Relative Importance of Human Resource Practices on Affective Commitment and Turnover Intention in South Korea and United States

PubMed Central

Lee, Jaeyoon; Sohn, Young Woo; Kim, Minhee; Kwon, Seungwoo; Park, In-Jo

2018-01-01

The main purpose of this study was to investigate the impact of perceived HR practices on affective commitment and turnover intention. This study explored which HR practices were relatively more important in predicting affective commitment and turnover intention. A total of 302 employees from the United States and 317 from South Korea completed the same questionnaires for assessing the aforementioned relationships. The results illustrated that among perceived HR practices, internal mobility had the most significant association with turnover intention in both the United States and South Korea. While internal mobility was a stronger predictor of affective commitment for the United States sample, training was the most important variable for predicting affective commitment in South Korea. The second purpose of the study was to examine whether individuals’ positive affect influences the relationship between perceived HR practices and affective commitment and turnover intention. In the United States, positive affect moderated the relationship between perceived HR practices and affective commitment and turnover intention such that the relationships were stronger for individuals reporting high positive affect relative to those reporting low positive affect. However, these relationships were not significant in South Korea. We discuss the implications of these results, study limitations, and practical suggestions for future research. PMID:29867647

The employee retention triad in health care: Exploring relationships amongst organisational justice, affective commitment and turnover intention.

PubMed

Perreira, Tyrone A; Berta, Whitney; Herbert, Monique

2018-04-01

To increase understanding of the relationships between organisational justice, affective commitment and turnover intention in health care. Turnover in health care is a serious concern, as it contributes to the global nursing shortage and is associated with declines in quality of care, patient safety and patient outcomes. Turnover also impacts care teams and is associated with decreased staff cohesion and morale. A survey was developed and administered to frontline nurses working in the Province of Ontario, Canada. The data were used to test a hypothetical model developed from a review of the literature. The relationships amongst the three constructs were evaluated using structural equation modelling and mediation analysis. The hypothesised model was generally supported, although we were limited to considerations of interpersonal justice, affective commitment to one's organisation and turnover intention. Interpersonal justice is associated with affective commitment to one's organisation, which is negatively associated with turnover intention. Interpersonal justice was also found to be directly and negatively associated with turnover intention. Affective commitment to one's organisation was also found to mediate the relationship between interpersonal justice and turnover intention. The examination of relationships within the "employee retention triad" in a single, comprehensive model is novel and provides new information regarding relational complexity and insights into what healthcare leaders can do to retain employees. Reducing turnover may help to decrease some of the stressors related to turnover for clinical staff remaining at the organisation such as constant onboarding and orientation of new hires, working with less experienced staff and increased workload due to decreased staffing. © 2018 John Wiley & Sons Ltd.

Lignin as a molecular marker of land management impacts on soil C storage and turnover

NASA Astrophysics Data System (ADS)

Panettieri, Marco; Rumpel, Cornelia; Dignac, Marie-France; Billiou, Daniel; Chabbi, Abad

2017-04-01

Implementation of temporary grassland on cropped lands may be a sustainable option to enhance the carbon storage via the accumulation of soil organic matter (SOM). However, carbon storage is not only a matter of quantity, since higher inputs of labile carbon may stimulate soil microbial and fungal communities and induce the degradation of the formerly stabilized SOM, through the so-called priming effect. Therefore, targeted strategies for carbon storage need to consider the stability of newly added SOM at long term. Recently, soil ecologist emphasized the huge spatial variability of soil structure and properties, and the fact that many ecosystem functions of SOM are only achieved if it decomposes. Thus, more attention must be paid to fluxes of carbon rather than to the quantities accumulated. The present study aims to cope with the listed problems. The aim of the study was to use lignin as a molecular marker of plant C turnover, to assess carbon storage provided by a temporary (ley) grassland system situated at the long term experimental observatory in Lusignan (http://www.soere-acbb.com/). Our conceptual approach included plots under permanent grassland, permanent cropland and bare fallow as controls. A soil fractionation into water stable aggregates has been chosen as a strategy to overcome spatial complexity, and compound specific analyses were focused on lignin phenols within the aggregates. The hypothesis of this work is that lignin turnovers may be influenced by land uses, lignin localisation within soil compartments, the nature of litter input (above vs. belowground biomass), aggregate distribution, and plant cover characteristics (crop vs. grass). To test the hypothesis, cycles of storage and degradation of lignin were studied using compound specific stable isotope probing, taking advantage of in situ labelling provided by the switches from C3 to C4 plants (i.e. grassland to continuous maize) in the experimental area. Lignin monophenols were extracted and purified with the CuO oxidation method, then their molecular isotopic content was analyzed with a gas chromatograph coupled with an isotopic ratio mass spectrometer. Turnover of each monomer was evaluated using the values obtained for maize and grass biomass as a reference. Results showed that for syringyl units, the acid monophenols had a faster turnover than their aldehydic form, whereas differences were less pronounced for vanillyl units. The fast degradation of cinnamyl units impeded a reliable determination of their turnover rates. Ley grassland reduced the turnover rates of lignin monophenols within macroaggregates and microaggregates, main contributors of total soil mass, and for vanillyl units of bulk soil. For finer fractions, similar turnover rates were detected under ley grassland and permanent cropland. A possible explanation is the preferential binding of lignin to silt in a first step, followed by a degradation of monophenols and their transformation into compounds that are not detected by the CuO oxidation method. Thus, turnover of SOM compounds constitutes a complex mosaic of different interactions and factor, such as litter origin, land use. Our molecular isotopic study also evidenced that spatial variability must be taken into account to evaluate carbon storage at long-term.

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

PubMed

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.

The 26S Proteasome Degrades the Soluble but Not the Fibrillar Form of the Yeast Prion Ure2p In Vitro

PubMed Central

Wang, Kai; Redeker, Virginie; Madiona, Karine; Melki, Ronald; Kabani, Mehdi

2015-01-01

Yeast prions are self-perpetuating protein aggregates that cause heritable and transmissible phenotypic traits. Among these, [PSI +] and [URE3] stand out as the most studied yeast prions, and result from the self-assembly of the translation terminator Sup35p and the nitrogen catabolism regulator Ure2p, respectively, into insoluble fibrillar aggregates. Protein quality control systems are well known to govern the formation, propagation and transmission of these prions. However, little is known about the implication of the cellular proteolytic machineries in their turnover. We previously showed that the 26S proteasome degrades both the soluble and fibrillar forms of Sup35p and affects [PSI +] propagation. Here, we show that soluble native Ure2p is degraded by the proteasome in an ubiquitin-independent manner. Proteasomal degradation of Ure2p yields amyloidogenic N-terminal peptides and a C-terminal resistant fragment. In contrast to Sup35p, fibrillar Ure2p resists proteasomal degradation. Thus, structural variability within prions may dictate their ability to be degraded by the cellular proteolytic systems. PMID:26115123

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

USGS Publications Warehouse

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.

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

PubMed

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.

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

PubMed

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.

Elevated CO2 and water addition enhance nitrogen turnover in grassland plants with implications for temporal stability.

PubMed

Dijkstra, Feike A; Carrillo, Yolima; Blumenthal, Dana M; Mueller, Kevin E; LeCain, Dan R; Morgan, Jack A; Zelikova, Tamara J; Williams, David G; Follett, Ronald F; Pendall, Elise

2018-05-01

Temporal variation in soil nitrogen (N) availability affects growth of grassland communities that differ in their use and reuse of N. In a 7-year-long climate change experiment in a semi-arid grassland, the temporal stability of plant biomass production varied with plant N turnover (reliance on externally acquired N relative to internally recycled N). Species with high N turnover were less stable in time compared to species with low N turnover. In contrast, N turnover at the community level was positively associated with asynchrony in biomass production, which in turn increased community temporal stability. Elevated CO 2 and summer irrigation, but not warming, enhanced community N turnover and stability, possibly because treatments promoted greater abundance of species with high N turnover. Our study highlights the importance of plant N turnover for determining the temporal stability of individual species and plant communities affected by climate change. © 2018 John Wiley & Sons Ltd/CNRS.

An Analysis of the Factors Affecting the Career Orientation/Turnover Behavior of Female Naval Officers.

DTIC Science & Technology

1987-12-01

that there are five major, levels of needs in an ascending hierarchy: physiological, safety, social, self - esteem and self actualization. Once a need is...California OI FIlE CMP 0 THESIS AN ANALYSIS OF THE FACTORS AFFECTING THE CAREER ORIENTATION/TURNOVER BEHAVIOR OF FEMALE NAVAL OFFICERS by Richard W. Lowell...PROGRAM PROJECT TASK WORK UNIT ELEMENT NO. NO. No. ACCESSION NO A ,gNcg ecc%rv,.y~ra 1AS AFFECTING THE CAREER ORIENTATION/TURNOVER BEHAVIOR OF FEMALE NAVAL

Complexity Science and the Dynamics of Climate and Communication: Reducing Nursing Home Turnover

PubMed Central

Anderson, Ruth A.; Corazzini, Kirsten N.; McDaniel, Reuben R.

2008-01-01

Purpose Turnover in nursing homes is a widespread problem adversely affecting care quality. Using complexity theory, we tested the effect of administrative climate, communication patterns, and the interaction between the two on turnover, controlling for facility context. Design and Methods Perceptions of administrative climate and communication were collected from 3,449 employees in 164 randomly sampled nursing homes, and they were linked to secondary data on facility characteristics, resource allocation, and turnover. We used hierarchical regression to test the hypotheses. Results Climate and communication both affected turnover, but lower turnover was dependent on the interaction between climate and communication. In nursing homes with reward-based administrative climates, higher levels of communication openness and accuracy explained lower turnover of licensed vocational nurses and certified nurse assistants, relative to nursing homes with an ambiguous climate. Adequate staffing and longer tenure of the nursing director were also important predictors of turnover. Implications Although context is important, managers can also influence turnover by addressing climate and communication patterns and by encouraging stable nursing leadership. PMID:15197292

Reconciling opposing soil processes in row-crop agroecosystems via soil functional zone management

USDA-ARS?s Scientific Manuscript database

Sustaining soil productivity in agroecosystems presents a fundamental ecological challenge: nutrient provisioning depends upon aggregate turnover and microbial decomposition of organic matter (SOM); yet to prevent soil depletion these processes must be balanced by those that restore nutrients and SO...

[New nurse turnover intention and influencing factors].

PubMed

Han, Sang Sook; Sohn, In Soon; Kim, Nam Eun

2009-12-01

The study was done to identify turnover intention in new nurses according to characteristics of the nurses and other factors affecting turnover and to provide data to set up a strategy to reduce the turnover. Data were collected from 1,077 new nurses who had less than 12 months employment experience and worked in one of 188 hospitals. Eight research instruments were used. Data analysis was done using SPSS WIN 15.0 program. Several factors influence new nurse turnover intention. The average score for turnover intention was 2.12. The scores for subscales were self efficacy, 3.76, nursing performance, 3.90, job satisfaction, 2.09, organization commitment, 1.28, stress, 1.32, burnout, 2.82 and nursing organizational culture, 3.29. Turnover intention was related to self efficacy, nursing performance, job satisfaction, organization commitment, stress, burnout, nursing organizational culture, duration of in-class training, duration of on the job training, number of hospital beds, length of employment and duration of employment in current workplace. The predicting factors for turnover intention were burnout, stress, duration of employment in the current workplace, self efficacy and nursing performance. Those factors explained 51.6% of turnover intention. New nurse turnover intention can be reduced by mitigating the factors affecting this intention.

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

PubMed

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

The impact of quality of work life on job embeddedness and affective commitment and their co-effect on turnover intention of nurses.

PubMed

Zhao, XiaoWen; Sun, Tao; Cao, QiuRu; Li, Ce; Duan, XiaoJian; Fan, LiHua; Liu, Yan

2013-03-01

To verify with empirical evidence the hypothesised relation and the effect of quality of work life, job embeddedness and affective commitment on turnover intention of clinical nurses in China. High turnover of the nursing workforce in healthcare organisations is a difficult and recurring problem in China as well as in many other countries in the world. It leads to great waste of resources and increases management cost. Developing and retaining the nursing workforce, which is a major challenge faced by human resources practitioners in hospitals and public health agencies, also becomes a subject of interest for management studies. Most of the literature about voluntary turnover focused on such traditional measures as job satisfaction and job alternatives in the past. The introduction of such new concepts as quality of work life, job embeddedness and affective commitment, which views the issue from a much broader and comprehensive spectrum, made a great breakthrough in the turnover study. In this study, we selected quality of work life, job embeddedness and affective commitment - three of the most important factors in employer-employee relations - and analysed the interaction between each one of them, as well as their co-effect on turnover intention of Chinese nurses. Cross-sectional survey and structural equation modelling were applied in studying the self-report questionnaires distributed to 1000 nurses employed in five large-scale government-owned hospitals in Heilongjiang Province, Northeast China. Our study confirmed the hypothesised positive relation of quality of work life with job embeddedness and affective commitment and the hypothesised negative relation of quality of work life with turnover intention, that is, high quality of work life perceived by the nurses enhances their job embeddedness and affective commitment and thus reduces their intention to leave the job. The effect of quality of work life is positive on job embeddedness and affection commitment and negative on turnover intention. Nurse managers should pay great attention to the nurses' perception of quality of work life, and make great efforts in developing strategies and projects that can strengthen the nurses' embeddedness or connection with the job. © 2012 Blackwell Publishing Ltd.

Effect of biochar application and soil temperature on characteristics of organic matter associated with aggregate-size and density fractions

NASA Astrophysics Data System (ADS)

Kaiser, Michael; Grunwald, Dennis; Marhan, Sven; Poll, Christian; Bamminger, Chris; Ludwig, Bernard

2016-04-01

Potential increases in soil temperature due to climate change might result in intensified soil organic matter (SOM) decomposition and thus higher CO2 emissions. Management options to increase and stabilize SOM include the application of biochar. However, the effects of biochar amendments under elevated soil temperatures on SOM dynamics are largely unknown. The objective of this study was to analyze the effect of biochar application and elevated soil temperature on the amount and composition of OM associated with fractions of different turnover kinetics. Samples were taken from four treatments of the Hohenheim Climate Change Experiment with the factors temperature (ambient or elevated by 2.5 °C in 4 cm depth, six years before sampling) and biochar (control and 30 t / ha Miscanthus pyrolysis biochar, one year before sampling) in two depths (0 - 5 and 5 - 15 cm). Basal respiration and microbial biomass C were analyzed within an incubation experiment. Aggregate size-fractions were separated by wet-sieving and the free light, occluded light (oLF), and heavy fractions were isolated by density fractionation. All fractions were analyzed for organic C and δ13C as well as by infrared spectroscopy. Preliminary data suggest that biochar significantly increased basal respiration and that the microbial biomass C was significantly affected by elevated temperature. No biochar-C was found in the microbial biomass. Biochar and elevated temperature had only minor effects on the organic C associated with aggregate-size classes, although biochar was incorporated into all fractions already after one year of application. Biochar application significantly increased the organic C associated with oLF. In most samples affected by biochar, the proportion of C=O groups was significantly increased. The results suggest that already after one year, biochar-mineral interactions were formed leading to an aggregate occlusion of applied biochar. At least in the short-term, the effect of biochar on the amount and composition of OM associated with different aggregate-size and density fractions seem to be independent from soil temperature.

Do chemical gradients within soil aggregates reflect plant/soil interactions?

NASA Astrophysics Data System (ADS)

Krüger, Jaane; Hallas, Till; Kinsch, Lena; Stahr, Simon; Prietzel, Jörg; Lang, Friederike

2016-04-01

As roots and hyphae often accumulate at the surface of soil aggregates, their formation and turnover might be related to the bioavailability especially of immobile nutrients like phosphorus. Several methods have been developed to obtain specific samples from aggregate surfaces and aggregate cores and thus to investigate differences between aggregate shell and core. However, these methods are often complex and time-consuming; therefore most common methods of soil analysis neglect the distribution of nutrients within aggregates and yield bulk soil concentrations. We developed a new sequential aggregate peeling method to analyze the distribution of different nutrients within soil aggregates (4-20 mm) from four forest sites (Germany) differing in concentrations of easily available mineral P. Aggregates from three soil depths (Ah, BwAh, Bw) were isolated, air-dried, and peeled with a sieving machine performing four sieving levels with increasing sieving intensity. This procedure was repeated in quadruplicate, and fractions of the same sample and sieving level were pooled. Carbon and N concentration, citric acid-extractable PO4 and P, as well as total element concentrations (P, K, Mg, Ca, Al, Fe) were analyzed. Additionally, synchrotron-based P K-edge XANES spectroscopy was applied on selected samples to detect P speciation changes within the aggregates. The results reveal for most samples a significantly higher C and N concentration at the surface compared to the interior of the aggregates. Carbon and N gradients get more pronounced with increasing soil depth and decreasing P status of study sites. This might be explained by lower aggregate turnover rates of subsoil horizons and intense bioturbation on P-rich sites. This assumption is also confirmed by concentrations of citric acid-extractable PO4 and P: gradients within aggregates are getting more pronounced with increasing soil depth and decreasing P status. However, the direction of these gradients is site-specific: On P-rich study sites the results reveal a significant depletion of citric acid-extractable PO4 and P on aggregate surfaces in subsoil horizons, while at the other study sites a slight enrichment at the aggregate surfaces could be observed. Total P concentrations show no distinct gradients within topsoil aggregates, but a slight P enrichment at the surface of subsoil aggregates at the P-rich site. A strong correlation with the total Al concentrations may indicate a P speciation change within aggregates (e.g., due to acidification processes). These results were also confirmed by P K-edge XANES spectra of aggregate core and shell samples of the P-rich site: In the aggregate shells of topsoil as well as subsoil aggregates, organic P forms are most dominant (82 and 80 %, respectively) than in the aggregate interior (54 and 66%, respectively). Moreover, P in the shell seems to be completely associated to Al, whereas some of the P in the aggregate interior is bound to Fe and/or Ca. Overall, our results show that plant/soil interactions impact on small-scale distribution and bioavailability of nutrients by root uptake and root-induced aggregate engineering.

Combined effects of positive and negative affectivity and job satisfaction on job performance and turnover intentions.

PubMed

Bouckenooghe, Dave; Raja, Usman; Butt, Arif Nazir

2013-01-01

Capturing data from employee-supervisor dyads (N = 321) from eight organizations in Pakistan, including human service organizations, an electronics assembly plant, a packaging material manufacturing company, and a small food processing plant, we used moderated regression analysis to examine whether the relationships between trait affect (positive affectivity [PA] and negative affectivity [NA]) and two key work outcome variables (job performance and turnover) are contingent upon the level of job satisfaction. We applied the Trait Activation Theory to explain the moderating effect of job satisfaction on the relationship between affect and performance and between affect and turnover. Overall, the data supported our hypotheses. Positive and negative affectivity influenced performance and the intention to quit, and job satisfaction moderated these relationships. We discuss in detail the results of these findings and their implications for research and practice.

Psoriatic T cells reduce epidermal turnover time and affect cell proliferation contributed from differential gene expression.

PubMed

Li, Junqin; Li, Xinhua; Hou, Ruixia; Liu, Ruifeng; Zhao, Xincheng; Dong, Feng; Wang, Chunfang; Yin, Guohua; Zhang, Kaiming

2015-09-01

Psoriasis is mediated primarily by T cells, which reduce epidermal turnover time and affect keratinocyte proliferation. We aimed to identify differentially expressed genes (DEG) in T cells from normal, five pairs of monozygotic twins concordant or discordant for psoriasis, to determine whether these DEG may account for the influence to epidermal turnover time and keratinocyte proliferation. The impact of T cells on keratinocyte proliferation and epidermal turnover time were investigated separately by immunohistochemistry and cultured with (3) H-TdR. mRNA expression patterns were investigated by RNA sequencing and verified by real-time reverse transcription polymerase chain reaction. After co-culture with psoriatic T cells, the expression of Ki-67, c-Myc and p53 increased, while expression of Bcl-2 and epidermal turnover time decreased. There were 14 DEG which were found to participate in the regulation of cell proliferation or differentiation. Psoriatic T cells exhibited the ability to decrease epidermal turnover time and affect keratinocyte proliferation because of the differential expression of PPIL1, HSPH1, SENP3, NUP54, FABP5, PLEKHG3, SLC9A9 and CHCHD4. © 2015 Japanese Dermatological Association.

Factors affecting turnover intentions among public hospital doctors in a middle-level city in central China.

PubMed

Zhang, Fengfan; Luo, Zhenni; Chen, Ting; Min, Rui; Fang, Pengqian

2017-05-01

Objective The aim of the present study was to explore prominent factors affecting turnover intentions among public hospital doctors in urban areas, particularly in Xiangyang City, Hubei Province, a middle-level city in central China. Methods Questionnaires were used to collect data from 284 public hospital doctors. Pearson's Chi-squared was used to assess whether sociodemographic and other factors were related to the turnover intentions of public hospital doctors. Binary logistic regression was performed to determine the significant factors that influence turnover intentions. Results The analysis revealed that 28.2% of public hospital doctors intended to leave the hospital where they were currently employed. Dissatisfaction with working conditions and hospital management processes, as well as work pressures, were significant factors contributing to the turnover intentions of public hospital doctors. Conclusion Research into turnover intentions indicates that public hospital doctors surveyed in urban China give greater weight to their professional environment and career development rather than salary in their employment decisions. What is known about the topic? Turnover of medical staff is a concern to hospital administrators because it is costly and detrimental to organisational performance and quality of care. Most studies have focused on the effects of individual and organisational factors on nurses' intentions to leave their employment. Income dissatisfaction was one of the determining factors of turnover intentions in previous studies. What does this paper add? The satisfaction of public hospital doctors with regard to income is not a determining factor of turnover intentions. In contrast with findings of previous studies, the doctors in public hospitals in urban China in the present study gave greater weight to their professional environment and career development in their employment decisions. What are the implications for practitioners? The findings suggest that health service managers and policy makers should pay greater attention to the factors affecting public hospital doctors' turnover intentions. This study will be useful for optimising public hospital management and minimising the turnover of doctors in China.

Effects of Aging and Cyclosporin A on Collagen Turnover in Human Gingiva

PubMed Central

Gagliano, N; Costa, F; Tartaglia, G.M; Pettinari, L; Grizzi, F; Sforza, C; Portinaro, N; Gioia, M; Annoni, G

2009-01-01

Background: We aimed at characterizing the aging gingiva analyzing: i) collagen content and turnover in human gingival tissues and fibroblasts obtained from healthy young and aging subjects. ii) the effect of cyclosporin A administration in human cultured gingival fibroblasts obtained from aging compared to young subjects. Methods: Morphological analysis was performed on haematoxylin-eosin and Sirius red stained paraffin-embedded gingival biopsies from young and aging healthy subjects. The expression of the main genes and proteins involved in collagen turnover were determined by real time PCR, dot blot and SDS-zymography on cultured young and aging gingival fibroblasts, and after cyclosporin A administration. Results: Our results suggest that in healthy aged people, gingival connective tissue is characterized by a similar collagen content and turnover. Collagen turnover pathways are similarly affected by cyclosporin A treatment in young and aging gingival fibroblasts. Conclusions: Cyclosporin A administration affects gingival collagen turnover pathways in young and aging fibroblasts at the same extent, suggesting that during aging cyclosporin A administration is not related to relevant collagen turnover modifications. PMID:20148173

Process-oriented modelling to identify main drivers of erosion-induced carbon fluxes

NASA Astrophysics Data System (ADS)

Wilken, Florian; Sommer, Michael; Van Oost, Kristof; Bens, Oliver; Fiener, Peter

2017-05-01

Coupled modelling of soil erosion, carbon redistribution, and turnover has received great attention over the last decades due to large uncertainties regarding erosion-induced carbon fluxes. For a process-oriented representation of event dynamics, coupled soil-carbon erosion models have been developed. However, there are currently few models that represent tillage erosion, preferential water erosion, and transport of different carbon fractions (e.g. mineral bound carbon, carbon encapsulated by soil aggregates). We couple a process-oriented multi-class sediment transport model with a carbon turnover model (MCST-C) to identify relevant redistribution processes for carbon dynamics. The model is applied for two arable catchments (3.7 and 7.8 ha) located in the Tertiary Hills about 40 km north of Munich, Germany. Our findings indicate the following: (i) redistribution by tillage has a large effect on erosion-induced vertical carbon fluxes and has a large carbon sequestration potential; (ii) water erosion has a minor effect on vertical fluxes, but episodic soil organic carbon (SOC) delivery controls the long-term erosion-induced carbon balance; (iii) delivered sediments are highly enriched in SOC compared to the parent soil, and sediment delivery is driven by event size and catchment connectivity; and (iv) soil aggregation enhances SOC deposition due to the transformation of highly mobile carbon-rich fine primary particles into rather immobile soil aggregates.

Patterns of [PSI+] aggregation allow insights into cellular organization of yeast prion aggregates

PubMed Central

Tyedmers, Jens

2012-01-01

The yeast prion phenomenon is very widespread and mounting evidence suggests that it has an impact on cellular regulatory mechanisms related to phenotypic responses to changing environments. Studying the aggregation patterns of prion amyloids during different stages of the prion life cycle is a first key step to understand major principles of how and where cells generate, organize and turn-over prion aggregates. The induction of the [PSI+] state involves the actin cytoskeleton and quality control compartments such as the Insoluble Protein Deposit (IPOD). An initially unstable transitional induction state can be visualized by overexpression of the prion determinant and displays characteristic large ring- and ribbon-shaped aggregates consisting of poorly fragmented bundles of very long prion fibrils. In the mature prion state, the aggregation pattern is characterized by highly fragmented, shorter prion fibrils that form aggregates, which can be visualized through tagging with fluorescent proteins. The number of aggregates formed varies, ranging from a single large aggregate at the IPOD to multiple smaller ones, depending on several parameters discussed. Aggregate units below the resolution of light microscopy that are detectable by fluorescence correlation spectroscopy are in equilibrium with larger aggregates in this stage and can mediate faithful inheritance of the prion state. Loss of the prion state is often characterized by reduced fragmentation of prion fibrils and fewer, larger aggregates. PMID:22449721

Unraveling the Role of Podocyte Turnover in Glomerular Aging and Injury

PubMed Central

Wanner, Nicola; Hartleben, Björn; Herbach, Nadja; Goedel, Markus; Stickel, Natalie; Zeiser, Robert; Walz, Gerd; Moeller, Marcus J.; Grahammer, Florian

2014-01-01

Podocyte loss is a major determinant of progressive CKD. Although recent studies showed that a subset of parietal epithelial cells can serve as podocyte progenitors, the role of podocyte turnover and regeneration in repair, aging, and nephron loss remains unclear. Here, we combined genetic fate mapping with highly efficient podocyte isolation protocols to precisely quantify podocyte turnover and regeneration. We demonstrate that parietal epithelial cells can give rise to fully differentiated visceral epithelial cells indistinguishable from resident podocytes and that limited podocyte renewal occurs in a diphtheria toxin model of acute podocyte ablation. In contrast, the compensatory programs initiated in response to nephron loss evoke glomerular hypertrophy, but not de novo podocyte generation. In addition, no turnover of podocytes could be detected in aging mice under physiologic conditions. In the absence of podocyte replacement, characteristic features of aging mouse kidneys included progressive accumulation of oxidized proteins, deposits of protein aggregates, loss of podocytes, and glomerulosclerosis. In summary, quantitative investigation of podocyte regeneration in vivo provides novel insights into the mechanism and capacity of podocyte turnover and regeneration in mice. Our data reveal that podocyte generation is mainly confined to glomerular development and may occur after acute glomerular injury, but it fails to regenerate podocytes in aging kidneys or in response to nephron loss. PMID:24408871

Commitment Profiles and Employee Turnover

ERIC Educational Resources Information Center

Stanley, Laura; Vandenberghe, Christian; Vandenberg, Robert; Bentein, Kathleen

2013-01-01

We examined how affective (AC), normative (NC), perceived sacrifice (PS), and few alternatives (FA) commitments combine to form profiles and determine turnover intention and turnover. We theorized that three mechanisms account for how profiles operate, i.e., the degree to which membership is internally regulated, the perceived desirability and…

The Role of Pay Satisfaction in Instructor Satisfaction

ERIC Educational Resources Information Center

Wilson, Jackson

2009-01-01

Voluntary employee turnover is a major factor affecting adventure education (AE) organizations (Garret, 2003). Voluntary turnover often is dysfunctional for both employees and organizations (Birmingham, 1989; Podsakoff, LePine, & LePine, 2007). Turnover can result in increased employee and organizational costs (e.g., McKinney, Bartlett, &…

Intention to leave the profession: antecedents and role in nurse turnover.

PubMed

Parry, Julianne

2008-10-01

This paper is a report of a study to examine the relationship between intention to change profession and intention to change employer among newly graduated nurses. Few studies of the worldwide nursing workforce shortage consider the contribution of changing professions to the shortage. Organizational behaviour research has identified that professional commitment and organizational commitment have an important role in organizational turnover and that professional commitment and intention to change professions may have a greater role in organizational turnover than is presently understood. A model of the relationships between affective professional commitment job satisfaction, organizational commitment, intention to change professions and organizational turnover intention was developed through review of the organizational behaviour literature and tested using path analysis. The sample was drawn from all nurses in Queensland, Australia, entering the workforce for the first time in 2005. The model was tested with a final sample size of 131 nurses in the initial period of exposure to the workplace. Affective professional commitment and organizational commitment were statistically significantly related to intention to change professions. Job satisfaction, organizational commitment and intention to change professions were statistically significantly related to intention to change employer. Turnover research in nursing should include intention to change professions as well as intention to change employer. Policies and practices that enhance the development of affective professional commitment prior to exposure to the workplace and support affective professional commitment, job satisfaction and organizational commitment in the workplace are needed to help reduce nurse turnover.

Staff nurse commitment, work relationships, and turnover intentions: a latent profile analysis.

PubMed

Gellatly, Ian R; Cowden, Tracy L; Cummings, Greta G

2014-01-01

The three-component model of organization commitment has typically been studied using a variable-centered rather than a person-centered approach, preventing a more complete understanding of how these forms of commitment are felt and expressed as a whole. Latent profile analysis was used to identify qualitatively distinct categories or profiles of staff nurses' commitment. Then, associations of the profiles with perceived work unit relations and turnover intentions were examined. Three hundred thirty-six registered nurses provided data on affective, normative, and continuance commitment, perceived work unit relations, and turnover intentions. Latent profile analysis of the nurses' commitment scores revealed six distinct profile groups. Work unit relations and turnover intentions were compared in the six profile-defined groups. Staff nurses with profiles characterized by high affective commitment and/or high normative commitment in relation to other components experienced stronger work unit relations and reported lower turnover intentions. Profiles characterized by high continuance commitment relative to other components or by low overall commitment experienced poorer work unit relations, and the turnover risk was higher. High continuance commitment in combination with high affective and normative commitment was experienced differently than high continuance commitment in combination with low affective and normative commitment. Healthcare organizations often foster commitment by using continuance commitment-enhancing strategies (e.g., offer high salaries and attractive benefits) that may inadvertently introduce behavioral risk. This work suggests the importance of changing the context in which continuance commitment occurs by strengthening the other two components.

The effects of sexual harassment on turnover in the military: time-dependent modeling.

PubMed

Sims, Carra S; Drasgow, Fritz; Fitzgerald, Louise F

2005-11-01

Sexual harassment has consistently negative consequences for working women, including changes in job attitudes (e.g., lower satisfaction) and behaviors (e.g., increased work withdrawal). Cross-sectional evidence suggests that harassment influences turnover intentions. However, few studies have used actual turnover; rather, they rely on proxies. With a sample of 11,521 military servicewomen with turnover data spanning approximately 4 years, the authors used the appropriate method for longitudinal turnover data--Cox's regression--to investigate the impact of harassment on actual turnover. Experiences of harassment led to increased turnover, even after controlling for job satisfaction, organizational commitment, and marital status. Among officers, harassment also affected turnover over and above rank. Given turnover's relevance to organizational bottom lines, these findings have important implications not only for individual women but also for organizations. ((c) 2005 APA, all rights reserved).

Complexity Science and the Dynamics of Climate and Communication: Reducing Nursing Home Turnover

ERIC Educational Resources Information Center

Anderson, Ruth A.; Corazzini, Kirsten N.; McDaniel, Reuben R., Jr.

2004-01-01

Purpose: Turnover in nursing homes is a widespread problem adversely affecting care quality. Using complexity theory, we tested the effect of administrative climate, communication patterns, and the interaction between the two on turnover, controlling for facility context. Design and Methods: Perceptions of administrative climate and communication…

Distal Renal Tubules Are Deficient in Aggresome Formation and Autophagy upon Aldosterone Administration

PubMed Central

Cheema, Muhammad Umar; Damkier, Helle Hasager; Nielsen, Jakob; Poulsen, Ebbe Toftgaard; Enghild, Jan J.; Fenton, Robert A.; Praetorius, Jeppe

2014-01-01

Prolonged elevations of plasma aldosterone levels are associated with renal pathogenesis. We hypothesized that renal distress could be imposed by an augmented aldosterone-induced protein turnover challenging cellular protein degradation systems of the renal tubular cells. Cellular accumulation of specific protein aggregates in rat kidneys was assessed after 7 days of aldosterone administration. Aldosterone induced intracellular accumulation of 60 s ribosomal protein L22 in protein aggregates, specifically in the distal convoluted tubules. The mineralocorticoid receptor inhibitor spironolactone abolished aldosterone-induced accumulation of these aggregates. The aldosterone-induced protein aggregates also contained proteasome 20 s subunits. The partial de-ubiquitinase ataxin-3 was not localized to the distal renal tubule protein aggregates, and the aggregates only modestly colocalized with aggresome transfer proteins dynactin p62 and histone deacetylase 6. Intracellular protein aggregation in distal renal tubules did not lead to development of classical juxta-nuclear aggresomes or to autophagosome formation. Finally, aldosterone treatment induced foci in renal cortex of epithelial vimentin expression and a loss of E-cadherin expression, as signs of cellular stress. The cellular changes occurred within high, but physiological aldosterone concentrations. We conclude that aldosterone induces protein accumulation in distal renal tubules; these aggregates are not cleared by autophagy that may lead to early renal tubular damage. PMID:25000288

Below the Surface of Special Education Administrator Turnover

ERIC Educational Resources Information Center

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…

Dynamic Effects of Teacher Turnover on the Quality of Instruction. Working Paper 170

ERIC Educational Resources Information Center

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…

Employee Turnover: Evidence from a Case Study.

ERIC Educational Resources Information Center

Borland, Jeff

1997-01-01

Patterns of employee turnover from a medium-sized law firm in Australia were examined in regard to theories of worker mobility (matching, sectoral shift, and incentive). Results support a role for matching effects, but personnel practices affect the timing of turnover. Matching and incentive-based theories do not explain the high rates of turnover…

Factors Affecting Turnover Intention for New Graduate Nurses in Three Transition Periods for Job and Work Environment Satisfaction.

PubMed

Yu, Mi; Kang, Kyung Ja

2016-03-01

The turnover rate of new graduate nurses in Korea is twice that of all Korean nurses; job/work environment satisfaction is a known risk factor. The authors examined these factors in new graduate nurses at various transition periods. A cross-sectional survey was conducted using stratified sampling from nine regions of Korea, and 443 new graduate nurses were enrolled. Job/work environment satisfaction and turnover intention were measured. Stepwise multiple regression analysis identified the factors affecting turnover intention. The factors differed through the transition periods. At 0 to 6 months, the factors were work schedule, desired hospital, orientation duration, becoming part of a team, professional development, and practical support; at 7 to 12 months, the factors were work schedule and desired hospital; and at 13 to 18 months, the factor was professional development, which accounted for 31%, 22.9%, and 12.6%, respectively, of the reasons for turnover intention. Reducing turnover intention requires consideration of the influential factors at each transition period. Copyright 2016, SLACK Incorporated.

Analysis of Soil Structure Turnover with Garnet Particles and X-Ray Microtomography

PubMed Central

Vogel, Hans-Jörg

2016-01-01

Matter turnover in soil is tightly linked to soil structure which governs the heterogeneous distribution of habitats, reaction sites and pathways in soil. Thereby, the temporal dynamics of soil structure alteration is deemed to be important for essential ecosystem functions of soil but very little is known about it. A major reason for this knowledge gap is the lack of methods to study soil structure turnover directly at microscopic scales. Here we devise a conceptual approach and an image processing workflow to study soil structure turnover by labeling some initial state of soil structure with small garnet particles and tracking their fate with X-ray microtomography. The particles adhere to aggregate boundaries at the beginning of the experiment but gradually change their position relative to the nearest pore as structure formation progresses and pores are destructed or newly formed. A new metric based on the contact distances between particles and pores is proposed that allows for a direct quantification of soil structure turnover rates. The methodology is tested for a case study about soil compaction of a silty loam soil during stepwise increase of bulk density (ρ = {1.1, 1.3, 1.5} g/cm3). We demonstrate that the analysis of mean contact distances provides genuinely new insights about changing diffusion pathways that cannot be inferred neither from conventional pore space attributes (porosity, mean pore size, pore connectivity) nor from deformation analysis with digital image correlation. This structure labeling approach to quantify soil structure turnover provides a direct analogy to stable isotope labeling for the analysis of matter turnover and can be readily combined with each other. PMID:27453995

A multilevel investigation on nursing turnover intention: the cross-level role of leader-member exchange.

PubMed

Portoghese, Igor; Galletta, Maura; Battistelli, Adalgisa; Leiter, Michael P

2015-09-01

To analyse nursing turnover intention from the unit by using multilevel approach, examining at the individual level, the relationships between job characteristics, job satisfaction and turnover intention, and at the group level the role of leader-member exchange. Research on nursing turnover has given little attention to the effects of multilevel factors. Aggregated data of 935 nurses nested within 74 teams of four Italian hospitals were collected in 2009 via a self-administered questionnaire. Hierarchical linear modelling showed that job satisfaction mediated the relationship between job characteristics and intention to leave at the individual level. At the unit level, leader-member exchange was directly linked to intention to leave. Furthermore, cross-level interaction revealed that leader-member exchange moderated the relationship between job characteristics and job satisfaction. This study supported previous research in single-level turnover studies concerning the key role of job satisfaction, providing evidence that job characteristics are important in creating motivating and satisfying jobs. At the unit-level, leader-member exchange offers an approach to understand the role of unit-specific conditions created by leaders on nurses' workplace wellbeing. This study showed that it is important for nursing managers to recognise the relevance of implementing management practices that foster healthy workplaces centred on high-quality nurse-supervisor relationships. © 2014 John Wiley & Sons Ltd.

A Model-Based Analysis of Chemical and Temporal Patterns of Cuticular Hydrocarbons in Male Drosophila melanogaster

PubMed Central

Kent, Clement; Azanchi, Reza; Smith, Ben; Chu, Adrienne; Levine, Joel

2007-01-01

Drosophila Cuticular Hydrocarbons (CH) influence courtship behaviour, mating, aggregation, oviposition, and resistance to desiccation. We measured levels of 24 different CH compounds of individual male D. melanogaster hourly under a variety of environmental (LD/DD) conditions. Using a model-based analysis of CH variation, we developed an improved normalization method for CH data, and show that CH compounds have reproducible cyclic within-day temporal patterns of expression which differ between LD and DD conditions. Multivariate clustering of expression patterns identified 5 clusters of co-expressed compounds with common chemical characteristics. Turnover rate estimates suggest CH production may be a significant metabolic cost. Male cuticular hydrocarbon expression is a dynamic trait influenced by light and time of day; since abundant hydrocarbons affect male sexual behavior, males may present different pheromonal profiles at different times and under different conditions. PMID:17896002

HDAC6–p97/VCP controlled polyubiquitin chain turnover

PubMed Central

Boyault, Cyril; Gilquin, Benoit; Zhang, Yu; Rybin, Vladimir; Garman, Elspeth; Meyer-Klaucke, Wolfram; Matthias, Patrick; Müller, Christoph W; Khochbin, Saadi

2006-01-01

HDAC6 is a unique cytoplasmic deacetylase capable of interacting with ubiquitin. Using a combination of biophysical, biochemical and biological approaches, we have characterized the ubiquitin-binding domain of HDAC6, named ZnF-UBP, and investigated its biological functions. These studies show that the three Zn ion-containing HDAC6 ZnF-UBP domain presents the highest known affinity for ubiquitin monomers and mediates the ability of HDAC6 to negatively control the cellular polyubiquitin chain turnover. We further show that HDAC6-interacting chaperone, p97/VCP, dissociates the HDAC6–ubiquitin complexes and counteracts the ability of HDAC6 to promote the accumulation of polyubiquitinated proteins. We propose that a finely tuned balance of HDAC6 and p97/VCP concentrations determines the fate of ubiquitinated misfolded proteins: p97/VCP would promote protein degradation and ubiquitin turnover, whereas HDAC6 would favour the accumulation of ubiquitinated protein aggregates and inclusion body formation. PMID:16810319

Caregiving in a patient's place of residence: turnover of direct care workers in home care and hospice agencies.

PubMed

Dill, Janette S; Cagle, John

2010-09-01

High turnover and staff shortages among home care and hospice workers may compromise the quality and availability of in-home care. This study explores turnover rates of direct care workers for home care and hospice agencies. OLS (ordinary least square) regression models are run using organizational data from 93 home care agencies and 29 hospice agencies in North Carolina. Home care agencies have higher total turnover rates than hospice agencies, but profit status may be an important covariate. Higher unemployment rates are associated with lower voluntary turnover. Agencies that do not offer health benefits experience higher involuntary turnover. Differences in turnover between hospice and home health agencies suggest that organizational characteristics of hospice care contribute to lower turnover rates. However, the variation in turnover rates is not fully explained by the proposed multivariate models. Future research should explore individual and structural-level variables that affect voluntary and involuntary turnover in these settings.

Do Employees Leave Just Because They Can? Examining the Perceived Employability-Turnover Intentions Relationship.

PubMed

Acikgoz, Yalcin; Sumer, H Canan; Sumer, Nebi

2016-07-03

The relationship between perceived employability and turnover intentions seems much more complicated than what the common sense would suggest. Based on the reviewed literature, it was expected that job satisfaction, affective commitment, and perceived job security would moderate this relationship. Using a sample of working individuals from different occupations and sectors (N = 721), it was found that employees who perceived themselves as highly employable were more likely to have turnover intentions when their affective commitment was low and perceived job security was high; and the relationship was negative for employees with shorter tenures. Understanding the conditions under which perceived employability is associated with turnover intentions may help organizations design human resource policies that allow them to retain an educated and competent workforce.

Interplay of pathogenic forms of human tau with different autophagic pathways.

PubMed

Caballero, Benjamin; Wang, Yipeng; Diaz, Antonio; Tasset, Inmaculada; Juste, Yves Robert; Stiller, Barbara; Mandelkow, Eva-Maria; Mandelkow, Eckhard; Cuervo, Ana Maria

2018-02-01

Loss of neuronal proteostasis, a common feature of the aging brain, is accelerated in neurodegenerative disorders, including different types of tauopathies. Aberrant turnover of tau, a microtubule-stabilizing protein, contributes to its accumulation and subsequent toxicity in tauopathy patients' brains. A direct toxic effect of pathogenic forms of tau on the proteolytic systems that normally contribute to their turnover has been proposed. In this study, we analyzed the contribution of three different types of autophagy, macroautophagy, chaperone-mediated autophagy, and endosomal microautophagy to the degradation of tau protein variants and tau mutations associated with this age-related disease. We have found that the pathogenic P301L mutation inhibits degradation of tau by any of the three autophagic pathways, whereas the risk-associated tau mutation A152T reroutes tau for degradation through a different autophagy pathway. We also found defective autophagic degradation of tau when using mutations that mimic common posttranslational modifications in tau or known to promote its aggregation. Interestingly, although most mutations markedly reduced degradation of tau through autophagy, the step of this process preferentially affected varies depending on the type of tau mutation. Overall, our studies unveil a complex interplay between the multiple modifications of tau and selective forms of autophagy that may determine its physiological degradation and its faulty clearance in the disease context. © 2017 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

How the Cultural Contexts of Urban Teaching Affect Novice Science Educators: Implications for School Leaders

ERIC Educational Resources Information Center

Duncan, Marlina

2014-01-01

While the challenge to retain highly competent teachers affects all schools, the crisis is critical in urban districts, which historically suffer from high teacher turnover (Ingersoll, 2004). This high turnover is especially problematic in the content areas of science (Ingersoll & Perda, 2010). Through ethnographic case studies the first year…

Turnover of intra- and extra-aggregate organic matter at the silt-size scale

Treesearch

I. Virto; C. Moni; C. Swanston; C. Chenu

2010-01-01

Temperate silty soils are especially sensitive to organic matter losses associated to some agricultural management systems. Long-term preservation of organic C in these soils has been demonstrated to occur mainly in the silt- and clay-size fractions, although our knowledge about the mechanisms through which it happens remains unclear. Although organic matter in such...

Teacher Turnover Impact on 1st-8th Grade Student Academic Achievement: A Correlational Study

ERIC Educational Resources Information Center

Reid, Johnnie M.

2010-01-01

The impact of schools and students not meeting academic achievement standards affects the community and the nation's future workforce. This paper examines many of the factors influencing achievement with special attention given to the facts of teacher turnover in the schools. Teacher turnover and the sad state of the academic achievement of…

Three-Component Commitment and Turnover: An Examination of Temporal Aspects

ERIC Educational Resources Information Center

Culpepper, Robert A.

2011-01-01

SEM (N = 182) was employed to examine implied temporal aspects of three-component commitment theory as they relate to turnover. Consistent with expectations, affective commitment predicted subsequent turnover in an immediate and relatively short interval of 4 months, but failed to do in a much longer but outlying interval of 5-12 months. Side bet…

Nurse retention and satisfaction in Ecuador: implications for nursing administration.

PubMed

Palmer, Sheri P

2014-01-01

This study explores the characteristics of professional nursing work environments that may affect nursing turnover and satisfaction within a large Ecuadorian hospital. Nursing turnover is a challenge and may compromise patient care. Work dissatisfaction contributes to high turnover. Improving nurse satisfaction can contribute to better patient outcomes. Eighty-eight nurses participated in a quantitative and qualitative survey focusing on nursing satisfaction, turnover and selected organisation characteristics. Issues that may affect nurse satisfaction and turnover were identified using questions from the Nursing Work Index: pay, insufficient number of nurses, undervaluing of nurses by public and the medical team, limited advancement opportunities, lack of autonomy and inflexibility in schedule. Other themes identified from qualitative data are reported. The top factor of decreased satisfaction was low pay as indicated by the Nursing Work Index. The qualitative results showed that low pay was the factor for nurse turnover. Additional factors related to nursing satisfaction can be addressed to improve nurse retention. Along with increasing nursing pay, strategies to consider in decreasing turnover and increasing satisfaction included: providing opportunities for nursing advancement, promoting the value of nursing, creating clinical protocols and enhancing autonomy. This study adds to knowledge about nursing needs and satisfaction in South America. © 2013 John Wiley & Sons Ltd.

Job satisfaction and turnover intention among Jordanian nurses in psychiatric units.

PubMed

Alsaraireh, Faris; Quinn Griffin, Mary T; Ziehm, Scott R; Fitzpatrick, Joyce J

2014-10-01

Psychiatric nursing has been identified as a stressful occupation, and this stress could affect individuals' health, well-being, and job satisfaction. The stress of nurses might also affect the organization in terms of absenteeism and quality of care. The purpose of this study was to examine the relationship between job satisfaction and turnover intention among Jordanian nurses in the psychiatric units of the Jordanian National Mental Health Center. A descriptive, correlational, cross-sectional design was used. Nurses were asked to complete a demographic data sheet and questionnaires regarding job satisfaction and turnover intention. Of the 179 questionnaires distributed, 154 were completed, with an 86% response rate. The results revealed a statistically-significant negative relationship between job satisfaction and turnover intention. The findings of the study are consistent with previous research regarding the negative relationship between job satisfaction and turnover intention. The findings provide new information about Jordanian nurses who work in government hospital psychiatric services. © 2014 Australian College of Mental Health Nurses Inc.

Transformational leadership moderates the relationship between emotional exhaustion and turnover intention among community mental health providers.

PubMed

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.

Transformational Leadership Moderates the Relationship between Emotional Exhaustion and Turnover Intention among Community Mental Health Providers

PubMed Central

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

Hybrid discrete-continuum modeling for transport, biofilm development and solid restructuring including electrostatic effects

NASA Astrophysics Data System (ADS)

Prechtel, Alexander; Ray, Nadja; Rupp, Andreas

2017-04-01

We want to present an approach for the mathematical, mechanistic modeling and numerical treatment of processes leading to the formation, stability, and turnover of soil micro-aggregates. This aims at deterministic aggregation models including detailed mechanistic pore-scale descriptions to account for the interplay of geochemistry and microbiology, and the link to soil functions as, e.g., the porosity. We therefore consider processes at the pore scale and the mesoscale (laboratory scale). At the pore scale transport by diffusion, advection, and drift emerging from electric forces can be taken into account, in addition to homogeneous and heterogeneous reactions of species. In the context of soil micro-aggregates the growth of biofilms or other glueing substances as EPS (extracellular polymeric substances) is important and affects the structure of the pore space in space and time. This model is upscaled mathematically in the framework of (periodic) homogenization to transfer it to the mesoscale resulting in effective coefficients/parameters there. This micro-macro model thus couples macroscopic equations that describe the transport and fluid flow at the scale of the porous medium (mesoscale) with averaged time- and space-dependent coefficient functions. These functions may be explicitly computed by means of auxiliary cell problems (microscale). Finally, the pore space in which the cell problems are defined is time and space dependent and its geometry inherits information from the transport equation's solutions. The microscale problems rely on versatile combinations of cellular automata and discontiuous Galerkin methods while on the mesoscale mixed finite elements are used. The numerical simulations allow to study the interplay between these processes.

Soil organic carbon dynamics under long-term fertilization in a black soil of China: Evidence from stable C isotopes

PubMed Central

Dou, Xiaolin; He, Ping; Zhu, Ping; Zhou, Wei

2016-01-01

Effects of different fertilizers on organic carbon (C) storage and turnover of soil fractions remains unclear. We combined soil fractionation with isotope analyses to examine soil organic carbon (SOC) dynamics after 25 years of fertilization. Five types of soil samples including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, N; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into four aggregate sizes (>2000 μm, 2000–250 μm, 250–53 μm, and <53 μm), and three density fractions: free light fraction (LF), intra-aggregate particulate organic matter (iPOM), and mineral-associated organic matter (mSOM). Physical fractionation showed the iPOM fraction of aggregates dominated C storage, averaging 76.87% of SOC storage. Overall, application of N and NPK fertilizers cannot significantly increase the SOC storage but enhanced C in mSOM of aggregates, whereas MNPK fertilizer resulted in the greatest amount of SOC storage (about 5221.5 g C m2) because of the enhanced SOC in LF, iPOM and mSOM of each aggregate. The SNPK fertilizer increased SOC storage in >250 μm aggregates but reduced SOC storage in <250 μm aggregates due to SOC changes in LF and iPOM. PMID:26898121

Soil organic carbon dynamics under long-term fertilization in a black soil of China: Evidence from stable C isotopes.

PubMed

Dou, Xiaolin; He, Ping; Zhu, Ping; Zhou, Wei

2016-02-22

Effects of different fertilizers on organic carbon (C) storage and turnover of soil fractions remains unclear. We combined soil fractionation with isotope analyses to examine soil organic carbon (SOC) dynamics after 25 years of fertilization. Five types of soil samples including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, N; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into four aggregate sizes (>2000 μm, 2000-250 μm, 250-53 μm, and <53 μm), and three density fractions: free light fraction (LF), intra-aggregate particulate organic matter (iPOM), and mineral-associated organic matter (mSOM). Physical fractionation showed the iPOM fraction of aggregates dominated C storage, averaging 76.87% of SOC storage. Overall, application of N and NPK fertilizers cannot significantly increase the SOC storage but enhanced C in mSOM of aggregates, whereas MNPK fertilizer resulted in the greatest amount of SOC storage (about 5221.5 g C m(2)) because of the enhanced SOC in LF, iPOM and mSOM of each aggregate. The SNPK fertilizer increased SOC storage in >250 μm aggregates but reduced SOC storage in <250 μm aggregates due to SOC changes in LF and iPOM.

Plant-mediated effects on extracellular enzyme activities in distinct soil aggregate size classes in field

NASA Astrophysics Data System (ADS)

Kumar, Amit; Dorodnikov, Maxim; Splettstößer, Thomas; Kuzyakov, Yakov; Pausch, Johanna

2017-04-01

Soil aggregation and microbial activities within the aggregates are important factors regulating soil carbon (C) turnover. A reliable and sensitive proxy for microbial activity is activity of extracellular enzymes (EEA). In the present study, effects of soil aggregates on EEA were investigated under three maize plant densities (Low, Normal, and High). Bulk soil was fractionated into three aggregate size classes (>2000 µm large macroaggregates; 2000-250 µm small macroaggregates; <250 µm microaggregates) by optimal-moisture sieving. Microbial biomass and EEA (β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), L-leucine aminopeptidase (LAP) and acid phosphatase (acP)) catalyzing soil organic matter (SOM) decomposition were measured in rooted soil of maize and soil from bare fallow. Microbial biomass C (Cmic) decreased with decreasing aggregate size classes. Potential and specific EEA (per unit of Cmic) increased from macro- to microaggregates. In comparison with bare fallow soil, specific EEA of microaggregates in rooted soil was higher by up to 73%, 31%, 26%, and 92% for BG, NAG, acP and LAP, respectively. Moreover, high plant density decreased macroaggregates by 9% compared to bare fallow. Enhanced EEA in three aggregate size classes demonstrated activation of microorganisms by roots. Strong EEA in microaggregates can be explained by microaggregates' localization within the soil. Originally adhering to surfaces of macroaggregates, microaggregates were preferentially exposed to C substrates and nutrients, thereby promoting microbial activity.

The effects of improved metabolic risk factors on bone turnover markers after 12 weeks of simvastatin treatment with or without exercise.

PubMed

Jiang, Jun; Boyle, Leryn J; Mikus, Catherine R; Oberlin, Douglas J; Fletcher, Justin A; Thyfault, John P; Hinton, Pamela S

2014-11-01

Emerging evidence supports an association between metabolic risk factors and bone turnover. Statins and exercise independently improve metabolic risk factors; however whether improvements in metabolic risk factor affects bone turnover is unknown. The purpose of the present study was to: 1) evaluate the relationship between metabolic risk factors and bone turnover; and 2) determine if improvements in metabolic risk factors after 12 weeks of statin treatment, exercise or the combination affect bone turnover. Fifty participants with ≥2 metabolic syndrome defining characteristics were randomly assigned to one of three groups: statin (STAT: simvastatin, 40 mg/day), exercise (EX: brisk walking and/or slow jogging, 45 minutes/day, 5 days/week), or the combination (STAT+EX). Body composition and whole body bone mineral density were measured with dual energy X-ray absorptiometry. Serum markers of bone formation (bone specific alkaline phosphatase, BAP; osteocalcin, OC), resorption (C-terminal peptide of type I collagen, CTX) and metabolic risk factors were determined. Two-factor (time, group) repeated-measures ANCOVA was used to examine changes of metabolic risk factors and bone turnover. General linear models were used to determine the effect of pre-treatment metabolic risk factors on post-treatment bone turnover marker outcomes. Participants with ≥4 metabolic syndrome defining characteristics had lower pre-treatment OC than those with 3 or fewer. OC was negatively correlated with glucose, and CTX was positively correlated with cholesterol. STAT or STAT+EX lowered total and LDL cholesterol. The OC to CTX ratio decreased in all groups with no other significant changes in bone turnover. Higher pre-treatment insulin or body fat predicted a greater CTX reduction and a greater BAP/CTX increase. Metabolic risk factors were negatively associated with bone turnover markers. Short-term statin treatment with or without exercise lowered cholesterol and all treatments had a small effect on bone turnover. Copyright © 2014 Elsevier Inc. All rights reserved.

Effect of staff turnover on staffing: A closer look at registered nurses, licensed vocational nurses, and certified nursing assistants.

PubMed

Kash, Bita A; Castle, Nicholas G; Naufal, George S; Hawes, Catherine

2006-10-01

We examined the effects of facility and market-level characteristics on staffing levels and turnover rates for direct care staff, and we examined the effect of staff turnover on staffing levels. We analyzed cross-sectional data from 1,014 Texas nursing homes. Data were from the 2002 Texas Nursing Facility Medicaid Cost Report and the Area Resource File for 2003. After examining factors associated with staff turnover, we tested the significance and impact of staff turnover on staffing levels for registered nurses (RNs), licensed vocational nurses (LVNs) and certified nursing assistants (CNAs). All three staff types showed strong dependency on resources, such as reimbursement rates and facility payor mix. The ratio of contracted to employed nursing staff as well as RN turnover increased LVN turnover rates. CNA turnover was reduced by higher administrative expenditures and higher CNA wages. Turnover rates significantly reduced staffing levels for RNs and CNAs. LVN staffing levels were not affected by LVN turnover but were influenced by market factors such as availability of LVNs in the county and women in the labor force. Staffing levels are not always associated with staff turnover. We conclude that staff turnover is a predictor of RN and CNA staffing levels but that LVN staffing levels are associated with market factors rather than turnover. Therefore, it is important to focus on management initiatives that help reduce CNA and RN turnover and ultimately result in higher nurse staffing levels in nursing homes.

Methyl group turnover on methyl-accepting chemotaxis proteins during chemotaxis by Bacillus subtilis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thoelke, M.S.; Casper, J.M.; Ordal, G.W.

1990-02-05

The addition of attractant to Bacillus subtilis briefly exposed to radioactive methionine causes an increase of labeling of the methyl-accepting chemotaxis proteins. The addition of attractant to cells radiolabeled for longer times shows no change in the extent of methylation. Therefore, the increase in labeling for the briefly labeled cells is due to an increased turnover of methyl groups caused by attractant. All amino acids gave enhanced turnover. This turnover lasted for a prolonged time, probably spanning the period of smooth swimming caused by the attractant addition. Repellent did not affect the turnover when added alone or simultaneously with attractant.more » Thus, for amino acid attractants, the turnover is probably the excitatory signal, which is seen to extend long into or throughout the adaptation period, not just at the start of it.« less

Unit-level voluntary turnover rates and customer service quality: implications of group cohesiveness, newcomer concentration, and size.

PubMed

Hausknecht, John P; Trevor, Charlie O; Howard, Michael J

2009-07-01

Despite substantial growth in the service industry and emerging work on turnover consequences, little research examines how unit-level turnover rates affect essential customer-related outcomes. The authors propose an operational disruption framework to explain why voluntary turnover impairs customers' service quality perceptions. On the basis of a sample of 75 work units and data from 5,631 employee surveys, 59,602 customer surveys, and organizational records, results indicate that unit-level voluntary turnover rates are negatively related to service quality perceptions. The authors also examine potential boundary conditions related to the disruption framework. Of 3 moderators studied (group cohesiveness, group size, and newcomer concentration), results show that turnover's negative effects on service quality are more pronounced in larger units and in those with a greater concentration of newcomers.

Predictors of actual turnover in a national sample of newly licensed registered nurses employed in hospitals.

PubMed

Brewer, Carol S; Kovner, Christine T; Greene, William; Tukov-Shuser, Magdalene; Djukic, Maja

2012-03-01

This paper is a report of a study of factors that affect turnover of newly licensed registered nurses in United States hospitals. There is a large body of research related to nursing retention; however, there is little information specific to newly licensed registered nurse turnover. Incidence rates of turnover among new nurses are unknown because most turnover data are not from nationally representative samples of nurses. This study used a longitudinal panel design to obtain data from 1653 registered nurses who were recently licensed by examination for the first time. We mailed surveys to a nationally representative sample of hospital registered nurses 1 year apart. The analytic sample consisted of 1653 nurses who responded to both survey mailings in January of 2006 and 2007. Full-time employment and more sprains and strains (including back injuries) result in more turnover. Higher intent to stay and hours of voluntary overtime and more than one job for pay reduces turnover. When we omitted intent to stay from the probit model, less job satisfaction and organizational commitment led to more turnover, confirming their importance to turnover. Magnet Recognition Award(®) hospitals and several other work attributes had no effect on turnover.   Turnover problems are complex, which means that there is no one solution to decreasing turnover. Multiple points of intervention exist. One specific approach that may improve turnover rates is hospital policies that reduce strains and sprains. © 2011 The Authors. Journal of Advanced Nursing © 2011 Blackwell Publishing Ltd.

The Role of Organizational Culture in Retaining Nursing Workforce

PubMed Central

Banaszak-Holl, Jane; Castle, Nicholas G.; Lin, Michael K.; Shrivastwa, Nijika; Spreitzer, Gretchen

2015-01-01

Purpose of the Study: We examined how organizational culture in nursing homes affects staff turnover, because culture is a first step to creating satisfactory work environments. Design and Methods: Nursing home administrators were asked in 2009 to report on facility culture and staff turnover. We received responses from 419 of 1,056 administrators contacted. Respondents reported the strength of cultural values using scales from a Competing Values Framework and percent of staff leaving annually for Registered Nurse (RN), Licensed Practice Nurse (LPN), and nursing aide (NA) staff. We estimated negative binomial models predicting turnover.  Results: Turnover rates are lower than found in past but remain significantly higher among NAs than among RNs or LPNs. Facilities with stronger market values had increased turnover among RNs and LPNs, and among NAs when turnover was adjusted for facilities with few staff. Facilities emphasizing hierarchical internal processes had lower RN turnover. Group and developmental values focusing on staff and innovation only lowered LPN turnover. Finally, effects on NA turnover become insignificant when turnover was adjusted if voluntary turnover was reported. Implications: Organizational culture had differential effects on the turnover of RN, LPN, and NA staff that should be addressed in developing culture-change strategies. More flexible organizational culture values were important for LPN staff only, whereas unexpectedly, greater emphasis on rigid internal rules helped facilities retain RNs. Facilities with a stronger focus on customer needs had higher turnover among all staff. PMID:24218146

Executive turnover: the influence of dispersion and other pay system characteristics.

PubMed

Messersmith, Jake G; Guthrie, James P; Ji, Yong-Yeon; Lee, Jeong-Yeon

2011-05-01

Using tournament theory as a guiding theoretical framework, in this study, we assess the organizational implications of pay dispersion and other pay system characteristics on the likelihood of turnover among individual executives in organizational teams. Specifically, we estimate the effect of these pay system characteristics on executive turnover decisions. We use a multi-industry, multilevel data set composed of executives in publicly held firms to assess the effects of pay dispersion at the individual level. Consistent with previous findings, we find that pay dispersion is associated with an increased likelihood of executive turnover. In addition, we find that other pay characteristics also affect turnover, both directly and through a moderating effect on pay dispersion. Turnover is more likely when executives receive lower portions of overall top management team compensation and when they have more pay at risk. These conditions also moderate the relationship between pay dispersion and individual turnover decisions, as does receiving lower compensation relative to the market.

Turnover, staffing, skill mix, and resident outcomes in a national sample of US nursing homes.

PubMed

Trinkoff, Alison M; Han, Kihye; Storr, Carla L; Lerner, Nancy; Johantgen, Meg; Gartrell, Kyungsook

2013-12-01

The authors examined the relationship of staff turnover to selected nursing home quality outcomes, in the context of staffing and skill mix. Staff turnover is a serious concern in nursing homes as it has been found to adversely affect care. When employee turnover is minimized, better care quality is more likely in nursing homes. Data from the National Nursing Home Survey, a nationally representative sample of US nursing homes, were linked to Nursing Home Compare quality outcomes and analyzed using logistic regression. Nursing homes with high certified nursing assistant turnover had significantly higher odds of pressure ulcers, pain, and urinary tract infections even after controlling for staffing, skill mix, bed size, and ownership. Nurse turnover was associated with twice the odds of pressure ulcers, although this was attenuated when staffing was controlled. This study suggests turnover may be more important in explaining nursing home (NH) outcomes than staffing and skill mix and should therefore be given greater emphasis.

Directional reflectance factors for monitoring spatial changes in soil surface structure and soil organic matter erosion in agricultural systems

NASA Astrophysics Data System (ADS)

Croft, H.; Anderson, K.

2012-04-01

Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of soil organic matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness (SSR), indicating that a soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Accurate, spatially-continuous measurements of SSR are therefore needed at a variety of spatial and temporal scales to understand the spatial nature of SOM erosion and deposition. Remotely-sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Previous work has demonstrated the ability of directional reflectance factors to monitor soil crusting within a controlled laboratory experiment, due to changes in the levels of self-shadowing effects by soil aggregates. However, further research is needed to test this approach in situ, where other soil variables may affect measured reflectance factors and to investigate the use of directional reflectance factors for monitoring soil erosion processes. This experiment assesses the potential of using directional reflectance factors to monitor changes in SSR, aggregate stability and soil organic carbon (SOC) content for two agricultural conditions. Five soil plots representing tilled and seedbed soils were subjected to different durations of natural rainfall, producing a range of different levels of SSR. Directional reflectance factors were measured concomitantly with sampling for soil structural and biochemical tests at each soil plot. Soil samples were taken to measure aggregate stability (wet sieving), SOC (loss on ignition) and soil moisture (gravimetric method). SSM values varied from 8.70 to 20.05% and SOC from 1.33 to 1.05%, across all soil plots. Each plot was characterised using a close-range laser scanning device with a 2 mm sampling interval. The point laser data were geostatistically analysed to provide a spatially-distributed measure of SSR, giving sill variance values from 3.15 to 22.99. Reflectance factors from the soil states were measured using a ground-based hyperspectral spectroradiometer (400-2500 nm) attached to an A-frame device. This method allowed measurement at a range of viewing zenith angles from extreme forwardscatter (-60°) to extreme backscatter (+60°) at a 10° sampling resolution in the solar principal plane. Reflectance measurements were compared to geostatistically-derived indicators of SSR from the laser profile data. Forward-scattered reflectance factors exhibited a very strong relationship to SSR (R2 = 0.84 at -60°; p< 0.05), demonstrating the operational potential of directional reflectance for providing SSR measurements, despite conflicting variation in SSM. SSM also presented an interesting directional signal (R2 = 0.99 at +20°; p< 0.01). Furthermore, the results showed an important link between SRR decline as measured using directional reflectance, with a decline in aggregate stability and SOC content. These findings provide an empirical and theoretical basis for the future retrieval of spatially-continuous assessments of soil surface structure and carbon turnover within a landscape context.

Impact of land use change on soil organic matter dynamics in subalpine grassland

NASA Astrophysics Data System (ADS)

Meyer, Stefanie; Leifeld, Jens; Bahn, Michael; Fuhrer, Jürg

2010-05-01

Information regarding the response of soil organic matter (SOM) in soils to past and expected future land use changes in the European Alps is scarce. Understanding this response requires knowledge of size and residence times of SOM fractions with distinct stabilities. In order to quantify differences between types of land use in the amount, distribution and turnover rates of soil organic carbon (SOC) in subalpine grassland soils, we used soil aggregate and SOM density fractionation in combination with 14C dating. Samples were taken along gradients of different types of land use from meadow (M) to pasture (P) and to abandoned grassland (A) in the Stubai Valley and in the Matsch Valley. Sampling sites in both areas were located at equal altitude (1880 m and 1820 m, respectively) with the same parent material and soil type, but the Matsch Valley receives 400-500 mm less annual rainfall. SOC stocks in the top 10 cm were 2.47 ± 0.32 (M), 2.75 ± 0.32 (P), and 2.50 ± 0.31 kg C/m2 (A) in the Stubai Valley and 2.25 ± 0.14 (M), 3.45 ± 0.22 (P), 3.16 ± 0.27 kg C/m2(A) in the Matsch Valley. Three aggregate size classes were separated by wet sieving: 2 mm. The light floating fraction (wPOM, ρ >1 g/cm3) was included in the analysis. Free (f-) and occluded particulate organic matter (oPOM) were isolated from each aggregate size class (ρ >1.6 g/cm3). At both locations, more than 80% of SOC was stored in small (0.25-2 mm) and large (>2 mm) macroaggregates, but no trend in relation to the different types of land use could be detected. The fraction of C in fPOM and in oPOM in all aggregate size classes was highest for soil from abandoned grasslands. The bulk soil of the abandoned site in the Stubai Valley showed a significantly higher share of fPOM-C and oPOM-C and a higher amount of wPOM-C as compared to the soil from managed grassland, whereas in the Matsch Valley pasture soil had a significantly higher wPOM-C content. At both sites, 13C natural abundance analyses revealed a gradient in 13C between density fractions. wPOM was particularly useful to reveal differences between sampling sites. Radiocarbon values emphasized the importance of this fraction for the calculation of the turnover of bulk soil C. wPOM turned out to be the most active fraction turning over in 2-4 years. Bulk SOC turnover time was approximately 46 years for pasture soil and 78 years for meadow soil. In conclusion, density fractionation produced homogenous fractions allowing detection of differences between different land use types. However, C distribution among aggregates did not systematically differ.

Dopamine D1 receptor density in the mPFC responds to cognitive demands and receptor turnover contributes to general cognitive ability in mice.

PubMed

Wass, Christopher; Sauce, Bruno; Pizzo, Alessandro; Matzel, Louis D

2018-03-14

In both humans and mice, performance on tests of intelligence or general cognitive ability (GCA) is related to dopamine D1 receptor-mediated activity in the prelimbic cortex, and levels of DRD1 mRNA predict the GCA of mice. Here we assessed the turnover rate of D1 receptors as well as the expression level of the D1 chaperone protein (DRiP78) in the medial PPC (mPFC) of mice to determine whether rate of receptor turnover was associated with variations in the GCA of genetically heterogeneous mice. Following assessment of GCA (aggregate performance on four diverse learning tests) mice were administered an irreversible dopamine receptor antagonist (EEDQ), after which the density of new D1 receptors were quantified. GCA was positively correlated with both the rate of D1 receptor recovery and levels of DRiP78. Additionally, the density of D1 receptors was observed to increase within 60 min (or less) in response to intense demands on working memory, suggesting that a pool of immature receptors was available to accommodate high cognitive loads. These results provide evidence that innate general cognitive abilities are related to D1 receptor turnover rates in the prefrontal cortex, and that an intracellular pool of immature D1 receptors are available to accommodate cognitive demands.

Does the increased air humidity affect soil respiration and carbon stocks?

NASA Astrophysics Data System (ADS)

Kukumägi, Mai; Celi, Luisella; Said-Pullicino, Daniel; Kupper, Priit; Sõber, Jaak; Lõhmus, Krista; Kutti, Sander; Ostonen, Ivika

2013-04-01

Climate manipulation experiments at ecosystem-scale enable us to simulate, investigate and predict changes in carbon balance of forest ecosystems. Considering the predicted increase in air humidity and precipitation for northern latitudes, this work aimed at investigating the effect of increased air humidity on soil respiration, distribution of soil organic matter (SOM) among pools having different turnover times, and microbial, fine root and rhizome biomass. The study was carried out in silver birch (Betula pendula Roth.) and hybrid aspen (Populus tremula L. × P. tremuloides Michx.) stands in a Free Air Humidity Manipulation (FAHM) experimental facility containing three humidified (H; on average 7% above current ambient levels since 2008) and three control (C) plots. Soil respiration rates were measured monthly during the growing season using a closed dynamic chamber method. Density fractionation was adopted to separate SOM into two light fractions (free and aggregate-occluded particulate organic matter, fPOM and oPOM respectively), and one heavy fraction (mineral-associated organic matter, MOM). The fine root and rhizome biomass and microbial data are presented for silver birch stands only. In 2011, after 4 growing seasons of humidity manipulation soil organic carbon contents were significantly higher in C plots than H plot (13.5 and 12.5 g C kg-1, respectively), while soil respiration tended to be higher in the latter. Microbial biomass and basal respiration were 13 and 14% higher in H plots than in the C plots, respectively. Twice more fine roots of trees were estimated in H plots, while the total fine root and rhizome biomass (tree + understory) was similar in C and H plots. Fine root turnover was higher for both silver birch and understory roots in H plots. Labile SOM light fractions (fPOM and oPOM) were significantly smaller in H plots with respect to C plots (silver birch and hybrid aspen stands together), whereas no differences were observed in the contents of the more stable MOM. These results strongly suggest that, apart from the predicted increase in temperature and atmospheric carbon and nitrogen concentrations, an increase in free air humidity as a result of climate change may significantly influence the complex belowground carbon cycling by affecting biomass production, soil respiration and organic matter turnover.

