177 research outputs found
Phosphorus, Crude Protein, and Digestible Dry Matter Concentrations of Forage Selected by Grazing Beef Cattle
Phosphorus (P) is an essential nutrient for beef cattle, but over-supplementation of P may have negative environmental and economic impacts. The P concentration in forage selected by grazing cattle may be sufficient to meet the nutritional requirements without supplementation. Similarly, the crude protein (CP) and in vitro digestible dry matter (IVDDM) concentration of forage selected by grazing cattle may be greater than available forage. This study was conducted to determine the P, CP, and IVDDM concentrations of forage selected by beef cattle grazing cool-season grass pastures. Fifteen fall-calving Angus cows were managed by either continuous or rotational stocking in 30-acre smooth bromegrass pastures, replicated twice. In July and August, one ruminally fistulated steer was placed in each pasture for one week. On two consecutive days at the end of each week, fistulated steers were ruminally evacuated, allowed to graze for 2 h, and sampled for forage selected during grazing. Forage samples were hand-clipped at ground level and from the upper half of the forage sward in pasture areas adjacent to the areas being grazed. A subsample of the ground-clipped forage was placed in the rumen and allowed to soak for 2 h following sampling of selected forage to correct the P, CP, and IVDDM concentrations in the selected forage for salivary P, CP, and IVDDM absorbed by selected forage. Hand-clipped and selected forage samples were analyzed for P, CP and IVDDM concentrations. Phosphorus concentrations in the available forage did not differ by month. However, P concentrations of available forage in continuously stocked pastures (0.22%) tended to be greater than in rotationally stocked pastures (0.20%). The P concentration of selected forage (0.39%) was almost twice as high as the available forage. Available forage in pastures managed by continuous stocking had greater CP and IVDDM concentrations than did forage in rotationally stocked pastures in both months. Results of this study show that cattle grazing cool-season grass pastures are able to select forage with an adequate crude protein and P concentrations to meet their nutrient requirement without supplementatio
Зв'язок сейсмічної активності з атмосферним інфразвуком
The connection the infrasonic fluctuations in an atmosphere with seismic activity in some region for period 1997–2000 are considered in the work. The model of stationary random process is used for the analysis. The coordination spectral of the characteristics infrasound and seismic activity are shown for the given period of time. The analysis of researches shows change of a spectrum infrasound before earthquake
Longitudinal Polarization at future Colliders and Virtual New Physics Effects
The theoretical merits of longitudinal polarization asymmetries of
electron-positron annihilation into two final fermions at future colliders are
examined, using a recently proposed theoretical description. A number of
interesting features, valid for searches of virtual effects of new physics, is
underlined, that is reminiscent of analogous properties valid on top of
resonance. As an application to a concrete example, we consider the case of a
model with triple anomalous gauge couplings and show that the additional
information provided by these asymmetries would lead to a drastic reduction of
the allowed domain of the relevant parameters.Comment: 18 pages and 1 figure. e-mail: [email protected]
Ion and proton loss paterns at the SPS and LHC
The collimation system of the LHC, primarily designed for proton operation, must function safely also with 208Pb82+ions. However, the particle-matter interaction in a collimator is different for heavy ions and protons. Heavy ions are subject to nuclear fragmentation, which creates a spectrum of secondary particles exiting the collimators with a Z/A ratio different from the nominal beam. These particles could be lost in a superconducting magnet and the induced heating might cause a quench. The program ICOSIM has previously been used to simulate these losses in the LHC. In this article, we present a benchmark of ICOSIM, using measured proton and ion loss maps in the SPS, and find a good qualitative agreement. We also make a quantitative comparison where the showers of the lost particles are simulated with the FLUKA code in the full magnet geometry. Here a discrepancy of a factor 3.8 is found. Estimation of expected uncertainties continues
RAS gene polymorphisms, classical risk factors and the advent of coronary artery disease in the Portuguese population
