Measuring and modeling the lifetime of nitrous oxide including its variability

DOE PAGES

Prather, Michael J.; Hsu, Juno; DeLuca, Nicole M.; ...

2015-05-14

The lifetime of nitrous oxide, the third-most-important human-emitted greenhouse gas, is based to date primarily on model studies or scaling to other gases. This work calculates a semiempirical lifetime based on Microwave Limb Sounder satellite measurements of stratospheric profiles of nitrous oxide, ozone, and temperature; laboratory cross-section data for ozone and molecular oxygen plus kinetics for O( 1D); the observed solar spectrum; and a simple radiative transfer model. The result is 116 ± 9 years. The observed monthly-to-biennial variations in lifetime and tropical abundance are well matched by four independent chemistry-transport models driven by reanalysis meteorological fields for the periodmore » of observation (2005–2010), but all these models overestimate the lifetime due to lower abundances in the critical loss region near 32 km in the tropics. These models plus a chemistry-climate model agree on the nitrous oxide feedback factor on its own lifetime of 0.94 ± 0.01, giving N 2O perturbations an effective residence time of 109 years. Combining this new empirical lifetime with model estimates of residence time and preindustrial lifetime (123 years) adjusts our best estimates of the human-natural balance of emissions today and improves the accuracy of projected nitrous oxide increases over this century.« less

A practical model of thin disk regenerative amplifier based on analytical expression of ASE lifetime

NASA Astrophysics Data System (ADS)

Zhou, Huang; Chyla, Michal; Nagisetty, Siva Sankar; Chen, Liyuan; Endo, Akira; Smrz, Martin; Mocek, Tomas

2017-12-01

In this paper, a practical model of a thin disk regenerative amplifier has been developed based on an analytical approach, in which Drew A. Copeland [1] had evaluated the loss rate of the upper state laser level due to ASE and derived the analytical expression of the effective life-time of the upper-state laser level by taking the Lorentzian stimulated emission line-shape and total internal reflection into account. By adopting the analytical expression of effective life-time in the rate equations, we have developed a less numerically intensive model for predicting and analyzing the performance of a thin disk regenerative amplifier. Thanks to the model, optimized combination of various parameters can be obtained to avoid saturation, period-doubling bifurcation or first pulse suppression prior to experiments. The effective life-time due to ASE is also analyzed against various parameters. The simulated results fit well with experimental data. By fitting more experimental results with numerical model, we can improve the parameters of the model, such as reflective factor which is used to determine the weight of boundary reflection within the influence of ASE. This practical model will be used to explore the scaling limits imposed by ASE of the thin disk regenerative amplifier being developed in HiLASE Centre.

Profit-Based Model Selection for Customer Retention Using Individual Customer Lifetime Values.

PubMed

Óskarsdóttir, María; Baesens, Bart; Vanthienen, Jan

2018-03-01

The goal of customer retention campaigns, by design, is to add value and enhance the operational efficiency of businesses. For organizations that strive to retain their customers in saturated, and sometimes fast moving, markets such as the telecommunication and banking industries, implementing customer churn prediction models that perform well and in accordance with the business goals is vital. The expected maximum profit (EMP) measure is tailored toward this problem by taking into account the costs and benefits of a retention campaign and estimating its worth for the organization. Unfortunately, the measure assumes fixed and equal customer lifetime value (CLV) for all customers, which has been shown to not correspond well with reality. In this article, we extend the EMP measure to take into account the variability in the lifetime values of customers, thereby basing it on individual characteristics. We demonstrate how to incorporate the heterogeneity of CLVs when CLVs are known, when their prior distribution is known, and when neither is known. By taking into account individual CLVs, our proposed approach of measuring model performance gives novel insights when deciding on a customer retention campaign. The method is dependent on the characteristics of the customer base as is compliant with modern business analytics and accommodates the data-driven culture that has manifested itself within organizations.

Lifetime risk of renal replacement therapy in Europe: a population-based study using data from the ERA-EDTA Registry.

PubMed

van den Brand, Jan A J G; Pippias, Maria; Stel, Vianda S; Caskey, Fergus J; Collart, Frederic; Finne, Partik; Heaf, James; Jais, Jean-Philippe; Kramar, Reinhard; Massy, Ziad A; De Meester, Johan; Traynor, Jamie P; Reisæter, Anna Varberg; Wetzels, Jack F M; Jager, Kitty J

2017-02-01

Upcoming KDIGO guidelines for the evaluation of living kidney donors are expected to move towards a personal risk-based evaluation of potential donors. We present the age and sex-specific lifetime risk of renal replacement therapy (RRT) for end-stage renal disease in 10 European countries. We defined lifetime risk of RRT as the cumulative incidence of RRT up to age 90 years. We obtained RRT incidence rates per million population by 5-year age groups and sex using data from the European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) Registry, and used these to estimate the cumulative incidence of RRT, adjusting for competing mortality risk. Lifetime risk of RRT varied from 0.44% to 2.05% at age 20 years and from 0.17% to 1.59% at age 70 years across countries, and was twice as high in men as in women. Lifetime RRT risk decreased with age, ranging from an average of 0.77% to 0.44% in 20- to- 70-year-old women, and from 1.45% to 0.96% in 20- to- 70-year-old men. The lifetime risk of RRT increased slightly over the past decade, more so in men than in women. However, it appears to have stabilized or even decreased slightly in more recent years. The lifetime risk of RRT decreased with age, was lower in women as compared with men of equal age and varied considerably throughout Europe. Given the substantial differences in lifetime risk of RRT between the USA and Europe, country-specific estimates should be used in the evaluation and communication of the risk of RRT for potential living kidney donors. © The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

Lifetime exposure to arsenic in drinking water and bladder cancer: a population-based case–control study in Michigan, USA

PubMed Central

Slotnick, Melissa J.; AvRuskin, Gillian A.; Schottenfeld, David; Jacquez, Geoffrey M.; Wilson, Mark L.; Goovaerts, Pierre; Franzblau, Alfred; Nriagu, Jerome O.

2014-01-01

Objective Arsenic in drinking water has been linked with the risk of urinary bladder cancer, but the dose–response relationships for arsenic exposures below 100 µg/L remain equivocal. We conducted a population-based case–control study in southeastern Michigan, USA, where approximately 230,000 people were exposed to arsenic concentrations between 10 and 100 µg/L. Methods This study included 411 bladder cancer cases diagnosed between 2000 and 2004, and 566 controls recruited during the same period. Individual lifetime exposure profiles were reconstructed, and residential water source histories, water consumption practices, and water arsenic measurements or modeled estimates were determined at all residences. Arsenic exposure was estimated for 99% of participants’ person-years. Results Overall, an increase in bladder cancer risk was not found for time-weighted average lifetime arsenic exposure >10 µg/L when compared with a reference group exposed to <1 µg/L (odds ratio (OR) = 1.10; 95% confidence interval (CI): 0.65, 1.86). Among ever-smokers, risks from arsenic exposure >10 µg/L were similarly not elevated when compared to the reference group (OR = 0.94; 95% CI: 0.50, 1.78). Conclusions We did not find persuasive evidence of an association between low-level arsenic exposure and bladder cancer. Selecting the appropriate exposure metric needs to be thoughtfully considered when investigating risk from low-level arsenic exposure. PMID:20084543

Spectral hole lifetimes and spin population relaxation dynamics in neodymium-doped yttrium orthosilicate

NASA Astrophysics Data System (ADS)

Cruzeiro, E. Zambrini; Tiranov, A.; Usmani, I.; Laplane, C.; Lavoie, J.; Ferrier, A.; Goldner, P.; Gisin, N.; Afzelius, M.

2017-05-01

We present a detailed study of the lifetime of optical spectral holes due to population storage in Zeeman sublevels of Nd3 +:Y2SiO5 . The lifetime is measured as a function of magnetic field strength and orientation, temperature, and Nd3 + doping concentration. At the lowest temperature of 3 K we find a general trend where the lifetime is short at low field strengths, then increases to a maximum lifetime at a few hundred mT, and then finally decays rapidly for high field strengths. This behavior can be modeled with a relaxation rate dominated by Nd3 +-Nd3 + cross relaxation at low fields and spin lattice relaxation at high magnetic fields. The maximum lifetime depends strongly on both the field strength and orientation, due to the competition between these processes and their different angular dependencies. The cross relaxation limits the maximum lifetime for concentrations as low as 30 ppm of Nd3 + ions. By decreasing the concentration to less than 1 ppm we could completely eliminate the cross relaxation, reaching a lifetime of 3.8 s at 3 K. At higher temperatures the spectral hole lifetime is limited by the magnetic-field-independent Raman and Orbach processes. In addition we show that the cross relaxation rate can be strongly reduced by creating spectrally large holes of the order of the optical inhomogeneous broadening. Our results are important for the development and design of new rare-earth-ion doped crystals for quantum information processing and narrow-band spectral filtering for biological tissue imaging.

The costs of inequality: whole-population modelling study of lifetime inpatient hospital costs in the English National Health Service by level of neighbourhood deprivation

PubMed Central

Doran, Tim; Cookson, Richard

2016-01-01

Background There are substantial socioeconomic inequalities in both life expectancy and healthcare use in England. In this study, we describe how these two sets of inequalities interact by estimating the social gradient in hospital costs across the life course. Methods Hospital episode statistics, population and index of multiple deprivation data were combined at lower-layer super output area level to estimate inpatient hospital costs for 2011/2012 by age, sex and deprivation quintile. Survival curves were estimated for each of the deprivation groups and used to estimate expected annual costs and cumulative lifetime costs. Results A steep social gradient was observed in overall inpatient hospital admissions, with rates ranging from 31 298/100 000 population in the most affluent fifth of areas to 43 385 in the most deprived fifth. This gradient was steeper for emergency than for elective admissions. The total cost associated with this inequality in 2011/2012 was £4.8 billion. A social gradient was also observed in the modelled lifetime costs where the lower life expectancy was not sufficient to outweigh the higher average costs in the more deprived populations. Lifetime costs for women were 14% greater than for men, due to higher costs in the reproductive years and greater life expectancy. Conclusions Socioeconomic inequalities result in increased morbidity and decreased life expectancy. Interventions to reduce inequality and improve health in more deprived neighbourhoods have the potential to save money for health systems not only within years but across peoples’ entire lifetimes, despite increased costs due to longer life expectancies. PMID:27189975

Development and validation of a new population-based simulation model of osteoarthritis in New Zealand.

PubMed

Wilson, R; Abbott, J H

2018-04-01

To describe the construction and preliminary validation of a new population-based microsimulation model developed to analyse the health and economic burden and cost-effectiveness of treatments for knee osteoarthritis (OA) in New Zealand (NZ). We developed the New Zealand Management of Osteoarthritis (NZ-MOA) model, a discrete-time state-transition microsimulation model of the natural history of radiographic knee OA. In this article, we report on the model structure, derivation of input data, validation of baseline model parameters against external data sources, and validation of model outputs by comparison of the predicted population health loss with previous estimates. The NZ-MOA model simulates both the structural progression of radiographic knee OA and the stochastic development of multiple disease symptoms. Input parameters were sourced from NZ population-based data where possible, and from international sources where NZ-specific data were not available. The predicted distributions of structural OA severity and health utility detriments associated with OA were externally validated against other sources of evidence, and uncertainty resulting from key input parameters was quantified. The resulting lifetime and current population health-loss burden was consistent with estimates of previous studies. The new NZ-MOA model provides reliable estimates of the health loss associated with knee OA in the NZ population. The model structure is suitable for analysis of the effects of a range of potential treatments, and will be used in future work to evaluate the cost-effectiveness of recommended interventions within the NZ healthcare system. Copyright © 2018 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Lifetime sexual violence and childbirth expectations - A Norwegian population based cohort study.

PubMed

Henriksen, Lena; Schei, Berit; Lukasse, Mirjam

2016-05-01

this study aimed to explore the association between lifetime sexual violence and expectations about childbirth. Norwegian population-based cohort study. women presenting for routine ultrasound examinations were recruited to the Norwegian Mother and Child Cohort Study between 1999 and 2008. 78,660 pregnant women. sexual violence and expectations about childbirth were self-reported during pregnancy using postal questionnaires. Risk estimations were performed using multivariable logistic regression analysis and stratified by parity. fear of childbirth, the thoughts about pain relief, worries about the infant's health and looking forward to the arrival of the infant. of 78,660 women, 18.4% reported a history of sexual violence and 0.9% were exposed to sexual violence within the last 12 months, including during the current pregnancy. We found that nulliparous women who reported previous or recent sexual violence had a decrease in the odds of looking forward to the arrival of the infant with an AOR of 0.8 (95% CI 0.7-0.9) and 0.4 (95% CI 0.3-0.6), respectively, compared to non-abused women. The same pattern was observed among multiparous women and they were more likely to report worries about the infant's health. Severe sexual violence (rape) was associated with concerns about childbirth, especially for nulliparous women that were more likely to express fear of birth, a hope for a pain-free birth, a desire for caesarean section and worries about the infant's health than non-exposed women. women with a lifetime exposure to sexual violence, both past experiences and within the last 12 months, were less likely to look forward to the arrival of the infant than non-exposed women, and they were more likely to worry about the infant's health. Women with experiences of severe sexual violence (rape) had more concerns about childbirth than women without this experience. This finding shows that exploring women's attitudes toward childbirth may work as an approach when examining

Differentiating quiescent cancer cell populations in heterogeneous samples with fluorescence lifetime imaging

NASA Astrophysics Data System (ADS)

Heaster, Tiffany M.; Walsh, Alex J.; Skala, Melissa C.

2016-03-01

Measurement of relative fluorescence intensities of NAD(P)H and FAD with fluorescence lifetime imaging (FLIM) allows metabolic characterization of cancerous populations and correlation to treatment response. However, quiescent populations of cancer cells introduce heterogeneity to the tumor and exhibit resistance to standard therapies, requiring a better understanding of this influence on treatment outcome. Significant differences were observed between proliferating and quiescent cell populations upon comparison of respective redox ratios (p<0.05) and FAD lifetimes (p<0.05) across monolayers and in mixed samples. These results demonstrate that metabolic activity may function as a marker for separation and characterization of proliferating and quiescent cancer cells within mixed samples, contributing to comprehensive investigation of heterogeneity-dependent drug resistance.

Validity of LIDAS (LIfetime Depression Assessment Self-report): a self-report online assessment of lifetime major depressive disorder.

PubMed

Bot, M; Middeldorp, C M; de Geus, E J C; Lau, H M; Sinke, M; van Nieuwenhuizen, B; Smit, J H; Boomsma, D I; Penninx, B W J H

2017-01-01

There is a paucity of valid, brief instruments for the assessment of lifetime major depressive disorder (MDD) that can be used in, for example, large-scale genomics, imaging or biomarker studies on depression. We developed the LIfetime Depression Assessment Self-report (LIDAS), which assesses lifetime MDD diagnosis according to DSM criteria, and is largely based on the widely used Composite International Diagnostic Interview (CIDI). Here, we tested the feasibility and determined the sensitivity and specificity for measuring lifetime MDD with this new questionnaire, with a regular CIDI as reference. Sensitivity and specificity analyses of the online lifetime MDD questionnaire were performed in adults with (n = 177) and without (n = 87) lifetime MDD according to regular index CIDIs, selected from the Netherlands Study of Depression and Anxiety (NESDA) and Netherlands Twin Register (NTR). Feasibility was tested in an additional non-selective, population-based sample of NTR participants (n = 245). Of the 753 invited persons, 509 (68%) completed the LIDAS, of which 419 (82%) did this online. User-friendliness of the instrument was rated high. Median completion time was 6.2 min. Sensitivity and specificity for lifetime MDD were 85% [95% confidence interval (CI) 80-91%] and 80% (95% CI 72-89%), respectively. This LIDAS instrument gave a lifetime MDD prevalence of 20.8% in the population-based sample. Measuring lifetime MDD with an online instrument was feasible. Sensitivity and specificity were adequate. The instrument gave a prevalence of lifetime MDD in line with reported population prevalences. LIDAS is a promising tool for rapid determination of lifetime MDD status in large samples, such as needed for genomics studies.

Lifetime risk of stroke in young-aged and middle-aged Chinese population: the Chinese Multi-Provincial Cohort Study

PubMed Central

Wang, Ying; Liu, Jing; Wang, Wei; Wang, Miao; Qi, Yue; Xie, Wuxiang; Li, Yan; Sun, Jiayi; Liu, Jun; Zhao, Dong

2016-01-01

Objective: Stroke is a major cause of premature death in China. Early prevention of stroke requires a more effective method to differentiate the stroke risk among young-aged and middle-aged individuals than the 10-year risk of cardiovascular disease. This study aimed to establish a lifetime stroke risk model and risk charts for the young-aged and middle-aged population in China. Methods: The Chinese Multi-Provincial Cohort Study participants (n = 21 953) aged 35–84 years without cardiovascular disease at baseline were followed for 18 years (263 016 person-years). Modified Kaplan–Meier method was used to estimate the mean lifetime stroke risk up to age of 80 years and the lifetime stroke risk according to major stroke risk factors for the population aged 35–60 years. Results: A total of 917 participants developed first-ever strokes. For the participants aged 35–40 years (98 stroke cases), the lifetime stroke risk was 18.0 and 14.7% in men and women, respectively. Blood pressure most effectively discriminated the lifetime stroke risk. The lifetime risk of stroke for the individuals with all risk factors optimal was 8–10 times lower compared with those with two or more high risk factors at age 35–60 years at baseline. Conclusion: In young-aged and middle-aged population, the lifetime stroke risk will keep very low if major risk factors especially blood pressure level is at optimal levels, but the risk substantially increases even with a slight elevation of major risk factors, which could not be identified using 10-year risk estimation. PMID:27512963

Deployment-based lifetime optimization for linear wireless sensor networks considering both retransmission and discrete power control.

PubMed

Li, Ruiying; Ma, Wenting; Huang, Ning; Kang, Rui

2017-01-01

A sophisticated method for node deployment can efficiently reduce the energy consumption of a Wireless Sensor Network (WSN) and prolong the corresponding network lifetime. Pioneers have proposed many node deployment based lifetime optimization methods for WSNs, however, the retransmission mechanism and the discrete power control strategy, which are widely used in practice and have large effect on the network energy consumption, are often neglected and assumed as a continuous one, respectively, in the previous studies. In this paper, both retransmission and discrete power control are considered together, and a more realistic energy-consumption-based network lifetime model for linear WSNs is provided. Using this model, we then propose a generic deployment-based optimization model that maximizes network lifetime under coverage, connectivity and transmission rate success constraints. The more accurate lifetime evaluation conduces to a longer optimal network lifetime in the realistic situation. To illustrate the effectiveness of our method, both one-tiered and two-tiered uniformly and non-uniformly distributed linear WSNs are optimized in our case studies, and the comparisons between our optimal results and those based on relatively inaccurate lifetime evaluation show the advantage of our method when investigating WSN lifetime optimization problems.

Modelling lifetime data with multivariate Tweedie distribution

NASA Astrophysics Data System (ADS)

Nor, Siti Rohani Mohd; Yusof, Fadhilah; Bahar, Arifah

2017-05-01

This study aims to measure the dependence between individual lifetimes by applying multivariate Tweedie distribution to the lifetime data. Dependence between lifetimes incorporated in the mortality model is a new form of idea that gives significant impact on the risk of the annuity portfolio which is actually against the idea of standard actuarial methods that assumes independent between lifetimes. Hence, this paper applies Tweedie family distribution to the portfolio of lifetimes to induce the dependence between lives. Tweedie distribution is chosen since it contains symmetric and non-symmetric, as well as light-tailed and heavy-tailed distributions. Parameter estimation is modified in order to fit the Tweedie distribution to the data. This procedure is developed by using method of moments. In addition, the comparison stage is made to check for the adequacy between the observed mortality and expected mortality. Finally, the importance of including systematic mortality risk in the model is justified by the Pearson's chi-squared test.

Measurements and modeling of charge carrier lifetime in compressed xenon

NASA Astrophysics Data System (ADS)

Pudov, A. O.; Abyzov, A. S.; Sokolov, S. A.; Davydov, L. N.; Rybka, A. V.; Kutny, V. E.; Melnikov, S. I.; Kholomyeyev, G. A.; Leonov, S. A.; Turchin, A. A.

2018-06-01

Gamma-spectrometers based on high-pressure xenon gas (HPXe) are proving themselves as a great potential alternative to the spectrometers based on high-purity germanium crystals and scintillators. The working medium for the high-resolution HPXe detectors, that is, xenon gas compressed up to pressure ∼50 bar and sometimes doped with hydrogen, methane or others gases, needs to be of very high purity. The gas purity level can be determined by direct measurements or, alternatively, its usability in gamma-spectrometers can be evaluated indirectly through the charge carrier (electron) lifetime measurements. Different approaches and specific setups have been used for the lifetime determination, most of those methods involve the measurement and analyses of individual pulses from ionizing particles registered in an ionization chamber filled with Xe. In the present paper, we report on the HPXe electron lifetime study carried out by using measurements in a cylindrical ionization chamber and the respective analytical charge transport model. Our results support the possibility of carrier lifetime determination in the cylindrical configuration. In addition, the voltage regimes for the use of the chamber in the spectroscopic mode were determined. The measurements were conducted in a two-electrode configuration for a range of pressure values (5 to 50 bar) for the Xe+0.25%H2 gas mixture of ∼6N purity. It is shown that in gases with relatively high values of the electron drift velocity and the electron lifetime, for example low-density gases, the charge collection time measurements can give significantly underestimated lifetime assessment. On the other hand, for the low drift velocity gases, they give much more accurate results. With the use of the analytical model, the electron lifetime was determined more precisely.

Stratospheric lifetime ratio of CFC-11 and CFC-12 from satellite and model climatologies

NASA Astrophysics Data System (ADS)

Hoffmann, L.; Hoppe, C. M.; Müller, R.; Dutton, G. S.; Gille, J. C.; Griessbach, S.; Jones, A.; Meyer, C. I.; Spang, R.; Volk, C. M.; Walker, K. A.

2014-06-01

Chlorofluorocarbons (CFCs) play a key role in stratospheric ozone loss and are strong infrared absorbers that contribute to global warming. The stratospheric lifetimes of CFCs are a measure of their global loss rates that are needed to determine global warming and ozone depletion potentials. We applied the tracer-tracer correlation approach to zonal mean climatologies from satellite measurements and model data to assess the lifetimes of CFCl3 (CFC-11) and CF2Cl2 (CFC-12). We present estimates of the CFC-11/CFC-12 lifetime ratio and the absolute lifetime of CFC-12, based on a reference lifetime of 52 yr for CFC-11. We analyzed climatologies from three satellite missions, the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), the HIgh Resolution Dynamics Limb Sounder (HIRDLS), and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). We found a CFC-11/CFC-12 lifetime ratio of 0.47±0.08 and a CFC-12 lifetime of 111(96-132) yr for ACE-FTS, a ratio of 0.46±0.07 and a lifetime of 112(97-133) yr for HIRDLS, and a ratio of 0.46±0.08 and a lifetime of 112(96-135) yr for MIPAS. The error-weighted, combined CFC-11/CFC-12 lifetime ratio is 0.47±0.04 and the CFC-12 lifetime estimate is 112(102-123) yr. These results agree with the recent Stratosphere-troposphere Processes And their Role in Climate (SPARC) reassessment, which recommends lifetimes of 52(43-67) yr and 102(88-122) yr, respectively. Having smaller uncertainties than the results from other recent studies, our estimates can help to better constrain CFC-11 and CFC-12 lifetime recommendations in future scientific studies and assessments. Furthermore, the satellite observations were used to validate first simulation results from a new coupled model system, which integrates a Lagrangian chemistry transport model into a climate model. For the coupled model we found a CFC-11/CFC-12 lifetime ratio of 0.48±0.07 and a CFC-12 lifetime of 110(95-129) yr, based on a ten-year perpetual

Stratospheric lifetime ratio of CFC-11 and CFC-12 from satellite and model climatologies

NASA Astrophysics Data System (ADS)

Hoffmann, L.; Hoppe, C. M.; Müller, R.; Dutton, G. S.; Gille, J. C.; Griessbach, S.; Jones, A.; Meyer, C. I.; Spang, R.; Volk, C. M.; Walker, K. A.

2014-11-01

Chlorofluorocarbons (CFCs) play a key role in stratospheric ozone loss and are strong infrared absorbers that contribute to global warming. The stratospheric lifetimes of CFCs are a measure of their stratospheric loss rates that are needed to determine global warming and ozone depletion potentials. We applied the tracer-tracer correlation approach to zonal mean climatologies from satellite measurements and model data to assess the lifetimes of CFCl3 (CFC-11) and CF2Cl2 (CFC-12). We present estimates of the CFC-11/CFC-12 lifetime ratio and the absolute lifetime of CFC-12, based on a reference lifetime of 52 years for CFC-11. We analyzed climatologies from three satellite missions, the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), the HIgh Resolution Dynamics Limb Sounder (HIRDLS), and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). We found a CFC-11/CFC-12 lifetime ratio of 0.47±0.08 and a CFC-12 lifetime of 112(96-133) years for ACE-FTS, a ratio of 0.46±0.07 and a lifetime of 113(97-134) years for HIRDLS, and a ratio of 0.46±0.08 and a lifetime of 114(98-136) years for MIPAS. The error-weighted, combined CFC-11/CFC-12 lifetime ratio is 0.46±0.04 and the CFC-12 lifetime estimate is 113(103-124) years. These results agree with the recent Stratosphere-troposphere Processes And their Role in Climate (SPARC) reassessment, which recommends lifetimes of 52(43-67) years and 102(88-122) years, respectively. Having smaller uncertainties than the results from other recent studies, our estimates can help to better constrain CFC-11 and CFC-12 lifetime recommendations in future scientific studies and assessments. Furthermore, the satellite observations were used to validate first simulation results from a new coupled model system, which integrates a Lagrangian chemistry transport model into a climate model. For the coupled model we found a CFC-11/CFC-12 lifetime ratio of 0.48±0.07 and a CFC-12 lifetime of 110(95-129) years

Potential for adult-based epidemiological studies to characterize overall cancer risks associated with a lifetime of CT scans.

PubMed

Shuryak, Igor; Lubin, Jay H; Brenner, David J

2014-06-01

Recent epidemiological studies have suggested that radiation exposure from pediatric CT scanning is associated with small excess cancer risks. However, the majority of CT scans are performed on adults, and most radiation-induced cancers appear during middle or old age, in the same age range as background cancers. Consequently, a logical next step is to investigate the effects of CT scanning in adulthood on lifetime cancer risks by conducting adult-based, appropriately designed epidemiological studies. Here we estimate the sample size required for such studies to detect CT-associated risks. This was achieved by incorporating different age-, sex-, time- and cancer type-dependent models of radiation carcinogenesis into an in silico simulation of a population-based cohort study. This approach simulated individual histories of chest and abdominal CT exposures, deaths and cancer diagnoses. The resultant sample sizes suggest that epidemiological studies of realistically sized cohorts can detect excess lifetime cancer risks from adult CT exposures. For example, retrospective analysis of CT exposure and cancer incidence data from a population-based cohort of 0.4 to 1.3 million (depending on the carcinogenic model) CT-exposed UK adults, aged 25-65 in 1980 and followed until 2015, provides 80% power for detecting cancer risks from chest and abdominal CT scans.

Stratospheric lifetime ratio of CFC-11 and CFC-12 from satellite and model climatologies

NASA Astrophysics Data System (ADS)

Hoffmann, Lars; Hoppe, Charlotte; Müller, Rolf; Dutton, Geoffrey S.; Gille, John C.; Griessbach, Sabine; Jones, Ashley; Meyer, Catrin I.; Spang, Reinhold; Volk, C. Michael; Walker, Kaley A.

2015-04-01

Chlorofluorocarbons (CFCs) play a key role in stratospheric ozone loss and are strong infrared absorbers that contribute to global warming. The stratospheric lifetimes of CFCs are a measure of their stratospheric loss rates that are needed to determine global warming and ozone depletion potentials. We applied the tracer-tracer correlation approach to zonal mean climatologies from satellite measurements and model data to assess the lifetimes of CFCl3 (CFC-11) and CF2Cl2 (CFC-12). We present new estimates of the CFC-11/CFC-12 lifetime ratio and the absolute lifetime of CFC-12, based on a reference lifetime of 52 yr for CFC-11. We analyzed climatologies from three satellite missions, the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), the HIgh Resolution Dynamics Limb Sounder (HIRDLS), and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). We found a CFC-11/CFC-12 lifetime ratio of 0.47 ± 0.08 and a CFC-12 lifetime of 112(96 - 133) yr for ACE-FTS, a ratio of 0.46 ± 0.07 and a lifetime of 113(97 - 134) yr for HIRDLS, and a ratio of 0.46 ± 0.08 and a lifetime of 114(98 - 136) yr for MIPAS. The error-weighted, combined CFC-11/CFC-12 lifetime ratio is 0.46 ± 0.04 and the CFC-12 lifetime estimate is 113(103 - 124) yr. These results are in excellent agreement with the recent Stratosphere-troposphere Processes And their Role in Climate (SPARC) reassessment, which recommends lifetimes of 52(43 - 67) yr for CFC-11 and 102(88 - 122) yr for CFC-12, respectively. Having smaller uncertainties than the results from other recent studies, our estimates can help to better constrain CFC-11 and CFC-12 lifetime recommendations in future scientific studies and assessments. Furthermore, the satellite observations were used to validate first simulation results from a new coupled model system, which integrates a Lagrangian chemistry transport model into a climate model. For the coupled EMAC/CLaMS model we found a CFC-11/CFC-12 lifetime ratio

Implications from Under-reporting at Lifetime, Death Certificate Notifications and Trace-back on the Recorded Incidence of a "Newly" Established Population-based Cancer Registry.

PubMed

Holleczek, B; Brenner, H

2016-01-01

Population-based cancer registries (CRs) are powerful tools for measuring cancer burden and progress against cancer. The study's objective was to investigate the effects of under-reporting at lifetime, death certificate notifications, and trace-back on the incidence a newly established population-based CR may record during its initial 15 years of operation. Using cancer data of nine CRs of the SEER programme we performed model calculations to investigate temporal trends of the recorded incidence that might be expected if registration started in 1995 with gradually increasing proportions of cancers reported to the CR. It was assumed that the CR obtains all death certificates providing cancer as the underlying cause of death. Different scenarios with regard to the development of the proportions of cancers reported to the CR and the use of trace-back were evaluated. Our model calculations demonstrated that the inclusion of cancers notified from death certificates which were diagnosed prior to the start of registration and which attribute to the incidence estimates of the year of death ('prevalent' cases) may compensate under-reporting typically observed right after the start of a CR. The recorded incidence may even be overestimated during the first years of registration, if large amounts of prevalent cancers are notified from death certificates (e.g. overestimation of lung cancer incidence by 8% and 21% in the first year of registration, if the proportions of cases reported were 50% and 70% in that year, overestimation of myeloma incidence still exceeding 5% after eight years of registration, if the proportion of cases reported to the CR had reached 97.5% after six years). Trace-back may effectively reduce the recorded surplus cancer cases. During the initial years of registration, the inclusion of prevalent cancers from death certificates may compensate the higher amount of underreporting right after the start of a CR. Accurate incidence estimates may nevertheless be

Lifetime Prevalence and Correlates of Schizophrenia-Spectrum, Affective, and Other Non-affective Psychotic Disorders in the Chinese Adult Population.

PubMed

Chang, Wing Chung; Wong, Corine Sau Man; Chen, Eric Yu Hai; Lam, Linda Chiu Wa; Chan, Wai Chi; Ng, Roger Man Kin; Hung, Se Fong; Cheung, Eric Fuk Chi; Sham, Pak Chung; Chiu, Helen Fung Kum; Lam, Ming; Lee, Edwin Ho Ming; Chiang, Tin Po; Chan, Lap Kei; Lau, Gary Kar Wai; Lee, Allen Ting Chun; Leung, Grace Tak Yu; Leung, Joey Shuk Yan; Lau, Joseph Tak Fai; van Os, Jim; Lewis, Glyn; Bebbington, Paul

2017-10-21

Lifetime prevalence of psychotic disorders varies widely across studies. Epidemiological surveys have rarely examined prevalences of specific psychotic disorders other than schizophrenia, and the majority used a single-phase design without employing clinical reappraisal interview for diagnostic verification. The current study investigated lifetime prevalence, correlates and service utilization of schizophrenia-spectrum, affective, and other non-affective psychotic disorders in a representative sample of community-dwelling Chinese adult population aged 16-75 years (N = 5719) based on a territory-wide, population-based household survey for mental disorders in Hong Kong. The survey adopted a 2-phase design comprising first-phase psychosis screening and second-phase diagnostic verification incorporating clinical information from psychiatrist-administered semi-structured interview and medical record review to ascertain DSM-IV lifetime diagnosis for psychotic disorders. Data on sociodemographics, psychosocial characteristics and service utilization were collected. Our results showed that lifetime prevalence was 2.47% for psychotic disorder overall, 1.25% for schizophrenia, 0.15% for delusional disorder, 0.38% for psychotic disorder not otherwise specified, 0.31% for bipolar disorder with psychosis, and 0.33% for depressive disorder with psychosis. Schizophrenia-spectrum disorder was associated with family history of psychosis, cigarette smoking and variables indicating socioeconomic disadvantage. Victimization experiences were significantly related to affective psychoses and other non-affective psychoses. Around 80% of participants with any psychotic disorder sought some kind of professional help for mental health problems in the past year. Using comprehensive diagnostic assessment involving interview and record data, our results indicate that approximately 2.5% of Chinese adult population had lifetime psychotic disorder which represents a major public health concern. �

Quantile based Tsallis entropy in residual lifetime

NASA Astrophysics Data System (ADS)

Khammar, A. H.; Jahanshahi, S. M. A.

2018-02-01

Tsallis entropy is a generalization of type α of the Shannon entropy, that is a nonadditive entropy unlike the Shannon entropy. Shannon entropy may be negative for some distributions, but Tsallis entropy can always be made nonnegative by choosing appropriate value of α. In this paper, we derive the quantile form of this nonadditive's entropy function in the residual lifetime, namely the residual quantile Tsallis entropy (RQTE) and get the bounds for it, depending on the Renyi's residual quantile entropy. Also, we obtain relationship between RQTE and concept of proportional hazards model in the quantile setup. Based on the new measure, we propose a stochastic order and aging classes, and study its properties. Finally, we prove characterizations theorems for some well known lifetime distributions. It is shown that RQTE uniquely determines the parent distribution unlike the residual Tsallis entropy.

Electromigration model for the prediction of lifetime based on the failure unit statistics in aluminum metallization

NASA Astrophysics Data System (ADS)

Park, Jong Ho; Ahn, Byung Tae

2003-01-01

A failure model for electromigration based on the "failure unit model" was presented for the prediction of lifetime in metal lines.The failure unit model, which consists of failure units in parallel and series, can predict both the median time to failure (MTTF) and the deviation in the time to failure (DTTF) in Al metal lines. The model can describe them only qualitatively. In our model, both the probability function of the failure unit in single grain segments and polygrain segments are considered instead of in polygrain segments alone. Based on our model, we calculated MTTF, DTTF, and activation energy for different median grain sizes, grain size distributions, linewidths, line lengths, current densities, and temperatures. Comparisons between our results and published experimental data showed good agreements and our model could explain the previously unexplained phenomena. Our advanced failure unit model might be further applied to other electromigration characteristics of metal lines.

Lifetime Prevalence of Posttraumatic Stress Disorder in Two American Indian Reservation Populations

PubMed Central

Beals, Janette; Manson, Spero M.; Croy, Calvin; Klein, Suzell A.; Whitesell, Nancy Rumbaugh; Mitchell, Christina M.

2015-01-01

Posttraumatic stress disorder (PTSD) has been found to be more common among American Indian populations than among other Americans. A complex diagnosis, the assessment methods for PTSD have varied across epidemiological studies, especially in terms of the trauma criteria. Here, we examined data from the American Indian Service Utilization, Psychiatric Epidemiology, Risk and Protective Factors Project (AI-SUPERPFP) to estimate the lifetime prevalence of PTSD in two culturally distinct American Indian reservation communities, using two formulas for calculating PTSD prevalence. The AI-SUPERPFP was a cross-sectional probability sample survey conducted between 1997 and 2000. Southwest (n = 1,446) and Northern Plains (n = 1,638) tribal members living on or near their reservations, aged 15–57 years at time of interview, were randomly sampled from tribal rolls. PTSD estimates were derived based on both the single worst and 3 worst traumas. Prevalence estimates varied by ascertainment method: single worst trauma (lifetime: 5.9% to 14.8%) versus 3 worst traumas (lifetime, 8.9% to 19.5%). Use of the 3-worst-event approach increased prevalence by 28.3% over the single-event method. PTSD was prevalent in these tribal communities. These results also serve to underscore the need to better understand the implications for PTSD prevalence with the current focus on a single worst event. PMID:23900893

A DISCUSSION ON DIFFERENT APPROACHES FOR ASSESSING LIFETIME RISKS OF RADON-INDUCED LUNG CANCER.

PubMed

Chen, Jing; Murith, Christophe; Palacios, Martha; Wang, Chunhong; Liu, Senlin

2017-11-01

Lifetime risks of radon induced lung cancer were assessed based on epidemiological approaches for Canadian, Swiss and Chinese populations, using the most recent vital statistic data and radon distribution characteristics available for each country. In the risk calculation, the North America residential radon risk model was used for the Canadian population, the European residential radon risk model for the Swiss population, the Chinese residential radon risk model for the Chinese population, and the EPA/BEIR-VI radon risk model for all three populations. The results were compared with the risk calculated from the International Commission on Radiological Protection (ICRP)'s exposure-to-risk conversion coefficients. In view of the fact that the ICRP coefficients were recommended for radiation protection of all populations, it was concluded that, generally speaking, lifetime absolute risks calculated with ICRP-recommended coefficients agree reasonably well with the range of radon induced lung cancer risk predicted by risk models derived from epidemiological pooling analyses. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

AN INDIVIDUAL-BASED MODEL OF COTTUS POPULATION DYNAMICS

EPA Science Inventory

We explored population dynamics of a southern Appalachian population of Cottus bairdi using a spatially-explicit, individual-based model. The model follows daily growth, mortality, and spawning of individuals as a function of flow and temperature. We modeled movement of juveniles...

IBSEM: An Individual-Based Atlantic Salmon Population Model

PubMed Central

Castellani, Marco; Heino, Mikko; Gilbey, John; Araki, Hitoshi; Svåsand, Terje; Glover, Kevin A.

2015-01-01

Ecology and genetics can influence the fate of individuals and populations in multiple ways. However, to date, few studies consider them when modelling the evolutionary trajectory of populations faced with admixture with non-local populations. For the Atlantic salmon, a model incorporating these elements is urgently needed because many populations are challenged with gene-flow from non-local and domesticated conspecifics. We developed an Individual-Based Salmon Eco-genetic Model (IBSEM) to simulate the demographic and population genetic change of an Atlantic salmon population through its entire life-cycle. Processes such as growth, mortality, and maturation are simulated through stochastic procedures, which take into account environmental variables as well as the genotype of the individuals. IBSEM is based upon detailed empirical data from salmon biology, and parameterized to reproduce the environmental conditions and the characteristics of a wild population inhabiting a Norwegian river. Simulations demonstrated that the model consistently and reliably reproduces the characteristics of the population. Moreover, in absence of farmed escapees, the modelled populations reach an evolutionary equilibrium that is similar to our definition of a ‘wild’ genotype. We assessed the sensitivity of the model in the face of assumptions made on the fitness differences between farm and wild salmon, and evaluated the role of straying as a buffering mechanism against the intrusion of farm genes into wild populations. These results demonstrate that IBSEM is able to capture the evolutionary forces shaping the life history of wild salmon and is therefore able to model the response of populations under environmental and genetic stressors. PMID:26383256

IBSEM: An Individual-Based Atlantic Salmon Population Model.

PubMed

Castellani, Marco; Heino, Mikko; Gilbey, John; Araki, Hitoshi; Svåsand, Terje; Glover, Kevin A

2015-01-01

Ecology and genetics can influence the fate of individuals and populations in multiple ways. However, to date, few studies consider them when modelling the evolutionary trajectory of populations faced with admixture with non-local populations. For the Atlantic salmon, a model incorporating these elements is urgently needed because many populations are challenged with gene-flow from non-local and domesticated conspecifics. We developed an Individual-Based Salmon Eco-genetic Model (IBSEM) to simulate the demographic and population genetic change of an Atlantic salmon population through its entire life-cycle. Processes such as growth, mortality, and maturation are simulated through stochastic procedures, which take into account environmental variables as well as the genotype of the individuals. IBSEM is based upon detailed empirical data from salmon biology, and parameterized to reproduce the environmental conditions and the characteristics of a wild population inhabiting a Norwegian river. Simulations demonstrated that the model consistently and reliably reproduces the characteristics of the population. Moreover, in absence of farmed escapees, the modelled populations reach an evolutionary equilibrium that is similar to our definition of a 'wild' genotype. We assessed the sensitivity of the model in the face of assumptions made on the fitness differences between farm and wild salmon, and evaluated the role of straying as a buffering mechanism against the intrusion of farm genes into wild populations. These results demonstrate that IBSEM is able to capture the evolutionary forces shaping the life history of wild salmon and is therefore able to model the response of populations under environmental and genetic stressors.

Lifetime pharmacokinetic model for hydrophobic contaminants in marine mammals

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

Hickie, B.E.; Mackay, D.; Koning, J. de

1999-11-01

A physiologically based pharmacokinetic model is developed that describes the uptake and release of a hydrophobic organic chemical by a marine mammal over its entire lifetime, i.e., from birth to death. This model is applied to polychlorinated biphenyls (PCBs) in the beluga whale (Delphinapterus leucas). The processes treated are growth; uptake from food, milk, and air; disposition of the chemical among arterial and venous blood, liver, muscle, blubber, and rapidly perfused tissues; and losses by metabolism, release in exhaled air; and by egestion. A separate model is developed for females, which includes pregnancy, birth, and lactation. Food consumption is deducedmore » from size, growth, and from activity-dependent bioenergetic data. The results obtained by simulating continuous PCB exposure over a 30-year period are in accordance with reported concentrations and show the importance of milk transfer to both mother and progeny and the tendency for continued accumulation over the animal's lifetime. Implications of the results are discussed, especially the need for improved data on diets, gut absorption characteristics, and various physiological parameters used in the model.« less

The 'Natural Laboratory', a tool for deciphering growth, lifetime and population dynamics in larger benthic foraminifera

NASA Astrophysics Data System (ADS)

Hohenegger, Johann

2015-04-01

The shells of symbiont-bearing larger benthic Foraminifera (LBF) represent the response to physiological requirements in dependence of environmental conditions. All compartments of the shell such as chambers and chamberlets accommodate the growth of the cell protoplasm and are adaptations for housing photosymbiotic algae. Investigations on the biology of LBF were predominantly based on laboratory studies. The lifetime of LBF under natural conditions is still unclear. LBF, which can build >100 chambers during their lifetime, are thought to live at least one year under natural conditions. This is supported by studies on population dynamics of eulittoral foraminifera. In species characterized by a time-restricted single reproduction period the mean size of specimens increases from small to large during lifetime simultaneously reducing individual number. This becomes more complex when two or more reproduction times are present within a one-year cycle leading to a mixture of abundant small individuals with few large specimens during the year, while keeping mean size more or less constant. This mixture is typical for most sublittoral megalospheric (gamonts or schizonts) LBF. Nothing is known on the lifetime of agamonts, the diploid asexually reproducing generation. In all hyaline LBF it is thought to be significantly longer than 1 year based on the large size and considering the mean chamber building rate of the gamont/schizonts. Observations on LBF under natural conditions have not been performed yet in the deeper sublittoral. This reflects the difficulties due to intense hydrodynamics that hinder deploying technical equipment for studies in the natural environment. Therefore, studying growth, lifetime and reproduction of sublittoral LBF under natural conditions can be performed using the so-called 'natural laboratory' in comparison with laboratory investigations. The best sampling method in the upper sublittoral from 5 to 70 m depth is by SCUBA diving. Irregular

Nanoparticle discrimination based on wavelength and lifetime-multiplexed cathodoluminescence microscopy.

PubMed

Garming, Mathijs W H; Weppelman, I Gerward C; de Boer, Pascal; Martínez, Felipe Perona; Schirhagl, Romana; Hoogenboom, Jacob P; Moerland, Robert J

2017-08-31

Nanomaterials can be identified in high-resolution electron microscopy images using spectrally-selective cathodoluminescence. Capabilities for multiplex detection can however be limited, e.g., due to spectral overlap or availability of filters. Also, the available photon flux may be limited due to degradation under electron irradiation. Here, we demonstrate single-pass cathodoluminescence-lifetime based discrimination of different nanoparticles, using a pulsed electron beam. We also show that cathodoluminescence lifetime is a robust parameter even when the nanoparticle cathodoluminescence intensity decays over an order of magnitude. We create lifetime maps, where the lifetime of the cathodoluminescence emission is correlated with the emission intensity and secondary-electron images. The consistency of lifetime-based discrimination is verified by also correlating the emission wavelength and the lifetime of nanoparticles. Our results show how cathodoluminescence lifetime provides an additional channel of information in electron microscopy.

Determinants of political trust: a lifetime learning model.

PubMed

Schoon, Ingrid; Cheng, Helen

2011-05-01

This article addresses questions regarding the origins of individual variations in political trust. Using 2 prospective longitudinal studies, we examine the associations between family background, general cognitive ability (g) and school motivation at early age, educational and occupational attainment in adulthood, and political trust measured in early and mid-adulthood in 2 large representative samples of the British population born in 1958 (N = 8,804) and in 1970 (N = 7,194). A lifetime learning model of political trust is tested using structural equation modeling to map the pathways linking early experiences to adult outcomes. Results show that political trust is shaped by both early and later experiences with institutions in society. Individuals who have accumulated more socioeconomic, educational, and motivational resources throughout their life course express higher levels of political trust than do those with fewer resources. (c) 2011 APA, all rights reserved.

Population characteristics of golden retriever lifetime study enrollees.

PubMed

Simpson, Melissa; Searfoss, Erin; Albright, Sharon; Brown, Diane E; Wolfe, Barbara; Clark, Nancy K; McCann, Susan E; Haworth, David; Guy, Mike; Page, Rod

2017-01-01

Studying cancer and other diseases poses a problem due to their protracted and multifactorial nature. Prospective studies are useful to investigate chronic disease processes since collection of lifestyle information, exposure data and co-incident health issues are collected before the condition manifests. The Golden Retriever Lifetime Study is one of the first prospective studies following privately-owned dogs throughout life to investigate the incidence and risk factors for disease outcomes, especially cancer.Owners of golden retrievers in the contiguous United States volunteered their dogs in early life. Owners and veterinarians complete online questionnaires about health status and lifestyle; dogs undergo a physical examination and collection of biological samples annually. The data presented summarize the initial study visits and the corresponding questionnaires for 3044 dogs in the cohort. The median age of dogs at enrollment was 14.0 months (interquartile range (IQR): 8-20 months). Approximately half of the population had undergone gonadectomy by their initial study visit. Medical conditions reported at enrollment consisted primarily of integumentary, gastrointestinal and urinary dysfunction. A large majority of the dogs have a record of having received preventive care (vaccines, parasiticides, flea and heartworm prevention) by the time of the initial study visit. Clinical pathology data were unremarkable. This study represents one of the first lifetime observational investigations in veterinary medicine. The population characteristics reported here indicate a healthy cohort of golden retrievers cared for by owners committed to their dogs' health. Data acquired over the study period will provide valuable information about genetic, dietary and environmental risk factors associated with disease in golden retrievers and a framework for future prospective studies in veterinary medicine.

Monte Carlo based method for fluorescence tomographic imaging with lifetime multiplexing using time gates

PubMed Central

Chen, Jin; Venugopal, Vivek; Intes, Xavier

2011-01-01

Time-resolved fluorescence optical tomography allows 3-dimensional localization of multiple fluorophores based on lifetime contrast while providing a unique data set for improved resolution. However, to employ the full fluorescence time measurements, a light propagation model that accurately simulates weakly diffused and multiple scattered photons is required. In this article, we derive a computationally efficient Monte Carlo based method to compute time-gated fluorescence Jacobians for the simultaneous imaging of two fluorophores with lifetime contrast. The Monte Carlo based formulation is validated on a synthetic murine model simulating the uptake in the kidneys of two distinct fluorophores with lifetime contrast. Experimentally, the method is validated using capillaries filled with 2.5nmol of ICG and IRDye™800CW respectively embedded in a diffuse media mimicking the average optical properties of mice. Combining multiple time gates in one inverse problem allows the simultaneous reconstruction of multiple fluorophores with increased resolution and minimal crosstalk using the proposed formulation. PMID:21483610

Lifetime risks for aneurysmal subarachnoid haemorrhage: multivariable risk stratification.

PubMed

Vlak, Monique H M; Rinkel, Gabriel J E; Greebe, Paut; Greving, Jacoba P; Algra, Ale

2013-06-01

The overall incidence of aneurysmal subarachnoid haemorrhage (aSAH) in western populations is around 9 per 100 000 person-years, which confers to a lifetime risk of around half per cent. Risk factors for aSAH are usually expressed as relative risks and suggest that absolute risks vary considerably according to risk factor profiles, but such estimates are lacking. We aimed to estimate incidence and lifetime risks of aSAH according to risk factor profiles. We used data from 250 patients admitted with aSAH and 574 sex-matched and age-matched controls, who were randomly retrieved from general practitioners files. We determined independent prognostic factors with multivariable logistic regression analyses and assessed discriminatory performance using the area under the receiver operating characteristic curve. Based on the prognostic model we predicted incidences and lifetime risks of aSAH for different risk factor profiles. The four strongest independent predictors for aSAH, namely current smoking (OR 6.0; 95% CI 4.1 to 8.6), a positive family history for aSAH (4.0; 95% CI 2.3 to 7.0), hypertension (2.4; 95% CI 1.5 to 3.8) and hypercholesterolaemia (0.2; 95% CI 0.1 to 0.4), were used in the final prediction model. This model had an area under the receiver operating characteristic curve of 0.73 (95% CI 0.69 to 0.76). Depending on sex, age and the four predictors, the incidence of aSAH ranged from 0.4/100 000 to 298/100 000 person-years and lifetime risk between 0.02% and 7.2%. The incidence and lifetime risk of aSAH in the general population varies widely according to risk factor profiles. Whether persons with high risks benefit from screening should be assessed in cost-effectiveness studies.

Usefulness of cancer-free survival in estimating the lifetime attributable risk of cancer incidence from radiation exposure.

PubMed

Seo, Songwon; Lee, Dal Nim; Jin, Young Woo; Lee, Won Jin; Park, Sunhoo

2018-05-11

Risk projection models estimating the lifetime cancer risk from radiation exposure are generally based on exposure dose, age at exposure, attained age, gender and study-population-specific factors such as baseline cancer risks and survival rates. Because such models have mostly been based on the Life Span Study cohort of Japanese atomic bomb survivors, the baseline risks and survival rates in the target population should be considered when applying the cancer risk. The survival function used in the risk projection models that are commonly used in the radiological protection field to estimate the cancer risk from medical or occupational exposure is based on all-cause mortality. Thus, it may not be accurate for estimating the lifetime risk of high-incidence but not life-threatening cancer with a long-term survival rate. Herein, we present the lifetime attributable risk (LAR) estimates of all solid cancers except thyroid cancer, thyroid cancer, and leukemia except chronic lymphocytic leukemia in South Korea for lifetime exposure to 1 mGy per year using the cancer-free survival function, as recently applied in the Fukushima health risk assessment by the World Health Organization. Compared with the estimates of LARs using an overall survival function solely based on all-cause mortality, the LARs of all solid cancers except thyroid cancer, and thyroid cancer evaluated using the cancer-free survival function, decreased by approximately 13% and 1% for men and 9% and 5% for women, respectively. The LAR of leukemia except chronic lymphocytic leukemia barely changed for either gender owing to the small absolute difference between its incidence and mortality. Given that many cancers have a high curative rate and low mortality rate, using a survival function solely based on all-cause mortality may cause an overestimation of the lifetime risk of cancer incidence. The lifetime fractional risk was robust against the choice of survival function.

A simple approach to lifetime learning in genetic programming-based symbolic regression.

PubMed

Azad, Raja Muhammad Atif; Ryan, Conor

2014-01-01

Genetic programming (GP) coarsely models natural evolution to evolve computer programs. Unlike in nature, where individuals can often improve their fitness through lifetime experience, the fitness of GP individuals generally does not change during their lifetime, and there is usually no opportunity to pass on acquired knowledge. This paper introduces the Chameleon system to address this discrepancy and augment GP with lifetime learning by adding a simple local search that operates by tuning the internal nodes of individuals. Although not the first attempt to combine local search with GP, its simplicity means that it is easy to understand and cheap to implement. A simple cache is added which leverages the local search to reduce the tuning cost to a small fraction of the expected cost, and we provide a theoretical upper limit on the maximum tuning expense given the average tree size of the population and show that this limit grows very conservatively as the average tree size of the population increases. We show that Chameleon uses available genetic material more efficiently by exploring more actively than with standard GP, and demonstrate that not only does Chameleon outperform standard GP (on both training and test data) over a number of symbolic regression type problems, it does so by producing smaller individuals and it works harmoniously with two other well-known extensions to GP, namely, linear scaling and a diversity-promoting tournament selection method.

Dynamical lifetimes of asteroids in retrograde orbits

NASA Astrophysics Data System (ADS)

Kankiewicz, Paweł; Włodarczyk, Ireneusz

2017-07-01

The population of known minor bodies in retrograde orbits (I > 90°) that are classified as asteroids is still growing. The aim of our study was to estimate the dynamical lifetimes of these bodies using the latest observational data, including astrometry and physical properties. We selected 25 asteroids with the best-determined orbital elements. We studied their dynamical evolution in the past and future for ±100 Myr (±1 Gyr for three particular cases). We first used orbit determination and cloning to produce swarms of test particles. These swarms were then input into long-term numerical integrations, and the orbital elements were averaged. Next, we collected the available thermal properties of our objects and we used them in an enhanced dynamical model with Yarkovsky forces. We also used a gravitational model for comparison. Finally, we estimated the median lifetimes of 25 asteroids. We found three objects whose retrograde orbits were stable with a dynamical lifetime τ ˜ 10-100 Myr. A large portion of the objects studied displayed smaller values of τ (τ ˜ 1 Myr). In addition, we studied the possible influence of the Yarkovsky effect on our results. We found that the Yarkovsky effect can have a significant influence on the lifetimes of asteroids in retrograde orbits. Because of the presence of this effect, it is possible that the median lifetimes of these objects are extended. Additionally, the changes in orbital elements, caused by Yarkovsky forces, appear to depend on the integration direction. To explain this more precisely, the same model based on new physical parameters, determined from future observations, will be required.

The estimated lifetime probability of acquiring human papillomavirus in the United States.

PubMed

Chesson, Harrell W; Dunne, Eileen F; Hariri, Susan; Markowitz, Lauri E

2014-11-01

Estimates of the lifetime probability of acquiring human papillomavirus (HPV) can help to quantify HPV incidence, illustrate how common HPV infection is, and highlight the importance of HPV vaccination. We developed a simple model, based primarily on the distribution of lifetime numbers of sex partners across the population and the per-partnership probability of acquiring HPV, to estimate the lifetime probability of acquiring HPV in the United States in the time frame before HPV vaccine availability. We estimated the average lifetime probability of acquiring HPV among those with at least 1 opposite sex partner to be 84.6% (range, 53.6%-95.0%) for women and 91.3% (range, 69.5%-97.7%) for men. Under base case assumptions, more than 80% of women and men acquire HPV by age 45 years. Our results are consistent with estimates in the existing literature suggesting a high lifetime probability of HPV acquisition and are supported by cohort studies showing high cumulative HPV incidence over a relatively short period, such as 3 to 5 years.

A model-based 'varimax' sampling strategy for a heterogeneous population.

PubMed

Akram, Nuzhat A; Farooqi, Shakeel R

2014-01-01

Sampling strategies are planned to enhance the homogeneity of a sample, hence to minimize confounding errors. A sampling strategy was developed to minimize the variation within population groups. Karachi, the largest urban agglomeration in Pakistan, was used as a model population. Blood groups ABO and Rh factor were determined for 3000 unrelated individuals selected through simple random sampling. Among them five population groups, namely Balochi, Muhajir, Pathan, Punjabi and Sindhi, based on paternal ethnicity were identified. An index was designed to measure the proportion of admixture at parental and grandparental levels. Population models based on index score were proposed. For validation, 175 individuals selected through stratified random sampling were genotyped for the three STR loci CSF1PO, TPOX and TH01. ANOVA showed significant differences across the population groups for blood groups and STR loci distribution. Gene diversity was higher across the sub-population model than in the agglomerated population. At parental level gene diversities are significantly higher across No admixture models than Admixture models. At grandparental level the difference was not significant. A sub-population model with no admixture at parental level was justified for sampling the heterogeneous population of Karachi.

