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.

Horizontal and vertical species turnover in tropical birds in habitats with differing land use.

PubMed

Sreekar, Rachakonda; Corlett, Richard T; Dayananda, Salindra; Goodale, Uromi Manage; Kilpatrick, Adam; Kotagama, Sarath W; Koh, Lian Pin; Goodale, Eben

2017-05-01

Large tracts of tropical rainforests are being converted into intensive agricultural lands. Such anthropogenic disturbances are known to reduce species turnover across horizontal distances. But it is not known if they can also reduce species turnover across vertical distances (elevation), which have steeper climatic differences. We measured turnover in birds across horizontal and vertical sampling transects in three land-use types of Sri Lanka: protected forest, reserve buffer and intensive-agriculture, from 90 to 2100 m a.s.l. Bird turnover rates across horizontal distances were similar across all habitats, and much less than vertical turnover rates. Vertical turnover rates were not similar across habitats. Forest had higher turnover rates than the other two habitats for all bird species. Buffer and intensive-agriculture had similar turnover rates, even though buffer habitats were situated at the forest edge. Therefore, our results demonstrate the crucial importance of conserving primary forest across the full elevational range available. © 2017 The Author(s).

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

Understanding the Uncertainties in Consequences of Climate Change for the United States Power Sector Infrastructure when Considering a Realistic Mitigation Pace and Adaptation Needs.

NASA Astrophysics Data System (ADS)

Anderson, N. J.; Whiteford, E. J.; Jones, V.; Fritz, S. C.; Yang, H.; Appleby, P.; Bindler, R.

2014-12-01

In order to overcome the potential damages associated with climate change, a massive reduction in greenhouse gas emissions is necessary. Achieving these levels of emissions reductions will require dramatic changes in the U.S. electricity generating infrastructure: almost all of the fossil-generation fleet will need to be replaced with low-carbon sources and society would have to maintain a high build rate of new capacity for decades. Because the build rate of new electricity generating capacity may be limited, the timing of regulation is critical—the longer the U.S. waits to start reducing emissions, the faster the turnover in the electricity sector must occur in order to meet the same target. We investigate the relationship between climate policy timing and infrastructure turnover in the electricity sector. How long can we wait before constraints on infrastructure turnover in the electricity sector make achieving our climate goals impossible? We show that delaying climate change policy increases average construction rates by 25% to 85% and increases maximum construction rates by 50% to 300%. We also show that delaying climate policy has little effect on the age of retired plants or the stranded costs associated with premature retirement. We show that as we delay policy action, some goals won't be possible for attain. For example, unless we enable emissions reductions today, reducing cumulative emissions between now and 2040 by 50% when compared to a no-policy scenario is not possible.

A comparative review of nurse turnover rates and costs across countries.

PubMed

Duffield, Christine M; Roche, Michael A; Homer, Caroline; Buchan, James; Dimitrelis, Sofia

2014-12-01

To compare nurse turnover rates and costs from four studies in four countries (US, Canada, Australia, New Zealand) that have used the same costing methodology; the original Nursing Turnover Cost Calculation Methodology. Measuring and comparing the costs and rates of turnover is difficult because of differences in definitions and methodologies. Comparative review. Searches were carried out within CINAHL, Business Source Complete and Medline for studies that used the original Nursing Turnover Cost Calculation Methodology and reported on both costs and rates of nurse turnover, published from 2014 and prior. A comparative review of turnover data was conducted using four studies that employed the original Nursing Turnover Cost Calculation Methodology. Costing data items were converted to percentages, while total turnover costs were converted to US 2014 dollars and adjusted according to inflation rates, to permit cross-country comparisons. Despite using the same methodology, Australia reported significantly higher turnover costs ($48,790) due to higher termination (~50% of indirect costs) and temporary replacement costs (~90% of direct costs). Costs were almost 50% lower in the US ($20,561), Canada ($26,652) and New Zealand ($23,711). Turnover rates also varied significantly across countries with the highest rate reported in New Zealand (44·3%) followed by the US (26·8%), Canada (19·9%) and Australia (15·1%). A significant proportion of turnover costs are attributed to temporary replacement, highlighting the importance of nurse retention. The authors suggest a minimum dataset is also required to eliminate potential variability across countries, states, hospitals and departments. © 2014 John Wiley & Sons Ltd.

Impact and determinants of nurse turnover: a pan-Canadian study.

PubMed

O'Brien-Pallas, Linda; Murphy, Gail Tomblin; Shamian, Judith; Li, Xiaoqiang; Hayes, Laureen J

2010-11-01

As part of a large study of nursing turnover in Canadian hospitals, the present study focuses on the impact and key determinants of nurse turnover and implications for management strategies in nursing units. Nursing turnover is an issue of ever-increasing priority as work-related stress and job dissatisfaction are influencing nurses' intention to leave their positions. Data sources included the nurse survey, unit managers, medical records and human resources databases. A broad sample of hospitals was represented with nine different types of nursing units included. Nurses turnover is a major problem in Canadian hospitals with a mean turnover rate of 19.9%. Higher levels of role ambiguity and role conflict were associated with higher turnover rates. Increased role conflict and higher turnover rates were associated with deteriorated mental health. Higher turnover rates were associated with lower job satisfaction. Higher turnover rate and higher level of role ambiguity were associated with an increased likelihood of medical error. Managing turnover within nursing units is critical to high-quality patient care. A supportive practice setting in which role responsibilities are understood by all members of the caregiver team would promote nurse retention. Stable nurse staffing and adequate managerial support are essential to promote job satisfaction and high-quality patient care. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd.

Primary care provider turnover and quality in managed care organizations.

PubMed

Plomondon, Mary E; Magid, David J; Steiner, John F; MaWhinney, Samantha; Gifford, Blair D; Shih, Sarah C; Grunwald, Gary K; Rumsfeld, John S

2007-08-01

To examine the association between primary care provider turnover in managed care organizations and measures of member satisfaction and preventive care. Retrospective cohort study of a national sample of 615 managed care organizations that reported HEDIS data to the National Committee for Quality Assurance from 1999 through 2001. Multivariable hierarchical regression modeling was used to evaluate the association between health plan primary care provider turnover rate and member satisfaction and preventive care measures, including childhood immunization, well-child visits, cholesterol, diabetes management, and breast and cervical cancer screening, adjusting for patient and organizational characteristics, time, and repeated measures. The median primary care provider turnover rate was 7.1% (range, 0%-53.3%). After adjustment for plan characteristics, health plans with higher primary care provider turnover rates had significantly lower measures of member satisfaction, including overall rating of healthcare (P < .01). A 10% higher primary care provider turnover rate was associated with 0.9% fewer members rating high overall satisfaction with healthcare. Health plans with higher provider turnover rates also had lower rates of preventive care, including childhood immunization (P = .045), well-child visits (P = .002), cholesterol screening after cardiac event (P = .042), and cervical cancer screening (P = .024). For example, a 10% higher primary care provider turnover was associated with a 2.7% lower rate of child-members receiving well-child visits in the first 15 months of life. Primary care provider turnover is associated with several measures of care quality, including aspects of member satisfaction and preventive care. Future studies should evaluate whether interventions to reduce primary care provider turnover can improve quality of care and patient outcomes.

Plasma Protein Turnover Rates in Rats Using Stable Isotope Labeling, Global Proteomics, and Activity-Based Protein Profiling

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

Smith, Jordan Ned; Tyrrell, Kimberly J.; Hansen, Joshua R.

Protein turnover is important for general health on cellular and organism scales providing a strategy to replace old, damaged, or dysfunctional proteins. Protein turnover also informs of biomarker kinetics, as a better understanding of synthesis and degradation of proteins increases the clinical utility of biomarkers. Here, turnover rates of plasma proteins in rats were measured in vivo using a pulse-chase stable isotope labeling experiment. During the pulse, rats (n=5) were fed 13C6-labeled lysine (“heavy”) feed for 23 days to label proteins. During the chase, feed was changed to an unlabeled equivalent feed (“light”), and blood was repeatedly sampled from ratsmore » over 10 time points for 28 days. Plasma samples were digested with trypsin, and analyzed with liquid chromatography-tandem mass spectrometry (LC-MS/MS). MaxQuant was used to identify peptides and proteins, and quantify heavy:light lysine ratios. A system of ordinary differential equations was used to calculate protein turnover rates. Using this approach, 273 proteins were identified, and turnover rates were quantified for 157 plasma proteins with half-lives ranging 0.3-103 days. For the ~70 most abundant proteins, variability in turnover rates among rats was low (median coefficient of variation: 0.09). Activity-based protein profiling was applied to pooled plasma samples to enrich serine hydrolases using a fluorophosphonate (FP2) activity-based probe. This enrichment resulted in turnover rates for an additional 17 proteins. This study is the first to measure global plasma protein turnover rates in rats in vivo, measure variability of protein turnover rates in any animal model, and utilize activity-based protein profiling for enhancing measurements of targeted, low-abundant proteins, such as those commonly used as biomarkers. Measured protein turnover rates will be important for understanding of the role of protein turnover in cellular and organism health as well as increasing the utility of protein biomarkers through better understanding of processes governing biomarker kinetics.« less

Mentor program boosts new nurses' satisfaction and lowers turnover rate.

PubMed

Fox, Kathy C

2010-07-01

In 2004, the turnover rate among first-year registered nurses (RNs) at St. Francis Hospital and Health Centers had mushroomed to 31%. Based on research, in 2006, the hospital embarked on a journey to implement an RN mentor program to improve satisfaction and reduce turnover. A pilot program was initiated, including 12 RN mentors and 12 RN protégés from select nursing units. The results showed a 0% turnover rate during the 1-year pilot program. Based on these findings, the mentor program was expanded to include RNs working in inpatient nursing units and surgery and emergency departments. Each year, the RN turnover rate has decreased. In 2009, the turnover rate was 10.3%. Because of the success of the program, it has been expanded in scope to include other professionals experiencing high turnover in targeted departments, including radiological technicians, respiratory therapists, pharmacists, and physical therapists.

Impact of euthanasia rates, euthanasia practices, and human resource practices on employee turnover in animal shelters.

PubMed

Rogelberg, Steven G; Reeve, Charlie L; Spitzmüller, Christiane; DiGiacomo, Natalie; Clark, Olga L; Teeter, Lisa; Walker, Alan G; Starling, Paula G; Carter, Nathan T

2007-03-01

To examine the effects of euthanasia rates, euthanasia practices, and human resource practices on the turnover rate among employees with euthanasia responsibilities at animal shelters. Cross-sectional original study. 36 shelters across the United States that employed at least 5 full-time employees and performed euthanasia on site. By mail, 1 survey was sent to each shelter. Surveys were completed by a senior member of management and were returned by mail. Questions assessed characteristics (eg, euthanasia rates) and practices of the animal shelter, along with employee turnover rates. By use of correlation coefficients and stepwise regression analyses, key predictors of turnover rates among employees with euthanasia responsibilities were investigated. Employee turnover rates were positively related to euthanasia rate. Practices that were associated with decreased turnover rates included provision of a designated euthanasia room, exclusion of other live animals from vicinity during euthanasia, and removal of euthanized animals from a room prior to entry of another animal to be euthanized. Making decisions regarding euthanasia of animals on the basis of factors other than behavior and health reasons was related to increased personnel turnover. With regard to human resources practices, shelters that used a systematic personnel selection procedure (eg, standardized testing) had comparatively lower employee turnover. Data obtained may suggest several specific avenues that can be pursued to mitigate turnover among employees with euthanasia responsibilities at animal shelters and animal control or veterinary medical organizations.

Soil clay content controls the turnover of slow soil carbon across Chinese cropland

NASA Astrophysics Data System (ADS)

Feng, W.; Jiang, J.; Li, J.

2017-12-01

Improving the prediction of changes in global soil organic carbon (SOC) lies in accurate estimate of C inputs to soils and SOC turnover time. Since C inputs to soils in cropland can be estimated due to well documented data of crop yields, SOC turnover rate becomes critical for accurate prediction of changes in SOC. The laboratory incubation is widely used but cannot well represent the turnover of slow soil C that accounts for the majority of total SOC, while the long-term observation of temporal changes in SOC stock offers an opportunity to estimate the turnover of slow soil C. Using time series data of SOC stock of twenty long-term agricultural trials that have initiated since 1990 in China, we estimated SOC turnover rates based on changes in soil C pool size and aimed to identify the dominant controls on SOC turnover rate across Chinese cropland. We used the two-pool first-order kinetic soil C model and the inverse modeling with Markov chain the Monte Carlo algorithm, and estimated humification coefficient (h) of C inputs to soils, turnover rates of fast and slow soil C pools, and the transfer coefficient between these two soil C pools. The preliminary results show that the turnover rate of slow soil C is positively correlated with climate (i.e. mean annual temperature and precipitation) but negatively correlated with the clay content, demonstrating that the clay content is important in regulating SOC turnover rates. The ratio of humification coefficient to C turnover rate (h/k) that indicates soil C sequestration efficiency, is negatively correlated with climate and positively correlated with the clay content. In addition, the quantity of C inputs is correlated with h/k and the turnover rate of slow soil C, suggesting that the quantity of C inputs plays an important role in mediating C sequestration efficiency. Further results will inform us the main controls on SOC turnover in Chinese cropland. Keywords: SOC; turnover; long-term trial; temporal change; clay content; inverse modeling

Explaining the Gap in Charter and Traditional Public School Teacher Turnover Rates

ERIC Educational Resources Information Center

Stuit, David A.; Smith, Thomas M.

2012-01-01

This study uses national survey data to examine why charter school teachers are more likely to turnover than their traditional public school counterparts. We test whether the turnover gap is explained by different distributions of factors that are empirically and theoretically linked to turnover risk. We find that the turnover rate of charter…

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.

How the Timing of Climate Change Policy Affects Infrastructure Turnover in the Electricity Sector: Engineering, Economic and Policy Considerations

NASA Astrophysics Data System (ADS)

Izard, Catherine Finlay

The electricity sector is responsible for producing 35% of US greenhouse gas (GHG) emissions. Estimates suggest that ideally, the electricity sector would be responsible for approximately 85% of emissions abatement associated with climate polices such as America's Clean Energy and Security Act (ACES). This is equivalent to ˜50% cumulative emissions reductions below projected cumulative business-as-usual (BAU) emissions. Achieving these levels of emissions reductions will require dramatic changes in the US electricity generating infrastructure: almost all of the fossil-generation fleet will need to be replaced with low-carbon sources and society is likely to have to maintain a high build rate of new capacity for decades. Unfortunately, the inertia in the electricity sector means that there may be physical constraints to the rate at which new electricity generating capacity can be built. Because the build rate of new electricity generating capacity may be limited, the timing of regulation is critical---the longer the U.S. waits to start reducing GHG emissions, the faster the turnover in the electricity sector must occur in order to meet the same target. There is a real, and thus far unexplored, possibility that the U.S. could delay climate change policy implementation for long enough that it becomes infeasible to attain the necessary rate of turnover in the electricity sector. This dissertation investigates the relationship between climate policy timing and infrastructure turnover in the electricity sector. The goal of the dissertation is to answer the question: How long can we wait before constraints on infrastructure turnover in the electricity sector make achieving our climate goals impossible? Using the Infrastructure Flow Assessment Model, which was developed in this work, this dissertation shows that delaying climate change policy increases average retirements rates by 200-400%, increases average construction rates by 25-85% and increases maximum construction rates by 50-300%. It also shows that delaying climate policy has little effect on the age of retired plants or the stranded costs associated with premature retirement. In order for the electricity sector to reduce emissions to a level required by ACES while limiting construction rates to within achievable levels, it is necessary to start immediately. Delaying the process of decarbonization means that more abatement will be necessary from other sectors or geoengineering. By not starting emissions abatement early, therefore, the US forfeits its most accessible abatement potential and increases the challenge of climate change mitigation unnecessarily.

A Ministudy of employee turnover in US hospitals.

PubMed

Collins, Sandra K; McKinnies, Richard C; Matthews, Eric P; Collins, Kevin S

2015-01-01

A ministudy was conducted to collect self-reported employee turnover rates in US hospitals. The results indicate many hospitals are struggling with high employee turnover rates. Widespread variances in ratings were observed across hospitals, which may be due to lack of consistency in how they each calculate their employee turnover. This makes benchmarking for the purposes of performance improvement challenging.

Forest turnover rates follow global and regional patterns of productivity

USGS Publications Warehouse

Stephenson, N.L.; van Mantgem, P.J.

2005-01-01

Using a global database, we found that forest turnover rates (the average of tree mortality and recruitment rates) parallel broad-scale patterns of net primary productivity. First, forest turnover was higher in tropical than in temperate forests. Second, as recently demonstrated by others, Amazonian forest turnover was higher on fertile than infertile soils. Third, within temperate latitudes, turnover was highest in angiosperm forests, intermediate in mixed forests, and lowest in gymnosperm forests. Finally, within a single forest physiognomic type, turnover declined sharply with elevation (hence with temperature). These patterns of turnover in populations of trees are broadly similar to the patterns of turnover in populations of plant organs (leaves and roots) found in other studies. Our findings suggest a link between forest mass balance and the population dynamics of trees, and have implications for understanding and predicting the effects of environmental changes on forest structure and terrestrial carbon dynamics. ??2005 Blackwell Publishing Ltd/CNRS.

Nurse turnover in the Kingdom of Saudi Arabia: An integrative review.

PubMed

Falatah, Rawaih; Salem, Olfat A

2018-04-06

To appraise and synthesise existing literature on nurse turnover in the Saudi Arabian context. Saudi Arabia is notably one of the nations with a health care system that is bombarded by high rates of turnover and turnover intention. Moreover, rapid population growth and the expansion of the health care system increase the demand on registered nurses in the kingdom. Eleven primary sources were reviewed using Whittemore and Knafl's (Journal of Advanced Nursing, 2005; 52, 546-553) integrative review method. There is variation in the reported turnover rates across the studies. The identified determinants of nurse turnover in the Saudi Arabian context included nurses' demographics, satisfaction, leadership and management, and job-related factors. There is a need for more studies that focus on the cost and outcome of nurse turnover and turnover intention in the Saudi Arabian context. The review highlights the alarming rates of nurse turnover and its determinants in Saudi Arabia. Nurse managers in Saudi Arabia should consider this information, as they make daily assignments. © 2018 John Wiley & Sons Ltd.

Dynamic structure of stock communities: a comparative study between stock returns and turnover rates

NASA Astrophysics Data System (ADS)

Su, Li-Ling; Jiang, Xiong-Fei; Li, Sai-Ping; Zhong, Li-Xin; Ren, Fei

2017-07-01

The detection of community structure in stock market is of theoretical and practical significance for the study of financial dynamics and portfolio risk estimation. We here study the community structures in Chinese stock markets from the aspects of both price returns and turnover rates, by using a combination of the PMFG and infomap methods based on a distance matrix. An empirical study using the overall data set shows that for both returns and turnover rates the largest communities are composed of specific industrial or conceptional sectors and the correlation inside a sector is generally larger than the correlation between different sectors. However, the community structure for turnover rates is more complex than that for returns, which indicates that the interactions between stocks revealed by turnover rates may contain more information. This conclusion is further confirmed by the analysis of the changes in the dynamics of community structures over five sub-periods. Sectors like banks, real estate, health care and New Shanghai take turns to comprise a few of the largest communities in different sub-periods, and more interestingly several specific sectors appear in the communities with different rank orders for returns and turnover rates even in the same sub-period. To better understand their differences, a comparison between the evolution of the returns and turnover rates of the stocks from these sectors is conducted. We find that stock prices only had large changes around important events while turnover rates surged after each of these events relevant to specific sectors, which shows strong evidence that the turnover rates are more susceptible to exogenous shocks than returns and its measurement for community detection may contain more useful information about market structure.

Nursing Personnel Turnover Rates Turned Over: Potential Positive Effects on Resident Outcomes in Nursing Homes.

ERIC Educational Resources Information Center

Halbur, Bernice T.; Fears, Neil

1986-01-01

Examines the assumed negative effects of nursing personnel turnover rates and nursing home and aggregate resident characteristics on resident discharge and death rates. Although the effects of nursing home and aggregate resident characteristics were expected, the unanticipated influence of nursing personnel turnover rates suggest that turnover…

Salary and Ranking and Teacher Turnover: A Statewide Study

ERIC Educational Resources Information Center

Garcia, Cynthia Martinez; Slate, John R.; Delgado, Carmen Tejeda

2009-01-01

This study examined three years of data obtained from the Academic Excellence Indicator System of the State of Texas regarding teacher turnover rate and teacher salary. Across all public school districts, teacher salary was consistently negatively related to teacher turnover; that is, where salary was lower, turnover rate was higher When data were…

Comparison of Reasons for Nurse Turnover in Magnet® and Non-Magnet Hospitals.

PubMed

Park, Shin Hye; Gass, Stephanie; Boyle, Diane K

2016-05-01

The aim of this study is to compare rates and reasons for registered nurse (RN) turnover by Magnet® status. Although lower RN turnover rates in Magnet hospitals have been documented well in the literature, little is known about specific separation reasons for RN turnover and whether the reasons differ between Magnet and non-Magnet hospitals. This descriptive, correlational study analyzed unit-level 2013 National Database of Nursing Quality Indicators® turnover data (2,958 units; 497 hospitals). Poisson regression and Wilcoxon-Mann-Whitney test were used. Registered nurse turnover due to environment-related reasons was higher on units in non-Magnet hospitals than units in Magnet hospitals. Units in non-Magnet hospitals had 4.684 times higher turnover rates due to staffing/workload and 1.439 times higher rates due to work schedules than did units in Magnet hospitals. Nursing administrators in both Magnet and non-Magnet hospitals need to continually strive to improve unit work environments, particularly staffing and workload conditions and work scheduling.

Local extinction and turnover rates at the edge and interior of species' ranges

USGS Publications Warehouse

Doherty, P.F.; Boulinier, T.; James., D.

2003-01-01

One hypothesis for the maintenance of the edge of a species' range suggests that more central (and abundant) populations are relatively stable and edge populations are less stable with increased local extinction and turnover rates. To date, estimates of such metrics are equivocal due to design and analysis flaws. Apparent increased estimates of extinction and turnover rates at the edge of range, versus the interior, could be a function of decreased detection probabilities alone, and not of a biological process. We estimated extinction and turnover rates for species at the interiors and edges of their ranges using an approach which incorporates potential heterogeneity in species detection probabilities. Extinction rates were higher at the edges (0.17 ?? 0.03 []) than in the interiors (0.04 ?? 0.01), as was turnover. Without taking the probability of detection into account these differences would be artificially magnified. Knowledge of extinction and turnover rates is essential in furthering our understanding of range dynamics, and in directing conservation efforts. This study further illustrates the practical application of methods proposed recently for estimating extinction rates and other community dynamic parameters.

Local extinction and turnover rates at the edge and interior of species' ranges

USGS Publications Warehouse

Doherty, P.F.; Boulinier, T.; Nichols, J.D.

2003-01-01

One hypothesis for the maintenance of the edge of a species' range suggests that more central (and abundant) populations are relatively stable and edge populations are less stable with increased local extinction and turnover rates. To date, estimates of such metrics are equivocal due to design and analysis flaws. Apparent increased estimates of extinction and turnover rates at the edge of range, versus the interior, could be a function of decreased detection probabilities alone, and not of a biological process. We estimated extinction and turnover rates for species at the interiors and edges of their ranges using an approach which incorporates potential heterogeneity in species detection probabilities. Extinction rates were higher at the edges (0.17 ' 0.03 [SE]) than in the interiors (0.04 ' 0.01), as was turnover. Without taking the probability of detection into account these differences would be artificially magnified. Knowledge of extinction and turnover rates is essential in furthering our understanding of range dynamics, and in directing conservation efforts. This study further illustrates the practical application of methods proposed recently for estimating extinction rates and other community dynamic parameters.

The rate and cost of nurse turnover in Australia.

PubMed

Roche, Michael A; Duffield, Christine M; Homer, Caroline; Buchan, James; Dimitrelis, Sofia

2015-01-01

Nurse turnover is a critical issue facing workforce planners across the globe, particularly in light of protracted and continuing workforce shortages. An ageing population coupled with the rise in complex and chronic diseases, have contributed to increased demands placed on the health system and importantly, nurses who themselves are ageing. Costs associated with nurse turnover are attracting more attention; however, existing measurements of turnover show inconsistent findings, which can be attributed to differences in study design, metrics used to calculate turnover and variations in definitions for turnover. This paper will report the rates and costs of nurse turnover across three States in Australia.

A Quantitative Spatial Proteomics Analysis of Proteome Turnover in Human Cells*

PubMed Central

Boisvert, François-Michel; Ahmad, Yasmeen; Gierliński, Marek; Charrière, Fabien; Lamont, Douglas; Scott, Michelle; Barton, Geoff; Lamond, Angus I.

2012-01-01

Measuring the properties of endogenous cell proteins, such as expression level, subcellular localization, and turnover rates, on a whole proteome level remains a major challenge in the postgenome era. Quantitative methods for measuring mRNA expression do not reliably predict corresponding protein levels and provide little or no information on other protein properties. Here we describe a combined pulse-labeling, spatial proteomics and data analysis strategy to characterize the expression, localization, synthesis, degradation, and turnover rates of endogenously expressed, untagged human proteins in different subcellular compartments. Using quantitative mass spectrometry and stable isotope labeling with amino acids in cell culture, a total of 80,098 peptides from 8,041 HeLa proteins were quantified, and their spatial distribution between the cytoplasm, nucleus and nucleolus determined and visualized using specialized software tools developed in PepTracker. Using information from ion intensities and rates of change in isotope ratios, protein abundance levels and protein synthesis, degradation and turnover rates were calculated for the whole cell and for the respective cytoplasmic, nuclear, and nucleolar compartments. Expression levels of endogenous HeLa proteins varied by up to seven orders of magnitude. The average turnover rate for HeLa proteins was ∼20 h. Turnover rate did not correlate with either molecular weight or net charge, but did correlate with abundance, with highly abundant proteins showing longer than average half-lives. Fast turnover proteins had overall a higher frequency of PEST motifs than slow turnover proteins but no general correlation was observed between amino or carboxyl terminal amino acid identities and turnover rates. A subset of proteins was identified that exist in pools with different turnover rates depending on their subcellular localization. This strongly correlated with subunits of large, multiprotein complexes, suggesting a general mechanism whereby their assembly is controlled in a different subcellular location to their main site of function. PMID:21937730

Resonant activation in a colored multiplicative thermal noise driven closed system.

PubMed

Ray, Somrita; Mondal, Debasish; Bag, Bidhan Chandra

2014-05-28

In this paper, we have demonstrated that resonant activation (RA) is possible even in a thermodynamically closed system where the particle experiences a random force and a spatio-temporal frictional coefficient from the thermal bath. For this stochastic process, we have observed a hallmark of RA phenomena in terms of a turnover behavior of the barrier-crossing rate as a function of noise correlation time at a fixed noise variance. Variance can be fixed either by changing temperature or damping strength as a function of noise correlation time. Our another observation is that the barrier crossing rate passes through a maximum with increase in coupling strength of the multiplicative noise. If the damping strength is appreciably large, then the maximum may disappear. Finally, we compare simulation results with the analytical calculation. It shows that there is a good agreement between analytical and numerical results.

Kinematic classification of non-interacting spiral galaxies

NASA Astrophysics Data System (ADS)

Wiegert, Theresa; English, Jayanne

2014-01-01

Using neutral hydrogen (HI) rotation curves of 79 galaxies, culled from the literature, as well as measured from HI data, we present a method for classifying disk galaxies by their kinematics. In order to investigate fundamental kinematic properties we concentrate on non-interacting spiral galaxies. We employ a simple parameterized form for the rotation curve in order to derive the three parameters: the maximum rotational velocity, the turnover radius and a measure of the slope of the rotation curve beyond the turnover radius. Our approach uses the statistical Hierarchical Clustering method to guide our division of the resultant 3D distribution of galaxies into five classes. Comparing the kinematic classes in this preliminary classification scheme to a number of galaxy properties, we find that our class containing galaxies with the largest rotational velocities has a mean morphological type of Sb/Sbc while the other classes tend to later types. Other trends also generally agree with those described by previous researchers. In particular we confirm correlations between increasing maximum rotational velocity and the following observed properties: increasing brightness in B-band, increasing size of the optical disk (D25) and increasing star formation rate (as derived using radio continuum data). Our analysis also suggests that lower velocities are associated with a higher ratio of the HI mass over the dynamical mass. Additionally, three galaxies exhibit a drop in rotational velocity amplitude of ≳20% after the turnover radius. However recent investigations suggest that they have interacted with minor companions which is a common cause for declining rotation curves.

Metabolism and pathophysiology of sodium and chlorine in tissue after neutron irradiation.

PubMed

Koester, L; Knopf, K; Auberger, T

1994-01-01

The photon emission of tissue was measured after radiotherapy with various doses of fission neutrons. Spectral analyses of the decay rates resulted in data for the exchange of sodium and chlorine between the irradiated tissue and the whole body. In 12 cases we found that about three fifths of Na and Cl exchange rapidly between the extravascular and vascular liquids with a turnover half-life of 13 +/- 2 min. Slowly exchangeable or non-exchangeable fractions are deposited in the soft tissue. New defined mass exchange rates for Na and Cl amount to an average of 0.8 mval min-1 kg-1 of soft tissue. The turnover of the electrolytes in tissue with large tumours is about twice that in tissues with small metastasis. Depending on dose, radiotherapy led in all cases to distinct variations of the metabolism. A maximum of the exchange of Cl combined with a minimum of Na occurs at about 85 Gy of conventional or at 10 Gy of lead-filtered fission neutron radiation. These results show directly for the first time the local response of the electrolyte metabolism to therapy.

Patterns of control of maximum metabolic rate in humans.

PubMed

Hochachka, Peter W; Beatty, Cheryl L

2003-09-01

In this analysis, four performance phenotypes were used to compare mechanisms of control of aerobic maximum metabolic rate (MMR): (i) untrained sedentary (US) subjects, as a reference group against which to compare (ii) power trained (PT), (iii) endurance trained (ET) and (iv) high altitude adapted native (HA) subject groups. Sprinters represented the PT group; long distance runners illustrated the ET group; and Quechuas represented the HA group. Numerous recent studies have identified contributors to control on both the adenosine triphosphate (ATP) supply side and the ATP demand side of ATP turnover. Control coefficients or c(i) values were defined as fractional change in MMR/fractional change in the capacity of any given step in ATP turnover. From the best available evidence it appears that at MMR all five of the major steps in energy delivery (namely, ventilation, pulmonary diffusion, cardiac output, tissue capillary - mitochondrial O(2) transfer, and aerobic cell metabolism per se) approach an upper functional ceiling, with control strength being distributed amongst the various O(2) flux steps. On the energy demand side, the situation is somewhat simplified since at MMR approximately 90% of O(2)-based ATP synthesis is used for actomyosin (AM) and Ca(2+) ATPases; at MMR these two ATP demand rates also appear to be near an upper functional ceiling. In consequence, at MMR the control contributions or c(i) values are rather evenly divided amongst all seven major steps in ATP supply and ATP demand pathways right to the point of fatigue. Relative to US (the reference group), in PT subjects at MMR control strength shifts towards O(2) delivery steps (ventilation, pulmonary diffusion and cardiac output). In contrast in ET and HA subjects at MMR control shifts towards the energy demand steps (AM and Ca(2+) ATPases), and more control strength is focussed on tissue level ATP supply and ATP demand. One obvious advantage of the ET and HA control pattern is improved metabolite homeostasis. Another possibility is that, with some reserve capacity in the O(2) delivery steps and control focussed on ATP turnover at the tissue level, nature has designed the ideal 'endurance machine'.

Control of maximum metabolic rate in humans: dependence on performance phenotypes.

PubMed

Hochachka, Peter W; Burelle, Yan

2004-01-01

Borrowing from metabolic control analysis the concept of control coefficients or ci values, defined as fractional change in MMR/fractional change in the capacity of any given step in ATP turnover, we used four performance phenotypes to compare mechanisms of control of aerobic maximum metabolic rate (MMR): (i) untrained sedentary (US) subjects, as a reference group against which to compare (ii) power trained (PT), (iii) endurance trained (ET), and (iv) high altitude adapted native (HA) subject groups. Sprinters represented the PT group; long distance runners illustrated the ET group; and Andean natives represented the HA group. Numerous recent studies have identified contributors to control on both the adenosine triphosphate (ATP) supply side and the ATP demand side of ATP turnover. From the best available evidence it appears that at MMR all five of the major steps in energy delivery (namely, ventilation, pulmonary diffusion, cardiac output, tissue capillary--mitochondrial O2 transfer, and aerobic cell metabolism per se) approach an upper functional ceiling, with control strength being distributed amongst the various O2 flux steps. On the energy demand side, the situation is somewhat simplified since at MMR approximately 90% of O2-based ATP synthesis is used for actomyosin (AM) and Ca2+ ATPases; at MMR these two ATP demand rates also appear to be near an upper functional ceiling. In consequence, at MMR the control contributions or ci values are distributed amongst all seven major steps in ATP supply and ATP demand pathways right to the point of fatigue. Relative to US (the reference group), in PT subjects at MMR control strength shifts towards O2 delivery steps (ventilation, pulmonary diffusion, and cardiac output); here physiological regulation clearly dominates MMR control. In contrast in ET and HA subjects at MMR control shifts towards the energy demand steps (AM and Ca2+ ATPases), and more control strength is focussed on tissue level ATP supply and ATP demand. One obvious advantage of the ET and HA biochemical-level control is improved metabolite homeostasis. Additionally, with some reserve capacity in the O2 delivery steps, the focussing of control on ATP turnover at the tissue level has allowed nature to improve on an 'endurance machine' design.

The Effect of Parasite Infection on Stable Isotope Turnover Rates of δ15N, δ13C and δ34S in Multiple Tissues of Eurasian Perch Perca fluviatilis.

PubMed

Yohannes, Elizabeth; Grimm, Claudia; Rothhaupt, Karl-Otto; Behrmann-Godel, Jasminca

2017-01-01

Stable isotope analysis of commercially and ecologically important fish can improve understanding of life-history and trophic ecology. However, accurate interpretation of stable isotope values requires knowledge of tissue-specific isotopic turnover that will help to describe differences in the isotopic composition of tissues and diet. We performed a diet-switch experiment using captive-reared parasite-free Eurasian perch (Perca fluviatilis) and wild caught specimens of the same species, infected with the pike tapeworm Triaenophorus nodulosus living in host liver tissue. We hypothesize that metabolic processes related to infection status play a major role in isotopic turnover and examined the influence of parasite infection on isotopic turn-over rate of carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S) in liver, blood and muscle. The δ15N and δ13C turnovers were fastest in liver tissues, followed by blood and muscle. In infected fish, liver and blood δ15N and δ13C turnover rates were similar. However, in infected fish, liver and blood δ13C turnover was faster than that of δ15N. Moreover, in infected subjects, liver δ15N and δ13C turnover rates were three to five times faster than in livers of uninfected subjects (isotopic half-life of ca.3-4 days compared to 16 and 10 days, respectively). Blood δ34S turnover rate were about twice faster in non-infected individuals implying that parasite infection could retard the turnover rate of δ34S and sulphur containing amino acids. Slower turnover rate of essential amino acid could probably decrease individual immune function. These indicate potential hidden costs of chronic and persistent infections that may have accumulated adverse effects and might eventually impair life-history fitness. For the first time, we were able to shift the isotope values of parasites encapsulated in the liver by changing the dietary source of the host. We also report variability in isotopic turnover rates between tissues, elements and between infected and parasite-free individuals. These results contribute to our understanding of data obtained from field and commercial hatcheries; and strongly improve the applicability of the stable isotope method in understanding life-history and trophic ecology of fish populations.

The Effect of Parasite Infection on Stable Isotope Turnover Rates of δ15N, δ13C and δ34S in Multiple Tissues of Eurasian Perch Perca fluviatilis

PubMed Central

Yohannes, Elizabeth; Grimm, Claudia; Rothhaupt, Karl-Otto; Behrmann-Godel, Jasminca

2017-01-01

Stable isotope analysis of commercially and ecologically important fish can improve understanding of life-history and trophic ecology. However, accurate interpretation of stable isotope values requires knowledge of tissue-specific isotopic turnover that will help to describe differences in the isotopic composition of tissues and diet. We performed a diet-switch experiment using captive-reared parasite-free Eurasian perch (Perca fluviatilis) and wild caught specimens of the same species, infected with the pike tapeworm Triaenophorus nodulosus living in host liver tissue. We hypothesize that metabolic processes related to infection status play a major role in isotopic turnover and examined the influence of parasite infection on isotopic turn-over rate of carbon (δ13C), nitrogen (δ15N) and sulphur (δ34S) in liver, blood and muscle. The δ15N and δ13C turnovers were fastest in liver tissues, followed by blood and muscle. In infected fish, liver and blood δ15N and δ13C turnover rates were similar. However, in infected fish, liver and blood δ13C turnover was faster than that of δ15N. Moreover, in infected subjects, liver δ15N and δ13C turnover rates were three to five times faster than in livers of uninfected subjects (isotopic half-life of ca.3-4 days compared to 16 and 10 days, respectively). Blood δ34S turnover rate were about twice faster in non-infected individuals implying that parasite infection could retard the turnover rate of δ34S and sulphur containing amino acids. Slower turnover rate of essential amino acid could probably decrease individual immune function. These indicate potential hidden costs of chronic and persistent infections that may have accumulated adverse effects and might eventually impair life-history fitness. For the first time, we were able to shift the isotope values of parasites encapsulated in the liver by changing the dietary source of the host. We also report variability in isotopic turnover rates between tissues, elements and between infected and parasite-free individuals. These results contribute to our understanding of data obtained from field and commercial hatcheries; and strongly improve the applicability of the stable isotope method in understanding life-history and trophic ecology of fish populations. PMID:28046021

Large benefits to marine fisheries of meeting the 1.5°C global warming target.

PubMed

Cheung, William W L; Reygondeau, Gabriel; Frölicher, Thomas L

2016-12-23

Translating the Paris Agreement to limit global warming to 1.5°C above preindustrial level into impact-related targets facilitates communication of the benefits of mitigating climate change to policy-makers and stakeholders. Developing ecologically relevant impact-related targets for marine ecosystem services, such as fisheries, is an important step. Here, we use maximum catch potential and species turnover as climate-risk indicators for fisheries. We project that potential catches will decrease by more than 3 million metric tons per degree Celsius of warming. Species turnover is more than halved when warming is lowered from 3.5° to 1.5°C above the preindustrial level. Regionally, changes in maximum catch potential and species turnover vary across ecosystems, with the biggest risk reduction in the Indo-Pacific and Arctic regions when the Paris Agreement target is achieved. Copyright © 2016, American Association for the Advancement of Science.

Paleocene floral diversities and turnover events in eastern North America and their relation to diversity models

USGS Publications Warehouse

Frederiksen, N.O.

1994-01-01

This paper uses angiosperm pollen taxon turnover (first and last appearance) and diversity events as metrics to describe the Paleocene floral history of the eastern Gulf Coast; data are from 64 samples and 67 angiosperm pollen taxa. Angiosperm pollen diversity was very low at the beginning of the Paleocene, rose slowly and then somewhat more rapidly to a maximum for the epoch in the middle of the late Paleoceneas a result of the maximum in rate of first appearances during the late early Paleocene and earliest late Paleocene. Diversity then dropped very rapidly at or near the end of the epoch as the rate of last appearances reached its maximum, resulting in the Terminal Paleocene Extinction Event. The latest Paleocene diversity decline coincided with an increase in mean annual temperature and probably in rainfall, representing the beginning of the climatic maximum for the Tertiary which characterized the early Eocene. The increase in diversity of early Paleocene floras in the eastern Gulf Coast resulted from exploitation of unfilled ecospace originating from (1) low regional diversity following the Terminal Cretaceous Extinction Event, and (2) creation of many new niches during the Paleocene, resulting, according to megafloral evidence, from a change to a new vegetation type (multistratal tropical rainforest) brought about by an increase in rainfall. The slow rate of recovery of earliest Paleocene angiosperm diversity in the eastern Gulf Coast may be explained in part by the diversity-dependence model of Carr and Kitchell (1980). However, additional factors may have contributed to the slow recovery: (1) the adverse terminal Cretaceous climates may have extended into the early Paleocene, (2) the initial Paleocene environment of the eastern Gulf Coast may have contained relatively few niches, (3) some earliest Paleocene angiosperms, particularly trees, may have had inherently poor capabilities for rapid evolution, and (4) there was a lack of significant immigration of new taxa to the region. In contrast, the earliest Eocene angiosperm flora recovered very rapidly from the Terminal Paleocene Extinction Event, and this high recovery rate resulted to a significant degree from immigration of new taxa from Europe; thus, the shape of the earliest Eocene diversity curve supports the immigration-dependence recovery model of Barry et al. (1991). ?? 1994.

Nurse turnover in New Zealand: costs and relationships with staffing practises and patient outcomes.

PubMed

North, Nicola; Leung, William; Ashton, Toni; Rasmussen, Erling; Hughes, Frances; Finlayson, Mary

2013-04-01

To determine the rates and costs of nurse turnover, the relationships with staffing practises, and the impacts on outcomes for nurses and patients. In the context of nursing shortages, information on the rates and costs of nursing turnover can improve nursing staff management and quality of care. Quantitative and qualitative data were collected prospectively for 12 months. A re-analysis of these data used descriptive statistics and correlational analysis techniques. The cost per registered nurse turnover represents half an average salary. The highest costs were related to temporary cover, followed by productivity loss. Both are associated with adverse patient events. Flexible management of nursing resources (staffing below budgeted levels and reliance on temporary cover), and a reliance on new graduates and international recruitment to replace nurses who left, contributed to turnover and costs. Nurse turnover is embedded in staffing levels and practises, with costs attributable to both. A culture of turnover was found that is inconsistent with nursing as a knowledge workforce. Nurse managers did not challenge flexible staffing practices and high turnover rates. Information on turnover and costs is needed to develop strategies that retain nurses as knowledge-based workers. © 2012 Blackwell Publishing Ltd.

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

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.

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.

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."

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

Turn-over in pulsar spectra: From young pulsars to millisecond ones

NASA Astrophysics Data System (ADS)

Kijak, J.; Lewandowski, W.; Serylak, M.

2008-02-01

The evidence for turn-over in young pulsar radio spectra at high frequencies is presented. The frequency at which a spectrum shows the maximum flux density is called the peak frequency. This peak frequency appears to depend on pulsar age and dispersion measure. A possible relation with pulsar age is interesting. Millisecond pulsars, which are very old objects, may show no evidence for spectral turn-over down to 100 MHz. Some studied pulsars with turn-over at high frequencies have been shown to have very interesting interstellar environments. This could suggest that the turn-over phenomenon is associated with the enviromental conditions around the neutron stars, rahter than being related intrinsically with the radio emission mechanism. Although there are no earlier reports of such a connection, a more detailed study on larger sample of pulsars is needed to address this idea more quantitatively. In this context, future observations below 200 MHz using LOFAR will allow us to investigate turn-over in radio pulsar spectra.

Estimation of water turnover rates of captive West Indian manatees (Trichechus manatus) held in fresh and salt water

NASA Technical Reports Server (NTRS)

Ortiz, R. M.; Worthy, G. A.; Byers, F. M.

1999-01-01

The ability of West Indian manatees (Trichechus manatus) to move between fresh and salt water raises the question of whether manatees drink salt water. Water turnover rates were estimated in captive West Indian manatees using the deuterium oxide dilution technique. Rates were quantified in animals using four experimental treatments: (1) held in fresh water and fed lettuce (N=4), (2) held in salt water and fed lettuce (N=2), (3) acutely exposed to salt water and fed lettuce (N=4), and (4) chronically exposed to salt water with limited access to fresh water and fed sea grass (N=5). Animals held in fresh water had the highest turnover rates (145+/-12 ml kg-1 day-1) (mean +/- s.e.m.). Animals acutely exposed to salt water decreased their turnover rate significantly when moved into salt water (from 124+/-15 to 65+/-15 ml kg-1 day-1) and subsequently increased their turnover rate upon re-entry to fresh water (146+/-19 ml kg-1 day-1). Manatees chronically exposed to salt water had significantly lower turnover rates (21+/-3 ml kg-1 day-1) compared with animals held in salt water and fed lettuce (45+/-3 ml kg-1 day-1). Manatees chronically exposed to salt water and fed sea grass had very low turnover rates compared with manatees held in salt water and fed lettuce, which is consistent with a lack of mariposia. Manatees in fresh water drank large volumes of water, which may make them susceptible to hyponatremia if access to a source of Na+ is not provided.

Estimation of water turnover rates of captive West Indian manatees (Trichechus manatus) held in fresh and salt water.

PubMed

Ortiz, R M; Worthy, G A; Byers, F M

1999-01-01

The ability of West Indian manatees (Trichechus manatus) to move between fresh and salt water raises the question of whether manatees drink salt water. Water turnover rates were estimated in captive West Indian manatees using the deuterium oxide dilution technique. Rates were quantified in animals using four experimental treatments: (1) held in fresh water and fed lettuce (N=4), (2) held in salt water and fed lettuce (N=2), (3) acutely exposed to salt water and fed lettuce (N=4), and (4) chronically exposed to salt water with limited access to fresh water and fed sea grass (N=5). Animals held in fresh water had the highest turnover rates (145+/-12 ml kg-1 day-1) (mean +/- s.e.m.). Animals acutely exposed to salt water decreased their turnover rate significantly when moved into salt water (from 124+/-15 to 65+/-15 ml kg-1 day-1) and subsequently increased their turnover rate upon re-entry to fresh water (146+/-19 ml kg-1 day-1). Manatees chronically exposed to salt water had significantly lower turnover rates (21+/-3 ml kg-1 day-1) compared with animals held in salt water and fed lettuce (45+/-3 ml kg-1 day-1). Manatees chronically exposed to salt water and fed sea grass had very low turnover rates compared with manatees held in salt water and fed lettuce, which is consistent with a lack of mariposia. Manatees in fresh water drank large volumes of water, which may make them susceptible to hyponatremia if access to a source of Na+ is not provided.

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.

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.

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

PubMed

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

2015-03-01

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

Stable isotopic constraints on global soil organic carbon turnover

NASA Astrophysics Data System (ADS)

Wang, Chao; Houlton, Benjamin Z.; Liu, Dongwei; Hou, Jianfeng; Cheng, Weixin; Bai, Edith

2018-02-01

Carbon dioxide release during soil organic carbon (SOC) turnover is a pivotal component of atmospheric CO2 concentrations and global climate change. However, reliably measuring SOC turnover rates on large spatial and temporal scales remains challenging. Here we use a natural carbon isotope approach, defined as beta (β), which was quantified from the δ13C of vegetation and soil reported in the literature (176 separate soil profiles), to examine large-scale controls of climate, soil physical properties and nutrients over patterns of SOC turnover across terrestrial biomes worldwide. We report a significant relationship between β and calculated soil C turnover rates (k), which were estimated by dividing soil heterotrophic respiration rates by SOC pools. ln( - β) exhibits a significant linear relationship with mean annual temperature, but a more complex polynomial relationship with mean annual precipitation, implying strong-feedbacks of SOC turnover to climate changes. Soil nitrogen (N) and clay content correlate strongly and positively with ln( - β), revealing the additional influence of nutrients and physical soil properties on SOC decomposition rates. Furthermore, a strong (R2 = 0.76; p < 0.001) linear relationship between ln( - β) and estimates of litter and root decomposition rates suggests similar controls over rates of organic matter decay among the generalized soil C stocks. Overall, these findings demonstrate the utility of soil δ13C for independently benchmarking global models of soil C turnover and thereby improving predictions of multiple global change influences over terrestrial C-climate feedback.

[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.

The nurse work environment, job satisfaction and turnover rates in rural and urban nursing units.

PubMed

Baernholdt, Marianne; Mark, Barbara A

2009-12-01

The aim of the present study was to determine whether there are differences in hospital characteristics, nursing unit characteristics, the nurse work environment, job satisfaction and turnover rates in rural and urban nursing units. Research in urban hospitals has found an association between the nurse work environment and job satisfaction and turnover rates, but this association has not been examined in rural hospitals. Rural and urban nursing units were compared in a national random sample of 97 United States hospitals (194 nursing units) with between 99 and 450 beds. Significant differences were found between hospital and nursing unit characteristics and the nurse work environment in rural and urban nursing units. Both nursing unit characteristics and the work environment were found to have a significant influence on nurse job satisfaction and turnover rates. Job satisfaction and turnover rates in rural and urban nursing units are associated with both nursing unit characteristics and the work environment. Both rural and urban hospitals can improve nurse job satisfaction and turnover rates by changing unit characteristics, such as creating better support services and a work environment that supports autonomous nursing practice. Rural hospitals can also improve the work environment by providing nurses with more educational opportunities.

Changes in alanine turnover rate due to nutritional and genetic obesity in the rat.

PubMed

Yebras, M; Salvadó, J; Arola, L; Remesar, X; Segués, T

1994-08-01

The changes in alanine turnover were determined in Zucker rats, which were either genetically obese (fa/fa) or rendered obese by dietary treatment (cafeteria fed). The whole body rate of alanine turnover was higher in genetically obese rats than in rats in which obesity was induced by diet (cafeteria). This is possibly due to variations in the rate of the amino acid incorporation into proteins, since the rate of whole body alanine degradation is the same for both groups. Thus, the different pattern followed by alanine turnover rate in these types of obese animals reflects the differences in the nitrogen economy of these animals, pointing to a higher alanine utilization in the genetically obese animals and a conservative management of alanine in the cafeteria-fed animals.

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.

Estimation of soil respiration rates and soil gas isotopic composition for the different land use of Ultisols from Calhoun CZO.

NASA Astrophysics Data System (ADS)

Cherkinsky, A.; Brecheisen, Z.; Richter, D. D., Jr.; Sheng, H.

2017-12-01

CO2 flux from soil is significant in most ecosystems and can account for more than 2/3 of total ecosystem respiration. In many cases CO2 fluxes from soil are estimated using eddy covariance techniques or the classical chamber method with measures of bulk concentrations and isotope composition of CO2. Whereas most of these studies estimate flux from the soil surface, we analyzed its concentration and isotope composition directly in soil profiles down to 8.5m depth. This experiment was conducted in Sumter National Forest in summer of 2016. The samples were collected from 3 different land use history sites: a) reference hardwood stands, mainly of oak and hickory that are taken to be never cultivated; b) cultivated plots, which were also used growing cotton prior to the 1950's but for the last 50 years for growing corn, wheat, legume, sorghum, and sunflowers; c) pine stands, which had been used for growing cotton from beginning of the 19th century and then was abandoned in 1920s and planted with loblolly pine. We have analyzed 3 replicates of each land use. There were measured in the field CO2 and O2 concentration and collected gas samples were analyzed for Δ14C, δ13C and δ18O. CO2 concentration in all types of land use has a maximum about 3m depth, approximately the same depth as the minimum of O2 concentration. Isotope analyses revealed that carbon isotopic composition tend to become lighter with the depth for all three types of land use: in cultivated site it changes from -18%o at 0.5m to -21%o at 5m; in pine site from -22%o to -25%o and in hardwood from-21.5 -24.5%o correspondently, the O2 isotopic composition does not change significantly. Based on analysis of Δ14C the turnover rate of CO2 is getting slower as depth increases. At the first 50 cm the exchange rate is the fastest on cultivated site, likely due to annual tilling, and concentration of 14C is actually equal to atmospheric. However, the turnover rate of Δ14C in soil CO2 slows down significantly as depth increases and reaches 140%o at 5m, which corresponds to a turnover rate of about 30 years. The forest sites have the same trend in the Δ14C changes; however the exchange rates are faster. For the hardwood site the turnover rate changes from about 5-10 years in the top 0.5m to about 15 years at 5m. The pine site has a slightly slower turnover rate than hardwood site but faster than cultivated site.

Characteristics of the Nursing Practice Environment Associated With Lower Unit-Level RN Turnover.

PubMed

Nelson-Brantley, Heather V; Park, Shin Hye; Bergquist-Beringer, Sandra

2018-01-01

The aim of this study is to examine characteristics of the nursing practice environment associated with lower RN turnover. Identifying characteristics of the practice environment that contribute to lower RN turnover is important for meeting the national quality strategy priority of reducing healthcare costs. Data from 1002 adult care units in 162 National Database of Nursing Quality Indicators participating hospitals were analyzed using multivariate linear regression. The Practice Environment Scale of the Nursing Work Index was used to measure practice environment characteristics. RN turnover was measured at the unit level. Nursing units with higher overall ratings of the nursing practice environment had lower rates of RN turnover. Units with higher RN perceived staffing and resource adequacy experienced significantly lower RN turnover. Unit managers and hospital administrators should consider RN perception of staffing and resource adequacy and the overall practice environment when developing targeted strategies for decreasing RN turnover.

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).

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

How Serious of a Problem is Staff Turnover in Substance Abuse Treatment? A Longitudinal Study of Actual Turnover1

PubMed Central

Eby, Lillian T.; Burk, Hannah; Maher, Charleen P.

2010-01-01

In the substance abuse treatment field, the annual turnover rate is cited as being anywhere between 19 and 50 percent (Johnson & Roman, 2002; Gallon, Gabriel, & Knudsen, 2003; Knudsen et al., 2003; McLellan et al., 2003). However, no research to date has evaluated these claims by tracking turnover longitudinally using organizational turnover data from substance abuse treatment centers. This research presents the results of a longitudinal study designed to systematically examine actual turnover among counselors and clinical supervisors. Twenty-seven geographically dispersed treatment organizations, serving a wide range of clients in the public and private sector, provided data for the study over a two year time span (2008–2009). The annual turnover rate was 33.2% for counselors and 23.4% for clinical supervisors. For both groups the majority of turnover was voluntary (employee-initiated). Specific reasons for turnover were largely consistent across the two groups, with the most common reason being a new job or new opportunity. The findings are discussed in terms of the unique employment context of substance abuse treatment. Practical recommendations are also discussed to help stem the tide of turnover in the field of substance abuse treatment. PMID:20675097

What does nurse turnover rate mean and what is the rate?

PubMed

Kovner, Christine T; Brewer, Carol S; Fatehi, Farida; Jun, Jin

2014-01-01

Registered nurse turnover is an important indicator of the nurse job market. Despite its wide use as a measure for health-care system analysis, there is a lack of consistency in the definition of turnover. Some definitions include any nurse leaving an organization; others may include involuntary and voluntary leaving. These inconsistent definitions also result in various turnover rates. The RN Work Project is a 10-year panel study of new nurses. Data were collected from the new nurses, rather than from a specific organization. About 17.5% of new nurses leave their first job within 1 year of starting their jobs. Consistent and accurate measurement of turnover is an important step in addressing organizational work environments and policies about the nursing workforce. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

The effect of changing the contact surface area between pleural liquid and pleura on the turnover of pleural liquid.

PubMed

Nakamura, T; Hara, H; Ijima, F; Arai, T; Kira, S

1984-03-01

To study the dynamics of pleural liquid, 250 ml of saline labeled with markers were injected into the pleural cavity of anesthetized dogs. For 3 h, liquid volume and concentration of these markers were measured. In a control group of dogs, the turnover rate of pleural liquid was 19.6 +/- 5.6 ml/min and lymphatic flow was 0.58 +/- 0.07 ml/min. In a group of pneumonectomized dogs, the turnover rate and lymphatic flow fell to about one fourth of those in the control group. When the left pulmonary artery was occluded, the turnover rate was halved, but lymphatic flow was not significantly different from that in the control group. These results suggest that the turnover rate of pleural liquid is dependent on the area of contact between pleural liquid and pleura and on the blood flow of the pleura. In addition, it appears that changes in pleural liquid volume are dependent on lymphatic flow.

Understanding Turnover Intentions and Behavior of Indian Information Systems Professionals: A Study of Organizational Justice, Job Satisfaction and Social Norms

ERIC Educational Resources Information Center

Iyer, Vidya V.

2011-01-01

Despite the phenomenal growth projected for the Indian information technology (IT) industry, one of the biggest challenges it faces is the high rate of turnover in offshore supplier firms based in India (Everest Research Group 2011). According to recent estimates, turnover rates among Indian information systems (IS) professionals have been…

Health insurance, cost expectations, and adverse job turnover.

PubMed

Ellis, Randall P; Albert Ma, Ching-To

2011-01-01

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

Environmental and historical imprints on beta diversity: insights from variation in rates of species turnover along gradients

PubMed Central

Fitzpatrick, Matthew C.; Sanders, Nathan J.; Normand, Signe; Svenning, Jens-Christian; Ferrier, Simon; Gove, Aaron D.; Dunn, Robert R.

2013-01-01

A common approach for analysing geographical variation in biodiversity involves using linear models to determine the rate at which species similarity declines with geographical or environmental distance and comparing this rate among regions, taxa or communities. Implicit in this approach are weakly justified assumptions that the rate of species turnover remains constant along gradients and that this rate can therefore serve as a means to compare ecological systems. We use generalized dissimilarity modelling, a novel method that accommodates variation in rates of species turnover along gradients and between different gradients, to compare environmental and spatial controls on the floras of two regions with contrasting evolutionary and climatic histories: southwest Australia and northern Europe. We find stronger signals of climate history in the northern European flora and demonstrate that variation in rates of species turnover is persistent across regions, taxa and different gradients. Such variation may represent an important but often overlooked component of biodiversity that complicates comparisons of distance–decay relationships and underscores the importance of using methods that accommodate the curvilinear relationships expected when modelling beta diversity. Determining how rates of species turnover vary along and between gradients is relevant to understanding the sensitivity of ecological systems to environmental change. PMID:23926147

The tear turnover and tear clearance tests - a review.

PubMed

Garaszczuk, Izabela K; Montes Mico, Robert; Iskander, D Robert; Expósito, Alejandro Cerviño

2018-03-01

The aim is to provide a summary of methods available for the assessment of tear turnover and tear clearance rates. The review defines tear clearance and tear turnover and describes their implication for ocular surface health. Additionally, it describes main types of techniques for measuring tear turnover, including fluorescein tear clearance tests, techniques utilizing electromagnetic spectrum and tracer molecule and novel experimental techniques utilizing optical coherence tomography and fluorescein profilometry. Areas covered: Internet databases (PubMed, Science Direct, Google Scholar) and most frequently cited references were used as a principal resource of information on tear turnover rate and tear clearance rate, presenting methodologies and equipment, as well as their definition and implications for the anterior eye surface health and function. Keywords used for data-search were as follows: tear turnover, tear clearance, fluorescein clearance, scintigraphy, fluorophotometry, tear flow, drainage, tear meniscus dynamics, Krehbiel flow and lacrimal functional unit. Expert commentary: After decades, the topic of tear turnover assessment has been reintroduced. Recently, new techniques have been developed to propose less invasive, less time consuming and simpler methodologies for the assessment of tear dynamics that have the potential to be utilized in clinical practice.

Multiperspective analysis of workforce challenges and their effects on consumer and family quality of life.

PubMed

Larson, Sheryl A; Hewitt, Amy S; Lakin, K Charlie

2004-11-01

The impacts of direct support professional turnover, wages, and vacancy rates as reported in interviews with 372 adult service recipients and 20 county managers and surveys of 183 families, 520 service coordinators, 228 direct support professionals, and 184 residential and 82 vocational managers were examined. Direct support professional turnover, wages, and vacancy rates were reported to be barriers to high quality supports, serving people waiting for services, and providing in-home or respite services. Higher direct support professional turnover was associated with lower wages and supports in urban counties. Multivariate analyses of covariance revealed a complex pattern of significant associations between quality of life outcomes; level of mental retardation, medical status, site size (for vocational settings); and direct support professional vacancy rates, average wage, and turnover rates.

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.

Characterization of the mammalian miRNA turnover landscape

PubMed Central

Guo, Yanwen; Liu, Jun; Elfenbein, Sarah J.; Ma, Yinghong; Zhong, Mei; Qiu, Caihong; Ding, Ye; Lu, Jun

2015-01-01

Steady state cellular microRNA (miRNA) levels represent the balance between miRNA biogenesis and turnover. The kinetics and sequence determinants of mammalian miRNA turnover during and after miRNA maturation are not fully understood. Through a large-scale study on mammalian miRNA turnover, we report the co-existence of multiple cellular miRNA pools with distinct turnover kinetics and biogenesis properties and reveal previously unrecognized sequence features for fast turnover miRNAs. We measured miRNA turnover rates in eight mammalian cell types with a combination of expression profiling and deep sequencing. While most miRNAs are stable, a subset of miRNAs, mostly miRNA*s, turnovers quickly, many of which display a two-step turnover kinetics. Moreover, different sequence isoforms of the same miRNA can possess vastly different turnover rates. Fast turnover miRNA isoforms are enriched for 5′ nucleotide bias against Argonaute-(AGO)-loading, but also additional 3′ and central sequence features. Modeling based on two fast turnover miRNA*s miR-222-5p and miR-125b-1-3p, we unexpectedly found that while both miRNA*s are associated with AGO, they strongly differ in HSP90 association and sensitivity to HSP90 inhibition. Our data characterize the landscape of genome-wide miRNA turnover in cultured mammalian cells and reveal differential HSP90 requirements for different miRNA*s. Our findings also implicate rules for designing stable small RNAs, such as siRNAs. PMID:25653157

Missed nursing care: the impact on intention to leave and turnover.

PubMed

Tschannen, Dana; Kalisch, Beatrice J; Lee, Kyung Hee

2010-12-01

The purpose of the study was to examine the relationship between missed nursing care, nurse turnover, and intention to leave. A cross-sectional study using the MISSCARE Survey was conducted. The sample comprised 110 patient-care units in 10 acute-care hospitals. Staffing data, turnover rates, and unit-level Case Mix Index were collected from the participating hospitals. Higher percentages of females on the unit were associated with lower turnover rates (beta = -.235, p = .010). Units with higher rates of missed care (beta = .302, p < .0001) and absenteeism (beta = .247, p = .034) had more staff with intention to leave. Units with nursing staffwho worked overtime (beta = -.283, p = .001) and who were over 35 years of age (beta = -.270, p = .050) were less likely to have staff with intention to leave. By minimizing missed nursing care, organizations may be able to improve satisfaction and reduce intention to leave (and subsequent turnover).

In Situ Determination of Sulfide Turnover Rates in a Meromictic Alpine Lake

PubMed Central

Lüthy, Lucas; Fritz, Markus; Bachofen, Reinhard

2000-01-01

A push-pull method, previously used in groundwater analyses, was successfully adapted for measuring sulfide turnover rates in situ at different depths in the meromictic Lake Cadagno. In the layer of phototrophic bacteria at about 12 m in depth net sulfide consumption was observed during the day, indicating active bacterial photosynthesis. During the night the sulfide turnover rates were positive, indicating a net sulfide production from the reduction of more-oxidized sulfur compounds. Because of lack of light, no photosynthesis takes place in the monimolimnion; thus, only sulfide formation is observed both during the day and the night. Sulfide turnover rates in the oxic mixolimnion were always positive as sulfide is spontaneously oxidized by oxygen and as the rates of sulfide oxidation depend on the oxygen concentrations present. Sulfide oxidation by chemolithotrophic bacteria may occur at the oxicline, but this cannot be distinguished from spontaneous chemical oxidation. PMID:10653740

Nurse Knowledge, Work Environment, and Turnover in Highly Specialized Pediatric End-of-Life Care.

PubMed

Lindley, Lisa C; Cozad, Melanie J

2017-07-01

To examine the relationship between nurse knowledge, work environment, and registered nurse (RN) turnover in perinatal hospice and palliative care organizations. Using nurse intellectual capital theory, a multivariate analysis was conducted with 2007 National Home and Hospice Care Survey data. Perinatal hospice and palliative care organizations experienced a 5% turnover rate. The professional experience of advanced practice nurses (APNs) was significantly related to turnover among RNs (β = -.032, P < .05). Compared to organizations with no APNs professional experience, clinical nurse specialists and nurse practitioners significantly reduced RN turnover by 3 percentage points. No other nurse knowledge or work environment variables were associated with RN turnover. Several of the control variables were also associated with RN turnover in the study; Organizations serving micropolitan (β = -.041, P < .05) and rural areas (β = -.037, P < .05) had lower RN turnover compared to urban areas. Organizations with a technology climate where nurses used electronic medical records had a higher turnover rate than those without (β = .036, P < .05). The findings revealed that advanced professional experience in the form of APNs was associated with reductions in RN turnover. This suggests that having a clinical nurse specialist or nurse practitioner on staff may provide knowledge and experience to other RNs, creating stability within the organization.

Photocatalytic water oxidation by a pyrochlore oxide upon irradiation with visible light: rhodium substitution into yttrium titanate.

PubMed

Kiss, Borbala; Didier, Christophe; Johnson, Timothy; Manning, Troy D; Dyer, Matthew S; Cowan, Alexander J; Claridge, John B; Darwent, James R; Rosseinsky, Matthew J

2014-12-22

A stable visible-light-driven photocatalyst (λ≥450 nm) for water oxidation is reported. Rhodium substitution into the pyrochlore Y2 Ti2 O7 is demonstrated by monitoring Vegard's law evolution of the unit-cell parameters with changing rhodium content, to a maximum content of 3 % dopant. Substitution renders the solid solutions visible-light active. The overall rate of oxygen evolution is comparable to WO3 but with superior light-harvesting and surface-area-normalized turnover rates, making Y2 Ti1.94 Rh0.06 O7 an excellent candidate for use in a Z-scheme water-splitting system. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A longitudinal study of the moderating role of extraversion: leader-member exchange, performance, and turnover during new executive development.

