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Sample records for rapid population turnover

  1. Rapid Gene Turnover as a Significant Source of Genetic Variation in a Recently Seeded Population of a Healthcare-Associated Pathogen

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    Lucía Graña-Miraglia

    2017-09-01

    Full Text Available Genome sequencing has been useful to gain an understanding of bacterial evolution. It has been used for studying the phylogeography and/or the impact of mutation and recombination on bacterial populations. However, it has rarely been used to study gene turnover at microevolutionary scales. Here, we sequenced Mexican strains of the human pathogen Acinetobacter baumannii sampled from the same locale over a 3 year period to obtain insights into the microevolutionary dynamics of gene content variability. We found that the Mexican A. baumannii population was recently founded and has been emerging due to a rapid clonal expansion. Furthermore, we noticed that on average the Mexican strains differed from each other by over 300 genes and, notably, this gene content variation has accrued more frequently and faster than the accumulation of mutations. Moreover, due to its rapid pace, gene content variation reflects the phylogeny only at very short periods of time. Additionally, we found that the external branches of the phylogeny had almost 100 more genes than the internal branches. All in all, these results show that rapid gene turnover has been of paramount importance in producing genetic variation within this population and demonstrate the utility of genome sequencing to study alternative forms of genetic variation.

  2. Rapid Gene Turnover as a Significant Source of Genetic Variation in a Recently Seeded Population of a Healthcare-Associated Pathogen.

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    Graña-Miraglia, Lucía; Lozano, Luis F; Velázquez, Consuelo; Volkow-Fernández, Patricia; Pérez-Oseguera, Ángeles; Cevallos, Miguel A; Castillo-Ramírez, Santiago

    2017-01-01

    Genome sequencing has been useful to gain an understanding of bacterial evolution. It has been used for studying the phylogeography and/or the impact of mutation and recombination on bacterial populations. However, it has rarely been used to study gene turnover at microevolutionary scales. Here, we sequenced Mexican strains of the human pathogen Acinetobacter baumannii sampled from the same locale over a 3 year period to obtain insights into the microevolutionary dynamics of gene content variability. We found that the Mexican A. baumannii population was recently founded and has been emerging due to a rapid clonal expansion. Furthermore, we noticed that on average the Mexican strains differed from each other by over 300 genes and, notably, this gene content variation has accrued more frequently and faster than the accumulation of mutations. Moreover, due to its rapid pace, gene content variation reflects the phylogeny only at very short periods of time. Additionally, we found that the external branches of the phylogeny had almost 100 more genes than the internal branches. All in all, these results show that rapid gene turnover has been of paramount importance in producing genetic variation within this population and demonstrate the utility of genome sequencing to study alternative forms of genetic variation.

  3. Human CD4+ CD25hi Foxp3+ regulatory T cells are derived by rapid turnover of memory populations in vivo

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    Vukmanovic-Stejic, Milica; Zhang, Yan; Cook, Joanne E.; Fletcher, Jean M.; McQuaid, Arthur; Masters, Joanne E.; Rustin, Malcolm H.A.; Taams, Leonie S.; Beverley, Peter C.L.; Macallan, Derek C.; Akbar, Arne N.

    2006-01-01

    While memory T cells are maintained by continuous turnover, it is not clear how human regulatory CD4+CD45RO+CD25hi Foxp3+ T lymphocyte populations persist throughout life. We therefore used deuterium labeling of cycling cells in vivo to determine whether these cells could be replenished by proliferation. We found that CD4+CD45RO+Foxp3+CD25hi T lymphocytes were highly proliferative, with a doubling time of 8 days, compared with memory CD4+CD45RO+Foxp3–CD25– (24 days) or naive CD4+CD45RA+Foxp3–CD25– populations (199 days). However, the regulatory population was susceptible to apoptosis and had critically short telomeres and low telomerase activity. It was therefore unlikely to be self regenerating. These data are consistent with continuous production from another population source. We found extremely close TCR clonal homology between regulatory and memory CD4+ T cells. Furthermore, antigen-related expansions within certain TCR Vβ families were associated with parallel numerical increases of CD4+CD45RO+CD25hiFoxp3+ Tregs with the same Vβ usage. It is therefore unlikely that all human CD4+CD25+Foxp3+ Tregs are generated as a separate functional lineage in the thymus. Instead, our data suggest that a proportion of this regulatory population is generated from rapidly dividing, highly differentiated memory CD4+ T cells; this has considerable implications for the therapeutic manipulation of these cells in vivo. PMID:16955142

  4. Measurement of proliferation and disappearance of rapid turnover cell populations in human studies using deuterium-labeled glucose.

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    Macallan, Derek C; Asquith, Becca; Zhang, Yan; de Lara, Catherine; Ghattas, Hala; Defoiche, Julien; Beverley, Peter C L

    2009-01-01

    Cell proliferation may be measured in vivo by quantifying DNA synthesis with isotopically labeled deoxyribonucleotide precursors. Deuterium-labeled glucose is one such precursor which, because it achieves high levels of enrichment for a short period, is well suited to the study of rapidly dividing cells, in contrast to the longer term labeling achieved with heavy water ((2)H(2)O). As deuterium is non-radioactive and glucose can be readily administered, this approach is suitable for clinical studies. It has been widely applied to investigate human lymphocyte proliferation, but solid tissue samples may also be analyzed. Rate, duration and route (intravenous or oral) of [6,6-(2)H(2)]-glucose administration should be adapted to the target cell of interest. For lymphocytes, cell separation is best achieved by fluorescence activated cell sorting (FACS), although magnetic bead separation is an alternative. DNA is then extracted, hydrolyzed enzymatically and analyzed by gas chromatography mass spectrometry (GC/MS). Appropriate mathematical modeling is critical to interpretation. Typical time requirements are as follows: labeling, 10-24 h; sampling, approximately 3 weeks; DNA extraction/derivatization, 2-3 d; and GC/MS analysis, approximately 2 d.

  5. Rapid turnover of glycogen in memory formation.

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    Gibbs, Marie E; Hutchinson, Dana S

    2012-11-01

    The influence of noradrenaline acting at α(2)-AR and β(2)-ARs on the turnover of glycogen after learning has been investigated. The role of glycogen turnover in memory formation was examined using weakly-reinforced, single trial bead discrimination training in day-old domestic chickens. This study follows our previous work that focused on the need for glycogen breakdown (glycogenolysis) during learning. Inhibition of glycogenolysis by 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) prevented the consolidation of strongly-reinforced learning and inhibited memory. The action of DAB could be prevented by stimulating glycogenolysis with the selective β(2)-AR agonist, zinterol. Stimulation of α(2)-ARs has been shown to lead to an increase in the turnover and synthesis of glycogen. In the present study, we examined the effect of inhibition of α(2)-AR stimulated glycogen turnover (measured as(14)C-glucose incorporation into glycogen) on the ability of zinterol to promote the consolidation of weakly reinforced memory. In astrocytes, the selective α(2)-AR agonist clonidine stimulated (14)C-glucose incorporation into glycogen in chick astrocytes and this was inhibited by the selective α(2)-AR antagonist, ARC239. The critical importance of the timing of ARC239 injection relative to training and intracerebral administration of zinterol was examined. It is concluded that our data provides evidence for a readily accessible labile pool of glycogen in brain astrocytes. If glycogen synthesis is inhibited, the can be depleted within 10 min, thus preventing zinterol from promoting consolidation.

  6. Coupled Proliferation and Apoptosis Maintain the Rapid Turnover of Microglia in the Adult Brain

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    Katharine Askew

    2017-01-01

    Full Text Available Microglia play key roles in brain development, homeostasis, and function, and it is widely assumed that the adult population is long lived and maintained by self-renewal. However, the precise temporal and spatial dynamics of the microglial population are unknown. We show in mice and humans that the turnover of microglia is remarkably fast, allowing the whole population to be renewed several times during a lifetime. The number of microglial cells remains steady from late postnatal stages until aging and is maintained by the spatial and temporal coupling of proliferation and apoptosis, as shown by pulse-chase studies, chronic in vivo imaging of microglia, and the use of mouse models of dysregulated apoptosis. Our results reveal that the microglial population is constantly and rapidly remodeled, expanding our understanding of its role in the maintenance of brain homeostasis.

  7. The rapid yet uneven turnover of Earth's groundwater

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    Befus, Kevin M.; Jasechko, Scott; Luijendijk, Elco; Gleeson, Tom; Bayani Cardenas, M.

    2017-06-01

    The turnover of groundwater through recharge drives many processes throughout Earth's surface and subsurface. Yet groundwater turnover rates and their relationship to regional climate and geology remain largely unknown. We estimated that over 200 × 106 km3 of groundwater has recharged since the Last Glacial Maximum (LGM), which is 10 times the volume of global groundwater storage. However, flushing is very unevenly distributed throughout Earth's one million watersheds, with some aquifers turned over thousands of times to others with global groundwater turnover of 5 ± 3 times since the LGM highlights groundwater's active role in Earth system processes. Incomplete groundwater turnover since the LGM beneath a third of land areas reveals the imprint of relict climate conditions on modern-day groundwater resources. The bulk groundwater turnover calculated here enables better quantification of groundwater's impact in dynamic global water budgets and the transport of nutrients, contaminants, and geologic weathering products.Plain Language SummaryThe duration groundwater spends in an aquifer sets how long it is sequestered from the rest of the hydrologic cycle, where it can interact with the surrounding matrix and transport dissolved chemicals to and from the land surface. Over geologic timescales, these interactions transform landscapes, affect global climate, and regulate water resource sustainability and quality. We present how much groundwater has recharged since the Last Glacial Maximum and where groundwater on Earth is associated with previous climate conditions.

  8. Estimating Population Turnover Rates by Relative Quantification Methods Reveals Microbial Dynamics in Marine Sediment.

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    Kevorkian, Richard; Bird, Jordan T; Shumaker, Alexander; Lloyd, Karen G

    2018-01-01

    The difficulty involved in quantifying biogeochemically significant microbes in marine sediments limits our ability to assess interspecific interactions, population turnover times, and niches of uncultured taxa. We incubated surface sediments from Cape Lookout Bight, North Carolina, USA, anoxically at 21°C for 122 days. Sulfate decreased until day 68, after which methane increased, with hydrogen concentrations consistent with the predicted values of an electron donor exerting thermodynamic control. We measured turnover times using two relative quantification methods, quantitative PCR (qPCR) and the product of 16S gene read abundance and total cell abundance (FRAxC, which stands for "fraction of read abundance times cells"), to estimate the population turnover rates of uncultured clades. Most 16S rRNA reads were from deeply branching uncultured groups, and ∼98% of 16S rRNA genes did not abruptly shift in relative abundance when sulfate reduction gave way to methanogenesis. Uncultured Methanomicrobiales and Methanosarcinales increased at the onset of methanogenesis with population turnover times estimated from qPCR at 9.7 ± 3.9 and 12.6 ± 4.1 days, respectively. These were consistent with FRAxC turnover times of 9.4 ± 5.8 and 9.2 ± 3.5 days, respectively. Uncultured Syntrophaceae , which are possibly fermentative syntrophs of methanogens, and uncultured Kazan-3A-21 archaea also increased at the onset of methanogenesis, with FRAxC turnover times of 14.7 ± 6.9 and 10.6 ± 3.6 days. Kazan-3A-21 may therefore either perform methanogenesis or form a fermentative syntrophy with methanogens. Three genera of sulfate-reducing bacteria, Desulfovibrio , Desulfobacter , and Desulfobacterium , increased in the first 19 days before declining rapidly during sulfate reduction. We conclude that population turnover times on the order of days can be measured robustly in organic-rich marine sediment, and the transition from sulfate-reducing to methanogenic conditions stimulates

  9. Rapid Turnover of Effector–Memory CD4+ T Cells in Healthy Humans

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    Macallan, Derek C.; Wallace, Diana; Zhang, Yan; de Lara, Catherine; Worth, Andrew T.; Ghattas, Hala; Griffin, George E.; Beverley, Peter C.L.; Tough, David F.

    2004-01-01

    Memory T cells can be divided into central–memory (TCM) and effector–memory (TEM) cells, which differ in their functional properties. Although both subpopulations can persist long term, it is not known whether they are maintained by similar mechanisms. We used in vivo labeling with deuterated glucose to measure the turnover of CD4+ T cells in healthy humans. The CD45R0+CCR7− TEM subpopulation was shown to have a rapid proliferation rate of 4.7% per day compared with 1.5% per day for CD45R0+CCR7+ TCM cells; these values are equivalent to average intermitotic (doubling) times of 15 and 48 d, respectively. In contrast, the CD45RA+CCR7+ naive CD4+ T cell population was found to be much longer lived, being labeled at a rate of only 0.2% per day (corresponding to an intermitotic time of approximately 1 yr). These data indicate that human CD4+ TEM cells constitute a short-lived cell population that requires continuous replenishment in vivo. PMID:15249595

  10. Invader or resident? Ancient-DNA reveals rapid species turnover in New Zealand little penguins.

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    Grosser, Stefanie; Rawlence, Nicolas J; Anderson, Christian N K; Smith, Ian W G; Scofield, R Paul; Waters, Jonathan M

    2016-02-10

    The expansion of humans into previously unoccupied parts of the globe is thought to have driven the decline and extinction of numerous vertebrate species. In New Zealand, human settlement in the late thirteenth century AD led to the rapid demise of a distinctive vertebrate fauna, and also a number of 'turnover' events where extinct lineages were subsequently replaced by closely related taxa. The recent genetic detection of an Australian little penguin (Eudyptula novaehollandiae) in southeastern New Zealand may potentially represent an additional 'cryptic' invasion. Here we use ancient-DNA (aDNA) analysis and radiocarbon dating of pre-human, archaeological and historical Eudyptula remains to reveal that the arrival of E. novaehollandiae in New Zealand probably occurred between AD 1500 and 1900, following the anthropogenic decline of its sister taxon, the endemic Eudyptula minor. This rapid turnover event, revealed by aDNA, suggests that native species decline can be masked by invasive taxa, and highlights the potential for human-mediated biodiversity shifts. © 2016 The Author(s).

  11. Segregation and rapid turnover of EDEM1 by an autophagy-like mechanism modulates standard ERAD and folding activities.

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    Calì, Tito; Galli, Carmela; Olivari, Silvia; Molinari, Maurizio

    2008-07-04

    EDEM1 is a crucial regulator of endoplasmic reticulum (ER)-associated degradation (ERAD) that extracts non-native glycopolypeptides from the calnexin chaperone system. Under normal growth conditions, the intralumenal level of EDEM1 must be low to prevent premature interruption of ongoing folding programs. We report that in unstressed cells, EDEM1 is segregated from the bulk ER into LC3-I-coated vesicles and is rapidly degraded. The rapid turnover of EDEM1 is regulated by a novel mechanism that shows similarities but is clearly distinct from macroautophagy. Cells with defective EDEM1 turnover contain unphysiologically high levels of EDEM1, show enhanced ERAD activity and are characterized by impaired capacity to efficiently complete maturation of model glycopolypeptides. We define as ERAD tuning the mechanisms operating in the mammalian ER at steady state to offer kinetic advantage to folding over disposal of unstructured nascent chains by selective and rapid degradation of ERAD regulators.

  12. Partial genetic turnover in neandertals: continuity in the East and population replacement in the West.

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    Dalén, Love; Orlando, Ludovic; Shapiro, Beth; Brandström-Durling, Mikael; Quam, Rolf; Gilbert, M Thomas P; Díez Fernández-Lomana, J Carlos; Willerslev, Eske; Arsuaga, Juan Luis; Götherström, Anders

    2012-08-01

    Remarkably little is known about the population-level processes leading up to the extinction of the neandertal. To examine this, we use mitochondrial DNA sequences from 13 neandertal individuals, including a novel sequence from northern Spain, to examine neandertal demographic history. Our analyses indicate that recent western European neandertals (48 kyr) European neandertals. Using control region sequences, Bayesian demographic simulations provide higher support for a model of population fragmentation followed by separate demographic trajectories in subpopulations over a null model of a single stable population. The most parsimonious explanation for these results is that of a population turnover in western Europe during early Marine Isotope Stage 3, predating the arrival of anatomically modern humans in the region.

  13. Interaction rewiring and the rapid turnover of plant-pollinator networks.

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    CaraDonna, Paul J; Petry, William K; Brennan, Ross M; Cunningham, James L; Bronstein, Judith L; Waser, Nickolas M; Sanders, Nathan J

    2017-03-01

    Whether species interactions are static or change over time has wide-reaching ecological and evolutionary consequences. However, species interaction networks are typically constructed from temporally aggregated interaction data, thereby implicitly assuming that interactions are fixed. This approach has advanced our understanding of communities, but it obscures the timescale at which interactions form (or dissolve) and the drivers and consequences of such dynamics. We address this knowledge gap by quantifying the within-season turnover of plant-pollinator interactions from weekly censuses across 3 years in a subalpine ecosystem. Week-to-week turnover of interactions (1) was high, (2) followed a consistent seasonal progression in all years of study and (3) was dominated by interaction rewiring (the reassembly of interactions among species). Simulation models revealed that species' phenologies and relative abundances constrained both total interaction turnover and rewiring. Our findings reveal the diversity of species interactions that may be missed when the temporal dynamics of networks are ignored. © 2017 John Wiley & Sons Ltd/CNRS.

  14. Bone turnover biomarkers and risk of osteoporotic hip fracture in an Asian population.

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    Dai, Zhaoli; Wang, Renwei; Ang, Li-Wei; Yuan, Jian-Min; Koh, Woon-Puay

    2016-02-01

    While epidemiologic studies suggest that bone turnover biomarkers may predict hip fracture risk, findings are inconsistent and Asian data are lacking. We conducted a matched case-control (1:1) study nested in the Singapore Chinese Health Study, a population-based prospective cohort of Chinese men and women (45-74years) recruited from 1993 to 1998 in Singapore. One hundred cases with incident hip fracture and 100 individually matched controls were randomly selected from 63,257 participants. Serum bone turnover biomarkers, namely bone alkaline phosphatase (bone ALP), osteocalcin (OC), procollagen type I N propeptide (PINP), N-terminal and C-terminal crosslinking telopeptide of type I collagen (NTX-I and CTX-I) were measured using immunoassays. Hip fracture cases had significantly higher serum levels of OC, PINP, CTX-I and NTX-I than controls (phip fracture (all Ps for trend≤0.006), where the risk was significantly increased by 4.32-8.23 folds for the respective BTM [Quartile (Q) 4 vs. Q1]. The odds ratio [OR (95% CI)] at the highest quartile (Q4) was 6.63 (2.02-21.18) for PINP and 4.92 (1.67-14.51) for CTX-I. The joint effect of PINP and CTX-I showed a 7-fold increase in risk (OR: 7.36; 95% CI: 2.53-21.41) comparing participants with higher levels of PINP (Q4) and CTX-I (Q3-Q4) to those with low levels of PINP (Q1-Q3) and CTX-I (Q1-Q2). Our data demonstrated that higher serum levels of bone turnover biomarkers were associated with increased risk of hip fracture in an Asian population. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Rapid Turnover of Cortical NCAM1 Regulates Synaptic Reorganization after Peripheral Nerve Injury

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    Hyoung-Gon Ko

    2018-01-01

    Full Text Available Peripheral nerve injury can induce pathological conditions that lead to persistent sensitized nociception. Although there is evidence that plastic changes in the cortex contribute to this process, the underlying molecular mechanisms are unclear. Here, we find that activation of the anterior cingulate cortex (ACC induced by peripheral nerve injury increases the turnover of specific synaptic proteins in a persistent manner. We demonstrate that neural cell adhesion molecule 1 (NCAM1 is one of the molecules involved and show that it mediates spine reorganization and contributes to the behavioral sensitization. We show striking parallels in the underlying mechanism with the maintenance of NMDA-receptor- and protein-synthesis-dependent long-term potentiation (LTP in the ACC. Our results, therefore, demonstrate a synaptic mechanism for cortical reorganization and suggest potential avenues for neuropathic pain treatment.

  16. Process inhomogeneity leads to rapid side product turnover in cultivation of Corynebacterium glutamicum

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    2014-01-01

    Background Corynebacterium glutamicum has large scale industrial applications in the production of amino acids and the potential to serve as a platform organism for new products. This means the demand for industrial process development is likely to increase. However, large scale cultivation conditions differ from laboratory bioreactors, mostly due to the formation of concentration gradients at the industrial scale. This leads to an oscillating supply of oxygen and nutrients for microorganisms with uncertain impact on metabolism. Scale-down bioreactors can be applied to study robustness and physiological reactions to oscillating conditions at a laboratory scale. Results In this study, C. glutamicum ATCC13032 was cultivated by glucose limited fed-batch cultivation in a two-compartment bioreactor consisting of an aerobic stirred tank and a connected non-aerated plug flow reactor with optional feeding. Continuous flow through both compartments generated oscillating profiles with estimated residence times of 45 and 87 seconds in the non-aerated plug flow compartment. Oscillation of oxygen supply conditions at substrate excess and oscillation of both substrate and dissolved oxygen concentration were compared to homogeneous reference cultivations. The dynamic metabolic response of cells within the anaerobic plug flow compartment was monitored throughout the processes, detecting high turnover of substrate into metabolic side products and acidification within oxygen depleted zones. It was shown that anaerobic secretion of lactate into the extracellular culture broth, with subsequent reabsorption in the aerobic glucose-limited environment, leads to mixed-substrate growth in fed-batch processes. Apart from this, the oscillations had only a minor impact on growth and intracellular metabolite characteristics. Conclusions Carbon metabolism of C. glutamicum changes at oscillating oxygen supply conditions, leading to a futile cycle over extracellular side products and back into

  17. Population priorities: the challenge of continued rapid population growth.

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    Turner, Adair

    2009-10-27

    Rapid population growth continues in the least developed countries. The revisionist case that rapid population could be overcome by technology, that population density was advantageous, that capital shallowing is not a vital concern and that empirical investigations had not proved a correlation between high population growth and low per capita income was both empirically and theoretically flawed. In the modern world, population density does not play the role it did in nineteenth-century Europe and rates of growth in some of today's least developed nations are four times than those in nineteenth-century Europe, and without major accumulation of capital per capita, no major economy has or is likely to make the low- to middle-income transition. Though not sufficient, capital accumulation for growth is absolutely essential to economic growth. While there are good reasons for objecting to the enforced nature of the Chinese one-child policy, we should not underestimate the positive impact which that policy has almost certainly had and will have over the next several decades on Chinese economic performance. And a valid reticence about telling developing countries that they must contain fertility should not lead us to underestimate the severely adverse impact of high fertility rates on the economic performance and prospects of many countries in Africa and the Middle East.

  18. Rapid turnover of DnaA at replication origin regions contributes to initiation control of DNA replication.

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    Schenk, Katrin; Hervás, Ana B; Rösch, Thomas C; Eisemann, Marc; Schmitt, Bernhard A; Dahlke, Stephan; Kleine-Borgmann, Luise; Murray, Seán M; Graumann, Peter L

    2017-02-01

    DnaA is a conserved key regulator of replication initiation in bacteria, and is homologous to ORC proteins in archaea and in eukaryotic cells. The ATPase binds to several high affinity binding sites at the origin region and upon an unknown molecular trigger, spreads to several adjacent sites, inducing the formation of a helical super structure leading to initiation of replication. Using FRAP analysis of a functional YFP-DnaA allele in Bacillus subtilis, we show that DnaA is bound to oriC with a half-time of 2.5 seconds. DnaA shows similarly high turnover at the replication machinery, where DnaA is bound to DNA polymerase via YabA. The absence of YabA increases the half time binding of DnaA at oriC, showing that YabA plays a dual role in the regulation of DnaA, as a tether at the replication forks, and as a chaser at origin regions. Likewise, a deletion of soj (encoding a ParA protein) leads to an increase in residence time and to overinitiation, while a mutation in DnaA that leads to lowered initiation frequency, due to a reduced ATPase activity, shows a decreased residence time on binding sites. Finally, our single molecule tracking experiments show that DnaA rapidly moves between chromosomal binding sites, and does not arrest for more than few hundreds of milliseconds. In Escherichia coli, DnaA also shows low residence times in the range of 200 ms and oscillates between spatially opposite chromosome regions in a time frame of one to two seconds, independently of ongoing transcription. Thus, DnaA shows extremely rapid binding turnover on the chromosome including oriC regions in two bacterial species, which is influenced by Soj and YabA proteins in B. subtilis, and is crucial for balanced initiation control, likely preventing fatal premature multimerization and strand opening of DnaA at oriC.

  19. Persistence of subclinical deformed wing virus infections in honeybees following Varroa mite removal and a bee population turnover.

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    Barbara Locke

    Full Text Available Deformed wing virus (DWV is a lethal virus of honeybees (Apis mellifera implicated in elevated colony mortality rates worldwide and facilitated through vector transmission by the ectoparasitic mite Varroa destructor. Clinical, symptomatic DWV infections are almost exclusively associated with high virus titres during pupal development, usually acquired through feeding by Varroa mites when reproducing on bee pupae. Control of the mite population, generally through acaricide treatment, is essential for breaking the DWV epidemic and minimizing colony losses. In this study, we evaluated the effectiveness of remedial mite control on clearing DWV from a colony. DWV titres in adult bees and pupae were monitored at 2 week intervals through summer and autumn in acaricide-treated and untreated colonies. The DWV titres in Apistan treated colonies was reduced 1000-fold relative to untreated colonies, which coincided with both the removal of mites and also a turnover of the bee population in the colony. This adult bee population turnover is probably more critical than previously realized for effective clearing of DWV infections. After this initial reduction, subclinical DWV titres persisted and even increased again gradually during autumn, demonstrating that alternative non-Varroa transmission routes can maintain the DWV titres at significant subclinical levels even after mite removal. The implications of these results for practical recommendations to mitigate deleterious subclinical DWV infections and improving honeybee health management are discussed.

  20. Protein turnover, amino acid requirements and recommendations for athletes and active populations.

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    Poortmans, J R; Carpentier, A; Pereira-Lancha, L O; Lancha Jr, A

    2012-10-01

    Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ((13)C-lysine, (15)N-glycine, ²H5-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g · kg(-1) · day(-1) compared to 0.8 g · kg(-1) · day(-1) in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

  1. Protein turnover, amino acid requirements and recommendations for athletes and active populations

    Energy Technology Data Exchange (ETDEWEB)

    Poortmans, J.R.; Carpentier, A. [Laboratory for Biometry and Sport Nutrition, Faculty of Motor Sciences, Free University of Brussels, Brussels (Belgium); Pereira-Lancha, L.O. [Departamento de Nutrição, Instituto Vita, São Paulo, SP (Brazil); Lancha, A. Jr. [Laboratório de Nutrição Aplicada à Atividade Motora, Escola de Educação Física e Esporte, Universidade de São Paulo, São Paulo, SP (Brazil)

    2012-06-08

    Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers ({sup 13}C-lysine, {sup 15}N-glycine, {sup 2}H{sub 5}-phenylalanine) and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes) compared to resistance exercise, which induces fiber hypertrophy (myofibrils). Nitrogen balance (difference between protein intake and protein degradation) for athletes is usually balanced when the intake of protein reaches 1.2 g·kg{sup −1}·day{sup −1} compared to 0.8 g·kg{sup −1}·day{sup −1} in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins) and carbohydrate (± 30 g maltodextrine) drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

  2. Protein turnover, amino acid requirements and recommendations for athletes and active populations

    Directory of Open Access Journals (Sweden)

    J.R. Poortmans

    2012-10-01

    Full Text Available Skeletal muscle is the major deposit of protein molecules. As for any cell or tissue, total muscle protein reflects a dynamic turnover between net protein synthesis and degradation. Noninvasive and invasive techniques have been applied to determine amino acid catabolism and muscle protein building at rest, during exercise and during the recovery period after a single experiment or training sessions. Stable isotopic tracers (13C-lysine, 15N-glycine, ²H5-phenylalanine and arteriovenous differences have been used in studies of skeletal muscle and collagen tissues under resting and exercise conditions. There are different fractional synthesis rates in skeletal muscle and tendon tissues, but there is no major difference between collagen and myofibrillar protein synthesis. Strenuous exercise provokes increased proteolysis and decreased protein synthesis, the opposite occurring during the recovery period. Individuals who exercise respond differently when resistance and endurance types of contractions are compared. Endurance exercise induces a greater oxidative capacity (enzymes compared to resistance exercise, which induces fiber hypertrophy (myofibrils. Nitrogen balance (difference between protein intake and protein degradation for athletes is usually balanced when the intake of protein reaches 1.2 g·kg-1·day-1 compared to 0.8 g·kg-1·day-1 in resting individuals. Muscular activities promote a cascade of signals leading to the stimulation of eukaryotic initiation of myofibrillar protein synthesis. As suggested in several publications, a bolus of 15-20 g protein (from skimmed milk or whey proteins and carbohydrate (± 30 g maltodextrine drinks is needed immediately after stopping exercise to stimulate muscle protein and tendon collagen turnover within 1 h.

  3. Rapid turnover of dissolved DMS and DMSP by defined bacterioplankton communities in the stratified euphotic zone of the North Sea

    Science.gov (United States)

    Zubkov, Mikhail V.; Fuchs, Bernhard M.; Archer, Stephen D.; Kiene, Ronald P.; Amann, Rudolf; Burkill, Peter H.

    Bacterioplankton-driven turnover of the algal osmolyte, dimethylsulphoniopropionate (DMSP), and its degradation product, dimethylsulphide (DMS) the major natural source of atmospheric sulphur, were studied during a Lagrangian SF 6-tracer experiment in the North Sea (60°N, 3°E). The water mass sampled within the euphotic zone was characterised by a surface mixed layer (from 0 m to 13-30 m) and a subsurface layer (from 13-30 m to 45-58 m) separated by a 2°C thermocline spanning 2 m. The fluxes of dissolved DMSP (DMSPd) and DMS were determined using radioactive tracer techniques. Rates of the simultaneous incorporation of 14C-leucine and 3H-thymidine were measured to estimate bacterioplankton production. Flow cytometry was employed to discriminate subpopulations and to determine the numbers and biomass of bacterioplankton by staining for nucleic acids and proteins. Bacterioplankton subpopulations were separated by flow cytometric sorting and their composition determined using 16S ribosomal gene cloning/sequencing and fluorescence in situ hybridisation with designed group-specific oligonucleotide probes. A subpopulation, dominated by bacteria related to Roseobacter-( α-proteobacteria), constituted 26-33% of total bacterioplankton numbers and 45-48% of biomass in both surface and subsurface layers. The other abundant prokaryotes were a group within the SAR86 cluster of γ-proteobacteria and bacteria from the Cytophaga-Flavobacterium—cluster. Bacterial consumption of DMSPd was greater in the subsurface layer (41 nM d -1) than in the surface layer (20 nM d -1). Bacterioplankton tightly controlled the DMSPd pool, particularly in the subsurface layer, with a turnover time of 2 h, whereas the turnover time of DMSPd in the surface layer was 10 h. Consumed DMSP satisfied the majority of sulphur demands of bacterioplankton, even though bacterioplankton assimilated only about 2.5% and 6.0% of consumed DMSPd sulphur in the surface and subsurface layers, respectively

  4. Rapid population increase in an introduced muskox population, West Greenland

    Directory of Open Access Journals (Sweden)

    Carsten Riis Olesen

    1993-10-01

    Full Text Available In 1962 and 1965, 27 (13 and 14 muskox yearlings were translocated from East Greenland (71°N to the Angujaartorfiup Nunaa range in West Greenland (67°N. Angujaartorfiup Nunaa is a 6600 km2 icefree, continental area where caribou are indigenous. The climate is strictly continental with a minimum of precipitation but with abundant vegetation. Aerial surveys in 1990 documented that the muskox population has increased to 2600 heads despite quota-based harvesting since 1988. The annual quota was 200, 300 and 400 for 1988, 1989 and 1990, respectively. Distribution of muskoxen shows a significant preference for low altitude habitats southeast of Kangerlussuaq Airport and around Arnangarnup Qoorua (Paradise valley. Annual population increment averages 30% and the calf crop is around 24% of the population. Yearling recruitment in the population reveals that calf mortality during winter is very limited. About half of the 1-year-old females are served and they eventually give birth to their first calf when they turn 2 years old. With half of the 2-year-old females reproducing, the calf/cow ration ranges between 0.9 and 1.0.

  5. Rapid cycling genomic selection in a multiparental tropical maize population

    Science.gov (United States)

    Genomic selection (GS) increases genetic gain by reducing the length of the selection cycle, as has been exemplified in maize using rapid cycling recombination of biparental populations. However, no results of GS applied to maize multi-parental populations have been reported so far. This study is th...

  6. Poverty Catchments: Migration, Residential Mobility, and Population Turnover in Impoverished Rural Illinois Communities

    Science.gov (United States)

    Foulkes, Matt; Newbold, K. Bruce

    2008-01-01

    Research has thoroughly documented how out-migration of the educated and skilled from rural areas leaves behind a poorer population and creates pockets of rural poverty. Recently, studies have recognized that the poor are also geographically mobile and that poverty migration patterns can reinforce rural poverty concentrations. In this process,…

  7. Rapid carbon turnover beneath shrub and tree vegetation is associated with low soil carbon stocks at a subarctic treeline.

    Science.gov (United States)

    Parker, Thomas C; Subke, Jens-Arne; Wookey, Philip A

    2015-05-01

    Climate warming at high northern latitudes has caused substantial increases in plant productivity of tundra vegetation and an expansion of the range of deciduous shrub species. However significant the increase in carbon (C) contained within above-ground shrub biomass, it is modest in comparison with the amount of C stored in the soil in tundra ecosystems. Here, we use a 'space-for-time' approach to test the hypothesis that a shift from lower-productivity tundra heath to higher-productivity deciduous shrub vegetation in the sub-Arctic may lead to a loss of soil C that out-weighs the increase in above-ground shrub biomass. We further hypothesize that a shift from ericoid to ectomycorrhizal systems coincident with this vegetation change provides a mechanism for the loss of soil C. We sampled soil C stocks, soil surface CO2 flux rates and fungal growth rates along replicated natural transitions from birch forest (Betula pubescens), through deciduous shrub tundra (Betula nana) to tundra heaths (Empetrum nigrum) near Abisko, Swedish Lapland. We demonstrate that organic horizon soil organic C (SOCorg ) is significantly lower at shrub (2.98 ± 0.48 kg m(-2) ) and forest (2.04 ± 0.25 kg m(-2) ) plots than at heath plots (7.03 ± 0.79 kg m(-2) ). Shrub vegetation had the highest respiration rates, suggesting that despite higher rates of C assimilation, C turnover was also very high and less C is sequestered in the ecosystem. Growth rates of fungal hyphae increased across the transition from heath to shrub, suggesting that the action of ectomycorrhizal symbionts in the scavenging of organically bound nutrients is an important pathway by which soil C is made available to microbial degradation. The expansion of deciduous shrubs onto potentially vulnerable arctic soils with large stores of C could therefore represent a significant positive feedback to the climate system. © 2014 John Wiley & Sons Ltd.

  8. Rapid Population Growth and its Implication for Malawi

    African Journals Online (AJOL)

    Worldwide concern has recently focused on the negative aspects of rapid population growth for the' future as regards natural and non-renewable re- sources, energy and the environment. A United. Nations sponsored international conference on. "Environment and Development" was held in Brazil. inJune 1992 to focus ...

  9. G1 cyclin degradation: the PEST motif of yeast Cln2 is necessary, but not sufficient, for rapid protein turnover.

    OpenAIRE

    Salama, S R; Hendricks, K B; Thorner, J

    1994-01-01

    The 545-residue Cln2 protein, like the other G1 cyclins of Saccharomyces cerevisiae, is a very unstable protein. This instability is thought to play a critical role in regulating cell cycle progression. The carboxyl-terminal domains of Cln2 and the other G1 cyclins contain sequences rich in Pro, Glu (and Asp), Ser, and Thr (so-called PEST motifs) that have been postulated to make up the signals that are responsible for the rapid degradation of these and other unstable proteins. To test this h...

  10. The statistics of genetic diversity in rapidly adapting populations.

    Science.gov (United States)

    Desai, Michael

    2013-03-01

    Evolutionary adaptation is driven by the accumulation of beneficial mutations, but the sequence-level dynamics of this process are poorly understood. The traditional view is that adaptation is dominated by rare beneficial ``driver'' mutations that occur sporadically and then rapidly increase in frequency until they fix (a ``selective sweep''). Yet in microbial populations, multiple beneficial mutations are often present simultaneously. Selection cannot act on each mutation independently, but only on linked combinations. This means that the fate of any mutation depends on a complex interplay between its own fitness effect, the genomic background in which it arises, and the rest of the sequence variation in the population. The balance between these factors determines which mutations fix, the patterns of sequence diversity within populations, and the degree to which evolution in replicate populations will follow parallel (or divergent) trajectories at the sequence level. Earlier work has uncovered signatures of these effects, but the dynamics of genomic sequence evolution in adapting microbial populations have not yet been directly observed. In this talk, I will describe how full-genome whole-population sequencing can be used to provide a detailed view of these dynamics at high temporal resolution over 1000 generations in 40 adapting Saccharomyces cerevisiaepopulations. This data shows how patterns of sequence evolution are driven by a balance between chance interference and hitchhiking effects, which increase stochastic variation in evolutionary outcomes, and the deterministic action of selection on individual mutations, which favors parallel solutions in replicate populations.

  11. Auxin induces exocytosis and the rapid synthesis of a high-turnover pool of plasma-membrane H(+)-ATPase.

    Science.gov (United States)

    Hager, A; Debus, G; Edel, H G; Stransky, H; Serrano, R

    1991-11-01

    Auxin causes elongation growth of plant cells by increasing the plastic extensibility of the cell wall. Putative cellular events involved in this hormone action were studied using maize (Zea mays L.) coleoptiles with the following results: (i) Auxin enhances membrane flow from the endoplasmic reticulum to the plasma membrane (PM). This effect was demonstrated by pulse-labeling of the endoplasmic reticulum with myo-[(3)H]inositol in coleoptile segments and by measuring the distribution of the label within isolated and separated microsomal membrane fractions, (ii) Auxin rapidly increases the amount of antibody-detectable H(+)-ATPase in the PM. This augmentation is already significant 10 min after the addition of indole-3-acetic acid (IAA) and reaches a new higher steady-state level after about 30 min. (iii) Cycloheximide, a potent inhibitor of both protein synthesis and extension growth, quickly diminishes the auxin-enhanced level of the PM H(+)-ATPase, indicating an apparent half-life of the enzyme of around 12 min. (iv) Cordycepin, which blocks the synthesis of mRNAs, reduces the auxin-elevated level of the H(+)-ATPase similar to cycloheximide. (v) Changes in the growth rate of coleoptile segments in response to IAA, cycloheximide, and cordycepin exactly reflect the changes of the H(+)-ATPase level in the PM. (vi) The elongation growth induced by fusicoccin, or ester compounds, or by an elevated CO2 concentration in the incubation medium, is not related to an increased number of H(+)-ATPase molecules within the PM. (vii) The necessity of H(+) for cell-wall-loosening processes is again demonstrated by growth experiments with abraded coleoptile segments. The adjustment of the cell wall to a pH of ≥6.5 completely abolishes the auxin-induced elongation growth; no inhibition occurs with non-abraded segments. Buffer solutions of pH ≤6.0 induce "acid growth" of abraded segments for several hours. It is suggested that auxin activates a cluster of genes responsible (i

  12. Psychosocial work environment, job mobility and gender differences in turnover behaviour: a prospective study among the Swedish general population.

    Science.gov (United States)

    Söderberg, Mia; Härenstam, Annika; Rosengren, Annika; Schiöler, Linus; Olin, Anna-Carin; Lissner, Lauren; Waern, Margda; Torén, Kjell

    2014-06-14

    Throughout the literature, substantial evidence supports associations between poor psychosocial work characteristics and a variety of ill-health outcomes. Yet, few reports strategies workers carry out to improve detrimental work conditions and consequently their health, such as changing jobs. The aim of this study was to examine if adverse psychosocial work exposure, as measured with the job demand-control and effort-reward imbalance models, could predict job mobility over a 5 years observation period. Participants were working men and women (n = 940; 54.3% women), aged 24-60 years from the population of Gothenburg and surrounding metropolitan area. Job demand-control and effort-reward variables were compared with independent t-tests and chi2-test in persons with and without job mobility. Multivariate logistic regression was used to analyse whether psychosocial factors could predict job mobility. All regression analyses were stratified by gender. Exposure to a combination of high demands-low control or high imbalance between effort and reward was related to increased odds of changing jobs (OR 1.63; CI 1.03-2.59 and OR 1.46; CI 1.13-1.89 respectively). When analysing men and women separately, men had a higher OR of changing jobs when exposed to either high demands-low control (OR 2.72; CI 1.24-5.98) or high effort-reward imbalance (OR 1.74; CI 1.11-2.72) compared to reference values. The only significant associations for women was slightly decreased odds for turnover in high reward jobs (OR 0.96; CI 0.92-0.99). The results indicate that workers will seek to improve poor work environment by changing jobs. There were notable gender differences, where men tended to engage in job mobility when exposed to adverse psychosocial factors, while women did not. The lack of measures for mechanisms driving job mobility was a limitation of this study, thus preventing conclusions regarding psychosocial factors as the primary source for job mobility.

  13. Rapid Cycling Genomic Selection in a Multiparental Tropical Maize Population

    Directory of Open Access Journals (Sweden)

    Xuecai Zhang

    2017-07-01

    Full Text Available Genomic selection (GS increases genetic gain by reducing the length of the selection cycle, as has been exemplified in maize using rapid cycling recombination of biparental populations. However, no results of GS applied to maize multi-parental populations have been reported so far. This study is the first to show realized genetic gains of rapid cycling genomic selection (RCGS for four recombination cycles in a multi-parental tropical maize population. Eighteen elite tropical maize lines were intercrossed twice, and self-pollinated once, to form the cycle 0 (C0 training population. A total of 1000 ear-to-row C0 families was genotyped with 955,690 genotyping-by-sequencing SNP markers; their testcrosses were phenotyped at four optimal locations in Mexico to form the training population. Individuals from families with the best plant types, maturity, and grain yield were selected and intermated to form RCGS cycle 1 (C1. Predictions of the genotyped individuals forming cycle C1 were made, and the best predicted grain yielders were selected as parents of C2; this was repeated for more cycles (C2, C3, and C4, thereby achieving two cycles per year. Multi-environment trials of individuals from populations C0, C1, C2, C3, and C4, together with four benchmark checks were evaluated at two locations in Mexico. Results indicated that realized grain yield from C1 to C4 reached 0.225 ton ha−1 per cycle, which is equivalent to 0.100 ton ha−1 yr−1 over a 4.5-yr breeding period from the initial cross to the last cycle. Compared with the original 18 parents used to form cycle 0 (C0, genetic diversity narrowed only slightly during the last GS cycles (C3 and C4. Results indicate that, in tropical maize multi-parental breeding populations, RCGS can be an effective breeding strategy for simultaneously conserving genetic diversity and achieving high genetic gains in a short period of time.

  14. Cryptic population dynamics: rapid evolution masks trophic interactions.

    Science.gov (United States)

    Yoshida, Takehito; Ellner, Stephen P; Jones, Laura E; Bohannan, Brendan J M; Lenski, Richard E; Hairston, Nelson G

    2007-09-01

    Trophic relationships, such as those between predator and prey or between pathogen and host, are key interactions linking species in ecological food webs. The structure of these links and their strengths have major consequences for the dynamics and stability of food webs. The existence and strength of particular trophic links has often been assessed using observational data on changes in species abundance through time. Here we show that very strong links can be completely missed by these kinds of analyses when changes in population abundance are accompanied by contemporaneous rapid evolution in the prey or host species. Experimental observations, in rotifer-alga and phage-bacteria chemostats, show that the predator or pathogen can exhibit large-amplitude cycles while the abundance of the prey or host remains essentially constant. We know that the species are tightly linked in these experimental microcosms, but without this knowledge, we would infer from observed patterns in abundance that the species are weakly or not at all linked. Mathematical modeling shows that this kind of cryptic dynamics occurs when there is rapid prey or host evolution for traits conferring defense against attack, and the cost of defense (in terms of tradeoffs with other fitness components) is low. Several predictions of the theory that we developed to explain the rotifer-alga experiments are confirmed in the phage-bacteria experiments, where bacterial evolution could be tracked. Modeling suggests that rapid evolution may also confound experimental approaches to measuring interaction strength, but it identifies certain experimental designs as being more robust against potential confounding by rapid evolution.

  15. Cryptic population dynamics: rapid evolution masks trophic interactions.

    Directory of Open Access Journals (Sweden)

    Takehito Yoshida

    2007-09-01

    Full Text Available Trophic relationships, such as those between predator and prey or between pathogen and host, are key interactions linking species in ecological food webs. The structure of these links and their strengths have major consequences for the dynamics and stability of food webs. The existence and strength of particular trophic links has often been assessed using observational data on changes in species abundance through time. Here we show that very strong links can be completely missed by these kinds of analyses when changes in population abundance are accompanied by contemporaneous rapid evolution in the prey or host species. Experimental observations, in rotifer-alga and phage-bacteria chemostats, show that the predator or pathogen can exhibit large-amplitude cycles while the abundance of the prey or host remains essentially constant. We know that the species are tightly linked in these experimental microcosms, but without this knowledge, we would infer from observed patterns in abundance that the species are weakly or not at all linked. Mathematical modeling shows that this kind of cryptic dynamics occurs when there is rapid prey or host evolution for traits conferring defense against attack, and the cost of defense (in terms of tradeoffs with other fitness components is low. Several predictions of the theory that we developed to explain the rotifer-alga experiments are confirmed in the phage-bacteria experiments, where bacterial evolution could be tracked. Modeling suggests that rapid evolution may also confound experimental approaches to measuring interaction strength, but it identifies certain experimental designs as being more robust against potential confounding by rapid evolution.

  16. Population coding in area V4 during rapid shape detections

    Science.gov (United States)

    Weiner, Katherine F.

    2015-01-01

    While previous studies have suggested that neuronal correlations are common in visual cortex over a range of timescales, the effect of correlations on rapid visually based decisions has received little attention. We trained Macaca mulatta to saccade to a peripherally presented shape embedded in dynamic noise as soon as the shape appeared. While the monkeys performed the task, we recorded from neuronal populations (5–29 cells) using a microelectrode array implanted in area V4, a visual area thought to be involved in form perception. While modest correlations were present between cells during visual stimulation, their magnitude did not change significantly subsequent to the appearance of a shape. We quantified the reliability and temporal precision with which neuronal populations signaled the appearance of the shape and predicted the animals' choices using mutual information analyses. To study the impact of correlations, we shuffled the activity from each cell across observations while retaining stimulus-dependent modulations in firing rate. We found that removing correlations by shuffling across trials minimally affected the reliability or timing with which pairs, or larger groups of cells, signaled the presence of a shape. To assess the downstream impact of correlations, we also studied how shuffling affected the ability of V4 populations to predict behavioral choices. Surprisingly, shuffling created a modest increase in the accuracy of such predictions, suggesting that the reliability of downstream neurons is slightly compromised by activity correlations. Our findings are consistent with neuronal correlations having a minimal effect on the reliability and timing of rapid perceptual decisions. PMID:25787961

  17. Rapid adjustment in chrysanthemum carbohydrate turnover and growth activity to a change in time-of-day application of light and daylength

    DEFF Research Database (Denmark)

    Kjær, Katrine Heinsvig; Poiré, Richard; Ottosen, Carl-Otto

    2012-01-01

    diurnally-regulated parameters related to growth. In this study, chrysanthemum plants were exposed to a change in the time-of-day application of light followed by short days or long days with a night interruption of light. We observed a clear shift in the diel cycle of sucrose turnover and relative leaf...

  18. Bone turnover and metabolism in patients with early multiple sclerosis and prevalent bone mass deficit: a population-based case-control study.

    Directory of Open Access Journals (Sweden)

    Stine Marit Moen

    Full Text Available BACKGROUND: Low bone mass is prevalent in ambulatory multiple sclerosis (MS patients even shortly after clinical onset. The mechanism is not known, but could involve shared etiological risk factors between MS and low bone mass such as hypovitaminosis D operating before disease onset, or increased bone loss after disease onset. The aim of this study was to explore the mechanism of the low bone mass in early-stage MS patients. METHODOLOGY/PRINCIPAL FINDINGS: We performed a population-based case-control study comparing bone turnover (cross-linked N-terminal telopeptide of type 1 collagen; NTX, bone alkaline phosphatase; bALP, metabolism (25-hydroxy- and 1, 25-dihydroxyvitamin D, calcium, phosphate, and parathyroid hormone, and relevant lifestyle factors in 99 patients newly diagnosed with clinically isolated syndrome (CIS or MS, and in 159 age, sex, and ethnicity matched controls. After adjustment for possible confounders, there were no significant differences in NTX (mean 3.3; 95% CI -6.9, 13.5; p = 0.519, bALP (mean 1.6; 95% CI -0.2, 3.5; p = 0.081, or in any of the parameters related to bone metabolism in patients compared to controls. The markers of bone turnover and metabolism were not significantly correlated with bone mass density, or associated with the presence of osteoporosis or osteopenia within or between the patient and control groups. Intake of vitamin D and calcium, reported UV exposure, and physical activity did not differ significantly. CONCLUSIONS/SIGNIFICANCE: Bone turnover and metabolism did not differ significantly in CIS and MS patients with prevalent low bone mass compared to controls. These findings indicate that the bone deficit in patients newly diagnosed with MS and CIS is not caused by recent acceleration of bone loss, and are compatible with shared etiological factors between MS and low bone mass.

  19. KECENDERUNGAN KEPUASAN KERJA SEBAGAI TRIGGER TURNOVER

    Directory of Open Access Journals (Sweden)

    Raditya Adi Saputra

    2017-06-01

    Full Text Available The purpose of this study are: (1 To determine the effect of job satisfaction on turnover intention; (2 To determine the effect of work stress on turnover intention; (3 To determine the effect of compensation on turnover intention; (4 To determine the effect of organizational climate on turnover intention; and (5 To determine the stress of work, compensation, organizational climate and job satisfaction effect on turnover intention. The population in this study are employees of the Cooperative KOKAPURA AVIA totaling 180 people, while employees who have worked more than three years as many as 128 people. Samples were taken 97 people. The technique of collecting data using questionnaires. The analysis used is multiple regression analysis and path analysis using PLS 3.0 Smart program. Based on the results of the study concluded that: (1 Job satisfaction significantly influence employee turnover intention; (2 Work stress significantly influence employee turnover intention; (3 Compensation incentives significantly influence employee turnover intention; (4 organizational climate significantly influence employee turnover intention; and (5 Work stress, incentive compensation, organizational climate and job satisfaction simultaneously significantly influence employee turnover intention.

  20. The Rapid Reproducers Paradox: Population Control and Individual Procreative Rights

    NARCIS (Netherlands)

    Wissenburg, M.L.J.

    1998-01-01

    In this article, I consider the impact of population policies on individual rights (in a very broad sense of the word), a topic that has received disproportionately little attention in debates on the legitimacy of population rights. I first concentrate on arguments in favour of very radical

  1. Communication and The Challenges of Rapid Population Growth in ...

    African Journals Online (AJOL)

    These factors include religious beliefs, customs and traditions, among others. The discourse also examined the various communication types in Africa and their appropriateness in educating Africans and their governments on the need to control high rate of population growth. Ironically, medical facilities available in African ...

  2. Rapid three dimensional two photon neural population scanning.

    Science.gov (United States)

    Schuck, Renaud; Quicke, Peter; Copeland, Caroline; Garasto, Stefania; Annecchino, Luca A; Hwang, June Kyu; Schultz, Simon R

    2015-08-01

    Recording the activity of neural populations at high sampling rates is a fundamental requirement for understanding computation in neural circuits. Two photon microscopy provides one promising approach towards this. However, neural circuits are three dimensional, and functional imaging in two dimensions fails to capture the 3D nature of neural dynamics. Electrically tunable lenses (ETLs) provide a simple and cheap method to extend laser scanning microscopy into the relatively unexploited third dimension. We have therefore incorporated them into our Adaptive Spiral Scanning (SSA) algorithm, which calculates kinematically efficient scanning strategies using radially modulated spiral paths. We characterised the response of the ETL, incorporated its dynamics using MATLAB models of the SSA algorithm and tested the models on populations of Izhikevich neurons of varying size and density. From this, we show that our algorithms can theoretically at least achieve sampling rates of 36.2Hz compared to 21.6Hz previously reported for 3D scanning techniques.

  3. Rapid population growth and environmental degradation: ultimate versus proximate factors.

    Science.gov (United States)

    Shaw, R P

    1989-01-01

    This philosophical review of 2 arguments about responsibility for and solutions to environmental degradation concludes that both sides are correct: the ultimate and the proximal causes. Ultimate causes of pollution are defined as the technology responsible for a given type of pollution, such as burning fossil fuel; proximate causes are defined as situation-specific factors confounding the problem, such as population density or rate of growth. Commoner and others argue that developed countries with low or negative population growth rates are responsible for 80% of world pollution, primarily in polluting technologies such as automobiles, power generation, plastics, pesticides, toxic wastes, garbage, warfaring, and nuclear weapons wastes. Distortionary policies also contribute; examples are agricultural trade protection, land mismanagement, urban bias in expenditures, and institutional rigidity., Poor nations are responsible for very little pollution because poverty allows little waste or expenditures for polluting, synthetic technologies. The proximal causes of pollution include numbers and rate of growth of populations responsible for the pollution. Since change in the ultimate cause of pollution remains out of reach, altering the numbers of polluters can make a difference. Predictions are made for proportions of the world's total waste production, assuming current 1.6 tons/capita for developed countries and 0.17 tons/capita for developing countries. If developing countries grow at current rates and become more wealthy, they will be emitting half the world's waste by 2025. ON the other hand, unsustainable population growth goes along with inadequate investment in human capital: education, health, employment, infrastructure. The solution is to improve farming technologies in the 117 non-self-sufficient countries, fund development in the most unsustainable enclaves of growing countries, break institutionalized socio-political rigidity in these enclaves, and focus on

  4. Rapid and Sensitive Detection of BLAD in Cattle Population

    Directory of Open Access Journals (Sweden)

    Daniela Elena Ilie

    2014-05-01

    Full Text Available Bovine leukocyte adhesion deficiency (BLAD is an autosomal recessive disorder with negative impact on dairy cattle breeding. The molecular basis of BLAD is a single point mutation (A→G, resulting in a single amino acid substitution (aspartic acid → glycine at amino acid 128 in the adhesion molecule CD18. The object of this study was to establish a fast and sensitive molecular genotyping assay to detect BLAD carriers using high-resolution melting (HRM curve analysis. We tested animals with known genotypes for BLAD that were previously confirmed by PCR-RFLP method, and then examined the sensitivity of mutation detection using PCR followed by HRM curve analysis. BLAD carriers were readily detectable using HRM assay. Thus, the PCR-HRM genotyping method is a rapid, easily interpretable, reliable and cost-effective assay for BLAD mutant allele detection. This assay can be useful in cattle genotyping and genetic selection.

  5. Organisational Commitment, Job Satisfaction and Turnover ...

    African Journals Online (AJOL)

    This study investigated organisational commitment, job satisfaction and turnover intentions among records management personnel in Ondo State Civil Service, Akure, Nigeria. Simple random sampling technique was used to draw 240 subjects from a population size of 275 records management personnel.

  6. Rapid adaptive evolution in novel environments acts as an architect of population range expansion.

    Science.gov (United States)

    Szűcs, M; Vahsen, M L; Melbourne, B A; Hoover, C; Weiss-Lehman, C; Hufbauer, R A

    2017-12-19

    Colonization and expansion into novel landscapes determine the distribution and abundance of species in our rapidly changing ecosystems worldwide. Colonization events are crucibles for rapid evolution, but it is not known whether evolutionary changes arise mainly after successful colonization has occurred, or if evolution plays an immediate role, governing the growth and expansion speed of colonizing populations. There is evidence that spatial evolutionary processes can speed range expansion within a few generations because dispersal tendencies may evolve upwards at range edges. Additionally, rapid adaptation to a novel environment can increase population growth rates, which also promotes spread. However, the role of adaptive evolution and the relative contributions of spatial evolution and adaptation to expansion are unclear. Using a model system, red flour beetles (Tribolium castaneum), we either allowed or constrained evolution of populations colonizing a novel environment and measured population growth and spread. At the end of the experiment we assessed the fitness and dispersal tendency of individuals originating either from the core or edge of evolving populations or from nonevolving populations in a common garden. Within six generations, evolving populations grew three times larger and spread 46% faster than populations in which evolution was constrained. Increased size and expansion speed were strongly driven by adaptation, whereas spatial evolutionary processes acting on edge subpopulations contributed less. This experimental evidence demonstrates that rapid evolution drives both population growth and expansion speed and is thus crucial to consider for managing biological invasions and successfully introducing or reintroducing species for management and conservation.

  7. Evolution in an Afternoon: Rapid Natural Selection and Adaptation of Bacterial Populations

    Science.gov (United States)

    Delpech, Roger

    2009-01-01

    This paper describes a simple, rapid and low-cost technique for growing bacteria (or other microbes) in an environmental gradient, in order to determine the tolerance of the microbial population to varying concentrations of sodium chloride ions, and suggests how the evolutionary response of a microbial population to the selection pressure of the…

  8. MANAGEMENT OF PERSONNEL TURNOVER

    Directory of Open Access Journals (Sweden)

    Vyara Slavyanska

    2014-09-01

    Full Text Available Personnel turnover is a problem of great importance and increasing actuality for the business practice both on a world scale and in Bulgaria. This provokes a search of effective instruments for its management. The paper presents a summary of a monograph examining the specificity of personnel turnover management.

  9. Managing teacher turnover

    African Journals Online (AJOL)

    Erna Kinsey

    ticular those students who have also done well in Mathematics and. Physical Science ... ". This plea, in part, does address a concern over one of the consequences of teacher turnover, that is, teacher shortages. However, the situation regarding teacher turnover and attrition in. South Africa seems complex due a variety of ...

  10. High-Sequence Diversity and Rapid Virus Turnover Contribute to Higher Rates of Coreceptor Switching in Treatment-Experienced Subjects with HIV-1 Viremia.

    Science.gov (United States)

    Nedellec, Rebecca; Herbeck, Joshua T; Hunt, Peter W; Deeks, Steven G; Mullins, James I; Anton, Elizabeth D; Reeves, Jacqueline D; Mosier, Donald E

    2017-03-01

    Coreceptor switching from CCR5 to CXCR4 is common during chronic HIV-1 infection, but is even more common in individuals who have failed antiretroviral therapy (ART). Prior studies have suggested rapid mutation and/or recombination of HIV-1 envelope (env) genes during coreceptor switching. We compared the functional and genotypic changes in env of viruses from viremic subjects who had failed ART just before and after coreceptor switching and compared those to viruses from matched subjects without coreceptor switching. Analysis of multiple unique functional env clones from each subject revealed extensive diversity at both sample time points and rapid diversification of sequences during the 4-month interval in viruses from both 9 subjects with coreceptor switching and 15 control subjects. Only two subjects had envs with evidence of recombination. Three findings distinguished env clones from subjects with coreceptor switching from controls: (1) lower entry efficiency via CCR5; (2) longer V1/V2 regions; and (3), lower nadir CD4 T cell counts during prior years of infection. Most of these subjects harbored virus with lower replicative capacity associated with protease (PR) and/or reverse transcriptase inhibitor resistance mutations, and the extensive diversification tended to lead either to improved entry efficiency via CCR5 or the gain of entry function via CXCR4. These results suggest that R5X4 or X4 variants emerge from a diverse, low-fitness landscape shaped by chronic infection, multiple ART resistance mutations, the availability of target cells, and reduced entry efficiency via CCR5.

  11. Rapid differentiation of sexual signals in invasive toads: call variation among populations

    Science.gov (United States)

    Yasumiba, Kiyomi; Duffy, Richard L.; Parsons, Scott A.; Alford, Ross A.; Schwarzkopf, Lin

    2016-01-01

    Advertisement calls tend to differ among populations, based on morphological and environmental factors, or simply geographic distance, in many taxa. Invasive cane toads (Rhinella marina) were introduced to Australia in 1935 and their distribution has expanded at increasing rates over time. Rapid evolution occurred in morphological and behavioural characters that accelerate dispersal, but the effects of rapid expansion on sexual signals have not been examined. We collected advertisement calls from four populations of different ages since invasion, and analysed the geographic differentiation of seven call parameters. Our comparisons indicate that the calls of R. marina differ among Australian populations. The signal variation was not simply clinal with respect to population age, climate, or morphological differentiation. We suggest that selection on signalling among populations has been idiosyncratic and may reflect local female preferences or adaptation to environmental factors that are not clinal such as energy availability. PMID:27328666

  12. Rapid climate change did not cause population collapse at the end of the European Bronze Age.

    Science.gov (United States)

    Armit, Ian; Swindles, Graeme T; Becker, Katharina; Plunkett, Gill; Blaauw, Maarten

    2014-12-02

    The impact of rapid climate change on contemporary human populations is of global concern. To contextualize our understanding of human responses to rapid climate change it is necessary to examine the archeological record during past climate transitions. One episode of abrupt climate change has been correlated with societal collapse at the end of the northwestern European Bronze Age. We apply new methods to interrogate archeological and paleoclimate data for this transition in Ireland at a higher level of precision than has previously been possible. We analyze archeological (14)C dates to demonstrate dramatic population collapse and present high-precision proxy climate data, analyzed through Bayesian methods, to provide evidence for a rapid climatic transition at ca. 750 calibrated years B.C. Our results demonstrate that this climatic downturn did not initiate population collapse and highlight the nondeterministic nature of human responses to past climate change.

  13. Temporal relationship between serum adipokines, biomarkers of bone and cartilage turnover, and cartilage volume loss in a population with clinical knee osteoarthritis.

    Science.gov (United States)

    Berry, Patricia A; Jones, Simon W; Cicuttini, Flavia M; Wluka, Anita E; Maciewicz, Rose A

    2011-03-01

    The association of obesity with both hand and knee osteoarthritis (OA) is suggestive of a link between dysfunctional metabolism and joint integrity. Given the role of adipokines in mediating bone and cartilage homeostasis, we undertook this study to examine the relationship between adipokines and bone and cartilage biomarkers in a population of subjects with OA, and to determine whether adipokine levels predicted 2-year cartilage integrity. One hundred seventeen subjects underwent magnetic resonance imaging at baseline and at 2-year followup. Cartilage volume was assessed from these images. Serum adipokine levels were measured at baseline. Bone and cartilage biomarker levels were measured at baseline and at 2-year followup. Linear regression was used to examine the relationship between baseline levels of adipokines and adipokine receptors (leptin, soluble leptin receptor [sOB-Rb], resistin, and adiponectin) and changes in levels of bone biomarkers (osteocalcin, N-terminal type I procollagen propeptide [PINP], C-terminal crosslinking telopeptide of type I collagen, N-terminal crosslinking telopeptide of type I collagen, or C-terminal crosslinking telopeptide of type I collagen generated by matrix metalloproteinases), levels of cartilage biomarkers (cartilage oligomeric matrix protein, N-terminal type IIA procollagen propeptide [PIIANP], or C2C), cartilage defects score, and cartilage volume over 2 years. Baseline leptin was associated with increased levels of bone formation biomarkers (osteocalcin and PINP) over 2 years, while sOB-Rb was associated with reduced levels of osteocalcin. Baseline sOB-Rb was associated with reduced levels of the cartilage formation biomarker PIIANP, an increased cartilage defects score, and increased cartilage volume loss over 2 years. All results were independent of age, sex, and body mass index. The findings of this study support the concept that serum adipokines may provide a nonmechanical link between obesity and joint integrity

  14. Rapid evolution leads to differential population dynamics and top-down control in resurrectedDaphniapopulations.

    Science.gov (United States)

    Goitom, Eyerusalem; Kilsdonk, Laurens J; Brans, Kristien; Jansen, Mieke; Lemmens, Pieter; De Meester, Luc

    2018-01-01

    There is growing evidence of rapid genetic adaptation of natural populations to environmental change, opening the perspective that evolutionary trait change may subsequently impact ecological processes such as population dynamics, community composition, and ecosystem functioning. To study such eco-evolutionary feedbacks in natural populations, however, requires samples across time. Here, we capitalize on a resurrection ecology study that documented rapid and adaptive evolution in a natural population of the water flea Daphnia magna in response to strong changes in predation pressure by fish, and carry out a follow-up mesocosm experiment to test whether the observed genetic changes influence population dynamics and top-down control of phytoplankton. We inoculated populations of the water flea D. magna derived from three time periods of the same natural population known to have genetically adapted to changes in predation pressure in replicate mesocosms and monitored both Daphnia population densities and phytoplankton biomass in the presence and absence of fish. Our results revealed differences in population dynamics and top-down control of algae between mesocosms harboring populations from the time period before, during, and after a peak in fish predation pressure caused by human fish stocking. The differences, however, deviated from our a priori expectations. An S-map approach on time series revealed that the interactions between adults and juveniles strongly impacted the dynamics of populations and their top-down control on algae in the mesocosms, and that the strength of these interactions was modulated by rapid evolution as it occurred in nature. Our study provides an example of an evolutionary response that fundamentally alters the processes structuring population dynamics and impacts ecosystem features.

  15. Rapid Point-of-Care Diagnostic Test for Syphilis in High-Risk Populations, Manaus, Brazil

    Science.gov (United States)

    Benzaken, Adele S.; de Andrade Rodrigues, Ệnio José; Mayaud, Philippe

    2009-01-01

    We assessed the acceptability and operational suitability of a rapid point-of-care syphilis test and identified barriers to testing among high-risk groups and healthcare professionals in a sexually transmitted infections clinic in Manaus, Brazil. Use of this test could considerably alleviate the impact of syphilis in hard-to-reach populations in the Amazon region of Brazil. PMID:19331762

  16. A Pilot Study of Rapid Hepatitis C Testing in Probation and Parole Populations in Rhode Island.

    Science.gov (United States)

    Zaller, Nickolas D; Patry, Emily J; Bazerman, Lauri B; Noska, Amanda; Kuo, Irene; Kurth, Ann; Beckwith, Curt G

    2016-01-01

    Hepatitis C virus (HCV) affects between five and seven million individuals in the United States and chronic infection can lead to liver disease, cirrhosis, and hepatocellular carcinoma. Probation/parole offices are a novel setting for rapid HCV testing, providing outreach to populations at increased risk for HCV infection and/or transmitting HCV to others. While some correctional facilities offer HCV testing, many individuals who present to probation/parole offices are never or briefly incarcerated and may not access medical services. We conducted a rapid HCV testing pilot at probation/parole offices in Rhode Island. Overall, 130 people accepted rapid HCV testing, of whom 12 had reactive tests. Only four of these individuals presented to a community-based clinic for confirmatory testing, despite being offered a monetary incentive. Identifying and addressing barriers to HCV confirmatory testing and follow-up care is critical to increasing the uptake of HCV care and treatment in this vulnerable population.

  17. Rapid declines of large mammal populations after the collapse of the Soviet Union.

    Science.gov (United States)

    Bragina, Eugenia V; Ives, A R; Pidgeon, A M; Kuemmerle, T; Baskin, L M; Gubar, Y P; Piquer-Rodríguez, M; Keuler, N S; Petrosyan, V G; Radeloff, V C

    2015-06-01

    Anecdotal evidence suggests that socioeconomic shocks strongly affect wildlife populations, but quantitative evidence is sparse. The collapse of socialism in Russia in 1991 caused a major socioeconomic shock, including a sharp increase in poverty. We analyzed population trends of 8 large mammals in Russia from 1981 to 2010 (i.e., before and after the collapse). We hypothesized that the collapse would first cause population declines, primarily due to overexploitation, and then population increases due to adaptation of wildlife to new environments following the collapse. The long-term Database of the Russian Federal Agency of Game Mammal Monitoring, consisting of up to 50,000 transects that are monitored annually, provided an exceptional data set for investigating these population trends. Three species showed strong declines in population growth rates in the decade following the collapse, while grey wolf (Canis lupus) increased by more than 150%. After 2000 some trends reversed. For example, roe deer (Capreolus spp.) abundance in 2010 was the highest of any period in our study. Likely reasons for the population declines in the 1990s include poaching and the erosion of wildlife protection enforcement. The rapid increase of the grey wolf populations is likely due to the cessation of governmental population control. In general, the widespread declines in wildlife populations after the collapse of the Soviet Union highlight the magnitude of the effects that socioeconomic shocks can have on wildlife populations and the possible need for special conservation efforts during such times. © 2015 Society for Conservation Biology.

