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Sample records for subgrid scale stresses

  1. Simple subgrid scale stresses models for homogeneous isotropic turbulence

    Science.gov (United States)

    Aupoix, B.; Cousteix, J.

    Large eddy simulations employing the filtering of Navier-Stokes equations highlight stresses, related to the interaction between large scales below the cut and small scales above it, which have been designated 'subgrid scale stresses'. Their effects include both the energy flux through the cut and a component of viscous diffusion. The eddy viscosity introduced in the subgrid scale models which give the correct energy flux through the cut by comparison with spectral closures is shown to depend only on the small scales. The Smagorinsky (1963) model can only be obtained if the cut lies in the middle of the inertial range. A novel model which takes the small scales into account statistically, and includes the effects of viscosity, is proposed and compared with classical models for the Comte-Bellot and Corrsin (1971) experiment.

  2. Subgrid-scale stresses and scalar fluxes constructed by the multi-scale turnover Lagrangian map

    Science.gov (United States)

    AL-Bairmani, Sukaina; Li, Yi; Rosales, Carlos; Xie, Zheng-tong

    2017-04-01

    The multi-scale turnover Lagrangian map (MTLM) [C. Rosales and C. Meneveau, "Anomalous scaling and intermittency in three-dimensional synthetic turbulence," Phys. Rev. E 78, 016313 (2008)] uses nested multi-scale Lagrangian advection of fluid particles to distort a Gaussian velocity field and, as a result, generate non-Gaussian synthetic velocity fields. Passive scalar fields can be generated with the procedure when the fluid particles carry a scalar property [C. Rosales, "Synthetic three-dimensional turbulent passive scalar fields via the minimal Lagrangian map," Phys. Fluids 23, 075106 (2011)]. The synthetic fields have been shown to possess highly realistic statistics characterizing small scale intermittency, geometrical structures, and vortex dynamics. In this paper, we present a study of the synthetic fields using the filtering approach. This approach, which has not been pursued so far, provides insights on the potential applications of the synthetic fields in large eddy simulations and subgrid-scale (SGS) modelling. The MTLM method is first generalized to model scalar fields produced by an imposed linear mean profile. We then calculate the subgrid-scale stress, SGS scalar flux, SGS scalar variance, as well as related quantities from the synthetic fields. Comparison with direct numerical simulations (DNSs) shows that the synthetic fields reproduce the probability distributions of the SGS energy and scalar dissipation rather well. Related geometrical statistics also display close agreement with DNS results. The synthetic fields slightly under-estimate the mean SGS energy dissipation and slightly over-predict the mean SGS scalar variance dissipation. In general, the synthetic fields tend to slightly under-estimate the probability of large fluctuations for most quantities we have examined. Small scale anisotropy in the scalar field originated from the imposed mean gradient is captured. The sensitivity of the synthetic fields on the input spectra is assessed by

  3. Exploring the Limits of the Dynamic Procedure for Modeling Subgrid-Scale Stresses in LES of Inhomogeneous Flows.

    Science.gov (United States)

    Le, A.-T.; Kim, J.; Coleman, G.

    1996-11-01

    One of the primary reasons dynamic subgrid-scale (SGS) models are more successful than those that are `hand-tuned' is thought to be their insensitivity to numerical and modeling parameters. Jiménez has recently demonstrated that large-eddy simulations (LES) of decaying isotropic turbulence using a dynamic Smagorinsky model yield correct decay rates -- even when the model is subjected to a range of artificial perturbations. The objective of the present study is to determine to what extent this `self-adjusting' feature of dynamic SGS models is found in LES of inhomogeneous flows. The effects of numerical and modeling parameters on the accuracy of LES solutions of fully developed and developing turbulent channel flow are studied, using a spectral code and various dynamic models (including those of Lilly et al. and Meneveau et al.); other modeling parameters tested include the filter-width ratio and the effective magnitude of the Smagorinsky coefficient. Numerical parameters include the form of the convective term and the type of test filter (sharp-cutoff versus tophat). The resulting LES statistics are found to be surprisingly sensitive to the various parameter choices, which implies that more care than is needed for homogeneous-flow simulations must be exercised when performing LES of inhomogeneous flows.

  4. A priori study of subgrid-scale flux of a passive scalar in isotropic homogeneous turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Chumakov, Sergei [Los Alamos National Laboratory

    2008-01-01

    We perform a direct numerical simulation (DNS) of forced homogeneous isotropic turbulence with a passive scalar that is forced by mean gradient. The DNS data are used to study the properties of subgrid-scale flux of a passive scalar in the framework of large eddy simulation (LES), such as alignment trends between the flux, resolved, and subgrid-scale flow structures. It is shown that the direction of the flux is strongly coupled with the subgrid-scale stress axes rather than the resolved flow quantities such as strain, vorticity, or scalar gradient. We derive an approximate transport equation for the subgrid-scale flux of a scalar and look at the relative importance of the terms in the transport equation. A particular form of LES tensor-viscosity model for the scalar flux is investigated, which includes the subgrid-scale stress. Effect of different models for the subgrid-scale stress on the model for the subgrid-scale flux is studied.

  5. Sub-Grid Scale Plume Modeling

    Directory of Open Access Journals (Sweden)

    Greg Yarwood

    2011-08-01

    Full Text Available Multi-pollutant chemical transport models (CTMs are being routinely used to predict the impacts of emission controls on the concentrations and deposition of primary and secondary pollutants. While these models have a fairly comprehensive treatment of the governing atmospheric processes, they are unable to correctly represent processes that occur at very fine scales, such as the near-source transport and chemistry of emissions from elevated point sources, because of their relatively coarse horizontal resolution. Several different approaches have been used to address this limitation, such as using fine grids, adaptive grids, hybrid modeling, or an embedded sub-grid scale plume model, i.e., plume-in-grid (PinG modeling. In this paper, we first discuss the relative merits of these various approaches used to resolve sub-grid scale effects in grid models, and then focus on PinG modeling which has been very effective in addressing the problems listed above. We start with a history and review of PinG modeling from its initial applications for ozone modeling in the Urban Airshed Model (UAM in the early 1980s using a relatively simple plume model, to more sophisticated and state-of-the-science plume models, that include a full treatment of gas-phase, aerosol, and cloud chemistry, embedded in contemporary models such as CMAQ, CAMx, and WRF-Chem. We present examples of some typical results from PinG modeling for a variety of applications, discuss the implications of PinG on model predictions of source attribution, and discuss possible future developments and applications for PinG modeling.

  6. Physical consistency of subgrid-scale models for large-eddy simulation of incompressible turbulent flows

    CERN Document Server

    Silvis, Maurits H; Verstappen, Roel

    2016-01-01

    We study the construction of subgrid-scale models for large-eddy simulation of incompressible turbulent flows. In particular, we aim to consolidate a systematic approach of constructing subgrid-scale models, based on the idea that it is desirable that subgrid-scale models are consistent with the properties of the Navier-Stokes equations and the turbulent stresses. To that end, we first discuss in detail the symmetries of the Navier-Stokes equations, and the near-wall scaling behavior, realizability and dissipation properties of the turbulent stresses. We furthermore summarize the requirements that subgrid-scale models have to satisfy in order to preserve these important mathematical and physical properties. In this fashion, a framework of model constraints arises that we apply to analyze the behavior of a number of existing subgrid-scale models that are based on the local velocity gradient. We show that these subgrid-scale models do not satisfy all the desired properties, after which we explain that this is p...

  7. Subgrid-scale turbulence in shock-boundary layer flows

    Science.gov (United States)

    Jammalamadaka, Avinash; Jaberi, Farhad

    2015-04-01

    Data generated by direct numerical simulation (DNS) for a Mach 2.75 zero-pressure gradient turbulent boundary layer interacting with shocks of different intensities are used for a priori analysis of subgrid-scale (SGS) turbulence and various terms in the compressible filtered Navier-Stokes equations. The numerical method used for DNS is based on a hybrid scheme that uses a non-dissipative central scheme in the shock-free turbulent regions and a robust monotonicity-preserving scheme in the shock regions. The behavior of SGS stresses and their components, namely Leonard, Cross and Reynolds components, is examined in various regions of the flow for different shock intensities and filter widths. The backscatter in various regions of the flow is found to be significant only instantaneously, while the ensemble-averaged statistics indicate no significant backscatter. The budgets for the SGS kinetic energy equation are examined for a better understanding of shock-tubulence interactions at the subgrid level and also with the aim of providing useful information for one-equation LES models. A term-by-term analysis of SGS terms in the filtered total energy equation indicate that while each term in this equation is significant by itself, the net contribution by all of them is relatively small. This observation is consistent with our a posteriori analysis.

  8. Statistical dynamical subgrid-scale parameterizations for geophysical flows

    Energy Technology Data Exchange (ETDEWEB)

    O' Kane, T J; Frederiksen, J S [Centre for Australian Weather and Climate Research, Bureau of Meteorology, 700 Collins St, Docklands, Melbourne, VIC (Australia) and CSIRO Marine and Atmospheric Research, Aspendale, VIC (Australia)], E-mail: t.okane@bom.gov.au

    2008-12-15

    Simulations of both atmospheric and oceanic circulations at given finite resolutions are strongly dependent on the form and strengths of the dynamical subgrid-scale parameterizations (SSPs) and in particular are sensitive to subgrid-scale transient eddies interacting with the retained scale topography and the mean flow. In this paper, we present numerical results for SSPs of the eddy-topographic force, stochastic backscatter, eddy viscosity and eddy-mean field interaction using an inhomogeneous statistical turbulence model based on a quasi-diagonal direct interaction approximation (QDIA). Although the theoretical description on which our model is based is for general barotropic flows, we specifically focus on global atmospheric flows where large-scale Rossby waves are present. We compare and contrast the closure-based results with an important earlier heuristic SSP of the eddy-topographic force, based on maximum entropy or statistical canonical equilibrium arguments, developed specifically for general ocean circulation models (Holloway 1992 J. Phys. Oceanogr. 22 1033-46). Our results demonstrate that where strong zonal flows and Rossby waves are present, such as in the atmosphere, maximum entropy arguments are insufficient to accurately parameterize the subgrid contributions due to eddy-eddy, eddy-topographic and eddy-mean field interactions. We contrast our atmospheric results with findings for the oceans. Our study identifies subgrid-scale interactions that are currently not parameterized in numerical atmospheric climate models, which may lead to systematic defects in the simulated circulations.

  9. Subgrid-scale models for large-eddy simulation of rotating turbulent channel flows

    Science.gov (United States)

    Silvis, Maurits H.; Bae, Hyunji Jane; Trias, F. Xavier; Abkar, Mahdi; Moin, Parviz; Verstappen, Roel

    2017-11-01

    We aim to design subgrid-scale models for large-eddy simulation of rotating turbulent flows. Rotating turbulent flows form a challenging test case for large-eddy simulation due to the presence of the Coriolis force. The Coriolis force conserves the total kinetic energy while transporting it from small to large scales of motion, leading to the formation of large-scale anisotropic flow structures. The Coriolis force may also cause partial flow laminarization and the occurrence of turbulent bursts. Many subgrid-scale models for large-eddy simulation are, however, primarily designed to parametrize the dissipative nature of turbulent flows, ignoring the specific characteristics of transport processes. We, therefore, propose a new subgrid-scale model that, in addition to the usual dissipative eddy viscosity term, contains a nondissipative nonlinear model term designed to capture transport processes, such as those due to rotation. We show that the addition of this nonlinear model term leads to improved predictions of the energy spectra of rotating homogeneous isotropic turbulence as well as of the Reynolds stress anisotropy in spanwise-rotating plane-channel flows. This work is financed by the Netherlands Organisation for Scientific Research (NWO) under Project Number 613.001.212.

  10. Importance of subgrid-scale parameterization in numerical simulations of lake circulation

    Science.gov (United States)

    Wang, Yongqi

    Two subgrid-scale modeling techniques--Smagorinsky's postulation for the horizontal eddy viscosity and the Mellor-Yamada level-2 model for the vertical eddy viscosity--are applied as turbulence closure conditions to numerical simulations of resolved-scale baroclinic lake circulations. The use of the total variation diminishing (TVD) technique in the numerical treatment of the advection terms in the governing equations depresses numerical diffusion to an acceptably low level and makes stable numerical performances possible with small eddy viscosities resulting from the turbulence closure parameterizations. The results show that, with regard to the effect of an external wind stress, the vertical turbulent mixing is mainly restricted to the topmost epilimnion with the order of magnitude for the vertical eddy viscosity of 10 -3 m 2 s -1, whilst the horizontal turbulent mixing may reach a somewhat deeper zone with an order of magnitude for the horizontal eddy viscosity of 0.1-1 m 2 s -1. Their spatial and temporal variations and influences on numerical results are significant. A comparison with prescribed constant eddy viscosities clearly shows the importance of subgrid-scale closures on resolved-scale flows in the lake circulation simulation. A predetermination of the eddy viscosities is inappropriate and should be abandoned. Their values must be determined by suitable subgrid-scale closure techniques.

  11. Modeling Subgrid Scale Droplet Deposition in Multiphase-CFD

    Science.gov (United States)

    Agostinelli, Giulia; Baglietto, Emilio

    2017-11-01

    The development of first-principle-based constitutive equations for the Eulerian-Eulerian CFD modeling of annular flow is a major priority to extend the applicability of multiphase CFD (M-CFD) across all two-phase flow regimes. Two key mechanisms need to be incorporated in the M-CFD framework, the entrainment of droplets from the liquid film, and their deposition. Here we focus first on the aspect of deposition leveraging a separate effects approach. Current two-field methods in M-CFD do not include appropriate local closures to describe the deposition of droplets in annular flow conditions. As many integral correlations for deposition have been proposed for lumped parameters methods applications, few attempts exist in literature to extend their applicability to CFD simulations. The integral nature of the approach limits its applicability to fully developed flow conditions, without geometrical or flow variations, therefore negating the scope of CFD application. A new approach is proposed here that leverages local quantities to predict the subgrid-scale deposition rate. The methodology is first tested into a three-field approach CFD model.

  12. Exploring nonlinear subgrid-scale models and new characteristic length scales for large-eddy simulation

    NARCIS (Netherlands)

    Silvis, Maurits H.; Trias, F. Xavier; Abkar, M.; Bae, H.J.; Lozano-Duran, A.; Verstappen, R.W.C.P.; Moin, Parviz; Urzay, Javier

    2016-01-01

    We study subgrid-scale modeling for large-eddy simulation of anisotropic turbulent flows on anisotropic grids. In particular, we show how the addition of a velocity-gradient-based nonlinear model term to an eddy viscosity model provides a better representation of energy transfer. This is shown to

  13. Evapotranspiration and cloud variability at regional sub-grid scales

    Science.gov (United States)

    Vila-Guerau de Arellano, Jordi; Sikma, Martin; Pedruzo-Bagazgoitia, Xabier; van Heerwaarden, Chiel; Hartogensis, Oscar; Ouwersloot, Huug

    2017-04-01

    In regional and global models uncertainties arise due to our incomplete understanding of the coupling between biochemical and physical processes. Representing their impact depends on our ability to calculate these processes using physically sound parameterizations, since they are unresolved at scales smaller than the grid size. More specifically over land, the coupling between evapotranspiration, turbulent transport of heat and moisture, and clouds lacks a combined representation to take these sub-grid scales interactions into account. Our approach is based on understanding how radiation, surface exchange, turbulent transport and moist convection are interacting from the leaf- to the cloud scale. We therefore place special emphasis on plant stomatal aperture as the main regulator of CO2-assimilation and water transpiration, a key source of moisture source to the atmosphere. Plant functionality is critically modulated by interactions with atmospheric conditions occurring at very short spatiotemporal scales such as cloud radiation perturbations or water vapour turbulent fluctuations. By explicitly resolving these processes, the LES (large-eddy simulation) technique is enabling us to characterize and better understand the interactions between canopies and the local atmosphere. This includes the adaption time of vegetation to rapid changes in atmospheric conditions driven by turbulence or the presence of cumulus clouds. Our LES experiments are based on explicitly coupling the diurnal atmospheric dynamics to a plant physiology model. Our general hypothesis is that different partitioning of direct and diffuse radiation leads to different responses of the vegetation. As a result there are changes in the water use efficiencies and shifts in the partitioning of sensible and latent heat fluxes under the presence of clouds. Our presentation is as follows. First, we discuss the ability of LES to reproduce the surface energy balance including photosynthesis and CO2 soil

  14. The subgrid-scale scalar variance under supercritical pressure conditions

    Science.gov (United States)

    Masi, Enrica; Bellan, Josette

    2011-08-01

    To model the subgrid-scale (SGS) scalar variance under supercritical-pressure conditions, an equation is first derived for it. This equation is considerably more complex than its equivalent for atmospheric-pressure conditions. Using a previously created direct numerical simulation (DNS) database of transitional states obtained for binary-species systems in the context of temporal mixing layers, the activity of terms in this equation is evaluated, and it is found that some of these new terms have magnitude comparable to that of governing terms in the classical equation. Most prominent among these new terms are those expressing the variation of diffusivity with thermodynamic variables and Soret terms having dissipative effects. Since models are not available for these new terms that would enable solving the SGS scalar variance equation, the adopted strategy is to directly model the SGS scalar variance. Two models are investigated for this quantity, both developed in the context of compressible flows. The first one is based on an approximate deconvolution approach and the second one is a gradient-like model which relies on a dynamic procedure using the Leonard term expansion. Both models are successful in reproducing the SGS scalar variance extracted from the filtered DNS database, and moreover, when used in the framework of a probability density function (PDF) approach in conjunction with the β-PDF, they excellently reproduce a filtered quantity which is a function of the scalar. For the dynamic model, the proportionality coefficient spans a small range of values through the layer cross-stream coordinate, boding well for the stability of large eddy simulations using this model.

  15. Multifractal subgrid-scale modeling within a variational multiscale method for large-eddy simulation of turbulent flow

    Science.gov (United States)

    Rasthofer, U.; Gravemeier, V.

    2013-02-01

    Multifractal subgrid-scale modeling within a variational multiscale method is proposed for large-eddy simulation of turbulent flow. In the multifractal subgrid-scale modeling approach, the subgrid-scale velocity is evaluated from a multifractal description of the subgrid-scale vorticity, which is based on the multifractal scale similarity of gradient fields in turbulent flow. The multifractal subgrid-scale modeling approach is integrated into a variational multiscale formulation, which constitutes a new application of the variational multiscale concept. A focus of this study is on the application of the multifractal subgrid-scale modeling approach to wall-bounded turbulent flow. Therefore, a near-wall limit of the multifractal subgrid-scale modeling approach is derived in this work. The novel computational approach of multifractal subgrid-scale modeling within a variational multiscale formulation is applied to turbulent channel flow at various Reynolds numbers, turbulent flow over a backward-facing step and turbulent flow past a square-section cylinder, which are three of the most important and widely-used benchmark examples for wall-bounded turbulent flow. All results presented in this study confirm a very good performance of the proposed method. Compared to a dynamic Smagorinsky model and a residual-based variational multiscale method, improved results are obtained. Moreover, it is demonstrated that the subgrid-scale energy transfer incorporated by the proposed method very well approximates the expected energy transfer as obtained from appropriately filtered direct numerical simulation data. The computational cost is notably reduced compared to a dynamic Smagorinsky model and only marginally increased compared to a residual-based variational multiscale method.

  16. Lagrangian scheme to model subgrid-scale mixing and spreading in heterogeneous porous media

    Science.gov (United States)

    Herrera, P. A.; Cortínez, J. M.; Valocchi, A. J.

    2017-04-01

    Small-scale heterogeneity of permeability controls spreading, dilution, and mixing of solute plumes at large scale. However, conventional numerical simulations of solute transport are unable to resolve scales of heterogeneity below the grid scale. We propose a Lagrangian numerical approach to implement closure models to account for subgrid-scale spreading and mixing in Darcy-scale numerical simulations of solute transport in mildly heterogeneous porous media. The novelty of the proposed approach is that it considers two different dispersion coefficients to account for advective spreading mechanisms and local-scale dispersion. Using results of benchmark numerical simulations, we demonstrate that the proposed approach is able to model subgrid-scale spreading and mixing provided there is a correct choice of block-scale dispersion coefficient. We also demonstrate that for short travel times it is only possible to account for spreading or mixing using a single block-scale dispersion coefficient. Moreover, we show that it is necessary to use time-dependent dispersion coefficients to obtain correct mixing rates. On the contrary, for travel times that are large in comparison to the typical dispersive time scale, it is possible to use a single expression to compute the block-dispersion coefficient, which is equal to the asymptotic limit of the block-scale macrodispersion coefficient proposed by Rubin et al. (1999). Our approach provides a flexible and efficient way to model subgrid-scale mixing in numerical models of large-scale solute transport in heterogeneous aquifers. We expect that these findings will help to better understand the applicability of the advection-dispersion-equation (ADE) to simulate solute transport at the Darcy scale in heterogeneous porous media.

  17. Stochastic fields method for sub-grid scale emission heterogeneity in mesoscale atmospheric dispersion models

    OpenAIRE

    M. Cassiani; Vinuesa, J.F.; Galmarini, S.; Denby, B

    2010-01-01

    The stochastic fields method for turbulent reacting flows has been applied to the issue of sub-grid scale emission heterogeneity in a mesoscale model. This method is a solution technique for the probability density function (PDF) transport equation and can be seen as a straightforward extension of currently used mesoscale dispersion models. It has been implemented in an existing mesoscale model and the results are compared with Large-Eddy Simulation (LES) data devised to test specifically the...

  18. Stochastic fields method for sub-grid scale emission heterogeneity in mesoscale atmospheric dispersion models

    Directory of Open Access Journals (Sweden)

    M. Cassiani

    2010-01-01

    Full Text Available The stochastic fields method for turbulent reacting flows has been applied to the issue of sub-grid scale emission heterogeneity in a mesoscale model. This method is a solution technique for the probability density function (PDF transport equation and can be seen as a straightforward extension of currently used mesoscale dispersion models. It has been implemented in an existing mesoscale model and the results are compared with Large-Eddy Simulation (LES data devised to test specifically the effect of sub-grid scale emission heterogeneity on boundary layer concentration fluctuations. The sub-grid scale emission variability is assimilated in the model as a PDF of the emissions. The stochastic fields method shows excellent agreement with the LES data without adjustment of the constants used in the mesoscale model. The stochastic fields method is a stochastic solution of the transport equations for the concentration PDF of dispersing scalars, therefore it possesses the ability to handle chemistry of any complexity without the need to introduce additional closures for the high order statistics of chemical species. This study shows for the first time the feasibility of applying this method to mesoscale chemical transport models.

  19. A priori study of subgrid-scale features in turbulent Rayleigh-Bénard convection

    Science.gov (United States)

    Dabbagh, F.; Trias, F. X.; Gorobets, A.; Oliva, A.

    2017-10-01

    At the crossroad between flow topology analysis and turbulence modeling, a priori studies are a reliable tool to understand the underlying physics of the subgrid-scale (SGS) motions in turbulent flows. In this paper, properties of the SGS features in the framework of a large-eddy simulation are studied for a turbulent Rayleigh-Bénard convection (RBC). To do so, data from direct numerical simulation (DNS) of a turbulent air-filled RBC in a rectangular cavity of aspect ratio unity and π spanwise open-ended distance are used at two Rayleigh numbers R a ∈{1 08,1 010 } [Dabbagh et al., "On the evolution of flow topology in turbulent Rayleigh-Bénard convection," Phys. Fluids 28, 115105 (2016)]. First, DNS at Ra = 108 is used to assess the performance of eddy-viscosity models such as QR, Wall-Adapting Local Eddy-viscosity (WALE), and the recent S3PQR-models proposed by Trias et al. ["Building proper invariants for eddy-viscosity subgrid-scale models," Phys. Fluids 27, 065103 (2015)]. The outcomes imply that the eddy-viscosity modeling smoothes the coarse-grained viscous straining and retrieves fairly well the effect of the kinetic unfiltered scales in order to reproduce the coherent large scales. However, these models fail to approach the exact evolution of the SGS heat flux and are incapable to reproduce well the further dominant rotational enstrophy pertaining to the buoyant production. Afterwards, the key ingredients of eddy-viscosity, νt, and eddy-diffusivity, κt, are calculated a priori and revealed positive prevalent values to maintain a turbulent wind essentially driven by the mean buoyant force at the sidewalls. The topological analysis suggests that the effective turbulent diffusion paradigm and the hypothesis of a constant turbulent Prandtl number are only applicable in the large-scale strain-dominated areas in the bulk. It is shown that the bulk-dominated rotational structures of vortex-stretching (and its synchronous viscous dissipative structures) hold

  20. Evaluation of Subgrid-Scale Transport of Hydrometeors in a PDF-based Scheme using High-Resolution CRM Simulations

    Science.gov (United States)

    Wong, M.; Ovchinnikov, M.; Wang, M.; Larson, V. E.

    2014-12-01

    In current climate models, the model resolution is too coarse to explicitly resolve deep convective systems. Parameterization schemes are therefore needed to represent the physical processes at the sub-grid scale. Recently, an approach based on assumed probability density functions (PDFs) has been developed to help unify the various parameterization schemes used in current global models. In particular, a unified parameterization scheme called the Cloud Layers Unified By Binormals (CLUBB) scheme has been developed and tested successfully for shallow boundary-layer clouds. CLUBB's implementation in the Community Atmosphere Model, version 5 (CAM5) is also being extended to treat deep convection cases, but parameterizing subgrid-scale vertical transport of hydrometeors remains a challenge. To investigate the roots of the problem and possible solutions, we generate a high-resolution benchmark simulation of a deep convection case using a cloud-resolving model (CRM) called System for Atmospheric Modeling (SAM). We use the high-resolution 3D CRM results to assess the prognostic and diagnostic higher-order moments in CLUBB that are in relation to the subgrid-scale transport of hydrometeors. We also analyze the heat and moisture budgets in terms of CLUBB variables from the SAM benchmark simulation. The results from this study will be used to devise a better representation of vertical subgrid-scale transport of hydrometeors by utilizing the sub-grid variability information from CLUBB.

  1. Effects of Implementing Subgrid-Scale Cloud-Radiation Interactions in a Regional Climate Model

    Science.gov (United States)

    Herwehe, J. A.; Alapaty, K.; Otte, T.; Nolte, C. G.

    2012-12-01

    Interactions between atmospheric radiation, clouds, and aerosols are the most important processes that determine the climate and its variability. In regional scale models, when used at relatively coarse spatial resolutions (e.g., larger than 1 km), convective cumulus clouds need to be parameterized as subgrid-scale clouds. Like many groups, our regional climate modeling group at the EPA uses the Weather Research & Forecasting model (WRF) as a regional climate model (RCM). One of the findings from our RCM studies is that the summertime convective systems simulated by the WRF model are highly energetic, leading to excessive surface precipitation. We also found that the WRF model does not consider the interactions between convective clouds and radiation, thereby omitting an important process that drives the climate. Thus, the subgrid-scale cloudiness associated with convective clouds (from shallow cumuli to thunderstorms) does not exist and radiation passes through the atmosphere nearly unimpeded, potentially leading to overly energetic convection. This also has implications for air quality modeling systems that are dependent upon cloud properties from the WRF model, as the failure to account for subgrid-scale cloudiness can lead to problems such as the underrepresentation of aqueous chemistry processes within clouds and the overprediction of ozone from overactive photolysis. In an effort to advance the climate science of the cloud-aerosol-radiation (CAR) interactions in RCM systems, as a first step we have focused on linking the cumulus clouds with the radiation processes. To this end, our research group has implemented into WRF's Kain-Fritsch (KF) cumulus parameterization a cloudiness formulation that is widely used in global earth system models (e.g., CESM/CAM5). Estimated grid-scale cloudiness and associated condensate are adjusted to account for the subgrid clouds and then passed to WRF's Rapid Radiative Transfer Model - Global (RRTMG) radiation schemes to affect

  2. Improving sub-grid scale accuracy of boundary features in regional finite-difference models

    Science.gov (United States)

    Panday, Sorab; Langevin, Christian D.

    2012-01-01

    As an alternative to grid refinement, the concept of a ghost node, which was developed for nested grid applications, has been extended towards improving sub-grid scale accuracy of flow to conduits, wells, rivers or other boundary features that interact with a finite-difference groundwater flow model. The formulation is presented for correcting the regular finite-difference groundwater flow equations for confined and unconfined cases, with or without Newton Raphson linearization of the nonlinearities, to include the Ghost Node Correction (GNC) for location displacement. The correction may be applied on the right-hand side vector for a symmetric finite-difference Picard implementation, or on the left-hand side matrix for an implicit but asymmetric implementation. The finite-difference matrix connectivity structure may be maintained for an implicit implementation by only selecting contributing nodes that are a part of the finite-difference connectivity. Proof of concept example problems are provided to demonstrate the improved accuracy that may be achieved through sub-grid scale corrections using the GNC schemes.

  3. Large eddy simulation of flow over a wall-mounted cube: Comparison of different semi dynamic subgrid scale models

    Directory of Open Access Journals (Sweden)

    M Nooroullahi

    2016-09-01

    Full Text Available In this paper the ability of different semi dynamic subgrid scale models for large eddy simulation was studied in a challenging test case. The semi dynamic subgrid scale models were examined in this investigation is Selective Structure model, Coherent structure model, Wall Adaptive Large Eddy model. The test case is a simulation of flow over a wall-mounted cube in a channel. The results of these models were compared to structure function model, dynamic models and experimental data at Reynolds number 40000. Results show that these semi dynamic models could improve the ability of numerical simulation in comparison with other models which use a constant coefficient for simulation of subgrid scale viscosity. In addition, these models don't have the instability problems of dynamic models.

  4. Parameterization of subgrid plume dilution for use in large-scale atmospheric simulations

    Directory of Open Access Journals (Sweden)

    A. D. Naiman

    2010-03-01

    Full Text Available A new model of plume dynamics has been developed for use as a subgrid model of plume dilution in a large-scale atmospheric simulation. The model uses mean wind, shear, and diffusion parameters derived from the local large-scale variables to advance the plume cross-sectional shape and area in time. Comparisons with a large eddy simulation of aircraft emission plume dynamics, with an analytical solution to the dynamics of a sheared Gaussian plume, and with measurements of aircraft exhaust plume dilution at cruise altitude show good agreement with these previous studies. We argue that the model also provides a reasonable approximation of line-shaped contrail dilution and give an example of how it can be applied in a global climate model.

  5. Parameterization for subgrid-scale motion of ice-shelf calving fronts

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    T. Albrecht

    2011-01-01

    Full Text Available A parameterization for the motion of ice-shelf fronts on a Cartesian grid in finite-difference land-ice models is presented. The scheme prevents artificial thinning of the ice shelf at its edge, which occurs due to the finite resolution of the model. The intuitive numerical implementation diminishes numerical dispersion at the ice front and enables the application of physical boundary conditions to improve the calculation of stress and velocity fields throughout the ice-sheet-shelf system. Numerical properties of this subgrid modification are assessed in the Potsdam Parallel Ice Sheet Model (PISM-PIK for different geometries in one and two horizontal dimensions and are verified against an analytical solution in a flow-line setup.

  6. Numerical dissipation vs. subgrid-scale modelling for large eddy simulation

    Science.gov (United States)

    Dairay, Thibault; Lamballais, Eric; Laizet, Sylvain; Vassilicos, John Christos

    2017-05-01

    This study presents an alternative way to perform large eddy simulation based on a targeted numerical dissipation introduced by the discretization of the viscous term. It is shown that this regularisation technique is equivalent to the use of spectral vanishing viscosity. The flexibility of the method ensures high-order accuracy while controlling the level and spectral features of this purely numerical viscosity. A Pao-like spectral closure based on physical arguments is used to scale this numerical viscosity a priori. It is shown that this way of approaching large eddy simulation is more efficient and accurate than the use of the very popular Smagorinsky model in standard as well as in dynamic version. The main strength of being able to correctly calibrate numerical dissipation is the possibility to regularise the solution at the mesh scale. Thanks to this property, it is shown that the solution can be seen as numerically converged. Conversely, the two versions of the Smagorinsky model are found unable to ensure regularisation while showing a strong sensitivity to numerical errors. The originality of the present approach is that it can be viewed as implicit large eddy simulation, in the sense that the numerical error is the source of artificial dissipation, but also as explicit subgrid-scale modelling, because of the equivalence with spectral viscosity prescribed on a physical basis.

  7. A nonlinear structural subgrid-scale closure for compressible MHD. I. Derivation and energy dissipation properties

    Energy Technology Data Exchange (ETDEWEB)

    Vlaykov, Dimitar G., E-mail: Dimitar.Vlaykov@ds.mpg.de [Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Max-Planck-Institut für Dynamik und Selbstorganisation, Am Faßberg 17, D-37077 Göttingen (Germany); Grete, Philipp [Institut für Astrophysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany); Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany); Schmidt, Wolfram [Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, D-21029 Hamburg (Germany); Schleicher, Dominik R. G. [Departamento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160-C (Chile)

    2016-06-15

    Compressible magnetohydrodynamic (MHD) turbulence is ubiquitous in astrophysical phenomena ranging from the intergalactic to the stellar scales. In studying them, numerical simulations are nearly inescapable, due to the large degree of nonlinearity involved. However, the dynamical ranges of these phenomena are much larger than what is computationally accessible. In large eddy simulations (LESs), the resulting limited resolution effects are addressed explicitly by introducing to the equations of motion additional terms associated with the unresolved, subgrid-scale dynamics. This renders the system unclosed. We derive a set of nonlinear structural closures for the ideal MHD LES equations with particular emphasis on the effects of compressibility. The closures are based on a gradient expansion of the finite-resolution operator [W. K. Yeo (CUP, 1993)] and require no assumptions about the nature of the flow or magnetic field. Thus, the scope of their applicability ranges from the sub- to the hyper-sonic and -Alfvénic regimes. The closures support spectral energy cascades both up and down-scale, as well as direct transfer between kinetic and magnetic resolved and unresolved energy budgets. They implicitly take into account the local geometry, and in particular, the anisotropy of the flow. Their properties are a priori validated in Paper II [P. Grete et al., Phys. Plasmas 23, 062317 (2016)] against alternative closures available in the literature with respect to a wide range of simulation data of homogeneous and isotropic turbulence.

  8. Convective kinetic energy equation under the mass-flux subgrid-scale parameterization

    Science.gov (United States)

    Yano, Jun-Ichi

    2015-03-01

    The present paper originally derives the convective kinetic energy equation under mass-flux subgrid-scale parameterization in a formal manner based on the segmentally-constant approximation (SCA). Though this equation is long since presented by Arakawa and Schubert (1974), a formal derivation is not known in the literature. The derivation of this formulation is of increasing interests in recent years due to the fact that it can explain basic aspects of the convective dynamics such as discharge-recharge and transition from shallow to deep convection. The derivation is presented in two manners: (i) for the case that only the vertical component of the velocity is considered and (ii) the case that both the horizontal and vertical components are considered. The equation reduces to the same form as originally presented by Arakwa and Schubert in both cases, but with the energy dissipation term defined differently. In both cases, nevertheless, the energy "dissipation" (loss) term consists of the three principal contributions: (i) entrainment-detrainment, (ii) outflow from top of convection, and (iii) pressure effects. Additionally, inflow from the bottom of convection contributing to a growth of convection is also formally counted as a part of the dissipation term. The eddy dissipation is also included for a completeness. The order-of-magnitude analysis shows that the convective kinetic energy "dissipation" is dominated by the pressure effects, and it may be approximately described by Rayleigh damping with a constant time scale of the order of 102-103 s. The conclusion is also supported by a supplementary analysis of a cloud-resolving model (CRM) simulation. The Appendix discusses how the loss term ("dissipation") of the convective kinetic energy is qualitatively different from the conventional eddy-dissipation process found in turbulent flows.

  9. A scale-aware subgrid model for quasi-geostrophic turbulence

    Science.gov (United States)

    Bachman, Scott D.; Fox-Kemper, Baylor; Pearson, Brodie

    2017-02-01

    This paper introduces two methods for dynamically prescribing eddy-induced diffusivity, advection, and viscosity appropriate for primitive equation models with resolutions permitting the forward potential enstrophy cascade of quasi-geostrophic dynamics, such as operational ocean models and high-resolution climate models with O>(25>) km horizontal resolution and finer. Where quasi-geostrophic dynamics fail (e.g., the equator, boundary layers, and deep convection), the method reverts to scalings based on a matched two-dimensional enstrophy cascade. A principle advantage is that these subgrid models are scale-aware, meaning that the model is suitable over a range of grid resolutions: from mesoscale grids that just permit baroclinic instabilities to grids below the submesoscale where ageostrophic effects dominate. Two approaches are presented here using Large Eddy Simulation (LES) techniques adapted for three-dimensional rotating, stratified turbulence. The simpler approach has one nondimensional parameter, Λ, which has an optimal value near 1. The second approach dynamically optimizes Λ during simulation using a test filter. The new methods are tested in an idealized scenario by varying the grid resolution, and their use improves the spectra of potential enstrophy and energy in comparison to extant schemes. The new methods keep the gridscale Reynolds and Péclet numbers near 1 throughout the domain, which confers robust numerical stability and minimal spurious diapycnal mixing. Although there are no explicit parameters in the dynamic approach, there is strong sensitivity to the choice of test filter. Designing test filters for heterogeneous ocean turbulence adds cost and uncertainty, and we find the dynamic method does not noticeably improve over setting Λ = 1.

  10. A dynamic subgrid scale model for Large Eddy Simulations based on the Mori-Zwanzig formalism

    Science.gov (United States)

    Parish, Eric J.; Duraisamy, Karthik

    2017-11-01

    The development of reduced models for complex multiscale problems remains one of the principal challenges in computational physics. The optimal prediction framework of Chorin et al. [1], which is a reformulation of the Mori-Zwanzig (M-Z) formalism of non-equilibrium statistical mechanics, provides a framework for the development of mathematically-derived reduced models of dynamical systems. Several promising models have emerged from the optimal prediction community and have found application in molecular dynamics and turbulent flows. In this work, a new M-Z-based closure model that addresses some of the deficiencies of existing methods is developed. The model is constructed by exploiting similarities between two levels of coarse-graining via the Germano identity of fluid mechanics and by assuming that memory effects have a finite temporal support. The appeal of the proposed model, which will be referred to as the 'dynamic-MZ-τ' model, is that it is parameter-free and has a structural form imposed by the mathematics of the coarse-graining process (rather than the phenomenological assumptions made by the modeler, such as in classical subgrid scale models). To promote the applicability of M-Z models in general, two procedures are presented to compute the resulting model form, helping to bypass the tedious error-prone algebra that has proven to be a hindrance to the construction of M-Z-based models for complex dynamical systems. While the new formulation is applicable to the solution of general partial differential equations, demonstrations are presented in the context of Large Eddy Simulation closures for the Burgers equation, decaying homogeneous turbulence, and turbulent channel flow. The performance of the model and validity of the underlying assumptions are investigated in detail.

  11. A nonlinear structural subgrid-scale closure for compressible MHD Part II: a priori comparison on turbulence simulation data

    CERN Document Server

    Grete, P; Schmidt, W; Schleicher, D R G

    2016-01-01

    Even though compressible plasma turbulence is encountered in many astrophysical phenomena, its effect is often not well understood. Furthermore, direct numerical simulations are typically not able to reach the extreme parameters of these processes. For this reason, large-eddy simulations (LES), which only simulate large and intermediate scales directly, are employed. The smallest, unresolved scales and the interactions between small and large scales are introduced by means of a subgrid-scale (SGS) model. We propose and verify a new set of nonlinear SGS closures for future application as an SGS model in LES of compressible magnetohydrodynamics (MHD). We use 15 simulations (without explicit SGS model) of forced, isotropic, homogeneous turbulence with varying sonic Mach number $\\mathrm{M_s} = 0.2$ to $20$ as reference data for the most extensive \\textit{a priori} tests performed so far in literature. In these tests we explicitly filter the reference data and compare the performance of the new closures against th...

  12. Assessment of subgrid-scale models with a large-eddy simulation-dedicated experimental database: The pulsatile impinging jet in turbulent cross-flow

    Science.gov (United States)

    Baya Toda, Hubert; Cabrit, Olivier; Truffin, Karine; Bruneaux, Gilles; Nicoud, Franck

    2014-07-01

    Large-Eddy Simulation (LES) in complex geometries and industrial applications like piston engines, gas turbines, or aircraft engines requires the use of advanced subgrid-scale (SGS) models able to take into account the main flow features and the turbulence anisotropy. Keeping this goal in mind, this paper reports a LES-dedicated experiment of a pulsatile hot-jet impinging a flat-plate in the presence of a cold turbulent cross-flow. Unlike commonly used academic test cases, this configuration involves different flow features encountered in complex configurations: shear/rotating regions, stagnation point, wall-turbulence, and the propagation of a vortex ring along the wall. This experiment was also designed with the aim to use quantitative and nonintrusive optical diagnostics such as Particle Image Velocimetry, and to easily perform a LES involving a relatively simple geometry and well-controlled boundary conditions. Hence, two eddy-viscosity-based SGS models are investigated: the dynamic Smagorinsky model [M. Germano, U. Piomelli, P. Moin, and W. Cabot, "A dynamic subgrid-scale eddy viscosity model," Phys. Fluids A 3(7), 1760-1765 (1991)] and the σ-model [F. Nicoud, H. B. Toda, O. Cabrit, S. Bose, and J. Lee, "Using singular values to build a subgrid-scale model for large eddy simulations," Phys. Fluids 23(8), 085106 (2011)]. Both models give similar results during the first phase of the experiment. However, it was found that the dynamic Smagorinsky model could not accurately predict the vortex-ring propagation, while the σ-model provides a better agreement with the experimental measurements. Setting aside the implementation of the dynamic procedure (implemented here in its simplest form, i.e., without averaging over homogeneous directions and with clipping of negative values to ensure numerical stability), it is suggested that the mitigated predictions of the dynamic Smagorinsky model are due to the dynamic constant, which strongly depends on the mesh resolution

  13. A nonlinear structural subgrid-scale closure for compressible MHD Part I: derivation and energy dissipation properties

    CERN Document Server

    Vlaykov, Dimitar G; Schmidt, Wolfram; Schleicher, Dominik R G

    2016-01-01

    Compressible magnetohydrodynamic (MHD) turbulence is ubiquitous in astrophysical phenomena ranging from the intergalactic to the stellar scales. In studying them, numerical simulations are nearly inescapable, due to the large degree of nonlinearity involved. However the dynamical ranges of these phenomena are much larger than what is computationally accessible. In large eddy simulations (LES), the resulting limited resolution effects are addressed explicitly by introducing to the equations of motion additional terms associated with the unresolved, subgrid-scale (SGS) dynamics. This renders the system unclosed. We derive a set of nonlinear structural closures for the ideal MHD LES equations with particular emphasis on the effects of compressibility. The closures are based on a gradient expansion of the finite-resolution operator (W.K. Yeo CUP 1993, ed. Galperin & Orszag) and require no assumptions about the nature of the flow or magnetic field. Thus the scope of their applicability ranges from the sub- to ...

  14. One-equation sub-grid scale (SGS) modelling for Euler-Euler large eddy simulation (EELES) of dispersed bubbly flow

    NARCIS (Netherlands)

    Niceno, B.; Dhotre, M.T.; Deen, N.G.

    2008-01-01

    In this work, we have presented a one-equation model for sub-grid scale (SGS) kinetic energy and applied it for an Euler-Euler large eddy simulation (EELES) of a bubble column reactor. The one-equation model for SGS kinetic energy shows improved predictions over the state-of-the-art dynamic

  15. Impact of Sub-grid Soil Textural Properties on Simulations of Hydrological Fluxes at the Continental Scale Mississippi River Basin

    Science.gov (United States)

    Kumar, R.; Samaniego, L. E.; Livneh, B.

    2013-12-01

    Knowledge of soil hydraulic properties such as porosity and saturated hydraulic conductivity is required to accurately model the dynamics of near-surface hydrological processes (e.g. evapotranspiration and root-zone soil moisture dynamics) and provide reliable estimates of regional water and energy budgets. Soil hydraulic properties are commonly derived from pedo-transfer functions using soil textural information recorded during surveys, such as the fractions of sand and clay, bulk density, and organic matter content. Typically large scale land-surface models are parameterized using a relatively coarse soil map with little or no information on parametric sub-grid variability. In this study we analyze the impact of sub-grid soil variability on simulated hydrological fluxes over the Mississippi River Basin (≈3,240,000 km2) at multiple spatio-temporal resolutions. A set of numerical experiments were conducted with the distributed mesoscale hydrologic model (mHM) using two soil datasets: (a) the Digital General Soil Map of the United States or STATSGO2 (1:250 000) and (b) the recently collated Harmonized World Soil Database based on the FAO-UNESCO Soil Map of the World (1:5 000 000). mHM was parameterized with the multi-scale regionalization technique that derives distributed soil hydraulic properties via pedo-transfer functions and regional coefficients. Within the experimental framework, the 3-hourly model simulations were conducted at four spatial resolutions ranging from 0.125° to 1°, using meteorological datasets from the NLDAS-2 project for the time period 1980-2012. Preliminary results indicate that the model was able to capture observed streamflow behavior reasonably well with both soil datasets, in the major sub-basins (i.e. the Missouri, the Upper Mississippi, the Ohio, the Red, and the Arkansas). However, the spatio-temporal patterns of simulated water fluxes and states (e.g. soil moisture, evapotranspiration) from both simulations, showed marked

  16. A Physically Based Horizontal Subgrid-scale Turbulent Mixing Parameterization for the Convective Boundary Layer in Mesoscale Models

    Science.gov (United States)

    Zhou, Bowen; Xue, Ming; Zhu, Kefeng

    2017-04-01

    Compared to the representation of vertical turbulent mixing through various PBL schemes, the treatment of horizontal turbulence mixing in the boundary layer within mesoscale models, with O(10) km horizontal grid spacing, has received much less attention. In mesoscale models, subgrid-scale horizontal fluxes most often adopt the gradient-diffusion assumption. The horizontal mixing coefficients are usually set to a constant, or through the 2D Smagorinsky formulation, or in some cases based on the 1.5-order turbulence kinetic energy (TKE) closure. In this work, horizontal turbulent mixing parameterizations using physically based characteristic velocity and length scales are proposed for the convective boundary layer based on analysis of a well-resolved, wide-domain large-eddy simulation (LES). The proposed schemes involve different levels of sophistication. The first two schemes can be used together with first-order PBL schemes, while the third uses TKE to define its characteristic velocity scale and can be used together with TKE-based higher-order PBL schemes. The current horizontal mixing formulations are also assessed a priori through the filtered LES results to illustrate their limitations. The proposed parameterizations are tested a posteriori in idealized simulations of turbulent dispersion of a passive scalar. Comparisons show improved horizontal dispersion by the proposed schemes, and further demonstrate the weakness of the current schemes.

  17. Resolution-dependent behavior of subgrid-scale vertical transport in the Zhang-McFarlane convection parameterization

    Science.gov (United States)

    Xiao, Heng; Gustafson, William I.; Hagos, Samson M.; Wu, Chien-Ming; Wan, Hui

    2015-06-01

    To better understand the behavior of quasi-equilibrium-based convection parameterizations at higher resolution, we use a diagnostic framework to examine the resolution-dependence of subgrid-scale vertical transport of moist static energy as parameterized by the Zhang-McFarlane convection parameterization (ZM). Grid-scale input to ZM is supplied by coarsening output from cloud-resolving model (CRM) simulations onto subdomains ranging in size from 8 × 8 to 256 × 256 km2. Then the ZM-based parameterization of vertical transport of moist static energy for scales smaller than the subdomain size (w'h'>¯ZM) are compared to those directly calculated from the CRM simulations (w'h'>¯CRM) for different subdomain sizes. The ensemble mean w'h'>¯CRM decreases by more than half as the subdomain size decreases from 128 to 8 km across while w'h'>¯ZM decreases with subdomain size only for strong convection cases and increases for weaker cases. The resolution dependence of w'h'>¯ZM is determined by the positive-definite grid-scale tendency of convective available potential energy (CAPE) in the convective quasi-equilibrium (QE) closure. Further analysis shows the actual grid-scale tendency of CAPE (before taking the positive definite value) and w'h'>¯CRM behave very similarly as the subdomain size changes because they are both tied to grid-scale advective tendencies. We can improve the resolution dependence of w'h'>¯ZM significantly by averaging the grid-scale tendency of CAPE over an appropriately large area surrounding each subdomain before taking its positive definite value. Even though the ensemble mean w'h'>¯CRM decreases with increasing resolution, its variability increases dramatically. w'h'>¯ZM cannot capture such increase in the variability, suggesting the need for stochastic treatment of convection at relatively high spatial resolution (8 or 16 km).

  18. Final Report. Evaluating the Climate Sensitivity of Dissipative Subgrid-Scale Mixing Processes and Variable Resolution in NCAR's Community Earth System Model

    Energy Technology Data Exchange (ETDEWEB)

    Jablonowski, Christiane [Univ. of Michigan, Ann Arbor, MI (United States)

    2015-12-14

    The goals of this project were to (1) assess and quantify the sensitivity and scale-dependency of unresolved subgrid-scale mixing processes in NCAR’s Community Earth System Model (CESM), and (2) to improve the accuracy and skill of forthcoming CESM configurations on modern cubed-sphere and variable-resolution computational grids. The research thereby contributed to the description and quantification of uncertainties in CESM’s dynamical cores and their physics-dynamics interactions.

  19. Intercomparison of different subgrid-scale models for the Large Eddy Simulation of the diurnal evolution of the atmospheric boundary layer during the Wangara experiment

    Science.gov (United States)

    Dall'Ozzo, C.; Carissimo, B.; Musson-Genon, L.; Dupont, E.; Milliez, M.

    2012-04-01

    The study of a whole diurnal cycle of the atmospheric boundary layer evolving through unstable, neutral and stable states is essential to test a model applicable to the dispersion of pollutants. Consequently a LES of a diurnal cycle is performed and compared to observations from the Wangara experiment (Day 33-34). All simulations are done with Code_Saturne [1] an open source CFD code. The synthetic eddy method (SEM) [2] is implemented to initialize turbulence at the beginning of the simulation. Two different subgrid-scale (SGS) models are tested: the Smagorinsky model [3],[4] and the dynamical Wong and Lilly model [5]. The first one, the most classical, uses a Smagorinsky constant Cs to parameterize the dynamical turbulent viscosity while the second one relies on a variable C. Cs remains insensitive to the atmospheric stability level in contrary to the parameter C determined by the Wong and Lilly model. It is based on the error minimization of the difference between the tensors of the resolved turbulent stress (Lij) and the difference of the SGS stress tensors at two different filter scales (Mij). Furthermore, the thermal eddy diffusivity, as opposed to the Smagorinsky model, is calculated with a dynamical Prandtl number determination. The results are confronted to previous simulations from Basu et al. (2008) [6], using a locally averaged scale-dependent dynamic (LASDD) SGS model, and to previous RANS simulations. The accuracy in reproducing the experimental atmospheric conditions is discussed, especially regarding the night time low-level jet formation. In addition, the benefit of the utilization of a coupled radiative model is discussed.

  20. Large Eddy Simulation of an SD7003 Airfoil: Effects of Reynolds number and Subgrid-scale modeling

    Science.gov (United States)

    Sarlak, Hamid

    2017-05-01

    This paper presents results of a series of numerical simulations in order to study aerodynamic characteristics of the low Reynolds number Selig-Donovan airfoil, SD7003. Large Eddy Simulation (LES) technique is used for all computations at chord-based Reynolds numbers 10,000, 24,000 and 60,000 and simulations have been performed to primarily investigate the role of sub-grid scale (SGS) modeling on the dynamics of flow generated over the airfoil, which has not been dealt with in great detail in the past. It is seen that simulations are increasingly getting influenced by SGS modeling with increasing the Reynolds number, and the effect is visible even at a relatively low chord-Reynolds number of 60,000. Among the tested models, the dynamic Smagorinsky gives the poorest predictions of the flow, with overprediction of lift and a larger separation on airfoils suction side. Among various models, the implicit LES offers closest pressure distribution predictions compared with literature.

  1. A new mixed subgrid-scale model for large eddy simulation of turbulent drag-reducing flows of viscoelastic fluids

    Science.gov (United States)

    Li, Feng-Chen; Wang, Lu; Cai, Wei-Hua

    2015-07-01

    A mixed subgrid-scale (SGS) model based on coherent structures and temporal approximate deconvolution (MCT) is proposed for turbulent drag-reducing flows of viscoelastic fluids. The main idea of the MCT SGS model is to perform spatial filtering for the momentum equation and temporal filtering for the conformation tensor transport equation of turbulent flow of viscoelastic fluid, respectively. The MCT model is suitable for large eddy simulation (LES) of turbulent drag-reducing flows of viscoelastic fluids in engineering applications since the model parameters can be easily obtained. The LES of forced homogeneous isotropic turbulence (FHIT) with polymer additives and turbulent channel flow with surfactant additives based on MCT SGS model shows excellent agreements with direct numerical simulation (DNS) results. Compared with the LES results using the temporal approximate deconvolution model (TADM) for FHIT with polymer additives, this mixed SGS model MCT behaves better, regarding the enhancement of calculating parameters such as the Reynolds number. For scientific and engineering research, turbulent flows at high Reynolds numbers are expected, so the MCT model can be a more suitable model for the LES of turbulent drag-reducing flows of viscoelastic fluid with polymer or surfactant additives. Project supported by the China Postdoctoral Science Foundation (Grant No. 2011M500652), the National Natural Science Foundation of China (Grant Nos. 51276046 and 51206033), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20112302110020).

  2. Assessment of sub-grid scale dispersion closure with regularized deconvolution method in a particle-laden turbulent jet

    Science.gov (United States)

    Wang, Qing; Zhao, Xinyu; Ihme, Matthias

    2017-11-01

    Particle-laden turbulent flows are important in numerous industrial applications, such as spray combustion engines, solar energy collectors etc. It is of interests to study this type of flows numerically, especially using large-eddy simulations (LES). However, capturing the turbulence-particle interaction in LES remains challenging due to the insufficient representation of the effect of sub-grid scale (SGS) dispersion. In the present work, a closure technique for the SGS dispersion using regularized deconvolution method (RDM) is assessed. RDM was proposed as the closure for the SGS dispersion in a counterflow spray that is studied numerically using finite difference method on a structured mesh. A presumed form of LES filter is used in the simulations. In the present study, this technique has been extended to finite volume method with an unstructured mesh, where no presumption on the filter form is required. The method is applied to a series of particle-laden turbulent jets. Parametric analyses of the model performance are conducted for flows with different Stokes numbers and Reynolds numbers. The results from LES will be compared against experiments and direct numerical simulations (DNS).

  3. On the Effect of an Anisotropy-Resolving Subgrid-Scale Model on Turbulent Vortex Motions

    Science.gov (United States)

    2014-09-19

    expression coincides with the modified Leonard stress proposed by Ger- mano et al. (1991). In this model, the SGS turbulence energy kSGS may be evaluated as... mano subgridscale closure method. Phys. Fluids A, Vol. 4, pp. 633-635. Morinishi, Y. and Vasilyev, O.V. (2001), A recommended modification to the

  4. Effect of Considering Sub-Grid Scale Uncertainties on the Forecasts of a High-Resolution Limited Area Ensemble Prediction System

    Science.gov (United States)

    Kim, SeHyun; Kim, Hyun Mee

    2017-05-01

    The ensemble prediction system (EPS) is widely used in research and at operation center because it can represent the uncertainty of predicted atmospheric state and provide information of probabilities. The high-resolution (so-called "convection-permitting") limited area EPS can represent the convection and turbulence related to precipitation phenomena in more detail, but it is also much sensitive to small-scale or sub-grid scale processes. The convection and turbulence are represented using physical processes in the model and model errors occur due to sub-grid scale processes that were not resolved. This study examined the effect of considering sub-grid scale uncertainties using the high-resolution limited area EPS of the Korea Meteorological Administration (KMA). The developed EPS has horizontal resolution of 3 km and 12 ensemble members. The initial and boundary conditions were provided by the global model. The Random Parameters (RP) scheme was used to represent sub-grid scale uncertainties. The EPSs with and without the RP scheme were developed and the results were compared. During the one month period of July, 2013, a significant difference was shown in the spread of 1.5 m temperature and the Root Mean Square Error and spread of 10 m zonal wind due to application of the RP scheme. For precipitation forecast, the precipitation tended to be overestimated relative to the observation when the RP scheme was applied. Moreover, the forecast became more accurate for heavy precipitations and the longer forecast lead times. For two heavy rainfall cases occurred during the research period, the higher Equitable Threat Score was observed for heavy precipitations in the system with the RP scheme compared to the one without, demonstrating consistency with the statistical results for the research period. Therefore, the predictability for heavy precipitation phenomena that affected the Korean Peninsula increases if the RP scheme is used to consider sub-grid scale uncertainties

  5. Sub-grid scale models for discontinuous Galerkin methods based on the Mori-Zwanzig formalism

    Science.gov (United States)

    Parish, Eric; Duraisamy, Karthk

    2017-11-01

    The optimal prediction framework of Chorin et al., which is a reformulation of the Mori-Zwanzig (M-Z) formalism of non-equilibrium statistical mechanics, provides a framework for the development of mathematically-derived closure models. The M-Z formalism provides a methodology to reformulate a high-dimensional Markovian dynamical system as a lower-dimensional, non-Markovian (non-local) system. In this lower-dimensional system, the effects of the unresolved scales on the resolved scales are non-local and appear as a convolution integral. The non-Markovian system is an exact statement of the original dynamics and is used as a starting point for model development. In this work, we investigate the development of M-Z-based closures model within the context of the Variational Multiscale Method (VMS). The method relies on a decomposition of the solution space into two orthogonal subspaces. The impact of the unresolved subspace on the resolved subspace is shown to be non-local in time and is modeled through the M-Z-formalism. The models are applied to hierarchical discontinuous Galerkin discretizations. Commonalities between the M-Z closures and conventional flux schemes are explored. This work was supported in part by AFOSR under the project ''LES Modeling of Non-local effects using Statistical Coarse-graining'' with Dr. Jean-Luc Cambier as the technical monitor.

  6. Simple lattice Boltzmann subgrid-scale model for convectional flows with high Rayleigh numbers within an enclosed circular annular cavity

    Science.gov (United States)

    Chen, Sheng; Tölke, Jonas; Krafczyk, Manfred

    2009-08-01

    Natural convection within an enclosed circular annular cavity formed by two concentric vertical cylinders is of fundamental interest and practical importance. Generally, the assumption of axisymmetric thermal flow is adopted for simulating such natural convections and the validity of the assumption of axisymmetric thermal flow is still held even for some turbulent convection. Usually the Rayleigh numbers (Ra) of realistic flows are very high. However, the work to design suitable and efficient lattice Boltzmann (LB) models on such flows is quite rare. To bridge the gap, in this paper a simple LB subgrid-scale (SGS) model, which is based on our recent work [S. Chen, J. Tölke, and M. Krafczyk, Phys. Rev. E 79, 016704 (2009); S. Chen, J. Tölke, S. Geller, and M. Krafczyk, Phys. Rev. E 78, 046703 (2008)], is proposed for simulating convectional flow with high Ra within an enclosed circular annular cavity. The key parameter for the SGS model can be quite easily and efficiently evaluated by the present model. The numerical experiments demonstrate that the present model works well for a large range of Ra and Prandtl number (Pr). Though in the present study a popularly used static Smagorinsky turbulence model is adopted to demonstrate how to develop a LB SGS model for simulating axisymmetric thermal flows with high Ra, other state-of-the-art turbulence models can be incorporated into the present model in the same way. In addition, the present model can be extended straightforwardly to simulate other axisymmetric convectional flows with high Ra, for example, turbulent convection with internal volumetric heat generation in a vertical cylinder, which is an important simplified representation of a nuclear reactor.

  7. A Dynamic Subgrid Scale Model for Large Eddy Simulations Based on the Mori-Zwanzig Formalism

    CERN Document Server

    Parish, Eric J

    2016-01-01

    The development of reduced models for complex systems that lack scale separation remains one of the principal challenges in computational physics. The optimal prediction framework of Chorin et al., which is a reformulation of the Mori-Zwanzig (M-Z) formalism of non-equilibrium statistical mechanics, provides a methodology for the development of mathematically-derived reduced models of dynamical systems. Several promising models have emerged from the optimal prediction community and have found application in molecular dynamics and turbulent flows. In this work, a novel M-Z-based closure model that addresses some of the deficiencies of existing methods is developed. The model is constructed by exploiting similarities between two levels of coarse-graining via the Germano identity of fluid mechanics and by assuming that memory effects have a finite temporal support. The appeal of the proposed model, which will be referred to as the `dynamic-$\\tau$' model, is that it is parameter-free and has a structural form imp...

  8. Sub-grid scale representation of vegetation in global land surface schemes: implications for estimation of the terrestrial carbon sink

    Directory of Open Access Journals (Sweden)

    J. R. Melton

    2014-02-01

    Full Text Available Terrestrial ecosystem models commonly represent vegetation in terms of plant functional types (PFTs and use their vegetation attributes in calculations of the energy and water balance as well as to investigate the terrestrial carbon cycle. Sub-grid scale variability of PFTs in these models is represented using different approaches with the "composite" and "mosaic" approaches being the two end-members. The impact of these two approaches on the global carbon balance has been investigated with the Canadian Terrestrial Ecosystem Model (CTEM v 1.2 coupled to the Canadian Land Surface Scheme (CLASS v 3.6. In the composite (single-tile approach, the vegetation attributes of different PFTs present in a grid cell are aggregated and used in calculations to determine the resulting physical environmental conditions (soil moisture, soil temperature, etc. that are common to all PFTs. In the mosaic (multi-tile approach, energy and water balance calculations are performed separately for each PFT tile and each tile's physical land surface environmental conditions evolve independently. Pre-industrial equilibrium CLASS-CTEM simulations yield global totals of vegetation biomass, net primary productivity, and soil carbon that compare reasonably well with observation-based estimates and differ by less than 5% between the mosaic and composite configurations. However, on a regional scale the two approaches can differ by > 30%, especially in areas with high heterogeneity in land cover. Simulations over the historical period (1959–2005 show different responses to evolving climate and carbon dioxide concentrations from the two approaches. The cumulative global terrestrial carbon sink estimated over the 1959–2005 period (excluding land use change (LUC effects differs by around 5% between the two approaches (96.3 and 101.3 Pg, for the mosaic and composite approaches, respectively and compares well with the observation-based estimate of 82.2 ± 35 Pg C over the same

  9. An explicit relaxation filtering framework based upon Perona-Malik anisotropic diffusion for shock capturing and subgrid scale modeling of Burgers turbulence

    CERN Document Server

    Maulik, Romit

    2016-01-01

    In this paper, we introduce a relaxation filtering closure approach to account for subgrid scale effects in explicitly filtered large eddy simulations using the concept of anisotropic diffusion. We utilize the Perona-Malik diffusion model and demonstrate its shock capturing ability and spectral performance for solving the Burgers turbulence problem, which is a simplified prototype for more realistic turbulent flows showing the same quadratic nonlinearity. Our numerical assessments present the behavior of various diffusivity functions in conjunction with a detailed sensitivity analysis with respect to the free modeling parameters. In comparison to direct numerical simulation (DNS) and under-resolved DNS results, we find that the proposed closure model is efficient in the prevention of energy accumulation at grid cut-off and is also adept at preventing any possible spurious numerical oscillations due to shock formation under the optimal parameter choices. In contrast to other relaxation filtering approaches, it...

  10. Recursive renormalization group theory based subgrid modeling

    Science.gov (United States)

    Zhou, YE

    1991-01-01

    Advancing the knowledge and understanding of turbulence theory is addressed. Specific problems to be addressed will include studies of subgrid models to understand the effects of unresolved small scale dynamics on the large scale motion which, if successful, might substantially reduce the number of degrees of freedom that need to be computed in turbulence simulation.

  11. Large Eddy Simulations of a Premixed Jet Combustor Using Flamelet-Generated Manifolds: Effects of Heat Loss and Subgrid-Scale Models

    KAUST Repository

    Hernandez Perez, Francisco E.

    2017-01-05

    Large eddy simulations of a turbulent premixed jet flame in a confined chamber were conducted using the flamelet-generated manifold technique for chemistry tabulation. The configuration is characterized by an off-center nozzle having an inner diameter of 10 mm, supplying a lean methane-air mixture with an equivalence ratio of 0.71 and a mean velocity of 90 m/s, at 573 K and atmospheric pressure. Conductive heat loss is accounted for in the manifold via burner-stabilized flamelets and the subgrid-scale (SGS) turbulencechemistry interaction is modeled via presumed probability density functions. Comparisons between numerical results and measured data show that a considerable improvement in the prediction of temperature is achieved when heat losses are included in the manifold, as compared to the adiabatic one. Additional improvement in the temperature predictions is obtained by incorporating radiative heat losses. Moreover, further enhancements in the LES predictions are achieved by employing SGS models based on transport equations, such as the SGS turbulence kinetic energy equation with dynamic coefficients. While the numerical results display good agreement up to a distance of 4 nozzle diameters downstream of the nozzle exit, the results become less satisfactory along the downstream, suggesting that further improvements in the modeling are required, among which a more accurate model for the SGS variance of progress variable can be relevant.

  12. Advanced subgrid-scale modeling for convection-dominated species transport at fluid interfaces with application to mass transfer from rising bubbles

    Science.gov (United States)

    Weiner, Andre; Bothe, Dieter

    2017-10-01

    This paper presents a novel subgrid scale (SGS) model for simulating convection-dominated species transport at deformable fluid interfaces. One possible application is the Direct Numerical Simulation (DNS) of mass transfer from rising bubbles. The transport of a dissolving gas along the bubble-liquid interface is determined by two transport phenomena: convection in streamwise direction and diffusion in interface normal direction. The convective transport for technical bubble sizes is several orders of magnitude higher, leading to a thin concentration boundary layer around the bubble. A true DNS, fully resolving hydrodynamic and mass transfer length scales results in infeasible computational costs. Our approach is therefore a DNS of the flow field combined with a SGS model to compute the mass transfer between bubble and liquid. An appropriate model-function is used to compute the numerical fluxes on all cell faces of an interface cell. This allows to predict the mass transfer correctly even if the concentration boundary layer is fully contained in a single cell layer around the interface. We show that the SGS-model reduces the resolution requirements at the interface by a factor of ten and more. The integral flux correction is also applicable to other thin boundary layer problems. Two flow regimes are investigated to validate the model. A semi-analytical solution for creeping flow is used to assess local and global mass transfer quantities. For higher Reynolds numbers ranging from Re = 100 to Re = 460 and Péclet numbers between Pe =104 and Pe = 4 ṡ106 we compare the global Sherwood number against correlations from literature. In terms of accuracy, the predicted mass transfer never deviates more than 4% from the reference values.

  13. High-Resolution Global Modeling of the Effects of Subgrid-Scale Clouds and Turbulence on Precipitating Cloud Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bogenschutz, Peter [National Center for Atmospheric Research, Boulder, CO (United States); Moeng, Chin-Hoh [National Center for Atmospheric Research, Boulder, CO (United States)

    2015-10-13

    The PI’s at the National Center for Atmospheric Research (NCAR), Chin-Hoh Moeng and Peter Bogenschutz, have primarily focused their time on the implementation of the Simplified-Higher Order Turbulence Closure (SHOC; Bogenschutz and Krueger 2013) to the Multi-scale Modeling Framework (MMF) global model and testing of SHOC on deep convective cloud regimes.

  14. Impact of an additional radiative CO2 cooling induced by subgrid-scale gravity waves in the middle and upper atmosphere

    Science.gov (United States)

    Medvedev, A. S.; Yigit, E.; Kutepov, A.; Feofilov, A.

