A comparative study of Sr-doped LaMnO3 synthesised via solid-state reaction and sol–gel methods

ABSTRACT

This work deals with the synthesis of hole-doped La_1-xSr_xMnO₃ (x?=?0.25 and 0.33) perovskite via two different ways, namely a solid-state reaction method and a sol–gel process. Various properties of the samples have been investigated and compared by means of different techniques, namely X-ray diffraction (XRD), temperature-dependent resistivity measurements in the temperature range 25–300?K using a closed cycle refrigerator and vibrating sample magnetometry (VSM). All samples have orthorhombic crystal symmetry and an irregular variation in unit-cell volume with increase in Sr content. The average crystallite size was determined from the XRD data and found to lie in the range 19–22?nm. Metal–insulator transitions (MIT) were observed in all the samples via low-temperature electrical characterisations. The magnetic measurements confirm that the magnetisation does not saturate for the 25% Sr doped samples up to the available field of 10?kOe. The magnetic response also supports the interpretation of XRD and resistivity data. The obtained results are explained on the basis of double-exchange and super-exchange mechanisms.     

The Assessment and Diagnosis of Attention Deficit Hyperactivity Disorder in Adult Forensic Psychiatric Outpatients

The primary purpose of the present study was to examine the validity of commonly utilized ADHD rating scales within an adult forensic population. Participants were 120 patients assessed for dysfunctional anger and impulsive aggression at a hospital-based clinic. Two psychiatrists made independent diagnoses about the presence or absence of ADHD among individuals presenting with symptoms consistent with this disorder. Following the diagnoses, participants were assessed with multiple ADHD measures, including measures based on self-report, observer-report, or a computerized neuropsychological measure (IVA + Plus). With the exception of the IVA + Plus, the ADHD measures significantly differentiated individuals diagnosed with ADHD from individuals who were not so diagnosed. These measures also demonstrated good diagnostic utility via test specific parameters (sensitivity, specificity, positive predictive power, and negative predictive power). A sub-set of measures demonstrated particularly good classification accuracy, with high sensitivity (91 %) and good specificity (81 %). Implications of these findings for the effective assessment and diagnosis of ADHD in adult outpatient psychiatric settings are discussed.     

Measuring Situation Awareness in Virtual Environment-Based Training

We evaluated the efficacy of a computer-based situation awareness (SA) measurement system for training dismounted infantry SA in an urban terrain virtual reality (VR) simulation. Based on past research, we hypothesized that the SA measures would be sensitive to individual (squad leader) differences, and that the frequency of specific probes would reveal differences in critical SA requirements among scenarios. Three infantry squads performed multiple trials across two different scenarios. A confederate platoon leader posed probes to squad leaders during trials and experts made ratings afterward. Results revealed squad leaders had similar responses to probes, despite differences in combat experience. Analysis of probe frequency revealed different high priority SA elements and decisions for each scenario. The SA behavior and communication ratings revealed differences among squads, which trended with experience. Measures of SA were also consistent across the test scenario as a result of similar mission types and task difficulties. We discuss the implication of our findings for future research and theory within this area.     

Who’s got the Upper Hand? Hand Holding Behaviors Among Romantic Couples and Families

The hand holding behavior of romantic couples and family dyads (n?=?886) in public locations around Myrtle Beach, South Carolina was observed. Over 90 % of males in heterosexual romantic couples, parents in parent child pairs, and older siblings in child sibling pairs tended to place their hand on top when holding hands, displaying what we consider social dominance. Women holding hands with men in romantic relationships placed their hand under their partner’s hand, and women switched to have their hand on top when holding hands with a child. Results are discussed in relation to social dominance theory and social role theory, along with implications for equality among the sexes.     

The persistent impact of incidental experience

As we perform daily activities—driving to work, unlocking the office door, or grabbing a coffee cup—our actions seem automatic and preprogrammed. Nonetheless, routine, well-practiced behavior is continually modulated by incidental experience: In repetitive experimental tasks, recent (~4) trials reliably influence performance and action choice. Psychological theories downplay the significance of sequential effects, explaining them as rapidly decaying perturbations of behavior, with no long-term consequences. We challenged this traditional perspective in two experiments designed to probe the impact of more distant experience, finding evidence for effects spanning up to a thousand intermediate trials. We present a normative theory in which these persistent effects reflect optimal adaptation to a dynamic environment exhibiting varying rates of change. The theory predicts a heavy-tailed decaying influence of past experience, consistent with our data, and suggests that individual incidental experiences are catalogued in a temporally extended memory utilized in order to optimize subsequent behavior.     

