Investigating behavioral antecedents of turnover at three job tenure levels.

A field study was conducted to investigate differences between hourly assembly operators who stayed and hourly assembly operators who voluntarily quit their jobs. A total of 80 stayers and 121 leavers were identified from personnel records and were classified into one of three job tenure groups, 2–5 months, 6–12 months, and more than 12 months. Job performance, attendance measures, and biographical variables were used to predict turnover for each job tenure group. Results indicated poorer performance by leavers with 6–22 months tenure compared with stayers. No differences in performance or attendance were obtained between stayers and leavers with between 2–5 months and those with more than 12-months job tenure. Leavers after 6 and before 12 months demonstrated more absenteeism compared with stayers. Implications for the role of absenteeism and constraints on the performance-retention relation are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of paper sheet fiber orientation distributions by a laser optical diffraction method

The combination of the laser and optical diffraction analysis provides a powerful tool for the determination of fiber orientation distribution in any paper sheet of basis weight low enough to be translucent to the laser beam. The coherent light beam from the laser is diffracted by the sample. It undergoes a Fourier transform from which the orientation distributions can be calculated. Measurements were made on 14 different samples of various degrees of orientation, including an essentially random handsheet as a control. The cross-direction/machine direction elastic modulus ratios of the samples were found to correlate well with the distribution functions fitted to the orientation data. The correlation curve was S-shaped, with a drastic drop in the modulus ration in the medium range of fiber orientation.     

How do we read algorithms? A case study

The authors report on an experiment that explored the way subjects view an algorithm, written in Pascal, and the graphical representation of its behavior. They designed the experiment to examine the influence of programming experience on how subjects view a short but complex algorithm, and they analyzed the scan patterns of eye movement for subjects at two experience levels. They describe the experimental procedure in detail, and discuss the results. An important finding was that all subjects needed numerous fixations in most areas of the algorithm and spent more time viewing relevant slide areas than did subjects in studies using simple text. This supports the hypothesis that viewing strategies for algorithms differ from those for prose     

Posttraumatic stress disorder in substance abuse patients: Relationship to 1-year posttreatment outcomes.

140 men with posttraumatic stress disorder (PTSD) and substance abuse (SA-PTSD) were compared with 1,166 men with only SA (SA-only) and 227 men with SA and Axis I psychiatric diagnoses other than PTSD (SA-PSY) on substance-related and psychosocial outcomes 1 yr after VA inpatient SA treatment. At follow-up, SA-PTSD patients reported more problems that directly resulted from SA, had more psychological distress, and reported less support from friends than both SA-only and SA-PSY patients. SA-PTSD patients were less likely to be employed and more likely to be readmitted for inpatient/residential treatment during the follow-up than SA-only patients. The effect of PTSD on 1-yr problems from SA was partially mediated by greater use of emotional discharge coping, having more positive expectancies regarding substance use, and expecting fewer benefits from quitting. Expecting fewer benefits from quitting partially explained the relationship between PTSD and 1-yr friend support. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In vivo mutational analysis of the mupirocin gene cluster reveals labile points in the biosynthetic pathway: the "leaky hosepipe" mechanism

A common feature of the mupirocin and other gene clusters of the AT-less polyketide synthase (PKS) family of metabolites is the introduction of carbon branches by a gene cassette that contains a beta-hydroxy-beta-methylglutaryl CoA synthase (HMC) homologue and acyl carrier protein (ACP), ketosynthase (KS) and two crotonase superfamily homologues. In vivo studies of Pseudomonas fluorescens strains in which any of these components have been mutated reveal a common phenotype in which the two major isolable metabolites are the truncated hexaketide mupirocin H and the tetraketide mupiric acid. The structure of the latter has been confirmed by stereoselective synthesis. Mupiric acid is also the major metabolite arising from inactivation of the ketoreductase (KR) domain of module 4 of the modular PKS. A number of other mutations in the tailoring region of the mupirocin gene cluster also result in production of both mupirocin H and mupiric acid. To explain this common phenotype we propose a mechanistic rationale in which both mupirocin H and mupiric acid represent the products of selective and spontaneous release from labile points in the pathway that occur at significant levels when mutations block the pathway either close to or distant from the labile points.     

