Acoustic oscillations of rapidly rotating polytropic stars. II. Effects of the Coriolis and centrifugal accelerations

Context: With the launch of space missions devoted to asteroseismology (like COROT), the scientific community will soon have accurate measurements of pulsation frequencies in many rapidly rotating stars. Aims: The present work focuses on the effects of rotation on pulsations of rapidly rotating stars when both the Coriolis and centrifugal accelerations require a non-perturbative treatment. Method: We develop a 2-dimensional spectral numerical approach which allows us to compute acoustic modes in centrifugally distorted polytropes including the full influence of the Coriolis force. This method is validated through comparisons with previous studies, and the results are shown to be highly accurate. Results: In the frequency range considered and with COROT's accuracy, we establish a domain of validity for perturbative methods, thus showing the need for complete calculations beyond v.sin i = 50 km/s for a R = 2.3 R_\odot, M = 1.9 M_\odot polytropic star. Furthermore, it is shown that the main differences between complete and perturbative calculations come essentially from the centrifugal distortion.Comment: published in A&A, corrected minor mistakes and updated some reference

Personal leadership as an antecedent of servant leadership

Abstract: Organisational failures and leadership challenges in South African banks have attracted a growing interest in the value of Personal Leadership behaviours. Although this concept was commonly established to focus on employees regulating their own behaviours, as yet, relatively has not been extended to organisational leaders leading themselves. It is therefore a relatively new and seldom empirically studied concept in the South African context. Most of the leadership interventions are externally oriented instead of being introspective strategies embedded in the principles of personal regulation. The purpose of this study was to explore Personal Leadership as an antecedent of Servant Leadership among bank managers in South Africa. Personal Leadership and its associated dimensions (Personal Goal Setting, Personal Rehaviour Regulation, Personal Dialogue, Personal Motivation, Personal Cueing, and Focusing on Intrinsic Rewards) were used as independent variables while Servant Leadership and its associated dimensions (Altruistic Calling, Emotional Healing, Wisdom, Persuasive Mapping and Organisational Stewardship) were used as dependent variables in this study. A quantitative research method approach was used to test the underlying theoretical constructs. Primary data was collected via a selfadministered questionnaire. A convenience sampling approach was followed. A sample size of N=230 bank managers located in the the Gauteng and Limpopo provinces of South Africa were sought and obtained. To measure Personal Leadership, a 35-item five-point rating scale questionnaire adopted from Houghton and Neck (2002) was used. To measure Servant Leadership, a 23-item five-point rating scale questionnaire adopted from Barbuto and Wheeler (2006) was used. ..M.Phil. (Personal and Professional Leadership

The relationship between conscientiousness, extraversion and leadership effectiveness among local government managers in Bisho and East London

This study investigated the relationship between conscientiousness, extraversion, and leadership effectiveness among the local government managers in Bisho and East London. Conscientiousness and extraversion were used as independent variables in the study while leadership effectiveness was used as the dependent variable. The data was collected from a sample of 222 local government managers using a self-designed biographical and occupational questionnaire. To measure conscientiousness and extraversion, a 24-item 5-point rating scale adopted from Finchan & Rhodes (2005) was used. To measure leadership effectiveness, a 6-item 5-point derailment rating scale adopted from Lombardo & McCauley (1994) was used. Data analysis was done using various statistical techniques, including t-tests, Pearson Product Moment Correlation Technique and Multiple Regression Analysis. The results indicated that both conscientiousness and extraversion are strongly associated with leadership effectiveness. Conscientiousness was also strongly associated with the individual components of leadership effectiveness, interpersonal relationships; molding a staff; making strategic transitions; follow-through and ability to work independently. Extraversion was also strongly associated with the individual components of leadership effectiveness, molding a staff; making strategic transitions; strategic similarities with management; follow-through and ability to work independently. Although conscientiousness and extraversion combined were found to have an additive effect on leadership effectiveness, conscientiousness accounts for a higher proportion of variance in leadership effectiveness than extraversion. Finally, the results also indicated that age was strongly associated with leadership effectiveness. The study therefore recommends that organisations should use conscientiousness and extraversion when selecting individuals for leadership positions