  18. Bone turnover markers: Emerging tool in the management of osteoporosis

    Directory of Open Access Journals (Sweden)

    Sahana Shetty

    2016-01-01

    Full Text Available Bone is a dynamic tissue which undergoes constant remodeling throughout the life span. Bone turnover is balanced with coupling of bone formation and resorption at various rates leading to continuous remodeling of bone. A study of bone turnover markers (BTMs provides an insight of the dynamics of bone turnover in many metabolic bone disorders. An increase in bone turnover seen with aging and pathological states such as osteoporosis leads to deterioration of bone microarchitecture and thus contributes to an increase in the risk of fracture independent of low bone mineral density (BMD. These microarchitectural alterations affecting the bone quality can be assessed by BTMs and thus may serve as a complementary tool to BMD in the assessment of fracture risk. A systematic search of literature regarding BTMs was carried out using the PubMed database for the purpose of this review. Various reliable, rapid, and cost-effective automated assays of BTMs with good sensitivity are available for the management of osteoporosis. However, BTMs are subjected to various preanalytical and analytical variations necessitating strict sample collection and assays methods along with utilizing ethnicity-based reference standards for different populations. Estimation of fracture risk and monitoring the adherence and response to therapy, which is a challenge in a chronic, asymptomatic disease such as osteoporosis, are the most important applications of measuring BTMs. This review describes the physiology of bone remodeling, various conventional and novel BTMs, and BTM assays and their role in the assessment of fracture risk and monitoring response to treatment with antiresorptive or anabolic agents.

  19. Costs of employee turnover

    Directory of Open Access Journals (Sweden)

    Jiří Duda

    2013-01-01

    Full Text Available The aim of this paper is to establish a general methodology for calculating the costs incurred by employee turnover. This paper deals with identification of costs incurred by the departure of an employee, and does not deal with the cost of recruitment of a new employee. Economic calculations are adjusted to the tax policy in the Czech Republic. The costs of employee turnover (according to Bliss, 2012 include the costs of substitution of the unoccupied position, costs of conducting the exit interview and termination of the contract. The cost of an executive’s time to understand the causes of leaving and costs of the leaving employee’s training were also determined. Important factors in the costs of employee turnover also include the loss of knowledge and possibly also a loss of customers. Costs of lost employee and department productiveness represent an important part of the costs of employee turnover, as well. For all of these costs there have been proposed general calculations formulas.

  20. Galaxy Zoo: evidence for rapid, recent quenching within a population of AGN host galaxies

    Science.gov (United States)

    Smethurst, R. J.; Lintott, C. J.; Simmons, B. D.; Schawinski, K.; Bamford, S. P.; Cardamone, C. N.; Kruk, S. J.; Masters, K. L.; Urry, C. M.; Willett, K. W.; Wong, O. I.

    2016-12-01

    We present a population study of the star formation history of 1244 Type 2 active galactic nuclei (AGN) host galaxies, compared to 6107 inactive galaxies. A Bayesian method is used to determine individual galaxy star formation histories, which are then collated to visualize the distribution for quenching and quenched galaxies within each population. We find evidence for some of the Type 2 AGN host galaxies having undergone a rapid drop in their star formation rate within the last 2 Gyr. AGN feedback is therefore important at least for this population of galaxies. This result is not seen for the quenching and quenched inactive galaxies whose star formation histories are dominated by the effects of downsizing at earlier epochs, a secondary effect for the AGN host galaxies. We show that histories of rapid quenching cannot account fully for the quenching of all the star formation in a galaxy's lifetime across the population of quenched AGN host galaxies, and that histories of slower quenching, attributed to secular (non-violent) evolution, are also key in their evolution. This is in agreement with recent results showing that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes. The availability of gas in the reservoirs of a galaxy, and its ability to be replenished, appear to be the key drivers behind this co-evolution.

  1. Six rapid assessments of alcohol and other substance use in populations displaced by conflict

    Directory of Open Access Journals (Sweden)

    Adelekan Moruf

    2011-02-01

    Full Text Available Abstract Background Substance use among populations displaced by conflict is a neglected area of public health. Alcohol, khat, benzodiazepine, opiate, and other substance use have been documented among a range of displaced populations, with wide-reaching health and social impacts. Changing agendas in humanitarian response-including increased prominence of mental health and chronic illness-have so far failed to be translated into meaningful interventions for substance use. Methods Studies were conducted from 2006 to 2008 in six different settings of protracted displacement, three in Africa (Kenya, Liberia, northern Uganda and three in Asia (Iran, Pakistan, and Thailand. We used intervention-oriented qualitative Rapid Assessment and Response methods, adapted from two decades of experience among non-displaced populations. The main sources of data were individual and group interviews conducted with a culturally representative (non-probabilistic sample of community members and service providers. Results Widespread use of alcohol, particularly artisanally-produced alcohol, in Kenya, Liberia, Uganda, and Thailand, and opiates in Iran and Pakistan was believed by participants to be linked to a range of health, social and protection problems, including illness, injury (intentional and unintentional, gender-based violence, risky behaviour for HIV and other sexually transmitted infection and blood-borne virus transmission, as well as detrimental effects to household economy. Displacement experiences, including dispossession, livelihood restriction, hopelessness and uncertain future may make communities particularly vulnerable to substance use and its impact, and changing social norms and networks (including the surrounding population may result in changed - and potentially more harmful-patterns of use. Limited access to services, including health services, and exclusion from relevant host population programmes, may exacerbate the harmful consequences

  2. The population genomics of rapid adaptation: disentangling signatures of selection and demography in white sands lizards.

    Science.gov (United States)

    Laurent, Stefan; Pfeifer, Susanne P; Settles, Matthew L; Hunter, Samuel S; Hardwick, Kayla M; Ormond, Louise; Sousa, Vitor C; Jensen, Jeffrey D; Rosenblum, Erica Bree

    2016-01-01

    Understanding the process of adaptation during rapid environmental change remains one of the central focal points of evolutionary biology. The recently formed White Sands system of southern New Mexico offers an outstanding example of rapid adaptation, with a variety of species having rapidly evolved blanched forms on the dunes that contrast with their close relatives in the surrounding dark soil habitat. In this study, we focus on two of the White Sands lizard species, Sceloporus cowlesi and Aspidoscelis inornata, for which previous research has linked mutations in the melanocortin-1 receptor gene (Mc1r) to blanched coloration. We sampled populations both on and off the dunes and used a custom sequence capture assay based on probed fosmid libraries to obtain >50 kb of sequence around Mc1r and hundreds of other random genomic locations. We then used model-based statistical inference methods to describe the demographic and adaptive history characterizing the colonization of White Sands. We identified a number of similarities between the two focal species, including strong evidence of selection in the blanched populations in the Mc1r region. We also found important differences between the species, suggesting different colonization times, different genetic architecture underlying the blanched phenotype and different ages of the beneficial alleles. Finally, the beneficial allele is dominant in S. cowlesi and recessive in A. inornata, allowing for a rare empirical test of theoretically expected patterns of selective sweeps under these differing models. © 2015 John Wiley & Sons Ltd.

  3. China's rapidly aging population creates policy challenges in shaping a viable long-term care system.

    Science.gov (United States)

    Feng, Zhanlian; Liu, Chang; Guan, Xinping; Mor, Vincent

    2012-12-01

    In China, formal long-term care services for the large aging population have increased to meet escalating demands as demographic shifts and socioeconomic changes have eroded traditional elder care. We analyze China's evolving long-term care landscape and trace major government policies and private-sector initiatives shaping it. Although home and community-based services remain spotty, institutional care is booming with little regulatory oversight. Chinese policy makers face mounting challenges overseeing the rapidly growing residential care sector, given the tension arising from policy inducements to further institutional growth, a weak regulatory framework, and the lack of enforcement capacity. We recommend addressing the following pressing policy issues: building a balanced system of services and avoiding an "institutional bias" that promotes rapid growth of elder care institutions over home or community-based care; strengthening regulatory oversight and quality assurance with information systems; and prioritizing education and training initiatives to grow a professionalized long-term care workforce.

  4. Emerging infectious disease leads to rapid population declines of common British birds.

    Directory of Open Access Journals (Sweden)

    Robert A Robinson

    Full Text Available Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period.

  5. Emerging Infectious Disease Leads to Rapid Population Declines of Common British Birds

    Science.gov (United States)

    Toms, Mike P.; Peck, Kirsi M.; Kirkwood, James K.; Chantrey, Julian; Clatworthy, Innes R.; Evans, Andy D.; Hughes, Laura A.; Hutchinson, Oliver C.; John, Shinto K.; Pennycott, Tom W.; Perkins, Matthew W.; Rowley, Peter S.; Simpson, Vic R.; Tyler, Kevin M.; Cunningham, Andrew A.

    2010-01-01

    Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period. PMID:20805869

  6. Agglomeration and Firm Turnover

    OpenAIRE

    Marjan Nasir

    2013-01-01

    The geographic and industrial concentration of firms affects firm turnover, as highlighted in research on industrial organization. This study conducts a firm-level analysis to determine the impact of agglomeration on firm entry and exit in domestic industries in Punjab, Pakistan. The study also illustrates how some industries exist in clusters while others are highly dispersed. The results suggest that firm entry and exit is higher in highly agglomerated industries.

  7. Seasonal groundwater turnover

    OpenAIRE

    Nordell, Bo; Engström, Maria

    2006-01-01

      Seasonal air temperature variations and corresponding changes in groundwater temperature cause convective movements in groundwater similar to the seasonal turnover in lakes. Numerical simulations were performed to investigate the natural conditions for thermally driven groundwater convection to take place. Thermally driven convection could be triggered by a horizontal groundwater flow, Convection then starts at a considerably lower Rayleigh number (Ra) than the general critical Rayleigh ...

  8. Rapid Decrease in Populations of Wild Ring-Tailed Lemurs (Lemur catta) in Madagascar.

    Science.gov (United States)

    LaFleur, Marni; Clarke, Tara A; Reuter, Kim; Schaeffer, Toby

    2016-01-01

    Lemurs are the most threatened group of mammals on earth. Lemur catta (ring-tailed lemur) represents one of the most iconic lemur species and faces numerous anthropogenic threats in the wild. In this study, we present population estimates from 32 sites across the range of L. catta, collected from primary and secondary data sources, to assess the number of ring-tailed lemurs left in the wild. We estimate that there are approximately 2,220 individual L. catta remaining in the 32 sites considered. We note local extinctions of populations of L. catta in at least 12 of the 32 sites examined, and that significantly more extinctions occurred in areas without some form of protection. This decrease in extant populations could represent a decrease of more than 95% of all ring-tailed lemurs in Madagascar since the year 2000. While these results should be considered preliminary, we stress the rapid decline of the species and note that habitat loss, bushmeat hunting and the illegal pet trade are driving populations to local extinction. Based on the data presented here, urgent and immediate funding and conservation action are crucial to ensure the viability of the remaining wild populations of ring-tailed lemurs. © 2017 S. Karger AG, Basel.

  9. Rapid global expansion of the fungal disease chytridiomycosis into declining and healthy amphibian populations.

    Directory of Open Access Journals (Sweden)

    Timothy Y James

    2009-05-01

    Full Text Available The fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis, is enigmatic because it occurs globally in both declining and apparently healthy (non-declining amphibian populations. This distribution has fueled debate concerning whether, in sites where it has recently been found, the pathogen was introduced or is endemic. In this study, we addressed the molecular population genetics of a global collection of fungal strains from both declining and healthy amphibian populations using DNA sequence variation from 17 nuclear loci and a large fragment from the mitochondrial genome. We found a low rate of DNA polymorphism, with only two sequence alleles detected at each locus, but a high diversity of diploid genotypes. Half of the loci displayed an excess of heterozygous genotypes, consistent with a primarily clonal mode of reproduction. Despite the absence of obvious sex, genotypic diversity was high (44 unique genotypes out of 59 strains. We provide evidence that the observed genotypic variation can be generated by loss of heterozygosity through mitotic recombination. One strain isolated from a bullfrog possessed as much allelic diversity as the entire global sample, suggesting the current epidemic can be traced back to the outbreak of a single clonal lineage. These data are consistent with the current chytridiomycosis epidemic resulting from a novel pathogen undergoing a rapid and recent range expansion. The widespread occurrence of the same lineage in both healthy and declining populations suggests that the outcome of the disease is contingent on environmental factors and host resistance.

  10. Validity and feasibility of a satellite imagery-based method for rapid estimation of displaced populations

    Directory of Open Access Journals (Sweden)

    Checchi Francesco

    2013-01-01

    Full Text Available Abstract Background Estimating the size of forcibly displaced populations is key to documenting their plight and allocating sufficient resources to their assistance, but is often not done, particularly during the acute phase of displacement, due to methodological challenges and inaccessibility. In this study, we explored the potential use of very high resolution satellite imagery to remotely estimate forcibly displaced populations. Methods Our method consisted of multiplying (i manual counts of assumed residential structures on a satellite image and (ii estimates of the mean number of people per structure (structure occupancy obtained from publicly available reports. We computed population estimates for 11 sites in Bangladesh, Chad, Democratic Republic of Congo, Ethiopia, Haiti, Kenya and Mozambique (six refugee camps, three internally displaced persons’ camps and two urban neighbourhoods with a mixture of residents and displaced ranging in population from 1,969 to 90,547, and compared these to “gold standard” reference population figures from census or other robust methods. Results Structure counts by independent analysts were reasonably consistent. Between one and 11 occupancy reports were available per site and most of these reported people per household rather than per structure. The imagery-based method had a precision relative to reference population figures of Conclusions In settings with clearly distinguishable individual structures, the remote, imagery-based method had reasonable accuracy for the purposes of rapid estimation, was simple and quick to implement, and would likely perform better in more current application. However, it may have insurmountable limitations in settings featuring connected buildings or shelters, a complex pattern of roofs and multi-level buildings. Based on these results, we discuss possible ways forward for the method’s development.

  11. Cancer survivors in Switzerland: a rapidly growing population to care for

    Science.gov (United States)

    2013-01-01

    Background Cancer survivors are a heterogeneous group with complex health problems. Data concerning its total number and growing dynamics for Switzerland are scarce and outdated. Methods Population and mortality data were retrieved from the Swiss Federal Statistical Office (FSO). Incidence and relative survival for invasive cancers were computed using data from the cancer registries Geneva (1970–2009), St. Gallen - Appenzell (1980–2010), Grisons & Glarus (1989–2010), and Valais (1989–2010). We estimated prevalence for 1990–2010 using the Prevalence, Incidence Approach MODel (PIAMOD) method. We calculated trends in prevalence estimates by Joinpoint analysis. Projections were extrapolated using the above models and based on time trends of the period 2007–2010. Results The estimated number of cancer survivors increased from 139′717 in 1990 (2.08% of the population) to 289′797 persons in 2010 (3.70%). The growth rate shows an exponential shape and was 3.3% per year in the period 2008 to 2010. Almost half of the survivors have a history of breast, prostate or colorectal cancer. Among cancer survivors, 55% are women but the increases have been more marked in men (p Switzerland. Conclusions There is a rapidly growing population of cancer survivors in Switzerland whose needs and concerns are largely unknown. PMID:23764068

  12. How Employee Turnover Affects Productivity

    DEFF Research Database (Denmark)

    Eriksen, Bo

    Research on employee turnover suggests that turnover results in negative organization-level outcomes. This paper provides a firm-level analysis of the impact of the in- and outflows of human resources on productivity and how the presence of organizational slack resources moderates the effects...... of employee turnover. Drawing on a unique longitudinal dataset of 2,926 Danish manufacturing firms that combine individual-level data with firm-level data, the paper shows that job turnover has a substantial negative effect on total productivity but that the firm’s size, its capital intensity, and its age...

  13. Rapid Population Growth and Human Carrying Capacity: Two Perspectives. World Bank Staff Working Papers No. 690 and Population and Development Series No. 15.

    Science.gov (United States)

    Mahar, Dennis J., Ed.; And Others

    Two perspectives on carrying capacity and population growth are examined. The first perspective, "Carrying Capacity and Rapid Population Growth: Definition, Cases, and Consequences" (Robert Muscat), explores the possible meanings of the idea of carrying capacity under developing country conditions, looks at historical and present-day cases of…

  14. Evidence from phylogenetic and genome fingerprinting analyses suggests rapidly changing variation in Halorubrum and Haloarcula populations

    Science.gov (United States)

    Ram Mohan, Nikhil; Fullmer, Matthew S.; Makkay, Andrea M.; Wheeler, Ryan; Ventosa, Antonio; Naor, Adit; Gogarten, J. Peter; Papke, R. Thane

    2014-01-01

    Halobacteria require high NaCl concentrations for growth and are the dominant inhabitants of hypersaline environments above 15% NaCl. They are well-documented to be highly recombinogenic, both in frequency and in the range of exchange partners. In this study, we examine the genetic and genomic variation of cultured, naturally co-occurring environmental populations of Halobacteria. Sequence data from multiple loci (~2500 bp) identified many closely and more distantly related strains belonging to the genera Halorubrum and Haloarcula. Genome fingerprinting using a random priming PCR amplification method to analyze these isolates revealed diverse banding patterns across each of the genera and surprisingly even for isolates that are identical at the nucleotide level for five protein coding sequenced loci. This variance in genome structure even between identical multilocus sequence analysis (MLSA) haplotypes indicates that accumulation of genomic variation is rapid: faster than the rate of third codon substitutions. PMID:24782838

  15. Evidence from phylogenetic and genome fingerprinting analyses suggests rapidly changing variation in Halorubrum and Haloarcula populations

    Directory of Open Access Journals (Sweden)

    Nikhil eRam Mohan

    2014-04-01

    Full Text Available Halobacteria require high NaCl concentrations for growth and are the dominant inhabitants of hypersaline environments above 15% NaCl. They are well documented to be highly recombinogenic, both in frequency and in the range of exchange partners. In this study, we examine the genetic and genomic variation of cultured, naturally co-occurring environmental populations of Halobacteria. Sequence data from multiple loci (~2500bp identified closely related strains belonging to the genera Halorubrum and Haloarcula. Genome fingerprinting using a random priming PCR amplification method to analyze these isolates revealed diverse banding patterns within and across each of the genera and surprisingly even for isolates that are identical at the nucleotide level for five protein coding sequenced loci. This variance in genome structure even between identical multilocus sequence analysis (MLSA haplotypes suggests that accumulation of variation is rapid, perhaps occurring every generation.

  16. Neptune: a bioinformatics tool for rapid discovery of genomic variation in bacterial populations.

    Science.gov (United States)

    Marinier, Eric; Zaheer, Rahat; Berry, Chrystal; Weedmark, Kelly A; Domaratzki, Michael; Mabon, Philip; Knox, Natalie C; Reimer, Aleisha R; Graham, Morag R; Chui, Linda; Patterson-Fortin, Laura; Zhang, Jian; Pagotto, Franco; Farber, Jeff; Mahony, Jim; Seyer, Karine; Bekal, Sadjia; Tremblay, Cécile; Isaac-Renton, Judy; Prystajecky, Natalie; Chen, Jessica; Slade, Peter; Van Domselaar, Gary

    2017-10-13

    The ready availability of vast amounts of genomic sequence data has created the need to rethink comparative genomics algorithms using 'big data' approaches. Neptune is an efficient system for rapidly locating differentially abundant genomic content in bacterial populations using an exact k-mer matching strategy, while accommodating k-mer mismatches. Neptune's loci discovery process identifies sequences that are sufficiently common to a group of target sequences and sufficiently absent from non-targets using probabilistic models. Neptune uses parallel computing to efficiently identify and extract these loci from draft genome assemblies without requiring multiple sequence alignments or other computationally expensive comparative sequence analyses. Tests on simulated and real datasets showed that Neptune rapidly identifies regions that are both sensitive and specific. We demonstrate that this system can identify trait-specific loci from different bacterial lineages. Neptune is broadly applicable for comparative bacterial analyses, yet will particularly benefit pathogenomic applications, owing to efficient and sensitive discovery of differentially abundant genomic loci. The software is available for download at: http://github.com/phac-nml/neptune. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  17. Rapid assessment of visual impairment in urban population of Delhi, India.

    Science.gov (United States)

    Gupta, Noopur; Vashist, Praveen; Malhotra, Sumit; Senjam, Suraj Singh; Misra, Vasundhara; Bhardwaj, Amit

    2015-01-01

    To determine the prevalence, causes and associated demographic factors related to visual impairment amongst the urban population of New Delhi, India. A population-based, cross-sectional study was conducted in East Delhi district using cluster random sampling methodology. This Rapid Assessment of Visual Impairment (RAVI) survey involved examination of all individuals aged 40 years and above in 24 randomly selected clusters of the district. Visual acuity (VA) assessment and comprehensive ocular examination were done during the door-to-door survey. A questionnaire was used to collect personal and demographic information of the study population. Blindness and Visual Impairment was defined as presenting VA visual impairment. Of 2421 subjects enumerated, 2331 (96.3%) were available for ophthalmic examination. Among those examined, 49.3% were males. The prevalence of visual impairment (VI) in the study population, was 11.4% (95% C.I. 10.1, 12.7) and that of blindness was 1.2% (95% C.I. 0.8, 1.6). Uncorrected refractive error was the leading cause of VI accounting for 53.4% of all VI followed by cataract (33.8%). With multivariable logistic regression, the odds of having VI increased with age (OR = 24.6[95% C.I.: 14.9, 40.7]; p visual impairment is considerable in this region despite availability of adequate eye care facilities. Awareness generation and simple interventions like cataract surgery and provision of spectacles will help to eliminate the major causes of blindness and visual impairment in this region.

  18. Application of Molecular Cytogenetic Technique for Rapid Prenatal Diagnosis of Aneuploidies in Iranian Population

    Directory of Open Access Journals (Sweden)

    Habib Nasiri

    2009-06-01

    Full Text Available Objective: Classic cell culture and karyotyping is routinely used for prenatal detection of different chromosomal abnormalities. Molecular cytogenetic techniques have also recently been developed and used for this purpose. Quantitative florescence PCR using short tandem repeat (STR markers has more potential for high throughput diagnosis. Marker heterozygosity in short tandem repeats (STR is of critical importance in the clinical applicablity of this method. Materials and Methods: Different STR markers on chromosomes 13, 18, 21, X and Y  were analysed from  amniotic samples to detect related disorders such as Down, Edward, Patau,  Klinefelter sundromes , as well as sex chromosomes numerical abnormalities . Results: In our population some markers (D18S976, DXS6854, D21S11, and D21S1411 showed alleles with sizes out of expected ranges. But others occupied narrower range of predicted distribution. Most markers have enough heterozygosity (66.3-94.7 to be used for prenatal diagnosis. Furthermore, results obtained from full karyotype for all samples were in concordance with results of molecular cytogenetic testing. Conclusion: It is concluded that, in urgent situations, if proper markers used, molecular cytogenetic testing (QF-PCR could be a useful method for rapid prenatal diagnosis (PND in populations with high rate of consanguinity such as Iran.  

  19. Rapid expansion of intravitreal drug injection procedures, 2000 to 2008: a population-based analysis.

    Science.gov (United States)

    Campbell, Robert J; Bronskill, Susan E; Bell, Chaim M; Paterson, J Michael; Whitehead, Marlo; Gill, Sudeep S

    2010-03-01

    To evaluate patterns of care for age-related macular degeneration following the introduction of vascular endothelial growth factor inhibitors. Using a population-based retrospective design, we studied monthly fee claims for intravitreal injections submitted to the Ontario Health Insurance Plan between January 1, 2000, and March 30, 2008, and linked procedures to the physicians who performed them. This database records physician services provided as part of universal health care insurance coverage in Ontario, Canada. This program covers all residents of Ontario, which had an average population of 12.1 million during the study period. Following regulatory approval of bevacizumab for colorectal cancer in 2005, off-label use of this drug for the treatment of retinal disease, particularly age-related macular degeneration, became increasingly common. The rate of intravitreal injections in Ontario rapidly grew 8-fold, and this growth preceded the availability of ranibizumab by more than a year. Moreover, in 2007, more than 50% of intravitreal injections in Ontario were performed by 3% of ophthalmologists. The development of vascular endothelial growth factor inhibitors has revolutionized the treatment of age-related macular degeneration. To our knowledge, this study is the first to quantify the dramatic uptake of these treatments at a population level. Our findings also suggest that off-label injection of bevacizumab was highly prevalent in Ontario. Serial intravitreal injections requiring direct physician administration and the concentration of injection procedures in the hands of a small number of ophthalmologists have the potential to affect services for other vision-threatening conditions.

  20. Managing voluntary turnover through challenging assignments

    NARCIS (Netherlands)

    Preenen, P.T.Y.; de Pater, I.E.; van Vianen, A.E.M.; Keijzer, L.

    2011-01-01

    This study examines employees’ challenging assignments as manageable means to reduce turnover intentions, job search behaviors, and voluntary turnover. Results indicate that challenging assignments are negatively related to turnover intentions and job search behaviors and that these relationships

  1. Managing voluntary turnover through challenging assignments

    NARCIS (Netherlands)

    Preenen, P.T.Y.; Pater, I.E. de; Vianen, A.E.M. van; Keijzer, L.

    2011-01-01

    This study examines employees' challenging assignments as manageable means to reduce turnover intentions, job search behaviors, and voluntary turnover. Results indicate that challenging assignments are negatively related to turnover intentions and job search behaviors and that these relationships

  2. Work and Career considerations in Understanding Employee Turnover Intentions and Turnover: Development of the Turnover Diagnostic.

    Science.gov (United States)

    1984-08-01

    researchers have noted that organizations perceived not to link rewards to performance had higher turnover ( Hellriegel & White, 1973; Hulln, 1966, 1968...Telly, French, & Scott, 1971). Similarly, some company policy and administrative Issues related to pay and promotion ( Hellriegel & White, 1973...practices are a strong correlate of turnover (Dansereau, Cashman, & Graen, 1973; Fleishman & Harris, 1962; Graen & Ginsburgh, 1977; Hellriegel & White

  3. Rapid assessment of trachoma in underserved population of Car-Nicobar Island, India.

    Directory of Open Access Journals (Sweden)

    Praveen Vashist

    Full Text Available PURPOSE: To determine the burden of trachoma and its related risk factors amongst the native population of Car-Nicobar Island in India. METHODS: Rapid assessment for trachoma was conducted in ten villages of Car-Nicobar Island according to standard WHO guidelines. An average of 50 children aged 1-9 years were assessed clinically for signs of active trachoma and facial cleanliness in each village. Additionally, all adults above 15 years of age in these households were examined for evidence of trachomatous trichiasis and corneal opacity. Environmental risk factors contributing to trachoma like limited access to potable water & functional latrine, presence of animal pen and garbage within the Nicobari hut were also noted in all villages. RESULTS: Out of a total of fifteen villages in Car-Nicobar Island, ten villages were selected for trachoma survey depending on evidence of socio-developmental indicators like poverty and decreased access to water, sanitation and healthcare facilities. The total population of the selected clusters was 7277 in the ten villages. Overall, 251 of 516 children (48.6%;CI: 46.5-55.1 had evidence of follicular stage of trachoma and 11 children (2.1%;CI:1.0-3.4 had evidence of inflammatory stage of trachoma. Nearly 15%(CI:12.1-18.3 children were noted to have unclean faces in the ten villages. Trachomatous trichiasis was noted in 73 adults (1.0%;CI:0.8-1.2. The environmental sanitation was not found to be satisfactory in the surveyed villages mainly due to the co-habitance of Nicobari people with domestic animals like pigs, hens, goats, dogs, cats etc in most (96.4% of the households. CONCLUSION: Active trachoma and trachomatous trichiasis was observed in all the ten villages surveyed, wherein trachoma control measures are needed.

  4. Can transformational managers control turnover intention?

    National Research Council Canada - National Science Library

    Massad A Alatawi

    2017-01-01

    .... The purpose of this study was to measure the correlation between transformational leadership style and turnover intention to control the employee turnover rate in organisations. Research method...

  5. Rapid assessment of populations trends of invasive species: Singular Spectrum Analysis (SSA

    Directory of Open Access Journals (Sweden)

    DANA, ED

    2010-01-01

    Full Text Available Singular Spectrum Analysis (SSA is a powerful analytical approach for biodi-versity management. Its main advan-tages are due to its intuitive processing and visualization, since mathematical workflow is conceptually similar to the widely accepted Principal Components Analysis. Detailed analyses of popula-tion trends with mathematical tools are often difficult to achieve for managers by a number of reasons (large numbers or areas monitored, large number of species, insufficient statistics skills, strong knowledge level in demographic analyses, etc.. SSA has been used since the 1970’s in signal processing to clarify signal vs. noisy information, but it has also been used in climate change analy-sis and other developmental areas. Be-sides, SSA is a rapid-learning method for technicians and managers with medium level of mathematical knowledge. Free software in Unix environment is avail-able. Unfortunately, no free and friendly software is available for Win-dows SO. Although R package may offer solutions for really advanced users, it does not fit real work situations for managers of biological invasions. Cater-pillar (Gistat Group, Ltd is by now, the best option found by the author in terms of price, facility for results inter-pretation and time consumed in learn-ing. The main disadvantage is the poor content of tutorial files

  6. Investigation of QF-PCR Application for Rapid Prenatal Diagnosis of Chromosomal Aneuploidies in Iranian Population.

    Science.gov (United States)

    Nasiri, Habib; Noori-Dalooi, Mohammad-Reza; Dastan, Jila; Ghaffari, Saeed-Reza

    2011-03-01

    G-Banding followed by standard chromosome analysis is routinely used for prenatal detection of chromosomal abnormalities. In recent years, molecular cytogenetic techniques have been developed for rapid diagnosis of chromosomal abnormalities. Among these methods Quantitative Florescence Polymerase Chain Reaction (QF-PCR) has been widely used for this purpose. Heterozygosity of short tandem repeat (STR) markers which leads to informativity is the most critical requirement for feasibility of QF-PCR. In this study we analyzed several short tandem repeats on chromosomes 13, 18, 21, X and Y on amniotic fluid samples obtained from PND candidates to diagnose conditions such as Down, Edward and Patau syndromes and also numerical sex chromosome abnormalities such as Klinefelter and Turner syndromes. Most of the analyzed STRs had acceptable heterozygosity (66.3-94.7) to be used in QF-PCR based prenatal diagnosis. Moreover, results obtained from both methods (standard karyotype and QF-PCR) for all samples were in accordance with each other. In case of using appropriate STR markers, and in certain clinical indications, QF-PCR could be used as useful technique for prenatal diagnosis even in consanguine populations such as Iranians.

  7. When evolution is the solution to pollution: Key principles, and lessons from rapid repeated adaptation of killifish (Fundulus heteroclitus) populations

    OpenAIRE

    Whitehead, Andrew; Clark, Bryan W.; Reid, Noah M.; Hahn, Mark E.; Nacci, Diane

    2017-01-01

    Abstract For most species, evolutionary adaptation is not expected to be sufficiently rapid to buffer the effects of human‐mediated environmental changes, including environmental pollution. Here we review how key features of populations, the characteristics of environmental pollution, and the genetic architecture underlying adaptive traits, may interact to shape the likelihood of evolutionary rescue from pollution. Large populations of Atlantic killifish (Fundulus heteroclitus) persist in som...

  8. Homogenous Population Genetic Structure of the Non-Native Raccoon Dog (Nyctereutes procyonoides) in Europe as a Result of Rapid Population Expansion.

    Science.gov (United States)

    Drygala, Frank; Korablev, Nikolay; Ansorge, Hermann; Fickel, Joerns; Isomursu, Marja; Elmeros, Morten; Kowalczyk, Rafał; Baltrunaite, Laima; Balciauskas, Linas; Saarma, Urmas; Schulze, Christoph; Borkenhagen, Peter; Frantz, Alain C

    2016-01-01

    The extent of gene flow during the range expansion of non-native species influences the amount of genetic diversity retained in expanding populations. Here, we analyse the population genetic structure of the raccoon dog (Nyctereutes procyonoides) in north-eastern and central Europe. This invasive species is of management concern because it is highly susceptible to fox rabies and an important secondary host of the virus. We hypothesized that the large number of introduced animals and the species' dispersal capabilities led to high population connectivity and maintenance of genetic diversity throughout the invaded range. We genotyped 332 tissue samples from seven European countries using 16 microsatellite loci. Different algorithms identified three genetic clusters corresponding to Finland, Denmark and a large 'central' population that reached from introduction areas in western Russia to northern Germany. Cluster assignments provided evidence of long-distance dispersal. The results of an Approximate Bayesian Computation analysis supported a scenario of equal effective population sizes among different pre-defined populations in the large central cluster. Our results are in line with strong gene flow and secondary admixture between neighbouring demes leading to reduced genetic structuring, probably a result of its fairly rapid population expansion after introduction. The results presented here are remarkable in the sense that we identified a homogenous genetic cluster inhabiting an area stretching over more than 1500km. They are also relevant for disease management, as in the event of a significant rabies outbreak, there is a great risk of a rapid virus spread among raccoon dog populations.

  9. Collagen turnover after tibial fractures

    DEFF Research Database (Denmark)

    Joerring, S; Krogsgaard, M; Wilbek, H

    1994-01-01

    Collagen turnover after tibial fractures was examined in 16 patients with fracture of the tibial diaphysis and in 8 patients with fracture in the tibial condyle area by measuring sequential changes in serological markers of turnover of types I and III collagen for up to 26 weeks after fracture....... The markers were the carboxy-terminal extension peptide of type I procollagen (PICP), the amino-terminal extension peptide of type III procollagen (PIIINP), and the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP). The latter is a new serum marker of degradation of type I...... collagen. A group comparison showed characteristic sequential changes in the turnover of types I and III collagen in fractures of the tibial diaphysis and tibial condyles. The turnover of type III collagen reached a maximum after 2 weeks in both groups. The synthesis of type I collagen reached a maximum...

  10. 'Memory and molecular turnover,' 30 years after inception.

    Science.gov (United States)

    Meagher, Richard B

    2014-01-01

    In 1984 Sir Francis Crick hypothesized that memory is recorded in the brain as reversible modifications to DNA and protein, but acknowledged that most biomolecules turn over too rapidly to account for long-term memories. To accommodate this possible paradox he modeled an enzymatic mechanism to maintain modifications on hemi-modified multimeric symmetrical molecules. While studies on the turnover of chromatin modifications that may be involved in memory are in their infancy, an exploration of his model in the light of modern epigenetics produced somewhat surprising results. The molecular turnover rates for two classes of chromatin modifications believed to record and store durable memories were approximated from experiments using diverse approaches and were found to be remarkably short. The half-lives of DNA cytosine methylation and post-translationally modified nucleosomal histones are measured in hours and minutes, respectively, for a subset of sites on chromatin controlling gene expression. It appears likely that the turnover of DNA methylation in the brain and in neurons, in particular, is even more rapid than in other cell types and organs, perhaps accommodating neuronal plasticity, learning, and memory. The machinery responsible for the rapid turnover of DNA methylation and nucleosomal histone modifications is highly complex, partially redundant, and appears to act in a sequence specific manner. Molecular symmetry plays an important part in maintaining site-specific turnover, but its particular role in memory maintenance is unknown. Elucidating Crick's paradox, the contradiction between rapid molecular turnover of modified biomolecules and long-term memory storage, appears fundamental to understanding cognitive function and neurodegenerative disease.

  11. When evolution is the solution to pollution: Key principles, and lessons from rapid repeated adaptation of killifish (Fundulus heteroclitus) populations

    Science.gov (United States)

    For most species, evolutionary adaptation is not expected to be sufficiently rapid to buffer the effects of human-mediated environmental changes. Yet large persistent populations of small bodied fish residing in some of the most contaminated estuaries of the US have provided some...

  12. [Turnover Experience of Male Nurses].

    Science.gov (United States)

    Kim, Hyunsu; Lee, Jeongseop

    2017-02-01

    The aim of this study was to identify turnover experiences of men in nursing and to derive a substantive theory on the turnover experience of men who are nurses. Data were collected through in-depth interviews with 13 men who had worked as a nurse for 1 year or more, and had a turnover experience during that period. Collected data were analyzed on the basis of Strauss and Corbin's grounded theory. The core category in the turnover experiences of the respondents was 'seeking a stable place for me'. In the analysis of the core category, types of 'contentment', 'seeking', 'survival' and 'confusion' were identified. The sequential stages of these nurses' turnover experience were 'confrontation', 'incertitude', 'retrying' and 'realization'. However, when a problem arose in the process, they returned to the stage of confusion. Thus, these stages could occur in a circular fashion. These findings provide a deep understanding of the turnover experience of men in nursing and offers new information about how they adapt to nursing practice. The findings should be useful as foundational data for men who hope to become nurses and also for managers responsible for nurses who are men.

  13. Quantitative analysis of protein turnover in plants.

    Science.gov (United States)

    Nelson, Clark J; Li, Lei; Millar, A Harvey

    2014-03-01

    Proteins are constantly being synthesised and degraded as plant cells age and as plants grow, develop and adapt the proteome. Given that plants develop through a series of events from germination to fruiting and even undertake whole organ senescence, an understanding of protein turnover as a fundamental part of this process in plants is essential. Both synthesis and degradation processes are spatially separated in a cell across its compartmented structure. The majority of protein synthesis occurs in the cytosol, while synthesis of specific components occurs inside plastids and mitochondria. Degradation of proteins occurs in both the cytosol, through the action of the plant proteasome, and in organelles and lytic structures through different protease classes. Tracking the specific synthesis and degradation rate of individual proteins can be undertaken using stable isotope feeding and the ability of peptide MS to track labelled peptide fractions over time. Mathematical modelling can be used to follow the isotope signature of newly synthesised protein as it accumulates and natural abundance proteins as they are lost through degradation. Different technical and biological constraints govern the potential for the use of (13)C, (15)N, (2)H and (18)O for these experiments in complete labelling and partial labelling strategies. Future development of quantitative protein turnover analysis will involve analysis of protein populations in complexes and subcellular compartments, assessing the effect of PTMs and integrating turnover studies into wider system biology study of plants. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Work-life balance, job satisfaction and turnover intention amongst ...

    African Journals Online (AJOL)

    Talent retention is of particular concern in the information technology (IT) sector owing to globalisation, the skills shortage and rapidly advancing technology. Employee turnover has signifi cant costs and negative consequences for organisations. The objective of this study was to explore the association between employees' ...

  15. Organizational turnover as endogenous precursor of industry dynamics and organizational dissolution

    OpenAIRE

    Cattani, Gino; Johannes M. Pennings; Wezel, Filippo Carlo

    2002-01-01

    This paper studies the effect of organizational turnover on firm survival within the Dutch accounting service industry during the period 1880-1986. We address three issues: (1) estimating the effect of organizational turnover on organizational dissolution; (2) showing the significance of propinquity in isolating that effect; (3) exposing population dynamics through different levels of analysis. The results of our analysis confirm that turnover is an important endogenous force shaping the evol...

  16. Homogenous Population Genetic Structure of the Non-Native Raccoon Dog (Nyctereutes procyonoides in Europe as a Result of Rapid Population Expansion.

    Directory of Open Access Journals (Sweden)

    Frank Drygala

    Full Text Available The extent of gene flow during the range expansion of non-native species influences the amount of genetic diversity retained in expanding populations. Here, we analyse the population genetic structure of the raccoon dog (Nyctereutes procyonoides in north-eastern and central Europe. This invasive species is of management concern because it is highly susceptible to fox rabies and an important secondary host of the virus. We hypothesized that the large number of introduced animals and the species' dispersal capabilities led to high population connectivity and maintenance of genetic diversity throughout the invaded range. We genotyped 332 tissue samples from seven European countries using 16 microsatellite loci. Different algorithms identified three genetic clusters corresponding to Finland, Denmark and a large 'central' population that reached from introduction areas in western Russia to northern Germany. Cluster assignments provided evidence of long-distance dispersal. The results of an Approximate Bayesian Computation analysis supported a scenario of equal effective population sizes among different pre-defined populations in the large central cluster. Our results are in line with strong gene flow and secondary admixture between neighbouring demes leading to reduced genetic structuring, probably a result of its fairly rapid population expansion after introduction. The results presented here are remarkable in the sense that we identified a homogenous genetic cluster inhabiting an area stretching over more than 1500km. They are also relevant for disease management, as in the event of a significant rabies outbreak, there is a great risk of a rapid virus spread among raccoon dog populations.

  17. Protein turnover methods in single-celled organisms: dynamic SILAC.

    Science.gov (United States)

    Claydon, Amy J; Beynon, Robert J

    2011-01-01

    Early achievements in proteomics were qualitative, typified by the identification of very small quantities of proteins. However, as the subject has developed, there has been a pressure to develop approaches to define the amounts of each protein--whether in a relative or an absolute sense. A further dimension to quantitative proteomics embeds the behavior of each protein in terms of its turnover. Virtually every protein in the cell is in a dynamic state, subject to continuous synthesis and degradation, the relative rates of which control the expansion or the contraction of the protein pool, and the absolute values of which dictate the temporal responsiveness of the protein pool. Strategies must therefore be developed to assess the turnover of individual proteins in the proteome. Because a protein can be turning over rapidly even when the protein pool is in steady state, the only acceptable approach to measure turnover is to use metabolic labels that are incorporated or lost from the protein pool as it is replaced. Using metabolic labeling on a proteome-wide scale in turn requires metabolic labels that contain stable isotopes, the incorporation or loss of which can be assessed by mass spectrometry. A typical turnover experiment is complex. The choice of metabolic label is dictated by several factors, including abundance in the proteome, metabolic redistribution of the label in the precursor pool, and the downstream mass spectrometric analytical protocols. Key issues include the need to control and understand the relative isotope abundance of the precursor, the optimization of label flux into and out of the protein pool, and a sampling strategy that ensures the coverage of the greatest range of turnover rates. Finally, the informatics approaches to data analysis will not be as straightforward as in other areas of proteomics. In this chapter, we will discuss the principles and practice of workflow development for turnover analysis, exemplified by the development of

  18. Job turnover and labor turnover : a taxonomy of employment dynamics

    NARCIS (Netherlands)

    Hassink, Wolter H.J.; Hamermesh, Daniel S.

    1994-01-01

    We present an organized set of stylized facts on the relations among flows of workers,changes in employment and changes in the numer of jobs at the firm level. Job turnover isusually measured by comparing stocks of employment in each firm at two points in time andadding up the absolute employment

  19. Rapid Adaptation of a Daphnia magna Population to Metal Stress Is Associated with Heterozygote Excess.

    Science.gov (United States)

    Hochmuth, Jennifer D; De Meester, Luc; Pereira, Cecília M S; Janssen, Colin R; De Schamphelaere, Karel A C

    2015-08-04

    Although natural populations can harbor evolutionary potential to adapt genetically to chemical stress, it is often thought that natural selection leads to a general reduction of genetic diversity and involves costs. Here, a 10 week microevolution experiment was conducted with a genetically diverse and representative sample of one natural Daphnia magna population that was exposed to copper and zinc. Both Cu- and Zn-selected populations developed a significantly higher metal tolerance (i.e., genetic adaptation), indicated by higher reproduction probabilities of clonal lines in Cu and Zn exposures than observed for the original and control populations. The complete recovery of the population densities after 10 weeks of Zn selection (following an initial decrease of 74%) illustrates an example of evolutionary rescue. Microsatellite genotyping revealed a decrease in clonal diversity but no change in allelic richness, and showed an excess in heterozygosity in the Cu- and Zn-selected populations compared to the control and original populations. The excess heterozygosity in metal-selected populations that we observed has important consequences for risk assessment, as it contributes to the maintenance of a higher allelic diversity under multigenerational chemical exposure. This study is, to our knowledge, the first report of an increase in heterozygosity following multigenerational exposure to metal stress, despite a decline in clonal diversity. In a follow-up study with the Zn-selected populations, we observed no effect of Zn selection on the tolerance to heat and cyanobacteria. However, we observed higher tolerance to Cd in the Zn-selected than in the original and control populations if the 20% effective concentration of Cd was considered (cross-tolerance). Our results suggest only limited costs of adaptation but future research is needed to evaluate the adaptive potential of metal-selected populations to novel stressors and to determine to what extent increased

  20. Health insurance, cost expectations, and adverse job turnover.

    Science.gov (United States)

    Ellis, Randall P; Albert Ma, Ching-To

    2011-01-01

    Because less healthy employees value health insurance more than the healthy ones, when health insurance is newly offered job turnover rates for healthier employees decline less than turnover rates for the less healthy. We call this adverse job turnover, and it implies that a firm's expected health costs will increase when health insurance is first offered. Health insurance premiums may fail to adjust sufficiently fast because state regulations restrict annual premium changes, or insurers are reluctant to change premiums rapidly. Even with premiums set at the long run expected costs, some firms may be charged premiums higher than their current expected costs and choose not to offer insurance. High administrative costs at small firms exacerbate this dynamic selection problem. Using 1998-1999 MEDSTAT MarketScan and 1997 Employer Health Insurance Survey data, we find that expected employee health expenditures at firms that offer insurance have lower within-firm and higher between-firm variance than at firms that do not. Turnover rates are systematically higher in industries in which firms are less likely to offer insurance. Simulations of the offer decision capturing between-firm health-cost heterogeneity and expected turnover rates match the observed pattern across firm sizes well. 2010 John Wiley & Sons, Ltd.

  1. Rise and fall of a wolf population: genetic diversity and structure during recovery, rapid expansion and drastic decline.

    Science.gov (United States)

    Jansson, E; Ruokonen, M; Kojola, I; Aspi, J

    2012-11-01

    The grey wolves (Canis lupus) of Finland have had a varied history, with a period of rapid population expansion after the mid-1990s followed by a decline with a current census size of about 140 wolves. Here, we investigate the impact of unstable population size and connectivity on genetic diversity and structure in a long-term genetic study of 298 Finnish wolves born in 1995-2009 and genotyped for 17 microsatellite loci. During the initial recovery and prior to population expansion, genetic diversity was high (1995-1997: LD-N(e)  = 67.2; H(o)  = 0.749; H(e)  = 0.709) despite a small census size and low number of breeders (N(c)  < 100; N(b)  < 10) likely reflecting the status of the Russian source population. Surprisingly, observed heterozygosity decreased significantly during the study period (t = -2.643, P = 0.021) despite population expansion, likely a result of an increase in inbreeding (F(IS)  = 0.108 in 2007-2009) owing to a low degree of connectivity with adjacent Russian wolf population (m = 0.016-0.090; F(ST)  = 0.086, P < 0.001) and population crash after 2006. However, population growth had a temporary positive impact on N(e) and number of family lines. This study shows that even strong population growth alone might not be adequate to retain genetic diversity, especially when accompanied with low amount of subsequent gene flow and population decline. © 2012 Blackwell Publishing Ltd.

  2. Biotic turnover rates during the Pleistocene-Holocene transition

    Science.gov (United States)

    Stivrins, Normunds; Soininen, Janne; Amon, Leeli; Fontana, Sonia L.; Gryguc, Gražyna; Heikkilä, Maija; Heiri, Oliver; Kisielienė, Dalia; Reitalu, Triin; Stančikaitė, Miglė; Veski, Siim; Seppä, Heikki

    2016-11-01

    The Northern Hemisphere is currently warming at the rate which is unprecedented during the Holocene. Quantitative palaeoclimatic records show that the most recent time in the geological history with comparable warming rates was during the Pleistocene-Holocene transition (PHT) about 14,000 to 11,000 years ago. To better understand the biotic response to rapid temperature change, we explore the community turnover rates during the PHT by focusing on the Baltic region in the southeastern sector of the Scandinavian Ice Sheet, where an exceptionally dense network on microfossil and macrofossil data that reflect the biotic community history are available. We further use a composite chironomid-based summer temperature reconstruction compiled specifically for our study region to calculate the rate of temperature change during the PHT. The fastest biotic turnover in the terrestrial and aquatic communities occurred during the Younger Dryas-Holocene shift at 11,700 years ago. This general shift in species composition was accompanied by regional extinctions, including disappearance of mammoth (Mammuthus primigenius) and reindeer (Rangifer tarandus) and many arctic-alpine plant taxa, such as Dryas octopetala, Salix polaris and Saxifraga aizoides, from the region. This rapid biotic turnover rate occurred when the rate of warming was 0.17 °C/decade, thus slightly lower than the current Northern Hemisphere warming of 0.2 °C/decade. We therefore conclude that the Younger Dryas-Holocene shift with its rapid turnover rates and associated regional extinctions represents an important palaeoanalogue to the current high latitude warming and gives insights about the probable future turnover rates and patterns of the terrestrial and aquatic ecosystem change.

  3. Employee Turnover in MFIs: Reasons & Remedies

    OpenAIRE

    Sk. Mahmudul Alam, Mahmud

    2015-01-01

    At present day’s employee turnover is one of the challenging issues in microfinance sector of Bangladesh. Excessive turnover is not only pricey, but it can create a bad reputation in the MFI sector and among the job seekers. Excessive turnover may be harmful to an MFI's productivity if experienced and efficient employees are often departing and the employee encompasses a high percentage of beginners. The impact of turnover has received substantial attention by the senior management and human ...

  4. Rapid population growth. Effects on the social infrastructures of southern Africa.

    Science.gov (United States)

    Smith, J D

    1995-01-01

    Southern Africa's high rate of population growth and widespread poverty have serious implications for the region's social infrastructure. Large increases in the school-age population have undermined efforts to improve the quality of education since all resources are directed toward expansion of availability. To achieve a teacher-pupil ratio of 1:40 at the primary level and 1:35 at the secondary level, an estimated additional 50,000 classrooms would be required. Also jeopardized by high fertility is access to health services, safe water, and sanitation. In Mozambique, for example, where only 30% of the population has access to health services, the under-five years mortality rate is 297/1000 live births and the physician-population ratio is 1:37,970. Substandard housing, homelessness, congestion, deteriorating public services, pollution, and crime dominate urban areas. The single most effective intervention to reduce population growth in Southern Africa is female education. Women without a secondary education bear an average of seven children; if 40% of women attend secondary school, this drops to three children. Thus, governments must make gender equality a central focus of development planning and ensure that women are participants in this process. Property and inheritance laws that serve to increase the economic need for early marriage should be eliminated. Public health programs, including family planning, must be expanded. Finally, women's organizations should be strengthened and urged to foster female empowerment.

  5. High false-positive rate of human immunodeficiency virus rapid serum screening in a predominantly hispanic prenatal population.

    Science.gov (United States)

    Zacharias, Nikolaos M; Athanassaki, Ioanna D; Sangi-Haghpeykar, Haleh; Gardner, Michael O

    2004-12-01

    To identify the characteristics of the gravidas delivering at our birthing center that place them at risk for false-positive human immunodeficiency virus (HIV) enzyme-linked immunosorbent assay (ELISA). The medical records of all rapid HIV-ELISA-positive gravidas that delivered at our hospital between January 2000 and October 2001 were retrieved, and information was gathered regarding maternal demographics. The results of the Western blot tests were also retrieved and correlated to the ELISA results, across varying maternal characteristics. chi(2), Student's t-test and multivariate analysis were performed, as appropriate, using the SAS software; statistical significance was denoted by ppositive rapid HIV-ELISA out of 9,781 deliveries. Of those, 26 were confirmed as HIV infected by Western blot (overall HIV prevalence: 0.27%, ELISA-positive predictive value: 37.7%). The subgroup prevalence of HIV and positive predictive value of ELISA were 1.53 and 75% among Caucasians; 2.43 and 82.6% among African-Americans; and 0.05 and 9.8% among Hispanics, respectively (p or =5 lifetime) sexual partners was elicited in the majority of HIV-infected patients. The positive predictive value of rapid HIV-ELISA during pregnancy varies widely, depending on maternal race/ethnicity and sexual behavior. The routine disclosure of rapid intrapartum HIV serum screening results prior to Western blot confirmation should be avoided in very low-risk populations.

  6. PENGARUH JOB SATISFACTION TERHADAP OCB DAN TURNOVER INTENTION

    Directory of Open Access Journals (Sweden)

    Febru Rida Ningsih

    2015-06-01

    Full Text Available This article aims to provide the impact of job satisfaction to OCB and turnover intention. This study used a quantitative method with a statistical analysis. Simple analysis regression used to test each hypotheses. The object of this research is a branch of national bank. Population in this research are entire employees of a brach of national bank that is e non frontliner employees. Non-probability sampling is used of this reseach. The measurement of job satiafaction and turnover intention variables used likert scale that developed by Rinaldi (2008 and measurement of OCB variable adopted from  Organ (1988.  The result of this research has shown that hypotheses one is rejected and hypotheses two is accepted. Eventually, through this article, an understanding that job satisfaction does not significantly influence to OCB but job satisfaction has significant influence to turnover intention.

  7. The relationship between bone turnover and insulin sensitivity and secretion

    DEFF Research Database (Denmark)

    Frost, Morten; Balkau, Beverley; Hatunic, Mensud

    2018-01-01

    Bone metabolism appears to influence insulin secretion and sensitivity, and insulin promotes bone formation in animals, but similar evidence in humans is limited. The objectives of this study are to explore if bone turnover markers were associated with insulin secretion and sensitivity...... and to determine if bone turnover markers predict changes in insulin secretion and sensitivity. The study population encompassed 576 non-diabetic adult men with normal glucose tolerance (NGT; n=503) or impaired glucose regulation (IGR; n=73). Baseline markers of bone resorption (CTX) and formation (P1NP) were......, baseline bone turnover markers were neither associated with insulin sensitivity (assessed using hyperinsulinaemic euglycaemic clamp and OGTT) nor with insulin secretion capacity (based on IVGTT and OGTT) at baseline or at follow-up. Although inverse associations between fasting glucose and markers of bone...

  8. Population genomics reveal recent speciation and rapid evolutionary adaptation in polar bears

    DEFF Research Database (Denmark)

    Liu, Shiping; Lorenzen, Eline D.; Fumagalli, Matteo

    2014-01-01

    Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyperlipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show...

  9. Tissue-resident adult stem cell populations of rapidly self-renewing organs

    NARCIS (Netherlands)

    Barker, N.; Bartfeld, S.; Clevers, H.

    2010-01-01

    The epithelial lining of the intestine, stomach, and skin is continuously exposed to environmental assault, imposing a requirement for regular self-renewal. Resident adult stem cell populations drive this renewal, and much effort has been invested in revealing their identity. Reliable adult stem

  10. Optical Coherence Tomography in the UK Biobank Study - Rapid Automated Analysis of Retinal Thickness for Large Population-Based Studies.

    Directory of Open Access Journals (Sweden)

    Pearse A Keane

    Full Text Available To describe an approach to the use of optical coherence tomography (OCT imaging in large, population-based studies, including methods for OCT image acquisition, storage, and the remote, rapid, automated analysis of retinal thickness.In UK Biobank, OCT images were acquired between 2009 and 2010 using a commercially available "spectral domain" OCT device (3D OCT-1000, Topcon. Images were obtained using a raster scan protocol, 6 mm x 6 mm in area, and consisting of 128 B-scans. OCT image sets were stored on UK Biobank servers in a central repository, adjacent to high performance computers. Rapid, automated analysis of retinal thickness was performed using custom image segmentation software developed by the Topcon Advanced Biomedical Imaging Laboratory (TABIL. This software employs dual-scale gradient information to allow for automated segmentation of nine intraretinal boundaries in a rapid fashion.67,321 participants (134,642 eyes in UK Biobank underwent OCT imaging of both eyes as part of the ocular module. 134,611 images were successfully processed with 31 images failing segmentation analysis due to corrupted OCT files or withdrawal of subject consent for UKBB study participation. Average time taken to call up an image from the database and complete segmentation analysis was approximately 120 seconds per data set per login, and analysis of the entire dataset was completed in approximately 28 days.We report an approach to the rapid, automated measurement of retinal thickness from nearly 140,000 OCT image sets from the UK Biobank. In the near future, these measurements will be publically available for utilization by researchers around the world, and thus for correlation with the wealth of other data collected in UK Biobank. The automated analysis approaches we describe may be of utility for future large population-based epidemiological studies, clinical trials, and screening programs that employ OCT imaging.

  11. Dynamics of Adipocyte Turnover in Humans

    Energy Technology Data Exchange (ETDEWEB)

    Spalding, K; Arner, E; Westermark, P; Bernard, S; Buchholz, B; Bergmann, O; Blomqvist, L; Hoffstedt, J; Naslund, E; Britton, T; Concha, H; Hassan, M; Ryden, M; Frisen, J; Arner, P

    2007-07-16

    Obesity is increasing in an epidemic fashion in most countries and constitutes a public health problem by enhancing the risk for cardiovascular disease and metabolic disorders such as type 2 diabetes. Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time in recent history. The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells is thought to be most important. We show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese and even under extreme conditions, indicating that the number of adipocytes is set during childhood and adolescence. To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analyzing the integration of {sup 14}C derived from nuclear bomb tests in genomic DNA. Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. Neither adipocyte death nor generation rate is altered in obesity, suggesting a tight regulation of fat cell number that is independent of metabolic profile in adulthood. The high turnover of adipocytes establishes a new therapeutic target for pharmacological intervention in obesity.

  12. Monitoring the welfare of polar bear populations in a rapidly changing Arctic

    Science.gov (United States)

    Atwood, Todd C.; Duncan, Colleen G.; Patyk, Kelly A.; Sonsthagen, Sarah A.

    2017-01-01

    Most programs for monitoring the welfare of wildlife populations support efforts aimed at reaching discrete management objectives, like mitigating conflict with humans. While such programs can be effective, their limited scope may preclude systemic evaluations needed for large-scale conservation initiatives, like the recovery of at-risk species. We discuss select categories of metrics that can be used to monitor how polar bears (Ursus maritimus) are responding to the primary threat to their long-term persistence—loss of sea ice habitat due to the unabated rise in atmospheric greenhouse gas (GHG; e.g., CO2) concentrations—that can also provide information on ecosystem function and health. Monitoring key aspects of polar bear population dynamics, spatial behavior, health and resiliency can provide valuable insight into ecosystem state and function, and could be a powerful tool for achieving Arctic conservation objectives, particularly those that have transnational policy implications.

  13. Integrated care for older populations and its implementation facilitators and barriers: A rapid scoping review.

    Science.gov (United States)

    Threapleton, Diane E; Chung, Roger Y; Wong, Samuel Y S; Wong, Eliza; Chau, Patsy; Woo, Jean; Chung, Vincent C H; Yeoh, Eng-Kiong

    2017-06-01

    Inform health system improvements by summarizing components of integrated care in older populations. Identify key implementation barriers and facilitators. A scoping review was undertaken for evidence from MEDLINE, the Cochrane Library, organizational websites and internet searches. Eligible publications included reviews, reports, individual studies and policy documents published from 2005 to February 2017. Initial eligible documents were reviews or reports concerning integrated care approaches in older/frail populations. Other documents were later sourced to identify and contextualize implementation issues. Study findings and implementation barriers and facilitators were charted and thematically synthesized. Thematic synthesis using 30 publications identified 8 important components for integrated care in elderly and frail populations: (i) care continuity/transitions; (ii) enabling policies/governance; (iii) shared values/goals; (iv) person-centred care; (v) multi-/inter-disciplinary services; (vi) effective communication; (vii) case management; (viii) needs assessments for care and discharge planning. Intervention outcomes and implementation issues (barriers or facilitators) tend to depend heavily on the context and programme objectives. Implementation issues in four main areas were observed: (i) Macro-level contextual factors; (ii) Miso-level system organization (funding, leadership, service structure and culture); (iii) Miso-level intervention organization (characteristics, resources and credibility) and (iv) Micro-level factors (shared values, engagement and communication). Improving integration in care requires many components. However, local barriers and facilitators need to be considered. Changes are expected to occur slowly and are more likely to be successful where elements of integrated care are well incorporated into local settings.

  14. Effects of breeder turnover and harvest on group composition and recruitment in a social carnivore

    Science.gov (United States)

    Ausband, David E.; Mitchell, Michael S.; Waits, Lisette P.

    2017-01-01

    Breeder turnover can influence population growth in social carnivores through changes to group size, composition and recruitment.Studies that possess detailed group composition data that can provide insights about the effects of breeder turnover on groups have generally been conducted on species that are not subject to recurrent annual human harvest. We wanted to know how breeder turnover affects group composition and how harvest, in turn, affects breeder turnover in cooperatively breeding grey wolves (Canis lupus Linnaeus 1758).We used noninvasive genetic sampling at wolf rendezvous sites to construct pedigrees and estimate recruitment in groups of wolves before and after harvest in Idaho, USA.Turnover of breeding females increased polygamy and potential recruits per group by providing breeding opportunities for subordinates although resultant group size was unaffected 1 year after the turnover. Breeder turnover had no effect on the number of nonbreeding helpers per group. After breeding male turnover, fewer female pups were recruited in the new males’ litters. Harvest had no effect on the frequency of breeder turnover.We found that breeder turnover led to shifts in the reproductive hierarchies within groups and the resulting changes to group composition were quite variable and depended on the sex of the breeder lost. We hypothesize that nonbreeding females direct help away from non-kin female pups to preserve future breeding opportunities for themselves. Breeder turnover had marked effects on the breeding opportunities of subordinates and the number and sex ratios of subsequent litters of pups. Seemingly subtle changes to groups, such as the loss of one individual, can greatly affect group composition, genetic content, and short-term population growth when the individual lost is a breeder.

  15. Effects of breeder turnover and harvest on group composition and recruitment in a social carnivore.

    Science.gov (United States)

    Ausband, David E; Mitchell, Michael S; Waits, Lisette P

    2017-09-01

    Breeder turnover can influence population growth in social carnivores through changes to group size, composition and recruitment. Studies that possess detailed group composition data that can provide insights about the effects of breeder turnover on groups have generally been conducted on species that are not subject to recurrent annual human harvest. We wanted to know how breeder turnover affects group composition and how harvest, in turn, affects breeder turnover in cooperatively breeding grey wolves (Canis lupus Linnaeus 1758). We used noninvasive genetic sampling at wolf rendezvous sites to construct pedigrees and estimate recruitment in groups of wolves before and after harvest in Idaho, USA. Turnover of breeding females increased polygamy and potential recruits per group by providing breeding opportunities for subordinates although resultant group size was unaffected 1 year after the turnover. Breeder turnover had no effect on the number of nonbreeding helpers per group. After breeding male turnover, fewer female pups were recruited in the new males' litters. Harvest had no effect on the frequency of breeder turnover. We found that breeder turnover led to shifts in the reproductive hierarchies within groups and the resulting changes to group composition were quite variable and depended on the sex of the breeder lost. We hypothesize that nonbreeding females direct help away from non-kin female pups to preserve future breeding opportunities for themselves. Breeder turnover had marked effects on the breeding opportunities of subordinates and the number and sex ratios of subsequent litters of pups. Seemingly subtle changes to groups, such as the loss of one individual, can greatly affect group composition, genetic content, and short-term population growth when the individual lost is a breeder. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

  16. Population Genomics Reveal Recent Speciation and Rapid Evolutionary Adaptation in Polar Bears

    OpenAIRE

    Liu, Shiping; Lorenzen, Eline D.; Fumagalli, Matteo; Li, Bo; Harris, Kelley; Xiong, Zijun; ZHOU, Long; Korneliussen, Thorfinn Sand; Somel, Mehmet; Babbitt, Courtney; Wray, Greg; Li, Jianwen; He, Weiming; Wang, Zhuo; Fu, Wenjing

    2014-01-01

    Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyperlipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479–343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under...

  17. The relationships between psychological strain, organizational support, affective commitment and turnover intentions of highly educated hospitality employees

    NARCIS (Netherlands)

    Tromp, D.M.; Rheede, van A.; Blomme, R.J.

    2010-01-01

    Turnover of highly educated employees in the hospitality industry is growing rapidly. A predictor of turnover in the hospitality industry recently put forward, but not yet fully researched, is psychological strain. This chapter investigates the role of psychological strain and organizational support

  18. FREQ-Seq: a rapid, cost-effective, sequencing-based method to determine allele frequencies directly from mixed populations.

    Directory of Open Access Journals (Sweden)

    Lon M Chubiz

    Full Text Available Understanding evolutionary dynamics within microbial populations requires the ability to accurately follow allele frequencies through time. Here we present a rapid, cost-effective method (FREQ-Seq that leverages Illumina next-generation sequencing for localized, quantitative allele frequency detection. Analogous to RNA-Seq, FREQ-Seq relies upon counts from the >10(5 reads generated per locus per time-point to determine allele frequencies. Loci of interest are directly amplified from a mixed population via two rounds of PCR using inexpensive, user-designed oligonucleotides and a bar-coded bridging primer system that can be regenerated in-house. The resulting bar-coded PCR products contain the adapters needed for Illumina sequencing, eliminating further library preparation. We demonstrate the utility of FREQ-Seq by determining the order and dynamics of beneficial alleles that arose as a microbial population, founded with an engineered strain of Methylobacterium, evolved to grow on methanol. Quantifying allele frequencies with minimal bias down to 1% abundance allowed effective analysis of SNPs, small in-dels and insertions of transposable elements. Our data reveal large-scale clonal interference during the early stages of adaptation and illustrate the utility of FREQ-Seq as a cost-effective tool for tracking allele frequencies in populations.

  19. High resolution melting analytical platform for rapid prenatal and postnatal diagnosis of β-thalassemia common among Southeast Asian population.

    Science.gov (United States)

    Prajantasen, Thanet; Fucharoen, Supan; Fucharoen, Goonnapa

    2015-02-20

    High resolution melting (HRM) analysis is a powerful technology for scanning sequence alteration. We have applied this HRM assay to screen common β-thalassemia mutations found among Southeast Asian population. Known DNA samples with 8 common mutations were used in initial development of the methods including -28 A-G, codon 17 A-T, IVSI-1G-T, IVSI-5G-C, codon 26G-A (Hb E), codons 41/42 -TTCT, codons 71/72+A and IVSII-654 C-T. Further validation was done on 60 postnatal and 6 prenatal diagnoses of β-thalassemia. Each mutation has specific HRM profile which could be used in rapid screening. Apart from those with DNA deletions, the results of HRM assay matched 100% with those of routine diagnosis made by routine allele specific PCR. In addition, the HRM assay could initially recognize three unknown mutations including a hitherto un-described one in Thai population. The established HRM assay should prove useful for rapid and high throughput platform for screening and prenatal diagnosis of β-thalassemia common in the region. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Rapidly increasing body mass index among children, adolescents and young adults in a transitioning population, South Africa, 2008-15.

    Science.gov (United States)

    Sartorius, B; Sartorius, K; Taylor, M; Aagaard-Hansen, J; Dukhi, N; Day, C; Ndlovu, N; Slotow, R; Hofman, K

    2017-12-14

    There is a global epidemic of overweight and obesity; however, this rate of increase is even greater in some low- and middle-income countries (LMIC). South Africa (SA) is undergoing rapid socioeconomic and demographic changes that have triggered a rapid nutrition transition. The paper focuses on the recent rate of change of body mass index (BMI) among children, adolescents and young adults, further stratified by key sociodemographic factors. We analysed mean BMI of 28 247 individuals (including children) from 7301 households by age and year, from anthropometric data from four national cross-sectional (repeated panel) surveys using non-linear fitted curves and associated 95% confidence intervals. From 2008 to 2015, there was rapid rise in mean BMI in the 6-25 age band, with the highest risk (3-4+ BMI unit increase) among children aged 8-10 years. The increase was largely among females in urban areas and of middle-high socioeconomic standing. Prominent gains were also observed in certain rural areas, with extensive geographical heterogeneity across the country. We have demonstrated a major deviation from the current understanding of patterns of BMI increase, with a rate of increase substantially greater in the developing world context compared with the global pattern. This population-wide effect will have major consequences for national development as the epidemic of related non-communicable disease unfolds, and will overtax the national health care budget. Our refined understanding highlights that risks are further compounded for certain groups/places, and emphasizes that urgent geographical and population-targeted interventions are necessary. These interventions could include a sugar tax, clearer food labelling, revised school feeding programmes and mandatory bans on unhealthy food marketing to children.The scenario unfolding in South Africa will likely be followed in other LMICs.