    2011-12-01

    Atmospheric fluctuations produced by GWs are a substantial source of momentum and energy in the thermosphere (Yigit et al., 2009). These fluctuations also affect radiative transfer and, ultimately, the radiative heating/cooling rates. Recently, Kutepov et al. (2007) developed a methodology to account for radiative effects of subgrid-scale GWs not captured by general circulation models (GCMs). It has been extended by Kutepov et al (2011) to account not only for wave-induced variations of temperature, but also of CO2 and atomic oxygen. It was shown that these GWs can cause additional cooling of up to 3 K/day around mesopause. A key parameter for calculating the additional cooling is the temperature variance associated with GWs, which is a subproduct of conventional GW schemes. In this study, the parameterization of Kutepov et al. (2011) has been implemented into a 3-D comprehensive GCM that incorporates the effects of unresolved GWs via the extended nonlinear scheme of Yigit et al. (2008). Simulated net effects of the additional radiative CO2 cooling on the temperature and wind in the mesosphere and lower thermosphere are presented and discussed for solstice conditions. 1. Kutepov, A. A, A. G. Feofilov, A. S. Medvedev, A. W. A. Pauldrach, and P. Hartogh (2007), Geophys. Res. Lett. 34, L24807, doi:10.1029/2007GL032392. 2. Kutepov, A. A., A. G. Feofilov, A. S. Medvedev, U. Berger, and M. Kaufmann (2011), submitted to Geophys. Res. Letts. 3. Yigit, E., A. D. Aylward, and A. S. Medvedev (2008), J. Geophys. Res., 113, D19106, doi:10.1029/2008JD010135. 4. Yigit, E., A. S. Medvedev, A. D. Aylward, P. Hartogh, and M. J. Harris (2009), J. Geophys. Res., 114, D07101, doi:10.1029/2008JD011132.

  15. Modeling lightning-NOx chemistry on a sub-grid scale in a global chemical transport model

    Directory of Open Access Journals (Sweden)

    A. Gressent

    2016-05-01

    Full Text Available For the first time, a plume-in-grid approach is implemented in a chemical transport model (CTM to parameterize the effects of the nonlinear reactions occurring within high concentrated NOx plumes from lightning NOx emissions (LNOx in the upper troposphere. It is characterized by a set of parameters including the plume lifetime, the effective reaction rate constant related to NOx–O3 chemical interactions, and the fractions of NOx conversion into HNO3 within the plume. Parameter estimates were made using the Dynamical Simple Model of Atmospheric Chemical Complexity (DSMACC box model, simple plume dispersion simulations, and the 3-D Meso-NH (non-hydrostatic mesoscale atmospheric model. In order to assess the impact of the LNOx plume approach on the NOx and O3 distributions on a large scale, simulations for the year 2006 were performed using the GEOS-Chem global model with a horizontal resolution of 2° × 2.5°. The implementation of the LNOx parameterization implies an NOx and O3 decrease on a large scale over the region characterized by a strong lightning activity (up to 25 and 8 %, respectively, over central Africa in July and a relative increase downwind of LNOx emissions (up to 18 and 2 % for NOx and O3, respectively, in July. The calculated variability in NOx and O3 mixing ratios around the mean value according to the known uncertainties in the parameter estimates is at a maximum over continental tropical regions with ΔNOx [−33.1, +29.7] ppt and ΔO3 [−1.56, +2.16] ppb, in January, and ΔNOx [−14.3, +21] ppt and ΔO3 [−1.18, +1.93] ppb, in July, mainly depending on the determination of the diffusion properties of the atmosphere and the initial NO mixing ratio injected by lightning. This approach allows us (i to reproduce a more realistic lightning NOx chemistry leading to better NOx and O3 distributions on the large scale and (ii to focus on other improvements to reduce remaining uncertainties from processes

  16. Effect of reactions in small eddies on biomass gasification with eddy dissipation concept - Sub-grid scale reaction model.

    Science.gov (United States)

    Chen, Juhui; Yin, Weijie; Wang, Shuai; Meng, Cheng; Li, Jiuru; Qin, Bai; Yu, Guangbin

    2016-07-01

    Large-eddy simulation (LES) approach is used for gas turbulence, and eddy dissipation concept (EDC)-sub-grid scale (SGS) reaction model is employed for reactions in small eddies. The simulated gas molar fractions are in better agreement with experimental data with EDC-SGS reaction model. The effect of reactions in small eddies on biomass gasification is emphatically analyzed with EDC-SGS reaction model. The distributions of the SGS reaction rates which represent the reactions in small eddies with particles concentration and temperature are analyzed. The distributions of SGS reaction rates have the similar trend with those of total reactions rates and the values account for about 15% of the total reactions rates. The heterogeneous reaction rates with EDC-SGS reaction model are also improved during the biomass gasification process in bubbling fluidized bed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Predicting the impacts of fishing canals on Floodplain Dynamics in Northern Cameroon using a small-scale sub-grid hydraulic model

    Science.gov (United States)

    Shastry, A. R.; Durand, M. T.; Fernandez, A.; Hamilton, I.; Kari, S.; Labara, B.; Laborde, S.; Mark, B. G.; Moritz, M.; Neal, J. C.; Phang, S. C.

    2015-12-01

    Modeling Regime Shifts in the Logone floodplain (MORSL) is an ongoing interdisciplinary project at The Ohio State University studying the ecological, social and hydrological system of the region. This floodplain, located in Northern Cameroon, is part of the Lake Chad basin. Between September and October the floodplain is inundated by the overbank flow from the Logone River, which is important for agriculture and fishing. Fishermen build canals to catch fish during the flood's recession to the river by installing fishnets at the intersection of the canals and the river. Fishing canals thus connect the river to natural depressions of the terrain, which act as seasonal ponds during this part of the year. Annual increase in the number of canals affect hydraulics and hence fishing in the region. In this study, the Bara region (1 km2) of the Logone floodplain, through which Lorome Mazra flows, is modeled using LISFLOOD-FP, a raster-based model with sub-grid parameterizations of canals. The aim of the study is to find out how the small-scale, local features like canals and fishnets govern the flow, so that it can be incorporated in a large-scale model of the floodplain at a coarser spatial resolution. We will also study the effect of increasing number of canals on the flooding pattern. We use a simplified version of the hydraulic system at a grid-cell size of 30-m, using synthetic topography, parameterized fishing canals, and representing fishnets as trash screens. The inflow at Bara is obtained from a separate, lower resolution (1-km grid-cell) model run, which is forced by daily discharge records obtained from Katoa, located about 25-km to the south of Bara. The model appropriately captures the rise and recession of the annual flood, supporting use of the LISFLOOD-FP approach. Predicted water levels at specific points in the river, the canals, the depression and the floodplain will be compared to field measured heights of flood recession in Bara, November 2014.

  18. Efficient non-hydrostatic modelling of 3D wave-induced currents using a subgrid approach

    Science.gov (United States)

    Rijnsdorp, Dirk P.; Smit, Pieter B.; Zijlema, Marcel; Reniers, Ad J. H. M.

    2017-08-01

    Wave-induced currents are an ubiquitous feature in coastal waters that can spread material over the surf zone and the inner shelf. These currents are typically under resolved in non-hydrostatic wave-flow models due to computational constraints. Specifically, the low vertical resolutions adequate to describe the wave dynamics - and required to feasibly compute at the scales of a field site - are too coarse to account for the relevant details of the three-dimensional (3D) flow field. To describe the relevant dynamics of both wave and currents, while retaining a model framework that can be applied at field scales, we propose a two grid approach to solve the governing equations. With this approach, the vertical accelerations and non-hydrostatic pressures are resolved on a relatively coarse vertical grid (which is sufficient to accurately resolve the wave dynamics), whereas the horizontal velocities and turbulent stresses are resolved on a much finer subgrid (of which the resolution is dictated by the vertical scale of the mean flows). This approach ensures that the discrete pressure Poisson equation - the solution of which dominates the computational effort - is evaluated on the coarse grid scale, thereby greatly improving efficiency, while providing a fine vertical resolution to resolve the vertical variation of the mean flow. This work presents the general methodology, and discusses the numerical implementation in the SWASH wave-flow model. Model predictions are compared with observations of three flume experiments to demonstrate that the subgrid approach captures both the nearshore evolution of the waves, and the wave-induced flows like the undertow profile and longshore current. The accuracy of the subgrid predictions is comparable to fully resolved 3D simulations - but at much reduced computational costs. The findings of this work thereby demonstrate that the subgrid approach has the potential to make 3D non-hydrostatic simulations feasible at the scale of a

  19. Birefringent dispersive FDTD subgridding scheme

    OpenAIRE

    De Deckere, B; Van Londersele, Arne; De Zutter, Daniël; Vande Ginste, Dries

    2016-01-01

    A novel 2D finite difference time domain (FDTD) subgridding method is proposed, only subject to the Courant limit of the coarse grid. By making mu or epsilon inside the subgrid dispersive, unconditional stability is induced at the cost of a sparse, implicit set of update equations. By only adding dispersion along preferential directions, it is possible to dramatically reduce the rank of the matrix equation that needs to be solved.

  20. A Fast and Accurate Scheme for Sea Ice Dynamics with a Stochastic Subgrid Model

    Science.gov (United States)

    Seinen, C.; Khouider, B.

    2016-12-01

    Sea ice physics is a very complex process occurring over a wide range of scales; such as local melting or large scale drift. At the current grid resolution of Global Climate Models (GCMs), we are able to resolve large scale sea ice dynamics but uncertainty remains due to subgrid physics and potential dynamic feedback, especially due to the formation of melt ponds. Recent work in atmospheric science has shown success of Markov Jump stochastic subgrid models in the representation of clouds and convection and their feedback into the large scales. There has been a push to implement these methods in other parts of the Earth System and for the cryosphere in particular but in order to test these methods, efficient and accurate solvers are required for the resolved large scale sea-ice dynamics. We present a second order accurate scheme, in both time and space, for the sea ice momentum equation (SIME) with a Jacobian Free Newton Krylov (JFNK) solver. SIME is a highly nonlinear equation due to sea ice rheology terms appearing in the stress tensor. The most commonly accepted formulation, introduced by Hibler, allows sea-ice to resist significant stresses in compression but significantly less in tension. The relationship also leads to large changes in internal stresses from small changes in velocity fields. These non-linearities have resulted in the use of implicit methods for SIME and a JFNK solver was recently introduced and used to gain efficiency. However, the method used so far is only first order accurate in time. Here we expand the JFNK approach to a Crank-Nicholson discretization of SIME. This fully second order scheme is achieved with no increase in computational cost and will allow efficient testing and development of subgrid stochastic models of sea ice in the near future.

  1. A subgrid parameterization scheme for precipitation

    Directory of Open Access Journals (Sweden)

    S. Turner

    2012-04-01

    Full Text Available With increasing computing power, the horizontal resolution of numerical weather prediction (NWP models is improving and today reaches 1 to 5 km. Nevertheless, clouds and precipitation formation are still subgrid scale processes for most cloud types, such as cumulus and stratocumulus. Subgrid scale parameterizations for water vapor condensation have been in use for many years and are based on a prescribed probability density function (PDF of relative humidity spatial variability within the model grid box, thus providing a diagnosis of the cloud fraction. A similar scheme is developed and tested here. It is based on a prescribed PDF of cloud water variability and a threshold value of liquid water content for droplet collection to derive a rain fraction within the model grid. Precipitation of rainwater raises additional concerns relative to the overlap of cloud and rain fractions, however. The scheme is developed following an analysis of data collected during field campaigns in stratocumulus (DYCOMS-II and fair weather cumulus (RICO and tested in a 1-D framework against large eddy simulations of these observed cases. The new parameterization is then implemented in a 3-D NWP model with a horizontal resolution of 2.5 km to simulate real cases of precipitating cloud systems over France.

  2. The Sensitivity of Simulated Competition Between Different Plant Functional Types to Subgrid Scale Representation of Vegetation in a Land Surface Model

    Science.gov (United States)

    Shrestha, R. K.; Arora, V.; Melton, J. R.

    2014-12-01

    Vegetation is a dynamic component of the earth system that affects weather and climate at hourly to centennial time scales. However, most current dynamic vegetation models do not explicitly simulate competition among Plant Functional Types (PFTs). Here we use the coupled CLASS-CTEM model (Canadian Land Surface Scheme coupled to Canadian Terrestrial Ecosystem Model) to explicitly simulate competition between nine PFTs for available space using a modified version of Lotka - Volterra (LV) predator-prey equations. The nine PFTs include evergreen and deciduous needleleaf trees, evergreen and cold and drought deciduous broadleaf trees and C3 and C4 crops and grasses. The CLASS-CTEM model can be configured either in the composite (single tile) or the mosaic (multiple tiles) mode. Our results show that the model is sensitive to the chosen mode. The simulated fractional coverage of PFTs are similar between two approaches at some locations whereas at the other locations the two approaches yield different results. The simulated fractional coverage of PFTs are also compared with the available observations-based estimates. Simulated results at selected locations across the globe show that the model is able to realistically simulate the fractional coverage of tree and grass PFTs and the bare fraction, as well as the fractional coverage of individual tree and grass PFTs. Along with the observed patterns of vegetation distribution the CLASS-CTEM modelling framework is also able to simulate realistic succession patterns. Some differences remain and these are attributed to the coarse spatial resolution of the model (~3.75°) and the limited number of PFTs represented in the model.

  3. Subgrid Parameterization of the Soil Moisture Storage Capacity for a Distributed Rainfall-Runoff Model

    Directory of Open Access Journals (Sweden)

    Weijian Guo

    2015-05-01

    Full Text Available Spatial variability plays an important role in nonlinear hydrologic processes. Due to the limitation of computational efficiency and data resolution, subgrid variability is usually assumed to be uniform for most grid-based rainfall-runoff models, which leads to the scale-dependence of model performances. In this paper, the scale effect on the Grid-Xinanjiang model was examined. The bias of the estimation of precipitation, runoff, evapotranspiration and soil moisture at the different grid scales, along with the scale-dependence of the effective parameters, highlights the importance of well representing the subgrid variability. This paper presents a subgrid parameterization method to incorporate the subgrid variability of the soil storage capacity, which is a key variable that controls runoff generation and partitioning in the Grid-Xinanjiang model. In light of the similar spatial pattern and physical basis, the soil storage capacity is correlated with the topographic index, whose spatial distribution can more readily be measured. A beta distribution is introduced to represent the spatial distribution of the soil storage capacity within the grid. The results derived from the Yanduhe Basin show that the proposed subgrid parameterization method can effectively correct the watershed soil storage capacity curve. Compared to the original Grid-Xinanjiang model, the model performances are quite consistent at the different grid scales when the subgrid variability is incorporated. This subgrid parameterization method reduces the recalibration necessity when the Digital Elevation Model (DEM resolution is changed. Moreover, it improves the potential for the application of the distributed model in the ungauged basin.

  4. Subgrid Modeling Geomorphological and Ecological Processes in Salt Marsh Evolution

    Science.gov (United States)

    Shi, F.; Kirby, J. T., Jr.; Wu, G.; Abdolali, A.; Deb, M.

    2016-12-01

    Numerical modeling a long-term evolution of salt marshes is challenging because it requires an extensive use of computational resources. Due to the presence of narrow tidal creeks, variations of salt marsh topography can be significant over spatial length scales on the order of a meter. With growing availability of high-resolution bathymetry measurements, like LiDAR-derived DEM data, it is increasingly desirable to run a high-resolution model in a large domain and for a long period of time to get trends of sedimentation patterns, morphological change and marsh evolution. However, high spatial-resolution poses a big challenge in both computational time and memory storage, when simulating a salt marsh with dimensions of up to O(100 km^2) with a small time step. In this study, we have developed a so-called Pre-storage, Sub-grid Model (PSM, Wu et al., 2015) for simulating flooding and draining processes in salt marshes. The simulation of Brokenbridge salt marsh, Delaware, shows that, with the combination of the sub-grid model and the pre-storage method, over 2 orders of magnitude computational speed-up can be achieved with minimal loss of model accuracy. We recently extended PSM to include a sediment transport component and models for biomass growth and sedimentation in the sub-grid model framework. The sediment transport model is formulated based on a newly derived sub-grid sediment concentration equation following Defina's (2000) area-averaging procedure. Suspended sediment transport is modeled by the advection-diffusion equation in the coarse grid level, but the local erosion and sedimentation rates are integrated over the sub-grid level. The morphological model is based on the existing morphological model in NearCoM (Shi et al., 2013), extended to include organic production from the biomass model. The vegetation biomass is predicted by a simple logistic equation model proposed by Marani et al. (2010). The biomass component is loosely coupled with hydrodynamic and

  5. Criterion validation of a stress measure: the Stress Overload Scale.

    Science.gov (United States)

    Amirkhan, James H; Urizar, Guido G; Clark, Sarah

    2015-09-01

    Validating stress scales poses problems beyond those of other psychological measures. Here, 3 studies were conducted to address those problems and assess the criterion validity of scores from a new theory-derived measure, the Stress Overload Scale (SOS; Amirkhan, 2012). In Study 1, the SOS was tested for its ability to predict postsemester illness in a sample of college students (n = 127). Even with precautions to minimize criterion contamination, scores were found to predict health problems in the month following a final exam on all of 5 different criteria. In Study 2, a community sample (n = 231) was used to test the SOS' ability to differentiate people in stressful circumstances from those in more relaxed contexts. SOS scores demonstrated excellent sensitivity (96%) and specificity (100%) in this general population application. In Study 3, the SOS was tested for its ability to differentiate salivary cortisol responses to a laboratory stressor in a group of pregnant women (n = 40). High scores were found to be associated with a blunted cortisol response, which is indicative of HPA-axis overload and typical of persons suffering chronic stress and stress-related pathology. Across all 3 studies, despite variations in the stressor, criterion, population, and methods, SOS scores emerged as valid indicators of stress. However, each study also introduced new problems that beg additional corrective steps in future stress-scale validity tests. These strategies, and the SOS' utility as a research and diagnostic tool in varied applications and populations, are discussed. (c) 2015 APA, all rights reserved.

  6. Optimal scaling for early life stress measurement

    Directory of Open Access Journals (Sweden)

    Alexander Zvinchuk

    2013-06-01

    Full Text Available BACKGROUND: Early life stress is associated with high risk for both negative psychological and physical health outcomes. However, many of the stressful life events inventories that have been used in epidemiological research have not been validated or checked for reliability or consistency. The aim of our study is to use optimal scaling and correspondence analysis that employ categorical principal components analysis (CATPCA algorithm to consider the internal structure and the geometry of the space of variables obtained through the questions measuring early life stress. This approach was chosen because it allows quantification of categorical (both nominal and ordinal scales and reduction of initial number of variables with interval quantification of the resulting dimensions. METHODS: A questionnaire for measuring early life stress was applied to the participants of the Ukrainian component of European Longitudinal Study of Pregnancy and Childhood at the age of three and seven years. CATPCA algorithm was used to elaborate a tool for estimating related integral quantified characteristics.RESULTS: Application of quantification and dimension reduction techniques to the categorical variables measuring stress in three- and seven-year-old children resulted in two dimensions. The first dimension that accounts for a major part of initial variance and is associated with all the collected variables can be interpreted as the overall measure of stress. The second dimension accounts for smaller but still considerable part of variance and can be related to child’s attachment to mother and acquiring new experience as the route of development.CONCLUSIONS: Application of optimal scaling to the empirical data of early life stress measurement resulted in construction of two integral indicators – first measuring overall stress and second contrasting security related to child’s attachment to mother and new experiences – consistent across age groups of three and

  7. Psychometric Validation of Stress and Compliance Scale for ...

    African Journals Online (AJOL)

    Indonesia, 4Unit of Clinical Pharmacy & Pharmacy Practice, Dubai Pharmacy College, Dubai ... Keywords: Diabetes mellitus, Malaysia stress scale, Stress and compliance scale for diabetes, ..... counselors working with university students will.

  8. Analysis of subgrid models of heat convection by symmetry group theory

    Science.gov (United States)

    Razafindralandy, Dina; Hamdouni, Aziz

    2007-04-01

    Symmetries, i.e. transformations which leave the set of the solutions of the Navier-Stokes equations unchanged, play an important role in turbulence (conservation laws, wall laws, …). They should not be destroyed by turbulence models. The symmetries of the heat convection equations are then presented, for a non-isothermal fluid. Next, common subgrid stress tensor and flux models are analyzed, using the symmetry approach. To cite this article: D. Razafindralandy, A. Hamdouni, C. R. Mecanique 335 (2007).

  9. Stochastic representation of the Reynolds transport theorem: revisiting large-scale modeling

    CERN Document Server

    Harouna, S Kadri

    2016-01-01

    We explore the potential of a formulation of the Navier-Stokes equations incorporating a random description of the small-scale velocity component. This model, established from a version of the Reynolds transport theorem adapted to a stochastic representation of the flow, gives rise to a large-scale description of the flow dynamics in which emerges an anisotropic subgrid tensor, reminiscent to the Reynolds stress tensor, together with a drift correction due to an inhomogeneous turbulence. The corresponding subgrid model, which depends on the small scales velocity variance, generalizes the Boussinesq eddy viscosity assumption. However, it is not anymore obtained from an analogy with molecular dissipation but ensues rigorously from the random modeling of the flow. This principle allows us to propose several subgrid models defined directly on the resolved flow component. We assess and compare numerically those models on a standard Green-Taylor vortex flow at Reynolds 1600. The numerical simulations, carried out w...

  10. Monte Carlo-based subgrid parameterization of vertical velocity and stratiform cloud microphysics in ECHAM5.5-HAM2

    Directory of Open Access Journals (Sweden)

    J. Tonttila

    2013-08-01

    Full Text Available A new method for parameterizing the subgrid variations of vertical velocity and cloud droplet number concentration (CDNC is presented for general circulation models (GCMs. These parameterizations build on top of existing parameterizations that create stochastic subgrid cloud columns inside the GCM grid cells, which can be employed by the Monte Carlo independent column approximation approach for radiative transfer. The new model version adds a description for vertical velocity in individual subgrid columns, which can be used to compute cloud activation and the subgrid distribution of the number of cloud droplets explicitly. Autoconversion is also treated explicitly in the subcolumn space. This provides a consistent way of simulating the cloud radiative effects with two-moment cloud microphysical properties defined at subgrid scale. The primary impact of the new parameterizations is to decrease the CDNC over polluted continents, while over the oceans the impact is smaller. Moreover, the lower CDNC induces a stronger autoconversion of cloud water to rain. The strongest reduction in CDNC and cloud water content over the continental areas promotes weaker shortwave cloud radiative effects (SW CREs even after retuning the model. However, compared to the reference simulation, a slightly stronger SW CRE is seen e.g. over mid-latitude oceans, where CDNC remains similar to the reference simulation, and the in-cloud liquid water content is slightly increased after retuning the model.

  11. Unsteady Flame Embedding (UFE) Subgrid Model for Turbulent Premixed Combustion Simulations

    KAUST Repository

    El-Asrag, Hossam

    2010-01-04

    We present a formulation for an unsteady subgrid model for premixed combustion in the flamelet regime. Since chemistry occurs at the unresolvable scales, it is necessary to introduce a subgrid model that accounts for the multi-scale nature of the problem using the information available on the resolved scales. Most of the current models are based on the laminar flamelet concept, and often neglect the unsteady effects. The proposed model\\'s primary objective is to encompass many of the flame/turbulence interactions unsteady features and history effects. In addition it provides a dynamic and accurate approach for computing the subgrid flame propagation velocity. The unsteady flame embedding approach (UFE) treats the flame as an ensemble of locally one-dimensional flames. A set of elemental one dimensional flames is used to describe the turbulent flame structure at the subgrid level. The stretched flame calculations are performed on the stagnation line of a strained flame using the unsteady filtered strain rate computed from the resolved- grid. The flame iso-surface is tracked using an accurate high-order level set formulation to propagate the flame interface at the coarse resolution with minimum numerical diffusion. In this paper the solver and the model components are introduced and used to investigate two unsteady flames with different Lewis numbers in the thin reaction zone regime. The results show that the UFE model captures the unsteady flame-turbulence interactions and the flame propagation speed reasonably well. Higher propagation speed is observed for the lower than unity Lewis number flame because of the impact of differential diffusion.

  12. Discontinuous Galerkin Subgrid Finite Element Method for Heterogeneous Brinkman’s Equations

    KAUST Repository

    Iliev, Oleg P.

    2010-01-01

    We present a two-scale finite element method for solving Brinkman\\'s equations with piece-wise constant coefficients. This system of equations model fluid flows in highly porous, heterogeneous media with complex topology of the heterogeneities. We make use of the recently proposed discontinuous Galerkin FEM for Stokes equations by Wang and Ye in [12] and the concept of subgrid approximation developed for Darcy\\'s equations by Arbogast in [4]. In order to reduce the error along the coarse-grid interfaces we have added a alternating Schwarz iteration using patches around the coarse-grid boundaries. We have implemented the subgrid method using Deal.II FEM library, [7], and we present the computational results for a number of model problems. © 2010 Springer-Verlag Berlin Heidelberg.

  13. [Nursery Teacher's Stress Scale (NTSS): reliability and validity].

    Science.gov (United States)

    Akada, Taro

    2010-06-01

    This study describes the development and evaluation of the Nursery Teacher's Stress Scale (NTSS), which explores the relation between daily hassles at work and work-related stress. In Analysis 1, 29 items were chosen to construct the NTSS. Six factors were identified: I. Stress relating to child care; II. Stress from human relations at work; III. Stress from staff-parent relations; IV. Stress from lack of time; V. Stress relating to compensation; and VI. Stress from the difference between individual beliefs and school policy. All these factors had high degrees of internal consistency. In Analysis 2, the concurrent validity of the NTSS was examined. The results showed that the NTSS total scores were significantly correlated with the Job Stress Scale-Revised Version (job stressor scale, r = .68), the Pre-school Teacher-efficacy Scale (r = -.21), and the WHO-five Well-Being Index Japanese Version (r = -.40). Work stresses are affected by several daily hassles at work. The NTSS has acceptable reliability and validity, and can be used to improve nursery teacher's mental health.

  14. A new downscaling method for sub-grid turbulence modeling

    Directory of Open Access Journals (Sweden)

    L. Rottner

    2017-06-01

    Full Text Available In this study we explore a new way to model sub-grid turbulence using particle systems. The ability of particle systems to model small-scale turbulence is evaluated using high-resolution numerical simulations. These high-resolution data are averaged to produce a coarse-grid velocity field, which is then used to drive a complete particle-system-based downscaling. Wind fluctuations and turbulent kinetic energy are compared between the particle simulations and the high-resolution simulation. Despite the simplicity of the physical model used to drive the particles, the results show that the particle system is able to represent the average field. It is shown that this system is able to reproduce much finer turbulent structures than the numerical high-resolution simulations. In addition, this study provides an estimate of the effective spatial and temporal resolution of the numerical models. This highlights the need for higher-resolution simulations in order to evaluate the very fine turbulent structures predicted by the particle systems. Finally, a study of the influence of the forcing scale on the particle system is presented.

  15. Development and preliminary validation of the Salzburg Stress Eating Scale.

    Science.gov (United States)

    Meule, Adrian; Reichenberger, Julia; Blechert, Jens

    2018-01-01

    Stress-related eating has long been a focus of study in several disciplines. Currently available psychometric scales conflate stress-related eating with emotional eating despite that not all stress states can be subsumed under some form of specific emotion. Moreover, existing measures primarily assess increased food intake in response to emotions and stress, thus ignoring evidence of decreased food intake in response to stress. Therefore, we drew from established stress concepts to develop the first genuine stress-related eating scale (Salzburg Stress Eating Scale [SSES]) in both German and English versions. In the SSES higher scores indicate eating more when stressed and lower scores indicate eating less when stressed. In study 1 (n = 340), the German SSES was found to have a one-factor structure (α = 0.89). SSES scores were weakly or moderately correlated with other eating-related constructs (e.g., emotional eating, body mass index [BMI]), and weakly correlated or uncorrelated with non-eating-related constructs (e.g., impulsivity, perceived stress); in addition, women had higher scores than men. Perceived stress moderated the association between stress eating and BMI, such that higher SSES scores were significantly related to higher BMI in individuals with high perceived stress, but not in individuals with low perceived stress. In studies 2 (n = 790) and 3 (n = 331), factor structure, internal consistency, and associations with sex and BMI were replicated for both German and English versions of the SSES. Hence, the SSES represents a psychometrically sound tool for the measurement of stress-related eating. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Validation of Bengali perceived stress scale among LGBT population

    OpenAIRE

    Mozumder, Muhammad Kamruzzaman

    2017-01-01

    Background Lesbian, gay, bisexual and transgender (LGBT) population encounter more stressful life circumstances compared to general population. Perceived Stress Scale (PSS) can be a useful tool for measuring their stress. However, psychometric properties of PSS have never been tested on LGBT population. Methods This cross sectional study employed a two-stage sampling strategy to collect data from 296 LGBT participants from six divisional districts of Bangladesh. Exploratory (EFA) and confirma...

  17. Review of the Psychometric Evidence of the Perceived Stress Scale

    National Research Council Canada - National Science Library

    Lee, Eun-Hyun

    2012-01-01

    ... ( Cohen & Kessler, 1997 ; Kopp et al., 2010 ). The Perceived Stress Scale (PSS; Cohen, Kamarch, & Mermelstein, 1983 ) is one of the more popular tools for measuring psychological stress. It is a self-reported questionnaire that was designed to measure "the degree to which individuals appraise situations in their lives as stressfu...

  18. Construction of the Examination Stress Scale for Adolescent Students

    Science.gov (United States)

    Sung, Yao-Ting; Chao, Tzu-Yang

    2015-01-01

    The tools used for measuring examination stress have three main limitations: sample selected, sample sizes, and measurement contents. In this study, we constructed the Examination Stress Scale (ExamSS), and 4,717 high school students participated in this research. The results indicate that ExamSS has satisfactory reliability, construct validity,…

  19. Development of a stress scale for pregnant women in the South Asian context: the A-Z Stress Scale.

    Science.gov (United States)

    Kazi, A; Fatmi, Z; Hatcher, J; Niaz, U; Aziz, A

    2009-01-01

    Stress in pregnancy can lead to low-birth-weight and preterm babies and to psychological consequences such as anxiety and depression during pregnancy and the puerperium. Previous scales to measure stress contain items that overlap with the symptoms of pregnancy. A stress scale was developed based on in-depth interviews with pregnant women in Pakistan. Construct validity, test-retest reliability and inter-rater reliability were carried out. Cronbach alpha was 0.82 for the 30 short-listed items, with item-total correlations of 0.2-0.8. Multidimensional scaling determined 2 dimensions: socioenvironmental hassles and chronic illnesses. This was the first scale developed for pregnant women based on stressors in a developing country in South Asia.

  20. Development of the Abbreviated Masculine Gender Role Stress Scale.

    Science.gov (United States)

    Swartout, Kevin M; Parrott, Dominic J; Cohn, Amy M; Hagman, Brett T; Gallagher, Kathryn E

    2015-06-01

    Data gathered from 6 independent samples (n = 1,729) that assessed men's masculine gender role stress in college and community males were aggregated used to determine the reliability and validity of an abbreviated version of the Masculine Gender Role Stress (MGRS) Scale. The 15 items with the highest item-to-total scale correlations were used to create an abbreviated MGRS Scale. Psychometric properties of each of the 15 items were examined with item response theory (IRT) analysis, using the discrimination and threshold parameters. IRT results showed that the abbreviated scale may hold promise at capturing the same amount of information as the full 40-item scale. Relative to the 40-item scale, the total score of the abbreviated MGRS Scale demonstrated comparable convergent validity using the measurement domains of masculine identity, hypermasculinity, trait anger, anger expression, and alcohol involvement. An abbreviated MGRS Scale may be recommended for use in clinical practice and research settings to reduce cost, time, and patient/participant burden. Additionally, IRT analyses identified items with higher discrimination and threshold parameters that may be used to screen for problematic gender role stress in men who may be seen in routine clinical or medical practice. (c) 2015 APA, all rights reserved).

  1. Fundamental Enabling Issues in Nanotechnology: Stress at the Atomic Scale

    Energy Technology Data Exchange (ETDEWEB)

    Floro, Jerrold Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science and Engineering; Foiles, Stephen Martin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hearne, Sean Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hoyt, Jeffrey John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McMaster Univ., Hamilton, ON (Canada); Seel, Steven Craig [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Emcore Corporation, Albuquerque, NM (United States); Webb, Edmund Blackburn [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Morales, Alfredo Martin [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Zimmerman, Jonathan A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2007-10-01

    To effectively integrate nanotechnology into functional devices, fundamental aspects of material behavior at the nanometer scale must be understood. Stresses generated during thin film growth strongly influence component lifetime and performance; stress has also been proposed as a mechanism for stabilizing supported nanoscale structures. Yet the intrinsic connections between the evolving morphology of supported nanostructures and stress generation are still a matter of debate. This report presents results from a combined experiment and modeling approach to study stress evolution during thin film growth. Fully atomistic simulations are presented predicting stress generation mechanisms and magnitudes during all growth stages, from island nucleation to coalescence and film thickening. Simulations are validated by electrodeposition growth experiments, which establish the dependence of microstructure and growth stresses on process conditions and deposition geometry. Sandia is one of the few facilities with the resources to combine experiments and modeling/theory in this close a fashion. Experiments predicted an ongoing coalescence process that generates signficant tensile stress. Data from deposition experiments also support the existence of a kinetically limited compressive stress generation mechanism. Atomistic simulations explored island coalescence and deposition onto surfaces intersected by grain boundary structures to permit investigation of stress evolution during later growth stages, e.g., continual island coalescence and adatom incorporation into grain boundaries. The predictive capabilities of simulation permit direct determination of fundamental processes active in stress generation at the nanometer scale while connecting those processes, via new theory, to continuum models for much larger island and film structures. Our combined experiment and simulation results reveal the necessary materials science to tailor stress, and therefore performance, in

  2. Perceived Stress Scale: Reliability and Validity Study in Greece

    Directory of Open Access Journals (Sweden)

    Eleni Andreou

    2011-08-01

    Full Text Available Objective: To translate the Perceived Stress Scale (versions PSS-4, -10 and -14 and to assess its psychometric properties in a sample of general Greek population. Methods: 941 individuals completed anonymously questionnaires comprising of PSS, the Depression Anxiety and Stress scale (DASS-21 version, and a list of stress-related symptoms. Psychometric properties of PSS were investigated by confirmatory factor analysis (construct validity, Cronbach’s alpha (reliability, and by investigating relations with the DASS-21 scores and the number of symptoms, across individuals’ characteristics. The two-factor structure of PSS-10 and PSS-14 was confirmed in our analysis. We found satisfactory Cronbach’s alpha values (0.82 for the full scale for PSS-14 and PSS-10 and marginal satisfactory values for PSS-4 (0.69. PSS score exhibited high correlation coefficients with DASS-21 subscales scores, meaning stress (r = 0.64, depression (r = 0.61, and anxiety (r = 0.54. Women reported significantly more stress compared to men and divorced or widows compared to married or singled only. A strong significant (p < 0.001 positive correlation between the stress score and the number of self-reported symptoms was also noted. Conclusions: The Greek versions of the PSS-14 and PSS-10 exhibited satisfactory psychometric properties and their use for research and health care practice is warranted.

  3. A distributed Grid-Xinanjiang model with integration of subgrid variability of soil storage capacity

    Directory of Open Access Journals (Sweden)

    Wei-jian Guo

    2016-04-01

    Full Text Available Realistic hydrological response is sensitive to the spatial variability of landscape properties. For a grid-based distributed rainfall-runoff model with a hypothesis of a uniform grid, the high-frequency information within a grid cell will be gradually lost as the resolution of the digital elevation model (DEM grows coarser. Therefore, the performance of a hydrological model is usually scale-dependent. This study used the Grid-Xinanjiang (GXAJ model as an example to investigate the effects of subgrid variability on hydrological response at different scales. With the aim of producing a more reasonable hydrological response and spatial description of the landscape properties, a new distributed rainfall-runoff model integrating the subgrid variability (the GXAJSV model was developed. In this model, the topographic index is used as an auxiliary variable correlated with the soil storage capacity. The incomplete beta distribution is suggested for simulating the probability distribution of the soil storage capacity within the raster grid. The Yaogu Basin in China was selected for model calibration and validation at different spatial scales. Results demonstrated that the proposed model can effectively eliminate the scale dependence of the GXAJ model and produce a more reasonable hydrological response.

  4. Validity of occupational stress assessment using a visual analogue scale.

    Science.gov (United States)

    Lesage, F X; Berjot, S

    2011-09-01

    The visual analogue scale (VAS) is empirically used by occupational physicians to assess stress but very few studies have been published about its quantitative validation. To assess the external validity of the VAS for the assessment of stress in the clinical occupational health setting by comparing its scores with the Perceived Stress Scale (PSS) of Cohen. An anonymous self-completed questionnaire (PSS14) and the VAS were filled in by a random sample of 360 workers from several occupational health centres. No difference between the mean scores of PSS14 and stress VAS was found. The equation of the linear regression was 'VAS score = -0.18 + 1008 × PSS14 score'. A VAS score of 7.0 was identified as having the best sensitivity/specificity ratio (0.74 and 0.93, respectively) for identifying those with 'high stress' using the PSS cut-off score of 7.2, using a receiver operator curve approach. Our results support an acceptable agreement between the two tests, meaning that the two tools assess the same psychological construct. The good sensitivity/specificity ratio and the area under the curve close to 1 provide evidence that a VAS is suitable to help the occupational physician detect a high level of stress. The use of a VAS for stress assessment seems to be meaningful, suitable and useful for occupational physicians.

  5. Measuring reliability and validity of a newly developed stress instrument: Newly Diagnosed Breast Cancer Stress Scale.

    Science.gov (United States)

    Lee, Tso-Ying; Chen, Hsing-Hsia; Yeh, Mei-Ling; Li, Hui-Ling; Chou, Kuei-Ru

    2013-09-01

    To assess the reliability and validity of a developed instrument entitled Newly Diagnosed Breast Cancer Stress Scale. Distress, clinical anxiety and depression are evident in patients with cancer, leading to poor psychosocial and quality-of-life outcomes. Instrument development study with norm-referenced measurements. Content validity was determined by expert review. Cronbach's α was used to assess internal consistency reliability and product-moment correlations were conducted. Exploratory factor analysis measured validity of items using varimax rotation method. Criterion-related validity testing used the Perceived Stress Scale and the convergent validity test of construct validity used the Hospital Anxiety and Depression Scale. A total of 125 women pathologically diagnosed with breast cancer were interviewed on the day prior to initial breast surgery. After testing, the Newly Diagnosed Breast Cancer Stress Scale consisted of four main factors with 17 items with acceptable reliability and good validity, and its length and time to complete the questionnaire were appropriate. Internal consistency reliability of the scale was shown by Cronbach's α = 0·84, the criterion validity of Perceived Stress Scale-10 was r = 0·46 (p validity of Hospital Anxiety and Depression Scale-14 was r = 0·57 (p validity to measure stress in newly diagnosed patients with breast cancer. The Newly Diagnosed Breast Cancer Stress Scale can provide healthcare workers with an instrument to better identify stress levels in newly diagnosed breast cancer patients and provide valuable information when defining psychosocial care interventions. © 2013 Blackwell Publishing Ltd.

  6. Clinical stress assessment using a visual analogue scale.

    Science.gov (United States)

    Lesage, F-X; Berjot, S; Deschamps, F

    2012-12-01

    Clinicians increasingly require short, efficient methods for assessing distress, both in applied research and clinical settings. Most of the available questionnaires are unsuitable for busy clinical settings. The visual analogue scale (VAS) is widely but empirically used to assess perceived stress. To provide evidence on two of the psychometric properties of the VAS: its discriminative sensitivity (capacity to highlight a difference between groups) and its interconcept validity (the relationship between VAS stress assessment and the assessment of different, but similar concepts). Employees attending occupational health centres were randomly selected and completed the VAS and also either the Perceived Stress Scale (PSS) or the Hospital Anxiety and Depression Scale (HADS). Analyses of variance were performed to study group effects (age, sex, marital status, parental status, occupational status) on stress scores (PSS and VAS). In total, 763 employees participated of whom 501 completed the PSS and 262 the HADS. P-values obtained for the effects of sex, age and occupational status were lower with the VAS than with the PSS. Correlations between the VAS and the anxiety subscale, depression subscale and total score of the HADS were 0.66, 0.45 and 0.65, respectively. Other tools used to assess aspects of psychological distress are known to have similar correlations. Our findings provide evidence that the VAS is at least as discriminating as a questionnaire when it comes to highlighting differences in stress levels between two groups, and the observed correlations with related constructs support its construct validity.

  7. Development and validation of academic stress scale among ...

    African Journals Online (AJOL)

    The objective of this study was to develop and measure the psychometric properties of Academic Stress Scale among undergraduates in the South-West, Nigeria. The study adopted a cross-sectional survey research design. The participants in the study were 453 (Male =232; Female = 221) undergraduates selected from ...

  8. Psychometric Validation of Stress and Compliance Scale for ...

    African Journals Online (AJOL)

    Psychometric Validation of Stress and Compliance Scale for Diabetes (SCSD) in Penang, Malaysia. S Wasif Gillani1*, Syed Azhar Syed S2, Diana Laila Rahmatillah3 and Mirza Baig4. 1School of Pharmacy, Monash University Sunway Campus, 47500, Bandar Sunway, Selangor, 2Discipline of Clinical Pharmacy,. School of ...

  9. Combination of Lidar Elevations, Bathymetric Data, and Urban Infrastructure in a Sub-Grid Model for Predicting Inundation in New York City during Hurricane Sandy

    CERN Document Server

    Loftis, Jon Derek; Hamilton, Stuart E; Forrest, David R

    2014-01-01

    We present the geospatial methods in conjunction with results of a newly developed storm surge and sub-grid inundation model which was applied in New York City during Hurricane Sandy in 2012. Sub-grid modeling takes a novel approach for partial wetting and drying within grid cells, eschewing the conventional hydrodynamic modeling method by nesting a sub-grid containing high-resolution lidar topography and fine scale bathymetry within each computational grid cell. In doing so, the sub-grid modeling method is heavily dependent on building and street configuration provided by the DEM. The results of spatial comparisons between the sub-grid model and FEMA's maximum inundation extents in New York City yielded an unparalleled absolute mean distance difference of 38m and an average of 75% areal spatial match. An in-depth error analysis reveals that the modeled extent contour is well correlated with the FEMA extent contour in most areas, except in several distinct areas where differences in special features cause sig...

  10. Stress and depression scales in aphasia: relation between the aphasia depression rating scale, stroke aphasia depression questionnaire-10, and the perceived stress scale.

    Science.gov (United States)

    Laures-Gore, Jacqueline S; Farina, Matthew; Moore, Elliot; Russell, Scott

    2017-03-01

    Assessment and diagnosis of post-stroke depression (PSD) among patients with aphasia presents unique challenges. A gold standard assessment of PSD among this population has yet to be identified. The first aim was to investigate the association between two depression scales developed for assessing depressive symptoms among patients with aphasia. The second aim was to evaluate the relation between these scales and a measure of perceived stress. Twenty-five (16 male; 9 female) individuals with history of left hemisphere cerebrovascular accident (CVA) were assessed for depression and perceived stress using the Stroke Aphasic Depression Questionnaire-10 (SADQ-10), the Aphasia Depression Rating Scale (ADRS), and the Perceived Stress Scale (PSS). SADQ-10 and ADRS ratings were strongly correlated with each other (r = 0.708, p perceived stress may also be an important factor in assessment of depressive symptoms.

  11. [Spanish adaptation of the Stress Manifestations Scale of the Student Stress Inventory (SSI-SM)].

    Science.gov (United States)

    Escobar Espejo, Milagros; Blanca, María J; Fernández-Baena, F Javier; Trianes Torres, María Victoria

    2011-08-01

    The aim of the present study was to translate into Spanish and to describe the psychometric properties of the Stress Manifestations Scale of the Student Stress Inventory (SSI-SM), developed by Fimian, Fastenau, Tashner and Cross to identify the main manifestations of stress in adolescents. The scale was applied to a sample of 1,002 pupils from years one and two of Secondary Education. The paper reports the factor structure, an item analysis, the internal consistency, differences by sex and academic year, external evidence of validity, and norms for scoring the scale. The results reveal a factor structure based on three first-order factors (emotional manifestations, physiological manifestations and behavioural manifestations) and one second-order factor (indicative of stress manifestations). In terms of external validity, there was a positive association with measures of perceived stress, aggressiveness, internalized/externalized symptoms, and a negative association with life satisfaction. The results show that the scale is an adequate tool for evaluating stress manifestations in adolescents.

  12. Acceleration of inertial particles in wall bounded flows: DNS and LES with stochastic modelling of the subgrid acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Zamansky, Remi; Vinkovic, Ivana; Gorokhovski, Mikhael, E-mail: ivana.vinkovic@univ-lyonl.fr [Laboratoire de Mecanique des Fluides et d' Acoustique CNRS UMR 5509 Ecole Centrale de Lyon, 36, av. Guy de Collongue, 69134 Ecully Cedex (France)

    2011-12-22

    Inertial particle acceleration statistics are analyzed using DNS for turbulent channel flow. Along with effects recognized in homogeneous isotropic turbulence, an additional effect is observed due to high and low speed vortical structures aligned with the channel wall. In response to those structures, particles with moderate inertia experience strong longitudinal acceleration variations. DNS is also used in order to assess LES-SSAM (Subgrid Stochastic Acceleration Model), in which an approximation to the instantaneous non-filtered velocity field is given by simulation of both, filtered and residual, accelerations. This approach allow to have access to the intermittency of the flow at subgrid scale. Advantages of LES-SSAM in predicting particle dynamics in the channel flow at a high Reynolds number are shown.

  13. Autonomous Operation of Hybrid Microgrid With AC and DC Subgrids

    DEFF Research Database (Denmark)

    Chiang Loh, Poh; Li, Ding; Kang Chai, Yi

    2013-01-01

    This paper investigates on power-sharing issues of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac subgrids interconnected by power electronic interfaces. The main challenge here is to manage power flows among all...... converters. Suitable control and normalization schemes are now developed for controlling them with the overall hybrid microgrid performance already verified in simulation and experiment....

  14. Operational forecasting with the subgrid technique on the Elbe Estuary

    Science.gov (United States)

    Sehili, Aissa

    2017-04-01

    Modern remote sensing technologies can deliver very detailed land surface height data that should be considered for more accurate simulations. In that case, and even if some compromise is made with regard to grid resolution of an unstructured grid, simulations still will require large grids which can be computationally very demanding. The subgrid technique, first published by Casulli (2009), is based on the idea of making use of the available detailed subgrid bathymetric information while performing computations on relatively coarse grids permitting large time steps. Consequently, accuracy and efficiency are drastically enhanced if compared to the classical linear method, where the underlying bathymetry is solely discretized by the computational grid. The algorithm guarantees rigorous mass conservation and nonnegative water depths for any time step size. Computational grid-cells are permitted to be wet, partially wet or dry and no drying threshold is needed. The subgrid technique is used in an operational forecast model for water level, current velocity, salinity and temperature of the Elbe estuary in Germany. Comparison is performed with the comparatively highly resolved classical unstructured grid model UnTRIM. The daily meteorological forcing data are delivered by the German Weather Service (DWD) using the ICON-EU model. Open boundary data are delivered by the coastal model BSHcmod of the German Federal Maritime and Hydrographic Agency (BSH). Comparison of predicted water levels between classical and subgrid model shows a very good agreement. The speedup in computational performance due to the use of the subgrid technique is about a factor of 20. A typical daily forecast can be carried out within less than 10 minutes on standard PC-like hardware. The model is capable of permanently delivering highly resolved temporal and spatial information on water level, current velocity, salinity and temperature for the whole estuary. The model offers also the possibility to

  15. Chemical sensing of plant stress at the ecosystem scale

    Directory of Open Access Journals (Sweden)

    T. Karl

    2008-09-01

    Full Text Available Significant ecosystem-scale emissions of methylsalicylate (MeSA, a semivolatile plant hormone thought to act as the mobile signal for systemic acquired resistance (SAR, were observed in an agroforest. Our measurements show that plant internal defence mechanisms can be activated in response to temperature stress and are modulated by water availability on large scales. Highest MeSA fluxes (up to 0.25 mg/m2/h were observed after plants experienced ambient night-time temperatures of ~7.5°C followed by a large daytime temperature increase (e.g. up to 22°C. Under these conditions estimated night-time leaf temperatures were as low as ~4.6°C, likely inducing a response to prevent chilling injury. Our observations imply that plant hormones can be a significant component of ecosystem scale volatile organic compound (VOC fluxes (e.g. as high as the total monoterpene (MT flux and therefore contribute to the missing VOC budget. If generalized to other ecosystems and different types of stresses these findings suggest that semivolatile plant hormones have been overlooked by investigations of the impact of biogenic VOCs on aerosol formation events in forested regions. Our observations show that the presence of MeSA in canopy air serves as an early chemical warning signal indicating ecosystem-scale stresses before visible damage becomes apparent. As a chemical metric, ecosystem emission measurements of MeSA in ambient air could therefore support field studies investigating factors that adversely affect plant growth.

  16. Water stress strengthens mutualism among ants, trees, and scale insects.

    Science.gov (United States)

    Pringle, Elizabeth G; Akçay, Erol; Raab, Ted K; Dirzo, Rodolfo; Gordon, Deborah M

    2013-11-01

    Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant-plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant-plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.

  17. Water stress strengthens mutualism among ants, trees, and scale insects.

    Directory of Open Access Journals (Sweden)

    Elizabeth G Pringle

    2013-11-01

    Full Text Available Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant-plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant-plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.

  18. Validation of Bengali perceived stress scale among LGBT population.

    Science.gov (United States)

    Mozumder, Muhammad Kamruzzaman

    2017-08-29

    Lesbian, gay, bisexual and transgender (LGBT) population encounter more stressful life circumstances compared to general population. Perceived Stress Scale (PSS) can be a useful tool for measuring their stress. However, psychometric properties of PSS have never been tested on LGBT population. This cross sectional study employed a two-stage sampling strategy to collect data from 296 LGBT participants from six divisional districts of Bangladesh. Exploratory (EFA) and confirmatory factor analysis (CFA) were carried out on PSS 10 along with analysis of reliability and validity. EFA revealed a two-factor structure of PSS for LGBT population explaining 43.55% - 51.45% of total variance. This measurement model was supported by multiple fit indices during CFA. Acceptable Cronbach's alpha indicated internal consistency reliability and high correlations with Self Reporting Questionnaire 20 demonstrated construct validity of PSS 10 for LGBT population. This study provided evidence of satisfactory psychometric properties of Bengali PSS 10 in terms of factor structure, internal consistency and validity among LGBT population.

  19. The construct validity of the Perceived Stress Scale.

    Science.gov (United States)

    Nielsen, Marie Germund; Ørnbøl, Eva; Vestergaard, Mogens; Bech, Per; Larsen, Finn Breinholt; Lasgaard, Mathias; Christensen, Kaj Sparle

    2016-05-01

    Stress impacts the quality of life and is associated with increased risk of mental and physical disorders. The Perceived Stress Scale (PSS) is widely used for measuring psychological distress. Although the instrument was originally defined as a single construct, several studies based on classical test theory suggest that a two-dimensional structure is more dominant. We aimed to explore the construct validity and dimensionality of the PSS-10 using modern test theory to determine if the scale is predominantly for a one- or a two-dimensional model. The study population consisted of 32,374 citizens who completed the PSS-10 as part of the Danish National Health Survey in 2010. We investigated the construct validity of the PSS-10 by CFA. We examined the scalability by investigating the fit of the data distribution in a unidimensional Rasch model and performing modification of response categories, persons and items. The scale dimensionality was additionally assessed by Mokken and Rasch analysis. The PSS-10 did not fit the Rasch model. Item four indicated the largest misfit, and items four and seven displayed disordered thresholds. Unidimensionality could not be established although the data showed improved fit to the Rasch model for the two dimensions respectively with the positive and negative items. Mokken analysis revealed fit to the unidimensional model, but disordered thresholds were shown for item four. Our large population-based study indicated scalability problems in the current version of the PSS-10. The conducted analysis overall revealed better statistical fit for a two-dimensional than a unidimensional model. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. On the development of a subgrid CFD model for fire extinguishment

    Energy Technology Data Exchange (ETDEWEB)

    TIESZEN,SHELDON R.; LOPEZ,AMALIA R.

    2000-02-02

    A subgrid model is presented for use in CFD fire simulations to account for thermal suppressants and strain. The extinguishment criteria is based on the ratio of a local fluid-mechanics time-scale to a local chemical time-scale compared to an empirically-determined critical Damkohler number. Local extinction occurs if this time scale is exceeded, global fire extinguishment occurs when local extinction has occurred for all combusting cells. The fluid mechanics time scale is based on the Kolmogorov time scale and the chemical time scale is based on blowout of a perfectly stirred reactor. The input to the reactor is based on cell averaged temperatures, assumed stoichiometric fuel/air composition, and cell averaged suppressant concentrations including combustion products. A detailed chemical mechanism is employed. The chemical time-scale is precalculated and mixing rules are used to reduce the composition space that must be parameterized. Comparisons with experimental data for fire extinguishment in a flame-stabilizing, backward-facing step geometry indicates that the model is conservative for this condition.

  1. An Arabic version of the perceived stress scale: translation and validation study.

    Science.gov (United States)

    Almadi, Tawfiq; Cathers, Ian; Hamdan Mansour, Ayman M; Chow, Chin Moi

    2012-01-01

    The Perceived Stress Scale has been designed to measure the degree to which situations in a person's life are perceived as stressful. The paper describes the development of an Arabic version of the Perceived Stress Scale. A translation process with cross-cultural considerations was employed to produce an Arabic version of the Perceived Stress Scale. Participants were asked to complete the Arabic version Perceived Stress Scale twice in their homes. The Jordanian study population for the Arabic version Perceived Stress Scale validation consisted of 126 volunteers (74 male, 52 female). Ninety participants completed the scale twice (55 male, 35 female), of whom 58 were high schools teachers and 32 technical workers. Arabic was the first language of all participants and all gave informed consent. The Arabic version Perceived Stress Scale reliability and validity were evaluated. Prior to an exploratory factor analysis, the suitability of data for factor analysis was assessed with acceptable results. The exploratory factor analysis showed two factors with eigenvalues greater than 1.0 (45.0% of variance). The Cronbach's alpha coefficients were 0.74 (Factor 1), 0.77 (Factor 2) and 0.80 for the Arabic version Perceived Stress Scale overall. The test-retest reliability had an intra-correlation coefficient of 0.90. The Arabic version Perceived Stress Scale showed an adequate reliability and validity. Therefore, the Arabic Perceived Stress Scale is considered a suitable instrument to assess perceived stress in Arabic people. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Development and validation of the medical student stress scale in Korea.

    Science.gov (United States)

    Kim, Min Jeong; Park, Kwi Hwa; Yoo, Hyo Hyun; Park, Ie Byung; Yim, Jun

    2014-09-01

    Medical students experience various stresses that arise in a special environment. However, there is no specific stress scale for medical students with regard to their environment in Korea. Therefore, in this study, we developed and confirmed the validity of a stress scale for medical students in Korea. A draft version of the scale was developed on the basis of open-ended questionnaires from 97 medical students. The validity of the content of this scale was evaluated by three medical educationists. The scale was administered to 435 third and fourth grade medical students as the main survey. For our data, we performed an exploratory factor analysis and confirmatory factor analysis. We used Cronbach α index to determine internal consistency. Six factors with 40 items were extracted through the exploratory factor analysis: academic stress (9 items); clerkship stress (11 items); interpersonal stress (7 items); career stress (8 items); health-related stress (3 items); and financial stress (2 items). These factors showed a statistically significant correlation. The confirmatory factor analysis demonstrated a favorable RMSEA (0.053) and reasonable fit (CFI=0.847, TLI=0.833). Cronbach α values of the six factors ranged from 0.63 to 0.85. The medical student stress scale had a good model fit. It is a valid and reliable instrument in identifying stress in medical students and can be used in future studies. Also, the scale is expected to provide individual stress profiles for students to help them manage stress more effectively.

  3. Cross-cultural validity of the masculine and Feminine Gender Role Stress scales

    NARCIS (Netherlands)

    van Well, S; Kolk, AM; Arrindell, WA

    The objective was to examine the usefulness of Dutch versions of the Masculine Gender Role Stress (MGRS; Eisler & Skidmore, 1987) Scale and the Feminine Gender Role Stress (Gillespie & Eisler, 1992) Scale in The Netherlands. Undergraduate students (N = 2,239) completed both gender role stress

  4. The Perceived Stress Reactivity Scale: Measurement Invariance, Stability, and Validity in Three Countries

    Science.gov (United States)

    Schlotz, Wolff; Yim, Ilona S.; Zoccola, Peggy M.; Jansen, Lars; Schulz, Peter

    2011-01-01

    There is accumulating evidence that individual differences in stress reactivity contribute to the risk for stress-related disease. However, the assessment of stress reactivity remains challenging, and there is a relative lack of questionnaires reliably assessing this construct. We here present the Perceived Stress Reactivity Scale (PSRS), a…

  5. Workplace stress in nursing workers from an emergency hospital: Job Stress Scale analysis.

    Science.gov (United States)

    Urbanetto, Janete de Souza; da Silva, Priscila Costa; Hoffmeister, Eveline; de Negri, Bianca Souza; da Costa, Bartira Ercília Pinheiro; Poli de Figueiredo, Carlos Eduardo

    2011-01-01

    This study identifies workplace stress according to the Job Stress Scale and associates it with socio-demographic and occupational variables of nursing workers from an emergency hospital. This is a cross-sectional study and data were collected through a questionnaire applied to 388 nursing professionals. Descriptive statistics were applied; univariate and multivariate analyses were performed. The results indicate there is a significant association with being a nursing technician or auxiliary, working in the position for more than 15 years, and having low social support, with 3.84, 2.25 and 4.79 times more chances of being placed in the 'high strain job' quadrant. The study reveals that aspects related to the workplace should be monitored by competent agencies in order to improve the quality of life of nursing workers.

  6. A literature review of the application of the Geriatric Depression Scale, Depression Anxiety Stress Scales and Post-traumatic Stress Disorder Checklist to community nursing cohorts.

    Science.gov (United States)

    Allen, Jacqui; Annells, Merilyn

    2009-04-01

    To explore through literature review the appropriateness of three common tools for use by community nurses to screen war veteran and war widow(er) clients for depression, anxiety and post-traumatic stress disorder. War veterans and, to a lesser extent, war widow(er)s, are prone to mental health challenges, especially depression, anxiety and post-traumatic stress disorder. Community nurses do not accurately identify such people with depression and related disorders although they are well positioned to do so. The use of valid and reliable self-report tools is one method of improving nurses' identification of people with actual or potential mental health difficulties for referral to a general practitioner or mental health practitioner for diagnostic assessment and treatment. The Geriatric Depression Scale, Depression Anxiety Stress Scales and Post-traumatic Stress Disorder Checklist are frequently recommended for mental health screening but the appropriateness of using the tools for screening war veteran and war widow(er) community nursing clients who are often aged and have functional impairment, is unknown. Systematic review. Current literature informs that the Geriatric Depression Scale accurately predicts a diagnosis of depression in community nursing cohorts. The three Depression Anxiety Stress Scales subscales of depression, anxiety and stress are valid; however, no studies were identified that compared the performance of the Depression Anxiety Stress Scales in predicting diagnoses of depression or anxiety. The Post-traumatic Stress Disorder Checklist predicts post-traumatic stress disorder in community cohorts although no studies meeting the selection criteria included male participants. This review provides recommendations for the use of the Geriatric Depression Scale, Depression Anxiety Stress Scales and The Post-traumatic Stress Disorder Checklist based on examination of the published evidence for the application of these screening tools in samples

  7. Stress-induced alterations in large-scale functional networks of the rodent brain

    NARCIS (Netherlands)

    Henckens, Marloes J A G; van der Marel, Kajo; van der Toorn, A|info:eu-repo/dai/nl/138484821; Pillai, Anup G.; Fernández, Guillén; Dijkhuizen, Rick M.|info:eu-repo/dai/nl/174680058; Joëls, Marianne

    2015-01-01

    Stress-related psychopathology is associated with altered functioning of large-scale brain networks. Animal research into chronic stress, one of the most prominent environmental risk factors for development of psychopathology, has revealed molecular and cellular mechanisms potentially contributing

  8. Size scale dependence of compressive instabilities in layered composites in the presence of stress gradients

    DEFF Research Database (Denmark)

    Poulios, Konstantinos; Niordson, Christian Frithiof

    2016-01-01

    compressive stress but also on spatial stress or strain gradients, rendering failure initiation size scale dependent. The present work demonstrates and investigates the aforementioned effect through numerical simulations of periodically layered structures withnotches and holes under bending and compressive...

  9. Reliability and Validity of the 4-Item Version of the Korean Perceived Stress Scale.

    Science.gov (United States)

    Kim, Hee-Ju

    2016-12-01

    This study was designed to evaluate the reliability (internal consistency, reproducibility over time, and measurement precision) and validity (factorial, convergent, and concurrent validity) of the 4-item Korean Perceived Stress Scale in comparison to the 10-item Korean Perceived Stress Scale. Participants were 650 students from seven schools of nursing in South Korea. Measures included Korean versions of the Perceived Stress Scale, the Pittsburgh Sleep Quality Index, and a single-item quality-of-life measure. The 4-item Perceived Stress Scale had lower Cronbach alpha than the 10-item Perceived Stress Scale (.65 vs. .80), but its item-total correlations (.35-.47) and split-half coefficient (.81) were comparable to the 10-item Perceived Stress Scale (item-total correlations = .20-.56; split-half coefficient = .82). Reproducibility of the 4-item scale after a 1-week interval (r = .67, ICC absolute agreement = .64) was similar to the 10-item scale (r = .70, ICC absolute agreement = .65). The standard error of measurement was slightly higher in the 4-item scale. Scale constructs of the two were identical in exploratory factor analysis. The two scales were highly correlated (r = .93) and showed similar levels of concurrent validity with sleep quality and quality of life. In conclusion, the 4- and 10-item Korean Perceived Stress Scale are similar in psychometric qualities. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  10. Psychometric analysis of the Ten-Item Perceived Stress Scale.

    Science.gov (United States)

    Taylor, John M

    2015-03-01

    Although the 10-item Perceived Stress Scale (PSS-10) is a popular measure, a review of the literature reveals 3 significant gaps: (a) There is some debate as to whether a 1- or a 2-factor model best describes the relationships among the PSS-10 items, (b) little information is available on the performance of the items on the scale, and (c) it is unclear whether PSS-10 scores are subject to gender bias. These gaps were addressed in this study using a sample of 1,236 adults from the National Survey of Midlife Development in the United States II. Based on self-identification, participants were 56.31% female, 77% White, 17.31% Black and/or African American, and the average age was 54.48 years (SD = 11.69). Findings from an ordinal confirmatory factor analysis suggested the relationships among the items are best described by an oblique 2-factor model. Item analysis using the graded response model provided no evidence of item misfit and indicated both subscales have a wide estimation range. Although t tests revealed a significant difference between the means of males and females on the Perceived Helplessness Subscale (t = 4.001, df = 1234, p < .001), measurement invariance tests suggest that PSS-10 scores may not be substantially affected by gender bias. Overall, the findings suggest that inferences made using PSS-10 scores are valid. However, this study calls into question inferences where the multidimensionality of the PSS-10 is ignored. 2015 APA, all rights reserved

  11. Dyspepsia and Depression, Anxiety, Stress Scales (DASS Score

    Directory of Open Access Journals (Sweden)

    Gontar Alamsyah Siregar

    2016-05-01

    Full Text Available Background: Dyspepsia is a constellation of symptoms referable to the gastroduodenal region of the upper gastrointestinal tract. Emotional disturbances are often associated with dyspepsia and have been proposed as one of the possible causes of dyspepsia. This study was aimed to evaluate the difference between the severity of dyspepsia using porto alegre dyspeptic symptoms questionnaire (PADYQ and emotional disturbances using depression, anxiety, stress scales (DASS. Method: This study was a cross-sectional analytical study. All the subjects were evaluated using PADYQ and DASS. PADYQ is classified into four categories (no, mild, moderate and severe dyspepsia symptoms. Data was analyzed using Independent t-test and Mann-Whitney test. A p < 0.05 was considered as statistically significant. Results: There were 90 subjects that enrolled in this study, consisted of 47 (52.2% males and 43 (47.8% females. Thirty three (36.7% subjects had PADYQ score was < 6, while it was ≥ 6 in the other 57 (63.3% subjects. DASS scores were significantly different in subjects without dyspepsia symptoms compared to subjects with dyspepsia symptoms. There is a difference in DASS scores between subjects with different categories of dyspepsia symptoms (p < 0.05. Conclusion: There was a difference in the severity of emotional disturbances among subjects with dyspepsia symptoms and without dyspepsia symptoms. The severity of emotional disturbances parallel with the severity of dyspepsia. Evaluation of emotional disturbances in case of dyspepsia will be helpful in the management of dyspepsia.

  12. The Perceived Stress Reactivity Scale for adolescent athletes

    OpenAIRE

    Britton, Darren; Kavanagh, Emma J.; Polman, R.

    2017-01-01

    Individual differences play a significant role in the outcomes experienced by adolescent athletes, in what is a highly stressful period of their development. Stress reactivity is a stable individual difference underlying the broad variability in responses to stress, which has received very little attention within sport. Conventional physiological measures of reactivity can be time-consuming, costly, and invasive; therefore, this study aimed to adapt a self-report measure of Perceived Stress R...

  13. Examining perceptions of academic stress and its sources among university students: The Perception of Academic Stress Scale

    OpenAIRE

    Dalia Bedewy; Adel Gabriel

    2015-01-01

    The development of a scale to measure perceived sources of academic stress among university students. Based on empirical evidence and recent literature review, we developed an 18-item scale to measure perceptions of academic stress and its sources. Experts ( n  = 12) participated in the content validation process of the instrument before it was administered to ( n  = 100) students. The developed instrument has internal consistency reliability of 0.7 (Cronbach’s alpha), there was evidence for ...

  14. Assessing Stress in Cancer Patients: A Second-Order Factor Analysis Model for the Perceived Stress Scale

    Science.gov (United States)

    Golden-Kreutz, Deanna M.; Browne, Michael W.; Frierson, Georita M.; Andersen, Barbara L.