Rapid Global Fitting of Large Fluorescence Lifetime Imaging Microscopy Datasets

PubMed Central

Warren, Sean C.; Margineanu, Anca; Alibhai, Dominic; Kelly, Douglas J.; Talbot, Clifford; Alexandrov, Yuriy; Munro, Ian; Katan, Matilda

2013-01-01

Fluorescence lifetime imaging (FLIM) is widely applied to obtain quantitative information from fluorescence signals, particularly using Förster Resonant Energy Transfer (FRET) measurements to map, for example, protein-protein interactions. Extracting FRET efficiencies or population fractions typically entails fitting data to complex fluorescence decay models but such experiments are frequently photon constrained, particularly for live cell or in vivo imaging, and this leads to unacceptable errors when analysing data on a pixel-wise basis. Lifetimes and population fractions may, however, be more robustly extracted using global analysis to simultaneously fit the fluorescence decay data of all pixels in an image or dataset to a multi-exponential model under the assumption that the lifetime components are invariant across the image (dataset). This approach is often considered to be prohibitively slow and/or computationally expensive but we present here a computationally efficient global analysis algorithm for the analysis of time-correlated single photon counting (TCSPC) or time-gated FLIM data based on variable projection. It makes efficient use of both computer processor and memory resources, requiring less than a minute to analyse time series and multiwell plate datasets with hundreds of FLIM images on standard personal computers. This lifetime analysis takes account of repetitive excitation, including fluorescence photons excited by earlier pulses contributing to the fit, and is able to accommodate time-varying backgrounds and instrument response functions. We demonstrate that this global approach allows us to readily fit time-resolved fluorescence data to complex models including a four-exponential model of a FRET system, for which the FRET efficiencies of the two species of a bi-exponential donor are linked, and polarisation-resolved lifetime data, where a fluorescence intensity and bi-exponential anisotropy decay model is applied to the analysis of live cell

Carrier lifetimes in polar InGaN-based LEDs

NASA Astrophysics Data System (ADS)

Wang, Lai; Jin, Jie; Hao, Zhibiao; Luo, Yi

2018-02-01

Measurement of carrier lifetime is very important to understand the physics in light-emitting diodes (LEDs), as it builds a link between carrier concentration and excitation power or current density. In this paper, we present our study on optical and electrical characterizations on carrier lifetimes in polar InGaN-based LEDs. First, a carrier rate equation model is proposed to explain the non-exponential nature of time-resolved photoluminescence (TRPL) decay curves, wherein exciton recombination is replaced by bimolecular recombination, considering the influence of polarization field on electron-hole pairs. Then, nonradiative recombination and radiative recombination coefficients can be deduced from fitting and used to calculate the radiative recombination efficiency. By comparing with the temperature-dependent photoluminescence (TDPL) and power-dependent photoluminescence (PDPL), it is found these three methods provide the consistent results. Second, differential carrier lifetimes depending on injection current are measured in commercial near-ultraviolet (NUV), blue and green LEDs. It is found that carrier lifetime is longer in green one and shorter in NUV one, which is attributed to the influence of polarization-induced quantum confined Stark effect (QCSE). This result implies the carrier density is higher in green LED while lower NUV LED, even the injection current is the same. By ignoring Auger recombination and fitting the efficiency-current and carrier lifetime-current curves simultaneously, the dependence of injection efficiency on carrier concentration in different LED samples are plotted. The NUV LED, which has the shallowest InGaN quantum well, actually exhibits the most serious efficiency droop versus carrier concentration. Then, the approaches to overcome the efficiency droop are discussed.

A Personalized Risk Stratification Platform for Population Lifetime Healthcare.

PubMed

Daowd, Ali; Abidi, Samina Raza; Abusharekh, Ashraf; Abidi, Syed Sibte Raza

2018-01-01

Chronic diseases are the leading cause of death worldwide. It is well understood that if modifiable risk factors are targeted, most chronic diseases can be prevented. Lifetime health is an emerging health paradigm that aims to assist individuals to achieve desired health targets, and avoid harmful lifecycle choices to mitigate the risk of chronic diseases. Early risk identification is central to lifetime health. In this paper, we present a digital health-based platform (PRISM) that leverages artificial intelligence, data visualization and mobile health technologies to empower citizens to self-assess, self-monitor and self-manage their overall risk of major chronic diseases and pursue personalized chronic disease prevention programs. PRISM offers risk assessment tools for 5 chronic conditions, 2 psychiatric disorders and 8 different cancers.

A CTRW-based model of time-resolved fluorescence lifetime imaging in a turbid medium

NASA Astrophysics Data System (ADS)

Chernomordik, Victor; Gandjbakhche, Amir H.; Hassan, Moinuddin; Pajevic, Sinisa; Weiss, George H.

2010-12-01

We develop an analytic model of time-resolved fluorescent imaging of photons migrating through a semi-infinite turbid medium bounded by an infinite plane in the presence of a single stationary point fluorophore embedded in the medium. In contrast to earlier models of fluorescent imaging in which photon motion is assumed to be some form of continuous diffusion process, the present analysis is based on a continuous-time random walk (CTRW) on a simple cubic lattice, the objective being to estimate the position and lifetime of the fluorophore. This can provide information related to local variations in pH and temperature with potential medical significance. Aspects of the theory were tested using time-resolved measurements of the fluorescence from small inclusions inside tissue-like phantoms. The experimental results were found to be in good agreement with theoretical predictions provided that the fluorophore was not located too close to the planar boundary, a common problem in many diffusive systems.

Lifetime Economic Burden of Rape Among U.S. Adults.

PubMed

Peterson, Cora; DeGue, Sarah; Florence, Curtis; Lokey, Colby N

2017-06-01

This study estimated the per-victim U.S. lifetime cost of rape. Data from previous studies was combined with current administrative data and 2011 U.S. National Intimate Partner and Sexual Violence Survey data in a mathematical model. Rape was defined as any lifetime completed or attempted forced penetration or alcohol- or drug-facilitated penetration, measured among adults not currently institutionalized. Costs included attributable impaired health, lost productivity, and criminal justice costs from the societal perspective. Average age at first rape was assumed to be 18 years. Future costs were discounted by 3%. The main outcome measures were the average per-victim (female and male) and total population discounted lifetime cost of rape. Secondary outcome measures were marginal outcome probabilities among victims (e.g., suicide attempt) and perpetrators (e.g., incarceration) and associated costs. Analysis was conducted in 2016. The estimated lifetime cost of rape was $122,461 per victim, or a population economic burden of nearly $3.1 trillion (2014 U.S. dollars) over victims' lifetimes, based on data indicating >25 million U.S. adults have been raped. This estimate included $1.2 trillion (39% of total) in medical costs; $1.6 trillion (52%) in lost work productivity among victims and perpetrators; $234 billion (8%) in criminal justice activities; and $36 billion (1%) in other costs, including victim property loss or damage. Government sources pay an estimated $1 trillion (32%) of the lifetime economic burden. Preventing sexual violence could avoid substantial costs for victims, perpetrators, healthcare payers, employers, and government payers. These findings can inform evaluations of interventions to reduce sexual violence. Published by Elsevier Inc.

Lifetime Economic Burden of Rape Among U.S. Adults

PubMed Central

Peterson, Cora; DeGue, Sarah; Florence, Curtis; Lokey, Colby N.

2017-01-01

Introduction This study estimated the per-victim U.S. lifetime cost of rape. Methods Data from previous studies was combined with current administrative data and 2011 U.S. National Intimate Partner and Sexual Violence Survey data in a mathematical model. Rape was defined as any lifetime completed or attempted forced penetration or alcohol- or drug-facilitated penetration, measured among adults not currently institutionalized. Costs included attributable impaired health, lost productivity, and criminal justice costs from the societal perspective. Average age at first rape was assumed to be 18 years. Future costs were discounted by 3%. The main outcome measures were the average per-victim (female and male) and total population discounted lifetime cost of rape. Secondary outcome measures were marginal outcome probabilities among victims (e.g., suicide attempt) and perpetrators (e.g., incarceration) and associated costs. Analysis was conducted in 2016. Results The estimated lifetime cost of rape was $122,461 per victim, or a population economic burden of nearly $3.1 trillion (2014 U.S. dollars) over victims’ lifetimes, based on data indicating >25 million U.S. adults have been raped. This estimate included $1.2 trillion (39% of total) in medical costs; $1.6 trillion (52%) in lost work productivity among victims and perpetrators; $234 billion (8%) in criminal justice activities; and $36 billion (1%) in other costs, including victim property loss or damage. Government sources pay an estimated $1 trillion (32%) of the lifetime economic burden. Conclusions Preventing sexual violence could avoid substantial costs for victims, perpetrators, healthcare payers, employers, and government payers. These findings can inform evaluations of interventions to reduce sexual violence. PMID:28153649

Cost-effectiveness of population based BRCA testing with varying Ashkenazi Jewish ancestry.

PubMed

Manchanda, Ranjit; Patel, Shreeya; Antoniou, Antonis C; Levy-Lahad, Ephrat; Turnbull, Clare; Evans, D Gareth; Hopper, John L; Macinnis, Robert J; Menon, Usha; Jacobs, Ian; Legood, Rosa

2017-11-01

Population-based BRCA1/BRCA2 testing has been found to be cost-effective compared with family history-based testing in Ashkenazi-Jewish women were >30 years old with 4 Ashkenazi-Jewish grandparents. However, individuals may have 1, 2, or 3 Ashkenazi-Jewish grandparents, and cost-effectiveness data are lacking at these lower BRCA prevalence estimates. We present an updated cost-effectiveness analysis of population BRCA1/BRCA2 testing for women with 1, 2, and 3 Ashkenazi-Jewish grandparents. Decision analysis model. Lifetime costs and effects of population and family history-based testing were compared with the use of a decision analysis model. 56% BRCA carriers are missed by family history criteria alone. Analyses were conducted for United Kingdom and United States populations. Model parameters were obtained from the Genetic Cancer Prediction through Population Screening trial and published literature. Model parameters and BRCA population prevalence for individuals with 3, 2, or 1 Ashkenazi-Jewish grandparent were adjusted for the relative frequency of BRCA mutations in the Ashkenazi-Jewish and general populations. Incremental cost-effectiveness ratios were calculated for all Ashkenazi-Jewish grandparent scenarios. Costs, along with outcomes, were discounted at 3.5%. The time horizon of the analysis is "life-time," and perspective is "payer." Probabilistic sensitivity analysis evaluated model uncertainty. Population testing for BRCA mutations is cost-saving in Ashkenazi-Jewish women with 2, 3, or 4 grandparents (22-33 days life-gained) in the United Kingdom and 1, 2, 3, or 4 grandparents (12-26 days life-gained) in the United States populations, respectively. It is also extremely cost-effective in women in the United Kingdom with just 1 Ashkenazi-Jewish grandparent with an incremental cost-effectiveness ratio of £863 per quality-adjusted life-years and 15 days life gained. Results show that population-testing remains cost-effective at the £20,000-30000 per quality

Fluorescent biosensor for the detection of hyaluronidase: intensity-based ratiometric sensing and fluorescence lifetime-based sensing using a long lifetime azadioxatriangulenium (ADOTA) fluorophore.

PubMed

Chib, Rahul; Mummert, Mark; Bora, Ilkay; Laursen, Bo W; Shah, Sunil; Pendry, Robert; Gryczynski, Ignacy; Borejdo, Julian; Gryczynski, Zygmunt; Fudala, Rafal

2016-05-01

In this report, we have designed a rapid and sensitive, intensity-based ratiometric sensing as well as lifetime-based sensing probe for the detection of hyaluronidase activity. Hyaluronidase expression is known to be upregulated in various pathological conditions. We have developed a fluorescent probe by heavy labeling of hyaluronic acid with a new orange/red-emitting organic azadioxatriangulenium (ADOTA) fluorophore, which exhibits a long fluorescence lifetime (∼20 ns). The ADOTA fluorophore in water has a peak fluorescence lifetime of ∼20 ns and emission spectra centered at 560 nm. The heavily ADOTA-labeled hyaluronic acid (HA-ADOTA) shows a red shift in the peak emission wavelength (605 nm), a weak fluorescence signal, and a shorter fluorescence lifetime (∼4 ns) due to efficient self-quenching and formation of aggregates. In the presence of hyaluronidase, the brightness and fluorescence lifetime of the sample increase with a blue shift in the peak emission to its original wavelength at 560 nm. The ratio of the fluorescence intensity of the HA-ADOTA probe at 560 and 605 nm can be used as the sensing method for the detection of hyaluronidase. The cleavage of the hyaluronic acid macromolecule reduces the energy migration between ADOTA molecules, as well as the degree of self-quenching and aggregation. This probe can be efficiently used for both intensity-based ratiometric sensing as well as fluorescence lifetime-based sensing of hyaluronidase. The proposed method makes it a rapid and sensitive assay, useful for analyzing levels of hyaluronidase in relevant clinical samples like urine or plasma. Graphical Abstract Scheme showing cleavage of HA-ADOTA probe by hyaluronidase and the change in the emission spectrum of HA-ADOTA probe before and after cleavage by hyaluronidase.

Remaining Lifetime After Recognition of Terminal Illness Depends on Diagnosis: A Nationwide Population-Based Cohort Study.

PubMed

Bell, Cathrine; Nielsen, Mette K; Neergaard, Mette A; Guldin, Mai-Britt; Jensen, Anders B

2017-01-01

Timely recognition of the terminal phase of life will benefit patients and caregivers as it may facilitate advance care planning and support. The objective of this study was to investigate the remaining lifetime of patients entering a physician-assessed terminal phase and to analyze variation in remaining lifetime according to diagnosis and sociodemographic factors. Danish National Health Registers were used to establish a prospective cohort of adult patients formally registered with drug reimbursement due to terminal illness in 2012 and followed until June 2014. Of the 11,062 included patients, the median remaining lifetime was 55 days and 37% of the patients died within the first month. The majority suffered from cancer (89%). Patients with a noncancer disease had the shortest remaining lifetime (17 days), considerably shorter than patients with cancer (59 days). Patients with prostate cancer had the longest remaining lifetime (76 days), whereas those with hematologic cancer had the shortest among cancer patients (41 days). Compared with lung cancer patients, the probability of death within 30 days were higher for patients with noncancer disease and lower for those with prostate or colorectal cancer. Male gender and high age were associated with higher risk of dying within 30 days. This study found a median remaining lifetime of 55 days after recognition of terminal illness. Remaining lifetime differed between cancer and noncancer patients and according to age and gender. Increased attention should be directed toward timely recognition of the transition into the terminal phase, especially for patients with noncancer disease. Copyright © 2016 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

A simple shape-free model for pore-size estimation with positron annihilation lifetime spectroscopy

NASA Astrophysics Data System (ADS)

Wada, Ken; Hyodo, Toshio

2013-06-01

Positron annihilation lifetime spectroscopy is one of the methods for estimating pore size in insulating materials. We present a shape-free model to be used conveniently for such analysis. A basic model in classical picture is modified by introducing a parameter corresponding to an effective size of the positronium (Ps). This parameter is adjusted so that its Ps-lifetime to pore-size relation merges smoothly with that of the well-established Tao-Eldrup model (with modification involving the intrinsic Ps annihilation rate) applicable to very small pores. The combined model, i.e., modified Tao-Eldrup model for smaller pores and the modified classical model for larger pores, agrees surprisingly well with the quantum-mechanics based extended Tao-Eldrup model, which deals with Ps trapped in and thermally equilibrium with a rectangular pore.

Fluorescence lifetime based bioassays

NASA Astrophysics Data System (ADS)

Meyer-Almes, Franz-Josef

2017-12-01

Fluorescence lifetime (FLT) is a robust intrinsic property and material constant of fluorescent matter. Measuring this important physical indicator has evolved from a laboratory curiosity to a powerful and established technique for a variety of applications in drug discovery, medical diagnostics and basic biological research. This distinct trend was mainly driven by improved and meanwhile affordable laser and detection instrumentation on the one hand, and the development of suitable FLT probes and biological assays on the other. In this process two essential working approaches emerged. The first one is primarily focused on high throughput applications employing biochemical in vitro assays with no requirement for high spatial resolution. The second even more dynamic trend is the significant expansion of assay methods combining highly time and spatially resolved fluorescence data by fluorescence lifetime imaging. The latter approach is currently pursued to enable not only the investigation of immortal tumor cell lines, but also specific tissues or even organs in living animals. This review tries to give an actual overview about the current status of FLT based bioassays and the wide range of application opportunities in biomedical and life science areas. In addition, future trends of FLT technologies will be discussed.

Lifetime prediction for the subsurface crack propagation using three-dimensional dynamic FEA model

NASA Astrophysics Data System (ADS)

Yin, Yuan; Chen, Yun-Xia; Liu, Le

2017-03-01

The subsurface crack propagation is one of the major interests for gear system research. The subsurface crack propagation lifetime is the number of cycles remaining for a spall to appear, which can be obtained through either stress intensity factor or accumulated plastic strain analysis. In this paper, the heavy loads are applied to the gear system. When choosing stress intensity factor, the high compressive stress suppresses Mode I stress intensities and severely reduces Mode II stress intensities in the heavily loaded lubricated contacts. Such that, the accumulated plastic strain is selected to calculate the subsurface crack propagation lifetime from the three-dimensional FEA model through ANSYS Workbench transient analysis. The three-dimensional gear FEA dynamic model with the subsurface crack is built through dividing the gears into several small elements. The calculation of the total cycles of the elements is proposed based on the time-varying accumulated plastic strain, which then will be used to calculate the subsurface crack propagation lifetime. During this process, the demonstration from a subsurface crack to a spall can be uncovered. In addition, different sizes of the elements around the subsurface crack are compared in this paper. The influences of the frictional coefficient and external torque on the crack propagation lifetime are also discussed. The results show that the lifetime of crack propagation decreases significantly when the external load T increasing from 100 N m to 150 N m. Given from the distributions of the accumulated plastic strain, the lifetime shares no significant difference when the frictional coefficient f ranging in 0.04-0.06.

Scalable Entity-Based Modeling of Population-Based Systems, Final LDRD Report

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

Cleary, A J; Smith, S G; Vassilevska, T K

2005-01-27

The goal of this project has been to develop tools, capabilities and expertise in the modeling of complex population-based systems via scalable entity-based modeling (EBM). Our initial focal application domain has been the dynamics of large populations exposed to disease-causing agents, a topic of interest to the Department of Homeland Security in the context of bioterrorism. In the academic community, discrete simulation technology based on individual entities has shown initial success, but the technology has not been scaled to the problem sizes or computational resources of LLNL. Our developmental emphasis has been on the extension of this technology to parallelmore » computers and maturation of the technology from an academic to a lab setting.« less

Estimating lifetime healthcare costs with morbidity data.

PubMed

Carreras, Marc; Ibern, Pere; Coderch, Jordi; Sánchez, Inma; Inoriza, Jose M

2013-10-25

In many developed countries, the economic crisis started in 2008 producing a serious contraction of the financial resources spent on healthcare. Identifying which individuals will require more resources and the moment in their lives these resources have to be allocated becomes essential. It is well known that a small number of individuals with complex healthcare needs consume a high percentage of health expenditures. Conversely, little is known on how morbidity evolves throughout life. The aim of this study is to introduce a longitudinal perspective to chronic disease management. Data used relate to the population of the county of Baix Empordà in Catalonia for the period 2004-2007 (average population was N = 88,858). The database included individual information on morbidity, resource consumption, costs and activity records. The population was classified using the Clinical Risk Groups (CRG) model. Future morbidity evolution was simulated under different assumptions using a stationary Markov chain. We obtained morbidity patterns for the lifetime and the distribution function of the random variable lifetime costs. Individual information on acute episodes, chronic conditions and multimorbidity patterns were included in the model. The probability of having a specific health status in the future (healthy, acute process or different combinations of chronic illness) and the distribution function of healthcare costs for the individual lifetime were obtained for the sample population. The mean lifetime cost for women was €111,936, a third higher than for men, at €81,566 (all amounts calculated in 2007 Euros). Healthy life expectancy at birth for females was 46.99, lower than for males (50.22). Females also spent 28.41 years of life suffering from some type of chronic disease, a longer period than men (21.9). Future morbidity and whole population costs can be reasonably predicted, combining stochastic microsimulation with a morbidity classification system. Potential

Estimating lifetime healthcare costs with morbidity data

PubMed Central

2013-01-01

Background In many developed countries, the economic crisis started in 2008 producing a serious contraction of the financial resources spent on healthcare. Identifying which individuals will require more resources and the moment in their lives these resources have to be allocated becomes essential. It is well known that a small number of individuals with complex healthcare needs consume a high percentage of health expenditures. Conversely, little is known on how morbidity evolves throughout life. The aim of this study is to introduce a longitudinal perspective to chronic disease management. Methods Data used relate to the population of the county of Baix Empordà in Catalonia for the period 2004–2007 (average population was N = 88,858). The database included individual information on morbidity, resource consumption, costs and activity records. The population was classified using the Clinical Risk Groups (CRG) model. Future morbidity evolution was simulated under different assumptions using a stationary Markov chain. We obtained morbidity patterns for the lifetime and the distribution function of the random variable lifetime costs. Individual information on acute episodes, chronic conditions and multimorbidity patterns were included in the model. Results The probability of having a specific health status in the future (healthy, acute process or different combinations of chronic illness) and the distribution function of healthcare costs for the individual lifetime were obtained for the sample population. The mean lifetime cost for women was €111,936, a third higher than for men, at €81,566 (all amounts calculated in 2007 Euros). Healthy life expectancy at birth for females was 46.99, lower than for males (50.22). Females also spent 28.41 years of life suffering from some type of chronic disease, a longer period than men (21.9). Conclusions Future morbidity and whole population costs can be reasonably predicted, combining stochastic microsimulation with a

Heuristic Modeling for TRMM Lifetime Predictions

NASA Technical Reports Server (NTRS)

Jordan, P. S.; Sharer, P. J.; DeFazio, R. L.

1996-01-01

Analysis time for computing the expected mission lifetimes of proposed frequently maneuvering, tightly altitude constrained, Earth orbiting spacecraft have been significantly reduced by means of a heuristic modeling method implemented in a commercial-off-the-shelf spreadsheet product (QuattroPro) running on a personal computer (PC). The method uses a look-up table to estimate the maneuver frequency per month as a function of the spacecraft ballistic coefficient and the solar flux index, then computes the associated fuel use by a simple engine model. Maneuver frequency data points are produced by means of a single 1-month run of traditional mission analysis software for each of the 12 to 25 data points required for the table. As the data point computations are required only a mission design start-up and on the occasion of significant mission redesigns, the dependence on time consuming traditional modeling methods is dramatically reduced. Results to date have agreed with traditional methods to within 1 to 1.5 percent. The spreadsheet approach is applicable to a wide variety of Earth orbiting spacecraft with tight altitude constraints. It will be particularly useful to such missions as the Tropical Rainfall Measurement Mission scheduled for launch in 1997, whose mission lifetime calculations are heavily dependent on frequently revised solar flux predictions.

Classification of customer lifetime value models using Markov chain

NASA Astrophysics Data System (ADS)

Permana, Dony; Pasaribu, Udjianna S.; Indratno, Sapto W.; Suprayogi

2017-10-01

A firm’s potential reward in future time from a customer can be determined by customer lifetime value (CLV). There are some mathematic methods to calculate it. One method is using Markov chain stochastic model. Here, a customer is assumed through some states. Transition inter the states follow Markovian properties. If we are given some states for a customer and the relationships inter states, then we can make some Markov models to describe the properties of the customer. As Markov models, CLV is defined as a vector contains CLV for a customer in the first state. In this paper we make a classification of Markov Models to calculate CLV. Start from two states of customer model, we make develop in many states models. The development a model is based on weaknesses in previous model. Some last models can be expected to describe how real characters of customers in a firm.

An agent-based computational model for tuberculosis spreading on age-structured populations

NASA Astrophysics Data System (ADS)

Graciani Rodrigues, C. C.; Espíndola, Aquino L.; Penna, T. J. P.

2015-06-01

In this work we present an agent-based computational model to study the spreading of the tuberculosis (TB) disease on age-structured populations. The model proposed is a merge of two previous models: an agent-based computational model for the spreading of tuberculosis and a bit-string model for biological aging. The combination of TB with the population aging, reproduces the coexistence of health states, as seen in real populations. In addition, the universal exponential behavior of mortalities curves is still preserved. Finally, the population distribution as function of age shows the prevalence of TB mostly in elders, for high efficacy treatments.

Recoil distance lifetime measurements in82Kr

NASA Astrophysics Data System (ADS)

Brüssermann, S.; Keinonen, J.; Hellmeister, H. P.; Lieb, K. P.

1982-12-01

The lifetimes τ=124±12, 6{-2/+4} and 380±100 ps of the E x ( I π )=3.46(8+), 2.92(6+) and 3.04(6-) MeV states, respectively, populated by the reaction76Ge(12C, α2 n) were measured with the recoil distance method. In addition upper lifetime limits were obtained for nine states. The measured lifetimes and energies indicate a band crossing at about I π =8+, probably arising from the alignment of two g 9/2 neutrons. For the 3.04 MeV 6- state as a second member of a band built on the 2.65 MeV 4- state the measured lifetime points to a two-quasiparticle configuration. The positive-parity states have been discussed in the frame of the interacting boson approximation, nuclear field theory and the cranked shell model.

Understanding the prevalence of lifetime abstinence from alcohol: An ecological study.

PubMed

Probst, Charlotte; Manthey, Jakob; Rehm, Jürgen

2017-09-01

The level of alcohol consumption and related burden in a country are strongly impacted by the prevalence of abstinence from alcohol use. The objective of this study was to characterize the association of lifetime abstinence from alcohol use with economic wealth (as measured in the gross domestic product [GDP]) and Muslim religion on a country level. An ecological study was performed using aggregate data of 183 countries for the year 2010. Lifetime abstinence among men and women was predicted using fractional response regression models with the natural logarithm of GDP-PPP (purchasing power parity) and the proportion of Muslim population as predictors. The models were further adjusted by the country's median age and World Health Organization region. Precision of prediction was investigated. Descriptive analyses showed a strong negative association between GDP-PPP and lifetime abstinence in countries without a Muslim majority and a GDP-PPP up to 20,000 international dollars. Regression models confirmed the negative association with GDP-PPP and showed a strong positive association between lifetime abstinence and the proportion of Muslim population. Stratified sensitivity analyses showed that in countries without a Muslim majority only GDP-PPP showed a statistically significant association whereas in Muslim majority countries only the proportion of Muslims was associated with the prevalence of lifetime abstinence. Particularly in countries with a lower GDP and without Muslim majority the prevalence of lifetime abstinence from alcohol use is strongly negatively associated with GDP-PPP. Future research should analyze the accordance in trends of GDP and lifetime abstinence over time. Copyright © 2017 Elsevier B.V. All rights reserved.

Understanding Past Population Dynamics: Bayesian Coalescent-Based Modeling with Covariates

PubMed Central

Gill, Mandev S.; Lemey, Philippe; Bennett, Shannon N.; Biek, Roman; Suchard, Marc A.

2016-01-01

Effective population size characterizes the genetic variability in a population and is a parameter of paramount importance in population genetics and evolutionary biology. Kingman’s coalescent process enables inference of past population dynamics directly from molecular sequence data, and researchers have developed a number of flexible coalescent-based models for Bayesian nonparametric estimation of the effective population size as a function of time. Major goals of demographic reconstruction include identifying driving factors of effective population size, and understanding the association between the effective population size and such factors. Building upon Bayesian nonparametric coalescent-based approaches, we introduce a flexible framework that incorporates time-varying covariates that exploit Gaussian Markov random fields to achieve temporal smoothing of effective population size trajectories. To approximate the posterior distribution, we adapt efficient Markov chain Monte Carlo algorithms designed for highly structured Gaussian models. Incorporating covariates into the demographic inference framework enables the modeling of associations between the effective population size and covariates while accounting for uncertainty in population histories. Furthermore, it can lead to more precise estimates of population dynamics. We apply our model to four examples. We reconstruct the demographic history of raccoon rabies in North America and find a significant association with the spatiotemporal spread of the outbreak. Next, we examine the effective population size trajectory of the DENV-4 virus in Puerto Rico along with viral isolate count data and find similar cyclic patterns. We compare the population history of the HIV-1 CRF02_AG clade in Cameroon with HIV incidence and prevalence data and find that the effective population size is more reflective of incidence rate. Finally, we explore the hypothesis that the population dynamics of musk ox during the Late

Reduced memory and attention performance in a population-based sample of young adults with a moderate lifetime use of cannabis, ecstasy and alcohol.

PubMed

Indlekofer, F; Piechatzek, M; Daamen, M; Glasmacher, C; Lieb, R; Pfister, H; Tucha, O; Lange, K W; Wittchen, H U; Schütz, C G

2009-07-01

Regular use of illegal drugs is suspected to cause cognitive impairments. Two substances have received heightened attention: 3,4-methylenedioxymethamphetamine (MDMA or 'ecstasy') and delta-9-tetrahydrocannabinol (THC or 'cannabis'). Preclinical evidence, as well as human studies examining regular ecstasy consumers, indicated that ecstasy use may have negative effects on learning, verbal memory and complex attentional functions. Cannabis has also been linked to symptoms of inattention and deficits in learning and memory. Most of the published studies in this field of research recruited participants by means of newspaper advertisements or by using word-of-mouth strategies. Because participants were usually aware that their drug use was critical to the research design, this awareness may have caused selection bias or created expectation effects. Focussing on attention and memory, this study aimed to assess cognitive functioning in a community-based representative sample that was derived from a large-scale epidemiological study. Available data concerning drug use history allowed sampling of subjects with varying degrees of lifetime drug experiences. Cognitive functioning was examined in 284 young participants, between 22 and 34 years. In general, their lifetime drug experience was moderate. Participants completed a neuropsychological test battery, including measures for verbal learning, memory and various attentional functions. Linear regression analysis was performed to investigate the relationship between cognitive functioning and lifetime experience of drug use. Ecstasy and cannabis use were significantly related to poorer episodic memory function in a dose-related manner. For attentional measures, decrements of small effect sizes were found. Error measures in tonic and phasic alertness tasks, selective attention task and vigilance showed small but significant effects, suggesting a stronger tendency to experience lapses of attention. No indication for differences in

Lifetime Incidence of CKD Stages 3–5 in the United States

PubMed Central

Grams, Morgan E.; Chow, Eric K.H.; Segev, Dorry L.; Coresh, Josef

2013-01-01

Background Lifetime risk estimates of chronic kidney disease (CKD) can motivate preventative behaviors at the individual level and forecast disease burden and health care utilization at the population level. Study Design Markov Monte Carlo model simulation study. Setting & Population Current U.S. black and white population. Model, Perspective, & Timeframe Markov models simulating kidney disease development, using an individual perspective and lifetime horizon. Outcomes Age-, sex- and race-specific residual lifetime risks of CKD stages 3a+ (eGFR<60 ml/min/1.73m2), 3b+ (eGFR<45 ml/min/1.73 m2), and 4+ (eGFR<30 ml/min/1.73m2), and end stage renal disease (ESRD). Measurements State transition probabilities of developing CKD and of dying prior to its development were modeled using: 1) mortality rates from National Vital Statistics Report, 2) mortality risk estimates from a 2-million person meta-analysis, and 3) CKD prevalence from National Health and Nutrition Examination Surveys. Incidence, prevalence, and mortality related to ESRD were supplied by the US Renal Disease System. Results At birth, the overall lifetime risks of CKD stages 3a+, 3b+, 4+, and ESRD were 59.1%, 33.6%, 11.5%, and 3.6%, respectively. Women experienced greater CKD risk yet lower ESRD risk than men; blacks of both sexes had markedly higher CKD stage 4+ and ESRD risk (lifetime risks for white men, white women, black men, and black women, respectively: 53.6%, 64.9%, 51.8%, and 63.6% [CKD stage 3a+]; 29.0%, 36.7%, 33.7%, and 40.2% [CKD stage 3b+]; 9.3%, 11.4%, 15.8%, and 18.5% [CKD stage 4+]; and 3.3%, 2.2%, 8.5%, and 7.8% [ESRD]). Risk of CKD increased with age, with approximately one-half of CKD stage 3a+ cases developing after 70 years of age. Limitations CKD incidence estimates were modeled from prevalence in the U.S. population. Conclusions In the U.S., the lifetime risk of developing CKD stage 3a+ is high, underscoring the importance of primary prevention and effective therapy to reduce CKD

Stochastic Analysis of Orbital Lifetimes of Spacecraft

NASA Technical Reports Server (NTRS)

Sasamoto, Washito; Goodliff, Kandyce; Cornelius, David

2008-01-01

A document discusses (1) a Monte-Carlo-based methodology for probabilistic prediction and analysis of orbital lifetimes of spacecraft and (2) Orbital Lifetime Monte Carlo (OLMC)--a Fortran computer program, consisting of a previously developed long-term orbit-propagator integrated with a Monte Carlo engine. OLMC enables modeling of variances of key physical parameters that affect orbital lifetimes through the use of probability distributions. These parameters include altitude, speed, and flight-path angle at insertion into orbit; solar flux; and launch delays. The products of OLMC are predicted lifetimes (durations above specified minimum altitudes) for the number of user-specified cases. Histograms generated from such predictions can be used to determine the probabilities that spacecraft will satisfy lifetime requirements. The document discusses uncertainties that affect modeling of orbital lifetimes. Issues of repeatability, smoothness of distributions, and code run time are considered for the purpose of establishing values of code-specific parameters and number of Monte Carlo runs. Results from test cases are interpreted as demonstrating that solar-flux predictions are primary sources of variations in predicted lifetimes. Therefore, it is concluded, multiple sets of predictions should be utilized to fully characterize the lifetime range of a spacecraft.

Positron lifetime setup based on DRS4 evaluation board

NASA Astrophysics Data System (ADS)

Petriska, M.; Sojak, S.; Slugeň, V.

2014-04-01

A digital positron lifetime setup based on DRS4 evaluation board designed at the Paul Scherrer Institute has been constructed and tested in the Positron annihilation laboratory Slovak University of Technology Bratislava. The high bandwidth, low power consumption and short readout time make DRS4 chip attractive for positron annihilation lifetime (PALS) setup, replacing traditional ADCs and TDCs. A software for PALS setup online and offline pulse analysis was developed with Qt,Qwt and ALGLIB libraries.

Extension of landscape-based population viability models to ecoregional scales for conservation planning

Treesearch

Thomas W. Bonnot; Frank R. III Thompson; Joshua Millspaugh

2011-01-01

Landscape-based population models are potentially valuable tools in facilitating conservation planning and actions at large scales. However, such models have rarely been applied at ecoregional scales. We extended landscape-based population models to ecoregional scales for three species of concern in the Central Hardwoods Bird Conservation Region and compared model...

Engineering a lifetime-based activatable probe for photoacoustic imaging

NASA Astrophysics Data System (ADS)

Morgounova, Ekaterina; Shao, Qi; Hackel, Benjamin; Ashkenazi, Shai

2013-02-01

High-resolution, high-penetration depth activatable probes are needed for in-vivo imaging of enzyme activity. In this paper, we will describe the contrast mechanism of a new photoacoustic activatable probe that changes its excitation lifetime upon activation. The excitation decay of methylene blue (MB), a chromophore commonly used in therapeutic and diagnostic applications, is probed by photoacoustic lifetime contrast imaging (PLCI). The monomer of the dye presents a high-quantum yield of intersystem-crossing and long lifetime (70 μs) whereas the dimer is statically quenched with a short lifetime (a few ns). This forms the basis of a highly sensitive contrast mechanism between monomers and dimers. Two dimerization models - one using sodium sulfate, the other using sodium dodecyl sulfate - were applied to control the monomer-to-dimer ratio in MB solutions. Preliminary results show that the photoacoustic signal of a dimer solution is efficiently suppressed (< 20 dB) due to their short lifetime compared to the monomer sample. Flash-photolysis of the same solutions reveals a 99% decrease in transient absorption confirming PLCI results. This contrast mechanism can be applied to design a MB dual-labeled activatable probe bound by an enzyme-specific cleavable peptide linker. When the probe is cleaved by its target, MB molecules will separate by molecular diffusion and recover their long excitation lifetime enabling their detection by PLCI. Our long-term goal is to investigate enzyme-specific imaging in small animals and establish pre-clinical data for translational research and implementation of the technology in clinical applications.

Accelerated lifetime test of vibration isolator made of Metal Rubber material

NASA Astrophysics Data System (ADS)

Ao, Hongrui; Ma, Yong; Wang, Xianbiao; Chen, Jianye; Jiang, Hongyuan

2017-01-01

The Metal Rubber material (MR) is a kind of material with nonlinear damping characteristics for its application in the field of aerospace, petrochemical industry and so on. The study on the lifetime of MR material is impendent to its application in engineering. Based on the dynamic characteristic of MR, the accelerated lifetime experiments of vibration isolators made of MR working under random vibration load were conducted. The effects of structural parameters of MR components on the lifetime of isolators were studied and modelled with the fitting curves of degradation data. The lifetime prediction methods were proposed based on the models.

Lifetime Risk of Symptomatic Hand Osteoarthritis: The Johnston County Osteoarthritis Project

PubMed Central

Qin, Jin; Barbour, Kamil E.; Murphy, Louise B.; Nelson, Amanda E.; Schwartz, Todd A.; Helmick, Charles G.; Allen, Kelli D.; Renner, Jordan B.; Baker, Nancy A; Jordan, Joanne M.

2017-01-01

Objective Symptomatic hand osteoarthritis (SHOA) is a common condition that affects hand strength and function, and causes disability in activities of daily living. Prior studies have estimated lifetime risk for symptomatic knee and hip osteoarthritis to be 45% and 25% respectively. The objective of this study is to estimate overall lifetime risk for SHOA and stratified lifetime risk by potential risk factors. Methods We analyzed data for 2,218 adults ≥ 45 years in the Johnston County Osteoarthritis Project, a population-based prospective cohort study in residents of Johnston County, North Carolina. Data were collected in two cycles (1999–2004 and 2005–2010). SHOA was defined as having both self-reported symptoms and radiographic OA in the same hand. Lifetime risk, defined as the proportion of the population who will develop SHOA in at least one hand by age 85, was estimated from models using generalized estimating equations methodology. Results Overall, the lifetime risk of SHOA is 39.8% (95% confidence interval (CI): 34.4, 45.3). Nearly one in two women (47.2%; 95% CI: 40.6, 53.9) will develop SHOA by age 85 compared with one in four men (24.6%; 95% CI: 19.5, 30.5). Race-specific estimates are 41.4% (95% CI: 35.5, 47.6) among whites and 29.2% (95% CI: 20.5, 39.7) among blacks. Lifetime risk among individuals with obesity (47.1%, 95% CI: 37.8, 56.7) is 11 percentage point higher than those without obesity (36.1%, 95% CI: 29.7, 42.9). Conclusion These findings demonstrate the substantial burden of SHOA overall and in subgroups. Increased use of public health and clinical interventions is needed to address its impact. PMID:28470947

UV lifetime demonstrator for space-based applications

NASA Astrophysics Data System (ADS)

Albert, Michael; Puffenburger, Kent; Schum, Tom; Fitzpatrick, Fran; Litvinovitch, Slava; Jones, Darrell; Rudd, Joseph; Hovis, Floyd

2016-05-01

A long-lived UV laser is an enabling technology for a number of high-priority, space-based lidar instruments. These include next generation cloud and aerosol lidars that incorporates a UV channel, direct detection 3-D wind lidars, and ozone DIAL (differential absorption lidar) systems. In previous SBIR funded work we developed techniques for increasing the survivability of components in high power UV lasers and demonstrated improved operational lifetimes. In this Phase III ESTO funded effort we are designing and building a TRL (Technology Readiness Level) 6 demonstrator that will have increased output power and a space-qualifiable package that is mechanically robust and thermally-stable. For full space compatibility, thermal control will be through pure conductive cooling. Contamination control processes and optical coatings will be chosen that are compatible with lifetimes in excess of 1 billion shots. The 1064nm output will be frequency tripled to provide greater than 100 mJ pulses of 355 nm light at 150 Hz. The laser module build was completed in the third quarter of 2015 at which time a series of life tests were initiated. The first phase of the lifetime testing is a 532 nm only test that is expected to complete in April 2016. The 532 nm lifetest will be followed by a 4 month half power UV life test and then a four month full power UV life test. The lifetime tests will be followed by thermal/vacuum (TVAC) and vibration testing to demonstrate that the laser optics module design is at TRL 6.

Lifetime Earnings Estimates for Men and Women in the United States: 1979.

ERIC Educational Resources Information Center

Burkhead, Dan L.

1983-01-01

This report presents estimates of expected lifetime earnings based on data collected in the March Current Population Survey by age, sex, and educational attainment for 1978, 1979, and 1980. The text describes the data tables and charts, methodology, and limitations of the data. The eight figures and five detailed tables present lifetime earning…

Individual-based modelling of population growth and diffusion in discrete time.

PubMed

Tkachenko, Natalie; Weissmann, John D; Petersen, Wesley P; Lake, George; Zollikofer, Christoph P E; Callegari, Simone

2017-01-01

Individual-based models (IBMs) of human populations capture spatio-temporal dynamics using rules that govern the birth, behavior, and death of individuals. We explore a stochastic IBM of logistic growth-diffusion with constant time steps and independent, simultaneous actions of birth, death, and movement that approaches the Fisher-Kolmogorov model in the continuum limit. This model is well-suited to parallelization on high-performance computers. We explore its emergent properties with analytical approximations and numerical simulations in parameter ranges relevant to human population dynamics and ecology, and reproduce continuous-time results in the limit of small transition probabilities. Our model prediction indicates that the population density and dispersal speed are affected by fluctuations in the number of individuals. The discrete-time model displays novel properties owing to the binomial character of the fluctuations: in certain regimes of the growth model, a decrease in time step size drives the system away from the continuum limit. These effects are especially important at local population sizes of <50 individuals, which largely correspond to group sizes of hunter-gatherers. As an application scenario, we model the late Pleistocene dispersal of Homo sapiens into the Americas, and discuss the agreement of model-based estimates of first-arrival dates with archaeological dates in dependence of IBM model parameter settings.

A lifetime experience of violence and adverse reproductive outcomes: findings from population surveys in India.

PubMed

Yoshikawa, K; Agrawal, N R; Poudel, K C; Jimba, M

2012-06-01

Intimate partner violence (IPV) is a global public health issue that threatens the reproductive health of women. Despite a growing demand for research on the potential threat of IPV in relation to adverse reproductive outcomes, there have been no population-based studies of India. The current study analyzed the National Family Health Survey 3, which contained detailed information on types of violence in relation to the single question of pregnancy outcomes. The dataset was used to assess the association between a lifetime experience of IPV and terminated pregnancies among married Indian women. Multiple logistic regression analysis was then used to assess the association between these variables, controlling for socio-demographic characteristics. Results showed that 39.6% of Indian women have experienced violence by their husbands, while 18.3% of women have terminated a pregnancy during their lifetimes. The odds ratio of a terminated pregnancy among women who had experienced any type of partner violence was 1.62 (95% CI (confidence interval) = 1.51-1.73). All combinations of violence except a combination of emotional and sexual violence were associated with an increased risk of a terminated pregnancy. These results suggest that prevention of IPV would reduce the high incidence of terminated pregnancies, thus improving maternal health in India.

Evaluation of Observed and Modelled Aerosol Lifetimes Using Radioactive Tracers of Opportunity and an Ensemble of 19 Global Models

NASA Technical Reports Server (NTRS)

Kristiansen, N. I.; Stohl, A.; Olivie, D. J. L.; Croft, B.; Sovde, O. A.; Klein, H.; Christoudias, T.; Kunkel, D.; Leadbetter, S. J.; Lee, Y. H.;

NOx Lifetime During WINTER

NASA Astrophysics Data System (ADS)

Kenagy, H. S.; Sparks, T.; Ebben, C. J.; Wooldridge, P. J.; Lopez-Hilfiker, F.; Lee, B. H.; Thornton, J. A.; McDuffie, E. E.; Fibiger, D. L.; Brown, S. S.; Montzka, D. D.; Weinheimer, A. J.; Apel, E. C.; Jaegle, L.; Cohen, R. C.

2017-12-01

The study of the lifetime and fate of NOx (=NO + NO2) is important for understanding its persistence and distribution. This requires an understanding of the balance of NOx sinks. Although urban NOx lifetimes are relatively well understood during summertime conditions, wintertime NOx chemistry has been comparatively less studied. We used measurements of NOx and its oxidation products from the aircraft-based WINTER (Wintertime INvestigation of Transport, Emissions, and Reactivity) campaign over the northeastern US during February-March 2015 to help constrain NOx lifetime during wintertime conditions when days are shorter, actinic flux is reduced, and temperatures are colder. By analyzing the marine outflow from the NYC-DC corridor, we learn that wintertime NOx has a long lifetime, is much longer-lived during the day than at night, and its lifetime is controlled during both periods by NOx conversion to nitric acid (HNO3) as the primary NOx sink. We also employ a two-box model to constrain the wintertime plume dilution rate and HNO3 deposition rate. Additionally, analysis of the nighttime Ox budget suggests that approximately 10% of O3 is lost overnight through N2O5 dark reactions that produce HNO3.

Expectation Maximization Algorithm for Box-Cox Transformation Cure Rate Model and Assessment of Model Misspecification Under Weibull Lifetimes.

PubMed

Pal, Suvra; Balakrishnan, Narayanaswamy

2018-05-01

In this paper, we develop likelihood inference based on the expectation maximization algorithm for the Box-Cox transformation cure rate model assuming the lifetimes to follow a Weibull distribution. A simulation study is carried out to demonstrate the performance of the proposed estimation method. Through Monte Carlo simulations, we also study the effect of model misspecification on the estimate of cure rate. Finally, we analyze a well-known data on melanoma with the model and the inferential method developed here.

Evaluation of observed and modelled aerosol lifetimes using radioactive tracers of opportunity and an ensemble of 19 global models

DOE PAGES

Kristiansen, N. I.; Stohl, A.; Olivie, D. J. L.; ...

2016-03-17

Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 ( 137Cs) and xenon-133 ( 133Xe) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to theirmore » available aerosol surface area. 137Cs size distribution measurements taken close to the power plant suggested that accumulation-mode (AM) sulfate aerosols were the main carriers of cesium. Hence, 137Cs can be used as a proxy tracer for the AM sulfate aerosol's fate in the atmosphere. In contrast, the noble gas 133Xe behaves almost like a passive transport tracer. Global surface measurements of the two radioactive isotopes taken over several months after the release allow the derivation of a lifetime of the carrier aerosol. We compare this to the lifetimes simulated by 19 different atmospheric transport models initialized with identical emissions of 137Cs that were assigned to an aerosol tracer with each model's default properties of AM sulfate, and 133Xe emissions that were assigned to a passive tracer. We investigate to what extent the modelled sulfate tracer can reproduce the measurements, especially with respect to the observed loss of aerosol mass with time. Modelled 137Cs and 133Xe concentrations sampled at the same location and times as station measurements allow a direct comparison between measured and modelled aerosol lifetime. The e-folding lifetime τ e, calculated from station measurement data taken between 2 and 9 weeks after the start of the emissions, is 14.3 days

Predicting the breakdown strength and lifetime of nanocomposites using a multi-scale modeling approach

NASA Astrophysics Data System (ADS)

Huang, Yanhui; Zhao, He; Wang, Yixing; Ratcliff, Tyree; Breneman, Curt; Brinson, L. Catherine; Chen, Wei; Schadler, Linda S.

2017-08-01

It has been found that doping dielectric polymers with a small amount of nanofiller or molecular additive can stabilize the material under a high field and lead to increased breakdown strength and lifetime. Choosing appropriate fillers is critical to optimizing the material performance, but current research largely relies on experimental trial and error. The employment of computer simulations for nanodielectric design is rarely reported. In this work, we propose a multi-scale modeling approach that employs ab initio, Monte Carlo, and continuum scales to predict the breakdown strength and lifetime of polymer nanocomposites based on the charge trapping effect of the nanofillers. The charge transfer, charge energy relaxation, and space charge effects are modeled in respective hierarchical scales by distinctive simulation techniques, and these models are connected together for high fidelity and robustness. The preliminary results show good agreement with the experimental data, suggesting its promise for use in the computer aided material design of high performance dielectrics.

A new lifetime estimation model for a quicker LED reliability prediction

NASA Astrophysics Data System (ADS)

Hamon, B. H.; Mendizabal, L.; Feuillet, G.; Gasse, A.; Bataillou, B.

2014-09-01

LED reliability and lifetime prediction is a key point for Solid State Lighting adoption. For this purpose, one hundred and fifty LEDs have been aged for a reliability analysis. LEDs have been grouped following nine current-temperature stress conditions. Stress driving current was fixed between 350mA and 1A and ambient temperature between 85C and 120°C. Using integrating sphere and I(V) measurements, a cross study of the evolution of electrical and optical characteristics has been done. Results show two main failure mechanisms regarding lumen maintenance. The first one is the typically observed lumen depreciation and the second one is a much more quicker depreciation related to an increase of the leakage and non radiative currents. Models of the typical lumen depreciation and leakage resistance depreciation have been made using electrical and optical measurements during the aging tests. The combination of those models allows a new method toward a quicker LED lifetime prediction. These two models have been used for lifetime predictions for LEDs.

Cost effectiveness of population based BRCA1 founder mutation testing in Sephardi Jewish women.

PubMed

Patel, Shreeya; Legood, Rosa; Evans, D Gareth; Turnbull, Clare; Antoniou, Antonis C; Menon, Usha; Jacobs, Ian; Manchanda, Ranjit

2018-04-01

Population-based BRCA1/BRCA2 founder-mutation testing has been demonstrated as cost effective compared with family history based testing in Ashkenazi Jewish women. However, only 1 of the 3 Ashkenazi Jewish BRCA1/BRCA2 founder mutations (185delAG[c.68_69delAG]), 5382insC[c.5266dupC]), and 6174delT[c.5946delT]) is found in the Sephardi Jewish population (185delAG[c.68_69delAG]), and the overall prevalence of BRCA mutations in the Sephardi Jewish population is accordingly lower (0.7% compared with 2.5% in the Ashkenazi Jewish population). Cost-effectiveness analyses of BRCA testing have not previously been performed at these lower BRCA prevalence levels seen in the Sephardi Jewish population. Here we present a cost-effectiveness analysis for UK and US populations comparing population testing with clinical criteria/family history-based testing in Sephardi Jewish women. A Markov model was built comparing the lifetime costs and effects of population-based BRCA1 testing, with testing using family history-based clinical criteria in Sephardi Jewish women aged ≥30 years. BRCA1 carriers identified were offered magnetic resonance imaging/mammograms and risk-reducing surgery. Costs are reported at 2015 prices. Outcomes include breast cancer, ovarian cancer, and excess deaths from heart disease. All costs and outcomes are discounted at 3.5%. The time horizon is lifetime, and perspective is payer. The incremental cost-effectiveness ratio per quality-adjusted life-year was calculated. Parameter uncertainty was evaluated through 1-way and probabilistic sensitivity analysis. Population testing resulted in gain in life expectancy of 12 months (quality-adjusted life-year = 1.00). The baseline discounted incremental cost-effectiveness ratio for UK population-based testing was £67.04/quality-adjusted life-year and for US population was $308.42/quality-adjusted life-year. Results were robust in the 1-way sensitivity analysis. The probabilistic sensitivity analysis showed 100% of

Alternating event processes during lifetimes: population dynamics and statistical inference.

PubMed

Shinohara, Russell T; Sun, Yifei; Wang, Mei-Cheng

2018-01-01

In the literature studying recurrent event data, a large amount of work has been focused on univariate recurrent event processes where the occurrence of each event is treated as a single point in time. There are many applications, however, in which univariate recurrent events are insufficient to characterize the feature of the process because patients experience nontrivial durations associated with each event. This results in an alternating event process where the disease status of a patient alternates between exacerbations and remissions. In this paper, we consider the dynamics of a chronic disease and its associated exacerbation-remission process over two time scales: calendar time and time-since-onset. In particular, over calendar time, we explore population dynamics and the relationship between incidence, prevalence and duration for such alternating event processes. We provide nonparametric estimation techniques for characteristic quantities of the process. In some settings, exacerbation processes are observed from an onset time until death; to account for the relationship between the survival and alternating event processes, nonparametric approaches are developed for estimating exacerbation process over lifetime. By understanding the population dynamics and within-process structure, the paper provide a new and general way to study alternating event processes.

A CMOS Luminescence Intensity and Lifetime Dual Sensor Based on Multicycle Charge Modulation.

PubMed

Fu, Guoqing; Sonkusale, Sameer R

2018-06-01

Luminescence plays an important role in many scientific and industrial applications. This paper proposes a novel complementary metal-oxide-semiconductor (CMOS) sensor chip that can realize both luminescence intensity and lifetime sensing. To enable high sensitivity, we propose parasitic insensitive multicycle charge modulation scheme for low-light lifetime extraction benefiting from simplicity, accuracy, and compatibility with deeply scaled CMOS process. The designed in-pixel capacitive transimpedance amplifier (CTIA) based structure is able to capture the weak luminescence-induced voltage signal by accumulating photon-generated charges in 25 discrete gated 10-ms time windows and 10-μs pulsewidth. A pinned photodiode on chip with 1.04 pA dark current is utilized for luminescence detection. The proposed CTIA-based circuitry can achieve 2.1-mV/(nW/cm 2 ) responsivity and 4.38-nW/cm 2 resolution at 630 nm wavelength for intensity measurement and 45-ns resolution for lifetime measurement. The sensor chip is employed for measuring time constants and luminescence lifetimes of an InGaN-based white light-emitting diode at different wavelengths. In addition, we demonstrate accurate measurement of the lifetime of an oxygen sensitive chromophore with sensitivity to oxygen concentration of 7.5%/ppm and 6%/ppm in both intensity and lifetime domain. This CMOS-enabled oxygen sensor was then employed to test water quality from different sources (tap water, lakes, and rivers).

Fluorescence Lifetime Imaging Microscopy Using Near-Infrared Contrast Agents

PubMed Central

Nothdurft, Ralph; Sarder, Pinaki; Bloch, Sharon; Culver, Joseph; Achilefu, Samuel

2013-01-01

Although single-photon fluorescence lifetime imaging microscopy (FLIM) is widely used to image molecular processes using a wide range of excitation wavelengths, the captured emission of this technique is confined to the visible spectrum. Here, we explore the feasibility of utilizing near-infrared (NIR) fluorescent molecular probes with emission >700 nm for FLIM of live cells. The confocal microscope is equipped with a 785 nm laser diode, a red-enhanced photomultiplier tube, and a time-correlated single photon counting card. We demonstrate that our system reports the lifetime distributions of NIR fluorescent dyes, cypate and DTTCI, in cells. In cells labeled separately or jointly with these dyes, NIR FLIM successfully distinguishes their lifetimes, providing a method to sort different cell populations. In addition, lifetime distributions of cells co-incubated with these dyes allow estimate of the dyes’ relative concentrations in complex cellular microenvironments. With the heightened interest in fluorescence lifetime-based small animal imaging using NIR fluorophores, this technique further serves as a bridge between in vitro spectroscopic characterization of new fluorophore lifetimes and in vivo tissue imaging. PMID:22788550

Estimating the long-term effects of in vitro fertilization in Greece: an analysis based on a lifetime-investment model

PubMed Central

Fragoulakis, Vassilis; Maniadakis, Nikolaos

2013-01-01

Objective To quantify the economic effects of a child conceived by in vitro fertilization (IVF) in terms of net tax revenue from the state’s perspective in Greece. Methods Based on previous international experience, a mathematical model was developed to assess the lifetime productivity of a single individual and his/her lifetime transactions with governmental agencies. The model distinguished among three periods in the economic life cycle of an individual: (1) early life, when the government primarily contributes resources through child tax credits, health care, and educational expenses; (2) employment, when individuals begin returning resources through taxes; and (3) retirement, when the government expends additional resources on pensions and health care. The cost of a live birth with IVF was based on the modification of a previously published model developed by the authors. All outcomes were discounted at a 3% discount rate. The data inputs – namely, the economic or demographic variables – were derived from the National Statistical Secretariat of Greece and other relevant sources. To deal with uncertainty, bias-corrected uncertainty intervals (UIs) were calculated based on 5000 Monte Carlo simulations. In addition, to examine the robustness of our results, other one-way sensitivity analyses were also employed. Results The cost of IVF per birth was estimated at €17,015 (95% UI: €13,932–€20,200). The average projected income generated by an individual throughout his/her productive life was €258,070 (95% UI: €185,376–€339,831). In addition, his/her life tax contribution was estimated at €133,947 (95% UI: €100,126–€177,375), while the discounted governmental expenses for elderly and underage individuals were €67,624 (95% UI: €55,211–€83,930). Hence, the net present value of IVF was €60,435 (95% UI: €33,651–€94,330), representing a 182% net return on investment. Results remained constant under various assumptions for the

An individual-based model of zebrafish population dynamics accounting for energy dynamics.

PubMed

Beaudouin, Rémy; Goussen, Benoit; Piccini, Benjamin; Augustine, Starrlight; Devillers, James; Brion, François; Péry, Alexandre R R

2015-01-01

Developing population dynamics models for zebrafish is crucial in order to extrapolate from toxicity data measured at the organism level to biological levels relevant to support and enhance ecological risk assessment. To achieve this, a dynamic energy budget for individual zebrafish (DEB model) was coupled to an individual based model of zebrafish population dynamics (IBM model). Next, we fitted the DEB model to new experimental data on zebrafish growth and reproduction thus improving existing models. We further analysed the DEB-model and DEB-IBM using a sensitivity analysis. Finally, the predictions of the DEB-IBM were compared to existing observations on natural zebrafish populations and the predicted population dynamics are realistic. While our zebrafish DEB-IBM model can still be improved by acquiring new experimental data on the most uncertain processes (e.g. survival or feeding), it can already serve to predict the impact of compounds at the population level.

Estimating and modeling the cure fraction in population-based cancer survival analysis.

PubMed

Lambert, Paul C; Thompson, John R; Weston, Claire L; Dickman, Paul W

2007-07-01

In population-based cancer studies, cure is said to occur when the mortality (hazard) rate in the diseased group of individuals returns to the same level as that expected in the general population. The cure fraction (the proportion of patients cured of disease) is of interest to patients and is a useful measure to monitor trends in survival of curable disease. There are 2 main types of cure fraction model, the mixture cure fraction model and the non-mixture cure fraction model, with most previous work concentrating on the mixture cure fraction model. In this paper, we extend the parametric non-mixture cure fraction model to incorporate background mortality, thus providing estimates of the cure fraction in population-based cancer studies. We compare the estimates of relative survival and the cure fraction between the 2 types of model and also investigate the importance of modeling the ancillary parameters in the selected parametric distribution for both types of model.

Simulating lifetime outcomes associated with complications for people with type 1 diabetes.

