21,479 research outputs found
Role of Landau-Rabi quantization of electron motion on the crust of magnetars within the nuclear energy density functional theory
Magnetic fields of order G have been measured at the surface of
some neutron stars, and much stronger magnetic fields are expected to be
present in the solid region beneath the surface. The effects of the magnetic
field on the equation of state and on the composition of the crust due to
Landau-Rabi quantization of electron motion are studied. Both the outer and
inner crustal regions are described in a unified and consistent way within the
nuclear-energy density functional theory.Comment: 23 pages, 11 figure
Inclusion of seasonal variation in river system microbial communities and phototroph activity increases environmental relevance of laboratory chemical persistence tests
Regulatory tests assess crop protection product environmental fate and toxicity before approval for commercial use. Although globally applied laboratory tests can assess biodegradation, they lack environmental complexity. Microbial communities are subject to temporal and spatial variation, but there is little consideration of these microbial dynamics in the laboratory. Here, we investigated seasonal variation in the microbial composition of water and sediment from a UK river across a two-year time course and determined its effect on the outcome of water-sediment (OECD 308) and water-only (OECD 309) biodegradation tests, using the fungicide isopyrazam. These OECD tests are performed under dark conditions, so test systems incubated under non-UV light:dark cycles were also included to determine the impact on both inoculum characteristics and biodegradation. Isopyrazam degradation was faster when incubated under non-UV light at all collection times in water-sediment microcosms, suggesting that phototrophic communities can metabolise isopyrazam throughout the year. Degradation rate varied seasonally between inoculum collection times only in microcosms incubated in the light, but isopyrazam mineralisation to 14CO2 varied seasonally under both light and dark conditions, suggesting that heterotrophic communities may also play a role in degradation. Bacterial and phototroph communities varied across time, but there was no clear link between water or sediment microbial composition and variation in degradation rate. During the test period, inoculum microbial community composition changed, particularly in non-UV light incubated microcosms. Overall, we show that regulatory test outcome is not influenced by temporal variation in microbial community structure; however, biodegradation rates from higher tier studies with improved environmental realism, e.g. through addition of non-UV light, may be more variable. These data suggest that standardised OECD tests can provide a conservative estimate of pesticide persistence end points and that additional tests including non-UV light could help bridge the gap between standard tests and field studies
De-blending Deep Herschel Surveys: A Multi-wavelength Approach
Cosmological surveys in the far infrared are known to suffer from confusion.
The Bayesian de-blending tool, XID+, currently provides one of the best ways to
de-confuse deep Herschel SPIRE images, using a flat flux density prior. This
work is to demonstrate that existing multi-wavelength data sets can be
exploited to improve XID+ by providing an informed prior, resulting in more
accurate and precise extracted flux densities. Photometric data for galaxies in
the COSMOS field were used to constrain spectral energy distributions (SEDs)
using the fitting tool CIGALE. These SEDs were used to create Gaussian prior
estimates in the SPIRE bands for XID+. The multi-wavelength photometry and the
extracted SPIRE flux densities were run through CIGALE again to allow us to
compare the performance of the two priors. Inferred ALMA flux densities
(F), at 870m and 1250m, from the best fitting SEDs from the
second CIGALE run were compared with measured ALMA flux densities (F) as an
independent performance validation. Similar validations were conducted with the
SED modelling and fitting tool MAGPHYS and modified black body functions to
test for model dependency. We demonstrate a clear improvement in agreement
between the flux densities extracted with XID+ and existing data at other
wavelengths when using the new informed Gaussian prior over the original
uninformed prior. The residuals between F and F were calculated. For
the Gaussian prior, these residuals, expressed as a multiple of the ALMA error
(), have a smaller standard deviation, 7.95 for the Gaussian
prior compared to 12.21 for the flat prior, reduced mean, 1.83