  1. POPULATION GENOMICS REVEAL RECENT SPECIATION AND RAPID EVOLUTIONARY ADAPTATION IN POLAR BEARS

    Science.gov (United States)

    Liu, Shiping; Lorenzen, Eline D.; Fumagalli, Matteo; Li, Bo; Harris, Kelley; Xiong, Zijun; Zhou, Long; Korneliussen, Thorfinn Sand; Somel, Mehmet; Babbitt, Courtney; Wray, Greg; Li, Jianwen; He, Weiming; Wang, Zhuo; Fu, Wenjing; Xiang, Xueyan; Morgan, Claire C.; Doherty, Aoife; O’Connell, Mary J.; McInerney, James O.; Born, Erik W.; Dalén, Love; Dietz, Rune; Orlando, Ludovic; Sonne, Christian; Zhang, Guojie; Nielsen, Rasmus; Willerslev, Eske; Wang, Jun

    2014-01-01

    SUMMARY Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyperlipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479–343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under strong positive selection are associated with cardiomyopathy and vascular disease, implying important reorganization of the cardio-vascular system. One of the genes showing the strongest evidence of selection, APOB, encodes the primary lipoprotein component of low-density lipoprotein (LDL); functional mutations in APOB may explain how polar bears are able to cope with life-long elevated LDL levels that are associated with high risk of heart disease in humans. PMID:24813606

  2. Hybrid mathematical model of cardiomyocyte turnover in the adult human heart.

    Directory of Open Access Journals (Sweden)

    Jeremy A Elser

    Full Text Available The capacity for cardiomyocyte regeneration in the healthy adult human heart is fundamentally relevant for both myocardial homeostasis and cardiomyopathy therapeutics. However, estimates of cardiomyocyte turnover rates conflict greatly, with a study employing C14 pulse-chase methodology concluding 1% annual turnover in youth declining to 0.5% with aging and another using cell population dynamics indicating substantial, age-increasing turnover (4% increasing to 20%.Create a hybrid mathematical model to critically examine rates of cardiomyocyte turnover derived from alternative methodologies.Examined in isolation, the cell population analysis exhibited severe sensitivity to a stem cell expansion exponent (20% variation causing 2-fold turnover change and apoptosis rate. Similarly, the pulse-chase model was acutely sensitive to assumptions of instantaneous incorporation of atmospheric C14 into the body (4-fold impact on turnover in young subjects while numerical restrictions precluded otherwise viable solutions. Incorporating considerations of primary variable sensitivity and controversial model assumptions, an unbiased numerical solver identified a scenario of significant, age-increasing turnover (4-6% increasing to 15-22% with age that was compatible with data from both studies, provided that successive generations of cardiomyocytes experienced higher attrition rates than predecessors.Assignment of histologically-observed stem/progenitor cells into discrete regenerative phenotypes in the cell population model strongly influenced turnover dynamics without being directly testable. Alternatively, C14 trafficking assumptions and restrictive models in the pulse-chase model artificially eliminated high-turnover solutions. Nevertheless, discrepancies among recent cell turnover estimates can be explained and reconciled. The hybrid mathematical model provided herein permits further examination of these and forthcoming datasets.

  3. The Relationship between Managerial Satisfaction and Job Turnover Intention: The Mediating Role of Job Satisfaction

    Directory of Open Access Journals (Sweden)

    Rüveyda Öztürk Basol

    2017-09-01

    Full Text Available The growth of service sector in Turkey occurs faster than the other sectors and the number of shopping malls increases correspondingly. The rapid growth of the number of shopping malls has necessitated the measurement of the attitudes of the employees in this sector. This study demonstrated that the gender, marital status and age were not the significant variables on job satisfaction, managerial satisfaction and job turnover intention; however, education status and income status were found to be significant variables on job satisfaction and job turnover intention. In addition, job satisfaction fully mediated the relationship between managerial satisfaction and job turnover intention.

  4. Rapid growth and genetic diversity retention in an isolated reintroduced black bear population in the central appalachians

    Science.gov (United States)

    Murphy, Sean M.; Cox, John J.; Clark, Joseph D.; Augustine, Benjamin J.; Hast, John T.; Gibbs, Dan; Strunk, Michael; Dobey, Steven

    2015-01-01

    Animal reintroductions are important tools of wildlife management to restore species to their historical range, and they can also create unique opportunities to study population dynamics and genetics from founder events. We used non-invasive hair sampling in a systematic, closed-population capture-mark-recapture (CMR) study design at the Big South Fork (BSF) area in Kentucky during 2010 and Tennessee during 2012 to estimate the demographic and genetic characteristics of the black bear (Ursus americanus) population that resulted from a reintroduced founding population of 18 bears in 1998. We estimated 38 (95% CI: 31–66) and 190 (95% CI: 170–219) bears on the Kentucky and Tennessee study areas, respectively. Based on the Tennessee abundance estimate alone, the mean annual growth rate was 18.3% (95% CI: 17.4–19.5%) from 1998 to 2012. We also compared the genetic characteristics of bears sampled during 2010–2012 to bears in the population during 2000–2002, 2–4 years following reintroduction, and to the source population. We found that the level of genetic diversity since reintroduction as indicated by expected heterozygosity (HE) remained relatively constant (HE(source, 2004) = 0.763, HE(BSF, 2000–2002) = 0.729, HE(BSF, 2010–2012) = 0.712) and the effective number of breeders (NB) remained low but had increased since reintroduction in the absence of sufficient immigration (NB(BSF, 2000–2002) = 12, NB(BSF, 2010–2012)  = 35). This bear population appears to be genetically isolated, but contrary to our expectations, we did not find evidence of genetic diversity loss or other deleterious genetic effects typically observed from small founder groups. We attribute that to high initial genetic diversity in the founder group combined with overlapping generations and rapid population growth. Although the population remains relatively small, the reintroduction using a small founder group appears to be demographically and genetically

  5. Population genomics reveal recent speciation and rapid evolutionary adaptation in polar bears.

    Science.gov (United States)

    Liu, Shiping; Lorenzen, Eline D; Fumagalli, Matteo; Li, Bo; Harris, Kelley; Xiong, Zijun; Zhou, Long; Korneliussen, Thorfinn Sand; Somel, Mehmet; Babbitt, Courtney; Wray, Greg; Li, Jianwen; He, Weiming; Wang, Zhuo; Fu, Wenjing; Xiang, Xueyan; Morgan, Claire C; Doherty, Aoife; O'Connell, Mary J; McInerney, James O; Born, Erik W; Dalén, Love; Dietz, Rune; Orlando, Ludovic; Sonne, Christian; Zhang, Guojie; Nielsen, Rasmus; Willerslev, Eske; Wang, Jun

    2014-05-08

    Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyper-lipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479-343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under strong positive selection are associated with cardiomyopathy and vascular disease, implying important reorganization of the cardiovascular system. One of the genes showing the strongest evidence of selection, APOB, encodes the primary lipoprotein component of low-density lipoprotein (LDL); functional mutations in APOB may explain how polar bears are able to cope with life-long elevated LDL levels that are associated with high risk of heart disease in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Rapid identification of causal mutations in tomato EMS populations via mapping-by-sequencing.

    Science.gov (United States)

    Garcia, Virginie; Bres, Cécile; Just, Daniel; Fernandez, Lucie; Tai, Fabienne Wong Jun; Mauxion, Jean-Philippe; Le Paslier, Marie-Christine; Bérard, Aurélie; Brunel, Dominique; Aoki, Koh; Alseekh, Saleh; Fernie, Alisdair R; Fraser, Paul D; Rothan, Christophe

    2016-12-01

    The tomato is the model species of choice for fleshy fruit development and for the Solanaceae family. Ethyl methanesulfonate (EMS) mutants of tomato have already proven their utility for analysis of gene function in plants, leading to improved breeding stocks and superior tomato varieties. However, until recently, the identification of causal mutations that underlie particular phenotypes has been a very lengthy task that many laboratories could not afford because of spatial and technical limitations. Here, we describe a simple protocol for identifying causal mutations in tomato using a mapping-by-sequencing strategy. Plants displaying phenotypes of interest are first isolated by screening an EMS mutant collection generated in the miniature cultivar Micro-Tom. A recombinant F2 population is then produced by crossing the mutant with a wild-type (WT; non-mutagenized) genotype, and F2 segregants displaying the same phenotype are subsequently pooled. Finally, whole-genome sequencing and analysis of allele distributions in the pools allow for the identification of the causal mutation. The whole process, from the isolation of the tomato mutant to the identification of the causal mutation, takes 6-12 months. This strategy overcomes many previous limitations, is simple to use and can be applied in most laboratories with limited facilities for plant culture and genotyping.

  7. Rapid and sensitive magnetoelastic biosensors for the detection of Salmonella typhimurium in a mixed microbial population.

    Science.gov (United States)

    Guntupalli, R; Lakshmanan, R S; Hu, J; Huang, T S; Barbaree, J M; Vodyanoy, V; Chin, B A

    2007-07-01

    In this article, we report the results of an investigation into the performance of a wireless, magnetoelastic biosensor designed to selectively detect Salmonella typhimurium in a mixed microbial population. The Langmuir-Blodgett (LB) monolayer technique was employed for antibody (specific to Salmonella sp.) immobilization on rectangular shaped strip magnetoelastic sensors (2 x 0.4 x 0.015 mm). Bacterial binding to the antibody on the sensor surface changes the resonance parameters, and these changes were quantified as a shift in the sensor's resonance frequency. Response of the sensors to increasing concentrations (5 x 10(1) to 5 x 10(8) cfu/ml) of S. typhimurium in a mixture of extraneous foodborne pathogens (Escherichia coli O157:H7 and Listeria monocytogenes) was studied. A detection limit of 5 x 10(3) cfu/ml and a sensitivity of 139 Hz/decade were observed for the 2 x 0.4 x 0.015 mm sensors. Binding kinetics studies have shown that the dissociation constant (K(d)) and the binding valencies for water samples spiked with S. typhimurium was 435 cfu/ml and 2.33 respectively. The presence of extraneous microorganisms in the mixture did not produce an appreciable change in the biosensor's dose response behavior.

  8. Rapid and unambiguous detection of DNase I hypersensitive site in rare population of cells.

    Directory of Open Access Journals (Sweden)

    Wei-Ping Zeng

    Full Text Available DNase I hypersensitive (DHS sites are important for understanding cis regulation of gene expression. However, existing methods for detecting DHS sites in small numbers of cells can lead to ambiguous results. Here we describe a simple new method, in which DNA fragments with ends generated by DNase I digestion are isolated and used as templates for two PCR reactions. In the first PCR, primers are derived from sequences up- and down-stream of the DHS site. If the DHS site exists in the cells, the first PCR will not produce PCR products due to the cuts of the templates by DNase I between the primer sequences. In the second PCR, one primer is derived from sequence outside the DHS site and the other from the adaptor. This will produce a smear of PCR products of different sizes due to cuts by DNase I at different positions at the DHS site. With this design, we detected a DHS site at the CD4 gene in two CD4 T cell populations using as few as 2×10(4 cells. We further validated this method by detecting a DHS site of the IL-4 gene that is specifically present in type 2 but not type 1 T helper cells. Overall, this method overcomes the interference by genomic DNA not cut by DNase I at the DHS site, thereby offering unambiguous detection of DHS sites in the cells.

  9. Dynamic large-scale chromosomal rearrangements fuel rapid adaptation in yeast populations.

    Directory of Open Access Journals (Sweden)

    Shang-Lin Chang

    Full Text Available Large-scale genome rearrangements have been observed in cells adapting to various selective conditions during laboratory evolution experiments. However, it remains unclear whether these types of mutations can be stably maintained in populations and how they impact the evolutionary trajectories. Here we show that chromosomal rearrangements contribute to extremely high copper tolerance in a set of natural yeast strains isolated from Evolution Canyon (EC, Israel. The chromosomal rearrangements in EC strains result in segmental duplications in chromosomes 7 and 8, which increase the copy number of genes involved in copper regulation, including the crucial transcriptional activator CUP2 and the metallothionein CUP1. The copy number of CUP2 is correlated with the level of copper tolerance, indicating that increasing dosages of a single transcriptional activator by chromosomal rearrangements has a profound effect on a regulatory pathway. By gene expression analysis and functional assays, we identified three previously unknown downstream targets of CUP2: PHO84, SCM4, and CIN2, all of which contributed to copper tolerance in EC strains. Finally, we conducted an evolution experiment to examine how cells maintained these changes in a fluctuating environment. Interestingly, the rearranged chromosomes were reverted back to the wild-type configuration at a high frequency and the recovered chromosome became fixed in less selective conditions. Our results suggest that transposon-mediated chromosomal rearrangements can be highly dynamic and can serve as a reversible mechanism during early stages of adaptive evolution.

  10. Genetic analysis of morphological traits in a new, versatile, rapid-cycling Brassica rapa recombinant inbred line population

    Science.gov (United States)

    Bagheri, Hedayat; El-Soda, Mohamed; van Oorschot, Inge; Hanhart, Corrie; Bonnema, Guusje; Jansen-van den Bosch, Tanja; Mank, Rolf; Keurentjes, Joost J. B.; Meng, Lin; Wu, Jian; Koornneef, Maarten; Aarts, Mark G. M.

    2012-01-01

    A recombinant inbred line (RIL) population was produced based on a wide cross between the rapid-cycling and self-compatible genotypes L58, a Caixin vegetable type, and R-o-18, a yellow sarson oil type. A linkage map based on 160 F7 lines was constructed using 100 Single nucleotide polymorphisms (SNPs), 130 AFLP®, 27 InDel, and 13 publicly available SSR markers. The map covers a total length of 1150 centiMorgan (cM) with an average resolution of 4.3 cM/marker. To demonstrate the versatility of this new population, 17 traits, related to plant architecture and seed characteristics, were subjected to quantitative trait loci (QTL) analysis. A total of 47 QTLs were detected, each explaining between 6 and 54% of the total phenotypic variance for the concerned trait. The genetic analysis shows that this population is a useful new tool for analyzing genetic variation for interesting traits in B. rapa, and for further exploitation of the recent availability of the B. rapa whole genome sequence for gene cloning and gene function analysis. PMID:22912644

  11. Genetic analysis of morphological traits in a new, versatile, rapid-cycling Brassica rapa recombinant inbred line population

    Directory of Open Access Journals (Sweden)

    Hedayat eBagheri

    2012-08-01

    Full Text Available A recombinant inbred line (RIL population was produced based on a wide cross between the rapid-cycling and self-compatible genotypes L58, a Caixin vegetable type, and R-o-18, a yellow sarson oil type. A linkage map based on 160 F7 lines was constructed using 100 SNP, 130 AFLP®, 27 InDel and 13 publicly available SSR markers. The map covers a total length of 1150 cM with an average resolution of 4.3 cM/marker. To demonstrate the versatility of this new population, 17 traits, related to plant architecture and seed characteristics, were subjected to QTL analysis. A total of 47 QTLs were detected, each explaining between 6 to 54% of the total phenotypic variance for the concerned trait. The genetic analysis shows that this population is a useful new tool for analyzing genetic variation for interesting traits in B. rapa, and for further exploitation of the recent availability of the B. rapa whole genome sequence for gene cloning and gene function analysis.

  12. Influence of rapid rural-urban population migration on riverine nitrogen pollution: perspective from ammonia-nitrogen.

    Science.gov (United States)

    Zhang, Wangshou; Swaney, Dennis P; Hong, Bongghi; Howarth, Robert W; Li, Xuyong

    2017-09-30

    China is undergoing a rapid transition from a rural to an urban society. This societal change is a consequence of a national drive toward economic prosperity. However, accelerated urban development resulting from rapid population migration from rural to urban lands has led to high levels of untreated sewage entering aquatic ecosystems directly. Consequently, many of these regions have been identified as hot spots of riverine nitrogen (N) pollution because of the increasing level of urban point-source discharge. In order to address this concern, we assessed effects of urban development on ammonia-nitrogen (AN) loads using a panel data regression model. The model, expressed as an exponential function of anthropogenic N inputs multiplied by a power function of streamflow, was applied to 20 subwatersheds of the Huai River Basin for the years 2003-2010. The results indicated that this model can account for 81% of the variation in annual AN fluxes over space and time. Application of this model to three scenarios of urban development and sewage treatment (termed urbanization priority, sustainable development, and environmental priority) suggests that future N pollution will inevitably deteriorate if current urban environmental management and investment are not significantly improved. Stronger support for environmental management is very critical to alleviate N pollution and improve water quality. More effort should focus on improving sewage treatment and the N removal rate of the current sewage system in light of the increasing degree of urbanization.

  13. Microbial carbon turnover in the plant-rhizosphere-soil continuum

    Science.gov (United States)

    Malik, Ashish; Dannert, Helena; Griffiths, Robert; Thomson, Bruce; Gleixner, Gerd

    2014-05-01

    Soil microbial biomass contributes significantly to maintenance of soil organic matter (SOM). It is well known that biochemical fractions of soil microorganisms have varying turnover and therefore contribute differentially to soil C storage. Here we compare the turnover rates of different microbial biochemical fractions using a pulse chase 13CO2 plant labelling experiment. The isotope signal was temporally traced into rhizosphere soil microorganisms using the following biomarkers: DNA, RNA, fatty acids and chloroform fumigation extraction derived microbial biomass size classes. C flow into soil microbial functional groups was assessed through phospholipid and neutral lipid fatty acid (PLFA/NLFA) analyses. Highest 13C enrichment was seen in the low molecular weight (LMW) size class of microbial biomass (Δδ13C =151) and in nucleic acids (DNA: 38o RNA: 66) immediately after the pulse followed by a sharp drop. The amount of 13C in the high molecular weight (HMW) microbial biomass (17-81) and total fatty acids (32-54) was lower initially and stayed relatively steady over the 4 weeks experimental period. We found significant differences in turnover rates of different microbial biochemical and size fractions. We infer that LMW cytosolic soluble compounds are rapidly metabolized and linked to respiratory C fluxes, whereas mid-sized products of microbial degradation and HMW polymeric compounds have lower renewal rate in that order. The turnover of cell wall fatty acids was also very slow. DNA and RNA showed faster turnover rate; and as expected RNA renewal was the fastest due to its rapid production by active microorganisms independent of cell replication. 13C incorporation into different functional groups confirmed that mutualistic arbuscular mycorrhizal fungi rely on root C and are important in the initial plant C flux. We substantiated through measurements of isotope incorporation into bacterial RNA that rhizosphere bacteria are also important in the initial C conduit

  14. Population Divergence in Venom Bioactivities of Elapid Snake Pseudonaja textilis: Role of Procoagulant Proteins in Rapid Rodent Prey Incapacitation

    Science.gov (United States)

    Skejić, Jure; Hodgson, Wayne C.

    2013-01-01

    This study looked at how toxic proteins in venoms of adult Australian eastern Brown snakes Pseudonaja textilis from South Australian and Queensland populations interact with physiological functions of the lab SD rat Rattus norvegicus. Circulatory collapse and incoagulable blood occurred instantly after injection of venom under the dorsal skin of anaesthetised and mechanically ventilated rats in an imitation of a P. textilis bite. Intravenous injection of purified P. textilis (Mackay, QLD) venom prothrombin activator proteins caused instant failure of circulation, testifying of high toxicity of these proteins and suggesting their role in rapid incapacitation of rodent prey. The hypothesis is further supported by circulatory collapse occurring instantly despite artificial respiration in envenomed rats and the finding of extremely high venom procoagulant potency in rat plasma. LC-MS and physiology assays revealed divergent venom composition and biological activity of South Australian (Barossa locality) and Queensland (Mackay locality) populations, which may be driven by selection for different prey. The Queensland venom of P. textilis was found to be more procoagulant and to exhibit predominately presynaptic neurotoxicity, while the South Australian venom contained diverse postsynaptic type II and III α-neurotoxins in addition to the presynaptic neurotoxins and caused significantly faster onset of neuromuscular blockade in the rat phrenic nerve-diaphragm preparation. LC-MS analysis found evidence of multiple coagulation factor X-like proteins in P. textilis venoms, including a match to P. textilis coagulation factor X isoform 2, previously known to be expressed only in the liver. PMID:23691135

  15. Rapidly rising incidence of childhood type 1 diabetes in Chinese population: epidemiology in Shanghai during 1997-2011.

    Science.gov (United States)

    Zhao, Zhuhui; Sun, Chengjun; Wang, Chunfang; Li, Pin; Wang, Wei; Ye, Jun; Gu, Xuefan; Wang, Xiaodong; Shen, Shuixian; Zhi, Dijing; Lu, Zhong; Ye, Rong; Cheng, Ruoqian; Xi, Li; Li, Xiaojing; Zheng, Zhangqian; Zhang, Miaoying; Luo, Feihong

    2014-12-01

    The aim of this study was to investigate incidence trend of childhood type 1 diabetes in Shanghai, a megalopolis in east China. We established a population-based retrospective registry for the disease in the city's registered population during 1997-2011 and collected 622 incident type 1 diabetes in children aged 0-14 years. Standardized incidence rates and 95 % CI were estimated by applying the capture-recapture method and assuming Poisson distribution. Incidence trend was analyzed using the Poisson regression model. The mean annual incidence of childhood type 1 diabetes was 3.1 per 100,000 person-years. We did not observe significant difference in incidence between boys and girls. The incidence is unstable and had a mean annual increase 14.2 % per year during the studied period. A faster annual increase was observed in boys, warmer seasons, and in the outer regions of the city. If present trends continue, the number of new type 1 diabetes cases will double from 2016 to 2020, and prevalent cases will sextuple by 2025. Our results showed the incidence of childhood type 1 diabetes was rising rapidly in Shanghai. More studies are needed to analyze incidence changes in other regions of China for appropriate allocation of healthcare resources.

  16. Population divergence in venom bioactivities of elapid snake Pseudonaja textilis: role of procoagulant proteins in rapid rodent prey incapacitation.

    Directory of Open Access Journals (Sweden)

    Jure Skejić

    Full Text Available This study looked at how toxic proteins in venoms of adult Australian eastern Brown snakes Pseudonaja textilis from South Australian and Queensland populations interact with physiological functions of the lab SD rat Rattus norvegicus. Circulatory collapse and incoagulable blood occurred instantly after injection of venom under the dorsal skin of anaesthetised and mechanically ventilated rats in an imitation of a P. textilis bite. Intravenous injection of purified P. textilis (Mackay, QLD venom prothrombin activator proteins caused instant failure of circulation, testifying of high toxicity of these proteins and suggesting their role in rapid incapacitation of rodent prey. The hypothesis is further supported by circulatory collapse occurring instantly despite artificial respiration in envenomed rats and the finding of extremely high venom procoagulant potency in rat plasma. LC-MS and physiology assays revealed divergent venom composition and biological activity of South Australian (Barossa locality and Queensland (Mackay locality populations, which may be driven by selection for different prey. The Queensland venom of P. textilis was found to be more procoagulant and to exhibit predominately presynaptic neurotoxicity, while the South Australian venom contained diverse postsynaptic type II and III α-neurotoxins in addition to the presynaptic neurotoxins and caused significantly faster onset of neuromuscular blockade in the rat phrenic nerve-diaphragm preparation. LC-MS analysis found evidence of multiple coagulation factor X-like proteins in P. textilis venoms, including a match to P. textilis coagulation factor X isoform 2, previously known to be expressed only in the liver.

  17. Rapid changes in transcription profiles of the Plasmodium yoelii yir multigene family in clonal populations: lack of epigenetic memory?

    Directory of Open Access Journals (Sweden)

    Deirdre Cunningham

    Full Text Available The pir multigene family, found in the genomes of Plasmodium vivax, P. knowlesi and the rodent malaria species, encode variant antigens that could be targets of the immune response. Individual parasites of the rodent malaria Plasmodium yoelii, selected by micromanipulation, transcribe only 1 to 3 different pir (yir suggesting tight transcriptional control at the level of individual cells. Using microarray and quantitative RT-PCR, we show that despite this very restricted transcription in a single cell, many yir genes are transcribed throughout the intra-erythrocytic asexual cycle. The timing and level of transcription differs between genes, with some being more highly transcribed in ring and trophozoite stages, whereas others are more highly transcribed in schizonts. Infection of immunodeficient mice with single infected erythrocytes results in populations of parasites each with transcriptional profiles different from that of the parent parasite population and from each other. This drift away from the original 'set' of transcribed genes does not appear to follow a preset pattern and "epigenetic memory" of the yir transcribed in the parent parasite can be rapidly lost. Thus, regulation of pir gene transcription may be different from that of the well-characterised multigene family, var, of Plasmodium falciparum.

  18. Rapid changes in transcription profiles of the Plasmodium yoelii yir multigene family in clonal populations: lack of epigenetic memory?

    Science.gov (United States)

    Cunningham, Deirdre; Fonager, Jannik; Jarra, William; Carret, Celine; Preiser, Peter; Langhorne, Jean

    2009-01-01

    The pir multigene family, found in the genomes of Plasmodium vivax, P. knowlesi and the rodent malaria species, encode variant antigens that could be targets of the immune response. Individual parasites of the rodent malaria Plasmodium yoelii, selected by micromanipulation, transcribe only 1 to 3 different pir (yir) suggesting tight transcriptional control at the level of individual cells. Using microarray and quantitative RT-PCR, we show that despite this very restricted transcription in a single cell, many yir genes are transcribed throughout the intra-erythrocytic asexual cycle. The timing and level of transcription differs between genes, with some being more highly transcribed in ring and trophozoite stages, whereas others are more highly transcribed in schizonts. Infection of immunodeficient mice with single infected erythrocytes results in populations of parasites each with transcriptional profiles different from that of the parent parasite population and from each other. This drift away from the original 'set' of transcribed genes does not appear to follow a preset pattern and "epigenetic memory" of the yir transcribed in the parent parasite can be rapidly lost. Thus, regulation of pir gene transcription may be different from that of the well-characterised multigene family, var, of Plasmodium falciparum.

  19. Rapid evolution in the wild: changes in body size, life-history traits, and behavior in hunted populations of the Japanese mamushi snake.

    Science.gov (United States)

    Sasaki, Kiyoshi; Fox, Stanley F; Duvall, David

    2009-02-01

    Rapid evolution caused by human exploitation of wildlife is not usually addressed in studies of the impacts of such exploitation despite its direct relevance to population persistence. Japanese mamushi (Gloydius blomhoffii), an endemic venomous snake of the Japanese archipelago, has been heavily hunted by humans, and many populations appear to be declining or are already extirpated. We compared local populations that have been hunted regularly with populations that have not been hunted. Mamushi in hunted populations were smaller, had fewer vertebrae, produced more and smaller offspring, had increased reproductive effort among smaller females, and in nature fled at greater distances from an approaching human and were less defensive than mamushi in unhunted populations, as predicted from life-history theory. Heritability estimates for body size, number of vertebrae, and antipredator behavior were statistically significant, and neonates from hunted sites showed the same distribution of altered characters (compared with those from unhunted sites) as adults. Thus, distribution of the divergent trait between hunted and unhunted sites appeared in part to be genetically based, which suggests rapid evolution to human predation pressures. Trait distributions in hunted populations probably deviate from naturally (as opposed to anthropogenically) selected optima and, therefore, may have long-term negative repercussions on population persistence. Because rapid evolution affects a suite of parameters that characterize exploited populations, accurate understanding of the impacts of exploitation and effective resource management and conservation can only be achieved if evolutionary consequences are considered explicitly.

  20. Predicted Relative Metabolomic Turnover (PRMT): determining metabolic turnover from a coastal marine metagenomic dataset.

    Science.gov (United States)

    Larsen, Peter E; Collart, Frank R; Field, Dawn; Meyer, Folker; Keegan, Kevin P; Henry, Christopher S; McGrath, John; Quinn, John; Gilbert, Jack A

    2011-06-14

    The world's oceans are home to a diverse array of microbial life whose metabolic activity helps to drive the earth's biogeochemical cycles. Metagenomic analysis has revolutionized our access to these communities, providing a system-scale perspective of microbial community interactions. However, while metagenome sequencing can provide useful estimates of the relative change in abundance of specific genes and taxa between environments or over time, this does not investigate the relative changes in the production or consumption of different metabolites. We propose a methodology, Predicted Relative Metabolic Turnover (PRMT) that defines and enables exploration of metabolite-space inferred from the metagenome. Our analysis of metagenomic data from a time-series study in the Western English Channel demonstrated considerable correlations between predicted relative metabolic turnover and seasonal changes in abundance of measured environmental parameters as well as with observed seasonal changes in bacterial population structure. The PRMT method was successfully applied to metagenomic data to explore the Western English Channel microbial metabalome to generate specific, biologically testable hypotheses. Generated hypotheses linked organic phosphate utilization to Gammaproteobactaria, Plantcomycetes, and Betaproteobacteria, chitin degradation to Actinomycetes, and potential small molecule biosynthesis pathways for Lentisphaerae, Chlamydiae, and Crenarchaeota. The PRMT method can be applied as a general tool for the analysis of additional metagenomic or transcriptomic datasets.

  1. Relationship between Job Satisfaction and Turnover Intention ...

    African Journals Online (AJOL)

    This study explores the association between job satisfaction and turnover intentions among lecturers in three public universities in Tanzania. It had three objectives: (1) to determine the level of perceived job satisfaction among lecturers; (2) to determine the association between job satisfaction and turnover intention; and (3) ...

  2. Can transformational managers control turnover intention?

    Directory of Open Access Journals (Sweden)

    Massad A. Alatawi

    2017-01-01

    Full Text Available Orientation and research purpose: Employee turnover is a complex phenomenon that has negative consequences for organisations. The purpose of this study was to measure the correlation between transformational leadership style and turnover intention to control the employee turnover rate in organisations.Research method: This study utilised a two-stage clustering method and web-based survey research with a correlational design to collect the data. A total of 356 responses were collected from 14 clusters in Southern California; however, the final selected data for analysis came from 210 subjects with a cluster-sampling design of (14 × 15.Main findings and managerial implications: This study concluded that the transformational leadership style has a negative correlation with turnover intention. Managers who adopt this style of leadership can expect lower rates of turnover; thus, they can stay competitive in an unstable economy and achieve enhanced productivity, improved performance and reduction in expenses.

  3. Rapid approach to the quantitative determination of nocturnal ground irradiance in populated territories: a clear-sky case

    Science.gov (United States)

    Kocifaj, Miroslav; Petržala, Jaromír

    2016-11-01

    A zero-order approach to the solving of the radiative transfer equation and a method for obtaining the horizontal diffuse irradiance at night-time are both developed and intended for wide use in numerical predictions of nocturnal ground irradiance in populated territories. Downward diffuse radiative fluxes are computed with a two-stream approximation, and the data products obtained are useful for scientists who require rapid estimations of illumination levels during the night. The rapid technique presented here is especially important when the entire set of calculations is to be repeated for different lighting technologies and/or radiant intensity distributions with the aim of identifying high-level illuminance/irradiance, the spectral composition of scattered light or other optical properties of diffuse light at the ground level. The model allows for the computation of diffuse horizontal irradiance due to light emissions from ground-based sources with arbitrary spectral compositions. The optical response of a night sky is investigated using the ratio of downward to upward irradiance, R⊥, λ(0). We show that R⊥, λ(0) generally peaks at short wavelengths, thus suggesting that, e.g., the blue light of an LED lamp would make the sky even more bluish. However, this effect can be largely suppressed or even removed with the spectral sensitivity function of the average human eye superimposed on to the lamp spectrum. Basically, blue light scattering dominates at short optical distances, while red light is transmitted for longer distances and illuminates distant places. Computations are performed for unshielded as well as fully shielded lights, while the spectral function R⊥, λ(0) is tabulated to make possible the modelling of various artificial lights, including those not presented here.

  4. Chronic Teacher Turnover in Urban Elementary Schools

    Directory of Open Access Journals (Sweden)

    Kacey Guin

    2004-08-01

    Full Text Available This study examines the characteristics of elementary schools that experience chronic teacher turnover and the impacts of turnover on a school’s working climate and ability to effectively function. Based on evidence from staff climate surveys and case studies, it is clear that high turnover schools face significant organizational challenges. Schools with high teacher turnover rates have difficulty planning and implementing a coherent curriculum and sustaining positive working relationships among teachers. The reality of these organizational challenges is particularly alarming, given that high turnover schools are more likely to serve low-income and minority students. The negative relationship between teacher turnover and school functioning, and the fact that turbulent schools are disproportionately likely to serve lowincome and minority students have important implications for both district and school-level policies. Specifically: Teacher turnover rates are one indicator of school health, which school districts should consider when focusing on school improvements. Districts need to begin by developing the means to identify individual schools that experience high levels of teacher turnover. Current district policies in implementing professional development for teachers in low-performing schools are inefficient when teachers do not remain in the schools in which they are trained. In order for low-performing schools to improve, districts need to consider providing incentive programs so that high quality teachers apply for, and remain in, these schools. Future research is needed to address the causal link between turnover, organizational functioning and student outcomes. Additionally, there is a need for research examining district policies that may facilitate teacher turnover within a district, including how districts place and transfer teachers, as well as how teachers’ salaries are budgeted.

  5. BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, AND POPULATION GRADIENTS IN LOW-MASS GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    El-Badry, Kareem; Geha, Marla [Department of Astronomy, Yale University, New Haven, CT (United States); Wetzel, Andrew; Hopkins, Philip F. [TAPIR, California Institute of Technology, Pasadena, CA USA (United States); Kereš, Dusan; Chan, T. K. [Department of Physics, Center for Astrophysics and Space Sciences, University of California at San Diego, La Jolla (United States); Faucher-Giguère, Claude-André, E-mail: kareem.el-badry@yale.edu [Department of Physics and Astronomy and CIERA, Northwestern University, Evanston, IL (United States)

    2016-04-01

    We examine the effects of stellar feedback and bursty star formation on low-mass galaxies (M{sub star} = 2 × 10{sup 6} − 5 × 10{sup 10} M{sub ⊙}) using the Feedback in Realistic Environments (FIRE) simulations. While previous studies emphasized the impact of feedback on dark matter profiles, we investigate the impact on the stellar component: kinematics, radial migration, size evolution, and population gradients. Feedback-driven outflows/inflows drive significant radial stellar migration over both short and long timescales via two processes: (1) outflowing/infalling gas can remain star-forming, producing young stars that migrate ∼1 kpc within their first 100 Myr, and (2) gas outflows/inflows drive strong fluctuations in the global potential, transferring energy to all stars. These processes produce several dramatic effects. First, galaxies’ effective radii can fluctuate by factors of >2 over ∼200 Myr, and these rapid size fluctuations can account for much of the observed scatter in the radius at fixed M{sub star}. Second, the cumulative effects of many outflow/infall episodes steadily heat stellar orbits, causing old stars to migrate outward most strongly. This age-dependent radial migration mixes—and even inverts—intrinsic age and metallicity gradients. Thus, the galactic-archaeology approach of calculating radial star formation histories from stellar populations at z = 0 can be severely biased. These effects are strongest at M{sub star} ≈ 10{sup 7–9.6} M{sub ⊙}, the same regime where feedback most efficiently cores galaxies. Thus, detailed measurements of stellar kinematics in low-mass galaxies can strongly constrain feedback models and test baryonic solutions to small-scale problems in ΛCDM.

  6. The island-mainland species turnover relationship.

    Science.gov (United States)

    Stuart, Yoel E; Losos, Jonathan B; Algar, Adam C

    2012-10-07

    Many oceanic islands are notable for their high endemism, suggesting that islands may promote unique assembly processes. However, mainland assemblages sometimes harbour comparable levels of endemism, suggesting that island biotas may not be as unique as is often assumed. Here, we test the uniqueness of island biotic assembly by comparing the rate of species turnover among islands and the mainland, after accounting for distance decay and environmental gradients. We modelled species turnover as a function of geographical and environmental distance for mainland (M-M) communities of Anolis lizards and Terrarana frogs, two clades that have diversified extensively on Caribbean islands and the mainland Neotropics. We compared mainland-island (M-I) and island-island (I-I) species turnover with predictions of the M-M model. If island assembly is not unique, then the M-M model should successfully predict M-I and I-I turnover, given geographical and environmental distance. We found that M-I turnover and, to a lesser extent, I-I turnover were significantly higher than predicted for both clades. Thus, in the first quantitative comparison of mainland-island species turnover, we confirm the long-held but untested assumption that island assemblages accumulate biodiversity differently than their mainland counterparts.

  7. Empirical Prediction of Turnovers in NFL Football

    Directory of Open Access Journals (Sweden)

    Joel R. Bock

    2016-12-01

    Full Text Available Turnovers in the National Football League (NFL occur whenever a team loses possession of the ball due to a fumble, or an interception. Turnovers disrupt momentum of the offensive team, and represent lost opportunities to advance downfield and score. Teams with a positive differential turnover margin in a given game win 70 % of the time. Turnovers are statistically rare events, occurring apparently randomly. These characteristics make them difficult to predict. This investigation advances the hypothesis that turnovers are predictable in NFL football. Machine learning models are developed to learn the concept: At any point within a football game, what is the likelihood that a turnover will be observed on the next play from scrimmage? NFL play-by-play data for 32 teams spanning seven full seasons were used to train the models. Results presented suggest evidence to support the working hypothesis. Under certain conditions, both fumbles and interceptions can be anticipated at low false discovery rates (less than 15 % . When a turnover is predicted on the impending play from scrimmage, a high degree of confidence is associated with that prediction. The ability to anticipate catastrophic in-game events may lead to their management and control, ultimately improving the performance of individual athletes and their teams. This investigation contributes to the sports science literature by demonstrating the predictability of in-game events often considered to be essentially random in their occurrence. To the author’s knowledge, direct prediction of turnovers has not previously appeared in the literature, which has focused on retrospective statistical analyses of turnover margin in football games.

  8. The validation of the turnover intention scale

    Directory of Open Access Journals (Sweden)

    Chris F.C. Bothma

    2013-01-01

    Full Text Available Orientation: Turnover intention as a construct has attracted increased research attention in the recent past, but there are seemingly not many valid and reliable scales around to measure turnover intention.Research purpose: This study focused on the validation of a shortened, six-item version of the turnover intention scale (TIS-6.Motivation for the study: The research question of whether the TIS-6 is a reliable and a valid scale for measuring turnover intention and for predicting actual turnover was addressed in this study.Research design, approach and method: The study was based on a census-based sample (n= 2429 of employees in an information, communication and technology (ICT sector company (N= 23 134 where the TIS-6 was used as one of the criterion variables. The leavers (those who left the company in this sample were compared with the stayers (those who remained in the employ of the company in this sample in respect of different variables used in the study.Main findings: It was established that the TIS-6 could measure turnover intentions reliably (α= 0.80. The TIS-6 could significantly distinguish between leavers and stayers (actual turnover, thereby confirming its criterion-predictive validity. The scale also established statistically significant differences between leavers and stayers in respect of a number of the remaining theoretical variables used in the study, thereby also confirming its differential validity. These comparisons were conducted for both the 4-month and the 4-year period after the survey was conducted.Practical/managerial implications: Turnover intention is related to a number of variables in the study which necessitates a reappraisal and a reconceptualisation of existing turnover intention models.Contribution/value-add: The TIS-6 can be used as a reliable and valid scale to assess turnover intentions and can therefore be used in research to validly and reliably assess turnover intentions or to

  9. AN ECONOMETRIC APPROACH ABOUT VOLUNTARY TURNOVER

    Directory of Open Access Journals (Sweden)

    ADALET EREN

    2013-06-01

    Full Text Available This study analyzes individual and organizational variables that affect voluntary turnover are determined in the special defence and security companies. A binomial logistic regression model is used to estimate voluntary turnover.  Binomial Logistic regression, reliability test (scale alfa, variance (ANOVA, Post-hoc/Tukey, correlation (Pearson and other basic statistical techniques  with SPSS 13 statistical packet program was used in the analyzes ofresearch data. The study finds that; situation of suppose working, number of child, number of death child, number of home’s moving, support of rent, total monthly income of household, last work’s region, number of prizes, affect voluntary turnover are determined.

  10. Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar.

    Science.gov (United States)

    Kolby, Jonathan E; Smith, Kristine M; Ramirez, Sara D; Rabemananjara, Falitiana; Pessier, Allan P; Brunner, Jesse L; Goldberg, Caren S; Berger, Lee; Skerratt, Lee F

    2015-01-01

    We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar's reptile species might also be threatened by disease

  11. Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar

    Science.gov (United States)

    Kolby, Jonathan E.; Smith, Kristine M.; Ramirez, Sara D.; Rabemananjara, Falitiana; Pessier, Allan P.; Brunner, Jesse L.; Goldberg, Caren S.; Berger, Lee; Skerratt, Lee F.

    2015-01-01

    We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar's reptile species might also be threatened by disease

  12. THE EFFECT OF JOB SATISFACTION ON IT EMPLOYEES TURNOVER INTENTION IN ISRAEL

    Directory of Open Access Journals (Sweden)

    Ladelsky Limor

    2014-07-01

    Full Text Available Employee voluntary turnover is very costly for companies, particularly for the Hi-Tech sector, where the costs of their IT labor force is expensive. Employees\\' voluntary turnover has substantial negative impacts on the companies especially costs, potential loss of valuable knowledge, skills and organizational knowledge.That is why it becomes a critical issue to take address. Studies have been carried out on the reasons which lead to this tendency, however the ability to explain and predict it remains restricted.The objective of this paper is to present the reasons for voluntary turnover of employees in the IT sector in Israel from the IT employees` perspective. A broad analysis of the field literature led to the following groups of causes affecting voluntary turnover: organizational causes: Human Resource Management (HRM related, organizational culture, job related, leadership and internal marketing related; extra organizational causes: individual and, respectively, labor market related causes. This could be approached as n light of this review this article will focus on one of the extra organizational causes of voluntary turnover, i.e. the effect of job satisfaction on voluntary turnover intention among IT employees in Hi-Tech companies in Israel. This correlation was researched in an extensive empirical study among two population groups: IT employees and IT managers and by using mixed method research (combination of quantitative and qualitative research.The findings that supported the literature show job satisfaction has a negative effect on voluntary turnover intention among IT employees in Hi-Tech companies in Israel. Additionally, it was found that job satisfaction indirectly affects voluntary turnover intentions and that emotional variables such as commitment, motivation and loyalty mediate voluntary turnover intention.This finding is supported partially in the literature which only pointed out commitment as a mediating factor in the

  13. Transitions or turnovers? Climatically-forced extinctions of Homo sapiens and Neanderthals in the east Mediterranean Levant

    Science.gov (United States)

    Shea, John J.

    2008-11-01

    The East Mediterranean Levant is a focal point for debate about evolutionary continuity among Late Pleistocene hominin populations. Changes in the Levantine Middle and Upper Palaeolithic archaeological records are almost invariably described in terms of adaptive shifts and behavioural transitions, rather than as changes in hominin populations. This paper examines evidence for hominin evolutionary continuity in the Levant between 130 and 25 ka. Two inflection points, one within the Middle Palaeolithic ca 75 ka and the other between the Middle and Upper Palaeolithic ca 45 ka, are examined in light of recently-discovered evidence for rapid climate change and environmental deterioration. It is proposed that both periods mark regional extinctions and turnovers of hominin populations. The first of these occurred among early Homo sapiens, the second among Neanderthals. Each event was followed by dispersal of hominin populations into the Levant from adjacent regions. Differences in Middle vs. Upper Palaeolithic Homo sapiens' long-term success in the Levant may reflect recently-evolved strategies for coping with rapid climate change and with colder arid habitats.

  14. Predictors of turnover intentions of highly educated employees in the hospitality industry

    NARCIS (Netherlands)

    Blomme, R.J.; Tromp, D.M.; Rheede, van A.

    2008-01-01

    As management-level turnover is increasing rapidly, one of the major challenges for the hospitality industry is to retain highly educated and highly skilled employees. As the psychological contract approach to the employment relationship had not been investigated with regard to the hospitality

  15. Kinetics of corneal epithelium turnover in vivo. Studies of lovastatin

    Energy Technology Data Exchange (ETDEWEB)

    Cenedella, R.J.; Fleschner, C.R. (Kirksville College of Osteopathic Medicine, MO (USA))

    1990-10-01

    The authors developed a direct chemical approach for estimating the rate of turnover of the corneal epithelium in vivo. The method was used to examine the effects of lovastatin, a potent inhibitor of cholesterol biosynthesis, on proliferation and turnover of the epithelium. Corneal DNA was labeled by pulse injection (IP) of the rat with 3H-thymidine, and 3H-labeled DNA was recovered from peripheral and central corneas over the next 15 days. Only the epithelium became labeled, and the loss of label by cell desquamation began 3 days after injection. The loss of 3H-DNA from the cornea (peripheral plus central region) followed first-order kinetics. The half-life of the disappearance was about 3 days. The peripheral cornea became more highly labeled than the central cornea and began to lose 3H-DNA before the central cornea. These observations support the possibility of a higher mitotic rate in the peripheral region and the centripetal movement of a population of peripheral epithelial cells in the normal cornea. The half-lives of the disappearance of 3H-DNA from peripheral and central corneas measured between days 5 and 15 postinjection were identical, both at 3 days. Complete turnover of the corneal epithelium would, therefore, require about 2 weeks (4-5 half-lives). Treatment of the rat with lovastatin had no obvious effects upon the proliferation or turnover of the corneal epithelium. Although lovastatin inhibited corneal 3-hydroxy-3-methylglutaryl coenzyme A reductase, the key regulatory enzyme of cholesterol synthesis, the cornea compensated by induction of this enzyme so that there was no net inhibition of cholesterol synthesis in the cornea.

  16. Pattern and process in Amazon tree turnover, 1976-2001.

    Science.gov (United States)

    Phillips, O L; Baker, T R; Arroyo, L; Higuchi, N; Killeen, T J; Laurance, W F; Lewis, S L; Lloyd, J; Malhi, Y; Monteagudo, A; Neill, D A; Vargas, P Núñez; Silva, J N M; Terborgh, J; Martínez, R Vásquez; Alexiades, M; Almeida, S; Brown, S; Chave, J; Comiskey, J A; Czimczik, C I; Di Fiore, A; Erwin, T; Kuebler, C; Laurance, S G; Nascimento, H E M; Olivier, J; Palacios, W; Patiño, S; Pitman, N C A; Quesada, C A; Saldias, M; Lezama, A Torres; Vinceti, B

    2004-01-01

    Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that

  17. An "escape clock" for estimating the turnover of SIV DNA in resting CD4⁺ T cells.

    Directory of Open Access Journals (Sweden)

    Jeanette Reece

    Full Text Available Persistence of HIV DNA presents a major barrier to the complete control of HIV infection under current therapies. Most studies suggest that cells with latently integrated HIV decay very slowly under therapy. However, it is much more difficult to study the turnover and persistence of HIV DNA during active infection. We have developed an "escape clock" approach for measuring the turnover of HIV DNA in resting CD4+ T cells. This approach studies the replacement of wild-type (WT SIV DNA present in early infection by CTL escape mutant (EM strains during later infection. Using a strain-specific real time PCR assay, we quantified the relative amounts of WT and EM strains in plasma SIV RNA and cellular SIV DNA. Thus we can track the formation and turnover of SIV DNA in sorted resting CD4+ T cells. We studied serial plasma and PBMC samples from 20 SIV-infected Mane-A*10 positive pigtail macaques that have a signature Gag CTL escape mutation. In animals with low viral load, WT virus laid down early in infection is extremely stable, and the decay of this WT species is very slow, consistent with findings in subjects on anti-retroviral medications. However, during active, high level infection, most SIV DNA in resting cells was turning over rapidly, suggesting a large pool of short-lived DNA produced by recent infection events. Our results suggest that, in order to reduce the formation of a stable population of SIV DNA, it will be important either to intervene very early or intervene during active replication.

  18. Addressing employee turnover and retention: keeping your valued performers.

    Science.gov (United States)

    McConnell, Charles R

    2011-01-01

    Employee turnover and employee retention are inextricably linked; to control turnover is to enhance retention. Turnover is a relatively simple concept; however, considerable confusion often results when addressing turnover because of differences in how it is defined; that is, what is counted, how it is counted, and how the turnover rates are expressed. Turnover is also costly, although not enough attention is paid to its cost because so much of it is indirect and thus not readily visible. There are a variety of causes of turnover, some that can be corrected and some that cannot be avoided. Reducing or otherwise controlling turnover requires continuing management attention to its causes and constant recognition of what can and should be controlled and what cannot be controlled. Ongoing attention to turnover is an essential part of the department manager's role; every improvement in turnover is a direct improvement in retention, with eventual positive effects on the bottom line.

  19. Rapid Buildup of Genetic Diversity in Founder Populations of the Gynodioecious Plant Species Origanum vulgare after Semi-Natural Grassland Restoration

    Science.gov (United States)

    Helsen, Kenny; Jacquemyn, Hans; Hermy, Martin; Vandepitte, Katrien; Honnay, Olivier

    2013-01-01

    In most landscapes the success of habitat restoration is largely dependent on spontaneous colonization of plant species. This colonization process, and the outcome of restoration practices, can only be considered successful if the genetic makeup of founding populations is not eroded through founder effects and subsequent genetic drift. Here we used 10 microsatellite markers to investigate the genetic effects of recent colonization of the long-lived gynodioecious species Origanum vulgare in restored semi-natural grassland patches. We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns. We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them. Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects. Overall population genetic differentiation was low (FST = 0.040). Individuals of restored populations were assigned to on average 6.1 different source populations (likely following the ‘migrant pool’ model). Gene flow was, however, affected by the spatial configuration of the grasslands, with gene flow into the recent populations mainly originating from nearby source populations. This study demonstrates how spontaneous colonization after habitat restoration can lead to viable populations in a relatively short time, overcoming pronounced founder effects, when several source populations are nearby. Restored populations can therefore rapidly act as stepping stones and sources of genetic diversity, likely increasing overall metapopulation viability of the study species. PMID:23840642

  20. Associations between serum leptin level and bone turnover in kidney transplant recipients.

    Science.gov (United States)

    Kovesdy, Csaba P; Molnar, Miklos Z; Czira, Maria E; Rudas, Anna; Ujszaszi, Akos; Rosivall, Laszlo; Szathmari, Miklos; Covic, Adrian; Keszei, Andras; Beko, Gabriella; Lakatos, Peter; Kosa, Janos; Mucsi, Istvan

    2010-12-01

    Obesity is associated with increased parathyroid hormone (PTH) in the general population and in patients with chronic kidney disease (CKD). A direct effect of adipose tissue on bone turnover through leptin production has been suggested, but such an association has not been explored in kidney transplant recipients. This study examined associations of serum leptin with PTH and with biomarkers of bone turnover (serum beta crosslaps [CTX, a marker of bone resorption] and osteocalcin [OC, a marker of bone formation]) in 978 kidney transplant recipients. Associations were examined in multivariable regression models. Path analyses were used to determine if the association of leptin with bone turnover is independent of PTH. Higher leptin levels were associated with higher PTH and lower vitamin D levels, and adjustment for vitamin D attenuated the association between leptin and PTH. However, higher leptin was also significantly associated with lower levels of the bone turnover markers: 1 SD higher leptin was associated with 0.13 lower log-OC (-0.17, -0.08, P leptin with PTH was mostly mediated through vitamin D, and that the association between leptin and bone turnover was independent of PTH and vitamin D. Elevated leptin level is associated with lower bone turnover independent of its effects on serum PTH in kidney transplant recipients.

  1. THE EFFECT OF ORGANIZATIONAL CULTURE ON IT EMPLOYEES TURNOVER INTENTION IN ISRAEL

    Directory of Open Access Journals (Sweden)

    Kessler Ladelsky Limor

    2014-07-01

    Full Text Available Employee voluntary turnover is very expensive from the point of view of the organization, has significant negative effects on the organization and hence remains a critical issue for organizations.Most of the causes discussed in the literature are classic causes coming from conservative theories such as psychological and sociological organizational behavior etc. Field literature review shows that these general causes affecting voluntary turnover intention could be grouped in the following broad categories: 1 organizational causes, related to: Human Resource Management (HRM, organizational culture, job structure and content, leadership style and internal marketing strategies, policies and practices; 2 extra organizational causes, related to: individual characteristics and labor market aspects. One of the classical causes of voluntary turnover that has been researched but still needing attention is organizational culture. The purpose of this paper is to present a new explanation of the phenomenon of voluntary turnover of IT employees in the IT sector in Israel, i.e. from the corporate culture perspective. It focuses on the correlations between organizational culture and voluntary turnover intention among IT employees in Hi-Tech companies in Israel. This correlation was researched in an extensive empirical study among two population groups: IT employees and IT managers and by means of mixed methods research (combination of quantitative and qualitative research.The findings show that only one type of organizational culture influences voluntary turnover intention:Type C Marketing culture, which focuses on results and objectives. It is also shown that this type of organizational culture has a positive effect on voluntary turnover intention among IT employees in Hi-Tech companies in Israel. This finding has to be adopted by IT organizations and management who have to develop a way to prevent voluntary turnover among IT employees and have to develop an

  2. Nurse turnover: the mediating role of burnout.

    Science.gov (United States)

    Leiter, Michael P; Maslach, Christina

    2009-04-01

    This study tested whether the mediation model of burnout could predict nurses' turnover intentions. A better understanding of what factors support a commitment to a nursing career could inform both policies and workplace practices. The mediation model of burnout provides a way of linking the quality of a nurse's worklife to various outcomes, such as turnover. Data on areas of worklife, burnout, and turnover intentions were collected by surveying 667 Canadian nurses in the Atlantic Provinces. The findings supported the mediation model of burnout, in which areas of worklife predicted burnout, which in turn predicted turnover intentions. Cynicism was the key burnout dimension for turnover, and the most critical areas of worklife were value conflicts and inadequate rewards. The results of this study provide some new insights into how the intention of nurses to leave their job is related to particular aspects of their worklife and to burnout. These results suggest what may be the most appropriate areas to target for interventions to reduce the risk of nurses exiting early from their chosen career.

  3. Partial genetic turnover in Neandertals

    DEFF Research Database (Denmark)

    Dalén, Love; Orlando, Ludovic Antoine Alexandre; Shapiro, Beth

    2012-01-01

    Remarkably little is known about the population-level processes leading up to the extinction of the neandertal. To examine this, we use mtDNA sequences from 13 neandertal individuals, including a novel sequence from northern Spain, to examine neandertal demographic history. Our analyses indicate ...

  4. A Boom for Whom? Exploring the Impacts of a Rapid Increase in the Male Population Upon Women's Services in Darwin, Northern Territory.

    Science.gov (United States)

    Ennis, Gretchen; Tofa, Matalena; Finlayson, Mary; U'Ren, Julie

    2016-05-03

    A rapidly expanding natural-resource extraction industry and a growing military presence mean an increasingly male-skewed population for the city of Darwin, Australia. This has sparked concerns about the potential for increased violence against women. In this article, we present qualitative research detailing the views of 13 participants from 10 women's support services in the Darwin area. We argue that women's support services bear witness to and are tasked with responding to the impacts of population change on women, yet their work is undermined by uncertainties that stem from neoliberal funding rationales and limited demands on companies to address social issues. © The Author(s) 2016.

  5. Soil microbial carbon turnover decreases with increasing molecular size

    Science.gov (United States)

    Malik, Ashish; Gleixner, Gerd

    2014-05-01

    It is well established that soil microorganisms play an important role in respiration of newly fixed plant carbon. Recent results show that they also contribute significantly to soil organic matter (SOM) formation. We hypothesized that different molecular size classes of compounds in soil microbial biomass (SMB) have variable turnover time and in consequence influence SOM formation differentially. Here we used natural differences in carbon stable isotope signatures (δ13C values) after C3-C4 vegetation change to track newly fixed C4 plant carbon into SMB molecular size classes. SMB was obtained by chloroform fumigation extraction and δ13C values of its size classes were measured using size exclusion chromatography coupled online to liquid chromatography-isotope ratio mass spectrometry (SEC-LC-IRMS). Resolved SMB was assigned to 5 size classes: 1800-9800 Da, 800-1800 Da, 380-800 Da, 180-380 Da and 50-180 Da. The contribution of recent C4 plant carbon to size classes of SMB decreased with increasing molecular weight (MW). It ranged from 77±19% in the lowest MW size class size class to 41±14% in the 1800-9800 Da size class in 'Sandy' soil and from 59±18% in the lowest MW size class to 8±15% in the highest MW size class in 'Clayey' soil. A decreasing carbon turnover of compounds in SMB extracts along a continuum of molecular size from small to large implies that low molecular weight microbial compounds are rapidly metabolized products that link to fast respiratory carbon fluxes, whereas high molecular weight ones could be products of microbial synthesis like structural compounds that have slower turnover rates and link to slower SOM formation.

  6. Does Judge Turnover Affect Judicial Performance?

    DEFF Research Database (Denmark)

    Guerra, Alice; Tagliapietra, Claudio

    2017-01-01

    office to another after three years of mandate, and the law prescribes their transfer after ten years to guarantee their independence. Flaws in the process managing the backlog of outbound judges and the existence of asynchrony between outbound and inbound transfers produce a chain of delays...... to the disposition of court cases. Using a novel dataset on Court of Appeal Districts in Italy (2008–2012), we provide evidence of a strong negative relation between high turnover rates and judicial performance. We find that marginal increases in judge turnover rates lead to a statistically significant decrease...... in judicial performance over two years of time...

  7. Public health services and their relationship with rapid HIV test utilization and access for key populations in Morelos, Mexico

    Directory of Open Access Journals (Sweden)

    Carlos Jesús Conde González

    2015-07-01

    Full Text Available Objective. In 2009, 4 749 rapid HIV tests were run in Morelos, Mexico, despite lacking evidence on their results. This article seeks to analyze how public health organization relates to utility of rapid HIV test among healthcare users. Materials and methods. Joint study: comparison of differences in applied test and positive results for each group with the Bonferroni statistical tool, observational study in 34 health subsystems, and 11 interviews with public healthcare users. Results. Each subsystem processes influenced the use and usefulness of screening; for instance, primary care centers test only pregnant women and exclude men who have sex with men (MSM. That group shows significant differences (p<0.007 in the HIV-positive test with respect to other groups. Conclusions. Despite the availability of rapid detection tests and epidemiological evidence, the way public health services are organized impedes an efficient diagnosis in the group with higher risk, namely MSM. The distribution of rapid HIV tests was guided by stigmatization.

  8. Quantification of isotopic turnover in agricultural systems

    Science.gov (United States)

    Braun, A.; Auerswald, K.; Schnyder, H.

    2012-04-01

    The isotopic turnover, which is a proxy for the metabolic rate, is gaining scientific importance. It is quantified for an increasing range of organisms, from microorganisms over plants to animals including agricultural livestock. Additionally, the isotopic turnover is analyzed on different scales, from organs to organisms to ecosystems and even to the biosphere. In particular, the quantification of the isotopic turnover of specific tissues within the same organism, e.g. organs like liver and muscle and products like milk and faeces, has brought new insights to improve understanding of nutrient cycles and fluxes, respectively. Thus, the knowledge of isotopic turnover is important in many areas, including physiology, e.g. milk synthesis, ecology, e.g. soil retention time of water, and medical science, e.g. cancer diagnosis. So far, the isotopic turnover is quantified by applying time, cost and expertise intensive tracer experiments. Usually, this comprises two isotopic equilibration periods. A first equilibration period with a constant isotopic input signal is followed by a second equilibration period with a distinct constant isotopic input signal. This yields a smooth signal change from the first to the second signal in the object under consideration. This approach reveals at least three major problems. (i) The input signals must be controlled isotopically, which is almost impossible in many realistic cases like free ranging animals. (ii) Both equilibration periods may be very long, especially when the turnover rate of the object under consideration is very slow, which aggravates the first problem. (iii) The detection of small or slow pools is improved by large isotopic signal changes, but large isotopic changes also involve a considerable change in the input material; e.g. animal studies are usually carried out as diet-switch experiments, where the diet is switched between C3 and C4 plants, since C3 and C4 plants differ strongly in their isotopic signal. The

  9. Rapid assessment of genetic ancestry in populations of unknown origin by genome-wide genotyping of pooled samples.

    Directory of Open Access Journals (Sweden)

    Charleston W K Chiang

    2010-03-01

    Full Text Available As we move forward from the current generation of genome-wide association (GWA studies, additional cohorts of different ancestries will be studied to increase power, fine map association signals, and generalize association results to additional populations. Knowledge of genetic ancestry as well as population substructure will become increasingly important for GWA studies in populations of unknown ancestry. Here we propose genotyping pooled DNA samples using genome-wide SNP arrays as a viable option to efficiently and inexpensively estimate admixture proportion and identify ancestry informative markers (AIMs in populations of unknown origin. We constructed DNA pools from African American, Native Hawaiian, Latina, and Jamaican samples and genotyped them using the Affymetrix 6.0 array. Aided by individual genotype data from the African American cohort, we established quality control filters to remove poorly performing SNPs and estimated allele frequencies for the remaining SNPs in each panel. We then applied a regression-based method to estimate the proportion of admixture in each cohort using the allele frequencies estimated from pooling and populations from the International HapMap Consortium as reference panels, and identified AIMs unique to each population. In this study, we demonstrated that genotyping pooled DNA samples yields estimates of admixture proportion that are both consistent with our knowledge of population history and similar to those obtained by genotyping known AIMs. Furthermore, through validation by individual genotyping, we demonstrated that pooling is quite effective for identifying SNPs with large allele frequency differences (i.e., AIMs and that these AIMs are able to differentiate two closely related populations (HapMap JPT and CHB.

  10. Antecedents of Norwegian Beginning Teachers' Turnover Intentions

    Science.gov (United States)

    Tiplic, Dijana; Brandmo, Christian; Elstad, Eyvind

    2015-01-01

    This study aims at exploring several individual, organizational, and contextual factors that may affect beginning teachers' turnover intentions during their first years of practice. The sample consists of 227 beginning teachers (69% female and 31% male) from 133 schools in Norway. The results show four important antecedents of beginning teachers'…

  11. A Turnover Model for the Mexican Maquiladoras.

    Science.gov (United States)

    Maertz, Carl P.; Stevens, Michael J.; Campion, Michael A.

    2003-01-01

    From interviews with 47 Mexican maquiladora workers, a model of voluntary turnover was created and compared with models from the United States, Canada, England, and Australia. Despite similarities, the cultural and economic environment affected the precise content of antecedents in the Mexican model. (Contains 63 references.) (SK)

  12. Home Visitor Job Satisfaction and Turnover.

    Science.gov (United States)

    Buchbinder, Sharon B.; Duggan, Anne K.; Young, Elizabeth; Fuddy, Loretta; Sia, Cal

    This paper summarizes findings of a 3-year study of the job satisfaction and turnover of home visitors, both professional and paraprofessional, in programs which link families-at-risk for impaired functioning to medical home care and other resources. Specifically, the study examined: (1) home visitor personal characteristics that influence…

  13. Health care workplace discrimination and physician turnover.

    Science.gov (United States)

    Nunez-Smith, Marcella; Pilgrim, Nanlesta; Wynia, Matthew; Desai, Mayur M; Bright, Cedric; Krumholz, Harlan M; Bradley, Elizabeth H

    2009-12-01

    To examine the association between physician race/ ethnicity, workplace discrimination, and physician job turnover. Cross-sectional, national survey conducted in 2006-2007 of practicing physicians (n = 529) randomly identified via the American Medical Association Masterfile and the National Medical Association membership roster. We assessed the relationships between career racial/ethnic discrimination at work and several career-related dependent variables, including 2 measures of physician turnover, career satisfaction, and contemplation of career change. We used standard frequency analyses, odds ratios and chi2 statistics, and multivariate logistic regression modeling to evaluate these associations. Physicians who self-identified as nonmajority were significantly more likely to have left at least 1 job because of workplace discrimination (black, 29%; Asian, 24%; other race, 21%; Hispanic/Latino, 20%; white, 9%). In multivariate models, having experienced racial/ethnic discrimination at work was associated with high job turnover (adjusted odds ratio, 2.7; 95% CI, 1.4-4.9). Among physicians who experienced workplace discrimination, only 45% of physicians were satisfied with their careers (vs 88% among those who had not experienced workplace discrimination, p value workplace discrimination, p value Workplace discrimination is associated with physician job turnover, career dissatisfaction, and contemplation of career change. These findings underscore the importance of monitoring for workplace discrimination and responding when opportunities for intervention and retention still exist.

  14. University Lecturers' Professional Empowerment and Turnover in ...

    African Journals Online (AJOL)

    Hitherto, attention has not been paid to whether professional empowerment of the lecturers explains this phenomenon and whether it can help to curb it. Therefore, this study was conducted to analyse the level of professional empowerment provided to the lecturers and the way it relates to their turnover. Data was collected ...

  15. Climate change amplifies gross nitrogen turnover in montane grasslands of Central Europe in both summer and winter seasons.

    Science.gov (United States)

    Wang, Changhui; Chen, Zhe; Unteregelsbacher, Sebastian; Lu, Haiyan; Gschwendtner, Silvia; Gasche, Rainer; Kolar, Allison; Schloter, Michael; Kiese, Ralf; Butterbach-Bahl, Klaus; Dannenmann, Michael

    2016-09-01

    The carbon- and nitrogen-rich soils of montane grasslands are exposed to above-average warming and to altered precipitation patterns as a result of global change. To investigate the consequences of climatic change for soil nitrogen turnover, we translocated intact plant-soil mesocosms along an elevational gradient, resulting in an increase of the mean annual temperature by approx. 2 °C while decreasing precipitation from approx. 1500 to 1000 mm. Following three years of equilibration, we monitored the dynamics of gross nitrogen turnover and ammonia-oxidizing bacteria (AOB) and archaea (AOA) in soils over an entire year. Gross nitrogen turnover and gene levels of AOB and AOA showed pronounced seasonal dynamics. Both summer and winter periods equally contributed to cumulative annual N turnover. However, highest gross N turnover and abundance of ammonia oxidizers were observed in frozen soil of the climate change site, likely due to physical liberation of organic substrates and their rapid turnover in the unfrozen soil water film. This effect was not observed at the control site, where soil freezing did not occur due to a significant insulating snowpack. Climate change conditions accelerated gross nitrogen mineralization by 250% on average. Increased N mineralization significantly stimulated gross nitrification by AOB rather than by AOA. However, climate change impacts were restricted to the 2-6 cm topsoil and rarely occurred at 12-16 cm depth, where generally much lower N turnover was observed. Our study shows that significant mineralization pulses occur under changing climate, which is likely to result in soil organic matter losses with their associated negative impacts on key soil functions. We also show that N cycling processes in frozen soil can be hot moments for N turnover and thus are of paramount importance for understanding seasonal patterns, annual sum of N turnover and possible climate change feedbacks. © 2016 John Wiley & Sons Ltd.

  16. Denitrification, nitrate turnover, and aerobic respiration by benthic foraminiferans in the oxygen minimum zone off Chile

    DEFF Research Database (Denmark)

    Høgslund, Signe; Revsbech, Niels Peter; Cedhagen, Tomas

    2008-01-01

    Population density, nitrate turnover, and oxygen respiration of benthic foraminiferans were investigated in the oxygen minimum zone (OMZ) off the Chilean coast. Live foraminiferans were found predominantly in the upper 3 mm of the sediment, and the nitrate accumulating species Nonionella cf. stel...

  17. Population dynamics of Empetrum hermaphroditum (Ericaceae) on a subarctic sand dune: Evidence of rapid colonization through efficient sexual reproduction.

    Science.gov (United States)

    Boudreau, Stéphane; Ropars, Pascale; Harper, Karen Amanda

    2010-05-01

    The importance of sexual reproduction for clonal plant species has long been underestimated, perhaps as a consequence of the difficulty in identifying individuals, preventing the study of their population dynamics. Such is the case for Empetrum hermaphroditum, an ericaceous species, which dominates the ground vegetation of subarctic ecosystems. Despite abundant seed production, seedlings are rarely observed. Therefore, prevalent seedling recruitment on a subarctic dune system provided an opportunity to study the population dynamics and spatial pattern of the colonization phase of this species. We established a 6-ha grid on the dune systems that extended from the shoreline to the fixed dunes and mapped and measured all E. hermaphroditum individuals in the grid. Moreover, we sampled 112 individuals just outside the grid to identify any allometric relationship between the size and age of the individuals, which allowed us to reconstruct population expansion. The overall size structure suggests that the population is still expanding. In the last 50 yr, E. hermaphroditum advanced more than 200 m in the dune system. Expansion started in the 1960s simultaneously at different distances from the shoreline. Colonization did not proceed gradually from the fixed dune toward the shoreline but instead individuals established earlier in the troughs between the dunes, with an increasingly clumped spatial pattern as the population filled in with time.

  18. Assessing service use for mental health by Indigenous populations in Australia, Canada, New Zealand and the United States of America: a rapid review of population surveys.

