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Sample records for survival function estimator

  1. ESTIMATION OF SURVIVAL FUNCTION BASED ON MODELING OF CENSORING PATTERN

    OpenAIRE

    Akio, Suzukawa; Nobuhiro, Taneichi; Department of Animal Production and Agricultural Economics, Obihiro University

    2000-01-01

    The Kaplan-Meier estimator(KM-estimator)is an important tool in the analysis of right censored data. It is a non-parametric estimator of an unknown survival function of a lifetime random variable. The purpose of this paper is to obtain a semi-parametric estimator of the survival function. In many practical data, there are several patterns of censoring, for example, censoring is apt to occur for the larger observable time. Such a pattern can be expressed by a function defined by conditional pr...

  2. A method of moments to estimate bivariate survival functions: the copula approach

    Directory of Open Access Journals (Sweden)

    Silvia Angela Osmetti

    2013-05-01

    Full Text Available In this paper we discuss the problem on parametric and non parametric estimation of the distributions generated by the Marshall-Olkin copula. This copula comes from the Marshall-Olkin bivariate exponential distribution used in reliability analysis. We generalize this model by the copula and different marginal distributions to construct several bivariate survival functions. The cumulative distribution functions are not absolutely continuous and they unknown parameters are often not be obtained in explicit form. In order to estimate the parameters we propose an easy procedure based on the moments. This method consist in two steps: in the first step we estimate only the parameters of marginal distributions and in the second step we estimate only the copula parameter. This procedure can be used to estimate the parameters of complex survival functions in which it is difficult to find an explicit expression of the mixed moments. Moreover it is preferred to the maximum likelihood one for its simplex mathematic form; in particular for distributions whose maximum likelihood parameters estimators can not be obtained in explicit form.

  3. Demographic window to aging in the wild: constructing life tables and estimating survival functions from marked individuals of unknown age.

    Science.gov (United States)

    Müller, Hans-Georg; Wang, Jane-Ling; Carey, James R; Caswell-Chen, Edward P; Chen, Carl; Papadopoulos, Nikos; Yao, Fang

    2004-06-01

    Summary We address the problem of establishing a survival schedule for wild populations. A demographic key identity is established, leading to a method whereby age-specific survival and mortality can be deduced from a marked cohort life table established for individuals that are randomly sampled at unknown age and marked, with subsequent recording of time-to-death. This identity permits the construction of life tables from data where the birth date of subjects is unknown. An analogous key identity is established for the continuous case in which the survival schedule of the wild population is related to the density of the survival distribution in the marked cohort. These identities are explored for both life tables and continuous lifetime data. For the continuous case, they are implemented with statistical methods using non-parametric density estimation methods to obtain flexible estimates for the unknown survival distribution of the wild population. The analytical model provided here serves as a starting point to develop more complex models for residual demography, i.e. models for estimating survival of wild populations in which age-at-entry is unknown and using remaining information in randomly encountered individuals. This is a first step towards a broad new concept of 'expressed demographic information content of marked or captured individuals'. Copyright 2004 Blackwell Publishing Ltd.

  4. Relationships between mastitis and functional longevity in Danish Black and White dairy cattle estimated using survival analysis

    NARCIS (Netherlands)

    Neerhof, H.J.; Madsen, P.; Ducrucq, V.; Vollema, A.R.; Jensen, I.; Korsgaard, I.R.

    2000-01-01

    The relationship between mastitis and functional longevity was assessed with survival analysis on data of Danish Black and White dairy cows. Different methods of including the effect of mastitis treatment on the culling decision by a farmer in the model were compared. The model in which mastitis

  5. Efficient estimation of semiparametric copula models for bivariate survival data

    KAUST Repository

    Cheng, Guang

    2014-01-01

    A semiparametric copula model for bivariate survival data is characterized by a parametric copula model of dependence and nonparametric models of two marginal survival functions. Efficient estimation for the semiparametric copula model has been recently studied for the complete data case. When the survival data are censored, semiparametric efficient estimation has only been considered for some specific copula models such as the Gaussian copulas. In this paper, we obtain the semiparametric efficiency bound and efficient estimation for general semiparametric copula models for possibly censored data. We construct an approximate maximum likelihood estimator by approximating the log baseline hazard functions with spline functions. We show that our estimates of the copula dependence parameter and the survival functions are asymptotically normal and efficient. Simple consistent covariance estimators are also provided. Numerical results are used to illustrate the finite sample performance of the proposed estimators. © 2013 Elsevier Inc.

  6. Demographic window to aging in the wild: constructing life tables and estimating survival functions from marked individuals of unknown age

    OpenAIRE

    Müller, Hans-Georg; Wang, Jane-Ling; Carey, James R.; Caswell-Chen, Edward P.; Chen, Carl; Papadopoulos, Nikos; Yao, Fang

    2004-01-01

    We address the problem of establishing a survival schedule for wild populations. A demographic key identity is established, leading to a method whereby age-specific survival and mortality can be deduced from a marked cohort life table established for individuals that are randomly sampled at unknown age and marked, with subsequent recording of time-to-death. This identity permits the construction of life tables from data where the birth date of subjects is unknown. An analogous key identity is...

  7. Contrasting treatment-specific survival using double-robust estimators.

    Science.gov (United States)

    Zhang, Min; Schaubel, Douglas E

    2012-12-30

    In settings where a randomized trial is infeasible, observational data are frequently used to compare treatment-specific survival. The average causal effect (ACE) can be used to make inference regarding treatment policies on patient populations, and a valid ACE estimator must account for imbalances with respect to treatment-specific covariate distributions. One method through which the ACE on survival can be estimated involves appropriately averaging over Cox-regression-based fitted survival functions. A second available method balances the treatment-specific covariate distributions through inverse probability of treatment weighting and then contrasts weighted nonparametric survival function estimators. Because both methods have their advantages and disadvantages, we propose methods that essentially combine both estimators. The proposed methods are double robust, in the sense that they are consistent if at least one of the two working regression models (i.e., logistic model for treatment and Cox model for death hazard) is correct. The proposed methods involve estimating the ACE with respect to restricted mean survival time, defined as the area under the survival curve up to some prespecified time point. We derive and evaluate asymptotic results through simulation. We apply the proposed methods to estimate the ACE of donation-after-cardiac-death kidney transplantation with the use of data obtained from multiple centers in the Netherlands. Copyright © 2012 John Wiley & Sons, Ltd.

  8. Estimating haplotype effects for survival data

    DEFF Research Database (Denmark)

    Scheike, Thomas; Martinussen, Torben; Silver, J

    2010-01-01

    Genetic association studies often investigate the effect of haplotypes on an outcome of interest. Haplotypes are not observed directly, and this complicates the inclusion of such effects in survival models. We describe a new estimating equations approach for Cox's regression model to assess haplo...... in this article to investigate possible haplotype effects of the PAF-receptor on cardiovascular events in patients with coronary artery disease, and compare our results to those based on the EM algorithm....

  9. Attributing death to cancer: cause-specific survival estimation.

    Directory of Open Access Journals (Sweden)

    Mathew A

    2002-10-01

    Full Text Available Cancer survival estimation is an important part of assessing the overall strength of cancer care in a region. Generally, the death of a patient is taken as the end point in estimation of overall survival. When calculating the overall survival, the cause of death is not taken into account. With increasing demand for better survival of cancer patients it is important for clinicians and researchers to know about survival statistics due to disease of interest, i.e. net survival. It is also important to choose the best method for estimating net survival. Increase in the use of computer programmes has made it possible to carry out statistical analysis without guidance from a bio-statistician. This is of prime importance in third- world countries as there are a few trained bio-statisticians to guide clinicians and researchers. The present communication describes current methods used to estimate net survival such as cause-specific survival and relative survival. The limitation of estimation of cause-specific survival particularly in India and the usefulness of relative survival are discussed. The various sources for estimating cancer survival are also discussed. As survival-estimates are to be projected on to the population at large, it becomes important to measure the variation of the estimates, and thus confidence intervals are used. Rothman′s confidence interval gives the most satisfactory result for survival estimate.

  10. Robustness of survival estimates for radio-marked animals

    Science.gov (United States)

    Bunck, C.M.; Chen, C.-L.

    1992-01-01

    Telemetry techniques are often used to study the survival of birds and mammals; particularly whcn mark-recapture approaches are unsuitable. Both parametric and nonparametric methods to estimate survival have becn developed or modified from other applications. An implicit assumption in these approaches is that the probability of re-locating an animal with a functioning transmitter is one. A Monte Carlo study was conducted to determine the bias and variance of the Kaplan-Meier estimator and an estimator based also on the assumption of constant hazard and to eva!uate the performance of the two-sample tests associated with each. Modifications of each estimator which allow a re-Iocation probability of less than one are described and evaluated. Generallv the unmodified estimators were biased but had lower variance. At low sample sizes all estimators performed poorly. Under the null hypothesis, the distribution of all test statistics reasonably approximated the null distribution when survival was low but not when it was high. The power of the two-sample tests were similar.

  11. Cost function estimation

    DEFF Research Database (Denmark)

    Andersen, C K; Andersen, K; Kragh-Sørensen, P

    2000-01-01

    Statistical analysis of cost data is often difficult because of highly skewed data resulting from a few patients who incur high costs relative to the majority of patients. When the objective is to predict the cost for an individual patient, the literature suggests that one should choose...... on these criteria, a two-part model was chosen. In this model, the probability of incurring any costs was estimated using a logistic regression, while the level of the costs was estimated in the second part of the model. The choice of model had a substantial impact on the predicted health care costs, e...... a regression model based on the quality of its predictions. In exploring the econometric issues, the objective of this study was to estimate a cost function in order to estimate the annual health care cost of dementia. Using different models, health care costs were regressed on the degree of dementia, sex, age...

  12. Instrumental variable estimation in a survival context

    DEFF Research Database (Denmark)

    Tchetgen Tchetgen, Eric J; Walter, Stefan; Vansteelandt, Stijn

    2015-01-01

    . In this approach, the fitted value from a first-stage regression of the exposure on the IV is entered in place of the exposure in the second-stage hazard model to recover a valid estimate of the treatment effect of interest. The second method is a so-called control function approach, which entails adding...... to the additive hazards outcome model, the residual from a first-stage regression of the exposure on the IV. Formal conditions are given justifying each strategy, and the methods are illustrated in a novel application to a Mendelian randomization study to evaluate the effect of diabetes on mortality using data...

  13. Graphing survival curve estimates for time-dependent covariates.

    Science.gov (United States)

    Schultz, Lonni R; Peterson, Edward L; Breslau, Naomi

    2002-01-01

    Graphical representation of statistical results is often used to assist readers in the interpretation of the findings. This is especially true for survival analysis where there is an interest in explaining the patterns of survival over time for specific covariates. For fixed categorical covariates, such as a group membership indicator, Kaplan-Meier estimates (1958) can be used to display the curves. For time-dependent covariates this method may not be adequate. Simon and Makuch (1984) proposed a technique that evaluates the covariate status of the individuals remaining at risk at each event time. The method takes into account the change in an individual's covariate status over time. The survival computations are the same as the Kaplan-Meier method, in that the conditional survival estimates are the function of the ratio of the number of events to the number at risk at each event time. The difference between the two methods is that the individuals at risk within each level defined by the covariate is not fixed at time 0 in the Simon and Makuch method as it is with the Kaplan-Meier method. Examples of how the two methods can differ for time dependent covariates in Cox proportional hazards regression analysis are presented.

  14. On robustness of marginal regression coefficient estimates and hazard functions in multivariate survival analysis of family data when the frailty distribution is mis-specified.

    Science.gov (United States)

    Hsu, Li; Gorfine, Malka; Malone, Kathleen

    2007-11-10

    The shared frailty model is an extension of the Cox model to correlated failure times and, essentially, a random effects model for failure time outcomes. In this model, the latent frailty shared by individual members in a cluster acts multiplicatively as a factor on the hazard function and is typically modelled parametrically. One commonly used distribution is gamma, where both shape and scale parameters are set to be the same to allow for unique identification of baseline hazard function. It is popular because it is a conjugate prior, and the posterior distribution possesses the same form as gamma. In addition, the parameter can be interpreted as a time-independent cross-ratio function, a natural extension of odds ratio to failure time outcomes. In this paper, we study the effect of frailty distribution mis-specification on the marginal regression estimates and hazard functions under assumed gamma distribution with an application to family studies. The simulation results show that the biases are generally 10% and lower, even when the true frailty distribution deviates substantially from the assumed gamma distribution. This suggests that the gamma frailty model can be a practical choice in real data analyses if the regression parameters and marginal hazard function are of primary interest and individual cluster members are exchangeable with respect to their dependencies. Copyright 2007 John Wiley & Sons, Ltd.

  15. A global synthesis of survival estimates for microbats

    OpenAIRE

    Lentini, Pia E.; Bird, Tomas J.; Griffiths, Stephen R.; Godinho, Lisa N.; Wintle, Brendan A.

    2015-01-01

    Accurate survival estimates are needed to construct robust population models, which are a powerful tool for understanding and predicting the fates of species under scenarios of environmental change. Microbats make up 17% of the global mammalian fauna, yet the processes that drive differences in demographics between species are poorly understood. We collected survival estimates for 44 microbat species from the literature and constructed a model to determine the effects of reproductive, feeding...

  16. Survival estimates - Survival estimates for the passage of juvenile salmonids through Snake and Columbia River dams and reservoirs

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This BPA-funded study provides estimates of smolt survival and travel time through individual reaches and reaches combined in the Snake and Columbia Rivers...

  17. Challenges in the estimation of Net SURvival: The CENSUR working survival group.

    Science.gov (United States)

    Giorgi, R

    2016-10-01

    Net survival, the survival probability that would be observed, in a hypothetical world, where the cancer of interest would be the only possible cause of death, is a key indicator in population-based cancer studies. Accounting for mortality due to other causes, it allows cross-country comparisons or trends analysis and provides a useful indicator for public health decision-making. The objective of this study was to show how the creation and formalization of a network comprising established research teams, which already had substantial and complementary experience in both cancer survival analysis and methodological development, make it possible to meet challenges and thus provide more adequate tools, to improve the quality and the comparability of cancer survival data, and to promote methodological transfers in areas of emerging interest. The Challenges in the Estimation of Net SURvival (CENSUR) working survival group is composed of international researchers highly skilled in biostatistics, methodology, and epidemiology, from different research organizations in France, the United Kingdom, Italy, Slovenia, and Canada, and involved in French (FRANCIM) and European (EUROCARE) cancer registry networks. The expected advantages are an interdisciplinary, international, synergistic network capable of addressing problems in public health, for decision-makers at different levels; tools for those in charge of net survival analyses; a common methodology that makes unbiased cross-national comparisons of cancer survival feasible; transfer of methods for net survival estimations to other specific applications (clinical research, occupational epidemiology); and dissemination of results during an international training course. The formalization of the international CENSUR working survival group was motivated by a need felt by scientists conducting population-based cancer research to discuss, develop, and monitor implementation of a common methodology to analyze net survival in order

  18. Estimating haplotype relative risks on human survival in population-based association studies.

    Science.gov (United States)

    Tan, Qihua; Christiansen, Lene; Bathum, Lise; Zhao, Jing Hua; Yashin, Anatoli I; Vaupel, James W; Christensen, Kaare; Kruse, Torben A

    2005-01-01

    Association-based linkage disequilibrium (LD) mapping is an increasingly important tool for localizing genes that show potential influence on human aging and longevity. As haplotypes contain more LD information than single markers, a haplotype-based LD approach can have increased power in detecting associations as well as increased robustness in statistical testing. In this paper, we develop a new statistical model to estimate haplotype relative risks (HRRs) on human survival using unphased multilocus genotype data from unrelated individuals in cross-sectional studies. Based on the proportional hazard assumption, the model can estimate haplotype risk and frequency parameters, incorporate observed covariates, assess interactions between haplotypes and the covariates, and investigate the modes of gene function. By introducing population survival information available from population statistics, we are able to develop a procedure that carries out the parameter estimation using a nonparametric baseline hazard function and estimates sex-specific HRRs to infer gene-sex interaction. We also evaluate the haplotype effects on human survival while taking into account individual heterogeneity in the unobserved genetic and nongenetic factors or frailty by introducing the gamma-distributed frailty into the survival function. After model validation by computer simulation, we apply our method to an empirical data set to measure haplotype effects on human survival and to estimate haplotype frequencies at birth and over the observed ages. Results from both simulation and model application indicate that our survival analysis model is an efficient method for inferring haplotype effects on human survival in population-based association studies.

  19. Functional status and survival after kidney transplantation1–12

    Science.gov (United States)

    Reese, Peter P.; Bloom, Roy D.; Shults, Justine; Thomasson, Arwin; Mussell, Adam; Rosas, Sylvia E.; Johansen, Kirsten L.; Abt, Peter; Levine, Matthew; Caplan, Arthur; Feldman, Harold I.; Karlawish, Jason

    2013-01-01

    Background Older patients constitute a growing proportion of U.S. kidney transplant recipients and often have a high burden of comorbidities. A summary measure of health such as functional status might enable transplant professionals to better evaluate and counsel these patients about their prognosis after transplant. Methods We linked UNOS registry data about post-transplant survival with pre-transplant functional status data (physical function [PF] scale of the Medical Outcomes Study Short Form-36) among individuals undergoing kidney transplant from 6/1/2000 – 5/31/2006. We examined the relationship between survival and functional status with multivariable Cox regression, adjusted for age. Using logistic regression models for three-year survival, we also estimated the reduction in deaths in the hypothetical scenario that recipients with poor functional status in this cohort experienced modest improvements in function. Results The cohort comprised 10,875 kidney transplant recipients (KTRs) with a mean age of 50 years; 14% were ≥65. Differences in three-year mortality between highest and lowest PF groups ranged from 3% among recipients <35 years to 14% among recipients ≥65 years. In multivariable Cox regression, worse PF was associated with higher mortality (HR 1.66 for lowest versus highest PF quartiles; p<0.001). Interactions between PF and age were non-significant. We estimated that 11% fewer deaths would occur if KTRs with the lowest functional status experienced modest improvements in function. Conclusions Across a wide age range, functional status was an independent predictor of post-transplant survival. Functional status assessment may be a useful tool with which to counsel patients about post-transplant outcomes. PMID:24113514

  20. A global synthesis of survival estimates for microbats.

    Science.gov (United States)

    Lentini, Pia E; Bird, Tomas J; Griffiths, Stephen R; Godinho, Lisa N; Wintle, Brendan A

    2015-08-01

    Accurate survival estimates are needed to construct robust population models, which are a powerful tool for understanding and predicting the fates of species under scenarios of environmental change. Microbats make up 17% of the global mammalian fauna, yet the processes that drive differences in demographics between species are poorly understood. We collected survival estimates for 44 microbat species from the literature and constructed a model to determine the effects of reproductive, feeding and demographic traits on survival. Our trait-based model indicated that bat species which produce more young per year exhibit lower apparent annual survival, as do males and juveniles compared with females and adults, respectively. Using 8 years of monitoring data for two Australian species, we demonstrate how knowledge about the effect of traits on survival can be incorporated into Bayesian survival analyses. This approach can be applied to any group and is not restricted to bats or even mammals. The incorporation of informative priors based on traits can allow for more timely construction of population models to support management decisions and actions. © 2015 The Author(s).

  1. Function Estimation Employing Exponential Splines

    Science.gov (United States)

    Dose, V.; Fischer, R.

    2005-11-01

    We introduce and discuss the use of the exponential spline family for Bayesian nonparametric function estimation. Exponential splines span the range of shapes between the limiting cases of traditional cubic spline and piecewise linear interpolation. They are therefore particularly suited for problems where both, smooth and rapid function changes occur.

  2. Estimated Glomerular Filtration Rate and Risk of Survival in Acute ...

    African Journals Online (AJOL)

    Objective: To assess the risk of survival in acute stroke using the MDRD equation derived estimated glomerular filtration rate. Design: A prospective observational cross-sectional study. Setting: Medical wards of a tertiary care hospital. Subjects: Eighty three acute stroke patients had GFR calculated within 48 hours of ...

  3. Semiparametric Maximum Likelihood Estimation in Normal Transformation Models for Bivariate Survival Data

    Science.gov (United States)

    Li, Yi; Prentice, Ross L.; Lin, Xihong

    2008-01-01

    SUMMARY We consider a class of semiparametric normal transformation models for right censored bivariate failure times. Nonparametric hazard rate models are transformed to a standard normal model and a joint normal distribution is assumed for the bivariate vector of transformed variates. A semiparametric maximum likelihood estimation procedure is developed for estimating the marginal survival distribution and the pairwise correlation parameters. This produces an efficient estimator of the correlation parameter of the semiparametric normal transformation model, which characterizes the bivariate dependence of bivariate survival outcomes. In addition, a simple positive-mass-redistribution algorithm can be used to implement the estimation procedures. Since the likelihood function involves infinite-dimensional parameters, the empirical process theory is utilized to study the asymptotic properties of the proposed estimators, which are shown to be consistent, asymptotically normal and semiparametric efficient. A simple estimator for the variance of the estimates is also derived. The finite sample performance is evaluated via extensive simulations. PMID:19079778

  4. Semiparametric Maximum Likelihood Estimation in Normal Transformation Models for Bivariate Survival Data.

    Science.gov (United States)

    Li, Yi; Prentice, Ross L; Lin, Xihong

    2008-12-01

    We consider a class of semiparametric normal transformation models for right censored bivariate failure times. Nonparametric hazard rate models are transformed to a standard normal model and a joint normal distribution is assumed for the bivariate vector of transformed variates. A semiparametric maximum likelihood estimation procedure is developed for estimating the marginal survival distribution and the pairwise correlation parameters. This produces an efficient estimator of the correlation parameter of the semiparametric normal transformation model, which characterizes the bivariate dependence of bivariate survival outcomes. In addition, a simple positive-mass-redistribution algorithm can be used to implement the estimation procedures. Since the likelihood function involves infinite-dimensional parameters, the empirical process theory is utilized to study the asymptotic properties of the proposed estimators, which are shown to be consistent, asymptotically normal and semiparametric efficient. A simple estimator for the variance of the estimates is also derived. The finite sample performance is evaluated via extensive simulations.

  5. Hidden Markov model for dependent mark loss and survival estimation

    Science.gov (United States)

    Laake, Jeffrey L.; Johnson, Devin S.; Diefenbach, Duane R.; Ternent, Mark A.

    2014-01-01

    Mark-recapture estimators assume no loss of marks to provide unbiased estimates of population parameters. We describe a hidden Markov model (HMM) framework that integrates a mark loss model with a Cormack–Jolly–Seber model for survival estimation. Mark loss can be estimated with single-marked animals as long as a sub-sample of animals has a permanent mark. Double-marking provides an estimate of mark loss assuming independence but dependence can be modeled with a permanently marked sub-sample. We use a log-linear approach to include covariates for mark loss and dependence which is more flexible than existing published methods for integrated models. The HMM approach is demonstrated with a dataset of black bears (Ursus americanus) with two ear tags and a subset of which were permanently marked with tattoos. The data were analyzed with and without the tattoo. Dropping the tattoos resulted in estimates of survival that were reduced by 0.005–0.035 due to tag loss dependence that could not be modeled. We also analyzed the data with and without the tattoo using a single tag. By not using.

  6. Thyroid function and survival following breast cancer.

    Science.gov (United States)

    Brandt, J; Borgquist, S; Almquist, M; Manjer, J

    2016-11-01

    Thyroid function has been associated with breast cancer risk, and breast cancer cell growth and proliferation. It is not clear whether thyroid function affects prognosis following breast cancer but, if so, this could have an important clinical impact. The present study analysed prospectively collected measurements of free tri-iodothyronine (T3), free thyroxine (T4), thyroid-stimulating hormone (TSH) and thyroid peroxidase antibodies (TPO-Ab) in relation to breast cancer survival. The Malmö Diet and Cancer Study is a prospective cohort study of 17 035 women in Sweden. Study enrolment was conducted between 1991 and 1996. Patients with incident breast cancer were identified through record linkage with cancer registries until 31 December 2006. Information on vital status was collected from the Swedish Cause of Death Registry, with the endpoint breast cancer mortality (31 December 2013). Hazard ratios (HRs) with 95 per cent confidence intervals (c.i.) were obtained by Cox proportional hazards analysis. Some 766 patients with incident breast cancer were identified, of whom 551 were eligible for analysis. Compared with patients in the first free T4 tertile, breast cancer mortality was lower among those in the second tertile (HR 0·49, 95 per cent c.i. 0·28 to 0·84). There was an indication, although non-significant, of lower breast cancer mortality among patients in the second TSH tertile (HR 0·63, 0·37 to 1·09) and in those with positive TPO-Ab status (HR 0·61, 0·30 to 1·23). Free T3 showed no clear association with mortality. In the present study, there was a positive association between free T4 levels and improved breast cancer survival. © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd.

