Thermomechanical history effects on rigid PVC microstructure and impact properties

Rigid PVC microstructure strongly depends on processing conditions: under both shear and heat influence, gelation process occurs, and the resulting morphology can be characterized by the so‐called gelation level parameter. But thermomechanical history also affects several other features of the microstructure. In this work, two different aspects mainly related to (i) orientation and (ii) molecular mobility are pointed out, and their respective effects on poly(vinyl chloride) (PVC) impact properties are described. Charpy impact tests have been carried out on a typical extruded window profile formulation, evidencing a strong anisotropy effect in those extrudates. It turned out that modulated differential scanning calorimetry was able to evidence macromolecular orientation. Then, the effects of heat treatments on impact properties were investigated. Below the glassy transition temperature (T_g) of PVC, physical ageing results in a decrease of the impact performance, without affecting PVC anisotropy. The reason of this performance loss is the reduction of the molecular mobility, as evidenced by dynamical mechanical analysis experiments. After performing a heat treatment above T_g, another important decrease of the impact performance was observed. This decrease was attributed to (i) partial disorientation of the PVC macromolecular chains and (ii) reduction of the molecular mobility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2009–2017, 2007     

Cognitive therapy versus exposure and applied relaxation in social phobia: A randomized controlled trial.

A new cognitive therapy (CT) program was compared with an established behavioral treatment. Sixty-two patients meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) criteria for social phobia were randomly assigned to CT, exposure plus applied relaxation (EXP = AR), or wait-list (WAIT). CT and EXP = AR were superior to WAIT on all measures. On measures of social phobia, CT led to greater improvement than did EXP = AR. Percentages of patients who no longer met diagnostic criteria for social phobia at posttreatment-wait were as follows: 84% in CT, 42% in EXP = AR, and 0% in WAIT. At the 1-year follow-up, differences in outcome persisted. In addition, patients in EXP = AR were more likely to have sought additional treatment. Therapist effects were small and nonsignificant. CT appears to be superior to EXP = AR in the treatment of social phobia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Loneliness is a unique predictor of age-related differences in systolic blood pressure.

A population-based sample of Caucasians, African Americans, and Latino Americans, 50-68 years of age (M = 57.5), from Cook County, Illinois (N = 229), was tested to examine how loneliness and co-occurring psychosocial factors (depressive symptoms, perceived stress, social support, and hostility) were related to indices of cardiovascular and endocrine functioning. Extending prior research, the authors found that loneliness was associated with elevated systolic blood pressure (SBP) and age-related increases in SBP, net of demographic variables, health behavior variables, and the remaining psychosocial factors. Loneliness was not associated with differences in autonomic or endocrine functioning. Although the results are limited by the cross-sectional methods used, they are consistent with the hypothesis that cardiovascular disease contributes to increased morbidity and mortality among lonely individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Meta-Analytic Review of Prospective Memory and Aging.

A meta-analysis of prospective memory (PM) studies revealed that in laboratory settings younger participants outperform older participants on tests of both time- and event-based PM (rs=-.39 and -.34, respectively). Event-based PM tasks that impose higher levels of controlled strategic demand are associated with significantly larger age effects than event-based PM tasks that are supported by relatively more automatic processes (rs=-.40 vs. -.14, respectively). However, contrary to the prevailing view in the literature, retrospective memory as measured by free recall is associated with significantly greater age-related decline (r=-.52) than PM, and older participants perform substantially better than their younger counterparts in naturalistic PM studies (rs=.35 and .52 for event- and time-based PM, respectively). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of processing on adherence of a highly extended ham to its cooking bag

Highly extended cook-in-the-bag hams (65% brine/meat), representative of the products currently manufactured in Canada for mass distribution, were prepared using standard industrial equipment. Adherence between the cooked product and its packaging film was evaluated by measuring the force required to peel an excised band of film from the product surface. Overall, film-product adherence did not change after two weeks of refrigerated storage and was not affected by the extent of tumbling (from 360 to 4500 total turns) or by the cooking cycle (constant temperature of 74 °C, constant temperature of 84 °C, or stepwise temperature increase, until core temperature reaches 69 °C). Adherence was considerably reduced, however, when the extended muscles were finely homogenized prior to stuffing. A more detailed analysis of the results suggested that the occasional lack of proper film-product adherence observed in industry during the manufacture of highly extended hams cannot be due to mere deviations from the regular tumbling or cooking cycles. In addition, results point to the necessity of seeking alternative methods to quantify adherence between meat products and their cooking bags.     

Psychosocial mediation of fruit and vegetable consumption in the body and soul effectiveness trial.

In this study the authors examined psychosocial variables as mediators for fruit and vegetable (FV) intake in a clustered, randomized effectiveness trial conducted in African American churches. The study sample included 14 churches (8 intervention and 6 control) with 470 participants from the intervention churches and 285 participants from the control churches. The outcome of FV intake and the proposed mediators were measured at baseline and at 6-month follow-up. Structural equation modeling indicated that the intervention had direct effects on social support, self-efficacy, and autonomous motivation; these variables also had direct effects on FV intake. Applying the M. E. Sobel (1982) formula to test significant mediated effects, the authors confirmed that social support and self-efficacy were significant mediators but that autonomous motivation was not. Social support and self-efficacy partially mediated 20.9% of the total effect of the intervention on changes in FV intake. The results support the use of strategies to increase social support and self-efficacy in dietary intervention programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

émergence de la distinction personne-objet.

Investigated the emergence of the cognitive ability to distinguish persons and objects during the first few months of life. Thirty-eight infants took part in 2 experimental sessions, the first conducted at the age of 4 wks, the second at 10 wks. Each session consisted of 6 episodes in which the infant's mother, a stranger and a doll were presented under 2 conditions: "active" or "inactive." Infants' facial expressions, visual fixations and vocalizations were analyzed. Several differences were observed in infants behaviours towards the persons and the doll: the babies smiled more at their mother and at the stranger and vocalized more to people than to the doll. However, these differences were closely related to the activity of the stimuli presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

English language use as a risk factor for smoking initiation among Hispanic and Asian American adolescents: Evidence for mediation by tobacco-related beliefs and social norms.

Acculturation increases the risk of smoking among Hispanic and Asian American adolescents, but the underlying mechanisms are not understood. This study examined associations between English language use and smoking among 4,167 Hispanic and 2,836 Asian American adolescents in California. Potential mediators were assessed, including access to cigarettes, perceived consequences, friends' smoking, cigarette offers, refusal self-efficacy, and prevalence estimates of peer smoking. English language use was associated with increased risk of lifetime smoking in both groups. This association became nonsignificant after access, perceived consequences, friends' smoking, and offers were controlled for. The acculturation process (as indicated by English language use) may be associated with smoking-related psychosocial variables, which may lead to an increased risk of experimentation with smoking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)