336 research outputs found
Notes
Concealment Behavior of the Spanish Lobster, Scyllarides nodifer (Stimpson), with Observations on its Diel Activity. By L. A. Ogren
Notes of the Occurrence of the Silver Anchovy, Engraulis eurystole, in the Northern Gulf of Mexico. By R. W. Hastings
Studies on Decapod Crustacea from the Indian River Region of Florida VII. A Field Character for Rapid Identification of the Swimming Crabs Callinectes ornatus Ordway, 1863 and C. similis Williams, 1966 (Brachyura, Portunidae). By R.H. Gor
Food Habits of Juvenile American Alligators in the Upper Lake Pontchartrain Estuary
Food habits of juvenile (0.49-1.21 m total length) American alligators (Alligator mississippiensis) from an area in southeastern Louisiana were investigated. One-hundred and one stomach samples were obtained by stomach-pumping. Crustaceans (crayfish; blue crabs, Callinectes sapidus; grass shrimp, Palaemonetes sp.), insects (hemipterans, coleopterans), and small fish (least killifish, Heterandria formosa; mosquitofish, Gambusia affinis) constituted the majority of prey items taken. Fish consumption was significantly more frequent during April and May than during June through September (P\u3c0.025). This differential use of prey species may be due to seasonally fluctuating water levels in the study area. Comparisons of juvenile alligator food habits revealed dietary differences between Louisiana and Florida (P\u3c0.001), possibly due to the different prey available at the two areas. Prey utilization was not significantly different between larger alligators (0.9-1.2 m total length) and smaller alligators (0.3·0.9 m total length) (P\u3e0.25)
The Fish Fauna of Lake Maurepas, an Oligohaline Part of the Lake Pontchartrain Estuary
Lake Maurepas is a slightly saline body of water located at the upper end of the Lake Pontchartrain estuary. Of 67 fish species collected during 1983-84, 33 species (49%) are primarily freshwater, 6 (9%) are primarily marine, and 28 (42%) are estuarine or diadromous, commonly occurring in both freshwater and marine habitats. Major freshwater species (e.g. lctalurus furcatus, I. punctatus, and Aplodinotus grunniens) were present throughout the year, whereas most marine and estuarine species were seasonally present (e.g. Anchoa mitchilli, Brevoortia patronus, and Micropogonias undulatus), or were present during periods of higher (up to 2.5 o/oo) salinity (e.g. Cynoscion arenarius, Leiostomus xanthurus, and Pogonias cromis). Literature records indicate that larger percentages of marine species are present during years when salinities are higher (up to 8 o/oo)
Quantification of Reef Fish Assemblages: A Comparison of Several In Situ Methods
On two coral reef biotopes off St. Croix in the U.S. Virgin Islands a total of 41 in situ visual assessments of reef fish assemblages were conducted using six different methods. These methods included: transect, quadrat, random count, clnetransect, cineturret, and still photography. The dependent variables (numbers of species and species diversity) were examined for possible influence by the independent sample variables (time of day, amount of observation, time, reef site, and census method). Cluster analyses indicated that all methods gather data which allow community separation based on the sample variables. However, methods which tend to produce more information in terms of more species and numbers of individuals tend to recognize these sample variables more distinctly. Census assessment methods strongly Influenced the dependent variables. It is suspected that the amount of time employed for each method may be the most Important feature influencing in situ reef fish assemblage assessments
Simulation of truncated normal variables
We provide in this paper simulation algorithms for one-sided and two-sided
truncated normal distributions. These algorithms are then used to simulate
multivariate normal variables with restricted parameter space for any
covariance structure.Comment: This 1992 paper appeared in 1995 in Statistics and Computing and the
gist of it is contained in Monte Carlo Statistical Methods (2004), but I
receive weekly requests for reprints so here it is
The statistical mechanics of complex signaling networks : nerve growth factor signaling
It is becoming increasingly appreciated that the signal transduction systems
used by eukaryotic cells to achieve a variety of essential responses represent
highly complex networks rather than simple linear pathways. While significant
effort is being made to experimentally measure the rate constants for
individual steps in these signaling networks, many of the parameters required
to describe the behavior of these systems remain unknown, or at best,
estimates. With these goals and caveats in mind, we use methods of statistical
mechanics to extract useful predictions for complex cellular signaling
networks. To establish the usefulness of our approach, we have applied our
methods towards modeling the nerve growth factor (NGF)-induced differentiation
of neuronal cells. Using our approach, we are able to extract predictions that
are highly specific and accurate, thereby enabling us to predict the influence
of specific signaling modules in determining the integrated cellular response
to the two growth factors. We show that extracting biologically relevant
