46 resultados para Nature - Effect of human beings on


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Twelve variables were identified to define morphology in 109 calves sired by eight Pirenaica bulls widely used in artificial insemination. The effect of selection for weight at 210 days of age (W210) was detected from the regression coefficient between the 12 variables and the selection index for W210 used in the breeding plan. Unbiased estimates of the genetic correlated responses on the morphology were obtained without previously estimating the genetic correlation among traits. In Pirenaica cattle, selection for W210 increased slaughter live weight, chest depth and corporal length. The expected changes on height (withers, back and rump), rump width and thoracic perimeter were lower but positive and statistically significant.

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En este trabajo se analiza el efecto de la selección de datos sobre las estimaciones de heredabilidad. Se estimó el valor de heredabilidad del tamaño de camada en una población porcina en la que los datos correspondientes a las cerdas más viejas eran una muestra seleccionada. Las estimaciones se obtuvieron usando distintos conjuntos de datos derivados de toda la información disponible. Esos conjunto de datos se compararon evaluando su capacidad predictiva. Se vio que las estimaciones de heredabilidad obtenidas utilizando todos los datos disponibles correspondían a valores infraestimados. También se simuló un carácter materno y se generó un conjunto de datos seleccionados eliminando aquellos correspondientes a las hembras sin padres conocidos. Distintos modelos, habitualmente empleados cuando no existe selección de registros, se consideraron para estimar el valor de heredabilidad. Los resultados mostraron que ninguno de esos modelos ofrecía estimaciones insesgadas. Sólo los modelos que tenían en cuenta el efecto de la selección sobre la media residual y la media y varianza genéticas ofrecían estimaciones poco sesgadas. Sin embargo, para poder aplicarlos se debe conocer la selección realizada. El problema de la selección de datos es difícil de abordar cuando se desconoce cual es el proceso de selección que se ha realizado en una población.

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The effect of the heat flux on the rate of chemical reaction in dilute gases is shown to be important for reactions characterized by high activation energies and in the presence of very large temperature gradients. This effect, obtained from the second-order terms in the distribution function (similar to those obtained in the Burnett approximation to the solution of the Boltzmann equation), is derived on the basis of information theory. It is shown that the analytical results describing the effect are simpler if the kinetic definition for the nonequilibrium temperature is introduced than if the thermodynamic definition is introduced. The numerical results are nearly the same for both definitions

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Membrane-permeable calmodulin inhibitors, such as the napthalenesulfonamide derivatives W-7/W-13, trifluoperazine, and calmidazolium, are used widely to investigate the role of calcium/calmodulin (Ca2+/CaM) in living cells. If two chemically different inhibitors (e.g. W-7 and trifluoperazine) produce similar effects, investigators often assume the effects are due to CaM inhibition. Zeta potential measurements, however, show that these amphipathic weak bases bind to phospholipid vesicles at the same concentrations as they inhibit Ca 2 /CaM; this suggests that they also bind to the inner leaflet of the plasma membrane, reducing its negative electrostatic surface potential. This change will cause electrostatically bound clusters of basic residues on peripheral (e.g. Src and K-Ras4B) and integral (e.g. epidermal growth factor receptor (EGFR)) proteins to translocate from the membrane to the cytoplasm. We measured inhibitor-mediated translocation of a simple basic peptide corresponding to the calmodulin-binding juxtamembrane region of the EGFR on model membranes; W-7/W-13 causes translocation of this peptide from membrane to solution, suggesting that caution must be exercised when interpreting the results obtained with these inhibitors in living cells. We present evidence that they exert dual effects on autophosphorylation of EGFR;W-13 inhibits epidermal growth factordependent EGFR autophosphorylation under different experimental conditions, but in the absence of epidermal growth factor, W-13 stimulates autophosphorylation of the receptor in four different cell types. Our interpretation is that the former effect is due toW-13inhibition of Ca 2 /CaM, but thelatter results could be due to binding of W-13 to the plasma membrane.

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Objectives: The objective of this study was to evaluate the oral health status of professional soccer players of F.C. Barcelona and its relation to the incidence of sport lesions. Methods: Thirty professional soccer players were consecutively evaluated in the seasons 2003/4, 2004/5 and 2005/6. A research protocol to assess their oral health was developed. DMFT, Quigley & Hein plaque index (PI), Löe & Silness gingival index (GI), World Health Organization malocclusion index, Ramfjord teeth probing pocket depth (PPD), TMJ examination and history of dental trauma were recorded. All physical injuries sustained by players during the season were documented from F.C. Barcelona medical services. Results: Mean DMFT score was 5.7 (SD 4.1), Quigley & Hein plaque index score was 2.3 (SD 1.1), Löe & Silness gingival index was 1.1 (SD 0.8), and periodontal pocket depth was 1.9 mm (SD 0.3). Pearson"s analysis showed a significant correlation between PI and GI (p<0.01). Nine players (30%) presented bruxism - the same proportion of those with severe malocclusion. Seven (23.3%) players had suffered uncomplicated crown fractures. The mean incidence of physical injuries was 8 (SD 3.4) per player. PI and PPD showed a statistically significant correlation to muscle injuries (p<0.05). Conclusions: Soccer players, despite intensive medical follow-up, have significant oral health problems such as untreated caries, gingivitis or malocclusion, and suffer dental trauma as a result of sports activities. Their physical condition could also be associated to oral health