Increased Degradation Rates in the Components of the Mitochondrial Oxidative Phosphorylation Chain in the Cerebellum of Old Mice

PubMed Central

Popa-Wagner, Aurel; Sandu, Raluca E.; Cristin, Coman; Uzoni, Adriana; Welle, Kevin A.; Hryhorenko, Jennifer R.; Ghaemmaghami, Sina

2018-01-01

Brain structures differ in the magnitude of age-related neuron loss with the cerebellum being more affected. An underlying cause could be an age-related decline in mitochondrial bioenergetics. Successful aging of mitochondria reflects a balanced turnover of proteins involved in mitochondrial biogenesis and mitophagy. Thus, an imbalance in mitochondrial turnover can contribute to the diminution of cellular function seen during aging. Mitochondrial biogenesis and mitophagy are mediated by a set of proteins including MFN1, MFN2, OPA1, DRP1, FIS1 as well as DMN1l and DNM1, all of which are required for mitochondrial fission. Using N15 labeling, we report that the turnover rates for DMN1l and FIS1 go in opposite directions in the cerebellum of 22-month-old C57BL6j mice as compared to 3-month-old mice. Previous studies have reported decreased turnover rates for the mitochondrial respiratory complexes of aged rodents. In contrast, we found increased turnover rates for mitochondrial proteins of the oxidative phosphorylation chain in the aged mice as compared to young mice. Furthermore, the turnover rate of the components that are most affected by aging –complex III components (ubiquinol cytochrome C oxidoreductase) and complex IV components (cytochrome C oxidase)– was significantly increased in the senescent cerebellum. However, the turnover rates of proteins involved in mitophagy (i.e., the proteasomal and lysosomal degradation of damaged mitochondria) were not significantly altered with age. Overall, our results suggest that an age-related imbalance in the turnover rates of proteins involved in mitochondrial biogenesis and mitophagy (DMN1l, FIS1) in conjunction with an age-related imbalance in the turnover rates of proteins of the complexes III and IV of the electron transfer chain, might impair cerebellar mitochondrial bioenergetics in old mice. PMID:29503614

Superintendent Turnover in Guam

ERIC Educational Resources Information Center

Sanga, Alvin

2017-01-01

Superintendent turnover has been rampant in the public school district in Guam, an unincorporated United States territory; there have been 18 superintendents since the 1981. This qualitative study aimed to identify and analyze potential factors affecting the superintendency in Guam. Social systems theory proposes a number of factors about the…

The role of organizational culture in retaining nursing workforce.

PubMed

Banaszak-Holl, Jane; Castle, Nicholas G; Lin, Michael K; Shrivastwa, Nijika; Spreitzer, Gretchen

2015-06-01

We examined how organizational culture in nursing homes affects staff turnover, because culture is a first step to creating satisfactory work environments. Nursing home administrators were asked in 2009 to report on facility culture and staff turnover. We received responses from 419 of 1,056 administrators contacted. Respondents reported the strength of cultural values using scales from a Competing Values Framework and percent of staff leaving annually for Registered Nurse (RN), Licensed Practice Nurse (LPN), and nursing aide (NA) staff. We estimated negative binomial models predicting turnover.  Turnover rates are lower than found in past but remain significantly higher among NAs than among RNs or LPNs. Facilities with stronger market values had increased turnover among RNs and LPNs, and among NAs when turnover was adjusted for facilities with few staff. Facilities emphasizing hierarchical internal processes had lower RN turnover. Group and developmental values focusing on staff and innovation only lowered LPN turnover. Finally, effects on NA turnover become insignificant when turnover was adjusted if voluntary turnover was reported. Organizational culture had differential effects on the turnover of RN, LPN, and NA staff that should be addressed in developing culture-change strategies. More flexible organizational culture values were important for LPN staff only, whereas unexpectedly, greater emphasis on rigid internal rules helped facilities retain RNs. Facilities with a stronger focus on customer needs had higher turnover among all staff. © The Author 2013. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Aggregation, impaired degradation and immunization targeting of amyloid-beta dimers in Alzheimer’s disease: a stochastic modelling approach

PubMed Central

2012-01-01

Background Alzheimer’s disease (AD) is the most frequently diagnosed neurodegenerative disorder affecting humans, with advanced age being the most prominent risk factor for developing AD. Despite intense research efforts aimed at elucidating the precise molecular underpinnings of AD, a definitive answer is still lacking. In recent years, consensus has grown that dimerisation of the polypeptide amyloid-beta (Aß), particularly Aß42, plays a crucial role in the neuropathology that characterise AD-affected post-mortem brains, including the large-scale accumulation of fibrils, also referred to as senile plaques. This has led to the realistic hope that targeting Aß42 immunotherapeutically could drastically reduce plaque burden in the ageing brain, thus delaying AD onset or symptom progression. Stochastic modelling is a useful tool for increasing understanding of the processes underlying complex systems-affecting disorders such as AD, providing a rapid and inexpensive strategy for testing putative new therapies. In light of the tool’s utility, we developed computer simulation models to examine Aß42 turnover and its aggregation in detail and to test the effect of immunization against Aß dimers. Results Our model demonstrates for the first time that even a slight decrease in the clearance rate of Aß42 monomers is sufficient to increase the chance of dimers forming, which could act as instigators of protofibril and fibril formation, resulting in increased plaque levels. As the process is slow and levels of Aβ are normally low, stochastic effects are important. Our model predicts that reducing the rate of dimerisation leads to a significant reduction in plaque levels and delays onset of plaque formation. The model was used to test the effect of an antibody mediated immunological response. Our results showed that plaque levels were reduced compared to conditions where antibodies are not present. Conclusion Our model supports the current thinking that levels of dimers are important in initiating the aggregation process. Although substantial knowledge exists regarding the process, no therapeutic intervention is on offer that reliably decreases disease burden in AD patients. Computer modelling could serve as one of a number of tools to examine both the validity of reliable biomarkers and aid the discovery of successful intervention strategies. PMID:22748062

Aerobic fitness does not modulate protein metabolism in response to increased exercise: a controlled trial

USDA-ARS?s Scientific Manuscript database

Purpose: This study examined how a sudden increase in exercise energy expenditure affected whole body protein turnover and nitrogen balance in people of differing aerobic fitness. We hypothesized that whole-body protein turnover would be attenuated, and nitrogen balance would be preserved, in aerobi...

Accelerated microbial turnover but constant growth efficiency with warming in soil

Treesearch

Shannon B. Hagerty; Kees Jan van Groenigen; Steven D. Allison; Bruce A. Hungate; Egbert Schwartz; George W. Koch; Randall K. Kolka; Paul Dijkstra

2014-01-01

Rising temperatures are expected to reduce global soil carbon (C) stocks, driving a positive feedback to climate change1-3. However, the mechanisms underlying this prediction are not well understood, including how temperature affects microbial enzyme kinetics, growth effiency (MGE), and turnover4,5. Here, in a laboratory...

Antecedents of Norwegian Beginning Teachers' Turnover Intentions

ERIC Educational Resources Information Center

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'…

Employee Engagement and Turnover Intent: An Analysis of the Thai Public Sector

ERIC Educational Resources Information Center

Tanthasith, Sitthichai

2016-01-01

Organizations these days are facing a number of challenges that affect their performance and productivity. As workplaces become more challenging to employees, employee engagement and turnover become critical concerns for management. Drawing on insights from the Job Demand-Resource model, this study explores the relationships between key…

Organizational Career Growth, Affective Occupational Commitment and Turnover Intentions

ERIC Educational Resources Information Center

Weng, Qingxiong; McElroy, James C.

2012-01-01

Survey data, collected from the People's Republic of China, were used to test Weng's (2010) four facet model of career growth and to examine its effect on occupational commitment and turnover intentions. Weng conceptualized career growth as consisting of four factors: career goal progress, professional ability development, promotion speed, and…

The High Cost of Teacher Turnover. Policy Brief

ERIC Educational Resources Information Center

National Commission on Teaching and America's Future, 2007

2007-01-01

In 2007, the National Commission on Teaching and America's Future (NCTAF) completed an 18-month study of the costs of teacher turnover in five school districts. The selected districts varied in size, location, and demographics enabling exploration of how these variations affected costs. Costs of recruiting, hiring, processing, and training…

Teacher's Turnover Intentions: Examining the Impact of Motivation and Organizational Commitment

ERIC Educational Resources Information Center

Imran, Rabia; Allil, Kamaal; Mahmoud, Ali Bassam

2017-01-01

Purpose: The purpose of this paper is to explore the path of motivation leading to organizational commitment resulting in reduced turnover intentions (TIs). It examines the relationship between dimensions of motivation (amotivation, introjected regulations (IRs) and intrinsic motivation (IM)) with dimensions of commitment (affective, normative and…

Intraorganizational Career Advancement and Voluntary Turnover in a Multinational Bank in Taiwan

ERIC Educational Resources Information Center

Zhao, Wei; Zhou, Xueguang

2008-01-01

Purpose: This study aims to investigate how various aspects of intraorganizational career advancement--current career attainments, recent pace of upward mobility, and future prospect of career advancement--affect voluntary turnover, drawing empirical evidence from a multinational corporation (MNC) in Taiwan's cultural and labor market environment.…

Perinatal exposure to methadone affects central cholinergic activity in the weanling rat.

PubMed

Robinson, S E; Mo, Q; Maher, J R; Wallace, M J; Kunko, P M

1996-06-01

Pregnant rats were implanted with osmotic minipumps containing either methadone hydrochloride (initial dose, 9 mg/kg/day) or sterile water. Their offspring were cross-fostered so that they were exposed to methadone prenatally and/or postnatally. Perinatal methadone exposure disrupted cholinergic activity on postnatal day 21 as measured by the turnover rate of acetylcholine (TRACh) in both female and male rats, although there were some sexually-dimorphic responses. The most profoundly affected brain region was the striatum, where prenatal exposure to methadone increased ACh turnover, whether or not the rats continued to be exposed to methadone postnatally. It appears unlikely that neonatal withdrawal contributes to brain regional changes in ACh turnover, as continued postnatal exposure to methadone did not prevent the prenatal methadone induced changes.

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

PubMed

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.

The role of job satisfaction, work engagement, self-efficacy and agentic capacities on nurses' turnover intention and patient satisfaction.

PubMed

De Simone, Silvia; Planta, Anna; Cicotto, Gianfranco

2018-02-01

Nurses' voluntary turnover is a worrying global phenomenon which affects service quality. Retaining nursing staff within a hospital is important to eliminate the negative influence of voluntary turnover on the quality of care and organisation costs. This research helps explain nurses' voluntary turnover by analysing the role of self-efficacy, agentic capacities, job satisfaction, and work engagement on hospital turnover intention, and to study the relationships between these variables and patient satisfaction. This study gathered data from 194 nurses and 181 patients from 22 inpatient wards at two hospitals in southern Italy. Correlation analysis revealed that job satisfaction, work engagement, self-efficacy and agentic capacities were positively interrelated and negatively correlated with turnover intention. Path analysis showed that self-efficacy, some agentic capacities (anticipation and self-regulation), job satisfaction, and work engagement had direct or indirect effects on nurses' turnover intention, and that job satisfaction exerted a stronger effect on turnover intention. Also, patient satisfaction was positively correlated with nurses' job satisfaction, work engagement, self-efficacy, self-regulation and anticipation and negatively correlated with nurses' turnover intention. Results highlighted the importance of implementing actions (for example through feedforward methodology and the goal setting technique) to improve self-efficacy, self-regulation skill, work engagement and job satisfaction in order to reduce nurses' turnover intention and increase patient satisfaction with nursing care. Copyright © 2017 Elsevier Inc. All rights reserved.

Faculty turnover within academic pharmacy departments.

PubMed

Carter, Orly; Nathisuwan, Surakit; Stoddard, Gregory J; Munger, Mark A

2003-02-01

Pharmacy faculty manpower has been debated within the academic pharmacy community over the last several decades. Previous investigations studied job satisfaction among faculty members, but have not evaluated faculty retention and turnover among academic pharmacy departments. To evaluate retention and turnover rates in the departments of Pharmacy Practice and Basic Science (Pharmacology/Toxicology, Pharmaceutics, Medicinal Chemistry) over the last 5 years. Individual instructors and assistant, associate, and full professors across 80 colleges of pharmacy in the US were tracked between the years 1996 and 2001 using the American Association of Colleges of Pharmacy published rosters. Differences between departments were analyzed by year-stratified cross-tabulation table analysis. A greater percentage of Pharmacy Practice faculty resigned (10.6%) compared with Basic Science faculty (6.0%; percent ratio 1.76; 95% CI 1.58 to 1.95; p < 0.001), which remained constant across each academic year. Approximately 2.7 faculty members left their academic institutions per year in Pharmacy Practice compared with 1.1 faculty members in the aggregate of Basic Science departments. A higher percentage of women resigned in Pharmacy Practice (13.2%) than did men (8.7%; percent ratio 1.5; 95% CI 1.34 to 1.68; p < 0.001), despite a 1.3-fold male to female ratio. Likewise, regardless of a 4.1-fold male to female ratio in the Basic Science group, a higher percentage of women resigned (8.0%) than men (5.5%; percent ratio 1.45; 95% CI 1.18 to 1.78; p < 0.001). Over a 5-year period, Pharmacy Practice exhibited a higher turnover compared with Basic Science. Women displayed significantly higher turnover than men across all pharmacy academic departments. New retention approaches, especially for female faculty members, should be explored.

Workplace stress, job satisfaction, job performance, and turnover intention of health care workers in rural Taiwan.

PubMed

Chao, Ming-Che; Jou, Rong-Chang; Liao, Cing-Chu; Kuo, Chung-Wei

2015-03-01

Workplace stress (WS) has been found to affect job satisfaction (JS), performance, and turnover intentions (TIs) in developed countries, but there is little evidence from other countries and especially rural areas. In rural Taiwan, especially, there is an insufficient health care workforce, and the situation is getting worse. To demonstrate the relationship, we used a cross-sectional structured questionnaire, and data from 344 licensed professionals in 1 rural regional hospital were analyzed using the structural equation model. The results showed that WS had a positive effect on both TI and job performance (JP) but a negative effect on satisfaction. JS did improve performance. For the staff with an external locus of control, stress affected JP and satisfaction significantly. For the staff with lower perceived job characteristics, JS affected performance significantly. The strategies to decrease stress relating to work load, role conflict, family factors, and working environment should be focused and implemented urgently to lower the turnover rate of health care workers in rural Taiwan. © 2013 APJPH.

Population turnover and adaptation in heterogeneous environments

NASA Astrophysics Data System (ADS)

Campos, Paulo R. A.; de Oliveira, Viviane M.

2012-02-01

We study adaptive dynamics in a structured population model of asexual individuals which takes into account environmental heterogeneity among the subpopulations. The key purpose of the present work is to address how population turnovers, i.e. extinction events followed by recolonization, affect the rate of fixation of advantageous mutations. This model is a generalization of our previous model to address the interplay between environmental correlation and evolutionary forces on the adaptive process. The incorporation of population turnovers into the model enables us to make a direct correspondence between the model and host-parasite dynamics (epidemiological models). Strikingly, contrary to the intuitive and usual deleterious effect associated to extinction events, it is observed that population turnovers can in fact speed up adaptation as heterogeneity rises. On the other side, in nearly homogeneous population turnovers have a neutral effect on fixation rates, but a detrimental outcome is also achieved when extinction events become very common. In resume, population turnover outcomes on fixation rates of advantageous mutations are strongly influenced by the selective correlation among the subpopulations (demes).

Lens protein composition, glycation and high molecular weight aggregation in aging rats.

PubMed

Swamy, M S; Abraham, E C

1987-10-01

Because of minimal or no turnover, lens proteins are subjected to substantial post-translational modifications which in turn disrupt lens architecture and change the optical properties leading to senile cataract formation. Progressive glycation is believed to have the potential to initiate the changes that are conducive to lens opacification. Fisher 344 rats were systematically followed from juvenile to older and aged phases of their life to study the relationship between lens glycation and high molecular weight (HMW) aggregate formation as well as quantitative and qualitative changes in lens crystallins. Levels of glycated proteins were quantified by affinity chromatography. Changes in lens crystallin composition and HMW aggregate formation were monitored by molecular sieve HPLC, further confirmed by SDS-PAGE and IEF techniques. As the age advances HMW and insoluble proteins increase with a concomitant disappearance of gamma-crystallins from soluble fraction. This disappearance of gamma-crystallins coincided with increased glycation (approximately 2-fold higher in insoluble fraction) and decreased sulfhydryl groups from soluble fraction. It appears that lens protein glycation, disappearance of gamma-crystallins and sulfhydryls from soluble fraction and increase of insoluble fraction and HMW aggregate are interrelated.

Blocking the association of HDAC4 with MAP1S accelerates autophagy clearance of mutant Huntingtin

PubMed Central

Yue, Fei; Li, Wenjiao; Zou, Jing; Chen, Qi; Xu, Guibin; Huang, Hai; Xu, Zhen; Zhang, Sheng; Gallinari, Paola; Wang, Fen; McKeehan, Wallace L.; Liu, Leyuan

2015-01-01

Autophagy controls and executes the turnover of abnormally aggregated proteins. MAP1S interacts with the autophagy marker LC3 and positively regulates autophagy flux. HDAC4 associates with the aggregation-prone mutant huntingtin protein (mHTT) that causes Huntington's disease, and colocalizes with it in cytosolic inclusions. It was suggested HDAC4 interacts with MAP1S in a yeast two-hybrid screening. Here, we found that MAP1S interacts with HDAC4 via a HDAC4-binding domain (HBD). HDAC4 destabilizes MAP1S, suppresses autophagy flux and promotes the accumulation of mHTT aggregates. This occurs by an increase in the deacetylation of the acetylated MAP1S. Either suppression of HDAC4 with siRNA or overexpression of the MAP1S HBD leads to stabilization of MAP1S, activation of autophagy flux and clearance of mHTT aggregates. Therefore, specific interruption of the HDAC4-MAP1S interaction with short peptides or small molecules to enhance autophagy flux may relieve the toxicity of mHTT associated with Huntington's disease and improve symptoms of HD patients. PMID:26540094

Radioisotope tracer approach for understanding the impacts of global change-induced pedoturbation on soil C dynamics

NASA Astrophysics Data System (ADS)

Gonzalez-Meler, M. A.; Sturchio, N. C.; Sanchez-de Leon, Y.; Blanc-Betes, E.; Taneva, L.; Poghosyan, A.; Norby, R. J.; Filley, T. R.; Guilderson, T. P.; Welker, J. M.

2010-12-01

Biogeochemical carbon-cycle feedbacks to climate are apparent but uncertain, primarily because of gaps in mechanistic understanding on the ecosystem processes that drive carbon cycling and storage in terrestrial ecosystems, particularly in soils. Recent findings are increasingly recognizing the interaction between soil biota and the soil physical environment. Soil carbon turnover is partly determined by burial of organic matter and its physical and chemical protection. These factors are potentially affected by changes in climate (freezing-thawing or wet-drying cycles) or ecosystem structure including biological invasions. A major impediment to understanding dynamics of soil C in terrestrial systems is our inability to measure soil physical processes such as soil mixing rates or turnover of soil structures, including aggregates. Here we present a multiple radioisotope tracer approach (naturally occurring and man-made) to measure soil mixing rates in response to global change. We will present evidence of soil mixing rate changes in a temperate forest exposed to increased levels of atmospheric CO2 and in a tundra ecosystem exposed to increased thermal insulation. In both cases, radioisotope tracers proved to be an effective way to measure effects of global change on pedoturbation. Results also provided insights into the specific mechanisms involved in the responses. Elevated CO2 resulted in deeper soil mixing cells (increased by about 5cm on average) when compared to control soils as a consequence of changes in biota (increased root growth, higher earthworm density). In the tundra, soil warming induced higher rates of cryoturbation, resulting in what appears to be a net uplift of organic matter to the surface thereby exposing deeper C to decomposers. In both cases, global change factors affected the vertical distribution of C and changed the amount of bulk soil actively involved in soil processes. As a consequence, comparisons of C budgets to a given soil depth in response to global change factors may be misleading if they do not account for the depth change in the soil mixing cells.

7 CFR Exhibit B to Subpart I of... - Evaluation Report of Self-Help Technical Assistance (TA) Grants

Code of Federal Regulations, 2011 CFR

2011-01-01

...) f. Number of TA employees: (16) 6. a. Average time needed to construct a single house: (17) b... following adversely affect the Grantee's ability to accomplish program objectives? YES NO TA Staff Turnover ____ ____ FmHA Staff Turnover ____ ____ Bad Weather ____ ____ Loan Processing Delays ____ ____ Site Acquisition...

Hidden Casualties of Urban Teacher Turnover: Black Students Share Their Experiences

ERIC Educational Resources Information Center

Id-Deen, Lateefah

2016-01-01

Although teacher turnover affects many schools to some degree, it is especially problematic in urban settings (Ingersoll & Smith, 2003). This qualitative study examined the perspectives of five Black urban students who experienced a midyear teacher change in their 7th grade mathematics classroom. Findings suggest that these students were able…

7 CFR Exhibit B to Subpart I of... - Evaluation Report of Self-Help Technical Assistance (TA) Grants

Code of Federal Regulations, 2010 CFR

2010-01-01

...) f. Number of TA employees: (16) 6. a. Average time needed to construct a single house: (17) b... following adversely affect the Grantee's ability to accomplish program objectives? YES NO TA Staff Turnover ____ ____ FmHA Staff Turnover ____ ____ Bad Weather ____ ____ Loan Processing Delays ____ ____ Site Acquisition...

The Role of Organizational Learning Culture and Psychological Empowerment in Reducing Turnover Intention and Enhancing Citizenship Behavior

ERIC Educational Resources Information Center

Islam, Talat; Khan, Mubbsher Munawar; Bukhari, Fida Hussain

2016-01-01

Purpose: The purpose of this paper is to examine the association among organizational learning culture (OLC), psychological empowerment (PE), affective commitment (AC), organizational citizenship behavior and turnover intention. Design/Methodology/Approach: This study was undertaken via a questionnaire conducted among Malay-Chinese working in…

Earthworms and priming of soil organic matter - The impact of food sources, food preferences and fauna - microbiota interactions

NASA Astrophysics Data System (ADS)

Potthoff, Martin; Wichern, Florian; Dyckmans, Jens; Joergensen, Rainer Georg

2016-04-01

Earthworms deeply interact with the processes of soil organic matter turnover in soil. Stabilization of carbon by soil aggregation and in the humus fraction of SOM are well known processes related to earthworm activity and burrowing. However, recent research on priming effects showed inconsistent effects for the impact of earthworm activity. Endogeic earthworms can induce apparent as well as true positive priming effects. The main finding is almost always that earthworm increase the CO2 production from soil. The sources of this carbon release can vary and seem to depend on a complex interaction of quantity and quality of available carbon sources including added substrates like straw or other compounds, food preferences and feeding behavior of earthworms, and soil properties. Referring to recent studies on earthworm effects on soil carbon storage and release (mainly Eck et al. 2015 Priming effects of Aporrectodea caliginosa on young rhizodeposits and old soil organic matter following wheat straw addition, European Journal of Soil Biology 70:38-45; Zareitalabad et al. 2010 Decomposition of 15N-labelled maize leaves in soil affected by endogeic geophagous Aporrectodea caliginosa, Soil Biology and Biochemistry 42(2):276-282; and Potthoff et al. 2001 Short-term effects of earthworm activity and straw amendment on the microbial C and N turnover in a remoistened arable soil after summer drought, Soil Biology and Biochemistry 33(4):583-591) we summaries the knowledge on earthworms and priming and come up with a conceptual approach and further research needs.

Initial Soil Organic Matter Content Influences the Storage and Turnover of Litter-, Root- and Soil Carbon in Grasslands

NASA Astrophysics Data System (ADS)

Liu, L.; Xu, S.; Li, P.; Sayer, E. J.

2017-12-01

Grassland degradation is a worldwide problem that often leads to substantial loss of soil organic matter (SOM). Understanding how SOM content influences the stabilization of plant carbon (C) to form soil C is important to evaluate the potential of degraded grasslands to sequester additional C. We conducted a greenhouse experiment using C3 soils with six levels of SOM content and planted the C4 grass Cleistogenes squarrosa and/or added its litter to investigate how SOM content regulates the storage of new soil C derived from litter and roots, the decomposition of extant soil C, and the formation of soil aggregates. We found that microbial biomass carbon (MBC) increased with SOM content, and increased the mineralization of litter C. Both litter addition and planted treatments increased the amount of new C inputs to soil. However, litter addition had no significant impacts on the mineralization of extant soil C, but the presence of living roots significantly accelerated it. Thus, by the end of the experiment, soil C content was significantly higher in the litter addition treatments, but was not affected by planted treatments. The soil macroaggregate fraction increased with SOM content and was positively related to MBC. Overall, our study suggests that as SOM content increases, plant growth and soil microbes become more active, which allows microbes to process more plant-derived C and increases new soil C formation. The interactions between SOM content and plant C inputs should be considered when evaluating soil C turnover in degraded grasslands.

Landscape fragmentation affects responses of avian communities to climate change.

PubMed

Jarzyna, Marta A; Porter, William F; Maurer, Brian A; Zuckerberg, Benjamin; Finley, Andrew O

2015-08-01

Forecasting the consequences of climate change is contingent upon our understanding of the relationship between biodiversity patterns and climatic variability. While the impacts of climate change on individual species have been well-documented, there is a paucity of studies on climate-mediated changes in community dynamics. Our objectives were to investigate the relationship between temporal turnover in avian biodiversity and changes in climatic conditions and to assess the role of landscape fragmentation in affecting this relationship. We hypothesized that community turnover would be highest in regions experiencing the most pronounced changes in climate and that these patterns would be reduced in human-dominated landscapes. To test this hypothesis, we quantified temporal turnover in avian communities over a 20-year period using data from the New York State Breeding Atlases collected during 1980-1985 and 2000-2005. We applied Bayesian spatially varying intercept models to evaluate the relationship between temporal turnover and temporal trends in climatic conditions and landscape fragmentation. We found that models including interaction terms between climate change and landscape fragmentation were superior to models without the interaction terms, suggesting that the relationship between avian community turnover and changes in climatic conditions was affected by the level of landscape fragmentation. Specifically, we found weaker associations between temporal turnover and climatic change in regions with prevalent habitat fragmentation. We suggest that avian communities in fragmented landscapes are more robust to climate change than communities found in contiguous habitats because they are comprised of species with wider thermal niches and thus are less susceptible to shifts in climatic variability. We conclude that highly fragmented regions are likely to undergo less pronounced changes in composition and structure of faunal communities as a result of climate change, whereas those changes are likely to be greater in contiguous and unfragmented habitats. © 2015 John Wiley & Sons Ltd.

Comparative Proteome Analysis of hAT-MSCs Isolated from Chronic Renal Failure Patients with Differences in Their Bone Turnover Status.

PubMed

Kasap, Murat; Yeğenağa, Itır; Akpinar, Gurler; Tuncay, Mehmet; Aksoy, Ayça; Karaoz, Erdal

2015-01-01

The relationship between the stem cells and the bone turnover in uremic bone disease due to chronic renal failure (CRF) is not described. The aim of this study was to investigate the effect of bone turnover status on stem cell properties. To search for the presence of such link and shed some light on stem-cell relevant mechanisms of bone turnover, we carried out a study with mesenchymal stem cells. Tissue biopsies were taken from the abdominal subcutaneous adipose tissue of a CRF patient with secondary hyperparathyroidism with the high turnover bone disease. This patient underwent parathyroidectomy operation (PTX) and another sample was taken from this patient after PTX. A CRF patient with adynamic bone disease with low turnover and a healthy control were also included. Mesenchymal stem cells isolated from the subjects were analyzed using proteomic and molecular approaches. Except ALP activity, the bone turnover status did not affect common stem cell properties. However, detailed proteome analysis revealed the presence of regulated protein spots. A total of 32 protein spots were identified following 2D gel electrophoresis and MALDI-TOF/TOF analyzes. The identified proteins were classified into seven distinct groups and their potential relationship to bone turnover were discussed. Distinct protein expression patterns emerged in relation to the bone turnover status indicate a possible link between the stem cells and bone turnover in uremic bone disease due to CRF.

The Impact of Staff Turnover on Workplace Demands and Coworker Relationships

PubMed Central

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

[A study of work values, professional commitment, turnover intention and related factors among clinical nurses].

PubMed

Wang, Kuei-Ying; Chou, Chuan-Chiang; Huang, Jui-Lan

2010-02-01

The high rate of turnover in nursing positions is a global problem. There have been few studies done addressing the relationship between work values and nurse turnover intention. The purpose of this study was to explore the relationship between work values, professional commitment and turnover intention among clinical nurses. A cross-sectional survey was conducted between February 1st to March 10th, 2008 on a convenience sample of nurses, all of whom had at least a half year of work experience at one of four teaching hospitals in Taiwan. A total of 289 valid responses were received, with a response rate of 96.3%. Major findings included: (1) Nurses who were older, had more years of school, had worked more years, held specific job duties, earned a higher salary, held Buddhist beliefs, or were married with two or more children presented higher work values and professional commitment and lower turnover intention; (2) As a group, total work values and professional commitment scores corresponded negatively with turnover intention scores; (3) Significant factors affecting turnover intent in clinical nurses included professional commitment, institution characteristics, Buddhist beliefs and salary. These four variables accounted for 52.2% of the variation in turnover intention. This study indicated that nurses with higher work values and professional commitment tend to exhibit less turnover intention. It is highly recommended to develop strategies to bolster the teaching of altruistic values and professional commitment in nursing education in order to reduce turnover intent. Also, further studies on the influence of religious beliefs and organizational attributes on nurse turnover intentions are also suggested.

Workplace experiences and turnover intention among adult survivors of childhood cancer.

PubMed

Crom, Deborah B; Ness, Kirsten K; Martinez, Larry R; Hebl, Michelle R; Robison, Leslie L; Hudson, Melissa M; Brinkman, Tara M

2018-03-17

The purpose of this study was to investigate workplace experiences and turnover intention (consideration of leaving or changing a job) and to examine factors associated with turnover intention among survivors. Adult survivors of childhood cancer with a history of employment (n = 289) completed measures of workplace experiences (n = 50, 18-29 years; n = 183, 30-44 years; n = 56; > 45 years of age at follow-up). Turnover intention was assessed using three items from the Job Satisfaction Scale. Responses were dichotomized as reflecting high vs. low turnover intention. Path analysis was used to estimate the influence of demographic characteristics, treatment exposures (cranial radiation therapy [CRT]), and workplace experiences on turnover intention. Thirty percent of survivors reported high turnover intention (95% CL, 25 to 36%). Exposure to CRT (P = 0.003), older attained age (P < 0.001), experiencing formal workplace discrimination (P = 0.008), and having lower continuance (P < 0.001) or affective commitment (P < 0.001) were associated with high turnover intention among survivors. Informal discrimination, mediated through job satisfaction, also influenced survivors' reported intent to leave their jobs. One third of adult survivors of childhood cancer report turnover intention, which is related to their cancer treatment, but more temporally proximal, workplace discrimination. Additional research is needed to understand the consequences of turnover intention among survivors. Survivors and their health care providers should be aware of legislative policies related to workplace discrimination (e.g., American with Disabilities Act) and related implications for job turnover.

Drug-Free Platelets Can Act as Seeds for Aggregate Formation During Antiplatelet Therapy

PubMed Central

Hoefer, Thomas; Armstrong, Paul C.; Finsterbusch, Michaela; Chan, Melissa V.; Kirkby, Nicholas S.

2015-01-01

Objective— Reduced antiplatelet drug efficacy occurs in conditions of increased platelet turnover, associated with increased proportions of drug-free, that is, uninhibited, platelets. Here, we detail mechanisms by which drug-free platelets promote platelet aggregation in the face of standard antiplatelet therapy. Approach and Results— To model standard antiplatelet therapy, platelets were treated in vitro with aspirin, the P2Y12 receptor blocker prasugrel active metabolite, or aspirin plus prasugrel active metabolite. Different proportions of uninhibited platelets were then introduced. Light transmission aggregometry analysis demonstrated clear positive associations between proportions of drug-free platelets and percentage platelet aggregation in response to a range of platelet agonists. Using differential platelet labeling coupled with advanced flow cytometry and confocal imaging we found aggregates formed in mixtures of aspirin-inhibited platelets together with drug-free platelets were characterized by intermingled platelet populations. This distribution is in accordance with the ability of drug-free platelets to generate thromboxane A2 and so drive secondary platelet activation. Conversely, aggregates formed in mixtures of prasugrel active metabolite–inhibited or aspirin plus prasugrel active metabolite–inhibited platelets together with drug-free platelets were characterized by distinct cores of drug-free platelets. This distribution is consistent with the ability of drug-free platelets to respond to the secondary activator ADP. Conclusions— These experiments are the first to image the interactions of inhibited and uninhibited platelets in the formation of platelet aggregates. They demonstrate that a general population of platelets can contain subpopulations that respond strikingly differently to overall stimulation of the population and so act as the seed for platelet aggregation. PMID:26272940

Concurrent and lagged effects of registered nurse turnover and staffing on unit-acquired pressure ulcers.

PubMed

Park, Shin Hye; Boyle, Diane K; Bergquist-Beringer, Sandra; Staggs, Vincent S; Dunton, Nancy E

2014-08-01

We examined the concurrent and lagged effects of registered nurse (RN) turnover on unit-acquired pressure ulcer rates and whether RN staffing mediated the effects. Quarterly unit-level data were obtained from the National Database of Nursing Quality Indicators for 2008 to 2010. A total of 10,935 unit-quarter observations (2,294 units, 465 hospitals) were analyzed. This longitudinal study used multilevel regressions and tested time-lagged effects of study variables on outcomes. The lagged effect of RN turnover on unit-acquired pressure ulcers was significant, while there was no concurrent effect. For every 10 percentage-point increase in RN turnover in a quarter, the odds of a patient having a pressure ulcer increased by 4 percent in the next quarter. Higher RN turnover in a quarter was associated with lower RN staffing in the current and subsequent quarters. Higher RN staffing was associated with lower pressure ulcer rates, but it did not mediate the relationship between turnover and pressure ulcers. We suggest that RN turnover is an important factor that affects pressure ulcer rates and RN staffing needed for high-quality patient care. Given the high RN turnover rates, hospital and nursing administrators should prepare for its negative effect on patient outcomes. © Health Research and Educational Trust.

Concurrent and Lagged Effects of Registered Nurse Turnover and Staffing on Unit-Acquired Pressure Ulcers

PubMed Central

Park, Shin Hye; Boyle, Diane K; Bergquist-Beringer, Sandra; Staggs, Vincent S; Dunton, Nancy E

2014-01-01

Objective We examined the concurrent and lagged effects of registered nurse (RN) turnover on unit-acquired pressure ulcer rates and whether RN staffing mediated the effects. Data Sources/Setting Quarterly unit-level data were obtained from the National Database of Nursing Quality Indicators for 2008 to 2010. A total of 10,935 unit-quarter observations (2,294 units, 465 hospitals) were analyzed. Methods This longitudinal study used multilevel regressions and tested time-lagged effects of study variables on outcomes. Findings The lagged effect of RN turnover on unit-acquired pressure ulcers was significant, while there was no concurrent effect. For every 10 percentage-point increase in RN turnover in a quarter, the odds of a patient having a pressure ulcer increased by 4 percent in the next quarter. Higher RN turnover in a quarter was associated with lower RN staffing in the current and subsequent quarters. Higher RN staffing was associated with lower pressure ulcer rates, but it did not mediate the relationship between turnover and pressure ulcers. Conclusions We suggest that RN turnover is an important factor that affects pressure ulcer rates and RN staffing needed for high-quality patient care. Given the high RN turnover rates, hospital and nursing administrators should prepare for its negative effect on patient outcomes. PMID:24476194

An analysis of restructuring orientation to enhance nurse retention.

PubMed

Kiel, Joan M

2012-01-01

The nursing shortage has received much media attention; however, something that contributes to it-nurse turnover-has not received the same attention. Facilities spend time and money to train new employees only to have them leave within a few months. Staff morale, money, time, and quality of care are all affected by nurse turnover. The fact that it often occurs so soon after one takes a position makes it pertinent to look at the process of transition into the new position, namely, the orientation program. This article examines the turnover statistics, costs, rationale, and orientation programs that have proven positive results. It is hoped that the findings can assist health care facilities to replicate successful orientation programs and reduce nurse turnover.

7 CFR 51.1564 - External defects.

Code of Federal Regulations, 2012 CFR

2012-01-01

... percent of the surface in the aggregate. Growth Cracks When the growth crack(s) affects more than 1/2 the... growth crack(s) affects more than 3/4 the length of the potato in the aggregate or when the depth is... 25 percent of the surface in the aggregate is affected. Second Growth When materially detracting from...

Factors Affecting the Retention of First-Career and Second-Career Science Teachers in Urban High Schools

ERIC Educational Resources Information Center

Rak, Rosemary C.

2013-01-01

The turnover of high school science teachers is an especially troubling problem in urban schools with economically disadvantaged students. Because high teacher turnover rates impede effective instruction, the persistence of teacher attrition is a serious concern. Using an online survey and interviews in a sequential mixed-methods approach, this…

The Effects of Turnover: What We Know about Teacher Attrition

ERIC Educational Resources Information Center

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:…

Elevated CO2 and water addition enhance nitrogen turnover in grassland plants with implications for temporal stability

USDA-ARS?s Scientific Manuscript database

In most terrestrial ecosystems, nitrogen (N) is scarce and therefore economical use of N by plants will affect their fitness. Plants continuously take up and lose N, but can reduce this N turnover by recycling N internally through resorption and reallocation, which may be more economical when extern...

The short-term effects of cisplatin chemotherapy on bone turnover.

PubMed

Young, D R; Virolainen, P; Inoue, N; Frassica, F J; Chao, E Y

1997-11-01

Cisplatin is an effective agent in the treatment of osteosarcoma of bone but little is known of its effects on normal bone turnover. Twenty-four dogs divided into three study groups were used to study the effect of cisplatin on normal bone turnover at the distant site of surgery. Group 1 served as the control group, group 2 received four cycles of cisplatin every 3 weeks before the surgery, and group 3 received four cycles postoperatively. The bone turnover rate was evaluated by measuring levels of systemic bone markers, osteocalcin, alkaline phospohatase, urine pyridinoline cross-links, and by determination histomorphometric indices. Histomorphological analysis showed poor correlation on bone formation with systemic bone markers at distant sites of surgery. Histomorphometrically normal bone turnover was affected by administration of cisplatin, but the effect was temporary, late, and less significant than what occurred at the surgical site. Our data showed that significant effects of cisplatin are observed at the site of active cellular induction and proliferation, such as implant-host interface, and less effects are seen at the sites of normal bone turnover.

Turnover and vacancy rates for registered nurses: do local labor market factors matter?

PubMed

Rondeau, Kent V; Williams, Eric S; Wagar, Terry H

2008-01-01

Turnover of nursing staff is a significant issue affecting health care cost, quality, and access. In recent years, a worldwide shortage of skilled nurses has resulted in sharply higher vacancy rates for registered nurses in many health care organizations. Much research has focused on the individual, group, and organizational determinants of turnover. Labor market factors have also been suggested as important contributors to turnover and vacancy rates but have received limited attention by scholars. This study proposes and tests a conceptual model showing the relationships of organization-market fit and three local labor market factors with organizational turnover and vacancy rates. The model is tested using ordinary least squares regression with data collected from 713 Canadian hospitals and nursing homes. Results suggest that, although modest in their impact, labor market and the organization-market fit factors do make significant yet differential contributions to turnover and vacancy rates for registered nurses. Knowledge of labor market factors can substantially shape an effective campaign to recruit and retain nurses. This is particularly true for employers who are perceived to be "employers-of-choice."

An analysis of carbon and radiocarbon profiles across a range ecosystems types

NASA Astrophysics Data System (ADS)

Heckman, K. A.; Gallo, A.; Hatten, J. A.; Swanston, C.; Strahm, B. D.; Sanclements, M.

2016-12-01

Soil carbon stocks have become recognized as increasingly important in the context of climate change and global C cycle modeling. As modelers seek to identify key parameters affecting the size and stability of belowground C stocks, attention has been drawn to the mineral matrix and the soil physiochemical factors influenced by it. Though clay content has often been utilized as a convenient and key explanatory variable for soil C dynamics, its utility has recently come under scrutiny as new paradigms of soil organic matter stabilization have been developed. We utilized soil cores from a range of National Ecological Observatory Network (NEON) experimental plots to examine the influence of mineralogical parameters on soil C stocks and turnover and their relative importance in comparison to climatic variables. Results are presented for a total of 11 NEON sites, spanning Alfisols, Entisols, Mollisols and Spodosols. Soils were sampled by genetic horizon, density separated according to density fractionation: light fractions (particulate organics neither occluded within aggregates nor associated with mineral surfaces), occluded fractions (particulate organics occluded within aggregates), and heavy fractions (organics associated with mineral surfaces). Bulk soils and density fractions were measured for % C and radiocarbon abundance (as a measure of C stability). Carbon and radiocarbon abundances were examined among fractions and in the context of climatic variables (temperature, precipitation, elevation) and soil physiochemical variables (% clay and pH). No direct relationships between temperature and soil C or radiocarbon abundances were found. As a whole, soil radiocarbon abundance in density fractions decreased in the order of light>heavy>occluded, highlighting the importance of both surface sorption and aggregation to the preservation of organics. Radiocarbon concentrations of the heavy fraction (mineral adsorbed) were significantly, though weakly, correlated with pH (r2 = 0.35, p = 0.02), though C concentrations were not. Data suggest an important role for both aggregation and soil chemistry in regulating soil C cycling across a diversity of soil orders. The current presented results serve as a preliminary report on a project spanning 40 NEON sites and a range of physiochemical analyses.

The Every Student Succeeds Act, State Efforts to Improve Access to Effective Educators, and the Importance of School Leadership

ERIC Educational Resources Information Center

Fuller, Edward J.; Hollingworth, Liz; Pendola, Andrew

2017-01-01

Purpose: Our primary purpose is to examine the degree to which state equity plans identify the distribution of principals and principal turnover as factors influencing three leadership mechanisms that affect student access to effective teachers--namely, hiring of teachers, building instructional capacity of teachers, and managing teacher turnover.…

Causes of Job Turnover in the Public School Superintendency: An Explanatory Analysis in the Western United States

ERIC Educational Resources Information Center

Melver, Toby A.

2011-01-01

The purpose of this mixed-methods study was to determine the factors that affect public school superintendent turnover in five western states. An explanatory theory was developed to cover all of the possible variables and show the relationship between those variables. The questions that guided this research study were: (1) What environmental…

Teacher Satisfaction and Turnover in Charter Schools: Examining the Variations and Possibilities for Collective Bargaining in State Laws

ERIC Educational Resources Information Center

Torres, A. Chris; Oluwole, Joseph

2015-01-01

Charter schools see as many as one in four teachers leave annually, and recent evidence attributes much of this turnover to provisions affected by collective bargaining processes and state laws such as salary, benefits, job security, and working hours. There have been many recent efforts to improve teacher voice in charter schools (Kahlenberg…

Assessment of Staff Retention in Private Universities in Ghana: A Study of the Perez University College, Winneba

ERIC Educational Resources Information Center

Kwegyir-Aggrey, Peter

2016-01-01

Staff turnover especially among lecturers in private universities is high due to poor and disappointing conditions of service. This negatively affects effective teaching, learning and research. The purpose of the study was to examine the causes of staff turnover in private universities, using the Perez University College in Winneba as a case…

Increased precipitation accelerates soil organic matter turnover associated with microbial community composition in topsoil of alpine grassland on the eastern Tibetan Plateau.

PubMed

Han, Conghai; Wang, Zongli; Si, Guicai; Lei, Tianzhu; Yuan, Yanli; Zhang, Gengxin

2017-10-01

Large quantities of carbon are stored in alpine grassland of the Tibetan Plateau, which is extremely sensitive to climate change. However, it remains unclear whether soil organic matter (SOM) in different layers responds to climate change analogously, and whether microbial communities play vital roles in SOM turnover of topsoil. In this study we measured and collected SOM turnover by the 14 C method in alpine grassland to test climatic effects on SOM turnover in soil profiles. Edaphic properties and microbial communities in the northwestern Qinghai Lake were investigated to explore microbial influence on SOM turnover. SOM turnover in surface soil (0-10 cm) was more sensitive to precipitation than that in subsurface layers (10-40 cm). Precipitation also imposed stronger effects on the composition of microbial communities in the surface layer than that in deeper soil. At the 5-10 cm depth, the SOM turnover rate was positively associated with the bacteria/fungi biomass ratio and the relative abundance of Acidobacteria, both of which are related to precipitation. Partial correlation analysis suggested that increased precipitation could accelerate the SOM turnover rate in topsoil by structuring soil microbial communities. Conversely, carbon stored in deep soil would be barely affected by climate change. Our results provide valuable insights into the dynamics and storage of SOM in alpine grasslands under future climate scenarios.

Aggregated low-density lipoprotein induces LRP1 stabilization through E3 ubiquitin ligase CHFR downregulation in human vascular smooth muscle cells.

PubMed

Cal, Roi; García-Arguinzonis, Maisa; Revuelta-López, Elena; Castellano, José; Padró, Teresa; Badimon, Lina; Llorente-Cortés, Vicenta

2013-02-01

Low density lipoprotein retention and aggregation in the arterial intima are key processes in atherogenesis. Aggregated LDL (agLDL) is taken up through low-density lipoprotein receptor-related protein 1 (LRP1) by human vascular smooth muscle cells (VSMC). AgLDL increases LRP1 expression, at least in part, by downregulation of sterol regulatory element-binding proteins. It is unknown whether agLDL has some effect on the ubiquitin-proteasome system, and therefore on the LRP1 receptor turnover. The objective of this study was to analyze the effect of agLDL on the degradation of LRP1 by the ubiquitin-proteasome system in human VSMC. Human VSMC were isolated from the media of human coronary arteries. Ubiquitinylated LRP1 protein levels were significantly reduced in human VSMC exposed to agLDL (100 μg/mL) for 20 hours (agLDL: 3.70±0.44 a.u. versus control: 9.68±0.55 a.u). Studies performed with cycloheximide showed that agLDL prolongs the LRP1 protein half life. Pulse-chase analysis showed that LRP1 turnover rate is reduced in agLDL-exposed VSMC. Two-dimensional electrophoresis shows an alteration in the proteomic profile of a RING type E3 ubiquitin ligase, CHFR. Real-time PCR and Western blot analysis showed that agLDL (100 μg/mL) decreased the transcriptional and protein expression of CHFR. CHFR silencing increased VSMC, but not macrophage, LRP1 expression. However, CHFR silencing did not exert any effect on the classical low-density lipoprotein receptor protein levels. Furthermore, immunoprecipitation experiments demonstrated that the physical interaction between CHFR and LRP1 decreased in the presence of agLDL. Our results demonstrate that agLDL prolongs the half life of LRP1 by preventing the receptor ubiquitinylation, at least in part, through CHFR targeting. This mechanism seems to be specific for LRP1 and VSMC.

Job satisfaction and turnover intention among Iraqi doctors--a descriptive cross-sectional multicentre study.

PubMed

Ali Jadoo, Saad Ahmed; Aljunid, Syed Mohamed; Dastan, Ilker; Tawfeeq, Ruqiya Subhi; Mustafa, Mustafa Ali; Ganasegeran, Kurubaran; AlDubai, Sami Abdo Radman

2015-04-19

During the last two decades, the Iraqi human resources for health was exposed to an unprecedented turnover of trained and experienced medical professionals. This study aimed to explore prominent factors affecting turnover intentions among Iraqi doctors. A descriptive cross-sectional multicentre study was carried out among 576 doctors across 20 hospitals in Iraq using multistage sampling technique. Participants completed a self-administered questionnaire, which included socio-demographic information, work characteristics, the 10-item Warr-Cook-Wall job satisfaction scale, and one question on turnover intention. Descriptive and bivariate and multiple logistic regression analyses were conducted to identify significant factors affecting turnover intentions. More than one half of Iraqi doctors (55.2%) were actively seeking alternative employment. Factors associated with turnover intentions among doctors were low job satisfaction score (odds ratio (OR) = 0.97; 95% confidence interval (CI): 0.95, 0.99), aged 40 years old or less (OR = 2.9; 95% CI: 1.74, 4.75), being male (OR = 4.2; 95% CI: 2.54, 7.03), being single (OR = 5.0; 95% CI: 2.61, 9.75), being threatened (OR = 3.5; 95% CI: 1.80, 6.69), internally displaced (OR = 3.1; 95% CI: 1.43, 6.57), having a perception of unsafe medical practice (OR = 4.1; 95% CI: 1.86, 9.21), working more than 40 h per week, (OR = 2.3; 95% CI: 1.27, 4.03), disagreement with the way manager handles staff (OR = 2.2; 95% CI: 1.19, 4.03), being non-specialist, (OR = 3.9, 95% CI: 2.08, 7.13), and being employed in the government sector only (OR = 2.0; 95% CI: 1.09, 3.82). The high-turnover intention among Iraqi doctors is significantly associated with working and security conditions. An urgent and effective strategy is required to prevent doctors' exodus.

Simulation of soil organic carbon in different soil size fractions using 13Carbon measurement data

NASA Astrophysics Data System (ADS)

Gottschalk, P.; Bellarby, J.; Chenu, C.; Foereid, B.; Wattenbach, M.; Zingore, S.; Smith, J.

2009-04-01

We simulate the soil organic carbon (SOC) dynamics at a chronoseqeunce site in France, using the Rothamsted Carbon model. The site exhibits a transition from C3 plants, dominated by pine forest, to a conventional C4 maize rotation. The different 13C signatures of the forest plants and maize are used to distinguish between the woodland derived carbon (C) and the maize derived C. The model is evaluated against total SOC and C derived from forest and maize, respectively. The SOC dynamics of the five SOC pools of the model, decomposable plant material (DPM), resistant plant material (RPM), biomass, humus and inert C, are also compared to the SOC dynamics measured in different soil size fractions. These fractions are > 50 μm (particulate organic matter), 2-50 μm (silt associated SOC) and <2 μm (clay associated SOC). Other authors had shown that the RPM pool of the model corresponds well to SOC measured in the soil size fraction > 50 μm and the sum of the other pools corresponds well to the SOC measured in the soil size fraction < 50 μm. Default model applications show that the model underestimates the fast drop in forest C stocks in the first 20 years after land-use change and overestimates the C accumulation of maize C. Several hypotheses were tested to evaluate the simulations. Input data and internal model parameter uncertainties had minor effects on the simulations results. Accounting for erosion and implementing a simple tillage routine did not improve the simulation fit to the data. We therefore hypothesize that a generic process that is not yet explicitly accounted for in the ROTHC model could explain the loss in soil C after land use change. Such a process could be the loss of the physical protection of soil organic matter as would be observed following cultivation of a previously uncultivated soil. Under native conditions a fraction of organic matter is protected in stable soil aggregates. These aggregates are physically disrupted by continuous and repeated cultivation of the soil. The underestimation of SOC loss by the model can be mainly attributed to the slow turnover of the humus pool. This pool was shown to represent mainly the SOC associated with the silt and clay soil fraction. Here, the clay associated SOC shows as similar turnover time as the humus pool in the model. We split the humus pool into a clay and a silt associated pool. The clay pool now corresponds to the clay associated SOC with the turnover time of the humus pool. The silt pool now corresponds to the silt associated SOC. From the measurements, the latter has a turnover time similar to the turnover time of the particulate organic matter. We therefore use the turnover time of the RPM pool for the silt pool. These modifications improve the simulations of the forest derived C significantly and improve the simulations of the maize derived C. Future work will further evaluate and refine this approach to eventually capture the SOC dynamics associated with physical protection, including the effect of tillage/no-tillage, in a simple approach.

[Path analysis on workplace violence affecting work ability, job satisfaction and turnover intent in health professionals in Shangqiu City].

PubMed

Wang, Pei-xi; Wang, Mian-zhen; Bai, Qin; Jia, Cai-feng; Lan, Ya-jia; Wang, Zhi-ming; Luan, Rong-sheng

2006-11-01

To explore the effects of workplace violence on work ability, work satisfaction and turnover intent based on the theory of occupational stress in health professionals and to provide evidence for evaluating the process and consequence of workplace violence. Subjects of 483 health professionals from 5 hospitals in Shangqiu city of Hennan Province were selected with stratified cluster random sampling method. Workplace violence, violent fear at work, coping resources, work ability, job satisfaction and turnover intent were measured with questionnaires. Ordinal regression analysis and path analysis were applied to analyze the data. Workplace violence had direct or indirect effects on the work ability and job satisfaction through the fear of future violence at work. Workplace violence only had indirect effects on turnover intent through the fear and job satisfaction in health professionals. Workplace violence had direct and indirect effects on the work ability, job satisfaction and turnover intent. Measures should be taken to reduce workplace violence and it' s effects in health professionals.

An assessment of safety climate, job satisfaction and turnover intention relationships using a national sample of workers from the USA.

PubMed

Smith, Todd D

2018-03-01

The association between safety climate, job satisfaction and turnover intention has not been thoroughly researched. This research is needed so that safety researchers and practitioners can begin to delineate the impact of safety on organizational and business outcomes. A path analysis was completed using data from a national sample of workers from the USA (n = 1525). The overall fit of the model was excellent and analyses determined that both training and resource adequacy positively affected safety climate and job satisfaction. Safety climate also positively influenced job satisfaction. Both safety climate and job satisfaction were negatively associated with respondents' turnover intention. In the study, the relationship between job satisfaction and turnover intention is reiterated in a sample of workers across many industries. This study is novel because it is one of the first studies to confirm that turnover intention is reduced with increased safety climate in a diverse sample of workers.

Coupling of kinesin ATP turnover to translocation and microtubule regulation: one engine, many machines.

PubMed

Friel, Claire T; Howard, Jonathon

2012-12-01

The cycle of ATP turnover is integral to the action of motor proteins. Here we discuss how variation in this cycle leads to variation of function observed amongst members of the kinesin superfamily of microtubule associated motor proteins. Variation in the ATP turnover cycle among superfamily members can tune the characteristic kinesin motor to one of the range of microtubule-based functions performed by kinesins. The speed at which ATP is hydrolysed affects the speed of translocation. The ratio of rate constants of ATP turnover in relation to association and dissociation from the microtubule influence the processivity of translocation. Variation in the rate-limiting step of the cycle can reverse the way in which the motor domain interacts with the microtubule producing non-motile kinesins. Because the ATP turnover cycle is not fully understood for the majority of kinesins, much work remains to show how the kinesin engine functions in such a wide variety of molecular machines.

The effects of the ARC organizational intervention on caseworker turnover, climate, and culture in children's service systems.

PubMed

Glisson, Charles; Dukes, Denzel; Green, Philip

2006-08-01

This study examines the effects of the Availability, Responsiveness, and Continuity (ARC) organizational intervention strategy on caseworker turnover, climate, and culture in a child welfare and juvenile justice system. Using a pre-post, randomized blocks, true experimental design, 10 urban and 16 rural case management teams were randomly assigned to either the ARC organizational intervention condition or to a control condition. The culture and climate of each case management team were assessed at baseline and again after the one-year organizational intervention was completed. In addition, caseworker turnover was assessed by identifying caseworkers on the sampled teams who quit their jobs during the year. Hierarchical Linear Models (HLM) analyses indicate that the ARC organizational intervention reduced the probability of caseworker turnover by two-thirds and improved organizational climate by reducing role conflict, role overload, emotional exhaustion, and depersonalization in both urban and rural case management teams. Organizational intervention strategies can be used to reduce staff turnover and improve organizational climates in urban and rural child welfare and juvenile justice systems. This is important because child welfare and juvenile justice systems in the U.S.A. are plagued by high turnover rates, and there is evidence that high staff turnover and poor organizational climates negatively affect service quality and outcomes in these systems.

Impact of organisational characteristics on turnover intention among care workers in nursing homes in Korea: a structural equation model.

PubMed

Ha, Jong Goon; Man Kim, Ji; Hwang, Won Ju; Lee, Sang Gyu

2014-09-01

The aim of the present study was to analyse the impact of organisational characteristics on the turnover intention of care workers working at nursing homes in Korea. Study participants included 504 care workers working at 14 nursing homes in Korea. The variables measured were: high-performance work practices, consisting of five subfactors (official training, employment stability, autonomy, employee participation and group-based payment); organisational commitment, consisting of three subfactors (affective, normative and continuance commitment); organisational support; and turnover intention. The inter-relationship between high-performance work practices, organisational support, organisational commitment and turnover intention and the fit of the hypothetical model were analysed using structural equation modelling. According to our analysis, high-performance work practices not only had a direct effect on turnover intention, but also an indirect effect by mediating organisational support and commitment. The factor having the largest direct influence on turnover intention was organisational commitment. The results of the present study suggest that to improve health conditions for frail elderly patients at nursing homes, as well as the efficiency of nursing homes through the continuance of nursing service and enhancement of quality of service, long-term care facilities should reduce the turnover intention of care workers by increasing their organisational commitment by actively implementing high-performance work practices.

Afforestation impacts microbial biomass and its natural (13)C and (15)N abundance in soil aggregates in central China.

PubMed

Wu, Junjun; Zhang, Qian; Yang, Fan; Lei, Yao; Zhang, Quanfa; Cheng, Xiaoli

2016-10-15

We investigated soil microbial biomass and its natural abundance of δ(13)C and δ(15)N in aggregates (>2000μm, 250-2000μm, 53-250μm and <53μm) of afforested (implementing woodland and shrubland plantations) soils, adjacent croplands and open area (i.e., control) in the Danjiangkou Reservoir area of central China. The afforested soils averaged higher microbial biomass carbon (MBC) and nitrogen (MBN) levels in all aggregates than in open area and cropland, with higher microbial biomass in micro-aggregates (<250μm) than in macro-aggregates (>2000μm). The δ(13)C of soil microbial biomass was more enriched in woodland soils than in other land use types, while δ(15)N of soil microbial biomass was more enriched compared with that of organic soil in all land use types. The δ(13)C and δ(15)N of microbial biomass were positively correlated with the δ(13)C and δ(15)N of organic soil across aggregates and land use types, whereas the (13)C and (15)N enrichment of microbial biomass exhibited linear decreases with the corresponding C:N ratio of organic soil. Our results suggest that shifts in the natural (13)C and (15)N abundance of microbial biomass reflect changes in the stabilization and turnover of soil organic matter (SOM) and thereby imply that afforestation can greatly impact SOM accumulation over the long-term. Copyright © 2016 Elsevier B.V. All rights reserved.

Turnover intentions in a call center: The role of emotional dissonance, job resources, and job satisfaction.

PubMed

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.

Global covariation of carbon turnover times with climate in terrestrial ecosystems.

PubMed

Carvalhais, Nuno; Forkel, Matthias; Khomik, Myroslava; Bellarby, Jessica; Jung, Martin; Migliavacca, Mirco; Mu, Mingquan; Saatchi, Sassan; Santoro, Maurizio; Thurner, Martin; Weber, Ulrich; Ahrens, Bernhard; Beer, Christian; Cescatti, Alessandro; Randerson, James T; Reichstein, Markus

2014-10-09

The response of the terrestrial carbon cycle to climate change is among the largest uncertainties affecting future climate change projections. The feedback between the terrestrial carbon cycle and climate is partly determined by changes in the turnover time of carbon in land ecosystems, which in turn is an ecosystem property that emerges from the interplay between climate, soil and vegetation type. Here we present a global, spatially explicit and observation-based assessment of whole-ecosystem carbon turnover times that combines new estimates of vegetation and soil organic carbon stocks and fluxes. We find that the overall mean global carbon turnover time is 23(+7)(-4) years (95 per cent confidence interval). On average, carbon resides in the vegetation and soil near the Equator for a shorter time than at latitudes north of 75° north (mean turnover times of 15 and 255 years, respectively). We identify a clear dependence of the turnover time on temperature, as expected from our present understanding of temperature controls on ecosystem dynamics. Surprisingly, our analysis also reveals a similarly strong association between turnover time and precipitation. Moreover, we find that the ecosystem carbon turnover times simulated by state-of-the-art coupled climate/carbon-cycle models vary widely and that numerical simulations, on average, tend to underestimate the global carbon turnover time by 36 per cent. The models show stronger spatial relationships with temperature than do observation-based estimates, but generally do not reproduce the strong relationships with precipitation and predict faster carbon turnover in many semi-arid regions. Our findings suggest that future climate/carbon-cycle feedbacks may depend more strongly on changes in the hydrological cycle than is expected at present and is considered in Earth system models.

Turnover intentions in a call center: The role of emotional dissonance, job resources, and job satisfaction

PubMed Central

Zito, Margherita; Molino, Monica; Cortese, Claudio Giovanni; Ghislieri, Chiara; Colombo, Lara

2018-01-01

Background 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. Method 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 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. Conclusion 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. PMID:29401507

Nursing home spending, staffing, and turnover.

PubMed

Kash, Bita A; Castle, Nicholas G; Phillips, Charles D

2007-01-01

Recent work on nursing home staffing and turnover has stressed the importance of ownership and resources. However, few studies have examined spending behaviors, which might also influence staffing levels and staff turnover rates. This study investigates whether spending behaviors measured by financial ratios are associated with staffing levels and staff turnover in nursing homes. We analyzed cross-sectional data from 1,014 Texas homes. Data were from the 2002 Texas Nursing Facility Medicaid Cost Report and the 2003 Area Resource File. First, we examined differences in financial ratios by ownership type. Next, the effect of 10 financial ratios on staffing levels and turnover rates for registered nurses, licensed vocational nurses, and certified nursing assistants was examined using robust regression models. Descriptive data indicated that expense ratios related to resident care activities and staff development were significantly higher among not-for-profit than for-profit homes. Higher profits were associated with lower staffing levels, but not higher turnover rates. Administrative expenses (a measure of management capacity) had a negative impact both on staffing levels and staff turnover for licensed vocational nurses and certified nursing assistants, but they did not affect registered nurse staffing. Employee benefit expenses exhibited a positive impact on registered nurse and licensed vocational nurse staffing levels. The addition of information on financial ratios to models predicting staffing indicators reduced the effect of ownership on these indicators. Solutions to the staffing and turnover problem should focus on more effective management practices. Certain levels of administrative and staff benefit expenses may be necessary to improve professional staff recruitment and reduce both staffing and turnover costs. Differences in these financial ratios may partially explain the role played by ownership in determining staffing levels and turnover.

Divergent environmental filters drive functional segregation of European peatlands

NASA Astrophysics Data System (ADS)

Robroek, B.; Jassey, V.; Bragazza, L.; Buttler, A.

2015-12-01

Plant communities are largely shaped by prevailing climatic conditions. As a result, environmental change is expected to alter the (functional) composition in plant communities. Because plants, and particularly the composition of plant species, play an important role in driving ecosystem processes, it is crucial that we improve our understanding on which environmental factors are most important in shaping plant communities. Here we presnt the results for a cross-Eurpean study, were we assessed the role of environmnetal conditions on plant community composition in 56 peatlands. We show that plant species richness and diversity are relatively stable across the main environmental gradients. Nevertheless, we observe large changes in the plant community structure. In other words, species turnover increased with increasing differences in environmental viariables. Such turnover in the community composition is largely associated to gradients temperature and precipitation, whilst nutrients -often reported as major driver for changes in peatland ecosystems- were only important at the end of the gradient of current deposition levels in Europe. Using a combination of species distribution modelling and species co-occurence patterns, we identified two spatially non-exclusive groups of plant species. Species within a distinct group responded similarly to bioclimatic variables and nutrient deposition levels, whilst between group response was mirrored. These results suggest that these two groups of plants are subjected to divergent environmental filters. Additionally, European peatlands aggregate into two distinct clusters based on plant functional trait composition. Each cluster was dominated by plant species from either one of the two co-response groups. Overall, our results demonstrate that environmental change results in a gradual replacement of plant species from two divergent groups, consequently affecting the functional trait composition in peatlands.

The roles of unit leadership and nurse-physician collaboration on nursing turnover intention.

PubMed

Galletta, Maura; Portoghese, Igor; Battistelli, Adalgisa; Leiter, Michael P

2013-08-01

To report a study of the relationship between variables at the group and individual level with nurses' intention to leave their unit. Workplaces are collective environments where workers constantly interact with each other. The quality of working relationship employees develop at the unit-level influences both employee outcomes and unit performance by shaping employee attitudes. The study was a cross-sectional design with self-administered questionnaires. A questionnaire including measures of leader-member exchange and nurse-physician collaboration analysed at group-level and affective commitment and turnover intention analysed at individual level, was administered individually to 1018 nurses in five Italian hospitals. Data were collected in 2009. A total of 832 nurses (81·7% response rate) completed questionnaires. The results showed that affective commitment at individual level completely mediated the relationship between leader-member exchange at group-level and nursing turnover intention. Furthermore, the cross-level interaction was significant: at individual level, the nurses with high levels of individual affective commitment towards their unit showed low levels of turnover intention and this relationship was stronger when the nurse-physician collaboration at group-level was high. This study showed the importance for organizations to implement management practices that promote both high-quality nurse-supervisor and nurse-physician relationships, because they increase nurses' identification with their units. Individual affective commitment is an important quality for retaining a workforce and good nurses' relationship at group-level relationships with both supervisors and physicians are instrumental in developing identification with the work unit. Thus, the quality of relationship among staff members is an important factor in nurses' decision to leave. © 2012 Blackwell Publishing Ltd.

An Analysis of Factors Affecting Affiliation in the Marine Corps Reserves

DTIC Science & Technology

2014-12-01

AR Active Reserve ASL Active Status List CC Continuance Commitment DODI Department of Defense Instruction DON Department of the Navy FFM ...turnover (Mobley, Griffeth, Hand, & Meglino, 1979). Other research on personality constructs use the five factor model ( FFM ) as a basis...Conscientiousness and emotional stability are two personality dimensions of the FFM , which are negatively correlated and useful predictors of voluntary turnover

Assessing Soil Organic C Stability at the Continental Scale: An Analysis of Soil C and Radiocarbon Profiles Across the NEON Sites

NASA Astrophysics Data System (ADS)

Heckman, K. A.; Gallo, A.; Hatten, J. A.; Swanston, C.; McKnight, D. M.; Strahm, B. D.; Sanclements, M.

2017-12-01

Soil carbon stocks have become recognized as increasingly important in the context of climate change and global C cycle modeling. As modelers seek to identify key parameters affecting the size and stability of belowground C stocks, attention has been drawn to the mineral matrix and the soil physiochemical factors influenced by it. Though clay content has often been utilized as a convenient and key explanatory variable for soil C dynamics, its utility has recently come under scrutiny as new paradigms of soil organic matter stabilization have been developed. We utilized soil cores from a range of National Ecological Observatory Network (NEON) experimental plots to examine the influence of physicochemical parameters on soil C stocks and turnover, and their relative importance in comparison to climatic variables. Soils were cored at NEON sites, sampled by genetic horizon, and density separated into light fractions (particulate organics neither occluded within aggregates nor associated with mineral surfaces), occluded fractions (particulate organics occluded within aggregates), and heavy fractions (organics associated with mineral surfaces). Bulk soils and density fractions were measured for % C and radiocarbon abundance (as a measure of C stability). Carbon and radiocarbon abundances were examined among fractions and in the context of climatic variables (temperature, precipitation, elevation) and soil physiochemical variables (% clay and pH). No direct relationships between temperature and soil C or radiocarbon abundances were found. As a whole, soil radiocarbon abundance in density fractions decreased in the order of light>heavy>occluded, highlighting the importance of both surface sorption and aggregation to the preservation of organics. Radiocarbon abundance was correlated with pH, with variance also grouping by dominate vegetation type. Soil order was also identified as an important proxy variable for C and radiocarbon abundance. Preliminary results suggest that both integrative proxies as well as physicochemical properties may be needed to account for variation in soil C abundance and stability at the continental scale.

Constituent attachment and voluntary turnover in low-wage/low-skill service work.

PubMed

Ellingson, Jill E; Tews, Michael J; Dachner, Alison M

2016-01-01

This paper draws on life stage theory, ethnographic research conducted in the service sector, and evidence for secondary segmentation within the low-wage/low-skill labor force to offer evidence that social bond development with coworkers can help reduce the high rate of turnover observed in low-wage/low-skill service work. Contrary to the belief that these employees will leave before social ties can develop, constituent attachment was found to be the only significant predictor of turnover in 2 samples of front-line service workers in a casual dining, national restaurant chain after controlling for other aspects of work that can create a sense of attachment to a job, and other job attitudes, such as satisfaction and commitment. However, the effect was dependent on developmental life stage. Constituent attachment reduced turnover among workers classified as emerging adults, whereas constituent attachment did little to affect turnover among nonemerging adults. Implications of the results are discussed with respect to the value of considering segmentation in future research on turnover in the service sector and the use of life stage theory for understanding the leaving behavior of workers in different stages of adulthood. (c) 2016 APA, all rights reserved).

Impairment of autophagy by TTR V30M aggregates: in vivo reversal by TUDCA and curcumin.

PubMed

Teixeira, Cristina A; Almeida, Maria do Rosário; Saraiva, Maria João

2016-09-01

Transthyretin (TTR)-related amyloidoses are diseases characterized by extracellular deposition of amyloid fibrils and aggregates in tissues composed of insoluble misfolded TTR that becomes toxic. Previous studies have demonstrated the ability of small compounds in preventing and reversing TTR V30M deposition in transgenic mice gastrointestinal (GI) tract as well as lowering biomarkers associated with cellular stress and apoptotic mechanisms. In the present study we aimed to study TTR V30M aggregates effect in autophagy, a cellular mechanism crucial for cell survival that has been implicated in the development of several neurodegenerative diseases. We were able to demonstrate in cell culture that TTR V30M aggregates cause a partial impairment of the autophagic machinery as shown by p62 accumulation, whereas early steps of the autophagic flux remain unaffected as shown by autophagosome number evaluation and LC3 turnover assay. Our studies performed in TTR V30M transgenic animals demonstrated that tauroursodeoxycholic acid (TUDCA) and curcumin effectively reverse p62 accumulation in the GI tract pointing to the ability of both compounds to modulate autophagy additionally to mitigate apoptosis. Overall, our in vitro and in vivo studies establish an association between TTR V30M aggregates and autophagy impairment and suggest the use of autophagy modulators as an additional and alternative therapeutic approach for the treatment of TTR V30M-related amyloidosis. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

Sediment composition for the assessment of water erosion and nonpoint source pollution in natural and fire-affected landscapes.

PubMed

Carkovic, Athena B; Pastén, Pablo A; Bonilla, Carlos A

2015-04-15

Water erosion is a leading cause of soil degradation and a major nonpoint source pollution problem. Many efforts have been undertaken to estimate the amount and size distribution of the sediment leaving the field. Multi-size class water erosion models subdivide eroded soil into different sizes and estimate the aggregate's composition based on empirical equations derived from agricultural soils. The objective of this study was to evaluate these equations on soil samples collected from natural landscapes (uncultivated) and fire-affected soils. Chemical, physical, and soil fractions and aggregate composition analyses were performed on samples collected in the Chilean Patagonia and later compared with the equations' estimates. The results showed that the empirical equations were not suitable for predicting the sediment fractions. Fine particles, including primary clay, primary silt, and small aggregates (<53 μm) were over-estimated, and large aggregates (>53 μm) and primary sand were under-estimated. The uncultivated and fire-affected soils showed a reduced fraction of fine particles in the sediment, as clay and silt were mostly in the form of large aggregates. Thus, a new set of equations was developed for these soils, where small aggregates were defined as particles with sizes between 53 μm and 250 μm and large aggregates as particles>250 μm. With r(2) values between 0.47 and 0.98, the new equations provided better estimates for primary sand and large aggregates. The aggregate's composition was also well predicted, especially the silt and clay fractions in the large aggregates from uncultivated soils (r(2)=0.63 and 0.83, respectively) and the fractions of silt in the small aggregates (r(2)=0.84) and clay in the large aggregates (r(2)=0.78) from fire-affected soils. Overall, these new equations proved to be better predictors for the sediment and aggregate's composition in uncultivated and fire-affected soils, and they reduce the error when estimating soil loss in natural landscapes. Copyright © 2015 Elsevier B.V. All rights reserved.