  7. Cancer estimation of incidence and survival in Algeria 2014

    Directory of Open Access Journals (Sweden)

    Hamdi Cherif M

    2015-10-01

    Full Text Available Cancer is one of the major public health problems in Algeria. In the last 25 years, a significant increase in the incidence of the major types of cancers has been observed in both sexes. Moreover, the 5-year survival rate is low for the severe tumors due to a difficulty in access to cancer care and an incomplete health care framework. Cancer Registry of Setif, Algeria, has been recording cancer incidence, mortality, and survival since 1986 in collaboration with International Agency for Research on Cancer (IARC of Lyon. Cancer Registry of Setif is being a source of information for cancer planning and corresponding surveillance in the National Cancer Plan 2015-2019, starting in January 2015. Data is recorded by means of CanReg 5 software. This software is developed and provided by the International Agency for Research on Cancer (IARC of Lyon. It is designed specifically for cancer registration, and standardized to capture, control, and process the data. Estimation of cancer incidence in Algeria and survival rates are very important for surveillance, control, and planning of care. In men the incidence of lung, colorectal, bladder, prostate, and laryngeal cancers has significantly and steadily increased in the last decade. In women, the incidence of breast, colorectal, thyroid, and lung cancers has also increased significantly in the same period. Five-year survival rates for cancer of the stomach, colon, rectum, liver, lung, breast, cervix, ovary, and prostate in adults, and childhood leukemia are relatively low compared with other countries. The aim of our study was to estimate incidence and survival by means of Setif cancer registry data.

  8. Summarising censored survival data using the mean residual life function.

    Science.gov (United States)

    Alvarez-Iglesias, Alberto; Newell, John; Scarrott, Carl; Hinde, John

    2015-05-20

    The mean residual life function provides a clear and simple summary of the effect of a treatment or a risk factor in units of time, avoiding hazard ratios or probability scales, which require careful interpretation. Estimation of the mean residual life is complicated by the upper tail of the survival distribution not being observed as, for example, patients may still be alive at the end of the follow-up period. Various approaches have been developed to estimate the mean residual life in the presence of such right censoring. In this work, a novel semi-parametric method that combines existing non-parametric methods and an extreme value tail model is presented, where the limited sample information in the tail (prior to study termination) is used to estimate the upper tail behaviour. This approach will be demonstrated with simulated and real-life examples. Copyright © 2015 John Wiley & Sons, Ltd.

  9. A new approach to the "apparent survival" problem: estimating true survival rates from mark-recapture studies.

    Science.gov (United States)

    Gilroy, James J; Virzi, Thomas; Boulton, Rebecca L; Lockwood, Julie L

    2012-07-01

    Survival estimates generated from live capture-mark-recapture studies may be negatively biased due to the permanent emigration of marked individuals from the study area. In the absence of a robust analytical solution, researchers typically sidestep this problem by simply reporting estimates using the term "apparent survival." Here, we present a hierarchical Bayesian multistate model designed to estimate true survival by accounting for predicted rates of permanent emigration. Initially we use dispersal kernels to generate spatial projections of dispersal probability around each capture location. From these projections, we estimate emigration probability for each marked individual and use the resulting values to generate bias-adjusted survival estimates from individual capture histories. When tested using simulated data sets featuring variable detection probabilities, survival rates, and dispersal patterns, the model consistently eliminated negative biases shown by apparent survival estimates from standard models. When applied to a case study concerning juvenile survival in the endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis), bias-adjusted survival estimates increased more than twofold above apparent survival estimates. Our approach is applicable to any capture-mark-recapture study design and should be particularly valuable for organisms with dispersive juvenile life stages.

  10. Estimating true instead of apparent survival using spatial Cormack-Jolly-Seber models

    Science.gov (United States)

    Schaub, Michael; Royle, J. Andrew

    2014-01-01

    Survival is often estimated from capture–recapture data using Cormack–Jolly–Seber (CJS) models, where mortality and emigration cannot be distinguished, and the estimated apparent survival probability is the product of the probabilities of true survival and of study area fidelity. Consequently, apparent survival is lower than true survival unless study area fidelity equals one. Underestimation of true survival from capture–recapture data is a main limitation of the method.

  11. Estimation of diver survival time in a lost bell

    Energy Technology Data Exchange (ETDEWEB)

    Tipton, M.J.; Franks, C. [Surrey Univ., Guildford (United Kingdom); Meneilly, G.S. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Medicine; Mekjavic, I.B. [Simon Fraser University, Vancouver (Canada). Dept. of Kinesiology

    1997-04-01

    Mathematical models of the human thermoregulatory system have been used to make predictions of the likely survival of divers in a ``lost bell`` who can be exposed to very low ambient temperatures. The circumstances considered are not the most extreme but those where, partly by shivering, the individual can re-enter thermal balance. The ability accurately to predict the level and duration of metabolic heat production is critical for the estimation of survival time under these conditions. Limitations on the accuracy of current models arise from the lack of precision in modelling the intensity and duration of the metabolic (shivering) response. A different basis for predicting shivering endurance using the time to hypogylcaemia (blood glucose level less than 2.5 mmol/1) is proposed. This leads to predicted survival times ranging from 10 to over 24 hours for those individuals able to stabilise deep body temperature. This seems to be more consistent with the limited experimental data which exists than the 8-9 hours predicted by other models. In order to help maintain blood sugar levels, and hence metabolic heat production, it is recommended that emergency rations within bells should provide 500g of carbohydrate a day. (59 figures; 221 references). (UK)

  12. SURVIVAL ESTIMATES OF BYCATCH INDIVIDUALS DISCARDED FROM BIVALVE DREDGES

    Directory of Open Access Journals (Sweden)

    Francisco Leitão

    2014-12-01

    Full Text Available The fate of released bycatch is an issue of great interest for fisheries research and management. Survival experiments were carried out to assess the survival capacity of animals damaged and discarded during clam dredging operations. Three common bycatch species, two fish (Trachinus vipera; Dicologlossa cuneata and one crab (Polybius henslowii, were collected during the sorting of catches from a commercial dredging boat. An arbitrary score scale was used to quantify the type and extent of damage to the organisms. Onboard, damaged individuals were placed in tanks containing seawater which were subsequently transferred to the laboratory. Survival experiments were conducted during the subsequent 48h. D. cuneata exhibited the lowest mortality after 48h (54%, followed by P. henslowii (65% and T. vipera (81%. Despite the magnitude of the percentage mortalities determined, the average number of individuals estimated to die during a 15 minutes tow (standard commercial fishing time was relatively small: 1.2, 3.24 and 11 for D. cuneata, T. vipera and P. henslowii, respectively. Nevertheless, when these figures are extrapolated to cover all the dredging fleet the impact of this practice on the populations of the species studied can be significant, particulary for D. cuneata.

  13. REML and ML estimation for clustered grouped survival data.

    Science.gov (United States)

    Lam, K F; Ip, David

    2003-06-30

    Clustered grouped survival data arise naturally in clinical medicine and biological research. For example, in a randomized clinical trial, the variable of interest is the time to occurrence of a certain event with or without a new treatment and the data are collected from possibly correlated subjects from independent clusters. However it is sometimes impossible or too expensive to monitor the experimental subjects continuously. The subjects are examined regularly and the continuous survival data are thus grouped into a discrete time scale. With such a design, researchers are mainly interested in the effectiveness of the new treatment as well as the correlation among subjects from the same cluster, namely the intracluster correlation. This paper suggests a random effects approach to the estimation of the regression parameter with various choices of regression model and also the dependence parameter which characterizes the intracluster correlation. Time dependent covariates can be accommodated in the proposed model, and the estimation procedure will not be further complicated with large cluster sizes. The proposed method is applied to the data from the Diabetic Retinopathy Study, the objective of which is to evaluate the effectiveness of laser photocoagulation in delaying or preventing the onset of blindness in the left and right eyes of individuals with diabetes-associated retinopathy. The intracluster correlation using a grouped proportional hazards regression model can be estimated and the relationship between the regression parameter estimates based on the random effects approach and the marginal approach using a dynamic logistic regression model are discussed. Results from a simulation study of the proposed method are also presented. Copyright 2003 John Wiley & Sons, Ltd.

  14. Microcomputer-assisted univariate survival data analysis using Kaplan-Meier life table estimators.

    Science.gov (United States)

    Campos-Filho, N; Franco, E L

    1988-01-01

    We describe a microcomputer program (KMSURV) for exploratory univariate statistical analysis of survival data which is directly applicable to the evaluation of clinical trials and to retrospective epidemiological studies of hospital registry-based data. The program calculates life-table-like information based on Kaplan-Meier's product-limit estimators of the survivorship function S(t) and provides summary measures of average survival times. In addition, two non-parametric tests for the comparison of survival distributions are performed. A report-quality, high resolution plot of the S(t) estimates for all groups being compared complements each set of analyses. KMSURV is not a simple adaptation of a mainframe statistical analysis package and, thus, it utilizes efficiently the interactive environment which is inherent in microcomputing.

  15. Cognitive function in families with exceptional survival

    DEFF Research Database (Denmark)

    Barral, Sandra; Cosentino, Stephanie; Costa, Rosann

    2012-01-01

    members in the offspring generation demonstrate significantly better performance on multiple tasks requiring attention, working memory, and semantic processing when compared with individuals without a family history of exceptional survival, suggesting that cognitive performance may serve as an important...

  16. Survival function of hypo-exponential distributions

    OpenAIRE

    Lotfy, Mamdouh M.; Abdelsamad, Ali S.

    1985-01-01

    Approved for public release; distribution is unlimited The reliability of a system is the probability that the system will survive or complete an intended mission of certain duration. Describing all possible ways that a system can survive a mission in reliability shorthand gives a simple approach to reliability computations. Reliability computation for a system defined by shorthand notation is greatly dependent upon the convolution problem. Assuming constant component failure rates, this p...

  17. Estimating An Aggregate Import Demand Function For Ghana ...

    African Journals Online (AJOL)

    Stable Food Crops Turning Into Commercial Crops: Case studies of Teff, Wheat and Rice in Ethiopia Imports are very crucial for the survival of a small open economy such as Ghana. In this paper, we estimate an import demand function for Ghana for the period 1970 to 2002, as well as consider the time series properties of ...

  18. marine survival ecosystem indicators - Estimating the ecosystem indicators of anadromous salmonids in the Puget Sound region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The objective of this project is to develop a simple approach for estimating the marine survival and causes of trends in survival. Data is a summary of ecosystem...

  19. [Estimating renal function with formulas

    NARCIS (Netherlands)

    Verhave, J.C.; Wetzels, J.F.M.; Bakker, S.J.; Gansevoort, R.T.

    2007-01-01

    A glomerular filtration rate (GFR) <60 ml/min/1.73 m2 is associated with an increased risk of cardiovascular disease and renal insufficiency. The formula of the 'Modification of diet in renal disease' (MDRD) study is derived from plasma-creatinine concentrations and estimates GFR based on age, sex

  20. Estimating progression-free survival in patients with glioblastoma using routinely collected data.

    Science.gov (United States)

    Kelly, Charlotte; Majewska, Paulina; Ioannidis, Stefanos; Raza, Muhammad Hasan; Williams, Matt

    2017-12-01

    Glioblastoma (GBM) represents 80% of all primary malignant brain tumours in adults. Prognosis is poor, and there is a clear correlation between disease progression and deterioration in functional status. In this pilot study we assess whether we can estimate disease progression and progression free survival (PFS) from routinely collected electronic healthcare data. We identified fifty patients with glioblastoma who had chemo-radiotherapy. For each patient we manually collected a reference data set recording demographics, surgery, radiotherapy, chemotherapy, follow-up and death. We also obtained an electronic routine data set for each patient by combining local data on chemotherapy/radiotherapy and hospital admissions. We calculated overall survival (OS) and PFS using the reference data set, and estimated them using the routine data sets using two different methods, and compared the estimated measures with the reference measures. Overall survival was 68% at 1 year and median OS was 12.8 months. The routine data correctly identified progressive disease in 37 of 40 patients and stable disease in 7 of 10 patients. PFS was 7.4 months and the estimated PFS using routine data was 9.1 and 7.8 months with methods 1 and 2 respectively. There was acceptable agreement between reference and routine data in 49 of 50 patients for OS and 35 of 50 patients for PFS. The event of progression, subsequent treatment and OS are well estimated using our approach, but PFS estimation is less accurate. Our approach could refine our understanding of the disease course and allow us to report PFS, OS and treatment nationally.

  1. Comparison of methods for estimating the attributable risk in the context of survival analysis

    Directory of Open Access Journals (Sweden)

    Malamine Gassama

    2017-01-01

    Full Text Available Abstract Background The attributable risk (AR measures the proportion of disease cases that can be attributed to an exposure in the population. Several definitions and estimation methods have been proposed for survival data. Methods Using simulations, we compared four methods for estimating AR defined in terms of survival functions: two nonparametric methods based on Kaplan-Meier’s estimator, one semiparametric based on Cox’s model, and one parametric based on the piecewise constant hazards model, as well as one simpler method based on estimated exposure prevalence at baseline and Cox’s model hazard ratio. We considered a fixed binary exposure with varying exposure probabilities and strengths of association, and generated event times from a proportional hazards model with constant or monotonic (decreasing or increasing Weibull baseline hazard, as well as from a nonproportional hazards model. We simulated 1,000 independent samples of size 1,000 or 10,000. The methods were compared in terms of mean bias, mean estimated standard error, empirical standard deviation and 95% confidence interval coverage probability at four equally spaced time points. Results Under proportional hazards, all five methods yielded unbiased results regardless of sample size. Nonparametric methods displayed greater variability than other approaches. All methods showed satisfactory coverage except for nonparametric methods at the end of follow-up for a sample size of 1,000 especially. With nonproportional hazards, nonparametric methods yielded similar results to those under proportional hazards, whereas semiparametric and parametric approaches that both relied on the proportional hazards assumption performed poorly. These methods were applied to estimate the AR of breast cancer due to menopausal hormone therapy in 38,359 women of the E3N cohort. Conclusion In practice, our study suggests to use the semiparametric or parametric approaches to estimate AR as a function of

  2. Comparison of methods for estimating the attributable risk in the context of survival analysis.

    Science.gov (United States)

    Gassama, Malamine; Bénichou, Jacques; Dartois, Laureen; Thiébaut, Anne C M

    2017-01-23

    The attributable risk (AR) measures the proportion of disease cases that can be attributed to an exposure in the population. Several definitions and estimation methods have been proposed for survival data. Using simulations, we compared four methods for estimating AR defined in terms of survival functions: two nonparametric methods based on Kaplan-Meier's estimator, one semiparametric based on Cox's model, and one parametric based on the piecewise constant hazards model, as well as one simpler method based on estimated exposure prevalence at baseline and Cox's model hazard ratio. We considered a fixed binary exposure with varying exposure probabilities and strengths of association, and generated event times from a proportional hazards model with constant or monotonic (decreasing or increasing) Weibull baseline hazard, as well as from a nonproportional hazards model. We simulated 1,000 independent samples of size 1,000 or 10,000. The methods were compared in terms of mean bias, mean estimated standard error, empirical standard deviation and 95% confidence interval coverage probability at four equally spaced time points. Under proportional hazards, all five methods yielded unbiased results regardless of sample size. Nonparametric methods displayed greater variability than other approaches. All methods showed satisfactory coverage except for nonparametric methods at the end of follow-up for a sample size of 1,000 especially. With nonproportional hazards, nonparametric methods yielded similar results to those under proportional hazards, whereas semiparametric and parametric approaches that both relied on the proportional hazards assumption performed poorly. These methods were applied to estimate the AR of breast cancer due to menopausal hormone therapy in 38,359 women of the E3N cohort. In practice, our study suggests to use the semiparametric or parametric approaches to estimate AR as a function of time in cohort studies if the proportional hazards assumption appears

  3. Estimating Stochastic Volatility Models using Prediction-based Estimating Functions

    DEFF Research Database (Denmark)

    Lunde, Asger; Brix, Anne Floor

    In this paper prediction-based estimating functions (PBEFs), introduced in Sørensen (2000), are reviewed and PBEFs for the Heston (1993) stochastic volatility model are derived. The finite sample performance of the PBEF based estimator is investigated in a Monte Carlo study, and compared...

  4. Semiparametric Methods to Contrast Gap Time Survival Functions: Application to Repeat Kidney Transplantation

    OpenAIRE

    Shu, Xu; Schaubel, Douglas E.

    2015-01-01

    Times between successive events (i.e., gap times) are of great importance in survival analysis. Although many methods exist for estimating covariate effects on gap times, very few existing methods allow for comparisons between gap times themselves. Motivated by the comparison of primary and repeat transplantation, our interest is specifically in contrasting the gap time survival functions and their integration (restricted mean gap time). Two major challenges in gap time analysis are non-ident...

  5. Hazard Function Estimation with Cause-of-Death Data Missing at Random

    OpenAIRE

    Wang, Qihua; Dinse, Gregg E.; Liu, Chunling

    2012-01-01

    Hazard function estimation is an important part of survival analysis. Interest often centers on estimating the hazard function associated with a particular cause of death. We propose three nonparametric kernel estimators for the hazard function, all of which are appropriate when death times are subject to random censorship and censoring indicators can be missing at random. Specifically, we present a regression surrogate estimator, an imputation estimator, and an inverse probability weighted e...

  6. Non-Parametric Estimation of Correlation Functions

    DEFF Research Database (Denmark)

    Brincker, Rune; Rytter, Anders; Krenk, Steen

    In this paper three methods of non-parametric correlation function estimation are reviewed and evaluated: the direct method, estimation by the Fast Fourier Transform and finally estimation by the Random Decrement technique. The basic ideas of the techniques are reviewed, sources of bias are point...... out, and methods to prevent bias are presented. The techniques are evaluated by comparing their speed and accuracy on the simple case of estimating auto-correlation functions for the response of a single degree-of-freedom system loaded with white noise....

  7. Diameter Growth, Survival, and Volume Estimates for Missouri Trees

    Science.gov (United States)

    Stephen R. Shifley; W. Brad Smith

    1982-01-01

    Measurements of more than 20,000 Missouri trees were summarized by species and diameter class into tables of mean annual diameter growth, annual probability of survival, net cubic foot volume, and net board foot volume. In the absence of better forecasting techniques, this information can be utilized to project short-term changes for Missouri trees, inventory plots,...

  8. Annual survival estimation of migratory songbirds confounded by incomplete breeding site-fidelity: study designs that may help

    Directory of Open Access Journals (Sweden)

    Marshall, M. R.

    2004-06-01

    surrounding areas to minimize bias. Therefore, as an alternative protocol, we analyzed the data with subsets of three progressively larger areas surrounding the core. The data subsets provided four estimates of apparent survival that asymptotically approached true survival. This study design and analytical approach is likely to be logistically feasible in field settings and yields estimates of true survival unbiased (bias < 0.03 by incomplete breeding site–fidelity over a range of inter–annual territory movement patterns. The third approach we investigated used a robust design data collection and analysis approach. This approach resulted in estimates of survival that were unbiased (bias < 0.02, but were very imprecise and likely would not yield reliable estimates in field situations. The fourth approach utilized a fixed study area size, but modeled detection probability as a function of bird proximity to the study plot boundary (e.g., those birds closest to the edge are more likely to emigrate. This approach also resulted in estimates of survival that were unbiased (bias < 0.02, but because the individual covariates were normalized, the average capture probability was 0.50, and thus did not provide an accurate estimate of the true capture probability. Our results show that the core–area with surrounding resight–only can provide estimates of survival that are not biased by the effects of incomplete breeding site–fidelity.

  9. Incorporating movement patterns to improve survival estimates for juvenile bull trout

    Science.gov (United States)

    Bowerman, Tracy; Budy, Phaedra

    2012-01-01

    Populations of many fish species are sensitive to changes in vital rates during early life stages, but our understanding of the factors affecting growth, survival, and movement patterns is often extremely limited for juvenile fish. These critical information gaps are particularly evident for bull trout Salvelinus confluentus, a threatened Pacific Northwest char. We combined several active and passive mark–recapture and resight techniques to assess migration rates and estimate survival for juvenile bull trout (70–170 mm total length). We evaluated the relative performance of multiple survival estimation techniques by comparing results from a common Cormack–Jolly–Seber (CJS) model, the less widely used Barker model, and a simple return rate (an index of survival). Juvenile bull trout of all sizes emigrated from their natal habitat throughout the year, and thereafter migrated up to 50 km downstream. With the CJS model, high emigration rates led to an extreme underestimate of apparent survival, a combined estimate of site fidelity and survival. In contrast, the Barker model, which allows survival and emigration to be modeled as separate parameters, produced estimates of survival that were much less biased than the return rate. Estimates of age-class-specific annual survival from the Barker model based on all available data were 0.218±0.028 (estimate±SE) for age-1 bull trout and 0.231±0.065 for age-2 bull trout. This research demonstrates the importance of incorporating movement patterns into survival analyses, and we provide one of the first field-based estimates of juvenile bull trout annual survival in relatively pristine rearing conditions. These estimates can provide a baseline for comparison with future studies in more impacted systems and will help managers develop reliable stage-structured population models to evaluate future recovery strategies.

  10. The Careers, Survival Functions and Income of Artists

    DEFF Research Database (Denmark)

    Bille, Trine; Jensen, Søren; Vestergaard, Trine

    , comparatively for different groups of artists, the factors that affect 1) the income of artists, and 2) the probability of an artist exits the artists labor market. The paper compares different groups of artists, by looking at income functions and survival functions concerning risks to exit the labor market...... have been based on interviews and this approach has of course its pros and cons. Very few studies are based on true longitudinal data making it possible to study artists income development and survival in the professions (one exception is Coulangeon et al., 2005) The aim of this study is to analyze...

  11. Bayesian Analysis of the Survival Function and Failure Rate of Weibull Distribution with Censored Data

    Directory of Open Access Journals (Sweden)

    Chris Bambey Guure

    2012-01-01

    Full Text Available The survival function of the Weibull distribution determines the probability that a unit or an individual will survive beyond a certain specified time while the failure rate is the rate at which a randomly selected individual known to be alive at time will die at time (. The classical approach for estimating the survival function and the failure rate is the maximum likelihood method. In this study, we strive to determine the best method, by comparing the classical maximum likelihood against the Bayesian estimators using an informative prior and a proposed data-dependent prior known as generalised noninformative prior. The Bayesian estimation is considered under three loss functions. Due to the complexity in dealing with the integrals using the Bayesian estimator, Lindley’s approximation procedure is employed to reduce the ratio of the integrals. For the purpose of comparison, the mean squared error (MSE and the absolute bias are obtained. This study is conducted via simulation by utilising different sample sizes. We observed from the study that the generalised prior we assumed performed better than the others under linear exponential loss function with respect to MSE and under general entropy loss function with respect to absolute bias.

  12. On conditional hazard function estimate for functional mixing data

    Directory of Open Access Journals (Sweden)

    abbes rabhi

    2015-02-01

    Full Text Available This paper considers the problem of nonparametric estimation of the conditional hazard function for functional mixing data. In particular, given a strictly stationary random variables $\\displaystyle Z_i=\\left(X_i,\\ Y_i\\right_{i\\in\\mathbb{N}}$, we investigate a kernel estimate of the conditional hazard function of univariate response variable $Y_i$ given the functional variable $X_i$. The mean squared convergence rate is given and the asymptotic normality of the proposed estimator is proven.

  13. Functional role of kallikrein 6 in regulating immune cell survival.

    Directory of Open Access Journals (Sweden)

    Isobel A Scarisbrick

    2011-03-01

    Full Text Available Kallikrein 6 (KLK6 is a newly identified member of the kallikrein family of secreted serine proteases that prior studies indicate is elevated at sites of central nervous system (CNS inflammation and which shows regulated expression with T cell activation. Notably, KLK6 is also elevated in the serum of multiple sclerosis (MS patients however its potential roles in immune function are unknown. Herein we specifically examine whether KLK6 alters immune cell survival and the possible mechanism by which this may occur.Using murine whole splenocyte preparations and the human Jurkat T cell line we demonstrate that KLK6 robustly supports cell survival across a range of cell death paradigms. Recombinant KLK6 was shown to significantly reduce cell death under resting conditions and in response to camptothecin, dexamethasone, staurosporine and Fas-ligand. Moreover, KLK6-over expression in Jurkat T cells was shown to generate parallel pro-survival effects. In mixed splenocyte populations the vigorous immune cell survival promoting effects of KLK6 were shown to include both T and B lymphocytes, to occur with as little as 5 minutes of treatment, and to involve up regulation of the pro-survival protein B-cell lymphoma-extra large (Bcl-XL, and inhibition of the pro-apoptotic protein Bcl-2-interacting mediator of cell death (Bim. The ability of KLK6 to promote survival of splenic T cells was also shown to be absent in cell preparations derived from PAR1 deficient mice.KLK6 promotes lymphocyte survival by a mechanism that depends in part on activation of PAR1. These findings point to a novel molecular mechanism regulating lymphocyte survival that is likely to have relevance to a range of immunological responses that depend on apoptosis for immune clearance and maintenance of homeostasis.