    Science.gov (United States)

    McIntyre, Cecily; Harris, Meredith G; Baxter, Amanda J; Leske, Stuart; Diminic, Sandra; Gone, Joseph P; Hunter, Ernest; Whiteford, Harvey

    2017-08-04

    Indigenous people in Australia, Canada, New Zealand and the United States of America experience disproportionately poor mental health compared to their non-Indigenous counterparts. To optimally allocate resources, health planners require information about the services Indigenous people use for mental health, their unmet treatment needs and the barriers to care. We reviewed population surveys of Indigenous people to determine whether the information needed to guide service development is being collected. We sought national- or state-level epidemiological surveys of Indigenous populations conducted in each of the four selected countries since 1990 that asked about service use for mental health. Surveys were identified from literature reviews and web searches. We developed a framework for categorising the content of each survey. Using this framework, we compared the service use content of the surveys of Indigenous people to each other and to general population mental health surveys. We focused on identifying gaps in information coverage and topics that may require Indigenous-specific questions or response options. Nine surveys met our inclusion criteria. More than half of these included questions about health professionals consulted, barriers to care, perceived need for care, medications taken, number, duration, location and payment of health professional visits or use of support services or self-management. Less than half included questions about interventions received, hospital admissions or treatment dropout. Indigenous-specific content was most common in questions regarding use of support services or self-management, types of health professionals consulted, barriers to care and interventions received. Epidemiological surveys measuring service use for mental health among Indigenous populations have been less comprehensive and less standardised than surveys of the general population, despite having assessed similar content. To better understand the gaps in mental

  19. Cesium-134 and strontium-85 turnover rates in the centipede Scolopocryptops nigridia McNeill

    Energy Technology Data Exchange (ETDEWEB)

    Yates, L R; Crossley, Jr, D A

    1979-07-01

    Radioactive tracers are providing significant information about the ecology of food chains, including such phenomena as accumulation of radioactive fission products, movement of materials along food chains, assimilation and ingestion rates, and nutrient accumulation and turnover. In this study the ingestion, assimilation and turnover to two radioactive tracers were investigated for Scolopocryptops nigridia, an abundant species in forests of the southeastern United States. The two tracers utilized, cesium-134 and strontium-85, are metabolic analogs of potassium and calcium, respectively. The research was performed as part of a larger investigation on the population ecology of the centipede species, emphasizing its relations to nutrient cycling and energy flow in a forest floor system.

  20. Carboxylesterase 1A2 encoding gene with increased transcription and potential rapid drug metabolism in Asian populations

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Berg; Madsen, Majbritt Busk; Lyauk, Yassine Kamal

    2017-01-01

    The carboxylesterase 1 gene (CES1) encodes a hydrolase implicated in the metabolism of commonly used drugs. CES1A2, a hybrid of CES1 and a CES1-like pseudogene, has a promoter that is weak in most individuals. However, some individuals harbor a promoter haplotype of this gene with two overlapping...... Sp1 sites that confer significantly increased transcription potentially leading to rapid drug metabolism. This CES1A2 haplotype has previously been reported to be common among Asians. Using polymerase chain reaction followed by sequencing, the present study examined variation in the promoter and 5...

  1. Rapidly increasing body mass index among children, adolescents and young adults in a transitioning population, South Africa, 2008-15

    DEFF Research Database (Denmark)

    Sartorius, B; Sartorius, K; Taylor, M

    2017-01-01

    budget. Our refined understanding highlights that risks are further compounded for certain groups/places, and emphasizes that urgent geographical and population-targeted interventions are necessary. These interventions could include a sugar tax, clearer food labelling, revised school feeding programmes...

  2. Rapid increase in log populations in drought-stressed mixed-conifer and ponderosa pine forests in northern Arizona

    Science.gov (United States)

    Joseph L. Ganey; Scott C. Vojta

    2012-01-01

    Down logs provide important ecosystem services in forests and affect surface fuel loads and fire behavior. Amounts and kinds of logs are influenced by factors such as forest type, disturbance regime, forest man-agement, and climate. To quantify potential short-term changes in log populations during a recent global- climate-change type drought, we sampled logs in mixed-...

  3. Development of a rapid multiplex SSR genotyping method to study populations of the fun-gal plant pathogen Zymoseptoria tritici

    NARCIS (Netherlands)

    Gautier, A.; Marcel, T.C.; Confais, J.; Crane, C.; Kema, G.H.J.; Suffert, F.; Walker, A.S.

    2014-01-01

    Background Zymoseptoria tritici is a hemibiotrophic ascomycete fungus causing leaf blotch of wheat that often decreases yield severely. Populations of the fungus are known to be highly diverse and poorly differentiated from each other. However, a genotyping tool is needed to address further

  4. Development of a rapid multiplex SSR genotyping method to study populations of the fungal plant pathogen Zymoseptoria tritici.

    Science.gov (United States)

    Gautier, Angélique; Marcel, Thierry C; Confais, Johann; Crane, Charles; Kema, Gert; Suffert, Frédéric; Walker, Anne-Sophie

    2014-06-18

    Zymoseptoria tritici is a hemibiotrophic ascomycete fungus causing leaf blotch of wheat that often decreases yield severely. Populations of the fungus are known to be highly diverse and poorly differentiated from each other. However, a genotyping tool is needed to address further questions in large collections of isolates, regarding regional population structure, adaptation to anthropogenic selective pressures, and dynamics of the recently discovered accessory chromosomes. This procedure is limited by costly and time-consuming simplex PCR genotyping. Recent development of genomic approaches and of larger sets of SSRs enabled the optimization of microsatellite multiplexing. We report here a reliable protocol to amplify 24 SSRs organized in three multiplex panels, and covering all Z. tritici chromosomes. We also propose an automatic allele assignment procedure, which allows scoring alleles in a repeatable manner across studies and laboratories. All together, these tools enabled us to characterize local and worldwide populations and to calculate diversity indexes consistent with results reported in the literature. This easy-to-use, accurate, repeatable, economical, and faster technical strategy can provide useful genetic information for evolutionary inferences concerning Z. tritici populations. Moreover, it will facilitate the comparison of studies from different scientific groups.

  5. Turnover of sex chromosomes in the stickleback fishes (gasterosteidae.

    Directory of Open Access Journals (Sweden)

    Joseph A Ross

    2009-02-01

    Full Text Available Diverse sex-chromosome systems are found in vertebrates, particularly in teleost fishes, where different systems can be found in closely related species. Several mechanisms have been proposed for the rapid turnover of sex chromosomes, including the transposition of an existing sex-determination gene, the appearance of a new sex-determination gene on an autosome, and fusions between sex chromosomes and autosomes. To better understand these evolutionary transitions, a detailed comparison of sex chromosomes between closely related species is essential. Here, we used genetic mapping and molecular cytogenetics to characterize the sex-chromosome systems of multiple stickleback species (Gasterosteidae. Previously, we demonstrated that male threespine stickleback fish (Gasterosteus aculeatus have a heteromorphic XY pair corresponding to linkage group (LG 19. In this study, we found that the ninespine stickleback (Pungitius pungitius has a heteromorphic XY pair corresponding to LG12. In black-spotted stickleback (G. wheatlandi males, one copy of LG12 has fused to the LG19-derived Y chromosome, giving rise to an X(1X(2Y sex-determination system. In contrast, neither LG12 nor LG19 is linked to sex in two other species: the brook stickleback (Culaea inconstans and the fourspine stickleback (Apeltes quadracus. However, we confirmed the existence of a previously reported heteromorphic ZW sex-chromosome pair in the fourspine stickleback. The sex-chromosome diversity that we have uncovered in sticklebacks provides a rich comparative resource for understanding the mechanisms that underlie the rapid turnover of sex-chromosome systems.

  6. Accelerated extracellular matrix turnover during exacerbations of COPD

    DEFF Research Database (Denmark)

    Sand, Jannie M B; Knox, Alan J; Lange, Peter

    2015-01-01

    progression. Extracellular matrix (ECM) turnover reflects activity in tissues and consequently assessment of ECM turnover may serve as biomarkers of disease activity. We hypothesized that the turnover of lung ECM proteins were altered during exacerbations of COPD. METHODS: 69 patients with COPD hospitalised...

  7. Library infrastructure as predictor of turnover intentions of librarians ...

    African Journals Online (AJOL)

    The result revealed that library infrastructure is a predictor of turnover intentions of librarians (r = 0.647, p < 0.05) which indicates that an improvement in library infrastructure will reduce turnover intentions of librarians. The result showed that inadequate/unavailability of library infrastructure increase turnover intentions of ...

  8. Rapid changes in key ruminal microbial populations during the induction of and recovery from diet-induced milk fat depression in dairy cows.

    Science.gov (United States)

    Rico, D E; Preston, S H; Risser, J M; Harvatine, K J

    2015-08-14

    The ruminant provides a powerful model for understanding the temporal dynamics of gastrointestinal microbial communities. Diet-induced milk fat depression (MFD) in the dairy cow is caused by rumen-derived bioactive fatty acids, and is commonly attributed to the changes in the microbial population. The aim of the present study was to determine the changes occurring in nine ruminal bacterial taxa with well-characterised functions, and abundance of total fungi, ciliate protozoa and bacteria during the induction of and recovery from MFD. Interactions between treatment and time were observed for ten of the twelve populations. The total number of both fungi and ciliate protozoa decreased rapidly (days 4 and 8, respectively) by more than 90% during the induction period and increased during the recovery period. The abundance of Streptococcus bovis (amylolytic) peaked at 350% of control levels on day 4 of induction and rapidly decreased during the recovery period. The abundance of Prevotella bryantii (amylolytic) decreased by 66% from day 8 to 20 of the induction period and increased to the control levels on day 12 of the recovery period. The abundance of Megasphaera elsdenii and Selenomonas ruminantium (lactate-utilising bacteria) increased progressively until day 12 of induction (>170%) and decreased during the recovery period. The abundance of Fibrobacter succinogenes (fibrolytic) decreased by 97% on day 4 of induction and increased progressively to an equal extent during the recovery period, although smaller changes were observed for other fibrolytic bacteria. The abundance of the Butyrivibrio fibrisolvens/Pseudobutyrivibrio group decreased progressively during the induction period and increased during the recovery period, whereas the abundance of Butyrivibrio hungatei was not affected by treatment. Responsive taxa were modified rapidly, with the majority of changes occurring within 8 d and their time course was similar to the time course of the induction of MFD

  9. Populism

    OpenAIRE

    Abts, Koenraad; Van Kessel, Stijn

    2015-01-01

    Populism is a concept applied to a wide range of political movements and actors across the globe. There is, at the same time, considerable confusion about the attributes and manifestation of populism, as well as its impact on democracy. This contribution identifies the defining elements of the populist ideology and discusses the varieties in which populism manifests itself, for instance as a component of certain party families. We finally discuss various normative interpretations of populism,...

  10. Factors influencing turnover intention among primary care doctors: a cross-sectional study in Chongqing, China.

    Science.gov (United States)

    Wen, Tong; Zhang, Yan; Wang, Xue; Tang, Guo

    2018-02-13

    The intention to leave a job, known as turnover intention, among primary care doctors has a significant impact on primary health care service delivery. We investigated primary care doctors' turnover intention and analysed associated factors involved in primary health facilities in Chongqing, China. A total of 440 doctors were interviewed, they were selected using a multi-stage stratified random sampling method. The survey instrument was a self-administered questionnaire which assessed socio-demographic and work-related characteristics, job satisfaction and turnover intention. The data were analysed using χ 2 test, one-way analysis of variance, exploratory factor analysis and linear regression analysis. Our study found that 42.3% of the primary care doctors we sampled in Chongqing, China, intended to resign. Location, age, job title, doctor's position level, work pressure and job satisfaction were associated with turnover intention. Job satisfaction included both employment-related job satisfaction (including "your chance of promotion", "your rate of pay" and two other items) and satisfaction with the job itself (including "the freedom to choose your own method of working", "your job safety" and two other items). Improving job satisfaction, in terms of salary, promotion and job safety, is crucial for reducing turnover intention among primary care doctors. Therefore, we suggest that the government increase its financial investment in primary care facilities, especially in less-developed areas, and reform incentive mechanisms to improve the job satisfaction of primary care doctors. The government should consider policies such as establishing a social pension programme for village-level doctors and providing more opportunities for job promotion among primary care doctors, especially township-level doctors. Attention should also be paid to the impact of rapid urbanization, which could lead to increased workload or increased opportunities for career development, thus

  11. Bone mass and turnover in fibromyalgia

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Gam, A; Egsmose, C

    1993-01-01

    Physical inactivity accelerates bone loss. Since patients with fibromyalgia are relatively physically inactive, bone mass and markers of bone metabolism were determined in 12 premenopausal women with fibromyalgia and in healthy age matched female control subjects. No differences were found in lum.......01. This was linked to lower urinary creatinine excretion (p = 0.02) probably reflecting lower physical activity in the patients with fibromyalgia. We conclude that bone mass and turnover are generally not affected in premenopausal women with fibromyalgia....

  12. Bone mass and turnover in fibromyalgia

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Gam, A; Egsmose, C

    1993-01-01

    Physical inactivity accelerates bone loss. Since patients with fibromyalgia are relatively physically inactive, bone mass and markers of bone metabolism were determined in 12 premenopausal women with fibromyalgia and in healthy age matched female control subjects. No differences were found.......01. This was linked to lower urinary creatinine excretion (p = 0.02) probably reflecting lower physical activity in the patients with fibromyalgia. We conclude that bone mass and turnover are generally not affected in premenopausal women with fibromyalgia....

  13. High bone turnover in Irish professional jockeys.

    LENUS (Irish Health Repository)

    Waldron-Lynch, F

    2012-02-01

    SUMMARY: Professional jockeys are routinely exposed to high impact trauma and sustain fractures frequently. We found that jockeys restrict their caloric intake in order to maintain regulation weights, and that bone turnover is high. There are significant health and safety implications for the racing industry. INTRODUCTION: Professional jockeys routinely sustain fractures from high impact falls. Jockeys maintain a low percentage body fat and a low body mass index (BMI) to achieve low weight targets in order to race. We evaluated dietary habits and bone metabolism in jockeys. METHODS: Bone mineral density (BMD) was measured in 27 male jockeys of the 144 jockeys licensed in Ireland. Fourteen (52%) had BMD T score below -1.0, of whom 12 consented to clinical review, nutritional survey, endocrine studies, and bone turnover markers (BTM). BTM were compared to age- and sex-matched controls (n = 16). RESULTS: BMI was 20.6 +\\/- 1.7 kg\\/m(2); previous fracture frequency was 3.2 +\\/- 2.0 per rider. All had normal endocrine axes. The jockeys\\' diet as determined by a 7-day dietary recall was deficient in energy, calcium, and vitamin D intake. Compared with the control group, the jockey group had evidence of increased bone turnover. CONCLUSIONS: A substantial proportion of the professional jockeys in Ireland have low-normal BMD, low BMI, and high bone turnover that may result from weight and dietary restrictions. These factors seem to have a deleterious effect on their bone health and predispose the jockeys to a high fracture risk that should be remediated.

  14. TURNOVER AND JOB EMBEDDEDNESS IN TIJUANA MEXICO

    OpenAIRE

    Blanca Rosa García Rivera; Peter W Hom; Ignacio Alejandro Mendoza Martínez; Sonia Elizabeth Maldonado Radillo; Concepción Ramírez Barón

    2013-01-01

    In this paper we analyze the relationship between family and community links and future intentions to quit from employees at the export processing zone (EPZ) in Tijuana, Mexico. With survey data gathered in an organization belonging to a Tijuana EPZ, we applied the theory of embededdness to identify the causes behind turnover. A questionnaire with 125 items using a 4-points Likert scale was developed to assess job embeddedness, family embeddedness, satisfaction with benefits, and affective co...

  15. Differential turnover of tyrosinated and detyrosinated microtubules.

    OpenAIRE

    Webster, D. R.; Gundersen, G G; Bulinski, J C; Borisy, G G

    1987-01-01

    Turnover of tyrosinated and detyrosinated microtubules ([Tyr]MTs and [Glu]MTs, respectively) was analyzed by the combined use of hapten-mediated immunocytochemistry and peptide-specific antibodies. Cells were microinjected with hapten-labeled tubulin and then processed for triple-label immunofluorescence to determine the pattern of incorporation of the injected subunits into [Tyr]- and [Glu]-MTs. Within 2 min of microinjection, hapten-labeled domains were present at the ends of virtually all ...

  16. Rapid differentiation of Listeria monocytogenes epidemic clones III and IV and their intact compared with heat-killed populations using Fourier transform infrared spectroscopy and chemometrics.

    Science.gov (United States)

    Nyarko, Esmond B; Puzey, Kenneth A; Donnelly, Catherine W

    2014-06-01

    The objectives of this study were to determine if Fourier transform infrared (FT-IR) spectroscopy and multivariate statistical analysis (chemometrics) could be used to rapidly differentiate epidemic clones (ECs) of Listeria monocytogenes, as well as their intact compared with heat-killed populations. FT-IR spectra were collected from dried thin smears on infrared slides prepared from aliquots of 10 μL of each L. monocytogenes ECs (ECIII: J1-101 and R2-499; ECIV: J1-129 and J1-220), and also from intact and heat-killed cell populations of each EC strain using 250 scans at a resolution of 4 cm(-1) in the mid-infrared region in a reflectance mode. Chemometric analysis of spectra involved the application of the multivariate discriminant method for canonical variate analysis (CVA) and linear discriminant analysis (LDA). CVA of the spectra in the wavelength region 4000 to 600 cm(-1) separated the EC strains while LDA resulted in a 100% accurate classification of all spectra in the data set. Further, CVA separated intact and heat-killed cells of each EC strain and there was 100% accuracy in the classification of all spectra when LDA was applied. FT-IR spectral wavenumbers 1650 to 1390 cm(-1) were used to separate heat-killed and intact populations of L. monocytogenes. The FT-IR spectroscopy method allowed discrimination between strains that belong to the same EC. FT-IR is a highly discriminatory and reproducible method that can be used for the rapid subtyping of L. monocytogenes, as well as for the detection of live compared with dead populations of the organism. Fourier transform infrared (FT-IR) spectroscopy and multivariate statistical analysis can be used for L. monocytogenes source tracking and for clinical case isolate comparison during epidemiological investigations since the method is capable of differentiating epidemic clones and it uses a library of well-characterized strains. The FT-IR method is potentially less expensive and more rapid compared to genetic

  17. A rapid and sensitive GC-MS/MS method to measure deuterium labeled deoxyadenosine in DNA from limited mouse cell populations

    Science.gov (United States)

    Farthing, Don E.; Buxbaum, Nataliya P.; Bare, Catherine V.; Treadwell, Shirin M.; Kapoor, Veena; Williams, Kirsten M.; Gress, Ronald E.

    2013-01-01

    A rapid and sensitive GC-MS/MS method was developed to quantitatively measure low levels of DNA base deoxyadenosine (dA) and its isotopologues (e.g. dA M+1) from limited mouse cell populations. Mice undergoing allogeneic hematopoietic transplantation (AHSCT) received deuterated water at biologically relevant time intervals post AHSCT, allowing labeling of DNA upon cell division, which was detected as the dA M+1 isotopologue. Targeted mouse cell populations were isolated from lymphoid organs and purified by multi-parameter fluorescence activated cell sorting. Cell lysis, DNA extraction and hydrolysis were accomplished using available commercial procedures. The novel analytical method utilized a hydrophilic-lipophilic balanced sample preparation, rapid on-line hot GC inlet gas phase sample derivatization, fast GC low thermal mass technology, and a recently marketed GC-MS/MS system. Calibration standards containing dA and fortified with relevant levels of dA M+1 (0.25–20%) and dA M+5 (internal standard) were used for sample quantitation. The method employed a quadratic fit for calibration of dA M+1 (0.25–20%) and dA, demonstrated excellent accuracy and precision, and had limits of detection of 100 fg on-column for the dA isotopologues. The method was validated and required only 20,000 cells to characterize population dynamics of cells involved in the biology of chronic graft-versus-host disease, the main cause of late morbidity and non-relapse-mortality following AHSCT. The high sensitivity and specificity of the method makes it useful for investigating in vivo kinetics on limited and important cell populations (e.g. T regulatory cells) from disease conditions or in disease models that are immune-mediated, such as diabetes, HIV/AIDS, arthritis, inflammatory bowel disease, and multiple sclerosis. PMID:23541182

  18. Generational differences in registered nurse turnover.

    Science.gov (United States)

    LeVasseur, Sandra A; Wang, Chen-Yen; Mathews, Barbara; Boland, Mary

    2009-08-01

    The chronic nature of the nursing workforce shortage in the United States is a continuing concern. As the nationwide gap between supply and demand grows, it remains unknown what impact turnover will have on nursing, access to care, and efforts to improve quality and safety of health care. It also remains unclear whether the recent turnover trends among new graduate registered nurses differ from past generational cohorts of new nurses. The aims of this study were to identify the reasons why registered nurses turnover by generational cohort (Veterans, Baby Boomers, and GenXMs) and to compare the length of time nurses were employed in their first five nursing positions by generational cohort. The findings suggest the three generational cohorts displayed similar reasons for leaving nursing positions with relocation, career advancement, and personal/family reasons reported most frequently. Except for the first nursing position, significant generational effects were found in the length of time Veterans, Baby Boomer, and GenXMs stayed employed in their nursing positions. It remains unknown why the GenXMs displayed a significantly shorter length of employment time in their second, third, fourth, and fifth nursing positions. The decline in length of employment time displayed in both the Baby Boomers and GenXMs may be an issue of concern requiring future research.

  19. PERAN STRES KERJA DAN KEPUASAN KERJA UNTUK MENGURANGI TURNOVER INTENTION

    Directory of Open Access Journals (Sweden)

    Syarifah Nazenin

    2014-09-01

    Full Text Available Tujuan penelitian ini untuk menguji pengaruh variabel stres kerja dan kepuasan kerja pada turnover intention karyawan tetap bagian produksi. Sampel penelitian ini adalah 86 responden, menggunakan metode Slovin dengan teknik probability sampling dengan jenis proportionate random sampling. Berdasarkan hasil penelitian, menunjukkan bahwa stres kerja berpengaruh positif signifikan pada turnover intention. Kemudian, kepuasan kerja berpengaruh negatif signifikan. Penelitian ini menyimpulkan, bahwa stres kerja berpengaruh positif dan signifikan pada turnover intention karyawan dan kepuasan kerja berpengaruh negatif dan signifikan terhadap turnover intention karyawan. Implikasi manajerial yang bisa dilakukan adalah dengan pengurangan tingkat stres karyawan dan membuat program untuk tujuan menekan turnover intention, seperti kesempatan promosi dan meningkatkan reward karyawan. The purpose of this study conducted to examine the effect of work stress and job satisfaction on turnover intention of employee in production department. The sample was 86 respondent, using Slovin method with proportionate random sampling technique. The result showed that job stress has a positive effect on turnover intention while job satisfaction has a negative effect on turnover intention. This study conclude that job stress has positive and significant impact on employee turnover intention and job satisfaction significantly and negatively related to turnover intention of employees. Therefore, it is recommended to managerial level people to reduce stress levels in employees and to create a program for pressing turnover intention, such as promotional opportunities and improve employee rewards.

  20. High incidence of community-acquired pneumonia among rapidly aging population in Japan: a prospective hospital-based surveillance.

    Science.gov (United States)

    Takaki, Masahiro; Nakama, Takahiro; Ishida, Masayuki; Morimoto, Hitomi; Nagasaki, Yuka; Shiramizu, Rina; Hamashige, Naohisa; Chikamori, Masayuki; Yoshida, Laymyint; Ariyoshi, Koya; Suzuki, Motoi; Morimoto, Konosuke

    2014-01-01

    The age-group-specific incidence and etiological patterns of community-acquired pneumonia (CAP) have not been fully established in Japan. A 2-year prospective surveillance was conducted in Kochi city, Western Japan. All CAP patients aged ≥15 years who visited a community-based hospital were enrolled in the study. Clinical samples were examined by conventional bacterial culture and urinary antigen tests, and 6 bacterial pathogens and 16 respiratory viruses were identified from sputum samples by multiplex polymerase chain reaction assays. The age-group-specific incidence of CAP was estimated using a population-based data set of the total number of outpatients in the whole city. Ninety of the 131 enrolled patients, 68.7% were positive for respiratory pathogens. Streptococcus pneumoniae was the leading bacterial pathogen identified (28.2%). Respiratory viruses were identified in 36 patients (27.5%), and human entero-rhinovirus was the most common (13.3%) among them. The estimated overall incidence of adult CAP in Kochi was 9.6 per 1,000 person-years (PY); the estimated age group-specific incidence was 3.4, 10.7, and 42.9 per 1,000 PY for those aged 15-64, 65-74, and ≥75 years, respectively. The high incidence of CAP in these rural city of Japan, probably reflects the substantial aged population. S. pneumoniae and respiratory viruses play important roles in CAP in all age groups.

  1. Turnover and organizational performance: a comparative analysis of the effects of voluntary, involuntary, and reduction-in-force turnover.

    Science.gov (United States)

    McElroy, J C; Morrow, P C; Rude, S N

    2001-12-01

    Data were collected from 31 regional subunits of a national financial services company to examine differential effects of 3 types of turnover (voluntary, involuntary, and reduction-in-force) on measures of organizational subunit performance. Although each form of turnover exhibited adverse effects on subunit performance when examined separately, partial correlation results revealed greater and more pervasive adverse effects for reduction-in-force turnover (i.e., downsizing) in comparison with the effects of voluntary and involuntary turnover. The results confirm the negative effects of downsizing, suggesting the need to move beyond the traditional voluntary-involuntary classification scheme used in turnover research.

  2. Rapid impact of rotavirus vaccine introduction to the National Immunization plan in southern Israel: comparison between 2 distinct populations.

    Science.gov (United States)

    Givon-Lavi, Noga; Ben-Shimol, Shalom; Cohen, Raanan; Greenberg, David; Dagan, Ron

    2015-04-15

    Rotavirus vaccines were licensed in Israel in 2007, and in 2011 the pentavalent-vaccine (RV5) was introduced into the Israeli National Immunization plan. To determine the effect of rotavirus-vaccines on the incidence of hospital visits due to rotavirus gastroenteritis (RVGE) and all-cause diarrhea in Jewish and Bedouin children vaccine period, the overall RVGE hospital visits rates per 1000 in children Vaccine uptake was faster in the Jewish vs. the Bedouin population. In the year following RV5 introduction, RVGE hospital visits rates declined by 82%, 70% (Pvaccine introduction in southern Israel in both Jewish and Bedouin children. However, the impact was faster and more profound in Jewish children, probably related to higher vaccine uptake and possibly to lifestyle differences. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. A survey of a population of anaesthesiologists from South India regarding practices for rapid sequence intubation in patients with head injury

    Directory of Open Access Journals (Sweden)

    Satyen Parida

    2016-01-01

    Full Text Available Background and Aims: Evidence and utility of the individual steps of the rapid sequence induction and tracheal intubation protocols have been debated, especially in the setting of traumatic brain injury. The purpose of this survey was to determine preferences in the current approach to rapid sequence intubation ( RSI in head injury patients among a population of anaesthesiologists from South India. Methods: A questionnaire was E-mailed to all the members of the Indian Society of Anaesthesiologists′ South Zone Chapter to ascertain their preferences, experience and comfort level with regard to their use of rapid sequence intubation techniques in adult patients with head injury. Participants were requested to indicate their practices for RSI technique for a head-injured patient upon arrival at the Emergency Medical Services department of their hospital. Results: The total response rate was 56.9% (530/932. Of the total respondents, 35% of the clinicians used cricoid pressure routinely, most respondents (68% stated that they pre-oxygenate the patients for about 3 min prior to RSI, thiopentone (61% and propofol (34% were commonly used prior to intubation. Rocuronium was the muscle relaxant of choice for RSI among the majority (44%, compared to succinylcholine (39%. Statistical analyses were performed after the initial entry onto a spreadsheet. Data were summarised descriptively using frequency distribution. Conclusion: In a rapid sequence intubation situation, the practice differed significantly among anaesthesiologists. Owing to disagreements and paucity of evidence-based data regarding the standards of RSI, it is apparent that RSI practice still has considerable variability in clinical practice.

  4. Turnover of grain legume N rhizodeposits and effect of rhizodeposition on the turnover of crop residues

    DEFF Research Database (Denmark)

    Mayer, J.; Buegger, F.; Jensen, E.S.

    2004-01-01

    The turnover of N derived from rhizodeposition of faba bean (Vicia faba L.), pea (Pisum sativum L.) and white lupin (Lupinus albus L.) and the effects of the rhizodeposition on the subsequent C and N turnover of its crop residues were investigated in an incubation experiment (168 days, 15 degrees....... In the experiment the turnover of C and N was compared in soils with and without previous growth of three legumes and with and without incorporation of crop residues. After 168 days, 21% (lupin), 26% (faba bean) and 27% (pea) of rhizodeposition N was mineralised in the treatments without crop residues. A smaller......C). A sandy loam soil for the experiment was either stored at 6 degreesC or planted with the respective grain legume in pots. Legumes were in situ N-15 stem labelled during growth and visible roots were removed at maturity. The remaining plant-derived N in soil was defined as N rhizodeposition...

  5. Investigating the low-mass slope and possible turnover in the LMC IMF

    Science.gov (United States)

    Gennaro, Mario

    2014-10-01

    We propose to derive the Initial Mass Function (IMF) of the field population of the Large Magellanic Cloud (LMC) down to 0.2 solar masses, probing the mass regime where the characteristic IMF turnover is observed in our Galaxy. The power of the HST, using the WFC3 IR channel, is necessary to obtain photometric mass estimates for the faint, cool, dwarf stars with masses below the expected IMF turnover point. Only by probing the IMF down to such masses, it will be possible to clearly distinguish between a bottom-heavy or bottom-light IMF in the LMC. Recent studies, using the deepest available observations for the Small Magellanic Cloud, cannot find clear evidence of a turnover in the IMF for this galaxy, suggesting a bottom-heavy IMF in contrast to the Milky Way. A similar study of the LMC is needed to confirm a possible dependence of the low-mass IMF with galactic environment. Studies of giant ellipticals have recently challenged the picture of a universal IMF, and suggest an enviromental dependence of the IMF, with the most massive galaxies having a larger fraction of low mass stars and no IMF turnover. A study of possible IMF variations from resolved stellar populations in nearby galaxies is of great importance in sheding light on this issue. Our simple approach, using direct evidence from basic star counts, is much less prone to systematic errors with respect to studies of more distant objects which have to rely on the observations of integrated properties.

  6. Coupled Model of Artificial Neural Network and Grey Model for Tendency Prediction of Labor Turnover

    Directory of Open Access Journals (Sweden)

    Yueru Ma

    2014-01-01

    Full Text Available The tendency of labor turnover in the Chinese enterprise shows the characteristics of seasonal fluctuations and irregular distribution of various factors, especially the Chinese traditional social and cultural characteristics. In this paper, we present a coupled model for the tendency prediction of labor turnover. In the model, a time series of tendency prediction of labor turnover was expressed as trend item and its random item. Trend item of tendency prediction of labor turnover is predicted using Grey theory. Random item of trend item is calculated by artificial neural network model (ANN. A case study is presented by the data of 24 months in a Chinese matured enterprise. The model uses the advantages of “accumulative generation” of a Grey prediction method, which weakens the original sequence of random disturbance factors and increases the regularity of data. It also takes full advantage of the ANN model approximation performance, which has a capacity to solve economic problems rapidly, describes the nonlinear relationship easily, and avoids the defects of Grey theory.

  7. Cereal aphid colony turnover and persistence in winter wheat.

    Directory of Open Access Journals (Sweden)

    Linton Winder

    Full Text Available An understanding of spatial and temporal processes in agricultural ecosystems provides a basis for rational decision-making with regards to the management and husbandry of crops, supporting the implementation of integrated farming strategies. In this study we investigated the spatial and temporal distribution of aphid pests (Sitobion avenae and Metopolophium dirhodum within winter wheat fields. Using an intensive sampling programme we investigated distributions at both the small (single shoot and large (field scales. Within two fields, a grid with 82 locations was established (area 120 m by 168 m. At each location, 25 shoots were individually marked and aphid counts by observation conducted on 21 and 22 occasions as the crop matured, resulting in 43,050 and 45,100 counts being conducted in the two fields respectively. We quantified field scale spatial distributions, demonstrating that spatial pattern generally emerged, with temporal stability being both species- and field- dependent. We then measured turnover of colonies at the small (individual shoot and large (field scales by comparing consecutive pairs of sampling occasions. Four turnover categories were defined: Empty (no aphids recorded on either occasion; Colonised (aphids recorded on the second occasion but not the first; Extinction (aphids recorded on the first occasion but not the second; Stable (aphids recorded on both occasions. At the field scale, population stability soon established, but, at the small scale there was a consistently high proportion of unoccupied shoots with considerable colonisation and extinction and low stability. The redistribution of aphids within the crop at the local scale is a vulnerability which could be used to disrupt population development--by mediating exposure to ground-active natural enemies and by incurring a metabolic cost caused by the physiological demands to re-establish on a nearby host plant.

  8. Design and manufacturing of customised femoral stems for the Indian population using rapid manufacturing: a finite element approach.

    Science.gov (United States)

    Madhugiri, T S; Kuthe, A M; Deshmukh, T R

    2011-01-01

    Joint replacement surgeries in India primarily involve the use of conventional implants, also referred to as 'standard implants'. There has been a little awareness about the possibility of using customised implants for such surgeries. Although standard implants from various biomedical companies are easily available in the Indian market, they are expensive and rarely conform to patient's anatomy. Studies in the past have shown that there are anatomical variations in the hip joint for different ethnic backgrounds and geographical locations. This article evaluates the feasibility of using custom-manufactured hip implants and presents a comparison between the former and standard implant from stress reduction point of view. Two CAD models of femoral stems - one from standard sized hip implant available in the market and other from customised hip implant designed as per parameters from a radiograph (specific to the patient's anatomy) - are used for evaluation. Finite element analysis was carried out for a double-legged stance. The comparative study indicated lesser stresses in head and neck region of the customised femoral stems than the standard implant. The study suggests design feasibility of customised implants for the Indian population owing to reduction in stresses in the implant.

  9. Turnover in health care: the mediating effects of employee engagement.

    Science.gov (United States)

    Collini, Stevie A; Guidroz, Ashley M; Perez, Lisa M

    2015-03-01

    This study aimed to understand the interaction between interpersonal respect, diversity climate, mission fulfilment and engagement to better predict turnover in health care. Registered nurse turnover has averaged 14% and current nursing shortages are expected to spread. Few studies have studied employee engagement as a mediator between organisational context and turnover. Study participants were employees working within 185 departments across ten hospitals within a large healthcare organisation in the USA. Although a total of 5443 employees work in these departments, employee opinion survey responses were aggregated by department before being linked to turnover rates gathered from company records. Engagement fully mediated the relationship between respect and turnover and the relationship between mission fulfilment and turnover. Diversity climate was not related to turnover. Turnover in health care poses a significant threat to the mission of creating a healing environment for patients and these results demonstrate that workplace respect and connection to the mission affect turnover by decreasing engagement. The findings demonstrated that to increase engagement, and improve turnover rates in health care, it would be beneficial for organisations, and nurse management to focus on improving mission fulfilment and interpersonal relationships. © 2013 John Wiley & Sons Ltd.

  10. Sexual selection affects local extinction and turnover in bird communities

    Science.gov (United States)

    Doherty, P.F.; Sorci, G.; Royle, J. Andrew; Hines, J.E.; Nichols, J.D.; Boulinier, T.

    2003-01-01

    Predicting extinction risks has become a central goal for conservation and evolutionary biologists interested in population and community dynamics. Several factors have been put forward to explain risks of extinction, including ecological and life history characteristics of individuals. For instance, factors that affect the balance between natality and mortality can have profound effects on population persistence. Sexual selection has been identified as one such factor. Populations under strong sexual selection experience a number of costs ranging from increased predation and parasitism to enhanced sensitivity to environmental and demographic stochasticity. These findings have led to the prediction that local extinction rates should be higher for species/populations with intense sexual selection. We tested this prediction by analyzing the dynamics of natural bird communities at a continental scale over a period of 21 years (1975-1996), using relevant statistical tools. In agreement with the theoretical prediction, we found that sexual selection increased risks of local extinction (dichromatic birds had on average a 23% higher local extinction rate than monochromatic species). However, despite higher local extinction probabilities, the number of dichromatic species did not decrease over the period considered in this study. This pattern was caused by higher local turnover rates of dichromatic species, resulting in relatively stable communities for both groups of species. Our results suggest that these communities function as metacommunities, with frequent local extinctions followed by colonization. Anthropogenic factors impeding dispersal might therefore have a significant impact on the global persistence of sexually selected species.

  11. Endogenous Turnover of Cyanogenic Glycosides in Plants

    DEFF Research Database (Denmark)

    Picmanova, Martina

    with noncyanogenic compounds glaringly resembling their structures. In order to examine the spatial as well as temporal presence and abundance of the putative turnover products of CNglcs, comparative metabolic profiling using LC-MS/MS was performed in three cyanogenic crops – cassava, almond and sorghum. This work...... of the proposed catabolic route, even though the enzymes involved remain elusive. Testing of heterologously expressed and purified nitrilases and nitrilase-related enzymes from cassava and almond, including NIT4s, glutamine-dependent NAD+ synthetase (QNS) and a newly discovered nucleus-localized nitrilase...

  12. Two populations of amphibole in dacite magmas at Volcan Aucanquilcha, Chile: A case for rapid and repeated mixing of a tiered magmatic system

    Science.gov (United States)

    Klemetti, E. W.; Grunder, A. L.

    2006-12-01

    Magmatic amphibole is a ubiquitous phase in most dacitic magmas in continental arc systems. Amphibole can react quickly to changes in P, T and water content caused by processes such as underplating of new magma, degassing, ascension and mixing of magma. This allows amphibole to be a valuable and sensitive barometer, thermometer and hygrometer in silicic magmatic systems. It can be especially suitable for disentangling the potential geometry of subvolcanic systems and limiting the timescales that these processes can occur. Volcán Aucanquilcha (Chile) is a Quaternary volcano that has erupted dacite lavas (63-67 wt% SiO2) that contain two populations of amphibole during its entire 1 M.y. eruptive history. The amphibole is found as phenocrysts of hornblende and pargasite that range in size from 0.5 mm to 1 cm. The amphibole populations exhibit a variety of textures: (1) thin opacite rims; (2) thick reaction rims of pyroxene, plagioclase and opaque oxides; (3) cored" with other phases such as plagioclase, biotite and anhydride; and (4) unrimmed. Representative electron microprobe analyses of amphibole find that very few of the phenocrysts are compositionally zoned, i.e., the two populations are not pargasite cores with hornblende rims. The presence of two populations of amphibole such as those found at Aucanquilcha appears to be rare; there are documented occurrences of two amphibole populations found in lavas from continental-arc related volcanoes. Sajama, Parinacota and Porquesa in Central Andes of Chile exhibit the same two populations of amphibole phenocrysts as Aucanquilcha. Evidence from Aucanquilcha suggest that the populations of amphibole crystallized at different pressures: 0.5-2 kb and 3-6 kb. Textures of the amphibole imply that the processes that mix the amphibole occur quickly before eruption, possibly in a timescales of days. The constant presence of these amphibole in all Aucanquilcha lavas indicate that the processes that juxtapose pargasite and

  13. How did Japanese rural dwellers become rapidly healthier in the two decades following World War II?: Examining the diverse policy interventions that improved the population's health.

    Science.gov (United States)

    Yuasa, Motoyuki

    2017-01-01

    policies implemented in Japan as well as the integration of various policies and programs addressing livelihoods, economics, and education greatly improved the population's health in a relatively short time. These non-health initiatives intersected with a wide range of health determinants. Verifying these hypotheses in detail would help develop effective measures for international aid to poverty-stricken regions. It also encourages alternative ways through which Japan could overcome its present-day challenges such as a rapidly aging population with limited access to national schemes for social security.

  14. A population-based cross-sectional study of barriers to uptake of eye care services in South India: the Rapid Assessment of Visual Impairment (RAVI) project.

    Science.gov (United States)

    Marmamula, Srinivas; Khanna, Rohit C; Shekhar, Konegari; Rao, Gullapalli N

    2014-06-12

    To assess the barriers to uptake of eye care services among those with avoidable impairment in the population aged ≥40 years in the South Indian state of Andhra Pradesh. Cross-sectional study. Community setting. Of 7800 participants recruited from one urban and two rural locations using a two-stage cluster random sampling methodology, 7378 (95%) were examined. Eye examinations were conducted using a rapid assessment protocol. Visual impairment (VI) was defined as presenting visual acuity attitude and 'felt need' to improve vision, newer and much intensive awareness campaigns are needed to bring about an attitudinal/behavioural change among individuals to improve the uptake of services. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  15. Clonal turnover of MACE-carrying peach-potato aphids (Myzus persicae (Sulzer), Homoptera: Aphididae) colonizing Scotland.

    Science.gov (United States)

    Kasprowicz, L; Malloch, G; Foster, S; Pickup, J; Zhan, J; Fenton, B

    2008-04-01

    Peach-potato aphids, Myzus persicae (Sulzer), collected in Scotland in the years 1995 and 2002-2004 were characterized using four microsatellite loci and three insecticide resistance mechanisms. From 868 samples, 14 multilocus genotypes were defined (designated clones A-N). Five of these (denoted A, B, H, M and N) carried modified acetylcholinesterase (MACE) resistance, the most recent resistance mechanism to have evolved in M. persicae. The current paper shows that the continued presence of MACE aphids is due to turnover, as clones A and B were replaced in field samples by clones H, M and N in later seasons. Thus, insecticide-resistant populations in Scotland can be attributed to multiple waves of rapid clone colonisations and not to the continued presence of stable resistant clones or mutation or sexual recombination in local populations. The MACE clones carried varying levels of the other insecticide resistance mechanisms, kdr and esterase. The presence of these mechanisms could alter the clones success in the field depending on insecticide spraying (positive selection) and resistance fitness costs (negative selection).

  16. Nitrogen turnover in soil and global change.

    Science.gov (United States)

    Ollivier, Julien; Töwe, Stefanie; Bannert, Andrea; Hai, Brigitte; Kastl, Eva-Maria; Meyer, Annabel; Su, Ming Xia; Kleineidam, Kristina; Schloter, Michael

    2011-10-01

    Nitrogen management in soils has been considered as key to the sustainable use of terrestrial ecosystems and a protection of major ecosystem services. However, the microorganisms driving processes like nitrification, denitrification, N-fixation and mineralization are highly influenced by changing climatic conditions, intensification of agriculture and the application of new chemicals to a so far unknown extent. In this review, the current knowledge concerning the influence of selected scenarios of global change on the abundance, diversity and activity of microorganisms involved in nitrogen turnover, notably in agricultural and grassland soils, is summarized and linked to the corresponding processes. In this context, data are presented on nitrogen-cycling processes and the corresponding microbial key players during ecosystem development and changes in functional diversity patterns during shifts in land use. Furthermore, the impact of increased temperature, carbon dioxide and changes in precipitation regimes on microbial nitrogen turnover is discussed. Finally, some examples of the effects of pesticides and antibiotics after application to soil for selected processes of nitrogen transformation are also shown. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  17. Relationships between Bone Turnover and Energy Metabolism

    Directory of Open Access Journals (Sweden)

    Tânia A. P. Fernandes

    2017-01-01

    Full Text Available It is well established that diabetes can be detrimental to bone health, and its chronic complications have been associated with an increased risk of osteoporotic fracture. However, there is growing evidence that the skeleton plays a key role in a whole-organism approach to physiology. The hypothesis that bone may be involved in the regulation of physiological functions, such as insulin sensitivity and energy metabolism, has been suggested. Given the roles of insulin, adipokines, and osteocalcin in these pathways, the need for a more integrative conceptual approach to physiology is emphasized. Recent findings suggest that bone plays an important role in regulating intermediary metabolism, being possibly both a target of diabetic complications and a potential pathophysiologic factor in the disease itself. Understanding the relationships between bone turnover and glucose metabolism is important in order to develop treatments that might reestablish energy metabolism and bone health. This review describes new insights relating bone turnover and energy metabolism that have been reported in the literature.

  18. Explaining turnover intention in Korean public community hospitals: occupational differences.

    Science.gov (United States)

    Hwang, Jee-In; Chang, Hyejung

    2008-01-01

    Personnel in public hospitals had relatively low job satisfaction despite of tenure employment. High turnover rates degrade hospital image and incur additional costs related to recruitment and training. The purposes of this study were to describe the occupational differences and to identify factors affecting turnover intention among public hospital personnel. A questionnaire survey was conducted as part of Administrative Services Quality Evaluation Program by Seoul metropolitan municipality from 1 November to 1 December in 2003. The subjects were 1251 entire hospital personnel in four hospitals. The questionnaire was designed to measure job satisfaction, organizational commitment, turnover intention, and demographic characteristics. Logistic regression analysis was performed to determine factors influencing turnover intention. There were significant differences in job satisfaction, organizational commitment, and turnover intention according to the occupations. The turnover intention rates were highest among physicians, followed by paramedicals and nursing staffs and then administrators. The significant factors affecting turnover intention were involvement and loyalty among physicians, hospital type, satisfaction with systems and loyalty among nursing staffs, satisfaction with relationship and loyalty among administrators, and loyalty among paramedicals. There were different moderators that influence turnover intentions of hospital personnel. Loyalty had the most important effect upon turnover intention in all occupations. 2007 John Wiley & Sons, Ltd

  19. Cultural turnover among Galápagos sperm whales.

    Science.gov (United States)

    Cantor, Mauricio; Whitehead, Hal; Gero, Shane; Rendell, Luke

    2016-10-01

    While populations may wax and wane, it is rare for an entire population to be replaced by a completely different set of individuals. We document the large-scale relocation of cultural groups of sperm whale off the Galápagos Islands, in which two sympatric vocal clans were entirely replaced by two different ones. Between 1985 and 1999, whales from two clans (called Regular and Plus-One) defined by cultural dialects in coda vocalizations were repeatedly photo-identified off Galápagos. Their occurrence in the area declined through the 1990s; by 2000, none remained. We reassessed Galápagos sperm whales in 2013-2014, identifying 463 new females. However, re-sighting rates were low, with no matches with the Galápagos 1985-1999 population, suggesting an eastward shift to coastal areas. Their vocal repertoires matched those of two other clans (called Short and Four-Plus) found across the Pacific but previously rare or absent around Galápagos. The mechanisms behind this cultural turnover may include large-scale environmental regime shifts favouring clan-specific foraging strategies, and a response to heavy whaling in the region involving redistribution of surviving whales into high-quality habitats. The fall and rise of sperm whale cultures off Galápagos reflect the structuring of the Pacific population into large, enduring clans with dynamic ranges. Long-lasting clan membership illustrates how culture can be bound up in the structure and dynamics of animal populations and so how tracking cultural traits can reveal large-scale population shifts.

  20. Signal-dependent turnover of the bacterial flagellar switch protein FliM.

    Science.gov (United States)

    Delalez, Nicolas J; Wadhams, George H; Rosser, Gabriel; Xue, Quan; Brown, Mostyn T; Dobbie, Ian M; Berry, Richard M; Leake, Mark C; Armitage, Judith P

    2010-06-22

    Most biological processes are performed by multiprotein complexes. Traditionally described as static entities, evidence is now emerging that their components can be highly dynamic, exchanging constantly with cellular pools. The bacterial flagellar motor contains approximately 13 different proteins and provides an ideal system to study functional molecular complexes. It is powered by transmembrane ion flux through a ring of stator complexes that push on a central rotor. The Escherichia coli motor switches direction stochastically in response to binding of the response regulator CheY to the rotor switch component FliM. Much is known of the static motor structure, but we are just beginning to understand the dynamics of its individual components. Here we measure the stoichiometry and turnover of FliM in functioning flagellar motors, by using high-resolution fluorescence microscopy of E. coli expressing genomically encoded YPet derivatives of FliM at physiological levels. We show that the approximately 30 FliM molecules per motor exist in two discrete populations, one tightly associated with the motor and the other undergoing stochastic turnover. This turnover of FliM molecules depends on the presence of active CheY, suggesting a potential role in the process of motor switching. In many ways the bacterial flagellar motor is as an archetype macromolecular assembly, and our results may have further implications for the functional relevance of protein turnover in other large molecular complexes.

  1. Signal-dependent turnover of the bacterial flagellar switch protein FliM

    Science.gov (United States)

    Delalez, Nicolas J.; Wadhams, George H.; Rosser, Gabriel; Xue, Quan; Brown, Mostyn T.; Dobbie, Ian M.; Berry, Richard M.; Leake, Mark C.; Armitage, Judith P.

    2010-01-01

    Most biological processes are performed by multiprotein complexes. Traditionally described as static entities, evidence is now emerging that their components can be highly dynamic, exchanging constantly with cellular pools. The bacterial flagellar motor contains ∼13 different proteins and provides an ideal system to study functional molecular complexes. It is powered by transmembrane ion flux through a ring of stator complexes that push on a central rotor. The Escherichia coli motor switches direction stochastically in response to binding of the response regulator CheY to the rotor switch component FliM. Much is known of the static motor structure, but we are just beginning to understand the dynamics of its individual components. Here we measure the stoichiometry and turnover of FliM in functioning flagellar motors, by using high-resolution fluorescence microscopy of E. coli expressing genomically encoded YPet derivatives of FliM at physiological levels. We show that the ∼30 FliM molecules per motor exist in two discrete populations, one tightly associated with the motor and the other undergoing stochastic turnover. This turnover of FliM molecules depends on the presence of active CheY, suggesting a potential role in the process of motor switching. In many ways the bacterial flagellar motor is as an archetype macromolecular assembly, and our results may have further implications for the functional relevance of protein turnover in other large molecular complexes. PMID:20498085

  2. Rapid and accurate species and genomic species identification and exhaustive population diversity assessment of Agrobacterium spp. using recA-based PCR.

    Science.gov (United States)

    Shams, M; Vial, L; Chapulliot, D; Nesme, X; Lavire, C

    2013-07-01

    Agrobacteria are common soil bacteria that interact with plants as commensals, plant growth promoting rhizobacteria or alternatively as pathogens. Indigenous agrobacterial populations are composites, generally with several species and/or genomic species and several strains per species. We thus developed a recA-based PCR approach to accurately identify and specifically detect agrobacteria at various taxonomic levels. Specific primers were designed for all species and/or genomic species of Agrobacterium presently known, including 11 genomic species of the Agrobacterium tumefaciens complex (G1-G9, G13 and G14, among which only G2, G4, G8 and G14 still received a Latin epithet: pusense, radiobacter, fabrum and nepotum, respectively), A. larrymoorei, A. rubi, R. skierniewicense, A. sp. 1650, and A. vitis, and for the close relative Allorhizobium undicola. Specific primers were also designed for superior taxa, Agrobacterium spp. and Rhizobiaceace. Primer specificities were assessed with target and non-target pure culture DNAs as well as with DNAs extracted from composite agrobacterial communities. In addition, we showed that the amplicon cloning-sequencing approach used with Agrobacterium-specific or Rhizobiaceae-specific primers is a way to assess the agrobacterial diversity of an indigenous agrobacterial population. Hence, the agrobacterium-specific primers designed in the present study enabled the first accurate and rapid identification of all species and/or genomic species of Agrobacterium, as well as their direct detection in environmental samples. Copyright © 2013 Elsevier GmbH. All rights reserved.

  3. Multiplex Minisequencing of the HBB Gene: A Rapid Strategy to Confirm the Most Frequent β-Thalassemia Mutations in the Tunisian Population.

    Science.gov (United States)

    Ben Charfeddine, Ilhem; Ben Lazreg, Taheni; M'sakni, Ahlem; Amara, Abdelbasset; Mlika, Adnène; Chaïeb, Anouar; Hlel, Khalid; Zouari, Noura; Zbidi, Faïza; Bouguila, Jihène; Soyah, Najla; Ayedi, Abdelkarim; Ben Hamouda, Hechmi; Abroug, Saoussen; Boughamoura, Lamia; Saad, Ali; Gribaa, Moez

    2015-01-01

    The β hemoglobinopathies [β-thalassemia (β-thal) and structural hemoglobin (Hb) variants such as Hb S (HBB: c.20A > T) and Hb E (HBB: c.79G > A)] are among the most common inherited diseases worldwide. In Tunisia, due to the high prevalence of consanguineous marriages, the recurrent risk of this disease is high. The average prevalence of hemoglobinopathies is 4.48%, reaching 12.50% in some focus regions. The molecular investigations on thalassemia contributed to establishing the spectrum of mutations in the Tunisian population. The total number of HBB gene mutations identified was 24. The two most frequent mutations, codon 39 (C > T) (HBB: c.118C > T) and IVS-I-110 (G > A) (HBB: c.93-21G > A) accounted for 70.0% of the total encountered β-thal cases. These two mutations together with IVS-I-2 (T > G) (HBB: c.92 + 2T > G) and the Hb S variant account for more than 90.0% of all HBB genetic variants in Tunisia. Thus, developing rapid, inexpensive and reliable mutation-specific molecular diagnostic assays targeting our Tunisian populations is our aim to facilitate routine detection of hemoglobinopathies. In this report, we describe the successful application of the multiplex minisequencing assay as an alternative strategy for genetic diagnosis of HBB gene disorders in Tunisia.

  4. Global Proteome Turnover Analyses of the Yeasts S. cerevisiae and S. pombe

    Directory of Open Access Journals (Sweden)

    Romain Christiano

    2014-12-01

    Full Text Available How cells maintain specific levels of each protein and whether that control is evolutionarily conserved are key questions. Here, we report proteome-wide steady-state protein turnover rate measurements for the evolutionarily distant but ecologically similar yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe. We find that the half-life of most proteins is much longer than currently thought and determined to a large degree by protein synthesis and dilution due to cell division. However, we detect a significant subset of proteins (∼15% in both yeasts that are turned over rapidly. In addition, the relative abundances of orthologous proteins between the two yeasts are highly conserved across the 400 million years of evolution. In contrast, their respective turnover rates differ considerably. Our data provide a high-confidence resource for studying protein degradation in common yeast model systems.

  5. Turnover rates in microorganisms by laser ablation electrospray ionization mass spectrometry and pulse-chase analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stopka, Sylwia A.; Mansour, Tarek R.; Shrestha, Bindesh [Department of Chemistry, W.M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, DC 20052 (United States); Maréchal, Éric; Falconet, Denis [Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, CEA-CNRS-INRA-Univ. Grenoble Alpes, Grenoble (France); Vertes, Akos, E-mail: vertes@gwu.edu [Department of Chemistry, W.M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, DC 20052 (United States)

    2016-01-01

    Biochemical processes rely on elaborate networks containing thousands of compounds participating in thousands of reaction. Rapid turnover of diverse metabolites and lipids in an organism is an essential part of homeostasis. It affects energy production and storage, two important processes utilized in bioengineering. Conventional approaches to simultaneously quantify a large number of turnover rates in biological systems are currently not feasible. Here we show that pulse-chase analysis followed by laser ablation electrospray ionization mass spectrometry (LAESI-MS) enable the simultaneous and rapid determination of metabolic turnover rates. The incorporation of ion mobility separation (IMS) allowed an additional dimension of analysis, i.e., the detection and identification of isotopologs based on their collision cross sections. We demonstrated these capabilities by determining metabolite, lipid, and peptide turnover in the photosynthetic green algae, Chlamydomonas reinhardtii, in the presence of {sup 15}N-labeled ammonium chloride as the main nitrogen source. Following the reversal of isotope patterns in the chase phase by LAESI-IMS-MS revealed the turnover rates and half-lives for biochemical species with a wide range of natural concentrations, e.g., chlorophyll metabolites, lipids, and peptides. For example, the half-lives of lyso-DGTS(16:0) and DGTS(18:3/16:0), t{sub 1/2} = 43.6 ± 4.5 h and 47.6 ± 2.2 h, respectively, provided insight into lipid synthesis and degradation in this organism. Within the same experiment, half-lives for chlorophyll a, t{sub 1/2} = 24.1 ± 2.2 h, and a 2.8 kDa peptide, t{sub 1/2} = 10.4 ± 3.6 h, were also determined. - Highlights: • High-throughput pulse-chase analysis using direct sampling of biological cells. • Ion mobility separation for the elucidation of isotopologs. • Identification of isotopologs in difference heat plots of DT vs. m/z. • Simultaneous determination of turnover rates for lipids and

  6. An ultra-high density bin-map for rapid QTL mapping for tassel and ear architecture in a large F₂ maize population.

    Science.gov (United States)

    Chen, Zongliang; Wang, Baobao; Dong, Xiaomei; Liu, Han; Ren, Longhui; Chen, Jian; Hauck, Andrew; Song, Weibin; Lai, Jinsheng

    2014-06-04

    Understanding genetic control of tassel and ear architecture in maize (Zea mays L. ssp. mays) is important due to their relationship with grain yield. High resolution QTL mapping is critical for understanding the underlying molecular basis of phenotypic variation. Advanced populations, such as recombinant inbred lines, have been broadly adopted for QTL mapping; however, construction of large advanced generation crop populations is time-consuming and costly. The rapidly declining cost of genotyping due to recent advances in next-generation sequencing technologies has generated new possibilities for QTL mapping using large early generation populations. A set of 708 F2 progeny derived from inbreds Chang7-2 and 787 were generated and genotyped by whole genome low-coverage genotyping-by-sequencing method (average 0.04×). A genetic map containing 6,533 bin-markers was constructed based on the parental SNPs and a sliding-window method, spanning a total genetic distance of 1,396 cM. The high quality and accuracy of this map was validated by the identification of two well-studied genes, r1, a qualitative trait locus for color of silk (chromosome 10) and ba1 for tassel branch number (chromosome 3). Three traits of tassel and ear architecture were evaluated in this population, a total of 10 QTL were detected using a permutation-based-significance threshold, seven of which overlapped with reported QTL. Three genes (GRMZM2G316366, GRMZM2G492156 and GRMZM5G805008) encoding MADS-box domain proteins and a BTB/POZ domain protein were located in the small intervals of qTBN5 and qTBN7 (~800 Kb and 1.6 Mb in length, respectively) and may be involved in patterning of tassel architecture. The small physical intervals of most QTL indicate high-resolution mapping is obtainable with this method. We constructed an ultra-high-dentisy linkage map for the large early generation population in maize. Our study provides an efficient approach for fast detection of quantitative loci responsible

  7. Microbial regulation of pesticide degradation coupled to carbon turnover in the detritusphere

    OpenAIRE

    Pagel, Holger

    2015-01-01

    Many soil functions, such as nutrient cycling or pesticide degradation, are controlled by microorganisms. Dynamics of microbial populations and biogeochemical cycling in soil are largely determined by the availability of carbon (C). The detritusphere is a microbial “hot spot” of C turnover. It is characterized by a concentration gradient of C from litter (high) into the adjacent soil (lower). Therefore, this microhabitat is very well suited to investigate the influence of C availability on mi...

  8. Bone mass and turnover in fibromyalgia

    DEFF Research Database (Denmark)

    Jacobsen, Søren; Gam, A; Egsmose, C

    1993-01-01

    Physical inactivity accelerates bone loss. Since patients with fibromyalgia are relatively physically inactive, bone mass and markers of bone metabolism were determined in 12 premenopausal women with fibromyalgia and in healthy age matched female control subjects. No differences were found...... in lumbar bone mineral density, femoral neck bone mineral density, serum levels of alkaline phosphatase, osteocalcin, ionized calcium and phosphate. The urinary excretion of both hydroxyproline and calcium relative to urinary creatinine excretion was significantly higher in patients with fibromyalgia, p = 0.......01. This was linked to lower urinary creatinine excretion (p = 0.02) probably reflecting lower physical activity in the patients with fibromyalgia. We conclude that bone mass and turnover are generally not affected in premenopausal women with fibromyalgia....

  9. Organizational commitment and turnover intentions in humanitarian organizations

    NARCIS (Netherlands)

    Wijnmalen, Julia; Heyse, Liesbet; Voordijk, Hans

    2016-01-01

    Unwanted staff turnover is a prominent HRM problem in humanitarian organisations. In the profit sector, HRM tools such as pay, benefits, socialisation and training have proven to be effective in increasing organisational commitment and decreasing staff turnover. This study explores whether such

  10. How Multiple Interventions Influenced Employee Turnover: A Case Study.

    Science.gov (United States)

    Hatcher, Timothy

    1999-01-01

    A 3-year study of 46 textile industry workers identified causes of employee turnover (supervision, training, organizational communication) using performance analysis. A study of multiple interventions based on the analysis resulted in changes in orientation procedures, organizational leadership, and climate, reducing turnover by 24%. (SK)

  11. Survey of pay satisfaction, job satisfaction and employee turnover in ...

    African Journals Online (AJOL)

    Survey of pay satisfaction, job satisfaction and employee turnover in selected business organisations in Lagos, Nigeria. ... Global Journal of Social Sciences ... The study was an attempt at investigating the relatedness of pay satisfaction, job satisfaction and employee turnover in business organizations in Lagos Nigeria.

  12. Glucose turnover during pregnancy in anaesthetized post-absorptive rats

    OpenAIRE

    Leturque, Armelle; Gilbert, Marc; Girard, Jean

    1981-01-01

    During pregnancy the decline in blood [glucose] does not result from the increased distribution space of glucose. The absolute rate of glucose turnover increases in late pregnancy in parallel with the rise in the mass of the conceptus. Nevertheless, glucose turnover per kg body wt. is not increased in late pregnancy, since the lower blood [glucose] decreases glucose utilization by maternal tissues.

  13. Performance and turnover intentions: a social exchange perspective

    NARCIS (Netherlands)

    Biron, M.; Boon, C.

    2013-01-01

    Purpose - Prior research has yielded mixed results regarding the relationship between performance and turnover intentions. Drawing from social exchange theory, the purpose of this paper is to propose that the performance-turnover intentions association may be contingent upon individuals' exchange

  14. Health workforce acquisition, retention and turnover in southwest ...

    African Journals Online (AJOL)

    Background: Skill mix of health professionals, staff acquisition and turnover rate are among the major challenges for the delivery of quality health care. This study assessed the health workforce acquisition, retention, turnover rate and their intention to leave. Methods: A cross-sectional survey with quantitative and qualitative ...

  15. Managing teacher turnover | Xaba | South African Journal of Education

    African Journals Online (AJOL)

    Concerns about educator turnover and attrition are reported widely as a global phenomenon. Turnover translates, amongst other things, into shortages in educator supply, costs in recruitment, training and mentoring, poor learner performance due to disruption of planning programmes and continuity, as well as overcrowded ...

  16. Below the Surface of Special Education Administrator Turnover

    Science.gov (United States)

    Meeks, Amy

    2016-01-01

    The field of special education administration has experienced a shortage of high quality special education leadership candidates for several decades. If school districts are to effectively address the turnover of educational leaders, they must know what is happening that affects turnover of their leadership team. The intent of this study was to…

  17. The Link between Training Satisfaction, Work Engagement and Turnover Intention

    Science.gov (United States)

    Memon, Mumtaz Ali; Salleh, Rohani; Baharom, Mohamed Noor Rosli

    2016-01-01

    Purpose: The purpose of this paper is to examine the casual relationship between training satisfaction, work engagement (WE) and turnover intention and the mediating role of WE between training satisfaction and turnover intention. Design/methodology/approach: Data were collected from 409 oil and gas professionals using an email survey…

  18. Regulatory mechanisms of skeletal muscle protein turnover during exercise

    DEFF Research Database (Denmark)

    Rose, Adam John; Richter, Erik

    2009-01-01

    Skeletal muscle protein turnover is a relatively slow metabolic process that is altered by various physiological stimuli such as feeding/fasting and exercise. During exercise, catabolism of amino acids contributes very little to ATP turnover in working muscle. With regards to protein turnover......, there is now consistent data from tracer studies in rodents and humans showing that global protein synthesis is blunted in working skeletal muscle. Whether there is altered skeletal muscle protein breakdown during exercise remains unclear. The blunting of protein synthesis is believed to be mediated...... downstream of changes in intracellular Ca(2+) and energy turnover. In particular, a signaling cascade involving Ca(2+)-calmodulin-eEF2 kinase-eEF2 is implicated. The possible functional significance of altered protein turnover in working skeletal muscle during exercise is discussed. Further work...

  19. Pitfalls in quantifying species turnover: the residency effect

    Directory of Open Access Journals (Sweden)

    Kevin Chase Burns

    2014-03-01

    Full Text Available The composition of ecological communities changes continuously through time and space. Understanding this turnover in species composition is a central goal in biogeography, but quantifying species turnover can be problematic. Here, I describe an underappreciated source of bias in quantifying species turnover, namely ‘the residency effect’, which occurs when the contiguous distributions of species across sampling domains are small relative to census intervals. I present the results of a simulation model that illustrates the problem theoretically and then I demonstrate the problem empirically using a long-term dataset of plant species turnover on islands. Results from both exercises indicate that empirical estimates of species turnover may be susceptible to significant observer bias, which may potentially cloud a better understanding of how the composition of ecological communities changes through time.

  20. The Relationship between Job Satisfaction and Intent to Turnover among Software Engineers in the Information Technology Industry

    Science.gov (United States)

    Agada, Chuks N.

    2013-01-01

    The focus of this study was to examine the relationship between job satisfaction and intent to turnover among software engineers in the information technology (IT) industry. The population that was analyzed in this study was software engineers in the IT industry to determine whether there is a relationship between job satisfaction and intent to…

  1. Highly visible street-based HIV rapid testing: is it an attractive option for a previously untested population? A cross-sectional study.

    Science.gov (United States)

    Fernández-Balbuena, Sonia; de la Fuente, Luis; Hoyos, Juan; Rosales-Statkus, M Elena; Barrio, Gregorio; Belza, María-José

    2014-03-01

    Given the shortage of community-based HIV testing initiatives in resource-rich countries not targeting most-at-risk populations, we aimed to evaluate whether a highly visible mobile programme promoting and offering rapid HIV testing in the street can attract persons at risk for infection who have never been tested. Between 2008 and 2011, the programme served 7552 persons in various Spanish cities who answered a brief questionnaire while awaiting their results. The factors associated with being tested for the first time were analysed using two logistic regression models, one for men who have sex with men (MSM) and the other for only heterosexual men (MSW) and women. 3517 participants (47%) were first-time testers (24% of MSM, 56% of MSW and 60% of women). Among them, 22 undiagnosed HIV infections were detected with a global prevalence of 0.6% and 3.1% in MSM. Undergoing a first HIV test was independently associated with age gay community. Among those tested for the first time, 22% had never thought of being tested and 62% decided to be tested when they passed by and noticed the programme, regardless of their previous intentions. This community programme attracted a substantial number of persons previously untested and particularly hard to reach, such as those with low education and MSM who were least involved in the gay community. Programme visibility was a decisive factor for almost two of every three persons who had never been tested.

  2. Alcohol tax policy and related mortality. An age-period-cohort analysis of a rapidly developed Chinese population, 1981-2010.

    Science.gov (United States)

    Chung, Roger Y; Kim, Jean H; Yip, Benjamin H; Wong, Samuel Y S; Wong, Martin C S; Chung, Vincent C H; Griffiths, Sian M

    2014-01-01

    To delineate the temporal dynamics between alcohol tax policy changes and related health outcomes, this study examined the age, period and cohort effects on alcohol-related mortality in relation to changes in government alcohol policies. We used the age-period-cohort modeling to analyze retrospective mortality data over 30 years from 1981 to 2010 in a rapidly developed Chinese population, Hong Kong. Alcohol-related mortality from 1) chronic causes, 2) acute causes, 3) all (chronic+acute) causes and 4) causes 100% attributable to alcohol, as defined according to the Alcohol-Related Disease Impact (ARDI) criteria developed by the US Centers for Disease Control and Prevention, were examined. The findings illustrated the possible effects of alcohol policy changes on adult alcohol-related mortality. The age-standardized mortality trends were generally in decline, with fluctuations that coincided with the timing of the alcohol policy changes. The age-period-cohort analyses demonstrated possible temporal dynamics between alcohol policy changes and alcohol-related mortality through the period effects, and also generational impact of alcohol policy changes through the cohort effects. Based on the illustrated association between the dramatic increase of alcohol imports in the mid-1980s and the increased alcohol-related mortality risk of the generations coming of age of majority at that time, attention should be paid to generations coming of drinking age during the 2007-2008 duty reduction.