Inert Drying System for Copper Paste Application in PV

AbstractIn this study we show that the electrical characteristics of low temperature polymer pastes are improved by carrying out the curing process in an inert nitrogen atmosphere. In order to reduce the solar cell production costs, numerous scientific works are devoted to the question, whether the commonly used silver paste can be replaced by a copper based paste. However, a major problem with the latter is, that copper tends to oxidate during the thermal treatment. Hence, this work focuses on the development of an inert inline drying system to avoid the oxidation of copper based polymer pastes. For reference, silver based polymer pastes are investigated simultaneously. Therefore the influence of different nitrogen curing atmospheres on the electrical resistance and the weight loss of the pastes is evaluated. The electrical resistance of both silver and copper based pastes is improved by reducing the residual oxygen concentration. To investigate the reason for this, the samples are analyzed by micrographics. Furthermore it is shown, that the weight loss of the pastes shows no dependence on the curing atmosphere

Surgical Versus Nonsurgical Management of Humeral Shaft Fractures:a systematic review and meta-analysis of randomised trials

Introduction: The aim was to compare operative and non-operative management for adults with humeral shaft fractures, in terms of patient-reported upper limb function, health-related quality of life (HRQoL), radiographic outcomes and complications.Methods: MEDLINE, Embase, CINAHL (Cumulative Index to Nursing and Allied Health Literature), PubMed, CENTRAL (Cochrane Central Register of Controlled Trials), ClinicalTrials.gov, ISRCTN (International Clinical Trials Registry) and OpenGrey (Repository for Grey Literature in Europe) were searched in September 2021. All published prospective randomised trials comparing operative and non-operative management of humeral shaft fractures in adults were included. Of 715 studies identified, five were included in the systematic review and four in the meta-analysis. Data were extracted by two independent reviewers according to the PRISMA statement. Methodological quality was assessed using the revised Cochrane risk-of-bias tool for randomised trials. Pooled data were analysed using a random-effects model.Results: The meta-analysis comprised 292 patients (mean age 41yrs [18-83], 67% male). Surgery was associated with superior DASH and Constant-Murley scores at six months (mean DASH difference 7.6, p=0.01; mean Constant-Murley difference 8.0, p=0.003) but there was no difference at one year (DASH, p=0.30; Constant-Murley, p=0.33). No differences in HRQoL or pain scores were found. Surgery was associated with a lower risk of nonunion (0.7% versus 15.7%; odds ratio [OR] 0.13, p=0.004). The number-needed-to-treat (NNT) with surgery to avoid one nonunion was 7. Surgery was associated with a higher risk of transient radial nerve palsy (17.4% versus 0.7%; OR 8.23, p=0.01) but not infection (OR 3.57, p=0.13). Surgery was also associated with a lower risk of re-intervention (1.4% versus 19.3%; OR 0.14, p=0.04).Conclusions: Surgery may confer an early functional advantage to adults with humeral shaft fractures, but this is not sustained beyond six months. The lower risk of nonunion should be balanced against the higher risk of transient radial nerve palsy.<br/

Accretion and Structure of Radiating Disks

We studied a steadily accreting, geometrically thick disk model that selfconsistently takes into account selfgravitation of the polytropic gas, its interaction with the radiation and the mass accretion rate. The accreting mass is injected inward in the vicinity of the central $z=0$ plane, where also radiation is assumed to be created. The rest of the disk remains approximately stationary. Only conservation laws are employed and the gas-radiation interaction in the bulk of the disk is described in the thin-gas approximation. We demonstrate that this scheme is numerically viable and yields a structure of the bulk that is influenced by the radiation and (indirectly) by the prescribed mass accretion rate. The obtained disk configurations are typical for environments in Active Galactic Nuclei (AGN), with the central mass of the order of 10^7 M_{\astrosun} to 10^8 M_{\astrosun}, quasi-Keplerian rotation curves, disk masses ranging from about 10^6 M_{\astrosun} to 10^7 M_{\astrosun}, and the luminosity ranging from 10^6 L_{\astrosun} to 10^9 L_{\astrosun}. These luminosities are much lower than the corresponding Eddington limit.Comment: Changes according to the version accepted by Astronomy & Astrophysic