compared to 3.44, and have reduced skew to positive values, 7.97
compared to 11.50. These results were determined to not be significantly model
dependent. This results in statistically more reliable SPIRE flux densities.Comment: 8 pages, 7 figures, 3 tables. Accepted for publication in A&
Extracting quantum dynamics from genetic learning algorithms through principal control analysis
Genetic learning algorithms are widely used to control ultrafast optical
pulse shapes for photo-induced quantum control of atoms and molecules. An
unresolved issue is how to use the solutions found by these algorithms to learn
about the system's quantum dynamics. We propose a simple method based on
covariance analysis of the control space, which can reveal the degrees of
freedom in the effective control Hamiltonian. We have applied this technique to
stimulated Raman scattering in liquid methanol. A simple model of two-mode
stimulated Raman scattering is consistent with the results.Comment: 4 pages, 5 figures. Presented at coherent control Ringberg conference
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Prepubertal Ontogeny of Luteinizing Hormone-Releasing Hormone Immunoreactivity in Developing Pig Brain
Luteinizing hormone-releasing hormone (LHRH, GnRH) is a 10-amino acid peptide produced in the brain that regulates the release of LH from the pituitary gland. LH is crucial for initiating the successful ovulation of mature ovarian follicles (Graafian follicles) and transforming the ovulated follicle into a steroid-secreting corpus luteum. In the male, LH causes Leydig cells in the testis to secrete testosterone, a hormone essential for male sexual behavior secretory activity of accessory glands of the reproductive tract, muscle accretion, and spermatogenesis. The focus of this study was to determine the prepubertal ontogeny of LHRH-like immunoreactivity (LHRH-IR) in the male Chinese Meishan pig. The Meishan breed is known for reproductive traits, including increased litter size and precocious puberty, but slow growth and obesity. Brains of animals from gestational day (g) 30, 50, 70, 90, and 110 and postnatal day (pn) 1, 10, 20, and 50 (duration of pregnancy averages 114 days) were processed by a standard immunohistochemical technique utilizing a commercially available rabbit anti-LHRH antibody. Coronal sections of the brain revealed LHRH-IR in cell bodies and fibers at g30 entering the brain via the terminal nerve and in the septal region of the basal telencephalon. The numbers of LHRH-IR cells increased at g50 and cells were localized to the septum, organum vasculosum of the lamina terminalis, optic area, and lateral hypothalamus whereas immunoreactive fibers were present throughout the septum and hypothalamus and had reached the median eminence, the lowest connecting link to the anterior pituitary gland. Results from this study indicate that LHRH may be present in the Meishan brain earlier during development and fibers containing LHRH-IR appear in the median eminence (lower part of the hypothalamus near the pituitary gland) earlier than previously reported for the domestic pig. These results suggest a breed difference in the ontogeny of reproductive control systems in the pig. An understanding of the LHRH neuronal network within the brain and hormones and exteroceptive factors that affect its secretion of LHRH that, in turn, causes gonadotropin (luteinizing hormone and follicle stimulating hormone) secretion by the pituitary gland will reveal neuroendocrine mechanisms regulating reproduction in the pig
Supersonic Flow of Chemically Reacting Gas-Particle Mixtures. Volume 2: RAMP - A Computer Code for Analysis of Chemically Reacting Gas-Particle Flows
A computer program written in conjunction with the numerical solution of the flow of chemically reacting gas-particle mixtures was documented. The solution to the set of governing equations was obtained by utilizing the method of characteristics. The equations cast in characteristic form were shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The characteristic directions for the gas-particle system are found to be the conventional gas Mach lines, the gas streamlines and the particle streamlines. The basic mesh construction for the flow solution is along streamlines and normals to the streamlines for axisymmetric or two-dimensional flow. The analysis gives detailed information of the supersonic flow and provides for a continuous solution of the nozzle and exhaust plume flow fields. Boundary conditions for the flow solution are either the nozzle wall or the exhaust plume boundary
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