36 resultados para Reduce physical models


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The Plasma and Supra-Thermal Ion Composition (PLASTIC) instrument is one of four experiment packages on board of the two identical STEREO spacecraft A and B, which were successfully launched from Cape Canaveral on 26 October 2006. During the two years of the nominal STEREO mission, PLASTIC is providing us with the plasma characteristics of protons, alpha particles, and heavy ions. PLASTIC will also provide key diagnostic measurements in the form of the mass and charge state composition of heavy ions. Three measurements (E/qk, time of flight, ESSD) from the pulse height raw data are used to characterize the solar wind ions from the solar wind sector, and part of the suprathermal particles from the wide-angle partition with respect to mass, atomic number and charge state. In this paper, we present a new method for flight data analysis based on simulations of the PLASTIC response to solar wind ions. We present the response of the entrance system / energy analyzer in an analytical form. Based on stopping power theory, we use an analytical expression for the energy loss of the ions when they pass through a thin carbon foil. This allows us to model analytically the response of the time of flight mass spectrometer to solar wind ions. Thus we present a new version of the analytical response of the solid state detectors to solar wind ions. Various important parameters needed for our models were derived, based on calibration data and on the first flight measurements obtained from STEREO-A. We used information from each measured event that is registered in full resolution in the Pulse Height Analysis words and we derived a new algorithm for the analysis of both existing and future data sets of a similar nature which was tested and works well. This algorithm allows us to obtain, for each measured event, the mass, atomic number and charge state in the correct physical units. Finally, an important criterion was developed for filtering our Fe raw flight data set from the pulse height data without discriminating charge states.

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OBJECTIVES To analyze the prognostic value of clinical tumor response during chemoradiation for locally advanced head and neck cancer. PATIENTS AND METHODS The locoregional response at 50.4Gy was assessed by physical examination (PE) in patients treated within the randomized trial SAKK 10/94 using hyperfractionated radiotherapy (RT), median total dose 74.4Gy with or without cisplatin 20mg/m(2) chemotherapy on 5 consecutive days during weeks 1 and 5 or 6 of RT. Response was classified as a complete response (CR), complete response with uncertainty (Cru), partial response (PR), stable disease (SD), or progressive disease (PD). The primary endpoint was time to treatment failure (TTF) due to any cause. Secondary endpoints included locoregional-recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS) and overall survival (OS). Univariate and multivariate Cox proportional hazards (PH) models were applied to analyze the associations between survival endpoints and clinical tumor response. RESULTS A total of 136, 131 and 97 patients were evaluable for response at the primary tumor, lymph nodes and both sites combined, respectively. At 50.4Gy 57/136 (42%), 46/131 (35%) and 21/97 (22%) patients had a good response (CR/Cru vs. PR/SD) at the primary tumor, the lymph nodes, and both sites combined, respectively. The median follow-up times were 11.4, 9.6 and 11.4years for the three groups. Good responses were all significantly associated with improved TTF, LRRFS, DMFS and OS in univariate analysis whereas good response at the primary tumor and lymph nodes remained significantly associated with TTF and OS after multivariate Cox PH models. CONCLUSIONS Locoregional response at 50.4Gy was identified as predictor of oncologic outcome. PE during treatment should not be underestimated in clinical practice.

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Background: Accelerometry has been established as an objective method that can be used to assess physical activity behavior in large groups. The purpose of the current study was to provide a validated equation to translate accelerometer counts of the triaxial GT3X into energy expenditure in young children. Methods: Thirty-two children aged 5–9 years performed locomotor and play activities that are typical for their age group. Children wore a GT3X accelerometer and their energy expenditure was measured with indirect calorimetry. Twenty-one children were randomly selected to serve as development group. A cubic 2-regression model involving separate equations for locomotor and play activities was developed on the basis of model fit. It was then validated using data of the remaining children and compared with a linear 2-regression model and a linear 1-regression model. Results: All 3 regression models produced strong correlations between predicted and measured MET values. Agreement was acceptable for the cubic model and good for both linear regression approaches. Conclusions: The current linear 1-regression model provides valid estimates of energy expenditure for ActiGraph GT3X data for 5- to 9-year-old children and shows equal or better predictive validity than a cubic or a linear 2-regression model.