PubMed

Bauer, Talya N; Erdogan, Berrin; Liden, Robert C; Wayne, Sandy J

2006-03-01

Identifying factors that help or hinder new executives in "getting up to speed" quickly and remaining with an organization is vital to maximizing the effectiveness of executive development. The current study extends past research by examining extraversion as a moderator of relationships between leader-member exchange (LMX) and performance, turnover intentions, and actual turnover for an executive sample. The sample consisted of 116 new executives who were surveyed prior to starting their employment and at 3 months postentry. A total of 67 senior executives rated these new executives in terms of overall performance at 6 months postentry. Turnover data were gathered from company records 3 1/2 years later. Hierarchical regression results showed that LMX was not related to performance or turnover intentions for those high in extraversion; but for individuals low in extraversion, there was a relation between LMX, performance, and turnover intentions. Furthermore, survival analyses showed that LMX was only related to turnover-hazard rate for individuals low in extraversion.

The role of climate in the global patterns of ecosystem carbon turnover rates - contrasts between data and models

NASA Astrophysics Data System (ADS)

Carvalhais, N.; Forkel, M.; Khomik, M.; Bellarby, J.; Migliavacca, M.; Thurner, M.; Beer, C.; Jung, M.; Mu, M.; Randerson, J. T.; Saatchi, S. S.; Santoro, M.; Reichstein, M.

2012-12-01

The turnover rates of carbon in terrestrial ecosystems and their sensitivity to climate are instrumental properties for diagnosing the interannual variability and forecasting trends of biogeochemical processes and carbon-cycle-climate feedbacks. We propose to globally look at the spatial distribution of turnover rates of carbon to explore the association between bioclimatic regimes and the rates at which carbon cycles in terrestrial ecosystems. Based on data-driven approaches of ecosystem carbon fluxes and data-based estimates of ecosystem carbon stocks it is possible to build fully observationally supported diagnostics. These data driven diagnostics support the benchmarking of CMIP5 model outputs (Coupled Model Intercomparison Project Phase 5) with observationally based estimates. The models' performance is addressed by confronting spatial patterns of carbon fluxes and stocks with data, as well as the global and regional sensitivities of turnover rates to climate. Our results show strong latitudinal gradients globally, mostly controlled by temperature, which are not always paralleled by CMIP5 simulations. In northern colder regions is also where the largest difference in temperature sensitivity between models and data occurs. Interestingly, there seem to be two different statistical populations in the data (some with high, others with low apparent temperature sensitivity of carbon turnover rates), where the different models only seem to describe either one or the other population. Additionally, the comparisons within bioclimatic classes can even show opposite patterns between turnover rates and temperature in water limited regions. Overall, our analysis emphasizes the role of finding patterns and intrinsic properties instead of plain magnitudes of fluxes for diagnosing the sensitivities of terrestrial biogeochemical cycles to climate. Further, our regional analysis suggests a significant gap in addressing the partial influence of water in the ecosystem carbon turnover rates especially in very cold or water limited regions.

Flight metabolism in relation to speed in Chiroptera: testing the U-shape paradigm in the short-tailed fruit bat Carollia perspicillata.

PubMed

von Busse, Rhea; Swartz, Sharon M; Voigt, Christian C

2013-06-01

Aerodynamic theory predicts that flight for fixed-wing aircraft requires more energy at low and high speeds compared with intermediate speeds, and this theory has often been extended to predict speed-dependent metabolic rates and optimal flight speeds for flying animals. However, the theoretical U-shaped flight power curve has not been robustly tested for Chiroptera, the only mammals capable of flapping flight. We examined the metabolic rate of seven Seba's short-tailed fruit bats (Carollia perspicillata) during unrestrained flight in a wind tunnel at air speeds from 1 to 7 m s(-1). Following intra-peritoneal administration of (13)C-labeled Na-bicarbonate, we measured the enrichment in (13)C of exhaled breath before and after flight. We converted fractional turnover of (13)C into metabolic rate and power, based on the assumption that bats oxidized glycogen during short flights. Power requirements of flight varied with air speed in a U-shaped manner in five out of seven individuals, whereas energy turnover was not related to air speed in two individuals. Power requirements of flight were close to values predicted by Pennycuick's aerodynamic model for minimum power speed, but differed for maximum range speed. The results of our experiment support the theoretical expectation of a U-shaped power curve for flight metabolism in a bat.

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.

Turnover of Grassland Roots in Mountain Ecosystems Revealed by Their Radiocarbon Signature: Role of Temperature and Management

PubMed Central

Leifeld, Jens; Meyer, Stefanie; Budge, Karen; Sebastia, Maria Teresa; Zimmermann, Michael; Fuhrer, Juerg

2015-01-01

Root turnover is an important carbon flux component in grassland ecosystems because it replenishes substantial parts of carbon lost from soil via heterotrophic respiration and leaching. Among the various methods to estimate root turnover, the root’s radiocarbon signature has rarely been applied to grassland soils previously, although the value of this approach is known from studies in forest soils. In this paper, we utilize the root’s radiocarbon signatures, at 25 plots, in mountain grasslands of the montane to alpine zone of Europe. We place the results in context of a global data base on root turnover and discuss driving factors. Root turnover rates were similar to those of a subsample of the global data, comprising a similar temperature range, but measured with different approaches, indicating that the radiocarbon method gives reliable, plausible and comparable results. Root turnover rates (0.06–1.0 y-1) scaled significantly and exponentially with mean annual temperatures. Root turnover rates indicated no trend with soil depth. The temperature sensitivity was significantly higher in mountain grassland, compared to the global data set, suggesting additional factors influencing root turnover. Information on management intensity from the 25 plots reveals that root turnover may be accelerated under intensive and moderate management compared to low intensity or semi-natural conditions. Because management intensity, in the studied ecosystems, co-varied with temperature, estimates on root turnover, based on mean annual temperature alone, may be biased. A greater recognition of management as a driver for root dynamics is warranted when effects of climatic change on belowground carbon dynamics are studied in mountain grasslands. PMID:25734640

Changes in turnover and vacancy rates of care workers in England from 2008 to 2010: panel analysis of national workforce data.

PubMed

Hussein, Shereen; Ismail, Mohamed; Manthorpe, Jill

2016-09-01

The combination of growing demand for long-term care and higher expectations of care staff needs to be set in the context of long-standing concerns about the sustainability of recruitment and retention of front-line staff in the United Kingdom. Organisational and work environment factors are associated with vacancy levels and turnover rates. The aim of the current analysis was to investigate changes in turnover and vacancy rates over time experienced by a sample of social care employers in England. Taking a follow-up approach offers potentially more accurate estimates of changes in turnover and vacancy rates, and enables the identification of any different organisational characteristics which may be linked to reductions in these elements over time. The study constructed a panel of 2964 care providers (employers) using 18 separate data sets from the National Minimum Data Set for Social Care during 2008-2010. The findings indicate slight reductions in vacancy rates but the presence of enduring, high turnover rates among direct care workers over the study period. However, the experience of individual employers varied, with home-care providers experiencing significantly higher turnover rates than other parts of the sector. These findings raise questions around the quality and motivations of new recruits and methods of reducing specific vacancy levels. At a time of increased emphasis on care at home, it is worthwhile examining why care homes appear to have greater stability of staff and fewer vacancies than home-care agencies. © 2015 The Authors. Health and Social Care in the Community Published by John Wiley & Sons Ltd.

Carbon and nitrogen stable isotope turnover rates and diet-tissue discrimination in Florida manatees (Trichechus manatus latirostris).

PubMed

Alves-Stanley, Christy D; Worthy, Graham A J

2009-08-01

The Florida manatee (Trichechus manatus latirostris) is a herbivorous marine mammal that occupies freshwater, estuarine and marine habitats. Despite being considered endangered, relatively little is known about its feeding ecology. The present study expands on previous work on manatee feeding ecology by providing critical baseline parameters for accurate isotopic data interpretation. Stable carbon and nitrogen isotope ratios were examined over a period of more than 1 year in the epidermis of rescued Florida manatees that were transitioning from a diet of aquatic forage to terrestrial forage (lettuce). The mean half-life for (13)C turnover was 53 and 59 days for skin from manatees rescued from coastal and riverine regions, respectively. The mean half-life for (15)N turnover was 27 and 58 days, respectively. Because of these slow turnover rates, carbon and nitrogen stable isotope analysis in manatee epidermis is useful in summarizing average dietary intake over a long period of time rather than assessing recent diet. In addition to turnover rate, a diet-tissue discrimination value of 2.8 per thousand for (13)C was calculated for long-term captive manatees on a lettuce diet. Determining both turnover rate and diet-tissue discrimination is essential in order to accurately interpret stable isotope data.

Survival analysis to measure turnover of the medical education workforce in Ethiopia.

PubMed

Assefa, Tsion; Haile Mariam, Damen; Mekonnen, Wubegzier; Derbew, Miliard

2017-03-14

Until recently, there were only a few medical schools in Ethiopia. However, currently, in response to the apparent shortage in physician workforce, the country has made huge progress with respect to the expansion of medical schools, by adopting the so-called flooding strategy. Nevertheless, the effectiveness of the intended strategy also relies on physician accessibility and turnover. Therefore, the aim of this study was to examine the distribution of physicians in the medical schools of Ethiopia and to quantify the magnitude and identify factors associated with physician turnover. This organizational faculty physician workforce survey was conducted in seven government-owned medical schools in Ethiopia. Longitudinal medical workforce data set of about 6 years (between September 2009 and June 2015) were retrospectively collected from each of the medical schools. The observation time begins with the date of employment (time zero) and ends at the date on which the physician leaves the appointment/or the data collection date. Kaplan-Meier survival method was used to describe the duration of stay of physicians in the academic health care settings. A Cox proportional hazards (CPH) model was fitted to identify the risk factors for physician turnover. In this study, a total of 1258 faculty physicians were observed in seven medical schools which resulted in 6670.5 physician-years. Of the total, there were 198 (15.7%) turnover events and the remaining 1060 (84.3%) were censored. The average turnover rate is about 29.7 per 1000 physician-years of observations. Multivariate modeling revealed no statistical significant difference in the rate of turnover between males and females (adjusted hazard ratio (AHR), 1.12; 95%CI, 0.71, 1.80). However, a lower rate of physician turnover was observed among those who were born before 1975 (AHR, 0.37; 95%CI, 0.20, 0.69) compared with those who were born after 1985. Physicians with the academic rank of associate professor and above had a lower (AHR, 0.25; 95%CI, 0.11, 0.60) rate of turnover in comparison to lecturers. In addition, physicians working in Jimma University had 1.66 times higher rate of turnover compared with those working in Addis Ababa University. However, the model showed a significantly lower rate of turnover in Mekelle (AHR, 0.16; 95%CI, 0.06, 0.41) and University of Gondar (AHR, 0.46; 95%CI, 0.25, 0.84) compared with that of Addis Ababa. Physician turnover in the remaining medical schools (Bahir Dar, Haromaya, and Hawassa) did not show a statistically significant difference with Addis Ababa University (P > 0.05). This study revealed a strong association between physician turnover with age, academic rank, and workplace. Therefore, the findings of the study have important implications in that attention needs to be given for the needs of faculty physicians and for improving the work environment in order to achieve a high level of retention.

Physician and staff turnover in community primary care practice.

PubMed

Ruhe, Mary; Gotler, Robin S; Goodwin, Meredith A; Stange, Kurt C

2004-01-01

The effect of a rapidly changing healthcare system on personnel turnover in community family practices has not been analyzed. We describe physician and staff turnover and examine its association with practice characteristics and patient outcomes. A cross-sectional evaluation of length of employment of 150 physicians and 762 staff in 77 community family practices in northeast Ohio was conducted. Research nurses collected data using practice genograms, key informant interviews, staff lists, practice environment checklists, medical record reviews, and patient questionnaires. The association of physician and staff turnover with practice characteristics, patient satisfaction, and preventive service data was tested. During a 2-year period, practices averaged a 53% turnover rate of staff. The mean length of duration of work at the current practice location was 9.1 years for physicians and 4.1 years for staff. Longevity varied by position, with a mean of 3.4 years for business employees, 4.0 years for clinical employees, and 7.8 years for office managers. Network-affiliated practices experienced higher turnover than did independent practices. Physician longevity was associated with a practice focus on managing chronic illness, keeping on schedule, and responding to insurers' requests. No association was found between turnover and patient satisfaction or preventive service delivery rates. Personnel turnover is pervasive in community primary care practices and is associated with employee role, practice network affiliation, and practice focus. The potentially disruptive effect of personnel turnover on practice functioning, finances, and longitudinal relationships with patients deserves further study despite the reassuring lack of association with patient satisfaction and preventive service delivery rates.

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.

Nurse knowledge, work environment, and turnover in highly specialized pediatric end-of-life care

PubMed Central

Lindley, Lisa C.; Cozad, Melanie J.

2016-01-01

Objective To examine the relationship between nurse knowledge and work environment and Registered Nurse (RN) turnover in perinatal hospice and palliative care organizations. Methods Using nurse intellectual capital theory, a multivariate analysis was conducted with 2007 National Home and Hospice Care Survey data. Results Perinatal hospice and palliative care organizations experienced a 5% turnover rate. The professional experience of advanced practice nurses (APNs) was significantly related to turnover among RNs (β= −0.032, P< 0.05). Compared to organizations with no APNs professional experience, clinical nurse specialists and nurse practitioners significantly reduced RN turnover by 3-percentage points. No other nurse knowledge or work environment variables were associated with RN turnover. Several of the control variables were also associated with RN turnover in the study: organizations serving micropolitan (β= −0.041, P< 0.05) and rural areas (β= −0.037, P< 0.05) had lower RN turnover, compared to urban areas. Organizations with a technology climate where nurses used electronic medical records had a higher turnover rate than those without (β= 0.036, P< 0.05). Conclusions The findings revealed that advanced professional experience in the form of APNs were associated with reductions in RN turnover. This suggests that having a clinical nurse specialist or nurse practitioner on staff may provide knowledge and experience to other RNs, creating stability within the organization. PMID:27188758

How serious of a problem is staff turnover in substance abuse treatment? A longitudinal study of actual turnover.

PubMed

Eby, Lillian T; Burk, Hannah; Maher, Charleen P

2010-10-01

In the substance abuse treatment field, the annual turnover rate is cited as being anywhere between 19% and 50% (J.A. Johnson & P.M. Roman, 2002; S.L. Gallon, R.M. Gabriel, J.R.W. Knudsen, 2003; H.K. Knudsen, J.A. Johnson, & P.M. Roman, 2003; A.T. McLellan, D. Carise, & H.D. Kleber, 2003). However, no research to date has evaluated these claims by tracking turnover longitudinally using organizational turnover data from substance abuse treatment centers. This research presents the results of a longitudinal study designed to systematically examine actual turnover among counselors and clinical supervisors. Twenty-seven geographically dispersed treatment organizations, serving a wide range of clients in the public and private sector, provided data for the study over a 2-year time span (2008-2009). The annual turnover rate was 33.2% for counselors and 23.4% for clinical supervisors. For both groups, the majority of turnover was voluntary (employee-initiated). Specific reasons for turnover were largely consistent across the two groups, with the most common reason being a new job or new opportunity. The findings are discussed in terms of the unique employment context of substance abuse treatment. Practical recommendations are also discussed to help stem the tide of turnover in the field of substance abuse treatment. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Special K: testing the potassium link between radioactive rubidium (86Rb) turnover and metabolic rate.

PubMed

Tomlinson, Sean; Mathialagan, Priya D; Maloney, Shane K

2014-04-01

The measurement of (86)Rb turnover recently has been suggested as a useful method for measuring field metabolic rate in small animals. We investigated a proposed mechanism of (86)Rb turnover, its analogy to K(+), by comparing the turnover of (86)Rb in a model insect, the rhinoceros beetle Xylotrupes gideon, fed a diet of plum jam or plum jam enriched with K(+) or Rb(+). The turnover of (86)Rb in the beetles on the K(+) and the Rb(+) diets was higher than that for beetles on the jam diet (F2,311=32.4; P=1.58×10(-13)). We also exposed the beetles to different ambient temperatures to induce differences in metabolic rate ( ) while feeding them the jam and K(+) diets. was higher at higher ambient temperature (Ta) for both jam (F1,11=14.56; P=0.003) and K(+) (F1,8=15.39; P=0.004) dietary groups, and the turnover of (86)Rb was higher at higher Ta for both jam (F1,11=10.80; P=0.007) and K(+) (F1,8=12.34; P=0.008) dietary groups. There was a significant relationship between (86)Rb turnover and for both the jam (F1,11=35.00; P=1.0×10(-3)) and the K(+) (F1,8=64.33; P=4.3×10(-5)) diets, but the relationship differed between the diets (F1,19=14.07; P=0.001), with a higher (86)Rb turnover in beetles on the K(+)-enriched than on the jam diet at all Ta. We conclude that (86)Rb turnover is related to K(+) metabolism, and that this is the mechanism of the relationship between (86)Rb turnover and . Studies relating (86)Rb turnover to should maintain dietary [K] as close as possible to that of natural diets for the most accurate calibrations for free-ranging animals.

Listening to the Voices of Children in Foster Care: Youths Speak out about Child Welfare Workforce Turnover and Selection

ERIC Educational Resources Information Center

Strolin-Goltzman, Jessica; Kollar, Sharon; Trinkle, Joanne

2010-01-01

Child welfare workforce turnover rates across private and public child welfare agencies are concerning. Although research about the causes of child welfare workforce turnover has been plentiful, empirical studies on the effects of turnover on child outcomes are sparse. Furthermore, the voices and experiences of youths within the system have been…

Turnover of registered nurses in Israel: characteristics and predictors.

PubMed

Toren, Orly; Zelker, Revital; Lipschuetz, Michal; Riba, Shoshana; Reicher, Sima; Nirel, Nurit

2012-05-01

In an era of global and local nursing shortages, nursing turnover has negative consequences in terms of diminished quality of care, increased costs and economic losses and decreased job satisfaction. To examine the turnover rate of registered nurses in Israel by assessing the varying degree of turnover between economic sectors, between hospital and community facilities, and/or between types of hospitals; and by examining potential predicting factors of turnover among registered nurses. A national phone survey was undertaken in Israel consisting of a random sampling of registered nurses of working age (up to age 60). The subjects comprised 10% of a national database of 32,000 registered nurses. The turnover rate among working nurses in Israel currently stands at 23%. In addition, 13% of employed nurses have taken a temporary leave of absence for a period greater than 6 months in the past 10 years, most up to 1 year. While job satisfaction rates were relatively high (72%), Professional satisfaction rates were 60% with no significant difference between hospital and community nurses. The turnover rate of registered nurses from a hospital setting to the community was significantly higher (p<.01) than that of community registered nurses to hospitals. Predicting factors of turnover were found to be: young age, part-time work, lack of advanced professional education, academic education and low satisfaction with the nursing profession. The shift of nursing workforce is mainly from hospitals to community health settings. There is a need to monitor and understand the characteristics of job and professional satisfaction among hospital nurses in order to implement crucial organizational interventions and retain hospital nursing staffs. Since young nurses, nurses working part time and nurses with no advanced professional and academic education, tend to move more than others, efforts should be targeted at these specific groups. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Tissue Turnover Rates and Isotopic Trophic Discrimination Factors in the Endothermic Teleost, Pacific Bluefin Tuna (Thunnus orientalis)

PubMed Central

Madigan, Daniel J.; Litvin, Steven Y.; Popp, Brian N.; Carlisle, Aaron B.; Farwell, Charles J.; Block, Barbara A.

2012-01-01

Stable isotope analysis (SIA) of highly migratory marine pelagic animals can improve understanding of their migratory patterns and trophic ecology. However, accurate interpretation of isotopic analyses relies on knowledge of isotope turnover rates and tissue-diet isotope discrimination factors. Laboratory-derived turnover rates and discrimination factors have been difficult to obtain due to the challenges of maintaining these species in captivity. We conducted a study to determine tissue- (white muscle and liver) and isotope- (nitrogen and carbon) specific turnover rates and trophic discrimination factors (TDFs) using archived tissues from captive Pacific bluefin tuna (PBFT), Thunnus orientalis, 1–2914 days after a diet shift in captivity. Half-life values for 15N turnover in white muscle and liver were 167 and 86 days, and for 13C were 255 and 162 days, respectively. TDFs for white muscle and liver were 1.9 and 1.1‰ for δ 15N and 1.8 and 1.2‰ for δ 13C, respectively. Our results demonstrate that turnover of 15N and 13C in bluefin tuna tissues is well described by a single compartment first-order kinetics model. We report variability in turnover rates between tissue types and their isotope dynamics, and hypothesize that metabolic processes play a large role in turnover of nitrogen and carbon in PBFT white muscle and liver tissues. 15N in white muscle tissue showed the most predictable change with diet over time, suggesting that white muscle δ 15N data may provide the most reliable inferences for diet and migration studies using stable isotopes in wild fish. These results allow more accurate interpretation of field data and dramatically improve our ability to use stable isotope data from wild tunas to better understand their migration patterns and trophic ecology. PMID:23145128

Collagen turnover in normal and degenerate human intervertebral discs as determined by the racemization of aspartic acid.

PubMed

Sivan, Sarit-Sara; Wachtel, Ellen; Tsitron, Eve; Sakkee, Nico; van der Ham, Frits; Degroot, Jeroen; Roberts, Sally; Maroudas, Alice

2008-04-04

Knowledge of rates of protein turnover is important for a quantitative understanding of tissue synthesis and catabolism. In this work, we have used the racemization of aspartic acid as a marker for the turnover of collagen obtained from healthy and pathological human intervertebral disc matrices. We measured the ratio of the d- and l-isomers in collagen extracted from these tissues as a function of age between 16 and 77 years. For collagen taken from healthy discs, the fractional increase of d-Asp was found to be 6.74 x 10(-4)/year; for degenerate discs, the corresponding rate was 5.18 x 10(-4)/year. Using the racemization rate found previously for the stable population of collagen molecules in dentin, we found that the rate of collagen turnover (k(T)) in discs is not constant but rather a decreasing function of age. The average turnover rate in normal disc between the ages of 20 and 40 is 0.00728 +/- 0.00275/year, and that between the ages of 50 and 80 is 0.00323 +/- 0.000947/year, which correspond to average half-lives of 95 and 215 years, respectively. Turnover of collagen from degenerate discs may be more rapid than that found for normal discs; however, statistical analysis leaves this point uncertain. The finding of a similar correlation between the accumulation of d-Asp and that of pentosidine for three normal collagenous tissues further supports the idea that the accumulation of pentosidine in a particular tissue can, along with the racemization of aspartic acid, be used as a reliable measure of protein turnover.

Analysis and control of employee turnover.

PubMed

McConnell, Charles R

2007-01-01

Turnover is a relatively simple and easily described 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 which can be corrected and some which 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.

Selective logging: do rates of forest turnover in stems, species composition and functional traits decrease with time since disturbance? – A 45 year perspective

PubMed Central

Osazuwa-Peters, Oyomoare L.; Jiménez, Iván; Oberle, Brad; Chapman, Colin A.; Zanne, Amy E.

2015-01-01

Selective logging, the targeted harvesting of timber trees in a single cutting cycle, is globally rising in extent and intensity. Short-term impacts of selective logging on tropical forests have been widely investigated, but long-term effects on temporal dynamics of forest structure and composition are largely unknown. Understanding these long-term dynamics will help determine whether tropical forests are resilient to selective logging and inform choices between competing demands of anthropogenic use versus conservation of tropical forests. Forest dynamics can be studied within the framework of succession theory, which predicts that temporal turnover rates should decline with time since disturbance. Here, we investigated the temporal dynamics of a tropical forest in Kibale National Park, Uganda over 45 years following selective logging. We estimated turnover rates in stems, species composition, and functional traits (wood density and diameter at breast height), using observations from four censuses in 1989, 1999, 2006, and 2013, of stems ≥ 10 cm diameter within 17 unlogged and 9 logged 200 × 10 m vegetation plots. We used null models to account for interdependencies among turnover rates in stems, species composition, and functional traits. We tested predictions that turnover rates should be higher and decrease with increasing time since the selective logging event in logged forest, but should be less temporally variable in unlogged forest. Overall, we found higher turnover rates in logged forest for all three attributes, but turnover rates did not decline through time in logged forest and was not less temporally variable in unlogged forest. These results indicate that successional models that assume recovery to pre-disturbance conditions are inadequate for predicting the effects of selective logging on the dynamics of the tropical forest in Kibale. Selective logging resulted in persistently higher turnover rates, which may compromise the carbon storage capacity of Kibale’s forest. Selective logging effects may also interact with effects from other global trends, potentially causing major long-term shifts in the dynamics of tropical forests. Similar studies in tropical forests elsewhere will help determine the generality of these conclusions. Ultimately, the view that selective logging is a benign approach to the management of tropical forests should be reconsidered in the light of studies of the effects of this practice on long-term forest dynamics. PMID:26339115

Selective logging: do rates of forest turnover in stems, species composition and functional traits decrease with time since disturbance? - A 45 year perspective.

PubMed

Osazuwa-Peters, Oyomoare L; Jiménez, Iván; Oberle, Brad; Chapman, Colin A; Zanne, Amy E

2015-12-01

Selective logging, the targeted harvesting of timber trees in a single cutting cycle, is globally rising in extent and intensity. Short-term impacts of selective logging on tropical forests have been widely investigated, but long-term effects on temporal dynamics of forest structure and composition are largely unknown. Understanding these long-term dynamics will help determine whether tropical forests are resilient to selective logging and inform choices between competing demands of anthropogenic use versus conservation of tropical forests. Forest dynamics can be studied within the framework of succession theory, which predicts that temporal turnover rates should decline with time since disturbance. Here, we investigated the temporal dynamics of a tropical forest in Kibale National Park, Uganda over 45 years following selective logging. We estimated turnover rates in stems, species composition, and functional traits (wood density and diameter at breast height), using observations from four censuses in 1989, 1999, 2006, and 2013, of stems ≥ 10 cm diameter within 17 unlogged and 9 logged 200 × 10 m vegetation plots. We used null models to account for interdependencies among turnover rates in stems, species composition, and functional traits. We tested predictions that turnover rates should be higher and decrease with increasing time since the selective logging event in logged forest, but should be less temporally variable in unlogged forest. Overall, we found higher turnover rates in logged forest for all three attributes, but turnover rates did not decline through time in logged forest and was not less temporally variable in unlogged forest. These results indicate that successional models that assume recovery to pre-disturbance conditions are inadequate for predicting the effects of selective logging on the dynamics of the tropical forest in Kibale. Selective logging resulted in persistently higher turnover rates, which may compromise the carbon storage capacity of Kibale's forest. Selective logging effects may also interact with effects from other global trends, potentially causing major long-term shifts in the dynamics of tropical forests. Similar studies in tropical forests elsewhere will help determine the generality of these conclusions. Ultimately, the view that selective logging is a benign approach to the management of tropical forests should be reconsidered in the light of studies of the effects of this practice on long-term forest dynamics.

Long term effects of fire on the carbon balance in boreal forests

NASA Astrophysics Data System (ADS)

Berninger, Frank; Köster, Kaja; Pumpanen, Jukka

2013-04-01

Fire is the primary process which organizes the physical and biological attributes of the boreal biome and influences energy flows and biogeochemical cycles, particularly the carbon and nitrogen cycle. We established a forest fire chronosequence in the northern boreal forest in Lapland (Värriö Strict Nature Reserve), Finland (67°46' N, 29°35' E) that spans 160 years. Soil organic matter and its turnover were measured in and ex situ, as well as biomass of trees. The fungal biomass was assessed using soil ergosterol contents. The results indicate that fires slow down the turnover of soil organic matter for a period of at least 50 years. The turnover rate in recently burnt sites was only half of the turnover of the old forest site. Decreases in the turnover where still substantial 50 years after fire. The slow recovery of fungal biomass after fires seems to be the cause of the decrease since sites with a higher concentration of fungal biomass in the soils had shorter soil organic matter turnover rates. Increases in stand foliar biomass were less important for the turnover of soil organic matter. We tried to explore the potential importance of our finding using a simple data driven simulation model that estimates soil carbon dynamic from litter input and the measured soil carbon turnover times. The results indicate the initial post-fire slowdown of soil carbon turnover is an important component of the boreal carbon cycle. Using our fire intervals the simulated soil carbon stocks with a lower post-fire soil organic matter turnover were up to 15 % larger than simulations assuming a constant carbon turnover rate. Our sensitivity analysis indicates that the effects will be larger in areas with frequent fires. We do not know which environmental factors cause the delay in the turnover time and the effects of fires on post fire soil organic matter turnover could be considerably smaller or larger. Altogether our results fit well to published results from laboratory studies and show that post-fire depression of microbial activities are important on the ecosystem and landscape level. Since fire frequencies in boreal forests will increase in many areas as the result of climate change, it will be important to better understand the effects of fire on the soil carbon turnover and to incorporate it into carbon cycle models.

The influence of frontline manager job strain on burnout, commitment and turnover intention: a cross-sectional study.

PubMed

Wong, Carol A; Spence Laschinger, Heather K

2015-12-01

The frontline clinical manager role in healthcare is pivotal to the development of safe and healthy working conditions and optimal staff and patient care outcomes. However, in today's dynamic healthcare organizations managers face constant job demands from wider spans of control and complex role responsibilities but may not have adequate decisional authority to support effective work performance resulting in unnecessary job strain. Prolonged job strain can lead to burnout, health complaints, and increased turnover intention. Yet, there is limited research that examines frontline manager job strain and its impact on their well-being and work outcomes. The substantial cost associated with replacing experienced managers calls attention to the need to address job strain in order to retain this valuable organizational asset. Using Karasek's Job Demands-Control theory of job strain, a model was tested examining the effects of frontline manager job strain on their burnout (emotional exhaustion and cynicism), organizational commitment and ultimately, turnover intentions. Secondary analysis of data collected in an online cross-sectional survey of frontline managers was conducted using structural equation modeling. All 500 eligible frontline managers from 14 teaching hospitals in Ontario, Canada, were invited to participate and 159 responded for a 32% response rate. Participants received an email invitation with a secure link for the online survey. Ethics approval was obtained from the university ethics board and the respective ethics review boards of the 14 organizations involved in the study. The model was tested using path analysis techniques within structural equation modeling with maximum likelihood estimation. The final model fit the data acceptably (χ(2)=6.62, df=4, p=.16, IFI=99, CFI=.99, SRMR=.03, RMSEA=.06). Manager job strain was significantly positively associated with burnout which contributed to both lower organizational commitment and higher turnover intention. Organizational commitment was also negatively associated with turnover intention and there was an additional direct positive relationship between job strain and turnover intention. Preliminary support was found for a model showing that manager job strain contributes to burnout, reduced organizational commitment and higher turnover intentions. Findings suggest that organizations need to monitor and address manager job strain by ensuring managers' role demands are reasonable and that they have the requisite decision latitude to balance role demands. Copyright © 2015 Elsevier Ltd. All rights reserved.

Use of operating room information system data to predict the impact of reducing turnover times on staffing costs.

PubMed

Dexter, Franklin; Abouleish, Amr E; Epstein, Richard H; Whitten, Charles W; Lubarsky, David A

2003-10-01

Potential benefits to reducing turnover times are both quantitative (e.g., complete more cases and reduce staffing costs) and qualitative (e.g., improve professional satisfaction). Analyses have shown the quantitative arguments to be unsound except for reducing staffing costs. We describe a methodology by which each surgical suite can use its own numbers to calculate its individual potential reduction in staffing costs from reducing its turnover times. Calculations estimate optimal allocated operating room (OR) time (based on maximizing OR efficiency) before and after reducing the maximum and average turnover times. At four academic tertiary hospitals, reductions in average turnover times of 3 to 9 min would result in 0.8% to 1.8% reductions in staffing cost. Reductions in average turnover times of 10 to 19 min would result in 2.5% to 4.0% reductions in staffing costs. These reductions in staffing cost are achieved predominantly by reducing allocated OR time, not by reducing the hours that staff work late. Heads of anesthesiology groups often serve on OR committees that are fixated on turnover times. Rather than having to argue based on scientific studies, this methodology provides the ability to show the specific quantitative effects (small decreases in staffing costs and allocated OR time) of reducing turnover time using a surgical suite's own data. Many anesthesiologists work at hospitals where surgeons and/or operating room (OR) committees focus repeatedly on turnover time reduction. We developed a methodology by which the reductions in staffing cost as a result of turnover time reduction can be calculated for each facility using its own data. Staffing cost reductions are generally very small and would be achieved predominantly by reducing allocated OR time to the surgeons.

Metabolic labeling reveals proteome dynamics of mouse mitochondria.

PubMed

Kim, Tae-Young; Wang, Ding; Kim, Allen K; Lau, Edward; Lin, Amanda J; Liem, David A; Zhang, Jun; Zong, Nobel C; Lam, Maggie P Y; Ping, Peipei

2012-12-01

Mitochondrial dysfunction is associated with many human diseases. Mitochondrial damage is exacerbated by inadequate protein quality control and often further contributes to pathogenesis. The maintenance of mitochondrial functions requires a delicate balance of continuous protein synthesis and degradation, i.e. protein turnover. To understand mitochondrial protein dynamics in vivo, we designed a metabolic heavy water ((2)H(2)O) labeling strategy customized to examine individual protein turnover in the mitochondria in a systematic fashion. Mice were fed with (2)H(2)O at a minimal level (<5% body water) without physiological impacts. Mitochondrial proteins were analyzed from 9 mice at each of the 13 time points between 0 and 90 days (d) of labeling. A novel multiparameter fitting approach computationally determined the normalized peak areas of peptide mass isotopomers at initial and steady-state time points and permitted the protein half-life to be determined without plateau-level (2)H incorporation. We characterized the turnover rates of 458 proteins in mouse cardiac and hepatic mitochondria and found median turnover rates of 0.0402 d(-1) and 0.163 d(-1), respectively, corresponding to median half-lives of 17.2 d and 4.26 d. Mitochondria in the heart and those in the liver exhibited distinct turnover kinetics, with limited synchronization within functional clusters. We observed considerable interprotein differences in turnover rates in both organs, with half-lives spanning from hours to months (≈ 60 d). Our proteomics platform demonstrates the first large-scale analysis of mitochondrial protein turnover rates in vivo, with potential applications in translational research.

Rates of forest floor decomposition and nutrient turnover in aspen, pine, and spruce stands on two soils.

Treesearch

D. A. Perala; D.H. Alban

1982-01-01

Compares rates of forest floor decomposition and nutrient turnover in aspen and conifers. These rates were generally most rapid under aspen, slowest under spruce, and more rapid on a loamy fine sand than on a very fine sandy loam. Compares results with literature values.

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.

Determinants of turnover among low wage earners in long term care: the role of manager-employee relationships.

PubMed

Matthews, Michael; Carsten, Melissa K; Ayers, Douglas J; Menachemi, Nir

2018-02-27

The demand for Long-Term Care (LTC) is steadily increasing as Baby Boomers age and enter retirement. High turnover rates among employees in LTC creates challenges for supervisors and administrators, and can negatively impact quality of care. This study examines manager-subordinate relationship quality using Leader-Member Exchange Theory (LMX) as an antecedent to turnover among low-wage earners in the LTC environment. Survey data measuring LMX, job satisfaction, and demographic information was collected at time 1, and turnover data was collected 18 months later at time 2. The results reveal that all four LMX dimensions were rated significantly different among subordinates who left versus those who stayed, however, only the LMX dimension of supervisor loyalty was a significant predictor of turnover among low wage earners. Our study adds a more nuanced view of the reasons low-wage employees turnover, and presents implications for clinical managers and LTC organizations more broadly. Copyright © 2017 Elsevier Inc. All rights reserved.

[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.

Accumulation and turnover of carbon in organic and mineral soils of the BOREAS northern study area

USGS Publications Warehouse

Trumbore, S.E.; Harden, J.W.

1997-01-01

Rates of input, accumulation, and turnover of C differ markedly within soil profiles and in soils with different drainage in the BOREAS northern study area. Soil C storage increases from ???3 kg C m-2 in well-drained, sandy soils to greater than 100 kg C m-2 in wetlands. Two modes of C accumulation were observed in upland soil profiles. Large annual C inputs (0.06-0.1 kg C m-2 yr-1) and slow decomposition (turnover times of 6-250 years) lead to rapid C accumulation in regrowing surface moss and detrital layers following fire. Deep organic layers that have accumulated over the millennia since the initiation of soil development, and are located below the most recent charred horizon, show slower rates of input (0.015-0.03 kg C m-2 yr-1) and turnover (100-1600 years) and accumulate C about 10 times slower than surface detrital layers. Rates of C input to soils derived from C and 14C data were in accord with net primary production estimates, with highest rates of input (0.14-0.6 kg C m-2 yr-1) in wetlands. Turnover times for C in surface detrital layers were 6-15 years for well-drained sand soils that showed highest soil temperatures in summer, 30-40 years for wetlands, and 36-250 years for uplands with thick moss cover and black spruce trees. Long (>100 years) turnover times in upland black spruce/clay soils most likely reflect the influence of woody debris incorporated into detrital layers. Turnover times for deep organic and mineral layer C were controlled by drainage, with fastest turnover (80-130 years) in well-drained sand soils and slowest turnover (>3000 years) in wetlands. Total C accumulation rates, which account for C losses from both deep organic and surface detrital layers, are close to zero for sand/jack pine soils, 0.003-0.01 kg C m-2 yr-1 for moderately to poorly drained sites in mature forest stands, and 0.03 kg C m-2 yr-1 for a productive fen. Decomposition of organic matter more than several decades old accounts for 9-22% of total heterotrophic respiration at these sites. The rates of C accumulation derived here are decadal averages for specific stands and will vary as stands age or undergo disturbance. Extrapolation to larger regions and longer timescales, where burning offsets C gains in moss layers, will yield smaller rates of C storage.

Study Examines Turnover Rates in 12 Campus Jobs.

ERIC Educational Resources Information Center

Mooney, Carolyn J.

1993-01-01

A recent study investigated turnover rate and length of service in 12 college administrative positions: chief executive officer; chief academic officer; chief financial officer; registrar; admissions director; head librarian; chief student life officer; chief development officer; personnel services director; financial aid director; alumni…

Driver retention strategy : the role of a career path

DOT National Transportation Integrated Search

2000-03-01

The voluntary turnover rate among truckload carriers, at 50-100 percent, is excessive when compared to other industries. The turnover rate has been known to exceed 150 percent. It is believed that are several factors are involved in this retention pr...

Changes of Protein Turnover in Aging Caenorhabditis elegans

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

Dhondt, Ineke; Petyuk, Vladislav A.; Bauer, Sophie

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

Leaf and fine root carbon stocks and turnover are coupled across Arctic ecosystems.

PubMed

Sloan, Victoria L; Fletcher, Benjamin J; Press, Malcolm C; Williams, Mathew; Phoenix, Gareth K

2013-12-01

Estimates of vegetation carbon pools and their turnover rates are central to understanding and modelling ecosystem responses to climate change and their feedbacks to climate. In the Arctic, a region containing globally important stores of soil carbon, and where the most rapid climate change is expected over the coming century, plant communities have on average sixfold more biomass below ground than above ground, but knowledge of the root carbon pool sizes and turnover rates is limited. Here, we show that across eight plant communities, there is a significant positive relationship between leaf and fine root turnover rates (r(2) = 0.68, P < 0.05), and that the turnover rates of both leaf (r(2) = 0.63, P < 0.05) and fine root (r(2) = 0.55, P < 0.05) pools are strongly correlated with leaf area index (LAI, leaf area per unit ground area). This coupling of root and leaf dynamics supports the theory of a whole-plant economics spectrum. We also show that the size of the fine root carbon pool initially increases linearly with increasing LAI, and then levels off at LAI = 1 m(2) m(-2), suggesting a functional balance between investment in leaves and fine roots at the whole community scale. These ecological relationships not only demonstrate close links between above and below-ground plant carbon dynamics but also allow plant carbon pool sizes and their turnover rates to be predicted from the single readily quantifiable (and remotely sensed) parameter of LAI, including the possibility of estimating root data from satellites. © 2013 John Wiley & Sons Ltd.

Control of the Protein Turnover Rates in Lemna minor

PubMed Central

Trewavas, A.

1972-01-01

The control of protein turnover in Lemna minor has been examined using a method described in the previous paper for determining the rate constants of synthesis and degradation of protein. If Lemna is placed on water, there is a reduction in the rate constants of synthesis of protein and an increase (3- to 6-fold) in the rate constant of degradation. The net effect is a loss of protein from the tissue. Omission of nitrate, phosphate, sulfate, magnesium, or calcium results in increases in the rate constant of degradation of protein. An unusual dual effect of benzyladenine on the turnover constants has been observed. Treatment of Lemna grown on sucrose-mineral salts with benzyladenine results in alterations only in the rate constant of synthesis. Treatment of Lemna grown on water with benzyladenine alters only the rate constant of degradation. Abscisic acid on the other hand alters both rate constants of synthesis and degradation of protein together. Inclusion of growth-inhibiting amino acids in the medium results in a reduction in the rate constants of synthesis and increases in the rate constant of degradation of protein. It is concluded that the rate of turnover of protein in Lemna is very dependent on the composition of the growth medium. Conditions which reduce growth rates also reduce the rates of synthesis of protein and increase those of degradation. PMID:16657895

Group cohesion and nurse satisfaction: examination of a team-building approach.

PubMed

DiMeglio, Karen; Padula, Cynthia; Piatek, Carolyn; Korber, Susan; Barrett, Ann; Ducharme, Maria; Lucas, Sandra; Piermont, Nicole; Joyal, Elaine; DeNicola, Virginia; Corry, Karen

2005-03-01

The purpose of this study was to determine the impact of a team-building intervention on group cohesion, nurse satisfaction, and turnover rates. Creating an environment that supports and retains nurses represents a formidable challenge for nursing leaders. Research related to strategies that positively impact the culture in which nurses practice, thus potentially improving nurse satisfaction and reducing turnover, is critically needed. Registered nurses (RNs) employed on inpatient units in a 247-bed, private acute care Magnet teaching hospital participated in this quasi experimental preintervention and postintervention design. The RN-RN interaction subscale from the National Database of Nursing Quality Indicators Adapted Index of Work Satisfaction, the National Database of Nursing Quality Indicators Adapted Index of Job Enjoyment, the Group Cohesion Scale, and a facilitator-developed measure were completed preimplementation and postimplementation of unit-tailored intervention strategies, which took place over a 12-month period. Turnover rates were collected 6 month preintervention and postintervention. Improvement in group cohesion, RN-RN interaction, job enjoyment, and turnover was demonstrated. Targeted, unit-based strategies can be an effective means of reducing turnover rates and improving group cohesion and nurse satisfaction.

Evaluation of procedures for estimating ruminal particle turnover and diet digestibility in ruminant animals

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

Cochran, R.C.

1985-01-01

Procedures used in estimating ruminal particle turnover and diet digestibility were evaluated in a series of independent experiments. Experiment 1 and 2 evaluated the influence of sampling site, mathematical model and intraruminal mixing on estimates of ruminal particle turnover in beef steers grazing crested wheatgrass or offered ad libitum levels of prairie hay once daily, respectively. Particle turnover rate constants were estimated by intraruminal administration (via rumen cannula) of ytterbium (Yb)-labeled forage, followed by serial collection of rumen digesta or fecal samples. Rumen Yb concentrations were transformed to natural logarithms and regressed on time. Influence of sampling site (rectum versusmore » rumen) on turnover estimates was modified by the model used to fit fecal marker excretion curves in the grazing study. In contrast, estimated turnover rate constants from rumen sampling were smaller (P < 0.05) than rectally derived rate constants, regardless of fecal model used, when steers were fed once daily. In Experiment 3, in vitro residues subjected to acid or neutral detergent fiber extraction (IVADF and IVNDF), acid detergent fiber incubated in cellulase (ADFIC) and acid detergent lignin (ADL) were evaluated as internal markers for predicting diet digestibility. Both IVADF and IVNDF displayed variable accuracy for prediction of in vivo digestibility whereas ADL and ADFIC inaccurately predicted digestibility of all diets.« less

Faunal turnover in Neogene to Recent Caribbean reef corals and region environmental change

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

Budd, A.F.; Johnson, K.G.; Stemann, T.A.

1993-03-01

Quantitative analyses of species richness and species extinction and origination rates in the Neogene to Recent Caribbean reef coral fauna show that a major episode of turnover occurred during middle to late Pliocene time (4--1 Ma). The data for the authors analyses consist of a new compilation of occurrences of 175 species and 49 genera in reef sequences in the Dominican Republic and Costa Rica and in 21 scattered sites ranging in age from 22 Ma to present. The results show that: (1) during turnover, more than 75% of all species living between 6--4 Ma (n = 82) became extinct;more » (2) during turnover, extinction and origination rates were equally and simultaneously high, and a relatively constant number of species was maintained in the fauna; (3) the taxonomic composition of Caribbean reefs remained relatively constant before (10--4 Ma) and after (1--0 Ma) turnover. Turnover therefore preceded the high frequency sea level oscillations of late Pleistocene time, and appears related to long-term, unidirectional changes in climate and/or ocean circulation across the Caribbean region in association with closure of the Isthmus of Panama. The observed correspondence between high origination and extinction rates indicates that the same environmental factors may have been associated with increases in both rates, and that local habitat differentiation and fragmentation may have been involved. Stability persisted in the region despite the severe environmental stresses associated with Pleistocene climate change.« less

Seasonal variation in standardized litter decomposition and effects of elevation and land use at Mount Kilimanjaro

NASA Astrophysics Data System (ADS)

Becker, Joscha; Kuzyakov, Yakov

2017-04-01

Decomposition is one of most important ecological steps in organic matter and nutrient cycles, but studies and reliable data from tropical regions in Africa are still scarce. At the global scale, litter decomposition and recycling is controlled by climatic factors and land-use intensity. These factors can be linked to specific ecosystem characteristics along the unique elevation gradient of Mt. Kilimanjaro. Our objectives were to assess the effects of climatic conditions (i.e. elevation) and land-use intensity on C turnover and stabilization and investigated the seasonal variations. Tea-bag Index (see www.teatime4science.org) was used to measure decomposition of a standardized litter substrate by microorganisms and mesofauna <0.25 mm. Nine pairs of litterbags were exposed in eleven ecosystems for 90 days during the short-rainy (October-December), warm-dry (December-March), long-rainy (March-July) and cold-dry season (July-September) respectively. Decomposition rates increased from k=0.007 in savanna, up to a maximum of k=0.022 in cloud forest (i.e. mid elevation). The increase was followed by a decrease of 50% in (sub-) alpine ecosystems. Stabilization factors decreased from savanna (S=0.33) to coffee plantations or cloud forest (S=0.11) respectively and strongly increased again to a maximum of S=0.41 in the alpine helichrysum ecosystem. During all seasons, we found the highest decomposition rates at mid elevation. However, during both warm seasons the peak is shifted upslope. Savanna experienced the strongest seasonal variation, with 23 times higher S-values in dry- compared to rainy season. Mean annual k-values increased for about 30% with increasing land-use intensity. C stabilization in Mt. Kilimanjaro ecosystems is strongly dependent on seasonal moisture limitation (lower slope) and perennial temperature limitation (alpine zone). Ecosystems at mid elevation (around 1920 & 2120m) represent the interception zone of optimal moisture and temperature conditions. High input and fast turnover drive the C sequestration in these ecosystems, while restrains on decomposition control the C turnover in lower and higher elevation zones. Land-use intensification decreases stabilization from new C inputs in transition zones from savanna to maize monocultures and from traditional homegardens to large-scale coffee plantations.

Patterns of resident health workforce turnover and retention in remote communities of the Northern Territory of Australia, 2013-2015.

PubMed

Russell, Deborah J; Zhao, Yuejen; Guthridge, Steven; Ramjan, Mark; Jones, Michael P; Humphreys, John S; Wakerman, John

2017-08-15

The geographical maldistribution of the health workforce is a persisting global issue linked to inequitable access to health services and poorer health outcomes for rural and remote populations. In the Northern Territory (NT), anecdotal reports suggest that the primary care workforce in remote Aboriginal communities is characterised by high turnover, low stability and high use of temporary staffing; however, there is a lack of reliable information to guide workforce policy improvements. This study quantifies current turnover and retention in remote NT communities and investigates correlations between turnover and retention metrics and health service/community characteristics. This study used the NT Department of Health 2013-2015 payroll and financial datasets for resident health workforce in 53 remote primary care clinics. Main outcome measures include annual turnover rates, annual stability rates, 12-month survival probabilities and median survival. At any time point, the clinics had a median of 2.0 nurses, 0.6 Aboriginal health practitioners (AHPs), 2.2 other employees and 0.4 additional agency-employed nurses. Mean annual turnover rates for nurses and AHPs combined were extremely high, irrespective of whether turnover was defined as no longer working in any remote clinic (66%) or no longer working at a specific remote clinic (128%). Stability rates were low, and only 20% of nurses and AHPs remain working at a specific remote clinic 12 months after commencing. Half left within 4 months. Nurse and AHP turnover correlated with other workforce measures. However, there was little correlation between most workforce metrics and health service characteristics. NT Government-funded remote clinics are small, experience very high staff turnover and make considerable use of agency nurses. These staffing patterns, also found in remote settings elsewhere in Australia and globally, not only incur higher direct costs for service provision-and therefore may compromise long-term sustainability-but also are almost certainly contributing to sub-optimal continuity of care, compromised health outcomes and poorer levels of staff safety. To address these deficiencies, it is imperative that investments in implementing, adequately resourcing and evaluating staffing models which stabilise the remote primary care workforce occur as a matter of priority.

The influence of teamwork culture on physician and nurse resignation rates in hospitals.

PubMed

Mohr, David C; Burgess, James F; Young, Gary J

2008-02-01

Employee turnover is a critical concern, particularly for hospitals, because they face a very tight labour market for hiring replacements, and high turnover itself may have substantial negative effects on the continuity and quality of patient care. Hospitals with a stronger teamwork culture may experience lower turnover but this has not been formally studied. Research on determinants of employee turnover has not separated out resignations from the larger, more inclusive definition of turnover that includes retirement. This study investigated the relationship between the teamwork culture of hospitals and physician and nurse resignation rates. The study setting was the Veterans Health Administration (VHA). Each hospital was assessed on teamwork culture based on a survey of current employees. Hospital-level resignation rates were obtained for physicians and nurses. Separate multivariate regression models on physicians and nurses were employed. The models included hospital-level characteristics and labour market variables. Analysis of covariance was also performed to attempt to further reveal effects in high versus low teamwork culture hospitals. Teamwork culture was negatively associated with nurse and physician resignation rates, but was statistically significant in the nurse resignation model only. Additional analyses indicated a 0.47 standard deviation (SD) difference in nurse resignation rates and a 0.40 SD difference in physician resignation rates between hospitals in the top and bottom quartiles of the distribution for teamwork culture. In conclusion, these results suggest that developing and emphasizing a teamwork culture may facilitate greater retention of health-care employees, especially nurses.

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

Beyond safety outcomes: An investigation of the impact of safety climate on job satisfaction, employee engagement and turnover using social exchange theory as the theoretical framework.

PubMed

Huang, Yueng-Hsiang; Lee, Jin; McFadden, Anna C; Murphy, Lauren A; Robertson, Michelle M; Cheung, Janelle H; Zohar, Dov

2016-07-01

Safety climate, a measure of the degree to which safety is perceived by employees to be a priority in their company, is often implicated as a key factor in the promotion of injury-reducing behavior and safe work environments. Using social exchange theory as a theoretical basis, this study hypothesized that safety climate would be related to employees' job satisfaction, engagement, and turnover rate, highlighting the beneficial effects of safety climate beyond typical safety outcomes. Survey data were collected from 6207 truck drivers from two U.S. trucking companies. The objective turnover rate was collected one year after the survey data collection. Results showed that employees' safety climate perceptions were linked to employees' level of job satisfaction, engagement, and objective turnover rate, thus supporting the application of social exchange theory. Job satisfaction was also a significant mediator between safety climate and the two human resource outcomes (i.e., employee engagement and turnover rate). This study is among the first to assess the impact of safety climate beyond safety outcomes among lone workers (using truck drivers as an exemplar). Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Mobility-Related Teacher Turnover and the Unequal Distribution of Experienced Teachers in Turkey

ERIC Educational Resources Information Center

Özoglu, Murat

2015-01-01

This study investigates the issue of mobility-related teacher turnover in Turkey through both quantitative and qualitative methods. The quantitative findings derived from descriptive and correlational analyses of countrywide teacher-assignment and transfer data indicate that a high rate of mobility-related turnover is observed in the…

An Exploration of Turnover Experience of IT Professionals in the District of Columbia

ERIC Educational Resources Information Center

Edeh, George

2016-01-01

Turnover among information technology professionals costs organization in revenues. According to Computer Economics (2008), the cost of replacing one information technology employee is $50,000. Reports from the United States Department of Commerce and Office of Technology Policy showed that turnover rate in Information Technology has exceeded 20%…

Teachers' Perceptions of Factors That Influence Teacher Turnover

ERIC Educational Resources Information Center

McCray, Harold, Jr.

2017-01-01

Teacher turnover is a critical issue for the public education community because it influences student performance, school climate, and employee morale. In a large urban school district in the northeastern United States, the turnover rate has been high; teacher morale is low, and teacher participation in the school community is lacking. The purpose…

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…

[Nurses and doctors turnover: an impasse in the implementation of the Family Health Strategy].

PubMed

Medeiros, Cássia Regina Gotler; Junqueira, Alvaro Gustavo Wagner; Schwingel, Glademir; Carreno, Ioná; Jungles, Lúcia Adriana Pereira; Saldanha, Olinda Maria de Fátima Lechmann

2010-06-01

The research analyzed the causes for turnover rate of doctors and nurses in family health strategy teams with at least two years of implementation on March 2006 in Vale do Taquari, Rio Grande do Sul State. It is a quantitative and qualitative study identifying 31 teams in 25 towns, and the turnover rate was established by year from 1999 to 2005 by professional category. There was no turnover for doctors and nurses in 1999 and 2000. Doctor turnover was 5.9% in 2002; 32.1% in 2003; 25.8% in 2004; and 64.5% in 2005. Regarding nurses, it was 27.7% in 2001; 47% in 2002; 17.8% in 2003; 41.9% in 2004; and 22.6% in 2005. The analysis of semi-structured interviews with 7 doctors and 7 nurses appointed as main causes for turnover: poor work links, fragmented education, authoritarian way of managing, no links with the community, and poor work conditions. Thus, it is necessary to make changes regarding labor links, work conditions, and education for health workers and managers, seeking for the integrality in health practices.

A Prospective Examination of Clinician and Supervisor Turnover Within the Context of Implementation of Evidence-Based Practices in a Publicly-Funded Mental Health System.

PubMed

Beidas, Rinad S; Marcus, Steven; Wolk, Courtney Benjamin; Powell, Byron; Aarons, Gregory A; Evans, Arthur C; Hurford, Matthew O; Hadley, Trevor; Adams, Danielle R; Walsh, Lucia M; Babbar, Shaili; Barg, Frances; Mandell, David S

2016-09-01

Staff turnover rates in publicly-funded mental health settings are high. We investigated staff and organizational predictors of turnover in a sample of individuals working in an urban public mental health system that has engaged in a system-level effort to implement evidence-based practices. Additionally, we interviewed staff to understand reasons for turnover. Greater staff burnout predicted increased turnover, more openness toward new practices predicted retention, and more professional recognition predicted increased turnover. Staff reported leaving their organizations because of personal, organizational, and financial reasons; just over half of staff that left their organization stayed in the public mental health sector. Implications include an imperative to focus on turnover, with a particular emphasis on ameliorating staff burnout.

A quantitative assessment of methane cycling in Hikurangi Margin sediments (New Zealand) using geophysical imaging and biogeochemical modeling

NASA Astrophysics Data System (ADS)

Luo, Min; Dale, Andrew W.; Haffert, Laura; Haeckel, Matthias; Koch, Stephanie; Crutchley, Gareth; De Stigter, Henko; Chen, Duofu; Greinert, Jens

2016-12-01

Takahe seep, located on the Opouawe Bank, Hikurangi Margin, is characterized by a well-defined subsurface seismic chimney structure ˜80,500 m2 in area. Subseafloor geophysical data based on acoustic anomaly layers indicated the presence of gas hydrate and free gas layers within the chimney structure. Reaction-transport modeling was applied to porewater data from 11 gravity cores to constrain methane turnover rates and benthic methane fluxes in the upper 10 m. Model results show that methane dynamics were highly variable due to transport and dissolution of ascending gas. The dissolution of gas (up to 3761 mmol m-2 yr-1) dwarfed the rate of methanogenesis within the simulated sediment column (2.6 mmol m-2 yr-1). Dissolved methane is mainly consumed by anaerobic oxidation of methane (AOM) at the base of the sulfate reduction zone and trapped by methane hydrate formation below it, with maximum rates in the central part of the chimney (946 and 2420 mmol m-2 yr-1, respectively). A seep-wide methane budget was constrained by combining the biogeochemical model results with geophysical data and led to estimates of AOM rates, gas hydrate formation, and benthic dissolved methane fluxes of 3.68 × 104 mol yr-1, 73.85 × 104 mol yr-1, and 1.19 × 104 mol yr-1, respectively. A much larger flux of methane probably escapes in gaseous form through focused bubble vents. The approach of linking geochemical model results with spatial geophysical data put forward here can be applied elsewhere to improve benthic methane turnover rates from limited single spot measurements to larger spatial scales.

General practitioner turnover and migration in England 1990-94.

PubMed Central

Taylor, D H; Leese, B

1998-01-01

BACKGROUND: In tandem with fears about a GP workforce crisis, increasing attention is being focused on the supply and distribution of primary care services: on general practitioners in particular. Differential turnover and migration across health authority boundaries could lead to a maldistribution of GPs, yet comprehensive studies of GP turnover are non-existent. AIM: To quantify general practitioner (GP) turnover and migration in England from 1990 to 1994. METHOD: Yearly data from 1 October 1990 to 1 October 1994 were collected on GPs in England practising full time, including average yearly turnover, rates of entry to and exit from general practice, and net migration among GPs. All were calculated at the family health service authority (now the new health authorities) level. RESULTS: Average yearly GP turnover ranges from 2.9% in Shropshire to 7.8% in Kensington, Chelsea and Westminster; turnover is associated with deprivation and high-need areas. Migration of GPs across health authority borders was rare. Entry and exit rates were also positively related to measures of deprivation and need. Relatively underprovided health authorities lost 23 GPs over the study period as a result of migration; relatively overprovided ones gained three. CONCLUSION: Turnover is driven primarily by exits from general practice and is related to deprivation and high need. Retention appears to be the main problem in ensuring an adequate GP supply in relatively deprived and underprovided health authorities. PMID:9624750

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.

Supervisory Turnover in Outpatient Substance Abuse Treatment

PubMed Central

Knight, Danica K.; Broome, Kirk M.; Edwards, Jennifer R.; Flynn, Patrick M.

2009-01-01

Staff turnover is a significant issue within substance abuse treatment, with implications for service delivery and organizational health. This study examined factors associated with turnover among supervisors in outpatient substance abuse treatment. Turnover was conceptualized as being an individual response to organizational-level influences, and predictors represent aggregate program measures. Participants included 532 staff (including 467 counselors and 65 clinical/program directors) from 90 programs in four regions of the USA. Using logistic regression, analyses of structural factors indicated that programs affiliated with a parent organization and those providing more counseling hours to clients had higher turnover rates. When measures of job attitudes were included, only parent affiliation and collective appraisal of satisfaction were related to turnover. Subsequent analyses identified a trend toward increased supervisory turnover when satisfaction was low following the departure of a previous supervisor. These findings suggest that organizational-level factors can be influential in supervisory turnover. PMID:19949883

The effect of host structure on the selectivity and mechanism of supramolecular catalysis of Prins cyclizations

DOE PAGES

Hart-Cooper, William M.; Zhao, Chen; Triano, Rebecca M.; ...

2014-11-28

The effect of host structure on the selectivity and mechanism of intramolecular Prins reactions is evaluated using K 12Ga 4L 6 tetrahedral catalysts. The host structure was varied by modifying the structure of the chelating moieties and the size of the aromatic spacers. While variation in chelator substituents was generally observed to affect changes in rate but not selectivity, changing the host spacer afforded differences in efficiency and product diastereoselectivity. An extremely high number of turnovers (up to 840) was observed. Maximum rate accelerations were measured to be on the order of 10 5, which numbers among the largest magnitudesmore » of transition state stabilization measured with a synthetic host-catalyst. Host/guest size effects were observed to play an important role in host-mediated enantioselectivity.« less

Turnover Time in the Hyporheic Zone as Assessed by 3D Geophysical Imaging

NASA Astrophysics Data System (ADS)

Kohler, B.; Hall, R. O., Jr.; Carr, B.

2017-12-01

The hyporheic zone (HZ) is a region of interest in stream hydrology and ecology, however, its heterogeneity across small spatial scales and difficulty to directly measure has hampered researchers' efforts to understand its specific contribution to processes such as solute transport and nutrient retention and removal. In recent years researchers have combined geophysical imaging, such as electrical resistivity tomography (ERT), with tracer additions to directly measure exchange between surface waters and the HZ without physically disrupting natural subsurface flow paths. We conducted constant-rate tracer additions in two small headwater mountain streams while collecting 3D ERT images downstream before, during, after each tracer addition to yield spatially comprehensive models of solute exchange with the HZ through time. From our 3D HZ models, we calculated the active volume of the HZ, normalized to the maximum measured size, for each time step giving a breakthrough curve of tracer abundance in the HZ through time. We then described the tracer's turnover time in the HZ by applying exponential and power decay models to the breakthrough curve of HZ volume in a similar manner that one would for a tracer breakthrough curve in surface waters. Our models suggest that the flushing of solutes from the HZ exhibit multi-domain behavior, where advective and diffusive exchange between HZ and surface waters occur simultaneously and operate at distinctly different rates.

Longitudinal associations of nursing staff turnover with patient outcomes in long-term care hospitals in Korea.

PubMed

Kim, Yoonseo; Han, Kihye

2018-01-10

To describe the characteristics of long-term care hospitals in 2010-2013 and to examine the longitudinal associations of nursing staff turnover with patient outcomes. The number of long-term care hospitals has exploded in Korea since the national long-term care insurance was launched in 2008. The care quality deviation across long-term care hospitals is large. This was a longitudinal secondary data analysis using the Health Insurance Review and Assessment Service's data. From 2010 to 2013, the nursing staff turnover rate decreased. The number of patients per registered nurse increased while that per total nursing staff and skill mix decreased. All adverse patient outcomes decreased. Higher nursing staff turnover and lower RN proportions were associated with adverse patient outcomes. Since the launch of the long-term care insurance, total nursing staffing, turnover rate and patient outcomes have improved, while the skill mix has decreased. Systematic efforts to decrease nursing staff turnover should be implemented for better long-term care patient outcomes. In addition to maintaining high levels of nurse staffing and skill mix, supportive work environments and competitive wages and benefits could reduce turnover, and ultimately adverse patient outcomes. Health care policy should separate nursing staffing levels for registered nurses and certified nursing assistants. © 2018 John Wiley & Sons Ltd.

The Teacher Labour Market, Teacher Turnover and Disadvantaged Schools: New Evidence for England

ERIC Educational Resources Information Center

Allen, Rebecca; Burgess, Simon; Mayo, Jennifer

2018-01-01

We study the market for teachers in England, in particular teacher turnover. We show that there is a positive raw association between the level of school disadvantage and the turnover rate of its teachers. This association diminishes as we control for school, pupil and local teacher labour market characteristics, but is not eliminated. The…

Teacher Turnover: Examining Exit Attrition, Teaching Area Transfer, and School Migration

ERIC Educational Resources Information Center

Boe, Erling E.; Cook, Lynne H.; Sunderland, Robert J.

2008-01-01

The purposes of this research were to quantify trends in three components of teacher turnover and to investigate claims of excessive teacher turnover as the predominant source of teacher shortages. Attrition and teaching area transfer rates were comparable in special and general education and increased substantially from 1991-1992 to 2000-2001.…

Nursing Home Staff Turnover: Impact on Nursing Home Compare Quality Measures

ERIC Educational Resources Information Center

Castle, Nicholas G.; Engberg, John; Men, Aiju

2007-01-01

Purpose: We used data from a large sample of nursing homes to examine the association between staff turnover and quality. Design and Methods: The staff turnover measures came from primary data collected from 2,840 nursing homes in 2004 (representing a 71% response rate). Data collection included measures for nurse aides, licensed practical nurses,…

Effects of sex steroids on indices of protein turnover in rainbow trout (Oncorhynchus mykiss) white muscle

USDA-ARS?s Scientific Manuscript database

Effects of 17-estradiol (E2), testosterone, and 5a-dihydrotestosterone (DHT) on protein turnover and proteolytic gene expression were determined in rainbow trout (Oncorhynchus mykiss) primary myocytes and white muscle tissue. E2 reduced rates of protein synthesis and increased rates of protein degr...

A prospective examination of clinician and supervisor turnover within the context of implementation of evidence-based practices in a publicly-funded mental health system

PubMed Central

Marcus, Steven; Wolk, Courtney Benjamin; Powell, Byron; Aarons, Gregory A.; Evans, Arthur C.; Hurford, Matthew O.; Hadley, Trevor; Adams, Danielle R.; Walsh, Lucia M.; Babbar, Shaili; Barg, Frances; Mandell, David S.

2015-01-01

Staff turnover rates in publicly-funded mental health settings are high. We investigated staff and organizational predictors of turnover in a sample of individuals working in an urban public mental health system that has engaged in a system-level effort to implement evidence-based practices. Additionally, we interviewed staff to understand reasons for turnover. Greater staff burnout predicted increased turnover, more openness toward new practices predicted retention, and more professional recognition predicted increased turnover. Staff reported leaving their organizations because of personal, organizational, and financial reasons; just over half of staff that left their organization stayed in the public mental health sector. Implications include an imperative to focus on turnover, with a particular emphasis on ameliorating staff burnout. PMID:26179469

Are workers who leave a job exposed to similar physical demands as workers who develop clinically meaningful declines in low-back function?

