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Selected AbstractsCompetition and the Incentive to Produce High QualityECONOMICA, Issue 279 2003Rachel E. Kranton Previous literature indicates that, when quality is a choice variable, firms have an incentive to produce high quality to maintain their reputations with consumers. The strategic interaction among firms and competition for market share is not considered. This paper finds that, when firms compete for market share, perfect equilibria in which firms produce high-quality goods need not exist. Competition for customers can eliminate the price premium needed to induce firms to maintain a reputation for high-quality production. In this case, economists and policy analysts should pay greater attention to the interaction among firms and the institutions, such as professional associations, that structure interfirm relations when considering whether firms have an incentive to produce high-quality goods. [source] A Random Utility Model of Environmental EquityGROWTH AND CHANGE, Issue 1 2000Diane Hite Past attempts to uncover evidence that economically disadvantaged groups are unjustly exposed to environmental disamenities have failed to take into account self-selection behavior of individuals or groups of individuals. For instance, when choosing a place to live, households may be trading environmental quality for other housing, neighborhood, and location characteristics they care about. Previous literature on environmental justice has investigated location choice of polluting industries, but fails to account for consumer self-selection in housing markets. This paper thus focuses on location choice of individuals based on observed housing transactions. From the results of a random utility model, a test is proposed that incorporates the no-envy concept of economic equity. The results support a finding for environmental discrimination with respect to African American households, but do not support the hypothesis that poor households in general are unfairly exposed to environmental disamenities. [source] Investigation of quality of the parental relationship as a risk factor for subclinical bulimia nervosaINTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 4 2001Tracey D. Wade Abstract Objective Previous literature suggests a link between the quality of the parental relationship and disordered eating in offspring. We investigated the relationship between offspring pyschopathology and the parental relationship using a population-based twin registry that contained 766 complete twin pairs. Method We used reports of twin lifetime psychopathology from the twins and quality of parental relationship and parental lifetime psychopathology from both parents. Results Poorer quality of the marital relationship predicted the presence of subclinical bulimia nervosa (SBN) using both mother's (odds ratio [OR] = 0.83, 95% confidence interval [CI]: 0.71,0.97) and father's (OR = 0.78, 95% CI: 0.62,0.97) reports. It also predicted the presence of generalized anxiety disorder (GAD) and alcohol dependence. SBN was still strongly predicted by the marital relationship when parental psychopathology was included as a covariate. Discussion These results are supportive of the notion that a conflictual and distant marital relationship can, at least partially, act as an environmental risk factor for SBN. © 2001 by John Wiley & Sons, Inc. Int J Eat Disord 30: 389,400, 2001. [source] Service quality in hospital wards with different nursing organization: nurses' ratingsJOURNAL OF ADVANCED NURSING, Issue 2 2009Ingeborg S. Sjetne Abstract Title.,Service quality in hospital wards with different nursing organization: nurses' ratings. Aim., This paper is a report of a study to assess: (1) the relations between nursing organization models in hospital wards and nurses' perception of the quality of patient care and dimensions of the practice environment, and (2) if these relations were modified by variations in local conditions at the ward level. Background., Previous literature is inconclusive concerning what model of nursing organization maximizes the quality of nursing services. Method., A cross-sectional survey was carried out in a representative sample of Norwegian hospital wards in 2005. Intra-ward organization models were classified as: (1) Team leader (n = 30), characterized by extensive responsibilities for team leaders, (2) Primary nurse (n = 18), with extensive responsibilities for named nurses, and (3) Hybrid (n = 37), (1) and (2) combined. We prepared multilevel regression models using scales describing quality of patient care, learning climate, job satisfaction, and relationships with physicians as dependent variables. As independent variables, we used variables representing local ward conditions. Results., Eighty-seven wards and 1137 nurses (55% response rate) provided complete data. The ward level proportion of variance ranged from 0·10 (job satisfaction) to 0·22 (relationships with physicians). The univariate effect of organization models on quality ratings was not statistically significant. Introducing local ward conditions led to a statistically significant effect of primary nurse organization on relationships with physicians, and to a substantial proportional reduction in ward level variance, ranging from 32% (quality of patient care) to 24% (learning climate). Conclusion., Caution is needed about using service quality arguments when considering the possible benefits and drawbacks of different organizational models. [source] Mechanism of Repolarization Change During