881 research outputs found
Responding to natural disasters: Examining identity and prosociality in the context of a major earthquake
How does a major natural disaster relate to individualsâ orientation towards society? We collected repeated crossâsectional surveys before (n = 644) and after the 2010 Chile earthquake (n = 1,389) to examine levels of national identity, prosocial values, helping motivations, and prosocial behaviours in the context of such a calamitous societal event. Our research questions, derived from the literature on helping in times of crisis, considered how natural disasters may implicate identity and prosociality, as well as how identity, prosocial values, and motivations are linked to prosocial action after a disaster. Higher levels of national identity, helping motivations, and disasterârelated helping were found after the earthquake, suggesting that in the aftermath of a disaster, people unite under a common national identity and are motivated to take action related to disaster relief. National identity and prosocial values were closely linked to helping after the earthquake, but specific helping motivations rarely predicted prosocial behaviours. Additionally, proximity to the epicentre was related to higher levels of national identity and participation in reconstruction efforts. These findings contribute to our understanding of people's responses to natural disasters and suggest ways of encouraging prosocial behaviour in the aftermath of unexpected tragic events
Impact onto an ice floe
The unsteady problem of a rigid body impact onto a floating plate is studied. Both the plate and the water are at rest before impact. The plate motion is caused by the impact force transmitted to the plate through an elastic layer with viscous damping on the top of the plate. The hydrodynamic force is calculated by using the second-order model of plate impact by Iafrati and Korobkin (2011). The present study is concerned with the deceleration experienced by a rigid body during its collision with a floating object. The problem is studied also by a fully-nonlinear computational-fluid-dynamics method. The elastic layer is treated with a moving body-fitted grid, the impacting body with an immersed boundary method, and a discrete-element method is used for the contact-force model. The presence of the elastic layer between the impacting bod- ies may lead to multiple bouncing of them, if the bodies are relatively light, before their interaction is settled and they continue to penetrate together into the water. The present study is motivated by ship slamming in icy waters, and by the effect of ice conditions on conventional free-fall lifeboats
Hydrodynamic forces in water exit problems
The three-dimensional steady problem of an elongated smooth body moving along the water free surface at a constant speed is considered within the 2D+T approximation. The corresponding unsteady two-dimensional problem describes both the water entry and the subsequent exit of a smooth contour from the water. The shape of the contour varies in time. The present paper is concerned with the exit stage. The draft of the body is small compared with the body length and beam. The hydrodynamic loads during the entry stage are evaluated by the original Wagner model of water impact. The linearized exit model (Korobkin, 2013) is generalized to account for time-dependent acceleration of the body and the body shape which also varies in time. The integral equation with respect to the size of the wetted area of the body is solved numerically. The theoretical predictions of the hydrodynamic forces acting on the body during its exit from the liquid are compared with the numerical results obtained by solving the Navier-Stokes equations. A simplified model of water exit with the body shape approximated by a parabolic contour with a time-dependent radius of curvature is proposed and validated. It is shown that the linearized water-exit model with non-linear correction terms predicts reasonably well the hydrodynamic loads
Wedge impact with the influence of ice
This work presents a canonical study on a wedge entering water near a single piece of ice using computational-fluid-dynamics (CFD) and a Wagner-type theoretical model with corrections for non-linear effects. Calculations for a series of conditions with ice of different sizes and locations relative to the wedge are conducted. The hydrodynamic force due to impact, the pressure distribution on the wedge surface, and the pile-up phenomenon are examined to study the role of ice in the impact process. The theoretical model is shown to be accurate and can serve as a useful method to assess slamming loads under the influence of ice. It is shown that even for the case of a small piece of ice, the slamming force on the wedge can increase by 30%
The impact of changing attitudes, norms, and self-efficacy on health-related intentions and behavior: a meta-analysis
Objective: Several health behavior theories converge on the hypothesis that attitudes, norms, and self-efficacy are important determinants of intentions and behavior. Yet inferences regarding the relation between these cognitions and intention or behavior rest largely on correlational data that preclude causal inferences. To determine whether changing attitudes, norms, or self-efficacy leads to changes in intentions and behavior, investigators need to randomly assign participants to a treatment that significantly increases the respective cognition relative to a control condition, and test for differences in subsequent intentions or behavior. The present review analyzed findings from 204 experimental tests that met these criteria.
Methods: Studies were located using computerized searches and informal sources and meta-analyzed using STATA Version 11.
Results: Experimentally induced changes in attitudes, norms, and self-efficacy all led to medium-sized changes in intention (d+ = .48, .49, and .51, respectively), and engendered small to medium-sized changes in behavior (attitudes-d+ = .38; norms-d+ = .36; self-efficacy-d+ = .47). These effect sizes generally were not qualified by the moderator variables examined (e.g., study quality, theoretical basis of the intervention, methodological characteristics, features of the targeted behavior), although effects were larger for interventions designed to increase (vs. decrease) behavioral performance.