Soil process modelling in CZO research: gains in data harmonisation and model validation

NASA Astrophysics Data System (ADS)

van Gaans, Pauline; Andrianaki, Maria; Kobierska, Florian; Kram, Pavel; Lamacova, Anna; Lair, Georg; Nikolaidis, Nikos; Duffy, Chris; Regelink, Inge; van Leeuwen, Jeroen P.; de Ruiter, Peter

2014-05-01

Various soil process models were applied to four European Critical Zone observatories (CZOs), the core research sites of the FP7 project SoilTrEC: the Damma glacier forefield (CH), a set of three forested catchments on geochemically contrasing bedrocks in the Slavkov Forest (CZ), a chronosequence of soils in the former floodplain of the Danube of Fuchsenbigl/Marchfeld (AT), and the Koiliaris catchments in the north-western part of Crete, (GR). The aim of the modelling exercises was to apply and test soil process models with data from the CZOs for calibration/validation, identify potential limits to the application scope of the models, interpret soil state and soil functions at key stages of the soil life cycle, represented by the four SoilTrEC CZOs, contribute towards harmonisation of data and data acquisition. The models identified as specifically relevant were: The Penn State Integrated Hydrologic Model (PIHM), a fully coupled, multiprocess, multi-scale hydrologic model, to get a better understanding of water flow and pathways, The Soil and Water Assessment Tool (SWAT), a deterministic, continuous time (daily time step) basin scale model, to evaluate the impact of soil management practices, The Rothamsted Carbon model (Roth-C) to simulate organic carbon turnover and the Carbon, Aggregation, and Structure Turnover (CAST) model to include the role of soil aggregates in carbon dynamics, The Ligand Charge Distribution (LCD) model, to understand the interaction between organic matter and oxide surfaces in soil aggregate formation, and The Terrestrial Ecology Model (TEM) to obtain insight into the link between foodweb structure and carbon and nutrient turnover. With some exceptions all models were applied to all four CZOs. The need for specific model input contributed largely to data harmonisation. The comparisons between the CZOs turned out to be of great value for understanding the strength and limitations of the models, as well as the differences in soil conditions between the CZOs. The CZO modelling led to further developments of the PIHM, with incorporation of functionality for karstic fracture flow (Koiliaris) and fracture flow anisotropy (Damma). The Damma case also provided experience on how to use results from geophysical investigations in model refinement. The SWAT modelling showed variability among the CZOs in hydraulic conductivity, the curve number that determines how fast rainfall results in runoff, and soil moisture capacity. Roth-C and CAST showed carbon sequestration fluxes to be low for old cultivated soils (Koiliaris) and high for new soils (Damma), where the latter site also had very high turnover rates. The LCD modelling, so far limited to the calcareous floodplain soils in Austria, explains differences in C-sequestration capacity between forest and agricultural soils from competition between phosphate and soil organic matter for adsorption sites on Fe-(hydr)oxides. The wide variety of soil (eco)system conditions challenged the TEM model and showed important directions for refinement: 1) differentiating between various fractions of organic matter and concomitant microbial decomposition pathways, and 2) the need to better define the physiological traits of the organisms in relation to local environmental conditions.

Initial turnover rates of two standard wood substrates following land-use change in subalpine ecosystems in the Swiss Alps

Treesearch

Anita C. Risch; Martin F. Jurgensen; Deborah S. Page-Dumroese; Martin Schutz

2013-01-01

Forest cover has increased in mountainous areas of Europe over the past decades because of the abandonment of agricultural areas (land-use change). For this reason, understanding how land-use change affects carbon (C) source-sink strength is of great importance. However, most studies have assessed mountainous systems C stocks, and less is known about C turnover rates,...

Stability of Soil Carbon Fractions - from molecules to aggregates

NASA Astrophysics Data System (ADS)

Mueller, C. W.; Mueller, K. E.; Freeman, K. H.; Eissenstat, D.; Kögel-Knabner, I.

2009-12-01

The turnover of soil organic matter (SOM) is controlled both by its chemical composition, its spatial bioavailability and the association with the mineral phase. Separation by physical fractionation of bulk soils and subsequent chemical analysis of these fractions should give insights to how compositional differences in SOM drive turnover rates of different size-defined carbon pools. The main objective of the study was to elucidate the relative abundance and recalcitrance of lignin and plant lipids (e.g. cutin and suberin) in the course of SOM decomposition within aggregated bulk soils and SOM fractions. By the parallel incubation of physically-separated size fractions and bulk soils of the Ah horizon from a forested soil (Picea abies L.Karst) over a period of 400 days, a unique set of samples was created to study SOM dynamics. We used solid-state 13C-CPMAS NMR spectroscopy and GC-MS (after copper oxide oxidation and solvent extraction) to analyze the composition of the incubated samples. The abundance and isotopic composition (including 13C and 14C) of respired CO2 further enabled us to monitor the dynamics of SOM mineralization. This approach allowed for differentiating between C stabilization of soil fractions due to accessibility/aggregation and to recalcitrance at different scales of resolution (GC-MS, NMR). A relative enrichment of alkyl C and decreasing lignin contents in the order of sand < silt < clay were observed by 13C-NMR and GC-MS within soils and fractions before the incubation, resulting in increased lipid to lignin ratios with decreasing particle size. A relative enrichment of lignin in the incubated fractions compared to the incubated bulk soils clearly indicated the preferential mineralization of less recalcitrant C compounds that were spatially inaccessible in aggregates of the bulk soil. Differences in the abundance of various lignin, cutin, and suberin monomers measured by GC-MS before and after the incubation indicate selective degradation and preservation patterns at the molecular scale that are rarely observed and are unresolved by NMR analyses. We suggest that the monomer-specific patterns of lignin, cutin, and suberin decomposition facilitate better understanding and modelling of SOM dynamics by providing a tool to potentially separate the influence of input rates from selective preservation on the abundance of these bipolymers in soil.

Home nurses' turnover intentions: the impact of informal supervisory feedback and self-efficacy.

PubMed

Van Waeyenberg, Thomas; Decramer, Adelien; Anseel, Frederik

2015-12-01

To examine how home nurses' turnover intentions are affected by the quality and frequency of supervisory feedback and by their own self-efficacy. Little is known about effective retention strategies for the growing home healthcare sector that struggles to retain an adequate workforce. While the work environment and supervisors have been found to play a key-role in nurses' turnover intentions, home nurses mostly work autonomously and apart from their supervisors. These circumstances require a customized approach and need to be understood to ensure high-quality home health care. We used a correlational, cross-sectional survey design. A convenience sample of 312 home nurses was selected from a division of a large home health care organization in Flanders, Belgium. Data were collected in 2013 using structured questionnaires and analysed using descriptive statistics, structural equation modelling and relative weight analysis. The quality of feedback was related to lower levels of turnover intentions. This relationship was fully mediated by home nurses' self-efficacy. Frequent favourable feedback was directly related to lower turnover intentions while the relationship between frequent unfavourable feedback and turnover intentions was conditional on home nurses' level of self-efficacy. This study contributes to our understanding of home nurses' turnover intentions and the role of informal supervisory feedback and home nurses' self-efficacy. © 2015 John Wiley & Sons Ltd.

Job embeddedness factors as a predictor of turnover intention among infection control nurses in Korea.

PubMed

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.

Enhanced Catalytic Activity and Unexpected Products from the Oxidation of Cyclohexene by Organic Nanoparticles of 5,10,15,20-Tetrakis-(2,3,4,5,6-pentafluorophenyl)porphyrinatoiron(III) in Water by Using O2

PubMed Central

Smeureanu, Gabriela; Aggarwal, Amit; Soll, Clifford E.; Arijeloye, Julius; Malave, Erik

2010-01-01

The catalytic oxidation of alkenes by most iron porphyrins using a variety of oxygen sources, but generally not dioxygen, yields the epoxide with minor quantities of other products. The turnover numbers for these catalysts are modest, ranging from a few hundred to a few thousand depending on the porphyrin structure, axial ligands, and other reaction conditions. Halogenation of substituents increases the activity of the metalloporphyrin catalyst and/or makes it more robust to oxidative degradation. Oxidation of cyclohexene by 5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)porphyrinato iron(III), ([FeIII(tppf20)]) and H2O2 is typical of the latter: the epoxide is 99% of the product and turnover numbers are about 350.[1–4] Herein, we report that dynamic organic nanoparticles (ONPs) of [FeIII(tppf20)] with a diameter of 10 nm, formed by host–guest solvent methods, catalytically oxidize cyclohexene with O2 to yield only 2-cyclohexene-1-one and 2-cyclohexene-1-ol with approximately 10-fold greater turnover numbers compared to the non-aggregated metalloporphyrin in acetonitrile/methanol. These ONPs facilitate a greener reaction because the reaction solvent is 89% water and O2 is the oxidant in place of synthetic oxygen sources. This reactivity is unexpected because the metalloporphyrins are in close proximity and oxidative degradation of the catalyst should be enhanced, thus causing a significant decrease in catalytic turnovers. The allylic products suggest a different oxidative mechanism compared to that of the solvated metalloporphyrins. These results illustrate the unique properties of some ONPs relative to the component molecules or those attached to supports. PMID:19777510

The impact of turnover among respiratory care practitioners in a health care system: frequency and associated costs.

PubMed

Stoller, J K; Orens, D K; Kester, L

2001-03-01

Retention of respiratory therapists (RTs) is a desired institutional goal that reflects department loyalty and RTs' satisfaction. When RTs leave a department, services are disrupted and new therapists must undergo orientation and training, which requires time and expense. Despite the widely shared goal of minimal turnover, neither the annual rate nor the associated expense of turnover for RTs has been described. Determine the rate of RT turnover and the costs related to training new staff members. The Cleveland Clinic Health System is composed of 9 participating hospitals, which range from small, community-based institutions to large, tertiary care institutions. To elicit information about annual turnover among RTs throughout the system, we conducted a survey of key personnel in each of the hospitals' respiratory therapy departments. To calculate the costs of training, we reviewed the training schedule for an RT joining the Respiratory Therapy Section at the Cleveland Clinic Hospital. Cost estimates reflect the duration of training by various supervisory RTs, their respective wages (including benefit costs), and educational materials used in training and orientation. Turnover rates ranged from 3% to 18% per year. Five of the 8 institutions from which rates were available reported rates greater than 8% per year. The rate of annual turnover correlated significantly with the ratio of hospital beds to RT staff (Pearson r = 0.784, r(2) = 0.61, p = 0.02). The cost of training an RT at the Cleveland Clinic Hospital totaled $3,447.11. Turnover among respiratory therapists poses a substantial problem because of its frequency and expense. Greater attention to issues affecting turnover and to enhancing retention of RTs is warranted.

Rest break organization in geriatric care and turnover: a multimethod cross-sectional study.

PubMed

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.

Job satisfaction and turnover intent among hospital social workers in the United States.

PubMed

Pugh, Greg L

2016-08-01

Feelings of job satisfaction and turnover intentions among social workers affect work quality for both social workers and the people for whom they provide services. Existing literature on job satisfaction among hospital social workers is limited, and is overly focused on issues of compensation. There is job satisfaction research with hospital nurses available for comparison. Other informative social work research on job satisfaction and turnover exists in mental health and generally, across settings. Research on turnover intent in social work is primarily from child welfare settings and may not generalize. The literature notes gaps and contradictions about predictors of job satisfaction and turnover intent. Using a large national dataset of hospital social workers, this research clarifies and fills gaps regarding hospital social workers, and explores how Herzberg's theory of work can clarify the difference between sources of job dissatisfaction and job satisfaction. Findings include hospital social workers reporting high job satisfaction and that demographics do not contribute to the predictive models. The findings do support centralized social work departments and variety in the job functions of hospital social workers, and are consistent with the theoretical framework.

Robustness of the Process of Nucleoid Exclusion of Protein Aggregates in Escherichia coli

PubMed Central

Neeli-Venkata, Ramakanth; Martikainen, Antti; Gupta, Abhishekh; Gonçalves, Nadia; Fonseca, Jose

2016-01-01

ABSTRACT Escherichia coli segregates protein aggregates to the poles by nucleoid exclusion. Combined with cell divisions, this generates heterogeneous aggregate distributions in subsequent cell generations. We studied the robustness of this process with differing medium richness and antibiotics stress, which affect nucleoid size, using multimodal, time-lapse microscopy of live cells expressing both a fluorescently tagged chaperone (IbpA), which identifies in vivo the location of aggregates, and HupA-mCherry, a fluorescent variant of a nucleoid-associated protein. We find that the relative sizes of the nucleoid's major and minor axes change widely, in a positively correlated fashion, with medium richness and antibiotic stress. The aggregate's distribution along the major cell axis also changes between conditions and in agreement with the nucleoid exclusion phenomenon. Consequently, the fraction of aggregates at the midcell region prior to cell division differs between conditions, which will affect the degree of asymmetries in the partitioning of aggregates between cells of future generations. Finally, from the location of the peak of anisotropy in the aggregate displacement distribution, the nucleoid relative size, and the spatiotemporal aggregate distribution, we find that the exclusion of detectable aggregates from midcell is most pronounced in cells with mid-sized nucleoids, which are most common under optimal conditions. We conclude that the aggregate management mechanisms of E. coli are significantly robust but are not immune to stresses due to the tangible effect that these have on nucleoid size. IMPORTANCE Escherichia coli segregates protein aggregates to the poles by nucleoid exclusion. From live single-cell microscopy studies of the robustness of this process to various stresses known to affect nucleoid size, we find that nucleoid size and aggregate preferential locations change concordantly between conditions. Also, the degree of influence of the nucleoid on aggregate positioning differs between conditions, causing aggregate numbers at midcell to differ in cell division events, which will affect the degree of asymmetries in the partitioning of aggregates between cells of future generations. Finally, we find that aggregate segregation to the cell poles is most pronounced in cells with mid-sized nucleoids. We conclude that the energy-free process of the midcell exclusion of aggregates partially loses effectiveness under stressful conditions. PMID:26728194

Loss of job-related right to healthcare associated with employment turnover: challenges for the Mexican health system.

PubMed

Guerra, Germán; Gutiérrez-Calderón, Emilio; Salgado de Snyder, Nelly; Borja-Aburto, Víctor Hugo; Martínez-Valle, Adolfo; González-Block, Miguel Ángel

2018-06-15

The Mexican health system segments access and right to healthcare according to worker position in the labour market. In this contribution we analyse how access and continuity of healthcare gets interrupted by employment turnover in the labour market, including its formal and informal sectors, as experienced by affiliates to the Mexican Institute of Social Security (IMSS) at national level, and of workers with type 2 diabetes (T2DM) in Mexico City. Using data from the National Employment and Occupation Survey, 2014, and from IMSS electronic medical records for workers in Mexico City, we estimated annual employment turnover rates to measure the loss of healthcare access due to labour market dynamics. We fitted a binary logistic regression model to analyse the association between sociodemographic variables and employment turnover. Lastly we analysed job-related access to health care in relation to employment turnover events. At national level, 38.3% of IMSS affiliates experienced employment turnover at least once, thus losing the right to access to healthcare. The turnover rate for T2DM patients was 22.5%. Employment turnover was more frequent at ages 20-39 (38.6% national level; 28% T2DM) and among the elderly (62.4% national level; 26% T2DM). At the national level, higher educational levels (upper-middle, OR = 0.761; upper, OR = 0.835) and income (5 minimum wages or more, OR = 0.726) were associated with lower turnover. Being single and younger were associated with higher turnover (OR = 1.413). T2DM patients aged 40-59 (OR = 0.655) and with 5 minimum wages or more (OR = 0.401) experienced less turnover. Being a T2DM male patient increased the risk of experiencing turnover (OR = 1.166). Up to 89% of workers losing IMSS affiliation and moving on to other jobs failed to gain job-related access to health services. Only 9% gained access to the federal workers social security institute (ISSSTE). Turnover across labour market sectors is frequently experienced by the workforce in Mexico, worsening among the elderly and the young, and affecting patients with chronic diseases. This situation needs to be prospectively addressed by health system policies that aim to expand the financial health protection during an employment turnover event.

Disruption of key NADH-binding pocket residues of the Mycobacterium tuberculosis InhA affects DD-CoA binding ability.

PubMed

Shaw, Daniel J; Robb, Kirsty; Vetter, Beatrice V; Tong, Madeline; Molle, Virginie; Hunt, Neil T; Hoskisson, Paul A

2017-07-05

Tuberculosis (TB) is a global health problem that affects over 10 million people. There is an urgent need to develop novel antimicrobial therapies to combat TB. To achieve this, a thorough understanding of key validated drug targets is required. The enoyl reductase InhA, responsible for synthesis of essential mycolic acids in the mycobacterial cell wall, is the target for the frontline anti-TB drug isoniazid. To better understand the activity of this protein a series of mutants, targeted to the NADH co-factor binding pocket were created. Residues P193 and W222 comprise a series of hydrophobic residues surrounding the cofactor binding site and mutation of both residues negatively affect InhA function. Construction of an M155A mutant of InhA results in increased affinity for NADH and DD-CoA turnover but with a reduction in V max for DD-CoA, impairing overall activity. This suggests that NADH-binding geometry of InhA likely permits long-range interactions between residues in the NADH-binding pocket to facilitate substrate turnover in the DD-CoA binding region of the protein. Understanding the precise details of substrate binding and turnover in InhA and how this may affect protein-protein interactions may facilitate the development of improved inhibitors enabling the development of novel anti-TB drugs.

Improving certified nurse aide retention. A long-term care management challenge.

PubMed

Mesirow, K M; Klopp, A; Olson, L L

1998-03-01

In the long-term care industry, the turnover rate among nurse aides is extremely high. This adversely affects resident satisfaction, resident care, morale, and finances. It presents a challenge to long-term care administration. Refusing to accept high turnover as an impossible situation allows changes to be made. The authors describe how the staff at one intermediate care facility identified its problems, assessed the causes, and implemented corrective action.

Effects of long- and short-term management on the functional structure of meadows through species turnover and intraspecific trait variability.

PubMed

Volf, Martin; Redmond, Conor; Albert, Ágnes J; Le Bagousse-Pinguet, Yoann; Biella, Paolo; Götzenberger, Lars; Hrázský, Záboj; Janeček, Štěpán; Klimešová, Jitka; Lepš, Jan; Šebelíková, Lenka; Vlasatá, Tereza; de Bello, Francesco

2016-04-01

The functional structures of communities respond to environmental changes by both species replacement (turnover) and within-species variation (intraspecific trait variability; ITV). Evidence is lacking on the relative importance of these two components, particularly in response to both short- and long-term environmental disturbance. We hypothesized that such short- and long-term perturbations would induce changes in community functional structure primarily via ITV and turnover, respectively. To test this we applied an experimental design across long-term mown and abandoned meadows, with each plot containing a further level of short-term management treatments: mowing, grazing and abandonment. Within each plot, species composition and trait values [height, shoot biomass, and specific leaf area (SLA)] were recorded on up to five individuals per species. Positive covariations between the contribution of species turnover and ITV occurred for height and shoot biomass in response to both short- and long-term management, indicating that species turnover and intraspecific adjustments selected for similar trait values. Positive covariations also occurred for SLA, but only in response to long-term management. The contributions of turnover and ITV changed depending on both the trait and management trajectory. As expected, communities responded to short-term disturbances mostly through changes in intraspecific trait variability, particularly for height and biomass. Interestingly, for SLA they responded to long-term disturbances by both species turnover and intraspecific adjustments. These findings highlight the importance of both ITV and species turnover in adjusting grassland functional trait response to environmental perturbation, and show that the response is trait specific and affected by disturbance regime history.

Post-absorptive muscle protein turnover affects resistance training hypertrophy

PubMed Central

Reidy, Paul T.; Borack, Michael S.; Markofski, Melissa M.; Dickinson, Jared M.; Fry, Christopher S.; Deer, Rachel R.; Volpi, Elena; Rasmussen, Blake B.

2017-01-01

Purpose Acute bouts of resistance exercise and subsequent training alters protein turnover in skeletal muscle. The mechanisms responsible for the changes in basal post-absorptive protein turnover and its impact on muscle hypertrophy following resistance exercise training are unknown. To determine whether post-absorptive muscle protein turnover following 12 weeks of resistance exercise training (RET) plays a role in muscle hypertrophy. In addition, we were interested in determining potential molecular mechanisms responsible for altering post-training muscle protein turnover. Methods Healthy young men (n=31) participated in supervised whole body progressive RET at 60-80% 1 repetition maximum (1-RM), 3d/wk for 3 months. Pre- and post-training vastus lateralis muscle biopsies and blood samples taken during an infusion of 13C6 and 15N phenylalanine and were used to assess skeletal muscle protein turnover in the post-absorptive state. Lean body mass (LBM), muscle strength (determined by dynamometry), vastus lateralis muscle thickness (MT), myofiber type-specific cross-sectional area (CSA), and mRNA were assessed pre- and post-RET. Results RET increased strength (12-40%), LBM (∼5%), MT (∼15%) and myofiber CSA (∼20%) (p<0.05). Muscle protein synthesis (MPS) increased 24% while muscle protein breakdown (MPB) decreased 21% respectively. These changes in protein turnover resulted in an improved net muscle protein balance in the basal state following RET. Further, the change in basal MPS is positively associated (r=0.555, p=0.003) with the change in muscle thickness. Conclusion Post-absorptive muscle protein turnover is associated with muscle hypertrophy during resistance exercise training. PMID:28280974

Long-term nitrogen addition affects the phylogenetic turnover of soil microbial community responding to moisture pulse

DOE PAGES

Liu, Chi; Yao, Minjie; Stegen, James C.; ...

2017-12-13

How press disturbance (long-term) influences the phylogenetic turnover of soil microbial communities responding to pulse disturbances (short-term) is not fully known. Understanding the complex connections between the history of environmental conditions, assembly processes and microbial community dynamics is necessary to predict microbial response to perturbation. Here, we started by investigating phylogenetic spatial turnover (based on DNA) of soil prokaryotic communities after long-term nitrogen (N) deposition and temporal turnover (based on RNA) of communities responding to pulse by conducting short-term rewetting experiments. The results showed that moderate N addition increased ecological stochasticity and phylogenetic diversity. In contrast, high N addition slightlymore » increased homogeneous selection and decreased phylogenetic diversity. Examining the system with higher phylogenetic resolution revealed a moderate contribution of variable selection across the whole N gradient. The moisture pulse experiment showed that high N soils had higher rates of phylogenetic turnover across short phylogenetic distances and significant changes in community compositions through time. Long-term N input history influenced spatial turnover of microbial communities, but the dominant community assembly mechanisms differed across different N deposition gradients. We further revealed an interaction between press and pulse disturbances whereby deterministic processes were particularly important following pulse disturbances in high N soils.« less

Long-term nitrogen addition affects the phylogenetic turnover of soil microbial community responding to moisture pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chi; Yao, Minjie; Stegen, James C.

How press disturbance (long-term) influences the phylogenetic turnover of soil microbial communities responding to pulse disturbances (short-term) is not fully known. Understanding the complex connections between the history of environmental conditions, assembly processes and microbial community dynamics is necessary to predict microbial response to perturbation. Here, we started by investigating phylogenetic spatial turnover (based on DNA) of soil prokaryotic communities after long-term nitrogen (N) deposition and temporal turnover (based on RNA) of communities responding to pulse by conducting short-term rewetting experiments. The results showed that moderate N addition increased ecological stochasticity and phylogenetic diversity. In contrast, high N addition slightlymore » increased homogeneous selection and decreased phylogenetic diversity. Examining the system with higher phylogenetic resolution revealed a moderate contribution of variable selection across the whole N gradient. The moisture pulse experiment showed that high N soils had higher rates of phylogenetic turnover across short phylogenetic distances and significant changes in community compositions through time. Long-term N input history influenced spatial turnover of microbial communities, but the dominant community assembly mechanisms differed across different N deposition gradients. We further revealed an interaction between press and pulse disturbances whereby deterministic processes were particularly important following pulse disturbances in high N soils.« less

[The effect of assertiveness training on communication related factors and personnel turnover rate among hospital nurses].

PubMed

Kang, Myung Ja; Lee, Haejung

2006-08-01

The purpose of this study was to investigate the effects of assertiveness training on nurses' assertive behaviors, interpersonal relations, communication conflicts, conflict management style and personnel turnover rate. A non-equivalent control group pretest-posttest design was used in this study. Nurses were assigned into the experimental or control groups, each consisting of 39 nurses. Data was collected between January to March 2004. An 'Assertiveness Training Program' for Nurses developed by Park was used for the study. To emphasize assertiveness practice, 5 practice sessions utilizing ABCDE principles were added to Park's program. To examine the effects of the program, differences between the two groups in assertive behaviors, interpersonal relations, communication conflicts, conflict management style and personnel turnover rate were analyzed using ANCOVA. The assertiveness training was effective in improving the nurses' assertiveness behaviors, but was not effective in improving interpersonal relations, reducing the subjects' communication conflicts, changing the conflict management style or reducing their personnel turnover rate. There have been many studies about factors affecting nurses' personnel turnover rates, but few have been done about methods of intervention to reduce the personnel turnover rate. Thus, this study provides a significant contribution in attempting such an intervention from nursing management perspectives.

Long-term nitrogen addition affects the phylogenetic turnover of soil microbial community responding to moisture pulse.

PubMed

Liu, Chi; Yao, Minjie; Stegen, James C; Rui, Junpeng; Li, Jiabao; Li, Xiangzhen

2017-12-13

How press disturbance (long-term) influences the phylogenetic turnover of soil microbial communities responding to pulse disturbances (short-term) is not fully known. Understanding the complex connections between the history of environmental conditions, assembly processes and microbial community dynamics is necessary to predict microbial response to perturbation. We started by investigating phylogenetic spatial turnover (based on DNA) of soil prokaryotic communities after long-term nitrogen (N) deposition and temporal turnover (based on RNA) of communities responding to pulse by conducting short-term rewetting experiments. The results showed that moderate N addition increased ecological stochasticity and phylogenetic diversity. In contrast, high N addition slightly increased homogeneous selection and decreased phylogenetic diversity. Examining the system with higher phylogenetic resolution revealed a moderate contribution of variable selection across the whole N gradient. The moisture pulse experiment showed that high N soils had higher rates of phylogenetic turnover across short phylogenetic distances and significant changes in community compositions through time. Long-term N input history influenced spatial turnover of microbial communities, but the dominant community assembly mechanisms differed across different N deposition gradients. We further revealed an interaction between press and pulse disturbances whereby deterministic processes were particularly important following pulse disturbances in high N soils.

Is the effect of person-organisation fit on turnover intention mediated by job satisfaction? A survey of community health workers in China

PubMed Central

Yan, Fei; Wang, Wei; Li, Guohong

2017-01-01

Objectives Person-organisation fit (P-O fit) is a predictor of work attitude. However, in the area of human resource for health, the literature of P-O fit is quite limited. It is unclear whether P-O fit directly or indirectly affects turnover intention. This study aims to examine the mediation effect of job satisfaction on the relationship between P-O fit and turnover intention based on data from China. Design and methods This is a cross-sectional survey of community health workers (CHWs) in China in 2013. A questionnaire of P-O fit, job satisfaction and turnover intention was developed, and its validity and reliability were assessed. Multiple regression and structural equation modelling were used to examine the relationship among P-O fit, job satisfaction and turnover intention. Setting and participants Multistage sampling was applied. In total, 656 valid questionnaire responses were collected from CHWs in four provincial regions in China, namely Shanghai, Shaanxi, Shandong and Anhui. Results P-O fit was directly related to job satisfaction (standardised β 0.246) and inversely related to turnover intention (standardised β −0.186). In the mediation model, the total effect of P-O fit on turnover intention was −0.186 (p<0.001); the direct effect of P-O fit on turnover intention was −0.094 (p<0.01); the indirect effect of job satisfaction on the relationship between P-O fit and turnover intention was −0.092 (p<0.001). Conclusions The effect of P-O fit on turnover intention was partially mediated through job satisfaction. It is suggested that more work attitude variables and different dimensions of P-O fit be taken into account to examine the complete mechanism of person-organisation interaction. Indirect measures of P-O fit should be encouraged in practice to enhance work attitudes of health workers. PMID:28399513

On the Origin of the High Column Density Turnover in the HI Column Density Distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

We study the high column density regime of the HI column density distribution function and argue that there are two distinct features: a turnover at NHI ~ 10^21 cm^-2 which is present at both z=0 and z ~ 3, and a lack of systems above NHI ~ 10^22 cm^-2 at z=0. Using observations of the column density distribution, we argue that the HI-H2 transition does not cause the turnover at NHI ~ 10^21 cm^-2, but can plausibly explain the turnover at NHI > 10^22 cm^-2. We compute the HI column density distribution of individual galaxies in the THINGS sample andmore » show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the HI map or to averaging in radial shells. Our results indicate that the similarity of HI column density distributions at z=3 and z=0 is due to the similarity of the maximum HI surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within GMCs cannot affect the DLA column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ~ kpc scales with those estimated from quasar spectra which probe sub-pc scales due to the steep power spectrum of HI column density fluctuations observed in nearby galaxies.« less

A rationale for cognitively-based resilience and psychological first aid (PFA) training: a structural modeling analysis.

PubMed

Everly, George S; Smith, Kenneth J; Lating, Jeffrey M

2009-01-01

Based on the recommendations of Rodgers (2010) and practices by Smith, Davy, & Everly (2007) and Everly, Smith, and Welzant (2008), structural modeling was used in this investigation designed to better discern causal mechanisms within the cognitive-affective arousal construct that contribute to burnout, job dissatisfaction, turnover intention, and performance. The primary purpose of this study was to better inform those interested in program develop and clinical intervention of the nature of mechanisms of pathogenesis and resiliency. This study utilized the responses of the 491 individuals employed in public accounting. Results indicate that the cognitive-affective domain is an essential determinant of burnout, job dissatisfaction, turnover intention, and performance. Furthermore, cognitive states appear to exert their effect through affective arousal that subsequently appears to have a defining role in the development of the aforementioned variables.

Implementation and Evaluation of Self-Scheduling in a Hospital System.

PubMed

Wright, Christina; McCartt, Peggy; Raines, Diane; Oermann, Marilyn H

Inflexible work schedules affect job satisfaction and influence nurse turnover. Job satisfaction is a significant predictor of nurse retention. Acute care hospitals report that job satisfaction is influenced by autonomy and educational opportunity. This project discusses implementation of computer-based self-scheduling in a hospital system and its impact. It is important for staff development educators to be aware that self-scheduling may play a key role in autonomy, professional development, turnover, and hospital costs.

Characterization of the Xylella fastidiosa PD1671 Gene Encoding Degenerate c-di-GMP GGDEF/EAL Domains, and Its Role in the Development of Pierce’s Disease

PubMed Central

Cursino, Luciana; Athinuwat, Dusit; Patel, Kelly R.; Galvani, Cheryl D.; Zaini, Paulo A.; Li, Yaxin; De La Fuente, Leonardo; Hoch, Harvey C.; Burr, Thomas J.; Mowery, Patricia

2015-01-01

Xylella fastidiosa is an important phytopathogenic bacterium that causes many serious plant diseases including Pierce’s disease of grapevines. X. fastidiosa is thought to induce disease by colonizing and clogging xylem vessels through the formation of cell aggregates and bacterial biofilms. Here we examine the role in X. fastidiosa virulence of an uncharacterized gene, PD1671, annotated as a two-component response regulator with potential GGDEF and EAL domains. GGDEF domains are found in c-di-GMP diguanylate cyclases while EAL domains are found in phosphodiesterases, and these domains are for c-di-GMP production and turnover, respectively. Functional analysis of the PD1671 gene revealed that it affected multiple X. fastidiosa virulence-related phenotypes. A Tn5 PD1671 mutant had a hypervirulent phenotype in grapevines presumably due to enhanced expression of gum genes leading to increased exopolysaccharide levels that resulted in elevated biofilm formation. Interestingly, the PD1671 mutant also had decreased motility in vitro but did not show a reduced distribution in grapevines following inoculation. Given these responses, the putative PD1671 protein may be a negative regulator of X. fastidiosa virulence. PMID:25811864

Characterization of the Xylella fastidiosa PD1671 gene encoding degenerate c-di-GMP GGDEF/EAL domains, and its role in the development of Pierce's disease.

PubMed

Cursino, Luciana; Athinuwat, Dusit; Patel, Kelly R; Galvani, Cheryl D; Zaini, Paulo A; Li, Yaxin; De La Fuente, Leonardo; Hoch, Harvey C; Burr, Thomas J; Mowery, Patricia

2015-01-01

Xylella fastidiosa is an important phytopathogenic bacterium that causes many serious plant diseases including Pierce's disease of grapevines. X. fastidiosa is thought to induce disease by colonizing and clogging xylem vessels through the formation of cell aggregates and bacterial biofilms. Here we examine the role in X. fastidiosa virulence of an uncharacterized gene, PD1671, annotated as a two-component response regulator with potential GGDEF and EAL domains. GGDEF domains are found in c-di-GMP diguanylate cyclases while EAL domains are found in phosphodiesterases, and these domains are for c-di-GMP production and turnover, respectively. Functional analysis of the PD1671 gene revealed that it affected multiple X. fastidiosa virulence-related phenotypes. A Tn5 PD1671 mutant had a hypervirulent phenotype in grapevines presumably due to enhanced expression of gum genes leading to increased exopolysaccharide levels that resulted in elevated biofilm formation. Interestingly, the PD1671 mutant also had decreased motility in vitro but did not show a reduced distribution in grapevines following inoculation. Given these responses, the putative PD1671 protein may be a negative regulator of X. fastidiosa virulence.

Impact of bone turnover markers and/or educational information on persistence to oral bisphosphonate therapy: a community setting-based trial.

PubMed

Silverman, S L; Nasser, K; Nattrass, S; Drinkwater, B

2012-03-01

We examined how the use of bone turnover markers and educational information affects persistence of bisphosphonate use in osteoporotic patients. We found that reporting bone turnover results and/or educational information did not affect persistence. Long-term adherence and persistence to osteoporosis medication are poor. We examined whether reporting of bone turnover marker results, education about osteoporosis, or a combination of both would increase persistence to oral bisphosphonates. Two hundred and forty women who were 5 years postmenopausal with BMD at least 2.0 standard deviations below normal were recruited for the study. All women were given a new prescription for alendronate and randomly assigned to one of four groups: (1) bone marker results at baseline, 3 and 12 months; (2) educational materials every month and a membership in the National Osteoporosis Foundation; (3) bone marker and educational information; and (4) control, no information other than usual care. Persistence among randomization groups was tested using survival analysis adjusting for the delay between intervention methods. Of those filling their initial prescription, 95.5% refilled their prescription at the end of the first month, 87% at 3 months, 82% at 6 months, and 78% at 10 months. Overall persistence through 12 months was 54%. There was no difference found among the four groups for persistence time using (p > 0.58). Providing bone turnover marker results is not an effective way to enhance early compliance and persistence with drug therapy. While the women in our study felt that bone marker results and educational information were helpful to them, there was no difference in persistence between those who received either bone marker information and/or educational information and those who did not. Because of the unexpected rate of primary nonadherence, this study may be underpowered.

Amyloid precursor protein controls cholesterol turnover needed for neuronal activity

PubMed Central

Pierrot, Nathalie; Tyteca, Donatienne; D'auria, Ludovic; Dewachter, Ilse; Gailly, Philippe; Hendrickx, Aurélie; Tasiaux, Bernadette; Haylani, Laetitia El; Muls, Nathalie; N'Kuli, Francisca; Laquerrière, Annie; Demoulin, Jean-Baptiste; Campion, Dominique; Brion, Jean-Pierre; Courtoy, Pierre J; Kienlen-Campard, Pascal; Octave, Jean-Noël

2013-01-01

Perturbation of lipid metabolism favours progression of Alzheimer disease, in which processing of Amyloid Precursor Protein (APP) has important implications. APP cleavage is tightly regulated by cholesterol and APP fragments regulate lipid homeostasis. Here, we investigated whether up or down regulation of full-length APP expression affected neuronal lipid metabolism. Expression of APP decreased HMG-CoA reductase (HMGCR)-mediated cholesterol biosynthesis and SREBP mRNA levels, while its down regulation had opposite effects. APP and SREBP1 co-immunoprecipitated and co-localized in the Golgi. This interaction prevented Site-2 protease-mediated processing of SREBP1, leading to inhibition of transcription of its target genes. A GXXXG motif in APP sequence was critical for regulation of HMGCR expression. In astrocytes, APP and SREBP1 did not interact nor did APP affect cholesterol biosynthesis. Neuronal expression of APP decreased both HMGCR and cholesterol 24-hydroxylase mRNA levels and consequently cholesterol turnover, leading to inhibition of neuronal activity, which was rescued by geranylgeraniol, generated in the mevalonate pathway, in both APP expressing and mevastatin treated neurons. We conclude that APP controls cholesterol turnover needed for neuronal activity. PMID:23554170

Ubiquitin-dependent distribution of the transcriptional coactivator p300 in cytoplasmic inclusion bodies.

PubMed

Chen, Jihong; Halappanavar, Sabina; Th' ng, John P H; Li, Qiao

2007-01-01

The protein level of transcriptional coactivator p300, an essential nuclear protein, is critical to a broad array of cellular activities including embryonic development, cell differentiation and proliferation. We have previously established that histone deacetylase inhibitor such as valproic acid induces p300 degradation through the 26S proteasome pathway. Here, we report the roles of cellular trafficking and spatial redistribution in valproic acid-induced p300 turnover. Our study demonstrates that p300 is redistributed to the cytoplasm prior to valproic acid-induced turnover. Inhibition of proteasome-dependent protein degradation, does not prevent nucleo-cytoplasmic shuttling of p300, rather sequesters the cytoplasmic p300 to a distinct perinuclear region. In addition, the formation of p300 aggregates in the perinuclear region depends on functional microtubule networks and correlates with p300 ubiquitination. Our work establishes, for the first time, that p300 is also a substrate of the cytoplasmic ubiquitin-proteasome system and provides insight on how cellular trafficking and spatial redistribution regulate the availability and activity of transcriptional coactivator p300.

Bone turnover marker reference intervals in young females.

PubMed

Callegari, Emma T; Gorelik, Alexandra; Garland, Suzanne M; Chiang, Cherie Y; Wark, John D

2017-07-01

Background The use of bone turnover markers in clinical practice and research in younger people is limited by the lack of normative data and understanding of common causes of variation in bone turnover marker values in this demographic. To appropriately interpret bone turnover markers, robust reference intervals specific to age, development and sex are necessary. This study aimed to determine reference intervals of bone turnover markers in females aged 16-25 years participating in the Safe-D study. Methods Participants were recruited through social networking site Facebook and were asked to complete an extensive, online questionnaire and attend a site visit. Participants were tested for serum carboxy-terminal cross-linking telopeptide of type 1 collagen and total procollagen type 1 N-propeptide using the Roche Elecsys automated analyser. Reference intervals were determined using the 2.5th to 97.5th percentiles of normalized bone turnover marker values. Results Of 406 participants, 149 were excluded due to medical conditions or medication use (except hormonal contraception) which may affect bone metabolism. In the remaining 257 participants, the reference interval was 230-1000 ng/L for serum carboxy-terminal cross-linking telopeptide of type 1 collagen and 27-131  µg/L for procollagen type 1 N-propeptide. Both marker concentrations were inversely correlated with age and oral contraceptive pill use. Therefore, intervals specific to these variables were calculated. Conclusions We defined robust reference intervals for cross-linking telopeptide of type 1 collagen and procollagen type 1 N-propeptide in young females grouped by age and contraceptive pill use. We examined bone turnover markers' relationship with several lifestyle, clinical and demographic factors. Our normative intervals should aid interpretation of bone turnover markers in young females particularly in those aged 16 to 19 years where reference intervals are currently provisional.

Respiratory Therapist Job Perceptions: The Impact of Protocol Use.

PubMed

Metcalf, Ashley Y; Stoller, James K; Habermann, Marco; Fry, Timothy D

2015-11-01

Demand for respiratory care services and staffing levels of respiratory therapists (RTs) is expected to increase over the next several years. Hence, RT job satisfaction will be a critical factor in determining recruitment and retention of RTs. Determinants of RT job satisfaction measures have received little attention in the literature. This study examines the use of respiratory care protocols and associated levels of RT job satisfaction, turnover intentions, and job stress. Four-hundred eighty-one RTs at 44 hospitals responded to an online survey regarding job satisfaction, turnover intentions, and job stress. Random coefficient modeling was used for analysis and to account for the nested structure of the data. Higher levels of RT protocol use were associated with higher levels of job satisfaction, lower rates of turnover intentions, and lower levels of job stress. In addition, RTs with greater experience had higher levels of job satisfaction, and RTs working at teaching hospitals had lower rates of turnover intentions. The study extends prior research by examining how the use of respiratory care protocols favorably affects RTs' perceptions of job satisfaction, turnover intention, and job stress. In a time of increasing demand for respiratory care services, protocols may enhance retention of RTs. Copyright © 2015 by Daedalus Enterprises.

Abnormal intrinsic dynamics of dendritic spines in a fragile X syndrome mouse model in vivo.

PubMed

Nagaoka, Akira; Takehara, Hiroaki; Hayashi-Takagi, Akiko; Noguchi, Jun; Ishii, Kazuhiko; Shirai, Fukutoshi; Yagishita, Sho; Akagi, Takanori; Ichiki, Takanori; Kasai, Haruo

2016-05-25

Dendritic spine generation and elimination play an important role in learning and memory, the dynamics of which have been examined within the neocortex in vivo. Spine turnover has also been detected in the absence of specific learning tasks, and is frequently exaggerated in animal models of autistic spectrum disorder (ASD). The present study aimed to examine whether the baseline rate of spine turnover was activity-dependent. This was achieved using a microfluidic brain interface and open-dura surgery, with the goal of abolishing neuronal Ca(2+) signaling in the visual cortex of wild-type mice and rodent models of fragile X syndrome (Fmr1 knockout [KO]). In wild-type and Fmr1 KO mice, the majority of baseline turnover was found to be activity-independent. Accordingly, the application of matrix metalloproteinase-9 inhibitors selectively restored the abnormal spine dynamics observed in Fmr1 KO mice, without affecting the intrinsic dynamics of spine turnover in wild-type mice. Such findings indicate that the baseline turnover of dendritic spines is mediated by activity-independent intrinsic dynamics. Furthermore, these results suggest that the targeting of abnormal intrinsic dynamics might pose a novel therapy for ASD.

Mediating role of work engagement in the relationship between job resources and personal resources with turnover intention among female nurses.

PubMed

Shahpouri, Samira; Namdari, Kourosh; Abedi, Ahmad

2016-05-01

One of the latest models proposed with regard to work engagement is the detailed model put forward by Bakker and Demerouti (2007). The present study aims at investigating the effect of job resources and personal resources on turnover intention with the mediator role of work engagement among female nurses at Isfahan Alzahra Hospital. In the current study, job and personal resources were considered as the predictors of job turnover and work engagement was considered as the mediator variable among predictive and criterion variables. The data of the present study were collected from 208 female nurses who were selected by systematic random sampling. As for the analysis of the collected data, structural equations model, normal distribution method, and Bootstrap method in Macro, Preacher and Hayes, (2004) program were deployed. The findings showed that the personal resources affect the turnover intention both directly and indirectly (through work engagement); however, job resources are just associated with turnover intention with the mediating role of work engagement. The results of the study have important implications for organizations' managers about improving work engagement. Copyright © 2015 Elsevier Inc. All rights reserved.

Vitamins E and C may increase collagen turnover by intramuscular fibroblasts. Potential for improved meat quality.

PubMed

Archile-Contreras, Anangelina C; Cha, Ming C; Mandell, Ira B; Miller, Stephen P; Purslow, Peter P

2011-01-26

Vitamins influence collagen metabolism in animals grown for meat. This study investigated whether vitamins E and C regulate collagen turnover in muscle by the balance of effects on the synthesis of collagen and its degradation by secretion of matrix metalloproteinases (MMPs) by bovine intramuscular fibroblasts. Fibroblasts isolated from longissimus dorsi (LD) and semitendinosus (ST) muscle were treated with different concentrations of vitamins. Pro-MMP-2, MMP-2, and total soluble collagen (TSC) synthesis were determined. Vitamins E and C each preferentially increased (P < 0.05) MMP-2 in cells derived from LD relative to those derived from ST. Higher TSC values (P < 0.05) were found for ST cells than for LD cells. Both vitamins may increase collagen turnover exerted by intramuscular connective tissue fibroblasts. These results may have implications in vivo on animal production, as a high rate of collagen turnover may lead to increased collagen solubility in muscles, which can affect meat tenderness.

The effect of a smoke-free law on restaurant business in South Australia.

PubMed

Wakefield, Melanie; Siahpush, Mohammad; Scollo, Michelle; Lal, Anita; Hyland, Andrew; McCaul, Kieran; Miller, Caroline

2002-08-01

Despite evidence to the contrary from overseas research, the introduction of smoke-free legislation in South Australia (SA), which required all restaurants to go smoke-free in January 1999, sparked concerns among the hospitality industry about loss of restaurant business. This study aimed to determine whether the law had a detrimental impact on restaurant business in SA. Using time series analysis, we compared the ratio of monthly restaurant turnover from restaurants and cafés in SA to (a) total retail tumover in SA (minus restaurants) for the years 1991 to 2001 and (b) Australian restaurant tumover (minus SA, Westem Australia and the Australian Capital Territory) for the years 1991-2000. There was no decline in the ratio of (a) SA restaurant turnover to SA retail turnover or (b) SA restaurant tumover to Australian restaurant turnover. The introduction of a smoke-free law applying to restaurants in SA did not adversely affect restaurant business in SA.

Nursing churn and turnover in Australian hospitals: nurses perceptions and suggestions for supportive strategies

PubMed Central

2014-01-01

Background This study aimed to reveal nurses’ experiences and perceptions of turnover in Australian hospitals and identify strategies to improve retention, performance and job satisfaction. Nursing turnover is a serious issue that can compromise patient safety, increase health care costs and impact on staff morale. A qualitative design was used to analyze responses from 362 nurses collected from a national survey of nurses from medical and surgical nursing units across 3 Australian States/Territories. Method A qualitative design was used to analyze responses from 362 nurses collected from a national survey of nurses from medical and surgical nursing units across 3 Australian States/Territories. Results Key factors affecting nursing turnover were limited career opportunities; poor support; a lack of recognition; and negative staff attitudes. The nursing working environment is characterised by inappropriate skill-mix and inadequate patient-staff ratios; a lack of overseas qualified nurses with appropriate skills; low involvement in decision-making processes; and increased patient demands. These issues impacted upon heavy workloads and stress levels with nurses feeling undervalued and disempowered. Nurses described supportive strategies: improving performance appraisals, responsive preceptorship and flexible employment options. Conclusion Nursing turnover is influenced by the experiences of nurses. Positive steps can be made towards improving workplace conditions and ensuring nurse retention. Improving performance management and work design are strategies that nurse managers could harness to reduce turnover. PMID:24708565

Nursing churn and turnover in Australian hospitals: nurses perceptions and suggestions for supportive strategies.

PubMed

Dawson, Angela J; Stasa, Helen; Roche, Michael A; Homer, Caroline S E; Duffield, Christine

2014-04-08

This study aimed to reveal nurses' experiences and perceptions of turnover in Australian hospitals and identify strategies to improve retention, performance and job satisfaction. Nursing turnover is a serious issue that can compromise patient safety, increase health care costs and impact on staff morale. A qualitative design was used to analyze responses from 362 nurses collected from a national survey of nurses from medical and surgical nursing units across 3 Australian States/Territories. A qualitative design was used to analyze responses from 362 nurses collected from a national survey of nurses from medical and surgical nursing units across 3 Australian States/Territories. Key factors affecting nursing turnover were limited career opportunities; poor support; a lack of recognition; and negative staff attitudes. The nursing working environment is characterised by inappropriate skill-mix and inadequate patient-staff ratios; a lack of overseas qualified nurses with appropriate skills; low involvement in decision-making processes; and increased patient demands. These issues impacted upon heavy workloads and stress levels with nurses feeling undervalued and disempowered. Nurses described supportive strategies: improving performance appraisals, responsive preceptorship and flexible employment options. Nursing turnover is influenced by the experiences of nurses. Positive steps can be made towards improving workplace conditions and ensuring nurse retention. Improving performance management and work design are strategies that nurse managers could harness to reduce turnover.

Study on Effects of Different Replacement Rate on Bending Behavior of Big Recycled Aggregate Self Compacting Concrete

NASA Astrophysics Data System (ADS)

Li, Jing; Guo, Tiantian; Gao, Shuai; Jiang, Lin; Zhao, Zhijun; Wang, Yalin

2018-03-01

Big recycled aggregate self compacting concrete is a new type of recycled concrete, which has the advantages of low hydration heat and green environmental protection, but its bending behavior can be affected by different replacement rate. Therefor, in this paper, the research status of big Recycled aggregate self compacting concrete was systematically introduced, and the effect of different replacement rate of big recycled aggregate on failure mode, crack distribution and bending strength of the beam were studied through the bending behavior test of 4 big recycled aggregate self compacting concrete beams. The results show that: The crack distribution of the beam can be affected by the replacement rate; The failure modes of big recycled aggregate beams are the same as those of ordinary concrete; The plane section assumption is applicable to the big recycled aggregate self compacting concrete beam; The higher the replacement rate, the lower the bending strength of big recycled aggregate self compacting concrete beams.

The economic cost of using restraint and the value added by restraint reduction or elimination.

PubMed

Lebel, Janice; Goldstein, Robert

2005-09-01

The purpose of this study was to calculate the economic cost of using restraint on one adolescent inpatient service and to examine the effect of an initiative to reduce or eliminate the use of restraint after it was implemented. A detailed process-task analysis of mechanical, physical, and medication-based restraint was conducted in accordance with state and federal restraint requirements. Facility restraint data were collected, verified, and analyzed. A model was developed to determine the cost and duration of an average episode for each type of restraint. Staff time allocated to restraint activities and medication costs were computed. Calculation of the cost of restraint was restricted to staff and medication costs. Aggregate costs of restraint use and staff-related costs for one full year before the restraint reduction initiative (FY 2000) and one full year after the initiative (FY 2003) were calculated. Outcome, discharge, and recidivism data were analyzed. A comparison of the FY 2000 data with the FY 2003 data showed that the adolescent inpatient service's aggregate use of restraint decreased from 3,991 episodes to 373 episodes (91 percent), which was associated with a reduction in the cost of restraint from $1,446,740 to $117,036 (a 92 percent reduction). In addition, sick time, staff turnover and replacement costs, workers' compensation, injuries to adolescents and staff, and recidivism decreased. Adolescent Global Assessment of Functioning scores at discharge significantly improved. Implementation of a restraint reduction initiative was associated with a reduction in the use of restraint, staff time devoted to restraint, and staff-related costs. This shift appears to have contributed to better outcomes for adolescents, fewer injuries to adolescents and staff, and lower staff turnover. The initiative may have enhanced adolescent treatment and work conditions for staff.

Soil carbon stabilization and turnover at alley-cropping systems, Eastern Germany

NASA Astrophysics Data System (ADS)

Medinski, T.; Freese, D.

2012-04-01

Alley-cropping system is seen as a viable land-use practice for mitigation of greenhouse gas CO2, energy-wood production and soil carbon sequestration. The extent to which carbon is stored in soil varies between ecosystems, and depends on tree species, soil types and on the extent of physical protection of carbon within soil aggregates. This study investigates soil carbon sequestration at alley-cropping systems presented by alleys of fast growing tree species (black locust and poplar) and maize, in Brandenburg, Eastern Germany. Carbon accumulation and turnover are assessed by measuring carbon fractions differing in decomposition rates. For this purpose soil samples were fractionated into labile and recalcitrant soil-size fractions by wet-sieving: macro (>250 µm), micro (53-250 µm) and clay + silt (<53 µm), followed by determination of organic carbon and nitrogen by gas-chromatography. Soil samples were also analysed for the total C&N content, cold-water extractable OC, and microbial C. Litter decomposition was evaluated by litter bags experiment. Soil CO2 flux was measured by LiCor automated device LI-8100A. No differences for the total and stable (clay+silt, <53 µm) carbon fraction were observed between treatment. While cold water-extractable carbon was significantly higher at maize alley compared to black locust alley. This may indicate faster turnover of organic matter at maize alley due to tillage, which influenced greater incorporation of plant residues into the soil, greater soil respiration and microbial activity.

Numerical calculations of spectral turnover and synchrotron self-absorption in CSS and GPS radio sources

NASA Astrophysics Data System (ADS)

Jeyakumar, S.

2016-06-01

The dependence of the turnover frequency on the linear size is presented for a sample of Giga-hertz Peaked Spectrum and Compact Steep Spectrum radio sources derived from complete samples. The dependence of the luminosity of the emission at the peak frequency with the linear size and the peak frequency is also presented for the galaxies in the sample. The luminosity of the smaller sources evolve strongly with the linear size. Optical depth effects have been included to the 3D model for the radio source of Kaiser to study the spectral turnover. Using this model, the observed trend can be explained by synchrotron self-absorption. The observed trend in the peak-frequency-linear-size plane is not affected by the luminosity evolution of the sources.

Is the effect of person-organisation fit on turnover intention mediated by job satisfaction? A survey of community health workers in China.

PubMed

Zhang, Mingji; Yan, Fei; Wang, Wei; Li, Guohong

2017-02-22

Person-organisation fit (P-O fit) is a predictor of work attitude. However, in the area of human resource for health, the literature of P-O fit is quite limited. It is unclear whether P-O fit directly or indirectly affects turnover intention. This study aims to examine the mediation effect of job satisfaction on the relationship between P-O fit and turnover intention based on data from China. This is a cross-sectional survey of community health workers (CHWs) in China in 2013. A questionnaire of P-O fit, job satisfaction and turnover intention was developed, and its validity and reliability were assessed. Multiple regression and structural equation modelling were used to examine the relationship among P-O fit, job satisfaction and turnover intention. Multistage sampling was applied. In total, 656 valid questionnaire responses were collected from CHWs in four provincial regions in China, namely Shanghai, Shaanxi, Shandong and Anhui. P-O fit was directly related to job satisfaction (standardised β 0.246) and inversely related to turnover intention (standardised β -0.186). In the mediation model, the total effect of P-O fit on turnover intention was -0.186 (p<0.001); the direct effect of P-O fit on turnover intention was -0.094 (p<0.01); the indirect effect of job satisfaction on the relationship between P-O fit and turnover intention was -0.092 (p<0.001). The effect of P-O fit on turnover intention was partially mediated through job satisfaction. It is suggested that more work attitude variables and different dimensions of P-O fit be taken into account to examine the complete mechanism of person-organisation interaction. Indirect measures of P-O fit should be encouraged in practice to enhance work attitudes of health workers. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

7 CFR 51.1564 - External defects.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the potato or when green color affects more than 50 percent of the surface in the aggregate. Growth Cracks When the growth crack(s) affects more than 1/2 the length of the potato in the aggregate on round... that as outlined in Table V. (See Table V.) When the growth crack(s) affects more than 3/4 the length...

Protein Quality Control by Molecular Chaperones in Neurodegeneration

PubMed Central

Ciechanover, Aaron; Kwon, Yong Tae

2017-01-01

Protein homeostasis (proteostasis) requires the timely degradation of misfolded proteins and their aggregates by protein quality control (PQC), of which molecular chaperones are an essential component. Compared with other cell types, PQC in neurons is particularly challenging because they have a unique cellular structure with long extensions. Making it worse, neurons are postmitotic, i.e., cannot dilute toxic substances by division, and, thus, are highly sensitive to misfolded proteins, especially as they age. Failure in PQC is often associated with neurodegenerative diseases, such as Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD), and prion disease. In fact, many neurodegenerative diseases are considered to be protein misfolding disorders. To prevent the accumulation of disease-causing aggregates, neurons utilize a repertoire of chaperones that recognize misfolded proteins through exposed hydrophobic surfaces and assist their refolding. If such an effort fails, chaperones can facilitate the degradation of terminally misfolded proteins through either the ubiquitin (Ub)-proteasome system (UPS) or the autophagy-lysosome system (hereafter autophagy). If soluble, the substrates associated with chaperones, such as Hsp70, are ubiquitinated by Ub ligases and degraded through the proteasome complex. Some misfolded proteins carrying the KFERQ motif are recognized by the chaperone Hsc70 and delivered to the lysosomal lumen through a process called, chaperone-mediated autophagy (CMA). Aggregation-prone misfolded proteins that remain unprocessed are directed to macroautophagy in which cargoes are collected by adaptors, such as p62/SQSTM-1/Sequestosome-1, and delivered to the autophagosome for lysosomal degradation. The aggregates that have survived all these refolding/degradative processes can still be directly dissolved, i.e., disaggregated by chaperones. Studies have shown that molecular chaperones alleviate the pathogenic symptoms by neurodegeneration-causing protein aggregates. Chaperone-inducing drugs and anti-aggregation drugs are actively exploited for beneficial effects on symptoms of disease. Here, we discuss how chaperones protect misfolded proteins from aggregation and mediate the degradation of terminally misfolded proteins in collaboration with cellular degradative machinery. The topics also include therapeutic approaches to improve the expression and turnover of molecular chaperones and to develop anti-aggregation drugs. PMID:28428740

Decreased bone turnover with balanced resorption and formation prevent cortical bone loss during disuse (hibernation) in grizzly bears (Ursus arctos horribilis).

PubMed

McGee, Meghan E; Maki, Aaron J; Johnson, Steven E; Nelson, O Lynne; Robbins, Charles T; Donahue, Seth W

2008-02-01

Disuse uncouples bone formation from resorption, leading to increased porosity, decreased bone geometrical properties, and decreased bone mineral content which compromises bone mechanical properties and increases fracture risk. However, black bear bone properties are not adversely affected by aging despite annual periods of disuse (i.e., hibernation), which suggests that bears either prevent bone loss during disuse or lose bone and subsequently recover it at a faster rate than other animals. Here we show decreased cortical bone turnover during hibernation with balanced formation and resorption in grizzly bear femurs. Hibernating grizzly bear femurs were less porous and more mineralized, and did not demonstrate any changes in cortical bone geometry or whole bone mechanical properties compared to active grizzly bear femurs. The activation frequency of intracortical remodeling was 75% lower during hibernation than during periods of physical activity, but the normalized mineral apposition rate was unchanged. These data indicate that bone turnover decreases during hibernation, but osteons continue to refill at normal rates. There were no changes in regional variation of porosity, geometry, or remodeling indices in femurs from hibernating bears, indicating that hibernation did not preferentially affect one region of the cortex. Thus, grizzly bears prevent bone loss during disuse by decreasing bone turnover and maintaining balanced formation and resorption, which preserves bone structure and strength. These results support the idea that bears possess a biological mechanism to prevent disuse osteoporosis.

The effect of chemical agents on the turnover of the bound phosphate associated with the sodium-and-potassium ion-stimulated adenosine triphosphatase in ox brain microsomes

PubMed Central

Rodnight, R.

1970-01-01

1. The effect of chemical agents on the turnover of the Na+-dependent bound phosphate and the simultaneous Na+-dependent hydrolysis of ATP by a membrane preparation from ox brain was studied at an ATP/protein ratio of 12.5pmol/μg. 2. The agents were added immediately after phosphorylation of the preparation in a medium containing 50mm-sodium chloride and 2.5μm-[γ-32P]ATP. 3. Concentrations of sodium chloride above 150mm, calcium chloride to 20mm and suramin to 1.4mm inhibited both phosphorylation and dephosphorylation and concomitantly slowed ATP hydrolysis. At 125mm-sodium chloride dephosphorylation and hydrolysis were slightly slowed without affecting phosphorylation. 4. Ethanol to 1.6m concentration inhibited dephosphorylation without affecting phosphorylation; the bound phosphate was increased and ATP hydrolysis slowed. 5. Ouabain to 4mm concentration partially inhibited ATP hydrolysis and caused a transient (1–2s) rise in bound phosphate followed by a rapid fall to a lower plateau value, which eventually declined to zero by the time ATP hydrolysis was complete. 6. Of the detergents examined Lubrol W, Triton X-100 and sodium deoxycholate had no significant effect on turnover. Sodium dodecyl sulphate and sodium decyl sulphate to 3.5mm and 20mm respectively completely inhibited turnover and ATP hydrolysis and stabilized the bound phosphate. PMID:4250238

Safety organizing, emotional exhaustion, and turnover in hospital nursing units.

PubMed

Vogus, Timothy J; Cooil, Bruce; Sitterding, Mary; Everett, Linda Q

2014-10-01

Prior research has found that safety organizing behaviors of registered nurses (RNs) positively impact patient safety. However, little research exists on how engaging in safety organizing affects caregivers. While we know that organizational processes can have divergent effects on organizational and employee outcomes, little research exists on the effects of pursuing highly reliable performance through safety organizing on caregivers. Specifically, we examined whether, and the conditions under which, safety organizing affects RN emotional exhaustion and nursing unit turnover rates. Subjects included 1352 RNs in 50 intensive care, internal medicine, labor, and surgery nursing units in 3 Midwestern acute-care hospitals who completed questionnaires between August and December 2011 and 50 Nurse Managers from the units who completed questionnaires in December 2012. Cross-sectional analyses of RN emotional exhaustion linked to survey data on safety organizing and hospital incident reporting system data on adverse event rates for the year before survey administration. Cross-sectional analysis of unit-level RN turnover rates for the year following the administration of the survey linked to survey data on safety organizing. Multilevel regression analysis indicated that safety organizing was negatively associated with RN emotional exhaustion on units with higher rates of adverse events and positively associated with RN emotional exhaustion with lower rates of adverse events. Tobit regression analyses indicated that safety organizing was associated with lower unit level of turnover rates over time. Safety organizing is beneficial to caregivers in multiple ways, especially on nursing units with high levels of adverse events and over time.

Protein turnover and cellular stress in mildly and severely affected muscles from patients with limb girdle muscular dystrophy type 2I.

PubMed

Hauerslev, Simon; Sveen, Marie L; Vissing, John; Krag, Thomas O

2013-01-01

Patients with Limb girdle muscular dystrophy type 2I (LGMD2I) are characterized by progressive muscle weakness and wasting primarily in the proximal muscles, while distal muscles often are spared. Our aim was to investigate if wasting could be caused by impaired regeneration in the proximal compared to distal muscles. Biopsies were simultaneously obtained from proximal and distal muscles of the same patients with LGMD2I (n = 4) and healthy subjects (n = 4). The level of past muscle regeneration was evaluated by counting internally nucleated fibers and determining actively regenerating fibers by using the developmental markers embryonic myosin heavy chain (eMHC) and neural cell adhesion molecule (NCAM) and also assessing satellite cell activation status by myogenin positivity. Severe muscle histopathology was occasionally observed in the proximal muscles of patients with LGMD2I whereas distal muscles were always relatively spared. No difference was found in the regeneration markers internally nucleated fibers, actively regenerating fibers or activation status of satellite cells between proximal and distal muscles. Protein turnover, both synthesis and breakdown, as well as cellular stress were highly increased in severely affected muscles compared to mildly affected muscles. Our results indicate that alterations in the protein turnover and myostatin levels could progressively impair the muscle mass maintenance and/or regeneration resulting in gradual muscular atrophy.

The Combined Influence of Affective, Continuance and Normative Commitment on Employee Withdrawal

ERIC Educational Resources Information Center

Somers, Mark John

2009-01-01

In a sample of 288 hospital nurses, commitment profiles were compared to turnover intentions, job search behavior, work withdrawal (absenteeism and lateness) and job stress. Five empirically-derived commitment profiles emerged: highly committed, affective-normative dominant, continuance-normative dominant, continuance dominant, and uncommitted.…

The 'big dip': decrements in RN satisfaction at mid-career.

PubMed

Coshow, Suzanne M; Davis, Paul; Wolosin, Robert J

2009-01-01

In response to nurse turnover, hospitals have taken steps to ensure that their nurses are satisfied with their jobs. On-boarding may not be the most pressing retention issue facing health care organizations as the loss of mid-career nurses may be the larger problem. There are some areas of work satisfaction for nurses which may be more responsive to organizational efforts to reach higher aggregate levels of satisfaction. Health care organizations may due well to focus on the relative satisfaction of their mid-career nurses. Opportunities to increase nurse job satisfaction across different facets of work may be an effective strategy to address retention.

Oxidative stress-induced autophagy: Role in pulmonary toxicity

PubMed Central

Malaviya, Rama; Laskin, Jeffrey D.; Laskin, Debra L.

2015-01-01

Autophagy is an evolutionarily conserved catabolic process important in regulating the turnover of essential proteins and in elimination of damaged organelles and protein aggregates. Autophagy is observed in the lung in response to oxidative stress generated as a consequence of exposure to environmental toxicants. Whether autophagy plays role in promoting cell survival or cytotoxicity is unclear. In this article recent findings on oxidative stress-induced autophagy in the lung are reviewed; potential mechanisms initiating autophagy are also discussed. A better understanding of autophagy and its role in pulmonary toxicity may lead to the development of new strategies to treat lung injury associated with oxidative stress. PMID:24398106

Aggregation protects flexible-shelled reptile eggs from severe hydric stress.

PubMed

Marco, Adolfo; Díaz-Paniagua, Carmen

2008-03-01

Many reptiles lay eggs with flexible shells that can progressively lose water until lethal dehydration under dry soil conditions. The number of eggs that develop together may influence the water exchange in the nest. We hypothesise that egg aggregation could reduce water lost under dry conditions. We exposed aggregated and isolated eggs to severe hydric stress followed by a period of rehydration. Hydric stress caused a general loss of water in common chameleon eggs. Initial egg mass did not affect survival but eggs that had lost more water had higher mortality and produced smaller hatchlings. Mass loss was higher and even lethal for isolated Chamaeleo chameleon eggs. However, aggregated eggs lost less water and most survived this period. After hydric stress, all surviving eggs gained mass via water absorption, and aggregation negatively affected water uptake. Isolated eggs hatched at smaller sizes than aggregated eggs. Aggregation also favoured hatching synchrony. Large clutches may favour hatching success of terrestrial flexible-shelled eggs incubated under severe drought conditions.

Aggregate stability and water retention near saturation characteristics as affected by soil texture, aggregate size and polyacrylamide application

USDA-ARS?s Scientific Manuscript database

Understanding the effects of soil intrinsic properties and extrinsic conditions on aggregate stability is essential for the development of effective soil and water conservation practices. Our objective was to evaluate the combined role of soil texture, aggregate size and application of a stabilizing...

Use of video-feedback, reflection, and interactive analysis to improve nurse leadership practices.

PubMed

Crenshaw, Jeannette T

2012-01-01

The chronic shortage of registered nurses (RNs) affects patient safety and health care quality. Many factors affect the RN shortage in the workforce, including negative work environments, exacerbated by ineffective leadership approaches. Improvements in the use of relationship-based leadership approaches lead to healthier work environments that foster RN satisfaction and reduce RN turnover and vacancy rates in acute care settings. In this article, an innovative approach to reduce nurse turnover and decrease vacancy rates in acute care settings is described. Video feedback with reflection and interactive analysis is an untapped resource for nurse leaders and aspiring nurse leaders in their development of effective leadership skills. This unique method may be an effective leadership strategy for addressing recruitment and retention issues in a diverse workforce.

Thermal aggregation of glycated bovine serum albumin.

PubMed

Rondeau, Philippe; Navarra, Giovanna; Cacciabaudo, Francesco; Leone, Maurizio; Bourdon, Emmanuel; Militello, Valeria

2010-04-01

Aggregation and glycation processes in proteins have a particular interest in medicine fields and in food technology. Serum albumins are model proteins which are able to self-assembly in aggregates and also sensitive to a non-enzymatic glycation in cases of diabetes. In this work, we firstly reported a study on the glycation and oxidation effects on the structure of bovine serum albumin (BSA). The experimental approach is based on the study of conformational changes of BSA at secondary and tertiary structures by FTIR absorption and fluorescence spectroscopy, respectively. Secondly, we analysed the thermal aggregation process on BSA glycated with different glucose concentrations. Additional information on the aggregation kinetics are obtained by light scattering measurements. The results show that glycation process affects the native structure of BSA. Then, the partial unfolding of the tertiary structure which accompanies the aggregation process is similar both in native and glycated BSA. In particular, the formation of aggregates is progressively inhibited with growing concentration of glucose incubated with BSA. These results bring new insights on how aggregation process is affected by modification of BSA induced by glycation. Copyright 2009 Elsevier B.V. All rights reserved.

El Niño drought increased canopy turnover in Amazon forests.

PubMed

Leitold, Veronika; Morton, Douglas C; Longo, Marcos; Dos-Santos, Maiza Nara; Keller, Michael; Scaranello, Marcos

2018-03-25

Amazon droughts, including the 2015-2016 El Niño, may reduce forest net primary productivity and increase canopy tree mortality, thereby altering both the short- and the long-term net forest carbon balance. Given the broad extent of drought impacts, inventory plots or eddy flux towers may not capture regional variability in forest response to drought. We used multi-temporal airborne Lidar data and field measurements of coarse woody debris to estimate patterns of canopy turnover and associated carbon losses in intact and fragmented forests in the central Brazilian Amazon between 2013-2014 and 2014-2016. Average annualized canopy turnover rates increased by 65% during the drought period in both intact and fragmented forests. The average size and height of turnover events was similar for both time intervals, in contrast to expectations that the 2015-2016 El Niño drought would disproportionally affect large trees. Lidar-biomass relationships between canopy turnover and field measurements of coarse woody debris were modest (R 2  ≈ 0.3), given similar coarse woody debris production and Lidar-derived changes in canopy volume from single tree and multiple branch fall events. Our findings suggest that El Niño conditions accelerated canopy turnover in central Amazon forests, increasing coarse woody debris production by 62% to 1.22 Mg C ha -1  yr -1 in drought years . No claim to original US Government works New Phytologist © 2018 New Phytologist Trust.

A study of relationship between job stress, quality of working life and turnover intention among hospital employees.

PubMed

Mosadeghrad, Ali Mohammad; Ferlie, Ewan; Rosenberg, Duska

2011-11-01

Job stress is a serious threat to the quality of working life (QWL) of health-care employees and can cause hostility, aggression, absenteeism and turnover, as well as reduced productivity. In addition, job stress among employees affects the quality of health-care services. The purpose of this study was to gain a better understanding of the relationships between job stress and QWL of employees, and their impact on turnover intention at Isfahan hospitals, Iran. The study employed a cross-sectional research design. A validated questionnaire was used to collect data from hospital employees. Overall, 26% of employees graded their job stress high. The major sources of stress were inadequate pay, inequality at work, too much work, staff shortage, lack of recognition and promotion prospects, time pressure, lack of job security and lack of management support. An inverse relationship was found between job stress and QWL among hospital employees. The most important predictor of QWL was disturbance handling, followed by job proud, job security and job stress. Finally, while QWL was negatively associated with turnover intentions, job stress was positively related to employees' intention to quit. Since job stress has a strong correlation with employee QWL and turnover intention, it is very important to apply the right human resources policies to increase employees' QWL and decrease subsequent turnover. This study invites further research to explore, implement and evaluate intervention strategies for prevention of occupational stress and improvement in QWL.

Workplace violence against nurses in Korea and its impact on professional quality of life and turnover intention.

PubMed

Choi, Seung-Hye; Lee, Haeyoung

2017-10-01

To inform countermeasures against nurses' workplace violence by reviewing the experience of violence. Violence is an important issue in medical settings that influences turnover intention of nurses. However, few studies have dealt with the effects of violence experienced by nurses on professional quality of life and turnover intention. A descriptive study using a structured questionnaire and data were analysed using t-test, one-way anova and hierarchical multiple regression analysis. Of 358 nurses 95.5% reported that they had experienced workplace violence during the previous 1 year. Findings indicated that turnover intention was positively associated with years worked as a nurse, functional nursing delivery system, exposure types of violence with physical threats, and mild or severe burnout. Nurses experienced diverse workplace violence, which could decrease their professional quality of life and be a factor affecting their turnover intention. Role of leadership in creating a positive work environment is needed. Prevention of workplace violence should focus on at-risk groups to reduce workplace violence. Workplace violence should be communicated regularly and feedback should be given if there is unintentional non-physical violence. In particular it is important to investigate post-violence management in nurses who have experienced violence to reduce secondary trauma. © 2017 John Wiley & Sons Ltd.

The impact of organisational factors on horizontal bullying and turnover intentions in the nursing workplace.

PubMed

Blackstock, Sheila; Harlos, Karen; Macleod, Martha L P; Hardy, Cindy L

2015-11-01

To examine the impact of organisational factors on bullying among peers (i.e. horizontal) and its effect on turnover intentions among Canadian registered nurses (RNs). Bullying among nurses is an international problem. Few studies have examined factors specific to nursing work environments that may increase exposure to bullying. An Australian model of nurse bullying was tested among Canadian registered nurse coworkers using a web-based survey (n = 103). Three factors - misuse of organisational processes/procedures, organisational tolerance and reward of bullying, and informal organisational alliances - were examined as predictors of horizontal bullying, which in turn was examined as a predictor of turnover intentions. The construct validity of model measures was explored. Informal organisational alliances and misuse of organisational processes/procedures predicted increased horizontal bullying that, in turn, predicted increased turnover intentions. Construct validity of model measures was supported. Negative informal alliances and misuse of organisational processes are antecedents to bullying, which adversely affects employment relationship stability. The results suggest that reforming flawed organisational processes that contribute to registered nurses' bullying experiences may help to reduce chronically high turnover. Nurse leaders and managers need to create workplace processes that foster positive networks, fairness and respect through more transparent and accountable practices. © 2014 John Wiley & Sons Ltd.

Multiple Cellular Responses to Serotonin Contribute to Epithelial Homeostasis

PubMed Central

Pai, Vaibhav P.; Horseman, Nelson D.