  14. Estimating state-contingent production functions

    DEFF Research Database (Denmark)

    Rasmussen, Svend; Karantininis, Kostas

    The paper reviews the empirical problem of estimating state-contingent production functions. The major problem is that states of nature may not be registered and/or that the number of observation per state is low. Monte Carlo simulation is used to generate an artificial, uncertain production...... environment based on Cobb Douglas production functions with state-contingent parameters. The pa-rameters are subsequently estimated based on different sizes of samples using Generalized Least Squares and Generalized Maximum Entropy and the results are compared. It is concluded that Maximum Entropy may...... be useful, but that further analysis is needed to evaluate the efficiency of this estimation method compared to traditional methods....

  15. On Optimal Projective Fusers for Function Estimators

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N.S.V.

    1999-06-22

    We propose a fuser that projects different function estimators in different regions of the input space based on the lower envelope of the error curves of the individual estimators. This fuser is shown to be optimal among projective fusers and also to perform at least as well as the best individual estimator. By incorporating an optimal linear fuser as another estimator, this fuser performs at least as well as the optimal linear combination. We illustrate the fuser by combining neural networks trained using different parameters for the network and/or for learning algorithms.

  16. Up-to-date and precise estimates of cancer patient survival: model-based period analysis.

    Science.gov (United States)

    Brenner, Hermann; Hakulinen, Timo

    2006-10-01

    Monitoring of progress in cancer patient survival by cancer registries should be as up-to-date as possible. Period analysis has been shown to provide more up-to-date survival estimates than do traditional methods of survival analysis. However, there is a trade-off between up-to-dateness and the precision of period estimates, in that increasing the up-to-dateness of survival estimates by restricting the analysis to a relatively short, recent time period, such as the most recent calendar year for which cancer registry data are available, goes along with a loss of precision. The authors propose a model-based approach to maximize the up-to-dateness of period estimates at minimal loss of precision. The approach is illustrated for monitoring of 5-year relative survival of patients diagnosed with one of 20 common forms of cancer in Finland between 1953 and 2002 by use of data from the nationwide Finnish Cancer Registry. It is shown that the model-based approach provides survival estimates that are as up-to-date as the most up-to-date conventional period estimates and at the same time much more precise than the latter. The modeling approach may further enhance the use of period analysis for deriving up-to-date cancer survival rates.

  17. DTR: An R Package for Estimation and Comparison of Survival Outcomes of Dynamic Treatment

    Directory of Open Access Journals (Sweden)

    Xinyu Tang

    2015-06-01

    Full Text Available Sequentially randomized designs, more recently known as sequential multiple assignment randomized trial (SMART designs, are widely used in biomedical research, particularly in clinical trials, to assess and compare the effects of various treatment sequences. In such designs, patients are initially randomized to one of the rst-stage therapies. Then patients meeting some criteria (e.g., no relapse of disease participate in the second-stage randomization to one of the second-stage therapies. The advantage of such a design is that it allows the investigator to study various treatment sequences where the patients' second-stage therapies can be adjusted based on their responses to the rst-stage therapies. In the past few years, substantial improvement has been made in the statistical methods for analyzing the data from SMARTs. Much of the proposed statistical approaches focus on estimating and comparing the survival outcomes of treatment sequences embedded in the SMART designs. In this article, we introduce the R package DTR, which provides a set of functions that can be used to estimate and compare the effects of different treatment sequences on survival outcomes using the newly proposed statistical approaches. The proposed package is also illustrated using simulated data from SMARTs.

  18. Re-evaluating neonatal-age models for ungulates: does model choice affect survival estimates?

    Directory of Open Access Journals (Sweden)

    Troy W Grovenburg

    Full Text Available New-hoof growth is regarded as the most reliable metric for predicting age of newborn ungulates, but variation in estimated age among hoof-growth equations that have been developed may affect estimates of survival in staggered-entry models. We used known-age newborns to evaluate variation in age estimates among existing hoof-growth equations and to determine the consequences of that variation on survival estimates. During 2001-2009, we captured and radiocollared 174 newborn (≤24-hrs old ungulates: 76 white-tailed deer (Odocoileus virginianus in Minnesota and South Dakota, 61 mule deer (O. hemionus in California, and 37 pronghorn (Antilocapra americana in South Dakota. Estimated age of known-age newborns differed among hoof-growth models and varied by >15 days for white-tailed deer, >20 days for mule deer, and >10 days for pronghorn. Accuracy (i.e., the proportion of neonates assigned to the correct age in aging newborns using published equations ranged from 0.0% to 39.4% in white-tailed deer, 0.0% to 3.3% in mule deer, and was 0.0% for pronghorns. Results of survival modeling indicated that variability in estimates of age-at-capture affected short-term estimates of survival (i.e., 30 days for white-tailed deer and mule deer, and survival estimates over a longer time frame (i.e., 120 days for mule deer. Conversely, survival estimates for pronghorn were not affected by estimates of age. Our analyses indicate that modeling survival in daily intervals is too fine a temporal scale when age-at-capture is unknown given the potential inaccuracies among equations used to estimate age of neonates. Instead, weekly survival intervals are more appropriate because most models accurately predicted ages within 1 week of the known age. Variation among results of neonatal-age models on short- and long-term estimates of survival for known-age young emphasizes the importance of selecting an appropriate hoof-growth equation and appropriately defining intervals (i

  19. ESTIMATION OF FUNCTIONALS OF SPARSE COVARIANCE MATRICES.

    Science.gov (United States)

    Fan, Jianqing; Rigollet, Philippe; Wang, Weichen

    High-dimensional statistical tests often ignore correlations to gain simplicity and stability leading to null distributions that depend on functionals of correlation matrices such as their Frobenius norm and other ℓ r norms. Motivated by the computation of critical values of such tests, we investigate the difficulty of estimation the functionals of sparse correlation matrices. Specifically, we show that simple plug-in procedures based on thresholded estimators of correlation matrices are sparsity-adaptive and minimax optimal over a large class of correlation matrices. Akin to previous results on functional estimation, the minimax rates exhibit an elbow phenomenon. Our results are further illustrated in simulated data as well as an empirical study of data arising in financial econometrics.

  20. Efficient Estimating Functions for Stochastic Differential Equations

    DEFF Research Database (Denmark)

    Jakobsen, Nina Munkholt

    The overall topic of this thesis is approximate martingale estimating function-based estimationfor solutions of stochastic differential equations, sampled at high frequency. Focuslies on the asymptotic properties of the estimators. The first part of the thesis deals with diffusions observed over...... of an effcient and an ineffcientestimator are compared graphically. The second part of the thesis concerns diffusions withfinite-activity jumps, observed over an increasing interval with terminal sampling time goingto infinity. Asymptotic distribution results are derived for consistent estimators of ageneral...

  1. Delay estimation for CMOS functional cells

    DEFF Research Database (Denmark)

    Madsen, Jan

    1991-01-01

    Presents a new RC tree network model for delay estimation of CMOS functional cells. The model is able to reflect topological changes within a cell, which is of particular interest when doing performance driven layout synthesis. Further, a set of algorithms to perform worst case analysis on arbitr...... on arbitrary CMOS functional cells using the proposed delay model, is presented. Both model and algorithms have been implemented as a part of a cell compiler (CELLO) working in an experimental silicon compiler environment....

  2. Estimating a Demand Function for Poultry Litter

    OpenAIRE

    Carreira, Rita I.; Goodwin, Harold L., Jr.

    2006-01-01

    Excess poultry litter could be a sustainable source of crop nutrients outside of nutrient-saturated regions if crop farmers are willing to utilize it. Using nearly 150 observations of actual poultry litter purchases in Oklahoma, Arkansas, and Missouri we estimate a demand function for poultry litter produced in northwest Arkansas.

  3. Estimates of annual survival probabilities for adult Florida manatees (Trichechus manatus latirostris)

    Science.gov (United States)

    Langtimm, C.A.; O'Shea, T.J.; Pradel, R.; Beck, C.A.

    1998-01-01

    The population dynamics of large, long-lived mammals are particularly sensitive to changes in adult survival. Understanding factors affecting survival patterns is therefore critical for developing and testing theories of population dynamics and for developing management strategies aimed at preventing declines or extinction in such taxa. Few studies have used modern analytical approaches for analyzing variation and testing hypotheses about survival probabilities in large mammals. This paper reports a detailed analysis of annual adult survival in the Florida manatee (Trichechus manatus latirostris), an endangered marine mammal, based on a mark-recapture approach. Natural and boat-inflicted scars distinctively 'marked' individual manatees that were cataloged in a computer-based photographic system. Photo-documented resightings provided 'recaptures.' Using open population models, annual adult-survival probabilities were estimated for manatees observed in winter in three areas of Florida: Blue Spring, Crystal River, and the Atlantic coast. After using goodness-of-fit tests in Program RELEASE to search for violations of the assumptions of mark-recapture analysis, survival and sighting probabilities were modeled under several different biological hypotheses with Program SURGE. Estimates of mean annual probability of sighting varied from 0.948 for Blue Spring to 0.737 for Crystal River and 0.507 for the Atlantic coast. At Crystal River and Blue Spring, annual survival probabilities were best estimated as constant over the study period at 0.96 (95% CI = 0.951-0.975 and 0.900-0.985, respectively). On the Atlantic coast, where manatees are impacted more by human activities, annual survival probabilities had a significantly lower mean estimate of 0.91 (95% CI = 0.887-0.926) and varied unpredictably over the study period. For each study area, survival did not differ between sexes and was independent of relative adult age. The high constant adult-survival probabilities estimated

  4. Semiparametric maximum likelihood estimation in normal transformation models for bivariate survival data

    OpenAIRE

    Yi Li; Ross L. Prentice; Xihong Lin

    2008-01-01

    We consider a class of semiparametric normal transformation models for right-censored bivariate failure times. Nonparametric hazard rate models are transformed to a standard normal model and a joint normal distribution is assumed for the bivariate vector of transformed variates. A semiparametric maximum likelihood estimation procedure is developed for estimating the marginal survival distribution and the pairwise correlation parameters. This produces an efficient estimator of the correlation ...

  5. The performance of different propensity score methods for estimating absolute effects of treatments on survival outcomes: A simulation study.

    Science.gov (United States)

    Austin, Peter C; Schuster, Tibor

    2016-10-01

    Observational studies are increasingly being used to estimate the effect of treatments, interventions and exposures on outcomes that can occur over time. Historically, the hazard ratio, which is a relative measure of effect, has been reported. However, medical decision making is best informed when both relative and absolute measures of effect are reported. When outcomes are time-to-event in nature, the effect of treatment can also be quantified as the change in mean or median survival time due to treatment and the absolute reduction in the probability of the occurrence of an event within a specified duration of follow-up. We describe how three different propensity score methods, propensity score matching, stratification on the propensity score and inverse probability of treatment weighting using the propensity score, can be used to estimate absolute measures of treatment effect on survival outcomes. These methods are all based on estimating marginal survival functions under treatment and lack of treatment. We then conducted an extensive series of Monte Carlo simulations to compare the relative performance of these methods for estimating the absolute effects of treatment on survival outcomes. We found that stratification on the propensity score resulted in the greatest bias. Caliper matching on the propensity score and a method based on earlier work by Cole and Hernán tended to have the best performance for estimating absolute effects of treatment on survival outcomes. When the prevalence of treatment was less extreme, then inverse probability of treatment weighting-based methods tended to perform better than matching-based methods. © The Author(s) 2014.

  6. Symbiotic Dinoflagellate Functional Diversity Mediates Coral Survival under Ecological Crisis.

    Science.gov (United States)

    Suggett, David J; Warner, Mark E; Leggat, William

    2017-10-01

    Coral reefs have entered an era of 'ecological crisis' as climate change drives catastrophic reef loss worldwide. Coral growth and stress susceptibility are regulated by their endosymbiotic dinoflagellates (genus Symbiodinium). The phylogenetic diversity of Symbiodinium frequently corresponds to patterns of coral health and survival, but knowledge of functional diversity is ultimately necessary to reconcile broader ecological success over space and time. We explore here functional traits underpinning the complex biology of Symbiodinium that spans free-living algae to coral endosymbionts. In doing so we propose a mechanistic framework integrating the primary traits of resource acquisition and utilisation as a means to explain Symbiodinium functional diversity and to resolve the role of Symbiodinium in driving the stability of coral reefs under an uncertain future. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Induction of Protective Genes Leads to Islet Survival and Function

    Directory of Open Access Journals (Sweden)

    Hongjun Wang

    2011-01-01

    Full Text Available Islet transplantation is the most valid approach to the treatment of type 1 diabetes. However, the function of transplanted islets is often compromised since a large number of β cells undergo apoptosis induced by stress and the immune rejection response elicited by the recipient after transplantation. Conventional treatment for islet transplantation is to administer immunosuppressive drugs to the recipient to suppress the immune rejection response mounted against transplanted islets. Induction of protective genes in the recipient (e.g., heme oxygenase-1 (HO-1, A20/tumor necrosis factor alpha inducible protein3 (tnfaip3, biliverdin reductase (BVR, Bcl2, and others or administration of one or more of the products of HO-1 to the donor, the islets themselves, and/or the recipient offers an alternative or synergistic approach to improve islet graft survival and function. In this perspective, we summarize studies describing the protective effects of these genes on islet survival and function in rodent allogeneic and xenogeneic transplantation models and the prevention of onset of diabetes, with emphasis on HO-1, A20, and BVR. Such approaches are also appealing to islet autotransplantation in patients with chronic pancreatitis after total pancreatectomy, a procedure that currently only leads to 1/3 of transplanted patients being diabetes-free.

  8. [Functional limitation and survival of community dwelling elderly].

    Science.gov (United States)

    Maciel, Alvaro Campos Cavalcanti; Guerra, Ricardo Oliveira

    2008-01-01

    The present study aims to analyze the functional limitation as risk factor of death of elderly dwelling in a community and its relationship with socio-demographic, physical health and neuropsychiatric related factors. A prospective study was carried out in the city of Santa Cruz, Rio Grande do Norte, Brasil. A total of 310 randomly selected elderly formed the baseline (63.5% women, 73.7+/-9.03 years). The Katz Index was used to evaluate the functional capacity for basic activities of daily living. The follow-up period was of 53 months. The statistical methods used were bivariate analysis (Pearson's chi-square), survival analysis by the Kaplan-Meyer method, followed by Cox regression in multivariate analysis, with the respective hazards ratios (HR). A total of 60 elderly (20.5%) died during the study follow-up; the main cause of death was cardiovascular disease. The mean survival time was of about 24.8 months, and the main risk factors identified at Cox regression were cognitive deficit (HR= 4.30) and stroke (HR= 3.49) besides the dependence for the basic activities of daily living (HR = 3.17). The functional limitation was an independent risk factor for death.

  9. Effect of somatic cell count level on functional longevity in Valle del Belice dairy sheep assessed using survival analysis

    NARCIS (Netherlands)

    Riggio, V.; Maizon, D.O.; Portolano, B.; Bovenhuis, H.; Arendonk, van J.A.M.

    2009-01-01

    The objectives of this study were to evaluate the effect of somatic cell count (SCC) on functional longevity and to estimate the heritability of functional longevity using survival analysis in Valle del Belice dairy sheep. A total of 4,880 lactations of 2,190 ewes from 11 flocks were used. In this

  10. Estimating the personal cure rate of cancer patients using population-based grouped cancer survival data.

    Science.gov (United States)

    Binbing Yu; Tiwari, Ram C; Feuer, Eric J

    2011-06-01

    Cancer patients are subject to multiple competing risks of death and may die from causes other than the cancer diagnosed. The probability of not dying from the cancer diagnosed, which is one of the patients' main concerns, is sometimes called the 'personal cure' rate. Two approaches of modelling competing-risk survival data, namely the cause-specific hazards approach and the mixture model approach, have been used to model competing-risk survival data. In this article, we first show the connection and differences between crude cause-specific survival in the presence of other causes and net survival in the absence of other causes. The mixture survival model is extended to population-based grouped survival data to estimate the personal cure rate. Using the colorectal cancer survival data from the Surveillance, Epidemiology and End Results Programme, we estimate the probabilities of dying from colorectal cancer, heart disease, and other causes by age at diagnosis, race and American Joint Committee on Cancer stage.

  11. How the importance of survival estimates in estimating Whinchat population dynamics depends on the scale of migratory connectivity and site fidelity

    OpenAIRE

    Cresswell, Will

    2015-01-01

    Accurate monitoring of whinchat population dynamics requires accurate estimates of breeding season survival and productivity, non-breeding survival and site fidelity (dispersal, immigration and emmigration). But monitoring of non-breeding survival between breeding seasons is confounded by the scale of site fidelity resulting in low estimates, and this will vary dependent on breeding success. Only one study (in progress) has measured true survival of whinchats on the wintering grounds (in Nige...

  12. Hazard Function Estimation with Cause-of-Death Data Missing at Random.

    Science.gov (United States)

    Wang, Qihua; Dinse, Gregg E; Liu, Chunling

    2012-04-01

    Hazard function estimation is an important part of survival analysis. Interest often centers on estimating the hazard function associated with a particular cause of death. We propose three nonparametric kernel estimators for the hazard function, all of which are appropriate when death times are subject to random censorship and censoring indicators can be missing at random. Specifically, we present a regression surrogate estimator, an imputation estimator, and an inverse probability weighted estimator. All three estimators are uniformly strongly consistent and asymptotically normal. We derive asymptotic representations of the mean squared error and the mean integrated squared error for these estimators and we discuss a data-driven bandwidth selection method. A simulation study, conducted to assess finite sample behavior, demonstrates that the proposed hazard estimators perform relatively well. We illustrate our methods with an analysis of some vascular disease data.

  13. Extension of cox proportional hazard model for estimation of interrelated age-period-cohort effects on cancer survival.

    Science.gov (United States)

    Mdzinarishvili, Tengiz; Gleason, Michael X; Kinarsky, Leo; Sherman, Simon

    2011-02-23

    In the frame of the Cox proportional hazard (PH) model, a novel two-step procedure for estimating age-period-cohort (APC) effects on the hazard function of death from cancer was developed. In the first step, the procedure estimates the influence of joint APC effects on the hazard function, using Cox PH regression procedures from a standard software package. In the second step, the coefficients for age at diagnosis, time period and birth cohort effects are estimated. To solve the identifiability problem that arises in estimating these coefficients, an assumption that neighboring birth cohorts almost equally affect the hazard function was utilized. Using an anchoring technique, simple procedures for obtaining estimates of interrelated age at diagnosis, time period and birth cohort effect coefficients were developed.As a proof-of-concept these procedures were used to analyze survival data, collected in the SEER database, on white men and women diagnosed with LC in 1975-1999 and the age at diagnosis, time period and birth cohort effect coefficients were estimated. The PH assumption was evaluated by a graphical approach using log-log plots. Analysis of trends of these coefficients suggests that the hazard of death from LC for a given time from cancer diagnosis: (i) decreases between 1975 and 1999; (ii) increases with increasing the age at diagnosis; and (iii) depends upon birth cohort effects.The proposed computing procedure can be used for estimating joint APC effects, as well as interrelated age at diagnosis, time period and birth cohort effects in survival analysis of different types of cancer.

  14. Camera trapping estimates of density and survival of fishers (Martes pennanti)

    Science.gov (United States)

    Mark J. Jordan; Reginald H. Barrett; Kathryn L. Purcell

    2011-01-01

    Developing efficient monitoring strategies for species of conservation concern is critical to ensuring their persistence. We have developed a method using camera traps to estimate density and survival in mesocarnivores and tested it on a population of fishers Martes pennanti in an area of approximately 300 km2 of the southern...

  15. Survival estimates of wild and captive-bred released Puaiohi, an endangered Hawaiian thrush

    Science.gov (United States)

    VanderWerf, Eric; Crampton, Lisa H.; Diegmann, Julia; Atkinson, Carter T.; Leonard, David L.

    2014-01-01

    Estimating and monitoring adult and juvenile survival are vital to understanding population status, informing recovery planning for endangered species, and quantifying the success of management. We used mark–recapture models to estimate apparent annual survival of the Puaiohi (Myadestes palmeri), an endangered thrush endemic to the Hawaiian island of Kauai, from 2005 to 2011. Our sample included 87 wild birds and 123 captive-bred birds that were released at various ages. Survival was higher for wild adult males (0.71 ± 0.09) than for wild adult females (0.46 ± 0.12). Survival of wild juveniles (0.23 ± 0.06) was lower than that of wild adults of both sexes, indicating that recruitment may limit population growth. Captive-bred birds released when survival (0.26 ± 0.21) comparable with that of wild juveniles, but captive-bred birds released at 1–3 yr old had very low survival (0.05 ± 0.06). Only 8 of 123 (7%) captive birds were seen again after release. Two wild birds resighted five years after marking are the oldest known individuals, being at least six years of age. Malarial infection did not affect survival of wild Puaiohi, unlike many Hawaiian forest birds. The difference between adult male and adult female survival is consistent with rat (Rattusspp.) predation of females on the nest as a major source of mortality. As such, attempting to reduce nest predation by controlling rats may be the best available management option. Releasing captive-bred birds has had little effect on the wild population in recent years.

  16. Assessment of lead-time bias in estimates of relative survival for breast cancer.

    Science.gov (United States)

    Andersson, Therese M-L; Rutherford, Mark J; Humphreys, Keith

    2017-02-01

    Relative survival ratios (RSRs) can be useful for evaluating the impact of changes in cancer care on the prognosis of cancer patients or for comparing the prognosis for different subgroups of patients, but their use is problematic for cancer sites where screening has been introduced due to the potential of lead-time bias. Lead-time is survival time that is added to a patient's survival time because of an earlier diagnosis irrespective of a possibly postponed time of death. In the presence of screening it is difficult to disentangle how much of an observed improvement in survival is real and how much is due to lead-time bias. Even so, RSRs are often presented for breast cancer, a site where screening has led to early diagnosis, with the assumption that the lead-time bias is small. We describe a simulation-based framework for studying the lead-time bias due to mammography screening on RSRs of breast cancer based on a natural history model developed in a Swedish setting. We have performed simulations, using this framework, under different assumptions for screening sensitivity and breast cancer survival with the aim of estimating the lead-time bias. Screening every second year among ages 40-75 was introduced assuming that screening had no effect on survival, except for lead-time bias. Relative survival was estimated both with and without screening to enable quantification of the lead-time bias. Scenarios with low, moderate and high breast cancer survival, and low, moderate and high screening sensitivity were simulated, and the lead-time bias assessed in all scenarios. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Postoperative Respiratory Function and Survival After Pneumonectomy in Dogs and Cats.

    Science.gov (United States)

    Majeski, Stephanie A; Steffey, Michele A; Mayhew, Philipp D; Hunt, Geraldine B; Holt, David E; Runge, Jeffrey J; Kass, Philip H; Mellema, Matthew

    2016-08-01

    To describe indications for, and outcomes after, pneumonectomy in dogs and cats, including assessment of immediate postoperative respiratory function in comparison to dogs undergoing single lung lobectomy. Retrospective case series. Dogs (n=16) and cats (n=7) with naturally occurring pulmonary disease. Medical records (1990-2014) of dogs and cats undergoing right or left pneumonectomy were reviewed. Data retrieved included signalment, history, preoperative diagnostics, operative descriptions, postoperative data including respiratory function, and postdischarge outcomes. For respiratory function comparisons, medical records of dogs having undergone a single lung lobectomy via median sternotomy (n=15) or intercostal thoracotomy (n=15) were reviewed. Twenty-three cases (16 dogs, 7 cats) were included. Pneumonectomy was performed for congenital (1 dog, 1 cat), neoplastic (8 dogs, 1 cat), and infectious (7 dogs, 5 cats) disease. Postoperative aspiration pneumonia occurred in 2 dogs; 15 of 16 dogs (94%) and 6/7 cats (86%) survived to hospital discharge. After pneumonectomy, dogs had a significantly higher postoperative PaO2 on 21% oxygen (P=.033) and lower postoperative A-a gradient (P=.004) compared to dogs undergoing single lung lobectomy. Survival times (right-censored at last follow-up) for dogs ranged from 2 days to 7 years (estimated median=1,868 days) and for cats from 1-585 days. Dogs and cats have acceptable respiratory function immediately postoperatively and most have protracted long-term survival after pneumonectomy for a variety of pulmonary diseases. © Copyright 2016 by The American College of Veterinary Surgeons.