Initiation of Supraventricular TachycardiaJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2004YENN-JIANG LIN M.D. Introduction: Previous literature has documented the association between narrow QRS supraventricular tachycardia (SVT) and pronounced ST-T segment change. The aim of this study was to evaluate repolarization changes during SVT initiation and demonstrate the possible mechanism. Methods and Results: Fifty-one consecutive patients (20 men and 31 women; mean age 46.1 ± 16.4 years) with narrow QRS SVT (32 patients with AV nodal reentrant tachycardia and 19 patients with AV reentrant tachycardia) were included. We retrospectively analyzed the intracardiac recordings and ST-T segment changes on 12-lead surface ECGs during SVT initiation. Twenty-six (51%) patients developed ST segment repolarization changes during SVT initiation. Patients with shorter baseline sinus cycle length, shorter tachycardia cycle length, elevated systolic blood pressure before tachycardia induction, and greater reduction of systolic blood pressure had a higher incidence of repolarization changes. However, multivariate analysis showed that reduction of systolic blood pressure after SVT induction was the only independent predictor of repolarization changes. Furthermore, the maximal degree of ST segment depression during SVT correlated with the reduction of systolic blood pressure (r = 0.75, P < 0.001). Conclusion: Repolarization changes during SVT initiation were caused mainly by concurrent hemodynamic change after SVT initiation with abrupt cycle length shortening. [source] Exploring the perspective of midwives involved in offering serum screening for Down's syndrome in Northern IrelandJOURNAL OF CLINICAL NURSING, Issue 20 2009Jennifer McNeill Aims., To explore the perspective of midwives offering serum screening for Down's syndrome. Background., Previous literature has indicated that the offer and discussion of prenatal serum screening tests with women is complex, and health professionals may influence women's decisions to accept or decline screening. Midwives are usually the key professional to offer serum screening for Down's syndrome in the UK but their perspective is relatively neglected in the literature. Design., An explorative qualitative interview study with 15 midwives employed in a maternity unit in Northern Ireland involved in offering prenatal screening to pregnant women. Data were collected from 1 July 2005,31 October 2005. Methods., A focused ethnographic approach was used to explore the perspective of midwives. Results., Midwives reported difficulty in explaining the test to women and felt unable to provide the necessary information to adequately inform women within their appointment time. The test offered (the triple test) and potential pathway of subsequent care, were identified as sources of professional and personal conflict by midwives. The expectation that midwives would provide a universal offer of Down's syndrome serum screening but be unable to support women regarding termination of pregnancy also created dissonance. Conclusions., The feasibility of proceeding with a universal serum screening programme for Down's syndrome is questionable in countries which legally or culturally oppose termination of pregnancy. Professionals practising within environments such as this experience conflict in their role, which affects communication with women when discussing screening tests. Relevance to clinical practice., As midwives are often, the primary health professional providing information to women, it is important that midwives are key participants in ongoing planning and discussions about screening policy to ensure programmes are implemented successfully. [source] ORIGINAL ARTICLE: Comparison by crime type of juvenile delinquents on pornography exposure: The absence of relationships between exposure to pornography and sexual offense characteristics1JOURNAL OF FORENSIC NURSING, Issue 3 2010David L. Burton MSW Abstract Previous literature on pornography indicates that pornography use for men at risk for aggression may result in sexually aggressive behavior, but very little research has been reported on juvenile sexual abusers' exposure to pornography. The current study compared pornography exposure between male adolescent sexual abusers (n= 283) and male nonsexually offending delinquent youth (n= 170). Sexual abusers reported more pre- and post-10 (years of age) exposure to pornography than nonsexual abusers. Yet, for the sexual abusers, exposure is not correlated to the age at which the abusers started abusing, to their reported number of victims, or to sexual offense severity. The pre-10 exposure subscale was not related to the number of children the group sexually abused, and the forceful exposure subscale was not correlated with either arousal to rape or degree of force used by the youth. Finally, exposure was significantly correlated with all of the nonsexual crime scores in the study. Implications for forensic nursing are discussed. [source] Psychiatric diagnosis, intellectual disabilities and Diagnostic Criteria for Psychiatric Disorders for Use with Adults with Learning Disabilities/Mental Retardation (DC-LD)JOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 2003Sally-Ann Cooper Abstract Background Classification of psychopathology using operationalized diagnostic criteria is one component of psychiatric assessment. Previous literature has demonstrated that there are limitations in the International Classification of Diseases,10 (ICD-10) and the Diagnostic and Statistical Manual,IV (DSM-IV) when