  3. Turnover of microbial groups and cell components in soil: 13C analysis of cellular biomarkers

    Science.gov (United States)

    Gunina, Anna; Dippold, Michaela; Glaser, Bruno; Kuzyakov, Yakov

    2017-01-01

    Microorganisms regulate the carbon (C) cycle in soil, controlling the utilization and recycling of organic substances. To reveal the contribution of particular microbial groups to C utilization and turnover within the microbial cells, the fate of 13C-labelled glucose was studied under field conditions. Glucose-derived 13C was traced in cytosol, amino sugars and phospholipid fatty acid (PLFA) pools at intervals of 3, 10 and 50 days after glucose addition into the soil. 13C enrichment in PLFAs ( ˜ 1.5 % of PLFA C at day 3) was an order of magnitude greater than in cytosol, showing the importance of cell membranes for initial C utilization. The 13C enrichment in amino sugars of living microorganisms at day 3 accounted for 0.57 % of total C pool; as a result, we infer that the replacement of C in cell wall components is 3 times slower than that of cell membranes. The C turnover time in the cytosol (150 days) was 3 times longer than in PLFAs (47 days). Consequently, even though the cytosol pool has the fastest processing rates compared to other cellular compartments, intensive recycling of components here leads to a long C turnover time. Both PLFA and amino-sugar profiles indicated that bacteria dominated in glucose utilization. 13C enrichment decreased with time for bacterial cell membrane components, but it remained constant or even increased for filamentous microorganisms. 13C enrichment of muramic acid was the 3.5 times greater than for galactosamine, showing a more rapid turnover of bacterial cell wall components compared to fungal. Thus, bacteria utilize a greater proportion of low-molecular-weight organic substances, whereas filamentous microorganisms are responsible for further C transformations. Thus, tracing 13C in cellular compounds with contrasting turnover rates elucidated the role of microbial groups and their cellular compartments in C utilization and recycling in soil. The results also reflect that microbial C turnover is not restricted to the death or

  4. Active turnover regulates pattern formation and stress transmission in disordered acto-myosin networks

    Science.gov (United States)

    McCall, Patrick; Stam, Samantha; Kovar, David; Gardel, Margaret

    The shape and mechanics of animal cells are controlled by a dynamic, thin network of semiflexible actin filaments and myosin-II motor proteins called the actomyosin cortex. Motor-generated stresses in the cortex drive changes in cell shape during cell division and morphogenesis, while dynamic turnover of actin filaments dissipates stress. The relative effects that force generation, force dissipation, and disassembly and reassembly of material have on motion in these networks are unknown. We find that cross-linked actin networks in vitro contract under myosin-generated stresses, resulting in partial filament disassembly, the formation of asters, and clustering of myosin motors. We observe a rapid restoration of uniform polymer density in the presence of the assembly factors which catalyze network turnover through elongation of severed actin filaments. When severing is accelerated further by the addition of a severing protein, network contraction and motor clustering are dramatically suppressed. We test the relative effects of material regeneration and force transmission using image analysis, and conclude that the dominant mechanism for this effect is relatively short-lived stresses that do not propagate over considerable distance or push network deformation into the nonlinear contractile regime we have previously characterized. Our results present a framework to understand cytoskeletal active matter that are influenced by a complex interplay between stress generation, network reorganization, and polymer turnover.

  5. Storage and turnover of organic matter in soil

    Energy Technology Data Exchange (ETDEWEB)

    Torn, M.S.; Swanston, C.W.; Castanha, C.; Trumbore, S.E.

    2008-07-15

    Historically, attention on soil organic matter (SOM) has focused on the central role that it plays in ecosystem fertility and soil properties, but in the past two decades the role of soil organic carbon in moderating atmospheric CO{sub 2} concentrations has emerged as a critical research area. This chapter will focus on the storage and turnover of natural organic matter in soil (SOM), in the context of the global carbon cycle. Organic matter in soils is the largest carbon reservoir in rapid exchange with atmospheric CO{sub 2}, and is thus important as a potential source and sink of greenhouse gases over time scales of human concern (Fischlin and Gyalistras 1997). SOM is also an important human resource under active management in agricultural and range lands worldwide. Questions driving present research on the soil C cycle include: Are soils now acting as a net source or sink of carbon to the atmosphere? What role will soils play as a natural modulator or amplifier of climatic warming? How is C stabilized and sequestered, and what are effective management techniques to foster these processes? Answering these questions will require a mechanistic understanding of how and where C is stored in soils. The quantity and composition of organic matter in soil reflect the long-term balance between plant carbon inputs and microbial decomposition, as well as other loss processes such as fire, erosion, and leaching. The processes driving soil carbon storage and turnover are complex and involve influences at molecular to global scales. Moreover, the relative importance of these processes varies according to the temporal and spatial scales being considered; a process that is important at the regional scale may not be critical at the pedon scale. At the regional scale, SOM cycling is influenced by factors such as climate and parent material, which affect plant productivity and soil development. More locally, factors such as plant tissue quality and soil mineralogy affect

  6. Exploring Relationships Among Occupational Safety, Job Turnover, and Age Among Home Care Aides in Maine.

    Science.gov (United States)

    Butler, Sandra S

    2017-01-01

    As the U.S. population ages, the number of people needing personal assistance in the home care setting is increasing dramatically. Personal care aides and home health workers are currently adding more jobs to the economy than any other single occupation. Home health workers face physically and emotionally challenging, and at times unsafe, work conditions, with turnover rates ranging from 44 percent to 65 percent annually. As part of a mixed-method, longitudinal study in Maine examining turnover, interviews with 252 home care aides were analyzed thematically. Responses to interview questions regarding the job's impact on health and safety, the adequacy of training, and the level of agency responsiveness were examined. Emergent themes, indicating some contradictory perspectives on workplace safety, quality of training, and agency support, were compared across three variables: job termination, occupational injury, and age. Implications for increasing occupational safety and job retention are discussed.

  7. Turnover intention among intensive care unit nurses in Alexandria, Egypt.

    Science.gov (United States)

    Mosallam, Rasha; Hamidi, Samer; Elrefaay, Manal

    2015-06-01

    Given the difficulty in recruiting new nurses, it is imperative to retain those already in the profession. This cross-sectional study explored the relationship of demographic and work-related factors, burnout, conflict management and relationship between nurses and physicians on turnover intentions among ICU nurses in eight major hospitals in Alexandria, Egypt. Data on burnout, conflict management, nurse-physician communication, and turnover intention were collected by surveying 100 nurses in eight hospitals in Alexandria governorate. All nurses at the ICU of selected hospitals were approached (n=100) and a 47-item Likert scale questionnaire was administered to explore the factors affecting the turnover intention of ICU nurses in Alexandria. ICU nurses exhibited a mean score for turnover intention of 3.23 (mean score percentage 65.0%). There was a moderately positive statistically significant correlation between turnover intention and emotional exhaustion (r=0.29, P<0.05), nurse-physician communication (r=0.25, P<0.05), and age (r=0.21, P<0.05). The predicting factors for turnover intention were emotional exhaustion and age. Nurses turnover intention at the ICU of the selected hospitals is high and is significantly associated with nurses' emotional exhaustion, poor nurse-physician communication, and nurses age.

  8. Short organic carbon turnover time and narrow 14C age spectra in early Holocene wetland paleosols

    Science.gov (United States)

    Vetter, Lael; Rosenheim, Brad E.; Fernandez, Alvaro; Törnqvist, Torbjörn E.

    2017-01-01

    Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) 14C analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, USA. We find 14C age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of 14C measurements, despite different sources of carbon with likely disparate ages. Such age spectra have not previously been observed in the sedimentary record. Here they indicate vigorous soil carbon turnover prior to burial, which homogenized 14C ages within SOM across the entire thermochemical spectrum. The weighted bulk 14C ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate 14C ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (≪300 years) of carbon in these soils relative to input of allochthonous carbon, indicating that the 14C age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat 14C ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea level rise.

  9. Employee turnover and productivity among small business entities in Nigeria

    Directory of Open Access Journals (Sweden)

    John N. N. Ugoani

    2016-12-01

    Full Text Available This study was designed to evaluate the problems of employee turnover on productivity among small business entities in Nigeria, and recommend remedial actions. Employee turnover is the separation of employees from employers and replacement with other employees. Productive manpower is a critical element for the economic survival of any small business entity. The survey research design was used for the study. The sample comprised of 320 respondents. Data generated were analyzed by using descriptive, and Z-test statistical techniques. It was found that employee turnover adversely affects productivity in small business entities.

  10. Higher Dissatisfaction Higher Turnover in the Hospitality Industry

    OpenAIRE

    Ahmad Rasmi AlBattat; Ahmad Puad Mat Som; Abdullah Saleh Helalat

    2014-01-01

    Turnover crisis reducing has been highlighted as a remarkable research theme in the hospitality industry. Regardless of the significant number of studies on employee turnover, it remains a vague issue and requires further research, It is well known that the service industry is highly dependent on the “human factor” which has become a major part of the hospitality product. The aim of this study is to give a clearer idea of enhancing employment factors to reduce the turnover crisis, Mobley`s mo...

  11. Sildenafil Stimulates Aqueous Humor Turnover in Rabbits

    Science.gov (United States)

    Alvarez, Lawrence J.; Zamudio, Aldo C.; Candia, Oscar A.

    2013-01-01

    Sildenafil citrate increases ocular blood flow and accelerates the rate of anterior chamber refilling after paracentesis. The latter effect could have resulted from a reduction in outflow facility or from an increase in aqueous humor (AH) production. In this study, we used scanning ocular fluorophotometry to examine the effects of sildenafil on AH turnover, and thus, AH production in eyes of live normal rabbits. For this, the rate of aqueous humor flow (AHF) was quantified with a commercially available fluorophotometer that measured the rate of fluorescein clearance from the anterior segment, which predominantly occurs via the trabecular meshwork. After ≈ 2 hrs of control scans to determine the baseline rate of AHF, the rabbits were fed 33 mg of sildenafil and allowed ≈ 45 min for the drug to enter the systemic circulation. Thereafter, fluorescence scans were retaken for an additional 90–120 min. Sildenafil ingestion increased AHF by about 36%, from 2.31 μL/min to 3.14 μL/min (PViagra, Revatio), stimulates AHF in rabbits. Our results seem consistent with reports indicating that the drug dilates intraocular arteries and augments intraocular vascular flow. These physiological responses to the agent apparently led to increased fluid entry into the anterior chamber. As such, the drug might have utility in patients with ocular hypotony resulting from insufficient AH formation. PMID:23562660

  12. Self-reported HIV-positive status but subsequent HIV-negative test result using rapid diagnostic testing algorithms among seven sub-Saharan African military populations.

    Directory of Open Access Journals (Sweden)

    Judith Harbertson

    Full Text Available HIV rapid diagnostic tests (RDTs combined in an algorithm are the current standard for HIV diagnosis in many sub-Saharan African countries, and extensive laboratory testing has confirmed HIV RDTs have excellent sensitivity and specificity. However, false-positive RDT algorithm results have been reported due to a variety of factors, such as suboptimal quality assurance procedures and inaccurate interpretation of results. We conducted HIV serosurveys in seven sub-Saharan African military populations and recorded the frequency of personnel self-reporting HIV positivity, but subsequently testing HIV-negative during the serosurvey. The frequency of individuals who reported they were HIV-positive but subsequently tested HIV-negative using RDT algorithms ranged from 3.3 to 91.1%, suggesting significant rates of prior false-positive HIV RDT algorithm results, which should be confirmed using biological testing across time in future studies. Simple measures could substantially reduce false-positive results, such as greater adherence to quality assurance guidelines and prevalence-specific HIV testing algorithms as described in the World Health Organization's HIV testing guidelines. Other measures to improve RDT algorithm specificity include classifying individuals with weakly positive test lines as HIV indeterminate and retesting. While expansion of HIV testing in resource-limited countries is critical to identifying HIV-infected individuals for appropriate care and treatment, careful attention to potential causes of false HIV-positive results are needed to prevent the significant medical, psychological, and fiscal costs resulting from individuals receiving a false-positive HIV diagnosis.

  13. Self-reported HIV-positive status but subsequent HIV-negative test result using rapid diagnostic testing algorithms among seven sub-Saharan African military populations.

    Science.gov (United States)

    Harbertson, Judith; Hale, Braden R; Tran, Bonnie R; Thomas, Anne G; Grillo, Michael P; Jacobs, Marni B; McAnany, Jennifer; Shaffer, Richard A

    2017-01-01

    HIV rapid diagnostic tests (RDTs) combined in an algorithm are the current standard for HIV diagnosis in many sub-Saharan African countries, and extensive laboratory testing has confirmed HIV RDTs have excellent sensitivity and specificity. However, false-positive RDT algorithm results have been reported due to a variety of factors, such as suboptimal quality assurance procedures and inaccurate interpretation of results. We conducted HIV serosurveys in seven sub-Saharan African military populations and recorded the frequency of personnel self-reporting HIV positivity, but subsequently testing HIV-negative during the serosurvey. The frequency of individuals who reported they were HIV-positive but subsequently tested HIV-negative using RDT algorithms ranged from 3.3 to 91.1%, suggesting significant rates of prior false-positive HIV RDT algorithm results, which should be confirmed using biological testing across time in future studies. Simple measures could substantially reduce false-positive results, such as greater adherence to quality assurance guidelines and prevalence-specific HIV testing algorithms as described in the World Health Organization's HIV testing guidelines. Other measures to improve RDT algorithm specificity include classifying individuals with weakly positive test lines as HIV indeterminate and retesting. While expansion of HIV testing in resource-limited countries is critical to identifying HIV-infected individuals for appropriate care and treatment, careful attention to potential causes of false HIV-positive results are needed to prevent the significant medical, psychological, and fiscal costs resulting from individuals receiving a false-positive HIV diagnosis.

  14. Pengaruh Kepuasan Kerja dan Komitmen Organisasi Terhadap Turnover Intention Karyawan (Studi Pada Bank Perkreditan Mitratama Arthabuana

    Directory of Open Access Journals (Sweden)

    Abdurrahim .

    2016-04-01

    Full Text Available This study aimed to identify and analyze the influence of job satisfaction (X1 and organizational commitment (X2 as independent variables either simultaneously or  individually  on  Turnover  Intention  (Y  as  the  dependent  variable  on  the employee of PT. BPR Mitratama Arthabuana Kertak Hanyar. This  was  an  explanatory  research  with  unit  analysis  of  PT.  BPR  Mitratama Arthabuana  Kertak  Hanyar.  The  sampling  technique  used  in  this  study  was saturated sample with 53 employees as population. Measurement of variables is done by using Likert Scale technique with weight scale from 1 to 5. Multiple linear  regression  statistical  technique  were  used  to  analyze  the  effect  of  job satisfaction  among  variables  (X1  and  organizational  commitment  (X2  on Turnover Intention (Y. Furthermore, to test the level of significance, the F test and t test with SPSS version 19 used. The study concluded that two independent variables simultaneously, namely job satisfaction variables (X1 and organizational commitment (X2 have significant relationship  to  Turnover  Intention  (Y  variable.  Meanwhile,  individually,  job satisfaction  variable  (X1  has  significant  negative  relationship  on  Turnover Intention  (Y,  as  well  as  the  organizational  commitment  variable  (X2  on  a Turnover Intention (Y.  Keywords :Job Satisfaction, Organizational Commitment, Turnover Intention

  15. Achilles tendinosis - Changes in biochemical composition and collagen turnover rate

    NARCIS (Netherlands)

    de Mos, Marieke; van El, Benno; DeGroot, Jeroen; Jahr, Holger; van Schie, Hans T. M.; van Arkel, Ewoud R.; Tol, Hans; Heijboer, Rien; van Osch, Gerjo J. V. M.; Verhaar, Jan A. N.

    Background: Understanding biochemical and structural changes of the extracellular matrix in Achilles tendinosis might be important for developing mechanism-based therapies. Hypothesis: In Achilles tendinosis, changes occur in biochemical composition and collagen turnover rate. Study Design:

  16. Job turnover and regional attrition among physiotherapists in northern Ontario.

    Science.gov (United States)

    Noh, S; Beggs, C E

    1993-01-01

    Results of an initial study indicated that the most significant factor affecting retention for Physiotherapists in Northern Ontario was perceived opportunity for career development. A follow-up study was completed two years later to determine: 1) actual job turnover and regional attrition among physiotherapists in Northern Ontario; and 2) the predictive validity of variables identified in the first study regarding job turnover and regional attrition. Job turnover occurred in 29.5% of those sampled and the regional attrition rate was 12%. Discriminant function analysis revealed factors affecting job turnover and regional attrition including professional experience, practice location, opportunity for career development and size of community of residence. Based on previous intention, indicated by participants, follow-up revealed that the initial study correctly predicted 77.5% of those who changed their jobs and 74.1% of those who left Northern Ontario. Identified factors provide direction for the development of strategies for recruitment and retention of physiotherapists.

  17. Global Distribution of Root Turnover in Terrestrial Ecosystems

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Estimates of root turnover rates were calculated from measurements of live root standing crop and belowground net primary production (BNPP) compiled from...

  18. Achilles tendinosis: Changes in biochemical composition and collagen turnover rate

    NARCIS (Netherlands)

    Mos, M. de; El, B. van; Groot, J. de; Jahr, H.; Schie, H.T.M. van; Arkel, E.R. van; Tol, H.; Heijboer, R.; Osch, G.J.V.M. van; Verhaar, J.A.N.

    2007-01-01

    Background: Understanding biochemical and structural changes of the extracellular matrix in Achilles tendinosis might be important for developing mechanism-based therapies. Hypothesis: In Achilles tendinosis, changes occur in biochemical composition and collagen turnover rate. Study Design:

  19. Report: Remedial Project Manager Turnover at Superfund Sites

    Science.gov (United States)

    Report #2001-M-000015, June 15, 2001. We determined that EPA Region III did not have formal procedures in place to mitigate continuity problems caused by turnover of EPA personnel in the Superfund program.

  20. Corporate governance mechanisms in family firms: Evidence from CEO turnovers

    OpenAIRE

    González, Maximiliano; Guzmán, Alexander; Pombo, Carlos; Trujillo, María Andréa

    2013-01-01

    Research Question/Issue: How sensitive is CEO turnover to firm performance in the context of family firms? Research Findings/Insights: Using a detailed database of mostly non-listed Colombian firms, we found that family ownership (direct and indirect through pyramidal structures) reduces the probability of CEO turnover when financial performance has been poor; however, we found that the opposite effect is true when families participate actively on the board of directors. These results hold tr...

  1. Telaah Hubungan Kepuasan Kerja Dan Komitmen Organisasional Terhadap Turnover Intention

    Directory of Open Access Journals (Sweden)

    Ali Amran

    2017-04-01

    ABSTRACT       Employees are the most important resources of company. They are human resources to do and move all of the activities of company. Therefore, company needs to keep and maintain their job satisfaction and organizational commitment in order to reduce the intention to leave the company (turnover intention. It is necessary to study the relationship among job satisfaction, organizational commitment and turnover intention. This will give benefit to determine the important values of employees’ job satisfaction and organizational commitment and its influences on turnover intention. The research methods are descriptive survey and verificative survey that is used to assess the performance of independent variables: those are job satisfaction and organizational commitment,  and dependent variable: that is turnover intention with doing observation to employees of PT. Alexindo Bekasi. The result of this research is there is influence of job satisfaction and organizational commitment on turnover intention. This research is the improvement of existing researches which can be applied in the other companies specially for the human resource or employee behavior field.   Keywords: Job Satisfaction, Organizational Commitment, Turnover Intention

  2. Reviewing Employee Turnover: Focusing on Proximal Withdrawal States and an Expanded Criterion

    Science.gov (United States)

    Hom, Peter W.; Mitchell, Terence R.; Lee, Thomas W.; Griffeth, Rodger W.

    2012-01-01

    We reconceptualize employee turnover to promote researchers' understanding and prediction of why employees quit or stay in employing institutions. A literature review identifies shortcomings with prevailing turnover dimensions. In response, we expand the conceptual domain of the turnover criterion to include multiple types of turnover (notably,…

  3. The impact of workplace relationships on engagement, well-being, commitment and turnover for nurses in Australia and the USA.

    Science.gov (United States)

    Brunetto, Yvonne; Xerri, Matthew; Shriberg, Art; Farr-Wharton, Rod; Shacklock, Kate; Newman, Stefanie; Dienger, Joy

    2013-12-01

    We examined the impact of workplace relationships (perceived organizational support, supervisor-nurse relationships and teamwork) on the engagement, well-being, organizational commitment and turnover intentions of nurses working in Australian and USA hospitals. In a global context of nurse shortages, knowledge about factors impacting nurse retention is urgently sought. We postulated, using the Social Exchange Theory, that nurses' turnover intentions would be affected by several factors and especially their relationships at work. Based on the literature review, data were collected via a self-report survey to test the hypotheses. A self-report survey was used to gather data in 2010-2012 from 510 randomly chosen nurses from Australian hospitals and 718 nurses from US hospitals. A multi-group structural equation modelling analysis identified significant paths and compared the impact between countries. The findings indicate that this model was more effective in predicting the correlations between variables for nurses in Australia compared with the USA. Most paths predicted were confirmed for Australia, except for the impact of teamwork on organizational commitment and turnover, plus the impact of engagement on turnover. In contrast, none of the paths related to supervisor-subordinate relationships was significant for the USA; neither were the paths from teamwork to organizational commitment or turnover. Our findings suggest that well-being is a predictor of turnover intentions, meaning that healthcare managers need to consider nurses' well-being in everyday decision-making, especially in the cost-cutting paradigm that pervades healthcare provision in nearly every country. This is important because nurses are in short supply and this situation will continue to worsen, because many countries have an ageing population. © 2013 John Wiley & Sons Ltd.

  4. Determinants of CEO Turnover in Publicand Private Firms in Denmark - CEO and Firm Characteristics

    DEFF Research Database (Denmark)

    Sponholtz, Carina

    turnover across a variety of firm types that di¤er with re-spect to the corporate governance issues they face. Our simple methodol-ogy to define CEO turnover results in turnover rates similar to those foundpreviously. Our results indicate that CEO characteristics are an important factor in explaining CEO...... governance issues they face. Our simple methodology to define CEO turnover results in turnover rates similar to those foundpreviously. Our results indicate that CEO characteristics are an important factor in explaining CEO turnover. Finally, the inverse relationshipbetween firm performance and CEO turnover......-employee data to study CEO turnover. Using this data we contribute tothe existing literature by examining the effect of previously unstudied individual characteristics on CEO turnover. Additionally, we are able toexamine CEO turnover across a variety of firm types that di¤er with respect to the corporate...

  5. Investigating the adequacy of the Competence-Turnover Intention Model: how does nursing competence affect nurses' turnover intention?

    Science.gov (United States)

    Takase, Miyuki; Teraoka, Sachiko; Kousuke, Yabase

    2015-03-01

    The aim of this study was to test the adequacy of the Competence-Turnover Intention Model, which was developed to identify how nursing competence could affect nurses' turnover intention (nurses' intention to voluntarily leave an organisation). Recent studies have suggested that the level of nursing competence is negatively related to nurses' intention to leave their jobs, suggesting that a lack of competence threatens both the quality and quantity of the nursing workforce. However, the mechanism of how nursing competence affects nurses' turnover intention has not been explored previously. A cross-sectional survey design was used. Surveys were distributed to 1337 Japanese registered nurses/midwives in October, 2013. The adequacy of the model was analysed using structural equation modelling. In total, 766 questionnaires were returned, with a return rate of 57%. The model fitted well with the data. The results showed that the level of nursing competence was related positively to the quantity of organisational rewards they felt they had received, and negatively related to the level of exhaustion they experienced. Moreover, the perceived organisational rewards and exhaustion were correlated with nurses' turnover intention through affective commitment. The Competence-Turnover Intention Model is useful for explaining how nursing competence impacts on their turnover intention. Clinical implications derived from the findings are that: promoting nursing competence is key to improving not only the quality of care provided by nurses, but also to retaining the nursing workforce, and the model can be used to develop strategies that would mitigate their turnover intention. © 2014 John Wiley & Sons Ltd.

  6. Low bone turnover phenotype in Rett syndrome

    DEFF Research Database (Denmark)

    Roende, Gitte; Petersen, Janne; Ravn, Kirstine

    2014-01-01

    Background:Patients with Rett syndrome (RTT) are at risk of having low bone mass and low-energy fractures.Methods:We characterised bone metabolism by both bone formation and resorption markers in blood in a RTT population of 61 girls and women and 122 well-matched healthy controls. Levels of N...

  7. Estimation of Employee Turnover with Competing Risks Models

    Directory of Open Access Journals (Sweden)

    Grzenda Wioletta

    2015-12-01

    Full Text Available Employee turnover accompanies every business organization, regardless of the industry and size. Nowadays, many companies struggle with problems related to the lack of sufficient information about the nature of employee turnover processes. Therefore, comprehensive analysis of these processes is necessary. This article aims to examine the turnover of employees from a big manufacturing company using competing risks models with covariates and without covariates. This technique allows to incorporate the information about the type of employment contract termination. Moreover, Cox proportional hazard model enables the researcher to analyse simultaneously multiple factors that affect employment duration. One of the major observations is that employee remuneration level differentiates most strongly the risk of job resignation.

  8. Taxonomic and functional turnover are decoupled in European peat bogs.

    Science.gov (United States)

    Robroek, Bjorn J M; Jassey, Vincent E J; Payne, Richard J; Martí, Magalí; Bragazza, Luca; Bleeker, Albert; Buttler, Alexandre; Caporn, Simon J M; Dise, Nancy B; Kattge, Jens; Zając, Katarzyna; Svensson, Bo H; van Ruijven, Jasper; Verhoeven, Jos T A

    2017-10-27

    In peatland ecosystems, plant communities mediate a globally significant carbon store. The effects of global environmental change on plant assemblages are expected to be a factor in determining how ecosystem functions such as carbon uptake will respond. Using vegetation data from 56 Sphagnum-dominated peat bogs across Europe, we show that in these ecosystems plant species aggregate into two major clusters that are each defined by shared response to environmental conditions. Across environmental gradients, we find significant taxonomic turnover in both clusters. However, functional identity and functional redundancy of the community as a whole remain unchanged. This strongly suggests that in peat bogs, species turnover across environmental gradients is restricted to functionally similar species. Our results demonstrate that plant taxonomic and functional turnover are decoupled, which may allow these peat bogs to maintain ecosystem functioning when subject to future environmental change.

  9. Changes of Protein Turnover in Aging Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Dhondt, Ineke; Petyuk, Vladislav A.; Bauer, Sophie; Brewer, Heather M.; Smith, Richard D.; Depuydt, Geert; Braeckman, Bart P.

    2017-07-05

    Protein turnover rates severely decline in aging organisms, including C. elegans. However, limited information is available on turnover dynamics at the individual protein level during aging. We followed changes in protein turnover at one-day resolution using a multiple-pulse 15Nlabeling and accurate mass spectrometry approach. Forty percent of the proteome shows gradual slowdown in turnover with age, whereas only few proteins show increased turnover. Decrease in protein turnover was consistent for only a minority of functionally related protein subsets, including tubulins and vitellogenins, whereas randomly diverging turnover patterns with age were the norm. Our data suggests increased heterogeneity of protein turnover of the translation machinery, whereas protein turnover of ubiquitin-proteasome and antioxidant systems are well-preserved over time. Hence, we presume that maintenance of quality control mechanisms is a protective strategy in aging worms, although the ultimate proteome collapse is inescapable.

  10. Bone Turnover Does Not Reflect Skeletal Aging in Older Hispanic Men with Type 2 Diabetes

    Science.gov (United States)

    Rianon, N.; McCormick, J.; Ambrose, C.; Smith, S. M.; Fisher-Hoch, S.

    2016-01-01

    The paradox of fragility fracture in the presence of non-osteoporotic bone mineral density in older patients with type 2 diabetes mellitus (DM2) makes it difficult to clinically predict fracture in this vulnerable group. Serum osteocalcin (OC), a marker of bone turnover, increases with normal skeletal aging indicating risk of fracture. However, OC has been reported to be lower in patients with DM2. An inverse association between higher glycated hemoglobin levels (HbA1c) and lower serum OC in older DM2 patients triggered discussions encouraging further investigation. A key question to be answered is whether changes in glucose metabolism is responsible for bone metabolic changes, ultimately leading to increased risk of fragility fractures in DM2 patients. While these studies were conducted among Caucasian and Asian populations, this has not been studied in Hispanic populations who suffer from a higher prevalence of DM2. The Cameron County Hispanic Cohort (CCHC) in Texas is a homogeneous Hispanic cohort known to have high prevalence of DM2 (30%). Our preliminary data from this cohort reported OC levels lower than the suggested threshold for fragility fracture in post-menopausal women. We further investigated whether bone turnover in older CCHC adults with DM2 show a normal pattern of skeletal aging. Samples and data were obtained from a nested cohort of 68 (21 men and 47 women) Hispanic older adults (=50 years) who had a diagnosis of DM2. Given high prevalence of uncontrolled DM2 in this cohort, we divided population into two groups: i) poor DM2 control with HbA1c level =8 (48% men and 38% women) and ii) good DM2 control with HbA1c level <8). A crosssectional analysis documented associations between serum OC and age adjusted HbA1c levels. There was no direct association between age and OC concentrations in our study. Higher HbA1c was associated with lower serum OC in men (odds ratio -6.5, 95% confidence interval -12.7 to - 0.3, p < 0.04). No significant associations

  11. Validity of Race, Ethnicity, and National Origin in Population-based Cancer Registries and Rapid Case Ascertainment Enhanced with a Spanish Surname List

    NARCIS (Netherlands)

    L.C. Clarke (Lisa C.); R.P. Rull (Rudolph P.); J.Z. Ayanian (John Z.); R. Boer (Robert); D. Deapen (Dennis); D. van West; K.L. Kahn (Katherine L.)

    2016-01-01

    textabstractBackground: Accurate information regarding race, ethnicity, and national origins is critical for identifying disparities in the cancer burden. Objectives: To examine the use of a Spanish surname list to improve the quality of race-related information obtained from rapid case

  12. Human turnover dynamics during sleep: Statistical behavior and its modeling

    Science.gov (United States)

    Yoneyama, Mitsuru; Okuma, Yasuyuki; Utsumi, Hiroya; Terashi, Hiroo; Mitoma, Hiroshi

    2014-03-01

    Turnover is a typical intermittent body movement while asleep. Exploring its behavior may provide insights into the mechanisms and management of sleep. However, little is understood about the dynamic nature of turnover in healthy humans and how it can be modified in disease. Here we present a detailed analysis of turnover signals that are collected by accelerometry from healthy elderly subjects and age-matched patients with neurodegenerative disorders such as Parkinson's disease. In healthy subjects, the time intervals between consecutive turnover events exhibit a well-separated bimodal distribution with one mode at ⩽10 s and the other at ⩾100 s, whereas such bimodality tends to disappear in neurodegenerative patients. The discovery of bimodality and fine temporal structures (⩽10 s) is a contribution that is not revealed by conventional sleep recordings with less time resolution (≈30 s). Moreover, we estimate the scaling exponent of the interval fluctuations, which also shows a clear difference between healthy subjects and patients. We incorporate these experimental results into a computational model of human decision making. A decision is to be made at each simulation step between two choices: to keep on sleeping or to make a turnover, the selection of which is determined dynamically by comparing a pair of random numbers assigned to each choice. This decision is weighted by a single parameter that reflects the depth of sleep. The resulting simulated behavior accurately replicates many aspects of observed turnover patterns, including the appearance or disappearance of bimodality and leads to several predictions, suggesting that the depth parameter may be useful as a quantitative measure for differentiating between normal and pathological sleep. These findings have significant clinical implications and may pave the way for the development of practical sleep assessment technologies.

  13. Bone turnover markers during pubertal development: relationships with growth factors and adipocytokines.

    Science.gov (United States)

    Jürimäe, Jaak; Mäestu, Jarek; Jürimäe, Toivo

    2010-01-01

    The rapid increase in skeletal mass that occurs during puberty is caused by increases in longitudinal growth as well as cortical thickness. The measurement of growth changes during puberty using two-dimensional (dual-energy X-ray absorptiometry) and/or three-dimensional (computed tomography, magnetic resonance imaging) measurement devices provides only a static representation of bone tissue parameters. The measurement of bone turnover markers provides a more dynamic picture of the nature of bone tissue that can be repeated at much shorter intervals during puberty. The bone turnover markers are products of osteoblasts and osteoclasts which can be measured in urine or blood. The increase in different markers of bone turnover coincides with the pubertal growth spurt and thereafter markers decline until they converge into adult values. The initiation of puberty is accompanied by increases in androgens and estrogens. The effects of sex hormones on bone mineral accrual are mediated mainly by growth hormone and insulin-like growth factor-1, but they also exert a direct effect on bone metabolism. Important determinants of bone mineral accrual during puberty include optimal nutritional status, body composition parameters and physical activity pattern. All of these determinants are related to the state of energy balance, while peripheral indicators of energy balance, such as different growth factors and adipocytokines, may also have a positive influence of the growing skeleton. Taken together, bone mineral accrual during puberty is a complex interaction between physical activity pattern, various body composition parameters, specific growth factors and adipocytokines, and also sex hormones. Copyright © 2010 S. Karger AG, Basel.

  14. Problematics of high employee turnover in hotel Thermal

    OpenAIRE

    Gistinger, Petr

    2016-01-01

    Bachelor´s thesis is focused on high employee turnover in a specific company. Thesis is divided into two parts. The first part consists of definitions, theoretical starting-points and methods connected with employee turnover. In the beginning of the second part the hotel is briefly introduced. In the main body of second part I have analysed the situation in the hotel based on internal documents, hotel´s official web page, official statistics and an interview with company´s manager. Using the ...

  15. Nonlicensed employee turnover in a long-term care facility.

    Science.gov (United States)

    Gaddy, T; Bechtel, G A

    1995-06-01

    The purpose of this study was to analyze nonlicensed employee turnover in a long-term care facility using Maslow's hierarchy of needs as a framework. During exit interviews, a convenience sample of 34 employees completed an attitudes and beliefs survey regarding their work environment. Findings were mixed; 39.6 percent of the employees stated positive personal relationships were a strength of the organization, although 24.3 percent resigned because of personal/staff conflicts. Financial concerns were not a major factor in their resignations. The study suggests that decreasing nonlicensed employee stress and increasing their personal satisfaction with patient care may decrease employee turnover.

  16. Fast-cycling unit of root turnover in perennial herbaceous plants in a cold temperate ecosystem

    Science.gov (United States)

    Sun, Kai; Luke McCormack, M.; Li, Le; Ma, Zeqing; Guo, Dali

    2016-01-01

    Roots of perennial plants have both persistent portion and fast-cycling units represented by different levels of branching. In woody species, the distal nonwoody branch orders as a unit are born and die together relatively rapidly (within 1-2 years). However, whether the fast-cycling units also exist in perennial herbs is unknown. We monitored root demography of seven perennial herbs over two years in a cold temperate ecosystem and we classified the largest roots on the root collar or rhizome as basal roots, and associated finer laterals as secondary, tertiary and quaternary roots. Parallel to woody plants in which distal root orders form a fast-cycling module, basal root and its finer laterals also represent a fast-cycling module in herbaceous plants. Within this module, basal roots had a lifespan of 0.5-2 years and represented 62-87% of total root biomass, thus dominating annual root turnover (60%-81% of the total). Moreover, root traits including root length, tissue density, and biomass were useful predictors of root lifespan. We conclude that both herbaceous and woody plants have fast-cycling modular units and future studies identifying the fast-cycling module across plant species should allow better understanding of how root construction and turnover are linked to whole-plant strategies.

  17. Fast-cycling unit of root turnover in perennial herbaceous plants in a cold temperate ecosystem.

    Science.gov (United States)

    Sun, Kai; McCormack, M Luke; Li, Le; Ma, Zeqing; Guo, Dali

    2016-01-21

    Roots of perennial plants have both persistent portion and fast-cycling units represented by different levels of branching. In woody species, the distal nonwoody branch orders as a unit are born and die together relatively rapidly (within 1-2 years). However, whether the fast-cycling units also exist in perennial herbs is unknown. We monitored root demography of seven perennial herbs over two years in a cold temperate ecosystem and we classified the largest roots on the root collar or rhizome as basal roots, and associated finer laterals as secondary, tertiary and quaternary roots. Parallel to woody plants in which distal root orders form a fast-cycling module, basal root and its finer laterals also represent a fast-cycling module in herbaceous plants. Within this module, basal roots had a lifespan of 0.5-2 years and represented 62-87% of total root biomass, thus dominating annual root turnover (60%-81% of the total). Moreover, root traits including root length, tissue density, and biomass were useful predictors of root lifespan. We conclude that both herbaceous and woody plants have fast-cycling modular units and future studies identifying the fast-cycling module across plant species should allow better understanding of how root construction and turnover are linked to whole-plant strategies.

  18. Fungal endophyte communities in the temperate fern Polystichum munitum show early colonization and extensive temporal turnover.

    Science.gov (United States)

    Younginger, Brett S; Ballhorn, Daniel J

    2017-08-16

    Fungal endophytes have been shown to colonize all land plants, yet surprisingly little attention has been given to their community composition in ferns. We examined the diversity and temporal turnover of fungal endophytes in foliar tissue of the temperate western sword fern, Polystichum munitum, comparing taxa in newly emerged leaflets and in the same fronds after 1 mo of exposure in the field. Utilizing next-generation sequencing, we sampled pinnae from P. munitum in spring, 2-3 d after they emerged. We additionally sampled pinnae 30 d later from the same fern blades. From these samples, we sequenced fungal DNA to characterize the initial colonization and temporal turnover of endophytes in the host. We demonstrate that P. munitum is abundantly colonized by endophytes in newly emerged foliar tissue. However, 1 mo later, the community composition undergoes a marked shift: the overall richness of endophytes increases, but the evenness of the community wanes as a single taxon, Flagellospora fusarioides, comes to dominate. We conclude that P. munitum hosts a variety of fungal endophyte taxa, similarly to other land plants. However, the rapid shift of the endophyte community we report is an unprecedented observation. Therefore, we further conclude that repeated sampling should be the standard in endophyte studies, because single sampling events are not sufficient to capture the dynamic nature of these cryptic microfungi. © 2017 Botanical Society of America.

  19. Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists.

    Science.gov (United States)

    Kohler, Annegret; Kuo, Alan; Nagy, Laszlo G; Morin, Emmanuelle; Barry, Kerrie W; Buscot, Francois; Canbäck, Björn; Choi, Cindy; Cichocki, Nicolas; Clum, Alicia; Colpaert, Jan; Copeland, Alex; Costa, Mauricio D; Doré, Jeanne; Floudas, Dimitrios; Gay, Gilles; Girlanda, Mariangela; Henrissat, Bernard; Herrmann, Sylvie; Hess, Jaqueline; Högberg, Nils; Johansson, Tomas; Khouja, Hassine-Radhouane; LaButti, Kurt; Lahrmann, Urs; Levasseur, Anthony; Lindquist, Erika A; Lipzen, Anna; Marmeisse, Roland; Martino, Elena; Murat, Claude; Ngan, Chew Y; Nehls, Uwe; Plett, Jonathan M; Pringle, Anne; Ohm, Robin A; Perotto, Silvia; Peter, Martina; Riley, Robert; Rineau, Francois; Ruytinx, Joske; Salamov, Asaf; Shah, Firoz; Sun, Hui; Tarkka, Mika; Tritt, Andrew; Veneault-Fourrey, Claire; Zuccaro, Alga; Tunlid, Anders; Grigoriev, Igor V; Hibbett, David S; Martin, Francis

    2015-04-01

    To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergent evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.

  20. Firm-level innovation activity, employee turnover and HRM practices

    DEFF Research Database (Denmark)

    Eriksson, Tor; Qin, Zhihua; Wang, Wenjing

    2014-01-01

    This paper examines the relationship between employee turnover, HRM practices and innovation in Chinese firms in five high technology sectors. We estimate hurdle negative binomial models for count data on survey data allowing for analyses of the extensive as well as intensive margins of firms...

  1. Exercise Enhances Whole-Body Cholesterol Turnover in Mice

    NARCIS (Netherlands)

    Meissner, Maxi; Havinga, Rick; Boverhof, Renze; Kema, Ido; Groen, Albert K.; Kuipers, Folkert

    MEISSNER, M., R. HAVINGA, R. BOVERHOF, I. KEMA, A. K. GROEN, and F. KUIPERS. Exercise Enhances Whole-Body Cholesterol Turnover in Mice. Med. Sci. Sports Exerc., Vol. 42, No. 8, pp. 1460-1468, 2010. Purpose: Regular exercise reduces cardiovascular risk in humans by reducing cholesterol levels, but

  2. Oxidative Criteria And Somebone Turnover Markers In Beta ...

    African Journals Online (AJOL)

    Bone disease in beta-thalassemic patients has multifactorial etiology; increased iron stores and per-oxidative stress are involved factors. This study aimed to investigate the relationship between some bone turnover markers and some oxidants, antioxidants parameters of betathalassemic patients. The study included 50 ...

  3. Organisational culture of hospitals to predict turnover intentions of ...

    African Journals Online (AJOL)

    The objective of this study was to determine if organisational culture predicts turnover intentions of professional nurses. A predictive model with organisational culture and various proposed mediating variables, namely knowledge sharing, organisational commitment, organisational citisenship behaviour and job satisfaction, ...

  4. 41 CFR 109-27.5002 - Stores inventory turnover ratio.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Stores inventory....5002 Stores inventory turnover ratio. Comparison of investment in stores inventories to annual issues... ratio of 2.0, shall be established for each stores using activity. It is recognized, however, that...

  5. Effects of ractopamine and gender on protein turnover in skeletal ...

    African Journals Online (AJOL)

    Effects of the β-agonist, ractopamine-HCl (ractopamine), on skeletal muscle protein turnover were evaluated in 16 steers (512 kg) and 16 heifers (473 kg). Treatments were arranged in a 2 × 2 factorial design and included gender (steer vs. heifer) and ractopamine (0 or 200 mg/d). Steers were implanted with 120 mg ...

  6. The Effects of Turnover: What We Know about Teacher Attrition

    Science.gov (United States)

    DeAngelis, Karen

    2012-01-01

    School business officials are likely to know better than anyone else about the financial costs to districts and schools associated with teacher attrition. Perhaps less well-known, though, is what else has been learned about this issue in recent years--information that may affect how one thinks about teacher turnover. Here is some of that research:…

  7. Bone turnover biomarkers in obese postmenopausal Saudi women ...

    African Journals Online (AJOL)

    Background: There is a high prevalence of diabetes mellitus type-2 (T2DM) and osteoporosis are problems worldwide. In this study, we evaluated the correlation between T2DM and bone turnover in diabetic obese postmenopausal Saudi women. Subjects and Methods: The present study included total of 65 T2-DM obese ...

  8. Prediction of Military Turnover Using Intentions, Satisfaction, and Performance.

    Science.gov (United States)

    Knapp, Deirdre J.; And Others

    Although researchers have examined the link between job attitudes and turnover, some studies claim that civilian samples may not be generalizable to military personnel. This paper addresses two central questions: (1) To what extent does job satisfaction, job performance, and reenlistment intentions predict reenlistment behavior?; (2) To what…

  9. Influence of Religiosity on Turnover Intention: Empirical Evidence ...

    African Journals Online (AJOL)

    This study examined the influence of employees' religiosity on their turnover intentions. The ex-post facto research design and the convenient sampling technique were employed in this study. A hundred and forty-nine (149) employees in Lagos and Ogun States of Nigeria were sampled as the study participants.

  10. Turnover of nursing employees in a Gauteng hospital group

    Directory of Open Access Journals (Sweden)

    Japie Greyling

    2010-03-01

    Full Text Available Orientation: The South African nursing profession is in a crisis as professional nurses leave the country in search of lucrative work overseas.Research purpose: The purpose of this study was to investigate individual determinants of voluntary turnover to identify a risk-group profile.Motivation for the study: Nursing employers should have a clearer understanding of the dynamics around nurses’ turnover behaviour and embark on strategies to retain their talent.Research design, approach and method: A survey measuring voluntary turnover was conducted among 262 professional and assistant nurses in three selected hospitals in Gauteng province using the McCarthy, Tyrrell and Cronin (2002 instrument. Pearson’s chi square with Yates’s continuity correction tested the relationship among the variables presented in a contingency table, in other words the risk group and each of the individual determinants.Main findings: Discontent with salaries was the major determinant of the nurses’ resignation. Organisational causes were nursing practices, the work environment, physical-emotional costs and employment opportunities after resignation.Practical/managerial implications: Hospital management could indeed establish a good rapport with nursing staff while facilitating respectful and ethical conduct by doctors towards nursing staff. Putting into place effective labour practices and business strategies could improve job satisfaction in the workplace.Contribution/value-add: This study contributed to a greater understanding of the personal and organisational determinants of the turnover of nurses in South African hospitals.

  11. Resilience, job satisfaction and anticipated turnover in nurse leaders.

    Science.gov (United States)

    Hudgins, Tracy Ann

    2016-01-01

    The aim was to identify relationships between resilience, job satisfaction and anticipated turnover among nurse leaders. Despite the reported value of resilience, there is a lack of research on resilience in nurse leaders. This study examined how nurse leaders describe their resilience and the relationship it has with job satisfaction and anticipated turnover. This quantitative study used a sample of 89 nurse leaders (bedside, department, division and organisational) from a multi-hospital health-care system in southwestern Virginia. There are significant relationships between resilience, job satisfaction and anticipated turnover. Additionally, it was found that the variables of job satisfaction and anticipated turnover significantly overlapped in their meaning and created a new construct of intent to remain (ITR) that has a statistically significant relationship with resilience. A stable nursing team has a positive impact on improving patient outcomes. To mitigate the impact of a nursing shortage, nurse leaders can enhance their own resilience and then recruit, hire and retain resilient staff nurses in an effort to improve nurses' ITR. With higher resilience, nurse leaders are more likely to intend to remain in their leadership positions. © 2015 John Wiley & Sons Ltd.

  12. Chinese Teachers' Work Stress and Their Turnover Intention

    Science.gov (United States)

    Liu, Shujie; Onwuegbuzie, Anthony J.

    2012-01-01

    This survey study employed qualitative dominant mixed research to explore the sources of teacher stress in China and the possible reasons for Chinese teachers' turnover intention. The data were collected in Jilin Province of China, and 510 teachers participated in the survey. Quantitatively, 40.4% of the surveyed teachers reported that they…

  13. Effects of ractopamine and gender on protein turnover in skeletal ...

    African Journals Online (AJOL)

    p2492989

    Effects of the β-agonist, ractopamine-HCl (ractopamine), on skeletal muscle protein turnover were evaluated in ... The increase in shear force of m. longissimus from cattle fed β-agonists suggests that muscle protein degradation is ..... Cimaterol-induced muscle hypertrophy and altered endocrine status in lambs. J. Anim. Sci.

  14. Teacher Turnover: An Issue of Workgroup Racial Diversity

    Science.gov (United States)

    Sohn, Kitae

    2009-01-01

    One neglected aspect of the teacher labor supply is a recent increase in the proportion of minority teachers. Using the Schools and Staffing Survey and the Teacher Follow-up Survey, one can estimate the relationship between workgroup racial diversity and the turnover of White teachers. This approach finds that young White teachers are more likely…

  15. Employees as Customers: Exploring Service Climate, Employee Patronage, and Turnover

    Science.gov (United States)

    Abston, Kristie A.; Kupritz, Virginia W.

    2011-01-01

    The role of retail employees as customers was explored by quantitatively examining the influence of service climate and employee patronage on employee turnover intentions. Employees representing all shifts in two stores of a national retailer participated. Results indicated that employee patronage partially mediates the effects of service climate…

  16. Non-local competition drives both rapid divergence and prolonged stasis in a model of speciation in populations with degenerate resource consumption

    Directory of Open Access Journals (Sweden)

    Atamas Nicholas

    2012-12-01

    Full Text Available Abstract The theory of speciation is dominated by adaptationist thinking, with less attention to mechanisms that do not affect species adaptation. Degeneracy – the imperfect specificity of interactions between diverse elements of biological systems and their environments – is key to the adaptability of populations. A mathematical model was explored in which population and resource were distributed one-dimensionally according to trait value. Resource consumption was degenerate – neither strictly location-specific nor location-independent. As a result, the competition for resources among the elements of the population was non-local. Two modeling approaches, a modified differential-integral Verhulstian equation and a cellular automata model, showed similar results: narrower degeneracy led to divergent dynamics with suppression of intermediate forms, whereas broader degeneracy led to suppression of diversifying forms, resulting in population stasis with increasing phenotypic homogeneity. Such behaviors did not increase overall adaptation because they continued after the model populations achieved maximal resource consumption rates, suggesting that degeneracy-driven distributed competition for resources rather than selective pressure toward more efficient resource exploitation was the driving force. The solutions were stable in the presence of limited environmental stochastic variability or heritable phenotypic variability. A conclusion was made that both dynamic diversification and static homogeneity of populations may be outcomes of the same process – distributed competition for resource not affecting the overall adaptation – with the difference between them defined by the spread of trait degeneracy in a given environment. Thus, biological degeneracy is a driving force of both speciation and stasis in biology, which, by themselves, are not necessarily adaptive in nature.

  17. A Social Network Perspective on Turnover Intentions : The Role of Distributive Justice and Social Support

    NARCIS (Netherlands)

    Soltis, Scott M.; Agneessens, Filip; Sasovova, Zuzana; Labianca, Giuseppe (Joe)

    Organizations are increasingly concerned about retaining human talent, particularly within knowledge-based industries where turnover is expensive. Our study employs a social network perspective to explore the influence of employees' formal and informal workplace relationships on their turnover

  18. Prostate Cancer Metastases to Bone: Role of High Bone Turnover Induced by Androgen Deprivation

    National Research Council Canada - National Science Library

    Padalecki, Susan

    2002-01-01

    .... Treatment with androgen deprivation therapy leads to an increase in bone turnover as indicated by the loss of bone mineral density and the increase in markers of bone turnover in patients on treatment...

  19. Forward modeling of fluctuating dietary 13C signals to validate 13C turnover models of milk and milk components from a diet-switch experiment.

    Directory of Open Access Journals (Sweden)

    Alexander Braun

    Full Text Available Isotopic variation of food stuffs propagates through trophic systems. But, this variation is dampened in each trophic step, due to buffering effects of metabolic and storage pools. Thus, understanding of isotopic variation in trophic systems requires knowledge of isotopic turnover. In animals, turnover is usually quantified in diet-switch experiments in controlled conditions. Such experiments usually involve changes in diet chemical composition, which may affect turnover. Furthermore, it is uncertain if diet-switch based turnover models are applicable under conditions with randomly fluctuating dietary input signals. Here, we investigate if turnover information derived from diet-switch experiments with dairy cows can predict the isotopic composition of metabolic products (milk, milk components and feces under natural fluctuations of dietary isotope and chemical composition. First, a diet-switch from a C3-grass/maize diet to a pure C3-grass diet was used to quantify carbon turnover in whole milk, lactose, casein, milk fat and feces. Data were analyzed with a compartmental mixed effects model, which allowed for multiple pools and intra-population variability, and included a delay between feed ingestion and first tracer appearance in outputs. The delay for milk components and whole milk was ~12 h, and that of feces ~20 h. The half-life (t½ for carbon in the feces was 9 h, while lactose, casein and milk fat had a t½ of 10, 18 and 19 h. The (13C kinetics of whole milk revealed two pools, a fast pool with a t½ of 10 h (likely representing lactose, and a slower pool with a t½ of 21 h (likely including casein and milk fat. The diet-switch based turnover information provided a precise prediction (RMSE ~0.2 ‰ of the natural (13C fluctuations in outputs during a 30 days-long period when cows ingested a pure C3 grass with naturally fluctuating isotope composition.

  20. Substrate turnover at low carbon concentrations in a model drinking water distribution system

    DEFF Research Database (Denmark)

    Boe-Hansen, Rasmus; Albrechtsen, Hans-Jørgen; Arvin, Erik

    2002-01-01

    utilisation and bacterial growth at low nutrient conditions in a model distribution system. The model system consisted of two loops in series, where flow rate and retention time were controlled independently. Spiking the drinking water of the model system with two different environmentally realistic......Water quality changes caused by microbial activity in the distribution network can cause serious problems. Reducing the amount of microbial available substrate may be an effective way to control bacterial aftergrowth. The purpose of the present study was to study the kinetics of substrate...... concentrations of carbon allowed for a close monitoring of the kinetics of substrate turnover (less than 10 μg C/L 14C-benzoic acid was added). The mineralisation of benzoic acid was rapid and could be modelled by a no-growth Monod expression using a maximum degradation rate of 0.59 μg C/L/h and a half...

  1. Quantitative analysis of endocytosis and turnover of epidermal growth factor (EGF) and EGF receptor.

    Science.gov (United States)

    Sorkin, Alexander; Duex, Jason E

    2010-03-01

    Binding of epidermal growth factor (EGF) to the EGF receptor (EGFR) initiates signal transduction, ultimately leading to altered gene expression. Ligand-activated EGFR is also rapidly internalized and then targeted to lysosomes for degradation or recycled back to the plasma membrane. Endocytosis is a major regulator of EGFR signaling. Therefore, elucidation of the mechanisms of EGFR endocytosis is essential for a better understanding of EGFR biology. In order to achieve a comprehensive analysis of these mechanisms, reliable methods for measuring the rates of EGFR protein turnover and the rate parameters for individual steps of EGFR endocytic trafficking must be employed. The protocols in this unit describe methodologies to measure the rates of EGFR synthesis and degradation, to monitor EGF-induced down-regulation of surface EGFR, to measure the kinetic rate parameters of internalization, recycling, and degradation of radiolabeled EGF, and to perform radioiodination of EGF by the chloramine T method.

  2. Hubungan Stres Kerja dengan Intensi Turnover Pada Karyawan Bank di Medan

    OpenAIRE

    Salim, Melinda

    2017-01-01

    Human is important resources in industry or organizational sector. Human resources become one of the most important successors in an organization. Number of turnovers that are increasing from time to time show that turnover intention between workers has increased too. The sector with higher turnover is financial sectors. Turnover intention is caused by work related stress that happened to the bank workers. The aim of this research is to see whether there is correlation betwe...

  3. Vitamin D status, dietary intake, and bone turnover in female Soldiers during military training: a longitudinal study

    Directory of Open Access Journals (Sweden)

    Lutz Laura J

    2012-08-01

    Full Text Available Abstract Background Vitamin D is an essential nutrient for maintaining bone health, to include protecting against stress fracture during periods of rapid bone turnover. The objective of this longitudinal, observational study was to assess vitamin D status, biomarkers of bone turnover, and vitamin D and calcium intake in female Soldiers (n = 91 during US Army basic combat training (BCT. Methods Anthropometric, biological and dietary intake data were collected at wk 0, 3, 6, and 9 of the 10 wk BCT course. Mixed models repeated measures ANOVAs were used to assess main effects of time, race, and time-by-race interactions. Results White volunteers experienced a decrease in serum 25(OHD levels, whereas non-white volunteers experienced an increase during BCT. However, serum 25(OHD levels were lower in non-whites than whites at all timepoints (P-interaction  Conclusions These findings demonstrate that female Soldiers experience dynamic changes in vitamin D status coupled with increased bone turnover and potentially inadequate vitamin D and calcium intake during military training.

  4. Is high employee turnover really harmful?: An empirical test using company records

    NARCIS (Netherlands)

    Glebbeek, A.C.; Bax, E.H.

    2004-01-01

    We tested the hypothesis that employee turnover and firm performance have an inverted U-shaped relationship: overly high or low turnover is harmful. Our analysis was based on economic performance data from 110 offices of a temporary employment agency. These offices had high variation in turnover but

  5. When the Going Gets Tough: Direct, Buffering and Indirect Effects of Social Support on Turnover Intention

    Science.gov (United States)

    Pomaki, Georgia; DeLongis, Anita; Frey, Daniela; Short, Kathy; Woehrle, Trish

    2010-01-01

    We examined the role of social support in turnover intention among new teachers. First, we tested and found evidence for a direct negative relationship between social support and turnover intention. Second, we tested the social support buffer hypothesis, and found that teachers with higher social support had lower turnover intention in the face of…

  6. To leave or not to leave : When receiving interpersonal citizenship behavior influences an employee's turnover intention

    NARCIS (Netherlands)

    Regts, Gerdien; Molleman, Eric

    Given that few studies have examined relational bases for voluntary employee turnover, the purpose of the article is to examine whether work relationships explain employee turnover intention. Adopting a social relational perspective on employee turnover, we investigated the effect of receiving

  7. Effect of phylloquinone supplementation on biochemical markers of vitamin K status and bone turnover in postmenopausal women

    DEFF Research Database (Denmark)

    Bugel, Susanne; Sorensen, A. Dorthe; Hels, Ole

    2007-01-01

    of increasing phylloquinone intakes above the usual dietary intake for 6 weeks on biochemical markers of vitamin K status and bone turnover in postmenopausal women. Thirty-one postmenopausal women completed this 3 X 6-week randomised cross-over study, in which volunteers were supplemented with 0 (placebo), 200......, pyridinoline and deoxypyridinoline) and urinary gamma-carboxyglutarnate were unaffected by phylloquinone supplementation. In conclusion, while daily supplementation with 200 and 500 mu g phylloquinone/d for 6 weeks increased vitamin K status in postmenopausal women, it had no effect on bone turnover.......While current intakes of phylloquinone (vitamin K-1) in many populations are believed to be sufficient to maintain normal blood coagulation, these may be insufficient to cover the requirements for optimal bone metabolism. Therefore, the objective of the present study was to investigate the effect...

  8. Self-Reported HIV-Positive Status But Subsequent HIV-Negative Test Result Using Rapid Diagnostic Testing Algorithms Among Seven Sub-Saharan African Military Populations

    Science.gov (United States)

    2017-07-07

    in many sub-Saharan African countries, and extensive laboratory testing has con- firmed HIV RDTs have excellent sensitivity and specificity. However... interpretation of results. We conducted HIV serosur- veys in seven sub-Saharan African military populations and recorded the frequency of per- sonnel...positive results, such as greater adherence to quality assurance guidelines and prevalence-specific HIV testing algorithms as described in the World

  9. Response of bone turnover markers to three oral bisphosphonate therapies in postmenopausal osteoporosis: the TRIO study.

    Science.gov (United States)

    Naylor, K E; Jacques, R M; Paggiosi, M; Gossiel, F; Peel, N F A; McCloskey, E V; Walsh, J S; Eastell, R

    2016-01-01

    We used bone turnover markers to identify women who responded to bisphosphonate treatment for osteoporosis. Response was more likely with alendronate and ibandronate than risedronate. There was a greater decrease in bone markers if baseline bone turnover markers were higher and if the patient took more than 80 % of her medication. Biochemical response to bisphosphonate therapy can be assessed using either a decrease in bone turnover marker beyond the least significant change (LSC) or a reduction to within a reference interval (RI). We compared the performance of these target responses and determined whether response was related to the type of bisphosphonate, compliance and baseline bone turnover markers. Biochemical responses to three oral bisphosphonates were assessed in an open, controlled trial comprising 172 postmenopausal osteoporotic women (age 53-84 years), randomised to alendronate, ibandronate or risedronate, plus calcium and vitamin D supplementation for 2 years. The LSC for each marker was derived within the study population, whereas RIs were obtained from a control group of healthy premenopausal women (age 35-40 years). Over 70 % of women achieved a target response for serum CTX and PINP, irrespective of the approach used. The percentage decrease at 12 weeks was greater for women with baseline PINP above the RI -63 % (difference 13 %, 95 % CI 0 to 27.1, P = 0.049) and good compliance -67 % (difference 15.9 %, 95 % CI 6.3 to 25.5, P = 0.001). Responders had a greater increase in spine bone density compared to nonresponders; for example 6.2 vs. 2.3 % (difference 3.9 %, 95 % CI 1.6 to 6.3, P = 0.0011) for PINP LSC. The magnitude of change in bone markers was greater with ibandronate and alendronate than risedronate. Both approaches to response identified similar proportions of women as responders. Nonresponders had smaller increases in BMD, and we suggest that biochemical assessment of response is a useful tool for the management of women with

  10. Identification of cardiomyocyte nuclei and assessment of ploidy for the analysis of cell turnover

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, Olaf; Zdunek, Sofia [Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm (Sweden); Alkass, Kanar; Druid, Henrik [Department of Forensic Medicine, Karolinska Institutet, SE-171 77 Stockholm (Sweden); Bernard, Samuel [CNRS UMR5208, Institut Camille Jordan, Universite Claude Bernard Lyon 1 (France); Frisen, Jonas, E-mail: jonas.frisen@ki.se [Department of Cell and Molecular Biology, Karolinska Institutet, SE-171 77 Stockholm (Sweden)

    2011-01-15

    Assays to quantify myocardial renewal rely on the accurate identification of cardiomyocyte nuclei. We previously {sup 14}C birth dated human cardiomyocytes based on the nuclear localization of cTroponins T and I. A recent report by Kajstura et al. suggested that cTroponin I is only localized to the nucleus in a senescent subpopulation of cardiomyocytes, implying that {sup 14}C birth dating of cTroponin T and I positive cell populations underestimates cardiomyocyte renewal in humans. We show here that the isolation of cell nuclei from the heart by flow cytometry with antibodies against cardiac Troponins T and I, as well as pericentriolar material 1 (PCM-1), allows for isolation of close to all cardiomyocyte nuclei, based on ploidy and marker expression. We also present a reassessment of cardiomyocyte ploidy, which has important implications for the analysis of cell turnover, and iododeoxyuridine (IdU) incorporation data. These data provide the foundation for reliable analysis of cardiomyocyte turnover in humans.

  11. The potential effects of climate change on amphibian distribution, range fragmentation and turnover in China

    Directory of Open Access Journals (Sweden)

    Ren-Yan Duan

    2016-07-01

    Full Text Available Many studies predict that climate change will cause species movement and turnover, but few have considered the effect of climate change on range fragmentation for current species and/or populations. We used MaxEnt to predict suitable habitat, fragmentation and turnover for 134 amphibian species in China under 40 future climate change scenarios spanning four pathways (RCP2.6, RCP4.5, RCP6 and RCP8.5 and two time periods (the 2050s and 2070s. Our results show that climate change may cause a major shift in spatial patterns of amphibian diversity. Amphibians in China would lose 20% of their original ranges on average; the distribution outside current ranges would increase by 15%. Suitable habitats for over 90% of species will be located in the north of their current range, for over 95% of species in higher altitudes (from currently 137–4,124 m to 286–4,396 m in the 2050s or 314–4,448 m in the 2070s, and for over 75% of species in the west of their current range. Also, our results predict two different general responses to the climate change: some species contract their ranges while moving westwards, southwards and to higher altitudes, while others expand their ranges. Finally, our analyses indicate that range dynamics and fragmentation are related, which means that the effects of climate change on Chinese amphibians might be two-folded.

  12. Harmful filamentous cyanobacteria favoured by reduced water turnover with lake warming

    Science.gov (United States)

    Posch, Thomas; Köster, Oliver; Salcher, Michaela M.; Pernthaler, Jakob

    2012-11-01

    Anthropogenic-induced changes in nutrient ratios have increased the susceptibility of large temperate lakes to several effects of rising air temperatures and the resulting heating of water bodies. First, warming leads to stronger thermal stratification, thus impeding natural complete water turnover (holomixis), which compensates for oxygen deficits in the deep zones. Second, increased water temperatures and nutrient concentrations can directly favour the growth of harmful algae. Thus, lake-restoration programmes have focused on reducing nutrients to limit toxic algal blooms. Here we present evidence that the ubiquitous harmful cyanobacterium Planktothrix rubescens has become the dominant species in a large lake during the past four decades, although the phosphorus content of the ecosystem decreased fivefold. However, the nitrogen input was not diminished concomitantly, favouring this non-N2-fixing cyanobacterium owing to increased N:P ratios. P. rubescens contains gas vesicles that allow for buoyancy to accumulate within the depth of optimal irradiance. As the toxic cyanobacterium has low consumption by predators, water turnover represents the main mechanism of seasonal population control. Thus, unidirectional lake-restoration measures in parallel with recurrent absence of holomixis owing to lake warming may lead to similar undesired effects that have formerly emerged from fertilization.

  13. Performance and carbon turnover in fast- and slow-growing broilers submitted to cyclic heat stress and fed on high-protein diets.

    Science.gov (United States)

    Campos, D M B; Macari, M; Fernadez-Alarcon, M F; Nogueira, W C L; de Souza, F A; Hada, F H; Lunedo, R; Denadai, J C

    2016-01-01

    Two experiments were conducted to test the hypothesis that when using similar protein/amino acid diets and environment temperature conditions, the performance and carbon turnover in muscle and liver tissues, as measured by the incorporation of stable isotopes ((13)C/(12)C), must be different between fast-growing Cobb 500® and slow-growing Label Rouge broilers. For both experiments (Cobb and Label Rouge), 21-d-old birds were distributed in a completely randomised, 3 × 3 factorial design; three environmental temperatures (cyclic heat stress ad libitum, 22°C ad libitum, and 22°C restricted) and three crude protein concentrations (189.1, 210 and 220 g/kg CP) were used. The Cobb 500® had better performance with higher concentrations of crude protein. Cyclic heat stress (a temperature factor), negatively affected this genetic strain's performance. For the Label Rouge birds, the crude protein concentrations in the diet presented inconsistent results and cyclic heat stress did not affect the performance. The carbon turnover rate was affected in the Cobb 500® strain, with a high protein content reducing carbon turnover in the evaluated tissues (liver and muscles). Feed intake had a greater impact on carbon turnover rates than cyclic heat stress. The Label Rouge birds were not affected by the evaluated factors, suggesting that genetic improvement has a leading role on tissue carbon turnover. There is a genetic influence on carbon turnover in the liver and muscle tissues of broiler chickens. In addition, genetically fast-growing broilers are more susceptible to variations in diet composition and environmental temperature than less rapidly growing animals.

  14. Nursing assistant turnover in nursing homes and need satisfaction.

    Science.gov (United States)

    Caudill, M; Patrick, M

    1989-06-01

    1. Level of Maslow's Hierarchy of Needs is basic physiological needs measured by salary, adequate housing, and food. Attainment of these needs increased the length of stay of nursing assistants in nursing homes. 2. Safety and security (level 2) influenced length of stay of nursing assistants. Those with benefits of retirement, vacation, and holiday pay tended to have less turnover. 3. Praise by the patient and family was most important to nursing assistants. Belonging to a peer group and praise by charge nurse also decreased turnover of nursing assistants (level 3). 4. Level 4, self-esteem measured by input into decisions and being able to criticize, increased length of stay of nursing assistants.

  15. Keratin dynamics: modeling the interplay between turnover and transport.

    Science.gov (United States)

    Portet, Stéphanie; Madzvamuse, Anotida; Chung, Andy; Leube, Rudolf E; Windoffer, Reinhard

    2015-01-01

    Keratin are among the most abundant proteins in epithelial cells. Functions of the keratin network in cells are shaped by their dynamical organization. Using a collection of experimentally-driven mathematical models, different hypotheses for the turnover and transport of the keratin material in epithelial cells are tested. The interplay between turnover and transport and their effects on the keratin organization in cells are hence investigated by combining mathematical modeling and experimental data. Amongst the collection of mathematical models considered, a best model strongly supported by experimental data is identified. Fundamental to this approach is the fact that optimal parameter values associated with the best fit for each model are established. The best candidate among the best fits is characterized by the disassembly of the assembled keratin material in the perinuclear region and an active transport of the assembled keratin. Our study shows that an active transport of the assembled keratin is required to explain the experimentally observed keratin organization.

  16. Matrix metalloproteinases in fish biology and matrix turnover.

    Science.gov (United States)

    Pedersen, Mona E; Vuong, Tram T; Rønning, Sissel B; Kolset, Svein O

    2015-01-01

    Matrix metalloproteinases have important functions for tissue turnover in fish, with relevance both for the fish industry and molecular and cellular research on embryology, inflammation and tissue repair. These metalloproteinases have been studied in different fish types, subjected to both aquaculture and experimental conditions. This review highlights studies on these metalloproteinases in relation to both fish quality and health and further, the future importance of fish for basic research studies. Copyright © 2015. Published by Elsevier B.V.