PubMed

Lung, Tom W C; Clarke, Philip M; Hayes, Alison J; Stevens, Richard J; Farmer, Andrew

2013-06-01

The aim of this study was to develop a discrete-time simulation model for people with type 1 diabetes mellitus, to estimate and compare mean life expectancy and quality-adjusted life-years (QALYs) over a lifetime between intensive and conventional blood glucose treatment groups. We synthesized evidence on type 1 diabetes patients using several published sources. The simulation model was based on 13 equations to estimate risks of events and mortality. Cardiovascular disease (CVD) risk was obtained from results of the DCCT (diabetes control and complications trial). Mortality post-CVD event was based on a study using linked administrative data on people with diabetes from Western Australia. Information on incidence of renal disease and the progression to CVD was obtained from studies in Finland and Italy. Lower-extremity amputation (LEA) risk was based on the type 1 diabetes Swedish inpatient registry, and the risk of blindness was obtained from results of a German-based study. Where diabetes-specific data were unavailable, information from other populations was used. We examine the degree and source of parameter uncertainty and illustrate an application of the model in estimating lifetime outcomes of using intensive and conventional treatments for blood glucose control. From 15 years of age, male and female patients had an estimated life expectancy of 47.2 (95 % CI 35.2-59.2) and 52.7 (95 % CI 41.7-63.6) years in the intensive treatment group. The model produced estimates of the lifetime benefits of intensive treatment for blood glucose from the DCCT of 4.0 (95 % CI 1.2-6.8) QALYs for women and 4.6 (95 % CI 2.7-6.9) QALYs for men. Absolute risk per 1,000 person-years for fatal CVD events was simulated to be 1.37 and 2.51 in intensive and conventional treatment groups, respectively. The model incorporates diabetic complications risk data from a type 1 diabetes population and synthesizes other type 1-specific data to estimate long-term outcomes of CVD, end-stage renal

UV lifetime laser demonstrator for space-based applications

NASA Astrophysics Data System (ADS)

Albert, Michael; Puffenburger, Kent; Schum, Tom; Fitzpatrick, Fran; Litvinovitch, Slava; Jones, Darrell; Rudd, Joseph; Hovis, Floyd

2015-09-01

A long-lived UV laser is an enabling technology for a number of high-priority, space-based lidar instruments. These include next generation cloud and aerosol lidars that incorporates a UV channel, direct detection 3-D wind lidars, and ozone DIAL (differential absorption lidar) system. In previous SBIR funded work we developed techniques for increasing the survivability of components in high power UV lasers and demonstrated improved operational lifetimes. In this Phase III ESTO funded effort we are designing and building a TRL (Technology Readiness Level) 6 demonstrator that will have increased output power and a space-qualifiable package that is mechanically robust and thermally-stable. For full space compatibility, thermal control will be through pure conductive cooling. Contamination control processes and optical coatings will be chosen that are compatible with lifetimes in excess of 1 billion shots. The 1064nm output will be frequency tripled to provide greater than 100mJ pulses of 355nm light at 150 Hz. After completing the laser module build in the third quarter of 2015 we will initiate lifetime testing, followed by thermal/vacuum (TVAC) and vibration testing to demonstrate that the design is at TRL 6.

Pulsed food resources, but not forest cover, determine lifetime reproductive success in a forest-dwelling rodent.

PubMed

Hoset, Katrine S; Villers, Alexandre; Wistbacka, Ralf; Selonen, Vesa

2017-09-01

The relative contributions of habitat and food availability on fitness may provide evidence for key habitat features needed to safeguard population persistence. However, defining habitat quality for a species can be a complex task, especially if knowledge on the relationship between individual performance and habitat quality is lacking. Here, we determined the relative importance of the availability of suitable forest habitat, body mass and food from masting tree species on female lifetime reproductive success (LRS) of Siberian flying squirrels (Pteromys volans). We calculated LRS of 500 female flying squirrels based on a 22-year-long longitudinal dataset of two populations from western Finland. We assessed with generalised additive models the potential effects of availability of suitable habitat and cumulative lifetime availability of food from masting tree species on female LRS, longevity and fecundity. On a reduced dataset, we evaluated the importance of female winter body mass and conducted a piecewise path analysis to determine how variables were connected. According to generalised additive models female longevity, fecundity and LRS were mainly determined by variation in cumulative lifetime availability of food from masting alder and birch. Instead, habitat and body mass had a smaller role. The path analysis indicated that lifetime food availability had a direct effect on longevity and fecundity, and these had an equal effect on LRS at both study sites. Our results on LRS show that the occurrence of tree masting events during a female flying squirrel's lifetime has a profoundly larger effect on LRS than the cover of suitable forest habitat. Furthermore, this study emphasises the importance of both fecundity and longevity, and the indirect effects of food availability via those components, as determinants of lifetime fitness in female flying squirrels. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

Landscape-based population viability models demonstrate importance of strategic conservation planning for birds

Treesearch

Thomas W. Bonnot; Frank R. Thompson; Joshua J. Millspaugh; D. Todd Jones-Farland

2013-01-01

Efforts to conserve regional biodiversity in the face of global climate change, habitat loss and fragmentation will depend on approaches that consider population processes at multiple scales. By combining habitat and demographic modeling, landscape-based population viability models effectively relate small-scale habitat and landscape patterns to regional population...

An Individual-Based Model of Zebrafish Population Dynamics Accounting for Energy Dynamics

PubMed Central

Beaudouin, Rémy; Goussen, Benoit; Piccini, Benjamin; Augustine, Starrlight; Devillers, James; Brion, François; Péry, Alexandre R. R.

2015-01-01

Developing population dynamics models for zebrafish is crucial in order to extrapolate from toxicity data measured at the organism level to biological levels relevant to support and enhance ecological risk assessment. To achieve this, a dynamic energy budget for individual zebrafish (DEB model) was coupled to an individual based model of zebrafish population dynamics (IBM model). Next, we fitted the DEB model to new experimental data on zebrafish growth and reproduction thus improving existing models. We further analysed the DEB-model and DEB-IBM using a sensitivity analysis. Finally, the predictions of the DEB-IBM were compared to existing observations on natural zebrafish populations and the predicted population dynamics are realistic. While our zebrafish DEB-IBM model can still be improved by acquiring new experimental data on the most uncertain processes (e.g. survival or feeding), it can already serve to predict the impact of compounds at the population level. PMID:25938409

RDM lifetime measurements in 107Cd

NASA Astrophysics Data System (ADS)

Andgren, K.; Ashley, S. F.; Regan, P. H.; McCutchan, E. A.; Zamfir, N. V.; Amon, L.; Cakirli, R. B.; Casten, R. F.; Clark, R. M.; Gürdal, G.; Keyes, K. L.; Meyer, D. A.; Erduran, M. N.; Papenberg, A.; Pietralla, N.; Plettner, C.; Rainovski, G.; Ribas, R. V.; Thomas, N. J.; Vinson, J.; Warner, D. D.; Werner, V.; Williams, E.

2005-10-01

Lifetimes for decays linking near-yrast states in 107Cd have been measured using the recoil distance method (RDM). The nucleus of interest was populated via the 98Mo(12C,3n)107Cd fusion-evaporation reaction at an incident beam energy of 60 MeV. From the measured lifetimes, transition probabilities have been deduced and compared with the theoretical B(E2) values for limiting cases of harmonic vibrational and axially deformed rotational systems. Our initial results suggest a rotor-like behaviour for the structure based on the unnatural-parity, h11/2 orbital in 107Cd, providing further evidence for the role of this 'shape-polarizing' orbital in stabilizing the nuclear deformation in the A ~ 100 transitional region.

Species abundance distributions in neutral models with immigration or mutation and general lifetimes.

PubMed

Lambert, Amaury

2011-07-01

We consider a general, neutral, dynamical model of biodiversity. Individuals have i.i.d. lifetime durations, which are not necessarily exponentially distributed, and each individual gives birth independently at constant rate λ. Thus, the population size is a homogeneous, binary Crump-Mode-Jagers process (which is not necessarily a Markov process). We assume that types are clonally inherited. We consider two classes of speciation models in this setting. In the immigration model, new individuals of an entirely new species singly enter the population at constant rate μ (e.g., from the mainland into the island). In the mutation model, each individual independently experiences point mutations in its germ line, at constant rate θ. We are interested in the species abundance distribution, i.e., in the numbers, denoted I(n)(k) in the immigration model and A(n)(k) in the mutation model, of species represented by k individuals, k = 1, 2, . . . , n, when there are n individuals in the total population. In the immigration model, we prove that the numbers (I(t)(k); k ≥ 1) of species represented by k individuals at time t, are independent Poisson variables with parameters as in Fisher's log-series. When conditioning on the total size of the population to equal n, this results in species abundance distributions given by Ewens' sampling formula. In particular, I(n)(k) converges as n → ∞ to a Poisson r.v. with mean γ/k, where γ : = μ/λ. In the mutation model, as n → ∞, we obtain the almost sure convergence of n (-1) A(n)(k) to a nonrandom explicit constant. In the case of a critical, linear birth-death process, this constant is given by Fisher's log-series, namely n(-1) A(n)(k) converges to α(k)/k, where α : = λ/(λ + θ). In both models, the abundances of the most abundant species are briefly discussed.

Lifetime distributional effects of Social Security retirement benefits.

PubMed

Smith, Karen; Toder, Eric; Iams, Howard

This article presents three measures of the distribution of actual and projected net benefits (benefits minus payroll taxes) from Social Security's Old-Age and Survivors Insurance (OASI) for people born between 1931 and 1960. The results are based on simulations with the Social Security Administration's Model of Income in the Near Term (MINT), which projects retirement income through 2020. The base sample for MINT is the U.S. Census Bureau's Survey of Income and Program Participation panels for 1990 to 1993, matched with Social Security administrative records. The study population is grouped into 5-year birth cohorts and then ranked by economic status in three ways. First, the population is divided into five groups on the basis of individual lifetime covered earnings, and their lifetime present values of OASI benefits received and payroll taxes paid are calculated. By this measure, OASI provides much higher benefits to the lowest quintile of earners than to other groups, but it becomes less redistributive toward lower earners in more recent birth cohorts. Second, people are ranked by shared lifetime covered earnings, and the values of shared benefits received and payroll taxes paid are computed. Individuals are assumed to split covered earnings, benefits, and payroll taxes with their spouses in the years they are married. By the shared covered earnings measure, OASI is still much more favorable to persons in the lower income quintiles, although to a lesser degree than when people are ranked by individual covered earnings. OASI becomes more progressive among recent cohorts, even as net lifetime benefits decline for the entire population. Finally, individuals are ranked on the basis of their shared permanent income from age 62, when they become eligible for early retirement benefits, until death. Their annual Social Security benefits are compared with the benefits they would have received if they had saved their payroll taxes in individual accounts and used the

Characterization of porcine eyes based on autofluorescence lifetime imaging

NASA Astrophysics Data System (ADS)

Batista, Ana; Breunig, Hans Georg; Uchugonova, Aisada; Morgado, António Miguel; König, Karsten

2015-03-01

Multiphoton microscopy is a non-invasive imaging technique with ideal characteristics for biological applications. In this study, we propose to characterize three major structures of the porcine eye, the cornea, crystalline lens, and retina using two-photon excitation fluorescence lifetime imaging microscopy (2PE-FLIM). Samples were imaged using a laser-scanning microscope, consisting of a broadband sub-15 femtosecond (fs) near-infrared laser. Signal detection was performed using a 16-channel photomultiplier tube (PMT) detector (PML-16PMT). Therefore, spectral analysis of the fluorescence lifetime data was possible. To ensure a correct spectral analysis of the autofluorescence lifetime data, the spectra of the individual endogenous fluorophores were acquired with the 16-channel PMT and with a spectrometer. All experiments were performed within 12h of the porcine eye enucleation. We were able to image the cornea, crystalline lens, and retina at multiple depths. Discrimination of each structure based on their autofluorescence intensity and lifetimes was possible. Furthermore, discrimination between different layers of the same structure was also possible. To the best of our knowledge, this was the first time that 2PE-FLIM was used for porcine lens imaging and layer discrimination. With this study we further demonstrated the feasibility of 2PE-FLIM to image and differentiate three of the main components of the eye and its potential as an ophthalmologic technique.

Fluorescence lifetime imaging microscopy using near-infrared contrast agents.

PubMed

Nothdurft, R; Sarder, P; Bloch, S; Culver, J; Achilefu, S

2012-08-01

Although single-photon fluorescence lifetime imaging microscopy (FLIM) is widely used to image molecular processes using a wide range of excitation wavelengths, the captured emission of this technique is confined to the visible spectrum. Here, we explore the feasibility of utilizing near-infrared (NIR) fluorescent molecular probes with emission >700 nm for FLIM of live cells. The confocal microscope is equipped with a 785 nm laser diode, a red-enhanced photomultiplier tube, and a time-correlated single photon counting card. We demonstrate that our system reports the lifetime distributions of NIR fluorescent dyes, cypate and DTTCI, in cells. In cells labelled separately or jointly with these dyes, NIR FLIM successfully distinguishes their lifetimes, providing a method to sort different cell populations. In addition, lifetime distributions of cells co-incubated with these dyes allow estimate of the dyes' relative concentrations in complex cellular microenvironments. With the heightened interest in fluorescence lifetime-based small animal imaging using NIR fluorophores, this technique further serves as a bridge between in vitro spectroscopic characterization of new fluorophore lifetimes and in vivo tissue imaging. © 2012 The Author Journal of Microscopy © 2012 Royal Microscopical Society.

Association between lifetime exposure to inorganic arsenic in drinking water and coronary heart disease in Colorado residents.

PubMed

James, Katherine A; Byers, Tim; Hokanson, John E; Meliker, Jaymie R; Zerbe, Gary O; Marshall, Julie A

2015-02-01

Chronic diseases, including coronary heart disease (CHD), have been associated with ingestion of drinking water with high levels of inorganic arsenic (> 1,000 μg/L). However, associations have been inconclusive in populations with lower levels (< 100 μg/L) of inorganic arsenic exposure. We conducted a case-cohort study based on individual estimates of lifetime arsenic exposure to examine the relationship between chronic low-level arsenic exposure and risk of CHD. This study included 555 participants with 96 CHD events diagnosed between 1984 and 1998 for which individual lifetime arsenic exposure estimates were determined using data from structured interviews and secondary data sources to determine lifetime residence, which was linked to a geospatial model of arsenic concentrations in drinking water. These lifetime arsenic exposure estimates were correlated with historically collected urinary arsenic concentrations. A Cox proportional-hazards model with time-dependent CHD risk factors was used to assess the association between time-weighted average (TWA) lifetime exposure to low-level inorganic arsenic in drinking water and incident CHD. We estimated a positive association between low-level inorganic arsenic exposure and CHD risk [hazard ratio (HR): = 1.38, 95% CI: 1.09, 1.78] per 15 μg/L while adjusting for age, sex, first-degree family history of CHD, and serum low-density lipoprotein levels. The risk of CHD increased monotonically with increasing TWAs for inorganic arsenic exposure in water relative to < 20 μg/L (HR = 1.2, 95% CI: 0.6, 2.2 for 20-30 μg/L; HR = 2.2; 95% CI: 1.2, 4.0 for 30-45 μg/L; and HR = 3, 95% CI: 1.1, 9.1 for 45-88 μg/L). Lifetime exposure to low-level inorganic arsenic in drinking water was associated with increased risk for CHD in this population.

Population Screening for Hereditary Haemochromatosis in Australia: Construction and Validation of a State-Transition Cost-Effectiveness Model.

PubMed

de Graaff, Barbara; Si, Lei; Neil, Amanda L; Yee, Kwang Chien; Sanderson, Kristy; Gurrin, Lyle C; Palmer, Andrew J

2017-03-01

HFE-associated haemochromatosis, the most common monogenic disorder amongst populations of northern European ancestry, is characterised by iron overload. Excess iron is stored in parenchymal tissues, leading to morbidity and mortality. Population screening programmes are likely to improve early diagnosis, thereby decreasing associated disease. Our aim was to develop and validate a health economics model of screening using utilities and costs from a haemochromatosis cohort. A state-transition model was developed with Markov states based on disease severity. Australian males (aged 30 years) and females (aged 45 years) of northern European ancestry were the target populations. The screening strategy was the status quo approach in Australia; the model was run over a lifetime horizon. Costs were estimated from the government perspective and reported in 2015 Australian dollars ($A); costs and quality-adjusted life-years (QALYs) were discounted at 5% annually. Model validity was assessed using goodness-of-fit analyses. Second-order Monte-Carlo simulation was used to account for uncertainty in multiple parameters. For validity, the model reproduced mortality, life expectancy (LE) and prevalence rates in line with published data. LE for C282Y homozygote males and females were 49.9 and 40.2 years, respectively, slightly lower than population rates. Mean (95% confidence interval) QALYS were 15.7 (7.7-23.7) for males and 14.4 (6.7-22.1) for females. Mean discounted lifetime costs for C282Y homozygotes were $A22,737 (3670-85,793) for males and $A13,840 (1335-67,377) for females. Sensitivity analyses revealed discount rates and prevalence had the greatest impacts on outcomes. We have developed a transparent, validated health economics model of C282Y homozygote haemochromatosis. The model will be useful to decision makers to identify cost-effective screening strategies.

A comparison of linear demographic models and fraction of lifetime egg production for assessing sustainability in sharks.

PubMed

Chapple, Taylor K; Botsford, Louis W

2013-06-01

Conventional methods for management of data-rich fisheries maintain sustainable populations by assuring that lifetime reproduction is adequate for individuals to replace themselves and accounting for density-dependent recruitment. Fishing is not allowed to reduce relative lifetime reproduction, the fraction of current egg production relative to unfished egg production (FLEP), below a sustainable level. Because most shark fisheries are data poor, other representations of persistence status have been used, including linear demographic models, which incorporate life-history characteristics in age-structured models with no density dependence. We tested how well measures of sustainability from 3 linear demographic methods (rebound potential, stochastic growth rate, and potential population increase) reflect actual population persistence by comparing values of these measures with FLEP for 26 shark species. We also calculated the value of fishing mortality (F) that would allow all 26 species to maintain an accepted precautionary threshold for sharks of FLEP = 60%, expressing F as a fraction of natural mortality (M). Values of stochastic growth rate and potential population growth did not covary in rank order with FLEP (p = 0.057 and p = 0.077, respectively) and neither was significantly correlated with FLEP. Ordinal ranking of rebound potential positively covaried with FLEP (p = 0.00013), but the relative rankings of some species were substantially out of order. Adopting a sustainable limit of F = 0.16M would maintain all 26 species above the precautionary minimum value of FLEP (60%). We concluded that shark-fishery and conservation policies should rely on calculation of replacement (i.e., FLEP), and that sharks should be fished at a precautionary level that would protect all stocks (i.e., F< 0.16M). © 2013 Society for Conservation Biology.

Exact Hybrid Particle/Population Simulation of Rule-Based Models of Biochemical Systems

PubMed Central

Stover, Lori J.; Nair, Niketh S.; Faeder, James R.

2014-01-01

Detailed modeling and simulation of biochemical systems is complicated by the problem of combinatorial complexity, an explosion in the number of species and reactions due to myriad protein-protein interactions and post-translational modifications. Rule-based modeling overcomes this problem by representing molecules as structured objects and encoding their interactions as pattern-based rules. This greatly simplifies the process of model specification, avoiding the tedious and error prone task of manually enumerating all species and reactions that can potentially exist in a system. From a simulation perspective, rule-based models can be expanded algorithmically into fully-enumerated reaction networks and simulated using a variety of network-based simulation methods, such as ordinary differential equations or Gillespie's algorithm, provided that the network is not exceedingly large. Alternatively, rule-based models can be simulated directly using particle-based kinetic Monte Carlo methods. This “network-free” approach produces exact stochastic trajectories with a computational cost that is independent of network size. However, memory and run time costs increase with the number of particles, limiting the size of system that can be feasibly simulated. Here, we present a hybrid particle/population simulation method that combines the best attributes of both the network-based and network-free approaches. The method takes as input a rule-based model and a user-specified subset of species to treat as population variables rather than as particles. The model is then transformed by a process of “partial network expansion” into a dynamically equivalent form that can be simulated using a population-adapted network-free simulator. The transformation method has been implemented within the open-source rule-based modeling platform BioNetGen, and resulting hybrid models can be simulated using the particle-based simulator NFsim. Performance tests show that significant memory

Exact hybrid particle/population simulation of rule-based models of biochemical systems.

PubMed

Hogg, Justin S; Harris, Leonard A; Stover, Lori J; Nair, Niketh S; Faeder, James R

2014-04-01

Detailed modeling and simulation of biochemical systems is complicated by the problem of combinatorial complexity, an explosion in the number of species and reactions due to myriad protein-protein interactions and post-translational modifications. Rule-based modeling overcomes this problem by representing molecules as structured objects and encoding their interactions as pattern-based rules. This greatly simplifies the process of model specification, avoiding the tedious and error prone task of manually enumerating all species and reactions that can potentially exist in a system. From a simulation perspective, rule-based models can be expanded algorithmically into fully-enumerated reaction networks and simulated using a variety of network-based simulation methods, such as ordinary differential equations or Gillespie's algorithm, provided that the network is not exceedingly large. Alternatively, rule-based models can be simulated directly using particle-based kinetic Monte Carlo methods. This "network-free" approach produces exact stochastic trajectories with a computational cost that is independent of network size. However, memory and run time costs increase with the number of particles, limiting the size of system that can be feasibly simulated. Here, we present a hybrid particle/population simulation method that combines the best attributes of both the network-based and network-free approaches. The method takes as input a rule-based model and a user-specified subset of species to treat as population variables rather than as particles. The model is then transformed by a process of "partial network expansion" into a dynamically equivalent form that can be simulated using a population-adapted network-free simulator. The transformation method has been implemented within the open-source rule-based modeling platform BioNetGen, and resulting hybrid models can be simulated using the particle-based simulator NFsim. Performance tests show that significant memory savings

Modelling population distribution using remote sensing imagery and location-based data

NASA Astrophysics Data System (ADS)

Song, J.; Prishchepov, A. V.

2017-12-01

Detailed spatial distribution of population density is essential for city studies such as urban planning, environmental pollution and city emergency, even estimate pressure on the environment and human exposure and risks to health. However, most of the researches used census data as the detailed dynamic population distribution are difficult to acquire, especially in microscale research. This research describes a method using remote sensing imagery and location-based data to model population distribution at the function zone level. Firstly, urban functional zones within a city were mapped by high-resolution remote sensing images and POIs. The workflow of functional zones extraction includes five parts: (1) Urban land use classification. (2) Segmenting images in built-up area. (3) Identification of functional segments by POIs. (4) Identification of functional blocks by functional segmentation and weight coefficients. (5) Assessing accuracy by validation points. The result showed as Fig.1. Secondly, we applied ordinary least square and geographically weighted regression to assess spatial nonstationary relationship between light digital number (DN) and population density of sampling points. The two methods were employed to predict the population distribution over the research area. The R²of GWR model were in the order of 0.7 and typically showed significant variations over the region than traditional OLS model. The result showed as Fig.2.Validation with sampling points of population density demonstrated that the result predicted by the GWR model correlated well with light value. The result showed as Fig.3. Results showed: (1) Population density is not linear correlated with light brightness using global model. (2) VIIRS night-time light data could estimate population density integrating functional zones at city level. (3) GWR is a robust model to map population distribution, the adjusted R2 of corresponding GWR models were higher than the optimal OLS models

Modeling the Population Dynamics of Antibiotic-Resistant Bacteria:. AN Agent-Based Approach

NASA Astrophysics Data System (ADS)

Murphy, James T.; Walshe, Ray; Devocelle, Marc

The response of bacterial populations to antibiotic treatment is often a function of a diverse range of interacting factors. In order to develop strategies to minimize the spread of antibiotic resistance in pathogenic bacteria, a sound theoretical understanding of the systems of interactions taking place within a colony must be developed. The agent-based approach to modeling bacterial populations is a useful tool for relating data obtained at the molecular and cellular level with the overall population dynamics. Here we demonstrate an agent-based model, called Micro-Gen, which has been developed to simulate the growth and development of bacterial colonies in culture. The model also incorporates biochemical rules and parameters describing the kinetic interactions of bacterial cells with antibiotic molecules. Simulations were carried out to replicate the development of methicillin-resistant S. aureus (MRSA) colonies growing in the presence of antibiotics. The model was explored to see how the properties of the system emerge from the interactions of the individual bacterial agents in order to achieve a better mechanistic understanding of the population dynamics taking place. Micro-Gen provides a good theoretical framework for investigating the effects of local environmental conditions and cellular properties on the response of bacterial populations to antibiotic exposure in the context of a simulated environment.

Fuzzy Logic-Based Guaranteed Lifetime Protocol for Real-Time Wireless Sensor Networks.

PubMed

Shah, Babar; Iqbal, Farkhund; Abbas, Ali; Kim, Ki-Il

2015-08-18

Few techniques for guaranteeing a network lifetime have been proposed despite its great impact on network management. Moreover, since the existing schemes are mostly dependent on the combination of disparate parameters, they do not provide additional services, such as real-time communications and balanced energy consumption among sensor nodes; thus, the adaptability problems remain unresolved among nodes in wireless sensor networks (WSNs). To solve these problems, we propose a novel fuzzy logic model to provide real-time communication in a guaranteed WSN lifetime. The proposed fuzzy logic controller accepts the input descriptors energy, time and velocity to determine each node's role for the next duration and the next hop relay node for real-time packets. Through the simulation results, we verified that both the guaranteed network's lifetime and real-time delivery are efficiently ensured by the new fuzzy logic model. In more detail, the above-mentioned two performance metrics are improved up to 8%, as compared to our previous work, and 14% compared to existing schemes, respectively.

Model-Based Individualized Treatment of Chemotherapeutics: Bayesian Population Modeling and Dose Optimization

PubMed Central

Jayachandran, Devaraj; Laínez-Aguirre, José; Rundell, Ann; Vik, Terry; Hannemann, Robert; Reklaitis, Gintaras; Ramkrishna, Doraiswami

2015-01-01

6-Mercaptopurine (6-MP) is one of the key drugs in the treatment of many pediatric cancers, auto immune diseases and inflammatory bowel disease. 6-MP is a prodrug, converted to an active metabolite 6-thioguanine nucleotide (6-TGN) through enzymatic reaction involving thiopurine methyltransferase (TPMT). Pharmacogenomic variation observed in the TPMT enzyme produces a significant variation in drug response among the patient population. Despite 6-MP’s widespread use and observed variation in treatment response, efforts at quantitative optimization of dose regimens for individual patients are limited. In addition, research efforts devoted on pharmacogenomics to predict clinical responses are proving far from ideal. In this work, we present a Bayesian population modeling approach to develop a pharmacological model for 6-MP metabolism in humans. In the face of scarcity of data in clinical settings, a global sensitivity analysis based model reduction approach is used to minimize the parameter space. For accurate estimation of sensitive parameters, robust optimal experimental design based on D-optimality criteria was exploited. With the patient-specific model, a model predictive control algorithm is used to optimize the dose scheduling with the objective of maintaining the 6-TGN concentration within its therapeutic window. More importantly, for the first time, we show how the incorporation of information from different levels of biological chain-of response (i.e. gene expression-enzyme phenotype-drug phenotype) plays a critical role in determining the uncertainty in predicting therapeutic target. The model and the control approach can be utilized in the clinical setting to individualize 6-MP dosing based on the patient’s ability to metabolize the drug instead of the traditional standard-dose-for-all approach. PMID:26226448

Residual lifetime and 10 year absolute risks of osteoporotic fractures in Chinese men and women.

PubMed

Si, Lei; Winzenberg, Tania M; Chen, Mingsheng; Jiang, Qicheng; Palmer, Andrew J

2015-06-01

To determine the residual lifetime and 10 year absolute risks of osteoporotic fractures in Chinese men and women. A validated state-transition microsimulation model was used. Microsimulation and probabilistic sensitivity analyses were performed to address the uncertainties in the model. All parameters including fracture incidence rates and mortality rates were retrieved from published literature. Simulated subjects were run through the model until they died to estimate the residual lifetime fracture risks. A 10 year time horizon was used to determine the 10 year fracture risks. We estimated the risk of only the first osteoporotic fracture during the simulation time horizon. The residual lifetime and 10 year risks of having the first osteoporotic (hip, clinical vertebral or wrist) fracture for Chinese women aged 50 years were 40.9% (95% CI: 38.3-44.0%) and 8.2% (95% CI: 6.8-9.3%) respectively. For men, the residual lifetime and 10 year fracture risks were 8.7% (95% CI: 7.5-9.8%) and 1.2% (95% CI: 0.8-1.7%) respectively. The residual lifetime fracture risks declined with age, whilst the 10 year fracture risks increased with age until the short-term mortality risks outstripped the fracture risks. Residual lifetime and 10 year clinical vertebral fracture risks were higher than those of hip and wrist fractures in both sexes. More than one third of the Chinese women and approximately one tenth of the Chinese men aged 50 years are expected to sustain a major osteoporotic fracture in their remaining lifetimes. Due to increased fracture risks and a rapidly ageing population, osteoporosis will present a great challenge to the Chinese healthcare system. While national data was used wherever possible, regional Chinese hip and clinical vertebral fracture incidence rates were used, wrist fracture rates were taken from a Norwegian study and calibrated to the Chinese population. Other fracture sites like tibia, humerus, ribs and pelvis were not included in the analysis, thus these

Coupled modeling of the competitive gettering of transition metals and impact on performance of lifetime sensitive devices

NASA Astrophysics Data System (ADS)

Yazdani, Armin; Chen, Renyu; Dunham, Scott T.

2017-03-01

This work models competitive gettering of metals (Cu, Ni, Fe, Mo, and W) by boron, phosphorus, and dislocation loops, and connects those results directly to device performance. Density functional theory calculations were first performed to determine the binding energies of metals to the gettering sites, and based on that, continuum models were developed to model the redistribution and trapping of the metals. Our models found that Fe is most strongly trapped by the dislocation loops while Cu and Ni are most strongly trapped by the P4V clusters formed in high phosphorus concentrations. In addition, it is found that none of the mentioned gettering sites are effective in gettering Mo and W. The calculated metal redistribution along with the associated capture cross sections and trap energy levels are passed to device simulation via the recombination models to calculate carrier lifetime and the resulting device performance. Thereby, a comprehensive and predictive TCAD framework is developed to optimize the processing conditions to maximize performance of lifetime sensitive devices.

Model of electron lifetimes inside the plasmasphere calculated using a CRRES derived hiss wave amplitude model

NASA Astrophysics Data System (ADS)

Orlova, Ksenia; Spasojevic, Maria; Shprits, Yuri

Particle populations in the inner magnetosphere can change by orders of magnitude on very short time scales. For the last decade observations and theoretical computations showed that resonant interaction of electrons with various plasma waves plays an important role in acceleration and loss mechanisms. Using data from the CRRES plasma wave experiment, we develop quadratic fits to the mean of the wave amplitude squared for plasmaspheric hiss as a function of geomagnetic activity (Kp) and magnetic latitude (lambda) for the dayside (6model is valid for lambda<25(°) , Kp<=6, and for 3lifetimes of electrons are then calculated from the diffusion coefficients. The obtained lifetimes are parameterized as a function of energy, Kp-index, L-shell and can be used in 2D/3D/4D convection and particle tracing codes.

Population based screening for chronic kidney disease: cost effectiveness study.

PubMed

Manns, Braden; Hemmelgarn, Brenda; Tonelli, Marcello; Au, Flora; Chiasson, T Carter; Dong, James; Klarenbach, Scott

2010-11-08

To determine the cost effectiveness of one-off population based screening for chronic kidney disease based on estimated glomerular filtration rate. Cost utility analysis of screening with estimated glomerular filtration rate alone compared with no screening (with allowance for incidental finding of cases of chronic kidney disease). Analyses were stratified by age, diabetes, and the presence or absence of proteinuria. Scenario and sensitivity analyses, including probabilistic sensitivity analysis, were performed. Costs were estimated in all adults and in subgroups defined by age, diabetes, and hypertension. Publicly funded Canadian healthcare system. Large population based laboratory cohort used to estimate mortality rates and incidence of end stage renal disease for patients with chronic kidney disease over a five year follow-up period. Patients had not previously undergone assessment of glomerular filtration rate. Lifetime costs, end stage renal disease, quality adjusted life years (QALYs) gained, and incremental cost per QALY gained. Compared with no screening, population based screening for chronic kidney disease was associated with an incremental cost of $C463 (Canadian dollars in 2009; equivalent to about £275, €308, US $382) and a gain of 0.0044 QALYs per patient overall, representing a cost per QALY gained of $C104 900. In a cohort of 100 000 people, screening for chronic kidney disease would be expected to reduce the number of people who develop end stage renal disease over their lifetime from 675 to 657. In subgroups of people with and without diabetes, the cost per QALY gained was $C22 600 and $C572 000, respectively. In a cohort of 100 000 people with diabetes, screening would be expected to reduce the number of people who develop end stage renal disease over their lifetime from 1796 to 1741. In people without diabetes with and without hypertension, the cost per QALY gained was $C334 000 and $C1 411 100, respectively. Population based

Importance of factors determining the effective lifetime of a mass, long-lasting, insecticidal net distribution: a sensitivity analysis

PubMed Central

2012-01-01

Background Long-lasting insecticidal nets (LLINs) reduce malaria transmission by protecting individuals from infectious bites, and by reducing mosquito survival. In recent years, millions of LLINs have been distributed across sub-Saharan Africa (SSA). Over time, LLINs decay physically and chemically and are destroyed, making repeated interventions necessary to prevent a resurgence of malaria. Because its effects on transmission are important (more so than the effects of individual protection), estimates of the lifetime of mass distribution rounds should be based on the effective length of epidemiological protection. Methods Simulation models, parameterised using available field data, were used to analyse how the distribution's effective lifetime depends on the transmission setting and on LLIN characteristics. Factors considered were the pre-intervention transmission level, initial coverage, net attrition, and both physical and chemical decay. An ensemble of 14 stochastic individual-based model variants for malaria in humans was used, combined with a deterministic model for malaria in mosquitoes. Results The effective lifetime was most sensitive to the pre-intervention transmission level, with a lifetime of almost 10 years at an entomological inoculation rate of two infectious bites per adult per annum (ibpapa), but of little more than 2 years at 256 ibpapa. The LLIN attrition rate and the insecticide decay rate were the next most important parameters. The lifetime was surprisingly insensitive to physical decay parameters, but this could change as physical integrity gains importance with the emergence and spread of pyrethroid resistance. Conclusions The strong dependency of the effective lifetime on the pre-intervention transmission level indicated that the required distribution frequency may vary more with the local entomological situation than with LLIN quality or the characteristics of the distribution system. This highlights the need for malaria monitoring both

Importance of factors determining the effective lifetime of a mass, long-lasting, insecticidal net distribution: a sensitivity analysis.

PubMed

Briët, Olivier J T; Hardy, Diggory; Smith, Thomas A

2012-01-13

Long-lasting insecticidal nets (LLINs) reduce malaria transmission by protecting individuals from infectious bites, and by reducing mosquito survival. In recent years, millions of LLINs have been distributed across sub-Saharan Africa (SSA). Over time, LLINs decay physically and chemically and are destroyed, making repeated interventions necessary to prevent a resurgence of malaria. Because its effects on transmission are important (more so than the effects of individual protection), estimates of the lifetime of mass distribution rounds should be based on the effective length of epidemiological protection. Simulation models, parameterised using available field data, were used to analyse how the distribution's effective lifetime depends on the transmission setting and on LLIN characteristics. Factors considered were the pre-intervention transmission level, initial coverage, net attrition, and both physical and chemical decay. An ensemble of 14 stochastic individual-based model variants for malaria in humans was used, combined with a deterministic model for malaria in mosquitoes. The effective lifetime was most sensitive to the pre-intervention transmission level, with a lifetime of almost 10 years at an entomological inoculation rate of two infectious bites per adult per annum (ibpapa), but of little more than 2 years at 256 ibpapa. The LLIN attrition rate and the insecticide decay rate were the next most important parameters. The lifetime was surprisingly insensitive to physical decay parameters, but this could change as physical integrity gains importance with the emergence and spread of pyrethroid resistance. The strong dependency of the effective lifetime on the pre-intervention transmission level indicated that the required distribution frequency may vary more with the local entomological situation than with LLIN quality or the characteristics of the distribution system. This highlights the need for malaria monitoring both before and during intervention

Metabolic Mapping of Breast Cancer with Multiphoton Spectral and Lifetime Imaging

DTIC Science & Technology

2007-03-01

spectral and lifetime characterization of NADH may be used to reveal metabolic changes in vivo and has potential to be used as an early diagnostic...combined spectral lifetime imaging modality will help for 5 characterization of breast cancer cells from cell culture based models to a relevant in... spectral and lifetime system and integrated into a multiphoton fluorescence excitation microscopy system 7 • Calibrated and characterized this

A statistical regression model for the estimation of acrylamide concentrations in French fries for excess lifetime cancer risk assessment.

PubMed

Chen, Ming-Jen; Hsu, Hui-Tsung; Lin, Cheng-Li; Ju, Wei-Yuan

2012-10-01

Human exposure to acrylamide (AA) through consumption of French fries and other foods has been recognized as a potential health concern. Here, we used a statistical non-linear regression model, based on the two most influential factors, cooking temperature and time, to estimate AA concentrations in French fries. The R(2) of the predictive model is 0.83, suggesting the developed model was significant and valid. Based on French fry intake survey data conducted in this study and eight frying temperature-time schemes which can produce tasty and visually appealing French fries, the Monte Carlo simulation results showed that if AA concentration is higher than 168 ppb, the estimated cancer risk for adolescents aged 13-18 years in Taichung City would be already higher than the target excess lifetime cancer risk (ELCR), and that by taking into account this limited life span only. In order to reduce the cancer risk associated with AA intake, the AA levels in French fries might have to be reduced even further if the epidemiological observations are valid. Our mathematical model can serve as basis for further investigations on ELCR including different life stages and behavior and population groups. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cost-effectiveness of Population Screening for BRCA Mutations in Ashkenazi Jewish Women Compared With Family History–Based Testing

PubMed Central

Manchanda, Ranjit; Legood, Rosa; Burnell, Matthew; McGuire, Alistair; Raikou, Maria; Loggenberg, Kelly; Wardle, Jane; Sanderson, Saskia; Gessler, Sue; Side, Lucy; Balogun, Nyala; Desai, Rakshit; Kumar, Ajith; Dorkins, Huw; Wallis, Yvonne; Chapman, Cyril; Taylor, Rohan; Jacobs, Chris; Tomlinson, Ian; Beller, Uziel; Menon, Usha

2015-01-01

Background: Population-based testing for BRCA1/2 mutations detects the high proportion of carriers not identified by cancer family history (FH)–based testing. We compared the cost-effectiveness of population-based BRCA testing with the standard FH-based approach in Ashkenazi Jewish (AJ) women. Methods: A decision-analytic model was developed to compare lifetime costs and effects amongst AJ women in the UK of BRCA founder-mutation testing amongst: 1) all women in the population age 30 years or older and 2) just those with a strong FH (≥10% mutation risk). The model assumes that BRCA carriers are offered risk-reducing salpingo-oophorectomy and annual MRI/mammography screening or risk-reducing mastectomy. Model probabilities utilize the Genetic Cancer Prediction through Population Screening trial/published literature to estimate total costs, effects in terms of quality-adjusted life-years (QALYs), cancer incidence, incremental cost-effectiveness ratio (ICER), and population impact. Costs are reported at 2010 prices. Costs/outcomes were discounted at 3.5%. We used deterministic/probabilistic sensitivity analysis (PSA) to evaluate model uncertainty. Results: Compared with FH-based testing, population-screening saved 0.090 more life-years and 0.101 more QALYs resulting in 33 days’ gain in life expectancy. Population screening was found to be cost saving with a baseline-discounted ICER of -£2079/QALY. Population-based screening lowered ovarian and breast cancer incidence by 0.34% and 0.62%. Assuming 71% testing uptake, this leads to 276 fewer ovarian and 508 fewer breast cancer cases. Overall, reduction in treatment costs led to a discounted cost savings of £3.7 million. Deterministic sensitivity analysis and 94% of simulations on PSA (threshold £20000) indicated that population screening is cost-effective, compared with current NHS policy. Conclusion: Population-based screening for BRCA mutations is highly cost-effective compared with an FH-based approach in AJ

Interrogation of metabolic and oxygen states of tumors with fiber-based luminescence lifetime spectroscopy.

PubMed

Lukina, Maria; Orlova, Anna; Shirmanova, Marina; Shirokov, Daniil; Pavlikov, Anton; Neubauer, Antje; Studier, Hauke; Becker, Wolfgang; Zagaynova, Elena; Yoshihara, Toshitada; Tobita, Seiji; Shcheslavskiy, Vladislav

2017-02-15

The study of metabolic and oxygen states of cells in a tumor in vivo is crucial for understanding of the mechanisms responsible for tumor development and provides background for the relevant tumor's treatment. Here, we show that a specially designed implantable fiber-optic probe provides a promising tool for optical interrogation of metabolic and oxygen states of a tumor in vivo. In our experiments, the excitation light from a ps diode laser source is delivered to the sample through an exchangeable tip via a multimode fiber, and the emission light is transferred to the detector by another multimode fiber. Fluorescence lifetime of a nicotinamid adenine dinucleotide (NAD(P)H) and phosphorescence lifetime of an oxygen sensor based on an iridium (III) complex of enzothienylpyridine (BTPDM1) are explored both in model experiment in solutions and in living mice.

Socioeconomic status and lifetime risk for workplace eye injury reported by a us population aged 50 years and over.

PubMed

Luo, Huabin; Beckles, Gloria L A; Fang, Xiangming; Crews, John E; Saaddine, Jinan B; Zhang, Xinzhi

2012-04-01

To examine whether socioeconomic status, as measured by educational attainment and annual household income, is associated with lifetime risk for workplace eye injury in a large US population. In analyses of data from the Behavioral Risk Factor Surveillance System (2005-2007, N = 43,510), we used logistic regression analysis and propensity score matching to assess associations between socioeconomic measures and lifetime risk for workplace eye injury among those aged ≥50 years. The lifetime prevalence of self-reported workplace eye injury was significantly higher among men (13.5%) than women (2.6%) (P < 0.001). After adjusting for age, race/ethnicity, eye care insurance, health status, and risk-taking behaviors, men with less than high school education (adjusted odds ratio [OR] = 2.24, 95% CI: 1.74-2.87) or high school education (adjusted OR = 1.92, 95% CI: 1.57-2.33) were more likely to report having had a lifetime workplace eye injury than those with more than a high school education. Men with an annual household income <$15,000 were also more likely to report having had a lifetime workplace eye injury than those whose income was >$50,000 (adjusted OR = 1.44, 95% CI: 1.07-1.95). After adjusting for other factors, no statistically significant associations between education, income, and lifetime workplace eye injury were found among women. Socioeconomic status was associated with lifetime risk for workplace eye injury among men but not women. Greater public awareness of individual and societal impacts of workplace eye injuries, especially among socioeconomically disadvantaged men, could help support efforts to develop a coordinated prevention strategy to minimize avoidable workplace eye injuries.

Beyond R 0: Demographic Models for Variability of Lifetime Reproductive Output

PubMed Central

Caswell, Hal

2011-01-01

The net reproductive rate measures the expected lifetime reproductive output of an individual, and plays an important role in demography, ecology, evolution, and epidemiology. Well-established methods exist to calculate it from age- or stage-classified demographic data. As an expectation, provides no information on variability; empirical measurements of lifetime reproduction universally show high levels of variability, and often positive skewness among individuals. This is often interpreted as evidence of heterogeneity, and thus of an opportunity for natural selection. However, variability provides evidence of heterogeneity only if it exceeds the level of variability to be expected in a cohort of identical individuals all experiencing the same vital rates. Such comparisons require a way to calculate the statistics of lifetime reproduction from demographic data. Here, a new approach is presented, using the theory of Markov chains with rewards, obtaining all the moments of the distribution of lifetime reproduction. The approach applies to age- or stage-classified models, to constant, periodic, or stochastic environments, and to any kind of reproductive schedule. As examples, I analyze data from six empirical studies, of a variety of animal and plant taxa (nematodes, polychaetes, humans, and several species of perennial plants). PMID:21738586

STK/Lifetime as a Replacement for Heritage Orbital Lifetime Software

NASA Technical Reports Server (NTRS)

Dove, Edwin

2004-01-01

The Flight Dynamics Analysis Branch (FDAB) of NASNGSFC is tasked with determining the orbital lifetime of several developmental and operational satellites, which include the Hubble Space Telescope. A DOS based program developed by the FDAB many years ago, called PC Lifetime, is used to determine a satellite s lifetime and could soon be in need of a replacement. STK s Lifetime Object Tool is a possible candidate. Due to the reduced support of the PC Lifetime program, and the growing incompatibility of older programs with new operating systems, a comparative analysis was done to determine if STWLifetime could meet the stringent requirements that were laid before it. The use of highly accurate numerical propagators such as STK s High Precision Orbit Propagator ( OP) and the Goddard Trajectory Determination System (GTDS) provided a basis on which to compare STWLifetime s results. Several test cases were run, but the main four test cases would determine whether or not STWLifetime could be PC- Lifetime s replacement. These four cases include a geotransfer orbit, two circular LEOS, and a Poiar LEO. Following rigorous testmg procedures, a conclusion will be determined. STK has proved to be a versatile program on many satellite missions and the FDAB has high hopes that it can pass FDAB s requirements for orbital lifetime prediction.

Fuzzy Logic-Based Guaranteed Lifetime Protocol for Real-Time Wireless Sensor Networks

PubMed Central

Shah, Babar; Iqbal, Farkhund; Abbas, Ali; Kim, Ki-Il

2015-01-01

Few techniques for guaranteeing a network lifetime have been proposed despite its great impact on network management. Moreover, since the existing schemes are mostly dependent on the combination of disparate parameters, they do not provide additional services, such as real-time communications and balanced energy consumption among sensor nodes; thus, the adaptability problems remain unresolved among nodes in wireless sensor networks (WSNs). To solve these problems, we propose a novel fuzzy logic model to provide real-time communication in a guaranteed WSN lifetime. The proposed fuzzy logic controller accepts the input descriptors energy, time and velocity to determine each node’s role for the next duration and the next hop relay node for real-time packets. Through the simulation results, we verified that both the guaranteed network’s lifetime and real-time delivery are efficiently ensured by the new fuzzy logic model. In more detail, the above-mentioned two performance metrics are improved up to 8%, as compared to our previous work, and 14% compared to existing schemes, respectively. PMID:26295238

DC-Obesity: A New Model for Estimating Differential Lifetime Costs of Overweight and Obesity by Socioeconomic Status.

PubMed

Sonntag, Diana; Jarczok, Marc N; Ali, Shehzad

2017-09-01

The aim of this study was to quantify the magnitude of lifetime costs of overweight and obesity by socioeconomic status (SES). Differential Costs (DC)-Obesity is a new model that uses time-to-event simulation and the Markov modeling approach to compare lifetime excess costs of overweight and obesity among individuals with low, middle, and high SES. SES was measured by a multidimensional aggregated index based on level of education, occupational class, and income by using longitudinal data of the German Socioeconomic Panel (SOEP). Random-effects meta-analysis was applied to combine estimates of (in)direct costs of overweight and obesity. DC-Obesity brings attention to opposite socioeconomic gradients in lifetime costs due to obesity compared to overweight. Compared to individuals with obesity and high SES, individuals with obesity and low SES had lifetime excess costs that were two times higher (€8,526). In contrast, these costs were 20% higher in groups with overweight and high SES than in groups with overweight and low SES (€2,711). The results of this study indicate that SES may play a pivotal role in designing cost-effective and sustainable interventions to prevent and treat overweight and obesity. DC-Obesity may help public policy planners to make informed decisions about obesity programs targeted at vulnerable SES groups. © 2017 The Obesity Society.

An example of population-level risk assessments for small mammals using individual-based population models.

PubMed

Schmitt, Walter; Auteri, Domenica; Bastiansen, Finn; Ebeling, Markus; Liu, Chun; Luttik, Robert; Mastitsky, Sergey; Nacci, Diane; Topping, Chris; Wang, Magnus

2016-01-01

This article presents a case study demonstrating the application of 3 individual-based, spatially explicit population models (IBMs, also known as agent-based models) in ecological risk assessments to predict long-term effects of a pesticide to populations of small mammals. The 3 IBMs each used a hypothetical fungicide (FungicideX) in different scenarios: spraying in cereals (common vole, Microtus arvalis), spraying in orchards (field vole, Microtus agrestis), and cereal seed treatment (wood mouse, Apodemus sylvaticus). Each scenario used existing model landscapes, which differed greatly in size and structural complexity. The toxicological profile of FungicideX was defined so that the deterministic long-term first tier risk assessment would result in high risk to small mammals, thus providing the opportunity to use the IBMs for risk assessment refinement (i.e., higher tier risk assessment). Despite differing internal model design and scenarios, results indicated in all 3 cases low population sensitivity unless FungicideX was applied at very high (×10) rates. Recovery from local population impacts was generally fast. Only when patch extinctions occured in simulations of intentionally high acute toxic effects, recovery periods, then determined by recolonization, were of any concern. Conclusions include recommendations for the most important input considerations, including the selection of exposure levels, duration of simulations, statistically robust number of replicates, and endpoints to report. However, further investigation and agreement are needed to develop recommendations for landscape attributes such as size, structure, and crop rotation to define appropriate regulatory risk assessment scenarios. Overall, the application of IBMs provides multiple advantages to higher tier ecological risk assessments for small mammals, including consistent and transparent direct links to specific protection goals, and the consideration of more realistic scenarios. © 2015 SETAC.

Population Group Abortion Rates and Lifetime Incidence of Abortion: United States, 2008-2014.

PubMed

Jones, Rachel K; Jerman, Jenna

2017-12-01

To assess the prevalence of abortion among population groups and changes in rates between 2008 and 2014. We used secondary data from the Abortion Patient Survey, the American Community Survey, and the National Survey of Family Growth to estimate abortion rates. We used information from the Abortion Patient Survey to estimate the lifetime incidence of abortion. Between 2008 and 2014, the abortion rate declined 25%, from 19.4 to 14.6 per 1000 women aged 15 to 44 years. The abortion rate for adolescents aged 15 to 19 years declined 46%, the largest of any group. Abortion rates declined for all racial and ethnic groups but were larger for non-White women than for non-Hispanic White women. Although the abortion rate decreased 26% for women with incomes less than 100% of the federal poverty level, this population had the highest abortion rate of all the groups examined: 36.6. If the 2014 age-specific abortion rates prevail, 24% of women aged 15 to 44 years in that year will have an abortion by age 45 years. The decline in abortion was not uniform across all population groups.

The lifetime cost of spinal cord injury in Ontario, Canada: A population-based study from the perspective of the public health care payer.

PubMed

Chan, Brian Chun-Fai; Cadarette, Suzanne M; Wodchis, Walter P; Krahn, Murray D; Mittmann, Nicole

2018-06-20

To determine the publicly funded health care system lifetime cost-of-illness of spinal cord injury (SCI) from the perspective of the Ontario Ministry of Health and Long-term Care. Individuals hospitalized for their first SCI between the years 2005 and 2011 were identified and their health care costs were calculated using Ontario administrative health care data. From this information, lifetime costs were estimated using phase-based costing methods. The spinal cord injured cohort was matched to a non-spinal cord injured using propensity score matching. Net costs were determined by calculating the difference in costs between the two matched groups. Net costs were also presented for subgroups stratified by demographic characteristics. A total of 1,716 individuals with SCI were identified and matched in our study. The net lifetime cost of SCI was $336,000 per person. Much of the costs were observed in the first year post-SCI. The lifetime cost of SCI for individuals with a concurrent pressure ulcer at the initial hospitalization rises to $479,600. Costs were also higher for individuals with cervical or thoracic injury or requiring inpatient rehabilitation. Spinal cord injury is a substantial burden to the health care system. Our results are limited to the direct health care costs from the publicly funded health care payer perspective. Further analysis with a broader perspective is needed to understand the full economic impact of this catastrophic condition.

An isochrone data base and a rapid model for stellar population synthesis

NASA Astrophysics Data System (ADS)

Li, Zhongmu; Han, Zhanwen

2008-06-01

We first presented an isochrone data base that can be widely used for stellar population synthesis studies and colour-magnitude diagram (CMD) fitting. The data base consists of the isochrones of both single-star and binary-star simple stellar populations (ss-SSPs and bs-SSPs). The ranges for the age and metallicity of populations are 0-15 Gyr and 0.0001-0.03, respectively. All data are available for populations with two widely used initial mass functions (IMFs), that is, Salpeter IMF and Chabrier IMF. The uncertainty caused by the data base (about 0.81 per cent) is designed to be smaller than those caused by the Hurley code and widely used stellar spectra libraries (e.g. BaSeL 3.1) when it is used for stellar population synthesis. Based on the isochrone data base, we then built a rapid stellar population synthesis (RPS) model and calculated the high-resolution (0.3-Å) integrated spectral energy distributions, Lick indices and colour indices for bs-SSPs and ss-SSPs. In particular, we calculated the UBVRIJHKLM colours, ugriz colours and some composite colours that consist of magnitudes on different systems. These colours are useful for disentangling the well-known stellar age-metallicity degeneracy according to our previous work. As an example for applying the isochrone data base for CMD fitting, we fitted the CMDs of two star clusters (M67 and NGC1868) and obtained their distance moduli, colour excesses, stellar metallicities and ages. The results showed that the isochrones of bs-SSPs are closer to those of real star clusters. It suggests that we should take the effects of binary interactions into account in stellar population synthesis. We also discussed on the limitations of the application of the isochrone data base and the results of the RPS model. All the data are available at the CDS or on request to the authors. E-mail: zhongmu.li@gmail.com

Spatial structures in a simple model of population dynamics for parasite-host interactions

NASA Astrophysics Data System (ADS)

Dong, J. J.; Skinner, B.; Breecher, N.; Schmittmann, B.; Zia, R. K. P.

2015-08-01

Spatial patterning can be crucially important for understanding the behavior of interacting populations. Here we investigate a simple model of parasite and host populations in which parasites are random walkers that must come into contact with a host in order to reproduce. We focus on the spatial arrangement of parasites around a single host, and we derive using analytics and numerical simulations the necessary conditions placed on the parasite fecundity and lifetime for the population's long-term survival. We also show that the parasite population can be pushed to extinction by a large drift velocity, but, counterintuitively, a small drift velocity generally increases the parasite population.

Likelihood inference for COM-Poisson cure rate model with interval-censored data and Weibull lifetimes.

PubMed

Pal, Suvra; Balakrishnan, N

2017-10-01

In this paper, we consider a competing cause scenario and assume the number of competing causes to follow a Conway-Maxwell Poisson distribution which can capture both over and under dispersion that is usually encountered in discrete data. Assuming the population of interest having a component cure and the form of the data to be interval censored, as opposed to the usually considered right-censored data, the main contribution is in developing the steps of the expectation maximization algorithm for the determination of the maximum likelihood estimates of the model parameters of the flexible Conway-Maxwell Poisson cure rate model with Weibull lifetimes. An extensive Monte Carlo simulation study is carried out to demonstrate the performance of the proposed estimation method. Model discrimination within the Conway-Maxwell Poisson distribution is addressed using the likelihood ratio test and information-based criteria to select a suitable competing cause distribution that provides the best fit to the data. A simulation study is also carried out to demonstrate the loss in efficiency when selecting an improper competing cause distribution which justifies the use of a flexible family of distributions for the number of competing causes. Finally, the proposed methodology and the flexibility of the Conway-Maxwell Poisson distribution are illustrated with two known data sets from the literature: smoking cessation data and breast cosmesis data.

Religiosity and Risky Sexual Behaviors among an African American Church-based Population

PubMed Central

Hawes, Starlyn M.; Berkley-Patton, Jannette Y.

2014-01-01

African Americans are disproportionately burdened by STDs and HIV in the US. This study examined the relationships between demographics, religiosity, and sexual risk behaviors among 255 adult African American church-based participants. Although participants were highly religious, they reported an average of seven lifetime sex partners and most inconsistently used condoms. Several demographic variables and religiosity significantly predicted lifetime HIV-related risk factors. Taken together, findings indicated that this population is at risk for HIV. Future research should continue to identify correlates of risky sexual behavior among African American parishioners to facilitate the development of HIV risk reduction interventions in their church settings. PMID:23054481

Studies on Mathematical Models of Wet Adhesion and Lifetime Prediction of Organic Coating/Steel by Grey System Theory.

PubMed

Meng, Fandi; Liu, Ying; Liu, Li; Li, Ying; Wang, Fuhui

2017-06-28

A rapid degradation of wet adhesion is the key factor controlling coating lifetime, for the organic coatings under marine hydrostatic pressure. The mathematical models of wet adhesion have been studied by Grey System Theory (GST). Grey models (GM) (1, 1) of epoxy varnish (EV) coating/steel and epoxy glass flake (EGF) coating/steel have been established, and a lifetime prediction formula has been proposed on the basis of these models. The precision assessments indicate that the established models are accurate, and the prediction formula is capable of making precise lifetime forecasting of the coatings.

FPGA-based multi-channel fluorescence lifetime analysis of Fourier multiplexed frequency-sweeping lifetime imaging

PubMed Central

Zhao, Ming; Li, Yu; Peng, Leilei

2014-01-01

We report a fast non-iterative lifetime data analysis method for the Fourier multiplexed frequency-sweeping confocal FLIM (Fm-FLIM) system [ Opt. Express22, 10221 ( 2014)24921725]. The new method, named R-method, allows fast multi-channel lifetime image analysis in the system’s FPGA data processing board. Experimental tests proved that the performance of the R-method is equivalent to that of single-exponential iterative fitting, and its sensitivity is well suited for time-lapse FLIM-FRET imaging of live cells, for example cyclic adenosine monophosphate (cAMP) level imaging with GFP-Epac-mCherry sensors. With the R-method and its FPGA implementation, multi-channel lifetime images can now be generated in real time on the multi-channel frequency-sweeping FLIM system, and live readout of FRET sensors can be performed during time-lapse imaging. PMID:25321778

Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico.

PubMed

Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

2015-09-30

Determining ionizing radiation in a geographic area serves to assess its effects on a population's health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h(-1). At the same sites, 48 soil samples were taken to obtain the activity concentrations of (226)Ra, (232)Th and (40)K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h(-1). Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg(-1), for (226)Ra, (232)Th and (40)K, respectively. From the analysis, the spatial distribution of (232)Th, (226)Ra and (40)K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize.

Cross-shell excitations from the f p shell: Lifetime measurements in 61Zn

NASA Astrophysics Data System (ADS)

Queiser, M.; Vogt, A.; Seidlitz, M.; Reiter, P.; Togashi, T.; Shimizu, N.; Utsuno, Y.; Otsuka, T.; Honma, M.; Petkov, P.; Arnswald, K.; Altenkirch, R.; Birkenbach, B.; Blazhev, A.; Braunroth, T.; Dewald, A.; Eberth, J.; Fransen, C.; Fu, B.; Hess, H.; Hetzenegger, R.; Hirsch, R.; Jolie, J.; Karayonchev, V.; Kaya, L.; Lewandowski, L.; Müller-Gatermann, C.; Régis, J.-M.; Rosiak, D.; Schneiders, D.; Siebeck, B.; Steinbach, T.; Wolf, K.; Zell, K.-O.

2017-10-01

Lifetimes of excited states in the neutron-deficient nucleus 61Zn were measured employing the recoil-distance Doppler-shift (RDDS) and the electronic fast-timing methods at the University of Cologne. The nucleus of interest was populated as an evaporation residue in 40Ca(24Mg,n 2 p )61Zn and 58Ni(α ,n )61Zn reactions at 67 and 19 MeV, respectively. Five lifetimes were measured for the first time, including the lifetime of the 5 /21- isomer at 124 keV. Short lifetimes from the RDDS analysis are corrected for Doppler-shift attenuation (DSA) in the target and stopper foils. Ambiguous observations in previous measurements were resolved. The obtained lifetimes are compared to predictions from different sets of shell-model calculations in the f p , f5 /2p g9 /2 , and multishell f p -g9 /2d5 /2 model spaces. The band built on the 9 /21+ state exhibits a prolate deformation with β ≈0.24 . Especially, the inclusion of cross-shell excitation into the 1 d5 /2 orbital is found to be decisive for the description of collectivity in the first excited positive-parity band.

