Predicting counterproductive work behavior with narrow personality traits : a nuanced examination using quantile regression

Abstract: Conditional means models such as linear regression is a conventional method that researchers regularly employ to examine relationships between personality traits and counterproductive work behavior. However, this method has several shortcomings limiting its utility. Quantile regression analysis better accounts for many of these limitations. This study investigates narrow personality traits as predictors of counterproductive workplace behavior using quantile methods with 952 working adults. Results show that quantile regression analysis provides a more nuanced representation of the relationship that personality traits have with counterproductive workplace behavior. We demonstrate that the conditional mean (i.e., regression coefficient) observed with standard ordinary least squares regression overestimates regression parameters at low levels of counterproductive work behavior, and underestimates it at high levels. The findings from this study suggest that reliance on conditional means models for the prediction of CWB may have resulted in an incomplete understanding and under appreciation of personality’s actual value for the prediction of workplace deviance

Magnetoplasmon excitations in an array of periodically modulated quantum wires

Motivated by the recent experiment of Hochgraefe et al., we have investigated the magnetoplasmon excitations in a periodic array of quantum wires with a periodic modulation along the wire direction. The equilibrium and dynamic properties of the system are treated self-consistently within the Thomas-Fermi-Dirac-von Weizsaecker approximation. A calculation of the dynamical response of the system to a far-infrared radiation field reveals a resonant anticrossing between the Kohn mode and a finite-wavevector longitudinal excitation which is induced by the density modulation along the wires. Our theoretical calculations are found to be in excellent agreement with experiment.Comment: 9 pages, 8 figure

Exact results for a charged, harmonically trapped quantum gas at arbitrary temperature and magnetic field strength

An analytical expression for the first-order density matrix of a charged, two-dimensional, harmonically confined quantum gas, in the presence of a constant magnetic field is derived. In contrast to previous results available in the literature, our expressions are exact for any temperature and magnetic field strength. We also present a novel factorization of the Bloch density matrix in the form of a simple product with a clean separation of the zero-field and field-dependent parts. This factorization provides an alternative way of analytically investigating the effects of the magnetic field on the system, and also permits the extension of our analysis to other dimensions, and/or anisotropic confinement.Comment: To appear in Phys. Rev.

Fifty years of thoracic surgical research in South Africa

Aim. To investigate the scope and trends in clinical research inSouth African thoracic surgery between 1955 and 2006 and tomeasure its impact on clinical practice.Method. A systematic review of all SA thoracic surgicalpublications was performed.Results. There were 252 general thoracic publications and amarked decrease in publications was noted after the peakperiod of productivity of the 1980s. There was a shift towardthe private sector as an origin of articles and toward a local,non-indexed journal. Inflammatory lung disease was themost frequent topic of publication. Case series and casereports were the most frequent type of article.Conclusion. The vulnerability of a small specialty in adeveloping country is illustrated by the clear trends thatemerged. The study provides important indicators for futureresearch, highlights the need for a national database of clinicalexperience, and emphasises the importance of rekindlinginterest and a culture of research in thoracic surgery

Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements

© 2016 The Author(s). Published by Copernicus Publications on behalf of the European Geosciences Union. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence ( https://creativecommons.org/licenses/by/3.0/ ), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type is available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol properties, i.e. effective radius and single scattering albedo were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the lidar ratio at 532 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr; 41 ± 13 sr; 0.9 ± 0.4 % and 2.3 ± 0.5, respectively for urban / industrial aerosols, while these values were 92 ± 10 sr; 75 ± 14; 3.2 ± 1.3 % and 1.7 ± 0.3 respectively for biomass burning aerosols layers. Biomass burning particles are larger and slightly less absorbing compared to urban / industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03 μm, 0.17 ± 0.04 μm and 0.13 ± 0.03 μm for urban/industrial, biomass burning, and mixed aerosols, respectively, while the single scattering albedo at 532 nm were 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532 nm), respectively for these three types of aerosols. Our results were within the same range of previously reported values.Peer reviewedFinal Published versio

Theoretical Modeling of the Thermal State of Accreting White Dwarfs Undergoing Classical Novae

