sex-specific differences in pace-of-life and ultimately POLS

    Superconductivity of the Sr2Ca12Cu24O41Sr_2 Ca_{12} Cu_{24} O_{41} spin ladder system: Are the superconducting pairing and the spin-gap formation of the same origin?

    Full text link
    Pressure-induced superconductivity in a spin-ladder cuprate Sr2_2Ca12_{12}Cu24_{24}O41_{41} has not been studied on a microscopic level so far although the superconductivity was already discovered in 1996. We have improved high-pressure technique with using a large high-quality crystal, and succeeded in studying the superconductivity using 63^{63}Cu nuclear magnetic resonance (NMR). We found that anomalous metallic state reflecting the spin-ladder structure is realized and the superconductivity possesses a s-wavelike character in the meaning that a finite gap exists in the quasi-particle excitation: At pressure of 3.5GPa we observed two excitation modes in the normal state from the relaxation rate T11T_1^{-1}. One gives rise to an activation-type component in T11T_1^{-1}, and the other TT-linear component linking directly with the superconductivity. This gapless mode likely arises from free motion of holon-spinon bound states appearing by hole doping, and the pairing of them likely causes the superconductivity.Comment: to be published in Phys. Rev. Let
    corecore