Effect of Head Movement on Sound Localization in Real and Simulated Cochlear Implant Users

Cochlear implant (CI) users’ limited ability to use acoustical cues for sound localization causes left/right confusions and front/back reversals. Head movement is beneficial in reducing these errors in acoustically hearing listeners. This study investigated the effect of head movement on localization throughout 360o of azimuth for both real and simulated CI users. Listeners in a bilateral electro-acoustic (CI with ipsilateral hearing aid) simulation derived the greatest head movement benefit in reducing front/back reversals. Left/right confusions were reduced in simulations with matched bilateral stimulation. Sensitivity to both timing and level cues for sound localization was correlated with sound localization performance without head movement for simulated device users. Sensitivity to timing cues was correlated with sound localization performance with head movement cues for simulated device users. Simulations of bilateral CI and bimodal users (CI with contralateral hearing aid) listening predicted real users’ sound localization performance, binaural sensitivity and head movement patterns

Image analysis of dominant ovarian follicles and ovarian follicular development during continuous and conventional oral contraceptive dosing schemes

The objective of this research was to assess ultrasound image attributes of human dominant ovarian follicles in the final stages of development during natural and oral contraceptive (OC) cycles, as well as characterize ovarian follicular and endometrial development during and after continuous versus conventional dosing schemes. We utilized sophisticated computer algorithms to elucidate an association between image attributes and physiologic status of follicles in their final stage of development. We used transvaginal ultrasonography to quantify changes in the numbers and diameters of ovarian follicles and changes in endometrial thickness and pattern during and following discontinuation of two different regimens of OC. Developmental changes in ovarian follicles and corpora lutea were correlated with serum estradiol-17â and progesterone, respectively to provide a comprehensive approach to examining ovarian and uterine function. We reported for the first time that follicles which develop during natural and OC cycles have similar image attributes, which provides preliminary evidence that image attributes of human follicles are associated with physiologic status during the growth phase. Further research should be performed to elucidate the exact correlation between image attributes during all stages of follicular development throughout the menstrual cycle, prediction of dysfunctional follicular development (i.e., hemorrhagic anovulatory follicles) and the effects of different OC formulations on follicle development. Once the association between image attributes and various scenarios of follicular development are determined, a computer program could be developed to assess follicular health with a single ultrasound examination, obviating many ethical constraints that currently prevent large scale progress in ovarian follicular research. We further documented that continuous OC administration schemes provide greater follicular suppression than conventional dosing schemes. No dominant follicles developed during three consecutive 28 day cycles of continuous OC use, whereas eight dominant follicles developed during the same time period of conventional OC use. We interpreted these findings to mean that continuous OC dosing schemes provide a more effective contraceptive with a decreased risk of “escape” ovulation compared to conventional dosing schemes. Most follicles ovulated in the immediate cycle following discontinuation of OC. We suggest that the delay to fertility following cessation of OC is not due to anovulation but other yet, unknown, biological factors

Effects of formal mentoring support on newcomer-protégé affective organizational commitment:a self-concept-based perspective

The study proposes and tests a self-concept-based perspective for the effects of formal mentoring support on affective organizational commitment (AOC) via multiple mediators. Using time-lagged multi-source dyadic data (n = 203), we demonstrate that formal mentoring support significantly influences newcomer-proteges' AOC through an underlying self-evaluative mechanism indicated by organization-based self-esteem (OBSE), even in the presence of a well-established alternative mediator (perceived organizational support; POS). Moreover, we further demonstrate when or under what circumstances such effects might be attenuated or exaggerated by introducing a salient boundary condition to such a process (i.e., perceived mentor organizational prototypicality). As the findings reveal, by making newcomer-proteges feel good about themselves in the workplace (i.e., perceive self-value) formal mentoring support can also promote organizational commitment, effects that are likely to be amplified when the formal mentor is perceived to be prototypical of the organization. Thus, bridging the mentoring and socialization literatures, the inclusion of our proposed mediators and moderator and testing their relationships simultaneously not only provides a more nuanced view of the underlying mechanisms through which the effects of formal mentoring support are channeled to influence newcomer-proteges' work attitudes but it offers new theoretical elaboration and contextual understanding that we hope will prompt future research and be of benefit to human resource practitioners. Implications to theory, practice and future research directions are discussed

The influence of year, period, supersector, and business specific effects on the profitability of South African publicly listed companies

The determinants of profitability should be at the forefront of CEO’s, managers and business owners minds. Whether the business takes a stockholder or stakeholder approach profit maximisation is the source for the sustainability of a business. International research has been conducted since the 1970’s to establish the effects year, company and industry structure have on the profitability of companies. There is still no consensus as to which variables have the greatest effect on performance of firms. A quantitative research methodology was followed whereby all organisations listed on the Johannesburg Stock Exchange were categorised into their respective Supersectors for the period 1983 to 2008. The performance measures of return on assets, return on equity and return on capital employed were then calculated for all companies and analysed across year, period, company, interaction of company and year, interaction of company and period and finally against Supersector. Five of the six hypotheses in the Variance Component tests showed a variation and one did not. Of these, Supersector was seen as having no variance, and hence no impact on the profitability of firms. Year, period, company and the interactions of these showed significant variance in determining profitability. These results show that year, period (pre and post apartheid) and company do have an effect on the profitability of listed companies. This study allows for Corporate Strategists to focus their efforts on the areas that will have the greatest impact.Dissertation (MBA)--University of Pretoria, 2010.Gordon Institute of Business Science (GIBS)unrestricte

Ultrasound image attributes of human ovarian dominant follicles during natural and oral contraceptive cycles