  18. Survival and function of phagocytes in blood culture media

    DEFF Research Database (Denmark)

    Fischer, T K; Prag, J; Kharazmi, A

    1999-01-01

    The survival and function of human phagocytes in sterile aerobic and anaerobic blood culture media were investigated using neutrophil morphology, white blood cell count in a haemoanalyser, flow cytometry, oxidative burst response, and bactericidal effect in Colorbact and Septi-Chek blood culture...... media and Bact/Alert. When comparing agitation to stationary incubation no difference in phagocytic activity was found. The methods showed the same trends demonstrating that the phagocytes' viability and activity were prolonged by oxygen and shortened by anaerobic conditions and sodium polyethanol...... sulfonate (SPS). Best preserved activity and viability were found in the aerobic media containing less than 0.5 g/l SPS, in which significant phagocyte oxidative burst and bactericidal activity were found up to 4 days after inoculation. Considering that the majority of bacteremias are due to aerobic...

  19. Myocardial contractile function in survived neonatal piglets after cardiopulmonary bypass

    Directory of Open Access Journals (Sweden)

    Popov Aron-Frederik

    2010-11-01

    Full Text Available Abstract Background Hemodynamic function may be depressed in the early postoperative stages after cardiac surgery. The aim of this study was the analysis of the myocardial contractility in neonates after cardiopulmonary bypass (CPB and mild hypothermia. Methods Three indices of left ventricular myocardial contractile function (dP/dt, (dP/dt/P, and wall thickening were studied up to 6 hours after CPB in neonatal piglets (CPB group; n = 4. The contractility data were analysed and then compared to the data of newborn piglets who also underwent median thoracotomy and instrumentation for the same time intervals but without CPB (non-CPB group; n = 3. Results Left ventricular dP/dtmax and (dP/dtmax/P remained stable in CPB group, while dP/dtmax decreased in non-CPB group 5 hours postoperatively (1761 ± 205 mmHg/s at baseline vs. 1170 ± 205 mmHg/s after 5 h; p max and (dP/dtmax/P there were no statistically significant differences between the two groups. Comparably, although myocardial thickening decreased in the non-CPB group the differences between the two groups were not statistically significant. Conclusions The myocardial contractile function in survived neonatal piglets remained stable 6 hours after cardiopulmonary bypass and mild hypothermia probably due to regional hypercontractility.

  20. Cure fraction estimation from the mixture cure models for grouped survival data.

    Science.gov (United States)

    Yu, Binbing; Tiwari, Ram C; Cronin, Kathleen A; Feuer, Eric J

    2004-06-15

    Mixture cure models are usually used to model failure time data with long-term survivors. These models have been applied to grouped survival data. The models provide simultaneous estimates of the proportion of the patients cured from disease and the distribution of the survival times for uncured patients (latency distribution). However, a crucial issue with mixture cure models is the identifiability of the cure fraction and parameters of kernel distribution. Cure fraction estimates can be quite sensitive to the choice of latency distributions and length of follow-up time. In this paper, sensitivity of parameter estimates under semi-parametric model and several most commonly used parametric models, namely lognormal, loglogistic, Weibull and generalized Gamma distributions, is explored. The cure fraction estimates from the model with generalized Gamma distribution is found to be quite robust. A simulation study was carried out to examine the effect of follow-up time and latency distribution specification on cure fraction estimation. The cure models with generalized Gamma latency distribution are applied to the population-based survival data for several cancer sites from the Surveillance, Epidemiology and End Results (SEER) Program. Several cautions on the general use of cure model are advised. Copyright 2004 John Wiley & Sons, Ltd.

  1. The Breslow estimator of the nonparametric baseline survivor function in Cox's regression model: some heuristics.

    Science.gov (United States)

    Hanley, James A

    2008-01-01

    Most survival analysis textbooks explain how the hazard ratio parameters in Cox's life table regression model are estimated. Fewer explain how the components of the nonparametric baseline survivor function are derived. Those that do often relegate the explanation to an "advanced" section and merely present the components as algebraic or iterative solutions to estimating equations. None comment on the structure of these estimators. This note brings out a heuristic representation that may help to de-mystify the structure.

  2. Survival

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These data provide information on the survival of California red-legged frogs in a unique ecosystem to better conserve this threatened species while restoring...

  3. Estimating long-term survival temperatures at the assemblage level in the marine environment: towards macrophysiology.

    Directory of Open Access Journals (Sweden)

    Joëlle Richard

    Full Text Available Defining ecologically relevant upper temperature limits of species is important in the context of environmental change. The approach used in the present paper estimates the relationship between rates of temperature change and upper temperature limits for survival in order to evaluate the maximum long-term survival temperature (Ts. This new approach integrates both the exposure time and the exposure temperature in the evaluation of temperature limits. Using data previously published for different temperate and Antarctic marine environments, we calculated Ts in each environment, which allowed us to calculate a new index: the Warming Allowance (WA. This index is defined as the maximum environmental temperature increase which an ectotherm in a given environment can tolerate, possibly with a decrease in performance but without endangering survival over seasonal or lifetime time-scales. It is calculated as the difference between maximum long-term survival temperature (Ts and mean maximum habitat temperature. It provides a measure of how close a species, assemblage or fauna are living to their temperature limits for long-term survival and hence their vulnerability to environmental warming. In contrast to data for terrestrial environments showing that warming tolerance increases with latitude, results here for marine environments show a less clear pattern as the smallest WA value was for the Peru upwelling system. The method applied here, relating upper temperature limits to rate of experimental warming, has potential for wide application in the identification of faunas with little capacity to survive environmental warming.

  4. Inferring population trends for the world's largest fish from mark-recapture estimates of survival.

    Science.gov (United States)

    Bradshaw, Corey J A; Mollet, Henry F; Meekan, Mark G

    2007-05-01

    1. Precise estimates of demographic rates are key components of population models used to predict the effects of stochastic environmental processes, harvest scenarios and extinction probability. 2. We used a 12-year photographic identification library of whale sharks from Ningaloo Reef, Western Australia to construct Cormack-Jolly-Seber (CJS) model estimates of survival within a capture-mark-recapture (CMR) framework. Estimated survival rates, population structure and assumptions regarding age at maturity, longevity and reproduction frequency were combined in a series of age-classified Leslie matrices to infer the potential trajectory of the population. 3. Using data from 111 individuals, there was evidence for time variation in apparent survival (phi) and recapture probability (p). The null model gave a phi of 0.825 (95% CI: 0.727-0.893) and p = 0.184 (95% CI: 0.121-0.271). The model-averaged annual phi ranged from 0.737 to 0.890. There was little evidence for a sex effect on survival. 4. Using standardized total length as a covariate in the CMR models indicated a size bias in phi. Ignoring the effects of time, a 5-m shark has a phi = 0.59 and a 9 m shark has phi = 0.81. 5. Of the 16 model combinations considered, 10 (63%) indicated a decreasing population (lambda sharks is declining, although more reproductive data are clearly needed to confirm this conclusion. Combining relatively precise survival estimates from CMR studies with realistic assumptions of other vital rates provides a useful heuristic framework for determining the vulnerability of large oceanic predators for which few direct data exist.

  5. Designing a monitoring program to estimate estuarine survival of anadromous salmon smolts: simulating the effect of sample design on inference

    Science.gov (United States)

    Romer, Jeremy D.; Gitelman, Alix I.; Clements, Shaun; Schreck, Carl B.

    2015-01-01

    A number of researchers have attempted to estimate salmonid smolt survival during outmigration through an estuary. However, it is currently unclear how the design of such studies influences the accuracy and precision of survival estimates. In this simulation study we consider four patterns of smolt survival probability in the estuary, and test the performance of several different sampling strategies for estimating estuarine survival assuming perfect detection. The four survival probability patterns each incorporate a systematic component (constant, linearly increasing, increasing and then decreasing, and two pulses) and a random component to reflect daily fluctuations in survival probability. Generally, spreading sampling effort (tagging) across the season resulted in more accurate estimates of survival. All sampling designs in this simulation tended to under-estimate the variation in the survival estimates because seasonal and daily variation in survival probability are not incorporated in the estimation procedure. This under-estimation results in poorer performance of estimates from larger samples. Thus, tagging more fish may not result in better estimates of survival if important components of variation are not accounted for. The results of our simulation incorporate survival probabilities and run distribution data from previous studies to help illustrate the tradeoffs among sampling strategies in terms of the number of tags needed and distribution of tagging effort. This information will assist researchers in developing improved monitoring programs and encourage discussion regarding issues that should be addressed prior to implementation of any telemetry-based monitoring plan. We believe implementation of an effective estuary survival monitoring program will strengthen the robustness of life cycle models used in recovery plans by providing missing data on where and how much mortality occurs in the riverine and estuarine portions of smolt migration. These data

  6. Apparent annual survival estimates of tropical songbirds better reflect life history variation when based on intensive field methods

    Science.gov (United States)

    Martin, Thomas E.; Riordan, Margaret M.; Repin, Rimi; Mouton, James C.; Blake, William M.

    2017-01-01

    AimAdult survival is central to theories explaining latitudinal gradients in life history strategies. Life history theory predicts higher adult survival in tropical than north temperate regions given lower fecundity and parental effort. Early studies were consistent with this prediction, but standard-effort netting studies in recent decades suggested that apparent survival rates in temperate and tropical regions strongly overlap. Such results do not fit with life history theory. Targeted marking and resighting of breeding adults yielded higher survival estimates in the tropics, but this approach is thought to overestimate survival because it does not sample social and age classes with lower survival. We compared the effect of field methods on tropical survival estimates and their relationships with life history traits.LocationSabah, Malaysian Borneo.Time period2008–2016.Major taxonPasseriformes.MethodsWe used standard-effort netting and resighted individuals of all social and age classes of 18 tropical songbird species over 8 years. We compared apparent survival estimates between these two field methods with differing analytical approaches.ResultsEstimated detection and apparent survival probabilities from standard-effort netting were similar to those from other tropical studies that used standard-effort netting. Resighting data verified that a high proportion of individuals that were never recaptured in standard-effort netting remained in the study area, and many were observed breeding. Across all analytical approaches, addition of resighting yielded substantially higher survival estimates than did standard-effort netting alone. These apparent survival estimates were higher than for temperate zone species, consistent with latitudinal differences in life histories. Moreover, apparent survival estimates from addition of resighting, but not from standard-effort netting alone, were correlated with parental effort as measured by egg temperature across species

  7. Sex ratio estimation and survival analysis for Orthetrum coerulescens (Odonata, Libellulidae)

    Science.gov (United States)

    Kery, M.; Juillerat, L.

    2004-01-01

    There is controversy over whether uneven sex ratios observed in mature dragonfly populations are a mere artifact resulting from the higher observability of males. Previous studies have at best made indirect inference about sex ratios by analysis of survival or recapture rates. Here, we obtain direct estimates of sex ratio from capture?recapture data based on the Cormack?Jolly?Seber model. We studied Orthetrum coerulescens (Fabricius, 1798) at three sites in the Swiss Jura Mountains over an entire activity period. Recapture rates per 5-day interval were 3.5 times greater for males (0.67, SE 0.02) than for females (0.19, SE 0.02). At two sites, recapture rate increased over the season for males and was constant for females, and at one site it decreased with precipitation for both sexes. In addition, recapture rate was higher with higher temperature for males only. We found no evidence for higher male survival rates in any population. Survival per 5-day interval for both sexes was estimated to be 0.77 (95% CI 0.75?0.79) without significant site or time-specific variation. There were clear effects of temperature (positive) and precipitation (negative) on survival rate at two sites. Direct estimates of sex ratios were not significantly different from 1 for any time interval. Hence, the observed male-biased sex ratio in adult O. coerulescens was an artifact resulting from the better observability of males. The method presented in this paper is applicable to sex ratio estimation in any kind of animal.

  8. Biochemical Control With Radiotherapy Improves Overall Survival in Intermediate and High-Risk Prostate Cancer Patients Who Have an Estimated 10-Year Overall Survival of >90%

    Energy Technology Data Exchange (ETDEWEB)

    Herbert, Christopher, E-mail: cherbert@bccancer.bc.ca [Department of Radiation Oncology, British Columbia Cancer Agency, Vancouver Centre, Vancouver, BC (Canada); Liu, Mitchell; Tyldesley, Scott; Morris, W. James [Department of Radiation Oncology, British Columbia Cancer Agency, Vancouver Centre, Vancouver, BC (Canada); Joffres, Michel [Department of Health Sciences, Simon Fraser University, Surrey, BC (Canada); Khaira, Mandip; Kwan, Winkle [Department of Radiation Oncology, British Columbia Cancer Agency, Fraser Valley Centre, Surrey, BC (Canada); Moiseenko, Vitali [Department of Medical Physics, British Columbia Cancer Agency, Vancouver Centre, Vancouver, BC (Canada); Pickles, Thomas [Department of Radiation Oncology, British Columbia Cancer Agency, Vancouver Centre, Vancouver, BC (Canada)

    2012-05-01

    Purpose: To identify subgroups of patients with carcinoma of the prostate treated with radical radiotherapy that have improved overall survival when disease is biochemically controlled. Methods and Materials: A cohort of 1,060 prostate cancer patients treated with radical radiotherapy was divided into nine subgroups based on National Comprehensive Cancer Network risk category and estimated 10-year overall survival (eOS 10y) derived from the age adjusted Charlson Comorbidity Index. Patients with and without biochemical control were compared with respect to overall survival. Actuarial estimates of overall survival were calculated using the Kaplan-Meier method. Univariate and multivariate Cox proportional hazards models were used for analysis of overall survival. Results: Median follow-up was 125 months (range, 51-176 months). Only the subgroups with high or intermediate risk disease and an eOS 10y of >90% had a statistically significantly improved overall survival when prostate cancer was biochemically controlled. In all other groups, biochemical control made no significant difference to overall survival. In the subgroup with high-risk disease and eOS 10y >90%, actuarial overall survival was 86.3% (95% confidence interval [CI] 78.5%-94.1%) and 62.1% (95% CI 52.9%-71.3%) for patients with biochemical control and biochemical relapse respectively (p = 0.002). In the intermediate risk group with eOS >90%, actuarial overall survival was 95.3% (95% CI 89.0%-100%) and 79.8% (95% CI 68.0%-91.6%) for biochemically controlled and biochemically relapsed patients (p = 0.033). On multivariate analysis, National Comprehensive Cancer Network risk group (p = 0.005), biochemical control (p = 0.033) and eOS 10y (p < 0.001) were statistically significant. Conclusion: Biochemical control translates into improved overall survival in patients with high or intermediate risk disease and an estimated 10-year overall survival of >90%.

  9. IRF4 rs12203592 functional variant and melanoma survival.

    Science.gov (United States)

    Potrony, Miriam; Rebollo-Morell, Aida; Giménez-Xavier, Pol; Zimmer, Lisa; Puig-Butille, Joan Anton; Tell-Marti, Gemma; Sucker, Antje; Badenas, Celia; Carrera, Cristina; Malvehy, Josep; Schadendorf, Dirk; Puig, Susana

    2017-04-15

    Inherited genetic factors may modulate clinical outcome in melanoma. Some low-to-medium risk genes in melanoma susceptibility play a role in melanoma outcome. Our aim was to assess the role of the functional IRF4 SNP rs12203592 in melanoma prognosis in two independent sets (Barcelona, N = 493 and Essen, N = 438). Genotype association analyses showed that the IRF4 rs12203592 T allele increased the risk of dying from melanoma in both sets (Barcelona: odds ratio [OR] = 6.53, 95% CI 1.38-30.87, Adj p = 0.032; Essen: OR = 1.68, 95% CI 1.04-2.72, Adj p = 0.035). Survival analyses only showed significance for the Barcelona set (hazard ratio = 4.58, 95% CI 1.11-18.92, Adj p = 0.036). This SNP was also associated with tumour localization, increasing the risk of developing melanoma in head or neck (OR = 1.79, 95% CI 1.07-2.98, Adj p = 0.032) and protecting from developing melanoma in the trunk (OR = 0.59, 95% CI 0.41-0.85, Adj p = 0.004). These findings suggest for the first time that IRF4 rs12203592 plays a role in the modulation of melanoma outcome and confirms its contribution to the localization of the primary tumour. © 2017 UICC.

  10. A note on uniform consistency of monotone function estimators

    OpenAIRE

    2009-01-01

    Recently, Dette, Neumeyer and Pilz (2005a) proposed a new monotone estimator for strictly increasing nonparametric regression functions and proved asymptotic normality. We explain two modifications of their method that can be used to obtain monotone versions of any nonparametric function estimators, for instance estimators of densities, variance functions or hazard rates. The method is appealing to practitioners because they can use their favorite method of function estimation (kernel smoothi...

  11. Adjusting survival estimates for premature transmitter failure: A case study from the Sacramento-San Joaquin Delta

    Science.gov (United States)

    Holbrook, Christopher M.; Perry, Russell W.; Brandes, Patricia L.; Adams, Noah S.

    2013-01-01

    In telemetry studies, premature tag failure causes negative bias in fish survival estimates because tag failure is interpreted as fish mortality. We used mark-recapture modeling to adjust estimates of fish survival for a previous study where premature tag failure was documented. High rates of tag failure occurred during the Vernalis Adaptive Management Plan’s (VAMP) 2008 study to estimate survival of fall-run Chinook salmon (Oncorhynchus tshawytscha) during migration through the San Joaquin River and Sacramento-San Joaquin Delta, California. Due to a high rate of tag failure, the observed travel time distribution was likely negatively biased, resulting in an underestimate of tag survival probability in this study. Consequently, the bias-adjustment method resulted in only a small increase in estimated fish survival when the observed travel time distribution was used to estimate the probability of tag survival. Since the bias-adjustment failed to remove bias, we used historical travel time data and conducted a sensitivity analysis to examine how fish survival might have varied across a range of tag survival probabilities. Our analysis suggested that fish survival estimates were low (95% confidence bounds range from 0.052 to 0.227) over a wide range of plausible tag survival probabilities (0.48–1.00), and this finding is consistent with other studies in this system. When tags fail at a high rate, available methods to adjust for the bias may perform poorly. Our example highlights the importance of evaluating the tag life assumption during survival studies, and presents a simple framework for evaluating adjusted survival estimates when auxiliary travel time data are available.

  12. Patient function, long-term survival, and use of surgery in patients with kidney cancer.

    Science.gov (United States)

    Tan, Hung-Jui; Chamie, Karim; Daskivich, Timothy J; Litwin, Mark S; Hu, Jim C

    2016-12-15

    Beyond age and comorbidity, functionality can shape the long-term survival potential of patients with cancer. Accordingly, herein the authors compared mortality and receipt of cancer-directed surgery according to patient function among older adults with kidney cancer. Using Surveillance, Epidemiology, and End Results (SEER)-Medicare data from 2000 through 2009, the authors studied 28,326 elderly subjects with primary kidney cancer. Patient function was quantified using function-related indicators, claims indicative of dysfunction and disability. Adjusting for patient and cancer characteristics, competing risk regression was used to assess the relationship between function-related indicator count and cause-specific mortality and then generalized estimating equations were used to quantify the probability of surgery. A total of 13,619 adult patients (48.1%) with at least 1 function-related indicator were identified. A higher indicator category was associated with older age, greater comorbidity, female sex, unmarried status, lower socioeconomic status, and higher stage of disease (Pkidney cancer mortality varied minimally with patient function. Patients with ≥ 2 indicators received cancer-directed surgery less often than those without disability (odds ratio, 0.61; 95% CI, 0.56-0.66), although treatment probabilities remained high for patients with locoregional disease and low for those with metastatic cancer. Among older adults with kidney cancer, functional health stands as a significant predictor of long-term survival. However, receipt of cancer-directed surgery appears largely determined by cancer stage. Patient function should be considered more heavily when determining treatment for older adults with kidney cancer. Cancer 2016;122:3776-3784. © 2016 American Cancer Society. © 2016 American Cancer Society.

  13. Apparent survival rates of forest birds in eastern Ecuador revisited: improvement in precision but no change in estimates.

    Directory of Open Access Journals (Sweden)

    John G Blake

    Full Text Available Knowledge of survival rates of Neotropical landbirds remains limited, with estimates of apparent survival available from relatively few sites and species. Previously, capture-mark-recapture models were used to estimate apparent survival of 31 species (30 passerines, 1 Trochilidae from eastern Ecuador based on data collected from 2001 to 2006. Here, estimates are updated with data from 2001-2012 to determine how additional years of data affect estimates; estimates for six additional species are provided. Models assuming constant survival had highest support for 19 of 31 species when based on 12 years of data compared to 27 when based on six; models incorporating effects of transients had the highest support for 12 of 31 species compared to four when based on 12 and six years, respectively. Average apparent survival based on the most highly-supported model (based on model averaging, when appropriate was 0.59 (± 0.02 SE across 30 species of passerines when based on 12 years and 0.57 (± 0.02 when based on six. Standard errors of survival estimates based on 12 years were approximately half those based on six years. Of 31 species in both data sets, estimates of apparent survival were somewhat lower for 13, somewhat higher for 17, and remained unchanged for one; confidence intervals for estimates based on six and 12 years of data overlapped for all species. Results indicate that estimates of apparent survival are comparable but more precise when based on longer-term data sets; standard error of the estimates was negatively correlated with numbers of captures (rs  = -0.72 and recaptures (rs  = -0.93, P<0.001 in both cases. Thus, reasonable estimates of apparent survival may be obtained with relatively few years of data if sample sizes are sufficient.

  14. On differences in radiosensitivity estimation: TCP experiments versus survival curves. A theoretical study.

    Science.gov (United States)

    Stavrev, Pavel; Stavreva, Nadejda; Ruggieri, Ruggero; Nahum, Alan

    2015-08-07

    We have compared two methods of estimating the cellular radiosensitivity of a heterogeneous tumour, namely, via cell-survival and via tumour control probability (TCP) pseudo-experiments. It is assumed that there exists intra-tumour variability in radiosensitivity and that the tumour consists predominantly of radiosensitive cells and a small number of radio-resistant cells.Using a multi-component, linear-quadratic (LQ) model of cell kill, a pseudo-experimental cell-survival versus dose curve is derived. This curve is then fitted with a mono-component LQ model describing the response of a homogeneous cell population. For the assumed variation in radiosensitivity it is shown that the composite pseudo-experimental survival curve is well approximated by the survival curve of cells with uniform radiosensitivity.For the same initial cell radiosensitivity distribution several pseudo-experimental TCP curves are simulated corresponding to different fractionation regimes. The TCP model used accounts for clonogen proliferation during a fractionated treatment. The set of simulated TCP curves is then fitted with a mono-component TCP model. As in the cell survival experiment the fit with a mono-component model assuming uniform radiosensitivity is shown to be highly acceptable.However, the best-fit values of cellular radiosensitivity produced via the two methods are very different. The cell-survival pseudo-experiment yields a high radiosensitivity value, while the TCP pseudo-experiment shows that the dose-response is dominated by the most resistant sub-population in the tumour, even when this is just a small fraction of the total.

  15. The effect of clinical performance on the survival estimates of direct restorations

    Directory of Open Access Journals (Sweden)

    Kyou-Li Kim

    2013-02-01

    Full Text Available Objectives In most retrospective studies, the clinical performance of restorations had not been considered in survival analysis. This study investigated the effect of including the clinically unacceptable cases according to modified United States Public Health Service (USPHS criteria into the failed data on the survival analysis of direct restorations as to the longevity and prognostic variables. Materials and Methods Nine hundred and sixty-seven direct restorations were evaluated. The data of 204 retreated restorations were collected from the records, and clinical performance of 763 restorations in function was evaluated according to modified USPHS criteria by two observers. The longevity and prognostic variables of the restorations were compared with a factor of involving clinically unacceptable cases into the failures using Kaplan-Meier survival analysis and Cox proportional hazard model. Results The median survival times of amalgam, composite resin and glass ionomer were 11.8, 11.0 and 6.8 years, respectively. Glass ionomer showed significantly lower longevity than composite resin and amalgam. When clinically unacceptable restorations were included into the failure, the median survival times of them decreased to 8.9, 9.7 and 6.4 years, respectively. Conclusions After considering the clinical performance, composite resin was the only material that showed a difference in the longevity (p < 0.05 and the significantly higher relative risk of student group than professor group disappeared in operator groups. Even in the design of retrospective study, clinical evaluation needs to be included.

  16. Instrumental variables estimation of exposure effects on a time-to-event endpoint using structural cumulative survival models.

