Lobe interactions within the thallus margin and the maintenance of symmetry in the lichen Parmelia conspersa (Ehrh. ex Ach.)Ach.

This study determined whether the radial growth of lobes of the foliose lichen Parmelia conspersa (Ehrh. ex Ach.)Ach. was influenced by the radial growth and morphology of their closest neighbours and whether such interactions influence thallus symmetry. The radial growth and morphology of a sample of adjacent lobes from six thalli was measured. Positive correlations were observed between radial growth and lobe width in three thalli and with the degree of bifurcation of the lobe in two thalli. Negative correlations between the radial growth of adjacent lobes were observed in four thalli suggesting that faster growing lobes may inhibit the growth of their neighbours.Lobes glued next to individual lobes had no signifiacnt effect on the radial growth of wide or narrow lobes. Lobes glued 1-2 mm in front of their neighbours exhibited an intital phase of increased radial growth and then a phase of slower growth. Radial growth decreased when the lobes were glued 2 mm behind their neighbours and these lobes were essentially eliminated by the growth of the adjacent lobes. The data suggest that lobe interactions may incresae lobe growth variation within a thallus. However, the decrease in radial growth of lobes which protrude from the margin and the elimination of slower growing lobes may help to maintain thallus symmetry.

Lobe growth variation and the maintenance of symmetry in foliose lichen thalli

The aim of this study was to determine how thallus symmetry could be maintained in foliose lichens when variation in the growth of individual lobes may be high. Hence, the radial growth of a sample of lobes was studied monthly, over 22 months, in 7 thalli of Parmelia conspersa (Ehrh. Ex Ach.) Ach. And 5 thalli of P. glabratula ssp fuliginosa (fr. ex Duby) Laund. The degree of variation in the total radial growth of different lobes within a thallus over 22 months varied between thalli. Individual lobes showed a fluctuating pattern of radial growth from month to month with alternating periods of fast and slow growth. Monthly variations in radial growth of different lobes were synchronized in some but not in all thalli. Few significant correlations were found between the radial growth of individual lobes and total monthly rainfall or shortwave radiation. The levels of ribitol, arabitol and mannitol were measured in individual lobes. All three polyols varied significantly between lobes within a thallus suggesting that variations in algal phostosynthesis and in the partitioning of fungal polyols may contribute to lobe growth variation. The effect on thallus symmetry of lobes which grew radially either consistently faster or slower than average was studied. Slow growing lobes were overgrown, and gaps in the perimeter were eliminated by the growth of neighbouring lobes, in approximately 7 to 9 months. However, a rapidly growing lobe, with its neighbours removed on either side, continued to grow radially at the same rate as rapidly growing control lobes. The results suggested that lobe growth variation results from a combination of factors which may include the origin of the lobes, lobe morphology and the patterns of algal cell division and hyphal elongation in different lobes. No convincing evidence was found to suggest that exchange of carbohydrate occurred between lobes which would tend to equalize their radial growth. Hence, the fluctuating pattern of lobe growth observed may be sufficient to maintain a degree of symmetry in most thalli. In addition, slow growing lobes would tend to be overgrown by faster growing neighbours thus preventing the formation of indentations in the thallus perimeter.

Test of a mediation model of perceived organisational support

This study examined the mediating influence of trust in organization (TIO) and organization-based self-esteem (OBSE) on the relationship between perceived organization support (POS) and its work outcomes. Data were obtained from employee–supervisor dyads from multiple organizations located in a major city in southern China. Structural equation modeling results revealed that: (a) POS related to TIO and OBSE and (b) TIO and OBSE fully mediated the relationship between POS and the work outcomes of organizational commitment and in-role performance, but partially mediated the POS–organizational citizenship behavior relationship.

Antecedents and outcomes of abusive supervision:test of a trickle-down model

The authors examined antecedents of abusive supervision and the relative importance of interactional and procedural justice as mediators of the relationship between abusive supervision and the work outcomes of affective organizational commitment and individual- and organization-directed citizenship behaviors. Data were obtained from subordinate-supervisor dyads from a telecommunication company located in southeastern China. Results of moderated regression analysis revealed that authoritarian leadership style moderated the relationship between supervisors' perceptions of interactional justice and abusive supervision such that the relationship was stronger for supervisors high rather than low in authoritarian leadership style. In addition, results of structural equation modeling analysis revealed that subordinates' perceptions of interactional but not procedural justice fully mediated the relationship between abusive supervision and the work outcomes. Implications for future investigations of abusive supervision are discussed. Copyright 2007 by the American Psychological Association.