    2004-01-01

    Using the Perceived Stress Scale (PSS), perceptions of global stress were assessed in 111women following breast cancer surgery and at 12 and 24 months later. This is the first study to factor analyze the PSS. The PSS data were factor analyzed each time using exploratory factor analysis with oblique direct quartimin rotation. Goodness-of-fit…

  15. The Child Stress Disorders Checklist-Short Form: A 4-Item Scale of Traumatic Stress Symptoms in Children

    Science.gov (United States)

    Enlow, Michelle Bosquet; Kassam-Adams, Nancy; Saxe, Glenn

    2010-01-01

    Objective To develop a user-friendly scale that measures traumatic stress responses in injured children. Though injured youth are at high risk for traumatic stress reactions and negative sequelae, there are limited options available for assessing risk, particularly in acute settings. Method Participants were children and adolescents (ages 6–18) hospitalized with burns or acute injuries (N = 147). During hospitalization, parents and nurses completed the Child Stress Disorders Checklist (CSDC), a 36-item observer-report measure of traumatic stress symptoms. Other established measures of child traumatic stress were completed by parents and children during hospitalization and 3 months post-injury. A brief version of the CSDC was created using standard psychometric scale development techniques. The psychometric properties of the resultant scale were compared to that of the original CSDC. Results A 4-item scale (CSDC-Short Form, CSDC-SF) emerged that demonstrated internal, inter-rater, and test-retest reliability and concurrent, discriminant, and predictive validity comparable to that of the full scale. Conclusions The CSDC-SF assesses traumatic stress reactions in injured children. Because the measure is very short and does not require specialized training for administration or interpretation, it may be a useful tool for providers who treat injured youth to indentify those at risk for traumatic stress reactions. PMID:20430237

  16. Resolving terrestrial ecosystem processes along a subgrid topographic gradient for an earth-system model

    Science.gov (United States)

    Subin, Z M; Milly, Paul C.D.; Sulman, B N; Malyshev, Sergey; Shevliakova, E

    2014-01-01

    Soil moisture is a crucial control on surface water and energy fluxes, vegetation, and soil carbon cycling. Earth-system models (ESMs) generally represent an areal-average soil-moisture state in gridcells at scales of 50–200 km and as a result are not able to capture the nonlinear effects of topographically-controlled subgrid heterogeneity in soil moisture, in particular where wetlands are present. We addressed this deficiency by building a subgrid representation of hillslope-scale topographic gradients, TiHy (Tiled-hillslope Hydrology), into the Geophysical Fluid Dynamics Laboratory (GFDL) land model (LM3). LM3-TiHy models one or more representative hillslope geometries for each gridcell by discretizing them into land model tiles hydrologically coupled along an upland-to-lowland gradient. Each tile has its own surface fluxes, vegetation, and vertically-resolved state variables for soil physics and biogeochemistry. LM3-TiHy simulates a gradient in soil moisture and water-table depth between uplands and lowlands in each gridcell. Three hillslope hydrological regimes appear in non-permafrost regions in the model: wet and poorly-drained, wet and well-drained, and dry; with large, small, and zero wetland area predicted, respectively. Compared to the untiled LM3 in stand-alone experiments, LM3-TiHy simulates similar surface energy and water fluxes in the gridcell-mean. However, in marginally wet regions around the globe, LM3-TiHy simulates shallow groundwater in lowlands, leading to higher evapotranspiration, lower surface temperature, and higher leaf area compared to uplands in the same gridcells. Moreover, more than four-fold larger soil carbon concentrations are simulated globally in lowlands as compared with uplands. We compared water-table depths to those simulated by a recent global model-observational synthesis, and we compared wetland and inundated areas diagnosed from the model to observational datasets. The comparisons demonstrate that LM3-TiHy has the

  17. Study on serum cortisol and perceived stress scale in the police constables.

    Science.gov (United States)

    Walvekar, Sanjeev S; Ambekar, Jeevan G; Devaranavadagi, Basavaraj B

    2015-02-01

    The occupational stress may be more among the police constables. Under the stressed conditions, the body secretes more Cortisol. Elevated serum cortisol levels significantly correlate with the symptoms of metabolic Syndrome. Perceived stress scale (PSS) is the most widely used psychological tool for measuring the perception of stress. The objective of this study was to examine the association between perceived stress and Serum Cortisol and also to explore stress as an occupational risk factor which may lead to metabolic syndrome. We measured Serum Cortisol, Lipid profile, Blood Glucose and HbA1c in both Police constables and the general population. Also to evaluate the occupational stress, the questionnaire consisting of Perceived stress scale -14 items was used. A positive correlation was found between Serum Cortisol and perceived stress scale, Blood Glucose, HbA1c. The biochemical parameters were found to be elevated in police constables compared to controls. It was found that among 108 policemen, 38% were confirmed with cardiometabolic syndrome. The relation between Serum Cortisol and perceived stress scale indicates the severity of occupational stress the police constables are experiencing. So the occupation based health program for lifestyle changes, modification in job related rules and regulations will help to avert further complications and keep police personnel healthy.

  18. Examining perceptions of academic stress and its sources among university students: The Perception of Academic Stress Scale

    Science.gov (United States)

    Bedewy, Dalia

    2015-01-01

    The development of a scale to measure perceived sources of academic stress among university students. Based on empirical evidence and recent literature review, we developed an 18-item scale to measure perceptions of academic stress and its sources. Experts (n = 12) participated in the content validation process of the instrument before it was administered to (n = 100) students. The developed instrument has internal consistency reliability of 0.7 (Cronbach’s alpha), there was evidence for content validity, and factor analysis resulted in four correlated and theoretically meaningful factors. We developed and tested a scale to measure academic stress and its sources. This scale takes 5 minutes to complete. PMID:28070363

  19. Examining perceptions of academic stress and its sources among university students: The Perception of Academic Stress Scale.

    Science.gov (United States)

    Bedewy, Dalia; Gabriel, Adel

    2015-07-01

    The development of a scale to measure perceived sources of academic stress among university students. Based on empirical evidence and recent literature review, we developed an 18-item scale to measure perceptions of academic stress and its sources. Experts ( n  = 12) participated in the content validation process of the instrument before it was administered to ( n  = 100) students. The developed instrument has internal consistency reliability of 0.7 (Cronbach's alpha), there was evidence for content validity, and factor analysis resulted in four correlated and theoretically meaningful factors. We developed and tested a scale to measure academic stress and its sources. This scale takes 5 minutes to complete.

  20. Examining perceptions of academic stress and its sources among university students: The Perception of Academic Stress Scale

    Directory of Open Access Journals (Sweden)

    Dalia Bedewy

    2015-07-01

    Full Text Available The development of a scale to measure perceived sources of academic stress among university students. Based on empirical evidence and recent literature review, we developed an 18-item scale to measure perceptions of academic stress and its sources. Experts ( n  = 12 participated in the content validation process of the instrument before it was administered to ( n  = 100 students. The developed instrument has internal consistency reliability of 0.7 (Cronbach’s alpha, there was evidence for content validity, and factor analysis resulted in four correlated and theoretically meaningful factors. We developed and tested a scale to measure academic stress and its sources. This scale takes 5 minutes to complete.

  1. Gender Effect According to Item Directionality on the Perceived Stress Scale for Adults with Multiple Sclerosis

    Science.gov (United States)

    Gitchel, W. Dent; Roessler, Richard T.; Turner, Ronna C.

    2011-01-01

    Assessment is critical to rehabilitation practice and research, and self-reports are a commonly used form of assessment. This study examines a gender effect according to item wording on the "Perceived Stress Scale" for adults with multiple sclerosis. Past studies have demonstrated two-factor solutions on this scale and other scales measuring…

  2. Assessing Stress in Cancer Patients: A Second-Order Factor Analysis Model for the Perceived Stress Scale

    OpenAIRE

    Golden-Kreutz, Deanna M.; Browne, Michael W.; Frierson, Georita M.; Andersen, Barbara L.

    2004-01-01

    Using the Perceived Stress Scale (PSS), perceptions of global stress were assessed in 111 women following breast cancer surgery and at 12 and 24 months later. This is the first study to factor analyze the PSS. The PSS data were factor analyzed each time using exploratory factor analysis with oblique direct quartimin rotation. Goodness-of-fit indices (root mean square error of approximation [RMSEA]), magnitude and pattern of factor loadings, and confidence interval data revealed a two-factor s...

  3. [Brazilian version of the Perceived Stress Scale: translation and validation for the elderly].

    Science.gov (United States)

    Luft, Caroline Di Bernardi; Sanches, Sabrina de Oliveira; Mazo, Giovana Zarpellon; Andrade, Alexandro

    2007-08-01

    To translate the Perceived Stress Scale into Brazilian Portuguese, and to assess its validity for measuring perceived stress of Brazilian elderly. The scale was translated and tested in its full version including 14 questions and in a shortened version including ten questions. The whole translation process consisted of translation, back-translation and committee review. The translated version was applied, by means of interview, to 76 elders aged on average 70.04 years (SD=6.34; range: 60-84). The internal consistency was verified by means of the Cronbach's alpha coefficient and the construct validity was analyzed by means of factorial exploratory analysis with varimax rotation. Full and shortened score means were analyzed comparing the perceived stress in terms of self-assessment of health, perceived socioeconomic condition, marital status, and living conditions, among others. As for reliability, the full version has showed similar internal consistency (r=0.82) compared to the shortened one (r=0.83). The factorial analysis found two factors for the full and one factor for the shortened scale. Question 12 showed the lowest factorial loads. When analyzing PSS likelihood of differentiating the perceived stress in terms of the study variables, it was found the full scale had greater differences in perceived stress than the shortened scale. The Perceived Stress Scale proved to be a clear and reliable tool to measure the perceived stress of Brazilian elderly, showing suitable psychometric performance.

  4. The German version of the Perceived Stress Scale - psychometric characteristics in a representative German community sample.

    Science.gov (United States)

    Klein, Eva M; Brähler, Elmar; Dreier, Michael; Reinecke, Leonard; Müller, Kai W; Schmutzer, Gabriele; Wölfling, Klaus; Beutel, Manfred E

    2016-05-23

    The Perceived Stress Scale Cohen (J Health Soc Behav 24:385-96, 1983) is a widely and well-established self-report scale measuring perceived stress. However, the German version of the PSS-10 has not yet been validated. Thus, the purposes of this representative study were to psychometrically evaluate the PSS-10, and to provide norm values for the German population. The PSS-10 and standardized scales of depression, anxiety, fatigue, procrastination and life satisfaction were administered to a representative, randomly selected German community sample consisting of 1315 females and 1148 male participants in the age range from 14 to 90 years. The results demonstrated a good internal consistency and construct validity. Perceived stress was consistently associated with depression, anxiety, fatigue, procrastination and reduced life satisfaction. Confirmatory factor analysis revealed a bi-dimensional structure with two related latent factors. Regarding demographic variables, women reported a higher level of stress than men. Perceived stress decreased with higher education, income and employment status. Older and married participants felt less stressed than younger and unmarried participants. The PSS-10 is a reliable, valid and economic instrument for assessing perceived stress. As psychological stress is associated with an increased risk of diseases, identifying subpopulations with higher levels of stress is essential. Due to the dependency of the perceived stress level on demographic variables, particularly age and sex, differentiated norm values are needed, which are provided in this paper.

  5. Quantification of marine aerosol subgrid variability and its correlation with clouds based on high-resolution regional modeling: Quantifying Aerosol Subgrid Variability

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Guangxing; Qian, Yun; Yan, Huiping; Zhao, Chun; Ghan, Steven J.; Easter, Richard C.; Zhang, Kai

    2017-06-16

    One limitation of most global climate models (GCMs) is that with the horizontal resolutions they typically employ, they cannot resolve the subgrid variability (SGV) of clouds and aerosols, adding extra uncertainties to the aerosol radiative forcing estimation. To inform the development of an aerosol subgrid variability parameterization, here we analyze the aerosol SGV over the southern Pacific Ocean simulated by the high-resolution Weather Research and Forecasting model coupled to Chemistry. We find that within a typical GCM grid, the aerosol mass subgrid standard deviation is 15% of the grid-box mean mass near the surface on a 1 month mean basis. The fraction can increase to 50% in the free troposphere. The relationships between the sea-salt mass concentration, meteorological variables, and sea-salt emission rate are investigated in both the clear and cloudy portion. Under clear-sky conditions, marine aerosol subgrid standard deviation is highly correlated with the standard deviations of vertical velocity, cloud water mixing ratio, and sea-salt emission rates near the surface. It is also strongly connected to the grid box mean aerosol in the free troposphere (between 2 km and 4 km). In the cloudy area, interstitial sea-salt aerosol mass concentrations are smaller, but higher correlation is found between the subgrid standard deviations of aerosol mass and vertical velocity. Additionally, we find that decreasing the model grid resolution can reduce the marine aerosol SGV but strengthen the correlations between the aerosol SGV and the total water mixing ratio (sum of water vapor, cloud liquid, and cloud ice mixing ratios).

  6. The construct validity of the Perceived Stress Scale

    DEFF Research Database (Denmark)

    Nielsen, Marie Germund; Ørnbøl, Eva; Vestergaard, Mogens

    2016-01-01

    særligt de positivt formulerede spørgsmål, der giver udfordringer, og kønsforskelle kan ikke alene forklare de to dimensioner i skalaen. Der er i dag ingen psykometrisk test til måling af stress hos patienter i almen praksis, og et muligt instrument kunne være PSS-10 skalaen, hvis de identificerede...

  7. Psychometric Validation of Stress and Compliance Scale for ...

    African Journals Online (AJOL)

    ... evaluate the fit of the model (two-factor). Results: Barlett's test of sphericity was 1603.417 (p < 0.001) while Kaiser-Meyer-Olkin measure of sampling adequacy was 0.83. Varimax rotation was conducted with these two identified factors. Factor A integrated items 1, 2, 3, 6, 9 and 10, labeled as 'Perceived Stress' while Factor ...

  8. Review of the Psychometric Evidence of the Perceived Stress Scale

    Directory of Open Access Journals (Sweden)

    Eun-Hyun Lee, RN, PhD

    2012-12-01

    Conclusion: Overall, the PSS is an easy-to-use questionnaire with established acceptable psychometric properties. However, future studies should evaluate these psychometric properties in greater depth, and validate the scale using diverse populations.

  9. Stress determination in thermally grown alumina scales using ruby luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Renusch, D.; Veal, B.W.; Koshelev, I.; Natesan, K.; Grimsditch [Argonne National Lab., IL (United States); Hou, P.Y. [Lawrence Berkeley Lab., CA (United States)

    1996-06-01

    By exploiting the strain dependence of the ruby luminescence line, we have measured the strain in alumina scales thermally grown on Fe-Cr- Al alloys. Results are compared and found to be reasonably consistent with strains determined using x rays. Oxidation studies were carried out on alloys Fe - 5Cr - 28Al and Fe - 18Cr - 10Al (at.%). Significantly different levels of strain buildup were observed in scales on these alloys. Results on similar alloys containing a ``reactive element`` (Zr or Hf) in dilute quantity are also presented. Scales on alloys containing a reactive element (RE) can support significantly higher strains than scales on RE-free alloys. With the luminescence technique, strain relief associated with spallation thresholds is readily observed.

  10. Development of an Acculturative Stress Scale for International Students: preliminary findings.

    Science.gov (United States)

    Sandhu, D S; Asrabadi, B R

    1994-08-01

    Description of the development and testing of a new 36-item scale in Likert format, designed to assess the acculturative stress of international students, includes perceived discrimination, homesickness, fear, guilt, perceived hatred, and stress due to change (cultural shock), identified as major contributing factors. The psychometric properties of this instrument and implications for use by mental health practitioners are discussed.

  11. Educational Stress Scale for Adolescents: Development, Validity, and Reliability with Chinese Students

    Science.gov (United States)

    Sun, Jiandong; Dunne, Michael P.; Hou, Xiang-yu; Xu, Ai-qiang

    2011-01-01

    This article describes the development and initial validation of a new instrument to measure academic stress--the Educational Stress Scale for Adolescents (ESSA). A series of cross-sectional questionnaire surveys were conducted with more than 2,000 Chinese adolescents to examine the psychometric properties. The final 16-item ESSA contains five…

  12. Further Psychometric Support for the 10-Item Version of the Perceived Stress Scale

    Science.gov (United States)

    Roberti, Jonathan W.; Harrington, Lisa N.; Storch, Eric A.

    2006-01-01

    Because of increased stress conditions in college students, updated psychometrics of the Perceived Stress Scale, 10-item version (PSS-10; S. Cohen & G. Williamson, 1988) are necessary. Participants were 281 undergraduates at 3 public universities. An exploratory factor analysis revealed a 2-factor structure measuring Perceived Helplessness and…

  13. Factor Structure of the Acute Stress Disorder Scale in a Sample of Hurricane Katrina Evacuees

    Science.gov (United States)

    Edmondson, Donald; Mills, Mary Alice; Park, Crystal L.

    2010-01-01

    Acute stress disorder (ASD) is a poorly understood and controversial diagnosis (A. G. Harvey & R. A. Bryant, 2002). The present study used confirmatory factor analysis (CFA) to test the factor structure of the most widely used self-report measure of ASD, the Acute Stress Disorder Scale (R. A. Bryant, M. L. Moulds, & R. M. Guthrie, 2000),…

  14. Aerosol indirect effects in the ECHAM5-HAM2 climate model with subgrid cloud microphysics in a stochastic framework

    Science.gov (United States)

    Tonttila, Juha; Räisänen, Petri; Järvinen, Heikki

    2015-04-01

    Representing cloud properties in global climate models remains a challenging topic, which to a large extent is due to cloud processes acting on spatial scales much smaller than the typical model grid resolution. Several attempts have been made to alleviate this problem. One such method was introduced in the ECHAM5-HAM2 climate model by Tonttila et al. (2013), where cloud microphysical properties, along with the processes of cloud droplet activation and autoconversion, were computed using an ensemble of stochastic subcolumns within the climate model grid columns. Moreover, the subcolumns were sampled for radiative transfer using the Monte Carlo Independent Column Approximation approach. The same model version is used in this work (Tonttila et al. 2014), where 5-year nudged integrations are performed with a series of different model configurations. Each run is performed twice, once with pre-industrial (PI, year 1750) aerosol emission conditions and once with present-day (PD, year 2000) conditions, based on the AEROCOM emission inventories. The differences between PI and PD simulations are used to estimate the impact of anthropogenic aerosols on clouds and the aerosol indirect effect (AIE). One of the key results is that when both cloud activation and autoconversion are computed in the subcolumn space, the aerosol-induced PI-to-PD change in the global-mean liquid water path is up to 19 % smaller than in the reference with grid-scale computations. Together with similar changes in the cloud droplet number concentration, this influences the cloud radiative effects and thus the AIE, which is estimated as the difference in the net cloud radiative effect between PI and PD conditions. Accordingly, the AIE is reduced by 14 %, from 1.59 W m-2 in the reference model version to 1.37 W m-2 in the experimental model configuration. The results of this work explicitly show that careful consideration of the subgrid variability in cloud microphysical properties and consistent

  15. The effects of the sub-grid variability of soil and land cover data on agricultural droughts in Germany

    Science.gov (United States)

    Kumar, Rohini; Samaniego, Luis; Zink, Matthias

    2013-04-01

    Simulated soil moisture from land surface or water balance models is increasingly used to characterize and/or monitor the development of agricultural droughts at regional and global scales (e.g. NLADS, EDO, GLDAS). The skill of these models to accurately replicate hydrologic fluxes and state variables is strongly dependent on the quality meteorological forcings, the conceptualization of dominant processes, and the parameterization scheme used to incorporate the variability of land surface properties (e.g. soil, topography, and vegetation) at a coarser spatial resolutions (e.g. at least 4 km). The goal of this study is to analyze the effects of the sub-grid variability of soil texture and land cover properties on agricultural drought statistics such as duration, severity, and areal extent. For this purpose, a process based mesoscale hydrologic model (mHM) is used to create two sets of daily soil moisture fields over Germany at the spatial resolution of (4 × 4) km2 from 1950 to 2011. These simulations differ from each other only on the manner in which the land surface properties are accounted within the model. In the first set, soil moisture fields are obtained with the multiscale parameter regionalization (MPR) scheme (Samaniego, et. al. 2010, Kumar et. al. 2012), which explicitly takes the sub-grid variability of soil texture and land cover properties into account. In the second set, on the contrary, a single dominant soil and land cover class is used for ever grid cell at 4 km. Within each set, the propagation of the parameter uncertainty into the soil moisture simulations is also evaluated using an ensemble of 100 best global parameter sets of mHM (Samaniego, et. al. 2012). To ensure comparability, both sets of this ensemble simulations are forced with the same fields of meteorological variables (e.g., precipitation, temperature, and potential evapotranspiration). Results indicate that both sets of model simulations, with and without the sub-grid variability of

  16. Cross-cultural validity of the masculine and feminine gender role stress scales.

    Science.gov (United States)

    van Well, Sonja; Kolk, Annemarie M; Arrindell, Willem A

    2005-06-01

    The objective was to examine the usefulness of Dutch versions of the Masculine Gender Role Stress (MGRS; Eisler & Skidmore, 1987) Scale and the Feminine Gender Role Stress (Gillespie & Eisler, 1992) Scale in The Netherlands. Undergraduate students (N = 2,239) completed both gender role stress scales. A subgroup (n = 508) also completed questionnaires about masculinity-femininity and daily hassles. With regard to both gender role stress scales, results of confirmatory factor analyses supported the original 5-factor structures and revealed no cross-sex differences on the factor models. Reliability and homogeneity indexes were all well within acceptable to satisfactory limits. Further evidence of construct validity was found in (a) medium to large correlations with daily hassles, (b) sex differences on the FGRS scale, and (c) small to medium correlations with masculinity-femininity. The major discrepancy with previous studies was that for Dutch female and male students, the MGRS scale was not sex specific. Taken together, this study sustained the utility of both gender role stress scales for use in The Netherlands.

  17. Sub-Grid Modeling of Electrokinetic Effects in Micro Flows

    Science.gov (United States)

    Chen, C. P.

    2005-01-01

    Advances in micro-fabrication processes have generated tremendous interests in miniaturizing chemical and biomedical analyses into integrated microsystems (Lab-on-Chip devices). To successfully design and operate the micro fluidics system, it is essential to understand the fundamental fluid flow phenomena when channel sizes are shrink to micron or even nano dimensions. One important phenomenon is the electro kinetic effect in micro/nano channels due to the existence of the electrical double layer (EDL) near a solid-liquid interface. Not only EDL is responsible for electro-osmosis pumping when an electric field parallel to the surface is imposed, EDL also causes extra flow resistance (the electro-viscous effect) and flow anomaly (such as early transition from laminar to turbulent flow) observed in pressure-driven microchannel flows. Modeling and simulation of electro-kinetic effects on micro flows poses significant numerical challenge due to the fact that the sizes of the double layer (10 nm up to microns) are very thin compared to channel width (can be up to 100 s of m). Since the typical thickness of the double layer is extremely small compared to the channel width, it would be computationally very costly to capture the velocity profile inside the double layer by placing sufficient number of grid cells in the layer to resolve the velocity changes, especially in complex, 3-d geometries. Existing approaches using "slip" wall velocity and augmented double layer are difficult to use when the flow geometry is complicated, e.g. flow in a T-junction, X-junction, etc. In order to overcome the difficulties arising from those two approaches, we have developed a sub-grid integration method to properly account for the physics of the double layer. The integration approach can be used on simple or complicated flow geometries. Resolution of the double layer is not needed in this approach, and the effects of the double layer can be accounted for at the same time. With this

  18. The Storm Surge and Sub-Grid Inundation Modeling in New York City during Hurricane Sandy

    Directory of Open Access Journals (Sweden)

    Harry V. Wang

    2014-03-01

    Full Text Available Hurricane Sandy inflicted heavy damage in New York City and the New Jersey coast as the second costliest storm in history. A large-scale, unstructured grid storm tide model, Semi-implicit Eulerian Lagrangian Finite Element (SELFE, was used to hindcast water level variation during Hurricane Sandy in the mid-Atlantic portion of the U.S. East Coast. The model was forced by eight tidal constituents at the model’s open boundary, 1500 km away from the coast, and the wind and pressure fields from atmospheric model Regional Atmospheric Modeling System (RAMS provided by Weatherflow Inc. The comparisons of the modeled storm tide with the NOAA gauge stations from Montauk, NY, Long Island Sound, encompassing New York Harbor, Atlantic City, NJ, to Duck, NC, were in good agreement, with an overall root mean square error and relative error in the order of 15–20 cm and 5%–7%, respectively. Furthermore, using large-scale model outputs as the boundary conditions, a separate sub-grid model that incorporates LIDAR data for the major portion of the New York City was also set up to investigate the detailed inundation process. The model results compared favorably with USGS’ Hurricane Sandy Mapper database in terms of its timing, local inundation area, and the depth of the flooding water. The street-level inundation with water bypassing the city building was created and the maximum extent of horizontal inundation was calculated, which was within 30 m of the data-derived estimate by USGS.

  19. Comparability of Two Administration Formats of the Keane Posttraumatic Stress Disorder Scale.

    Science.gov (United States)

    Lyons, Judith A.; Scotti, Joseph R.

    1994-01-01

    The utility of using the Keane Minnesota Multiphasic Personality Inventory (MMPI) Posttraumatic Stress Disorder scale as an instrument separate from the full MMPI was evaluated. Results with 175 African American and white male veterans support use of the scale as an alternative to the full test. (SLD)

  20. Enhancing Representation of Subgrid Land Surface Characteristics in the Community Land Model

    Science.gov (United States)

    Ke, Y.; Coleman, A.; Leung, L.; Huang, M.; Li, H.; Wigmosta, M. S.

    2011-12-01

    The Community Land Model (CLM) is the land surface model used in the Community Earth System Model (CESM). In CLM each grid cell is composed of subgrid land units, snow/soil columns and plant functional types (PFTs). In the current version of CLM (CLM4.0), land surface parameters such as vegetated/non-vegetated land cover and surface characteristics including fractional glacier, lake, wetland, urban area, and PFT, and its associated leaf area index (LAI), stem area index (SAI), and canopy top and bottom heights are provided at 0.5° or coarser resolution. This study aims to enhance the representation of the land surface data by (1) creating higher resolution (0.05° or higher) global land surface parameters, and (2) developing an effective and accurate subgrid classification scheme for elevation and PFTs so that variations of land surface processes due to the subgrid distribution of PFTs and elevation can be represented in CLM. To achieve higher-resolution global land surface parameters, MODIS 500m land cover product (MCD12Q1) collected in 2005 was used to generate percentage of glacier, lake, wetland, and urban area and fractional PFTs at 0.05° resolution. Spatially and temporally continuous and consistent global LAI data re-processed and improved from MOD15A2 (http://globalchange.bnu.edu.cn/research/lai), combined with the PFT data, was used to create LAI, SAI, and, canopy top and bottom height data. 30-second soil texture data was obtained from a hybrid 30-second State Soil Geographic Database (STATSGO) and the 5-minute Food and Agriculture Organization two-layer 16-category soil texture dataset. The relationship between global distribution of PFTs and 1-km resolution elevation data is being analyzed to develop a subgrid classification of PFT and elevation. Statistical analysis is being conducted to compare different subgrid classification methods to select a method that explains the highest percentage of subgrid variance in both PFT and elevation distribution

  1. Fracture Toughness Prediction under Compressive Residual Stress by Using a Stress-Distribution T-Scaling Method

    Directory of Open Access Journals (Sweden)

    Toshiyuki Meshii

    2017-12-01

    Full Text Available The improvement in the fracture toughness Jc of a material in the ductile-to-brittle transition temperature region due to compressive residual stress (CRS was considered in this study. A straightforward fracture prediction was performed for a specimen with mechanical CRS by using the T-scaling method, which was originally proposed to scale the fracture stress distributions between different temperatures. The method was validated for a 780-MPa-class high-strength steel and 0.45% carbon steel. The results showed that the scaled stress distributions at fracture loads without and with CRS are the same, and that Jc improvement was caused by the loss in the one-to-one correspondence between J and the crack-tip stress distribution. The proposed method is advantageous in possibly predicting fracture loads for specimens with CRS by using only the stress–strain relationship, and by performing elastic-plastic finite element analysis, i.e., without performing fracture toughness testing on specimens without CRS.

  2. Determining Factors for Stress Perception Assessed with the Perceived Stress Scale (PSS-4) in Spanish and Other European Samples.

    Science.gov (United States)

    Vallejo, Miguel A; Vallejo-Slocker, Laura; Fernández-Abascal, Enrique G; Mañanes, Guillermo

    2018-01-01

    Objective: Stress perception depends on cultural and social aspects that vary from one country to another. One of the most widely disseminated methods of assessing psychological stress is the Perceived Stress Scale (PSS-4). Therefore, in order to identify these factors and their impact on mental health, the present study compares the PSS-4 results among three European countries (Great Britain, France and Spain). This study focuses on PSS-4 results within a Spanish sample to determine: (1) normative data, reliability and validity of PSS-4 in a Spanish sample and (2) how stress perception changes depending on cultural and social factors. Methods: The data were obtained from a website representing a service of a smoking cessation program, the study represented a service that was open to all individuals. The number of participants were 37,451. They reported their age, gender, nationality, marital status, education and employment status, and completed two psychological questionnaires (PPS-4 and the anxiety and depression scales of the Symptom Checklist-90-Revised, SCL 90-R). Results: The PSS-4 scores could differentiate between relevant sociodemographic variables (such as sex, age, nationality, marital status, education, parental status, employment status, and income class). The PSS-4 scores showed a positive correlation with the SCL 90-R anxiety and depression scales. The normed values for interpreting the PSS-4 scores are presented. The PSS-4 showed adequate internal consistency and reliability. Conclusions: The PSS-4 is a useful instrument for assessing stress perception levels in the general population in different countries. Its internal consistency is sufficient for a 4-item scale.

  3. A large-scale perspective on stress-induced alterations in resting-state networks

    Science.gov (United States)

    Maron-Katz, Adi; Vaisvaser, Sharon; Lin, Tamar; Hendler, Talma; Shamir, Ron

    2016-02-01

    Stress is known to induce large-scale neural modulations. However, its neural effect once the stressor is removed and how it relates to subjective experience are not fully understood. Here we used a statistically sound data-driven approach to investigate alterations in large-scale resting-state functional connectivity (rsFC) induced by acute social stress. We compared rsfMRI profiles of 57 healthy male subjects before and after stress induction. Using a parcellation-based univariate statistical analysis, we identified a large-scale rsFC change, involving 490 parcel-pairs. Aiming to characterize this change, we employed statistical enrichment analysis, identifying anatomic structures that were significantly interconnected by these pairs. This analysis revealed strengthening of thalamo-cortical connectivity and weakening of cross-hemispheral parieto-temporal connectivity. These alterations were further found to be associated with change in subjective stress reports. Integrating report-based information on stress sustainment 20 minutes post induction, revealed a single significant rsFC change between the right amygdala and the precuneus, which inversely correlated with the level of subjective recovery. Our study demonstrates the value of enrichment analysis for exploring large-scale network reorganization patterns, and provides new insight on stress-induced neural modulations and their relation to subjective experience.

  4. Psychometric evaluation of Turkish version of the Perceived Stress Scale with Turkish college students.

    Science.gov (United States)

    Kaya, Cahit; Tansey, Timothy N; Melekoglu, Macid; Cakiroglu, Orhan; Chan, Fong

    2017-12-20

    The Turkish version of the Perceived Stress Scale (T-PSS-10) measures the extent to which situations in one's life are appraised as stressful. The purpose of this study was to evaluate the measurement structure of T-PSS-10. Two-hundred and thirty-five Turkish university students (93 men and 142 women) completed the T-PSS-10, the Patient Health Questionnaire-9 (PHQ-9), the General Anxiety Disorder 7-Item Scale (GAD-7), and the Inventory of Common Problems (ICP). Confirmatory factor analysis results indicated that a one-factor model did not fit the data, whereas a two-factor correlated model (stress related self-efficacy beliefs, stress related feelings of helplessness) provided a better fit between the model and the data. Significant moderate correlations were found for the stress-related self-efficacy beliefs and stress-related feelings of helplessness factors with depression, anxiety, academic difficulty, relationship problems and health problems. The internal consistency reliability coefficients for the stress-related self-efficacy beliefs and stress-related feelings of helplessness factors were 0.68 and 0.85, respectively. This study provided support for the reliability and validity of T-PSS-10 suggesting that it can be used as a screening instrument by health professionals working with Turkish college students.

  5. Investigation of independent verification and validation of the servicemen occupational stress scale

    Directory of Open Access Journals (Sweden)

    Jia XU

    2012-12-01

    Full Text Available Objective  To examine the reliability and validity of the servicemen occupational stress scale. Methods  A survey with the servicemen occupational stress scale was carried out on 1100 randomly chosen military personnel in the army, and 106 among them also underwent examination with Chinese Military Mental Health Scale (CMMHS at the same time. Results  The Cronbach's α coefficient of total scale was 0.929, and subscales were 0.731-0.857 (P<0.01; the half reliability of total scale was 0.932, and subscales were 0.465-0.881 (P<0.01. The correlation coefficients among factors and between factors and total scale score were 0.699-0.900 (P<0.01. The factors of the servicemen occupational stress scale showed a significant correlation with most factors of the CMMHS, the correlation coefficients were 0.186-0253. According to the results of exploratory factor analysis, it was showed that the scale of the entries in the collation and factors named were more reasonable. According to the results of confirmatory factor analysis, there was a higher degree of accordance between the sample data and the hypothesized structure of factors, with Chi-Square statistic equal to 8293.0, RMSEA (root mean square error of approximation equal to 0.055, RMR (root mean square residual equal to 0.031, TLI (Tucker-Lewis index, CFI (comparative fit index, IFI (incremental fit index and GFI (goodness of fit index 0.919, 0.926, 0.920, 0.915, respectively. Conclusion  The reliability and validity of the servicemen occupational stress scale meet the standards for scale designing.

  6. Field-based observations confirm linear scaling of sand flux with wind stress

    CERN Document Server

    Martin, Raleigh L

    2016-01-01

    Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the sand flux scales with wind speed, largely because models do not agree on how particle speed changes with wind shear velocity. Here, we present comprehensive measurements from three new field sites and three published studies, showing that characteristic saltation layer heights, and thus particle speeds, remain approximately constant with shear velocity. This result implies a linear dependence of saltation flux on wind shear stress, which contrasts with the nonlinear 3/2 scaling used in most aeolian process predictions. We confirm the linear flux law with direct measurements of the stress-flux relationship occurring at each site. Models for dust generation, dune migration, and other processes driven by wind-blown sand on Earth, Mars, and several other planetary surfaces should be modified to account for linear stress-flux scaling.

  7. The psychometric properties of the Perceived Stress Scale-10 among patients with systemic lupus erythematosus.

    Science.gov (United States)

    Mills, S D; Azizoddin, D; Racaza, G Z; Wallace, D J; Weisman, M H; Nicassio, P M

    2017-10-01

    Objective Systemic lupus erythematosus (SLE) is a chronic, multisystem autoimmune disease characterized by periods of remission and recurrent flares, which have been associated with stress. Despite the significance of stress in this disease, the Perceived Stress Scale-10 has yet to be psychometrically evaluated in patients with SLE. Methods Exploratory factor analysis was used to examine the structural validity of the Perceived Stress Scale-10 among patients with SLE ( N = 138) receiving medical care at Cedars Sinai Medical Center. Cronbach's coefficient alpha was used to examine internal consistency reliability, and Pearson product-moment correlations were used to examine convergent validity with measures of anxiety, depression, helplessness, and disease activity. Results Exploratory factor analysis provided support for a two-factor structure (comparative fit index = .95; standardized root mean residual = .04; root mean square error of approximation = .08). Internal consistency reliability was good for both factors (α = .84 and .86). Convergent validity was evidenced via significant correlations with measures of anxiety, depression, and helplessness. There were no significant correlations with the measure of disease activity. Conclusion The Perceived Stress Scale-10 can be used to examine perceived stress among patients with SLE.

  8. Transformation of Holes Emission Paths under Negative Bias Temperature Stress in Deeply Scaled pMOSFETs

    Directory of Open Access Journals (Sweden)

    Yiming Liao

    2015-01-01

    Full Text Available We examine the impact of negative bias temperature (NBT stress on the fluctuations in ID and IG for deeply scaled pMOSFETs and find that the relative high NBT stress triggers IG-RTN and ID-step. Through the analysis of the field dependence of emission constant and the carrier separation measurement, it is found that under the relative high NBT stress some traps keep charged state for very long time, as observing step-like behaviors in ID, while other traps emit charged holes to the gate side through TAT process, which originate both ID-step and ID-RTN.

  9. Measurement invariance of the Depression Anxiety Stress Scales-21 across medical student genders.

    Science.gov (United States)

    Jafari, Peyman; Nozari, Farnoosh; Ahrari, Forooghosadat; Bagheri, Zahra

    2017-03-30

    This study aimed to assess whether male and female Iranian medical students perceived the meaning of the items in the Depression Anxiety Stress Scales-21 consistently. A convenience sample of 783 preclinical medical students from the first to sixth semester was invited to this cross-sectional study. Of the 477 respondents, 238 were male and 239 were female. All participants completed the Persian version of the Depression Anxiety Stress Scales-21. The graded response model was used to assess measurement invariance of the instrument across the gender groups. Categorical confirmatory factor analysis was used to evaluate the construct validity of the measure. Moreover, internal consistency was assessed via Cronbach's Alpha. Statistically significant differential item functioning was flagged for just item 6 in the depression subscales (c2=6.5, df=1, p=0.011). However, removing or retaining the item 6 in the stress subscale did not change our findings significantly, when we compared stress scores across two genders. The results of categorical confirmatory factor analysis supported the fit of the three-factor model of Depression Anxiety Stress Scales-21. Moreover, Cronbach's alpha was greater than 0.7 in depression, anxiety and stress subscales. This study revealed that Depression Anxiety Stress Scales-21 is an invariant measure across male and female medical students. Hence, this reliable and valid instrument can be used for meaningful comparison of distress scores between medical student genders. Gender comparisons of medical students' psychological profiles provide a better insight into gender influences on the outcome of medical education and medical practice.

  10. Groundwater development stress: Global-scale indices compared to regional modeling

    Science.gov (United States)

    Alley, William; Clark, Brian R.; Ely, Matt; Faunt, Claudia

    2018-01-01

    The increased availability of global datasets and technologies such as global hydrologic models and the Gravity Recovery and Climate Experiment (GRACE) satellites have resulted in a growing number of global-scale assessments of water availability using simple indices of water stress. Developed initially for surface water, such indices are increasingly used to evaluate global groundwater resources. We compare indices of groundwater development stress for three major agricultural areas of the United States to information available from regional water budgets developed from detailed groundwater modeling. These comparisons illustrate the potential value of regional-scale analyses to supplement global hydrological models and GRACE analyses of groundwater depletion. Regional-scale analyses allow assessments of water stress that better account for scale effects, the dynamics of groundwater flow systems, the complexities of irrigated agricultural systems, and the laws, regulations, engineering, and socioeconomic factors that govern groundwater use. Strategic use of regional-scale models with global-scale analyses would greatly enhance knowledge of the global groundwater depletion problem.

  11. Construction and evaluation of a self rating scale for stress-induced exhaustion disorder, the Karolinska Exhaustion Disorder Scale.

    Science.gov (United States)

    Besèr, Aniella; Sorjonen, Kimmo; Wahlberg, Kristina; Peterson, Ulla; Nygren, Ake; Asberg, Marie

    2014-02-01

    Prolonged stress (≥ six months) may cause a condition which has been named exhaustion disorder (ED) with ICD-10 code F43.8. ED is characterised by exhaustion, cognitive problems, poor sleep and reduced tolerance to further stress. ED can cause long term disability and depressive symptoms may develop. The aim was to construct and evaluate a self-rating scale, the Karolinska Exhaustion Disorder Scale (KEDS), for the assessment of ED symptoms. A second aim was to examine the relationship between self-rated symptoms of ED, depression, and anxiety using KEDS and the Hospital Anxiety and Depression Scale (HAD). Items were selected based on their correspondence to criteria for ED as formulated by the Swedish National Board of Health and Welfare (NBHW), with seven response alternatives in a Likert-format. Self-ratings performed by 317 clinically assessed participants were used to analyse the scale's psychometric properties. KEDS consists of nine items with a scale range of 0-54. Receiver operating characteristics analysis demonstrated that a cut-off score of 19 was accompanied by high sensitivity and specificity (each above 95%) in the discrimination between healthy subjects and patients with ED. Reliability was satisfactory and confirmatory factor analysis revealed that ED, depression and anxiety are best regarded as different phenomena. KEDS may be a useful tool in the assessment of symptoms of Exhaustion Disorder in clinical as well as research settings. There is evidence that the symptom clusters of ED, anxiety and depression, respectively, reflect three different underlying dimensions. © 2013 The Authors. Scandinavian Journal of Psychology published by Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  12. Psychometric Properties of an Arabic Version of the Depression Anxiety Stress Scales (DASS)

    Science.gov (United States)

    Moussa, Miriam Taouk; Lovibond, Peter; Laube, Roy; Megahead, Hamido A.

    2017-01-01

    Objective: To translate and evaluate the psychometric properties of an Arabic-language version of the Depression Anxiety Stress Scales (DASS). Method: The items were translated, back translated, refined, and tested in an Australian immigrant sample (N = 220). Results: Confirmatory factor analysis showed that the Arabic DASS discriminates between…

  13. Depression, Anxiety and Stress Scale (DASS): The Study of Validity and Reliability

    Science.gov (United States)

    Basha, Ertan; Kaya, Mehmet

    2016-01-01

    The purpose of this study is to examine validity and reliability of the Albanian version of the Depression, Anxiety and Stress Scale (DASS), which is developed by Lovibond and Lovibond (1995). The sample of this study is consisted of 555 subjects who were living in Kosovo. The results of confirmatory factor analysis indicated 42 items loaded on…

  14. Using the Depression, Anxiety, Stress Scales-21 with U.S. Adolescents: An Alternate Models Analysis

    Science.gov (United States)

    Moore, Stephanie A.; Dowdy, Erin; Furlong, Michael J.

    2017-01-01

    As part of universal screening efforts in schools, validated measures that identify internalizing distress are needed. One promising available measure, the Depression, Anxiety, and Stress Scales-21 (DASS-21), has yet to be thoroughly investigated with adolescents in the United States. This study investigated the underlying factor structure of the…

  15. Assessment of the depression, anxiety, and stress scale (DASS-21) in untreated obstructive sleep apnea (OSA)

    DEFF Research Database (Denmark)

    Nanthakumar, Shenooka; Bucks, Romola S.; Skinner, Timothy C.

    2017-01-01

    The assessment of depression in obstructive sleep apnea (OSA) is confounded by symptom overlap. The Depression, Anxiety, and Stress Scale-short form (DASS-21) is a commonly used measure of negative affect, but it not known whether the DASS-21 is suitable for use in an OSA sample. This study...

  16. EARLY PROGNOSTIC SCREENING FOR POSTTRAUMATIC STRESS DISORDER WITH THE DAVIDSON TRAUMA SCALE AND THE SPAN

    NARCIS (Netherlands)

    Sijbrandij, Marit; Olff, Miranda; Opmeer, Brent C.; Carlier, Ingrid V. E.; Gersons, Berthold P. R.

    2008-01-01

    Background: This study examined the accuracy of the 17-item. Dutch version of the Davidson Trauma Scale (DTS) and the four-item SPAN (Startle, Physiological Arousal, Anger and Numbness) to detect survivors at risk for posttraumatic stress disorder (PTSD) within the first 2 weeks after the trauma.

  17. Assessment of Major and Daily Stressful Events During Adolescence: The Adolescent Perceived Events Scale.

    Science.gov (United States)

    Compas, Bruce E.; And Others

    1987-01-01

    Conducted four studies to develop Adolescent Perceived Events Scale (APES), measure of major and daily stressful events during adolescence. Describes test construction, test-retest reliability, and concurrent validity of APES. Summarizes subsequent research showing APES to be significantly related to behavior problems and psychological…

  18. Geomechanical effects of stress shadow created by large-scale destress blasting

    Directory of Open Access Journals (Sweden)

    Isaac Vennes

    2017-12-01

    Full Text Available This study aims to determine if large-scale choked panel destress blasting can provide sufficient beneficial stress reduction in highly-stressed remnant ore pillar that is planned for production. The orebody is divided into 20 stopes over 2 levels, and 2 panels are choke-blasted in the hanging wall to shield the ore pillar by creating a stress shadow around it. A linear-elastic model of the mining system is constructed with finite difference code FLAC3D. The effect of destress blasting in the panels is simulated by applying a fragmentation factor (α to the rock mass stiffness and a stress reduction factor (β to the current state of stress in the region occupied by the destress panels. As an extreme case, the destress panel is also modeled as a void to obtain the maximum possible beneficial effects of destressing and stress shadow. Four stopes are mined in the stress shadow of the panels in 6 lifts and then backfilled. The effect of destress blasting on the remnant ore pillar is quantified based on stress change and brittle shear ratio (BSR in the stress shadow zone compared to the base case without destress blasting. To establish realistic rock fragmentation and stress reduction factors, model results are compared to measured stress changes reported for case studies at Fraser and Brunswick mines. A 1.5 MPa immediate stress decrease was observed 20 m away from the panel at Fraser Mine, and a 4 MPa immediate stress decrease was observed 25 m away at Brunswick Mine. Comparable results are obtained from the current model with a rock fragmentation factor α of 0.2 and a stress reduction factor β of 0.8. It is shown that a destress blasting with these parameters reduces the major principal stress in the nearest stopes by 10–25 MPa. This yields an immediate reduction of BSR, which is deemed sufficient to reduce volume of ore at risk in the pillar.

  19. The Psychiatric Genomics Consortium Posttraumatic Stress Disorder Workgroup: Posttraumatic Stress Disorder Enters the Age of Large-Scale Genomic Collaboration.

    Science.gov (United States)

    Logue, Mark W; Amstadter, Ananda B; Baker, Dewleen G; Duncan, Laramie; Koenen, Karestan C; Liberzon, Israel; Miller, Mark W; Morey, Rajendra A; Nievergelt, Caroline M; Ressler, Kerry J; Smith, Alicia K; Smoller, Jordan W; Stein, Murray B; Sumner, Jennifer A; Uddin, Monica

    2015-09-01

    The development of posttraumatic stress disorder (PTSD) is influenced by genetic factors. Although there have been some replicated candidates, the identification of risk variants for PTSD has lagged behind genetic research of other psychiatric disorders such as schizophrenia, autism, and bipolar disorder. Psychiatric genetics has moved beyond examination of specific candidate genes in favor of the genome-wide association study (GWAS) strategy of very large numbers of samples, which allows for the discovery of previously unsuspected genes and molecular pathways. The successes of genetic studies of schizophrenia and bipolar disorder have been aided by the formation of a large-scale GWAS consortium: the Psychiatric Genomics Consortium (PGC). In contrast, only a handful of GWAS of PTSD have appeared in the literature to date. Here we describe the formation of a group dedicated to large-scale study of PTSD genetics: the PGC-PTSD. The PGC-PTSD faces challenges related to the contingency on trauma exposure and the large degree of ancestral genetic diversity within and across participating studies. Using the PGC analysis pipeline supplemented by analyses tailored to address these challenges, we anticipate that our first large-scale GWAS of PTSD will comprise over 10 000 cases and 30 000 trauma-exposed controls. Following in the footsteps of our PGC forerunners, this collaboration-of a scope that is unprecedented in the field of traumatic stress-will lead the search for replicable genetic associations and new insights into the biological underpinnings of PTSD.

  20. COMPI Fertility Problem Stress Scales is a brief, valid and reliable tool for assessing stress in patients seeking treatment

    DEFF Research Database (Denmark)

    Sobral, Maria P.; Costa, Maria E.; Schmidt, Lone

    2017-01-01

    STUDY QUESTION Are the Copenhagen Multi‐Centre Psychosocial Infertility research program Fertility Problem Stress Scales (COMPI-FPSS) a reliable and valid measure across gender and culture? SUMMARY ANSWER The COMPI-FPSS is a valid and reliable measure, presenting excellent or good fit...... comparability of fertility-related stress across genders and countries. STUDY DESIGN SIZE, DURATION Cross-sectional study. First, we tested the structure of the COMPI-FPSS. Then, reliability and validity (convergent and discriminant) were examined for the final model. Finally, measurement invariance both across...... the validation of the COMPI-FPSS cannot be made regarding infertile individuals not seeking treatment, or non-European patients. This study did not investigate predictive validity, and hence the capability of this instrument in detecting changes in fertility-specific adjustment over time and predicting...

  1. Psychometric properties and factor structure of the Swedish version of the Perceived Stress Scale.

    Science.gov (United States)

    Eklund, Mona; Bäckström, Martin; Tuvesson, Hanna

    2014-10-01

    The Perceived Stress Scale (PSS) measures general stress and the Swedish version, although used in several studies, has not been extensively evaluated for psychometric properties. This study aimed to investigate psychometric properties and the factor solution of the Swedish 14-item version when used with two samples, namely a mixed Internet sample of women and men (n = 171) and another of women with stress-related disorders (n = 84). Classical test theory, including confirmatory factor analysis, was employed. The factor structure supported a two-factor model for the PSS and confirmed other language versions of the PSS, although one items showed a low item-total correlation. The PSS showed to be feasible with the investigated samples and the results indicated no ceiling or floor effects and good internal consistency of the PSS. Several aspects of construct validity were shown. An association of - 0.66 between the PSS and a measure of coping indicated good concurrent validity. Criterion validity was demonstrated through a statistically significant difference (P stress-related disorders and the Internet sample. Predictive validity of the PSS could be demonstrated in a short-term perspective. Based on the sample with stress-related disorders, sensitivity to change was shown through a statistically significant stress reduction (P stress-related disorders.

  2. Granular flow in pebble-bed nuclear reactors: Scaling, dust generation, and stress

    Energy Technology Data Exchange (ETDEWEB)

    Rycroft, Chris H., E-mail: chr@seas.harvard.edu [Department of Physics, University of California, Berkeley, CA 94720 (United States); Department of Mathematics, University of California, Berkeley, CA 94720 (United States); Department of Mathematics, Lawrence Berkeley Laboratory, Berkeley, CA 94720 (United States); School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States); Dehbi, Abdel, E-mail: abdel.dehbi@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Lind, Terttaliisa, E-mail: terttaliisa.lind@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Güntay, Salih, E-mail: salih.guentay@psi.ch [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2013-12-15

    Highlights: • The scaling properties of granular flow in pebble-bed reactors have been analyzed. • Simulations in a full-size reactor are compared to those scaled down by 3:1 and 6:1. • For some features, the scaled-down behavior is complex due to pebble packing effects. • Pebble stresses and dust generation due to pebble wear are analyzed in detail. • Approximate scaling laws for pebble stress and wear are developed. - Abstract: In experimental prototypes of pebble-bed reactors, significant quantities of graphite dust have been observed due to rubbing between pebbles as they flow through the core. At the typical operating conditions in these reactors, which feature high temperatures, pressures, and a helium atmosphere, limited data is available on the frictional properties of the pebble surfaces, and as a result, a conceptual design of a scaled-down version of a pebble-bed reactor has been proposed to investigate this issue in detail. However, this raises general questions about how the granular flow in a scaled facility will emulate that in a full-size reactor. To address this, simulations of granular flow in pebble-bed reactors using the discrete-element method (DEM) have been carried out in a full-size geometry (using 440,000 pebbles) and compared to those in geometries scaled down by factors of 3:1 and 6:1. Differences in velocity profiles, pebble ordering, pebble wear, and stresses are examined, and the effect of friction is discussed. The results show complex behavior due to discrete pebble packing effects, although several simple scaling rules can be derived.

  3. A Cross-Validation of the Keane and Penk MMPI Scales as Measures of Post-Traumatic Stress Disorder.

    Science.gov (United States)

    Watson, Charles G.; And Others

    1986-01-01

    Compared scores of post-traumatic stress disorder (PTSD) patients, psychiatric patients who did not meet PTSD criteria, and normals on the Keane et al PTSD scale and Penk Combat Scales for the Minnesota Multiphasic Personality Inventory. Results confirmed the validities of the PTSO scale and, to a lesser degree, Penk Combat Intensity Scales as…

  4. Short version of the Depression Anxiety Stress Scale-21: is it valid for Brazilian adolescents?

    Science.gov (United States)

    da Silva, Hítalo Andrade; dos Passos, Muana Hiandra Pereira; de Oliveira, Valéria Mayaly Alves; Palmeira, Aline Cabral; Pitangui, Ana Carolina Rodarti; de Araújo, Rodrigo Cappato

    2016-01-01

    ABSTRACT Objective To evaluate the interday reproducibility, agreement and validity of the construct of short version of the Depression Anxiety Stress Scale-21 applied to adolescents. Methods The sample consisted of adolescents of both sexes, aged between 10 and 19 years, who were recruited from schools and sports centers. The validity of the construct was performed by exploratory factor analysis, and reliability was calculated for each construct using the intraclass correlation coefficient, standard error of measurement and the minimum detectable change. Results The factor analysis combining the items corresponding to anxiety and stress in a single factor, and depression in a second factor, showed a better match of all 21 items, with higher factor loadings in their respective constructs. The reproducibility values for depression were intraclass correlation coefficient with 0.86, standard error of measurement with 0.80, and minimum detectable change with 2.22; and, for anxiety/stress: intraclass correlation coefficient with 0.82, standard error of measurement with 1.80, and minimum detectable change with 4.99. Conclusion The short version of the Depression Anxiety Stress Scale-21 showed excellent values of reliability, and strong internal consistency. The two-factor model with condensation of the constructs anxiety and stress in a single factor was the most acceptable for the adolescent population. PMID:28076595

  5. A global data set of soil hydraulic properties and sub-grid variability of soil water retention and hydraulic conductivity curves

    Science.gov (United States)

    Montzka, Carsten; Herbst, Michael; Weihermüller, Lutz; Verhoef, Anne; Vereecken, Harry

    2017-07-01

    Agroecosystem models, regional and global climate models, and numerical weather prediction models require adequate parameterization of soil hydraulic properties. These properties are fundamental for describing and predicting water and energy exchange processes at the transition zone between solid earth and atmosphere, and regulate evapotranspiration, infiltration and runoff generation. Hydraulic parameters describing the soil water retention (WRC) and hydraulic conductivity (HCC) curves are typically derived from soil texture via pedotransfer functions (PTFs). Resampling of those parameters for specific model grids is typically performed by different aggregation approaches such a spatial averaging and the use of dominant textural properties or soil classes. These aggregation approaches introduce uncertainty, bias and parameter inconsistencies throughout spatial scales due to nonlinear relationships between hydraulic parameters and soil texture. Therefore, we present a method to scale hydraulic parameters to individual model grids and provide a global data set that overcomes the mentioned problems. The approach is based on Miller-Miller scaling in the relaxed form by Warrick, that fits the parameters of the WRC through all sub-grid WRCs to provide an effective parameterization for the grid cell at model resolution; at the same time it preserves the information of sub-grid variability of the water retention curve by deriving local scaling parameters. Based on the Mualem-van Genuchten approach we also derive the unsaturated hydraulic conductivity from the water retention functions, thereby assuming that the local parameters are also valid for this function. In addition, via the Warrick scaling parameter λ, information on global sub-grid scaling variance is given that enables modellers to improve dynamical downscaling of (regional) climate models or to perturb hydraulic parameters for model ensemble output generation. The present analysis is based on the ROSETTA PTF

  6. A global data set of soil hydraulic properties and sub-grid variability of soil water retention and hydraulic conductivity curves

    Directory of Open Access Journals (Sweden)

    C. Montzka

    2017-07-01

    Full Text Available Agroecosystem models, regional and global climate models, and numerical weather prediction models require adequate parameterization of soil hydraulic properties. These properties are fundamental for describing and predicting water and energy exchange processes at the transition zone between solid earth and atmosphere, and regulate evapotranspiration, infiltration and runoff generation. Hydraulic parameters describing the soil water retention (WRC and hydraulic conductivity (HCC curves are typically derived from soil texture via pedotransfer functions (PTFs. Resampling of those parameters for specific model grids is typically performed by different aggregation approaches such a spatial averaging and the use of dominant textural properties or soil classes. These aggregation approaches introduce uncertainty, bias and parameter inconsistencies throughout spatial scales due to nonlinear relationships between hydraulic parameters and soil texture. Therefore, we present a method to scale hydraulic parameters to individual model grids and provide a global data set that overcomes the mentioned problems. The approach is based on Miller–Miller scaling in the relaxed form by Warrick, that fits the parameters of the WRC through all sub-grid WRCs to provide an effective parameterization for the grid cell at model resolution; at the same time it preserves the information of sub-grid variability of the water retention curve by deriving local scaling parameters. Based on the Mualem–van Genuchten approach we also derive the unsaturated hydraulic conductivity from the water retention functions, thereby assuming that the local parameters are also valid for this function. In addition, via the Warrick scaling parameter λ, information on global sub-grid scaling variance is given that enables modellers to improve dynamical downscaling of (regional climate models or to perturb hydraulic parameters for model ensemble output generation. The present analysis is based

  7. Assessment of a new self-rating scale for post-traumatic stress disorder.

    Science.gov (United States)

    Davidson, J R; Book, S W; Colket, J T; Tupler, L A; Roth, S; David, D; Hertzberg, M; Mellman, T; Beckham, J C; Smith, R D; Davison, R M; Katz, R; Feldman, M E

    1997-01-01

    In post-traumatic stress disorder (PTSD) there is a need for self-rating scales that are sensitive to treatment effects and have been tested in a broad range of trauma survivors. Separate measures of frequency and severity may also provide an advantage. Three hundred and fifty-three men and women completed the Davidson Trauma Scale (DTS), a 17-item scale measuring each DSM-IV symptom of PTSD on 5-point frequency and severity scales. These subjects comprised war veterans, survivors of rape or hurricane and a mixed trauma group participating in a clinical trial. Other scales were included as validity checks as follows: Global ratings, SCL-90-R, Eysenck Scale, Impact of Event Scale and Structured Clinical Interview for DSM-III-R. The scale demonstrated good test-retest reliability (r = 0.86), internal consistency (r = 0.99). One main factor emerged for severity and a smaller one for intrusion. In PTSD diagnosed subjects, and the factor structure more closely resembled the traditional grouping of symptoms. Concurrent validity was obtained against the SCID, with a diagnostic accuracy of 83% at a DTS score of 40. Good convergent and divergent validity was obtained. The DTS showed predictive validity against response to treatment, as well as being sensitive to treatment effects. The DTS showed good reliability and validity, and offers promised as a scale which is particularly suited to assessing symptom severity, treatment outcome and in screening for the likely diagnosis of PTSD.

  8. Autonomous Operation of Hybrid Microgrid with AC and DC Sub-Grids

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Blaabjerg, Frede

    2011-01-01

    This paper investigates on the active and reactive power sharing of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac sub-grids, interconnected by power electronic interfaces. The main challenge here is to manage...... the power flow among all the sources distributed throughout the two types of sub-grids, which certainly is tougher than previous efforts developed for only either ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc...... sources, ac sources and interlinking converters. Suitable control and normalization schemes are therefore developed for controlling them with results presented for showing the overall performance of the hybrid microgrid....

  9. Assessing Perceived Stress in Medical Personnel: In Search of an Appropriate Scale for the Bengali Population

    Science.gov (United States)

    Chakraborti, Amrita; Ray, Prasenjit; Sanyal, Debasish; Thakurta, Rajarshi Guha; Bhattacharayya, Amit K.; Mallick, Asim Kumar; Das, Ranjan; Ali, Syed Naiyer

    2013-01-01

    Background: The occurrence of stress and stress related anxiety and depression in medical personnel are being increasingly reported in literature. The perceived stress scale (PSS) is the most widely used psychological instrument for measuring the perception of stress. It is needed to assess perceived stress in our population using appropriately translated version of PSS. The objectives of study were to prepare a Bengali version of PSS-10 and to establish its psychometric properties in the study population. Materials and Methods: The study was conducted in a teaching hospital among medical students and interns (N=37). The translated Bengali version and the original English version of PSS-10 were separately handed over to the individual subjects. The scores were compared across different subgroups and psychometric properties of the translated version were assessed using SPSS 16. Results: Internal consistency of PSS English (α=0.79) and Bengali (α=0.80) was satisfactory. Intra-rater reliability was adequate (κ>0.5) for most of the items, but showed an inadequate value (κBengali version, a new six-item PSS in Bengali was derived that showed good internal consistency (α=0.699). Conclusion: This new version needs to be validated in a larger study population. Perceived stress score using PSS-10 was considerably high in our study population, although there was no significant difference between the subgroups (male/female, intern/student). PMID:23833339

  10. Reliability and validity of the Perceived Stress Scale-10 in Hispanic Americans with English or Spanish language preference.

    Science.gov (United States)

    Baik, Sharon H; Fox, Rina S; Mills, Sarah D; Roesch, Scott C; Sadler, Georgia Robins; Klonoff, Elizabeth A; Malcarne, Vanessa L

    2017-01-01

    This study examined the psychometric properties of the Perceived Stress Scale-10 among 436 community-dwelling Hispanic Americans with English or Spanish language preference. Multigroup confirmatory factor analysis examined the factorial invariance of the Perceived Stress Scale-10 across language groups. Results supported a two-factor model (negative, positive) with equivalent response patterns and item intercepts but different factor covariances across languages. Internal consistency reliability of the Perceived Stress Scale-10 total and subscale scores was good in both language groups. Convergent validity was supported by expected relationships of Perceived Stress Scale-10 scores to measures of anxiety and depression. These results support the use of the Perceived Stress Scale-10 among Hispanic Americans.

  11. Reliability, Validity and Psychometric Properties of the Greek Translation of the Posttraumatic Stress Disorder Scale.

    Science.gov (United States)

    Kontoangelos, Konstantinos; Tsiori, Sofia; Poulakou, Garyfalia; Protopapas, Konstantinos; Katsarolis, Ioannis; Sakka, Vissaria; Kavatha, Dimitra; Papadopoulos, Antonios; Antoniadou, Anastasia; Papageorgiou, Charalambos C

    2017-03-22

    The Greek version of the Davidson Trauma Scale (DTS) was developed to respond to the need of Greek-speaking individuals. The translated questionnaire was administered to 128 HIV outpatients (aged 37.1±9.1) and 166 control patients (aged 32.4±13.4). In addition to the DTS Greek scale, subjects were assessed with two other scales useful for assessing validity. For each factor analyses two components were extracted, based on Cattell's scree test. The two components solution accounted for 55.34% of the total variation in case of frequency variables and 61.45% in case of severity variables. The Cronbach's alpha coefficient and Guttman split-half coefficient of the DTS scale were 0.93 and 0.88 respectively. The test-retest reliability of the Greek version of DTS scale proved to be satisfactory. Individual items had good intra-class correlation coefficients higher than 0.5, which means that all questions have high levels of external validity. The psychometric strength of interview for posttraumatic stress disorder-Greek version it's reliable for its future use, particularly for screening subjects with possible diagnosis of posttraumatic stress disorder.

  12. Confirmatory Factor Analysis of the Perceived Stress Scale-4 in a Community Sample.

    Science.gov (United States)

    Ingram, Paul B; Clarke, Erik; Lichtenberg, James W

    2016-04-01

    Although the Perceived Stress Scale (PSS) is among the most widely used measures of perceived stress, it has only recently begun to be tested in independent psychometric validation studies, and the four-item version of the PSS (PSS-4) (the briefest version of this measure) has never undergone testing to examine and confirm the originally proposed structure. To address this paucity of research, the present study (a) tested the structure of the PSS-4 in the first confirmatory factor analysis of the instrument and (b) tested for item-level gender differences in the PSS that have been demonstrated in other versions of this scale. Results indicated that the PSS four-item measure does not fit its proposed model. Additionally, score differences were observed for one item across genders. Copyright © 2014 John Wiley & Sons, Ltd.

  13. Validation of the Perceived Stress Scale in a community sample of older adults.

    Science.gov (United States)

    Ezzati, Ali; Jiang, Julie; Katz, Mindy J; Sliwinski, Martin J; Zimmerman, Molly E; Lipton, Richard B

    2014-06-01

    Three versions of Perceived Stress Scale (PSS-14, PSS-10, and PSS-4) are among the most widely used measures of stress. The aim of the current study was to validate this instrument in a sample of nondemented older adults to facilitate studies of the impact of stress on health. Seven hundred sixty-eight nondemented adults over the age of 70 years completed the PSS-14 questionnaire and other neuropsychological tests. Exploratory factor analysis was used to determine the underlying factor structure of all PSS versions, and confirmatory factor analysis was used to test the construct validity of factors. The internal consistency reliability of the scales was assessed using Cronbach's alpha, and concurrent validity was evaluated by examining PSS relation with age, gender, depression, anxiety, and Positive Affect and Negative Affect Schedule. A two-factor model was the optimal fit for the 14-item and 10-item versions of PSS. For PSS-14, all items' loadings exceeded 0.4 for one of the two factors except item 12. Therefore, we studied a 13-item version of PSS and 10-item and 4-item subsets representing PSS-10 and PSS-4. Internal consistency coefficients were satisfactory for the full scale of PSS-13 and PSS-10 but not for PSS-4. Women reported higher levels of stress than men. Higher levels of total PSS scores showed association with higher levels of depression, anxiety, and negative affect, and lower level of positive affect. The 13-item and 10-item versions of PSS may be used to understand the experience of stress among older adults. Copyright © 2013 John Wiley & Sons, Ltd.

  14. Full-scale performance assessment of aircraft secondary sandwich structure using thermoelastic stress analysis

    OpenAIRE

    Crump, D.A.; Dulieu-Barton, J.M.; Savage, J

    2009-01-01

    The use of resin film infusion (RFI) has been proven to reduce the cost of production of aircraft secondary sandwich structure. In this paper thermoelastic stress analysis (TSA) is used to assess the performance of full scale aircraft sandwich structure panels produced using both the conventional autoclave process and RFI. Finite element (FE) models of both panel types are developed and TSA is used to validate the models.

  15. Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress.

    Science.gov (United States)

    Martin, Raleigh L; Kok, Jasper F

    2017-06-01

    Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation-the wind-driven transport of sand in hopping trajectories-scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces.

  16. Validation of Reef-Scale Thermal Stress Satellite Products for Coral Bleaching Monitoring

    Directory of Open Access Journals (Sweden)

    Scott F. Heron

    2016-01-01

    Full Text Available Satellite monitoring of thermal stress on coral reefs has become an essential component of reef management practice around the world. A recent development by the U.S. National Oceanic and Atmospheric Administration’s Coral Reef Watch (NOAA CRW program provides daily global monitoring at 5 km resolution—at or near the scale of most coral reefs. In this paper, we introduce two new monitoring products in the CRW Decision Support System for coral reef management: Regional Virtual Stations, a regional synthesis of thermal stress conditions, and Seven-day Sea Surface Temperature (SST Trend, describing recent changes in temperature at each location. We describe how these products provided information in support of management activities prior to, during and after the 2014 thermal stress event in the Commonwealth of the Northern Mariana Islands (CNMI. Using in situ survey data from this event, we undertake the first quantitative comparison between 5 km satellite monitoring products and coral bleaching observations. Analysis of coral community characteristics, historical temperature conditions and thermal stress revealed a strong influence of coral biodiversity in the patterns of observed bleaching. This resulted in a model based on thermal stress and generic richness that explained 97% of the variance in observed bleaching. These findings illustrate the importance of using local benthic characteristics to interpret the level of impact from thermal stress exposure. In an era of continuing climate change, accurate monitoring of thermal stress and prediction of coral bleaching are essential for stakeholders to direct resources to the most effective management actions to conserve coral reefs.