PubMed

Ferguson, Sue A; Marras, William S; Lavender, Steven A; Splittstoesser, Riley E; Yang, Gang

2014-02-01

The objective is to quantify differences in physical exposures for those who stayed on a job (survivor) versus those who left the job (turnover). It has been suggested that high physical job demands lead to greater turnover and that turnover rates may supplement low-back disorder incidence rates in passive surveillance systems. A prospective study with 811 participants was conducted. The physical exposure of distribution center work was quantified using a moment monitor. A total of 68 quantitative physical exposure measures in three categories (load, position, and timing) were examined. Low-back health function was quantified using the lumbar motion monitor at baseline and 6-month follow-up. There were 365 turnover employees within the 6-month follow-up period and 446 "survivors" who remained on the same job, of which 126 survivors had a clinically meaningful decline in low-back functional performance (cases) and 320 survivors did not have a meaningful decline in low-back functional performance (noncases). Of the job exposure measures, 6% were significantly different between turnover and cases compared to 69% between turnover and noncases. Turnover employees had significantly greater exposure compared to noncases. Turnover employees had similar physical job exposures to workers who remained on the job and had a clinically meaningful decline in low-back functional performance. Thus, ergonomists and HR should be aware that high turnover jobs appear to have similar physical exposure as those jobs that put workers at risk for a decline in low-back functional performance.

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

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.

Association of Overcrowding and Turnover with Self-Harm in a Swiss Pre-Trial Prison.

PubMed

Baggio, Stéphanie; Gétaz, Laurent; Tran, Nguyen Toan; Peigné, Nicolas; Chacowry Pala, Komal; Golay, Diane; Heller, Patrick; Bodenmann, Patrick; Wolff, Hans

2018-03-27

Self-harm is a common issue in detention and includes both suicidal and non-suicidal behaviours. Beyond well-known individual risk factors, institutional factors such as overcrowding (i.e., when the prison population exceeds its capacity) and turnover (i.e., the rate at which the prison population is renewed), may also increase the risk of self-harm. However, these factors are understudied or previous studies reported inconsistent findings. This study investigated the association of self-harm with overcrowding and turnover in the largest pre-trial Swiss prison in Geneva. Data were collected yearly between 2011 and 2017. Measures included self-harm (all kinds of self-injuring acts requiring medical attention, including self-strangulations and self-hangings). We performed meta-regressions to analyse the relationships between self-harm and institutional factors. Self-harm events were frequent, with a prevalence estimate of 26.4%. Overcrowding and turnover were high (average occupation rate of 177% and average turnover of 73%, respectively). Overcrowding and turnover were significantly associated with self-harm (respectively b = 0.068, p < 0.001 and (b = 1.257, p < 0.001). In both cases, self-harm was higher when overcrowding and turnover increased. Overcrowding and turnover raise important human rights concerns and have damaging effects on the health of people living in detention. Identification of and care for this vulnerable population at risk of self-harm are needed and institutional factors should be addressed.

Teacher Retention in International Schools: The Key Role of School Leadership

ERIC Educational Resources Information Center

Mancuso, Steven V.; Roberts, Laura; White, George P.

2010-01-01

The purpose of this study was (1) to track teacher turnover in Near East South Asia (NESA) international schools and (2) to identify correlates of teacher turnover. We received survey responses from 22 school heads and 248 teachers in NESA schools. The average turnover rate was 17 percent from 2006 to 2009, ranging from several schools with no…

Should I Stay or Should I Go? A Comparison Study of Intention to Leave among Public Child Welfare Systems with High and Low Turnover Rates

ERIC Educational Resources Information Center

Strolin-Goltzman, Jessica

2008-01-01

This comparison study analyzes the commonalties, similarities, and differences on supervisory and organizational factors between a group of high turnover systems and a group of low turnover systems. Significant differences on organizational factors, but not on supervisory factors, emerged from the statistical analysis. Additionally, this study…

Cytochrome p450 turnover: regulation of synthesis and degradation, methods for determining rates, and implications for the prediction of drug interactions.

PubMed

Yang, Jiansong; Liao, Mingxiang; Shou, Magang; Jamei, Masoud; Yeo, Karen Rowland; Tucker, Geoffrey T; Rostami-Hodjegan, Amin

2008-06-01

In vivo enzyme levels are governed by the rates of de novo enzyme synthesis and degradation. A current lack of consensus on values of the in vivo turnover half-lives of human cytochrome P450 (CYP) enzymes places a significant limitation on the accurate prediction of changes in drug concentration-time profiles associated with interactions involving enzyme induction and mechanism (time)-based inhibition (MBI). In the case of MBI, the full extent of inhibition is also sensitive to values of enzyme turnover half-life. We review current understanding of CYP regulation, discuss the pros and cons of various in vitro and in vivo approaches used to estimate the turnover of specific CYPs and, by simulation, consider the impact of variability in estimates of CYP turnover on the prediction of enzyme induction and MBI in vivo. In the absence of consensus on values for the in vivo turnover half-lives of key CYPs, a sensitivity analysis of predictions of the pharmacokinetic effects of enzyme induction and MBI to these values should be an integral part of the modelling exercise, and the selective use of values should be avoided.

Probing the Jet Turnover Frequency Dependence on Mass and Mass Accretion Rate

NASA Astrophysics Data System (ADS)

Hammerstein, Erica; Gültekin, Kayhan; King, Ashley

2018-01-01

We have examined a sample of 15 sub-Eddington supermassive black holes (SMBHs) in a variety of galaxy classifications to further understand the proposed fundamental plane of black hole activity and scaling relations between black hole masses and their radio and X-ray luminosities. This plane describes black holes from stellar-mass to supermassive. The physics probed by these sub-Eddington systems is thought to be a radiatively inefficient, jet-dominated accretion flow. By studying black holes in this regime, we can learn important information on the disk-jet connection for accreting black holes.A key factor in studying the fundamental plane is the turnover frequency — the frequency at which emission transitions from optically thick at lower frequencies to optically thin at higher frequencies. This turnover point can be measured by observing the source in both radio and X-ray. Our project aims to test the dependence of the turnover frequency on mass and mass accretion rate.Radio observations of the sample were obtained using the Karl G. Jansky Very Large Array (VLA) in the range of 5-40 GHz across four different frequency bands in A configuration to give the highest spatial resolution to focus on the core emission. Our carefully chosen sample of SMBHs with dynamically measured masses consists of two sub-samples: those with approximately constant mass accretion rate (LX/LEdd ~ 10‑7) and those with approximately constant mass (MBH ~ 108 Msun). X-ray data were obtained from archival Chandra observations. To find the turnover frequency, we used Markov Chain Monte Carlo methods to fit two power laws to the radio data and the archival X-ray data. The intersection of the radio and X-ray fits is the turnover frequency.We present the results for both subsamples of SMBHs and their relationship between the turnover frequency and X-ray luminosity, which we take to scale with mass accretion rate, and jet power derived from both radio and X-ray properties.

The Magnitude, Destinations and Determinants of Mathematics and Science Teacher Turnover

ERIC Educational Resources Information Center

Ingersoll, Richard; May, Henry

2010-01-01

The objective of this study is to use nationally representative data to examine the rates, destinations and sources of math and science teacher turnover. There are four sets of research questions the authors address concerning the departure of mathematics and science teachers from their schools: (1) At what rates do mathematics/science teachers…

Enhancer regions show high histone H3.3 turnover that changes during differentiation

PubMed Central

Deaton, Aimee M; Gómez-Rodríguez, Mariluz; Mieczkowski, Jakub; Tolstorukov, Michael Y; Kundu, Sharmistha; Sadreyev, Ruslan I; Jansen, Lars ET; Kingston, Robert E

2016-01-01

The organization of DNA into chromatin is dynamic; nucleosomes are frequently displaced to facilitate the ability of regulatory proteins to access specific DNA elements. To gain insight into nucleosome dynamics, and to follow how dynamics change during differentiation, we used a technique called time-ChIP to quantitatively assess histone H3.3 turnover genome-wide during differentiation of mouse ESCs. We found that, without prior assumptions, high turnover could be used to identify regions involved in gene regulation. High turnover was seen at enhancers, as observed previously, with particularly high turnover at super-enhancers. In contrast, regions associated with the repressive Polycomb-Group showed low turnover in ESCs. Turnover correlated with DNA accessibility. Upon differentiation, numerous changes in H3.3 turnover rates were observed, the majority of which occurred at enhancers. Thus, time-ChIP measurement of histone turnover shows that active enhancers are unusually dynamic in ESCs and changes in highly dynamic nucleosomes predominate at enhancers during differentiation. DOI: http://dx.doi.org/10.7554/eLife.15316.001 PMID:27304074

Bird species turnover is related to changing predation risk along a vegetation gradient

USGS Publications Warehouse

LaManna, Joseph A.; Hemenway, Amy B.; Boccadori, Vanna; Martin, Thomas E.

2015-01-01

Turnover in animal species along vegetation gradients is often assumed to reflect adaptive habitat preferences that are narrower than the full gradient. Specifically, animals may decline in abundance where their reproductive success is low, and these poor-quality locations differ among species. Yet habitat use does not always appear adaptive. The crucial tests of how abundances and demographic costs of animals vary along experimentally manipulated vegetation gradients are lacking. We examined habitat use and nest predation rates for 16 bird species that exhibited turnover with shifts in deciduous and coniferous vegetation. For most bird species, decreasing abundance was associated with increasing predation rates along both natural and experimentally modified vegetation gradients. This landscape-scale approach strongly supports the idea that vegetation-mediated effects of predation are associated with animal distributions and species turnover.

Campanian to Maastrichtian pollen biostratigraphy and floral turnover rates, Colville River region, north slope of Alaska

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

Frederiksen, N.O.; Schindler, K.S.

This study is based on occurrence data for 104 angiosperm pollen taxa from 83 pollen-bearing outcrop and core samples taken along the Colville River and stratigraphically distributed from the base of the Sentinel Hill Member of the Schrader Bluff Formation to the top of the Cretaceous section. Many of the pollen taxa are highly useful for intraregional correlations because they have remarkably short stratigraphic ranges and are consistently present within these ranges. Important similarities are present between North Slope pollen assemblages and those of western Canada, Siberia, and China. The Campanian-Maastrichtian boundary is approximately marked by the range bases ofmore » Wodehouseia edmontonicola and Senipites drummhellerensis and is nearly as far south (downsection) as Sentinel Hill core test 1. Based on pollen correlations with Alberta, the marine beds at Ocean Point are probably within the middle part of the Maastrichtian, and strata north of Ocean Point that contain Aquilapollenites conatus are uppermost Maastrichtian. Thus, if the Cretaceous-Tertiary boundary in the study area is represented by an unconformity as their data suggest, the lowermost Paleocene is missing, not the uppermost Cretaceous. Maximum diversities of species of the stratigraphically significant Triprojectacites and Expressipollis groups are in the upper Campanian. Major turnovers of angiosperm taxa occurred late in the Campanian and in the Maastrichtian, but high rates of first appearances coincided with high rates of last appearances. Thus, once a fairly high overall angiosperm diversity was established in the middle(.) Campanian, the diversity remained relatively constant until at or near the end of the Maastrichtian.« less

Existence of life-time stable proteins in mature rats—Dating of proteins’ age by repeated short-term exposure to labeled amino acids throughout age

PubMed Central

Schjerling, Peter; Bornø, Andreas; Holm, Lars

2017-01-01

In vivo turnover rates of proteins covering the processes of protein synthesis and breakdown rates have been measured in many tissues and protein pools using various techniques. Connective tissue and collagen protein turnover is of specific interest since existing results are rather diverging. The aim of this study is to investigate whether we can verify the presence of protein pools within the same tissue with very distinct turnover rates over the life-span of rats with special focus on connective tissue. Male and female Lewis rats (n = 35) were injected with five different isotopically labeled amino acids tracers. The tracers were injected during fetal development (Day -10 to -2), after birth (Day 5–9), at weaning (Day 25–32) at puberty (Day 54–58) and at adulthood (Day 447–445). Subgroups of rats were euthanized three days after every injection period, at different time point between injection periods and lastly at day 472. Tissue (liver, muscle, eye lens and patellar tendon) and blood samples were collected after euthanization. The enrichment of the labeled amino acids in the tissue or blood samples was measured using GC-MS-MS. In muscle and liver we demonstrated a rapid decrease of tracer enrichments throughout the rat’s life, indicating that myofibrillar and cytoskeleton proteins have a high turnover. In contrast, the connective tissue protein in the eye lens and patellar tendon of the mature rat showed detainment of tracer enrichment injected during fetal development and first living days, indicating very slow turnover. The data support the hypothesis that some proteins synthesized during the early development and growth still exist much later in life of animals and hence has a very slow turnover rate. PMID:28957442

Growth versus metabolic tissue replacement in mouse tissues determined by stable carbon and nitrogen isotope analysis

NASA Astrophysics Data System (ADS)

Macavoy, S. E.; Jamil, T.; Macko, S. A.; Arneson, L. S.

2003-12-01

Stable isotope analysis is becoming an extensively used tool in animal ecology. The isotopes most commonly used for analysis in terrestrial systems are those of carbon and nitrogen, due to differential carbon fractionation in C3 and C4 plants, and the approximately 3‰ enrichment in 15N per trophic level. Although isotope signatures in animal tissues presumably reflect the local food web, analysis is often complicated by differential nutrient routing and fractionation by tissues, and by the possibility that large organisms are not in isotopic equilibrium with the foods available in their immediate environment. Additionally, the rate at which organisms incorporate the isotope signature of a food through both growth and metabolic tissue replacement is largely unknown. In this study we have assessed the rate of carbon and nitrogen isotopic turnover in liver, muscle and blood in mice following a diet change. By determining growth rates, we were able to determine the proportion of tissue turnover caused by growth versus that caused by metabolic tissue replacement. Growth was found to account for approximately 10% of observed tissue turnover in sexually mature mice (Mus musculus). Blood carbon was found to have the shortest half-life (16.9 days), followed by muscle (24.7 days). Liver carbon turnover was not as well described by the exponential decay equations as other tissues. However, substantial liver carbon turnover was observed by the 28th day after diet switch. Surprisingly, these tissues primarily reflect the carbon signature of the protein, rather than carbohydrate, source in their diet. The nitrogen signature in all tissues was enriched by 3 - 5‰ over their dietary protein source, depending on tissue type, and the isotopic turnover rates were comparable to those observed in carbon.

Metabolic Turnover of Synaptic Proteins: Kinetics, Interdependencies and Implications for Synaptic Maintenance

PubMed Central

Cohen, Laurie D.; Zuchman, Rina; Sorokina, Oksana; Müller, Anke; Dieterich, Daniela C.; Armstrong, J. Douglas; Ziv, Tamar; Ziv, Noam E.

2013-01-01

Chemical synapses contain multitudes of proteins, which in common with all proteins, have finite lifetimes and therefore need to be continuously replaced. Given the huge numbers of synaptic connections typical neurons form, the demand to maintain the protein contents of these connections might be expected to place considerable metabolic demands on each neuron. Moreover, synaptic proteostasis might differ according to distance from global protein synthesis sites, the availability of distributed protein synthesis facilities, trafficking rates and synaptic protein dynamics. To date, the turnover kinetics of synaptic proteins have not been studied or analyzed systematically, and thus metabolic demands or the aforementioned relationships remain largely unknown. In the current study we used dynamic Stable Isotope Labeling with Amino acids in Cell culture (SILAC), mass spectrometry (MS), Fluorescent Non–Canonical Amino acid Tagging (FUNCAT), quantitative immunohistochemistry and bioinformatics to systematically measure the metabolic half-lives of hundreds of synaptic proteins, examine how these depend on their pre/postsynaptic affiliation or their association with particular molecular complexes, and assess the metabolic load of synaptic proteostasis. We found that nearly all synaptic proteins identified here exhibited half-lifetimes in the range of 2–5 days. Unexpectedly, metabolic turnover rates were not significantly different for presynaptic and postsynaptic proteins, or for proteins for which mRNAs are consistently found in dendrites. Some functionally or structurally related proteins exhibited very similar turnover rates, indicating that their biogenesis and degradation might be coupled, a possibility further supported by bioinformatics-based analyses. The relatively low turnover rates measured here (∼0.7% of synaptic protein content per hour) are in good agreement with imaging-based studies of synaptic protein trafficking, yet indicate that the metabolic load synaptic protein turnover places on individual neurons is very substantial. PMID:23658807

Reversal in the relationship between species richness and turnover in a phytoplankton community.

PubMed

Matthews, Blake; Pomati, Francesco

2012-11-01

Negative relationships between species richness and the rate of compositional turnover are common, suggesting that diverse communities have greater stability than depauperate ones; however, the mechanistic basis for this pattern is still widely debated. Species richness and turnover can covary either because they are mechanistically linked or because they share common environmental drivers. Few empirical studies have combined long-term changes in community composition with multiple drivers of environmental change, and so little is known about how the underlying mechanisms of species coexistence interact with changes in the mean and variability of environmental conditions. Here, we use a 33 year long time series (1976-2008) of phytoplankton community composition from Lake Zurich, to examine how environmental variation influences the relationship between richness and annual turnover. We find that the relationship between richness and annual turnover reverses midway through the time series (1992-1993), leading to a hump-shaped relationship between species richness and annual turnover. Using structural equation modeling we show that annual turnover and diversity are independently associated with different drivers of environmental change. Furthermore, we find that the observed annual sequences of community assembly give rise to rates of species accumulation that are more heterogeneous through time than expected by chance, likely owing to a high proportion of species showing significant autocorrelation and to strong positive covariation in the occurrences of species.

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.

Use of General Principles in Teaching Biochemistry.

ERIC Educational Resources Information Center

Fernandez, Rolando Hernandez; Tomey, Agustin Vicedo

1991-01-01

Presents Principles of Biochemistry for use as main focus of a biochemistry course. The nine guiding ideas are the principles of continual turnover, macromolecular organization, molecular recognition, multiplicity of utilization, maximum efficiency, gradual change, interrelationship, transformational reciprocity, and information transfer. In use…

Effect of Staff Turnover on Staffing: A Closer Look at Registered Nurses, Licensed Vocational Nurses, and Certified Nursing Assistants

ERIC Educational Resources Information Center

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

2006-01-01

Purpose: 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. Design and Methods: We analyzed cross-sectional data from 1,014 Texas nursing homes. Data were from the 2002 Texas Nursing Facility Medicaid Cost…

Assessing connectivity of estuarine fishes based on stable isotope ratio analysis

NASA Astrophysics Data System (ADS)

Herzka, Sharon Z.

2005-07-01

Assessing connectivity is fundamental to understanding the population dynamics of fishes. I propose that isotopic analyses can greatly contribute to studies of connectivity in estuarine fishes due to the high diversity of isotopic signatures found among estuarine habitats and the fact that variations in isotopic composition at the base of a food web are reflected in the tissues of consumers. Isotopic analysis can be used for identifying nursery habitats and estimating their contribution to adult populations. If movement to a new habitat is accompanied by a shift to foods of distinct isotopic composition, recent immigrants and residents can be distinguished based on their isotopic ratios. Movement patterns thus can be reconstructed based on information obtained from individuals. A key consideration is the rate of isotopic turnover, which determines the length of time that an immigrant to a given habitat will be distinguishable from a longtime resident. A literature survey indicated that few studies have measured turnover rates in fishes and that these have focused on larvae and juveniles. These studies reveal that biomass gain is the primary process driving turnover rates, while metabolic turnover is either minimal or undetectable. Using a simple dilution model and biomass-specific growth rates, I estimated that young fishes with fast growth rates will reflect the isotopic composition of a new diet within days or weeks. Older or slower-growing individuals may take years or never fully equilibrate. Future studies should evaluate the factors that influence turnover rates in fishes during various stages of the life cycle and in different tissues, as well as explore the potential for combining stable isotope and otolith microstructure analyses to examine the relationship between demographic parameters, movement and connectivity.

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.

Quantifying intracellular rates of glycolytic and oxidative ATP production and consumption using extracellular flux measurements

PubMed Central

Mookerjee, Shona A.; Gerencser, Akos A.; Nicholls, David G.; Brand, Martin D.

2017-01-01

Partitioning of ATP generation between glycolysis and oxidative phosphorylation is central to cellular bioenergetics but cumbersome to measure. We describe here how rates of ATP generation by each pathway can be calculated from simultaneous measurements of extracellular acidification and oxygen consumption. We update theoretical maximum ATP yields by mitochondria and cells catabolizing different substrates. Mitochondrial P/O ratios (mol of ATP generated per mol of [O] consumed) are 2.73 for oxidation of pyruvate plus malate and 1.64 for oxidation of succinate. Complete oxidation of glucose by cells yields up to 33.45 ATP/glucose with a maximum P/O of 2.79. We introduce novel indices to quantify bioenergetic phenotypes. The glycolytic index reports the proportion of ATP production from glycolysis and identifies cells as primarily glycolytic (glycolytic index > 50%) or primarily oxidative. The Warburg effect is a chronic increase in glycolytic index, quantified by the Warburg index. Additional indices quantify the acute flexibility of ATP supply. The Crabtree index and Pasteur index quantify the responses of oxidative and glycolytic ATP production to alterations in glycolysis and oxidative reactions, respectively; the supply flexibility index quantifies overall flexibility of ATP supply; and the bioenergetic capacity quantifies the maximum rate of total ATP production. We illustrate the determination of these indices using C2C12 myoblasts. Measurement of ATP use revealed no significant preference for glycolytic or oxidative ATP by specific ATP consumers. Overall, we demonstrate how extracellular fluxes quantitatively reflect intracellular ATP turnover and cellular bioenergetics. We provide a simple spreadsheet to calculate glycolytic and oxidative ATP production rates from raw extracellular acidification and respiration data. PMID:28270511

Retaining Teachers of Color: A Pressing Problem and a Potential Strategy for "Hard-to-Staff" Schools

ERIC Educational Resources Information Center

Achinstein, Betty; Ogawa, Rodney T.; Sexton, Dena; Freitas, Casia

2010-01-01

Given calls to diversify the teaching workforce, this review examines research on retention and turnover of teachers of color, focusing on new teachers because they leave at disproportionately high rates. Reviewing 70 studies, the authors found that (a) recent national studies identify turnover rates for teachers of color are now higher than those…

Teacher Retention: A Phenomenological Investigation into the Lived Experiences of Three Elementary Teacher Stayers

ERIC Educational Resources Information Center

Sell, Corey R.

2013-01-01

Teacher stayers have remained within a profession experiencing an average annual turnover rate of 14% (Liu, 2007) and its lowest levels of job satisfaction in 20 years (MetLife Survey of the American Teacher, 2011). Exploring the lived experiences of teacher stayers might hold significant potential in decreasing the turnover rate given they have…

The Relationships Among Licensed Nurse Turnover, Retention, and Rehospitalization of Nursing Home Residents

PubMed Central

Thomas, Kali S.

2013-01-01

Purpose: Individuals receiving postacute care in skilled nursing facilities often require complex, skilled care provided by licensed nurses. It is believed that a stable set of nursing personnel is more likely to deliver better care. The purpose of this study was to determine the relationships among licensed nurse retention, turnover, and a 30-day rehospitalization rate in nursing homes (NHs). Design and Methods: We combined two data sources: NH facility-level data (including characteristics of the facility, the market, and residents) and the Florida Nursing Home Staffing Reports (which provide staffing information for each NH) for 681 Florida NHs from 2002 to 2009. Using a two-way fixed effects model, we examined the relationships among licensed nurse turnover rates, retention rates, and 30-day rehospitalization rates. Results: Results indicate that an NH’s licensed nurse retention rate is significantly associated with the 30-day rehospitalization rate (est. = −.02, p = .04) controlling for demographic characteristics of the patient population, residents’ preferences for hospitalization, and the ownership characteristics of the NH. The NHs experiencing a 10% increase in their licensed nurse retention had a 0.2% lower rehospitalization rate, which equates to 2 fewer hospitalizations per NH annually. Licensed nurse turnover is not significantly related to the 30-day rehospitalization rate. Implications: These findings highlight the need for NH administrators and policy makers to focus on licensed nurse retention, and future research should focus on the measures of staff retention for understanding the staffing/quality relationship. PMID:22936529

Measuring rural allied health workforce turnover and retention: what are the patterns, determinants and costs?

PubMed

Chisholm, Marita; Russell, Deborah; Humphreys, John

2011-04-01

To measure variations in patterns of turnover and retention, determinants of turnover, and costs of recruitment of allied health professionals in rural areas. Data were collected on health service characteristics, recruitment costs and de-identified individual-level employment entry and exit data for dietitians, occupational therapists, physiotherapists, podiatrists, psychologists, social workers and speech pathologists employed between 1 January 2004 and 31 December 2009. Health services providing allied health services within Western Victoria were stratified by geographical location and town size. Eighteen health services were sampled, 11 participated. Annual turnover rates, stability rates, median length of stay in current position, survival probabilities, turnover hazards and median costs of recruitment were calculated. Analysis of commencement and exit data from 901 allied health professionals indicated that differences in crude workforce patterns according to geographical location emerge 12 to 24 months after commencement of employment, although the results were not statistically significant. Proportional hazards modelling indicated profession and employee age and grade upon commencement were significant determinants of turnover risk. Costs of replacing allied health workers are high. An opportunity for implementing comprehensive retention strategies exists in the first year of employment in rural and remote settings. Benchmarks to guide workforce retention strategies should take account of differences in patterns of allied health turnover and retention according to geographical location. Monitoring allied health workforce turnover and retention through analysis of routinely collected data to calculate selected indicators provides a stronger evidence base to underpin workforce planning by health services and regional authorities. © 2011 The Authors. Australian Journal of Rural Health © National Rural Health Alliance Inc.

Blade life span, structural investment, and nutrient allocation in giant kelp.

PubMed

Rodriguez, Gabriel E; Reed, Daniel C; Holbrook, Sally J

2016-10-01

The turnover of plant biomass largely determines the amount of energy flowing through an ecosystem and understanding the processes that regulate turnover has been of interest to ecologists for decades. Leaf life span theory has proven useful in explaining patterns of leaf turnover in relation to resource availability, but the predictions of this theory have not been tested for macroalgae. We measured blade life span, size, thickness, nitrogen content, pigment content, and maximum photosynthetic rate (P max) in the giant kelp (Macrocystis pyrifera) along a strong resource (light) gradient to test whether the predictions of leaf life span theory applied to this alga. We found that shorter blade life spans and larger blade areas were associated with increased light availability. In addition, nitrogen and P max decreased with blade age, and their decrease was greater in shorter lived blades. These observations are generally consistent with patterns observed for higher plants and the prevailing theory of leaf life span. By contrast, variation observed in pigments of giant kelp was inconsistent with that predicted by leaf life span theory, as blades growing in the most heavily shaded portion of the forest had the lowest chlorophyll content. This result may reflect the dual role of macroalgal blades in carbon fixation and nutrient absorption and the ability of giant kelp to modify blade physiology to optimize the acquisition of light and nutrients. Thus, the marine environment may place demands on resource acquisition and allocation that have not been previously considered with respect to leaf life span optimization.

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

Determinants of fluidlike behavior and effective viscosity in cross-linked actin networks.

PubMed

Kim, Taeyoon; Gardel, Margaret L; Munro, Ed

2014-02-04

The actin cortex has a well-documented ability to rapidly remodel and flow while maintaining long-range connectivity, but how this is achieved remains poorly understood. Here, we use computer simulations to explore how stress relaxation in cross-linked actin networks subjected to extensional stress depends on the interplay between network architecture and turnover. We characterize a regime in which a network response is nonaffine and stress relaxation is governed by the continuous dissipation of elastic energy via cyclic formation, elongation, and turnover of tension-bearing elements. Within this regime, for a wide range of network parameters, we observe a constant deformation (creep) rate that is linearly proportional to the rate of filament turnover, leading to a constant effective viscosity that is inversely proportional to turnover rate. Significantly, we observe a biphasic dependence of the creep rate on applied stress: below a critical stress threshold, the creep rate increases linearly with applied stress; above that threshold, the creep rate becomes independent of applied stress. We show that this biphasic stress dependence can be understood in terms of the nonlinear force-extension behavior of individual force-transmitting network elements. These results have important implications for understanding the origins and control of viscous flows both in the cortex of living cells and in other polymer networks. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Radiocarbon dating reveals minimal collagen turnover in both healthy and osteoarthritic human cartilage.

PubMed

Heinemeier, Katja M; Schjerling, Peter; Heinemeier, Jan; Møller, Mathias B; Krogsgaard, Michael R; Grum-Schwensen, Tomas; Petersen, Michael M; Kjaer, Michael

2016-07-06

The poor regenerative capacity of articular cartilage presents a major clinical challenge and may relate to a limited turnover of the cartilage collagen matrix. However, the collagen turnover rate during life is not clear, and it is debated whether osteoarthritis (OA) can influence it. Using the carbon-14 ((14)C) bomb-pulse method, life-long replacement rates of collagen were measured in tibial plateau cartilage from 23 persons born between 1935 and1997 (15 and 8 persons with OA and healthy cartilage, respectively). The (14)C levels observed in cartilage collagen showed that, virtually, no replacement of the collagen matrix happened after skeletal maturity and that neither OA nor tissue damage, per se, influenced collagen turnover. Regional differences in (14)C content across the joint surface showed that cartilage collagen located centrally on the joint surface is formed several years earlier than collagen located peripherally. The collagen matrix of human articular cartilage is an essentially permanent structure that has no significant turnover in adults, even with the occurrence of disease. Copyright © 2016, American Association for the Advancement of Science.

RN Job Satisfaction and Retention After an Interprofessional Team Intervention.

PubMed

Baik, Dawon; Zierler, Brenda

2018-04-01

Despite continuing interest in interprofessional teamwork to improve nurse outcomes and quality of care, there is little research that focuses on nurse job satisfaction and retention after an interprofessional team intervention. This study explored registered nurse (RN) job satisfaction and retention after a purposeful interprofessional team training and structured interprofessional bedside rounds were implemented. As part of a larger study, in this comparative cross-sectional study, pre- and post-intervention data on RN job satisfaction and turnover rate were collected and analyzed. It was found that RNs had significantly higher job satisfaction after the interprofessional team intervention. The 6-month period turnover rate in the post-intervention period was slightly lower than the 6-month period turnover rate in pre-intervention period; however, the rate was too low to provide statistical evidence. Ongoing coaching and supportive work environments to improve RN outcomes should be considered to enhance quality of care and patient safety in healthcare.

The Effect of Primary Care Provider Turnover on Patient Experience of Care and Ambulatory Quality of Care.

PubMed

Reddy, Ashok; Pollack, Craig E; Asch, David A; Canamucio, Anne; Werner, Rachel M

2015-07-01

Primary care provider (PCP) turnover is common and can disrupt patient continuity of care. Little is known about the effect of PCP turnover on patient care experience and quality of care. To measure the effect of PCP turnover on patient experiences of care and ambulatory care quality. Observational, retrospective cohort study of a nationwide sample of primary care patients in the Veterans Health Administration (VHA). We included all patients enrolled in primary care at the VHA between 2010 and 2012 included in 1 of 2 national data sets used to measure our outcome variables: 326,374 patients in the Survey of Healthcare Experiences of Patients (SHEP; used to measure patient experience of care) associated with 8441 PCPs and 184,501 patients in the External Peer Review Program (EPRP; used to measure ambulatory care quality) associated with 6973 PCPs. Whether a patient experienced PCP turnover, defined as a patient whose provider (physician, nurse practitioner, or physician assistant) had left the VHA (ie, had no patient encounters for 12 months). Five patient care experience measures (from SHEP) and 11 measures of quality of ambulatory care (from EPRP). Nine percent of patients experienced a PCP turnover in our study sample. Primary care provider turnover was associated with a worse rating in each domain of patient care experience. Turnover was associated with a reduced likelihood of having a positive rating of their personal physician of 68.2% vs 74.6% (adjusted percentage point difference, -5.3; 95% CI, -6.0 to -4.7) and a reduced likelihood of getting care quickly of 36.5% vs 38.5% (adjusted percentage point difference, -1.1; 95% CI, -2.1 to -0.1). In contrast, PCP turnover was not associated with lower quality of ambulatory care except for a lower likelihood of controlling blood pressure of 78.7% vs 80.4% (adjusted percentage point difference, -1.44; 95% CI, -2.2 to -0.7). In 9 measures of ambulatory care quality, the difference between patients who experienced no PCP turnover and those who had a PCP turnover was less than 1 percentage point. These effects were moderated by the patients' continuity with their PCP prior to turnover, with a larger detrimental effect of PCP turnover among those with higher continuity prior to the turnover. Primary care provider turnover was associated with worse patient experiences of care but did not have a major effect on ambulatory care quality.

Evolution and Spectrum of the Radio Emission of Tycho's Supernova Remnant

NASA Astrophysics Data System (ADS)

Vinyaikin, E. N.

2018-02-01

The radio spectrum of Tycho's Supernova Remnant is constructed at frequencies 12.6-143 000 MHz for epoch 2010.3, taking into account the secular decrease in the radio flux density of the remnant at the rate d = -(0.46 ± 0.03)%/year: S_ν ^{3C10} (t = 2010.3) = (43.1 ± 1.8 Jy)(ν [GHz])^{ - (0.592 ± 0.019) + (0.041 ± 0.012)log (ν [GHz])} . The spectrum has positive curvature. The presence of a low-frequency turnover in the spectrum of the radio source 3C10 with its maximum at 7.7 MHz is predicted, due to absorption in the interstellar medium in the direction toward the source.

Developmental Climate: A Cross-level Analysis of Voluntary Turnover and Job Performance

PubMed Central

Spell, Hannah B.; Eby, Lillian T.; Vandenberg, Robert J.

2014-01-01

This research investigates the influence of shared perceptions of developmental climate on individual-level perceptions of organizational commitment, engagement, and perceived competence, and whether these attitudes mediate the relationship between developmental climate and both individual voluntary turnover and supervisor-rated job performance. Survey data were collected from 361 intact employee-supervisory mentoring dyads and matched with employee turnover data collected one year later to test the proposed framework using multilevel modeling techniques. As expected, shared perceptions of developmental climate were significantly and positively related to all three individual work attitudes. In addition, both organizational commitment and perceived competence were significant mediators of the positive relationship between shared perceptions of developmental climate and voluntary turnover, as well as shared perceptions of developmental climate and supervisor-rated job performance. By contrast, no significant mediating effects were found for engagement. Theoretical implications, limitations, and future research are discussed. PMID:24748681

Estimating soil turnover rate from tree uprooting during hurricanes in Puerto Rico

USGS Publications Warehouse

Lenart, M.T.; Falk, D.A.; Scatena, F.N.; Osterkamp, W.R.

2010-01-01

Soil turnover by tree uprooting in primary and secondary forests on the island of Puerto Rico was measured in 42 study plots in the months immediately after the passage of a Category 3 hurricane. Trunk basal area explained 61% of the variability of mound volume and 53% of the variability of mound area. The proportion of uprooted trees, the number of uprooted trees, or the proportion of uprooted basal area explained 84-85% of the variation in hurricane-created mound area. These same variables explain 79-85% of the variation in mound volume. The study indicates that the soil turnover period from tree uprooting by Puerto Rican hurricanes is between 1600 and 4800 years. These rates are faster than soil turnover by landslides and background treefall in the same area and provide a useful age constraint on soil profile development and soil carbon sequestration in these dynamic landscapes. ?? 2009 Elsevier B.V.

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.

A blueprint for reducing turnover among nursing assistants: a Louisiana study.

PubMed

Parsons, S; Parker, K P; Ghose, R P

1998-11-01

For decades, various exposes and reports have painted an unflattering portrait of the nursing home industry across the nation. Nursing homes in Louisiana have endured their fair share of publicity and criticism. The industry in this state has been accused of being preoccupied with profits rather than quality resident care. And, while there is much debate as to the validity of this complaint, there is solid agreement that competent and stable nursing assistants are the key to quality resident care. Unfortunately, the annual turnover rate of these essential employees ranges from 50% to 400%, nationally. This research identified the factors most responsible for the rate of turnover of nursing assistants employed in Louisiana nursing homes. Based upon the results of this study, pay, benefits, workload, and employee-employer relations, are not related to turnover. The analysis revealed that only three issues are associated with turnover--the number of beds, the number of beds per registered nurse, and the number of beds per social service worker. The message is clear: nursing home administrators must be very careful in stretching such resources. The number of beds assigned to an RN, and, in particular, the number of beds per social service worker are management issues that, if overextended, risk the turnover of nursing assistants.

Protein turnover measurement using selected reaction monitoring-mass spectrometry (SRM-MS)

PubMed Central

Holman, Stephen W.; Hammond, Dean E.; Simpson, Deborah M.; Waters, John; Hurst, Jane L.

2016-01-01

Protein turnover represents an important mechanism in the functioning of cells, with deregulated synthesis and degradation of proteins implicated in many diseased states. Therefore, proteomics strategies to measure turnover rates with high confidence are of vital importance to understanding many biological processes. In this study, the more widely used approach of non-targeted precursor ion signal intensity (MS1) quantification is compared with selected reaction monitoring (SRM), a data acquisition strategy that records data for specific peptides, to determine if improved quantitative data would be obtained using a targeted quantification approach. Using mouse liver as a model system, turnover measurement of four tricarboxylic acid cycle proteins was performed using both MS1 and SRM quantification strategies. SRM outperformed MS1 in terms of sensitivity and selectivity of measurement, allowing more confident determination of protein turnover rates. SRM data are acquired using cheaper and more widely available tandem quadrupole mass spectrometers, making the approach accessible to a larger number of researchers than MS1 quantification, which is best performed on high mass resolution instruments. SRM acquisition is ideally suited to focused studies where the turnover of tens of proteins is measured, making it applicable in determining the dynamics of proteins complexes and complete metabolic pathways. This article is part of the themed issue ‘Quantitative mass spectrometry’. PMID:27644981

Effects of role stress on nurses' turnover intentions: The mediating effects of organizational commitment and burnout.

PubMed

Han, Sang-Sook; Han, Jeong-Won; An, Young-Suk; Lim, So-Hee

2015-10-01

This paper was designed to extend the extant research regarding factors related to nurses' turnover intentions. This survey-based study was based on a path analysis designed to verify a hypothesized causal model involving nurses' role stress, organizational commitment, turnover intentions, and burnout. This study distributed 500 questionnaires to nurses in general hospitals with more than 500 beds located in Seoul, Korea, during 16-30 April 2012. Role conflict, an underlying factor in role stress, had no significant effect on role stress, but the results showed that role ambiguity reduced organizational commitment. On the other hand, role conflict and role ambiguity increased the level of burnout. Organizational commitment reduced turnover intentions, and burnout increased turnover intentions. Role conflict and role ambiguity had no direct effect on turnover intentions, but they had indirect effects on organizational commitment and burnout. To reduce nurses' turnover rate, this study recommends developing plans to improve their organizational commitment because it mediates role stress and turnover intention. © 2014 The Authors. Japan Journal of Nursing Science © 2014 Japan Academy of Nursing Science.

Does Enhancing Work-Time Control and Flexibility Reduce Turnover? A Naturally Occurring Experiment.

PubMed

Moen, Phyllis; Kelly, Erin L; Hill, Rachelle

2011-02-01

We investigate the turnover effects of an organizational innovation (ROWE-Results Only Work Environment) aimed at moving away from standard time practices to focus on results rather than time spent at work. To model rates of turnover, we draw on survey data from a sample of employees at a corporate headquarters (N = 775) and institutional records of turnover over eight months following the ROWE implementation. We find the odds of turnover are indeed lower for employees participating in the ROWE initiative, which offers employees greater work-time control and flexibility, and that this is the case regardless of employees' gender, age, or family life stage. ROWE also moderates the turnover effects of organizational tenure and negative home-to-work spillover, physical symptoms, and job insecurity, with those in ROWE who report these situations generally less likely to leave the organization. Additionally, ROWE reduces turnover intentions among those remaining with the corporation. This research moves the "opting-out" argument from one of private troubles to an issue of greater employee work-time control and flexibility by showing that an organizational policy initiative can reduce turnover.

Greater soil carbon stocks and faster turnover rates with increasing agricultural productivity

NASA Astrophysics Data System (ADS)

Sanderman, Jonathan; Creamer, Courtney; Baisden, W. Troy; Farrell, Mark; Fallon, Stewart

2017-01-01

Devising agricultural management schemes that enhance food security and soil carbon levels is a high priority for many nations. However, the coupling between agricultural productivity, soil carbon stocks and organic matter turnover rates is still unclear. Archived soil samples from four decades of a long-term crop rotation trial were analyzed for soil organic matter (SOM) cycling-relevant properties: C and N content, bulk composition by nuclear magnetic resonance (NMR) spectroscopy, amino sugar content, short-term C bioavailability assays, and long-term C turnover rates by modeling the incorporation of the bomb spike in atmospheric 14C into the soil. After > 40 years under consistent management, topsoil carbon stocks ranged from 14 to 33 Mg C ha-1 and were linearly related to the mean productivity of each treatment. Measurements of SOM composition demonstrated increasing amounts of plant- and microbially derived SOM along the productivity gradient. Under two modeling scenarios, radiocarbon data indicated overall SOM turnover time decreased from 40 to 13 years with increasing productivity - twice the rate of decline predicted from simple steady-state models or static three-pool decay rates of measured C pool distributions. Similarly, the half-life of synthetic root exudates decreased from 30.4 to 21.5 h with increasing productivity, indicating accelerated microbial activity. These findings suggest that there is a direct feedback between accelerated biological activity, carbon cycling rates and rates of carbon stabilization with important implications for how SOM dynamics are represented in models.

In vivo neutron activation analysis of sodium and chlorine in tumor tissue after fast neutron therapy.

PubMed

Auberger, T; Koester, L; Knopf, K; Weissfloch, L

1996-01-01

In 12 patients with recurrences and metastases of different primaries (head and neck cancer, breast cancer, malignant melanoma, and osteosarcoma) who were treated with reactor fission neutrons the photon emission of irradiated tissue was measured after each radiotherapy fraction. Spectral analyses of the decay rates resulted in data for the exchange of sodium (Na) and chlorine (Cl) between the irradiated tissue and the body. About 60% of Na and Cl exchanged rapidly with a turnover half-life of 13 +/- 2 min. New defined mass exchange rates for Na and Cl amount to an average of 0.8 mval/min/kg of soft tissue. At the beginning of radiotherapy the turnover of the electrolytes in tissues with large tumor volumes was about twice that in tissues with small tumor volumes. Depending on the dose, neutron therapy led in all cases to variation in the metabolism. A maximum of Cl exchange and a minimum of Na exchange occurred after 10 Gy of neutrons (group of six previously untreated patients) or after 85 Gy (photon equivalent dose) of combined photon-neutron therapy. A significant increase in non-exchangeable fraction of Na from about 40 to 80% was observed in three tumors after a neutron dose of 10 Gy administered in five fractions correlated with a rapid reduction of tissue within 4 weeks after end of therapy. These results demonstrate for the first time the local response of the electrolyte metabolism to radiotherapy.

Antibody Drug Conjugates: Application of Quantitative Pharmacology in Modality Design and Target Selection.

PubMed

Sadekar, S; Figueroa, I; Tabrizi, M

2015-07-01

Antibody drug conjugates (ADCs) are a multi-component modality comprising of an antibody targeting a cell-specific antigen, a potent drug/payload, and a linker that can be processed within cellular compartments to release payload upon internalization. Numerous ADCs are being evaluated in both research and clinical settings within the academic and pharmaceutical industry due to their ability to selectively deliver potent payloads. Hence, there is a clear need to incorporate quantitative approaches during early stages of drug development for effective modality design and target selection. In this review, we describe a quantitative approach and framework for evaluation of the interplay between drug- and systems-dependent properties (i.e., target expression, density, localization, turnover, and affinity) in order to deliver a sufficient amount of a potent payload into the relevant target cells. As discussed, theoretical approaches with particular considerations given to various key properties for the target and modality suggest that delivery of the payload into particular effect cells to be more sensitive to antigen concentrations for targets with slow turnover rates as compared to those with faster internalization rates. Further assessments also suggest that increasing doses beyond the threshold of the target capacity (a function of target internalization and expression) may not impact the maximum amount of payload delivered to the intended effect cells. This article will explore the important application of quantitative sciences in selection of the target and design of ADC modalities.

The role of Callianassa subterranea (Montagu) (THALASSINIDEA) in sediment resuspension in the North Sea

NASA Astrophysics Data System (ADS)

Rowden, A. A.; Jones, M. B.; Morris, A. W.

1998-09-01

The mud shrimp Callianassa subterranea (Montagu) is a common member of the macrobenthic community at the site in the North Sea selected to study the dynamics of suspended sediment behaviour. The extensive burrowing habit of this deposit-feeding species makes it an important contributor to the degree of bioturbation experienced at the site. Individuals recovered from the site were returned to the laboratory to investigate the influence of body size and temperature upon the amount of sediment expelled. A clear relationship between these variables and the quantity of expelled sediment was identified, and a well-defined temporal pattern of expulsion activity and inactivity was demonstrated. These experimental data, together with field information on seawater temperatures and aspects of mud shrimp population dynamics, allow the construction of an estimated annual sediment turnover budget of 11 kg (dry weight) m -2 yr -1. Field observations at the North Sea site show that the sediment expelled by the mud shrimp forms unconsolidated volcano-like mounds, which significantly modify seabed surface topography. The dimensions of these surface features were measured from bottom photographs of the site and used to determine values of boundary roughness length ( Zo). In January Zo was 0.0007 cm, whilst in September Zo equaled 0.79 cm. Callianassa subterranea's maximum contribution to resuspension was assessed by calculating a derived lateral sediment transport rate of 7 kg m -1 month -1 (from values of near-bed current velocity, modified boundary roughness length and sediment turnover rate).

Competency-Based Training and Worker Turnover in Community Supports for People With IDD: Results From a Group Randomized Controlled Study.

PubMed

Bogenschutz, Matthew; Nord, Derek; Hewitt, Amy

2015-06-01

Turnover among direct support professionals (DSPs) in community support settings for individuals with intellectual and developmental disabilities (IDD) has been regarded as a challenge since tracking of this workforce began in the 1980s. This study utilized a group randomized controlled design to test the effects of a competency-based training intervention for DSPs on site-level turnover rates over a one year period. Results suggested that, compared with the control group, sites receiving the training intervention experienced a significant decrease in annual turnover, when multiple factors were controlled. Implications, including the importance of considering quality training as a long term organizational investment and intervention to reduce turnover, are discussed.

Willing to walk: a creative strategy to minimize stress related to floating.

PubMed

Good, Eileen; Bishop, Paula

2011-05-01

Asking a nurse to float has traditionally been fraught with anxiety, fear, and frustration. Floating can result in nursing dissatisfaction and high turnover rates. The authors discuss a strategy to minimize nurse anxiety and enhance nurse autonomy. The strategy has been successful for more than 6 years and contributed to a positive trend in nursing satisfaction with a very low turnover rate.

Superintendent Turnover in Texas, Connecticut, Kentucky, and Oregon Public School Districts: Contributing Factors and Trends

ERIC Educational Resources Information Center

Berryhill, Kathy S.

2009-01-01

School district administrator openings are occurring across Texas and many other states at an increasing rate. The high rate of turnover in the superintendency has become a national problem. Texas was chosen for the study due to the total number of school districts in the state and the high percent of rural districts. The other selected states,…

USSR Report International Affairs.

DTIC Science & Technology

1986-09-02

minimum interest rate (price of a loan), proportion of the value of a contract to be covered by an easy loan (minimum size of payments in cash...Kuwait Laos Lebanon Malaysia Mongolian People’s Republic Nepal Pakistan Saudi Arabia Singapore Syria Turnover Export Import Turnover...including the blockade imposed on export financing. The latter was started in July 1980 by swiftly increasing the interest rates on foreign trade loans

Is Maximum Food Intake in Endotherms Constrained by Net or Factorial Aerobic Scope? Lessons from the Leaf-Eared Mouse.

PubMed

Maldonado, Karin; Sabat, Pablo; Piriz, Gabriela; Bogdanovich, José M; Nespolo, Roberto F; Bozinovic, Francisco

2016-01-01

Food availability varies substantially throughout animals' lifespans, thus the ability to profit from high food levels may directly influence animal fitness. Studies exploring the link between basal metabolic rate (BMR), growth, reproduction, and other fitness traits have shown varying relationships in terms of both magnitude and direction. The diversity of results has led to the hypothesis that these relationships are modulated by environmental conditions (e.g., food availability), suggesting that the fitness consequences of a given BMR may be context-dependent. In turn, there is indirect evidence that individuals with an increased capacity for aerobic work also have a high capacity for acquiring energy from food. Surprisingly, very few studies have explored the correlation between maximum rates of energy acquisition and BMR in endotherms, and to the best of our knowledge, none have attempted to elucidate relationships between the former and aerobic capacity [e.g., maximum metabolic rate (MMR), aerobic scope (Factorial aerobic scope, FAS; Net aerobic scope, NAS)]. In this study, we measured BMR, MMR, maximum food intake (recorded under low ambient temperature and ad libitum food conditions; MFI), and estimated aerobic scope in the leaf-eared mouse ( Phyllotis darwini ). We, then, examined correlations among these variables to determine whether metabolic rates and aerobic scope are functionally correlated, and whether an increased aerobic capacity is related to a higher MFI. We found that aerobic capacity measured as NAS is positively correlated with MFI in endotherms, but with neither FAS nor BMR. Therefore, it appears plausible that the capacity for assimilating energy under conditions of abundant resources is determined adaptively by NAS, as animals with higher NAS would be promoted by selection. In theory, FAS is an invariant measurement of the extreme capacity for energy turnover in relation to resting expenditure, whereas NAS represents the maximum capacity for simultaneous aerobic processes above maintenance levels. Accordingly, in our study, FAS and NAS represent different biological variables; FAS, in contrast to NAS, may not constrain food intake. The explanations for these differences are discussed in biological and mathematical terms; further, we encourage the use of NAS rather than FAS when analyzing the aerobic capacity of animals.

Using Absenteeism and Performance To Predict Employee Turnover: Early Detection through Company Records.

ERIC Educational Resources Information Center

Morrow, Paula C.; McElroy, James C.; Laczniak, Kathleen S.; Fenton, James B.

1999-01-01

Results of a comparison of 113 insurance company employees who left voluntarily with 113 who stayed supported a relationship between absenteeism, performance ratings, and voluntary turnover. There was no significant interaction effect. (SK)

Staff nurse turnover costs: Part II, Measurements and results.

PubMed

Jones, C B

1990-05-01

This study demonstrated that the costs of nursing turnover can be high (over +10,000 per RN turnover), and that the potential for adverse impact on the nursing department, the hospital environment, and the healthcare environment exists. The results of this study are important, particularly in the midst of a national nursing shortage, for several reasons. CNEs are responsible for obtaining, allocating, and managing nursing department resources; knowledge of nursing turnover costs will allow them to make more informed decisions about how best to allocate scarce resources. The findings of this study are also important to hospital administrators because they demonstrate the financial impact of high rates of nursing turnover on healthcare delivery. Finally, these findings provide nurse researchers direction for future research into the costs and benefits of nursing turnover and retention activities, so that cost-effective methods of minimizing organizational costs can be determined.

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.

Effects of work environment and job characteristics on the turnover intention of experienced nurses: The mediating role of work engagement.

PubMed

Wan, Qiaoqin; Li, Zhaoyang; Zhou, Weijiao; Shang, Shaomei

2018-06-01

To assess turnover intention among experienced nurses and explore the effects of work environment, job characteristics and work engagement on turnover intention. The nursing shortage is an urgent concern in China. A high turnover rate of experienced nurses could have serious effects on the quality of care, costs and the efficiency of hospitals. It is crucial to explore the predictors of turnover intention and develop strategies tailored to experienced nurses. A descriptive, cross-sectional survey design. A total of 778 experienced nurses from seven hospitals was surveyed on their work engagement, job characteristics, work environment and turnover intention in March-May 2017. Structural equation modelling was used to test a theoretical model and the hypotheses. The results showed that 35.9% of experienced nurses had high-level turnover intention. The final model explained 50% of the variance in experienced nurses' turnover intention and demonstrated that: (1) work environment was positively associated with higher work engagement and lower turnover intention and work engagement partially mediated the relationship between work environment and turnover intention; and (2) job characteristics were positively related to higher work engagement and lower turnover intention and work engagement fully mediated the relationship between job characteristics and turnover intention. The study confirms the intrinsic and extrinsic motivators on work engagement posited by job demands-resources model. Theory-driven strategies to improve work environment, enhance job characteristics and promote wok engagement are needed to address the nursing shortage and high turnover intention among experienced nurses. © 2018 John Wiley & Sons Ltd.

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.

Microbial carbon turnover in the plant-rhizosphere-soil continuum

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Carbon stock and carbon turnover in boreal and temperate forests - Integration of remote sensing data and global vegetation models

NASA Astrophysics Data System (ADS)

Thurner, Martin; Beer, Christian; Carvalhais, Nuno; Forkel, Matthias; Tito Rademacher, Tim; Santoro, Maurizio; Tum, Markus; Schmullius, Christiane

2016-04-01

Long-term vegetation dynamics are one of the key uncertainties of the carbon cycle. There are large differences in simulated vegetation carbon stocks and fluxes including productivity, respiration and carbon turnover between global vegetation models. Especially the implementation of climate-related mortality processes, for instance drought, fire, frost or insect effects, is often lacking or insufficient in current models and their importance at global scale is highly uncertain. These shortcomings have been due to the lack of spatially extensive information on vegetation carbon stocks, which cannot be provided by inventory data alone. Instead, we recently have been able to estimate northern boreal and temperate forest carbon stocks based on radar remote sensing data. Our spatially explicit product (0.01° resolution) shows strong agreement to inventory-based estimates at a regional scale and allows for a spatial evaluation of carbon stocks and dynamics simulated by global vegetation models. By combining this state-of-the-art biomass product and NPP datasets originating from remote sensing, we are able to study the relation between carbon turnover rate and a set of climate indices in northern boreal and temperate forests along spatial gradients. We observe an increasing turnover rate with colder winter temperatures and longer winters in boreal forests, suggesting frost damage and the trade-off between frost adaptation and growth being important mortality processes in this ecosystem. In contrast, turnover rate increases with climatic conditions favouring drought and insect outbreaks in temperate forests. Investigated global vegetation models from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT, are able to reproduce observation-based spatial climate - turnover rate relationships only to a limited extent. While most of the models compare relatively well in terms of NPP, simulated vegetation carbon stocks are severely biased compared to our biomass dataset. Current limitations lead to considerable uncertainties in the estimated vegetation carbon turnover, contributing substantially to the forest feedback to climate change. Our results are the basis for improving mortality concepts in models and estimating their impact on the land carbon balance.

Altered bone turnover during spaceflight

NASA Technical Reports Server (NTRS)

Turner, R. T.; Morey, E. R.; Liu, C.; Baylink, D. J.

1982-01-01

Modifications in calcium metabolism during spaceflight were studied, using parameters that reflect bone turnover. Bone formation rate, medullary area, bone length, bone density, pore size distribution, and differential bone cell number were evaluated in growing rate both immediately after and 25 days after orbital spaceflights aboard the Soviet biological satellites Cosmos 782 and 936. The primary effect of space flight on bone turnover was a reversible inhibition of bone formation at the periosteal surface. A simultaneous increase in the length of the periosteal arrest line suggests that bone formation ceased along corresponding portions of that surface. Possible reasons include increased secretion of glucocorticoids and mechanical unloading of the skeleton due to near-weightlessness, while starvation and immobilization are excluded as causes.

Proterozoic and early Cambrian protists: evidence for accelerating evolutionary tempo.

PubMed Central

Knoll, A H

1994-01-01

In rocks of late Paleoproterozoic and Mesoproterozoic age (ca. 1700-1000 million years ago), probable eukaryotic microfossils are widespread and well preserved, but assemblage and global diversities are low and turnover is slow. Near the Mesoproterozoic-Neoproterozoic boundary (1000 million years ago), red, green, and chromophytic algae diversified; molecular phylogenies suggest that this was part of a broader radiation of "higher" eukaryotic phyla. Observed diversity levels for protistan microfossils increased significantly at this time, as did turnover rates. Coincident with the Cambrian radiation of marine invertebrates, protistan microfossils again doubled in diversity and rates of turnover increased by an order of magnitude. Evidently, the Cambrian diversification of animals strongly influenced evolutionary rates, within clades already present in marine communities, implying an important role for ecology in fueling a Cambrian explosion that extends across kingdoms. Images PMID:8041692

Proterozoic and early Cambrian protists: evidence for accelerating evolutionary tempo

NASA Technical Reports Server (NTRS)

Knoll, A. H.

1994-01-01

In rocks of late Paleoproterozoic and Mesoproterozoic age (ca. 1700-1000 million years ago), probable eukaryotic microfossils are widespread and well preserved, but assemblage and global diversities are low and turnover is slow. Near the Mesoproterozoic-Neoproterozoic boundary (1000 million years ago), red, green, and chromophytic algae diversified; molecular phylogenies suggest that this was part of a broader radiation of "higher" eukaryotic phyla. Observed diversity levels for protistan microfossils increased significantly at this time, as did turnover rates. Coincident with the Cambrian radiation of marine invertebrates, protistan microfossils again doubled in diversity and rates of turnover increased by an order of magnitude. Evidently, the Cambrian diversification of animals strongly influenced evolutionary rates, within clades already present in marine communities, implying an important role for ecology in fueling a Cambrian explosion that extends across kingdoms.

Lynx1 Limits Dendritic Spine Turnover in the Adult Visual Cortex

PubMed Central

Sajo, Mari

2016-01-01

Dendritic spine turnover becomes limited in the adult cerebral cortex. Identification of specific aspects of spine dynamics that can be unmasked in adulthood and its regulatory molecular mechanisms could provide novel therapeutic targets for inducing plasticity at both the functional and structural levels for robust recovery from brain disorders and injuries in adults. Lynx1, an endogenous inhibitor of nicotinic acetylcholine receptors, was previously shown to increase its expression in adulthood and thus to limit functional ocular dominance plasticity in adult primary visual cortex (V1). However, the role of this “brake” on spine dynamics is not known. We examined the contribution of Lynx1 on dendritic spine turnover before and after monocular deprivation (MD) in adult V1 with chronic in vivo imaging using two-photon microscopy and determined the spine turnover rate of apical dendrites of layer 5 (L5) and L2/3 pyramidal neurons in adult V1 of Lynx1 knock-out (KO) mice. We found that the deletion of Lynx1 doubled the baseline spine turnover rate, suggesting that the spine dynamics in the adult cortex is actively limited by the presence of Lynx1. After MD, adult Lynx1-KO mice selectively exhibit higher rate of spine loss with no difference in gain rate in L5 neurons compared with control wild-type counterparts, revealing a key signature of spine dynamics associated with robust functional plasticity in adult V1. Overall, Lynx1 could be a promising therapeutic target to induce not only functional, but also structural plasticity at the level of spine dynamics in the adult brain. SIGNIFICANCE STATEMENT Dendritic spine turnover becomes limited in the adult cortex. In mouse visual cortex, a premier model of experience-dependent plasticity, we found that the deletion of Lynx1, a nicotinic “brake” for functional plasticity, doubled the baseline spine turnover in adulthood, suggesting that the spine dynamics in the adult cortex is actively limited by Lynx1. After visual deprivation, spine loss, but not gain rate, remains higher in adult Lynx1 knock-out mice than in control wild-type mice, revealing a key signature of spine dynamics associated with robust functional plasticity. Lynx1 would be a promising target to induce not only functional, but also structural plasticity at the level of spine dynamics in adulthood. PMID:27605620

Stayers, Leavers, and Switchers Among Certified Nursing Assistants in Nursing Homes: A Longitudinal Investigation of Turnover Intent, Staff Retention, and Turnover

PubMed Central

Rosen, Jules

2011-01-01

Purpose: 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. Design and Methods: 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. Results: 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. Implications: 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. PMID:21498629

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,...

[Impact of nurse, nurses' aid staffing and turnover rate on inpatient health outcomes in long term care hospitals].

PubMed

Kim, Yunmi; Lee, Ji Yun; Kang, Hyuncheol

2014-02-01

This study was conducted to explore the impact of registered nurse/nurses' aid (RN/NA) staffing and turnover rate on inpatient health outcomes in long term care hospitals. A secondary analysis was done of national data from the Health Insurance Review and Assessment Services including evaluation of long term care hospitals in October-December 2010 and hospital general characteristics in July-September 2010. Final analysis of data from 610 hospitals included RN/NA staffing, turnover rate of nursing staff and 5 patient health outcome indicators. Finding showed that, when variables of organization and community level were controlled, patients per RN was a significant indicator of decline in ADL for patients with dementia, and new pressure ulcer development in the high risk group and worsening of pressure ulcers. Patients per NA was a significant indicator for new pressure ulcer development in the low risk group. Turnover rate was not significant for any variable. To maintain and improve patient health outcomes of ADL and pressure ulcers, policies should be developed to increase the staffing level of RN. Studies are also needed to examine causal relation of NA staffing level, RN staffing level and patient health outcomes with consideration of the details of nursing practice.

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

Temporal variation of biomass and productivity of Thalassia testudinum (Hydrocharitaceae) in Venezuela, Southern Caribbean.

PubMed

Pérez, Daisy; Guevara, Marcel; Bone, David

2006-06-01

Annual biomass and productivity of Thalassia testudinum were determined during a year at a seagrass bed located in the Parque Nacional Morrocoy, Venezuela. Leaf, rhizome and root biomass were determined monthly, together with short-shoot density, from February 1992 to January 1993, from nine replicated core samples. Productivity was measured using the methodology by Zieman (1974) with minor modifications, and leaf turnover rate was calculated. Leaf biomass values ranged between 101.73 dry g m(-2) in February and 178.11 dry g m(-2) in August. Productivity ranged from 1.69 dry g m(-2) d(-1) in April and October to 3.30 dry g m(-2) d(-1) in July, showing two annual peaks: one in July and one in March. The leaf turnover rate showed the highest value in June (2.41% d(-1)) and the lowest in May (1.23% d(-1)). Sampling time differences in leaf biomass, productivity and turnover rate were statistically significant. Short-shoot density values varied between 811.10 shoots m(-2) in April and 1226.08 shoots m(-2) in December, but the differences were not significant along the year. These results indicated seasonal trends for leaf biomass, productivity and turnover rate of T. testudinum in the Southern Caribbean (latitude 10 degrees N).

Turnover intention among hospital-based registered nurses in the Eastern Caribbean.

PubMed

Lansiquot, Beverley Anne; Tullai-McGuinness, Susan; Madigan, Elizabeth

2012-06-01

Vacancy rates for nurses in the English-speaking Caribbean are estimated at 30% with turnover typically associated with migration. The purpose of this study was to describe the characteristics of hospital-based registered nurses (RNs) in the sub-region, their practice environment and turnover intention in two and five years, respectively, and to determine the relationships among practice environment characteristics and turnover intention. A descriptive correlational design was used with self-reported questionnaires from a convenience sample of 301 RNs working in hospitals in four English speaking Eastern Caribbean countries. Single-item visual analog scales (VAS) were used to measure turnover intention in 2 years and 5 years. The Practice Environment Scale of the Nursing Work Index (PES-NWI) measured the characteristics in the practice environment. The mean age of the nurses was 32.5 (SD = 6.75) years. Most nurses (58.8%) were single and 91.4% had relatives living abroad. Nurses scored three PES-NWI subscales < 2.5, indicating a less positive practice environment: resource adequacy, nurse participation in hospital affairs, and nurse managers' ability, leadership, and support. The subscale for collegial nurse-physician relations received the best rating (mean = 2.61, SD = .62). For 2-year intention to leave, the mean rating on the 100-mm VAS was 63.2, while that for the 5-year intention to leave was 65.6. No significant correlations were found among four of the five PES-NWI subscales and turnover intention in 2 and 5 years. The practice environment, while generally unfavorable, is not associated with the nurses' intention to leave their jobs. These findings support the current policy position that calls for managing turnover among nurses. Nursing and health system administrators should assess, plan, and implement workforce policies to slow the outflow of nurses. Initiatives to improve the work environment and the delivery of high-quality care are important to RNs in the Eastern Caribbean. Managing the negative impact of continuous outflow of nurses through turnover requires long-term coordinated policy and human resource development and management initiatives to sustain the supply of RNs in the subregion. © 2012 Sigma Theta Tau International.

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.

The Effect of Primary Care Provider Turnover on Patient Experience of Care and Ambulatory Quality of Care

PubMed Central

Reddy, Ashok; Pollack, Craig E.; Asch, David A.; Canamucio, Anne; Werner, Rachel M.

2017-01-01

IMPORTANCE Primary care provider (PCP) turnover is common and can disrupt patient continuity of care. Little is known about the effect of PCP turnover on patient care experience and quality of care. OBJECTIVE To measure the effect of PCP turnover on patient experiences of care and ambulatory care quality. DESIGN, SETTING, AND PARTICIPANTS Observational, retrospective cohort study of a nationwide sample of primary care patients in the Veterans Health Administration (VHA). We included all patients enrolled in primary care at the VHA between 2010 and 2012 included in 1 of 2 national data sets used to measure our outcome variables: 326 374 patients in the Survey of Healthcare Experiences of Patients (SHEP; used to measure patient experience of care) associated with 8441 PCPs and 184 501 patients in the External Peer Review Program (EPRP; used to measure ambulatory care quality) associated with 6973 PCPs. EXPOSURES Whether a patient experienced PCP turnover, defined as a patient whose provider (physician, nurse practitioner, or physician assistant) had left the VHA (ie, had no patient encounters for 12 months). MAIN OUTCOMES AND MEASURES Five patient care experience measures (from SHEP) and 11 measures of quality of ambulatory care (from EPRP). RESULTS Nine percent of patients experienced a PCP turnover in our study sample. Primary care provider turnover was associated with a worse rating in each domain of patient care experience. Turnover was associated with a reduced likelihood of having a positive rating of their personal physician of 68.2% vs 74.6% (adjusted percentage point difference, −5.3; 95% CI, −6.0 to −4.7) and a reduced likelihood of getting care quickly of 36.5% vs 38.5% (adjusted percentage point difference, −1.1; 95% CI, −2.1 to −0.1). In contrast, PCP turnover was not associated with lower quality of ambulatory care except for a lower likelihood of controlling blood pressure of 78.7% vs 80.4% (adjusted percentage point difference, −1.44; 95% CI, −2.2 to −0.7). In 9 measures of ambulatory care quality, the difference between patients who experienced no PCP turnover and those who had a PCP turnover was less than 1 percentage point. These effects were moderated by the patients’ continuity with their PCP prior to turnover, with a larger detrimental effect of PCP turnover among those with higher continuity prior to the turnover. CONCLUSIONS AND RELEVANCE Primary care provider turnover was associated with worse patient experiences of care but did not have a major effect on ambulatory care quality. PMID:25985320

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.