2011-01-01

Epithelial homeostasis incorporates the paradoxical concept of internal change (epithelial turnover) enabling the maintenance of anatomical status quo. Epithelial cell differentiation and cell loss (cell shedding and apoptosis) form important components of epithelial turnover. Although the mechanisms of cell loss are being uncovered the crucial triggers that modulate epithelial turnover through regulation of cell loss remain undetermined. Serotonin is emerging as a common autocrine-paracine regulator in epithelia of multiple organs, including the breast. Here we address whether serotonin affects epithelial turnover. Specifically, serotonin's roles in regulating cell shedding, apoptosis and barrier function of the epithelium. Using in vivo studies in mouse and a robust model of differentiated human mammary duct epithelium (MCF10A), we show that serotonin induces mammary epithelial cell shedding and disrupts tight junctions in a reversible manner. However, upon sustained exposure, serotonin induces apoptosis in the replenishing cell population, causing irreversible changes to the epithelial membrane. The staggered nature of these events induced by serotonin slowly shifts the balance in the epithelium from reversible to irreversible. These finding have very important implications towards our ability to control epithelial regeneration and thus address pathologies of aberrant epithelial turnover, which range from degenerative disorders (e.g.; pancreatitis and thyrioditis) to proliferative disorders (e.g.; mastitis, ductal ectasia, cholangiopathies and epithelial cancers). PMID:21390323

Temporal issues in person-organization fit, person-job fit and turnover: The role of leader-member exchange.

PubMed

Boon, Corine; Biron, Michal

2016-12-01

Person-environment fit has been found to have significant implications for employee attitudes and behaviors. Most research to date has approached person-environment fit as a static phenomenon, and without examining how different types of person-environment fit may affect each other. In particular, little is known about the conditions under which fit with one aspect of the environment influences another aspect, as well as subsequent behavior. To address this gap we examine the role of leader-member exchange in the relationship between two types of person-environment fit over time: person-organization and person-job fit, and subsequent turnover. Using data from two waves (T1 and T2, respectively) and turnover data collected two years later (T3) from a sample of 160 employees working in an elderly care organization in the Netherlands, we find that person-organization fit at T1 is positively associated with person-job fit at T2, but only for employees in high-quality leader-member exchange relationships. Higher needs-supplies fit at T2 is associated with lower turnover at T3. In contrast, among employees in high-quality leader-member exchange relationships, the demands-abilities dimension of person-job fit at T2 is associated with higher turnover at T3.

Temporal issues in person–organization fit, person–job fit and turnover: The role of leader–member exchange

PubMed Central

Boon, Corine; Biron, Michal

2016-01-01

Person–environment fit has been found to have significant implications for employee attitudes and behaviors. Most research to date has approached person–environment fit as a static phenomenon, and without examining how different types of person–environment fit may affect each other. In particular, little is known about the conditions under which fit with one aspect of the environment influences another aspect, as well as subsequent behavior. To address this gap we examine the role of leader–member exchange in the relationship between two types of person–environment fit over time: person–organization and person–job fit, and subsequent turnover. Using data from two waves (T1 and T2, respectively) and turnover data collected two years later (T3) from a sample of 160 employees working in an elderly care organization in the Netherlands, we find that person–organization fit at T1 is positively associated with person–job fit at T2, but only for employees in high-quality leader–member exchange relationships. Higher needs–supplies fit at T2 is associated with lower turnover at T3. In contrast, among employees in high-quality leader–member exchange relationships, the demands–abilities dimension of person–job fit at T2 is associated with higher turnover at T3. PMID:27904171

Employees’ Organizational Identification and Affective Organizational Commitment: An Integrative Approach

PubMed Central

Stinglhamber, Florence; Marique, Géraldine; Caesens, Gaëtane; Desmette, Donatienne; Hansez, Isabelle; Hanin, Dorothée; Bertrand, Françoise

2015-01-01

Although several studies have empirically supported the distinction between organizational identification (OI) and affective commitment (AC), there is still disagreement regarding how they are related. Precisely, little attention has been given to the direction of causality between these two constructs and as to why they have common antecedents and outcomes. This research was designed to fill these gaps. Using a cross-lagged panel design with two measurement times, Study 1 examined the directionality of the relationship between OI and AC, and showed that OI is positively related to temporal change in AC, confirming the antecedence of OI on AC. Using a cross-sectional design, Study 2 investigated the mediating role of OI in the relationship between three work experiences (i.e., perceived organizational support, leader-member exchange, and job autonomy) and AC, and found that OI partially mediates the influence of work experiences on AC. Finally, Study 3 examined longitudinally how OI and AC combine in the prediction of actual turnover, and showed that AC totally mediates the relationship between OI and turnover. Overall, these findings suggest that favorable work experiences operate via OI to increase employees' AC that, in turn, decreases employee turnover. PMID:25875086

Employees' organizational identification and affective organizational commitment: an integrative approach.

PubMed

Stinglhamber, Florence; Marique, Géraldine; Caesens, Gaëtane; Desmette, Donatienne; Hansez, Isabelle; Hanin, Dorothée; Bertrand, Françoise

2015-01-01

Although several studies have empirically supported the distinction between organizational identification (OI) and affective commitment (AC), there is still disagreement regarding how they are related. Precisely, little attention has been given to the direction of causality between these two constructs and as to why they have common antecedents and outcomes. This research was designed to fill these gaps. Using a cross-lagged panel design with two measurement times, Study 1 examined the directionality of the relationship between OI and AC, and showed that OI is positively related to temporal change in AC, confirming the antecedence of OI on AC. Using a cross-sectional design, Study 2 investigated the mediating role of OI in the relationship between three work experiences (i.e., perceived organizational support, leader-member exchange, and job autonomy) and AC, and found that OI partially mediates the influence of work experiences on AC. Finally, Study 3 examined longitudinally how OI and AC combine in the prediction of actual turnover, and showed that AC totally mediates the relationship between OI and turnover. Overall, these findings suggest that favorable work experiences operate via OI to increase employees' AC that, in turn, decreases employee turnover.

Does drought legacy alter the recovery of grassland carbon dynamics from drought?

NASA Astrophysics Data System (ADS)

Bahn, M.; Hasibeder, R.; Fuchslueger, L.; Ingrisch, J.; Ladreiter-Knauss, T.; Lair, G.; Reinthaler, D.; Richter, A.; Kaufmann, R.

2016-12-01

Climate projections suggest an increase in the frequency and the severity of extreme climatic events, such as droughts, with consequences for the carbon cycle and its feedbacks to the climate system. An important implication of increasing drought frequency is that possible legacies of previous droughts may increasingly affect ecosystem responses to new drought events, though this has been rarely tested. Based on a series of severe experimental droughts performed during nine subsequent years on a mountain grassland in the Austrian Alps, we present evidence of effects of drought legacies on the recovery of grassland carbon dynamics from drought and analyse the underlying mechanisms. Both single and recurrent droughts led to increased aboveground productivity during drought recovery relative to control plots, favoring the biomass production and leaf area of grass species more strongly than of forbs. Belowground productivity was significantly increased during recovery. This led to higher total root length, even though specific root length was strongly reduced during recovery, particularly after recurrent drought events. Following rewetting, the temperature dependence of soil respiration was increasingly diminished and the Birch effect declined with progressive recurrence of droughts. This was paralleled by a change in soil aggregate stability and soil porosity in plots repeatedly exposed to drought. Pulse-labelling experiments revealed effects of drought legacy on plant carbon uptake and belowground allocation and altered microbial turnover of recent plant-derived carbon during and after a subsequent drought. Shifts in tissue nitrogen concentration indicate that drought effects on soil nitrogen turnover and availability could play an important role in the recovery of grassland carbon dynamics following both single and recurrent droughts. In conclusion, drought legacies can alter the recovery of grassland carbon dynamics from drought, the effects increasing with increasing drought frequency and involving changes in both plant functional composition and soil structure and processes.

Does drought legacy alter the recovery of grassland carbon dynamics from drought?

NASA Astrophysics Data System (ADS)

Bahn, Michael; Hasibeder, Roland; Fuchslueger, Lucia; Ingrisch, Johannes; Ladreiter-Knauss, Thomas; Lair, Georg; Reinthaler, David; Richter, Andreas; Kaufmann, Rüdiger

2017-04-01

Climate projections suggest an increase in the frequency and the severity of extreme climatic events, such as droughts, with consequences for the carbon cycle and its feedbacks to the climate system. An important implication of increasing drought frequency is that possible legacies of previous droughts may increasingly affect ecosystem responses to new drought events, though this has been rarely tested. Based on a series of severe experimental droughts performed during nine subsequent years on a mountain grassland in the Austrian Alps, we present evidence of effects of drought legacies on the recovery of grassland carbon dynamics from drought and analyse the underlying mechanisms. Both single and recurrent droughts led to increased aboveground productivity during drought recovery relative to control plots, favoring the biomass production and leaf area of grass species more strongly than of forbs. Belowground productivity was significantly increased during recovery. This led to higher total root length, even though specific root length was strongly reduced during recovery, particularly after recurrent drought events. Following rewetting, the temperature dependence of soil respiration was increasingly diminished and the Birch effect declined with progressive recurrence of droughts. This was paralleled by a change in soil aggregate stability and soil porosity in plots repeatedly exposed to drought. Isotopic pulse-labelling experiments revealed effects of drought legacy on plant carbon uptake and belowground allocation and altered microbial turnover of recent plant-derived carbon during and after a subsequent drought. Shifts in tissue nitrogen concentration indicate that drought effects on soil nitrogen turnover and availability could play an important role in the recovery of grassland carbon dynamics following both single and recurrent droughts. In conclusion, drought legacies can alter the recovery of grassland carbon dynamics from drought, the effects increasing with increasing drought frequency and involving changes in both plant functional composition and soil structure and processes.

Genotype-property patient-phenotype relations suggest that proteome exhaustion can cause amyotrophic lateral sclerosis.

PubMed

Kepp, Kasper P

2015-01-01

Late-onset neurodegenerative diseases remain poorly understood as search continues for the perceived pathogenic protein species. Previously, variants in Superoxide Dismutase 1 (SOD1) causing Amyotrophic Lateral Sclerosis (ALS) were found to destabilize and reduce net charge, suggesting a pathogenic aggregation mechanism. This paper reports analysis of compiled patient data and experimental and computed protein properties for variants of human SOD1, a major risk factor of ALS. Both stability and reduced net charge correlate significantly with disease, with larger significance than previously observed. Using two independent methods and two data sets, a probability < 3% (t-statistical test) is found that ALS-causing mutations share average stability with all possible 2907 SOD1 mutations. Most importantly, un-weighted patient survival times correlate strongly with the misfolded/unfolded protein copy number, expressed as an exponential function of the experimental stabilities (R2 = 0.31, p = 0.002), and this phenotype is further aggravated by charge (R2 = 0.51, p = 1.8 x 10-5). This finding suggests that disease relates to the copy number of misfolded proteins. Exhaustion of motor neurons due to expensive protein turnover of misfolded protein copies is consistent with the data but can further explain e.g. the expression-dependence of SOD1 pathogenicity, the lack of identification of a molecular toxic mode, elevated SOD1 mRNA levels in sporadic ALS, bioenergetic effects and increased resting energy expenditure in ALS patients, genetic risk factors affecting RNA metabolism, and recent findings that a SOD1 mutant becomes toxic when proteasome activity is recovered after washout of a proteasome inhibitor. Proteome exhaustion is also consistent with energy-producing mitochondria accumulating at the neuromuscular junctions where ALS often initiates. If true, this exhaustion mechanism implies a complete change of focus in treatment of ALS towards actively nursing the energy state and protein turnover of the motor neurons.

Formation and Stability of Microbially Derived Soil Organic Matter

NASA Astrophysics Data System (ADS)

Waldrop, M. P.; Creamer, C.; Foster, A. L.; Lawrence, C. R.; Mcfarland, J. W.; Schulz, M. S.

2017-12-01

Soil carbon is vital to soil health, food security, and climate change mitigation, but the underlying mechanisms controlling the stabilization and destabilization of soil carbon are still poorly understood. There has been a conceptual paradigm shift in how soil organic matter is formed which now emphasizes the importance of microbial activity to build stable (i.e. long-lived) and mineral-associated soil organic matter. In this conceptual model, the consumption of plant carbon by microorganisms, followed by subsequent turnover of microbial bodies closely associated with mineral particles, produces a layering of amino acid and lipid residues on the surfaces of soil minerals that remains protected from destabilization by mineral-association and aggregation processes. We tested this new model by examining how isotopically labeled plant and microbial C differ in their fundamental stabilization and destabilization processes on soil minerals through a soil profile. We used a combination of laboratory and field-based approaches to bridge multiple spatial scales, and used soil depth as well as synthetic minerals to create gradients of soil mineralogy. We used Raman microscopy as a tool to probe organic matter association with mineral surfaces, as it allows for the simultaneous quantification and identification of living microbes, carbon, minerals, and isotopes through time. As expected, we found that the type of minerals present had a strong influence on the amount of C retained, but the stabilization of new C critically depends on growth, death, and turnover of microbial cells. Additionally, the destabilization of microbial residue C on mineral surfaces was little affected by flushes of DOC relative to wet-dry cycles alone. We believe this new insight into microbial mechanisms of C stabilization in soils will eventually lead to new avenues for measuring and modeling SOM dynamics in soils, and aid in the management of soil C to mediate global challenges.

A Protein Aggregation Based Test for Screening of the Agents Affecting Thermostability of Proteins

PubMed Central

Eronina, Tatyana; Borzova, Vera; Maloletkina, Olga; Kleymenov, Sergey; Asryants, Regina; Markossian, Kira; Kurganov, Boris

2011-01-01

To search for agents affecting thermal stability of proteins, a test based on the registration of protein aggregation in the regime of heating with a constant rate was used. The initial parts of the dependences of the light scattering intensity (I) on temperature (T) were analyzed using the following empiric equation: I = K agg(T−T 0)2, where K agg is the parameter characterizing the initial rate of aggregation and T 0 is a temperature at which the initial increase in the light scattering intensity is registered. The aggregation data are interpreted in the frame of the model assuming the formation of the start aggregates at the initial stages of the aggregation process. Parameter T 0 corresponds to the moment of the origination of the start aggregates. The applicability of the proposed approach was demonstrated on the examples of thermal aggregation of glycogen phosphorylase b from rabbit skeletal muscles and bovine liver glutamate dehydrogenase studied in the presence of agents of different chemical nature. The elaborated approach to the study of protein aggregation may be used for rapid identification of small molecules that interact with protein targets. PMID:21760963

Validation of work pressure and associated factors influencing hospital nurse turnover: a cross-sectional investigation in Shaanxi Province, China.

PubMed

Yang, Huiyun; Lv, Jingwen; Zhou, Xi; Liu, Huitong; Mi, Baibing

2017-02-03

Nurses' turnover is a major contributor to nursing shortages, strongly influenced by nurses' intentions to leave. Several factors influencing the turnover intention have been well identified in Western countries and large cities in China. However, whether these factors also contribute to nurses' work stress in Midwest China are still unclear. The main purpose of this study was to examine the work pressure and associated factors influencing the nurses' intent to leave. A cross-sectional questionnaire-based survey with multistage sampling was conducted by recruiting 800 employed registered nurses with >1 year of work experience. Chi-square test and multi-factor logistic regression were applied to attain the relative comparisons. Sub-group analysis was conducted to explore the different turnover intention patterns in different age groups. The turnover intention was classified as strong/very-strong (19%), weak (62%), and very-weak (19%). Among the factors influencing the nurses' desire to leave the profession, work pressure was the most prominent. The predominantly associated factors contributing the work stress were age, experience, and workload. However, the scale of income did not affect the intent to leave decision. Pediatrics was identified to be the highest tormented department with a significant (P < 0.05) turnover of nurses. Among different age sub-groups, 30-39 age group nurses in Secondary hospitals demonstrate a stronger intent to leave. Nurses' turnover intentions were associated with stress, age, job duty, and career commitment in Shaanxi Province. The intent to leave is dynamically multifactorial, and effective managements and supportive strategies are needed to reduce the nurses work stress accordingly.

Cortactin as a Target for FAK in the Regulation of Focal Adhesion Dynamics

PubMed Central

Ghassemian, Majid; Schlaepfer, David D.

2012-01-01

Background Efficient cell movement requires the dynamic regulation of focal adhesion (FA) formation and turnover. FAs are integrin-associated sites of cell attachment and establish linkages to the cellular actin cytoskeleton. Cells without focal adhesion kinase (FAK), an integrin-activated tyrosine kinase, exhibit defects in FA turnover and cell motility. Cortactin is an actin binding adaptor protein that can influence FA dynamics. FAK and cortactin interact, but the cellular role of this complex remains unclear. Principal Findings Using FAK-null fibroblasts stably reconstituted with green fluorescent protein (GFP) tagged FAK constructs, we find that FAK activity and FAK C-terminal proline-rich region 2 (PRR2) and PRR3 are required for FA turnover and cell motility. Cortactin binds directly to FAK PRR2 and PRR3 sites via its SH3 domain and cortactin expression is important in promoting FA turnover and GFP-FAK release from FAs. FAK-cortactin binding is negatively-regulated by FAK activity and associated with cortactin tyrosine phosphorylation. FAK directly phosphorylates cortactin at Y421 and Y466 and over-expression of cortactin Y421, Y466, and Y482 mutated to phenylalanine (3YF) prevented FAK-enhanced FA turnover and cell motility. However, phospho-mimetic cortactin mutated to glutamic acid (3YE) did not affect FA dynamics and did not rescue FA turnover defects in cells with inhibited FAK activity or with PRR2-mutated FAK that does not bind cortactin. Conclusions Our results support a model whereby FAK-mediated FA remodeling may occur through the formation of a FAK-cortactin signaling complex. This involves a cycle of cortactin binding to FAK, cortactin tyrosine phosphorylation, and subsequent cortactin-FAK dissociation accompanied by FA turnover and cell movement. PMID:22952866

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

PubMed

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.

Modeling the effects of hypoxia on ATP turnover in exercising muscle

NASA Technical Reports Server (NTRS)

Arthur, P. G.; Hogan, M. C.; Bebout, D. E.; Wagner, P. D.; Hochachka, P. W.

1992-01-01

Most models of metabolic control concentrate on the regulation of ATP production and largely ignore the regulation of ATP demand. We describe a model, based on the results of Hogan et al. (J. Appl. Physiol. 73: 728-736, 1992), that incorporates the effects of ATP demand. The model is developed from the premise that a unique set of intracellular conditions can be measured at each level of ATP turnover and that this relationship is best described by energetic state. Current concepts suggest that cells are capable of maintaining oxygen consumption in the face of declines in the concentration of oxygen through compensatory changes in cellular metabolites. We show that these compensatory changes can cause significant declines in ATP demand and result in a decline in oxygen consumption and ATP turnover. Furthermore we find that hypoxia does not directly affect the rate of anaerobic ATP synthesis and associated lactate production. Rather, lactate production appears to be related to energetic state, whatever the PO2. The model is used to describe the interaction between ATP demand and ATP supply in determining final ATP turnover.

The effects of nursing turnover on continuity of care in isolated First Nation communities.

PubMed

Minore, Bruce; Boone, Margaret; Katt, Mae; Kinch, Peggy; Birch, Stephen; Mushquash, Christopher

2005-03-01

Many of Canada's northern First Nation communities experience difficulty recruiting and retaining appropriate nursing staff and must rely on relief nurses for short-term coverage. The latter often are not adequately prepared for the demanding nature of the practice. This study examined the consequences of nursing turnover on the continuity of care provided to residents of three Ojibway communities in northern Ontario. The findings are based on a review of 135 charts of oncology, diabetes, and mental health clients, and on interviews with 30 professional and paraprofessional health-care providers who served the communities. Nursing turnover is shown to detrimentally affect communications, medications management, and the range of services offered; it also results in compromised follow-up, client disengagement, illness exacerbation, and an added burden of care for family and community members.

National cultures, performance appraisal practices, and organizational absenteeism and turnover: a study across 21 countries.

PubMed

Peretz, Hilla; Fried, Yitzhak

2012-03-01

Performance appraisal (PA) is a key human resource activity in organizations. However, in this global economy, we know little about how societal cultures affect PA practices. In this study, we address this gap by focusing on 2 complementary issues: (a) the influence of societal (national) cultural practices on PA practices adopted by organizations and (b) the contribution of the level of congruence between societal cultural practices and the characteristics of organizational PA practices to absenteeism and turnover. The results, based on a large data set across multiple countries and over 2 time periods, support the hypothesized effects of societal (national) cultural practices on particular PA practices and the interactive effects of societal cultural practices and PA practices on absenteeism and turnover. We discuss theoretical and practical implications of our findings.

Diabetes, Biochemical Markers of Bone Turnover, Diabetes Control, and Bone

PubMed Central

Starup-Linde, Jakob

2012-01-01

Diabetes mellitus is known to have late complications including micro vascular and macro vascular disease. This review focuses on another possible area of complication regarding diabetes; bone. Diabetes may affect bone via bone structure, bone density, and biochemical markers of bone turnover. The aim of the present review is to examine in vivo from humans on biochemical markers of bone turnover in diabetics compared to non-diabetics. Furthermore, the effect of glycemic control on bone markers and the similarities and differences of type 1- and type 2-diabetics regarding bone markers will be evaluated. A systematic literature search was conducted using PubMed, Embase, Cinahl, and SveMed+ with the search terms: “Diabetes mellitus,” “Diabetes mellitus type 1,” “Insulin dependent diabetes mellitus,” “Diabetes mellitus type 2,” “Non-insulin dependent diabetes mellitus,” “Bone,” “Bone and Bones,” “Bone diseases,” “Bone turnover,” “Hemoglobin A Glycosylated,” and “HbA1C.” After removing duplicates from this search 1,188 records were screened by title and abstract and 75 records were assessed by full text for inclusion in the review. In the end 43 records were chosen. Bone formation and resorption markers are investigated as well as bone regulating systems. T1D is found to have lower osteocalcin and CTX, while osteocalcin and tartrate-resistant acid are found to be lower in T2D, and sclerostin is increased and collagen turnover markers altered. Other bone turnover markers do not seem to be altered in T1D or T2D. A major problem is the lack of histomorphometric studies in humans linking changes in turnover markers to actual changes in bone turnover and further research is needed to strengthen this link. PMID:23482417

Environmental Control on Microbial Turnover of Leaf Carbon in Streams – Ecological Function of Phototrophic-Heterotrophic Interactions

PubMed Central

Fabian, Jenny; Zlatanović, Sanja; Mutz, Michael; Grossart, Hans-Peter; van Geldern, Robert; Ulrich, Andreas; Gleixner, Gerd; Premke, Katrin

2018-01-01

In aquatic ecosystems, light availability can significantly influence microbial turnover of terrestrial organic matter through associated metabolic interactions between phototrophic and heterotrophic communities. However, particularly in streams, microbial functions vary significantly with the structure of the streambed, that is the distribution and spatial arrangement of sediment grains in the streambed. It is therefore essential to elucidate how environmental factors synergistically define the microbial turnover of terrestrial organic matter in order to better understand the ecological role of photo-heterotrophic interactions in stream ecosystem processes. In outdoor experimental streams, we examined how the structure of streambeds modifies the influence of light availability on microbial turnover of leaf carbon (C). Furthermore, we investigated whether the studied relationships of microbial leaf C turnover to environmental conditions are affected by flow intermittency commonly occurring in streams. We applied leaves enriched with a 13C-stable isotope tracer and combined quantitative and isotope analyses. We thereby elucidated whether treatment induced changes in C turnover were associated with altered use of leaf C within the microbial food web. Moreover, isotope analyses were combined with measurements of microbial community composition to determine whether changes in community function were associated with a change in community composition. In this study, we present evidence, that environmental factors interactively determine how phototrophs and heterotrophs contribute to leaf C turnover. Light availability promoted the utilization of leaf C within the microbial food web, which was likely associated with a promoted availability of highly bioavailable metabolites of phototrophic origin. However, our results additionally confirm that the structure of the streambed modifies light-related changes in microbial C turnover. From our observations, we conclude that the streambed structure influences the strength of photo-heterotrophic interactions by defining the spatial availability of algal metabolites in the streambed and the composition of microbial communities. Collectively, our multifactorial approach provides valuable insights into environmental controls on the functioning of stream ecosystems.

The Validity of the Three-Component Model of Organizational Commitment in a Chinese Context.

ERIC Educational Resources Information Center

Cheng, Yuqiu; Stockdale, Margaret S.

2003-01-01

The construct validity of a three-component model of organizational commitment was tested with 226 Chinese employees. Affective and normative commitment significantly predicted job satisfaction; all three components predicted turnover intention. Compared with Canadian (n=603) and South Korean (n=227) samples, normative and affective commitment…

Affective, Continuance, and Normative Commitment to the Organization: A Meta-analysis of Antecedents, Correlates, and Consequences.

ERIC Educational Resources Information Center

Meyer, John P.; Stanley, David J.; Herscovitch, Lynne; Topolnytsky, Laryssa

2002-01-01

Meta-analysis of 155 research reports that used one of three commitment scales (affective, continuance, or normative) found strong correlations between the scales and correlates of jobs satisfaction, job involvement, and organizational commitment. All three were negatively related to withdrawal and turnover. Perceived organizational support had…

How Negative Affectivity Moderates the Relationship between Shocks, Embeddedness and Worker Behaviors

ERIC Educational Resources Information Center

Holtom, Brooks C.; Burton, James P.; Crossley, Craig D.

2012-01-01

We integrated the unfolding model of turnover, job embeddedness theory and affective events theory to build and test a model specifying the relationship between negative shocks, on-the-job embeddedness and important employee behaviors. The results showed that embeddedness mediates the relationship between negative shocks and job search behaviors…

AGGREGATION PATHWAYS OF THE AMYLOID β(1–42) PEPTIDE DEPEND ON ITS COLLOIDAL STABILITY AND ORDERED β-SHEET STACKING

PubMed Central

Jiang, Dianlu; Rauda, Iris; Han, Shubo; Chen, Shu; Zhou, Feimeng

2012-01-01

Amyloid β (Aβ) fibrils are present as a major component in senile plaques, the hallmark of Alzheimer’s disease (AD). Diffuse plaques (non-fibrous, loosely packed Aβ aggregates) containing amorphous Aβ aggregates are also formed in brain. This work examines the influence of Cu2+ complexation by Aβ on the aggregation process in the context of charge and structural variations. Changes in the surface charges of Aβ molecules due to Cu2+ binding, measured with a zeta potential measurement device, were correlated with the aggregate morphologies examined by atomic force microscopy. As a result of the charge variation, the “colloid-like” stability of the aggregation intermediates, which is essential to the fibrillation process, is affected. Consequently Cu2+ enhances the amorphous aggregate formation. By monitoring variations in the secondary structures with circular dichroism spectroscopy, a direct transformation from the unstructured conformation to the β-sheet structure was observed for all types of aggregates observed (oligomers, fibrils, and/or amorphous aggregates). Compared to the Aβ aggregation pathway in the absence of Cu2+ and taking other factors affecting Aβ aggregation (i.e., pH and temperature) into account, our investigation indicates that formations of amorphous and fibrous aggregates diverge from the same β-sheet-containing partially folded intermediate. This study suggests that the hydrophilic domain of Aβ also plays a role in the Aβ aggregation process. A kinetic model was proposed to account for the effects of the Cu2+ binding on these two aggregation pathways in terms of charge and structural variations. PMID:22870885

N fertilization reduces the losses of old soil organic carbon

NASA Astrophysics Data System (ADS)

Zang, H.; Blagodatskaya, E.; Wang, J.; Kuzyakov, Y.; Xu, X.

2016-12-01

Agricultural soils have experiencing large anthropogenic nitrogen (N) inputs, which directly and indirectly affect soil organic matter (SOM) stocks and CO2 emissions. However, current understanding of how these additional N inputs affect SOM pools of various ages and turnover remains incomplete. The δ13C values of SOM after wheat (C3) - maize (C4) vegetation change enable to calculate the contribution of C4-derived rhizodeposited C (rhizo-C) and C3-derived old SOM pools. Soil (Ap from Haplic Luvisol) sampled from maize rhizosphere was incubated over 56 days after increasing N fertilization (4 levels up to 300 kg N ha-1). N fertilization decreased soil CO2 emissions by 27-42% as compared to unfertilized control. This decrease was mainly caused by the retardation of old C mineralization. The relative availability of rhizo-C (released by maize roots within 4 weeks) for microorganisms was about 10 times higher than of old C (older than 4 weeks). Microbial biomass and dissolved organic C were unaffected by increasing N. N fertilization, however, increased relative contribution of rhizo-C to microbial biomass for 2 - 5 times and to CO2 for about 2 times. This clearly reflects acceleration of microbial biomass turnover by N addition. The decomposition rate of rhizo-C was 3.7 times higher than of old C, and it increased additionally by the factor of 6.5 under high N fertilization. Our study is the first estimated the turnover and incorporation of very recent rhizo-C (within 4 weeks). Compared with several-years old C4, the turnover of rhizo-C was about 2 times faster. Concluding, the contribution of rhizo-C to CO2 and microbial biomass was highly responsive to N fertilization. N fertilization facilitates C sequestration in agricultural soils by decreasing old SOM decomposition mainly through increase the turnover and C use efficiency of rhizo-C. Keywords: CO2 partitioning; C3-C4 vegetation; microbial biomass; SOM decomposition; Nutrient availability

Assessing the effects of pharmacists' perceived organizational support, organizational commitment and turnover intention on provision of medication information at community pharmacies in Lithuania: a structural equation modeling approach.

PubMed

Urbonas, Gvidas; Kubilienė, Loreta; Kubilius, Raimondas; Urbonienė, Aušra

2015-03-01

As a member of a pharmacy organization, a pharmacist is not only bound to fulfill his/her professional obligations but is also affected by different personal and organizational factors that may influence his/her behavior and, consequently, the quality of the services he/she provides to patients. The main purpose of the research was to test a hypothesized model of the relationships among several organizational variables, and to investigate whether any of these variables affects the service of provision of medication information at community pharmacies. During the survey, pharmacists working at community pharmacies in Lithuania were asked to express their opinions on the community pharmacies at which they worked and to reflect on their actions when providing information on medicines to their patients. The statistical data were analyzed by applying a structural equation modeling technique to test the hypothesized model of the relationships among the variables of Perceived Organizational Support, Organizational Commitment, Turnover Intention, and Provision of Medication Information. The final model revealed that Organizational Commitment had a positive direct effect on Provision of Medication Information (standardized estimate = 0.27) and a negative direct effect (standardized estimate = -0.66) on Turnover Intention. Organizational Commitment mediated the indirect effects of Perceived Organizational Support on Turnover Intention (standardized estimate = -0.48) and on Provision of Medication Information (standardized estimate = 0.20). Pharmacists' Turnover Intention had no significant effect on Provision of Medication Information. Community pharmacies may be viewed as encouraging, to some extent, the service of provision of medication information. Pharmacists who felt higher levels of support from their organizations also expressed, to a certain extent, higher commitment to their organizations by providing more consistent medication information to patients. However, the effect of organizational variables on the variable of Provision of Medication Information appeared to be limited.

Stripping in hot mix asphalt produced by aggregates from construction and demolition waste.

PubMed

Pérez, I; Pasandín, A R; Gallego, J

2012-01-01

This paper analyses the effect of water on the durability of hot asphalt mixtures made with recycled aggregates from construction and demolition debris. Indirect tensile stress tests were carried out to evaluate stripping behaviour. The mixtures tested were fabricated with 0, 20, 40 and 60% recycled aggregates. Two types of natural aggregates were used: schist and calcite dolomite. An increase in the percentage of recycled aggregates was found to produce a decrease in the tensile stress ratio of the hot asphalt mixtures. To study this phenomenon, two and three factor analyses of variance (ANOVA) were performed with indirect tensile stress being used as the dependent variable. The factors studied were the percentage of recycled aggregates (0, 20, 40 and 60%), the moisture state (dry, wet) and the type of natural aggregate (schist, calcite). On the basis of the ANOVA results, it was found that the most important factor affecting resistance was the moisture state (dry, wet) of the specimens. The percentage of recycled aggregate also affected indirect tensile stress, especially in the dry state. The type of natural aggregate did not have a significant effect on indirect tensile stress. The hot asphalt mixture specimens made with different percentages of recycled aggregates from construction and demolition debris and of natural quarry aggregates showed poor stripping behaviour. This stripping behaviour can be related to both the poor adhesion of the recycled aggregates and the high absorption of the mortar of cement adhered to them.

Motivational pathways of occupational and organizational turnover intention among newly registered nurses in Canada.

PubMed

Fernet, Claude; Trépanier, Sarah-Geneviève; Demers, Mireille; Austin, Stéphanie

Staff turnover is a major issue for health care systems. In a time of labor shortage, it is critical to understand the motivational factors that underlie turnover intention in newly licensed nurses. To examine whether different forms of motivation (the reasons for which nurses engage in their work) predict intention to quit the occupation and organization through distinct forms (affective and continuance) and targets (occupation and organization) of commitment. Cross-sectional data were collected from a sample of 572 French-Canadian newly registered nurses working in public health care in the province of Quebec, Canada. The hypothesized model was tested by structural equation modeling. Autonomous motivation (nurses accomplish their work primarily out of a sense of pleasure and satisfaction or because they personally endorse the importance or value of their work) negatively predicts intention to quit the profession and organization through target-specific affective commitment. However, although controlled motivation (nurses accomplish their work mainly because of internal or external pressure) is positively associated with continuance commitment to the occupation and organization, it directly predicts, positively so, intention to quit the occupation and organization. These results highlight the complexity of the motivational processes at play in the turnover intention of novice nurses, revealing distinct forms of commitment that explain how motivation quality is related simultaneously to intention to quit the occupation and organization. Health care organizations are advised to promote autonomous over controlled motivation to retain newly recruited nurses and sustain the future of the nursing workforce. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

The effect of increased air humidity on fine root and rhizome biomass and turnover of silver birch forest ecosystem - a FAHM study.

NASA Astrophysics Data System (ADS)

Ostonen, I.; Kupper, P.; Sõber, J.; Aosaar, J.; Varik, M.; Lõhmus, K.

2012-04-01

A facility for free air humidity manipulation (FAHM) was established to investigate the effect of increased air humidity on belowground biomass and turnover in silver birch (Betula pendula Roth.) forest ecosystems with respect to rising air humidity predicted for Northern Europe. Fine root and rhizomes are short-lived and recognized as the most important component contributing to below-ground C fluxes in forests. The FAHM system enables air relative humidity to be increased on average 7 units (%) over the ambient level during mist fumigation. The experimental site contains humidified (H) and control (C) plots; each plot contains sectors with diverse "forest" understory and early successional grasses. The trees were planted in 2006, humidification started in spring 2008, and soil cores to study fine root and rhizome biomass and turnover were taken in 2007, 2009 and 2010. In July 2009, total fine root and rhizome biomass was 8 tons per ha in C and 16 tons per ha in H plots. The roots of understory formed 86% in C and 93% H plots, respectively. Our preliminary data suggest that the increased humidity affected more the roots of understory plants: fine root and rhizome biomass and production increased approximately twice by increasing air humidity. However, the tendency was similar for fine root biomass and production of silver birch. Fine root turnover speeded up for both silver birch and understory roots in H plots. Hence, changes in air humidity can significantly affect forest carbon cycling.

Heterogeneous glycation of cancellous bone and its association with bone quality and fragility.

PubMed

Karim, Lamya; Vashishth, Deepak

2012-01-01

Non-enzymatic glycation (NEG) and enzymatic biochemical processes create crosslinks that modify the extracellular matrix (ECM) and affect the turnover of bone tissue. Because NEG affects turnover and turnover at the local level affects microarchitecture and formation and removal of microdamage, we hypothesized that NEG in cancellous bone is heterogeneous and accounts partly for the contribution of microarchitecture and microdamage on bone fragility. Human trabecular bone cores from 23 donors were subjected to compression tests. Mechanically tested cores as well as an additional 19 cores were stained with lead-uranyl acetate and imaged to determine microarchitecture and measure microdamage. Post-yield mechanical properties were measured and damaged trabeculae were extracted from a subset of specimens and characterized for the morphology of induced microdamage. Tested specimens and extracted trabeculae were quantified for enzymatic and non-enzymatic crosslink content using a colorimetric assay and Ultra-high Performance Liquid Chromatography (UPLC). Results show that an increase in enzymatic crosslinks was beneficial for bone where they were associated with increased toughness and decreased microdamage. Conversely, bone with increased NEG required less strain to reach failure and were less tough. NEG heterogeneously modified trabecular microarchitecture where high amounts of NEG crosslinks were found in trabecular rods and with the mechanically deleterious form of microdamage (linear microcracks). The extent of NEG in tibial cancellous bone was the dominant predictor of bone fragility and was associated with changes in microarchitecture and microdamage.

Heterogeneous Glycation of Cancellous Bone and Its Association with Bone Quality and Fragility

PubMed Central

Karim, Lamya; Vashishth, Deepak

2012-01-01

Non-enzymatic glycation (NEG) and enzymatic biochemical processes create crosslinks that modify the extracellular matrix (ECM) and affect the turnover of bone tissue. Because NEG affects turnover and turnover at the local level affects microarchitecture and formation and removal of microdamage, we hypothesized that NEG in cancellous bone is heterogeneous and accounts partly for the contribution of microarchitecture and microdamage on bone fragility. Human trabecular bone cores from 23 donors were subjected to compression tests. Mechanically tested cores as well as an additional 19 cores were stained with lead-uranyl acetate and imaged to determine microarchitecture and measure microdamage. Post-yield mechanical properties were measured and damaged trabeculae were extracted from a subset of specimens and characterized for the morphology of induced microdamage. Tested specimens and extracted trabeculae were quantified for enzymatic and non-enzymatic crosslink content using a colorimetric assay and Ultra-high Performance Liquid Chromatography (UPLC). Results show that an increase in enzymatic crosslinks was beneficial for bone where they were associated with increased toughness and decreased microdamage. Conversely, bone with increased NEG required less strain to reach failure and were less tough. NEG heterogeneously modified trabecular microarchitecture where high amounts of NEG crosslinks were found in trabecular rods and with the mechanically deleterious form of microdamage (linear microcracks). The extent of NEG in tibial cancellous bone was the dominant predictor of bone fragility and was associated with changes in microarchitecture and microdamage. PMID:22514706

N-terminal acetylation -an Essential Protein Modification Emerges as an Important Regulator of Stress Responses.

PubMed

Linster, Eric; Wirtz, Markus

2018-06-26

N-terminal acetylation (NTA) is a prevalent protein modification in eukaryotes. The majority of proteins is acetylated at their N-terminus in a co-translational manner by ribosome-associated N-terminal acetyltransferases (NAT). However, the recent discovery of Golgi-membrane localized NATs in metazoan, and plastid-localized NATs in plants challenged the dogma of static, co-translational imprinting of the proteome by NTA. Indeed, NTA by the cytosolic NatA is highly dynamic and under hormonal control in plants. Such active control has not been evidenced yet in other eukaryotes and might be an adaptation to the sessile lifestyle of plants forcing them to cope with diverse environmental challenges. The function of NTA for individual proteins is distinct and yet unpredictable. In yeast and humans, NTA has been shown to affect protein-protein interactions, subcellular localization, folding, aggregation, or degradation of a handful of proteins. In particular, the impact of NTA on the protein-turnover is documented by diverse examples in yeast. Consequently, NTA has recently dicovered to be a degradation signal in a distinct branch of the N-end rule pathway ubiquitin-mediated proteolysis. In this review, we summarize the current knowledge on the NAT machinery in higher plants and discuss the potential function of NTA during biotic and abiotic stresses.

Effect of epimedium pubescen flavonoid on bone mineral status and bone turnover in male rats chronically exposed to cigarette smoke

PubMed Central

2012-01-01

Background Epimedii herba is one of the most frequently used herbs in formulas that are prescribed for the treatment of osteoporosis in China and its main constituent is Epimedium pubescen flavonoid (EPF). However, it is unclear whether EPF during chronic exposure to cigarette smoke may have a protective influence on the skeleton. The present study investigated the effect of EPF on bone mineral status and bone turnover in a rat model of human relatively high exposure to cigarette smoke. Methods Fifty male Wistar rats were randomized into five groups: controls, passive smoking groups and passive smoking rats administered EPF at three dosage levels (75, 150 or 300 mg/kg/day) in drinking water for 4 months. A rat model of passive smoking was prepared by breeding male rats in a cigarette-smoking box. Bone mineral content (BMC), bone mineral density (BMD), bone turnover markers, bone histomorphometric parameters and biomechanical properties were examined. Results Smoke exposure decreased BMC and BMD, increased bone turnover (inhibited bone formation and stimulated its resorption), affected bone histomorphometry (increased trabecular separation and osteoclast surface per bone surface; decreased trabecular bone volume, trabecular thickness, trabecular number, cortical thickness, bone formation rate and osteoblast surface per bone surface), and reduced mechanical properties. EPF supplementation during cigarette smoke exposure prevented smoke-induced changes in bone mineral status and bone turnover. Conclusion The results suggest that EPF can prevent the adverse effects of smoke exposure on bone by stimulating bone formation and inhibiting bone turnover and bone resorption. PMID:22713117

Effect of epimedium pubescen flavonoid on bone mineral status and bone turnover in male rats chronically exposed to cigarette smoke.

PubMed

Gao, Shu-guang; Cheng, Ling; Li, Kang-hua; Liu, Wen-He; Xu, Mai; Jiang, Wei; Wei, Li-Cheng; Zhang, Fang-jie; Xiao, Wen-feng; Xiong, Yi-lin; Tian, Jian; Zeng, Chao; Sun, Jin-peng; Xie, Qiang; Lei, Guang-hua

2012-06-19

Epimedii herba is one of the most frequently used herbs in formulas that are prescribed for the treatment of osteoporosis in China and its main constituent is Epimedium pubescen flavonoid (EPF). However, it is unclear whether EPF during chronic exposure to cigarette smoke may have a protective influence on the skeleton. The present study investigated the effect of EPF on bone mineral status and bone turnover in a rat model of human relatively high exposure to cigarette smoke. Fifty male Wistar rats were randomized into five groups: controls, passive smoking groups and passive smoking rats administered EPF at three dosage levels (75, 150 or 300 mg/kg/day) in drinking water for 4 months. A rat model of passive smoking was prepared by breeding male rats in a cigarette-smoking box. Bone mineral content (BMC), bone mineral density (BMD), bone turnover markers, bone histomorphometric parameters and biomechanical properties were examined. Smoke exposure decreased BMC and BMD, increased bone turnover (inhibited bone formation and stimulated its resorption), affected bone histomorphometry (increased trabecular separation and osteoclast surface per bone surface; decreased trabecular bone volume, trabecular thickness, trabecular number, cortical thickness, bone formation rate and osteoblast surface per bone surface), and reduced mechanical properties. EPF supplementation during cigarette smoke exposure prevented smoke-induced changes in bone mineral status and bone turnover. The results suggest that EPF can prevent the adverse effects of smoke exposure on bone by stimulating bone formation and inhibiting bone turnover and bone resorption.

Employee retention: an issue of survival in healthcare.

PubMed

Collins, Sandra K; Collins, Kevin S

2004-01-01

Successful healthcare organizations emphasize attracting human resource assets and aggressively seek to resolve and prevent high employee turnover. Understanding the key components surrounding the importance of measuring employee turnover, learning how it affects patient care, and realizing what is needed to retain quality employees is central to the resolution. Measuring employee turnover in a healthcare department is fundamental to the success of the organization and the quality of care it delivers. Some studies indicate the cost of turnover can average 150% of the employee's annual salary. Furthermore, when employees leave, their duties are shifted to the remaining personnel who feel obligated to shoulder the additional burden. The most important impact of employee turnover may be the effect on patient care. Generally, all patients prefer to be cared for by the same members of a healthcare team each time they require treatment. This involves building relationships between the patients and their respective healthcare organizations. These relationships are important to the success of the facility, especially in cases where the same treatment/care can be received elsewhere. Creating an organizational environment that is dedicated to the retention of talented personnel is the first step in reducing employee turnover. Determining why employees are leaving an organization is an important part of developing an effective strategy. One way this information can be obtained is by conducting detailed exit interviews. Organizations should focus on the following issues in order to maintain their qualified workforce in the long term: communication; decision making; compensation, benefits, and career development; recruitment; appreciation and understanding; and management.

Effect of cocoa products and flavanols on platelet aggregation in humans: a systematic review.

PubMed

Peluso, Ilaria; Palmery, Maura; Serafini, Mauro

2015-07-01

Previous evidence suggested an active role of cocoa products and flavanols in modulating platelet aggregation. However, cocoa flavanols are characterized by a low bioavailability that can deeply affect their presence in biological fluids and raise questions on their biological effect in humans. We performed a systematic search on Medline, Embase, Cochrane and ProQuest databases, until April 2015, on the effect of cocoa products on platelet aggregation in human intervention studies. We identified 13 interventions, of which only five involved repeated administration. Different effects were observed on the basis of the platelet aggregation test used, whereas neither a longer duration of treatment nor a higher dose was associated with a higher inhibition of platelet aggregation. In conclusion, the reviewed results suggest that consumption of cocoa products in bolus administration positively affects platelet aggregation in both healthy subjects and diseased patients. On the other hand, more evidence is required in order to assess the effect of long-term cocoa product ingestion and to identify the bioactive components involved.

7 CFR 51.1564 - External defects.

Code of Federal Regulations, 2013 CFR

2013-01-01

... than 50 percent of the surface in the aggregate. Growth Cracks When the growth crack(s) affects more... Table V.) When the growth crack(s) affects more than 3/4 the length of the potato in the aggregate or.... Second Growth When materially detracting from the appearance of the potato When seriously detracting from...

7 CFR 51.1564 - External defects.

Code of Federal Regulations, 2014 CFR

2014-01-01

... than 50 percent of the surface in the aggregate. Growth Cracks When the growth crack(s) affects more... Table V.) When the growth crack(s) affects more than 3/4 the length of the potato in the aggregate or.... Second Growth When materially detracting from the appearance of the potato When seriously detracting from...

7 CFR 51.1414 - Serious damage.

Code of Federal Regulations, 2010 CFR

2010-01-01

... as serious damage: (a) Adhering hull material or dark stains affecting an aggregate of more than 20...) Decay affecting any portion of the kernel; (g) Insect injury when the insect, web or frass is present... than three dark spots on either half of the kernel, or when any spot or the aggregate of two or more...

7 CFR 51.1414 - Serious damage.

Code of Federal Regulations, 2011 CFR

2011-01-01

... as serious damage: (a) Adhering hull material or dark stains affecting an aggregate of more than 20...) Decay affecting any portion of the kernel; (g) Insect injury when the insect, web or frass is present... than three dark spots on either half of the kernel, or when any spot or the aggregate of two or more...

7 CFR 51.1414 - Serious damage.

Code of Federal Regulations, 2012 CFR

2012-01-01

... as serious damage: (a) Adhering hull material or dark stains affecting an aggregate of more than 20...) Decay affecting any portion of the kernel; (g) Insect injury when the insect, web or frass is present... than three dark spots on either half of the kernel, or when any spot or the aggregate of two or more...

Synaptic Remodeling in the Dentate Gyrus, CA3, CA1, Subiculum, and Entorhinal Cortex of Mice: Effects of Deprived Rearing and Voluntary Running

PubMed Central

Schaefers, Andrea T. U.; Grafen, Keren; Teuchert-Noodt, Gertraud; Winter, York

2010-01-01

Hippocampal cell proliferation is strongly increased and synaptic turnover decreased after rearing under social and physical deprivation in gerbils (Meriones unguiculatus). We examined if a similar epigenetic effect of rearing environment on adult neuroplastic responses can be found in mice (Mus musculus). We examined synaptic turnover rates in the dentate gyrus, CA3, CA1, subiculum, and entorhinal cortex. No direct effects of deprived rearing on rates of synaptic turnover were found in any of the studied regions. However, adult wheel running had the effect of leveling layer-specific differences in synaptic remodeling in the dentate gyrus, CA3, and CA1, but not in the entorhinal cortex and subiculum of animals of both rearing treatments. Epigenetic effects during juvenile development affected adult neural plasticity in mice, but seemed to be less pronounced than in gerbils. PMID:20508828

The impact of sexual harassment on job satisfaction, turnover intentions, and absenteeism: findings from Pakistan compared to the United States.

PubMed

Merkin, Rebecca S; Shah, Muhammad Kamal

2014-01-01

The purpose of this study was to compare and contrast how differences in perceptions of sexual harassment impact productive work environments for employees in Pakistan as compared to the US; in particular, how it affects job satisfaction, turnover, and/or absenteeism. This study analyzed employee responses in Pakistan (n = 146) and the United States (n = 102, 76) using questionnaire data. Significant results indicated that employees who were sexually harassed reported (a) a decrease in job satisfaction (b) greater turnover intentions and (c) a higher rate of absenteeism. Cross-cultural comparisons indicated that (a) Pakistani employees who were sexually harassed had greater job dissatisfaction and higher overall absenteeism than did their US counterparts and (b) Pakistani women were more likely to use indirect strategies to manage sexual harassment than were US targets.

Antecedents of Student Teachers' Affective Commitment to the Teaching Profession and Turnover Intention

ERIC Educational Resources Information Center

Christophersen, Knut-Andreas; Elstad, Eyvind; Solhaug, Trond; Turmo, Are

2016-01-01

Several European countries have experienced both a dearth of and reduction in the quality of applicants to teacher education study programmes. There is also significant leakage from these programmes. The rationale for this study therefore lies in the need to reduce teacher attrition. Research indicates that affective commitment to a profession is…

Water level changes affect carbon turnover and microbial community composition in lake sediments

Treesearch

Lukas Weise; Andreas Ulrich; Matilde Moreano; Arthur Gessler; Zachary E. Kayler; Kristin Steger; Bernd Zeller; Kristin Rudolph; Jelena Knezevic-Jaric

2016-01-01

Due to climate change, many lakes in Europe will be subject to higher variability of hydrological characteristics in their littoral zones. These different hydrological regimes might affect the use of allochthonous and autochthonous carbon sources. We used sandy sediment microcosms to examine the effects of different hydrological regimes (wet, desiccating, and wet-...

An Assessment of Meyer and Allen's (1991) Three-Component Model of Organizational Commitment and Turnover Intentions.

ERIC Educational Resources Information Center

Jaros, Stephen J.

1997-01-01

Data from 158 part-time graduate students employed full time and 160 aerospace engineers were used to test a model of organizational commitment. Contrary to expectations, the three components of commitment (affective, normative, continuance) differed in their effects on intention to quit. Affective commitment had a significantly stronger…

Large-scale experimental landscapes reveal distinctive effects of patch shape and connectivity on arthropod communities.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orrock, John, L.; Curler, Gregory, R.; Danielson, Brent, J.

2011-09-14

The size, shape, and isolation of habitat patches can affect organism behavior and population dynamics, but little is known about the relative role of shape and connectivity in affecting ecological communities at large spatial scales. Using six sampling sessions from July 2001 until August 2002, we collected 33,685 arthropods throughout seven 12-ha experimental landscapes consisting of clear-cut patches surrounded by a matrix of mature pine forest. Patches were explicitly designed to manipulate connectivity (via habitat corridors) independently of area and edge effects. We found that patch shape, rather than connectivity, affected ground-dwelling arthropod richness and beta diversity (i.e. turnover ofmore » genera among patches). Arthropod communities contained fewer genera and exhibited less turnover in high-edge connected and high-edge unconnected patches relative to low-edge unconnected patches of similar area. Connectivity, rather than patch shape, affected the evenness of ground-dwelling arthropod communities; regardless of patch shape, high-edge connected patches had lower evenness than low- or high-edge unconnected patches. Among the most abundant arthropod orders, increased richness in low-edge unconnected patches was largely due to increased richness of Coleoptera, whereas Hymenoptera played an important role in the lower evenness in connected patches and patterns of turnover. These findings suggest that anthropogenic habitat alteration can have distinct effects on ground-dwelling arthropod communities that arise due to changes in shape and connectivity. Moreover, this work suggests that corridors, which are common conservation tools that change both patch shape and connectivity, can have multiple effects on arthropod communities via different mechanisms, and each effect may alter components of community structure.« less

Erythrocyte deformability and aggregation responses to intermittent and continuous artificial gravity exposure

NASA Astrophysics Data System (ADS)

Marijke, Grau; Vera, Abeln; Tobias, Vogt; Wilhelm, Bloch; Stefan, Schneider

2017-02-01

Artificial gravity protocols are used to improve g-tolerance of aviators and discussed as countermeasure during prolonged space flight. Little is known about the impact of artificial gravity on the red blood cells (RBC). The purpose of the study was to test how artificial gravity affects RBC deformability and aggregation, which are important determinants of microcirculation. Nine male subjects were exposed to two hypergravity protocols using a short arm human centrifuge: a continuous (CONT) protocol with constant +2 Gz for 30 min and an intermittent (INTER) protocol with repeated intervals of +2 Gz and rest. Blood was sampled pre and post interventions to measure basal blood parameters, RBC nitrite, RBC deformability, aggregation, and to determine the shear rate balancing aggregation and disaggregation (γ at dIsc min). To test for orthostasis effects, five male subjects were asked to stay for 46 min, corresponding to the length of the centrifuge protocols, with blood sampling pre and post intervention. Artificial gravity programs did not affect basal blood parameters or RBC nitrite levels; a marker for RBC deformability influencing nitric oxide. The INTER program did not affect any of the tested parameters. The CONT program did not remarkably affect RBC deformability or γ at dIsc min but significantly aggravated aggregation. Orthostasis effects were thus excluded. The results indicate that continuous artificial gravity, especially with higher g-forces applied, may negatively affect the RBC system and that for a prolonged space flight intermittent but not continuous artificial gravity might represent an appropriate countermeasure.

Long-Range Regulatory Polymorphisms Affecting a GABA Receptor Constitute a Quantitative Trait Locus (QTL) for Social Behavior in Caenorhabditis elegans

PubMed Central

Bendesky, Andres; Pitts, Jason; Rockman, Matthew V.; Chen, William C.; Tan, Man-Wah; Kruglyak, Leonid; Bargmann, Cornelia I.

2012-01-01

Aggregation is a social behavior that varies between and within species, providing a model to study the genetic basis of behavioral diversity. In the nematode Caenorhabditis elegans, aggregation is regulated by environmental context and by two neuromodulatory pathways, one dependent on the neuropeptide receptor NPR-1 and one dependent on the TGF-β family protein DAF-7. To gain further insight into the genetic regulation of aggregation, we characterize natural variation underlying behavioral differences between two wild-type C. elegans strains, N2 and CB4856. Using quantitative genetic techniques, including a survey of chromosome substitution strains and QTL analysis of recombinant inbred lines, we identify three new QTLs affecting aggregation in addition to the two known N2 mutations in npr-1 and glb-5. Fine-mapping with near-isogenic lines localized one QTL, accounting for 5%–8% of the behavioral variance between N2 and CB4856, 3′ to the transcript of the GABA neurotransmitter receptor gene exp-1. Quantitative complementation tests demonstrated that this QTL affects exp-1, identifying exp-1 and GABA signaling as new regulators of aggregation. exp-1 interacts genetically with the daf-7 TGF-β pathway, which integrates food availability and population density, and exp-1 mutations affect the level of daf-7 expression. Our results add to growing evidence that genetic variation affecting neurotransmitter receptor genes is a source of natural behavioral variation. PMID:23284308

Inhalation of Whole Diesel Exhaust but not Gas-Phase Components Affects In Vitro Platelet Aggregation in Hypertensive Rats

EPA Science Inventory

Rationale: Intravascular thrombosis and platelet aggregation are enhanced following exposure to diesel exhaust (DE) and other respirable particulate matter; however, the roles of endothelial and circulating mediators on platelet aggregation remain unclear. We hypothesized that ad...

Aggregate Stability of Tropical Soils Under Long-Term Eucalyptus Cultivation

USDA-ARS?s Scientific Manuscript database

Eucalyptus cultivation has increased in all Brazilian regions. Despite the large amount of cultivated area, little is known about how this kind of management system affects soil properties, mainly the aggregate stability. Aggregate stability analyses have proved to be a sensitive tool to measure soi...

Matrix metalloproteinases in acute coronary syndromes: current perspectives.

PubMed

Kampoli, Anna-Maria; Tousoulis, Dimitris; Papageorgiou, Nikolaos; Antoniades, Charalambos; Androulakis, Emmanuel; Tsiamis, Eleftherios; Latsios, George; Stefanadis, Christodoulos

2012-01-01

Matrix metalloproteinases (MMPs) are a family of zinc metallo-endopeptidases secreted by cells and are responsible for much of the turnover of matrix components. Several studies have shown that MMPs are involved in all stages of the atherosclerotic process, from the initial lesion to plaque rupture. Recent evidence suggests that MMP activity may facilitate atherosclerosis, plaque destabilization, and platelet aggregation. In the heart, matrix metalloproteinases participate in vascular remodeling, plaque instability, and ventricular remodelling after cardiac injury. The aim of the present article is to review the structure, function, regulation of MMPs and to discuss their potential role in the pathogenesis of acute coronary syndromes, as well as their contribution and usefullness in the setting of the disease.

Data on industrial new orders for the euro area.

PubMed

de Bondt, Gabe J; Dieden, Heinz C; Muzikarova, Sona; Pavlova, Iskra

2016-12-01

This data article provides time series on euro area industrial new orders and is related to the research article entitled "Modelling industrial new orders" (G.J. de Bondt, H.C. Dieden, S. Muzikarova, I. Vincze, 2014b) [3]. The data are in index format with a fixed base year (currently 2010) for total new orders as well as a number of breakdowns. The euro area data are based on the official national data for countries that still collect data and on European Central Bank (ECB) model estimates for countries that discontinued the data collection. The weighting scheme to calculate euro area aggregates makes use of country weights derived from industrial turnover statistics as published by Eurostat.

A New Insight to Bone Turnover: Role of ω-3 Polyunsaturated Fatty Acids

PubMed Central

López-Frías, Magdalena; López-Aliaga, Inmaculada; Ochoa, Julio J.

2013-01-01

Background. Evidence has shown that long-chain polyunsaturated fatty acids (LCPUFA), especially the ω-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are beneficial for bone health and turnover. Objectives. This review summarizes findings from both in vivo and in vitro studies and the effects of LC PUFA on bone metabolism, as well as the relationship with the oxidative stress, the inflammatory process, and obesity. Results. Some studies in humans indicate that LCPUFA can increase bone formation, affect peak bone mass in adolescents, and reduce bone loss. However, the cellular mechanisms of action of the LCPUFA are complex and involve modulation of fatty acid metabolites such as prostaglandins, resolvins and protectins, several signaling pathways, cytokines, and growth factors, although in certain aspects there is still some controversy. LCPUFA affect receptor activator of nuclear factor κ β (RANK), a receptor found on the osteoclast, causing bone resorption, which controls osteoclast formation. Conclusions. Since fatty acids are an endogenous source of reactive oxygen species, free radicals alter the process of bone turnover; however, although there are clinical evidences linking bone metabolism and dietary lipids, more clinical trials are necessary to prove whether ω-3 PUFA supplementation plays a major role in bone health. PMID:24302863

Aggregates from natural and recycled sources; economic assessments for construction applications; a materials flow study

USGS Publications Warehouse

Wilburn, David R.; Goonan, Thomas G.

1998-01-01

Increased amounts of recycled materials are being used to supplement natural aggregates (derived from crushed stone, sand and gravel) in road construction. An understanding of the economics and factors affecting the level of aggregates recycling is useful in estimating the potential for recycling and in assessing the total supply picture of aggregates. This investigation includes a descriptive analysis of the supply sources, technology, costs, incentives, deterrents, and market relationships associated with the production of aggregates.

Influence of the Nursing Practice Environment on Job Satisfaction and Turnover Intention

PubMed Central

Lee, Sang-Yi; Kim, Chul-Woung; Kang, Jeong-Hee; Yoon, Tae-Ho; Kim, Cheoul Sin

2014-01-01

Objectives: To examine whether the nursing practice environment at the hospital-level affects the job satisfaction and turnover intention of hospital nurses. Methods: Among the 11 731 nurses who participated in the Korea Health and Medical Workers’ Union’s educational program, 5654 responded to our survey. Data from 3096 nurses working in 185 general inpatient wards at 60 hospitals were analyzed using multilevel logistic regression modeling. Results: Having a standardized nursing process (odds ratio [OR], 4.21; p<0.001), adequate nurse staffing (OR, 4.21; p<0.01), and good doctor-nurse relationship (OR, 4.15; p<0.01), which are hospital-level variables based on the Korean General Inpatients Unit Nursing Work Index (KGU-NWI), were significantly related to nurses’ job satisfaction. However, no hospital-level variable from the KGU-NWI was significantly related to nurses’ turnover intention. Conclusions: Favorable nursing practice environments are associated with job satisfaction among nurses. In particular, having a standardized nursing process, adequate nurse staffing, and good doctor-nurse relationship were found to positively influence nurses’ job satisfaction. However, the nursing practice environment was not related to nurses’ turnover intention. PMID:25284197

[Medical and entrepreneurial character of the community pharmacy].

PubMed

Malovecká, Ivona; Minarovič, Igor; Mináriková, Daniela; Snopková, Miroslava; Lehocká, Lubica; Foltán, Viliam

2014-04-01

Community pharmacy provides citizens with pharmaceutical care and runs its health care business on the market with state regulatory interventions. These restrictions affect its stability and because of that it has to be constantly monitored. The convenient way of monitoring the financial health of a community pharmacy is the use of financial analysis and its outcomes that are profitability, liquidity, debt and productivity ratios. The aim of this paper was to determine the economic situation in the public pharmacy services in Slovakia. A representative set of community pharmacies was established that reflected the criteria of localization by regions in Slovakia, the size of the city or municipality and the legal form of the subject. The financial analysis for the years 2007-2012 showed a declining return on sales (in 2012 to 1.98 %), a decreasing current liquidity (in 2012 to 1.87 %), a declining quick ratio (in 2012 to 1.08 %), a decrease in the time receivables turnover (in 2012 to 53.8 days), a slight increase in the inventory turnover time - days sales in inventory (in 2012 to 36.5 days) and increased turnover time commitments - liabilities turnover (in 2012 to 86.3 days). community pharmacy financial health profitability liquidity productivity.

Numerical investigation of aggregated fuel spatial pattern impacts on fire behavior

DOE PAGES

Parsons, Russell A.; Linn, Rodman Ray; Pimont, Francois; ...

2017-06-18

Here, landscape heterogeneity shapes species distributions, interactions, and fluctuations. Historically, in dry forest ecosystems, low canopy cover and heterogeneous fuel patterns often moderated disturbances like fire. Over the last century, however, increases in canopy cover and more homogeneous patterns have contributed to altered fire regimes with higher fire severity. Fire management strategies emphasize increasing within-stand heterogeneity with aggregated fuel patterns to alter potential fire behavior. Yet, little is known about how such patterns may affect fire behavior, or how sensitive fire behavior changes from fuel patterns are to winds and canopy cover. Here, we used a physics-based fire behavior model,more » FIRETEC, to explore the impacts of spatially aggregated fuel patterns on the mean and variability of stand-level fire behavior, and to test sensitivity of these effects to wind and canopy cover. Qualitative and quantitative approaches suggest that spatial fuel patterns can significantly affect fire behavior. Based on our results we propose three hypotheses: (1) aggregated spatial fuel patterns primarily affect fire behavior by increasing variability; (2) this variability should increase with spatial scale of aggregation; and (3) fire behavior sensitivity to spatial pattern effects should be more pronounced under moderate wind and fuel conditions.« less

Numerical investigation of aggregated fuel spatial pattern impacts on fire behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsons, Russell A.; Linn, Rodman Ray; Pimont, Francois

Here, landscape heterogeneity shapes species distributions, interactions, and fluctuations. Historically, in dry forest ecosystems, low canopy cover and heterogeneous fuel patterns often moderated disturbances like fire. Over the last century, however, increases in canopy cover and more homogeneous patterns have contributed to altered fire regimes with higher fire severity. Fire management strategies emphasize increasing within-stand heterogeneity with aggregated fuel patterns to alter potential fire behavior. Yet, little is known about how such patterns may affect fire behavior, or how sensitive fire behavior changes from fuel patterns are to winds and canopy cover. Here, we used a physics-based fire behavior model,more » FIRETEC, to explore the impacts of spatially aggregated fuel patterns on the mean and variability of stand-level fire behavior, and to test sensitivity of these effects to wind and canopy cover. Qualitative and quantitative approaches suggest that spatial fuel patterns can significantly affect fire behavior. Based on our results we propose three hypotheses: (1) aggregated spatial fuel patterns primarily affect fire behavior by increasing variability; (2) this variability should increase with spatial scale of aggregation; and (3) fire behavior sensitivity to spatial pattern effects should be more pronounced under moderate wind and fuel conditions.« less

Age-related collagen turnover of the interstitial matrix and basement membrane: Implications of age- and sex-dependent remodeling of the extracellular matrix.

PubMed

Kehlet, Stephanie N; Willumsen, Nicholas; Armbrecht, Gabriele; Dietzel, Roswitha; Brix, Susanne; Henriksen, Kim; Karsdal, Morten A

2018-01-01

The extracellular matrix (ECM) plays a vital role in maintaining normal tissue function. Collagens are major components of the ECM and there is a tight equilibrium between degradation and formation of these proteins ensuring tissue health and homeostasis. As a consequence of tissue turnover, small collagen fragments are released into the circulation, which act as important biomarkers in the study of certain tissue-related remodeling factors in health and disease. The aim of this study was to establish an age-related collagen turnover profile of the main collagens of the interstitial matrix (type I and III collagen) and basement membrane (type IV collagen) in healthy men and women. By using well-characterized competitive ELISA-assays, we assessed specific fragments of degraded (C1M, C3M, C4M) and formed (PINP, Pro-C3, P4NP7S) type I, III and IV collagen in serum from 617 healthy men and women ranging in ages from 22 to 86. Subjects were divided into 5-year age groups according to their sex and age. Groups were compared using Kruskal-Wallis adjusted for Dunn's multiple comparisons test and Mann-Whitney t-test. Age-specific changes in collagen turnover was most profound for type I collagen. PINP levels decreased in men with advancing age, whereas in women, the level decreased in early adulthood followed by an increase around the age of menopause (age 40-60). Sex-specific changes in type I, III and IV collagen turnover was present at the age around menopause (age 40-60) with women having an increased turnover. In summary, collagen turnover is affected by age and sex with the interstitial matrix and the basement membrane being differently regulated. The observed changes needs to be accounted for when measuring ECM related biomarkers in clinical studies.

Relationships between soil microbial communities and soil carbon turnover along a vegetation and moisture gradient in interior Alaska

NASA Astrophysics Data System (ADS)

Waldrop, M. P.; Harden, J. W.; Turetsky, M. R.; Petersen, D. G.; McGuire, A. D.; Briones, M. J.; Churchill, A. C.; Doctor, D. H.; Pruett, L. E.

2010-12-01

Boreal landscapes are characterized by a mosaic of uplands and lowlands, which differ in plant species composition, litter biochemistry, and biogeochemical cycling rates. Boreal ecosystems, from upland black spruce stands to lowland fens, are structured largely by water table position and contain quantitatively and qualitatively different forms of soil organic matter. Differences in carbon (C) availability among ecosystems likely translate to differences in the structure of soil microbial communities, which in turn could affect rates of organic matter decomposition and turnover. We examined relationships between microbial communities and soil C turnover in near-surface soils along a topographic soil moisture and vegetation gradient in interior Alaska. We tested the hypothesis that upland black spruce sites would be dominated by soil fungi and have slow rates of C turnover, whereas lowland ecosystems would be dominated by bacteria and mesofauna (enchytraeids) and have more rapid rates of C turnover. We utilized several isotopic measures of soil C turnover including bomb radiocarbon techniques, the δ15N of SOM, and the difference between δ13C of SOM, DOC, and respired CO2. All three measures indicated greater C turnover rates in the surface soils of the lowland fen sites compared to the more upland locations. Quantitative PCR analyses of soil bacteria and archaea, combined with enchytraed counts, confirmed that surface soils from the lowland fen ecosystems had the highest abundances of these functional groups. Fungal biomass was highly variable and tended to be more abundant in the upland forest sites. Soil enzymatic results were mixed: potential cellulase activities were higher in the more upland soils even though rates of microbial activity were generally lower. Oxidative enzyme activities were higher in fens, even though these ecosystems are saturated and partly anaerobic. Overall our data support soil food web theory which argues that rapidly cycling systems are bacterial dominated with mesofaunal grazing, whereas slowly cycling systems have characteristic higher fungal:bacterial ratios.

Projected climate impacts for the amphibians of the western hemisphere

USGS Publications Warehouse

Lawler, Joshua J.; Shafer, Sarah L.; Bancroft, Betsy A.; Blaustein, Andrew R.

2010-01-01

Given their physiological requirements, limited dispersal abilities, and hydrologically sensitive habitats, amphibians are likely to be highly sensitive to future climatic changes. We used three approaches to map areas in the western hemisphere where amphibians are particularly likely to be affected by climate change. First, we used bioclimatic models to project potential climate-driven shifts in the distribution of 413 amphibian species based on 20 climate simulations for 2071–2100. We summarized these projections to produce estimates of species turnover. Second, we mapped the distribution of 1099 species with restricted geographic ranges. Finally, using the 20 future climate-change simulations, we mapped areas that were consistently projected to receive less seasonal precipitation in the coming century and thus were likely to have altered microclimates and local hydrologies. Species turnover was projected to be highest in the Andes Mountains and parts of Central America and Mexico, where, on average, turnover rates exceeded 60% under the lower of two emissions scenarios. Many of the restricted-range species not included in our range-shift analyses were concentrated in parts of the Andes and Central America and in Brazil's Atlantic Forest. Much of Central America, southwestern North America, and parts of South America were consistently projected to experience decreased precipitation by the end of the century. Combining the results of the three analyses highlighted several areas in which amphibians are likely to be significantly affected by climate change for multiple reasons. Portions of southern Central America were simultaneously projected to experience high species turnover, have many additional restricted-range species, and were consistently projected to receive less precipitation. Together, our three analyses form one potential assessment of the geographic vulnerability of amphibians to climate change and as such provide broad-scale guidance for directing conservation efforts.

No differential effects of divergent isocaloric supplements on signaling for muscle protein turnover during recovery from muscle-damaging eccentric exercise.

PubMed

Rahbek, Stine Klejs; Farup, Jean; de Paoli, Frank; Vissing, Kristian

2015-04-01

Unaccustomed high-intensity eccentric exercise (ECC) can provoke muscle damage including several days of muscle force loss. Post-exercise dietary supplementation may provide a strategy to accelerate rate of force regain by affecting mechanisms related to muscle protein turnover. The aim of the current study was to investigate if protein signaling mechanisms involved in muscle protein turnover would be differentially affected by supplementation with either whey protein hydrolysate and carbohydrate (WPH+CHO) versus isocaloric carbohydrate (CHO) after muscle-damaging ECC. Twenty-four young healthy participants received either WPH+CHO (n = 12) or CHO supplements (n = 12) during post-exercise recovery from 150 maximal unilateral eccentric contractions. Prior to, at 3 h and at 24, 48, 96 and/or 168 h post-exercise, muscle strength, muscle soreness, and Akt-mTOR and FOXO signaling proteins, were measured in an ECC exercising leg and in the contralateral non-exercise control leg (CON). After ECC, muscle force decreased by 23-27 % at 24 h post-exercise, which was followed by gradual, although not full recovery at 168 h post-exercise, with no differences between supplement groups. Phosphorylation of mTOR, p70S6K and rpS6 increased and phosphorylation of FOXO1 and FOXO3 decreased in the ECC leg, with no differences between supplement groups. Phosphorylation changes were also observed for rpS6, FOXO1 and FOXO3a in the CON leg, suggesting occurrence of remote tissue effects. In conclusion, divergent dietary supplementation types did not produce differences in signaling for muscle turnover during recovery from muscle-damaging exercise.

Projected climate impacts for the amphibians of the Western hemisphere.

PubMed

Lawler, Joshua J; Shafer, Sarah L; Bancroft, Betsy A; Blaustein, Andrew R

2010-02-01

Given their physiological requirements, limited dispersal abilities, and hydrologically sensitive habitats, amphibians are likely to be highly sensitive to future climatic changes. We used three approaches to map areas in the western hemisphere where amphibians are particularly likely to be affected by climate change. First, we used bioclimatic models to project potential climate-driven shifts in the distribution of 413 amphibian species based on 20 climate simulations for 2071-2100. We summarized these projections to produce estimates of species turnover. Second, we mapped the distribution of 1099 species with restricted geographic ranges. Finally, using the 20 future climate-change simulations, we mapped areas that were consistently projected to receive less seasonal precipitation in the coming century and thus were likely to have altered microclimates and local hydrologies. Species turnover was projected to be highest in the Andes Mountains and parts of Central America and Mexico, where, on average, turnover rates exceeded 60% under the lower of two emissions scenarios. Many of the restricted-range species not included in our range-shift analyses were concentrated in parts of the Andes and Central America and in Brazil's Atlantic Forest. Much of Central America, southwestern North America, and parts of South America were consistently projected to experience decreased precipitation by the end of the century. Combining the results of the three analyses highlighted several areas in which amphibians are likely to be significantly affected by climate change for multiple reasons. Portions of southern Central America were simultaneously projected to experience high species turnover, have many additional restricted-range species, and were consistently projected to receive less precipitation. Together, our three analyses form one potential assessment of the geographic vulnerability of amphibians to climate change and as such provide broad-scale guidance for directing conservation efforts.

Implication of alcohol consumption on aggregate wellbeing.