  17. Factor structure and validity of the Depression, Anxiety and Stress Scale-21 in Swedish translation.

    Science.gov (United States)

    Alfonsson, S; Wallin, E; Maathz, P

    2017-03-01

    WHAT IS KNOWN ON THE SUBJECT?: The Depression, Anxiety and Stress Scale-21 (DASS-21) is a widely used measurement for psychological symptoms and distress. Some previous studies have shown that the DASS-21 can accurately measure symptoms of anxiety, depression and stress, while other studies have indicated that the DASS-21 mainly measures overall distress. The factor structure of the DASS-21 is important and debated since if affects interpretations of findings. WHAT DOES THIS PAPER ADD TO EXISTING KNOWLEDGE?: In this study, the DASS-21 was translated into Swedish and evaluated in three diverse samples. The DASS-21 subscales of Depression and Anxiety correlated significantly with corresponding criteria instruments. The DASS-21 Stress subscale showed more diverse associations with psychological distress. The analyses supported a bifactor model of the DASS-21 with three specific factors of depression, anxiety and stress as well as a general distress factor. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: The results show that the DASS-21 may be used to measure unique symptoms of depression, anxiety and, with some caveat, stress as well as overall psychological distress. This study confirms that the DASS-21 is theoretically sound instrument that is feasible for both research and clinical practice. The DASS-21 can be an accessible tool for screening and evaluation in first-line mental health services. Introduction There is a constant need for theoretically sound and valid self-report instruments for measuring psychological distress. Previous studies have shown that the Depression, Anxiety and Stress Scale-21 (DASS-21) is theoretically sound, but there have been some inconsistent results regarding its factor structure. Aims The aim of the present study was to investigate and elucidate the factor structure and convergent validity of the DASS-21. Methods A total of 624 participants recruited from student, primary care and psychotherapy populations. The factor structure of the DASS

  18. Genome-scale cold stress response regulatory networks in ten Arabidopsis thaliana ecotypes

    Science.gov (United States)

    2013-01-01

    Background Low temperature leads to major crop losses every year. Although several studies have been conducted focusing on diversity of cold tolerance level in multiple phenotypically divergent Arabidopsis thaliana (A. thaliana) ecotypes, genome-scale molecular understanding is still lacking. Results In this study, we report genome-scale transcript response diversity of 10 A. thaliana ecotypes originating from different geographical locations to non-freezing cold stress (10°C). To analyze the transcriptional response diversity, we initially compared transcriptome changes in all 10 ecotypes using Arabidopsis NimbleGen ATH6 microarrays. In total 6061 transcripts were significantly cold regulated (p cold stress regulon genes. Significant numbers of non-synonymous amino acid changes were observed in the coding region of the CBF regulon genes. Considering the limited knowledge about regulatory interactions between transcription factors and their target genes in the model plant A. thaliana, we have adopted a powerful systems genetics approach- Network Component Analysis (NCA) to construct an in-silico transcriptional regulatory network model during response to cold stress. The resulting regulatory network contained 1,275 nodes and 7,720 connections, with 178 transcription factors and 1,331 target genes. Conclusions A. thaliana ecotypes exhibit considerable variation in transcriptome level responses to non-freezing cold stress treatment. Ecotype specific transcripts and related gene ontology (GO) categories were identified to delineate natural variation of cold stress regulated differential gene expression in the model plant A. thaliana. The predicted regulatory network model was able to identify new ecotype specific transcription factors and their regulatory interactions, which might be crucial for their local geographic adaptation to cold temperature. Additionally, since the approach presented here is general, it could be adapted to study networks regulating

  19. Validity of the Depression Anxiety Stress Scales in assessing depression and anxiety following traumatic brain injury.

    Science.gov (United States)

    Dahm, Jane; Wong, Dana; Ponsford, Jennie

    2013-10-01

    Anxiety and depression following traumatic brain injury (TBI) are associated with poorer outcomes. A brief self-report questionnaire would assist in identifying those at risk, however validity of such measures is complicated by confounding symptoms of the injury. This study investigated the validity of the Depression Anxiety Stress Scales (DASS) and Hospital Anxiety and Depression Scale (HADS), in screening for clinical diagnoses of anxiety and mood disorders following TBI. One hundred and twenty-three participants with mild to severe TBI were interviewed using the SCID (Axis I) and completed the DASS and HADS. The DASS, DASS21 and HADS scales demonstrated validity compared with SCID diagnoses of anxiety and mood disorders as measured by Area Under ROC Curve, sensitivity and specificity. Validity of the DASS depression scale benefited from items reflecting symptoms of devaluation of life, self-deprecation, and hopelessness that are not present on the HADS. Validity of the HADS anxiety scale benefited from items reflecting symptoms of tension and worry that are measured separately for the DASS on the stress scale. Participants were predominantly drawn from a rehabilitation centre which may limit the extent to which results can be generalized. Scores for the DASS21 were derived from the DASS rather than being administered separately. The DASS, DASS21 and HADS demonstrated validity as screening measures of anxiety and mood disorders in this TBI sample. The findings support use of these self-report questionnaires for individuals with TBI to identify those who should be referred for clinical diagnostic follow-up. © 2013 Elsevier B.V. All rights reserved.

  20. Rasch model analysis of the Depression, Anxiety and Stress Scales (DASS

    Directory of Open Access Journals (Sweden)

    Tennant Alan

    2009-05-01

    Full Text Available Abstract Background There is a growing awareness of the need for easily administered, psychometrically sound screening tools to identify individuals with elevated levels of psychological distress. Although support has been found for the psychometric properties of the Depression, Anxiety and Stress Scales (DASS using classical test theory approaches it has not been subjected to Rasch analysis. The aim of this study was to use Rasch analysis to assess the psychometric properties of the DASS-21 scales, using two different administration modes. Methods The DASS-21 was administered to 420 participants with half the sample responding to a web-based version and the other half completing a traditional pencil-and-paper version. Conformity of DASS-21 scales to a Rasch partial credit model was assessed using the RUMM2020 software. Results To achieve adequate model fit it was necessary to remove one item from each of the DASS-21 subscales. The reduced scales showed adequate internal consistency reliability, unidimensionality and freedom from differential item functioning for sex, age and mode of administration. Analysis of all DASS-21 items combined did not support its use as a measure of general psychological distress. A scale combining the anxiety and stress items showed satisfactory fit to the Rasch model after removal of three items. Conclusion The results provide support for the measurement properties, internal consistency reliability, and unidimensionality of three slightly modified DASS-21 scales, across two different administration methods. The further use of Rasch analysis on the DASS-21 in larger and broader samples is recommended to confirm the findings of the current study.

  1. Clinical validity of a relocation stress scale for the families of patients transferred from intensive care units.

    Science.gov (United States)

    Oh, HyunSoo; Lee, Seul; Kim, JiSun; Lee, EunJu; Min, HyoNam; Cho, OkJa; Seo, WhaSook

    2015-07-01

    This study was conducted to develop a family relocation stress scale by modifying the Son's Relocation Stress Syndrome Scale, to examine its clinical validity and reliability and to confirm its suitability for measuring family relocation stress. The transfer of ICU patients to general wards is a significant anxiety-producing event for family members. However, no relocation stress scale has been developed specifically for families. A nonexperimental, correlation design was adopted. The study subjects were 95 family members of 95 ICU patients at a university hospital located in Incheon, South Korea. Face and construct validities of the devised family relocation stress scale were examined. Construct validity was examined using factor analysis and by using a nomological validity test. Reliability was also examined. Face and content validity of the scale were verified by confirming that its items adequately measured family relocation stress. Factor analysis yielded four components, and the total variance explained by these four components was 63·0%, which is acceptable. Nomological validity was well supported by significant relationships between relocation stress and degree of preparation for relocation, patient self-care ability, family burden and satisfaction with the relocation process. The devised scale was also found to have good reliability. The family relocation stress scale devised in this study was found to have good validity and reliability, and thus, is believed to offer a means of assessing family relocation stress. The findings of this study provide a reliable and valid assessment tool when nurses prepare families for patient transfer from an ICU to a ward setting, and may also provide useful information to those developing an intervention programme for family relocation stress management. © 2015 John Wiley & Sons Ltd.

  2. Laue-DIC: a new method for improved stress field measurements at the micrometer scale.

    Science.gov (United States)

    Petit, J; Castelnau, O; Bornert, M; Zhang, F G; Hofmann, F; Korsunsky, A M; Faurie, D; Le Bourlot, C; Micha, J S; Robach, O; Ulrich, O

    2015-07-01

    A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10(-5).

  3. Reynolds stress scaling in pipe flow turbulence—first results from CICLoPE

    Science.gov (United States)

    Örlü, R.; Fiorini, T.; Segalini, A.; Bellani, G.; Talamelli, A.; Alfredsson, P. H.

    2017-03-01

    This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×104 are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend-Perry constant of A2≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend-Perry constant, i.e. A2,w≈A2/2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities.

  4. The Femininity Ideology Scale (FIS): dimensions and its relationship to anxiety and feminine gender role stress.

    Science.gov (United States)

    Richmond, Katherine; Levant, Ronald; Smalley, Bryant; Cook, Stephen

    2015-01-01

    The purpose of this study was to conduct a confirmatory factor analytic investigation of the Femininity Ideology Scale (FIS) and to assess whether feminine gender role stress mediated the relationship between femininity ideology and anxiety. During the 2010-2011 academic year, a convenience sample of 606 college women were recruited from three universities and one college. Confirmatory factor analysis supported a four- versus the hypothesized five-factor model, resulting in the elimination of the Dependency/Deference factor. Mediation analysis using structural equation modeling indicated no direct relationship between Femininity Ideology and Anxiety, although an indirect one was observed, mediated through Feminine Gender Role Stress. The results are discussed in terms of possible changes in contemporary notions of femininity, and the utility of using the FIS in applied therapeutic settings.

  5. Numerical Dissipation and Subgrid Scale Modeling for Separated Flows at Moderate Reynolds Numbers

    Science.gov (United States)

    Cadieux, Francois; Domaradzki, Julian Andrzej

    2014-11-01

    Flows in rotating machinery, for unmanned and micro aerial vehicles, wind turbines, and propellers consist of different flow regimes. First, a laminar boundary layer is followed by a laminar separation bubble with a shear layer on top of it that experiences transition to turbulence. The separated turbulent flow then reattaches and evolves downstream from a nonequilibrium turbulent boundary layer to an equilibrium one. In previous work, the capability of LES to reduce the resolution requirements down to 1 % of DNS resolution for such flows was demonstrated (Cadieux et al., JFE 136-6). However, under-resolved DNS agreed better with the benchmark DNS than simulations with explicit SGS modeling because numerical dissipation and filtering alone acted as a surrogate SGS dissipation. In the present work numerical viscosity is quantified using a new method proposed recently by Schranner et al. and its effects are analyzed and compared to turbulent eddy viscosities of explicit SGS models. The effect of different SGS models on a simulation of the same flow using a non-dissipative code is also explored. Supported by NSF.

  6. Accounting for subgrid scale topographic variations in flood propagation modeling using MODFLOW

    DEFF Research Database (Denmark)

    Milzow, Christian; Kinzelbach, W.

    2010-01-01

    To be computationally viable, grid-based spatially distributed hydrological models of large wetlands or floodplains must be set up using relatively large cells (order of hundreds of meters to kilometers). Computational costs are especially high when considering the numerous model runs or model time...

  7. Final Report: Systematic Development of a Subgrid Scaling Framework to Improve Land Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Dickinson, Robert Earl [Univ. of Texas, Austin, TX (United States)

    2016-07-11

    We carried out research to development improvements of the land component of climate models and to understand the role of land in climate variability and change. A highlight was the development of a 3D canopy radiation model. More than a dozen publications resulted.

  8. Are happier people less vulnerable to rumination, anxiety, and post-traumatic stress? Evidence from a large scale disaster

    National Research Council Canada - National Science Library

    Zanon, Cristian; Hutz, Claudio S; Reppold, Caroline T; Zenger, Markus

    2016-01-01

    The present longitudinal study tested hypotheses about the relationship of subjective well-being and neuroticism with rumination, anxiety, and post-traumatic stress in university students after a large scale disaster...

  9. The assessment of parental stress and support in the neonatal intensive care unit using the Parent Stress Scale - Neonatal Intensive Care Unit.

    Science.gov (United States)

    Turner, Melanie; Chur-Hansen, Anna; Winefield, Helen; Stanners, Melinda

    2015-09-01

    Parental stress in the neonatal intensive care unit (NICU) has been reported, however identifying modifiable stress factors and looking for demographic parent factors related to stress has not been well researched. This study aims to identify the most stressful elements for parents in the neonatal intensive care unit. Parents of babies in an Australian neonatal intensive care unit (N=73) completed both the Parent Stress Scale - Neonatal Intensive Care Unit and a survey of parent and baby demographic and support experience variables (Parent Survey) over an 18-month period. Older parental age, very premature birth and twin birth were significantly associated with a higher Parent Stress Scale - Neonatal Intensive Care Unit score. Having a high score in the Relationship and Parental Role scale was strongly associated with attendance at the parent support group. These results indicate the variables associated with stress and this knowledge can be used by teams within hospitals to provide better supportive emotional care for parents. Copyright © 2015 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  10. Short version of the Depression Anxiety Stress Scale-21: is it valid for Brazilian adolescents?

    Science.gov (United States)

    Silva, Hítalo Andrade da; Passos, Muana Hiandra Pereira Dos; Oliveira, Valéria Mayaly Alves de; Palmeira, Aline Cabral; Pitangui, Ana Carolina Rodarti; Araújo, Rodrigo Cappato de

    2016-01-01

    To evaluate the interday reproducibility, agreement and validity of the construct of short version of the Depression Anxiety Stress Scale-21 applied to adolescents. The sample consisted of adolescents of both sexes, aged between 10 and 19 years, who were recruited from schools and sports centers. The validity of the construct was performed by exploratory factor analysis, and reliability was calculated for each construct using the intraclass correlation coefficient, standard error of measurement and the minimum detectable change. The factor analysis combining the items corresponding to anxiety and stress in a single factor, and depression in a second factor, showed a better match of all 21 items, with higher factor loadings in their respective constructs. The reproducibility values for depression were intraclass correlation coefficient with 0.86, standard error of measurement with 0.80, and minimum detectable change with 2.22; and, for anxiety/stress: intraclass correlation coefficient with 0.82, standard error of measurement with 1.80, and minimum detectable change with 4.99. The short version of the Depression Anxiety Stress Scale-21 showed excellent values of reliability, and strong internal consistency. The two-factor model with condensation of the constructs anxiety and stress in a single factor was the most acceptable for the adolescent population. Avaliar a reprodutibilidade interdias, a concordância e a validade do construto da versão reduzida da Depression Anxiety Stress Scale-21 aplicada a adolescentes. A amostra foi composta por adolescentes de ambos os sexos, com idades entre 10 e 19 anos, recrutados de escolas e centros esportivos. A validade de construto foi realizada por análise fatorial exploratória, e a confiabilidade foi calculada para cada construto, por meio de coeficiente de correlação intraclasse, erro padrão de medida e mudança mínima detectável. A análise fatorial combinando os itens correspondentes a ansiedade e estresse em um

  11. Association of perceived stress with stressful life events, lifestyle and sociodemographic factors: a large-scale community-based study using logistic quantile regression.

    Science.gov (United States)

    Feizi, Awat; Aliyari, Roqayeh; Roohafza, Hamidreza

    2012-01-01

    The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent), variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors' effects heterogeneity depending on individual location on the distribution of perceived stress. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender's coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people.

  12. Association of Perceived Stress with Stressful Life Events, Lifestyle and Sociodemographic Factors: A Large-Scale Community-Based Study Using Logistic Quantile Regression

    Science.gov (United States)

    Feizi, Awat; Aliyari, Roqayeh; Roohafza, Hamidreza

    2012-01-01

    Objective. The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. Methods. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent), variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors' effects heterogeneity depending on individual location on the distribution of perceived stress. Results. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender's coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. Conclusions. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people. PMID:23091560

  13. Association of Perceived Stress with Stressful Life Events, Lifestyle and Sociodemographic Factors: A Large-Scale Community-Based Study Using Logistic Quantile Regression

    Directory of Open Access Journals (Sweden)

    Awat Feizi

    2012-01-01

    Full Text Available Objective. The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. Methods. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent, variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors’ effects heterogeneity depending on individual location on the distribution of perceived stress. Results. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender’s coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. Conclusions. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people.

  14. Validity and reliability of the Cohen 10-item Perceived Stress Scale in patients with chronic headache: Persian version.

    Science.gov (United States)

    Khalili, Robabe; Sirati Nir, Masoud; Ebadi, Abbas; Tavallai, Abbas; Habibi, Mehdi

    2017-04-01

    The Cohen Perceived Stress Scale is being used widely in various countries. The present study evaluated the validity and reliability of the Cohen 10-item Perceived Stress Scale (PSS-10) in assessing tension headache, migraine, and stress-related diseases in Iran. This study is a methodological and cross-sectional descriptive investigation of 100 patients with chronic headache admitted to the pain clinic of Baqiyatallah Educational and Therapeutic Center. Convenience sampling was used for subject selection. PSS psychometric properties were evaluated in two stages. First, the standard scale was translated. Then, the face validity, content, and construct of the translated version were determined. The average age of participants was 38 years with a standard deviation (SD) of 13.2. As for stress levels, 12% were within the normal range, 36% had an intermediate level, and 52% had a high level of stress. The face validity and scale content were remarkable, and the KMO coefficient was 0.82. Bartlett's test yielded 0.327 which was statistically significant (pfactor analysis of the scale, the two elements of "coping" and "distress" were determined. A Cronbach's Alpha coefficient of 0.72 was obtained. This confirmed the remarkable internal consistency and stability of the scale through repeated measure tests (0.93). The Persian PSS-10 has good internal consistency and reliability. The availability of a validated Persian PSS-10 would indicate a link between stress and chronic headache. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Development and validation of the Acculturative Stress Scale for Chinese College Students in the United States (ASSCS).

    Science.gov (United States)

    Bai, Jieru

    2016-04-01

    Chinese students are the biggest ethnic group of international students in the United States. This study aims to develop a reliable and valid scale to accurately measure their acculturative stress. A 72-item pool was sent online to Chinese students and a five-factor scale of 32 items was generated by exploratory factor analysis. The five factors included language insufficiency, social isolation, perceived discrimination, academic pressure, and guilt toward family. The Acculturative Stress Scale for Chinese Students demonstrated high reliability and initial validity by predicting depression and life satisfaction. It was the first Chinese scale of acculturative stress developed and validated among a Chinese student sample in the United States. In the future, the scale can be used as a diagnostic tool by mental health professionals and a self-assessment tool by Chinese students. (c) 2016 APA, all rights reserved.

  16. Evaluation of a Sub-Grid Topographic Drag Parameterizations for Modeling Surface Wind Speed During Storms Over Complex Terrain in the Northeast U.S.

    Science.gov (United States)

    Frediani, M. E.; Hacker, J.; Anagnostou, E. N.; Hopson, T. M.

    2015-12-01

    This study aims at improving regional simulation of 10-meter wind speed by verifying PBL schemes for storms at different scales, including convective storms, blizzards, tropical storms and nor'easters over complex terrain in the northeast U.S. We verify a recently proposed sub-grid topographic drag scheme in stormy conditions and compare it with two PBL schemes (Mellor-Yamada and Yonsei University) from WRF-ARW over a region in the Northeast U.S. The scheme was designed to adjust the surface drag over regions with high subgrid-scale topographic variability. The schemes are compared using spatial, temporal, and pattern criteria against surface observations. The spatial and temporal criteria are defined by season, diurnal cycle, and topography; the pattern, is based on clusters derived using clustering analysis. Results show that the drag scheme reduces the positive bias of low wind speeds, but over-corrects the high wind speeds producing a magnitude-increasing negative bias with increasing speed. Both other schemes underestimate the most frequent low-speed mode and overestimate the high-speeds. Error characteristics of all schemes respond to seasonal and diurnal cycle changes. The Topo-wind experiment shows the best agreement with the observation quantiles in summer and fall, the best representation of the diurnal cycle in these seasons, and reduces the bias of all surface stations near the coast. In more stable conditions the Topo-wind scheme shows a larger negative bias. The cluster analysis reveals a correlation between bias and mean speed from the Mellor-Yamada and Yonsei University schemes that is not present when the drag scheme is used. When the drag scheme is used the bias correlates with wind direction; the bias increases when the meridional wind component is negative. This pattern corresponds to trajectories with more land interaction with the highest biases found in northwest circulation clusters.

  17. Development and validation of a Thai stressful life events rating scale for patients with a diagnosis of schizophrenic methamphetamine abuse

    Directory of Open Access Journals (Sweden)

    Ek-uma Imkome

    2017-04-01

    Full Text Available This study aimed to psychometrically test a Thai Stressful Life Events Rating Scale (TSLERS. Factor analysis was done on data collected from 313 patients with schizophrenia and methamphetamine abuse in Thailand from April to May, 2015. Results identified the following problems impacting physical and mental health: social relationship and social concerns, money, family life, life security, and career. Evaluation of the psychometric scale properties demonstrated acceptable validity and reliability. TSLERS provided scientific and empirical data about stressful life events of patients with schizophrenia and methamphetamine abuse, and was suitable for stress detection and suggesting further innovations.

  18. Stress polishing of E-ELT segment at LAM: full-scale demonstrator status

    Science.gov (United States)

    Laslandes, Marie; Rousselet, Nicolas; Ferrari, Marc; Hugot, Emmanuel; Floriot, Johan; Vivès, Sébastien; Lemaitre, Gérard; Carré, Jean François; Cayrel, Marc

    2011-10-01

    The Laboratoire d'Astrophysique de Marseille (LAM) is involved in the prototyping of a full scale demonstrator for stress polishing of segments for the European Extremely Large Telescope (E-ELT). Stress polishing method is developed at LAM since more than 40 years, and this mature technology has recently been used with success for VLT instruments. Stress polishing is now considered as a promising manufacturing method for mass production of large off axis mirrors, specifically for ELT segments. This powerful method, based on elasticity theory, allows the generation of super-smooth off-axis aspherics with a minimal amount of high spatial frequency ripples by spherically polishing a warped blank with a full-sized tool. Thanks to the simple spherical polishing, the operation time can be strongly reduced compared to the time-consuming sub-aperture tool methods of grinding and polishing. The goal is to rapidly converge to less than 1 micron RMS of optical quality on a circular blank which will be finally cut hexagonally and finished using Ion Beam Finishing. In this paper we will present the status of the demonstrator and the design of the warping harness prototype that must be able to precisely warp the circular blank.

  19. Psychometric properties of the Chinese version of the Perceived Stress Scale in policewomen.

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    Full Text Available BACKGROUND: The 10-item Perceived Stress Scale (PSS-10 is one of most widely used instruments to measure a global level of perceived stress in a range of clinical and research settings. This study was conducted to examine the psychometric properties of the Simplified Chinese version of the PSS-10 in policewomen. METHODOLOGY: A total of 240 policewomen were recruited in this study. The Simplified Chinese versions of the PSS-10, the Beck Depression Inventory Revised (BDI-II, and the Beck Anxiety Inventory (BAI were administered to all participants, and 36 of the participants were re-tested two weeks after the initial testing. PRINCIPAL FINDINGS: The overall Cronbach's alpha was 0.86, and the test-retest reliability coefficient was 0.68. Exploratory Factor Analysis (EFA yielded 2 factors with eigenvalues of 4.76 and 1.48, accounting for 62.41% of variance. Factor 1 consisted of 6 items representing "negative feelings"; whereas Factor 2 consisted of 4 items representing "positive feelings". The item loadings ranged from 0.72 to 0.83. The Confirmatory factor analysis (CFA indicated a very good fit of this two-factor model to this sample. The PSS-10 significantly correlated with both BDI-II and BAI, indicating an acceptable concurrent validity. CONCLUSIONS: The Simplified Chinese version of the PSS-10 demonstrated adequate psychometric properties for evaluating stress levels. The results support its use among the Chinese population.

  20. EXPLORING PHYSICIANS' DISSATISFACTION AND WORK-RELATED STRESS: DEVELOPMENT OF THE PhyDis SCALE

    Directory of Open Access Journals (Sweden)

    Monica Pedrazza

    2016-08-01

    Full Text Available Research, all over the world, is starting to recognize the potential impact of physicians’ dissatisfaction and burnout on their productivity, that is, on their intent to leave the job, on their work ability, on the amount of sick leave days, on their intent to continue practicing, and last but not least, on the quality of the services provided, which is an essential part of the general medical care system. It was interest of the provincial medical board’s ethical committee to acquire information about physician’s work-related stress and dissatisfaction. The research group was committed to define the indicators of dissatisfaction and work-related stressors. Focus groups were carried out, 21 stressful experience’s indicators were identified; we developed an online questionnaire to assess the amount of perceived stress relating to each indicator at work (3070 physicians were contacted by e-mail; quantitative and qualitative data analysis were carried out. The grounded theory perspective was applied in order to assure the most reliable procedure to investigate the concepts’ structure of work-related stress. We tested the five dimensions' model of the stressful experience with a confirmatory factor analysis: Personal Costs; Decline in Public Image and Role Uncertainty; Physician's Responsibility toward hopelessly ill Patients; Relationship with Staff and Colleagues; Bureaucracy. We split the sample according to attachment style (secure and insecure -anxious and avoidant-. Results show the complex representation of physicians’ dissatisfaction at work also with references to the variable of individual difference of attachment security/insecurity. The discriminant validity of the scale was tested. The original contribution of this paper lies on the one hand in the qualitative in depth inductive analysis of physicians’ dissatisfaction starting from physicians’ perception, on the other hand, it represents the first attempt to analyze the

  1. Exploring Physicians' Dissatisfaction and Work-Related Stress: Development of the PhyDis Scale.

    Science.gov (United States)

    Pedrazza, Monica; Berlanda, Sabrina; Trifiletti, Elena; Bressan, Franco

    2016-01-01

    Research, all over the world, is starting to recognize the potential impact of physicians' dissatisfaction and burnout on their productivity, that is, on their intent to leave the job, on their work ability, on the amount of sick leave days, on their intent to continue practicing, and last but not least, on the quality of the services provided, which is an essential part of the general medical care system. It was interest of the provincial medical board's ethical committee to acquire information about physician's work-related stress and dissatisfaction. The research group was committed to define the indicators of dissatisfaction and work-related stressors. Focus groups were carried out, 21 stressful experience's indicators were identified; we developed an online questionnaire to assess the amount of perceived stress relating to each indicator at work (3070 physicians were contacted by e-mail); quantitative and qualitative data analysis were carried out. The grounded theory perspective was applied in order to assure the most reliable procedure to investigate the concepts' structure of "work-related stress." We tested the five dimensions' model of the stressful experience with a confirmatory factor analysis: Personal Costs; Decline in Public Image and Role Uncertainty; Physician's Responsibility toward hopelessly ill Patients; Relationship with Staff and Colleagues; Bureaucracy. We split the sample according to attachment style (secure and insecure -anxious and avoidant-). Results show the complex representation of physicians' dissatisfaction at work also with references to the variable of individual difference of attachment security/insecurity. The discriminant validity of the scale was tested. The original contribution of this paper lies on the one hand in the qualitative in depth inductive analysis of physicians' dissatisfaction starting from physicians' perception, on the other hand, it represents the first attempt to analyze the physicians' dissatisfaction with

  2. [Organizational well-being and work-related stress in health care organizations: validation of the Work-related Stress Assessment Scale].

    Science.gov (United States)

    Coluccia, Anna; Lorini, Francesca; Ferretti, Fabio; Pozza, Andrea; Gaetani, Marco

    2015-01-01

    The issue of the assessment of work-related stress has stimulated in recent years, the production of several theoretical paradigms and assessment tools. In this paper we present a new scale for the assessment of organizational well-being and work-related stress specific for healthcare organizations (Work-related Stress Assessment Scale - WSAS). The goal of the authors is to examine the psychometric properties of the scale, so that it can be used in the healthcare setting as a work-related stress assessment tool. The answers of 230 healthcare professionals belonging to different roles have been analyzed. The study was realized in 16 Units of the University Hospital "S. Maria alle Scotte "of Siena. The exploratory factor analysis (EFA) revealed the presence of five factors with good internal consistency and reliability, "relationship to the structure of proximity" (α = 0.93) "change" (α = 0.92), "organization of work "(α = 0.81)," relationship with the company / Governance "(α = 0.87)" working environment "(α = 0.83). The analysis of SEM (Structural Equation Models) has confirmed the goodness of the factor solution (NNFI = 0.835, CFI = 0.921, RMSEA = 0.060). The good psychometric qualities, the shortness and simplicity of the scale WSAS makes it a useful aid in the assessment of work-related stress in health care organizations.

  3. Laue-DIC: a new method for improved stress field measurements at the micrometer scale

    Energy Technology Data Exchange (ETDEWEB)

    Petit, J., E-mail: johannpetit@u-paris10.fr [LEME, Université Paris Ouest, 50 rue de Sèvres, F-92410 Ville d’Avray (France); Castelnau, O. [PIMM, CNRS, Arts and Métiers ParisTech, 151 Bd de l’Hopital, F-75013 Paris (France); Bornert, M. [Laboratoire Navier, Université Paris-Est, École des Ponts ParisTech, F-77455 Marne-la-Vallée (France); Zhang, F. G. [PIMM, CNRS, Arts and Métiers ParisTech, 151 Bd de l’Hopital, F-75013 Paris (France); Hofmann, F.; Korsunsky, A. M. [Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ (United Kingdom); Faurie, D. [LSPM, CNRS, Université Paris 13, 93430 Villetaneuse (France); Le Bourlot, C. [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Micha, J. S. [Université Grenoble Alpes, INAC-SPrAM, F-38000 Grenoble (France); CNRS, SPrAM, F-38000 Grenoble (France); CRG-IF BM32 at ESRF, 71 Avenue des Martyrs, F-38000 Grenoble (France); Robach, O.; Ulrich, O. [Université Grenoble Alpes, INAC-SPrAM, F-38000 Grenoble (France); CRG-IF BM32 at ESRF, 71 Avenue des Martyrs, F-38000 Grenoble (France); CEA, INAC-SP2M, F-38000 Grenoble (France)

    2015-05-09

    The increment of elastic strain distribution, with a micrometer spatial resolution, is obtained by the correlation of successive Laue images. Application to a bent Si crystal allows evaluation of the accuracy of this new Laue-DIC method, which is about 10{sup −5}. A better understanding of the effective mechanical behavior of polycrystalline materials requires an accurate knowledge of the behavior at a scale smaller than the grain size. The X-ray Laue microdiffraction technique available at beamline BM32 at the European Synchrotron Radiation Facility is ideally suited for probing elastic strains (and associated stresses) in deformed polycrystalline materials with a spatial resolution smaller than a micrometer. However, the standard technique used to evaluate local stresses from the distortion of Laue patterns lacks accuracy for many micromechanical applications, mostly due to (i) the fitting of Laue spots by analytical functions, and (ii) the necessary comparison of the measured pattern with the theoretical one from an unstrained reference specimen. In the present paper, a new method for the analysis of Laue images is presented. A Digital Image Correlation (DIC) technique, which is essentially insensitive to the shape of Laue spots, is applied to measure the relative distortion of Laue patterns acquired at two different positions on the specimen. The new method is tested on an in situ deformed Si single-crystal, for which the prescribed stress distribution has been calculated by finite-element analysis. It is shown that the new Laue-DIC method allows determination of local stresses with a strain resolution of the order of 10{sup −5}.

  4. Reynolds stress scaling in pipe flow turbulence-first results from CICLoPE.

    Science.gov (United States)

    Örlü, R; Fiorini, T; Segalini, A; Bellani, G; Talamelli, A; Alfredsson, P H

    2017-03-13

    This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×10(4) are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend-Perry constant of A2≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend-Perry constant, i.e. A2,w≈A2/2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

  5. Development of short questionnaire to measure an extended set of role expectation conflict, coworker support and work-life balance: The new job stress scale

    Directory of Open Access Journals (Sweden)

    Abhishek Shukla

    2016-12-01

    Full Text Available This study aimed to investigate the reliability and validity of a new version of job stress scale, which measures the extended set of psychosocial stressors by adding new scales to the current version of the job stress scale. Additional scales were extensively collected from theoretical job stress models and similar questionnaire from different countries. Items were tested in workplace and refined through a pilot survey (n = 400 to examine the reliability and construct validity. Most scales showed acceptable levels of internal consistency, intra-class reliability, and test–retest reliability. Factor analysis and correlation analysis showed that these scales fit the theoretical expectations. These findings provided enough evidences that the new job stress scale is reliable and valid. Although confirmatory analysis should be examined in future studies. The new job stress scale is a useful instrument for organization and academicians to evaluate job stress in modern Indian workplace.

  6. Higher stress scores for female medical students measured by the Kessler Psychological Distress Scale (K10 in Pakistan

    Directory of Open Access Journals (Sweden)

    Khadija Qamar

    2014-10-01

    Full Text Available The aim of this study was to determine the stress level of medical students and the relationship between stress and academic year. A cross-sectional, descriptive study was conducted at an undergraduate medical school with a five-year curriculum, in Pakistan, from January 2014 to April 2014. Medical students in the first four years were included in the study. The Kessler Psychological Distress Scale (K10, a self-administered questionnaire, was distributed to the students. A total of 445 medical students completed the questionnaire. The average stress score was 19.61 (SD = 6.76 with a range from 10 to 43. Stress was experienced by 169 students (41.7%. The scores of female students were higher than scores of males, indicating a higher stress level (P = 0.011. The relationship between stress and academic year was insignificant (P = 0.392.

  7. Higher stress scores for female medical students measured by the Kessler Psychological Distress Scale (K10) in Pakistan.

    Science.gov (United States)

    Qamar, Khadija; Kiani, Muhammad Rizwan Bash; Ayyub, Aisha; Khan, Atif Ahmed; Osama, Mohammad

    2014-01-01

    The aim of this study was to determine the stress level of medical students and the relationship between stress and academic year. A cross-sectional, descriptive study was conducted at an undergraduate medical school with a five-year curriculum, in Pakistan, from January 2014 to April 2014. Medical students in the first four years were included in the study. The Kessler Psychological Distress Scale (K10), a self-administered questionnaire, was distributed to the students. A total of 445 medical students completed the questionnaire. The average stress score was 19.61 (SD=6.76) with a range from 10 to 43. Stress was experienced by 169 students (41.7%). The scores of female students were higher than scores of males, indicating a higher stress level (P=0.011). The relationship between stress and academic year was insignificant (P=0.392).

  8. Validity and Reliability of the Turkish Version of the DSM-5 Posttraumatic Stress Symptom Severity Scale-Child Form.

    Science.gov (United States)

    Yalin Sapmaz, Şermin; Ergin, Dilek; Özek Erkuran, Handan; Şen Celasin, Nesrin; Öztürk, Masum; Karaarslan, Duygu; Köroğlu, Ertuğrul; Aydemir, Ömer

    2017-09-01

    This study assessed the validity and reliability of the Turkish version of the DSM-5 Posttraumatic Stress Symptom Severity Scale-Child Form for use among the Turkish population. The study group consisted of 30 patients that had been treated in a child psychiatry unit and diagnosed with posttraumatic stress disorder and 83 healthy volunteers that were attending middle or high school during the study period. For reliability analyses, the internal consistency coefficient and the test-retest correlation coefficient were measured. For validity analyses, the exploratory factor analysis and correlation analysis with the Child Posttraumatic Stress Reaction Index for concurrent validity were measured. The Cronbach's alpha (the internal consistency coefficient) of the scale was 0.909, and the test-retest correlation coefficient was 0.663. One factor that could explain 58.5% of the variance was obtained and was congruent with the original construct of the scale. As for concurrent validity, the scale showed high correlation with the Child Posttraumatic Stress Reaction Index. It was concluded that the Turkish version of the DSM-5 Posttraumatic Stress Symptom Severity Scale-Child Form can be used as a valid and reliable tool.

  9. Validation of the Educational Stress Scale for Adolescents (ESSA) in Vietnam.

    Science.gov (United States)

    Truc, Thai Thanh; Loan, Kim Xuan; Nguyen, Nguyen Do; Dixon, Jason; Sun, Jiandong; Dunne, Michael Patrick

    2015-03-01

    To date, there has been little systematic, quantitative research on the links between academic pressure and mental health among adolescents in Asia, and none in Vietnam. In part, this is because of a lack of appropriate tools to measure this complex phenomenon. This study was to validate the Educational Stress Scale for Adolescents (ESSA), developed and tested in China, with the aim of fostering further research in Asia. A total of 1283 students were recruited in 3 secondary schools and 3 high schools in Ho Chi Minh City, Vietnam. Anonymous, self-report questionnaires included the ESSA and previously validated measures of mental health. Among the 1226 questionnaires available, 54% of respondents were female. The mean age was 15.3 years. Students reported substantial study burden. The ESSA had good internal consistency, and factorial validity and concurrent validity were established. The ESSA is a suitable measure for school-based mental health research in Asia. © 2012 APJPH.

  10. Physical modelling of granular flows at multiple-scales and stress levels

    Science.gov (United States)

    Take, Andy; Bowman, Elisabeth; Bryant, Sarah

    2015-04-01

    The rheology of dry granular flows is an area of significant focus within the granular physics, geoscience, and geotechnical engineering research communities. Studies performed to better understand granular flows in manufacturing, materials processing or bulk handling applications have typically focused on the behavior of steady, continuous flows. As a result, much of the research on relating the fundamental interaction of particles to the rheological or constitutive behaviour of granular flows has been performed under (usually) steady-state conditions and low stress levels. However, landslides, which are the primary focus of the geoscience and geotechnical engineering communities, are by nature unsteady flows defined by a finite source volume and at flow depths much larger than typically possible in laboratory experiments. The objective of this paper is to report initial findings of experimental studies currently being conducted using a new large-scale landslide flume (8 m long, 2 m wide slope inclined at 30° with a 35 m long horizontal base section) and at elevated particle self-weight in a 10 m diameter geotechnical centrifuge to investigate the granular flow behavior at multiple-scales and stress levels. The transparent sidewalls of the two flumes used in the experimental investigation permit the combination of observations of particle-scale interaction (using high-speed imaging through transparent vertical sidewalls at over 1000 frames per second) with observations of the distal reach of the landslide debris. These observations are used to investigate the applicability of rheological models developed for steady state flows (e.g. the dimensionless inertial number) in landslide applications and the robustness of depth-averaged approaches to modelling dry granular flow at multiple scales. These observations indicate that the dimensionless inertial number calculated for the flow may be of limited utility except perhaps to define a general state (e.g. liquid

  11. Cross-cultural validation of the Depression Anxiety Stress Scale-21 in China.

    Science.gov (United States)

    Wang, Kui; Shi, Hai-Song; Geng, Fu-Lei; Zou, Lai-Quan; Tan, Shu-Ping; Wang, Yi; Neumann, David L; Shum, David H K; Chan, Raymond C K

    2016-05-01

    The gap between the demand and delivery of mental health services in mainland China can be reduced by validating freely available and psychometrically sound psychological instruments. The present research examined the Chinese version of the 21-item Depression Anxiety Stress Scales (DASS-21). Study 1 administered the DASS-21 to 1,815 Chinese college students and found internal consistency indices (Cronbach's alpha) of .83, .80, and .82 for the Depression, Anxiety, and Stress subscales, respectively, and .92 for the total DASS total. Test-retest reliability over a 6-month interval was .39 to .46 for each of the 3 subscales and .46 for the total DASS. Moderate convergent validity of the Depression and Anxiety subscales was demonstrated via significant correlations with the Chinese Beck Depression Inventory (r = .51 at Time 1 and r = .64 at Time 2) and the Chinese State-Trait Anxiety Inventory (r = .41), respectively. Confirmatory factor analyses supported the original 3-factor model with 1 minor change (nonnormed fit index [NNFI] = .964, comparative fit index [CFI] = .968, and root mean square error of approximation [RMSEA] = .079). Study 2 examined the clinical utility of the Chinese DASS-21 in 166 patients with schizophrenia and 90 matched healthy controls. Patients had higher Depression and Anxiety but not Stress subscale scores than healthy controls. A discriminant function composed of the linear combination of 3 subscale scores correctly discriminated 69.92% of participants, which again supported the potential clinical utility of the DASS in mainland China. Taken together, findings in these studies support the cross-cultural validity of the DASS-21 in China. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  12. A Japanese version of the Perceived Stress Scale: cross-cultural translation and equivalence assessment

    Directory of Open Access Journals (Sweden)

    Mimura Chizu

    2008-09-01

    Full Text Available Abstract Background This paper describes the development of a Japanese version of the Perceived Stress Scale (PSS, and examines the equivalence between the original and translated version. The PSS is one of the few instruments to measure a global level of perceived stress, and has been widely used in a range of clinical and research settings. The PSS has already been translated into several languages, but there is no validated Japanese version. Methods A forward-backward procedure was implemented. Multiple forward and backward translations were produced, and a panel of reviewers verified conceptual and semantic equivalence between the source and final versions. Non-professional translators who were not brought up in bilingual families were used in order to enhance representativeness of language in the target populations. The PSS was administered to 222 native English speakers and the Japanese version (PSS-J to 1320 native Japanese speakers. Results Factor analysis showed similar factor loadings of the items and satisfactory factorial agreement between the PSS and PSS-J. Cronbach's alpha coefficient was high for both versions and for each factor. Conclusion It is concluded that the PSS and PSS-J are substantially equivalent and suited for use in comparative cross-cultural studies.

  13. Modelling sub-grid wetland in the ORCHIDEE global land surface model: evaluation against river discharges and remotely sensed data

    Directory of Open Access Journals (Sweden)

    B. Ringeval

    2012-07-01

    Full Text Available The quality of the global hydrological simulations performed by land surface models (LSMs strongly depends on processes that occur at unresolved spatial scales. Approaches such as TOPMODEL have been developed, which allow soil moisture redistribution within each grid-cell, based upon sub-grid scale topography. Moreover, the coupling between TOPMODEL and a LSM appears as a potential way to simulate wetland extent dynamic and its sensitivity to climate, a recently identified research problem for biogeochemical modelling, including methane emissions. Global evaluation of the coupling between TOPMODEL and an LSM is difficult, and prior attempts have been indirect, based on the evaluation of the simulated river flow. This study presents a new way to evaluate this coupling, within the ORCHIDEE LSM, using remote sensing data of inundated areas. Because of differences in nature between the satellite derived information – inundation extent – and the variable diagnosed by TOPMODEL/ORCHIDEE – area at maximum soil water content, the evaluation focuses on the spatial distribution of these two quantities as well as on their temporal variation. Despite some difficulties in exactly matching observed localized inundated events, we obtain a rather good agreement in the distribution of these two quantities at a global scale. Floodplains are not accounted for in the model, and this is a major limitation. The difficulty of reproducing the year-to-year variability of the observed inundated area (for instance, the decreasing trend by the end of 90s is also underlined. Classical indirect evaluation based on comparison between simulated and observed river flow is also performed and underlines difficulties to simulate river flow after coupling with TOPMODEL. The relationship between inundation and river flow at the basin scale in the model is analyzed, using both methods (evaluation against remote sensing data and river flow. Finally, we discuss the potential of

  14. Higher stress scores for female medical students measured by the Kessler Psychological Distress Scale (K10) in Pakistan

    OpenAIRE

    Khadija Qamar; Muhammad Rizwan Bash Kiani; Aisha Ayyub; Atif Ahmed Khan; Mohammad Osama

    2014-01-01

    The aim of this study was to determine the stress level of medical students and the relationship between stress and academic year. A cross-sectional, descriptive study was conducted at an undergraduate medical school with a five-year curriculum, in Pakistan, from January 2014 to April 2014. Medical students in the first four years were included in the study. The Kessler Psychological Distress Scale (K10), a self-administered questionnaire, was distributed to the students. A total of 445 medic...

  15. Growing Out of Stress: The Role of Cell- and Organ-Scale Growth Control in Plant Water-Stress Responses

    National Research Council Canada - National Science Library

    Feng, Wei; Lindner, Heike; Robbins, 2nd, Neil E; Dinneny, José R

    2016-01-01

    .... While much research has focused on exploring the molecular mechanisms underlying the cellular signaling events governing water-stress responses, it is also important to consider the role organismal...

  16. Stress

    Science.gov (United States)

    ... natural disaster. This type of stress can cause post-traumatic stress disorder (PTSD). Different people may feel stress in different ways. Some people experience digestive symptoms. Others may have headaches, sleeplessness, depressed mood, anger, ...

  17. Numerical Simulation of Atmospheric Boundary Layer Flow Over Battlefield-scale Complex Terrain: Surface Fluxes From Resolved and Subgrid Scales

    Science.gov (United States)

    2015-07-06

    Grimmond, 2015: Proc. 9th International Conference on Urban Climate , Paris, France. Anderson W, Li Q, Bou-Zeid E, 2014: Proc. of American...represen- tative information is known about the macroscale attributes of these coher- ent motions, we have developed a sim- ple, semi -empirical model to...dust from arid landscapes on the Llano Estacado in west Texas and eastern New Mexico. • Under Review: National Science Foundation, Fluid Dynamics Program

  18. A variational multi-scale method with spectral approximation of the sub-scales: Application to the 1D advection-diffusion equations

    KAUST Repository

    Chacón Rebollo, Tomás

    2015-03-01

    This paper introduces a variational multi-scale method where the sub-grid scales are computed by spectral approximations. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base of eigenfunctions which are orthonormal in weighted L2 spaces. This allows to element-wise calculate the sub-grid scales by means of the associated spectral expansion. We propose a feasible VMS-spectral method by truncation of this spectral expansion to a finite number of modes. We apply this general framework to the convection-diffusion equation, by analytically computing the family of eigenfunctions. We perform a convergence and error analysis. We also present some numerical tests that show the stability of the method for an odd number of spectral modes, and an improvement of accuracy in the large resolved scales, due to the adding of the sub-grid spectral scales.

  19. Organismal climatology: analyzing environmental variability at scales relevant to physiological stress.

    Science.gov (United States)

    Helmuth, Brian; Broitman, Bernardo R; Yamane, Lauren; Gilman, Sarah E; Mach, Katharine; Mislan, K A S; Denny, Mark W

    2010-03-15

    Predicting when, where and with what magnitude climate change is likely to affect the fitness, abundance and distribution of organisms and the functioning of ecosystems has emerged as a high priority for scientists and resource managers. However, even in cases where we have detailed knowledge of current species' range boundaries, we often do not understand what, if any, aspects of weather and climate act to set these limits. This shortcoming significantly curtails our capacity to predict potential future range shifts in response to climate change, especially since the factors that set range boundaries under those novel conditions may be different from those that set limits today. We quantitatively examine a nine-year time series of temperature records relevant to the body temperatures of intertidal mussels as measured using biomimetic sensors. Specifically, we explore how a 'climatology' of body temperatures, as opposed to long-term records of habitat-level parameters such as air and water temperatures, can be used to extrapolate meaningful spatial and temporal patterns of physiological stress. Using different metrics that correspond to various aspects of physiological stress (seasonal means, cumulative temperature and the return time of extremes) we show that these potential environmental stressors do not always occur in synchrony with one another. Our analysis also shows that patterns of animal temperature are not well correlated with simple, commonly used metrics such as air temperature. Detailed physiological studies can provide guidance to predicting the effects of global climate change on natural ecosystems but only if we concomitantly record, archive and model environmental signals at appropriate scales.

  20. Experimental scale model study of cracking in brick masonry under tensile and shear stress

    Directory of Open Access Journals (Sweden)

    Gálvez Ruiz, J. C.

    2008-09-01

    Full Text Available This article discusses the results of research conducted on the failure behaviour of brick masonry under tensile and shear stress. The study was designed to develop test models and generate experimental results able to provide greater insight into tensile and shear stresses cracking in brick masonry. The results of a campaign conducted with two types of specimens are discussed: 1 double-edge notched specimens under non-symmetrical compression stress, and 2 three point bending specimens under nonsymmetrical loading. Tests were run on specimens of similar size (similarity rate 2 and different bed joint orientation to determine how bed joint orientation affects crack propagation. The tests were conducted on scale models (1/4 of a single wythe, stretcher bond brickwork masonry wall one half foot thick.Este artículo presenta los resultados de la investigación realizada sobre el comportamiento en rotura de la fábrica de ladrillo bajo solicitaciones de tracción y cortante. La investigación está encaminada a proporcionar modelos de ensayo y resultados experimentales que permitan conocer mejor los procesos de agrietamiento de la fábrica de ladrillo bajo tensiones normales de tracción y tangenciales. Se presentan los resultados de una campaña experimental desarrollada con dos tipos de probeta: 1 la probeta compacta con doble entalla solicitada a compresión asimétrica, y 2 la probeta de flexión con entalla solicitada bajo carga asimétrica aplicada en tres puntos. Se han ensayado probetas de dos tamaños semejantes (razón de semejanza 2 y varias orientaciones de los tendeles, con el fin de ver cómo afecta la orientación de los tendeles en la propagación de las grietas. Los ensayos se han realizado con probetas a escala 1/4 de un muro de fábrica de ladrillo de una hoja a soga de medio pie de espesor.

  1. The Hassles Assessment Scale for Students in College: measuring the frequency and unpleasantness of and dwelling on stressful events.

    Science.gov (United States)

    Sarafino, E P; Ewing, M

    1999-09-01

    Development of the Hassles Assessment Scale for Students in College, a new scale to measure students' stress, is described. In the scale, students rate each of 54 hassles for its frequency and unpleasantness in the past month and indicate the degree to which they dwelt or ruminated on it. Very high levels of internal consistency for the frequency, unpleasantness, and dwelling measures were found. Correlational analyses demonstrated the scale's criterion validity (scores were negatively correlated with the number of hours respondents reported engaging in physical exercise) and congruent validity (scores were positively correlated with scores on the Inventory of College Students' Recent Life Experience, an established scale for assessing student hassles). Exploratory factor analyses suggested the possibility that many items on the scale are independent, with each contributing some specific variance to the total variance of the item pool that is not shared with other items.

  2. Multi-scale finite element modelling at the posterior lumbar vertebra: analysis of pedicle stresses due to pars fracture.

    Science.gov (United States)

    Inceoğlu, Serkan; Mageswaran, Prasath

    2014-05-01

    Multi-scale finite element (FE) model is a cost-effective way to analyse stress response of micro-level structures to the changes in loading at macro-level. This study deals with the development of a multi-scale model of a human vertebra and stress changes in the pedicle at high resolution after a gross fracture at the posterior neural arch. Spondylolysis (pars fracture) is a painful condition occurring in the vertebral neural arch and common especially among the athletic young population. The fracture of the pars significantly alters load distribution and load transfer characteristics at the neural arch. Structural changes in the posterior vertebra due to the new loading patterns can trigger secondary complications. Clinical reports have shown the association of pedicle hypertrophy or pedicle fracture with unilateral pars fractures. However, the biomechanical consequences of pars fracture and its effect on the pedicle have never been studied in detail. Therefore, we prepared a multi-scale model of posterior vertebra with continuum laminar complex model combined with micro-FE model of a pedicle section. The results showed that stress at the contralateral pars and pedicle increased after unilateral pars fracture simulation. High-stress regions were found around the outer boundaries of the pedicle. This model and information are helpful in understanding the stress changes in the pedicle and can be used for adaptive remodelling studies.

  3. The Short Version of the Depression Anxiety Stress Scales (DASS-21): Factor Structure in a Young Adolescent Sample

    Science.gov (United States)

    Szabo, Marianna

    2010-01-01

    This study explored the factor structure of the short form of the Depression Anxiety Stress Scales (DASS-21; Lovibond & Lovibond, 1995b) in a young adolescent sample. A group of 484 high school students ("Mean" age = 13.62 years, Min = 11.83, Max = 15.67 years, 52 % boys) completed the DASS-21. Several models were tested using Confirmatory Factor…

  4. Cross-cultural adaptation and validation of the Danish consensus version of the 10-item Perceived Stress Scale

    DEFF Research Database (Denmark)

    Eskildsen, Anita; Dalgaard, Vita Ligaya; Nielsen, Kent Jacob

    2015-01-01

    OBJECTIVES: The aims of the present study were to (i) cross-culturally adapt a Danish consensus version of the 10-item Perceived Stress Scale (PSS-10) and (ii) evaluate its psychometric properties in terms of agreement, reliability, validity, responsiveness, and interpretability among patients...

  5. The Border Community & Immigration Stress Scale: A Preliminary Examination of a Community Responsive Measure in Two Southwest Samples

    Science.gov (United States)

    Carvajal, Scott C.; Rosales, Cecilia; Rubio-Goldsmith, Raquel; Sabo, Samantha; Ingram, Maia; McClelland, Debra Jean; Redondo, Floribella; Torres, Emma; Romero, Andrea J.; Oleary, Anna Ochoa; Sanchez, Zoila; de Zapien, Jill Guernsey

    2015-01-01

    Background Understanding contemporary socio-cultural stressors may assist educational, clinical and policy-level health promotion efforts. This study presents descriptive findings on a new measure, the Border Community & Immigration Stress Scale (BCISS). Methods The data were from two community surveys as part of community based participatory projects conducted in the Southwestern US border region. This scale includes stressful experiences reflected in extant measures, with new items reflecting heightened local migration pressures and health care barriers. Results Stressors representing each main domain, including novel ones, were reported with frequency and at high intensity in the predominantly Mexican-descent samples. Total stress was also significantly associated with mental and physical health indicators. Discussion The study suggests particularly high health burdens tied to the experience of stressors in the US border region. Further, many of the stressors are also likely relevant for other communities within developed nations also experiencing high levels of migration. PMID:22430894

  6. The border community and immigration stress scale: a preliminary examination of a community responsive measure in two Southwest samples.

    Science.gov (United States)

    Carvajal, Scott C; Rosales, Cecilia; Rubio-Goldsmith, Raquel; Sabo, Samantha; Ingram, Maia; McClelland, Debra Jean; Redondo, Floribella; Torres, Emma; Romero, Andrea J; O'Leary, Anna Ochoa; Sanchez, Zoila; de Zapien, Jill Guernsey

    2013-04-01

    Understanding contemporary socio-cultural stressors may assist educational, clinical and policy-level health promotion efforts. This study presents descriptive findings on a new measure, the border community and immigration stress scale. The data were from two community surveys as part of community based participatory projects conducted in the Southwestern US border region. This scale includes stressful experiences reflected in extant measures, with new items reflecting heightened local migration pressures and health care barriers. Stressors representing each main domain, including novel ones, were reported with frequency and at high intensity in the predominantly Mexican-descent samples. Total stress was also significantly associated with mental and physical health indicators. The study suggests particularly high health burdens tied to the experience of stressors in the US border region. Further, many of the stressors are also likely relevant for other communities within developed nations also experiencing high levels of migration.

  7. The Bahasa Melayu version of the Nursing Stress Scale among nurses: a reliability study in Malaysia.

    Science.gov (United States)

    Rosnawati, Muhamad Robat; Moe, Htay; Masilamani, Retneswari; Darus, A

    2010-10-01

    The Nursing Stress Scale (NSS) has been shown to be a valid and reliable instrument to assess occupational stressors among nurses. The NSS, which was previously used in the English version, was translated and back-translated into Bahasa Melayu. This study was conducted to assess the reliability of the Bahasa Melayu version of the NSS among nurses for future studies in this country. The reliability of the NSS was assessed after its readministration to 30 nurses with a 2-week interval. The Spearman coefficient was calculated to assess its stability. The internal consistency was measured through 4 measures: Cronbach's α, Spearman-Brown, Guttman split-half, and standardized item α coefficients. The total response rate was 70%. Test-retest reliability showed remarkable stability (Spearman's ρ exceeded .70). All 4 measures of internal consistency among items indicated a satisfactory level (coefficients in the range of .68 to .87). In conclusion, the Bahasa Melayu version of the NSS is a reliable and useful instrument for measuring the possible stressors at the workplace among nurses.

  8. Cellular adaptation to biomechanical stress across length scales in tissue homeostasis and disease.

    Science.gov (United States)

    Gilbert, Penney M; Weaver, Valerie M

    2017-07-01

    Human tissues are remarkably adaptable and robust, harboring the collective ability to detect and respond to external stresses while maintaining tissue integrity. Following injury, many tissues have the capacity to repair the damage - and restore form and function - by deploying cellular and molecular mechanisms reminiscent of developmental programs. Indeed, it is increasingly clear that cancer and chronic conditions that develop with age arise as a result of cells and tissues re-implementing and deregulating a selection of developmental programs. Therefore, understanding the fundamental molecular mechanisms that drive cell and tissue responses is a necessity when designing therapies to treat human conditions. Extracellular matrix stiffness synergizes with chemical cues to drive single cell and collective cell behavior in culture and acts to establish and maintain tissue homeostasis in the body. This review will highlight recent advances that elucidate the impact of matrix mechanics on cell behavior and fate across these length scales during times of homeostasis and in disease states. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. The Malay Version of the Perceived Stress Scale (PSS)-10 is a Reliable and Valid Measure for Stress among Nurses in Malaysia.

    Science.gov (United States)

    Sandhu, Sukhvinder Singh; Ismail, Noor Hassim; Rampal, Krishna Gopal

    2015-11-01

    The Perceived Stress Scale-10 (PSS-10) is widely used to assess stress perception. The aim of this study was to translate the original PSS-10 into Malay and assess the reliability and validity of the Malay version among nurses. The Malay version of the PSS-10 was distributed among 229 nurses from four government hospitals in Selangor State. Test-retest reliability and concurrent validity was conducted with 25 nurses with the Malay version of the Depression Anxiety Stress Scales (DASS) 21. Cronbach's alpha, confirmatory factor analysis (CFA), intraclass correlation coefficient and Pearson's r correlation coefficient were used to determine the psychometric properties of the Malay PSS-10. Two factor components were yielded through exploratory factor analysis with eigenvalues of 3.37 and 2.10, respectively. Both of the factors accounted for 54.6% of the variance. CFA yielded a two-factor structure with satisfactory goodness-of-fit indices [x2/df = 2.43; comparative fit index (CFI) = 0.92, goodness-of-fit Index (GFI) = 0.94; standardised root mean square residual (SRMR) = 0.07 and root mean square error of approximation (RMSEA) = 0.08 (90% CI = 0.07-0.09)]. The Cronbach's alpha coefficient for the total items was 0.63 (0.82 for factor 1 and 0.72 for factor 2). The intraclass correlation coefficient (ICC) was 0.81 (95% CI: 0.62-0.91) for test-retest reliability testing after seven days. The total score and the negative component of the PSS-10 correlated significantly with the stress component of the DASS-21: (r = 0.61, P stress perception. Therefore, this questionnaire is valid in assessing stress perception among nurses in Malaysia.

  10. Development of short questionnaire to measure an extended set of role expectation conflict, coworker support and work-life balance: The new job stress scale

    National Research Council Canada - National Science Library

    Shukla, Abhishek; Srivastava, Rajeev

    2016-01-01

    This study aimed to investigate the reliability and validity of a new version of job stress scale, which measures the extended set of psychosocial stressors by adding new scales to the current version...

  11. Evaluation of residual stresses in laser clad coating at the micrometer scale

    NARCIS (Netherlands)

    Furár, I.; Ocelík, V.; De Hosson, J.T.M.

    2011-01-01

    Residual stresses may have beneficial or detrimental effects to the materials properties and therefore precise knowledge and control of residual stresses are of high practical relevance. For the stress-relaxation measurement at a micro level we explored the slit milling (crack compliance) method

  12. The Development, Evaluation, and Validation of a Financial Stress Scale for Undergraduate Students

    Science.gov (United States)

    Northern, Jebediah J.; O'Brien, William H.; Goetz, Paul W.

    2010-01-01

    Financial stress is commonly experienced among college students and is associated with adverse academic, mental health, and physical health outcomes. Surprisingly, no validated measures of financial stress have been developed for undergraduate populations. The present study was conducted to generate and evaluate a measure of financial stress for…

  13. Variation in community structure across vertical intertidal stress gradients: how does it compare with horizontal variation at different scales?

    Directory of Open Access Journals (Sweden)

    Nelson Valdivia

    Full Text Available In rocky intertidal habitats, the pronounced increase in environmental stress from low to high elevations greatly affects community structure, that is, the combined measure of species identity and their relative abundance. Recent studies have shown that ecological variation also occurs along the coastline at a variety of spatial scales. Little is known, however, on how vertical variation compares with horizontal variation measured at increasing spatial scales (in terms of sampling interval. Because broad-scale processes can generate geographical patterns in community structure, we tested the hypothesis that vertical ecological variation is higher than fine-scale horizontal variation but lower than broad-scale horizontal variation. To test this prediction, we compared the variation in community structure across intertidal elevations on rocky shores of Helgoland Island with independent estimates of horizontal variation measured at the scale of patches (quadrats separated by 10s of cm, sites (quadrats separated by a few m, and shores (quadrats separated by 100s to 1000s of m. The multivariate analyses done on community structure supported our prediction. Specifically, vertical variation was significantly higher than patch- and site-scale horizontal variation but lower than shore-scale horizontal variation. Similar patterns were found for the variation in abundance of foundation taxa such as Fucus spp. and Mastocarpus stellatus, suggesting that the effects of these canopy-forming algae, known to function as ecosystem engineers, may explain part of the observed variability in community structure. Our findings suggest that broad-scale processes affecting species performance increase ecological variability relative to the pervasive fine-scale patchiness already described for marine coasts and the well known variation caused by vertical stress gradients. Our results also indicate that experimental research aiming to understand community structure on

  14. Growing Out of Stress: The Role of Cell- and Organ-Scale Growth Control in Plant Water-Stress Responses[OPEN

    Science.gov (United States)

    Robbins, Neil E.

    2016-01-01

    Water is the most limiting resource on land for plant growth, and its uptake by plants is affected by many abiotic stresses, such as salinity, cold, heat, and drought. While much research has focused on exploring the molecular mechanisms underlying the cellular signaling events governing water-stress responses, it is also important to consider the role organismal structure plays as a context for such responses. The regulation of growth in plants occurs at two spatial scales: the cell and the organ. In this review, we focus on how the regulation of growth at these different spatial scales enables plants to acclimate to water-deficit stress. The cell wall is discussed with respect to how the physical properties of this structure affect water loss and how regulatory mechanisms that affect wall extensibility maintain growth under water deficit. At a higher spatial scale, the architecture of the root system represents a highly dynamic physical network that facilitates access of the plant to a heterogeneous distribution of water in soil. We discuss the role differential growth plays in shaping the structure of this system and the physiological implications of such changes. PMID:27503468

  15. Improving Objective Measurement in Nursing Research: Rasch Model Analysis and Diagnostics of the Nursing Students' Clinical Stress Scale.

    Science.gov (United States)

    Bourke, Mary; Wallace, Linda; Greskamp, Marlene; Tormoehlen, Lucy

    2015-01-01

    The purpose of this study is to use Rasch model diagnostics and analysis to understand survey item (questions) functioning of the Nursing Students' Clinical Stress Scale, a rating scale instrument developed by Whang (2002). A rating scale instrument originally written in Korean was translated into English and administered to a convenience sample of all junior (46) and senior (64) students at a large Midwest university. Rasch model analysis provided the empirical evidence to support that the survey items measured the latent variable, stress. Diagnostic results indicated the need for improved category labeling. It is imperative that nursing educators evaluate and facilitate inter- and intraprofessional relationships between students and staff/faculty as well as understand the student experience.

  16. Posttraumatic stress disorder in veterans: the utility of the MMPI-2-RF validity scales in detecting overreported symptoms.

    Science.gov (United States)

    Goodwin, Brandee E; Sellbom, Martin; Arbisi, Paul A

    2013-09-01

    The current investigation examined the utility of the overreporting validity scales of the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF; Ben-Porath & Tellegen, 2008) in detecting noncredible reporting of symptoms of posttraumatic stress disorder (PTSD) in a sample of disability-seeking veterans. We also examined the effect of mental health knowledge on the utility of these scales by investigating the extent to which these scales differentiate between veterans with PTSD and individuals with mental health training who were asked to feign symptoms of PTSD on the test. Group differences on validity scale scores indicated that these scales were associated with large effect sizes for differentiating veterans who overreported from those with PTSD and for differentiating between mental health professionals and veterans with PTSD. Implications of these results in terms of clinical practice are discussed.

  17. Psychometric properties of the Perceived Stress Scale in a sample of German dementia patients and their caregivers.

    Science.gov (United States)

    Deeken, Friederike; Häusler, Andreas; Nordheim, Johanna; Rapp, Michael; Knoll, Nina; Rieckmann, Nina

    2017-07-24

    The aim of the present study was to investigate the psychometric characteristics of the Perceived Stress Scale (PSS) in a sample of dementia patients and their spousal caregivers. We investigated the reliability and validity of the 14-item PSS in a sample of 80 couples, each including one spouse who had been diagnosed with mild to moderate dementia (mean age 75.55, SD = 5.85, 38.7% female) and one spousal caregiver (mean age 73.06, SD = 6.75, 61.3% female). We also examined the factor structure and sensitivity of the scale with regard to gender differences. Exploratory factor analysis of the PSS revealed a two-factor solution for the scale; the first factor reflected general stress while the second factor consisted of items reflecting the perceived ability to cope with stressors. A confirmatory factor analysis verified that the data were a better fit for the two-factor model than a one-factor model. The two factors of the PSS showed good reliability for patients as well as for caregivers ranging between α = 0.73 and α = 0.82. Perceived stress was significantly positively correlated with depressive symptomatology in both caregivers and patients. Mean PSS scores did not significantly differ between male and female patients nor did they differ between male and female caregivers. The present data indicate that the PSS provides a reliable and valid measure of perceived stress in dementia patients and their caregivers.

  18. Morphology Dependent Flow Stress in Nickel-Based Superalloys in the Multi-Scale Crystal Plasticity Framework

    Directory of Open Access Journals (Sweden)

    Shahriyar Keshavarz

    2017-11-01

    Full Text Available This paper develops a framework to obtain the flow stress of nickel-based superalloys as a function of γ-γ’ morphology. The yield strength is a major factor in the design of these alloys. This work provides additional effects of γ’ morphology in the design scope that has been adopted for the model developed by authors. In general, the two-phase γ-γ’ morphology in nickel-based superalloys can be divided into three variables including γ’ shape, γ’ volume fraction and γ’ size in the sub-grain microstructure. In order to obtain the flow stress, non-Schmid crystal plasticity constitutive models at two length scales are employed and bridged through a homogenized multi-scale framework. The multi-scale framework includes two sub-grain and homogenized grain scales. For the sub-grain scale, a size-dependent, dislocation-density-based finite element model (FEM of the representative volume element (RVE with explicit depiction of the γ-γ’ morphology is developed as a building block for the homogenization. For the next scale, an activation-energy-based crystal plasticity model is developed for the homogenized single crystal of Ni-based superalloys. The constitutive models address the thermo-mechanical behavior of nickel-based superalloys for a large temperature range and include orientation dependencies and tension-compression asymmetry. This homogenized model is used to obtain the morphology dependence on the flow stress in nickel-based superalloys and can significantly expedite crystal plasticity FE simulations in polycrystalline microstructures, as well as higher scale FE models in order to cast and design superalloys.

  19. Assessment of the Depression, Anxiety, and Stress Scale (DASS-21) in untreated obstructive sleep apnea (OSA).

    Science.gov (United States)

    Nanthakumar, Shenooka; Bucks, Romola S; Skinner, Timothy C; Starkstein, Sergio; Hillman, David; James, Alan; Hunter, Michael

    2017-10-01

    The assessment of depression in obstructive sleep apnea (OSA) is confounded by symptom overlap. The Depression, Anxiety, and Stress Scale-short form (DASS-21) is a commonly used measure of negative affect, but it not known whether the DASS-21 is suitable for use in an OSA sample. This study compared the fit of Lovibond and Lovibond's (1995) correlated 3-factor structure of the DASS-21 and measurement invariance between a non-OSA and an OSA sample using confirmatory factor analysis. As measurement invariance was not found, to determine the source of non-invariance differential item functioning (DIF) was examined using dMACS. The correlated 3-factor structure (with correlated errors) of the DASS-21 was a better fit in the non-OSA sample. dMACS indicated that there was a degree of DIF for each of the subscales, especially for the Anxiety subscale, in which 2 symptoms (that are also physiological symptoms of OSA) produced lower severity scores in the OSA sample compared with the non-OSA sample. However, the degree of DIF for each of the subscales is not sufficient to cause concern when using the DASS-21; therefore, the total DASS-21 is suitable for use in an OSA sample. Interestingly, the impact of symptom overlap in anxiety symptoms may be reducing anxiety scores because of DIF, which contrasts with the proposed effect of symptom overlap in depression, where it leads to the inflation of depression scores in OSA. This deserves greater consideration in relation to OSA and other clinical disorders or chronic illness conditions with different patterns of overlapping symptoms. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  20. Time line cell tracking for the approximation of lagrangian coherent structures with subgrid accuracy

    KAUST Repository

    Kuhn, Alexander

    2013-12-05

    Lagrangian coherent structures (LCSs) have become a widespread and powerful method to describe dynamic motion patterns in time-dependent flow fields. The standard way to extract LCS is to compute height ridges in the finite-time Lyapunov exponent field. In this work, we present an alternative method to approximate Lagrangian features for 2D unsteady flow fields that achieve subgrid accuracy without additional particle sampling. We obtain this by a geometric reconstruction of the flow map using additional material constraints for the available samples. In comparison to the standard method, this allows for a more accurate global approximation of LCS on sparse grids and for long integration intervals. The proposed algorithm works directly on a set of given particle trajectories and without additional flow map derivatives. We demonstrate its application for a set of computational fluid dynamic examples, as well as trajectories acquired by Lagrangian methods, and discuss its benefits and limitations. © 2013 The Authors Computer Graphics Forum © 2013 The Eurographics Association and John Wiley & Sons Ltd.