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Background The effect of maraviroc on the maintenance and the function of HIV-1-specific T cell responses remains unknown. Methods Subjects recently infected with HIV-1 were randomized to receive anti-retroviral treatment with or without maraviroc intensification for 48 weeks, and were monitored up to week 60. PBMC and in vitro-expanded T cells were tested for responses to the entire HIV proteome by ELISpot analyses. Intracellular cytokine staining assays were conducted to monitor the (poly)-functionality of HIV-1-specific T cells. Analyses were performed at baseline and week 24 after treatment start, and at week 60 (3 months after maraviroc discontinuation). Results Maraviroc intensification was associated with a slower decay of virus-specific T cell responses over time compared to the non-intensified regimen in both direct ex-vivo as well as in in-vitro expanded cells. The effector function profiles of virus-specific CD8+ T cells were indistinguishable between the two arms and did not change over time between the groups. Conclusions Maraviroc did not negatively impact any of the measured parameters, but was rather associated with a prolonged maintenance of HIV-1-specific T cell responses. Maraviroc, in addition to its original effect as viral entry inhibitor, may provide an additional benefit on the maintenance of virus-specific T cells which may be especially important for future viral eradication strategies.

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The velocity of dripline flushing in subsurface drip irrigation (SDI) systems affects system design, cost, management, performance, and longevity. A 30‐day field study was conducted at Kansas State University to analyze the effect of four targeted flushing velocities (0.23, 0.30, 0.46, and 0.61 m/s) for a fixed 15 min duration of flushing and three flushing frequencies (no flushing or flushing every 15 or 30 days) on SDI emitter discharge and sediments within the dripline and removed in the flushing water. At the end of the field experiment (371 h), the amount of solids carried away by the flushing water and retained in every lateral were determined as well as laboratory determination of emitter discharge for every single emitter within each dripline. Greater dripline flushing velocities, which also resulted in greater flushing volumes, tended to result in greater amounts of solids in the flushing water, but the differences were not always statistically significant. Neither the frequency of flushing nor the interaction of flushing frequency and velocity significantly affected the amount of solids in the flushing water. There was a greater concentration of solids in the beginning one‐third of the 90 m laterals, particularly for treatments with no flushing or with slower dripline flushing velocities. As flushing velocity and concurrently flushing volume increased, there was a tendency for greater solids removal and/or more equal distribution within the dripline. At the end of the field study, the average emitter discharge as measured in the laboratory for a total of 3970 emitters was 0.64 L/h. which was significantly less (approximately 2.5%) than the discharge for new and unused emitters. Only six emitters were nearly or fully clogged, with discharges between 0% and 5% of new and unused emitters. Flushing velocity and flushing frequency did not have consistent significant effects on emitter discharge, and those numerical differences that did exist were small (<3%). Emitter discharge was approximately 3% less for the distal ends of the driplines (last 20% of the dripline). Although not a specific factor in the study, the results of solids removals during flushing and solids retention within the different dripline sections suggest that duration of flushing may be a more cost‐effective management option than increasing the dripline flushing velocity through SDI system design. Finally, although microirrigation system components have been improved over the years, the need for flushing to remove solids and reduce clogging potential has not been eliminated

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Background: Epidemiologic studies have suggested that flavonoid intake plays a critical role in the prevention of coronary heart disease. Because atherosclerosis is considered a low-grade inflammatory disease, some feeding trials have analyzed the effects of cocoa (an important source of flavonoids) on inflammatory biomarkers, but the results have been controversial. Objective: The objective was to evaluate the effects of chronic cocoa consumption on cellular and serum biomarkers related to atherosclerosis in high-risk patients. Design: Forty-two high-risk volunteers (19 men and 23 women; mean 6 SD age: 69.7 6 11.5 y) were included in a randomized crossover feeding trial. All subjects received 40 g cocoa powder with 500 mL skim milk/d (C+M) or only 500 mL skim milk/d (M) for 4 wk. Before and after each intervention period, cellular and serum inflammatory biomarkers related to atherosclerosis were evaluated. Results: Adherence to the dietary protocol was excellent. No significant changes in the expression of adhesion molecules on T lymphocyte surfaces were found between the C+M and M groups. However, in monocytes, the expression of VLA-4, CD40, and CD36 was significantly lower (P = 0.005, 0.028, and 0.001, respectively) after C+M intake than after M intake. In addition, serum concentrations of the soluble endothelium-derived adhesion molecules P-selectin and intercellular adhesion molecule-1 were significantly lower (both P = 0.007) after C+M intake than after M intake. Conclusions: These results suggest that the intake of cocoa polyphenols may modulate inflammatory mediators in patients at high risk of cardiovascular disease. These antiinflammatory effects may contribute to the overall benefits of cocoa consumption against atherosclerosis. This trial was registered in the Current Controlled Trials at London, International Standard Randomized Controlled Trial Number, at controlled-trials.com as ISRCTN75176807.

