Use of a matrix converter to enhance the sensorless control of a surface-mount permanent-magnet AC motor at zero and low frequency

This paper addresses the use of a matrix converter (MC) with high-frequency voltage injection for zero- and low-speed sensorless control of surface mount permanent magnet alternating current motors. This paper also proposes a dual compensation technique that can practically eliminate zero-current-crossing distortions in MCs, discusses the effect of such distortions on sensorless control using injection techniques, and presents experimental results that illustrate the enhanced low-speed sensorless performance that can be obtained from exploiting the effective linearity of the MC operation.     

Relation between sexual abuse in childhood and adult depression: case-control study

OBJECTIVE: To examine the association between sexual abuse in childhood and adult depression in women. DESIGN: Two stage, case detection and case identification design, using the 30-item general health questionnaire and the Beck depression inventory for screening and the affective items relating to current functioning on the schizophrenia and affective disorders schedule to identify depressed cases. Details of sexual abuse in childhood were elicited retrospectively by semistructured interview, and social problems by the social problems questionnaire. SETTING: Three general practices, in middle class suburban, deprived inner city, and rural areas. SUBJECTS: 1189 women were screened and 237 subsequently interviewed; 132 were depressed. RESULTS: 49 (37%) of the depressed interviews and 24 (23%) of the non-depressed interviews reported experience of sexual abuse when they were aged under 16 years. A positive association existed between the more severe abuse and depression--all those who had experienced penetration were depressed as adults. A relation was also found between sexual abuse in childhood and sexual problems, housing problems, and problems with their children at school. CONCLUSION: A positive association between child sexual abuse and depression was confirmed, but this was confined to more severe abuse (penetration or attempted penetration).     

Online class size, note reading, note writing and collaborative discourse

Researchers have long recognized class size as affecting students?? performance in face-to-face contexts. However, few studies have examined the effects of class size on exact reading and writing loads in online graduate-level courses. This mixed-methods study examined relationships among class size, note reading, note writing, and collaborative discourse by analyzing tracking logs from 25 graduate-level online courses (25 instructors and 341 students) and interviews with 10 instructors and 12 graduate students. The quantitative and qualitative data analyses were designed to complement each other. The findings from this study point to class size as a major factor affecting note reading and writing loads in online graduate-level courses. Class size was found positively correlated with total number of notes students and instructors read and wrote, but negatively correlated with the percentage of notes students read, their note size and note grade level score. In larger classes, participants were more likely to experience information overload and students were more selective in reading notes. The data also suggest that the overload effects of large classes can be minimized by dividing students into small groups for discussion purposes. Interviewees felt that the use of small groups in large classes benefited their collaborative discussions. Findings suggested 13 to 15 as an optimal class size. The paper concludes with a list of pedagogical recommendations and suggestions for new multimedia software features to enhance collaborative learning in online classes.     

The examination of myofascial face pain and its relationship to psychological distress among women.

In this study, 110 female myofascial face pain patients were assessed monthly for 10 months on measures of pain, distress, and stressful life events. D. A. Kenny and A. J. Zautra's (1995) structural equation model for examining the separate trait, state, and error components of the variables was used to analyze the data. Both pain and distress had sizable trait variance, and the trait components were correlated. The 2 variables also showed sizable state variance, and the states of pain covaried with states of distress. A significant time-lagged relationship between the 2 variables was found: Increases in distress led to elevations in pain 1 mo later. Stressful life events arising from major social roles were also associated with greater distress, but not pain. Illness events unrelated to the pain syndrome were associated with both pain and distress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Leadership Behavior and Subordinate Well-Being.

The authors used a longitudinal design to investigate the relation between leadership behavior and the well-being of subordinates. Well-being is conceptualized as people's feelings about themselves and the settings in which they live and work. Staff members (N = 562) of 2 Community Trusts participated 4 times in a 14-month period. Five models were formulated to answer 2 questions: What is the most likely direction of the relation between leadership and well-being, and what is the time frame of this relation? The model with the best fit suggested that leadership behavior and subordinate responses are linked in a feedback loop. Leadership behavior at Time 1 influenced leadership behavior at Time 4. Subordinate well-being at Time 2 synchronously influenced leadership behavior at Time 2. Leadership behavior at Time 4 synchronously influenced subordinate well-being at Time 4. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Knowing where and knowing what: a double dissociation

We report a double dissociation between visuo-spatial abilities and semantic knowledge (knowledge of the names and attributes of objects and people), in two brain-injured people with longstanding stable impairments, using a wide range of tests to explore the extent of the dissociation, MU, who has bilateral lesions of occipito-parietal cortex, shows severe spatial disorientation with relatively well-preserved semantic knowledge. He is contrasted with JBR, who has bilateral temporal lobe damage and shows severe semantic problems and no impairment on visuo-spatial tasks. Our findings thus demonstrate a double dissociation between the performance of semantic and spatial tasks by MU and JBR. This pattern is consistent with Ungerleider and Mishkin's (1982) neurophysiological hypothesis of separable cortical visual pathways; one which is specialised for spatial perception and follows a dorsal route from occipital to parietal lobes, and the other following a more ventral route from occipital to temporal lobes, whose target is semantic information needed in specifying what an object is.     

The existence of a fatigue syndrome after glandular fever

This prospective cohort study was designed to test whether a distinct fatigue syndrome existed after the onset of glandular fever. Two hundred and fifty primary care patients, with either glandular fever or an ordinary upper respiratory tract infection (URTI) were interviewed three times in the 6 months after the clinical onset of their infection. At each interview a standardized psychiatric interview was given and physical symptoms were assessed. There were 108 subjects with and Epstein-Barr virus (EBV) infection; 83 subjects had glandular fever not caused by EBV and 54 subjects had an ordinary URTI. Five subjects were excluded because they had no evidence of an infection. Principal components analyses of symptoms supported the existence of a fatigue syndrome, particularly in the two glandular fever groups. The addition of symptoms not elicited by the standard interviews gave the full syndrome. This included physical and mental fatigue, excessive sleep, psychomotor retardation, poor concentration, anhedonia, irritability, social withdrawal, emotional lability, and transient sore throat and neck gland swelling with pain. A fatigue syndrome probably exists after glandular fever.     

A new analysis of life-span age trends in visual illusion.

Tested the magnitude of the over- and underestimated portions of the Ebbinghaus (Titchner circles) illusion in 688 Ss ranging in age from 5 to 70 yrs. Results indicate that the overestimated portion decreases while the underestimated portion yields increasing illusory distortion as a function of age. Both configurations produced nonlinear age trends. These results suggest that reports of inconsistent age trends in illusions may be the result of combining increasing and decreasing age functions found in some components of the same illusion configuration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual and memory search by process schizophrenics.

Compared the response times (RTs) of 20 process schizophrenics (10 paranoid and 10 nonparanoid) and 20 nonhospitalized controls (mean ages 39.2, 30.0, and 34.1 yrs, respectively) on a hybrid visual and memory search task in which Ss searched displays of up to 15 letters, reporting whether or not displays contained a target, which in different conditions was drawn from a memorized set of 1, 3, or 6 letters. RTs of all groups increased linearly with the product of the number in the memorized target set and the number of displayed letters. Although the intercepts and RTs of the schizophrenics (there were no paranoid–nonparanoid differences) exceeded those of controls, no group differences were found in slopes or in rates of increase in RT as a function of the number of memorized or displayed items. Results are interpreted in terms of a model proposed by W. Schneider and R. M. Shiffrin (1977), which indicates that process schizophrenics are retarded in processes associated with response production but not in a variety of processing stages involved in the comparison of displayed and memorized information. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)