  1. Systemic Stress: The Army Lifestyle through the Social Readjustment Scale Lens

    Science.gov (United States)

    2013-05-22

    to include migraines, chest pains , muscle pains , and general, non- specified pains . It can lead to muscle tension and hypertension. Stress can cause...academic stress and season on 24 hour mean concentrations of ACTH, cortisol, and beta- endorphin . Psychoneuroendocrinology 20, no. 5: 499-508. Mayo

  2. Are happier people less vulnerable to rumination, anxiety, and post-traumatic stress? Evidence from a large scale disaster

    Directory of Open Access Journals (Sweden)

    Cristian Zanon

    2016-01-01

    Full Text Available Abstract The present longitudinal study tested hypotheses about the relationship of subjective well-being and neuroticism with rumination, anxiety, and post-traumatic stress in university students after a large scale disaster. Measures of subjective well-being and personality were obtained two months before the 2013 Santa Maria’s fire. Measures of rumination, PTSD and anxiety were collected five months after the disaster with the same students. The results provide evidence that life satisfaction correlated negatively with rumination, anxiety, and post-traumatic stress. Positive affect presented similar but slightly smaller negative correlations with these variables, while negative affect presented higher correlations with rumination, anxiety, and post-traumatic stress. These findings provide evidence that subjective well-being components may constitute important predictors of psychopathological symptomatology after a disaster and may be helpful to plan clinical interventions.

  3. Development and Validation of a Brief Measure of Psychological Resilience: An Adaptation of the Response to Stressful Experiences Scale.

    Science.gov (United States)

    De La Rosa, Gabriel M; Webb-Murphy, Jennifer A; Johnston, Scott L

    2016-03-01

    Resilience helps determine how people respond to stress. The Response to Stressful Events Scale (RSES) is an existing 22-item measure of resilience. We investigate the psychometric properties of the RSES and develop a 4-item measure of resilience using the most discriminating items from the RSES. Among two samples of military personnel presenting to mental health clinics, we see that the abbreviated resilience measure displays comparable internal consistency and test-retest reliability (versus the existing RSES). Among a sample of deployed military personnel, the abbreviated scale relates to validated measures of psychological strain. The 4-item abbreviated RSES measure is a brief, reliable, and valid measure of resilience. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

  4. Use of fundamental condensation heat transfer experiments for the development of a sub-grid liquid jet condensation model

    Energy Technology Data Exchange (ETDEWEB)

    Buschman, Francis X., E-mail: Francis.Buschman@unnpp.gov; Aumiller, David L.

    2017-02-15

    Highlights: • Direct contact condensation data on liquid jets up to 1.7 MPa in pure steam and in the presence of noncondensable gas. • Identified a pressure effect on the impact of noncondensables to suppress condensation heat transfer not captured in existing data or correlations. • Pure steam data is used to develop a new correlation for condensation heat transfer on subcooled liquid jets. • Noncondensable data used to develop a modification to the renewal time estimate used in the Young and Bajorek correlation for condensation suppression in the presence of noncondensables. • A jet injection boundary condition, using a sub-grid jet condensation model, is developed for COBRA-IE which provides a more detailed estimate of the condensation rate on the liquid jet and allows the use of jet specific closure relationships. - Abstract: Condensation on liquid jets is an important phenomenon for many different facets of nuclear power plant transients and analyses such as containment spray cooling. An experimental facility constructed at the Pennsylvania State University, the High Pressure Liquid Jet Condensation Heat Transfer facility (HPLJCHT), has been used to perform steady-state condensation heat transfer experiments in which the temperature of the liquid jet is measured at different axial locations allowing the condensation rate to be determined over the jet length. Test data have been obtained in a pure steam environment and with varying concentrations of noncondensable gas. This data extends the available jet condensation data from near atmospheric pressure up to a pressure of 1.7 MPa. An empirical correlation for the liquid side condensation heat transfer coefficient has been developed based on the data obtained in pure steam. The data obtained with noncondensable gas were used to develop a correlation for the renewal time as used in the condensation suppression model developed by Young and Bajorek. This paper describes a new sub-grid liquid jet

  5. The structure of stress: confirmatory factor analysis of a Chinese version of the stressors in Nursing Students Scale (SINS).

    Science.gov (United States)

    Watson, Roger; Yanhua, Chen; Ip, Maggie Y K; Smith, Graeme D; Wong, Thomas K S; Deary, Ian J

    2013-02-01

    Stress is a feature of the life of nursing students and this had been well studied. However, there are very few instruments to measure stress in nursing students specifically. One such instrument, the Stressors in Nursing Students Scale has been developed in Scotland and applied in studies in Hong Kong and Australia and proved useful alongside other measures of individual differences and psychological distress. To translate the Stressors in Nursing Students Scale into Chinese, test it with Chinese nursing students and explore the psychometric structure of stress in this population. Cross-sectional survey using a self-administered questionnaire. A large teaching hospital in Southwest Mainland China. Nursing students (n=1090) participated (1000 in the classroom and 90 on clinical placement); 862 from the classroom and 79 from clinical placements returned questionnaires (n=914) representing a return rate of 86.3%. Principal component analysis and confirmatory factor analysis using structural equation modelling. A four-factor structure was obtained from principal component analysis. This was confirmed (fit indices>0.9 and RMSEAstress-related factors were: Clinical (0.83), Finance (0.81), Confidence (0.82), and Education (0.70). The original structure of the SINS in English was confirmed in this large sample of Chinese nursing students. This will allow cross-cultural studies of stress in nursing students. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Climate-related environmental stress in intertidal grazers: scaling-up biochemical responses to assemblage-level processes

    Directory of Open Access Journals (Sweden)

    Elena Maggi

    2016-10-01

    Full Text Available Background Organisms are facing increasing levels of environmental stress under climate change that may severely affect the functioning of biological systems at different levels of organization. Growing evidence suggests that reduction in body size is a universal response of organisms to global warming. However, a clear understanding of whether extreme climate events will impose selection directly on phenotypic plastic responses and how these responses affect ecological interactions has remained elusive. Methods We experimentally investigated the effects of extreme desiccation events on antioxidant defense mechanisms of a rocky intertidal gastropod (Patella ulyssiponensis, and evaluated how these effects scaled-up at the population and assemblage levels. Results With increasing levels of desiccation stress, limpets showed significant lower levels of total glutathione, tended to grow less and had reduced per capita interaction strength on their resources. Discussion Results suggested that phenotypic plasticity (i.e., reduction in adults’ body size allowed buffering biochemical responses to stress to scale-up at the assemblage level. Unveiling the linkages among different levels of biological organization is key to develop indicators that can anticipate large-scale ecological impacts of climate change.

  7. Climate-related environmental stress in intertidal grazers: scaling-up biochemical responses to assemblage-level processes.

    Science.gov (United States)

    Maggi, Elena; Cappiello, Mario; Del Corso, Antonella; Lenzarini, Francesca; Peroni, Eleonora; Benedetti-Cecchi, Lisandro

    2016-01-01

    Organisms are facing increasing levels of environmental stress under climate change that may severely affect the functioning of biological systems at different levels of organization. Growing evidence suggests that reduction in body size is a universal response of organisms to global warming. However, a clear understanding of whether extreme climate events will impose selection directly on phenotypic plastic responses and how these responses affect ecological interactions has remained elusive. We experimentally investigated the effects of extreme desiccation events on antioxidant defense mechanisms of a rocky intertidal gastropod (Patella ulyssiponensis), and evaluated how these effects scaled-up at the population and assemblage levels. With increasing levels of desiccation stress, limpets showed significant lower levels of total glutathione, tended to grow less and had reduced per capita interaction strength on their resources. Results suggested that phenotypic plasticity (i.e., reduction in adults' body size) allowed buffering biochemical responses to stress to scale-up at the assemblage level. Unveiling the linkages among different levels of biological organization is key to develop indicators that can anticipate large-scale ecological impacts of climate change.

  8. Sub-grid combustion modeling for compressible two-phase reacting flows

    Science.gov (United States)

    Sankaran, Vaidyanathan

    2003-06-01

    A generic formulation for modeling the turbulent combustion in compressible, high Reynolds number, two-phase; reacting flows has been developed and validated. A sub-grid mixing/combustion model called Linear Eddy Mixing (LEM) model has been extended to compressible flows and used inside the framework of Large Eddy Simulation (LES) in this LES-LEM approach. The LES-LEM approach is based on the proposition that the basic mechanistic distinction between the convective and the molecular effects should be preserved for accurate prediction of complex flow-fields such as those encountered in many combustion systems. Liquid droplets (represented by computational parcels) are tracked using the Lagrangian approach wherein the Newton's equation of motion for the discrete particles are integrated explicitly in the Eulerian gas field. The gas phase LES velocity fields are used to estimate the instantaneous gas velocity at the droplet location. Drag effects due to the droplets on the gas phase and the heat transfer between the gas and the liquid phase are explicitly included. Thus, full coupling is achieved between the two phases in the simulation. Validation of the compressible LES-LEM approach is conducted by simulating the flow-field in an operational General Electric Aircraft Engines combustor (LM6000). The results predicted using the proposed approach compares well with the experiments and a conventional (G-equation) thin-flame model. Particle tracking algorithms used in the present study are validated by simulating droplet laden temporal mixing layers. Quantitative and qualitative comparison with the results of spectral DNS exhibits good agreement. Simulations using the current LES-LEM for freely propagating partially premixed flame in a droplet-laden isotropic turbulent field correctly captures the flame structure in the partially premixed flames. Due to the strong spatial variation of equivalence ratio a broad flame similar to a premixed flame is realized. The current

  9. Macro-scale topology optimization for controlling internal shear stress in a porous scaffold bioreactor.

    Science.gov (United States)

    Youssef, K; Mack, J J; Iruela-Arispe, M L; Bouchard, L-S

    2012-07-01

    Shear stress is an important physical factor that regulates proliferation, migration, and morphogenesis. In particular, the homeostasis of blood vessels is dependent on shear stress. To mimic this process ex vivo, efforts have been made to seed scaffolds with vascular and other cell types in the presence of growth factors and under pulsatile flow conditions. However, the resulting bioreactors lack information on shear stress and flow distributions within the scaffold. Consequently, it is difficult to interpret the effects of shear stress on cell function. Such knowledge would enable researchers to improve upon cell culture protocols. Recent work has focused on optimizing the microstructural parameters of the scaffold to fine tune the shear stress. In this study, we have adopted a different approach whereby flows are redirected throughout the bioreactor along channels patterned in the porous scaffold to yield shear stress distributions that are optimized for uniformity centered on a target value. A topology optimization algorithm coupled to computational fluid dynamics simulations was devised to this end. The channel topology in the porous scaffold was varied using a combination of genetic algorithm and fuzzy logic. The method is validated by experiments using magnetic resonance imaging readouts of the flow field. Copyright © 2012 Wiley Periodicals, Inc.

  10. Workplace stress in nursing workers from an emergency hospital: Job Stress Scale analysis Estrés en el trabajo de enfermería en hospital de emergencia: análisis usando la Job Stress Scale Estresse no trabalho da enfermagem em hospital de pronto-socorro: análise usando a Job Stress Scale

    Directory of Open Access Journals (Sweden)

    Janete de Souza Urbanetto

    2011-10-01

    Full Text Available This study identifies workplace stress according to the Job Stress Scale and associates it with socio-demographic and occupational variables of nursing workers from an emergency hospital. This is a cross-sectional study and data were collected through a questionnaire applied to 388 nursing professionals. Descriptive statistics were applied; univariate and multivariate analyses were performed. The results indicate there is a significant association with being a nursing technician or auxiliary, working in the position for more than 15 years, and having low social support, with 3.84, 2.25 and 4.79 times more chances of being placed in the ‘high strain job' quadrant. The study reveals that aspects related to the workplace should be monitored by competent agencies in order to improve the quality of life of nursing workers.Estudio que tuvo el objetivo identificar el estrés en el trabajo, según la Job Stress Scale y asociarlo con aspectos sociodemográficos y laborales de trabajadores de enfermería de un hospital de emergencia. Estudio de tipo transversal, cuyos datos fueron recolectados, por medio de cuestionario, con 388 profesionales de enfermería. El análisis fue realizado con la estadística descriptiva, análisis univariado y multivariado. Los resultados identificaron asociación significativa con el cargo de técnico/auxiliar de enfermería, tiempo en el cargo superior a 15 años y bajo apoyo social, con chances respectivas de 3,84; 2,25 y 4,79 mayores para el cuadrante alto desgaste. El estudio demostró que los aspectos relacionados al ambiente de trabajo deben ser acompañados por los órganos competentes con la finalidad de invertir recursos en la calidad de vida en el trabajo de la enfermería.Trata-se de estudo cujo objetivo foi identificar o estresse no trabalho, segundo a Job Stress Scale, e associá-lo aos aspectos sociodemográficos e laborais de trabalhadores de enfermagem de um hospital de pronto-socorro. É estudo tipo

  11. Influence of chemistry and climate on large induced large scale stresses in anisotropically fractured carbonates.

    Science.gov (United States)

    Toussaint, R.; Cornet, F.

    2012-04-01

    We will explore a simple model coupling for carbonate rocks the fracture density and orientation, the water chemistry and transport, the dissolution reactions and the expected irreversible rock deformation. Adding elasticity and boundary conditions, plus an estimation of the water source composition in the formation, we will estimate orders of magnitudes of the stress changes that can be expected from these processes in sedimentary basins over long times. We will in particular examine whether such intrinsic deformation mechanism can give a hint to explain the observed anisotropic stresses, in orientation and magnitude, in zones above the C.O.X. argillite formation in the Paris Basin, where the horizontal stress anisotropy has been shown to be important, whereas stress decoupling from the deep crustal roots should be effective, and no strong anisotropy would be expected in the absence of active deformation mechanism. In the Paris basin, the analysis of log cores shows that fractures and joints, up to meter-long ones, are common anisotropic features present in the carbonate rocks. Dissolution of calcite along these oriented features removes material with an a priori oriented flux reflecting this structural anisotropy, resulting in a non-isotropic deformation associated to this dissolution. We will present a simple model where dissolution and transport of dissolved calcite is associated with the deformation of the carbonate rock. Estimating the reaction constants, the chemical composition variation of the meteoric water, the rock permeability and the fracture density from observations around the Bure underground laboratory, we will estimate the order of magnitude of the deformations expected from these types of mechanisms. Such estimates have already been performed for dissolution along stylolites, e.g. by Clark, 1966; Renard et al., 2004; Schmittbuhl et al., 2004; Koehn et al., 2007. We will adapt these to reflect the anisotropic feature of the fractures present in

  12. The Vietnamese version of the Perceived Stress Scale (PSS-10): Translation equivalence and psychometric properties among older women.

    Science.gov (United States)

    Dao-Tran, Tiet-Hanh; Anderson, Debra; Seib, Charrlotte

    2017-02-06

    The Perceived Stress Scale 10 item (PSS-10) has been translated into more than 20 languages and used widely in different populations. Yet, to date, no study has tested psychometric properties of the instrument among older women and there is no Vietnamese version of the instrument. This study translated the PSS-10 into Vietnamese and assessed Vietnamese version of the Perceived Stress Scale 10 items (V-PSS-10) for translation equivalence, face validity, construct validity, correlations, internal consistency reliability, and test-retest reliability among 473 women aged 60 and over. The study found that V-PSS-10 retained the original meaning and was understood by Vietnamese older women. An exploratory factor analysis of the V-PSS-10 yielded a two-factor structure, and these two factors were significantly correlated (0.56, p perceived stress in future research and practice. However, future research would be useful to further endorse the validity and reliability of the V-PSS-10.

  13. Measuring Social Capital Investment: Scale Development and Examination of Links to Social Capital and Perceived Stress

    Science.gov (United States)

    Wegner, Rhiana; Gong, Jie; Fang, Xiaoyi; Kaljee, Linda

    2014-01-01

    Individuals with greater social capital have better health outcomes. Investment in social capital likely increases one’s own social capital, bearing great implications for disease prevention and health promotion. In this study, the authors developed and validated the Social Capital Investment Inventory (SCII). Direct effects of social capital investment on perceived stress, and indirect effects through social capital were examined. 397 Participants from Beijing and Wuhan, China completed surveys. Analyses demonstrated that the SCII has a single factor structure and strong internal consistency. Structural equation modeling showed that individuals who invested more in social capital had greater bonding social capital, and subsequently less perceived stress. Results suggest that disease prevention and health promotion programs should consider approaches to encourage social capital investment; individuals may be able to reduce stress by increasing their investment in social capital. Future research is needed to provide additional empirical support for the SCII and observed structural relationships. PMID:25648725

  14. Stress

    DEFF Research Database (Denmark)

    Keller, Hanne Dauer

    2015-01-01

    Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb.......Kapitlet handler om stress som følelse, og det trækker primært på de få kvalitative undersøgelser, der er lavet af stressforløb....

  15. Variational Multi-Scale method with spectral approximation of the sub-scales.

    KAUST Repository

    Dia, Ben Mansour

    2015-01-07

    A variational multi-scale method where the sub-grid scales are computed by spectral approximations is presented. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base of eigenfunctions which are orthonormal in weighted L2 spaces. We propose a feasible VMS-spectral method by truncation of this spectral expansion to a nite number of modes.

  16. In-silico analysis of water and carbon relations under stress conditions. A multi-scale perspective centered on fruit

    Directory of Open Access Journals (Sweden)

    Valentina eBALDAZZI

    2013-12-01

    Full Text Available Fruit development, from its early stages, is the result of a complex network of interacting processes, at different scales. These include cell division, cell expansion but also nutrient transports from the plant and exchanges with the environment. In the presence of nutrients limitation, in particular, the plant reacts as whole, by modifying its architecture, metabolism and reproductive strategy, determining the resources available for fruits development, which in turn affects the overall source-sink balance of the system.Here we present an integrated model of tomato that explicitly accounts for early developmental changes (from cell division to harvest, and use it to investigate the impact of water deficit and carbon limitation on nutrient fluxes and fruit growth, in both dry and fresh mass. Variability in fruit response is analyzed at two different scales: among trusses, at the plant level and within the cells population, at the fruit scale. Results show that the effect of stress on individual cells strongly depends on their age, size and uptake capabilities and that the timing of stress application, together with the fruit position on the plant, is crucial to determine the final phenotypic outcome. Water deficit and carbon depletion impacted either source size, source activity or sink strength with contrasted effects on fruit growth. An important prediction of the model is the major role of symplasmic transport of carbon in early stage of fruit development, as a catalyst of cells and fruit growth.

  17. Resilience in Men and Women Experiencing Sexual Assault or Traumatic Stress: Validation and Replication of the Scale of Protective Factors.

    Science.gov (United States)

    Ponce-Garcia, Elisabeth; Madewell, Amy N; Brown, Marina E

    2016-12-01

    The literature on sexual assault (SA) typically has been generalized to women and children. However, both men and women experience SA. Research shows that not all individuals experience the negative impacts of SA in the same way. The ability to buffer the negative effects of SA may lie in specific protective factors that determine resilience. Resilience scales used in adult populations have not been validated for use in SA samples. The purpose of the present study was to replicate the factor structure of a resilience scale, the Scale of Protective Factors (SPF), in a sample of emerging adults (n = 571) and to validate the replicated model on a subsample of the participants who reported SA (n = 173). Additionally, we sought to examine gender differences in mental health outcomes including depression and anxiety, and the availability of protective factors that determine resilience among those participants who reported experiencing SA (n = 173) as compared to other forms of traumatic stress (n = 132). The SPF achieved good model fit in the larger emerging adult sample and adequate model fit was achieved in the SA subsample. Results indicated significant gender differences in mental health outcomes with η2 ranging between .03 and .21. Implications and future directions are discussed. Copyright © 2016 International Society for Traumatic Stress Studies.

  18. Using the Brief Resilience Scale to Assess Chinese People’s Ability to Bounce Back From Stress

    Directory of Open Access Journals (Sweden)

    Julian C. L. Lai

    2014-10-01

    Full Text Available This study examined the utility of an adapted version of the Brief Resilience Scale (BRS to measure Chinese undergraduates’ ability to bounce back from stress. The BRS together with measures tapping optimism, self-esteem, pessimism, and physical health were administered to 547 Hong Kong and 268 mainland Chinese undergraduates. The BRS was found to measure one single construct and exhibited convergent validity in both samples. Further analyses using a path analytic model showed that the BRS scores substantially mediated the link between the two positive traits (optimism and self-esteem and physical health in the two samples. The results suggested that the BRS is a reliable and valid instrument for measuring Chinese undergraduates’ ability to bounce back from stress. The implications for further research related to resilience in Chinese people are discussed.

  19. Sensitivity of the scale partition for variational multiscale large-eddy simulation of channel flow

    NARCIS (Netherlands)

    Holmen, J.; Hughes, T.J.R.; Oberai, A.A.; Wells, G.N.

    2004-01-01

    The variational multiscale method has been shown to perform well for large-eddy simulation (LES) of turbulent flows. The method relies upon a partition of the resolved velocity field into large- and small-scale components. The subgrid model then acts only on the small scales of motion, unlike

  20. Relationships between occupational functioning and stress among radio journalists--Assessment by means of the Psychosocial Risk Scale.

    Science.gov (United States)

    Najder, Anna; Merecz-Kot, Dorota; Wójcik, Aleksandra

    2016-01-01

    Job characteristics and the consequences of everyday stress among radio journalists who are not exposed to traumatic events have not been studied sufficiently before. We aimed at determining the most common job characteristics and their stressfulness; relationships between stress exposure, health and occupational functioning; differences between radio journalists and other journalists, and also the psychosocial risk for health and functioning in this group. The studied group involved 208 journalists, 134 of whom worked in radio stations. The respondents filled in the Psychosocial Risks Scale (PRS) developed by the Department of Health and Work Psychology of the Nofer Institute of Occupational Medicine, Łódź, Poland. Requirement of mental effort and readiness to response quickly for most of the time as well as limited possibilities for promotion were the most frequent journalists' complaints. We confirmed that higher levels of stress resulted in worse functioning--the radio journalists who experienced lower stress assessed their health status and ability to work better, were more satisfied with particular aspects of their work, and were more involved in their work. They also presented a significantly lower turnover intention. Moreover, the radio journalists were more involved in their work than other journalists, but experienced lower satisfaction, took more sick leaves and had more days of absence. Well-known relationships between stress level, satisfaction and occupational functioning were confirmed. The most important conclusion refers to the fact that psychosocial risks and stress analysis should be based on the understanding of specificity of each occupation or even position. It is so, because the same job characteristic may pose a challenge for one person, while for another--it can result in extreme discomfort and anxiety--such an attitude broadens understanding of the phenomenon. We also confirmed that the PRS is a well-designed method, appropriate to

  1. Study of stress-strain and volume change behavior of emplaced municipal solid waste using large-scale triaxial testing.

    Science.gov (United States)

    Ramaiah, B J; Ramana, G V

    2017-05-01

    The article presents the stress-strain and volume change behavior, shear strength and stiffness parameters of landfilled municipal solid waste (MSW) collected from two dump sites located in Delhi, India. Over 30 drained triaxial compression (TXC) tests were conducted on reconstituted large-scale specimens of 150mm diameter to study the influence of fiber content, age, density and confining pressure on the shear strength of MSW. In addition, a few TXC tests were also conducted on 70mm diameter specimen to examine the effect of specimen size on the mobilized shear strength. It is observed that the fibrous materials such as textiles and plastics, and their percentage by weight have a significant effect on the stress-strain-volume change behavior, shear strength and stiffness of solid waste. The stress-strain-volume change behavior of MSW at Delhi is qualitatively in agreement with the behavior reported for MSW from different countries. Results of large-scale direct shear tests conducted on MSW with an identical composition used for TXC tests revealed the cross-anisotropic behavior as reported by previous researchers. Effective shear strength parameters of solid waste evaluated from this study is best characterized by ϕ'=39° and c'=0kPa for the limiting strain-based failure criteria of K0=0.3+5% axial strain and are in the range of the data reported for MSW from different countries. Data presented in this article is useful for the stress-deformation and stability analysis of the dump sites during their operation as well as closure plans. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Validation of the depression anxiety stress scales (DASS) 21 as a screening instrument for depression and anxiety in a rural community-based cohort of northern Vietnamese women

    National Research Council Canada - National Science Library

    Tran, Thach Duc; Tran, Tuan; Fisher, Jane

    2013-01-01

    .... The aim of this study was to validate the 21-item Depression Anxiety and Stress Scale (DASS21) for use in screening for these common mental disorders among rural women with young children in the North of Vietnam...

  3. From Detailed Description of Chemical Reacting Carbon Particles to Subgrid Models for CFD

    Directory of Open Access Journals (Sweden)

    Schulze S.

    2013-04-01

    Full Text Available This work is devoted to the development and validation of a sub-model for the partial oxidation of a spherical char particle moving in an air/steam atmosphere. The particle diameter is 2 mm. The coal particle is represented by moisture- and ash-free nonporous carbon while the coal rank is implemented using semi-global reaction rate expressions taken from the literature. The submodel includes six gaseous chemical species (O2, CO2, CO, H2O, H2, N2. Three heterogeneous reactions are employed, along with two homogeneous semi-global reactions, namely carbon monoxide oxidation and the water-gas-shift reaction. The distinguishing feature of the subgrid model is that it takes into account the influence of homogeneous reactions on integral characteristics such as carbon combustion rates and particle temperature. The sub-model was validated by comparing its results with a comprehensive CFD-based model resolving the issues of bulk flow and boundary layer around the particle. In this model, the Navier-Stokes equations coupled with the energy and species conservation equations were used to solve the problem by means of the pseudo-steady state approach. At the surface of the particle, the balance of mass, energy and species concentration was applied including the effect of the Stefan flow and heat loss due to radiation at the surface of the particle. Good agreement was achieved between the sub-model and the CFD-based model. Additionally, the CFD-based model was verified against experimental data published in the literature (Makino et al. (2003 Combust. Flame 132, 743-753. Good agreement was achieved between numerically predicted and experimentally obtained data for input conditions corresponding to the kinetically controlled regime. The maximal discrepancy (10% between the experiments and the numerical results was observed in the diffusion-controlled regime. Finally, we discuss the influence of the Reynolds number, the ambient O2 mass fraction and the ambient

  4. Revealing genome-scale transcriptional regulatory landscape of OmpR highlights its expanded regulatory roles under osmotic stress in Escherichia coli K-12 MG1655

    DEFF Research Database (Denmark)

    Seo, Sang Woo; Gao, Ye; Kim, Donghyuk

    2017-01-01

    A transcription factor (TF), OmpR, plays a critical role in transcriptional regulation of the osmotic stress response in bacteria. Here, we reveal a genome-scale OmpR regulon in Escherichia coli K-12 MG1655. Integrative data analysis reveals that a total of 37 genes in 24 transcription units (TUs...... discoveries related to stress responses....

  5. Child Behavior Checklist Juvenile Bipolar Disorder (CBCL-JBD) and CBCL Posttraumatic Stress Problems (CBCL-PTSP) Scales Are Measures of a Single Dysregulatory Syndrome

    Science.gov (United States)

    Ayer, Lynsay; Althoff, Robert; Ivanova, Masha; Rettew, David; Waxler, Ellen; Sulman, Julie; Hudziak, James

    2009-01-01

    Background: The Child Behavior Checklist Juvenile Bipolar Disorder (CBCL-JBD) profile and Posttraumatic Stress Problems (CBCL-PTSP) scale have been used to assess juvenile bipolar disorder (JBD) and posttraumatic stress disorder (PTSD), respectively. However, their validity is questionable according to previous research. Both measures are…

  6. Stress

    OpenAIRE

    Jensen, Line Skov; Lova, Lotte; Hansen, Zandra Kulikovsky; Schønemann, Emilie; Larsen, Line Lyngby; Colberg Olsen, Maria Sophia; Juhl, Nadja; Magnussen, Bogi Roin

    2012-01-01

    Stress er en tilstand som er meget omdiskuteret i samfundet, og dette besværliggør i en vis grad konkretiseringen af mulige løsningsforslag i bestræbelsen på at forebygge den såkaldte folkesygdom. Hovedkonklusionen er, at selv om der bliver gjort meget for at forebygge, er der ikke meget der aktivt kan sættes i værk for at reducere antallet af stressramte, før en fælles forståelse af stressårsager og effektiv stresshåndtering er fremlagt. Problemformuleringen er besvaret gennem en undersø...

  7. Integrative field scale phenotyping for investigating metabolic components of water stress within a vineyard

    Directory of Open Access Journals (Sweden)

    Jorge Gago

    2017-10-01

    Full Text Available Abstract Background There is currently a high requirement for field phenotyping methodologies/technologies to determine quantitative traits related to crop yield and plant stress responses under field conditions. Methods We employed an unmanned aerial vehicle equipped with a thermal camera as a high-throughput phenotyping platform to obtain canopy level data of the vines under three irrigation treatments. High-resolution imagery (< 2.5 cm/pixel was employed to estimate the canopy conductance (g c via the leaf energy balance model. In parallel, physiological stress measurements at leaf and stem level as well as leaf sampling for primary and secondary metabolome analysis were performed. Results Aerial g c correlated significantly with leaf stomatal conductance (g s and stem sap flow, benchmarking the quality of our remote sensing technique. Metabolome profiles were subsequently linked with g c and g s via partial least square modelling. By this approach malate and flavonols, which have previously been implicated to play a role in stomatal function under controlled greenhouse conditions within model species, were demonstrated to also be relevant in field conditions. Conclusions We propose an integrative methodology combining metabolomics, organ-level physiology and UAV-based remote sensing of the whole canopy responses to water stress within a vineyard. Finally, we discuss the general utility of this integrative methodology for broad field phenotyping.

  8. Multi-scale analysis of local flow topology in isotropic turbulence

    Science.gov (United States)

    Danish, Mohammad; Meneveau, Charles

    2017-11-01

    Knowledge of local flow-topology, as described by the velocity gradients, is useful to develop insights of turbulence processes, such as energy cascade, material element deformation, etc. Much has been learned in recent past about flow-topology at the smallest (viscous) scales of turbulence. However, less is known at larger (or inertial) scales of turbulence. In this work, we present a detailed study on the scale-dependence of various quantities of our interest, like population fraction of different flow-topologies, joint probability distribution of second and third invariants of velocity gradient tensor, etc. We use a new filter proposed by Eyink & Aluie to decompose the flow into small and large scales. We provide further insights for the observed behavior of scale-dependence by examining the probability fluxes appearing in the Fokker-Plank equation. Specifically, we aim to understand whether the differences observed between the viscous and inertial range are due to different effects caused by pressure, subgrid-scale or viscous stresses, or various combination thereof. For this purpose, we use the isotropic turbulence dataset at Reλ = 433 available at JHTDB and the analysis tools developed for SciServer, including FFT to evaluate filtering and gradients. Supported by the National Science Foundation (Grants No. 1507469 and 1633124).

  9. A scale invariance criterion for LES parametrizations

    Directory of Open Access Journals (Sweden)

    Urs Schaefer-Rolffs

    2015-01-01

    Full Text Available Turbulent kinetic energy cascades in fluid dynamical systems are usually characterized by scale invariance. However, representations of subgrid scales in large eddy simulations do not necessarily fulfill this constraint. So far, scale invariance has been considered in the context of isotropic, incompressible, and three-dimensional turbulence. In the present paper, the theory is extended to compressible flows that obey the hydrostatic approximation, as well as to corresponding subgrid-scale parametrizations. A criterion is presented to check if the symmetries of the governing equations are correctly translated into the equations used in numerical models. By applying scaling transformations to the model equations, relations between the scaling factors are obtained by demanding that the mathematical structure of the equations does not change.The criterion is validated by recovering the breakdown of scale invariance in the classical Smagorinsky model and confirming scale invariance for the Dynamic Smagorinsky Model. The criterion also shows that the compressible continuity equation is intrinsically scale-invariant. The criterion also proves that a scale-invariant turbulent kinetic energy equation or a scale-invariant equation of motion for a passive tracer is obtained only with a dynamic mixing length. For large-scale atmospheric flows governed by the hydrostatic balance the energy cascade is due to horizontal advection and the vertical length scale exhibits a scaling behaviour that is different from that derived for horizontal length scales.

  10. Evaluation of psychometric properties of the malay version perceived stress scale in two occupational settings in malaysia.

    Science.gov (United States)

    Al-Dubai, Sar; Ganasegeran, K; Barua, A; Rizal, Am; Rampal, Kg

    2014-07-01

    The 10-item version of Perceived Stress Scale (PSS-10) is a widely used tool to measure stress. The Malay version of the PSS-10 has been validated among Malaysian Medical Students. However, studies have not been conducted to assess its validity in occupational settings. The aim of this study is to assess the psychometric properties of the Malay version of the PSS-10 in two occupational setting in Malaysia. This study was conducted among 191 medical residents and 513 railway workers. An exploratory factor analysis was performed using the principal component method with varimax rotation. Correlation analyses, Kaiser-Meyer-Olkin, Bartlett's test of Sphericity and Cronbach's alpha were obtained. Statistical analysis was carried out using statistical package for the social sciences version 16 (SPSS, Chicago, IL, USA) software. Analysis yielded two factor structure of the Malay version of PSS-10 in both occupational groups. The two factors accounted for 59.2% and 64.8% of the variance in the medical residents and the railway workers respectively. Factor loadings were greater than 0.59 in both occupational groups. Cronbach's alpha co-efficient was 0.70 for medical residents and 0.71 for railway workers. The Malay version of PSS-10 had adequate psychometric properties and can be used to measure stress among occupational settings in Malaysia.

  11. Factor Structure and Reliability of the Malay Version of the Perceived Stress Scale among Malaysian Medical Students.

    Science.gov (United States)

    Al-Dubai, Sami Abdo Radman; Alshagga, Mustafa Ahmed; Rampal, Krishna Gopal; Sulaiman, Nik Aziz

    2012-07-01

    The Perceived Stress Scale 10 (PSS-10) is a validated and reliable instrument to measure global levels of perceived stress. This study aims to assess the internal consistency, reliability, and factor structure of the Malay version of the PSS-10 for use among medical students. The original English version of the PSS-10 was translated and back-translated into Malay language. The Malay version was distributed to 242 Bachelor of Medical Science students in a private university in Malaysia. Test-retest reliability was assessed in 70 students. An exploratory principal component factor analysis with varimax rotation was performed. Reliability was tested using the intraclass correlation coefficient (ICC). All 242 students participated in the initial questionnaire study (validity and factor structure), and 70 students participated in the test-retest reliability of the study. Exploratory factor analysis yielded 2 factors that accounted for 57.8% of the variance. Cronbach's alpha coefficients for the 2 factors were 0.85 and 0.70, respectively. The reliability test showed an ICC of 0.82 (95% CI: 0.70, 0.89). The Malay version of the PSS-10 showed adequate psychometric properties. It is a useful instrument for measuring stress among medical students in Malaysia.

  12. Topography on a subcellular scale modulates cellular adhesions and actin stress fiber dynamics in tumor associated fibroblasts

    Science.gov (United States)

    Azatov, Mikheil; Sun, Xiaoyu; Suberi, Alexandra; Fourkas, John T.; Upadhyaya, Arpita

    2017-12-01

    Cells can sense and adapt to mechanical properties of their environment. The local geometry of the extracellular matrix, such as its topography, has been shown to modulate cell morphology, migration, and proliferation. Here we investigate the effect of micro/nanotopography on the morphology and cytoskeletal dynamics of human pancreatic tumor-associated fibroblast cells (TAFs). We use arrays of parallel nanoridges with variable spacings on a subcellular scale to investigate the response of TAFs to the topography of their environment. We find that cell shape and stress fiber organization both align along the direction of the nanoridges. Our analysis reveals a strong bimodal relationship between the degree of alignment and the spacing of the nanoridges. Furthermore, focal adhesions align along ridges and form preferentially on top of the ridges. Tracking actin stress fiber movement reveals enhanced dynamics of stress fibers on topographically patterned surfaces. We find that components of the actin cytoskeleton move preferentially along the ridges with a significantly higher velocity along the ridges than on a flat surface. Our results suggest that a complex interplay between the actin cytoskeleton and focal adhesions coordinates the cellular response to micro/nanotopography.

  13. Genome-scale cold stress response regulatory networks in ten Arabidopsis thaliana ecotypes

    DEFF Research Database (Denmark)

    Barah, Pankaj; Jayavelu, Naresh Doni; Rasmussen, Simon

    2013-01-01

    BACKGROUND: Low temperature leads to major crop losses every year. Although several studies have been conducted focusing on diversity of cold tolerance level in multiple phenotypically divergent Arabidopsis thaliana (A. thaliana) ecotypes, genome-scale molecular understanding is still lacking. RE...

  14. In-situ determination of growth and thermal stresses in chromia scales formed on a ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Mougin, J.; Galerie, A.; Dupeux, M. [Laboratoire de Thermodynamique et de Physicochimie Metallurgiques, UMR 5614, Institut National Polytechnique de Grenoble, ENSEEG BP 75, F-38402 Saint Martin d' Heres (France); Rosman, N.; Lucazeau, G. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, UMR 5631, Institut National Polytechnique de Grenoble, ENSEEG BP 75, F-38402 Saint Martin d' Heres (France); Huntz, A.M. [Laboratoire d' Etude des Materiaux Hors Equilibre, UMR 8647 Universite de Paris-Sud, centre d' Orsay, F-91405 Orsay (France); Antoni, L. [Usinor Recherche et Developpement, Centre de Recherches d' Ugine, Avenue Paul Girod, F-73403 Ugine Cedex (France)

    2002-07-01

    In situ Raman spectroscopy experiments have been performed to determine both growth and thermal stresses of chromia scales formed at 750 C in oxygen on a stabilized ferritic stainless steel Fe-18Cr-TiNb. The measured growth stresses were shown to be highly compressive, near - 2 GPa. Cooling down and reheating cycles under inert gas showed that the thermal stresses were slightly compressive when cooling down (- 0.2 GPa), and reversible when heating up, showing their perfect thermo-elastic origin. Measurements, with temperature changes, of the deflection of oxidized samples after removal of one side oxide confirmed the Raman measurements and allowed to derive the actual value of the thermal expansion coefficient of the oxide scale: {alpha}{sub ox} = 10.75 x 10{sup -6} K{sup -1}. (Abstract Copyright[2002], Wiley Periodicals, Inc.) [German] In-situ Bestimmung von Wachstumsspannungen und thermischen Spannungen in Chromoxidzunder auf einem ferritischen nichtrostenden StahlIn-situ Ramanspektroskopieversuche wurden durchgefuehrt, um sowohl Wachstumsspannungen als auch thermische Spannungen von Chromoxidzunder, der sich bei 750 C in Sauerstoff auf einem stabilisierten, ferritischen nichtrostenden Stahl Fe-18Cr-TiNb gebildet hat, zu bestimmen. Die gemessenen Wachstumsspannungen waren hohe Druckspannungen, nahe - 2 GPa. Abkuehl- und Aufheizzyklen unter Inertgas zeigten, dass waehrend des Abkuehlens die thermischen Spannungen als schwache Druckspannungen (- 0,2 GPa) vorlagen, die beim Aufheizen reversibel waren und damit einen perfekten thermo-elastischen Ursprung aufwiesen. Die bei Temperaturaenderungen vorgenommenen Messungen der Durchbiegung der oxidierten Proben nach Entfernung einer Seite des Oxids bestaetigten die Ramanmessungen und erlaubten den aktuellen Wert des thermischen Expansionskoeffizienten des Oxidzunders herzuleiten: {alpha}{sub ox} = 10,75 x 10{sup -6} K{sup -1}. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  15. Versão resumida da "job stress scale": adaptação para o português Short version of the "job stress scale": a Portuguese-language adaptation

    Directory of Open Access Journals (Sweden)

    Márcia Guimarães de Mello Alves

    2004-04-01

    Full Text Available OBJETIVO: Descrever o processo de adaptação, para o português, da versão resumida da "job stress scale", originalmente elaborada em inglês. MÉTODOS: Foram avaliados seis aspectos de equivalência entre a escala original e a versão para o português: as equivalências conceitual, semântica, operacional, de itens, de medidas e funcional. Tomou-se por base um estudo de confiabilidade teste-reteste com 94 indivíduos selecionados. RESULTADOS: O estudo de confiabilidade teste-reteste entre 94 indivíduos permitiu estimativas de reprodutibilidade (coeficientes de correlação intraclasse para as dimensões de "demanda", "controle" e "apoio social" da escala de 0,88, 0,87 e 0,85, respectivamente. Para as mesmas dimensões, as estimativas de consistência interna (alpha de Cronbach foram, respectivamente, 0,79, 0,67 e 0,85. CONCLUSÕES: Os resultados sugerem que o processo de adaptação da escala foi bem sucedido, indicando que seu uso no contexto sociocultural da população de estudo (Estudo Pró-Saúde é apropriado.OBJECTIVE: To describe the adaptation to Portuguese of the short version of the "job stress scale", originally in English. METHODS: We evaluate six aspects of equivalence between the original scale and the Portuguese version: conceptual, semantic, operational, item, measurement, and functional equivalences. A reliability test-retest study was conducted with 94 selected subjects. RESULTS: Reproducibility (interclass correlation coefficients for the 'demand', 'control', and 'social support' dimensions of the scale was estimated at 0.88, 0.87, and 0.85, respectively. Internal consistency (Cronbach's alpha estimates for these same dimensions were 0.79, 0.67, and 0.85, respectively. CONCLUSIONS: Our results suggest that the adaptation of the scale was successful, and indicate that its use in the sociocultural context of the studied population (Pró-Saúde survey is appropriate.

  16. Development and Validation of the Coping with Acculturative Stress in American Schools (Casas-A) Scale on a Latino Adolescent Sample

    Science.gov (United States)

    Castro-Olivo, Sara M.; Palardy, Gregory J.; Albeg, Loren; Williamson, Ariel A.

    2014-01-01

    The psychometric properties of the Coping With Acculturative Stress in American Schools (CASAS-A) scale were examined using a sample of 148 Latino middle school students. CASAS-A is a self-report scale designed to identify students in need of culturally responsive social-emotional interventions due to having high levels of school-related…

  17. Psychometric properties of the Perceived Stress Scale (PSS): measurement invariance between athletes and non-athletes and construct validity

    Science.gov (United States)

    Lin, Ju-Han; Nien, Chiao-Lin; Hsu, Ya-Wen; Liu, Hong-Yu

    2016-01-01

    Background Although Perceived Stress Scale (PSS, Cohen, Kamarack & Mermelstein, 1983) has been validated and widely used in many domains, there is still no validation in sports by comparing athletes and non-athletes and examining related psychometric indices. Purpose The purpose of this study was to examine the measurement invariance of PSS between athletes and non-athletes, and examine construct validity and reliability in the sports contexts. Methods Study 1 sampled 359 college student-athletes (males = 233; females = 126) and 242 non-athletes (males = 124; females = 118) and examined factorial structure, measurement invariance and internal consistency. Study 2 sampled 196 student-athletes (males = 139, females = 57, Mage = 19.88 yrs, SD = 1.35) and examined discriminant validity and convergent validity of PSS. Study 3 sampled 37 student-athletes to assess test-retest reliability of PSS. Results Results found that 2-factor PSS-10 fitted the model the best and had appropriate reliability. Also, there was a measurement invariance between athletes and non-athletes; and PSS positively correlated with athletic burnout and life stress but negatively correlated with coping efficacy provided evidence of discriminant validity and convergent validity. Further, the test-retest reliability for PSS subscales was significant (r = .66 and r = .50). Discussion It is suggested that 2-factor PSS-10 can be a useful tool in assessing perceived stress either in sports or non-sports settings. We suggest future study may use 2-factor PSS-10 in examining the effects of stress on the athletic injury, burnout, and psychiatry disorders. PMID:27994983

  18. Psychometric properties of the Perceived Stress Scale (PSS): measurement invariance between athletes and non-athletes and construct validity.

    Science.gov (United States)

    Chiu, Yi-Hsiang; Lu, Frank Jing-Horng; Lin, Ju-Han; Nien, Chiao-Lin; Hsu, Ya-Wen; Liu, Hong-Yu

    2016-01-01

    Although Perceived Stress Scale (PSS, Cohen, Kamarack & Mermelstein, 1983) has been validated and widely used in many domains, there is still no validation in sports by comparing athletes and non-athletes and examining related psychometric indices. The purpose of this study was to examine the measurement invariance of PSS between athletes and non-athletes, and examine construct validity and reliability in the sports contexts. Study 1 sampled 359 college student-athletes (males = 233; females = 126) and 242 non-athletes (males = 124; females = 118) and examined factorial structure, measurement invariance and internal consistency. Study 2 sampled 196 student-athletes (males = 139, females = 57, Mage = 19.88 yrs, SD = 1.35) and examined discriminant validity and convergent validity of PSS. Study 3 sampled 37 student-athletes to assess test-retest reliability of PSS. Results found that 2-factor PSS-10 fitted the model the best and had appropriate reliability. Also, there was a measurement invariance between athletes and non-athletes; and PSS positively correlated with athletic burnout and life stress but negatively correlated with coping efficacy provided evidence of discriminant validity and convergent validity. Further, the test-retest reliability for PSS subscales was significant (r = .66 and r = .50). It is suggested that 2-factor PSS-10 can be a useful tool in assessing perceived stress either in sports or non-sports settings. We suggest future study may use 2-factor PSS-10 in examining the effects of stress on the athletic injury, burnout, and psychiatry disorders.

  19. Psychometric properties of the Perceived Stress Scale (PSS: measurement invariance between athletes and non-athletes and construct validity

    Directory of Open Access Journals (Sweden)

    Yi-Hsiang Chiu

    2016-12-01

    Full Text Available Background Although Perceived Stress Scale (PSS, Cohen, Kamarack & Mermelstein, 1983 has been validated and widely used in many domains, there is still no validation in sports by comparing athletes and non-athletes and examining related psychometric indices. Purpose The purpose of this study was to examine the measurement invariance of PSS between athletes and non-athletes, and examine construct validity and reliability in the sports contexts. Methods Study 1 sampled 359 college student-athletes (males = 233; females = 126 and 242 non-athletes (males = 124; females = 118 and examined factorial structure, measurement invariance and internal consistency. Study 2 sampled 196 student-athletes (males = 139, females = 57, Mage = 19.88 yrs, SD = 1.35 and examined discriminant validity and convergent validity of PSS. Study 3 sampled 37 student-athletes to assess test-retest reliability of PSS. Results Results found that 2-factor PSS-10 fitted the model the best and had appropriate reliability. Also, there was a measurement invariance between athletes and non-athletes; and PSS positively correlated with athletic burnout and life stress but negatively correlated with coping efficacy provided evidence of discriminant validity and convergent validity. Further, the test-retest reliability for PSS subscales was significant (r = .66 and r = .50. Discussion It is suggested that 2-factor PSS-10 can be a useful tool in assessing perceived stress either in sports or non-sports settings. We suggest future study may use 2-factor PSS-10 in examining the effects of stress on the athletic injury, burnout, and psychiatry disorders.

  20. Probing Stochastic Nano-Scale Inelastic Events in Stressed Amorphous Metal

    Science.gov (United States)

    Yang, Y.; Fu, X. L.; Wang, S.; Liu, Z. Y.; Ye, Y. F.; Sun, B. A.; Liu, C. T.

    2014-10-01

    One fundamental yet longstanding issue in materials science is how local inelasticity arises within an amorphous structure before yielding occurs. Although many possible scenarios were postulated or predicted by theories and simulations,however, direct experimental evidence has been lacking today due to the lack of a sensitive way to detect nano-scale inelasticity. Through the carefully designed microcompression method as coupled with the state-of-art nano-scale electric resistance measurement, we here unfold a stochastic inelastic deformation process in a Zr-based metallic glass, which takes place via the recurrence of two types of short-lived inelastic events causing structural damage and recovery, respectively, prior to yielding. Our current findings reveal that these stochastic events not only self-organize into sub-critical events due to elastic coupling, but also compete with each other in a way that enables the whole amorphous structure to self-heal as well as to sustain local damage.

  1. Deriving the Characteristic Scale for Effectively Monitoring Heavy Metal Stress in Rice by Assimilation of GF-1 Data with the WOFOST Model.

    Science.gov (United States)

    Huang, Zhi; Liu, Xiangnan; Jin, Ming; Ding, Chao; Jiang, Jiale; Wu, Ling

    2016-03-07

    Accurate monitoring of heavy metal stress in crops is of great importance to assure agricultural productivity and food security, and remote sensing is an effective tool to address this problem. However, given that Earth observation instruments provide data at multiple scales, the choice of scale for use in such monitoring is challenging. This study focused on identifying the characteristic scale for effectively monitoring heavy metal stress in rice using the dry weight of roots (WRT) as the representative characteristic, which was obtained by assimilation of GF-1 data with the World Food Studies (WOFOST) model. We explored and quantified the effect of the important state variable LAI (leaf area index) at various spatial scales on the simulated rice WRT to find the critical scale for heavy metal stress monitoring using the statistical characteristics. Furthermore, a ratio analysis based on the varied heavy metal stress levels was conducted to identify the characteristic scale. Results indicated that the critical threshold for investigating the rice WRT in monitoring studies of heavy metal stress was larger than 64 m but smaller than 256 m. This finding represents a useful guideline for choosing the most appropriate imagery.

  2. Large Eddy Simulation of an SD7003 Airfoil: Effects of Reynolds number and Subgrid-scale modeling

    DEFF Research Database (Denmark)

    Sarlak Chivaee, Hamid

    2017-01-01

    This paper presents results of a series of numerical simulations in order to study aerodynamic characteristics of the low Reynolds number Selig-Donovan airfoil, SD7003. Large Eddy Simulation (LES) technique is used for all computations at chord-based Reynolds numbers 10,000, 24,000 and 60...

  3. Entropy Stress and Scaling of Vital Organs over Life Span Based on Allometric Laws

    Directory of Open Access Journals (Sweden)

    Carlos Silva

    2012-12-01

    Full Text Available Abstract: Past theories on total lifetime energy expenditures and entropy generation in biological systems (BS dealt with whole systems, but the recent literature suggests that the total metabolic rate of a BS,q̇body (W is a sum of product of specific metabolic rate q̇k,m (W/kg of organ k of each vital life organ, k {k = brain, heart, kidney and liver, or abbreviated as BHKL, and rest of the organ mass (R} and mass of each organ k (mk. Using this hypothesis, Kleiber’s law on metabolic rate of BS (q̇body for animals of different sizes was validated. In this work, a similar procedure is adopted in estimating total entropy generation rate of whole human body (σ̇body, W/K as a sum of product of specific entropy generation rate for each organ, σ̇k,m (W/{K kg of organ k·} and the organ mass at any given age (t. Further integrating over life span for each organ (tlife, the lifetime specific entropy generated by organ k, σk,m,life (J of organ k/ {K kg organ k} is calculated. Then lifetime entropy generation of unit body mass, σbody,M,life (J/{K kg body mass·} is calculated as a sum of the corresponding values contributed by all vital organs to unit body mass and verified with previously published literature. The higher the σk,m,life , the higher the entropy stress level (which is a measure of energy released by unit organ mass of k as heat and the irreversibility within the organ, resulting in faster degradation of organ and the consequent health problems for the whole BS. In order to estimate σ̇k (W/K of organ k, data on energy release rate (q̇ is needed over lifetime for each organ. While the Adequate Macronutrients Distribution Range (AMDR/Adequate Intake (AI publication can be used in estimating the energy intake of whole body vs. age for the human body, the energy expenditure data is not available at organ level. Hence the σk,m,life was computed using existing allometric laws developed for the metabolism of the organs, the

  4. Adaptation to Portuguese of the Depression, Anxiety and Stress Scales (DASS Adaptación para la lengua portuguesa de la Depression, Anxiety and Stress Scale (DASS Adaptação para a língua portuguesa da Depression, Anxiety and Stress Scale (DASS

    Directory of Open Access Journals (Sweden)

    João Luís Alves Apóstolo

    2006-12-01

    Full Text Available Objective: to adapt to Portuguese, of Portugal, the Depression, Anxiety and Stress Scales, a 21-item short scale (DASS 21, designed to measure depression, anxiety and stress. Method: After translation and back-translation with the help of experts, the DASS 21 was administered to patients in external psychiatry consults (N=101, and its internal consistency, construct validity and concurrent validity were measured. Results: The DASS 21 properties certify its quality to measure emotional states. The instrument reveals good internal consistency. Factorial analysis shows that the two-factor structure is more adequate. The first factor groups most of the items that theoretically assess anxiety and stress, and the second groups most of the items that assess depression, explaining, on the whole, 58.54% of total variance. The strong positive correlation between the DASS 21 and the Hospital Anxiety and Depression scale (HAD confirms the hypothesis regarding the criterion validity, however, revealing fragilities as to the divergence between theoretically different constructs.Objetivo: adaptar a la lengua portuguesa, de Portugal, la Depression, Anxiety and Stress Scale, versión corta de 21 ítems, (DASS-21, que permite evaluar depresión, ansiedad y estrés. Método: Después de haber sido traducida y retrovertida, con la ayuda de peritos, la DASS-21 fue administrada a enfermos en consulta externa de psiquiatría (N=101, y fue evaluada la consistencia interna, la validez de constructo y la validez concurrente. Resultados: Las propiedades de la DASS-21 atestiguan su calidad para evaluar estados emocionales. El instrumento reveló buena consistencia interna. El análisis factorial muestra que la estructura de dos factores es la más ajustada. El primer factor agrupa la mayoría de los ítems que teóricamente evalúan ansiedad y estrés, y el segundo agrupa la mayoría de los ítems que evalúan depresión, explicando en su conjunto el 58,54% de la variaci

  5. More than a (negative feeling: Validity of the perceived stress scale in Serbian clinical and non-clinical samples

    Directory of Open Access Journals (Sweden)

    Jovanović Veljko

    2015-01-01

    Full Text Available The goal of the present study was to test the validity of a Serbian version of the Perceived Stress Scale. The PSS was administered to 157 psychiatric outpatients, 165 adults from the non-clinical population, and 283 university students. The results of the confirmatory factor analysis supported a bifactor model of the PSS with one general factor and two specific factors reflecting perceived distress and perceived self-efficacy. Internal consistencies of the scale and its two subscales were adequate across clinical and non-clinical samples. Results supported the ability of the scale to discriminate between clinical and non-clinical samples. The PSS evidenced good convergent validity, showing moderate to high positive correlations with measures of unpleasant emotional states and moderate negative correlations with positive affect and life satisfaction. All but one correlation remained significant after controlling for the measures of emotional distress. The results of the present research support validity of the PSS and its use in both clinical and non-clinical samples. [Projekat Ministarstva nauke Republike Srbije, br. 179006

  6. Measuring Multiple Minority Stress: The LGBT People of Color Microaggressions Scale

    Science.gov (United States)

    Balsam, Kimberly F.; Molina, Yamile; Beadnell, Blair; Simoni, Jane; Walters, Karina

    2014-01-01

    Lesbian, gay, and bisexual individuals who are also racial/ethnic minorities (LGBT-POC) are a multiply marginalized population subject to microaggressions associated with both racism and heterosexism. To date, research on this population has been hampered by the lack of a measurement tool to assess the unique experiences associated with the intersection of these oppressions. To address this gap in the literature, we conducted a three-phase, mixed method empirical study to assess microaggressions among LGBT-POC. The LGBT People of Color Microaggressions Scale is an 18-item self-report scale assessing the unique types of microaggressions experienced by ethnic minority LGBT adults. The measure includes three subscales: (a) Racism in LGBT communities, (b) Heterosexism in Racial/Ethnic Minority Communities, and (c) Racism in Dating and Close Relationships, that are theoretically consistent with prior literature on racial/ethnic minority LGBTs and have strong psychometric properties including internal consistency and construct validity in terms of correlations with measures of psychological distress and LGBT-identity variables. Men scored higher on the LGBT-PCMS than women, lesbians and gay men scored higher than bisexual women and men, and Asian Americans scored higher than African Americans and Latina/os. PMID:21604840

  7. Stress distribution retrieval in granular materials: A multi-scale model and digital image correlation measurements

    Science.gov (United States)

    Bruno, Luigi; Decuzzi, Paolo; Gentile, Francesco

    2016-01-01

    The promise of nanotechnology lies in the possibility of engineering matter on the nanoscale and creating technological interfaces that, because of their small scales, may directly interact with biological objects, creating new strategies for the treatment of pathologies that are otherwise beyond the reach of conventional medicine. Nanotechnology is inherently a multiscale, multiphenomena challenge. Fundamental understanding and highly accurate predictive methods are critical to successful manufacturing of nanostructured materials, bio/mechanical devices and systems. In biomedical engineering, and in the mechanical analysis of biological tissues, classical continuum approaches are routinely utilized, even if these disregard the discrete nature of tissues, that are an interpenetrating network of a matrix (the extra cellular matrix, ECM) and a generally large but finite number of cells with a size falling in the micrometer range. Here, we introduce a nano-mechanical theory that accounts for the-non continuum nature of bio systems and other discrete systems. This discrete field theory, doublet mechanics (DM), is a technique to model the mechanical behavior of materials over multiple scales, ranging from some millimeters down to few nanometers. In the paper, we use this theory to predict the response of a granular material to an external applied load. Such a representation is extremely attractive in modeling biological tissues which may be considered as a spatial set of a large number of particulate (cells) dispersed in an extracellular matrix. Possibly more important of this, using digital image correlation (DIC) optical methods, we provide an experimental verification of the model.

  8. Stress.

    Science.gov (United States)

    Chambers, David W

    2008-01-01

    We all experience stress as a regular, and sometimes damaging and sometimes useful, part of our daily lives. In our normal ups and downs, we have our share of exhaustion, despondency, and outrage--matched with their corresponding positive moods. But burnout and workaholism are different. They are chronic, dysfunctional, self-reinforcing, life-shortening habits. Dentists, nurses, teachers, ministers, social workers, and entertainers are especially susceptible to burnout; not because they are hard-working professionals (they tend to be), but because they are caring perfectionists who share control for the success of what they do with others and perform under the scrutiny of their colleagues (they tend to). Workaholics are also trapped in self-sealing cycles, but the elements are ever-receding visions of control and using constant activity as a barrier against facing reality. This essay explores the symptoms, mechanisms, causes, and successful coping strategies for burnout and workaholism. It also takes a look at the general stress response on the physiological level and at some of the damage American society inflicts on itself.

  9. Validação da escala de estresse no trabalho Validation of the work stress scale

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    Tatiane Paschoal

    2004-04-01

    Full Text Available Este trabalho teve como objetivo construir e validar um instrumento de estresse ocupacional geral, de fácil aplicação e que pudesse ser utilizado em diversos ambientes de trabalho e para ocupações variadas. A Escala de Estresse no Trabalho (EET, inicialmente composta por 31 itens, foi aplicada a 437 trabalhadores de diferentes organizações, públicas e privadas, sendo 249 homens e 188 mulheres. A análise fatorial revelou a existência de um único fator que, após eliminação de itens com carga fatorial abaixo de 0,45, ficou composto por 23 itens e obteve um coeficiente alfa de Cronbach equivalente a 0,91. Uma versão reduzida da escala, com 13 itens e alfa de 0,85 foi proposta. Com base nos parâmetros psicométricos satisfatórios da EET, conclui-se que esta é uma alternativa para investigações empíricas e trabalhos aplicados em organizações, podendo orientar medidas que visem à qualidade de vida dos trabalhadores.The objective of this study was to develop and to validate a general instrument to evaluate occupational stress, easily administered, used in different work environments and for a variety of occupations. The Work Stress Scale (WSS initially composed of 31 items was applied to 437 workers, 249 men and 188 women, of public and private organizations. The factor analysis detected only one factor. After the elimination of the items with a factor loading below .45, the final version of the scale was composed of 23 items and had a Cronbach's coefficient of .91. A reduced version of the scale with 13 items and a Cronbach's coefficient of .85 has been proposed. Based on the satisfactory psychometric parameters of the scale, it is concluded that the WSS is useful as an alternative in empirical investigations and organizational diagnostics. The results obtained can be useful indicators for organizational decisions in relation to the life quality of the workers.

  10. Post-traumatic stress symptoms in cancer survivors: relationship to the impact of cancer scale and other associated risk factors.

    Science.gov (United States)

    Hahn, Erin E; Hays, Ron D; Kahn, Katherine L; Litwin, Mark S; Ganz, Patricia A

    2015-06-01

    The purpose of this study was to determine the prevalence of post-traumatic stress symptoms in a sample of cancer survivors and to investigate their association with the impact of cancer, depressive symptoms, and social support. We administered a survey to participants in a cancer survivor registry. It included: Post-Traumatic Stress Disorder Checklist-Civilian version (PCL-C), Impact of Cancer Scale (IOC) v.2, and measures of social support, income, and long-term effects of cancer. We performed multivariate analyses to estimate associations between PCL-C and other variables. PCL-C score was examined as a continuous dependent variable and categorically. Responses were available from 162 cancer survivors. Mean age was 51 years (standard deviation (SD) 16); mean time since diagnosis was 11 years (SD 10). Mean PCL-C score was 27 (SD 9, range 17-64); 29% of the sample scored 30 and above, 13% scored 38 and above, 7% scored 44 and above. Linear regression indicated that PCL-C scores were significantly associated with the IOC negative impact summary scale (NIS) (p symptoms (p = 0.003), less social support (p = 0.02), and lower income (p = 0.03). NIS subscale analyses showed that two subscales, life interference (LI) and worry (W), were significantly correlated with PCL-C score (LI: p symptoms. Assessing survivors for PTSD symptoms with the PCL-C could detect those individuals in need of psychosocial support. The IOC may be useful for identifying target areas for interventions to reduce these symptoms among cancer survivors. Copyright © 2014 John Wiley & Sons, Ltd.

  11. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale

    Science.gov (United States)

    Hossain, R.; Pahlevani, F.; Quadir, M. Z.; Sahajwalla, V.

    2016-10-01

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels’ performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.

  12. A Subgrid Parameterization for Wind Turbines in Weather Prediction Models with an Application to Wind Resource Limits

    Directory of Open Access Journals (Sweden)

    B. H. Fiedler

    2014-01-01

    Full Text Available A subgrid parameterization is offered for representing wind turbines in weather prediction models. The parameterization models the drag and mixing the turbines cause in the atmosphere, as well as the electrical power production the wind causes in the wind turbines. The documentation of the parameterization is complete; it does not require knowledge of proprietary data of wind turbine characteristics. The parameterization is applied to a study of wind resource limits in a hypothetical giant wind farm. The simulated production density was found not to exceed 1 W m−2, peaking at a deployed capacity density of 5 W m−2 and decreasing slightly as capacity density increased to 20 W m−2.

  13. Damage assessment in the stress field of scale, comparability and transferability

    Directory of Open Access Journals (Sweden)

    Assmann André

    2016-01-01

    Full Text Available Damage assessment is an important task requested in very different contexts. On the one hand very detailed studies are required for cost benefit analysis, on the other hand vulnerability and risk needs to be evaluated for political decisions and emergency situations (i.e. loss estimation of a large scale flood event. Even though a lot of studies have been performed and a lot of different methods are available by now, it is very difficult to use the results in the decision making process, as many methods are poorly described or are based on very special data, and therefore cannot be compared to each other. The attempt of regional (German federal state level standardizations based on very detailed object based approaches are shown. Additionally, a European wide data set for asset mapping is described and a set of application examples is given. It is designed to enable users to compare the impact of different types of hazard. To take it one step further, a global map for vulnerability is presented that can be used to set up a monetary based data set if detailed statistical data is not available. Every type of data set and methodology has its special tasks to fulfil but there is also a high demand for harmonisation and comparability between different studies to enable better decision making. The next demand on data sets and methodologies is to perform time sequence analyses, therefore all data sets and methods presented fulfil the requirement of being updated regularly.

  14. Surface stress and large-scale self-organization at organic-metal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian

    2009-01-22

    The role of elastic interactions, particularly for the self-organized formation of periodically faceted interfaces, was investigated in this thesis for archetype organic-metal interfaces. The cantilever bending technique was applied to study the change of surface stress upon formation of the interface between 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and Ag(111). The main focus of this work was on the investigation of the formation of the long-range ordered, self-organized faceted PTCDA/Ag(10 8 7) interface. Reciprocal space maps of this interface were recorded both by spot profile analysis low energy electron diffraction (SPA-LEED) and low energy electron microscopy (LEEM) in selected area LEED mode. Complementary to the reciprocal data, also microscopic real-space LEEM data were used to characterize the morphology of this interface. Six different facet faces ((111), (532), (743), (954), (13 9 5), and (542)) were observed for the preparation path of molecular adsorption on the substrate kept at 550 K. Facet-sensitive dark-field LEEM localized these facets to grow in homogeneous areas of microscopic extensions. The temperature-dependence of the interface formation was studied in a range between 418 K and 612 K in order to learn more about the kinetics of the process. Additional steeper facets of 27 inclination with respect to the (111) surface were observed in the low temperature regime. Furthermore, using facet-sensitive dark-field LEEM, spatial and size distributions of specific facets were studied for the different temperatures. Moreover, the facet dimensions were statistically analyzed. The total island size of the facets follows an exponential distribution, indicating a random growth mode in absence of any mutual facet interactions. While the length distribution of the facets also follows an exponential distribution, the width distribution is peaked, reflecting the high degree of lateral order. This anisotropy is temperature-dependent and occurs

  15. Continuous evapotranspiration monitoring and water stress at watershed scale in a Mediterranean oak savanna

    Science.gov (United States)

    Carpintero, E.; González Dugo, M. P.; Hain, C.; Nieto, H.; Gao, F.; Andreu, A.; Kustas, W. P.; Anderson, M. C.

    2016-10-01

    The regular monitoring of the evapotranspiration rates and their links with vegetation conditions and soil moisture may support management and hydrological planning leading to reduce the economic and environmental vulnerability of complex water-controlled Mediterranean ecosystems. In this work, the monitoring of water use over a basin with a predominant oak savanna (known in Spain as dehesa) was conducted for two years, 2013 and 2014, monitoring ET at both fine spatial and temporal resolution in different seasons. A global 5 km daily ET product, developed with the ALEXI model and MODIS day-night temperature difference, was used as starting point. Flux estimations with higher spatial resolutions were obtained with the associated flux disaggregation scheme, DisALEXI, using surface temperature data from the polar orbiting satellites MODIS (1 Km, daily) and Landsat 7/8 (60-120m and sharpened to 30m, 16 days) and the previously estimated coarse resolution fluxes. The results achieved supported the ability of this scheme to accurately estimate daytime-integrated energy fluxes over this system, using input data with different spatio-temporal resolution and without the need for ground observations. Daily ET series at 30 m spatial resolution, generated using STARFM fusion technique, has provided a significant improvement in spatial heterogeneity assessment of the ET series, with RMSE values of 0.56 and 0.68 mm/day for each year, representing an enhancement with respect to interpolated Landsat series. In summary, this approach was demostrated to be robust and operative to map ET at watershed scale with a suitable spatial and temporal resolution for applications over the dehesa ecosystem.

  16. Positive and negative affect within the realm of depression, stress and fatigue: the two-factor distress model of the Global Mood Scale (GMS).