<p>Abstract</p> <p>Background</p> <p>Several polymorphisms within the renin-angiotensin system cluster of genes have been associated with the advent of coronary artery disease (CAD) or related pathologies. We investigated the distribution of 5 of these polymorphisms in order to find any association with CAD development and distinguish if any of the biochemical and behavioural factors interact with genetic polymorphisms in the advent of the disease.</p> <p>Methods</p> <p><it>ACE </it>I/D (rs4340), <it>ACE </it>A11860G (rs4343), <it>AT1R </it>A1166C (rs5186), <it>AGT </it>T174M (rs4762) and <it>AGT </it>M235T (rs699) gene polymorphisms were PCR-RFLP analysed in 298 CAD patients and 510 controls from Portugal. Several biochemical and behavioural markers were obtained.</p> <p>Results</p> <p><it>ACE </it>I/D DD and <it>ACE</it>11860 GG genotypes are risk factors for CAD in this population. The simultaneous presence of <it>ACE </it>I/D I and <it>ACE</it>11860 A alleles corresponds to a significant trend towards a decrease in CAD incidence. We found several synergistic effects between the studied polymorphisms and classical risk factors such as hypertension, obesity, diabetes and dyslipidaemia: the presence of the DD genotype of <it>ACE </it>I/D (and also <it>ACE</it>11860 GG) increases the odds of developing CAD when associated to each one of these classical risk factors, particularly when considering the male and early onset CAD subgroup analysis; <it>AGT</it>235 TT also increases the CAD risk in the presence of hypertension and dyslipidaemia, and <it>AT1R</it>1166 interacts positively with hypertension, smoking and obesity.</p> <p>Conclusion</p> <p><it>ACE </it>polymorphisms were shown to play a major role in individual susceptibility to develop CAD. There is also a clear interaction between RAS predisposing genes and some biochemical/environmental risk factors in CAD onset, demonstrating a significant enhancement of classical markers particularly by <it>ACE </it>I/D and <it>ACE</it>11860.</p
Acute-Phase-HDL Remodeling by Heparan Sulfate Generates a Novel Lipoprotein with Exceptional Cholesterol Efflux Activity from Macrophages
During episodes of acute-inflammation high-density lipoproteins (HDL), the carrier of so-called good cholesterol, experiences a major change in apolipoprotein composition and becomes acute-phase HDL (AP-HDL). This altered, but physiologically important, HDL has an increased binding affinity for macrophages that is dependent on cell surface heparan sulfate (HS). While exploring the properties of AP-HDL∶HS interactions we discovered that HS caused significant remodeling of AP-HDL. The physical nature of this change in structure and its potential importance for cholesterol efflux from cholesterol-loaded macrophages was therefore investigated. In the presence of heparin, or HS, AP-HDL solutions at pH 5.2 became turbid within minutes. Analysis by centrifugation and gel electrophoresis indicated that AP-HDL was remodeled generating novel lipid poor particles composed only of apolipoprotein AI, which we designate β2. This remodeling is dependent on pH, glycosaminoglycan type, is promoted by Ca2+ and is independent of protease or lipase activity. Compared to HDL and AP-HDL, remodeled AP-HDL (S-HDL-SAA), containing β2 particles, demonstrated a 3-fold greater cholesterol efflux activity from cholesterol-loaded macrophage. Because the identified conditions causing this change in AP-HDL structure and function can exist physiologically at the surface of the macrophage, or in its endosomes, we postulate that AP-HDL contains latent functionalities that become apparent and active when it associates with macrophage cell surface/endosomal HS. In this way initial steps in the reverse cholesterol transport pathway are focused at sites of injury to mobilize cholesterol from macrophages that are actively participating in the phagocytosis of damaged membranes rich in cholesterol. The mechanism may also be of relevance to aspects of atherogenesis
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The extratropical upper troposphere and lower stratosphere
The extratropical upper troposphere and lower stratosphere (Ex-UTLS) is a transition region between the stratosphere and the troposphere. The Ex-UTLS includes the tropopause, a strong static stability gradient and dynamic barrier to transport. The barrier is reflected in tracer profiles. This region exhibits complex dynamical, radiative, and chemical characteristics that place stringent spatial and temporal requirements on observing and modeling systems. The Ex-UTLS couples the stratosphere to the troposphere through chemical constituent transport (of, e.g., ozone), by dynamically linking the stratospheric circulation with tropospheric wave patterns, and via radiative processes tied to optically thick clouds and clear-sky gradients of radiatively active gases. A comprehensive picture of the Ex-UTLS is presented that brings together different definitions of the tropopause, focusing on observed dynamical and chemical structure and their coupling. This integral view recognizes that thermal gradients and dynamic barriers are necessarily linked, that these barriers inhibit mixing and give rise to specific trace gas distributions, and that there are radiative feedbacks that help maintain this structure. The impacts of 21st century anthropogenic changes to the atmosphere due to ozone recovery and climate change will be felt in the Ex-UTLS, and recent simulations of these effects are summarized and placed in context
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