A psychobiocultural model of orthostatic panic among Cambodian refugees: Flashbacks, catastrophic cognitions, and reduced orthostatic blood-pressure response.

This paper investigates cognitive and physiological precursors of orthostatic panic (OP), that is, panic upon standing, which is a key complaint among traumatized Cambodian refugees. Prior research links OP to hypotension (lower blood pressure) and catastrophic cognitions. A clinical sample of 102 Cambodian refugees were assessed for posttraumatic stress disorder (PTSD), recent OP attacks, and anticipatory anxiety before engaging in an orthostatic challenge (OC) task during which they were monitored for blood pressure. After the task, they were assessed for OC-induced culture-related catastrophic cognitions, flashbacks, and panic attacks. We found that participants with recent OP (n = 60) had more PTSD, greater anticipatory anxiety before the OC, a larger drop in systolic blood pressure during the OC, more OC-induced catastrophic cognitions and flashbacks, and more severe OC-induced panic attack symptoms. Regression models showed that the severity of OC-induced panic symptoms was predicted by the magnitude of SBP drop and mediated by more severe catastrophic cognitions and flashbacks. Implications of the findings for cross-cultural psychopathology research and the treatment of both panic and PTSD in Cambodian refugees are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Future directions in studies of trauma among ethnoracial and sexual minority samples: Commentary.

Objective: Studies examining psychological trauma or posttraumatic stress disorder (PTSD) in ethnoracial or sexual minority groups are relatively few. The Journal of Consulting and Clinical Psychology recently published 4 articles (Balsam, Lehavot, Beadnall, & Circo, 2010; Harrington, Crowther, & Shipherd, 2010; Lester, Resick, Young-Xu, & Artz, 2010; Marshall, Schell, & Miles, 2009) that examine trauma exposure and posttraumatic outcomes in ethnoracial and sexual minority samples. This commentary focuses on the overlap between traumatic stress and diversity studies in order to consider future areas in need of development. Method: Within the framework of a generalized overview of current trends in the study of traumatic stress, an assessment of the strengths and limitations of these 4 articles is provided. Populations and syndromes covered by the articles include ethnoracial differences in child maltreatment and adverse mental health outcomes among sexual minority participants, PTSD symptom elevations among Hispanic Americans, binge eating and the strong Black woman schema, and retention of African American female participants in cognitive behavioral psychotherapy trials for PTSD. Results: Recommendations to enhance culturally competent traumatic stress studies include increasing the examination of within-group cultural variability and key social, contextual, and cultural variables and constructs; examining the temporal sequencing of traumatic events and key transitions in sexual and ethnic minority identity development; and conducting prevention and treatment studies for those sexual minority children most at risk for maltreatment. Conclusions: By following these recommendations, the next generation of studies of traumatic stress studies will be enhanced. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correlations in rheological behavior between large amplitude oscillatory shear and steady shear flow of silica-filled star-shaped styrene-butadiene rubber compounds: Experiment and simulation

The large amplitude oscillatory shear (LAOS) and steady shear behavior of star-shaped SSBR/silica 60 phr (21 vol%) compounds with various filler surface areas was measured and simulated. An SBR gum and SBR compounds containing four different silicas with surface areas of 55, 135, 160, and 195 m²/g were utilized. Rheological behavior indicated clear correlation with surface area. LAOS tests showed an increase in dynamic moduli, shear stress, and higher order harmonic contributions with surface area. Elastic and viscous Lissajous figures showed significant distortion at intermediate and higher strain amplitudes. Additionally, ratios of third and fifth order stress harmonics to the first stress harmonic (I_3/1 and I_5/1 , respectively) showed a ''bump'' at intermediate strain amplitudes for the three highest surface area compounds. With regards to steady shear, all materials showed strong shear thinning behavior, and an increase in shear viscosity with surface area. The Cox-Merz rule was shown to be valid for the SBR gum but not for the filled compounds. However, the complex viscosity as a function of shear rate amplitude at various frequencies at high strain amplitudes and the steady shear viscosity as a function of shear rate coincided. This correlation, referred to as the Philippoff approach, has important ramifications for the rubber industry, providing quick data for predicting processing behavior. The Simhambhatla-Leonov model was successfully employed to simulate rheological behavior for the SBR gum and the lowest surface area silica compound, but the model yielded mixed results for the higher surface area silica compounds.     

LABORATORY CORROSION TESTS OF ROTARY LIMEKILN REFRACTORIES*

A modification of the Hugill, Ainsworth, and Green laboratory method for determining the corrosive action of lime on refractories was used to indicate the best refractory for rotary limekilns. An intermediate handmade refractory, two high alumina, two superduty, and two first-quality, stiff-mud refractories were tested. It was found that the depth of penetration of the lime attack decreases with an increase in alumina content of the refractory. Better resistance of the 70% aluminous refractories to slagging was indicated by the small-scale tests which were substantiated by plant-scale operation.     

Introduction to the special issue on trauma and ethnoracial diversity.