Measuring worker turnover in long-term care: lessons from the better jobs better care demonstration.

PubMed

Barry, Theresa Teta; Kemper, Peter; Brannon, S Diane

2008-06-01

Turnover among direct-care workers (DCWs) continues to be a challenge in long-term care. Both policy makers and provider organizations recognize this issue as a major concern and are designing efforts to reduce turnover among these workers. However, there is currently no standardized method of measuring turnover to define the scope of the problem or to assess the effectiveness of interventions. This article draws on our experience of the Better Jobs Better Care Demonstration (BJBC) to explicate some important issues in measuring and interpreting turnover related to interventions designed to improve DCW jobs. We used turnover data from a selected group of BJBC providers (N = 9) to demonstrate some of the measurement issues we uncovered in developing a turnover tracking system for BJBC. We also illustrate how the data elements collected in the tracking system make it possible to construct measures that are useful at both policy and practice levels. Differences in definitions of turnover and the data elements used to construct the measure can have large effects on turn over rates, how they are used, and what they mean. Policy makers, researchers, and managers who need comparative turnover information to address the impending demand for DCWs should be aware that turnover measures differ, and they should take steps to ensure that measures they use have common definitions and data elements.

On-call work and physicians' turnover intention: the moderating effect of job strain.

PubMed

Heponiemi, Tarja; Presseau, Justin; Elovainio, Marko

2016-01-01

Physician shortage and turnover are major problems worldwide. On-call duties may be among the risk factors of high turnover rates among physicians. We investigated whether having on-call duties is associated with physicians' turnover intention and whether job strain variables moderate this association. The present study was a cross-sectional questionnaire study among 3324 (61.6% women) Finnish physicians. The analyses were conducted using analyses of covariance adjusted for age, gender, response format, specialization status and employment sector. The results showed that job strain moderated the association between being on-call and turnover intention. The highest levels of turnover intention were among those who had on-call duties and high level of job strain characterized by high demands and low control opportunities. The lowest levels of turnover intention were among those who were not on-call and who had low strain involving low demands and high control. Also, job demands moderated the association between being on-call and turnover intention; turnover intention levels were higher among those with on-call duties and high demands than those being on-call and low demands. To conclude, working on-call was related to physicians' turnover intention particularly in those with high job strain. Health care organizations should focus more attention on working arrangements and scheduling of on-call work, provide a suitable working pace and implement means to increase physicians' participation and control over their job.

East Europe Report, Economic and Industrial Affairs.

DTIC Science & Technology

1984-05-31

printed in boldface] The ordinance of 29 July 1983 of the minister of finance has signally increased the turnover tax rates for Polonia companies...zlotys per U.S. dollar. The marked increase in the turnover tax —to several dozen from just several percent—is not imposed on the producer, because that... increase in the turnover tax and the introduction of a highly progressive income tax as well as the requirement to sell to the state one-half of the

Estrogen regulates the rate of bone turnover but bone balance in ovariectomized rats is modulated by prevailing mechanical strain

NASA Technical Reports Server (NTRS)

Westerlind, K. C.; Wronski, T. J.; Ritman, E. L.; Luo, Z. P.; An, K. N.; Bell, N. H.; Turner, R. T.

1997-01-01

Estrogen deficiency induced bone loss is associated with increased bone turnover in rats and humans. The respective roles of increased bone turnover and altered balance between bone formation and bone resorption in mediating estrogen deficiency-induced cancellous bone loss was investigated in ovariectomized rats. Ovariectomy resulted in increased bone turnover in the distal femur. However, cancellous bone was preferentially lost in the metaphysis, a site that normally experiences low strain energy. No bone loss was observed in the epiphysis, a site experiencing higher strain energy. The role of mechanical strain in maintaining bone balance was investigated by altering the strain history. Mechanical strain was increased and decreased in long bones of ovariectomized rats by treadmill exercise and functional unloading, respectively. Functional unloading was achieved during orbital spaceflight and following unilateral sciatic neurotomy. Increasing mechanical loading reduced bone loss in the metaphysis. In contrast, decreasing loading accentuated bone loss in the metaphysis and resulted in bone loss in the epiphysis. Finally, administration of estrogen to ovariectomized rats reduced bone loss in the unloaded and prevented loss in the loaded limb following unilateral sciatic neurotomy in part by reducing indices of bone turnover. These results suggest that estrogen regulates the rate of bone turnover, but the overall balance between bone formation and bone resorption is influenced by prevailing levels of mechanical strain.

In vivo quantitative analysis of Talin turnover in response to force

PubMed Central

Hákonardóttir, Guðlaug Katrín; López-Ceballos, Pablo; Herrera-Reyes, Alejandra Donají; Das, Raibatak; Coombs, Daniel; Tanentzapf, Guy

2015-01-01

Cell adhesion to the extracellular matrix (ECM) allows cells to form and maintain three-dimensional tissue architecture. Cell–ECM adhesions are stabilized upon exposure to mechanical force. In this study, we used quantitative imaging and mathematical modeling to gain mechanistic insight into how integrin-based adhesions respond to increased and decreased mechanical forces. A critical means of regulating integrin-based adhesion is provided by modulating the turnover of integrin and its adhesion complex (integrin adhesion complex [IAC]). The turnover of the IAC component Talin, a known mechanosensor, was analyzed using fluorescence recovery after photobleaching. Experiments were carried out in live, intact flies in genetic backgrounds that increased or decreased the force applied on sites of adhesion. This analysis showed that when force is elevated, the rate of assembly of new adhesions increases such that cell–ECM adhesion is stabilized. Moreover, under conditions of decreased force, the overall rate of turnover, but not the proportion of adhesion complex components undergoing turnover, increases. Using point mutations, we identify the key functional domains of Talin that mediate its response to force. Finally, by fitting a mathematical model to the data, we uncover the mechanisms that mediate the stabilization of ECM-based adhesion during development. PMID:26446844

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.

Seabirds drive plant species turnover on small Mediterranean islands at the expense of native taxa.

PubMed

Vidal, E; Médail, F; Tatoni, T; Bonnet, V

2000-02-01

The analysis of long-term floristic changes was conducted on nine west-Mediterranean limestone islands (size range: 2-95 ha) which have recently undergone a severe demographic explosion in their yellow-legged gull Larus cachinnans colonies. A comparison of past and present plant inventories was used to quantify extinction-colonization events, both from a classical biogeographical perspective (per island approach) and a metapopulational perspective (per species approach). In the first approach, floristic turnover intensity was negatively related to island area and positively to gull nesting density, but was independent of island isolation. In the second, species turnover rate was compared with a set of plant species life history traits (dispersal mode, Grime CSR strategy, growth form, biogeographical type). Plants which exhibited the highest turnover rate were primarily ruderal, annual, wind-dispersed species with a wide geographic range. The severe disturbance induced by seabird activities has tended to select and favour some adapted plant species groups at the expense of indigenous island taxa. The relationships between specific turnover intensity and plant life history traits justify using the metapopulation approach and point to the importance of interspecific variations in extinction-colonization patterns.

Does Enhancing Work-Time Control and Flexibility Reduce Turnover? A Naturally Occurring Experiment

PubMed Central

Moen, Phyllis; Kelly, Erin L.; Hill, Rachelle

2011-01-01

We investigate the turnover effects of an organizational innovation (ROWE—Results Only Work Environment) aimed at moving away from standard time practices to focus on results rather than time spent at work. To model rates of turnover, we draw on survey data from a sample of employees at a corporate headquarters (N = 775) and institutional records of turnover over eight months following the ROWE implementation. We find the odds of turnover are indeed lower for employees participating in the ROWE initiative, which offers employees greater work-time control and flexibility, and that this is the case regardless of employees’ gender, age, or family life stage. ROWE also moderates the turnover effects of organizational tenure and negative home-to-work spillover, physical symptoms, and job insecurity, with those in ROWE who report these situations generally less likely to leave the organization. Additionally, ROWE reduces turnover intentions among those remaining with the corporation. This research moves the “opting-out” argument from one of private troubles to an issue of greater employee work-time control and flexibility by showing that an organizational policy initiative can reduce turnover. PMID:21532909

Understanding the factors that determine registered nurses' turnover intentions.

PubMed

Osuji, Joseph; Uzoka, Faith-Michael; Aladi, Flora; El-Hussein, Mohammed

2014-01-01

Turnover among registered nurses (RNs) produces a negative impact on the health outcomes of any health care organization. It is also recognized universally as a problem in the nursing profession. Little is known about the turnover intentions and career orientations of RNs working in Calgary, Alberta, Canada. The aim of this study is to contribute to the knowledge of and to advance the discussion on the turnover of nursing professionals. The study population consisted of RNs employed in the five major hospitals in Calgary. There were 193 surveys returned, representing a response rate of 77.2%. The results show that age and education have a negative effect on turnover intention. Education was found to have a significant negative effect on career satisfaction but not on job satisfaction and organizational commitment. Length of service has a significant negative effect on turnover intention. Role ambiguity has significant highly negative effect on career satisfaction. Growth opportunity and supervisor support have a very significant positive effect on job satisfaction, career satisfaction, and organizational commitment. External career opportunities and organizational commitment do not seem to have a significant effect on turnover intention. Career satisfaction, on the other hand, had negative significant effects on turnover intention.

Impact of work environment and work-related stress on turnover intention in physical therapists.

PubMed

Lee, Byoung-Kwon; Seo, Dong-Kwon; Lee, Jang-Tae; Lee, A-Ram; Jeon, Ha-Neul; Han, Dong-Uk

2016-08-01

[Purpose] This study was conducted to provide basic data for solutions to reduce the turnover rate of physical therapists. It should help create efficient personnel and organization management by exploring the impact of the work environment and work-related stress on turnover intention and analyzing the correlation between them. [Subjects and Methods] A survey was conducted with 236 physical therapists working at medical institutions in the Daejeon and Chungcheong areas. For the analysis on the collected data, correlational and linear regression analyses were conducted using the SPSS 18.0 program and Cronbach's alpha coefficient. [Results] The results showed a statistically significant positive correlation between turnover intention and work-related stress but a statistically significant negative correlation respectively between turnover intention and work environment. Work-related stress (β=0.415) had a significant positive impact on turnover intention and work environment (β=-0.387) had a significant negative impact on turnover intention. [Conclusion] To increase satisfaction level with the profession as well as the workplace for physical therapists, improvement of the work environment was the most necessary primary improvement.

Impact of work environment and work-related stress on turnover intention in physical therapists

PubMed Central

Lee, Byoung-kwon; Seo, Dong-kwon; Lee, Jang-Tae; Lee, A-Ram; Jeon, Ha-Neul; Han, Dong-Uk

2016-01-01

[Purpose] This study was conducted to provide basic data for solutions to reduce the turnover rate of physical therapists. It should help create efficient personnel and organization management by exploring the impact of the work environment and work-related stress on turnover intention and analyzing the correlation between them. [Subjects and Methods] A survey was conducted with 236 physical therapists working at medical institutions in the Daejeon and Chungcheong areas. For the analysis on the collected data, correlational and linear regression analyses were conducted using the SPSS 18.0 program and Cronbach’s alpha coefficient. [Results] The results showed a statistically significant positive correlation between turnover intention and work-related stress but a statistically significant negative correlation respectively between turnover intention and work environment. Work-related stress (β=0.415) had a significant positive impact on turnover intention and work environment (β=−0.387) had a significant negative impact on turnover intention. [Conclusion] To increase satisfaction level with the profession as well as the workplace for physical therapists, improvement of the work environment was the most necessary primary improvement. PMID:27630432

Making PALS through Partnerships: A Collaboration to Promote Physically Active Lafayette Students

ERIC Educational Resources Information Center

Hemphill, Michael A.; Richards, K. Andrew; Blankenship, Bonnie T.; Beck, Stephanie; Keith, Diane

2012-01-01

In 2007, the physical education program at Sunnyside Middle School in Lafayette, Indiana, was in constant flux. Teacher turnover occurred annually, facilities were subpar, the curriculum was outdated, opportunities for professional development were rare, and most importantly, students lacked maximum movement opportunities in physical education. In…

Hibernation, stress, intestinal functions, and catecholoamine turnover rate in hamsters and gerbils

NASA Technical Reports Server (NTRS)

Musacchia, X. J.

1973-01-01

Bioenergetic studies on hamsters during depressed metabolic states are reported. External support of blood glucose extended the survival times of hibernating animals. Radioresistance increased in hibernating as well as in hypothermic hamsters. Marked changes in hamster catecholamine turnover rates were observed during acclimatization to high temperature stress. High radioresistance levels of the gerbil gastrointestinal system were attributed in part to the ability of the gut to maintain functional integrity.

Dynamics of CFCs in northern temperate lakes and adjacent groundwater

USGS Publications Warehouse

Walker, John F.; Saad, David A.; Hunt, Randall J.

2007-01-01

Three dimictic lakes and one meromictic lake in and near the Trout Lake, Wisconsin, watershed were sampled to determine the variation of chlorofluorocarbon (CFC) concentrations within the lakes. The lakes were sampled during stratified conditions, during fall turnover, and during ice cover. The results demonstrate a considerable variation in CFC concentrations and corresponding atmospheric mixing ratios in the lakes sampled, both with depth and season within a given lake, and across different lakes. CFC profiles and observed degradation were not related to the groundwater inflow rate and hence are likely the result of in‐lake processes influenced by CFC degradation in the (lake) water column, CFC degradation in the lake‐bed sediments, and gas exchange rates and the duration of turnover (turnover efficiency).

[Bone turnover in children and adolescents with diabetes mellitus type 1].

PubMed

Pater, Agnieszka; Odrowąż-Sypniewska, Grażyna

2013-01-01

Biochemical bone turnover markers are fragments of protein structural elements of the bone created during the synthesis or degradation and enzymes specific for bone cells, released into the circulation during the metabolic activity of osteoblasts and osteoclasts. Bone turnover markers are used as indicators to evaluate the activity of modeling and remodeling processes. They are the result of the activity of all remodeling processes taking place at the moment in the whole skeleton. The assay allows quick assessment of the rate of bone formation and resorption processes. Among many complications in children with type 1 diabetes increased bone turnover leading to a reduction in bone mass may increase the risk of osteopenia or osteoporosis in adulthood. The aim of this manuscript is to review recent papers about bone turnover in children and adolescents with diabetes mellitus type 1.

Local and global influences on protein turnover in neurons and glia

PubMed Central

Dörrbaum, Aline R; Kochen, Lisa

2018-01-01

Regulation of protein turnover allows cells to react to their environment and maintain homeostasis. Proteins can show different turnover rates in different tissue, but little is known about protein turnover in different brain cell types. We used dynamic SILAC to determine half-lives of over 5100 proteins in rat primary hippocampal cultures as well as in neuron-enriched and glia-enriched cultures ranging from <1 to >20 days. In contrast to synaptic proteins, membrane proteins were relatively shorter-lived and mitochondrial proteins were longer-lived compared to the population. Half-lives also correlate with protein functions and the dynamics of the complexes they are incorporated in. Proteins in glia possessed shorter half-lives than the same proteins in neurons. The presence of glia sped up or slowed down the turnover of neuronal proteins. Our results demonstrate that both the cell-type of origin as well as the nature of the extracellular environment have potent influences on protein turnover. PMID:29914620

Organizational Climate Partially Mediates the Effect of Culture on Work Attitudes and Staff Turnover in Mental Health Services

PubMed Central

Aarons, Gregory A.; Sawitzky, Angelina C.

2006-01-01

Staff turnover in mental health service organizations is an ongoing problem with implications for staff morale, productivity, organizational effectiveness, and implementation of innovation. Recent studies in public sector services have examined the impact of organizational culture and climate on work attitudes (i.e., job satisfaction and organizational commitment) and, ultimately, staff turnover. However, mediational models of the impact of culture and climate on work attitudes have not been examined. The present study examined full and partial mediation models of the effects of culture and climate on work attitudes and the subsequent impact of work attitudes on staff turnover. Multilevel structural equation models supported a partial mediation model in which organizational culture had both direct influence on work attitudes and indirect influence through organizational climate. Work attitudes significantly predicted one-year staff turnover rates. These findings support the contention that both culture and climate impact work attitudes and subsequent staff turnover. PMID:16544205

Organizational climate partially mediates the effect of culture on work attitudes and staff turnover in mental health services.

PubMed

Aarons, Gregory A; Sawitzky, Angelina C

2006-05-01

Staff turnover in mental health service organizations is an ongoing problem with implications for staff morale, productivity, organizational effectiveness, and implementation of innovation. Recent studies in public sector services have examined the impact of organizational culture and climate on work attitudes (i.e., job satisfaction and organizational commitment) and, ultimately, staff turnover. However, mediational models of the impact of culture and climate on work attitudes have not been examined. The present study examined full and partial mediation models of the effects of culture and climate on work attitudes and the subsequent impact of work attitudes on staff turnover. Multilevel structural equation models supported a partial mediation model in which organizational culture had both direct influence on work attitudes and indirect influence through organizational climate. Work attitudes significantly predicted one-year staff turnover rates. These findings support the contention that both culture and climate impact work attitudes and subsequent staff turnover.

Copper effects on bacterial activity of estuarine silty sediments

NASA Astrophysics Data System (ADS)

Almeida, Adelaide; Cunha, Ângela; Fernandes, Sandra; Sobral, Paula; Alcântara, Fernanda

2007-07-01

Bacteria of silty estuarine sediments were spiked with copper to 200 μg Cu g -1 dry weight sediment in order to assess the impact of copper on bacterial degradation of organic matter and on bacterial biomass production. Bacterial density was determined by direct counting under epifluorescence microscopy and bacterial production by the incorporation of 3H-Leucine. Leucine turnover rate was evaluated by 14C-leucine incorporation and ectoenzymatic activities were estimated as the hydrolysis rate of model substrates for β-glucosidase and leucine-aminopeptidase. The presence of added copper in the microcosms elicited, after 21 days of incubation, generalised anoxia and a decrease in organic matter content. The non-eroded surface of the copper-spiked sediment showed, when compared to the control, a decrease in bacterial abundance and significant lower levels of bacterial production and of leucine turnover rate. Bacterial production and leucine turnover rate decreased to 1.4% and 13% of the control values, respectively. Ectoenzymatic activities were also negatively affected but by smaller factors. After erosion by the water current in laboratory flume conditions, the eroded surface of the control sediment showed a generalised decline in all bacterial activities. The erosion of the copper-spiked sediment showed, however, two types of responses with respect to bacterial activities at the exposed surface: positive responses of bacterial production and leucine turnover rate contrasting with slight negative responses of ectoenzymatic activities. The effects of experimental erosion in the suspended cells were also different in the control and in the copper-spiked sediment. Bacterial cells in the control microcosm exhibited, when compared to the non-eroded sediment cells, decreases in all activities after the 6-h suspension. The response of the average suspended copper-spiked sediment cell differed from the control by a less sharp decrease in ectoenzymatic activities and, mainly, by the great intensification of bacterial biomass production and leucine turnover rate. We conclude that the bacterial community of silty estuarine sediments seems to withstand considerable concentrations of copper at the cost of reduced bacterial organic matter degradation and of the almost halting of bacterial production. The toxic effects elicited by copper on protein and carbohydrate degradation were not rapidly repaired by erosion and oxygenation of the sediment cells but, in contrast, bacterial biomass production and leucine turnover were rapidly and efficiently reactivated.

Patient-centered medical home implementation and primary care provider turnover.

PubMed

Sylling, Philip W; Wong, Edwin S; Liu, Chuan-Fen; Hernandez, Susan E; Batten, Adam J; Helfrich, Christian D; Nelson, Karin; Fihn, Stephan D; Hebert, Paul L

2014-12-01

The Veterans Health Administration (VHA) began implementing a patient-centered medical home (PCMH) model of care delivery in April 2010 through its Patient Aligned Care Team (PACT) initiative. PACT represents a substantial system reengineering of VHA primary care and its potential effect on primary care provider (PCP) turnover is an important but unexplored relationship. This study examined the association between a system-wide PCMH implementation and PCP turnover. This was a retrospective, longitudinal study of VHA-employed PCPs spanning 29 calendar quarters before PACT and eight quarters of PACT implementation. PCP employment periods were identified from administrative data and turnover was defined by an indicator on the last quarter of each uncensored period. An interrupted time series model was used to estimate the association between PACT and turnover, adjusting for secular trend and seasonality, provider and job characteristics, and local unemployment. We calculated average marginal effects (AME), which reflected the change in turnover probability associated with PACT implementation. The quarterly rate of PCP turnover was 3.06% before PACT and 3.38% after initiation of PACT. In adjusted analysis, PACT was associated with a modest increase in turnover (AME=4.0 additional PCPs per 1000 PCPs per quarter, P=0.004). Models with interaction terms suggested that the PACT-related change in turnover was increasing in provider age and experience. PACT was associated with a modest increase in PCP turnover, concentrated among older and more experienced providers, during initial implementation. Our findings suggest that policymakers should evaluate potential workforce effects when implementing PCMH.

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.

The structure and productivity of the Thalassia testudinum community in Bon Accord Lagoon, Tobago.

PubMed

Juman, Rahanna A

2005-05-01

The Thalassia testudinum dominated seagrass community in the Buccoo Reef/ Bon Accord Lagoon Marine Park, measures 0.5 km(2) and is part of a contiguous coral reef, seagrass bed and mangrove swamp system in southwest Tobago. 7 testudinum coverage, productivity and percent turnover rates were measured from February 1998 to February 1999 at four sample locations, while total T. testudinum biomass was measured at two locations in the lagoon from 1992-2002. Productivity and turnover rates varied spatially and seasonally. They were higher in the back-reef area than in the mangrove-fringed lagoon, and were lowest at locations near to a sewage outfall. 7 testudinum coverage ranged from 6.6% in the lagoon to 68.5% in the back-reef area while productivity ranged from 3.9 to 4.9 g dry wt m(-2) d(-1) . Productivity and percentage turnover rates were higher in the dry season (January-June) than in the wet season (July-December). Productivity ranged from 3.0 in the wet season to 5.0 g dry wt m2 d-' in the dry season while percentage turnover rates ranged from 4.2% to 5.6%. Total Thalassia biomass and productivity in Bon Accord Lagoon were compared to six similar sites in the Caribbean that also participate in the Caribbean Coastal Marine Productivity Program (CARICOMP). This seagrass community is being negatively impacted by nutrient-enriched conditions.

Show Me the Money: Impact of County Funding on Retention Rates for Extension Educators

ERIC Educational Resources Information Center

Feldhues, Katherine; Tanner, Timothy

2017-01-01

Extension administrators contemplating the challenge of employee turnover should consider potential motivation factors. Through the lens of Herzberg's motivation-hygiene theory, we explored the relationship between financial uncertainty and employee turnover in Ohio State University Extension. The Human Resources department and Business Office of…

Principal Turnover: Upheaval and Uncertainty in Charter Schools?

ERIC Educational Resources Information Center

Ni, Yongmei; Sun, Min; Rorrer, Andrea

2015-01-01

Purpose: Informed by literature on labor market and school choice, this study aims to examine the dynamics of principal career movements in charter schools by comparing principal turnover rates and patterns between charter schools and traditional public schools. Research Methods/Approach: This study uses longitudinal data on Utah principals and…

Using Job Embeddedness to Explain New Teacher Retention

ERIC Educational Resources Information Center

Watson, Jennifer Moradian; Olson-Buchanan, Julie

2016-01-01

The high turnover rates among teachers, particularly novice teachers, is a significant problem in the field of education. This study examines the relationship between teacher turnover and a construct found in organizational literature--job embeddedness. Job embeddedness is the extent to which an employee connects socially and emotionally to their…

Turnover of dhurrin in green sorghum seedlings. [Sorghum bicolor

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

Adewusi, S.R.A.

1990-11-01

The turnover of dhurrin in green seedlings of Sorghum bicolor (Linn) Moench var Redland x Greenleaf, Sudan 70 has been investigated using glyphosate and pulse-labeling studies with {sup 14}C-tyrosine and ({sup 14}C)shikimic acid. The rate of dhurrin breakdown was 4.8 nanomoles per hour in the shoot and 1.4 nanomoles per hour in the root. The rate of dhurrin accumulation in the shoot of 4- to 5-day-old seedlings was high but decreased with age until at the peak period of dhurrin accumulation, the rates of dhurrin synthesis and breakdown were equal. Using a first order equation (an approximation) the rate ofmore » dhurrin synthesis (which equals accumulation plus breakdown rates) was 17.4 nanomoles per hour in the shoot and 4.1 nanomoles per hour in the root. In both tissues, the breakdown rate was between 27 and 34% of their synthetic capacity within the experimental period. Dhurrin synthesis in green sorghum seedlings occurred in both the light and dark photoperiods but was faster in the dark period. The result is discussed in relation to the possible metabolic roles of the turnover.« less

The use of the exit interview to reduce turnover amongst healthcare professionals.

PubMed

Flint, Anndrea; Webster, Joan

2011-01-19

Exit interviews are widely used in healthcare organisations to identify reasons for staff attrition, yet their usefulness in limiting turnover is unclear. To determine the effectiveness of various exit interview strategies in decreasing turnover rates amongst healthcare professionals. We used a comprehensive search strategy including an electronic search of the following databases: DARE, CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO, ERIC (search date: 7 September 2010) and EPOC Specialised Register (search date: 30 September 2009). We also screened the reference lists of included studies and relevant reviews. Randomised controlled trials, controlled clinical trials, controlled before and after studies and interrupted time series studies comparing turnover rates between healthcare professionals who had undergone one form of exit interview with another form of exit interview or with no interview. Two review authors independently assessed trial quality and extracted data. The search identified 1560 citations of which we considered 19 potentially relevant. The two authors independently reviewed the abstracts of these studies and retrieved the full texts of eight studies. We excluded all eight following independent assessment. They were either interviews, commentaries on how to do an exit interview or descriptive studies about reasons for leaving. We found no trials that matched our inclusion criteria. Evidence about the effectiveness of exit interviews to reduce turnover is currently not available. However, exit interviews may provide useful information about the work environment which, in turn, may be useful in the development of interventions to reduce turnover.

Age-related accumulation of the advanced glycation endproduct pentosidine in human articular cartilage aggrecan: the use of pentosidine levels as a quantitative measure of protein turnover.

PubMed

Verzijl, N; DeGroot, J; Bank, R A; Bayliss, M T; Bijlsma, J W; Lafeber, F P; Maroudas, A; TeKoppele, J M

2001-11-01

During aging, non-enzymatic glycation results in the formation and accumulation of the advanced glycation endproduct pentosidine in long-lived proteins, such as articular cartilage collagen. In the present study, we investigated whether pentosidine accumulation also occurs in cartilage aggrecan. Furthermore, pentosidine levels in aggrecan subfractions of different residence time were used to explore pentosidine levels as a quantitative measure of aggrecan turnover. In order to compare protein turnover rates, protein residence time was measured as racemization of aspartic acid. As has previously been shown for collagen, pentosidine levels increase with age in cartilage aggrecan. Consistent with the faster turnover of aggrecan compared to collagen, the rate of pentosidine accumulation was threefold lower in aggrecan than in collagen. In the subfractions of aggrecan, pentosidine levels increased with protein residence time. These pentosidine levels were used to estimate the half-life of the globular hyaluronan-binding domain of aggrecan to be 19.5 years. This value is in good agreement with the half-life of 23.5 years that was estimated based on aspartic acid racemization. In aggrecan from osteoarthritic (OA) cartilage, decreased pentosidine levels were found compared with normal cartilage, which reflects increased aggrecan turnover during the OA disease process. In conclusion, we showed that pentosidine accumulates with age in aggrecan and that pentosidine levels can be used as a measure of turnover of long-lived proteins, both during normal aging and during disease.

The relationships between organisational citizenship behaviour, job satisfaction and turnover intention.

PubMed

Tsai, Yafang; Wu, Shih-Wang

2010-12-01

This study aims to explore the relationships between organisational citizenship behaviour, job satisfaction and turnover intention. Because of the changing health policies landscape, Taiwan's hospital administrators are facing major cost reduction challenges. Specifically, the high turnover rate of nurses represents a hindrance and a human resource cost. This study focuses on ways of reducing the employee turnover rate through enhanced organisational citizenship behaviour and job satisfaction. A cross-sectional study. This study focuses on hospital nurses in Taiwan. Our research samples were obtained from one medical centre, three regional hospitals and seven district hospitals. Out of 300 questionnaires distributed among samples, 237 were completed and returned. Pearson's correlation was used to test for relationships among the main variables. One-way analysis of variance and Scheffé's post hoc analysis were employed to test the influence of demographic data on the main variables. The results reveal that the nurses' job satisfaction has a significantly positive correlation with organisational citizenship behaviour and a negative correlation with turnover intention. This study has proven that the turnover intention of clinical nurses is related to their organisational citizenship behaviour and job satisfaction. Hospital administrators can reduce the turnover intention by meeting nurses' needs and by promoting their organisational citizenship behaviour. Organisational citizenship behaviour involves behaviour that encourages staff to endeavour to voluntarily improve organisational performance without lobbying for compensation. Employees' job satisfaction includes satisfaction with the working environment or welfare programme in the context of human resource initiatives. Similarly, human resource protocols may serve as the starting point for promoting staff organisational citizenship behaviour. Administrators in clinical healthcare are encouraged to meet their employees' working needs through human resource practices. © 2010 Blackwell Publishing Ltd.

Directions for Optimization of Photosynthetic Carbon Fixation: RuBisCO's Efficiency May Not Be So Constrained After All.

PubMed

Cummins, Peter L; Kannappan, Babu; Gready, Jill E

2018-01-01

The ubiquitous enzyme Ribulose 1,5-bisphosphate carboxylase-oxygenase (RuBisCO) fixes atmospheric carbon dioxide within the Calvin-Benson cycle that is utilized by most photosynthetic organisms. Despite this central role, RuBisCO's efficiency surprisingly struggles, with both a very slow turnover rate to products and also impaired substrate specificity, features that have long been an enigma as it would be assumed that its efficiency was under strong evolutionary pressure. RuBisCO's substrate specificity is compromised as it catalyzes a side-fixation reaction with atmospheric oxygen; empirical kinetic results show a trend to tradeoff between relative specificity and low catalytic turnover rate. Although the dominant hypothesis has been that the active-site chemistry constrains the enzyme's evolution, a more recent study on RuBisCO stability and adaptability has implicated competing selection pressures. Elucidating these constraints is crucial for directing future research on improving photosynthesis, as the current literature casts doubt on the potential effectiveness of site-directed mutagenesis to improve RuBisCO's efficiency. Here we use regression analysis to quantify the relationships between kinetic parameters obtained from empirical data sets spanning a wide evolutionary range of RuBisCOs. Most significantly we found that the rate constant for dissociation of CO 2 from the enzyme complex was much higher than previous estimates and comparable with the corresponding catalytic rate constant. Observed trends between relative specificity and turnover rate can be expressed as the product of negative and positive correlation factors. This provides an explanation in simple kinetic terms of both the natural variation of relative specificity as well as that obtained by reported site-directed mutagenesis results. We demonstrate that the kinetic behaviour shows a lesser rather than more constrained RuBisCO, consistent with growing empirical evidence of higher variability in relative specificity. In summary our analysis supports an explanation for the origin of the tradeoff between specificity and turnover as due to competition between protein stability and activity, rather than constraints between rate constants imposed by the underlying chemistry. Our analysis suggests that simultaneous improvement in both specificity and turnover rate of RuBisCO is possible.

Factors influencing the turnover and net isotopic discrimination of hydrogen isotopes in proteinaceous tissue: experimental results using Japanese quail.

PubMed

Storm-Suke, Andrea; Norris, D Ryan; Wassenaar, Leonard I; Chin, Eunice; Nol, Erica

2012-01-01

Stable hydrogen isotopes (δ(2)H) are commonly used in studies of animal movement. Tissue that is metabolically inactive after growth (e.g., feathers) provides spatial or dietary information that reflects only the period of tissue growth, whereas tissues that are metabolically active (e.g., red blood cells) provide a moving window of forensic information. However, using δ(2)H for studies of animal movement relies on the assumption that tissue δ(2)H values reflect dietary δ(2)H values, plus or minus a net diet-tissue discrimination value, and that the turnover rate is known for metabolically active tissue. The metabolic rate of an animal may influence both diet-tissue discrimination values and isotopic tissue turnover rate, but this hypothesis has not been tested experimentally. To examine the metabolic hypothesis, an experimental group of 12 male and 15 female captive Japanese quail (Coturnix japonica) was housed at 8.9°C for 90 d to elevate their metabolic rates (mL CO(2) min(-1)), and a control group of 12 male and 13 female quail was housed at room temperature during the same period. For both experimental and control birds, diet-tissue discrimination values were estimated for red blood cells and feathers. To determine turnover rate, experimental and control birds were switched from a (2)H-enriched diet to a (2)H-depleted diet, with red blood cells sampled before and after diet switch. Metabolic rate did not influence red blood cell hydrogen isotope turnover rate (η(2)(p) = 0.24)) or diet-feather isotope discrimination values (η(2)(p) = 0.86). Diet-feather hydrogen isotopic discrimination had a significant sex plus treatment interaction effect; female feathers were depleted in (2)H relative to food regardless of treatment, whereas male feathers were enriched in (2)H. The effect of sex suggested that experimental studies should examine whether coeval males and females differ in blood δ(2)H levels during certain periods of the annual cycle.

Turnover of muscle lipids and response to exercise differ between neutral and polar fractions in a model songbird, the zebra finch.

PubMed

Carter, Wales A; Cooper-Mullin, Clara; McWilliams, Scott R

2018-03-19

The turnover rates of tissues and their constituent molecules give us insights into animals' physiological demands and their functional flexibility over time. Thus far, most studies of this kind have focused on protein turnover, and few have considered lipid turnover despite an increasing appreciation of the functional diversity of this class of molecules. We measured the turnover rates of neutral and polar lipids from the pectoralis muscles of a model songbird, the zebra finch ( Taeniopygia guttata , N =65), in a 256 day C 3 /C 4 diet shift experiment, with tissue samples taken at 10 time points. We also manipulated the physiological state of a subset of these birds with a 10 week flight training regimen to test the effect of exercise on lipid turnover. We measured lipid δ 13 C values via isotope ratio mass spectrometry (IRMS) and estimated turnover in different fractions and treatment groups with non-linear mixed-effect regression. We found a significant difference between the mean retention times (τ) of neutral and polar lipids ( t 119 =-2.22, P =0.028), with polar lipids (τ=11.80±1.28 days) having shorter retention times than neutral lipids (τ=19.47±3.22 days). When all birds were considered, we also found a significant decrease in the mean retention time of polar lipids in exercised birds relative to control birds (difference=-2.2±1.83 days, t 56 =-2.37, P =0.021), but not neutral lipids (difference=4.2± 7.41 days, t 56 =0.57, P =0.57). A larger, more variable neutral lipid pool and the exposure of polar lipids in mitochondrial membranes to oxidative damage and increased turnover provide mechanisms consistent with our results. © 2018. Published by The Company of Biologists Ltd.

Effect of extradural blockage upon glucose and urea kinetics in surgical patients

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

Shaw, J.H.; Galler, L.; Holdaway, I.M.

1987-09-01

We have determined the metabolic effects induced by the use of extradural blockage with 0.5 per cent bupivacaine hydrochloride in a group of surgical patients. Turnover rates of glucose and urea were determined isotopically using radioisotopes and studies were performed both in the basal state and during total parenteral nutrition. In the basal state, extradural blockade resulted in a decrease in the turnover rates of both glucose and urea. In addition, when extradural blockade was instituted while the patients were receiving total parenteral nutrition, there was also a significant fall in glucose turnover. We conclude that the use of extraduralmore » blockade is effective as a means of conserving bodily resources in surgical patients both in the basal state and during total parenteral nutrition.« less

Contrasting above- and belowground organic matter decomposition and carbon and nitrogen dynamics in response to warming in High Arctic tundra.

PubMed

Blok, Daan; Faucherre, Samuel; Banyasz, Imre; Rinnan, Riikka; Michelsen, Anders; Elberling, Bo

2018-06-01

Tundra regions are projected to warm rapidly during the coming decades. The tundra biome holds the largest terrestrial carbon pool, largely contained in frozen permafrost soils. With warming, these permafrost soils may thaw and become available for microbial decomposition, potentially providing a positive feedback to global warming. Warming may directly stimulate microbial metabolism but may also indirectly stimulate organic matter turnover through increased plant productivity by soil priming from root exudates and accelerated litter turnover rates. Here, we assess the impacts of experimental warming on turnover rates of leaf litter, active layer soil and thawed permafrost sediment in two high-arctic tundra heath sites in NE-Greenland, either dominated by evergreen or deciduous shrubs. We incubated shrub leaf litter on the surface of control and warmed plots for 1 and 2 years. Active layer soil was collected from the plots to assess the effects of 8 years of field warming on soil carbon stocks. Finally, we incubated open cores filled with newly thawed permafrost soil for 2 years in the active layer of the same plots. After field incubation, we measured basal respiration rates of recovered thawed permafrost cores in the lab. Warming significantly reduced litter mass loss by 26% after 1 year incubation, but differences in litter mass loss among treatments disappeared after 2 years incubation. Warming also reduced litter nitrogen mineralization and decreased the litter carbon to nitrogen ratio. Active layer soil carbon stocks were reduced 15% by warming, while soil dissolved nitrogen was reduced by half in warmed plots. Warming had a positive legacy effect on carbon turnover rates in thawed permafrost cores, with 10% higher respiration rates measured in cores from warmed plots. These results demonstrate that warming may have contrasting effects on above- and belowground tundra carbon turnover, possibly governed by microbial resource availability. © 2017 John Wiley & Sons Ltd.

Glucose tracer, kinetics and turnover in monkeys and chickens infused with ethanol, 1,3-butanediol, or fructose

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

Armstrong, M.K.

1985-01-01

Mixtures of (2-/sup 3/H) and (U-/sup 14/C) glucose were injected as single doses into fasted cynomolgus monkeys to assess glucose tracer kinetics and obtain rates of turnover. Data were treated by stochastic and compartmental analyses and results from both analyses closely agreed. However, (2-/sup 3/H) data analyzed by the compartmental analysis required three pools to fit the glucose disappearance curve while (6-/sup 3/H) data fit a two or three pool model equally well. Turnover rates averaged 4.9-4.0, and 3.0 mg/min x kg/sup -1/ body weight with (2-/sup 3/H), 6-/sup 3/H) and (U-/sup 14/C) glucose tracers, respectively. The data heuristically suggestmore » that the slow turnover pool that was necessary to fit (2-/sup 3/H) glucose data is related to isotope discrimination. The effects of four treatment solutions on (6-/sup 3/H) glucose metabolism in monkeys were examined. The solutions and their rates of infusion (umoles/min x kg/sup -1/) were: (1) ethanol, 110; (2) 1,3-butanediol, 110; (3) fructose, 30; and (4) ethanol pus fructose, 110 and 30, respectively. The glucose clearance rate was lowest during the ethanol plus fructose infusions. Ethanol infusions (222 or 444 umoles/min x kg/sup -1/ body weight) in chickens (1500 g) fasted 64 hours did not cause hypoglycemia although the high dose slightly decreased the rate of glucose turnover 15% (14.0 versus 12.0 mg/min x kg/sup -1/). It was further found that neither the hepatic cytosolic nor the mitochondrial redox state significantly changed in chickens infused with the high dose of ethanol. The unchanged hepatic metabolite ratios in chickens are consistent with their unusual resistance to ethanol-induced hypoglycemia.« less

Proteomic Analysis of Altered Extracellular Matrix Turnover in Bleomycin-induced Pulmonary Fibrosis

PubMed Central

Decaris, Martin L.; Gatmaitan, Michelle; FlorCruz, Simplicia; Luo, Flora; Li, Kelvin; Holmes, William E.; Hellerstein, Marc K.; Turner, Scott M.; Emson, Claire L.

2014-01-01

Fibrotic disease is characterized by the pathological accumulation of extracellular matrix (ECM) proteins. Surprisingly, very little is known about the synthesis and degradation rates of the many proteins and proteoglycans that constitute healthy or pathological extracellular matrix. A comprehensive understanding of altered ECM protein synthesis and degradation during the onset and progression of fibrotic disease would be immensely valuable. We have developed a dynamic proteomics platform that quantifies the fractional synthesis rates of large numbers of proteins via stable isotope labeling and LC/MS-based mass isotopomer analysis. Here, we present the first broad analysis of ECM protein kinetics during the onset of experimental pulmonary fibrosis. Mice were labeled with heavy water for up to 21 days following the induction of lung fibrosis with bleomycin. Lung tissue was subjected to sequential protein extraction to fractionate cellular, guanidine-soluble ECM proteins and residual insoluble ECM proteins. Fractional synthesis rates were calculated for 34 ECM proteins or protein subunits, including collagens, proteoglycans, and microfibrillar proteins. Overall, fractional synthesis rates of guanidine-soluble ECM proteins were faster than those of insoluble ECM proteins, suggesting that the insoluble fraction reflected older, more mature matrix components. This was confirmed through the quantitation of pyridinoline cross-links in each protein fraction. In fibrotic lung tissue, there was a significant increase in the fractional synthesis of unique sets of matrix proteins during early (pre-1 week) and late (post-1 week) fibrotic response. Furthermore, we isolated fast turnover subpopulations of several ECM proteins (e.g. type I collagen) based on guanidine solubility, allowing for accelerated detection of increased synthesis of typically slow-turnover protein populations. This establishes the presence of multiple kinetic pools of pulmonary collagen in vivo with altered turnover rates during evolving fibrosis. These data demonstrate the utility of dynamic proteomics in analyzing changes in ECM protein turnover associated with the onset and progression of fibrotic disease. PMID:24741116

Norepinephrine turnover in heart and spleen of 7-, 22-, and 34 C-acclimated hamsters

NASA Technical Reports Server (NTRS)

Jones, S. B.; Musacchia, X. J.

1976-01-01

The relationship of norepinephrine (NE) concentration and endogenous turnover rates in both myocardial and spleen tissues in the golden hamster is examined as a function of chronic exposure to either high or low ambient temperatures. Changes in myocardial and spleen NE turnover values are discussed in terms of functional alterations in sympathetic nerve activity and the importance of such changes in temperature acclimation. It is found that acclimation of hamsters to 7 C for 7-10 weeks results in decreased myocardial NE concentration and an apparent increase in myocardial NE turnover. In contrast, exposure to 34 C for 6-8 weeks results in increased myocardial NE concentration and an apparent decrease in NE turnover in both myocardial and spleen tissues. The implication of altered NE synthesis is that sympathetic nerve activity is reduced with heat acclimation and is enhanced with cold acclimation.

Retaining the nursing workforce: factors contributing to the reduction of nurses' turnover intention in Japan.

PubMed

Takase, Miyuki; Teraoka, Sachiko; Yabase, Kousuke

2016-01-01

The aim of this study was to investigate the effects of psychological contract fulfilment, perceived advancement opportunities and age on reducing the turnover intention of nurses in Japan. The factors that contribute to and mitigate the intentions of nurses to leave their organisations need to be investigated to understand the determinants of nurse turnover better. However, there is a paucity of studies identifying these mitigating factors. Potential participants were 1337 registered nurses and midwives, of whom 766 participated in the study (a return rate of 57%). The data were analysed using a moderated regression analysis. Fulfilment of the psychological contract and perceived advancement opportunities independently and jointly contributed to a reduction in nurses' turnover intentions. The results also showed that nurses' ages were negatively correlated with their turnover intentions. Fulfilment of the psychological contract and advancement opportunities are important for reducing nurses' turnover intentions, especially among younger nurses. Clear guidelines/evaluations of contributions made by nurses and their organisations are needed to enhance the experience of nurses in terms of psychological contract fulfilment. Moreover, a structured advancement support system needs to be implemented to reduce nurses' turnover intentions. © 2014 John Wiley & Sons Ltd.

Therapist turnover and new program sustainability in mental health clinics as a function of organizational culture, climate, and service structure.

PubMed

Glisson, Charles; Schoenwald, Sonja K; Kelleher, Kelly; Landsverk, John; Hoagwood, Kimberly Eaton; Mayberg, Stephen; Green, Philip

2008-03-01

The present study incorporates organizational theory and organizational characteristics in examining issues related to the successful implementation of mental health services. Following the theoretical foundations of socio-technical and cultural models of organizational effectiveness, organizational climate, culture, legal and service structures, and workforce characteristics are examined as correlates of therapist turnover and new program sustainability in a nationwide sample of mental health clinics. Results of General Linear Modeling (GLM) with the organization as the unit of analysis revealed that organizations with the best climates as measured by the Organizational Social Context (OSC) profiling system, had annual turnover rates (10%) that were less than half the rates found in organizations with the worst climates (22%). In addition, organizations with the best culture profiles sustained new treatment or service programs over twice as long (50 vs. 24 months) as organizations with the worst cultures. Finally, clinics with separate children's services units had higher turnover rates than clinics that served adults and children within the same unit. The findings suggest that strategies to support the implementation of new mental health treatments and services should attend to organizational culture and climate, and to the compatibility of organizational service structures with the demand characteristics of treatments.

Nursing staff turnover at a Swedish university hospital: an exploratory study.

PubMed

Sellgren, Stina F; Kajermo, Kerstin N; Ekvall, Göran; Tomson, Göran

2009-11-01

The aim was to explore opinions on individual needs and other factors that may influence nursing staff turnover. High staff turnover is a great problem for many hospitals. It is shown to have a negative effect on the quality of nursing care and to increase hospital costs. In 2004 in a large university hospital in Sweden five focus group discussions (FGDs) including department heads (1), nursing managers (2) and members of nursing staff (2) were carried out. The questions to be addressed were 'Why do nurses leave?' and 'Why do nurses stay?' In addition, register data of staff turnover for 2002-2003 were analysed in relation to different facts about the units, such as number of employees, type of care and medical specialty. Categories of opinions identified in the FGDs were compared with results of the statistical analyses on the relationship between staff turnover and unit parameters to identify overall factors that may influence on nurse staff turnover. Four major factors were identified as having a possible influence on staff turnover: 'intrinsic values of motivation', 'work load', 'unit size 'and 'leadership'. Smaller units had lower staff turnover as well as outpatient units and day care. It was not possible to compare statements from participants from smaller units with those from participants from larger units. Two factors had diverging data, 'salary' and 'spirit of the time'. A surprising finding was the little mention of patient care in relation to staff turnover. It is important for managers to ensure that intrinsic values of nurses are met to minimise the risk for high turnover rates. Inpatient care must receive adequate staffing and nursing care could be organised into smaller units or work teams to avoid dissatisfaction and high turnover.

Large-Scale Variation in Forest Carbon Turnover Rate and its Relation to Climate - Remote Sensing vs. Global Vegetation Models

NASA Astrophysics Data System (ADS)

Carvalhais, N.; Thurner, M.; Beer, C.; Forkel, M.; Rademacher, T. T.; Santoro, M.; Tum, M.; Schmullius, C.

2015-12-01

While vegetation productivity is known to be strongly correlated to climate, there is a need for an improved understanding of the underlying processes of vegetation carbon turnover and their importance at a global scale. This shortcoming has been due to the lack of spatially extensive information on vegetation carbon stocks, which we recently have been able to overcome by a biomass dataset covering northern boreal and temperate forests originating from radar remote sensing. Based on state-of-the-art products on biomass and NPP, we are for the first time able to study the relation between carbon turnover rate and a set of climate indices in northern boreal and temperate forests. The implementation of climate-related mortality processes, for instance drought, fire, frost or insect effects, is often lacking or insufficient in current global vegetation models. In contrast to our observation-based findings, investigated models from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT, are able to reproduce spatial climate - turnover rate relationships only to a limited extent. While most of the models compare relatively well to observation-based NPP, simulated vegetation carbon stocks are severely biased compared to our biomass dataset. Current limitations lead to considerable uncertainties in the estimated vegetation carbon turnover, contributing substantially to the forest feedback to climate change. Our results are the basis for improving mortality concepts in global vegetation models and estimating their impact on the land carbon balance.

3,4-Dihydroxyphenylacetate 2,3-dioxygenase from Pseudomonas aeruginosa: An Fe(II)-containing enzyme with fast turnover

PubMed Central

Kamutira, Philaiwarong; Watthaisong, Pratchaya; Thotsaporn, Kittisak; Tongsook, Chanakan; Juttulapa, Maneerat; Nijvipakul, Sarayut; Chaiyen, Pimchai

2017-01-01

3,4-dihydroxyphenylacetate (DHPA) dioxygenase (DHPAO) from Pseudomonas aeruginosa (PaDHPAO) was overexpressed in Escherichia coli and purified to homogeneity. As the enzyme lost activity over time, a protocol to reactivate and conserve PaDHPAO activity has been developed. Addition of Fe(II), DTT and ascorbic acid or ROS scavenging enzymes (catalase or superoxide dismutase) was required to preserve enzyme stability. Metal content and activity analyses indicated that PaDHPAO uses Fe(II) as a metal cofactor. NMR analysis of the reaction product indicated that PaDHPAO catalyzes the 2,3-extradiol ring-cleavage of DHPA to form 5-carboxymethyl-2-hydroxymuconate semialdehyde (CHMS) which has a molar absorptivity of 32.23 mM-1cm-1 at 380 nm and pH 7.5. Steady-state kinetics under air-saturated conditions at 25°C and pH 7.5 showed a Km for DHPA of 58 ± 8 μM and a kcat of 64 s-1, indicating that the turnover of PaDHPAO is relatively fast compared to other DHPAOs. The pH-rate profile of the PaDHPAO reaction shows a bell-shaped plot that exhibits a maximum activity at pH 7.5 with two pKa values of 6.5 ± 0.1 and 8.9 ± 0.1. Study of the effect of temperature on PaDHPAO activity indicated that the enzyme activity increases as temperature increases up to 55°C. The Arrhenius plot of ln(k’cat) versus the reciprocal of the absolute temperature shows two correlations with a transition temperature at 35°C. Two activation energy values (Ea) above and below the transition temperature were calculated as 42 and 14 kJ/mol, respectively. The data imply that the rate determining steps of the PaDHPAO reaction at temperatures above and below 35°C may be different. Sequence similarity network analysis indicated that PaDHPAO belongs to the enzyme clusters that are largely unexplored. As PaDHPAO has a high turnover number compared to most of the enzymes previously reported, understanding its biochemical and biophysical properties should be useful for future applications in biotechnology. PMID:28158217

Work-to-family conflict as a mediator of the relationship between job satisfaction and turnover intention.

PubMed

Chen, I-Hui; Brown, Roger; Bowers, Barbara J; Chang, Wen-Yin

2015-10-01

To investigate the mediating effect of work-to-family conflict on the relationship between job satisfaction and turnover intention among licensed nurses in long-term care settings. The considerable research on turnover in long-term care has primarily focused on the impact of job satisfaction on turnover intention. Given the well-documented high turnover rate in nursing home staffing, dissatisfaction is expected to continue. Alternatives (e.g. reduction in work-to-family conflict) for reducing turnover under the circumstance of job dissatisfaction have not been investigated extensively. A cross-sectional mailed survey. A convenience sample comprising 200 nurses from 25 private nursing homes in Central Taiwan was created. Data were collected from nurses about their level of turnover intention, job satisfaction and work-to-family conflict in 2012. A composite indicator structural equation model was used to examine the mediation model of this study. Overall, 186 nurses (93%) returned the completed questionnaires. Consistent with published research from other countries, turnover intention in our study was significantly and negatively associated with job satisfaction and significantly and positively associated with work-to-family conflict. In addition, job dissatisfaction indirectly influenced turnover intention through high work-to-family conflict. Findings from this study indicate the importance of work-to-family conflict to nurse turnover. While work setting has a strong, well-documented influence on job satisfaction, limiting job satisfaction efforts to work setting improvements may not yield the hoped-for results unless work-to-family conflict is also considered and addressed. © 2015 John Wiley & Sons Ltd.

An Investigation into Factors Leading to the Longevity in Tenure of California Community College Presidents

ERIC Educational Resources Information Center

McDonald, Christopher

2012-01-01

Community colleges are experiencing many challenges that stem from political and fiscal uncertainties and these challenges are often exacerbated by high turnover in executive leadership positions (Floyd et al., 2010), which has implications for longterm strategic planning. The magnitude of the problems associated with high turnover rates for…

PATTERNS OF ROOT GROWTH, TURNOVER, AND DISTRIBUTION IN DIFFERENT AGED PONDEROSA PINE STANDS

EPA Science Inventory

The objectives of this study are to examine the spatial distribution of roots in relation to canopy size and tree distribution, and to determine if rates of fine root production and turnover are similar in the different aged stands. During the fall of 1998, 54 clear plexiglass t...

A Study of Middle School Principal Behaviors and Their Impact on Teacher Retention

ERIC Educational Resources Information Center

Martin, Todd

2011-01-01

This dissertation was designed to investigate the causes behind teacher turnover and the connection between principal behavior, teacher working conditions, and rates of teacher turnover. In particular, this study examined behaviors that teachers in three North Carolina middle schools felt their principals displayed that helped encourage them to…

Characteristics of Teacher Induction Programs and Turnover Rates of Beginning Teachers

ERIC Educational Resources Information Center

Kang, Seok; Berliner, David C.

2012-01-01

The federal School and Staffing Survey (SASS) and Teacher Follow-up Survey (TFS) were used to examine the impacts of induction activities on beginning teacher turnover. This study excluded those teachers who moved or left schools for unavoidable and involuntary reasons, a confounding factor in previous research. This analysis revealed that three…

Mucus: A new tissue fraction for rapid determination of fish diet switching using stable isotope analysis

EPA Science Inventory

Stable isotope analysis of diet switching by fishes often is hampered by slow turnover rates of the tissues analyzed (usually muscle or fins). We examined epidermal mucus as a potentially faster turnover “tissue” that might provide a more rapid assessment of diet switching. In a ...

Staff Turnover as a Function of Performance in a Public Residential Facility.

ERIC Educational Resources Information Center

Cope, John G.; And Others

1987-01-01

The relationship between employee turnover and performance was measured for 144 leavers and 144 stayers across 32 positions in a large institution for mentally retarded people. Performance ratings for leavers were significantly lower than for stayers suggesting that the organization is not ejecting its best workers. (Author/DB)

Director Turnover: An Australian Academic Development Study

ERIC Educational Resources Information Center

Fraser, Kym; Ryan, Yoni

2012-01-01

Although it can be argued that directors of central academic development units (ADUs) are critical to the implementation of university teaching and learning strategies, it would appear there is a high director turnover rate. While research in the USA, the UK, and Australia illustrates that ADUs are frequently closed or restructured, that research…

The Causes and Effects of English Teachers' Turnover: A Case from Afghanistan

ERIC Educational Resources Information Center

Khawary, Omidullah; Ali, Sajid

2015-01-01

One of the challenging issues that educational organizations in developing countries face in staffing classrooms with qualified teachers is the high rate of teachers' turnover. It creates problems for schools, which eventually leads to substandard instruction and low student achievement. This research explores the causes of English teachers'…

[Clinical usefulness of bone turnover markers in the management of osteoporosis].

PubMed

Yano, Shozo

2013-09-01

Osteoporosis is a state of elevated risk for bone fracture due to depressed bone strength, which is considered to be the sum of bone mineral density and bone quality. Since a measure of bone quality has not been established, bone mineral density and bone turnover markers are the only way to evaluate bone strength. Bone turnover markers are classified into bone formation marker and resorption marker, which are correlated with the bone formation rate and resorption rate, respectively, and bone matrix-related marker. Bone is always metabolized; old tissue is resorbed by acids and proteases derived from osteoclasts, whereas new bone is produced by osteoblasts. Bone formation and resorption rates should be balanced (also called coupled). When the bone resorption rate exceeds the formation rate(uncoupled state), bone volume will be reduced. Thus, we can comprehend bone metabolism by measuring both formation and resorption markers at the same time. Increased fracture risk is recognized by elevated bone resorption markers and undercarboxylated osteocalcin, which reflects vitamin K insufficiency and bone turnover. These values and the time course give us helpful information to choose medicine suitable for the patients and to judge the responsiveness. If the value is extraordinarily high without renal failure, metabolic bone disorder or bone metastatic tumor should be considered. Bone quality may be assessed by measuring bone matrix-related markers such as homocystein and pentosidine. Since recent studies indicate that the bone is a hormone-producing organ, it is possible that glucose metabolism or an unknown mechanism could be assessed in the future.

Estimating tissue-specific discrimination factors and turnover rates of stable isotopes of nitrogen and carbon in the smallnose fanskate Sympterygia bonapartii (Rajidae).

PubMed

Galván, D E; Jañez, J; Irigoyen, A J

2016-08-01

This study aimed to estimate trophic discrimination factors (TDFs) and metabolic turnover rates of nitrogen and carbon stable isotopes in blood and muscle of the smallnose fanskate Sympterygia bonapartii by feeding six adult individuals, maintained in captivity, with a constant diet for 365 days. TDFs were estimated as the difference between δ(13) C or δ(15) N values of the food and the tissues of S. bonapartii after they had reached equilibrium with their diet. The duration of the experiment was enough to reach the equilibrium condition in blood for both elements (estimated time to reach 95% of turnover: C t95%blood  = 150 days, N t95%blood  = 290 days), whilst turnover rates could not be estimated for muscle because of variation among samples. Estimates of Δ(13) C and Δ(15) N values in blood and muscle using all individuals were Δ(13) Cblood = 1·7‰, Δ(13) Cmuscle = 1·3‰, Δ(15) Nblood = 2·5‰ and Δ(15) Nmuscle = 1·5‰, but there was evidence of differences of c.0·4‰ in the Δ(13) C values between sexes. The present values for TDFs and turnover rates constitute the first evidence for dietary switching in batoids based on long-term controlled feeding experiments. Overall, the results showed that S. bonapartii has relatively low turnover rates and isotopic measurements would not track seasonal movements adequately. The estimated Δ(13) C values in S. bonapartii blood and muscle were similar to previous estimations for elasmobranchs and to generally accepted values in bony fishes (Δ(13) C = 1·5‰). For Δ(15) N, the results were similar to published reports for blood but smaller than reports for muscle and notably smaller than the typical values used to estimate trophic position (Δ(15) N c. 3·4‰). Thus, trophic position estimations for elasmobranchs based on typical Δ(15) N values could lead to underestimates of actual trophic positions. Finally, the evidence of differences in TDFs between sexes reveals a need for more targeted research. © 2016 The Fisheries Society of the British Isles.

[Coping strategies: bullying in the nursing workplace].

PubMed

Tsai, Shian-Ting; Sung, Ya-Wen; Tzou, Li-Ping; Huang, Meng-Ting; Hwang, Miin-Rong; Chiou, Chii-Jun

2011-08-01

High nurse turnover rates and the related rise in patient-to-nurse ratios correlate with the integrity and maturity of nursing organizations and patient safety issues. Previous studies indicate bullying among nurses to be significantly related to high turnover rates and to impact negatively on the physical and mental health of nurses. The situation has been severe enough to lead to nurse suicides (Yildirim & Yildirim, 2007). In light of such, the International Council of Nurses (ICN) reviewed the literature about nursing workplace bullying and proclaimed the importance of fostering a positive work environment in 2007. Most studies on nursing workplace bullying have focused on western societies. In order to clarify the state of nursing bullying in Taiwan, this paper worked to summarize observations in the literature regarding the causes of and management strategies for nursing workplace bullying in order to increase the attention of nursing managers and staff toward this issue. The authors hope that this article may help raise awareness and both prevent nursing workplace bullying and reduce currently high turnover rates.

Proteins with High Turnover Rate in Barley Leaves Estimated by Proteome Analysis Combined with in Planta Isotope Labeling1[W][OPEN

PubMed Central

Nelson, Clark J.; Alexova, Ralitza; Jacoby, Richard P.; Millar, A. Harvey

2014-01-01

Protein turnover is a key component in cellular homeostasis; however, there is little quantitative information on degradation kinetics for individual plant proteins. We have used 15N labeling of barley (Hordeum vulgare) plants and gas chromatography-mass spectrometry analysis of free amino acids and liquid chromatography-mass spectrometry analysis of proteins to track the enrichment of 15N into the amino acid pools in barley leaves and then into tryptic peptides derived from newly synthesized proteins. Using information on the rate of growth of barley leaves combined with the rate of degradation of 14N-labeled proteins, we calculate the turnover rates of 508 different proteins in barley and show that they vary by more than 100-fold. There was approximately a 9-h lag from label application until 15N incorporation could be reliably quantified in extracted peptides. Using this information and assuming constant translation rates for proteins during the time course, we were able to quantify degradation rates for several proteins that exhibit half-lives on the order of hours. Our workflow, involving a stringent series of mass spectrometry filtering steps, demonstrates that 15N labeling can be used for large-scale liquid chromatography-mass spectrometry studies of protein turnover in plants. We identify a series of abundant proteins in photosynthesis, photorespiration, and specific subunits of chlorophyll biosynthesis that turn over significantly more rapidly than the average protein involved in these processes. We also highlight a series of proteins that turn over as rapidly as the well-known D1 subunit of photosystem II. While these proteins need further verification for rapid degradation in vivo, they cluster in chlorophyll and thiamine biosynthesis. PMID:25082890

Best practices to promote occupational safety and satisfaction: a comparison of three North American hospitals.

PubMed

McCaughey, Deirdre; DelliFraine, Jami; Erwin, Cathleen O

2015-01-01

Hospitals in North America consistently have employee injury rates ranking among the highest of all industries. Organizations that mandate workplace safety training and emphasize safety compliance tend to have lower injury rates and better employee safety perceptions. However, it is unclear if the work environment in different national health care systems (United States vs. Canada) is associated with different employee safety perceptions or injury rates. This study examines occupational safety and workplace satisfaction in two different countries with employees working for the same organization. Survey data were collected from environmental services employees (n = 148) at three matched hospitals (two in Canada and one in the United States). The relationships that were examined included: (1) safety leadership and safety training with individual/unit safety perceptions; (2) supervisor and coworker support with individual job satisfaction and turnover intention; and (3) unit turnover, labor usage, and injury rates. Hierarchical regression analysis and ANO VA found safety leadership and safety training to be positively related to individual safety perceptions, and unit safety grade and effects were similar across all hospitals. Supervisor and coworker support were found to be related to individual and organizational outcomes and significant differences were found across the hospitals. Significant differences were found in injury rates, days missed, and turnover across the hospitals. This study offers support for occupational safety training as a viable mechanism to reduce employee injury rates and that a codified training program translates across national borders. Significant differences were found.between the hospitals with respect to employee and organizational outcomes (e.g., turnover). These findings suggest that work environment differences are reflective of the immediate work group and environment, and may reflect national health care system differences.

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.

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.

Thermomyces lanuginosus lipase-catalyzed synthesis of natural flavor esters in a continuous flow microreactor.

PubMed

Gumel, Ahmad Mohammed; Annuar, M S M

2016-06-01

Enzymatic catalysis is considered to be among the most environmental friendly processes for the synthesis of fine chemicals. In this study, lipase from Thermomyces lanuginosus (Lecitase Ultra™) was used to catalyze the synthesis of flavor esters, i.e., methyl butanoate and methyl benzoate by esterification of the acids with methanol in a microfluidic system. Maximum reaction rates of 195 and 115 mM min -1 corresponding to catalytic efficiencies (k cat /K M ) of 0.30 and 0.24 min -1  mM -1 as well as yield conversion of 54 and 41 % were observed in methyl butanoate and methyl benzoate synthesis, respectively. Catalytic turnover (k cat ) was higher for methyl butanoate synthesis. Rate of synthesis and yield decreased with increasing flow rates. For both esters, increase in microfluidic flow rate resulted in increased advective transport over molecular diffusion and reaction rate, thus lower conversion. In microfluidic synthesis using T. lanuginosus lipase, the following reaction conditions were 40 °C, flow rate 0.1 mL min -1 , and 123 U g -1 enzyme loading found to be the optimum operating limits. The work demonstrated the application of enzyme(s) in a microreactor system for the synthesis of industrially important esters.

The relationship between occupational stress, burnout, and turnover intention among managerial staff from a Sino-Japanese joint venture in Guangzhou, China.

PubMed

Lin, Qiu-Hong; Jiang, Chao-Qiang; Lam, Tai Hing

2013-01-01

The aim of this study was to analyze the associations between occupational stress, burnout and turnover intention and explore their associated factors among managerial staff in Guangzhou, China. This cross-sectional study recruited 288 managerial employees from a Sino-Japanese joint venture automobile manufacturing enterprise in Guangzhou. The questionnaire included questions about sociodemographic characteristics, smoking, drinking and physical activity and the Chinese versio ns of the Occupational Stress Indicator (OSI), Maslach Burnout Inventory (MBI), Eysenck Personality Questionnaire (EPQ), Simplified Coping Style Questionnaire (SCSQ) and Social Support Rating Scale (SSRS). The response rate was 57.6%. Stepwise regression analysis was performed to examine the associations between burnout and occupational stress and turnover intention and related factors. The respondents had a high level burnout on the personal accomplishment subscale and had a high prevalence of turnover intention. Neuroticism, psychoticism, job satisfaction, occupational stress and social support were strong predictors of emotional exhaustion. Psychoticism, passive coping, occupational stress, objective support, utilization of support, male gender and job satisfaction were strong predictors of depersonalization. Active and passive coping and job satisfaction were strong predictors of personal accomplishment. Job dissatisfaction and emotional exhaustion were strong predictors of turnover intention. High occupational stress and low job satisfaction were associated with high burnout, particularly in the emotional exhaustion and depersonalization dimensions. Low job satisfaction and high emotional exhaustion were associated with high turnover intention among employees. Personality traits, social support and coping style were also found to be associated with burnout.