Lifetime and 5 years risk of breast cancer and attributable risk factor according to Gail model in Iranian women

PubMed Central

Mohammadbeigi, Abolfazl; Mohammadsalehi, Narges; Valizadeh, Razieh; Momtaheni, Zeinab; Mokhtari, Mohsen; Ansari, Hossein

2015-01-01

Introduction: Breast cancer is the most commonly diagnosed cancers in women worldwide and in Iran. It is expected to account for 29% of all new cancers in women at 2015. This study aimed to assess the 5 years and lifetime risk of breast cancer according to Gail model, and to evaluate the effect of other additional risk factors on the Gail risk. Materials and Methods: A cross sectional study conducted on 296 women aged more than 34-year-old in Qom, Center of Iran. Breast Cancer Risk Assessment Tool calculated the Gail risk for each subject. Data were analyzed by paired t-test, independent t-test, and analysis of variance in bivariate approach to evaluate the effect of each factor on Gail risk. Multiple linear regression models with stepwise method were used to predict the effect of each variable on the Gail risk. Results: The mean age of the participants was 47.8 ± 8.8-year-old and 47% have Fars ethnicity. The 5 years and lifetime risk was 0.37 ± 0.18 and 4.48 ± 0.925%, respectively. It was lower than the average risk in same race and age women (P < 0.001). Being single, positive family history of breast cancer, positive history of biopsy, and radiotherapy as well as using nonhormonal contraceptives were related to higher lifetime risk (P < 0.05). Moreover, a significant direct correlation observed between lifetime risk and body mass index, age of first live birth, and menarche age. While an inversely correlation observed between lifetimes risk of breast cancer and total month of breast feeding duration and age. Conclusion: Based on our results, the 5 years and lifetime risk of breast cancer according to Gail model was lower than the same race and age. Moreover, by comparison with national epidemiologic indicators about morbidity and mortality of breast cancer, it seems that the Gail model overestimate the risk of breast cancer in Iranian women. PMID:26229355

POPULATION-BASED EXPOSURE MODELING FOR AIR POLLUTANTS AT EPA'S NATIONAL EXPOSURE RESEARCH LABORATORY

EPA Science Inventory

The US EPA's National Exposure Research Laboratory (NERL) has been developing, applying, and evaluating population-based exposure models to improve our understanding of the variability in personal exposure to air pollutants. Estimates of population variability are needed for E...

Preconception stress and the secondary sex ratio in a population-based preconception cohort.

PubMed

Bae, Jisuk; Lynch, Courtney D; Kim, Sungduk; Sundaram, Rajeshwari; Sapra, Katherine J; Buck Louis, Germaine M

2017-03-01

To examine the association between preconception parental stress and the secondary sex ratio, defined as the ratio of males to females at birth. A population-based preconception cohort. Not applicable. A total of 235 couples who were enrolled before conception in Michigan and Texas between 2005 and 2009 and who had a singleton birth during the follow-up period. Couples were interviewed separately at baseline to obtain information on perceived stress (Cohen's Perceived Stress Scale) and lifetime history of physician-diagnosed anxiety and/or mood disorders. Female partners were also trained to collect basal saliva samples for the measurement of salivary stress markers, alpha-amylase and cortisol. None. Birth outcome data including infant sex were collected upon delivery. Modified Poisson regression models were used to estimate the relative risks (RRs) of a male birth for each stress marker. After adjusting for potential confounders, we observed a 76% increase in the risk of fathering a male infant (RR 1.76; 95% confidence interval 1.17-2.65) in men diagnosed with anxiety disorders compared with those who were not diagnosed. When lifetime history of physician-diagnosed anxiety disorders was modeled jointly for the couple, the association was slightly strengthened (RR 2.03; 95% confidence interval 1.46-2.84). This prospective cohort study suggests that paternal lifetime history of physician-diagnosed anxiety disorders may be associated with an increase in the secondary sex ratio, resulting in an excess of male births. Copyright © 2016 American Society for Reproductive Medicine. All rights reserved.

Methods for estimating population density in data-limited areas: evaluating regression and tree-based models in Peru.

PubMed

Anderson, Weston; Guikema, Seth; Zaitchik, Ben; Pan, William

2014-01-01

Obtaining accurate small area estimates of population is essential for policy and health planning but is often difficult in countries with limited data. In lieu of available population data, small area estimate models draw information from previous time periods or from similar areas. This study focuses on model-based methods for estimating population when no direct samples are available in the area of interest. To explore the efficacy of tree-based models for estimating population density, we compare six different model structures including Random Forest and Bayesian Additive Regression Trees. Results demonstrate that without information from prior time periods, non-parametric tree-based models produced more accurate predictions than did conventional regression methods. Improving estimates of population density in non-sampled areas is important for regions with incomplete census data and has implications for economic, health and development policies.

Methods for Estimating Population Density in Data-Limited Areas: Evaluating Regression and Tree-Based Models in Peru

PubMed Central

Anderson, Weston; Guikema, Seth; Zaitchik, Ben; Pan, William

2014-01-01

Obtaining accurate small area estimates of population is essential for policy and health planning but is often difficult in countries with limited data. In lieu of available population data, small area estimate models draw information from previous time periods or from similar areas. This study focuses on model-based methods for estimating population when no direct samples are available in the area of interest. To explore the efficacy of tree-based models for estimating population density, we compare six different model structures including Random Forest and Bayesian Additive Regression Trees. Results demonstrate that without information from prior time periods, non-parametric tree-based models produced more accurate predictions than did conventional regression methods. Improving estimates of population density in non-sampled areas is important for regions with incomplete census data and has implications for economic, health and development policies. PMID:24992657

Studies on Mathematical Models of Wet Adhesion and Lifetime Prediction of Organic Coating/Steel by Grey System Theory

PubMed Central

Meng, Fandi; Liu, Ying; Liu, Li; Li, Ying; Wang, Fuhui

2017-01-01

A rapid degradation of wet adhesion is the key factor controlling coating lifetime, for the organic coatings under marine hydrostatic pressure. The mathematical models of wet adhesion have been studied by Grey System Theory (GST). Grey models (GM) (1, 1) of epoxy varnish (EV) coating/steel and epoxy glass flake (EGF) coating/steel have been established, and a lifetime prediction formula has been proposed on the basis of these models. The precision assessments indicate that the established models are accurate, and the prediction formula is capable of making precise lifetime forecasting of the coatings. PMID:28773073

Lifetime and 12-month prevalence of eating disorders amongst women in mid-life: a population-based study of diagnoses and risk factors.

PubMed

Micali, Nadia; Martini, Maria G; Thomas, Jennifer J; Eddy, Kamryn T; Kothari, Radha; Russell, Ellie; Bulik, Cynthia M; Treasure, Janet

2017-01-17

Eating disorders (EDs) are common amongst women; however, no research has specifically investigated the lifetime/12-month prevalence of eating disorders amongst women in mid-life (i.e., fourth and fifth decade of life) and the relevant longitudinal risk factors. We aimed to investigate the lifetime and 12-month prevalence of EDs and lifetime health service use and to identify childhood, parenting, and personality risk factors. This is a two-phase prevalence study, nested within an existing longitudinal community-based sample of women in mid-life. A total of 5658 women from the UK Avon Longitudinal Study of Parents and Children (ALSPAC; enrolled 20 years earlier) participated. ED diagnoses were obtained using validated structured interviews. Weighted analyses were carried out accounting for the two-phase methodology to obtain prevalence figures and to carry out risk factor regression analyses. By mid-life, 15.3% (95% confidence intervals, 13.5-17.4%) of women had met criteria for a lifetime ED. The 12-month prevalence of EDs was 3.6%. Childhood sexual abuse was prospectively associated with all binge/purge type disorders and an external locus of control was associated with binge-eating disorder. Better maternal care was protective for bulimia nervosa. Childhood life events and interpersonal sensitivity were associated with all EDs. By mid-life a significant proportion of women will experience an ED, and few women accessed healthcare. Active EDs are common in mid-life, both due to new onset and chronic disorders. Increased awareness of the full spectrum of EDs in this stage of life and adequate service provision is important. This is the first study to investigate childhood and personality risk factors for full threshold and sub-threshold EDs and to identify common predictors for full and sub-threshold EDs. Further research should clarify the role of preventable risk factors on both full and sub-threshold EDs.

The dynamic influence of human resources on evidence-based intervention sustainability and population outcomes: an agent-based modeling approach.

PubMed

McKay, Virginia R; Hoffer, Lee D; Combs, Todd B; Margaret Dolcini, M

2018-06-05

Sustaining evidence-based interventions (EBIs) is an ongoing challenge for dissemination and implementation science in public health and social services. Characterizing the relationship among human resource capacity within an agency and subsequent population outcomes is an important step to improving our understanding of how EBIs are sustained. Although human resource capacity and population outcomes are theoretically related, examining them over time within real-world experiments is difficult. Simulation approaches, especially agent-based models, offer advantages that complement existing methods. We used an agent-based model to examine the relationships among human resources, EBI delivery, and population outcomes by simulating provision of an EBI through a hypothetical agency and its staff. We used data from existing studies examining a widely implemented HIV prevention intervention to inform simulation design, calibration, and validity. Once we developed a baseline model, we used the model as a simulated laboratory by systematically varying three human resource variables: the number of staff positions, the staff turnover rate, and timing in training. We tracked the subsequent influence on EBI delivery and the level of population risk over time to describe the overall and dynamic relationships among these variables. Higher overall levels of human resource capacity at an agency (more positions) led to more extensive EBI delivery over time and lowered population risk earlier in time. In simulations representing the typical human resource investments, substantial influences on population risk were visible after approximately 2 years and peaked around 4 years. Human resources, especially staff positions, have an important impact on EBI sustainability and ultimately population health. A minimum level of human resources based on the context (e.g., size of the initial population and characteristics of the EBI) is likely needed for an EBI to have a meaningful impact on

[Prediction of schistosomiasis infection rates of population based on ARIMA-NARNN model].

PubMed

Ke-Wei, Wang; Yu, Wu; Jin-Ping, Li; Yu-Yu, Jiang

2016-07-12

To explore the effect of the autoregressive integrated moving average model-nonlinear auto-regressive neural network (ARIMA-NARNN) model on predicting schistosomiasis infection rates of population. The ARIMA model, NARNN model and ARIMA-NARNN model were established based on monthly schistosomiasis infection rates from January 2005 to February 2015 in Jiangsu Province, China. The fitting and prediction performances of the three models were compared. Compared to the ARIMA model and NARNN model, the mean square error (MSE), mean absolute error (MAE) and mean absolute percentage error (MAPE) of the ARIMA-NARNN model were the least with the values of 0.011 1, 0.090 0 and 0.282 4, respectively. The ARIMA-NARNN model could effectively fit and predict schistosomiasis infection rates of population, which might have a great application value for the prevention and control of schistosomiasis.

Lifetimes of excited states in 196, 198Pt; Application of interacting boson approximation model to even Pt isotopes systematics

NASA Astrophysics Data System (ADS)

Bolotin, H. H.; Stuchbery, A. E.; Morrison, I.; Kennedy, D. L.; Ryan, C. G.; Sie, S. H.

1981-11-01

The lifetimes and lifetime limits of the low-lying excited states up to and including the 6 1+ levels in 196, 198Pt were determined by the recoil-distance method (RDM). Gamma-ray angular distributions in 198Pt were also measured. These states were populated by multiple Coulomb excitation using 220 MeV 58Ni ion beams and the measurements were carried out in coincidence with back-scattered projectiles. The measured mean lives of the states and B(E2) values inferred for the transitions between levels are presented. These specific findings, and the observed structure systematics obtained from the combination of the present results and those of prior workers for the even 194-198Pt isotopes, are critically compared with our structure calculations employing the interacting boson approximation (IBA) model incorporating a symmetry-breaking quadrupole force; evaluative comparisons are also made with boson expansion theory (BET) calculations.

Monte Carlo mixture model of lifetime cancer incidence risk from radiation exposure on shuttle and international space station

NASA Technical Reports Server (NTRS)

Peterson, L. E.; Cucinotta, F. A.; Wilson, J. W. (Principal Investigator)

1999-01-01

Estimating uncertainty in lifetime cancer risk for human exposure to space radiation is a unique challenge. Conventional risk assessment with low-linear-energy-transfer (LET)-based risk from Japanese atomic bomb survivor studies may be inappropriate for relativistic protons and nuclei in space due to track structure effects. This paper develops a Monte Carlo mixture model (MCMM) for transferring additive, National Institutes of Health multiplicative, and multiplicative excess cancer incidence risks based on Japanese atomic bomb survivor data to determine excess incidence risk for various US astronaut exposure profiles. The MCMM serves as an anchor point for future risk projection methods involving biophysical models of DNA damage from space radiation. Lifetime incidence risks of radiation-induced cancer for the MCMM based on low-LET Japanese data for nonleukemia (all cancers except leukemia) were 2.77 (90% confidence limit, 0.75-11.34) for males exposed to 1 Sv at age 45 and 2.20 (90% confidence limit, 0.59-10.12) for males exposed at age 55. For females, mixture model risks for nonleukemia exposed separately to 1 Sv at ages of 45 and 55 were 2.98 (90% confidence limit, 0.90-11.70) and 2.44 (90% confidence limit, 0.70-10.30), respectively. Risks for high-LET 200 MeV protons (LET=0.45 keV/micrometer), 1 MeV alpha-particles (LET=100 keV/micrometer), and 600 MeV iron particles (LET=180 keV/micrometer) were scored on a per particle basis by determining the particle fluence required for an average of one particle per cell nucleus of area 100 micrometer(2). Lifetime risk per proton was 2.68x10(-2)% (90% confidence limit, 0.79x10(-3)%-0. 514x10(-2)%). For alpha-particles, lifetime risk was 14.2% (90% confidence limit, 2.5%-31.2%). Conversely, lifetime risk per iron particle was 23.7% (90% confidence limit, 4.5%-53.0%). Uncertainty in the DDREF for high-LET particles may be less than that for low-LET radiation because typically there is very little dose-rate dependence

Rainflow Algorithm-Based Lifetime Estimation of Power Semiconductors in Utility Applications

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

GopiReddy, Lakshmi Reddy; Tolbert, Leon M.; Ozpineci, Burak

Rainflow algorithms are one of the popular counting methods used in fatigue and failure analysis in conjunction with semiconductor lifetime estimation models. However, the rain-flow algorithm used in power semiconductor reliability does not consider the time-dependent mean temperature calculation. The equivalent temperature calculation proposed by Nagode et al. is applied to semiconductor lifetime estimation in this paper. A month-long arc furnace load profile is used as a test profile to estimate temperatures in insulated-gate bipolar transistors (IGBTs) in a STATCOM for reactive compensation of load. In conclusion, the degradation in the life of the IGBT power device is predicted basedmore » on time-dependent temperature calculation.« less

Rainflow Algorithm-Based Lifetime Estimation of Power Semiconductors in Utility Applications

DOE PAGES

GopiReddy, Lakshmi Reddy; Tolbert, Leon M.; Ozpineci, Burak; ...

2015-07-15

Rainflow algorithms are one of the popular counting methods used in fatigue and failure analysis in conjunction with semiconductor lifetime estimation models. However, the rain-flow algorithm used in power semiconductor reliability does not consider the time-dependent mean temperature calculation. The equivalent temperature calculation proposed by Nagode et al. is applied to semiconductor lifetime estimation in this paper. A month-long arc furnace load profile is used as a test profile to estimate temperatures in insulated-gate bipolar transistors (IGBTs) in a STATCOM for reactive compensation of load. In conclusion, the degradation in the life of the IGBT power device is predicted basedmore » on time-dependent temperature calculation.« less

Policy evaluation in diabetes prevention and treatment using a population-based macro simulation model: the MICADO model.

PubMed

van der Heijden, A A W A; Feenstra, T L; Hoogenveen, R T; Niessen, L W; de Bruijne, M C; Dekker, J M; Baan, C A; Nijpels, G

2015-12-01

To test a simulation model, the MICADO model, for estimating the long-term effects of interventions in people with and without diabetes. The MICADO model includes micro- and macrovascular diseases in relation to their risk factors. The strengths of this model are its population scope and the possibility to assess parameter uncertainty using probabilistic sensitivity analyses. Outcomes include incidence and prevalence of complications, quality of life, costs and cost-effectiveness. We externally validated MICADO's estimates of micro- and macrovascular complications in a Dutch cohort with diabetes (n = 498,400) by comparing these estimates with national and international empirical data. For the annual number of people undergoing amputations, MICADO's estimate was 592 (95% interquantile range 291-842), which compared well with the registered number of people with diabetes-related amputations in the Netherlands (728). The incidence of end-stage renal disease estimated using the MICADO model was 247 people (95% interquartile range 120-363), which was also similar to the registered incidence in the Netherlands (277 people). MICADO performed well in the validation of macrovascular outcomes of population-based cohorts, while it had more difficulty in reflecting a highly selected trial population. Validation by comparison with independent empirical data showed that the MICADO model simulates the natural course of diabetes and its micro- and macrovascular complications well. As a population-based model, MICADO can be applied for projections as well as scenario analyses to evaluate the long-term (cost-)effectiveness of population-level interventions targeting diabetes and its complications in the Netherlands or similar countries. © 2015 The Authors. Diabetic Medicine © 2015 Diabetes UK.

Lifetime fluoridation exposure and dental caries experience in a military population.

PubMed

Mahoney, Gregory; Slade, Gary D; Kitchener, Scott; Barnett, Adrian

2008-12-01

While there is good evidence of caries-preventive benefits of fluoride in drinking water among children and adolescents, there is little information about effectiveness of water fluoridation among adults. To determine whether exposure to fluoride in drinking water is associated with caries experience in Australian Defence Force (ADF) personnel. Cross-sectional study of 876 deployable ADF personnel aged 17-56 years. At each person's mandatory annual dental examination, military dentists recorded the number of decayed, missing and filled teeth (DMFT) using visual, tactile and radiographic criteria. Participants also completed a questionnaire, listing residential locations in each year from 1964 to 2003. People were classified into four categories according to the percentage of their lifetime living in places with fluoridated water: <10%, 10% to <50%, 50% to <90% and > or =90%. Mean DMFT was compared among those categories of fluoridation exposure and the association was evaluated statistically using analysis of variance to adjust for age, sex, years of service and rank. Without adjustment for confounders, the mean DMFT (+/-95% confidence interval) was 6.3 +/- 0.8 for <10% fluoridation exposure, 7.8 +/- 0.8 for 10% to <50% exposure, 7.5 +/- 0.7 for 50% to <90% exposure and 4.6 +/- 0.6 for > or =90% exposure (P < 0.01). However, age was inversely associated with mean DMFT and in the <10% exposure group, 91% of people were aged <35 years. Service rank was also significantly associated with both fluoridation exposure and DMFT. After adjustment for all covariates, mean DMFT was 24% lower among people in the two groups with > or =50% exposure compared with the <10% exposure group. Degree of lifetime exposure to fluoridated drinking water was inversely associated with DMFT in a dose-response manner among this adult military population.

Development of a paediatric population-based model of the pharmacokinetics of rivaroxaban.

PubMed

Willmann, Stefan; Becker, Corina; Burghaus, Rolf; Coboeken, Katrin; Edginton, Andrea; Lippert, Jörg; Siegmund, Hans-Ulrich; Thelen, Kirstin; Mück, Wolfgang

2014-01-01

Venous thromboembolism has been increasingly recognised as a clinical problem in the paediatric population. Guideline recommendations for antithrombotic therapy in paediatric patients are based mainly on extrapolation from adult clinical trial data, owing to the limited number of clinical trials in paediatric populations. The oral, direct Factor Xa inhibitor rivaroxaban has been approved in adult patients for several thromboembolic disorders, and its well-defined pharmacokinetic and pharmacodynamic characteristics and efficacy and safety profiles in adults warrant further investigation of this agent in the paediatric population. The objective of this study was to develop and qualify a physiologically based pharmacokinetic (PBPK) model for rivaroxaban doses of 10 and 20 mg in adults and to scale this model to the paediatric population (0-18 years) to inform the dosing regimen for a clinical study of rivaroxaban in paediatric patients. Experimental data sets from phase I studies supported the development and qualification of an adult PBPK model. This adult PBPK model was then scaled to the paediatric population by including anthropometric and physiological information, age-dependent clearance and age-dependent protein binding. The pharmacokinetic properties of rivaroxaban in virtual populations of children were simulated for two body weight-related dosing regimens equivalent to 10 and 20 mg once daily in adults. The quality of the model was judged by means of a visual predictive check. Subsequently, paediatric simulations of the area under the plasma concentration-time curve (AUC), maximum (peak) plasma drug concentration (C max) and concentration in plasma after 24 h (C 24h) were compared with the adult reference simulations. Simulations for AUC, C max and C 24h throughout the investigated age range largely overlapped with values obtained for the corresponding dose in the adult reference simulation for both body weight-related dosing regimens. However

Adult lifetime alcohol consumption and invasive epithelial ovarian cancer risk in a population-based case-control study.

PubMed

Cook, Linda S; Leung, Andy C Y; Swenerton, Kenneth; Gallagher, Richard P; Magliocco, Anthony; Steed, Helen; Koebel, Martin; Nation, Jill; Eshragh, Sima; Brooks-Wilson, Angela; Le, Nhu D

2016-02-01

Meta-analyses report a null association between recent alcohol consumption and ovarian cancer risk. However, because few studies investigated different types of alcohol over adult ages, we investigated adult lifetime and type (beer, wine, spirits) of consumption and risk. Consumption after age 20years was ascertained in 1144 invasive epithelial ovarian cancer cases and 2513 controls in a population-based case-control study (Alberta and British Columbia, Canada, 2001-2012). Non-drinkers consumed any types of alcohol <12 times per year on average. Logistic regression was use to estimate adjusted odds ratios [aOR] and 95% confidence intervals [CIs]. Wine consumption was associated with a risk reduction (aOR=0.67, 95% CI: 0.50-0.88) relative to non-drinkers, but not beer (aOR=1.06, 95% CI: 0.71-1.58) or spirits (aOR=0.98, 95% CI: 0.69-1.39). The reduced risk was stronger for exclusive red wine drinkers (aOR=0.44, 95% CI: 0.19-0.92) than white wine drinkers (aOR=0.79, 95% CI: 0.46-1.34), although most women drank both types of wine. Risk decreased with increasing cumulative consumption of any wine (P-trend<0.05) and was evident for the serous histotype. Wine consumption initiated prior to age 50 was associated with a risk reduction (e.g., at 40-49years, aOR=0.58, 95% CI: 0.42-0.78), but not drinking initiated after 50years of age. For any type, level, or age at initiation of alcohol consumption, we found no increased risks. For the moderate consumption in this study, higher levels of wine consumption were generally associated with risk reductions; reductions may be stronger for red wine. Our results suggest that alcohol consumption that is guideline concordant will not increase epithelial ovarian cancer risk. Copyright © 2015 Elsevier Inc. All rights reserved.

Injury risk functions based on population-based finite element model responses: Application to femurs under dynamic three-point bending.

PubMed

Park, Gwansik; Forman, Jason; Kim, Taewung; Panzer, Matthew B; Crandall, Jeff R

2018-02-28

The goal of this study was to explore a framework for developing injury risk functions (IRFs) in a bottom-up approach based on responses of parametrically variable finite element (FE) models representing exemplar populations. First, a parametric femur modeling tool was developed and validated using a subject-specific (SS)-FE modeling approach. Second, principal component analysis and regression were used to identify parametric geometric descriptors of the human femur and the distribution of those factors for 3 target occupant sizes (5th, 50th, and 95th percentile males). Third, distributions of material parameters of cortical bone were obtained from the literature for 3 target occupant ages (25, 50, and 75 years) using regression analysis. A Monte Carlo method was then implemented to generate populations of FE models of the femur for target occupants, using a parametric femur modeling tool. Simulations were conducted with each of these models under 3-point dynamic bending. Finally, model-based IRFs were developed using logistic regression analysis, based on the moment at fracture observed in the FE simulation. In total, 100 femur FE models incorporating the variation in the population of interest were generated, and 500,000 moments at fracture were observed (applying 5,000 ultimate strains for each synthesized 100 femur FE models) for each target occupant characteristics. Using the proposed framework on this study, the model-based IRFs for 3 target male occupant sizes (5th, 50th, and 95th percentiles) and ages (25, 50, and 75 years) were developed. The model-based IRF was located in the 95% confidence interval of the test-based IRF for the range of 15 to 70% injury risks. The 95% confidence interval of the developed IRF was almost in line with the mean curve due to a large number of data points. The framework proposed in this study would be beneficial for developing the IRFs in a bottom-up manner, whose range of variabilities is informed by the population-based

Predicting a future lifetime through Box-Cox transformation.

PubMed

Yang, Z

1999-09-01

In predicting a future lifetime based on a sample of past lifetimes, the Box-Cox transformation method provides a simple and unified procedure that is shown in this article to meet or often outperform the corresponding frequentist solution in terms of coverage probability and average length of prediction intervals. Kullback-Leibler information and second-order asymptotic expansion are used to justify the Box-Cox procedure. Extensive Monte Carlo simulations are also performed to evaluate the small sample behavior of the procedure. Certain popular lifetime distributions, such as Weibull, inverse Gaussian and Birnbaum-Saunders are served as illustrative examples. One important advantage of the Box-Cox procedure lies in its easy extension to linear model predictions where the exact frequentist solutions are often not available.

Characterization of Initial Parameter Information for Lifetime Prediction of Electronic Devices.

PubMed

Li, Zhigang; Liu, Boying; Yuan, Mengxiong; Zhang, Feifei; Guo, Jiaqiang

2016-01-01

Newly manufactured electronic devices are subject to different levels of potential defects existing among the initial parameter information of the devices. In this study, a characterization of electromagnetic relays that were operated at their optimal performance with appropriate and steady parameter values was performed to estimate the levels of their potential defects and to develop a lifetime prediction model. First, the initial parameter information value and stability were quantified to measure the performance of the electronics. In particular, the values of the initial parameter information were estimated using the probability-weighted average method, whereas the stability of the parameter information was determined by using the difference between the extrema and end points of the fitting curves for the initial parameter information. Second, a lifetime prediction model for small-sized samples was proposed on the basis of both measures. Finally, a model for the relationship of the initial contact resistance and stability over the lifetime of the sampled electromagnetic relays was proposed and verified. A comparison of the actual and predicted lifetimes of the relays revealed a 15.4% relative error, indicating that the lifetime of electronic devices can be predicted based on their initial parameter information.

Characterization of Initial Parameter Information for Lifetime Prediction of Electronic Devices

PubMed Central

Li, Zhigang; Liu, Boying; Yuan, Mengxiong; Zhang, Feifei; Guo, Jiaqiang

2016-01-01

Newly manufactured electronic devices are subject to different levels of potential defects existing among the initial parameter information of the devices. In this study, a characterization of electromagnetic relays that were operated at their optimal performance with appropriate and steady parameter values was performed to estimate the levels of their potential defects and to develop a lifetime prediction model. First, the initial parameter information value and stability were quantified to measure the performance of the electronics. In particular, the values of the initial parameter information were estimated using the probability-weighted average method, whereas the stability of the parameter information was determined by using the difference between the extrema and end points of the fitting curves for the initial parameter information. Second, a lifetime prediction model for small-sized samples was proposed on the basis of both measures. Finally, a model for the relationship of the initial contact resistance and stability over the lifetime of the sampled electromagnetic relays was proposed and verified. A comparison of the actual and predicted lifetimes of the relays revealed a 15.4% relative error, indicating that the lifetime of electronic devices can be predicted based on their initial parameter information. PMID:27907188

Adult Prevalence of Epilepsy in Spain: EPIBERIA, a Population-Based Study

PubMed Central

Serrano-Castro, Pedro J.; Mauri-Llerda, Jose Angel; Hernández-Ramos, Francisco José; Sánchez-Alvarez, Juan Carlos; Parejo-Carbonell, Beatriz; Quiroga-Subirana, Pablo; Vázquez-Gutierrez, Fernando; Santos-Lasaosa, Sonia; Mendez-Lucena, Carolina; Redondo-Verge, Luis; Tejero-Juste, Carlos; Morandeira-Rivas, Clara; Sancho-Rieger, Jerónimo; Matías-Guiu, Jorge

2015-01-01

Background. This study assesses the lifetime and active prevalence of epilepsy in Spain in people older than 18 years. Methods. EPIBERIA is a population-based epidemiological study of epilepsy prevalence using data from three representative Spanish regions (health districts in Zaragoza, Almería, and Seville) between 2012 and 2013. The study consisted of two phases: screening and confirmation. Participants completed a previously validated questionnaire (EPIBERIA questionnaire) over the telephone. Results. A total of 1741 valid questionnaires were obtained, including 261 (14.99%) raising a suspicion of epilepsy. Of these suspected cases, 216 (82.75%) agreed to participate in phase 2. Of the phase 2 participants, 22 met the International League Against Epilepsy's diagnostic criteria for epilepsy. The estimated lifetime prevalence, adjusted by age and sex per 1,000 people, was 14.87 (95% CI: 9.8–21.9). Active prevalence was 5.79 (95% CI: 2.8–10.6). No significant age, sex, or regional differences in prevalence were detected. Conclusions. EPIBERIA provides the most accurate estimate of epilepsy prevalence in the Mediterranean region based on its original methodology and its adherence to ILAE recommendations. We highlight that the lifetime prevalence and inactive epilepsy prevalence figures observed here were compared to other epidemiological studies. PMID:26783554

A genetic algorithm based global search strategy for population pharmacokinetic/pharmacodynamic model selection

PubMed Central

Sale, Mark; Sherer, Eric A

2015-01-01

The current algorithm for selecting a population pharmacokinetic/pharmacodynamic model is based on the well-established forward addition/backward elimination method. A central strength of this approach is the opportunity for a modeller to continuously examine the data and postulate new hypotheses to explain observed biases. This algorithm has served the modelling community well, but the model selection process has essentially remained unchanged for the last 30 years. During this time, more robust approaches to model selection have been made feasible by new technology and dramatic increases in computation speed. We review these methods, with emphasis on genetic algorithm approaches and discuss the role these methods may play in population pharmacokinetic/pharmacodynamic model selection. PMID:23772792

LCP- LIFETIME COST AND PERFORMANCE MODEL FOR DISTRIBUTED PHOTOVOLTAIC SYSTEMS

NASA Technical Reports Server (NTRS)

Borden, C. S.

1994-01-01

The Lifetime Cost and Performance (LCP) Model was developed to assist in the assessment of Photovoltaic (PV) system design options. LCP is a simulation of the performance, cost, and revenue streams associated with distributed PV power systems. LCP provides the user with substantial flexibility in specifying the technical and economic environment of the PV application. User-specified input parameters are available to describe PV system characteristics, site climatic conditions, utility purchase and sellback rate structures, discount and escalation rates, construction timing, and lifetime of the system. Such details as PV array orientation and tilt angle, PV module and balance-of-system performance attributes, and the mode of utility interconnection are user-specified. LCP assumes that the distributed PV system is utility grid interactive without dedicated electrical storage. In combination with a suitable economic model, LCP can provide an estimate of the expected net present worth of a PV system to the owner, as compared to electricity purchased from a utility grid. Similarly, LCP might be used to perform sensitivity analyses to identify those PV system parameters having significant impact on net worth. The user describes the PV system configuration to LCP via the basic electrical components. The module is the smallest entity in the PV system which is modeled. A PV module is defined in the simulation by its short circuit current, which varies over the system lifetime due to degradation and failure. Modules are wired in series to form a branch circuit. Bypass diodes are allowed between modules in the branch circuits. Branch circuits are then connected in parallel to form a bus. A collection of buses is connected in parallel to form an increment to capacity of the system. By choosing the appropriate series-parallel wiring design, the user can specify the current, voltage, and reliability characteristics of the system. LCP simulation of system performance is site

SO2 Emissions and Lifetimes: Estimates from Inverse Modeling Using In Situ and Global, Space-Based (SCIAMACHY and OMI) Observations

NASA Technical Reports Server (NTRS)

Lee, Chulkyu; Martin Randall V.; vanDonkelaar, Aaron; Lee, Hanlim; Dickerson, RUssell R.; Hains, Jennifer C.; Krotkov, Nickolay; Richter, Andreas; Vinnikov, Konstantine; Schwab, James J.

2011-01-01

Top-down constraints on global sulfur dioxide (SO2) emissions are inferred through inverse modeling using SO2 column observations from two satellite instruments (SCIAMACHY and OMI). We first evaluated the S02 column observations with surface SO2 measurements by applying local scaling factors from a global chemical transport model (GEOS-Chem) to SO2 columns retrieved from the satellite instruments. The resulting annual mean surface SO2 mixing ratios for 2006 exhibit a significant spatial correlation (r=0.86, slope=0.91 for SCIAMACHY and r=0.80, slope = 0.79 for OMI) with coincident in situ measurements from monitoring networks throughout the United States and Canada. We evaluate the GEOS-Chem simulation of the SO2 lifetime with that inferred from in situ measurements to verity the applicability of GEOS-Chem for inversion of SO2 columns to emissions. The seasonal mean SO2 lifetime calculated with the GEOS-Chem model over the eastern United States is 13 h in summer and 48 h in winter, compared to lifetimes inferred from in situ measurements of 19 +/- 7 h in summer and 58 +/- 20 h in winter. We apply SO2 columns from SCIAMACHY and OMI to derive a top-down anthropogenic SO2 emission inventory over land by using the local GEOS-Chem relationship between SO2 columns and emissions. There is little seasonal variation in the top-down emissions (<15%) over most major industrial regions providing some confidence in the method. Our global estimate for annual land surface anthropogenic SO2 emissions (52.4 Tg S/yr from SCIAMACHY and 49.9 Tg S / yr from OMI) closely agrees with the bottom-up emissions (54.6 Tg S/yr) in the GEOS-Chem model and exhibits consistency in global distributions with the bottom-up emissions (r = 0.78 for SCIAMACHY, and r = 0.77 for OMI). However, there are significant regional differences.

Model-based prediction of nephropathia epidemica outbreaks based on climatological and vegetation data and bank vole population dynamics.

PubMed

Haredasht, S Amirpour; Taylor, C J; Maes, P; Verstraeten, W W; Clement, J; Barrios, M; Lagrou, K; Van Ranst, M; Coppin, P; Berckmans, D; Aerts, J-M

2013-11-01

Wildlife-originated zoonotic diseases in general are a major contributor to emerging infectious diseases. Hantaviruses more specifically cause thousands of human disease cases annually worldwide, while understanding and predicting human hantavirus epidemics pose numerous unsolved challenges. Nephropathia epidemica (NE) is a human infection caused by Puumala virus, which is naturally carried and shed by bank voles (Myodes glareolus). The objective of this study was to develop a method that allows model-based predicting 3 months ahead of the occurrence of NE epidemics. Two data sets were utilized to develop and test the models. These data sets were concerned with NE cases in Finland and Belgium. In this study, we selected the most relevant inputs from all the available data for use in a dynamic linear regression (DLR) model. The number of NE cases in Finland were modelled using data from 1996 to 2008. The NE cases were predicted based on the time series data of average monthly air temperature (°C) and bank voles' trapping index using a DLR model. The bank voles' trapping index data were interpolated using a related dynamic harmonic regression model (DHR). Here, the DLR and DHR models used time-varying parameters. Both the DHR and DLR models were based on a unified state-space estimation framework. For the Belgium case, no time series of the bank voles' population dynamics were available. Several studies, however, have suggested that the population of bank voles is related to the variation in seed production of beech and oak trees in Northern Europe. Therefore, the NE occurrence pattern in Belgium was predicted based on a DLR model by using remotely sensed phenology parameters of broad-leaved forests, together with the oak and beech seed categories and average monthly air temperature (°C) using data from 2001 to 2009. Our results suggest that even without any knowledge about hantavirus dynamics in the host population, the time variation in NE outbreaks in Finland

Reliability and Validity of an Internet-based Questionnaire Measuring Lifetime Physical Activity

PubMed Central

De Vera, Mary A.; Ratzlaff, Charles; Doerfling, Paul; Kopec, Jacek

2010-01-01

Lifetime exposure to physical activity is an important construct for evaluating associations between physical activity and disease outcomes, given the long induction periods in many chronic diseases. The authors' objective in this study was to evaluate the measurement properties of the Lifetime Physical Activity Questionnaire (L-PAQ), a novel Internet-based, self-administered instrument measuring lifetime physical activity, among Canadian men and women in 2005–2006. Reliability was examined using a test-retest study. Validity was examined in a 2-part study consisting of 1) comparisons with previously validated instruments measuring similar constructs, the Lifetime Total Physical Activity Questionnaire (LT-PAQ) and the Chasan-Taber Physical Activity Questionnaire (CT-PAQ), and 2) a priori hypothesis tests of constructs measured by the L-PAQ. The L-PAQ demonstrated good reliability, with intraclass correlation coefficients ranging from 0.67 (household activity) to 0.89 (sports/recreation). Comparison between the L-PAQ and the LT-PAQ resulted in Spearman correlation coefficients ranging from 0.41 (total activity) to 0.71 (household activity); comparison between the L-PAQ and the CT-PAQ yielded coefficients of 0.58 (sports/recreation), 0.56 (household activity), and 0.50 (total activity). L-PAQ validity was further supported by observed relations between the L-PAQ and sociodemographic variables, consistent with a priori hypotheses. Overall, the L-PAQ is a useful instrument for assessing multiple domains of lifetime physical activity with acceptable reliability and validity. PMID:20876666

Reliability and validity of an internet-based questionnaire measuring lifetime physical activity.

PubMed

De Vera, Mary A; Ratzlaff, Charles; Doerfling, Paul; Kopec, Jacek

2010-11-15

Lifetime exposure to physical activity is an important construct for evaluating associations between physical activity and disease outcomes, given the long induction periods in many chronic diseases. The authors' objective in this study was to evaluate the measurement properties of the Lifetime Physical Activity Questionnaire (L-PAQ), a novel Internet-based, self-administered instrument measuring lifetime physical activity, among Canadian men and women in 2005-2006. Reliability was examined using a test-retest study. Validity was examined in a 2-part study consisting of 1) comparisons with previously validated instruments measuring similar constructs, the Lifetime Total Physical Activity Questionnaire (LT-PAQ) and the Chasan-Taber Physical Activity Questionnaire (CT-PAQ), and 2) a priori hypothesis tests of constructs measured by the L-PAQ. The L-PAQ demonstrated good reliability, with intraclass correlation coefficients ranging from 0.67 (household activity) to 0.89 (sports/recreation). Comparison between the L-PAQ and the LT-PAQ resulted in Spearman correlation coefficients ranging from 0.41 (total activity) to 0.71 (household activity); comparison between the L-PAQ and the CT-PAQ yielded coefficients of 0.58 (sports/recreation), 0.56 (household activity), and 0.50 (total activity). L-PAQ validity was further supported by observed relations between the L-PAQ and sociodemographic variables, consistent with a priori hypotheses. Overall, the L-PAQ is a useful instrument for assessing multiple domains of lifetime physical activity with acceptable reliability and validity.

Global-mean BC lifetime as an indicator of model skill? Constraining the vertical aerosol distribution using aircraft observations

NASA Astrophysics Data System (ADS)

Lund, M. T.; Samset, B. H.; Skeie, R. B.; Berntsen, T.

2017-12-01

Several recent studies have used observations from the HIPPO flight campaigns to constrain the modeled vertical distribution of black carbon (BC) over the Pacific. Results indicate a relatively linear relationship between global-mean atmospheric BC residence time, or lifetime, and bias in current models. A lifetime of less than 5 days is necessary for models to reasonably reproduce these observations. This is shorter than what many global models predict, which will in turn affect their estimates of BC climate impacts. Here we use the chemistry-transport model OsloCTM to examine whether this relationship between global BC lifetime and model skill also holds for a broader a set of flight campaigns from 2009-2013 covering both remote marine and continental regions at a range of latitudes. We perform four sets of simulations with varying scavenging efficiency to obtain a spread in the modeled global BC lifetime and calculate the model error and bias for each campaign and region. Vertical BC profiles are constructed using an online flight simulator, as well by averaging and interpolating monthly mean model output, allowing us to quantify sampling errors arising when measurements are compared with model output at different spatial and temporal resolutions. Using the OsloCTM coupled with a microphysical aerosol parameterization, we investigate the sensitivity of modeled BC vertical distribution to uncertainties in the aerosol aging and scavenging processes in more detail. From this, we can quantify how model uncertainties in the BC life cycle propagate into uncertainties in its climate impacts. For most campaigns and regions, a short global-mean BC lifetime corresponds with the lowest model error and bias. On an aggregated level, sampling errors appear to be small, but larger differences are seen in individual regions. However, we also find that model-measurement discrepancies in BC vertical profiles cannot be uniquely attributed to uncertainties in a single process or

Fluorescence lifetime imaging ophthalmoscopy.

PubMed

Dysli, Chantal; Wolf, Sebastian; Berezin, Mikhail Y; Sauer, Lydia; Hammer, Martin; Zinkernagel, Martin S

2017-09-01

Imaging techniques based on retinal autofluorescence have found broad applications in ophthalmology because they are extremely sensitive and noninvasive. Conventional fundus autofluorescence imaging measures fluorescence intensity of endogenous retinal fluorophores. It mainly derives its signal from lipofuscin at the level of the retinal pigment epithelium. Fundus autofluorescence, however, can not only be characterized by the spatial distribution of the fluorescence intensity or emission spectrum, but also by a characteristic fluorescence lifetime function. The fluorescence lifetime is the average amount of time a fluorophore remains in the excited state following excitation. Fluorescence lifetime imaging ophthalmoscopy (FLIO) is an emerging imaging modality for in vivo measurement of lifetimes of endogenous retinal fluorophores. Recent reports in this field have contributed to our understanding of the pathophysiology of various macular and retinal diseases. Within this review, the basic concept of fluorescence lifetime imaging is provided. It includes technical background information and correlation with in vitro measurements of individual retinal metabolites. In a second part, clinical applications of fluorescence lifetime imaging and fluorescence lifetime features of selected retinal diseases such as Stargardt disease, age-related macular degeneration, choroideremia, central serous chorioretinopathy, macular holes, diabetic retinopathy, and retinal artery occlusion are discussed. Potential areas of use for fluorescence lifetime imaging ophthalmoscopy will be outlined at the end of this review. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Lifetime environmental tobacco smoke exposure and the risk of chronic obstructive pulmonary disease.

PubMed

Eisner, Mark D; Balmes, John; Katz, Patricia P; Trupin, Laura; Yelin, Edward H; Blanc, Paul D

2005-05-12

Exposure to environmental tobacco smoke (ETS), which contains potent respiratory irritants, may lead to chronic airway inflammation and obstruction. Although ETS exposure appears to cause asthma in children and adults, its role in causing COPD has received limited attention in epidemiologic studies. Using data from a population-based sample of 2,113 U.S. adults aged 55 to 75 years, we examined the association between lifetime ETS exposure and the risk of developing COPD. Participants were recruited from all 48 contiguous U.S. states by random digit dialing. Lifetime ETS exposure was ascertained by structured telephone interview. We used a standard epidemiologic approach to define COPD based on a self-reported physician diagnosis of chronic bronchitis, emphysema, or COPD. Higher cumulative lifetime home and work exposure were associated with a greater risk of COPD. The highest quartile of lifetime home ETS exposure was associated with a greater risk of COPD, controlling for age, sex, race, personal smoking history, educational attainment, marital status, and occupational exposure to vapors, gas, dusts, or fumes during the longest held job (OR 1.55; 95% CI 1.09 to 2.21). The highest quartile of lifetime workplace ETS exposure was also related to a greater risk of COPD (OR 1.36; 95% CI 1.002 to 1.84). The population attributable fraction was 11% for the highest quartile of home ETS exposure and 7% for work exposure. ETS exposure may be an important cause of COPD. Consequently, public policies aimed at preventing public smoking may reduce the burden of COPD-related death and disability, both by reducing direct smoking and ETS exposure.

Lifetime testing results and diagnostic performance prediction of linear coolers at Thales Cryogenics

NASA Astrophysics Data System (ADS)

van der Weijden, H.; Benschop, T.; van de Groep, W.; Willems, D.

2011-06-01

Thales Cryogenics (TCBV) has an extensive background in delivering long-life cryogenic coolers for military, civil and space programs. During the last years many technical improvements have increased the lifetime of coolers resulting in significantly higher MTTF's. Lifetime endurance tests are used to validate these performance increases. An update will be given on lifetime test of a selection of TCBV's coolers. MTTF figures indicate the statistical average lifetimes for a large population of coolers. However, for the user of IR camera's and spectrometers a detailed view on the performance of an individual cooler and the possible impact of its performance degradation during its lifetime is very important. Thales Cryogenics is developing Cooler Diagnostic Software (CDS), which can be implemented in the firmware of its DSP based cooler drive electronics. With this implemented software the monitoring of the main cooler parameters during the lifetime in the equipment will be possible, including the prediction of the expected cooler performance availability. Based on this software it will be possible to analyze the status of the cooler inside the equipment and, supported by the lifetime knowledge at Thales Cryogenics, make essential choices on the maintenance of equipment and the replacement of coolers. In the paper, we will give an overview of potential situations in which such a predictive algorithm can be used. We will present the required interaction with future users to make an optimal interaction and interpretation of the generated data possible.

Lifetime of heavy hypernuclei and its implications on the weak ΛN interaction

NASA Astrophysics Data System (ADS)

Cassing, W.; Jarczyk, L.; Kamys, B.; Kulessa, P.; Ohm, H.; Pysz, K.; Rudy, Z.; Schult, O. W. B.; Ströher, H.

The lifetime of the Λ-hyperon in heavy hypernuclei measured in proton-Au, -Bi and -U collisions by the COSY-13 Collaboration at COSY-Jülich has been analyzed to yield τΛ = (145+/-11) ps. This value for τΛ is compatible with the lifetime extracted from antiproton annihilation on Bi and U targets, albeit much more accurate. Theoretical models based on the meson exchange picture and assuming the validity of the phenomenological ΔI = 1/2 rule predict the lifetime of heavy hypernuclei to be significantly larger (2-3 standard deviations). Such large differences indicate that at least one of the assumptions in these models is not fulfilled. A much better reproduction of the lifetimes of heavy hypernuclei is achieved in the phase space model, if the ΔI = 1/2 rule is discarded in the nonmesonic Λ decay.

DLTPulseGenerator: A library for the simulation of lifetime spectra based on detector-output pulses

NASA Astrophysics Data System (ADS)

Petschke, Danny; Staab, Torsten E. M.

2018-01-01

The quantitative analysis of lifetime spectra relevant in both life and materials sciences presents one of the ill-posed inverse problems and, hence, leads to most stringent requirements on the hardware specifications and the analysis algorithms. Here we present DLTPulseGenerator, a library written in native C++ 11, which provides a simulation of lifetime spectra according to the measurement setup. The simulation is based on pairs of non-TTL detector output-pulses. Those pulses require the Constant Fraction Principle (CFD) for the determination of the exact timing signal and, thus, the calculation of the time difference i.e. the lifetime. To verify the functionality, simulation results were compared to experimentally obtained data using Positron Annihilation Lifetime Spectroscopy (PALS) on pure tin.

The prevalence of lifetime abuse among older adults in seven European countries.

PubMed

Eslami, Bahareh; Viitasara, Eija; Macassa, Gloria; Melchiorre, Maria Gabriella; Lindert, Jutta; Stankunas, Mindaugas; Torres-Gonzalez, Francisco; Barros, Henrique; Ioannidi-Kapolou, Elisabeth; Soares, Joaquim J F

2016-11-01

To investigate the lifetime prevalence rate of abuse among older persons and to scrutinize the associated factors (e.g. demographics). This cross-sectional population-based study had 4467 participants, aged 60-84, from seven European cities. Abuse (psychological, physical, sexual, financial and injuries) was measured based on The Revised Conflict Tactics Scale, and the UK survey of abuse/neglect of older people. Over 34 % of participants reported experiencing lifetime psychological, 11.5 % physical, 18.5 % financial and 5 % sexual abuse and 4.3 % reported injuries. Lifetime psychological abuse was associated with country, younger age, education and alcohol consumption; physical abuse with country, age, not living in partnership; injuries with country, female sex, age, education, not living in partnership; financial abuse with country, age, not living in partnership, education, benefiting social/partner income, drinking alcohol; and sexual abuse with country, female sex and financial strain. High lifetime prevalence rates confirm that elder abuse is a considerable public health problem warranting further longitudinal studies. Country of residence is an independent factor associated with all types of elder abuse which highlights the importance of national interventions alongside international collaborations.

Mid-Infrared Lifetime Imaging for Viability Evaluation of Lettuce Seeds Based on Time-Dependent Thermal Decay Characterization

PubMed Central

Kim, Ghiseok; Kim, Geon Hee; Ahn, Chi-Kook; Yoo, Yoonkyu; Cho, Byoung-Kwan

2013-01-01

An infrared lifetime thermal imaging technique for the measurement of lettuce seed viability was evaluated. Thermal emission signals from mid-infrared images of healthy seeds and seeds aged for 24, 48, and 72 h were obtained and reconstructed using regression analysis. The emission signals were fitted with a two-term exponential model that had two amplitudes and two time variables as lifetime parameters. The lifetime thermal decay parameters were significantly different for seeds with different aging times. Single-seed viability was visualized using thermal lifetime images constructed from the calculated lifetime parameter values. The time-dependent thermal signal decay characteristics, along with the decay amplitude and delay time images, can be used to distinguish aged lettuce seeds from normal seeds. PMID:23529120

The quality-of-life burden of knee osteoarthritis in New Zealand adults: A model-based evaluation

PubMed Central

Wilson, Ross; Hansen, Paul; Losina, Elena

2017-01-01

Background Knee osteoarthritis is a leading global cause of health-related quality of life loss. The aim of this project was to quantify health losses arising from knee osteoarthritis in New Zealand (NZ) in terms of quality-adjusted life years (QALYs) lost. Methods The Osteoarthritis Policy Model (OAPol), a validated Monte Carlo computer simulation model, was used to estimate QALYs lost due to knee osteoarthritis in the NZ adult population aged 40–84 over their lifetimes from the base year of 2006 until death. Data were from the NZ Health Survey, NZ Burden of Diseases, NZ Census, and relevant literature. QALYs were derived from NZ EQ-5D value set 2. Sensitivity to health state valuation, disease and pain prevalence were assessed in secondary analyses. Results Based on NZ EQ-5D health state valuations, mean health losses due to knee osteoarthritis over people’s lifetimes in NZ are 3.44 QALYs per person, corresponding to 467,240 QALYs across the adult population. Average estimated per person QALY losses are higher for non-Māori females (3.55) than Māori females (3.38), and higher for non-Māori males (3.34) than Māori males (2.60). The proportion of QALYs lost out of the total quality-adjusted life expectancy for those without knee osteoarthritis is similar across all subgroups, ranging from 20 to 23 percent. Conclusions At both the individual and population levels, knee osteoarthritis is responsible for large lifetime QALY losses. QALY losses are higher for females than males due to greater prevalence of knee osteoarthritis and higher life expectancy, and lower for Māori than non-Māori due to lower life expectancy. Large health gains are potentially realisable from public health and policy measures aimed at decreasing incidence, progression, pain, and disability of osteoarthritis. PMID:29065119

The quality-of-life burden of knee osteoarthritis in New Zealand adults: A model-based evaluation.

PubMed

Abbott, J Haxby; Usiskin, Ilana M; Wilson, Ross; Hansen, Paul; Losina, Elena

2017-01-01

Knee osteoarthritis is a leading global cause of health-related quality of life loss. The aim of this project was to quantify health losses arising from knee osteoarthritis in New Zealand (NZ) in terms of quality-adjusted life years (QALYs) lost. The Osteoarthritis Policy Model (OAPol), a validated Monte Carlo computer simulation model, was used to estimate QALYs lost due to knee osteoarthritis in the NZ adult population aged 40-84 over their lifetimes from the base year of 2006 until death. Data were from the NZ Health Survey, NZ Burden of Diseases, NZ Census, and relevant literature. QALYs were derived from NZ EQ-5D value set 2. Sensitivity to health state valuation, disease and pain prevalence were assessed in secondary analyses. Based on NZ EQ-5D health state valuations, mean health losses due to knee osteoarthritis over people's lifetimes in NZ are 3.44 QALYs per person, corresponding to 467,240 QALYs across the adult population. Average estimated per person QALY losses are higher for non-Māori females (3.55) than Māori females (3.38), and higher for non-Māori males (3.34) than Māori males (2.60). The proportion of QALYs lost out of the total quality-adjusted life expectancy for those without knee osteoarthritis is similar across all subgroups, ranging from 20 to 23 percent. At both the individual and population levels, knee osteoarthritis is responsible for large lifetime QALY losses. QALY losses are higher for females than males due to greater prevalence of knee osteoarthritis and higher life expectancy, and lower for Māori than non-Māori due to lower life expectancy. Large health gains are potentially realisable from public health and policy measures aimed at decreasing incidence, progression, pain, and disability of osteoarthritis.

The inverse power law model for the lifetime of a mylar-polyurethane laminated dc hv insulating structure

NASA Astrophysics Data System (ADS)

Kalkanis, G.; Rosso, E.

1989-09-01

Results of an accelerated test on the lifetime of a mylar-polyurethane laminated dc high voltage insulating structure are reported. This structure consists of mylar ribbons placed side by side in a number of layers, staggered and glued together with a polyurethane adhesive. The lifetime until breakdown as a function of extremely high values of voltage stress is measured and represented by a mathematical model, the inverse power law model with a 2-parameter Weibull lifetime distribution. The statistical treatment of the data — either by graphical or by analytical methods — allowed us to estimate the lifetime distribution and confidence bounds for any required normal voltage stress. The laminated structure under consideration is, according to the analysis, a very reliable dc hv insulating material, with a very good life performance according to the inverse power law model, and with an exponent of voltage stress equal to 6. A large insulator of cylindrical shape with this kind of laminated structure can be constructed by winding helically a mylar ribbon in a number of layers.

Bayesian population analysis of a washin-washout physiologically based pharmacokinetic model for acetone

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

Moerk, Anna-Karin, E-mail: anna-karin.mork@ki.s; Jonsson, Fredrik; Pharsight, a Certara company, St. Louis, MO

2009-11-01

The aim of this study was to derive improved estimates of population variability and uncertainty of physiologically based pharmacokinetic (PBPK) model parameters, especially of those related to the washin-washout behavior of polar volatile substances. This was done by optimizing a previously published washin-washout PBPK model for acetone in a Bayesian framework using Markov chain Monte Carlo simulation. The sensitivity of the model parameters was investigated by creating four different prior sets, where the uncertainty surrounding the population variability of the physiological model parameters was given values corresponding to coefficients of variation of 1%, 25%, 50%, and 100%, respectively. The PBPKmore » model was calibrated to toxicokinetic data from 2 previous studies where 18 volunteers were exposed to 250-550 ppm of acetone at various levels of workload. The updated PBPK model provided a good description of the concentrations in arterial, venous, and exhaled air. The precision of most of the model parameter estimates was improved. New information was particularly gained on the population distribution of the parameters governing the washin-washout effect. The results presented herein provide a good starting point to estimate the target dose of acetone in the working and general populations for risk assessment purposes.« less

Power management of remote microgrids considering battery lifetime

NASA Astrophysics Data System (ADS)

Chalise, Santosh

Currently, 20% (1.3 billion) of the world's population still lacks access to electricity and many live in remote areas where connection to the grid is not economical or practical. Remote microgrids could be the solution to the problem because they are designed to provide power for small communities within clearly defined electrical boundaries. Reducing the cost of electricity for remote microgrids can help to increase access to electricity for populations in remote areas and developing countries. The integration of renewable energy and batteries in diesel based microgrids has shown to be effective in reducing fuel consumption. However, the operational cost remains high due to the low lifetime of batteries, which are heavily used to improve the system's efficiency. In microgrid operation, a battery can act as a source to augment the generator or a load to ensure full load operation. In addition, a battery increases the utilization of PV by storing extra energy. However, the battery has a limited energy throughput. Therefore, it is required to provide balance between fuel consumption and battery lifetime throughput in order to lower the cost of operation. This work presents a two-layer power management system for remote microgrids. First layer is day ahead scheduling, where power set points of dispatchable resources were calculated. Second layer is real time dispatch, where schedule set points from the first layer are accepted and resources are dispatched accordingly. A novel scheduling algorithm is proposed for a dispatch layer, which considers the battery lifetime in optimization and is expected to reduce the operational cost of the microgrid. This method is based on a goal programming approach which has the fuel and the battery wear cost as two objectives to achieve. The effectiveness of this method was evaluated through a simulation study of a PV-diesel hybrid microgrid using deterministic and stochastic approach of optimization.

Agent-Based Phytoplankton Models of Cellular and Population Processes: Fostering Individual-Based Learning in Undergraduate Research

NASA Astrophysics Data System (ADS)

Berges, J. A.; Raphael, T.; Rafa Todd, C. S.; Bate, T. C.; Hellweger, F. L.

2016-02-01

Engaging undergraduate students in research projects that require expertise in multiple disciplines (e.g. cell biology, population ecology, and mathematical modeling) can be challenging because they have often not developed the expertise that allows them to participate at a satisfying level. Use of agent-based modeling can allow exploration of concepts at more intuitive levels, and encourage experimentation that emphasizes processes over computational skills. Over the past several years, we have involved undergraduate students in projects examining both ecological and cell biological aspects of aquatic microbial biology, using the freely-downloadable, agent-based modeling environment NetLogo (https://ccl.northwestern.edu/netlogo/). In Netlogo, actions of large numbers of individuals can be simulated, leading to complex systems with emergent behavior. The interface features appealing graphics, monitors, and control structures. In one example, a group of sophomores in a BioMathematics program developed an agent-based model of phytoplankton population dynamics in a pond ecosystem, motivated by observed macroscopic changes in cell numbers (due to growth and death), and driven by responses to irradiance, temperature and a limiting nutrient. In a second example, junior and senior undergraduates conducting Independent Studies created a model of the intracellular processes governing stress and cell death for individual phytoplankton cells (based on parameters derived from experiments using single-cell culturing and flow cytometry), and then this model was embedded in the agents in the pond ecosystem model. In our experience, students with a range of mathematical abilities learned to code quickly and could use the software with varying degrees of sophistication, for example, creation of spatially-explicit two and three-dimensional models. Skills developed quickly and transferred readily to other platforms (e.g. Matlab).