    Science.gov (United States)

    Martinussen, Torben; Vansteelandt, Stijn; Tchetgen Tchetgen, Eric J; Zucker, David M

    2017-12-01

    The use of instrumental variables for estimating the effect of an exposure on an outcome is popular in econometrics, and increasingly so in epidemiology. This increasing popularity may be attributed to the natural occurrence of instrumental variables in observational studies that incorporate elements of randomization, either by design or by nature (e.g., random inheritance of genes). Instrumental variables estimation of exposure effects is well established for continuous outcomes and to some extent for binary outcomes. It is, however, largely lacking for time-to-event outcomes because of complications due to censoring and survivorship bias. In this article, we make a novel proposal under a class of structural cumulative survival models which parameterize time-varying effects of a point exposure directly on the scale of the survival function; these models are essentially equivalent with a semi-parametric variant of the instrumental variables additive hazards model. We propose a class of recursive instrumental variable estimators for these exposure effects, and derive their large sample properties along with inferential tools. We examine the performance of the proposed method in simulation studies and illustrate it in a Mendelian randomization study to evaluate the effect of diabetes on mortality using data from the Health and Retirement Study. We further use the proposed method to investigate potential benefit from breast cancer screening on subsequent breast cancer mortality based on the HIP-study. © 2017, The International Biometric Society.

  17. Estimation of failure criteria in multivariate sensory shelf life testing using survival analysis.

    Science.gov (United States)

    Giménez, Ana; Gagliardi, Andrés; Ares, Gastón

    2017-09-01

    For most food products, shelf life is determined by changes in their sensory characteristics. A predetermined increase or decrease in the intensity of a sensory characteristic has frequently been used to signal that a product has reached the end of its shelf life. Considering all attributes change simultaneously, the concept of multivariate shelf life allows a single measurement of deterioration that takes into account all these sensory changes at a certain storage time. The aim of the present work was to apply survival analysis to estimate failure criteria in multivariate sensory shelf life testing using two case studies, hamburger buns and orange juice, by modelling the relationship between consumers' rejection of the product and the deterioration index estimated using PCA. In both studies, a panel of 13 trained assessors evaluated the samples using descriptive analysis whereas a panel of 100 consumers answered a "yes" or "no" question regarding intention to buy or consume the product. PC1 explained the great majority of the variance, indicating all sensory characteristics evolved similarly with storage time. Thus, PC1 could be regarded as index of sensory deterioration and a single failure criterion could be estimated through survival analysis for 25 and 50% consumers' rejection. The proposed approach based on multivariate shelf life testing may increase the accuracy of shelf life estimations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. A mixed linear model controlling for case underascertainment across multiple cancer registries estimated time trends in survival.

    Science.gov (United States)

    Dahm, Stefan; Bertz, Joachim; Barnes, Benjamin; Kraywinkel, Klaus

    2018-01-10

    Large temporal and geographical variation in survival rates estimated from epidemiological cancer registries coupled with heterogeneity in death certificate only (DCO) notifications makes it difficult to interpret trends in survival. The aim of our study is to introduce a method for estimating such trends while accounting for heterogeneity in DCO notifications in a cancer site-specific manner. We used the data of 4.0 million cancer cases notified in 14 German epidemiological cancer registries. Annual 5-year relative survival rates from 2002 through 2013 were estimated, and proportions of DCO notifications were recorded. "DCO-excluded" survival rates were regressed on DCO proportions and calendar years using a mixed linear model with cancer registry as a random effect. Based on this model, trends in survival rates were estimated for Germany at 0% DCO. For most cancer sites and age groups, we estimated significant positive trends in survival. Age-standardized survival for all cancers combined increased by 7.1% units for women and 10.8% units for men. The described method could be used to estimate trends in cancer survival based on the data from epidemiological cancer registries with differing DCO proportions and with changing DCO proportions over time. Copyright © 2018 Elsevier Inc. All rights reserved.

  19. Estimation of direct effects for survival data by using the Aalen additive hazards model

    DEFF Research Database (Denmark)

    Martinussen, T.; Vansteelandt, S.; Gerster, M.

    2011-01-01

    We extend the definition of the controlled direct effect of a point exposure on a survival outcome, other than through some given, time-fixed intermediate variable, to the additive hazard scale. We propose two-stage estimators for this effect when the exposure is dichotomous and randomly assigned...... Aalen's additive regression for the event time, given exposure, intermediate variable and confounders. The second stage involves applying Aalen's additive model, given the exposure alone, to a modified stochastic process (i.e. a modification of the observed counting process based on the first......-stage estimates). We give the large sample properties of the estimator proposed and investigate its small sample properties by Monte Carlo simulation. A real data example is provided for illustration....

  20. Membrane based macroencapsulation devices for improved pancreatic islet survival and function

    NARCIS (Netherlands)

    Skrzypek, Katarzyna

    2017-01-01

    The research presented in this thesis is about the development of novel membrane based macroencapsulation devices for improved pancreatic islet survival and function. To improve pancreatic islets functionality by avoiding their aggregation within macroencapsulation devices, we developed a novel

  1. Estimation of Inbreeding Coefficient and Its Effects on Lamb Survival in Sheep

    Directory of Open Access Journals (Sweden)

    mohammad almasi

    2016-04-01

    Full Text Available Introduction The mating of related individuals produces an inbred offspring and leads to an increased homozygosity in the progeny, genetic variance decrease within families and increase between families. The ration of homozygosity for individuals was calculated by inbreeding coefficient. Inbred individuals may carry two alleles at a locus that are replicated from one gene in the previous generations, called identical by descent. The inbreeding coefficient should be monitored in a breeding program, since it plays an important role at decreasing of homeostasis, performance, reproduction and viability. The trend of inbreeding is an indicator for determining of inbreeding level in the herd. Inbreeding affects both phenotypic means of traits and genetic variances within population, thus it is an important factor for delimitations of genetic progress in a population. Reports showed an inbreeding increase led to decrease of phenotypic value in some of the productive and reproductive traits. Materials and Methods In the current study, the pedigree data of 14030 and 6215 records of Baluchi and Iranblack lambs that collected from 1984 to 2011 at the Abbasabad Sheep Breeding Station in Mashhad, Iran, 3588 records of Makoei lambs that collected from 1994 to 2011 at the Makoei sheep breeding station and 6140, records of Zandi lambs that collected from 1991 to 2011 at the Khejir Sheep Breeding Station in Tehran, Iran were used to estimating the inbreeding coefficient and its effects on lamb survival in these breeds. Lamb survival trait was scored as 1 and 0 for lamb surviving and not surviving at weaning weight, respectively. Inbreeding coefficient was estimated by relationship matrix algorithm (A=TDT' methodology using the CFC software program. Effects of inbreeding coefficient on lamb survival were estimated by restricted maximum likelihood (REML method under 12 different animal models using ASReml 3.0 computer programme. Coefficient of inbreeding for each

  2. Reentry trajectory and survivability estimation of small space debris with catalytic recombination

    Science.gov (United States)

    Park, Seong-Hyeon; Park, Gisu

    2017-09-01

    A code has been developed to analyze reentry trajectories and survivability of space debris. In particular, an attention was given to small sizes. Based on simple shapes such as a sphere, a cylinder, and a box with sizes of 12.5-50 cm, reentry trajectories were calculated. Materials considered were graphite epoxy, aluminum, and titanium. In total, 120 different cases were examined. The results were compared and validated with various existing codes. Good agreement was found. In the heat transfer calculation, all of the existing codes used the well known Lees' and Fay and Riddell's formulae which assume an equilibrium boundary layer flow with a super-catalytic wall where the surface recombination efficiency is regarded infinity. In the case of small space debris having sizes of 2.5-10 cm, however, the flow residence time behind a shock wave is far too short, so that the super-catalytic assumption leads to over-estimation of surface heat transfer rates. Assuming a frozen boundary layer, a finite catalytic recombination can be considered and the results were compared with that of the super-catalytic cases. Both hollow and solid spheres were considered with different sizes and materials. In total, 24 different cases were examined. The results showed that, 16 out of 24 cases survived, while only 8 cases for the super-catalytic and 19 cases for the non-catalytic walls survived, implying the importance of catalytic wall effects for the study of small space debris.

  3. Estimation of Unemployment Duration in Botoşani County Using Survival Analysis

    Directory of Open Access Journals (Sweden)

    Darabă Gabriel

    2017-01-01

    Full Text Available In this paper we aim at estimating the unemployment duration in Botosani County in order tostudy the impact of individual characteristics (gender, age, place of residence, unemploymentbenefit, etc. on the length of unemployment spells. We use Cox regression model to measure theeffects of gender, age, residential environment, etc. on the hazard rate of leaving unemploymentandKaplan-Meier estimator to compare survival probabilities among different categories ofunemployed persons. The study is carried out on a sample of 200 unemployment spellsregisteredwith the Employment Agency of Botoşani County from January 2012 to December 2015. Theresults reveal that place of residence, unemployment benefit and unemployed category have asignificant impact on unemployment spells.

  4. Survival rates of immature Ixodes pacificus (Acari: Ixodidae) ticks estimated using field-placed enclosures.

    Science.gov (United States)

    Nieto, Nathan C; Holmes, Elizabeth A; Foley, Janet E

    2010-06-01

    Granulocytic anaplasmosis (GA) and Lyme borreliosis are emerging tick-borne diseases caused by infection with Anaplasma phagocytophilum and Borrelia burgdorferi, respectively, and maintained in rodent-Ixodes spp. tick cycles, including I. pacificus in the western U.S. Ixodes pacificus has a multiple-year life cycle and B. burgdorferi and A. phagocytophilum are transstadially, but not transovarially, transmitted within ticks, thus ticks function importantly in maintaining infection in nature. In this study, the survival of larval and nymphal I. pacificus was determined using ticks placed in tubes in leaf litter from June 2005 to September 2006 at two field sites in the California northern coast range mountains and a laboratory control. In all three sites, nymphal and larval survival ranged from 90-400 d, with differences in mean survival among sites. Fewer ticks died in the autumn in the moister field sites compared with the drier incubator control treatment. The first large die-off event in late autumn occurred at all sites shortly before relative humidity increased from 80-100% and temperature declined from approximately 22-15 degrees C. The concurrent die-off in the incubator population, subject to relative humidity and temperature regimes that were invariant, suggests that survival time was dependent on other factors in addition to environmental conditions. These results suggested that many ticks exhausted resources or tolerance for relatively low humidity within six months of questing, and that higher humidity prolonged survival. Based on observed longevity, humans and other animals could acquire A. phagocytophilum infection from adult I. pacificus that were infected up to three years earlier.

  5. Functional status of hemodialysis arteriovenous fistula in kidney transplant recipients as a predictor of allograft function and survival.

    Science.gov (United States)

    Vajdič, B; Arnol, M; Ponikvar, R; Kandus, A; Buturović-Ponikvar, J

    2010-12-01

    There is no accepted policy for preserving or ligating arteriovenous fistula (AVF) after successful kidney transplantation. The aim of this study was to compare kidney graft function and survival between patients with a functional AVF at 1 year after-transplantation with those having a nonfunctional AVF. This historical cohort study included 311 kidney transplant recipients between January 2000 and December 2008 with a functional AVF at the time of transplantation. Patients were divided into 2 groups according to functional status of AVF at 1 year after transplantation. Graft function was assessed at 1 year by serum creatinine and estimated glomerular filtration rate (eGFR) using the 4-variable Modification of Diet in Renal Disease formula. Kaplan-Meier and Cox proportional hazards analyses were used to assess the relationship between the functional status of the AVF and graft survival. The 311 recipients had a mean age of 47 ± 11 years (range, 14 to 70) with 188 (60.5%) males. Patients with functional AVF at 1 year (n = 239) showed higher serum creatinine and lower eGFR values than those with nonfunctional AVF (n = 72): namely 110 ± 38 μmol/L and 69 ± 21 mL/min/1.73 m(2) versus 99 ± 30 μmol/L and 74 ± 19 mL/min/1.73 m(2), respectively (P functional AVF at 1 year after transplantation was associated with a greater incidence of eGFR functional AVF versus 75% among those with a nonfunctional AVF (P = .045). The adjusted analyses revealed the persistence of a functional AVF to be associated with an increased risk for future allograft loss (hazard ratio, 1.336; 95% CI, 1.018-1.755; P = .037). In conclusion, the persistence of a functional AVF was associated with a lower eGFR at 1 year after-transplantation and an increased risk for future allograft loss. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Cause-specific or relative survival setting to estimate population-based net survival from cancer? An empirical evaluation using women diagnosed with breast cancer in Geneva between 1981 and 1991 and followed for 20 years after diagnosis.

    Science.gov (United States)

    Schaffar, Robin; Rachet, Bernard; Belot, Aurélien; Woods, Laura

    2015-06-01

    Both cause-specific and relative survival settings can be used to estimate net survival, the survival that would be observed if the only possible underlying cause of death was the disease under study. Both resulting net survival estimators are biased by informative censoring and prone to biases related to the data settings within which each is derived. We took into account informative censoring to derive theoretically unbiased estimators and examine which of the two data settings was the most robust against incorrect assumptions in the data. We identified 2489 women in the Geneva Cancer Registry, diagnosed with breast cancer between 1981 and 1991, and estimated net survival up to 20-years using both cause-specific and relative survival settings, by tackling the informative censoring with weights. To understand the possible origins of differences between the survival estimates, we performed sensitivity analyses within each setting. We evaluated the impact of misclassification of cause of death and of using inappropriate life tables on survival estimates. Net survival was highest using the cause-specific setting, by 1% at one year and by up to around 11% twenty years after diagnosis. Differences between both sets of net survival estimates were eliminated after recoding between 15% and 20% of the non-specific deaths as breast cancer deaths. By contrast, a dramatic increase in the general population mortality rates was needed to see the survival estimates based on relative survival setting become closer to those derived from cause-specific setting. Net survival estimates derived using the cause-specific setting are very sensitive to misclassification of cause of death. Net survival estimates derived using the relative-survival setting were robust to large changes in expected mortality. The relative survival setting is recommended for estimation of long-term net survival among patients with breast cancer. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Estimation of Correlation Functions by the Random Decrement Technique

    DEFF Research Database (Denmark)

    Brincker, Rune; Krenk, Steen; Jensen, Jacob Laigaard

    1991-01-01

    The Random Decrement (RDD) Technique is a versatile technique for characterization of random signals in the time domain. In this paper a short review of the theoretical basis is given, and the technique is illustrated by estimating auto-correlation functions and cross-correlation functions on modal...... - in some cases up to 100 times faster than the FFT technique. Another important advantage is that if the RDD technique is implemented correctly, the correlation function estimates are unbiased. Comparison with exact solutions for the correlation functions shows that the RDD auto-correlation estimates...... suffer from smaller RDD auto-correlation estimation errors than the corresponding FFT estimates. However, in the case of estimating cross-correlation functions for the stochastic processes with low mutual correlation, the FFT tehcnique might be more accurate....

  8. Nonparametric Estimation in Renewal Theory I : The Empirical Renewal Function

    NARCIS (Netherlands)

    Grubel, R.; Pitts, S.M.

    1993-01-01

    We introduce a nonparametric estimator for the renewal function and discuss its properties, including consistency, asymptotic normality and asymptotic validity of bootstrap confidence regions. The underlying theme is that stochastic models can be regarded as functionals or nonlinear operators. This

  9. Container Surface Evaluation by Function Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Wendelberger, James G. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-03

    Container images are analyzed for specific surface features, such as, pits, cracks, and corrosion. The detection of these features is confounded with complicating features. These complication features include: shape/curvature, welds, edges, scratches, foreign objects among others. A method is provided to discriminate between the various features. The method consists of estimating the image background, determining a residual image and post processing to determine the features present. The methodology is not finalized but demonstrates the feasibility of a method to determine the kind and size of the features present.

  10. Expanding functional repertoires of fungal peroxisomes: contribution to growth and survival processes

    OpenAIRE

    Jun-ichi eMARUYAMA; Katsuhiko eKITAMOTO

    2013-01-01

    It has long been regarded that the primary function of fungal peroxisomes is limited to the β-oxidation of fatty acids, as mutants lacking peroxisomal function fail to grow in minimal medium containing fatty acids as the sole carbon source. However, studies in filamentous fungi have revealed that peroxisomes have diverse functional repertoires. This review describes the essential roles of peroxisomes in the growth and survival processes of filamentous fungi. One such survival mechanism involv...

  11. Unstable volatility functions: the break preserving local linear estimator

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irene

    The objective of this paper is to introduce the break preserving local linear (BPLL) estimator for the estimation of unstable volatility functions. Breaks in the structure of the conditional mean and/or the volatility functions are common in Finance. Markov switching models (Hamilton, 1989......) and threshold models (Lin and Terasvirta, 1994) are amongst the most popular models to describe the behaviour of data with structural breaks. The local linear (LL) estimator is not consistent at points where the volatility function has a break and it may even report negative values for finite samples....... The estimator presented in this paper generalises the classical LL. The BPLL maintains the desirable properties of the LL with regard to the bias and the boundary estimation, it estimates the breaks consistently and it ensures that the volatility estimates are always positive....

  12. A logistic regression estimating function for spatial Gibbs point processes

    DEFF Research Database (Denmark)

    Baddeley, Adrian; Coeurjolly, Jean-François; Rubak, Ege

    We propose a computationally efficient logistic regression estimating function for spatial Gibbs point processes. The sample points for the logistic regression consist of the observed point pattern together with a random pattern of dummy points. The estimating function is closely related...

  13. Asymptotic estimates of viscoelastic Green's functions near the wavefront

    OpenAIRE

    Hanyga, Andrzej

    2014-01-01

    Asymptotic behavior of viscoelastic Green's functions near the wavefront is expressed in terms of a causal function $g(t)$ defined in \\cite{SerHanJMP} in connection with the Kramers-Kronig dispersion relations. Viscoelastic Green's functions exhibit a discontinuity at the wavefront if $g(0) < \\infty$. Estimates of continuous and discontinuous viscoelastic Green's functions near the wavefront are obtained.

  14. Estimation of Frequency Response Functions by Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune

    1996-01-01

    A method for estimating frequency response functions by the Random Decrement technique is investigated in this paper. The method is based on the auto and cross Random Decrement functions of the input process and the output process of a linear system. The Fourier transformation of these functions ...... Decrement function. The method is demonstrated by a simulation study....

  15. Malware Function Estimation Using API in Initial Behavior

    OpenAIRE

    KAWAGUCHI, Naoto; OMOTE, Kazumasa

    2017-01-01

    Malware proliferation has become a serious threat to the Internet in recent years. Most current malware are subspecies of existing malware that have been automatically generated by illegal tools. To conduct an efficient analysis of malware, estimating their functions in advance is effective when we give priority to analyze malware. However, estimating the malware functions has been difficult due to the increasing sophistication of malware. Actually, the previous researches do not estimate the...

  16. Estimates of parabolic cylinder functions on the real axis

    OpenAIRE

    Pokrovski, Alexis

    2005-01-01

    We estimate simple combination of the parabolic cylinder functions and their derivatives. These estimates are important for the spectral analysis of non-analytically perturbed quantum harmonic oscillator. The estimates are valid in rather complicated domains and refine there the classical result of Olver. We determine the part of the real x-axis, which is within the domains of the estimates. This requires a detailed study of the image of the real x-axis in the standard quasiclassical variable.

  17. Estimation of Correlation Functions by the Random Decrement Technique

    DEFF Research Database (Denmark)

    Brincker, Rune; Krenk, S.; Jensen, Jakob Laigaard

    1993-01-01

    The Random Decrement (RDD) Technique is a versatile technique for characterization of random signals in the time domain. In this paper a short review of the theoretical basis is given, and the technique is illustrated by estimating auto-correlation functions and cross-correlation functions on modal...... - in some case up to 100 times faster that the FFT technique. Another important advantage is that if the RDD technique is implemented correctly, the correlation function estimates are unbiased. Comparison with exact solutions for the correlation functions show that the RDD auto-correlation estimates suffer...

  18. Estimation of Correlation Functions by the Random Decrement Technique

    DEFF Research Database (Denmark)

    Brincker, Rune; Krenk, Steen; Jensen, Jakob Laigaard

    The Random Decrement (RDD) Technique is a versatile technique for characterization of random signals in the time domain. In this paper a short review of the theoretical basis is given, and the technique is illustrated by estimating auto-correlation functions and cross-correlation functions on modal...... - in some case up to 100 times faster that the FFT technique. Another important advantage is that if the RDD technique is implemented correctly, the correlation function estimates are unbiased. Comparison with exact solutions for the correlation functions show that the RDD auto-correlation estimates suffer...

  19. Production Risk and the Estimation of Ex Ante Cost Functions

    OpenAIRE

    Moschini, GianCarlo

    2001-01-01

    Cost function estimation under production uncertainty is problematic because the relevant cost is conditional on unobservable expected output. If input demand functions are also stochastic, then a nonlinear errors-in-variables model is obtained and standard estimation procedures typically fail to attain consistency. But by exploiting the full implications of the expected profit maximization hypothesis that gives rise to ex ante cost functions, it is shown that the errors-in-variables problem ...

  20. Survival Estimates for the Passage of Spring-Migrating Juvenile Salmonids through Snake and Columbia River Dams and Reservoirs, 2008.

    Energy Technology Data Exchange (ETDEWEB)

    Faulkner, James R.; Smith, Steven G.; Muir, William D. [Northwest Fisheries Science Center

    2009-06-23

    In 2008, the National Marine Fisheries Service completed the sixteenth year of a study to estimate survival and travel time of juvenile salmonids Oncorhynchus spp. passing through dams and reservoirs on the Snake and Columbia Rivers. All estimates were derived from detections of fish tagged with passive integrated transponder (PIT) tags. We PIT tagged and released a total of 18,565 hatchery steelhead O. mykiss, 15,991 wild steelhead, and 9,714 wild yearling Chinook salmon O. tshawytscha at Lower Granite Dam in the Snake River. In addition, we utilized fish PIT tagged by other agencies at traps and hatcheries upstream from the hydropower system and at sites within the hydropower system in both the Snake and Columbia Rivers. These included 122,061 yearling Chinook salmon tagged at Lower Granite Dam for evaluation of latent mortality related to passage through Snake River dams. PIT-tagged smolts were detected at interrogation facilities at Lower Granite, Little Goose, Lower Monumental, Ice Harbor, McNary, John Day, and Bonneville Dams and in the PIT-tag detector trawl operated in the Columbia River estuary. Survival estimates were calculated using a statistical model for tag-recapture data from single release groups (the single-release model). Primary research objectives in 2008 were to: (1) estimate reach survival and travel time in the Snake and Columbia Rivers throughout the migration period of yearling Chinook salmon and steelhead, (2) evaluate relationships between survival estimates and migration conditions, and (3) evaluate the survival estimation models under prevailing conditions. This report provides reach survival and travel time estimates for 2008 for PIT-tagged yearling Chinook salmon (hatchery and wild), hatchery sockeye salmon O. nerka, hatchery coho salmon O. kisutch, and steelhead (hatchery and wild) in the Snake and Columbia Rivers. Additional details on the methodology and statistical models used are provided in previous reports cited here. Survival

  1. Comparative Analysis of Renal Functional Outcomes and Overall Survival of Elderly vs Nonelderly Patients Undergoing Radical Nephrectomy.

    Science.gov (United States)

    Peyton, Charles C; Rothberg, Michael B; Jiang, Victoria; Heavner, Matthew G; Hemal, Ashok K

    2017-02-01

    To evaluate changes in renal function and overall survival in elderly vs nonelderly patients undergoing radical nephrectomy (RN) for renal masses. We reviewed available records of 392 patients undergoing RN from 2008 through 2013. Patients were divided into elderly, defined as ≥70 years old (n = 110), or nonelderly (n = 282) at the time of nephrectomy. The groups were compared for perioperative characteristics, renal functional outcomes, and overall survival. Standard Student's t-tests were used for continuous variables and Fischer's exact tests for categorical comparisons. Kaplan-Meier estimate models for survival were compared using log-rank tests. Elderly patients were more likely to have comorbidities. Preoperative estimated glomerular filtration rate (GFR) of elderly patients was significantly lower (65.6 vs 77.9 mL/minute/1.73 m(2), p = 0.0002), as was GFR at discharge (47.7 vs 57.2 mL/minute/1.73 m(2), p = 0.001) and at maximum follow-up (46.8 vs 57.4 mL/minute/1.73 m(2), p = 0.001). Of the patients with GFR >60 before surgery, de novo CKD stage III progression (defined as GFR elderly and 53% nonelderly (odds ratio 2.47; 95% confidence interval 1.25-4.88; p = 0.01). Overall survival was not statistically different. When stratified for elderly and preoperative GFR Elderly patients who undergo RN have worse renal functional outcomes. Following nephrectomy, these patients are at higher risk of CKD progression than nonelderly patients. However, there does not appear to be a difference in overall survival between cohorts, even when stratified for preoperative GFR <60. These findings should be considered during preoperative decision-making.

  2. Estimating true age-dependence in survival when only adults can be observed: an example with Black-legged Kittiwakes

    Directory of Open Access Journals (Sweden)

    Frederiksen, M.