Workplace violence, job satisfaction, burnout, perceived organisational support and their effects on turnover intention among Chinese nurses in tertiary hospitals: a cross-sectional study.

PubMed

Liu, Wenhui; Zhao, Shihong; Shi, Lei; Zhang, Zhong; Liu, Xinyan; Li, Li; Duan, Xiaojian; Li, Guoqiang; Lou, Fengge; Jia, Xiaoli; Fan, Lihua; Sun, Tao; Ni, Xin

2018-06-09

Our aims were to assess the relationship between workplace violence, job satisfaction, burnout, organisational support and turnover intention, and to explore factors associated with turnover intention among nurses in Chinese tertiary hospitals. The purposive sampling method was used to collect data from August 2016 through January 2017. A total of 1761 nurses from 9 public tertiary hospitals in 4 provinces (municipalities) located in eastern (Beijing), central (Heilongjiang, Anhui) and western (Shaanxi) regions of China completed the questionnaires (effective response rate=85.20%). A cross-sectional study was conducted using the Workplace Violence Scale, Chinese Maslach Burnout Inventory General Survey, Minnesota Job Satisfaction Questionnaire Revised Short Version, Perceived Organizational Support-Simplified Version Scale and Turnover Intention Scale. A total of 1216 of 1706 (69.1%) participants had high turnover intention. During the previous 12 months, the prevalence of physical violence and psychological violence towards nurses was 9.60% and 59.64%, respectively. As expected, the level of turnover intention was negatively correlated with participants' scores on job satisfaction (r=-0.367, p<0.001) and perceived organisational support (r=-0.379, p<0.001), respectively. Burnout was positively associated with turnover intention (r=0.444, p<0.001). Workplace violence was positively associated with turnover intention (β=0.035, p<0.001) in linear regression analysis. The total effect (β=0.53) of workplace violence on turnover intention comprised its direct effect (β=0.36) and its indirect effect (β=0.17). Perceived organisational support served as a mediator between workplace violence, job satisfaction, burnout and turnover intention, and it had a significantly negative impact on turnover intention. Therefore, nursing managers should understand the importance of the organisation's support and establish a reasonable incentive system to decrease turnover intention. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Workplace violence, job satisfaction, burnout, perceived organisational support and their effects on turnover intention among Chinese nurses in tertiary hospitals: a cross-sectional study

PubMed Central

Zhang, Zhong; Liu, Xinyan; Li, Li; Duan, Xiaojian; Li, Guoqiang; Lou, Fengge; Jia, Xiaoli; Fan, Lihua; Sun, Tao; Ni, Xin

2018-01-01

Objectives Our aims were to assess the relationship between workplace violence, job satisfaction, burnout, organisational support and turnover intention, and to explore factors associated with turnover intention among nurses in Chinese tertiary hospitals. Methods The purposive sampling method was used to collect data from August 2016 through January 2017. A total of 1761 nurses from 9 public tertiary hospitals in 4 provinces (municipalities) located in eastern (Beijing), central (Heilongjiang, Anhui) and western (Shaanxi) regions of China completed the questionnaires (effective response rate=85.20%). A cross-sectional study was conducted using the Workplace Violence Scale, Chinese Maslach Burnout Inventory General Survey, Minnesota Job Satisfaction Questionnaire Revised Short Version, Perceived Organizational Support-Simplified Version Scale and Turnover Intention Scale. Results A total of 1216 of 1706 (69.1%) participants had high turnover intention. During the previous 12 months, the prevalence of physical violence and psychological violence towards nurses was 9.60% and 59.64%, respectively. As expected, the level of turnover intention was negatively correlated with participants’ scores on job satisfaction (r=−0.367, p<0.001) and perceived organisational support (r=−0.379, p<0.001), respectively. Burnout was positively associated with turnover intention (r=0.444, p<0.001). Workplace violence was positively associated with turnover intention (β=0.035, p<0.001) in linear regression analysis. The total effect (β=0.53) of workplace violence on turnover intention comprised its direct effect (β=0.36) and its indirect effect (β=0.17). Conclusions Perceived organisational support served as a mediator between workplace violence, job satisfaction, burnout and turnover intention, and it had a significantly negative impact on turnover intention. Therefore, nursing managers should understand the importance of the organisation’s support and establish a reasonable incentive system to decrease turnover intention. PMID:29886440

Substrate-induced respiration in Puerto Rican soils: minimum glucose amendment

Treesearch

Marcela Zalamea; Grizelle Gonzalez

2007-01-01

Soil microbiota –usually quantified as microbial biomass –is a key component of terrestrial ecosystems, regulating nutrient cycling and organic matter turnover. Among the several methods developed for estimating soil microbial biomass, Substrate-Induced Respiration (SIR) is considered reliable and easy to implement; once the maximum respiratory response is determined...

Large deviation theory for the kinetics and energetics of turnover of enzyme catalysis in a chemiostatic flow.

PubMed

Das, Biswajit; Gangopadhyay, Gautam

2018-05-07

In the framework of large deviation theory, we have characterized nonequilibrium turnover statistics of enzyme catalysis in a chemiostatic flow with externally controllable parameters, like substrate injection rate and mechanical force. In the kinetics of the process, we have shown the fluctuation theorems in terms of the symmetry of the scaled cumulant generating function (SCGF) in the transient and steady state regime and a similar symmetry rule is reflected in a large deviation rate function (LDRF) as a property of the dissipation rate through boundaries. Large deviation theory also gives the thermodynamic force of a nonequilibrium steady state, as is usually recorded experimentally by a single molecule technique, which plays a key role responsible for the dynamical symmetry of the SCGF and LDRF. Using some special properties of the Legendre transformation, here, we have provided a relation between the fluctuations of fluxes and dissipation rates, and among them, the fluctuation of the turnover rate is routinely estimated but the fluctuation in the dissipation rate is yet to be characterized for small systems. Such an enzymatic reaction flow system can be a very good testing ground to systematically understand the rare events from the large deviation theory which is beyond fluctuation theorem and central limit theorem.

Large deviation theory for the kinetics and energetics of turnover of enzyme catalysis in a chemiostatic flow

NASA Astrophysics Data System (ADS)

Das, Biswajit; Gangopadhyay, Gautam

2018-05-01

In the framework of large deviation theory, we have characterized nonequilibrium turnover statistics of enzyme catalysis in a chemiostatic flow with externally controllable parameters, like substrate injection rate and mechanical force. In the kinetics of the process, we have shown the fluctuation theorems in terms of the symmetry of the scaled cumulant generating function (SCGF) in the transient and steady state regime and a similar symmetry rule is reflected in a large deviation rate function (LDRF) as a property of the dissipation rate through boundaries. Large deviation theory also gives the thermodynamic force of a nonequilibrium steady state, as is usually recorded experimentally by a single molecule technique, which plays a key role responsible for the dynamical symmetry of the SCGF and LDRF. Using some special properties of the Legendre transformation, here, we have provided a relation between the fluctuations of fluxes and dissipation rates, and among them, the fluctuation of the turnover rate is routinely estimated but the fluctuation in the dissipation rate is yet to be characterized for small systems. Such an enzymatic reaction flow system can be a very good testing ground to systematically understand the rare events from the large deviation theory which is beyond fluctuation theorem and central limit theorem.

Origin of the Eumetazoa: testing ecological predictions of molecular clocks against the Proterozoic fossil record

NASA Technical Reports Server (NTRS)

Peterson, Kevin J.; Butterfield, Nicholas J.

2005-01-01

Molecular clocks have the potential to shed light on the timing of early metazoan divergences, but differing algorithms and calibration points yield conspicuously discordant results. We argue here that competing molecular clock hypotheses should be testable in the fossil record, on the principle that fundamentally new grades of animal organization will have ecosystem-wide impacts. Using a set of seven nuclear-encoded protein sequences, we demonstrate the paraphyly of Porifera and calculate sponge/eumetazoan and cnidarian/bilaterian divergence times by using both distance [minimum evolution (ME)] and maximum likelihood (ML) molecular clocks; ME brackets the appearance of Eumetazoa between 634 and 604 Ma, whereas ML suggests it was between 867 and 748 Ma. Significantly, the ME, but not the ML, estimate is coincident with a major regime change in the Proterozoic acritarch record, including: (i) disappearance of low-diversity, evolutionarily static, pre-Ediacaran acanthomorphs; (ii) radiation of the high-diversity, short-lived Doushantuo-Pertatataka microbiota; and (iii) an order-of-magnitude increase in evolutionary turnover rate. We interpret this turnover as a consequence of the novel ecological challenges accompanying the evolution of the eumetazoan nervous system and gut. Thus, the more readily preserved microfossil record provides positive evidence for the absence of pre-Ediacaran eumetazoans and strongly supports the veracity, and therefore more general application, of the ME molecular clock.

Relationships between Federal Accountability Mandates and Principal Turnover within Georgia Public Elementary Schools

ERIC Educational Resources Information Center

Garbade, Amy Leigh

2013-01-01

This study examines principal turnover in Georgia public elementary schools during a time period prior to the existence of the No Child Left Behind Act of 2001, through the law's full implementation. Data was compiled for the fourteen-year period and examined to determine if a relationship existed between principal attrition rates and the…

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…

A National Issue: Whether the Teacher Turnover Effects Students' Academic Performance?

ERIC Educational Resources Information Center

Terry, Loretta A.; Kritsonis, William Allan

2008-01-01

The high teacher turnover rate and low student academic performance are two urgent issues that threaten the education of America's children--our greatest resource. The technical core of schools nationally is to provide a quality education to produce literate generations to function in our global society. If the United States is to equip its young…

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.

Administrator turnover and quality of care in nursing homes.

PubMed

Castle, N G

2001-12-01

In this article, I examine the association between turnover of nursing home administrators and five important quality of care outcomes. The data came from a survey of 420 nursing facilities and the 1999 On-line Survey, Certification, and Reporting System. Using multivariate logistic regression analyses, I looked at the effects of turnover of administrators in nursing homes belonging to chain organizations and in nursing homes not belonging to chain organizations. I found the average annual turnover rate of administrators to be 43%. The multivariate logistic regression analyses show that in nursing homes belonging to chains, administrator turnover is associated with a higher than average proportion of residents who were catheterized, had pressure ulcers, and were given psychoactive drugs and with a higher than average number of quality-of-care deficiencies. In nursing homes not belonging to chains I found that turnover of administrators is associated with a higher than average proportion of residents who were restrained, were catheterized, had pressure ulcers, and were given psychoactive drugs. There is a need to improve understanding of how and why better outcomes are achieved in some nursing homes. This investigation serves to focus attention on nursing home administrators. I believe this study provides preliminary evidence that the turnover of administrators may have an important association with quality of care in nursing homes.

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

PubMed

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

2018-01-01

The difficulty involved in quantifying biogeochemically significant microbes in marine sediments limits our ability to assess interspecific interactions, population turnover times, and niches of uncultured taxa. We incubated surface sediments from Cape Lookout Bight, North Carolina, USA, anoxically at 21°C for 122 days. Sulfate decreased until day 68, after which methane increased, with hydrogen concentrations consistent with the predicted values of an electron donor exerting thermodynamic control. We measured turnover times using two relative quantification methods, quantitative PCR (qPCR) and the product of 16S gene read abundance and total cell abundance (FRAxC, which stands for "fraction of read abundance times cells"), to estimate the population turnover rates of uncultured clades. Most 16S rRNA reads were from deeply branching uncultured groups, and ∼98% of 16S rRNA genes did not abruptly shift in relative abundance when sulfate reduction gave way to methanogenesis. Uncultured Methanomicrobiales and Methanosarcinales increased at the onset of methanogenesis with population turnover times estimated from qPCR at 9.7 ± 3.9 and 12.6 ± 4.1 days, respectively. These were consistent with FRAxC turnover times of 9.4 ± 5.8 and 9.2 ± 3.5 days, respectively. Uncultured Syntrophaceae , which are possibly fermentative syntrophs of methanogens, and uncultured Kazan-3A-21 archaea also increased at the onset of methanogenesis, with FRAxC turnover times of 14.7 ± 6.9 and 10.6 ± 3.6 days. Kazan-3A-21 may therefore either perform methanogenesis or form a fermentative syntrophy with methanogens. Three genera of sulfate-reducing bacteria, Desulfovibrio , Desulfobacter , and Desulfobacterium , increased in the first 19 days before declining rapidly during sulfate reduction. We conclude that population turnover times on the order of days can be measured robustly in organic-rich marine sediment, and the transition from sulfate-reducing to methanogenic conditions stimulates growth only in a few clades directly involved in methanogenesis, rather than in the whole microbial community. IMPORTANCE Many microbes cannot be isolated in pure culture to determine their preferential growth conditions and predict their response to changing environmental conditions. We created a microcosm of marine sediments that allowed us to simulate a diagenetic profile using a temporal analog for depth. This allowed for the observation of the microbial community population dynamics caused by the natural shift from sulfate reduction to methanogenesis. Our research provides evidence for the population dynamics of uncultured microbes as well as the application of a novel method of turnover rate analysis for individual taxa within a mixed incubation, FRAxC, which stands for "fraction of read abundance times cells," which was verified by quantitative PCR. This allows for the calculation of population turnover times for microbes in a natural setting and the identification of uncultured clades involved in geochemical processes. Copyright © 2017 American Society for Microbiology.

Evaluation of local bone turnover in painful hip by 18F-fluoride positron emission tomography.

PubMed

Kobayashi, Naomi; Inaba, Yutaka; Tezuka, Taro; Ike, Hiroyuki; Kubota, So; Kawamura, Masaki; Saito, Tomoyuki

2016-04-01

The diagnosis of painful hip without remarkable radiographic findings is still challenging. In recent years, femoroacetabular impingement (FAI) has been recognized as an important cause of painful hip. The hypothesis of this study was that local bone turnover may be accelerated in painful hip, especially in FAI lesions. To test this, patients with unilateral symptomatic hip underwent F-fluoride PET, which directly correlates with osteoblast activity and therefore bone turnover. In total, 27 patients with unilateral symptomatic painful hip were enrolled. The diagnosis included 15 cam-type FAI cases, six labral tear cases, and six early-stage osteoarthritis cases. The region of interest for cam and pincer lesions was identified and the maximum standardized uptake value (SUVmax) in these regions and the contralateral asymptomatic regions were measured by F-fluoride PET. The SUVmax ratio was defined as symptomatic side SUVmax/asymptomatic side SUVmax. The α angle and center-edge angle were measured by plain radiograph. The SUVmax of both cam and pincer lesions were significantly higher than the SUVmax of the contralateral regions (P<0.0001). The cam SUVmax ratio correlated positively with the α angle (r=0.5, P=0.007). Patients with an α angle of more than or equal to 60° had a significantly higher cam SUVmax ratio than the less than 60° group (P=0.017). This study showed the accelerated local bone turnover in painful hip, partly in FAI cases. Accelerated bone turnover may play a significant role in FAI pathophysiology; therefore, its recognition by imaging modality may contribute toward a more sensitive diagnosis in painful hip.

Regulation of adult cardiocyte growth: effects of active and passive mechanical loading

NASA Technical Reports Server (NTRS)

Decker, M. L.; Janes, D. M.; Barclay, M. M.; Harger, L.; Decker, R. S.

1997-01-01

Fluctuations in hemodynamic load have been documented to modulate contractile protein turnover and myofibrillar structure in the heart; however, the relative importance of active and passive loading in regulating adult cardiocyte growth remains unresolved. To address this issue at the cellular level, adult feline cardiocytes were cultured either on Silastic membranes or plastic surfaces. Cardiocyte-laden membranes were stretched 10% of their rest length to enhance passive loading, whereas heart cells cultured on plastic or Silastic were field stimulated at 1 Hz to mimic active loading. Turnover of contractile proteins and structural integrity of the contractile-cytoskeletal apparatus were monitored for periods ranging from 4 to 72 h. Active and passive loading elevated contractile protein synthesis nearly equally (approximately 50%) and promoted the attachment of remodeled myofibrils to vinculin-positive focal contacts and/or costameres during the first 24 h of loading. Thereafter, rates of contractile protein synthesis returned to control values in passively stretched heart cells but remained elevated in field-stimulated cultures. The fractional rate of growth was increased significantly (approximately 8%/day) in electrically paced cells, whereas in passively stretched cardiocytes the growth rate rose only modestly (approximately 2%/day). Changes in the rate of myocyte growth appeared more closely correlated with the development of focal contacts and myofibril remodeling than with changes in myofibrillar protein turnover per se. 2,3-Butanedione monoxime, nifedipine, and, to a lesser extent, ryanodine blocked field-stimulated contractile protein synthesis and myofibrillar remodeling but had no impact on protein turnover or myofibril reassembly in passively loaded cardiocytes. The results of these experiments imply that both active and passive loading stimulate contractile protein turnover and myofibril remodeling, but the generation of active tension accelerates cardiocyte growth to a greater extent than passive loading. Furthermore, pharmacological interventions suggest that unique pathways may mediate these cellular events in actively and passively loaded adult cardiocytes.

Regulation of adult cardiocyte growth: effects of active and passive mechanical loading.

PubMed

Decker, M L; Janes, D M; Barclay, M M; Harger, L; Decker, R S

1997-06-01

Fluctuations in hemodynamic load have been documented to modulate contractile protein turnover and myofibrillar structure in the heart; however, the relative importance of active and passive loading in regulating adult cardiocyte growth remains unresolved. To address this issue at the cellular level, adult feline cardiocytes were cultured either on Silastic membranes or plastic surfaces. Cardiocyte-laden membranes were stretched 10% of their rest length to enhance passive loading, whereas heart cells cultured on plastic or Silastic were field stimulated at 1 Hz to mimic active loading. Turnover of contractile proteins and structural integrity of the contractile-cytoskeletal apparatus were monitored for periods ranging from 4 to 72 h. Active and passive loading elevated contractile protein synthesis nearly equally (approximately 50%) and promoted the attachment of remodeled myofibrils to vinculin-positive focal contacts and/or costameres during the first 24 h of loading. Thereafter, rates of contractile protein synthesis returned to control values in passively stretched heart cells but remained elevated in field-stimulated cultures. The fractional rate of growth was increased significantly (approximately 8%/day) in electrically paced cells, whereas in passively stretched cardiocytes the growth rate rose only modestly (approximately 2%/day). Changes in the rate of myocyte growth appeared more closely correlated with the development of focal contacts and myofibril remodeling than with changes in myofibrillar protein turnover per se. 2,3-Butanedione monoxime, nifedipine, and, to a lesser extent, ryanodine blocked field-stimulated contractile protein synthesis and myofibrillar remodeling but had no impact on protein turnover or myofibril reassembly in passively loaded cardiocytes. The results of these experiments imply that both active and passive loading stimulate contractile protein turnover and myofibril remodeling, but the generation of active tension accelerates cardiocyte growth to a greater extent than passive loading. Furthermore, pharmacological interventions suggest that unique pathways may mediate these cellular events in actively and passively loaded adult cardiocytes.

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.

Year-long changes in protein metabolism in elderly men and women supplemented with a nutrition cocktail of beta-hydroxy-beta-methylbutyrate (HMB), L-arginine, and L-lysine.

PubMed

Baier, Shawn; Johannsen, Darcy; Abumrad, Naji; Rathmacher, John A; Nissen, Steven; Flakoll, Paul

2009-01-01

A major contributing factor to the loss of mobility in elderly people is the gradual and continuous loss of lean body mass. To determine whether supplementation of an amino acid cocktail daily for 1 year could improve the age-associated changes in protein turnover and lean body mass in elderly people. Elderly (76+/-1.6 years) women (n=39) and men (n=38) were recruited for a double-blinded controlled study. Study participants were randomly assigned to either an isonitrogenous control-supplement (n=37) or a treatment-supplement (HMB/Arg/Lys) consisting of beta-hydroxy-beta-methylbutyrate, L-arginine, and L-lysine (n=40) for the 1-year study. Lean tissue mass was measured using both bioelectrical-impedance analysis (BIA) and dual energy x-ray absorptiometry (DXA). Rates of whole-body protein turnover were estimated using primed/intermittent oral doses of 15N-glycine. In subjects taking the HMB/Arg/Lys supplement, lean tissue increased over the year of study while in the control group, lean tissue did not change. Compared with control, HMB/Arg/Lys increased body cell mass (BIA) by 1.6% (P=.002) and lean mass (DXA) by 1.2% (P=.05). The rates of protein turnover were significantly increased 8% and 12% in the HMB/Arg/Lys-supplemented group while rates of protein turnover decreased 11% and 9% in the control-supplemented subjects (P<.01), at 3 and 12 months, respectively. Consumption of a simple amino acid-related cocktail increased protein turnover and lean tissue in elderly individuals in a year-long study.

Effects of triiodothyronine on turnover rate and metabolizing enzymes for thyroxine in thyroidectomized rats.

PubMed

Nagao, Hidenori; Sasaki, Makoto; Imazu, Tetsuya; Takahashi, Kenjo; Aoki, Hironori; Minato, Kouichi

2014-10-29

Previous studies in rats have indicated that surgical thyroidectomy represses turnover of serum thyroxine (T4). However, the mechanism of this process has not been identified. To clarify the mechanism, we studied adaptive variation of metabolic enzymes involved in T4 turnover. We compared serum T4 turnover rates in thyroidectomized (Tx) rats with or without infusion of active thyroid hormone, triiodothyronine (T3). Furthermore, the levels of mRNA expression and activity of the metabolizing enzymes, deiodinase type 1 (D1), type 2 (D2), uridine diphosphate-glucuronosyltransferase (UGT), and sulfotransferase were also compared in several tissues with or without T3 infusion. After the T3 infusion, the turnover rate of serum T4 in Tx rats returned to normal. Although mRNA expression and activity of D1 decreased significantly in both liver and kidneys without T3 infusion, D2 expression and activity increased markedly in the brain, brown adipose tissue, and skeletal muscle. Surprisingly, hepatic UGT mRNA expression and activity in Tx rats increased significantly in comparison with normal rats, and returned to normal after T3 infusion. This study suggests that repression of the disappearance of serum T4 in rats after Tx is a homeostatic response to decreased serum T3 concentrations. Additionally, T4 glucuronide is a storage form of T4, but may also have biological significance. These results suggest strongly that repression of deiodination of T4 by D1 in the liver and kidneys plays a major role in thyroid hormone homeostasis in Tx rats, and that hepatic UGT also plays a key role in this mechanism. Copyright © 2014 Elsevier Inc. All rights reserved.

Catalytic properties of the archaeal S-adenosylmethionine decarboxylase from Methanococcus jannaschii.

PubMed

Lu, Zichun J; Markham, George D

2004-01-02

S-Adenosylmethionine decarboxylase (AdoMetDC) is a pyruvoyl cofactor-dependent enzyme that participates in polyamine biosynthesis. AdoMetDC from the Archaea Methanococcus jannaschii is a prototype for a recently discovered class that is not homologous to the eucaryotic enzymes or to a distinct group of microbial enzymes. M. jannaschii AdoMetDC has a Km of 95 microm and the turnover number (kcat) of 0.0075 s(-1) at pH 7.5 and 22 degrees C. The turnover number increased approximately 38-fold at a more physiological temperature of 80 degrees C. AdoMetDC was inactivated by treatment with the imine reductant NaCNBH3 only in the presence of substrate. Mass spectrometry of the inactivated protein showed modification solely of the pyruvoyl-containing subunit, with a mass increase corresponding to reduction of a Schiff base adduct with decarboxylated AdoMet. The presteady state time course of the AdoMetDC reaction revealed a burst of product formation; thus, a step after CO2 formation is rate-limiting in turnover. Comparable D2O kinetic isotope effects of were seen on the first turnover (1.9) and on kcat/Km (1.6); there was not a significant D2O isotope effect on kcat, suggesting that product release is rate-limiting in turnover. The pH dependence of the steady state rate showed participation of acid and basic groups with pK values of 5.3 and 8.2 for kcat and 6.5 and 8.3 for kcat/Km, respectively. The competitive inhibitor methylglyoxal bis(guanylhydrazone) binds at a single site per (alphabeta) heterodimer. UV spectroscopic studies show that methylglyoxal bis(guanylhydrazone) binds as the dication with a 23 microm dissociation constant. Studies with substrate analogs show a high specificity for AdoMet.

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.

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.

Cyanobacteria dominance influences resource use efficiency and community turnover in phytoplankton and zooplankton communities.

PubMed

Filstrup, Christopher T; Hillebrand, Helmut; Heathcote, Adam J; Harpole, W Stanley; Downing, John A

2014-04-01

Freshwater biodiversity loss potentially disrupts ecosystem services related to water quality and may negatively impact ecosystem functioning and temporal community turnover. We analysed a data set containing phytoplankton and zooplankton community data from 131 lakes through 9 years in an agricultural region to test predictions that plankton communities with low biodiversity are less efficient in their use of limiting resources and display greater community turnover (measured as community dissimilarity). Phytoplankton resource use efficiency (RUE = biomass per unit resource) was negatively related to phytoplankton evenness (measured as Pielou's evenness), whereas zooplankton RUE was positively related to phytoplankton evenness. Phytoplankton and zooplankton RUE were high and low, respectively, when Cyanobacteria, especially Microcystis sp., dominated. Phytoplankton communities displayed slower community turnover rates when dominated by few genera. Our findings, which counter findings of many terrestrial studies, suggest that Cyanobacteria dominance may play important roles in ecosystem functioning and community turnover in nutrient-enriched lakes. © 2014 John Wiley & Sons Ltd/CNRS.

Sources of variation in extinction rates, turnover, and diversity of marine invertebrate families during the Paleozoic

USGS Publications Warehouse

Nichols, J.D.; Morris, R.W.; Brownie, C.; Pollock, K.H.

1986-01-01

The authors present a new method that can be used to estimate taxonomic turnover in conjunction with stratigraphic range data for families in five phyla of Paleozoic marine invertebrates. Encounter probabilities varied among taxa and showed evidence of a decrease over time for the geologic series examined. The number of families varied substantially among the five phyla and showed some evidence of an increase over the series examined. There was no evidence of variation in extinction probabilities among the phyla. Although there was evidence of temporal variation in extinction probabilities within phyla, there was no evidence of a linear decrease in extinction probabilities over time, as has been reported by others. The authors did find evidence of high extinction probabilities for the two intervals that had been identified by others as periods of mass extinction. They found no evidence of variation in turnover among the five phyla. There was evidence of temporal variation in turnover, with greater turnover occurring in the older series.

An application of Six Sigma methodology to turnover intentions in health care.

PubMed

Taner, Mehmet

2009-01-01

The purpose of this study is to show how the principles of Six Sigma can be applied to the high turnover problem of doctors in medical emergency services and paramedic backup. Six Sigma's define-measure-analyse-improve-control (DMAIC) is applied for reducing the turnover rate of doctors in an organisation operating in emergency services. Variables of the model are determined. Explanatory factor analysis, multiple regression, analysis of variance (ANOVA) and Gage R&R are employed for the analysis. Personal burnout/stress and dissatisfaction from salary were found to be the "vital few" variables. The organisation took a new approach by improving its initiatives to doctors' working conditions. Sigma level of the process is increased. New policy and process changes have been found to effectively decrease the incidence of turnover intentions. The improved process is gained, standardised and institutionalised. This study is one of the few papers in the literature that elaborates the turnover problem of doctors working in the emergency and paramedic backup services.

Systematic analysis of protein turnover in primary cells.

PubMed

Mathieson, Toby; Franken, Holger; Kosinski, Jan; Kurzawa, Nils; Zinn, Nico; Sweetman, Gavain; Poeckel, Daniel; Ratnu, Vikram S; Schramm, Maike; Becher, Isabelle; Steidel, Michael; Noh, Kyung-Min; Bergamini, Giovanna; Beck, Martin; Bantscheff, Marcus; Savitski, Mikhail M

2018-02-15

A better understanding of proteostasis in health and disease requires robust methods to determine protein half-lives. Here we improve the precision and accuracy of peptide ion intensity-based quantification, enabling more accurate protein turnover determination in non-dividing cells by dynamic SILAC-based proteomics. This approach allows exact determination of protein half-lives ranging from 10 to >1000 h. We identified 4000-6000 proteins in several non-dividing cell types, corresponding to 9699 unique protein identifications over the entire data set. We observed similar protein half-lives in B-cells, natural killer cells and monocytes, whereas hepatocytes and mouse embryonic neurons show substantial differences. Our data set extends and statistically validates the previous observation that subunits of protein complexes tend to have coherent turnover. Moreover, analysis of different proteasome and nuclear pore complex assemblies suggests that their turnover rate is architecture dependent. These results illustrate that our approach allows investigating protein turnover and its implications in various cell types.

Monitoring bald eagles using lists of nests: Response to Watts and Duerr

USGS Publications Warehouse

Sauer, John R.; Otto, Mark C.; Kendall, William L.; Zimmerman, Guthrie S.

2011-01-01

The post-delisting monitoring plan for bald eagles (Haliaeetus leucocephalus) roposed use of a dual-frame sample design, in which sampling of known nest sites in combination with additional area-based sampling is used to estimate total number of nesting bald eagle pairs. Watts and Duerr (2010) used data from repeated observations of bald eagle nests in Virginia, USA to estimate a nest turnover rate and used this rate to simulate decline in number of occupied nests in list nests over time. Results of Watts and Duerr suggest that, given the rates of loss of nests from the list of known nest sites in Virginia, the list information will be of little value to sampling unless lists are constantly updated. Those authors criticize the plan for not placing sufficient emphasis on updating and maintaining lists of bald eagle nests. Watts and Duerr's metric of turnover rate does not distinguish detectability or temporary nonuse of nests from permanent loss of nests and likely overestimates turnover rate. We describe a multi-state capture–recapture model that allows appropriate estimation of rates of loss of nests, and we use the model to estimate rates of loss from a sample of nests from Maine, USA. The post-delisting monitoring plan addresses the need to maintain and update the lists of nests, and we show that dual frame sampling is an effective approach for sampling nesting bald eagle populations.

Predicting rates of isotopic turnover across the animal kingdom: a synthesis of existing data.

PubMed

Thomas, Stephen M; Crowther, Thomas W

2015-05-01

The stable isotopes of carbon ((12)C, (13)C) and nitrogen ((14)N, (15)N) represent powerful tools in food web ecology, providing a wide range of dietary information in animal consumers. However, identifying the temporal window over which a consumer's isotopic signature reflects its diet requires an understanding of elemental incorporation, a process that varies from days to years across species and tissue types. Though theory predicts body size and temperature are likely to control incorporation rates, this has not been tested empirically across a morphologically and phylogenetically diverse range of taxa. Readily available estimates of this relationship would, however, aid in the design of stable isotope food web investigations and improve the interpretation of isotopic data collected from natural systems. Using literature-derived turnover estimates from animal species ranging in size from 1 mg to 2000 kg, we develop a predictive tool for stable isotope ecologists, allowing for estimation of incorporation rates in the structural tissues of entirely novel taxa. In keeping with metabolic scaling theory, we show that isotopic turnover rates of carbon and nitrogen in whole organisms and muscle tissue scale allometrically with body mass raised approximately to the power -0.19, an effect modulated by body temperature. This relationship did not, however, apply to incorporation rates in splanchnic tissues, which were instead dependent on the thermoregulation tactic employed by an organism, being considerably faster in endotherms than ectotherms. We believe the predictive turnover equations we provide can improve the design of experiments and interpretation of results obtained in future stable isotopic food web studies. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Evaluation of climate-related carbon turnover processes in global vegetation models for boreal and temperate forests.

PubMed

Thurner, Martin; Beer, Christian; Ciais, Philippe; Friend, Andrew D; Ito, Akihiko; Kleidon, Axel; Lomas, Mark R; Quegan, Shaun; Rademacher, Tim T; Schaphoff, Sibyll; Tum, Markus; Wiltshire, Andy; Carvalhais, Nuno

2017-08-01

Turnover concepts in state-of-the-art global vegetation models (GVMs) account for various processes, but are often highly simplified and may not include an adequate representation of the dominant processes that shape vegetation carbon turnover rates in real forest ecosystems at a large spatial scale. Here, we evaluate vegetation carbon turnover processes in GVMs participating in the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP, including HYBRID4, JeDi, JULES, LPJml, ORCHIDEE, SDGVM, and VISIT) using estimates of vegetation carbon turnover rate (k) derived from a combination of remote sensing based products of biomass and net primary production (NPP). We find that current model limitations lead to considerable biases in the simulated biomass and in k (severe underestimations by all models except JeDi and VISIT compared to observation-based average k), likely contributing to underestimation of positive feedbacks of the northern forest carbon balance to climate change caused by changes in forest mortality. A need for improved turnover concepts related to frost damage, drought, and insect outbreaks to better reproduce observation-based spatial patterns in k is identified. As direct frost damage effects on mortality are usually not accounted for in these GVMs, simulated relationships between k and winter length in boreal forests are not consistent between different regions and strongly biased compared to the observation-based relationships. Some models show a response of k to drought in temperate forests as a result of impacts of water availability on NPP, growth efficiency or carbon balance dependent mortality as well as soil or litter moisture effects on leaf turnover or fire. However, further direct drought effects such as carbon starvation (only in HYBRID4) or hydraulic failure are usually not taken into account by the investigated GVMs. While they are considered dominant large-scale mortality agents, mortality mechanisms related to insects and pathogens are not explicitly treated in these models. © 2017 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Organizational configuration of hospitals succeeding in attracting and retaining nurses.

PubMed

Stordeur, Sabine; D'Hoore, William

2007-01-01

This paper contrasts structural and managerial characteristics of low- and high-turnover hospitals, and describes the organizational configuration of attractive hospitals. In countries facing nurse shortages and turnover, some hospitals succeed in recruiting and retaining nurses. In Magnet Hospitals, managerial practices and environmental characteristics increase nurses' job satisfaction and their commitment to the organization, which in turn decreases nurse turnover. Such an approach suggests that organizations are best understood as clusters of interconnected structures and practices, i.e. organizational configurations rather than entities whose components can be understood in isolation. From a sample of 12 hospitals whose nurse turnover was studied for 1 year, structural and organizational features of hospitals in the first and fourth quartiles, i.e. attractive (turnover <3.1%) vs. conventional (turnover >11.8%) were contrasted. A questionnaire, including perceptions of health-related factors, job demands, stressors, work schedules, organizational climate, and work adjustments antecedent to turnover, was received from 401 nurses working in attractive hospitals (response rate = 53.8%) and 774 nurses in conventional hospitals (response rate = 54.5%). Structural characteristics did not differentiate attractive and conventional hospitals, but employee perceptions towards the organization differed strikingly. Differences were observed for risk exposure, emotional demands, role ambiguity and conflicts, work-family conflicts, effort-reward imbalance and the meaning of work, all in favour of attractive hospitals (P < 0.001). Relationships with nursing management, work ability and satisfaction with working time, handover shifts and schedules were also better in attractive hospitals (P < 0.001). Job satisfaction and commitment were higher in attractive hospitals, whereas burnout and intention to leave were lower (P < 0.001). Organizational characteristics are key factors in nurse attraction and retention. Nurses face difficulties in their work situations, but some hospitals are perceived as healthy organizations. The concept of attractive institutions could serve as a catalyst for improvement in nurses' work environments in Europe.

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

[Nursing workplace bullying and turnover intention: an exploration of associated factors at a medical center in Southern Taiwan].

PubMed

Tsai, Shiau-Ting; Han, Chin-Hua; Chen, Li-Fang; Chou, Fan-Hao

2014-06-01

The chronic shortage of nursing staffs in hospitals continues to increasingly and negatively impact the ability of medical care systems to deliver effective care and ensure the safety of patients. Bullying is one factor known to exacerbate turnover in the nursing workplace. This study explores workplace bullying and turnover intention among nurses working at a medical center in Southern Taiwan. A cross-sectional and correlation research design was conducted using the Negative Acts Questionnaire-Revised (NAQ-R) and the Turnover Intention Questionnaire. A convenience, purposive sample of 708 nurses was recruited. Inclusion criteria included: holding an RN license, able to communicate in both Mandarin and Hokkienese, >6 months of clinical experience, and an NAQ-R score higher than 23. Data were analyzed using SPSS19.0 software. Approximately 85% of participants had experienced some degree of workplace bullying during the previous 6-month period. The trend of the turnover intention tended to the right at a high degree. A moderate, positive, and significant correlation was found between turnover intention and bullying total scores (r=.39, p<.05). Multiple regression showed bullying as the most important predicator of turnover intention (15.10%). Based on our findings, we suggest that nurses should enhance their awareness of the negative consequences of workplace bullying. Furthermore, hospitals should implement appropriate mechanisms to decrease the phenomenon of inter-staff bullying, improve the nursing workplace environment, and reduce the rate of turnover intention.

Measurement of the rates of oxindole-3-acetic acid turnover, and indole-3-acetic acid oxidation in Zea mays seedlings

NASA Technical Reports Server (NTRS)

Nonhebel, H. M.; Bandurski, R. S. (Principal Investigator)

1986-01-01

Oxindole-3-acetic acid is the principal catabolite of indole-3-acetic acid in Zea mays seedlings. In this paper measurements of the turnover of oxindole-3-acetic acid are presented and used to calculate the rate of indole-3-acetic acid oxidation. [3H]Oxindole-3-acetic acid was applied to the endosperm of Zea mays seedlings and allowed to equilibrate for 24 h before the start of the experiment. The subsequent decrease in its specific activity was used to calculate the turnover rate. The average half-life of oxindole-3-acetic acid in the shoots was found to be 30 h while that in the kernels had an average half-life of 35h. Using previously published values of the pool sizes of oxindole-3-acetic acid in shoots and kernels from seedlings of the same age and variety, and grown under the same conditions, the rate of indole-3-acetic acid oxidation was calculated to be 1.1 pmol plant-1 h-1 in the shoots and 7.1 pmol plant-1 h-1 in the kernels.

Long-term trends in a Dimictic Lake

USGS Publications Warehouse

Robertson, Dale M.; Hsieh, Yi-Fang; Lathrop, Richard C; Wu, Chin H; Magee, Madeline; Hamilton, David P.

2016-01-01

 The one-dimensional hydrodynamic ice model, DYRESM-WQ-I, was modified to simulate ice cover and thermal structure of dimictic Lake Mendota, Wisconsin, USA, over a continuous 104-year period (1911–2014). The model results were then used to examine the drivers of changes in ice cover and water temperature, focusing on the responses to shifts in air temperature, wind speed, and water clarity at multiyear timescales. Observations of the drivers include a change in the trend of warming air temperatures from 0.081 °C per decade before 1981 to 0.334 °C per decade thereafter, as well as a shift in mean wind speed from 4.44 m s−1 before 1994 to 3.74 m s−1 thereafter. Observations show that Lake Mendota has experienced significant changes in ice cover: later ice-on date(9.0 days later per century), earlier ice-off date (12.3 days per century), decreasing ice cover duration (21.3 days per century), while model simulations indicate a change in maximum ice thickness (12.7 cm decrease per century). Model simulations also show changes in the lake thermal regime of earlier stratification onset (12.3 days per century), later fall turnover (14.6 days per century), longer stratification duration (26.8 days per century), and decreasing summer hypolimnetic temperatures (−1.4 °C per century). Correlation analysis of lake variables and driving variables revealed ice cover variables, stratification onset, epilimnetic temperature, and hypolimnetic temperature were most closely correlated with air temperature, whereas freeze-over water temperature, hypolimnetic heating, and fall turnover date were more closely correlated with wind speed. Each lake variable (i.e., ice-on and ice-off dates, ice cover duration, maximum ice thickness, freeze-over water temperature, stratification onset, fall turnover date, stratification duration, epilimnion temperature, hypolimnion temperature, and hypolimnetic heating) was averaged for the three periods (1911–1980, 1981–1993, and 1994–2014) delineated by abrupt changes in air temperature and wind speed. Average summer hypolimnetic temperature and fall turnover date exhibit significant differences between the third period and the first two periods. Changes in ice cover (ice-on and ice-off dates, ice cover duration, and maximum ice thickness) exhibit an abrupt change after 1994, which was related in part to the warm El Niño winter of 1997–1998. Under-ice water temperature, freeze-over water temperature, hypolimnetic temperature, fall turnover date, and stratification duration demonstrate a significant difference in the third period (1994–2014), when air temperature was warmest and wind speeds decreased rather abruptly. The trends in ice cover and water temperature demonstrate responses to both long-term and abrupt changes in meteorological conditions that can be complemented with numerical modeling to better understand how these variables will respond in a future climate.

Teacher Retention in a Small Rural School as Related to Job Satisfaction and Student Performance

ERIC Educational Resources Information Center

Dykstra, Dirk D.

2014-01-01

Reductions in student performance and increased non-instructional costs have been found to be direct results of high teacher turnover. In one district in the southern United States, the teacher turnover rate was almost 3 times the state average, prompting administrators to adjust local policies and procedures. The purpose of this project study was…

Teacher Retention at Low-Performing Schools. Using the Evidence

ERIC Educational Resources Information Center

SERVE Center for Continuous Improvement at UNCG, 2006

2006-01-01

In 2004-2005, North Carolina's average teacher turnover rate was nearly 13 percent, ranging from a high of 29 percent to a low of 4 percent. Turnover among teachers in low-performing schools was substantially higher, with a low of 12 percent and a high of 57 percent. North Carolina has put strategies in place to address teacher retention but how…

Can Good Principals Keep Teachers in Disadvantaged Schools? Linking Principal Effectiveness to Teacher Satisfaction and Turnover in Hard-to-Staff Environments

ERIC Educational Resources Information Center

Grissom, Jason A.

2011-01-01

Background: High rates of teacher turnover likely mean greater school instability, disruption of curricular cohesiveness, and a continual need to hire inexperienced teachers, who typically are less effective, as replacements for teachers who leave. Unfortunately, research consistently finds that teachers who work in schools with large numbers of…

Intentions to Quit Work among Care Staff Working in the Aged Care Sector

ERIC Educational Resources Information Center

Karantzas, Gery C.; Mellor, David; McCabe, Marita P.; Davison, Tanya E.; Beaton, Paul; Mrkic, Dejan

2012-01-01

Purpose of the Study: The aged care industry experiences high rates of staff turnover. Staff turnover has significant implications for the quality of care provided to care recipients and the financial costs to care agencies. In this study, we applied a model of intention to quit to identify the contextual and personal factors that shape aged care…

The Changing of the Guard: Turnover and Structural Change in the Top-Management Positions.

ERIC Educational Resources Information Center

Harrison, J. Richard; And Others

1988-01-01

Using transition-rate analysis for a sample of 671 large U.S. manufacturing firms during 1978-1980, this paper explores the nature and relationship of the chief executive officer (CEO) and chair of the board of directors positions. One analysis examines CEO and board chair turnover; the other examines consolidations and separations. Includes 46…

Species Turnover through Time: Colonization and Extinction Dynamics across Metacommunities.

PubMed

Nuvoloni, Felipe Micali; Feres, Reinaldo José Fazzio; Gilbert, Benjamin

2016-06-01

Island biogeography and metacommunity theory often use equilibrium assumptions to predict local diversity, yet nonequilibrium dynamics are common in nature. In nonequilibrium communities, local diversity fluctuates through time as the relative importance of colonization and extinction change. Here, we test the prevalence and causes of nonequilibrium dynamics in metacommunities of mites associated with rubber trees distributed over large spatial (>1,000 km) and temporal (>30-60 generations) scales in Brazil. We measured colonization and extinction rates to test species turnover and nonequilibrium dynamics over a growing season. Mite metacommunities exhibited nonequilibrium dynamics for most months of the year, and these dynamics tracked climatic conditions. Monthly shifts in temperature of more than 1°C resulted in nonequilibrium dynamics, as did mean temperatures outside of two critical ranges. Nonequilibrium dynamics were caused by a change in colonization with temperature change and changes in both colonization and extinction with absolute temperature. Species turnover showed different trends; high relative humidity increased both colonization and extinction rates, increasing turnover but not nonequilibrium dynamics. Our study illustrates that testing nonequilibrium dynamics can provide new insights into the drivers of colonization, extinction, and diversity fluctuations in metacommunities.

High turnover in a photocatalytic system for water reduction to produce hydrogen using a Ru,  Rh,  Ru photoinitiated electron collector.

PubMed

Arachchige, Shamindri M; Shaw, Ryan; White, Travis A; Shenoy, Vimal; Tsui, Hei-Man; Brewer, Karen J

2011-04-18

Covalent coupling of Ru(II) light absorbers to a Rh(III) electron collecting site through polyazine bridging ligands affords photocatalytic production of H(2) in the presence of visible light and a sacrificial electron donor. A robust photocatalytic system displaying a high turnover of the photocatalyst has been developed using the photoinitiated electron collector [{(bpy)(2)Ru(dpp)}(2)RhBr(2)](5+) (bpy=2,2'-bipyridine; dpp=2,3-bis(2-pyridyl)pyrazine) and N,N-dimethylaniline in DMF/H(2)O. Studies have shown that increased [DMA], the headspace volume, and the use of DMF solvent improves the systems performance and stability providing mechanistic insight into the deactivation routes of the photocatalytic system. Photolysis of the system at 460 nm generates 20 mL of H(2) in 19.5 h with a maximum Φ=0.023 based on H(2) produced and an overall Φ=0.014 and 280 turnovers of the photocatalyst. The photocatalytic system also displays long-term photostability with 30 mL of H(2) generated and 420 turnovers in 50 h under the same conditions. Prolonged photolysis provides 820 mol H(2) per mole of catalyst. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exit interviews to reduce turnover amongst healthcare professionals.

PubMed

Flint, Anndrea; Webster, Joan

2013-03-28

Exit interviews are widely used in healthcare organisations to identify reasons for staff attrition, yet their usefulness in limiting turnover is unclear. To determine the effectiveness of various exit interview strategies in decreasing turnover rates amongst healthcare professionals. We searched the Cochrane EPOC Group Specialised Register; Cochrane Central Register of Controlled Trials (CENTRAL), Issue 11, 2012; MEDLINE, Ovid (1950- ); EMBASE, Ovid (1947- ); CINAHL, EbscoHost (1980- ), and PsycINFO, OVID (1806-) between October 31 and November 6, 2012. We also screened the reference lists of included studies and relevant reviews; and searched trial registries for planned and on-going trials. We did not restrict searches by language or publication date. Randomised controlled trials, controlled clinical trials, controlled before-after studies and interrupted time series studies comparing turnover rates between healthcare professionals who had undergone one form of exit interview with another form of exit interview or with no interview. Two review authors independently assessed trial quality and extracted data. The original search identified 1560 citations, of which we considered 19 potentially relevant. The two authors independently reviewed the abstracts of these studies and retrieved the full texts of eight studies. We excluded all eight following independent assessment; they were either interviews, commentaries on how to do an exit interview or descriptive studies about reasons for leaving. We found no trials that matched our inclusion criteria. For this first update, we screened 2220 citations and identified no new trials. Evidence about the effectiveness of exit interviews to reduce turnover is currently not available. However, exit interviews may provide useful information about the work environment which, in turn, may be useful in the development of interventions to reduce turnover.

Exit interviews to reduce turnover amongst healthcare professionals.

PubMed

Webster, Joan; Flint, Anndrea

2014-03-15

Exit interviews are widely used in healthcare organisations to identify reasons for staff attrition, yet their usefulness in limiting turnover is unclear. To determine the effectiveness of various exit interview strategies in decreasing turnover rates amongst healthcare professionals. We searched the Cochrane EPOC Group Specialised Register; Cochrane Central Register of Controlled Trials (CENTRAL), Issue 11, 2012; MEDLINE, Ovid (1950- ); EMBASE, Ovid (1947- ); CINAHL, EbscoHost (1980- ), and PsycINFO, OVID (1806-) between October 31 and November 6, 2012. We also screened the reference lists of included studies and relevant reviews; and searched trial registries for planned and on-going trials. We did not restrict searches by language or publication date. Randomised controlled trials, controlled clinical trials, controlled before-after studies and interrupted time series studies comparing turnover rates between healthcare professionals who had undergone one form of exit interview with another form of exit interview or with no interview. Two review authors independently assessed trial quality and extracted data. The original search identified 1560 citations, of which we considered 19 potentially relevant. The two authors independently reviewed the abstracts of these studies and retrieved the full texts of eight studies. We excluded all eight following independent assessment; they were either interviews, commentaries on how to do an exit interview or descriptive studies about reasons for leaving. We found no trials that matched our inclusion criteria. For this first update, we screened 2220 citations and identified no new trials. Evidence about the effectiveness of exit interviews to reduce turnover is currently not available. However, exit interviews may provide useful information about the work environment which, in turn, may be useful in the development of interventions to reduce turnover.

Exit interviews to reduce turnover amongst healthcare professionals.

PubMed

Webster, Joan; Flint, Anndrea

2014-08-19

Exit interviews are widely used in healthcare organisations to identify reasons for staff attrition, yet their usefulness in limiting turnover is unclear. To determine the effectiveness of various exit interview strategies in decreasing turnover rates amongst healthcare professionals. We searched the Cochrane EPOC Group Specialised Register; Cochrane Central Register of Controlled Trials (CENTRAL), Issue 11, 2012; MEDLINE, Ovid (1950- ); EMBASE, Ovid (1947- ); CINAHL, EbscoHost (1980- ), and PsycINFO, OVID (1806-) between October 31 and November 6, 2012. We also screened the reference lists of included studies and relevant reviews; and searched trial registries for planned and on-going studies. We did not restrict searches by language or publication date. Randomised controlled trials, controlled clinical trials, controlled before-after studies and interrupted time series studies comparing turnover rates between healthcare professionals who had undergone one form of exit interview with another form of exit interview or with no interview. Two review authors independently assessed trial quality and extracted data. The original search identified 1560 citations, of which we considered 19 potentially relevant. The two authors independently reviewed the abstracts of these studies and retrieved the full texts of eight studies. We excluded all eight following independent assessment; they were either interviews, commentaries on how to do an exit interview or descriptive studies about reasons for leaving. We found no studies that matched our inclusion criteria. For this first update, we screened 2220 citations and identified no new studies. Evidence about the effectiveness of exit interviews to reduce turnover is currently not available. However, exit interviews may provide useful information about the work environment which, in turn, may be useful in the development of interventions to reduce turnover.

DeuteRater: a tool for quantifying peptide isotope precision and kinetic proteomics.

PubMed

Naylor, Bradley C; Porter, Michael T; Wilson, Elise; Herring, Adam; Lofthouse, Spencer; Hannemann, Austin; Piccolo, Stephen R; Rockwood, Alan L; Price, John C

2017-05-15

Using mass spectrometry to measure the concentration and turnover of the individual proteins in a proteome, enables the calculation of individual synthesis and degradation rates for each protein. Software to analyze concentration is readily available, but software to analyze turnover is lacking. Data analysis workflows typically don't access the full breadth of information about instrument precision and accuracy that is present in each peptide isotopic envelope measurement. This method utilizes both isotope distribution and changes in neutromer spacing, which benefits the analysis of both concentration and turnover. We have developed a data analysis tool, DeuteRater, to measure protein turnover from metabolic D 2 O labeling. DeuteRater uses theoretical predictions for label-dependent change in isotope abundance and inter-peak (neutromer) spacing within the isotope envelope to calculate protein turnover rate. We have also used these metrics to evaluate the accuracy and precision of peptide measurements and thereby determined the optimal data acquisition parameters of different instruments, as well as the effect of data processing steps. We show that these combined measurements can be used to remove noise and increase confidence in the protein turnover measurement for each protein. Source code and ReadMe for Python 2 and 3 versions of DeuteRater are available at https://github.com/JC-Price/DeuteRater . Data is at https://chorusproject.org/pages/index.html project number 1147. Critical Intermediate calculation files provided as Tables S3 and S4. Software has only been tested on Windows machines. jcprice@chem.byu.edu. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

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).

Developing human capital: what is the impact on nurse turnover?

PubMed

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

2009-09-01

To investigate the impact that increasing human capital through staff training makes on the voluntary turnover of registered nurses. Healthcare organizations in Canada, the United Kingdom, the United States, and Australia are experiencing turbulent nursing labour markets characterized by extreme staff shortages and high levels of turnover. Organizations that invest in the development of their nursing human resources may be able to mitigate high turnover through the creation of conditions that more effectively develop and utilize their existing human capital. A questionnaire was sent to the chief nursing officers of 2208 hospitals and long-term care facilities in every province and territory of Canada yielding a response rate of 32.3%. The analysis featured a three-step hierarchical regression with two sets of control variables. After controlling for establishment demographics and local labour market conditions, perceptions of nursing human capital and the level of staff training provided were modestly associated with lower levels of establishment turnover. and implications for Nursing Management The results suggest that healthcare organizations that have made greater investments in their nursing human capital are more likely to demonstrate lower levels of turnover of their registered nursing personnel.

Organic matter and nutrients associated with fine root turnover in a white oak stand. [Quercus albus

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

Joslin, J.D.; Henderson, G.S.

1987-06-01

Organic matter and nutrients cycled by fine root turnover were quantified in a mature white oak (Quercus alba L.) stand and compared to contributions from litterfall. The budget method, a revised version of the traditional repeated sampling method, was used to measure root turnover. The magnitude of the live and dead pools of three size classes of fine (<5 mm diameter) roots were monitored bimonthly for 14 months. Decomposition rates over these intervals were also measured, while production and mortality were calculated. Litterfall was collected simultaneously, and the nutrient concentrations of the various detritus components determined. Root pools fluctuated less,more » and total root turnover biomass (220 g m/sup -2/ yr/sup -1/) was also less than previously noted in most other stands studied. Fine root turnover accounted for 30% of the total detritus production and 20-40% of the turnover of the five macronutrients (N, P, K, Ca, Mg) studied. Differences with previous studies suggest that there may be rather large species and/or site-related differences in the amount of energy various stands allocate for fine root maintenance. For. Sci. 33(2):330-346.« less

Turnover of galactans and other cell wall polysaccharides during development of flax plants

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

Gorshkova, T.A.; Chemikosova, S.B.; Lozovaya, V.V.

1997-06-01

We investigated the synthesis and turnover of cell wall polysaccharides of the flax (Linum usitatissimum L.) plant during development of the phloem fibers. One-month-old flax plants were exposed to a 40-min pulse with {sup 14}CO{sub 2} followed by 8-h, 24-h, and 1-month periods of chase with ambient CO{sub 2}, and radioactivity in cell wall sugars was determined in various plant parts. The relative radioactivity of glucose in noncellulosic polysaccharides was the highest compared with all other cell wall sugars immediately after the pulse and decreased substantially during the subsequent chase. The relative radioactivities of the other cell wall sugars changedmore » with differing rates, indicating turnover of specific polysaccharides. Notably, after 1 month of chase there was a marked decrease in the proportional mass and total radioactivity in cell wall galactose, indicating a long-term turnover of the galactans enriched in the fiber-containing tissues. The ratio of radiolabeled xylose to arabinose also increased during the chase, indicating a turnover of arabinose-containing polymers and interconversion to xylose. The pattern of label redistribution differed between organs, indicating that the cell wall turnover processes are tissue- and cell-specific.« less

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.

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

Improved arrival-date estimates of Arctic-breeding Dunlin (Calidris alpina arcticola)

USGS Publications Warehouse

Doll, Andrew C.; Lanctot, Richard B.; Stricker, Craig A.; Yezerinac, Stephen M.; Wunder, Michael B.

2015-01-01

The use of stable isotopes in animal ecology depends on accurate descriptions of isotope dynamics within individuals. The prevailing assumption that laboratory-derived isotopic parameters apply to free-living animals is largely untested. We used stable carbon isotopes (δ13C) in whole blood from migratory Dunlin (Calidris alpina arcticola) to estimate an in situ turnover rate and individual diet-switch dates. Our in situ results indicated that turnover rates were higher in free-living birds, in comparison to the results of an experimental study on captive Dunlin and estimates derived from a theoretical allometric model. Diet-switch dates from all 3 methods were then used to estimate arrival dates to the Arctic; arrival dates calculated with the in situ turnover rate were later than those with the other turnover-rate estimates, substantially so in some cases. These later arrival dates matched dates when local snow conditions would have allowed Dunlin to settle, and agreed with anticipated arrival dates of Dunlin tracked with light-level geolocators. Our study presents a novel method for accurately estimating arrival dates for individuals of migratory species in which return dates are difficult to document. This may be particularly appropriate for species in which extrinsic tracking devices cannot easily be employed because of cost, body size, or behavioral constraints, and in habitats that do not allow individuals to be detected easily upon first arrival. Thus, this isotopic method offers an exciting alternative approach to better understand how species may be altering their arrival dates in response to changing climatic conditions.

Feasibility of simultaneous measurement of bone formation and bone resorption markers to assess bone turnover rate in postmenopausal women: an EPOLOS study.

PubMed

Łukaszkiewicz, Jacek; Karczmarewicz, Elzbieta; Płudowski, Paweł; Jaworski, Maciej; Czerwiński, Edward; Lewiński, Andrzej; Marcinowska-Suchowierska, Ewa; Milewicz, Andrzej; Spaczyński, Marek; Lorenc, Roman S

2008-12-01

One of the most important risk factors for osteoporotic fractures in postmenopausal women is elevated bone turnover (EBT), occurring in 25-30% of this population. This study's aim was to find a correlation between bone resorption and bone formation markers to assess bone turnover rate and qualify an individual postmenopausal woman as a possible EBT subject. Three hundred twenty postmenopausal women (> or = one year after the last menstruation, < or = 70 years old) were enrolled at seven clinical sites in this cross-sectional observational study conducted within the EPOLOS. The group was a random sample of the population. The study was performed in a referral center involved in the diagnosis and treatment of osteoporosis. The exclusion criteria included pregnancy, cancer, fracture in the last year, and overweight (> 100 kg). Bone mineral density (BMD) measurements of the lumbar spine, total hip, trochanter, and femoral neck regions were performed. Bone resorption and formation rates were evaluated by serum levels of C-terminal telopeptide of type I collagen (CTX) and osteocalcin (OC), respectively. Using logistic regression to correlate the concentrations of CTX and OC it was possible not only to distinguish the EBT subgroup, but also to construct a simple nomogram for easy classification of individual patients as possible EBT subjects. EBT patients showed generally decreased BMD values and increased bone formation and resorption rates. Evaluation of both CTX and OC levels enables a more proper indication for EBT. The proposed nomogram may assist in evaluating outcome from the two markers of bone turnover.

A STUDY OF EMPLOYMENT OPPORTUNITIES AND TRAINING NEEDS IN OFF-FARM AGRICULTURAL OCCUPATIONS IN OKLAHOMA.

ERIC Educational Resources Information Center

STEVENSON, WILLIAM W.

THE PURPOSE OF THE STUDY WAS TO IDENTIFY PRESENT AND EMERGING OFF-FARM AGRICULTURAL OCCUPATIONS, THE NUMBER OF EMPLOYEES, TURNOVER AND JOB OPPORTUNITIES, NEED FOR AGRICULTURAL COMPETENCIES, BEGINNING AND MAXIMUM SALARIES, AGE FOR JOB ENTRY EDUCATION, AND SO FORTH. THERE WERE 1,879 MAJOR BUSINESSES CONSIDERED TO BE AGRICULTURALLY RELATED, AND 719…

Relaxation in two dimensions and the 'sinh-Poisson' equation

NASA Technical Reports Server (NTRS)

Montgomery, D.; Matthaeus, W. H.; Stribling, W. T.; Martinez, D.; Oughton, S.

1992-01-01

Long-time states of a turbulent, decaying, two-dimensional, Navier-Stokes flow are shown numerically to relax toward maximum-entropy configurations, as defined by the "sinh-Poisson" equation. The large-scale Reynolds number is about 14,000, the spatial resolution is (512)-squared, the boundary conditions are spatially periodic, and the evolution takes place over nearly 400 large-scale eddy-turnover times.

Stepwise onset of the Icehouse world and its impact on Oligo-Miocene Central Asian mammals

NASA Astrophysics Data System (ADS)

Harzhauser, Mathias; Daxner-Höck, Gudrun; López-Guerrero, Paloma; Maridet, Olivier; Oliver, Adriana; Piller, Werner E.; Richoz, Sylvain; Erbajeva, Margarita A.; Neubauer, Thomas A.; Göhlich, Ursula B.

2016-11-01

Central Asia is a key area to study the impact of Cenozoic climate cooling on continental ecosystems. One of the best places to search for rather continuous paleontological records is the Valley of Lakes in Mongolia with its outstandingly fossil-rich Oligocene and Miocene terrestrial sediments. Here, we investigate the response by mammal communities during the early stage of Earth’s icehouse climate in Central Asia. Based on statistical analyses of occurrence and abundance data of 18608 specimens representing 175 mammal species and geochemical (carbon isotopes) and geophysical (magnetic susceptibility) data we link shifts in diversities with major climatic variations. Our data document for the first time that the post-Eocene aridification of Central Asia happened in several steps, was interrupted by short episodes of increased precipitation, and was not a gradual process. We show that the timing of the major turnovers in Oligocene mammal communities is tightly linked with global climate events rather than slow tectonics processes. The most severe decline of up 48% of total diversity is related to aridification during the maximum of the Late Oligocene Warming at 25 Ma. Its magnitude was distinctly larger than the community turnover linked to the mid-Oligocene Glacial Maximum.

Stepwise onset of the Icehouse world and its impact on Oligo-Miocene Central Asian mammals.

PubMed

Harzhauser, Mathias; Daxner-Höck, Gudrun; López-Guerrero, Paloma; Maridet, Olivier; Oliver, Adriana; Piller, Werner E; Richoz, Sylvain; Erbajeva, Margarita A; Neubauer, Thomas A; Göhlich, Ursula B

2016-11-29

Central Asia is a key area to study the impact of Cenozoic climate cooling on continental ecosystems. One of the best places to search for rather continuous paleontological records is the Valley of Lakes in Mongolia with its outstandingly fossil-rich Oligocene and Miocene terrestrial sediments. Here, we investigate the response by mammal communities during the early stage of Earth's icehouse climate in Central Asia. Based on statistical analyses of occurrence and abundance data of 18608 specimens representing 175 mammal species and geochemical (carbon isotopes) and geophysical (magnetic susceptibility) data we link shifts in diversities with major climatic variations. Our data document for the first time that the post-Eocene aridification of Central Asia happened in several steps, was interrupted by short episodes of increased precipitation, and was not a gradual process. We show that the timing of the major turnovers in Oligocene mammal communities is tightly linked with global climate events rather than slow tectonics processes. The most severe decline of up 48% of total diversity is related to aridification during the maximum of the Late Oligocene Warming at 25 Ma. Its magnitude was distinctly larger than the community turnover linked to the mid-Oligocene Glacial Maximum.

Network Modeling of Adult Neurogenesis: Shifting Rates of Neuronal Turnover Optimally Gears Network Learning according to Novelty Gradient

PubMed Central

Chambers, R. Andrew; Conroy, Susan K.

2010-01-01

Apoptotic and neurogenic events in the adult hippocampus are hypothesized to play a role in cognitive responses to new contexts. Corticosteroid-mediated stress responses and other neural processes invoked by substantially novel contextual changes may regulate these processes. Using elementary three-layer neural networks that learn by incremental synaptic plasticity, we explored whether the cognitive effects of differential regimens of neuronal turnover depend on the environmental context in terms of the degree of novelty in the new information to be learned. In “adult” networks that had achieved mature synaptic connectivity upon prior learning of the Roman alphabet, imposition of apoptosis/neurogenesis before learning increasingly novel information (alternate Roman < Russian < Hebrew) reveals optimality of informatic cost benefits when rates of turnover are geared in proportion to the degree of novelty. These findings predict that flexible control of rates of apoptosis–neurogenesis within plastic, mature neural systems optimizes learning attributes under varying degrees of contextual change, and that failures in this regulation may define a role for adult hippocampal neurogenesis in novelty- and stress-responsive psychiatric disorders. PMID:17214558

Network modeling of adult neurogenesis: shifting rates of neuronal turnover optimally gears network learning according to novelty gradient.

PubMed

Chambers, R Andrew; Conroy, Susan K

2007-01-01

Apoptotic and neurogenic events in the adult hippocampus are hypothesized to play a role in cognitive responses to new contexts. Corticosteroid-mediated stress responses and other neural processes invoked by substantially novel contextual changes may regulate these processes. Using elementary three-layer neural networks that learn by incremental synaptic plasticity, we explored whether the cognitive effects of differential regimens of neuronal turnover depend on the environmental context in terms of the degree of novelty in the new information to be learned. In "adult" networks that had achieved mature synaptic connectivity upon prior learning of the Roman alphabet, imposition of apoptosis/neurogenesis before learning increasingly novel information (alternate Roman < Russian < Hebrew) reveals optimality of informatic cost benefits when rates of turnover are geared in proportion to the degree of novelty. These findings predict that flexible control of rates of apoptosis-neurogenesis within plastic, mature neural systems optimizes learning attributes under varying degrees of contextual change, and that failures in this regulation may define a role for adult hippocampal neurogenesis in novelty- and stress-responsive psychiatric disorders.

UCHL3 Regulates Topoisomerase-Induced Chromosomal Break Repair by Controlling TDP1 Proteostasis.