White dwarfs experience a thermal renaissance when they receive mass from a stellar companion in a binary. For accretion rates < 10^-8 Msun/yr, the freshly accumulated hydrogen/helium envelope ignites in a thermally unstable manner that results in a classical novae (CN) outburst and ejection of material. We have undertaken a theoretical study of the impact of the accumulating envelope on the thermal state of the underlying white dwarf (WD). This has allowed us to find the equilibrium WD core temperatures (T_c), the classical nova ignition masses (M_ign) and the thermal luminosities for WDs accreting at rates of 10^-11 - 10^-8 Msun/yr. These accretion rates are most appropriate to WDs in cataclysmic variables (CVs) of P_orb <~ 7 hr, many of which accrete sporadically as dwarf novae. We have included ^3He in the accreted material at levels appropriate for CVs and find that it significantly modifies the CN ignition mass. We compare our results with several others from the CN literature and find that the inclusion of ^3He leads to lower M_ign for >~ 10^-10 Msun/yr, and that for below this the particular author's assumption concerning T_c, which we calculate consistently, is a determining factor. Initial comparisons of our CN ignition masses with measured ejected masses find reasonable agreement and point to ejection of material comparable to that accreted.Comment: 14 pages, 11 figures; uses emulateapj; accepted by the Astrophysical Journal; revised for clarity, added short discussion of diffusio

Late-night simulation: Opinions of fourth- and fifth-year medical students at the University of the Free State, Bloemfontein, South Africa

Background. Sleep deprivation is a problem for medical students and practitioners due to long and late working hours, which may result in a decline in their performance in practising medicine. Objectives. To investigate whether educational practices require altering with regard to the time at which simulation classes are presented, or identify any other possible suggestions for improving the preparation of students for shift work in their profession as medical doctors as a potential solution to reduce sleep-deprivation-related adverse outcomes. Methods. In this quantitative cross-sectional study, an anonymous questionnaire was distributed to 111 fourth-year and 141 fifth-year medical students at the Faculty of Health Sciences, University of the Free State (UFS), Bloemfontein, South Africa, during the second half of 2018. The researchers interpreted the responses and the Department of Biostatistics, UFS, analysed the data. Results. The majority of the fourth-year (88.6%) and fifth-year (90.4%) student groups responded that late-night simulation classes between 01h00 and 04h00 would not be beneficial to their preparation for shift work. The motivation for negative responses was that it might worsen sleep deprivation due to time constraints in an already demanding course. The fourth-year (61.4%) and fifth-year (80.5%) student groups did not regard simulation as realistic and felt that late-night simulation training sessions would not prepare them better for future shift work. However, both groups believed ‘practice makes perfect’ and, as such, their confidence with procedures would improve as they practise more during simulation. Conclusion. The majority of students were negative towards the idea of late-night simulation classes, because of the effect it would have on their already full programme. Students are familiar with the effects of sleep deprivation and felt that late-night simulation classes would add pressure to their busy lives and worsen their sleep deprivation. Further investigation and practical testing would be required to conclude the impact of late-night simulation classes in preparation for shift work of medical doctors and the resultant effect on clinical performance

Ekonomie 2B

Exam paper for second semester: Ekonomie 2

Help-seeking by substance dependants presenting to healthcare professionals in the Free State Province

Introduction. Current data regarding treatment needs in South Africa for substance dependence are based on admissions to specialised treatment centres. The data therefore do not include patients presenting to independent healthcare workers and state hospitals. Aim. The aim of this study was to investigate help-seeking behaviour for substance dependence disorders from the perspective of healthcare professionals at various levels of the referral chain in Free State Province. Design. A descriptive study was performed. Setting. Treatment environments in Free State Province accessible to substance-dependent persons. Participants. General practitioners, private psychiatrists, prescribing healthcare professionals at state hospitals and treatment centres, and non-prescribing therapists responsible for management of substance-dependent persons. Measurements. A questionnaire was used to determine the level of help-seeking experienced by the participants regarding various classes of psycho-active substances. Findings. The presentation of alcohol, cannabis, opioid, benzodiazepine, ecstasy, cocaine and inhalant dependency at general practitioners, private psychiatrists, treatment centres and non-prescribing therapists was compared. Different patterns of help-seeking for substance dependence from the various professional groups were detected. Regarding alcohol dependence, 40.3% of private general medical practitioners reported being confronted with alcohol dependence at least once per month, compared with 100% of treatment centre representatives and private psychiatrists, 70.6% of state hospitals and 53.8% of non-prescribers. State hospitals reported the highest frequency for contact with cases of cannabis dependence, compared with the other professional groups, while psychiatrists reported the highest contact with cases involving benzodiazepine, cocaine and ecstasy. Therapists reported a higher level of contact with inhalant dependence, while this group virtually never presented at general practitioners and private psychiatrists. Conclusion. Help-seeking data can be used in conjunction with other data, such as treatment demand data, to inform and adapt policies and practice. Variations in the manifestation of help-seeking behaviour at various groups may be important pointers to conditions that influence help-seeking, and therefore should be investigated further