    Science.gov (United States)

    Denollet, Johan; De Vries, Jolanda

    2006-04-01

    The Global Mood Scale (GMS; [Denollet, J., 1993a. Emotional distress and fatigue in coronary heart disease: the Global Mood Scale (GMS). Psychol Med 23, 111-121., Denollet, J., 1993b. The sensitivity of outcome assessment in cardiac rehabilitation. J Consult Clin Psychol 61, 686-695.]) was originally developed as a measure of positive affect (PA) and negative affect (NA) in cardiac patients. The purpose of this study was to examine its two-factor affect model in the realm of stress, depression, and fatigue in working adults. Affect, stress, depression, and fatigue were assessed with validated questionnaires in a sample of 228 adults (49.6% male; mean = 41.4 +/- 9 years) from the working population. The GMS PA and NA scales were internally consistent (Cronbach's alpha = .94 and alpha = .93, respectively), and correlated in the expected direction with their corresponding mood scales from the Positive and Negative Affect Schedule (PANAS). Factor analyses of the 40 mood terms comprising the GMS and PANAS yielded one common PA-dimension, but two NA-dimensions reflecting emotional exhaustion (GMS) and anxious apprehension (PANAS) as different components of the stress process. A relatively high mean NA score of the GMS suggested that these working adults perceived terms that refer to malaise/deactivation as being relevant to describe their negative affective status. The GSM-NA scale was related to stress, depression and fatigue while the GMS-PA scale was positively associated with quality of life. This study is based on a cross-sectional design. The association between the PA (negative correlation) and NA (positive correlation) scales of the GMS and perceived stress, depressive symptoms, and fatigue supports the validity of its two-factor model. Assessment of both PA and NA may benefit a better understanding of emotional distress in adults from the working population.

  17. Assessment of the validity and reliability for a newly developed Stress in Academic Life Scale (SALS) for pharmacy undergraduates

    OpenAIRE

    Ali Yousif Alzaeem; Syed Azhar Syed Sulaiman; Wasif Gillani

    2010-01-01

    Background & Objectives: Stress results from perception of individual to external threats. Stress in academic life affects all college students regardless of their programs. It has been well established in many studies that pharmacy students suffer a massy amount of stress but empirical evidence with regard to how much stress affects pharmacy students and how they cope with it is still needed. The present paper vows constructing a special tool to be used in gauging stress of pharmacy undergra...

  18. Simulation of subgrid orographic precipitation with an embedded 2-D cloud-resolving model

    Science.gov (United States)

    Jung, Joon-Hee; Arakawa, Akio

    2016-03-01

    By explicitly resolving cloud-scale processes with embedded two-dimensional (2-D) cloud-resolving models (CRMs), superparameterized global atmospheric models have successfully simulated various atmospheric events over a wide range of time scales. Up to now, however, such models have not included the effects of topography on the CRM grid scale. We have used both 3-D and 2-D CRMs to simulate the effects of topography with prescribed "large-scale" winds. The 3-D CRM is used as a benchmark. The results show that the mean precipitation can be simulated reasonably well by using a 2-D representation of topography as long as the statistics of the topography such as the mean and standard deviation are closely represented. It is also shown that the use of a set of two perpendicular 2-D grids can significantly reduce the error due to a 2-D representation of topography.

  19. La versión castellana de la escala "the nursing stress scale". proceso de adaptación transcultural

    Directory of Open Access Journals (Sweden)

    Más Pons Rosa

    1998-01-01

    Full Text Available FUNDAMENTO: Adaptación transcultural de la escala de medida de estresores laborales en personal de enfermería hospitalario "The Nursing Stress Scale". MÉTODOS: Se ha utilizado el método de traducción-retrotraducción complementado con metodología cualitativa (grupos de discusión. La escala original fue traducida al castellano de forma independiente por dos enfermeras bilingües de origen español que habían residido en Estados Unidos. A continuación se llevó a cabo la retrotraducción al inglés por dos traductores de origen norteamericano residentes en España. Se realizaron 2 grupos de discusión; uno compuesto por enfermeras/os y otro por auxiliares de enfermería de distintos servicios y hospitales. Por último, se realizó una encuesta piloto en 20 profesionales de enfermería. RESULTADOS: Los ítems fueron clasificados según la dificultad en encontrar una expresión en castellano conceptualmente equivalente a la original; 15 ítems no presentaron ninguna dificultad, en 13 ítems fue moderada y en 6 alta. Tras una nueva traducción de los ítems problemáticos y las consultas realizadas a uno de los autores de la escala original, se obtuvo una versión en castellano en la que 12 ítems presentaban dos o más versiones alternativas, que fueron valoradas posteriormente en la encuesta piloto. Como resultado de los grupos de discusión se concluyó que los estresores laborales percibidos por el personal de enfermería son equiparables a los contenidos en la escala original exceptuando el ítem "Avería del ordenador" que no resulta procedente en nuestro medio. CONCLUSIÓN: Se ha obtenido una versión adaptada en castellano de la escala The Nursing Stress Scale, siendo necesaria la evaluación posterior de su validez y fiabilidad.

  20. Analysis of Suicidal Behaviour in Israeli Veterans and Terror Victims with Post-Traumatic Stress Disorder by Using the Computerised Gottschalk-Gleser Scales

    Science.gov (United States)

    Galor, Sharon; Hentschel, Uwe

    2009-01-01

    The primary objective of this study was to identify the vulnerability factors for suicide attempts in an Israeli sample, with the help of the Gottschalk-Gleser content analysis scales. The respondents were divided into four groups: suicide attempters; controls; post-traumatic stress disorder and depressed patients who did not report suicidal…

  1. An investigation of the sub-grid variability of trace gases and aerosols for global climate modeling

    Directory of Open Access Journals (Sweden)

    Y. Qian

    2010-07-01

    Full Text Available One fundamental property and limitation of grid based models is their inability to identify spatial details smaller than the grid cell size. While decades of work have gone into developing sub-grid treatments for clouds and land surface processes in climate models, the quantitative understanding of sub-grid processes and variability for aerosols and their precursors is much poorer. In this study, WRF-Chem is used to simulate the trace gases and aerosols over central Mexico during the 2006 MILAGRO field campaign, with multiple spatial resolutions and emission/terrain scenarios. Our analysis focuses on quantifying the sub-grid variability (SGV of trace gases and aerosols within a typical global climate model grid cell, i.e. 75×75 km2.

    Our results suggest that a simulation with 3-km horizontal grid spacing adequately reproduces the overall transport and mixing of trace gases and aerosols downwind of Mexico City, while 75-km horizontal grid spacing is insufficient to represent local emission and terrain-induced flows along the mountain ridge, subsequently affecting the transport and mixing of plumes from nearby sources. Therefore, the coarse model grid cell average may not correctly represent aerosol properties measured over polluted areas. Probability density functions (PDFs for trace gases and aerosols show that secondary trace gases and aerosols, such as O3, sulfate, ammonium, and nitrate, are more likely to have a relatively uniform probability distribution (i.e. smaller SGV over a narrow range of concentration values. Mostly inert and long-lived trace gases and aerosols, such as CO and BC, are more likely to have broad and skewed distributions (i.e. larger SGV over polluted regions. Over remote areas, all trace gases and aerosols are more uniformly distributed compared to polluted areas. Both CO and O3 SGV vertical profiles are nearly constant within the PBL during daytime, indicating that trace gases

  2. Renormalization-group theory for the eddy viscosity in subgrid modeling

    Science.gov (United States)

    Zhou, YE; Vahala, George; Hossain, Murshed

    1988-01-01

    Renormalization-group theory is applied to incompressible three-dimensional Navier-Stokes turbulence so as to eliminate unresolvable small scales. The renormalized Navier-Stokes equation now includes a triple nonlinearity with the eddy viscosity exhibiting a mild cusp behavior, in qualitative agreement with the test-field model results of Kraichnan. For the cusp behavior to arise, not only is the triple nonlinearity necessary but the effects of pressure must be incorporated in the triple term. The renormalized eddy viscosity will not exhibit a cusp behavior if it is assumed that a spectral gap exists between the large and small scales.

  3. Validation of the High-Risk Pregnancy Stress Scale in a sample of hospitalized Greek high-risk pregnant women.

    Science.gov (United States)

    Gourounti, Kleanthi; Karpathiotaki, Natassa; Karapanou, Vassiliki; Antzaklis, Panos; Daskalakis, Georgios

    2016-01-01

    The aim of the authors in this study was to determine the psychometric properties of the Greek adaptation of the High-Risk Pregnancy Stress Scale (HRPSS) in a sample of high-risk hospitalized pregnant women. The sample consisted of 133 high-risk pregnant women with gestational age from 9 to 37 weeks. Data were collected between February and June of 2014. HRPSS was "forward-backward" translated from English to Greek. Principal axis factoring with promax rotation was used to test the factor structure of the HRPSS. Measures of state anxiety (STAI) and depressive symptoms (EPDS) were used to assess the convergent validity of the HRPSS. Exploratory factor analysis suggested three factors: concerns of pregnancy, movement restriction, and isolation and restriction of external activities. Construct validity was confirmed by computing correlations between the HRPSS and constructions of anxiety and depressive symptoms. Internal consistency reliability was satisfactory (α = 0.813). The original factor structure of the HRPSS was only partly replicated. The results of the exploratory factor analysis suggested that a three-factor solution instead of a two-factor solution would be the most adequate. The HRPSS is an appropriate measure for assessing the levels of concerns regarding pregnancy outcome, movement restriction, isolation, and external activity restrictions in Greek high-risk pregnant women.

  4. Evaluation of Psychometric Properties of the Arabic Version of PSS Stress Measuring Scale in the Moroccan Population

    Directory of Open Access Journals (Sweden)

    Dalal Ben Loubir

    2014-12-01

    Full Text Available This study was conducted to examine the psychometric properties of the classic Arabic version of the 10-item Perceived Stress Scale (PSS10 in a large sample of Moroccan population. A cross-sectional survey was yielded between December 2013 and January 2014 following an accidental sampling. Individuals aged above 18, from different socioeconomic categories, were invited to take part in the study. The participants had completed a questionnaire including the classic Arabic versions of PSS10. Two data collection methods involving the paper questionnaire (PQ and an electronic questionnaire (EQ were solicited. The psychometric properties of PSS10 were examined by internal consistency, test–retest reliability, convergent validity, and factorial structure. A total of 1,099 individuals have participated in the study. Internal consistencies of the classic Arabic PSS10 for both of PQ and EQ were respectively α = 0.72 and α = 0.85; the test–retest reliability score was 0.91. In both of PQ and EQ, PSS10 scores were higher among females (p < .01, and were positively and significantly correlated with the DASS21 subscales. The principal component analysis provided a two-factor structure. The percentages of variance explained by the two factors were 55.58 for EQ and 54.61 for PQ. The classic Arabic version of the PSS10 showed satisfactory psychometric properties in both data collection methods.

  5. Validation of a Chinese version of the stress overload scale-short and its use as a screening tool for mental health status.

    Science.gov (United States)

    Duan, Wenjie; Mu, Wenlong

    2017-10-19

    Although stress emerges when environmental demands exceed personal resources, existing measurement methods for stress focus only on one aspect. The newly-developed Short Stress Overload Scale (SOS-S) assesses the extent of stress by assessing both event load (i.e., environmental demands) and personal vulnerability (i.e., personal resources). The present study was designed to evaluate the psychometric properties of the Chinese version of Stress Overload Scale-Short (SOS-SC), and further examine its roles in screening mental health status. A total of 1364 participants were recruited from communities and colleges for scale validation. Reliabilities were good throughout the subsamples (ω > 0.80). Confirmatory factor analysis indicated the acceptable goodness-of-fit for the two-factor correlated model (Sample 1: 560 community residents). Multi-group confirmatory factor analysis confirmed measurement invariance across community residents (Sample 1) and college students (Sample 2 and Sample 3). Criterion validity and convergent validity were established (Sample 2: 554 college students). Latent moderated structural equations demonstrated that the relationship between SOS-SC and depression is moderated by social support (Sample 2), further validating the SOS-SC. In addition, the SOS-SC effectively screened individuals in a population at different levels of mental health status (i.e., "at risk" vs. "at low risk" for depression symptoms and/or wellbeing). The SOS-SC exhibits acceptable psychometric properties in the Chinese context. That said, the two aspects of stress can be differentiated by the Chinese context, therefore, the SOS-SC can be used to measure stress and screen mental health status among the Chinese population, and monitor and evaluate health-promoting interventions.

  6. Sensitivity of the scale partition for variational multiscale large-eddy simulation of channel flow

    OpenAIRE

    Holmen, J; Hughes, T.J.R; Oberai, A.A.; Wells, G. N.

    2004-01-01

    The variational multiscale method has been shown to perform well for large-eddy simulation (LES) of turbulent flows. The method relies upon a partition of the resolved velocity field into large- and small-scale components. The subgrid model then acts only on the small scales of motion, unlike conventional LES models which act on all scales of motion. For homogeneous isotropic turbulence and turbulent channel flows, the multiscale model can outperform conventional LES formulations. An issue in...

  7. USING CMAQ FOR EXPOSURE MODELING AND CHARACTERIZING THE SUB-GRID VARIABILITY FOR EXPOSURE ESTIMATES

    Science.gov (United States)

    Atmospheric processes and the associated transport and dispersion of atmospheric pollutants are known to be highly variable in time and space. Current air quality models that characterize atmospheric chemistry effects, e.g. the Community Multi-scale Air Quality (CMAQ), provide vo...

  8. A New Approach to Validate Subgrid Models in Complex High Reynolds Number Flows

    Science.gov (United States)

    1994-05-01

    data are also shown. These figures show the characteristic decrease in correla- tion when the grid is coarsened with the scale similarity model showing...passmms sogbe .iului by a Pus* dll- apWaishmalm ass" immp to bpssm do af sepia abdas h bell pufai aftg a pmiuayomd NO P) emd a smA amedidg of do @*M

  9. Physics and dynamics coupling across scales in the next generation CESM: Meeting the challenge of high resolution. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Vincent E.

    2015-02-21

    This is a final report for a SciDAC grant supported by BER. The project implemented a novel technique for coupling small-scale dynamics and microphysics into a community climate model. The technique uses subcolumns that are sampled in Monte Carlo fashion from a distribution of subgrid variability. The resulting global simulations show several improvements over the status quo.

  10. Numerical Methods for the Optimization of Nonlinear Residual-Based Sungrid-Scale Models Using the Variational Germano Identity

    NARCIS (Netherlands)

    Maher, G.D.; Hulshoff, S.J.

    2014-01-01

    The Variational Germano Identity [1, 2] is used to optimize the coefficients of residual-based subgrid-scale models that arise from the application of a Variational Multiscale Method [3, 4]. It is demonstrated that numerical iterative methods can be used to solve the Germano relations to obtain

  11. Comparison of contact stresses of the test tyres used by the one third scale model mobile load simulator (MMLS3) and the full-scale test tyres of the Heavy Vehicle Simulator (HVS) - a summary

    CSIR Research Space (South Africa)

    De Beer, Morris

    2007-07-01

    Full Text Available for the different test tyres was selected for the comparison. This parameter, referred to as the Maximum Vertical Contact Stress (MVCS) indicated, on average, that it increased linearly with tyre inflation pressure for both types of the 1/3rd scale MMLS3 test... devices reported higher vertical contact stresses at the upper level of tyre inflation pressures. It is therefore recommended that the influence of test surface characteristics and the impact on SIM measurements of HVS and MMLS3 tyres be investigated...

  12. Model Validation for Propulsion - On the TFNS and LES Subgrid Models for a Bluff Body Stabilized Flame

    Science.gov (United States)

    Wey, Thomas

    2017-01-01

    With advances in computational power and availability of distributed computers, the use of even the most complex of turbulent chemical interaction models in combustors and coupled analysis of combustors and turbines is now possible and more and more affordable for realistic geometries. Recent more stringent emission standards have enticed the development of more fuel-efficient and low-emission combustion system for aircraft gas turbine applications. It is known that the NOx emissions tend to increase dramatically with increasing flame temperature. It is well known that the major difficulty, when modeling the turbulence-chemistry interaction, lies in the high non-linearity of the reaction rate expressed in terms of the temperature and species mass fractions. The transport filtered density function (FDF) model and the linear eddy model (LEM), which both use local instantaneous values of the temperature and mass fractions, have been shown to often provide more accurate results of turbulent combustion. In the present, the time-filtered Navier-Stokes (TFNS) approach capable of capturing unsteady flow structures important for turbulent mixing in the combustion chamber and two different subgrid models, LEM-like and EUPDF-like, capable of emulating the major processes occurring in the turbulence-chemistry interaction will be used to perform reacting flow simulations of a selected test case. The selected test case from the Volvo Validation Rig was documented by Sjunnesson.

  13. [A new scale for measuring the psycho-physical effects of work-related stress in a perspective of methods integration].

    Science.gov (United States)

    Falco, Alessandra; Girardi, D; Dal Corso, Laura; De Carlo, N A; Sarto, F; Marcuzzo, G; Vianello, L; Magosso, D; Bartolucci, G B

    2012-01-01

    This study fits into a perspective of integrated work-related stress assessment, in response to the need to limit the common method variance and the role played by individual variables in subjective measures. The goal of this study was to check the metric properties of a new scale of mental and physical strain developed for the evaluation of stress symptoms by the physician and to detect the antecedents of psycho-physical symptoms, in terms of both individual and work characteristics, through an integrated approach. The study was conducted on 409 workers involved in health surveillance activities, to whom the new scale and a subjective assessment tool were administered. Confirmatory factor analysis showed that the scale is a reliable tool for hetero-evaluation of psycho-physical symptoms attributable to stress at work. Moreover, specific individual characteristics, such as the presence of prior health disorders and the female gender, and organizational features, such as the pathological work/life conflict and the workload, were found to be risk factors in relation to psychological and physical strain. Age, consumption of alcoholic beverages between meals, relationships with colleagues, and the characteristics of the workplace were instead found to be important protective factors. The adoption of an integrated approach made it possible to improve and study in depth the ways of work-related stress assessment, highlighting the pivotal role of the occupational health physician making the evaluation.

  14. Residual stress determination in oxide layers at different length scales combining Raman spectroscopy and X-ray diffraction: Application to chromia-forming metallic alloys

    Science.gov (United States)

    Guerain, Mathieu; Grosseau-Poussard, Jean-Luc; Geandier, Guillaume; Panicaud, Benoit; Tamura, Nobumichi; Kunz, Martin; Dejoie, Catherine; Micha, Jean-Sebastien; Thiaudière, Dominique; Goudeau, Philippe

    2017-11-01

    In oxidizing environments, the protection of metals and alloys against further oxidation at high temperature is provided by the oxide film itself. This protection is efficient only if the formed film adheres well to the metal (substrate), i.e., without microcracks and spalls induced by thermomechanical stresses. In this study, the residual stresses at both macroscopic and microscopic scales in the oxide film adhering to the substrate and over the damaged areas have been rigorously determined on the same samples for both techniques. Ni-30Cr and Fe-47Cr alloys have been oxidized together at 900 and 1000 °C, respectively, to create films with a thickness of a few microns. A multi-scale approach was adopted: macroscopic stress was determined by conventional X-ray diffraction and Raman spectroscopy, while microscopic residual stress mappings were performed over different types of bucklings using Raman micro-spectroscopy and synchrotron micro-diffraction. A very good agreement is found at macro- and microscales between the residual stress values obtained with both techniques, giving confidence on the reliability of the measurements. In addition, relevant structural information at the interface between the metallic substrate and the oxide layer was collected by micro-diffraction, a non-destructive technique that allows mapping through the oxide layer, and both the grain size and the crystallographic orientation of the supporting polycrystalline metal located either under a buckling or not were measured.

  15. Positive childhood experiences predict less psychopathology and stress in pregnant women with childhood adversity: A pilot study of the benevolent childhood experiences (BCEs) scale.

    Science.gov (United States)

    Narayan, Angela J; Rivera, Luisa M; Bernstein, Rosemary E; Harris, William W; Lieberman, Alicia F

    2017-10-06

    This pilot study examined the psychometric properties of the Benevolent Childhood Experiences (BCEs) scale, a new instrument designed to assess positive early life experiences in adults with histories of childhood maltreatment and other adversities. A counterpart to the Adverse Childhood Experiences (ACEs) questionnaire, the BCEs was developed to be multiculturally-sensitive and applicable regardless of socioeconomic position, urban-rural background, or immigration status. Higher levels of BCEs were hypothesized to predict lower levels of psychopathology and stress beyond the effects of ACES in a sample of ethnically diverse, low-income pregnant women. BCEs were also expected to show adequate internal validity across racial/ethnic groups and test-retest stability from the prenatal to the postnatal period. Participants were 101 pregnant women (M=29.10years, SD=6.56, range=18-44; 37% Latina, 22% African-American, 20% White, 21% biracial/multiracial/other; 37% foreign-born, 26% Spanish-speaking) who completed the BCEs and ACEs scales; assessments of prenatal depression and post-traumatic stress disorder (PTSD) symptoms, perceived stress, and exposure to stressful life events (SLEs) during pregnancy; and demographic information. Higher levels of BCEs predicted less PTSD symptoms and SLEs, above and beyond ACEs. The BCEs showed excellent test-retest reliability, and mean levels were comparable across racial/ethnic and Spanish-English groups of women. Person-oriented analyses also showed that higher levels of BCEs offset the effects of ACEs on prenatal stress and psychopathology. The BCEs scale indexes promising promotive factors associated with lower trauma-related symptomatology and stress exposure during pregnancy and illuminates how favorable childhood experiences may counteract long-term effects of childhood adversity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT) Method.

    Science.gov (United States)

    Qian, Cheng; Fan, Jiajie; Fang, Jiayi; Yu, Chaohua; Ren, Yi; Fan, Xuejun; Zhang, Guoqi

    2017-10-16

    By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED) products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT) in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs), i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively), were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample's rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs) of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT) depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs.

  17. Experimental determination of the micro-scale strength and stress-strain relation of an epoxy resin

    DEFF Research Database (Denmark)

    Zike, Sanita; Sørensen, Bent F.; Mikkelsen, Lars Pilgaard

    2016-01-01

    An approach is developed for determining the stress-strain law and a failure stress appropriate for micro-mechanical models of polymer materials. Double cantilever beam test specimens, made of an epoxy polymer with notches having finite root radius, were subjected to pure bending moments in an en......An approach is developed for determining the stress-strain law and a failure stress appropriate for micro-mechanical models of polymer materials. Double cantilever beam test specimens, made of an epoxy polymer with notches having finite root radius, were subjected to pure bending moments...

  18. Why PUB needs scaling

    Science.gov (United States)

    Lovejoy, S.; Schertzer, D.; Hubert, P.; Mouchel, J. M.; Benjoudhi, H.; Tchigurinskaya, Y.; Gaume, E.; Vesseire, J.-M.

    2003-04-01

    Hydrological fields display an extreme variability over a wide range of space-time scales. This variability is beyond the scope of classical mathematical and modeling methods which are forced to combine homogeneity assumptions with scale truncations and subgrid parameterizations. These ad hoc procedures nevertheless lead to complex numerical codes: they are difficult to transfer from one basin to another one, or even to verify with data at a different scale. Tuning the model parameters is hazardous: “predictions” are often reduced to fitting existing observations and are in any case essentially limited to the narrow range of space-time scales over which the parameters have been estimated. In contrast, in recent scaling approaches heterogeneity and uncertainty at all scales are no longer obstacles. The variability is viewed as a consequence of a scale symmetry which must first be elucidated and then exploited: small scale homogeneity assumptions are replaced by small scale heterogeneity assumptions which are verified from data covering wide ranges of scale. PUB provides an unprecedented opportunity not only to test scaling concepts and techniques, but also to development them further. Indeed, PUB can be restated in the following manner: given a partial knowledge on the input (atmospheric states, dynamics and fluxes) and of the media (basin) over a given range of scales, what can we predict for the output (steamflow and water quality) and over which range of scales? We illustrate this state of the art with examples taken from various projects involving precipitation and stream flow collectively spanning the range of scales from centimeters to planetary scales in space, from seconds to tens of years in time.

  19. Evaluation of Flow-Induced Dynamic Stress and Vibration of Volute Casing for a Large-Scale Double-Suction Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Fu-Jun Wang

    2013-01-01

    Full Text Available The transient analysis was carried out to investigate the dynamic stress and vibration of volute casing for a large double-suction centrifugal pump by using the transient fluid-structure interaction theory. The flow pulsations at flow rate ranging from 60% to 100% of the nominal flow rate (Qd were taken as the boundary conditions for FEM analysis of the pump volute casing structure. The results revealed that, for all operating conditions, the maximum stress located at the volute tongue region, whereas the maximum vibration displacement happened close to the shaft hole region. It was also found that the blade passing frequency and its harmonics were dominant in the variations of dynamic stress and vibration displacement. The amplitude of the dominant frequency for the maximum stress detected at 0.6 Qd was 1.14 times that at Qd, lower than the related difference observed for pressure fluctuations (3.23 times. This study provides an effective method to quantify the flow-induced structural dynamic characteristics for a large-scale double-suction pump. It can be used to direct the hydraulic and structural design and stable operation, as well as fatigue life prediction for large-scale pumps.

  20. Photometric and Colorimetric Assessment of LED Chip Scale Packages by Using a Step-Stress Accelerated Degradation Test (SSADT Method

    Directory of Open Access Journals (Sweden)

    Cheng Qian

    2017-10-01

    Full Text Available By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs, i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively, were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample’s rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs.

  1. Large scale finite element solvers for the large eddy simulation of incompressible turbulent flows

    OpenAIRE

    Colomés Gené, Oriol

    2016-01-01

    In this thesis we have developed a path towards large scale Finite Element simulations of turbulent incompressible flows. We have assessed the performance of residual-based variational multiscale (VMS) methods for the large eddy simulation (LES) of turbulent incompressible flows. We consider VMS models obtained by different subgrid scale approximations which include either static or dynamic subscales, linear or nonlinear multiscale splitting, and different choices of the subscale space. W...

  2. Factor structure of the Perceived Stress Scale-10 (PSS) across English and Spanish language responders in the HCHS/SOL Sociocultural Ancillary Study.

    Science.gov (United States)

    Perera, Marisa J; Brintz, Carrie E; Birnbaum-Weitzman, Orit; Penedo, Frank J; Gallo, Linda C; Gonzalez, Patricia; Gouskova, Natalia; Isasi, Carmen R; Navas-Nacher, Elena L; Perreira, Krista M; Roesch, Scott C; Schneiderman, Neil; Llabre, Maria M

    2017-03-01

    Despite widespread use, psychometric investigation of the original English and translated Spanish versions of the 10-item Perceived Stress Scale (PSS; Cohen, Kamarck, & Mermelstein, 1983) has been limited among the U.S. Hispanic/Latino population. The present study examined the factor structure, factorial invariance, and reliability and validity of PSS scores from English and Spanish versions using data from 5,176 Hispanics/Latinos who participated in the Hispanic Community Health Study/Study of Latinos Sociocultural Ancillary Study. The total sample and language multigroup confirmatory factor analyses supported a bifactor model with all 10 PSS items loading on a general perceived stress factor, and the 4 reverse-worded items also loading on a reverse-worded factor. Internal consistency ranged from .68 to .78, and it was indicated that reliable variance exists beyond the general perceived stress factor. The model displayed configural, metric, scalar, and residual invariance across language groups. Convergent validity analyses indicated that both the general perceived stress factor and the reverse-worded factor were related to scores of depression, anxiety, and anger in the expected directions. The reverse-worded factor added to the validity of the PSS beyond the general perceived stress factor. The total computed score of the PSS can be recommended for use with Hispanics/Latinos in the United States that complete the measure in English or Spanish and the reverse-worded factor can enhance prediction. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  3. Transcript profiling of salinity stress responses by large-scale expressed sequence tag analysis in Mesembryanthemum crystallinum.

    Science.gov (United States)

    Kore-eda, Shin; Cushman, Mary Ann; Akselrod, Inna; Bufford, Davina; Fredrickson, Monica; Clark, Elizabeth; Cushman, John C

    2004-10-27

    The common ice plant, Mesembryanthemum crystallinum, is a halophytic (salt-loving) member of the Aizoaceae, which switches from C3 photosynthesis to Crassulacean acid metabolism (CAM) when exposed to salinity or water-deficit stress. CAM is a metabolic adaptation of photosynthetic carbon fixation that improves water use efficiency by shifting net CO2 uptake to the night, thereby reducing transpirational water loss. To improve our understanding of the molecular genetic underpinnings and control mechanisms for Crassulacean acid metabolism (CAM) and other salinity stress response adaptations, a total of 9733 expressed sequence tags (ESTs) from cDNAs derived from leaf tissues of well-watered and salinity-stressed (0.5 M NaCl for 30 and 48 h) were characterized. Clustering and assembly of these ESTs resulted in the identification of a total of 3676 tentative unique gene sequences (1249 tentative consensus sequences and 2427 singleton ESTs) expressed in leaves of ice plant under unstressed and salinity stressed conditions. The same number (2782) of ESTs from each library (total=8346 ESTs) were randomly selected and analyzed to compare expression profiles among the control and salt stressed leaf tissues. EST frequencies for transcripts encoding CAM-related enzymes, pathogenesis-related, senescence-associated, cell death-related, and stress-related proteins such as heat shock proteins (HSPs), chaperones, early light-inducible proteins, ion homeostasis, antioxidative stress, detoxification, and biosynthetic enzymes for osmoprotectants increased 2-12-fold in cDNA libraries constructed from salt stressed plants. In contrast, the frequency of ESTs encoding light-harvesting and photosystem complexes and C3 photosynthetic enzymes decreased 4-fold overall following salinity stress with transcripts for ribulose bisphosphate carboxylase/oxygenase (RuBisCO) subunits decreasing 7-fold. Moreover, stressed plants contained a higher percentage of ESTs encoding novel and/or functionally

  4. Comparative genome-scale analysis of niche-based stress-responsive genes in Lactobacillus helveticus strains.

    Science.gov (United States)

    Senan, Suja; Prajapati, Jashbhai B; Joshi, Chaitanya G

    2014-04-01

    Next generation sequencing technologies with advanced bioinformatic tools present a unique opportunity to compare genomes from diverse niches. The identification of niche-specific stress-responsive genes can help in characterizing robust strains for multiple applications. In this study, we attempted to compare the stress-responsive genes of a potential probiotic strain, Lactobacillus helveticus MTCC 5463, and a cheese starter strain, Lactobacillus helveticus DPC 4571, from a gut and dairy niche, respectively. Sequencing of MTCC 5463 was done using 454 GS FLX, and contigs were assembled using GS Assembler software. Genome analysis was done using BLAST hits and the prokaryotic annotation server RAST. The MTCC 5463 genome carried multiple orthologs of genes governing stress responses, whereas the DPC 4571 genome lacked in the number of major stress-response proteins. The absence of the bile salt hydrolase gene in DPC 4571 and its presence in MTCC 5463 clearly indicated niche adaptation. Further, MTCC 5463 carried higher copy numbers of genes contributing towards heat, cold, osmotic, and oxidative stress resistance as compared with DPC 4571. Through comparative genomics, we could thus identify stress-responsive gene sets required to adapt to gut and dairy niches.

  5. Application of a Multi-Scale form of Terzaghi’s Effective Stress Principle for Unsaturated Expansive Clays to Simulate Hydro-Mechanical Behavior During Hydration

    Directory of Open Access Journals (Sweden)

    Mainka Julia

    2016-01-01

    Full Text Available Our recently developed multi-scale form of Terzaghi’s effective stress principle for unsaturated swelling clays that was rigorously derived by periodic homogenization starting from micro- and nano-mechanical analyses is applied to numerically simulate one-dimensional swelling pressure tests of compacted bentonites during hydration. The total macroscopic stress captures the coupling between disjoining forces at the nanoscopic scale of clay platelets and capillary effects at the microscopic scale of clay aggregates over the entire water content range. The numerical results allow to draw conclusions on the water transfer mechanism between inter- and intra-aggregate pores during hydration and consequently on the evolution of the external swelling pressure resulting from the competition between capillary and disjoining forces. In addition, such application highlights the abilities and the limits of the electrical double-layer theory to compute the disjoining pressure in the nano-pores. For large platelet distances, in the range of osmotic swelling, the nature of the disjoining pressure is electro-chemical and can be computed from Poisson-Boltzmann theory. Conversely, at small distances, in the crystalline swelling, a solvation component has to be added to account for the molecular nature of the solvent. As a first improvement of the nano-scale description the solvent is treated as a hard sphere fluid using Density Functional Theory.

  6. Trehalose as a stress marker of the physiological impact of mixing on yeast production: scale-down reactors and mini-bioreactors investigations

    Directory of Open Access Journals (Sweden)

    Thonart, P.

    2010-01-01

    Full Text Available Trehalose is a reserve carbohydrate produced by Saccharomyces cerevisiae under stress conditions and used as a cryoprotectant during freeze drying. So the cellular content of trehalose is an important parameter to control in industrial context. Scale-down reactors have been used to produce Saccharomyces cerevisiae. These reactors permit to mimic the hydrodynamic conditions experienced by cells during large scale production. Three types of scale-down reactors have been tested, differing by the geometry of the non-mixed part and the recirculation flow rate. The results show that cells cultivated in scale-down reactors produced less trehalose compared to the reference reactor. These results are completed by the study of the expression of the TPS2 promoter coupled with a green fluorescent protein (GFP. TPS2 is a gene coding for a subunit of the enzymatic complex responsible of trehalose synthesis. This strain was produced in mini-bioreactors which are shake flasks equipped with a dissolved oxygen probe. This approach allows using trehalose, or related enzymes, as a cellular marker of the stress encountered by yeast in industrial process.

  7. Application of a single root-scale model to improve macroscopic modeling of root water uptake: focus on osmotic stress

    Science.gov (United States)

    Jorda, Helena; Perelman, Adi; Lazarovitch, Naftali; Vanderborght, Jan

    2017-04-01

    Root water uptake is a fundamental process in the hydrological cycle and it largely regulates the water balance in the soil vadose zone. Macroscopic stress functions are currently used to estimate the effect of salinity on root water uptake. These functions commonly assume stress to be a function of bulk salinity and of the plant sensitivity to osmotic stress expressed as the salinity at which transpiration is reduced by half or so called tolerance value. However, they fail to integrate additional relevant factors such as atmospheric conditions or root architectural traits. We conducted a comprehensive simulation study on a single root using a 3-D physically-based model that resolves flow and transport to individual root segments and that couples flow in the soil and root system. The effect of salt concentrations on root water uptake was accounted for by including osmotic water potential gradients between the solution at the soil root interface and the root xylem sap in the hydraulic gradient between the soil and root. A large set of factors were studied, namely, potential transpiration rate and dynamics, root length density (RLD), irrigation water quality and irrigation frequency, and leaching fraction. Results were fitted to the macroscopic function developed by van Genuchten and Hoffman (1984) and the dependency of osmotic stress and the fitted macroscopic parameters on the studied factors was evaluated. Osmotic stress was found to be highly dependent on RLD. Low RLDs result in a larger stress to the plant due to high evaporative demand per root length unit. In addition, osmotic stress was positively correlated to potential transpiration rate, and sinusoidal potential transpiration lead to larger stress than when imposed as a constant boundary condition. Macroscopic parameters are usually computed as single values for each crop and used for the entire growing season. However, our study shows that both tolerance value and shape parameter p from the van Genuchten

  8. Psychometric properties of the Resilience Scale for Adults (RSA) and its relationship with life-stress, anxiety and depression in a Hispanic Latin-American community sample.

    Science.gov (United States)

    Morote, Roxanna; Hjemdal, Odin; Martinez Uribe, Patricia; Corveleyn, Jozef

    2017-01-01

    Resilience is a multi-dimensional construct associated with health and well-being. At present, we do not yet have a valid, scientific instrument that is designed to evaluate adult resilience in Spanish-speaking countries and that accounts for family, social and individual components. This study aimed at investigating the construct and cross-cultural validity of the Resilience Scale for Adults (RSA) by combining Confirmatory Factor Analysis (CFA), Multidimensional Scaling (MDS) and Hierarchical Regression models in a Hispanic Latin-American group. A community sample of 805 adults answered the RSA, Spanish Language Stressful Life-Events checklist (SL-SLE), and the Hopkins Symptom Checklist-25 (HSCL-25). First-order CFA verified the six factors structure for the RSA (RMSEA = .037, SRMR = .047, CFI = .91, TLI = .90). Five RSA scales and total score have good internal consistency (scales α > .70; total score α = .90). Two second-order CFA verified the intrapersonal and interpersonal dimensions of the protector factors of resilience, as well as their commonality and uniqueness with affective symptoms (anxiety and depression). An exploratory MDS reproduced the relations of RSA items and factors at first and second-order levels against random simulated data, thereby providing initial evidence of its cross-cultural validity in a Spanish-speaking group. The Four-steps hierarchical model showed that the RSA scales are the strongest predictors of anxiety and depression-greater than gender, age, education and stressful life-events. Three RSA scales are significant unique predictors of affective symptoms. In addition, similar to findings in diverse cultural settings, resilience is positively associated with age but not with education. Women report higher scores of Social Resources and Social Competence and lower scores of Perception of the Self. In conclusion, this study demonstrates the construct and criterion-related validity of the RSA in broad, diverse and Spanish speaking

  9. A Multi-scale Refined Zigzag Theory for Multilayered Composite and Sandwich Plates with Improved Transverse Shear Stresses

    Science.gov (United States)

    Iurlaro, Luigi; Gherlone, Marco; Di Sciuva, Marco; Tessler, Alexander

    2013-01-01

    The Refined Zigzag Theory (RZT) enables accurate predictions of the in-plane displacements, strains, and stresses. The transverse shear stresses obtained from constitutive equations are layer-wise constant. Although these transverse shear stresses are generally accurate in the average, layer-wise sense, they are nevertheless discontinuous at layer interfaces, and thus they violate the requisite interlaminar continuity of transverse stresses. Recently, Tessler applied Reissner's mixed variational theorem and RZT kinematic assumptions to derive an accurate and efficient shear-deformation theory for homogeneous, laminated composite, and sandwich beams, called RZT(m), where "m" stands for "mixed". Herein, the RZT(m) for beams is extended to plate analysis, where two alternative assumptions for the transverse shear stresses field are examined: the first follows Tessler's formulation, whereas the second is based on Murakami's polynomial approach. Results for elasto-static simply supported and cantilever plates demonstrate that Tessler's formulation results in a powerful and efficient structural theory that is well-suited for the analysis of multilayered composite and sandwich panels.

  10. An ultra scale-down characterization of low shear stress primary recovery stages to enhance selectivity of fusion protein recovery from its molecular variants.

    Science.gov (United States)

    Lau, Eduardo C; Kong, Simyee; McNulty, Shaun; Entwisle, Claire; McIlgorm, Ann; Dalton, Kate A; Hoare, Mike

    2013-07-01

    Fusion proteins offer the prospect of new therapeutic products with multiple functions. The primary recovery is investigated of a fusion protein consisting of modified E2 protein from hepatitis C virus fused to human IgG1 Fc and expressed in a Chinese hamster ovary (CHO) cell line. Fusion protein products inevitably pose increased challenge in preparation and purification. Of particular concerns are: (i) the impact of shear stress on product integrity and (ii) the presence of product-related contaminants which could prove challenging to remove during the high resolution purification steps. This paper addresses the use of microwell-based ultra scale-down (USD) methods to develop a bioprocess strategy focused on the integration of cell culture and cell removal operations and where the focus is on the use of operations which impart low shear stress levels even when applied at eventual manufacturing scale. An USD shear device was used to demonstrate that cells exposed to high process stresses such as those that occur in the feed zone of a continuous non-hermetic centrifuge resulted in the reduction of the fusion protein and also the release of glycosylated intracellular variants. In addition, extended cell culture resulted in release of such variants. USD mimics of low shear stress, hydrohermetic feed zone centrifugation and of depth filtration were used to demonstrate little to no release during recovery of these variants with both results verified at pilot scale. Furthermore, the USD studies were used to predict removal of contaminants such as lipids, nucleic acids, and cell debris with, for example, depth filtration delivering greater removal than for centrifugation but a small (~10%) decrease in yield of the fusion protein. These USD observations of product recovery and carryover of contaminants were also confirmed at pilot scale as was also the capacity or throughput achievable for continuous centrifugation or for depth filtration. The advantages are discussed of

  11. Construct validity of the parent-child sleep interactions scale (PSIS): associations with parenting, family stress, and maternal and child psychopathology.

    Science.gov (United States)

    Smith, Victoria C; Leppert, Katherine A; Alfano, Candice A; Dougherty, Lea R

    2014-08-01

    Using a multi-method design, this study examined the construct validity of the Parent-Child Sleep Interactions Scale (PSIS; Alfano et al., 2013), which measures sleep-related parenting behaviors and interactions that contribute to preschoolers' sleep problems. Participants included a community sample of 155 preschoolers (ages 3-5years; 51.6% female). Primary caregivers completed the PSIS. Parenting styles and behaviors were assessed with laboratory observations and parent reports. Parent and child psychopathology and family life stress were assessed with clinical interviews and parent reports. Bivariate correlations revealed significant associations between the PSIS and a number of variables, including lower observed parental support and quality of instruction; higher observed parental intrusiveness; authoritative, authoritarian, and permissive parenting styles; current maternal depressive and/or anxiety disorders and depressive symptomatology; increased stressful life events; lower marital satisfaction; and higher child depressive, anxiety, attention-deficit/hyperactivity disorder (ADHD), and oppositional defiant disorder (ODD) symptoms. The patterns of association varied based on the specific PSIS scale. The PSIS demonstrates meaningful associations with parenting, maternal psychopathology, family stress, and child psychopathology and functioning. Findings suggest that the PSIS is a valid measure for assessing sleep-related parent/child behaviors and interactions among preschoolers, suited to real-world settings. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. The responsiveness of the International Prostate Symptom Score, Incontinence Impact Questionnaire-7 and Depression, Anxiety and Stress Scale-21 in patients with lower urinary tract symptoms.

    Science.gov (United States)

    Choi, Edmond P H; Chin, Weng Yee; Lam, Cindy L K; Wan, Eric Y F

    2015-08-01

    To examine the responsiveness of a combined symptom severity and health-related quality of life measure, condition-specific health-related quality of life measure and mental health measure in patients with lower urinary tract symptoms. To establish the responsiveness of measures that accurately capture the change in health status of patients is crucial before any longitudinal studies can be appropriately planned and evaluated. Prospective longitudinal observational study. 402 patients were surveyed at baseline and 1-year using the International Prostate Symptom Score, the Incontinence Impact Questionnaire-7 and Depression, Anxiety and Stress Scales-21. The internal and external responsiveness were assessed. Surveys were conducted from March 2013-July 2014. In participants with improvements, the internal responsiveness for detecting positive changes was satisfactory in males and females for all scales, expect for the Depression subscale. The health-related quality of life question of the International Prostate Symptom Score was more externally responsive than the Incontinence Impact Questionnaire-7. The International Prostate Symptom Score and Anxiety and Stress subscales were more responsive in males than in females. The symptom questions of the International Prostate Symptom Score and Anxiety and Stress subscales were not externally responsive in females. The health-related quality of life question of the International Prostate Symptom Score outperformed the Incontinence Impact Questionnaire-7 in both males and females, in terms of external responsiveness. © 2015 John Wiley & Sons Ltd.

  13. Linking flux network measurements to continental scale simulations: ecosystem carbon dioxide exchange capacity under non-water-stressed conditions

    NARCIS (Netherlands)

    Owen, K.E.; Tenhunen, J.; Reichstein, M.; Wang, Q.; Falge, E.; Geyer, R.; Xiao, X.; Stoy, P.; Ammann, C.; Arain, A.; Aubinet, M.; Aurela, M.; Bernhofer, C.; Chojnicki, B.H.; Granier, A.; Gruenwald, T.; Hadley, J.; Heinesch, B.; Hollinger, D.; Knohl, A.; Kutsch, W.; Lohila, A.; Meyers, T.; Moors, E.J.; Moureaux, C.; Pilegaard, K.; Saigusa, N.; Verma, S.; Vesala, T.; Vogel, C.

    2007-01-01

    This paper examines long-term eddy covariance data from 18 European and 17 North American and Asian forest, wetland, tundra, grassland, and cropland sites under non-water-stressed conditions with an empirical rectangular hyperbolic light response model and a single layer two light-class

  14. Frost stress evolution and winter pea ideotype in the context of climate warming at a regional scale

    Directory of Open Access Journals (Sweden)

    Castel Thierry

    2017-01-01

    Full Text Available Pea (Pisum sativum L. is an important crop in temperate regions for its high seed protein concentration that is particularly sensitive to abiotic stresses. The abrupt temperature increase known as the “1987/1988 temperature regime shift” that occurs over Europe is questioning how winter pea will perform in the changing climate. This study assessed the winter frost damage evolution along from 1961 to 2015 in Burgundy-Franche-Comté by using: (1 daily observed and gridded regional temperature data and (2 a validated crop winter frost stress model calibrated for pea. This study shows a global decrease of the frost stress nevertheless resulting from a subtle balance between the decrease in its intensity and the increase of the number of events. The frost stress evolution patterns with warming depend on both plant frost resistance level and acclimation rate and are still sensitive to winter climate fluctuations. This study provides relevant information for breeding performant winter crop ideotypes able to moderate detrimental effects of climate change and offering new cropping opportunities in temperate regions.

  15. Contribution to viscosity from the structural relaxation via the atomic scale Green-Kubo stress correlation function.

    Science.gov (United States)

    Levashov, V A

    2017-11-14

    We studied the connection between the structural relaxation and viscosity for a binary model of repulsive particles in the supercooled liquid regime. The used approach is based on the decomposition of the macroscopic Green-Kubo stress correlation function into the correlation functions between the atomic level stresses. Previously we used the approach to study an iron-like single component system of particles. The role of vibrational motion has been addressed through the demonstration of the relationship between viscosity and the shear waves propagating over large distances. In our previous considerations, however, we did not discuss the role of the structural relaxation. Here we suggest that the contribution to viscosity from the structural relaxation can be taken into account through the consideration of the contribution from the atomic stress auto-correlation term only. This conclusion, however, does not mean that only the auto-correlation term represents the contribution to viscosity from the structural relaxation. Previously the role of the structural relaxation for viscosity has been addressed through the considerations of the transitions between inherent structures and within the mode-coupling theory by other authors. In the present work, we study the structural relaxation through the considerations of the parent liquid and the atomic level stress correlations in it. The comparison with the results obtained on the inherent structures also is made. Our current results suggest, as our previous observations, that in the supercooled liquid regime, the vibrational contribution to viscosity extends over the times that are much larger than the Einstein's vibrational period and much larger than the times that it takes for the shear waves to propagate over the model systems. Besides addressing the atomic level shear stress correlations, we also studied correlations between the atomic level pressure elements.

  16. Contribution to viscosity from the structural relaxation via the atomic scale Green-Kubo stress correlation function

    Science.gov (United States)

    Levashov, V. A.

    2017-11-01

    We studied the connection between the structural relaxation and viscosity for a binary model of repulsive particles in the supercooled liquid regime. The used approach is based on the decomposition of the macroscopic Green-Kubo stress correlation function into the correlation functions between the atomic level stresses. Previously we used the approach to study an iron-like single component system of particles. The role of vibrational motion has been addressed through the demonstration of the relationship between viscosity and the shear waves propagating over large distances. In our previous considerations, however, we did not discuss the role of the structural relaxation. Here we suggest that the contribution to viscosity from the structural relaxation can be taken into account through the consideration of the contribution from the atomic stress auto-correlation term only. This conclusion, however, does not mean that only the auto-correlation term represents the contribution to viscosity from the structural relaxation. Previously the role of the structural relaxation for viscosity has been addressed through the considerations of the transitions between inherent structures and within the mode-coupling theory by other authors. In the present work, we study the structural relaxation through the considerations of the parent liquid and the atomic level stress correlations in it. The comparison with the results obtained on the inherent structures also is made. Our current results suggest, as our previous observations, that in the supercooled liquid regime, the vibrational contribution to viscosity extends over the times that are much larger than the Einstein's vibrational period and much larger than the times that it takes for the shear waves to propagate over the model systems. Besides addressing the atomic level shear stress correlations, we also studied correlations between the atomic level pressure elements.

  17. A self-rating scale for the assessment of posttraumatic stress disorder in Dutch Resistance veterans of World War II.

    Science.gov (United States)

    Hovens, J E; Falger, P R; Op den Velde, W; Meijer, P; de Groen, J H; van Duijn, H

    1993-03-01

    The present study reports on the development of a Dutch PTSD scale based on the DSM-III criteria for PTSD. Test-retest reliability was .91. The scale showed an internal consistency with a coefficient alpha of .88. Factor analysis on a large sample of Resistance veterans (N = 967) yielded six factors, which represent intrusive thoughts, physiological reactions, detachment, rage, active confrontation, and guilt.

  18. Olive Plantation Mapping on a Sub-Tree Scale with Object-Based Image Analysis of Multispectral UAV Data; Operational Potential in Tree Stress Monitoring

    Directory of Open Access Journals (Sweden)

    Christos Karydas

    2017-12-01

    Full Text Available The objective of this study was to develop a methodology for mapping olive plantations on a sub-tree scale. For this purpose, multispectral imagery of an almost 60-ha plantation in Greece was acquired with an Unmanned Aerial Vehicle. Objects smaller than the tree crown were produced with image segmentation. Three image features were indicated as optimum for discriminating olive trees from other objects in the plantation, in a rule-based classification algorithm. After limited manual corrections, the final output was validated by an overall accuracy of 93%. The overall processing chain can be considered as suitable for operational olive tree monitoring for potential stresses.

  19. Frost stress evolution and winter pea ideotype in the context of climate warming at a regional scale

    OpenAIRE

    Castel Thierry; Lecomte Christophe; Richard Yves; Lejeune-Hénaut Isabelle; Larmure Annabelle

    2017-01-01

    Pea (Pisum sativum L.) is an important crop in temperate regions for its high seed protein concentration that is particularly sensitive to abiotic stresses. The abrupt temperature increase known as the “1987/1988 temperature regime shift” that occurs over Europe is questioning how winter pea will perform in the changing climate. This study assessed the winter frost damage evolution along from 1961 to 2015 in Burgundy-Franche-Comté by using: (1) daily observed and gridded regional temperature ...

  20. Wall shear stress fluctuations: Mixed scaling and their effects on velocity fluctuations in a turbulent boundary layer

    Science.gov (United States)

    Diaz-Daniel, Carlos; Laizet, Sylvain; Vassilicos, J. Christos

    2017-05-01

    The present work investigates numerically the statistics of the wall shear stress fluctuations in a turbulent boundary layer (TBL) and their relation to the velocity fluctuations outside of the near-wall region. The flow data are obtained from a Direct Numerical Simulation (DNS) of a zero pressure-gradient TBL using the high-order flow solver Incompact3D [S. Laizet and E. Lamballais, "High-order compact schemes for incompressible flows: A simple and efficient method with quasi-spectral accuracy," J. Comput. Phys. 228(16), 5989 (2009)]. The maximum Reynolds number of the simulation is R e𝜃≈2000 , based on the free-stream velocity and the momentum thickness of the boundary layer. The simulation data suggest that the root-mean-squared fluctuations of the streamwise and spanwise wall shear-stress components τx and τz follow a logarithmic dependence on the Reynolds number, consistent with the empirical correlation of Örlü and Schlatter [R. Örlü and P. Schlatter, "On the fluctuating wall-shear stress in zero pressure-gradient turbulent boundary layer flows," Phys. Fluids 23, 021704 (2011)]. These functional dependencies can be used to estimate the Reynolds number dependence of the wall turbulence dissipation rate in good agreement with reference DNS data. Our results suggest that the rare negative events of τx can be associated with the extreme values of τz and are related to the presence of coherent structures in the buffer layer, mainly quasi-streamwise vortices. We also develop a theoretical model, based on a generalisation of the Townsend-Perry hypothesis of wall-attached eddies, to link the statistical moments of the filtered wall shear stress fluctuations and the second order structure function of fluctuating velocities at a distance y from the wall. This model suggests that the wall shear stress fluctuations may induce a higher slope in the turbulence energy spectra of streamwise velocities than the one predicted by the Townsend-Perry attached

  1. The relationship between temperament, job stress and overcommitment: a cross-sectional study using the TEMPS-A and a scale of ERI.

    Science.gov (United States)

    Tei-Tominaga, Maki; Akiyama, Tsuyoshi; Miyake, Yuko; Sakai, Yoshie

    2009-10-01

    This cross-sectional study examined the relationship between temperament, job stress, and overcommitment using the Temperament Evaluation of Memphis, Pisa, Paris and San Diego-Autoquestionnaire version (TEMPS-A) and a scale of the effort-reward imbalance (ERI) model. In July 2004, self-administered questionnaires were distributed to all employees in a Japanese IT service company through the company postal system. Total response rate was 63% (N=874), with 730 completed questionnaires. Information collected included individual attributes, employment and organizational characteristics. The TEMPS-A and the Japanese version of the ERI questionnaire were self-administered. The completed data of 637 personal computer technical support staff (87%) were used in a hierarchical regression analysis. Our results showed that depressive and anxious temperaments attenuate the influence of working hours and influence effort and rewards independently. While actual working hours had more impact on perceived high effort, our findings regarding rewards suggest that understanding anxious and depressive temperaments has a significant role in stress self-management. Temperaments explained 36% of the variance of overcommitment, and the variance was more than that of mean working hours. Our research has provided meaningful insights into occupational health, which could assist employees in self-management of job stress and contribute to better adaptation at the workplace.

  2. The piezoelectronic stress transduction switch for very large-scale integration, low voltage sensor computation, and radio frequency applications

    Science.gov (United States)

    Magdǎu, I.-B.; Liu, X.-H.; Kuroda, M. A.; Shaw, T. M.; Crain, J.; Solomon, P. M.; Newns, D. M.; Martyna, G. J.

    2015-08-01

    The piezoelectronic transduction switch is a device with potential as a post-CMOS transistor due to its predicted multi-GHz, low voltage performance on the VLSI-scale. However, the operating principle of the switch has wider applicability. We use theory and simulation to optimize the device across a wide range of length scales and application spaces and to understand the physics underlying its behavior. We show that the four-terminal VLSI-scale switch can operate at a line voltage of 115 mV while as a low voltage-large area device, ≈200 mV operation at clock speeds of ≈2 GHz can be achieved with a desirable 104 On/Off ratio—ideal for on-board computing in sensors. At yet larger scales, the device is predicted to operate as a fast (≈250 ps) radio frequency (RF) switch exhibiting high cyclability, low On resistance and low Off capacitance, resulting in a robust switch with a RF figure of merit of ≈4 fs. These performance benchmarks cannot be approached with CMOS which has reached fundamental limits. In detail, a combination of finite element modeling and ab initio calculations enables prediction of switching voltages for a given design. A multivariate search method then establishes a set of physics-based design rules, discovering the key factors for each application. The results demonstrate that the piezoelectronic transduction switch can offer fast, low power applications spanning several domains of the information technology infrastructure.

  3. Association of Stressful Life Events with Psychological Problems: A Large-Scale Community-Based Study Using Grouped Outcomes Latent Factor Regression with Latent Predictors

    Directory of Open Access Journals (Sweden)

    Akbar Hassanzadeh

    2017-01-01

    Full Text Available Objective. The current study is aimed at investigating the association between stressful life events and psychological problems in a large sample of Iranian adults. Method. In a cross-sectional large-scale community-based study, 4763 Iranian adults, living in Isfahan, Iran, were investigated. Grouped outcomes latent factor regression on latent predictors was used for modeling the association of psychological problems (depression, anxiety, and psychological distress, measured by Hospital Anxiety and Depression Scale (HADS and General Health Questionnaire (GHQ-12, as the grouped outcomes, and stressful life events, measured by a self-administered stressful life events (SLEs questionnaire, as the latent predictors. Results. The results showed that the personal stressors domain has significant positive association with psychological distress (β=0.19, anxiety (β=0.25, depression (β=0.15, and their collective profile score (β=0.20, with greater associations in females (β=0.28 than in males (β=0.13 (all P<0.001. In addition, in the adjusted models, the regression coefficients for the association of social stressors domain and psychological problems profile score were 0.37, 0.35, and 0.46 in total sample, males, and females, respectively (P<0.001. Conclusion. Results of our study indicated that different stressors, particularly those socioeconomic related, have an effective impact on psychological problems. It is important to consider the social and cultural background of a population for managing the stressors as an effective approach for preventing and reducing the destructive burden of psychological problems.

  4. Scaling for stress similarity and distorted-shape similarity in bending and torsion under maximal muscle forces concurs with geometric similarity among different-sized animals.

    Science.gov (United States)

    Norberg, R Ake; Aldrin, Björn S Wetterholm

    2010-08-15

    When geometric similarity, or isometry, prevails among animals of different sizes their form and proportions are similar. Weight increases as the cube of the length dimension, while cross-sectional areas increase as its square, so in load-bearing structural elements the stress, caused by the body weight, increases in direct proportion to the length dimension, both for pure axial loads and for transverse bending and torsional loads. On this account, large body sizes would be expected to set up compensatory selection on the proportions of supporting structures, making them disproportionately thicker as required to maintain similar, size-independent safety factors against breakage. Most previous scaling theories have assumed that the strength of support elements has evolved with respect to loads due to the body weight. But then, from the arguments above, a scaling principle different from the geometric similarity rule would be required in order for safety factors to remain similar among different-sized animals. Still, most comparable animals of 'similar kind' scale in accordance with the geometric similarity rule. Here, we instead argue that muscle forces cause much larger loads on structural support elements during maximum performance events (such as during prey capture or escape from predators) than do loads dictated by the body weight (such as during cruising locomotion), and that structural strength therefore might evolve with respect to maximal muscle forces rather than to the body weight. We explore how the transverse and longitudinal lengths of structural support elements must scale to one another, and to muscle transverse length, in order to satisfy each of the following, functionally based, similarity principles for support elements placed in bending, or in torsion, by maximal muscle forces during locomotion: (1) similarity in axial stress, or (2) in torsional shear stress, and (3) similarity in bent shape, or (4) in twisted shape. A dimensional relationship

  5. States of stress and slip partitioning in a continental scale strike-slip duplex: Tectonic and magmatic implications by means of finite element modeling

    Science.gov (United States)

    Iturrieta, Pablo Cristián; Hurtado, Daniel E.; Cembrano, José; Stanton-Yonge, Ashley

    2017-09-01

    Orogenic belts at oblique convergent subduction margins accommodate deformation in several trench-parallel domains, one of which is the magmatic arc, commonly regarded as taking up the margin-parallel, strike-slip component. However, the stress state and kinematics of volcanic arcs is more complex than usually recognized, involving first- and second-order faults with distinctive slip senses and mutual interaction. These are usually organized into regional scale strike-slip duplexes, associated with both long-term and short-term heterogeneous deformation and magmatic activity. This is the case of the 1100 km-long Liquiñe-Ofqui Fault System in the Southern Andes, made up of two overlapping margin-parallel master faults joined by several NE-striking second-order faults. We present a finite element model addressing the nature and spatial distribution of stress across and along the volcanic arc in the Southern Andes to understand slip partitioning and the connection between tectonics and magmatism, particularly during the interseismic phase of the subduction earthquake cycle. We correlate the dynamics of the strike-slip duplex with geological, seismic and magma transport evidence documented by previous work, showing consistency between the model and the inferred fault system behavior. Our results show that maximum principal stress orientations are heterogeneously distributed within the continental margin, ranging from 15° to 25° counter-clockwise (with respect to the convergence vector) in the master faults and 10-19° clockwise in the forearc and backarc domains. We calculate the stress tensor ellipticity, indicating simple shearing in the eastern master fault and transpressional stress in the western master fault. Subsidiary faults undergo transtensional-to-extensional stress states. The eastern master fault displays slip rates of 5 to 10 mm/yr, whereas the western and subsidiary faults show slips rates of 1 to 5 mm/yr. Our results endorse that favorably oriented

  6. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale

    OpenAIRE

    Hossain, R.; Pahlevani, F.; Quadir, M. Z.; Sahajwalla, V.

    2016-01-01

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels? performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a com...

  7. A sub-grid, mixture-fraction-based thermodynamic equilibrium model for gas phase combustion in FIRETEC: development and results

    Science.gov (United States)

    M. M. Clark; T. H. Fletcher; R. R. Linn

    2010-01-01

    The chemical processes of gas phase combustion in wildland fires are complex and occur at length-scales that are not resolved in computational fluid dynamics (CFD) models of landscape-scale wildland fire. A new approach for modelling fire chemistry in HIGRAD/FIRETEC (a landscape-scale CFD wildfire model) applies a mixture– fraction model relying on thermodynamic...

  8. The Ability of Recovery Locus of Control Scale (RLOC) and Post-traumatic Stress Symptoms (PTSS) to Predict the Physical Functioning of Stroke Patients.

    Science.gov (United States)

    Mohd Zulkifly, Mohd Faizal; Ghazali, Shazli Ezzat; Che Din, Normah; Desa, Asmawati; Raymond, Azman Ali

    2015-09-01

    The aim of this study was to address the ability of the recovery locus of control scale (RLOC) and post-traumatic stress symptoms (PTSS) to predict physical functioning among stroke patients. In addition, the best predictors within the subdomains of the RLOC and PTSS were also investigated. A total of 147 stroke patients aged 33-85 years who had intact cognitive functioning were involved in the study. The Recovery Locus of Control Scale (RLOC), the Impact of Event Scale-Revised (IES-R), and the Barthel Index (ADL) were administered to respondents six weeks after stroke. The results showed that the RLOC and PTSS were significant predictors and were capable of predicting 31% of the physical functioning of stroke patients (adjusted R2 = 0.31; P < 0.001). Furthermore, with respect to clinical factors, the affected lesion side contributed to predicting 7% of the physical functioning (R2= 0.07; P < 0.001). A hierarchical regression analysis found that the internal recovery locus of control (IRLOC) was a predictor capable of explaining 18% of the predicted physical functioning (adjusted R2= 0.18; P < 0.001). Meanwhile, avoidance was the most influential significant predictor among PTSS, contributing to 24% of the predicting physical functioning (adjusted R2= 0.24; P < 0.001). In conclusion, the RLOC and PTSS were capable of predicting physical functioning among stroke patients.

  9. Log-layer mismatch and modeling of the fluctuating wall stress in wall-modeled large-eddy simulations

    Science.gov (United States)

    Yang, Xiang I. A.; Park, George Ilhwan; Moin, Parviz

    2017-10-01

    Log-layer mismatch refers to a chronic problem found in wall-modeled large-eddy simulation (WMLES) or detached-eddy simulation, where the modeled wall-shear stress deviates from the true one by approximately 15 % . Many efforts have been made to resolve this mismatch. The often-used fixes, which are generally ad hoc, include modifying subgrid-scale stress models, adding a stochastic forcing, and moving the LES-wall-model matching location away from the wall. An analysis motivated by the integral wall-model formalism suggests that log-layer mismatch is resolved by the built-in physics-based temporal filtering. In this work we investigate in detail the effects of local filtering on log-layer mismatch. We show that both local temporal filtering and local wall-parallel filtering resolve log-layer mismatch without moving the LES-wall-model matching location away from the wall. Additionally, we look into the momentum balance in the near-wall region to provide an alternative explanation of how LLM occurs, which does not necessarily rely on the numerical-error argument. While filtering resolves log-layer mismatch, the quality of the wall-shear stress fluctuations predicted by WMLES does not improve with our remedy. The wall-shear stress fluctuations are highly underpredicted due to the implied use of LES filtering. However, good agreement can be found when the WMLES data are compared to the direct numerical simulation data filtered at the corresponding WMLES resolutions.

  10. The Bosnian version of the international self-report measure of posttraumatic stress disorder, the Posttraumatic Stress Diagnostic Scale, is reliable and valid in a variety of different adult samples affected by war

    Directory of Open Access Journals (Sweden)

    Rosner Rita

    2005-02-01

    Full Text Available Abstract Background The aim of the present study was to assess the internal consistency and discriminant and convergent validity of the Bosnian version of a self-report measure of posttraumatic stress disorder (PTSD, the Posttraumatic Stress Diagnostic Scale (PTDS. The PTDS yields both a PTSD diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV and a measure of symptom severity. Methods 812 people living in Sarajevo or in Banja Luka in Bosnia-Herzegovina, of whom the majority had experienced a high number of traumatic war events, were administered the PTDS and other measures of trauma-related psychopathology. The psychometric properties of the instrument were assessed using Cronbach's alpha and principal components analysis, and its construct validity was assessed via Spearman correlation coefficients with the other instruments. Results The PTDS and its subscales demonstrated high internal consistency. The principal components revealed by an exploratory analysis are broadly consistent with the DSM-IV subscales except that they reproduce some previously reported difficulties with the "numbing" items from the avoidance subscale. The construct validity of the PTDS was supported by appropriate correlations with other relevant measures of trauma related psychopathology. Conclusion The Bosnian version of the PTDS thus appears to be a time-economic and psychometrically sound measure for screening and assessing current PTSD. This self-report measure awaits further validation by interview methods.

  11. Reducing residual stresses and deformations in selective laser melting through multi-level multi-scale optimization of cellular scanning strategy

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Hattel, Jesper Henri

    2016-01-01

    Residual stresses and deformations continue to remain one of the primary challenges towards expanding the scope of selective laser melting as an industrial scale manufacturing process. While process monitoring and feedback-based process control of the process has shown significant potential...... are compared with standard scanning strategies and have been used to manufacture standard samples. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only......., there is still dearth of techniques to tackle the issue. Numerical modelling of selective laser melting process has thus been an active area of research in the last few years. However, large computational resource requirements have slowed the usage of these models for optimizing the process.In this paper...

  12. Farmland productivity under stress conditions: a field scale monitoring and modeling study on the Venice coastland, Italy

    Science.gov (United States)

    Manoli, Gabriele; Scudiero, Elia; Putti, Mario; Morari, Francesco; Teatini, Pietro

    2014-05-01

    The Venice coastland, Italy, is a precarious environment jeopardized by both natural and anthropogenic factors. Due to a land elevation below sea level and the presence of sandy paleo-channels, salinization of soil and shallow groundwater is posing a serious threat to the agricultural productivity of the region. In order to identify and quantify the impacts of the saltwater contamination on crop productivity an integrated monitoring and modeling approach is used. A representative 21 ha basin cultivated with maize crop has been extensively studied by soil sampling, geophysical surveys, continuous hydrological monitoring and crop yield distribution. Based on field observations a field-scale model of soil moisture dynamics coupled with plant transpiration, photosynthesis and growth has been developed and applied at the site.

  13. A large-scale fumigation system for investigating interactions between air pollution and cold stress on plants.

    Science.gov (United States)

    Lucas, P W; Cottam, D A; Mansfield, T A

    1987-01-01

    A new large-scale closed chamber fumigation system with cooling facilities is described for studying effects of low concentrations of SO(2), NO(2) and O(3) and low temperatures on woody species and herbaceous plants. The system is based on modified hemispherical greenhouses with a forced air ventilation system. This provides a chamber environment with low spatial variability of pollutant gas concentrations and rapid air circulation which allows exposure of plants at near ambient temperatures and relative humidity. Large capacity cooling units come into operation when ambient temperatures fall below 0 degrees C, and these allow chamber temperatures to be lowered by an additional 4 to 8 degrees C in experiments designed to test whether exposure to pollutants enhances the frost sensitivity of plants.

  14. Monitoring African savanna water use and water stress from local to regional scale: supporting rangeland management (pilot experience in Kruger National Park, South Africa).