used with adults with intellectual disabilities. Methods A literature search using Medline, PsychLIT and hand searching of key journals identified the existing literature, which was reviewed by the Diagnostic Criteria for Psychiatric Disorders for Use with Adults with Learning Disabilities/Mental Retardation (DC-LD) Development Working Group. Key findings are integrated into this paper. This, together with expert consensus led to the development of DC-LD, a new psychiatric classificatory system devised specifically for use with adults with intellectual disabilities. The new diagnostic criteria and classification within DC-LD were piloted with 52 field investigators drawing on 709 clinical cases. Validity of DC-LD classification was measured by comparison between the criteria providing DC-LD diagnosis and the gold standard of learning disabilities psychiatric assessment. Results In 96.3% of cases, the DC-LD diagnosis was fully concordant with that of clinical opinion. The few discrepancies related to level of detail. Conclusion DC-LD accommodates the pathoplastic effect of intellectual disabilities on psychopathology. Its use will hopefully improve clinical practice and facilitate research, but further work to determine its usefulness and limitations is required. [source] The relationship between women's subjective and physiological sexual arousalPSYCHOPHYSIOLOGY, Issue 1 2005Alessandra H. Rellini Abstract Previous literature presents discordant results on the relationship between physiological and subjective sexual arousal in women. In this study, the use of hierarchical linear modeling (HLM) revealed a significant concordance between continuous measures of physiological and subjective sexual arousal as assessed during exposure to erotic stimuli in a laboratory setting. We propose that past studies that have found little or no association between the two measures may have been in part limited by the methodology and statistical analyses employed. [source] Asymmetric volatility of basis and the theory of storageTHE JOURNAL OF FUTURES MARKETS, Issue 4 2005Andre H. Gao The theory of storage states that the marginal convenience yield on inventory falls at a decreasing rate as inventory increases. Previous literature has tested this hypothesis using the so-called "direct test" approach, which employs a direct measurement of inventory levels, or the "indirect test" approach, which examines the relative variation of spot and futures prices and the relative variation of negative basis to positive basis as alternative proxies for inventory levels. The rationale behind the indirect test is based on the hypothesis that futures prices are less variable than spot prices when inventory is low, and have similar variability when inventory is high. The authors propose a "unified test" of the theory of storage that incorporates aspects of both direct and indirect tests in an ARMAX-asymmetric GARCH model framework. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:399,418, 2005 [source] Correlation of Optic Nerve Sheath Diameter with Direct Measurement of Intracranial PressureACADEMIC EMERGENCY MEDICINE, Issue 2 2008Heidi Harbison Kimberly MD Abstract Background:, Measurements of the optic nerve sheath diameter (ONSD) using bedside ultrasound (US) have been shown to correlate with clinical and radiologic signs and symptoms of increased intracranial pressure (ICP). Objectives:, Previous literature has identified 5 mm as the ONSD measurement above which patients exhibit either clinical or radiologic signs of elevated ICP. The goals of this study were to evaluate the association between ONSD and ICP and to validate the commonly used ONSD threshold of 5 mm using direct measurements of ICP as measured by ventriculostomy. Methods:, A prospective blinded observational study was performed using a convenience sample of adult patients in both the emergency department (ED) and the neurologic intensive care unit (ICU) who had invasive intracranial monitors placed as part of their clinical care. Ocular USs were performed with a 10,5 MHz linear probe. Emergency physicians (EPs) with previous ocular US experience performed ONSD measurements while blinded to the contemporaneous ICP reading obtained directly from invasive monitoring. The association between ONSD and ICP was assessed with the Spearman rank correlation coefficient, and a receiver operator characteristic (ROC) curve was created to determine the optimal ONSD cutoff to detect ICP > 20 cm H2O. Results:, Thirty-eight ocular USs were performed on 15 individual patients. Spearman rank correlation coefficient of ONSD and ICP was 0.59 (p < 0.0005) demonstrating a significant positive correlation. An ROC curve was created to assess the ability of ONSD to distinguish an abnormal ICP greater than 20 cm H2O. The area under the ROC curve was 0.93 (95% confidence interval [CI] = 0.84 to 0.99). Based on inspection of the ROC curve, ONSD > 5 mm performed well to detect ICP > 20 cm H2O with a sensitivity of 88% (95% CI = 47% to 99%) and specificity of 93% (95% CI = 78% to 99%). Conclusions:, Using an ROC curve the authors systematically confirmed the commonly used threshold of ONSD > 5 mm to detect ICP > 20 cm H2O. This study directly correlates ventriculostomy measurements of ICP with US ONSD measurements and provides further support for the use of ONSD measurements as a noninvasive test for elevated ICP. [source] Myocardial infarction following the combined recreational use of viagra® and cannabisCLINICAL CARDIOLOGY, Issue 3 2002Dr. A. L. McLeod M.D. Abstract Sildenafil citrate (Viagra®,Pfizer, Inc., New York, N.Y.) is widely prescribed as a treatment for male erectile dysfunction. It is metabolized predominantly by the cytochrome P450 3A4 hepatic microsomal isoenzyme and effects can, therefore, be potentiated by such inhibitors. The vasodilatory effects of Viagra necessitate caution in its use in patients with cardiovascular disease and it is contraindicated in patients receiving nitrates. Previous literature has drawn attention to Viagra use and myocardial infarction. This paper reports the case of a young man who presented with a myocardial infarction after taking Viagra in combination with cannabis, a known inhibitor of the cytochrome P450 3A4 isoenzyme. [source] IS CORPORATE R&D INVESTMENT IN HIGH-TECH SECTORS MORE EFFECTIVE?CONTEMPORARY ECONOMIC POLICY, Issue 3 2010RAQUEL ORTEGA-ARGILÉS This paper discusses the link between R&D and productivity across the European industrial and service sectors. The empirical analysis is based on both the European sectoral OECD data and on a unique micro-longitudinal database consisting of 532 top European R&D investors. The main conclusions are as follows. First, the R&D stock has a significant positive impact on labor productivity; this general result is largely consistent with previous literature in terms of the sign, the significance, and the magnitude of the estimated coefficients. More interestingly, both at sectoral and firm levels the R&D coefficient increases monotonically (both in significance and magnitude) when we move from the low-tech to the medium- and high-tech sectors. This outcome means that corporate R&D investment is more effective in the high-tech sectors and this may need to be taken into account when designing policy instruments (subsidies, fiscal incentives, etc.) in support of private R&D. However, R&D investment is not the sole source of productivity gains; technological change embodied in gross investment is of comparable importance on aggregate and is the main determinant of productivity increase in the low-tech sectors. Hence, an economic policy aiming to increase productivity in the low-tech sectors should support overall capital formation. [source] Factors predicting arrest for homeless persons receiving integrated residential treatment for co-occurring disordersCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 5 2009Blake Barrett Background,Homeless individuals are at increased risk for health and criminal justice problems. Aims,The aim of this study was to examine risk factors affecting arrest rates in a cohort of homeless people with co-occurring psychiatric and substance-abuse disorders. Methods,Baseline data were collected from 96 homeless individuals residing in a residential treatment facility for people with co-occurring disorders. Arrest data were obtained for 2 years following treatment intake. Regression analyses were employed to examine interactions between study variables. Results,One third of the sample was arrested during the 2-year follow-up period, principally for drug offences. People referred to treatment directly from the criminal justice system were four times more likely to re-offend than those referred from other sources. Participants' perceived need for mental-health services reduced risk of arrest while their perception of medical needs increased this risk. Conclusions,The relationship between referral from a criminal justice source and re-arrest after admission to the treatment facility is unsurprising, and consistent with previous literature, but the suggestion of an independently increased risk in the presence of perceived physical health-care needs is worthy of further study. The lower risk of arrest for people who perceive that they have psychological needs is encouraging. Copyright © 2009 John Wiley & Sons, Ltd. [source] QTc-interval abnormalities in a forensic populationCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 2 2007Sobhi Girgis Background,Antipsychotic drugs have been linked to sudden death among psychiatric patients, with a suggestion that prolongation of the QT-interval detectable on a standard electrocardiogram may be linked to fatal cardiac arrhythmias in these circumstances. Patients in secure forensic psychiatric facilities may be particularly likely to be on high-dose antipsychotic medication, and yet, as far as the authors are aware, no study of QT-intervals among such patients has been reported. Aim,To investigate the prevalence of QT-interval abnormalities and associated known risk factors for fatal cardiac arrhythmias in a sample of forensic patients. Method,Participants had a 12-lead electrocardiogram taken at 50 mm/s. Information was collected on their age, gender, psychiatric diagnosis, history of cardiovascular, liver and kidney diseases, and smoking, on all medications and on history of seclusion over the previous 12 months. Analysis was carried out using binary logistic regression. Results,Lower rates of QT-interval abnormalities than might be expected for this population were found. It was also found that a high dose of antipsychotics was associated with QTc prolongation (Adjusted OR = 9.5, 95% CI 2.6,34.2), a result consistent with previous literature. Conclusion,Forensic patients need not be at increased risk of QTc abnormality provided risk factors are properly managed. A high dose of antipsychotic medication increases the risk of QTc prolongation. Copyright © 2007 John Wiley & Sons, Ltd. [source] Name change among offender patients: an English high security hospital sampleCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 4 2002Birgit