Evaluation of the oxidative stress of psoriatic fibroblasts based on spectral two-photon fluorescence lifetime imaging

NASA Astrophysics Data System (ADS)

Kapsokalyvas, Dimitrios; Barygina, Victoria; Cicchi, Riccardo; Fiorillo, Claudia; Pavone, Francesco S.

2013-02-01

Psoriasis is an autoimmune disease of the skin characterized by hyperkeratosis, hyperproliferation of the epidermis, inflammatory cell accumulation and increased dilatation of dermal papillary blood vessels. Metabolic activity is increased in the epidermis and the dermis. Oxidative stress is high mainly due to reactive oxygen species (ROS) originating from the skin environment and cellular metabolism. We employed a custom multiphoton microscope coupled with a FLIM setup to image primary culture fibroblast cells from perilesional and lesional psoriatic skin in-vitro. Twophoton excited fluorescence images revealed the morphological differences between healthy and psoriatic fibroblasts. Based on the spectral analysis of the NADH and FAD components the oxidative stress was assessed and found to be higher in psoriatic cells. Furthermore the fluorescence lifetime properties were investigated with a TCSPC FLIM module. Mean fluorescence lifetime was found to be longer in psoriatic lesional cells. Analysis of the fast (τ1) and slow (τ2) decay lifetimes revealed a decrease of the ratio of the contribution of the fast (α1) parameter to the contribution of the slow (α2) parameter. The fluorescence in the examined part of the spectrum is attributed mainly to NADH. The decrease of the ratio (α1)/ (α2) is believed to correlate strongly with the anti-oxidant properties of NADH which can lead to the variation of its population in high ROS environment. This methodology could serve as an index of the oxidative status in cells and furthermore could be used to probe the oxidative stress of tissues in-vivo.

r- and K-selection in fluctuating populations is determined by the evolutionary trade-off between two fitness measures: Growth rate and lifetime reproductive success.

PubMed

Engen, Steinar; Saether, Bernt-Erik

2017-01-01

In a stable environment, evolution maximizes growth rates in populations that are not density regulated and the carrying capacity in the case of density regulation. In a fluctuating environment, evolution maximizes a function of growth rate, carrying capacity and environmental variance, tending to r-selection and K-selection under large and small environmental noise, respectively. Here we analyze a model in which birth and death rates depend on density through the same function but with independent strength of density dependence. As a special case, both functions may be linear, corresponding to logistic dynamics. It is shown that evolution maximizes a function of the deterministic growth rate r 0 and the lifetime reproductive success (LRS) R 0 , both defined at small densities, as well as the environmental variance. Under large noise this function is dominated by r 0 and average lifetimes are small, whereas R 0 dominates and lifetimes are larger under small noise. Thus, K-selection is closely linked to selection for large R 0 so that evolution tends to maximize LRS in a stable environment. Consequently, different quantities (r 0 and R 0 ) tend to be maximized at low and high densities, respectively, favoring density-dependent changes in the optimal life history. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

GaN-based superluminescent diodes with long lifetime

NASA Astrophysics Data System (ADS)

Castiglia, A.; Rossetti, M.; Matuschek, N.; Rezzonico, R.; Duelk, M.; Vélez, C.; Carlin, J.-F.; Grandjean, N.

2016-02-01

We report on the reliability of GaN-based super-luminescent light emitting diodes (SLEDs) emitting at a wavelength of 405 nm. We show that the Mg doping level in the p-type layers has an impact on both the device electro-optical characteristics and their reliability. Optimized doping levels allow decreasing the operating voltage on single-mode devices from more than 6 V to less than 5 V for an injection current of 100 mA. Furthermore, maximum output powers as high as 350 mW (for an injection current of 500 mA) have been achieved in continuous-wave operation (CW) at room temperature. Modules with standard and optimized p-type layers were finally tested in terms of lifetime, at a constant output power of 10 mW, in CW operation and at a case temperature of 25 °C. The modules with non-optimized p-type doping showed a fast and remarkable increase in the drive current during the first hundreds of hours together with an increase of the device series resistance. No degradation of the electrical characteristics was observed over 2000 h on devices with optimized p-type layers. The estimated lifetime for those devices was longer than 5000 h.

Dynamic Modeling, Model-Based Control, and Optimization of Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Spivey, Benjamin James

2011-07-01

Solid oxide fuel cells are a promising option for distributed stationary power generation that offers efficiencies ranging from 50% in stand-alone applications to greater than 80% in cogeneration. To advance SOFC technology for widespread market penetration, the SOFC should demonstrate improved cell lifetime and load-following capability. This work seeks to improve lifetime through dynamic analysis of critical lifetime variables and advanced control algorithms that permit load-following while remaining in a safe operating zone based on stress analysis. Control algorithms typically have addressed SOFC lifetime operability objectives using unconstrained, single-input-single-output control algorithms that minimize thermal transients. Existing SOFC controls research has not considered maximum radial thermal gradients or limits on absolute temperatures in the SOFC. In particular, as stress analysis demonstrates, the minimum cell temperature is the primary thermal stress driver in tubular SOFCs. This dissertation presents a dynamic, quasi-two-dimensional model for a high-temperature tubular SOFC combined with ejector and prereformer models. The model captures dynamics of critical thermal stress drivers and is used as the physical plant for closed-loop control simulations. A constrained, MIMO model predictive control algorithm is developed and applied to control the SOFC. Closed-loop control simulation results demonstrate effective load-following, constraint satisfaction for critical lifetime variables, and disturbance rejection. Nonlinear programming is applied to find the optimal SOFC size and steady-state operating conditions to minimize total system costs.

Modeling the Unites States government's economic cost of noise-induced hearing loss for a military population.

PubMed

Tufts, Jennifer B; Weathersby, Paul K; Rodriguez, Francisco A

2010-05-01

The purpose of this paper is to demonstrate the feasibility and utility of developing economic cost models for noise-induced hearing loss (NIHL). First, we outline an economic model of NIHL for a population of US Navy sailors with an "industrial"-type noise exposure. Next, we describe the effect on NIHL-related cost of varying the two central model inputs--the noise-exposure level and the duration of exposure. Such an analysis can help prioritize promising areas, to which limited resources to reduce NIHL-related costs should be devoted. NIHL-related costs borne by the US government were computed on a yearly basis using a finite element approach that took into account varying levels of susceptibility to NIHL. Predicted hearing thresholds for the population were computed with ANSI S3.44-1996 and then used as the basis for the calculation of NIHL-related costs. Annual and cumulative costs were tracked. Noise-exposure level and duration were systematically varied to determine their effects on the expected lifetime NIHL-related cost of a specific US Navy sailor population. Our nominal noise-exposure case [93 dB(A) for six years] yielded a total expected lifetime cost of US $13,472 per sailor, with plausible lower and upper bounds of US $2,500 and US $26,000. Starting with the nominal case, a decrease of 50% in exposure level or duration would yield cost savings of approximately 23% and 19%, respectively. We concluded that a reduction in noise level would be more somewhat more cost-effective than the same percentage reduction in years of exposure. Our economic cost model can be used to estimate the changes in NIHL-related costs that would result from changes in noise-exposure level and/or duration for a single military population. Although the model is limited at present, suggestions are provided for adapting it to civilian populations.

A Constitutive Model for Creep Lifetime of PBO Braided Cord

NASA Technical Reports Server (NTRS)

Sterling, W. J.

2007-01-01

A constitutive model to describe the creep lifetime of PBO braided cord has been developed and fit to laboratory data. The model follows an approach proposed for p-aramid cord in similar applications, and has a Boltzman-type representation that arises from consideration of the failure phenomenon mechanism. The data were obtained using a hydraulic-type universal testing machine, and were analyzed according to Weibull statistics using commercially-available software. The application of concern to the author is NASA's Ultra- Long Duration Balloon and other gossamer spacecraft, but the motivations for the related p-aramid works suggest broader interest.

Increasing accuracy of dispersal kernels in grid-based population models

USGS Publications Warehouse

Slone, D.H.

2011-01-01

Dispersal kernels in grid-based population models specify the proportion, distance and direction of movements within the model landscape. Spatial errors in dispersal kernels can have large compounding effects on model accuracy. Circular Gaussian and Laplacian dispersal kernels at a range of spatial resolutions were investigated, and methods for minimizing errors caused by the discretizing process were explored. Kernels of progressively smaller sizes relative to the landscape grid size were calculated using cell-integration and cell-center methods. These kernels were convolved repeatedly, and the final distribution was compared with a reference analytical solution. For large Gaussian kernels (σ > 10 cells), the total kernel error was <10 &sup-11; compared to analytical results. Using an invasion model that tracked the time a population took to reach a defined goal, the discrete model results were comparable to the analytical reference. With Gaussian kernels that had σ ≤ 0.12 using the cell integration method, or σ ≤ 0.22 using the cell center method, the kernel error was greater than 10%, which resulted in invasion times that were orders of magnitude different than theoretical results. A goal-seeking routine was developed to adjust the kernels to minimize overall error. With this, corrections for small kernels were found that decreased overall kernel error to <10-11 and invasion time error to <5%.

A high-throughput direct fluorescence resonance energy transfer-based assay for analyzing apoptotic proteases using flow cytometry and fluorescence lifetime measurements.

PubMed

Suzuki, Miho; Sakata, Ichiro; Sakai, Takafumi; Tomioka, Hiroaki; Nishigaki, Koichi; Tramier, Marc; Coppey-Moisan, Maïté

2015-12-15

Cytometry is a versatile and powerful method applicable to different fields, particularly pharmacology and biomedical studies. Based on the data obtained, cytometric studies are classified into high-throughput (HTP) or high-content screening (HCS) groups. However, assays combining the advantages of both are required to facilitate research. In this study, we developed a high-throughput system to profile cellular populations in terms of time- or dose-dependent responses to apoptotic stimulations because apoptotic inducers are potent anticancer drugs. We previously established assay systems involving protease to monitor live cells for apoptosis using tunable fluorescence resonance energy transfer (FRET)-based bioprobes. These assays can be used for microscopic analyses or fluorescence-activated cell sorting. In this study, we developed FRET-based bioprobes to detect the activity of the apoptotic markers caspase-3 and caspase-9 via changes in bioprobe fluorescence lifetimes using a flow cytometer for direct estimation of FRET efficiencies. Different patterns of changes in the fluorescence lifetimes of these markers during apoptosis were observed, indicating a relationship between discrete steps in the apoptosis process. The findings demonstrate the feasibility of evaluating collective cellular dynamics during apoptosis. Copyright © 2015 Elsevier Inc. All rights reserved.

Lifetime interpersonal violence and self-reported chlamydia trachomatis diagnosis among California women.

PubMed

Alvarez, Jennifer; Pavao, Joanne; Mack, Katelyn P; Chow, Joan M; Baumrind, Nikki; Kimerling, Rachel

2009-01-01

To examine the relationship between cumulative exposure to various types of interpersonal violence throughout the life span and self-reported history of Chlamydia trachomatis (CT) diagnosis in a population-based sample of California women. This was a cross-sectional analysis of a population-based survey of California women aged 18-44 years (n = 3521). Participants reported their experience of multiple types of interpersonal violence: physical or sexual abuse in childhood or adulthood and intimate partner violence (IPV) in the past 12 months. Current posttraumatic stress disorder (PTSD) and depressive symptoms were also reported. Separate logistic regression models assessed the association between experiencing each type of interpersonal violence, as well as women's cumulative exposure to violence, and past CT diagnosis, adjusting for age, race/ethnicity, and poverty, as well as mental health problems. Six percent of women reported a past diagnosis of CT, and 40.8% reported experiencing at least one type of interpersonal violence in their lifetime. All types of violence were significantly associated with higher odds of having a past CT diagnosis even after controlling for sociodemographics. Women who reported experiencing four or more types of violence experiences had over five times the odds of reporting a lifetime CT diagnosis compared with women who never experienced interpersonal violence (adjusted odds ratio = 5.71, 95% CI 3.27-9.58). Current PTSD and depressive symptoms did not significantly affect the relationship between a woman's cumulative experience of violence and her risk of past CT diagnosis. There is a robust association between experiencing multiple forms of violence and having been diagnosed with CT. Women who seek treatment for sexually transmitted diseases (STDs), such as CT, should be assessed for their lifetime history of violence, especially violence in their current intimate relationships. Sexual risk reduction counseling may also be important

Bilayer Suspension Plasma-Sprayed Thermal Barrier Coatings with Enhanced Thermal Cyclic Lifetime: Experiments and Modeling

NASA Astrophysics Data System (ADS)

Gupta, Mohit; Kumara, Chamara; Nylén, Per

2017-08-01

Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.

Birth month affects lifetime disease risk: a phenome-wide method.

PubMed

Boland, Mary Regina; Shahn, Zachary; Madigan, David; Hripcsak, George; Tatonetti, Nicholas P

2015-09-01

An individual's birth month has a significant impact on the diseases they develop during their lifetime. Previous studies reveal relationships between birth month and several diseases including atherothrombosis, asthma, attention deficit hyperactivity disorder, and myopia, leaving most diseases completely unexplored. This retrospective population study systematically explores the relationship between seasonal affects at birth and lifetime disease risk for 1688 conditions. We developed a hypothesis-free method that minimizes publication and disease selection biases by systematically investigating disease-birth month patterns across all conditions. Our dataset includes 1 749 400 individuals with records at New York-Presbyterian/Columbia University Medical Center born between 1900 and 2000 inclusive. We modeled associations between birth month and 1688 diseases using logistic regression. Significance was tested using a chi-squared test with multiplicity correction. We found 55 diseases that were significantly dependent on birth month. Of these 19 were previously reported in the literature (P < .001), 20 were for conditions with close relationships to those reported, and 16 were previously unreported. We found distinct incidence patterns across disease categories. Lifetime disease risk is affected by birth month. Seasonally dependent early developmental mechanisms may play a role in increasing lifetime risk of disease. © The Author 2015. Published by Oxford University Press on behalf of the American Medical Informatics Association.

Birth month affects lifetime disease risk: a phenome-wide method

PubMed Central

Boland, Mary Regina; Shahn, Zachary; Madigan, David; Hripcsak, George; Tatonetti, Nicholas P

2015-01-01

Objective An individual’s birth month has a significant impact on the diseases they develop during their lifetime. Previous studies reveal relationships between birth month and several diseases including atherothrombosis, asthma, attention deficit hyperactivity disorder, and myopia, leaving most diseases completely unexplored. This retrospective population study systematically explores the relationship between seasonal affects at birth and lifetime disease risk for 1688 conditions. Methods We developed a hypothesis-free method that minimizes publication and disease selection biases by systematically investigating disease-birth month patterns across all conditions. Our dataset includes 1 749 400 individuals with records at New York-Presbyterian/Columbia University Medical Center born between 1900 and 2000 inclusive. We modeled associations between birth month and 1688 diseases using logistic regression. Significance was tested using a chi-squared test with multiplicity correction. Results We found 55 diseases that were significantly dependent on birth month. Of these 19 were previously reported in the literature (P < .001), 20 were for conditions with close relationships to those reported, and 16 were previously unreported. We found distinct incidence patterns across disease categories. Conclusions Lifetime disease risk is affected by birth month. Seasonally dependent early developmental mechanisms may play a role in increasing lifetime risk of disease. PMID:26041386

Environmental Tobacco Smoke and Adult-Onset Asthma: A Population-Based Incident Case–Control Study

PubMed Central

Jaakkola, Maritta S.; Piipari, Ritva; Jaakkola, Niina; Jaakkola, Jouni J. K.

2003-01-01

Objectives. The authors assessed the effects of environmental tobacco smoke (ETS) on the development of asthma in adults. Methods. In the Pirkanmaa district of South Finland, all 21- to 63-year-old adults with new cases of asthma diagnosed during a 2.5-year period (n = 521 case patients, out of 441 000 inhabitants) and a random sample of control subjects from the source population (932 control subjects) participated in a population-based incident case–control study. Results. Risk of asthma was related to workplace ETS exposure (adjusted odds ratio [OR] = 2.16; 95% confidence interval [CI] = 1.26, 3.72) and home exposure (OR = 4.77; 95% CI = 1.29, 17.7) in the past year. Cumulative ETS exposure over a lifetime at work and at home increased the risk. Conclusions. This study indicates for the first time that both cumulative lifetime and recent ETS exposures increase the risk of adult-onset asthma. PMID:14652334

Collision lifetimes and impact statistics of near-Earth asteroids

NASA Technical Reports Server (NTRS)

Bottke, W. F., Jr.; Nolan, M. C.; Greenberg, R.

1993-01-01

We have examined the lifetimes of Near-Earth asteroids (NEA's) by directly computing the collision probabilities with other asteroids and with the terrestrial planets. We compare these to the dynamical lifetimes, and to collisional lifetimes assumed by other workers. We discuss the implications of the differences. The lifetimes of NEA's are important because, along with the statistics of craters on the Earth and Moon, they help us to compute the number of NEA's and the rate at which new NEA's are brought to the vicinity of the Earth. Assuming that the NEA population is in steady-state, the lifetimes determine the flux of new bodies needed to replenish the population. Earlier estimates of the lifetimes ignored (or incompletely accounted for) the differences in the velocities of asteroids as they move in their orbits, so our results differ from (for example) Greenberg and Chapman (1983, Icarus 55, 455) and Wetherill (1988, Icarus 76, 1) by factors of 2 to 10. We have computed the collision rates and relative velocities of NEA's with each other, the main-belt asteroids, and the terrestrial planets, using the corrected method described by Bottke et. al. (1992, GRL, in press). We find that NEA's typically have shorter collisional lifetimes than do main-belt asteroids of the same size, due to their high eccentricities, which typically give them aphelia in the main belt. Consequently, they spend a great deal of time in the main belt, and are moving much slower than the bodies around them, making them 'sitting ducks' for impacts with other asteroids. They cross the paths of many objects, and their typical collision velocities are much higher (10-15 km/s) than the collision velocities (5 km/s) among objects within the main belt. These factors combine to give them substantially shorter lifetimes than had been previously estimated.

Galactic civilizations - Population dynamics and interstellar diffusion

NASA Technical Reports Server (NTRS)

Newman, W. I.; Sagan, C.

1981-01-01

A model is developed of the interstellar diffusion of galactic civilizations which takes into account the population dynamics of such civilizations. The problem is formulated in terms of potential theory, with a family of nonlinear partial differential and difference equations specifying population growth and diffusion for an organism with advantageous genes that undergoes random dispersal while increasing in population locally, and a population at zero population growth. In the case of nonlinear diffusion with growth and saturation, it is found that the colonization wavefront from the nearest independently arisen galactic civilization can have reached the earth only if its lifetime exceeds 2.6 million years, or 20 million years if discretization can be neglected. For zero population growth, the corresponding lifetime is 13 billion years. It is concluded that the earth is uncolonized not because interstellar spacefaring civilizations are rare, but because there are too many worlds to be colonized in the plausible colonization lifetime of nearby civilizations, and that there exist no very old galactic civilizations with a consistent policy of the conquest of inhabited worlds.

Measurement and Perturbation of Morphogen Lifetime: Effects on Gradient Shape

PubMed Central

Drocco, Jeffrey A.; Grimm, Oliver; Tank, David W.; Wieschaus, Eric

2011-01-01

Protein lifetime is of critical importance for most biological processes and plays a central role in cell signaling and embryonic development, where it impacts the absolute concentration of signaling molecules and, potentially, the shape of morphogen gradients. Early conceptual and mathematical models of gradient formation proposed that steady-state gradients are established by an equilibration between the lifetime of a morphogen and its rates of synthesis and diffusion, though whether gradients in fact reach steady state before being read out is a matter of controversy. In any case, this class of models predicts that protein lifetime is a key determinant of both the time to steady state and the spatial extent of a gradient. Using a method that employs repeated photoswitching of a fusion of the morphogen Bicoid (Bcd) and the photoconvertible fluorescent protein Dronpa, we measure and modify the lifetime of Dronpa-Bcd in living Drosophila embryos. We find that the lifetime of Bcd is dynamic, changing from 50 min before mitotic cycle 14 to 15 min during cellularization. Moreover, by measuring total quantities of Bcd over time, we find that the gradient does not reach steady state. Finally, using a nearly continuous low-level conversion to the dark state of Dronpa-Bcd to mimic the effect of increased degradation, we demonstrate that perturbation of protein lifetime changes the characteristic length of the gradient, providing direct support for a mechanism based on synthesis, diffusion, and degradation. PMID:22004733

Modeling wildlife populations with HexSim

EPA Science Inventory

HexSim is a framework for constructing spatially-explicit, individual-based computer models designed for simulating terrestrial wildlife population dynamics and interactions. HexSim is useful for a broad set of modeling applications including population viability analysis for on...

Maintenance of algal endosymbionts in Paramecium bursaria: a simple model based on population dynamics.

PubMed

Iwai, Sosuke; Fujiwara, Kenji; Tamura, Takuro

2016-09-01

Algal endosymbiosis is widely distributed in eukaryotes including many protists and metazoans, and plays important roles in aquatic ecosystems, combining phagotrophy and phototrophy. To maintain a stable symbiotic relationship, endosymbiont population size in the host must be properly regulated and maintained at a constant level; however, the mechanisms underlying the maintenance of algal endosymbionts are still largely unknown. Here we investigate the population dynamics of the unicellular ciliate Paramecium bursaria and its Chlorella-like algal endosymbiont under various experimental conditions in a simple culture system. Our results suggest that endosymbiont population size in P. bursaria was not regulated by active processes such as cell division coupling between the two organisms, or partitioning of the endosymbionts at host cell division. Regardless, endosymbiont population size was eventually adjusted to a nearly constant level once cells were grown with light and nutrients. To explain this apparent regulation of population size, we propose a simple mechanism based on the different growth properties (specifically the nutrient requirements) of the two organisms, and based from this develop a mathematical model to describe the population dynamics of host and endosymbiont. The proposed mechanism and model may provide a basis for understanding the maintenance of algal endosymbionts. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Determinants of lifetime reproduction in female brown bears: early body mass, longevity, and hunting regulations.

PubMed

Zedrosser, Andreas; Pelletier, Fanie; Bischof, Richard; Festa-Bianchet, Marco; Swenson, Jon E

2013-01-01

In iteroparous mammals, conditions experienced early in life may have long-lasting effects on lifetime reproductive success. Human-induced mortality is also an important demographic factor in many populations of large mammals and may influence lifetime reproductive success. Here, we explore the effects of early development, population density, and human hunting on survival and lifetime reproductive success in brown bear (Ursus arctos) females, using a 25-year database of individually marked bears in two populations in Sweden. Survival of yearlings to 2 years was not affected by population density or body mass. Yearlings that remained with their mother had higher survival than independent yearlings, partly because regulations prohibit the harvest of bears in family groups. Although mass as a yearling did not affect juvenile survival, it was positively associated with measures of lifetime reproductive success and individual fitness. The majority of adult female brown bear mortality (72%) in our study was due to human causes, mainly hunting, and many females were killed before they reproduced. Therefore, factors allowing females to survive several hunting seasons had a strong positive effect on lifetime reproductive success. We suggest that, in many hunted populations of large mammals, sport harvest is an important influence on both population dynamics and life histories.

Expert and self-assessment of lifetime symptoms and diagnosis of major depressive disorder in large-scale genetic studies in the general population: comparison of a clinical interview and a self-administered checklist.

PubMed

Martin, Jessica; Streit, Fabian; Treutlein, Jens; Lang, Maren; Frank, Josef; Forstner, Andreas J; Degenhardt, Franziska; Witt, Stephanie H; Schulze, Thomas G; Cichon, Sven; Nöthen, Markus M; Rietschel, Marcella; Strohmaier, Jana

2017-10-01

Major depression disorder (MDD) is a complex neuropsychiatric disorder and an increasing number of genetic risk variants are being identified. Investigation of their influence in the general population requires accurate and efficient assessment of depressive symptoms. Here, clinical interviews conducted by clinicians are the gold standard. We investigated whether valid and reliable clinical phenotypes can be obtained efficiently using self-administered instruments. Lifetime depressive symptoms and lifetime MDD diagnosis were assessed in 464 population-based individuals using a clinical interview and a structured, self-administered checklist. Analyses were carried out of the following: (i) intraclass correlations (ICC) between checklist and interview; (ii) sensitivity/specificity of the checklist; and (iii) the association of interview and checklist with a positive family history of MDD (FH-MDD+). The correspondence of the self-administered checklist with the clinical interview was good for most depressive symptoms (ICC=0.60-0.80) and moderate for MDD diagnosis (ICC=0.45). With the consecutive inclusion of MDD diagnostic criteria, sensitivity decreased from 0.67 to 0.46, whereas specificity remained high (0.95). For checklist and interview, strong associations were found between FH-MDD+ and most depressive symptoms and MDD diagnosis (all odds ratio≥1.83). The self-administered checklist showed high reliability for both the assessment of lifetime depressive symptoms and screening for individuals with no lifetime diagnosis of MDD. However, attention is warranted when the aim is to identify MDD cases. The positive association between depressive symptomatology and FH-MDD+ indicates the usefulness of both instruments to assess patients in genetic studies. Our data suggest that the more time-efficient and cost-efficient self-administered instruments also allow for the assessment of depressive symptoms accurate enough to investigate the influence of MDD genetic risk

Expert and self-assessment of lifetime symptoms and diagnosis of major depressive disorder in large-scale genetic studies in the general population: comparison of a clinical interview and a self-administered checklist

PubMed Central

Martin, Jessica; Streit, Fabian; Treutlein, Jens; Lang, Maren; Frank, Josef; Forstner, Andreas J.; Degenhardt, Franziska; Witt, Stephanie H.; Schulze, Thomas G.; Cichon, Sven; Nöthen, Markus M.; Rietschel, Marcella

2017-01-01

Major depression disorder (MDD) is a complex neuropsychiatric disorder and an increasing number of genetic risk variants are being identified. Investigation of their influence in the general population requires accurate and efficient assessment of depressive symptoms. Here, clinical interviews conducted by clinicians are the gold standard. We investigated whether valid and reliable clinical phenotypes can be obtained efficiently using self-administered instruments. Lifetime depressive symptoms and lifetime MDD diagnosis were assessed in 464 population-based individuals using a clinical interview and a structured, self-administered checklist. Analyses were carried out of the following: (i) intraclass correlations (ICC) between checklist and interview; (ii) sensitivity/specificity of the checklist; and (iii) the association of interview and checklist with a positive family history of MDD (FH-MDD+). The correspondence of the self-administered checklist with the clinical interview was good for most depressive symptoms (ICC=0.60–0.80) and moderate for MDD diagnosis (ICC=0.45). With the consecutive inclusion of MDD diagnostic criteria, sensitivity decreased from 0.67 to 0.46, whereas specificity remained high (0.95). For checklist and interview, strong associations were found between FH-MDD+ and most depressive symptoms and MDD diagnosis (all odds ratio≥1.83). The self-administered checklist showed high reliability for both the assessment of lifetime depressive symptoms and screening for individuals with no lifetime diagnosis of MDD. However, attention is warranted when the aim is to identify MDD cases. The positive association between depressive symptomatology and FH-MDD+ indicates the usefulness of both instruments to assess patients in genetic studies. Our data suggest that the more time-efficient and cost-efficient self-administered instruments also allow for the assessment of depressive symptoms accurate enough to investigate the influence of MDD genetic risk

Slapping and spanking in childhood and its association with lifetime prevalence of psychiatric disorders in a general population sample.

PubMed

MacMillan, H L; Boyle, M H; Wong, M Y; Duku, E K; Fleming, J E; Walsh, C A

1999-10-05

Little information is available in Canada about the prevalence of and outcomes associated with a history of slapping and spanking in childhood. The objectives of this study were to estimate the prevalence of a history of slapping or spanking in a general population sample and to assess the relation between such a history and the lifetime prevalence of psychiatric disorders. In this general population survey, a probability sample of 9953 residents of Ontario aged 15 years and older who participated in the Ontario Health Supplement was used to examine the prevalence of a history of slapping and spanking. A subgroup of this sample (n = 4888), which comprised people aged 15 to 64 years who did not report a history of physical or sexual abuse during childhood, was used to assess the relation between a history of slapping or spanking and the lifetime prevalence of 4 categories of psychiatric disorder. The measures included a self-administered questionnaire with a question about frequency of slapping and spanking during childhood, as well as an interviewer-administered questionnaire to measure psychiatric disorder. The majority of respondents indicated that they had been slapped or spanked, or both, by an adult during childhood "sometimes" (33.4%) or "rarely" (40.9%); 5.5% reported that this occurred "often." The remainder (20.2%) reported "never" experiencing these behaviours. Among the respondents without a history of physical or sexual abuse during childhood, those who reported being slapped or spanked "often" or "sometimes" had significantly higher lifetime rates of anxiety disorders (adjusted odds ratio [OR] 1.43, 95% confidence interval [CI] 1.04-1.96), alcohol abuse or dependence (adjusted OR 2.02, 95% CI 1.27-3.21) and one or more externalizing problems (adjusted OR 2.08, 95% CI 1.36-3.16), compared with those who reported "never" being slapped or spanked. There was also an association between a history of slapping or spanking and major depression, but it was not

Slapping and spanking in childhood and its association with lifetime prevalence of psychiatric disorders in a general population sample

PubMed Central

MacMillan, H L; Boyle, M H; Wong, M Y; Duku, E K; Fleming, J E; Walsh, C A

1999-01-01

BACKGROUND: Little information is available in Canada about the prevalence of and outcomes associated with a history of slapping and spanking in childhood. The objectives of this study were to estimate the prevalence of a history of slapping or spanking in a general population sample and to assess the relation between such a history and the lifetime prevalence of psychiatric disorders. METHODS: In this general population survey, a probability sample of 9953 residents of Ontario aged 15 years and older who participated in the Ontario Health Supplement was used to examine the prevalence of a history of slapping and spanking. A subgroup of this sample (n = 4888), which comprised people aged 15 to 64 years who did not report a history of physical or sexual abuse during childhood, was used to assess the relation between a history of slapping or spanking and the lifetime prevalence of 4 categories of psychiatric disorder. The measures included a self-administered questionnaire with a question about frequency of slapping and spanking during childhood, as well as an interviewer-administered questionnaire to measure psychiatric disorder. RESULTS: The majority of respondents indicated that they had been slapped or spanked, or both, by an adult during childhood "sometimes" (33.4%) or "rarely" (40.9%); 5.5% reported that this occurred "often." The remainder (20.2%) reported "never" experiencing these behaviours. Among the respondents without a history of physical or sexual abuse during childhood, those who reported being slapped or spanked "often" or "sometimes" had significantly higher lifetime rates of anxiety disorders (adjusted odds ratio [OR] 1.43, 95% confidence interval [CI] 1.04-1.96), alcohol abuse or dependence (adjusted OR 2.02, 95% CI 1.27-3.21) and one or more externalizing problems (adjusted OR 2.08, 95% CI 1.36-3.16), compared with those who reported "never" being slapped or spanked. There was also an association between a history of slapping or spanking and

Projected lifetime risks and hospital care expenditure for traumatic injury.

PubMed

Chang, David C; Anderson, Jamie E; Kobayashi, Leslie; Coimbra, Raul; Bickler, Stephen W

2012-08-01

The lifetime risk and expected cost of trauma care would be valuable for health policy planners, but this information is currently unavailable. The cumulative incidence rates methodology, based on a cross-sectional population analysis, offers an alternative approach to prohibitively costly prospective cohort studies. Retrospective analysis of the California Office of Statewide Health Planning and Development (OSHPD) database was performed for 2008. Trauma admissions were identified by ICD-9 primary diagnosis codes 800-959, with certain exclusions. Cumulative incidence rates were calculated as the cumulative summation of incidence risks sequentially across age groups. A total of 2.2 million admissions were identified, with mean age of 63.8 y, 49.6% men, 82.8% Whites, 5.7% Blacks, 11.3% Hispanics, and 3.1% Asians. The cumulative incidence rate for patients older than age 85 y was 1119 per 10,000 people, with the majority of risk in the elderly, compared with 24,325 per 10,000 people for all-cause hospitalizations. The rates were 946 for men, 1079 for women, 999 for non-Hispanic Whites, 568 for Blacks, 577 for Hispanics, and 395 for Asians, per 10,000 population. The cumulative expected hospital charge was $6538, compared with $81,257 for all-cause hospitalizations. The cumulative lifetime risk of trauma/injury requiring hospitalization for a person living to age 85 y in California is 11.2%, accounting for 4.6% of expected lifetime hospitalizations, but accounting for 8.0% of expected lifetime hospital expenditures. Risk of trauma is significant in the elderly. The total expenditure for all trauma hospitalizations in California was $7.62 billion in 2008. Copyright © 2012 Elsevier Inc. All rights reserved.

Visual Basic, Excel-based fish population modeling tool - The pallid sturgeon example

USGS Publications Warehouse

Moran, Edward H.; Wildhaber, Mark L.; Green, Nicholas S.; Albers, Janice L.

2016-02-10

The model presented in this report is a spreadsheet-based model using Visual Basic for Applications within Microsoft Excel (http://dx.doi.org/10.5066/F7057D0Z) prepared in cooperation with the U.S. Army Corps of Engineers and U.S. Fish and Wildlife Service. It uses the same model structure and, initially, parameters as used by Wildhaber and others (2015) for pallid sturgeon. The difference between the model structure used for this report and that used by Wildhaber and others (2015) is that variance is not partitioned. For the model of this report, all variance is applied at the iteration and time-step levels of the model. Wildhaber and others (2015) partition variance into parameter variance (uncertainty about the value of a parameter itself) applied at the iteration level and temporal variance (uncertainty caused by random environmental fluctuations with time) applied at the time-step level. They included implicit individual variance (uncertainty caused by differences between individuals) within the time-step level.The interface developed for the model of this report is designed to allow the user the flexibility to change population model structure and parameter values and uncertainty separately for every component of the model. This flexibility makes the modeling tool potentially applicable to any fish species; however, the flexibility inherent in this modeling tool makes it possible for the user to obtain spurious outputs. The value and reliability of the model outputs are only as good as the model inputs. Using this modeling tool with improper or inaccurate parameter values, or for species for which the structure of the model is inappropriate, could lead to untenable management decisions. By facilitating fish population modeling, this modeling tool allows the user to evaluate a range of management options and implications. The goal of this modeling tool is to be a user-friendly modeling tool for developing fish population models useful to natural resource

Designing a Community-Based Population Health Model.

PubMed

Durovich, Christopher J; Roberts, Peter W

2018-02-01

The pace of change from volume-based to value-based payment in health care varies dramatically among markets. Regardless of the ultimate disposition of the Affordable Care Act, employers and public-private payers will continue to increase pressure on health care providers to assume financial risk for populations in the form of shared savings, bundled payments, downside risk, or even capitation. This article outlines a suggested road map and practical considerations for health systems that are building or planning to build population health capabilities to meet the needs of their local markets. The authors review the traditional core capabilities needed to address the medical determinants of health for a population. They also share an innovative approach to community service integration to address the social determinants of health and the engagement of families to improve their own health and well-being. The foundational approach is to connect insurance products, the health care delivery system, and community service agencies around the family's well-being goals using human-centered design strategy.

Modeling the population-level effects of hypoxia on a coastal fish: implications of a spatially-explicit individual-based model

NASA Astrophysics Data System (ADS)

Rose, K.; Creekmore, S.; Thomas, P.; Craig, K.; Neilan, R.; Rahman, S.; Wang, L.; Justic, D.

2016-02-01

The northwestern Gulf of Mexico (USA) currently experiences a large hypoxic area ("dead zone") during the summer. The population-level effects of hypoxia on coastal fish are largely unknown. We developed a spatially-explicit, individual-based model to analyze how hypoxia effects on reproduction, growth, and mortality of individual Atlantic croaker could lead to population-level responses. The model follows the hourly growth, mortality, reproduction, and movement of individuals on a 300 x 800 spatial grid of 1 km2 cells for 140 years. Chlorophyll-a concentration and water temperature were specified daily for each grid cell. Dissolved oxygen (DO) was obtained from a 3-D water quality model for four years that differed in their severity of hypoxia. A bioenergetics model was used to represent growth, mortality was assumed stage- and age-dependent, and movement behavior was based on temperature preferences and avoidance of low DO. Hypoxia effects were imposed using exposure-effects sub-models that converted time-varying exposure to DO to reductions in growth and fecundity, and increases in mortality. Using sequences of mild, intermediate, and severe hypoxia years, the model predicted a 20% decrease in population abundance. Additional simulations were performed under the assumption that river-based nutrients loadings that lead to more hypoxia also lead to higher primary production and more food for croaker. Twenty-five percent and 50% nutrient reduction scenarios were simulated by adjusting the cholorphyll-a concentrations used as food proxy for the croaker. We then incrementally increased the DO concentrations to determine how much hypoxia would need to be reduced to offset the lower food production resulting from reduced nutrients. We discuss the generality of our results, the hidden effects of hypoxia on fish, and our overall strategy of combining laboratory and field studies with modeling to produce robust predictions of population responses to stressors under

Exits in order: How crowding affects particle lifetimes

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

Penington, Catherine J.; Simpson, Matthew J.; Baker, Ruth E.

2016-06-28

Diffusive processes are often represented using stochastic random walk frameworks. The amount of time taken for an individual in a random walk to intersect with an absorbing boundary is a fundamental property that is often referred to as the particle lifetime, or the first passage time. The mean lifetime of particles in a random walk model of diffusion is related to the amount of time required for the diffusive process to reach a steady state. Mathematical analysis describing the mean lifetime of particles in a standard model of diffusion without crowding is well known. However, the lifetime of agents inmore » a random walk with crowding has received much less attention. Since many applications of diffusion in biology and biophysics include crowding effects, here we study a discrete model of diffusion that incorporates crowding. Using simulations, we show that crowding has a dramatic effect on agent lifetimes, and we derive an approximate expression for the mean agent lifetime that includes crowding effects. Our expression matches simulation results very well, and highlights the importance of crowding effects that are sometimes overlooked.« less

Population-expression models of immune response

NASA Astrophysics Data System (ADS)

Stromberg, Sean P.; Antia, Rustom; Nemenman, Ilya

2013-06-01

The immune response to a pathogen has two basic features. The first is the expansion of a few pathogen-specific cells to form a population large enough to control the pathogen. The second is the process of differentiation of cells from an initial naive phenotype to an effector phenotype which controls the pathogen, and subsequently to a memory phenotype that is maintained and responsible for long-term protection. The expansion and the differentiation have been considered largely independently. Changes in cell populations are typically described using ecologically based ordinary differential equation models. In contrast, differentiation of single cells is studied within systems biology and is frequently modeled by considering changes in gene and protein expression in individual cells. Recent advances in experimental systems biology make available for the first time data to allow the coupling of population and high dimensional expression data of immune cells during infections. Here we describe and develop population-expression models which integrate these two processes into systems biology on the multicellular level. When translated into mathematical equations, these models result in non-conservative, non-local advection-diffusion equations. We describe situations where the population-expression approach can make correct inference from data while previous modeling approaches based on common simplifying assumptions would fail. We also explore how model reduction techniques can be used to build population-expression models, minimizing the complexity of the model while keeping the essential features of the system. While we consider problems in immunology in this paper, we expect population-expression models to be more broadly applicable.

Uncertainties in models of tropospheric ozone based on Monte Carlo analysis: Tropospheric ozone burdens, atmospheric lifetimes and surface distributions

NASA Astrophysics Data System (ADS)

Derwent, Richard G.; Parrish, David D.; Galbally, Ian E.; Stevenson, David S.; Doherty, Ruth M.; Naik, Vaishali; Young, Paul J.

2018-05-01

Recognising that global tropospheric ozone models have many uncertain input parameters, an attempt has been made to employ Monte Carlo sampling to quantify the uncertainties in model output that arise from global tropospheric ozone precursor emissions and from ozone production and destruction in a global Lagrangian chemistry-transport model. Ninety eight quasi-randomly Monte Carlo sampled model runs were completed and the uncertainties were quantified in tropospheric burdens and lifetimes of ozone, carbon monoxide and methane, together with the surface distribution and seasonal cycle in ozone. The results have shown a satisfactory degree of convergence and provide a first estimate of the likely uncertainties in tropospheric ozone model outputs. There are likely to be diminishing returns in carrying out many more Monte Carlo runs in order to refine further these outputs. Uncertainties due to model formulation were separately addressed using the results from 14 Atmospheric Chemistry Coupled Climate Model Intercomparison Project (ACCMIP) chemistry-climate models. The 95% confidence ranges surrounding the ACCMIP model burdens and lifetimes for ozone, carbon monoxide and methane were somewhat smaller than for the Monte Carlo estimates. This reflected the situation where the ACCMIP models used harmonised emissions data and differed only in their meteorological data and model formulations whereas a conscious effort was made to describe the uncertainties in the ozone precursor emissions and in the kinetic and photochemical data in the Monte Carlo runs. Attention was focussed on the model predictions of the ozone seasonal cycles at three marine boundary layer stations: Mace Head, Ireland, Trinidad Head, California and Cape Grim, Tasmania. Despite comprehensively addressing the uncertainties due to global emissions and ozone sources and sinks, none of the Monte Carlo runs were able to generate seasonal cycles that matched the observations at all three MBL stations. Although

How shorter black carbon lifetime alters its climate effect.

PubMed

Hodnebrog, Øivind; Myhre, Gunnar; Samset, Bjørn H

2014-09-25

Black carbon (BC), unlike most aerosol types, absorbs solar radiation. However, the quantification of its climate impact is uncertain and presently under debate. Recently, attention has been drawn both to a likely underestimation of global BC emissions in climate models, and an overestimation of BC at high altitudes. Here we show that doubling present day BC emissions in a model simulation, while reducing BC lifetime based on observational evidence, leaves the direct aerosol effect of BC virtually unchanged. Increased emissions, together with increased wet removal that reduces the lifetime, yields modelled BC vertical profiles that are in strongly improved agreement with recent aircraft observations. Furthermore, we explore the consequences of an altered BC profile in a global circulation model, and show that both the vertical profile of BC and rapid climate adjustments need to be taken into account in order to assess the total climate impact of BC.

Cost-Effectiveness of Orthogeriatric and Fracture Liaison Service Models of Care for Hip Fracture Patients: A Population-Based Study.

PubMed

Leal, Jose; Gray, Alastair M; Hawley, Samuel; Prieto-Alhambra, Daniel; Delmestri, Antonella; Arden, Nigel K; Cooper, Cyrus; Javaid, M Kassim; Judge, Andrew

2017-02-01

Fracture liaison services are recommended as a model of best practice for organizing patient care and secondary fracture prevention for hip fracture patients, although variation exists in how such services are structured. There is considerable uncertainty as to which model is most cost-effective and should therefore be mandated. This study evaluated the cost- effectiveness of orthogeriatric (OG)- and nurse-led fracture liaison service (FLS) models of post-hip fracture care compared with usual care. Analyses were conducted from a health care and personal social services payer perspective, using a Markov model to estimate the lifetime impact of the models of care. The base-case population consisted of men and women aged 83 years with a hip fracture. The risk and costs of hip and non-hip fractures were derived from large primary and hospital care data sets in the UK. Utilities were informed by a meta-regression of 32 studies. In the base-case analysis, the orthogeriatric-led service was the most effective and cost-effective model of care at a threshold of £30,000 per quality-adjusted life years gained (QALY). For women aged 83 years, the OG-led service was the most cost-effective at £22,709/QALY. If only health care costs are considered, OG-led service was cost-effective at £12,860/QALY and £14,525/QALY for women and men aged 83 years, respectively. Irrespective of how patients were stratified in terms of their age, sex, and Charlson comorbidity score at index hip fracture, our results suggest that introducing an orthogeriatrician-led or a nurse-led FLS is cost-effective when compared with usual care. Although considerable uncertainty remains concerning which of the models of care should be preferred, introducing an orthogeriatrician-led service seems to be the most cost-effective service to pursue. © 2016 American Society for Bone and Mineral Research. © 2016 American Society for Bone and Mineral Research.

Societal and Family Lifetime Cost of Dementia: Implications for Policy.

PubMed

Jutkowitz, Eric; Kane, Robert L; Gaugler, Joseph E; MacLehose, Richard F; Dowd, Bryan; Kuntz, Karen M

2017-10-01

To estimate the cost of dementia and the extra cost of caring for someone with dementia over the cost of caring for someone without dementia. We developed an evidence-based mathematical model to simulate disease progression for newly diagnosed individuals with dementia. Data-driven trajectories of cognition, function, and behavioral and psychological symptoms were used to model disease progression and predict costs. Using modeling, we evaluated lifetime and annual costs of individuals with dementia, compared costs of those with and without clinical features of dementia, and evaluated the effect of reducing functional decline or behavioral and psychological symptoms by 10% for 12 months (implemented when Mini-Mental State Examination score ≤21). Mathematical model. Representative simulated U.S. incident dementia cases. Value of informal care, out-of-pocket expenditures, Medicaid expenditures, and Medicare expenditures. From time of diagnosis (mean age 83), discounted total lifetime cost of care for a person with dementia was $321,780 (2015 dollars). Families incurred 70% of the total cost burden ($225,140), Medicaid accounted for 14% ($44,090), and Medicare accounted for 16% ($52,540). Costs for a person with dementia over a lifetime were $184,500 greater (86% incurred by families) than for someone without dementia. Total annual cost peaked at $89,000, and net cost peaked at $72,400. Reducing functional decline or behavioral and psychological symptoms by 10% resulted in $3,880 and $680 lower lifetime costs than natural disease progression. Dementia substantially increases lifetime costs of care. Long-lasting, effective interventions are needed to support families because they incur the most dementia cost. © 2017, Copyright the Authors Journal compilation © 2017, The American Geriatrics Society.

Kinetic approach to degradation mechanisms in polymer solar cells and their accurate lifetime predictions

NASA Astrophysics Data System (ADS)

Arshad, Muhammad Azeem; Maaroufi, AbdelKrim

2018-07-01

A beginning has been made in the present study regarding the accurate lifetime predictions of polymer solar cells. Certain reservations about the conventionally employed temperature accelerated lifetime measurements test for its unworthiness of predicting reliable lifetimes of polymer solar cells are brought into light. Critical issues concerning the accelerated lifetime testing include, assuming reaction mechanism instead of determining it, and relying solely on the temperature acceleration of a single property of material. An advanced approach comprising a set of theoretical models to estimate the accurate lifetimes of polymer solar cells is therefore suggested in order to suitably alternate the accelerated lifetime testing. This approach takes into account systematic kinetic modeling of various possible polymer degradation mechanisms under natural weathering conditions. The proposed kinetic approach is substantiated by its applications on experimental aging data-sets of polymer solar materials/solar cells including, P3HT polymer film, bulk heterojunction (MDMO-PPV:PCBM) and dye-sensitized solar cells. Based on the suggested approach, an efficacious lifetime determination formula for polymer solar cells is derived and tested on dye-sensitized solar cells. Some important merits of the proposed method are also pointed out and its prospective applications are discussed.

Organism and population-level ecological models for ...

EPA Pesticide Factsheets

Ecological risk assessment typically focuses on animal populations as endpoints for regulatory ecotoxicology. Scientists at USEPA are developing models for animal populations exposed to a wide range of chemicals from pesticides to emerging contaminants. Modeled taxa include aquatic and terrestrial invertebrates, fish, amphibians, and birds, and employ a wide range of methods, from matrix-based projection models to mechanistic bioenergetics models and spatially explicit population models. not applicable

A parallel implementation of an off-lattice individual-based model of multicellular populations

NASA Astrophysics Data System (ADS)

Harvey, Daniel G.; Fletcher, Alexander G.; Osborne, James M.; Pitt-Francis, Joe

2015-07-01

As computational models of multicellular populations include ever more detailed descriptions of biophysical and biochemical processes, the computational cost of simulating such models limits their ability to generate novel scientific hypotheses and testable predictions. While developments in microchip technology continue to increase the power of individual processors, parallel computing offers an immediate increase in available processing power. To make full use of parallel computing technology, it is necessary to develop specialised algorithms. To this end, we present a parallel algorithm for a class of off-lattice individual-based models of multicellular populations. The algorithm divides the spatial domain between computing processes and comprises communication routines that ensure the model is correctly simulated on multiple processors. The parallel algorithm is shown to accurately reproduce the results of a deterministic simulation performed using a pre-existing serial implementation. We test the scaling of computation time, memory use and load balancing as more processes are used to simulate a cell population of fixed size. We find approximate linear scaling of both speed-up and memory consumption on up to 32 processor cores. Dynamic load balancing is shown to provide speed-up for non-regular spatial distributions of cells in the case of a growing population.

Recoil Distance Method lifetime measurements via gamma-ray and charged-particle spectroscopy at NSCL

NASA Astrophysics Data System (ADS)

Voss, Philip Jonathan

The Recoil Distance Method (RDM) is a well-established technique for measuring lifetimes of electromagnetic transitions. Transition matrix elements derived from the lifetimes provide valuable insight into nuclear structure. Recent RDM investigations at NSCL present a powerful new model-independent tool for the spectroscopy of nuclei with extreme proton-to-neutron ratios that exhibit surprising behavior. Neutron-rich 18C is one such example, where a small B(E2; 2+1 → 0+gs) represented a dramatic shift from the expected inverse relationship between the B(E2) and 2+1 excitation energy. To shed light on the nature of this quadrupole excitation, the RDM lifetime technique was applied with the Koln/NSCL plunger. States in 18C were populated by the one-proton knockout reaction of a 19N secondary beam. De-excitation gamma rays were detected with the Segmented Germanium Array in coincidence with reaction residues at the focal plane of the S800 Magnetic Spectrometer. The deduced B(E2) and excitation energy were both well described by ab initio no-core shell model calculations. In addition, a novel extension of RDM lifetime measurements via charged-particle spectroscopy of exotic proton emitters has been investigated. Substituting the reaction residue degrader of the Koln/NSCL plunger with a thin silicon detector permits the study of short-lived nuclei beyond the proton dripline. A proof of concept measurement of the mean lifetime of the two-proton emitter 19Mg was conducted. The results indicated a sub-picosecond lifetime, one order of magnitude smaller than the published results, and validate this new technique for lifetime measurements of charged-particle emitters.

The lifetime risk of maternal mortality: concept and measurement

PubMed Central

2009-01-01

Abstract Objective The lifetime risk of maternal mortality, which describes the cumulative loss of life due to maternal deaths over the female life course, is an important summary measure of population health. However, despite its interpretive appeal, the lifetime risk of dying from maternal causes can be defined and calculated in various ways. A clear and concise discussion of both its underlying concept and methods of measurement is badly needed. Methods I define and compare a variety of procedures for calculating the lifetime risk of maternal mortality. I use detailed survey data from Bangladesh in 2001 to illustrate these calculations and compare the properties of the various risk measures. Using official UN estimates of maternal mortality for 2005, I document the differences in lifetime risk derived with the various measures. Findings Taking sub-Saharan Africa as an example, the range of estimates for the 2005 lifetime risk extends from 3.41% to 5.76%, or from 1 in 29 to 1 in 17. The highest value resulted from the method used for producing official UN estimates for the year 2000. The measure recommended here has an intermediate value of 4.47%, or 1 in 22. Conclusion There are strong reasons to consider the calculation method proposed here more accurate and appropriate than earlier procedures. Accordingly, it was adopted for use in producing the 2005 UN estimates of the lifetime risk of maternal mortality. By comparison, the method used for the 2000 UN estimates appears to overestimate this important measure of population health by around 20%. PMID:19551233

Gun violence in Americans' social network during their lifetime.

PubMed

Kalesan, Bindu; Weinberg, Janice; Galea, Sandro

2016-12-01

The overall burden of gun violence death and injury in the US is now well understood. However, no study has shown the extent to which gun violence is associated with the individual lives of Americans. We used fatal and non-fatal gun injury rates in 2013 from Centers for Disease Control and Prevention's Web-based Injury Statistics Query and Reporting System (WISQARS) and generally accepted estimates about the size of an American's social network to determine the likelihood that any given person will know someone in their personal social network who is a victim of gun violence during their lifetime. We derived estimates in the overall population and among racial/ethnic groups and by gun-injury intent. The likelihood of knowing a gun violence victim within any given personal network over a lifetime is 99.85% (99.8% to 99.9%). The likelihood among non-Hispanic white, black, Hispanic and other race Americans were 97.1%, 99.9%, 99.5% and 88.9% respectively. Nearly all Americans of all racial/ethnic groups are likely to know a victim of gun violence in their social network during their lifetime. Copyright © 2016 Elsevier Inc. All rights reserved.

Prevalence and Trends in Lifetime Obesity in the U.S., 1988-2014.

PubMed

Stokes, Andrew; Ni, Yu; Preston, Samuel H

2017-11-01

Estimates of obesity prevalence based on current BMI are an important but incomplete indicator of the total effects of obesity on a population. In this study, data on current BMI and maximum BMI were used to estimate prevalence and trends in lifetime obesity status, defined using the categories never (maximum BMI ≤30 kg/m 2 ), former (maximum BMI ≥30 kg/m 2 and current BMI ≤30 kg/m 2 ), and current obesity (current BMI ≥30 kg/m 2 ). Prevalence was estimated for the period 2013-2014 and trends for the period 1988-2014 using data from the National Health and Nutrition Examination Survey. Predictors of lifetime weight status and the association between lifetime weight categories and prevalent disease status were also investigated using multivariable regression. A total of 50.8% of American males and 51.6% of American females were ever obese in 2013-2014. The prevalence of lifetime obesity exceeded the prevalence of current obesity by amounts that were greater for males and for older persons. The gap between the two prevalence values has risen over time. By 2013-2014, a total of 22.0% of individuals who were not currently obese had formerly been obese. For each of eight diseases considered, prevalence was higher among the formerly obese than among the never obese. A larger fraction of the population is affected by obesity and its health consequences than is suggested in prior studies based on current BMI alone. Weight history should be incorporated into routine health surveillance of the obesity epidemic for a full accounting of the effects of obesity on the U.S. Copyright © 2017 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

Probabilistic estimation of residential air exchange rates for population-based human exposure modeling

EPA Science Inventory

Residential air exchange rates (AERs) are a key determinant in the infiltration of ambient air pollution indoors. Population-based human exposure models using probabilistic approaches to estimate personal exposure to air pollutants have relied on input distributions from AER meas...

Occupational risk factors for chronic respiratory disease in a New Zealand population using lifetime occupational history.

PubMed

Hansell, Anna; Ghosh, Rebecca E; Poole, Suzanne; Zock, Jan-Paul; Weatherall, Mark; Vermeulen, Roel; Kromhout, Hans; Travers, Justin; Beasley, Richard

2014-03-01

To investigate associations between respiratory disease and occupational exposures in a New Zealand urban population, the Wellington Respiratory Survey. Multiple regression analyses in a population sample of 1017 individuals aged 25 to 74 years with spirometry and questionnaire information, including a lifetime occupational history. Chronic bronchitis symptoms were associated with self-reported exposure to hairdressing, paint manufacturing, insecticides, welding, detergents and with ALOHA Job Exposure Matrix-assessed gases/fumes exposure. The strongest association was for hairdressing (odds ratio 6.91; 95% confidence interval: 2.02 to 23.70). Cumulative exposure to mineral dust and gases/fumes was associated with higher FEV₁% (forced expiratory volume in the first second of expiration) predicted. Analyses were limited by relatively small numbers of cases. Increased risks of objectively defined respiratory disease, which have been previously documented, were not seen. Nevertheless, the study suggested increased risk of respiratory symptoms with various occupational exposures as well as likely healthy worker effect.

Development of Next Generation Lifetime PSP Imaging Systems

NASA Technical Reports Server (NTRS)

Watkins, A. Neal; Jordan, Jeffrey D.; Leighty, Bradley D.; Ingram, JoAnne L.; Oglesby, Donald M.

2002-01-01

This paper describes a lifetime PSP system that has recently been developed using pulsed light-emitting diode (LED) lamps and a new interline transfer CCD camera technology. This system alleviates noise sources associated with lifetime PSP systems that use either flash-lamp or laser excitation sources and intensified CCD cameras for detection. Calibration curves have been acquired for a variety of PSP formulations using this system, and a validation test was recently completed in the Subsonic Aerodynamic Research Laboratory (SARL) at Wright-Patterson Air Force Base (WPAFB). In this test, global surface pressure distributions were recovered using both a standard intensity-based method and the new lifetime system. Results from the lifetime system agree both qualitatively and quantitatively with those measured using the intensity-based method. Finally, an advanced lifetime imaging technique capable of measuring temperature and pressure simultaneously is introduced and initial results are presented.

The association of lifetime physical inactivity with bladder and renal cancer risk: A hospital-based case-control analysis.

PubMed

Cannioto, Rikki; Etter, John Lewis; Guterman, Lauren Beryl; Joseph, Janine M; Gulati, Nicholas R; Schmitt, Kristina L; LaMonte, Michael J; Nagy, Ryan; Minlikeeva, Albina; Szender, James Brian; Moysich, Kirsten B

2017-08-01

Recreational physical inactivity has been gaining recognition as an independent epidemiological exposure of interest in relation to cancer endpoints due to evidence suggesting that it may associate with cancer independent of obesity. In the current analyses, we examined the associations of lifetime recreational physical inactivity with renal and bladder cancer risk. In this hospital-based case-control study, we identified N=160 renal cancer patients, N=208 bladder cancer patients, and N=766 age frequency-matched controls without cancer. Participants self-reporting never participating in any regular/weekly recreational physical activity throughout their lifetime were classified as physically inactive. Utilizing unconditional multivariable logistic regression analyses, we estimated odds ratios and 95% confidence intervals to represent the associations between lifetime physical inactivity and renal and bladder cancer risk. In multivariable logistic regression models, we observed significant positive associations between lifetime recreational physical inactivity and renal cancer and bladder cancer risk: odds ratio=1.77 (95% CI: 1.10-2.85) and odds ratio=1.73 (95% CI: 1.13-2.63), respectively. Similar associations also persisted among individuals who were not obese for both renal and bladder cancer: odds ratio=1.75 (95% CI: 1.03-2.98) and odds ratio=1.70 (95% CI: 1.08-2.69), respectively. In this case-control study, we observed evidence of a positive association between renal and bladder cancer with lifetime recreational physical inactivity. These data add to the growing body of evidence suggesting that physical inactivity may be an important independent risk factor for cancer. However, additional studies using a larger sample and prospectively collected data are needed to substantiate the current findings. Copyright © 2017 Elsevier Ltd. All rights reserved.

