994 resultados para Barrier performance


Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study examined the effects of intermittent hypoxic training (IHT) on skeletal muscle monocarboxylate lactate transporter (MCT) expression and anaerobic performance in trained athletes. Cyclists were assigned to two interventions, either normoxic (N; n = 8; 150 mmHg PIO2) or hypoxic (H; n = 10; ∼3000 m, 100 mmHg PIO2) over a three week training (5×1 h-1h30.week-1) period. Prior to and after training, an incremental exercise test to exhaustion (EXT) was performed in normoxia together with a 2 min time trial (TT). Biopsy samples from the vastus lateralis were analyzed for MCT1 and MCT4 using immuno-blotting techniques. The peak power output (PPO) increased (p<0.05) after training (7.2% and 6.6% for N and H, respectively), but VO2max showed no significant change. The average power output in the TT improved significantly (7.3% and 6.4% for N and H, respectively). No differences were found in MCT1 and MCT4 protein content, before and after the training in either the N or H group. These results indicate there are no additional benefits of IHT when compared to similar normoxic training. Hence, the addition of the hypoxic stimulus on anaerobic performance or MCT expression after a three-week training period is ineffective.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Intensification of farming over the past 50 years has homogenised the landscape structure and contributed to the decline of bird populations in Europe. To better target the conservation of the Barn Owl Tyto alba, we assessed the influence of the landscape structure on breeding performance in western Switzerland. The analyses considered a 23-year data set of breeding parameters collected in an area dominated by intensive agriculture. Using a Geographic Information System approach, landscape characteristics were described around 194 nest sites. Our analyses showed that nest-box occupancy, laying date, clutch and brood size, egg volume and probability of producing a second annual clutch were not significantly associated with any of the eight principal landscape variables (agricultural land, woodland, urban area, hedgerows, cereals, sugar beet, maize and meadow). Nevertheless, the probability that a breeding pair occupied a nest-box decreased the more roads there were surrounding the nest-box. The absence of strong associations between habitat features and breeding parameters suggests that prey availability may be relatively similar between the different breeding sites. In our study area Barn Owls can always find suitable foraging habitats around most nest-boxes.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The following hypotheses were tested for groups of simultaneous hermaphrodites Biomphalaria tenagophila: (a) snails that have low reproductive success during the process of self-fertilization do not increase their reproductive success after the end of grouping; (b) the copulation behaviour and the presence of one snail whose eggs have a low viability rate influence the partner's reproductive success by cross-fertilization. Groups were constituted by a homozygous pigmented snail and two albinos: one with a viability rate higher than 70% ("good reproducers") and the other less than 10% ("bad reproducers"). All pigmented snails had viability rates higher than 70%. The "good" and "bad" reproducer albino snails had similar copulation behaviour. However, after the end of grouping, the "bad reproducers" continued to have viability rates less than 10% over 30 days. In 100% of the cases that pigmented snails copulated (performing either a male role or simultaneously male and female roles) exclusively with "good" reproducer albinos, they presented high reproductive success (producing, on average of 8.4 pigmented embryos/egg-mass). However, in 100% of the cases that pigmented snails copulated with both partners, the "good" reproducer albino snails produced none or very few embryos (the highest average was 2.2 pigmented embryos/egg-mass). Therefore, the production of viable embryos by cross-fertilization was more influenced by self-fertilization performance than by copulation behaviour. The presence of a snail whose eggs have a low viability rate could decrease their partners reproductive success

Relevância:

20.00% 20.00%

Publicador:

Resumo:

En aquest treball s'analitza la performance econòmica aconseguida per totes les províncies espanyoles i italianes entre 1999 i 2007 a través de deu indicadors econòmics. L'objectiu principal d'aquest estudi és poder establir un rànquing econòmic a nivell NUTS-3 d'ambdues nacions, per després poder il.lustrar les seves estructures econòmiques mitjançant gràfics decagonals que facilitin la interpretació de les distàncies comparatives entre les províncies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Cannula design is of prime importance for venous drainage during cardiopulmonary bypass (CPB). To evaluate cannulas intended for CPB, an in vitro circuit was set up with silicone tubing between the test cannula encased in a movable preload reservoir and another static reservoir. The pressure-drop (DeltaP) value (P-drainage - P-preload) was measured using Millar pressure transducers. Flow rate (Q) was measured using an ultrasound flowmeter. Data display and data recording were controlled using a LabView application, custom made particularly for our experiments. Our results demonstrated that DeltaP, Q, and cannula resistance (DeltaP/Q) values were significantly decreased when the cannula diameter was increased for Smart and Medtronic cannulas. Smartcanula showed 36% and 43% less resistance compared to Medtronic venous and Medtronic femoral cannulas, respectively. The cannula shape (straight- or curved-tips) did not affect the DLP cannula resistance. Out of five cannulas tested, the Smartcanula outperforms the other commercially available cannulas. The mean (DeltaP/Q) values were 3.3 +/- 0.08, 4.07 +/- 0.08, 5.58 +/- 0.10, 5.74 +/- 0.15, and 6.45 +/- 0.15 for Smart, Medtronic, Edwards, Sarns, and Gambro cannulas, respectively (two-way ANOVA, p < 0.0001). In conclusion, the present assay allows discrimination between different forms of cannula with high or low lumen resistance.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The objective of this study was to evaluate the effect of vaccination against GnRH on performance traits, pig behaviour and acute phase proteins. A total of 120 pigs (36 non-castrated males, NCM; 36 males to be vaccinated, IM; 24 castratedmales, CM; and 24 females, FE)were controlled in groups of 12 in pens with feeding stations allowing the recording of individual feed intake. The two vaccinations (Improvac®) were applied at a mean age of 77 and 146 days. All pigswere individually weighed every 3 weeks from the mean ages of 74 to 176 days and backfat thickness (BT) and loinmuscle depth (LD) were also recorded ultrasonically. Twelve group-housed pigs for each treatment were video recorded during 2 consecutive days at weeks 9, 11, 20, 21, 23 and 25 of age to score the number of inactive or active pigs in each treatment group by scan sampling. Aggressive behaviour by the feeder and away from the feeder, and mounting behaviour was also scored by focal sampling. Blood samples from 12 NCM, 12 CM and 12 IM were taken to determine the concentration of circulating acute phase protein Pig-MAP atweeks 1, 2, 4, 11, 13, 21 and 25 of age. After slaughter, the number of skin lesions on the left half carcasswas scored. IMpresented overall a higher growth rate and daily feed intake compared to NCM (Pb0.05),whereas their feed conversion ratios did not differ significantly. In comparison with CM, IM presented a better feed conversion ratio (Pb0.05), since their overall dailyweight gaindid not differ significantly, butIM ate less. Final leanmeat percentage of IM and CM was lower compared to that of NCM (Pb0.05). Activity, mounting and aggressive behaviour of NCM was higher than in IM, CM and FE after the second vaccination. Pig-MAP concentrationswere significantly elevated just after surgical castrationand after bothadministrations of the vaccine (Pb0.05), but concentrations subsequently decreased throughout time. Skin lesions of NCM were significantly higher compared to that of IM and FE (Pb0.05). The effects of vaccination were especially remarkable after the second dose, when the higher feed intake and lower activity of IM compared to NCMmight result in higher final body weight and more fat. Results from this study indicate that some welfare aspects such as a reduced aggression and mounting behaviour may be improved by vaccination against GnRH, together with productive benefits like adequate feed conversion ratio and daily weight gain.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Errors in the inferred multiple sequence alignment may lead to false prediction of positive selection. Recently, methods for detecting unreliable alignment regions were developed and were shown to accurately identify incorrectly aligned regions. While removing unreliable alignment regions is expected to increase the accuracy of positive selection inference, such filtering may also significantly decrease the power of the test, as positively selected regions are fast evolving, and those same regions are often those that are difficult to align. Here, we used realistic simulations that mimic sequence evolution of HIV-1 genes to test the hypothesis that the performance of positive selection inference using codon models can be improved by removing unreliable alignment regions. Our study shows that the benefit of removing unreliable regions exceeds the loss of power due to the removal of some of the true positively selected sites.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We investigated the use of in situ implant formation that incorporates superparamagnetic iron oxide nanoparticles (SPIONs) as a form of minimally invasive treatment of cancer lesions by magnetically induced local hyperthermia. We developed injectable formulations that form gels entrapping magnetic particles into a tumor. We used SPIONs embedded in silica microparticles to favor syringeability and incorporated the highest proportion possible to allow large heating capacities. Hydrogel, single-solvent organogel and cosolvent (low-toxicity hydrophilic solvent) organogel formulations were injected into human cancer tumors xenografted in mice. The thermoreversible hydrogels (poloxamer, chitosan), which accommodated 20% w/v of the magnetic microparticles, proved to be inadequate. Alginate hydrogels, however, incorporated 10% w/v of the magnetic microparticles, and the external gelation led to strong implants localizing to the tumor periphery, whereas internal gelation failed in situ. The organogel formulations, which consisted of precipitating polymers dissolved in single organic solvents, displayed various microstructures. A 8% poly(ethylene-vinyl alcohol) in DMSO containing 40% w/v of magnetic microparticles formed the most suitable implants in terms of tumor casting and heat delivery. Importantly, it is of great clinical interest to develop cosolvent formulations with up to 20% w/v of magnetic microparticles that show reduced toxicity and centered tumor implantation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Report for the scientific sojourn at the the Philipps-Universität Marburg, Germany, from september to december 2007. For the first, we employed the Energy-Decomposition Analysis (EDA) to investigate aromaticity on Fischer carbenes as it is related through all the reaction mechanisms studied in my PhD thesis. This powerful tool, compared with other well-known aromaticity indices in the literature like NICS, is useful not only for quantitative results but also to measure the degree of conjugation or hyperconjugation in molecules. Our results showed for the annelated benzenoid systems studied here, that electron density is more concentrated on the outer rings than in the central one. The strain-induced bond localization plays a major role as a driven force to keep the more substituted ring as the less aromatic. The discussion presented in this work was contrasted at different levels of theory to calibrate the method and ensure the consistency of our results. We think these conclusions can also be extended to arene chemistry for explaining aromaticity and regioselectivity reactions found in those systems.In the second work, we have employed the Turbomole program package and density-functionals of the best performance in the state of art, to explore reaction mechanisms in the noble gas chemistry. Particularly, we were interested in compounds of the form H--Ng--Ng--F (where Ng (Noble Gas) = Ar, Kr and Xe) and we investigated the relative stability of these species. Our quantum chemical calculations predict that the dixenon compound HXeXeF has an activation barrier for decomposition of 11 kcal/mol which should be large enough to identify the molecule in a low-temperature matrix. The other noble gases present lower activation barriers and therefore are more labile and difficult to be observable systems experimentally.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Our empirical literature review shows that little is known about how firm performance changes with age, presumably because of the paucity of data on firm age. For Spanish manufacturing firms, we analyse the firm performance related to firm age between 1998 and 2006. We find evidence that firms improve with age, because ageing firms are observed to have steadily increasing levels of productivity, higher profits, larger size, lower debt ratios, and higher equity ratios. Furthermore, older firms are better able to convert sales growth into subsequent growth of profits and productivity. On the other hand, we also found evidence that firm performance deteriorates with age. Older firms have lower expected growth rates of sales, profits and productivity, they have lower profitability levels (when other variables such as size are controlled for), and also that they appear to be less capable to convert employment growth into growth of sales, profits and productivity. Keywords: firm age, firm growth, LAD, financial structure, vector autoregression JEL CODES: L25, L20