PubMed

Parackal, Mathew; Parackal, Sherly

2017-07-01

The effects of drinking alcohol extend beyond the individuals concerned to the wider community. While there is recognition of such a global implication, currently no study has quantified the impact of alcohol consumption on aggregate wellbeing. This study aims to address this gap and attempts to investigate the impact of various levels of alcohol consumption on aggregate happiness. The study was carried out on a random selection of participants ( n = 1,817) drawn from the 3Di consumer panel, comprising over 170,000 New Zealanders aged 18 and above. Using a subjective happiness scale (SHS) in conjunction with the Alcohol Use Disorders Identification Test (AUDIT), investigation was carried out to find whether drinking behaviour affected aggregate happiness. SHS and AUDIT scores were negatively correlated and the strength of the correlation increased with the intensity of problematic drinking. Regression analysis showed that the beta coefficient was positive for the low-risk (.074) and negative for the high-risk (-.081) category, suggesting approaches to intervene with the growing problem of alcohol consumption in modern societies. Measurements of happiness can explain the global implication of alcohol in wellbeing terms. The findings of this study indicated that low-risk drinkers affected aggregate happiness positively, whereas high-risk drinkers affected aggregate happiness negatively. While the latter observation is not new, the former raises the need to promote moderation in drinking alcohol for the common good of everyone.

The Properties of Mortar Mixtures Blended with Natural, Crushed, and Recycled Fine Aggregates for Building Construction Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Myoung-Youl; Lee, Jae-Yong; Chung, Chul-Woo

2012-01-12

In this research, the possible applicability of fine aggregates blended with natural, crushed, and recycled fine aggregate are discussed. The fresh and hardened properties of mortar using blended fine aggregates are monitored depending on various blending ratio of fine aggregates. Newly developed ternary diagram was also utilized for better interpretation of the data. It was found that air content increased and unit weight decreased as recycled fine aggregate content increased. With moisture type processing of recycled fine aggregate, the mortar flow was not negatively affected by increase in the recycled fine aggregate content. The ternary diagram is found to bemore » an effective graphical presentation tool that can be used for the quality evaluation of mortar using blended fine aggregate.« less

Heating of Porous Icy Dust Aggregates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirono, Sin-iti

At the beginning of planetary formation, highly porous dust aggregates are formed through coagulation of dust grains. Outside the snowline, the main component of an aggregate is H{sub 2}O ice. Because H{sub 2}O ice is formed in amorphous form, its thermal conductivity is extremely small. Therefore, the thermal conductivity of an icy dust aggregate is low. There is a possibility of heating inside an aggregate owing to the decay of radionuclides. It is shown that the temperature increases substantially inside an aggregate, leading to crystallization of amorphous ice. During the crystallization, the temperature further increases sufficiently to continue sintering. Themore » mechanical properties of icy dust aggregates change, and the collisional evolution of dust aggregates is affected by the sintering.« less

Limited protection of macro-aggregate-occluded organic carbon in Siberian steppe soils

NASA Astrophysics Data System (ADS)

Bischoff, Norbert; Mikutta, Robert; Shibistova, Olga; Puzanov, Alexander; Silanteva, Marina; Grebennikova, Anna; Fuß, Roland; Guggenberger, Georg

2017-05-01

Macro-aggregates especially in agricultural steppe soils are supposed to play a vital role for soil organic carbon (OC) stabilization at a decadal timescale. While most research on soil OC stabilization in steppes focused on North American prairie soils of the Great Plains with information mainly provided by short-term incubation experiments, little is known about the agricultural steppes in southwestern Siberia, though they belong to the greatest conversion areas in the world and occupy an area larger than that in the Great Plains. To quantify the proportion of macro-aggregate-protected OC under different land use as function of land use intensity and time since land use change (LUC) from pasture to arable land in Siberian steppe soils, we determined OC mineralization rates of intact (250-2000 µm) and crushed (< 250 µm) macro-aggregates in long-term incubations over 401 days (20 °C; 60 % water holding capacity) along two agricultural chronosequences in the Siberian Kulunda steppe. Additionally, we incubated bulk soil (< 2000 µm) to determine the effect of LUC and subsequent agricultural use on a fast and a slow soil OC pool (labile vs. more stable OC), as derived from fitting exponential-decay models to incubation data. We hypothesized that (i) macro-aggregate crushing leads to increased OC mineralization due to an increasing microbial accessibility of a previously occluded labile macro-aggregate OC fraction, and (ii) bulk soil OC mineralization rates and the size of the fast OC pool are higher in pasture than in arable soils with decreasing bulk soil OC mineralization rates and size of the fast OC pool as land use intensity and time since LUC increase. Against our hypothesis, OC mineralization rates of crushed macro-aggregates were similar to those of intact macro-aggregates under all land use regimes. Macro-aggregate-protected OC was almost absent and accounted for < 1 % of the total macro-aggregate OC content and to a maximum of 8 ± 4 % of mineralized OC. In accordance to our second hypothesis, highest bulk soil OC mineralization rates and sizes of the fast OC pool were determined under pasture, but mineralization rates and pool sizes were unaffected by land use intensity and time since LUC. However, at one chronosequence mean residence times of the fast and slow OC pool tended to decrease with increasing time since establishment of arable use. We conclude that the tillage-induced breakdown of macro-aggregates has not reduced the OC contents in the soils under study. The decline of OC after LUC is probably attributed to the faster soil OC turnover under arable land as compared to pasture at a reduced plant residue input.

Effect of aggregate graining compositions on skid resistance of Exposed Aggregate Concrete pavement

NASA Astrophysics Data System (ADS)

Wasilewska, Marta; Gardziejczyk, Wladysław; Gierasimiuk, Pawel

2018-05-01

The paper presents the evaluation of skid resistance of EAC (Exposed Aggregate Concrete) pavements which differ in aggregate graining compositions. The tests were carried out on concrete mixes with a maximum aggregate size of 8 mm. Three types of coarse aggregates were selected depending on their resistance to polishing which was determined on the basis of the PSV (Polished Stone Value). Basalt (PSV 48), gabbro (PSV 50) and trachybasalt (PSV 52) aggregates were chosen. For each type of aggregate three graining compositions were designed, which differed in the content of coarse aggregate > 4mm. Their content for each series was as follows: A - 38%, B - 50% and C - 68%. Evaluation of the skid resistance has been performed using the FAP (Friction After Polishing) test equipment also known as the Wehner/Schulze machine. Laboratory method enables to compare the skid resistance of different types of wearing course under specified conditions simulating polishing processes. In addition, macrotexture measurements were made on the surface of each specimen using the Elatexure laser profile. Analysis of variance showed that at significance level α = 0.05, aggregate graining compositions as well as the PSV have a significant influence on the obtained values of the friction coefficient μm of the tested EAC pavements. The highest values of the μm have been obtained for EAC with the lowest amount of coarse aggregates (compositions A). In these cases the resistance to polishing of the aggregate does not significantly affect the friction coefficients. This is related to the large areas of cement mortar between the exposed coarse grains. Based on the analysis of microscope images, it was observed that the coarse aggregates were not sufficiently exposed. It has been proved that PSV significantly affected the coefficient of friction in the case of compositions B and C. This is caused by large areas of exposed coarse aggregate. The best parameters were achieved for the EAC pavements with graining composition B and C and trachybasalt aggregate.

A Two-Dimensional Numerical Investigation of Transport of Malaria-Infected Red Blood Cells in Stenotic Microchannels

PubMed Central

Tao, Yong; Rongin, Uwitije; Xing, Zhongwen

2016-01-01

The malaria-infected red blood cells experience a significant decrease in cell deformability and increase in cell membrane adhesion. Blood hemodynamics in microvessels is significantly affected by the alteration of the mechanical property as well as the aggregation of parasitized red blood cells. In this study, we aim to numerically study the connection between cell-level mechanobiological properties of human red blood cells and related malaria disease state by investigating the transport of multiple red blood cell aggregates passing through microchannels with symmetric stenosis. Effects of stenosis magnitude, aggregation strength, and cell deformability on cell rheology and flow characteristics were studied by a two-dimensional model using the fictitious domain-immersed boundary method. The results indicated that the motion and dissociation of red blood cell aggregates were influenced by these factors and the flow resistance increases with the increase of aggregating strength and cell stiffness. Further, the roughness of the velocity profile was enhanced by cell aggregation, which considerably affected the blood flow characteristics. The study may assist us in understanding cellular-level mechanisms in disease development. PMID:28105411

Soy proteins and isoflavones affect bone mineral density in older women: a randomized controlled trial.

PubMed

Kenny, Anne M; Mangano, Kelsey M; Abourizk, Robin H; Bruno, Richard S; Anamani, Denise E; Kleppinger, Alison; Walsh, Stephen J; Prestwood, Karen M; Kerstetter, Jane E

2009-07-01

Soy foods contain several components (isoflavones and amino acids) that potentially affect bone. Few long-term, large clinical trials of soy as a means of improving bone mineral density (BMD) in late postmenopausal women have been conducted. Our goal was to evaluate the long-term effect of dietary soy protein and/or soy isoflavone consumption on skeletal health in late postmenopausal women. We conducted a randomized, double-blind, placebo-controlled clinical trial in 131 healthy ambulatory women aged >60 y. Ninety-seven women completed the trial. After a 1-mo baseline period, subjects were randomly assigned into 1 of 4 intervention groups: soy protein (18 g) + isoflavone tablets (105 mg isoflavone aglycone equivalents), soy protein + placebo tablets, control protein + isoflavone tablets, and control protein + placebo tablets. Consumption of protein powder and isoflavone pills did not differ between groups, and compliance with the study powder and pills was 80-90%. No significant differences in BMD were observed between groups from baseline to 1 y after the intervention or in BMD change between equol and non-equol producers. However, there were significant negative correlations between total dietary protein (per kg) and markers of bone turnover (P < 0.05). Because soy protein and isoflavones (either alone or together) did not affect BMD, they should not be considered as effective interventions for preserving skeletal health in older women. The negative correlation between dietary protein and bone turnover suggests that increasing protein intakes may suppress skeletal turnover. This trial was registered at ClinicalTrials.gov as NCT00668447.

Retaining Staff Employees: The Relationship between Human Resources Management Strategies and Organizational Commitment.

ERIC Educational Resources Information Center

Buck, Jeffrey M.; Watson, John L.

2002-01-01

Explored whether an institution's human resources management (HRM) strategies can influence individuals' organizational commitment levels, which ultimately can affect staff turnover rates. Found significant relationship between certain HRM strategies and commitment constructs. (EV)

Association between amino acid turnover and chromosome aneuploidy during human preimplantation embryo development in vitro

PubMed Central

Picton, Helen M.; Elder, Kay; Houghton, Franchesca D.; Hawkhead, Judith A.; Rutherford, Anthony J.; Hogg, Jan E.; Leese, Henry J.; Harris, Sarah E.

2010-01-01

This study investigated the relationship between human preimplantation embryo metabolism and aneuploidy rates during development in vitro. One hundred and eighty-eight fresh and cryopreserved embryos from 59 patients (33.9 ± 0.6 years) were cultured for 2–5 days. The turnover of 18 amino acids was measured in spent media by high-performance liquid chromatography. Embryos were either fixed for interphase fluorescent in situ hybridization analysis of chromosomes 13, 18, 19, 21, X or Y, or were assayed for mitochondrial activity. Amino acid turnover was different (P < 0.05) between stage-matched fresh and cryopreserved embryos due to blastomere loss following warming. The proportion of embryos with aneuploid cells increased as cell division progressed from pronucleate- (23%) to late cleavage stages (50–70%). Asparagine, glycine and valine turnover was significantly different between uniformly genetically normal and uniformly abnormal embryos on Days 2–3 of culture. By Days 3–4, the profiles of serine, leucine and lysine differed between uniformly euploid versus aneuploid embryos. Gender significantly (P < 0.05) affected the metabolism of tryptophan, leucine and asparagine by cleavage-stage embryos. Pronucleate zygotes had a significantly higher proportion of active:inactive mitochondria compared with cleavage-stage embryos. Furthermore, mitochondrial activity was correlated (P < 0.05) with altered aspartate and glutamine turnover. These results demonstrate the association between the metabolism, cytogenetic composition and health of human embryos in vitro. PMID:20571076

Nurses' turnover intention: The impact of leader-member exchange, organizational identification and job embeddedness.

PubMed

Dechawatanapaisal, Decha

2018-06-01

The aim of this study was to examine the influence of three factors on turnover intention: leader-member exchange quality, organizational identification and job embeddedness. This area of inquiry has not been fully investigated in the literature. Employee turnover, particularly of professionals, becomes a very challenging issue. It continually affects organizations in terms of resourcing and developmental costs, manpower instability, day-to-day operations, perception of quality care and efficiency. Therefore, employees' working attitude and behaviour have drawn increasing attention for further research to determine which factors keep them with their employer. A cross-sectional survey was conducted with self-report questionnaires. Data were collected from 1,966 nurses from sixteen private general hospitals in Thailand during February-June 2016. Hypotheses were tested and analysed by means of a confirmatory factor analysis, structural equation modelling and a bootstrapping procedure. The results revealed the direct relationship between leader-member exchange quality and job embeddedness. Organizational identification played an intermediary role that partially mediated the relationship between leader-member exchange quality on job embeddedness. Analysis also provided support for the mediating effect of organizational identification and turnover intention through job embeddedness. This study extends the job embeddedness theory and gains understanding of the antecedent factors that directly and indirectly cause employees to become embedded and lead to predict turnover intention. The findings are pertinent, as few studies have investigated such relationships. The implications provide insights into how organizations can better retain their workforce. © 2018 John Wiley & Sons Ltd.

The role of brain extracellular proteins in neuroplasticity and learning.

PubMed

Shashoua, V E

1985-06-01

Double labeling studies of the pattern of protein synthesis in goldfish and mouse brain identified a class of glycoproteins (the ependymins) whose turnover rate was enhanced after training. A variety of control experiments indicated that these macromolecules have an important role in the molecular and cell biology of learning. Antisera to the ependymins when injected into the brains of trained goldfish cause amnesia of a newly acquired behavior. Isolation and localization studies by immunocytochemical methods indicate that the ependymins are released into the brain extracellular fluid by a class of neurosecretory cells. In mammalian brain ependymin-containing cells are highly concentrated in the limibic system. The ependymins are constituted from two disulfide-linked acidic polypeptide chains (M.W.37K and 31K). They contain at least 5% covalently bound carbohydrate per chain with mannose, galactose, N-acetylglucosamine and N-acetylneuraminic acid as the predominant components. The highly soluble ependymins can rapidly polymerize to form an insoluble fibrous matrix if calcium is removed from solution by the addition of a Ca2+-chelating agent or dialysis. The self-aggregation property of the ependymins can be triggered by the depletion of Ca2+ from the extracellular space. Studies of the kinetics of the aggregation phenomenon by measurements of turbidity changes indicate that the process can be terminated but not reversed by restoring Ca2+ to its normal CSF level. Immunohistochemical studies of the brains of trained goldfish show the presence of punctate statining sites in the perimeter of certain cells located in specific brain regions. This suggests that ependymin aggregation might occur in vivo during learning. A molecular hypothesis relating the aggregation properties of the ependymins to neuroplasticity and learning is proposed.

Differential Function of N-Cadherin and Cadherin-7 in the Control of Embryonic Cell Motility

PubMed Central

Dufour, Sylvie; Beauvais-Jouneau, Alice; Delouvée, Annie; Thiery, Jean Paul

1999-01-01

Similar amounts of N-cadherin and cadherin-7, the prototypes of type I and type II cadherin, induced cell-cell adhesion in murine sarcoma 180 transfectants, Ncad-1 and cad7-29, respectively. However, in the initial phase of aggregation, Ncad-1 cells aggregated more rapidly than cad7-29 cells. Isolated Ncad-1 and cad7-29 cells adhered and spread in a similar manner on fibronectin (FN), whereas aggregated cad7-29 cells were more motile and dispersed than aggregated Ncad-1 cells. cad7-29 cells established transient contacts with their neighbors which were stabilized if FN-cell interactions were perturbed. In contrast, Ncad-1 cells remained in close contact when they migrated on FN. Both β-catenin and cadherin were more rapidly downregulated in cad7-29 than in Ncad-1 cells treated with cycloheximide, suggesting a higher turnover rate for cadherin-7–mediated cell-cell contacts than for those mediated by N-cadherin. The extent of FN-dependent focal adhesion kinase phosphorylation was much lower if the cells had initiated N-cadherin–mediated rather than cadherin-7–mediated cell adhesion before plating. On grafting into the embryo, Ncad-1 cells did not migrate and remained at or close to the graft site, even after 48 h, whereas grafted cad7-29 cells dispersed efficiently into embryonic structures. Thus, the adhesive phenotype of cadherin-7–expressing cells is regulated by the nature of the extracellular matrix environment which also controls the migratory behavior of the cells. In addition, adhesions mediated by different cadherins differentially regulate FN-dependent signaling. The transient contacts specifically observed in cadherin- 7–expressing cells may also be important in the control of cell motility. PMID:10427101

Getting off on the right foot: subjective value versus economic value in predicting longitudinal job outcomes from job offer negotiations.

PubMed

Curhan, Jared R; Elfenbein, Hillary Anger; Kilduff, Gavin J

2009-03-01

Although negotiation experiences can affect a negotiator's ensuing attitudes and behavior, little is known about their long-term consequences. Using a longitudinal survey design, the authors tested the degree to which economic and subjective value achieved in job offer negotiations predicts employees' subsequent job attitudes and intentions concerning turnover. Results indicate that subjective value predicts greater compensation satisfaction and job satisfaction and lower turnover intention measured 1 year later. Surprisingly, the economic outcomes that negotiators achieved had no apparent effects on these factors. Implications, limitations, and future directions are discussed. (c) 2009 APA, all rights reserved.

Activity-driven changes in the mechanical properties of fire ant aggregations

NASA Astrophysics Data System (ADS)

Tennenbaum, Michael; Fernandez-Nieves, Alberto

2017-11-01

Fire ant aggregations are active materials composed of individual constituents that are able to transform internal energy into work. We find using rheology and direct visualization that the aggregation undergoes activity cycles that affect the mechanical properties of the system. When the activity is high, the aggregation approximately equally stores and dissipates energy, it is more homogeneous, and exerts a high outward force. When the activity is low, the aggregation is predominantly elastic, it is more heterogeneous, and it exerts a small outward force. We rationalize our results using a simple kinetic model where the number of active ants within the aggregation is the essential quantity.

Regulation of aggregate size and pattern by adenosine and caffeine in cellular slime molds

PubMed Central

2012-01-01

Background Multicellularity in cellular slime molds is achieved by aggregation of several hundreds to thousands of cells. In the model slime mold Dictyostelium discoideum, adenosine is known to increase the aggregate size and its antagonist caffeine reduces the aggregate size. However, it is not clear if the actions of adenosine and caffeine are evolutionarily conserved among other slime molds known to use structurally unrelated chemoattractants. We have examined how the known factors affecting aggregate size are modulated by adenosine and caffeine. Result Adenosine and caffeine induced the formation of large and small aggregates respectively, in evolutionarily distinct slime molds known to use diverse chemoattractants for their aggregation. Due to its genetic tractability, we chose D. discoideum to further investigate the factors affecting aggregate size. The changes in aggregate size are caused by the effect of the compounds on several parameters such as cell number and size, cell-cell adhesion, cAMP signal relay and cell counting mechanisms. While some of the effects of these two compounds are opposite to each other, interestingly, both compounds increase the intracellular glucose level and strengthen cell-cell adhesion. These compounds also inhibit the synthesis of cAMP phosphodiesterase (PdsA), weakening the relay of extracellular cAMP signal. Adenosine as well as caffeine rescue mutants impaired in stream formation (pde4- and pdiA-) and colony size (smlA- and ctnA-) and restore their parental aggregate size. Conclusion Adenosine increased the cell division timings thereby making large number of cells available for aggregation and also it marginally increased the cell size contributing to large aggregate size. Reduced cell division rates and decreased cell size in the presence of caffeine makes the aggregates smaller than controls. Both the compounds altered the speed of the chemotactic amoebae causing a variation in aggregate size. Our data strongly suggests that cytosolic glucose and extracellular cAMP levels are the other major determinants regulating aggregate size and pattern. Importantly, the aggregation process is conserved among different lineages of cellular slime molds despite using unrelated signalling molecules for aggregation. PMID:22269093

Regulation of aggregate size and pattern by adenosine and caffeine in cellular slime molds.

PubMed

Jaiswal, Pundrik; Soldati, Thierry; Thewes, Sascha; Baskar, Ramamurthy

2012-01-23

Multicellularity in cellular slime molds is achieved by aggregation of several hundreds to thousands of cells. In the model slime mold Dictyostelium discoideum, adenosine is known to increase the aggregate size and its antagonist caffeine reduces the aggregate size. However, it is not clear if the actions of adenosine and caffeine are evolutionarily conserved among other slime molds known to use structurally unrelated chemoattractants. We have examined how the known factors affecting aggregate size are modulated by adenosine and caffeine. Adenosine and caffeine induced the formation of large and small aggregates respectively, in evolutionarily distinct slime molds known to use diverse chemoattractants for their aggregation. Due to its genetic tractability, we chose D. discoideum to further investigate the factors affecting aggregate size. The changes in aggregate size are caused by the effect of the compounds on several parameters such as cell number and size, cell-cell adhesion, cAMP signal relay and cell counting mechanisms. While some of the effects of these two compounds are opposite to each other, interestingly, both compounds increase the intracellular glucose level and strengthen cell-cell adhesion. These compounds also inhibit the synthesis of cAMP phosphodiesterase (PdsA), weakening the relay of extracellular cAMP signal. Adenosine as well as caffeine rescue mutants impaired in stream formation (pde4- and pdiA-) and colony size (smlA- and ctnA-) and restore their parental aggregate size. Adenosine increased the cell division timings thereby making large number of cells available for aggregation and also it marginally increased the cell size contributing to large aggregate size. Reduced cell division rates and decreased cell size in the presence of caffeine makes the aggregates smaller than controls. Both the compounds altered the speed of the chemotactic amoebae causing a variation in aggregate size. Our data strongly suggests that cytosolic glucose and extracellular cAMP levels are the other major determinants regulating aggregate size and pattern. Importantly, the aggregation process is conserved among different lineages of cellular slime molds despite using unrelated signalling molecules for aggregation.

Fibril polymorphism affects immobilized non-amyloid flanking domains of huntingtin exon1 rather than its polyglutamine core

PubMed Central

Lin, Hsiang-Kai; Boatz, Jennifer C.; Krabbendam, Inge E.; Kodali, Ravindra; Hou, Zhipeng; Wetzel, Ronald; Dolga, Amalia M.; Poirier, Michelle A.; van der Wel, Patrick C. A.

2017-01-01

Polyglutamine expansion in the huntingtin protein is the primary genetic cause of Huntington's disease (HD). Fragments coinciding with mutant huntingtin exon1 aggregate in vivo and induce HD-like pathology in mouse models. The resulting aggregates can have different structures that affect their biochemical behaviour and cytotoxic activity. Here we report our studies of the structure and functional characteristics of multiple mutant htt exon1 fibrils by complementary techniques, including infrared and solid-state NMR spectroscopies. Magic-angle-spinning NMR reveals that fibrillar exon1 has a partly mobile α-helix in its aggregation-accelerating N terminus, and semi-rigid polyproline II helices in the proline-rich flanking domain (PRD). The polyglutamine-proximal portions of these domains are immobilized and clustered, limiting access to aggregation-modulating antibodies. The polymorphic fibrils differ in their flanking domains rather than the polyglutamine amyloid structure. They are effective at seeding polyglutamine aggregation and exhibit cytotoxic effects when applied to neuronal cells. PMID:28537272

Fibril polymorphism affects immobilized non-amyloid flanking domains of huntingtin exon1 rather than its polyglutamine core

NASA Astrophysics Data System (ADS)

Lin, Hsiang-Kai; Boatz, Jennifer C.; Krabbendam, Inge E.; Kodali, Ravindra; Hou, Zhipeng; Wetzel, Ronald; Dolga, Amalia M.; Poirier, Michelle A.; van der Wel, Patrick C. A.

2017-05-01

Polyglutamine expansion in the huntingtin protein is the primary genetic cause of Huntington's disease (HD). Fragments coinciding with mutant huntingtin exon1 aggregate in vivo and induce HD-like pathology in mouse models. The resulting aggregates can have different structures that affect their biochemical behaviour and cytotoxic activity. Here we report our studies of the structure and functional characteristics of multiple mutant htt exon1 fibrils by complementary techniques, including infrared and solid-state NMR spectroscopies. Magic-angle-spinning NMR reveals that fibrillar exon1 has a partly mobile α-helix in its aggregation-accelerating N terminus, and semi-rigid polyproline II helices in the proline-rich flanking domain (PRD). The polyglutamine-proximal portions of these domains are immobilized and clustered, limiting access to aggregation-modulating antibodies. The polymorphic fibrils differ in their flanking domains rather than the polyglutamine amyloid structure. They are effective at seeding polyglutamine aggregation and exhibit cytotoxic effects when applied to neuronal cells.

Dietary protein level and source differentially affect bone metabolism, strength, and intestinal calcium transporter expression during ad libitum and food-restricted conditions in male rats

USDA-ARS?s Scientific Manuscript database

High protein diets may attenuate bone loss during energy restriction (ER). The objective of the current study was to determine whether high protein diets suppress bone turnover and improve bone quality in rats during ER and whether dietary protein source affects this relationship. Eighty 12-week o...

Monetary Policy Rules, Supply Shocks, and the Price-Level Elasticity of Aggregate Demand: A Graphical Examination.

ERIC Educational Resources Information Center

Kyer, Ben L.; Maggs, Gary E.

1995-01-01

Utilizes two-dimensional price and output graphs to demonstrate the way that the price-level elasticity of aggregate demand affects alternative monetary policy rules designed to cope with random aggregate supply shocks. Includes graphs illustrating price-level, real Gross Domestic Product (GDP), nominal GDP, and nominal money supply targeting.…

Platelet aggregation caused by Carybdea rastonii toxins (CrTX-I, II and III) obtained from a jellyfish, Carybdea rastonii.

PubMed

Azuma, H; Sekizaki, S; Satoh, A; Nakajima, T

1986-05-01

The pharmacological mechanisms of platelet aggregation induced by highly toxic proteins (CrTX-I, CrTX-II, and CrTX-III) obtained from tentacles of a jellyfish, Carybdea rastonii, were investigated. When the partially purified toxin (pCrTX) and CrTXs were added to the citrated platelet-rich plasma (PRP), aggregation was produced in a concentration-dependent manner. The activity of CrTXs was approximately 100 times more potent than pCrTX. The CrTXs-induced aggregation was little affected by indomethacin and quinacrine at concentrations sufficient to inhibit arachidonic acid- and collagen-induced aggregation. The CrTXs-induced aggregation in washed platelets was significantly augmented in the presence of Ca2+. The pretreatment with verapamil failed to modify this augmentation of aggregation. The concentration of cytoplasmic-free calcium ([Ca2+]i) of platelets was increased by CrTXs at the same concentrations that produced aggregation. This effect of CrTXs was again little affected by verapamil. CrTXs at the same concentrations as those that produced aggregation and increased [Ca2+]i caused depolarization of platelets, which was unchanged after pretreatment with sodium or potassium transport inhibitors. CrTX-I significantly increased the 22Na flux into platelets and this effect of CrTX-I was unaffected by tetrodotoxin. The CrTX-I-induced aggregation, depolarization, and increase in [Ca2+]i were all significantly attenuated in the low Na+ medium. These results suggest that CrTXs cause a massive depolarization by increasing cation permeability and this generalized depolarization permits an inward movement of Ca2+ down its electrochemical gradient which, in turn, triggers platelet aggregation.

PROTEINS IN NUCLEOCYTOPLASMIC INTERACTIONS

PubMed Central

Goldstein, Lester; Prescott, David M.

1967-01-01

By the transplantation of amino acid-3H-labeled nuclei between cells and the subsequent isolation of nuclei for quantitative assay, we have confirmed that all the nuclear proteins of Amoeba proteus are divisible into two classes that are sharply defined by their physiological behavior. About 40% of the proteins in the nucleus rapidly migrates back and forth between the nucleus and the cytoplasm. These rapidly migrating proteins (RMP) are 25–50 times more concentrated in the nucleus than in the cytoplasm, and migration into the nucleus therefore occurs against a high concentration differential. The remaining 60% of nuclear proteins has been classified as slow turnover proteins (STP) since (as reported in a following paper) virtually all of them ultimately undergo turnover. Turnover in this context means loss of label from the nucleus, by either protein breakdown or protein migration to the cytoplasm. Isolation of nuclei in the detergent Triton X-100 results in a 20% loss of nuclear proteins but conclusions about RMP and STP were not found to be significantly affected by this loss. PMID:6036526

Lentiviral-Mediated Gene Therapy in Fanconi Anemia-A Mice Reveals Long-Term Engraftment and Continuous Turnover of Corrected HSCs.

PubMed

Molina-Estevez, F Javier; Nowrouzi, Ali; Lozano, M Luz; Galy, Anne; Charrier, Sabine; von Kalle, Christof; Guenechea, Guillermo; Bueren, Juan A; Schmidt, Manfred

2015-01-01

Fanconi anemia is a DNA repair-deficiency syndrome mainly characterized by cancer predisposition and bone marrow failure. Trying to restore the hematopoietic function in these patients, lentiviral vector-mediated gene therapy trials have recently been proposed. However, because no insertional oncogenesis studies have been conducted so far in DNA repair-deficiency syndromes such as Fanconi anemia, we have carried out a genome-wide screening of lentiviral insertion sites after the gene correction of Fanca(-/-) hematopoietic stem cells (HSCs), using LAM-PCR and 454-pyrosequencing. Our studies first demonstrated that transduction of Fanca(-/-) HSCs with a lentiviral vector designed for clinical application efficiently corrects the phenotype of Fanconi anemia repopulating cells without any sign of toxicity. The identification of more than 6,500 insertion sites in primary and secondary recipients showed a polyclonal pattern of reconstitution, as well as a continuous turnover of corrected Fanca(-/-) HSC clones, without evidences of selection towards specific common integration sites. Taken together our data show, for the first time in a DNA repair-deficiency syndrome, that lentiviral vector-mediated gene therapy efficiently corrects the phenotype of affected HSCs and promotes a healthy pattern of clonal turnover in vivo. These studies will have a particular impact in the development of new gene therapy trials in patients affected by DNA repair syndromes, particularly in Fanconi anemia.

Are we on the same page? Staff nurse and manager perceptions of work environment, quality of care and anticipated nurse turnover.

PubMed

Gormley, Denise K

2011-01-01

The purpose was to examine differences in perceptions of work environment and quality of care between nurse managers and staff nurses, and the relationship between nurses' perceptions of the work environment and intention to leave. It is important for managers to understand how staff nurses perceive the work environment as these perceptions may affect nurses' intention to leave the organization. Few studies have examined the perceptions of nurses compared with nurse manager/directors regarding the organizational influences on intention to leave. This study was a cross-sectional, non-experimental design. A total of 336 nurses and managers participated from two Midwestern hospitals. Participants completed the Perceived Nurse Work Environment Scale (PNWE), Anticipated Turnover Scale (ATS), and a researcher developed perception of quality scale. Data were analysed for descriptive statistics, Analysis of Variance, and Pearson's correlation. Significant differences were found between nurses and managers on perceptions of work environment. Managers rated work environment higher than staff on all subscales. Work environment was related to anticipated turnover. Managers and staff nurses are 'not on the same page' in perceptions of work environment. Nurse managers need to understand the organizational influences that may affect nurses' intention to leave. Strategies to improve the work environment are necessary to meet the needs of the staff nurse. © 2010 The Author. Journal compilation © 2010 Blackwell Publishing Ltd.

Increasing dietary nitrate has no effect on cancellous bone loss or fecal microbiome in ovariectomized rats.

PubMed

Conley, Melissa N; Roberts, Cooper; Sharpton, Thomas J; Iwaniec, Urszula T; Hord, Norman G

2017-05-01

Studies suggest diets rich in fruit and vegetables reduce bone loss, although the specific compounds responsible are unknown. Substrates for endogenous nitric oxide (NO) production, including organic nitrates and dietary nitrate, may support NO production in age-related conditions, including osteoporosis. We investigated the capability of dietary nitrate to improve NO bioavailability, reduce bone turnover and loss. Six-month-old Sprague Dawley rats [30 ovariectomized (OVX) and 10 sham-operated (sham)] were randomized into three groups: (i) vehicle (water) control, (ii) low-dose nitrate (LDN, 0.1 mmol nitrate/kg bw/day), or (iii) high-dose nitrate (HDN, 1.0 mmol nitrate/kg bw/day) for three weeks. The sham received vehicle. Serum bone turnover markers; bone mass, mineral density, and quality; histomorphometric parameters; and fecal microbiome were examined. Three weeks of LDN or HDN improved NO bioavailability in a dose-dependent manner. OVX resulted in cancellous bone loss, increased bone turnover, and fecal microbiome changes. OVX increased relative abundances of Firmicutes and decreased Bacteroideceae and Alcaligenaceae. Nitrate did not affect the skeleton or fecal microbiome. These data indicate that OVX affects the fecal microbiome and that the gut microbiome is associated with bone mass. Three weeks of nitrate supplementation does not slow bone loss or alter the fecal microbiome in OVX. © 2017 The Authors. Molecular Nutrition & Food Research published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Increasing dietary nitrate has no effect on cancellous bone loss or fecal microbiome in ovariectomized rats

PubMed Central

Conley, Melissa N.; Roberts, Cooper; Sharpton, Thomas J.; Iwaniec, Urszula T.

2017-01-01

Scope Studies suggest diets rich in fruit and vegetables reduce bone loss, although the specific compounds responsible are unknown. Substrates for endogenous nitric oxide (NO) production, including organic nitrates and dietary nitrate, may support NO production in age‐related conditions, including osteoporosis. We investigated the capability of dietary nitrate to improve NO bioavailability, reduce bone turnover and loss. Methods and results Six‐month‐old Sprague Dawley rats [30 ovariectomized (OVX) and 10 sham‐operated (sham)] were randomized into three groups: (i) vehicle (water) control, (ii) low‐dose nitrate (LDN, 0.1 mmol nitrate/kg bw/day), or (iii) high‐dose nitrate (HDN, 1.0 mmol nitrate/kg bw/day) for three weeks. The sham received vehicle. Serum bone turnover markers; bone mass, mineral density, and quality; histomorphometric parameters; and fecal microbiome were examined. Three weeks of LDN or HDN improved NO bioavailability in a dose‐dependent manner. OVX resulted in cancellous bone loss, increased bone turnover, and fecal microbiome changes. OVX increased relative abundances of Firmicutes and decreased Bacteroideceae and Alcaligenaceae. Nitrate did not affect the skeleton or fecal microbiome. Conclusion These data indicate that OVX affects the fecal microbiome and that the gut microbiome is associated with bone mass. Three weeks of nitrate supplementation does not slow bone loss or alter the fecal microbiome in OVX. PMID:28087899

Prenatal Stress Induces Long-Term Effects in Cell Turnover in the Hippocampus-Hypothalamus-Pituitary Axis in Adult Male Rats

PubMed Central

Baquedano, Eva; García-Cáceres, Cristina; Diz-Chaves, Yolanda; Lagunas, Natalia; Calmarza-Font, Isabel; Azcoitia, Iñigo; Garcia-Segura, Luis M.; Argente, Jesús; Chowen, Julie A.; Frago, Laura M.

2011-01-01

Subchronic gestational stress leads to permanent modifications in the hippocampus-hypothalamus-pituitary-adrenal axis of offspring probably due to the increase in circulating glucocorticoids known to affect prenatal programming. The aim of this study was to investigate whether cell turnover is affected in the hippocampus-hypothalamus-pituitary axis by subchronic prenatal stress and the intracellular mechanisms involved. Restraint stress was performed in pregnant rats during the last week of gestation (45 minutes; 3 times/day). Only male offspring were used for this study and were sacrificed at 6 months of age. In prenatally stressed adults a decrease in markers of cell death and proliferation was observed in the hippocampus, hypothalamus and pituitary. This was associated with an increase in insulin-like growth factor-I mRNA levels, phosphorylation of CREB and calpastatin levels and inhibition of calpain -2 and caspase -8 activation. Levels of the anti-apoptotic protein Bcl-2 were increased and levels of the pro-apoptotic factor p53 were reduced. In conclusion, prenatal restraint stress induces a long-term decrease in cell turnover in the hippocampus-hypothalamus-pituitary axis that might be at least partly mediated by an autocrine-paracrine IGF-I effect. These changes could condition the response of this axis to future physiological and pathophysiological situations. PMID:22096592

PIGN prevents protein aggregation in the endoplasmic reticulum independently of its function in the GPI synthesis.

PubMed

Ihara, Shinji; Nakayama, Sohei; Murakami, Yoshiko; Suzuki, Emiko; Asakawa, Masayo; Kinoshita, Taroh; Sawa, Hitoshi

2017-02-01

Quality control of proteins in the endoplasmic reticulum (ER) is essential for ensuring the integrity of secretory proteins before their release into the extracellular space. Secretory proteins that fail to pass quality control form aggregates. Here we show the PIGN-1/PIGN is required for quality control in Caenorhabditis elegans and in mammalian cells. In C. elegans pign-1 mutants, several proteins fail to be secreted and instead form abnormal aggregation. PIGN-knockout HEK293 cells also showed similar protein aggregation. Although PIGN-1/PIGN is responsible for glycosylphosphatidylinositol (GPI)-anchor biosynthesis in the ER, certain mutations in C. elegans pign-1 caused protein aggregation in the ER without affecting GPI-anchor biosynthesis. These results show that PIGN-1/PIGN has a conserved and non-canonical function to prevent deleterious protein aggregation in the ER independently of the GPI-anchor biosynthesis. PIGN is a causative gene for some human diseases including multiple congenital seizure-related syndrome (MCAHS1). Two pign-1 mutations created by CRISPR/Cas9 that correspond to MCAHS1 also cause protein aggregation in the ER, implying that the dysfunction of the PIGN non-canonical function might affect symptoms of MCAHS1 and potentially those of other diseases. © 2017. Published by The Company of Biologists Ltd.

Dabigatran affects thrombin-dependent platelet aggregation after a week-long therapy.

PubMed

Sokol, Juraj; Nehaj, Frantisek; Ivankova, Jela; Mokan, Michal; Mokan, Marian; Stasko, Jan

2018-05-29

Dabigatran is a direct thrombin inhibitor. As the main adverse event is bleeding, it is relevant whether dabigatran has additional effects on platelet function. If so, it could affect the bleeding risk. We aimed to assess in vitro aggregation in patients with atrial fibrillation (AF) receiving dabigatran. We evaluated 32 AF patients treated with dabigatran (study group) and 18 non-anticoagulated non-AF blood donors (control group). We assessed light transmittance platelet aggregation (LTA) with 100 nmol/L γ-thrombin in both groups. The LTA was performed at two time-points in our dabigatran group of patients. The thrombin-induced platelet aggregation was significantly lower two hours after dabigatran was taken compared to baseline measurement (9% ± 6% vs. 29% ± 21%) in our study group. Moreover, we observed that the baseline value of platelet aggregation in patients on dabigatran treatment was significantly lower compared to healthy volunteers (29% ± 21% vs. 89 ± 8). However, one subanalysis showed that this significant reduction in platelet aggregation at baseline was only observed in patients who received dabigatran for over a week. The thrombin-induced platelet aggregation is reduced in non-valvular AF patients receiving dabigatran after a week-long therapy.

The Effects of Different Fine Recycled Concrete Aggregates on the Properties of Mortar

PubMed Central

Fan, Cheng-Chih; Huang, Ran; Hwang, Howard; Chao, Sao-Jeng

2015-01-01

The practical use of recycled concrete aggregate produced by crushing concrete waste reduces the consumption of natural aggregate and the amount of concrete waste that ends up in landfills. This study investigated two methods used in the production of fine recycled concrete aggregate: (1) a method that produces fine as well as coarse aggregate, and (2) a method that produces only fine aggregate. Mortar specimens were tested using a variety of mix proportions to determine how the characteristics of fine recycled concrete aggregate affect the physical and mechanical properties of the resulting mortars. Our results demonstrate the superiority of mortar produced using aggregate produced using the second of the two methods. Nonetheless, far more energy is required to render concrete into fine aggregate than is required to produce coarse as well as fine aggregate simultaneously. Thus, the performance benefits of using only fine recycled concrete aggregate must be balanced against the increased impact on the environment.

Piribedil affects dopamine turnover in cochleas stimulated by white noise.

PubMed

Gil-Loyzaga, P; Vicente-Torres, M A; Fernández-Mateos, P; Arce, A; Esquifino, A

1994-09-01

The presence of dopamine (DA) within the cochlea has been previously reported, indicating that its turnover increases under noise stimulation. In the present report, piribedil, a dopaminergic D2 agonist, was used in order to provide evidence of the activity of D2 receptors in the turnover of DA under noise stimulation. Long-Evans rats were intraperitoneally injected with distilled water or with a solution of piribedil one hour previously to either noise or silence exposure. Noise stimulation was performed in an anechoic chamber at 70, 90 or 110 dB SPL for one hour. The animals were then sacrificed and the cochlear contents of DA and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were quantified by HPLC with electrochemical detection. The administration of piribedil to animals kept in silence did not modify the cochlear DA, DOPAC and HVA content. Noise stimulation resulted in a decrease of the cochlear DA content and an increase of the cochlear DOPAC and HVA contents in vehicle treated animals. The administration of piribedil resulted in a blockade of this noise induced cochlear DA turnover. These results suggest that piribedil stimulates cochlear D2 receptors controlling the cochlear DA release. Piribedil action on D2 receptors could explain the improvement observed in some cochleo-vestibular diseases signs after piribedil treatment.

Enhancing Cardiac Triacylglycerol Metabolism Improves Recovery From Ischemic Stress

PubMed Central

Liu, Li; Goldberg, Ira J.

2015-01-01

Elevated cardiac triacylglycerol (TAG) content is traditionally equated with cardiolipotoxicity and suggested to be a culprit in cardiac dysfunction. However, previous work demonstrated that myosin heavy-chain–mediated cardiac-specific overexpression of diacylglycerol transferase 1 (MHC-DGAT1), the primary enzyme for TAG synthesis, preserved cardiac function in two lipotoxic mouse models despite maintaining high TAG content. Therefore, we examined whether increased cardiomyocyte TAG levels due to DGAT1 overexpression led to changes in cardiac TAG turnover rates under normoxia and ischemia-reperfusion conditions. MHC-DGAT1 mice had elevated TAG content and synthesis rates, which did not alter cardiac function, substrate oxidation, or myocardial energetics. MHC-DGAT1 hearts had ischemia-induced lipolysis; however, when a physiologic mixture of long-chain fatty acids was provided, enhanced TAG turnover rates were associated with improved functional recovery from low-flow ischemia. Conversely, exogenous supply of palmitate during reperfusion suppressed elevated TAG turnover rates and impaired recovery from ischemia in MHC-DGAT1 hearts. Collectively, this study shows that elevated TAG content, accompanied by enhanced turnover, does not adversely affect cardiac function and, in fact, provides cardioprotection from ischemic stress. In addition, the results highlight the importance of exogenous supply of fatty acids when assessing cardiac lipid metabolism and its relationship with cardiac function. PMID:25858561

Treatment with Trehalose Prevents Behavioral and Neurochemical Deficits Produced in an AAV α-Synuclein Rat Model of Parkinson's Disease.

PubMed

He, Qing; Koprich, James B; Wang, Ying; Yu, Wen-bo; Xiao, Bao-guo; Brotchie, Jonathan M; Wang, Jian

2016-05-01

The accumulation of misfolded α-synuclein in dopamine (DA) neurons is believed to be of major importance in the pathogenesis of Parkinson's disease (PD). Animal models of PD, based on viral-vector-mediated over-expression of α-synuclein, have been developed and show evidence of dopaminergic toxicity, providing us a good tool to investigate potential therapies to interfere with α-synuclein-mediated pathology. An efficient disease-modifying therapeutic molecule should be able to interfere with the neurotoxicity of α-synuclein aggregation. Our study highlighted the ability of an autophagy enhancer, trehalose (at concentrations of 5 and 2% in drinking water), to protect against A53T α-synuclein-mediated DA degeneration in an adeno-associated virus serotype 1/2 (AAV1/2)-based rat model of PD. Behavioral tests and neurochemical analysis demonstrated a significant attenuation in α-synuclein-mediated deficits in motor asymmetry and DA neurodegeneration including impaired DA neuronal survival and DA turnover, as well as α-synuclein accumulation and aggregation in the nigrostriatal system by commencing 5 and 2% trehalose at the same time as delivery of AAV. Trehalose (0.5%) was ineffective on the above behavioral and neurochemical deficits. Further investigation showed that trehalose enhanced autophagy in the striatum by increasing formation of LC3-II. This study supports the concept of using trehalose as a novel therapeutic strategy that might prevent/reverse α-synuclein aggregation for the treatment of PD.

Monitoring protein turnover during phosphate starvation-dependent autophagic degradation using a photoconvertible fluorescent protein aggregate in tobacco BY-2 cells

PubMed Central

Tasaki, Maiko; Asatsuma, Satoru; Matsuoka, Ken

2014-01-01

We have developed a system for quantitative monitoring of autophagic degradation in transformed tobacco BY-2 cells using an aggregate-prone protein comprised of cytochrome b5 (Cyt b5) and a tetrameric red fluorescent protein (RFP). Unfortunately, this system is of limited use for monitoring the kinetics of autophagic degradation because the proteins synthesized before and after induction of autophagy cannot be distinguished. To overcome this problem, we developed a system using kikume green-red (KikGR), a photoconvertible and tetrameric fluorescent protein that changes its fluorescence from green to red upon irradiation with purple light. Using the fusion protein of Cyt b5 and KikGR together with a method for the bulk conversion of KikGR, which we had previously used to convert the Golgi-localized monomeric KikGR fusion protein, we were able to monitor both the growth and de novo formation of aggregates. Using this system, we found that tobacco cells do not cease protein synthesis under conditions of phosphate (Pi)-starvation. Induction of autophagy under Pi-starvation, but not under sugar- or nitrogen-starvation, was specifically inhibited by phosphite, which is an analog of Pi with a different oxidation number. Therefore, the mechanism by which BY-2 cells can sense Pi-starvation and induce autophagy does not involve sensing a general decrease in energy supply and a specific Pi sensor might be involved in the induction of autophagy under Pi-starvation. PMID:24817874

Monitoring protein turnover during phosphate starvation-dependent autophagic degradation using a photoconvertible fluorescent protein aggregate in tobacco BY-2 cells.

PubMed

Tasaki, Maiko; Asatsuma, Satoru; Matsuoka, Ken

2014-01-01

We have developed a system for quantitative monitoring of autophagic degradation in transformed tobacco BY-2 cells using an aggregate-prone protein comprised of cytochrome b5 (Cyt b5) and a tetrameric red fluorescent protein (RFP). Unfortunately, this system is of limited use for monitoring the kinetics of autophagic degradation because the proteins synthesized before and after induction of autophagy cannot be distinguished. To overcome this problem, we developed a system using kikume green-red (KikGR), a photoconvertible and tetrameric fluorescent protein that changes its fluorescence from green to red upon irradiation with purple light. Using the fusion protein of Cyt b5 and KikGR together with a method for the bulk conversion of KikGR, which we had previously used to convert the Golgi-localized monomeric KikGR fusion protein, we were able to monitor both the growth and de novo formation of aggregates. Using this system, we found that tobacco cells do not cease protein synthesis under conditions of phosphate (Pi)-starvation. Induction of autophagy under Pi-starvation, but not under sugar- or nitrogen-starvation, was specifically inhibited by phosphite, which is an analog of Pi with a different oxidation number. Therefore, the mechanism by which BY-2 cells can sense Pi-starvation and induce autophagy does not involve sensing a general decrease in energy supply and a specific Pi sensor might be involved in the induction of autophagy under Pi-starvation.

Temperature & wood source control PyOM turnover in a Northern American forest

NASA Astrophysics Data System (ADS)

Hatton, Pierre-Joseph; Le Moine, James; Auclerc, Apolline; Gormley, Mark; Filley, Tim R.; Nadelhoffer, Knute J.; Bird, Jeff. A.

2016-04-01

Surprisingly little is known about how pyrolysis temperature and wood source affect the stability of forest-fire derived pyrogenic organic matter (PyOM). Here, we show that wood source and temperature affect in situ mineralization rates of PyOM in soils for two co-occurring gymnosperm (jack pine; JP [Pinus banksiana]) and angiosperm (red maple; RM [Acer rubrum])¬ species from North American boreal-temperate ecotones. We assess the effect of pyrolysis temperature on PyOM fates by following the decay of 13C/15N-enriched JP wood (JPwood) and PyOM produced at 300 °C (JP300) and 450 °C (JP450); and assess the effect of PyOM wood source by comparing fates of JP450 and RM450. JPwood mineralized 18× faster than JP300 and 44× faster than JP450 after 2.8y. RM450 mineralized initially faster than JP450 during the first ~2y, but became equivalent afterwards (1.1±0.2% of CO¬2 losses after 2.8y). Modeled turnover times suggest that this can be attributed to ~1% of fast-cycling PyOM (<3y). Slower-cycling pools are 12× faster for JPwood (13±5y) than for JP300 (157±28y) and 55× faster than for JP450 (700±229y). Modeled turnover times of the slow-cycling pools were equivalent for JP450 and RM450. The priming effect was positive for JPwood (0.10±0.05), neutral for JP300 (-0.02±0.04), and negative for JP450 (-0.15±0.03) and RM50 (-0.59±0.03). DOC losses were minimal compared with CO2 losses (DOC:CO2 ratio ≤0.005), but followed the same patterns: JPwood 6× greater than that of JP300 and 39× greater compared with JP450. After 1y, C recoveries were lower for JPwood than for PyOM, with no influence of pyrolysis temperature or wood source (yet); N recoveries did not differ. PLFA-(13)C data reveal that (i) treatments have similar microbial communities after 1y, (ii) JPwood is preferentially utilized by fungi, and (iii) bacteria increasingly utilize PyOM as pyrolysis temperature increases. Estimated carbon use efficiency decreased with increasing pyrolysis temperature (JPwood~JP300>JP450~RM450). Although insignificant, potential phenol oxidase and peroxidase activities decrease with increasing pyrolysis temperature. Neither PyOM nor wood additions (~11% of soil C stock 0-20 cm depth) affected pH or Ec after 1y. We provide the first, field experimental evidence that pyrolysis temperature and wood source affect the turnover of PyOM in soil. We show faster, initial decay for PyOM produced at lesser temperature and RM (angiosperm) compared with JP (gymnosperm). This study offers realistic insights on (i) the controls underlying in situ PyOM turnover, and on (ii) how ongoing/projected changes in tree species composition and fire frequency/intensity/distribution may affect PyOM in soil of North America temperate-boreal ecotones.

Performance Testing of Hot-Mix Asphalt Aggregates

DOT National Transportation Integrated Search

1999-12-01

Hot mix asphalt (HMA) pavements are subject to thermal cracking, fatigue cracking, rutting, stripping, raveling, and freeze-thaw damage. Some of these distresses are directly affected by the choice of aggregates. Particle shape, surface texture, part...

Alternative powertrain strategies and fleet turnover in the 21st century.

DOT National Transportation Integrated Search

2010-08-01

The changes taking place in the global automotive industry related to alternative : powertrains and fuels are affecting each country or region differently. Each country or : region has its own policies in place to monitor and manage vehicle fuel cons...

Soil aggregate stratification of nematodes and ammonia oxidizers affects nitrification in an acid soil.

PubMed

Jiang, Yuji; Jin, Chen; Sun, Bo

2014-10-01

Nitrification plays a central role in global nitrogen cycle, which is affected by interaction between soil microfauna and microorganisms. The impact of synchronized changes in nematodes and ammonia oxidizers within aggregate fractions on nitrification was investigated in an acid soil under 10-year manure application. Nematodes, ammonia oxidizers and potential nitrification activity (PNA) were examined in three soil aggregate fractions under four fertilization regimes. Pyrosequencing data revealed that the dominant bacterial amoA operational taxonomic units (OTUs) were related to Nitrosospira species, while archaeal OTUs were affiliated with Nitrososphaera and Nitrosotalea species. PNA was more strongly correlated with ammonia-oxidizing bacteria (AOB) abundance than ammonia-oxidizing archaea (AOA) abundance, although AOA were dominant in the acid soil. Plant parasites had a negative effect on AOB abundance; however, bacterivores stimulated AOB abundance and contributed more to PNA than plant parasites. Aggregate fractions exerted significant impacts on AOA abundance and AOB community composition. Total carbon content strongly affected the abundance and composition of AOA community, while soil pH primarily affected that of AOB community. Soil variables explained 62.7% and 58.1% variations, and nematode variables explained 11.7% and 19.5% variations in the AOA and AOB community composition respectively. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

PM10 emissions from aggregate fractions of an Entic Haplustoll under two contrasting tillage systems

NASA Astrophysics Data System (ADS)

Mendez, Mariano J.; Aimar, Silvia B.; Buschiazzo, Daniel E.

2015-12-01

Tillage systems affect physical and chemical properties of soils modifying its aggregation. How changes of the aggregate size distribution affect the capacity of the soil to emit fine particulate matter (PM10) to the atmosphere during wind erosion processes, is a less investigated issue. In order to answer this question, PM10 emissions from an Entic Haplustoll submitted to 25 years of continuous conventional tillage (LC) and no-till (NT) were analyzed. Soil samples were sieved with a rotary sieve in order to determine the aggregate size distribution (fractions : <0.42 mm, 0.42-0.84 mm, 0.84-2 mm, 2-6.4 mm, 6.4-19.2 mm, and >19.2 mm), the dry aggregate stability (DAS) and the erodible fraction (EF). The organic matter contents (OM), the particle size composition and the PM10 emission of each aggregate fraction were also measured. Results showed that NT promoted OM accumulations in all aggregate fractions which favored DAS and soil aggregation. The <0.42 mm sized aggregates (27%) predominated in CT and the >19.2 mm (41.7%) in NT, while the proportion of the other aggregate fractions was similar in both tillage systems. As a consequence of the smaller proportion of the <0.42 mm aggregates, the erodible fraction was lower in NT (EF: 17.3%) than in CT (30.8%). PM10 emissions of each aggregate fraction (AE) decreased exponentially with increasing size of the fractions in both tillage systems, mainly as a consequence of the smaller size and higher specific surface. AE was higher in CT than in NT for all aggregate fractions, but the higher differences were found in the <0.42 mm aggregates (18 μg g-1 in CT vs 8 μg g-1 in NT). The PM10 emission of the whole soil was three times higher in CT than in NT, while the emission of the erodible fraction (EFE) was in CT four times higher than in NT. PM10 emissions of the <0.42 mm aggregates represented over 50% of SE and 90% of EFE. We concluded that NT reduced the capacity of soils of the semiarid Pampas to emit PM10 because it produced a better aggregation that reduced the proportion and emission of the <0.42 mm aggregates. These aggregates had, by far, the highest emission potential.

The role of high-involvement work practices and professional self-image in nursing recruits' turnover: A three-year prospective study.

PubMed

Chênevert, Denis; Jourdain, Geneviève; Vandenberghe, Christian

2016-01-01

The retention of young graduate nurses has become a major management challenge among hospitals in Western countries, which is amplified in a context of aging of populations and an increasing demand for services from patients. Moreover, as it has been reported that 50% of experienced nurses do not recommend a career in nursing, it is likely that retention problems occur not only at the level of the organization, but also at the level of the nursing profession. Although research has identified some predictors of nurse turnover, it is unclear which factors influence nurses' turnover from the organization and from the profession and how these factors interrelate with one another over time. The present study extends previous research on nurse turnover by looking at the combined effects of nurses' pre-entry expectations, perceived high-involvement work practices, and professional self-image, on intended and actual turnover from the organization and the profession. A prospective, longitudinal study of a sample of 160 graduated nurses affiliated with the Quebec Nurses' Association, Canada, was conducted. Participants were surveyed at three points in time, spread over a 3-year period. Graduated nurses' pre-entry expectations and professional self-image were surveyed at graduation (Time 1), while perceived high-involvement work practices, professional self-image, and intention to leave the organization and the profession were captured six months following nurses' entry into the labor market (Time 2). Finally, participants were surveyed with respect to organizational and professional turnover three years after the Time 2 survey (Time 3). Structural equations modeling was used to examine the structure of the measures and the relationships among the constructs. Although pre-entry expectations had no effect, perceived high-involvement work practices were positively related to Time 2, professional self-image (controlling for pre-entry professional self-image). Moreover, high-involvement work practices exerted an indirect, negative effect on organizational and professional turnover through intention to leave the organization, and an indirect negative effect on intention to leave the profession through professional self-image. Nonetheless, professional self-image did not affect turnover. The current study indicates that hospitals and nurse directors can take advantage of developing high-involvement work practices as these practices foster a stronger professional self-image among nurses, thereby contributing to their sense of value as care providers, and indirectly reduce intended and actual turnover from the organization and the profession. Copyright © 2015 Elsevier Ltd. All rights reserved.

Newly graduated nurses' occupational commitment and its associations with professional competence and work-related factors.

PubMed

Numminen, Olivia; Leino-Kilpi, Helena; Isoaho, Hannu; Meretoja, Riitta

2016-01-01

To explore newly graduated nurses' occupational commitment and its associations with their self-assessed professional competence and other work-related factors. As a factor affecting nurse turnover, newly graduated nurses' occupational commitment and its associations with work-related factors needs exploring to retain adequate workforce. Nurses' commitment has mainly been studied as organisational commitment, but newly graduated nurses' occupational commitment and its association with work-related factors needs further studying. This study used descriptive, cross-sectional, correlation design. A convenience sample of 318 newly graduated nurses in Finland participated responding to an electronic questionnaire. Statistical software, NCSS version 9, was used in data analysis. Frequencies, percentages, ranges, means and standard deviations summarised the data. Multivariate Analyses of Variance estimated associations between occupational commitment and work-related variables. IBM SPSS Amos version 22 estimated the model fit of Occupational Commitment Scale and Nurse Competence Scale. Newly graduated nurses' occupational commitment was good, affective commitment reaching the highest mean score. There was a significant difference between the nurse groups in favour of nurses at higher competence levels in all subscales except in limited alternatives occupational commitment. Multivariate analyses revealed significant associations between subscales of commitment and competence, turnover intentions, job satisfaction, earlier professional education and work sector, competence counting only through affective dimension. The association between occupational commitment and low turnover intentions and satisfaction with nursing occupation was strong. Higher general competence indicated higher overall occupational commitment. Managers' recognition of the influence of all dimensions of occupational commitment in newly graduated nurses' professional development is important. Follow-up studies of newly graduated nurses' commitment, its relationship with quality care, managers' role in enhancing commitment and evaluation of the impact of interventions on improving commitment need further studying. © 2015 John Wiley & Sons Ltd.

Spatial pattern affects diversity-productivity relationships in experimental meadow communities

NASA Astrophysics Data System (ADS)

Lamošová, Tereza; Doležal, Jiří; Lanta, Vojtěch; Lepš, Jan

2010-05-01

Plant species create aggregations of conspecifics as a consequence of limited seed dispersal, clonal growth and heterogeneous environment. Such intraspecific aggregation increases the importance of intraspecific competition relative to interspecific competition which may slow down competitive exclusion and promote species coexistence. To examine how spatial aggregation impacts the functioning of experimental assemblages of varying species richness, eight perennial grassland species of different growth form were grown in random and aggregated patterns in monocultures, two-, four-, and eight-species mixtures. In mixtures with an aggregated pattern, monospecific clumps were interspecifically segregated. Mixed model ANOVA was used to test (i) how the total productivity and productivity of individual species is affected by the number of species in a mixture, and (ii) how these relationships are affected by spatial pattern of sown plants. The main patterns of productivity response to species richness conform to other studies: non-transgressive overyielding is omnipresent (the productivity of mixtures is higher than the average of its constituent species so that the net diversity, selection and complementarity effects are positive), whereas transgressive overyielding is found only in a minority of cases (average of log(overyielding) being close to zero or negative). The theoretical prediction that plants in a random pattern should produce more than in an aggregated pattern (the distances to neighbours are smaller and consequently the competition among neighbours stronger) was confirmed in monocultures of all the eight species. The situation is more complicated in mixtures, probably as a consequence of complicated interplay between interspecific and intraspecific competition. The most productive species ( Achillea, Holcus, Plantago) were competitively superior and increased their relative productivity with mixture richness. The intraspecific competition of these species is stronger than that of most other species. The aggregated pattern in the full mixture increased the survival of subordinate species, and consequently, we conclude that an aggregated pattern can promote species coexistence (or at least postpone competitive exclusion), particularly in comparison with homogeneously sown mixtures.

Short-term turnover of soil organic matter after tillage proven by Pyrolysis-field ionization MS

NASA Astrophysics Data System (ADS)

Fiedler, Sebastian; Jurasinski, Gerald; Leinweber, Peter; Glatzel, Stephan

2015-04-01

Knowledge about the composition and the turnover dynamics of soil organic matter (SOM) is crucial to the fertility of agricultural soils. Even short-term changes of SOM are of fundamental importance. Tillage changes the decomposition and the mineralisation of SOM. By disrupting macroaggregates, tillage induces an increased turnover and hampers the aggregation of SOM. As a consequence, mineralisation of SOM is stimulated which may imply an additional efflux of CO2 and N2O from soil. Pyrolysis-field ionization mass spectrometry (Py-FIMS) has been developed as a key method for SOM research. This powerful analytical tool allows a rapid, global and objective determination of the majority of chemical compound classes and is an appropriate method for the analysis of even small differences of biogeochemical matters. Hence, Py-FIMS may allow for a precise detection of the turnover of SOM and the involved compounds that are affected by tillage in the short-term. Py-FIMS measurements along with the determination of the CO2 and N2O effluxes from soil after tillage at the same site may give new insights into the compounds of SOM which are mineralised and consequently contribute to fundamental processes such as respiration, nitrification and denitrification. We applied Py-FIMS to soil samples from a stagnic Luvisol taken before and after tillage from a harvested maize field in Northern Germany. The samples were taken from two treatments amended with mineral fertiliser (MF) and biogas residues (BR), respectively, and also from an unfertilised control (UC). Tillage was conducted by disc harrowing, followed by mouldboard ploughing up to 30 cm. Simultaneously the soil efflux of CO2 and N2O was measured with a dynamic chamber technique. Before tillage, the mass spectra showed distinct differences in the relative ion intensities: the BR treatment showed much more volatilised matter during pyrolysis indicating an increased amount of SOM. Furthermore, in this treatment, the proportions of carbohydrates, peptides and N-heterocycles were smaller and those of lipids and sterols had larger values than in the other treatments, most likely attributable to the cattle manure used for the biogas feedstock and to relative enrichments during anaerobic fermentation. Only a few days after tillage significant changes in SOM composition were observed, especially in the BR treatment: the proportions of volatilised matter and the relative signal intensities of carbohydrates, phenols + lignin monomers, N-heterocycles and peptides increased, whereas those of lignin dimers, lipids and sterols decreased. In the MF treatment only an increase of lipid proportions at the expense of carbohydrates was observed. The decrease and the increase of carbohydrates in MF and BR, respectively, were reciprocally correlated with the cumulated CO2 efflux. The N2O efflux increased in MF and BR after tillage, but not in UC. Thus, we were able to show significant changes in the quality of SOM due to tillage confirming the sensitivity of Py-FIMS to detected even short-term changes in SOM composition that could be related to the release of gases from soil.

The Effects of the Second Victim Phenomenon on Work-Related Outcomes: Connecting Self-Reported Caregiver Distress to Turnover Intentions and Absenteeism.

PubMed

Burlison, Jonathan D; Quillivan, Rebecca R; Scott, Susan D; Johnson, Sherry; Hoffman, James M

2016-11-02

Second victim experiences can affect the well-being of healthcare providers and compromise patient safety. The purpose of this study was to assess the relationships between self-reported second victim-related distress to turnover intention and absenteeism. Organizational support was examined concurrently because it was hypothesized to explain the potential relationships between distress and work-related outcomes. A cross-sectional, self-report survey (the Second Victim Experience and Support Tool) of nurses directly involved in patient care (N = 155) was analyzed by using hierarchical linear regression. The tool assesses organizational support, distress due to patient safety event involvement, and work-related outcomes. Second victim distress was significantly associated with turnover intentions (P < 0.001) and absenteeism (P < 0.001), while controlling for the effects of demographic variables. Organizational support fully mediated the distress-turnover intentions (P < 0.05) and distress-absenteeism (P < 0.05) relationships, which indicates that perceptions of organizational support may explain turnover intentions and absenteeism related to the second victim experience. Involvement in patient safety events and the important role of organizational support in limiting caregiver event-related trauma have been acknowledged. This study is one of the first to connect second victim distress to work-related outcomes. This study reinforces the efforts health care organizations are making to develop resources to support their staff after patient safety events occur. This study broadens the understanding of the negative effects of a second victim experience and the need to support caregivers as they recover from adverse event involvement.

7 CFR 51.2933 - Serious damage.

Code of Federal Regulations, 2010 CFR

2010-01-01

... seriously affects the appearance. (e) Scab spots when cracked or when well healed and aggregating more than... aggregating more than one-half inch (12.7 mm) in diameter. (g) Hail when the skin has been broken or when more...

7 CFR 51.2933 - Serious damage.

Code of Federal Regulations, 2012 CFR

2012-01-01

... seriously affects the appearance. (e) Scab spots when cracked or when well healed and aggregating more than... aggregating more than one-half inch (12.7 mm) in diameter. (g) Hail when the skin has been broken or when more...

7 CFR 51.2933 - Serious damage.

Code of Federal Regulations, 2011 CFR

2011-01-01

... seriously affects the appearance. (e) Scab spots when cracked or when well healed and aggregating more than... aggregating more than one-half inch (12.7 mm) in diameter. (g) Hail when the skin has been broken or when more...

The factorial structure of job-related affective well-being: Polish adaptation of the Warr's measure.

PubMed

Mielniczuk, Emilia; Łaguna, Mariola

2018-02-16

The first aim of the study reported in this article was to test the factorial structure of job-related affect in a Polish sample. The second aim was to develop the Polish adaptation of the Warr's job-related affective well-being measure published in 1990, which is designed to assess 4 types of affect at work: anxiety, comfort, depression, enthusiasm. A longitudinal study design with 2 measurement times was used for verifying the psychometric properties of the Polish version of the measure. The final sample consisted of 254 Polish employees from different professions. Participants were asked to fill in a set of questionnaires consisting of measures capturing job-related affective well-being, mood, and turnover intention. The first step of analysis was to test the theoretically-based structure of the job-related affective well-being measure in a Polish sample. The confirmatory factor analysis revealed that a 4-factor model best describes the structure of the measure in comparison to 5 alternative models. Next, reliability of this measure was assessed. All scales achieved good internal consistency and acceptable test-retest reliability after 2 weeks. Finally, the convergent and discriminant validity as well as the criterion and predictive validity of all job-related affective well-being scales was confirmed, based on correlations between job-related affect and mood as well as turnover intention. The results suggest that the Polish adaptation of Warr's job-related affective well-being measure can be used by scientists as well as by practitioners who aim at assessing 4 types of affective well-being at a work context. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Computational design and biophysical characterization of aggregation-resistant point mutations for γD crystallin illustrate a balance of conformational stability and intrinsic aggregation propensity.

PubMed

Sahin, Erinc; Jordan, Jacob L; Spatara, Michelle L; Naranjo, Andrea; Costanzo, Joseph A; Weiss, William F; Robinson, Anne Skaja; Fernandez, Erik J; Roberts, Christopher J

2011-02-08

γD crystallin is a natively monomeric eye-lens protein that is associated with hereditary juvenile cataract formation. It is an attractive model system as a multidomain Greek-key protein that aggregates through partially folded intermediates. Point mutations M69Q and S130P were used to test (1) whether the protein-design algorithm RosettaDesign would successfully predict mutants that are resistant to aggregation when combined with informatic sequence-based predictors of peptide aggregation propensity and (2) how the mutations affected relative unfolding free energies (ΔΔG(un)) and intrinsic aggregation propensity (IAP). M69Q was predicted to have ΔΔG(un) ≫ 0, without significantly affecting IAP. S130P was predicted to have ΔΔG(un) ∼ 0 but with reduced IAP. The stability, conformation, and aggregation kinetics in acidic solution were experimentally characterized and compared for the variants and wild-type (WT) protein using circular dichroism and intrinsic fluorescence spectroscopy, calorimetric and chemical unfolding, thioflavin-T binding, chromatography, static laser light scattering, and kinetic modeling. Monomer secondary and tertiary structures of both variants were indistinguishable from WT, while ΔΔG(un) > 0 for M69Q and ΔΔG(un) < 0 for S130P. Surprisingly, despite being the least conformationally stable, S130P was the most resistant to aggregation, indicating a significant decrease of its IAP compared to WT and M69Q.

Optimization and influence of parameter affecting the compressive strength of geopolymer concrete containing recycled concrete aggregate: using full factorial design approach

NASA Astrophysics Data System (ADS)

Krishnan, Thulasirajan; Purushothaman, Revathi

2017-07-01

There are several parameters that influence the properties of geopolymer concrete, which contains recycled concrete aggregate as the coarse aggregate. In the present study, the vital parameters affecting the compressive strength of geopolymer concrete containing recycled concrete aggregate are analyzedby varying four parameters with two levels using full factorial design in statistical software Minitab® 17. The objective of the present work is to gain an idea on the optimization, main parameter effects, their interactions and the predicted response of the model generated using factorial design. The parameters such as molarity of sodium hydroxide (8M and 12M), curing time (6hrs and 24 hrs), curing temperature (60°C and 90°C) and percentage of recycled concrete aggregate (0% and 100%) are considered. The results show that the curing time, molarity of sodium hydroxide and curing temperature were the orderly significant parameters and the percentage of Recycled concrete aggregate (RCA) was statistically insignificant in the production of geopolymer concrete. Thus, it may be noticeable that the RCA content had negligible effect on the compressive strength of geopolymer concrete. The expected responses from the generated model showed a satisfactory and rational agreement to the experimental data with the R2 value of 97.70%. Thus, geopolymer concrete comprising recycled concrete aggregate can solve the major social and environmental concerns such as the depletion of the naturally available aggregate sources and disposal of construction and demolition waste into the landfill.

Teachers' Views on Causes Leading to Their Burnout

ERIC Educational Resources Information Center

El Helou, Maya; Nabhani, Mona; Bahous, Rima

2016-01-01

Teaching is a challenging profession sometimes leading to teachers' burnout: a syndrome of emotional exhaustion, depersonalisation, and reduced personal accomplishment. Burnout effects range from psychological, physical, and behavioural symptoms to increased turnover, which affects students and schools. This study identifies levels of and factors…

Pig slurry acidification and separation techniques affect soil N and C turnover and N2O emissions from solid, liquid and biochar fractions.

PubMed

Gómez-Muñoz, B; Case, S D C; Jensen, L S

2016-03-01

The combined effects of pig slurry acidification, subsequent separation techniques and biochar production from the solid fraction on N mineralisation and N2O and CO2 emissions in soil were investigated in an incubation experiment. Acidification of pig slurry increased N availability from the separated solid fractions in soil, but did not affect N2O and CO2 emissions. However acidification reduced soil N and C turnover from the liquid fraction. The use of more advanced separation techniques (flocculation and drainage > decanting centrifuge > screw press) increased N mineralisation from acidified solid fractions, but also increased N2O and CO2 emissions in soil amended with the liquid fraction. Finally, the biochar production from the solid fraction of pig slurry resulted in a very recalcitrant material, which reduced N and C mineralisation in soil compared to the raw solid fractions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Factors Associated With Care Workers' Intention to Leave Employment in Nursing Homes: A Secondary Data Analysis of the Swiss Nursing Homes Human Resources Project.

PubMed

Gaudenz, Clergia; De Geest, Sabina; Schwendimann, René; Zúñiga, Franziska

2017-07-01

The emerging care personnel shortage in Swiss nursing homes is aggravated by high turnover rates. As intention to leave is a predictor of turnover, awareness of its associated factors is essential. This study applied a secondary data analysis to evaluate the prevalence and variability of 3,984 nursing home care workers' intention to leave. Work environment factors and care worker outcomes were tested via multiple regression analysis. Although 56% of care workers reported intention to leave, prevalences varied widely between facilities. Overall, intention to leave showed strong inverse relationships with supportive leadership and affective organizational commitment and weaker positive relationships with stress due to workload, emotional exhaustion, and care worker health problems. The strong direct relationship of nursing home care workers' intention to leave with affective organizational commitment and perceptions of leadership quality suggest that multilevel interventions to improve these factors might reduce intention to leave.

Non-Arrhenius protein aggregation.

