3,971 research outputs found
Life-history evolution in harvested populations: the role of natural predation
Models and experiments of the evolution of age- and/or size-at-maturation in response to population harvesting have consistently shown that selective harvesting of older and larger individuals can cause earlier maturation. These predictions, however, are all based on single-species considerations and thus crucially neglect the selective forces caused or mediated by species interactions. Here we develop simple models of phenotypic evolution of age-at-first-reproduction in a prey population subject to different types of predation and harvesting. We show that, in the presence of natural predation, the potential evolutionary response of age-at-first-reproduction to population harvesting is ambiguous: harvesting can cause either earlier or later maturation depending on the type of predator interaction and its strength relative to the fishing pressure. The counterintuitive consequences of harvesting result from the indirect effects that harvesting of a prey population has on the selection pressure exerted by its natural predator, since this selection pressure itself typically depends on prey density. If harvest rates are high, the direct selection pressures considered in classical analyses prevail and harvesting decreases the age-at-first-reproduction, whereas at lower harvest rates the indirect, inter-specifically mediated effects of harvesting can qualitatively overturn predictions based on simpler single-species models
IgE-mediated histamine release from nasal mucosa is inhibited by SLPI (secretory leukocyte protease inhibitor) to the level of spontaneous release.
The secretory leukocyte protease inhibitor (SLPI) is a low-molecular-weight inhibitor of proteases, such as elastase and cathepsin G which are released from leukocytes during phagocytosis. The purpose of this study was to determine whether or not SLPI is able to inhibit IgE-mediated histamine release. Nasal mucosa from 11 test subjects without atopic disposition was used for this in vitro study. We found that SLPI inhibited histamine release in a dose-dependent way but was without influence on the spontaneous release
Experimental f-value and isotopic structure for the Ni I line blended with [OI] at 6300A
We have measured the oscillator strength of the Ni I line at 6300.34 \AA,
which is known to be blended with the forbidden [O I] 6300 line, used
for determination of the oxygen abundance in cool stars. We give also
wavelengths of the two isotopic line components of Ni and Ni
derived from the asymmetric laboratory line profile. These two line components
of Ni I have to be considered when calculating a line profile of the 6300 \AA\
feature observed in stellar and solar spectra. We also discuss the labelling of
the energy levels involved in the Ni I line, as level mixing makes the
theoretical predictions uncertain.Comment: Accepted for publication in ApJLetter
The FERRUM project: radiative lifetimes of the 3d(5)(S-6)4s4p(P-3)y P-6 degrees states of FeII measured with time-resolved vacuum ultra-violet laser spectroscopy
We report on lifetime measurements of the 3d(5)(S-6)4s4p(P-3)y P-6 degrees states of Fe II using time-resolved vacuum ultraviolet (VUV) laser spectroscopy. A laser-produced plasma has been used as the source of free Fe+ ions. The tunable VUV radiation was obtained employing resonantly enhanced sum-difference four-wave-mixing of short laser pulses. We obtained tau((6)P(3/2)degrees) = 3.90(20) ns, tau((6)P(5/2)degrees) = 3.80(20) ns and tau((6)P(7/2)degrees) = 3.65(20) ns
Experimental Pd II oscillator strengths and the palladium abundance in the HgMn-type star chi Lupi
Experimental oscillator strengths for 19 ultraviolet lines of Pd II have been derived from measurements of line intensities in calibrated Fourier transform spectra, combined with picosecond-pulse laser measurements of radiative lifetimes. Five of these 19 lines, in addition to other Pd nr lines, are present in Hubble Space Telescope/Goddard High-Resolution Spectrograph echelle spectra of the chemically peculiar HgMn star chi Lupi, yielding a palladium abundance of log (N-Pd) = +5.0, which is 3.3 dex above the solar abundance. Theoretical oscillator strengths have been calculated for all strong ultraviolet transitions associated with the lowest odd-parity configuration of Pd II
Partial clinical remission in type 1 diabetes: a comparison of the accuracy of total daily dose of insulin of \u3c0.3 units/kg/day to the gold standard insulin-dose adjusted hemoglobin A1c of ≤9 for the detection of partial clinical remission
BACKGROUND: It is unclear whether the gold standard test for the detection of partial clinical remission (PCR) in new-onset type 1 diabetes (T1D), the insulin-dose adjusted Hemoglobin A1c (IDAA1c) of ≤9, is superior to a new tool, total daily dose of insulin (TDD) of
METHODS: A retrospective analysis of 204 subjects of ages 2-14 years, mean age 7.9±3.2 years, (male 7.8±3.4 years, [n=98]; female 7.9±3.0 years, [n=106], p=0.816) with new-onset T1D. Anthropometric and biochemical data were collected for the first 36 months of disease. PCR was defined by both IDAA1c≤9 and TDD
RESULTS: There were 86 (42.2%) (age 9.1±3.0 years; male 57%) remitters by IDAA1c≤9 criterion, and 82 (40.2%) remitters (age 7.3±2.8 years) by TDD of
CONCLUSIONS: There were no significant differences in the number of remitters, duration of PCR, or the time of peak remission defined by IDAA1c of ≤9 or TDD o
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