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Several methods based on Kriging have recently been proposed for calculating a probability of failure involving costly-to-evaluate functions. A closely related problem is to estimate the set of inputs leading to a response exceeding a given threshold. Now, estimating such a level set—and not solely its volume—and quantifying uncertainties on it are not straightforward. Here we use notions from random set theory to obtain an estimate of the level set, together with a quantification of estimation uncertainty. We give explicit formulae in the Gaussian process set-up and provide a consistency result. We then illustrate how space-filling versus adaptive design strategies may sequentially reduce level set estimation uncertainty.

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In this article, we perform an extensive study of flavor observables in a two-Higgs-doublet model with generic Yukawa structure (of type III). This model is interesting not only because it is the decoupling limit of the minimal supersymmetric standard model but also because of its rich flavor phenomenology which also allows for sizable effects not only in flavor-changing neutral-current (FCNC) processes but also in tauonic B decays. We examine the possible effects in flavor physics and constrain the model both from tree-level processes and from loop observables. The free parameters of the model are the heavy Higgs mass, tanβ (the ratio of vacuum expectation values) and the “nonholomorphic” Yukawa couplings ϵfij(f=u,d,ℓ). In our analysis we constrain the elements ϵfij in various ways: In a first step we give order of magnitude constraints on ϵfij from ’t Hooft’s naturalness criterion, finding that all ϵfij must be rather small unless the third generation is involved. In a second step, we constrain the Yukawa structure of the type-III two-Higgs-doublet model from tree-level FCNC processes (Bs,d→μ+μ−, KL→μ+μ−, D¯¯¯0→μ+μ−, ΔF=2 processes, τ−→μ−μ+μ−, τ−→e−μ+μ− and μ−→e−e+e−) and observe that all flavor off-diagonal elements of these couplings, except ϵu32,31 and ϵu23,13, must be very small in order to satisfy the current experimental bounds. In a third step, we consider Higgs mediated loop contributions to FCNC processes [b→s(d)γ, Bs,d mixing, K−K¯¯¯ mixing and μ→eγ] finding that also ϵu13 and ϵu23 must be very small, while the bounds on ϵu31 and ϵu32 are especially weak. Furthermore, considering the constraints from electric dipole moments we obtain constrains on some parameters ϵu,ℓij. Taking into account the constraints from FCNC processes we study the size of possible effects in the tauonic B decays (B→τν, B→Dτν and B→D∗τν) as well as in D(s)→τν, D(s)→μν, K(π)→eν, K(π)→μν and τ→K(π)ν which are all sensitive to tree-level charged Higgs exchange. Interestingly, the unconstrained ϵu32,31 are just the elements which directly enter the branching ratios for B→τν, B→Dτν and B→D∗τν. We show that they can explain the deviations from the SM predictions in these processes without fine-tuning. Furthermore, B→τν, B→Dτν and B→D∗τν can even be explained simultaneously. Finally, we give upper limits on the branching ratios of the lepton flavor-violating neutral B meson decays (Bs,d→μe, Bs,d→τe and Bs,d→τμ) and correlate the radiative lepton decays (τ→μγ, τ→eγ and μ→eγ) to the corresponding neutral current lepton decays (τ−→μ−μ+μ−, τ−→e−μ+μ− and μ−→e−e+e−). A detailed Appendix contains all relevant information for the considered processes for general scalar-fermion-fermion couplings.