    2004-06-01

    Full Text Available In long-lived birds, pre-breeders are often difficult or impossible to observe, and even though a proportion of marked adults may be of known age, the estimation of age-specific survival is complicated by the absence of observations during the first years of life. New developments in MARK now allow use of an updated individual covariate. We used this powerful approach to model age-dependence in survival of Black-legged Kittiwakes (Rissa tridactyla at a North Sea colony. Although only 69 marked breeders were of known age, there was strong evidence for a quadratic relationship between true age and survival. We believe that this simple but powerful approach could be implemented for many species and could provide improved estimates of how survival changes with age, a central theme in life history theory.

  3. A new class of methods for functional connectivity estimation

    Science.gov (United States)

    Lin, Wutu

    Measuring functional connectivity from neural recordings is important in understanding processing in cortical networks. The covariance-based methods are the current golden standard for functional connectivity estimation. However, the link between the pair-wise correlations and the physiological connections inside the neural network is unclear. Therefore, the power of inferring physiological basis from functional connectivity estimation is limited. To build a stronger tie and better understand the relationship between functional connectivity and physiological neural network, we need (1) a realistic model to simulate different types of neural recordings with known ground truth for benchmarking; (2) a new functional connectivity method that produce estimations closely reflecting the physiological basis. In this thesis, (1) I tune a spiking neural network model to match with human sleep EEG data, (2) introduce a new class of methods for estimating connectivity from different kinds of neural signals and provide theory proof for its superiority, (3) apply it to simulated fMRI data as an application.

  4. Point Spread Function Estimation for a Terahertz Imaging System

    Directory of Open Access Journals (Sweden)

    Popescu DanC

    2010-01-01

    Full Text Available We present a method for estimating the point spread function of a terahertz imaging system designed to operate in reflection mode. The method is based on imaging phantoms with known geometry, which have patterns with sharp edges at all orientations. The point spread functions are obtained by a deconvolution technique in the Fourier domain. We validate our results by using the estimated point spread functions to deblur several images of natural scenes and by direct comparison with a point source response. The estimations turn out to be robust and produce consistent deblurring quality over the entire depth of the focal region of the imaging system.

  5. Alcohol consumption in very old age and its association with survival: A matter of health and physical function.

    Science.gov (United States)

    Agahi, Neda; Kelfve, Susanne; Lennartsson, Carin; Kåreholt, Ingemar

    2016-02-01

    Alcohol consumption in very old age is increasing; yet, little is known about the personal and health-related characteristics associated with different levels of alcohol consumption and the association between alcohol consumption and survival among the oldest old. Nationally representative data from the Swedish Panel Study of Living Conditions of the Oldest Old (SWEOLD, ages 76-101; n=863) collected in 2010/2011 were used. Mortality was analyzed until 2014. Alcohol consumption was measured with questions about frequency and amount. Drinks per month were calculated and categorized as abstainer, light-to-moderate drinker (0.5-30 drinks/month) and heavy drinker (>30 drinks/month). Multinomial logistic regressions and Laplace regressions were performed. Compared to light-to-moderate drinkers, abstainers had lower levels of education and more functional health problems, while heavy drinkers were more often men, had higher levels of education, and no serious health or functional problems. In models adjusted only for age and sex, abstainers died earlier than drinkers. Among light-to-moderate drinkers, each additional drink/month was associated with longer survival, while among heavy drinkers, each additional drink/month was associated with shorter survival. However, after adjusting for personal and health-related factors, estimates were lower and no longer statistically significant. The association between alcohol consumption and survival in very old age seems to have an inverse J-shape; abstention and heavy use is associated with shorter survival compared to light-to-moderate drinking. To a large extent, differences in survival are due to differences in baseline health and physical function. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Correlation between Pulmonary Function Indexes and Survival Time 
in Patients with Advanced Lung Cancer

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    Hui GE

    2013-07-01

    Full Text Available Background and objective To those patients with advanced lung cancer, the ultimate objective is to improve the curative effect and quality of life, lung function indexes are an important factor. We investigate the change of lung function and the relationship between pulmonary function indexs and survival time in patients with advanced lung cancer. Methods Lung function was detected in 59 cases with lung cancer and 63 normal controls. The relationship between pulmonary function indexs and survival time was analyzed. Results There was significant difference in ventilation function and diffusing capacity between in lung cancer group and control group. Vital capacity (VC, forced expiratory volume in one second (FEV1, forced vital capacity (FVC, peak expiratory flow (PEF, peak expiratory flow% (PEF%, maximal ventilatory volume (MVV were positively correlated with survival time in patients with advanced lung cancer (r=0.29, 0.28, 0.28, 0.27, 0.26, 0.28, P<0.05, residual volume/total lung capacity was negatively correlated with survival time (r=-0.31, P<0.05. Conclusion The lung function decreases in the patients with lung cancer. VC, FEV1, FVC, PEF, PEF%, MVV, residual volume/total lung capacity were correlated with survival time in patients with advanced lung cancer. The pulmonary function indexs were important marker of prognosis in patients with lung cancer.

  7. Correlation between Pulmonary Function Indexes and Survival Time 
in Patients with Advanced Lung Cancer

    OpenAIRE

    Ge, Hui; Jiang, Zhenghua; Huang, Qian; Muyun ZHU; Yang, Jie

    2013-01-01

    Background and objective To those patients with advanced lung cancer, the ultimate objective is to improve the curative effect and quality of life, lung function indexes are an important factor. We investigate the change of lung function and the relationship between pulmonary function indexs and survival time in patients with advanced lung cancer. Methods Lung function was detected in 59 cases with lung cancer and 63 normal controls. The relationship between pulmonary function indexs and surv...

  8. Development and validation of risk prediction equations to estimate survival in patients with colorectal cancer: cohort study.

    Science.gov (United States)

    Hippisley-Cox, Julia; Coupland, Carol

    2017-06-15

    Objective  To develop and externally validate risk prediction equations to estimate absolute and conditional survival in patients with colorectal cancer. Design  Cohort study. Setting  General practices in England providing data for the QResearch database linked to the national cancer registry. Participants  44 145 patients aged 15-99 with colorectal cancer from 947 practices to derive the equations. The equations were validated in 15 214 patients with colorectal cancer from 305 different QResearch practices and 437 821 patients with colorectal cancer from the national cancer registry. Main outcome measures  The primary outcome was all cause mortality and secondary outcome was colorectal cancer mortality. Methods  Cause specific hazards models were used to predict risks of colorectal cancer mortality and other cause mortality accounting for competing risks, and these risk estimates were combined to obtain risks of all cause mortality. Separate equations were derived for men and women. Several variables were tested: age, ethnicity, deprivation score, cancer stage, cancer grade, surgery, chemotherapy, radiotherapy, smoking status, alcohol consumption, body mass index, family history of bowel cancer, anaemia, liver function test result, comorbidities, use of statins, use of aspirin, clinical values for anaemia, and platelet count. Measures of calibration and discrimination were determined in both validation cohorts at 1, 5, and 10 years. Results  The final models included the following variables in men and women: age, deprivation score, cancer stage, cancer grade, smoking status, colorectal surgery, chemotherapy, family history of bowel cancer, raised platelet count, abnormal liver function, cardiovascular disease, diabetes, chronic renal disease, chronic obstructive pulmonary disease, prescribed aspirin at diagnosis, and prescribed statins at diagnosis. Improved survival in women was associated with younger age, earlier stage of cancer, well or

  9. Functional Status, Time to Transplantation, and Survival Benefit of Kidney Transplantation Among Wait-Listed Candidates

    Science.gov (United States)

    Reese, Peter P.; Shults, Justine; Bloom, Roy D.; Mussell, Adam; Harhay, Meera N.; Abt, Peter; Levine, Matthew; Johansen, Kirsten L.; Karlawish, Jason T.; Feldman, Harold I.

    2015-01-01

    Background In the context of an aging end-stage renal disease population with multiple comorbidities, transplantation professionals face challenges in evaluating the global health of patients awaiting kidney transplantation. Functional status might be useful for identifying which patients will derive a survival benefit from transplantation versus dialysis. Study Design Retrospective cohort study of wait-listed patients using data on functional status from a national dialysis provider linked to United Network for Organ Sharing registry data. Setting & Participants Adult kidney transplant candidates added to the waiting list between the years 2000 and 2006. Predictor Physical function scale of the Medical Outcomes Study 36-Item Short Form Healthy Survey, analyzed as a time-varying covariate. Outcomes Kidney transplantation; Survival benefit of transplantation versus remaining wait-listed. Measurements We used multivariable Cox regression to assess the association between physical function with study outcomes. In survival benefit analyses, transplant status was modeled as a time-varying covariate. Results The cohort comprised 19,242 kidney transplant candidates (median age, 51 years; 36% black race) receiving maintenance dialysis. Candidates in the lowest baseline physical function quartile were more likely to be inactivated (adjusted HR vs. highest quartile, 1.30; 95% CI, 1.21-1.39) and less likely to undergo transplantation (adjusted HR vs. highest quartile, 0.64; 95% CI, 0.61-0.68). After transplantation, worse physical function was associated with shorter 3-year survival (84% vs. 92% for the lowest vs. highest function quartiles). However, compared to dialysis, transplantation was associated with a statistically significant survival benefit by 9 months for patients in every function quartile. Limitations Functional status is self-reported. Conclusions Even patients with low function appear to live longer with kidney transplantation versus dialysis. For waitlisted

  10. Lipschitz estimates for convex functions with respect to vector fields

    Directory of Open Access Journals (Sweden)

    Valentino Magnani

    2012-12-01

    Full Text Available We present Lipschitz continuity estimates for a class of convex functions with respect to Hörmander vector fields. These results have been recently obtained in collaboration with M. Scienza, [22].

  11. Genetic parameter estimates for functional herd life for the South ...

    African Journals Online (AJOL)

    Genetic parameter estimates for functional herd life for the South African Jersey breed using a multiple trait linear model (Short Communication) ... The secondary objective was to compare estimates of genetic parameters from the linear sire and animal models. Data and pedigree records on purebred Jersey cows that ...

  12. Conditional scale function estimate in the presence of unknown ...

    African Journals Online (AJOL)

    This paper considers the problem of nonparametric estimation of conditional scale function of time series, based on quantile regression methodology of Koenker and Bassett (1978). We use a flexible model introduced in Mwita (2003), that makes no moment assumptions, and discuss an estimate which we get by inverting a ...

  13. Survival Estimates for the Passage of Juvenile Salmonids through Snake River Dams and Reservoirs, 1994 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Muir, William D.

    1995-02-01

    In 1994, the National Marine Fisheries Service and the University of Washington completed the second year of a multi-year study to estimate survival of juvenile salmonids (Oncorhynchus spp.) passing through the dams and reservoirs of the Snake River. Actively migrating smolts were collected at selected locations above, at, and below Lower Granite Dam, tagged with passive integrated transponder (PIT) tags, and released to continue their downstream migration. Survival estimates were calculated using the Single-Release, Modified Single-Release, and Paired-Release Models.

  14. Nonparametric estimation of a convex bathtub-shaped hazard function

    OpenAIRE

    Jankowski, Hanna K.; Wellner, Jon A.

    2009-01-01

    In this paper, we study the nonparametric maximum likelihood estimator (MLE) of a convex hazard function. We show that the MLE is consistent and converges at a local rate of n2/5 at points x0 where the true hazard function is positive and strictly convex. Moreover, we establish the pointwise asymptotic distribution theory of our estimator under these same assumptions. One notable feature of the nonparametric MLE studied here is that no arbitrary choice of tuning parameter (or complicated data...

  15. METHODS FOR ESTIMATING THE PARAMETERS OF THE POWER FUNCTION DISTRIBUTION.

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    azam zaka

    2013-10-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE In this paper, we present some methods for estimating the parameters of the two parameter Power function distribution. We used the least squares method (LSM, relative least squares method (RELS and ridge regression method (RR. Sampling behavior of the estimates is indicated by a Monte Carlo simulation. The objective of identifying the best estimator amongst them we use the Total Deviation (T.D and Mean Square Error (M.S.E as performance index. We determined the best method for estimation using different values for the parameters and different sample sizes.

  16. Symptomatic BK Virus Infection Is Associated with Kidney Function Decline and Poor Overall Survival in Allogeneic Hematopoietic Stem Cell Recipients

    Science.gov (United States)

    Abudayyeh, Ala; Hamdi, Amir; Lin, Heather; Abdelrahim, Maen; Rondon, Gabriela; Andersson, Borje S; Afrough, Aimaz; Martinez, Charles S; Tarrand, Jeffrey J; Kontoyiannis, Dimitrios P.; Marin, David; Gaber, A. Osama; Salahudeen, Abdulla; Oran, Betul; Chemaly, Roy F.; Olson, Amanda; Jones, Roy; Popat, Uday; Champlin, Richard E; Shpall, Elizabeth J.; Winkelmayer, Wolfgang C.; Rezvani, Katayoun

    2017-01-01

    Nephropathy due to BK virus infection is an evolving challenge in patients undergoing hematopoietic stem cell transplantation. We hypothesized that BKV infection was a marker of Kidney Function Decline and a poor prognostic factor in HSCT recipients who experience this complication. In this retrospective study, we analyzed all patients who underwent their first allogeneic hematopoietic stem cell transplantation at our institution between 2004 and 2012. We evaluated the incidence of persistent kidney function decline, which was defined as a confirmed reduction in estimated glomerular filtration rate of at least 25% from baseline using the CKD-EPI equation. Cox proportional hazard regression was used to model the cause-specific hazard of kidney function decline and Fine and Gray’s method was used to account for the competing risks of death. Among 2477 recipients of a first allogeneic hematopoietic stem cell transplantation, BK viruria was detected in 25% (n=629) and kidney function decline in 944 (38.1%). On multivariate analysis, after adjusting for age, sex, acute graft-versus-host disease, chronic graft versus host disease, preparative conditioning regimen, and graft source, BK viruria remained a significant risk factor for kidney function decline (P <0.001). In addition, patients with BKV infection and kidney function decline experienced worse overall survival. Post-allogeneic hematopoietic stem cell transplantation, BKV infection was strongly and independently associated with subsequent kidney function decline and worse patient survival after HSCT. PMID:26608093

  17. A product of heme catabolism modulates bacterial function and survival.

    Directory of Open Access Journals (Sweden)

    Christopher L Nobles

    Full Text Available Bilirubin is the terminal metabolite in heme catabolism in mammals. After deposition into bile, bilirubin is released in large quantities into the mammalian gastrointestinal (GI tract. We hypothesized that intestinal bilirubin may modulate the function of enteric bacteria. To test this hypothesis, we investigated the effect of bilirubin on two enteric pathogens; enterohemorrhagic E. coli (EHEC, a Gram-negative that causes life-threatening intestinal infections, and E. faecalis, a Gram-positive human commensal bacterium known to be an opportunistic pathogen with broad-spectrum antibiotic resistance. We demonstrate that bilirubin can protect EHEC from exogenous and host-generated reactive oxygen species (ROS through the absorption of free radicals. In contrast, E. faecalis was highly susceptible to bilirubin, which causes significant membrane disruption and uncoupling of respiratory metabolism in this bacterium. Interestingly, similar results were observed for other Gram-positive bacteria, including B. cereus and S. aureus. A model is proposed whereby bilirubin places distinct selective pressure on enteric bacteria, with Gram-negative bacteria being protected from ROS (positive outcome and Gram-positive bacteria being susceptible to membrane disruption (negative outcome. This work suggests bilirubin has differential but biologically relevant effects on bacteria and justifies additional efforts to determine the role of this neglected waste catabolite in disease processes, including animal models.

  18. An improved method for estimating the frequency correlation function

    KAUST Repository

    Chelli, Ali

    2012-04-01

    For time-invariant frequency-selective channels, the transfer function is a superposition of waves having different propagation delays and path gains. In order to estimate the frequency correlation function (FCF) of such channels, the frequency averaging technique can be utilized. The obtained FCF can be expressed as a sum of auto-terms (ATs) and cross-terms (CTs). The ATs are caused by the autocorrelation of individual path components. The CTs are due to the cross-correlation of different path components. These CTs have no physical meaning and leads to an estimation error. We propose a new estimation method aiming to improve the estimation accuracy of the FCF of a band-limited transfer function. The basic idea behind the proposed method is to introduce a kernel function aiming to reduce the CT effect, while preserving the ATs. In this way, we can improve the estimation of the FCF. The performance of the proposed method and the frequency averaging technique is analyzed using a synthetically generated transfer function. We show that the proposed method is more accurate than the frequency averaging technique. The accurate estimation of the FCF is crucial for the system design. In fact, we can determine the coherence bandwidth from the FCF. The exact knowledge of the coherence bandwidth is beneficial in both the design as well as optimization of frequency interleaving and pilot arrangement schemes. © 2012 IEEE.

  19. On optimality of the empirical distribution function for the estimation ...

    African Journals Online (AJOL)

    In this work we present some results on the optimality of the empirical distribution function as estimator of the invariant distribution function of an ergodic diffusion process. The results presented were obtained in different previous works under conditions that are are rewritten in a unified form that make comparable those ...

  20. Coefficient estimates for certain subclass of bi-univalent functions

    Science.gov (United States)

    Omar, Rashidah; Halim, Suzeini Abdul; Janteng, Aini

    2017-08-01

    In this paper, a subclass of bi-univalent functions is introduced using subordination. Estimates on the initial coefficients and the Fekete-Szegö inequality are determined for functions in this subclass. The results would generalize the previous related works of several earlier authors.

  1. ANP AFFECTS CARDIAC REMODELING, FUNCTION, HEART FAILURE AND SURVIVAL IN A MOUSE MODEL OF DILATED CARDIOMYOPATHY

    OpenAIRE

    Wang, Dong; Gladysheva, Inna P.; Fan, Tai-Hwang M.; Sullivan, Ryan; Houng, Aiilyan K.; Reed, Guy L.

    2013-01-01

    Dilated cardiomyopathy is a frequent cause of heart failure and death. Atrial natriuretic peptide (ANP) is a biomarker of dilated cardiomyopathy, but there is controversy whether ANP modulates the development of heart failure. Therefore we examined whether ANP affects heart failure, cardiac remodeling, function and survival in a well-characterized, transgenic model of dilated cardiomyopathy. Mice with dilated cardiomyopathy with normal ANP levels survived longer than mice with partial ANP (p

  2. Shifting paradigms in the estimation of survival for castration-resistant prostate cancer: A tertiary academic center experience.

    Science.gov (United States)

    Afshar, Mehran; Evison, Felicity; James, Nicholas D; Patel, Prashant

    2015-08-01

    Castration-resistant prostate cancer (CRPC) has retained a guarded prognosis, with historical survival estimates of 18 to 24 months. However, the landscape of available therapy has changed, and the emphasis has altered from supportive to active treatment. Few large series from real-world populations exist in the contemporary era with fully mature survival data to confirm the indication based on clinical trials that patients with CRPC are surviving far longer than the historical estimates. We aim to review a large patient cohort with CRPC and provide mature survival data. Using the electronic histopathology database at Queen Elizabeth Hospital, Birmingham, UK, all prostate-specific antigentest results between April 2006 and September 2007 were extracted, and patients satisfying the American Society for Radiation Oncology (ASTRO) definition of hormone failure were identified. Electronic records were reviewed and variables were collected, including survival, treatment, biochemistry, histopathology, and demographics. Probability of survival, and of developing metastasis or CRPC, was determined using the Kaplan-Meier method. Patients were stratified into 3 groups, namely, D0--no metastasis at diagnosis but later appearance, D1--no metastasis at diagnosis or at last follow-up, and D2--metastasis at diagnosis. From 8,062 patient-prostate-specific antigen episodes, we identified 447 patients meeting the criteria. A notes review revealed 147 patients with CRPC. Median overall survival (OS) from diagnosis was 84.7 months (95% CI: 73-89), and 129 deaths had occurred (88%). Median OS from diagnosis for D0, D1, and D2 patients was 100.4, 180.1, and 58.9 months, respectively (P< 0.0001), and median OS from CRPC was 40 months (95% CI: 31-58), 82.9 (95% CI: 72-94; P = 0.0125), and 38.7 months (95% CI: 33-46), respectively. One-quarter of patients survived 6 years after development of CRPC. Metastasis is the key prognostic event. Some current international guidelines quote ≤19

  3. Survival probabilities of loggerhead sea turtles (Caretta caretta estimated from capture-mark-recapture data in the Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Paolo Casale

    2007-06-01

    Full Text Available Survival probabilities of loggerhead sea turtles (Caretta caretta are estimated for the first time in the Mediterranean by analysing 3254 tagging and 134 re-encounter data from this region. Most of these turtles were juveniles found at sea. Re-encounters were live resightings and dead recoveries and data were analysed with Barker’s model, a modified version of the Cormack-Jolly-Seber model which can combine recapture, live resighting and dead recovery data. An annual survival probability of 0.73 (CI 95% = 0.67-0.78; n=3254 was obtained, and should be considered as a conservative estimate due to an unknown, though not negligible, tag loss rate. This study makes a preliminary estimate of the survival probabilities of in-water developmental stages for the Mediterranean population of endangered loggerhead sea turtles and provides the first insights into the magnitude of the suspected human-induced mortality in the region. The model used here for the first time on sea turtles could be used to obtain survival estimates from other data sets with few or no true recaptures but with other types of re-encounter data, which are a common output of tagging programmes involving these wide-ranging animals.

  4. Between-year breeding dispersal by White-headed Woodpeckers: A caution about using color bands to estimate survival

    Science.gov (United States)

    Teresa J Lorenz

    2016-01-01

    Between-year breeding dispersal has not been previously documented in White-headed Woodpeckers (Picoides albolarvatus). Therefore, resightings of color-banded adults on previous years’ breeding territories have been considered a means of estimating annual adult survival. From 2013 to 2015, I observed 2 cases of between-year breeding dispersal by...

  5. Estimates of conditional survival in gastric cancer reveal a reduction of racial disparities with long-term follow-up.

    Science.gov (United States)

    Luyimbazi, David; Nelson, Rebecca A; Choi, Audrey H; Li, Lily; Chao, Joseph; Sun, Virginia; Hamner, John B; Kim, Joseph

    2015-02-01

    In prior analyses, conditional survival (CS) estimates for gastric cancer have weighed clinical and pathologic factors to predict prognosis at time intervals after surgery. Since racial disparities in gastric cancer outcomes were not considered, our objective was to determine whether race influences CS estimates. Data from the Surveillance, Epidemiology, and End Results cancer registry were used to identify gastric adenocarcinoma patients who underwent curative surgical intervention between 1988 and 2005. Five-year relative conditional survival (RCS) was computed for patients who survived at least 1 to 5 years after surgery. RCS was calculated by assessing observed and expected survival in an age- and race-matched standard population. Results were compared across time and racial groups (white, black, and Asian) using z test statistics. Of 14,067 patients, 63.8 % were white, 15.5 % black, and 20.7 % Asian. Racial disparities among groups were observed with improved survival of Asians at time point zero and improved RCS at 1 year. At 5 years following curative surgery, each racial group had increased RCS and the greatest magnitude of relative increase was observed in white and black patients (121 and 118 %, respectively). Comparison of RCS at the 5-year time point revealed a reduction of racial disparities in survival among the three groups. Our investigation shows that racial disparities in gastric cancer outcomes are pronounced at the time of curative surgery but diminish after years of survival, thus suggesting race has less influence over outcomes the longer patients survive. The reasons for reduction of racial disparities remain unclear and warrant future study.

  6. First Direct Evidence for Natal Wintering Ground Fidelity and Estimate of Juvenile Survival in the New Zealand Southern Right Whale Eubalaena australis.

    Science.gov (United States)

    Carroll, E L; Fewster, R M; Childerhouse, S J; Patenaude, N J; Boren, L; Baker, C S

    2016-01-01

    Juvenile survival and recruitment can be more sensitive to environmental, ecological and anthropogenic factors than adult survival, influencing population-level processes like recruitment and growth rate in long-lived, iteroparous species such as southern right whales. Conventionally, Southern right whales are individually identified using callosity patterns, which do not stabilise until 6-12 months, by which time the whale has left its natal wintering grounds. Here we use DNA profiling of skin biopsy samples to identify individual Southern right whales from year of birth and document their return to the species' primary wintering ground in New Zealand waters, the Subantarctic Auckland Islands. We find evidence of natal fidelity to the New Zealand wintering ground by the recapture of 15 of 57 whales, first sampled in year of birth and available for subsequent recapture, during winter surveys to the Auckland Islands in 1995-1998 and 2006-2009. Four individuals were recaptured at the ages of 9 to 11, including two females first sampled as calves in 1998 and subsequently resampled as cows with calves in 2007. Using these capture-recapture records of known-age individuals, we estimate changes in survival with age using Cormack-Jolly-Seber models. Survival is modelled using discrete age classes and as a continuous function of age. Using a bootstrap method to account for uncertainty in model selection and fitting, we provide the first direct estimate of juvenile survival for this population. Our analyses indicate a high annual apparent survival for juveniles at between 0.87 (standard error (SE) 0.17, to age 1) and 0.95 (SE 0.05: ages 2-8). Individual identification by DNA profiling is an effective method for long-term demographic and genetic monitoring, particularly in animals that change identifiable features as they develop or experience tag loss over time.