PubMed

Liao, Chunyan; Beveridge, Ryan; Hudson, Jessica J R; Parker, Jacob D; Chiang, Shih-Chieh; Ray, Swagat; Ashour, Mohamed E; Sudbery, Ian; Dickman, Mark J; El-Khamisy, Sherif F

2018-06-12

Genomic damage can feature DNA-protein crosslinks whereby their acute accumulation is utilized to treat cancer and progressive accumulation causes neurodegeneration. This is typified by tyrosyl DNA phosphodiesterase 1 (TDP1), which repairs topoisomerase-mediated chromosomal breaks. Although TDP1 levels vary in multiple clinical settings, the mechanism underpinning this variation is unknown. We reveal that TDP1 is controlled by ubiquitylation and identify UCHL3 as the deubiquitylase that controls TDP1 proteostasis. Depletion of UCHL3 increases TDP1 ubiquitylation and turnover rate and sensitizes cells to TOP1 poisons. Overexpression of UCHL3, but not a catalytically inactive mutant, suppresses TDP1 ubiquitylation and turnover rate. TDP1 overexpression in the topoisomerase therapy-resistant rhabdomyosarcoma is driven by UCHL3 overexpression. In contrast, UCHL3 is downregulated in spinocerebellar ataxia with axonal neuropathy (SCAN1), causing elevated levels of TDP1 ubiquitylation and faster turnover rate. These data establish UCHL3 as a regulator of TDP1 proteostasis and, consequently, a fine-tuner of protein-linked DNA break repair. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Quantification of isotopic turnover in agricultural systems

NASA Astrophysics Data System (ADS)

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

2012-04-01

The isotopic turnover, which is a proxy for the metabolic rate, is gaining scientific importance. It is quantified for an increasing range of organisms, from microorganisms over plants to animals including agricultural livestock. Additionally, the isotopic turnover is analyzed on different scales, from organs to organisms to ecosystems and even to the biosphere. In particular, the quantification of the isotopic turnover of specific tissues within the same organism, e.g. organs like liver and muscle and products like milk and faeces, has brought new insights to improve understanding of nutrient cycles and fluxes, respectively. Thus, the knowledge of isotopic turnover is important in many areas, including physiology, e.g. milk synthesis, ecology, e.g. soil retention time of water, and medical science, e.g. cancer diagnosis. So far, the isotopic turnover is quantified by applying time, cost and expertise intensive tracer experiments. Usually, this comprises two isotopic equilibration periods. A first equilibration period with a constant isotopic input signal is followed by a second equilibration period with a distinct constant isotopic input signal. This yields a smooth signal change from the first to the second signal in the object under consideration. This approach reveals at least three major problems. (i) The input signals must be controlled isotopically, which is almost impossible in many realistic cases like free ranging animals. (ii) Both equilibration periods may be very long, especially when the turnover rate of the object under consideration is very slow, which aggravates the first problem. (iii) The detection of small or slow pools is improved by large isotopic signal changes, but large isotopic changes also involve a considerable change in the input material; e.g. animal studies are usually carried out as diet-switch experiments, where the diet is switched between C3 and C4 plants, since C3 and C4 plants differ strongly in their isotopic signal. The additional change in nutrition induces changes in physiology that are likely to bias the estimation of the isotopic turnover. We designed an experiment with lactating cows which were successively exposed to the diet's natural isotopic variation and a diet-switch. We examined whether the same turnover information can be obtained from the natural (uncontrolled, short-term) isotopic variation as from the diet-switch experiment. Statistical methods to retrieve the turnover characteristics comprised multi-pool compartmental modeling for the diet-switch experiment as well as correlation analysis to perform wiggle-matching and quantification of autocorrelation (geostatistics) for the analysis of the natural variation. All three methods yielded similar results but differed in their strengths and weaknesses that will be highlighted. Combining the strengths of the new methods can make this tool even more advantageous than diet-switch experiments in many cases. In particular, the new approach empowers studying isotope turnover under a wider range of keepings, wildlife conditions and species, yielding turnover estimates that are not biased by changes in nutrition.

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

Genomic-scale measurement of mRNA turnover and the mechanisms of action of the anti-cancer drug flavopiridol.

PubMed

Lam, L T; Pickeral, O K; Peng, A C; Rosenwald, A; Hurt, E M; Giltnane, J M; Averett, L M; Zhao, H; Davis, R E; Sathyamoorthy, M; Wahl, L M; Harris, E D; Mikovits, J A; Monks, A P; Hollingshead, M G; Sausville, E A; Staudt, L M

2001-01-01

Flavopiridol, a flavonoid currently in cancer clinical trials, inhibits cyclin-dependent kinases (CDKs) by competitively blocking their ATP-binding pocket. However, the mechanism of action of flavopiridol as an anti-cancer agent has not been fully elucidated. Using DNA microarrays, we found that flavopiridol inhibited gene expression broadly, in contrast to two other CDK inhibitors, roscovitine and 9-nitropaullone. The gene expression profile of flavopiridol closely resembled the profiles of two transcription inhibitors, actinomycin D and 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB), suggesting that flavopiridol inhibits transcription globally. We were therefore able to use flavopiridol to measure mRNA turnover rates comprehensively and we found that different functional classes of genes had distinct distributions of mRNA turnover rates. In particular, genes encoding apoptosis regulators frequently had very short half-lives, as did several genes encoding key cell-cycle regulators. Strikingly, genes that were transcriptionally inducible were disproportionately represented in the class of genes with rapid mRNA turnover. The present genomic-scale measurement of mRNA turnover uncovered a regulatory logic that links gene function with mRNA half-life. The observation that transcriptionally inducible genes often have short mRNA half-lives demonstrates that cells have a coordinated strategy to rapidly modulate the mRNA levels of these genes. In addition, the present results suggest that flavopiridol may be more effective against types of cancer that are highly dependent on genes with unstable mRNAs.

Calcareous nannofossil assemblage changes across the Paleocene-Eocene thermal maximum: Evidence from a shelf setting

USGS Publications Warehouse

Self-Trail, Jean M.; Powars, David S.; Watkins, David K.; Wandless, Gregory A.

2012-01-01

Biotic response of calcareous nannoplankton to abrupt warming across the Paleocene/Eocene boundary reflects a primary response to climatically induced parameters including increased continental runoff of freshwater, global acidification of seawater, high sedimentation rates, and calcareous nannoplankton assemblage turnover. We identify ecophenotypic nannofossil species adapted to low pH conditions (Discoaster anartios, D. araneus, Rhomboaster spp.), excursion taxa adapted to the extremely warm climatic conditions (Bomolithus supremus and Coccolithus bownii), three species of the genus Toweius (T. serotinus, T. callosus, T. occultatus) adapted to warm, rather than cool, water conditions, opportunists adapted to high productivity conditions (Coronocyclus bramlettei, Neochiastozygus junctus), and species adapted to oligotropic and/or cool‐water conditions that went into refugium during the PETM (Zygrablithus bijugatus, Calcidiscus? parvicrucis and Chiasmolithus bidens). Discoaster anartios was adapted to meso- to eutrophic, rather than oligotrophic, conditions. Comparison of these data to previous work on sediments deposited on shelf settings suggests that local conditions such as high precipitation rates and possible increase in major storms such as hurricanes resulted in increased continental runoff and high sedimentation rates that affected assemblage response to the PETM.

Continuous measurement of galactolipid hydrolysis by pancreatic lipolytic enzymes using the pH-stat technique and a medium chain monogalactosyl diglyceride as substrate.

PubMed

Amara, Sawsan; Lafont, Dominique; Fiorentino, Brice; Boullanger, Paul; Carrière, Frédéric; De Caro, Alain

2009-10-01

Galactolipids are the main lipids from plants and galactolipases play a major role in their metabolism. These enzymes were however poorly studied so far and only few assays have been developed. A specific and continuous galactolipase assay using synthetic medium chain monogalactosyl diacylglycerol (MGDG) as substrate was developed using the pH-stat technique and recombinant human (rHPLRP2) and guinea pig (rGPLRP2) pancreatic lipase-related protein 2 as model enzymes. PLRP2s are the main enzymes involved in the digestion of galactolipids in the gastrointestinal tract. Monogalactosyl di-octanoylglycerol was mixed with bile salt solutions by sonication to form a micellar substrate before launching the assay. The nature of the bile salt and the bile salt to MGDG ratio were found to significantly affect the rate of MGDG hydrolysis by rHPLRP2 and rGPLRP2. The maximum galactolipase activity of both enzymes was recorded with sodium deoxycholate (NaDC) and at a NaDC to MGDG ratio of 1.33 and at basic pH values (8.0-9.0). The maximum rates of hydrolysis were obtained using a MGDG concentration of 10(-2) M and calcium chloride was found to be not necessary to obtain the maximum of activity. Under these conditions, the maximum turnovers of rGPLRP2 and rHPLRP2 on mixed NaDC/MGDG micelles were found to be 8000+/-500 and 2800+/-60 micromol/min/mg (U/mg), respectively. These activities are in the same order of magnitude as the activities on triglycerides of lipases and they are the highest specific activities ever reported for galactolipases. For the sake of comparison, the hydrolysis of mixed bile salt/MGDG micelles was also tested using other pancreatic lipolytic enzymes and only native and recombinant human carboxyl ester hydrolase were found to display significant but lower activities (240+/-17 and 432+/-62 U/mg, respectively) on MGDG.

Poly(N-vinyl-2-pyrrolidone)-stabilized palladium-platinum nanoparticles-catalyzed hydrolysis of ammonia borane for hydrogen generation

NASA Astrophysics Data System (ADS)

Rakap, Murat

2015-02-01

The catalytic use of highly efficient poly(N-vinyl-2-pyrrolidone)-stabilized palladium-platinum nanoparticles (4.2 ± 1.9 nm) in the hydrolysis of ammonia-borane is reported. The catalyst is prepared by co-reduction of two metal ions in ethanol/water mixture by an alcohol reduction method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. They are recyclable and highly active for hydrogen generation from the hydrolysis of ammonia-borane even at very low concentrations and temperature, providing a record numbers of average turnover frequency value (125 mol H2/mol cat.min-1) and maximum hydrogen generation rate (3468 L H2 min-1 (mol cat)-1). They also provide activation energy of 51.7 ± 2 kJ/mol for the hydrolysis of ammonia borane.

Effect of climate on the storage and turnover of carbon in soils

NASA Technical Reports Server (NTRS)

Trumbore, Susan; Chadwick, Oliver; Amundson, Ronald; Brasher, Benny

1994-01-01

Climate is, in many instances, the dominant variable controlling the storage of carbon in soils. It has proven difficult, however, to determine how soil properties influenced by climate, such as soil temperature and soil moisture, actually operate to determine the rates of accumulation and decomposition of soil organic matter. Our approach has been to apply a relatively new tool, the comparison of C-14 in soil organic matter from pre- and post-bomb soils, to quantify carbon turnover rates along climosequences. This report details the progress made toward this end by work under this contract.

Demands and Job Resources in the Child Care Workforce: Swiss Lead Teacher and Assistant Teacher Assessments

ERIC Educational Resources Information Center

Bloechliger, Olivia R.; Bauer, Georg F.

2016-01-01

Center-based child care has been struggling with poor health and high turnover rates of child care staff and their adverse impact on care quality for decades. Yet little is known about personal and structural antecedents of job resources and job demands that are valid predictors of health and turnover in the child care workforce. Research…

Estimating soil labile organic carbon and potential turnover rates using a sequential fumigation–incubation procedure.

Treesearch

X.M. Zoua; H.H. Ruanc; Y. Fua; X.D. Yanga; L.Q. Sha

2005-01-01

Labile carbon is the fraction of soil organic carbon with most rapid turnover times and its oxidation drives the flux of CO2 between soils and atmosphere. Available chemical and physical fractionation methods for estimating soil labile organic carbon are indirect and lack a clear biological definition. We have modified the well-established Jenkinson and Powlson’s...

Dissolved Phosphorus Pools and Alkaline Phosphatase Activity in the Euphotic Zone of the Western North Pacific Ocean

PubMed Central

Suzumura, Masahiro; Hashihama, Fuminori; Yamada, Namiha; Kinouchi, Shinko

2012-01-01

We measured pools of dissolved phosphorus (P), including dissolved inorganic P (DIP), dissolved organic P (DOP) and alkaline phosphatase (AP)-hydrolyzable labile DOP (L-DOP), and kinetic parameters of AP activity (APA) in the euphotic zone in the western North Pacific Ocean. Samples were collected from one coastal station in Sagami Bay, Japan, and three offshore stations between the North Pacific subtropical gyre (NPSG) and the Kuroshio region. Although DIP concentrations in the euphotic zone at all stations were equally low, around the nominal method detection limit of 20 nmol L-1, chlorophyll a (Chl a) concentrations were one order of magnitude greater at the coastal station. DOP was the dominant P pool, comprising 62–92% of total dissolved P at and above the Chl a maximum layer (CML). L-DOP represented 22–39% of the total DOP at the offshore stations, whereas it accounted for a much higher proportion (about 85%) in the coastal surface layers. Significant correlations between maximum potential AP hydrolysis rates and DIP concentrations or bacterial cell abundance in the offshore euphotic zone suggest that major APA in the oligotrophic surface ocean is from bacterial activity and regulated largely by DIP availability. Although the range of maximum potential APA was comparable among the environmental conditions, the in situ hydrolysis rate of L-DOP in the coastal station was 10 times those in the offshore stations. L-DOP turnover time at the CML ranged from 4.5 days at the coastal station to 84.4 days in the NPSG. The ratio of the APA half-saturation constant to the ambient L-DOP concentration decreased markedly from the NPSG to the coastal station. There were substantial differences in the rate and efficiency of DOP remineralization and its contribution as the potential P source between the low-phosphate/high-biomass coastal ecosystem and the low-phosphate/low biomass oligotrophic ocean. PMID:22457661

Mechanical and energetic properties of papillary muscle from ACTC E99K transgenic mouse models of hypertrophic cardiomyopathy

PubMed Central

Song, Weihua; Vikhorev, Petr G.; Kashyap, Mavin N.; Rowlands, Christina; Ferenczi, Michael A.; Woledge, Roger C.; MacLeod, Kenneth; Curtin, Nancy A.

2013-01-01

We compared the contractile performance of papillary muscle from a mouse model of hypertrophic cardiomyopathy [α-cardiac actin (ACTC) E99K mutation] with nontransgenic (non-TG) littermates. In isometric twitches, ACTC E99K papillary muscle produced three to four times greater force than non-TG muscle under the same conditions independent of stimulation frequency and temperature, whereas maximum isometric force in myofibrils from these muscles was not significantly different. ACTC E99K muscle relaxed slower than non-TG muscle in both papillary muscle (1.4×) and myofibrils (1.7×), whereas the rate of force development after stimulation was the same as non-TG muscle for both electrical stimulation in intact muscle and after a Ca2+ jump in myofibrils. The EC50 for Ca2+ activation of force in myofibrils was 0.39 ± 0.33 μmol/l in ACTC E99K myofibrils and 0.80 ± 0.11 μmol/l in non-TG myofibrils. There were no significant differences in the amplitude and time course of the Ca2+ transient in myocytes from ACTC E99K and non-TG mice. We conclude that hypercontractility is caused by higher myofibrillar Ca2+ sensitivity in ACTC E99K muscles. Measurement of the energy (work + heat) released in actively cycling heart muscle showed that for both genotypes, the amount of energy turnover increased with work done but with decreasing efficiency as energy turnover increased. Thus, ACTC E99K mouse heart muscle produced on average 3.3-fold more work than non-TG muscle, and the cost in terms of energy turnover was disproportionately higher than in non-TG muscles. Efficiency for ACTC E99K muscle was in the range of 11–16% and for non-TG muscle was 15–18%. PMID:23604709

Mechanical and energetic properties of papillary muscle from ACTC E99K transgenic mouse models of hypertrophic cardiomyopathy.

PubMed

Song, Weihua; Vikhorev, Petr G; Kashyap, Mavin N; Rowlands, Christina; Ferenczi, Michael A; Woledge, Roger C; MacLeod, Kenneth; Marston, Steven; Curtin, Nancy A

2013-06-01

We compared the contractile performance of papillary muscle from a mouse model of hypertrophic cardiomyopathy [α-cardiac actin (ACTC) E99K mutation] with nontransgenic (non-TG) littermates. In isometric twitches, ACTC E99K papillary muscle produced three to four times greater force than non-TG muscle under the same conditions independent of stimulation frequency and temperature, whereas maximum isometric force in myofibrils from these muscles was not significantly different. ACTC E99K muscle relaxed slower than non-TG muscle in both papillary muscle (1.4×) and myofibrils (1.7×), whereas the rate of force development after stimulation was the same as non-TG muscle for both electrical stimulation in intact muscle and after a Ca²⁺ jump in myofibrils. The EC₅₀ for Ca²⁺ activation of force in myofibrils was 0.39 ± 0.33 μmol/l in ACTC E99K myofibrils and 0.80 ± 0.11 μmol/l in non-TG myofibrils. There were no significant differences in the amplitude and time course of the Ca²⁺ transient in myocytes from ACTC E99K and non-TG mice. We conclude that hypercontractility is caused by higher myofibrillar Ca²⁺ sensitivity in ACTC E99K muscles. Measurement of the energy (work + heat) released in actively cycling heart muscle showed that for both genotypes, the amount of energy turnover increased with work done but with decreasing efficiency as energy turnover increased. Thus, ACTC E99K mouse heart muscle produced on average 3.3-fold more work than non-TG muscle, and the cost in terms of energy turnover was disproportionately higher than in non-TG muscles. Efficiency for ACTC E99K muscle was in the range of 11-16% and for non-TG muscle was 15-18%.

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.

Are nursing home survey deficiencies higher in facilities with greater staff turnover.

PubMed

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

2014-02-01

To examine CNA and licensed nurse (RN+LPN/LVN) turnover in relation to numbers of deficiencies in nursing homes. A secondary data analysis of information from the National Nursing Home Survey (NNHS) and contemporaneous data from the Online Survey, Certification and Reporting (OSCAR) database. Data were linked by facility as the unit of analysis to determine the relationship of CNA and licensed nurse turnover on nursing home deficiencies. The 2004 NNHS used a multistage sampling strategy to generate a final sample of 1174 nursing homes, which represent 16,100 NHs in the United States. This study focused on the 1151 NNHS facilities with complete deficiency data. Turnover was defined as the total CNAs/licensed nurse full-time equivalents (FTEs) who left during the preceding 3 months (full- and part-time) divided by the total FTE. NHs with high turnover were defined as those with rates above the 75th percentile (25.3% for CNA turnover and 17.9% for licensed nurse turnover) versus all other facilities. This study used selected OSCAR deficiencies from the Quality of Care, Quality of Life, and Resident Behavior categories, which are considered to be more closely related to nursing care. We defined NHs with high deficiencies as those with numbers of deficiencies above the 75th percentile versus all others. Using SUDAAN PROC RLOGIST, we included NNHS sampling design effects and examined associations of CNA/licensed nurse turnover with NH deficiencies, adjusting for staffing, skill mix, bed size, and ownership in binomial logistic regression models. High CNA turnover was associated with high numbers of Quality of Care (OR 1.53, 95% CI 1.10-2.13), Resident Behavior (OR 1.42, 95% CI 1.03-1.97) and total selected deficiencies (OR 1.54, 95% CI 1.12-2.12). Licensed nurse turnover was significantly related to Quality of Care deficiencies (OR 2.06, 95% CI 1.50-2.82) and total selected deficiencies (OR 1.71, 95% CI 1.25-2.33). When both CNA turnover and licensed nurse turnover were included in the same model, high licensed nurse turnover was significantly associated with Quality of Care and total deficiencies, whereas CNA turnover was not associated with that category of deficiencies. Turnover in nursing homes for both licensed nurses and CNAs is associated with quality problems as measured by deficiencies. Copyright © 2014 American Medical Directors Association, Inc. Published by Elsevier Inc. All rights reserved.

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.

Respiration and protein synthesis in nongrowing cultured pear fruit cells in response to ethylene and modified atmospheres. [Pyrus communis L. Passe Crassane

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

Brady, C.J.; Romani, R.J.

1988-07-01

The respiration of pear fruit (Pyrus communis L. Passe Crassane) cells was monitored after subculture into an auxin-free, mannitol-enriched medium in which the cells remained viable but did not grow. Respiration rates were affected by the presence or absence of sucrose in the medium even though the cells retained reserves of sucrose and starch. Provided the medium contained respirable carbohydrate, exposure to ethylene (1-10 microliters per liter) increased the respiration rate with some acceleration of cell death. In the range from 10 to 2% oxygen by volume, the respiration rate of the cells decreased with oxygen concentration resulting in somemore » prolongation of cell life. Thus, in their responses to ethylene and modified atmospheres, the cells reflected the behavior of harvested fruits. Having defined conditions under which respiration rate could be varied without apparent influence on the quiescent state of the cells, they sought a connection between maintenance respiration and protein turnover. Relative rates of protein synthesis were assessed by measuring ribosome distribution between monosomes and polysomes. In general, the higher the respiration rate the higher the proportion of polysomes supporting the thesis that protein turnover is a variable component of maintenance metabolism. Protein turnover in cells incubated in the presence or absence of sucrose was measured as retained {alpha}-amino-{sup 3}H following a pulse of {sup 3}H{sub 2}O. Turnover was shown to be a quantitatively important component of the maintenance budget and to be more rapidly in cells in media supplemented with sucrose through the chase period. The experiments illustrate that cultured cells may be used to explore aspects of the maintenance metabolism of resting or senescent cells that are not amenable to study in bulky fruit tissues.« less

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 cellular growth rate controls overall mRNA turnover, and modulates either transcription or degradation rates of particular gene regulons.

PubMed

García-Martínez, José; Delgado-Ramos, Lidia; Ayala, Guillermo; Pelechano, Vicent; Medina, Daniel A; Carrasco, Fany; González, Ramón; Andrés-León, Eduardo; Steinmetz, Lars; Warringer, Jonas; Chávez, Sebastián; Pérez-Ortín, José E

2016-05-05

We analyzed 80 different genomic experiments, and found a positive correlation between both RNA polymerase II transcription and mRNA degradation with growth rates in yeast. Thus, in spite of the marked variation in mRNA turnover, the total mRNA concentration remained approximately constant. Some genes, however, regulated their mRNA concentration by uncoupling mRNA stability from the transcription rate. Ribosome-related genes modulated their transcription rates to increase mRNA levels under fast growth. In contrast, mitochondria-related and stress-induced genes lowered mRNA levels by reducing mRNA stability or the transcription rate, respectively. We also detected these regulations within the heterogeneity of a wild-type cell population growing in optimal conditions. The transcriptomic analysis of sorted microcolonies confirmed that the growth rate dictates alternative expression programs by modulating transcription and mRNA decay.The regulation of overall mRNA turnover keeps a constant ratio between mRNA decay and the dilution of [mRNA] caused by cellular growth. This regulation minimizes the indiscriminate transmission of mRNAs from mother to daughter cells, and favors the response capacity of the latter to physiological signals and environmental changes. We also conclude that, by uncoupling mRNA synthesis from decay, cells control the mRNA abundance of those gene regulons that characterize fast and slow growth. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Consistent assignment of nurse aides: association with turnover and absenteeism.

PubMed

Castle, Nicholas G

2013-01-01

Consistent assignment refers to the same caregivers consistently caring for the same residents almost every time caregivers are on duty. This article examines the association of consistent assignment of nurse aides with turnover and absenteeism. Data came from a survey of nursing home administrators, the Online Survey Certification and Reporting data, and the Area Resource File. The measures were from 2007 and came from 3,941 nursing homes. Multivariate logistic regression models were used to examine turnover and absenteeism. An average of 68% of nursing homes reported using consistent assignment, with 28% of nursing homes using nurse aides consistent assignment at the often recommended level of 85% (or more). Nursing homes using recommended levels of consistent assignment had significantly lower rates of turnover and of absenteeism. In the multivariate analyses, consistent assignment was significantly associated with both lower turnover and lower absenteeism (p < .01). Consistent assignment is a practice recommended by many policy makers, government agencies, and industry advocates. The findings presented here provide some evidence that the use of this staffing practice can be beneficial.

Modelling the Impact of Different Tuberculosis Control Interventions on the Prevalence of Tuberculosis in an Overcrowded Prison.

PubMed

Naning, Herlianna; Al-Darraji, Haider Abdulrazzaq Abed; McDonald, Scott; Ismail, Noor Azina; Kamarulzaman, Adeeba

2018-04-01

The aim of this study was to simulate the effects of tuberculosis (TB) treatment strategies interventions in an overcrowded and poorly ventilated prison with both high (5 months) and low (3 years) turnover of inmates against improved environmental conditions. We used a deterministic transmission model to simulate the effects of treatment of latent TB infection and active TB, or the combination of both treatment strategies. Without any intervention, the TB prevalence is estimated to increase to 8.8% for a prison with low turnover of inmates but modestly stabilize at 5.8% for high-turnover prisons in a 10-year period. Reducing overcrowding from 6 to 4 inmates per housing cell and increasing the ventilation rate from 2 to 12 air changes per hour combined with any treatment strategy would further reduce the TB prevalence to as low as 0.98% for a prison with low inmate turnover.

The relationship between perceptions of organizational functioning and voluntary counselor turnover: A four-wave longitudinal study

PubMed Central

Eby, Lillian T.; Rothrauff-Laschober, Tanja C.

2011-01-01

Using data from a nationwide study, we annually track a cohort of 598 substance use disorder counselors over a 4-wave period to (1) document the cumulative rates of voluntary turnover and (2) examine how counselor perceptions of the organizational environment (procedural justice, distributive justice, perceived organizational support, job satisfaction) and clinical supervisor leadership effectiveness (relationship quality, in-role performance, extra-role performance) predict voluntary turnover over time. Survey data were collected from counselors in year 1 and actual turnover data were collected from organizational records in year 2, 3, and 4. Findings reveal that 25% of the original counselors turned over by year 2, 39% by year 3, and 47% by year 4. Counselors with more favorable perceptions of the organizational environment are between 13.8% – 22.8% less likely to turn over than those with less favorable perceptions. None of the leadership effectiveness variables are significant. PMID:22116013

Evaluating the effectiveness of a logger safety training program.

PubMed

Bell, Jennifer L; Grushecky, Shawn T

2006-01-01

Logger safety training programs are rarely, if ever, evaluated as to their effectiveness in reducing injuries. Workers' compensation claim rates were used to evaluate the effectiveness of a logger safety training program, the West Virginia Loggers' Safety Initiative (LSI). There was no claim rate decline detected in the majority (67%) of companies that participated in all 4 years of the LSI. Furthermore, their rate did not differ from the rest of the WV logging industry that did not participate in the LSI. Worker turnover was significantly related to claim rates; companies with higher turnover of employees had higher claim rates. Companies using feller bunchers to harvest trees at least part of the time had a significantly lower claim rate than companies not using them. Companies that had more inspections per year had lower claim rates. High injury rates persist even in companies that receive safety training; high employee turnover may affect the efficacy of training programs. The logging industry should be encouraged to facilitate the mechanization of logging tasks, to address barriers to employee retention, and to increase the number of in-the-field performance monitoring inspections. Impact on industry There are many states whose logger safety programs include only about 4-8 hours of safe work practices training. These states may look to West Virginia's expanded training program (the LSI) as a model for their own programs. However, the LSI training may not be reaching loggers due to the delay in administering training to new employees and high levels of employee turnover. Regardless of training status, loggers' claim rates decline significantly the longer they work for a company. It may be that high injury rates in the state of West Virginia would be best addressed by finding ways to encourage and facilitate companies to become more mechanized in their harvesting practices, and to increase employee tenure. Increasing the number of yearly performance inspections may also be a venue to reduce claim rates. Future research could investigate in better detail the working conditions of West Virginia loggers and identify barriers to job tenure, particularly for workers whose primary job task is chainsaw operation. A larger-scale study of the effect of performance monitoring inspections on claim rates is also warranted.

Synthetic Constraint of Ecosystem C Models Using Radiocarbon and Net Primary Production (NPP) in New Zealand Grazing Land

NASA Astrophysics Data System (ADS)

Baisden, W. T.

2011-12-01

Time-series radiocarbon measurements have substantial ability to constrain the size and residence time of the soil C pools commonly represented in ecosystem models. Radiocarbon remains unique in the ability to constrain the large stabilized C pool with decadal residence times. Radiocarbon also contributes usefully to constraining the size and turnover rate of the passive pool, but typically struggles to constrain pools with residence times less than a few years. Overall, the number of pools and associated turnover rates that can be constrained depends upon the number of time-series samples available, the appropriateness of chemical or physical fractions to isolate unequivocal pools, and the utility of additional C flux data to provide additional constraints. In New Zealand pasture soils, we demonstrate the ability to constrain decadal turnover times with in a few years for the stabilized pool and reasonably constrain the passive fraction. Good constraint is obtained with two time-series samples spaced 10 or more years apart after 1970. Three or more time-series samples further improve the level of constraint. Work within this context shows that a two-pool model does explain soil radiocarbon data for the most detailed profiles available (11 time-series samples), and identifies clear and consistent differences in rates of C turnover and passive fraction in Andisols vs Non-Andisols. Furthermore, samples from multiple horizons can commonly be combined, yielding consistent residence times and passive fraction estimates that are stable with, or increase with, depth in different sites. Radiocarbon generally fails to quantify rapid C turnover, however. Given that the strength of radiocarbon is estimating the size and turnover of the stabilized (decadal) and passive (millennial) pools, the magnitude of fast cycling pool(s) can be estimated by subtracting the radiocarbon-based estimates of turnover within stabilized and passive pools from total estimates of NPP. In grazing land, these estimates can be derived primarily from measured aboveground NPP and calculated belowground NPP. Results suggest that only 19-36% of heterotrophic soil respiration is derived from the soil C with rapid turnover times. A final logical step in synthesis is the analysis of temporal variation in NPP, primarily due to climate, as driver of changes in plant inputs and resulting in dynamic changes in rapid and decadal soil C pools. In sites with good time series samples from 1959-1975, we examine the apparent impacts of measured or modelled (Biome-BGC) NPP on soil Δ14C. Ultimately, these approaches have the ability to empirically constrain, and provide limited verification, of the soil C cycle as commonly depicted ecosystem biogeochemistry models.

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

An Economic Analysis of a Safe Resident Handling Program in Nursing Homes

PubMed Central

Lahiri, Supriya; Latif, Saira; Punnett, Laura

2018-01-01

Background Occupational injuries, especially back problems related to resident handling, are common in nursing home employees and their prevention may require substantial up-front investment. This study evaluated the economics of a safe resident handling program (SRHP), in a large chain of skilled nursing facilities, from the corporation's perspective. Methods The company provided data on program costs, compensation claims, and turnover rates (2003-2009). Workers' compensation and turnover costs before and after the intervention were compared against investment costs using the “net-cost model”. Results Among 110 centers, the overall benefit-to-cost ratio was 1.7–3.09 and the payback period was 1.98–1.06 year (using alternative turnover cost estimates). The average annualized net savings per bed for the 110 centers (using company based turnover cost estimates) was $143, with a 95% confidence interval of $22–$264. This was very similar to the average annualized net savings per full time equivalent (FTE) staff member, which was $165 (95% confidence interval $22–$308). However, at 49 centers costs exceeded benefits. Conclusions Decreased costs of worker injury compensation claims and turnover appear at least partially attributable to the SRHP. Future research should examine center-specific factors that enhance program success, and improve measures of turnover costs and healthcare productivity. PMID:23203729

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

An economic analysis of a safe resident handling program in nursing homes.

PubMed

Lahiri, Supriya; Latif, Saira; Punnett, Laura

2013-04-01

Occupational injuries, especially back problems related to resident handling, are common in nursing home employees and their prevention may require substantial up-front investment. This study evaluated the economics of a safe resident handling program (SRHP), in a large chain of skilled nursing facilities, from the corporation's perspective. The company provided data on program costs, compensation claims, and turnover rates (2003-2009). Workers' compensation and turnover costs before and after the intervention were compared against investment costs using the "net-cost model." Among 110 centers, the overall benefit-to-cost ratio was 1.7-3.09 and the payback period was 1.98-1.06 year (using alternative turnover cost estimates). The average annualized net savings per bed for the 110 centers (using company based turnover cost estimates) was $143, with a 95% confidence interval of $22-$264. This was very similar to the average annualized net savings per full time equivalent (FTE) staff member, which was $165 (95% confidence interval $22-$308). However, at 49 centers costs exceeded benefits. Decreased costs of worker injury compensation claims and turnover appear at least partially attributable to the SRHP. Future research should examine center-specific factors that enhance program success, and improve measures of turnover costs and healthcare productivity. Copyright © 2012 Wiley Periodicals, Inc.

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.

Effect of a protein-free diet on muscle protein turnover and nitrogen conservation in euthyroid and hyperthyroid rats.

PubMed Central

Carter, W J; van der Weijden Benjamin, W S; Faas, F H

1984-01-01

Although protein turnover in skeletal muscle is increased in hyperthyroidism and decreased in hypothyroidism, a deficient protein intake tends to increase serum T3 (tri-iodothyronine) while decreasing muscle protein turnover. To determine whether this diet-induced decrease in protein turnover can occur independent of thyroid status, we have examined muscle protein turnover and nitrogen conservation in hyperthyroid rats fed on a protein-free diet. After inducing hyperthyroidism by giving 20 micrograms of T3/100g body wt. daily for 7 days, groups of euthyroid and hyperthyroid animals were divided into subgroups fed on basal and protein-free diets. Muscle protein turnover was measured by N tau-methylhistidine excretion and [14C]tyrosine infusion. Urinary nitrogen output of euthyroid and hyperthyroid animals fed on the protein-free diet was also measured. Although hyperthyroidism increased the baseline rates of muscle protein synthesis and degradation, it did not prevent a decrease in these values in response to protein depletion. Furthermore, hyperthyroid rats showed greatly decreased nitrogen excretion in response to the protein-free diet, although not to values for euthyroid rats. These findings suggest that protein depletion made the experimental animals less responsive to the protein-catabolic effects of T3. PMID:6696742

Magnetic pair creation transparency in gamma-ray pulsars

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

Story, Sarah A.; Baring, Matthew G., E-mail: ss16@rice.edu, E-mail: baring@rice.edu

2014-07-20

Magnetic pair creation, γ → e {sup +} e {sup –}, has been at the core of radio pulsar paradigms and central to polar cap models of gamma-ray pulsars for over three decades. The Fermi gamma-ray pulsar population now exceeds 140 sources and has defined an important part of Fermi's science legacy, providing rich information for the interpretation of young energetic pulsars and old millisecond pulsars. Among the population characteristics well established is the common occurrence of exponential turnovers in their spectra in the 1-10 GeV range. These turnovers are too gradual to arise from magnetic pair creation in themore » strong magnetic fields of pulsar inner magnetospheres. By demanding insignificant photon attenuation precipitated by such single-photon pair creation, the energies of these turnovers for Fermi pulsars can be used to compute lower bounds for the typical altitude of GeV band emission. This paper explores such pair transparency constraints below the turnover energy and updates earlier altitude bound determinations that have been deployed in various Fermi pulsar papers. For low altitude emission locales, general relativistic influences are found to be important, increasing cumulative opacity, shortening the photon attenuation lengths, and also reducing the maximum energy that permits escape of photons from a neutron star magnetosphere. Rotational aberration influences are also explored, and are found to be small at low altitudes, except near the magnetic pole. The analysis presented in this paper clearly demonstrates that including near-threshold physics in the pair creation rate is essential to deriving accurate attenuation lengths and escape energies. The altitude bounds are typically in the range of 2-7 stellar radii for the young Fermi pulsar population, and provide key information on the emission altitude in radio quiet pulsars that do not possess double-peaked pulse profiles. The bound for the Crab pulsar is at a much higher altitude, with the putative detection by MAGIC out to 350-400 GeV implying a lower bound of 310 km to the emission region, i.e., approximately 20% of the light cylinder radius. These results are also extended to the super-critical field domain, where it is found that emission in neurton stars originating below around 10 stellar radii will not appear in the Fermi-LAT band.« less

Magnetic Pair Creation Transparency in Gamma-Ray Pulsars

NASA Astrophysics Data System (ADS)

Story, Sarah A.; Baring, Matthew G.

2014-07-01

Magnetic pair creation, γ → e + e -, has been at the core of radio pulsar paradigms and central to polar cap models of gamma-ray pulsars for over three decades. The Fermi gamma-ray pulsar population now exceeds 140 sources and has defined an important part of Fermi's science legacy, providing rich information for the interpretation of young energetic pulsars and old millisecond pulsars. Among the population characteristics well established is the common occurrence of exponential turnovers in their spectra in the 1-10 GeV range. These turnovers are too gradual to arise from magnetic pair creation in the strong magnetic fields of pulsar inner magnetospheres. By demanding insignificant photon attenuation precipitated by such single-photon pair creation, the energies of these turnovers for Fermi pulsars can be used to compute lower bounds for the typical altitude of GeV band emission. This paper explores such pair transparency constraints below the turnover energy and updates earlier altitude bound determinations that have been deployed in various Fermi pulsar papers. For low altitude emission locales, general relativistic influences are found to be important, increasing cumulative opacity, shortening the photon attenuation lengths, and also reducing the maximum energy that permits escape of photons from a neutron star magnetosphere. Rotational aberration influences are also explored, and are found to be small at low altitudes, except near the magnetic pole. The analysis presented in this paper clearly demonstrates that including near-threshold physics in the pair creation rate is essential to deriving accurate attenuation lengths and escape energies. The altitude bounds are typically in the range of 2-7 stellar radii for the young Fermi pulsar population, and provide key information on the emission altitude in radio quiet pulsars that do not possess double-peaked pulse profiles. The bound for the Crab pulsar is at a much higher altitude, with the putative detection by MAGIC out to 350-400 GeV implying a lower bound of 310 km to the emission region, i.e., approximately 20% of the light cylinder radius. These results are also extended to the super-critical field domain, where it is found that emission in magnetars originating below around 10 stellar radii will not appear in the Fermi-LAT band.

Prevalence-Based Targets Underestimate Home Dialysis Program Activity and Requirements for Growth.

PubMed

Bevilacqua, Micheli U; Er, Lee; Copland, Michael A; Singh, R Suneet; Jamal, Abeed; Dunne, Órla Marie; Brumby, Catherine; Levin, Adeera

2018-01-01

Many renal programs have targets to increase home dialysis prevalence. Data from a large Canadian home dialysis program were analyzed to determine if home dialysis prevalence accurately reflects program activity and whether prevalence-based assessments adequately reflect the work required for program growth. Data from home dialysis programs in British Columbia, Canada, were analyzed from 2005 to 2015. Prevalence data were compared to dialysis activity data including intakes and exits to describe program turnover. Using current attrition rates, recruitment rates needed to increase home dialysis prevalence proportions were identified. We analyzed 7,746 patient-years of peritoneal dialysis (PD) and 1,362 patient-years of home hemodialysis (HHD). The proportion of patients on home dialysis increased by 3.34% over the ten years examined, while the number of prevalent home dialysis patients increased 2.65% per year and the number of patients receiving home dialysis at any time in the year increased 4.04% per year. For every 1 patient net home dialysis growth, 13.6 new patients were recruited. Patient turnover included higher rates of transplantation in home dialysis than facility-based HD. Overall, the proportion dialyzing at home increased from 29.3 to 32.6%. There is high patient turnover in home dialysis such that program prevalence is an incomplete marker of total program activity. This turnover includes high rates of transplantation, which is a desirable interaction that affects home dialysis prevalence. The shortcomings of this commonly used metric are important for renal programs to consider, and better understanding of the activities that support home dialysis and the complex trajectories that home dialysis patients follow is needed. Copyright © 2018 International Society for Peritoneal Dialysis.

Health Workforce Acquisition, Retention and Turnover in Southwest Ethiopian Health Institutions.

PubMed

Gesesew, Hailay Abrha; Tebeje, Bosena; Alemseged, Fessahaye; Beyene, Waju

2016-07-01

Skill mix of health professionals, staff acquisition and turnover rate are among the major challenges for the delivery of quality health care. This study assessed the health workforce acquisition, retention, turnover rate and their intention to leave. A cross-sectional survey with quantitative and qualitative data collection methods was conducted in Jimma Zone health institutions. Five years records (September 2009-August 2014) were reviewed to determine the turnover rate. A total of 367 health professionals were included for the quantitative study. For the qualitaive study, all available and relevant health managers and administrative records in the selected health institutions were included. Descriptive and inferential analyses were done for the quantitative study. Thematic analysis was used for the qualitative component. A total of 367 health workers were incorporated for the quantitative study making a response rate of 87%. The overall health workers' satisfaction was neutral (mean 3.3). In five years period, 45.9% staffs had left for a cause; 59.4% health professionals intended to leave. Being male (AOR =1.6, 95%CI: 1.001-2.5), not knowing their overall satisfaction (AOR=0.5, 95%CI: 0.2-0.8), below mean score of institutional satisfaction (AOR =1.7, 95%CI: 1.06-2.7) and below mean score of organizational satisfaction (AOR=1.8, 95%CI: 1.08-2.8) were independent predictors for intention to leave. The overall health workers' satisfaction was marginally neutral. A considerable number of staffs had left, and more than half of the current staffs had an intention to leave. Thus, it is recommended that the responsible authorities should design strategies to improve the situation.

Estimating soil turnover rate from tree uprooting during hurricanes in Puerto Rico

Treesearch

Melanie T. Lenart; D.A. Falk; F.N. Scatena; W.R. Osterkamp

2010-01-01

Soil turnover by tree uprooting in primary and secondary forests on the island of Puerto Rico was measured in 42 study plots in the months immediately after the passage of a Category 3 hurricane. Trunk basal area explained 61% of the variability of mound volume and 53% of the variability of mound area. The proportion of uprooted trees, the number of uprooted trees, or...

Mechanism of Copper(I)/TEMPO-Catalyzed Aerobic Alcohol Oxidation

PubMed Central

Hoover, Jessica M.; Ryland, Bradford L.; Stahl, Shannon S.

2013-01-01

Homogeneous Cu/TEMPO catalyst systems (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) have emerged as some of the most versatile and practical catalysts for aerobic alcohol oxidation. Recently, we disclosed a (bpy)CuI/TEMPO/NMI catalyst system (NMI = N-methylimidazole) that exhibits fast rates and high selectivities, even with unactivated aliphatic alcohols. Here, we present a mechanistic investigation of this catalyst system, in which we compare the reactivity of benzylic and aliphatic alcohols. This work includes analysis of catalytic rates by gas-uptake and in situ IR kinetic methods and characterization of the catalyst speciation during the reaction by EPR and UV–visible spectroscopic methods. The data support a two-stage catalytic mechanism consisting of (1) “catalyst oxidation” in which CuI and TEMPO–H are oxidized by O2 via a binuclear Cu2O2 intermediate and (2) “substrate oxidation” mediated by CuII and the nitroxyl radical of TEMPO via a CuII-alkoxide intermediate. Catalytic rate laws, kinetic isotope effects, and spectroscopic data show that reactions of benzylic and aliphatic alcohols have different turnover-limiting steps. Catalyst oxidation by O2 is turnover limiting with benzylic alcohols, while numerous steps contribute to the turnover rate in the oxidation of aliphatic alcohols. PMID:23317450

The impact of generic substitution on the turnover and gross margin of pharmaceutical companies a survey 1 year and 5 years after the introduction of generic substitution in Finland.

PubMed

Timonen, Johanna; Karttunen, Pekka; Bengtström, Marina; Ahonen, Riitta

2009-10-01

To explore and compare the impact of generic substitution (GS) on the turnover and gross margin per cent of pharmaceutical companies representing mainly original or generic products in Finland. A mail survey to pharmaceutical companies with an office in Finland and substitutable medicines in the Finnish pharmaceutical market 1 year (2004) and nearly 5 years (2008) after GS. The questionnaire were answered by 16 original and 7 generic product companies in 2004 (response rate 56%, n=41) and by 16 original and 6 generic product companies in 2008 (response rate 56%, n=39). Turnover had decreased in the original product companies and increased in the generic product companies. The gross margin per cent had decreased in the original and generic product companies, and the companies had also compensated for it in many ways. The study suggests that GS has promoted the sales of generic product companies in Finland. However, price competition caused by GS has generally decreased the proportion of profit from turnover in the original and generic product companies. The companies have also compensated for their decreased gross margin, which suggests that the profit in euros has not been sufficient to cover fixed costs in the companies.

Tenure of academic chairs in obstetrics and gynecology: a 25-year perspective.

PubMed

Rayburn, William F; Schrader, Ronald M; Cain, Joanna M; Artal, Raul; Anderson, Garland D; Merkatz, Irwin R

2006-11-01

To assist in predicting future leadership needs, this longitudinal study examines turnover and net retention rates among chairs at university obstetrics and gynecology departments between 1981 and 2005. A database of appointment dates and tenure of chairs at each of 125 Association of American Medical Colleges-approved United States medical schools was collated using membership listings from the Association of Professors of Gynecology and Obstetrics and from the Council of University Chairs in Obstetrics and Gynecology. Complete data from 118 departments were confirmed by selective correspondence at individual departments and further review by the investigators. A total of 260 individuals (232 men, 28 women) became new chairs between 1981 and 2005. The annual turnover rate increased gradually from 6.0% to 12.7%. Five-year net retention rates remained steady between 1982 and 1997 but dropped after 1997 (85.6% compared with 63.2%; P=.03). A chair's tenure ranged widely (1 to 23 years; median 8 years), regardless of gender or school type, size, or location. Approximately one half of interim chairs became permanent chairs, usually at their own institution. The number of new women chairs increased from none in 1981 to 17 (15.2% of total chairs) in 2005. Academic chair positions in obstetrics and gynecology experienced a doubling in annual turnover rates, while retention rates declined. The proportion of chairs occupied by women increased progressively. II-2.

Transcriptional regulation of ceruloplasmin gene expression during inflammation

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

Gitlin, J.D.

1988-05-05

Mixed sequence oligonucleotides were used to isolate a series of acute-phase human liver cDNA clones corresponding to the serum ..cap alpha../sub 2/-globulin ceruloplasmin. These clones were characterized, sequenced, and used to analyze changes in hepatic ceruloplasmin mRNA content during inflammation. In all species examined, hepatic ceruloplasmin mRNA content increased approximately 6-10-fold over control values within 24 h following the induction of inflammation. The mechanisms leading to this increase in hepatic ceruloplasmin mRNA content were studied following turpentine-induced inflammation in Syrian hamsters. Nuclear run-on assays demonstrated an increase in the relative rate of transcription of the ceruloplasmin gene within 3 hmore » following induction, reaching maximum values by 18 h. Hepatic ceruloplasmin mRNA content increased 2-fold within 12 h following induction, reached maximum values by 24 h, and returned to control within 72 h. In contrast, serum ceruloplasmin concentration did not increase until 36 h, reached maximal levels by 120 h, and remained elevated for the course of the study. These data indicate that inflammation leads to a rapid increase in hepatic ceruloplasmin mRNA content. This increase is largely the result of increased ceruloplasmin gene transcription, but comparison of the relative rate of transcription and mRNA accumulation suggests that changes in ceruloplasmin mRNA turnover are also involved. In addition, translational and/or post-translational mechanisms must account for the observed changes in serum ceruloplasmin concentration seen during inflammation.« less

Seasonal variation in natural abundance of 2H and 18O in urine samples from rural Nigeria

PubMed Central

Dugas, Lara R.; Brieger, William; Tayo, Bamidele O.; Alabi, Tunrayo; Schoeller, Dale A.; Luke, Amy

2015-01-01

The doubly labeled water (DLW) method is used to measure free-living energy expenditure in humans. Inherent to this technique is the assumption that natural abundances of stable isotopes 2H and 18O in body water remain constant over the course of the measurement period and after elimination of the loading dose of DLW will return to the same predose level. To determine variability in the natural abundances of 2H and 18O in humans living in a region with seasonal shifts in rain patterns and sources of drinking water, over the course of 12 mo we collected weekly urine samples from four individuals living in southwest Nigeria as well as samples of their drinking water. From ongoing regional studies of hypertension, obesity, and energy expenditure, we estimated average water turnover rate, urine volumes, and sodium and potassium excretion. Results suggest that 2H and 18O in urine, mean concentrations of urinary sodium and potassium, urine volume, and total body turnover differed significantly from dry to rainy season. Additionally, seasonal weather variables (mean monthly maximum temperatures, total monthly rainfall, and minimum relative humidity) were all significantly associated with natural abundances in urine. No seasonal difference was observed in drinking water samples. Findings suggest that natural abundances in urine may not remain constant as assumed, and studies incorporating DLW measurements across the transition of seasons should interpret results with caution unless appropriate doses of the tracers are used. PMID:25977450

Involvement of Abscisic Acid in PSII Photodamage and D1 Protein Turnover for Light-Induced Premature Senescence of Rice Flag Leaves

PubMed Central

Wang, Fubiao; Liu, Jianchao; Chen, Minxue; Zhou, Lujian; Li, Zhaowei; Zhao, Qian; Pan, Gang; Zaidi, Syed-Hassan-Raza; Cheng, Fangmin

2016-01-01

D1 protein in the PSII reaction center is the major target of photodamage, and it exhibits the highest turnover rate among all the thylakoid proteins. In this paper, rice psf (premature senescence of flag leaves) mutant and its wild type were used to investigate the genotype-dependent alteration in PSII photo-damage and D1 protein turnover during leaf senescence and its relation to ABA accumulation in senescent leaves. The symptom and extent of leaf senescence of the psf mutant appeared to be sunlight-dependent under natural field condition. The psf also displayed significantly higher levels of ABA accumulation in senescent leaves than the wild type. However, the premature senescence lesion of psf leaves could be alleviated by shaded treatment, concomitantly with the strikingly suppressed ABA level in the shaded areas of flag leaves. The change in ABA concentration contributed to the regulation of shade-delayed leaf senescence. The participation of ABA in the timing of senescence initiation and in the subsequent rate of leaf senescence was closely associated with PSII photodamage and D1 protein turnover during leaf senescence, in which the transcriptional expression of several key genes (psbA, psbB, psbC and OsFtsH2) involved in D1 protein biosynthesis and PSII repair cycle was seriously suppressed by the significantly increased ABA level. This response resulted in the low rate of D1 protein synthesis and impaired repair recovery in the presence of ABA. The psf showed evidently decreased D1 protein amount in the senescent leaves. Both the inhibition of de novo synthesized D1 protein and the slow rate of proteolytic removal for the photodamaged D1 protein was among the most crucial steps for the linkage between light-dependent leaf senescence and the varying ABA concentration in psf mutant leaves. OsFtsH2 transcriptional expression possibly played an important role in the regulation of D1 protein turnover and PSII repair cycle in relation to ABA mediated leaf senescence. PMID:27532299

FOXO/DAF-16 Activation Slows Down Turnover of the Majority of Proteins in C. elegans

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

Dhondt, Ineke; Petyuk, Vladislav A.; Cai, Huaihan

2016-09-01

Cellular protein quality can be maintained by proteolytic elimination of damaged proteins and replacing them with newly synthesized copies, a process called protein turnover (Ward, 2000). Protein turnover rates have been estimated using SILAC (stable isotope labeling by amino acids in cell culture) in prokaryotes and eukaryotes. The last decade has witnessed a growing interest in the analysis of whole-organism proteome dynamics in metazoans using the same approach (Claydon and Beynon, 2012). In recent work, SILAC was applied to monitor protein synthesis throughout life in adult Caenorhabditis elegans (Vukoti et al., 2015) and to investigate food intake (Gomez-Amaro et al.,more » 2015« less

Replicator dynamics with turnover of players

NASA Astrophysics Data System (ADS)

Juul, Jeppe; Kianercy, Ardeshir; Bernhardsson, Sebastian; Pigolotti, Simone

2013-08-01

We study adaptive dynamics in games where players abandon the population at a given rate and are replaced by naive players characterized by a prior distribution over the admitted strategies. We demonstrate how such a process leads macroscopically to a variant of the replicator equation, with an additional term accounting for player turnover. We study how Nash equilibria and the dynamics of the system are modified by this additional term for prototypical examples such as the rock-paper-scissors game and different classes of two-action games played between two distinct populations. We conclude by showing how player turnover can account for nontrivial departures from Nash equilibria observed in data from lowest unique bid auctions.

Occupational Stress and Turnover Intention: Implications for Nursing Management

PubMed Central

Mosadeghrad, Ali Mohammad

2013-01-01

Background: The main purpose of this study was to explore the status of occupational stress among hospital nurses in Isfahan, Iran. It also aimed to examine the relationship between nurses’ occupational stress and their intention to leave the hospital. Methods: The study employed a cross-sectional research design. A validated questionnaire was used to collect data from 296 nurses. Respondents were asked to rate the intensity of 30 common occupational stressors using a five-point scale. Results: A third of hospital nurses rated their occupational stress high. The major sources of stress were inadequate pay, inequality at work, too much work, staff shortage, lack of promotion, job insecurity and lack of management support. More than 35% of nurses stated that they are considering leaving the hospital, if they could find another job opportunity. Occupational stress was positively associated with nurses’ turnover intentions. Conclusion: Hospital managers should develop and apply appropriate policies and strategies to reduce occupational stress and consequently nurses’ turnover intention. PMID:24596858

Erythropoiesis and myocardial energy requirements contribute to the hypermetabolism of childhood sickle cell anemia.

PubMed

Hibbert, Jacqueline M; Creary, Melissa S; Gee, Beatrice E; Buchanan, Iris D; Quarshie, Alexander; Hsu, Lewis L

2006-11-01

We hypothesized that an elevated hemoglobin synthesis rate (SynHb) and myocardial oxygen consumption (MVO2) contribute to the excess protein and energy metabolism reported in children with sickle cell anemia. Twelve children (6-12 years old) with asymptomatic sickle cell and 9 healthy children matched for age and sex were studied. Measurements were whole-body protein turnover by [1-C]leucine, SynHb by [N]glycine, resting energy expenditure by indirect calorimetry and the systolic blood pressure-heart rate product used as an index of MVO2. Protein energy cost was calculated from protein turnover. Statistical analysis included Spearman correlations and partial correlation analyses. Although body mass index was significantly lower for sickle cell versus controls (P < 0.02), children with asymptomatic sickle cell had 52% higher protein turnover (P < 0.0005). Proportional reticulocyte count, SynHb, MVO2 and resting energy expenditure were also significantly higher in children with sickle cell (P < 0.01). Protein turnover correlated significantly with both SynHb (r = 0.63, P < 0.01) and reticulocyte percentage (r = 0.83, P < 0.0001). Partial correlation of these 3 variables showed reticulocyte percentage as the only variable to be significantly associated with protein turnover, even after adjusting for sickle cell anemia (P = 0.03). Partial correlation of log resting energy expenditure on MVO2 was significant, controlling for protein energy cost, sex and age (P = 0.03). These results indicate that metabolic demands of increased erythropoiesis and cardiac energy consumption account for much of the excess protein and energy metabolism in children with sickle cell anemia.

Matrix metabolism rate differs in functionally distinct tendons.

PubMed

Birch, Helen L; Worboys, Sarah; Eissa, Sabry; Jackson, Brendan; Strassburg, Sandra; Clegg, Peter D

2008-04-01

Tendon matrix integrity is vital to ensure adequate mechanical properties for efficient function. Although historically tendon was considered to be relatively inert, recent studies have shown that tendon matrix turnover is active. During normal physiological activities some tendons are subjected to stress and strains much closer to their failure properties than others. Tendons with low safety margins are those which function as energy stores such as the equine superficial digital flexor tendon (SDFT) and human Achilles tendon (AT). We postulate therefore that energy storing tendons suffer a higher degree of micro-damage and thus have a higher rate of matrix turnover than positional tendons. The hypothesis was tested using tissue from the equine SDFT and common digital extensor tendon (CDET). Matrix turnover was assessed indirectly by a combination of measurements for matrix age, markers of degradation, potential for degradation and protein expression. Results show that despite higher cellularity, the SDFT has lower relative levels of mRNA for collagen types I and III. Non-collagenous proteins, although expressed at different levels per cell, do not appear to differ between tendon types. Relative levels of mRNA for MMP1, MMP13 and both pro-MMP3 and MMP13 protein activity were significantly higher in the CDET. Correspondingly levels of cross-linked carboxyterminal telopeptide of type I collagen (ICTP) were higher in the CDET and tissue fluorescence lower suggesting more rapid turnover of the collagenous component. Reduced or inhibited collagen turnover in the SDFT may account for the high level of degeneration and subsequent injury compared to the CDET.

Importance of vegetation dynamics for future terrestrial carbon cycling

NASA Astrophysics Data System (ADS)

Ahlström, Anders; Xia, Jianyang; Arneth, Almut; Luo, Yiqi; Smith, Benjamin

2015-05-01

Terrestrial ecosystems currently sequester about one third of anthropogenic CO2 emissions each year, an important ecosystem service that dampens climate change. The future fate of this net uptake of CO2 by land based ecosystems is highly uncertain. Most ecosystem models used to predict the future terrestrial carbon cycle share a common architecture, whereby carbon that enters the system as net primary production (NPP) is distributed to plant compartments, transferred to litter and soil through vegetation turnover and then re-emitted to the atmosphere in conjunction with soil decomposition. However, while all models represent the processes of NPP and soil decomposition, they vary greatly in their representations of vegetation turnover and the associated processes governing mortality, disturbance and biome shifts. Here we used a detailed second generation dynamic global vegetation model with advanced representation of vegetation growth and mortality, and the associated turnover. We apply an emulator that describes the carbon flows and pools exactly as in simulations with the full model. The emulator simulates ecosystem dynamics in response to 13 different climate or Earth system model simulations from the Coupled Model Intercomparison Project Phase 5 ensemble under RCP8.5 radiative forcing. By exchanging carbon cycle processes between these 13 simulations we quantified the relative roles of three main driving processes of the carbon cycle; (I) NPP, (II) vegetation dynamics and turnover and (III) soil decomposition, in terms of their contribution to future carbon (C) uptake uncertainties among the ensemble of climate change scenarios. We found that NPP, vegetation turnover (including structural shifts, wild fires and mortality) and soil decomposition rates explained 49%, 17% and 33%, respectively, of uncertainties in modelled global C-uptake. Uncertainty due to vegetation turnover was further partitioned into stand-clearing disturbances (16%), wild fires (0%), stand dynamics (7%), reproduction (10%) and biome shifts (67%) globally. We conclude that while NPP and soil decomposition rates jointly account for 83% of future climate induced C-uptake uncertainties, vegetation turnover and structure, dominated by biome shifts, represent a significant fraction globally and regionally (tropical forests: 40%), strongly motivating their representation and analysis in future C-cycle studies.

Southern Ocean phytoplankton turnover in response to stepwise Antarctic cooling over the past 15 million years

PubMed Central

Crampton, James S.; Cody, Rosie D.; Levy, Richard; Harwood, David; McKay, Robert; Naish, Tim R.

2016-01-01

It is not clear how Southern Ocean phytoplankton communities, which form the base of the marine food web and are a crucial element of the carbon cycle, respond to major environmental disturbance. Here, we use a new model ensemble reconstruction of diatom speciation and extinction rates to examine phytoplankton response to climate change in the southern high latitudes over the past 15 My. We identify five major episodes of species turnover (origination rate plus extinction rate) that were coincident with times of cooling in southern high-latitude climate, Antarctic ice sheet growth across the continental shelves, and associated seasonal sea-ice expansion across the Southern Ocean. We infer that past plankton turnover occurred when a warmer-than-present climate was terminated by a major period of glaciation that resulted in loss of open-ocean habitat south of the polar front, driving non-ice adapted diatoms to regional or global extinction. These findings suggest, therefore, that Southern Ocean phytoplankton communities tolerate “baseline” variability on glacial–interglacial timescales but are sensitive to large-scale changes in mean climate state driven by a combination of long-period variations in orbital forcing and atmospheric carbon dioxide perturbations. PMID:27274061

Southern Ocean phytoplankton turnover in response to stepwise Antarctic cooling over the past 15 million years

NASA Astrophysics Data System (ADS)

Crampton, James S.; Cody, Rosie D.; Levy, Richard; Harwood, David; McKay, Robert; Naish, Tim R.

2016-06-01

It is not clear how Southern Ocean phytoplankton communities, which form the base of the marine food web and are a crucial element of the carbon cycle, respond to major environmental disturbance. Here, we use a new model ensemble reconstruction of diatom speciation and extinction rates to examine phytoplankton response to climate change in the southern high latitudes over the past 15 My. We identify five major episodes of species turnover (origination rate plus extinction rate) that were coincident with times of cooling in southern high-latitude climate, Antarctic ice sheet growth across the continental shelves, and associated seasonal sea-ice expansion across the Southern Ocean. We infer that past plankton turnover occurred when a warmer-than-present climate was terminated by a major period of glaciation that resulted in loss of open-ocean habitat south of the polar front, driving non-ice adapted diatoms to regional or global extinction. These findings suggest, therefore, that Southern Ocean phytoplankton communities tolerate “baseline” variability on glacial-interglacial timescales but are sensitive to large-scale changes in mean climate state driven by a combination of long-period variations in orbital forcing and atmospheric carbon dioxide perturbations.

A 5000-Fold Increase in the Specificity of a Bacterial Phosphotriesterase for Malathion through Combinatorial Active Site Mutagenesis

PubMed Central

Naqvi, Tatheer; Warden, Andrew C.; French, Nigel; Sugrue, Elena; Carr, Paul D.; Jackson, Colin J.; Scott, Colin

2014-01-01

Phosphotriesterases (PTEs) have been isolated from a range of bacterial species, including Agrobcaterium radiobacter (PTEAr), and are efficient enzymes with broad substrate ranges. The turnover rate of PTEAr for the common organophosphorous insecticide malathion is lower than expected based on its physical properties; principally the pka of its leaving group. In this study, we rationalise the turnover rate of PTEAr for malathion using computational docking of the substrate into a high resolution crystal structure of the enzyme, suggesting that malathion is too large for the PTEAr binding pocket. Protein engineering through combinatorial active site saturation testing (CASTing) was then used to increase the rate of malathion turnover. Variants from a CASTing library in which Ser308 and Tyr309 were mutated yielded variants with increased activity towards malathion. The most active PTEAr variant carried Ser308Leu and Tyr309Ala substitutions, which resulted in a ca. 5000-fold increase in k cat/K M for malathion. X-ray crystal structures for the PTEAr Ser308Leu\\Tyr309Ala variant demonstrate that the access to the binding pocket was enhanced by the replacement of the bulky Tyr309 residue with the smaller alanine residue. PMID:24721933

Threats or violence from patients was associated with turnover intention among foreign-born GPs - a comparison of four workplace factors associated with attitudes of wanting to quit one's job as a GP.

PubMed

Eneroth, Mari; Gustafsson Sendén, Marie; Schenck Gustafsson, Karin; Wall, Maja; Fridner, Ann

2017-06-01

General practitioners (GPs) are crucial in medical healthcare, but there is currently a shortage of GPs in Sweden and elsewhere. Recruitment of GPs from abroad is essential, but foreign-born physicians face difficulties at work that may be related to turnover intention, i.e. wanting to quit one's job. The study aims to explore the reasons to why foreign-born GPs may intend to quit their job. Survey data were used to compare four work-related factors that can be associated with turnover intentions; patient-related stress, threats or violence from patients, control of work pace, and empowering leadership, among native-born and foreign-born GPs. These work-related factors were subsequently examined in relation to turnover intention among the foreign-born GPs by means of linear hierarchical regression analyses. The questionnaire consisted of items from the QPS Nordic and items constructed by the authors. A primary care setting in a central area of Sweden. Native-born (n = 208) and foreign-born GPs (n = 73). Turnover intention was more common among foreign-born GPs (19.2% compared with 14.9%), as was the experience of threats or violence from patients (22% compared with 3% of the native-born GPs). Threats or violence was also associated with increased turnover intention. Control of work pace and an empowering leadership was associated with reduced turnover intention. The organisations need to recognise that foreign-born GPs may face increased rates of threats and/or violence from patients, which may ultimately cause job turnover and be harmful to the exposed individual.

Threats or violence from patients was associated with turnover intention among foreign-born GPs – a comparison of four workplace factors associated with attitudes of wanting to quit one’s job as a GP

PubMed Central

Eneroth, Mari; Gustafsson Sendén, Marie; Schenck Gustafsson, Karin; Wall, Maja; Fridner, Ann

2017-01-01

Objective General practitioners (GPs) are crucial in medical healthcare, but there is currently a shortage of GPs in Sweden and elsewhere. Recruitment of GPs from abroad is essential, but foreign-born physicians face difficulties at work that may be related to turnover intention, i.e. wanting to quit one’s job. The study aims to explore the reasons to why foreign-born GPs may intend to quit their job. Design Survey data were used to compare four work-related factors that can be associated with turnover intentions; patient-related stress, threats or violence from patients, control of work pace, and empowering leadership, among native-born and foreign-born GPs. These work-related factors were subsequently examined in relation to turnover intention among the foreign-born GPs by means of linear hierarchical regression analyses. The questionnaire consisted of items from the QPS Nordic and items constructed by the authors. Setting A primary care setting in a central area of Sweden. Subjects Native-born (n = 208) and foreign-born GPs (n = 73). Results Turnover intention was more common among foreign-born GPs (19.2% compared with 14.9%), as was the experience of threats or violence from patients (22% compared with 3% of the native-born GPs). Threats or violence was also associated with increased turnover intention. Control of work pace and an empowering leadership was associated with reduced turnover intention. Practice implications The organisations need to recognise that foreign-born GPs may face increased rates of threats and/or violence from patients, which may ultimately cause job turnover and be harmful to the exposed individual. PMID:28587508

Substantial Differences between Organ and Muscle Specific Tracer Incorporation Rates in a Lactating Dairy Cow

PubMed Central

Burd, Nicholas A.; Hamer, Henrike M.; Pennings, Bart; Pellikaan, Wilbert F.; Senden, Joan M. G.; Gijsen, Annemie P.; van Loon, Luc J. C.