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Dementia caregiving is associated with elevations in depressive symptoms and increased risk for cardiovascular diseases (CVD). This study evaluated the efficacy of the Pleasant Events Program (PEP), a 6-week Behavioral Activation intervention designed to reduce CVD risk and depressive symptoms in caregivers. One hundred dementia family caregivers were randomized to either the 6-week PEP intervention (N = 49) or a time-equivalent Information-Support (IS) control condition (N = 51). Assessments were completed pre- and post-intervention and at 1-year follow-up. Biological assessments included CVD risk markers Interleukin-6 (IL-6) and D-dimer. Psychosocial outcomes included depressive symptoms, positive affect, and negative affect. Participants receiving the PEP intervention had significantly greater reductions in IL-6 (p = .040), depressive symptoms (p = .039), and negative affect (p = .021) from pre- to post-treatment. For IL-6, clinically significant improvement was observed in 20.0% of PEP participants and 6.5% of IS participants. For depressive symptoms, clinically significant improvement was found for 32.7% of PEP vs 11.8% of IS participants. Group differences in change from baseline to 1-year follow-up were non-significant for all outcomes. The PEP program decreased depression and improved a measure of physiological health in older dementia caregivers. Future research should examine the efficacy of PEP for improving other CVD biomarkers and seek to sustain the intervention's effects.

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This study analyses the impact on the oceanic mean state of the evolution of the oceanic component (NEMO) of the climate model developed at Institut Pierre Simon Laplace (IPSL-CM), from the version IPSL-CM4, used for third phase of the Coupled Model Intercomparison Project (CMIP3), to IPSL-CM5A, used for CMIP5. Several modifications have been implemented between these two versions, in particular an interactive coupling with a biogeochemical module, a 3-band model for the penetration of the solar radiation, partial steps at the bottom of the ocean and a set of physical parameterisations to improve the representation of the impact of turbulent and tidal mixing. A set of forced and coupled experiments is used to single out the effect of each of these modifications and more generally the evolution of the oceanic component on the IPSL coupled models family. Major improvements are located in the Southern Ocean, where physical parameterisations such as partial steps and tidal mixing reinforce the barotropic transport of water mass, in particular in the Antarctic Circumpolar Current) and ensure a better representation of Antarctic bottom water masses. However, our analysis highlights that modifications, which substantially improve ocean dynamics in forced configuration, can yield or amplify biases in coupled configuration. In particular, the activation of radiative biophysical coupling between biogeochemical cycle and ocean dynamics results in a cooling of the ocean mean state. This illustrates the difficulty to improve and tune coupled climate models, given the large number of degrees of freedom and the potential compensating effects masking some biases.

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Current models of embryological development focus on intracellular processes such as gene expression and protein networks, rather than on the complex relationship between subcellular processes and the collective cellular organization these processes support. We have explored this collective behavior in the context of neocortical development, by modeling the expansion of a small number of progenitor cells into a laminated cortex with layer and cell type specific projections. The developmental process is steered by a formal language analogous to genomic instructions, and takes place in a physically realistic three-dimensional environment. A common genome inserted into individual cells control their individual behaviors, and thereby gives rise to collective developmental sequences in a biologically plausible manner. The simulation begins with a single progenitor cell containing the artificial genome. This progenitor then gives rise through a lineage of offspring to distinct populations of neuronal precursors that migrate to form the cortical laminae. The precursors differentiate by extending dendrites and axons, which reproduce the experimentally determined branching patterns of a number of different neuronal cell types observed in the cat visual cortex. This result is the first comprehensive demonstration of the principles of self-construction whereby the cortical architecture develops. In addition, our model makes several testable predictions concerning cell migration and branching mechanisms.