Continued Analysis of the NIST Neutron Lifetime Measurement Using Ultracold Neutrons

NASA Astrophysics Data System (ADS)

Huffer, Craig; Huffman, P. R.; Schelhammer, K. W.; Dewey, M. S.; Huber, M. G.; Hughes, P. P.; Mumm, H. P.; Thompson, A. K.; Coakley, K.; Yue, A. T.; O'Shaughnessy, C. M.; Yang, L.

2013-10-01

The neutron lifetime is an important parameter for constraining the Standard Model and providing input for Big Bang Nucleosynthesis. The current disagreement in the most recent generation of lifetime experiments suggests unknown or underestimated systematics and motivates the need for alternative measurement methods as well as additional investigations into potential systematics. Our measurement was performed using magnetically trapped Ultracold Neutrons in a 3.1 T Ioffe type trap configuration. The decay rate of the neutron population is recorded in real time by monitoring visible light resulting from beta decay. Data collected in late 2010 and early 2011 is being analyzed and systematic effects are being investigated. An overview of our current work on the analysis, Monte Carlo simulations, and systematic effects will be provided. This work was supported by the NSF and NIST.

Variation in Adenoma Detection Rate and the Lifetime Benefits and Cost of Colorectal Cancer Screening: A Microsimulation Model

PubMed Central

Meester, Reinier G.S.; Doubeni, Chyke A.; Lansdorp-Vogelaar, Iris; Jensen, Christopher D.; van der Meulen, Miriam P.; Levin, Theodore R.; Quinn, Virginia P.; Schottinger, Joanne E.; Zauber, Ann G.; Corley, Douglas A.; van Ballegooijen, Marjolein

2015-01-01

IMPORTANCE Colonoscopy is the most commonly used colorectal cancer screening test in the United States. Its quality, as measured by adenoma detection rates, varies widely between physicians with unknown consequences for the cost and benefits of screening programs. OBJECTIVE To estimate the lifetime benefits, complications and costs of a colonoscopy screening program at different levels of adenoma detection. DESIGN, SETTING and PARTICIPANTS This study used microsimulation modeling with data from a community-based healthcare system on adenoma detection rate variation and cancer risk among 136 physicians and 57,588 patients for 1998–2010. EXPOSURE Using modeling, no screening was compared to screening initiation with colonoscopy according to adenoma detection rate quintiles (averages 15.3, 21.3, 25.6, 30.9, and 38.7%) at ages 50, 60 and 70 with appropriate surveillance of adenoma patients. MAIN OUTCOMES Estimated lifetime colorectal cancer incidence, mortality, number of colonoscopies, complications and costs per 1,000 patients, all discounted at 3% per year and including 95% confidence intervals from multiway probabilistic sensitivity analysis (95%CI). RESULTS In simulation modeling, among unscreened patients, the lifetime risks of colorectal cancer incidence and mortality were 34.2 (95%CI:25.9–43.6) and 13.4 (95%CI:10.0–17.6) per 1,000, respectively. Among screened patients, simulated lifetime incidence decreased with lower to higher adenoma detection rates (quintile 1 versus 5: 26.6, 95%CI:20.0–34.3 versus 12.5, 95%CI:9.3–16.5) as did mortality (5.7, 95%CI:4.2–7.7 versus 2.3, 95%CI:1.7–3.1). Compared to quintile 1, simulated lifetime incidence and mortality were on average 11.4% (95%CI:10.3–11.9) and 12.8% (95%CI:11.1–13.7) lower, respectively, for every 5 percentage-point higher adenoma detection rate. Total colonoscopies and associated complications were higher from quintile 1 (2,777, 95%CI:2,626–2,943 and 6.0, 95%CI:4.0–8.5) to subsequent

Filter replacement lifetime prediction

DOEpatents

Hamann, Hendrik F.; Klein, Levente I.; Manzer, Dennis G.; Marianno, Fernando J.

2017-10-25

Methods and systems for predicting a filter lifetime include building a filter effectiveness history based on contaminant sensor information associated with a filter; determining a rate of filter consumption with a processor based on the filter effectiveness history; and determining a remaining filter lifetime based on the determined rate of filter consumption. Methods and systems for increasing filter economy include measuring contaminants in an internal and an external environment; determining a cost of a corrosion rate increase if unfiltered external air intake is increased for cooling; determining a cost of increased air pressure to filter external air; and if the cost of filtering external air exceeds the cost of the corrosion rate increase, increasing an intake of unfiltered external air.

Comparison of individual-based modeling and population approaches for prediction of foodborne pathogens growth.

PubMed

Augustin, Jean-Christophe; Ferrier, Rachel; Hezard, Bernard; Lintz, Adrienne; Stahl, Valérie

2015-02-01

Individual-based modeling (IBM) approach combined with the microenvironment modeling of vacuum-packed cold-smoked salmon was more effective to describe the variability of the growth of a few Listeria monocytogenes cells contaminating irradiated salmon slices than the traditional population models. The IBM approach was particularly relevant to predict the absence of growth in 25% (5 among 20) of artificially contaminated cold-smoked salmon samples stored at 8 °C. These results confirmed similar observations obtained with smear soft cheese (Ferrier et al., 2013). These two different food models were used to compare the IBM/microscale and population/macroscale modeling approaches in more global exposure and risk assessment frameworks taking into account the variability and/or the uncertainty of the factors influencing the growth of L. monocytogenes. We observed that the traditional population models significantly overestimate exposure and risk estimates in comparison to IBM approach when contamination of foods occurs with a low number of cells (<100 per serving). Moreover, the exposure estimates obtained with the population model were characterized by a great uncertainty. The overestimation was mainly linked to the ability of IBM to predict no growth situations rather than the consideration of microscale environment. On the other hand, when the aim of quantitative risk assessment studies is only to assess the relative impact of changes in control measures affecting the growth of foodborne bacteria, the two modeling approach gave similar results and the simplest population approach was suitable. Copyright © 2014 Elsevier Ltd. All rights reserved.

Population-level analysis and validation of an individual-based cutthroat trout model

Treesearch

Steven F. Railsback; Bret C. Harvey; Roland H. Lamberson; Derek E. Lee; Claasen Nathan J.; Shuzo Yoshihara

2002-01-01

Abstract - An individual-based model of stream trout is analyzed by testing its ability to reproduce patterns of population-level behavior observed in real trout: (1) "self-thinning," a negative power relation between weight and abundance; (2) a "critical period" of density-dependent mortality in young-of-the-year; (3) high and age-speci...

The fiscal consequences of ADHD in Germany: a quantitative analysis based on differences in educational attainment and lifetime earnings.

PubMed

Kotsopoulos, Nikolaos; Connolly, Mark P; Sobanski, Esther; Postma, Maarten J

2013-03-01

To estimate the long-term fiscal consequences of attention deficit hyperactivity disorder (ADHD) on the German government and social insurance system based on differences in educational attainment and the resulting differences in lifetime earnings compared with non-ADHD cohorts. Differences in educational attainment between ADHD and non-ADHD cohorts were linked to education-specific earnings data. Direct and indirect tax rates and social insurance contributions were linked to differences in lifetime, education-specific earnings to derive lost tax revenue in Germany associated with ADHD. For ADHD and non-ADHD cohorts we derived the age-specific discounted net taxes paid by deducting lifetime transfers from lifetime gross taxes paid. The lifetime net tax revenue for a non-ADHD individual was approximately EUR 80,000 higher compared to an untreated ADHD individual. The fiscal burden of untreated ADHD, based on a cohort of n=31,844 born in 2010, was estimated at EUR 2.5 billion in net tax revenue losses compared with an equally-sized non-ADHD cohort. ADHD interventions providing a small improvement in educational attainment resulted in fiscal benefits from increases in lifetime tax gains. ADHD results in long-term financial loss due to lower education attainment and lifetime reduced earnings and resulting lifetime taxes and social contributions paid. Investments in ADHD interventions allowing more children to achieve their educational potential may offer fiscal benefits generating a positive rate of return.

A fast global fitting algorithm for fluorescence lifetime imaging microscopy based on image segmentation.

PubMed

Pelet, S; Previte, M J R; Laiho, L H; So, P T C

2004-10-01

Global fitting algorithms have been shown to improve effectively the accuracy and precision of the analysis of fluorescence lifetime imaging microscopy data. Global analysis performs better than unconstrained data fitting when prior information exists, such as the spatial invariance of the lifetimes of individual fluorescent species. The highly coupled nature of global analysis often results in a significantly slower convergence of the data fitting algorithm as compared with unconstrained analysis. Convergence speed can be greatly accelerated by providing appropriate initial guesses. Realizing that the image morphology often correlates with fluorophore distribution, a global fitting algorithm has been developed to assign initial guesses throughout an image based on a segmentation analysis. This algorithm was tested on both simulated data sets and time-domain lifetime measurements. We have successfully measured fluorophore distribution in fibroblasts stained with Hoechst and calcein. This method further allows second harmonic generation from collagen and elastin autofluorescence to be differentiated in fluorescence lifetime imaging microscopy images of ex vivo human skin. On our experimental measurement, this algorithm increased convergence speed by over two orders of magnitude and achieved significantly better fits. Copyright 2004 Biophysical Society

Fluorescence lifetime-based contrast enhancement of indocyanine green-labeled tumors

NASA Astrophysics Data System (ADS)

Kumar, Anand T. N.; Carp, Stefan A.; Yang, Jing; Ross, Alana; Medarova, Zdravka; Ran, Chongzhao

2017-04-01

Although the development of tumor-targeted fluorescent probes is a major area of investigation, it will be several years before these probes are realized for clinical use. Here, we report an approach that employs indocyanine-green (ICG), a clinically approved, nontargeted dye, in conjunction with fluorescence lifetime (FLT) detection to provide high accuracy for tumor-tissue identification in mouse models of subcutaneous human breast and brain tmors. The improved performance relies on the distinct FLTs of ICG within tumors versus tissue autofluorescence and is further aided by the well-known enhanced permeability and retention of ICG in tumors and the clearance of ICG from normal tissue several hours after intravenous injection. We demonstrate that FLT detection can provide more than 98% sensitivity and specificity, and a 10-fold reduction in error rates compared to intensity-based detection. Our studies suggest the significant potential of FLT-contrast for accurate tumor-tissue identification using ICG and other targeted probes under development, both for intraoperative imaging and for ex-vivo margin assessment of surgical specimens.

An individual-based model for population viability analysis of humpback chub in Grand Canyon

USGS Publications Warehouse

Pine, William Pine; Healy, Brian; Smith, Emily Omana; Trammell, Melissa; Speas, Dave; Valdez, Rich; Yard, Mike; Walters, Carl; Ahrens, Rob; Vanhaverbeke, Randy; Stone, Dennis; Wilson, Wade

2013-01-01

We developed an individual-based population viability analysis model (females only) for evaluating risk to populations from catastrophic events or conservation and research actions. This model tracks attributes (size, weight, viability, etc.) for individual fish through time and then compiles this information to assess the extinction risk of the population across large numbers of simulation trials. Using a case history for the Little Colorado River population of Humpback Chub Gila cypha in Grand Canyon, Arizona, we assessed extinction risk and resiliency to a catastrophic event for this population and then assessed a series of conservation actions related to removing specific numbers of Humpback Chub at different sizes for conservation purposes, such as translocating individuals to establish other spawning populations or hatchery refuge development. Our results suggested that the Little Colorado River population is generally resilient to a single catastrophic event and also to removals of larvae and juveniles for conservation purposes, including translocations to establish new populations. Our results also suggested that translocation success is dependent on similar survival rates in receiving and donor streams and low emigration rates from recipient streams. In addition, translocating either large numbers of larvae or small numbers of large juveniles has generally an equal likelihood of successful population establishment at similar extinction risk levels to the Little Colorado River donor population. Our model created a transparent platform to consider extinction risk to populations from catastrophe or conservation actions and should prove useful to managers assessing these risks for endangered species such as Humpback Chub.

Atmospheric drag model calibrations for spacecraft lifetime prediction

NASA Technical Reports Server (NTRS)

Binebrink, A. L.; Radomski, M. S.; Samii, M. V.

1989-01-01

Although solar activity prediction uncertainty normally dominates decay prediction error budget for near-Earth spacecraft, the effect of drag force modeling errors for given levels of solar activity needs to be considered. Two atmospheric density models, the modified Harris-Priester model and the Jacchia-Roberts model, to reproduce the decay histories of the Solar Mesosphere Explorer (SME) and Solar Maximum Mission (SMM) spacecraft in the 490- to 540-kilometer altitude range were analyzed. Historical solar activity data were used in the input to the density computations. For each spacecraft and atmospheric model, a drag scaling adjustment factor was determined for a high-solar-activity year, such that the observed annual decay in the mean semimajor axis was reproduced by an averaged variation-of-parameters (VOP) orbit propagation. The SME (SMM) calibration was performed using calendar year 1983 (1982). The resulting calibration factors differ by 20 to 40 percent from the predictions of the prelaunch ballistic coefficients. The orbit propagations for each spacecraft were extended to the middle of 1988 using the calibrated drag models. For the Jaccia-Roberts density model, the observed decay in the mean semimajor axis of SME (SMM) over the 4.5-year (5.5-year) predictive period was reproduced to within 1.5 (4.4) percent. The corresponding figure for the Harris-Priester model was 8.6 (20.6) percent. Detailed results and conclusions regarding the importance of accurate drag force modeling for lifetime predictions are presented.

Time-resolved fluorescence imaging of slab gels for lifetime base-calling in DNA sequencing applications.

PubMed

Lassiter, S J; Stryjewski, W; Legendre, B L; Erdmann, R; Wahl, M; Wurm, J; Peterson, R; Middendorf, L; Soper, S A

2000-11-01

A compact time-resolved near-IR fluorescence imager was constructed to obtain lifetime and intensity images of DNA sequencing slab gels. The scanner consisted of a microscope body with f/1.2 relay optics onto which was mounted a pulsed diode laser (repetition rate 80 MHz, lasing wavelength 680 nm, average power 5 mW), filtering optics, and a large photoactive area (diameter 500 microns) single-photon avalanche diode that was actively quenched to provide a large dynamic operating range. The time-resolved data were processed using electronics configured in a conventional time-correlated single-photon-counting format with all of the counting hardware situated on a PC card resident on the computer bus. The microscope head produced a timing response of 450 ps (fwhm) in a scanning mode, allowing the measurement of subnano-second lifetimes. The time-resolved microscope head was placed in an automated DNA sequencer and translated across a 21-cm-wide gel plate in approximately 6 s (scan rate 3.5 cm/s) with an accumulation time per pixel of 10 ms. The sampling frequency was 0.17 Hz (duty cycle 0.0017), sufficient to prevent signal aliasing during the electrophoresis separation. Software (written in Visual Basic) allowed acquisition of both the intensity image and lifetime analysis of DNA bands migrating through the gel in real time. Using a dual-labeling (IRD700 and Cy5.5 labeling dyes)/two-lane sequencing strategy, we successfully read 670 bases of a control M13mp18 ssDNA template using lifetime identification. Comparison of the reconstructed sequence with the known sequence of the phage indicated the number of miscalls was only 2, producing an error rate of approximately 0.3% (identification accuracy 99.7%). The lifetimes were calculated using maximum likelihood estimators and allowed on-line determinations with high precision, even when short integration times were used to construct the decay profiles. Comparison of the lifetime base calling to a single

Lifetime secondhand smoke exposure and childhood and adolescent asthma: findings from the PIAMA cohort.

PubMed

Milanzi, Edith B; Brunekreef, Bert; Koppelman, Gerard H; Wijga, Alet H; van Rossem, Lenie; Vonk, Judith M; Smit, Henriëtte A; Gehring, Ulrike

2017-02-23

Secondhand smoke (SHS) exposure is a modifiable risk factor associated with childhood asthma. Associations with adolescent asthma and the relevance of the timing and patterns of exposure are unclear. Knowledge of critical windows of exposure is important for targeted interventions. We used data until age 17 from 1454 children of the Dutch population-based PIAMA birth cohort. Residential SHS exposure was assessed through parental questionnaires completed at ages 3 months, 1-8 (yearly), 11, 14, and 17 years. Lifetime exposure was determined as; a) time window-specific exposure (prenatal, infancy, preschool, primary school, and secondary school); b) lifetime cumulative exposure; c) longitudinal exposure patterns using latent class growth modeling (LCGM). Generalized estimation equations and logistic regression were used to analyze associations between exposure and asthma at ages 4 to 17 years, adjusting for potential confounders. With all three methods, we consistently found no association between SHS exposure and asthma at ages 4 to 17 years e.g. adjusted overall odds ratio (95% confidence interval) 0.67 (0.41-1.12), 1.00 (0.66-1.51) and 0.67 (0.41-1.11) for prenatal maternal active smoking, infancy, and preschool school time window exposures, respectively. We assessed lifetime SHS exposure using different methods. Different timing and patterns of SHS exposure were not associated with an increased risk of asthma in childhood and adolescence in our study. More longitudinal studies could investigate effects of lifetime SHS exposure on asthma in adolescence and later life.

The impact of population aging on medical expenses: A big data study based on the life table.

PubMed

Wang, Changying; Li, Fen; Wang, Linan; Zhou, Wentao; Zhu, Bifan; Zhang, Xiaoxi; Ding, Lingling; He, Zhimin; Song, Peipei; Jin, Chunlin

2018-01-09

This study shed light on the amount and structure of utilization and medical expenses on Shanghai permanent residents based on big data, simulated lifetime medical expenses through combining of expenses data and life table model, and explored the dynamic pattern of aging on medical expenditures. 5 years were taken as the class interval, the study collected and did the descriptive analysis on the medical services utilization and medical expenses information for all ages of Shanghai permanent residents in 2015, simulated lifetime medical expenses by using current life table and cross-section expenditure data. The results showed that in 2015, outpatient and emergency visits per capita in the elderly group (aged 60 and over) was 4.1 and 4.5 times higher than the childhood group (aged 1-14), and the youth and adult group (aged 15-59); hospitalization per capita in the elderly group was 3.0 and 3.5 times higher than the childhood group, and the youth and adult group. People survived in the 60-64 years group, their expected whole medical expenses (105,447 purchasing power parity Dollar) in the rest of their lives accounted for 75.6% of their lifetime. A similar study in Michigan, US showed that the expenses of the population aged 65 and over accounted for 1/2 of lifetime medical expenses, which is much lower than Shanghai. The medical expenses of the advanced elderly group (aged 80 and over) accounted for 38.8% of their lifetime expenses, including 38.2% in outpatient and emergency, and 39.5% in hospitalization, which was slightly higher than outpatient and emergency. There is room to economize in medical expenditures of the elderly people in Shanghai, especially controlling hospitalization expenses is the key to saving medical expenses of elderly people aged over 80 and over.

Health Risk Factors Associated with Lifetime Abstinence from Alcohol in the 1979 National Longitudinal Survey of Youth Cohort.

PubMed

Kerr, William C; Lui, Camillia K; Williams, Edwina; Ye, Yu; Greenfield, Thomas K; Lown, E Anne

2017-02-01

The choice and definition of a comparison group in alcohol-related health studies remains a prominent issue in alcohol epidemiology due to potential biases in the risk estimates. The most commonly used comparison group has been current abstainers; however, this includes former drinkers who may have quit drinking due to health problems. Lifetime abstention could be the best option, but measurement issues, selection biases due to health and other risk factors, and small numbers in populations are important concerns. This study examines characteristics of lifetime abstention and occasional drinking that are relevant for alcohol-related health studies. This study used data from the National Longitudinal Survey of Youth 1979 cohort of 14 to 21 year olds followed through 2012 (n = 7,515). Definitions of abstinence and occasional drinking were constructed based on multiple measurements. Descriptive analyses were used to compare the definitions, and in further analysis, lifetime abstainers (n = 718) and lifetime minimal drinkers (n = 1,027) were compared with drinkers across demographics and early-life characteristics (i.e., religion, poverty, parental education, and family alcohol problems) in logistic regression models. Using a strict measurement of zero drinks from adolescence to the 50s, only 1.7% of the sample was defined as lifetime abstainer compared to a broader definition allowing a total of 1 drink over the lifetime that included 9.5% and to lifetime minimal drinking (a total of 3 drinks or less a month), which accounted for 13.7%. Factors significantly associated with lifetime abstention and lifetime minimal drinking included religion, poverty, having no family alcohol problems, Hispanic ethnicity, foreign-born, and female gender. Importantly, work-related health limitations in early life were significantly associated, but not childhood physical and mental health problems. Alcohol-related health studies should utilize lifetime classifications of drinkers

Population-based prevention of eating disorders: an application of the Rose prevention model.

PubMed

Austin, S B

2001-03-01

Several decades of concerted research on eating disorders have generated a broad range of proposed causal influences, but much of this etiologic research does not elucidate practical avenues for preventive interventions. Translating etiologic theory into community health interventions depends on the identification of key leverage points, factors that are amenable to public health intervention and provide an opportunity to maximize impact on the outcome of interest. Population-based preventive strategies, elaborated by epidemiologist Geoffrey Rose, can maximize the impact of public health interventions. In the case of eating disorders, Rose's model is instructive: Dieting stands out as risk behavior that may both fit Rose's model well and be a key leverage point for preventive intervention. Grounded in Rose's work, this article lodges a theoretical argument for the population-based prevention of eating disorders. In the introductory section, existing research on the epidemiology of dieting is reviewed, showing that it is extremely common among adolescent girls and women and that the behavior has been implicated as a causal factor for disordered eating. Next, new evidence is offered to build a case for how a population-wide reduction in dieting may be an effective strategy for prevention of eating pathology. Finally Rose's prevention framework is used to introduce a unique and provocative perspective on the prevention of eating disorders. Dieting is a normative behavior in our culture with psychological and physiological effects in the causal chain leading to eating pathology. This behavior may represent an ideal target for population-based prevention. Theoretical and empirical evidence suggests that a population-wide reduction in dieting may be a justifiable and effective strategy for prevention of eating pathology. Copyright 2001 American Health Foundation and Academic Press.

Habitable zone lifetimes of exoplanets around main sequence stars.

PubMed

Rushby, Andrew J; Claire, Mark W; Osborn, Hugh; Watson, Andrew J

2013-09-01

The potential habitability of newly discovered exoplanets is initially assessed by determining whether their orbits fall within the circumstellar habitable zone of their star. However, the habitable zone (HZ) is not static in time or space, and its boundaries migrate outward at a rate proportional to the increase in luminosity of a star undergoing stellar evolution, possibly including or excluding planets over the course of the star's main sequence lifetime. We describe the time that a planet spends within the HZ as its "habitable zone lifetime." The HZ lifetime of a planet has strong astrobiological implications and is especially important when considering the evolution of complex life, which is likely to require a longer residence time within the HZ. Here, we present results from a simple model built to investigate the evolution of the "classic" HZ over time, while also providing estimates for the evolution of stellar luminosity over time in order to develop a "hybrid" HZ model. These models return estimates for the HZ lifetimes of Earth and 7 confirmed HZ exoplanets and 27 unconfirmed Kepler candidates. The HZ lifetime for Earth ranges between 6.29 and 7.79×10⁹ years (Gyr). The 7 exoplanets fall in a range between ∼1 and 54.72 Gyr, while the 27 Kepler candidate planets' HZ lifetimes range between 0.43 and 18.8 Gyr. Our results show that exoplanet HD 85512b is no longer within the HZ, assuming it has an Earth analog atmosphere. The HZ lifetime should be considered in future models of planetary habitability as setting an upper limit on the lifetime of any potential exoplanetary biosphere, and also for identifying planets of high astrobiological potential for continued observational or modeling campaigns.

Digital Analysis and Sorting of Fluorescence Lifetime by Flow Cytometry

PubMed Central

Houston, Jessica P.; Naivar, Mark A.; Freyer, James P.

2010-01-01

Frequency-domain flow cytometry techniques are combined with modifications to the digital signal processing capabilities of the Open Reconfigurable Cytometric Acquisition System (ORCAS) to analyze fluorescence decay lifetimes and control sorting. Real-time fluorescence lifetime analysis is accomplished by rapidly digitizing correlated, radiofrequency modulated detector signals, implementing Fourier analysis programming with ORCAS’ digital signal processor (DSP) and converting the processed data into standard cytometric list mode data. To systematically test the capabilities of the ORCAS 50 MS/sec analog-to-digital converter (ADC) and our DSP programming, an error analysis was performed using simulated light scatter and fluorescence waveforms (0.5–25 ns simulated lifetime), pulse widths ranging from 2 to 15 µs, and modulation frequencies from 2.5 to 16.667 MHz. The standard deviations of digitally acquired lifetime values ranged from 0.112 to >2 ns, corresponding to errors in actual phase shifts from 0.0142° to 1.6°. The lowest coefficients of variation (<1%) were found for 10-MHz modulated waveforms having pulse widths of 6 µs and simulated lifetimes of 4 ns. Direct comparison of the digital analysis system to a previous analog phase-sensitive flow cytometer demonstrated similar precision and accuracy on measurements of a range of fluorescent microspheres, unstained cells and cells stained with three common fluorophores. Sorting based on fluorescence lifetime was accomplished by adding analog outputs to ORCAS and interfacing with a commercial cell sorter with a radiofrequency modulated solid-state laser. Two populations of fluorescent microspheres with overlapping fluorescence intensities but different lifetimes (2 and 7 ns) were separated to ~98% purity. Overall, the digital signal acquisition and processing methods we introduce present a simple yet robust approach to phase-sensitive measurements in flow cytometry. The ability to simply and inexpensively

Long-term fiscal implications of subsidizing in-vitro fertilization in Sweden: a lifetime tax perspective.

PubMed

Svensson, Anders; Connolly, Mark; Gallo, Federico; Hägglund, Leif

2008-11-01

In Sweden approximately 3% of annual births are conceived using assisted reproductive technologies (ART). In light of increasing use of ART in Sweden we estimate the lifetime future tax revenues of a child conceived by in-vitro fertilization (IVF) to establish whether public subsidy of IVF represents sound fiscal policy. A modified generational accounting model was developed to calculate the net present value (NPV) of average investment costs required to achieve an IVF-conceived child. The model simulates direct lifetime financial interactions between the child and the Swedish government. Within the model we assume average direct financial transfers are made to the individual (eg, child allowance, education, health care, pension, etc). In return, the individual transfers resources to the government through taxation based on anticipated average earnings. The difference between direct transfers and gross taxes paid equals the net-tax contribution. Individual tax contributions were held constant in the model. Based on average life-expectancy an individual born in 2005 will pay an undiscounted 32.5 million SEK in taxes to the Swedish government and receive 20.9 million SEK in direct financial transfers over their lifetime. When these figures are discounted and IVF costs are included in the analysis we obtain a lifetime NPV of 254,000 SEK with a break-even point at age 41 (the age of achieving a positive NPV) for an individual conceived through IVF. Based on results presented here we conclude that State-funded IVF in Sweden does not negatively impact the long run fiscal budget. Conversely, over an average lifetime an IVF offspring returns a positive net value to the State.

Positron lifetime studies of defect structures in Ba(1-x)K(x)BiO3

NASA Astrophysics Data System (ADS)

Obrien, J. C.; Howell, R. H.; Radousky, H. B.; Sterne, P. A.; Hinks, D. G.; Folkerts, T. J.; Shelton, R. N.

1990-12-01

Temperature-dependent positron lifetime experiments have been performed from room temperature to cryogenic temperatures on Ba(1-x)K(x)BiO3, for x = 0.4 and 0.5. From the temperature dependence of the positron lifetime in the normal state, we observe a clear signature of competition between separate defect populations to trap the positron. Theoretical calculations of lifetimes of free or trapped positrons have been performed on Ba(1-x)K(x)BiO3, to help identify these defects. Lifetime measurements separated by long times have been performed and evidence of aging effects in the sample defect populations is seen in these materials.

Preindustrial to Present-Day Changes in Tropospheric Hydroxyl Radical and Methane Lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP)

NASA Technical Reports Server (NTRS)

Naik, V.; Voulgarakis, A.; Fiore, A. M.; Horowitz, L. W.; Lamarque, J.-F.; Lin, M.; Prather, M. J.; Young, P. J.; Bergmann, D.; Cameron-Smith, P. J.;

Assessing three fish species ecological status in Colorado River, Grand Canyon based on physical habitat and population models.

PubMed

Yao, Weiwei; Chen, Yuansheng

2018-04-01

Colorado River is a unique ecosystem and provides important ecological services such as habitat for fish species as well as water power energy supplies. River management for this ecosystem requires assessment and decision support tools for fish which involves protecting, restoring as well as forecasting of future conditions. In this paper, a habitat and population model was developed and used to determine the levels of fish habitat suitability and population density in Colorado River between Lees Ferry and Lake Mead. The short term target fish populations are also predicted based on native fish recovery strategy. This model has been developed by combining hydrodynamics, heat transfer and sediment transport models with a habitat suitability index model and then coupling with habitat model into life stage population model. The fish were divided into four life stages according to the fish length. Three most abundant and typical native and non-native fish were selected as target species, which are rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and flannelmouth sucker (Catostomus latipinnis). Flow velocity, water depth, water temperature and substrates were used as the suitability indicators in habitat model and overall suitability index (OSI) as well as weight usable area (WUA) was used as an indicator in population model. A comparison was made between simulated fish population alteration and surveyed fish number fluctuation during 2000 to 2009. The application of this habitat and population model indicates that this model can be accurate present habitat situation and targets fish population dynamics of in the study areas. The analysis also indicates the flannelmouth sucker population will steadily increase while the rainbow trout will decrease based on the native fish recovery scheme. Copyright © 2018. Published by Elsevier Inc.

A Lifetime Prevalence of Comorbidity Between Bipolar Affective Disorder and Anxiety Disorders: A Meta-analysis of 52 Interview-based Studies of Psychiatric Population

PubMed Central

Nabavi, Behrouz; Mitchell, Alex J.; Nutt, David

2015-01-01

Background Bipolar affective disorder has a high rate of comorbidity with a multitude of psychiatric disorders and medical conditions. Among all the potential comorbidities, co-existing anxiety disorders stand out due to their high prevalence. Aims To determine the lifetime prevalence of comorbid anxiety disorders in bipolar affective disorder under the care of psychiatric services through systematic review and meta-analysis. Method Random effects meta-analyses were used to calculate the lifetime prevalence of comorbid generalised anxiety disorder, panic disorder, social anxiety disorder, specific phobia, agoraphobia, obsessive compulsive disorder and posttraumatic stress disorder in bipolar affective disorder. Results 52 studies were included in the meta-analysis. The rate of lifetime comorbidity was as follows: panic disorder 16.8% (95% CI 13.7–20.1), generalised anxiety disorder 14.4% (95% CI 10.8–18.3), social anxiety disorder13.3% (95% CI 10.1–16.9), post-traumatic stress disorder 10.8% (95% CI 7.3–14.9), specific phobia 10.8% (95% CI 8.2–13.7), obsessive compulsive disorder 10.7% (95% CI 8.7–13.0) and agoraphobia 7.8% (95% CI 5.2–11.0). The lifetime prevalence of any anxiety disorders in bipolar disorder was 42.7%. Conclusions Our results suggest a high rate of lifetime concurrent anxiety disorders in bipolar disorder. The diagnostic issues at the interface are particularly difficult because of the substantial symptom overlap. The treatment of co-existing conditions has clinically remained challenging. PMID:26629535

Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

PubMed Central

Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

2015-01-01

Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize. PMID:26437425

Genetic improvement of sow lifetime productivity

USDA-ARS?s Scientific Manuscript database

Sow lifetime productivity is a complex, yet important trait, that would benefit commercial populations if improved. It has been estimated that a sow must produce 3 litters to cover the cost of replacement; yet, nearly half of the gilts retained for breeding are removed prior to producing 3 litters r...

Cost-effectiveness of dronedarone and standard of care compared with standard of care alone: US results of an ATHENA lifetime model.

PubMed

Reynolds, Matthew R; Nilsson, Jonas; Akerborg, Orjan; Jhaveri, Mehul; Lindgren, Peter

2013-01-01

The first antiarrhythmic drug to demonstrate a reduced rate of cardiovascular hospitalization in atrial fibrillation/flutter (AF/AFL) patients was dronedarone in a placebo-controlled, double-blind, parallel arm Trial to assess the efficacy of dronedarone 400 mg bid for the prevention of cardiovascular Hospitalization or death from any cause in patiENts with Atrial fibrillation/atrial flutter (ATHENA trial). The potential cost-effectiveness of dronedarone in this patient population has not been reported in a US context. This study assesses the cost-effectiveness of dronedarone from a US health care payers' perspective. ATHENA patient data were applied to a patient-level health state transition model. Probabilities of health state transitions were derived from ATHENA and published data. Associated costs used in the model (2010 values) were obtained from published sources when trial data were not available. The base-case model assumed that patients were treated with dronedarone for the duration of ATHENA (mean 21 months) and were followed over a lifetime. Cost-effectiveness, from the payers' perspective, was determined using a Monte Carlo microsimulation (1 million fictitious patients). Dronedarone plus standard care provided 0.13 life years gained (LYG), and 0.11 quality-adjusted life years (QALYs), over standard care alone; cost/QALY was $19,520 and cost/LYG was $16,930. Compared to lower risk patients, patients at higher risk of stroke (Congestive heart failure, history of Hypertension, Age ≥ 75 years, Diabetes mellitus, and past history of Stroke or transient ischemic attack (CHADS(2)) scores 3-6 versus 0) had a lower cost/QALY ($9580-$16,000 versus $26,450). Cost/QALY was highest in scenarios assuming lifetime dronedarone therapy, no cardiovascular mortality benefit, no cost associated with AF/AFL recurrence on standard care, and when discounting of 5% was compared with 0%. By extrapolating the results of a large, multicenter, randomized clinical trial (ATHENA

Comparison of Accelerated Testing with Modeling to Predict Lifetime of CPV Solder Layers (Presentation)

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

Silverman, T. J.; Bosco, N.; Kurtz, S.

2012-03-01

Concentrating photovoltaic (CPV) cell assemblies can fail due to thermomechanical fatigue in the die-attach layer. In this presentation, we show the latest results from our computational model of thermomechanical fatigue. The model is used to estimate the relative lifetime of cell assemblies exposed to various temperature histories consistent with service and with accelerated testing. We also present early results from thermal cycling experiments designed to help validate the computational model.

Lifetime physical activity and female stress urinary incontinence.

PubMed

Nygaard, Ingrid E; Shaw, Janet M; Bardsley, Tyler; Egger, Marlene J

2015-07-01

We sought to estimate whether moderate/severe stress urinary incontinence (SUI) in middle-aged women is associated with overall lifetime physical activity (including leisure, household, outdoor, and occupational), as well as lifetime leisure (recreational), lifetime strenuous, and strenuous activity during the teen years. Recruitment for this case-control study was conducted in primary-care-level family medicine and gynecology clinics. A total of 1538 enrolled women ages 39-65 years underwent a Pelvic Organ Prolapse Quantification examination to assess vaginal support. Based on Incontinence Severity Index scores, cases had moderate/severe and controls had no/mild SUI. We excluded 349 with vaginal descent at/below the hymen (pelvic organ prolapse), 194 who did not return questionnaires, and 110 with insufficient activity data for analysis. In all, 213 cases were frequency matched 1:1 by age group to controls. Physical activity was measured using the Lifetime Physical Activity Questionnaire, in which women recall activity from menarche to present. We created separate multivariable logistic regression models for activity measures. SUI odds increased slightly with overall lifetime activity (odds ratio [OR], 1.20 per 70 additional metabolic equivalent of task-h/wk; 95% confidence interval [CI], 1.02-1.41), and were not associated with lifetime strenuous activity (OR, 1.11; 95% CI, 0.99-1.25). In quintile analysis of lifetime leisure activity, which demonstrated a nonlinear pattern, all quintiles incurred about half the odds of SUI compared to reference (second quintile; P = .009). Greater strenuous activity in teen years modestly increased SUI odds (OR, 1.37 per 7 additional h/wk; 95% CI, 1.09-1.71); OR, 1.75; 95% CI, 1.15-2.66 in sensitivity analysis adjusting for measurement error. The predicted probability of SUI rose linearly in women exceeding 7.5 hours of strenuous activity/wk during teen years. Teen strenuous activity had a similar effect on SUI odds when

Progress toward a new measurement of the neutron lifetime

NASA Astrophysics Data System (ADS)

Grammer, Kyle

2015-04-01

Free neutron decay is the simplest nuclear beta decay. A precise value for the neutron lifetime is valuable for standard model consistency tests and Big Bang Nucleosynthesis models. There is a disagreement between the measured neutron lifetime from cold neutron beam experiments and ultracold neutron storage experiments. A new measurement of the neutron lifetime using the beam method is planned at the National Institute of Standards and Technology Center for Neutron Research. Experimental improvements should result in a 1s uncertainty measurement of the neutron lifetime. The technical improvements and the path towards the new measurement will be discussed. This work is supported by DOE Office of Science, NIST, and NSF.

Fluorescence intensity- and lifetime-based glucose sensing using glucose/galactose-binding protein.

PubMed

Pickup, John C; Khan, Faaizah; Zhi, Zheng-Liang; Coulter, Jonathan; Birch, David J S

2013-01-01

We review progress in our laboratories toward developing in vivo glucose sensors for diabetes that are based on fluorescence labeling of glucose/galactose-binding protein. Measurement strategies have included both monitoring glucose-induced changes in fluorescence resonance energy transfer and labeling with the environmentally sensitive fluorophore, badan. Measuring fluorescence lifetime rather than intensity has particular potential advantages for in vivo sensing. A prototype fiber-optic-based glucose sensor using this technology is being tested. © 2013 Diabetes Technology Society.

A model-based economic evaluation of improved primary care management of patients with type 2 diabetes in Australia.

PubMed

Haji Ali Afzali, Hossein; Gray, Jodi; Beilby, Justin; Holton, Christine; Karnon, Jonathan

2013-12-01

There are few studies investigating the economic value of the Australian practice nurse workforce on the management of chronic conditions. This is particularly important in Australia, where the government needs evidence to inform decisions on whether to maintain or redirect current financial incentives that encourage practices to recruit practice nurses. The objective of this study was to estimate the lifetime costs and quality-adjusted life-years (QALYs) associated with two models of practice nurse involvement in clinical-based activities (high and low level) in the management of type 2 diabetes within the primary care setting. A previously validated state transition model (the United Kingdom Prospective Diabetes Study Outcomes Model) was adapted, which uses baseline prognostic factors (e.g. gender, haemoglobin A1c [HbA1c]) to predict the risk of occurrence of diabetes-related complications (e.g. stroke). The model was populated by data from Australian and UK observational studies. Costs and utility values associated with complications were summed over patients' lifetimes to estimate costs and QALY gains from the perspective of the health care system. All costs were expressed in 2011 Australian dollars (AU$). The base-case analysis assumed a 40-year time horizon with an annual discount rate of 5 %. Relative to low-level involvement of practice nurses in the provision of clinical-based activities, the high-level model was associated with lower mean lifetime costs of management of complications (-AU$8,738; 95 % confidence interval [CI] -AU$12,522 to -AU$4,954), and a greater average gain in QALYs (0.3; 95 % CI 0.2-0.4). A range of sensitivity analyses were performed, in which the high-level model was dominant in all cases. Our results suggest that the high-level model is a dominant management strategy over the low-level model in all modelled scenarios. These findings indicate the need for effective primary care-based incentives to encourage general practices not

A Q-Learning-Based Delay-Aware Routing Algorithm to Extend the Lifetime of Underwater Sensor Networks.

PubMed

Jin, Zhigang; Ma, Yingying; Su, Yishan; Li, Shuo; Fu, Xiaomei

2017-07-19

Underwater sensor networks (UWSNs) have become a hot research topic because of their various aquatic applications. As the underwater sensor nodes are powered by built-in batteries which are difficult to replace, extending the network lifetime is a most urgent need. Due to the low and variable transmission speed of sound, the design of reliable routing algorithms for UWSNs is challenging. In this paper, we propose a Q-learning based delay-aware routing (QDAR) algorithm to extend the lifetime of underwater sensor networks. In QDAR, a data collection phase is designed to adapt to the dynamic environment. With the application of the Q-learning technique, QDAR can determine a global optimal next hop rather than a greedy one. We define an action-utility function in which residual energy and propagation delay are both considered for adequate routing decisions. Thus, the QDAR algorithm can extend the network lifetime by uniformly distributing the residual energy and provide lower end-to-end delay. The simulation results show that our protocol can yield nearly the same network lifetime, and can reduce the end-to-end delay by 20-25% compared with a classic lifetime-extended routing protocol (QELAR).

A Q-Learning-Based Delay-Aware Routing Algorithm to Extend the Lifetime of Underwater Sensor Networks

PubMed Central

Ma, Yingying; Su, Yishan; Li, Shuo; Fu, Xiaomei

2017-01-01

Underwater sensor networks (UWSNs) have become a hot research topic because of their various aquatic applications. As the underwater sensor nodes are powered by built-in batteries which are difficult to replace, extending the network lifetime is a most urgent need. Due to the low and variable transmission speed of sound, the design of reliable routing algorithms for UWSNs is challenging. In this paper, we propose a Q-learning based delay-aware routing (QDAR) algorithm to extend the lifetime of underwater sensor networks. In QDAR, a data collection phase is designed to adapt to the dynamic environment. With the application of the Q-learning technique, QDAR can determine a global optimal next hop rather than a greedy one. We define an action-utility function in which residual energy and propagation delay are both considered for adequate routing decisions. Thus, the QDAR algorithm can extend the network lifetime by uniformly distributing the residual energy and provide lower end-to-end delay. The simulation results show that our protocol can yield nearly the same network lifetime, and can reduce the end-to-end delay by 20–25% compared with a classic lifetime-extended routing protocol (QELAR). PMID:28753951

Development of a lifetime merit-based selection index for US dairy grazing systems

USDA-ARS?s Scientific Manuscript database

Pasture-based dairy producers in the US face costs, revenues and management challenges that differ from those associated with conventional dairy production systems. Three Grazing Merit indexes (GM$1, GM$2, and GM$3), parallel to the US Lifetime Net Merit (NM$) index, were constructed using economic ...

The atmospheric lifetime of black carbon

NASA Astrophysics Data System (ADS)

Cape, J. N.; Coyle, M.; Dumitrean, P.

2012-11-01

Black carbon (BC) in the atmosphere contributes to the human health effects of particulate matter and contributes to radiative forcing of climate. The lifetime of BC, particularly the smaller particle sizes (PM2.5) which can be transported over long distances, is therefore an important factor in determining the range of such effects, and the spatial footprint of emission controls. Theory and models suggest that the typical lifetime of BC is around one week. The frequency distributions of measurements of a range of hydrocarbons at a remote rural site in southern Scotland (Auchencorth Moss) between 2007 and 2010 have been used to quantify the relationship between atmospheric lifetime and the geometric standard deviation of observed concentration. The analysis relies on an assumed common major emission source for hydrocarbons and BC, namely diesel-engined vehicles. The logarithm of the standard deviation of the log-transformed concentration data is linearly related to hydrocarbon lifetime, and the same statistic for BC can be used to assess the lifetime of BC relative to the hydrocarbons. Annual average data show BC lifetimes in the range 4-12 days, for an assumed OH concentration of 7 × 105 cm-3. At this site there is little difference in BC lifetime between winter and summer, despite a 3-fold difference in relative hydrocarbon lifetimes. This observation confirms the role of wet deposition as an important removal process for BC, as there is no difference in precipitation between winter and summer at this site. BC lifetime was significantly greater in 2010, which had 23% less rainfall than the preceding 3 years.

Fluorescence lifetime measurements in flow cytometry

NASA Astrophysics Data System (ADS)

Beisker, Wolfgang; Klocke, Axel

1997-05-01

Fluorescence lifetime measurements provide insights int eh dynamic and structural properties of dyes and their micro- environment. The implementation of fluorescence lifetime measurements in flow cytometric systems allows to monitor large cell and particle populations with high statistical significance. In our system, a modulated laser beam is used for excitation and the phase shift of the fluorescence signal recorded with a fast computer controlled digital oscilloscope is processed digitally to determine the phase shift with respect to a reference beam by fast fourier transform. Total fluorescence intensity as well as other parameters can be determined simultaneously from the same fluorescence signal. We use the epi-illumination design to allow the use of high numerical apertures to collect as much light as possible to ensure detection of even weak fluorescence. Data storage and processing is done comparable to slit-scan flow cytometric data using data analysis system. The results are stored, displayed, combined with other parameters and analyzed as normal listmode data. In our report we discuss carefully the signal to noise ratio for analog and digital processed lifetime signals to evaluate the theoretical minimum fluorescence intensity for lifetime measurements. Applications to be presented include DNA staining, parameters of cell functions as well as different applications in non-mammalian cells such as algae.

Survival models for harvest management of mourning dove populations

USGS Publications Warehouse

Otis, D.L.

2002-01-01

Quantitative models of the relationship between annual survival and harvest rate of migratory game-bird populations are essential to science-based harvest management strategies. I used the best available band-recovery and harvest data for mourning doves (Zenaida macroura) to build a set of models based on different assumptions about compensatory harvest mortality. Although these models suffer from lack of contemporary data, they can be used in development of an initial set of population models that synthesize existing demographic data on a management-unit scale, and serve as a tool for prioritization of population demographic information needs. Credible harvest management plans for mourning dove populations will require a long-term commitment to population monitoring and iterative population analysis.

Study on efficiency droop in InGaN/GaN light-emitting diodes based on differential carrier lifetime analysis

NASA Astrophysics Data System (ADS)

Meng, Xiao; Wang, Lai; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yanjun; Xiong, Bing; Wang, Jian; Li, Hongtao

2016-01-01

Efficiency droop is currently one of the most popular research problems for GaN-based light-emitting diodes (LEDs). In this work, a differential carrier lifetime measurement system is optimized to accurately determine carrier lifetimes (τ) of blue and green LEDs under different injection current (I). By fitting the τ-I curves and the efficiency droop curves of the LEDs according to the ABC carrier rate equation model, the impact of Auger recombination and carrier leakage on efficiency droop can be characterized simultaneously. For the samples used in this work, it is found that the experimental τ-I curves cannot be described by Auger recombination alone. Instead, satisfactory fitting results are obtained by taking both carrier leakage and carriers delocalization into account, which implies carrier leakage plays a more significant role in efficiency droop at high injection level.

Model-based estimators of density and connectivity to inform conservation of spatially structured populations

USGS Publications Warehouse

Morin, Dana J.; Fuller, Angela K.; Royle, J. Andrew; Sutherland, Chris

2017-01-01

Conservation and management of spatially structured populations is challenging because solutions must consider where individuals are located, but also differential individual space use as a result of landscape heterogeneity. A recent extension of spatial capture–recapture (SCR) models, the ecological distance model, uses spatial encounter histories of individuals (e.g., a record of where individuals are detected across space, often sequenced over multiple sampling occasions), to estimate the relationship between space use and characteristics of a landscape, allowing simultaneous estimation of both local densities of individuals across space and connectivity at the scale of individual movement. We developed two model-based estimators derived from the SCR ecological distance model to quantify connectivity over a continuous surface: (1) potential connectivity—a metric of the connectivity of areas based on resistance to individual movement; and (2) density-weighted connectivity (DWC)—potential connectivity weighted by estimated density. Estimates of potential connectivity and DWC can provide spatial representations of areas that are most important for the conservation of threatened species, or management of abundant populations (i.e., areas with high density and landscape connectivity), and thus generate predictions that have great potential to inform conservation and management actions. We used a simulation study with a stationary trap design across a range of landscape resistance scenarios to evaluate how well our model estimates resistance, potential connectivity, and DWC. Correlation between true and estimated potential connectivity was high, and there was positive correlation and high spatial accuracy between estimated DWC and true DWC. We applied our approach to data collected from a population of black bears in New York, and found that forested areas represented low levels of resistance for black bears. We demonstrate that formal inference about measures

Analysis of Present Day and Future OH and Methane Lifetime in the ACCMIP Simulations

NASA Technical Reports Server (NTRS)

Voulgarakis, A.; Naik, V.; Lamarque, J. -F.; Shindell, D. T.; Young, P. J.; Prather, M. J.; Wild, O.; Field, R. D.; Bergmann, D.; Cameron-Smith P.;

Single-shot lifetime-based PSP and TSP measurements on turbocharger compressor blades

NASA Astrophysics Data System (ADS)

Peng, Di; Jiao, Lingrui; Yu, Yuelong; Liu, Yingzheng; Oshio, Tetsuya; Kawakubo, Tomoki; Yakushiji, Akimitsu

2017-09-01

Fast-responding pressure-sensitive paint (Fast PSP) and temperature-sensitive paint (TSP) measurements were conducted on two turbocharger compressors using a single-shot lifetime-based technique. The fast PSP and TSP were applied on separate blades of one compressor, and both paints were excited by a pulsed 532 nm Nd:YAG laser. The luminescent decay signals following the laser pulse were recorded by a CCD camera in a double-exposure mode. Instantaneous pressure and temperature fields on compressor blades were obtained simultaneously, for rotation speeds up to 150,000 rpm. The variations in pressure and temperature fields with rotation speed, flow rate and runtime were clearly visualized, showing the advantage of high spatial resolution. Severe image blurring problems and significant temperature-induced errors in the PSP results were found at high rotation speeds. The first issue was addressed by incorporating a deconvolution-based deblurring algorithm to recover the clear image from the blurred image using the combination of luminescent lifetime and rotation speed. The second issue was resolved by applying a pixel-by-pixel temperature correction based on the TSP results. The current technique has shown great capabilities in flow diagnostics of turbomachinery and can serve as a powerful tool for CFD validations and design optimizations.

Lifetime Alcohol Use & Cognitive Performance in Older Adults

PubMed Central

Kalapatapu, Raj K.; Ventura, Maria I.; Barnes, Deborah E.

2016-01-01

Background Substance use is an important clinical issue in the older adult population. As older adults are susceptible to cognitive disorders, the intersection of the fields of substance use and cognitive neuroscience is an active area of research. Prior studies of alcohol use and cognitive performance are mixed, and inconsistencies may be due to under- or over-adjustment for confounders. Aim This manuscript adds to this literature by conducting a secondary analysis of self-reported lifetime history of alcohol use and cognitive performance in older adults (n = 133). We hypothesized that current alcohol users would have poorer cognitive performance compared to never/minimal and former alcohol users. Methods Older adult participants were classified into never/minimal alcohol users, former alcohol users, and current alcohol users. A neurocognitive battery included a global cognitive measure and individual measures of attention, memory, fluency, and executive function. A directed acyclic graph (DAG)-based approach was used to select variables to be included in the multiple linear regression models. Results Though unadjusted analyses showed some significant associations between alcohol use and cognitive performance, all associations between alcohol use and cognitive performance were eliminated after adjusting for age, education, sex, race and smoking pack years. Alcohol drink years were not significantly associated with cognitive performance among current and former alcohol users. Discussion These results suggest that lifetime alcohol use is not significantly associated with cognitive performance in older adults after adjustment for key confounders. Inconsistencies in prior studies may be due to uncontrolled confounding and/or unnecessary adjustment of mediators and/or colliders. PMID:27719514

Prolonging fuel cell stack lifetime based on Pontryagin's Minimum Principle in fuel cell hybrid vehicles and its economic influence evaluation

NASA Astrophysics Data System (ADS)

Zheng, C. H.; Xu, G. Q.; Park, Y. I.; Lim, W. S.; Cha, S. W.

2014-02-01

The lifetime of fuel cell stacks is a major issue currently, especially for automotive applications. In order to take into account the lifetime of fuel cell stacks while considering the fuel consumption minimization in fuel cell hybrid vehicles (FCHVs), a Pontryagin's Minimum Principle (PMP)-based power management strategy is proposed in this research. This strategy has the effect of prolonging the lifetime of fuel cell stacks. However, there is a tradeoff between the fuel cell stack lifetime and the fuel consumption when this strategy is applied to an FCHV. Verifying the positive economic influence of this strategy is necessary in order to demonstrate its superiority. In this research, the economic influence of the proposed strategy is assessed according to an evaluating cost which is dependent on the fuel cell stack cost, the hydrogen cost, the fuel cell stack lifetime, and the lifetime prolonging impact on the fuel cell stack. Simulation results derived from the proposed power management strategy are also used to evaluate the economic influence. As a result, the positive economic influence of the proposed PMP-based power management strategy is proved for both current and future FCHVs.

Kinetic Model of Growth of Arthropoda Populations

NASA Astrophysics Data System (ADS)

Ershov, Yu. A.; Kuznetsov, M. A.

2018-05-01

Kinetic equations were derived for calculating the growth of crustacean populations ( Crustacea) based on the biological growth model suggested earlier using shrimp ( Caridea) populations as an example. The development cycle of successive stages for populations can be represented in the form of quasi-chemical equations. The kinetic equations that describe the development cycle of crustaceans allow quantitative prediction of the development of populations depending on conditions. In contrast to extrapolation-simulation models, in the developed kinetic model of biological growth the kinetic parameters are the experimental characteristics of population growth. Verification and parametric identification of the developed model on the basis of the experimental data showed agreement with experiment within the error of the measurement technique.

Progress toward a new measurement of the neutron lifetime

NASA Astrophysics Data System (ADS)

Grammer, Kyle

2015-10-01

Free neutron decay is the simplest nuclear beta decay. A precise value for the neutron lifetime is valuable for standard model consistency tests and Big Bang Nucleosynthesis models. There is a disagreement between the measured neutron lifetime from cold neutron beam experiments and ultracold neutron storage experiments. A new measurement of the neutron lifetime using the beam method is planned at the National Institute of Standards and Technology Center for Neutron Research. Experimental improvements should result in a 1s uncertainty measurement of the neutron lifetime. The technical improvements, recent apparatus tests, and the path towards the new measurement will be discussed. This work is supported by DOE Office of Science, NIST, and NSF.

Factors associated with illicit drugs' lifetime and frequent/heavy use among students results from a population survey.

PubMed

Bitancourt, Tânia; Tissot, Maria Cristina Ribeiro Grilli; Fidalgo, Thiago Marques; Galduróz, José Carlos Fernandes; da Silveira Filho, Dartiu Xavier

2016-03-30

Substance use among teenage students and factors associated were investigated through a survey using a questionnaire adapted from the WHO's Program on Research and Reporting on the Epidemiology of Drug Dependence, additional questions on family factors and personal risks, and the Coopersmith Self-Esteem Inventory, adapted to Brazil. The target population consisted of 3891 10-22-year-old students from the city of Embu das Artes, São Paulo, Brazil. The prevalence of lifetime substance use was 26.7%. Most commonly used substances were energy drinks combined with alcohol (19%), solvents (11.2%) and marijuana (4.8%). Almost 60% of the students had already tried alcohol and 18.2% had tried tobacco. Factors associated to lifetime substance use were: lower self-esteem, going to nightclubs at least twice a week, use of alcohol, trying tobacco, bad relationship with the mother, permissive mothers, practicing sports as an obligation, working, and higher socioeconomic level. Concerning frequent/heavy substance use, chances were found to be higher among students who had use tobacco and alcohol, going to nightclubs at least twice a week, and those with lower self-esteem. Preventive actions concerning drug use should focus on avoiding the first experimentation, approaching family relationships, and improving students' self-esteem. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Modeling Honey Bee Populations.

PubMed

Torres, David J; Ricoy, Ulises M; Roybal, Shanae

2015-01-01

Eusocial honey bee populations (Apis mellifera) employ an age stratification organization of egg, larvae, pupae, hive bees and foraging bees. Understanding the recent decline in honey bee colonies hinges on understanding the factors that impact each of these different age castes. We first perform an analysis of steady state bee populations given mortality rates within each bee caste and find that the honey bee colony is highly susceptible to hive and pupae mortality rates. Subsequently, we study transient bee population dynamics by building upon the modeling foundation established by Schmickl and Crailsheim and Khoury et al. Our transient model based on differential equations accounts for the effects of pheromones in slowing the maturation of hive bees to foraging bees, the increased mortality of larvae in the absence of sufficient hive bees, and the effects of food scarcity. We also conduct sensitivity studies and show the effects of parameter variations on the colony population.

Modeling Honey Bee Populations

PubMed Central

Torres, David J.; Ricoy, Ulises M.; Roybal, Shanae

2015-01-01

Eusocial honey bee populations (Apis mellifera) employ an age stratification organization of egg, larvae, pupae, hive bees and foraging bees. Understanding the recent decline in honey bee colonies hinges on understanding the factors that impact each of these different age castes. We first perform an analysis of steady state bee populations given mortality rates within each bee caste and find that the honey bee colony is highly susceptible to hive and pupae mortality rates. Subsequently, we study transient bee population dynamics by building upon the modeling foundation established by Schmickl and Crailsheim and Khoury et al. Our transient model based on differential equations accounts for the effects of pheromones in slowing the maturation of hive bees to foraging bees, the increased mortality of larvae in the absence of sufficient hive bees, and the effects of food scarcity. We also conduct sensitivity studies and show the effects of parameter variations on the colony population. PMID:26148010

Radiative lifetimes of zincblende CdSe/CdS quantum dots

DOE PAGES

Gong, Ke; Martin, James E.; Shea-Rohwer, Lauren E.; ...

2015-01-02

Recent synthetic advances have made available very monodisperse zincblende CdSe/CdS quantum dots having near-unity photoluminescence quantum yields. Because of the absence of nonradiative decay pathways, accurate values of the radiative lifetimes can be obtained from time-resolved PL measurements. Radiative lifetimes can also be obtained from the Einstein relations, using the static absorption spectra and the relative thermal populations in the angular momentum sublevels. We found that one of the inputs into these calculations is the shell thickness, and it is useful to be able to determine shell thickness from spectroscopic measurements. We use an empirically corrected effective mass model tomore » produce a “map” of exciton wavelength as a function of core size and shell thickness. These calculations use an elastic continuum model and the known lattice and elastic constants to include the effect of lattice strain on the band gap energy. The map is in agreement with the known CdSe sizing curve and with the shell thicknesses of zincblende core/shell particles obtained from TEM images. Furthermore, if selenium–sulfur diffusion is included and lattice strain is omitted from the calculation then the resulting map is appropriate for wurtzite CdSe/CdS quantum dots synthesized at high temperatures, and this map is very similar to one previously reported (J. Am. Chem. Soc. 2009, 131, 14299). Radiative lifetimes determined from time-resolved measurements are compared to values obtained from the Einstein relations, and found to be in excellent agreement. For a specific core size (2.64 nm diameter, in the present case), radiative lifetimes are found to decrease with increasing shell thickness. Thus, this is similar to the size dependence of one-component CdSe quantum dots and in contrast to the size dependence in type-II quantum dots.« less

Population-based contracting (population health): part II.

