20,432 research outputs found
Dietary variations in three co-occurring rockfish species off the Pacific Northwest during anomalous oceanographic events in 1998 and 1999
Stomach samples from three rockfish species, yellowtail
(Sebastes f lavidus), widow (S. entomelas), and canary (S. pinniger) rockfish, seasonally collected off the Pacific Northwest in 1998 and 1999, provided quantitative information on the food habits of these species during and after the 1997–98 El Niño event. Although euphausiids were the most common major prey of all three predators, gelatinous zooplankton and fishes were the most commonly
consumed prey items during some seasonal quarters. The influence of the El Niño event was evident in the diets. Anomalous prey items, including the southern euphausiid species Nyctiphanes simplex and juveniles of Pacific whiting (Merluccius productus) frequently appeared in the diets in the spring and summer of 1998. The results of stomach contents analyses, based on 905 stomach samples from 49 trawl hauls during seven commercial fishing trips and from 56 stations during research surveys, were consistent with the timing of occurrence and the magnitude of change in biomass of some zooplankton species reported
from zooplankton studies in the northern California Current during the 1997–98 El Niño. Our findings indicate that the observed variations of prey groups in some rockfish diets
may be a function of prey variability related to climate and environment changes
Statistical Self-Similar Properties of Complex Networks
It has been shown that many complex networks shared distinctive features,
which differ in many ways from the random and the regular networks. Although
these features capture important characteristics of complex networks, their
applicability depends on the type of networks. To unravel ubiquitous
characteristics that complex networks may have in common, we adopt the
clustering coefficient as the probability measure, and present a systematic
analysis of various types of complex networks from the perspective of
statistical self-similarity. We find that the probability distribution of the
clustering coefficient is best characterized by the multifractal; moreover, the
support of the measure had a fractal dimension. These two features enable us to
describe complex networks in a unified way; at the same time, offer unforeseen
possibilities to comprehend complex networks.Comment: 11 pages, 4 figure
Ground states and thermal states of the random field Ising model
The random field Ising model is studied numerically at both zero and positive
temperature. Ground states are mapped out in a region of random and external
field strength. Thermal states and thermodynamic properties are obtained for
all temperatures using the the Wang-Landau algorithm. The specific heat and
susceptibility typically display sharp peaks in the critical region for large
systems and strong disorder. These sharp peaks result from large domains
flipping. For a given realization of disorder, ground states and thermal states
near the critical line are found to be strongly correlated--a concrete
manifestation of the zero temperature fixed point scenario.Comment: 5 pages, 5 figures; new material added in this versio
Feminist Perspective of Cross-gender Power Relation in Caryl Churchill's Top Girls
Top Girls, one of Caryl Churchill's most popular plays, describes the lives of six female characters coming from different centuries. Each of them has their own story to tell, as they have all been victimized by the patriarchal system in the century when they live and have resisted the system with different strategies. They either employ roles that are traditionally reserved for men or they adopt the archetypically feminine qualities. Despite their resistance and success, they find themselves unhappy and unsatisfied over their achievements. Thus this raises the question of the effectiveness of the feminist movement
An extension of SaalschĂĽtz's summation theorem for the series <sub><i>r</i>+3</sub>F<sub><i>r</i>+2</sub>
The aim in this research note is to provide an extension of SaalschĂĽtz's summation theorem for the series r+3Fr+2(1) when r pairs of numeratorial and denominatorial parameters differ by positive integers. The result is obtained by exploiting a generalization of an Euler-type transformation recently derived by Miller and Paris [Transformation formulas for the generalized hypergeometric function with integral parameter differences. Rocky Mountain J Math. 2013;43, to appear]
On a new class of summation formulae involving the Laguerre polynomial
By elementary manipulation of series, a general transformation involving the generalized hypergeometric function is established. Kummer’s first theorem, the classical Gauss summation theorem and the generalized Kummer summation theorem due to Lavoie et al. [Generalizations of Whipple’s theorem on the sum of a 3 F 2, J. Comput. Appl. Math. 72 (1996), pp. 293–300] are then applied to obtain a new class of summation formulae involving the Laguerre polynomial, which have not previously appeared in the literature. Several related results due to Exton have also been given in a corrected form
On two Thomae-type transformations for hypergeometric series with integral parameter differences
We obtain two new Thomae-type transformations for hypergeometric series with r pairs of numeratorial and denominatorial parameters differing by positive integers. This is achieved by application of the so-called Beta integral method developed by Krattenthaler and Rao [Symposium on Symmetries in Science (ed. B. Gruber), Kluwer (2004)] to two recently obtained Euler-type transformations. Some special cases are given
An opioid-like system regulating feeding behavior in C. elegans
Neuropeptides are essential for the regulation of appetite. Here we show that neuropeptides could regulate feeding in mutants that lack neurotransmission from the motor neurons that stimulate feeding muscles. We identified nlp-24 by an RNAi screen of 115 neuropeptide genes, testing whether they affected growth. NLP-24 peptides have a conserved YGGXX sequence, similar to mammalian opioid neuropeptides. In addition, morphine and naloxone respectively stimulated and inhibited feeding in starved worms, but not in worms lacking NPR-17, which encodes a protein with sequence similarity to opioid receptors. Opioid agonists activated heterologously expressed NPR-17, as did at least one NLP-24 peptide. Worms lacking the ASI neurons, which express npr-17, did not response to naloxone. Thus, we suggest that Caenorhabditis elegans has an endogenous opioid system that acts through NPR-17, and that opioids regulate feeding via ASI neurons. Together, these results suggestC. elegans may be the first genetically tractable invertebrate opioid model
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