PubMed

Wang, Wei; Roberts, Christopher J

2013-07-01

Protein aggregation presents one of the key challenges in the development of protein biotherapeutics. It affects not only product quality but also potentially impacts safety, as protein aggregates have been shown to be linked with cytotoxicity and patient immunogenicity. Therefore, investigations of protein aggregation remain a major focus in pharmaceutical companies and academic institutions. Due to the complexity of the aggregation process and temperature-dependent conformational stability, temperature-induced protein aggregation is often non-Arrhenius over even relatively small temperature windows relevant for product development, and this makes low-temperature extrapolation difficult based simply on accelerated stability studies at high temperatures. This review discusses the non-Arrhenius nature of the temperature dependence of protein aggregation, explores possible causes, and considers inherent hurdles for accurately extrapolating aggregation rates from conventional industrial approaches for selecting accelerated conditions and from conventional or more advanced methods of analyzing the resulting rate data.

Fate of lignin, cutin and suberin in soil organic matter fractions - an incubation experiment

NASA Astrophysics Data System (ADS)

Mueller, Carsten W.; Mueller, Kevin E.; Freeman, Katherine H.; Ingrid, Kögel-Knabner

2010-05-01

The turnover of soil organic matter (SOM) is controlled by its chemical composition, its spatial accessibility and the association with the mineral phase. Separation of bulk soils by physical fractionation and subsequent chemical analysis of these fractions should give insights to how compositional differences in SOM drive turnover rates of different size-defined carbon pools. The main objective of this study was to elucidate the relative abundance and recalcitrance of lignin, cutin and suberin in aggregated bulk soils and SOM fractions in the course of SOM decomposition. Bulk soils and physically-separated size fractions (sand, silt and clay) of the Ah horizon of a forest soil (under Picea abies L.Karst) were parallel incubated over a period of one year. In order to differentiate between particulate OM (POM) and mineral-associated SOM the particle size fractions were additionally separated by density after the incubation experiment. We used solid-state 13C-CPMAS NMR spectroscopy and GC-MS (after copper oxide oxidation and solvent extraction) to analyze the composition of the incubated samples. The abundance and isotopic composition (including 13C and 14C) of the respired CO2 further enabled us to monitor the dynamics of SOM mineralization. This approach allowed for differentiating between C stabilization of soil fractions due to accessibility/aggregation and to biochemical recalcitrance at different scales of resolution (GC-MS, NMR). We found a relative enrichment of alkyl C and decreasing lignin contents in the order of sand < silt < clay by 13C-NMR spectroscopy and GC-MS within soils and fractions before the incubation, resulting in increased lipid to lignin ratios with decreasing particle size. An accumulation of aliphatic C compounds was especially found for the small silt and clay sized particulate OM (POM). For the fresh particulate OM (POM) of the sand fraction a clear decay of lignin was observed in the course of the incubation experiment, indicated by decreasing C/V and increasing ac/alV ratios. A relative decrease of aliphatic C in the incubated fractions compared to the incubated bulk soils showed the preferential mineralization of less recalcitrant C compounds that were spatially inaccessible in aggregates of the bulk soil. Differences in the abundance of lignin monomers, hydroxyl acids, n-alkanols and n-fatty acid methyl esters measured by GC MS before and after the incubation indicated selective degradation and preservation patterns at the molecular scale.

Influence of Relative Humidity on AC Corona Discharge from Algae Attached on the Silicone Rubber

NASA Astrophysics Data System (ADS)

Sato, Daisuke; Hara, Yoshiaki; Kokufu, Morihide; Higashiyama, Yoshio

To make clear the influence of algae growth at the surface of a polymer insulator in a practical transmission line, the characteristics of ac corona discharge from an aggregate algae particle were investigated. The aggregate algae particle was made of Protococcus viridis. Corona onset voltage from an aggregate algae particle was decreased as relative humidity increased. Under the condition of relatively higher relative humidity, luminous channel of corona discharge became more strongly and the number of corona pulses in the current waveform was increased. For an aggregate algae particle contaminated with sea salt including MgCl2, corona onset voltage decreased drastically at relative humidity above 40%. This property would result from deliquescence of MgCl2. Corona discharge was strongly affected by existence of MgCl2 in an aggregate algae particle. Surface resistance of algae attached to the surface of the silicone rubber sheet decreased in fourth figures for relative humidity from 20 to 90%. Therefore, the existence of algae on the polymer insulator inevitably affects the electric property and the surface property of the polymer insulator.

O-GlcNAc modification blocks the aggregation and toxicity of the protein α-synuclein associated with Parkinson's disease

NASA Astrophysics Data System (ADS)

Marotta, Nicholas P.; Lin, Yu Hsuan; Lewis, Yuka E.; Ambroso, Mark R.; Zaro, Balyn W.; Roth, Maxwell T.; Arnold, Don B.; Langen, Ralf; Pratt, Matthew R.

2015-11-01

Several aggregation-prone proteins associated with neurodegenerative diseases can be modified by O-linked N-acetyl-glucosamine (O-GlcNAc) in vivo. One of these proteins, α-synuclein, is a toxic aggregating protein associated with synucleinopathies, including Parkinson's disease. However, the effect of O-GlcNAcylation on α-synuclein is not clear. Here, we use synthetic protein chemistry to generate both unmodified α-synuclein and α-synuclein bearing a site-specific O-GlcNAc modification at the physiologically relevant threonine residue 72. We show that this single modification has a notable and substoichiometric inhibitory effect on α-synuclein aggregation, while not affecting the membrane binding or bending properties of α-synuclein. O-GlcNAcylation is also shown to affect the phosphorylation of α-synuclein in vitro and block the toxicity of α-synuclein that was exogenously added to cells in culture. These results suggest that increasing O-GlcNAcylation may slow the progression of synucleinopathies and further support a general function for O-GlcNAc in preventing protein aggregation.

Inhibition of the aggregation of lactoferrin and (-)-epigallocatechin gallate in the presence of polyphenols, oligosaccharides, and collagen peptide.

PubMed

Yang, Wei; Liu, Fuguo; Xu, Chenqi; Sun, Cuixia; Yuan, Fang; Gao, Yanxiang

2015-05-27

The aggregation of lactoferrin and (-)-epigallocatechin gallate (EGCG) was inhibited by polyphenols, oligosaccharides, and collagen peptide in this study. Polyphenols, oligosaccharides, or collagen peptide can effectively prevent the formation of lactoferrin-EGCG aggregates, respectively. The addition sequence of lactoferrin, polyphenols (oligosaccharides or collagen peptide) and EGCG can affect the turbidity and particle size of the ternary complexes in the buffer solution; however, it hardly affected the ζ-potential and fluorescence characteristics. With either positive or negative charge, polyphenols and collagen peptide disrupted the formation of lactoferrin-EGCG aggregate mainly through the mechanism of its competition with EGCG molecules which surrounded the lactoferrin molecule surface with weaker binding affinities, forming polyphenols or a collagen peptide-lactoferrin-EGCG ternary complex; for neutral oligosaccharides, the ternary complex was generated mainly through steric effects, accompanied by a change in the lactoferrin secondary structure induced by gallic acid, chlorogenic acid, and xylo-oligosaccharide. Polyphenols, oligosaccharides, or collagen peptide restraining the formation of lactoferrin-EGCG aggregate could be applied in the design of clear products in the food, pharmaceutical, and cosmetic industries.

Aggregation behavior of sodium lauryl ether sulfate with a positively bicharged organic salt and effects of the mixture on fluorescent properties of conjugated polyelectrolytes.

PubMed

Tang, Yongqiang; Liu, Zhang; Zhu, Linyi; Han, Yuchun; Wang, Yilin

2015-02-24

The aggregation behavior of anionic single-chain surfactant sodium lauryl ether sulfate containing three ether groups (SLE3S) with positively bicharged organic salt 1,2-bis(2-benzylammoniumethoxy)ethane dichloride (BEO) has been investigated in aqueous solution, and the effects of the BEO/SLE3S aggregate transitions on the fluorescent properties of anionic conjugated polyelectrolyte MPS-PPV with a larger molecular weight and cationic conjugated oligoelectrolyte DAB have been evaluated. Without BEO, SLE3S does not affect the fluorescent properties of MPS-PPV and only affects the fluorescent properties of DAB at a higher SLE3S concentration. With the addition of BEO, SLE3S and BEO form gemini-like surfactant (SLE3S)2-BEO. When the BEO/SLE3S molar ratio is fixed at 0.25, with increasing the BEO/SLE3S concentration, the BEO/SLE3S mixture forms large, loosely arranged aggregates and then transforms to closely packed spherical aggregates and finally to long thread-like micelles. The photoluminescence (PL) intensity of MPS-PPV varies with the morphologies of the BEO/SLE3S aggregates, while the PL intensity of DAB is almost independent of the aggregate morphologies. The results demonstrate that gemini-like surfactants formed through intermolecular interactions can effectively adjust the fluorescent properties of conjugated polyelectrolytes.

Polyhydroxylated [60]fullerene binds specifically to functional recognition sites on a monomeric and a dimeric ubiquitin

NASA Astrophysics Data System (ADS)

Zanzoni, Serena; Ceccon, Alberto; Assfalg, Michael; Singh, Rajesh K.; Fushman, David; D'Onofrio, Mariapina

2015-04-01

The use of nanoparticles (NPs) in biomedical applications requires an in-depth understanding of the mechanisms by which NPs interact with biomolecules. NPs associating with proteins may interfere with protein-protein interactions and affect cellular communication pathways, however the impact of NPs on biomolecular recognition remains poorly characterized. In this respect, particularly relevant is the study of NP-induced functional perturbations of proteins implicated in the regulation of key biochemical pathways. Ubiquitin (Ub) is a prototypical protein post-translational modifier playing a central role in numerous essential biological processes. To contribute to the understanding of the interactions between this universally distributed biomacromolecule and NPs, we investigated the adsorption of polyhydroxylated [60]fullerene on monomeric Ub and on a minimal polyubiquitin chain in vitro at atomic resolution. Site-resolved chemical shift and intensity perturbations of Ub's NMR signals, together with 15N spin relaxation rate changes, exchange saturation transfer effects, and fluorescence quenching data were consistent with the reversible formation of soluble aggregates incorporating fullerenol clusters. The specific interaction epitopes were identified, coincident with functional recognition sites in a monomeric and lysine48-linked dimeric Ub. Fullerenol appeared to target the open state of the dynamic structure of a dimeric Ub according to a conformational selection mechanism. Importantly, the protein-NP association prevented the enzyme-catalyzed synthesis of polyubiquitin chains. Our findings provide an experiment-based insight into protein/fullerenol recognition, with implications in functional biomolecular communication, including regulatory protein turnover, and for the opportunity of therapeutic intervention in Ub-dependent cellular pathways.The use of nanoparticles (NPs) in biomedical applications requires an in-depth understanding of the mechanisms by which NPs interact with biomolecules. NPs associating with proteins may interfere with protein-protein interactions and affect cellular communication pathways, however the impact of NPs on biomolecular recognition remains poorly characterized. In this respect, particularly relevant is the study of NP-induced functional perturbations of proteins implicated in the regulation of key biochemical pathways. Ubiquitin (Ub) is a prototypical protein post-translational modifier playing a central role in numerous essential biological processes. To contribute to the understanding of the interactions between this universally distributed biomacromolecule and NPs, we investigated the adsorption of polyhydroxylated [60]fullerene on monomeric Ub and on a minimal polyubiquitin chain in vitro at atomic resolution. Site-resolved chemical shift and intensity perturbations of Ub's NMR signals, together with 15N spin relaxation rate changes, exchange saturation transfer effects, and fluorescence quenching data were consistent with the reversible formation of soluble aggregates incorporating fullerenol clusters. The specific interaction epitopes were identified, coincident with functional recognition sites in a monomeric and lysine48-linked dimeric Ub. Fullerenol appeared to target the open state of the dynamic structure of a dimeric Ub according to a conformational selection mechanism. Importantly, the protein-NP association prevented the enzyme-catalyzed synthesis of polyubiquitin chains. Our findings provide an experiment-based insight into protein/fullerenol recognition, with implications in functional biomolecular communication, including regulatory protein turnover, and for the opportunity of therapeutic intervention in Ub-dependent cellular pathways. Electronic supplementary information (ESI) available: Experimental details. Fig. S1. Characterization of fullerenol by dynamic light scattering. Fig. S2. Size-exclusion chromatography. Fig. S3. 15N R1 spin relaxation rates of Ub and Ub2 upon subsequent additions of fullerenol. See DOI: 10.1039/c5nr00539f

Spatial pattern formation of microbes at the soil microscale affect soil C and N turnover in an individual-based microbial community model

NASA Astrophysics Data System (ADS)

Kaiser, Christina; Evans, Sarah; Dieckmann, Ulf; Widder, Stefanie

2016-04-01

At the μm-scale, soil is a highly structured and complex environment, both in physical as well as in biological terms, characterized by non-linear interactions between microbes, substrates and minerals. As known from mathematics and theoretical ecology, spatial structure significantly affects the system's behaviour by enabling synergistic dynamics, facilitating diversity, and leading to emergent phenomena such as self-organisation and self-regulation. Such phenomena, however, are rarely considered when investigating mechanisms of microbial soil organic matter turnover. Soil organic matter is the largest terrestrial reservoir for organic carbon (C) and nitrogen (N) and plays a pivotal role in global biogeochemical cycles. Still, the underlying mechanisms of microbial soil organic matter buildup and turnover remain elusive. We explored mechanisms of microbial soil organic matter turnover using an individual-based, stoichiometrically and spatially explicit computer model, which simulates the microbial de-composer system at the soil microscale (i.e. on a grid of 100 x 100 soil microsites). Soil organic matter dynamics in our model emerge as the result of interactions among individual microbes with certain functional traits (f.e. enzyme production rates, growth rates, cell stoichiometry) at the microscale. By degrading complex substrates, and releasing labile substances microbes in our model continusly shape their environment, which in turn feeds back to spatiotemporal dynamics of the microbial community. In order to test the effect of microbial functional traits and organic matter input rate on soil organic matter turnover and C and N storage, we ran the model into steady state using continuous inputs of fresh organic material. Surprisingly, certain parameter settings that induce resource limitation of microbes lead to regular spatial pattern formation (f.e. moving spiral waves) of microbes and substrate at the μm-scale at steady-state. The occurrence of these pattern can be explained by the Turing mechanism. These pattern formation had strong consequences for process rates, as well as for C and N storage in the soil at the steady state: Scenarios that exhibited pattern formation were generally associated with higher C storage at steady state compared to those without pattern formation (i.e. at non-limiting conditions for microbes). Moreover, pattern formation lead to a spatial decoupling of C and N turnover processes, and to a spatial decoupling of microbial N mineralization and N immobilization. Taken together, our theoretical analysis shows that self-organisation may be a feature of the soil decomposer system, with consequences for process rates of microbial C and N turnover. Pattern formation through spatial self-organization, which has been observed on larger spatial scales in other resource-limited communities (e.g., vegetation patterns in arid or wetland eco-systems), may also occur at the soil microscale, leaving its mark on the soil's storage capacity for C and N.

α- and β-Proteobacteria Control the Consumption and Release of Amino Acids on Lake Snow Aggregates

PubMed Central

Schweitzer, Bernhard; Huber, Ingrid; Amann, Rudolf; Ludwig, Wolfgang; Simon, Meinhard

2001-01-01

We analyzed the composition of aggregate (lake snow)-associated bacterial communities in Lake Constance from 1994 until 1996 between a depth of 25 m and the sediment surface at 110 m by fluorescent in situ hybridization with rRNA-targeted oligonucleotide probes of various specificity. In addition, we experimentally examined the turnover of dissolved amino acids and carbohydrates together with the microbial colonization of aggregates formed in rolling tanks in the lab. Generally, between 40 and more than 80% of the microbes enumerated by DAPI staining (4′,6′-diamidino-2-phenylindole) were detected as Bacteria by the probe EUB338. At a depth of 25 m, 10.5% ± 7.9% and 14.2% ± 10.2% of the DAPI cell counts were detected by probes specific for α- and β-Proteobacteria. These proportions increased to 12.0% ± 3.3% and 54.0% ± 5.9% at a depth of 50 m but decreased again at the sediment surface at 110 m to 2.7% ± 1.4% and 41.1% ± 8.4%, indicating a clear dominance of β-Proteobacteria at depths of 50 and 110 m, where aggregates have an age of 3 to 5 and 8 to 11 days, respectively. From 50 m to the sediment surface, cells detected by a Cytophaga/Flavobacteria-specific probe (CF319a) comprised increasing proportions up to 18% of the DAPI cell counts. γ-Proteobacteria always comprised minor proportions of the aggregate-associated bacterial community. Using only two probes highly specific for clusters of bacteria closely related to Sphingomonas species and Brevundimonas diminuta, we identified between 16 and 60% of the α-Proteobacteria. In addition, with three probes highly specific for close relatives of the β-Proteobacteria Duganella zoogloeoides (formerly Zoogloea ramigera), Acidovorax facilis, and Hydrogenophaga palleroni, bacteria common in activated sludge, 42 to 70% of the β-Proteobacteria were identified. In the early phase (<20 h) of 11 of the 15 experimental incubations of aggregates, dissolved amino acids were consumed by the aggregate-associated bacteria from the surrounding water. This stage was followed by a period of 1 to 3 days during which dissolved amino acids were released into the surrounding water, paralleled by an increasing dominance of β-Proteobacteria. Hence, our results show that lake snow aggregates are inhabited by a community dominated by a limited number of α- and β-Proteobacteria, which undergo a distinct succession. They successively decompose the amino acids bound in the aggregates and release substantial amounts into the surrounding water during aging and sinking. PMID:11157226

48 CFR 31.001 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... future conditions affecting pension cost; e.g., mortality rate, employee turnover, compensation levels... accounting period and are valued as they accrue; i.e., based on the services performed by each employee in... the present value of the units of benefit deemed to be credited to employees for service in that...

Molecular mechanisms underlying the actions of dietary factors on the skeleton

USDA-ARS?s Scientific Manuscript database

This book chapter summarizes the current state of knowledge on molecular mechanisms whereby nutritional status and dietary factors found in fruits, vegetables, and grains affect bone turnover and skeletal quality. The Wnt-beta catenin and bone morphogenic protein (BMP) pathways in osteoblast bone ce...

Effects of recombinant protein misfolding and aggregation on bacterial membranes.

PubMed

Ami, D; Natalello, A; Schultz, T; Gatti-Lafranconi, P; Lotti, M; Doglia, S M; de Marco, A

2009-02-01

The expression of recombinant proteins is known to induce a metabolic rearrangement in the host cell. We used aggregation-sensitive model systems to study the effects elicited in Escherichia coli cells by the aggregation of recombinant glutathione-S-transferase and its fusion with the green fluorescent protein that, according to the expression conditions, accumulate intracellularly as soluble protein, or soluble and insoluble aggregates. We show that the folding state of the recombinant protein and the complexity of the intracellular aggregates critically affect the cell response. Specifically, protein misfolding and aggregation induce changes in specific host proteins involved in lipid metabolism and oxidative stress, a reduction in the membrane permeability, as well as a rearrangement of its lipid composition. The temporal evolution of the host cell response and that of the aggregation process pointed out that the misfolded protein and soluble aggregates are responsible for the membrane modifications and the changes in the host protein levels. Interestingly, native recombinant protein and large insoluble aggregates do not seem to activate stress markers and membrane rearrangements.

Using Human iPSC-Derived Neurons to Model TAU Aggregation

PubMed Central

Verheyen, An; Diels, Annick; Dijkmans, Joyce; Oyelami, Tutu; Meneghello, Giulia; Mertens, Liesbeth; Versweyveld, Sofie; Borgers, Marianne; Buist, Arjan; Peeters, Pieter; Cik, Miroslav

2015-01-01

Alzheimer’s disease and frontotemporal dementia are amongst the most common forms of dementia characterized by the formation and deposition of abnormal TAU in the brain. In order to develop a translational human TAU aggregation model suitable for screening, we transduced TAU harboring the pro-aggregating P301L mutation into control hiPSC-derived neural progenitor cells followed by differentiation into cortical neurons. TAU aggregation and phosphorylation was quantified using AlphaLISA technology. Although no spontaneous aggregation was observed upon expressing TAU-P301L in neurons, seeding with preformed aggregates consisting of the TAU-microtubule binding repeat domain triggered robust TAU aggregation and hyperphosphorylation already after 2 weeks, without affecting general cell health. To validate our model, activity of two autophagy inducers was tested. Both rapamycin and trehalose significantly reduced TAU aggregation levels suggesting that iPSC-derived neurons allow for the generation of a biologically relevant human Tauopathy model, highly suitable to screen for compounds that modulate TAU aggregation. PMID:26720731

Responses of soil carbon turnover rates to pyrogenic carbon additions to a forest soil of Sierra Nevada, California: effects of pyrolysis temperature and soil depth

NASA Astrophysics Data System (ADS)

Santos, F.; Bird, J. A.; Berhe, A. A.

2017-12-01

Pyrogenic organic carbon (PyC) is a heterogenous mixture of thermally altered residues, ranging from slightly charred plant biomass to soot. Despite its apparent stability in soils, PyC has been reported to either increase or decrease (priming effect, PE), or have no effect on the mineralization rates of native soil organic matter (SOM), highlighting our limited knowledge on the mechanisms driving PyC-induced PE. Little is known about how PyC's pyrolysis temperature, and soil depth (surface versus subsurface) affect the direction of PE. To address this gap knowledge, we conducted from a 1-year laboratory incubation study aimed to investigate the interactive effects of pyrolysis temperature and soil depth on the mineralization rates of native SOM in fine-loamy, temperate forest soil that received additions of dual-labeled 13C and 15N jack pine pyrogenic organic matter produced at 300oC (PyC300) and 450oC (PyC450). Soil and PyC mixture were incubated in surface (0-10 cm) and subsurface (50-70 cm) forest soils in the dark at 55% soil field capacity and 25oC. Losses of native SOM as 13CO2 were measured periodically from the 13C-labeled PyC, and native (unlabeled) SOM during the incubation study using a Thermo Scientific GasBench interfaced to a Delta V Plus isotope ratio mass spectrometer. In surface soils, the addition of PyC300 decreased the turnover rates of native C relative to control treatments, whereas PyC400 had no effect on native C turnover rates. In subsurface soils, neither PyC300 nor PyC400 additions affected native C turnover rates. Our preliminary findings suggest that pyrolysis temperature is an important factor driving the persistence of soil C in Sierra Nevada forest soils.

The Hypothalamic-Pituitary-Adrenal Axis and Serotonin Metabolism in Individual Brain Nuclei of Mice with Genetic Disruption of the NK1 Receptor Exposed to Acute Stress.

PubMed

Culman, Juraj; Mühlenhoff, Stephan; Blume, Annegret; Hedderich, Jürgen; Lützen, Ulf; Hunt, Stephen P; Rupniak, Nadia M J; Zhao, Yi

2018-06-15

Mice lacking the substance P (SP) neurokinin-1 (NK1) receptor (NK1R-/-mice) were used to investigate whether SP affects serotonin (5-HT) function in the brain and to assess the effects of acute immobilisation stress on the hypothalamic-pituitary-adrenocortical (HPA) axis and 5-HT turnover in individual brain nuclei. Basal HPA activity and the expression of hypothalamic corticotropin-releasing hormone (CRH) in wild-type (WT)- and NK1R-/- mice were identical. Stress-induced increases in plasma ACTH concentration were considerably higher in NK1R-/- mice than in WT mice while corticosterone concentrations were equally elevated in both mouse lines. Acute stress did not alter the expression of CRH. In the dorsal raphe nucleus (DRN), basal 5-HT turnover was increased in NK1R-/- mice and a 15 min stress further magnified 5-HT utilisation in this region. In the frontoparietal cortex, medial prefrontal cortex, central nucleus of amygdala, and the hippocampal CA1 region, stress increased 5-HT and/or 5-hydroxyindoleacetic acid (5-HIAA) concentrations to a similar extent in WT and NK1R-/- mice. 5-HT turnover in the hypothalamic paraventricular nucleus was not affected by stress, but stress induced similar increases in 5-HT and 5-HIAA in the ventromedial and dorsomedial hypothalamic nuclei in WT and NK1R-/- mice. Our findings indicate that NK1 receptor activation suppresses ACTH release during acute stress but does not exert sustained inhibition of the HPA axis. Genetic deletion of the NK1 receptor accelerates 5-HT turnover in DRN under basal and stress conditions. No differences between the responses of serotonergic system to acute stress in WT and NK1R-/- mice occur in forebrain nuclei linked to the regulation of anxiety and neuroendocrine stress responses.

PTH (1-34) affects bone turnover governed by osteocytes exposed to fluoride.

PubMed

Yu, Xiuhua; Yu, Haolan; Jiang, Ningning; Zhang, Xiuyun; Zhang, Mengmeng; Xu, Hui

2018-05-15

Exposure to fluoride from environmental sources remains an overlooked, but serious public health risk. In this study, we looked into the role osteocytes play on the mechanism underlying fluoride induced osteopathology. We analyzed bone formation and resorption related genes generated by osteocytes that were exposed to varied doses of fluoride with and without PTH in vitro. Correspondingly, osteogenesis and osteoclastogenesis related genes were also investigated in rats exposed to fluoride for 8 weeks, and the PTH(1-34)was applied at the last 3 weeks to observe its role in regulating bone turnover upon fluoride treatment. The data in vitro indicated that fluoride treatment inhibited Sost expression of mRNA and protein and stimulated RANKL mRNA protein expression as well as the RANKL/OPG ratio in the primary osteocytes. Single PTH treatment played the similar role on expression of these genes and proteins. The PTH combined administration enhanced the action of fluoride treatment on RNAKL/OPG and SOST/Sclerostin. The up-regulation of RANKL and decreasing of Sost induced by fluoride and/or PTH treatment was validated in vivo and suggests that osteocytes are a major source of RANKL and Sost, both of which play essential roles in fluoride affecting osteogenesis and osteoclastogenesis. Expression of Wnt/β-catenin was up-regulated in both in vitro osteocytes treated with high dose of fluoride and bone tissue of rats in the presence of fluoride and PTH. In vivo, fluoride and single PTH stimulated bone turnover respectively, furthermore, PTH combined with low dose of fluoride treatment reinforced the osteogenesis and osteoclastogenesis genes expression, however, co-treatment of PTH reversed the effect of high dose of fluoride on osteogenesis and osteoclastogenensis related factors. In conclusion, this study demonstrated that osteocytes play a key role in fluoride activated bone turnover, and PTH participates in the process of fluoride modulating SOST/Sclerostin and RANKL expression. Copyright © 2018 Elsevier B.V. All rights reserved.

[Effects of hyposalinity in Thalassia testudinum (Hydrocharitaceae) from Parque Nacional Morrocoy, Venezuela].

PubMed

Pérez, D; Galindo, L

2000-12-01

The year 1996 had a high pluviosity in Morrocoy National Park (western coastal zone, Venezuela) and low salinity in December 1996 affected the seagrass beds, dominated by Thalassia testudinum. Patches without T. testudinum were observed in localities of the park that used to have very dense populations of this plant. Sampling was done at Las Luisas to determine leaf productivity, turnover rate, short shoot density and relative biomass of plant sections, in order to compare with data obtained in September 1996, previous to the event. Green leaves, roots and rhizomes were the most affected parts. Mean green leaf biomass decreased in January and February 1997 to 5% of the plant's total biomass; mean root biomass decreased in March to 40% and mean rhi zome biomass decreased in February to 30%. The density of the active short shoots decreased to a minimum in February, but in April it reached a value similar to that of September 1996. The density of the inactive short shoots decreased to a minimum in March, and they dissappeared in April, matching the increasing density of the active short shoots between these two months. In February 1997, 56% of the inactive short shoots showed evidence of leaf initiation. In January 1997 the leaf productivity and turnover rate values (2.72 +/- 0.35 g/m2/d and 2.15% leaf DW/d) were similar to the annual mean previously determined from Las Luisas (2.35 +/- 0.72 g/m2/d and 1.96% leaf DW/d). Nevertheless, the values of productivity and turnover rate detected at Las Luisas in April 1997 (4.88 +/- 2.14 g/m2/d and 4.66% leaf DW/d) were higher than those values previously reported for this location. In response to the mortality episode, the leaf productivity and turnover rate of T. testudinum increased and the leaf initiation was activated in the inactive short shoots.

Radiocesium distribution in aggregate-size fractions of cropland and forest soils affected by the Fukushima nuclear accident.

PubMed

Koarashi, Jun; Nishimura, Syusaku; Atarashi-Andoh, Mariko; Matsunaga, Takeshi; Sato, Tsutomu; Nagao, Seiya

2018-08-01

The Fukushima Daiichi nuclear power plant accident caused serious radiocesium ( 137 Cs) contamination in soils in a range of terrestrial ecosystems. It is well documented that the interaction of 137 Cs with soil constituents, particularly clay minerals, in surface soil layers exerts strong control on the behavior of this radionuclide in the environment; however, there is little understanding of how soil aggregation-the binding of soil particles together into aggregates-can affect the mobility and bioavailability of 137 Cs in soils. To explore this, soil samples were collected at seven sites under different land-use conditions in Fukushima and were separated into four aggregate-size fractions: clay-sized (<2 μm); silt-sized (2-20 μm); sand-sized (20-212 μm); and macroaggregates (212-2000 μm). The fractions were then analyzed for 137 Cs content and extractability and mineral composition. In forest soils, aggregate formation was significant, and 69%-83% of 137 Cs was associated with macroaggregates and sand-sized aggregates. In contrast, there was less aggregation in agricultural field soils, and approximately 80% of 137 Cs was in the clay- and silt-sized fractions. Across all sites, the 137 Cs extractability was higher in the sand-sized aggregate fractions than in the clay-sized fractions. Mineralogical analysis showed that, in most soils, clay minerals (vermiculite and kaolinite) were present even in the larger-sized aggregate fractions. These results demonstrate that larger-sized aggregates are a significant reservoir of potentially mobile and bioavailable 137 Cs in organic-rich (forest and orchard) soils. Our study suggests that soil aggregation reduces the mobility of particle-associated 137 Cs through erosion and resuspension and also enhances the bioavailability of 137 Cs in soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sunlight affects aggregation and deposition of graphene oxide in the aquatic environment.

EPA Science Inventory

In this study, we investigate the role of simulated sunlight on the physicochemical properties, aggregation, and deposition of graphene oxide (GO) in aquatic environments. Results show that light exposure under varied environmental conditions significantly impacts the physicochem...

Nitro-Assisted Brønsted Acid Catalysis: Application to a Challenging Catalytic Azidation.

PubMed

Dryzhakov, Marian; Hellal, Malik; Wolf, Eléna; Falk, Florian C; Moran, Joseph

2015-08-05

A cocatalytic effect of nitro compounds is described for the B(C6F5)3·H2O catalyzed azidation of tertiary aliphatic alcohols, enabling catalyst turnover for the first time and with a broad range of substrates. Kinetic investigations into this surprising effect reveal that nitro compounds induce a switch from first order concentration dependence in Brønsted acid to second order concentration dependence in Brønsted acid and second order dependence in the nitro compounds. Kinetic, electronic, and spectroscopic evidence suggests that higher order hydrogen-bonded aggregates of nitro compounds and acids are the kinetically competent Brønsted acid catalysts. Specific weak H-bond accepting additives may offer a new general approach to accelerating Brønsted acid catalysis in solution.

Dynamics of soil biogeochemical gas emissions shaped by remolded aggregate sizes and carbon configurations under hydration cycles.

PubMed

Ebrahimi, Ali; Or, Dani

2018-01-01

Changes in soil hydration status affect microbial community dynamics and shape key biogeochemical processes. Evidence suggests that local anoxic conditions may persist and support anaerobic microbial activity in soil aggregates (or in similar hot spots) long after the bulk soil becomes aerated. To facilitate systematic studies of interactions among environmental factors with biogeochemical emissions of CO 2 , N 2 O and CH 4 from soil aggregates, we remolded silt soil aggregates to different sizes and incorporated carbon at different configurations (core, mixed, no addition). Assemblies of remolded soil aggregates of three sizes (18, 12, and 6 mm) and equal volumetric proportions were embedded in sand columns at four distinct layers. The water table level in each column varied periodically while obtaining measurements of soil GHG emissions for the different aggregate carbon configurations. Experimental results illustrate that methane production required prolonged inundation and highly anoxic conditions for inducing measurable fluxes. The onset of unsaturated conditions (lowering water table) resulted in a decrease in CH 4 emissions while temporarily increasing N 2 O fluxes. Interestingly, N 2 O fluxes were about 80% higher form aggregates with carbon placement in center (anoxic) core compared to mixed carbon within aggregates. The fluxes of CO 2 were comparable for both scenarios of carbon sources. These experimental results highlight the importance of hydration dynamics in activating different GHG production and affecting various transport mechanisms about 80% of total methane emissions during lowering water table level are attributed to physical storage (rather than production), whereas CO 2 emissions (~80%) are attributed to biological activity. A biophysical model for microbial activity within soil aggregates and profiles provides a means for results interpretation and prediction of trends within natural soils under a wide range of conditions. © 2017 John Wiley & Sons Ltd.

Effect of cobalt ions on the interaction between macrophages and titanium.

PubMed

Pettersson, Mattias; Pettersson, Jean; Thorén, Margareta Molin; Johansson, Anders

2018-04-30

Inflammation and bone reduction around dental implants are described as peri-implantitis and can be caused by an inflammatory response against bacterial products and toxins. Titanium (Ti) forms aggregates with serum proteins, which activate and cause release of the cytokine interleukin (IL-1β) from human macrophages. It was hypothesized that cobalt (Co) ions can interact in the formation of pro-inflammatory aggregates, formed by titanium. To test this hypothesis, we differentiated THP-1 cells into macrophages and exposed them to Ti ions alone or in combination with Co ions to investigate if IL-1β release and cytotoxicity were affected. We also investigated aggregate formation, cell uptake and human biopsies with inductively coupled plasma atomic emission spectroscopy (ICP-AES) and electron microscopy. Co at a concentration of 100 µM neutralized the IL-1β release from human macrophages and affected the aggregate formation. The aggregates formed by Ti could be detected in the cytosol of macrophages. In the presence of Co, the Ti-induced aggregates were located in the cytosol of the cultured macrophages, but outside the lysosomal structures. It is concluded that Co can neutralize the Ti-induced activation and release of active IL-1β from human macrophages in vitro. Also, serum proteins are needed for the formation of metal-protein aggregates in cell medium. Furthermore, the structures of the aggregates as well as the localisation after cellular uptake differ if Co is present in a Ti solution. Phagocytized aggregates with a similar appearance seen in vitro with Ti present, were also visible in a sample from human peri-implant tissue. This article is protected by copyright. All rights reserved. © 2018 Wiley Periodicals, Inc.

Carbon-14 bomb pulse dating shows that tendinopathy is preceded by years of abnormally high collagen turnover.

PubMed

Heinemeier, Katja Maria; Schjerling, Peter; Øhlenschlæger, Tommy F; Eismark, Christian; Olsen, Jesper; Kjær, Michael

2018-03-23

Tendons are essential weight-bearing structures that are often affected by tendinopathy, which leads to pain and impaired mobility. In healthy Achilles tendons, no significant renewal of the weight-bearing collagen matrix seems to occur during adult life, but tendinopathy may lead to increased turnover. The carbon-14 ([ 14 C]) bomb pulse method was used to measure lifelong replacement rates of collagen in tendinopathic and healthy Achilles tendons (tendinopathic: n = 25, born 1937-72. Healthy: n = 10, born 1929-66). As expected, the healthy tendon collagen had not been replaced during adulthood, but in tendinopathic tendon, a substantial renewal had occurred. Modeling of the [ 14 C] data suggested that one half of the collagen in tendinopathic matrix had undergone continuous slow turnover for years before the presentation of symptoms. This finding allows for a new concept in tendon pathogenesis because it suggests that either the symptoms of tendinopathy represent a late phase of a very prolonged disease process, or an abnormally high collagen exchange could be a risk factor for tendon disorders rather than being a result of disease.-Heinemeier, K. M., Schjerling, P., Øhlenschlæger, T. F., Eismark, C., Olsen, J., Kjær, M. Carbon-14 bomb pulse dating shows that tendinopathy is preceded by years of abnormally high collagen turnover.

The importance of social exchange to nurses and nurse assistants: impact on retention factors.

PubMed

Trybou, Jeroen; De Pourcq, Kaat; Paeshuyse, Michel; Gemmel, Paul

2014-07-01

The purpose of this study was to test the norm of reciprocity by examining relationships between perceived organisational support (POS), the quality of leader-member exchange (LMX) and psychological contract breach (PCB) and important nurse retention factors identified in the literature. A major cause of turnover among nurses is related to unsatisfying workplaces. Previous research, mainly outside the nursing setting, found that social exchange affects employees' work-related attitudes. A cross-sectional survey was conducted on 217 nurses and nursing assistants to test and refine a model linking POS, LMX, PCB with job satisfaction, trust and turnover intentions. Hierarchical multiple linear regression revealed that POS, PCB and LMX explained significant variance in all three retention factors: job satisfaction (adjusted R² = 0.502), trust (adjusted R² = 0.462) and turnover intentions (adjusted R² = 0.196). POS and PCB predicted most strongly job satisfaction (P < 0.001) and trust (P < 0.001 and P < 0.01, respectively). LMX predicted most strongly intention to leave (P < 0.01). In our study, POS, the quality of LMX and PCB were strongly related to job satisfaction, trust and turnover intentions. Nursing managers and leaders should recognize the importance of social exchange within their organisation to build trust, satisfy and retain scarce nurses and nursing assistants. © 2013 John Wiley & Sons Ltd.

Gender Differences in Perceptions of Resources and Turnover Intentions of Work-Linked Couples in Masculine Occupations.

PubMed

Huffman, Ann Hergatt; Olson, Kristine J

2017-10-01

Employees in work-linked marriages have spouses that share the same family and the same workplace and/or occupation. Whereas, in recent years, there has been increasingly more research on dual-career marriages (i.e. both spouses work, but not necessarily at the same workplace and/or occupation), there has been very little research on work-linked marriages. The current study focuses on work resources (i.e. family supportive supervisor behaviour and job control) as key mediating processes that explain the effect of gender on turnover intentions among work-linked employees in masculine occupations (i.e. military). Investigating gender differences is important because, compared with men, women are more likely to be in work-linked marriages and to leave their jobs. Based on role theory and conservation of resource theory, we predicted that gender was related to turnover intentions, and this relationship would be mediated by key explanatory variables (i.e. family supportive supervisor behaviours, job control and psychological distress). Mediation analyses, conducted on a sample of men and women in work-linked marriages (n = 309), provide support for the hypothesized model. These findings offer guidance for understanding gender differences among work-linked employees in masculine occupations, and how these differences can affect important outcomes such as turnover intentions. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The effects of proximal withdrawal states on job attitudes, job searching, intent to leave, and employee turnover.

PubMed

Li, Junchao Jason; Lee, Thomas W; Mitchell, Terence R; Hom, Peter W; Griffeth, Rodger W

2016-10-01

We present the first major test of proximal withdrawal states theory (PWST; Hom, Mitchell, Lee, & Griffeth, 2012). In addition, we develop and test new ideas to demonstrate how PWST improves our understanding and prediction of employee turnover. Across 2 studies, we corroborate that reluctant stayers (those who want to leave but have to stay) are similar to enthusiastic leavers (those who want to leave and can leave) in affective commitment, job satisfaction, and job embeddedness, and that reluctant leavers (those who want to stay but have to leave) are similar to enthusiastic stayers (those who want to stay and can stay) on these dimensions. We find that job satisfaction and job embeddedness more strongly influence the intent to leave and job search behavior for enthusiastic stayers and leavers than for reluctant stayers and leavers. More important, we show that for those experiencing low control over their preference for leaving or staying (i.e., reluctant stayers and leavers), traditional variables such as job satisfaction, job embeddedness, and intent to leave are poor predictors of their turnover behavior. We further demonstrate that focusing on enthusiastic stayers and leavers can significantly enhance the accuracy of job satisfaction, job embeddedness, and intent to leave for predicting actual employee turnover. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

The Role of Diacylglycerol Acyltransferase (DGAT) 1 and 2 in Cardiac Metabolism and Function.

PubMed

Roe, Nathan D; Handzlik, Michal K; Li, Tao; Tian, Rong

2018-03-21

It is increasingly recognized that synthesis and turnover of cardiac triglyceride (TG) play a pivotal role in the regulation of lipid metabolism and function of the heart. The last step in TG synthesis is catalyzed by diacylglycerol:acyltransferase (DGAT) which esterifies the diacylglycerol with a fatty acid. Mammalian heart has two DGAT isoforms, DGAT1 and DGAT2, yet their roles in cardiac metabolism and function remain poorly defined. Here, we show that inactivation of DGAT1 or DGAT2 in adult mouse heart results in a moderate suppression of TG synthesis and turnover. Partial inhibition of DGAT activity increases cardiac fatty acid oxidation without affecting PPARα signaling, myocardial energetics or contractile function. Moreover, coinhibition of DGAT1/2 in the heart abrogates TG turnover and protects the heart against high fat diet-induced lipid accumulation with no adverse effects on basal or dobutamine-stimulated cardiac function. Thus, the two DGAT isoforms in the heart have partially redundant function, and pharmacological inhibition of one DGAT isoform is well tolerated in adult hearts.

RBC-/Cr-51/ half-life and albumin turnover in growing Beagle dogs during chronic radial acceleration

NASA Technical Reports Server (NTRS)

Beckman, D. A.; Evans, J. W.; Oyama, J.

1979-01-01

The effects of chronic centrifugation on growing Beagle dogs exposed to -2 or -2.6 Gx on albumin and RBC turnover rates, albumin concentration and space, and total blood volume were determined and compared with caged and run control of animals. Albumin-(I-125) and autologous RBC-(Cr-51) preparations were injected into all dogs at day 82 of the centrifugation periods, and the disappearance curves were determined by successive bleedings of the animals over the next 35 d, during which the centrifugation was continued. There were no differences in albumin turnover rates or space. Two populations of RBCs were found in both centrifugated groups, one with a normal half-life of 27 + or - 1 S.E.M. d, and one with a significantly (p less than 0.01) shorter half-life of 15 + or - 2 S.E.M. d. An absolute polycythemia was also observed in both centrifuged groups. The results suggest that chronic centrifugation acts through some as-yet unknown mechanism to affect RBC population kinetics.

Terrestrial carbon turnover time constraints on future carbon cycle-climate feedback

NASA Astrophysics Data System (ADS)

Fan, N.; Carvalhais, N.; Reichstein, M.

2017-12-01

Understanding the terrestrial carbon cycle-climate feedback is essential to reduce the uncertainties resulting from the between model spread in prognostic simulations (Friedlingstein et al., 2006). One perspective is to investigate which factors control the variability of the mean residence times of carbon in the land surface, and how these may change in the future, consequently affecting the response of the terrestrial ecosystems to changes in climate as well as other environmental conditions. Carbon turnover time of the whole ecosystem is a dynamic parameter that represents how fast the carbon cycle circulates. Turnover time τ is an essential property for understanding the carbon exchange between the land and the atmosphere. Although current Earth System Models (ESMs), supported by GVMs for the description of the land surface, show a strong convergence in GPP estimates, but tend to show a wide range of simulated turnover times (Carvalhais, 2014). Thus, there is an emergent need of constraints on the projected response of the balance between terrestrial carbon fluxes and carbon stock which will give us more certainty in response of carbon cycle to climate change. However, the difficulty of obtaining such a constraint is partly due to lack of observational data on temporal change of terrestrial carbon stock. Since more new datasets of carbon stocks such as SoilGrid (Hengl, et al., 2017) and fluxes such as GPP (Jung, et al., 2017) are available, improvement in estimating turnover time can be achieved. In addition, previous study ignored certain aspects such as the relationship between τ and nutrients, fires, etc. We would like to investigate τ and its role in carbon cycle by combining observatinoal derived datasets and state-of-the-art model simulations.

Impact of job satisfaction components on intent to leave and turnover for hospital-based nurses: a review of the research literature.

PubMed

Coomber, Billie; Barriball, K Louise

2007-02-01

The United Kingdom (UK), alongside other industrialised countries, is experiencing a shortage of nurses partly due to low retention rates. Job satisfaction has been highlighted as a contributing factor to intent to leave and turnover, yet this is a complex area with many elements affecting its measurement. The aim of this paper is to explore the impact of job satisfaction components on intent to leave and turnover for hospital-based nurses in order to identify the most influential factors. To achieve this, a systematic search of the literature was undertaken to identify relevant international research. Three databases (i.e. BNI, CINAHL and PsychInfo) were utilised, resulting in nine articles that met the inclusion criteria. Four recurrent themes were identified in the literature: leadership, educational attainment, pay and stress. The key findings suggest that stress and leadership issues continue to exert influence on dissatisfaction and turnover for nurses. Level of education achieved and pay were found to be associated with job satisfaction, although the results for these factors were not consistent. Investigating possible changes over time in sources of dissatisfaction revealed that factors related to the work environment rather than individual or demographic factors were still of most importance to nurses' turnover intentions. The differences found to occur across work settings necessitates analysis of job satisfaction at ward level, and the contribution of qualitative methods to develop more detailed insight is emphasised. The inconsistent findings over time associated with the effects of educational attainment and pay on intent to leave suggest that it is imperative that sources of job satisfaction are reassessed in the light of ongoing changes.

Ground Layer Plant Species Turnover and Beta Diversity in Southern-European Old-Growth Forests

PubMed Central

Sabatini, Francesco Maria; Burrascano, Sabina; Tuomisto, Hanna; Blasi, Carlo

2014-01-01

Different assembly processes may simultaneously affect local-scale variation of species composition in temperate old-growth forests. Ground layer species diversity reflects chance colonization and persistence of low-dispersal species, as well as fine-scale environmental heterogeneity. The latter depends on both purely abiotic factors, such as soil properties and topography, and factors primarily determined by overstorey structure, such as light availability. Understanding the degree to which plant diversity in old-growth forests is associated with structural heterogeneity and/or to dispersal limitation will help assessing the effectiveness of silvicultural practices that recreate old-growth patterns and structures for the conservation or restoration of plant diversity. We used a nested sampling design to assess fine-scale species turnover, i.e. the proportion of species composition that changes among sampling units, across 11 beech-dominated old-growth forests in Southern Europe. For each stand, we also measured a wide range of environmental and structural variables that might explain ground layer species turnover. Our aim was to quantify the relative importance of dispersal limitation in comparison to that of stand structural heterogeneity while controlling for other sources of environmental heterogeneity. For this purpose, we used multiple regression on distance matrices at the within-stand extent, and mixed effect models at the extent of the whole dataset. Species turnover was best predicted by structural and environmental heterogeneity, especially by differences in light availability and in topsoil nutrient concentration and texture. Spatial distances were significant only in four out of eleven stands with a relatively low explanatory power. This suggests that structural heterogeneity is a more important driver of local-scale ground layer species turnover than dispersal limitation in southern European old-growth beech forests. PMID:24748155

Biotic homogenization of three insect groups due to urbanization.

PubMed

Knop, Eva

2016-01-01

Cities are growing rapidly, thereby expected to cause a large-scale global biotic homogenization. Evidence for the homogenization hypothesis is mostly derived from plants and birds, whereas arthropods have so far been neglected. Here, I tested the homogenization hypothesis with three insect indicator groups, namely true bugs, leafhoppers, and beetles. In particular, I was interested whether insect species community composition differs between urban and rural areas, whether they are more similar between cities than between rural areas, and whether the found pattern is explained by true species turnover, species diversity gradients and geographic distance, by non-native or specialist species, respectively. I analyzed insect species communities sampled on birch trees in a total of six Swiss cities and six rural areas nearby. In all indicator groups, urban and rural community composition was significantly dissimilar due to native species turnover. Further, for bug and leafhopper communities, I found evidence for large-scale homogenization due to urbanization, which was driven by reduced species turnover of specialist species in cities. Species turnover of beetle communities was similar between cities and rural areas. Interestingly, when specialist species of beetles were excluded from the analyses, cities were more dissimilar than rural areas, suggesting biotic differentiation of beetle communities in cities. Non-native species did not affect species turnover of the insect groups. However, given non-native arthropod species are increasing rapidly, their homogenizing effect might be detected more often in future. Overall, the results show that urbanization has a negative large-scale impact on the diversity specialist species of the investigated insect groups. Specific measures in cities targeted at increasing the persistence of specialist species typical for the respective biogeographic region could help to stop the loss of biodiversity. © 2015 John Wiley & Sons Ltd.

Neuroforecasting Aggregate Choice

PubMed Central

Knutson, Brian; Genevsky, Alexander

2018-01-01

Advances in brain-imaging design and analysis have allowed investigators to use neural activity to predict individual choice, while emerging Internet markets have opened up new opportunities for forecasting aggregate choice. Here, we review emerging research that bridges these levels of analysis by attempting to use group neural activity to forecast aggregate choice. A survey of initial findings suggests that components of group neural activity might forecast aggregate choice, in some cases even beyond traditional behavioral measures. In addition to demonstrating the plausibility of neuroforecasting, these findings raise the possibility that not all neural processes that predict individual choice forecast aggregate choice to the same degree. We propose that although integrative choice components may confer more consistency within individuals, affective choice components may generalize more broadly across individuals to forecast aggregate choice. PMID:29706726

Increased Protein Maintains Nitrogen Balance during Exercise-Induced Energy Deficit

USDA-ARS?s Scientific Manuscript database

PURPOSE: This study examined how a high-protein diet affected nitrogen balance and protein turnover during an exercise-induced energy deficit. METHODS: Twenty-two men completed a 4-d (D1-4) baseline period (BL) of an energy balance diet while maintaining usual physical activity level, followed by 7 ...

Examining Factors Which Influence Expatriate Educator Turnover in International Schools Abroad

ERIC Educational Resources Information Center

Gomez, Franklyn Michael

2017-01-01

The purpose of this study is to determine factors affecting the departure of expatriate teachers and expatriate administrators from international schools. The sample for this study is expatriate administrators and expatriate teachers from schools associated with the Association for the Advancement of International Education (AAIE). Expatriate…

Retention Strategies for Reducing Voluntary Turnover in a Higher Education Institution

ERIC Educational Resources Information Center

Walker, Susan K.

2017-01-01

Employees who choose to leave employment cause significant challenges for organizations. Compounded challenges exist when employee retention strategies are not effective, affecting job satisfaction and personnel replacement costs as the organization continues to lose qualified and valuable staff. This single case study, built on a psychological…

"Managed" Teacher Turnover: A Strategy for School Improvement

ERIC Educational Resources Information Center

Lewis, Jessica L.; London, Tim D.

2009-01-01

Given the negative implications of unmanaged teacher attrition for student learning and the potential of leadership actions to affect this dynamic, this article highlights the practices of one principal in the Chicago Public School (CPS) system who used teacher attrition to her school's advantage. Her actions reveal leadership practices that can…

Turnover of C99 is Controlled by a Crosstalk between ERAD and Ubiquitin-Independent Lysosomal Degradation in Human Neuroglioma Cells

PubMed Central

Bustamante, Hianara A.; Rivera-Dictter, Andrés; Cavieres, Viviana A.; Muñoz, Vanessa C.; González, Alexis; Lin, Yimo; Mardones, Gonzalo A.; Burgos, Patricia V.

2013-01-01

Alzheimer’s disease (AD) is characterized by the buildup of amyloid-β peptides (Aβ) aggregates derived from proteolytic processing of the β-amyloid precursor protein (APP). Amyloidogenic cleavage of APP by β-secretase/BACE1 generates the C-terminal fragment C99/CTFβ that can be subsequently cleaved by γ-secretase to produce Aβ. Growing evidence indicates that high levels of C99/CTFβ are determinant for AD. Although it has been postulated that γ-secretase-independent pathways must control C99/CTFβ levels, the contribution of organelles with degradative functions, such as the endoplasmic reticulum (ER) or lysosomes, is unclear. In this report, we investigated the turnover and amyloidogenic processing of C99/CTFβ in human H4 neuroglioma cells, and found that C99/CTFβ is localized at the Golgi apparatus in contrast to APP, which is mostly found in endosomes. Conditions that localized C99/CTFβ to the ER resulted in its degradation in a proteasome-dependent manner that first required polyubiquitination, consistent with an active role of the ER associated degradation (ERAD) in this process. Furthermore, when proteasomal activity was inhibited C99/CTFβ was degraded in a chloroquine (CQ)-sensitive compartment, implicating lysosomes as alternative sites for its degradation. Our results highlight a crosstalk between degradation pathways within the ER and lysosomes to avoid protein accumulation and toxicity. PMID:24376644

Turnover of C99 is controlled by a crosstalk between ERAD and ubiquitin-independent lysosomal degradation in human neuroglioma cells.

PubMed

Bustamante, Hianara A; Rivera-Dictter, Andrés; Cavieres, Viviana A; Muñoz, Vanessa C; González, Alexis; Lin, Yimo; Mardones, Gonzalo A; Burgos, Patricia V

2013-01-01

Alzheimer's disease (AD) is characterized by the buildup of amyloid-β peptides (Aβ) aggregates derived from proteolytic processing of the β-amyloid precursor protein (APP). Amyloidogenic cleavage of APP by β-secretase/BACE1 generates the C-terminal fragment C99/CTFβ that can be subsequently cleaved by γ-secretase to produce Aβ. Growing evidence indicates that high levels of C99/CTFβ are determinant for AD. Although it has been postulated that γ-secretase-independent pathways must control C99/CTFβ levels, the contribution of organelles with degradative functions, such as the endoplasmic reticulum (ER) or lysosomes, is unclear. In this report, we investigated the turnover and amyloidogenic processing of C99/CTFβ in human H4 neuroglioma cells, and found that C99/CTFβ is localized at the Golgi apparatus in contrast to APP, which is mostly found in endosomes. Conditions that localized C99/CTFβ to the ER resulted in its degradation in a proteasome-dependent manner that first required polyubiquitination, consistent with an active role of the ER associated degradation (ERAD) in this process. Furthermore, when proteasomal activity was inhibited C99/CTFβ was degraded in a chloroquine (CQ)-sensitive compartment, implicating lysosomes as alternative sites for its degradation. Our results highlight a crosstalk between degradation pathways within the ER and lysosomes to avoid protein accumulation and toxicity.

CELL SURFACE IMMUNOGLOBULIN

PubMed Central

Vitetta, Ellen S.; Uhr, Jonathan W.

1974-01-01

A new method for the detection of cell surface immunoglobulin labeled with isotopic precursors is described. The method consists of the aggregation of surface Ig on cells with specific antibody (heterologous) and the subsequent removal of antigen-antibody complexes by the combination of high speed centrifugation and immunoprecipitation of remaining soluble complexes using antibody to the heterologous Ig. Using this method, the kinetics of appearance of cell surface Ig and its turnover were studied in murine splenocytes. The results suggest that cell surface Ig is synthesized and transported in the same manner as secretory Ig rather than being synthesized on the plasma membrane. The turnover of intracellular and cell surface Ig in lymphocytes is slow. In contrast, intracellular Ig in plasma cells is rapidly secreted and usually without a cell surface phase. Cell surface Ig was shown to be radiolabeled with [3H]glucosamine, -galactose, and -fucose. The proportion of cell surface to intracellular (nonsurface) Ig labeled with these precursors suggests the same sequence of addition of sugars to Ig destined to be on the surface of lymphocytes as with Ig which will be secreted by plasma cells. Results with this new method also confirm earlier conclusions based on experiments using cell surface iodination: 8S IgM is the predominant Ig on the surface of murine splenocytes and the molecule appears to be attached by its µ-chains. PMID:4829935

Kinetic regulation of coated vesicle secretion

PubMed Central

Foret, Lionel; Sens, Pierre

2008-01-01

The secretion of vesicles for intracellular transport often relies on the aggregation of specialized membrane-bound proteins into a coat able to curve cell membranes. The nucleation and growth of a protein coat is a kinetic process that competes with the energy-consuming turnover of coat components between the membrane and the cytosol. We propose a generic kinetic description of coat assembly and the formation of coated vesicles and discuss its implication to the dynamics of COP vesicles that traffic within the Golgi and with the endoplasmic reticulum. We show that stationary coats of fixed area emerge from the competition between coat growth and the recycling of coat components, in a fashion resembling the treadmilling of cytoskeletal filaments. We further show that the turnover of coat components allows for a highly sensitive switching mechanism between a quiescent and a vesicle producing membrane, upon a slowing down of the exchange kinetics. We claim that the existence of this switching behavior, also triggered by factors, such as the presence of cargo and variation of the membrane mechanical tension, allows for efficient regulation of vesicle secretion. We propose a model, supported by different experimental observations, in which vesiculation of secretory membranes is impaired by the energy-consuming desorption of coat proteins, until the presence of cargo or other factors triggers a dynamical switch into a vesicle producing state. PMID:18824695

Across species-pool aggregation alters grassland productivity and diversity.

PubMed

McKenna, Thomas P; Yurkonis, Kathryn A

2016-08-01

Plant performance is determined by the balance of intra- and interspecific neighbors within an individual's zone of influence. If individuals interact over smaller scales than the scales at which communities are measured, then altering neighborhood interactions may fundamentally affect community responses. These interactions can be altered by changing the number (species richness), abundances (species evenness), and positions (species pattern) of the resident plant species, and we aimed to test whether aggregating species at planting would alter effects of species richness and evenness on biomass production at a common scale of observation in grasslands. We varied plant species richness (2, 4, or 8 species and monocultures), evenness (0.64, 0.8, or 1.0), and pattern (planted randomly or aggregated in groups of four individuals) within 1 × 1 m plots established with transplants from a pool of 16 tallgrass prairie species and assessed plot-scale biomass production and diversity over the first three growing seasons. As expected, more species-rich plots produced more biomass by the end of the third growing season, an effect associated with a shift from selection to complementarity effects over time. Aggregating conspecifics at a 0.25-m scale marginally reduced biomass production across all treatments and increased diversity in the most even plots, but did not alter biodiversity effects or richness-productivity relationships. Results support the hypothesis that fine-scale species aggregation affects diversity by promoting species coexistence in this system. However, results indicate that inherent changes in species neighborhood relationships along grassland diversity gradients may only minimally affect community (meter) - scale responses among similarly designed biodiversity-ecosystem function studies. Given that species varied in their responses to local aggregation, it may be possible to use such species-specific results to spatially design larger-scale grassland communities to achieve desired diversity and productivity responses.

Chronic hindlimb suspension unloading markedly decreases turnover rates of skeletal and cardiac muscle proteins and adipose tissue triglycerides.

PubMed

Bederman, Ilya R; Lai, Nicola; Shuster, Jeffrey; Henderson, Leigh; Ewart, Steven; Cabrera, Marco E

2015-07-01

We previously showed that a single bolus of "doubly-labeled" water ((2)H2 (18)O) can be used to simultaneously determine energy expenditure and turnover rates (synthesis and degradation) of tissue-specific lipids and proteins by modeling labeling patterns of protein-bound alanine and triglyceride-bound glycerol (Bederman IR, Dufner DA, Alexander JC, Previs SF. Am J Physiol Endocrinol Metab 290: E1048-E1056, 2006). Using this novel method, we quantified changes in the whole body and tissue-specific energy balance in a rat model of simulated "microgravity" induced by hindlimb suspension unloading (HSU). After chronic HSU (3 wk), rats exhibited marked atrophy of skeletal and cardiac muscles and significant decrease in adipose tissue mass. For example, soleus muscle mass progressively decreased 11, 43, and 52%. We found similar energy expenditure between control (90 ± 3 kcal · kg(-1)· day(-1)) and hindlimb suspended (81 ± 6 kcal/kg day) animals. By comparing food intake (∼ 112 kcal · kg(-1) · day(-1)) and expenditure, we found that animals maintained positive calorie balance proportional to their body weight. From multicompartmental fitting of (2)H-labeling patterns, we found significantly (P < 0.005) decreased rates of synthesis (percent decrease from control: cardiac, 25.5%; soleus, 70.3%; extensor digitorum longus, 44.9%; gastrocnemius, 52.5%; and adipose tissue, 39.5%) and rates of degradation (muscles: cardiac, 9.7%; soleus, 52.0%; extensor digitorum longus, 27.8%; gastrocnemius, 37.4%; and adipose tissue, 50.2%). Overall, HSU affected growth of young rats by decreasing the turnover rates of proteins in skeletal and cardiac muscles and adipose tissue triglycerides. Specifically, we found that synthesis rates of skeletal and cardiac muscle proteins were affected to a much greater degree compared with the decrease in degradation rates, resulting in large negative balance and significant tissue loss. In contrast, we found a small decrease in adipose tissue triglyceride synthesis paired with a large decrease in degradation, resulting in smaller negative energy balance and loss of fat mass. We conclude that HSU in rats differentially affects turnover of muscle proteins vs. adipose tissue triglycerides. Copyright © 2015 the American Physiological Society.

Informed herbivore movement and interplant communication determine the effects of induced resistance in an individual-based model.

PubMed

Rubin, Ilan N; Ellner, Stephen P; Kessler, André; Morrell, Kimberly A

2015-09-01

1. Plant induced resistance to herbivory affects the spatial distribution of herbivores, as well as their performance. In recent years, theories regarding the benefit to plants of induced resistance have shifted from ideas of optimal resource allocation towards a more eclectic set of theories that consider spatial and temporal plant variability and the spatial distribution of herbivores among plants. However, consensus is lacking on whether induced resistance causes increased herbivore aggregation or increased evenness, as both trends have been experimentally documented. 2. We created a spatial individual-based model that can describe many plant-herbivore systems with induced resistance, in order to analyse how different aspects of induced resistance might affect herbivore distribution, and the total damage to a plant population, during a growing season. 3. We analyse the specific effects on herbivore aggregation of informed herbivore movement (preferential movement to less-damaged plants) and of information transfer between plants about herbivore attacks, in order to identify mechanisms driving both aggregation and evenness. We also investigate how the resulting herbivore distributions affect the total damage to plants and aggregation of damage. 4. Even, random and aggregated herbivore distributions can all occur in our model with induced resistance. Highest levels of aggregation occurred in the models with informed herbivore movement, and the most even distributions occurred when the average number of herbivores per plant was low. With constitutive resistance, only random distributions occur. Damage to plants was spatially correlated, unless plants recover very quickly from damage; herbivore spatial autocorrelation was always weak. 5. Our model and results provide a simple explanation for the apparent conflict between experimental results, indicating that both increased aggregation and increased evenness of herbivores can result from induced resistance. We demonstrate that information transfer from plants to herbivores, and from plants to neighbouring plants, can both be major factors in determining non-random herbivore distributions. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

The relationship between job satisfaction, burnout, and turnover intention among physicians from urban state-owned medical institutions in Hubei, China: a cross-sectional study.

PubMed

Zhang, Yimin; Feng, Xueshan

2011-09-24

Throughout China, a growing number of physicians are leaving or intending to depart from their organizations owing to job dissatisfaction. Little information is available about the role of occupational burnout in this association. We set out to analyze the relationship between job satisfaction, burnout, and turnover intention, and further to determine whether occupational burnout can serve as a mediator among Chinese physicians from urban state-owned medical institutions. A cross-sectional survey was carried out in March 2010 in Hubei Province, central China. The questionnaires assessed sociodemographic characteristics, job satisfaction, burnout, and turnover intention. The job satisfaction and occupational burnout instruments were obtained by modifying the Chinese Physicians' Job Satisfaction Questionnaire (CPJSQ) and the Chinese Maslach Burnout Inventory (CMBI), respectively. Such statistical methods as one-way ANOVA, Pearson correlation, GLM-univariate and structural equation modeling were used. Of the 1600 physicians surveyed, 1451 provided valid responses. The respondents had medium scores (3.18 +/-0.73) on turnover intention, in which there was significant difference among the groups from three urban areas with different development levels. Turnover intention, which significantly and negatively related to all job-satisfaction subscales, positively related to each subscale of burnout syndrome. Work environment satisfaction (b = -0.074, p < 0.01), job rewards satisfaction (b = -0.073, p < 0.01), organizational management satisfaction (b = -0.146, p < 0.01), and emotional exhaustion (b = 0.135, p < 0.01) were identified as significant direct predictors of the turnover intention of physicians, with 41.2% of the variance explained unitedly, under the control of sociodemographic variables, among which gender, age, and years of service were always significant. However, job-itself satisfaction no longer became significant, with the estimated parameter on job rewards satisfaction smaller after burnout syndrome variables were included. As congregated latent concepts, job satisfaction had both significant direct effects (gamma21 = -0.32, p < 0.01) and indirect effects (gamma11 × beta21 = -0.13, p < 0.01) through occupational burnout (62% explained) as a mediator on turnover intention (47% explained). Our study reveals that several, but not all dimensions of both job satisfaction and burnout syndrome are relevant factors affecting physicians' turnover intention, and there may be partial mediation effects of occupational burnout, mainly through emotional exhaustion, within the impact of job satisfaction on turnover intention. This suggests that enhancements in job satisfaction can be expected to reduce physicians' intentions to quit by the intermediary role of burnout as well as the direct path. It is hoped that these findings will offer some clues for health-sector managers to keep their physician resource motivated and stable.

The relationship between job satisfaction, burnout, and turnover intention among physicians from urban state-owned medical institutions in Hubei, China: a cross-sectional study

PubMed Central

2011-01-01

Background Throughout China, a growing number of physicians are leaving or intending to depart from their organizations owing to job dissatisfaction. Little information is available about the role of occupational burnout in this association. We set out to analyze the relationship between job satisfaction, burnout, and turnover intention, and further to determine whether occupational burnout can serve as a mediator among Chinese physicians from urban state-owned medical institutions. Methods A cross-sectional survey was carried out in March 2010 in Hubei Province, central China. The questionnaires assessed sociodemographic characteristics, job satisfaction, burnout, and turnover intention. The job satisfaction and occupational burnout instruments were obtained by modifying the Chinese Physicians' Job Satisfaction Questionnaire (CPJSQ) and the Chinese Maslach Burnout Inventory (CMBI), respectively. Such statistical methods as one-way ANOVA, Pearson correlation, GLM-univariate and structural equation modeling were used. Results Of the 1600 physicians surveyed, 1451 provided valid responses. The respondents had medium scores (3.18 +/-0.73) on turnover intention, in which there was significant difference among the groups from three urban areas with different development levels. Turnover intention, which significantly and negatively related to all job-satisfaction subscales, positively related to each subscale of burnout syndrome. Work environment satisfaction (b = -0.074, p < 0.01), job rewards satisfaction (b = -0.073, p < 0.01), organizational management satisfaction (b = -0.146, p < 0.01), and emotional exhaustion (b = 0.135, p < 0.01) were identified as significant direct predictors of the turnover intention of physicians, with 41.2% of the variance explained unitedly, under the control of sociodemographic variables, among which gender, age, and years of service were always significant. However, job-itself satisfaction no longer became significant, with the estimated parameter on job rewards satisfaction smaller after burnout syndrome variables were included. As congregated latent concepts, job satisfaction had both significant direct effects (gamma21 = -0.32, p < 0.01) and indirect effects (gamma11 × beta21 = -0.13, p < 0.01) through occupational burnout (62% explained) as a mediator on turnover intention (47% explained). Conclusions Our study reveals that several, but not all dimensions of both job satisfaction and burnout syndrome are relevant factors affecting physicians' turnover intention, and there may be partial mediation effects of occupational burnout, mainly through emotional exhaustion, within the impact of job satisfaction on turnover intention. This suggests that enhancements in job satisfaction can be expected to reduce physicians' intentions to quit by the intermediary role of burnout as well as the direct path. It is hoped that these findings will offer some clues for health-sector managers to keep their physician resource motivated and stable. PMID:21943042

The Importance of a Gatekeeper Residue on the Aggregation of Transthyretin

PubMed Central

Sant'Anna, Ricardo; Braga, Carolina; Varejão, Nathalia; Pimenta, Karinne M.; Graña-Montes, Ricardo; Alves, Aline; Cortines, Juliana; Cordeiro, Yraima; Ventura, Salvador; Foguel, Debora

2014-01-01

Protein aggregation into β-sheet-enriched amyloid fibrils is associated with an increasing number of human disorders. The adoption of such amyloid conformations seems to constitute a generic property of polypeptide chains. Therefore, during evolution, proteins have adopted negative design strategies to diminish their intrinsic propensity to aggregate, including enrichment of gatekeeper charged residues at the flanks of hydrophobic aggregation-prone segments. Wild type transthyretin (TTR) is responsible for senile systemic amyloidosis, and more than 100 mutations in the TTR gene are involved in familial amyloid polyneuropathy. The TTR 26–57 segment bears many of these aggressive amyloidogenic mutations as well as the binding site for heparin. We demonstrate here that Lys-35 acts as a gatekeeper residue in TTR, strongly decreasing its amyloidogenic potential. This protective effect is sequence-specific because Lys-48 does not affect TTR aggregation. Lys-35 is part of the TTR basic heparin-binding motif. This glycosaminoglycan blocks the protective effect of Lys-35, probably by neutralization of its side chain positive charge. A K35L mutation emulates this effect and results in the rapid self-assembly of the TTR 26–57 region into amyloid fibrils. This mutation does not affect the tetrameric protein stability, but it strongly increases its aggregation propensity. Overall, we illustrate how TTR is yet another amyloidogenic protein exploiting negative design to prevent its massive aggregation, and we show how blockage of conserved protective features by endogenous factors or mutations might result in increased disease susceptibility. PMID:25086037

The role of synaptotagmin I C2A calcium-binding domain in synaptic vesicle clustering during synapse formation

PubMed Central

Gardzinski, Peter; Lee, David W K; Fei, Guang-He; Hui, Kwokyin; Huang, Guan J; Sun, Hong-Shuo; Feng, Zhong-Ping

2007-01-01

Synaptic vesicles aggregate at the presynaptic terminal during synapse formation via mechanisms that are poorly understood. Here we have investigated the role of the putative calcium sensor synaptotagmin I in vesicle aggregation during the formation of soma–soma synapses between identified partner cells using a simple in vitro synapse model in the mollusc Lymnaea stagnalis. Immunocytochemistry, optical imaging and electrophysiological recording techniques were used to monitor synapse formation and vesicle localization. Within 6 h, contact between appropriate synaptic partner cells up-regulated global synaptotagmin I expression, and induced a localized aggregation of synaptotagmin I at the contact site. Cell contacts between non-synaptic partner cells did not affect synaptotagmin I expression. Application of an human immunodeficiency virus type-1 transactivator (HIV-1 TAT)-tagged peptide corresponding to loop 3 of the synaptotagmin I C2A domain prevented synaptic vesicle aggregation and synapse formation. By contrast, a TAT-tagged peptide containing the calcium-binding motif of the C2B domain did not affect synaptic vesicle aggregation or synapse formation. Calcium imaging with Fura-2 demonstrated that TAT–C2 peptides did not alter either basal or evoked intracellular calcium levels. These results demonstrate that contact with an appropriate target cell is necessary to initiate synaptic vesicle aggregation during nascent synapse formation and that the initial aggregation of synaptic vesicles is dependent on loop 3 of the C2A domain of synaptotagmin I. PMID:17317745

Mitochondrial enzymes are protected from stress-induced aggregation by mitochondrial chaperones and the Pim1/LON protease

PubMed Central

Bender, Tom; Lewrenz, Ilka; Franken, Sebastian; Baitzel, Catherina; Voos, Wolfgang

2011-01-01

Proteins in a natural environment are constantly challenged by stress conditions, causing their destabilization, unfolding, and, ultimately, aggregation. Protein aggregation has been associated with a wide variety of pathological conditions, especially neurodegenerative disorders, stressing the importance of adequate cellular protein quality control measures to counteract aggregate formation. To secure protein homeostasis, mitochondria contain an elaborate protein quality control system, consisting of chaperones and ATP-dependent proteases. To determine the effects of protein aggregation on the functional integrity of mitochondria, we set out to identify aggregation-prone endogenous mitochondrial proteins. We could show that major metabolic pathways in mitochondria were affected by the aggregation of key enzyme components, which were largely inactivated after heat stress. Furthermore, treatment with elevated levels of reactive oxygen species strongly influenced the aggregation behavior, in particular in combination with elevated temperatures. Using specific chaperone mutant strains, we showed a protective effect of the mitochondrial Hsp70 and Hsp60 chaperone systems. Moreover, accumulation of aggregated polypeptides was strongly decreased by the AAA-protease Pim1/LON. We therefore propose that the proteolytic breakdown of aggregation-prone polypeptides represents a major protective strategy to prevent the in vivo formation of aggregates in mitochondria. PMID:21209324

Plants adapted to nutrient limitation allocate less biomass into stems in an arid-hot grassland.