PubMed

Jacofsky, D J

2017-11-01

Modern healthcare contracting is shifting the responsibility for improving quality, enhancing community health and controlling the total cost of care for patient populations from payers to providers. Population-based contracting involves capitated risk taken across an entire population, such that any included services within the contract are paid for by the risk-bearing entity throughout the term of the agreement. Under such contracts, a risk-bearing entity, which may be a provider group, a hospital or another payer, administers the contract and assumes risk for contractually defined services. These contracts can be structured in various ways, from professional fee capitation to full global per member per month diagnosis-based risk. The entity contracting with the payer must have downstream network contracts to provide the care and facilities that it has agreed to provide. Population health is a very powerful model to reduce waste and costs. It requires a deep understanding of the nuances of such contracting and the appropriate infrastructure to manage both networks and risk. Cite this article: Bone Joint J 2017;99-B:1431-4. ©2017 The British Editorial Society of Bone & Joint Surgery.

A cognitive-consistency based model of population wide attitude change.

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

Lakkaraju, Kiran; Speed, Ann Elizabeth

Attitudes play a significant role in determining how individuals process information and behave. In this paper we have developed a new computational model of population wide attitude change that captures the social level: how individuals interact and communicate information, and the cognitive level: how attitudes and concept interact with each other. The model captures the cognitive aspect by representing each individuals as a parallel constraint satisfaction network. The dynamics of this model are explored through a simple attitude change experiment where we vary the social network and distribution of attitudes in a population.

Lifetime measurements using two-step laser excitation for high-lying even-parity levels and improved theoretical oscillator strengths in Y II

NASA Astrophysics Data System (ADS)

Palmeri, P.; Quinet, P.; Lundberg, H.; Engström, L.; Nilsson, H.; Hartman, H.

2017-10-01

We report new time-resolved laser-induced fluorescence lifetime measurements for 22 highly excited even-parity levels in singly ionized yttrium (Y II). To populate these levels belonging to the configurations 4d6s, 5s6s 4d5d, 5p2, 4d7s and 4d6d, a two-step laser excitation technique was used. Our previous pseudo-relativistic Hartree-Fock model (Biémont et al. 2011) was improved by extending the configuration interaction up to n = 10 to reproduce the new experimental lifetimes. A set of semi-empirical oscillator strengths extended to transitions falling in the spectral range λλ194-3995 nm, depopulating these 22 even-parity levels in Y II, is presented and compared to the values found in the Kurucz's data base (Kurucz 2011).

Evaluating effects of Everglades restoration on American crocodile populations in south Florida using a spatially-explicit, stage-based population model

USGS Publications Warehouse

Green, Timothy W.; Slone, Daniel H.; Swain, Eric D.; Cherkiss, Michael S.; Lohmann, Melinda; Mazzotti, Frank J.; Rice, Kenneth G.

2014-01-01

The distribution and abundance of the American crocodile (Crocodylus acutus) in the Florida Everglades is dependent on the timing, amount, and location of freshwater flow. One of the goals of the Comprehensive Everglades Restoration Plan (CERP) is to restore historic freshwater flows to American crocodile habitat throughout the Everglades. To predict the impacts on the crocodile population from planned restoration activities, we created a stage-based spatially explicit crocodile population model that incorporated regional hydrology models and American crocodile research and monitoring data. Growth and survival were influenced by salinity, water depth, and density-dependent interactions. A stage-structured spatial model was used with discrete spatial convolution to direct crocodiles toward attractive sources where conditions were favorable. The model predicted that CERP would have both positive and negative impacts on American crocodile growth, survival, and distribution. Overall, crocodile populations across south Florida were predicted to decrease approximately 3 % with the implementation of CERP compared to future conditions without restoration, but local increases up to 30 % occurred in the Joe Bay area near Taylor Slough, and local decreases up to 30 % occurred in the vicinity of Buttonwood Canal due to changes in salinity and freshwater flows.

Conformer lifetimes of ethyl cyanoformate from exchange-averaged rotational spectra.

PubMed

True, Nancy S

2009-06-25

Ethyl cyanoformate exists as a mixture of two conformers but displays three R-branch a-type band series in its rotational spectrum. Simulations with population fractions 0.37 at 210 K and 0.70 at 297 K undergoing conformer exchange with average conformer lifetimes, , shorter than approximately 40 ps at approximately 210 K and shorter than approximately 37 ps at 297 K reproduce the experimental spectra between 26.5 and 38 GHz, the exchanging species accounting for the third set of bands. The upper-limit 's are 1 order of magnitude longer than RRKM theory predictions and the population fractions are consistent with the total population with energy above 700 cm(-1), approximately twice the conformer interconversion barrier height. Model calculations indicate that extensive K-sublevel mixing in individual molecular eigenstates can produce the large population and the narrow distribution of the rotational-constant sum, B + C, consistent with the observed exchange-averaged band series.

Lifetime occupational exposure to metals and welding fumes, and risk of glioma: a 7-country population-based case-control study.

PubMed

Parent, Marie-Elise; Turner, Michelle C; Lavoué, Jérôme; Richard, Hugues; Figuerola, Jordi; Kincl, Laurel; Richardson, Lesley; Benke, Geza; Blettner, Maria; Fleming, Sarah; Hours, Martine; Krewski, Daniel; McLean, David; Sadetzki, Siegal; Schlaefer, Klaus; Schlehofer, Brigitte; Schüz, Joachim; Siemiatycki, Jack; van Tongeren, Martie; Cardis, Elisabeth

2017-08-25

Brain tumor etiology is poorly understood. Based on their ability to pass through the blood-brain barrier, it has been hypothesized that exposure to metals may increase the risk of brain cancer. Results from the few epidemiological studies on this issue are limited and inconsistent. We investigated the relationship between glioma risk and occupational exposure to five metals - lead, cadmium, nickel, chromium and iron- as well as to welding fumes, using data from the seven-country INTEROCC study. A total of 1800 incident glioma cases and 5160 controls aged 30-69 years were included in the analysis. Lifetime occupational exposure to the agents was assessed using the INTEROCC JEM, a modified version of the Finnish job exposure matrix FINJEM. In general, cases had a slightly higher prevalence of exposure to the various metals and welding fumes than did controls, with the prevalence among ever exposed ranging between 1.7 and 2.2% for cadmium to 10.2 and 13.6% for iron among controls and cases, respectively. However, in multivariable logistic regression analyses, there was no association between ever exposure to any of the agents and risk of glioma with odds ratios (95% confidence intervals) ranging from 0.8 (0.7-1.0) for lead to 1.1 (0.7-1.6) for cadmium. Results were consistent across models considering cumulative exposure or duration, as well as in all sensitivity analyses conducted. Findings from this large-scale international study provide no evidence for an association between occupational exposure to any of the metals under scrutiny or welding fumes, and risk of glioma.

Agile Model Driven Development of Electronic Health Record-Based Specialty Population Registries.

PubMed

Kannan, Vaishnavi; Fish, Jason C; Willett, DuWayne L

2016-02-01

The transformation of the American healthcare payment system from fee-for-service to value-based care increasingly makes it valuable to develop patient registries for specialized populations, to better assess healthcare quality and costs. Recent widespread adoption of Electronic Health Records (EHRs) in the U.S. now makes possible construction of EHR-based specialty registry data collection tools and reports, previously unfeasible using manual chart abstraction. But the complexities of specialty registry EHR tools and measures, along with the variety of stakeholders involved, can result in misunderstood requirements and frequent product change requests, as users first experience the tools in their actual clinical workflows. Such requirements churn could easily stall progress in specialty registry rollout. Modeling a system's requirements and solution design can be a powerful way to remove ambiguities, facilitate shared understanding, and help evolve a design to meet newly-discovered needs. "Agile Modeling" retains these values while avoiding excessive unused up-front modeling in favor of iterative incremental modeling. Using Agile Modeling principles and practices, in calendar year 2015 one institution developed 58 EHR-based specialty registries, with 111 new data collection tools, supporting 134 clinical process and outcome measures, and enrolling over 16,000 patients. The subset of UML and non-UML models found most consistently useful in designing, building, and iteratively evolving EHR-based specialty registries included User Stories, Domain Models, Use Case Diagrams, Decision Trees, Graphical User Interface Storyboards, Use Case text descriptions, and Solution Class Diagrams.

Stochastic population dynamic models as probability networks

Treesearch

M.E. and D.C. Lee Borsuk

2009-01-01

The dynamics of a population and its response to environmental change depend on the balance of birth, death and age-at-maturity, and there have been many attempts to mathematically model populations based on these characteristics. Historically, most of these models were deterministic, meaning that the results were strictly determined by the equations of the model and...

Estimating lifetime and age-conditional probabilities of developing cancer.

PubMed

Wun, L M; Merrill, R M; Feuer, E J

1998-01-01

Lifetime and age-conditional risk estimates of developing cancer provide a useful summary to the public of the current cancer risk and how this risk compares with earlier periods and among select subgroups of society. These reported estimates, commonly quoted in the popular press, have the potential to promote early detection efforts, to increase cancer awareness, and to serve as an aid in study planning. However, they can also be easily misunderstood and frightening to the general public. The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute and the American Cancer Society have recently begun including in annual reports lifetime and age-conditional risk estimates of developing cancer. These risk estimates are based on incidence rates that reflect new cases of the cancer in a population free of the cancer. To compute these estimates involves a cancer prevalence adjustment that is computed cross-sectionally from current incidence and mortality data derived within a multiple decrement life table. This paper presents a detailed description of the methodology for deriving lifetime and age-conditional risk estimates of developing cancer. In addition, an extension is made which, using a triple decrement life table, adjusts for a surgical procedure that removes individuals from the risk of developing a given cancer. Two important results which provide insights into the basic methodology are included in the discussion. First, the lifetime risk estimate does not depend on the cancer prevalence adjustment, although this is not the case for age-conditional risk estimates. Second, the lifetime risk estimate is always smaller when it is corrected for a surgical procedure that takes people out of the risk pool to develop the cancer. The methodology is applied to corpus and uterus NOS cancers, with a correction made for hysterectomy prevalence. The interpretation and limitations of risk estimates are also discussed.

Modelling impacts of performance on the probability of reproducing, and thereby on productive lifespan, allow prediction of lifetime efficiency in dairy cows.

PubMed

Phuong, H N; Blavy, P; Martin, O; Schmidely, P; Friggens, N C

2016-01-01

Reproductive success is a key component of lifetime efficiency - which is the ratio of energy in milk (MJ) to energy intake (MJ) over the lifespan, of cows. At the animal level, breeding and feeding management can substantially impact milk yield, body condition and energy balance of cows, which are known as major contributors to reproductive failure in dairy cattle. This study extended an existing lifetime performance model to incorporate the impacts that performance changes due to changing breeding and feeding strategies have on the probability of reproducing and thereby on the productive lifespan, and thus allow the prediction of a cow's lifetime efficiency. The model is dynamic and stochastic, with an individual cow being the unit modelled and one day being the unit of time. To evaluate the model, data from a French study including Holstein and Normande cows fed high-concentrate diets and data from a Scottish study including Holstein cows selected for high and average genetic merit for fat plus protein that were fed high- v. low-concentrate diets were used. Generally, the model consistently simulated productive and reproductive performance of various genotypes of cows across feeding systems. In the French data, the model adequately simulated the reproductive performance of Holsteins but significantly under-predicted that of Normande cows. In the Scottish data, conception to first service was comparably simulated, whereas interval traits were slightly under-predicted. Selection for greater milk production impaired the reproductive performance and lifespan but not lifetime efficiency. The definition of lifetime efficiency used in this model did not include associated costs or herd-level effects. Further works should include such economic indicators to allow more accurate simulation of lifetime profitability in different production scenarios.

Lifetime prevalence of mood and anxiety disorders in fragile X premutation carriers.

PubMed

Bourgeois, James A; Seritan, Andreea L; Casillas, E Melina; Hessl, David; Schneider, Andrea; Yang, Ying; Kaur, Inderjeet; Cogswell, Jennifer B; Nguyen, Danh V; Hagerman, Randi J

2011-02-01

The authors studied the lifetime prevalence of DSM-IV-TR psychiatric disorders in a population of adults with the fragile X premutation. The Structured Clinical Interview for DSM-IV was conducted, from 2007-2008, in 85 individuals with the fragile X premutation, 47 with the fragile X-associated tremor/ataxia syndrome (FXTAS; 33 male, 14 female; mean age = 66 years) and 38 without FXTAS (16 male, 22 female; mean age = 52 years). Lifetime prevalence for mood and anxiety disorders among carriers with and without FXTAS was compared to available age-specific population estimates from the National Comorbidity Survey Replication (NCS-R). Among participants with FXTAS, 30 (65%) met lifetime DSM-IV-TR criteria for a mood disorder; 24 (52%) met lifetime DSM-IV-TR criteria for an anxiety disorder. Among the non-FXTAS participants, there were 15 instances of lifetime mood disorder (42%) and 18 of lifetime anxiety disorder (47%). When compared to age-specific NCS-R data, the lifetime prevalences of any mood disorder (P < .0001), major depressive disorder (P < .0001), any anxiety disorder (P < .0001), panic disorder (P = .006), specific phobia (P = .0003), and posttraumatic stress disorder (P = .004) were significantly higher in participants with FXTAS. The lifetime rates of social phobia in individuals with the premutation without FXTAS were significantly higher than NCS-R data (P = .001). This sample of carriers of the fragile X premutation had a notably high lifetime risk of mood and anxiety disorders. Mood and anxiety disorders may be part of the clinical phenotype of the fragile X premutation conditions, especially in carriers with FXTAS. Clinicians encountering these patients are advised to consider FXTAS as a neuropsychiatric syndrome as well as a neurologic disorder. © Copyright 2011 Physicians Postgraduate Press, Inc.

Oedema-based model for diffuse low-grade gliomas: application to clinical cases under radiotherapy.

PubMed

Badoual, M; Gerin, C; Deroulers, C; Grammaticos, B; Llitjos, J-F; Oppenheim, C; Varlet, P; Pallud, J

2014-08-01

Diffuse low-grade gliomas are characterized by slow growth. Despite appropriate treatment, they change inexorably into more aggressive forms, jeopardizing the patient's life. Optimizing treatments, for example with the use of mathematical modelling, could help to prevent tumour regrowth and anaplastic transformation. Here, we present a model of the effect of radiotherapy on such tumours. Our objective is to explain observed delay of tumour regrowth following radiotherapy and to predict its duration. We have used a migration-proliferation model complemented by an equation describing appearance and draining of oedema. The model has been applied to clinical data of tumour radius over time, for a population of 28 patients. We were able to show that draining of oedema accounts for regrowth delay after radiotherapy and have been able to fit the clinical data in a robust way. The model predicts strong correlation between high proliferation coefficient and low progression-free gain of lifetime, due to radiotherapy among the patients, in agreement with clinical studies. We argue that, with reasonable assumptions, it is possible to predict (precision ~20%) regrowth delay after radiotherapy and the gain of lifetime due to radiotherapy. Our oedema-based model provides an early estimation of individual duration of tumour response to radiotherapy and thus, opens the door to the possibility of personalized medicine. © 2014 John Wiley & Sons Ltd.

Population trends for North American winter birds based on hierarchical models

USGS Publications Warehouse

Soykan, Candan U.; Sauer, John; Schuetz, Justin G.; LeBaron, Geoffrey S.; Dale, Kathy; Langham, Gary M.

2016-01-01

Managing widespread and persistent threats to birds requires knowledge of population dynamics at large spatial and temporal scales. For over 100 yrs, the Audubon Christmas Bird Count (CBC) has enlisted volunteers in bird monitoring efforts that span the Americas, especially southern Canada and the United States. We employed a Bayesian hierarchical model to control for variation in survey effort among CBC circles and, using CBC data from 1966 to 2013, generated early-winter population trend estimates for 551 species of birds. Selecting a subset of species that do not frequent bird feeders and have ≥25% range overlap with the distribution of CBC circles (228 species) we further estimated aggregate (i.e., across species) trends for the entire study region and at the level of states/provinces, Bird Conservation Regions, and Landscape Conservation Cooperatives. Moreover, we examined the relationship between ten biological traits—range size, population size, migratory strategy, habitat affiliation, body size, diet, number of eggs per clutch, age at sexual maturity, lifespan, and tolerance of urban/suburban settings—and CBC trend estimates. Our results indicate that 68% of the 551 species had increasing trends within the study area over the interval 1966–2013. When trends were examined across the subset of 228 species, the median population trend for the group was 0.9% per year at the continental level. At the regional level, aggregate trends were positive in all but a few areas. Negative population trends were evident in lower latitudes, whereas the largest increases were at higher latitudes, a pattern consistent with range shifts due to climate change. Nine of 10 biological traits were significantly associated with median population trend; however, none of the traits explained >34% of the deviance in the data, reflecting the indirect relationships between population trend estimates and species traits. Trend estimates based on the CBC are broadly congruent with

Single photon counting fluorescence lifetime detection of pericellular oxygen concentrations

NASA Astrophysics Data System (ADS)

Hosny, Neveen A.; Lee, David A.; Knight, Martin M.

2012-01-01

Fluorescence lifetime imaging microscopy offers a non-invasive method for quantifying local oxygen concentrations. However, existing methods are either invasive, require custom-made systems, or show limited spatial resolution. Therefore, these methods are unsuitable for investigation of pericellular oxygen concentrations. This study describes an adaptation of commercially available equipment which has been optimized for quantitative extracellular oxygen detection with high lifetime accuracy and spatial resolution while avoiding systematic photon pile-up. The oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate [Ru(bipy)3]2+, was excited using a two-photon excitation laser. Lifetime was measured using a Becker & Hickl time-correlated single photon counting, which will be referred to as a TCSPC card. [Ru(bipy)3]2+ characterization studies quantified the influences of temperature, pH, cellular culture media and oxygen on the fluorescence lifetime measurements. This provided a precisely calibrated and accurate system for quantification of pericellular oxygen concentration based on measured lifetimes. Using this technique, quantification of oxygen concentrations around isolated viable chondrocytes, seeded in three-dimensional agarose gel, revealed a subpopulation of cells that exhibited significant spatial oxygen gradients such that oxygen concentration reduced with increasing proximity to the cell. This technique provides a powerful tool for quantifying spatial oxygen gradients within three-dimensional cellular models.

Single photon counting fluorescence lifetime detection of pericellular oxygen concentrations.

PubMed

Hosny, Neveen A; Lee, David A; Knight, Martin M

2012-01-01

Fluorescence lifetime imaging microscopy offers a non-invasive method for quantifying local oxygen concentrations. However, existing methods are either invasive, require custom-made systems, or show limited spatial resolution. Therefore, these methods are unsuitable for investigation of pericellular oxygen concentrations. This study describes an adaptation of commercially available equipment which has been optimized for quantitative extracellular oxygen detection with high lifetime accuracy and spatial resolution while avoiding systematic photon pile-up. The oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate [Ru(bipy)(3)](2+), was excited using a two-photon excitation laser. Lifetime was measured using a Becker & Hickl time-correlated single photon counting, which will be referred to as a TCSPC card. [Ru(bipy)(3)](2+) characterization studies quantified the influences of temperature, pH, cellular culture media and oxygen on the fluorescence lifetime measurements. This provided a precisely calibrated and accurate system for quantification of pericellular oxygen concentration based on measured lifetimes. Using this technique, quantification of oxygen concentrations around isolated viable chondrocytes, seeded in three-dimensional agarose gel, revealed a subpopulation of cells that exhibited significant spatial oxygen gradients such that oxygen concentration reduced with increasing proximity to the cell. This technique provides a powerful tool for quantifying spatial oxygen gradients within three-dimensional cellular models.

Comparison of lifetime-based methods for 2D phosphor thermometry in high-temperature environment

NASA Astrophysics Data System (ADS)

Peng, Di; Liu, Yingzheng; Zhao, Xiaofeng; Kim, Kyung Chun

2016-09-01

This paper discusses the currently available techniques for 2D phosphor thermometry, and compares the performance of two lifetime-based methods: high-speed imaging and the dual-gate. High-speed imaging resolves luminescent decay with a fast frame rate, and has become a popular method for phosphor thermometry in recent years. But it has disadvantages such as high equipment cost and long data processing time, and it would fail at sufficiently high temperature due to a low signal-to-noise ratio and short lifetime. The dual-gate method only requires two images on the decay curve and therefore greatly reduces cost in hardware and processing time. A dual-gate method for phosphor thermometry has been developed and compared with the high-speed imaging method through both calibration and a jet impingement experiment. Measurement uncertainty has been evaluated for a temperature range of 473-833 K. The effects of several key factors on uncertainty have been discussed, including the luminescent signal level, the decay lifetime and temperature sensitivity. The results show that both methods are valid for 2D temperature sensing within the given range. The high-speed imaging method shows less uncertainty at low temperatures where the signal level and the lifetime are both sufficient, but its performance is degraded at higher temperatures due to a rapidly reduced signal and lifetime. For T  >  750 K, the dual-gate method outperforms the high-speed imaging method thanks to its superiority in signal-to-noise ratio and temperature sensitivity. The dual-gate method has great potential for applications in high-temperature environments where the high-speed imaging method is not applicable.

Lifetime Assessment of the NEXT Ion Thruster

NASA Technical Reports Server (NTRS)

VanNoord, Jonathan L.

2010-01-01

Ion thrusters are low thrust, high specific impulse devices with required operational lifetimes on the order of 10,000 to 100,000 hr. The NEXT ion thruster is the latest generation of ion thrusters under development. The NEXT ion thruster currently has a qualification level propellant throughput requirement of 450 kg of xenon, which corresponds to roughly 22,000 hr of operation at the highest throttling point. Currently, a NEXT engineering model ion thruster with prototype model ion optics is undergoing a long duration test to determine wear characteristics and establish propellant throughput capability. The NEXT thruster includes many improvements over previous generations of ion thrusters, but two of its component improvements have a larger effect on thruster lifetime. These include the ion optics with tighter tolerances, a masked region and better gap control, and the discharge cathode keeper material change to graphite. Data from the NEXT 2000 hr wear test, the NEXT long duration test, and further analysis is used to determine the expected lifetime of the NEXT ion thruster. This paper will review the predictions for all of the anticipated failure mechanisms. The mechanisms will include wear of the ion optics and cathode s orifice plate and keeper from the plasma, depletion of low work function material in each cathode s insert, and spalling of material in the discharge chamber leading to arcing. Based on the analysis of the NEXT ion thruster, the first failure mode for operation above a specific impulse of 2000 sec is expected to be the structural failure of the ion optics at 750 kg of propellant throughput, 1.7 times the qualification requirement. An assessment based on mission analyses for operation below a specific impulse of 2000 sec indicates that the NEXT thruster is capable of double the propellant throughput required by these missions.

Adding smoking to the Fardal model of cost-effectiveness for the life-time treatment of periodontal diseases.

PubMed

Fardal, Øystein; Grytten, Jostein; Martin, John; Ellingsen, Stig; Fardal, Patrick; Heasman, Peter; Linden, Gerard J

2018-05-16

Little is known about the financial costs that smoking adds to the life-time treatment of periodontal disease. The total life-time cost of periodontal treatment was modelled using data from private periodontal practice. The costs of initial and supportive therapy, re-treatment and tooth replacements (with bridgework or implants) were identified using average dental charges from the American Dental Association survey. Smoking costs at $6 and $10 for 20 cigarettes were compared to the costs of life-time periodontal treatment for stable and unstable compliant patients. Smoking added 8.8% to the financial cost of the life-time cost of periodontal therapy in stable maintenance patients, 40.1% in patients who needed one extra maintenance visit and 71.4% in patients who needed two extra maintenance visits per year in addition to added re-treatment. The cost of smoking far exceeded the cost of periodontal treatment; For patients who smoked 10 to 40 cigarettes per day at the cost of $6 or $10 a pack, the cost of smoking exceeded the cost of life-time periodontal treatment by between 2.7 and 17.9 times. Smoking 40 cigarettes at $10 a packet for 3.4 years would pay for the entire life-time cost of periodontal treatment. Smoking adds considerable extra financial costs to the life-time treatment of periodontal diseases. The cost of smoking itself exceeds the cost of periodontal therapy. This article is protected by copyright. All rights reserved. © 2018 American Academy of Periodontology.

Lifetime and 12-month prevalence estimates for mental disorders in northeastern Germany: findings from the Study of Health in Pomerania.

PubMed

Asselmann, E; Beesdo-Baum, K; Hamm, A; Schmidt, C O; Hertel, J; Grabe, H J; Pané-Farré, C A

2018-06-15

Few epidemiological studies presented 12-month and lifetime prevalence estimates for DSM-IV mental disorders in the adult general population by sex and age up to very old age. From 2007 to 2010, DSM-IV mental disorders were assessed with the DIA-X/M-CIDI among N = 2400 participants (aged 29-89 years) from the Study of Health in Pomerania, an epidemiological study based on a two-stage stratified cluster sample randomly drawn from the adult general population in northeastern Germany. 36.3% of the sample was affected by any 12-month and 54.8% by any lifetime mental disorder. The most frequent diagnostic groups were anxiety (12-month: 14.8%, lifetime: 23.4%), substance use (12-month: 14.5%, lifetime: 25.0%), somatoform (12-month: 12.9%, lifetime: 20.4%) and depressive (12-month: 7.3%, lifetime: 18.6%) disorders. Except for substance use (higher prevalence in men) and bipolar disorders (comparable prevalence in men and women), higher 12-month and lifetime prevalence estimates were found in women vs. men. Moreover, lower 12-month and lifetime prevalence estimates were found in older (aged 60-74 or 75-89 years) vs. younger (aged 29-44 or 45-59 years) age groups. 22.6% (men: 21.1%, women: 23.9%) of those affected by any 12-month disorder met criteria for two and 13.6% (men: 9.6%, women: 16.9%) for three or more 12-month diagnoses. Similarly, 26.4% (men: 25.7%, women: 26.9%) of those affected by any lifetime disorder met criteria for two and 22.7% (men: 19.6%, women: 25.2%) for three or more lifetime diagnoses. Our findings demonstrate the frequency of mental disorders in northeastern Germany and emphasize the need for continued prevention and intervention efforts.

Agile Model Driven Development of Electronic Health Record-Based Specialty Population Registries

PubMed Central

Kannan, Vaishnavi; Fish, Jason C.; Willett, DuWayne L.

2018-01-01

The transformation of the American healthcare payment system from fee-for-service to value-based care increasingly makes it valuable to develop patient registries for specialized populations, to better assess healthcare quality and costs. Recent widespread adoption of Electronic Health Records (EHRs) in the U.S. now makes possible construction of EHR-based specialty registry data collection tools and reports, previously unfeasible using manual chart abstraction. But the complexities of specialty registry EHR tools and measures, along with the variety of stakeholders involved, can result in misunderstood requirements and frequent product change requests, as users first experience the tools in their actual clinical workflows. Such requirements churn could easily stall progress in specialty registry rollout. Modeling a system’s requirements and solution design can be a powerful way to remove ambiguities, facilitate shared understanding, and help evolve a design to meet newly-discovered needs. “Agile Modeling” retains these values while avoiding excessive unused up-front modeling in favor of iterative incremental modeling. Using Agile Modeling principles and practices, in calendar year 2015 one institution developed 58 EHR-based specialty registries, with 111 new data collection tools, supporting 134 clinical process and outcome measures, and enrolling over 16,000 patients. The subset of UML and non-UML models found most consistently useful in designing, building, and iteratively evolving EHR-based specialty registries included User Stories, Domain Models, Use Case Diagrams, Decision Trees, Graphical User Interface Storyboards, Use Case text descriptions, and Solution Class Diagrams. PMID:29750222

Multimodel Estimates of Atmospheric Lifetimes of Long-lived Ozone-Depleting Substances: Present and Future

NASA Technical Reports Server (NTRS)

Chipperfield, M. P.; Liang, Q.; Strahan, S. E.; Morgenstern, O.; Dhomse, S. S.; Abraham, N. L.; Archibald, A. T.; Bekki, S.; Braesicke, P.; Di Genova, G.;

Multimodel Estimates of Atmospheric Lifetimes of Long-Lived Ozone-Depleting Substances: Present and Future

NASA Technical Reports Server (NTRS)

Chipperfield, M. P.; Liang, Q.; Strahan, S. E.; Morgenstern, O.; Dhomse, S. S.; Abraham, N. L.; Archibald, A. T.; Bekki, S.; Braesicke, P.; Di Genova, G.;

Optical damage performance of conductive widegap semiconductors: spatial, temporal, and lifetime modeling

DOE PAGES

Elhadj, Selim; Yoo, Jae-hyuck; Negres, Raluca A.; ...

2016-12-19

The optical damage performance of electrically conductive gallium nitride (GaN) and indium tin oxide (ITO) films is addressed using large area, high power laser beam exposures at 1064 nm sub-bandgap wavelength. Analysis of the laser damage process assumes that onset of damage (threshold) is determined by the absorption and heating of a nanoscale region of a characteristic size reaching a critical temperature. We use this model to rationalize semi-quantitatively the pulse width scaling of the damage threshold from picosecond to nanosecond timescales, along with the pulse width dependence of the damage threshold probability derived by fitting large beam damage densitymore » data. Multi-shot exposures were used to address lifetime performance degradation described by an empirical expression based on the single exposure damage model. A damage threshold degradation of at least 50% was observed for both materials. Overall, the GaN films tested had 5-10 × higher optical damage thresholds than the ITO films tested for comparable transmission and electrical conductivity. This route to optically robust, large aperture transparent electrodes and power optoelectronics may thus involve use of next generation widegap semiconductors such as GaN.« less

Long-term economic benefits attributed to IVF-conceived children: a lifetime tax calculation.

PubMed

Connolly, Mark P; Pollard, Michael S; Hoorens, Stijn; Kaplan, Brian R; Oskowitz, Selwyn P; Silber, Sherman J

2008-09-01

To evaluate whether lifetime future net tax revenues from an in vitro fertilization (IVF)-conceived child are substantial enough to warrant public subsidy relative to the mean IVF treatment costs required to obtain 1 live birth. Mathematical generational accounting model. The model estimates direct financial interactions between the IVF-conceived child and the government during the child's projected lifetime. In the model, we accrue IVF costs required to conceive the child to the government, and then we estimate future net tax revenue to the federal and state governments from this individual, offset by direct financial transfers from the government (eg, child allowances, education, Medicare, and Social Security). We discount lifetime costs and gross tax payments at Treasury Department rates to establish the present value of investing in IVF. We applied US Congressional Budget Office projected changes in tax rates over the course of the model. An IVF-conceived child, average in every respect (eg, future earnings, healthcare consumption, and life expectancy), represents a net positive return to the government. Based on an average employed individual born in 2005, the projected net lifetime tax contribution is US $606,200. Taking into consideration IVF costs and all direct financial interactions, the net present value is US $155,870. Lifetime net taxes paid from a child relative to the child's initial IVF investment represent a 700% net return to the government in discounted US dollars from fully employed individuals. This suggests that removing barriers to IVF would have positive tax benefits for the government, notwithstanding its beneficial effect on overall economic growth.

Lifetime measurements in shape transition nucleus 188Pt

NASA Astrophysics Data System (ADS)

Rohilla, Aman; Gupta, C. K.; Singh, R. P.; Muralithar, S.; Chakraborty, S.; Sharma, H. P.; Kumar, A.; Govil, I. M.; Biswas, D. C.; Chamoli, S. K.

2017-04-01

Nuclear level lifetimes of high spin states in yrast and non-yrast bands of 188Pt nucleus have been measured using recoil distance plunger setup present at IUAC, Delhi. In the experiment nuclear states of interest were populated via 174Yb(18O,4 n)188Pt reaction at a beam energy of 79MeV provided by 15 UD Pelletron accelerator. The extracted B(E2\\downarrow) values show an initial rise up to 4+ state and then a nearly constant behavior with spin along yrast band, indicating change of nuclear structure in 188Pt at low spins. The good agreement between experimental and TPSM model B(E2\\downarrow) values up to 4^+ state suggests an increase in axial deformation of the nucleus. The average absolute β2 = 0.20 (3) obtained from measured B(E2\\downarrow) values matches well the values predicted by CHFB and IBM calculations for oblate ( β2 ˜ -0.19) and prolate (β2 ˜ 0.22) shapes. As the lifetime measurements do not yield the sign of β2, no definite conclusion can be drawn on the prolate or oblate collectivity of 188Pt on the basis of present measurements.

Towards sensitive, high-throughput, biomolecular assays based on fluorescence lifetime

NASA Astrophysics Data System (ADS)

Ioanna Skilitsi, Anastasia; Turko, Timothé; Cianfarani, Damien; Barre, Sophie; Uhring, Wilfried; Hassiepen, Ulrich; Léonard, Jérémie

2017-09-01

Time-resolved fluorescence detection for robust sensing of biomolecular interactions is developed by implementing time-correlated single photon counting in high-throughput conditions. Droplet microfluidics is used as a promising platform for the very fast handling of low-volume samples. We illustrate the potential of this very sensitive and cost-effective technology in the context of an enzymatic activity assay based on fluorescently-labeled biomolecules. Fluorescence lifetime detection by time-correlated single photon counting is shown to enable reliable discrimination between positive and negative control samples at a throughput as high as several hundred samples per second.

Lifetime income patterns and alcohol consumption: Investigating the association between long- and short-term income trajectories and drinking

PubMed Central

Cerdá, Magdalena; Johnson-Lawrence, Vicki; Galea, Sandro

2011-01-01

Lifetime patterns of income may be an important driver of alcohol use. In this study, we evaluated the relationship between long-term and short-term measures of income and the relative odds of abstaining, drinking lightly-moderately and drinking heavily. We used data from the US Panel Study on Income Dynamics (PSID), a national population-based cohort that has been followed annually or biannually since 1968. We examined 3111 adult respondents aged 30-44 in 1997. Latent class growth mixture models with a censored normal distribution were used to estimate income trajectories followed by the respondent families from 1968-1997, while repeated measures multinomial generalized logit models estimated the odds of abstinence (no drinks per day) or heavy drinking (at least 3 drinks a day), relative to light/moderate drinking (<1-2 drinks a day), in 1999-2003. Lower income was associated with higher odds of abstinence and of heavy drinking, relative to light/moderate drinking. For example, belonging to a household with stable low income ($11-20,000) over 30 years was associated with 1.57 odds of abstinence, and 2.14 odds of heavy drinking in adulthood. The association between lifetime income patterns and alcohol use decreased in magnitude and became non-significant once we controlled for past-year income, education and occupation. Lifetime income patterns may have an indirect association with alcohol use, mediated through current socioeconomic conditions. PMID:21890256

Measurement of lifetimes in Fe,6462,Co,6361 , and 59Mn

NASA Astrophysics Data System (ADS)

Klintefjord, M.; Ljungvall, J.; Görgen, A.; Lenzi, S. M.; Bello Garrote, F. L.; Blazhev, A.; Clément, E.; de France, G.; Delaroche, J.-P.; Désesquelles, P.; Dewald, A.; Doherty, D. T.; Fransen, C.; Gengelbach, A.; Georgiev, G.; Girod, M.; Goasduff, A.; Gottardo, A.; Hadyńska-KlÈ©k, K.; Jacquot, B.; Konstantinopoulos, T.; Korichi, A.; Lemasson, A.; Libert, J.; Lopez-Martens, A.; Michelagnoli, C.; Navin, A.; Nyberg, J.; Pérez-Vidal, R. M.; Roccia, S.; Sahin, E.; Stefan, I.; Stuchbery, A. E.; Zielińska, M.; Barrientos, D.; Birkenbach, B.; Boston, A.; Charles, L.; Ciemala, M.; Dudouet, J.; Eberth, J.; Gadea, A.; González, V.; Harkness-Brennan, L.; Hess, H.; Jungclaus, A.; Korten, W.; Menegazzo, R.; Mengoni, D.; Million, B.; Pullia, A.; Ralet, D.; Recchia, F.; Reiter, P.; Salsac, M. D.; Sanchis, E.; Stezowski, O.; Theisen, Ch.; Valiente Dobon, J. J.

2017-02-01

Lifetimes of the 41+ states in Fe,6462 and the 11 /21- states in Co,6361 and 59Mn were measured at the Grand Accélérateur National d'Ions Lourds (GANIL) facility by using the Advanced Gamma Tracking Array (AGATA) and the large-acceptance variable mode spectrometer (VAMOS++). The states were populated through multinucleon transfer reactions with a 238U beam impinging on a 64Ni target, and lifetimes in the picosecond range were measured by using the recoil distance Doppler shift method. The data show an increase of collectivity in the iron isotopes approaching N =40 . The reduction of the subshell gap between the ν 2 p1 /2 and ν 1 g9 /2 orbitals leads to an increased population of the quasi-SU(3) pair (ν 1 g9 /2,ν 2 d5 /2 ), which causes an increase in quadrupole collectivity. This is not observed for the cobalt isotopes with N <40 for which the neutron subshell gap is larger due to the repulsive monopole component of the tensor nucleon-nucleon interaction. The extracted experimental B (E 2 ) values are compared with large-scale shell-model calculations and with beyond-mean-field calculations with the Gogny D1S interaction. A good agreement between calculations and experimental values is found, and the results demonstrate in particular the spectroscopic quality of the Lenzi, Nowacki, Poves, and Sieja (LNPS) shell-model interaction.

Measuring the free neutron lifetime to <= 0.3s via the beam method

NASA Astrophysics Data System (ADS)

Fomin, Nadia

2017-09-01

Neutron beta decay is an archetype for all semi-leptonic charged-current weak processes. While of interest as a fundamental particle property, a precise value for the neutron lifetime is also required for consistency tests of the Standard Model as well as to calculate the primordial 4He abundance in Big Bang Nucleosynthesis models. An effort has begun to develop an in-beam measurement of the neutron lifetime with a projected <= 0.3s uncertainty. This effort is part of a phased campaign of neutron lifetime measurements based at the NIST Center for Neutron Research, using the Sussex-ILL-NIST technique. Recent advances in neutron fluence measurement techniques as well as new large area silicon detector technology address the two largest sources of uncertainty of in-beam measurements, paving the way for a new measurement. The experimental design and projected uncertainties for the 0.3s measurement will be discussed.

Lifetime maps for orbits around Callisto using a double-averaged model

NASA Astrophysics Data System (ADS)

Cardoso dos Santos, Josué; Carvalho, Jean P. S.; Prado, Antônio F. B. A.; Vilhena de Moraes, Rodolpho

2017-12-01

The present paper studies the lifetime of orbits around a moon that is in orbit around its mother planet. In the context of the inner restricted three-body problem, the dynamical model considered in the present study uses the double-averaged dynamics of a spacecraft moving around a moon under the gravitational pulling of a disturbing third body in an elliptical orbit. The non-uniform distribution of the mass of the moon is also considered. Applications are performed using numerical experiments for the Callisto-spacecraft-Jupiter system, and lifetime maps for different values of the eccentricity of the disturbing body (Jupiter) are presented, in order to investigate the role of this parameter in these maps. The idea is to simulate a system with the same physical parameters as the Jupiter-Callisto system, but with larger eccentricities. These maps are also useful for validation and improvements in the results available in the literature, such as to find conditions to extend the available time for a massless orbiting body to be in highly inclined orbits under gravitational disturbances coming from the other bodies of the system.

Lifetime measurement of high spin states in (75) Kr

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

Sheikh, Javid; Trivedi, T.; Maurya, K.

2010-01-01

The lifetimes of high spin states of {sup 75}Kr have been determined via {sup 50}Cr ({sup 28}Si, 2pn) {sup 75}Kr reaction in positive parity band using the Doppler-shift attenuation method. The transition quadrupole moments Q deduced from lifetime measurements have been compared with {sup 75}Br. Experimental results obtained from lifetime measurement are interpreted in the framework of projected shell model.

Entrainment and Control of Bacterial Populations: An in Silico Study over a Spatially Extended Agent Based Model.

PubMed

Mina, Petros; Tsaneva-Atanasova, Krasimira; Bernardo, Mario di

2016-07-15

We extend a spatially explicit agent based model (ABM) developed previously to investigate entrainment and control of the emergent behavior of a population of synchronized oscillating cells in a microfluidic chamber. Unlike most of the work in models of control of cellular systems which focus on temporal changes, we model individual cells with spatial dependencies which may contribute to certain behavioral responses. We use the model to investigate the response of both open loop and closed loop strategies, such as proportional control (P-control), proportional-integral control (PI-control) and proportional-integral-derivative control (PID-control), to heterogeinities and growth in the cell population, variations of the control parameters and spatial effects such as diffusion in the spatially explicit setting of a microfluidic chamber setup. We show that, as expected from the theory of phase locking in dynamical systems, open loop control can only entrain the cell population in a subset of forcing periods, with a wide variety of dynamical behaviors obtained outside these regions of entrainment. Closed-loop control is shown instead to guarantee entrainment in a much wider region of control parameter space although presenting limitations when the population size increases over a certain threshold. In silico tracking experiments are also performed to validate the ability of classical control approaches to achieve other reference behaviors such as a desired constant output or a linearly varying one. All simulations are carried out in BSim, an advanced agent-based simulator of microbial population which is here extended ad hoc to include the effects of control strategies acting onto the population.

Lifetime measurements using the recoil distance method—achievements and perspectives

NASA Astrophysics Data System (ADS)

Krücken, R.

2001-07-01

The recoil distance method (RDM) for measuring pico-second nuclear level lifetimes and its use in nuclear structure studies is reviewed and perspectives for the future are presented. High precision measurements in the mass-130 region, studies of multi-phonon states in rare earth nuclei, the investigation of shape coexistence and the recently discovered phenomenon of "magnetic rotation" are reviewed. Prospects for lifetime measurements in exotic regions of nuclei such as the measurement of lifetimes in neutron rich nuclei populated via spontaneous and heavy-ion induced fission are discussed. Other prospects include the use of the RDM technique in conjunction with recoil separators. The relevance of these techniques for experiments with radioactive ion beams will be discussed.

Lifetime measurement of neutron-rich even-even molybdenum isotopes

NASA Astrophysics Data System (ADS)

Ralet, D.; Pietri, S.; Rodríguez, T.; Alaqeel, M.; Alexander, T.; Alkhomashi, N.; Ameil, F.; Arici, T.; Ataç, A.; Avigo, R.; Bäck, T.; Bazzacco, D.; Birkenbach, B.; Boutachkov, P.; Bruyneel, B.; Bruce, A. M.; Camera, F.; Cederwall, B.; Ceruti, S.; Clément, E.; Cortés, M. L.; Curien, D.; De Angelis, G.; Désesquelles, P.; Dewald, M.; Didierjean, F.; Domingo-Pardo, C.; Doncel, M.; Duchêne, G.; Eberth, J.; Gadea, A.; Gerl, J.; Ghazi Moradi, F.; Geissel, H.; Goigoux, T.; Goel, N.; Golubev, P.; González, V.; Górska, M.; Gottardo, A.; Gregor, E.; Guastalla, G.; Givechev, A.; Habermann, T.; Hackstein, M.; Harkness-Brennan, L.; Henning, G.; Hess, H.; Hüyük, T.; Jolie, J.; Judson, D. S.; Jungclaus, A.; Knoebel, R.; Kojouharov, I.; Korichi, A.; Korten, W.; Kurz, N.; Labiche, M.; Lalović, N.; Louchart-Henning, C.; Mengoni, D.; Merchán, E.; Million, B.; Morales, A. I.; Napoli, D.; Naqvi, F.; Nyberg, J.; Pietralla, N.; Podolyák, Zs.; Pullia, A.; Prochazka, A.; Quintana, B.; Rainovski, G.; Reese, M.; Recchia, F.; Reiter, P.; Rudolph, D.; Salsac, M. D.; Sanchis, E.; Sarmiento, L. G.; Schaffner, H.; Scheidenberger, C.; Sengele, L.; Singh, B. S. Nara; Singh, P. P.; Stahl, C.; Stezowski, O.; Thoele, P.; Valiente Dobon, J. J.; Weick, H.; Wendt, A.; Wieland, O.; Winfield, J. S.; Wollersheim, H. J.; Zielinska, M.; PreSPEC Collaboration

2017-03-01

Background: In the neutron-rich A ≈100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A =100 up to mass A =108 , and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the γ ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a γ -ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A =100 to A =108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: τ =29 .7-9.1+11.3 ps for the 4+ state of 108Mo and τ =3 .2-0.7+0.7 ps for the 6+ state of 102Mo. Conclusions: The reduced transition strengths B (E 2 ) , calculated from lifetimes measured in this experiment, compared to beyond

A systems approach to healthcare: agent-based modeling, community mental health, and population well-being.

PubMed

Silverman, Barry G; Hanrahan, Nancy; Bharathy, Gnana; Gordon, Kim; Johnson, Dan

2015-02-01

Explore whether agent-based modeling and simulation can help healthcare administrators discover interventions that increase population wellness and quality of care while, simultaneously, decreasing costs. Since important dynamics often lie in the social determinants outside the health facilities that provide services, this study thus models the problem at three levels (individuals, organizations, and society). The study explores the utility of translating an existing (prize winning) software for modeling complex societal systems and agent's daily life activities (like a Sim City style of software), into a desired decision support system. A case study tests if the 3 levels of system modeling approach is feasible, valid, and useful. The case study involves an urban population with serious mental health and Philadelphia's Medicaid population (n=527,056), in particular. Section 3 explains the models using data from the case study and thereby establishes feasibility of the approach for modeling a real system. The models were trained and tuned using national epidemiologic datasets and various domain expert inputs. To avoid co-mingling of training and testing data, the simulations were then run and compared (Section 4.1) to an analysis of 250,000 Philadelphia patient hospital admissions for the year 2010 in terms of re-hospitalization rate, number of doctor visits, and days in hospital. Based on the Student t-test, deviations between simulated vs. real world outcomes are not statistically significant. Validity is thus established for the 2008-2010 timeframe. We computed models of various types of interventions that were ineffective as well as 4 categories of interventions (e.g., reduced per-nurse caseload, increased check-ins and stays, etc.) that result in improvement in well-being and cost. The 3 level approach appears to be useful to help health administrators sort through system complexities to find effective interventions at lower costs. Copyright © 2014 Elsevier B

Atmospheric Muon Lifetime, Standard Model of Particles and the Lead Stopping Power for Muons

NASA Astrophysics Data System (ADS)

Gutarra-Leon, Angel; Barazandeh, Cioli; Majewski, Walerian

2017-01-01

The muon is a fundamental particles of matter. It decays into three other leptons through an exchange of the weak vector bosons W +/W-. Muons are present in the atmosphere from cosmic ray showers. By detecting the time delay between arrival of the muon and an appearance of the decay electron in our detector, we'll measure muon's lifetime at rest. From the lifetime we should be able to find the ratio gw /MW of the weak coupling constant gw (a weak analog of the electric charge) to the mass of the W-boson MW. Vacuum expectation value v of the Higg's field, which determines the masses of all particles of the Standard Model (SM), could be then calculated from our muon experiment as v =2MWc2/gw =(τ m μc2/6 π3ĥ)1/4m μc2 in terms of muon mass mµand muon lifetime τ only. Using known experimental value for MWc2 = 80.4 GeV we'll find the weak coupling constant gw. Using the SM relation e =gwsin θ√ hc ɛ0 with the experimental value of the Z0-photon weak mixing angle θ = 29o we could find from our muon lifetime the value of the elementary electric charge e. We'll determine the sea-level fluxes of low-energy and high-energy cosmic muons, then we'll shield the detector with varying thicknesses of lead plates and find the energy-dependent muon stopping power in lead.

Atmospheric lifetime of SF5CF3

NASA Astrophysics Data System (ADS)

Takahashi, K.; Nakayama, T.; Matsumi, Y.; Solomon, S.; Gejo, T.; Shigemasa, E.; Wallington, T. J.

2002-08-01

The vacuum ultraviolet (VUV) absorption spectrum of SF5CF3 was measured over the range 106-200 nm. At 121.6 nm, σ(base e) = (7.8 +/- 0.6) × 10-18 cm2 molecule-1, in which quoted uncertainty includes two standard deviation from the least-square fit in the Beer-Lambert plot and our estimate of potential systematic errors associated with measurements of the reactant concentrations. The VUV spectrum and literature data for electron attachment and ion-molecule reactions were incorporated into a model of the stratosphere, mesosphere, and lower thermosphere. This information provides better constraints on the atmospheric lifetime and hence on the potential of this highly radiatively-active trace gas to influence the climate system. The atmospheric lifetime of SF5CF3 is dominated by dissociative electron attachment and is estimated to be approximately 950 years. Solar proton events could reduce this to a lower limit of 650 years.

Benefits and costs of substance abuse treatment programs for state prison inmates: results from a lifetime simulation model.

PubMed

Zarkin, Gary A; Cowell, Alexander J; Hicks, Katherine A; Mills, Michael J; Belenko, Steven; Dunlap, Laura J; Houser, Kimberly A; Keyes, Vince

2012-06-01

Reflecting drug use patterns and criminal justice policies throughout the 1990s and 2000s, prisons hold a disproportionate number of society's drug abusers. Approximately 50% of state prisoners meet the criteria for a diagnosis of drug abuse or dependence, but only 10% receive medically based drug treatment. Because of the link between substance abuse and crime, treating substance abusing and dependent state prisoners while incarcerated has the potential to yield substantial economic benefits. In this paper, we simulate the lifetime costs and benefits of improving prison-based substance abuse treatment and post-release aftercare for a cohort of state prisoners. Our model captures the dynamics of substance abuse as a chronic disease; estimates the benefits of substance abuse treatment over individuals' lifetimes; and tracks the costs of crime and criminal justice costs related to policing, adjudication, and incarceration. We estimate net societal benefits and cost savings to the criminal justice system of the current treatment system and five policy scenarios. We find that four of the five policy scenarios provide positive net societal benefits and cost savings to the criminal justice system relative to the current treatment system. Our study demonstrates the societal gains to improving the drug treatment system for state prisoners. Copyright © 2011 John Wiley & Sons, Ltd.

BENEFITS AND COSTS OF SUBSTANCE ABUSE TREATMENT PROGRAMS FOR STATE PRISON INMATES: RESULTS FROM A LIFETIME SIMULATION MODEL

PubMed Central

ZARKIN, GARY A.; COWELL, ALEXANDER J.; HICKS, KATHERINE A.; MILLS, MICHAEL J.; BELENKO, STEVEN; DUNLAP, LAURA J.; HOUSER, KIMBERLY A.; KEYES, VINCE

2011-01-01

SUMMARY Reflecting drug use patterns and criminal justice policies throughout the 1990s and 2000s, prisons hold a disproportionate number of society’s drug abusers. Approximately 50% of state prisoners meet the criteria for a diagnosis of drug abuse or dependence, but only 10% receive medically based drug treatment. Because of the link between substance abuse and crime, treating substance abusing and dependent state prisoners while incarcerated has the potential to yield substantial economic benefits. In this paper, we simulate the lifetime costs and benefits of improving prison-based substance abuse treatment and post-release aftercare for a cohort of state prisoners. Our model captures the dynamics of substance abuse as a chronic disease; estimates the benefits of substance abuse treatment over individuals’ lifetimes; and tracks the costs of crime and criminal justice costs related to policing, adjudication, and incarceration. We estimate net societal benefits and cost savings to the criminal justice system of the current treatment system and five policy scenarios. We find that four of the five policy scenarios provide positive net societal benefits and cost savings to the criminal justice system relative to the current treatment system. Our study demonstrates the societal gains to improving the drug treatment system for state prisoners. PMID:21506193

Infrared Radiative Forcing and Atmospheric Lifetimes of Trace Species Based on Observations from UARS

NASA Technical Reports Server (NTRS)

Minschwaner, K.; Carver, R. W.; Briegleb, B. P.

1997-01-01

Observations from instruments on the Upper Atmosphere Research Satellite (UARS) have been used to constrain calculations of infrared radiative forcing by CH4, CCl2F2 and N2O, and to determine lifetimes Of CCl2F2 and N2O- Radiative forcing is calculated as a change in net infrared flux at the tropopause that results from an increase in trace gas amount from pre-industrial (1750) to contemporary (1992) times. Latitudinal and seasonal variations are considered explicitly, using distributions of trace gases and temperature in the stratosphere from UARS measurements and seasonally averaged cloud statistics from the International Satellite Cloud Climatology Project. Top-of-atmosphere fluxes calculated for the contemporary period are in good agreement with satellite measurements from the Earth Radiation Budget Experiment. Globally averaged values of the radiative forcing are 0.536, 0.125, and 0.108 W m-2 for CH4, CCl2F2, and N2O, respectively. The largest forcing occurs near subtropical latitudes during summer, predominantly as a result of the combination of cloud-free skies and a high, cold tropopause. Clouds are found to play a significant role in regulating infrared forcing, reducing the magnitude of the forcing by 30-40% compared to the case of clear skies. The vertical profile of CCl2F2 is important in determining its radiative forcing; use of a height-independent mixing ratio in the stratosphere leads to an over prediction of the forcing by 10%. The impact of stratospheric profiles on radiative forcing by CH4 and N2O is less than 2%. UARS-based distributions of CCl2F2 and N2O are used also to determine global destruction rates and instantaneous lifetimes of these gases. Rates of photolytic destruction in the stratosphere are calculated using solar ultraviolet irradiances measured on UARS and a line-by-line model of absorption in the oxygen Schumann-Runge bands. Lifetimes are 114 +/- 22 and 118 +/- 25 years for CCl2F2 and N2O, respectively.

Projected rates of psychological disorders and suicidality among soldiers based on simulations of matched general population data

PubMed Central

Gadermann, Anne M.; Gilman, Stephen E.; McLaughlin, Katie A.; Nock, Matthew K.; Petukhova, Maria; Sampson, Nancy A.; Kessler, Ronald C.

2014-01-01

Limited data are available on lifetime prevalence and age-of-onset distributions of psychological disorders and suicidal behaviors among Army personnel. We used simulation methods to approximate such estimates based on analysis of data from a U.S. national general population survey with the socio-demographic profile of U.S. Army personnel. Estimated lifetime prevalence of any DSM-IV anxiety, mood, behavior, or substance disorder in this sample was 53.1 percent (17.7 percent for mood disorders, 27.2 percent for anxiety disorders, 22.7 percent for behavior disorders, and 14.4 percent for substance disorders). The vast majority of cases had onsets prior to the expected age-of-enlistment if they were in the Army (91.6 percent). Lifetime prevalence was 14.2 percent for suicidal ideation, 5.4 percent for suicide plans, and 4.5 percent for suicide attempts. The proportion of estimated pre-enlistment onsets was between 68.4 percent (suicide plans) and 82.4 percent (suicidal ideation). Externalizing disorders with onsets prior to expected age-of-enlistment and internalizing disorders with onsets after expected age-of-enlistment significantly predicted post-enlistment suicide attempts, with population attributable risk proportions of 41.8 percent and 38.8 percent, respectively. Implications of these findings are discussed for interventions designed to screen, detect, and treat psychological disorders and suicidality in the Army. PMID:23025127

A portable time-domain LED fluorimeter for nanosecond fluorescence lifetime measurements

NASA Astrophysics Data System (ADS)

Wang, Hongtao; Qi, Ying; Mountziaris, T. J.; Salthouse, Christopher D.

2014-05-01

Fluorescence lifetime measurements are becoming increasingly important in chemical and biological research. Time-domain lifetime measurements offer fluorescence multiplexing and improved handling of interferers compared with the frequency-domain technique. In this paper, an all solid-state, filterless, and highly portable light-emitting-diode based time-domain fluorimeter (LED TDF) is reported for the measurement of nanosecond fluorescence lifetimes. LED based excitation provides more wavelengths options compared to laser diode based excitation, but the excitation is less effective due to the uncollimated beam, less optical power, and longer latency in state transition. Pulse triggering and pre-bias techniques were implemented in our LED TDF to improve the peak optical power to over 100 mW. The proposed pulsing circuit achieved an excitation light fall time of less than 2 ns. Electrical resetting technique realized a time-gated photo-detector to remove the interference of the excitation light with fluorescence. These techniques allow the LED fluorimeter to accurately measure the fluorescence lifetime of fluorescein down to concentration of 0.5 μM. In addition, all filters required in traditional instruments are eliminated for the non-attenuated excitation/emission light power. These achievements make the reported device attractive to biochemical laboratories seeking for highly portable lifetime detection devices for developing sensors based on fluorescence lifetime changes. The device was initially validated by measuring the lifetimes of three commercial fluorophores and comparing them with reported lifetime data. It was subsequently used to characterize a ZnSe quantum dot based DNA sensor.

A portable time-domain LED fluorimeter for nanosecond fluorescence lifetime measurements

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

Wang, Hongtao; Salthouse, Christopher D., E-mail: salthouse@ecs.umass.edu; Center for Personalized Health Monitoring, University of Massachusetts, Amherst, Massachusetts 01003

2014-05-15

Fluorescence lifetime measurements are becoming increasingly important in chemical and biological research. Time-domain lifetime measurements offer fluorescence multiplexing and improved handling of interferers compared with the frequency-domain technique. In this paper, an all solid-state, filterless, and highly portable light-emitting-diode based time-domain fluorimeter (LED TDF) is reported for the measurement of nanosecond fluorescence lifetimes. LED based excitation provides more wavelengths options compared to laser diode based excitation, but the excitation is less effective due to the uncollimated beam, less optical power, and longer latency in state transition. Pulse triggering and pre-bias techniques were implemented in our LED TDF to improve themore » peak optical power to over 100 mW. The proposed pulsing circuit achieved an excitation light fall time of less than 2 ns. Electrical resetting technique realized a time-gated photo-detector to remove the interference of the excitation light with fluorescence. These techniques allow the LED fluorimeter to accurately measure the fluorescence lifetime of fluorescein down to concentration of 0.5 μM. In addition, all filters required in traditional instruments are eliminated for the non-attenuated excitation/emission light power. These achievements make the reported device attractive to biochemical laboratories seeking for highly portable lifetime detection devices for developing sensors based on fluorescence lifetime changes. The device was initially validated by measuring the lifetimes of three commercial fluorophores and comparing them with reported lifetime data. It was subsequently used to characterize a ZnSe quantum dot based DNA sensor.« less

A statistical framework for the validation of a population exposure model based on personal exposure data

NASA Astrophysics Data System (ADS)

Rodriguez, Delphy; Valari, Myrto; Markakis, Konstantinos; Payan, Sébastien

2016-04-01

Currently, ambient pollutant concentrations at monitoring sites are routinely measured by local networks, such as AIRPARIF in Paris, France. Pollutant concentration fields are also simulated with regional-scale chemistry transport models such as CHIMERE (http://www.lmd.polytechnique.fr/chimere) under air-quality forecasting platforms (e.g. Prev'Air http://www.prevair.org) or research projects. These data may be combined with more or less sophisticated techniques to provide a fairly good representation of pollutant concentration spatial gradients over urban areas. Here we focus on human exposure to atmospheric contaminants. Based on census data on population dynamics and demographics, modeled outdoor concentrations and infiltration of outdoor air-pollution indoors we have developed a population exposure model for ozone and PM2.5. A critical challenge in the field of population exposure modeling is model validation since personal exposure data are expensive and therefore, rare. However, recent research has made low cost mobile sensors fairly common and therefore personal exposure data should become more and more accessible. In view of planned cohort field-campaigns where such data will be available over the Paris region, we propose in the present study a statistical framework that makes the comparison between modeled and measured exposures meaningful. Our ultimate goal is to evaluate the exposure model by comparing modeled exposures to monitor data. The scientific question we address here is how to downscale modeled data that are estimated on the county population scale at the individual scale which is appropriate to the available measurements. To assess this question we developed a Bayesian hierarchical framework that assimilates actual individual data into population statistics and updates the probability estimate.