Flower Inspiration: Broad-Angle Structural Color through Tunable Hierarchical Wrinkles in Thin Film Multilayers

The petals of some flowers form hierarchical structures when nano-scale cuticular ridges overlay bulged epidermal cells. These hierarchical structures can broaden the observable angles of iridescence. The resulting optical effect enhances the foraging efficiency of pollinators. Although efforts have been devoted to mimicking this unique broad-angle structural color, the intrinsic tunability offered by natural systems to control such a broadened spectrum is still absent in synthetic models. A hierarchical system is developed that provides hierarchical wrinkle-based structures that tune the observable angles for structural color. Laser diffraction measurements demonstrate that the observable angle of reflectance is broadened in proportion to the square root of the applied compressive strain. The morphology controls the diffraction pattern: the small wrinkles control the diffraction angles and the large wrinkles broaden the observable range. The development of a multi-mode wrinkling system to produce this broad-angle structural color only occurs within a limited range of conditions, which are experimentally discovered and theoretically modeled. Without diffractive small wrinkles, single wrinkling modes do not display structural colors. The control of wrinkling modes mimics the tunability of petals, which gives new insight into the natural system and provides a robust foundation for tunable structural color control.     

Smokers’ thoughts and worries: A study using ecological momentary assessment.

Objective: The purpose of this study was to investigate smokers’ thoughts and worries about their smoking behavior. Researchers have sometimes asked smokers to make such self-assessments but typically using retrospective summary judgments. Design: Using ecological momentary assessment, community and student smokers reported five times daily during two separate 1-week intervals. Main Outcome Measures: Smokers reported their thoughts about smoking, worries about smoking, and level of contemplation to quit smoking. Results: Smokers reported thinking negatively about their smoking 26.8% of the time they had a cigarette. The most frequent thoughts reported by smokers related to immediate reinforcement of smoking (e.g., “How I smell like cigarettes”). However, smokers reported more intense worry about thoughts related to health concerns (e.g., “Symptoms I'm having because of smoking”). The occurrence of negative thoughts was significantly and positively related to contemplation about quitting, worry about smoking, and risk perceptions. Finally, self-reported worry intensity was more strongly related to contemplation of quitting than negative thought occurrence. Conclusion: Our results show that thoughts about smoking (i.e., cognitions) and feelings about smoking (i.e., worry) are loosely connected and it is feelings rather than cognitions that are most related to contemplation to quit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phosphopantetheinylation and Specificity of Acyl Carrier Proteins in the Mupirocin Biosynthetic Cluster

Acyl carrier proteins are vital for the biosynthesis of fatty acids and polyketides. The mupirocin biosynthetic cluster of Pseudomonas fluorescens encodes eleven type I ACPs embedded in its multifunctional polyketide synthase (PKS) proteins plus five predicted type II ACPs (mAcpA‐E) that are known to be essential for mupirocin biosynthesis by deletion and complementation analysis. MupN is a putative Sfp‐type phosphopantetheinyl transferase. Overexpression of three type I and three type II mupirocin ACPs in Escherichia coli, with or without mupN, followed by mass spectroscopy revealed that MupN can modify both mupirocin type I and type II ACPs to their holo‐form. The endogenous phosphopantetheinyl transferase of E. coli modified mAcpA but not mAcpC or D. Overexpression of the type II ACPs in macp deletion mutants of the mupirocin producer P. fluorescens 10586 showed that they cannot substitute for each other while hybrids between mAcpA and mAcpB indicated that, at least for mAcpB, the C‐terminal domain determines functional specificity. Amino acid alignments identified mACPs A and D as having C‐terminal extensions. Mutation of these regions generated defective ACPs, the activity of which could be restored by overexpression of the macp genes on separate plasmids.     

Dehydriding and re-hydriding properties of high-energy ball milled LiBH4 + MgH2 mixtures

Here we report the first investigation of the dehydriding and re-hydriding properties of 2LiBH₄ + MgH₂ mixtures in the solid state. Such a study is made possible by high-energy ball milling of 2LiBH₄ + MgH₂ mixtures at liquid nitrogen temperature with the addition of graphite. The 2LiBH₄ + MgH₂ mixture ball milled under this condition exhibits a 5-fold increase in the released hydrogen at 265 °C when compared with ineffectively ball milled counterparts. Furthermore, both LiBH₄ and MgH₂ contribute to hydrogen release in the solid state. The isothermal dehydriding/re-hydriding cycles at 265 °C reveal that re-hydriding is dominated by re-hydriding of Mg. These unusual phenomena are explained based on the formation of nanocrystalline and amorphous phases, the increased defect concentration in crystalline compounds, and possible catalytic effects of Mg, MgH₂ and LiBH₄ on their dehydriding and re-hydriding properties.