2013-01-01

We aimed to produce intrinsically L-[1-13C]phenylalanine labeled milk and beef for subsequent use in human nutrition research. The collection of the various organ tissues after slaughter allowed for us to gain insight into the dynamics of tissue protein turnover in vivo in a lactating dairy cow. One lactating dairy cow received a constant infusion of L-[1-13C]phenylalanine (450 µmol/min) for 96 h. Plasma and milk were collected prior to, during, and after the stable isotope infusion. Twenty-four hours after cessation of the infusion the cow was slaughtered. The meat and samples of the various organ tissues (liver, heart, lung, udder, kidney, rumen, small intestine, and colon) were collected and stored. Approximately 210 kg of intrinsically labeled beef (bone and fat free) with an average L-[1-13C]phenylalanine enrichment of 1.8±0.1 mole percent excess (MPE) was obtained. The various organ tissues differed substantially in L-[1-13C]phenylalanine enrichments in the tissue protein bound pool, the highest enrichment levels were achieved in the kidney (11.7 MPE) and the lowest enrichment levels in the skeletal muscle tissue protein of the cow (between 1.5–2.4 MPE). The estimated protein synthesis rates of the various organ tissues should be regarded as underestimates, particularly for the organs with the higher turnover rates and high secretory activity, due to the lengthened (96 h) measurement period necessary for the production of the intrinsically labeled beef. Our data demonstrates that there are relatively small differences in L-[1-13C]phenylalanine enrichments between the various meat cuts, but substantial higher enrichment values are observed in the various organ tissues. We conclude that protein turnover rates of various organs are much higher when compared to skeletal muscle protein turnover rates in large lactating ruminants. PMID:23826365

Factors affecting the estimate of primary production from space

NASA Technical Reports Server (NTRS)

Balch, W. M.; Byrne, C. F.

1994-01-01

Remote sensing of primary production in the euphotic zone has been based mostly on visible-band and water-leaving radiance measured with the coastal zone color scanner. There are some robust, simple relationships for calculating integral production based on surface measurements, but they also require knowledge for photoadaptive parameters such as maximum photosynthesis which currently cannot be obtained from spave. A 17,000-station data set is used to show that space-based estimates of maximum photosynthesis could improve predictions of psi, the water column light utiliztion index, which is an important term in many primary productivity models. Temperature is also examined as a factor for predicting hydrographic structure and primary production. A simple model is used to relate temperature and maximum photosynthesis; the model incorporates (1) the positive relationship between maximum photosynthesis and temperature and (2) the strongly negative relationship between temperature and nitrate in the ocean (which directly affects maximum growth rates via nitrogen limitation). Since these two factors relate to carbon and nitrogen, 'balanced carbon/nitrogen assimilation' was calculated using the Redfield ratio, It is expected that the relationship between maximum balanced carbon assimilation versus temperature is concave-down, with the peak dependent on nitrate uptake kinetics, temperature-nitrate relationships,a nd the carbon chlorophyll ration. These predictions were compared with the sea truth data. The minimum turnover time for nitrate was also calculated using this approach. Lastly, sea surface temperature gradients were used to predict the slope of isotherms (a proxy for the slope of isopycnals in many waters). Sea truth data show that at size scales of several hundred kilometers, surface temperature gradients can provide information on the slope of isotherms in the top 200 m of the water column. This is directly relevant to the supply of nutrients into the surface mixed layer, which is useful for predicting integral biomass and primary production.

Zinc transport in rabbit tissues. Some hormonal aspects of the turnover of zinc in female reproductive organs, liver and body fluids

PubMed Central

McIntosh, J. E. A.; Lutwak-Mann, C.

1972-01-01

1. To investigate the influence of hormonal conditions upon the kinetics of zinc transport, specific radioactivity of 65Zn was determined in certain tissues and fluids from unmated or pregnant rabbits during the first half of gestation. 2. Compartmental analysis was used to find the simplest mathematical model that simulated satisfactorily tracer behaviour. Models were fitted to experimental results by a numerical procedure using a computer. 3. The kinetics of zinc exchange in most tissues investigated could adequately be described by a three-compartment model, in which total tissue zinc content was divided into a rapidly exchanging pool, with a turnover time of about 1h, and a slowly exchanging pool, the turnover time of which was in liver 15h, in peak-stage corpus luteum 8h, and in the other tissues 30–70h. 4. In rabbit endometrium zinc transport varied with hormonal conditions, the turnover rate being higher in non-pregnant than pregnant endometrium. 5. Uptake of 65Zn by uterine fluid was slow, and in the free-lying embryos (blastocysts) slower still, in keeping with uterine fluid acting as carrier of zinc into the unimplanted embryos. 6. In placental tissue zinc transport varied with gestational stage. Foetal placenta exchanged zinc with blood plasma four times faster than maternal placenta. In foetuses zinc turnover time and flux equalled that of the slow zinc compartment in foetal placenta. 7. Corpus luteum on days 5–6 of gestation showed peak specific radioactivity and zinc flux values, which exceeded those of all other tissues. 8. In liver the slow zinc compartment had a higher rate of turnover than corresponding compartments in tissues other than peak-stage corpus luteum, but no hormone-dependent changes were observed. 9. Zinc uptake by erythrocytes was the slowest of all examined. PMID:5073239

The effect of positive interactions on temporal turnover of community composition along an environmental gradient.

PubMed

Wang, Youshi; Yang, Zhiyong; Zhou, Shurong; Soininen, Janne; Ai, Dexiecuo; Li, Yali; Chu, Chengjin

2013-01-01

It has been demonstrated that the interplay between negative and positive interactions simultaneously shapes community structure and composition. However, few studies have attempted to examine the effect of facilitation on compositional changes in communities through time. Additionally, due to the difficulties in collecting the long-term data, it would be useful to indicate the rate of temporal turnover using a readily obtainable metric. Using an individual-based model incorporating plant strategies, we examined the role of facilitation on the temporal turnover of communities located at different positions along an environmental gradient for three model scenarios: CM without facilitation; CFM-U, a unimodal relationship between facilitation and environmental severity; and CFM-L, a positively linear relationship between facilitation and environmental severity. Our results demonstrated that facilitation could increase, decrease or have no remarkable effect on temporal turnover. The specific outcome depended on the location of the focal community across the environmental gradient and the model employed. Compared with CM, the inclusion of positive interactions (i.e. CFM-U and CFM-L), at intermediate environmental stress levels (such as S = 0.7 and 0.8) resulted in lower Bray-Curtis similarity values; at other severity levels, facilitation slowed down (such as S = 0.3 and 0.4 at low to medium stress levels, and S = 0.9 at high stress levels) or had only a subtle effect (such as at S = 0.1) on temporal turnover. We also found that the coefficient of variation (CV) in species abundances and the rate of temporal variability showed a significant quadratic relationship. Our theoretical analysis contributes to the understanding of factors driving temporal turnover in biotic communities, and presents a potential metric (i.e. CV in species abundances) assessing the consequences of ongoing environmental change on community structure.

The Effect of Positive Interactions on Temporal Turnover of Community Composition along an Environmental Gradient

PubMed Central

Wang, Youshi; Yang, Zhiyong; Zhou, Shurong; Soininen, Janne; Ai, Dexiecuo; Li, Yali; Chu, Chengjin

2013-01-01

It has been demonstrated that the interplay between negative and positive interactions simultaneously shapes community structure and composition. However, few studies have attempted to examine the effect of facilitation on compositional changes in communities through time. Additionally, due to the difficulties in collecting the long-term data, it would be useful to indicate the rate of temporal turnover using a readily obtainable metric. Using an individual-based model incorporating plant strategies, we examined the role of facilitation on the temporal turnover of communities located at different positions along an environmental gradient for three model scenarios: CM without facilitation; CFM-U, a unimodal relationship between facilitation and environmental severity; and CFM-L, a positively linear relationship between facilitation and environmental severity. Our results demonstrated that facilitation could increase, decrease or have no remarkable effect on temporal turnover. The specific outcome depended on the location of the focal community across the environmental gradient and the model employed. Compared with CM, the inclusion of positive interactions (i.e. CFM-U and CFM-L), at intermediate environmental stress levels (such as S = 0.7 and 0.8) resulted in lower Bray-Curtis similarity values; at other severity levels, facilitation slowed down (such as S = 0.3 and 0.4 at low to medium stress levels, and S = 0.9 at high stress levels) or had only a subtle effect (such as at S = 0.1) on temporal turnover. We also found that the coefficient of variation (CV) in species abundances and the rate of temporal variability showed a significant quadratic relationship. Our theoretical analysis contributes to the understanding of factors driving temporal turnover in biotic communities, and presents a potential metric (i.e. CV in species abundances) assessing the consequences of ongoing environmental change on community structure. PMID:24265708

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.

Stepwise onset of the Icehouse world and its impact on Oligo-Miocene Central Asian mammals

PubMed Central

Harzhauser, Mathias; Daxner-Höck, Gudrun; López-Guerrero, Paloma; Maridet, Olivier; Oliver, Adriana; Piller, Werner E.; Richoz, Sylvain; Erbajeva, Margarita A.; Neubauer, Thomas A.; Göhlich, Ursula B.

2016-01-01

Central Asia is a key area to study the impact of Cenozoic climate cooling on continental ecosystems. One of the best places to search for rather continuous paleontological records is the Valley of Lakes in Mongolia with its outstandingly fossil-rich Oligocene and Miocene terrestrial sediments. Here, we investigate the response by mammal communities during the early stage of Earth’s icehouse climate in Central Asia. Based on statistical analyses of occurrence and abundance data of 18608 specimens representing 175 mammal species and geochemical (carbon isotopes) and geophysical (magnetic susceptibility) data we link shifts in diversities with major climatic variations. Our data document for the first time that the post-Eocene aridification of Central Asia happened in several steps, was interrupted by short episodes of increased precipitation, and was not a gradual process. We show that the timing of the major turnovers in Oligocene mammal communities is tightly linked with global climate events rather than slow tectonics processes. The most severe decline of up 48% of total diversity is related to aridification during the maximum of the Late Oligocene Warming at 25 Ma. Its magnitude was distinctly larger than the community turnover linked to the mid-Oligocene Glacial Maximum. PMID:27897168

Abrupt turnover in calcareous-nannoplankton assemblages across the Paleocene/Eocene Thermal Maximum: implications for surface-water oligotrophy over the Kerguelen Plateau, Southern Indian Ocean

USGS Publications Warehouse

Jiang, Shijun; Wise, Sherwood W.

2007-01-01

Ocean Drilling Program (ODP) Core Section 183-1135A-25R-4 from the Kerguelen Plateau in the Indian Ocean sector of the Southern Ocean represents only the second complete, expanded sequence through the Paleocene/Eocene Thermal Maximum (PETM; ~55 Ma) recovered from Antarctic waters. Calcareous nannoplankton at this site underwent an abrupt, fundamental turnover across the PETM as defined by a carbon isotope excursion. Although Chiasmolithus, Discoaster, and Fasciculithus exponentially increase in abundance at the onset, the former abruptly drops but then rapidly recovers, whereas the latter two taxa show opposite trends due to surface-water oligotrophy. These observations confirm previous results from ODP Site 690 on Maud Rise. The elevated pCO2 that accompanied the PETM caused a shoaling of the lysocline and carbonate compensation depth, leading to intensive dissolution of susceptible holococcoliths and poor preservation of the assemblages. Similarities and contrasts between the results of this study and previous work from open-ocean sites and shelf margins further demonstrate that the response to the PETM was consistent in open-ocean environments, but could be localized on continental shelves where nutrient regimes depend on the local geologic setting and oceanographic conditions.

Index Fund Selections with GAs and Classifications Based on Turnover

NASA Astrophysics Data System (ADS)

Orito, Yukiko; Motoyama, Takaaki; Yamazaki, Genji

It is well known that index fund selections are important for the risk hedge of investment in a stock market. The`selection’means that for`stock index futures’, n companies of all ones in the market are selected. For index fund selections, Orito et al.(6) proposed a method consisting of the following two steps : Step 1 is to select N companies in the market with a heuristic rule based on the coefficient of determination between the return rate of each company in the market and the increasing rate of the stock price index. Step 2 is to construct a group of n companies by applying genetic algorithms to the set of N companies. We note that the rule of Step 1 is not unique. The accuracy of the results using their method depends on the length of time data (price data) in the experiments. The main purpose of this paper is to introduce a more`effective rule’for Step 1. The rule is based on turnover. The method consisting of Step 1 based on turnover and Step 2 is examined with numerical experiments for the 1st Section of Tokyo Stock Exchange. The results show that with our method, it is possible to construct the more effective index fund than the results of Orito et al.(6). The accuracy of the results using our method depends little on the length of time data (turnover data). The method especially works well when the increasing rate of the stock price index over a period can be viewed as a linear time series data.

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.

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.

Differential effects of dietary fats on sympathetic nervous system activity in the rat.

PubMed

Young, J B; Walgren, M C

1994-01-01

Fat feeding stimulates sympathetic nervous system (SNS) activity in rats. To determine if fats vary in their potency as stimulants of the SNS, [3H]norepinephrine ([3H]NE) turnover was measured in heart and interscapular brown adipose tissue (IBAT) of animals fed lab chow diets supplemented with safflower oil, coconut oil, or medium-chain triglycerides (MCT). At 5 days, all three fats accelerated [3H]NE turnover in heart and did so equally, but only when the fat supplement represented an increase in energy intake. However, after 14 days, safflower oil and coconut oil but not MCT increased [3H]NE turnover in heart compared with turnover rates obtained in animals fed isoenergetic amounts of chow. Furthermore, the stimulatory effect of safflower oil on [3H]NE turnover was statistically greater than that seen in animals fed equivalent amounts of coconut oil. In vivo synthesis of NE assessed by accumulation of dopamine (DA) in heart following inhibition of dopamine-beta-hydroxylase (D beta H) was likewise highest in safflower oil-fed rats and lowest in those fed MCT. Thus, sympathetic activation by dietary fat varies among different fats, suggesting a role for fatty acid intake in dietary regulation of the SNS.

Influence of topical anesthesia on tear dynamics and ocular drug bioavailability in albino rabbits.

PubMed

Patton, T F; Robinson, J R

1975-02-01

The bioavailability of topically applied ocular drugs is very poor, due largely to drug loss through drainage and tear turnover. The use of high viscosity solutions or solid matrixes to delay or eliminate drainage is the usual approach for decreasing drug loss but the alternative approach of chemically reducing tear turnover and/or solution drainage has not been investigated. By means of a simple isotopic dilution technique, using radioactive technetium sulfur colloid, the quantitative influence of topical anesthetics on tear production and instilled solution drainage was determined. The reduction in the rate of tear turnover and solution drainage varies for different anesthetics and is dose dependent. The implication of these results for some long accepted clinical procedures is discussed, and questions are raised regarding the present understanding of the mechanisms of tear production. Quantitation of precorneal drug loss through instilled solution drainage and tear turnover permits the establishment of a baseline for ocular drug bioavailability. Aqueous humor drug concentration versus time profiles of radioactive pilocarpine nitrate were obtained, both in the presence and absence of topical anesthesia. The results verify the importance of tear turnover and instilled solution drainage as a major route of drug loss in the eye. Moreover, the success of the present study in improving ocular drug bioavailability by the chemical approach of repressing solution drainage and tear turnover suggests that this approach is viable for improving drug bioavailability.

The effect of nurse manager turnover on patient fall and pressure ulcer rates.

PubMed

Warshawsky, Nora; Rayens, Mary Kay; Stefaniak, Karen; Rahman, Rana

2013-07-01

The purpose of this study was to explore the effects of nurse manager turnover on the occurrence of adverse events. Nurse managers create professional nurse practice environments to support the provision of quality patient outcomes. Inconsistent findings were reported in the literature testing the relationship between nurse managers and patient outcomes. All prior studies assumed stable nursing management. A longitudinal quasi-experimental study of 23 nursing units in two hospitals was used to determine whether unit characteristics, including nurse manager turnover, have an effect on patient falls or pressure ulcers. Statistical analyses included repeated measures and hierarchical modelling. Patients in medical/surgical units experienced more falls than in intensive care units (F1,11 = 15.9, P = 0.002). Patients in units with a nurse manager turnover [odds ratio: 3.16; 95% confidence interval: 1.49-6.70] and intensive care units (odds ratio: 2.70; 95% confidence interval: 1.33-5.49) were more likely to develop pressure ulcers. Nurse manager turnover and intensive care unit status were associated with more pressure ulcers. Medical/surgical unit status was associated with more falls. The study was limited by a small sample size. Nurse manager turnover may negatively impact patient outcomes. Stable nursing management, strategic interim management and long-term succession planning may reduce adverse patient events. © 2013 John Wiley & Sons Ltd.

Nurse turnover in substance abuse treatment programs affiliated with the National Drug Abuse Treatment Clinical Trials Network.

PubMed

Knudsen, Hannah K; Abraham, Amanda J; Roman, Paul M; Studts, Jamie L

2011-04-01

Voluntary nurse turnover, which is costly and disrupts patient care, has not been studied as an organizational phenomenon within substance abuse treatment organizations. In this exploratory study, we examined the frequency and correlates of nurse turnover within treatment programs affiliated with the National Drug Abuse Treatment Clinical Trials Network. During face-to-face interviews conducted in 2005-2006, 215 program administrators reported the number of nurses currently employed. Leaders of programs with nursing staff then described the number of nurses who had voluntarily quit in the past year, the degree to which filling vacant nursing positions was difficult, and the average number of days to fill a vacant position. About two thirds of these programs had at least one nurse on staff. In programs with nurses, the average rate of voluntary turnover was 15.0%. Turnover was significantly lower in hospital-based programs and programs offering adolescent treatment but higher in facilities offering residential treatment. Most of the administrators indicated that filling vacant nurse positions was difficult and took more than 2 months to complete. These findings suggest that nurse turnover is a significant issue facing many substance abuse treatment facilities. Efforts to improve retention of the addiction treatment workforce should be expanded to include nursing professionals. Copyright © 2011 Elsevier Inc. All rights reserved.

Developing a Personnel Capacity Indicator for a high turnover Cartographic Production Sector

NASA Astrophysics Data System (ADS)

Mandarino, Flávia; Pessôa, Leonardo A. M.

2018-05-01

This paper describes a framework for development of an indicator for human re-sources capacity management in a military organization responsible for nautical chart production. Graphic chart for the results of the model COPPE-COSENZA (Cosenza et al. 2015) is used to properly present the personnel capacity within a high people turnover environment. The specific skills for the nautical charts production allied to the turnover rate require continuous and adequate personnel in-corporation and a capacity building through education and on-the-job training. The adopted approach for the study establishes quantitative values to fulfill quality requirements, and also presents graphically a profile for the human resources on a specific job to facilitate diagnosis and corrective actions.

Drought-induced changes in Amazon forest structure from repeat airborne lidar

NASA Astrophysics Data System (ADS)

Morton, D. C.; Leitold, V.; Longo, M.; Keller, M.; dos-Santos, M. N.; Scaranello, M. A., Sr.

2017-12-01

Drought events in tropical forests, including the 2015-2016 El Niño, may reduce net primary productivity and increase canopy tree mortality, thereby altering the short and long-term net carbon balance of tropical forests. Given the broad extent of drought impacts, forest inventory plots or eddy flux towers may not capture regional variability in forest response to drought. Here, we analyzed repeat airborne lidar data to evaluate canopy turnover from branch and tree fall before (2013-2014) and during (2014-2016) the recent El Niño drought in the eastern and central Brazilian Amazon. Coincident field surveys for a 16-ha subset of the lidar coverage provided complementary information to classify turnover areas by mechanism (branch, multiple branch, tree fall, multiple tree fall) and estimate the total coarse woody debris volume from canopy and understory tree mortality. Annualized rates of canopy turnover increased by 50%, on average, during the drought period in both intact and fragmented forests near Santarém, Pará. Turnover increased uniformly across all size classes, and there was limited evidence that taller trees contributed a greater proportion of turnover events in any size class in 2014-2016 compared to 2013-2014. This short-term increase in canopy turnover differs from findings in multi-year rainfall exclusion experiments that large trees were more sensitive to drought impacts. Field measurements confirmed the separability of the smallest (single branch) and largest damage classes (multiple tree falls), but single tree and multiple branch fall events generated similar coarse woody debris production and lidar-derived changes in canopy volume. Large-scale sampling possible with repeat airborne lidar data also captured strong local and regional gradients in canopy turnover. Differences in slope partially explained the north-south gradient in canopy turnover dynamics near Santarém, with larger increases in turnover on flatter terrain. Regional variability in canopy turnover in response to drought conditions highlights the need for a mechanistic representation of branch and tree fall dynamics in ecosystem models to resolve changes in net carbon balance from the increase in coarse woody debris production and reorganization of canopy light environments during drought years.

Job satisfaction, burnout and turnover intention in occupational therapists working in mental health.

PubMed

Scanlan, Justin Newton; Still, Megan

2013-10-01

Employee wellbeing is an important issue for mental health services. Poor employee wellbeing (i.e., high levels of burnout or low job satisfaction) is associated with poorer consumer outcomes and higher staff turnover. This study set out to examine factors related to job satisfaction, turnover intention and burnout in a group of occupational therapists in mental health. Thirty-four occupational therapists (response rate approximately 60%) in a metropolitan public mental health service participated in a whole-of-service workforce survey. The survey included measures of job satisfaction, turnover intention, burnout, job hindrances, job challenges and job resources and questions about positive and negative aspects of positions and factors that attracted employees to their current position. Burnout was associated with lower job satisfaction and higher turnover intention. Higher job satisfaction was associated with rewards (remuneration and recognition) as well as cognitively challenging work. The variables most significantly associated with poorer wellbeing (higher turnover intention and burnout) were recipient contact demands (perception that contact with service users or families was demanding), and feelings of stress or fatigue. This study provides a detailed analysis of factors associated with job satisfaction, turnover intention and burnout in a group of occupational therapists working in mental health. To promote workforce wellbeing and enhanced retention, interventions to minimise burnout should be implemented and evaluated. These strategies should focus on enhancing job resources such as supervisor support, feedback and participation in decision making as well as building the personal resilience of occupational therapists working in mental health. © 2013 Occupational Therapy Australia.

Energy economy in the actomyosin interaction: lessons from simple models.

PubMed

Lehman, Steven L

2010-01-01

The energy economy of the actomyosin interaction in skeletal muscle is both scientifically fascinating and practically important. This chapter demonstrates how simple cross-bridge models have guided research regarding the energy economy of skeletal muscle. Parameter variation on a very simple two-state strain-dependent model shows that early events in the actomyosin interaction strongly influence energy efficiency, and late events determine maximum shortening velocity. Addition of a weakly-bound state preceding force production allows weak coupling of cross-bridge mechanics and ATP turnover, so that a simple three-state model can simulate the velocity-dependence of ATP turnover. Consideration of the limitations of this model leads to a review of recent evidence regarding the relationship between ligand binding states, conformational states, and macromolecular structures of myosin cross-bridges. Investigation of the fine structure of the actomyosin interaction during the working stroke continues to inform fundamental research regarding the energy economy of striated muscle.

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.

Mitochondrial Respiratory Defect Causes Dysfunctional Lactate Turnover via AMP-activated Protein Kinase Activation in Human-induced Pluripotent Stem Cell-derived Hepatocytes*

PubMed Central

Im, Ilkyun; Jang, Mi-jin; Park, Seung Ju; Lee, Sang-Hee; Choi, Jin-Ho; Yoo, Han-Wook; Kim, Seyun; Han, Yong-Mahn

2015-01-01

A defective mitochondrial respiratory chain complex (DMRC) causes various metabolic disorders in humans. However, the pathophysiology of DMRC in the liver remains unclear. To understand DMRC pathophysiology in vitro, DMRC-induced pluripotent stem cells were generated from dermal fibroblasts of a DMRC patient who had a homoplasmic mutation (m.3398T→C) in the mitochondrion-encoded NADH dehydrogenase 1 (MTND1) gene and that differentiated into hepatocytes (DMRC hepatocytes) in vitro. DMRC hepatocytes showed abnormalities in mitochondrial characteristics, the NAD+/NADH ratio, the glycogen storage level, the lactate turnover rate, and AMPK activity. Intriguingly, low glycogen storage and transcription of lactate turnover-related genes in DMRC hepatocytes were recovered by inhibition of AMPK activity. Thus, AMPK activation led to metabolic changes in terms of glycogen storage and lactate turnover in DMRC hepatocytes. These data demonstrate for the first time that energy depletion may lead to lactic acidosis in the DMRC patient by reduction of lactate uptake via AMPK in liver. PMID:26491018

Retaining your high performers: moderators of the performance-job satisfaction-voluntary turnover relationship.

PubMed

Nyberg, Anthony

2010-05-01

Two divergent ideas explain the relationship between performance and voluntary turnover. One suggests that higher performing employees, who are rewarded for their superior work product, will desire to remain with an organization that values their performance and will, consequently, be less likely than lower performing employees to voluntarily leave. An alternative idea suggests that higher performing employees, who are more desirable to external companies as a result of their superior work product, will have more external job opportunities and will, consequently, be more likely than their lower performing colleagues to voluntarily leave. The current study evaluated the behaviors and attitudes of 12,545 insurance employees over a 3-year period to examine how these 2 divergent expectations influence the performance-voluntary turnover relationship. Results show that both pay growth and the relevant unemployment rate interact with performance to influence the performance-voluntary turnover relationship and that they work independently of employee job satisfaction influences. PsycINFO Database Record (c) 2010 APA, all rights reserved.

Mean field study of a propagation-turnover lattice model for the dynamics of histone marking

NASA Astrophysics Data System (ADS)

Yao, Fan; Li, FangTing; Li, TieJun

2017-02-01

We present a mean field study of a propagation-turnover lattice model, which was proposed by Hodges and Crabtree [Proc. Nat. Acad. Sci. 109, 13296 (2012)] for understanding how posttranslational histone marks modulate gene expression in mammalian cells. The kinetics of the lattice model consists of nucleation, propagation and turnover mechanisms, and exhibits second-order phase transition for the histone marking domain. We showed rigorously that the dynamics essentially depends on a non-dimensional parameter κ = k +/ k -, the ratio between the propagation and turnover rates, which has been observed in the simulations. We then studied the lowest order mean field approximation, and observed the phase transition with an analytically obtained critical parameter. The boundary layer analysis was utilized to investigate the structure of the decay profile of the mark density. We also studied the higher order mean field approximation to achieve sharper estimate of the critical transition parameter and more detailed features. The comparison between the simulation and theoretical results shows the validity of our theory.

Cobalt-Catalyzed C(sp(2))-H Borylation: Mechanistic Insights Inspire Catalyst Design.

PubMed

Obligacion, Jennifer V; Semproni, Scott P; Pappas, Iraklis; Chirik, Paul J

2016-08-24

A comprehensive study into the mechanism of bis(phosphino)pyridine (PNP) cobalt-catalyzed C-H borylation of 2,6-lutidine using B2Pin2 (Pin = pinacolate) has been conducted. The experimentally observed rate law, deuterium kinetic isotope effects, and identification of the catalyst resting state support turnover limiting C-H activation from a fully characterized cobalt(I) boryl intermediate. Monitoring the catalytic reaction as a function of time revealed that borylation of the 4-position of the pincer in the cobalt catalyst was faster than arene borylation. Cyclic voltammetry established the electron withdrawing influence of 4-BPin, which slows the rate of C-H oxidative addition and hence overall catalytic turnover. This mechanistic insight inspired the next generation of 4-substituted PNP cobalt catalysts with electron donating and sterically blocking methyl and pyrrolidinyl substituents that exhibited increased activity for the C-H borylation of unactivated arenes. The rationally designed catalysts promote effective turnover with stoichiometric quantities of arene substrate and B2Pin2. Kinetic studies on the improved catalyst, 4-(H)2BPin, established a change in turnover limiting step from C-H oxidative addition to C-B reductive elimination. The iridium congener of the optimized cobalt catalyst, 6-(H)2BPin, was prepared and crystallographically characterized and proved inactive for C-H borylation, a result of the high kinetic barrier for reductive elimination from octahedral Ir(III) complexes.

Long-term sensitivity of soil carbon turnover to warming.

PubMed

Knorr, W; Prentice, I C; House, J I; Holland, E A

2005-01-20

The sensitivity of soil carbon to warming is a major uncertainty in projections of carbon dioxide concentration and climate. Experimental studies overwhelmingly indicate increased soil organic carbon (SOC) decomposition at higher temperatures, resulting in increased carbon dioxide emissions from soils. However, recent findings have been cited as evidence against increased soil carbon emissions in a warmer world. In soil warming experiments, the initially increased carbon dioxide efflux returns to pre-warming rates within one to three years, and apparent carbon pool turnover times are insensitive to temperature. It has already been suggested that the apparent lack of temperature dependence could be an artefact due to neglecting the extreme heterogeneity of soil carbon, but no explicit model has yet been presented that can reconcile all the above findings. Here we present a simple three-pool model that partitions SOC into components with different intrinsic turnover rates. Using this model, we show that the results of all the soil-warming experiments are compatible with long-term temperature sensitivity of SOC turnover: they can be explained by rapid depletion of labile SOC combined with the negligible response of non-labile SOC on experimental timescales. Furthermore, we present evidence that non-labile SOC is more sensitive to temperature than labile SOC, implying that the long-term positive feedback of soil decomposition in a warming world may be even stronger than predicted by global models.

Effect of collagen turnover on the accumulation of advanced glycation end products.

PubMed

Verzijl, N; DeGroot, J; Thorpe, S R; Bank, R A; Shaw, J N; Lyons, T J; Bijlsma, J W; Lafeber, F P; Baynes, J W; TeKoppele, J M

2000-12-15

Collagen molecules in articular cartilage have an exceptionally long lifetime, which makes them susceptible to the accumulation of advanced glycation end products (AGEs). In fact, in comparison to other collagen-rich tissues, articular cartilage contains relatively high amounts of the AGE pentosidine. To test the hypothesis that this higher AGE accumulation is primarily the result of the slow turnover of cartilage collagen, AGE levels in cartilage and skin collagen were compared with the degree of racemization of aspartic acid (% d-Asp, a measure of the residence time of a protein). AGE (N(epsilon)-(carboxymethyl)lysine, N(epsilon)-(carboxyethyl)lysine, and pentosidine) and % d-Asp concentrations increased linearly with age in both cartilage and skin collagen (p < 0.0001). The rate of increase in AGEs was greater in cartilage collagen than in skin collagen (p < 0.0001). % d-Asp was also higher in cartilage collagen than in skin collagen (p < 0.0001), indicating that cartilage collagen has a longer residence time in the tissue, and thus a slower turnover, than skin collagen. In both types of collagen, AGE concentrations increased linearly with % d-Asp (p < 0.0005). Interestingly, the slopes of the curves of AGEs versus % d-Asp, i.e. the rates of accumulation of AGEs corrected for turnover, were identical for cartilage and skin collagen. The present study thus provides the first experimental evidence that protein turnover is a major determinant in AGE accumulation in different collagen types. From the age-related increases in % d-Asp the half-life of cartilage collagen was calculated to be 117 years and that of skin collagen 15 years, thereby providing the first reasonable estimates of the half-lives of these collagens.

2H2O-Based HDL Turnover Method for the Assessment of Dynamic HDL Function in Mice

PubMed Central

Kasumov, Takhar; Willard, Belinda; Li, Ling; Li, Min; Conger, Heather; Buffa, Jennifer A.; Previs, Stephen; McCullough, Arthur; Hazen, Stanley L.; Smith, Jonathan D.

2014-01-01

Objective High-density lipoprotein (HDL) promotes reverse cholesterol transport (RCT) from peripheral tissues to the liver for clearance. Reduced HDL-cholesterol (HDLc) is associated with atherosclerosis; however, as a predictor of cardiovascular disease, HDLc has limitations as it is not a direct marker of HDL functionality. Our objective was to develop a mass spectrometry based method for the simultaneous measurement of HDLc and ApoAI kinetics in mice using a single 2H2O tracer, and use it to examine genetic and drug perturbations on HDL turnover in vivo. Approach and Results Mice were given 2H2O in the drinking water and serial blood samples were collected at different time points. HDLc and ApoAI gradually incorporated 2H, allowing experimental measurement of fractional catabolic rates (FCR) and production rates (PR) for HDLc and ApoA1. ApoE−/− mice displayed increased FCR (p<0.01) and reduced PR of both HDLc and ApoAI (p<0.05) compared to controls. In human ApoAI transgenic mice, levels and PRs of HDLc and human ApoAI were strikingly higher than in wild type mice. Myriocin, an inhibitor of sphingolipid synthesis, significantly increased both HDL flux and macrophage-to-feces RCT, indicating compatibility of this HDL turnover method with the macrophage specific RCT assay. Conclusions 2H2O-labeling can be used to measure HDLc and ApoAI flux in vivo, and to assess the role of genetic and pharmacological interventions on HDL turnover in mice. Safety, simplicity, and low cost of the 2H2O-based HDL turnover approach suggest that this assay can be scaled for human use to study effects of HDL targeted therapies on dynamic HDL function. PMID:23766259

Paleoclimate determines diversification patterns in the fossorial snake family Uropeltidae Cuvier, 1829.

PubMed

Cyriac, Vivek Philip; Kodandaramaiah, Ullasa

2017-11-01

Understanding how and why diversification rates vary across evolutionary time is central to understanding how biodiversity is generated and maintained. Recent mathematical models that allow estimation of diversification rates across time from reconstructed phylogenies have enabled us to make inferences on how biodiversity copes with environmental change. Here, we explore patterns of temporal diversification in Uropeltidae, a diverse fossorial snake family. We generate a time-calibrated phylogenetic hypothesis for Uropeltidae and show a significant correlation between diversification rate and paleotemperature during the Cenozoic. We show that the temporal diversification pattern of this group is punctuated by one rate shift event with a decrease in diversification and turnover rate between ca. 11Ma to present, but there is no strong support for mass extinction events. The analysis indicates higher turnover during periods of drastic climatic fluctuations and reduced diversification rates associated with contraction and fragmentation of forest habitats during the late Miocene. Our study highlights the influence of environmental fluctuations on diversification rates in fossorial taxa such as uropeltids, and raises conservation concerns related to present rate of climate change. Copyright © 2017 Elsevier Inc. All rights reserved.

Solvated molecular dynamics of LiCN isomerization: All-atom argon solvent versus a generalized Langevin bath.

PubMed

Junginger, Andrej; Garcia-Muller, Pablo L; Borondo, F; Benito, R M; Hernandez, Rigoberto

2016-01-14

The reaction rate rises and falls with increasing density or friction when a molecule is activated by collisions with the solvent particles. This so-called Kramers turnover has recently been observed in the isomerization reaction of LiCN in an argon bath. In this paper, we demonstrate by direct comparison with those results that a reduced-dimensional (generalized) Langevin description gives rise to similar reaction dynamics as the corresponding (computationally expensive) full molecular dynamics calculations. We show that the density distributions within the Langevin description are in direct agreement with the full molecular dynamics results and that the turnover in the reaction rates is reproduced qualitatively and quantitatively at different temperatures.

Dynamic phenotypic restructuring of the CD4 and CD8 T-cell subsets with age in healthy humans: a compartmental model analysis.

PubMed

Jackola, D R; Hallgren, H M

1998-11-16

In healthy humans, phenotypic restructuring occurs with age within the CD3+ T-lymphocyte complement. This is characterized by a non-linear decrease of the percentage of 'naive' (CD45RA+) cells and a corresponding non-linear increase of the percentage of 'memory' (CD45R0+) cells among both the CD4+ and CD8+ T-cell subsets. We devised a simple compartmental model to study the age-dependent kinetics of phenotypic restructuring. We also derived differential equations whose parameters determined yearly gains minus losses of the percentage and absolute numbers of circulating naive cells, yearly gains minus losses of the percentage and absolute numbers of circulating memory cells, and the yearly rate of conversion of naive to memory cells. Solutions of these evaluative differential equations demonstrate the following: (1) the memory cell complement 'resides' within its compartment for a longer time than the naive cell complement within its compartment for both CD4 and CD8 cells; (2) the average, annual 'turnover rate' is the same for CD4 and CD8 naive cells. In contrast, the average, annual 'turnover rate' for memory CD8 cells is 1.5 times that of memory CD4 cells; (3) the average, annual conversion rate of CD4 naive cells to memory cells is twice that of the CD8 conversion rate; (4) a transition in dynamic restructuring occurs during the third decade of life that is due to these differences in turnover and conversion rates, between and from naive to memory cells.

Critical Role for Monocytes/Macrophages in Rapid Progression to AIDS in Pediatric Simian Immunodeficiency Virus-Infected Rhesus Macaques.

PubMed

Sugimoto, Chie; Merino, Kristen M; Hasegawa, Atsuhiko; Wang, Xiaolei; Alvarez, Xavier A; Wakao, Hiroshi; Mori, Kazuyasu; Kim, Woong-Ki; Veazey, Ronald S; Didier, Elizabeth S; Kuroda, Marcelo J

2017-09-01

Infant humans and rhesus macaques infected with the human or simian immunodeficiency virus (HIV or SIV), respectively, express higher viral loads and progress more rapidly to AIDS than infected adults. Activated memory CD4 + T cells in intestinal tissues are major primary target cells for SIV/HIV infection, and massive depletion of these cells is considered a major cause of immunodeficiency. Monocytes and macrophages are important cells of innate immunity and also are targets of HIV/SIV infection. We reported previously that a high peripheral blood monocyte turnover rate was predictive for the onset of disease progression to AIDS in SIV-infected adult macaques. The purpose of this study was to determine if earlier or higher infection of monocytes/macrophages contributes to the more rapid progression to AIDS in infants. We observed that uninfected infant rhesus macaques exhibited higher physiologic baseline monocyte turnover than adults. Early after SIV infection, the monocyte turnover further increased, and it remained high during progression to AIDS. A high percentage of terminal deoxynucleotidyltransferase dUTP nick end label (TUNEL)-positive macrophages in the lymph nodes (LNs) and intestine corresponded with an increasing number of macrophages derived from circulating monocytes (bromodeoxyuridine positive [BrdU + ] CD163 + ), suggesting that the increased blood monocyte turnover was required to rapidly replenish destroyed tissue macrophages. Immunofluorescence analysis further demonstrated that macrophages were a significant portion of the virus-producing cells found in LNs, intestinal tissues, and lungs. The higher baseline monocyte turnover in infant macaques and subsequent macrophage damage by SIV infection may help explain the basis of more rapid disease progression to AIDS in infants. IMPORTANCE HIV infection progresses much more rapidly in pediatric cases than in adults; however, the mechanism for this difference is unclear. Using the rhesus macaque model, this work was performed to address why infants infected with SIV progress more quickly to AIDS than do adults. Earlier we reported that in adult rhesus macaques, increasing monocyte turnover reflected tissue macrophage damage by SIV and was predictive of terminal disease progression to AIDS. Here we report that uninfected infant rhesus macaques exhibited a higher physiological baseline monocyte turnover rate than adults. Furthermore, once infected with SIV, infants displayed further increased monocyte turnover that may have facilitated the accelerated progression to AIDS. These results support a role for monocytes and macrophages in the pathogenesis of SIV/HIV and begin to explain why infants are more prone to rapid disease progression. Copyright © 2017 American Society for Microbiology.

Critical Role for Monocytes/Macrophages in Rapid Progression to AIDS in Pediatric Simian Immunodeficiency Virus-Infected Rhesus Macaques

PubMed Central

Sugimoto, Chie; Merino, Kristen M.; Hasegawa, Atsuhiko; Wang, Xiaolei; Alvarez, Xavier A.; Wakao, Hiroshi; Kim, Woong-Ki; Veazey, Ronald S.; Didier, Elizabeth S.

2017-01-01

ABSTRACT Infant humans and rhesus macaques infected with the human or simian immunodeficiency virus (HIV or SIV), respectively, express higher viral loads and progress more rapidly to AIDS than infected adults. Activated memory CD4+ T cells in intestinal tissues are major primary target cells for SIV/HIV infection, and massive depletion of these cells is considered a major cause of immunodeficiency. Monocytes and macrophages are important cells of innate immunity and also are targets of HIV/SIV infection. We reported previously that a high peripheral blood monocyte turnover rate was predictive for the onset of disease progression to AIDS in SIV-infected adult macaques. The purpose of this study was to determine if earlier or higher infection of monocytes/macrophages contributes to the more rapid progression to AIDS in infants. We observed that uninfected infant rhesus macaques exhibited higher physiologic baseline monocyte turnover than adults. Early after SIV infection, the monocyte turnover further increased, and it remained high during progression to AIDS. A high percentage of terminal deoxynucleotidyltransferase dUTP nick end label (TUNEL)-positive macrophages in the lymph nodes (LNs) and intestine corresponded with an increasing number of macrophages derived from circulating monocytes (bromodeoxyuridine positive [BrdU+] CD163+), suggesting that the increased blood monocyte turnover was required to rapidly replenish destroyed tissue macrophages. Immunofluorescence analysis further demonstrated that macrophages were a significant portion of the virus-producing cells found in LNs, intestinal tissues, and lungs. The higher baseline monocyte turnover in infant macaques and subsequent macrophage damage by SIV infection may help explain the basis of more rapid disease progression to AIDS in infants. IMPORTANCE HIV infection progresses much more rapidly in pediatric cases than in adults; however, the mechanism for this difference is unclear. Using the rhesus macaque model, this work was performed to address why infants infected with SIV progress more quickly to AIDS than do adults. Earlier we reported that in adult rhesus macaques, increasing monocyte turnover reflected tissue macrophage damage by SIV and was predictive of terminal disease progression to AIDS. Here we report that uninfected infant rhesus macaques exhibited a higher physiological baseline monocyte turnover rate than adults. Furthermore, once infected with SIV, infants displayed further increased monocyte turnover that may have facilitated the accelerated progression to AIDS. These results support a role for monocytes and macrophages in the pathogenesis of SIV/HIV and begin to explain why infants are more prone to rapid disease progression. PMID:28566378

Generalized theory on the mechanism of site-specific DNA-protein interactions

NASA Astrophysics Data System (ADS)

Niranjani, G.; Murugan, R.

2016-05-01

We develop a generalized theoretical framework on the binding of transcription factor proteins (TFs) with specific sites on DNA that takes into account the interplay of various factors regarding overall electrostatic potential at the DNA-protein interface, occurrence of kinetic traps along the DNA sequence, presence of other roadblock protein molecules along DNA and crowded environment, conformational fluctuations in the DNA binding domains (DBDs) of TFs, and the conformational state of the DNA. Starting from a Smolochowski type theoretical framework on site-specific binding of TFs we logically build our model by adding the effects of these factors one by one. Our generalized two-step model suggests that the electrostatic attractive forces present inbetween the positively charged DBDs of TFs and the negatively charged phosphate backbone of DNA, along with the counteracting shielding effects of solvent ions, is the core factor that creates a fluidic type environment at the DNA-protein interface. This in turn facilitates various one-dimensional diffusion (1Dd) processes such as sliding, hopping and intersegmental transfers. These facilitating processes as well as flipping dynamics of conformational states of DBDs of TFs between stationary and mobile states can enhance the 1Dd coefficient on a par with three-dimensional diffusion (3Dd). The random coil conformation of DNA also plays critical roles in enhancing the site-specific association rate. The extent of enhancement over the 3Dd controlled rate seems to be directly proportional to the maximum possible 1Dd length. We show that the overall site-specific binding rate scales with the length of DNA in an asymptotic way. For relaxed DNA, the specific binding rate will be independent of the length of DNA as length increases towards infinity. For condensed DNA as in in vivo conditions, the specific binding rate depends on the length of DNA in a turnover way with a maximum. This maximum rate seems to scale with the maximum possible 1Dd length of TFs in a square root manner. Results suggest that 1Dd processes contribute much less to the enhancement of specific binding rate under in vivo conditions for condensed DNA. There exists a critical length of binding stretch of TFs beyond which the probability associated with the random occurrence of similar specific binding sites will be close to zero. TFs in natural systems from prokaryotes to eukaryotes seem to handle sequence-mediated kinetic traps via increasing the length of their recognition stretch or combinatorial binding. TFs overcome the hurdles of roadblocks via switching efficiently between sliding, hopping and intersegmental transfer modes. The site-specific binding rate as well as the maximum possible 1Dd length seem to be directly proportional to the square root of the probability (p R) of finding a nonspecific binding site to be free from dynamic roadblocks. Here p R seems to be a function of the number of nsbs available per DNA binding protein (ϕ) inside the living cell. It seems that p R  >  0.8 when ϕ  >  10 which is true for the Escherichia coli cell system.

Anxiolytic-like effect of inhalation of essential oil from Lavandula officinalis: investigation of changes in 5-HT turnover and involvement of olfactory stimulation.

PubMed

Takahashi, Mizuho; Yamanaka, Ayako; Asanuma, Chihiro; Asano, Hiroko; Satou, Tadaaki; Koike, Kazuo

2014-07-01

Essential oil extracted from Lavandula officinalis (LvEO) has a long history of usage in anxiety alleviation with good evidence to support its use. However, findings and information regarding the exact pathway involved and mechanism of action remain inconclusive. Therefore, we aimed to (1) reveal the influence of olfactory stimulation, and (2) determine whether the serotonergic system is involved in the anxiolytic effect of LvEO when it is inhaled. To this end, we first compared the anxiety-related behaviors of normosmic and anosmic mice. LvEO inhalation caused notable elevation in anxiety-related parameters with or without olfactory perception, indicating that olfactory stimulation is not necessarily required for LvEO to be effective. Neurochemical analysis of the serotonin (5-HT) turnover rate, accompanied by EPM testing, was then performed. LvEO significantly increased the striatal and hippocampal levels of 5-HT and decreased turnover rates in accordance with the anxiolytic behavioral changes. These results, together with previous findings, support the hypothesis that serotonergic neurotransmission plays a certain role in the anxiolytic properties of LvEO.

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.

Improving a natural enzyme activity through incorporation of unnatural amino acids.

PubMed

Ugwumba, Isaac N; Ozawa, Kiyoshi; Xu, Zhi-Qiang; Ely, Fernanda; Foo, Jee-Loon; Herlt, Anthony J; Coppin, Chris; Brown, Sue; Taylor, Matthew C; Ollis, David L; Mander, Lewis N; Schenk, Gerhard; Dixon, Nicholas E; Otting, Gottfried; Oakeshott, John G; Jackson, Colin J

2011-01-19

The bacterial phosphotriesterases catalyze hydrolysis of the pesticide paraoxon with very fast turnover rates and are thought to be near to their evolutionary limit for this activity. To test whether the naturally evolved turnover rate could be improved through the incorporation of unnatural amino acids and to probe the role of peripheral active site residues in nonchemical steps of the catalytic cycle (substrate binding and product release), we replaced the naturally occurring tyrosine amino acid at position 309 with unnatural L-(7-hydroxycoumarin-4-yl)ethylglycine (Hco) and L-(7-methylcoumarin-4-yl)ethylglycine amino acids, as well as leucine, phenylalanine, and tryptophan. Kinetic analysis suggests that the 7-hydroxyl group of Hco, particularly in its deprotonated state, contributes to an increase in the rate-limiting product release step of substrate turnover as a result of its electrostatic repulsion of the negatively charged 4-nitrophenolate product of paraoxon hydrolysis. The 8-11-fold improvement of this already highly efficient catalyst through a single rationally designed mutation using an unnatural amino acid stands in contrast to the difficulty in improving this native activity through screening hundreds of thousands of mutants with natural amino acids. These results demonstrate that designer amino acids provide easy access to new and valuable sequence and functional space for the engineering and evolution of existing enzyme functions.

Dead wood biomass and turnover time, measured by radiocarbon, along a subalpine elevation gradient.

PubMed

Kueppers, Lara M; Southon, John; Baer, Paul; Harte, John

2004-12-01

Dead wood biomass can be a substantial fraction of stored carbon in forest ecosystems, and coarse woody debris (CWD) decay rates may be sensitive to climate warming. We used an elevation gradient in Colorado Rocky Mountain subalpine forest to examine climate and species effects on dead wood biomass, and on CWD decay rate. Using a new radiocarbon approach, we determined that the turnover time of lodgepole pine CWD (340+/-130 years) was roughly half as long in a site with 2.5-3 degrees C warmer air temperature, as that of pine (630+/-400 years) or Engelmann spruce CWD (800+/-960 and 650+/-410 years) in cooler sites. Across all sites and both species, CWD age ranged from 2 to 600 years, and turnover time was 580+/-180 years. Total standing and fallen dead wood biomass ranged from 4.7+/-0.2 to 54+/-1 Mg ha(-1), and from 2.8 to 60% of aboveground live tree biomass. Dead wood biomass increased 75 kg ha(-1) per meter gain in elevation and decreased 13 Mg ha(-1) for every degree C increase in mean air temperature. Differences in biomass and decay rates along the elevation gradient suggest that climate warming will lead to a loss of dead wood carbon from subalpine forest.

Magnetic Pair Creation Attenuation Altitude Constraints in Gamma-Ray Pulsars

NASA Astrophysics Data System (ADS)

Baring, Matthew; Story, Sarah

The Fermi gamma-ray pulsar database now exceeds 150 sources and has defined an important part of Fermi's science legacy, providing rich information for the interpretation of young energetic pulsars and old millisecond pulsars. Among the well established population characteristics is the common occurrence of exponential turnovers in the 1-10 GeV range. These turnovers are too gradual to arise from magnetic pair creation in the strong magnetic fields of pulsar inner magnetospheres, so their energy can be used to provide lower bounds to the typical altitude of GeV band emission. We explore such constraints due to single-photon pair creation transparency at and below the turnover energy. Our updated computations span both domains when general relativistic influences are important and locales where flat spacetime photon propagation is modified by rotational aberration effects. The altitude bounds, typically in the range of 2-5 stellar radii, provide key information on the emission altitude in radio quiet pulsars that do not possess double-peaked pulse profiles. However, the exceptional case of the Crab pulsar provides an altitude bound of around 20% of the light cylinder radius if pair transparency persists out to 350 GeV, the maximum energy detected by MAGIC. This is an impressive new physics-based constraint on the Crab's gamma-ray emission locale.

Fluorophotometric measurement of the buffering action of human tears in vivo.

PubMed

Yamada, M; Kawai, M; Mochizuki, H; Hata, Y; Mashima, Y

1998-10-01

The buffering action of human tears is thought to be important to keep its pH constant. We measured the change in pH in the precorneal tear film in vivo when the acidic solution is challenged, using a fluorophotometric technique. Twelve eyes from 6 healthy subjects were entered in this study. Each subject was pretreated with either one drop of 0.4% oxybuprocaine for once (light anesthesia), three times (deep anesthesia), or none (controls). The measurement was initiated by instilling 20 microl of 0.067 M phosphate buffer at pH 5.5 containing 2 mM bis-carboxyethyl-carboxyfluorescein free acid, a pH sensitive dye, into the subject's eye. The pH was determined by the ratio of fluorescent intensities at two excitation wavelengths (490 and 430 nm). pH recovery time (PHRT) as defined by the time required for pH to reach 95% of pH at equilibrium was used for the marker of tear buffering action. Tear turnover rate was also determined using the fluorescent decay curve at 430 nm, which was independent of pH, but dependent on dye concentration. Immediately after the instillation, the pH value in the tear film was around 6.0-6.5 in all cases. The tear film rapidly became more alkaline, reaching its normal value in 2.3 +/- 0.5 min in untreated eyes. The pretreatment with 0.4% oxybuprocaine retarded the neutralization process. A single regression analysis revealed that the PHRT had a significant negative correlation with the tear turnover rate (r = -0.78). Our results suggest that the neutralization process of tears largely depends on the tear turnover rate. The buffering action of tears in vivo consists of the tear turnover as well as its chemical buffering capacity.

Effect of Pramlintide on Postprandial Glucose Fluxes in Type 1 Diabetes.

PubMed

Hinshaw, Ling; Schiavon, Michele; Dadlani, Vikash; Mallad, Ashwini; Dalla Man, Chiara; Bharucha, Adil; Basu, Rita; Geske, Jennifer R; Carter, Rickey E; Cobelli, Claudio; Basu, Ananda; Kudva, Yogish C

2016-05-01

Early postprandial hyperglycemia and delayed hypoglycemia remain major problems in current management of type 1 diabetes (T1D). Our objective was to investigate the effects of pramlintide, known to suppress glucagon and delay gastric emptying, on postprandial glucose fluxes in T1D. This was a single-center, inpatient, randomized, crossover study. Twelve patients with T1D who completed the study were analyzed. Subjects were studied on two occasions with or without pramlintide. Triple tracer mixed-meal method and oral minimal model were used to estimate postprandial glucose turnover and insulin sensitivity (SI). Integrated liver insulin sensitivity was calculated based on glucose turnover. Plasma glucagon and insulin were measured. Glucose turnover and SI were the main outcome measures. With pramlintide, 2-hour postprandial glucose, insulin, glucagon, glucose turnover, and SI indices showed: plasma glucose excursions were reduced (difference in incremental area under the curve [iAUC], 444.0 mMmin, P = .0003); plasma insulin concentrations were lower (difference in iAUC, 7642.0 pMmin; P = .0099); plasma glucagon excursions were lower (difference in iAUC, 1730.6 pg/mlmin; P = .0147); meal rate of glucose appearance was lower (difference in iAUC: 1196.2 μM/kg fat free mass [FFM]; P = .0316), endogenous glucose production was not different (difference in iAUC: -105.5 μM/kg FFM; P = .5842), rate of glucose disappearance was lower (difference in iAUC: 1494.2 μM/kg FFM; P = .0083). SI and liver insulin sensitivity were not different between study visits (P > .05). Inhibition of glucagon and gastric emptying delaying reduced 2-hour prandial glucose excursions in T1D by delaying meal rate of glucose appearance.

Cell cycle- and chaperone-mediated regulation of H3K56ac incorporation in yeast.

PubMed

Kaplan, Tommy; Liu, Chih Long; Erkmann, Judith A; Holik, John; Grunstein, Michael; Kaufman, Paul D; Friedman, Nir; Rando, Oliver J

2008-11-01

Acetylation of histone H3 lysine 56 is a covalent modification best known as a mark of newly replicated chromatin, but it has also been linked to replication-independent histone replacement. Here, we measured H3K56ac levels at single-nucleosome resolution in asynchronously growing yeast cultures, as well as in yeast proceeding synchronously through the cell cycle. We developed a quantitative model of H3K56ac kinetics, which shows that H3K56ac is largely explained by the genomic replication timing and the turnover rate of each nucleosome, suggesting that cell cycle profiles of H3K56ac should reveal most first-time nucleosome incorporation events. However, since the deacetylases Hst3/4 prevent use of H3K56ac as a marker for histone deposition during M phase, we also directly measured M phase histone replacement rates. We report a global decrease in turnover rates during M phase and a further specific decrease in turnover at several early origins of replication, which switch from rapidly replaced in G1 phase to stably bound during M phase. Finally, by measuring H3 replacement in yeast deleted for the H3K56 acetyltransferase Rtt109 and its two co-chaperones Asf1 and Vps75, we find evidence that Rtt109 and Asf1 preferentially enhance histone replacement at rapidly replaced nucleosomes, whereas Vps75 appears to inhibit histone turnover at those loci. These results provide a broad perspective on histone replacement/incorporation throughout the cell cycle and suggest that H3K56 acetylation provides a positive-feedback loop by which replacement of a nucleosome enhances subsequent replacement at the same location.

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

[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.

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.

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.

Work hours and turnover intention among hospital physicians in Taiwan: does income matter?

PubMed

Tsai, Yu-Hsuan; Huang, Nicole; Chien, Li-Yin; Chiang, Jen-Huai; Chiou, Shu-Ti

2016-11-21

Physician shortage has become an urgent and critical challenge to many countries. According to the workforce dynamic model, long work hours may be one major pressure point to the attrition of physicians. Financial incentive is a common tool to human power retention. Therefore, this large-scale physician study investigated how pay satisfaction may influence the relationship between work hours and hospital physician's turnover intention. Data were obtained from a nationwide survey of full-time hospital staff members working at 100 hospitals in Taiwan. The analysis sample comprised 2423 full-time physicians. Dependent variable was degree of the physicians' turnover intention to leave the current hospital. The pay satisfaction was assessed by physicians themselves. We employed ordinal logistic regression models to analyze the association between the number of work hours and turnover intention. To consider the cluster effect of hospitals, we used the "gllamm" command in the statistical software package Stata Version 12.1. The results show that 351 (14.5%) of surveyed physicians reported strong intention to leave current hospital. The average work hours per week among hospital physicians was 59.8 h. As expected, work hours exhibited an independent relationship with turnover intention. More importantly, pay satisfaction could not effectively moderate the positive relationship between work hours and intentions to leave current hospital. The findings show that overtime work is prevalent among hospital physicians in Taiwan. Both the Taiwanese government and hospitals must take action to address the emerging problem of physician high turnover rate. Furthermore, hospitals should not consider relying solely on financial incentives to solve the problem. This study encouraged tackling work hour problem, which would lead to the possibility of solving high turnover intention among hospital physicians in Taiwan.

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

[Thermoresistance in Saccharomyces cerevisiae yeasts].

PubMed

Kaliuzhin, V A

2011-01-01

Under natural conditions, yeast Saccharomyces cerevisiae reproduce, as a rule, on the surface of solid or liquid medium. Thus, life cycle of yeast populations is substantially influenced by diurnal changes in ambient temperature. The pattern in the response of unrestricted yeast S. cerevisiae culture to changes in the temperature of cultivation is revealed experimentally. Yeast population, in the absence of environmental constraints on the functioning of cell chemosmotic bioenergetic system, demonstrates the ability of thermoresistance when the temperature of cultivation switches from the range of 12-36 degrees C to 37.5-40 degrees C. During the transient period that is associated with the temperature switching and lasts from 1 to 4 turnover cycles, yeast reproduction rate remains 1.5-2 times higher than under stationary conditions. This is due to evolutionary acquired adaptive activity of cell chemosmotic system. After the adaptive resources exhausting, yeast thermoresistance fully recovers at the temperature range of 12-36 degrees C within one generation time under conditions of both restricted and unrestricted nourishment. Adaptive significance of such thermoresistance seems obvious enough--it allows maintaining high reproduction rate in yeast when ambient temperature is reaching a brief maximum shortly after noon.

Seasonal variation in natural abundance of 2H and 18O in urine samples from rural Nigeria.

PubMed

Harbison, Justin E; Dugas, Lara R; Brieger, William; Tayo, Bamidele O; Alabi, Tunrayo; Schoeller, Dale A; Luke, Amy

2015-07-01

The doubly labeled water (DLW) method is used to measure free-living energy expenditure in humans. Inherent to this technique is the assumption that natural abundances of stable isotopes (2)H and (18)O in body water remain constant over the course of the measurement period and after elimination of the loading dose of DLW will return to the same predose level. To determine variability in the natural abundances of (2)H and (18)O in humans living in a region with seasonal shifts in rain patterns and sources of drinking water, over the course of 12 mo we collected weekly urine samples from four individuals living in southwest Nigeria as well as samples of their drinking water. From ongoing regional studies of hypertension, obesity, and energy expenditure, we estimated average water turnover rate, urine volumes, and sodium and potassium excretion. Results suggest that (2)H and (18)O in urine, mean concentrations of urinary sodium and potassium, urine volume, and total body turnover differed significantly from dry to rainy season. Additionally, seasonal weather variables (mean monthly maximum temperatures, total monthly rainfall, and minimum relative humidity) were all significantly associated with natural abundances in urine. No seasonal difference was observed in drinking water samples. Findings suggest that natural abundances in urine may not remain constant as assumed, and studies incorporating DLW measurements across the transition of seasons should interpret results with caution unless appropriate doses of the tracers are used. Copyright © 2015 the American Physiological Society.

Carbon use efficiency (CUE) and biomass turnover of soil microbial communities as affected by bedrock, land management and soil temperature and moisture

NASA Astrophysics Data System (ADS)

Zheng, Qing; Hu, Yuntao; Richter, Andreas; Wanek, Wolfgang

2017-04-01

Soil microbial carbon use efficiency (CUE), defined as the proportion of organic C taken up that is allocated to microbial growth, represents an important synthetic representation of microbial community C metabolism that describes the flux partitioning between microbial respiration and growth. Therefore, studying microbial CUE is critical for the understanding of soil C cycling. Microbial CUE is thought to vary with environmental conditions (e.g. temperature and soil moisture). Microbial CUE is thought to decrease with increasing temperature and declining soil moisture, as the latter may trigger stress responses (e.g. the synthesis of stress metabolites), which may consequently lower microbial community CUE. However, these effects on microbial CUE have not been adequately measured so far due to methodological restrictions. The most widely used methods for microbial CUE estimation are based on tracing 13C-labeled substrates into microbial biomass and respiratory CO2, approaches that are known to overestimate microbial CUE of native organic matter in soil. Recently, a novel substrate-independent approach based on the measurement of (i) respiration rates and (ii) the incorporation rates of 18O from labelled water into newly formed microbial DNA has been developed in our laboratory for measuring microbial CUE. This approach overcomes the shortcomings of previously used methods and has already been shown to yield realistic estimations of soil microbial CUE. This approach can also be applied to concurrently measure microbial biomass turnover rates, which also influence the sequestration of soil organic C. Microbial turnover rates are also thought to be impacted by environmental factors, but rarely have been directly measured so far. Here, we aimed at determining the short-term effects of environmental factors (soil temperature and soil moisture) on microbial CUE and microbial biomass turnover rates based on the novel 18O approach. Soils from three land-use types (arable fields, pasture and forest) sampled from two geologies (silicate versus limestone) in the same region in Austria were incubated at three temperatures (5, 15 and 25 ˚ C) for 1 day and at three moisture levels (30, 60, 90% water-holding capacity) for 7 days in the laboratory, respectively. We will present the results and discuss major effects of environmental factors as well as of land management and geology on microbial growth, respiration, microbial CUE and microbial biomass turnover, and set those in relation to microbial community composition.

Nitrogen turnover of three different agricultural soils determined by 15N triple labelling

NASA Astrophysics Data System (ADS)

Fiedler, Sebastian R.; Kleineidam, Kristina; Strasilla, Nicol; Schlüter, Steffen; Reent Köster, Jan; Well, Reinhard; Müller, Christoph; Wrage-Mönnig, Nicole

2017-04-01

To meet the demand for data to improve existing N turnover models and to evaluate the effect of different soil physical properties on gross nitrogen (N) transformation rates, we investigated two arable soils and a grassland soil after addition of ammonium nitrate (NH4NO3), where either ammonium (NH4+), or nitrate (NO3-), or both pools have been labelled with 15N at 60 atom% excess (triple 15N tracing method). Besides NH4+, NO3- and nitrite (NO2-) contents with their respective 15N enrichment, nitrous oxide (N2O) and dinitrogen (N2) fluxes have been determined. Each soil was adjusted to 60 % of maximum water holding capacity and pre-incubated at 20˚ C for two weeks. After application of the differently labelled N fertilizer, the soils were further incubated at 20˚ C under aerobic conditions in a He-N2-O2 atmosphere (21 % O2, 76 He, 2% N2) to increase the sensitivity of N2 rates via the 15N gas flux method. Over a 2 week period soil N pools were quantified by 2 M KCl extraction (adjusted to pH 7 to prevent nitrite losses) (Stevens and Laughlin, 1995) and N gas fluxes were measured by gas chromatography in combination with IRMS. Here, we present the pool sizes and fluxes as well as the 15N enrichments during the study. Results are discussed in light of the soil differences that were responsible for the difference in gross N dynamics quantified by the 15N tracing model Ntrace (Müller et al., 2007). References Müller, C., T. Rütting, J. Kattge, R.J. Laughlin, and R.J. Stevens, (2007) Estimation of parameters in complex 15N tracing models by Monte Carlo sampling. Soil Biology & Biochemistry. 39(3): p. 715-726. Stevens, R.J. and R.J. Laughlin, (1995) Nitrite transformations during soil extraction with potassium chloride. Soil Science Society of America Journal. 59(3): p. 933-938.

Longevity of clonal plants: why it matters and how to measure it

PubMed Central

de Witte, Lucienne C.; Stöcklin, Jürg

2010-01-01

Background Species' life-history and population dynamics are strongly shaped by the longevity of individuals, but life span is one of the least accessible demographic traits, particularly in clonal plants. Continuous vegetative reproduction of genets enables persistence despite low or no sexual reproduction, affecting genet turnover rates and population stability. Therefore, the longevity of clonal plants is of considerable biological interest, but remains relatively poorly known. Scope Here, we critically review the present knowledge on the longevity of clonal plants and discuss its importance for population persistence. Direct life-span measurements such as growth-ring analysis in woody plants are relatively easy to take, although, for many clonal plants, these methods are not adequate due to the variable growth pattern of ramets and difficult genet identification. Recently, indirect methods have been introduced in which genet size and annual shoot increments are used to estimate genet age. These methods, often based on molecular techniques, allow the investigation of genet size and age structure of whole populations, a crucial issue for understanding their viability and persistence. However, indirect estimates of clonal longevity are impeded because the process of ageing in clonal plants is still poorly understood and because their size and age are not always well correlated. Alternative estimators for genet life span such as somatic mutations have recently been suggested. Conclusions Empirical knowledge on the longevity of clonal species has increased considerably in the last few years. Maximum age estimates are an indicator of population persistence, but are not sufficient to evaluate turnover rates and the ability of long-lived clonal plants to enhance community stability and ecosystem resilience. In order to understand the dynamics of populations it will be necessary to measure genet size and age structure, not only life spans of single individuals, and to use such data for modelling of genet dynamics. PMID:20880935

[Turnover of Non-medical Staff in Outpatient Oncology Practices: Is Building Social Capital a Solution?].

PubMed

Gloede, T D; Ernstmann, N; Baumann, W; Groß, S E; Ansmann, L; Nitzsche, A; Neumann, M; Wirtz, M; Schmitz, S; Schulz-Nieswandt, F; Pfaff, H

2015-11-01

While a lot is known about potential and actual turnover of non-medical hospital staff, only few data exist for the outpatient setting. In addition, little is known about actual instruments which leaders can use to influence staff turnover in physician practices. In the literature, the social capital of an organisation, which means the amount of trust, common values and reciprocal behaviour in the organisation, has been discussed as a possible field of action. In the present study, staff turnover as perceived by outpatient haematologists and oncologists is presented and analysed as to whether social capital is associated with that staff turnover. In conclusion, measures to increase the social capital of a practice are presented. The present study is based on data gathered in a questionnaire-based survey with members of the Professional Organisation of -Office-Based Haematologists and Oncologists (N=551). The social capital of the practice was captured from the haematologists and oncologists using an existing and validated scale. To analyse the impact of the practice's social capital on staff turnover, as perceived by the physicians, bivariate correlations and linear regression analyses were calculated. In total, 152 haematologists and oncologists participated in the study which represents a response rate of 28%. In the regression analyses, social capital appears as a significant and strong predictor of staff turnover (beta=-0.34; p<0.001). Building social capital within the practice may be an important contribution to reducing staff turnover although the underlying study design does not allow for drawing causal conclusions regarding this relationship. To create social capital in their practice, outpatient physicians may apply measures that facilitate social interaction among staff, foster trust and facilitate cooperation. Such measures may already be applied when hiring and training new staff, but also continuously when leading employees and when organising work tasks, e.g., by establishing regular team meetings. © Georg Thieme Verlag KG Stuttgart · New York.