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La popularització del Pedraforca com a destinació d"excursionistes, escaladors i curiosos en general fa que la freqüentació hi sigui molt alta, cosa que comporta efectes negatius sobre el medi. Els més evidents i alhora preocupants són els que afecten els hàbitats més fràgils, com és cas dels de la conegudíssima tartera del Pedraforca o de Saldes

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Flushing is an important maintenance task that removes accumulated particles in microirrigation laterals that can help to reduce clogging problems. The effect of three dripline flushing frequency treatments (no flushing, one flushing at the end of each irrigation period, and a monthly flushing during the irrigation period) was studied in surface and subsurface drip irrigation systems that operated using a wastewater treatment plant effluent for three irrigation periods of 540 h each. The irrigation systems had two different emitters, one pressure compensating and the other not, both molded and welded onto the interior dripline wall, placed in laterals 87 meters long. Dripline flow of the pressure compensating emitter increased 8% over time, while in the nonpressure compensating emitter, dripline flow increased 25% in the surface driplines and decreased 3% in the subsurface driplines by the emitter clogging. Emitter clogging was affected primarily by the interactions between emitter location, emitter type, and flushing frequency treatment. The number of completely clogged emitters was affected by the interaction between irrigation system and emitter type. There was an average of 3.7% less totally clogged emitters in flushed surface driplines with the pressurecompensating emitter as compared to flushed subsurface laterals with the nonpressure compensating emitter

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BACKGROUND AND AIMS: Liver stiffness is increasingly used in the non-invasive evaluation of chronic liver diseases. Liver stiffness correlates with hepatic venous pressure gradient (HVPG) in patients with cirrhosis and holds prognostic value in this population. Hence, accuracy in its measurement is needed. Several factors independent of fibrosis influence liver stiffness, but there is insufficient information on whether meal ingestion modifies liver stiffness in cirrhosis. We investigated the changes in liver stiffness occurring after the ingestion of a liquid standard test meal in this population. METHODS: In 19 patients with cirrhosis and esophageal varices (9 alcoholic, 9 HCV-related, 1 NASH; Child score 6.9±1.8), liver stiffness (transient elastography), portal blood flow (PBF) and hepatic artery blood flow (HABF) (Doppler-Ultrasound) were measured before and 30 minutes after receiving a standard mixed liquid meal. In 10 the HVPG changes were also measured. RESULTS: Post-prandial hyperemia was accompanied by a marked increase in liver stiffness (+27±33%; p<0.0001). Changes in liver stiffness did not correlate with PBF changes, but directly correlated with HABF changes (r = 0.658; p = 0.002). After the meal, those patients showing a decrease in HABF (n = 13) had a less marked increase of liver stiffness as compared to patients in whom HABF increased (n = 6; +12±21% vs. +62±29%,p<0.0001). As expected, post-prandial hyperemia was associated with an increase in HVPG (n = 10; +26±13%, p = 0.003), but changes in liver stiffness did not correlate with HVPG changes. CONCLUSIONS: Liver stiffness increases markedly after a liquid test meal in patients with cirrhosis, suggesting that its measurement should be performed in standardized fasting conditions. The hepatic artery buffer response appears an important factor modulating postprandial changes of liver stiffness. The post-prandial increase in HVPG cannot be predicted by changes in liver stiffness.

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The annual elimination of large numbers of Argentine ant queens near the advance front of an invasion could be a useful tool for weakening the species’ dispersion and, therefore, limiting its establishment in non-invaded areas. However, before carrying out trials to test the effectiveness of this method it would be essential to have sufficient knowledge of the effect of seasonal dynamics acting on the queens’ densities of the species in order to determine the most favourable period of the year to act. We analyzed the seasonal densities and nest dynamics of Argentine ant queens in an invaded Mediterranean natural ecosystem. We observed that the queens’ density varied depending on the season of the year and that this variation was mainly due to the seasonal dynamics of nest aggregations in winter and ant dispersions in summer. The greatest densities per litre of nest soil were observed in winter (December to March, approximately) and the lowest densities were observed in summer ( June to July). This information is essential for improving current knowledge of the Argentine ant’s biology and developing control methods based on the elimination of queens in invaded natural areas

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Avui fa una setmana es va cloure la cimera del clima, sense progressos significatius. Quan es discuteix sobre canvi climàtic es posa molt èmfasi en les emissions de gasos d'efecte hivernacle, i es parla de desenvolupament, industrialització i sostenibilitat, però no es té en compte la causa primera de tot això, la nostra idiosincràsia biològica [...].

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Fa dues setmanes vaig parlar de la importància d'assistir a reunions científiques i de les conseqüències ambientals de la recerca. Un treball recent ha analitzat l'impacte d'un congrés al qual van assistir 15.000 especialistes, el desplaçament dels quals va generar 11.000 tones de CO2, les mateixes que emeten 110.000 txadians en un any [...].

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Un dels requisits perquè la ciència avanci és que sigui compartida, a la qual cosa contribueixen les publicacions especialitzades. Tanmateix, els contactes personals són extremadament productius. Aquesta és la finalitat dels congressos i les reunions científiques [...].