985 resultados para electronic stopping power
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Other Audit Report - Utilities
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Triglycerides are transported in plasma by specific triglyceride-rich lipoproteins; in epidemiological studies, increased triglyceride levels correlate with higher risk for coronary artery disease (CAD). However, it is unclear whether this association reflects causal processes. We used 185 common variants recently mapped for plasma lipids (P < 5 × 10(-8) for each) to examine the role of triglycerides in risk for CAD. First, we highlight loci associated with both low-density lipoprotein cholesterol (LDL-C) and triglyceride levels, and we show that the direction and magnitude of the associations with both traits are factors in determining CAD risk. Second, we consider loci with only a strong association with triglycerides and show that these loci are also associated with CAD. Finally, in a model accounting for effects on LDL-C and/or high-density lipoprotein cholesterol (HDL-C) levels, the strength of a polymorphism's effect on triglyceride levels is correlated with the magnitude of its effect on CAD risk. These results suggest that triglyceride-rich lipoproteins causally influence risk for CAD.
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Three-dimensional information is much easier to understand than a set of two-dimensional images. Therefore a layman is thrilled by the pseudo-3D image taken in a scanning electron microscope (SEM) while, when seeing a transmission electron micrograph, his imagination is challenged. First approaches to gain insight in the third dimension were to make serial microtome sections of a region of interest (ROI) and then building a model of the object. Serial microtome sectioning is a tedious and skill-demanding work and therefore seldom done. In the last two decades with the increase of computer power, sophisticated display options, and the development of new instruments, an SEM with a built-in microtome as well as a focused ion beam scanning electron microscope (FIB-SEM), serial sectioning, and 3D analysis has become far easier and faster.Due to the relief like topology of the microtome trimmed block face of resin-embedded tissue, the ROI can be searched in the secondary electron mode, and at the selected spot, the ROI is prepared with the ion beam for 3D analysis. For FIB-SEM tomography, a thin slice is removed with the ion beam and the newly exposed face is imaged with the electron beam, usually by recording the backscattered electrons. The process, also called "slice and view," is repeated until the desired volume is imaged.As FIB-SEM allows 3D imaging of biological fine structure at high resolution of only small volumes, it is crucial to perform slice and view at carefully selected spots. Finding the region of interest is therefore a prerequisite for meaningful imaging. Thin layer plastification of biofilms offers direct access to the original sample surface and allows the selection of an ROI for site-specific FIB-SEM tomography just by its pronounced topographic features.
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Aging adults represent the fastest growing population segment in many countries. Physiological and metabolic changes in the aging process may alter how aging adults biologically respond to pollutants. In a controlled human toxicokinetic study (exposure chamber; 12 m³), aging volunteers (n=10; >58 years) were exposed to propylene glycol monomethyl ether (PGME, CAS no. 107-98-2) at 50 ppm for 6 h. The dose-dependent renal excretion of oxidative metabolites, conjugated and free PGME could potentially be altered by age. AIMS: (1) Compare PGME toxicokinetic profiles between aging and young volunteers (20-25 years) and gender; (2) test the predictive power of a compartmental toxicokinetic (TK) model developed for aging persons against urinary PGME concentrations found in this study. METHODS: Urine samples were collected before, during, and after the exposure. Urinary PGME was quantified by capillary GC/FID. RESULTS: Differences in urinary PGME profiles were not noted between genders but between age groups. Metabolic parameters had to be changed to fit the age adjusted TK model to the experimental results, implying a slower enzymatic pathway in the aging volunteers. For an appropriate exposure assessment, urinary total PGME should be quantified. CONCLUSION: Age is a factor that should be considered when biological limit values are developed.
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PURPOSE: Repeated-sprint training in hypoxia (RSH) was recently shown to improve repeated-sprint ability (RSA) in cycling. This phenomenon is likely to reflect fiber type-dependent, compensatory vasodilation, and therefore, our hypothesis was that RSH is even more beneficial for activities involving upper body muscles, such as double poling during cross-country skiing. METHODS: In a double-blinded fashion, 17 competitive cross-country skiers performed six sessions of repeated sprints (each consisting of four sets of five 10-s sprints, with 20-s intervals of recovery) either in normoxia (RSN, 300 m; FiO2, 20.9%; n = 8) or normobaric hypoxia (RSH, 3000 m; FiO2, 13.8 %; n = 9). Before (pre) and after (post) training, performance was evaluated with an RSA test (10-s all-out sprints-20-s recovery, until peak power output declined by 30%) and a simulated team sprint (team sprint, 3 × 3-min all-out with 3-min rest) on a double-poling ergometer. Triceps brachii oxygenation was measured by near-infrared spectroscopy. RESULTS: From pretraining to posttraining, peak power output in the RSA was increased (P < 0.01) to the same extent (29% ± 13% vs 26% ± 18%, nonsignificant) in RSH and in RSN whereas the number of sprints performed was enhanced in RSH (10.9 ± 5.2 vs 17.1 ± 6.8, P < 0.01) but not in RSN (11.6 ± 5.3 vs 11.7 ± 4.3, nonsignificant). In addition, the amplitude in total hemoglobin variations during sprints throughout RSA rose more in RSH (P < 0.01). Similarly, the average power output during all team sprints improved by 11% ± 9% in RSH and 15% ± 7% in RSN. CONCLUSIONS: Our findings reveal greater improvement in the performance of repeated double-poling sprints, together with larger variations in the perfusion of upper body muscles in RSH compared with those in RSN.