    Science.gov (United States)

    Andreu, Ana; Dube, Timothy; Nieto, Hector; González-Dugo, Maria P.; Hülsmann, Stephan

    2017-04-01

    Drought periods and erratic rainfall patterns across large parts of Africa result in water-limited environments like savannas, highly sensitive to land management practices and changes in climate. Over the Southern part of the continent, savannas are key productive landscapes supporting livestock, crops and rural livelihoods. Monitoring water use and the natural vegetation stress over these semi-arid complex ecosystems can support rangeland management, to maintain long-term productivity. However, the precision/resolution/accuracy of the information required for management will differ at each scale: farm-local (e.g. evaluating the effect of management practices, livestock densities, crop production and grazing), to watershed (e.g. evaluating the effect of fire, detection of vulnerable areas) and regional (e.g. early prediction of drought). To overcome these constrains, TIGER project 401 combines two approaches that take advantage of different conceptual and operational capabilities of Earth Observation data sources. Sentinel 2 high spatial (10 m) and temporal ( 5 days) resolution VIS/NIR images are used for a continuous monitoring of vegetation cover and unstressed evapotranspiration (ET - using Kc-FAO56 method). This methodology will provide the required resolution for farm-local scales, tracking separately the seasonal variations of each canopy layer growth (grass and trees). Meanwhile, lower spatial resolution (1 km) MODIS thermal data allow to determine a regional water stress index (ratio between actual ET, estimated using Two Source Energy Balance-TSEB, and potential ET), supporting the detection of vulnerable areas. The model framework was tested and validated over savanna-type experimental areas (Skukuza & Malopeni), and later applied over the whole Kruger National Park during 2015-2016.

  15. Effect of an antioxidant functional food beverage on exercise-induced oxidative stress: a long-term and large-scale clinical intervention study.

    Science.gov (United States)

    Muñoz, Maria E; Galan, Ana I; Palacios, Encarna; Diez, Maria A; Muguerza, Begoña; Cobaleda, Cesar; Calvo, Jose I; Aruoma, Okezie I; Sanchez-Garcia, Isidro; Jimenez, Rafael

    2010-11-28

    The efficacy of long-term intake of a novel functional food supplement Funciona™ containing vitamins and juiced fruits was evaluated in order to assess the net effect of physical activity and antioxidant potentials in healthy older adult population. The long-term (2 years) and large-scale (400 older adult subjects) interventional study was based on both moderate-intensity exercise practice and concurrent supplementation. Sustained exercise-induced oxidative stress as reflected in significantly increased blood thiobarbituric acid-reactive substances (TBARS) (+15%), protein carbonyl groups (PC) (+18%) and oxidized glutathione (GSSG) (+112%) concentrations, and leukocyte 8-OHdG contents (23%). Exercise decreased the reduced/oxidized glutathione (GSH/GSSG) molar ratio (-43%) and plasma vitamin C levels (-22%). Supplementation with Funciona™ was significant in preventing oxidative damage to lipid, protein and DNA, and normalizing blood GSSG, GSH/GSSG and vitamin C levels. Thus daily intake of the antioxidant functional beverage counteracts the exercise-induced oxidative stress in free-living older subjects, and might be necessary to restore impaired antioxidant balance due long-term regular exercise. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

  16. Sub-Grid-Scale Description of Turbulent Magnetic Reconnection in Magnetohydrodynamics

    CERN Document Server

    Widmer, Fabien; Yokoi, Nobumitsu

    2015-01-01

    Magnetic reconnection requires, at least locally, a non-ideal plasma response. In collisionless space and astrophysical plasmas, turbulence could permit this instead of the too rare binary collisions. We investigated the influence of turbulence on the reconnection rate in the framework of a single fluid compressible MHD approach. The goal is to find out, whether unresolved, sub-grid for MHD simulations, turbulence can enhance the reconnection process in high Reynolds number astrophysical plasma. We solve, simultaneously with the grid-scale MHD equations, evolution equations for the sub-grid turbulent energy and cross helicity according to Yokoi's model (Yokoi (2013)) where turbulence is self-generated and -sustained through the inhomogeneities of the mean fields. Simulations of Harris and force free sheets confirm the results of Higashimori et al. (2013) and new results are obtained about the dependence on resistivity for large Reynolds number as well as guide field effects. The amount of energy transferred f...

  17. Effect of aerosol subgrid variability on aerosol optical depth and cloud condensation nuclei: Implications for global aerosol modelling

    NARCIS (Netherlands)

    Weigum, Natalie; Schutgens, Nick; Stier, Philip

    2016-01-01

    A fundamental limitation of grid-based models is their inability to resolve variability on scales smaller than a grid box. Past research has shown that significant aerosol variability exists on scales smaller than these grid-boxes, which can lead to discrepancies in simulated aerosol climate effects

  18. Adaptação cultural e validação para a língua portuguesa da Parental Stress Scale: Neonatal Intensive Care Unit (PSS:NICU Adaptación cultural y validación al idioma português del Parental Stress Scale: Neonatal Intensive Care Unit (PSS:NICU Cultural adaptation and validation for the portuguese language of the Parental Stress Scale: Neonatal Intensive Care Unit (PSS:NICU

    Directory of Open Access Journals (Sweden)

    Sandra Regina de Souza

    2012-01-01

    Full Text Available OBJETIVO: Traduzir, realizar a adaptação cultural e validar a escala Parental Stress Scale:Neonatal Intensive Care Unit (PSS:NICU para a língua portuguesa. MÉTODOS: Utilizou-se o método descritivo de validação de instrumentos de medida, baseado nas etapas propostas por Guillemin et al. A análise da confiabilidade foi realizada por meio dos testes e retestes e da consistência interna. Na validação clínica, participaram 163 pais de recém-nascidos internados em Unidade de Terapia Intensiva Neonatal (UTIN. RESULTADOS: Os coeficientes de correlação intraclasse ficaram em torno de 0,70 mostrando boa estabilidade entre as duas avaliações. A análise fatorial pelo método de componentes principais utilizou os mesmos critérios da escala original, com rotação Varimax, com grau de variância adequado de 57,9%. Os maiores níveis de estresse dos pais foram obtidos na subescala "alteração do papel de pais". CONCLUSÃO: A PSS:NICU na versão em português é uma ferramenta válida e confiável para avaliação do estresse de pais com filho internado na UTIN.OBJETIVO: Traducir, realizar la adaptación cultural y validar la escala Parental Stress Scale:Neonatal Intensive Care Unit (PSS:NICU al idioma portugués. MÉTODOS: Se utilizó el método descriptivo de validación de instrumentos de medida, basado en las etapas propuestas por Guillemin et al. El análisis de la confiabilidad fue realizado por medio de los tests y retests y de la consistencia interna. En la validación clínica, participaron 163 padres de recién nacidos internados en una Unidad de Cuidados Intensivos Neonatal (UCIN. RESULTADOS: Los coeficientes de correlación intraclase quedaron alrededor de 0,70 mostrando buena estabilidad entre las dos evaluaciones El análisis factorial por el método de componentes principales utilizó los mismos criterios de la escala original, con rotación Varimax, con grado de varianza adecuado de 57,9%. Los mayores niveles de estrés de

  19. Validation of the 10-item Chinese perceived stress scale in elderly service workers: one-factor versus two-factor structure.

    Science.gov (United States)

    Ng, Siu-Man

    2013-01-01

    Despite its popularity, the psychometric properties of the 10-item Chinese Perceived Stress Scale (CPSS-10) in working adults are yet to be evaluated. This study examined CPSS-10 in elderly service workers through a questionnaire survey. The sample was randomly split into two for exploratory (EFA) and confirmatory factor analysis (CFA). A high response rate (93%) was achieved, resulting in 992 completed questionnaires. EFA with the first split sample favored a two-factor over a one-factor solution. The second factor had eigenvalue 2.00 and provided 19.95% explained variance. In CFA with the second split sample, the two-factor structure showed satisfactory goodness-of-fit (CFI = 0.93, RMSEA = 0.06) while the one-factor structure showed poor data fit (CFI = 0.62, RMSEA = 0.14). Further analyses on the two-factor structure revealed that the whole scale and two subscales had acceptable internal consistency (Cronbach's alphas = 0.67 to 0.78). The total score was positively associated with perceived workload and burnout (r = 0.17 to 0.48), but negatively with work engagement (r = -0.13 to -0.30). In contrary to previous studies, a low inter-factor correlation (r = -0.08) was revealed. CPSS-10 showed a stable two-factor structure with satisfactory internal consistency and construct validity.

  20. Collaborative Project: High-resolution Global Modeling of the Effects of Subgrid-Scale Clouds and Turbulence on Precipitating Cloud Systems

    Energy Technology Data Exchange (ETDEWEB)

    Randall, David A. [Colorado State Univ., Fort Collins, CO (United States). Dept. of Atmospheric Science

    2015-11-01

    We proposed to implement, test, and evaluate recently developed turbulence parameterizations, using a wide variety of methods and modeling frameworks together with observations including ARM data. We have successfully tested three different turbulence parameterizations in versions of the Community Atmosphere Model: CLUBB, SHOC, and IPHOC. All three produce significant improvements in the simulated climate. CLUBB will be used in CAM6, and also in ACME. SHOC is being tested in the NCEP forecast model. In addition, we have achieved a better understanding of the strengths and limitations of the PDF-based parameterizations of turbulence and convection.

  1. Evaluation of the Transport and Diffusion of Pollutants over an Urban Area Using a Local-Scale Advection-Diffusion Model and a Sub-Grid Street Model

    DEFF Research Database (Denmark)

    Salerno, R.; Vignati, E.

    1994-01-01

    Fifth International Conference on the Development and Application of Computer Techniques to Environmental Studies, Envirosoft/94.......Fifth International Conference on the Development and Application of Computer Techniques to Environmental Studies, Envirosoft/94....

  2. Final Technical Report for "High-resolution global modeling of the effects of subgrid-scale clouds and turbulence on precipitating cloud systems"

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Vincent [Univ. of Wisconsin, Milwaukee, WI (United States)

    2016-11-25

    The Multiscale Modeling Framework (MMF) embeds a cloud-resolving model in each grid column of a General Circulation Model (GCM). A MMF model does not need to use a deep convective parameterization, and thereby dispenses with the uncertainties in such parameterizations. However, MMF models grossly under-resolve shallow boundary-layer clouds, and hence those clouds may still benefit from parameterization. In this grant, we successfully created a climate model that embeds a cloud parameterization (“CLUBB”) within a MMF model. This involved interfacing CLUBB’s clouds with microphysics and reducing computational cost. We have evaluated the resulting simulated clouds and precipitation with satellite observations. The chief benefit of the project is to provide a MMF model that has an improved representation of clouds and that provides improved simulations of precipitation.

  3. Evaluation of LES models for flow over bluff body from engineering ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Results are also discussed keeping in view limitations of LES methodology of modelling for practical problems and current developments. It is concluded that a one-equation model for subgrid kinetic energy is the best choice. Keywords. Subgrid scale stress models; engineering flows; flow over bluff body. 1. Introduction.

  4. Large-scale proteomic analysis of the grapevine leaf apoplastic fluid reveals mainly stress-related proteins and cell wall modifying enzymes.

    Science.gov (United States)

    Delaunois, Bertrand; Colby, Thomas; Belloy, Nicolas; Conreux, Alexandra; Harzen, Anne; Baillieul, Fabienne; Clément, Christophe; Schmidt, Jürgen; Jeandet, Philippe; Cordelier, Sylvain

    2013-02-08

    The extracellular space or apoplast forms a path through the whole plant and acts as an interface with the environment. The apoplast is composed of plant cell wall and space within which apoplastic fluid provides a means of delivering molecules and facilitates intercellular communications. However, the apoplastic fluid extraction from in planta systems remains challenging and this is particularly true for grapevine (Vitis vinifera L.), a worldwide-cultivated fruit plant. Large-scale proteomic analysis reveals the protein content of the grapevine leaf apoplastic fluid and the free interactive proteome map considerably facilitates the study of the grapevine proteome. To obtain a snapshot of the grapevine apoplastic fluid proteome, a vacuum-infiltration-centrifugation method was optimized to collect the apoplastic fluid from non-challenged grapevine leaves. Soluble apoplastic protein patterns were then compared to whole leaf soluble protein profiles by 2D-PAGE analyses. Subsequent MALDI-TOF/TOF mass spectrometry of tryptically digested protein spots was used to identify proteins. This large-scale proteomic analysis established a well-defined proteomic map of whole leaf and leaf apoplastic soluble proteins, with 223 and 177 analyzed spots, respectively. All data arising from proteomic, MS and MS/MS analyses were deposited in the public database world-2DPAGE. Prediction tools revealed a high proportion of (i) classical secreted proteins but also of non-classical secreted proteins namely Leaderless Secreted Proteins (LSPs) in the apoplastic protein content and (ii) proteins potentially involved in stress reactions and/or in cell wall metabolism. This approach provides free online interactive reference maps annotating a large number of soluble proteins of the whole leaf and the apoplastic fluid of grapevine leaf. To our knowledge, this is the first detailed proteome study of grapevine apoplastic fluid providing a comprehensive overview of the most abundant proteins

  5. Identification of tissue-specific, abiotic stress-responsive gene expression patterns in wine grape (Vitis vinifera L. based on curation and mining of large-scale EST data sets

    Directory of Open Access Journals (Sweden)

    Cramer Grant R

    2011-05-01

    Full Text Available Abstract Background Abiotic stresses, such as water deficit and soil salinity, result in changes in physiology, nutrient use, and vegetative growth in vines, and ultimately, yield and flavor in berries of wine grape, Vitis vinifera L. Large-scale expressed sequence tags (ESTs were generated, curated, and analyzed to identify major genetic determinants responsible for stress-adaptive responses. Although roots serve as the first site of perception and/or injury for many types of abiotic stress, EST sequencing in root tissues of wine grape exposed to abiotic stresses has been extremely limited to date. To overcome this limitation, large-scale EST sequencing was conducted from root tissues exposed to multiple abiotic stresses. Results A total of 62,236 expressed sequence tags (ESTs were generated from leaf, berry, and root tissues from vines subjected to abiotic stresses and compared with 32,286 ESTs sequenced from 20 public cDNA libraries. Curation to correct annotation errors, clustering and assembly of the berry and leaf ESTs with currently available V. vinifera full-length transcripts and ESTs yielded a total of 13,278 unique sequences, with 2302 singletons and 10,976 mapped to V. vinifera gene models. Of these, 739 transcripts were found to have significant differential expression in stressed leaves and berries including 250 genes not described previously as being abiotic stress responsive. In a second analysis of 16,452 ESTs from a normalized root cDNA library derived from roots exposed to multiple, short-term, abiotic stresses, 135 genes with root-enriched expression patterns were identified on the basis of their relative EST abundance in roots relative to other tissues. Conclusions The large-scale analysis of relative EST frequency counts among a diverse collection of 23 different cDNA libraries from leaf, berry, and root tissues of wine grape exposed to a variety of abiotic stress conditions revealed distinct, tissue-specific expression

  6. Identification of tissue-specific, abiotic stress-responsive gene expression patterns in wine grape (Vitis vinifera L.) based on curation and mining of large-scale EST data sets

    Science.gov (United States)

    2011-01-01

    Background Abiotic stresses, such as water deficit and soil salinity, result in changes in physiology, nutrient use, and vegetative growth in vines, and ultimately, yield and flavor in berries of wine grape, Vitis vinifera L. Large-scale expressed sequence tags (ESTs) were generated, curated, and analyzed to identify major genetic determinants responsible for stress-adaptive responses. Although roots serve as the first site of perception and/or injury for many types of abiotic stress, EST sequencing in root tissues of wine grape exposed to abiotic stresses has been extremely limited to date. To overcome this limitation, large-scale EST sequencing was conducted from root tissues exposed to multiple abiotic stresses. Results A total of 62,236 expressed sequence tags (ESTs) were generated from leaf, berry, and root tissues from vines subjected to abiotic stresses and compared with 32,286 ESTs sequenced from 20 public cDNA libraries. Curation to correct annotation errors, clustering and assembly of the berry and leaf ESTs with currently available V. vinifera full-length transcripts and ESTs yielded a total of 13,278 unique sequences, with 2302 singletons and 10,976 mapped to V. vinifera gene models. Of these, 739 transcripts were found to have significant differential expression in stressed leaves and berries including 250 genes not described previously as being abiotic stress responsive. In a second analysis of 16,452 ESTs from a normalized root cDNA library derived from roots exposed to multiple, short-term, abiotic stresses, 135 genes with root-enriched expression patterns were identified on the basis of their relative EST abundance in roots relative to other tissues. Conclusions The large-scale analysis of relative EST frequency counts among a diverse collection of 23 different cDNA libraries from leaf, berry, and root tissues of wine grape exposed to a variety of abiotic stress conditions revealed distinct, tissue-specific expression patterns, previously

  7. Full-scale 3-D finite element modeling of a two-loop pressurized water reactor for heat transfer, thermal–mechanical cyclic stress analysis, and environmental fatigue life estimation

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish, E-mail: smohanty@anl.gov; Soppet, William K.; Majumdar, Saurindranath; Natesan, Krishnamurti

    2015-12-15

    Highlights: • Full-scale 3-D finite element model. • Pressurized water reactor. • Heat transfer analysis. • Thermal–mechanical stress analysis. • Environmental fatigue life estimation. - Abstract: This paper discusses a system-level finite element model of a two-loop pressurized water reactor (PWR). Based on this model, system-level heat transfer analysis and subsequent sequentially coupled thermal–mechanical stress analysis were performed for typical thermal–mechanical fatigue cycles. The in-air fatigue lives of example components, such as the hot and cold legs, were estimated on the basis of stress analysis results, ASME in-air fatigue life estimation criteria, and fatigue design curves. Furthermore, environmental correction factors and associated PWR environment fatigue lives for the hot and cold legs were estimated by using estimated stress and strain histories and the approach described in US-NRC report: NUREG-6909.

  8. Mechanical behavior of concrete and related porous materials under partial saturation: The effective stress and the viscous softening due to movement of nanometer-scale pore fluid

    Science.gov (United States)

    Vlahinic, Ivan

    It has been said that porous materials are like music: the gaps are as important as the filled-in bits. In other words, in addition to the solid structure, pore characteristics such as size and morphology play a crucial role in defining the overall physical properties of the porous materials. This work goes a step further and examines the behaviors of some porous media that arise when the pore network is occupied by two fluids, principally air and water, as a result of drying or wetting. Such a state gives rise to fluid capillarity which can generate significant negative fluid pressures. In the first part, a constitutive model for drying of an elastic porous medium is proposed and then extended to derive a novel expression for effective stress in partially saturated media. The model is motivated by the fact that in a system that is saturated by two different fluids, two different pressure inherently act on the surfaces of the pore network. This causes a non-uniform strain field in the solid structure, something that is not explicitly accounted for in the classic formulations of this problem. We use some standard micromechanical homogenization techniques to estimate the extent of the 'non-uniformity' and on this basis, evaluate the validity of the classic Bishop effective stress expression for partially saturated materials. In the second part, we examine a diverse class of porous materials which behave in an unexpected (and even counterintuitive) way under the internal moisture fluctuations. In particular, during wetting and drying alike, the solid viscosity of these materials appears to soften, sometimes by an order of magnitude or more. Under load, this can lead to significantly increased rates of deformations. On account of the recent experimental and theoretical findings on the nature of water flow in nanometer-size hydrophillic spaces, we provide a physical explanation for the viscous softening and propose a constitutive law on this basis. To this end, it also

  9. Análise fatorial confirmatória das três versões da Perceived Stress Scale (PSS: um estudo populacional

    Directory of Open Access Journals (Sweden)

    André Faro

    2015-03-01

    Full Text Available Este estudo teve como objetivos realizar a análise fatorial confirmatória da Escala de Estresse Percebido (Perceived Stress Scale- PSS, nas versões traduzidas de 14, 10 e 4 itens; analisar sua validade concorrente com o Questionário de Saúde Geral (QSG-12; mapear o perfil do estresse em uma amostra representativa da população; e estabelecer parâmetros de avaliação do estresse por meio da normatização dos escores da população total. A amostragem foi de base populacional, em formato de conglomerado por setores censitários. Participaram 1.154 habitantes de uma capital do Nordeste brasileiro, sendo a maioria do sexo feminino (55,6%, com nível de escolaridade em ensino médio (51,7%, empregados (72,7% e não tabagistas (90,6%. As medianas de renda e idade ficaram em R$ 1.200,00 e 29 anos. Ao final, constatou-se que houve ajustes satisfatórios para as três versões da PSS apenas em seu modelo bifatorial e a escala com 10 itens se mostrou uma solução harmônica entre as versões completa e mais reduzida, considerando-se a relação entre a parcimônia na quantidade de itens e a robustez estatística deste instrumento. Ademais, a PSS ratificou sua validade concorrente com o QSG-12 e foi feita a normatização dos escores da PSS, estabelecendo-se parâmetros para comparação em futuros estudos.

  10. Modes of Large-Scale Brain Network Organization during Threat Processing and Posttraumatic Stress Disorder Symptom Reduction during TF-CBT among Adolescent Girls.

    Directory of Open Access Journals (Sweden)

    Josh M Cisler

    Full Text Available Posttraumatic stress disorder (PTSD is often chronic and disabling across the lifespan. The gold standard treatment for adolescent PTSD is Trauma-Focused Cognitive-Behavioral Therapy (TF-CBT, though treatment response is variable and mediating neural mechanisms are not well understood. Here, we test whether PTSD symptom reduction during TF-CBT is associated with individual differences in large-scale brain network organization during emotion processing. Twenty adolescent girls, aged 11-16, with PTSD related to assaultive violence completed a 12-session protocol of TF-CBT. Participants completed an emotion processing task, in which neutral and fearful facial expressions were presented either overtly or covertly during 3T fMRI, before and after treatment. Analyses focused on characterizing network properties of modularity, assortativity, and global efficiency within an 824 region-of-interest brain parcellation separately during each of the task blocks using weighted functional connectivity matrices. We similarly analyzed an existing dataset of healthy adolescent girls undergoing an identical emotion processing task to characterize normative network organization. Pre-treatment individual differences in modularity, assortativity, and global efficiency during covert fear vs neutral blocks predicted PTSD symptom reduction. Patients who responded better to treatment had greater network modularity and assortativity but lesser efficiency, a pattern that closely resembled the control participants. At a group level, greater symptom reduction was associated with greater pre-to-post-treatment increases in network assortativity and modularity, but this was more pronounced among participants with less symptom improvement. The results support the hypothesis that modularized and resilient brain organization during emotion processing operate as mechanisms enabling symptom reduction during TF-CBT.

  11. Modes of Large-Scale Brain Network Organization during Threat Processing and Posttraumatic Stress Disorder Symptom Reduction during TF-CBT among Adolescent Girls.

    Science.gov (United States)

    Cisler, Josh M; Sigel, Benjamin A; Kramer, Teresa L; Smitherman, Sonet; Vanderzee, Karin; Pemberton, Joy; Kilts, Clinton D

    2016-01-01

    Posttraumatic stress disorder (PTSD) is often chronic and disabling across the lifespan. The gold standard treatment for adolescent PTSD is Trauma-Focused Cognitive-Behavioral Therapy (TF-CBT), though treatment response is variable and mediating neural mechanisms are not well understood. Here, we test whether PTSD symptom reduction during TF-CBT is associated with individual differences in large-scale brain network organization during emotion processing. Twenty adolescent girls, aged 11-16, with PTSD related to assaultive violence completed a 12-session protocol of TF-CBT. Participants completed an emotion processing task, in which neutral and fearful facial expressions were presented either overtly or covertly during 3T fMRI, before and after treatment. Analyses focused on characterizing network properties of modularity, assortativity, and global efficiency within an 824 region-of-interest brain parcellation separately during each of the task blocks using weighted functional connectivity matrices. We similarly analyzed an existing dataset of healthy adolescent girls undergoing an identical emotion processing task to characterize normative network organization. Pre-treatment individual differences in modularity, assortativity, and global efficiency during covert fear vs neutral blocks predicted PTSD symptom reduction. Patients who responded better to treatment had greater network modularity and assortativity but lesser efficiency, a pattern that closely resembled the control participants. At a group level, greater symptom reduction was associated with greater pre-to-post-treatment increases in network assortativity and modularity, but this was more pronounced among participants with less symptom improvement. The results support the hypothesis that modularized and resilient brain organization during emotion processing operate as mechanisms enabling symptom reduction during TF-CBT.

  12. Imaging stress.

    Science.gov (United States)

    Brielle, Shlomi; Gura, Rotem; Kaganovich, Daniel

    2015-11-01

    Recent innovations in cell biology and imaging approaches are changing the way we study cellular stress, protein misfolding, and aggregation. Studies have begun to show that stress responses are even more variegated and dynamic than previously thought, encompassing nano-scale reorganization of cytosolic machinery that occurs almost instantaneously, much faster than transcriptional responses. Moreover, protein and mRNA quality control is often organized into highly dynamic macromolecular assemblies, or dynamic droplets, which could easily be mistaken for dysfunctional "aggregates," but which are, in fact, regulated functional compartments. The nano-scale architecture of stress-response ranges from diffraction-limited structures like stress granules, P-bodies, and stress foci to slightly larger quality control inclusions like juxta nuclear quality control compartment (JUNQ) and insoluble protein deposit compartment (IPOD), as well as others. Examining the biochemical and physical properties of these dynamic structures necessitates live cell imaging at high spatial and temporal resolution, and techniques to make quantitative measurements with respect to movement, localization, and mobility. Hence, it is important to note some of the most recent observations, while casting an eye towards new imaging approaches that offer the possibility of collecting entirely new kinds of data from living cells.

  13. Evaluation of crack-tip stress fields on microstructural-scale fracture in Al-Al2O3 interpenetrating network composites

    Science.gov (United States)

    Robert J. Moon; Mark Hoffman; Jurgen Rödel; Shigemi Tochino; Giuseppe Pezzotti

    2009-01-01

    The influence of local microstructure on the fracture process at the crack tip in a ceramic–metal composite was assessed by comparing the measured stress at a microstructural level and analogous finite element modelling (FEM). Fluorescence microprobe spectroscopy was used to investigate the influence of near-crack-tip stress fields on the resulting crack propagation at...

  14. The interplay of stressful life events and coping skills on risk for suicidal behavior among youth students in contemporary China: a large scale cross-sectional study

    OpenAIRE

    Tang,Fang; Xue, Fuzhong; Qin, Ping

    2015-01-01

    Background Stressful life events are common among youth students and may induce psychological problems and even suicidal behaviors in those with poor coping skills. This study aims to assess the influence of stressful life events and coping skills on risk for suicidal behavior and to elucidate the underlying mechanism using a large sample of university students in China. Methods 5972 students, randoml...

  15. Grain scale stresses and strains determination by X-ray diffraction; Contribution a l'analyse par diffractometrie X des deformations et des contraintes a l'echelle des grains

    Energy Technology Data Exchange (ETDEWEB)

    Huang, W

    2007-03-15

    A new methodology for strain and stress analysis by X ray diffraction (XRD) in single crystal was developed. It can be applied to determine the second order stress (in grain scale) in single and multi-crystal material with non-cubic lattice. This method is based on the method Ortner I. It has introduced the metric tensor G which is deduced from the lattice space measured by XRD. In the developed method, when the crystal reference is non-orthonormal, an orthonormal reference associated with the crystal basis is defined, so all calculation could be done with usual calculation laws. The use of the least square method allows the acquisition of many more measurements than the six absolute necessary. Then a better metric tensor G is calculated and the statistical error is obtained. This developed method was applied in a bi crystal copper. The experimental results have shown that this method is also effective. The second order residuals stresses for coarse Zn grains in a galvanized coating were determined after annealing. The four coarse grains with different orientations were also characterized and demonstrated the elastic and plastic deformation mechanism in a grain or between the grains during in situ tensile loading. So this method is well able to determine the strains and stresses in grain scale in a mono crystal or multi crystal with any crystalline structure. (author)

  16. Sambandet mellan stress mindset och upplevd stress hos gymnasieungdomar

    OpenAIRE

    Edblad, Patrik

    2016-01-01

    Studien undersökte sambandet mellan stress mindset (individens övertygelser om stress) och upplevd stress hos gymnasieungdomar. 122 deltagare i åldrarna 16-19 år deltog i studien genom att svara på ett elektroniskt formulär. Frågorna bestod av Perceived Stress Scale (PSS-14), som undersökte upplevd stress, och Stress Mindset Measure (SMM), som undersökte deltagarnas mindset om stress. Resultatet visade en signifikant negativ korrelation mellan stress mindset och upplevd stress. Detta gav stöd...

  17. Large scale comparative proteomics of a chloroplast Clp protease mutant reveals folding stress, altered protein homeostasis, and feedback regulation of metabolism.

    Science.gov (United States)

    Zybailov, Boris; Friso, Giulia; Kim, Jitae; Rudella, Andrea; Rodríguez, Verenice Ramírez; Asakura, Yukari; Sun, Qi; van Wijk, Klaas J

    2009-08-01

    The clpr2-1 mutant is delayed in development due to reduction of the chloroplast ClpPR protease complex. To understand the role of Clp proteases in plastid biogenesis and homeostasis, leaf proteomes of young seedlings of clpr2-1 and wild type were compared using large scale mass spectrometry-based quantification using an LTQ-Orbitrap and spectral counting with significance determined by G-tests. Virtually only chloroplast-localized proteins were significantly affected, indicating that the molecular phenotype was confined to the chloroplast. A comparative chloroplast stromal proteome analysis of fully developed plants was used to complement the data set. Chloroplast unfoldase ClpB3 was strongly up-regulated in both young and mature leaves, suggesting widespread and persistent protein folding stress. The importance of ClpB3 in the clp2-1 mutant was demonstrated by the observation that a CLPR2 and CLPB3 double mutant was seedling-lethal. The observed up-regulation of chloroplast chaperones and protein sorting components further illustrated destabilization of protein homeostasis. Delayed rRNA processing and up-regulation of a chloroplast DEAD box RNA helicase and polynucleotide phosphorylase, but no significant change in accumulation of ribosomal subunits, suggested a bottleneck in ribosome assembly or RNA metabolism. Strong up-regulation of a chloroplast translational regulator TypA/BipA GTPase suggested a specific response in plastid gene expression to the distorted homeostasis. The stromal proteases PreP1,2 were up-regulated, likely constituting compensation for reduced Clp protease activity and possibly shared substrates between the ClpP and PreP protease systems. The thylakoid photosynthetic apparatus was decreased in the seedlings, whereas several structural thylakoid-associated plastoglobular proteins were strongly up-regulated. Two thylakoid-associated reductases involved in isoprenoid and chlorophyll synthesis were up-regulated reflecting feedback from rate

  18. Large scale deformation in a locked collisional boundary: Interplay between subsidence and uplift, intraplate stress and inherited lithospheric structure in the late stage of the SE Carpathians evolution.

    NARCIS (Netherlands)

    Matenco, L.C.; Bertotti, G.V.; Leever, K.A.; Cloetingh, S.A.P.L.; Schmid, S.; Tarapoanca, M.; Dinu, C.

    2007-01-01

    The interplay between slab dynamics and intraplate stresses in postcollisional times creates large near-surface deformation, particularly in highly bent orogens with significant lateral variations in mechanical properties. This deformation is expressed through abnormal foredeep geometries and

  19. Psychometric Evaluation of a Six Dimension Scale of Nursing Performance and Student Nurse Stress Index Using an Objective Structured Clinical Examination - Modules for Asthma and Type 1 Diabetes

    National Research Council Canada - National Science Library

    Park, Kyong-ok; Ahn, Young-mee; Kang, Na-rae; Lee, Mi-jin; Sohn, Min

    2013-01-01

    ...) and Student Nurse Stress Index (SNSI) and psychometric evaluation of the two measurements. This was a methodology study using a descriptive cross-sectional design with 51 nursing students in 4th year of university...

  20. Stressful life events, vulnerable to stress and depression among ...

    African Journals Online (AJOL)

    The present study was carried out to observe the difference between male and female Eritrean students on the basis of stressful life events, vulnerable to stress and depression. Stressful life Events Questionnaire, Vulnerable to Stress Instrument and Beck Depression Scale were administered to gather information. The data ...

  1. Evaluation of Stress Levels of Professionals.

    Science.gov (United States)

    Schnorr, Janet K.; McWilliams, Jettie M.

    This study was conducted to analyze levels and areas of stress of professionals in selected service professions and to establish national norms of stress for these professions. The 60-item Tennessee Stress Scale-R (TSS-R) is a work-related stress inventory for professionals which provides a measure of stress in three areas: stress producers,…

  2. The interplay of stressful life events and coping skills on risk for suicidal behavior among youth students in contemporary China: a large scale cross-sectional study.

    Science.gov (United States)

    Tang, Fang; Xue, Fuzhong; Qin, Ping

    2015-07-31

    Stressful life events are common among youth students and may induce psychological problems and even suicidal behaviors in those with poor coping skills. This study aims to assess the influence of stressful life events and coping skills on risk for suicidal behavior and to elucidate the underlying mechanism using a large sample of university students in China. 5972 students, randomly selected from 6 universities, completed the questionnaire survey. Logistic regression analysis was performed to estimate the effect of stressful life events and coping skills on risk for suicidal behavior. Bayesian network was further adopted to probe their probabilistic relationships. Of the 5972 students, 7.64% reported the presence of suicidal behavior (attempt or ideation) within the past one year period. Stressful life events such as strong conflicts with classmates and a failure in study exam constituted strong risk factors for suicidal behavior. The influence of coping skills varied according to the strategies adapted toward problems with a high score of approach coping skills significantly associated with a reduced risk of suicidal behavior. The Bayesian network indicated that the probability of suicidal behavior associated with specific life events was to a large extent conditional on coping skills. For instance, a stressful experience of having strong conflicts with classmates could result in a probability of suicidal behavior of 21.25% and 15.36% respectively, for female and male students with the score of approach coping skills under the average. Stressful life events and deficient coping skills are strong risk factors for suicidal behavior among youth students. The results underscore the importance of prevention efforts to improve coping skills towards stressful life events.

  3. Perceived Stress among Deaf Adults

    Science.gov (United States)

    Jones, Elaine G.; Ouellette, Sue E.; Kang, Youngmi

    2006-01-01

    The Present Article describes the effectiveness of stress management classes in decreasing perceived stress among Deaf adults. Deaf adults may experience unique stressors, in addition to circumstances associated with increased stress in the general population. The Perceived Stress Scale (S. Cohen, Kamarck, & Mermelstein, 1983) was used as a…

  4. Versão brasileira da Escala de Estresse Percebido: tradução e validação para idosos Brazilian version of the Perceived Stress Scale: translation and validation for the elderly

    Directory of Open Access Journals (Sweden)

    Caroline Di Bernardi Luft

    2007-08-01

    Full Text Available OBJETIVO: Traduzir a Escala de Estresse Percebido para a língua portuguesa do Brasil e verificar sua validade para mensurar o estresse percebido de idosos brasileiros. MÉTODOS: A escala foi traduzida e testada em sua versão completa, com 14 questões e na reduzida, com dez questões. A tradução obedeceu às etapas de tradução, tradução reversa e revisão por um comitê. A escala traduzida foi aplicada, por meio de entrevista, a 76 idosos com idade média de 70,04 anos (DP=6,34; mín: 60; máx: 84. A consistência interna foi verificada por meio do coeficiente alfa de Cronbach e a validade de construto, por análise fatorial exploratória com rotação ortogonal pelo método varimax. As médias das versões completa e reduzida foram analisadas comparando o estresse percebido em função da auto-avaliação da saúde, nível econômico percebido, estado civil, condições de residência, entre outras. RESULTADOS: Quanto à confiabilidade, a versão completa apresentou consistência interna semelhante (r=0,82 à reduzida (r=0,83. A análise fatorial revelou a existência de dois fatores para a completa e um para a reduzida. A questão 12 apresentou as menores cargas fatoriais. Ao analisar a possibilidade de a escala diferenciar o estresse percebido em função das variáveis, verificou-se que a versão completa obteve maiores diferenças no estresse do que a reduzida. CONCLUSÕES: A Escala de Estresse Percebido mostrou-se clara e confiável para mensurar o estresse percebido de idosos brasileiros, apresentando qualidades psicométricas adequadas.OBJECTIVE: To translate the Perceived Stress Scale into Brazilian Portuguese, and to assess its validity for measuring perceived stress of Brazilian elderly. METHODS: The scale was translated and tested in its full version including 14 questions and in a shortened version including ten questions. The whole translation process consisted of translation, back-translation and committee review. The

  5. Watershed Scale Analysis of Groundwater Surface Water Interactions and Its Application to Conjunctive Management under Climatic and Anthropogenic Stresses over the US Sunbelt

    Science.gov (United States)

    Seo, Seung Beom

    Although water is one of the most essential natural resources, human activities have been exerting pressure on water resources. In order to reduce these stresses on water resources, two key issues threatening water resources sustainability - interaction between surface water and groundwater resources and groundwater withdrawal impacts of streamflow depletion - were investigated in this study. First, a systematic decomposition procedure was proposed for quantifying the errors arising from various sources in the model chain in projecting the changes in hydrologic attributes using near-term climate change projections. Apart from the unexplained changes by GCMs, the process of customizing GCM projections to watershed scale through a model chain - spatial downscaling, temporal disaggregation and hydrologic model - also introduces errors, thereby limiting the ability to explain the observed changes in hydrologic variability. Towards this, we first propose metrics for quantifying the errors arising from different steps in the model chain in explaining the observed changes in hydrologic variables (streamflow, groundwater). The proposed metrics are then evaluated using a detailed retrospective analyses in projecting the changes in streamflow and groundwater attributes in four target basins that span across a diverse hydroclimatic regimes over the US Sunbelt. Our analyses focused on quantifying the dominant sources of errors in projecting the changes in eight hydrologic variables - mean and variability of seasonal streamflow, mean and variability of 3-day peak seasonal streamflow, mean and variability of 7-day low seasonal streamflow and mean and standard deviation of groundwater depth - over four target basins using an Penn state Integrated Hydrologic Model (PIHM) between the period 1956-1980 and 1981-2005. Retrospective analyses show that small/humid (large/arid) basins show increased (reduced) uncertainty in projecting the changes in hydrologic attributes. Further

  6. Stress and stress counselling.

    OpenAIRE

    Matheson, K. H.

    1990-01-01

    This is a report by the 1989 National Association of Clinical Tutors Wyeth Travelling Fellow to the United States of America. The stresses of postgraduate training and attempts to modify these are described, including stress counselling. The significance of stress and the relevance of the findings for postgraduate training in the United Kingdom are considered.

  7. A Three-Dimensional Scale-adaptive Turbulent Kinetic Energy Model in ARW-WRF Model

    Science.gov (United States)

    Zhang, Xu; Bao, Jian-Wen; Chen, Baode

    2017-04-01

    A new three-dimensional (3D) turbulent kinetic energy (TKE) subgrid mixing model is developed to address the problem of simulating the convective boundary layer (CBL) across the terra incognita in the Advanced Research version of the Weather Research and Forecasting Model (ARW-WRF). The new model combines the horizontal and vertical subgrid turbulent mixing into a single energetically consistent framework, in contrast to the convectional one-dimensional (1D) planetary boundary layer (PBL) schemes. The transition between large-eddy simulation (LES) and mesoscale limit is accomplished in the new scale-adaptive model. A series of dry CBL and real-time simulations using the WRF model are carried out, in which the newly-developed, scale-adaptive, more general and energetically consistent TKE-based model is compared with the conventional 1D TKE-based PBL schemes for parameterizing vertical subgrid turbulent mixing against the WRF LES dataset and observations. The characteristics of the WRF-simulated results using the new and conventional schemes are compared. The importance of including the nonlocal component in the vertical buoyancy specification in the newly-developed general TKE-based scheme is illustrated. The improvements of the new scheme over convectional PBL schemes across the terra incognita can be seen in the partitioning of vertical flux profiles. Through comparing the results from the simulations against the WRF LES dataset and observations, we will show the feasibility of using the new scheme in the WRF model in the lieu of the conventional PBL parameterization schemes.

  8. A Large-scale Finite Element Model on Micromechanical Damage and Failure of Carbon Fiber/Epoxy Composites Including Thermal Residual Stress

    Science.gov (United States)

    Liu, P. F.; Li, X. K.

    2017-09-01

    The purpose of this paper is to study micromechanical progressive failure properties of carbon fiber/epoxy composites with thermal residual stress by finite element analysis (FEA). Composite microstructures with hexagonal fiber distribution are used for the representative volume element (RVE), where an initial fiber breakage is assumed. Fiber breakage with random fiber strength is predicted using Monte Carlo simulation, progressive matrix damage is predicted by proposing a continuum damage mechanics model and interface failure is simulated using Xu and Needleman's cohesive model. Temperature dependent thermal expansion coefficients for epoxy matrix are used. FEA by developing numerical codes using ANSYS finite element software is divided into two steps: 1. Thermal residual stresses due to mismatch between fiber and matrix are calculated; 2. Longitudinal tensile load is further exerted on the RVE to perform progressive failure analysis of carbon fiber/epoxy composites. Numerical convergence is solved by introducing the viscous damping effect properly. The extended Mori-Tanaka method that considers interface debonding is used to get homogenized mechanical responses of composites. Three main results by FEA are obtained: 1. the real-time matrix cracking, fiber breakage and interface debonding with increasing tensile strain is simulated. 2. the stress concentration coefficients on neighbouring fibers near the initial broken fiber and the axial fiber stress distribution along the broken fiber are predicted, compared with the results using the global and local load-sharing models based on the shear-lag theory. 3. the tensile strength of composite by FEA is compared with those by the shear-lag theory and experiments. Finally, the tensile stress-strain curve of composites by FEA is applied to the progressive failure analysis of composite pressure vessel.

  9. Childhood Stress

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Childhood Stress KidsHealth / For Parents / Childhood Stress What's in this ... and feel stress to some degree. Sources of Stress Stress is a function of the demands placed ...

  10. Stress Management

    Science.gov (United States)

    Healthy Lifestyle Stress management By Mayo Clinic Staff Stress basics Stress is a normal psychological and physical ... of life. Start practicing stress management techniques today. Stress relief The pace and challenges of modern life ...

  11. A Framework for Assessing Soil Moisture Deficit and Crop Water Stress at Multiple Space and Time Scales Under Climate Change Scenarios Using Model Platform, Satellite Remote Sensing, and Decision Support System

    KAUST Repository

    Mohanty, Binayak P.

    2016-11-03

    Better understanding of water cycle at different space–time scales would be a key for sustainable water resources, agricultural production, and ecosystems health in the twenty-first century. Efficient agricultural water management is necessary for sustainability of the growing global population. This warrants better predictive tools for aridity (based on precipitation, temperature, land use, and land cover), root zone (~top 1 m) soil moisture deficit, and crop water stress at farm, county, state, region, and national level, where decisions are made to allocate and manage the water resources. It will provide useful strategies for not only efficient water use but also for reducing potential risk of crop failure due to agricultural drought. Leveraging heavily on ongoing multiscale hydrologic modeling, data assimilation, soil moisture dynamics, and inverse model development research activities, and ongoing Land Data Assimilation (LDAS) and National Climate Assessment (NCA) indexing efforts we are developing a drought assessment framework. The drought assessment platform includes: (1) developing disaggregation methods for extracting various field-scale (1-km or less) climate indicators from the (SMOS, VIIRS, SMAP, AMSR-2) satellite / LDAS-based soil moisture in conjunction with a multimodel simulation–optimization approach using ensemble of Soil Vegetation Atmosphere Transfer, SVAT (Noah, CLM, VIC, Mosaic in LIS) models; (2) predicting farm/field-scale long-term root zone soil moisture status under various land management and climate scenarios for the past decades in hindcast mode and for the next decades in forecast mode across the USA using effective land surface parameters and meteorological input from Global Circulation Model (GCM) outputs; (3) assessing the potential risk of agricultural drought at different space–time scales across the USA based on predicted root zone soil moisture; and (4) evaluating various water management and cropping practices (e

  12. Types of Stresses Experienced by Professionals.

    Science.gov (United States)

    Gadzella, Bernadette M.; And Others

    This study was conducted to examine the types of stresses experienced by professionals. Subjects were 56 persons enrolled in graduate classes who completed the Tennessee Stress Scale-L, Work Related Stress Inventory for Professionals. Besides the Total stress score, the instrument produced three subscale scores: Stress Producers, Coping…

  13. El estrés docente: elaboración de la escala ed-6 para su evaluación. [ Educational stress: elaboration of ed-6 scale for its assesment

    Directory of Open Access Journals (Sweden)

    Santiago Morán-Suárez

    2005-02-01

    Full Text Available The educational stress is an investigation topic that monopolizes or great number of studies. In the work that here is presented, the psychometrics properties of the scale ED-6 are analyzed. This scale was elaborated ad hoc to measure the stress or educational discomfort of face to their use in a wider frame of investigations on this phenomenon. As he/she will be able to be proven, the results show a reliability and acceptable validity, being conformed for 77 ítems and 6 dimensions: Anxiety, Depression, Pressures, Beliefs, Amotivation and Bad confrontation. It is expected that its use in future investigations is of great profit. El estrés docente es un tema de investigación que acapara un gran número de estudios. En el trabajo que aquí se presenta, se analizan las propiedades psicométricas de la escala ED-6,elaborada ad hoc para medir el estrés o malestar docente de cara a su utilización en un marco más amplio de investigaciones sobre este fenómeno. Como se podrá comprobar, los resultados muestran una fiabilidad y validez aceptable, quedando conformada por 77 ítems y 6 dimensiones: Ansiedad, Depresión, Presiones, Creencias, Desmotivación y Mal afrontamiento. Se espera que su uso en futuras investigaciones resulte de gran provecho

  14. Signaling stress? An analysis of phaeomelanin-based plumage color and individual corticosterone levels at two temporal scales in North American barn swallows, Hirundo rustica erythrogaster.

    Science.gov (United States)

    Jenkins, Brittany R; Vitousek, Maren N; Safran, Rebecca J

    2013-09-01

    Sexually selected traits confer greater reproductive benefits to individuals with more elaborate forms of the signal. However, whether these signals convey reliable information about the physiology underlying trait development remains unknown in many species. The steroid hormone corticosterone (CORT) mediates important physiological and behavioral processes during the vertebrate stress response, and CORT secretion itself can be modulated by melanocortins. Thus, sexually selected melanin-based plumage coloration could function as an honest signal of an individual's ability to respond to stressors. This hypothesis was tested in North American barn swallows, Hirundo rustica erythrogaster, where males with darker ventral plumage color exhibit higher phaeomelanin content and are more successful at reproduction. Because reproductive behavior occurs months after plumage signals are developed, we also addressed the potential temporal disconnect of physiological state during trait development and trait advertisement by analyzing three different measurements of CORT levels in adult males during the breeding season (trait advertisement) and in nestling males while they were growing their feathers (trait development). Variation in adult plumage color did not predict baseline or stress-induced CORT, or stress responsiveness. Likewise, there was no relationship between nestling plumage color and any of the CORT measurements, but heavier nestlings had significantly lower baseline CORT. Our finding that a predominantly phaeomelanin-based trait is unrelated to circulating CORT suggests that phaeomelanin and eumelanin signals may convey different physiological information, and highlights the need for further study on the biochemical links between the hypothalamic-pituitary-adrenal (HPA) axis and the production of different melanin-based pigments. © 2013.

  15. Micron-scale channel formation by the release and bond-back of pre-stressed thin films : A finite element analysis

    NARCIS (Netherlands)

    Annabattula, R. K.; Huck, W. T. S.; Onck, P. R.

    Buckling of thin films on a rigid substrate during use or fabrication is a well-known but unwanted phenomenon. However, this phenomenon can also be exploited to generate well-controlled patterns at the micro and nano-scale. These patterned surfaces find various technological applications such as

  16. Intermetallic Growth Induced Large-Scale Void Growth and Cracking Failure in Line-Type Cu/Solder/Cu Joints Under Current Stressing

    Science.gov (United States)

    Chen, Zhuo; Tian, Wenya; Li, Junhui; Zhu, Wenhui

    2018-01-01

    In order to study the electromigration (EM) behavior of solder joints in electronics packaging, especially under high-current and high-temperature working conditions, line-type Cu/solder/Cu butting samples were prepared to observe the microstructural evolution under 1.0 × 104 A/cm2 current stressing. A prominent polarity effect was found such that the Cu6Sn5 intermetallic compound (IMC) layer at the anode side, which thickened linearly with time, was much thicker than that at the cathode side. Compared to the samples subjected to thermal aging at the same temperature of 180°C, EM enhanced the Cu3Sn growth at both the anode and the cathode. Two distinct types of damage were observed after extended duration of current stressing. Back-flow of Cu into Cu3Sn was found at the Cu3Sn/Cu6Sn5 interface of the anode side, causing large voids, while strip cracks developed at the cathode solder/Cu6Sn5 interface, causing a significant increase of joint electrical resistance. With the mass transport characteristics that determine the IMC growth and vacancy accumulation analyzed in detail at each interface, formation mechanisms of the two types of damages are discussed.

  17. Vertical Velocities in Cumulus Convection: Implications for Climate and Prospects for Realistic Simulation at Cloud Scale

    Science.gov (United States)

    Donner, Leo

    2014-05-01

    Cumulus mass fluxes are essential controls on the interactions between cumulus convection and large-scale flows. Cumulus parameterizations have generally been built around them, and these parameterizations are basic components of climate models. Several important questions in climate science depend also on cumulus vertical velocities. Interactions between aerosols and convection comprise a prominent example, and scale-aware cumulus parameterizations that require explicit information about cumulus areas are another. Basic progress on these problems requires realistic characterization of cumulus vertical velocities from observations and models. Recent deployments of dual-Doppler radars are providing unprecedented observations, which can be compared against cloud-resolving models (CRMs). The CRMs can subsequently be analyzed to develop and evaluate parameterizations of vertical velocities in climate models. Vertical velocities from several cloud models will be compared against observations in this presentation. CRM vertical velocities will be found to depend strongly on model resolution and treatment of sub-grid turbulence and microphysics. Although many current state-of-science CRMs do not simulate vertical velocities well, recent experiments with these models suggest that with appropriate treatments of sub-grid turbulence and microphysics robustly realistic modeling of cumulus vertical velocities is possible.

  18. Manage Stress

    Science.gov (United States)

    ... Manage Stress Print This Topic En español Manage Stress Browse Sections The Basics Overview Signs and Health ... and Health Effects What are the signs of stress? When people are under stress, they may feel: ...

  19. Stress Incontinence

    Science.gov (United States)

    Stress incontinence Overview Urinary incontinence is the unintentional loss of urine. Stress incontinence happens when physical movement or activity — such ... coughing, sneezing, running or heavy lifting — puts pressure (stress) on your bladder. Stress incontinence is not related ...

  20. Measuring symptoms of post-traumatic stress disorder in people with intellectual disabilities: the development and psychometric properties of the Impact of Event Scale-Intellectual Disabilities (IES-IDs).

    Science.gov (United States)

    Hall, James C; Jobson, Laura; Langdon, Peter E

    2014-09-01

    The aims of the study were to (1) revise the Impact of Event Scale-Revised for use with people with intellectual disabilities (IDs), creating the Impact of Event Scale-Intellectual Disabilities (IES-IDs), (2) assess the reliability of the IES-IDs, and (3) compare the IES-IDs to an existing measure trauma-related symptomatology, namely the Lancaster and Northgate Trauma Scale (LANTS), along with measures of anxiety and depression. Forty adults with IDs who had experienced at least one traumatic event were recruited and completed the IES-IDs and the LANTS on two occasions, separated by 2 weeks. Participants also completed the Glasgow Depression Scale and the Glasgow Anxiety Scale, along with the Trauma Information Form which was used to collect information about trauma history. Fifteen per cent of the sample had encountered five or more traumatic events. The IES-IDs and the LANTS had good to excellent internal consistency and test-retest reliability. Both measures correlated with self-report measures of depression and anxiety, although the strength of this correlation was greater with the LANTS. There was a significant positive correlation between trauma frequency and the IES-IDs, while trauma frequency did not correlate with the LANTS. Both the IES-IDs and the LANTS appear to have good reliability. There is a lack of well-developed questionnaires that can be used to assess symptoms of post-traumatic stress disorder (PTSD) in people with intellectual disabilities. The Impact of Event Scale-Revised was augmented creating the Impact of Event Scale-Intellectual Disabilities (IES-IDs). The IES-IDs was shown to have good psychometric properties. The IES-IDs was compared to the Lancaster and Northgate Trauma Scale (LANTS), but the LANTS did not correlate with trauma frequency. However, this study had a small sample size, and a much larger study is needed to examine the factor structure of both the IES-IDs and the LANTS. Future studies should attempt to recruit people with

  1. Optimal Length Scale for a Turbulent Dynamo.

    Science.gov (United States)

    Sadek, Mira; Alexakis, Alexandros; Fauve, Stephan

    2016-02-19

    We demonstrate that there is an optimal forcing length scale for low Prandtl number dynamo flows that can significantly reduce the required energy injection rate. The investigation is based on simulations of the induction equation in a periodic box of size 2πL. The flows considered are the laminar and turbulent ABC flows forced at different forcing wave numbers k_{f}, where the turbulent case is simulated using a subgrid turbulence model. At the smallest allowed forcing wave number k_{f}=k_{min}=1/L the laminar critical magnetic Reynolds number Rm_{c}^{lam} is more than an order of magnitude smaller than the turbulent critical magnetic Reynolds number Rm_{c}^{turb} due to the hindering effect of turbulent fluctuations. We show that this hindering effect is almost suppressed when the forcing wave number k_{f} is increased above an optimum wave number k_{f}L≃4 for which Rm_{c}^{turb} is minimum. At this optimal wave number, Rm_{c}^{turb} is smaller by more than a factor of 10 than the case forced in k_{f}=1. This leads to a reduction of the energy injection rate by 3 orders of magnitude when compared to the case where the system is forced at the largest scales and thus provides a new strategy for the design of a fully turbulent experimental dynamo.

  2. Estrutura fatorial e propriedades psicométricas da Escala de stress infantil adaptada para uma amostra de crianças cegas = Factor structure and psychometric properties of the Infatile Stress Scale adapted to a blind child sample

    Directory of Open Access Journals (Sweden)

    Filgueiras, Alberto

    2013-01-01

    Full Text Available Métodos e instrumentos específicos para a avaliação psicológica em crianças cegas são escassos. Contudo, é possível a adaptação de medidas psicológicas de indivíduos videntes para o contexto da cegueira. Com o objetivo de estudar um método confiável na mensuração do estresse nessa população, analisamos as propriedades psicométricas e a estrutura fatorial da Escala de Stress Infantil (ESI. O instrumento foi aplicado em 92 crianças cegas congênitas alunas do ensino fundamental do Instituto Benjamin Constant do Rio de Janeiro. A análise fatorial exploratória revelou quatro fatores, conforme esperado, mostrando boa consistência interna das quatro diferentes dimensões da escala. A análise fatorial confirmatória detectou o modelo com um fator como o melhor, como já apontado pela literatura, o que demonstra que as quatro dimensões convergem para um constructo único: estresse. A confiabilidade da escala mostrou-se satisfatória apresentando alfa de Cronbach de 0,91. Esse estudo dá subsídios para a confiabilidade e para a estrutura unifatorial da ESI para medir o estresse em crianças cegas

  3. A micro-scale hot wire anemometer based on low stress (Ni/W) multi-layers deposited on nano-crystalline diamond for air flow sensing

    Science.gov (United States)

    Talbi, A.; Gimeno, L.; Gerbedoen, J.-C.; Viard, R.; Soltani, A.; Mortet, V.; Preobrazhensky, V.; Merlen, A.; Pernod, P.

    2015-12-01

    A linear array of microscale thermal anemometers has been designed, fabricated and characterized. The sensitive element consists of a self-compensated-stress multilayer (Ni/W) patterned to form a wire with length, width, and thickness close to 200 μm, 5 μm and 2 μm respectively. The wire is deposited and supported by prongs made of nano-crystalline diamond (NCD) of about 2 μm in thickness. Due to its high Young’s modulus, NCD allows a very high mechanical toughness without the need for thicker support for the hot wire. Also, depending on grain size, the NCD is able to present thermal conductivity smaller than 10 W mK-1, providing good thermal insulation from the substrate and less conductive end losses to the prongs. The sensor was characterized experimentally. Its electrical and thermal properties were obtained first in the absence of fluid flow. The results confirm the effectiveness of thermal insulation and the mechanical robustness of the structure. The fluidic characterizations were performed and analysed in the case of an airflow with velocities of up to 30 m s-1.

  4. The effects of perceived stress, traits, mood states, and stressful daily events on salivary cortisol

    NARCIS (Netherlands)

    vanEck, M; Berkhof, H; Nicolson, N; Sulon, J

    1996-01-01

    This study examined the effects of perceived stress and related individual characteristics, mood states, and stressful daily events on salivary cortisol levels. Forty-one ''high stress'' and 46 ''low stress'' subjects were selected on the basis of Perceived Stress Scale scores from a sample of male,

  5. Stresses in Dolosse

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Liu, Zhou; Howell, Gary L.

    1991-01-01

    Failures of rubble mound breakwaters armoured with complex types of unreinforced concrete armour units are often due to breakage. This happens when the stresses exceed the material strength. Sufficient parametric studies of the stresses are not yet available to produce design diagrams for structu......Failures of rubble mound breakwaters armoured with complex types of unreinforced concrete armour units are often due to breakage. This happens when the stresses exceed the material strength. Sufficient parametric studies of the stresses are not yet available to produce design diagrams...... for structural integrity. The paper presents the results and the analyses of model tests with 200 kg and 200 g load-cell instrumented Dolosse. Static stresses and wave generated stresses were studied as well as model and scale effects. A preliminary design diagram for Dolosse is presented as well....

  6. A large-scale layered stationary convection of a incompressible viscous fluid under the action of shear stresses at the upper boundary. Velocity field investigation

    Directory of Open Access Journals (Sweden)

    Natal'ya V. Burmasheva

    2017-05-01

    Full Text Available The exact solution of the definition of convective motions in a layered large-scale flows of a viscous incompressible fluid in a steady case is considered. It was shown that the received problem is, firstly, overdetermined and, secondly, a nonlinear (due to the presence of members of a convective derivative in a heat conduction equation. Also it was shown that the solution class choice can eliminate the override, and the specification of a boundary conditions can reduce the problem to the study of a thermal capillary convection (convection Benard–Marangoni. Then conditions of the counterflow appearance are defined, and their possible amount is investigated. In addition, the analysis of the nonvortex region in the test flow is made. And it was shown that under certain combinations of system parameters the vortex can change the direction.

  7. Nuclear stress test

    Science.gov (United States)

    ... Persantine stress test; Thallium stress test; Stress test - nuclear; Adenosine stress test; Regadenoson stress test; CAD - nuclear stress; Coronary artery disease - nuclear stress; Angina - nuclear ...

  8. Caregiver Stress

    Science.gov (United States)

    ... Home A-Z Health Topics Caregiver stress Caregiver stress > A-Z Health Topics Caregiver fact sheet (PDF, ... receive Publications email updates Enter email Submit Caregiver stress Caregivers care for someone with an illness, injury, ...

  9. Physics and Dynamics Coupling Across Scales in the Next Generation CESM. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bacmeister, Julio T. [University Corporation for Atmospheric Research (UCAR), Boulder, CO (United States)

    2015-06-12

    This project examines physics/dynamics coupling, that is, exchange of meteorological profiles and tendencies between an atmospheric model’s dynamical core and its various physics parameterizations. Most model physics parameterizations seek to represent processes that occur on scales smaller than the smallest scale resolved by the dynamical core. As a consequence a key conceptual aspect of parameterizations is an assumption about the subgrid variability of quantities such as temperature, humidity or vertical wind. Most existing parameterizations of processes such as turbulence, convection, cloud, and gravity wave drag make relatively ad hoc assumptions about this variability and are forced to introduce empirical parameters, i.e., “tuning knobs” to obtain realistic simulations. These knobs make systematic dependences on model grid size difficult to quantify.

  10. Determinants of academic stress and stress-related selfmedication ...

    African Journals Online (AJOL)

    Methods: A cross-sectional survey was conducted among undergraduate students of pharmacy and medical colleges of the university. The study used Perceived Stress Scale (PSS) to document academic stress. The responses of the students were analyzed using SPSS version 22. Results: As many as 51.6 % of students' ...

  11. A Structural Model of Stress, Motivation, and Academic Performance in Medical Students

    National Research Council Canada - National Science Library

    Park, Jangho; Chung, Seockhoon; An, Hoyoung; Park, Seungjin; Lee, Chul; Kim, Seong Yoon; Lee, Jae-Dam; Kim, Ki-Soo

    2012-01-01

    .... Psychological parameters were assessed with the Medical Stress Scale, Minnesota Multiphasic Personality Inventory, Hamilton Depression Scale, Beck Depression Inventory, and Academic Motivation Scale...

  12. [Autism spectrum disorder and evaluation of perceived stress parents and professionals: Study of the psychometric properties of a French adaptation of the Appraisal of Life Event Scale (ALES-vf)].

    Science.gov (United States)

    Cappe, É; Poirier, N; Boujut, É; Nader-Grosbois, N; Dionne, C; Boulard, A

    2017-08-01

    Autism and related disorders are grouped into the category of « Autism Spectrum Disorder » (ASD) in the DSM-5. This appellation reflects the idea of a dimensional representation of autism that combines symptoms and characteristics that vary in severity and intensity. Despite common characteristics, there are varying degrees in intensity and in the onset of symptoms, ranging from a disability that can be very heavy with a total lack of communication and major disorders associated with the existence of a relative autonomy associated, sometimes, with extraordinary intellectual abilities. Parents are faced with several difficult situations, such as sleep disturbances, agitation, shouting, hetero violence, self-harm, learning difficulties, stereotyping, lack of social and emotional reciprocity, inappropriate behavior, etc. They can feel helpless and may experience stress related to these developmental and behavioral difficulties. The heterogeneity of symptoms, the presence of behavioral problems, the lack of reciprocity and autonomy also represent a challenge for practitioners in institutions and teachers at school. The objective of this research is to present the validation of a French translation of the Appraisal of Life Events Scale (ALES-vf) from Ferguson, Matthex and Cox, specifically adapted to the context of ASD. ALES was originally developed to operationalize the three dimensions of perceived stress (threat, loss and challenge) described by Lazarus and Folkman. ALES-vf was initially translated into French and adapted to the situation of parents of children with ASD. It was subsequently administered to 343 parents, 150 paramedical professionals involved with people with ASD, and 155 teachers from an ordinary school environment and from specialized schools, welcoming in their classroom at least one child with ASD. An exploratory factor analysis performed on data from 170 parents highlighted two exploratory models with four and three factors, slightly different

  13. Probabilistic Downscaling of Remote Sensing Data with Applications for Multi-Scale Biogeochemical Flux Modeling.

    Science.gov (United States)

    Stoy, Paul C; Quaife, Tristan

    2015-01-01

    Upscaling ecological information to larger scales in space and downscaling remote sensing observations or model simulations to finer scales remain grand challenges in Earth system science. Downscaling often involves inferring subgrid information from coarse-scale data, and such ill-posed problems are classically addressed using regularization. Here, we apply two-dimensional Tikhonov Regularization (2DTR) to simulate subgrid surface patterns for ecological applications. Specifically, we test the ability of 2DTR to simulate the spatial statistics of high-resolution (4 m) remote sensing observations of the normalized difference vegetation index (NDVI) in a tundra landscape. We find that the 2DTR approach as applied here can capture the major mode of spatial variability of the high-resolution information, but not multiple modes of spatial variability, and that the Lagrange multiplier (γ) used to impose the condition of smoothness across space is related to the range of the experimental semivariogram. We used observed and 2DTR-simulated maps of NDVI to estimate landscape-level leaf area index (LAI) and gross primary productivity (GPP). NDVI maps simulated using a γ value that approximates the range of observed NDVI result in a landscape-level GPP estimate that differs by ca 2% from those created using observed NDVI. Following findings that GPP per unit LAI is lower near vegetation patch edges, we simulated vegetation patch edges using multiple approaches and found that simulated GPP declined by up to 12% as a result. 2DTR can generate random landscapes rapidly and can be applied to disaggregate ecological information and compare of spatial observations against simulated landscapes.

  14. Heat Stress

    Science.gov (United States)

    ... Publications and Products Programs Contact NIOSH NIOSH HEAT STRESS Recommend on Facebook Tweet Share Compartir NEW OSHA- ... hot environments may be at risk of heat stress. Exposure to extreme heat can result in occupational ...

  15. Cold Stress

    Science.gov (United States)

    ... Publications and Products Programs Contact NIOSH NIOSH COLD STRESS Recommend on Facebook Tweet Share Compartir Workers who ... cold environments may be at risk of cold stress. Extreme cold weather is a dangerous situation that ...

  16. Negative Life Events Scale for Students (NLESS)

    Science.gov (United States)

    Buri, John R.; Cromett, Cristina E.; Post, Maria C.; Landis, Anna Marie; Alliegro, Marissa C.

    2015-01-01

    Rationale is presented for the derivation of a new measure of stressful life events for use with students [Negative Life Events Scale for Students (NLESS)]. Ten stressful life events questionnaires were reviewed, and the more than 600 items mentioned in these scales were culled based on the following criteria: (a) only long-term and unpleasant…

  17. Stress Fractures

    Science.gov (United States)

    Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

  18. Concepts of scale and scaling

    Science.gov (United States)

    Jianguo Wu; Harbin Li

    2006-01-01

    The relationship between pattern and process is of great interest in all natural and social sciences, and scale is an integral part of this relationship. It is now well documented that biophysical and socioeconomic patterns and processes operate on a wide range of spatial and temporal scales. In particular, the scale multiplicity and scale dependence of pattern,...

  19. DYPTOP: a cost-efficient TOPMODEL implementation to simulate sub-grid spatio-temporal dynamics of global wetlands and peatlands

    Directory of Open Access Journals (Sweden)

    B. D. Stocker

    2014-12-01

    TOPMODEL (DYPTOP, which predicts the extent of inundation based on a computationally efficient TOPMODEL implementation. This approach rests on an empirical, grid-cell-specific relationship between the mean soil water balance and the flooded area. DYPTOP combines the simulated inundation extent and its temporal persistency with criteria for the ecosystem water balance and the modelled peatland-specific soil carbon balance to predict the global distribution of peatlands. We apply DYPTOP in combination with the LPX-Bern DGVM and benchmark the global-scale distribution, extent, and seasonality of inundation against satellite data. DYPTOP successfully predicts the spatial distribution and extent of wetlands and major boreal and tropical peatland complexes and reveals the governing limitations to peatland occurrence across the globe. Peatlands covering large boreal lowlands are reproduced only when accounting for a positive feedback induced by the enhanced mean soil water holding capacity in peatland-dominated regions. DYPTOP is designed to minimize input data requirements, optimizes computational efficiency and allows for a modular adoption in Earth system models.

