14,239 research outputs found
Wind enhanced planetary escape: Collisional modifications
The problem of thermal escape is considered in which both the effects of thermospheric winds at the exobase and collisions below the exobase are included in a Monte Carlo calculation. The collisions are included by means of a collisional relaxation layer of a background gas which models the transition region between the exosphere and the thermosphere. The wind effects are considered in the limiting cases of vertical and horizontal flows. Two species are considered: terrestrial hydrogen and terrestrial helium. In the cases of terrestrial hydrogen the escape fluxes were found to be strongly filtered or throttled by collisions at high exospheric temperatures. The model is applied to molecular hydrogen diffusing through a methane relaxation layer under conditions possible on Titan. The results are similar to the case of terrestrial hydrogen with wind enhanced escape being strongly suppressed by collisions. It is concluded that wind enhanced escape is not an important process on Titan
Charged di-boson production at the LHC in a 4-site model with a composite Higgs boson
We investigate the scope of the LHC in probing the parameter space of a
4-site model supplemented by one composite Higgs state, assuming all past,
current and future energy and luminosity stages of the CERN machine. We
concentrate on the yield of charged di-boson production giving two
opposite-charge different-flavour leptons and missing (transverse) energy,
i.e., events induced via the subprocess
+ , which enables the production in the intermediate step of all
additional neutral and charged gauge bosons belonging to the spectrum of this
model, some of which in resonant topologies. We find this channel accessible
over the background at all LHC configurations after a dedicated cut-based
analysis. We finally compare the yield of the di-boson mode to that of
Drell-Yan processes and establish that they have complementary strengths, one
covering regions of parameter space precluded to the others and vice versa.Comment: 36 pages, 13 figures, 13 table
Cranial sutures work collectively to distribute strain throughout the reptile skull
The skull is composed of many bones that come together at sutures. These sutures are important sites of growth, and as growth ceases some become fused while others remain patent. Their mechanical behaviour and how they interact with changing form and loadings to ensure balanced craniofacial development is still poorly understood. Early suture fusion often leads to disfiguring syndromes, thus is it imperative that we understand the function of sutures more clearly. By applying advanced engineering modelling techniques, we reveal for the first time that patent sutures generate a more widely distributed, high level of strain throughout the reptile skull. Without patent sutures, large regions of the skull are only subjected to infrequent low-level strains that could weaken the bone and result in abnormal development. Sutures are therefore not only sites of bone growth, but could also be essential for the modulation of strains necessary for normal growth and development in reptiles
A REGIONAL COMPARISON OF RISK-EFFICIENT SOYBEAN MARKETING STRATEGIES
Risk-efficient portfolios from a subset of marketing strategies were identified using Target-MOTAD. Portfolios were generated for Illinois, Arkansas, and South Carolina to determine whether regional price and yield characteristics affected the optimal marketing strategy selection during 1972-1985. The results support previous conclusions that the risk borne when following a combination of marketing strategies was less than the risk of any single marketing strategy examined. The results also show that the marketing strategies representing efficient risk-return combinations for a producer in one region were different from the efficient risk-return combinations for a producer in another region. Therefore, generic marketing advice would have produced results less preferred in one region than in another.Marketing,
Estrogen-treated rats alter salt intake after repeated episodes of dietary sodium deficiency
Background: Sex differences in sodium intake are apparent; however, estrogen's role in these differences is currently unclear. Previous studies examining repeated episodes of furosemide-induced sodium depletion showed that while stimulated salt intake was similar between males and females, there were clear sex differences in sodium intake after rats were sodium replete. We aimed to further elucidate the long-term effects of estrogen on sodium intake using repeated episodes of a low salt diet, a more physiological challenge.Methods: Ovariectomized rats were placed on two-week periods of access to regular chow (NaR) or sodium deficient chow (NaD), which we alternated for a total of two exposures to each diet. Estrogen benzoate (EB) or oil injections were given twice weekly throughout the experiment. At the end of each diet period, rats were given a 2-hour two-bottle test (water and 0.5 M NaCl). At the end of the experiment, rats were sacrificed and trunk blood was collected and centrifuged to collect plasma. Plasma protein levels were measured. Uteri were collected and 1 cm segments of the uterine horns were weighed.Results: We confirmed the efficacy of EB treatment via effects on body weight, uterine weight, and plasma proteins. Specifically, EB-treated rats maintained body weight throughout the experiment, with the expected transient decreases corresponding to the EB injection schedule, while oil-treated rats gained weight. In addition, both plasma proteins and uterine weights were greatly increased in EB-treated rats compared to oil-treated rats. During two-bottle tests, both EB- and oil-treated rats had similar baseline intakes of 0.5 M NaCl and water. When salt intake was stimulated by dietary sodium deficiency, both EB- and oil-treated rats drank similarly increased amounts of 0.5 M NaCl. Interestingly, EB- treated rats drank more 0.5 M NaCl and water than did oil-treated rats following return to regular chow. The second period of dietary sodium deficiency again elicited similar intakes of 0.5 M NaCl and water by EB- and oil-treated rats.Conclusions: Our study demonstrated that estrogen did not alter salt intake induced by the physiological challenge, dietary sodium deficiency. However, the low salt diet led to persistent changes in behavior, as demonstrated by the continued consumption of salt and water by EB-treated rats even after sodium repletion
AN INTRODUCTION TO SPATIAL MODELING IN FISHERIES ECONOMICS
Resource /Energy Economics and Policy,
Decay widths of large-spin mesons from the non-critical string/gauge duality
In this paper, we use the non-critical string/gauge duality to calculate the
decay widths of large-spin mesons. Since it is believed that the string theory
of QCD is not a ten dimensional theory, we expect that the non-critical
versions of ten dimensional black hole backgrounds lead to better results than
the critical ones. For this purpose we concentrate on the confining theories
and consider two different six dimensional black hole backgrounds. We choose
the near extremal AdS6 model and the near extremal KM model to compute the
decay widths of large-spin mesons. Then, we present our results from these two
non-critical backgrounds and compare them together with those from the critical
models and experimental data.Comment: 21 pages and 3 figure
Problem areas in the use of the firefly luciferase assay for bacterial detection
By purifying the firefly luciferase extract and adding all necessary chemicals but ATP in excess, an assay for ATP was performed by measuring the amount of light produced when a sample containing soluble ATP is added to the luciferase reaction mixture. Instrumentation, applications, and basic characteristics of the luciferase assay are presented. Effect of the growth medium and length of time grown in this medium on ATP per viable E. coli values is shown in graphic form, along with an ATP concentration curve showing relative light units versus ATP injected. Reagent functions and concentration methods are explored. Efforts to develop a fast automatable system to detect the presence of bacteria in biological fluids, especially urine, resulted in the optimization of procedures for use with different types of samples
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