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Lector de comics para plataforma iOS para dispositivos iPad.
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Fertility has unanimously declined across the entire post-communist region. This study explores the variation in fertility trends over time among these countries and assesses to what degree three explanations are applicable: second demographic transition (SDT), postponement transition (PPT) or reaction to the economic crisis. Moreover, on the basis of SDT and PPT theoretical tenets, as well as descriptive evidence, the economic context is hypothesized to be linked to two processes of fertility decline conversely. The results show that no one theoretical explanation is sufficient to explain the complex fertility declines across the entire post-communist region from 1990 to 2003. In some countries, a great part of the decline in fertility occurred before significant postponement of childbearing began, which indicates that the dramatic decline was due to stopping behavior or postponement of higher order births. Postponement of first births, either through PPT or SDT processes, greatly contributed to fertility decline in a small number of countries. Pooled cross-sectional time-series analyses of age-specific birthrates confirm that these two distinct processes are present and show that the economic crisis explanation has explanatory power for declining birth rates. In contrast, logistic regressions show that the likelihood of postponing childbirth increases with improved economic conditions. These results confirm the importance of taking the economic context into account when discussing explanations for fertility decline. More specifically, the results indicate that the severity and duration of economic crisis, or absence thereof, influenced the extent and manner in which fertility declined.
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Blood pressure (BP) is a heritable, quantitative trait with intraindividual variability and susceptibility to measurement error. Genetic studies of BP generally use single-visit measurements and thus cannot remove variability occurring over months or years. We leveraged the idea that averaging BP measured across time would improve phenotypic accuracy and thereby increase statistical power to detect genetic associations. We studied systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP) averaged over multiple years in 46,629 individuals of European ancestry. We identified 39 trait-variant associations across 19 independent loci (p < 5 × 10(-8)); five associations (in four loci) uniquely identified by our LTA analyses included those of SBP and MAP at 2p23 (rs1275988, near KCNK3), DBP at 2q11.2 (rs7599598, in FER1L5), and PP at 6p21 (rs10948071, near CRIP3) and 7p13 (rs2949837, near IGFBP3). Replication analyses conducted in cohorts with single-visit BP data showed positive replication of associations and a nominal association (p < 0.05). We estimated a 20% gain in statistical power with long-term average (LTA) as compared to single-visit BP association studies. Using LTA analysis, we identified genetic loci influencing BP. LTA might be one way of increasing the power of genetic associations for continuous traits in extant samples for other phenotypes that are measured serially over time.
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BACKGROUND AND PURPOSE: The ASTRAL score was externally validated showing remarkable consistency on 3-month outcome prognosis in patients with acute ischemic stroke. The present study aimed to evaluate ASTRAL score's prognostic accuracy to predict 5-year outcome. METHODS: All consecutive patients with acute ischemic stroke registered in the Athens Stroke Registry between January 1, 1998, and December 31, 2010, were included. Patients were excluded if admitted >24 hours after symptom onset or if any ASTRAL score component was missing. End points were 5-year unfavorable functional outcome, defined as modified Rankin Scale 3 to 6, and 5-year mortality. For each outcome, the area under the receiver operating characteristics curve was calculated; also, a multivariate Cox proportional hazards analysis was performed to investigate whether the ASTRAL score was an independent predictor of outcome. The Kaplan-Meier product limit method was used to estimate the probability of 5-year survival for each ASTRAL score quartile. RESULTS: The area under the receiver operating characteristics curve of the score to predict 5-year unfavorable functional outcome was 0.89, 95% confidence interval 0.88 to 0.91. In multivariate Cox proportional hazards analysis, the ASTRAL score was independently associated with 5-year unfavorable functional outcome (hazard ratio, 1.09; 95% confidence interval, 1.08-1.10). The area under the receiver operating characteristics curve for the ASTRAL score's discriminatory power to predict 5-year mortality was 0.81 (95% confidence interval, 0.78-0.83). In multivariate analysis, the ASTRAL score was independently associated with 5-year mortality (hazard ratio, 1.09, 95% confidence interval, 1.08-1.10). During the 5-year follow-up, the probability of survival was significantly lower with increasing ASTRAL score quartiles (log-rank test <0.001). CONCLUSIONS: The ASTRAL score reliably predicts 5-year functional outcome and mortality in patients with acute ischemic stroke.