  20. Social Emotional Learning Skills and Educational Stress

    Science.gov (United States)

    Çelik, Ismail

    2013-01-01

    The basic aim of this research is to examine the predicting role of social emotional learning skills in educational stress. The participants were 238 adolescents at high school. In this study, the Social Emotional Learning Skills Scale and the Educational Stress Scale were used. The relationships between social emotional learning skills and…

  1. College Student Stress and Satisfaction with Life

    Science.gov (United States)

    Weinstein, Lawrence; Laverghetta, Antonio

    2009-01-01

    The following study was performed to determine if general life satisfaction is negatively correlated with college student stress. We administered the satisfaction with life scale (Diener et al., 1985), college student stress scale (Feldt, 2008) and a brief demographics survey to a sample of college students at a regional southwestern university in…

  2. Effects of Stress Reduction Information on Anxiety.

    Science.gov (United States)

    Connell, Patricia

    The negative sequelae that relocation to a nursing home has on the elderly is well documented. This study evaluated the effects of stress reduction information on the newly admitted patients' state anxiety based on self-reported distress using the Stresses in Institutional Care Scale. Anxiety was assessed using the Anxiety State Scale of the…

  3. Outcome Rating Scale and Session Rating Scale in Psychological Practice: Clinical Utility of Ultra-Brief Measures

    Science.gov (United States)

    Campbell, Alistair; Hemsley, Samantha

    2009-01-01

    The validity and reliability of the Outcome Rating Scale (ORS) and the Session Rating Scale (SRS) were evaluated against existing longer measures, including the Outcome Questionnaire-45, Working Alliance Inventory, Depression Anxiety Stress Scale-21, Quality of Life Scale, Rosenberg Self-Esteem Scale and General Self-efficacy Scale. The measures…

  4. Stress situations in dental practice.

    Science.gov (United States)

    Bourassa, M; Baylard, J F

    1994-01-01

    Several studies indicate that stress is inherently present in dental practice. The present study was conducted to help identify the factors underlying this stress and the relative contribution of each factor. A questionnaire presented participating dentists with 52 potentially-stressful situations related to dental practice. Respondents were asked to rate each situation on a five-point scale, using a range of responses that varied from "not stressful" to "exceedingly stressful," and "I don't know" to "not applicable." The present data are based on the ratings given by the 1,332 dentists practicing in Québec who answered the questionnaire (52 per cent). Ten situations received a mean score of greater than 3.0, and were therefore considered as above average stress-producing situations. The majority of these situations could be classified as being related either to dental procedures and office organization or to interpersonal relationships involving patients and/or office personnel. It was found that the older age groups showed significantly less stress for six of the 10 most stressful situations. This study has indicated the specific situations that most frequently lead to stress in dentists. The precise identification of these situations could lead to reduced stress through the elimination of its vague and insidious character. Furthermore, an understanding of the most common stress-causing situations allows the practitioner to take preventive measures to eliminate its damaging effects in the dental practice.

  5. Workshop on Human Activity at Scale in Earth System Models

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Melissa R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Aziz, H. M. Abdul [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Coletti, Mark A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kennedy, Joseph H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nair, Sujithkumar S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Omitaomu, Olufemi A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-01-26

    Changing human activity within a geographical location may have significant influence on the global climate, but that activity must be parameterized in such a way as to allow these high-resolution sub-grid processes to affect global climate within that modeling framework. Additionally, we must have tools that provide decision support and inform local and regional policies regarding mitigation of and adaptation to climate change. The development of next-generation earth system models, that can produce actionable results with minimum uncertainties, depends on understanding global climate change and human activity interactions at policy implementation scales. Unfortunately, at best we currently have only limited schemes for relating high-resolution sectoral emissions to real-time weather, ultimately to become part of larger regions and well-mixed atmosphere. Moreover, even our understanding of meteorological processes at these scales is imperfect. This workshop addresses these shortcomings by providing a forum for discussion of what we know about these processes, what we can model, where we have gaps in these areas and how we can rise to the challenge to fill these gaps.

  6. Work Stress

    OpenAIRE

    Roeters, Anne

    2014-01-01

    Most of us agree that stress is a growing problem within organizations. We hear about the postal workers who had killed fellow employees and supervisors, and then hear that a major cause of tension is at work. Friends tell us that they are stressed due to increased workload and he has to work overtime because the company is restructured. We read the polls that employees complain about the stress in trying to balance family life with the work. Stress is a dynamic condition in which an individu...

  7. Determinants of fatigue and stress.

    Science.gov (United States)

    Kocalevent, Rüya D; Hinz, Andreas; Brähler, Elmar; Klapp, Burghard F

    2011-07-20

    Fatigue can be triggered by previous perceived stress which may lead to impairment of performance and function. The purpose of the study was to investigate the relationship between fatigue and perceived stress. Health determinants including sociodemographic factors for associations between fatigue and perceived stress in the general population (N = 2,483) are outlined. Fatigue and stress were assessed with the Chalder Fatigue Scale (CFS) and the Perceived Stress Questionnaire (PSQ). Within the general population, 25.9% of male and 34.5% of female respondents reported moderate fatigue during the last six months; 9.7% of subjects reported substantial fatigue lasting six months or longer. An adjusted regression analysis (R2corr = .28, p rates of fatigue and perceived stress: female gender, divorce/separation, low social class and poor health status. We conclude that the two conditions overlap most in terms of socio-economic status and self-perceived health status.

  8. The Young and the Stressed

    DEFF Research Database (Denmark)

    Leppink, Eric W.; Odlaug, Brian L.; Lust, Katherine

    2016-01-01

    High levels of stress are common among young adults, particularly those enrolled in college. These degrees of stress have shown numerous deleterious effects across both academic and health variables. Findings regarding the role of stress in the presentation of impulse control disorders, particular...... among college students, are limited. This study examined potential associations between perceived stress, academic achievement, physical/mental health, and impulse control disorders in young adults. A total of 1805 students completed an online survey and were included in the analysis. Responders were...... grouped by their overall score on the Perceived Stress Scale into mild, moderate, or severe. Severe perceived stress was associated with worse academic achievement and worse physical health, as well as higher rates of psychiatric and impulsive disorders. These findings may suggest associations between...

  9. Stress magnitudes in the crust: constraints from stress orientation and relative magnitude data

    Science.gov (United States)

    Zoback, M.L.; Magee, M.

    1991-01-01

    The World Stress Map Project is a global cooperative effort to compile and interpret data on the orientation and relative magnitudes of the contemporary in situ tectonic stress field in the Earth's lithosphere. The intraplate stress field in both the oceans and continents is largely compressional with one or both of the horizontal stresses greater than the vertical stress. The regionally uniform horizontal intraplate stress orientations are generally consistent with either relative or absolute plate motions indicating that plate-boundary forces dominate the stress distribution within the plates. Current models of stresses due to whole mantle flow inferred from seismic topography models predict a general compressional stress state within continents but do not match the broad-scale horizontal stress orientations. The broad regionally uniform intraplate stress orientations are best correlated with compressional plate-boundary forces and the geometry of the plate boundaries. -from Authors

  10. Sensitivity of the scale partition for variational multiscale large-eddy simulation of channel flow

    Science.gov (United States)

    Holmen, Jens; Hughes, Thomas J. R.; Oberai, Assad A.; Wells, Garth N.

    2004-03-01

    The variational multiscale method has been shown to perform well for large-eddy simulation (LES) of turbulent flows. The method relies upon a partition of the resolved velocity field into large- and small-scale components. The subgrid model then acts only on the small scales of motion, unlike conventional LES models which act on all scales of motion. For homogeneous isotropic turbulence and turbulent channel flows, the multiscale model can outperform conventional LES formulations. An issue in the multiscale method for LES is choice of scale partition and sensitivity of the computed results to it. This is the topic of this investigation. The multiscale formulation for channel flows is briefly reviewed. Then, through the definition of an error measure relative to direct numerical simulation (DNS) results, the sensitivity of the method to the partition between large- and small-scale motions is examined. The error in channel flow simulations, relative to DNS results, is computed for various partitions between large- and small-scale spaces, and conclusions drawn from the results.

  11. Geopotential Stress

    DEFF Research Database (Denmark)

    Schiffer, Christian; Nielsen, S.B.

    Density heterogeneity in the Earth’s lithosphere causes lateral pressure variations. Horizontal gradients of the vertically integrated lithostatic pressure, the Geopotential Energy (GPE), are a source of stresses (Geopotential Stress) that contribute to the Earth’s Stress Field. In theory the GPE...... is linearly related to the lithospheric part of the Geoid. The Geopotential Stress can be calculated if either the density structure and as a consequence the GPE or the lithospheric contribution to the Geoid is known. The lithospheric Geoid is usually obtained by short pass filtering of satellite Geoid...... are not entirely suitable for the stress calculations but can be compiled and adjusted. We present an approach in which a global lithospheric density model based on CRUST2.0 is obtained by simultaneously fitting topography and surface heat flow in the presence of isostatic compensation and long-wavelength lateral...

  12. [Stress fractures].

    Science.gov (United States)

    Uhl, M

    2016-07-01

    Bone stress injuries are due to repetitive mechanical overuse of the skeleton and occur as a result of microscopic lesions sustained when bone is subjected to repeated submaximal stress. Over time accumulation of such injuries can lead to bone failure and fractures. Stress-related bone injuries are relatively common among otherwise healthy persons who have recently started new or intensified forms of physical training activities. Stress injuries lead to typical findings on radiography, bone scintigraphy, computed tomography (CT) and magnetic resonance imaging (MRI) and need to be discriminated from other conditions, in particular infections and neoplasms. Stress fractures must be differentiated from insufficiency fractures that occur in bones with reduced mechanical resistance or disturbed structure.

  13. Stress in Medical Students

    Directory of Open Access Journals (Sweden)

    Barikani A

    2007-04-01

    Full Text Available Background and purpose: Beginning medicine for the first time as a academic program is a very stressful for medical students. This study is an attempt to determine stress in medical students of Qazvin University of Medical Sciences and Health Services. Methods: A survey of randomly selected medical students of all years in Quazvin medical university were conducted based on a questionnaire including demographic data and items examining possible sources of anxiety based on our experience with medical students and a scale to measure the anxiety experienced by the students as well as an item asking students how satisfied they are with studying medicine were given to all subjects. On the questionnaire space were provided for respondent to express their comments on each factor they identify as source of stress. To measure the anxiety the students were asked to mark the level of anxiety they experienced on a six point scale. Analyses of data was conducted with SPSS version 12. Relation between variables was assessed with chi-square test with a significance level of <0.05. Results: Of the 200 students who received questionnaires 155 completed and returned them ( response rate = 77.7%. Of all respondent , 123 (79.4% were female, 140 (90.3% were unmarried. Nearly half the students (45% experienced intermediate or higher levels of stress. More frequently expressed factors leading to stress were “ initial adaptation to the program” (84.5% ,apprehension of exam (41.3% and economic issues(32.4%. Conclusion: Our findings suggests that many stressors are present in the path to become a doctor. A more detailed investigation of these factor throughout universities of medicine and based on that introducing procedures centrally and university-based will undoubtedly help tackle many of these problems. Key words: STRESS FACTORS, MEDICAL STUDENTS

  14. Resiliency against stress among athletes

    Directory of Open Access Journals (Sweden)

    Kamila Litwic-Kaminska

    2015-10-01

    Full Text Available Background The aim of this paper is to describe the results of a study concerning the relationship between resiliency and appraisal of a stressful situation, anxiety reactions and undertaken methods of coping among sportsmen. Participants and procedure The research concerned 192 competitors who actively train in one of the Olympic disciplines – individual or team. We used the following instruments: Resiliency Assessment Scale (SPP-25; Stress Appraisal Questionnaire A/B; Reactions to Competition Questionnaire; Coping Inventory for Stressful Situations (CISS; Sport Stress Coping Strategies Questionnaire (SR3S, self-constructed. Results Athletes most frequently apply positive types of stress appraisal, and they cope with stress through a task-oriented style during competitions. There is a relationship between the level of resiliency and the analysed aspects of the process of stress. The higher the resiliency, the more positive is the appraisal of a stressful situation and the more task-oriented are the strategies applied. Similarly, in everyday situations resilient sportspeople positively appraise difficult situations and undertake mostly task-oriented strategies. Resiliency is connected with less frequently experiencing reactions in the form of anxiety. Conclusions The obtained results, similarly to previous research, suggest that resiliency is connected with experiencing positive emotions. It causes more frequent appraisal of stressful situations as a challenge. More resilient people also choose more effective and situation-appropriate coping strategies. Therefore they are more resistant to stress.

  15. Learn to manage stress

    Science.gov (United States)

    Stress - managing; Stress - recognizing; Stress - relaxation techniques ... LEARN TO RECOGNIZE STRESS The first step in managing stress is recognizing it in your life. Everyone feels stress in a different way. ...

  16. A first large-scale flood inundation forecasting model

    Science.gov (United States)

    Schumann, G. J.-P.; Neal, J. C.; Voisin, N.; Andreadis, K. M.; Pappenberger, F.; Phanthuwongpakdee, N.; Hall, A. C.; Bates, P. D.

    2013-10-01

    At present continental to global scale flood forecasting predicts at a point discharge, with little attention to detail and accuracy of local scale inundation predictions. Yet, inundation variables are of interest and all flood impacts are inherently local in nature. This paper proposes a large-scale flood inundation ensemble forecasting model that uses best available data and modeling approaches in data scarce areas. The model was built for the Lower Zambezi River to demonstrate current flood inundation forecasting capabilities in large data-scarce regions. ECMWF ensemble forecast (ENS) data were used to force the VIC (Variable Infiltration Capacity) hydrologic model, which simulated and routed daily flows to the input boundary locations of a 2-D hydrodynamic model. Efficient hydrodynamic modeling over large areas still requires model grid resolutions that are typically larger than the width of channels that play a key role in flood wave propagation. We therefore employed a novel subgrid channel scheme to describe the river network in detail while representing the floodplain at an appropriate scale. The modeling system was calibrated using channel water levels from satellite laser altimetry and then applied to predict the February 2007 Mozambique floods. Model evaluation showed that simulated flood edge cells were within a distance of between one and two model resolutions compared to an observed flood edge and inundation area agreement was on average 86%. Our study highlights that physically plausible parameter values and satisfactory performance can be achieved at spatial scales ranging from tens to several hundreds of thousands of km2 and at model grid resolutions up to several km2.

  17. Relationship among perceived stress, anxiety, depression and craniocervical pain in nursing professionals under stress at work

    Directory of Open Access Journals (Sweden)

    Daniela Pozzebon

    Full Text Available Abstract Introduction: The appearance and evolution of some clinical pain conditions may be influenced by stress and other psychosocial factors. Face, head and cervical muscles may increase their activity and tension in the presence of stress, leading to craniocervicomandibular pain in individuals exposed to stress. Objective: To assess the relationship among perceived stress, anxiety, depression and craniocervicomandibular pain in nursing professionals under stress at work. Materials and Methods: Forty-three women under stress at work, according to the Job Stress Scale (JSS, were assessed by the Perceived Stress Scale (PSS, the Hospital Anxiety and Depression Scale (HADS, pressure pain threshold, measured by algometry, and muscle sensitivity to hand palpation of the masticatory and cervical muscles. Results: A low moderate level of perceived stress was found in 62.79% of the sample, anxiety in 11.63% and depression in 9.30%. The psychosocial scales correlated with each other. No correlation was found between pressure pain threshold and perceived stress, anxiety and depression. The level of pain to hand palpation correlated with the perceived stress scores. Conclusion: Pressure pain threshold was not influenced by the psychosocial factors assessed. Pain intensity to hand palpation, however, was higher as the perception of stress increased.

  18. Maslowian Scale.

    Science.gov (United States)

    Falk, C.; And Others

    The development of the Maslowian Scale, a method of revealing a picture of one's needs and concerns based on Abraham Maslow's levels of self-actualization, is described. This paper also explains how the scale is supported by the theories of L. Kohlberg, C. Rogers, and T. Rusk. After a literature search, a list of statements was generated…

  19. Environmental stress

    Energy Technology Data Exchange (ETDEWEB)

    Evans, G.W. (ed.)

    1984-01-01

    Environmental stresses from noise, heat, air pollution, and crowding cause physical dysfunctions in people. Nineteen contributors review and integrate these stresses to show how they affect human needs in hospital, school, office, and neighborhood settings and how this information can be used to understand human behavior in the designed environment. The final section of the book explores how social science research can be used to influence public policy in the area of environmental decisions. The authors' concern focus on the limitations of laboratory research on behavioral responses to stress. 24 footnotes, 10 figures, 7 tables

  20. Friction stress effects on mode I crack growth predictions

    NARCIS (Netherlands)

    Chen, Q.; Deshpande, V.S.; Giessen, E. van der; Needleman, A.

    2003-01-01

    The effect of a lattice friction stress on the monotonic growth of a plane strain mode I crack under small-scale yielding conditions is analyzed using discrete dislocation plasticity. When the friction stress is increased from zero to half the dislocation nucleation stress, the crack tip stress

  1. Helicity scalings

    Energy Technology Data Exchange (ETDEWEB)

    Plunian, F [ISTerre, CNRS, Universite Joseph Fourier, Grenoble (France); Lessinnes, T; Carati, D [Physique Statistique et Plasmas, Universite Libre de Bruxelles (Belgium); Stepanov, R, E-mail: Franck.Plunian@ujf-grenoble.fr [Institute of Continuous Media Mechanics of the Russian Academy of Science, Perm (Russian Federation)

    2011-12-22

    Using a helical shell model of turbulence, Chen et al. (2003) showed that both helicity and energy dissipate at the Kolmogorov scale, independently from any helicity input. This is in contradiction with a previous paper by Ditlevsen and Giuliani (2001) in which, using a GOY shell model of turbulence, they found that helicity dissipates at a scale larger than the Kolmogorov scale, and does depend on the helicity input. In a recent paper by Lessinnes et al. (2011), we showed that this discrepancy is due to the fact that in the GOY shell model only one helical mode (+ or -) is present at each scale instead of both modes in the helical shell model. Then, using the GOY model, the near cancellation of the helicity flux between the + and - modes cannot occur at small scales, as it should be in true turbulence. We review the main results with a focus on the numerical procedure needed to obtain accurate statistics.

  2. Improving the representation of river-groundwater interactions in land surface modeling at the regional scale: Observational evidence and parameterization applied in the Community Land Model

    KAUST Repository

    Zampieri, Matteo

    2012-02-01

    Groundwater is an important component of the hydrological cycle, included in many land surface models to provide a lower boundary condition for soil moisture, which in turn plays a key role in the land-vegetation-atmosphere interactions and the ecosystem dynamics. In regional-scale climate applications land surface models (LSMs) are commonly coupled to atmospheric models to close the surface energy, mass and carbon balance. LSMs in these applications are used to resolve the momentum, heat, water and carbon vertical fluxes, accounting for the effect of vegetation, soil type and other surface parameters, while lack of adequate resolution prevents using them to resolve horizontal sub-grid processes. Specifically, LSMs resolve the large-scale runoff production associated with infiltration excess and sub-grid groundwater convergence, but they neglect the effect from loosing streams to groundwater. Through the analysis of observed data of soil moisture obtained from the Oklahoma Mesoscale Network stations and land surface temperature derived from MODIS we provide evidence that the regional scale soil moisture and surface temperature patterns are affected by the rivers. This is demonstrated on the basis of simulations from a land surface model (i.e., Community Land Model - CLM, version 3.5). We show that the model cannot reproduce the features of the observed soil moisture and temperature spatial patterns that are related to the underlying mechanism of reinfiltration of river water to groundwater. Therefore, we implement a simple parameterization of this process in CLM showing the ability to reproduce the soil moisture and surface temperature spatial variabilities that relate to the river distribution at regional scale. The CLM with this new parameterization is used to evaluate impacts of the improved representation of river-groundwater interactions on the simulated water cycle parameters and the surface energy budget at the regional scale. © 2011 Elsevier B.V.

  3. Stress incontinence

    Science.gov (United States)

    ... to identify and control your pelvic floor muscles. Kegel exercises : These exercises can help keep the muscle ... stress incontinence and they bother you. Prevention Doing Kegel exercises may help prevent symptoms. Women who are ...

  4. Stress Management

    Science.gov (United States)

    ... events. People who were neglected or abused as children tend to be particularly vulnerable to stress. The same is true of people who have experienced violent crime, airplane crash survivors, military personnel, police officers and ...

  5. Stressing academia?

    DEFF Research Database (Denmark)

    Opstrup, Niels; Pihl-Thingvad, Signe

    short of individual need while high degrees of fit will mitigate stress. The analysis is based on a stratified random sample including 2127 researchers at 64 Danish university departments and covering all main areas of research and all academic staff categories. The results show that fit with regard......Incongruences between the individual and the organizational work context are potential stressors. The present study focuses on the relationship between a complementary need-supply fit and Danish researchers’ self-perceived job stress. Strain is expected to increase as organizational supplies fall...... to “soft” dimensions as freedom and independence in the job, personal and professional development at work, and receiving peer recognition is highly significant for the researchers’ self-perceived stress-level. The better the fit is the lower stress-levels the researchers’ on average report. On the other...

  6. Feline stress

    OpenAIRE

    Hirsch, Elin Netti

    2016-01-01

    Group-housing of domestic cats (Felis silvestris lybica) may induce a stress response with consequences such as cats developing infectious disease or problem behaviours. Still, there is no validated behavioural protocol to assess stress in cats. The aim of this thesis was to investigate the effect of group-housing of cats, and how this can be assessed non-invasively, by advancing a behavioural assessment tool. In Study I, frequency of group-housing and related issues such as management wa...

  7. Stress Management

    Directory of Open Access Journals (Sweden)

    Prof.Univ. Dr. Paul Marinescu

    2007-05-01

    Full Text Available In the post-modern management organizational leaders have the obligation of protecting their employees against factors that could cause damages to their potentially wealthy lives. Stress is such a factor. We shall attempt by means of the present article to draw attention on certain general aspects that should be taken into account in drafting plans for fighting against and diminishing the stress faced by the employees

  8. Stress, race, and body weight.

    Science.gov (United States)

    Kim, Karen Hye-cheon; Bursac, Zoran; DiLillo, Vicki; White, Della Brown; West, Delia Smith

    2009-01-01

    Stress has been identified as a significant factor in health and in racial/ethnic health disparities. A potential mediator in these relationships is body weight. Cross-sectional and longitudinal relationships between stress, race, and body weight were examined in an ethnically diverse sample of overweight and obese women with Type 2 diabetes (n = 217) enrolled in a behavioral weight loss program. Stress (Perceived Stress Scale) was assessed at baseline only and body weight (body mass index) was assessed at baseline and 6 months. Stress was not related to baseline body weight. With every 1 unit lower scored on the baseline stress measure, women lost 0.10 kg +/- .04 more at 6 months (p women were divided into tertiles based on baseline stress scores, those in the lowest stress group had significantly greater weight loss (5.2 kg +/- 4.9) compared with those in the highest stress group (3.0 kg +/- 4.0) (p weight loss has implications for enhancing weight loss programs for women with Type 2 diabetes. (c) 2009 APA, all rights reserved.

  9. Framing scales and scaling frames

    NARCIS (Netherlands)

    Lieshout, van M.; Dewulf, A.; Aarts, M.N.C.; Termeer, C.J.A.M.

    2009-01-01

    Policy problems are not just out there. Actors highlight different aspects of a situation as problematic and situate the problem on different scales. In this study we will analyse the way actors apply scales in their talk (or texts) to frame the complex decision-making process of the establishment

  10. Large Eddy Simulation of the ventilated wave boundary layer

    DEFF Research Database (Denmark)

    Lohmann, Iris P.; Fredsøe, Jørgen; Sumer, B. Mutlu

    2006-01-01

    A Large Eddy Simulation (LES) of (1) a fully developed turbulent wave boundary layer and (2) case 1 subject to ventilation (i.e., suction and injection varying alternately in phase) has been performed, using the Smagorinsky subgrid-scale model to express the subgrid viscosity. The model was found...... slows down the flow in the full vertical extent of the boundary layer, destabilizes the flow and decreases the mean bed shear stress significantly; whereas suction generally speeds up the flow in the full vertical extent of the boundary layer, stabilizes the flow and increases the mean bed shear stress...

  11. Tectonic stress in the plates

    Science.gov (United States)

    Richardson, R. M.; Solomon, S. C.; Sleep, N. H.

    1979-01-01

    In the present paper, the basic set of global intraplate stress orientation data is plotted and tabulated. Although the global intraplate stress field is complicated, several large-scale patterns can be seen. Much of stable North America is characterized by an E-W to NE-SW trend for the maximum compressive stress. South American lithosphere beneath the Andes, and perhaps farther east in the stable interior, has horizontal compressive stresses trending E-W to NW-SE. Western Europe north of the Alps is characterized by a NW-SE trending maximum horizontal compression, while Asia has the maximum horizontal compressive stress trending more nearly N-S, especially near the Himalayan front.

  12. Determinants of fatigue and stress

    Directory of Open Access Journals (Sweden)

    Brähler Elmar

    2011-07-01

    Full Text Available Abstract Background Fatigue can be triggered by previous perceived stress which may lead to impairment of performance and function. The purpose of the study was to investigate the relationship between fatigue and perceived stress. Method Health determinants including sociodemographic factors for associations between fatigue and perceived stress in the general population (N = 2,483 are outlined. Fatigue and stress were assessed with the Chalder Fatigue Scale (CFS and the Perceived Stress Questionnaire (PSQ. Results Within the general population, 25.9% of male and 34.5% of female respondents reported moderate fatigue during the last six months; 9.7% of subjects reported substantial fatigue lasting six months or longer. An adjusted regression analysis (R2corr = .28, p Conclusion We conclude that the two conditions overlap most in terms of socio-economic status and self-perceived health status.

  13. Full-Scale 3-D Finite Element Modeling of a Two-Loop Pressurized Water Reactor for Heat Transfer, Thermal-Mechanical Cyclic Stress Analysis, and Environmental Fatigue Life Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish; Soppet, William K.; Majumdar, Saurindranath; Natesan, Krishnamurti

    2015-12-15

    This paper discusses a system-level finite element model of a two-loop pressurized water reactor (PWR). Based on this model, system-level heat transfer analysis and subsequent sequentially coupled thermal-mechanical stress analysis were performed for typical thermal-mechanical fatigue cycles. The in-air fatigue lives of example components, such as the hot and cold legs, were estimated on the basis of stress analysis results, ASME in-air fatigue life estimation criteria, and fatigue design curves. Furthermore, environmental correction factors and associated PWR environment fatigue lives for the hot and cold legs were estimated by using estimated stress and strain histories and the approach described in US-NRC report: NUREG-6909.

  14. High oxygen consumption rates and scale loss indicate elevated aggressive behaviour at low rearing density, while elevated brain serotonergic activity suggest chronic stress at high rearing densities in farmed rainbow trout Oncorhynchus mykiss

    DEFF Research Database (Denmark)

    Laursen, Danielle Caroline; Silva, P.I.M.; Larsen, Bodil Katrine

    2013-01-01

    of a previous study,where levels of crowding where determined using the spatial distribution of fish in two-tank systems. An un-crowded low density of 25 kg m−3, the highest density accepted by the fish without showing indications of crowding stress of 80 kg m−3 as the intermediate density, and the highest...... density accepted by the fish showing indications of crowding stress of 140 kg m−3 as the high density were investigated. The aimof the present study was to examine the effect of being held at these densities on indicators of welfare. This was achieved through oxygen consumption measurements using...

  15. [Measurement of unemployment-related psychological stress: Validation of the Unemployment Stress (USS)].

    Science.gov (United States)

    Szabóné Kapuvári, Virág; Martos, Tamás

    2016-01-01

    Nowadays the theme of unemployment and the given answers of it are up to date questions in psychology. In spite of this fact, the psychological methods measuring this phenomenon are often missing. That is why the Unemployment Stress Scale (USS) is presented in this article. The aim of our study is to develop a scale called USS and test it's validity and reliability. There were 287 adult unemployed persons asked in this study. Besides the USS we used the Beck Depression Scale, the Spielberger Anxiety Scale (TRAIT), the Sense of Coherence Scale (Hungarian version) and the Rosenberg Self Esteem Scale. According to our results, USS has showed an excellent criterion and construct validity. A useful scale has been formed according to test-retest results. (Cronbach-alfa: 0.88 and 0.86 according to the samples). Moreover our scale has a strong correlation with the Spielberger Anxiety Scale (TRAIT) and the Beck Depression Scale. These chracteristics of the new scale proved that we fond a factor, independent from the self esteem and the sense of coherence, which represents the stress level in the situation of unemployment. This scale is a professional construction to measure stress contributed to unemployment. The USS can be a useful scale in clinical practice because after measuring with this scale we can protect the personality of the unemployed by representing the actual unemployment stress level. That is why professionals can help earlier in a crisis like this.

  16. Influence of Sub-grid-Scale Isentropic Transports on McRAS Evaluations using ARM-CART SCM Datasets

    Science.gov (United States)

    Sud, Y. C.; Walker, G. K.; Tao, W. K.

    2004-01-01

    In GCM-physics evaluations with the currently available ARM-CART SCM datasets, McRAS produced very similar character of near surface errors of simulated temperature and humidity containing typically warm and moist biases near the surface and cold and dry biases aloft. We argued it must have a common cause presumably rooted in the model physics. Lack of vertical adjustment of horizontal transport was thought to be a plausible source. Clearly, debarring such a freedom would force the incoming air to diffuse into the grid-cell which would naturally bias the surface air to become warm and moist while the upper air becomes cold and dry, a characteristic feature of McRAS biases. Since, the errors were significantly larger in the two winter cases that contain potentially more intense episodes of cold and warm advective transports, it further reaffirmed our argument and provided additional motivation to introduce the corrections. When the horizontal advective transports were suitably modified to allow rising and/or sinking following isentropic pathways of subgrid scale motions, the outcome was to cool and dry (or warm and moisten) the lower (or upper) levels. Ever, crude approximations invoking such a correction reduced the temperature and humidity biases considerably. The tests were performed on all the available ARM-CART SCM cases with consistent outcome. With the isentropic corrections implemented through two different numerical approximations, virtually similar benefits were derived further confirming the robustness of our inferences. These results suggest the need for insentropic advective transport adjustment in a GCM due to subgrid scale motions.

  17. Professional stress

    Directory of Open Access Journals (Sweden)

    Stanojević Dragana Z.

    2011-01-01

    Full Text Available Job stress is a line, for the person at work hired adverse physiological, psychological and behavioral reactions to situations in which job requirements are not in accordance with its capabilities, abilities and needs. Sources of stress at work are numerous. Personal factors: personality types have been most studied so far, environmental changes and demographic characteristics as well. Interpersonal stress inducing factors act and influence to the occurrence of many psychosomatic diseases. Psychosocial climate and relationships which are prevented or encouraged such as: cooperation and competition, trust and suspicion certainly affect to the appearance of professional stress. The way of leadership is very important. Organizational factors are the type of work, work time, noncompliance of the job, the introduction of new ethnologies, the conflict of personal roles, fear of job loss, bad physical conditions of working environment. The consequences of stress at work are numerous: at the cognitive level, the emotional level, the production plan, the health, plan reduces the immune system that cause a variety of psychosomatic illnesses and accidents at work.

  18. Changing stress levels through gaining information on stress

    Directory of Open Access Journals (Sweden)

    S.N. Madu

    2002-09-01

    Full Text Available Objective: The aim of this research was to find out the effect of the Information Phase of a Stress Management Program (SMP on the perceptions of participants about their stress levels. Method: A total sample of 100 workers (nursing staff, private business men and women, laboratory assistants, the protective services [foreman and security staff], as well as people in human resources departments took part in this study. All the participants were from the Northern and Gauteng Provinces in South Africa. The Combined Hassles and Uplifts Scale (Folkman & Lazarus, 1989 was used as an instrument to measure the perceived stress level of participants in a SMP. Result: A significant reduction in stress levels was achieved among those who received the Information Phase of the SMP only, as well as those who received the whole stress management techniques. There was no significant difference between the amount of reduction in perceived stress-levels achieved among those that received the Information Phase of the SMP only, compared to that of those who received the whole techniques. Conclusion: The authors conclude that where the resources are limited, only the information phase of a SMP may be given to desiring clients. That should help to save time and money spent on participating in SMPs. This should however not discourage the use of the whole SPM, where affordable. Keywords: Stress Management Programs, Information Phase, Perception, Stress Level.

  19. Towards an improved and more flexible representation of water stress in coupled photosynthesis-stomatal conductance models; implications for simulated land surface fluxes and variables at various spatiotemporal scales

    Science.gov (United States)

    Egea, G.; Verhoef, A.; Vidale, P. L.; Black, E.; Van den Hoof, C.

    2012-04-01

    Coupled photosynthesis-stomatal conductance (A-gs) models are commonly used in ecosystem models to represent the exchange rate of CO2 and H2O between vegetation and the atmosphere. The ways these models account for water stress differ greatly among modelling schemes. This study provides insight into the impact of contrasting model configurations of water stress on the simulated leaf-level values of net photosynthesis (A), stomatal conductance (gs), the functional relationship among them and their ratio, the intrinsic water use efficiency (A/gs), as soil dries. A simple, yet versatile, normalized soil moisture dependent function was used to account for the effects of water stress on gs, on mesophyll conductance (gm ) and on the biochemical capacity (Egea et al., 2011). Model output was compared to leaf-level values obtained from the literature. The sensitivity analyses emphasized the necessity to combine both stomatal and non-stomatal limitations of A in coupled A-gs models to accurately capture the observed functional relationships A vs. gs and A/gs vs. gs in response to drought. Accounting for water stress in coupled A-gs models by imposing either stomatal or biochemical limitations of A, as commonly practiced in most ecosystem models, failed to reproduce the observed functional relationship between key leaf gas exchange attributes. A quantitative limitation analysis revealed that the general pattern of C3 photosynthetic response to water stress can be represented in coupled A-gs models by imposing the highest limitation strength to mesophyll conductance, then to stomatal conductance and finally to the biochemical capacity. This more realistic representation of soil water stress on the simulated leaf-level values of A and gs was embedded in the JULES (Joint UK Land Environment Simulator; Best et al., 2011), model and tested for a number of vegetation types, for which driving and flux verification data were available. These simulations provide an insight into the

  20. What Is Stress Management?

    Science.gov (United States)

    ... Workplace Food and Beverage Toolkit What Is Stress Management? Updated:Jul 7,2016 What is Stress Management? ... FAQs About Stress Last reviewed - 6/2014 Stress Management • Home • How Does Stress Affect You? Introduction FAQs ...

  1. Stress and your health

    Science.gov (United States)

    Anxiety; Feeling uptight; Stress; Tension; Jitters; Apprehension ... Stress is a normal feeling. There are two main types of stress: Acute stress. This is short-term stress that goes away quickly. You feel ...

  2. Incorporating channel geometric uncertainty into a regional scale flood inundation model

    Science.gov (United States)

    Neal, Jeffrey; Odoni, Nick; Trigg, Mark; Freer, Jim; Bates, Paul

    2013-04-01

    Models that simulate the dynamics of river and floodplain water surface elevations over large regions have a wide range of applications including regional scale flood risk estimation and simulating wetland inundation dynamics, while potential emerging applications include estimating river discharge from level observations as part of a data assimilation system. The river routing schemes used by global land surface models are often relatively simple in that they are based on wave speed, kinematic and diffusive physics. However, as the research on large scale river modelling matures, approaches are being developed that resemble scaled-up versions of the hydrodynamic models traditionally applied to rivers at the reach scale. These developments are not surprising given that such models can be significantly more accurate than traditional routing schemes at simulating water surface elevation. This presentation builds on the work of Neal et al. (2012) who adapted a reach scale dynamic flood inundation model for large scale application with the addition of a sub-grid parameterisation for channel flow. The scheme was shown to be numerically stable and scalable, with the aid of some simple test cases, before it was applied to an 800 km reach of the River Niger that includes the complex waterways and lakes of the Niger Inland Delta in Mali. However, the model was significantly less accurate at low to moderate flows than at high flow due, in part, to assuming that the channel geometry was rectangular. Furthermore, this made it difficult to calibrate channel parameters with water levels during typical flow conditions. This presentation will describe an extension of this sub-grid model that allows the channel shape to be defined as an exponent of width, along with a regression based approach to approximate the wetted perimeter length for the new geometry. By treating the geometry in this way uncertainty in the channel shape can be considered as a model parameter, which for the

  3. Scaling down

    Directory of Open Access Journals (Sweden)

    Ronald L Breiger

    2015-11-01

    Full Text Available While “scaling up” is a lively topic in network science and Big Data analysis today, my purpose in this essay is to articulate an alternative problem, that of “scaling down,” which I believe will also require increased attention in coming years. “Scaling down” is the problem of how macro-level features of Big Data affect, shape, and evoke lower-level features and processes. I identify four aspects of this problem: the extent to which findings from studies of Facebook and other Big-Data platforms apply to human behavior at the scale of church suppers and department politics where we spend much of our lives; the extent to which the mathematics of scaling might be consistent with behavioral principles, moving beyond a “universal” theory of networks to the study of variation within and between networks; and how a large social field, including its history and culture, shapes the typical representations, interactions, and strategies at local levels in a text or social network.

  4. Mechanism for salt scaling

    Science.gov (United States)

    Valenza, John J., II

    Salt scaling is superficial damage caused by freezing a saline solution on the surface of a cementitious body. The damage consists of the removal of small chips or flakes of binder. The discovery of this phenomenon in the early 1950's prompted hundreds of experimental studies, which clearly elucidated the characteristics of this damage. In particular it was shown that a pessimum salt concentration exists, where a moderate salt concentration (˜3%) results in the most damage. Despite the numerous studies, the mechanism responsible for salt scaling has not been identified. In this work it is shown that salt scaling is a result of the large thermal expansion mismatch between ice and the cementitious body, and that the mechanism responsible for damage is analogous to glue-spalling. When ice forms on a cementitious body a bi-material composite is formed. The thermal expansion coefficient of the ice is ˜5 times that of the underlying body, so when the temperature of the composite is lowered below the melting point, the ice goes into tension. Once this stress exceeds the strength of the ice, cracks initiate in the ice and propagate into the surface of the cementitious body, removing a flake of material. The glue-spall mechanism accounts for all of the characteristics of salt scaling. In particular, a theoretical analysis is presented which shows that the pessimum concentration is a consequence of the effect of brine pockets on the mechanical properties of ice, and that the damage morphology is accounted for by fracture mechanics. Finally, empirical evidence is presented that proves that the glue-small mechanism is the primary cause of salt scaling. The primary experimental tool used in this study is a novel warping experiment, where a pool of liquid is formed on top of a thin (˜3 mm) plate of cement paste. Stresses in the plate, including thermal expansion mismatch, result in warping of the plate, which is easily detected. This technique revealed the existence of

  5. Stress Analysis

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    The following types of forces contribute to the stresses in a Dolos in a pack exposed to waves: 1)Gravity forces Compaction forces (mainly due to settlements, gravity and flow forces) 2) Flow forces 3) Impact forces (impacts between moving concrete blocks)......The following types of forces contribute to the stresses in a Dolos in a pack exposed to waves: 1)Gravity forces Compaction forces (mainly due to settlements, gravity and flow forces) 2) Flow forces 3) Impact forces (impacts between moving concrete blocks)...

  6. Scaling Rules!

    Science.gov (United States)

    Malkinson, Dan; Wittenberg, Lea

    2015-04-01

    Scaling is a fundamental issue in any spatially or temporally hierarchical system. Defining domains and identifying the boundaries of the hierarchical levels may be a challenging task. Hierarchical systems may be broadly classified to two categories: compartmental and continuous ones. Examples of compartmental systems include: governments, companies, computerized networks, biological taxonomy and others. In such systems the compartments, and hence the various levels and their constituents are easily delineated. In contrast, in continuous systems, such as geomorphological, ecological or climatological ones, detecting the boundaries of the various levels may be difficult. We propose that in continuous hierarchical systems a transition from one functional scale to another is associated with increased system variance. Crossing from a domain of one scale to the domain of another is associated with a transition or substitution of the dominant drivers operating in the system. Accordingly we suggest that crossing this boundary is characterized by increased variance, or a "variance leap", which stabilizes, until crossing to the next domain or hierarchy level. To assess this we compiled sediment yield data from studies conducted at various spatial scales and from different environments. The studies were partitioned to ones conducted in undisturbed environments, and those conducted in disturbed environments, specifically by wildfires. The studies were conducted in plots as small as 1 m2, and watersheds larger than 555000 ha. Regressing sediment yield against plot size, and incrementally calculating the variance in the systems, enabled us to detect domains where variance values were exceedingly high. We propose that at these domains scale-crossing occurs, and the systems transition from one hierarchical level to another. Moreover, the degree of the "variance leaps" characterizes the degree of connectivity among the scales.

  7. Is occupational stress associated with work engagement ?

    Science.gov (United States)

    Padula, Rosimeire Simprini; Chiavegato, Luciana Dias; Cabral, Cristina Maria Nunes; Almeid, Talita; Ortiz, Thais; Carregaro, Rodrigo Luiz

    2012-01-01

    The occupational stress is associated with dissatisfaction, excessive demand at work and personal factors. Those factors can reduce work performance and can predispose workers to various diseases. Workers' health may be protected if there is encouragement to face challenges, which may lessen the impact on psychological and somatic stress and thus have greater personal and professional satisfaction. The aim of this study was to evaluate the association between occupational stress and work engagement. Participated in this study 457 male and female workers of a metallurgical industry. Subjects answered personal data, and the Job Stress Scale and Utrecht Work Engagement Scale were applied. Results showed an association between occupational stress and work engagement (P=0,001). The way the individual deals with his frustrations, or rather the work engagement, is associated with the occupational stress.

  8. Nursing students’ perceived stress and influences in clinical performance

    OpenAIRE

    Laila Akhu-Zaheya; Insaf Shaban; Wejdan Khater

    2015-01-01

    Background: It is known that stress related to clinical training among nursing students could contribute to many physical and mental problems. However, little empirical evidence about the influence of stress in nurse students’ clinical performance Objective: The objective of this study was to assess the association between perceived stresses, stress related factors, and students’ clinical performance. Method: Using the perceived stress scale, 539 Jordanian nursing students from 2 publ...

  9. Syllable Structure and Word Stress in Hindi.

    Science.gov (United States)

    Shukla, Shaligram

    1990-01-01

    Discusses Hindi syllable structure from the point of view of the sonority scale and universal onset and coda conditions. The assignment of Hindi word stress based on the syllable structure is also examined. (GLR)

  10. Perceived stress in Saudi undergraduate medical students

    Directory of Open Access Journals (Sweden)

    Aesha Farheen Siddiqui

    2017-01-01

    Full Text Available This study aimed to assess the prevalence and magnitude of stress in Saudi undergraduate medical students and its associated socio-demographic factors using a cross-sectional design. It was conducted at King Khalid University Medical College during September-October 2016, including 267 students of both sexes and all study levels. Data was collected using an anonymous self administered questionnaire including socio-demographic information like participant details and family details, along with the Kessler -10 scale for measuring stress. Data analysis was carried out using SPSS 17.0. Results were de-scribed as frequencies, percentages, mean±SD. Independent samples t test and ANOVA were used to study the relationship of stress with various social and demographic factors. A mean stress score of 23.46±7.77 was observed. This is graded as mild stress according to Kessler scale classification. Forty four students, i.e. 16.5% reported perception of high stress, while 23.6% students perceived mild and 26.6% reported moderate stress. Students who perceived no stress comprised one third (33.3% of the study population. A significant relationship of female gender with stress was observed (p˂0.0001. It was concluded that most of the medical students undergo some degree of stress during their study period and female students have significantly more stress than their male counterparts. [J Med Allied Sci 2017; 7(1.000: 41-47

  11. Bacterial stress

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Bacterial stress. Physicochemical and chemical parameters: temperature, pressure, pH, salt concentration, oxygen, irradiation. Nutritional depravation: nutrient starvation, water shortage. Toxic compounds: Antibiotics, heavy metals, toxins, mutagens. Interactions with other cells: ...

  12. Gas-solid turbulent flow in a circulating fluidized bed riser: experimental and numerical study of mono-disperse particle systems

    NARCIS (Netherlands)

    He, Y.; Deen, N.G.; van Sint Annaland, M.; Kuipers, J.A.M.

    2009-01-01

    Numerical simulations were performed of a turbulent gas-particle multiphase flow in a circulating fluidized bed riser using a hard-sphere discrete particle model (DPM) for the particle phase and the Navier−Stokes equations for the gas phase, where the subgrid scale stresses (SGS) were modeled with

  13. Gas−Solid Turbulent Flow in a Circulating Fluidized Bed Riser: Numerical Study of Binary Particle Systems

    NARCIS (Netherlands)

    He, Y.; Deen, N.G.; van Sint Annaland, M.; Kuipers, J.A.M.

    2009-01-01

    Numerical simulations were performed of a turbulent gas-particle multiphase flow in a circulating fluidized bed riser using a hard-sphere discrete particle model (DPM) for the particle phase and the Navier−Stokes equations for the gas phase, where the subgrid scale stresses (SGS) were modeled with

  14. Gas-Solid Turbulent Flow in a Circulating Fluidized Bed Riser; Numerical Study of Binary Particle Mixtures

    NARCIS (Netherlands)

    He, Y; Deen, N.G.; van Sint Annaland, M.; Kuipers, J.A.M.

    2008-01-01

    A numerical simulation was performed on a turbulent gas-particle multi-phase flow in a circulating fluidized bed riser based on a hard-sphere discrete particle model (DPM) for the particle phase and the Navier-Stokes equations for the gas phase. The sub-grid scale stresses (SGS) were modeled with

  15. Relevance of approximate deconvolution for one-way coupled motion of inertial particles in LES of turbulent channel flow

    NARCIS (Netherlands)

    Jaszczur, Marck; Kuerten, Johannes G.M.; Salvetti, Maria-Vittoria; Geurts, Bernardus J.; Meyers, Johan; Sagaut, Pierre

    2011-01-01

    The Euler-Lagrange approach, based on Direct Numerical Simulation (DNS) and Large-Eddy Simulation (LES) for the fluid, is applied to particle-laden turbulent flow in a channel. Explicit subgrid modeling of the turbulent stresses is adopted, while the particle motion includes small turbulent scales

  16. Two-fluid sub-grid-scale viscosity in nonlinear simulation of ballooning modes in a heliotron device

    Science.gov (United States)

    Miura, H.; Hamba, F.; Ito, A.

    2017-07-01

    A large eddy simulation (LES) approach is introduced to enable the study of the nonlinear growth of ballooning modes in a heliotron-type device, by solving fully 3D two-fluid magnetohydrodynamic (MHD) equations numerically over a wide range of parameter space, keeping computational costs as low as possible. A model to substitute the influence of scales smaller than the grid size, at sub-grid scale (SGS), and at the scales larger than it—grid scale (GS)—has been developed for LES. The LESs of two-fluid MHD equations with SGS models have successfully reproduced the growth of the ballooning modes in the GS and nonlinear saturation. The numerical results show the importance of SGS effects on the GS components, or the effects of turbulent fluctuation at small scales in low-wavenumber unstable modes, over the course of the nonlinear saturation process. The results also show the usefulness of the LES approach in studying instability in a heliotron device. It is shown through a parameter survey over many SGS model coefficients that turbulent small-scale components in experiments can contribute to keeping the plasma core pressure from totally collapsing.

  17. Application of simplified models to CO2 migration and immobilization in large-scale geological systems

    KAUST Repository

    Gasda, Sarah E.

    2012-07-01

    Long-term stabilization of injected carbon dioxide (CO 2) is an essential component of risk management for geological carbon sequestration operations. However, migration and trapping phenomena are inherently complex, involving processes that act over multiple spatial and temporal scales. One example involves centimeter-scale density instabilities in the dissolved CO 2 region leading to large-scale convective mixing that can be a significant driver for CO 2 dissolution. Another example is the potentially important effect of capillary forces, in addition to buoyancy and viscous forces, on the evolution of mobile CO 2. Local capillary effects lead to a capillary transition zone, or capillary fringe, where both fluids are present in the mobile state. This small-scale effect may have a significant impact on large-scale plume migration as well as long-term residual and dissolution trapping. Computational models that can capture both large and small-scale effects are essential to predict the role of these processes on the long-term storage security of CO 2 sequestration operations. Conventional modeling tools are unable to resolve sufficiently all of these relevant processes when modeling CO 2 migration in large-scale geological systems. Herein, we present a vertically-integrated approach to CO 2 modeling that employs upscaled representations of these subgrid processes. We apply the model to the Johansen formation, a prospective site for sequestration of Norwegian CO 2 emissions, and explore the sensitivity of CO 2 migration and trapping to subscale physics. Model results show the relative importance of different physical processes in large-scale simulations. The ability of models such as this to capture the relevant physical processes at large spatial and temporal scales is important for prediction and analysis of CO 2 storage sites. © 2012 Elsevier Ltd.

  18. Parental Stress and Coping Inventory

    Science.gov (United States)

    Daire, Andrew P.; Gonzalez, Jennifer E.; O'Hare, Vanessa N.

    2017-01-01

    The Parental Stress and Coping Inventory was developed for mental health professionals serving low-income and low-resource parents. A sample of 1,567 parents completed a revised Family Adjustment Measure for the exploratory and confirmatory factor analyses conducted in this study. Findings resulted in three scales that explained 53% of the…

  19. Predictors of Stress in College Students

    OpenAIRE

    Saleh, Dalia; Camart, Nathalie; Romo, Lucia

    2017-01-01

    University students often face different stressful situations and preoccupations: the first contact with the university, the freedom of schedule organization, the selection of their master's degree, very selective fields, etc. The purpose of this study is to evaluate a model of vulnerability to stress in French college students. Stress factors were evaluated by a battery of six scales that was accessible online during 3 months. A total of 483 students, aged between 18 and 24 years (Mean = 20....

  20. Validation of an Australian Academic Stress Questionnaire

    Science.gov (United States)

    Lakaev, Natasha

    2009-01-01

    The aim of the study was to establish the Lakaev Academic Stress Response Scale (LASRS; Lakaev, 2006) as a valid and reliable measure of stress responses. The sample consisted of 375 Bond University students from several countries (142 Australia, 5 New Zealand, 68 United States, 8 Canada, 65 Asian, 66 Europe and 21 other) and from various levels…

  1. Investigating First Year Education Students' Stress Level

    Science.gov (United States)

    Geng, Gretchen; Midford, Richard

    2015-01-01

    This paper investigated the stress levels of first-year education students who undertake teaching practicum and theory units during their first year of teacher education program. First, 139 first-year and 143 other years' education students completed the PSS-10 scale, which measures perceived level of stress. Then, 147 first-year education…

  2. The general stress response of Bacillus subtilis

    NARCIS (Netherlands)

    van der Steen, J.B.

    2013-01-01

    The soil bacterium Bacillus subtilis responds to fluctuating conditions in its environment with a wide variety of stress responses. Apart from a series of specific responses and a series of large-scale developmental changes, B. subtilis also has a general stress response (GSR). The GSR is activated

  3. Kinetics of stress fibers

    Energy Technology Data Exchange (ETDEWEB)

    Stachowiak, Matthew R; O' Shaughnessy, Ben [Department of Chemical Engineering, Columbia University, New York, NY 10027 (United States)], E-mail: bo8@columbia.edu

    2008-02-15

    Stress fibers are contractile cytoskeletal structures, tensile actomyosin bundles which allow sensing and production of force, provide cells with adjustable rigidity and participate in various processes such as wound healing. The stress fiber is possibly the best characterized and most accessible multiprotein cellular contractile machine. Here we develop a quantitative model of the structure and relaxation kinetics of stress fibers. The principal experimentally known features are incorporated. The fiber has a periodic sarcomeric structure similar to muscle fibers with myosin motor proteins exerting contractile force by pulling on actin filaments. In addition the fiber contains the giant spring-like protein titin. Actin is continuously renewed by exchange with the cytosol leading to a turnover time of several minutes. In order that steady state be possible, turnover must be regulated. Our model invokes simple turnover and regulation mechanisms: actin association and dissociation occur at filament ends, while actin filament overlap above a certain threshold in the myosin-containing regions augments depolymerization rates. We use the model to study stress fiber relaxation kinetics after stimulation, as observed in a recent experimental study where some fiber regions were contractile and others expansive. We find that two distinct episodes ensue after stimulation: the turnover-overlap system relaxes rapidly in seconds, followed by the slow relaxation of sarcomere lengths in minutes. For parameter values as they have been characterized experimentally, we find the long time relaxation of sarcomere length is set by the rate at which actin filaments can grow or shrink in response to the forces exerted by the elastic and contractile elements. Consequently, the stress fiber relaxation time scales inversely with both titin spring constant and the intrinsic actin turnover rate. The model's predicted sarcomere velocities and contraction-expansion kinetics are in good

  4. Nuclear scales

    Energy Technology Data Exchange (ETDEWEB)

    Friar, J.L.

    1998-12-01

    Nuclear scales are discussed from the nuclear physics viewpoint. The conventional nuclear potential is characterized as a black box that interpolates nucleon-nucleon (NN) data, while being constrained by the best possible theoretical input. The latter consists of the longer-range parts of the NN force (e.g., OPEP, TPEP, the {pi}-{gamma} force), which can be calculated using chiral perturbation theory and gauged using modern phase-shift analyses. The shorter-range parts of the force are effectively parameterized by moments of the interaction that are independent of the details of the force model, in analogy to chiral perturbation theory. Results of GFMC calculations in light nuclei are interpreted in terms of fundamental scales, which are in good agreement with expectations from chiral effective field theories. Problems with spin-orbit-type observables are noted.

  5. Developing psychophysiological profiles for monitoring stress

    Science.gov (United States)

    Moldow, Roberta L.; Bergen, Michael T.; Belin, Kari; Bululu, Luba; Couso, Olivita; McLaughlin, Joselyn; Short, Kenneth R.; Servatius, Richard J.

    2006-05-01

    Training prepares first responders for disasters including terrorist attacks. To train effectively it should be as realistic as possible and elicit the stress response. We are developing a profile that will be a marker for intensity of stress as well as differentiate stress from exertion. We have monitored stress during several training scenarios for different groups including civilian SWAT teams and the military. In addition, we can monitor stress to exposure to nonlethal weapons. We have monitored stress during exposure to blunt impact using a paintball paradigm. We have measured salivary substances (such as cortisol and DHEA [markers for the hypothalamic-pituitary-adrenal axis]) and amylase [marker for the sympathetic branch of the autonomic nervous system], physiological parameters (such as activity and heart rate), and neuropsychological assessment tools (such as Borg's perceived exertion scale, Spielberger's STAI and Thayer's ADC). With these neuroendocrine, physiological and behavioral indices in hand, we are poised to examine stress induction in preparedness in trainees.

  6. When Feedback Fails: The Scaling and Saturation of Star Formation Efficiency

    Science.gov (United States)

    Y Grudic, Michael; Hopkins, Philip F.; Faucher-Giguere, Claude-Andre; Quataert, Eliot; Murray, Norman W.; Keres, Dusan

    2017-06-01

    We present a suite of 3D multi-physics MHD simulations following star formation in isolated turbulent molecular gas disks ranging from 5 to 500 parsecs in radius. These simulations are designed to survey the range of surface densities between those typical of Milky Way GMCs (˜100 M⊙pc-2) and extreme ULIRG environments (˜104M⊙pc-2) so as to map out the scaling of star formation efficiency (SFE) between these two regimes. The simulations include prescriptions for supernova, stellar wind, and radiative feedback, which we find to be essential in determining both the instantaneous (ɛff) and integrated (ɛint) star formation efficiencies. In all simulations, the gas disks form stars until a critical stellar mass has been reached and the remaining gas is blown out by stellar feedback. We find that surface density is the best predictor of ɛint of all of the gas cloud's global properties, as suggested by analytic force balance arguments from previous works. Furthermore, SFE eventually saturates to ˜1 at high surface density, with very good agreement across different spatial scales. We also find a roughly proportional relationship between ɛff and ɛint. These results have implications for star formation in galactic disks, the nature and fate of nuclear starbursts, and the formation of bound star clusters. The scaling of ɛff also contradicts star formation models in which ɛff˜1% universally, including popular subgrid models for galaxy simulations.

  7. Thermodynamics, maximum power, and the dynamics of preferential river flow structures at the continental scale

    Directory of Open Access Journals (Sweden)

    A. Kleidon

    2013-01-01

    Full Text Available The organization of drainage basins shows some reproducible phenomena, as exemplified by self-similar fractal river network structures and typical scaling laws, and these have been related to energetic optimization principles, such as minimization of stream power, minimum energy expenditure or maximum "access". Here we describe the organization and dynamics of drainage systems using thermodynamics, focusing on the generation, dissipation and transfer of free energy associated with river flow and sediment transport. We argue that the organization of drainage basins reflects the fundamental tendency of natural systems to deplete driving gradients as fast as possible through the maximization of free energy generation, thereby accelerating the dynamics of the system. This effectively results in the maximization of sediment export to deplete topographic gradients as fast as possible and potentially involves large-scale feedbacks to continental uplift. We illustrate this thermodynamic description with a set of three highly simplified models related to water and sediment flow and describe the mechanisms and feedbacks involved in the evolution and dynamics of the associated structures. We close by discussing how this thermodynamic perspective is consistent with previous approaches and the implications that such a thermodynamic description has for the understanding and prediction of sub-grid scale organization of drainage systems and preferential flow structures in general.

  8. Implications of scale-independent habitat specialization on persistence of a rare small mammal

    Directory of Open Access Journals (Sweden)

    Robert Klinger

    2015-01-01

    Full Text Available We assessed the habitat use patterns of the Amargosa vole Microtus californicus scirpensis, an endangered rodent endemic to wetland vegetation along a 3.5 km stretch of the Amargosa River in the Mojave Desert, USA. Our goals were to: (1 quantify the vole’s abundance, occupancy rates and habitat selection patterns along gradients of vegetation cover and spatial scale; (2 identify the processes that likely had the greatest influence on its habitat selection patterns. We trapped voles monthly in six 1 ha grids from January to May 2012 and measured habitat structure at subgrid (225m2 and trap (1m2 scales in winter and spring seasons. Regardless of scale, analyses of density, occupancy and vegetation structure consistently indicated that voles occurred in patches of bulrush (Schoenoplectus americanus; Cyperaceae where cover >50%. The majority of evidence indicates the vole’s habitat selectivity is likely driven by bulrush providing protection from intense predation. However, a combination of selective habitat use and limited movement resulted in a high proportion of apparently suitable bulrush patches being unoccupied. This suggests the Amargosa vole’s habitat selection behavior confers individual benefits but may not allow the overall population to persist in a changing environment.

  9. Implications of scale-independent habitat specialization on persistence of a rare small mammal

    Science.gov (United States)

    Cleaver, Michael; Klinger, Robert C.; Anderson, Steven T.; Maier, Paul A.; Clark, Jonathan

    2015-01-01

    We assessed the habitat use patterns of the Amargosa vole Microtus californicus scirpensis , an endangered rodent endemic to wetland vegetation along a 3.5 km stretch of the Amargosa River in the Mojave Desert, USA. Our goals were to: (1) quantify the vole’s abundance, occupancy rates and habitat selection patterns along gradients of vegetation cover and spatial scale; (2) identify the processes that likely had the greatest influence on its habitat selection patterns. We trapped voles monthly in six 1 ha grids from January to May 2012 and measured habitat structure at subgrid (View the MathML source225m2) and trap (View the MathML source1m2) scales in winter and spring seasons. Regardless of scale, analyses of density, occupancy and vegetation structure consistently indicated that voles occurred in patches of bulrush (Schoenoplectus americanus ; Cyperaceae) where cover >50%. The majority of evidence indicates the vole's habitat selectivity is likely driven by bulrush providing protection from intense predation. However, a combination of selective habitat use and limited movement resulted in a high proportion of apparently suitable bulrush patches being unoccupied. This suggests the Amargosa vole's habitat selection behavior confers individual benefits but may not allow the overall population to persist in a changing environment.

  10. Individual differences in delay discounting under acute stress: the role of trait perceived stress

    Directory of Open Access Journals (Sweden)

    Karolina M. Lempert

    2012-07-01

    Full Text Available Delay discounting refers to the reduction of the value of a future reward as the delay to that reward increases. The rate at which individuals discount future rewards varies as a function of both individual and contextual differences, and high delay discounting rates have been linked with problematic behaviors, including drug abuse and gambling. The current study investigated the effects of acute anticipatory stress on delay discounting, while considering two important factors: individual perceptions of stress and whether the stressful situation is future-focused or present-focused. Half of the participants experienced acute stress by anticipating giving a videotaped speech. This stress was either future-oriented (speech about future job or present-oriented (speech about physical appearance. They then performed a delay discounting task, in which they chose between smaller, immediate rewards and larger, delayed rewards. Their scores on the Perceived Stress Scale were also collected. The way in which one appraises a stressful situation interacts with acute stress to influence choices; under stressful conditions, delay discounting rate was highest in individuals with low perceived stress and lowest for individuals with high perceived stress. This result might be related to individual variation in reward responsiveness under stress. Furthermore, the time orientation of the task interacted with its stressfulness to affect the individual’s propensity to choose immediate rewards. These findings add to our understanding of the intermediary factors between stress and decision making.

  11. Levels of occupational stress and stressful activities for nurses working in emergency

    Directory of Open Access Journals (Sweden)

    José Ricardo Ferreira da Fonseca

    2014-12-01

    Full Text Available The study aimed to identify stress levels, areas and their activities identified as stressful by nurses working in the emergence in Manaus, AM, Brazil. It is an epidemiological, cross-sectional design, with 36 emergency nurses from December 2010 to January 2011. The Bianchi Stress Scale with 57 questions was used. The nurses were at risk for high levels of stress. The most stressful areas were the operation of the unit, conditions of work and personnel administration, and the most stressful activity was the request for equipment review and repair. The difference by Friedman test between the areas was significant (p <0.05, Dunn post-test significant (p <0.05 when compared by peers. The accumulation of management activities with the assistance activities can generate higher levels of stress, it is necessary to invest in improving the work environment and management support to minimize the stress experienced at work.

  12. Stress and your heart

    Science.gov (United States)

    Coronary heart disease - stress; Coronary artery disease - stress ... Your body responds to stress on many levels. First, it releases stress hormones that make you breathe faster. Your blood pressure goes up. Your muscles ...

  13. Stress and Mood

    Science.gov (United States)

    ... Relaxation Emotions & Relationships HealthyYouTXT Tools Home » Stress & Mood Stress & Mood Many people who go back to smoking ... story: Time Out Times 10 >> share What Causes Stress? Read full story: What Causes Stress? >> share The ...

  14. Repetitive Stress Injuries

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Repetitive Stress Injuries KidsHealth / For Teens / Repetitive Stress Injuries What's ... t had any problems since. What Are Repetitive Stress Injuries? Repetitive stress injuries (RSIs) are injuries that ...

  15. Stress Management: Positive Thinking

    Science.gov (United States)

    Healthy Lifestyle Stress management Positive thinking helps with stress management and can even improve your health. Practice overcoming negative self-talk ... with optimism is a key part of effective stress management. And effective stress management is associated with ...

  16. Relationship between general intelligence, emotional intelligence, stress levels and stress reactivity.

    Science.gov (United States)

    Singh, Yogesh; Sharma, Ratna

    2012-07-01

    Stressful life events and daily life stresses have both deleterious and cumulative effects on human body. In several studies, stress has been shown to affect various parameter of higher mental function like attention, concentration, learning and memory. Present study was designed to explore the relationship among GI level, EI level, psychological stress levels and acute stress reactivity in young normal healthy subjects. The study was conducted on thirty four healthy male student volunteers to study a) acute stress reactivity in subjects with varying levels of General Intelligence (GI) and Emotional Intelligence (EI) and b) correlation between GI, EI, acute stress and perceived stress. Baseline GI and EI and acute stress and perceived stress scores were measured by standard assessment scales. Using median value of GI and EI scores as cutoff values, subjects were categorized into four groups. Among different GI-EI groups, acute stress reactivity was similar but salivary Cortisol (especially post stressor level) and perceived stress level was a differentiating factor. High level of EI was associated inversely with acute and chronic perceived stress level. Significant correlation was found between acute and chronic perceived stress levels. Level of general intelligence showed no relation to acute or chronic stress levels as well as acute stress reactivity. The differences in various groups of GI and EI had no effect on the baseline and post stress performance on Sternberg memory test and all the three conditions of Stroop test. In conclusion emotional intelligence as an attribute is better suited to handle day to day acute stress and chronic perceived stress.

  17. [Psychosocial Stress, Stress Perception and Stress Management of Students of Social Work: a Quantitative Study].

    Science.gov (United States)

    Kriener, C; Schwertfeger, A; Deimel, D; Köhler, T

    2018-02-01

    In this quantitative study, data on 746 students of social work were collected regarding their current sense of stress, experience of psychosocial drain as well as their use of specific coping strategies. The Perceived Stress Scale (PSS) and the Trier Inventory of Chronic Stress (TICS) were used. The results show that one out of 3 students suffer from a lot of to extreme stress. One-fourth of the students report feeling overworked and socially overburdened. More than half of the students are exposed to psychosocial drain as a consequence of past events in their biography (e. g. death or mental illness of a close relative). Despite these obvious burdens, only one-fourth made use of professional aid or counseling. Students who are primarily using functional coping strategies have a lower sensibility to stress and feel less overworked than students primarily using dysfunctional coping strategies. In the university setting, the theoretically and empirically sound knowledge based on this report can be used profitably: The increasing implementation of seminars on coping with stress at universities itself suggests that learning and utilizing functional coping strategies can contribute to a reduction of stress and strain among students. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Perceived Stress in Young Carers: Development of a Measure

    Science.gov (United States)

    Early, Louise; Cushway, Delia; Cassidy, Tony

    2006-01-01

    We report the development of a 5-factor, 31-item, "Young Carers Perceived Stress Scale" (YCPSS) from an initial 50-item pool. The scale was developed and tested on 108 young carers aged between 12-18 years, and acceptable Cronbach Alpha values were obtained for the individual factors and the overall scale. In addition, both the overall scale and…

  19. A first large-scale flood inundation forecasting model

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, Guy J-P; Neal, Jeffrey C.; Voisin, Nathalie; Andreadis, Konstantinos M.; Pappenberger, Florian; Phanthuwongpakdee, Kay; Hall, Amanda C.; Bates, Paul D.

    2013-11-04

    At present continental to global scale flood forecasting focusses on predicting at a point discharge, with little attention to the detail and accuracy of local scale inundation predictions. Yet, inundation is actually the variable of interest and all flood impacts are inherently local in nature. This paper proposes a first large scale flood inundation ensemble forecasting model that uses best available data and modeling approaches in data scarce areas and at continental scales. The model was built for the Lower Zambezi River in southeast Africa to demonstrate current flood inundation forecasting capabilities in large data-scarce regions. The inundation model domain has a surface area of approximately 170k km2. ECMWF meteorological data were used to force the VIC (Variable Infiltration Capacity) macro-scale hydrological model which simulated and routed daily flows to the input boundary locations of the 2-D hydrodynamic model. Efficient hydrodynamic modeling over large areas still requires model grid resolutions that are typically larger than the width of many river channels that play a key a role in flood wave propagation. We therefore employed a novel sub-grid channel scheme to describe the river network in detail whilst at the same time representing the floodplain at an appropriate and efficient scale. The modeling system was first calibrated using water levels on the main channel from the ICESat (Ice, Cloud, and land Elevation Satellite) laser altimeter and then applied to predict the February 2007 Mozambique floods. Model evaluation showed that simulated flood edge cells were within a distance of about 1 km (one model resolution) compared to an observed flood edge of the event. Our study highlights that physically plausible parameter values and satisfactory performance can be achieved at spatial scales ranging from tens to several hundreds of thousands of km2 and at model grid resolutions up to several km2. However, initial model test runs in forecast mode

  20. Validation of the Antenatal Perceived Stress Inventory.

    Science.gov (United States)

    Razurel, Chantal; Kaiser, Barbara; Dupuis, Marc; Antonietti, Jean-Philippe; Citherlet, Catherine; Epiney, Manuella; Sellenet, Catherine

    2014-04-01

    This article presents the Antenatal Perceived Stress Inventory. The originality of this scale is to assess the impact of events experienced during pregnancy on the stress perceived by mothers. Scale validation was performed using data from 150 French-speaking nulliparous mothers and collected between 36 and 39 weeks of gestation (T1), and between 2 days (T2) and 6 weeks postpartum (T3). Factor analysis revealed a hierarchical three-factor structure that closely fit the data, including medical and obstetric risks/fetal health (F1), psychosocial changes (F2), and the prospect of childbirth (F3). The Antenatal Perceived Stress Inventory is a valid French prenatal stress scale with good psychometric properties.