59,936 research outputs found
Observations on the Nesting of \u3ci\u3eCrabro Tenuis\u3c/i\u3e (Hymenoptera: Sphecidae)
Three nests of Crabro tenuis were studied during June 1971-1972 in Oswego County, New York. Females constructed shallow but lengthy, multicelled nests in sand with the cells being built in clusters, sometimes in series. Females plugged the entrances with damp sand and occupied the burrows during midday. Paralyzed prey were stored head inward at the end of the burrow. The deeper cells in a cluster were excavated and provisioned first and the shallower cells built and stored later, as determined by the developmental stages of the wasps within the cells. From four to seven paralyzed, adult male flies were placed in a fully provisioned cell with their venters toward the center. Such a cell usually held only one species of fly. Provisions consisted of the suborders Brachycera and Cyclorrhapha and comprised the families Rhagionidae, Anthomyiidae and Tachinidae. An egg was affixed about equally to the left or right side of the neck of a fly and this prey was placed against or near the wall of the cell. The nesting traits of C. tenuis were compared with those of other members of the Cribrarius group, C. advena of the Advena, group, C. venator of the Tumidus group and species in the Hilaris group
Range Extensions for Species of Sphecidae (Hymenoptera) in the Northeastern United States
The ranges of 10 Nearctic species of Sphecidae, Spilomena pusilla, Tachytes parvus, Solierella plenoculoides, Pison agile, Entomognathus lenapeorum, Rhopalum clavipes, Crabro hilaris, C. tenuis, Alysson conicus and Lestiphorus cockerelli, are extended in the northeastern U.S. based upon collections made in Pennsylvania and New York. The first prey record for a North American species of Lestiphorus, cockerelli, is included
Development of Beluga, Delphinapterus leucas, Capture and Satellite Tagging Protocol in Cook Inlet, Alaska
Attempts to capture and place satellite tags on belugas, Delphinapterus leucas, in Cook Inlet, Alaska were conducted during late spring and summer of 1995, 1997, and 1999. In 1995, capture attempts using a hoop net proved impractical in Cook Inlet. In 1997, capture efforts focused on driving belugas into nets. Although this method had been successful in the Canadian High Arctic, it failed in Cook Inlet due to the ability of the whales to detect and avoid nets in shallow and very turbid water. In 1999, belugas were successfully captured using a gillnet encirclement technique. A satellite tag was attached to a juvenile male, which subsequently provided the first documentation of this species’ movements within Cook Inlet during the summer months (31 May–17 September)
Comparison of hydrogen and methane as coolants in regeneratively cooled panels
Comparison of hydrogen and methane as coolants in regeneratively cooled panel
Black Hole Mass of the Ultraluminous X-ray source M82 X-1
We report the first clear evidence for the simultaneous presence of a low
frequency break and a QPO in the fluctuation power spectrum of a well known
ultraluminous X-ray source (ULX) in M82 using long XMM-Newton observations. The
break occurs at a frequency of 34.2_{-3}^{+6}mHz. The QPO has a centroid at
114.3\pm1.5mHz, a coherence Q~3.5 and an amplitude (rms) of 19% in the 2-10keV
band. The power spectrum is approximately flat below the break frequency and
then falls off above the break frequency as a power law with the QPO
superimposed. This form of the power spectrum is characteristic of the Galactic
X-ray binaries (XRBs) in their high or intermediate states. M82 X-1 was likely
in an intermediate state during the observation. The EPIC PN spectrum is well
described by a model comprising an absorbed power-law (Gamma~2) and an iron
line at ~6.6keV with a width sigma~0.2keV and an equivalent width of ~180eV.
Using the well established correlations between the power and energy spectral
parameters for XRBs, we estimate a black hole mass for M82 X-1 in the range of
25-520Msun including systematic errors that arise due to the uncertainty in the
calibration of the photon spectral index versus QPO frequency relation.Comment: Final version, accepted for publication in ApJ Letter
A microscopic study of solid/liquid phase change in several members of the paraffin family
Microscopic study of solid/liquid phase change in several members of paraffin famil
A Genetic Locus Regulates the Expression of Tissue-Specific mRNAs from Multiple Transcription Units
129 GIX- mice, unlike animals of the congeneic partner strain GIX+, do not express significant amounts of the retroviral antigens gp70 and p30. Evidence is presented indicating that the GIX phenotype is specified by a distinct regulatory gene acting on multiple transcription units to control the levels of accumulation of specific mRNA species. The steady-state levels of retroviral-homologous mRNA from the tissues of GIX+ and GIX- mice were examined by blot hybridization using as probes DNA fragments from cloned murine leukemia viruses. RNA potentially encoding viral antigens was reduced or absent in GIX- mice, even though no differences in integrated viral genomes were detected between these congeneic strains by DNA blotting. Tissue-specific patterns of accumulation of these RNA species were detected in brain, epididymis, liver, spleen, and thymus, and several distinct RNA species were found to be coordinately regulated with the GIX phenotype. Measurements of RNA synthesis suggest a major role for transcriptional control in the regulation of some retroviral messages
Using nonequilibrium fluctuation theorems to understand and correct errors in equilibrium and nonequilibrium discrete Langevin dynamics simulations
Common algorithms for computationally simulating Langevin dynamics must
discretize the stochastic differential equations of motion. These resulting
finite time step integrators necessarily have several practical issues in
common: Microscopic reversibility is violated, the sampled stationary
distribution differs from the desired equilibrium distribution, and the work
accumulated in nonequilibrium simulations is not directly usable in estimators
based on nonequilibrium work theorems. Here, we show that even with a
time-independent Hamiltonian, finite time step Langevin integrators can be
thought of as a driven, nonequilibrium physical process. Once an appropriate
work-like quantity is defined -- here called the shadow work -- recently
developed nonequilibrium fluctuation theorems can be used to measure or correct
for the errors introduced by the use of finite time steps. In particular, we
demonstrate that amending estimators based on nonequilibrium work theorems to
include this shadow work removes the time step dependent error from estimates
of free energies. We also quantify, for the first time, the magnitude of
deviations between the sampled stationary distribution and the desired
equilibrium distribution for equilibrium Langevin simulations of solvated
systems of varying size. While these deviations can be large, they can be
eliminated altogether by Metropolization or greatly diminished by small
reductions in the time step. Through this connection with driven processes,
further developments in nonequilibrium fluctuation theorems can provide
additional analytical tools for dealing with errors in finite time step
integrators.Comment: 11 pages, 4 figure
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