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Summary Report September 1996

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of the present study was to investigate whether trainees' performance on a virtual reality angled laparoscope navigation task correlates with scores obtained on a validated conventional test of spatial ability. 56 participants of a surgery workshop performed an angled laparoscope navigation task on the Xitact LS 500 virtual reality Simulator. Performance parameters were correlated with the score of a validated paper-and-pencil test of spatial ability. Performance at the conventional spatial ability test significantly correlated with performance at the virtual reality task for overall task score (p < 0.001), task completion time (p < 0.001) and economy of movement (p = 0.035), not for endoscope travel speed (p = 0.947). In conclusion, trainees' performance in a standardized virtual reality camera navigation task correlates with their innate spatial ability. This VR session holds potential to serve as an assessment tool for trainees.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This project deals with the generation of profitability and the distribution of its benefits. Inspired by Davis (1947, 1955), we define profitability as the ratio of revenue to cost. Profitability is not as popular a measure of business financial performance as profit, the difference between revenue and cost. Regardless of its popularity, however, profitability is surely a useful financial performance measure. Our primary objective in this project is to identify the factors that generate change in profitability. One set of factors, which we refer to as sources, consists of changes in quantities and prices of outputs and inputs. Individual quantity changes aggregate to the overall impact of quantity change on profitability change, which we call productivity change. Individual price changes aggregate to the overall impact of price change on profitability change, which we call price recovery change. In this framework profitability change consists exclusively of productivity change and price recovery change. A second set of factors, which we refer to as drivers, consists of phenomena such as technical change, change in the efficiency of resource allocation, and the impact of economies of scale. The ability of management to harness these factors drives productivity change, which is one component of profitability change. Thus the term sources refers to quantities and prices of individual outputs and inputs, whose changes influence productivity change or price recovery change, either of which influences profitability change. The term drivers refers to phenomena related to technology and management that influence productivity change (but not price recovery change), and hence profitability change.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The cuticle is a physical barrier that prevents water loss and protects against irradiation, xenobiotics and pathogens. This classic textbook statement has recently been revisited and several observations were made showing that this dogma falls short of being universally true. Both transgenic Arabidopsis thaliana lines expressing cell wall-targeted fungal cutinase (so-called CUTE plants) or lipase as well as several A. thaliana mutants with altered cuticular structure remained free of symptoms after an inoculation with Botrytis cinerea. The alterations in cuticular structure lead to the release of fungitoxic substances and changes in gene expression that form a multifactorial defence response. Several models to explain this syndrome are discussed.