  7. Survival rates indicate that correlations between community-weighted mean traits and environments can be unreliable estimates of the adaptive value of traits.

    Science.gov (United States)

    Laughlin, Daniel C; Strahan, Robert T; Adler, Peter B; Moore, Margaret M

    2018-01-22

    Correlations between community-weighted mean (CWM) traits and environmental gradients are often assumed to quantify the adaptive value of traits. We tested this assumption by comparing these correlations with models of survival probability using 46 perennial species from long-term permanent plots in pine forests of Arizona. Survival was modelled as a function of trait × environment interactions, plant size, climatic variation and neighbourhood competition. The effect of traits on survival depended on the environmental conditions, but the two statistical approaches were inconsistent. For example, CWM-specific leaf area (SLA) and soil fertility were uncorrelated. However, survival was highest for species with low SLA in infertile soil, a result which agreed with expectations derived from the physiological trade-off underpinning leaf economic theory. CWM trait-environment relationships were unreliable estimates of how traits affected survival, and should only be used in predictive models when there is empirical support for an evolutionary trade-off that affects vital rates. © 2018 John Wiley & Sons Ltd/CNRS.

  8. How do we estimate survival? External validation of a tool for survival estimation in patients with metastatic bone disease-decision analysis and comparison of three international patient populations.

    Science.gov (United States)

    Piccioli, Andrea; Spinelli, M Silvia; Forsberg, Jonathan A; Wedin, Rikard; Healey, John H; Ippolito, Vincenzo; Daolio, Primo Andrea; Ruggieri, Pietro; Maccauro, Giulio; Gasbarrini, Alessandro; Biagini, Roberto; Piana, Raimondo; Fazioli, Flavio; Luzzati, Alessandro; Di Martino, Alberto; Nicolosi, Francesco; Camnasio, Francesco; Rosa, Michele Attilio; Campanacci, Domenico Andrea; Denaro, Vincenzo; Capanna, Rodolfo

    2015-05-22

    We recently developed a clinical decision support tool, capable of estimating the likelihood of survival at 3 and 12 months following surgery for patients with operable skeletal metastases. After making it publicly available on www.PATHFx.org , we attempted to externally validate it using independent, international data. We collected data from patients treated at 13 Italian orthopaedic oncology referral centers between 2010 and 2013, then applied to PATHFx, which generated a probability of survival at three and 12-months for each patient. We assessed accuracy using the area under the receiver-operating characteristic curve (AUC), clinical utility using Decision Curve Analysis (DCA), and compared the Italian patient data to the training set (United States) and first external validation set (Scandinavia). The Italian dataset contained 287 records with at least 12 months follow-up information. The AUCs for the three-month and 12-month estimates was 0.80 and 0.77, respectively. There were missing data, including the surgeon's estimate of survival that was missing in the majority of records. Physiologically, Italian patients were similar to patients in the training and first validation sets. However notable differences were observed in the proportion of those surviving three and 12-months, suggesting differences in referral patterns and perhaps indications for surgery. PATHFx was successfully validated in an Italian dataset containing missing data. This study demonstrates its broad applicability to European patients, even in centers with differing treatment philosophies from those previously studied.

  9. Mutations, clinical findings and survival estimates in South American patients with X-linked adrenoleukodystrophy.

    Directory of Open Access Journals (Sweden)

    Fernanda dos Santos Pereira

    Full Text Available UNLABELLED: In this study, we analyzed the ABCD1 gene in X-linked adrenoleukodystrophy (X-ALD patients and relatives from 38 unrelated families from South America, as well as phenotypic proportions, survival estimates, and the potential effect of geographical origin in clinical characteristics. METHODS: X- ALD patients from Brazil, Argentina and Uruguay were invited to participate in molecular studies to determine their genetic status, characterize the mutations and improve the genetic counseling of their families. All samples were screened by SSCP analysis of PCR fragments, followed by automated DNA sequencing to establish the specific mutation in each family. Age at onset and at death, male phenotypes, genetic status of women, and the effect of family and of latitude of origin were also studied. RESULTS: We identified thirty-six different mutations (twelve novel. This population had an important allelic heterogeneity, as only p.Arg518Gln was repeatedly found (three families. Four cases carried de novo mutations. Intra-familiar phenotype variability was observed in all families. Out of 87 affected males identified, 65% had the cerebral phenotype (CALD. The mean (95% CI ages at onset and at death of the CALD were 10.9 (9.1-12.7 and 24.7 (19.8-29.6 years. No association was found between phenotypic manifestations and latitude of origin. One index-case was a girl with CALD who carried an ABCD1 mutation, and had completely skewed X inactivation. CONCLUSIONS: This study extends the spectrum of mutations in X-ALD, confirms the high rates of de novo mutations and the absence of common mutations, and suggests a possible high frequency of cerebral forms in our population.

  10. Mutations, Clinical Findings and Survival Estimates in South American Patients with X-Linked Adrenoleukodystrophy

    Science.gov (United States)

    Pereira, Fernanda dos Santos; Matte, Ursula; Habekost, Clarissa Troller; de Castilhos, Raphael Machado; El Husny, Antonette Souto; Lourenço, Charles Marques; Vianna-Morgante, Angela M.; Giuliani, Liane; Galera, Marcial Francis; Honjo, Rachel; Kim, Chong Ae; Politei, Juan; Vargas, Carmen Regla; Jardim, Laura Bannach

    2012-01-01

    In this study, we analyzed the ABCD1 gene in X-linked adrenoleukodystrophy (X-ALD) patients and relatives from 38 unrelated families from South America, as well as phenotypic proportions, survival estimates, and the potential effect of geographical origin in clinical characteristics. Methods X- ALD patients from Brazil, Argentina and Uruguay were invited to participate in molecular studies to determine their genetic status, characterize the mutations and improve the genetic counseling of their families. All samples were screened by SSCP analysis of PCR fragments, followed by automated DNA sequencing to establish the specific mutation in each family. Age at onset and at death, male phenotypes, genetic status of women, and the effect of family and of latitude of origin were also studied. Results We identified thirty-six different mutations (twelve novel). This population had an important allelic heterogeneity, as only p.Arg518Gln was repeatedly found (three families). Four cases carried de novo mutations. Intra-familiar phenotype variability was observed in all families. Out of 87 affected males identified, 65% had the cerebral phenotype (CALD). The mean (95% CI) ages at onset and at death of the CALD were 10.9 (9.1–12.7) and 24.7 (19.8–29.6) years. No association was found between phenotypic manifestations and latitude of origin. One index-case was a girl with CALD who carried an ABCD1 mutation, and had completely skewed X inactivation. Conclusions This study extends the spectrum of mutations in X-ALD, confirms the high rates of de novo mutations and the absence of common mutations, and suggests a possible high frequency of cerebral forms in our population. PMID:22479560

  11. Estimating the probability of survival of individual shortleaf pine (Pinus echinata mill.) trees

    Science.gov (United States)

    Sudip Shrestha; Thomas B. Lynch; Difei Zhang; James M. Guldin

    2012-01-01

    A survival model is needed in a forest growth system which predicts the survival of trees on individual basis or on a stand basis (Gertner, 1989). An individual-tree modeling approach is one of the better methods available for predicting growth and yield as it provides essential information about particular tree species; tree size, tree quality and tree present status...

  12. Estimation of presampling modulation transfer function in synchrotron radiation microtomography

    CERN Document Server

    Mizutani, Ryuta; Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

    2016-01-01

    The spatial resolution achieved by recent synchrotron radiation microtomographs should be estimated from the modulation transfer function (MTF) on the micrometer scale. Step response functions of a synchrotron radiation microtomograph were determined by the slanted edge method by using high-precision surfaces of diamond crystal and ion-milled aluminum wire. Tilted reconstruction was introduced to enable any edge to be used as the slanted edge by defining the reconstruction pixel matrix in an arbitrary orientation. MTFs were estimated from the step response functions of the slanted edges. The obtained MTFs coincided with MTF values estimated from square-wave patterns milled on the aluminum surface. Although x-ray refraction influences should be taken into account to evaluate MTFs, any flat surfaces with nanometer roughness can be used to determine the spatial resolutions of microtomographs.

  13. Global and regional estimates of cancer mortality and incidence by site: I. Application of regional cancer survival model to estimate cancer mortality distribution by site

    Directory of Open Access Journals (Sweden)

    Lopez Alan D

    2002-12-01

    Full Text Available Abstract Background The Global Burden of Disease 2000 (GBD 2000 study starts from an analysis of the overall mortality envelope in order to ensure that the cause-specific estimates add to the total all cause mortality by age and sex. For regions where information on the distribution of cancer deaths is not available, a site-specific survival model was developed to estimate the distribution of cancer deaths by site. Methods An age-period-cohort model of cancer survival was developed based on data from the Surveillance, Epidemiology, and End Results (SEER. The model was further adjusted for the level of economic development in each region. Combined with the available incidence data, cancer death distributions were estimated and the model estimates were validated against vital registration data from regions other than the United States. Results Comparison with cancer mortality distribution from vital registration confirmed the validity of this approach. The model also yielded the cancer mortality distribution which is consistent with the estimates based on regional cancer registries. There was a significant variation in relative interval survival across regions, in particular for cancers of bladder, breast, melanoma of the skin, prostate and haematological malignancies. Moderate variations were observed among cancers of colon, rectum, and uterus. Cancers with very poor prognosis such as liver, lung, and pancreas cancers showed very small variations across the regions. Conclusions The survival model presented here offers a new approach to the calculation of the distribution of deaths for areas where mortality data are either scarce or unavailable.

  14. A comparison of dependence function estimators in multivariate extremes

    KAUST Repository

    Vettori, Sabrina

    2017-05-11

    Various nonparametric and parametric estimators of extremal dependence have been proposed in the literature. Nonparametric methods commonly suffer from the curse of dimensionality and have been mostly implemented in extreme-value studies up to three dimensions, whereas parametric models can tackle higher-dimensional settings. In this paper, we assess, through a vast and systematic simulation study, the performance of classical and recently proposed estimators in multivariate settings. In particular, we first investigate the performance of nonparametric methods and then compare them with classical parametric approaches under symmetric and asymmetric dependence structures within the commonly used logistic family. We also explore two different ways to make nonparametric estimators satisfy the necessary dependence function shape constraints, finding a general improvement in estimator performance either (i) by substituting the estimator with its greatest convex minorant, developing a computational tool to implement this method for dimensions $$D\\\\ge 2$$D≥2 or (ii) by projecting the estimator onto a subspace of dependence functions satisfying such constraints and taking advantage of Bernstein–Bézier polynomials. Implementing the convex minorant method leads to better estimator performance as the dimensionality increases.

  15. Bayesian error estimation in density-functional theory

    DEFF Research Database (Denmark)

    Mortensen, Jens Jørgen; Kaasbjerg, Kristen; Frederiksen, Søren Lund

    2005-01-01

    We present a practical scheme for performing error estimates for density-functional theory calculations. The approach, which is based on ideas from Bayesian statistics, involves creating an ensemble of exchange-correlation functionals by comparing with an experimental database of binding energies...... for molecules and solids. Fluctuations within the ensemble can then be used to estimate errors relative to experiment on calculated quantities such as binding energies, bond lengths, and vibrational frequencies. It is demonstrated that the error bars on energy differences may vary by orders of magnitude...

  16. Nonparametric estimation of a convex bathtub-shaped hazard function.

    Science.gov (United States)

    Jankowski, Hanna K; Wellner, Jon A

    2009-11-01

    In this paper, we study the nonparametric maximum likelihood estimator (MLE) of a convex hazard function. We show that the MLE is consistent and converges at a local rate of n(2/5) at points x(0) where the true hazard function is positive and strictly convex. Moreover, we establish the pointwise asymptotic distribution theory of our estimator under these same assumptions. One notable feature of the nonparametric MLE studied here is that no arbitrary choice of tuning parameter (or complicated data-adaptive selection of the tuning parameter) is required.

  17. Xenon treatment protects against cold ischemia associated delayed graft function and prolongs graft survival in rats.

    Science.gov (United States)

    Zhao, H; Watts, H R; Chong, M; Huang, H; Tralau-Stewart, C; Maxwell, P H; Maze, M; George, A J T; Ma, D

    2013-08-01

    Prolonged hypothermic storage causes ischemia-reperfusion injury (IRI) in the renal graft, which is considered to contribute to the occurrence of the delayed graft function (DGF) and chronic graft failure. Strategies are required to protect the graft and to prolong renal graft survival. We demonstrated that xenon exposure to human proximal tubular cells (HK-2) led to activation of range of protective proteins. Xenon treatment prior to or after hypothermia-hypoxia challenge stabilized the HK-2 cellular structure, diminished cytoplasmic translocation of high-mobility group box (HMGB) 1 and suppressed NF-κB activation. In the syngeneic Lewis-to-Lewis rat model of kidney transplantation, xenon exposure to donors before graft retrieval or to recipients after engraftment decreased caspase-3 expression, localized HMGB-1 within nuclei and prevented TLR-4/NF-κB activation in tubular cells; serum pro-inflammatory cytokines IL-1β, IL-6 and TNF-α were reduced and renal function was preserved. Xenon treatment of graft donors or of recipients prolonged renal graft survival following IRI in both Lewis-to-Lewis isografts and Fischer-to-Lewis allografts. Xenon induced cell survival or graft functional recovery was abolished by HIF-1α siRNA. Our data suggest that xenon treatment attenuates DGF and enhances graft survival. This approach could be translated into clinical practice leading to a considerable improvement in long-term graft survival. © Copyright 2013 The American Society of Transplantation and the American Society of Transplant Surgeons.

  18. Estimating probability density functions and entropies of chua's circuit using b-spline functions

    OpenAIRE

    Savacı, Ferit Acar; Güngör, Mesut

    2012-01-01

    n this paper, first the probability density functions (PDFs) of the states of Chua's circuit have been estimated using B-spline functions and then the state entropies of Chua's circuit with respect to the bifurcation parameter have been obtained. The results of the proposed B-spline density estimator have been compared with the results obtained from the Parzen density estimator. © 2012 World Scientific Publishing Company.

  19. Extension of Cox Proportional Hazard Model for Estimation of Interrelated Age-Period-Cohort Effects on Cancer Survival

    OpenAIRE

    Mdzinarishvili, Tengiz; Gleason, Michael X.; Kinarsky, Leo; Sherman, Simon

    2011-01-01

    In the frame of the Cox proportional hazard (PH) model, a novel two-step procedure for estimating age-period-cohort (APC) effects on the hazard function of death from cancer was developed. In the first step, the procedure estimates the influence of joint APC effects on the hazard function, using Cox PH regression procedures from a standard software package. In the second step, the coefficients for age at diagnosis, time period and birth cohort effects are estimated. To solve the identifiabili...

  20. Functional status, time to transplantation, and survival benefit of kidney transplantation among wait-listed candidates.

    Science.gov (United States)

    Reese, Peter P; Shults, Justine; Bloom, Roy D; Mussell, Adam; Harhay, Meera N; Abt, Peter; Levine, Matthew; Johansen, Kirsten L; Karlawish, Jason T; Feldman, Harold I

    2015-11-01

    In the context of an aging end-stage renal disease population with multiple comorbid conditions, transplantation professionals face challenges in evaluating the global health of patients awaiting kidney transplantation. Functional status might be useful for identifying which patients will derive a survival benefit from transplantation versus dialysis. Retrospective cohort study of wait-listed patients using data for functional status from a national dialysis provider linked to United Network for Organ Sharing registry data. Adult kidney transplantation candidates added to the waiting list between 2000 and 2006. Physical Functioning scale of the Medical Outcomes Study 36-Item Short Form Health Survey, analyzed as a time-varying covariate. Kidney transplantation; survival benefit of transplantation versus remaining wait-listed. We used multivariable Cox regression to assess the association between physical function with study outcomes. In survival benefit analyses, transplantation status was modeled as a time-varying covariate. The cohort comprised 19,242 kidney transplantation candidates (median age, 51 years; 36% black race) receiving maintenance dialysis. Candidates in the lowest baseline Physical Functioning score quartile were more likely to be inactivated (adjusted HR vs highest quartile, 1.30; 95% CI, 1.21-1.39) and less likely to undergo transplantation (adjusted HR vs highest quartile, 0.64; 95% CI, 0.61-0.68). After transplantation, worse Physical Functioning score was associated with shorter 3-year survival (84% vs 92% for the lowest vs highest function quartiles). However, compared to dialysis, transplantation was associated with a statistically significant survival benefit by 9 months for patients in every function quartile. Functional status is self-reported. Even patients with low function appear to live longer with kidney transplantation versus dialysis. For wait-listed patients, global health measures such as functional status may be more useful in

  1. Estimation of survival rates and abundance of green turtles along the U.S. West Coast

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To determine abundance and survival rates of the east Pacific green turtles in the northern most foraging grounds, the turtle research groups at SWFSC have been...

  2. Consistent Parameter and Transfer Function Estimation using Context Free Grammars

    Science.gov (United States)

    Klotz, Daniel; Herrnegger, Mathew; Schulz, Karsten

    2017-04-01

    This contribution presents a method for the inference of transfer functions for rainfall-runoff models. Here, transfer functions are defined as parametrized (functional) relationships between a set of spatial predictors (e.g. elevation, slope or soil texture) and model parameters. They are ultimately used for estimation of consistent, spatially distributed model parameters from a limited amount of lumped global parameters. Additionally, they provide a straightforward method for parameter extrapolation from one set of basins to another and can even be used to derive parameterizations for multi-scale models [see: Samaniego et al., 2010]. Yet, currently an actual knowledge of the transfer functions is often implicitly assumed. As a matter of fact, for most cases these hypothesized transfer functions can rarely be measured and often remain unknown. Therefore, this contribution presents a general method for the concurrent estimation of the structure of transfer functions and their respective (global) parameters. Note, that by consequence an estimation of the distributed parameters of the rainfall-runoff model is also undertaken. The method combines two steps to achieve this. The first generates different possible transfer functions. The second then estimates the respective global transfer function parameters. The structural estimation of the transfer functions is based on the context free grammar concept. Chomsky first introduced context free grammars in linguistics [Chomsky, 1956]. Since then, they have been widely applied in computer science. But, to the knowledge of the authors, they have so far not been used in hydrology. Therefore, the contribution gives an introduction to context free grammars and shows how they can be constructed and used for the structural inference of transfer functions. This is enabled by new methods from evolutionary computation, such as grammatical evolution [O'Neill, 2001], which make it possible to exploit the constructed grammar as a

  3. Estimating Aggregate Import-Demand Function In Nigeria: A Co ...

    African Journals Online (AJOL)

    This paper investigates the behaviour of Nigeria's aggregate imports between the periods 1980-2005. In the empirical analysis of the aggregate import demand function for Nigeria, cointegration and Error Correction modeling approaches have been used. Our econometric estimates suggest that real GDP largely explains ...

  4. Pedotransfer functions to estimate soil water content at field capacity ...

    Indian Academy of Sciences (India)

    20

    Pedotransfer functions to estimate soil water content at field capacity and permanent wilting point in hot Arid Western India. 1*Priyabrata Santra, 1Mahesh Kumar, 1R N Kumawat, 1D K Painuli, 2K M Hati,. 3G B M Heuvelink and 3N H Batjes. 1ICAR-Central Arid Zone Research Institute (CAZRI), Jopdhpur, Rajasthan, India ...

  5. Physical training is beneficial to functional status and survival in patients with prolonged mechanical ventilation

    Directory of Open Access Journals (Sweden)

    Shiauyee Chen

    2011-09-01

    Conclusion: Six weeks physical therapy training plus 6 weeks unsupervised maintenance exercise enhanced functional levels and increased survival for the PMV patients compared with those with no such intervention. Early physical therapy interventions are needed for the PMV patients in respiratory care centers. [J Formos Med Assoc 2011; 110(X:XX–XX

  6. Flexible parametric modelling of cause-specific hazards to estimate cumulative incidence functions

    Science.gov (United States)

    2013-01-01

    Background Competing risks are a common occurrence in survival analysis. They arise when a patient is at risk of more than one mutually exclusive event, such as death from different causes, and the occurrence of one of these may prevent any other event from ever happening. Methods There are two main approaches to modelling competing risks: the first is to model the cause-specific hazards and transform these to the cumulative incidence function; the second is to model directly on a transformation of the cumulative incidence function. We focus on the first approach in this paper. This paper advocates the use of the flexible parametric survival model in this competing risk framework. Results An illustrative example on the survival of breast cancer patients has shown that the flexible parametric proportional hazards model has almost perfect agreement with the Cox proportional hazards model. However, the large epidemiological data set used here shows clear evidence of non-proportional hazards. The flexible parametric model is able to adequately account for these through the incorporation of time-dependent effects. Conclusion A key advantage of using this approach is that smooth estimates of both the cause-specific hazard rates and the cumulative incidence functions can be obtained. It is also relatively easy to incorporate time-dependent effects which are commonly seen in epidemiological studies. PMID:23384310

  7. Effects of matrix- and capsulemodification of the functional survival of microencapsulated Langerhans-islets in vitro

    OpenAIRE

    Horsten, Axel von

    2010-01-01

    Despite insulin therapy transplantation of immunoisolated islets of Langerhans is investigated as treatment for type 1 diabetes. However oxygen supply plays a crucial role for graft survival and function. In previous studies we could demonstrate, that immobilized hemoglobin inside the capsule matrix leads to a significantly increased function and viability of microencapsulated islets. Because a more efficient oxygen supply caused by hemoglobin could be excluded, the present study investigat...

  8. [Survival functions and life tables at the origins of actuarial mathematics].

    Science.gov (United States)

    Spelta, D

    1997-01-01

    "In the determination of death probabilities of an insured subject one can use either statistical data or a mathematical function. In this paper a survey of the relationship between mortality tables and survival functions from the origins until the first half of the nineteenth century is presented. The author has tried to find the methodological grounds which have induced the actuaries to prefer either of these tools." (EXCERPT)

  9. On Estimation of the CES Production Function - Revisited

    DEFF Research Database (Denmark)

    Henningsen, Arne; Henningsen, Geraldine

    2012-01-01

    Estimation of the non-linear Constant Elasticity of Scale (CES) function is generally considered problematic due to convergence problems and unstable and/or meaningless results. These problems often arise from a non-smooth objective function with large flat areas, the discontinuity of the CES fun...... function where the elasticity of substitution is one, and possibly significant rounding errors where the elasticity of substitution is close to one. We suggest three (combinable) solutions that alleviate these problems and improve the reliability and stability of the results....

  10. Efficient Estimation of Nonparametric Genetic Risk Function with Censored Data.

    Science.gov (United States)

    Wang, Yuanjia; Liang, Baosheng; Tong, Xingwei; Marder, Karen; Bressman, Susan; Orr-Urtreger, Avi; Giladi, Nir; Zeng, Donglin

    2015-09-01

    With an increasing number of causal genes discovered for complex human disorders, it is crucial to assess the genetic risk of disease onset for individuals who are carriers of these causal mutations and compare the distribution of age-at-onset with that in non-carriers. In many genetic epidemiological studies aiming at estimating causal gene effect on disease, the age-at-onset of disease is subject to censoring. In addition, some individuals' mutation carrier or non-carrier status can be unknown due to the high cost of in-person ascertainment to collect DNA samples or death in older individuals. Instead, the probability of these individuals' mutation status can be obtained from various sources. When mutation status is missing, the available data take the form of censored mixture data. Recently, various methods have been proposed for risk estimation from such data, but none is efficient for estimating a nonparametric distribution. We propose a fully efficient sieve maximum likelihood estimation method, in which we estimate the logarithm of the hazard ratio between genetic mutation groups using B-splines, while applying nonparametric maximum likelihood estimation for the reference baseline hazard function. Our estimator can be calculated via an expectation-maximization algorithm which is much faster than existing methods. We show that our estimator is consistent and semiparametrically efficient and establish its asymptotic distribution. Simulation studies demonstrate superior performance of the proposed method, which is applied to the estimation of the distribution of the age-at-onset of Parkinson's disease for carriers of mutations in the leucine-rich repeat kinase 2 gene.

  11. Acidosis overrides oxygen deprivation to maintain mitochondrial function and cell survival

    Science.gov (United States)

    Khacho, Mireille; Tarabay, Michelle; Patten, David; Khacho, Pamela; MacLaurin, Jason G.; Guadagno, Jennifer; Bergeron, Richard; Cregan, Sean P.; Harper, Mary-Ellen; Park, David S.; Slack, Ruth S.