PubMed

Yan, Bangguo; Ji, Zhonghua; Fan, Bo; Wang, Xuemei; He, Guangxiong; Shi, Liangtao; Liu, Gangcai

2016-09-01

Biomass allocation can exert a great influence on plant resource acquisition and nutrient use. However, the role of biomass allocation strategies in shaping plant community composition under nutrient limitations remains poorly addressed. We hypothesized that species-specific allocation strategies can affect plant adaptation to nutrient limitations, resulting in species turnover and changes in community-level biomass allocations across nutrient gradients. In this study, we measured species abundance and the concentrations of nitrogen and phosphorus in leaves and soil nutrients in an arid-hot grassland. We quantified species-specific allocation parameters for stems vs leaves based on allometric scaling relationships. Species-specific stem vs leaf allocation parameters were weighted with species abundances to calculate the community-weighted means driven by species turnover. We found that the community-weighted means of biomass allocation parameters were significantly related to the soil nutrient gradient as well as to leaf stoichiometry, indicating that species-specific allocation strategies can affect plant adaptation to nutrient limitations in the studied grassland. Species that allocate less to stems than leaves tend to dominate nutrient-limited environments. The results support the hypothesis that species-specific allocations affect plant adaptation to nutrient limitations. The allocation trade-off between stems and leaves has the potential to greatly affect plant distribution across nutrient gradients. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Role of prion protein aggregation in neurotoxicity.

PubMed

Corsaro, Alessandro; Thellung, Stefano; Villa, Valentina; Nizzari, Mario; Florio, Tullio

2012-01-01

In several neurodegenerative diseases, such as Parkinson, Alzheimer's, Huntington, and prion diseases, the deposition of aggregated misfolded proteins is believed to be responsible for the neurotoxicity that characterizes these diseases. Prion protein (PrP), the protein responsible of prion diseases, has been deeply studied for the peculiar feature of its misfolded oligomers that are able to propagate within affected brains, inducing the conversion of the natively folded PrP into the pathological conformation. In this review, we summarize the available experimental evidence concerning the relationship between aggregation status of misfolded PrP and neuronal death in the course of prion diseases. In particular, we describe the main findings resulting from the use of different synthetic (mainly PrP106-126) and recombinant PrP-derived peptides, as far as mechanisms of aggregation and amyloid formation, and how these different spatial conformations can affect neuronal death. In particular, most data support the involvement of non-fibrillar oligomers rather than actual amyloid fibers as the determinant of neuronal death.

Role of Prion Protein Aggregation in Neurotoxicity

PubMed Central

Corsaro, Alessandro; Thellung, Stefano; Villa, Valentina; Nizzari, Mario; Florio, Tullio

2012-01-01

In several neurodegenerative diseases, such as Parkinson, Alzheimer’s, Huntington, and prion diseases, the deposition of aggregated misfolded proteins is believed to be responsible for the neurotoxicity that characterizes these diseases. Prion protein (PrP), the protein responsible of prion diseases, has been deeply studied for the peculiar feature of its misfolded oligomers that are able to propagate within affected brains, inducing the conversion of the natively folded PrP into the pathological conformation. In this review, we summarize the available experimental evidence concerning the relationship between aggregation status of misfolded PrP and neuronal death in the course of prion diseases. In particular, we describe the main findings resulting from the use of different synthetic (mainly PrP106-126) and recombinant PrP-derived peptides, as far as mechanisms of aggregation and amyloid formation, and how these different spatial conformations can affect neuronal death. In particular, most data support the involvement of non-fibrillar oligomers rather than actual amyloid fibers as the determinant of neuronal death. PMID:22942726

Familial aggregation of age-related macular degeneration in the Utah population.

PubMed

Luo, Ling; Harmon, Jennifer; Yang, Xian; Chen, Haoyu; Patel, Shrena; Mineau, Geraldine; Yang, Zhenglin; Constantine, Ryan; Buehler, Jeanette; Kaminoh, Yuuki; Ma, Xiang; Wong, Tien Y; Zhang, Maonian; Zhang, Kang

2008-02-01

We examined familial aggregation and risk of age-related macular degeneration in the Utah population using a population-based case-control study. Over one million unique patient records were searched within the University of Utah Health Sciences Center and the Utah Population Database (UPDB), identifying 4764 patients with AMD. Specialized kinship analysis software was used to test for familial aggregation of disease, estimate the magnitude of familial risks, and identify families at high risk for disease. The population-attributable risk (PAR) for AMD was calculated to be 0.34. Recurrence risks in relatives indicate increased relative risks in siblings (2.95), first cousins (1.29), second cousins (1.13), and parents (5.66) of affected cases. There were 16 extended large families with AMD identified for potential use in genetic studies. Each family had five or more living affected members. The familial aggregation of AMD shown in this study exemplifies the merit of the UPDB and supports recent research demonstrating significant genetic contribution to disease development and progression.

Pulsed electric field (PEF)-induced aggregation between lysozyme, ovalbumin and ovotransferrin in multi-protein system.

PubMed

Wu, Li; Zhao, Wei; Yang, Ruijin; Yan, Wenxu

2015-05-15

The aggregation of multi-proteins is of great interest in food processing and a good understanding of the formation of aggregates during PEF processing is needed for the application of the process to pasteurize protein-based foods. The aggregates formation of a multi-protein system (containing ovalbumin, ovotransferrin and lysozyme) was studied through turbidity, size exclusion chromatography and SDS-PAGE patterns for interaction studies and binding forces. Results from size exclusion chromatography indicated that there was no soluble aggregates formed during PEF processing. The existence of lysozyme was important to form insoluble aggregates in the chosen ovalbumin solution. The results of SDS-PAGE patterns indicated that lysozyme was prone to precipitate, and was relatively the higher component of aggregates. Citric acid could be effective in inhibiting lysozyme from interacting with other proteins during PEF processing. Blocking the free sulphydryl by N-ethylmaleimide (NEM) did not affect aggregation inhibition. Copyright © 2014 Elsevier Ltd. All rights reserved.

Release and transport of mobile organic matter and biocolloids: A combined physicochemical and microbiological study

NASA Astrophysics Data System (ADS)

Reichel, Katharina; Schaefer, Sabine; Babin, Doreen; Smalla, Konny; Totsche, Kai Uwe

2016-04-01

Biogeochemical interfaces within the aggregate system of soils are "hot spots" of microbial activity and turnover of organic matter. We explore turnover, release and transport of mobile organic matter (MOM), micro-organisms (bio-colloids) and organo-mineral associations using a novel experimental approach employing two-layer columns experiment with matured soil under unsaturated flow conditions. The top layer was spiked with phenanthrene as a tracer for studying the decomposer communities involved in the decomposition of aromatic compounds that derive from lignin in natural systems. Columns were irrigated with artificial rain water with several flow interrupts of different durations. Physicochemical and chemical parameters as well as the microbial community composition were analysed in effluent samples and in soil slices. Release of MOM from the columns was in general controlled by non-equilibrium. Export of total and dissolved organic matter differed significantly in response to the flow interrupts. Effluent comprised organic and organo-mineral components as well as vital competent cells. By molecular biological methods we were even able to show that bacterial consortia exported are rather divers. Depth distribution of the bacterial communities associated with the immobile solid phase indicated high similarities in bacterial communities of the different depth layers and treatments. According to phenanthrene high affinity to the immobile phases, only a small fraction was subject to downstream transport with a strong decrease of the amount residing at the solid phase Our experiments directly prove that intact and competent microorganisms and even communities can be transported under unsaturated flow conditions. Moreover, we found that the dominant carbon source will impact not only the activity of specific microbial taxa but also their mobilization and transport. While total contribution of microbial organism to the mobile organic matter pool seems to be small, the fact that microbes will be mobilized and passively transported to downstream compartments helps to understand the processes that result in the inhabitation of pristine surfaces, thereby resulting in the establishment biogeochemical interfaces and initiation of aggregation in downstream compartments in the vadose zone.

Exploring correlates of turnover among nursing assistants in the National Nursing Home Survey.

PubMed

Temple, April; Dobbs, Debra; Andel, Ross

2011-01-01

High turnover of nursing assistants (NAs) has implications for the quality of nursing home care. Greater understanding of correlates of NA turnover is needed to provide insight into possible retention strategies. This study examined nursing home organizational characteristics and specific job characteristics of staff in relation to turnover of NAs. Cross-sectional data on 944 nationally representative nursing homes were derived from the 2004 National Nursing Home Survey. Using a 3-month turnover rate, 25% of the facilities with the lowest turnover rates were classified as low turnover, 25% of the facilities with the highest turnover were classified as high turnover, and the remaining 50% of the facilities were classified as moderate turnover. Multinomial logistic regression was used to examine organizational and job characteristics associated with low and high turnover compared with moderate turnover. One organizational characteristic, staffing levels at or greater than 4.0 hours per patient day, was associated with greater odds of low NA turnover and reduced odds of high NA turnover. Job characteristics including higher wages and union membership were associated with greater odds of low NA turnover, whereas wages, fully paid health insurance, employee assistance benefits, and involvement in resident care planning were associated with reduced odds of high NA turnover. The results of this study suggest that job characteristics of NA staff may be particularly important for turnover. Specifically, the provision of competitive wages and benefits (particularly health insurance) and involvement of NAs in resident care planning could potentially reduce NA turnover, as could maintaining high levels of nurse staffing.

Exploring correlates of turnover among nursing assistants in the National Nursing Home Survey.

PubMed

Temple, April; Dobbs, Debra; Andel, Ross

2009-01-01

High turnover of nursing assistants (NAs) has implications for the quality of nursing home care. Greater understanding of correlates of NA turnover is needed to provide insight into possible retention strategies. This study examined nursing home organizational characteristics and specific job characteristics of staff in relation to turnover of NAs. Cross-sectional data on 944 nationally representative nursing homes were derived from the 2004 National Nursing Home Survey. Using a 3-month turnover rate, 25% of the facilities with the lowest turnover rates were classified as low turnover, 25% of the facilities with the highest turnover were classified as high turnover, and the remaining 50% of the facilities were classified as moderate turnover. Multinomial logistic regression was used to examine organizational and job characteristics associated with low and high turnover compared with moderate turnover. One organizational characteristic, staffing levels at or greater than 4.0 hours per patient day, was associated with greater odds of low NA turnover and reduced odds of high NA turnover. Job characteristics including higher wages and union membership were associated with greater odds of low NA turnover, whereas wages, fully paid health insurance, employee assistance benefits, and involvement in resident care planning were associated with reduced odds of high NA turnover. The results of this study suggest that job characteristics of NA staff may be particularly important for turnover. Specifically, the provision of competitive wages and benefits (particularly health insurance) and involvement of NAs in resident care planning could potentially reduce NA turnover, as could maintaining high levels of nurse staffing.

RETREG1 (FAM134B): A new player in human diseases: 15 years after the discovery in cancer.

PubMed

Islam, Farhadul; Gopalan, Vinod; Lam, Alfred King-Yin

2018-06-01

FAM134B (family with sequence similarity 134, member B)/RETREG1 and its functional roles are relatively new in human diseases. This review aimed to summarize various functions of FAM134B since our first discovery of the gene in 2001. The protein encoded by FAM134B is a reticulophagy receptor that regulates turnover of the endoplasmic reticulum (ER) by selective phagocytosis. Absence or non-functional expression of FAM134B protein impairs ER-turnover and thereby is involved in the pathogenesis of some human diseases. FAM134B inhibition contributes to impair proteostasis in the ER due to the accumulation of misfolded or aggregated proteins, which in turn leads to compromised neuronal survival and progressive neuronal degenerative diseases. Mutations in FAM134B associated with hereditary sensory and autonomic neuropathy type IIB (HSAN IIB). Selective cleavage of FAM134B by Dengue, Zika, and West Nile virus encoded protease NS2B3 leads to the increased production of infection units, whereas upregulation of FAM134B inhibits viral replication. In cancer, FAM134B acts as a tumor suppressor and inhibit cancer growth both in-vitro and in-vivo. Pharmacological upregulation of FAM134B resulted in reduced cancer cell growth and proliferation. In addition, FAM134B mutations are common in patients with colorectal adenocarcinoma, and oesophageal squamous cell carcinoma. These mutations and expression changes of FAM134B were associated with the biological aggressiveness of these cancers. FAM134B also plays a role in allergic rhinitis, vascular dementia, and identification of stem cells. Taken together, information available in the literature suggests that FAM134B plays critical roles in human diseases, by interacting with different biological and chemical mediators, which are primarily regulated by ER turnover. © 2017 Wiley Periodicals, Inc.

UV Irradiation and Humic Acid Mediate Aggregation of Aqueous Fullerene (nC60) Nanoparticles

EPA Science Inventory

The transport and fate of engineered nanomaterials is affected by multiple environmental factors, including sunlight and natural organic matter. In this study, the initial aggregation kinetics of aqueous fullerene (nC60) nanoparticles before and after UVA irradiation was investig...

Aggregate Unemployment Decreases Individual Returns to Education

ERIC Educational Resources Information Center

Ammermueller, Andreas; Kuckulenz, Anja; Zwick, Thomas

2009-01-01

Aggregate unemployment may affect individual returns to education through qualification-specific responses in participation and wage bargaining. This paper shows that an increase in regional unemployment by 1% decreases returns to education by 0.005 percentage points. This implies that higher skilled employees are better sheltered from labour…

A cell-based assay for aggregation inhibitors as therapeutics of polyglutamine-repeat disease and validation in Drosophila

NASA Astrophysics Data System (ADS)

Apostol, Barbara L.; Kazantsev, Alexsey; Raffioni, Simona; Illes, Katalin; Pallos, Judit; Bodai, Laszlo; Slepko, Natalia; Bear, James E.; Gertler, Frank B.; Hersch, Steven; Housman, David E.; Marsh, J. Lawrence; Michels Thompson, Leslie

2003-05-01

The formation of polyglutamine-containing aggregates and inclusions are hallmarks of pathogenesis in Huntington's disease that can be recapitulated in model systems. Although the contribution of inclusions to pathogenesis is unclear, cell-based assays can be used to screen for chemical compounds that affect aggregation and may provide therapeutic benefit. We have developed inducible PC12 cell-culture models to screen for loss of visible aggregates. To test the validity of this approach, compounds that inhibit aggregation in the PC12 cell-based screen were tested in a Drosophila model of polyglutamine-repeat disease. The disruption of aggregation in PC12 cells strongly correlates with suppression of neuronal degeneration in Drosophila. Thus, the engineered PC12 cells coupled with the Drosophila model provide a rapid and effective method to screen and validate compounds.

Estimating and preventing hospital internal turnover of newly licensed nurses: A panel survey.

PubMed

Kovner, Christine T; Djukic, Maja; Fatehi, Faridaben K; Fletcher, Jason; Jun, Jin; Brewer, Carol; Chacko, Thomas

2016-08-01

Registered nurse job turnover is an ongoing problem in the USA resulting in significant financial costs to both organizations and society. Most research has focused on organizational turnover with few studies about internal or unit-level turnover. Turnover of new nurses in hospitals has particular importance as almost 80% of new nurses work in hospitals and have higher turnover rates when compared to experienced nurses. This paper focuses on new nurses' unit-level turnover rates in hospitals. The purpose of this study is to: (1) identify factors that predict new nurses staying in the same units, positions, and job titles to inform unit-level retention strategies, and (2) examine the changes in work environment perceptions over time between nurses who remain in the same unit, position, and title to those who changed unit, position and/or title. A panel survey design was used to analyze changes over time. Participants were newly licensed registered nurses who were licensed for the first time between August 1st, 2004 and July 31st, 2005. The nurses came from metropolitan statistical areas or rural areas that were nested to reflect a nationally representative USA sample (58% response rate). The analytic sample for this study was 1335. Data were collected in January 2006 and 2007 following the Dillman total design approach. All potential respondents received paper surveys and non-responders received repeated mailings. Using multinomial regression the five variables with the largest effects on unit retention were (1) variety (positive), (2) having another job for pay (negative), (3) first basic degree (having a bachelors or higher degree increased the probability of staying), (4) negative affectivity (positive), and (5) job satisfaction (positive). Nurses who changed unit, and/or position, and/or title reported more positive change scores on a variety of work attitudes. Almost 30% of new nurses working in hospitals leave their unit, and/or position, and/or title during their first year of work. Our results point to the variables on which managers can focus to improve unit-level retention of new nurses. Although participants were from a nationally representative sample of nurses who were newly licensed in 2004-2005, with the geographical shifts in the USA population in the last 10 years the sample may not be geographically representative of new nurses who graduated in 2015. Copyright © 2016. Published by Elsevier Ltd.

Turn-over rate of academic faculty at the College of Health Sciences, Addis Ababa University: a 20-year analysis (1991 to 2011).

PubMed

Hailu, Alemayehu; Mariam, Damen Haile; Fekade, Daniel; Derbew, Miliard; Mekasha, Amha

2013-12-01

Faculty turn-over affects both workers and organizations. Turnover of faculty and researchers is increasing alarmingly and costing the universities and the country at large. Fast turnover of health professionals from the health system and from academic institutions has recently received substantial attention from both academia and health sector managers. This paper calculates the faculty turnover rate at the College of Health Sciences of Addis Ababa University during the period of September 1991 to August 2011. The study was conducted at the College of Health Sciences, Addis Ababa University. Retrospective analysis of employee records was done. All records of the faculty that were working in the College during the 20-year period, starting from September 1991 to August 2011 were retrospectively reviewed. Data were collected from the employee records accessed from the College's human resources database and supplemented by payroll sheets and different reports. A structured checklist was used to extract the required data from the database. The crude turnover rate for academic faculty was calculated. Within the 20-year period of September 1991 to August 2011, a total of 120 faculty members left. The overall turn-over rate was 92.8 %. The rate in the most recent five years (172 %) is 8.5 times higher than the rate for the first five years (20 %). The average retention period before the termination of an employment contract was 4.9 years. The top five departments where employment contracts were relatively higher include: Nursing 15 (15.6 %), Internal Medicine 12 (12.5%), Public Health 10 (10.4%), Pediatrics 9 (9.4%) and Surgery 9 (9.4%). About two thirds (66.6%) of the faculty who were leaving were at the ranks of assistant professorship and above. This study revealed that outflow of faculty has been continuously increasing in the period reviewed. This implies that the College had been losing highly skilled professionals with considerably higher costs in monetary terms. In this regard, an urgent response is required to retain or significantly decrease the outflow of faculty. Different motivation and retention mechanisms should be identified and implemented. Various modalities of faculty development programs should also be initiated.

Sound absorption and morphology characteristic of porous concrete paving blocks

NASA Astrophysics Data System (ADS)

Halim, N. H. Abd; Nor, H. Md; Ramadhansyah, P. J.; Mohamed, A.; Hassan, N. Abdul; Ibrahim, M. H. Wan; Ramli, N. I.; Nazri, F. Mohamed

2017-11-01

In this study, sound absorption and morphology characteristic of Porous Concrete Paving Blocks (PCPB) at different sizes of coarse aggregate were presented. Three different sizes of coarse aggregate were used; passing 10 mm retained 5 mm (as Control), passing 8 mm retained 5 mm (8 - 5) and passing 10 mm retained 8 mm (10 - 8). The sound absorption test was conducted through the impedance tube at different frequency. It was found that the size of coarse aggregate affects the level of absorption of the specimens. It also shows that PCPB 10 - 8 resulted in high sound absorption compared to the other blocks. On the other hand, microstructure morphology of PCPB shows a clearer version of existing micro-cracks and voids inside the specimens which affecting the results of sound absorption.

Turnover among healthcare professionals.

PubMed

Wood, Ben D

2009-01-01

Turnover among healthcare professionals is a costly consequence. The existing body of knowledge on healthcare professional turnover is correlated with job satisfaction levels. A landmark study differentiated 2 areas of job satisfaction categories: satisfiers and dissatisfiers (intrinsic and extrinsic motivators). The aim of this article is to examine existing research on precursors of turnover, such as burnout behaviors experienced by healthcare professionals, job satisfaction levels, employee organizational commitment, health complications which precede turnover, some current strategies to reduce turnover, and some effects CEO turnover has on employee turnover intentions.

Effects of Combined Application of Biogas Slurry and Chemical Fertilizer on Soil Aggregation and C/N Distribution in an Ultisol.

PubMed

Zheng, Xuebo; Fan, Jianbo; Xu, Lei; Zhou, Jing

2017-01-01

Unreasonable use of chemical fertilizer (CF) on agricultural soil leads to massive losses of soil organic carbon (SOC) and total nitrogen (TN) in tropical and subtropical areas, where soil conditions are unfavorable for aggregate formation. This study evaluated the effects of combined application of biogas slurry (BS) plus CF on soil aggregation and aggregate-associated C/N concentration and storage in an Ultisol. Six treatments included: no fertilizer (T1), CF only (T2), partial (15% (T3), 30% (T4) and 45% (T5)) substitution of TN with BS and BS only (T6). Soil mechanical-stable aggregates (MSAs) formation and stability as well as MSAs-associated C/N concentration and storage were observed in different aggregate sizes (>5, 5-2, 2-1, 1.0-0.5, 0.50-0.25 and <0.25 mm). The proportion of MSAs >5 mm significantly increased with BS substitution (T5), while the proportions of MSAs 1.0-0.5 mm, MSAs 0.50-0.25 mm and MSAs <0.25 mm significantly decreased. Both mean weight diameter and geometric mean diameter were highest in T5, which improved soil aggregation stability as well as resulted in significantly higher SOC and TN concentrations and storage in MSAs >0.5 mm that constituted 72-82% of MSAs. Stepwise regression analysis showed that MSAs >5 mm, SOC in MSAs >5 mm and TN in MSAs >5 mm were the dominant variables affecting aggregate stability. Meanwhile SOC in MSAs <0.25 mm and TN in MSAs 2-1 mm were independent variables affecting SOC and TN concentrations in bulk soils. Therefore, certain rate of combined application of BS plus CF is an effective, eco-friendly way to improve soil quality in an Ultisol.

Aggregate Stability and Erodibility of Purple Soil on Sloping Farmland as affected by different Soil Thickness

NASA Astrophysics Data System (ADS)

Huang, Xinjun; Zhang, Qingwen; Chen, Shanghong; Dong, Yuequn; Xiao, Meijia; Hamed, Lamy Mamdoh Mohamed

2017-04-01

Soil thickness is basic limiting condition for purple soil, not only due to its effect on crop production, but also its effect on soil structure. Steady-state of soil thickness will be achieved over time, as result the soil aggregate which the key factor of soil erodibility can be enhanced as well. However, the effect of soil thickness on aggregates stability and the characteristics of soil erodibility in sloping land have not yet fully understood.A field survey was conducted in hilly area of Sichuan region located in southeast China to study the relationship between soil aggregate stability and soil erodibility on sloping farmland under different four thickness (100cm, 80cm, 60cm, 30cm) of purple soil. Based on two different sieving methods (Dry and Wet sieving), we analyzed soil aggregate stability and its effect on soil erodibility within depth of 0-30cm soil layers. The results indicated that: Water stable aggregate on sloping farmland was ranged between 37.9% to 58.6%, where it increased with increasing the soil thickness. Moreover, fractal dimension calculated from dry-sieving and wet-sieving was 2.06-2.49 and 2.70-2.85 respectively, where it decreased with decreasing the soil thickness. The overall soil erodibility was 0.05-1.00 and a negative significant correlation was found between soil aggregate stability and erodibility(P<0.01). Moreover, farmland with thick soil profile tended to be high in soil erodibility within the top soil layer (0-30cm). The results reveal that soil thickness can affect soil aggregate stability as well as erodibility. As soil thickness increased, the top soil became more stable and less erodible. Keywords：purple soil; soil thickness; soil aggregate；soil erodibility

Increases in soil aggregation following phosphorus additions in a tropical premontane forest are not driven by root and arbuscular mycorrhizal fungal abundances

NASA Astrophysics Data System (ADS)

Camenzind, Tessa; Papathanasiou, Helena; Foerster, Antje; Dietrich, Karla; Hertel, Dietrich; Homeier, Juergen; Oelmann, Yvonne; Olsson, Pål Axel; Suárez, Juan; Rillig, Matthias

2015-12-01

Tropical ecosystems have an important role in global change scenarios, in part because they serve as a large terrestrial carbon pool. Carbon protection is mediated by soil aggregation processes, whereby biotic and abiotic factors influence the formation and stability of aggregates. Nutrient additions may affect soil structure indirectly by simultaneous shifts in biotic factors, mainly roots and fungal hyphae, but also via impacts on abiotic soil properties. Here, we tested the hypothesis that soil aggregation will be affected by nutrient additions primarily via changes in arbuscular mycorrhizal fungal (AMF) hyphae and root length in a pristine tropical forest system. Therefore, the percentage of water-stable macroaggregates (> 250µm) (WSA) and the soil mean weight diameter (MWD) was analyzed, as well as nutrient contents, pH, root length and AMF abundance. Phosphorus additions significantly increased the amount of WSA, which was consistent across two different sampling times. Despite a positive effect of phosphorus additions on extraradical AMF biomass, no relationship between WSA and extra-radical AMF nor roots was revealed by regression analyses, contrary to the proposed hypothesis. These findings emphasize the importance of analyzing soil structure in understudied tropical systems, since it might be affected by increasing nutrient deposition expected in the future.

Dabigatran and rivaroxaban do not affect AA- and ADP-induced platelet aggregation in patients receiving concomitant platelet inhibitors.

PubMed

Olivier, Christoph B; Weik, Patrick; Meyer, Melanie; Weber, Susanne; Diehl, Philipp; Bode, Christoph; Moser, Martin; Zhou, Qian

2016-08-01

Dabigatran and rivaroxaban are novel, vitamin K-independent oral anticoagulants (NOACs) and act via antagonism of the coagulation factor (F) IIa (dabigatran) or FXa (rivaroxaban), respectively. Compared to vitamin-K-antagonists, NOACs have shown non-inferiority of risk and benefit in patients with non valvular atrial fibrillation (AF). In clinical practice there is increasing use of NOACs combined with platelet inhibitors in patients with AF and coronary artery disease. However, whether NOACs affect the function of platelet inhibitors remains incompletely known. This observational study aimed to assess the platelet function in patients receiving dabigatran or rivaroxaban and concomitant platelet inhibitors. A single centre observational study was performed analysing the platelet aggregation of patients treated with dabigatran or rivaroxaban with or without concomitant platelet inhibitors. Measurements before the initiation of NOAC therapy served as the respective control group. Platelet aggregation was measured by multiple electrode aggregometry and was induced with adenosine diphosphate (ADP, 6.5 µM) and arachidonic acid (AA, 0.5 mM), respectively. In order to evaluate whether NOACs interact with platelet inhibition by ASA or the P2Y12-antagonist clopidogrel, 87 patients were grouped according to their concomitant antiplatelet medication. Comparing the ADP- and AA-induced platelet aggregation in patients without concomitant platelet inhibitors (n = 45) no significant differences under therapy with dabigatran (d) or rivaroxaban (r) compared to the control group (c) were observed. In patients taking clopidogrel as a concomitant platelet inhibitor (n = 21), neither dabigatran nor rivaroxaban affected the ADP-induced platelet aggregation (c 20 ± 11, d 21 ± 14, r 18 ± 8 AU*min, p = 0.200). Patients receiving dabigatran or rivaroxaban in combination with ASA (n = 42; 21 ASA only, 21 ASA + clopidogrel) showed no significant differences of the AA-induced aggregation compared to the control group (c 10 ± 8, d 9 ± 7, r 10 ± 8 AU*min, p = 0.810). The antiplatelet effects of ASA and clopidogrel monitored by AA- or ADP-induced platelet aggregation were not affected by NOAC therapy.

Hypercortisolism as a Potential Concern for Submariners

DTIC Science & Technology

2010-12-01

adverse physiological and psychological states such as glucose intolerance, dyslipidemia , obesity, hypertension (all components of metabolic syndrome...induce hyperglycemia, dyslipidemia , increased amino acid turnover, acidosis, loss of lean body mass, alterations in expression of metabolic genes...glucose intolerance, dyslipidemia , and stress-mediated hypertension are positively affected by regular exercise (93). The obvious benefits that regular

Succession Planning and Management: A Guide to Organizational Systems and Practices

ERIC Educational Resources Information Center

Berke, David

2005-01-01

The purpose of succession-related practices is to ensure that there are ready replacements for key positions in an organization so that turnover will not negatively affect the organization's performance. CCL first published an annotated bibliography on succession planning in 1995. That bibliography focused primarily on the link between succession…

Linking the Occupational Pressures of College Presidents to Presidential Turnover

ERIC Educational Resources Information Center

Tekniepe, Robert J.

2014-01-01

Community colleges are expected to serve the needs of their local communities. Hence, college presidents are called on to lead this collaboration between the college and the community. Presidents, however, are affected by a multitude of factors that contribute to abridged tenures, a scenario that can have harmful effects on the educational…

Linking Work-Family Issues to the Bottom Line. Report Number 962.

ERIC Educational Resources Information Center

Friedman, Dana E.

A 1988 symposium on the effect of family problems on the corporate bottom line and a review of more than 80 other studies have confirmed that business investments in programs and policies to resolve family-work conflicts yield returns. Family issues/problems have been documented to affect employee recruitment, productivity, turnover, and…

Calcium homeostasis and bone metabolic responses to high-protein diets during energy deficit in healthy young adults: a randomized control trial

USDA-ARS?s Scientific Manuscript database

Although consuming dietary protein above current recommendations during energy deficit enhances blood lipid profiles and preserves lean body mass, concerns have been raised regarding effects of high-protein diets on bone health. To determine whether calcium homeostasis and bone turnover are affected...

Engineer: The Professional Bulletin of Army Engineers. Volume 41, May-August 2011

DTIC Science & Technology

2011-08-01

agement Authority ( NDMA ), more than 20 million Paki- stanis have been affected by this catastrophic event—the country’s worst monsoon season in 80 years... NDMA for the Pakistan mil- itary engineers to install, and an official bridge turnover ceremony was held at the U.S. embassy in Islamabad on 1

Turnover of soil carbon pools following addition of switchgrass-derived biochar to four soils

USDA-ARS?s Scientific Manuscript database

The amendment of soils with biochar may improve plant growth and sequester carbon, especially in marginal soils not suitable for the majority of commodity production. While biochar can persist in soils, it is not clear whether its persistence is affected by soil type. Moreover, we know little of how...

Modifying the Program and Providing for Change. The ACTFL Foreign Language Education Series, Vol. 10.

ERIC Educational Resources Information Center

Loew, Helene Z.

Rapidly changing social, economic, and political conditions, declining enrollments, fiscal restraints, and decline in teacher turnover are factors that affect curriculum development. Staff development may be considered the most important instrument available for providing educational personnel with the skills and knowledge necessary to adjust to…

Teacher Perceptions of Professional Learning Communities Related to Teacher Retention

ERIC Educational Resources Information Center

Troutt, Amy

2014-01-01

Teacher retention continues to be of concern for schools across the United States. High teacher turnover results in a loss of teacher quality, loss of commitment, and a loss of funding to school districts. Research suggests that increased teacher retention is affected by induction, mentoring/coaching, engaging in action research, professional…

Determination of bile acid pool size, turnover time, and distribution of male broiler chicks during the first 6 weeks posthatch using SEHCAT, a gamma ray-emitting bile acid analogue.

PubMed

Green, J; Kellogg, T; Keirs, R; Cooper, R

1987-11-01

A bile acid analogue, SEHCAT (tauro-23-75SE-selena-homocholic acid), was used to determine bile acid pool size, turnover time, and distribution in the developing broiler chick. Bile acid pool size was significantly affected by age and followed a quintic trend (a fifth degree polynomial). It remained steady until 30 days of age when it decreased significantly and then rose significantly at 37 days of age. The bile acid pool half-life remained constant until 28 days of age when it increased significantly and then held steady until it increased again at 8 wk of age following a quartic trend. The distribution of bile acids was affected by age with the amount in the gizzard, duodenum, cloaca, liver, and gall bladder varying significantly with age. Jejunal, ileal, and cecal bile acids did not vary significantly with age. Liver bile acid levels followed a quintic trend, rising until 23 days of age and dropping sharply at 30 days of age and holding steady.

Effects of disturbance on contribution of energy sources to growth of juvenile chinook salmon (Oncorhynchus tshawytscha) in boreal streams

USGS Publications Warehouse

Perry, R.W.; Bradford, M.J.; Grout, J.A.

2003-01-01

We used stable isotopes of carbon in a growth-dependent tissue-turnover model to quantify the relative contribution of autochthonous and terrestrial energy sources to juvenile chinook salmon (Oncorhynchus tshawytscha) in five small boreal streams tributary to the upper Yukon River. We used a tissue-turnover model because fish did not grow enough to come into isotopic equilibrium with their diet. In two streams, autochthonous energy sources contributed 23 and 41% to the growth of juvenile salmon. In the other three, fish growth was largely due to terrestrial (i.e., allochthonous) energy sources. This low contribution of autochthonous energy appeared to be related to stream-specific disturbances: a recent forest fire impacted two of the streams and the third was affected by a large midsummer spate during the study. These disturbances reduced the relative abundance of herbivorous macroinvertebrates, the contribution of autochthonous material to other invertebrates, and ultimately, the energy flow between stream algae and fish. Our findings suggest that disturbances to streams can be an important mechanism affecting transfer of primary energy sources to higher trophic levels.

The effects of sex, tissue type, and dietary components on stable isotope discrimination factors (Δ13C and Δ15N) in mammalian omnivores.

PubMed

Kurle, Carolyn M; Koch, Paul L; Tershy, Bernie R; Croll, Donald A

2014-01-01

We tested the effects of sex, tissue, and diet on stable isotope discrimination factors (Δ(13)C and Δ(15)N) for six tissues from rats fed four diets with varied C and N sources, but comparable protein quality and quantity. The Δ(13)C and Δ(15)N values ranged from 1.7-4.1‰ and 0.4-4.3‰, respectively. Females had higher Δ(15)N values than males because males grew larger, whereas Δ(13)C values did not differ between sexes. Differences in Δ(13)C values among tissue types increased with increasing variability in dietary carbon sources. The Δ(15)N values increased with increasing dietary δ(15)N values for all tissues except liver and serum, which have fast stable isotope turnover times, and differences in Δ(15)N values among tissue types decreased with increasing dietary animal protein. Our results demonstrate that variability in dietary sources can affect Δ(13)C values, protein source affects Δ(15)N values even when protein quality and quantity are controlled, and the isotope turnover rate of a tissue can influence the degree to which diet affects Δ(15)N values.

Addressing employee turnover and retention: keeping your valued performers.

PubMed

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.

Reconstructing Economics in Light of the 2007-? Financial Crisis

ERIC Educational Resources Information Center

Friedman, Benjamin M.

2010-01-01

The lessons learned from the recent financial crisis should significantly reshape the economics profession's thinking, including, importantly, what we teach our students. Five such lessons are that we live in a monetary economy and therefore aggregate demand and policies that affect aggregate demand are determinants of real economic outcomes; that…

Lumpy Demand and the Diagrammatics of Aggregation.

ERIC Educational Resources Information Center

Shmanske, Stephen; Packey, Daniel

1999-01-01

Illustrates how a simple discontinuity in an individual's demand curve, or inverse-demand curve, affects the shape of market aggregate curves. Shows, for private goods, that an infinitesimal change in quantity can lead to large changes in consumption patterns; for collective goods, the analysis suggests a theory of coalition building. (DSK)

Workplace violence in nursing today.

PubMed

Araujo, Susan; Sofield, Laura

2011-12-01

Workplace violence is not a new phenomenon and is often sensationalized by the media when an incident occurs. Verbal abuse is a form of workplace violence that leaves no scars. However, for nurses, the emotional damage to the individual can affect productivity, increase medication errors, incur absenteeism, and decrease morale and overall satisfaction within the nursing profession. This results in staffing turnover and creates a hostile work environment that affects the culture within the organization. Copyright © 2011 Elsevier Inc. All rights reserved.

Personality traits and ego-network dynamics

PubMed Central

Centellegher, Simone; López, Eduardo; Saramäki, Jari; Lepri, Bruno

2017-01-01

Strong and supportive social relationships are fundamental to our well-being. However, there are costs to their maintenance, resulting in a trade-off between quality and quantity, a typical strategy being to put a lot of effort on a few high-intensity relationships while maintaining larger numbers of less close relationships. It has also been shown that there are persistent individual differences in this pattern; some individuals allocate their efforts more uniformly across their networks, while others strongly focus on their closest relationships. Furthermore, some individuals maintain more stable networks than others. Here, we focus on how personality traits of individuals affect this picture, using mobile phone calls records and survey data from the Mobile Territorial Lab (MTL) study. In particular, we look at the relationship between personality traits and the (i) persistence of social signatures, namely the similarity of the social signature shape of an individual measured in different time intervals; (ii) the turnover in egocentric networks, that is, differences in the set of alters present at two consecutive temporal intervals; and (iii) the rank dynamics defined as the variation of alter rankings in egocentric networks in consecutive intervals. We observe that some traits have effects on the stability of the social signatures as well as network turnover and rank dynamics. As an example, individuals who score highly in the Openness to Experience trait tend to have higher levels of network turnover and larger alter rank variations. On broader terms, our study shows that personality traits clearly affect the ways in which individuals maintain their personal networks. PMID:28253333

From job stress to intention to leave among hospital nurses: A structural equation modelling approach.

PubMed

Lo, Wen-Yen; Chien, Li-Yin; Hwang, Fang-Ming; Huang, Nicole; Chiou, Shu-Ti

2018-03-01

The aim of this study was to examine the structural relationships linking job stress to leaving intentions through job satisfaction, depressed mood and stress adaptation among hospital nurses. High turnover among nurses is a global concern. Structural relationships linking job stress to leaving intentions have not been thoroughly examined. Two nationwide cross-sectional surveys of full-time hospital staff in 2011 and 2014. The study participants were 26,945 and 19,386 full-time clinical nurses in 2011 and 2014 respectively. Structural equation modelling was used to examine the interrelationships among the study variables based on the hypothesized model. We used cross-validation procedures to ensure the stability and validity of the model in the two samples. There were five main paths from job stress to intention to leave the hospital. In addition to the direct path, job stress directly affected job satisfaction and depressed mood, which in turn affected intention to leave the hospital. Stress adaptation mitigated the effects of job stress on job satisfaction and depressed mood, which led to intention to leave the hospital. Intention to leave the hospital preceded intention to leave the profession. Those variables explained about 55% of the variance in intention to leave the profession in both years. The model fit was good for both samples, suggesting validity of the model. Strategies to decrease turnover intentions among nurses could focus on creating a less stressful work environment, increasing job satisfaction and stress adaptation and decreasing depressed mood. Hospitals should cooperate in this issue to decrease nurse turnover. © 2017 John Wiley & Sons Ltd.

Modeling habitat dynamics accounting for possible misclassification

USGS Publications Warehouse

Veran, Sophie; Kleiner, Kevin J.; Choquet, Remi; Collazo, Jaime; Nichols, James D.

2012-01-01

Land cover data are widely used in ecology as land cover change is a major component of changes affecting ecological systems. Landscape change estimates are characterized by classification errors. Researchers have used error matrices to adjust estimates of areal extent, but estimation of land cover change is more difficult and more challenging, with error in classification being confused with change. We modeled land cover dynamics for a discrete set of habitat states. The approach accounts for state uncertainty to produce unbiased estimates of habitat transition probabilities using ground information to inform error rates. We consider the case when true and observed habitat states are available for the same geographic unit (pixel) and when true and observed states are obtained at one level of resolution, but transition probabilities estimated at a different level of resolution (aggregations of pixels). Simulation results showed a strong bias when estimating transition probabilities if misclassification was not accounted for. Scaling-up does not necessarily decrease the bias and can even increase it. Analyses of land cover data in the Southeast region of the USA showed that land change patterns appeared distorted if misclassification was not accounted for: rate of habitat turnover was artificially increased and habitat composition appeared more homogeneous. Not properly accounting for land cover misclassification can produce misleading inferences about habitat state and dynamics and also misleading predictions about species distributions based on habitat. Our models that explicitly account for state uncertainty should be useful in obtaining more accurate inferences about change from data that include errors.

Newcomer nurses' organisational socialisation and turnover intention during the first 2 years of employment.

PubMed

Tomietto, Marco; Rappagliosi, Cristina M; Sartori, Riccardo; Battistelli, Adalgisa

2015-10-01

The aim of this study was to determine which organisational socialisation contents affect turnover intention in newcomer nurses within their first 2 years of employment. Strategies to decrease turnover are a priority for improving organisational stability, reducing costs and enhancing effective nursing care. A cross-sectional design was employed, and standardised scales were used. The sample was divided into three groups: 0-6, 7-12 and 13-24 months of employment. Regression analyses were performed. A total of 156 Italian nurses participated in this study. In the 0-6 months group (model 1), the main factors that decreased turnover intention were competence acquisition (β = -0.42, P < 0.01) and comprehension of organisational rules (β = -0.38, P < 0.01). In the 7-12 months group (model 2), workgroup integration was relevant (β = -0.33, P = 0.02) and in the second year (model 3), the main factor was opportunities for professional development (β = -0.30, P = 0.05). Newcomer nurses were sensitive to different organisational socialisation contents over time. This result supports planning different on-boarding strategies to enhance organisational socialisation success and to improve nurse retention. Useful strategies to improve retention include enhancing task mastery and workgroup integration at the ward level and a professional development plan at the organisational level. © 2014 John Wiley & Sons Ltd.

Factors affecting the retention of nurses. A survival analysis.

PubMed

Alonazi, Noufa A; Omar, Maye A

2013-03-01

To identify and explore factors that mostly influence nurses' turnover and retention, and to estimate the length of employment for nurses in the hospital. This is a retrospective cohort study examining the standard Exit Questionnaires completed by all the female pediatric nurses who joined and left the hospital during the period between January 2006 and October 2010. The Developed Questionnaires where completed by nurses who were still employees in October 2010. The nurses who left the job will be considered as events and the nurses who are still working will be considered as censored. The study took place at the Pediatric Department, Prince Sultan Military Medical City (PSMMC), Riyadh, Saudi Arabia. A total of 254 nurses were included in the study. Most of the nurses left their jobs due to family reasons (39.7%) followed by other reasons (37.3%). Seventy five percent of all the pediatric nurses remained in their jobs, on average, for 2.2 years. Both simple and multivariate analysis indicated a strong positive correlation between length of employment (turnover) and the demographic and organization factors. This study has identified several factors that played a key role in staff retention, which can help in predicting nursing turnover at PSMMC. The findings of this study could help PSMMC and its Nursing Administration, in particular, to understand the seriousness of the high turnover rates, to develop and implement strategies to reduce this problem, and improve the retention of nursing staff.

A complete thermodynamic analysis of enzyme turnover links the free energy landscape to enzyme catalysis.

PubMed

Jones, Hannah B L; Wells, Stephen A; Prentice, Erica J; Kwok, Anthony; Liang, Liyin L; Arcus, Vickery L; Pudney, Christopher R

2017-09-01

Our understanding of how enzymes work is coloured by static structure depictions where the enzyme scaffold is presented as either immobile, or in equilibrium between well-defined static conformations. Proteins, however, exhibit a large degree of motion over a broad range of timescales and magnitudes and this is defined thermodynamically by the enzyme free energy landscape (FEL). The role and importance of enzyme motion is extremely contentious. Much of the challenge is in the experimental detection of so called 'conformational sampling' involved in enzyme turnover. Herein we apply combined pressure and temperature kinetics studies to elucidate the full suite of thermodynamic parameters defining an enzyme FEL as it relates to enzyme turnover. We find that the key thermodynamic parameters governing vibrational modes related to enzyme turnover are the isobaric expansivity term and the change in heat capacity for enzyme catalysis. Variation in the enzyme FEL affects these terms. Our analysis is supported by a range of biophysical and computational approaches that specifically capture information on protein vibrational modes and the FEL (all atom flexibility calculations, red edge excitation shift spectroscopy and viscosity studies) that provide independent evidence for our findings. Our data suggest that restricting the enzyme FEL may be a powerful strategy when attempting to rationally engineer enzymes, particularly to alter thermal activity. Moreover, we demonstrate how rational predictions can be made with a rapid computational approach. © 2017 Federation of European Biochemical Societies.

Productivity and turnover in PCPs: the role of staff participation in decision-making.

PubMed

Hung, Dorothy Y; Rundall, Thomas G; Cohen, Deborah J; Tallia, Alfred F; Crabtree, Benjamin F

2006-10-01

Efforts to redesign primary care practices are beginning to address how decisions are made in the practice setting. This study contributes to these efforts by examining associations between staff participation in decision-making, productivity, and turnover in primary care practices. The study is informed by organizational theories of participation that emphasize cognitive and affective influences on employee output and behavior. This research used data collected from primary care practices involved in a national initiative sponsored by the Robert Wood Johnson Foundation. Cross-sectional survey data on organizational structures and attributes among 49 practices were analyzed. Regression analysis was used to examine associations among practice productivity, staff participation in decision-making, and formal structures such as staff meetings. Associations between staff turnover and participative decision-making were also examined. Staff participation in decisions regarding quality improvement, practice change, and clinical operations was positively associated with practice productivity, whereas formal structures such as staff meetings were not. In addition, higher levels of participation in decision-making were associated with reduced turnover among nonclinicians and administrative staff. Examination of organizational features is increasingly recognized as a key to improving primary care performance. Study findings suggest that one important strategy may be implementation of a participative model emphasizing greater staff involvement in practice decisions. This may enhance information-sharing, work satisfaction, and commitment to organizational decisions, all of which can lead to beneficial outcomes such as increased productivity and stability in primary care practices.

Employee Turnover among Full-time Public Librarians.

ERIC Educational Resources Information Center

Rubin, Richard

1989-01-01

A study of employee turnover in 31 public libraries in the American Midwest established baseline turnover rates and examined the relationship of gender to turnover behavior. Findings showed that: turnover rates are low compared to other occupations; and turnover rates of males and females are similar. (28 references) (Author/MES)

Retrospective determination of 137Cs specific activity distribution in spruce bark and bark aggregated transfer factor in forests on the scale of the Czech Republic ten years after the Chernobyl accident.

PubMed

Suchara, I; Rulík, P; Hůlka, J; Pilátová, H

2011-04-15

The (137)Cs specific activities (mean 32Bq kg(-1)) were determined in spruce bark samples that had been collected at 192 sampling plots throughout the Czech Republic in 1995, and were related to the sampling year. The (137)Cs specific activities in spruce bark correlated significantly with the (137)Cs depositions in areas affected by different precipitation sums operating at the time of the Chernobyl fallout in 1986. The ratio of the (137)Cs specific activities in bark and of the (137)Cs deposition levels yielded bark aggregated transfer factor T(ag) about 10.5×10(-3)m(-2)kg(-1). Taking into account the residual specific activities of (137)Cs in bark 20Bq kg(-1) and the available pre-Chernobyl data on the (137)Cs deposition loads on the soil surface in the Czech Republic, the real aggregated transfer factor after and before the Chernobyl fallout proved to be T*(ag)=3.3×10(-3)m(-2)kg(-1) and T**(ag)=4.0×10(-3)m(-2)kg(-1), respectively. The aggregated transfer factors T*(ag) for (137)Cs and spruce bark did not differ significantly in areas unequally affected by the (137)Cs fallout in the Czech Republic in 1986, and the figures for these aggregated transfer factors were very similar to the mean bark T(ag) values published from the extensively affected areas near Chernobyl. The magnitude of the (137)Cs aggregated transfer factors for spruce bark for the pre-Chernobyl and post-Chernobyl period in the Czech Republic was also very similar. The variability in spruce bark acidity caused by the operation of local anthropogenic air pollution sources did not significantly influence the accumulation and retention of (137)Cs in spruce bark. Increasing elevation of the bark sampling plots had a significant effect on raising the remaining (137)Cs specific activities in bark in areas affected by precipitation at the time when the plumes crossed, because the sums of this precipitation increased with elevation (covariable). Copyright © 2011 Elsevier B.V. All rights reserved.

Cardioprotection by controlling hyperamylinemia in a "humanized" diabetic rat model.

PubMed

Despa, Sanda; Sharma, Savita; Harris, Todd R; Dong, Hua; Li, Ning; Chiamvimonvat, Nipavan; Taegtmeyer, Heinrich; Margulies, Kenneth B; Hammock, Bruce D; Despa, Florin

2014-08-21

Chronic hypersecretion of the pancreatic hormone amylin is common in humans with obesity or prediabetic insulin resistance and induces amylin aggregation and proteotoxicity in the pancreas. We recently showed that hyperamylinemia also affects the cardiovascular system. Here, we investigated whether amylin aggregates interact directly with cardiac myocytes and whether controlling hyperamylinemia protects the heart. By Western blot, we found abundant amylin aggregates in lysates of cardiac myocytes from obese patients, but not in controls. Aggregated amylin was elevated in failing hearts, suggesting a role in myocyte injury. Using rats overexpressing human amylin in the pancreas (HIP rats) and control myocytes incubated with human amylin, we show that amylin aggregation at the sarcolemma induces oxidative stress and Ca(2+) dysregulation. In time, HIP rats developed cardiac hypertrophy and left-ventricular dilation. We then tested whether metabolites with antiaggregation properties, such as eicosanoid acids, limit myocardial amylin deposition. Rats were treated with an inhibitor of soluble epoxide hydrolase, the enzyme that degrades endogenous eicosanoids. Treatment doubled the blood concentration of eicosanoids, which drastically reduced incorporation of aggregated amylin in cardiac myocytes and blood cells, without affecting pancreatic amylin secretion. Animals in the treated group showed reduced cardiac hypertrophy and left-ventricular dilation. The cardioprotective mechanisms included the mitigation of amylin-induced cardiac oxidative stress and Ca(2+) dysregulation. The results suggest blood amylin as a novel therapeutic target in diabetic heart disease and elevating blood levels of antiaggregation metabolites as a pharmacological strategy to reduce amylin aggregation and amylin-mediated cardiotoxicity. © 2014 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

The effect of protein acetylation on the formation and processing of inclusion bodies and endogenous protein aggregates in Escherichia coli cells.

PubMed

Kuczyńska-Wiśnik, Dorota; Moruno-Algara, María; Stojowska-Swędrzyńska, Karolina; Laskowska, Ewa

2016-11-10

Acetylation of lysine residues is a reversible post-translational modification conserved from bacteria to humans. Several recent studies have revealed hundreds of lysine-acetylated proteins in various bacteria; however, the physiological role of these modifications remains largely unknown. Since lysine acetylation changes the size and charge of proteins and thereby may affect their conformation, we assumed that lysine acetylation can stimulate aggregation of proteins, especially for overproduced recombinant proteins that form inclusion bodies. To verify this assumption, we used Escherichia coli strains that overproduce aggregation-prone VP1GFP protein. We found that in ΔackA-pta cells, which display diminished protein acetylation, inclusion bodies were formed with a delay and processed faster than in the wild-type cells. Moreover, in ΔackA-pta cells, inclusion bodies exhibited significantly increased specific GFP fluorescence. In CobB deacetylase-deficient cells, in which protein acetylation was enhanced, the formation of inclusion bodies was increased and their processing was significantly inhibited. Similar results were obtained with regard to endogenous protein aggregates formed during the late stationary phase in ΔackA-pta and ΔcobB cells. Our studies revealed that protein acetylation affected the aggregation of endogenous E. coli proteins and the yield, solubility, and biological activity of a model recombinant protein. In general, decreased lysine acetylation inhibited the formation of protein aggregates, whereas increased lysine acetylation stabilized protein aggregates. These findings should be considered during the designing of efficient strategies for the production of recombinant proteins in E. coli cells.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riback, Joshua A.; Bowman, Micayla A.; Zmyslowski, Adam M.

A substantial fraction of the proteome is intrinsically disordered, and even well-folded proteins adopt non-native geometries during synthesis, folding, transport, and turnover. Characterization of intrinsically disordered proteins (IDPs) is challenging, in part because of a lack of accurate physical models and the difficulty of interpreting experimental results. We have developed a general method to extract the dimensions and solvent quality (self-interactions) of IDPs from a single small-angle x-ray scattering measurement. We applied this procedure to a variety of IDPs and found that even IDPs with low net charge and high hydrophobicity remain highly expanded in water, contrary to the generalmore » expectation that protein-like sequences collapse in water. Our results suggest that the unfolded state of most foldable sequences is expanded; we conjecture that this property was selected by evolution to minimize misfolding and aggregation.« less

A Theoretical Study of some Rheological Properties of the Aggregation of the Molecules Deoxy- Hemoglobin S

NASA Astrophysics Data System (ADS)

Mensah, Francis; Grant, Julius; Thorpe, Arthur

2010-02-01

Sickle cell disease is a serious public health problem that affects many people worldwide. In this paper, the Langevin equation is used for hemoglobin's aggregation in sickle cell anemia. Several parameters are explored such as the time-dependent deformation of the aggregates whose plot gives a sigmoid, the time-dependent expressions obtained for the coefficient of viscosity and the elastic modulus which characterize the aggregation of the sickle hemoglobin. Other properties such as the viscoelastic and the elasto-thixotropic properties of the sickle hemoglobin polymer are also described. An attempt is made to approach the polymerization process in terms of a dynamical system. )

Staff turnover in statewide implementation of ACT: relationship with ACT fidelity and other team characteristics

PubMed Central

Rollins, Angela L.; Salyers, Michelle P.; Tsai, Jack; Lydick, Jennifer M.

2010-01-01

Staff turnover on assertive community treatment (ACT) teams is a poorly understood phenomenon. This study examined annual turnover and fidelity data collected in a statewide implementation of ACT over a 5-year period. Mean annual staff turnover across all observations was 30.0%. Turnover was negatively correlated with overall fidelity at Year 1 and 3. The team approach fidelity item was negatively correlated with staff turnover at Year 3. For 13 teams with 3 years of follow-up data, turnover rates did not change over time. Most ACT staff turnover rates were comparable or better than other turnover rates reported in the mental health and substance abuse literature. PMID:20012481

Staff turnover in statewide implementation of ACT: relationship with ACT fidelity and other team characteristics.

PubMed

Rollins, Angela L; Salyers, Michelle P; Tsai, Jack; Lydick, Jennifer M

2010-09-01

Staff turnover on assertive community treatment (ACT) teams is a poorly understood phenomenon. This study examined annual turnover and fidelity data collected in a statewide implementation of ACT over a 5-year period. Mean annual staff turnover across all observations was 30.0%. Turnover was negatively correlated with overall fidelity at Year 1 and 3. The team approach fidelity item was negatively correlated with staff turnover at Year 3. For 13 teams with 3 years of follow-up data, turnover rates did not change over time. Most ACT staff turnover rates were comparable or better than other turnover rates reported in the mental health and substance abuse literature.

Factors That Affect Oxygen Activation and Coupling of the Two Redox Cycles in the Aromatization Reaction Catalyzed by NikD, an Unusual Amino Acid Oxidase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kommoju, Phaneeswara-Rao; Bruckner, Robert C.; Ferreira, Patricia

2009-10-21

NikD is a flavoprotein oxidase that catalyzes the oxidation of piperideine-2-carboxylate (P2C) to picolinate in a remarkable aromatization reaction comprising two redox cycles and at least one isomerization step. Tyr258 forms part of an 'aromatic cage' that surrounds the ring in picolinate and its precursors. Mutation of Tyr258 to Phe does not perturb the structure of nikD but does affect the coupling of the two redox cycles and causes a 10-fold decrease in turnover rate. Tyr258Phe catalyzes a quantitative two-electron oxidation of P2C, but only 60% of the resulting dihydropicolinate intermediate undergoes a second redox cycle to produce picolinate. Themore » mutation does not affect product yield with an alternate substrate (3,4-dehydro-l-proline) that is aromatized in a single two-electron oxidation step. Wild-type and mutant enzymes exhibit identical rate constants for oxidation of P2C to dihydropicolinate and isomerization of a reduced enzyme-dihydropicolinate complex. The observed rates are 200- and 10-fold faster, respectively, than the mutant turnover rate. Release of picolinate from Tyr258Phe is 100-fold faster than turnover. The presence of a bound substrate or product is a key factor in oxygen activation by wild-type nikD, as judged by the 10-75-fold faster rates observed for complexes of the reduced enzyme with picolinate, benzoate, or 1-cyclohexenoate, a 1-deaza-P2C analogue. The reduced Tyr258Phe-1-cyclohexenoate complex is 25-fold less reactive with oxygen than the wild-type complex. We postulate that mutation of Tyr258 causes subtle changes in active site dynamics that promote release of the reactive dihydropicolinate intermediate and disrupt the efficient synchronization of oxygen activation observed with wild-type nikD.« less

Perceived overqualification and its outcomes: the moderating role of empowerment.

PubMed

Erdogan, Berrin; Bauer, Talya N

2009-03-01

Research shows that perceived overqualification is related to lower job attitudes and greater withdrawal behaviors but to higher supervisor ratings of performance. Drawing upon relative deprivation theory, the authors proposed and tested empowerment as a moderator of the relationship between perceived overqualification and job satisfaction, intentions to remain, voluntary turnover, and objective sales performance to examine if negative outcomes could be lessened while stimulating even higher performance. Hierarchical linear modeling results from a sample of 244 sales associates working in 25 stores of a Turkish retail chain show that empowerment ameliorated the negative effects of perceived overqualification on job satisfaction, intentions to remain, and voluntary turnover. Empowerment did not affect the positive relationship between perceived overqualification and objective sales performance. (c) 2009 APA, all rights reserved.

Greater milk intake is associated with lower bone turnover, higher bone density, and higher bone microarchitecture index in a population of elderly Japanese men with relatively low dietary calcium intake: Fujiwara-kyo Osteoporosis Risk in Men (FORMEN) Study.

PubMed

Sato, Y; Iki, M; Fujita, Y; Tamaki, J; Kouda, K; Yura, A; Moon, J-S; Winzenrieth, R; Iwaki, H; Ishizuka, R; Amano, N; Tomioka, K; Okamoto, N; Kurumatani, N

2015-05-01

The effects of milk intake on bone health are not clear in elderly Asian men with low dietary calcium intake. This study showed that greater milk intake is associated with lower bone turnover, higher bone density, and higher bone microarchitecture index in community-dwelling elderly Japanese men. The consumption of milk or dairy products is widely recommended for maintaining bone health regardless of gender or age. However, little evidence exists on the beneficial effects of milk intake on bone health in elderly Japanese men characterized with relatively low dietary calcium intake. Here we examined whether or not greater milk intake was associated with lower bone turnover, higher bone density, and stronger bone microarchitecture in community-dwelling elderly Japanese men. Interviews were conducted to obtain information on medical history and lifestyle, including the amount of habitual milk intake, nutrient intake calculations based on a 1-week food diary, and measurements of areal bone mineral density (aBMD) at the lumbar spine (LS), total hip (TH), and femoral neck (FN) by dual-energy x-ray absorptiometry (DXA), trabecular bone score (TBS) using DXA images at LS, and biochemical markers of bone turnover in sera. Participants with a history of diseases or medications that affect bone metabolism, or with missing data, were excluded from the analysis. The median intake of milk in the 1479 participants (mean age, 73.0 ± 5.1 years) was one glass of milk per day. Bone turnover markers showed a decreasing trend (p < 0.05) and aBMD at TH (p = 0.0019) and FN (p = 0.0057) and TBS (p = 0.0017) showed increasing trends with greater milk intake after adjusting for demographic and behavioral confounding factors. This association was attenuated after further adjusting for nutrient intake, in particular, calcium intake. Greater milk intake was associated with lower bone turnover, higher aBMD, and higher TBS in community-dwelling elderly Japanese men.

β-Synuclein suppresses both the initiation and amplification steps of α-synuclein aggregation via competitive binding to surfaces

NASA Astrophysics Data System (ADS)

Brown, James W. P.; Buell, Alexander K.; Michaels, Thomas C. T.; Meisl, Georg; Carozza, Jacqueline; Flagmeier, Patrick; Vendruscolo, Michele; Knowles, Tuomas P. J.; Dobson, Christopher M.; Galvagnion, Céline

2016-11-01

α-Synuclein is an intrinsically disordered protein that is associated with the pathogenesis of Parkinson’s disease through the processes involved in the formation of amyloid fibrils. α and β-synuclein are homologous proteins found at comparable levels in presynaptic terminals but β-synuclein has a greatly reduced propensity to aggregate and indeed has been found to inhibit α-synuclein aggregation. In this paper, we describe how sequence differences between α- and β-synuclein affect individual microscopic processes in amyloid formation. In particular, we show that β-synuclein strongly suppresses both lipid-induced aggregation and secondary nucleation of α-synuclein by competing for binding sites at the surfaces of lipid vesicles and fibrils, respectively. These results suggest that β-synuclein can act as a natural inhibitor of α-synuclein aggregation by reducing both the initiation of its self-assembly and the proliferation of its aggregates.

Role of Different Alpha-Synuclein Strains in Synucleinopathies, Similarities with other Neurodegenerative Diseases

PubMed Central

Melki, Ronald

2015-01-01

Abstract Misfolded protein aggregates are the hallmark of several neurodegenerative diseases in humans. The main protein constituent of these aggregates and the regions within the brain that are affected differ from one neurodegenerative disorder to another. A plethora of reports suggest that distinct diseases have in common the ability of protein aggregates to spread and amplify within the central nervous system. This review summarizes briefly what is known about the nature of the protein aggregates that are infectious and the reason they are toxic to cells. The chameleon property of polypeptides which aggregation into distinct high-molecular weight assemblies is associated to different diseases, in particular, that of alpha-synuclein which aggregation is the hallmark of distinct synucleinopathies, is discussed. Finally, strategies targeting the formation and propagation of structurally distinct alpha-synuclein assemblies associated to different synucleinopathies are presented and their therapeutic and diagnostic potential is discussed. PMID:25757830

Glyceraldehyde-3-phosphate dehydrogenase aggregation inhibitor peptide: A potential therapeutic strategy against oxidative stress-induced cell death.

PubMed

Itakura, Masanori; Nakajima, Hidemitsu; Semi, Yuko; Higashida, Shusaku; Azuma, Yasu-Taka; Takeuchi, Tadayoshi

2015-11-13

The glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has multiple functions, including mediating oxidative stress-induced neuronal cell death. This process is associated with disulfide-bonded GAPDH aggregation. Some reports suggest a link between GAPDH and the pathogenesis of several oxidative stress-related diseases. However, the pathological significance of GAPDH aggregation in disease pathogenesis remains unclear due to the lack of an effective GAPDH aggregation inhibitor. In this study, we identified a GAPDH aggregation inhibitor (GAI) peptide and evaluated its biological profile. The decapeptide GAI specifically inhibited GAPDH aggregation in a concentration-dependent manner. Additionally, the GAI peptide did not affect GAPDH glycolytic activity or cell viability. The GAI peptide also exerted a protective effect against oxidative stress-induced cell death in SH-SY5Y cells. This peptide could potentially serve as a tool to investigate GAPDH aggregation-related neurodegenerative and neuropsychiatric disorders and as a possible therapy for diseases associated with oxidative stress-induced cell death. Copyright © 2015 Elsevier Inc. All rights reserved.

Cholesterol impairment contributes to neuroserpin aggregation

NASA Astrophysics Data System (ADS)

Giampietro, Costanza; Lionetti, Maria Chiara; Costantini, Giulio; Mutti, Federico; Zapperi, Stefano; La Porta, Caterina A. M.

2017-03-01

Intraneural accumulation of misfolded proteins is a common feature of several neurodegenerative pathologies including Alzheimer’s and Parkinson’s diseases, and Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB). FENIB is a rare disease due to a point mutation in neuroserpin which accelerates protein aggregation in the endoplasmic reticulum (ER). Here we show that cholesterol depletion induced either by prolonged exposure to statins or by inhibiting the sterol reg-ulatory binding-element protein (SREBP) pathway also enhances aggregation of neuroserpin proteins. These findings can be explained considering a computational model of protein aggregation under non-equilibrium conditions, where a decrease in the rate of protein clearance improves aggregation. Decreasing cholesterol in cell membranes affects their biophysical properties, including their ability to form the vesicles needed for protein clearance, as we illustrate by a simple mathematical model. Taken together, these results suggest that cholesterol reduction induces neuroserpin aggregation, even in absence of specific neuroserpin mutations. The new mechanism we uncover could be relevant also for other neurodegenerative diseases associated with protein aggregation.

Memantine inhibits β-amyloid aggregation and disassembles preformed β-amyloid aggregates.

PubMed

Takahashi-Ito, Kaori; Makino, Mitsuhiro; Okado, Keiko; Tomita, Taisuke

2017-11-04

Memantine, an uncompetitive glutamatergic N-methyl-d-aspartate (NMDA) receptor antagonist, is widely used as a medication for the treatment of Alzheimer's disease (AD). We previously reported that chronic treatment of AD with memantine reduces the amount of insoluble β-amyloid (Aβ) and soluble Aβ oligomers in animal models of AD. The mechanisms by which memantine reduces Aβ levels in the brain were evaluated by determining the effect of memantine on Aβ aggregation using thioflavin T and transmission electron microscopy. Memantine inhibited the formation of Aβ(1-42) aggregates in a concentration-dependent manner, whereas amantadine, a structurally similar compound, did not affect Aβ aggregation at the same concentrations. Furthermore, memantine inhibited the formation of different types of Aβ aggregates, including Aβs carrying familial AD mutations, and disaggregated preformed Aβ(1-42) fibrils. These results suggest that the inhibition of Aβ aggregation and induction of Aβ disaggregation may be involved in the mechanisms by which memantine reduces Aβ deposition in the brain. Copyright © 2017 Elsevier Inc. All rights reserved.

Atomistic Structure of Mineral Nano-aggregates from Simulated Compaction and Dewatering.

PubMed

Ho, Tuan Anh; Greathouse, Jeffery A; Wang, Yifeng; Criscenti, Louise J

2017-11-10

The porosity of clay aggregates is an important property governing chemical reactions and fluid flow in low-permeability geologic formations and clay-based engineered barrier systems. Pore spaces in clays include interlayer and interparticle pores. Under compaction and dewatering, the size and geometry of such pore spaces may vary significantly (sub-nanometer to microns) depending on ambient physical and chemical conditions. Here we report a molecular dynamics simulation method to construct a complex and realistic clay-like nanoparticle aggregate with interparticle pores and grain boundaries. The model structure is then used to investigate the effect of dewatering and water content on micro-porosity of the aggregates. The results suggest that slow dewatering would create more compact aggregates compared to fast dewatering. Furthermore, the amount of water present in the aggregates strongly affects the particle-particle interactions and hence the aggregate structure. Detailed analyses of particle-particle and water-particle interactions provide a molecular-scale view of porosity and texture development of the aggregates. The simulation method developed here may also aid in modeling the synthesis of nanostructured materials through self-assembly of nanoparticles.

Effect of lightweight aggregates prepared from fly ash on lightweight concrete performances

NASA Astrophysics Data System (ADS)

Punlert, S.; Laoratanakul, P.; Kongdee, R.; Suntako, R.

2017-09-01

Lightweight aggregates were prepared from fly ash of by-products from the paper industry. The influence of the ratio of clay to fly ash and processing conditions on lightweight aggregates properties were investigated. It was found that the amount of fly ash directly affected to porosity of lightweight aggregates. Lightweight aggregates with the ratio of clay to fly ash at 80:20 wt% using the sintering temperature at 1210°C exhibits bulk density of 1.66 g cm-3, compressive strength of 25 MPa and water absorption of 0.55%. The replacement of coarse aggregates with lightweight aggregates at 100 wt% for concrete production showed the ultimate properties of concrete with density of 1780 g cm-3, water absorption of 3.55%, compressive strength of 40.94 MPa and thermal conductivity of 0.77 W m-1K-1. The concrete had more than 25% weight reduction while keeping a similar compressive strength to an ordinary concrete. This is revealed that lightweight aggregates could be applied into structural concrete because it was able to reduce work load and increase safety factor of construction.

Atomistic Structure of Mineral Nano-aggregates from Simulated Compaction and Dewatering

DOE PAGES

Ho, Tuan Anh; Greathouse, Jeffery A.; Wang, Yifeng; ...

2017-11-10

The porosity of clay aggregates is an important property governing chemical reactions and fluid flow in low-permeability geologic formations and clay-based engineered barrier systems. Pore spaces in clays include interlayer and interparticle pores. Under compaction and dewatering, the size and geometry of such pore spaces may vary significantly (sub-nanometer to microns) depending on ambient physical and chemical conditions. Here we report a molecular dynamics simulation method to construct a complex and realistic clay-like nanoparticle aggregate with interparticle pores and grain boundaries. The model structure is then used to investigate the effect of dewatering and water content on micro-porosity of themore » aggregates. The results suggest that slow dewatering would create more compact aggregates compared to fast dewatering. Furthermore, the amount of water present in the aggregates strongly affects the particle-particle interactions and hence the aggregate structure. Detailed analyses of particle-particle and water-particle interactions provide a molecular-scale view of porosity and texture development of the aggregates. The simulation method developed here may also aid in modeling the synthesis of nanostructured materials through self-assembly of nanoparticles.« less

Differences in Bone Quality between High versus Low Turnover Renal Osteodystrophy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Porter, Daniel S.; Pienkowski, David; Faugere, Marie-Claude

2012-01-01

Abnormal bone turnover is common in chronic kidney disease (CKD), but its effects on bone quality remain unclear. This study sought to quantify the relationship between abnormal bone turnover and bone quality. Iliac crest bone biopsies were obtained from CKD-5 patients on dialysis with low (n=18) or high (n=17) turnover, and from volunteers (n=12) with normal turnover and normal kidney function. Histomorphometric methods were used to quantify the microstructural parameters; Fourier transform infrared spectroscopy and nanoindentation were used to quantify the material and mechanical properties in bone. Reduced mineral-to-matrix ratio, mineral crystal size, stiffness and hardness were observed in bonemore » with high turnover compared to bone with normal or low turnover. Decreased cancellous bone volume and trabecular thickness were seen in bone with low turnover compared to bone with normal or high turnover. Bone quality, as defined by its microstructural, material, and mechanical properties, is related to bone turnover. These data suggest that turnover related alterations in bone quality may contribute to the known diminished mechanical competence of bone in CKD patients, albeit from different mechanisms for bone with high (material abnormality) vs. low (microstructural alteration) turnover. The present findings suggest that improved treatments for renal osteodystrophy should seek to avoid low or high bone turnover and aim for turnover rates as close to normal as possible.« less

Turnover among Community Mental Health Workers in Ohio.

PubMed

Bukach, Ashley M; Ejaz, Farida K; Dawson, Nicole; Gitter, Robert J

2017-01-01

This study examined turnover of community mental health workers in 42 randomly selected mental health agencies in Ohio. The turnover rate in 2011 was 26 %. A regression analysis indicated that agencies with lower turnover offered higher maximum pay and were smaller in size, while those offering career advancement opportunities, such as career ladder programs, had higher turnover. The findings suggest that improving wages for workers is likely to reduce turnover. It is also possible that smaller agencies have lower turnover due to stronger relationships with workers and/or more successful hiring practices. Furthermore, turnover that occurs as a result of career advancement could have positive effects and should be examined separate from other types of turnover in the future.

The longitudinal study of turnover and the cost of turnover in emergency medical services.

PubMed

Patterson, P Daniel; Jones, Cheryl B; Hubble, Michael W; Carr, Matthew; Weaver, Matthew D; Engberg, John; Castle, Nicholas

2010-01-01

Few studies have examined employee turnover and associated costs in emergency medical services (EMS). To quantify the mean annual rate of turnover, total median cost of turnover, and median cost per termination in a diverse sample of EMS agencies. A convenience sample of 40 EMS agencies was followed over a six-month period. Internet, telephone, and on-site data-collection methods were used to document terminations, new hires, open positions, and costs associated with turnover. The cost associated with turnover was calculated based on a modified version of the Nursing Turnover Cost Calculation Methodology (NTCCM). The NTCCM identified direct and indirect costs through a series of questions that agency administrators answered monthly during the study period. A previously tested measure of turnover to calculate the mean annual rate of turnover was used. All calculations were weighted by the size of the EMS agency roster. The mean annual rate of turnover, total median cost of turnover, and median cost per termination were determined for three categories of agency staff mix: all-paid staff, mix of paid and volunteer (mixed) staff, and all-volunteer staff. The overall weighted mean annual rate of turnover was 10.7%. This rate varied slightly across agency staffing mix (all-paid = 10.2%, mixed = 12.3%, all-volunteer = 12.4%). Among agencies that experienced turnover (n = 25), the weighted median cost of turnover was $71,613.75, which varied across agency staffing mix (all-paid = $86,452.05, mixed = $9,766.65, and all-volunteer = $0). The weighted median cost per termination was $6,871.51 and varied across agency staffing mix (all-paid = $7,161.38, mixed = $1,409.64, and all-volunteer = $0). Annual rates of turnover and costs associated with turnover vary widely across types of EMS agencies. The study's mean annual rate of turnover was lower than expected based on information appearing in the news media and EMS trade magazines. Findings provide estimates of two key workforce measures--turnover rates and costs--where previously none have existed. Local EMS directors and policymakers at all levels of government may find the results and study methodology useful toward designing and evaluating programs targeting the EMS workforce.

