689 research outputs found
Design matters : an evaluation of the impact of small man-made forest clearings on tropical bats using a before-after-control-impact design
In recent years, large clearings (>1000 ha) accounted for gradually smaller amounts of total annual deforestation
in the Brazilian Amazon, whereas the proportion of small clearings (<50 ha) nowadays represents
more than 80% of annual deforestation. Despite the ubiquity of small clearings in fragmented
Amazonian landscapes, most fragmentation research has focused on the effects of large-scale deforestation,
leading to a poor understanding of the impacts of smaller barriers on Amazonian vertebrates. We
capitalized on the periodical re-isolation of experimental forest fragments at the Biological Dynamics
of Forest Fragments Project in the Central Amazon as a before-after-control-impact experiment to investigate
the short-term effects of small clearings on bat assemblages. Over the course of three years we
sampled six control sites in continuous forest, the interiors and edges of eight forest fragments as well
as eight sites in the surrounding matrix. Sampling took place both before and after the experimental
manipulation (clearing of a 100 m wide strip of regrowth around each fragment), resulting in ~4000
bat captures. Species were classified as old-growth specialists and habitat generalists according to their
habitat affinities and a joint species distribution modeling framework was used to investigate the effect
of fragment re-isolation on species occupancy. Following fragment re-isolation, species richness declined
in all habitats other than fragment edges and, although responses were idiosyncratic, this decline was
more pronounced for forest specialist than for generalist species. Additionally, fragment re-isolation
led to a reduction in the similarity between assemblages in modified habitats (fragment interiors, edges
and matrix) and continuous forest. Sampling of controls in continuous forest both prior to and after reisolation
revealed that much of the variation in bat species occupancy between sampling periods did not
arise from fragment re-isolation but rather reflected natural spatiotemporal variability. This emphasizes
the need to sample experimental controls both before and after experimental manipulation and suggests
caution in the interpretation of results from studies in which the effects of habitat transformations are
assessed based solely on data collected using space-for-time substitution approaches
Dark spinor models in gravitation and cosmology
We introduce and carefully define an entire class of field theories based on
non-standard spinors. Their dominant interaction is via the gravitational field
which makes them naturally dark; we refer to them as Dark Spinors. We provide a
critical analysis of previous proposals for dark spinors noting that they
violate Lorentz invariance. As a working assumption we restrict our analysis to
non-standard spinors which preserve Lorentz invariance, whilst being non-local
and explicitly construct such a theory. We construct the complete
energy-momentum tensor and derive its components explicitly by assuming a
specific projection operator. It is natural to next consider dark spinors in a
cosmological setting. We find various interesting solutions where the spinor
field leads to slow roll and fast roll de Sitter solutions. We also analyse
models where the spinor is coupled conformally to gravity, and consider the
perturbations and stability of the spinor.Comment: 43 pages. Several new sections and details added. JHEP in prin
Design matters : an evaluation of the impact of small man-made forest clearings on tropical bats using a before-after-control-impact design
In recent years, large clearings (>1000 ha) accounted for gradually smaller amounts of total annual deforestation
in the Brazilian Amazon, whereas the proportion of small clearings (<50 ha) nowadays represents
more than 80% of annual deforestation. Despite the ubiquity of small clearings in fragmented
Amazonian landscapes, most fragmentation research has focused on the effects of large-scale deforestation,
leading to a poor understanding of the impacts of smaller barriers on Amazonian vertebrates. We
capitalized on the periodical re-isolation of experimental forest fragments at the Biological Dynamics
of Forest Fragments Project in the Central Amazon as a before-after-control-impact experiment to investigate
the short-term effects of small clearings on bat assemblages. Over the course of three years we
sampled six control sites in continuous forest, the interiors and edges of eight forest fragments as well
as eight sites in the surrounding matrix. Sampling took place both before and after the experimental
manipulation (clearing of a 100 m wide strip of regrowth around each fragment), resulting in ~4000
bat captures. Species were classified as old-growth specialists and habitat generalists according to their
habitat affinities and a joint species distribution modeling framework was used to investigate the effect
of fragment re-isolation on species occupancy. Following fragment re-isolation, species richness declined
in all habitats other than fragment edges and, although responses were idiosyncratic, this decline was
more pronounced for forest specialist than for generalist species. Additionally, fragment re-isolation
led to a reduction in the similarity between assemblages in modified habitats (fragment interiors, edges
and matrix) and continuous forest. Sampling of controls in continuous forest both prior to and after reisolation
revealed that much of the variation in bat species occupancy between sampling periods did not
arise from fragment re-isolation but rather reflected natural spatiotemporal variability. This emphasizes
the need to sample experimental controls both before and after experimental manipulation and suggests
caution in the interpretation of results from studies in which the effects of habitat transformations are
assessed based solely on data collected using space-for-time substitution approaches
Author correction : a global database for metacommunity ecology, integrating species, traits, environment and space
Correction to: Scientific Data https://doi.org/10.1038/s41597-019-0344-7, published online 08 January 202
Author correction : a global database for metacommunity ecology, integrating species, traits, environment and space
Correction to: Scientific Data https://doi.org/10.1038/s41597-019-0344-7, published online 08 January 202
Essential fatty acids for premenstrual syndrome and their effect on prolactin and total cholesterol levels: a randomized, double blind, placebo-controlled study
<p>Abstract</p> <p>Objective</p> <p>To evaluate the effectiveness and safety of polyunsaturated fatty acids for the treatment of the premenstrual syndrome (PMS) using a graded symptom scale and to assess the effect of this treatment on basal plasma levels of prolactin and total cholesterol.</p> <p>Methods</p> <p>A randomized, double-blind, placebo-controlled study was conducted with 120 women with PMS divided into three groups and treated with 1 or 2 grams of the medication or placebo. Symptoms were recorded over a 6-month period using the Prospective Record of the Impact and Severity of Menstruation (PRISM) calendar. Total cholesterol and prolactin levels were measured. Analysis of variance (ANOVA), Pearson's chi-square test, Wilcoxon's nonparametric signed-rank test for paired samples and the Mann-Whitney nonparametric test for independent samples were used in the statistical analysis.</p> <p>Results</p> <p>There were no differences in age, marital status, schooling or ethnicity between the groups. In the group treated with 1 gram of the medication, a significant reduction was found when the median PRISM score recorded in the luteal phase at baseline (99) was compared with the median score recorded in the 3<sup>rd </sup>month (58) and in the 6<sup>th </sup>month of evaluation (35). In the 2-gram group, these differences were even more significant (baseline score: 98; 3<sup>rd </sup>month: 48; 6<sup>th </sup>month: 28). In the placebo group, there was a significant reduction at the 3<sup>rd </sup>but not at the 6<sup>th </sup>month (baseline: 96.5; 3<sup>rd </sup>month: 63.5; 6<sup>th </sup>month: 62). The difference between the phases of the menstrual cycle was greater in the 2-gram group compared to the group treated with 1 gram of the medication. There were no statistically significant differences in prolactin or total cholesterol levels between baseline values and those recorded after six months of treatment.</p> <p>Conclusion</p> <p>The difference between the groups using the medication and the placebo group with respect to the improvement in symptomatology appears to indicate the effectiveness of the drug. Improvement in symptoms was higher when the 2-gram dose was used. This medication was not associated with any changes in prolactin or total cholesterol levels in these women.</p
Technical attainment, practical success and practical knowledge: hermeneutical bases for child nursing care
Adherence to best care practices in normal birth: construction and validation of an instrument
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
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