Völlm Clinical Research Fellow Background There is scant literature on change of name among psychiatric patients but a more substantial amount on the use of aliases among offenders. No one to our knowledge has explored name changes among offender patients. Aim This study was undertaken to establish the prevalence of name change among high security hospital patients and to compare those who changed name with those who did not. Hypothesis It was hypothesized that name change would be associated with male gender, repeated offending and a diagnosis of personality disorder. Method The clinical records of all patients resident in one high security hospital on 31 January 2000 were searched. As all such patients are compulsorily detained, all name changes must be recorded. Any change prior to that date was also noted, together with basic demographic and diagnostic information; supplementary data were obtained from the special hospitals' case register. Results Seventy-one patients (17%) of the resident population changed names (exclusive of a woman changing her surname on marriage). Name changing was associated with disrupted upbringing. Patients with personality disorder were more likely to change names than those with psychosis, regardless of sex, age or ethnic group. Those with psychosis were more likely to select unusual or symbolic names. Conclusions On the evidence of previous literature, people from this serious offender patient population were more likely to change names than other psychiatric patients but less likely than non-mentally-disordered offenders. Changes by people with psychosis seemed related to their illness, whereas changes by those with personality disorder might reflect childhood disruptions in rearing patterns. Copyright © 2002 Whurr Publishers Ltd. [source] Changes in hip spasticity and strength following selective dorsal rhizotomy and physical therapy for spastic cerebral palsyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 4 2002Jack R Engsberg PhD Hip adductor spasticity and strength in participants with cerebral palsy (CP) were quantified before and after selective dorsal rhizotomy (SDR) and intensive physical therapy. Twenty-four participants with cerebral palsy (CP group) and 35 non-disabled participants (ND controls) were tested with a dynamometer (CP group: mean age 8 years 5 months, 13 males, 11 females; ND group: mean age 8 years 6 months, 19 males, 16 females). According to the Gross Motor Function Classification System (GMFCS), of the 24 participants with CP, eight were at level I, six were at level II, and 10 participants were at level III. For the spasticity measure, the dynamometer quantified the resistive torque of the hip adductors during passive abduction at 4 speeds. The adductor strength test recorded a maximum concentric contraction. CP group spasticity was significantly reduced following SDR and adductor strength was significantly increased after surgery. Both pre- and postoperative values remained significantly less than the ND controls. Spasticity results agreed with previous studies indicating a reduction. Strength results conflicted with previous literature subjectively reporting a decrease following SDR. However, results agreed with previous objective investigations examining knee and ankle strength, suggesting strength did not decrease following SDR. [source] Deletion of 8p: a report of a child with normal intelligenceDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 12 2001Linda Gilmore PhD The case is presented of a female infant with a distal deletion of 8p (8p23.1,pter) whose development was monitored over a 5-year period from 12 months of age. Although previous literature has suggested that 8p deletion is associated with mild to moderate intellectual disability, the child reported here has normal intelligence. Despite initial delays in gross motor and language skills, cognitive development (assessed with the Bayley Scales of Infant Development) and intellectual ability (measured on the Stanford-Binet Intelligence Scale) were within average range. It is argued that the small number of previous case reports may have created a misleading impression of intellectual development in individuals with distal deletions of 8p. [source] Understanding the temporal dynamics of the wandering Renous River, New Brunswick, CanadaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2005Leif M. Burge Abstract Wandering rivers are composed of individual anabranches surrounding semi-permanent islands, linked by single channel reaches. Wandering rivers are important because they provide habitat complexity for aquatic organisms, including salmonids. An anabranch cycle model was developed from previous literature and field observations to illustrate how anabranches within the wandering pattern change from single to multiple channels and vice versa over a number of decades. The model was used to investigate the temporal dynamics of a wandering river through historical case studies and channel characteristics from field data. The wandering Renous River, New Brunswick, was mapped from aerial photographs (1945, 1965, 1983 and 1999) to determine river pattern statistics and for historical analysis of case studies. Five case studies consisting of a stable single channel, newly formed anabranches, anabranches gaining stability following creation, stable anabranches, and an abandoning anabranch were investigated in detail. Long profiles, hydraulic geometry, channel energy, grain size and sediment mobility variables were calculated for each channel. Within the Renous study