Soil organic matter persistence as a stochastic process: age and transit time distributions of carbon in soils

NASA Astrophysics Data System (ADS)

Sierra, Carlos

2017-04-01

The question of why some organic matter is more persistent than other that decomposes quickly in soils has sparkled a large amount of research in recent years. Persistence is commonly characterized as the turnover or mean residence time of specific compounds or soil organic matter (SOM) pools. However, turnover and residence times are ambiguous measures of persistence, which is better characterized by the probability distribution of ages in the system and in particular pools. We calculated age distributions for a wide range of SOM models, which showed long-tail distributions far from the mean value. Age and transit time distributions from a variety of models also showed: 1) transit times are lower than ages of SOM, 2) turnover times differ significantly from mean ages in slow cycling pools, 3) change in the inputs, without changes in the allocation of photosynthetic products, has no effect on transit times, but does affect system and pool ages. We propose an index to assess persistence of C in soils that can be derived from observations alone or from models. We also ask whether random chance is an important contributor to the persistence of SOM.

Changes in floral diversities, floral turnover rates, and climates in Campanian and Maastrichtian time, North Slope of Alaska

USGS Publications Warehouse

Frederiksen, N.O.

1989-01-01

One-hundred-and-ten angiosperm pollen taxa have been found in upper Campanian to Masstrichtian rocks of the Colville River region, North Slope of Alaska. These are the highest paleolatitude Campanian and Maastrichtian floras known from North America. Total angiosperm pollen diversity rose during the Campanian and declined toward the end of the Maastrichtian. However, anemophilous porate pollen of the Betulaceae-Myricaceae-Ulmaceae complex increased gradually in diversity during the late Campanian and Maastrichtian and into the Paleocene. Turnover of angiosperm taxa was active throughout most of late Campanian and Maastrichtian time; rapid turnover affected mainly the taxa of zoophilous herbs, representing an bundant but ecologically subordinate element of the vegetation. Last appearances of pollen taxa during the late Campanian and Maastrichtian probably represented mainly extinctions rather than emigrations; end- Cretaceous angiosperm extinctions in the North American Arctic began well before the Cretaceous-Tertiary boundary event. The last appearances in the late Maastrichtian took place in bursts; they appear to represent stepwise rather than gradual events, which may indicate the existence of pulses of climatic change particularly in late Maastrichtian time. ?? 1989.

Turnover of regulated nurses in long-term care facilities.

PubMed

Chu, Charlene H; Wodchis, Walter P; McGilton, Katherine S

2014-07-01

To describe the relationship between nursing staff turnover in long-term care (LTC) homes and organisational factors consisting of leadership practices and behaviours, supervisory support, burnout, job satisfaction and work environment satisfaction. The turnover of regulated nursing staff [Registered Nurses (RNs) and Registered Practical Nurses (RPNs)] in LTC facilities is a pervasive problem, but there is a scarcity of research examining this issue in Canada. The study was conceptualized using a Stress Process model. Distinct surveys were distributed to administrators to measure organisational factors and to regulated nurses to measure personal and job-related sources of stress and workplace support. In total, 324 surveys were used in the linear regression analysis to examine factors associated with high turnover rates. Higher leadership practice scores were associated with lower nursing turnover; a one score increase in leadership correlated with a 49% decrease in nursing turnover. A significant inverse relationship between leadership turnover and nurse turnover was found: the higher the administrator turnover the lower the nurse turnover rate. Leadership practices and administrator turnover are significant in influencing regulated nurse turnover in LTC. Long-term care facilities may want to focus on building good leadership and communication as an upstream method to minimize nurse turnover. © 2013 John Wiley & Sons Ltd.

Timescales alter the inferred strength and temporal consistency of intraspecific diet specialization

USGS Publications Warehouse

Novak, Mark; Tinker, M. Tim

2015-01-01

Many populations consist of individuals that differ substantially in their diets. Quantification of the magnitude and temporal consistency of such intraspecific diet variation is needed to understand its importance, but the extent to which different approaches for doing so reflect instantaneous vs. time-aggregated measures of individual diets may bias inferences. We used direct observations of sea otter individuals (Enhydra lutris nereis) to assess how: (1) the timescale of sampling, (2) under-sampling, and (3) the incidence- vs. frequency-based consideration of prey species affect the inferred strength and consistency of intraspecific diet variation. Analyses of feeding observations aggregated over hourly to annual intervals revealed a substantial bias associated with time aggregation that decreases the inferred magnitude of specialization and increases the inferred consistency of individuals’ diets. Time aggregation also made estimates of specialization more sensitive to the consideration of prey frequency, which decreased estimates relative to the use of prey incidence; time aggregation did not affect the extent to which under-sampling contributed to its overestimation. Our analyses demonstrate the importance of studying intraspecific diet variation with an explicit consideration of time and thereby suggest guidelines for future empirical efforts. Failure to consider time will likely produce inconsistent predictions regarding the effects of intraspecific variation on predator–prey interactions.

Curcumin and kaempferol prevent lysozyme fibril formation by modulating aggregation kinetic parameters.

PubMed

Borana, Mohanish S; Mishra, Pushpa; Pissurlenkar, Raghuvir R S; Hosur, Ramakrishna V; Ahmad, Basir

2014-03-01

Interaction of small molecule inhibitors with protein aggregates has been studied extensively, but how these inhibitors modulate aggregation kinetic parameters is little understood. In this work, we investigated the ability of two potential aggregation inhibiting drugs, curcumin and kaempferol, to control the kinetic parameters of aggregation reaction. Using thioflavin T fluorescence and static light scattering, the kinetic parameters such as amplitude, elongation rate constant and lag time of guanidine hydrochloride-induced aggregation reactions of hen egg white lysozyme were studied. We observed a contrasting effect of inhibitors on the kinetic parameters when aggregation reactions were measured by these two probes. The interactions of these inhibitors with hen egg white lysozyme were investigated using fluorescence quench titration method and molecular dynamics simulations coupled with binding free energy calculations. We conclude that both the inhibitors prolong nucleation of amyloid aggregation through binding to region of the protein which is known to form the core of the protein fibril, but once the nucleus is formed the rate of elongation is not affected by the inhibitors. This work would provide insight into the mechanism of aggregation inhibition by these potential drug molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Amyloidogenic Regions and Interaction Surfaces Overlap in Globular Proteins Related to Conformational Diseases

PubMed Central

Castillo, Virginia; Ventura, Salvador

2009-01-01

Protein aggregation underlies a wide range of human disorders. The polypeptides involved in these pathologies might be intrinsically unstructured or display a defined 3D-structure. Little is known about how globular proteins aggregate into toxic assemblies under physiological conditions, where they display an initially folded conformation. Protein aggregation is, however, always initiated by the establishment of anomalous protein-protein interactions. Therefore, in the present work, we have explored the extent to which protein interaction surfaces and aggregation-prone regions overlap in globular proteins associated with conformational diseases. Computational analysis of the native complexes formed by these proteins shows that aggregation-prone regions do frequently overlap with protein interfaces. The spatial coincidence of interaction sites and aggregating regions suggests that the formation of functional complexes and the aggregation of their individual subunits might compete in the cell. Accordingly, single mutations affecting complex interface or stability usually result in the formation of toxic aggregates. It is suggested that the stabilization of existing interfaces in multimeric proteins or the formation of new complexes in monomeric polypeptides might become effective strategies to prevent disease-linked aggregation of globular proteins. PMID:19696882

Compartmentalization of superoxide dismutase 1 (SOD1G93A) aggregates determines their toxicity

PubMed Central

Weisberg, Sarah J.; Lyakhovetsky, Roman; Werdiger, Ayelet-chen; Gitler, Aaron D.; Soen, Yoav; Kaganovich, Daniel

2012-01-01

Neurodegenerative diseases constitute a class of illnesses marked by pathological protein aggregation in the brains of affected individuals. Although these disorders are invariably characterized by the degeneration of highly specific subpopulations of neurons, protein aggregation occurs in all cells, which indicates that toxicity arises only in particular cell biological contexts. Aggregation-associated disorders are unified by a common cell biological feature: the deposition of the culprit proteins in inclusion bodies. The precise function of these inclusions remains unclear. The starting point for uncovering the origins of disease pathology must therefore be a thorough understanding of the general cell biological function of inclusions and their potential role in modulating the consequences of aggregation. Here, we show that in human cells certain aggregate inclusions are active compartments. We find that toxic aggregates localize to one of these compartments, the juxtanuclear quality control compartment (JUNQ), and interfere with its quality control function. The accumulation of SOD1G93A aggregates sequesters Hsp70, preventing the delivery of misfolded proteins to the proteasome. Preventing the accumulation of SOD1G93A in the JUNQ by enhancing its sequestration in an insoluble inclusion reduces the harmful effects of aggregation on cell viability. PMID:22967507

Does the Level of Occupational Aggregation Affect Estimates of the Gender Wage Gap?

ERIC Educational Resources Information Center

Kidd, Michael P.; Shannon, Michael

1996-01-01

Using data from the 1989 Canadian Labour-Market Activity Survey, when occupation is treated as a productivity-related characteristic, gender wage gap estimates are distorted. Using a larger number of occupations, the occupational aggregation by gender reflects barriers women face in attempting to enter male-dominated occupations. (SK)

Job Demand and Job Satisfaction in Latent Groups of Turnover Intention Among Licensed Nurses in Taiwan Nursing Homes.

PubMed

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.

The costs of nurse turnover: part 1: an economic perspective.

PubMed

Jones, Cheryl Bland

2004-12-01

Nurse turnover is costly for healthcare organizations. Administrators and nurse executives need a reliable estimate of nurse turnover costs and the origins of those costs if they are to develop effective measures of reducing nurse turnover and its costs. However, determining how to best capture and quantify nurse turnover costs can be challenging. Part 1 of this series conceptualizes nurse turnover via human capital theory and presents an update of a previously developed method for determining the costs of nurse turnover, the Nursing Turnover Cost Calculation Method. Part 2 (January 2005) presents a recent application of the methodology in an acute care hospital.

Lanosterol reverses protein aggregation in cataracts.

PubMed

Zhao, Ling; Chen, Xiang-Jun; Zhu, Jie; Xi, Yi-Bo; Yang, Xu; Hu, Li-Dan; Ouyang, Hong; Patel, Sherrina H; Jin, Xin; Lin, Danni; Wu, Frances; Flagg, Ken; Cai, Huimin; Li, Gen; Cao, Guiqun; Lin, Ying; Chen, Daniel; Wen, Cindy; Chung, Christopher; Wang, Yandong; Qiu, Austin; Yeh, Emily; Wang, Wenqiu; Hu, Xun; Grob, Seanna; Abagyan, Ruben; Su, Zhiguang; Tjondro, Harry Christianto; Zhao, Xi-Juan; Luo, Hongrong; Hou, Rui; Jefferson, J; Perry, P; Gao, Weiwei; Kozak, Igor; Granet, David; Li, Yingrui; Sun, Xiaodong; Wang, Jun; Zhang, Liangfang; Liu, Yizhi; Yan, Yong-Bin; Zhang, Kang

2015-07-30

The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.

Putrescine overproduction does not affect the catabolism of spermidine and spermine in poplar and Arabidopsis

Treesearch

Lin Shao; Pratiksha Bhatnagar; Rajtilak Majumdar; Rakesh Minocha; Subhash C. Minocha

2014-01-01

The effect of up-regulation of putrescine (Put) production by genetic manipulation on the turnover of spermidine (Spd) and spermine (Spm) was investigated in transgenic cells of poplar (Populus nigra x maximowiczii) and seedlings of Arabidopsis thaliana. Several-fold increase in Put production was achieved by expressing a mouse...

A Conceptual Model of a Research Design about Congruence between Environmental Turbulence, Strategic Aggressiveness, and General Management Capability in Community Colleges

ERIC Educational Resources Information Center

Lewis, Alfred

2013-01-01

Numerous studies have examined the determinant strategic elements that affect the performance of organizations. These studies have increasing relevance to community colleges because of the accelerating pace of change in enrollment, resource availability, leadership turnover, and demand for service that these institutions are experiencing. The…

Factors That Affect Retention of Novice Teachers in Hard-to-Staff High Schools in Virginia

ERIC Educational Resources Information Center

Blunt, Mechelle Savedge

2013-01-01

The mobility rates within the Kindergarten-Grade 12 teacher workforce are distressing, and the teaching profession has a relatively high turnover rate compared to other occupations. The Commonwealth of Virginia encounters many challenges when attempting to retain highly qualified teachers in schools. Despite the state's efforts to staff all…

An Anti-Bullying Training Course for Adults

ERIC Educational Resources Information Center

Ridgeway, Richard

2012-01-01

Workplace bullying is a phenomenon that is currently affecting as many as 70% of the workforce in the United States (Lutgen-Sandvic & McDermott, 2011). This phenomenon decreases morale, increases turn-over, and could soon lead to massive and costly litigation. In response to this I have proposed a two hour training course meant to educate workers…

Factors Affecting the Turnover of Different Groups of Part-Time Workers

ERIC Educational Resources Information Center

Senter, Jenell L.; Martin, James E.

2007-01-01

Past research on employee attitudes and behavior has focused mainly on full-time employees. When part-time employees have been studied, the research has concentrated on the differences between full-time and part-time employees. Recent research has suggested that part-time employees should not be viewed as a single, undifferentiated group. Instead…

Hope in Adolescent Careers: Mediating Effects of Work Motivation on Career Outcomes in Swiss Apprentices

ERIC Educational Resources Information Center

Valero, Domingo; Hirschi, Andreas; Strauss, Karoline

2015-01-01

Being hopeful is critical for individuals who are engaged in vocational pursuits. However, the empirical research examining how and why hope is related to work and career outcomes remains sparse. We evaluate a model that proposes that dispositional hope affects job performance and turnover intentions through increased work motivation in terms of…

40 CFR 60.393 - Performance test and compliance provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... per volume of applied coating solids (G) during each calendar month for each affected facility by the following equation: EC16NO91.030 (E) For each EDP prime coat operation, calculate the turnover ratio (RT) by....392(a). (ii) If the volume weighted average mass of VOC per volume of applied coating solids (G...

MMP-2, MMP-9, and TIMP-4 and Response to Aspirin in Diabetic and Nondiabetic Patients with Stable Coronary Artery Disease: A Pilot Study

PubMed Central

Kuliczkowski, Wiktor; Radomski, Marek; Gąsior, Mariusz; Urbaniak, Joanna; Kaczmarski, Jacek; Mysiak, Andrzej; Negrusz-Kawecka, Marta

2017-01-01

Background High on-aspirin treatment platelets reactivity (HPR) is a significant problem in long-term secondary prevention of cardiovascular events. We hypothesize that imbalance between platelets MMPs/TIMPs results in cardiovascular disorders. We also explored whether chronically elevated blood glucose affects MMP-2/TIMP-4 release from platelets. Materials and Methods Seventy patients with stable coronary artery disease, supplemented with aspirin, participated in this pilot study. The presence of HPR and/or diabetes mellitus was considered as the differentiating factor. Light aggregometry, impedance aggregometry, and ELISA tests for TXB2, MMP-2, MMP-9, and TIMP-4 were performed in serum, plasma, platelet-rich plasma, and platelets-poor plasma, as appropriate. Results Aspirin-HPR did not affect plasma MMP-2, MMP-9, and TIMP-4. Arachidonic acid-induced aggregation of platelets from aspirin-HPR patients did not lead to increased release of MMP-2, MMP-9, and TIMP-4. Studying patients at the lowest TXB2 serum concentration quartile revealed that high concentration of plasma TIMP-4 and TIMP-4 negatively correlated with TXB2 and platelet aggregation. Diabetics showed an increased plasma MMP-2 as well as an increased MMP-2 in supernatants after platelet aggregation. However, diabetes mellitus did not affect MMP-9 and TIMP-4. Conclusion Aspirin-HPR did not affect the translocation and release of MMPs and TIMP-4 from platelets. TIMP-4 may serve as a marker of TXA2-mediated platelet aggregation. Chronically elevated plasma glucose increases plasma MMP-2, and HPR potentiates this phenomenon. PMID:28770228

Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol

NASA Astrophysics Data System (ADS)

Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

2016-12-01

Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5-2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared.

Mechanical Performance Evaluation of Self-Compacting Concrete with Fine and Coarse Recycled Aggregates from the Precast Industry.

PubMed

Santos, Sara A; da Silva, Pedro R; de Brito, Jorge

2017-08-04

This paper intends to evaluate the feasibility of reintroducing recycled concrete aggregates in the precast industry. The mechanical properties of self-compacting concrete (SCC) with incorporation of recycled aggregates (RA) (coarse recycled aggregates (CRA) and fine recycled aggregates (FRA)) from crushed precast elements were evaluated. The goal was to evaluate the ability of producing SCC with a minimum pre-established performance in terms of mechanical strength, incorporating variable ratios of RA (FRA/CRA%: 0/0%, 25/25%, 50/50%, 0/100% and 100/0%) produced from precast source concretes with similar target performances. This replication in SCC was made for two strength classes (45 MPa and 65 MPa), with the intention of obtaining as final result concrete with recycled aggregates whose characteristics are compatible with those of a SCC with natural aggregates in terms of workability and mechanical strength. The results enabled conclusions to be established regarding the SCC's produced with fine and coarse recycled aggregates from the precast industry, based on its mechanical properties. The properties studied are strongly affected by the type and content of recycled aggregates. The potential demonstrated, mainly in the hardened state, by the joint use of fine and coarse recycled aggregate is emphasized.

Mechanical Performance Evaluation of Self-Compacting Concrete with Fine and Coarse Recycled Aggregates from the Precast Industry

PubMed Central

Santos, Sara A.; da Silva, Pedro R.; de Brito, Jorge

2017-01-01

This paper intends to evaluate the feasibility of reintroducing recycled concrete aggregates in the precast industry. The mechanical properties of self-compacting concrete (SCC) with incorporation of recycled aggregates (RA) (coarse recycled aggregates (CRA) and fine recycled aggregates (FRA)) from crushed precast elements were evaluated. The goal was to evaluate the ability of producing SCC with a minimum pre-established performance in terms of mechanical strength, incorporating variable ratios of RA (FRA/CRA%: 0/0%, 25/25%, 50/50%, 0/100% and 100/0%) produced from precast source concretes with similar target performances. This replication in SCC was made for two strength classes (45 MPa and 65 MPa), with the intention of obtaining as final result concrete with recycled aggregates whose characteristics are compatible with those of a SCC with natural aggregates in terms of workability and mechanical strength. The results enabled conclusions to be established regarding the SCC’s produced with fine and coarse recycled aggregates from the precast industry, based on its mechanical properties. The properties studied are strongly affected by the type and content of recycled aggregates. The potential demonstrated, mainly in the hardened state, by the joint use of fine and coarse recycled aggregate is emphasized. PMID:28777316

Effect of saliva viscosity on the co-aggregation between oral streptococci and Actinomyces naeslundii.

PubMed

Kitada, Katsuhiro; Oho, Takahiko

2012-06-01

The co-aggregation of oral bacteria leads to their clearance from the oral cavity. Poor oral hygiene and high saliva viscosity are common amongst the elderly; thus, they frequently suffer from pneumonia caused by the aspiration of oral microorganisms. To examine the direct effect of saliva viscosity on the co-aggregation of oral streptococci with actinomyces. Fifteen oral streptococcal and a single actinomyces strain were used. Co-aggregation was assessed by a visual assay in phosphate buffer and a spectrophotometric assay in the same buffer containing 0-60% glycerol or whole saliva. Nine oral streptococci co-aggregated with Actinomyces naeslundii ATCC12104 in the visual assay and were subsequently used for the spectrophotometric analysis. All tested strains displayed a decrease in co-aggregation with increasing amounts of glycerol in the buffer. The co-aggregation of Streptococcus oralis with A. naeslundii recovered to baseline level following the removal of glycerol. The per cent co-aggregation of S. oralis with A. naeslundii was significantly correlated with the viscosity in unstimulated and stimulated whole saliva samples (correlation coefficients: -0.52 and -0.48, respectively). This study suggests that saliva viscosity affects the co-aggregation of oral streptococci with actinomyces and that bacterial co-aggregation decreases with increasing saliva viscosity. © 2011 The Gerodontology Society and John Wiley & Sons A/S.

Soil aggregation and aggregating agents as affected by long term contrasting management of an Anthrosol

PubMed Central

Zhang, Shulan; Wang, Renjie; Yang, Xueyun; Sun, Benhua; Li, Qinghui

2016-01-01

Soil aggregation was studied in a 21-year experiment conducted on an Anthrosol. The soil management regimes consisted of cropland abandonment, bare fallow without vegetation and cropping system. The cropping system was combined with the following nutrient management treatments: control (CONTROL, no nutrient input); nitrogen, phosphorus and potassium (NPK); straw plus NPK (SNPK); and manure (M) plus NPK (MNPK). Compared with the CONTROL treatment, the abandonment treatment significantly increased the formation of large soil macroaggregates (>2 mm) and consequently improved the stability of aggregates in the surface soil layer due to enhancement of hyphal length and of soil organic matter content. However, in response to long-term bare fallow treatment aggregate stability was low, as were the levels of aggregating agents. Long term fertilization significantly redistributed macroaggregates; this could be mainly ascribed to soil organic matter contributing to the formation of 0.5–2 mm classes of aggregates and a decrease in the formation of the >2 mm class of aggregates, especially in the MNPK treatment. Overall, hyphae represented a major aggregating agent in both of the systems tested, while soil organic compounds played significantly different roles in stabilizing aggregates in Anthrosol when the cropping system and the soil management regimes were compared. PMID:27958366

A study in cost analysis of aggregate production as depending on drilling and blasting design

NASA Astrophysics Data System (ADS)

Bilim, Niyazi; Çelik, Arif; Kekeç, Bilgehan

2017-10-01

Since aggregate production has vital importance for many engineering projects-such as construction, highway and plant-mixed concrete production-this study was undertaken to determine how the costs for such production are affected by the design of drilling and blasting processes used. Aggregates are used in the production of concrete and asphalt, which are critical resources for the construction sector. The ongoing population increase and the growth of living standards around the world drive the increasing demand for these products. As demand grows, competition has naturally arisen among producers in the industry. Competition in the market has directly affected prices, which leads to the need for new measures and cost analysis on production costs. The cost calculation is one of the most important parameters in mining activities. Aggregate production operations include drilling, blasting, secondary crushing (if necessary), loading, hauling and crushing-screening, and each of these factors affects cost. In this study, drilling and blasting design parameters (such as hole diameter, hole depth, hole distance and burden) were investigated and evaluated for their effect on the total cost of quarrying these products, based on a particular quarry selected for this research. As the result of evaluation, the parameters actually driving costs have been identified, and their effects on the cost have been determined. In addition, some suggestions are presented regarding production design which may lead to avoiding increased production costs.

Explaining Differences in Subjective Well-Being Across 33 Nations Using Multilevel Models: Universal Personality, Cultural Relativity, and National Income.

PubMed

Cheng, Cecilia; Cheung, Mike W-L; Montasem, Alex

2016-02-01

This multinational study simultaneously tested three prominent hypotheses--universal disposition, cultural relativity, and livability--that explained differences in subjective well-being across nations. We performed multilevel structural equation modeling to examine the hypothesized relationships at both individual and cultural levels in 33 nations. Participants were 6,753 university students (2,215 men; 4,403 women; 135 did not specify), and the average age of the entire sample was 20.97 years (SD = 2.39). Both individual- and cultural-level analyses supported the universal disposition and cultural relativity hypotheses by revealing significant associations of subjective well-being with Extraversion, Neuroticism, and independent self-construal. In addition, interdependent self-construal was positively related to life satisfaction at the individual level only, whereas aggregated negative affect was positively linked with aggregate levels of Extraversion and interdependent self-construal at the cultural level only. Consistent with the livability hypothesis, gross national income (GNI) was related to aggregate levels of negative affect and life satisfaction. There was also a quadratic relationship between GNI and aggregated positive affect. Our findings reveal that universal disposition, cultural self-construal, and national income can elucidate differences in subjective well-being, but the multilevel analyses advance the literature by yielding new findings that cannot be identified in studies using individual-level analyses alone. © 2014 Wiley Periodicals, Inc.

Efficient chemical and visible-light-driven water oxidation using nickel complexes and salts as precatalysts.

PubMed

Chen, Gui; Chen, Lingjing; Ng, Siu-Mui; Lau, Tai-Chu

2014-01-01

Chemical and visible-light-driven water oxidation catalyzed by a number of Ni complexes and salts have been investigated at pH 7-9 in borate buffer. For chemical oxidation, [Ru(bpy)3](3+) (bpy = 2,2'-bipyridine) was used as the oxidant, with turnover numbers (TONs) >65 and a maximum turnover frequency (TOFmax) >0.9 s(-1). Notably, simple Ni salts such as Ni(NO3 )2 are more active than Ni complexes that bear multidentate N-donor ligands. The Ni complexes and salts are also active catalysts for visible-light-driven water oxidation that uses [Ru(bpy)3](2+) as the photosensitizer and S2 O8 (2-) as the sacrificial oxidant; a TON>1200 was obtained at pH 8.5 by using Ni(NO3)2 as the catalyst. Dynamic light scattering measurements revealed the formation of nanoparticles in chemical and visible-light-driven water oxidation by the Ni catalysts. These nanoparticles aggregated during water oxidation to form submicron particles that were isolated and shown to be partially reduced β-NiOOH by various techniques, which include SEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, XRD, and IR spectroscopy. These results suggest that the Ni complexes and salts act as precatalysts that decompose under oxidative conditions to form an active nickel oxide catalyst. The nature of this active oxide catalyst is discussed. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Patient Turnover: A Concept Analysis.

PubMed

VanFosson, Christopher A; Yoder, Linda H; Jones, Terry L

Patient turnover influences the quality and safety of patient care. However, variations in the conceptual underpinnings of patient turnover limit the understanding of the phenomenon. A concept analysis was completed to clarify the role of patient turnover in relation to outcomes in the acute care hospital setting. The defining attributes, antecedents, consequences, and empirical referents of patient turnover were proposed. Nursing leaders should account for patient turnover in workload and staffing calculations. Further research is needed to clarify the influence of patient turnover on the quality and safety of nursing care using a unified understanding of the phenomenon.

Effect of degassing on the aggregation of carbon nanotubes dispersed in water

NASA Astrophysics Data System (ADS)

Chen, C.-J.; Huang, J.-R.; Hwang, I.-S.; Choi, H. J.; Lai, P.-Y.; Chan, C. K.

2017-10-01

Dynamic light scattering (DLS) along with centrifugation and shaking tests reveal that dissolved gases can significantly affect the aggregation behavior of carbon nanotubes (CNTs) dispersed in water. The CNTs in non-degassed samples form loose, stable networks having the DLS result reminiscent of semidilute polymer solutions, whereas the CNTs in degassed samples aggregate to form Brownian colloids that sediment quickly. Interestingly, the CNTs dispersed in acetone, with or without degassing, also behave like semidilute polymers in DLS experiments. We propose a surface nanobubble-assisted mechanism to explain the observed aggregation behaviors. Our work signifies that dissolved gases may play an important role in determining hydrophobicity and biomolecular functions in aqueous environments.

On the radiative properties of soot aggregates part 1: Necking and overlapping

NASA Astrophysics Data System (ADS)

Yon, J.; Bescond, A.; Liu, F.

2015-09-01

There is a strong interest in accurately modelling the radiative properties of soot aggregates (also known as black carbon particles) emitted from combustion systems and fires to gain improved understanding of the role of black carbon to global warming. This study conducted a systematic investigation of the effects of overlapping and necking between neighbouring primary particles on the radiative properties of soot aggregates using the discrete dipole approximation. The degrees of overlapping and necking are quantified by the overlapping and necking parameters. Realistic soot aggregates were generated numerically by constructing overlapping and necking to fractal aggregates formed by point-touch primary particles simulated using a diffusion-limited cluster aggregation algorithm. Radiative properties (differential scattering, absorption, total scattering, specific extinction, asymmetry factor and single scattering albedo) were calculated using the experimentally measured soot refractive index over the spectral range of 266-1064 nm for 9 combinations of the overlapping and necking parameters. Overlapping and necking affect significantly the absorption and scattering properties of soot aggregates, especially in the near UV spectrum due to the enhanced multiple scattering effects within an aggregate. By using correctly modified aggregate properties (fractal dimension, prefactor, primary particle radius, and the number of primary particle) and by accounting for the effects of multiple scattering, the simple Rayleigh-Debye-Gans theory for fractal aggregates can reproduce reasonably accurate radiative properties of realistic soot aggregates.

Integrating Ecosystem Engineering and Food Web Ecology: Testing the Effect of Biogenic Reefs on the Food Web of a Soft-Bottom Intertidal Area

PubMed Central

De Smet, Bart; Fournier, Jérôme; De Troch, Marleen; Vincx, Magda; Vanaverbeke, Jan

2015-01-01

The potential of ecosystem engineers to modify the structure and dynamics of food webs has recently been hypothesised from a conceptual point of view. Empirical data on the integration of ecosystem engineers and food webs is however largely lacking. This paper investigates the hypothesised link based on a field sampling approach of intertidal biogenic aggregations created by the ecosystem engineer Lanice conchilega (Polychaeta, Terebellidae). The aggregations are known to have a considerable impact on the physical and biogeochemical characteristics of their environment and subsequently on the abundance and biomass of primary food sources and the macrofaunal (i.e. the macro-, hyper- and epibenthos) community. Therefore, we hypothesise that L. conchilega aggregations affect the structure, stability and isotopic niche of the consumer assemblage of a soft-bottom intertidal food web. Primary food sources and the bentho-pelagic consumer assemblage of a L. conchilega aggregation and a control area were sampled on two soft-bottom intertidal areas along the French coast and analysed for their stable isotopes. Despite the structural impacts of the ecosystem engineer on the associated macrofaunal community, the presence of L. conchilega aggregations only has a minor effect on the food web structure of soft-bottom intertidal areas. The isotopic niche width of the consumer communities of the L. conchilega aggregations and control areas are highly similar, implying that consumer taxa do not shift their diet when feeding in a L. conchilega aggregation. Besides, species packing and hence trophic redundancy were not affected, pointing to an unaltered stability of the food web in the presence of L. conchilega. PMID:26496349

Soil aggregates, organic matter turnover and carbon balance in a Mediterranean eroded vineyard

NASA Astrophysics Data System (ADS)

Novara, Agata; Lo Papa, Giuseppe; Dazzi, Carmelo; Gristina, Luciano; Cerdà, Artemi

2014-05-01

The carbon cycle is being affected by the human impacts (Novara et al., 2011; Yan-Gui et al., 2013), and one of those is the intensification in the soil erosion in agriculture land (Cerdà et al., 2009; García Orenes et al., 2009). Vineyards also are affected by the human activities (Fernández Calviño, 2012). Vineyards in Sicily are cultivated on 110.000 ha, 10% of which on >10% slope. Deficiencies of soil organic matter are typical of the semi arid Mediterranean environment especially where traditional intensive cropping practices are adopted (Novara et al., 2012; 2013). These practices in vineyards could lead soil to intensive erosion processes (Novara et al., 2011). The fate of SOC under erosion processes is difficult to understand because of the influence of the erosion impact on SOC pathway, which depends on the different features of the process involved (detachment, transport and/or deposition). Soil erosion must be considered a net C source (Lal, 2003), as eroded soils have lower net primary productivity (NPP) (Dick and Gregorich, 2004) caused by reduction in the effective rooting depth and all in all determining decline in soil quality. Breakdown of aggregates and soil dispersion expose SOM to microbial/enzymatic processes and chemical soil properties (Dimoyiannis, 2012; Kocyigit and Demirci, 2012). Moreover the light fraction, transported by runoff, is labile and easily mineralized determining CO2 emission in the atmosphere (Jacinthe and Lal, 2004). Therefore, the carbon pool is lower in eroded than in un-eroded soil scapes and the rate of mineralization of soil organic matter is higher in sediments than in original soil. In this survey we show a research conducted on a slope sequence of three soil profiles in an irrigated vineyard located in Sambuca di Sicilia, Italy (UTM33-WGS84: 4169367N; 325011E). The SOC content was measured at depth intervals of 10 cm up to a depth of 60 cm in each pedon. Wet aggregate-size fractions with no prior chemical dispersion, were isolated by mechanical shaking of 100 g, air-dried fine earth on a column with sieves of 250 and 63 μm using a Shaker AS 200 Sieve (RETSCH analytical, Haan, Germany) (200-mm sieves, amplitude of 2 cm, frequency of 1.6 Hz and a water flux of 2 litres minute-1). After the physical fractionation, we discriminate three main aggregate-size fractions: >250, 63-250 and <63 μm. Three replicate samples of 5 g of the soil material that we prepared for the fractionation from three different pedons along the slope gradient were incubated at two different depth intervals (Topsoil: 0-15 cm; Subsoil: 35-50 cm). Respiration was monitored during a period of 50 days keeping moisture and temperature constant. Both in topsoil and subsoil layers, particle size distribution in the depositional area shows a decrease of the finest size (<63 μm) respect to the soil in the detachment area. A SOC increase was observed due to depositional processes. Mean Residence Time of SOC strongly decreased in the subsoil particularly in the depositional area corroborating that erosion processes could be a SOC sink. Anyway we should also stress that, considering the estimated "off farm" erosion processes, the carbon budget resulted highly negative. References Barbera, V., Poma, I., Gristina, L., Novara, A., Egli, M. 2013. Long-term cropping systems and tillage management effects on soil organic carbon stock and steady state level of C sequestration rates in a semiarid environment. Land Degradation & Development, 23: 82- 91. DOI 10.1002/ldr.1055 Cerdà, A., Giménez-Morera, A.G., Bodí, M.B. 2009b. Soil and water losses from new citrus orchards growing on sloped soils in the western Mediterranean basin. Earth Surface Processes and Landforms 34, 1822-1830. Dick, W.A., Gregorich, E.G. 2004. Developing and maintaining soil organic matter levels. In: Schjonning, P., Elmholt,S., Christensen, B.T. (Eds.), Managing Soil Quality: Challenges in Modern Agriculture. CAB International, Wallingford, UK, pp. 103-120. Dimoyiannis, D. 2012. Wet aggregate stability as affected by excess carbonate and other soil properties. Land Degradation & Development, 23: 450- 455. DOI 10.1002/ldr.1085 Fernández-Calviño, D., Garrido-Rodríguez, B., López-Periago, J. E., Paradelo, M., and Arias-Estévez, M. 2013. Spatial distribution of copper fractions in a vineyard soil. Land Degradation & Development, 24: 556- 563. DOI 10.1002/ldr.1150 García-Orenes, F., Cerdà, A., Mataix-Solera, J., Guerrero, C., Bodí, M.B., Arcenegui, V., Zornoza, R. & Sempere, J.G. 2009. Effects of agricultural management on surface soil properties and soil-water losses in eastern Spain. Soil and Tillage Research 106, 117-123. 10.1016/j.still.2009.06.002 Jacinthe, P.A., R. Lal, L.B. Owens, and D.L. Hothem. (2004) Transport of labile carbon in runoff as affected by land use and rainfall characteristics. Soil and Tillage Research 77: 111-123 Kocyigit, R., Demirci, S. 2012. Long-term changes of aggregate-associated and labile soil organic carbon and nitrogen after conversion from forest to grassland and cropland in northern Turkey. Land Degradation & Development, 23: 475- 482. DOI 10.1002/ldr.1092 Lal, R., 2003. Soil erosion and the global carbon budget. Environment International 29, 437-450 Novara, A., Gristina, L., Bodì, M.B., Cerdà, A. 2011. The impact of fire on redistribution of soil organic matter on a Mediterranean hillslope under maquia vegetation type. Land Degradation and Development, 2: 530 - 536. DOI: 10.1002/ldr.1027 Novara, A., Gristina, L., Kuzyakov, Y., Schillaci, C., Laudicina, V.A., La Mantia, T., 2013. Turnover and availability of soil organic carbon under different Mediterranean land use as estimated by 13C natural abundance. European Journal ofSoil science, 64, 466-475. DOI: 10.1111/ejss.12038 Novara, A., Gristina, L., Saladino, S., Santoro, A., Cerda, A. 2011. Soil erosion assessment on tillage and alternative soil managements in a Sicilian vineyard. Soil & Tillage Research 117:140-147. Novara, A., La Mantia, T., Barbera V., Gristina, L. 2012. Paired-site approach for studying soil organic carbon dynamics in a Mediterranean semiarid environment. Catena, 89 (1): 1-7, doi.org/10.1016/j.catena.2011.09.008 Yan-Gui, S., Xin-Rong, L., Ying-Wu, C., Zhi-Shan, Z., and Yan, L. 2013. Carbon fixaton of cyanobacterial-algal crusts after desert fixation and its implication to soil organic matter accumulation in Desert. Land Degradation & Development, 24: 342- 349. DOI 10.1002/ldr.1131

The longitudinal study of turnover and the cost of turnover in EMS

PubMed Central

Patterson, P. Daniel; Jones, Cheryl B.; Hubble, Michael W.; Carr, Matthew; Weaver, Matthew D.; Engberg, John; Castle, Nicholas

2010-01-01

Purpose Few studies have examined employee turnover and associated costs in emergency medical services (EMS). The purpose of this study was to quantify the mean annual rate of turnover, total median cost of turnover, and median cost per termination in a diverse sample of EMS agencies. Methods A convenience sample of 40 EMS agencies was followed over a 6 month period. Internet, telephone, and on-site data collection methods were used to document terminations, new hires, open positions, and costs associated with turnover. The cost associated with turnover was calculated based on a modified version of the Nursing Turnover Cost Calculation Methodology (NTCCM). The NTCCM identified direct and indirect costs through a series of questions that agency administrators answered monthly during the study period. A previously tested measure of turnover to calculate the mean annual rate of turnover was used. All calculations were weighted by the size of the EMS agency roster. The mean annual rate of turnover, total median cost of turnover, and median cost per termination were determined for 3 categories of agency staff mix: all paid staff, mix of paid and volunteer (mixed), and all-volunteer. Results The overall weighted mean annual rate of turnover was 10.7%. This rate varied slightly across agency staffing mix: (all-paid=10.2%, mixed=12.3%, all-volunteer=12.4%). Among agencies that experienced turnover (n=25), the weighted median cost of turnover was $71,613.75, which varied across agency staffing mix: (all-paid=$86,452.05, mixed=$9,766.65, and all-volunteer=$0). The weighted median cost per termination was $6,871.51 and varied across agency staffing mix: (all-paid=$7,161.38, mixed=$1,409.64, and all-volunteer=$0). Conclusions Annual rates of turnover and costs associated with turnover vary widely across types of EMS agencies. The study’s mean annual rate of turnover was lower than expected based on information appearing in the news media and EMS trade magazines. Findings provide estimates of two key workforce measures – turnover rates and costs – where previously none have existed. Local EMS directors and policymakers at all levels of government may find the results and study methodology useful towards designing and evaluating programs targeting the EMS workforce. PMID:20199235

Scale dependence in species turnover reflects variance in species occupancy.

PubMed

McGlinn, Daniel J; Hurlbert, Allen H

2012-02-01

Patterns of species turnover may reflect the processes driving community dynamics across scales. While the majority of studies on species turnover have examined pairwise comparison metrics (e.g., the average Jaccard dissimilarity), it has been proposed that the species-area relationship (SAR) also offers insight into patterns of species turnover because these two patterns may be analytically linked. However, these previous links only apply in a special case where turnover is scale invariant, and we demonstrate across three different plant communities that over 90% of the pairwise turnover values are larger than expected based on scale-invariant predictions from the SAR. Furthermore, the degree of scale dependence in turnover was negatively related to the degree of variance in the occupancy frequency distribution (OFD). These findings suggest that species turnover diverges from scale invariance, and as such pairwise turnover and the slope of the SAR are not redundant. Furthermore, models developed to explain the OFD should be linked with those developed to explain species turnover to achieve a more unified understanding of community structure.

The 18 kDa Translocator Protein (Peripheral Benzodiazepine Receptor) Expression in the Bone of Normal, Osteoprotegerin or Low Calcium Diet Treated Mice

PubMed Central

Kam, Winnie Wai-Ying; Meikle, Steven R.; Dunstan, Colin R.; Banati, Richard B.

2012-01-01

The presence of the translocator protein (TSPO), previously named as the mitochondrial or peripheral benzodiazepine receptor, in bone cells was studied in vitro and in situ using RT-qPCR, and receptor autoradiography using the selective TSPO ligand PK11195. In vitro, the TSPO is highly expressed in osteoblastic and osteoclastic cells. In situ, constitutive expression of TSPO is found in bone marrow and trabecular bone, e.g., spongiosa. Mice with a reduction of bone turnover induced by a 4-day treatment of osteoprotegerin reduces [3H]PK11195 binding in the spongiosa (320±128 Bq.mg−1, 499±106 Bq.mg−1 in saline-treated controls). In contrast, mice with an increase in bone turnover caused by a 4-day low calcium diet increases [3H]PK11195 binding in the spongiosa (615±90 Bq.mg−1). Further, our study includes technical feasibility data on [18F]fluoride microPET imaging of rodent bone with altered turnover. Despite [18F]fluoride having high uptake, the in vivo signal differences were small. Using a phantom model, we describe the spillover effect and partial volume loss that affect the quantitative microPET imaging of the small bone structures in experimental mouse models. In summary, we demonstrate the expression of TSPO in small rodent bone tissues, including osteoblasts and osteoclasts. A trend increase in TSPO expression was observed in the spongiosa from low to high bone turnover conditions. However, despite the potential utility of TSPO expression as an in vivo biomarker of bone turnover in experimental rodent models, our small animal PET imaging data using [18F]fluoride show that even under the condition of a good biological signal-to-noise ratio and high tracer uptake, the currently achievable instrument sensitivity and spatial resolution is unlikely to be sufficient to detect subtle differences in small structures, such as mouse bone. PMID:22295097

Effects of soy protein isolate and moderate exercise on bone turnover and bone mineral density in postmenopausal women

PubMed Central

Evans, Ellen M.; Racette, Susan B.; Van Pelt, Rachael E.; Peterson, Linda R.; Villareal, Dennis T.

2008-01-01

Objective The aim of this study was to assess the independent and additive effects of soy protein isolate (SPI) and moderate-intensity exercise (EX) on bone turnover and bone mineral density (BMD). Design This study used a placebo-controlled, double-blind (soy), randomized 2 (SPI vs milk protein isolate [MPI]) × 2 (EX vs no EX) design. Sixty-one postmenopausal women were randomized, and 43 (62 ± 5 y) completed the 9-month intervention (SPI, n = 10; MPI, n = 12; SPI + EX, n = 11; MPI + EX, n = 10). Serum C-terminal cross-linked telopeptides of type I collagen and serum bone-specific alkaline phosphatase were measured as markers of bone resorption and formation, respectively. BMD was measured by dual-energy x-ray absorptiometry. Results At 9 months, SPI reduced serum C-terminal cross-linked telopeptides (−13.3% ± 15.3% vs −1.5% ± 21.0%; P = 0.02) and serum bone-specific alkaline phosphatase (−4.7% ± 14.7% vs 6.5% ± 17.7%; P = 0.02) compared to milk protein isolate. EX attenuated the reduction in serum C-terminal cross-linked telopeptides (−1.9% ± 21.6% vs −12.4% ± 15.3%; P = 0.04); however, no EX effects were apparent in serum bone-specific alkaline phosphatase at 9 months (2.8% ± 16.1% vs −1.0% ± 18.3%; P = 0.28). Neither SPI nor EX affected BMD at any site; however, change in BMD was related to change in fat mass (r = 0.40, P < 0.05). Conclusions In postmenopausal women (1) SPI reduces bone turnover with no impact on BMD over 9 months; (2) moderate-intensity endurance exercise training did not favorably alter bone turnover and had no impact on BMD; and (3) there were no additive effects of soy and exercise on bone turnover or BMD. PMID:17213752

Delta-catenin/NPRAP: A new member of the glycogen synthase kinase-3beta signaling complex that promotes beta-catenin turnover in neurons.

PubMed

Bareiss, Sonja; Kim, Kwonseop; Lu, Qun

2010-08-15

Through a multiprotein complex, glycogen synthase kinase-3beta (GSK-3beta) phosphorylates and destabilizes beta-catenin, an important signaling event for neuronal growth and proper synaptic function. delta-Catenin, or NPRAP (CTNND2), is a neural enriched member of the beta-catenin superfamily and is also known to modulate neurite outgrowth and synaptic activity. In this study, we investigated the possibility that delta-catenin expression is also affected by GSK-3beta signaling and participates in the molecular complex regulating beta-catenin turnover in neurons. Immunofluorescent light microscopy revealed colocalization of delta-catenin with members of the molecular destruction complex: GSK-3beta, beta-catenin, and adenomatous polyposis coli proteins in rat primary neurons. GSK-3beta formed a complex with delta-catenin, and its inhibition resulted in increased delta-catenin and beta-catenin expression levels. LY294002 and amyloid peptide, known activators of GSK-3beta signaling, reduced delta-catenin expression levels. Furthermore, delta-catenin immunoreactivity increased and protein turnover decreased when neurons were treated with proteasome inhibitors, suggesting that the stability of delta-catenin, like that of beta-catenin, is regulated by proteasome-mediated degradation. Coimmunoprecipitation experiments showed that delta-catenin overexpression promoted GSK-3beta and beta-catenin interactions. Primary cortical neurons and PC12 cells expressing delta-catenin treated with proteasome inhibitors showed increased ubiquitinated beta-catenin forms. Consistent with the hypothesis that delta-catenin promotes the interaction of the destruction complex molecules, cycloheximide treatment of cells overexpressing delta-catenin showed enhanced beta-catenin turnover. These studies identify delta-catenin as a new member of the GSK-3beta signaling pathway and further suggest that delta-catenin is potentially involved in facilitating the interaction, ubiquitination, and subsequent turnover of beta-catenin in neuronal cells. (c) 2010 Wiley-Liss, Inc.

Acute and 3-month effects of microcrystalline hydroxyapatite, calcium citrate and calcium carbonate on serum calcium and markers of bone turnover: a randomised controlled trial in postmenopausal women.

PubMed

Bristow, Sarah M; Gamble, Greg D; Stewart, Angela; Horne, Lauren; House, Meaghan E; Aati, Opetaia; Mihov, Borislav; Horne, Anne M; Reid, Ian R

2014-11-28

Ca supplements are used for bone health; however, they have been associated with increased cardiovascular risk, which may relate to their acute effects on serum Ca concentrations. Microcrystalline hydroxyapatite (MCH) could affect serum Ca concentrations less than conventional Ca supplements, but its effects on bone turnover are unclear. In the present study, we compared the acute and 3-month effects of MCH with conventional Ca supplements on concentrations of serum Ca, phosphate, parathyroid hormone and bone turnover markers. We randomised 100 women (mean age 71 years) to 1 g/d of Ca as citrate or carbonate (citrate-carbonate), one of two MCH preparations, or a placebo. Blood was sampled for 8 h after the first dose, and after 3 months of daily supplementation. To determine whether the acute effects changed over time, eight participants assigned to the citrate dose repeated 8 h of blood sampling at 3 months. There were no differences between the citrate and carbonate groups, or between the two MCH groups, so their results were pooled. The citrate-carbonate dose increased ionised and total Ca concentrations for up to 8 h, and this was not diminished after 3 months. MCH increased ionised Ca concentrations less than the citrate-carbonate dose; however, it raised the concentrations of phosphate and the Ca-phosphate product. The citrate-carbonate and MCH doses produced comparable decreases in bone resorption (measured as serum C-telopeptide (CTX)) over 8 h and bone turnover (CTX and procollagen type-I N-terminal propeptide) at 3 months. These findings suggest that Ca preparations, in general, produce repeated sustained increases in serum Ca concentrations after ingestion of each dose and that Ca supplements with smaller effects on serum Ca concentrations may have equivalent efficacy in suppressing bone turnover.

Bacterial and enchytraeid abundance accelerate soil carbon turnover along a lowland vegetation gradient in interior Alaska

USGS Publications Warehouse

Waldrop, M.P.; Harden, Jennifer W.; Turetsky, M.R.; Petersen, D.G.; McGuire, A.D.; Briones, M.J.I.; Churchill, A.C.; Doctor, D.H.; Pruett, L.E.

2012-01-01

Boreal wetlands are characterized by a mosaic of plant communities, including forests, shrublands, grasslands, and fens, which are structured largely by changes in topography and water table position. The soil associated with these plant communities contain quantitatively and qualitatively different forms of soil organic matter (SOM) and nutrient availability that drive changes in biogeochemical cycling rates. Therefore different boreal plant communities likely contain different soil biotic communities which in turn affect rates of organic matter decomposition. We examined relationships between plant communities, microbial communities, enchytraeids, and soil C turnover in near-surface soils along a shallow topographic soil moisture and vegetation gradient in interior Alaska. We tested the hypothesis that as soil moisture increases along the gradient, surface soils would become increasingly dominated by bacteria and mesofauna and have more rapid rates of C turnover. We utilized bomb radiocarbon techniques to infer rates of C turnover and the 13C isotopic composition of SOM and respired CO2 to infer the degree of soil humification. Soil phenol oxidase and peroxidase enzyme activities were generally higher in the rich fen compared with the forest and bog birch sites. Results indicated greater C fluxes and more rapid C turnover in the surface soils of the fen sites compared to the wetland forest and shrub sites. Quantitative PCR analyses of soil bacteria and archaea, combined with enchytraeid counts, indicated that surface soils from the lowland fen ecosystems had higher abundances of these microbial and mesofaunal groups. Fungal abundance was highly variable and not significantly different among sites. Microbial data was utilized in a food web model that confirmed that rapidly cycling systems are dominated by bacterial activity and enchytraeid grazing. However, our results also suggest that oxidative enzymes play an important role in the C mineralization process in saturated systems, which has been often ignored.

Assessing the Role of Dissolved Organic Phosphate on Rates of Microbial Phosphorus Cycling

NASA Astrophysics Data System (ADS)

Gonzalez, A. C.; Popendorf, K. J.; Duhamel, S.

2016-02-01

Phosphorus (P) is an element crucial to life, and it is limiting in many parts of the ocean. In oligotrophic environments, the dissolved P pool is cycled rapidly through the activity of microbes, with turnover times of several hours or less. The overarching aim of this study was to assess the flux of P from picoplankton to the dissolved pool and the role this plays in fueling rapid P cycling. To determine if specific microbial groups are responsible for significant return of P to the dissolved pool during cell lifetime, we compared the rate of cellular P turnover (cell-Pτ, the rate of cellular P uptake divided by cellular P content) to the rate of cellular biomass turnover (cellτ). High rates of P return to the dissolved pool during cell lifetime (high cell-Pτ/cellτ) indicate significant P regeneration, fueling more rapid turnover of the dissolved P pool. We hypothesized that cell-Pτ/cellτ varies widely across picoplankton groups. One factor influencing this variation may be each microbial group's relative uptake of dissolved organic phosphorus (DOP) versus dissolved inorganic phosphorus (DIP). As extracellular hydrolysis is necessary for P incorporation from DOP, this process may return more P to the dissolved pool than DIP incorporation. This leads to the question: does a picoplankton's relative uptake of DOP (versus DIP) affect the rate at which it returns phosphorus to the dissolved pool? To address this question, we compared the rate of cellular P turnover based on uptake of DOP and uptake DIP using cultured representatives of three environmentally significant picoplankton groups: Prochlorococcus, Synechococcus, and heterotrophic bacteria. These different picoplankton groups are known to take up different ratios of DOP to DIP, and may in turn make significantly different contributions to the regeneration and cycling phosphorus. These findings have implications towards our understanding of the timeframes of biogeochemical cycling of phosphorus in the ocean.

The role of staff turnover in the implementation of evidence-based practices in mental health care.

PubMed

Woltmann, Emily M; Whitley, Rob; McHugo, Gregory J; Brunette, Mary; Torrey, William C; Coots, Laura; Lynde, David; Drake, Robert E

2008-07-01

This study examined turnover rates of teams implementing psychosocial evidence-based practices in public-sector mental health settings. It also explored the relationship between turnover and implementation outcomes in an effort to understand whether practitioner perspectives on turnover are related to implementation outcomes. Team turnover was measured for 42 implementing teams participating in a national demonstration project examining implementation of five evidence-based practices between 2002 and 2005. Regression techniques were used to analyze the effects of team turnover on penetration and fidelity. Qualitative data collected throughout the project were blended with the quantitative data to examine the significance of team turnover to those attempting to implement the practices. High team turnover was common (M+/-SD=81%+/-46%) and did not vary by practice. The 24-month turnover rate was inversely related to fidelity scores at 24 months (N=40, beta=-.005, p=.01). A negative trend was observed for penetration. Further analysis indicated that 71% of teams noted that turnover was a relevant factor in implementation. The behavioral health workforce remains in flux. High turnover most often had a negative impact on implementation, although some teams were able to use strategies to improve implementation through turnover. Implementation models must consider turbulent behavioral health workforce conditions.

Stayers, leavers, and switchers among certified nursing assistants in nursing homes: a longitudinal investigation of turnover intent, staff retention, and turnover.

PubMed

Rosen, Jules; Stiehl, Emily M; Mittal, Vikas; Leana, Carrie R

2011-10-01

Studies of certified nursing assistant (CNA) turnover in nursing homes are typically cross-sectional and include full-time and part-time workers. We conducted a longitudinal study to evaluate the job factors and work attitudes associated with just full-time staying or leaving. For those who did not stay, we assessed reasons for leaving and satisfaction following job transition. A random sample of CNAs identified through the Pennsylvania Department of Health's CNA registry, working ≥ 30 hr weekly in a nursing facility was surveyed by telephone at baseline and 1 year later. Of the 620 responding to both surveys, 532 (85.8%) remained (stayers), 52 (8.4%) switched to another facility (switchers), and 36 (5.8%) left the industry (leavers). At baseline, switchers reported higher turnover intentions and fewer benefits compared with stayers and left for new opportunities. Leavers had lower job satisfaction and emotional well-being and left for health reasons. Turnover intentions were predicted by low job satisfaction and low emotional well-being. Actual turnover was predicted only by turnover intentions and by the absence of health insurance. Pay was not a predictor of turnover intent or turnover. There are two distinct groups of CNAs contributing to turnover. Attitudinal factors, such as job satisfaction and emotional well-being, are mediated via turnover intentions to effect actual turnover. Even accounting for methodological differences, this turnover rate is lower than previous studies, which use alternative methods and include part-time workers. This study should help nursing home administrators better understand the work-related factors associated with staff turnover.

Workforce turnover at local health departments: nature, characteristics, and implications.

PubMed

Newman, Sarah J; Ye, Jiali; Leep, Carolyn J

2014-11-01

Employee turnover, defined as total separations from employment, is expensive, can result in lost capacity, and can limit local health departments' (LHDs') ability to respond to public health needs. Despite the importance of workforce capacity in public health, little is known about workforce turnover in LHDs. To examine the extent to which LHDs experience turnover and identify LHD characteristics that are associated with turnover. A cross-sectional data set of employee turnover and LHD characteristics from the 2013 National Profile of LHDs was analyzed. Descriptive statistics and bivariate analyses were conducted in 2014 on turnover rates. The effect of the following LHD characteristics on turnover rates were examined: population size, governance type, degree of urbanization, top executive experience level, expenditures per capita, and LHD budget cuts. In 2013, LHDs experienced a mean turnover rate of 9.88%; approximately one third of turnover was due to retirements. LHDs with shared state and local governance experienced a higher turnover rate than LHDs with exclusive state or local governance. LHDs that are units of state agencies had a significantly higher retirement rate than those governed by local authorities. Top executive experience level, per capita expenditures, and LHD budget cuts were also related to turnover rates. LHDs experienced a lower overall turnover rate than state health departments in 2011 and lower than all local and state government agencies in 2012. Strengthening leadership skills of new top executives and ensuring adequate funding may reduce turnover in LHDs. Copyright © 2014 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Microbial hotspots and hot moments in soil

NASA Astrophysics Data System (ADS)

Kuzyakov, Yakov; Blagodatskaya, Evgenia

2015-04-01

Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes within nano- to macroscales. The spatial and temporal heterogeneity of input of labile organics by plants creates microbial hotspots over short periods of time - the hot moments. We define microbial hotspots as small soil volumes with much faster process rates and much more intensive interactions compared to the average soil conditions. Such hotspots are found in the rhizosphere, detritusphere, biopores (including drilosphere) and on aggregate surfaces, but hotspots are frequently of mixed origin. Hot moments are short-term events or sequences of events inducing accelerated process rates as compared to the averaged rates. Thus, hotspots and hot moments are defined by dynamic characteristics, i.e. by process rates. For this hotspot concept we extensively reviewed and examined the localization and size of hotspots, spatial distribution and visualization approaches, transport of labile C to and from hotspots, lifetime and process intensities, with a special focus on process rates and microbial activities. The fraction of active microorganisms in hotspots is 2-20 times higher than in the bulk soil, and their specific activities (i.e. respiration, microbial growth, mineralization potential, enzyme activities, RNA/DNA ratio) may also be much higher. The duration of hot moments in the rhizosphere is limited and is controlled by the length of the input of labile organics. It can last a few hours up to a few days. In the detritusphere, however, the duration of hot moments is regulated by the output - by decomposition rates of litter - and lasts for weeks and months. Hot moments induce succession in microbial communities and intense intra- and interspecific competition affecting C use efficiency, microbial growth and turnover. The faster turnover and lower C use efficiency in hotspots counterbalances the high C inputs, leading to the absence of strong increases in C stocks. Consequently, the intensification of fluxes is much stronger than the increase of pools. Maintenance of stoichiometric ratios by accelerated microbial growth in hotspots requires additional nutrients (e.g. N and P), causing their microbial mining from soil organic matter, i.e. priming effects. Consequently, priming effects are localized in microbial hotspots and are consequences of hot moments. Finally, we estimated the contribution of the hotspots to the whole soil profile and suggested that, irrespective of their volume, the hotspots are mainly responsible for the ecologically relevant processes in soil.

Revisiting the impact of job satisfaction and organizational commitment on nurse turnover intention: an individual differences analysis.

PubMed

De Gieter, Sara; Hofmans, Joeri; Pepermans, Roland

2011-12-01

Nurse turnover is an important contributing factor to the worldwide nursing shortage. Many studies have examined the antecedents of nurse turnover to gain a better understanding of the problem and help hospitals reduce their turnover rates. However, an important shortcoming of this research stream is its exclusive focus on explaining turnover behavior of the "average nurse", thereby disregarding individual differences between nurses and groups of nurses. To examine individual differences in the relationships between two crucial turnover antecedents - job satisfaction and organizational commitment - and nurse turnover intention. A sample of 287 nurses working for a variety of Belgian hospitals participated in the study. A survey method was used to collect quantitative data, which were analyzed through standard multiple linear regression, mixture regression models and t-tests. In the total sample of hospital nurses, both job satisfaction and organizational commitment significantly predicted nurse turnover intention. However, subsequent individual differences analyses revealed the existence of two subgroups of nurses. In the satisfaction focused group, only job satisfaction was found to predict nurse turnover intention, whereas in the satisfaction and commitment focused group both job satisfaction and organizational commitment were related to turnover intention. Furthermore, nurses in the latter group displayed stronger turnover intention, were significantly younger and had less job tenure and organizational tenure than nurses in the satisfaction focused group. The debate on the antecedents of nurse turnover still continues, as the existing models fail to fully grasp nurse turnover. The present study identifies individual differences in nurse turnover antecedents among groups of nurses as a possible reason for the absence of one comprehensive turnover model that holds for the general nursing population. Further studies are needed in order to capture the total impact of the underlying individual differences in nurse turnover antecedents. 2011 Elsevier Ltd. All rights reserved.

Compressive Strength and Water Absorption of Pervious Concrete that Using the Fragments of Ceramics and Roof Tiles

NASA Astrophysics Data System (ADS)

Prahara, E.; Meilani

2014-03-01

Pervious concrete was introduced in America in 2003, popularized by Dan Brown and used as a rigid pavement in the open parking lot. Rigid pavement using pervious concrete can absorb water in the surface to go straight through the concrete to the ground below.This water flow is one of the benefit of using the pervious concrete. Using of wastes such as broken roof and ceramics tiles are not commonly used in Indonesia. Utilization these kind of wastes is predicted lower the compressive strength of pervious concrete as they are used as a substitute for coarse aggregate.In this research, pervious concrete is made using a mixture of the fragment of ceramics and roof tiles.This research using broken ceramics and roof tiles with a grain size that loose from 38 mm sieve, retained on 19 mm sieve and the coarse aggregate from crushed stone that loose 12.5 mm sieve, retained on 9.5 mm sieve. The water cement ratio is 0.3 and to assist the mixing process, the addition of addictive in pervious concrete is used.The size of coarse aggregate used in the mixture affects the strength of pervious concrete. The larger the size of aggregate, the obtained compressive strength becomes smaller. It also affects the density of pervious concrete. The using of mixture of ceramics and roof tiles only reduce 2 MPa of pervious concrete compressive strength so this mixture can be used as a substitute for coarse aggregate with a maximum portion of 30 %. The high porosity of the specimens causes the reduction of pervious concrete density that affect the compressive strength. This high level of porosity can be seen from the high level of water absorption that exceed the required limit of water infiltration.

Does Aggregated Returns Disclosure Increase Portfolio Risk Taking?

PubMed

Beshears, John; Choi, James J; Laibson, David; Madrian, Brigitte C

2017-06-01

Many experiments have found that participants take more investment risk if they see returns less frequently, see portfolio-level returns (rather than each individual asset's returns), or see long-horizon (rather than one-year) historical return distributions. In contrast, we find that such information aggregation treatments do not affect total equity investment when we make the investment environment more realistic than in prior experiments. Previously documented aggregation effects are not robust to changes in the risky asset's return distribution or the introduction of a multi-day delay between portfolio choice and return realizations.

COSMIC DUST AGGREGATION WITH STOCHASTIC CHARGING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthews, Lorin S.; Hyde, Truell W.; Shotorban, Babak, E-mail: Lorin_Matthews@baylor.edu

2013-10-20

The coagulation of cosmic dust grains is a fundamental process which takes place in astrophysical environments, such as presolar nebulae and circumstellar and protoplanetary disks. Cosmic dust grains can become charged through interaction with their plasma environment or other processes, and the resultant electrostatic force between dust grains can strongly affect their coagulation rate. Since ions and electrons are collected on the surface of the dust grain at random time intervals, the electrical charge of a dust grain experiences stochastic fluctuations. In this study, a set of stochastic differential equations is developed to model these fluctuations over the surface ofmore » an irregularly shaped aggregate. Then, employing the data produced, the influence of the charge fluctuations on the coagulation process and the physical characteristics of the aggregates formed is examined. It is shown that dust with small charges (due to the small size of the dust grains or a tenuous plasma environment) is affected most strongly.« less

Controlling Photoconductivity in PBI Films by Supramolecular Assembly.

PubMed

Draper, Emily R; Archibald, Lewis J; Nolan, Michael C; Schweins, Ralf; Zwijnenburg, Martijn A; Sproules, Stephen; Adams, Dave J

2018-03-15

Perylene bisimides (PBIs) self-assemble in solution. The solubility of the PBIs is commonly changed through the choice of substituents at the imide positions. It is generally assumed this substitution does not affect the electronic properties of the PBI, and that the properties of the self-assembled aggregate are essentially that of the isolated molecule. However, substituents do affect the self-assembly, resulting in potentially different packing in the formed aggregates. Here, we show that the photoconductivity of films formed from a library of substituted PBIs varies strongly with the substituent and demonstrate that this is due to the different ways in which they pack. Our results open the possibility for tuning the optoelectronic properties of self-assembled PBIs by controlling the aggregate structure through careful choice of substituent, as demonstrated by us here optimising the photoconductivity of PBI films in this way. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Controlling Photoconductivity in PBI Films by Supramolecular Assembly

PubMed Central

Archibald, Lewis J.; Nolan, Michael C.; Schweins, Ralf; Zwijnenburg, Martijn A.; Sproules, Stephen

2018-01-01

Abstract Perylene bisimides (PBIs) self‐assemble in solution. The solubility of the PBIs is commonly changed through the choice of substituents at the imide positions. It is generally assumed this substitution does not affect the electronic properties of the PBI, and that the properties of the self‐assembled aggregate are essentially that of the isolated molecule. However, substituents do affect the self‐assembly, resulting in potentially different packing in the formed aggregates. Here, we show that the photoconductivity of films formed from a library of substituted PBIs varies strongly with the substituent and demonstrate that this is due to the different ways in which they pack. Our results open the possibility for tuning the optoelectronic properties of self‐assembled PBIs by controlling the aggregate structure through careful choice of substituent, as demonstrated by us here optimising the photoconductivity of PBI films in this way. PMID:29405458

Effects of Grape Xylem Sap and Cell-Wall Constituents on In Vitro Growth, Biofilm Formation and Cellular Aggregation of Xylella fastidiosa

USDA-ARS?s Scientific Manuscript database

Purified cell-wall constituents or grape xylem sap added to media affected in vitro growth, biofilm formation, cell aggregation and gene expression of Xylella fastidiosa. Media containing xylem sap from Pierce’s disease (PD)-susceptible plants provided better support for bacterial growth and biofil...

12 CFR 723.17 - Are there any exceptions to the aggregate loan limit?

Code of Federal Regulations, 2010 CFR

2010-01-01

... AFFECTING CREDIT UNIONS MEMBER BUSINESS LOANS § 723.17 Are there any exceptions to the aggregate loan limit.... Loans that are excepted from the definition of member business loans are not counted for the purpose of... for the purpose of making member business loans and can provide documentary evidence (such evidence...

Employer model of workplace impacts of anti-TNF therapy for rheumatoid arthritis.

PubMed

Birnbaum, Howard; Pike, Crystal; Kaufman, Rebecca; Cifaldi, Mary

2009-10-01

Rheumatoid arthritis (RA) greatly affects patients' abilities to perform work, which can translate into substantial employer costs. We developed a customizable model that allows employers to calculate workplace impacts of RA therapies in employees with RA. Costs of medical leave (absenteeism)/disability, reduced productivity, job turnover, and work-equipment adaptations for employees with RA were calculated. Costs of the tumor necrosis factor antagonist adalimumab were compared with those of other RA treatments. Default parameters were based on literature, clinical trials, government sources, and employers' data. Annual per-employee workplace cost was $9071 for adalimumab versus $16,335 for other RA therapies. Costs included reduced productivity (57%), absenteeism/disability (21%), and job turnover (21%). RA imposes a large financial burden on employers, predominantly owing to lost productivity. When compared with other RA therapies, adalimumab substantially reduced employers' costs.

Molluscan extinction patterns across the Cenomanian-Turonian stage boundary in the western interior of the United States

USGS Publications Warehouse

Elder, W.P.

1989-01-01

High-resolution stratigraphic analysis of 18 sections spanning the Cenomanian-Turonian Stage boundary in the western interior of the United States has allowed determination of the magnitude and pattern of molluscan extinction and disruption. Composite range data from all sections show that the faunal turnover across the stage boundary occurs in a series of narrow stratigraphic zones, defined by multiple first and last occurrences, separated by intervals displaying little or no taxonomic turnover. Two of the apparent extinction steps (bottom and top of the Neocardioceras juddii Zone) may be intercontinentally developed. The additional steps apparently reflect cyclic changes in water mass and substrate characteristics in the western interior basin produced in response to orbital forcing of climate. The most affected mollusks were those having intercontinental distributions. -Author

Effects of Phytoplankton Growth Phase on Delayed Settling Behavior of Marine Snow Aggregates at Sharp Density Transitions

NASA Astrophysics Data System (ADS)

Proctor, K. W.; Montgomery, Q. W.; Prairie, J. C.

2016-02-01

Marine snow aggregates play a fundamental role in the marine carbon cycle. Since marine snow aggregates are larger and thus sink faster than individual phytoplankton, aggregates often dominate carbon flux. Previous studies have shown that marine snow aggregates will significantly decrease their settling velocity when passing through sharp density transitions within the ocean, a phenomenon defined as delayed settling. Given the importance of aggregate settling to carbon export, these small-scale changes in aggregate settling dynamics may have significant impacts on the efficiency of the biological pump. However, there is still a lack of knowledge about how different physical properties of aggregates can affect this delayed settling. In this study, we investigated the effect of phytoplankton growth phase on delayed settling behavior. Using phytoplankton cultures stopped at four different growth phases, we formed marine snow aggregates in the laboratory in rotating cylindrical tanks. We then observed individual aggregates as they settled through a stratified tank. We will present data which illustrates that aggregates experience greatly reduced settling rates when passing through sharp density gradients and that the growth phase of the phytoplankton used to form these aggregates has a significant effect on this delayed settling behavior. A thorough understanding of the impact of phytoplankton growth phase on the delayed settling behavior of marine snow will offer insight into the way phytoplankton growth phase may influence the efficiency of the biological pump, carbon flux, and the carbon cycle as a whole.

Aggregation of recombinant human botulinum protein antigen serotype C in varying solution conditions: implications of conformational stability for aggregation kinetics.

PubMed

Bai, Shujun; Manning, Mark Cornell; Randolph, Theodore W; Carpenter, John F

2011-03-01

Solution conditions greatly affect the aggregation rate of a protein. Elucidating these influences provides insight into the critical factors governing aggregation. In this study, recombinant human botulinum protein antigen serotype C [rBoNTC (H(c))] was employed as a model protein. rBoNTC (H(c)) aggregated irreversibly during incubation at 42°C. The aggregation rate was studied as a function of solution conditions, including varying the pH from 3.5 to 8.0 and with or without 150 mM NaCl, 7.5% (w/v) trehalose, and 0.5 M urea. Some solution conditions retarded rBoNTC (H(c)) aggregation, whereas others accelerated aggregation, particularly acidic pH and addition of NaCl or urea. To better understand the mechanism by which these solution conditions influenced aggregation rates, the structure of rBoNTC (H(c)) was characterized using circular dichroism, fluorescence, and ultraviolet absorbance spectroscopies. Conformational stability was assessed from equilibrium urea-induced unfolding studies and by using differential scanning calorimetry (DSC). The activation energy of the aggregation reaction (E(a)) was estimated from an analysis of the heating-rate dependence of the thermal transition observed during DSC heating scans. Overall, for rBoNTC (H(c)), an inverse correlation was found between conformational stability and aggregation rate, as well as between the kinetic barrier to unfolding (i.e., E(a)) and aggregation rate. Copyright © 2010 Wiley-Liss, Inc.

Body size, growth and life span: implications for the polewards range shift of Octopus tetricus in south-eastern Australia.

PubMed

Ramos, Jorge E; Pecl, Gretta T; Moltschaniwskyj, Natalie A; Strugnell, Jan M; León, Rafael I; Semmens, Jayson M

2014-01-01

Understanding the response of any species to climate change can be challenging. However, in short-lived species the faster turnover of generations may facilitate the examination of responses associated with longer-term environmental change. Octopus tetricus, a commercially important species, has undergone a recent polewards range shift in the coastal waters of south-eastern Australia, thought to be associated with the southerly extension of the warm East Australian Current. At the cooler temperatures of a polewards distribution limit, growth of a species could be slower, potentially leading to a bigger body size and resulting in a slower population turnover, affecting population viability at the extreme of the distribution. Growth rates, body size, and life span of O. tetricus were examined at the leading edge of a polewards range shift in Tasmanian waters (40°S and 147°E) throughout 2011. Octopus tetricus had a relatively small body size and short lifespan of approximately 11 months that, despite cooler temperatures, would allow a high rate of population turnover and may facilitate the population increase necessary for successful establishment in the new extended area of the range. Temperature, food availability and gender appear to influence growth rate. Individuals that hatched during cooler and more productive conditions, but grew during warming conditions, exhibited faster growth rates and reached smaller body sizes than individuals that hatched into warmer waters but grew during cooling conditions. This study suggests that fast growth, small body size and associated rapid population turnover may facilitate the range shift of O. tetricus into Tasmanian waters.

Body Size, Growth and Life Span: Implications for the Polewards Range Shift of Octopus tetricus in South-Eastern Australia

PubMed Central

Ramos, Jorge E.; Pecl, Gretta T.; Moltschaniwskyj, Natalie A.; Strugnell, Jan M.; León, Rafael I.; Semmens, Jayson M.

2014-01-01

Understanding the response of any species to climate change can be challenging. However, in short-lived species the faster turnover of generations may facilitate the examination of responses associated with longer-term environmental change. Octopus tetricus, a commercially important species, has undergone a recent polewards range shift in the coastal waters of south-eastern Australia, thought to be associated with the southerly extension of the warm East Australian Current. At the cooler temperatures of a polewards distribution limit, growth of a species could be slower, potentially leading to a bigger body size and resulting in a slower population turnover, affecting population viability at the extreme of the distribution. Growth rates, body size, and life span of O. tetricus were examined at the leading edge of a polewards range shift in Tasmanian waters (40°S and 147°E) throughout 2011. Octopus tetricus had a relatively small body size and short lifespan of approximately 11 months that, despite cooler temperatures, would allow a high rate of population turnover and may facilitate the population increase necessary for successful establishment in the new extended area of the range. Temperature, food availability and gender appear to influence growth rate. Individuals that hatched during cooler and more productive conditions, but grew during warming conditions, exhibited faster growth rates and reached smaller body sizes than individuals that hatched into warmer waters but grew during cooling conditions. This study suggests that fast growth, small body size and associated rapid population turnover may facilitate the range shift of O. tetricus into Tasmanian waters. PMID:25090250