  17. Effects of carbon turnover time on terrestrial ecosystem carbon storage

    Science.gov (United States)

    Yan, Yaner; Zhou, Xuhui; Jiang, Lifeng; Luo, Yiqi

    2017-12-01

    Carbon (C) turnover time is a key factor in determining C storage capacity in various plant and soil pools as well as terrestrial C sink in a changing climate. However, the effects of C turnover time on ecosystem C storage have not been well explored. In this study, we compared mean C turnover times (MTTs) of ecosystem and soil, examined their variability to climate, and then quantified the spatial variation in ecosystem C storage over time from changes in C turnover time and/or net primary production (NPP). Our results showed that mean ecosystem MTT based on gross primary production (GPP; MTTEC_GPP = Cpool/GPP, 25.0 ± 2.7 years) was shorter than soil MTT (MTTsoil = Csoil/NPP, 35.5 ± 1.2 years) and NPP-based ecosystem MTT (MTTEC_NPP = Cpool/NPP, 50.8 ± 3 years; Cpool and Csoil referred to ecosystem or soil C storage, respectively). On the biome scale, temperature is the best predictor for MTTEC (R2 = 0.77, p < 0.001) and MTTsoil (R2 = 0.68, p < 0.001), while the inclusion of precipitation in the model did not improve the performance of MTTEC (R2 = 0.76, p < 0.001). Ecosystem MTT decreased by approximately 4 years from 1901 to 2011 when only temperature was considered, resulting in a large C release from terrestrial ecosystems. The resultant terrestrial C release caused by the decrease in MTT only accounted for about 13.5 % of that due to the change in NPP uptake (159.3 ± 1.45 vs. 1215.4 ± 11.0 Pg C). However, the larger uncertainties in the spatial variation of MTT than temporal changes could lead to a greater impact on ecosystem C storage, which deserves further study in the future.

  18. Stoichiometry and Turnover of the Stator and Rotor.

    Science.gov (United States)

    Morimoto, Yusuke V; Minamino, Tohru

    2017-01-01

    Fluorescence imaging techniques using green fluorescent protein (GFP) and related fluorescent proteins are utilized to monitor and analyze a wide range of biological processes in living cells. Stepwise photobleaching experiments can determine the stoichiometry of protein complexes. Fluorescence recovery after photobleaching (FRAP) experiments can reveal in vivo dynamics of biomolecules. In this chapter, we describe methods to detect the subcellular localization, stoichiometry, and turnovers of stator and rotor components of the Salmonella flagellar motor.

  19. Outcomes of Cataract Surgery in Urban and Rural Population in the South Indian State of Andhra Pradesh: Rapid Assessment of Visual Impairment (RAVI) Project.

    Science.gov (United States)

    Marmamula, Srinivas; Khanna, Rohit C; Shekhar, Konegari; Rao, Gullapalli N

    2016-01-01

    To assess the visual outcomes after cataract surgery among urban and rural population aged ≥40 years in the South India state of Andhra Pradesh. A population based cross-sectional study was conducted in which 7800 subjects were sampled from two rural and one urban location. Visual Acuity was assessed and eye examination were performed by trained personnel. A questionnaire was used to collect personal and demographic information, and history of cataract surgery. Blindness and moderate Visual Impairment (MVI) was defined as presenting VA blindness was seen in 14.7% of the eyes. A significantly higher proportion of subjects in urban area had good outcome as compared to those in the rural area (p = 0.01). Uncorrected refractive error (58.7%) was the leading cause of MVI, and posterior segment disease (34.3%) was the leading cause of blindness. On applying multiple logistic regression, risk factors for poor outcomes were age ≥ 70 years (OR: 1.9, 95% CI: 1.3-2.8), rural residence (OR: 1.3, 95% CI:1.0-1.8) and presence of aphakia (OR: 8.9, 95% CI: 5.7-13.8). Post cataract surgery, refractive errors remain an important correctable cause of MVI, in the south Indian state of Andhra Pradesh. The correction of refractive errors is required to provide good visual recovery and achieve the benefit of cataract surgery.

  20. Validity of Race, Ethnicity, and National Origin in Population-based Cancer Registries and Rapid Case Ascertainment Enhanced With a Spanish Surname List.

    Science.gov (United States)

    Clarke, Lisa C; Rull, Rudolph P; Ayanian, John Z; Boer, Robert; Deapen, Dennis; West, Dee W; Kahn, Katherine L

    2016-01-01

    Accurate information regarding race, ethnicity, and national origins is critical for identifying disparities in the cancer burden. To examine the use of a Spanish surname list to improve the quality of race-related information obtained from rapid case ascertainment (RCA) and to estimate the accuracy of race-related information obtained from cancer registry records collected by routine reporting. Self-reported survey responses of 3954 participants from California enrolled in the Cancer Care Outcomes Research and Surveillance Consortium. Sensitivity, specificity, positive predictive value, and percent agreement. We used logistic regression to identify predictors of underreporting and overreporting of a race/ethnicity. Use of the Spanish surname list increased the sensitivity of RCA for Latino ethnicity from 37% to 83%. Sensitivity for cancer registry records collected by routine reporting was ≥95% for whites, blacks, and Asians, and specificity was high for all groups (86%-100%). However, patterns of misclassification by race/ethnicity were found that could lead to biased cancer statistics for specific race/ethnicities. Discordance between self-reported and registry-reported race/ethnicity was more likely for women, Latinos, and Asians. Methods to improve race and ethnicity data, such as using Spanish surnames in RCA and instituting data collection guidelines for hospitals, are needed to ensure minorities are accurately represented in clinical and epidemiological research.

  1. Rapid assessment of sexually transmitted diseases in a sentinel population in Thailand: prevalence of chlamydial infection, gonorrhoea, and syphilis among pregnant women--1996.

    Science.gov (United States)

    Kilmarx, P H; Black, C M; Limpakarnjanarat, K; Shaffer, N; Yanpaisarn, S; Chaisilwattana, P; Siriwasin, W; Young, N L; Farshy, C E; Mastro, T D; St Louis, M E

    1998-06-01

    To determine the prevalence of sexually transmitted diseases (STDs) among pregnant women in Thailand, where case reporting suggests a marked decrease in STDs following a campaign promoting condom use during commercial sex. Cross sectional study of women at their first visit to the study hospitals' antenatal clinics in Chiang Rai (n = 500) and Bangkok (n = 521). First catch urine specimens were tested for Chlamydia trachomatis and Neisseria gonorrhoeae using the Amplicor CT/NG polymerase chain reaction assay. Syphilis and HIV serological testing were performed in the study hospitals' laboratories. The prevalence of chlamydial infection was 5.7%, gonorrhoea 0.2%, and syphilis 0.5% (all VDRL or RPR titres were gestational age at first antenatal clinic visit, but was not associated with marital status, gravidity, city of enrollment, or HIV infection status. There was a low prevalence of gonorrhoea and syphilis among these pregnant women in Thailand. Chlamydial infection was detected at a higher prevalence, especially among younger women and women registering later for antenatal care. Testing of pregnant women using easily collected urine specimens and a sensitive nucleic acid amplification assay is a feasible method of rapidly assessing chlamydial and gonococcal prevalence.

  2. Mechanisms in intracellular turnover of stable and labile enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Kenney, F. T.; Pomato, N.; Lee, K. L.

    1977-01-01

    We have focused on two proteins of rat liver, one representative of the stable class and probably of reaction mechanisms operative in degradation of all proteins, the other unusually labile and possibly subject to uncommon as well as common mechanisms in turnover. The proteins chosen, tyrosine aminotransferase (E.C. 2.6.1.5) and alanine aminotransferase (E.C. 2.6.1.2) are similar in many respects. They catalyze similar reactions and share a substrate pair (glutamic acid and ..cap alpha..-ketoglutarate). Both are located in the soluble fraction of liver cytoplasm. Molecular weights are comparable (tyrosine aminotransferase, 100,000; alanine aminotransferase, 115,000) and both enzymes are structurally dimers of apparently identical subunits each of which binds one molecule of the common coenzyme, pyridoxal phosphate. Metabolically both are inducible by glucocorticoid hormones. But there the resemblance ends, for on the other, degradative side of the metabolic coin the two enzymes are sharply divergent. Tyrosine aminotransferase is among the most labile of liver enzymes, undergoing turnover with a half-life of 1.5 h, while turnover of alanine aminotransferase (half-life about 3 days) is virtually identical to that of the bulk of soluble liver proteins. Recent experimentation designed to determine the mechanistic basis for this difference in metabolism of otherwise quite similar enzymes is reviewed.

  3. Bone turnover markers in epileptic patients under chronic valproate therapy

    Directory of Open Access Journals (Sweden)

    Mohammad Zare

    2013-01-01

    Full Text Available Background: The effects of chronic valproic acid administration on bone health have been a matter of concern and controversy. In this study, the bone status following valproate intake was assessed by using several bone-related biochemical markers. Materials and Methods: In this case-control study, 62 epileptic patients and 40 age- and gender-matched controls were enrolled. The patients had been under chronic valproate therapy (758 ± 29 mg/day for at least the past 6 months, without any vitamin D/or calcium supplementation. Serum markers of bone turnover (carboxy-terminal telopeptide of type I collagen (CTX and bone-specific alkaline phosphatase [BALP], calcium, phosphorus, total alkaline phosphatase, and parathyroid hormone levels were measured in both groups. Results: The markers of bone turnover as well as other measured bone biochemical parameters did not statistically differ between the two groups. Conclusion: Valproate therapy at the mentioned doses does not seem to change bone turnover in adult epileptic patients.

  4. KEAHLIAN AUDITOR DAN TURNOVER INTENTION SEBAGAI MEDIASI DETERMINAN KINERJA AUDITOR

    Directory of Open Access Journals (Sweden)

    Ceacilia Srimindarti

    2015-12-01

    Full Text Available This research aims to examine the effect of locus of control and organizational commitment on auditors’ performance as well as to examine whether auditors’ expertise and turnover intention mediate the effect of locus of control and organizational commitment on auditors’ performance. Samples of this study were auditors who worked at audit firms in Semarang. Samples were selected using the purposive sampling method. The data were analyzed using SEM with AMOS program. This study found that locus of control had a negative effect on auditors’ performance, organizational commitment had a positive effect on auditors’ performance, and auditors’ expertise and turnover intention had no effect on auditors’ performance. Furthermore, locus of control had a negative effect on auditors’ expertise, and organizational commitment had a negative effect on turnover intention. Based on this result, managers of public accounting firm (partners should provide some trainings to the auditors who had the external locus of control so that they can achieve the standardized performances. They should also confirm the company’s values to the auditor to increase emotional attachment to the company as well as try to comply to the demands of the company thus its performance will be in accordance with company’s expectations.

  5. New Insights into the Protein Turnover Regulation in Ethylene Biosynthesis.

    Science.gov (United States)

    Yoon, Gyeong Mee

    2015-07-01

    Biosynthesis of the phytohormone ethylene is under tight regulation to satisfy the need for appropriate levels of ethylene in plants in response to exogenous and endogenous stimuli. The enzyme 1-aminocyclopropane-1-carboxylic acid synthase (ACS), which catalyzes the rate-limiting step of ethylene biosynthesis, plays a central role to regulate ethylene production through changes in ACS gene expression levels and the activity of the enzyme. Together with molecular genetic studies suggesting the roles of post-translational modification of the ACS, newly emerging evidence strongly suggests that the regulation of ACS protein stability is an alternative mechanism that controls ethylene production, in addition to the transcriptional regulation of ACS genes. In this review, recent new insight into the regulation of ACS protein turnover is highlighted, with a special focus on the roles of phosphorylation, ubiquitination, and novel components that regulate the turnover of ACS proteins. The prospect of cross-talk between ethylene biosynthesis and other signaling pathways to control turnover of the ACS protein is also considered.

  6. Examining the temporal relationship between psychological climate, work attitude, and staff turnover.

    Science.gov (United States)

    Garner, Bryan R; Hunter, Brooke D

    2013-02-01

    Relative to the broader industrial-organizational (I-O) psychology field, research on the turnover of substance use disorder (SUD) treatment staff is in its infancy. Despite its long and rich history, recent reviews of the turnover literature within I-O psychology have noted that there remains considerable room for improvement. In particular, recommendations have been made for research that considers time in the turnover process and explores more distal causes of staff turnover. Addressing these gaps, this article examined the temporal relationship between latent measures of psychological climate, work attitude, and staff turnover. Using data from 95 SUD treatment staff clustered within 29 treatment organizations, multilevel discrete-time survival analyses revealed that a latent measure of work attitude (e.g., job satisfaction, pay satisfaction, turnover intentions) fully mediated the temporal relationship between latent measures of psychological climate (e.g., supervisor support, coworker support, role conflict) and subsequent staff turnover. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Rapid Prototyping

    Science.gov (United States)

    1999-01-01

    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  8. Scalable metagenomics alignment research tool (SMART): a scalable, rapid, and complete search heuristic for the classification of metagenomic sequences from complex sequence populations.

    Science.gov (United States)

    Lee, Aaron Y; Lee, Cecilia S; Van Gelder, Russell N

    2016-07-28

    Next generation sequencing technology has enabled characterization of metagenomics through massively parallel genomic DNA sequencing. The complexity and diversity of environmental samples such as the human gut microflora, combined with the sustained exponential growth in sequencing capacity, has led to the challenge of identifying microbial organisms by DNA sequence. We sought to validate a Scalable Metagenomics Alignment Research Tool (SMART), a novel searching heuristic for shotgun metagenomics sequencing results. After retrieving all genomic DNA sequences from the NCBI GenBank, over 1 × 10(11) base pairs of 3.3 × 10(6) sequences from 9.25 × 10(5) species were indexed using 4 base pair hashtable shards. A MapReduce searching strategy was used to distribute the search workload in a computing cluster environment. In addition, a one base pair permutation algorithm was used to account for single nucleotide polymorphisms and sequencing errors. Simulated datasets used to evaluate Kraken, a similar metagenomics classification tool, were used to measure and compare precision and accuracy. Finally using a same set of training sequences we compared Kraken, CLARK, and SMART within the same computing environment. Utilizing 12 computational nodes, we completed the classification of all datasets in under 10 min each using exact matching with an average throughput of over 1.95 × 10(6) reads classified per minute. With permutation matching, we achieved sensitivity greater than 83 % and precision greater than 94 % with simulated datasets at the species classification level. We demonstrated the application of this technique applied to conjunctival and gut microbiome metagenomics sequencing results. In our head to head comparison, SMART and CLARK had similar accuracy gains over Kraken at the species classification level, but SMART required approximately half the amount of RAM of CLARK. SMART is the first scalable, efficient, and rapid metagenomics classification algorithm

  9. Rapid and inexpensive detection of common HBB gene mutations in Tunisian population by high-resolution melting analysis: implication for molecular diagnosis.

    Science.gov (United States)

    Ouragini, Houyem; Haddad, Faten; Darragi, Imen; Abbes, Salem

    2014-03-01

    In Tunisia, β-thalassemia is a common hereditary disease with a carrying rate of 2.21%. Up to now, detection of responsible mutations was made by laborious, expensive, and/or time consuming methods. The aim of this study is to develop and validate a specific assay for detection of the two most frequent mutations in Tunisian population, the IVS-I-110 (G → A) and Cd39 (C → T) mutations. In this study, we optimize high resolution melting analysis (HRMA) conditions for these mutations, using control DNAs. Then, we evaluate the strength of this methodology by screening a cohort of patients with β-thalassemia. All examined reference DNA samples were unambiguously distinguished from each other. For the blinded test, the results were completely compatible with direct sequencing, performed after the HRMA. As HRMA represents a highly sensitive and high-throughput gene scanning method, it can provide timely diagnosis at low cost for effective clinical management of β-thalassemia.

  10. Eating habits of a population undergoing a rapid dietary transition: portion sizes of traditional and non-traditional foods and beverages consumed by Inuit adults in Nunavut, Canada.

    Science.gov (United States)

    Sheehy, Tony; Roache, Cindy; Sharma, Sangita

    2013-06-02

    To determine the portion sizes of traditional and non-traditional foods being consumed by Inuit adults in three remote communities in Nunavut, Canada. A cross-sectional study was carried out between June and October, 2008. Trained field workers collected dietary data using a culturally appropriate, validated quantitative food frequency questionnaire (QFFQ) developed specifically for the study population. Caribou, muktuk (whale blubber and skin) and Arctic char (salmon family), were the most commonly consumed traditional foods; mean portion sizes for traditional foods ranged from 10 g for fermented seal fat to 424 g for fried caribou. Fried bannock and white bread were consumed by >85% of participants; mean portion sizes for these foods were 189 g and 70 g, respectively. Sugar-sweetened beverages and energy-dense, nutrient-poor foods were also widely consumed. Mean portion sizes for regular pop and sweetened juices with added sugar were 663 g and 572 g, respectively. Mean portion sizes for potato chips, pilot biscuits, cakes, chocolate and cookies were 59 g, 59 g, 106 g, 59 g, and 46 g, respectively. The present study provides further evidence of the nutrition transition that is occurring among Inuit in the Canadian Arctic. It also highlights a number of foods and beverages that could be targeted in future nutritional intervention programs aimed at obesity and diet-related chronic disease prevention in these and other Inuit communities.

  11. Did sex chromosome turnover promote divergence of the major mammal groups?

    Science.gov (United States)

    2016-01-01

    Comparative mapping and sequencing show that turnover of sex determining genes and chromosomes, and sex chromosome rearrangements, accompany speciation in many vertebrates. Here I review the evidence and propose that the evolution of therian mammals was precipitated by evolution of the male‐determining SRY gene, defining a novel XY sex chromosome pair, and interposing a reproductive barrier with the ancestral population of synapsid reptiles 190 million years ago (MYA). Divergence was reinforced by multiple translocations in monotreme sex chromosomes, the first of which supplied a novel sex determining gene. A sex chromosome‐autosome fusion may have separated eutherians (placental mammals) from marsupials 160 MYA. Another burst of sex chromosome change and speciation is occurring in rodents, precipitated by the degradation of the Y. And although primates have a more stable Y chromosome, it may be just a matter of time before the same fate overtakes our own lineage. Also watch the video abstract. PMID:27334831

  12. Turnover, account value and diversification of real traders: evidence of collective portfolio optimizing behavior

    Science.gov (United States)

    Morton de Lachapelle, David; Challet, Damien

    2010-07-01

    Despite the availability of very detailed data on financial markets, agent-based modeling is hindered by the lack of information about real trader behavior. This makes it impossible to validate agent-based models, which are thus reverse-engineering attempts. This work is a contribution towards building a set of stylized facts about the traders themselves. Using the client database of Swissquote Bank SA, the largest online Swiss broker, we find empirical relationships between turnover, account values and the number of assets in which a trader is invested. A theory based on simple mean-variance portfolio optimization that crucially includes variable transaction costs is able to reproduce faithfully the observed behaviors. We finally argue that our results bring to light the collective ability of a population to construct a mean-variance portfolio that takes into account the structure of transaction costs.

  13. Rapid species identification of "Streptococcus milleri" strains by line blot hybridization: identification of a distinct 16S rRNA population closely related to Streptococcus constellatus.

    Science.gov (United States)

    Jacobs, J A; Schot, C S; Bunschoten, A E; Schouls, L M

    1996-01-01

    A collection of 399 "Streptococcus milleri" strains were identified to the species level by the use of a line blot assay. Their PCR-amplified partial 16S rRNA gene sequences were hybridized with species-specific 5'-biotinylated oligonucleotide probes homologous to the bp 213 to 231 regions of the 16S rRNA gene sequences of the type strains Streptococcus anginosus ATCC 33397, Streptococcus constellatus ATCC 27823, and Streptococcus intermedius ATCC 27335. The hybridization results were compared with the reference phenotypic identification method data (R. A. Whiley, H. Fraser, J. M. Hardie, and D. Beighton, J. Clin. Microbiol. 28:1497-1501, 1990). Most strains (357 of 399 [89.5%]) reacted unambiguously with only one probe. However, 42 of the 399 strains (10.5%) reacted with both the S. constellatus- and S. intermedius-specific probes; 41 of them were phenotypically identified as S. constellatus. These dually reactive strains hybridized with a 5'-biotinylated probe based on the bp 213 to 231 region of the 16S rRNA gene sequence of one of two species. Analysis of the 5' ends of the 16S rRNA gene sequences (487 bp) demonstrated that the dually reactive strains represent a distinct rRNA population sharing 98.1% sequence similarity with S. constellatus. Phenotypic consistency between the dually reactive strains and the S. constellatus strains was not demonstrated. Line blot hybridization proved to be a simple and inexpensive method to screen large numbers of strains for genetic relatedness, and it allowed the detection of a distinct 16S rRNA type within the "S. milleri" group. PMID:8784576

  14. Eating habits of a population undergoing a rapid dietary transition: portion sizes of traditional and non-traditional foods and beverages consumed by Inuit adults in Nunavut, Canada

    Science.gov (United States)

    2013-01-01

    Background To determine the portion sizes of traditional and non-traditional foods being consumed by Inuit adults in three remote communities in Nunavut, Canada. Methods A cross-sectional study was carried out between June and October, 2008. Trained field workers collected dietary data using a culturally appropriate, validated quantitative food frequency questionnaire (QFFQ) developed specifically for the study population. Results Caribou, muktuk (whale blubber and skin) and Arctic char (salmon family), were the most commonly consumed traditional foods; mean portion sizes for traditional foods ranged from 10 g for fermented seal fat to 424 g for fried caribou. Fried bannock and white bread were consumed by >85% of participants; mean portion sizes for these foods were 189 g and 70 g, respectively. Sugar-sweetened beverages and energy-dense, nutrient-poor foods were also widely consumed. Mean portion sizes for regular pop and sweetened juices with added sugar were 663 g and 572 g, respectively. Mean portion sizes for potato chips, pilot biscuits, cakes, chocolate and cookies were 59 g, 59 g, 106 g, 59 g, and 46 g, respectively. Conclusions The present study provides further evidence of the nutrition transition that is occurring among Inuit in the Canadian Arctic. It also highlights a number of foods and beverages that could be targeted in future nutritional intervention programs aimed at obesity and diet-related chronic disease prevention in these and other Inuit communities. PMID:23724920

  15. Distribution and turnover of carbon in natural and constructed wetlands in the Florida Everglades

    Energy Technology Data Exchange (ETDEWEB)

    Stern, J. [Department of Geological Sciences, Florida State University and National High Magnetic Field Laboratory, Tallahassee, FL 32306-4100 (United States); NASA Ames Research Center, Moffett Field, CA 94035 (United States); Wang, Y. [Department of Geological Sciences, Florida State University and National High Magnetic Field Laboratory, Tallahassee, FL 32306-4100 (United States)], E-mail: ywang@magnet.fsu.edu; Gu, B.; Newman, J. [Everglades Division, South Florida Water Management District, West Palm Beach, FL 33406 (United States)

    2007-09-15

    Stable and radiocarbon isotopic contents of dissolved organic C (DOC), dissolved inorganic C (DIC), particulate organic C (POC) and plants were used to examine the source and turnover rate of C in natural and constructed wetlands in the Florida Everglades. DOC concentrations decreased, with P concentrations, along a water quality gradient from the agriculturally impacted areas in the northern Everglades to the more pristine Everglades National Park. {delta}{sup 13}C values of DOC in the area reflect contributions of both wetland vegetation and sugarcane from agriculture. Radiocarbon ages of DOC, POC and DIC in the Everglades ranged from 2.01 ka BP to '>modern'. The old {sup 14}C ages of DOC and POC were found in impacted areas near the Everglades Agricultural Area (EAA) in the northern Everglades. In contrast, DOC and POC in pristine marsh areas had near modern or '>modern'{sup 14}C ages. These data indicate that a major source of POC and DOC in impacted areas is the degradation of historic peat deposits in the EAA. In the pristine areas of the marsh, DOC represents a mix of modern and historic C sources, whereas POC comes from modern primary production as indicated by positive {delta}{sup 14}C values, suggesting that DOC is transported farther away from its source than POC. High {delta}{sup 14}C values of DIC indicate that dissolution of limestone bedrock is not a significant source of DIC in the Everglades wetlands. As a restored wetland moves towards its 'original' or 'natural' state, the {sup 14}C signatures of DOC should approach that of modern atmosphere. In addition, measurements of concentration and C isotopic composition of DOC in two small constructed wetlands (i.e., test cells) indicate that these freshwater wetland systems contain a labile DOC pool with rapid turnover times of 26-39 days and that the test cells are overall net sinks of DOC.

  16. Benthic nitrogen turnover processes in coastal sediments at the Danube Delta

    Science.gov (United States)

    Bratek, Alexander; Dähnke, Kirstin; Neumann, Andreas; Möbius, Jürgen; Graff, Florian

    2017-04-01

    The Black Sea Shelf has been exposed to strong anthropogenic pressures from intense fisheries and high nutrient inputs and eutrophication over the past decades. In the light of decreasing riverine nutrient loads and improving nutrient status in the water column, nutrient regeneration in sediments and biological N-turnover in the Danube Delta Front have an important effect on nutrient loads in the shelf region. In May 2016 we determined pore water nutrient profiles in the Danube River Delta-Black Sea transition zone, aiming to assess N-regeneration and elimination based on nutrient profiles and stable N- isotope changes (nitrate and ammonium) in surface water masses and in pore water. We aimed to investigate the magnitude and isotope values of sedimentary NH4+ and NO3- and their impact on the current N-budget in Black Sea Shelf water. Based on changes in the stable isotope ratios of NO3- and NH4+, we aimed to differentiate diffusion and active processing of ammonium as well as nitrate sources and sinks in bottom water. First results show that the concentration of NH4+ in pore water increases with depth, reaching up to 1500 µM in deeper sediment layers. We find indications for high fluxes of ammonium to the overlying water, while stable isotope profiles of ammonium suggest that further processing, apart from mere diffusion, acts on the pore water ammonium pool. Nitrate concentration and stable isotope profiles show rapid consumption in deeper anoxic sediment layers, but also suggest that nitrate regeneration in bottom water increases the dissolved nitrate pool. Overall, the isotope and concentration data of pore water ammonium clearly mirror a combination of turnover processes and diffusion.

  17. Methane turnover and environmental change from Holocene biomarker records in a thermokarst lake in Arctic Alaska

    Science.gov (United States)

    Elvert, Marcus; Pohlman, John; Becker, Kevin W.; Gaglioti, Benjamin V.; Hinrichs, Kai-Uwe; Wooller, Matthew J.

    2016-01-01

    Arctic lakes and wetlands contribute a substantial amount of methane to the contemporary atmosphere, yet profound knowledge gaps remain regarding the intensity and climatic control of past methane emissions from this source. In this study, we reconstruct methane turnover and environmental conditions, including estimates of mean annual and summer temperature, from a thermokarst lake (Lake Qalluuraq) on the Arctic Coastal Plain of northern Alaska for the Holocene by using source-specific lipid biomarkers preserved in a radiocarbon-dated sediment core. Our results document a more prominent role for methane in the carbon cycle when the lake basin was an emergent fen habitat between ~12,300 and ~10,000 cal yr BP, a time period closely coinciding with the Holocene Thermal Maximum (HTM) in North Alaska. Enhanced methane turnover was stimulated by relatively warm temperatures, increased moisture, nutrient supply, and primary productivity. After ~10,000 cal yr BP, a thermokarst lake with abundant submerged mosses evolved, and through the mid-Holocene temperatures were approximately 3°C cooler. Under these conditions, organic matter decomposition was attenuated, which facilitated the accumulation of submerged mosses within a shallower Lake Qalluuraq. Reduced methane assimilation into biomass during the mid-Holocene suggests that thermokarst lakes are carbon sinks during cold periods. In the late-Holocene from ~2700 cal yr BP to the most recent time, however, temperatures and carbon deposition rose and methane oxidation intensified, indicating that more rapid organic matter decomposition and enhanced methane production could amplify climate feedback via potential methane emissions in the future.

  18. Isotopic discrimination factors and nitrogen turnover rates in reared Atlantic bluefin tuna larvae (Thunnus thynnus: effects of maternal transmission

    Directory of Open Access Journals (Sweden)

    Amaya Uriarte

    2016-11-01

    Full Text Available The use of stable isotope analysis to study animal diets requires estimates of isotopic turnover rates (half time, t50 and discrimination factors (Δ for an accurate interpretation of trophic patterns. The stable isotopes of carbon and nitrogen were analysed for eggs and reared larvae of Thunnus thynnus, as well as for the different diets supplied during the experiment. The results showed high values of δ15N in eggs and larvae (n=646 until 4 DAH. After this time lapse, the stable isotope values declined progressively until 12 DAH, when notochord flexion began. The δ13C showed an inverse trend, suggesting that maternal inheritance of the stable isotopes is evident until pre-flexion stages. This study proposes a model for estimating maternal isotopic signatures of bluefin broodstock. After notochord flexion, larvae were fed with aquaculture-bred gilthead seabream, which resulted in a rapid increase of bluefin larvae δ15N values together with a rapid decrease in δ13C values. The estimated nitrogen half-time to reach the steady state from the diet was 2.5±0.3 days and the discrimination factor was 0.4±0.3(‰. These results represent the first data set that has allowed isotopic nitrogen turnover rates and discrimination factors of the larval stages of bluefin tuna to be estimated.

  19. Age-period-cohort projections of ischaemic heart disease mortality by socio-economic position in a rapidly transitioning Chinese population.

    Directory of Open Access Journals (Sweden)

    Irene O L Wong

    Full Text Available BACKGROUND: With economic development and population aging, ischaemic heart disease (IHD is becoming a leading cause of mortality with widening inequalities in China. To forewarn the trends in China we projected IHD trends in the most economically developed part of China, i.e., Hong Kong. METHODS: Based on sex-specific IHD mortality rates from 1976 to 2005, we projected mortality rates by neighborhood-level socio-economic position (i.e., low- or high-income groups to 2020 in Hong Kong using Poisson age-period-cohort models with autoregressive priors. RESULTS: In the low-income group, age-standardized IHD mortality rates among women declined from 33.3 deaths in 1976-1980 to 19.7 per 100,000 in 2016-2020 (from 55.5 deaths to 34.2 per 100,000 among men. The rates in the high-income group were initially higher in both sexes, particularly among men, but this had reversed by the end of the study periods. The rates declined faster for the high-income group than for the low-income group in both sexes. The rates were projected to decline faster in the high-income group, such that by the end of the projection period the high-income group would have lower IHD mortality rates, particularly for women. Birth cohort effects varied with sex, with a marked upturn in IHD mortality around 1945, i.e., for the first generation of men to grow up in a more economically developed environment. There was no such upturn in women. Birth cohort effects were the main drivers of change in IHD mortality rates. CONCLUSION: IHD mortality rates are declining in Hong Kong and are projected to continue to do so, even taking into account greater vulnerability for the first generation of men born into a more developed environment. At the same time social disparities in IHD have reversed and are widening, partly as a result of a cohort effect, with corresponding implications for prevention.

  20. Fluorescence single-molecule imaging of actin turnover and regulatory mechanisms.

    Science.gov (United States)

    Watanabe, Naoki

    2012-01-01

    Cells must rapidly remodel the actin filament network to achieve various cellular functions. Actin filament turnover is a dynamic process that plays crucial roles in cell adhesion, locomotion, cytokinesis, endocytosis, phagocytosis, tissue remodeling, etc., and is regulated by cell signaling cascades. Success in elucidating dynamic biological processes such as actin-based motility relies on the means enabling real time monitoring of the process. The invention of live-cell fluorescence single-molecule imaging has opened a window for direct viewing of various actin remodeling processes. In general, assembly and dissociation of actin and its regulators turned out to occur at the faster rates than previously estimated by biochemical and structural analyses. Cells undergo such fast continuous exchange of the components perhaps not only to drive actin remodeling but also to facilitate rapid response in many other cell mechanics and signaling cascades. This chapter describes how epifluorescence single-molecule imaging which visualizes deeper area than the TIRF microscopy is achieved in XTC cells, the currently best platform for this approach. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Serum concentration of biochemical bone turnover markers in vegetarian children.

    Science.gov (United States)

    Ambroszkiewicz, J; Klemarczyk, W; Gajewska, J; Chełchowska, M; Laskowska-Klita, T

    2007-01-01

    In general, most children on well-planed vegetarian diets can achieve normal growth and development. However, elimination of animal products from the diet decreases the intake of some essential nutrients, such as calcium and vitamin D, and may influence bone metabolism. This is especially important in childhood and adolescence, when growth and bone turnover are most intensive. The aim of this study was to investigate the serum concentrations of biochemical bone turnover markers in prepubertal vegetarian children. We examined 50 children on vegetarian and 50 on omnivorous diets aged 2-10 years. Dietary constituents were analyzed using a local nutritional program. Serum bone formation (OC, BALP) and resorption (CTX) markers were determined by specific enzyme immunoassays (ELISA) and 25-hydroxyvitamin D by the chemiluminescence method (CLIA). The average daily energetic value and the percentage of energy from protein, fat and carbohydrates in the diets were similar in both groups of children and were within the recommended range. The vegetarian children showed about a two-fold lower daily intake of calcium and vitamin D than their omnivorous counterparts. The level of 25-hydroxyvitamin D in the serum of vegetarian children was also nearly 2-fold lower compared with omnivores. In vegetarians, as compared to non-vegetarians, mean serum concentrations of OC, BALP and CTX were lower by about 20%, 10% and 15%, respectively. Our preliminary results suggest that an inadequate dietary intake of calcium and vitamin D may impair bone turnover rate in vegetarian children. The parameters of bone metabolism should be monitored in these children in order to prevent bone abnormalities.

  2. Fat Cell and Fatty Acid Turnover in Obesity.

    Science.gov (United States)

    Engin, Atilla

    2017-01-01

    The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. Inhibition of adipose triglyceride lipase leads to an accumulation of triglyceride, whereas inhibition of hormone-sensitive lipase leads to the accumulation of diacylglycerol. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride turnover. Excess triacylglycerols (TAGs), sterols and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets. Following the release of lipid droplets from endoplasmic reticulum, cytoplasmic lipid droplets increase their volume either by local TAG synthesis or by homotypic fusion. The number and the size of lipid droplet distribution is correlated with obesity. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. NOD-like receptors family pyrin domain containing 3 (NLRP3) inflammasome-dependent caspase-1 activation in hypertrophic adipocytes induces obese adipocyte death by pyroptosis. Actually adipocyte death may be a prerequisite for the transition from hypertrophic to hyperplastic obesity. Major transcriptional factors, CCAAT/enhancer-binding proteins beta and delta, play a central role in the subsequent induction of critical regulators, peroxisome-proliferator-activated receptor gamma, CCAAT/enhancer-binding protein alpha and sterol regulatory element-binding protein 1, in the transcriptional control of adipogenesis in obesity.Collectively, in this chapter the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of lipid droplet interactions with the other cellular organelles are reviewed. Furthermore, in addition to lipid droplet growth, the functional link between the adipocyte-specific lipid

  3. Growth rate correlates negatively with protein turnover in Arabidopsis accessions.

    Science.gov (United States)

    Ishihara, Hirofumi; Moraes, Thiago Alexandre; Pyl, Eva-Theresa; Schulze, Waltraud X; Obata, Toshihiro; Scheffel, André; Fernie, Alisdair R; Sulpice, Ronan; Stitt, Mark

    2017-08-01

    Previous studies with Arabidopsis accessions revealed that biomass correlates negatively to dusk starch content and total protein, and positively to the maximum activities of enzymes in photosynthesis. We hypothesized that large accessions have lower ribosome abundance and lower rates of protein synthesis, and that this is compensated by lower rates of protein degradation. This would increase growth efficiency and allow more investment in photosynthetic machinery. We analysed ribosome abundance and polysome loading in 19 accessions, modelled the rates of protein synthesis and compared them with the observed rate of growth. Large accessions contained less ribosomes than small accessions, due mainly to cytosolic ribosome abundance falling at night in large accessions. The modelled rates of protein synthesis resembled those required for growth in large accessions, but were up to 30% in excess in small accessions. We then employed 13 CO2 pulse-chase labelling to measure the rates of protein synthesis and degradation in 13 accessions. Small accessions had a slightly higher rate of protein synthesis and much higher rates of protein degradation than large accessions. Protein turnover was negligible in large accessions but equivalent to up to 30% of synthesised protein day-1 in small accessions. We discuss to what extent the decrease in growth in small accessions can be quantitatively explained by known costs of protein turnover and what factors may lead to the altered diurnal dynamics and increase of ribosome abundance in small accessions, and propose that there is a trade-off between protein turnover and maximisation of growth rate. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  4. Centennial black carbon turnover observed in a Russia steppe soil

    Energy Technology Data Exchange (ETDEWEB)

    Hammes, K.; Torn, M.S.; Lapenas, A.G.; Schmidt, M.W.I.

    2008-09-15

    Black carbon (BC), from incomplete combustion of fuels and biomass, has been considered highly recalcitrant and a substantial sink for carbon dioxide. Recent studies have shown that BC can be degraded in soils. We use two soils with very low spatial variability sampled 100 years apart in a Russian steppe preserve to generate the first whole-profile estimate of BC stocks and turnover in the field. Quantities of fire residues in soil changed significantly over a century. Black carbon stock was 2.5 kg m{sup -2}, or about 7-10% of total organic C in 1900. With cessation of biomass burning, BC stocks decreased 25% over a century, which translates into a centennial soil BC turnover (293 years best estimate; range 182-541 years), much faster than so-called inert or passive carbon in ecosystem models. The turnover time presented here is for loss by all processes, namely decomposition, leaching, and erosion, although the latter two were probably insignificant in this case. Notably, at both time points, the peak BC stock was below 30 cm, a depth interval, which is not typically accounted for. Also, the quality of the fire residues changed with time, as indicated by the use benzene poly carboxylic acids (BPCA) as molecular markers. The proportions of less-condensed (and thus more easily degradable) BC structures decreased, whereas the highly condensed (and more recalcitrant) BC structures survived unchanged over the 100-year period. Our results show that BC cannot be assumed chemically recalcitrant in all soils, and other explanations for very old soil carbon are needed.

  5. Bone Turnover in Postmenopausal Women with Bone Loss - Original Investigation

    Directory of Open Access Journals (Sweden)

    Nurdan Paker

    2005-12-01

    Full Text Available Osteoporosis is characterized by decrease in bone strength due to decreased bone mass and disruption of bone microstructure and eventually increase in fracture risk. Increased bone turnover in postmenopausal period results in bone loss and osteoporosis. Aim of our study was to investigate the rate of bone turnover in postmenopausal women. Postmenopausal women were included in this study. Dual energy X ray absorbtiometry( Dexa was used for the measurement of BMD of the lumbar spine and proximal femur. Serum osteocalcin and type 1 collagen cross-linked C-telopeptide (Ctx levels were measured in blood. 32 postmenopausal women with bone loss were included in our study. The mean age was 61,5 ± 9,6 years, mean menopause duration 14,7± 9,5 years. The mean value of L2- L4 BMD was 0,910 ±0,143 gr/cm2 , femur neck BMD 0,734± 0,134 gr/cm2. Mean blood osteocalcin level was 23,34± 10,9 ng/ml(normal range <20, Ctx level was 0,70± 0,27 (normal range <0.75 ng/ml. There was statistically significant negative relationship between the menopause duration and serum Ctx levels (R =0,382, p<0,05. Mean serum Ctx level was 0,83 ±0,11 ng/ml in the patients whose menopause duration was less than 5 years and was 0,7 ±0,3 ng/ml in the patients whose menopause duration was more than 5 years. There was no relationship between serum osteocalcin and Ctx levels with age, body mass index(BMI, menopause duration, L2- L4 and femur neck BMD values. There was statistically significant relation between BMI(body mass index and L2 - L4 and femur neck BMD values( p < 0.05. There was no relationship between regular walking activity with BMD, serum osteocalcin and Ctx levels. In this study increased bone turnover rate in early postmenopausal period has been shown. It was known that bone loss increases due to the estrogen deficiency in postmenopausal period. Therefore, bone turnover markers of postmenopausal women should be measured in addition to bone mineral density who had bone

  6. Influence of orlistat on bone turnover and body composition

    DEFF Research Database (Denmark)

    Gotfredsen, A; Westergren Hendel, H; Andersen, T

    2001-01-01

    OBJECTIVE: To investigate the influence of the pancreas lipase inhibitor orlistat (OLS) on calcium metabolism, bone turnover, bone mass, bone density and body composition when given for obesity as adjuvant to an energy- and fat-restricted diet. DESIGN: Randomized controlled double-blinded trial...... of treatment with OLS 120 mg three times daily or placebo for 1 y. SUBJECTS: Thirty obese subjects with a mean body mass index (BMI) of 36.9+/-3.7 kg/m(2) and a mean age of 41+/-11 y. Sixteen patients were assigned to OLS and 14 to placebo. MEASUREMENTS: Dual energy X-ray absorptiometry (DXA) measurements...

  7. High triacylglycerol turnover rate in human skeletal muscle

    DEFF Research Database (Denmark)

    Sacchetti, Massimo; Saltin, Bengt; Olsen, David B

    2004-01-01

    could be due to the observed decline in plasma insulin concentration (-74%, P skeletal muscle in post-absorptive healthy individuals is esterified into IMTAG, due to its high turnover rate (29 h pool(-1)). An increase in FA level...... into IMTAG in vastus lateralis muscle was determined during two consecutive 4-h periods (2-6 h and 6-10 h). Fifty to sixty per cent of the FA taken up from the circulation were esterified into IMTAG, whereas 32 and 42% were oxidized between 2-6 and 6-10 h, respectively. IMTAG fractional synthesis rate was 3...

  8. Clinical usefulness of bone turnover marker concentrations in osteoporosis

    DEFF Research Database (Denmark)

    Morris, H A; Eastell, R; Rye Jørgensen, Niklas

    2017-01-01

    Current evidence continues to support the potential for bone turnover markers (BTM) to provide clinically useful information particularly for monitoring the efficacy of osteoporosis treatment. Many of the limitations identified earlier remain, principally in regard to the relationship between BTM...... of combining such data for meta-analyses. Harmonization of units for reporting serum/plasma CTX (ng/L) and PINP (μg/L) is recommended. The development of international collaborations continues with an important initiative to combine BTM results from clinical trials in osteoporosis in a meta...

  9. Unsteady Flows Control Hydrologic Turnover Rates in Antarctic Hyporheic Zones

    Science.gov (United States)

    Wlostowski, A. N.; Gooseff, M. N.; McKnight, D. M.; Lyons, W. B.; Saelens, E.

    2016-12-01

    Hydrologic turnover of the hyporheic zone (HZ) is the process of HZ flowpaths receiving water and solutes from the stream channel while simultaneously contributing water and solutes from the HZ back to the stream channel. The influence of hydrologic turnover on HZ solute storage depends on the relative magnitude of hyporheic exchange rates (i.e. physical transport) and biogeochemical reaction rates. Because both exchange rates and reaction rates are unsteady in natural systems, the availability of solutes in the HZ is controlled by the legacy of hydraulic and biological conditions. In this study, we quantify the influence of unsteady flows on hydrologic turnover of the HZ. We study a glacial melt stream in the McMurdo Dry Valleys of Antarctica (MDVs). The MDVs provide an ideal setting for investigating hydrologic and chemical storage characteristics of HZs, because nearly all streamflow is generated from glacier melt and the HZ is vertically bounded by continuous permafrost. A dense network of shallow groundwater wells and piezometers was installed along a 60-meter reach of Von Guerard Stream. 12 days of continuous water level data in each well was used to compute the magnitude and direction of 2D hydraulic gradients between the stream channel and lateral hyporheic aquifer. Piezometers were sampled daily for stable isotope abundances. The direction and magnitude of the cross-valley (CV), perpendicular to the thalweg, component of hydraulic gradients is sensitive to daily flood events and exhibits significant spatial heterogeneity. CV gradients are consistently oriented from the hyporheic aquifer towards the stream channel on 2 sections of the study reach, whereas CV gradients are consistently oriented from the stream channel towards the hyporheic aquifer on 1 section. Three sections show diel changes in orientation of CV gradients, coincident with the passage of daily flood events. During a 4-day period of low flows, the HZ is isotopically distinct from the stream

  10. Bilateral Anterior Rectus Sheath Turnover Flap for Abdominal Closure

    Directory of Open Access Journals (Sweden)

    Bulent Kaya

    2013-10-01

    Full Text Available The management of abdominal wall hernias with tissue loss is a difficult subject.Several surgical techniques have been used in the treatment. Sometimes closure of the abdomen with primary sutures may be impossible. Dual meshes, component separation technique, usculofascial flaps can be used for closure of the abdomen.In this case report a patient with complex abdominal wall hernia was presented.The abdomen was successfully closed with anterior rectus sheath turnover flap.We discussed this surgical technique with literature review.

  11. Species turnover and geographic distance in an urban river network

    DEFF Research Database (Denmark)

    Rouquette, James R.; Dallimer, Martin; Armsworth, Paul R.

    2013-01-01

    of the habitat or topographic features of the landscape and the means of dispersal of the organism. River networks, in particular in human-modified landscapes, are a striking example of such a situation. Here, we use data for both aquatic and terrestrial organisms across an urban river network to examine...... patterns of species turnover and to determine whether these patterns differ between different taxonomic groups. LocationSheffield area, UK. MethodsAquatic (macroinvertebrates, diatoms) and terrestrial (birds, plants, butterflies) organisms were surveyed at 41 sites across an urban river network. We...

  12. Employee Turnover and Organizational Performance: a Study of the Brazilian Retail Sector

    Directory of Open Access Journals (Sweden)

    Luciana Carvalho de Mesquita Ferreira

    2015-01-01

    Full Text Available This study investigates the relationship between employee turnover and performance in retailing. To achieve this aim, we used data from a single company with several comparable branches and tested whether stores with lower employee turnover have better financial and organizational results (sales and workplace accidents, respectively. This study also analyzes whether Human resources practices, such as rewards, recognition and training, affect employee turnover. The empirical results indicate a strong relationship between employee turnover and sales, supporting results from previous studies. However, the additional relationships were not confirmed. The results do not rule out some hypotheses about the relationship between employee turnover and labor accidents, and further suggest that human resources management practices may increase employee turnover, depending on their motivation and strategic alignment.

  13. Transformational leadership moderates the relationship between emotional exhaustion and turnover intention among community mental health providers.

    Science.gov (United States)

    Green, Amy E; Miller, Elizabeth A; Aarons, Gregory A

    2013-08-01

    Public sector mental health care providers are at high risk for burnout and emotional exhaustion which negatively affect job performance and client satisfaction with services. Few studies have examined ways to reduce these associations, but transformational leadership may have a positive effect. We examine the relationships between transformational leadership, emotional exhaustion, and turnover intention in a sample of 388 community mental health providers. Emotional exhaustion was positively related to turnover intention, and transformational leadership was negatively related to both emotional exhaustion and turnover intention. Transformational leadership moderated the relationship between emotional exhaustion and turnover intention, indicating that having a transformational leader may buffer the effects of providers' emotional exhaustion on turnover intention. Investing in transformational leadership development for supervisors could reduce emotional exhaustion and turnover among public sector mental health providers.

  14. Transformational Leadership Moderates the Relationship between Emotional Exhaustion and Turnover Intention among Community Mental Health Providers

    Science.gov (United States)

    Green, Amy E.; Miller, Elizabeth A.; Aarons, Gregory A.

    2014-01-01

    Public sector mental health care providers are at high risk for burnout and emotional exhaustion which negatively affect job performance and client satisfaction with services. Few studies have examined ways to reduce these associations, but transformational leadership may have a positive effect. We examine the relationships between transformational leadership, emotional exhaustion, and turnover intention in a sample of 388 community mental health providers. Emotional exhaustion was positively related to turnover intention, and transformational leadership was negatively related to both emotional exhaustion and turnover intention. Transformational leadership moderated the relationship between emotional exhaustion and turnover intention, indicating that having a transformational leader may buffer the effects of providers’ emotional exhaustion on turnover intention. Investing in transformational leadership development for supervisors could reduce emotional exhaustion and turnover among public sector mental health providers. PMID:22052429

  15. Hospital Mergers in Norway: Employee Health and Turnover to Three Destinations

    Directory of Open Access Journals (Sweden)

    Mari Holm Ingelsrud

    2017-03-01

    Full Text Available This article investigates the probability of turnover to three destinations following hospital merg- ers: within the hospital sector, out of the hospital sector, and out of work. It is hypothesized that mergers increase turnover to nonemployment among employees with poor health and increase turnover to employment outside of the hospital sector among healthy employees. Discrete-time survival analyses show that mergers increase turnover within the hospital sector for all employ- ees, regardless of health. Turnover to other sectors and out of work does not increase. Possible explanations for the limited turnover out of the sector associated with mergers are aspects of the Norwegian labor market such as the institution of employee participation, low unemployment, and labor shortages within hospitals.

  16. Employee Turnover and Organizational Performance: a Study of the Brazilian Retail Sector

    OpenAIRE

    Luciana Carvalho de Mesquita Ferreira; Ciro Barbosa de Aquino Almeida

    2015-01-01

    This study investigates the relationship between employee turnover and performance in retailing. To achieve this aim, we used data from a single company with several comparable branches and tested whether stores with lower employee turnover have better financial and organizational results (sales and workplace accidents, respectively). This study also analyzes whether Human resources practices, such as rewards, recognition and training, affect employee turnover. The empirical results indic...

  17. Organizational Demography and Turnover: An Examination of Multiform and Non-Linear Heterogeneity

    OpenAIRE

    Alexander,Jeffrey; Nuchols, Beverly; Bloom, Joan; Lee, Shoou-Yih D

    1993-01-01

    This paper advances the study of organizational demography and its relationship to organizational turnover by examining two of Blau's concepts of social structure: non-linear and multiform heterogeneity. In a sample of 383 community hospitals, nursing turnover was examined in relation to four dimensions of demographic heterogeneity among nursing staff in those hospitals. The form of the relationships between turnover and heterogeneity was specified to test whether heterogeneity relates to hig...

  18. Factors Involved in Extracellular Matrix Turnover in Human Derived Cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Gregori Casals

    2013-11-01

    Full Text Available Background: The molecular mechanisms by which myocardial ischemia translates into ventricular remodeling remain unclear. Methods: We investigated whether hypoxia and proinflammatory cytokines are specific inducers of remodeling signals in an in vitro model of cultured adult human ventricular myocytes (AC16 cells. Results:Hypoxia modified the ratio of matrix remodeling factors by increasing the aminoterminal propeptide of type III procollagen (PIIINP and reducing tissue inhibitor of matrix metalloproteinase type 1 (TIMP-1 secretion in AC16 cells. These effects, however, were not associated with either modifications in expression of matrix metalloproteinase type 2, collagen-I or metalloproteinase activity. Hypoxia does, actually increase the production of the cardiac antifibrogenic growth factors, Apelin and VEGF, through an Hypoxia Inducible Factor type 1-dependent mechanism. Concerning proinflammatory signaling pathways, IL1β emerged as a powerful inducer of matrix turnover, since it significantly enhanced PIIINP, TIMP-1 and hyaluronic acid production and increased metalloproteinase activity. In contrast, TNFα did not modify matrix turnover but markedly induced the production of Apelin and VEGF. Conclusion: Hypoxia and increased TNFα activity likely exert cardioprotective actions by activating the cardiac antifibrogenic factors Apelin and VEGF. In contrast, IL1β is a strong promoter of interstitial collagen remodeling that may contribute to ventricular dilation and heart failure in the ischemic myocardium.

  19. Liquid Crystal Gel Reduces Age Spots by Promoting Skin Turnover

    Directory of Open Access Journals (Sweden)

    Mina Musashi

    2014-07-01

    Full Text Available Studies have shown that liquid crystals structurally resembling the intercellular lipids in the stratum corneum can beneficially affect the skin when applied topically by stimulating the skin’s natural regenerative functions and accelerating epidermal turnover. In the present study, the effects of applying low concentrations of a liquid crystal gel of our own creation were evaluated using epidermal thickening in mouse skin as an assay for effective stimulation of epidermal turnover. A liquid crystal gel was also applied topically to human facial skin, and analysis was conducted using before-and-after photographs of age spots, measurements of L* values that reflect degree of skin pigmentation, single-layer samples of the stratum corneum obtained via tape-stripping, and measurements of trans-epidermal water loss that reflect the status of the skin’s barrier function. The results suggested that cost-effective creams containing as low as 5% liquid crystal gel might be effective and safely sold as skin care products targeting age spots and other problems relating to uneven skin pigmentation.

  20. Blood Lead, Bone Turnover, and Survival in Amyotrophic Lateral Sclerosis.

    Science.gov (United States)

    Fang, Fang; Peters, Tracy L; Beard, John D; Umbach, David M; Keller, Jean; Mariosa, Daniela; Allen, Kelli D; Ye, Weimin; Sandler, Dale P; Schmidt, Silke; Kamel, Freya

    2017-11-01

    Blood lead and bone turnover may be associated with the risk of amyotrophic lateral sclerosis (ALS). We aimed to assess whether these factors were also associated with time from ALS diagnosis to death through a survival analysis of 145 ALS patients enrolled during 2007 in the National Registry of Veterans with ALS. Associations of survival time with blood lead and plasma biomarkers of bone resorption (C-terminal telopeptides of type I collagen (CTX)) and bone formation (procollagen type I amino-terminal peptide (PINP)) were estimated using Cox models adjusted for age at diagnosis, diagnostic certainty, diagnostic delay, site of onset, and score on the Revised ALS Functional Rating Scale. Hazard ratios were calculated for each doubling of biomarker concentration. Blood lead, plasma CTX, and plasma PINP were mutually adjusted for one another. Increased lead (hazard ratio (HR) = 1.38; 95% confidence interval (CI): 1.03, 1.84) and CTX (HR = 2.03; 95% CI: 1.42, 2.89) were both associated with shorter survival, whereas higher PINP was associated with longer survival (HR = 0.59; 95% CI: 0.42, 0.83), after ALS diagnosis. No interactions were observed between lead or bone turnover and other prognostic indicators. Lead toxicity and bone metabolism may be involved in ALS pathophysiology. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  1. How to reduce turnover by creating a positive work climate.

    Science.gov (United States)

    Kushell, R E

    1979-08-01

    Despite company attempts to reduce employee turnover by offering attractive salaries and benefits, Kushell notes that attrition continues at an alarming rate. He states that more than one of every three employees will change jobs over the next five years, a transition that will take its toll on company morale and productivity. The underlying factor, according to the author, is the quality of the working environment. A 1969 University of Michigan survey of 1,533 workers, at every occupation level, reported that all respondents ranked interesting work and authority to get the job done far ahead of good pay and job security. Sources of employee frustration include a stifling bureaucracy, excessive job expectations, and unsuitable jobs. The author suggests that top managers ask themselves whether they are missing out on or losing talented employees. If this is the case, there are several guidelines management should follow: improve communication between employees and top management; define expectations of the employee; and promote candor in the job interview. Kushell concludes that top executives can have an impact on turnover by paying attention to what employees really want rather than what management thinks they want.

  2. The Natural Resource Management Implications of Rural Property Turnover

    Directory of Open Access Journals (Sweden)

    Emily Mendham

    2012-12-01

    Full Text Available One aspect of recent rural change is in-migration, which is challenging the traditional dominance of production values in some areas. We explored the natural resource management implications of property turnover in two Australian regions. Our mixed-methods approach combined analysis of property sales records and spatially referenced landholder survey data with data from key informant interviews. Close to 50% of rural properties are expected to change hands between 2006 and 2016, double the change in the previous decade. This change is linked to the transformation of these rural areas, including the influx of non-farming rural landholders seeking amenity values. Our research suggests that property turnover of this scale has important implications for natural resource management. Newer and longer term owners were very different in terms of their values, attitudes, knowledge, land use, and management practices. A substantial proportion of these new property owners are absentees, which further complicates natural resource management, and our view is that a "business as usual" approach to the engagement of the new cohort of rural land managers is unlikely to be effective.

  3. Nurse Knowledge, Work Environment, and Turnover in Highly Specialized Pediatric End-of-Life Care.

    Science.gov (United States)

    Lindley, Lisa C; Cozad, Melanie J

    2017-07-01

    To examine the relationship between nurse knowledge, work environment, and registered nurse (RN) turnover in perinatal hospice and palliative care organizations. Using nurse intellectual capital theory, a multivariate analysis was conducted with 2007 National Home and Hospice Care Survey data. Perinatal hospice and palliative care organizations experienced a 5% turnover rate. The professional experience of advanced practice nurses (APNs) was significantly related to turnover among RNs (β = -.032, P < .05). Compared to organizations with no APNs professional experience, clinical nurse specialists and nurse practitioners significantly reduced RN turnover by 3 percentage points. No other nurse knowledge or work environment variables were associated with RN turnover. Several of the control variables were also associated with RN turnover in the study; Organizations serving micropolitan (β = -.041, P < .05) and rural areas (β = -.037, P < .05) had lower RN turnover compared to urban areas. Organizations with a technology climate where nurses used electronic medical records had a higher turnover rate than those without (β = .036, P < .05). The findings revealed that advanced professional experience in the form of APNs was associated with reductions in RN turnover. This suggests that having a clinical nurse specialist or nurse practitioner on staff may provide knowledge and experience to other RNs, creating stability within the organization.

  4. HUMAN RESOURCE PRACTICES AS DETERMINANTS OF EMPLOYEE TURNOVER: AN EMPIRICAL INVESTIGATION

    Directory of Open Access Journals (Sweden)

    Muhammad Aminu Bawa

    2005-01-01

    Full Text Available The volume of literature on the causes of employee turnover continues to grow. In spite of this, attempts to distinguish between the causes of voluntary and involuntary turnover in organizations, though recognized for quite some time, receive little attention from researchers. The two phenomena seem to be influenced by a different set of factors. There are clear-cut theoretical and empirical reasons for this assertion. The objective of this paper is to investigate the relationship between human resource (HR practices and employee turnover in Malaysia where companies are generally experiencing labour shortage and labour turnover. Using data collected from a census of managers, the study utilized Analysis of Variance (ANOVA and simple regression and tested hypotheses developed to investigate the relationship between HR practices and employee voluntary and involuntary turnover. The results show that (1 staffing process and employee monitoring were effective in reducing involuntary turnover, and (2 none of the HR practices were effective in reducing voluntary turnover. In other words, workers continue to leave or quit irrespective of the type of HR practices implemented. The paper concludes that economic factors such as availability of alternative jobs are most likely relevant in explaining the turnover process. Based on these findings, various strategies were suggested which have wider managerial and policy implications for the management of turnover in similar settings.

  5. Measuring worker turnover in long-term care: lessons from the better jobs better care demonstration.

    Science.gov (United States)

    Barry, Theresa Teta; Kemper, Peter; Brannon, S Diane

    2008-06-01

    Turnover among direct-care workers (DCWs) continues to be a challenge in long-term care. Both policy makers and provider organizations recognize this issue as a major concern and are designing efforts to reduce turnover among these workers. However, there is currently no standardized method of measuring turnover to define the scope of the problem or to assess the effectiveness of interventions. This article draws on our experience of the Better Jobs Better Care Demonstration (BJBC) to explicate some important issues in measuring and interpreting turnover related to interventions designed to improve DCW jobs. We used turnover data from a selected group of BJBC providers (N = 9) to demonstrate some of the measurement issues we uncovered in developing a turnover tracking system for BJBC. We also illustrate how the data elements collected in the tracking system make it possible to construct measures that are useful at both policy and practice levels. Differences in definitions of turnover and the data elements used to construct the measure can have large effects on turn over rates, how they are used, and what they mean. Policy makers, researchers, and managers who need comparative turnover information to address the impending demand for DCWs should be aware that turnover measures differ, and they should take steps to ensure that measures they use have common definitions and data elements.

  6. On-call work and physicians' turnover intention: the moderating effect of job strain.

    Science.gov (United States)

    Heponiemi, Tarja; Presseau, Justin; Elovainio, Marko

    2016-01-01

    Physician shortage and turnover are major problems worldwide. On-call duties may be among the risk factors of high turnover rates among physicians. We investigated whether having on-call duties is associated with physicians' turnover intention and whether job strain variables moderate this association. The present study was a cross-sectional questionnaire study among 3324 (61.6% women) Finnish physicians. The analyses were conducted using analyses of covariance adjusted for age, gender, response format, specialization status and employment sector. The results showed that job strain moderated the association between being on-call and turnover intention. The highest levels of turnover intention were among those who had on-call duties and high level of job strain characterized by high demands and low control opportunities. The lowest levels of turnover intention were among those who were not on-call and who had low strain involving low demands and high control. Also, job demands moderated the association between being on-call and turnover intention; turnover intention levels were higher among those with on-call duties and high demands than those being on-call and low demands. To conclude, working on-call was related to physicians' turnover intention particularly in those with high job strain. Health care organizations should focus more attention on working arrangements and scheduling of on-call work, provide a suitable working pace and implement means to increase physicians' participation and control over their job.

  7. Workplace Bullying and Turnover Intention: Exploring Work Engagement as a Potential Mediator.

    Science.gov (United States)

    Coetzee, Melinde; van Dyk, Jeannette

    2017-01-01

    Employees' turnover intentions may entail expensive consequences for companies. The study examined the mediating effect of work engagement in the relationship between workplace bullying and turnover intention. Using a cross-sectional sample of 373 employees, structural equation modeling and mediation analysis showed that perceptions of work- and person-related bullying were linked to low levels of vigor and dedication which in turn were associated with high turnover intention. Work engagement partially mediated the effect of high workplace bullying on high turnover intention. The results were interpreted from a social cognitive perspective and recommendations for practice were made.

  8. Birds on the move in the face of climate change: High species turnover in northern Europe.

    Science.gov (United States)

    Virkkala, Raimo; Lehikoinen, Aleksi

    2017-10-01

    Species richness is predicted to increase in the northern latitudes in the warming climate due to ranges of many southern species expanding northwards. We studied changes in the composition of the whole avifauna and in bird species richness in a period of already warming climate in Finland (in northern Europe) covering 1,100 km in south-north gradient across the boreal zone (over 300,000 km(2)). We compared bird species richness and species-specific changes (for all 235 bird species that occur in Finland) in range size (number of squares occupied) and range shifts (measured as median of area of occupancy) based on bird atlas studies between 1974-1989 and 2006-2010. In addition, we tested how the habitat preference and migration strategy of species explain species-specific variation in the change of the range size. The study was carried out in 10 km squares with similar research intensity in both time periods. The species richness did not change significantly between the two time periods. The composition of the bird fauna, however, changed considerably with 37.0% of species showing an increase and 34.9% a decrease in the numbers of occupied squares, that is, about equal number of species gained and lost their range. Altogether 95.7% of all species (225/235) showed changes either in the numbers of occupied squares or they experienced a range shift (or both). The range size of archipelago birds increased and long-distance migrants declined significantly. Range loss observed in long-distance migrants is in line with the observed population declines of long-distance migrants in the whole Europe. The results show that there is an ongoing considerable species turnover due to climate change and due to land use and other direct human influence. High bird species turnover observed in northern Europe may also affect the functional diversity of species communities.

  9. Social identity and the prison health worker: Implications for practitioner satisfaction and turnover intentions.

    Science.gov (United States)

    Stephenson, Amber L; Bell, Nicolette

    2017-08-23

    Delivering health care within the prison walls poses distinct and arduous challenges to the practitioner. Correctional health workers regularly face issues of overcrowding, increased prevalence of infectious disease, advancing age, deteriorating conditions, and patients with an inclination for violence. Still, regardless of the sizeable workforce, costs, and impact on community well-being, correctional health is often overlooked in health services delivery research. The aim of this study was to better understand the unique nature of delivering services in the prison context through the lens of social identity theory and further explore practitioner satisfaction and retention. A survey design was used in this study, sampling clinicians in a state department of corrections in the United States. Using the data from 317 respondents, the study explored the relationship between professional identification and perceived organizational support as they impact job satisfaction and turnover intention and while controlling for burnout. Using nested ordinary least squares regression and nested logistic regression, the results showed that professional identification and perceived organizational support were positively associated with job satisfaction. Perceived organizational support was negatively and significantly related to turnover intentions. This article adds originality and value to the literature by using social identity theory to address the occupational perceptions of a large, yet often underrepresented and underexplored, subsector of the health workforce. The results highlight several areas where health care managers, whether from correctional or noncorrectional environments, could implement policy and procedure changes to further engage and retain the clinical workforce. To engage and retain the health worker population, managers must consider identification-reinforcing interventions that align with the self-concept and visibly display gestures of organizational

  10. The Effect of Business Ethical Values on Turnover Intention: Mediating Role of Person-organization Fit Dimensions. The Case of Iranian Teachers in Public School

    Directory of Open Access Journals (Sweden)

    Mehdi Abzari

    2015-03-01

    Full Text Available Business ethical values are considered as one of the important and comprehensive issues in the world nowadays. Disputing about these values and ignoring ethical principles in workplaces influence employee’s job attitude and provide backgrounds of turnover for employees, and because of this, many costs are put on organizations. Therefore, this study seeks to examine types and levels of business ethical values effects on turnover intention and also concentrates on mediating the role of person-organization fit dimensions. The statistical population of this study includes active teachers of public schools in Isfahan and Yazd. In order to select sample members, classification sampling method has been used. Then, the questionnaire is used to gathering the data. The results of this study indicated that business ethical values influence employee’s turnover intention directly and indirectly, and level of these indirect effects was stronger than direct ones. Also, the results indicate that different dimensions of person-organization fit have low correlation with each one of other variables, and these dimensions are mediators in the relationship between business ethical values and turnover intention.

  11. Rapid Detection of Pathogens

    Energy Technology Data Exchange (ETDEWEB)

    David Perlin

    2005-08-14

    Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents. Many select agents are highly transmissible in the early stages of disease, and it is critical to identify infected patients and limit the risk to the remainder of the population and to stem potential panic in the general population. Nucleic acid-based molecular approaches for identification overcome many of the deficiencies associated with conventional culture methods by exploiting both large- and small-scale genomic differences between organisms. PCR-based amplification of highly conserved ribosomal RNA (rRNA) genes, intergenic sequences, and specific toxin genes is currently the most reliable approach for bacterial, fungal and many viral pathogenic agents. When combined with fluorescence-based oligonucleotide detection systems, this approach provides real-time, quantitative, high fidelity analysis capable of single nucleotide allelic discrimination (4). These probe systems offer rapid turn around time (<2 h) and are suitable for high throughput, automated multiplex operations that are critical for clinical diagnostic laboratories. In this pilot program, we have used molecular beacon technology invented at the Public health Research Institute to develop a new generation of molecular probes to rapidly detect important agents of infectious diseases. We have also developed protocols to rapidly extract nucleic acids from a variety of clinical specimen including and blood and tissue to for detection in the molecular assays. This work represented a cooperative research development program between the Kramer-Tyagi/Perlin labs on probe development

  12. Impact of peat mining, and restoration on methane turnover potentials and methane-cycling microorganisms in a northern bog.

    Science.gov (United States)

    Reumer, Max; Harnisz, Monika; Lee, Hyo Jung; Reim, Andreas; Grunert, Oliver; Putkinen, Anuliina; Fritze, Hannu; Bodelier, Paul L E; Ho, Adrian

    2017-11-27

    Ombrotrophic peatlands are a recognized global carbon reservoir. Without restoration and peat regrowth, harvested peatlands are dramatically altered, impairing its carbon sink function, with consequences for methane turnover. Previous studies determined the impact of commercial mining on the peat physico-chemical properties, and the effects on methane turnover. However, the response of the underlying microbial communities catalyzing methane production and oxidation have so far received little attention. We hypothesize that with the return of Sphagnum post-harvest, methane turnover potentials and the corresponding microbial communities will converge in a natural and restored peatland. To address our hypothesis, we determined the potential methane production and oxidation rates in a natural (as a reference), actively mined, abandoned, and restored peatland over two consecutive years. In all sites, the methanogenic and methanotrophic population size were enumerated using qPCR assays targeting the mcrA and pmoA genes, respectively. Shifts in the community composition was determined using Illumina MiSeq sequencing of the mcrA gene, and a pmoA-based t-RFLP analysis, complemented by cloning and sequence analysis of the mmoX gene. Peat mining adversely affected methane turnover potentials, but rates recovered in the restored site. The recovery in potential activity was reflected in the methanogenic and methanotrophic abundances. However, the microbial community composition was altered, more pronounced for the methanotrophs. Overall, we observed a lag between the recovery of the methanogenic/methanotrophic activity and the return of the corresponding microbial communities, suggesting a longer duration (>15 years) is needed to reverse mining-induced effects on the methane-cycling microbial communities.ImportanceOmbrotrophic peatlands are a crucial carbon sink, but this environment is also a source of methane, an important greenhouse gas. Methane emission in peatlands is

  13. Sales Force Turnover: An Exploratory Study of the Indian Insurance Sector = Prihodek od prodaje: raziskovalna študija o indijskem zavarovalniškem sektorju

    Directory of Open Access Journals (Sweden)

    Suman Pathak

    2010-03-01

    Full Text Available The insurance sector in India is rising rapidly to bring in growthand employment opportunities. Insurance companies are basicallyhuman intensive, and human resources act as an undoubteddifferentiator. Quality manpower and its retention would act as alitmus test. Turnover of sales force has been high because of lowentry and exit barriers. The paper addresses issues of recruitment,retention and turnover of sales force in insurance companies.An attempt is made to integrate them to Maslow’s NeedHierarchy. A survey was conducted among 350 employees whoworked in or had left insurance companies to analyze factors thatinfluenced their decisions and job satisfaction. The data were treatedwith factor analysis. Factors such as Safety & Security, Social &Esteem and Personal Work Style emerged as the influencers tojoin insurance companies. Primary Needs and Social & Self EsteemNeeds were the factors associated with job satisfaction; Stress,Career Advancement and Work Environment emerged as factorsfor leaving the companies.