Pilot-scale study of efficient vermicomposting of agro-industrial wastes.

PubMed

Kumar, Vaidyanathan Vinoth; Shanmugaprakash, M; Aravind, J; Namasivayam, S Karthick Raja

2012-01-01

Pilot-scale vermicomposting was explored using Eudrilus eugeniae for 90 days with 45 days preliminary decomposition using different agro-industrial wastes as substrates. Spent wash and pressmud were mixed together (referred to as PS) and then combined with cow dung (CD) at five different ratios of PS:CD, namely, 25:75 (T1), 50:50 (T2), 75:25 (T3), 85:15 (T4) and 100 (T5), with two replicates for each treatment. All vermibeds expressed a significant decrease in pH (11.4-14.8%), organic carbon (4.2-30.5%) and an increase in total nitrogen (6-29%), AP (5-29%), exchangeable potash (6-21%) and turnover rate (52-66%). Maximum mortality (18.10%) of worms was recorded in T5 treatment. A high manurial value and a matured product was achieved in T3 treatment. The data reveal that pressmud mixed with spent wash can be decomposed through vermicomposting and can help to enhance the quality of vermicompost.

Understanding nurse anesthetists' intention to leave their job: how burnout and job satisfaction mediate the impact of personality and workplace characteristics.

PubMed

Meeusen, Vera C H; Van Dam, Karen; Brown-Mahoney, Chris; Van Zundert, Andre A J; Knape, Hans T A

2011-01-01

The retention of nurse anesthetists is of paramount importance, particularly in view of the fact that the health care workforce is shrinking. Although many health care providers find their work satisfying, they often consider leaving their jobs because of the stress. Are there ways to improve this situation? This study investigated how work environment characteristics and personality dimensions relate to burnout and job satisfaction and ultimately to turnover intention among Dutch nurse anesthetists. An online self-reporting questionnaire survey was performed among Dutch nurse anesthetists. The questionnaire included scales to assess personality dimensions, work climate, work context factors, burnout, job satisfaction, and turnover intention. The research model stated that personality dimensions, work climate, and work context factors, mediated by burnout and job satisfaction, predict turnover intention. Structural equation modeling was used to test the research model. Nine hundred twenty-three questionnaires were completed (46% response rate). Burnout mediated the relationship between personality dimensions and turnover intention; job satisfaction mediated the relationship of work climate and work context factors to turnover intention. To retain nursing staff and to maintain adequate staff strength, it is important to improve job satisfaction by creating a positive work climate and work context and to prevent burnout by selecting the most suitable employees through personality assessment.

Actin Turnover-Mediated Gravity Response in Maize Root Apices

PubMed Central

Mancuso, Stefano; Barlow, Peter W; Volkmann, Dieter

2006-01-01

The dynamic actin cytoskeleton has been proposed to be linked to gravity sensing in plants but the mechanistic understanding of these processes remains unknown. We have performed detailed pharmacological analyses of the role of the dynamic actin cytoskeleton in gravibending of maize (Zea mays) root apices. Depolymerization of actin filaments with two drugs having different mode of their actions, cytochalasin D and latrunculin B, stimulated root gravibending. By contrast, drug-induced stimulation of actin polymerization and inhibition of actin turnover, using two different agents phalloidin and jasplakinolide, compromised the root gravibending. Importantly, all these actin drugs inhibited root growth to similar extents suggesting that high actin turnover is essential for the gravity-related growth responses rather than for the general growth process. Both latrunculin B and cytochalasin D treatments inhibited root growth but restored gravibending of the decapped root apices, indicating that there is a strong potential for effective actin-mediated gravity sensing outside the cap. This elusive gravity sensing outside the root cap is dependent not only on the high rate of actin turnover but also on weakening of myosin activities, as general inhibition of myosin ATPases induced stimulation of gravibending of the decapped root apices. Collectively, these data provide evidence for the actin turnover-mediated gravity sensing outside the root cap. PMID:19521476

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.

Protein turnover, nitrogen balance and rehabilitation.

PubMed

Fern, E B; Waterlow, J C

1983-01-01

Not many studies have been done on protein turnover during recovery from malnutrition. Some relevant information can, however, be obtained from measurements on normal growing animals, since rehabilitation and normal growth have in common a rapid rate of net protein synthesis. The key question is the extent to which net gain in protein results from an increase in synthesis or a decrease in breakdown or both. Different studies have used different methods, and all methods for measuring protein turnover have some disadvantages and sources of error. It is important to bear this in mind in evaluating the results. Consequently, part of this paper will be devoted to questions of methodology. Whole body protein turnover has been measured in children recovering from severe malnutrition. During the phase of rapid catch-up growth the rate of protein synthesis is increased. As might be expected, it increases linearly with the rate of weight gain. At the same time there is a smaller increase in the rate of protein breakdown. The resultant of these two processes is that, over and above the basal rate of protein synthesis, 1.4 grams of protein have to be synthesized for 1 gram to be laid down. Very similar results have been obtained in rapidly growing young pigs. Experimental studies on muscle growth in general confirm the conclusion that, at least in muscle, rapid growth is associated with rapid rates of protein breakdown as well as of synthesis. This has been shown in muscles of young growing rats, as well as in muscles in which hypertrophy has been induced by stretch or other stimuli. In contrast, the evidence suggests that rapid growth involves a fall in the rate of protein degradation. The magnitude of the nitrogen balance under any conditions is determined by the difference between synthesis and breakdown. In the absence of any storage of amino acids, this must be the same as the difference between intake and excretion (S - B = I - E). A question of great interest is whether, at a given intake, the extent of N balance is determined primarily by regulation of synthesis and breakdown or by regulation of amino acid oxidation. Clearly, a reduction in amino acid degradation is equivalent to an increase in amino acid intake. An interesting subject for future research is the extent to which the amino acid degrading enzymes adapt to the requirements imposed by growth and rehabilitation.

Long-term soil transplant simulating climate change with latitude significantly alters microbial temporal turnover.

PubMed

Liang, Yuting; Jiang, Yuji; Wang, Feng; Wen, Chongqing; Deng, Ye; Xue, Kai; Qin, Yujia; Yang, Yunfeng; Wu, Liyou; Zhou, Jizhong; Sun, Bo

2015-12-01

To understand soil microbial community stability and temporal turnover in response to climate change, a long-term soil transplant experiment was conducted in three agricultural experiment stations over large transects from a warm temperate zone (Fengqiu station in central China) to a subtropical zone (Yingtan station in southern China) and a cold temperate zone (Hailun station in northern China). Annual soil samples were collected from these three stations from 2005 to 2011, and microbial communities were analyzed by sequencing microbial 16S ribosomal RNA gene amplicons using Illumina MiSeq technology. Our results revealed a distinctly differential pattern of microbial communities in both northward and southward transplantations, along with an increase in microbial richness with climate cooling and a corresponding decrease with climate warming. The microbial succession rate was estimated by the slope (w value) of linear regression of a log-transformed microbial community similarity with time (time-decay relationship). Compared with the low turnover rate of microbial communities in situ (w=0.046, P<0.001), the succession rate at the community level was significantly higher in the northward transplant (w=0.058, P<0.001) and highest in the southward transplant (w=0.094, P<0.001). Climate warming lead to a faster succession rate of microbial communities as well as lower species richness and compositional changes compared with in situ and climate cooling, which may be related to the high metabolic rates and intense competition under higher temperature. This study provides new insights into the impacts of climate change on the fundamental temporal scaling of soil microbial communities and microbial phylogenetic biodiversity.

Supplement to the History of United States Army Engineer District Far East 1976 to 1977

DTIC Science & Technology

1979-03-01

printing plant equipment . Turnover to the using agency occurred in July 1977. The facility provides printing and publication for the U.S. forces in Korea...negotiation procedures, (b) EUSA engineer troops would erect the buildings while contrac- tors would do sewage treatment plants and overhead...a maximum of 48 men. 14 • 14. FED MFR , 20 January 1977, Subject: FY77 Relocatable Barracks Design; USAEDFE Slide Presentation, 30 June 1976, Subject

Metalimnetic oxygen minima alter the vertical profiles of carbon dioxide and methane in a managed freshwater reservoir.

PubMed

McClure, Ryan P; Hamre, Kathleen D; Niederlehner, B R; Munger, Zackary W; Chen, Shengyang; Lofton, Mary E; Schreiber, Madeline E; Carey, Cayelan C

2018-04-30

Metalimnetic oxygen minimum zones (MOMs) commonly develop during the summer stratified period in freshwater reservoirs because of both natural processes and water quality management. While several previous studies have examined the causes of MOMs, much less is known about their effects, especially on reservoir biogeochemistry. MOMs create distinct redox gradients in the water column which may alter the magnitude and vertical distribution of dissolved methane (CH 4 ) and carbon dioxide (CO 2 ). The vertical distribution and diffusive efflux of CH 4 and CO 2 was monitored for two consecutive open-water seasons in a eutrophic reservoir that develops MOMs as a result of the operation of water quality engineering systems. During both summers, elevated concentrations of CH 4 accumulated within the anoxic MOM, reaching a maximum of 120 μM, and elevated concentrations of CO 2 accumulated in the oxic hypolimnion, reaching a maximum of 780 μM. Interestingly, the largest observed diffusive CH 4 effluxes occurred before fall turnover in both years, while peak diffusive CO 2 effluxes occurred both before and during turnover. Our data indicate that MOMs can substantially change the vertical distribution of CH 4 and CO 2 in the water column in reservoirs, resulting in the accumulation of CH 4 in the metalimnion (vs. at the sediments) and CO 2 in the hypolimnion. Copyright © 2018 Elsevier B.V. All rights reserved.

A new magnetofossil approach to trace paleoenvironmental changes across the Paleocene-Eocene Thermal Maximum

NASA Astrophysics Data System (ADS)

Chang, L.; Harrison, R. J.; Heslop, D.; Roberts, A. P.

2017-12-01

We present a novel multiscale approach to environmental magnetic analysis of geological samples, where combined use of direct nanoscale observations of magnetic mineral particles, rock magnetism and micromagnetic simulation enable production of robust magnetic proxies for tracing important paleoenvironmental change. We have applied such an analysis to the Paleocene-Eocene Thermal Maximum (PETM; 56 Ma), which was the most pronounced Cenozoic global warming event that has been cited as the best analog for understanding present-day warming. Investigating environmental changes across the PETM and associated biological turnovers in marine environments are crucially important because the ocean is a major reservoir for absorbed atmospheric CO2. Nevertheless, knowledge of marine productivity and deep sea oxygenation across the PETM is controversial. We present a new high-resolution PETM record from the South Atlantic Ocean using exceptionally preserved magnetofossils - the inorganic magnetite crystals produced by magnetotactic bacteria. Using rock magnetic properties, statistical analysis of magnetofossil morphologies, and micromagnetic simulation, we demonstrate consistent microfossil signatures for tracing paleoenvironmental changes across the PETM. Our data suggest a transient productivity rise in the pelagic South Atlantic Ocean. The bottom oxygenation decreased gradually from the PETM onset to its peak, and remained low during the early recovery stage of the PETM. Our microbial records provide new insights into the origin and environmental turnovers across the PETM.

Why managers should care about fairness: the effects of aggregate justice perceptions on organizational outcomes.

PubMed

Simons, Tony; Roberson, Quinetta

2003-06-01

This work examines the aggregation of justice perceptions to the departmental level and the business-unit level, the impact of these aggregate perceptions on business-unit-level outcomes, and the usefulness of the distinction between procedural and interpersonal justice at different levels of analysis. Latent variables analyses of individual-level and department-level data from 4,539 employees in 783 departments at 97 hotel properties showed that the 2 justice types exercise unique paths of impact on employees' organizational commitment and thus on turnover intentions and discretionary service behavior. Business-unit-level analyses further demonstrate paths of association between aggregate justice perceptions, aggregate commitment levels, and the business-unit-level outcomes of employee turnover rates and customer satisfaction ratings.

Marketing Management Elements

NASA Astrophysics Data System (ADS)

Costoiu, M.; Ioana, A.; Semenescu, A.; Marcu, D.

2016-11-01

The article takes as a starting point several complementary definitions of marketing. Also present several key points related to marketing policy: defining the position that the company will occupy on the market with respect to competition, fixing the image with what will approach the market, achieving a balance between turnover rates profit and expenses as a condition for the survival of the company. In below article it is proposed an original concept of marketing management. This concept takes into consideration on the one hand correlations between company position in the market definition and on the other hand the image received by customers. The ultimate goal of this original concept of marketing management is to ensure an effective balance between: the turnover rate of profit and expenses of the company.

Stretch-induced prostaglandins and protein turnover in cultured skeletal muscle

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.; Hatfaludy, Sophia; Sohar, Istvan; Shansky, Janet

1990-01-01

The purpose of the study is to determine whether mechanical stimulation of cultured muscle cells influences prostaglandin efflux rates and whether they are related to stretch-induced alterations in protein turnover rates. The materials and methods of the experiment, including cell cultures, mechanical stimulation, protein synthesis, and degradation assays are outlined, and emphasis is placed on the effect of short-term mechanical stimulation in basal medium prostaglandin efflux from cultured skeletal muscle and stretch-induced alterations in prostaglandins efflux in complete medium. The major finding of the study is that mechanical stimulation of tissue-cultured skeletal-muscle cells under conditions inducing skeletal-muscle hypertropy increases the efflux of PGE(2) and PGE(2-alpha) but not 6-keto-PGF(1-alpha), the prostacyclin product.

Seasonal variability in the persistence of dissolved environmental DNA (eDNA) in a marine system: The role of microbial nutrient limitation.

PubMed

Salter, Ian

2018-01-01

Environmental DNA (eDNA) can be defined as the DNA pool recovered from an environmental sample that includes both extracellular and intracellular DNA. There has been a significant increase in the number of recent studies that have demonstrated the possibility to detect macroorganisms using eDNA. Despite the enormous potential of eDNA to serve as a biomonitoring and conservation tool in aquatic systems, there remain some important limitations concerning its application. One significant factor is the variable persistence of eDNA over natural environmental gradients, which imposes a critical constraint on the temporal and spatial scales of species detection. In the present study, a radiotracer bioassay approach was used to quantify the kinetic parameters of dissolved eDNA (d-eDNA), a component of extracellular DNA, over an annual cycle in the coastal Northwest Mediterranean. Significant seasonal variability in the biological uptake and turnover of d-eDNA was observed, the latter ranging from several hours to over one month. Maximum uptake rates of d-eDNA occurred in summer during a period of intense phosphate limitation (turnover <5 hrs). Corresponding increases in bacterial production and uptake of adenosine triphosphate (ATP) demonstrated the microbial utilization of d-eDNA as an organic phosphorus substrate. Higher temperatures during summer may amplify this effect through a general enhancement of microbial metabolism. A partial least squares regression (PLSR) model was able to reproduce the seasonal cycle in d-eDNA persistence and explained 60% of the variance in the observations. Rapid phosphate turnover and low concentrations of bioavailable phosphate, both indicative of phosphate limitation, were the most important parameters in the model. Abiotic factors such as pH, salinity and oxygen exerted minimal influence. The present study demonstrates significant seasonal variability in the persistence of d-eDNA in a natural marine environment that can be linked to the metabolic response of microbial communities to nutrient limitation. Future studies should consider the effect of natural environmental gradients on the seasonal persistence of eDNA, which will be of particular relevance for time-series biomonitoring programs.

Seasonal variability in the persistence of dissolved environmental DNA (eDNA) in a marine system: The role of microbial nutrient limitation

PubMed Central

2018-01-01

Environmental DNA (eDNA) can be defined as the DNA pool recovered from an environmental sample that includes both extracellular and intracellular DNA. There has been a significant increase in the number of recent studies that have demonstrated the possibility to detect macroorganisms using eDNA. Despite the enormous potential of eDNA to serve as a biomonitoring and conservation tool in aquatic systems, there remain some important limitations concerning its application. One significant factor is the variable persistence of eDNA over natural environmental gradients, which imposes a critical constraint on the temporal and spatial scales of species detection. In the present study, a radiotracer bioassay approach was used to quantify the kinetic parameters of dissolved eDNA (d-eDNA), a component of extracellular DNA, over an annual cycle in the coastal Northwest Mediterranean. Significant seasonal variability in the biological uptake and turnover of d-eDNA was observed, the latter ranging from several hours to over one month. Maximum uptake rates of d-eDNA occurred in summer during a period of intense phosphate limitation (turnover <5 hrs). Corresponding increases in bacterial production and uptake of adenosine triphosphate (ATP) demonstrated the microbial utilization of d-eDNA as an organic phosphorus substrate. Higher temperatures during summer may amplify this effect through a general enhancement of microbial metabolism. A partial least squares regression (PLSR) model was able to reproduce the seasonal cycle in d-eDNA persistence and explained 60% of the variance in the observations. Rapid phosphate turnover and low concentrations of bioavailable phosphate, both indicative of phosphate limitation, were the most important parameters in the model. Abiotic factors such as pH, salinity and oxygen exerted minimal influence. The present study demonstrates significant seasonal variability in the persistence of d-eDNA in a natural marine environment that can be linked to the metabolic response of microbial communities to nutrient limitation. Future studies should consider the effect of natural environmental gradients on the seasonal persistence of eDNA, which will be of particular relevance for time-series biomonitoring programs. PMID:29474423

Assembly and Turnover of Short Actin Filaments by the Formin INF2 and Profilin*

PubMed Central

Gurel, Pinar S.; A, Mu; Guo, Bingqian; Shu, Rui; Mierke, Dale F.; Higgs, Henry N.

2015-01-01

INF2 (inverted formin 2) is a formin protein with unique biochemical effects on actin. In addition to the common formin ability to accelerate actin nucleation and elongation, INF2 can also sever filaments and accelerate their depolymerization. Although we understand key attributes of INF2-mediated severing, we do not understand the mechanism by which INF2 accelerates depolymerization subsequent to severing. Here, we show that INF2 can create short filaments (<60 nm) that continuously turn over actin subunits through a combination of barbed end elongation, severing, and WH2 motif-mediated depolymerization. This pseudo-steady state condition occurs whether starting from actin filaments or monomers. The rate-limiting step of the cycle is nucleotide exchange of ADP for ATP on actin monomers after release from the INF2/actin complex. Profilin addition has two effects: 1) to accelerate filament turnover 6-fold by accelerating nucleotide exchange and 2) to shift the equilibrium toward polymerization, resulting in longer filaments. In sum, our findings show that the combination of multiple interactions of INF2 with actin can work in concert to increase the ATP turnover rate of actin. Depending on the ratio of INF2:actin, this increased flux can result in rapid filament depolymerization or maintenance of short filaments. We also show that high concentrations of cytochalasin D accelerate ATP turnover by actin but through a different mechanism from that of INF2. PMID:26124273

Uniform distributions of glucose oxidation and oxygen extraction in gray matter of normal human brain: No evidence of regional differences of aerobic glycolysis.

PubMed

Hyder, Fahmeed; Herman, Peter; Bailey, Christopher J; Møller, Arne; Globinsky, Ronen; Fulbright, Robert K; Rothman, Douglas L; Gjedde, Albert

2016-05-01

Regionally variable rates of aerobic glycolysis in brain networks identified by resting-state functional magnetic resonance imaging (R-fMRI) imply regionally variable adenosine triphosphate (ATP) regeneration. When regional glucose utilization is not matched to oxygen delivery, affected regions have correspondingly variable rates of ATP and lactate production. We tested the extent to which aerobic glycolysis and oxidative phosphorylation power R-fMRI networks by measuring quantitative differences between the oxygen to glucose index (OGI) and the oxygen extraction fraction (OEF) as measured by positron emission tomography (PET) in normal human brain (resting awake, eyes closed). Regionally uniform and correlated OEF and OGI estimates prevailed, with network values that matched the gray matter means, regardless of size, location, and origin. The spatial agreement between oxygen delivery (OEF≈0.4) and glucose oxidation (OGI ≈ 5.3) suggests that no specific regions have preferentially high aerobic glycolysis and low oxidative phosphorylation rates, with globally optimal maximum ATP turnover rates (VATP ≈ 9.4 µmol/g/min), in good agreement with (31)P and (13)C magnetic resonance spectroscopy measurements. These results imply that the intrinsic network activity in healthy human brain powers the entire gray matter with ubiquitously high rates of glucose oxidation. Reports of departures from normal brain-wide homogeny of oxygen extraction fraction and oxygen to glucose index may be due to normalization artefacts from relative PET measurements. © The Author(s) 2016.

Patterns of nitrogen accumulation and cycling in riparian floodplain ecosystems along the Green and Yampa rivers

USGS Publications Warehouse

Carol E., Adair; Binkley, Dan; Andersen, Douglas C.

2004-01-01

Patterns of nitrogen (N) accumulation and turnover in riparian systems in semi-arid regions are poorly understood, particularly in those ecosystems that lack substantial inputs from nitrogen fixing vegetation. We investigated sources and fluxes of N in chronosequences of riparian forests along the regulated Green River and the free-flowing Yampa River in semi-arid northwestern Colorado. Both rivers lack significant inputs from N-fixing vegetation. Total soil nitrogen increased through time along both rivers, at a rate of about 7.8 g N m−2 year−1 for years 10–70, and 2.7 g N m−2year−1 from years 70–170. We found that the concentration of N in freshly deposited sediments could account for most of the soil N that accumulated in these floodplain soils. Available N (measured by ion exchange resin bags) increased with age along both rivers, more than doubling in 150 years. In contrast to the similar levels of total soil N along these rivers, N turnover rates, annual N mineralization, net nitrification rates, resin-N, and foliar N were all 2–4 times higher along the Green River than the Yampa River. N mineralization and net nitrification rates generally increased through time to steady or slightly declining rates along the Yampa River. Along the Green River, rates of mineralization and nitrification were highest in the youngest age class. The high levels of available N and N turnover in young sites are not characteristic of riparian chronosequences and could be related to changes in hydrology or plant community composition associated with the regulation of the Green River.

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

Jazrawi, R.P.; Ferraris, R.; Bridges, C.

The apparent fractional turnover rate of the gamma-labeled bile acid analogue 75-selenohomocholic acid-taurine (75-SeHCAT) was assessed from decline in radioactivity over the gallbladder area on 4 successive days using a gamma-camera, and was compared in the same subjects with the fractional turnover rate of the corresponding natural bile acid, cholic acid-taurine, labeled with 14C ((14C)CAT) using the classical Lindstedt technique. Very similar results were obtained in 5 healthy individuals (coefficient of variation 4.8%, medians 0.35 and 0.34, respectively). By contrast, the fractional deconjugation rate assessed from zonal scanning of glycine- and taurine-conjugated bile acids on thin-layer chromatography was much lessmore » for 75-SeHCAT than for (14C)CAT (0.02 and 0.13, respectively; p less than 0.05). The fractional rate for deconjugation plus dehydroxylation was also determined by zonal scanning, and gave lower values for 75-SeHCAT than for (14C)CAT (0.02 and 0.12, respectively; p less than 0.05). There was a striking similarity between the fractional rate for deconjugation alone and that for deconjugation plus dehydroxylation for both bile acids in individual samples (r = 0.999, p less than 0.001), suggesting that these two processes might occur simultaneously and probably involve the same bacteria. We conclude that our scintiscanning technique provides an accurate, noninvasive method of measuring fractional turnover rate of a bile acid in humans, and that the finding that 75SeHCAT remains conjugated with taurine during enterohepatic recycling means that absorption should be specific for the ileal active transport site, thus rendering it an ideal substance for assessing ileal function.« less

Structural empowerment and anticipated turnover among behavioural health nurses.

PubMed

Smith, Thomas; Capitulo, Kathleen Leask; Quinn Griffin, Mary T; Fitzpatrick, Joyce J

2012-07-01

The aim of this pilot study was to examine the relationship between structural empowerment and anticipated turnover among behavioural health nurses. There have been several studies relating structural empowerment to a range of organizational characteristics and personal attributes of nurses themselves. There are also previous studies linking the key variables in the present study, but no previous research of behavioural health nurses was available. A quantitative design was used for this cross-sectional pilot study. All registered nurses (RN) working on inpatient units in the study facility were invited to participate (n = 97). An anonymous survey was sent to all potential participants. The response rate was 53% (n = 50). The majority of participants perceived themselves as moderately empowered. There was a significant negative correlation between empowerment and anticipated turnover. The results of this pilot study among behavioural health nurses are similar to the results among nurses working in other clinical areas. Nurse managers should be cognizant of the factors that enhance nurses' perceptions of empowerment, particularly related to issues of retention and anticipated turnover among behavioural health nurses. © 2012 Blackwell Publishing 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.

Effect of alcohol consumption on whole-body protein turnover in healthy adults.

PubMed

Wutzke, Klaus D; Krentz, Helga; Bruns, Gerrit

2011-03-01

The aim of the study was to investigate the whole-body protein turnover, either before or after continuous, moderate ethanol-induced oxidative stress by red wine consumption over a relatively short period in healthy volunteers. Ten healthy adults received an individual regular diet over 20 days. After 10 days, the subjects consumed 0.4 ml ethanol kg(-1) day(-1) as red wine together with dinner over a 10-day period. After 8 and 18 days, respectively, a (15)N-labelled yeast protein was administered in a dosage of 4.2 mg kg(-1) body weight. Urine and faeces were collected over 48 h, respectively. The (15)N-enrichment was measured by isotope ratio mass spectrometry, whereas the protein flux rates were calculated by a three-compartment model. The whole-body protein turnover without/with red wine consumption amounted to 3.73±0.6 and 3.49±0.6 g kg(-1) day(-1) (not significant), respectively. Moderate alcohol consumption does not induce significant short-term changes in the whole-body protein turnover of healthy adults.

Evolutionary dynamics of plants and animals: a comparative approach

NASA Technical Reports Server (NTRS)

Valentine, J. W.; Tiffney, B. H.; Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

1991-01-01

Patterns of longevity and rate of appearance of taxa in the fossil record indicate a different evolutionary dynamic between land plants and marine invertebrates. Among marine invertebrates, rates of taxonomic turnover declined through the Phanerozoic, with increasingly extinction-resistant, long-lived, clades coming to dominate. Among terrestrial vascular plants, rates of turnover increased through the Phanerozoic, with short-lived, extinction-prone clades coming to dominate from the Devonian to the present. Terrestrial vertebrates appear to approximate the marine invertebrate pattern more closely than the plant record. We identify two features which individually or jointly may have influenced this distinction. First, land plants continuously invaded stressful environments during their evolution, while marine invertebrates and terrestrial vertebrates did not. Second, the relative structural simplicity and indeterminate mode of plant growth vs. the relative structural complexity and determinate mode of animal growth may have influenced the timing of major clade origin in the two groups.

Potentially conflicting metabolic demands of diving and exercise in seals.

PubMed

Castellini, M A; Murphy, B J; Fedak, M; Ronald, K; Gofton, N; Hochachka, P W

1985-02-01

Metabolic replacement rates (Ra) for glucose and free fatty acids (FFA) were determined during rest, exercise, and diving conditions in the gray seal using bolus injections of radiotracers. In the exercise experiments the seal swam at a metabolic rate elevated twofold over resting Ra for glucose and FFA while resting were similar to values found in terrestrial mammals and other marine mammal species. During exercise periods glucose turnover increased slightly while FFA turnover changes were variable. However, the energetic demands of exercise could not be met by the increase in the replacement rates of glucose or FFA even if both were completely oxidized. Under diving conditions the tracer pool displayed radically different specific activity curves indicative of the changes in perfusion and metabolic rate associated with a strong dive response. Since the radiotracer curves during exercise and diving differed qualitatively and quantitatively, it is possible that similar studies on freely diving animals can be used to assess the role of the diving response during underwater swimming in nature.

BOREAS TGB-12 Rn-222 Flux Data over the NSA

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Conrad, Sara K.; Trumbore, Susan; Sundquist, Eric; Winston, Greg

2000-01-01

The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. Sampling strategies for soils were designed to take advantage of local fire chronosequences, so that the accumulation of carbon in new moss growth could be determined. All the data are used to 1) calculate the inventory of carbon and nitrogen in moss and mineral soil layers at NSA sites, 2) determine the rates of input and turnover (using both accumulation since the last stand-killing fire and radiocarbon data), and 3) link changes in soil respiration rate to shifts in the C-14 content of soil CO2 to determine the average "age" respired CO2. These Rn-222 flux data were collected from 15-Nov-1993 to 16-Aug-1994 over the NSA sites. The data in this data set are stored in tabular ASCII files.

Regulation of colonic epithelial cell turnover by IDO contributes to the innate susceptibility of SCID mice to Trichuris muris infection.

PubMed

Bell, L V; Else, K J

2011-04-01

Tryptophan catabolism via the kynurenine pathway is dependent on the enzyme Indoleamine 2,3-dioxygenase (IDO). Expression of IDO is upregulated in a number of inflammatory settings such as wounding and infection, and the resulting local tryptophan depletion may inhibit the replication of intracellular pathogens. Indo gene expression is upregulated in the gut during chronic infection with the mouse whipworm Trichuris muris. We demonstrate an increase in the rate of colonic epithelial cell turnover after inhibition of IDO in T. muris-infected SCID mice, leading to a significant expulsion of parasite burden. We identify the goblet cell as a novel source of IDO and present data revealing a new role for IDO in the regulation of epithelial cell turnover post-infectious challenge. © 2011 Blackwell Publishing Ltd.

Low-Turnover Drug Molecules: A Current Challenge for Drug Metabolism Scientists.

PubMed

Hutzler, J Matthew; Ring, Barbara J; Anderson, Shelby R

2015-12-01

In vitro assays using liver subcellular fractions or suspended hepatocytes for characterizing the metabolism of drug candidates play an integral role in the optimization strategy employed by medicinal chemists. However, conventional in vitro assays have limitations in their ability to predict clearance and generate metabolites for low-turnover (slowly metabolized) drug molecules. Due to a rapid loss in the activity of the drug-metabolizing enzymes, in vitro incubations are typically performed for a maximum of 1 hour with liver microsomes to 4 hours with suspended hepatocytes. Such incubations are insufficient to generate a robust metabolic response for compounds that are slowly metabolized. Thus, the challenge of accurately estimating low human clearance with confidence has emerged to be among the top challenges that drug metabolism scientists are confronted with today. In response, investigators have evaluated novel methodologies to extend incubation times and more sufficiently measure metabolism of low-turnover drugs. These methods include plated human hepatocytes in monoculture, and a novel in vitro methodology using a relay of sequential incubations with suspended cryopreserved hepatocytes. In addition, more complex in vitro cellular models, such as HepatoPac (Hepregen, Medford, MA), a micropatterned hepatocyte-fibroblast coculture system, and the HµREL (Beverley Hills, CA) hepatic coculture system, have been developed and characterized that demonstrate prolonged enzyme activity. In this review, the advantages and disadvantages of each of these in vitro methodologies as it relates to the prediction of clearance and metabolite identification will be described in an effort to provide drug metabolism scientists with the most up-to-date experimental options for dealing with the complex issue of low-turnover drug candidates. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

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.

Hydrocortisone Stimulation of RNA Synthesis in Induction of Hepatic Enzymes

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

Kenney, Francis T.; Wicks, Wesley D.; Greenman, David L.

Increased synthesis of hepatic enzymes due to hydrocortisone is preceded by an increase in the rate of synthesis of nuclear RNA. Pulse-labeled RNA from liver nuclei was fractionated by a differential thermal phenol procedures, and the labeled RNA of each fraction was characterized by sucrose gradient centrifugation and base composition analysis. Hormone treatment increases the rate of synthesis of three types of RNA: (1) the nuclear precursor to ribosomal RNA, (2) a rapid turnover component with base composition similar to the tissue DNA, and (3) transfer RNA. Much of the total isotope incorporation into transfer RNA can be traced tomore » turnover of the terminal adenylate residue, but this type of labeling is insensitive to the hormone. The steroid also stimulates isotope incorporation into tissue precursor pools. The effect is abolished by actinomycin and thus is secondary to the hormonal stimulation of RNA synthesis. Growth hormone stimulates RNA synthesis in both intact and adrenalectomized rats, but induces the rapid turnover enzymes (tyrosine transaminase and tryptophan pyrrolase) only in the presence of functional adrenals. It therefore seems that glucocorticoids initiate both a generalized increase in synthesis of RNA and a selective induction of specific enzymes.« less

Strengthening communication to overcome lateral violence.

PubMed

Ceravolo, Diane J; Schwartz, Diane G; Foltz-Ramos, Kelly M; Castner, Jessica

2012-07-01

This quality improvement project aims to reduce nurse-to-nurse lateral violence and create a more respectful workplace culture through a series of workshops. Lateral violence is common and pervasive in nursing, with detrimental physical, psychological and organizational consequences. This project describes the organization-wide pre- and post-intervention survey of registered nurses' perception of lateral violence and turnover. After the workshop series, nurses who reported experiencing verbal abuse fell from 90 to 76%. A greater percentage of nurses perceived a workplace that was respectful to others and in which it was safe to express opinions. After the workshop series, a greater percentage of nurses felt determined to solve the problem after an incident of lateral violence, while a smaller percentage felt powerless. Nursing turnover and vacancy rates dropped. Educational workshops that enhanced awareness of lateral violence and improved assertive communication resulted in a better working environment, reduction in turnover and vacancy rates, and reduced incidence of lateral violence. Nurse managers must raise awareness of lateral violence with individual and organizational consequences. Nursing leadership can effect organizational change to lesson lateral violence and enhance a healthy workplace culture by replicating our intervention or components of our workshops. © 2012 Blackwell Publishing Ltd.

24 CFR 246.8 - Materials to be submitted to HUD in support of preemption request.

Code of Federal Regulations, 2011 CFR

2011-04-01

... separate breakdown of rent loss due to tenant turnover for the past 2 years. (6) A certified statement... by the following: (i) Tax rates or appraisals, (ii) Utility rates, (iii) Contracts for employees or... appraisals, (ii) Utility rates, (iii) Contracts for employees or services, (iv) Insurance. If there are none...

BOREAS TGB-12 Rn-222 Activity Data over the NSA

NASA Technical Reports Server (NTRS)

Trumbore, Susan; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Sundquist, Eric; Winston, Greg

2000-01-01

The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. Sampling strategies for soils were designed to take advantage of local fire chronosequences, so that the accumulation of carbon in regrowing mosses could be determined. All the data are used to: (1) calculate the inventory of carbon and nitrogen in moss and mineral soil layers at NSA sites, (2) determine the rates of input and turnover (using both accumulation since the last stand-killing fire and radiocarbon data), and (3) link changes in soil respiration rate to shifts in the C-14 content of soil CO2 to determine the average "age" respired CO2 . These Rn-222 activity data were collected from 15-Nov-1993 to 16-Aug-1994 over the NSA sites. They are useful for determining the rate of gas exchange between soil and the overlying atmosphere. The data in this data set are stored in tabular ASCII files.

An ecological analysis of prison overcrowding and suicide rates in England and Wales, 2000-2014.

PubMed

van Ginneken, Esther F J C; Sutherland, Alex; Molleman, Toon

Prisoners are at a greatly increased risk of suicides compared to the general population. Differences in suicide risk can be partly explained by individual risk factors, but the contribution of prison characteristics remains unclear. Overcrowded prisons have higher suicide rates, but this may be related to prison function, security level, population size and turnover. The aim of the current study was to investigate the contribution of each of these prison characteristics to suicide rates, using data from the Ministry of Justice for adult prisons in England and Wales from 2000 to 2014. Negative binomial regression analysis showed that larger population size, higher turnover, higher security and public management were associated with higher suicide rates. When controlling for these factors, overcrowding was not found to be related to suicide rates. Questions remain about the causal mechanisms underlying variation in prison suicides and the impact of the lived experience of overcrowding. Further research is needed to examine the relative contribution of prison and prisoner characteristics to suicides. Copyright © 2016 Elsevier Ltd. All rights reserved.

Glycemic Control and Bone Turnover in Older Mexican Americans with Type 2 Diabetes

PubMed Central

Smith, Scott M.; Lee, MinJae; Pervin, Hannah; Musgrave, Paul; Watt, Gordon P.; Nader, Shahla; Khosla, Sundeep; Ambrose, Catherine G.; McCormick, Joseph B.; Fisher-Hoch, Susan P.

2018-01-01

Altered bone quality, caused by underlying metabolic changes of type 2 diabetes (T2D), has been hypothesized to cause altered bone strength and turnover leading to increased fracture risk in T2D patients. Current understanding about changes in bone turnover markers in T2D patients is mainly based on studies focused on Caucasian men and women. However, Hispanic populations have the highest prevalence of both T2D and osteoporosis in the US. We investigated associations of glycemic control (in terms of glycated hemoglobin [HbA1c]) and bone turnover rate in 69 older (≥50 years) Mexican American Cameron County Hispanic Cohort (CCHC) participants with T2D. Multivariable analyses were conducted to assess the associations between HbA1c (%), serum osteocalcin (OC), and serum sclerostin. In agreement with published reports from other racial/ethnic populations, our study found that lower bone turnover (indicated by lower serum OC) occurred in Mexican American men with T2D who had poorer glycemic control. For the women in our study, we found no significant association between glycemic control and OC. In contrast, HbA1c was positively associated with sclerostin for women, with near significance (p = 0.07), while no association was found in men. We recommend screening Mexican American individuals with T2D, specifically those with poor glycemic control, for bone loss and fracture risk. PMID:29862008

Remote video auditing with real-time feedback in an academic surgical suite improves safety and efficiency metrics: a cluster randomised study.

PubMed

Overdyk, Frank J; Dowling, Oonagh; Newman, Sheldon; Glatt, David; Chester, Michelle; Armellino, Donna; Cole, Brandon; Landis, Gregg S; Schoenfeld, David; DiCapua, John F

2016-12-01

Compliance with the surgical safety checklist during operative procedures has been shown to reduce inhospital mortality and complications but proper execution by the surgical team remains elusive. We evaluated the impact of remote video auditing with real-time provider feedback on checklist compliance during sign-in, time-out and sign-out and case turnover times. Prospective, cluster randomised study in a 23-operating room (OR) suite. Surgeons, anaesthesia providers, nurses and support staff. ORs were randomised to receive, or not receive, real-time feedback on safety checklist compliance and efficiency metrics via display boards and text messages, followed by a period during which all ORs received feedback. Checklist compliance (Pass/Fail) during sign-in, time-out and sign-out demonstrated by (1) use of checklist, (2) team attentiveness, (3) required duration, (4) proper sequence and duration of case turnover times. Sign-in, time-out and sign-out PASS rates increased from 25%, 16% and 32% during baseline phase (n=1886) to 64%, 84% and 68% for feedback ORs versus 40%, 77% and 51% for no-feedback ORs (p<0.004) during the intervention phase (n=2693). Pass rates were 91%, 95% and 84% during the all-feedback phase (n=2001). For scheduled cases (n=1406, 71%), feedback reduced mean turnover times by 14% (41.4 min vs 48.1 min, p<0.004), and the improvement was sustained during the all-feedback period. Feedback had no effect on turnover time for unscheduled cases (n=587, 29%). Our data indicate that remote video auditing with feedback improves surgical safety checklist compliance for all cases, and turnover time for scheduled cases, but not for unscheduled cases. 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/.

Remote video auditing with real-time feedback in an academic surgical suite improves safety and efficiency metrics: a cluster randomised study

PubMed Central

Overdyk, Frank J; Dowling, Oonagh; Newman, Sheldon; Glatt, David; Chester, Michelle; Armellino, Donna; Cole, Brandon; Landis, Gregg S; Schoenfeld, David; DiCapua, John F

2016-01-01

Importance Compliance with the surgical safety checklist during operative procedures has been shown to reduce inhospital mortality and complications but proper execution by the surgical team remains elusive. Objective We evaluated the impact of remote video auditing with real-time provider feedback on checklist compliance during sign-in, time-out and sign-out and case turnover times. Design, setting Prospective, cluster randomised study in a 23-operating room (OR) suite. Participants Surgeons, anaesthesia providers, nurses and support staff. Exposure ORs were randomised to receive, or not receive, real-time feedback on safety checklist compliance and efficiency metrics via display boards and text messages, followed by a period during which all ORs received feedback. Main outcome(s) and measure(s) Checklist compliance (Pass/Fail) during sign-in, time-out and sign-out demonstrated by (1) use of checklist, (2) team attentiveness, (3) required duration, (4) proper sequence and duration of case turnover times. Results Sign-in, time-out and sign-out PASS rates increased from 25%, 16% and 32% during baseline phase (n=1886) to 64%, 84% and 68% for feedback ORs versus 40%, 77% and 51% for no-feedback ORs (p<0.004) during the intervention phase (n=2693). Pass rates were 91%, 95% and 84% during the all-feedback phase (n=2001). For scheduled cases (n=1406, 71%), feedback reduced mean turnover times by 14% (41.4 min vs 48.1 min, p<0.004), and the improvement was sustained during the all-feedback period. Feedback had no effect on turnover time for unscheduled cases (n=587, 29%). Conclusions and relevance Our data indicate that remote video auditing with feedback improves surgical safety checklist compliance for all cases, and turnover time for scheduled cases, but not for unscheduled cases. PMID:26658775

Sunlight-Dependent Hydrogen Production by Photosensitizer/Hydrogenase Systems.

PubMed

Adam, David; Bösche, Lisa; Castañeda-Losada, Leonardo; Winkler, Martin; Apfel, Ulf-Peter; Happe, Thomas

2017-03-09

We report a sustainable in vitro system for enzyme-based photohydrogen production. The [FeFe]-hydrogenase HydA1 from Chlamydomonas reinhardtii was tested for photohydrogen production as a proton-reducing catalyst in combination with eight different photosensitizers. Using the organic dye 5-carboxyeosin as a photosensitizer and plant-type ferredoxin PetF as an electron mediator, HydA1 achieves the highest light-driven turnover number (TON HydA1 ) yet reported for an enzyme-based in vitro system (2.9×10 6  mol(H 2 ) mol(cat) -1 ) and a maximum turnover frequency (TOF HydA1 ) of 550 mol(H 2 ) mol(HydA1) -1  s -1 . The system is fueled very effectively by ambient daylight and can be further simplified by using 5-carboxyeosin and HydA1 as a two-component photosensitizer/biocatalyst system without an additional redox mediator. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adrenocortical Gap Junctions and Their Functions

PubMed Central

Bell, Cheryl L.; Murray, Sandra A.

2016-01-01

Adrenal cortical steroidogenesis and proliferation are thought to be modulated by gap junction-mediated direct cell–cell communication of regulatory molecules between cells. Such communication is regulated by the number of gap junction channels between contacting cells, the rate at which information flows between these channels, and the rate of channel turnover. Knowledge of the factors regulating gap junction-mediated communication and the turnover process are critical to an understanding of adrenal cortical cell functions, including development, hormonal response to adrenocorticotropin, and neoplastic dedifferentiation. Here, we review what is known about gap junctions in the adrenal gland, with particular attention to their role in adrenocortical cell steroidogenesis and proliferation. Information and insight gained from electrophysiological, molecular biological, and imaging (immunocytochemical, freeze fracture, transmission electron microscopic, and live cell) techniques will be provided. PMID:27445985

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.

Assessing honeybee and wasp thermoregulation and energetics—New insights by combination of flow-through respirometry with infrared thermography

PubMed Central

Stabentheiner, Anton; Kovac, Helmut; Hetz, Stefan K.; Käfer, Helmut; Stabentheiner, Gabriel

2012-01-01

Endothermic insects like honeybees and some wasps have to cope with an enormous heat loss during foraging because of their small body size in comparison to endotherms like mammals and birds. The enormous costs of thermoregulation call for optimisation. Honeybees and wasps differ in their critical thermal maximum, which enables the bees to kill the wasps by heat. We here demonstrate the benefits of a combined use of body temperature measurement with infrared thermography, and respiratory measurements of energy turnover (O2 consumption or CO2 production via flow-through respirometry) to answer questions of insect ecophysiological research, and we describe calibrations to receive accurate results. To assess the question of what foraging honeybees optimise, their body temperature was compared with their energy turnover. Honeybees foraging from an artificial flower with unlimited sucrose flow increased body surface temperature and energy turnover with profitability of foraging (sucrose content of the food; 0.5 or 1.5 mol/L). Costs of thermoregulation, however, were rather independent of ambient temperature (13–30 °C). External heat gain by solar radiation was used to increase body temperature. This optimised foraging energetics by increasing suction speed. In determinations of insect respiratory critical thermal limits, the combined use of respiratory measurements and thermography made possible a more conclusive interpretation of respiratory traces. PMID:22723718

Continuous hair cell turnover in the inner ear vestibular organs of a mammal, the Daubenton's bat (Myotis daubentonii).

PubMed

Kirkegaard, M; Jørgensen, J M

2000-02-01

In both humans and mice the number of hair cells in the inner ear sensory epithelia declines with age, indicating cell death (Park et al. 1987; Rosenhall 1973). However, recent reports demonstrate the ability of the vestibular sensory epithelia to regenerate after injury (Forge et al. 1993, 1998; Kuntz and Oesterle 1998; Li and Forge 1997; Rubel et al. 1995; Tanyeri et al. 1995). Still, a continuous hair cell turnover in the vestibular epithelia has not previously been demonstrated in mature mammals. Bats are the only flying mammals, and they are known to live to a higher age than animals of equal size. The maximum age of many species is 20 years, with average lifespans of 4-6 years (Schober and Grimmberger 1989). Further, the young are fully developed and able to fly at the age of 2 months, and thus the vestibular organs are thought to be differentiated at that age. Consequently, long-lived mammals such as bats might compensate for the loss of hair cells by producing new hair cells in their postembryonic life. Here we show that the utricular macula of adult Daubenton's bats (more than 6 months old) contains innervated immature hair cells as well as apoptotic hair cells, which strongly indicates a continuous turnover of hair cells, as previously demonstrated in birds.

Continuous Hair Cell Turnover in the Inner Ear Vestibular Organs of a Mammal, the Daubenton's Bat (Myotis daubentonii)

NASA Astrophysics Data System (ADS)

Kirkegaard, M.; Jørgensen, J. M.

In both humans and mice the number of hair cells in the inner ear sensory epithelia declines with age, indicating cell death (Park et al. 1987; Rosenhall 1973). However, recent reports demonstrate the ability of the vestibular sensory epithelia to regenerate after injury (Forge et al. 1993, 1998; Kuntz and Oesterle 1998; Li and Forge 1997; Rubel et al. 1995; Tanyeri et al. 1995). Still, a continuous hair cell turnover in the vestibular epithelia has not previously been demonstrated in mature mammals. Bats are the only flying mammals, and they are known to live to a higher age than animals of equal size. The maximum age of many species is 20years, with average lifespans of 4-6years (Schober and Grimmberger 1989). Further, the young are fully developed and able to fly at the age of 2months, and thus the vestibular organs are thought to be differentiated at that age. Consequently, long-lived mammals such as bats might compensate for the loss of hair cells by producing new hair cells in their postembryonic life. Here we show that the utricular macula of adult Daubenton's bats (more than 6months old) contains innervated immature hair cells as well as apoptotic hair cells, which strongly indicates a continuous turnover of hair cells, as previously demonstrated in birds.

School Improvement Grants in Georgia: A Quantitative Analysis of the Relationship between the College and Career Ready Performance Index, Students' Proficiency, and Graduation Rates

ERIC Educational Resources Information Center

Covington, Char-Shenda D.

2016-01-01

There are a myriad of factors that contribute to the lowest performing schools in Georgia that School Improvement Grants (SIGs) are designed to ameliorate. Declining graduation rates, dwindling student achievement, high teacher turnover rates, and students leaving high school at an alarming rate ill-prepared for college and/or the workforce…

Identification of ribozymes within a ribozyme library that efficiently cleave a long substrate RNA.

PubMed Central

Campbell, T B; Cech, T R

1995-01-01

Positions 2-6 of the substrate-binding internal guide sequence (IGS) of the L-21 Sca I form of the Tetrahymena thermophila intron were mutagenized to produce a GN5 IGS library. Ribozymes within the GN5 library capable of efficient cleavage of an 818-nt human immunodeficiency virus type 1 vif-vpr RNA, at 37 degrees C, were identified by ribozyme-catalyzed guanosine addition to the 3' cleavage product. Three ribozymes (IGS = GGGGCU, GGCUCC, and GUGGCU) within the GN5 library that actively cleaved the long substrate were characterized kinetically and compared to the wild-type ribozyme (GGAGGG) and two control ribozymes (GGAGUC and GGAGAU). The two control ribozymes have specific sites within the long substrate, but were not identified during screening of the library. Under single-turnover conditions, ribozymes GGGGCU, GGCUCC, and GUGGCU cleaved the 818-nt substrate 4- to 200-fold faster than control ribozymes. Short cognate substrates, which should be structureless and therefore accessible to ribozyme binding, were cleaved at similar rates by all ribozymes except GGGGCU, which showed a fourfold rate enhancement. The rate of cleavage of long relative to short substrate under single-turnover conditions suggests that GGCUCC and GUGGCU were identified because of accessibility to their specific cleavage sites within the long substrate (substrate-specific effects), whereas GGGGCU was identified because of an enhanced rate of substrate binding despite a less accessible site in the long substrate. Even though screening was performed with 100-fold excess substrate (relative to total ribozyme), the rate of multiple-turnover catalysis did not contribute to identification of trans-cleaving ribozymes in the GN5 library. PMID:7489519

Long-term soil transplant simulating climate change with latitude significantly alters microbial temporal turnover

PubMed Central

Liang, Yuting; Jiang, Yuji; Wang, Feng; Wen, Chongqing; Deng, Ye; Xue, Kai; Qin, Yujia; Yang, Yunfeng; Wu, Liyou; Zhou, Jizhong; Sun, Bo

2015-01-01

To understand soil microbial community stability and temporal turnover in response to climate change, a long-term soil transplant experiment was conducted in three agricultural experiment stations over large transects from a warm temperate zone (Fengqiu station in central China) to a subtropical zone (Yingtan station in southern China) and a cold temperate zone (Hailun station in northern China). Annual soil samples were collected from these three stations from 2005 to 2011, and microbial communities were analyzed by sequencing microbial 16S ribosomal RNA gene amplicons using Illumina MiSeq technology. Our results revealed a distinctly differential pattern of microbial communities in both northward and southward transplantations, along with an increase in microbial richness with climate cooling and a corresponding decrease with climate warming. The microbial succession rate was estimated by the slope (w value) of linear regression of a log-transformed microbial community similarity with time (time–decay relationship). Compared with the low turnover rate of microbial communities in situ (w=0.046, P<0.001), the succession rate at the community level was significantly higher in the northward transplant (w=0.058, P<0.001) and highest in the southward transplant (w=0.094, P<0.001). Climate warming lead to a faster succession rate of microbial communities as well as lower species richness and compositional changes compared with in situ and climate cooling, which may be related to the high metabolic rates and intense competition under higher temperature. This study provides new insights into the impacts of climate change on the fundamental temporal scaling of soil microbial communities and microbial phylogenetic biodiversity. PMID:25989371

Growth factor involvement in tension-induced skeletal muscle growth

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.

1993-01-01

Long-term manned space travel will require a better understanding of skeletal muscle atrophy which results from microgravity. Astronaut strength and dexterity must be maintained for normal mission operations and for emergency situations. Although exercise in space slows the rate of muscle loss, it does not prevent it. A biochemical understanding of how gravity/tension/exercise help to maintain muscle size by altering protein synthesis and/or degradation rate should ultimately allow pharmacological intervention to prevent muscle atrophy in microgravity. The overall objective is to examine some of the basic biochemical processes involved in tension-induced muscle growth. With an experimental in vitro system, the role of exogenous and endogenous muscle growth factors in mechanically stimulated muscle growth are examined. Differentiated avian skeletal myofibers can be 'exercised' in tissue culture using a newly developed dynamic mechanical cell stimulator device which simulates different muscle activity patterns. Patterns of mechanical activity which significantly affect muscle growth and metabolic characteristics were found. Both exogenous and endogenous growth factors are essential for tension-induced muscle growth. Exogenous growth factors found in serum, such as insulin, insulin-like growth factors, and steroids, are important regulators of muscle protein turnover rates and mechanically-induced muscle growth. Endogenous growth factors are synthesized and released into the culture medium when muscle cells are mechanically stimulated. At least one family of mechanically induced endogenous factors, the prostaglandins, help to regulate the rates of protein turnover in muscle cells. Endogenously synthesized IGF-1 is another. The interaction of muscle mechanical activity and these growth factors in the regulation of muscle protein turnover rates with our in vitro model system is studied.

Teachers' Perceptions of Factors that Contribute to Attrition

ERIC Educational Resources Information Center

Johnson, Daisy M.

2010-01-01

Major stakeholders in education are focused on the high rate of teachers leaving the profession. The review of literature indicated the number of teachers leaving the profession outnumbered the number of teachers entering or staying in the profession. High teacher turnover rates weaken schools' abilities to build and sustain professional teacher…

Labor Market Turnover and Joblessness for Hispanic American Youth.

ERIC Educational Resources Information Center

Stephenson, Stanley P., Jr.

Using data from the National Longitudinal Survey of Youth's continuous work history files, this paper examines how individual and market characteristics influence the unemployment rates of Hispanic youth. The results show that family income, marital status, post-school vocational education, age, and local unemployment rates significantly influence…

HiFiVS Modeling of Flow Diverter Deployment Enables Hemodynamic Characterization of Complex Intracranial Aneurysm Cases

PubMed Central

Xiang, Jianping; Damiano, Robert J.; Lin, Ning; Snyder, Kenneth V.; Siddiqui, Adnan H.; Levy, Elad I.; Meng, Hui

2016-01-01

Object Flow diversion via Pipeline Embolization Device (PED) represents the most recent advancement in endovascular therapy of intracranial aneurysms. This exploratory study aims at a proof of concept for an advanced device-modeling tool in conjunction with computational fluid dynamics (CFD) to evaluate flow modification effects by PED in real treatment cases. Methods We performed computational modeling of three PED-treated complex aneurysm cases. Case I had a fusiform vertebral aneurysm treated with a single PED. Case II had a giant internal carotid artery (ICA) aneurysm treated with 2 PEDs. Case III consisted of two tandem ICA aneurysms (a and b) treated by a single PED. Our recently developed high fidelity virtual stenting (HiFiVS) technique was used to recapitulate the clinical deployment process of PEDs in silico for these three cases. Pre- and post-treatment aneurysmal hemodynamics using CFD simulation was analyzed. Changes in aneurysmal flow velocity, inflow rate, and wall shear stress (WSS) (quantifying flow reduction) and turnover time (quantifying stasis) were calculated and compared with clinical outcome. Results In Case I (occluded within the first 3 months), the aneurysm experienced the most drastic aneurysmal flow reduction after PED placement, where the aneurysmal average velocity, inflow rate and average WSS was decreased by 76.3%, 82.5% and 74.0%, respectively, while the turnover time was increased to 572.1% of its pre-treatment value. In Case II (occluded at 6 months), aneurysmal average velocity, inflow rate and average WSS were decreased by 39.4%, 38.6%, and 59.1%, respectively, and turnover time increased to 163.0%. In Case III, Aneurysm III-a (occluded at 6 months) experienced decrease by 38.0%, 28.4%, and 50.9% in aneurysmal average velocity, inflow rate and average WSS, respectively and increase to 139.6% in turnover time, which was quite similar to Aneurysm II. Surprisingly, the adjacent Aneurysm III-b experienced more substantial flow reduction (decrease by 77.7%, 53.0%, and 84.4% in average velocity, inflow rate and average WSS, respectively, and increase to 213.0% in turnover time) than Aneurysm III-a, which qualitatively agreed with angiographic observation at 3-month follow-up. However, Aneurysm III-b remained patent at both 6 months and 9 months. A closer examination of the vascular anatomy of Case III revealed blood draining to the ophthalmic artery off Aneurysm III-b, which may have prevented its complete thrombosis. Conclusion This proof-of-concept study demonstrates that HiFiVE modeling of flow diverter deployment enables detailed characterization of hemodynamic alteration by PED placement. Post-treatment aneurysmal flow reduction may be correlated with aneurysm occlusion outcome. However, predicting aneurysm treatment outcome by flow diverters also requires consideration of other factors including vascular anatomy. PMID:26090829

Selection of ribozymes that catalyse multiple-turnover Diels–Alder cycloadditions by using in vitro compartmentalization

PubMed Central

Agresti, Jeremy J.; Kelly, Bernard T.; Jäschke, Andres; Griffiths, Andrew D.

2005-01-01

In vitro compartmentalization (IVC) has previously been used to evolve protein enzymes. Here, we demonstrate how IVC can be applied to select RNA enzymes (ribozymes) for a property that has previously been unselectable: true intermolecular catalysis. Libraries containing 1011 ribozyme genes are compartmentalized in the aqueous droplets of a water-in-oil emulsion, such that most droplets contain no more than one gene, and transcribed in situ. By coencapsulating the gene, RNA, and the substrates/products of the catalyzed reaction, ribozymes can be selected for all enzymatic properties: substrate recognition, product formation, rate acceleration, and turnover. Here we exploit the complementarity of IVC with systematic evolution of ligands by exponential enrichment (SELEX), which allows selection of larger libraries (≥1015) and for very small rate accelerations (kcat/kuncat) but only selects for intramolecular single-turnover reactions. We selected ≈1014 random RNAs for Diels–Alderase activity with five rounds of SELEX, then six to nine rounds with IVC. All selected ribozymes catalyzed the Diels–Alder reaction in a truly bimolecular fashion and with multiple turnover. Nearly all ribozymes selected by using eleven rounds of SELEX alone contain a common catalytic motif. Selecting with SELEX then IVC gave ribozymes with significant sequence variations in this catalytic motif and ribozymes with completely novel motifs. Interestingly, the catalytic properties of all of the selected ribozymes were quite similar. The ribozymes are strongly product inhibited, consistent with the Diels–Alder transition state closely resembling the product. More efficient Diels–Alderases may need to catalyze a second reaction that transforms the product and prevents product inhibition. PMID:16260754

A Western diet induced NAFLD in LDLR(-/)(-) mice is associated with reduced hepatic glutathione synthesis.

PubMed

Li, Ling; Zhang, Guo-Fang; Lee, Kwangwon; Lopez, Rocio; Previs, Stephen F; Willard, Belinda; McCullough, Arthur; Kasumov, Takhar

2016-07-01

Oxidative stress plays a key role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Glutathione is the major anti-oxidant involved in cellular oxidative defense, however there are currently no simple non-invasive methods for assessing hepatic glutathione metabolism in patients with NAFLD. As a primary source of plasma glutathione, liver plays an important role in interorgan glutathione homeostasis. In this study, we have tested the hypothesis that measurements of plasma glutathione turnover could be used to assess the hepatic glutathione metabolism in LDLR(-/)(-) mice, a mouse model of diet-induced NAFLD. Mice were fed a standard low fat diet (LFD) or a high fat diet containing cholesterol (a Western type diet (WD)). The kinetics of hepatic and plasma glutathione were quantified using the (2)H2O metabolic labeling approach. Our results show that a WD leads to reduced fractional synthesis rates (FSR) of hepatic (25%/h in LFD vs. 18%/h in WD, P<0.05) and plasma glutathione (43%/h in LFD vs. 21%/h in WD, P<0.05), without any significant effect on their absolute production rates (PRs). WD-induced concordant changes in both hepatic and plasma glutathione turnover suggest that the plasma glutathione turnover measurements could be used to assess hepatic glutathione metabolism. The safety, simplicity, and low cost of the (2)H2O-based glutathione turnover approach suggest that this method has the potential for non-invasive probing of hepatic glutathione metabolism in patients with NAFLD and other diseases. Copyright © 2016 Elsevier Inc. All rights reserved.

A Western diet induced NAFLD in LDLR−/− mice is associated with reduced hepatic glutathione synthesis

PubMed Central

Li, Ling; Zhang, Guo-Fang; Lee, Kwangwon; Lopez, Rocio; Previs, Stephen F.; Willard, Belinda; McCullough, Arthur; Kasumov, Takhar

2017-01-01

Oxidative stress plays a key role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Glutathione is the major anti-oxidant involved in cellular oxidative defense, however there are currently no simple non-invasive methods for assessing hepatic glutathione metabolism in patients with NAFLD. As a primary source of plasma glutathione, liver plays an important role in interorgan glutathione homeostasis. In this study, we have tested the hypothesis that measurements of plasma glutathione turnover could be used to assess the hepatic glutathione metabolism in LDLR−/− mice, a mouse model of diet-induced NAFLD. Mice were fed a standard low fat diet (LFD) or a high fat diet containing cholesterol (a Western type diet (WD)). The kinetics of hepatic and plasma glutathione were quantified using the 2H2O metabolic labeling approach. Our results show that a WD leads to reduced fractional synthesis rates (FSR) of hepatic (25%/h in LFD vs. 18%/h in WD, P < 0.05) and plasma glutathione (43%/h in LFD vs. 21%/h in WD, P <0.05), without any significant effect on their absolute production rates (PRs). WD-induced concordant changes in both hepatic and plasma glutathione turnover suggest that the plasma glutathione turnover measurements could be used to assess hepatic glutathione metabolism. The safety, simplicity, and low cost of the 2H2O-based glutathione turnover approach suggest that this method has the potential for non-invasive probing of hepatic glutathione metabolism in patients with NAFLD and other diseases. PMID:27036364

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

Cenedella, R.J.; Fleschner, C.R.

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

Contribution of Interfacility Patient Movement to Overall Methicillin-Resistant Staphylococcus aureus Prevalence Levels

PubMed Central

Barnes, Sean L.; Harris, Anthony D.; Golden, Bruce L.; Wasil, Edward A.; Furuno, Jon P.

2012-01-01

Objectives The effect of patient movement between hospitals and long-term care facilities (LTCFs) on methicillin-resistant Staphylococcus aureus (MRSA) prevalence levels is unknown. We investigated these effects to identify scenarios that may lead to increased prevalence in either facility type. Methods We used a hybrid simulation model to simulate MRSA transmission among hospitals and LTCFs. Transmission within each facility was determined by mathematical model equations. The model predicted the long-term prevalence of each facility and was used to assess the effects of facility size, patient turnover, and decolonization. Results Analyses of various healthcare networks suggest that the effect of patients moving from a LTCF to a hospital is negligible unless the patients are consistently admitted to the same unit. In such cases, MRSA prevalence can increase significantly regardless of the endemic level. Hospitals can cause sustained increases in prevalence when transferring patients to LTCFs, where the population size is smaller and patient turnover is less frequent. For 1 particular scenario, the steady-state prevalence of a LTCF increased from 6.9% to 9.4% to 13.8% when the transmission rate of the hospital increased from a low to a high transmission rate. Conclusions These results suggest that the relative facility size and the patient discharge rate are 2 key factors that can lead to sustained increases in MRSA prevalence. Consequently, small facilities or those with low turnover rates are especially susceptible to sustaining increased prevalence levels, and they become more so when receiving patients from larger, high-prevalence facilities. Decolonization is an infection-control strategy that can mitigate these effects. PMID:22011533

Evidence for a central 5-hydroxytryptamine receptor stimulation by lysergic acid diethylamide

PubMed Central

Andén, N.-E.; Corrodi, H.; Fuxe, K.; Hökfelt, T.

1968-01-01

1. Lysergic acid diethylamide (LSD) and the 5-hydroxytryptamine (5-HT) precursor, 5-hydroxytryptophan produced similar functional effects in rat spinal cord and brain to the 5-hydroxytryptamine precursor 5-hydroxytryptophan, which indicates that LSD stimulates central 5-HT receptors. 2. By means of combined histochemical and biochemical techniques it was found that LSD reduced the turnover rate of brain and spinal cord 5-HT, studied after inhibition of the tryptophan hydroxylase by α-propyldopacetamide. The turnover of brain noradrenaline but not dopamine was somewhat accelerated. 3. The functional and chemical effects by LSD were related to dose and to time. They were not observed after the LSD analogues 2-bromo-LSD and methylsergide. 4. The retardation of the 5-HT turnover by LSD may be due to negative feed-back mechanisms evoked by direct stimulation of the central 5-HT receptors. ImagesFIG. 1FIG. 2 PMID:5302837

Osteocalcin and bone-specific alkaline phosphatase in Asian elephants (Elephas maximus) at different ages.

PubMed

Arya, Nlin; Moonarmart, Walasinee; Cheewamongkolnimit, Nareerat; Keratikul, Nutcha; Poon-Iam, Sawinee; Routh, Andrew; Bumpenpol, Pitikarn; Angkawanish, Taweepoke

2015-11-01

Bone turnover markers could offer a potential alternative means for the early diagnosis of metabolic bone disease in young growing elephants although the baseline of bone turnover markers in elephant is not well established. The aim of this study was to determine any relationship between the age of captive Asian elephants (Elephas maximus) and markers of bone formation. Serum samples from 24 female Asian elephants were collected to evaluate levels of two bone formation markers, namely, osteocalcin (OC) and bone-specific alkaline phosphatase (BAP). Both intact and N-terminal midfragment OC and BAP were negatively correlated with age. The findings demonstrate that younger elephants have a higher rate of bone turnover than older elephants. Use of these and additional bone markers could lead to the establishment of validated protocols for the monitoring of bone disease in elephants. Copyright © 2015 Elsevier Ltd. All rights reserved.