682 research outputs found

    The effects of androstenedione supplementation on testosterone levels, exercise performance, and mood in older males

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    The primary purpose of this study, therefore, was to determine if androstenedione supplementation alters testosterone in older men, who have lower natural testosterone levels than younger counterparts. A secondary purpose was to determine if the supplement altered mood, perceived exertion, or testosterone levels with exercise. [This is an excerpt from the abstract. For the complete abstract, please see the document.

    Analytical approximation to the multidimensional Fokker--Planck equation with steady state

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    The Fokker--Planck equation is a key ingredient of many models in physics, and related subjects, and arises in a diverse array of settings. Analytical solutions are limited to special cases, and resorting to numerical simulation is often the only route available; in high dimensions, or for parametric studies, this can become unwieldy. Using asymptotic techniques, that draw upon the known Ornstein--Uhlenbeck (OU) case, we consider a mean-reverting system and obtain its representation as a product of terms, representing short-term, long-term, and medium-term behaviour. A further reduction yields a simple explicit formula, both intuitive in terms of its physical origin and fast to evaluate. We illustrate a breadth of cases, some of which are `far' from the OU model, such as double-well potentials, and even then, perhaps surprisingly, the approximation still gives very good results when compared with numerical simulations. Both one- and two-dimensional examples are considered.Comment: Updated version as publishe

    Simulation Supported Estimation of End-to-End Transmission Parameters in Non-Viral Gene Delivery

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    Communications, in general, involve delivery of information from a source to a sink. At nano-scale, an example of a man-made communications involving interfacing with biological systems at intra-cellular level is non-viral gene delivery. From a telecommunications engineering perspective, important end-to-end parameters of such a system are: the endto- end delay, system capacity, and packet loss rate. There are neither known methods to estimate those parameters theoretically nor they are ready available from standard measurements. The paper provides estimates for those parameters based on the simulation of non-viral gene delivery system based on the queuing theory. The simulator used has been validated through the series of in-vitro laboratory experiments

    Regional and Hemispheric Determinants of Language Laterality: Implications for Preoperative fMRI

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    Language is typically a function of the left hemisphere but the right hemisphere is also essential in some healthy individuals and patients. This inter-subject variability necessitates the localization of language function, at the individual level, prior to neurosurgical intervention. Such assessments are typically made by comparing left and right hemisphere language function to determine “language lateralization” using clinical tests or fMRI. Here, we show that language function needs to be assessed at the region and hemisphere specific level, because laterality measures can be misleading. Using fMRI data from 82 healthy participants, we investigated the degree to which activation for a semantic word matching task was lateralized in 50 different brain regions and across the entire cortex. This revealed two novel findings. First, the degree to which language is lateralized across brain regions and between subjects was primarily driven by differences in right hemisphere activation rather than differences in left hemisphere activation. Second, we found that healthy subjects who have relatively high left lateralization in the angular gyrus also have relatively low left lateralization in the ventral precentral gyrus. These findings illustrate spatial heterogeneity in language lateralization that is lost when global laterality measures are considered. It is likely that the complex spatial variability we observed in healthy controls is more exaggerated in patients with brain damage. We therefore highlight the importance of investigating within hemisphere regional variations in fMRI activation, prior to neuro-surgical intervention, to determine how each hemisphere and each region contributes to language processing. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc

    Cardiac and arterial interactions in end-stage renal disease

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    Cardiac and arterial interactions in end-stage renal disease. Although cardiac hypertrophy is a frequent complication of end-stage renal disease (ESRD), relatively little is known about large arterial geometry and function in vivo in these patients, and the relationship between arterial changes and cardiac hypertrophy is unknown. Common carotid artery (CCA) intima-media thickness and internal diameter and left ventricular geometry and function were determined by ultrasound imaging in 70 uncomplicated ESRD patients and in 50 age-, sex-, and blood pressure-matched controls. Arterial distensibility and compliance were determined from simultaneously recorded CCA diameter and stroke changes in diameter and CCA pressure waveforms, obtained by applanation tonometry, and also by the measurement of carotid-femoral pulse wave velocity. Compared with control subjects, ESRD patients had greater left ventricular diameter (P < 0.01), wall thicknesses and mass (P < 0.001), increased CCA diameter (6.25 ± 0.87 vs. 5.55 ± 0.65 mm; P < 0.001), larger CCA intima-media thickness (777 ± 115 vs. 678 ± 105 ” m; P < 0.001) and intima-media cross-sectional area (17.5 ± 4.5 vs. 13.4 ± 3.3mm2; P < 0.001). In uremic patients, arterial hypertrophy was associated with decreased CCA distensibility (17.8 ± 8.8 vs. 24.0 ± 12.7kPa−1 · 10−3; P < 0.001) and compliance (5.15 ± 2 vs. 6.0 ± 2.5m2 · kPa−1 · 10−7; P < 0.05), accelerated carotid-femoral pulse wave velocity (1055 ± 290 vs. 957 ± 180 cm/seconds; P < 0.001), early return and increased effect of arterial wave reflections (20.5 ± 15.4 vs. 9.2 ± 18.4%; P < 0.001). The latter phenomenons were responsible for increased pulsatile pressure load in CCA (58.3 ± 21 vs. 48 ± 17mm Hg; P < 0.01) and were associated with a decreased subendocardial viability index (157 ± 31 vs. 173 ± 30%; P < 0.001). The CCA diameter was correlated with the left ventricular diameter (P < 0.01), and a significant correlations existed between CCA wall thickness or CCA intima-media cross-sectional area and left ventricular wall thicknesses and/or left ventricular mass (P < 0.01). In multivariate analysis, these relationships were independent regarding age, sex, blood pressure and body surface area. The present study documents parallel cardiac and vascular adaptation in ESRD, and demonstrates the potential contribution of structural and functional large artery alterations to the pathogenesis of left ventricular hypertrophy and functional alterations