  14. Carbon turnover and sequestration potential of fodder radish cover crop

    DEFF Research Database (Denmark)

    Mutegi, James; Petersen, Bjørn Molt; Munkholm, Lars Juhl

    2013-01-01

    We studied fodder radish carbon turnover as affected by soil tillage in Foulum, Denmark. Actively growing fodder radish monoliths from direct-drilled (DD) and conventionally tilled (CT) plots were extracted and labelled regularly with 14C isotope across their entire growth period. At the end...... of the fodder radish growth cycle, labelled biomass was harvested and incorporated into the same monolith. These monoliths were destructively sampled at biomass incorporation, 4, 8 and 18 months after incorporation. For each sampling period, soil and root samples were taken at 0- to 10-, 10- to 25-, and 25......-SIM model forecast, we estimated that over a 30-yr period of continuous autumn fodder radish establishment, at least 4.9 t C/ha fodder radish C with a residence time of more than 20 yr could be stored in the soil....

  15. System wide cofactor turnovers can propagate metabolic stability between pathways

    DEFF Research Database (Denmark)

    Yang, Y.; Guan, Y.H.; Villadsen, John

    2016-01-01

    the metabolic networks studied were invariably associated with living cells. Nowadays, there are needs to reconstruct metabolic networks, and so metabolic homeostasis cannot be taken for granted. For metabolic steady state, enzyme feedback control has been known to explain why metabolites in metabolic pathways......Metabolic homeostasis, or low-level metabolic steady state, has long been taken for granted in metabolic engineering, and research priority has always been given to understand metabolic flux control and regulation of the reaction network. In the past, this has not caused concerns because....... Furthermore, we elaborated the criteria to tell if a multi-enzyme over-all reaction path is of in vivo nature or not at the metabolic level. As new findings, we discovered that there are interactions between the enzyme feedback inhibition and the CI turnover, and such interactions may well lead to metabolic...

  16. Evaluating nurse turnover: comparing attitude surveys and exit interviews.

    Science.gov (United States)

    Fottler, M D; Crawford, M A; Quintana, J B; White, J B

    1995-01-01

    High turnover rates among hospital nurses demand rigorous and valid processes of research to determine the reasons motivating such attrition. In most hospitals, the exit interview often provides the only relevant data. The case study reported here examines the relative effectiveness of exit interviews and an employee attitude survey in generating data that are useful in managing nurse retention. The conclusion reached is that the attitude survey generates more data and higher-quality data. Further, the study shows that the use of open-ended questions can provide useful information and probably should be the starting point in developing or supplementing an attitude survey for nurses. Recommendations for improving the usefulness and validity of nurse attitude surveys and exit interviews in managing nurse retention are provided.

  17. Serum leptin is correlated to high turnover in osteoporosis.

    Science.gov (United States)

    Hipmair, Gunter; Böhler, Nikolaus; Maschek, Wilma; Soriguer, Federico; Rojo-Martínez, Gemma; Schimetta, Wolfgang; Pichler, Robert

    2010-01-01

    Clinical data have suggested that obesity protects against osteoporosis. Leptin, mainly secreted by white adipose tissue, might be involved by mediating an effect on bone metabolism. This study was conducted to investigate a possible relationship of leptin and bone turn-over in postmenopausal women with osteoporosis. We measured bone mineral density (BMD), serum leptin levels and markers of bone metabolism, including osteocalcin and cross-laps in 44 patients with osteoporosis. The main group consisted of 32 postmenopausal women. Mean serum leptin was 13.1 microg/L and showed no statistically significant difference to the levels measured in a collective of normal persons adjusted for age and BMI. When related to serum cross-laps as markers of bone resorption, a positive correlation (posteoporosis.

  18. Protein turnover during in vitro tissue engineering.

    Science.gov (United States)

    Li, Qiyao; Chang, Zhen; Oliveira, Gisele; Xiong, Maiyer; Smith, Lloyd M; Frey, Brian L; Welham, Nathan V

    2016-03-01

    Repopulating acellular biological scaffolds with phenotypically appropriate cells is a promising approach for regenerating functional tissues and organs. Under this tissue engineering paradigm, reseeded cells are expected to remodel the scaffold by active protein synthesis and degradation; however, the rate and extent of this remodeling remain largely unknown. Here, we present a technique to measure dynamic proteome changes during in vitro remodeling of decellularized tissue by reseeded cells, using vocal fold mucosa as the model system. Decellularization and recellularization were optimized, and a stable isotope labeling strategy was developed to differentiate remnant proteins constituting the original scaffold from proteins newly synthesized by reseeded cells. Turnover of matrix and cellular proteins and the effects of cell-scaffold interaction were elucidated. This technique sheds new light on in vitro tissue remodeling and the process of tissue regeneration, and is readily applicable to other tissue and organ systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Turnover of carbon in the {sup 13}C-urea breath test for the detection of Helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Vladimir E.; Andreazzi, Mariana; Cury, Caio S.; Bassetto Junior, Carlos A.Z.; Rodrigues, Maria A.M.; Ducatti, Carlos, E-mail: vladimir@ibb.unesp.br, E-mail: ducatti@ibb.unesp.br, E-mail: mariana.andreazazi@gmail.com, E-mail: caiocury@hotmail.com, E-mail: juniorbassett@hotmail.com, E-mail: mariar@fmb.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Botucatu, SP (Brazil)

    2013-07-01

    To obtain a standard protocol for the application of {sup 13}C-urea breath test ({sup 13}C-UBT) analyzed by Isotope Ratio Mass Spectrometer (IRMS) to detect helicobacter pylori infection in the population is necessary to know the behavior of the turnover of {sup 13}C during the test in different individuals. The aims of this study was to find out a pattern for the turnover of the {sup 13}C in the {sup 13}C-UBT, analyzed by IRMS, in patients infected with H. pylori, in a Brazilian population, to define a protocol test application. We found that the isotopic ratio {sup 13}C/{sup 12}C in expired CO{sub 2} from patients infected with H. pylori and subjected to {sup 13}C-UBT does not follow a single pattern of behavior. However this behavior can be similar in subjects having the same maximum values following an inverse proportional relationship between the maximum value and the time of appearance in the curve. (author)

  20. Feasibility of protein turnover studies in prototroph Saccharomyces cerevisiae strains.

    Science.gov (United States)

    Martin-Perez, Miguel; Villén, Judit

    2015-04-07

    Quantitative proteomics studies of yeast that use metabolic labeling with amino acids rely on auxotrophic mutations of one or more genes on the amino acid biosynthesis pathways. These mutations affect yeast metabolism and preclude the study of some biological processes. Overcoming this limitation, it has recently been described that proteins in a yeast prototrophic strain can also be metabolically labeled with heavy amino acids. However, the temporal profiles of label incorporation under the different phases of the prototroph's growth have not been examined. Labeling trajectories are important in the study of protein turnover and dynamics, in which label incorporation into proteins is monitored across many time points. Here we monitored protein labeling trajectories for 48 h after a pulse with heavy lysine in a yeast prototrophic strain and compared them with those of a lysine auxotrophic yeast. Labeling was successful in prototroph yeast during exponential growth phase but not in stationary phase. Furthermore, we were able to determine the half-lives of more than 1700 proteins during exponential phase of growth with high accuracy and reproducibility. We found a median half-life of 2 h in both strains, which corresponds with the cellular doubling time. Nucleolar and ribosomal proteins showed short half-lives, whereas mitochondrial proteins and other energy production enzymes presented longer half-lives. Except for some proteins involved in lysine biosynthesis, we observed a high correlation in protein half-lives between prototroph and auxotroph strains. Overall, our results demonstrate the feasibility of using prototrophs for proteomic turnover studies and provide a reliable data set of protein half-lives in exponentially growing yeast.

  1. Sclerostin as a novel marker of bone turnover in athletes

    Directory of Open Access Journals (Sweden)

    A Zagrodna

    2016-02-01

    Full Text Available Sclerostin is a protein secreted by osteocytes that acts as an inhibitor of bone formation. It has been shown that physical activity affects sclerostin concentration and thus bone remodelling. The aim of the study was to evaluate serum concentrations of sclerostin, selected bone turnover markers (PTH, P1NP, 25(OH D3 and the intake of calcium and vitamin D in physically active versus sedentary men. A total of 59 healthy men aged 17-37 were enrolled in the study (43 athletes and 16 non-athletes. The mean sclerostin concentration in the group of athletes (A was significantly higher than in non-athletes (NA (35.3±8.9 vs 28.0±5.6 pmol• l-1, p= 0.004. A compared with NA had higher concentrations of P1NP (145.6±77.5 vs 61.2±22.3 ng• ml-1, p= <0.0001 and 25(OHD3 (16.9±8.4 vs 10.3±4.3 ng • ml-1, p= 0.004 and lower concentrations of PTH (25.8±8.3 vs 38.2±11.5 pg• ml-1, p= <0.0001. Vitamin D deficiency was found in 77% of A and 100% of NA. A and NA had similar daily energy intake. They did not differ as to the intake of calcium and vitamin D. We observed a negative correlation between the serum concentrations of sclerostin and calcium in the studied subjects. Our results suggest that regular, long-lasting physical training may be associated with higher concentration of sclerostin. It seems that increased sclerostin is not related to other bone turnover markers (PTH, P1NP.

  2. The need for power, brain norepinephrine turnover and learning.

    Science.gov (United States)

    McClelland, D C; Davidson, R; Saron, C; Floor, E

    1980-03-01

    This experiment was designed to explore whether brain norepinephrine (NE) serves as a specific reward system for the power drive. Previous research has indicated that 3-methoxy-4-hydroxyphenyl glycol (MHPG), a urinary metabolite reflecting central NE turnover, is positively correlated with features of assertiveness which one might expect of a person high in the need for power (n power) or in a state of aroused power motivation. Twenty-seven male undergraduates, 13 of whom were high and 14 of whom were low in n power as assessed by a TAT measure, were recruited as subjects. Before and after the laboratory session, subjects voided all urine and concentrations of epinephrine, norepinephrine and MHPG were obtained from samples. The laboratory task consisted of 20 picture-word pairs in which the subject had to learn to anticipate the word associated with each picture before the word was presented. Five pairs of stimuli in each of the following picture-word combinations were presented 12 times: neutral-neutral, neutral-power, power-neutral and power-power. The results revealed that, as predicted, subjects high in n power learn most power-related material faster than subjects low in n power. The need for achievement is unrelated to the learning of any picture-word pairs. The neurochemical data indicated that subjects maintaining a relatively high MHPG excretion rate during the experiment who were also high in n power showed the greatest mastery of power related compared with neutral picture-word pairs. These findings are consistent with the hypothesis that brain NE turnover is specifically related to the learning of power-related responses in subjects high in n power.

  3. Modelling nitrate transport and turnover in a lowland catchment system

    Science.gov (United States)

    Wriedt, Gunter; Rode, Michael

    2006-08-01

    SummaryNitrate transport in groundwater dominated lowland catchment systems is influenced by complex and spatially distributed physical and chemical interactions. A modelling approach was developed combining a distributed soil nitrogen model with a three-dimensional groundwater model and a reactive transport model linking nitrate turnover and availability of reaction partners such as pyrite and organic matter. The modelling approach was applied to a hypothetical case study based on data from the pleistocene lowland catchment "Schaugraben" (20 km 2) in the North of Saxony-Anhalt, with focus on the investigation of interactions of spatially distributed transport and chemical processes. The modelling approach could successfully simulate transport and turnover of nitrate in a groundwater dominated catchment. The advancement of the nitrate front and the corresponding depletion of pyrite as well as the distribution of seepage fluxes and nitrate concentrations in seepage water in the channel system showed distinct spatial variation. Surface water nitrate concentrations corresponding to the average soil leachate concentrations were not completely reached after a simulation period of 200 years for a conservative transport simulation. Under reactive conditions, about 80% of the nitrate was lost due to denitrification. Given a uniformly distributed input of nitrate, drain loads developed in a sigmoidal curve defined only by travel time distribution. The average travel time was 93 years. A distributed input of nitrate resulted in reduction of travel time to 80 years due to the different arrangement of source areas and flow. The modelling approach is a step towards bridging the gap between simple large scale models and detailed small scale studies, maintaining process orientation while allowing to consider landscape heterogeneity.

  4. Functional divergence and evolutionary turnover in mammalian phosphoproteomes.

    Directory of Open Access Journals (Sweden)

    Luca Freschi

    2014-01-01

    Full Text Available Protein phosphorylation is a key mechanism to regulate protein functions. However, the contribution of this protein modification to species divergence is still largely unknown. Here, we studied the evolution of mammalian phosphoregulation by comparing the human and mouse phosphoproteomes. We found that 84% of the positions that are phosphorylated in one species or the other are conserved at the residue level. Twenty percent of these conserved sites are phosphorylated in both species. This proportion is 2.5 times more than expected by chance alone, suggesting that purifying selection is preserving phosphoregulation. However, we show that the majority of the sites that are conserved at the residue level are differentially phosphorylated between species. These sites likely result from false-negative identifications due to incomplete experimental coverage, false-positive identifications and non-functional sites. In addition, our results suggest that at least 5% of them are likely to be true differentially phosphorylated sites and may thus contribute to the divergence in phosphorylation networks between mouse and humans and this, despite residue conservation between orthologous proteins. We also showed that evolutionary turnover of phosphosites at adjacent positions (in a distance range of up to 40 amino acids in human or mouse leads to an over estimation of the divergence in phosphoregulation between these two species. These sites tend to be phosphorylated by the same kinases, supporting the hypothesis that they are functionally redundant. Our results support the hypothesis that the evolutionary turnover of phosphorylation sites contributes to the divergence in phosphorylation profiles while preserving phosphoregulation. Overall, our study provides advanced analyses of mammalian phosphoproteomes and a framework for the study of their contribution to phenotypic evolution.

  5. Single Turnover Autophosphorylation Cycle of the PKA RIIβ Holoenzyme.

    Science.gov (United States)

    Zhang, Ping; Knape, Matthias J; Ahuja, Lalima G; Keshwani, Malik M; King, Charles C; Sastri, Mira; Herberg, Friedrich W; Taylor, Susan S

    2015-07-01

    To provide tight spatiotemporal signaling control, the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) holoenzyme typically nucleates a macromolecular complex or a "PKA signalosome." Using the RIIβ holoenzyme as a prototype, we show how autophosphorylation/dephosphorylation of the RIIβ subunit, as well as cAMP and metal ions, contribute to the dynamics of PKA signaling. While we showed previously that the RIIβ holoenzyme could undergo a single turnover autophosphorylation with adenosine triphosphate and magnesium (MgATP) and trap both products in the crystal lattice, we asked here whether calcium could trap an ATP:RIIβ holoenzyme since the RIIβ holoenzyme is located close to ion channels. The 2.8Å structure of an RIIβp2:C2:(Ca2ADP)2 holoenzyme, supported by biochemical and biophysical data, reveals a trapped single phosphorylation event similar to MgATP. Thus, calcium can mediate a single turnover event with either ATP or adenosine-5'-(β,γ-imido)triphosphate (AMP-PNP), even though it cannot support steady-state catalysis efficiently. The holoenzyme serves as a "product trap" because of the slow off-rate of the pRIIβ subunit, which is controlled by cAMP, not by phosphorylation of the inhibitor site. By quantitatively defining the RIIβ signaling cycle, we show that release of pRIIβ in the presence of cAMP is reduced by calcium, whereas autophosphorylation at the phosphorylation site (P-site) inhibits holoenzyme reassociation with the catalytic subunit. Adding a single phosphoryl group to the preformed RIIβ holoenzyme thus creates a signaling cycle in which phosphatases become an essential partner. This previously unappreciated molecular mechanism is an integral part of PKA signaling for type II holoenzymes.

  6. Fossils and a large molecular phylogeny show that the evolution of species richness, generic diversity, and turnover rates are disconnected.

    Science.gov (United States)

    Xing, Yaowu; Onstein, Renske E; Carter, Richard J; Stadler, Tanja; Peter Linder, H

    2014-10-01

    The magnitude and extent of global change during the Cenozoic is remarkable, yet the impacts of these global changes on the biodiversity and evolutionary dynamics of species diversification remain poorly understood. To investigate this question, we combine paleontological and neontological data for the angiosperm order Fagales, an ecologically important clade of about 1370 species of trees with an exceptional fossil record. We show differences in patterns of accumulation of generic diversity, species richness, and turnover rates for Fagales. Generic diversity evolved rapidly since the Late Cretaceous and peaked during the Eocene or Oligocene. Turnover rates were high during periods of extreme global climate change, but relatively low when the climate remained stable. Species richness accumulated gradually throughout the Cenozoic, possibly at an accelerated pace after the Middle Miocene. Species diversification occurred in new environments: Quercoids radiating in Oligocene subtropical seasonally arid habitats, Casuarinaceae in Australian pyrophytic biomes, and Betula in Late Neogene holarctic habitats. These radiations were counterbalanced by regional extinctions in Late Neogene mesic warm-temperate forests. Thus, the overall diversification at species level is linked to regional radiations of clades with appropriate ecologies exploiting newly available habitats. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  7. An Exploratory Study of the Role of Human Resource Management in Models of Employee Turnover

    Science.gov (United States)

    Ozolina-Ozola, Iveta

    2016-01-01

    The purpose of this paper is to present the study results of the human resource management role in the voluntary employee turnover models. The mixed methods design was applied. On the basis of the results of the search and evaluation of publications, the 16 models of employee turnover were selected. Applying the method of content analysis, the…

  8. Team turnover and task conflict: A longitudinal study on the moderating effects of collective experience

    NARCIS (Netherlands)

    Kuypers, A.P.A.; Günter, H.; van Emmerik, I.H.

    2015-01-01

    Team turnover can be harmful to a team in many ways. This study examined whether a team’s collective experience (team organizational tenure) attenuates the association between team turnover and task conflict changes. Differing from prior research, our study used a longitudinal design to assess the

  9. Labour turnover and its effects on performance : an empirical test using firm data

    NARCIS (Netherlands)

    Glebbeek, A.C.; Bax, E.H.

    2002-01-01

    In this article we test the hypothesis that the relationship between labour turnover and the economic performance of the firm is bell-shaped: a turnover level too low has a negative effect and likewise does a level too high. Our analysis is based on economic performance data of 110 offices of a temp

  10. Academic Staff Turnover Intention in Madda Walabu University, Bale Zone, South-East Ethiopia

    Science.gov (United States)

    Yimer, Ibrahim; Nega, Rahel; Ganfure, Gemechu

    2017-01-01

    Turnover is a voluntary cessation of membership of an organization by an employee. Employee retention is one of the challenges facing several organizations in both the developed and developing countries of the world. It is profitable to proactively react for possible staff turnover intentions. This research was carried out to determine the…

  11. Why turnover matters in self-managing work teams : Learning, social integration, and task flexibility

    NARCIS (Netherlands)

    van der Vegt, G.S.; Bunderson, S.; Kuipers, B.

    This study considers how turnover in self-managing work teams influences the team interaction processes that promote effective task accomplishment. Drawing from research on self-managing work teams and group process, the authors propose that team turnover affects performance in self-managing teams

  12. Nursing Home Staff Turnover: Impact on Nursing Home Compare Quality Measures

    Science.gov (United States)

    Castle, Nicholas G.; Engberg, John; Men, Aiju

    2007-01-01

    Purpose: We used data from a large sample of nursing homes to examine the association between staff turnover and quality. Design and Methods: The staff turnover measures came from primary data collected from 2,840 nursing homes in 2004 (representing a 71% response rate). Data collection included measures for nurse aides, licensed practical nurses,…

  13. Impact of transamination reactions and protein turnover on labeling dynamics in C-13-labeling experiments

    DEFF Research Database (Denmark)

    Grotkjær, Thomas; Åkesson, M.; Christensen, Bjarke

    2004-01-01

    that carbon exchange due to transamination and protein turnover can significantly increase the required time needed for metabolites in the TCA cycle to reach isotopic steady state, which is in agreement with published experimental observations. On the other hand, transamination and protein turnover will speed...

  14. An Unfolding Model of Voluntary Turnover of Air Force Reservists and Air National Guard Members

    Science.gov (United States)

    2004-03-01

    variables and turnover intentions. Journal of Managerial Issues , 15, 175-190. Cohen, A. (1995). An examination of the relationship between work...organizational commitment, intention to leave and voluntary turnover. Journal of Managerial Issues , 11, 493-513. Lee, T. W., & Mitchell, T. R. (1994

  15. An Analysis of Turnover Intentions: A Reexamination of Air Force Civil Engineering Company Grade Officers

    Science.gov (United States)

    2012-03-01

    Approved: ________//SIGNED//_________________ _2-Mar-2012_ Alfred E. Thal, Jr., PhD (Chairman) Date ________//SIGNED...OPTEMPO) and turnover intentions might have a curvilinear relationship (Castro & Adler , 1999). This curvilinear relationship could change the...home deployment cycle. Additionally, OPTEMPO and turnover intentions might have a curvilinear relationship (Castro & Adler , 1999). The curvilinear

  16. Organizational turnover as endogenous precursor of industry dynamics and organizational dissolution

    NARCIS (Netherlands)

    Cattani, Gino; Pennings, Johannes M.; Wezel, Filippo Carlo

    2002-01-01

    This paper studies the effect of organizational turnover on firm survival within the Dutch accounting service industry during the period 1880-1986. We address three issues: (1) estimating the effect of organizational turnover on organizational dissolution; (2) showing the significance of propinquity

  17. Dynamic Effects of Teacher Turnover on the Quality of Instruction. Working Paper 170

    Science.gov (United States)

    Hanushek, Eric A.; Rivkin, Steven G.; Schiman, Jeffrey C.

    2016-01-01

    It is widely believed that teacher turnover adversely affects the quality of instruction in urban schools serving predominantly disadvantaged children, and a growing body of research investigates various components of turnover effects. The evidence at first seems contradictory, as the quality of instruction appears to decline following turnover…

  18. The Teacher Labour Market, Teacher Turnover and Disadvantaged Schools: New Evidence for England

    Science.gov (United States)

    Allen, Rebecca; Burgess, Simon; Mayo, Jennifer

    2018-01-01

    We study the market for teachers in England, in particular teacher turnover. We show that there is a positive raw association between the level of school disadvantage and the turnover rate of its teachers. This association diminishes as we control for school, pupil and local teacher labour market characteristics, but is not eliminated. The…

  19. Toward a Theoretical Model of Employee Turnover: A Human Resource Development Perspective

    Science.gov (United States)

    Peterson, Shari L.

    2004-01-01

    This article sets forth the Organizational Model of Employee Persistence, influenced by traditional turnover models and a student attrition model. The model was developed to clarify the impact of organizational practices on employee turnover from a human resource development (HRD) perspective and provide a theoretical foundation for research on…

  20. A Study on the Employee Turnover Antecedents in ITES/BPO Sector

    Science.gov (United States)

    Sree Rekha, K. R.; Kamalanabhan, T. J.

    2010-01-01

    This paper aims at testing a conceptual model connecting variables of the internal and external work environment to ITES/BPO employee turnover. Based on the gaps identified from the literature that no single model explains in a comprehensive way as to why, people choose to leave and the lack of turnover studies on call centers located in India.…

  1. Short-Term Effects of Midseason Coach Turnover on Team Performance in Soccer

    Science.gov (United States)

    Balduck, Anne-Line; Buelens, Marc; Philippaerts, Renaat

    2010-01-01

    The present study addressed the issue of short-term performance effects of midseason coach turnover in soccer. The goal of this study was to examine this effect on subsequent short-term team performance. The purposes of this study were to (a) examine whether midseason coach turnover improved results in the short term, and (b) examine how team…

  2. Impact of euthanasia rates, euthanasia practices, and human resource practices on employee turnover in animal shelters.

    Science.gov (United States)

    Rogelberg, Steven G; Reeve, Charlie L; Spitzmüller, Christiane; DiGiacomo, Natalie; Clark, Olga L; Teeter, Lisa; Walker, Alan G; Starling, Paula G; Carter, Nathan T

    2007-03-01

    To examine the effects of euthanasia rates, euthanasia practices, and human resource practices on the turnover rate among employees with euthanasia responsibilities at animal shelters. Cross-sectional original study. 36 shelters across the United States that employed at least 5 full-time employees and performed euthanasia on site. By mail, 1 survey was sent to each shelter. Surveys were completed by a senior member of management and were returned by mail. Questions assessed characteristics (eg, euthanasia rates) and practices of the animal shelter, along with employee turnover rates. By use of correlation coefficients and stepwise regression analyses, key predictors of turnover rates among employees with euthanasia responsibilities were investigated. Employee turnover rates were positively related to euthanasia rate. Practices that were associated with decreased turnover rates included provision of a designated euthanasia room, exclusion of other live animals from vicinity during euthanasia, and removal of euthanized animals from a room prior to entry of another animal to be euthanized. Making decisions regarding euthanasia of animals on the basis of factors other than behavior and health reasons was related to increased personnel turnover. With regard to human resources practices, shelters that used a systematic personnel selection procedure (eg, standardized testing) had comparatively lower employee turnover. Data obtained may suggest several specific avenues that can be pursued to mitigate turnover among employees with euthanasia responsibilities at animal shelters and animal control or veterinary medical organizations.

  3. Why Agriculture Teachers Leave: A National Examination of Turnover Intentions and Work-Family Conflict

    Science.gov (United States)

    Sorensen, Tyson J.; McKim, Aaron J.; Velez, Jonathan J.

    2016-01-01

    Using data from a random sample of secondary school agriculture teachers in the United States, this study explored the work-family conflict and turnover intentions of agriculture teachers. Additionally, this study sought to determine the relationship between work-family conflict and turnover intentions among agriculture teachers. Work-family…

  4. High bone turnover is associated with low bone mass and spinal fracture in postmenopausal women

    DEFF Research Database (Denmark)

    Ravn, Pernille; Rix, M; Andreassen, H

    1997-01-01

    A group of 366 healthy, white postmenopausal women, aged 50-81 years, mean age 66 years, were selected from the screened population of Scandinavians who were part of a multicenter study of the efficacy of tiludronate, a new bisphosphonate, in established postmenopausal osteoporosis. Eighty-eight ......, and prevalence of spinal fracture, which supports the theory that high bone turnover is a risk factor for spinal fracture and osteoporosis.......A group of 366 healthy, white postmenopausal women, aged 50-81 years, mean age 66 years, were selected from the screened population of Scandinavians who were part of a multicenter study of the efficacy of tiludronate, a new bisphosphonate, in established postmenopausal osteoporosis. Eighty...... resorption was assessed by measurement of the urinary excretion of type I collagen degradation products by the CrossLaps enzyme-linked immunoassay (ELISA). Bone formation was assessed by ELISA measurement of the N-terminal-midfragment as well as the intact serum osteocalcin (OCN-MID), thus omitting...

  5. Controls on terrestrial carbon feedbacks by productivity versus turnover in the CMIP5 Earth System Models

    Science.gov (United States)

    Koven, C. D.; Chambers, J. Q.; Georgiou, K.; Knox, R.; Negron-Juarez, R.; Riley, W. J.; Arora, V. K.; Brovkin, V.; Friedlingstein, P.; Jones, C. D.

    2015-09-01

    To better understand sources of uncertainty in projections of terrestrial carbon cycle feedbacks, we present an approach to separate the controls on modeled carbon changes. We separate carbon changes into four categories using a linearized, equilibrium approach: those arising from changed inputs (productivity-driven changes), and outputs (turnover-driven changes), of both the live and dead carbon pools. Using Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations for five models, we find that changes to the live pools are primarily explained by productivity-driven changes, with only one model showing large compensating changes to live carbon turnover times. For dead carbon pools, the situation is more complex as all models predict a large reduction in turnover times in response to increases in productivity. This response arises from the common representation of a broad spectrum of decomposition turnover times via a multi-pool approach, in which flux-weighted turnover times are faster than mass-weighted turnover times. This leads to a shift in the distribution of carbon among dead pools in response to changes in inputs, and therefore a transient but long-lived reduction in turnover times. Since this behavior, a reduction in inferred turnover times resulting from an increase in inputs, is superficially similar to priming processes, but occurring without the mechanisms responsible for priming, we call the phenomenon "false priming", and show that it masks much of the intrinsic changes to dead carbon turnover times as a result of changing climate. These patterns hold across the fully coupled, biogeochemically coupled, and radiatively coupled 1 % yr-1 increasing CO2 experiments. We disaggregate inter-model uncertainty in the globally integrated equilibrium carbon responses to initial turnover times, initial productivity, fractional changes in turnover, and fractional changes in productivity. For both the live and dead carbon pools, inter-model spread in

  6. Numbers of simultaneous turnovers calculated from anesthesia or operating room information management system data.

    Science.gov (United States)

    Dexter, Franklin; Marcon, Eric; Aker, John; Epstein, Richard H

    2009-09-01

    More personnel are needed to turn over operating rooms (ORs) promptly when there are more simultaneous turnovers. Anesthesia and/or OR information management system data can be analyzed statistically to quantify simultaneous turnovers to evaluate whether to add an additional turnover team. Data collected for each case at a six OR facility were room, date of surgery, time of patient entry into the OR, and time of patient exit from the OR. The number of simultaneous turnovers was calculated for each 1 min of 122 4-wk periods. Our end point was the reduction in the daily minutes of simultaneous turnovers exceeding the number of teams caused by the addition of a team. Increasing from two turnover teams to three teams reduced the mean daily minutes of simultaneous turnovers exceeding the numbers of teams by 19 min. The ratio of 19 min to 8 h valued the time of extra personnel as 4.0% of the time of OR staff, surgeons, and anesthesia providers. Validity was suggested by other methods of analyses also suggesting staffing for three simultaneous turnovers. Discrete-event simulation showed that the reduction in daily minutes of turnover times from the addition of a team would likely match or exceed the reduction in the daily minutes of simultaneous turnovers exceeding the numbers of teams. Confidence intervals for daily minutes of turnover times achieved by increasing from two to three teams were calculated using successive 4-wk periods. The distribution was sufficiently close to normal that accurate confidence intervals could be calculated using Student's t distribution (Lilliefors' test P = 0.58). Analysis generally should use 13 4-wk periods as increasing the number of periods from 6 to 13 significantly reduced the coefficient of variation of the averages but not increasing the number of periods from 6 to 9 or from 9 to 13. The number of simultaneous turnovers can be calculated for each 1 min over 1 yr. The reduction in the daily minutes of simultaneous turnovers

  7. Turnover of branched actin filament networks by stochastic fragmentation with ADF/cofilin.

    Science.gov (United States)

    Reymann, Anne-Cécile; Suarez, Cristian; Guérin, Christophe; Martiel, Jean-Louis; Staiger, Christopher J; Blanchoin, Laurent; Boujemaa-Paterski, Rajaa

    2011-07-15

    Cell motility depends on the rapid assembly, aging, severing, and disassembly of actin filaments in spatially distinct zones. How a set of actin regulatory proteins that sustains actin-based force generation during motility work together in space and time remains poorly understood. We present our study of the distribution and dynamics of Arp2/3 complex, capping protein (CP), and actin-depolymerizing factor (ADF)/cofilin in actin "comet tails," using a minimal reconstituted system with nucleation-promoting factor (NPF)-coated beads. The Arp2/3 complex concentrates at nucleation sites near the beads as well as in the first actin shell. CP colocalizes with actin and is homogeneously distributed throughout the comet tail; it serves to constrain the spatial distribution of ATP/ADP-P(i) filament zones to areas near the bead. The association of ADF/cofilin with the actin network is therefore governed by kinetics of actin assembly, actin nucleotide state, and CP binding. A kinetic simulation accurately validates these observations. Following its binding to the actin networks, ADF/cofilin is able to break up the dense actin filament array of a comet tail. Stochastic severing by ADF/cofilin loosens the tight entanglement of actin filaments inside the comet tail and facilitates turnover through the macroscopic release of large portions of the aged actin network.

  8. Bone Turnover Markers in the Diagnosis and Monitoring of Metabolic Bone Disease.

    Science.gov (United States)

    Greenblatt, Matthew B; Tsai, Joy N; Wein, Marc N

    2017-02-01

    Disorders of bone metabolism, most notably osteoporosis, are highly prevalent and predispose to fractures, causing high patient morbidity and mortality. Diagnosis and monitoring of bone metabolic defects can present a major challenge as these disorders are largely asymptomatic and radiographic measures of bone mass respond slowly to changes in bone physiology. Bone turnover markers (BTMs) are a series of protein or protein derivative biomarkers released during bone remodeling by osteoblasts or osteoclasts. BTMs can offer prognostic information on fracture risk that supplements radiographic measures of bone mass, but testing using BTMs has to take into account the large number of preanalytic factors and comorbid clinical conditions influencing BTM levels. BTMs respond rapidly to changes in bone physiology, therefore, they have utility in determining patient response to and compliance with therapies for osteoporosis. BTMs are a useful adjunct for the diagnosis and therapeutic monitoring of bone metabolic disorders, but their use has to be tempered by the known limitations in their clinical utility and preanalytic variables complicating interpretation. © 2016 American Association for Clinical Chemistry.

  9. The right friends in the right places: Understanding network structure as a predictor of voluntary turnover.

    Science.gov (United States)

    Ballinger, Gary A; Cross, Rob; Holtom, Brooks C

    2016-04-01

    Research examining the relationship between social networks and employee retention has focused almost exclusively on the number of direct links and generally found that having more ties decreases the likelihood of turnover. The present research moves beyond simple measures of network centrality to investigate the relationship between 2 additional, and theoretically distinct, facets of social capital and voluntary turnover. In 2 organizations, we found consistent evidence of a negative relationship between reputation, as measured by relationships with highly sought-out others (incoming eigenvector centrality) and voluntary turnover. Further, we found that the negative relationship between brokerage (structural holes) and turnover is significant, but only for higher-level employees. The theoretical and practical implications of expanding the suite of social capital measures to understand voluntary turnover are discussed. (c) 2016 APA, all rights reserved).

  10. Roles of perceived exchange quality and organisational identification in predicting turnover intention

    Directory of Open Access Journals (Sweden)

    Manish Kumar

    2012-03-01

    Full Text Available This paper explores whether the perceived quality of the leader–member exchange and the general environment of exchange could predict turnover intention. It further examines the role of organisational identification as an explanatory variable mediating between exchange relationships and turnover intention. The authors used three-step hierarchical linear regressions on a data set collected in two time waves. The results supported the mediating role of organisational identification for the leader–member exchange and turnover intention relationship as well as the general environment of exchange and turnover intention relationship. Moreover, as was expected, the general exchange quality had a greater impact on organisational identification compared to the leader–member exchange quality. However, the findings did not confirm the expected trend in the case of two exchange variables predicting turnover intention.

  11. The effects of autonomy and empowerment on employee turnover: test of a multilevel model in teams.

    Science.gov (United States)

    Liu, Dong; Zhang, Shu; Wang, Lei; Lee, Thomas W

    2011-11-01

    Extending research on voluntary turnover in the team setting, this study adopts a multilevel self-determination theoretical approach to examine the unique roles of individual and social-contextual motivational precursors, autonomy orientation and autonomy support, in reducing team member voluntary turnover. Analysis of multilevel time-lagged data collected from 817 employees on 115 teams indicates that psychological empowerment mediates the main effect of autonomy orientation and the interactive effect of autonomy support and its differentiation on a team member's voluntary turnover. The findings have meaningful implications for the turnover and self-determination literatures as well as for managers who endeavor to prevent voluntary turnover in teams. (c) 2011 APA, all rights reserved.

  12. The relationship between family-to-work conflict of employee and co-workers' turnover intention

    Directory of Open Access Journals (Sweden)

    Tavakol Sharafi

    2012-01-01

    Full Text Available Previous studies have convincingly shown that employees' family lives can affect their work outcomes. We investigate whether family-to-work conflict (FWC experienced by the employee also affects the turnover intention of a co-worker. We predict that the employee's FWC has an effect on the co-worker's turnover intention through the crossover of positive and negative work attitudes. Using a sample of 154 co-worker dyads, we found that the employee FWC was positively related to co-worker turnover intention through the crossover of (reduced work engagement. Results show that family matters at work, affecting employee. In addition, employee's job engagement was positively related to his (her co-worker job engagement and it was negatively related co-worker turnover intention and employee's FWC was not positively related to co-worker turnover intention trough the crossover of (reduced feelings of engagement.

  13. Antecedents and consequence of employee turnover intention: Empirical evidence from Ghana

    Directory of Open Access Journals (Sweden)

    Michael A. Gyensare

    2015-08-01

    Full Text Available Guided by the theory of reasoned action, this study found support for the hypothesized inverse relationship between work-related factors and employee turnover intention on the one hand, and turnover intention and perceptions of accountable absence legitimacy on the other hand. Specifically, the higher employees’ turnover intent, the lower their perceptions about the accountability of their absence behavior and vice versa. The findings highlight the need to consider turnover intention as a salient construct that plays a dual role, first as a consequence variable to job satisfaction, affective and normative commitments, and next as an antecedent to accountable absence legitimacy in the workplace. The article concludes with a discussion on the significance of lessening employee turnover intent as a means of mitigating the perceptions of absence legitimacy in the workplace.

  14. The physical origins of rapid soil CO2 release following wetting

    Science.gov (United States)

    Schymanski, Stanislaus; Grahm, Lina; Or, Dani

    2017-04-01

    A rainfall event after an extended dry period is known to produce large spikes in CO2 release from soil, a phenomenon referred to as the "Birch effect". The Birch effect is commonly attributed to biological factors, such as the rapid activation of dormant microbial populations and stimulation of soil organic carbon turnover. Evidence suggests that CO2 emissions set in at time scales too short for microbial activation and growth (seconds to minutes after onset of wetting). We conducted controlled wetting experiments on sterilized soil in the lab showing CO2 efflux dynamics that are consistent in magnitude with those reported in field studies (up to 4 mmol m-2 s-1 per mm of precipitation). The explanation proposed is purely physical, involving desorption of CO2 from soil surfaces as it is replaced by the more polar water during wetting. We present experimental results and a CO2 adsorption and desorption model that lend credence to the notion that a large fraction of the early soil CO2 emission during wetting (minutes to an hour) is associated with physical processes independent of microbial activity. This suggests that a significant amount of atmospheric CO2 becomes bound to soil surfaces during dry seasons and is rapidly released at the onset of wet seasons world-wide, irrespective of the soil organic carbon cycle.

  15. Correlation of resource plays and biodiversity patterns: accumulation of organic-rich shale tracks taxonomic turnover

    Science.gov (United States)

    Eoff, Jennifer D.

    2012-01-01

    Similar paleogeographic and paleotectonic settings characterize most self-sourced shale hydrocarbon plays. Their deposition occurred within similar orders of magnitude of eustatic events and during geologic periods characterized by “warm” (or transitional) climates and calcitic seas. In addition, the stratigraphic occurrence of shale plays parallels certain historical patterns of marine metazoan biodiversity. Such strong agreement among several correlation tools elucidates why these resources may be limited to discrete intervals of geological time. Correlation of self-sourced shale with biodiversity trends indicates that the factors controlling the deposition of marine organic matter may not be independent of those that induced taxonomic turnover. Paleoecological changes promoted accumulation and preservation of Type II kerogen. Deposition of self-sourced shale appears to correspond to reductions in absolute biodiversity and declining percentages of bioturbating taxa, with concomitant increases in proportions of pelagic taxa relative to infaunal and epifaunal organisms. Whereas upwelling and anoxia may have contributed to the deposition of kerogen in source rocks throughout much of the sedimentary record, diminished consumption of biomass by benthic metazoans likely augmented the preservation of organic carbon during deposition of this shale type. Rapid tectonic-plate reconfiguration induced coeval events, creating basins with sufficiently high rates of accommodation creation necessary to preserve additional organic material accumulating as the heterotrophic benthos suffered in response to rapidly changing environments. Combining sea-level curves, paleogeography, climate, and seawater chemistry provides a first-order approximation of the distribution of potential self-sourced shale in the geologic record. A model that predicts the stratigraphic distribution of self-sourced-shale deposition can aid in exploration of continuous hydrocarbon accumulations in self

  16. Paleocene floral diversities and turnover events in eastern North America and their relation to diversity models

    Science.gov (United States)

    Frederiksen, N.O.

    1994-01-01

    This paper uses angiosperm pollen taxon turnover (first and last appearance) and diversity events as metrics to describe the Paleocene floral history of the eastern Gulf Coast; data are from 64 samples and 67 angiosperm pollen taxa. Angiosperm pollen diversity was very low at the beginning of the Paleocene, rose slowly and then somewhat more rapidly to a maximum for the epoch in the middle of the late Paleoceneas a result of the maximum in rate of first appearances during the late early Paleocene and earliest late Paleocene. Diversity then dropped very rapidly at or near the end of the epoch as the rate of last appearances reached its maximum, resulting in the Terminal Paleocene Extinction Event. The latest Paleocene diversity decline coincided with an increase in mean annual temperature and probably in rainfall, representing the beginning of the climatic maximum for the Tertiary which characterized the early Eocene. The increase in diversity of early Paleocene floras in the eastern Gulf Coast resulted from exploitation of unfilled ecospace originating from (1) low regional diversity following the Terminal Cretaceous Extinction Event, and (2) creation of many new niches during the Paleocene, resulting, according to megafloral evidence, from a change to a new vegetation type (multistratal tropical rainforest) brought about by an increase in rainfall. The slow rate of recovery of earliest Paleocene angiosperm diversity in the eastern Gulf Coast may be explained in part by the diversity-dependence model of Carr and Kitchell (1980). However, additional factors may have contributed to the slow recovery: (1) the adverse terminal Cretaceous climates may have extended into the early Paleocene, (2) the initial Paleocene environment of the eastern Gulf Coast may have contained relatively few niches, (3) some earliest Paleocene angiosperms, particularly trees, may have had inherently poor capabilities for rapid evolution, and (4) there was a lack of significant immigration of

  17. Timescales of carbon turnover in soils with mixed crystalline mineralogies

    Science.gov (United States)

    Khomo, Lesego; Trumbore, Susan; Bern, Carleton R.; Chadwick, Oliver A.

    2017-01-01

    Organic matter-mineral associations stabilize much of the carbon (C) stored globally in soils. Metastable short-range-order (SRO) minerals such as allophane and ferrihydrite provide one mechanism for long-term stabilization of organic matter in young soil. However, in soils with few SRO minerals and a predominance of crystalline aluminosilicate or Fe (and Al) oxyhydroxide, C turnover should be governed by chemisorption with those minerals. Here, we correlate mineral composition from soils containing small amounts of SRO minerals with mean turnover time (TT) of C estimated from radiocarbon (14C) in bulk soil, free light fraction and mineral-associated organic matter. We varied the mineral amount and composition by sampling ancient soils formed on different lithologies in arid to subhumid climates in Kruger National Park (KNP), South Africa. Mineral contents in bulk soils were assessed using chemical extractions to quantify Fe oxyhydroxides and SRO minerals. Because of our interest in the role of silicate clay mineralogy, particularly smectite (2 : 1) and kaolinite (1 : 1), we separately quantified the mineralogy of the clay-sized fraction using X-ray diffraction (XRD) and measured 14C on the same fraction. Density separation demonstrated that mineral associated C accounted for 40-70 % of bulk soil organic C in A and B1 horizons for granite, nephelinite and arid-zone gabbro soils, and > 80 % in other soils. Organic matter strongly associated with the isolated clay-sized fraction represented only 9-47 % of the bulk soil C. The mean TT of C strongly associated with the clay-sized fraction increased with the amount of smectite (2 : 1 clays); in samples with > 40 % smectite it averaged 1020 ± 460 years. The C not strongly associated with clay-sized minerals, including a combination of low-density C, the C associated with minerals of sizes between 2 µm and 2 cm (including Fe oxyhydroxides as coatings), and C removed from clay-sized material by 2 % hydrogen peroxide had

  18. Timescales of carbon turnover in soils with mixed crystalline mineralogies

    Science.gov (United States)

    Khomo, Lesego; Trumbore, Susan E.; Bern, Carleton R.; Chadwick, Oliver A.

    2017-01-01

    Organic matter–mineral associations stabilize much of the carbon (C) stored globally in soils. Metastable short-range-order (SRO) minerals such as allophane and ferrihydrite provide one mechanism for long-term stabilization of organic matter in young soil. However, in soils with few SRO minerals and a predominance of crystalline aluminosilicate or Fe (and Al) oxyhydroxide, C turnover should be governed by chemisorption with those minerals. Here, we correlate mineral composition from soils containing small amounts of SRO minerals with mean turnover time (TT) of C estimated from radiocarbon (14C) in bulk soil, free light fraction and mineral-associated organic matter. We varied the mineral amount and composition by sampling ancient soils formed on different lithologies in arid to subhumid climates in Kruger National Park (KNP), South Africa. Mineral contents in bulk soils were assessed using chemical extractions to quantify Fe oxyhydroxides and SRO minerals. Because of our interest in the role of silicate clay mineralogy, particularly smectite (2 : 1) and kaolinite (1 : 1), we separately quantified the mineralogy of the clay-sized fraction using X-ray diffraction (XRD) and measured 14C on the same fraction. Density separation demonstrated that mineral associated C accounted for 40–70 % of bulk soil organic C in A and B1 horizons for granite, nephelinite and arid-zone gabbro soils, and > 80 % in other soils. Organic matter strongly associated with the isolated clay-sized fraction represented only 9–47 % of the bulk soil C. The mean TT of C strongly associated with the clay-sized fraction increased with the amount of smectite (2 : 1 clays); in samples with > 40 % smectite it averaged 1020 ± 460 years. The C not strongly associated with clay-sized minerals, including a combination of low-density C, the C associated with minerals of sizes between 2 µm and 2 cm (including Fe oxyhydroxides as coatings), and C removed from clay

  19. Comparison of whole calvarial bones and long bones during early growth in rats. II. Turnover of calcified and uncalcified collagen masses.

    Science.gov (United States)

    Klein, L; Zika, J M

    1976-04-20

    The increase of total collagen and its destruction were compared for whole calvaria and long bones from young growing rats prelabeled in utero with 3H-L-proline. Rats were compared from birth to 16 weeks of age. Long bones and calvaria were isolated as intact anatomical units for autoradiography or separated by collagenase into calified and uncalcified collagens. Autoradiography using 14C-L-proline demonstrated eccentric modeling of bone collagen. With growth the mass of calcified collagen (bone) increased rapidly in calvaria and long bones. A similar increase in the mass of uncalcified collagen (mainly cartilage) occured in the long bones; a very small increase occurred in the fibrous tissue of calvaria. Total and specific radioactivities of collagens at each age were compared to that present at birth. With growth remodeling an almost complete loss of pre-existing radioactive collagen occurred from uncalcified fibrous tissue of calvaria as compared to a smaller but substantial loss from the uncalcified cartilage of long bones. A marked loss of calcifed collagen occurred in long bones as compared to a smaller loss from calvarial bones. The istopic data indicate a large turnover of fibrous tissue (type I collagen) with growth remodeling as compared to a smaller turnover of bone (calcified, type I collagen) and cartilage (typc I collagen). The turnover rate of skeletal collagens depends upon whether the collagen is calcified or not, and not upon the type of collagen.

  20. Further Clarifying Proximal Withdrawal States and the Turnover Criterion Space: Comment on Hom, Mitchell, Lee, and Griffeth (2012)

    Science.gov (United States)

    Maertz, Carl P., Jr.

    2012-01-01

    In "Reviewing Employee Turnover: Focusing on Proximal Withdrawal States and an Expanded Criterion," Hom, Mitchell, Lee, and Griffeth (2012) brought together many of the most important content and process factors in the employee turnover literature. In this paper, I attempt to clarify the true contributions of this framework for the turnover area…

  1. Listening to the Voices of Children in Foster Care: Youths Speak out about Child Welfare Workforce Turnover and Selection

    Science.gov (United States)

    Strolin-Goltzman, Jessica; Kollar, Sharon; Trinkle, Joanne

    2010-01-01

    Child welfare workforce turnover rates across private and public child welfare agencies are concerning. Although research about the causes of child welfare workforce turnover has been plentiful, empirical studies on the effects of turnover on child outcomes are sparse. Furthermore, the voices and experiences of youths within the system have been…

  2. Microbial communities mediating algal detritus turnover under anaerobic conditions

    Directory of Open Access Journals (Sweden)

    Jessica M. Morrison

    2017-01-01

    Full Text Available Background Algae encompass a wide array of photosynthetic organisms that are ubiquitously distributed in aquatic and terrestrial habitats. Algal species often bloom in aquatic ecosystems, providing a significant autochthonous carbon input to the deeper anoxic layers in stratified water bodies. In addition, various algal species have been touted as promising candidates for anaerobic biogas production from biomass. Surprisingly, in spite of its ecological and economic relevance, the microbial community involved in algal detritus turnover under anaerobic conditions remains largely unexplored. Results Here, we characterized the microbial communities mediating the degradation of Chlorella vulgaris (Chlorophyta, Chara sp. strain IWP1 (Charophyceae, and kelp Ascophyllum nodosum (phylum Phaeophyceae, using sediments from an anaerobic spring (Zodlteone spring, OK; ZDT, sludge from a secondary digester in a local wastewater treatment plant (Stillwater, OK; WWT, and deeper anoxic layers from a seasonally stratified lake (Grand Lake O’ the Cherokees, OK; GL as inoculum sources. Within all enrichments, the majority of algal biomass was metabolized within 13–16 weeks, and the process was accompanied by an increase in cell numbers and a decrease in community diversity. Community surveys based on the V4 region of the 16S rRNA gene identified different lineages belonging to the phyla Bacteroidetes, Proteobacteria (alpha, delta, gamma, and epsilon classes, Spirochaetes, and Firmicutes that were selectively abundant under various substrate and inoculum conditions. Within all kelp enrichments, the microbial communities structures at the conclusion of the experiment were highly similar regardless of the enrichment source, and were dominated by the genus Clostridium, or family Veillonellaceae within the Firmicutes. In all other enrichments the final microbial community was dependent on the inoculum source, rather than the type of algae utilized as substrate

  3. Microbial communities mediating algal detritus turnover under anaerobic conditions

    Science.gov (United States)

    Morrison, Jessica M.; Murphy, Chelsea L.; Baker, Kristina; Zamor, Richard M.; Nikolai, Steve J.; Wilder, Shawn; Elshahed, Mostafa S.

    2017-01-01

    Background Algae encompass a wide array of photosynthetic organisms that are ubiquitously distributed in aquatic and terrestrial habitats. Algal species often bloom in aquatic ecosystems, providing a significant autochthonous carbon input to the deeper anoxic layers in stratified water bodies. In addition, various algal species have been touted as promising candidates for anaerobic biogas production from biomass. Surprisingly, in spite of its ecological and economic relevance, the microbial community involved in algal detritus turnover under anaerobic conditions remains largely unexplored. Results Here, we characterized the microbial communities mediating the degradation of Chlorella vulgaris (Chlorophyta), Chara sp. strain IWP1 (Charophyceae), and kelp Ascophyllum nodosum (phylum Phaeophyceae), using sediments from an anaerobic spring (Zodlteone spring, OK; ZDT), sludge from a secondary digester in a local wastewater treatment plant (Stillwater, OK; WWT), and deeper anoxic layers from a seasonally stratified lake (Grand Lake O’ the Cherokees, OK; GL) as inoculum sources. Within all enrichments, the majority of algal biomass was metabolized within 13–16 weeks, and the process was accompanied by an increase in cell numbers and a decrease in community diversity. Community surveys based on the V4 region of the 16S rRNA gene identified different lineages belonging to the phyla Bacteroidetes, Proteobacteria (alpha, delta, gamma, and epsilon classes), Spirochaetes, and Firmicutes that were selectively abundant under various substrate and inoculum conditions. Within all kelp enrichments, the microbial communities structures at the conclusion of the experiment were highly similar regardless of the enrichment source, and were dominated by the genus Clostridium, or family Veillonellaceae within the Firmicutes. In all other enrichments the final microbial community was dependent on the inoculum source, rather than the type of algae utilized as substrate. Lineages enriched

  4. On the controlling mechanism of the upper turnover states in the NTC regime

    KAUST Repository

    Ji, Weiqi

    2015-12-18

    Using n-butane, n-heptane and iso-octane as representative fuels exhibiting NTC (negative temperature coefficient) behavior, comprehensive computational studies with detailed mechanisms and theoretical analysis were performed to investigate the upper stationary point, denoted as turnover states, on the NTC curve near the higher temperature regime, where the ignition delay τ exhibits a local maximum. It is found that the global behavior of the turnover states exhibits distinctive thermodynamic and kinetic characteristics under different pressures, in that the ignition delay at the turnover states shows an Arrhenius dependence on the temperature T and an approximate inverse quadratic power law dependence on the pressure P. These global behaviors imply that the temperature and pressure of the turnover states are not independent and can be correlated by Arrhenius dependence, as ln P ∝ 1/T. Further theoretical analyses demonstrate that such turnover states result from the competition between the low-temperature chain branching reactions and the decomposition of the intermediate species, and therefore correspond to a critical value, α, of the ratio of OH production from low-temperature chemistry. In addition, the ignition delay at the turnover state can be well correlated by the analytical expression derived by Peters et al., with the further demonstration that the pressure dependence of the turnover ignition delay mainly result from the H2O2 decomposition reaction. Comparison of the present results with the literature experimental data of n-heptane ignition delay time shows very good agreement.

  5. The mediating effect of emotional intelligence between emotional labour, job stress, burnout and nurses' turnover intention.

    Science.gov (United States)

    Hong, Eunyoung; Lee, Young Sook

    2016-12-01

    This study was designed to construct and test the structural equation modelling on nurses' turnover intention including emotional labour, job stress, emotional intelligence and burnout in order to identify the mediating effect of emotional intelligence between those variables. Emotional labour, job stress and burnout increase turnover intention of nurses. However, emotional intelligence is negatively correlated with emotional labour and reduces job stress, burnout and turnover intention. Structural equation modelling was used to analyse the goodness of fit of the hypothetical model of nurses' turnover intention. Research data were collected via questionnaires from 4 to 22 August 2014 and analysed using SPSS version 18.0 and AMOS version 20.0. The model fit indices for the hypothetical model were suitable for recommended. Emotional intelligence has decreasing effect on turnover intention through burnout, although its direct effect on turnover intention is not significant. Emotional intelligence has mediation effect between emotional labour and burnout. This study's results suggest that increasing emotional intelligence might critically decrease nurses' turnover intention by reducing the effect of emotional labour on burnout. © 2016 John Wiley & Sons Australia, Ltd.

  6. Effects of role stress on nurses' turnover intentions: The mediating effects of organizational commitment and burnout.

    Science.gov (United States)

    Han, Sang-Sook; Han, Jeong-Won; An, Young-Suk; Lim, So-Hee

    2015-10-01

    This paper was designed to extend the extant research regarding factors related to nurses' turnover intentions. This survey-based study was based on a path analysis designed to verify a hypothesized causal model involving nurses' role stress, organizational commitment, turnover intentions, and burnout. This study distributed 500 questionnaires to nurses in general hospitals with more than 500 beds located in Seoul, Korea, during 16-30 April 2012. Role conflict, an underlying factor in role stress, had no significant effect on role stress, but the results showed that role ambiguity reduced organizational commitment. On the other hand, role conflict and role ambiguity increased the level of burnout. Organizational commitment reduced turnover intentions, and burnout increased turnover intentions. Role conflict and role ambiguity had no direct effect on turnover intentions, but they had indirect effects on organizational commitment and burnout. To reduce nurses' turnover rate, this study recommends developing plans to improve their organizational commitment because it mediates role stress and turnover intention. © 2014 The Authors. Japan Journal of Nursing Science © 2014 Japan Academy of Nursing Science.

  7. Turnover of nonessential fatty acids in cardiolipin from the rat heart

    Science.gov (United States)

    Wahjudi, Paulin N.; K. Yee, Jennifer; Martinez, Steven R.; Zhang, Jin; Teitell, Michael; Nikolaenko, Liana; Swerdloff, Ronald; Wang, Christina; Lee, W. N. Paul

    2011-01-01

    Cardiolipin (CL) is a unique phospholipid (PL) found in the mitochondria of mammalian cells. CL remodeling is accompanied by turnover of its fatty acid acyl groups. Abnormalities in CL remodeling have been found in Barth's syndrome, diabetes, and obesity. The objective of this study was to determine nonessential fatty acid turnover in CL and phosphatidylethanolamine (PE) in the rat heart in vivo. Sprague-Dawley rats were fed either a regular chow or a high-fat diet for 15 weeks, and consumed 6% deuterium-enriched drinking water as a tracer for 14 days. CL and PE were extracted from cardiac tissue and isolated by TLC. Fatty acids from CL, PE, and plasma were analyzed by GC/MS for deuterium incorporation. Results showed oleate and vaccenate turnover were the highest in CL whereas palmitate and stearate turnover were low. Among the nonessential fatty acids in PE, turnover of stearate and vaccenate were the highest. The high turnover rate in vaccenate was unexpected, because vaccenate previously had no known metabolic or physiologic function. In conclusion, the similarly high turnover rates of both oleate and vaccenate readily suggest that remodeling is an important functional aspect of PL metabolism in CL. PMID:21957203

  8. MHC class II protein turnover in vivo and its relevance for autoimmunity in nonobese diabetic mice

    Directory of Open Access Journals (Sweden)

    Robert eBusch

    2013-11-01

    Full Text Available MHCII proteins are loaded with endosomal peptides and reside at the surface of antigen-presenting cells (APCs for a time before being degraded. In vitro, MHCII protein levels and turnover are affected by peptide loading and by rates of ubiquitin-dependent internalization from the cell surface, which is in turn affected by APC type and activation state. Prior work suggested that fast turnover of disease-associated MHCII alleles may contribute to autoimmunity. We recently developed novel stable isotope tracer techniques to test this hypothesis in vivo. In nonobese diabetic (NOD mice, a model of type 1 diabetes (T1D, MHCII turnover was affected by APC type, but unaffected by disease-associated structural polymorphism. Differences in MHCII turnover were observed between NOD colonies with high and low T1D incidence, but fast turnover was dispensable for autoimmunity. Moreover, NOD mice with gene knockouts of peptide loading cofactors do not develop T1D. Thus, fast turnover does not appear pathogenic, and conventional antigen presentation is critical for autoimmunity in NOD mice. However, shared environmental factors may underpin colony differences in MHCII protein turnover, immune regulation, and pathogenesis.

  9. Turnover intentions in a call center: The role of emotional dissonance, job resources, and job satisfaction.

    Science.gov (United States)

    Zito, Margherita; Emanuel, Federica; Molino, Monica; Cortese, Claudio Giovanni; Ghislieri, Chiara; Colombo, Lara

    2018-01-01

    Turnover intentions refer to employees' intent to leave the organization and, within call centers, it can be influenced by factors such as relational variables or the perception of the quality of working life, which can be affected by emotional dissonance. This specific job demand to express emotions not felt is peculiar in call centers, and can influence job satisfaction and turnover intentions, a crucial problem among these working contexts. This study aims to detect, within the theoretical framework of the Job Demands-Resources Model, the role of emotional dissonance (job demand), and two resources, job autonomy and supervisors' support, in the perception of job satisfaction and turnover intentions among an Italian call center. The study involved 318 call center agents of an Italian Telecommunication Company. Data analysis first performed descriptive statistics through SPSS 22. A path analysis was then performed through LISREL 8.72 and tested both direct and indirect effects. Results suggest the role of resources in fostering job satisfaction and in decreasing turnover intentions. Emotional dissonance reveals a negative relation with job satisfaction and a positive relation with turnover. Moreover, job satisfaction is negatively related with turnover and mediates the relationship between job resources and turnover. This study contributes to extend the knowledge about the variables influencing turnover intentions, a crucial problem among call centers. Moreover, the study identifies theoretical considerations and practical implications to promote well-being among call center employees. To foster job satisfaction and reduce turnover intentions, in fact, it is important to make resources available, but also to offer specific training programs to make employees and supervisors aware about the consequences of emotional dissonance.

  10. Use of ABC–XYZ–analysis in cost management of the cargo turnover in transport logistics

    OpenAIRE

    Chukurna O.; Davydova A.

    2017-01-01

    This article focuses on the relevance of the use of ABC–XYZ–analysis in the management of cargo turnover costs in the implementation of transport and logistics operations. It proposed by using the ABC analysis to rank suppliers or customers of freight turnover and the cost of each logistics operation (or profitability of the logistics services). On the basis of the received data to optimise logistics costs. It is proposed to use the XYZ–analysis to predict the volume of cargo turnover and a l...

  11. The collagen turnover profile is altered in patients with inguinal and incisional hernia

    DEFF Research Database (Denmark)

    Henriksen, Nadia A; Mortensen, Joachim H; Sorensen, Lars T

    2015-01-01

    in the interstitial matrix (types I, III, and V collagens) and in the basement membrane (type IV collagen). MATERIAL AND METHODS: Patients with 3 different types of hernias were included: Primary unilateral inguinal hernia (n = 17), multiple hernias defined as ≥3 hernias (n = 21), and incisional hernia (n = 25......, and C4M) were measured in serum by validated, solid-phase competitive assays. RESULTS: In inguinal hernia patients, the turnover of the interstitial matrix collagens type III (P ... turnover profile of type IV collagens may predict the presence of inguinal and incisional hernia. Regulation of type IV collagen turnover may be crucial for hernia development....

  12. Radiocarbon dating reveals minimal collagen turnover in both healthy and osteoarthritic human cartilage

    DEFF Research Database (Denmark)

    Heinemeier, Katja M; Schjerling, Peter; Heinemeier, Jan

    2016-01-01

    The poor regenerative capacity of articular cartilage presents a major clinical challenge and may relate to a limited turnover of the cartilage collagen matrix. However, the collagen turnover rate during life is not clear, and it is debated whether osteoarthritis (OA) can influence it. Using......, no replacement of the collagen matrix happened after skeletal maturity and that neither OA nor tissue damage, per se, influenced collagen turnover. Regional differences in (14)C content across the joint surface showed that cartilage collagen located centrally on the joint surface is formed several years earlier...

  13. Menguji Konsistensi Korelasi Job Satisfaction dengan Intensi Turnover: Studi Meta-Analisis

    Directory of Open Access Journals (Sweden)

    Ferdinand - Hindiarto

    2017-12-01

    Full Text Available Abstract This study examines the correlation between job satisfaction and turnover intention from various studies in 2009-2016, with meta-analysis method. The used samples consist of 25 studies from 21 research journal which is found by searching on online database: ProQuest, EBSCO and EmeraldInsight via www.lib.ugm.ac.id. Analysis conduct on 2 artefacts, correction on error sampling and on error measuring. Result of the study shows that correlation between job satisfaction and turnover intention in 1st artefact is -0,46 and in 2nd artefact is -0,56. Keyword: meta-analysis, job satisfaction, turnover intention

  14. Improving operating room turnover time: a systems based approach.

    Science.gov (United States)

    Bhatt, Ankeet S; Carlson, Grant W; Deckers, Peter J

    2014-12-01

    Operating room (OR) turnover time (TT) has a broad and significant impact on hospital administrators, providers, staff and patients. Our objective was to identify current problems in TT management and implement a consistent, reproducible process to reduce average TT and process variability. Initial observations of TT were made to document the existing process at a 511 bed, 24 OR, academic medical center. Three control groups, including one consisting of Orthopedic and Vascular Surgery, were used to limit potential confounders such as case acuity/duration and equipment needs. A redesigned process based on observed issues, focusing on a horizontally structured, systems-based approach has three major interventions: developing consistent criteria for OR readiness, utilizing parallel processing for patient and room readiness, and enhancing perioperative communication. Process redesign was implemented in Orthopedics and Vascular Surgery. Comparisons of mean and standard deviation of TT were made using an independent 2-tailed t-test. Using all surgical specialties as controls (n = 237), mean TT (hh:mm:ss) was reduced by 0:20:48 min (95 % CI, 0:10:46-0:30:50), from 0:44:23 to 0:23:25, a 46.9 % reduction. Standard deviation of TT was reduced by 0:10:32 min, from 0:16:24 to 0:05:52 and frequency of TT≥30 min was reduced from 72.5to 11.7 %. P systems-based focus should drive OR TT design.

  15. Degradation of asialoprothrombin and its relevance to prothrombin turnover

    Energy Technology Data Exchange (ETDEWEB)

    Vostal, J.G.

    1986-01-01

    As a part of their turnover, serum glycoproteins have been thought to be cleared from plasma and degraded after an initial conversion to an asialogylcoprotein intermediate. The authors have examined this possibility with the plasma protein prothrombin. Bovine prothrombin and its asialo derivative were prepared and radioiodinated by conventional methods. In vivo plasma half lives of trichloroacetic acid (TCA) precipitable radioactivity were estimated in heparinized and anesthetized rats following and injection of the individual proteins into the femoral vein. For prothrombin, the half life was 3.2 hours with very little plasma TCA soluble radioactive products formed over 3 hours. Asialo-prothrombin's half life was only 1.1 minutes with soluble radioactive material increasing greatly during the initial 30 minutes. Simultaneous administration of competing doses of asialofetuin greatly increased the apparent half life of asialoprothrombin. The uptake and the release of TCA soluble radioactivity from liver was also delayed. Studies with isolated hepatocytes further demonstrated that asialoprothrombin was taken up by the cells and eventually degraded in the lysosomes. However, single or multiple injections of the highest dose of asialofetuin had no effect on /sup 125/I-prothrombin half life plasma soluble radioactivity or accumulation in the liver. The data indicate that while exogenously administered asialoprothrombin is apparently cleared from circulation by a hepatic asialoglycoprotein receptor, prothrombin, even though accumulated by the liver, is not.

  16. Bone growth and turnover in progesterone receptor knockout mice.

    Energy Technology Data Exchange (ETDEWEB)

    Rickard, David J.; Iwaniec, Urszula T.; Evans, Glenda; Hefferan, Theresa E.; Hunter, Jaime C.; Waters, Katrina M.; Lydon, John P.; O' Malley, Bert W.; Khosla, Sundeep; Spelsberg, Thomas C.; Turner, Russell T.

    2008-05-01

    The role of progesterone receptor (PR) signaling in skeletal metabolism is controversial. To address whether signaling through the PR is necessary for normal bone growth and turnover, we performed histomorphometric and mCT analyses of bone from homozygous female PR knockout (PRKO) mice at 6, 12, and 26 weeks of age. These mice possess a null mutation of the PR locus, which blocks the gene expression of A and B isoforms of PR. Body weight gain, uterine weight gain and tibia longitudinal bone growth was normal in PRKO mice. In contrast, total and cortical bone mass were increased in long bones of post-pubertal (12 and 26-week-old) PRKO mice, whereas cancellous bone mass was normal in the tibia but increased in the humerus. The striking 57% decrease in cancellous bone from the proximal tibia metaphysis which occurred between 6 and 26 weeks in WT mice was abolished in PRKO mice. The improved bone balance in aging PRKO mice was associated with elevated bone formation and a tendency toward reduced osteoclast perimeter. Taken together, these findings suggest that PR signaling in mice attenuates the accumulation of cortical bone mass during adolescence and is required for early age-related loss of cancellous bone.

  17. Employee Turnover and Knowledge Management in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Lucie Vnoučková

    2015-01-01

    Full Text Available Knowledge economy regards employee knowledge as a most important asset. It is a priority task to ensure systematic knowledge continuity of those employees who are the holders of critical knowledge. The aim of the article is to analyse the causes of mobility of knowledge workers and categorise types of employees and mobility according to the future development of an employee’s career. The research areas, i.e. ensuring knowledge continuity and employee turnover were analysed based on the premise of significant relation between those two areas. The data were collected in organizations in the Czech Republic. Surveys were drawn across sectors to ensure representativeness of the outcomes. The outputs revealed two basic approaches to maintaining knowledge inside organizations. Employees can be divided into knowledge workers and remainder, who seek only security. A knowledge worker who decides to transfer is not motivated by the amount of salary (they do not mind a lower level of remuneration; on the contrary they suffer due to an unclear vision on the part of the organization, where they used to work; they cannot stay in conditions where there is no possibility to participate on personal growth. Future research in this area should focus on the return of investments in the knowledge and employee learning, training and retention.