area, the frequency of channel formation and abandonment were similar over the 54 years of analysis, indicating that the wandering pattern is being maintained. Eight anabranches were formed through avulsions, five were formed through the emergence of islands from channel bars and 11 anabranches were abandoned. The stable anabranch pair displayed similar hydraulic geometry and channel energy characteristics, while unstable anabranch pairs did not. The anabranch pair that gained stability displayed more similar channel energy characteristics than the anabranch pair that was losing stability (abandoning). It appears that anabranch pairs with similar energy characteristics are more stable than anabranches where these characteristics are out of balance. This is consistent with the hypothesis that anabranch pairs of similar length will be more stable than those with dissimilar lengths. Copyright © 2005 John Wiley & Sons, Ltd. [source] Migration within England and Wales and the Housing MarketECONOMIC OUTLOOK, Issue 3 2005Article first published online: 27 JUL 200 Economic conditions exert a strong influence on regional migration. On the one hand, strong labour market conditions, as exemplified by low unemployment rates and high earnings, draw migrants into regions. On the other hand, strong housing market conditions can prevent movement since commuting may often be an alternative to migration. This can be thought of as giving rise to a migration equilibrium where high house prices choke off migration caused by strong labour market conditions. Expected capital gains in housing, however, can offset high levels of house prices, an effect ignored in previous literature. Migration can also be influenced more directly by the availability of housing relative to population without this being mediated through prices. This paper, by Gavin Cameron, John Muellbauer and Anthony Murphy, presents evidence on inter-regional net and gross migration between the regions of England and Wales that is broadly in accord with these expectations. [source] Welfare Comparisons: Sequential Procedures for Heterogeneous PopulationsECONOMICA, Issue 276 2002Peter J. Lambert Some analysts use sequential dominance criteria, and others use equivalence scales in combination with non-sequential dominance tests, to make welfare comparisons of joint distributions of income and needs. In this paper we present a new sequential procedure which copes with situations in which sequential dominance fails. We also demonstrate that the recommendations deriving from the sequential approach are valid for distributions of equivalent income whatever equivalence scale the analyst might adopt. Thus, the paper marries together the sequential and equivalizing approaches, seen as alternatives in much previous literature. All results are specified in forms that allow for demographic differences in the populations being compared. [source] The relationship between baseline value and its change: problems in categorization and the proposal of a new methodEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2005Yu-Kang Tu Oral health researchers have shown great interest in the relationship between the initial status of diseases and subsequent changes following treatment. Two main approaches have been adopted to provide evidence of a positive association between baseline values and their changes following treatment. One approach is to use correlation or regression to test the relationship between baseline measurements and subsequent change (correlation/regression approach). The second approach is to categorize the lesions into subgroups, according to threshold values, and subsequently compare the treatment effects across the two (or more) subgroups (categorization approach). However, the correlation/regression approach suffers a methodological weakness known as mathematical coupling. Consequently, the statistical procedure of testing the null hypothesis becomes inappropriate. Categorization seems to avoid the problem of mathematical coupling, although it still suffers regression to the mean. We show, first, how the appropriate null hypothesis may be established to analyze the relationship between baseline values and change in the correlation approach and, second, we use computer simulations to investigate the impact of regression to the mean on the significance testing of the differences in the average treatment effects (or average baseline values) in the categorization approach. Data available from previous literature are reanalyzed by testing the appropriate null hypotheses and the results are compared to those from testing the usual (incorrect) null hypothesis. The results indicate that both the correlation and categorization approaches can give rise to misleading conclusions and that more appropriate methods, such as Oldham's method and our new approach of deriving the correct null hypothesis, should be adopted. [source] Divalent Samarium Triflate Mediated Stereoselective Pinacol Coupling of Planar Chiral Phosphanyl and Phosphoryl FerrocenecarbaldehydeEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2009Shin-ichi Fukuzawa Abstract The pinacol coupling reaction of (Rp)-2-diphenylphosphanyl ferrocenecarbaldehyde (1) was smoothly mediated by divalent samarium triflate to give (R,R)-diol 2a predominantly, whereas the use of samarium(II) iodide resulted in low selectivity as described in the previous literature. In contrast, the coupling reaction of (Rp)-2-diphenylphosphoryl ferrocenecarbaldehyde (3) with Sm(OTf)2 gave the (S,S)-diol as the major isomer, which was the opposite stereochemistry of that obtained in the reaction with 1. The rhodium complexes of diphosphanes 2a were good catalysts for the asymmetric hydrogenation of ,-acetamidocinnamic acid, and the product was obtained quantitatively with up to 92,%,ee. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Sex differences in the estimated intelligence of school childrenEUROPEAN JOURNAL OF PERSONALITY, Issue 3 2002Adrian Furnham This study investigated sex differences in estimated general and multiple intelligence in school children, their parents, and their teachers. There were three groups of participants: 285 (149 female, 136 male) pupils of a mixed government-run comprehensive school, between the ages of 13 and 16 years; 93 mothers and 58 fathers of the pupils; and five female and eight male teachers. Children estimated their own and their parents' IQ, whilst the parents estimated their own and their children's IQ; the teachers estimated only the children's intelligence. The aims of this study were firstly to assess whether perceptions of male intellectual superiority were observable in school age children and school teachers, and to make direct comparisons between the children's self-estimations and those of the parents and the teachers. Secondly, this study aimed to replicate previous literature on adult self-estimations of overall and multiple intelligences, and to compare these to estimations by children of these adults (their parents). Fewer sex differences were observed than expected. Teachers' estimations did not follow conceptions of male superiority. The patterns of sex differences in mother and teacher estimations of children were similar to each other, as were those of fathers and children. Verbal and numerical abilities were found to be most closely related to estimations of overall IQ in all three groups. Most striking was the lack of correlation between father and daughter estimations of each other. Reasons why this study failed to replicate findings on adult samples are discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] S,N curve characteristics and subsurface crack initiation behaviour in ultra-long life fatigue of a high carbon-chromium bearing steelFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 12 2001K. Shiozawa The S,N curve obtained from cantilever-type rotary bending fatigue tests using hour-glass-shaped specimens of high carbon-chromium bearing steel clearly distinguished the fracture modes into two groups each having a different crack origin. One was governed by crystal slip on the specimen surface, which occurred in the region of short fatigue life and a high stress amplitude level. The other was governed by a non-metallic inclusion at a subsurface level which occurred in the region of long fatigue life and low stress amplitude. The inclusion developed a fish-eye fracture mode that was distributed over a wide range of stress amplitude not only below the fatigue limit defined as the threshold for fracture due to the surface slip mode but also above the fatigue limit. This remarkable shape of the S,N curve was different from the step-wise one reported in previous literature and is characterized as a duplex S,N curve composed of two different S,N curves corresponding to the respective fracture modes. From detailed observations of the fracture surface and the fatigue crack origin, the mechanisms for the internal fracture mode and the characteristics of the S,N curve are discussed. [source] Helicobacter pylori and Hepatitis a Virus Infection in School-Aged Children on Two Isolated Neighborhood Islands in TaiwanHELICOBACTER, Issue 3 2003Liang-Kung Chen ABSTRACT Background. The transmission routes of Helicobacter pylori and hepatitis A virus (HAV) infections have been extensively discussed in previous literature. However, whether H. pylori and HAV shared the same transmission pattern or not remains unclear. Lower socioeconomic status was recognized as a consistent risk factor to both infections. However, whether fecal-oral transmission was a risk factor to both infections is still under debate. Materials and Methods. In 1996, we conducted a cross-sectional study to evaluate the seroprevalence of antibody to H. pylori and HAV among the randomly selected school-aged children (age between 13 and 15) on Green Island (n = 91) and Lanyu Island (n = 138) (two isolated neighborhood islands near Taiwan Main Island). Results. The seroprevalence of H. pylori and HAV on the Green Island were 82.4% and 5.5%, respectively. The seroprevalence of H. pylori and HAV on Lanyu Island were 71.0% and 90.6%, respectively. H. pylori seroprevalence of all children and the subgroup of 13-year-olds was significantly lower on Lanyu Island than Green Island. However, it was not significantly different in subgroups of 14- and 15-year-olds. HAV seroprevalence was significantly higher on Lanyu Island than Green Island among all children and in each age subgroup. The correlation of H. pylori infection and HAV infection did not demonstrate significant linear correlation on both islands. Conclusions. In conclusion, H. pylori and HAV infections in school-aged children of 13,15 years of age on Green Island and Lanyu Island did not demonstrate significant correlation. The results of this study imply that H. pylori and HAV may share different transmission routes of infection. [source] Perception of safe robot speed in virtual and real industrial environmentsHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 4 2006Vincent G. Duffy The purpose of this project was to study the influences of dynamic virtual objects in an Internet-based virtual industrial environment. The main objectives of this study were to investigate perception of safe robot speed and perception of acceptability. Virtual industrial environments were designed and developed to conduct the experiment. The hypotheses specifying the relationships between perceptions of the robot size, type, different robot starting speed conditions, and gender were tested through data collected from 32 participants. The results indicated that the perception of safe speed was significantly different depending on robot sizes and the initial robot speed conditions. This was consistent with results shown in previous literature for tests in a real industrial environment. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 369,383, 2006. [source] The Pearls and Perils of Identifying PotentialINDUSTRIAL AND ORGANIZATIONAL PSYCHOLOGY, Issue 4 2009ROB SILZER Organizations today are increasingly focused on talent as a strategic asset and a competitive advantage for achieving business success. As a result, most major organizations have recognized the need for and outlined a formal process to identify and assess high-potential talent. There is, however, little agreement within or between organizations on the definition and components of the concept of potential. The existing definitions and models of potential are often narrowly focused on only a few select factors and give little attention to the broad spectrum of potential talent in an organization. This article introduces a new integrated model of potential that incorporates previous literature and current assessment practice regarding high potentials, provides a coherent structure of potential, and is reflective of a variety of different talent pools. The model provides a useful method for answering the key question,Potential for what? Three key components of potential are described by the model: (a) foundational dimensions, (b) growth dimensions, and (c) career dimensions. Implications for assisting organizations in more effectively managing their high potential talent for strategic business objectives are discussed. [source] Lateral stress caused by horizontal and vertical surcharge strip loads on a cross-anisotropic backfillINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2005Cheng-Der Wang Abstract This study derives analytical solutions for estimating the lateral stress caused by horizontal and vertical surcharge strip loads resting on a cross-anisotropic backfill. The following loading types are employed in this work: point load, line load, uniform strip load, upward linear-varying strip load, upward nonlinear-varying strip load, downward linear-varying strip load and downward nonlinear-varying strip load. The cross-anisotropic planes are assumed to be parallel to the horizontal surface of the backfill. The solutions proposed herein have never been mentioned in previous literature, but can be derived by integrating the point load solution in a Cartesian co-ordinate system for a cross-anisotropic medium. The calculations by the presented solutions are quick and accurate since they are concise and systematized. Additionally, the proposed calculations demonstrate that the type and degree of material anisotropy and the horizontal/vertical loading types decisively influence the lateral stress. This investigation presents examples of the proposed horizontal and vertical strip loads acting on the surface of the isotropic and cross-anisotropic backfills to elucidate their effects on the stress. The analytical results reveal that the stress distributions accounting for soil anisotropy and loading types are quite different from those computed from the available isotropic solutions. Restated, the derived solutions, as well as realistically simulating the actual surcharge loading circumstances, provide a good reference for the design of retaining structures for the backfill materials are cross-anisotropic. Copyright © 2005 John Wiley & Sons, Ltd. [source] Adaptive tracking control for electrically-driven robots without overparametrizationINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2 2002Yeong-Chan Chang Abstract This paper addresses the motion tracking control of robot systems actuated by brushed direct current motors in the presence of parametric uncertainties and external disturbances. By using the integrator backstepping technique, two kinds of adaptive control schemes are developed: one requires the measurements of link position, link velocity and armature current for feedback and the other requires only the measurements of link position and armature current for feedback. The developed adaptive controllers guarantee that the resulting closed-loop system is locally stable, all the states and signals are bounded, and the tracking error can be made as small as possible. The attraction region can be not only arbitrarily preassigned but also explicitly constructed. The main novelty of the developed adaptive control laws is that the number of parameter estimates is exactly equal to the number of unknown parameters throughout the entire electromechanical system. Consequently, the phenomenon of overparametrization, a significant drawback of employing the integrator backstepping technique to treat the control of electrically driven robots in the previous literature, is eliminated in this study. Finally, simulation examples are given to illustrate the tracking performance of electrically driven robot manipulators with the developed adaptive control schemes. Copyright © 2002 John Wiley & Sons, Ltd. [source] |