predictions from complex signaling models appears to be possible even in the
absence of measurements of all the individual rate constants. Our methods also
raise some interesting insights into the design and possible evolution of
cellular systems, highlighting an inherent property of these systems wherein
particular ''soft'' combinations of parameters can be varied over wide ranges
without impacting the final output and demonstrating that a few ''stiff''
parameter combinations center around the paramount regulatory steps of the
network. We refer to this property -- which is distinct from robustness -- as
''sloppiness.''Comment: 24 pages, 10 EPS figures, 1 GIF (makes 5 multi-panel figs + caption
for GIF), IOP style; supp. info/figs. included as brown_supp.pd
Coupled coarse graining and Markov Chain Monte Carlo for lattice systems
We propose an efficient Markov Chain Monte Carlo method for sampling
equilibrium distributions for stochastic lattice models, capable of handling
correctly long and short-range particle interactions. The proposed method is a
Metropolis-type algorithm with the proposal probability transition matrix based
on the coarse-grained approximating measures introduced in a series of works of
M. Katsoulakis, A. Majda, D. Vlachos and P. Plechac, L. Rey-Bellet and
D.Tsagkarogiannis,. We prove that the proposed algorithm reduces the
computational cost due to energy differences and has comparable mixing
properties with the classical microscopic Metropolis algorithm, controlled by
the level of coarsening and reconstruction procedure. The properties and
effectiveness of the algorithm are demonstrated with an exactly solvable
example of a one dimensional Ising-type model, comparing efficiency of the
single spin-flip Metropolis dynamics and the proposed coupled Metropolis
algorithm.Comment: 20 pages, 4 figure
Changes in health behavior and opinions among open-country families in two Missouri counties 1955-56 and 1968
Also available online.Digitized 2007 AES MoU
Quantum harmonic oscillator systems with disorder
We study many-body properties of quantum harmonic oscillator lattices with
disorder. A sufficient condition for dynamical localization, expressed as a
zero-velocity Lieb-Robinson bound, is formulated in terms of the decay of the
eigenfunction correlators for an effective one-particle Hamiltonian. We show
how state-of-the-art techniques for proving Anderson localization can be used
to prove that these properties hold in a number of standard models. We also
derive bounds on the static and dynamic correlation functions at both zero and
positive temperature in terms of one-particle eigenfunction correlators. In
particular, we show that static correlations decay exponentially fast if the
corresponding effective one-particle Hamiltonian exhibits localization at low
energies, regardless of whether there is a gap in the spectrum above the ground
state or not. Our results apply to finite as well as to infinite oscillator
systems. The eigenfunction correlators that appear are more general than those
previously studied in the literature. In particular, we must allow for
functions of the Hamiltonian that have a singularity at the bottom of the
spectrum. We prove exponential bounds for such correlators for some of the
standard models
High resolution spatial modelling of greenhouse gas emissions from land use change to energy crops in the UK
We implemented a spatial application of a previously evaluated model of soil GHG emissions, ECOSSE, in the United Kingdom to examine the impacts to 2050 of land-use transitions from existing land use, rotational cropland, permanent grassland or woodland, to six bioenergy crops; three ‘first-generation’ energy crops: oilseed rape, wheat and sugar beet, and three ‘second-generation’ energy crops: Miscanthus, short rotation coppice willow (SRC) and short rotation forestry poplar (SRF). Conversion of rotational crops to Miscanthus, SRC and SRF and conversion of permanent grass to SRF show beneficial changes in soil GHG balance over a significant area. Conversion of permanent grass to Miscanthus, permanent grass to SRF and forest to SRF shows detrimental changes in soil GHG balance over a significant area. Conversion of permanent grass to wheat, oilseed rape, sugar beet and SRC and all conversions from forest show large detrimental changes in soil GHG balance over most of the United Kingdom, largely due to moving from uncultivated soil to regular cultivation. Differences in net GHG emissions between climate scenarios to 2050 were not significant. Overall, SRF offers the greatest beneficial impact on soil GHG balance. These results provide one criterion for selection of bioenergy crops and do not consider GHG emission increases/decreases resulting from displaced food production, bio-physical factors (e.g. the energy density of the crop) and socio-economic factors (e.g. expenditure on harvesting equipment). Given that the soil GHG balance is dominated by change in soil organic carbon (SOC) with the difference among Miscanthus, SRC and SRF largely determined by yield, a target for management of perennial energy crops is to achieve the best possible yield using the most appropriate energy crop and cultivar for the local situation
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