    Approche multifactorielle et typologique du concept de fragilitĂ© chez les patients hypertendus non contrĂŽlĂ©s. EnquĂȘte Eclat

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    Objective The aim of the Eclat survey was to evaluate the frequency of frailty in uncontrolled hypertensives and to individualize different frailty profiles. Patients and methods This was an observational, prospective, longitudinal survey conducted in the cohort of uncontrolled hypertensive patients aged 55 years or more. Morbid events having occurred between two visits at a 6-month interval were reported. Patients with at least one event were considered to be frail. Predictive factors of at least one event were identified (logistic regression). The analysis was completed by a typological analysis (principal components analysis and clustering). Results At least one event occurred in 211 (9%) of 2306 patients (males 55%, 67 ± 9 years old, blood pressure [BP] = 160 ± 11/93 ± 8 mmHg, diabetes 23%): cardiovascular (1.7%), gerontological (5.5%), onset of diabetes (1.3%), worsening of renal impact (2%). Three frailty profiles were identified: patients at low risk (n = 1507, event rate = 6%), with neither cardiovascular risk factors nor target organ damage; patients at moderate risk (n = 335, event rate = 12%) with numerous risk factors but no target organ damage and patients at high risk (n = 243, event rate = 23%), the older ones, in bad general condition, with target organ damage, sensorial deficits and cognitive disorders. In a population of uncontrolled hypertensives aged 55 years or more, 9% could be considered as frailty. Conclusion Therapeutic measures might be adapted according to the frailty profile of the patient. With respect to treatment management, healthcare behaviour could differ depending on these frailty profiles

    Carcass characteristics and beef quality of young grass-fed Angus x Salers bovines

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    To characterize carcass and meat attributes, such as beef eating quality in specific farming conditions, 31 young grass-fed crossbred Angus x Salers cattle in two farming systems (a mono-cattle system versus a mixed system with beef cattle and sheep) were used in this study. Three muscle cuts (striploin—m. longissimus dorsi et thoracis; bolar blade—m. triceps brachii caput longum; internal flank plate—m. obliquus internus abdominis) were used for consumer eating quality testing and striploin was used for panelist eating quality assessment, and objective measurements [Warner–Bratzler shear force (WBSF) and fatty acid (FA) and antioxidant contents]. Results indicated that the farming system had no impact on carcass characteristics or meat quality, but it tended to affect FA content, which is likely explained by between-system differences in animal maturity (assessed by ossification score). Animal gender had significant effects on three eating quality traits evaluated by untrained consumers, with higher flavor liking, overall liking, and overall meat eating quality (MQ4) scores in females than in males. Additionally, FA contents were correlated with sensory quality traits to varying extents: consumer-scored tenderness, flavor, and overall liking were mainly positively correlated with ω-3 and ω-6 polyunsaturated fatty acid (PUFA) contents, and panelist-evaluated tenderness and abnormal flavor were more positively correlated with total lipids, saturated fatty acid (SFA), and monounsaturated fatty acid (MUFA) contents. Overall, this study showed that specific grass-fed crossbred Angus x Salers cattle can produce lean meat rich in ω-3 PUFAs with a low ω-6/ω-3 ratio and with “better than average” beef eating quality

    Physical mechanisms and parameters for models of microstructure evolution under irradiation in Fe alloys – Part I: Pure Fe

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    This paper is the first of three that overview the main mechanisms that drive the microstructure evolution in Fe alloys under irradiation. It focuses on pure α-Fe and compiles the parameters that describe quantitatively the mobility and stability of point-defects and especially their clusters, including possible reactions and criteria to decide when they should react. These parameters are the result of several years of calculations and application in microstructure evolution models. They are mainly collected from the literature and the parameter choice tries to reconcile different sets of values that, while being in general qualitatively similar, are often quantitatively not coincident. A few calculation results are presented here for the first time to support specific approximations concerning defect properties or features. Since calculations cannot cover all possible defect configurations, the definition of these parameters often requires educated guesses to fill knowledge gaps. These guesses are here listed and discussed whenever relevant. This is therefore a “hands-on” paper that: (i) collects in a single report most microstructure evolution parameters that are found in the literature for irradiated α-Fe, including a discussion of the most important mechanisms at play based on current knowledge; (ii) selects a ready-to-use set that can be employed in microstructure evolution models, such as those based on object kinetic Monte Carlo (OKMC) methods. This work also identifies parameters that are needed, but not known, hopefully prompting corresponding calculations in the future.This work has received funding from the Euratom research and training programme 2014-2018 under grant agreement No. 755039 (M4F project). This research also contributes to the Joint Programme on Nuclear Materials of the European Energy Research Alliance (EERA-JPNM)

    Typology of seismic motion and seismic engineering design

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    The paper deals with the influence of the seismic motion typology on the structural response and with engineering design under exceptional actions. Various aspects of seismic motion typology that lead to exceptional actions on the structures are covered. The influence of near fault ground motions, the effect of local site parameters and the magnification of the seismic action on short-period structures are among the parameters identified as dominant for the structural response. The paper presents also a methodology for handling uncertainty in engineering design, based on the mathematical framework of fuzzy analysis. Finally the paper presents various applications of performance based design, which is viewed as a tool as a tool for the analysis of structural behaviour under extreme seismic events. The influence of connection behaviour on the structural response is studied, and applications of the capacity design methodology and of the direct displacement design approach for the evaluation of reinforce concrete structures are presented
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