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Within the context of exoplanetary atmospheres, we present a comprehensive linear analysis of forced, damped, magnetized shallow water systems, exploring the effects of dimensionality, geometry (Cartesian, pseudo-spherical, and spherical), rotation, magnetic tension, and hydrodynamic and magnetic sources of friction. Across a broad range of conditions, we find that the key governing equation for atmospheres and quantum harmonic oscillators are identical, even when forcing (stellar irradiation), sources of friction (molecular viscosity, Rayleigh drag, and magnetic drag), and magnetic tension are included. The global atmospheric structure is largely controlled by a single key parameter that involves the Rossby and Prandtl numbers. This near-universality breaks down when either molecular viscosity or magnetic drag acts non-uniformly across latitude or a poloidal magnetic field is present, suggesting that these effects will introduce qualitative changes to the familiar chevron-shaped feature witnessed in simulations of atmospheric circulation. We also find that hydrodynamic and magnetic sources of friction have dissimilar phase signatures and affect the flow in fundamentally different ways, implying that using Rayleigh drag to mimic magnetic drag is inaccurate. We exhaustively lay down the theoretical formalism (dispersion relations, governing equations, and time-dependent wave solutions) for a broad suite of models. In all situations, we derive the steady state of an atmosphere, which is relevant to interpreting infrared phase and eclipse maps of exoplanetary atmospheres. We elucidate a pinching effect that confines the atmospheric structure to be near the equator. Our suite of analytical models may be used to develop decisively physical intuition and as a reference point for three-dimensional magnetohydrodynamic simulations of atmospheric circulation.

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Objective We evaluated whether regional differences in physical activity (PA) and sedentary behaviour (SB) existed along language boundaries within Switzerland and whether potential differences would be explained by socio-demographics or environmental characteristics. Methods We combined data of 611 children aged 4 to 7 years from four regional studies. PA and SB were assessed by accelerometers. Information about the socio-demographic background was obtained by questionnaires. Objective neighbourhood attributes could be linked to home addresses. Multivariate regression models were used to test associations between PA and SB and socio-demographic characteristics and neighbourhood attributes. Results Children from the German compared to the French-speaking region were more physically active and less sedentary (by 10–15 %, p < 0.01). Although German-speaking children lived in a more favourable environment and a higher socioeconomic neighbourhood (differences p < 0.001), these characteristics did not explain the differences in PA behaviour between French and German speaking. Conclusions Factors related to the language region, which might be culturally rooted were among the strongest correlates of PA and SB among Swiss children, independent of individual, social and environmental factors.

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Background: Health behavior change models identify effective self-regulatory skills for behavioral change, but the social context is usually neglected. This study investigated the effectiveness of a dyadic conceptualization of action control for promoting physical activity. Methods: 121 overweight individuals and their partners were randomly allocated to one of two experimental (dyadic vs. individual action control) and two control conditions. Participants completed questionnaires at baseline (T1) and four weeks later (T2) including measures of action control and 7-day recall physical activity. Findings: Results showed that action control signi+cantly increased from T1 to T2 and was overall higher in the experimental conditions compared to control conditions. In terms of physical activity, no overall intervention effect emerged. However, post hoc analyses revealed higher mean levels of sport activities in the dyadic intervention group compared to all other groups. Discussion: Overall, +ndings provide +rst support for the usefulness of a dyadic action control intervention, and suggest further investigation of objective measures of physical activity and secondary outcomes

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Snow in the environment acts as a host to rich chemistry and provides a matrix for physical exchange of contaminants within the ecosystem. The goal of this review is to summarise the current state of knowledge of physical processes and chemical reactivity in surface snow with relevance to polar regions. It focuses on a description of impurities in distinct compartments present in surface snow, such as snow crystals, grain boundaries, crystal surfaces, and liquid parts. It emphasises the microscopic description of the ice surface and its link with the environment. Distinct differences between the disordered air–ice interface, often termed quasi-liquid layer, and a liquid phase are highlighted. The reactivity in these different compartments of surface snow is discussed using many experimental studies, simulations, and selected snow models from the molecular to the macro-scale. Although new experimental techniques have extended our knowledge of the surface properties of ice and their impact on some single reactions and processes, others occurring on, at or within snow grains remain unquantified. The presence of liquid or liquid-like compartments either due to the formation of brine or disorder at surfaces of snow crystals below the freezing point may strongly modify reaction rates. Therefore, future experiments should include a detailed characterisation of the surface properties of the ice matrices. A further point that remains largely unresolved is the distribution of impurities between the different domains of the condensed phase inside the snowpack, i.e. in the bulk solid, in liquid at the surface or trapped in confined pockets within or between grains, or at the surface. While surface-sensitive laboratory techniques may in the future help to resolve this point for equilibrium conditions, additional uncertainty for the environmental snowpack may be caused by the highly dynamic nature of the snowpack due to the fast metamorphism occurring under certain environmental conditions. Due to these gaps in knowledge the first snow chemistry models have attempted to reproduce certain processes like the long-term incorporation of volatile compounds in snow and firn or the release of reactive species from the snowpack. Although so far none of the models offers a coupled approach of physical and chemical processes or a detailed representation of the different compartments, they have successfully been used to reproduce some field experiments. A fully coupled snow chemistry and physics model remains to be developed.