Psychometric Properties of Bully,Fighting, and Victimization Scales Among Clinically Referred Youth

Bullying involvement is a multidimensional issue and a significant concern for school-aged youth. However, research on bullying involvement within clinical samples is limited. The present study examines the psychometric properties of the University of Illinois Bully, Fighting, and Victimization Scales among children and adolescents presenting for mood symptoms at a behavioral health outpatient clinic. Patients (n = 165) with an age range of 8–18 years were included in this investigation. Item frequencies, internal consistency, and construct validity were examined while confirmatory and exploratory factor analyses were conducted. Results showed that the scales were low to moderately correlated with each other. Internal consistencies were acceptable for the Bully (α = .70), Fighting (α = .84), and Victimization (α = .88) Scales. Exploratory factor analysis revealed clean three-factor solutions with items loading on their intended factors and with few cross-loadings. Fit of the confirmatory factor analysis was good when items were treated as ordinal and two items were allowed to cross-load on more than one factor. The University of Illinois Bully, Fighting, and Victimization Scales show utility for use with clinically referred youth.     

Reliability, factorial validity, and means on the Kuwait University Anxiety Scale: a UK university sample

A sample of 243 (114 men and 129 women) British university undergraduates (M age=22.5 yr., SD=5.8; M age=22.0 yr., SD=5.7, respectively) completed the English version of the Kuwait University Anxiety Scale. Principal components analysis with the use of parallel analysis and a scree test suggest that in the current sample the items form a single factor and show a coefficient alpha of .92, denoting high internal consistency. No significant mean difference was found by sex. By and large, the Kuwait University Anxiety Scale can be recommended for use in research among college students in the United Kingdom.     

Psychoendocrine and physical performance responses in male Tunisian rugby players during an international competitive season

The aim was to investigate a follow-up study based on hormonal, physical, and psychological parameters among rugby players who trained during a whole season interspersed with competitions on an international level. Fitness or reciprocally tiredness as well as competitive anxiety were evaluated, respectively, using the French Society for Sports Medicine (SFMS) and the sport competition anxiety test (SCAT) questionnaires. In this study, SFMS and SCAT scores increased respectively over the competitive season. The SFMS score revealed a state of relative tiredness at the end of the season, highlighted by a slight decrement in physical performances. The SCAT score changes are related to the competition context and therefore increased accordingly to the importance of the competition stake. We analyzed the corticotrope and the gonadotrope axis before (T(1)), and at the end of the national and international rugby season (T(2)). Training did not affect the resting salivary cortisol (Csal) levels, but induced a decrease in resting testosterone (Tsal) values, resulting in a dropped T/C ratio. Competition, in both periods (T(1)-T(2)), provoked a significant increase in Csal levels, but the Tsal responses depended on the match stake. Their concentrations increased when the competition generated an important stress and decreased when the psychological conditions remained relatively stable. SFMS is preferentially correlated with resting Csal levels and T/C values measured at 08:00 hr but not with Tsal. SCAT is highly correlated with competitive Csal and Tsal concentrations measured before and after the matches.     

Ethical challenges with the left ventricular assist device as a destination therapy

The left ventricular assist device was originally designed to be surgically implanted as a bridge to transplantation for patients with chronic end-stage heart failure. On the basis of the REMATCH trial, the US Food and Drug Administration and the US Centers for Medicare & Medicaid Services approved permanent implantation of the left ventricular assist device as a destination therapy in Medicare beneficiaries who are not candidates for heart transplantation. The use of the left ventricular assist device as a destination therapy raises certain ethical challenges. Left ventricular assist devices can prolong the survival of average recipients compared with optimal medical management of chronic end-stage heart failure. However, the overall quality of life can be adversely affected in some recipients because of serious infections, neurologic complications, and device malfunction. Left ventricular assist devices alter end-of-life trajectories. The caregivers of recipients may experience significant burden (e.g., poor physical health, depression, anxiety, and posttraumatic stress disorder) from destination therapy with left ventricular assist devices. There are also social and financial ramifications for recipients and their families. We advocate early utilization of a palliative care approach and outline prerequisite conditions so that consenting for the use of a left ventricular assist device as a destination therapy is a well informed process. These conditions include: (1) direct participation of a multidisciplinary care team, including palliative care specialists, (2) a concise plan of care for anticipated device-related complications, (3) careful surveillance and counseling for caregiver burden, (4) advance-care planning for anticipated end-of-life trajectories and timing of device deactivation, and (5) a plan to address the long-term financial burden on patients, families, and caregivers.     

Reducing assaults on an acute psychiatric unit using a token economy: a 2‐year follow‐up

Token economies are an effective way of changing various behaviors including acquiring new skills, reducing undesired behaviors, reducing aggression, increasing treatment compliance, and improving psychiatric unit management. This study examines the long‐term effect of a token economy on an acute care, inpatient psychiatric unit. The two years following the implementation of a unit based token economy are compared with the 12 months prior to implementation. The results show a significant reduction in total assaults as well as fewer staff injuries resulting in loss of time from work. Copyright © 2003 John Wiley & Sons, Ltd.