BACKGROUND: Computer-assisted analyses were used to examine ultrasound image attributes of human dominant ovarian follicles that developed during natural and oral contraceptive (OC) cycles. We hypothesized that image attributes of natural cycle follicles would quantitatively differ from those in OC cycles and that OC cycle follicles would possess image attributes indicative of atresia. METHODS: Dominant ovarian follicles of 18 clinically normal women were compared using transvaginal ultrasonography for the 7 days before ovulation during a natural cycle (n = 9) or the 7 days before peak estradiol in women using OC (n = 11). Follicles were analyzed using region and line techniques designed to compare the image attributes numerical pixel value (NPV), pixel heterogeneity (PH) and area under the curve (AUC). RESULTS: NPV was higher in OC cycle follicles with region analysis and tended to be higher with line analysis (p = 0.005 and p = 0.06, respectively). No differences were observed in two other image attributes (AUC and PH), measured with either technique, between natural and OC cycle follicles. CONCLUSION: The increased NPV value of OC cycle follicles and lack of differences in PH and AUC values between natural cycle and OC cycle follicles did not support the hypothesis that OC cycle follicles would show ultrasonographically detectable signs of atresia. Image attributes observed in OC cycle follicles were not clearly indicative of atresia nor were they large enough to preclude preovulatory physiologic status in OC cycle follicles

Perceptions of negative workplace gossip:a self-consistency theory framework

We present and test a self-consistency theory framework for gossip: that perceived negative workplace gossip influences our self-perceptions and, in turn, this influences our behaviors. Using supervisor-subordinate dyadic time-lagged data (n = 403), we demonstrated that perceived negative workplace gossip adversely influenced target employees’ organization-based self-esteem, which, in turn, influenced their citizenship behavior directed at the organization and at its members. Moreover, by integrating victimization theory into our framework, we further demonstrated that negative affectivity, an individual’s dispositional tendency, not only moderated the self-consistency process but also predicted perceived negative workplace gossip. Our study therefore shifts attention to the target of negative workplace gossip and in doing so offers a promising new direction for future research. Implications to theory and practice are discussed

Fifteen years of clinical liver transplantation

Liver transplantation in humans was first attempted more than 15 yr ago. The 1-yr survival has slowly improved until it has now reached about 50%. In our experience, 46 patients have lived for at least 1 yr, with the longest survival being 9 yr. The high acute mortality in early trials was due in many cases to technical and management errors and to the use of damaged organs. With elimination of such factors, survival increased. Further improvements will depend upon better immunosuppression. Orthotopic liver transplantation (liver replacement) is the preferred operation in most cases, but placement of an extra liver (auxiliary transplantation) may have a role under special circumstances. © 1979

Analysis of the Pantoea ananatis pan-genome reveals factors underlying its ability to colonize and interact with plant, insect and vertebrate hosts

BACKGROUND: Pantoea ananatis is found in a wide range of natural environments, including water, soil, as part of the epi- and endophytic flora of various plant hosts, and in the insect gut. Some strains have proven effective as biological control agents and plant-growth promoters, while other strains have been implicated in diseases of a broad range of plant hosts and humans. By analysing the pan-genome of eight sequenced P. ananatis strains isolated from different sources we identified factors potentially underlying its ability to colonize and interact with hosts in both the plant and animal Kingdoms. RESULTS: The pan-genome of the eight compared P. ananatis strains consisted of a core genome comprised of 3,876 protein coding sequences (CDSs) and a sizeable accessory genome consisting of 1,690 CDSs. We estimate that ~106 unique CDSs would be added to the pan-genome with each additional P. ananatis genome sequenced in the future. The accessory fraction is derived mainly from integrated prophages and codes mostly for proteins of unknown function. Comparison of the translated CDSs on the P. ananatis pan-genome with the proteins encoded on all sequenced bacterial genomes currently available revealed that P. ananatis carries a number of CDSs with orthologs restricted to bacteria associated with distinct hosts, namely plant-, animal- and insect-associated bacteria. These CDSs encode proteins with putative roles in transport and metabolism of carbohydrate and amino acid substrates, adherence to host tissues, protection against plant and animal defense mechanisms and the biosynthesis of potential pathogenicity determinants including insecticidal peptides, phytotoxins and type VI secretion system effectors. CONCLUSIONS: P. ananatis has an ‘open’ pan-genome typical of bacterial species that colonize several different environments. The pan-genome incorporates a large number of genes encoding proteins that may enable P. ananatis to colonize, persist in and potentially cause disease symptoms in a wide range of plant and animal hosts.This study was partially supported by the University of Pretoria Postdoctoral Fellowship Program, National Research Foundation (NRF), the Tree Protection Co-operative Programme (TPCP), the NRF/Dept. of Science and Technology Centre of Excellence in Tree Health Biotechnology (CTHB), and the THRIP support program of the Department of Trade and Industry, South Africa. IKT and PRJB were supported by a grant from the Scottish Government’s Rural and Environmental Science and Analytical Services (RESAS) division.http://www.biomedcentral.com/1471-2164/15/404am201

Hospitality workers’ COVID-19 risk perception and depression: A contingent model based on transactional theory of stress model

The hospitality industry worldwide is suffering under the COVID-19 pandemic. Drawing on the transactional theory of stress and coping, this study aims to investigate when hospitality workers’ COVID-19 risk perception affects their likelihood of having depressive symptoms. Using data from 211 hospitality workers in 76 hotels in Peru, we examined the effects of perceived COVID-19 risk on the likelihood of experiencing depressive symptoms. We posited that this relationship is moderated by the workers’ environment at work (job satisfaction) and at home (the number of children). The results indicate that job satisfaction weakens the link between hospitality workers’ COVID-19 risk perception and their likelihood of depressive symptoms while the number of children exacerbates this link. We discuss the implications of our findings for research on COVID-19 risk perception and offer practical implications for hospitality workers under COVID-19 crisis