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Sleep deprivation (SD) results in increased electroencephalographic (EEG) delta power during subsequent non-rapid eye movement sleep (NREMS) and is associated with changes in the expression of circadian clock-related genes in the cerebral cortex. The increase of NREMS delta power as a function of previous wake duration varies among inbred mouse strains. We sought to determine whether SD-dependent changes in circadian clock gene expression parallel this strain difference described previously at the EEG level. The effects of enforced wakefulness of incremental durations of up to 6 h on the expression of circadian clock genes (bmal1, clock, cry1, cry2, csnk1epsilon, npas2, per1, and per2) were assessed in AKR/J, C57BL/6J, and DBA/2J mice, three strains that exhibit distinct EEG responses to SD. Cortical expression of clock genes subsequent to SD was proportional to the increase in delta power that occurs in inbred strains: the strain that exhibits the most robust EEG response to SD (AKR/J) exhibited dramatic increases in expression of bmal1, clock, cry2, csnkIepsilon, and npas2, whereas the strain with the least robust response to SD (DBA/2) exhibited either no change or a decrease in expression of these genes and cry1. The effect of SD on circadian clock gene expression was maintained in mice in which both of the cryptochrome genes were genetically inactivated. cry1 and cry2 appear to be redundant in sleep regulation as elimination of either of these genes did not result in a significant deficit in sleep homeostasis. These data demonstrate transcriptional regulatory correlates to previously described strain differences at the EEG level and raise the possibility that genetic differences underlying circadian clock gene expression may drive the EEG differences among these strains.
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Expressions relating spectral efficiency, power, and Doppler spectrum, are derived for Rayleigh-faded wireless channels with Gaussian signal transmission. No side information on the state of the channel is assumed at the receiver. Rather, periodic reference signals are postulated in accordance with the functioning of most wireless systems. The analysis relies on a well-established lower bound, generally tight and asymptotically exact at low SNR. In contrast with most previous studies, which relied on block-fading channel models, a continuous-fading model is adopted. This embeds the Doppler spectrum directly in the derived expressions, imbuing them with practical significance. Closed-form relationships are obtained for the popular Clarke-Jakes spectrum and informative expansions, valid for arbitrary spectra, are found for the low- and high-power regimes. While the paper focuses on scalar channels, the extension to multiantenna settings is also discussed.
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The mutual information of independent parallel Gaussian-noise channels is maximized, under an average power constraint, by independent Gaussian inputs whose power is allocated according to the waterfilling policy. In practice, discrete signalling constellations with limited peak-to-average ratios (m-PSK, m-QAM, etc) are used in lieu of the ideal Gaussian signals. This paper gives the power allocation policy that maximizes the mutual information over parallel channels with arbitrary input distributions. Such policy admits a graphical interpretation, referred to as mercury/waterfilling, which generalizes the waterfilling solution and allows retaining some of its intuition. The relationship between mutual information of Gaussian channels and nonlinear minimum mean-square error proves key to solving the power allocation problem.
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The analysis of the multiantenna capacity in the high-SNR regime has hitherto focused on the high-SNR slope (or maximum multiplexing gain), which quantifies the multiplicative increase as function of the number of antennas. This traditional characterization is unable to assess the impact of prominent channel features since, for a majority of channels, the slope equals the minimum of the number of transmit and receive antennas. Furthermore, a characterization based solely on the slope captures only the scaling but it has no notion of the power required for a certain capacity. This paper advocates a more refined characterization whereby, as function of SNRjdB, the high-SNR capacity is expanded as an affine function where the impact of channel features such as antenna correlation, unfaded components, etc, resides in the zero-order term or power offset. The power offset, for which we find insightful closed-form expressions, is shown to play a chief role for SNR levels of practical interest.
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This paper formulates power allocation policies that maximize the region of mutual informationsachievable in multiuser downlink OFDM channels. Arbitrary partitioning ofthe available tones among users and arbitrary modulation formats, possibly different forevery user, are considered. Two distinct policies are derived, respectively for slow fadingchannels tracked instantaneously by the transmitter and for fast fading channels knownonly statistically thereby. With instantaneous channel tracking, the solution adopts theform of a multiuser mercury/waterfilling procedure that generalizes the single-user mercury/waterfilling introduced in [1, 2]. With only statistical channel information, in contrast,the mercury/waterfilling interpretation is lost. For both policies, a number of limitingregimes are explored and illustrative examples are provided.