  18. Kindlin-1 regulates integrin dynamics and adhesion turnover.

    Science.gov (United States)

    Margadant, Coert; Kreft, Maaike; Zambruno, Giovanna; Sonnenberg, Arnoud

    2013-01-01

    Loss-of-function mutations in the gene encoding the integrin co-activator kindlin-1 cause Kindler syndrome. We report a novel kindlin-1-deficient keratinocyte cell line derived from a Kindler syndrome patient. Despite the expression of kindlin-2, the patient's cells display several hallmarks related to reduced function of β1 integrins, including abnormal cell morphology, cell adhesion, cell spreading, focal adhesion assembly, and cell migration. Defective cell adhesion was aggravated by kindlin-2 depletion, indicating that kindlin-2 can compensate to a certain extent for the loss of kindlin-1. Intriguingly, β1 at the cell-surface was aberrantly glycosylated in the patient's cells, and its expression was considerably reduced, both in cells in vitro and in the patient's epidermis. Reconstitution with wild-type kindlin-1 but not with a β1-binding defective mutant restored the aberrant β1 expression and glycosylation, and normalized cell morphology, adhesion, spreading, and migration. Furthermore, the expression of wild-type kindlin-1, but not of the integrin-binding-defective mutant, increased the stability of integrin-mediated cell-matrix adhesions and enhanced the redistribution of internalized integrins to the cell surface. Thus, these data uncover a role for kindlin-1 in the regulation of integrin trafficking and adhesion turnover.

  19. Kindlin-1 regulates integrin dynamics and adhesion turnover.

    Directory of Open Access Journals (Sweden)

    Coert Margadant

    Full Text Available Loss-of-function mutations in the gene encoding the integrin co-activator kindlin-1 cause Kindler syndrome. We report a novel kindlin-1-deficient keratinocyte cell line derived from a Kindler syndrome patient. Despite the expression of kindlin-2, the patient's cells display several hallmarks related to reduced function of β1 integrins, including abnormal cell morphology, cell adhesion, cell spreading, focal adhesion assembly, and cell migration. Defective cell adhesion was aggravated by kindlin-2 depletion, indicating that kindlin-2 can compensate to a certain extent for the loss of kindlin-1. Intriguingly, β1 at the cell-surface was aberrantly glycosylated in the patient's cells, and its expression was considerably reduced, both in cells in vitro and in the patient's epidermis. Reconstitution with wild-type kindlin-1 but not with a β1-binding defective mutant restored the aberrant β1 expression and glycosylation, and normalized cell morphology, adhesion, spreading, and migration. Furthermore, the expression of wild-type kindlin-1, but not of the integrin-binding-defective mutant, increased the stability of integrin-mediated cell-matrix adhesions and enhanced the redistribution of internalized integrins to the cell surface. Thus, these data uncover a role for kindlin-1 in the regulation of integrin trafficking and adhesion turnover.

  20. Increased hypothalamic serotonin turnover in inflammation-induced anorexia.

    Science.gov (United States)

    Dwarkasing, J T; Witkamp, R F; Boekschoten, M V; Ter Laak, M C; Heins, M S; van Norren, K

    2016-05-20

    Anorexia can occur as a serious complication of disease. Increasing evidence suggests that inflammation plays a major role, along with a hypothalamic dysregulation characterized by locally elevated serotonin levels. The present study was undertaken to further explore the connections between peripheral inflammation, anorexia and hypothalamic serotonin metabolism and signaling pathways. First, we investigated the response of two hypothalamic neuronal cell lines to TNFα, IL-6 and LPS. Next, we studied transcriptomic changes and serotonergic activity in the hypothalamus of mice after intraperitoneal injection with TNFα, IL-6 or a combination of TNFα and IL-6. In vitro, we showed that hypothalamic neurons responded to inflammatory mediators by releasing cytokines. This inflammatory response was associated with an increased serotonin release. Mice injected with TNFα and IL-6 showed decreased food intake, associated with altered expression of inflammation-related genes in the hypothalamus. In addition, hypothalamic serotonin turnover showed to be elevated in treated mice. Overall, our results underline that peripheral inflammation reaches the hypothalamus where it affects hypothalamic serotoninergic metabolism. These hypothalamic changes in serotonin pathways are associated with decreased food intake, providing evidence for a role of serotonin in inflammation-induced anorexia.

  1. Pancreatic enzyme synthesis and turnover in human subjects.

    Science.gov (United States)

    O'Keefe, S J; Bennet, W M; Zinsmeister, A R; Haymond, M W

    1994-05-01

    Animal studies have shown that pancreatic enzyme secretion is independent of enzyme synthesis. To investigate this relationship in humans, we have coinfused 14C-labeled leucine tracer with cholecystokinin octapeptide in nine healthy adults for 4 h and measured the rate of appearance of secreted and newly labeled enzymes in the duodenum. Enzyme secretion was well maintained throughout, but newly labeled enzymes only appeared in juice between 75 and 101 min (median time, 86 min), indicating that initial secretion was dependent on the release of zymogen stores and that the median production time for new enzymes was 86 min. Between 85 and 225 min there was a curvilinear increase in the enrichment of secreted enzymes with newly synthesized enzymes, suggesting a median turnover rate of zymogen stores of 29%/h (range 12-47%/h). In conclusion, our results suggest that in healthy humans, postprandial pancreatic enzyme secretion is maintained by the export of a large stored pool and is not rate limited by enzyme synthesis, since it takes approximately 86 min for newly synthesized enzymes to take part in the digestive process.

  2. Geographical variation in mutualistic networks: similarity, turnover and partner fidelity.

    Science.gov (United States)

    Trøjelsgaard, Kristian; Jordano, Pedro; Carstensen, Daniel W; Olesen, Jens M

    2015-03-07

    Although species and their interactions in unison represent biodiversity and all the ecological and evolutionary processes associated with life, biotic interactions have, contrary to species, rarely been integrated into the concepts of spatial β-diversity. Here, we examine β-diversity of ecological networks by using pollination networks sampled across the Canary Islands. We show that adjacent and distant communities are more and less similar, respectively, in their composition of plants, pollinators and interactions than expected from random distributions. We further show that replacement of species is the major driver of interaction turnover and that this contribution increases with distance. Finally, we quantify that species-specific partner compositions (here called partner fidelity) deviate from random partner use, but vary as a result of ecological and geographical variables. In particular, breakdown of partner fidelity was facilitated by increasing geographical distance, changing abundances and changing linkage levels, but was not related to the geographical distribution of the species. This highlights the importance of space when comparing communities of interacting species and may stimulate a rethinking of the spatial interpretation of interaction networks. Moreover, geographical interaction dynamics and its causes are important in our efforts to anticipate effects of large-scale changes, such as anthropogenic disturbances. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  3. TRENDS OF THE FACTORING TURNOVER IN INTERNATIONAL COMPARISONS

    Directory of Open Access Journals (Sweden)

    Éva DARABOS

    2017-05-01

    Full Text Available The factoring scheme was developed by the competition between the market operators and the need for the most favourable conditions of sale. The seller is constrained to provide loans on a broad scale therefore the seller may have liquidity problems. In cases of this kind, the seller can apply to a factoring company in order to access sources, instead of a bank loan. The factoring service has a price. Decision of the financial managers can largely contribute to choosing the appropriate funding form to retain the continuous liquidity situation of an enterprise. Aim of the article is to present the main tendencies of the factoring turnover in international comparisons, highlighting the characteristics of the financial service by its direction, sectorial distribution and customer size in Hungary. It has been estimated that the factoring financing approaches 10% of the short-term loan stocks of SMEs required from banks which indicates that the factoring is now far beyond the marginal financial service but it is an essential element of the short-term financing toolkit.

  4. Roles of stem cells in tissue turnover and radiation carcinogenesis.

    Science.gov (United States)

    Niwa, Ohtsura

    2010-12-01

    Radiation research has its foundation on the target and hit theories, which assume that the initial stochastic deposition of energy on a sensitive target in a cell determines the final biological outcome. This assumption is rather static in nature but forms the foundation of the linear no-threshold (LNT) model of radiation carcinogenesis. The stochastic treatment of radiation carcinogenesis by the LNT model enables easy calculation of radiation risk, and this has made the LNT model an indispensable tool for radiation protection. However, the LNT model sometimes fails to explain some of the biological and epidemiological data, and this suggests the need for insight into the mechanisms of radiation carcinogenesis. Recent studies have identified unique characteristics of the tissue stem cells and their roles in tissue turnover. In the present report, some important issues of radiation protection such as the risk of low-dose-rate exposures and in utero exposures are discussed in light of the recent advances of stem cell biology.

  5. A model of voluntary turnover among hospital CEOs.

    Science.gov (United States)

    Weil, P A; Kimball, P A

    1995-01-01

    This study examines factors contributing to hospital CEOs' voluntary decisions to leave their positions in 1990. Using a longitudinal design, we contrast 49 leavers with 1,362 stayers. We view turnover as influenced by both "push" factors that promote leaving (dissatisfaction with the position) and "hump" factors that need to be overcome (the cost of job change). Push factors giving rise to dissatisfaction include lower compensation, the predecessor's termination, and value incongruity between the CEO and the hospital. Testing the impact of key variables from Fiedler's contingency theory of leadership, we show that task-oriented leaders are relatively less satisfied when compared with relationship-oriented leaders. CEOs also express less satisfaction in low-situational control settings, a measure heavily influenced by perceived inadequate support from medical staff and subordinates. "Hump" factors that deterred leaving included family-related obstacles such as spouse's work or children's school, features mentioned most often by younger CEOs. The study suggests that boards should structure competitively paid positions with opportunities to generate support from the medical staff and subordinates. Recruiters for CEO positions are apprised of the importance of nonwork features in CEOs' willingness to consider new positions.

  6. Foliage litter turnover and earthworm populations in three beech forests of contrasting soil and vegetation types.

    Science.gov (United States)

    Staaf, H

    1987-04-01

    Leaf litter decomposition, levels of accumulated litter as well as the abundance and biomass of earthworms were measured in three mature beech forests in southern Sweden: one mor site, one poor mull site, and one rich mull site. The disappearance rate of beech litter, measured with litter bags, increased with increasing soil fertility. On the rich mull site, the disappearance rate was much higher than in the two other forests, due to the combined effects of higher earthworm activity, more favouable soil moisture conditions, and higher litter quality. Incubating the litter in finely meshed bags (1-mm mesh) to exclude macrofauna had a great effect on litter mass loss in the rich mull site, but it had only a minor effect in the other sites. Simultaneous incubations of local and transplanted leaf litter on the three study sites showed that the substrate quality of the litter increased in the order: mor site - poor mull site - rich mull site. Lignin, N, and P concentrations of the leaf litter failed to explain the observed differences in decomposition rates, and acid/base properties are suggested to be more important. Earthworm numbers per m(2) were 2.5 (1 species) in the mor, 40 (6 species) in the poor mull and 220 (9 species) in the rich mull forest. Soil chemical conditions, notably pH, were suggested as the main factors determining the inter-site differences in abundance and species composition of earthworms. The role of litter decomposition and earthworm activity in the accumulation of organic matter in the forest floor in different types of beech woodlands are discussed.

  7. ENHANCED ORGANIC MATTER REMINERALIZATION AND NUTRIENT TURNOVER BY POPULATIONS OF BURROWING SHRIMP IN YAQUINA BAY, OR

    Science.gov (United States)

    Burrowing, or thalassinid, shrimp structure large areas of intertidal habitat of Pacific Northwest estuaries. This field study utilized a combination of anoxic incubations, porewater dialysis peepers, and benthic chambers to quantify the role of burrowing shrimp species on OM dec...

  8. ENHANCED ORGANIC MATTER REMINERALIZATION AND NUTRIENT TURNOVER BY BURROWING SHRIMP POPULATIONS IN YAQUINA BAY, OR

    Science.gov (United States)

    Burrowing thalassinid shrimp are major ecological components of Pacific Northwest (PNW) estuaries and where they structure large areas of intertidal and shallow subtidal habitat. These crustaceans occur in dense beds (>250 m-2) and dig extensive burrow systems (>1 m) controlling ...

  9. Low Bone Turnover and Low BMD in Down Syndrome: Effect of Intermittent PTH Treatment

    Science.gov (United States)

    Akel, Nisreen S.; Vander Schilden, Jaclyn; Bacon, Anthony W.; Bracey, John W.; Sowder, Timothy; Skinner, Robert A.; Swain, Frances L.; Hogue, William R.; Leblanc, Donna B.; Gaddy, Dana; Wenger, Galen R.; Suva, Larry J.

    2012-01-01

    Trisomy 21 affects virtually every organ system and results in the complex clinical presentation of Down syndrome (DS). Patterns of differences are now being recognized as patients’ age and these patterns bring about new opportunities for disease prevention and treatment. Low bone mineral density (BMD) has been reported in many studies of males and females with DS yet the specific effects of trisomy 21 on the skeleton remain poorly defined. Therefore we determined the bone phenotype and measured bone turnover markers in the murine DS model Ts65Dn. Male Ts65Dn DS mice are infertile and display a profound low bone mass phenotype that deteriorates with age. The low bone mass was correlated with significantly decreased osteoblast and osteoclast development, decreased bone biochemical markers, a diminished bone formation rate and reduced mechanical strength. The low bone mass observed in 3 month old Ts65Dn mice was significantly increased after 4 weeks of intermittent PTH treatment. These studies provide novel insight into the cause of the profound bone fragility in DS and identify PTH as a potential anabolic agent in the adult low bone mass DS population. PMID:22916188

  10. Substantial Physician Turnover And Beneficiary 'Churn' In A Large Medicare Pioneer ACO.

    Science.gov (United States)

    Hsu, John; Vogeli, Christine; Price, Mary; Brand, Richard; Chernew, Michael E; Mohta, Namita; Chaguturu, Sreekanth K; Weil, Eric; Ferris, Timothy G

    2017-04-01

    Alternative payment models, such as accountable care organizations (ACOs), attempt to stimulate improvements in care delivery by better alignment of payer and provider incentives. However, limited attention has been paid to the physicians who actually deliver the care. In a large Medicare Pioneer ACO, we found that the number of beneficiaries per physician was low (median of seventy beneficiaries per physician, or less than 5 percent of a typical panel). We also found substantial physician turnover: More than half of physicians either joined (41 percent) or left (18 percent) the ACO during the 2012-14 contract period studied. When physicians left the ACO, most of their attributed beneficiaries also left the ACO. Conversely, about half of the growth in the beneficiary population was because of new physicians affiliating with the ACO; the remainder joined after switching physicians. These findings may help explain the muted financial impact ACOs have had overall, and they raise the possibility of future gaming on the part of ACOs to artificially control spending. Policy refinements include coordinated and standardized risk-sharing parameters across payers to prevent any dilution of the payment incentives or confusion from a cacophony of incentives across payers. Project HOPE—The People-to-People Health Foundation, Inc.

  11. Estimating rates of local species extinction, colonization and turnover in animal communities

    Science.gov (United States)

    Nichols, James D.; Boulinier, T.; Hines, J.E.; Pollock, K.H.; Sauer, J.R.

    1998-01-01

    Species richness has been identified as a useful state variable for conservation and management purposes. Changes in richness over time provide a basis for predicting and evaluating community responses to management, to natural disturbance, and to changes in factors such as community composition (e.g., the removal of a keystone species). Probabilistic capture-recapture models have been used recently to estimate species richness from species count and presence-absence data. These models do not require the common assumption that all species are detected in sampling efforts. We extend this approach to the development of estimators useful for studying the vital rates responsible for changes in animal communities over time; rates of local species extinction, turnover, and colonization. Our approach to estimation is based on capture-recapture models for closed animal populations that permit heterogeneity in detection probabilities among the different species in the sampled community. We have developed a computer program, COMDYN, to compute many of these estimators and associated bootstrap variances. Analyses using data from the North American Breeding Bird Survey (BBS) suggested that the estimators performed reasonably well. We recommend estimators based on probabilistic modeling for future work on community responses to management efforts as well as on basic questions about community dynamics.

  12. Developmental evolution facilitates rapid adaptation.

    Science.gov (United States)

    Lin, Hui; Kazlauskas, Romas J; Travisano, Michael

    2017-11-21

    Developmental evolution has frequently been identified as a mode for rapid adaptation, but direct observations of the selective benefits and associated mechanisms of developmental evolution are necessarily challenging to obtain. Here we show rapid evolution of greatly increased rates of dispersal by developmental changes when populations experience stringent selection. Replicate populations of the filamentous fungus Trichoderma citrinoviride underwent 85 serial transfers, under conditions initially favoring growth but not dispersal. T. citrinoviride populations shifted away from multicellular growth toward increased dispersal by producing one thousand times more single-celled asexual conidial spores, three times sooner than the ancestral genotype. Conidia of selected lines also germinated fifty percent faster. Gene expression changed substantially between the ancestral and selected fungi, especially for spore production and growth, demonstrating rapid evolution of tight regulatory control for down-regulation of growth and up-regulation of conidia production between 18 and 24 hours of growth. These changes involved both developmentally fixed and plastic changes in gene expression, showing that complex developmental changes can serve as a mechanism for rapid adaptation.

  13. Norepinephrine turnover in heart and spleen of 7-, 22-, and 34 C-acclimated hamsters

    Science.gov (United States)

    Jones, S. B.; Musacchia, X. J.

    1976-01-01

    The relationship of norepinephrine (NE) concentration and endogenous turnover rates in both myocardial and spleen tissues in the golden hamster is examined as a function of chronic exposure to either high or low ambient temperatures. Changes in myocardial and spleen NE turnover values are discussed in terms of functional alterations in sympathetic nerve activity and the importance of such changes in temperature acclimation. It is found that acclimation of hamsters to 7 C for 7-10 weeks results in decreased myocardial NE concentration and an apparent increase in myocardial NE turnover. In contrast, exposure to 34 C for 6-8 weeks results in increased myocardial NE concentration and an apparent decrease in NE turnover in both myocardial and spleen tissues. The implication of altered NE synthesis is that sympathetic nerve activity is reduced with heat acclimation and is enhanced with cold acclimation.

  14. Soil respiration and rates of soil carbon turnover differ among six common European tree species

    DEFF Research Database (Denmark)

    Vesterdal, Lars; Elberling, Bo; Christiansen, Jesper Riis

    2012-01-01

    The knowledge of tree species effects on soil organic carbon (C) turnover based on rigorous experimental designs is limited for common European deciduous tree species. We assessed soil respiration, and rates of C turnover in six tree species in a more than 30-year-old common garden experiment...... of C turnover were estimated by (i) the ratio of estimated soil heterotrophic respiration (R h) to C stock in forest floor and top mineral soil, (ii) the ratio of litterfall C to forest floor C, (iii) foliar mass loss in litterbags, and (iv) mineral soil C turnover assessed by laboratory incubation....... Soil respiration differed significantly among several species and increased in the order beechSoil respiration was temperature limited with no significant species difference in Q10. Norway spruce soils were significantly driest, and soil respiration was also limited by soil...

  15. A methodology to measure the effectiveness of academic recruitment and turnover

    DEFF Research Database (Denmark)

    Abramo, Giovanni; D’Angelo, Ciriaco Andrea; Rosati, Francesco

    2016-01-01

    of effectiveness used, and between the indicators andthe universities’ overall research performance. In countries that conduct regular nationalassessment exercises, the evaluation of effectiveness in recruitment and turnover couldcomplement the overall research assessments. In particular, monitoring...

  16. ORGANIZATIONAL JUSTICE, COUNTERPRODUCTIVE WORK BEHAVIOR AND TURNOVER INTENTIONS RELATION: MEDIATION BY DEHUMANIZATION AND MODERATION BY GENDER

    National Research Council Canada - National Science Library

    Ishfaq Ahmed; Muhammad Khalid Khan

    2016-01-01

      The core aim of this study is to find the effects of organizational justice on employees' counter productive work behavior and turnover intentions considering the explanatory and moderating roles...

  17. Effects of meclofenoxate on the level and turnover of biogenic monoamines in the rat brain.

    Science.gov (United States)

    Petkov, V V; Grahovska, T; Petkov, V D; Konstantinova, E

    1985-01-01

    The level and turnover of biogenic monoamines in some rat brain structures were determined after treatment with meclofenoxate at a dose of 50 mg/kg administered i.p. two times a day (9 a.m. and 5 p.m.) for 5 days. Meclofenoxate decreased dopamine (DA) turnover in the frontal cortex and striatum and highly increased it in the hypothalamus. The DA level significantly declined in the striatum, tended to decline in the cortex and significantly rose in the hypothalamus. The noradrenaline (NA) turnover and level in the cortex and striatum were decreased. Meclofenoxate decreased serotonin (5-HT) turnover in the cortex, striatum and hypothalamus and increased it in the pons. At the same time, the 5-HT level rose in the cortex, striatum and pons and declined in the hypothalamus. These results suggest the neurochemical basis of the psychotropic and neuroendocrine effects of meclofenoxate.

  18. The Role Of LMX In Employees Job Motivation, Satisfaction, Empowerment, Stress And Turnover: Cross Country Analysis

    National Research Council Canada - National Science Library

    Maria Malik; Difang Wan; Muhammad Ishfaq Ahmad; Muhammad Akram Naseem; Ramiz ur Rehman

    2015-01-01

      We investigated the effect of Leader Member Exchange (LMX) quality relationship on employee motivation, stress, turnover, satisfaction and Psychological Empowerment with a sample of 1500 employees across four countries...

  19. Dynamics of psychological contracts with work engagement and turnover intention: the influence of organizational tenure

    NARCIS (Netherlands)

    Bal, P.M.; de Cooman, R.; Mol, S.T.

    2013-01-01

    This study investigated the interrelations of the psychological contract with work engagement and turnover intention, which has hitherto been a largely overlooked topic in psychological contract research. Although previous research has mainly focused on how psychological contracts influence job

  20. Using Absenteeism and Performance To Predict Employee Turnover: Early Detection through Company Records.

    Science.gov (United States)

    Morrow, Paula C.; McElroy, James C.; Laczniak, Kathleen S.; Fenton, James B.

    1999-01-01

    Results of a comparison of 113 insurance company employees who left voluntarily with 113 who stayed supported a relationship between absenteeism, performance ratings, and voluntary turnover. There was no significant interaction effect. (SK)

  1. Impact of work environment and work-related stress on turnover intention in physical therapists

    National Research Council Canada - National Science Library

    Lee, Byoung-kwon; Seo, Dong-kwon; Lee, Jang-Tae; Lee, A-Ram; Jeon, Ha-Neul; Han, Dong-Uk

    2016-01-01

    .... It should help create efficient personnel and organization management by exploring the impact of the work environment and work-related stress on turnover intention and analyzing the correlation between them...

  2. Factors affecting employee turnover and sound retention strategies in business organization: a conceptual view

    Directory of Open Access Journals (Sweden)

    Chowdhury Abdullah Al Mamun

    2017-03-01

    Full Text Available “Employee turnover” as an expression is broadly used in business organization. Despite the fact that several studies have been performed on this topic, little research has been conducted on examining the causes and leading factors of turnover as well, as advising some feasible approaches, which can be applied by bosses to ensure that employees will continue in their respective organizations to enhance organizational effectiveness and productivity. The main purpose of this study is to determine the reasons and key factors in the perspectives of the relevant literature and identify to the intention of employee turnover. This conceptual paper also suggests various possible strategies on how to minimize the turnover and retain employees in the organizations. Hence, the paper has proposed a conceptual framework that shows the major variables in explaining the phenomenon of employee turnover and addressing sound retention strategies to handle these issues.

  3. The Effect of Organizational Justice on Accountants’ Job Satisfaction and Turnover Intention

    Directory of Open Access Journals (Sweden)

    Gökhan ÖZER

    2010-12-01

    Full Text Available The purpose of this study is to investigate how the accounting profession members’ who work dependently in accounting firms (vocational trainees, CAs and CPAs perception of organizational justice effect the formation of job satisfaction and turnover intention in order to understand and put forward the phenomenon of turnover among accountants. Organizational justice has been investigated under the sub-dimensions as distributive and procedurel justice. According to the findings attained as a result of the analysis of the data obtained from the survey that was carried out with 240 accountants working in different regions of Turkey and who were chosen randomly for this study; 1 as procedural justice perception increase accountants’ job satisfaction increase as well but their turnover intention decrease 2 as job satisfaction increase accountant’ turnover intention decrease

  4. WORK OVERLOAD AND TURNOVER INTENTION OF JUNIOR AUDITORS IN GREATER JAKARTA, INDONESIA

    Directory of Open Access Journals (Sweden)

    Andika Pradana

    2015-11-01

    Full Text Available This paper aims to analyze how work overload influences turnover intentions of newly hired junior auditors in public accounting offices. Job satisfaction, work related stress and work life conflicts are used as mediating variables between work overload and turnover intention. This study employed 141 auditors from several accounting firms operating in the Greater Jakarta region. The sample was selected using purposive sampling. Three mediation hypotheses were tested using Structural Equation Modeling (SEM. The results show that work overload has a significant effect on increas- ing turnover intention through both job satisfaction and work related stress. In comparison, work overload does not influence turnover intention through work life balance. This may be due to the nature of the respondents, in which a majority of the newly hired accountants employed in this study are unmarried.

  5. The Impact of Staff Turnover on Workplace Demands and Coworker Relationships

    Science.gov (United States)

    Knight, Danica K.; Becan, Jennifer E.; Flynn, Patrick M.

    2016-01-01

    Turnover among clinical staff can have detrimental effects on service provision and organizational efficiency. But how does it affect staff who remain employed at the agency? Researchers at the Institute of Behavioral Research at Texas Christian University sought to answer this question by examining the impact of staff turnover on perceptions of workplace demands and support among 353 clinical staff members from 63 outpatient substance abuse treatment programs. Study results documented that counselors in high-turnover programs reported higher demands (job stress, inadequate staffing) and lower support (communication, collaboration) within their organization, even after controlling for other factors such as decreasing budgets, increasing census, and individual measures of workload. Findings underscore the need to intentionally promote workplace communication and collaboration among staff following the departure of a coworker in order to reduce stress and minimize subsequent turnover among remaining clinical staff. PMID:27540331

  6. Phagocytosis and intracellular digestion of collagen, its role in turnover and remodelling

    NARCIS (Netherlands)

    Everts, V.; van der Zee, E.; Creemers, L.; Beertsen, W.

    1996-01-01

    Collagens of most connective tissues are subject to continuous remodelling and turnover, a phenomenon which occurs under both physiological and pathological conditions. Degradation of these proteins involves participation of a variety of proteolytic enzymes including members of the following

  7. Effects of immobilization and whole-body vibration on rat serum Type I collagen turnover

    Directory of Open Access Journals (Sweden)

    Gürhan Dönmez

    2016-08-01

    Conclusion: Although 1 week of WBV had a positive effect on type I collagen turnover in controls, it is not an efficient method for repairing tissue damage in the early stage following immobilization.

  8. Critical Role for Monocytes/Macrophages in Rapid Progression to AIDS in Pediatric Simian Immunodeficiency Virus-Infected Rhesus Macaques.

    Science.gov (United States)

    Sugimoto, Chie; Merino, Kristen M; Hasegawa, Atsuhiko; Wang, Xiaolei; Alvarez, Xavier A; Wakao, Hiroshi; Mori, Kazuyasu; Kim, Woong-Ki; Veazey, Ronald S; Didier, Elizabeth S; Kuroda, Marcelo J

    2017-09-01

    Infant humans and rhesus macaques infected with the human or simian immunodeficiency virus (HIV or SIV), respectively, express higher viral loads and progress more rapidly to AIDS than infected adults. Activated memory CD4(+) T cells in intestinal tissues are major primary target cells for SIV/HIV infection, and massive depletion of these cells is considered a major cause of immunodeficiency. Monocytes and macrophages are important cells of innate immunity and also are targets of HIV/SIV infection. We reported previously that a high peripheral blood monocyte turnover rate was predictive for the onset of disease progression to AIDS in SIV-infected adult macaques. The purpose of this study was to determine if earlier or higher infection of monocytes/macrophages contributes to the more rapid progression to AIDS in infants. We observed that uninfected infant rhesus macaques exhibited higher physiologic baseline monocyte turnover than adults. Early after SIV infection, the monocyte turnover further increased, and it remained high during progression to AIDS. A high percentage of terminal deoxynucleotidyltransferase dUTP nick end label (TUNEL)-positive macrophages in the lymph nodes (LNs) and intestine corresponded with an increasing number of macrophages derived from circulating monocytes (bromodeoxyuridine positive [BrdU(+)] CD163(+)), suggesting that the increased blood monocyte turnover was required to rapidly replenish destroyed tissue macrophages. Immunofluorescence analysis further demonstrated that macrophages were a significant portion of the virus-producing cells found in LNs, intestinal tissues, and lungs. The higher baseline monocyte turnover in infant macaques and subsequent macrophage damage by SIV infection may help explain the basis of more rapid disease progression to AIDS in infants.IMPORTANCE HIV infection progresses much more rapidly in pediatric cases than in adults; however, the mechanism for this difference is unclear. Using the rhesus macaque model

  9. Population Dynamics of Owned, Free-Roaming Dogs: Implications for Rabies Control

    Science.gov (United States)

    Conan, Anne; Akerele, Oluyemisi; Simpson, Greg; Reininghaus, Bjorn; van Rooyen, Jacques; Knobel, Darryn

    2015-01-01

    Background Rabies is a serious yet neglected public health threat in resource-limited communities in Africa, where the virus is maintained in populations of owned, free-roaming domestic dogs. Rabies elimination can be achieved through the mass vaccination of dogs, but maintaining the critical threshold of vaccination coverage for herd immunity in these populations is hampered by their rapid turnover. Knowledge of the population dynamics of free-roaming dog populations can inform effective planning and implementation of mass dog vaccination campaigns to control rabies. Methodology/Principal Findings We implemented a health and demographic surveillance system in dogs that monitored the entire owned dog population within a defined geographic area in a community in Mpumalanga Province, South Africa. We quantified demographic rates over a 24-month period, from 1st January 2012 through 1st January 2014, and assessed their implications for rabies control by simulating the decline in vaccination coverage over time. During this period, the population declined by 10%. Annual population growth rates were +18.6% in 2012 and -24.5% in 2013. Crude annual birth rates (per 1,000 dog-years of observation) were 451 in 2012 and 313 in 2013. Crude annual death rates were 406 in 2012 and 568 in 2013. Females suffered a significantly higher mortality rate in 2013 than males (mortality rate ratio [MRR] = 1.54, 95% CI = 1.28–1.85). In the age class 0–3 months, the mortality rate of dogs vaccinated against rabies was significantly lower than that of unvaccinated dogs (2012: MRR = 0.11, 95% CI = 0.05–0.21; 2013: MRR = 0.31, 95% CI = 0.11–0.69). The results of the simulation showed that achieving a 70% vaccination coverage during annual campaigns would maintain coverage above the critical threshold for at least 12 months. Conclusions and Significance Our findings provide an evidence base for the World Health Organization’s empirically-derived target of 70% vaccination coverage

  10. Predicting voluntary turnover in employees using demographic characteristics: A South African case study

    Directory of Open Access Journals (Sweden)

    Anton F. Schlechter

    2016-03-01

    Full Text Available Purpose: Employee turnover presents arguably the biggest threat to business sustainability and is a dynamic challenge faced by businesses globally. In South Africa, organisations compete to attract and retain skilled employees in an environment characterised by a burgeoning skills deficit. Turnover risk management is becoming an important strategy to ensure organisational stability and promote the effective retention of employees. The purpose of this research was to contribute to the practice of turnover risk management by proposing an approach and constructing a model to predict employee turnover based on demographic characteristics readily available in a human resource information system.Design: An exploratory research design was employed. Secondary quantitative data were extracted from an existing human resources database and analysed. Data obtained for 2592 employees in a general insurance company based in South Africa and Namibia formed the basis for the analysis. Logistic regression analysis was employed to predict employee turnover using various demographic characteristics available within the database. A likelihood ratio test was used to build a predictive model and the Akaike information criterion and Schwarz criterion were used to test how much value each variable added to the model and if its inclusion was warranted. The model was tested by conducting statistical tests of the significance of the coefficients. Deviance and Pearson goodness-of-fit statistics as well as the R-square test of significance were used. The overall goodness-of-fit of the model was also tested using the Hosmer and Lemeshow goodness-of-fit test.Findings: The current findings provide partial support for a predictive model explaining employee turnover. The model tested 14 demographic variables and the following five variables were found to have statistically significant predictive value: age, years of service, cost centre, performance score and the interaction

  11. A structural equation model of turnover for a longitudinal survey among early career registered nurses.

    Science.gov (United States)

    Brewer, Carol S; Chao, Ying-Yu; Colder, Craig R; Kovner, Christine T; Chacko, Thomas P

    2015-11-01

    Key predictors of early career nurses' turnover are job satisfaction, organizational commitment, job search, intent to stay, and shock (back injuries) based on the literature review and our previous research. Existing research has often omitted one of these key predictors. The purpose of this study in a sample of early career nurses was to compare predictors of turnover to nurses' actual turnover at two time points in their careers. A multi-state longitudinal panel survey of early career nurses was used to compare a turnover model across two time periods. The sample has been surveyed five times. The sample was selected using a two-stage sample of registered nurses nested in 51 metropolitan areas and nine non-metropolitan, rural areas in 34 states and the District of Columbia. The associations between key predictors of turnover were tested using structural equation modeling and data from the earliest and latest panels in our study. We used predictors from the respondents who replied to the Wave-1 survey in 2006 and their turnover status from Wave 2 in 2007 (N=2386). We compared these results to the remaining respondents' predictors from Wave 4 in 2011 and their turnover status in Wave 5 in 2013 (N=1073). We tested and found no effect for missingness from Wave 1-5 and little evidence of attrition bias. Strong support was found for the relationships hypothesized among job satisfaction, organizational commitment, intent to stay, and turnover, with some support for shock and search in the Wave 1-2 sample. However, for Wave 4-5 sample (n=1073), none of the paths through search were significant, nor was the path from shock to turnover. Nurses in the second analysis who had matured longer in their career did not have a significant response to search or shock (back injuries), which may indicate how easily experienced registered nurses find new jobs and/or accommodation to jobs requiring significant physicality. Nurse turnover is a major concern for healthcare organizations

  12. Job Demand and Job Satisfaction in Latent Groups of Turnover Intention Among Licensed Nurses in Taiwan Nursing Homes.

    Science.gov (United States)

    Chen, I-Hui; Brown, Roger; Bowers, Barbara J; Chang, Wen-Yin

    2015-10-01

    Nurses' turnover intention is not dichotomous; it may reflect intent to leave the profession, intent to leave a type of facility, or intent to leave a specific workplace. In a latent class analysis (LCA) of data from 186 licensed nurses (RNs and LPNs) recruited from 25 nursing homes (NHs) in Taiwan, we classified nurses into turnover intention subgroups based on seven questionnaire items and used a multilevel contrast analysis to characterize the subgroups according to demographic and facility factors, job demand, and job satisfaction. A multilevel probit model was used to examine how job demand and job satisfaction influenced subgroup membership. Three turnover subgroups were identified: high turnover intention (12%), middle turnover intention (57%), and low turnover intention (31%). The high turnover intention subgroup comprised the youngest nurses and had the lowest percentage of registered nurses (RNs); nurses in this subgroup had worked the longest at the current NH and had the greatest likelihood of working at a for-profit facility. Nurses in the middle turnover intention subgroup had the lowest likelihood of working at a for-profit facility. Nurses in the low turnover intention subgroup were primarily RNs and had the shortest work experience in the current facility. Nurses in the high and middle turnover intention subgroups reported lower intrinsic job satisfaction than those with low turnover intention. Extrinsic job satisfaction mediated the relationship between job demand and turnover intention subgroup assignment. The results of this LCA can help target interventions to address heterogeneity of turnover intention and ultimately lessen turnover. © 2015 Wiley Periodicals, Inc.

  13. Intention to leave and employee turnover: expanding understanding of key antecedents in the modern workforce

    OpenAIRE

    Voigt, Emily Anne

    2017-01-01

    This research expanded understanding of the key antecedents of intention to leave and employee turnover in a sample of retail banking employees from a large Australian-based financial institution. In three empirical studies, this research provided unique insights into today‘s workforce and deepened understanding of how work related factors influence intention to leave and turnover. The first study compared the relationships between work attitudes and intention to leave for part-time and f...

  14. Recreational football improves bone mineral density and bone turnover marker profile in elderly men

    DEFF Research Database (Denmark)

    Helge, Eva Wulff; Rostgaard Andersen, Thomas; Schmidt, Jakob Friis

    2014-01-01

    This study examined the effect of recreational football and resistance training on bone mineral density (BMD) and bone turnover markers (BTMs) in elderly men. Twenty-six healthy sedentary men (age 68.2 ± 3.2 years) were randomized into three groups: football (F; n = 9) and resistance training (R; n...... training had no effect. The anabolic response may be due to increased bone turnover, especially improved bone formation....

  15. Work–family climate, organizational commitment, and turnover: Multilevel contagion effects of leaders ⋆

    OpenAIRE

    O’Neill, John W.; Harrison, Michelle M.; Cleveland, Jeannette; Almeida, David; Stawski, Robert; Crouter, Anne C.

    2009-01-01

    This paper presents empirical research analyzing the relationship between work–family climate (operationalized in terms of three work–family climate sub-scales), organizational leadership (i.e., senior manager) characteristics, organizational commitment and turnover intent among 526 employees from 37 different hotels across the US. Using multilevel modeling, we found significant associations between work–family climate, and both organizational commitment and turnover intent, both within and b...

  16. Roles of perceived exchange quality and organisational identification in predicting turnover intention

    OpenAIRE

    Kumar, Manish; Singh, Shailendra

    2012-01-01

    This paper explores whether the perceived quality of the leader–member exchange and the general environment of exchange could predict turnover intention. It further examines the role of organisational identification as an explanatory variable mediating between exchange relationships and turnover intention. The authors used three-step hierarchical linear regressions on a data set collected in two time waves. The results supported the mediating role of organisational identification for the lead...

  17. Impact of work environment and work-related stress on turnover intention in physical therapists

    OpenAIRE

    Lee, Byoung-kwon; Seo, Dong-kwon; Lee, Jang-Tae; Lee, A-Ram; Jeon, Ha-Neul; Han, Dong-Uk

    2016-01-01

    [Purpose] This study was conducted to provide basic data for solutions to reduce the turnover rate of physical therapists. It should help create efficient personnel and organization management by exploring the impact of the work environment and work-related stress on turnover intention and analyzing the correlation between them. [Subjects and Methods] A survey was conducted with 236 physical therapists working at medical institutions in the Daejeon and Chungcheong areas. For the analysis on t...

  18. A multistudy examination of organizational stressors, emotional labor, burnout, and turnover in sport organizations.

    Science.gov (United States)

    Larner, R J; Wagstaff, C R D; Thelwell, R C; Corbett, J

    2017-12-01

    While a growing body of research has examined the types of organizational stressors encountered by individuals and their allied responses, little is known about how such individuals manage their emotional responses to these stressors or the consequences of such behaviors. This article presents novel findings from two studies examining the moderating role that emotional labor plays in the relationship between the frequency of organizational stressor experience, burnout, turnover intentions, and actual turnover in sport. In study 1, participants (n=487) completed measures of organizational stressors (OSI-SP), emotional labor (ELS), burnout (ABQ), and turnover intentions. In study 2, a 6-month longitudinal design was used to examine measures of organizational stressors (OSI-SP), emotional labor (ELS), turnover intentions, and actual turnover. Study 1 showed that surface acting moderated the relationship between the frequency of organizational stressors and burnout in sport. Further, surface acting acted as an important mechanism through which burnout mediated the relationship between the frequency of organizational stressors and turnover intentions. Study 2 showed that surface acting moderated the relationship between the organizational stressor frequency and turnover intentions-but not actual turnover-over time. These results highlight the importance of surface acting in understanding how individuals respond to organizational stressors encountered in sport, expanding our understanding of the positive and negative responses component of the meta-model of stress, emotions, and performance. These findings also highlight potentially deleterious emotion-management behaviors that practitioners might consider when aiming to support individuals encountering organizational stressors in sport. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. The Effect of Organizational Justice on Accountants’ Job Satisfaction and Turnover Intention

    OpenAIRE

    Gökhan ÖZER; Mehmet GÜNLÜK

    2010-01-01

    The purpose of this study is to investigate how the accounting profession members’ who work dependently in accounting firms (vocational trainees, CAs and CPAs) perception of organizational justice effect the formation of job satisfaction and turnover intention in order to understand and put forward the phenomenon of turnover among accountants. Organizational justice has been investigated under the sub-dimensions as distributive and procedurel justice. According to the findings attained as a r...

  20. Rest break organization in geriatric care and turnover: a multimethod cross-sectional study.

    Science.gov (United States)

    Wendsche, Johannes; Hacker, Winfried; Wegge, Jürgen; Schrod, Nadine; Roitzsch, Katharina; Tomaschek, Anne; Kliegel, Matthias

    2014-09-01

    Various determinants of nurses' work motivation and turnover behavior have been examined in previous studies. In this research, we extend this work by investigating the impact of care setting (nursing homes vs. home care services) and the important role of rest break organization. We aimed to identify direct and indirect linkages between geriatric care setting, rest break organization, and registered nurses' turnover assessed over a period of one year. We designed a multimethod cross-sectional study. 80 nursing units (n=45 nursing homes, n=35 home care) in 51 German geriatric care services employing 597 registered nurses. We gathered documentary, interview, and observational data about the organization of rest breaks, registered nurses' turnover, and additional organizational characteristics (type of ownership, location, nursing staff, clients, and client-to-staff-ratio). The findings show that the rest break system in geriatric nursing home units is more regularly as well as collectively organized and causes less unauthorized rest breaks than in home care units. Moreover, the feasibility of collective rest breaks was, as predicted, negatively associated with registered nurses' turnover and affected indirectly the relation between care setting and registered nurses' turnover. Care setting, however, had no direct impact on turnover. Furthermore, registered nurses' turnover was higher in for-profit care units than in public or non-profit units. This study reveals significant differences in rest break organization as a function of geriatric care setting and highlights the role of collective rest breaks for nursing staff retention. Our study underlines the integration of organizational context variables and features of rest break organization for the analysis of nursing turnover. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. A new method for calculating the average period of current assets turnover in the analyzed period

    Directory of Open Access Journals (Sweden)

    Kulakova Julija Nikolaevna

    2015-05-01

    Full Text Available The aim of this study is to develop a new method for calculating the average period of current assets turnover during the analyzed period without using of financial results (revenue, cost, etc.. To prove the advantages of the proposed method in comparison with the traditional method of calculating turnover the example of estimating the mean residence time in the analyzed period of working capital in the form of receivables is developed.

  2. Dynamic structure of stock communities: a comparative study between stock returns and turnover rates

    Science.gov (United States)

    Su, Li-Ling; Jiang, Xiong-Fei; Li, Sai-Ping; Zhong, Li-Xin; Ren, Fei

    2017-07-01

    The detection of community structure in stock market is of theoretical and practical significance for the study of financial dynamics and portfolio risk estimation. We here study the community structures in Chinese stock markets from the aspects of both price returns and turnover rates, by using a combination of the PMFG and infomap methods based on a distance matrix. An empirical study using the overall data set shows that for both returns and turnover rates the largest communities are composed of specific industrial or conceptional sectors and the correlation inside a sector is generally larger than the correlation between different sectors. However, the community structure for turnover rates is more complex than that for returns, which indicates that the interactions between stocks revealed by turnover rates may contain more information. This conclusion is further confirmed by the analysis of the changes in the dynamics of community structures over five sub-periods. Sectors like banks, real estate, health care and New Shanghai take turns to comprise a few of the largest communities in different sub-periods, and more interestingly several specific sectors appear in the communities with different rank orders for returns and turnover rates even in the same sub-period. To better understand their differences, a comparison between the evolution of the returns and turnover rates of the stocks from these sectors is conducted. We find that stock prices only had large changes around important events while turnover rates surged after each of these events relevant to specific sectors, which shows strong evidence that the turnover rates are more susceptible to exogenous shocks than returns and its measurement for community detection may contain more useful information about market structure.

  3. Statistical testing of the association between annual turnover and marketing activities in SMEs using χ2

    Science.gov (United States)

    Pater, Liana; Miclea, Şerban; Izvercian, Monica

    2016-06-01

    This paper considers the impact of SMEs' annual turnover upon its marketing activities (in terms of marketing responsibility, strategic planning and budgeting). Empirical results and literature reviews unveil that SMEs managers incline to partake in planned and profitable marketing activities, depending on their turnover's level. Thus, using the collected data form 131 Romanian SMEs managers, we have applied the Chi-Square Test in order to validate or invalidate three research assumptions (hypotheses), created starting from the empirical and literature findings.

  4. A methodology to measure the effectiveness of academic recruitment and turnover

    DEFF Research Database (Denmark)

    Abramo, Giovanni; D’Angelo, Ciriaco Andrea; Rosati, Francesco

    2016-01-01

    We propose a method to measure the effectiveness of the recruitment and turnover of professors, in terms of their research performance. The method presented is applied tothe case of Italian universities over the period 2008–2012. The work then analyses thecorrelation between the indicators...... of effectiveness used, and between the indicators andthe universities’ overall research performance. In countries that conduct regular nationalassessment exercises, the evaluation of effectiveness in recruitment and turnover couldcomplement the overall research assessments. In particular, monitoring...

  5. Exploring factors influencing voluntary turnover intent of Generation X public servants: A South African case

    OpenAIRE

    Hester Nienaber; Vhusthilo Masibigiri

    2012-01-01

    Purpose: The purpose of this article is to report on the factors perceived to influence the turnover intent of Generation X public servants. The problem: The researcher investigated the factors that Generation X public servants in South Africa perceive as influencing their turnover intent. Design: The problem was studied by way of a case study. The data were collected by means of semi-structured interviews. A total of eight purposively selected Generation X public servants participated ...

  6. Modelling carbon and nitrogen turnover in variably saturated soils

    Science.gov (United States)

    Batlle-Aguilar, J.; Brovelli, A.; Porporato, A.; Barry, D. A.

    2009-04-01

    Natural ecosystems provide services such as ameliorating the impacts of deleterious human activities on both surface and groundwater. For example, several studies have shown that a healthy riparian ecosystem can reduce the nutrient loading of agricultural wastewater, thus protecting the receiving surface water body. As a result, in order to develop better protection strategies and/or restore natural conditions, there is a growing interest in understanding ecosystem functioning, including feedbacks and nonlinearities. Biogeochemical transformations in soils are heavily influenced by microbial decomposition of soil organic matter. Carbon and nutrient cycles are in turn strongly sensitive to environmental conditions, and primarily to soil moisture and temperature. These two physical variables affect the reaction rates of almost all soil biogeochemical transformations, including microbial and fungal activity, nutrient uptake and release from plants, etc. Soil water saturation and temperature are not constants, but vary both in space and time, thus further complicating the picture. In order to interpret field experiments and elucidate the different mechanisms taking place, numerical tools are beneficial. In this work we developed a 3D numerical reactive-transport model as an aid in the investigation the complex physical, chemical and biological interactions occurring in soils. The new code couples the USGS models (MODFLOW 2000-VSF, MT3DMS and PHREEQC) using an operator-splitting algorithm, and is a further development an existing reactive/density-dependent flow model PHWAT. The model was tested using simplified test cases. Following verification, a process-based biogeochemical reaction network describing the turnover of carbon and nitrogen in soils was implemented. Using this tool, we investigated the coupled effect of moisture content and temperature fluctuations on nitrogen and organic matter cycling in the riparian zone, in order to help understand the relative

  7. Health promotion funding, workforce recruitment and turnover in New Zealand.

    Science.gov (United States)

    Lovell, Sarah A; Egan, Richard; Robertson, Lindsay; Hicks, Karen

    2015-06-01

    Almost a decade on from the New Zealand Primary Health Care Strategy and amidst concerns about funding of health promotion, we undertook a nationwide survey of health promotion providers. To identify trends in recruitment and turnover in New Zealand's health promotion workforce. Surveys were sent to 160 organisations identified as having a health focus and employing one or more health promoter. Respondents, primarily health promotion managers, were asked to report budget, retention and hiring data for 1 July 2009 through 1 July 2010. Responses were received from 53% of organisations. Among respondents, government funding for health promotion declined by 6.3% in the year ended July 2010 and health promoter positions decreased by 7.5% (equalling 36.6 full-time equivalent positions). Among staff who left their roles, 79% also left the field of health promotion. Forty-two organisations (52%) reported employing health promoters on time-limited contracts of three years or less; this employment arrangement was particularly common in public health units (80%) and primary health organisations (57%). Among new hires, 46% (n=55) were identified as Maori. Low retention of health promoters may reflect the common use of limited-term employment contracts, which allow employers to alter staffing levels as funding changes. More than half the surveyed primary health organisations reported using fixed-term employment contracts. This may compromise health promotion understanding, culture and institutional memory in these organisations. New Zealand's commitment to addressing ethnic inequalities in health outcomes was evident in the high proportion of Maori who made up new hires.

  8. Mechanism of ATP turnover inhibition in the EJC

    Science.gov (United States)

    Nielsen, Klaus H.; Chamieh, Hala; Andersen, Christian B.F.; Fredslund, Folmer; Hamborg, Kristiane; Le Hir, Hervé; Andersen, Gregers R.

    2009-01-01

    The exon junction complex (EJC) is deposited onto spliced mRNAs and is involved in many aspects of mRNA function. We have recently reconstituted and solved the crystal structure of the EJC core made of MAGOH, Y14, the most conserved portion of MLN51, and the DEAD-box ATPase eIF4AIII bound to RNA in the presence of an ATP analog. The heterodimer MAGOH/Y14 inhibits ATP turnover by eIF4AIII, thereby trapping the EJC core onto RNA, but the exact mechanism behind this remains unclear. Here, we present the crystal structure of the EJC core bound to ADP-AIF3, the first structure of a DEAD-box helicase in the transition-mimicking state during ATP hydrolysis. It reveals a dissociative transition state geometry and suggests that the locking of the EJC onto the RNA by MAGOH/Y14 is not caused by preventing ATP hydrolysis. We further show that ATP can be hydrolyzed inside the EJC, demonstrating that MAGOH/Y14 acts by locking the conformation of the EJC, so that the release of inorganic phosphate, ADP, and RNA is prevented. Unifying features of ATP hydrolysis are revealed by comparison of our structure with the EJC–ADPNP structure and other helicases. The reconstitution of a transition state mimicking complex is not limited to the EJC and eIF4AIII as we were also able to reconstitute the complex Dbp5–RNA–ADP–AlF3, suggesting that the use of ADP–AlF3 may be a valuable tool for examining DEAD-box ATPases in general. PMID:19033377

  9. Effect of exercise on epinephrine turnover in trained and untrained male subjects

    Energy Technology Data Exchange (ETDEWEB)

    Kjaer, M.; Christensen, N.J.; Sonne, B.; Richter, E.A.; Galbo, H.

    1985-10-01

    The kinetics underlying plasma epinephrine concentrations were studied. Six athletes (T) and six sedentary males (C) were given intravenous infusions of TH-labeled epinephrine, after which arterial blood was drawn. They rested sitting and bicycled continuously to exhaustion (60 min at 125 W, 60 min at 160 W, 40 min at 200 W, and 240 W to the end). Work time was 154 +/- 13 (SE) (T) and 75 +/- 6 (C) min. At rest, epinephrine clearance was identical (28.4 +/- 1.3 (T) vs. 29.2 +/- 1.8 (C) ml . kg-1 . min-1), but plasma concentration (1.42 +/- 0.27 (T) vs. 0.71 +/- 0.16 (C) nmol . l-1) and, accordingly, secretion (2.9 +/- 0.7 vs. 1.5 +/- 0.4 nmol . min-1) were higher (P less than 0.05) in T than C subjects. Epinephrine clearance was closely related to relative work load, decreasing from 15% above the basal level at 30% of maximal O2 uptake (VO2 max) to 22% below at 76% of VO2 max. Epinephrine concentrations increased much more with work intensity than could be accounted for by changes in clearance and were, at exhaustion, higher (P less than 0.05) in T (7.2 +/- 1.6) than in C (2.5 +/- 0.7 nmol . l-1) subjects despite similar glucose, heart rate, and hematocrit values. At a given load, epinephrine clearance rapidly became constant, whereas concentration increased continuously. Forearm extraction of epinephrine invalidated use of blood from a cubital vein or a hand vein arterialized by hot water in turnover measurements. During exercise, changes in epinephrine concentrations reflect changes in secretion rather than in clearance. Training may increase adrenal medullary secretory capacity.

  10. Histidine-Rich Glycoprotein Uptake and Turnover Is Mediated by Mononuclear Phagocytes

    Science.gov (United States)

    Tugues, Sònia; Orlova, Anna; Bhoi, Sujata; Padhan, Narendra; Åkerud, Peter; Honjo, Satoshi; Selvaraju, Ram Kumar; Mazzone, Massimiliano; Tolmachev, Vladimir; Claesson-Welsh, Lena

    2014-01-01

    Histidine-rich glycoprotein (HRG) is implicated in tumor growth and metastasis by regulation of angiogenesis and inflammation. HRG is produced by hepatocytes and carried to tissues via the circulation. We hypothesized that HRG's tissue distribution and turnover may be mediated by inflammatory cells. Biodistribution parameters were analyzed by injection of radiolabeled, bioactive HRG in the circulation of healthy and tumor-bearing mice. 125I-HRG was cleared rapidly from the blood and taken up in tissues of healthy and tumor-bearing mice, followed by degradation, to an increased extent in the tumor-bearing mice. Steady state levels of HRG in the circulation were unaffected by the tumor disease both in murine tumor models and in colorectal cancer (CRC) patients. Importantly, stromal pools of HRG, detected in human CRC microarrays, were associated with inflammatory cells. In agreement, microautoradiography identified 125I-HRG in blood vessels and on CD45-positive leukocytes in mouse tissues. Moreover, radiolabeled HRG bound in a specific, heparan sulfate-independent manner, to differentiated human monocytic U937 cells in vitro. Suppression of monocyte differentiation by systemic treatment of mice with anti-colony stimulating factor-1 neutralizing antibodies led to reduced blood clearance of radiolabeled HRG and to accumulation of endogenous HRG in the blood. Combined, our data show that mononuclear phagocytes have specific binding sites for HRG and that these cells are essential for uptake of HRG from blood and distribution of HRG in tissues. Thereby, we confirm and extend our previous report that inflammatory cells mediate the effect of HRG on tumor growth and metastatic spread. PMID:25243896

  11. An engine for global plant diversity: Highest evolutionary turnover and emigration in the American tropics

    Directory of Open Access Journals (Sweden)

    Alexandre eAntonelli

    2015-04-01

    Full Text Available Understanding the processes that have generated the latitudinal biodiversity gradient and the continental differences in tropical biodiversity remains a major goal of evolutionary biology. Here we estimate the timing and direction of range shifts of extant flowering plants (angiosperms between tropical and non-tropical zones, and into and out of the major tropical regions of the world. We then calculate rates of speciation and extinction taking into account incomplete taxonomic sampling. We use a recently published fossil calibrated phylogeny and apply novel bioinformatic tools to code species into user-defined polygons. We reconstruct biogeographic history using stochastic character mapping to compute relative numbers of range shifts in proportion to the number of available lineages through time. Our results, based on the analysis of c. 22,600 species and c. 20 million geo-referenced occurrence records, show no significant differences between the speciation and extinction of tropical and non-tropical angiosperms. This suggests that at least in plants, the tropical biodiversity gradient primarily derives from other factors than differential rates of diversification. In contrast, the outstanding species richness found today in the American tropics (the Neotropics, as compared to tropical Africa and tropical Asia, is associated with significantly higher speciation and extinction rates. This suggests an exceedingly rapid evolutionary turnover, i.e. Neotropical species being formed and replaced by one another at unparalleled rates. In addition, tropical America stands out from other continents by having ‘pumped out’ more species than it received through most of the last 66 million years. These results imply that the Neotropics have acted as an engine for global plant diversity.

  12. The efficiency of a dedicated staff on operating room turnover time in hand surgery.

    Science.gov (United States)

    Avery, Daniel M; Matullo, Kristofer S

    2014-01-01

    To evaluate the effect of orthopedic and nonorthopedic operating room (OR) staff on the efficiency of turnover time in a hand surgery practice. A total of 621 sequential hand surgery cases were retrospectively reviewed. Turnover times for sequential cases were calculated and analyzed with regard to the characteristics of the OR staff being primarily orthopedic or nonorthopedic. A total of 227 turnover times were analyzed. The average turnover time with all nonorthopedic staff was 31 minutes, for having only an orthopedic surgical technician was 32 minutes, for having only an orthopedic circulator was 25 minutes, and for having both an orthopedic surgical technician and a circulator was 20 minutes. Statistical significance was seen when comparing only an orthopedic surgical technician versus both an orthopedic circulator and a surgical technician and when comparing both nonorthopedic staff versus both an orthopedic circulator and a surgical technician. OR efficiency is being increasingly evaluated for its effect on hospital revenue and OR staff costs. Reducing turnover time is one aspect of a multifaceted solution in increasing efficiency. Our study showed that, for hand surgery, orthopedic-specific staff can reduce turnover time. Economic/Decision Analysis III. Copyright © 2014 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  13. The mediating role of job satisfaction between leader-member exchange and turnover intentions.

    Science.gov (United States)

    Han, Guohong Helen; Jekel, Marc

    2011-01-01

    The aim of the present study was to investigate whether job satisfaction mediates between leader-member exchange and nurse turnover intentions. Limited knowledge is available on the mediating role of job satisfaction between leader-member exchange and turnover intentions in the nursing field. This is a cross-sectional survey study. Data were collected in a US hospital. Higher leader-member exchange was associated with lower turnover intentions (β=-0.41, Pmember exchange was positively related to one's job satisfaction (β=0.50, Pmember exchange and job satisfaction were both controlled for, the link between leader-member exchange and turnover intentions was no longer significant (β=-0.12, P>0.05). Job satisfaction mediates the link between leader-member exchange and turnover intentions. The present study reinforces the significant role of managers. Nurse managers can try to cultivate a good relationship with the nurses. This can enhance nurses' job satisfaction and in turn lower their turnover intentions. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd.

  14. Leadership styles of nursing home administrators and their association with staff turnover.

    Science.gov (United States)

    Donoghue, Christopher; Castle, Nicholas G

    2009-04-01

    The purpose of this study was to examine the associations between nursing home administrator (NHA) leadership style and staff turnover. We analyzed primary data from a survey of 2,900 NHAs conducted in 2005. The Online Survey Certification and Reporting database and the Area Resource File were utilized to extract organizational and local economic characteristics of the facilities. A general linear model (GLM) was used to estimate the effects of NHA leadership style, organizational characteristics, and local economic characteristics on nursing home staff turnover for registered nurses (RNs), licensed practical nurses (LPNs), and nurse's aides (NAs). The complete model estimates indicate that NHAs who are consensus managers (leaders who solicit, and act upon, the most input from their staff) are associated with the lowest turnover levels, 7% for RNs, 3% for LPNs, and 44% for NAs. Shareholder managers (leaders who neither solicit input when making a decision nor provide their staffs with relevant information for making decisions on their own) are associated with the highest turnover levels, 32% for RNs, 56% for LPNs, and 168% for NAs. The findings indicate that NHA leadership style is associated with staff turnover, even when the effects of organizational and local economic conditions are held constant. Because leadership strategies are amenable to change, the findings of this study may be used to develop policies for lowering staff turnover.

  15. Impact of work environment and work-related stress on turnover intention in physical therapists.

    Science.gov (United States)

    Lee, Byoung-Kwon; Seo, Dong-Kwon; Lee, Jang-Tae; Lee, A-Ram; Jeon, Ha-Neul; Han, Dong-Uk

    2016-08-01

    [Purpose] This study was conducted to provide basic data for solutions to reduce the turnover rate of physical therapists. It should help create efficient personnel and organization management by exploring the impact of the work environment and work-related stress on turnover intention and analyzing the correlation between them. [Subjects and Methods] A survey was conducted with 236 physical therapists working at medical institutions in the Daejeon and Chungcheong areas. For the analysis on the collected data, correlational and linear regression analyses were conducted using the SPSS 18.0 program and Cronbach's alpha coefficient. [Results] The results showed a statistically significant positive correlation between turnover intention and work-related stress but a statistically significant negative correlation respectively between turnover intention and work environment. Work-related stress (β=0.415) had a significant positive impact on turnover intention and work environment (β=-0.387) had a significant negative impact on turnover intention. [Conclusion] To increase satisfaction level with the profession as well as the workplace for physical therapists, improvement of the work environment was the most necessary primary improvement.

  16. Job embeddedness factors as a predictor of turnover intention among infection control nurses in Korea.

    Science.gov (United States)

    Choi, Jeong Sil; Kim, Kyung Mi

    2015-11-01

    Job embeddedness indicates the degree to which an employee of an organization intends to remain in his or her position at that organization. This study examined how job embeddedness affects infection control nurses' turnover intention along with general characteristics, job satisfaction, and perceived job alternatives. We collected data from a total of 133 infection control nurses using self-reporting questionnaire methods. All questions were answered on a 5-point Likert scale. The average turnover intention was 3.01 ± 0.72 (100-point conversion, 60.2%), and average job satisfaction was 3.48 ± 0.79 (100-point conversion, 69.6%). The average perceived availability of job alternatives was 3.02 ± 0.78 (100-point conversion, 60.4%), and average job embeddedness was 3.33 ± 0.57 (100-point conversion, 66.6%). Predictors of turnover intention were monthly income, perceived availability of job alternatives, and job embeddedness. Job embeddedness among predictors has high explanatory power as a predictor of infection control nurses' turnover intention. Through this study we identified predictors of turnover intention and found that job embeddedness among predictors has high explanatory power as a predictor of infection control nurses' turnover intention. Strategies to enhance infection control nurses' job embeddedness are needed. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

  17. A Rapid-Response Humoral Vaccine Platform Exploiting Pre-Existing Non-Cognate Populations of Anti-Vaccine or Anti-Viral CD4+ T Helper Cells to Confirm B Cell Activation.

    Science.gov (United States)

    Hills, Thomas; Jakeman, Phillip G; Carlisle, Robert C; Klenerman, Paul; Seymour, Leonard W; Cawood, Ryan

    2016-01-01

    The need for CD4+ T cell responses to arise de novo following vaccination can limit the speed of B cell responses. Populations of pre-existing vaccine-induced or anti-viral CD4+ T cells recognising distinct antigens could be exploited to overcome this limitation. We hypothesise that liposomal vaccine particles encapsulating epitopes that are recognised, after processing and B cell MHCII presentation, by pre-existing CD4+ T cells will exploit this pre-existing T cell help and result in improved antibody responses to distinct target antigens displayed on the particle surface. Liposomal vaccine particles were engineered to display the malaria circumsporozoite (CSP) antigen on their surface, with helper CD4+ epitopes from distinct vaccine or viral antigens contained within the particle core, ensuring the B cell response is raised but focused against CSP. In vivo vaccination studies were then conducted in C57Bl/6 mice as models of either vaccine-induced pre-existing CD4+ T cell immunity (using ovalbumin-OVA) or virus-induced pre-existing CD4+ T cell immunity (murine cytomegalovirus-MCMV). Following the establishment of pre-existing by vaccination (OVA in the adjuvant TiterMax® Gold) or infection with MCMV, mice were administered CSP-coated liposomal vaccines containing the relevant OVA or MCMV core CD4+ T cell epitopes. In mice with pre-existing anti-OVA CD4+ T cell immunity, these vaccine particles elicited rapid, high-titre, isotype-switched CSP-specific antibody responses-consistent with the involvement of anti-OVA T helper cells in confirming activation of anti-CSP B cells. Responses were further improved by entrapping TLR9 agonists, combining humoral vaccination signals 'one', 'two' and 'three' within one particle. Herpes viruses can establish chronic infection and elicit significant, persistent cellular immune responses. We then demonstrate that this principle can be extended to re-purpose pre-existing anti-MCMV immunity to enhance anti-CSP vaccine responses

  18. In situ carbon turnover dynamics and the role of soil microorganisms therein: a climate warming study in an Alpine ecosystem.

    Science.gov (United States)

    Djukic, Ika; Zehetner, Franz; Watzinger, Andrea; Horacek, Micha; Gerzabek, Martin H

    2013-01-01

    Litter decomposition represents one of the largest fluxes in the global terrestrial carbon cycle. The aim of this study was to improve our understanding of the factors governing decomposition in alpine ecosystems and how their responses to changing environmental conditions change over time. Our study area stretches over an elevation gradient of 1000 m on the Hochschwab massif in the Northern Limestone Alps of Austria. We used high-to-low elevation soil translocation to simulate the combined effects of changing climatic conditions, shifting vegetation zones, and altered snow cover regimes. In original and translocated soils, we conducted in situ decomposition experiments with maize litter and studied carbon turnover dynamics as well as temporal response patterns of the pathways of carbon during microbial decomposition over a 2-year incubation period. A simulated mean annual soil warming (through down-slope translocation) of 1.5 and 2.7 °C, respectively, resulted in a significantly accelerated turnover of added maize carbon. Changes in substrate quantity and quality in the course of the decomposition appeared to have less influence on the microbial community composition and its substrate utilization than the prevailing environmental/site conditions, to which the microbial community adapted quickly upon change. In general, microbial community composition and function significantly affected substrate decomposition rates only in the later stage of decomposition when the differentiation in substrate use among the microbial groups became more evident. Our study demonstrated that rising temperatures in alpine ecosystems may accelerate decomposition of litter carbon and also lead to a rapid adaptation of the microbial communities to the new environmental conditions. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  19. TIRF microscopy analysis of human Cof1, Cof2, and ADF effects on actin filament severing and turnover.

    Science.gov (United States)

    Chin, Samantha M; Jansen, Silvia; Goode, Bruce L

    2016-04-24

    Dynamic remodeling and turnover of cellular actin networks requires actin filament severing by actin-depolymerizing factor (ADF)/Cofilin proteins. Mammals express three different ADF/Cofilins (Cof1, Cof2, and ADF), and genetic studies suggest that in vivo they perform both overlapping and unique functions. To gain mechanistic insights into their different roles, we directly compared their G-actin and F-actin binding affinities, and quantified the actin filament severing activities of human Cof1, Cof2, and ADF using in vitro total internal reflection fluorescence microscopy. All three ADF/Cofilins had similar affinities for G-actin and F-actin. However, Cof2 and ADF severed filaments much more efficiently than Cof1 at both lower and higher concentrations and using either muscle or platelet actin. Furthermore, Cof2 and ADF were more effective than Cof1 in promoting "enhanced disassembly" when combined with actin disassembly co-factors Coronin-1B and actin-interacting protein 1 (AIP1), and these differences were observed on both preformed and actively growing filaments. To probe the mechanism underlying these differences, we used multi-wavelength total internal reflection fluorescence microscopy to directly observe Cy3-Cof1 and Cy3-Cof2 interacting with actin filaments in real time during severing. Cof1 and Cof2 each bound to filaments with similar kinetics, yet Cof2 induced severing much more rapidly than Cof1, decreasing the time interval between initial binding on a filament and severing at the same location. These differences in ADF/Cofilin activities and mechanisms may be used in cells to tune filament turnover rates, which can vary widely for different actin structures. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. Exploring factors influencing voluntary turnover intent of Generation X public servants: A South African case

    Directory of Open Access Journals (Sweden)

    Hester Nienaber

    2012-12-01

    Full Text Available Purpose: The purpose of this article is to report on the factors perceived to influence the turnover intent of Generation X public servants. The problem: The researcher investigated the factors that Generation X public servants in South Africa perceive as influencing their turnover intent. Design: The problem was studied by way of a case study. The data were collected by means of semi-structured interviews. A total of eight purposively selected Generation X public servants participated in this study. Findings: The findings of the study show that the factors influencing the turnover intent of the Generation X public servants correspond to some of those proposed in the literature, including the nature of the job, traditional attitudes, and organisational context, both on the macro- and the micro-levels. Furthermore, these factors are also congruent with the drivers of engagement as set out in the literature, specifically content, coping, compensation, community and career. One of the implications of the findings of this study is that although the value of employees to organisations were established as long ago as the Renaissance, organisations still do not capitalise on their most important asset. It is in particular the direct (line manager that plays a crucial role in optimising the value-add of employees. Value: This study is original as it was the first to investigate the turnover intentions of Generation X public servants. Generation X employees are important as they are deemed to be the knowledge repositories of organisations and they are next in line to support the organisation when the Baby Boomers retire. The perceived turnover intentions correspond to some of the components of the generic turnover model proposed by Holtom et al. (2008. The question that arises is whether the turnover intentions of Generation X are any different from other generations. Conclusions: Given their unique characteristics, Generation X is a turnover risk, which