Spin Lifetimes in III-V Semiconductor Heterostructures Originating from Zincblende Symmetry

NASA Astrophysics Data System (ADS)

Lau, Wayne; Olesberg, Jon; Flatté, Michael

2000-03-01

Electron spin relaxation in zincblende type semiconductors at room temperature is dominated by the D'yakonov-Perel' mechanism (DP), which is a direct result of the spin splitting of the conduction band due to the bulk inversion asymmetry (BIA) of zincblende materials. To accurately describe the DP spin relaxation mechanism in quantum wells we employ a heterostructure model based on a fourteen bulk band basis, which accounts for the zincblende symmetry of the heterostructure constituents. Electron spin lifetimes are calculated for 75Å n-doped GaAs/Al_0.4Ga_0.6As quantum wells at room temperature. Excellent agreement between theory and experiments is found. In contrast, the calculated spin lifetimes based on the D'yakonov-Kachorovskii theory are an order magnitude shorter than the experimental values. The spin splitting and spin lifetime in no common atom In_0.53Ga_0.47As/InP quantum wells are also investigated. The contribution to the conduction subband spin splitting is dominated by the native interface asymmetry (NIA) mechanism for thin quantum wells; while the spin splitting is governed by the BIA mechanism for thick quantum wells. We find that BIA provides a satisfactory explanation for the spin lifetime measured in an In_0.53Ga_0.47As/InP quantum well with a 97Å barrier and a 70Å well at room temperature.

Development of a dynamic framework to explain population patterns of leisure-time physical activity through agent-based modeling.

PubMed

Garcia, Leandro M T; Diez Roux, Ana V; Martins, André C R; Yang, Yong; Florindo, Alex A

2017-08-22

Despite the increasing body of evidences on the factors influencing leisure-time physical activity, our understanding of the mechanisms and interactions that lead to the formation and evolution of population patterns is still limited. Moreover, most frameworks in this field fail to capture dynamic processes. Our aim was to create a dynamic conceptual model depicting the interaction between key psychological attributes of individuals and main aspects of the built and social environments in which they live. This conceptual model will inform and support the development of an agent-based model aimed to explore how population patterns of LTPA in adults may emerge from the dynamic interplay between psychological traits and built and social environments. We integrated existing theories and models as well as available empirical data (both from literature reviews), and expert opinions (based on a systematic expert assessment of an intermediary version of the model). The model explicitly presents intention as the proximal determinant of leisure-time physical activity, a relationship dynamically moderated by the built environment (access, quality, and available activities) - with the strength of the moderation varying as a function of the person's intention- and influenced both by the social environment (proximal network's and community's behavior) and the person's behavior. Our conceptual model is well supported by evidence and experts' opinions and will inform the design of our agent-based model, as well as data collection and analysis of future investigations on population patterns of leisure-time physical activity among adults.

Precision Lifetime Measurements in Molecular Hydrogen

NASA Astrophysics Data System (ADS)

Ray, Mark D.

1995-01-01

We have measured the lifetimes of three rovibrational levels--g ^3Sigma_sp {g}{+}(v = 1,N = 2), i ^3{rm II}_sp{g} {-}(v = 0,N = 1), and j ^3Delta_sp{g}{-}(v = 1,N = 3)--in the n = 3 complex of para H _2 with a precision of 2%. The lifetimes are 8.66 +/- 0.16 ns for i ^3{rm II}_sp{g }{-}(v = 0, N = 1), 6.05+/- 0.11 ns for g ^3Sigma_sp {g}{+}(v = 1,N = 2), and 12.77 +/- 0.30 ns for j ^3 Delta_sp{g}{-}(v = 1,N = 3). On the basis of the first two measurements, we suggest that a previously neglected decay channel should be included in theoretical treatments and may have played an important role in an earlier experiment. Our value for the lifetime of j ^3Delta _sp{g}{-}(v = 1,N = 3) agrees well with the earlier experiment; the best theoretical estimate lies almost 50% higher. The measurements are done in a molecular beam via laser photoionization. An intense beam of metastable (2p) c ^3{rm II}_sp {u}{-} levels is created by electron bombardment. Downstream, a specific rotational -vibrational level of an n = 3 electronic state is excited by a resonant laser. After a delay, the remaining population is photoionized by a second laser. By measuring the photoionization yield as a function of the delay between the exciting and photoionizing lasers, we are able to determine the lifetime of the excited level. With a few modifications to the experimental apparatus, we believe it is possible to measure lifetimes at the 0.5% level of precision. We also propose the use of muti-channel quantum defect theory to obtain accurate ab initio decay rates for some of the branches involved.

Simulating star clusters with the AMUSE software framework. I. Dependence of cluster lifetimes on model assumptions and cluster dissolution modes

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

Whitehead, Alfred J.; McMillan, Stephen L. W.; Vesperini, Enrico

2013-12-01

We perform a series of simulations of evolving star clusters using the Astrophysical Multipurpose Software Environment (AMUSE), a new community-based multi-physics simulation package, and compare our results to existing work. These simulations model a star cluster beginning with a King model distribution and a selection of power-law initial mass functions and contain a tidal cutoff. They are evolved using collisional stellar dynamics and include mass loss due to stellar evolution. After studying and understanding that the differences between AMUSE results and results from previous studies are understood, we explored the variation in cluster lifetimes due to the random realization noisemore » introduced by transforming a King model to specific initial conditions. This random realization noise can affect the lifetime of a simulated star cluster by up to 30%. Two modes of star cluster dissolution were identified: a mass evolution curve that contains a runaway cluster dissolution with a sudden loss of mass, and a dissolution mode that does not contain this feature. We refer to these dissolution modes as 'dynamical' and 'relaxation' dominated, respectively. For Salpeter-like initial mass functions, we determined the boundary between these two modes in terms of the dynamical and relaxation timescales.« less

Expected lifetime numbers and costs of fractures in postmenopausal women with and without osteoporosis in Germany: a discrete event simulation model

PubMed Central

2014-01-01

Background Osteoporotic fractures cause a large health burden and substantial costs. This study estimated the expected fracture numbers and costs for the remaining lifetime of postmenopausal women in Germany. Methods A discrete event simulation (DES) model which tracks changes in fracture risk due to osteoporosis, a previous fracture or institutionalization in a nursing home was developed. Expected lifetime fracture numbers and costs per capita were estimated for postmenopausal women (aged 50 and older) at average osteoporosis risk (AOR) and for those never suffering from osteoporosis. Direct and indirect costs were modeled. Deterministic univariate and probabilistic sensitivity analyses were conducted. Results The expected fracture numbers over the remaining lifetime of a 50 year old woman with AOR for each fracture type (% attributable to osteoporosis) were: hip 0.282 (57.9%), wrist 0.229 (18.2%), clinical vertebral 0.206 (39.2%), humerus 0.147 (43.5%), pelvis 0.105 (47.5%), and other femur 0.033 (52.1%). Expected discounted fracture lifetime costs (excess cost attributable to osteoporosis) per 50 year old woman with AOR amounted to €4,479 (€1,995). Most costs were accrued in the hospital €1,743 (€751) and long-term care sectors €1,210 (€620). Univariate sensitivity analysis resulted in percentage changes between -48.4% (if fracture rates decreased by 2% per year) and +83.5% (if fracture rates increased by 2% per year) compared to base case excess costs. Costs for women with osteoporosis were about 3.3 times of those never getting osteoporosis (€7,463 vs. €2,247), and were markedly increased for women with a previous fracture. Conclusion The results of this study indicate that osteoporosis causes a substantial share of fracture costs in postmenopausal women, which strongly increase with age and previous fractures. PMID:24981316

Expected lifetime numbers and costs of fractures in postmenopausal women with and without osteoporosis in Germany: a discrete event simulation model.

PubMed

Bleibler, Florian; Rapp, Kilian; Jaensch, Andrea; Becker, Clemens; König, Hans-Helmut

2014-06-30

Osteoporotic fractures cause a large health burden and substantial costs. This study estimated the expected fracture numbers and costs for the remaining lifetime of postmenopausal women in Germany. A discrete event simulation (DES) model which tracks changes in fracture risk due to osteoporosis, a previous fracture or institutionalization in a nursing home was developed. Expected lifetime fracture numbers and costs per capita were estimated for postmenopausal women (aged 50 and older) at average osteoporosis risk (AOR) and for those never suffering from osteoporosis. Direct and indirect costs were modeled. Deterministic univariate and probabilistic sensitivity analyses were conducted. The expected fracture numbers over the remaining lifetime of a 50 year old woman with AOR for each fracture type (% attributable to osteoporosis) were: hip 0.282 (57.9%), wrist 0.229 (18.2%), clinical vertebral 0.206 (39.2%), humerus 0.147 (43.5%), pelvis 0.105 (47.5%), and other femur 0.033 (52.1%). Expected discounted fracture lifetime costs (excess cost attributable to osteoporosis) per 50 year old woman with AOR amounted to € 4,479 (€ 1,995). Most costs were accrued in the hospital € 1,743 (€ 751) and long-term care sectors € 1,210 (€ 620). Univariate sensitivity analysis resulted in percentage changes between -48.4% (if fracture rates decreased by 2% per year) and +83.5% (if fracture rates increased by 2% per year) compared to base case excess costs. Costs for women with osteoporosis were about 3.3 times of those never getting osteoporosis (€ 7,463 vs. € 2,247), and were markedly increased for women with a previous fracture. The results of this study indicate that osteoporosis causes a substantial share of fracture costs in postmenopausal women, which strongly increase with age and previous fractures.

Förster resonance energy transfer (FRET)-based picosecond lifetime reference for instrument response evaluation

NASA Astrophysics Data System (ADS)

Luchowski, R.; Kapusta, P.; Szabelski, M.; Sarkar, P.; Borejdo, J.; Gryczynski, Z.; Gryczynski, I.

2009-09-01

Förster resonance energy transfer (FRET) can be utilized to achieve ultrashort fluorescence responses in time-domain fluorometry. In a poly(vinyl) alcohol matrix, the presence of 60 mM Rhodamine 800 acceptor shortens the fluorescence lifetime of a pyridine 1 donor to about 20 ps. Such a fast fluorescence response is very similar to the instrument response function (IRF) obtained using scattered excitation light. A solid fluorescent sample (e.g a film) with picosecond lifetime is ideal for IRF measurements and particularly useful for time-resolved microscopy. Avalanche photodiode detectors, commonly used in this field, feature color- dependent-timing responses. We demonstrate that recording the fluorescence decay of the proposed FRET-based reference sample yields a better IRF approximation than the conventional light-scattering method and therefore avoids systematic errors in decay curve analysis.

Determination of carrier lifetime and mobility in colloidal quantum dot films via impedance spectroscopy

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

Rath, Arup K.; Lasanta, Tania; Bernechea, Maria

2014-02-10

Impedance Spectroscopy (IS) proves to be a powerful tool for the determination of carrier lifetime and majority carrier mobility in colloidal quantum dot films. We employ IS to determine the carrier lifetime in PbS quantum dot Schottky solar cells with Al and we verify the validity of the technique via transient photovoltage. We also present a simple approach based on an RC model that allows the determination of carrier mobility in PbS quantum dot films and we corroborate the results via comparison with space charge limited measurements. In summary, we demonstrate the potential of IS to characterize key-to-photovoltaics optoelectronic properties,more » carrier lifetime, and mobility, in a facile way.« less

Assessing long-run economic benefits attributed to an IVF-conceived singleton based on projected lifetime net tax contributions in the UK.

PubMed

Connolly, M; Gallo, F; Hoorens, S; Ledger, W

2009-03-01

Over the past decade, demand for fertility treatments has increased as a result of delaying time to first pregnancy and growing awareness and acceptance of available treatment options. Despite increasing demand, health authorities often view infertility as a low health priority and consequently limit access to treatments by rationing and limiting funds. To assess the long-term economic benefits attributed to in vitro fertilization (IVF)-conceived children, we developed a health investment model to evaluate whether state-funded IVF programmes in the UK represent sound fiscal policies. Based on the average investment cost to conceive an IVF singleton, we describe the present value of net taxes derived from gross taxes paid minus direct government transfers received (e.g. education, health, pension) over the lifetime of the child. To establish the present value of investing in IVF, we have discounted all costs from benefits (i.e. lifetime taxes paid) using UK Treasury department rates based on a singleton delivery with similar characteristics for education, earnings, health and life expectancy to a naturally conceived child. The lifetime discounted value of net taxes from an IVF-conceived child with mother aged 35 is pound 109,939 compared with pound 122,127 for a naturally conceived child. The lifetime undiscounted net tax contribution for the IVF-conceived child and naturally conceived child are pound 603,000 and pound 616,000, respectively. An investment of pound 12,931 to achieve an IVF singleton is actually worth 8.5-times this amount to the UK Treasury in discounted future tax revenue. The analysis underscores that costs to the health sector are actually investments when a broader government perspective is considered over a longer period of time.

Lifetime earnings for physicians across specialties.

PubMed

Leigh, J Paul; Tancredi, Daniel; Jerant, Anthony; Romano, Patrick S; Kravitz, Richard L

2012-12-01

Earlier studies estimated annual income differences across specialties, but lifetime income may be more relevant given physicians' long-term commitments to specialties. Annual income and work hours data were collected from 6381 physicians in the nationally representative 2004-2005 Community Tracking Study. Data regarding years of residency were collected from AMA FREIDA. Present value models were constructed assuming 3% discount rates. Estimates were adjusted for demographic and market covariates. Sensitivity analyses included 4 alternative models involving work hours, retirement, exogenous variables, and 1% discount rate. Estimates were generated for 4 broad specialty categories (Primary Care, Surgery, Internal Medicine and Pediatric Subspecialties, and Other), and for 41 specific specialties. The estimates of lifetime earnings for the broad categories of Surgery, Internal Medicine and Pediatric Subspecialties, and Other specialties were $1,587,722, $1,099,655, and $761,402 more than for Primary Care. For the 41 specific specialties, the top 3 (with family medicine as reference) were neurological surgery ($2,880,601), medical oncology ($2,772,665), and radiation oncology ($2,659,657). The estimates from models with varying rates of retirement and including only exogenous variables were similar to those in the preferred model. The 1% discount model generated estimates that were roughly 150% larger than the 3% model. There was considerable variation in the lifetime earnings across physician specialties. After accounting for varying residency years and discounting future earnings, primary care specialties earned roughly $1-3 million less than other specialties. Earnings' differences across specialties may undermine health reform efforts to control costs and ensure adequate numbers of primary care physicians.

Occupational Stress: A Comprehensive Review of the Top 50 Annual and Lifetime Cited Articles.

PubMed

Nowrouzi, Behdin; Nguyen, Christine; Casole, Jennifer; Nowrouzi-Kia, Behnam

2017-05-01

This study determined the impact and influence of published articles on the field of occupational stress. A transdisciplinary approach was used to identify the 50 work-related stress articles with the most lifetime citations and the 50 work-related stress articles with the highest annual citation rates. Studies were categorized based on their primary focus: (a) etiology, (b) predictor of outcome for which occupational stress is the outcome or predictor of outcome for which occupational stress is an independent variable, (c) management/intervention, (d) theory/model/framework, or (e) methodologies. The majority of studies with the highest number of lifetime citations as well as the highest annual citation rates used stress as a predictor or outcome of another factor. The proportion of studies that were categorized by etiology, intervention/management, theory/model/framework, or methodologies was relatively low for both lifetime and annual citations.

Population pharmacokinetic-pharmacodynamic modeling and model-based prediction of docetaxel-induced neutropenia in Japanese patients with non-small cell lung cancer.

PubMed

Fukae, Masato; Shiraishi, Yoshimasa; Hirota, Takeshi; Sasaki, Yuka; Yamahashi, Mika; Takayama, Koichi; Nakanishi, Yoichi; Ieiri, Ichiro

2016-11-01

Docetaxel is used to treat many cancers, and neutropenia is the dose-limiting factor for its clinical use. A population pharmacokinetic-pharmacodynamic (PK-PD) model was introduced to predict the development of docetaxel-induced neutropenia in Japanese patients with non-small cell lung cancer (NSCLC). Forty-seven advanced or recurrent Japanese patients with NSCLC were enrolled. Patients received 50 or 60 mg/m 2 docetaxel as monotherapy, and blood samples for a PK analysis were collected up to 24 h after its infusion. Laboratory tests including absolute neutrophil count data and demographic information were used in population PK-PD modeling. The model was built by NONMEM 7.2 with a first-order conditional estimation using an interaction method. Based on the final model, a Monte Carlo simulation was performed to assess the impact of covariates on and the predictability of neutropenia. A three-compartment model was employed to describe PK data, and the PK model adequately described the docetaxel concentrations observed. Serum albumin (ALB) was detected as a covariate of clearance (CL): CL (L/h) = 32.5 × (ALB/3.6) 0.965  × (WGHT/70) 3/4 . In population PK-PD modeling, a modified semi-mechanistic myelosuppression model was applied, and characterization of the time course of neutrophil counts was adequate. The covariate selection indicated that α1-acid glycoprotein (AAG) was a predictor of neutropenia. The model-based simulation also showed that ALB and AAG negatively correlated with the development of neutropenia and that the time course of neutrophil counts was predictable. The developed model may facilitate the prediction and care of docetaxel-induced neutropenia.

Results and Systematic Studies of the UCN Lifetime Experiment at NIST

NASA Astrophysics Data System (ADS)

Huffer, Craig Reeves

The neutron beta-decay lifetime is important in understanding weak interactions in the framework of the Standard Model, and it is an input to nuclear astrophysics and Big Bang Nucleosynthesis. Current measurements of the neutron beta-decay lifetime disagree, which has motivated additional experiments that are sensitive to different sets of systematic effects. An effort continues at the NIST Center for Neutron Research (NCNR) to improve the statistical and systematic limitations of an experiment to measure the neutron beta-decay lifetime using magnetically trapped UCN. In the experiment, a monoenergetic 0:89 nm cold neutron is incident on a superfluid 4He target within the minimum field region of an Ioffe type magnetic trap. Some of the neutrons are subsequently downscattered by single phonons in the helium to low energies (≈ 200 neV), and those in the appropriate spin state become trapped. The inverse process, upscattering of UCN, is suppressed by the low phonon density in the < 300 mK helium. When the neutron decays, the energetic electron creates EUV scintillation light, which is down-converted and transported out of the cell to PMTs operated at room temperature. With this method, the decay of the UCN population can be monitored in situ. The apparatus, analysis, data, and systematics will be discussed. After accounting for the systematic effects the measured lifetime disagrees with the current PDG mean neutron beta-decay lifetime by about 9 of our standard deviations, which is a strong indication of unaccounted for systematic effects. Additional 3He contamination will be shown to be the most likely candidate for the additional systematic shift, which motivated the commissioning and initial operation of a heat flush purifier for purifying additional 4He. This work ends with a description of the 4He purifier and its performance.

Indacaterol/glycopyrronium is cost-effective compared to salmeterol/fluticasone in COPD: FLAME-based modelling in a Swedish population.

PubMed

Bjermer, Leif; van Boven, Job F M; Costa-Scharplatz, Madlaina; Keininger, Dorothy L; Gutzwiller, Florian S; Lisspers, Karin; Mahon, Ronan; Olsson, Petter; Roche, Nicolas

2017-12-11

This study assessed the cost-effectiveness of indacaterol/glycopyrronium (IND/GLY) versus salmeterol/fluticasone (SFC) in chronic obstructive pulmonary disease (COPD) patients with moderate to very severe airflow limitation and ≥1 exacerbation in the preceding year. A previously published and validated patient-level simulation model was adapted using clinical data from the FLAME trial and real-world cost data from the ARCTIC study. Costs (total monetary costs comprising drug, maintenance, exacerbation, and pneumonia costs) and health outcomes (life-years (LYs), quality-adjusted life-years (QALYs)) were projected over various time horizons (1, 5, 10 years, and lifetime) from the Swedish payer's perspective and were discounted at 3% annually. Uncertainty in model input values was studied through one-way and probabilistic sensitivity analyses. Subgroup analyses were also performed. IND/GLY was associated with lower costs and better outcomes compared with SFC over all the analysed time horizons. Use of IND/GLY resulted in additional 0.192 LYs and 0.134 QALYs with cost savings of €1211 compared with SFC over lifetime. The net monetary benefit (NMB) was estimated to be €8560 based on a willingness-to-pay threshold of €55,000/QALY. The NMB was higher in the following subgroups: severe (GOLD 3), high risk and more symptoms (GOLD D), females, and current smokers. IND/GLY is a cost-effective treatment compared with SFC in COPD patients with mMRC dyspnea grade ≥ 2, moderate to very severe airflow limitation, and ≥1 exacerbation in the preceding year.

Ultrashort fluorescence lifetimes of hydrogen-bonded base pairs of guanosine and cytidine in solution.

PubMed

Schwalb, Nina K; Michalak, Thomas; Temps, Friedrich

2009-12-24

The optically excited electronic states of hydrogen-bonded homo- and heterodimers of guanosine (G) and deoxycytidine (C) were investigated by femtosecond fluorescence up-conversion spectroscopy. The base pairs were prepared in CHCl(3) solution by employing tert-butyldimethylsilyl (TBDMS) groups at the OH positions of the ribose (G) or deoxyribose (C) moieties to enhance the solubilities of the nucleosides in organic solvents. The H-bonded complexes that were obtained were characterized by FTIR spectroscopy. Fluorescence lifetime measurements were performed following electronic excitation at a series of UV wavelengths from lambda(pump) = 294 nm, close to the electronic origins of the bases, to lambda(pump) = 262 nm, where significant excess vibronic energy is deposited in the molecules, at nucleoside concentrations of c(0) = 0.1 and 1.0 mM. The experimental results revealed the existence of an ultrafast deactivation pathway for the optically prepared electronically excited state(s) of the G.C Watson-Crick base pair, which was found to have a lifetime of tau(GC) = 0.30(3) ps (with 2sigma error limits) irrespective of the pump wavelength. A similar short decay time, tau(GG) = 0.32(2) ps, was observed for the respective excited G.G homodimer. In contrast, the excited G monomer displayed a significantly longer-lived and wavelength-dependent deactivation, requiring three time constants, between 0.43(6) ps < or = tau(G,1) < or = 1.2(1) ps, 4.2(8) ps < or = tau(G,2) < or = 8(1) ps, and tau(G,3) = 195(32) ps. Self-complexation of C, on the other hand, led to a longer-lived excited state with a lifetime estimated between 1 ps < or = tau(CC) < or = 10 ps, compared to the dominant initial subpicosecond decay time of the C monomer of tau(C,1) = 0.80(4) ps.

Estimating and modelling cure in population-based cancer studies within the framework of flexible parametric survival models

PubMed Central

2011-01-01

Background When the mortality among a cancer patient group returns to the same level as in the general population, that is, the patients no longer experience excess mortality, the patients still alive are considered "statistically cured". Cure models can be used to estimate the cure proportion as well as the survival function of the "uncured". One limitation of parametric cure models is that the functional form of the survival of the "uncured" has to be specified. It can sometimes be hard to find a survival function flexible enough to fit the observed data, for example, when there is high excess hazard within a few months from diagnosis, which is common among older age groups. This has led to the exclusion of older age groups in population-based cancer studies using cure models. Methods Here we have extended the flexible parametric survival model to incorporate cure as a special case to estimate the cure proportion and the survival of the "uncured". Flexible parametric survival models use splines to model the underlying hazard function, and therefore no parametric distribution has to be specified. Results We have compared the fit from standard cure models to our flexible cure model, using data on colon cancer patients in Finland. This new method gives similar results to a standard cure model, when it is reliable, and better fit when the standard cure model gives biased estimates. Conclusions Cure models within the framework of flexible parametric models enables cure modelling when standard models give biased estimates. These flexible cure models enable inclusion of older age groups and can give stage-specific estimates, which is not always possible from parametric cure models. PMID:21696598

Changes in the lifetime prevalence of suicidal feelings and thoughts among Norwegian doctors from 2000 to 2010: a longitudinal study based on national samples

PubMed Central

2013-01-01

Background Thinking about suicide is an indicator of suicide risk. Suicide rates are higher among doctors than in the population. The main aims of this study are to describe the changes in the lifetime prevalence of suicidal feelings from 2000 to 2010 and the possible predictors of serious suicidal thoughts in 2010 among Norwegian doctors. Differences in lifetime prevalence of suicidal feelings between Norwegian doctors in 2010 and German doctors in 2006 will be also described. Methods Longitudinal and cross-sectional study based on questionnaire data from 2000 and 2010, including approximately 1,600 Norwegian doctors. In Germany, cross-sectional study based on questionnaire data from 2006 among a sample of 3,295 doctors. The main outcome measures were the lifetime prevalence of suicidal feelings (felt life was not worth living, wished own death, had thoughts of taking own life). Results The prevalences in 2000 and 2010 of ever had feelings of life not worth living were 48 (44 to 52) % and 45 (41 to 49) %, of ever wished own death 27 (23 to 30) % and 23 (20 to 26) %, and of ever had thoughts of taking own life 29 (16 to 33) % and 24 (21 to 27) %. Paired t-tests among those who responded both in 2000 and 2010 show significant reductions for felt life not worth living (t = −3.4; p = 0.001), wished own death (t = −3.1; p = 0.002) and had thoughts of taking own life (t = −3.5; p < 0.0001). In 2010, significant predictors of serious suicidal thoughts in a multivariate model were low subjective well-being (OR 0.68; 95% CI 0.52-0.90), poor or average self-rated health (2.36; 1.25-4.45) and high psychosocial work stress (1.92; 1.06-3.46), controlled for age, gender, speciality and job satisfaction. Norwegian doctors in 2010 compared with their German counterparts in 2006 reported quite similar prevalences of suicidal feelings. Conclusions Suicidal feelings among Norwegian doctors decreased from 2000 to 2010. Individual and work-related factors may to certain explain

Changes in the lifetime prevalence of suicidal feelings and thoughts among Norwegian doctors from 2000 to 2010: a longitudinal study based on national samples.

PubMed

Rosta, Judith; Aasland, Olaf G

2013-11-28

Thinking about suicide is an indicator of suicide risk. Suicide rates are higher among doctors than in the population. The main aims of this study are to describe the changes in the lifetime prevalence of suicidal feelings from 2000 to 2010 and the possible predictors of serious suicidal thoughts in 2010 among Norwegian doctors. Differences in lifetime prevalence of suicidal feelings between Norwegian doctors in 2010 and German doctors in 2006 will be also described. Longitudinal and cross-sectional study based on questionnaire data from 2000 and 2010, including approximately 1,600 Norwegian doctors. In Germany, cross-sectional study based on questionnaire data from 2006 among a sample of 3,295 doctors. The main outcome measures were the lifetime prevalence of suicidal feelings (felt life was not worth living, wished own death, had thoughts of taking own life). The prevalences in 2000 and 2010 of ever had feelings of life not worth living were 48 (44 to 52) % and 45 (41 to 49) %, of ever wished own death 27 (23 to 30) % and 23 (20 to 26) %, and of ever had thoughts of taking own life 29 (16 to 33) % and 24 (21 to 27) %. Paired t-tests among those who responded both in 2000 and 2010 show significant reductions for felt life not worth living (t = -3.4; p = 0.001), wished own death (t = -3.1; p = 0.002) and had thoughts of taking own life (t = -3.5; p < 0.0001). In 2010, significant predictors of serious suicidal thoughts in a multivariate model were low subjective well-being (OR 0.68; 95% CI 0.52-0.90), poor or average self-rated health (2.36; 1.25-4.45) and high psychosocial work stress (1.92; 1.06-3.46), controlled for age, gender, speciality and job satisfaction. Norwegian doctors in 2010 compared with their German counterparts in 2006 reported quite similar prevalences of suicidal feelings. Suicidal feelings among Norwegian doctors decreased from 2000 to 2010. Individual and work-related factors may to certain explain these findings. Compared with other

Socioeconomic status during lifetime and cognitive impairment no-dementia in late life: the population-based aging in the Chianti Area (InCHIANTI) Study.

PubMed

Marengoni, Alessandra; Fratiglioni, Laura; Bandinelli, Stefania; Ferrucci, Luigi

2011-01-01

Thousand and twelve dementia-free elderly (60–98 years old) enrolled in the InChianti Study (Italy) were evaluated at baseline (1998–2000) and at 3-year follow-up (2001–2003) with the aim of analyzing the association of lifetime socioeconomic status (SES) with prevalent and incident cognitive impairment no-dementia (CIND). SES was defined from information on formal education, longest held occupation, and financial conditions through life. CIND was defined as age-adjusted Mini-Mental State Examination score one standard deviation below the baseline mean score of participants without dementia. Logistic regression and Cox proportional-hazards models were used to estimate the association of SES with CIND. Demographics,occupation characteristics (i.e., job stress and physical demand), cardiovascular diseases, diabetes, apolipoprotein E (APOE)genotype, smoking, alcohol consumption, depressive symptoms, and C-reactive protein were considered potential confounders.Prevalence of CIND was 17.7%. In the fully adjusted model, low education (OR = 2.1; 95% confidence intervals, CI = 1.4 to 3.2)was associated with prevalent CIND. Incidence rate of CIND was 66.0 per 1000 person-years. Low education (HR = 1.7; 95% CI = 1.04 to 2.6) and manual occupation (HR = 1.9; 95% CI = 1.0 to 3.6) were associated with incident CIND. Among covariates,high job-related physical demand was associated with both prevalent and incident CIND (OR = 1.6; 95% CI = 1.1 to 2.4 and HR= 1.5; 95% CI = 1.0 to 2.3). After stratification for education, manual occupation was still associated with CIND among participants with high education (HR = 2.2; 95% CI = 1.2 to 4.3 versus HR= 1.4; 95% CI = 0.2 to 10.4 among those with low education). Proxy markers of lifetime SES (low education, manual occupation and high physical demand) are cross-sectional correlates of CIND and predict incident CIND over a three-year follow-up.

Insight into carrier lifetime impact on band-modulation devices

NASA Astrophysics Data System (ADS)

Parihar, Mukta Singh; Lee, Kyung Hwa; Park, Hyung Jin; Lacord, Joris; Martinie, Sébastien; Barbé, Jean-Charles; Xu, Yue; El Dirani, Hassan; Taur, Yuan; Cristoloveanu, Sorin; Bawedin, Maryline

2018-05-01

A systematic study to model and characterize the band-modulation Z2-FET device is developed bringing light to the relevance of the carrier lifetime influence. This work provides guidelines to optimize the Z2-FETs for sharp switching, ESD protection, and 1T-DRAM applications. Lower carrier lifetime in the Z2-FET helps in attaining the sharp switch. We provide new insights into the correlation between generation/recombination, diffusion, electrostatic barriers and carrier lifetime.

Fluorescence lifetime imaging of endogenous molecules in live mouse cancer models (Conference Presentation)

NASA Astrophysics Data System (ADS)

Svindrych, Zdenek; Wang, Tianxiong; Hu, Song; Periasamy, Ammasi

2017-02-01

NADH and FAD are important endogenous fluorescent coenzymes participating in key enzymatic reactions of cellular metabolism. While fluorescence intensities of NADH and FAD have been used to determine the redox state of cells and tissues, this simple approach breaks down in the case of deep-tissue intravital imaging due to depth- and wavelength-dependent light absorption and scattering. To circumvent this limitation, our research focuses on fluorescence lifetimes of two-photon excited NADH and FAD emission to study the metabolic state of live tissues. In our custom-built scanning microscope we combine tunable femtosecond Ti:sapphire laser (operating at 740 nm for NADH excitation and 890 nm for FAD excitation), two GaAsP hybrid detectors for registering individual fluorescence photons and two Becker and Hickl time correlator boards for high precision lifetime measurements. Together with our rigorous FLIM analysis approach (including image segmentation, multi-exponential decay fitting and detailed statistical analysis) we are able to detect metabolic changes in cancer xenografts (human pancreatic cancer MPanc96 cells injected subcutaneously into the ear of an immunodeficient nude mouse), relative to surrounding healthy tissue. Advantageously, with the same instrumentation we can also take high-resolution and high-contrast images of second harmonic signal (SHG) originating from collagen fibers of both the healthy skin and the growing tumor. The combination of metabolic measurements (NADH and FAD lifetime) and morphological information (collagen SHG) allows us to follow the tumor growth in live mouse model and the changes in tumor microenvironment.

Heritability of lifetime ecstasy use.

PubMed

Verweij, Karin J H; Treur, Jorien L; Vreeker, Annabel; Brunt, Tibor M; Willemsen, Gonneke; Boomsma, Dorret I; Vink, Jacqueline M

2017-09-01

Ecstasy is a widely used psychoactive drug that users often take because they experience positive effects such as increased euphoria, sociability, elevated mood, and heightened sensations. Ecstasy use is not harmless and several immediate and long term side effects have been identified. Lifetime ecstasy use is likely to be partly influenced by genetic factors, but no twin study has determined the heritability. Here, we apply a classical twin design to a large sample of twins and siblings to estimate the heritability of lifetime ecstasy use. The sample comprised 8500 twins and siblings aged between 18 and 45 years from 5402 families registered at the Netherlands Twin Registry. In 2013-2014 participants filled out a questionnaire including a question whether they had ever used ecstasy. We used the classical twin design to partition the individual differences in liability to ecstasy use into that due to genetic, shared environmental, and residual components. Overall, 10.4% of the sample had used ecstasy during their lifetime, with a somewhat higher prevalence in males than females. Twin modelling indicated that individual differences in liability to lifetime ecstasy use are for 74% due to genetic differences between individuals, whereas shared environmental and residual factors explain a small proportion of its liability (5% and 21%, respectively). Although heritability estimates appeared to be higher for females than males, this difference was not significant. Lifetime ecstasy use is a highly heritable trait, which indicates that some people are genetically more vulnerable to start using ecstasy than others. Copyright © 2017. Published by Elsevier B.V.

Time-Domain Microfluidic Fluorescence Lifetime Flow Cytometry for High-Throughput Förster Resonance Energy Transfer Screening

PubMed Central

Nedbal, Jakub; Visitkul, Viput; Ortiz-Zapater, Elena; Weitsman, Gregory; Chana, Prabhjoat; Matthews, Daniel R; Ng, Tony; Ameer-Beg, Simon M

2015-01-01

Sensing ion or ligand concentrations, physico-chemical conditions, and molecular dimerization or conformation change is possible by assays involving fluorescent lifetime imaging. The inherent low throughput of imaging impedes rigorous statistical data analysis on large cell numbers. We address this limitation by developing a fluorescence lifetime-measuring flow cytometer for fast fluorescence lifetime quantification in living or fixed cell populations. The instrument combines a time-correlated single photon counting epifluorescent microscope with microfluidics cell-handling system. The associated computer software performs burst integrated fluorescence lifetime analysis to assign fluorescence lifetime, intensity, and burst duration to each passing cell. The maximum safe throughput of the instrument reaches 3,000 particles per minute. Living cells expressing spectroscopic rulers of varying peptide lengths were distinguishable by Förster resonant energy transfer measured by donor fluorescence lifetime. An epidermal growth factor (EGF)-stimulation assay demonstrated the technique's capacity to selectively quantify EGF receptor phosphorylation in cells, which was impossible by measuring sensitized emission on a standard flow cytometer. Dual-color fluorescence lifetime detection and cell-specific chemical environment sensing were exemplified using di-4-ANEPPDHQ, a lipophilic environmentally sensitive dye that exhibits changes in its fluorescence lifetime as a function of membrane lipid order. To our knowledge, this instrument opens new applications in flow cytometry which were unavailable due to technological limitations of previously reported fluorescent lifetime flow cytometers. The presented technique is sensitive to lifetimes of most popular fluorophores in the 0.5–5 ns range including fluorescent proteins and is capable of detecting multi-exponential fluorescence lifetime decays. This instrument vastly enhances the throughput of experiments involving

3D printed miniaturized spectral system for tissue fluorescence lifetime measurements

NASA Astrophysics Data System (ADS)

Zou, Luwei; Mahmoud, Mohamad; Fahs, Mehdi; Liu, Rui; Lo, Joe F.

2016-04-01

Various types of collagens, e.g. type I and III, represent the main load-bearing components in biological tissues. Their composition changes during processes like wound healing and fibrosis. Collagens exhibit autofluorescence when excited by ultra-violet light, distinguishable by their unique fluorescent lifetimes across a range of emission wavelengths. Therefore, we designed a miniaturized spectral-lifetime detection system for collagens as a non-invasive probe for monitoring tissue in wound healing and scarring applications. A sine modulated LED illumination was applied to enable frequency domain (FD) fluorescence lifetime measurements under different wavelengths bands, separated via a series of longpass dichroics at 387nm, 409nm and 435nm. To achieve the minute scale of optomechanics, we employed a stereolithography based 3D printer with <50 μm resolution to create a custom designed optical mount in a hand-held form factor. We examined the characteristics of the 3D printed optical system with finite element modeling to simulate the effect of thermal (LED) and mechanical (handling) strain on the optical system. Using this device, the phase shift and demodulation of collagen types were measured, where the separate spectral bands enhanced the differentiation of their lifetimes.

A Lifetime Maximization Relay Selection Scheme in Wireless Body Area Networks.

PubMed

Zhang, Yu; Zhang, Bing; Zhang, Shi

2017-06-02

Network Lifetime is one of the most important metrics in Wireless Body Area Networks (WBANs). In this paper, a relay selection scheme is proposed under the topology constrains specified in the IEEE 802.15.6 standard to maximize the lifetime of WBANs through formulating and solving an optimization problem where relay selection of each node acts as optimization variable. Considering the diversity of the sensor nodes in WBANs, the optimization problem takes not only energy consumption rate but also energy difference among sensor nodes into account to improve the network lifetime performance. Since it is Non-deterministic Polynomial-hard (NP-hard) and intractable, a heuristic solution is then designed to rapidly address the optimization. The simulation results indicate that the proposed relay selection scheme has better performance in network lifetime compared with existing algorithms and that the heuristic solution has low time complexity with only a negligible performance degradation gap from optimal value. Furthermore, we also conduct simulations based on a general WBAN model to comprehensively illustrate the advantages of the proposed algorithm. At the end of the evaluation, we validate the feasibility of our proposed scheme via an implementation discussion.

Chasing quicksilver: modeling the atmospheric lifetime of Hg(0)(g) in the marine boundary layer at various latitudes.

PubMed

Hedgecock, Ian M; Pirrone, Nicola

2004-01-01

The lifetime of elemental mercury in the marine boundary layer(MBL) has been studied using AMCOTS (Atmospheric Mercury Chemistry Over The Sea), a box model of MBL photochemistry including aerosols and detailed mercury chemistry. Recently measured Hg(0)(g) oxidation reactions have been included, and the studies were performed as a function of latitude, time of year, boundary layer liquid water content (LWC) and cloud optical depth. The results show that Hg has the shortest lifetime when air temperatures are low and sunlight and deliquescent aerosol particles are plentiful. Thus the modeled lifetime for clear-sky conditions is actually shorter at mid-latitudes and high latitudes than near the equator, and for a given latitude and time of year, cooler temperatures enhance the rate of Hg oxidation. Under typical summer conditions (for a given latitude) of temperature and cloudiness, the lifetime (tau) of Hg(0)(g) in the MBL is calculated to be around 10 days at all latitudes between the equator and 60 degrees N. This is much shorter than the generally accepted atmospheric residence time for Hg(0)(g) of a year or more. Given the relatively stable background concentrations of Hg(0)(g) which have been measured, continual replenishment of Hg(0)(g) must take place, suggesting a "multihop" mechanism for the distribution of Hg, rather than solely aeolian transport with little or no chemical transformation between source and receptor. Inclusion of an empirical Hg(0)(g) emission factor related to insolation was used to stabilize the Hg(0)(g) concentration in the model, and the emission rates necessarily agree well with estimated emission fluxes for the open ocean.

Endurance degradation and lifetime model of p-channel floating gate flash memory device with 2T structure

NASA Astrophysics Data System (ADS)

Wei, Jiaxing; Liu, Siyang; Liu, Xiaoqiang; Sun, Weifeng; Liu, Yuwei; Liu, Xiaohong; Hou, Bo

2017-08-01

The endurance degradation mechanisms of p-channel floating gate flash memory device with two-transistor (2T) structure are investigated in detail in this work. With the help of charge pumping (CP) measurements and Sentaurus TCAD simulations, the damages in the drain overlap region along the tunnel oxide interface caused by band-to-band (BTB) tunneling programming and the damages in the channel region resulted from Fowler-Nordheim (FN) tunneling erasure are verified respectively. Furthermore, the lifetime model of endurance characteristic is extracted, which can extrapolate the endurance degradation tendency and predict the lifetime of the device.

Impact of different policies on unhealthy dietary behaviors in an urban adult population: an agent-based simulation model.

PubMed

Zhang, Donglan; Giabbanelli, Philippe J; Arah, Onyebuchi A; Zimmerman, Frederick J

2014-07-01

Unhealthy eating is a complex-system problem. We used agent-based modeling to examine the effects of different policies on unhealthy eating behaviors. We developed an agent-based simulation model to represent a synthetic population of adults in Pasadena, CA, and how they make dietary decisions. Data from the 2007 Food Attitudes and Behaviors Survey and other empirical studies were used to calibrate the parameters of the model. Simulations were performed to contrast the potential effects of various policies on the evolution of dietary decisions. Our model showed that a 20% increase in taxes on fast foods would lower the probability of fast-food consumption by 3 percentage points, whereas improving the visibility of positive social norms by 10%, either through community-based or mass-media campaigns, could improve the consumption of fruits and vegetables by 7 percentage points and lower fast-food consumption by 6 percentage points. Zoning policies had no significant impact. Interventions emphasizing healthy eating norms may be more effective than directly targeting food prices or regulating local food outlets. Agent-based modeling may be a useful tool for testing the population-level effects of various policies within complex systems.

Impact of Different Policies on Unhealthy Dietary Behaviors in an Urban Adult Population: An Agent-Based Simulation Model

PubMed Central

Giabbanelli, Philippe J.; Arah, Onyebuchi A.; Zimmerman, Frederick J.

2014-01-01

Objectives. Unhealthy eating is a complex-system problem. We used agent-based modeling to examine the effects of different policies on unhealthy eating behaviors. Methods. We developed an agent-based simulation model to represent a synthetic population of adults in Pasadena, CA, and how they make dietary decisions. Data from the 2007 Food Attitudes and Behaviors Survey and other empirical studies were used to calibrate the parameters of the model. Simulations were performed to contrast the potential effects of various policies on the evolution of dietary decisions. Results. Our model showed that a 20% increase in taxes on fast foods would lower the probability of fast-food consumption by 3 percentage points, whereas improving the visibility of positive social norms by 10%, either through community-based or mass-media campaigns, could improve the consumption of fruits and vegetables by 7 percentage points and lower fast-food consumption by 6 percentage points. Zoning policies had no significant impact. Conclusions. Interventions emphasizing healthy eating norms may be more effective than directly targeting food prices or regulating local food outlets. Agent-based modeling may be a useful tool for testing the population-level effects of various policies within complex systems. PMID:24832414

Application of phasor plot and autofluorescence correction for study of heterogeneous cell population

PubMed Central

Szmacinski, Henryk; Toshchakov, Vladimir; Lakowicz, Joseph R.

2014-01-01

Abstract. Protein-protein interactions in cells are often studied using fluorescence resonance energy transfer (FRET) phenomenon by fluorescence lifetime imaging microscopy (FLIM). Here, we demonstrate approaches to the quantitative analysis of FRET in cell population in a case complicated by a highly heterogeneous donor expression, multiexponential donor lifetime, large contribution of cell autofluorescence, and significant presence of unquenched donor molecules that do not interact with the acceptor due to low affinity of donor-acceptor binding. We applied a multifrequency phasor plot to visualize FRET FLIM data, developed a method for lifetime background correction, and performed a detailed time-resolved analysis using a biexponential model. These approaches were applied to study the interaction between the Toll Interleukin-1 receptor (TIR) domain of Toll-like receptor 4 (TLR4) and the decoy peptide 4BB. TLR4 was fused to Cerulean fluorescent protein (Cer) and 4BB peptide was labeled with Bodipy TMRX (BTX). Phasor displays for multifrequency FLIM data are presented. The analytical procedure for lifetime background correction is described and the effect of correction on FLIM data is demonstrated. The absolute FRET efficiency was determined based on the phasor plot display and multifrequency FLIM data analysis. The binding affinity between TLR4-Cer (donor) and decoy peptide 4BB-BTX (acceptor) was estimated in a heterogeneous HeLa cell population. PMID:24770662

Physical comorbidities in men with mood and anxiety disorders: a population-based study

PubMed Central

2013-01-01

Background The mind-body nexus has been a topic of growing interest. Further data are however required to understand the specific relationship between mood and anxiety disorders and individual physical health conditions, and to verify whether these psychiatric disorders are linked to overall medical burden. Methods This study examined data collected from 942 men, 20 to 97 years old, participating in the Geelong Osteoporosis Study. A lifetime history of mood and anxiety disorders was identified using the Structured Clinical Interview for DSM-IV-TR Research Version, Non-patient edition (SCID-I/NP). The presence of medical conditions (lifetime) was self-reported and confirmed by medical records, medication use or clinical data. Anthropometric measurements and socioeconomic status (SES) were determined and information on medication use and lifestyle was obtained via questionnaire. Logistic regression models were used to test the associations. Results After adjustment for age, socioeconomic status, and health risk factors (body mass index, physical activity and smoking), mood disorders were associated with gastro oesophageal reflux disease (GORD), recurrent headaches, blackouts and/or epilepsy, liver disorders and pulmonary disease in older people, whilst anxiety disorders were significantly associated with thyroid, GORD and other gastrointestinal disorders, and psoriasis. Increased odds of high medical burden were associated with both mood and anxiety disorders. Conclusions Our study provides further population-based evidence supporting the link between mental and physical illness in men. Understanding these associations is not only necessary for individual management, but also to inform the delivery of health promotion messages and health care. PMID:23618390

Fatigue lifetime prediction of a reduced-diameter dental implant system: Numerical and experimental study.

PubMed

Duan, Yuanyuan; Gonzalez, Jorge A; Kulkarni, Pratim A; Nagy, William W; Griggs, Jason A

2018-06-16

To validate the fatigue lifetime of a reduced-diameter dental implant system predicted by three-dimensional finite element analysis (FEA) by testing physical implant specimens using an accelerated lifetime testing (ALT) strategy with the apparatus specified by ISO 14801. A commercially-available reduced-diameter titanium dental implant system (Straumann Standard Plus NN) was digitized using a micro-CT scanner. Axial slices were processed using an interactive medical image processing software (Mimics) to create 3D models. FEA analysis was performed in ABAQUS, and fatigue lifetime was predicted using fe-safe ® software. The same implant specimens (n=15) were tested at a frequency of 2Hz on load frames using apparatus specified by ISO 14801 and ALT. Multiple step-stress load profiles with various aggressiveness were used to improve testing efficiency. Fatigue lifetime statistics of physical specimens were estimated in a reliability analysis software (ALTA PRO). Fractured specimens were examined using SEM with fractographic technique to determine the failure mode. FEA predicted lifetime was within the 95% confidence interval of lifetime estimated by experimental results, which suggested that FEA prediction was accurate for this implant system. The highest probability of failure was located at the root of the implant body screw thread adjacent to the simulated bone level, which also agreed with the failure origin in physical specimens. Fatigue lifetime predictions based on finite element modeling could yield similar results in lieu of physical testing, allowing the use of virtual testing in the early stages of future research projects on implant fatigue. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Assessing and forecasting population health: integrating knowledge and beliefs in a comprehensive framework.

PubMed

Van Meijgaard, Jeroen; Fielding, Jonathan E; Kominski, Gerald F

2009-01-01

A comprehensive population health-forecasting model has the potential to interject new and valuable information about the future health status of the population based on current conditions, socioeconomic and demographic trends, and potential changes in policies and programs. Our Health Forecasting Model uses a continuous-time microsimulation framework to simulate individuals' lifetime histories by using birth, risk exposures, disease incidence, and death rates to mark changes in the state of the individual. The model generates a reference forecast of future health in California, including details on physical activity, obesity, coronary heart disease, all-cause mortality, and medical expenditures. We use the model to answer specific research questions, inform debate on important policy issues in public health, support community advocacy, and provide analysis on the long-term impact of proposed changes in policies and programs, thus informing stakeholders at all levels and supporting decisions that can improve the health of populations.

Associations between attention deficit hyperactivity disorder symptom domains and DSM-IV lifetime substance dependence.

PubMed

Ameringer, Katherine J; Leventhal, Adam M

2013-01-01

Most studies of attention deficit hyperactivity disorder (ADHD) in the substance dependence literature have assessed ADHD as a single, categorical entity. This approach limits characterization across the spectrum of ADHD symptomatology and may mask differences across the two core domains of ADHD symptoms-hyperactive-impulsive (HI) and inattention (IN). Further, it is unclear whether relations of HI and IN symptoms to substance dependence extend across drug classes and to the general population. This cross-sectional study investigated associations of lifetime ADHD HI and IN symptom levels to individual classes of lifetime substance dependence (alcohol, nicotine, depressants, opioids, stimulants, cannabis, hallucinogens, polysubstance) in a population-based sample of 34,653 American adults. HI and IN were associated with the majority of dependence diagnoses in a linear pattern, such that each additional symptom was associated with a proportional increase in odds of dependence. After adjusting for the overlap between symptom domains, both HI and IN uniquely associated with alcohol, nicotine, and polysubstance dependence, but only HI uniquely associated with dependence on illicit substances. These findings suggest that individuals in the general population with elevated levels of ADHD (particularly HI) symptoms are at risk for various forms of substance dependence and could benefit from preventive interventions. Copyright © American Academy of Addiction Psychiatry.

Associations between Attention Deficit Hyperactivity Disorder Symptom Domains and DSM-IV Lifetime Substance Dependence

PubMed Central

Ameringer, Katherine J.; Leventhal, Adam M.

2013-01-01

Background and Objectives Most studies of attention deficit hyperactivity disorder (ADHD) in the substance dependence literature have assessed ADHD as a single, categorical entity. This approach limits characterization across the spectrum of ADHD symptomatology and may mask differences across the two core domains of ADHD symptoms—hyperactive-impulsive (HI) and inattention (IN). Further, it is unclear whether relations of HI and IN symptoms to substance dependence extend across drug classes and to the general population. Methods This cross-sectional study investigated associations of lifetime ADHD HI and IN symptom levels to individual classes of lifetime substance dependence (alcohol, nicotine, depressants, opioids, stimulants, cannabis, hallucinogens, polysubstance) in a population-based sample of 34,653 American adults. Results HI and IN were associated with the majority of dependence diagnoses in a linear pattern, such that each additional symptom was associated with a proportional increase in odds of dependence. After adjusting for the overlap between symptom domains, both HI and IN uniquely associated with alcohol, nicotine, and polysubstance dependence, but only HI uniquely associated with dependence on illicit substances. Conclusions and Scientific Significance These findings suggest that individuals in the general population with elevated levels of ADHD (particularly HI) symptoms are at risk for various forms of substance dependence and could benefit from preventive interventions. PMID:23398223

SIRTF thermal design modifications to increase lifetime

NASA Astrophysics Data System (ADS)

Petrick, S. W.

1993-01-01

An effort was made to increase the predicted lifetime of the SIRTF dewar by lowering the exterior shell temperature, increasing the radiated energy from the vapor cooled shields and reconfiguring the vapor cooled shields. The lifetime increases can be used to increase the scientific return from the mission and as a trade-off against mass and cost. This paper describes the configurations studied, the steady state thermal model used, the analytical methods and the results of the analysis. Much of the heat input to the outside dewar shell is radiative heat transfer from the solar panel. To lower the shell temperature, radiative cooled shields were placed between the solar panel and the dewar shell and between the bus and the dewar shell. Analysis showed that placing a radiator on the outer vapor cooled shield had a significant effect on lifetime. Lengthening the distance between the outer shell and the point where the vapor cooled shields are attached to the support straps also improved lifetime.

Polymer damage mitigation---predictive lifetime models of polymer insulation degradation and biorenewable thermosets through cationic polymerization for self-healing applications

NASA Astrophysics Data System (ADS)

Hondred, Peter Raymond

Over the past 50 years, the industrial development and applications for polymers and polymer composites has become expansive. However, as with any young technology, the techniques for predicting material damage and resolving material failure are in need of continued development and refinement. This thesis work takes two approaches to polymer damage mitigation---material lifetime prediction and spontaneous damage repair through self-healing while incorporating bio-renewable feedstock. First, material lifetime prediction offers the benefit of identifying and isolating material failures before the effects of damage results in catastrophic failure. Second, self-healing provides a systematic approach to repairing damaged polymer composites, specifically in applications where a hands-on approach or removing the part from service are not feasible. With regard to lifetime prediction, we investigated three specific polymeric materials---polytetrafluoroethylene (PTFE), poly(ethylene-alt-tetrafluoroethylene) (ETFE), and Kapton. All three have been utilized extensively in the aerospace field as a wire insulation coating. Because of the vast amount of electrical wiring used in aerospace constructions and the potential for electrical and thermal failure, this work develops mathematical models for both the thermal degradation kinetics as well as a lifetime prediction model for electrothermal breakdown. Isoconversional kinetic methods, which plot activation energy as a function of the extent of degradation, present insight into the development each kinetic model. The models for PTFE, ETFE, and Kapton are one step, consecutive three-step, and competitive and consecutive five-step respectively. Statistical analysis shows that an nth order autocatalytic reaction best defined the reaction kinetics for each polymer's degradation. Self-healing polymers arrest crack propagation through the use of an imbedded adhesive that reacts when cracks form. This form of damage mitigation focuses on

Estimating and modelling cure in population-based cancer studies within the framework of flexible parametric survival models.

PubMed

Andersson, Therese M L; Dickman, Paul W; Eloranta, Sandra; Lambert, Paul C

2011-06-22

When the mortality among a cancer patient group returns to the same level as in the general population, that is, the patients no longer experience excess mortality, the patients still alive are considered "statistically cured". Cure models can be used to estimate the cure proportion as well as the survival function of the "uncured". One limitation of parametric cure models is that the functional form of the survival of the "uncured" has to be specified. It can sometimes be hard to find a survival function flexible enough to fit the observed data, for example, when there is high excess hazard within a few months from diagnosis, which is common among older age groups. This has led to the exclusion of older age groups in population-based cancer studies using cure models. Here we have extended the flexible parametric survival model to incorporate cure as a special case to estimate the cure proportion and the survival of the "uncured". Flexible parametric survival models use splines to model the underlying hazard function, and therefore no parametric distribution has to be specified. We have compared the fit from standard cure models to our flexible cure model, using data on colon cancer patients in Finland. This new method gives similar results to a standard cure model, when it is reliable, and better fit when the standard cure model gives biased estimates. Cure models within the framework of flexible parametric models enables cure modelling when standard models give biased estimates. These flexible cure models enable inclusion of older age groups and can give stage-specific estimates, which is not always possible from parametric cure models. © 2011 Andersson et al; licensee BioMed Central Ltd.

Label-free identification of macrophage phenotype by fluorescence lifetime imaging microscopy

NASA Astrophysics Data System (ADS)

Alfonso-García, Alba; Smith, Tim D.; Datta, Rupsa; Luu, Thuy U.; Gratton, Enrico; Potma, Eric O.; Liu, Wendy F.

2016-04-01

Macrophages adopt a variety of phenotypes that are a reflection of the many functions they perform as part of the immune system. In particular, metabolism is a phenotypic trait that differs between classically activated, proinflammatory macrophages, and alternatively activated, prohealing macrophages. Inflammatory macrophages have a metabolism based on glycolysis while alternatively activated macrophages generally rely on oxidative phosphorylation to generate chemical energy. We employ this shift in metabolism as an endogenous marker to identify the phenotype of individual macrophages via live-cell fluorescence lifetime imaging microscopy (FLIM). We demonstrate that polarized macrophages can be readily discriminated with the aid of a phasor approach to FLIM, which provides a fast and model-free method for analyzing fluorescence lifetime images.

Cosmological constraints on the neutron lifetime

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

Salvati, L.; Pagano, L.; Melchiorri, A.

2016-03-01

We derive new constraints on the neutron lifetime based on the recent Planck 2015 observations of temperature and polarization anisotropies of the CMB. Under the assumption of standard Big Bang Nucleosynthesis, we show that Planck data constrains the neutron lifetime to τ{sub n} = (907±69) [s] at 68% c.l.. Moreover, by including the direct measurements of primordial Helium abundance of Aver et al. (2015) and Izotov et al. (2014), we show that cosmological data provide the stringent constraints τ{sub n} = (875±19) [s] and τ{sub n} = (921±11) [s] respectively. The latter appears to be in tension with neutron lifetime value quoted by the Particle Data Group (τ{sub n} = (880.3±1.1) [s]).more » Future CMB surveys as COrE+, in combination with a weak lensing survey as EUCLID, could constrain the neutron lifetime up to a ∼ 6 [s] precision.« less

Velocity-based movement modeling for individual and population level inference

USGS Publications Warehouse

Hanks, Ephraim M.; Hooten, Mevin B.; Johnson, Devin S.; Sterling, Jeremy T.

2011-01-01

Understanding animal movement and resource selection provides important information about the ecology of the animal, but an animal's movement and behavior are not typically constant in time. We present a velocity-based approach for modeling animal movement in space and time that allows for temporal heterogeneity in an animal's response to the environment, allows for temporal irregularity in telemetry data, and accounts for the uncertainty in the location information. Population-level inference on movement patterns and resource selection can then be made through cluster analysis of the parameters related to movement and behavior. We illustrate this approach through a study of northern fur seal (Callorhinus ursinus) movement in the Bering Sea, Alaska, USA. Results show sex differentiation, with female northern fur seals exhibiting stronger response to environmental variables.