1,074 research outputs found
The Importance of Early Successional Habitats to Rare, Restricted-range, and Endangered Birds in the Ecuadorian Andes
Since the mid-1980s, exhausted pastures in Ecuador have been increasingly abandoned, allowing forest regeneration. At approximately 2,200 m in the Tandayapa valley I surveyed four abandoned pastures to evaluate their use by birds. Each former pasture represented a different age of vegetation maturity. The number of bird species recorded in each successively older abandoned pasture increased but only half the number of species recorded in the undisturbed forest site was recorded in the most mature pasture. However, at least four restricted-range bird species were recorded in a single pasture. As pastures rapidly convert to secondary forest, more bird species and rarer bird species use them, even in highly disturbed areas where surrounding pristine forest constitutes less than 10% of local forest cover. Conservation efforts should then be directed toward them
Constant net-time headway as key mechanism behind pedestrian flow dynamics
We show that keeping a constant lower limit on the net-time headway is the
key mechanism behind the dynamics of pedestrian streams. There is a large
variety in flow and speed as functions of density for empirical data of
pedestrian streams, obtained from studies in different countries. The net-time
headway however, stays approximately constant over all these different data
sets. By using this fact, we demonstrate how the underlying dynamics of
pedestrian crowds, naturally follows from local interactions. This means that
there is no need to come up with an arbitrary fit function (with arbitrary fit
parameters) as has traditionally been done. Further, by using not only the
average density values, but the variance as well, we show how the recently
reported stop-and-go waves [Helbing et al., Physical Review E, 75, 046109]
emerge when local density variations take values exceeding a certain maximum
global (average) density, which makes pedestrians stop.Comment: 7 pages, 7 figure
Reaction Time of a Group of Physics Students
The reaction time of a group of students majoring in Physics is reported
here. Strong co-relation between fatigue, reaction time and performance have
been seen and may be useful for academicians and administrators responsible of
working out time-tables, course structures, students counsellings etc.Comment: 10 pages, 4 figure
Phase Coherence and Superfluid-Insulator Transition in a Disordered Bose-Einstein Condensate
We have studied the effects of a disordered optical potential on the
transport and phase coherence of a Bose-Einstein condensate (BEC) of 7Li atoms.
At moderate disorder strengths (V_D), we observe inhibited transport and
damping of dipole excitations, while in time-of-flight images, random but
reproducible interference patterns are observed. In-situ images reveal that the
appearance of interference is correlated with density modulation, without
complete fragmentation. At higher V_D, the interference contrast diminishes as
the BEC fragments into multiple pieces with little phase coherence.Comment: 4 pages, 5 figures, distortions in figures 1 and 4 have been fixed in
version 3. This paper has been accepted to PR
Validation of Inverse Seasonal Peak Mortality in Medieval Plagues, Including the Black Death, in Comparison to Modern Yersinia pestis-Variant Diseases
Background: Recent studies have noted myriad qualitative and quantitative inconsistencies between the medieval Black Death (and subsequent ‘‘plagues’’) and modern empirical Y. pestis plague data, most of which is derived from the Indian and Chinese plague outbreaks of A.D. 1900615 years. Previous works have noted apparent differences in seasonal mortality peaks during Black Death outbreaks versus peaks of bubonic and pneumonic plagues attributed to Y. pestis infection, but have not provided spatiotemporal statistical support. Our objective here was to validate individual observations of this seasonal discrepancy in peak mortality between historical epidemics and modern empirical data. Methodology/Principal Findings: We compiled and aggregated multiple daily, weekly and monthly datasets of both Y. pestis plague epidemics and suspected Black Death epidemics to compare seasonal differences in mortality peaks at a monthly resolution. Statistical and time series analyses of the epidemic data indicate that a seasonal inversion in peak mortality does exist between known Y. pestis plague and suspected Black Death epidemics. We provide possible explanations for this seasonal inversion. Conclusions/Significance: These results add further evidence of inconsistency between historical plagues, including the Black Death, and our current understanding of Y. pestis-variant disease. We expect that the line of inquiry into the disputed cause of the greatest recorded epidemic will continue to intensify. Given the rapid pace of environmental change in th
Photoassociation of a Bose-Einstein Condensate near a Feshbach Resonance
We measure the effect of a magnetic Feshbach resonance (FR) on the rate and
light-induced frequency shift of a photoassociation resonance in ultracold
Li. The photoassociation-induced loss rate coefficient, , depends
strongly on magnetic field, varying by more than a factor of 10 for fields
near the FR. At sufficiently high laser intensities, for a thermal gas
decreases with increasing intensity, while saturation is observed for the first
time in a Bose-Einstein condensate. The frequency shift is also strongly
field-dependent and exhibits an anomalous blue-shift for fields just below the
FR.Comment: 4 pages, 4 figures. v2: updated comparison with theory; added
references; added tick marks to Fig. 1 inset. To be published in Phys. Rev.
Letter
Draft Genome Sequence of Venenivibrio stagnispumantis CP.B2T, Isolated from Champagne Pool, Waiotapu, Aotearoa-New Zealand.
Venenivibrio stagnispumantis strain CP.B2T is a thermophilic, chemolithoautotrophic bacterium from the family Hydrogenothermaceae (phylum Aquificota), isolated from Champagne Pool in the Waiotapu geothermal field, Aotearoa-New Zealand. The genome consists of 1.73 Mbp in 451 contigs with a 30.8 mol% G+C content
The determinants of hotels' marketing managers' green marketing behaviour
Little is known about the factors underlying the pro-environmental behaviour of marketing managers. This paper explores the determinants of green marketing practices in the Red Sea hotel sector in Egypt. The research model assesses green marketing practices against the personal and organisational values of the marketing managers, together with a range of organisational and demographic variables expected to influence hotels' environmental behaviour. From a valid sample of 89 marketing managers responsible for 194 hotels, it was found that organisational contextual variables, and in particular targeting Western tourists, being affiliated to an international hotel chain and the marketers' own demographics, including age, academic subject studied and gender, were the best predictors of more proactive green marketing. Personal environmental values did not explain the pro-environmental behaviour of marketers, and the organisational environmental values that had explained part of their ethical behaviour had resulted from voluntarism rather than utilitarian or conformance-based values. Government policies also appeared to be ineffective determinants. The implications for green marketing practices are also discussed. © 2010 Taylor & Francis
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