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AIMS To estimate physical activity trajectories for people who quit smoking, and compare them to what would have been expected had smoking continued. DESIGN, SETTING AND PARTICIPANTS A total of 5115 participants in the Coronary Artery Risk Development in Young Adults Study (CARDIA) study, a population-based study of African American and European American people recruited at age 18-30 years in 1985/6 and followed over 25 years. MEASUREMENTS Physical activity was self-reported during clinical examinations at baseline (1985/6) and at years 2, 5, 7, 10, 15, 20 and 25 (2010/11); smoking status was reported each year (at examinations or by telephone, and imputed where missing). We used mixed linear models to estimate trajectories of physical activity under varying smoking conditions, with adjustment for participant characteristics and secular trends. FINDINGS We found significant interactions by race/sex (P = 0.02 for the interaction with cumulative years of smoking), hence we investigated the subgroups separately. Increasing years of smoking were associated with a decline in physical activity in black and white women and black men [e.g. coefficient for 10 years of smoking: -0.14; 95% confidence interval (CI) = -0.20 to -0.07, P < 0.001 for white women]. An increase in physical activity was associated with years since smoking cessation in white men (coefficient 0.06; 95% CI = 0 to 0.13, P = 0.05). The physical activity trajectory for people who quit diverged progressively towards higher physical activity from the expected trajectory had smoking continued. For example, physical activity was 34% higher (95% CI = 18 to 52%; P < 0.001) for white women 10 years after stopping compared with continuing smoking for those 10 years (P = 0.21 for race/sex differences). CONCLUSIONS Smokers who quit have progressively higher levels of physical activity in the years after quitting compared with continuing smokers.

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The challenge for sustainable organic dairy farming is identification of cows that are well adapted to forage-based production systems. Therefore, the aim of this study was to compare the grazing behaviour, physical activity and metabolic profile of two different Holstein strains kept in an organic grazing system without concentrate supplementation. Twelve Swiss (HCH ; 566 kg body weight (BW) and 12 New Zealand Holstein-Friesian (HNZ ; 530 kg BW) cows in mid-lactation were kept in a rotational grazing system. After an adaptation period, the milk yield, nutrient intake, physical activity and grazing behaviour were recorded for each cow for 7 days. On three consecutive days, blood was sampled at 07:00, 12:00 and 17:00 h from each cow by jugular vein puncture. Data were analysed using linear mixed models. No differences were found in milk yield, but milk fat (3.69 vs. 4.05%, P = 0.05) and milk protein percentage (2.92 vs. 3.20%, P < 0.01) were lower in HCH than in HNZ cows. Herbage intake did not differ between strains, but organic matter digestibility was greater (P = 0.01) in HCH compared to HNZ cows. The HCH cows spent less (P = 0.04) time ruminating (439 vs. 469 min/day) and had a lower (P = 0.02) number of ruminating boli when compared to the HNZ cows. The time spent eating and physical activity did not differ between strains. Concentrations of IGF-1 and T3 were lower (P ≤ 0.05) in HCH than HNZ cows. In conclusion, HCH cows were not able to increase dry matter intake in order to express their full genetic potential for milk production when kept in an organic grazing system without concentrate supplementation. On the other hand, HNZ cows seem to compensate for the reduced nutrient availability better than HCH cows but could not use that advantage for increased production efficiency