Search results for "fragmentation"

Determinants of jaguar occupancy at the northern range edge

2020

Identifying factors promoting jaguar (Panthera onca) occupancy is crucial for planning effective conservation and management actions that can contribute to long-term population viability. We used camera-trapping and modeled factors affecting detection and occupancy for jaguars in Sonora at 149 sites during August-November 2008 and 2009. We measured 24 covariates presumed to affect detection (n = 6) and occupancy (n = 18) at camera sites, including sampling period and various habitat characteristics. We obtained 29 jaguar detections at 19 sites (naive occupancy = 0.12) in 5455 trap-days of effort. Jaguar detectability (p = 0.16 +/- 0.05) was negatively affected by human presence and varied b…

Factors influencing the extent of inbreeding depression: an example from scots pine

1999

Detailed studies suggest that the level of inbreeding depression may vary between populations. In a study of Scots pine from Finland, the level of inbreeding depression was much lower in northern than in southern populations. We have examined theoretically whether population genetic factors, such as the level of selfing, intensity of selection against heterozygotes or homozygotes, level of mutation, a bottleneck, finite population size, or the level of polyembryony could account for this difference. Higher selfing or stronger selection against heterozygotes in the north, both at biologically reasonable levels, appear to produce changes consistent with the observed differences and we conside…

Inclusive photoproduction of bottom quarks for low and medium p T in the general-mass variable-flavour-number scheme

2016

We present predictions for b-quark production in photoprodcution and compare with experimental data from HERA. Our theoretical predictions are obtained at next-to-leading-order in the general-mass variable-flavor-number scheme, an approach which takes into account the finite mass of the b quarks. We use realistic evolved nonperturbative fragmentation functions obtained from fits to e+e- data. We find in general good agreement of data with both the GM-VFNS and the FFNS calculations, while the more precise ZEUS data seem to prefer the GM-VFNS predictions.

Muon-electron lepton-flavor-violating transitions : Shell-model calculations of transitions in 27Al

2018

In this paper we present the results of large-scale shell-model calculations of muon-to-electron lepton-flavorviolating transitions for the case of the target nucleus 27Al. We extend the previous shell-model calculations, done in the sd model space, by including also the p orbitals in order to see whether the negative-parity states produce any significant effect in the conversion rate. The analysis of the results shows the dominance of coherent transitions mediated by isovector operators and going by the ground state of the target, with practically null influence of excited positive- or negative-parity states. peerReviewed

APOPTOTIC ANALYSIS OF CUMULUS CELLS FOR THE SELECTION OF COMPETENT OOCYTES TO BE FERTILIZED BY INTRACYTOPLASMIC SPERM INJECTION (ICSI)

2015

Oocyte quality is one of the main factors for the success of in vitro fertilization protocols. Apoptosis is known to affect oocyte quality and may impair subsequent embryonic development and implantation. The aim of this study was to investigate the apoptosis rate of single and pooled cumulus cells of cumulus cell–oocyte complexes (COCs), as markers of oocyte quality, prior to intracytoplasmatic sperm injection (ICSI).We investigated the apoptosis rate by TUNEL assay (DNA fragmentation) and caspase-3 immunoassay of single and pooled cumulus cells of COCs. The results showed that DNA fragmentation in cumulus cells was remarkably lower in patients who achieved a pregnancy than in those who di…

Antioxidants in ICSI

2013

Male factor infertility can be caused by reasons, either related or not with total sperm production. Among causes of male infertility in cases of normal sperm count and motility, oxidative stress is one of the most relevant processes influencing fertility in vivo or in assisted reproduction treatments’ results. This chapter provides the most updated information regarding the oxidative stress situation in sperm and the relevance of antioxidants use in intracytoplasmic sperm injection results.

Genetic diversity in the wild : cyclic population dynamics and population isolation

2013

Comparing the Climatic and Landscape Risk Factors for Lyme Disease Cases in the Upper Midwest and Northeast United States

2020

Lyme disease, recognized as one of the most important vector-borne diseases worldwide, has been increasing in incidence and spatial extend in United States. In the Northeast and Upper Midwest, Lyme disease is transmitted by Ixodes scapularis. Currently, many studies have been conducted to identify factors influencing Lyme disease risk in the Northeast, however, relatively few studies focused on the Upper Midwest. In this study, we explored and compared the climatic and landscape factors that shape the spatial patterns of human Lyme cases in these two regions, using the generalized linear mixed models. Our results showed that climatic variables generally had opposite correlations with Lyme d…

Upper Caraş River (Danube watershed) fish populations fragmentation – technical rehabilitation proposal

2017

Abstract We propose a technical solution for fish movement based on the flow of water over a spill threshold. Such barriers are common in the Danube system. The proposed system has a range of operating components which are easily detachable from the spill threshold, are resistant to corrosion and will not harm the fish. In fact, if designed to complement swimming abilities of target fish, it should provide adequate passage for both adults and juveniles. If implemented correctly, the design may offer a solution to help displaced fish recolonize upstream habitats.

Landscape Ecological Structure in the Eastern Part of the North Vidzeme Biosphere Reserve, Latvia

2008

Landscape Ecological Structure in the Eastern Part of the North Vidzeme Biosphere Reserve, Latvia Latvia is a country where the forest area has increased and habitat fragmentation has reversed compared with many other European countries. In order to examine the effect of this expansion on biodiversity, vegetation maps dating from 2002 and the years 1930-1936 were used for comparative landscape structure analyses while archive materials from forest plans, and data from the national forest management database were used for land use analysis. Four landscape ecoregions in the eastern side of the North Vidzeme Biosphere Reserve were selected for analysis. Landscape structure indicators derived f…