We are delighted to introduce this special issue of Psychological Trauma: Theory, Research, Practice, and Policy (PT: TRPP) devoted to the intersection of trauma and ethnoracial diversity. Given the growing ethnoracial diversity of the United States (U.S. Census Bureau, 2008) and inasmuch as Americans are becoming more involved with diverse cultures all over the world, trauma-oriented professionals are increasingly called upon to enhance and demonstrate their multicultural competence (American Psychological Association, 2003). Though there is already a robust literature examining trauma-related variables in different ethnic groups (see Pole, Gone, & Kulkarni, 2008 and Pole & Triffleman, 2008 for reviews), there is a need to both promote the advancement of such literature and augment its visibility. This special issue was conceived as one way to meet this need. We sought trauma-related studies that would: (a) illustrate differences among ethnoracial groups; (b) reveal the enormous variation within minority groups; and/or (c) draw attention to questions or issues that are of particular importance to minority groups. We found that the best examples of such studies were themselves diverse not only with respect to the ethnicity of their samples but also in terms of their methodology and focus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The psychophysiology of posttraumatic stress disorder: A meta-analysis.

This meta-analysis of 58 resting baseline studies, 25 startle studies, 17 standardized trauma cue studies, and 22 idiographic trauma cue studies compared adults with and without posttraumatic stress disorder (PTSD) on psychophysiological variables: facial electromyography (EMG), heart rate (HR), skin conductance (SC), and blood pressure. Significant weighted mean effects of PTSD were observed for HR (r = .18) and SC (r = .08) in resting baseline studies; eyeblink EMG (r = .13), HR (r = .23), and SC habituation slope (r = .21) in startle studies; HR (r = .27) in standardized trauma cue studies; and frontalis EMG (r = .21), corrugator EMG (r = .34), HR (r = .22), and SC (r = .19) in idiographic trauma cue studies. The most robust correlates of PTSD were SC habituation slope, facial EMG during idiographic trauma cues, and HR during all study types. Overall, the results support the view that PTSD is associated with elevated psychophysiology. However, the generalizability of these findings is limited by characteristics of the published literature, including its disproportionate focus on male veterans and neglect of potential PTSD subtypes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The nonlinear stress relaxation behavior after a step shear of star-shaped styrene-butadiene rubber filled with precipitated silica: Experiment and simulation

The nonlinear stress relaxation behavior after a step shear strain of star-shaped SSBR/silica compounds containing 21 vol% filler of various surface areas was measured and simulated using constitutive equations. A styrene-butadiene rubber (SBR) gum and SBR filled with silica having BET surface areas of 55, 135, 160, and 195 m²/g were used. Relaxation modulus behavior of the filled compounds was found to be dependent on surface area. Specifically, stress relaxation tests indicated that an increase in surface area led to increase in values of relaxation moduli in both the linear and nonlinear regimes. The time-dependent relaxation modulus exhibited a plateau at long times of relaxation in compounds containing silica of high surface area. Additionally, good time-strain superpositions were achieved for all samples at intermediate times of relaxation, and the strain-dependent damping function decreased with filler surface area. The constitutive equations proposed by Leonov and Simhambhatla and Leonov, modified to include multimodal relaxation of the particle network, were used to predict the time evolution of the relaxation modulus in the nonlinear regime for all samples. The simulations provided good results for the SBR gum for all tested strain levels. Also, in the compounds filled with silica, both models satisfactorily described the experimental observation in the nonlinear regime at low strain levels. However, at higher strain levels, due to a possible slip effect, the simulations overpredicted measured values of the relaxation moduli, thus leading to only qualitative predictions of the observed behavior. It is also possible that neither model accurately captured the floc rupture kinetics of these complex rubber compounds.     

METHOD OF MEASURING STRAINS BETWEEN GLAZES AND CERAMIC BODIES1

A new test was developed for comparing the strains existing between different glazes or other ceramic finishes and the bodies to which they are applied. By its use these strains may be so adjusted that the finishes will be in suflicient compression to prevent crazing from subsequent expansion of the body without causing initial shivering. The new test is particularly valuable because the measuremen & are made on combinations of glaze and body prepared and treated almost exactly like those intended for regular use and because of the simplicity and cheapness of the apparatus required. A modification of the test provides a comparison of the moisture expansions of different bodies.     

PHYSICAL PROPERTIES OF SOME HIGH-TEMPERATURE REFRACTORY COMPOSITIONS*

In the course of an investigation that involved a study of pyrochemical reactions, it was necessary to develop a refractory that could be used satisfactorily at temperatures in the range of 1800° to 2200°C. It was found that calcined magnesia (96%, MgO) or electrically fused magnesia (98% MgO) could be bonded adequately by mixing sized aggregates with 2.5%, by weight of calcined sea-water magnesia and wetting with a 24° Bé. solution of magnesium chloride Large shapes of these compositions fired at 1450°C. were satisfactory for use in the required temperature range. A small-scale study OF the properties of various refractory bodies showed that compositions containing relatively pure limestone or dolomite readily hydrated in water even after firing to 2100°C. and were unsuitable for refractory use. The addition of silica, alumina, zirconia, chromic oxide, or combinations of these oxides to dolomite or limestone resulted in a refractory stable against hydration. The inversion of zirconia was reduced appreciably by the addition of 5% magnesia. Bodies containing BaO·ZrO₂ and CaO·ZrO₂ were found to be stable after firing to 2100°C. with no inversion up to 1200°C. and with a coefficient of expansion less than that of electrically fused magnesia. Small- and large-scale tests of an MgO·Cr₂O₃ spinel composition showed this material to be highly refractory with a low coefficient of expansion; the compound, however, dissociates and loses Cr₂O₃ above 1700°C. While the small-scale tests disclosed a number of compositions which show promise as high-temperature refractories, their full evaluation for use on a large scale was not made.