Conclusion: The present review lends novel, experimental support for key predictions from health behavior theories, and demonstrates that interventions that modify attitudes, norms, and self-efficacy are effective in promoting health behavior change
Maternal nutrient restriction in Guinea pigs leads to fetal growth restriction with evidence for chronic hypoxia
BackgroundWe determined whether maternal nutrient restriction (MNR) in Guinea pigs leading to fetal growth restriction (FGR) impacts markers for tissue hypoxia, implicating a mechanistic role for chronic hypoxia.MethodsGuinea pigs were fed ad libitum (Control) or 70% of the control diet before pregnancy, switching to 90% at mid-pregnancy (MNR). Near term, hypoxyprobe-1 (HP-1), a marker of tissue hypoxia, was injected into pregnant sows. Fetuses were then necropsied and liver, kidney, and placental tissues were processed for erythropoietin (EPO), EPO-receptor (EPOR), and vascular endothelial growth factor (VEGF) protein levels, and for HP-1 immunoreactivity (IR).ResultsFGR-MNR fetuses were 36% smaller with asymmetrical growth restriction compared to controls. EPO and VEGF protein levels were increased in the female FGR-MNR fetuses, providing support for hypoxic stimulus and linkage to increased erythropoiesis, but not in the male FGR-MNR fetuses, possibly reflecting a weaker link between oxygenation and erythropoiesis. HP-1 IR was increased in the liver and kidneys of both male and female FGR-MNR fetuses as an index of local tissue hypoxia, but with no changes in the placenta.ConclusionChronic hypoxia is likely to be an important signaling mechanism for the decreased fetal growth seen with maternal undernutrition and appears to be post-placental in nature
Optimization of the design of superconducting inhomogeneous nanowires
We study optimization of superconducting properties of inhomogeneous
nanowires. The main goal of this research is to find an optimized geometry that
allows one to maximize the desired property of superconductors, such as the
maximum value of local superconducting gap or total condensation energy. We
consider axially symmetric design of multi-layered nanowires with possibility
to adjust and change the layers thickness. We use numerical solution of the
Bogoliubov-de Gennes equations to obtain the local superconducting gap for
different arrangements of the inhomogeneous structures. The value of the
optimized properties can be up to 300% greater compared to a non-optimized
geometry. The optimized configuration of multilayers strongly depends on the
desired property one wants to optimize and on the number of layers in the
nanowire.Comment: Published in J. Phys.: Condens. Matter 20, 195204 (2008
Tactics for Transforming the Housing Structure, New Housing Models Incision of the City, Connecting the Urban Fragments of the City of Skopje
Josephson effect in superconducting constrictions with hybrid SF electrodes: peculiar properties determined by the misorientation of magnetizations
Josephson current in SFcFS junctions with arbitrary transparency of the
constriction (c) is investigated. The emphasis is done on the analysis of the
supercurrent dependencies on the misorientation angle between the
in-plane magnetizations of diffusive ferromagnetic layers (F). It is found that
the current-phase relation may be radically modified with the variation: the harmonic vanishes for definite value of
provided for identical orientation of the magnetizations () the junction is in the state. The Josephson current may exhibit a
nonmonotonic dependence on the misorientation angle both for realization of and state at . We also analyze the effect of exchange
field induced enhancement of the critical current which may occur in definite
range of .Comment: 7 pages, 5 figures, submitted to JETP Letter
Geological, multispectral, and meteorological imaging results from the Mars 2020 Perseverance rover in Jezero crater
Perseveranceâs Mastcam-Z instrument provides high-resolution stereo and multispectral images with a unique combination of spatial resolution, spatial coverage, and wavelength coverage along the roverâs traverse in Jezero crater, Mars. Images reveal rocks consistent with an igneous (including volcanic and/or volcaniclastic) and/or impactite origin and limited aqueous alteration, including polygonally fractured rocks with weathered coatings; massive boulder-forming bedrock consisting of mafic silicates, ferric oxides, and/or iron-bearing alteration minerals; and coarsely layered outcrops dominated by olivine. Pyroxene dominates the iron-bearing mineralogy in the fine-grained regolith, while olivine dominates the coarse-grained regolith. Solar and atmospheric imaging observations show significant intra- and intersol variations in dust optical depth and water ice clouds, as well as unique examples of boundary layer vortex action from both natural (dust devil) and Ingenuity helicopterâinduced dust lifting. High-resolution stereo imaging also provides geologic context for rover operations, other instrument observations, and sample selection, characterization, and confirmation
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