Countering the trend towards careerist orientation in the age of downsizing:test of a social exchange model

Predicated on the assumption that employee careerist orientation resulting from organizational actions to cut costs constitutes a potential threat to their long-term profitability and success, this study proposed and tested a social exchange model of careerist orientation in the People's Republic of China. Specifically, it was hypothesized that organizational justice and career growth opportunities will be related to careerist orientation, but the relationship will be mediated by trust in employer. Structural equation modeling results provided support for the model. Trust in organization fully mediated the relationship between careerist orientation and its antecedents.

Human resource management systems and organizational performance:a test of a mediating model in the Greek manufacturing context

This paper investigates the relationship between systems of HRM policies and organizational performance. The research is based on a sample of 178 organizations operating in the Greek manufacturing sector. A mediation model is tested to examine the link between HRM and organizational performance. The results of this study support the hypothesis that the relationship between the HRM systems of resourcing-development and reward-relations, and organizational performance, is mediated through the HRM outcomes of skills and attitudes. The paper not only supports the theory that HRM systems have a positive impact on organizational performance but also explains the mechanisms through which HRM systems improve organizational performance.

Trust as a mediator of the relationship between organizational justice and work outcomes:test of a social exchange model

Data obtained from full-time employees of a public sector organization in India were used to test a social exchange model of employee work attitudes and behaviors. LISREL results revealed that whereas the three organizational justice dimensions (distributive, procedural and interactional) were related to trust in organization only interactional justice was related to trust in supervisor. The results further revealed that relative to the hypothesized fully mediated model a partially mediated model better fitted the data. Trust in organization partially mediated the relationship between distributive and procedural justice and the work attitudes of job satisfaction, turnover intentions, and organizational commitment but fully mediated the relationship between interactional justice and these work attitudes. In contrast, trust in supervisor fully mediated the relationship between interactional justice and the work behaviors of task performance and the individually- and organizationally-oriented dimensions of citizenship behavior.

A test of basic assumptions of Affective Events Theory (AET) in call centre work

Based on data from 2091 call centre representatives working in 85 call centres in the UK, central assumptions of affective events theory (AET) are tested. AET predicts that specific features of work (e.g. autonomy) have an impact on the arousal of emotions and moods at work that, in turn, co-determine job satisfaction of employees. AET further proposes that job satisfaction is an evaluative judgement that mainly explains cognitive-based behaviour, whereas emotions and moods better predict affective-based behaviour. The results support these assumptions. A clear separation of key constructs (job satisfaction, positive and negative emotions) was possible. Moreover, correlations between several work features (e.g. supervisory support) and job satisfaction were, in part, mediated by work emotions, even when controlling for gender, age, call centre type (in-house versus outsourced centres) and call centre size. Predictions regarding consequences of satisfaction and affect were partly corroborated as continuance commitment was more strongly related to job satisfaction than to positive emotions. In addition, affective commitment and health complaints were related to both emotions and job satisfaction to the same extent. Thus, AET is a fruitful framework for explaining why and how specific management strategies used for designing work features influence important organizational attitudes and well-being of employees. © 2006 British Academy of Management.

Mach edges: a critical test of the nonlinear 3rd derivative model for edge-detection

Feature detection is a crucial stage of visual processing. In previous feature-marking experiments we found that peaks in the 3rd derivative of the luminance profile can signify edges where there are no 1st derivative peaks nor 2nd derivative zero-crossings (Wallis and George 'Mach edges' (the edges of Mach bands) were nicely predicted by a new nonlinear model based on 3rd derivative filtering. As a critical test of the model, we now use a new class of stimuli, formed by adding a linear luminance ramp to the blurred triangle waves used previously. The ramp has no effect on the second or higher derivatives, but the nonlinear model predicts a shift from seeing two edges to seeing only one edge as the added ramp gradient increases. In experiment 1, subjects judged whether one or two edges were visible on each trial. In experiment 2, subjects used a cursor to mark perceived edges and bars. The position and polarity of the marked edges were close to model predictions. Both experiments produced the predicted shift from two to one Mach edge, but the shift was less complete than predicted. We conclude that the model is a useful predictor of edge perception, but needs some modification.

To link or not to link: a test of the case linkage principles using serial car theft data

The purpose of the present study is to test the case linkage principles of behavioural consistency and behavioural distinctiveness using serial vehicle theft data. Data from 386 solved vehicle thefts committed by 193 offenders were analysed using Jaccard's, regression and Receiver Operating Characteristic analyses to determine whether objectively observable aspects of crime scene behaviour could be used to distinguish crimes committed by the same offender from those committed by different offenders. The findings indicate that spatial behaviour, specifically the distance between theft locations and between dump locations, is a highly consistent and distinctive aspect of vehicle theft behaviour; thus, intercrime and interdump distance represent the most useful aspects of vehicle theft for the purpose of case linkage analysis. The findings have theoretical and practical implications for understanding of criminal behaviour and for the development of decision-support tools to assist police investigation and apprehension of serial vehicle theft offenders.