    2014-01-01

    Sustained cellular function and viability of high-energy demanding post-mitotic cells rely on the continuous supply of ATP. The utilization of mitochondrial oxidative phosphorylation for efficient ATP generation is a function of oxygen levels. As such, oxygen deprivation, in physiological or pathological settings, has profound effects on cell metabolism and survival. Here we show that mild extracellular acidosis, a physiological consequence of anaerobic metabolism, can reprogramme the mitochondrial metabolic pathway to preserve efficient ATP production regardless of oxygen levels. Acidosis initiates a rapid and reversible homeostatic programme that restructures mitochondria, by regulating mitochondrial dynamics and cristae architecture, to reconfigure mitochondrial efficiency, maintain mitochondrial function and cell survival. Preventing mitochondrial remodelling results in mitochondrial dysfunction, fragmentation and cell death. Our findings challenge the notion that oxygen availability is a key limiting factor in oxidative metabolism and brings forth the concept that mitochondrial morphology can dictate the bioenergetic status of post-mitotic cells. PMID:24686499

  12. Estimation of total genetic effects for survival time in crossbred laying hens showing cannibalism, using pedigree or genomic information.

    Science.gov (United States)

    Brinker, T; Raymond, B; Bijma, P; Vereijken, A; Ellen, E D

    2017-02-01

    Mortality of laying hens due to cannibalism is a major problem in the egg-laying industry. Survival depends on two genetic effects: the direct genetic effect of the individual itself (DGE) and the indirect genetic effects of its group mates (IGE). For hens housed in sire-family groups, DGE and IGE cannot be estimated using pedigree information, but the combined effect of DGE and IGE is estimated in the total breeding value (TBV). Genomic information provides information on actual genetic relationships between individuals and might be a tool to improve TBV accuracy. We investigated whether genomic information of the sire increased TBV accuracy compared with pedigree information, and we estimated genetic parameters for survival time. A sire model with pedigree information (BLUP) and a sire model with genomic information (ssGBLUP) were used. We used survival time records of 7290 crossbred offspring with intact beaks from four crosses. Cross-validation was used to compare the models. Using ssGBLUP did not improve TBV accuracy compared with BLUP which is probably due to the limited number of sires available per cross (~50). Genetic parameter estimates were similar for BLUP and ssGBLUP. For both BLUP and ssGBLUP, total heritable variance (T(2) ), expressed as a proportion of phenotypic variance, ranged from 0.03 ± 0.04 to 0.25 ± 0.09. Further research is needed on breeding value estimation for socially affected traits measured on individuals kept in single-family groups. © 2016 The Authors. Journal of Animal Breeding and Genetics Published by Blackwell Verlag GmbH.

  13. Seasonal survival estimation for a long-distance migratory bird and the influence of winter precipitation

    Science.gov (United States)

    Sarah M. Rockwell; Joseph M. Wunderle; T. Scott Sillett; Carol I. Bocetti; David N. Ewert; Dave Currie; Jennifer D. White; Peter P. Marra

    2017-01-01

    Conservation of migratory animals requires information about seasonal survival rates. Identifying factors that limit populations, and the portions of the annual cycle in which they occur, are critical for recognizing and reducing potential threats. However, such data are lacking for virtually all migratory taxa. We investigated patterns and environmental correlates of...

  14. The impact of frailty on functional survival in patients 1 year after cardiac surgery.

    Science.gov (United States)

    Lytwyn, James; Stammers, Andrew N; Kehler, D Scott; Jung, Patrick; Alexander, Bryce; Hiebert, Brett M; Dubiel, Chris; Kimber, Dustin; Hamm, Naomi; Clarke, Mekayla; Fraser, Carly; Pedreira, Brittany; Duhamel, Todd A; Tangri, Navdeep; Arora, Rakesh C

    2017-12-01

    This study determined whether frailty provides incremental value to the European System for Cardiac Operative Risk Evaluation II in identifying patients at risk of poor 1-year functional survival. This prospective study in patients undergoing cardiac surgery defined frailty using 3 common definitions: (1) the Modified Fried Criteria; (2) the Short Physical Performance Battery; and (3) the Clinical Frailty Scale. The primary outcome was functional survival, defined as being alive at 1 year postsurgery with a health-related quality of life score greater than 60 on the EuroQol-Visual Analogue Scale. Of the 188 participants, 49.5%, 52.6%, and 31.9% were deemed frail according to the Modified Fried Criteria, Short Physical Performance Battery, and Clinical Frailty Scale, respectively. The median age of our cohort was 71.0 years (29.3% female). The probability of functional survival at 1 year for the entire cohort was 73.9%. After adjusting for the European System for Cardiac Operative Risk Evaluation II, patients deemed frail under the Modified Fried Criteria, Short Physical Performance Battery, and Clinical Frailty Scale had an increased odds ratio for poor functional survival of 3.44, 3.47, and 2.08, respectively. When compared with the European System for Cardiac Operative Risk Evaluation II alone, the Modified Fried Criteria, Short Physical Performance Battery, and Clinical Frailty Scale showed an absolute improvement in the discrimination slope of 6.7%, 6.5%, and 2.4% with a category-free classification improvement of 59.6%, 59.2%, and 35.1%, respectively. Preoperative frailty was associated with a 2- to 3.5-fold higher risk of poor functional survival 1 year after cardiac surgery. The addition of frailty to the European System for Cardiac Operative Risk Evaluation II provides incremental value in identifying patients at risk of poor functional survival 1 year postsurgery, regardless of frailty definition. Copyright © 2017 The American Association for

  15. Cancer Prevalence in Aichi, Japan for 2012: Estimates Based on Incidence and Survival Data from Population-Based Cancer Registries

    Science.gov (United States)

    Nakagawa-Senda, Hiroko; Yamaguchi, Michiyo; Matsuda, Tomohiro; Koide, Kayoko; Kondo, Yoshinobu; Tanaka, Hideo; Ito, Hidemi

    2017-08-27

    Background: Cancer is the leading cause of death among both men and women in Japan. Monitoring cancer prevalence is important because prevalence data play a critical role in the development and implementation of health policy. We estimated cancer prevalence in 2012 based on cancer incidence and 5-year survival rate in Aichi Prefecture using data from a population-based cancer registry, the Aichi Cancer Registry, which covers 7.4 million people. Methods: The annual number of incident cases between 2008 and 2012 was used. Survival data of patients diagnosed in 2006–2008 and followed up until the end of 2012 were selected for survival analysis. Cancer prevalence was estimated from incidence and year-specific survival probabilities. Cancer prevalence was stratified by sex, cancer site (25 major cancers), and age group at diagnosis. Results: The estimated prevalence for all cancers in 2012 was 68,013 cases among men, 52,490 cases among women, with 120,503 cases for both sexes. Colorectal cancer was the most incident cancer with 6,654 cases, accounting for 16.0% of overall incident cases, followed by stomach cancer with 5,749 cases (13.8%) and lung cancer with 5,593 cases (13.4%). Prostate cancer was the most prevalent among men, accounting for 21.5%, followed by colorectal and stomach cancers. Breast cancer was the most prevalent among women, accounting for 28.6%, followed by colorectal, stomach, and uterine cancers. Conclusion: This study provides cancer prevalence data that could serve as useful essential information for local governments in cancer management, to carry out more practical and reasonable countermeasures for cancer. Creative Commons Attribution License

  16. Survival analysis: A consumer-friendly method to estimate the optimum sucrose level in probiotic petit suisse.

    Science.gov (United States)

    Esmerino, E A; Paixão, J A; Cruz, A G; Garitta, L; Hough, G; Bolini, H M A

    2015-11-01

    For years, just-about-right (JAR) scales have been among the most used techniques to obtain sensory information about consumer perception, but recently, some researchers have harshly criticized the technique. The present study aimed to apply survival analysis to estimate the optimum sucrose concentration in probiotic petit suisse cheese and compare the survival analysis to JAR scales to verify which technique more accurately predicted the optimum sucrose concentration according to consumer acceptability. Two panels of consumers (total=170) performed affective tests to determine the optimal concentration of sucrose in probiotic petit suisse using 2 different methods of analysis: JAR scales (n=85) and survival analysis (n=85). Then an acceptance test was conducted using naïve consumers (n=100) between 18 and 60 yr old, with 2 samples of petit suisse, one with the ideal sucrose determined by JAR scales and the other with the ideal sucrose content determined by survival analysis, to determine which formulation was in accordance with consumer acceptability. The results indicate that the 2 sensory methods were equally effective in predicting the optimum sucrose level in probiotic petit suisse cheese, and no significant differences were detected in any of the characteristics related to liking evaluated. However, survival analysis has important advantages over the JAR scales. Survival analysis has shown the potential to be an advantageous tool for dairy companies because it was able to accurately predict the optimum sucrose content in a consumer-friendly way and was also practical for researchers because experimental sensory work is simpler and has been shown to be more cost effective than JAR scales without losses of consumer acceptability. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  17. Impaired kidney function at hospital discharge and long-term renal and overall survival in patients who received CRRT.

    Science.gov (United States)

    Stads, Susanne; Fortrie, Gijs; van Bommel, Jasper; Zietse, Robert; Betjes, Michiel G H

    2013-08-01

    Critically ill patients with AKI necessitating renal replacement therapy (RRT) have high in-hospital mortality, and survivors are at risk for kidney dysfunction at hospital discharge. The objective was to evaluate the association between impaired kidney function at hospital discharge with long-term renal and overall survival. Degree of kidney dysfunction in relation to long-term effects on renal survival and patient mortality was investigated in a retrospective cohort study of 1220 adults admitted to an intensive care unit who received continuous RRT between 1994 and 2010. After hospital discharge, median follow-up of survivors (n=475) was 8.5 years (range, 1-17 years); overall mortality rate was 75%. Only 170 (35%) patients were discharged with an estimated GFR (eGFR) >60 ml/min per 1.73 m(2). Multivariate proportional hazards regression analysis demonstrated that age, nonsurgical type of admission, preexisting kidney disease, malignancy, and eGFR of 29-15 ml/min per 1.73 m(2) (hazard ratio [HR], 1.62; 95% confidence interval [CI], 1.01 to 2.58) and eGFR <15 ml/min per 1.73 m(2) (HR, 1.93; 95% CI, 1.23 to 3.02) at discharge were independent predictors of increased mortality. Renal survival was significantly associated with degree of kidney dysfunction at discharge. An eGFR of 29-15 ml/min per 1.73 m(2) (HR, 26.26; 95% CI, 5.59 to 123.40) and <15 ml/min per 1.73 m(2) (HR, 172.28; 95% CI, 37.72 to 786.75) were independent risk factors for initiation of long-term RRT. Most critically ill patients surviving AKI necessitating RRT have impaired kidney function at hospital discharge. An eGFR <30 ml/min per 1.73 m(2) is a strong risk factor for decreased long-term survival and poor renal survival.

  18. Local Linear Density Estimation for Filtered Survival Data with Bias Correction

    DEFF Research Database (Denmark)

    Tanggaard, Carsten; Nielsen, Jens Perch; Jones, M.C.

    A class of local linear kernel density estimators based on weighted least squares kernel estimation is considered within the framework of Aalen's multiplicative intensity model. This model includes the filtered data model that, in turn, allows for truncation and/or censoring in addition to accomm...... within our framework. The multiplicative bias correction method proves to be best in a simulation study comparing the performance of the considered estimators. An example concerning old age mortality demonstrates the importance of the improvements provided....

  19. Joint brain connectivity estimation from diffusion and functional MRI data

    Science.gov (United States)

    Chu, Shu-Hsien; Lenglet, Christophe; Parhi, Keshab K.

    2015-03-01

    Estimating brain wiring patterns is critical to better understand the brain organization and function. Anatomical brain connectivity models axonal pathways, while the functional brain connectivity characterizes the statistical dependencies and correlation between the activities of various brain regions. The synchronization of brain activity can be inferred through the variation of blood-oxygen-level dependent (BOLD) signal from functional MRI (fMRI) and the neural connections can be estimated using tractography from diffusion MRI (dMRI). Functional connections between brain regions are supported by anatomical connections, and the synchronization of brain activities arises through sharing of information in the form of electro-chemical signals on axon pathways. Jointly modeling fMRI and dMRI data may improve the accuracy in constructing anatomical connectivity as well as functional connectivity. Such an approach may lead to novel multimodal biomarkers potentially able to better capture functional and anatomical connectivity variations. We present a novel brain network model which jointly models the dMRI and fMRI data to improve the anatomical connectivity estimation and extract the anatomical subnetworks associated with specific functional modes by constraining the anatomical connections as structural supports to the functional connections. The key idea is similar to a multi-commodity flow optimization problem that minimizes the cost or maximizes the efficiency for flow configuration and simultaneously fulfills the supply-demand constraint for each commodity. In the proposed network, the nodes represent the grey matter (GM) regions providing brain functionality, and the links represent white matter (WM) fiber bundles connecting those regions and delivering information. The commodities can be thought of as the information corresponding to brain activity patterns as obtained for instance by independent component analysis (ICA) of fMRI data. The concept of information

  20. Pro-survival function of MEF2 in cardiomyocytes is enhanced by β-blockers

    Science.gov (United States)

    Hashemi, S; Salma, J; Wales, S; McDermott, JC

    2015-01-01

    β1-Adrenergic receptor (β1-AR) stimulation increases apoptosis in cardiomyocytes through activation of cAMP/protein kinase A (PKA) signaling. The myocyte enhancer factor 2 (MEF2) proteins function as important regulators of myocardial gene expression. Previously, we reported that PKA signaling directly represses MEF2 activity. We determined whether (a) MEF2 has a pro-survival function in cardiomyocytes, and (b) whether β-adrenergic/PKA signaling modulates MEF2 function in cardiomyocytes. Initially, we observed that siRNA-mediated gene silencing of MEF2 induces cardiomyocyte apoptosis as indicated by flow cytometry. β1-AR activation by isoproterenol represses MEF2 activity and promotes apoptosis in cultured neonatal cardiomyocytes. Importantly, β1-AR mediated apoptosis was abrogated in cardiomyocytes expressing a PKA-resistant form of MEF2D (S121/190A). We also observed that a β1-blocker, Atenolol, antagonizes isoproterenol-induced apoptosis while concomitantly enhancing MEF2 transcriptional activity. β-AR stimulation modulated MEF2 cellular localization in cardiomyocytes and this effect was reversed by β-blocker treatment. Furthermore, Kruppel-like factor 6, a MEF2 target gene in the heart, functions as a downstream pro-survival factor in cardiomyocytes. Collectively, these data indicate that (a) MEF2 has an important pro-survival role in cardiomyocytes, and (b) β-adrenergic signaling antagonizes the pro-survival function of MEF2 in cardiomyocytes and β-blockers promote it. These observations have important clinical implications that may contribute to novel strategies for preventing cardiomyocyte apoptosis associated with heart pathology. PMID:27551452

  1. Nonparametric estimation of the maximum of conditional hazard function under dependence conditions for functional data

    OpenAIRE

    Abbes Rabhi, Abbes; Hammou, Yassine; Djebbouri, Tayeb

    2015-01-01

    The maximum of the conditional hazard function is a parameter of great importance in seismicity studies, because it constitutes the maximum risk of occurrence of an earthquake in a given interval of time. using the kernel nonparametric estimates of the first derivative of the conditional hazard function, we establish uniform convergence properties and asymptotic normality of an estimate of the maximum in the context of strong mixing dependence.

  2. Unbiased survival estimates and evidence for skipped breeding opportunities in females

    Science.gov (United States)

    Muths, Erin L.; Scherer, Rick D.; Lambert, Brad A.

    2010-01-01

    1. Estimates of demographic parameters for females, in many organisms, are sparse. This is particularly worrisome as more and more species are faced with high extinction probabilities and conservation increasingly depends on actions dictated by complex predictive models that require accurate estimates of demographic parameters for each sex and species.

  3. Estimating Probability of Default on Peer to Peer Market – Survival Analysis Approach

    Directory of Open Access Journals (Sweden)

    Đurović Andrija

    2017-05-01

    Full Text Available Arguably a cornerstone of credit risk modelling is the probability of default. This article aims is to search for the evidence of relationship between loan characteristics and probability of default on peer-to-peer (P2P market. In line with that, two loan characteristics are analysed: 1 loan term length and 2 loan purpose. The analysis is conducted using survival analysis approach within the vintage framework. Firstly, 12 months probability of default through the cycle is used to compare riskiness of analysed loan characteristics. Secondly, log-rank test is employed in order to compare complete survival period of cohorts. Findings of the paper suggest that there is clear evidence of relationship between analysed loan characteristics and probability of default. Longer term loans are more risky than the shorter term ones and the least risky loans are those used for credit card payoff.

  4. Best lung function equations for the very elderly selected by survival analysis

    DEFF Research Database (Denmark)

    Miller, Martin R; Thinggaard, Mikael; Christensen, Kaare

    2014-01-01

    proportional hazard regression found lower FEV1SR was a predictor of mortality having controlled for MMSE, grip strength and sex. The US National Health and Nutrition Examination Survey (NHANES) III (1999) equations gave a better spread of median survival by FEV1SR quartile: 3.94, 3.65, 3.51 and 2.61 years...... with a hazard ratio for death of 1, 1.16, 1.32 and 1.60 respectively, compared with equations derived with the inclusion of elderly subjects.We conclude that extrapolating from NHANES III equations to predict lung function in nonagenarians gave better survival predictions from spirometry than when employing...... equations derived using very elderly subjects with possible selection bias. These findings can help inform how future lung function equations for the elderly are derived....

  5. Machine Learning Estimation of Atom Condensed Fukui Functions.

    Science.gov (United States)

    Zhang, Qingyou; Zheng, Fangfang; Zhao, Tanfeng; Qu, Xiaohui; Aires-de-Sousa, João

    2016-02-01

    To enable the fast estimation of atom condensed Fukui functions, machine learning algorithms were trained with databases of DFT pre-calculated values for ca. 23,000 atoms in organic molecules. The problem was approached as the ranking of atom types with the Bradley-Terry (BT) model, and as the regression of the Fukui function. Random Forests (RF) were trained to predict the condensed Fukui function, to rank atoms in a molecule, and to classify atoms as high/low Fukui function. Atomic descriptors were based on counts of atom types in spheres around the kernel atom. The BT coefficients assigned to atom types enabled the identification (93-94 % accuracy) of the atom with the highest Fukui function in pairs of atoms in the same molecule with differences ≥0.1. In whole molecules, the atom with the top Fukui function could be recognized in ca. 50 % of the cases and, on the average, about 3 of the top 4 atoms could be recognized in a shortlist of 4. Regression RF yielded predictions for test sets with R(2) =0.68-0.69, improving the ability of BT coefficients to rank atoms in a molecule. Atom classification (as high/low Fukui function) was obtained with RF with sensitivity of 55-61 % and specificity of 94-95 %. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Osteocalcin protects pancreatic beta cell function and survival under high glucose conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kover, Karen, E-mail: kkover@cmh.edu [Division of Endocrine/Diabetes, Children' s Mercy Hospital & Clinics, Kansas City, MO 64108 (United States); University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108 (United States); Yan, Yun; Tong, Pei Ying; Watkins, Dara; Li, Xiaoyu [Division of Endocrine/Diabetes, Children' s Mercy Hospital & Clinics, Kansas City, MO 64108 (United States); University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108 (United States); Tasch, James; Hager, Melissa [Kansas City University Medical Biosciences, Kansas City, MO (United States); Clements, Mark; Moore, Wayne V. [Division of Endocrine/Diabetes, Children' s Mercy Hospital & Clinics, Kansas City, MO 64108 (United States); University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108 (United States)

    2015-06-19

    Diabetes is characterized by progressive beta cell dysfunction and loss due in part to oxidative stress that occurs from gluco/lipotoxicity. Treatments that directly protect beta cell function and survival in the diabetic milieu are of particular interest. A growing body of evidence suggests that osteocalcin, an abundant non-collagenous protein of bone, supports beta cell function and proliferation. Based on previous gene expression data by microarray, we hypothesized that osteocalcin protects beta cells from glucose-induced oxidative stress. To test our hypothesis we cultured isolated rat islets and INS-1E cells in the presence of normal, high, or high glucose ± osteocalcin for up to 72 h. Oxidative stress and viability/mitochondrial function were measured by H{sub 2}O{sub 2} assay and Alamar Blue assay, respectively. Caspase 3/7 activity was also measured as a marker of apoptosis. A functional test, glucose stimulated insulin release, was conducted and expression of genes/protein was measured by qRT-PCR/western blot/ELISA. Osteocalcin treatment significantly reduced high glucose-induced H{sub 2}O{sub 2} levels while maintaining viability/mitochondrial function. Osteocalcin also significantly improved glucose stimulated insulin secretion and insulin content in rat islets after 48 h of high glucose exposure compared to untreated islets. As expected sustained high glucose down-regulated gene/protein expression of INS1 and BCL2 while increasing TXNIP expression. Interestingly, osteocalcin treatment reversed the effects of high glucose on gene/protein expression. We conclude that osteocalcin can protect beta cells from the negative effects of glucose-induced oxidative stress, in part, by reducing TXNIP expression, thereby preserving beta cell function and survival. - Highlights: • Osteocalcin reduces glucose-induced oxidative stress in beta cells. • Osteocalcin preserves beta cell function and survival under stress conditions. • Osteocalcin reduces glucose

  7. IL-7 Promotes T Cell Viability, Trafficking, and Functionality and Improves Survival in Sepsis

    OpenAIRE

    Unsinger, Jacqueline; McGlynn, Margaret; Kasten, Kevin R.; Hoekzema, Andrew S.; Watanabe, Eizo; Muenzer, Jared T.; McDonough, Jacquelyn S.; Tschoep, Johannes; Ferguson, Thomas A.; McDunn, Jonathan E.; Morre, Michel; Hildeman, David A.; Caldwell, Charles C.; Hotchkiss, Richard S.

    2010-01-01

    Sepsis is a highly lethal disorder characterized by widespread apoptosis-induced depletion of immune cells and the development of a profound immunosuppressive state. IL-7 is a potent antiapoptotic cytokine that enhances immune effector cell function and is essential for lymphocyte survival. In this study, recombinant human IL-7 (rhIL-7) efficacy and potential mechanisms of action were tested in a murine peritonitis model. Studies at two independent laboratories showed that rhIL-7 markedly imp...

  8. Blocking LINGO-1 function promotes retinal ganglion cell survival following ocular hypertension and optic nerve transection.

    Science.gov (United States)

    Fu, Qing-Ling; Hu, Bing; Wu, Wutian; Pepinsky, R Blake; Mi, Sha; So, Kwok-Fai

    2008-03-01

    LINGO-1 is a functional member of the Nogo66 receptor (NgR1)/p75 and NgR1/TROY signaling complexes that prevent axonal regeneration through RhoA in the central nervous system. LINGO-1 also promotes cell death after neuronal injury and spinal cord injury. The authors sought to examine whether blocking LINGO-1 function with LINGO-1 antagonists promotes retinal ganglion cell (RGC) survival after ocular hypertension and optic nerve transection. An experimental ocular hypertension model was induced in adult rats using an argon laser to photocoagulate the episcleral and limbal veins. LINGO-1 expression in the retinas was investigated using immunohistochemistry and Western blotting. Soluble LINGO-1 protein (LINGO-1-Fc) and anti-LINGO-1 mAb 1A7 were injected into the vitreous body to examine their effects on RGC survival after ocular hypertension and optic nerve transection. Signal transduction pathways mediating neuroprotective LINGO-1-Fc effects were characterized using Western blotting and specific kinase inhibitors. LINGO-1 was expressed in RGCs and up-regulated after intraocular pressure elevation. Blocking LINGO-1 function with LINGO-1 antagonists, LINGO-1-Fc and 1A7 significantly reduced RGC loss 2 and 4 weeks after ocular hypertension and also promoted RGC survival after optic nerve transection. LINGO-1-Fc treatment blocked the RhoA, JNK pathway and promoted Akt activation. LINGO-1-Fc induced Akt phosphorylation, and the survival effect of LINGO-1 antagonists was abolished by Akt phosphorylation inhibitor. The authors demonstrated that blocking LINGO-1 function with LINGO-1 antagonists rescues RGCs from cell death after ocular hypertension and optic nerve transection. They also delineated the RhoA and PI-3K/Akt pathways as the predominant mediator of LINGO-1-Fc neuroprotection in this paradigm of RGC death.

  9. Local linear density estimation for filtered survival data, with bias correction

    DEFF Research Database (Denmark)

    Nielsen, Jens Perch; Tanggaard, Carsten; Jones, M.C.

    2009-01-01

    A class of local linear kernel density estimators based on weighted least-squares kernel estimation is considered within the framework of Aalen's multiplicative intensity model. This model includes the filtered data model that, in turn, allows for truncation and/or censoring in addition to accomm...... within our framework. The multiplicative bias-correction method proves to be the best in a simulation study comparing the performance of the considered estimators. An example concerning old-age mortality demonstrates the importance of the improvements provided....

  10. Survival Estimates for the Passage of Juvenile Salmonids through Snake River Dams and Reservoirs, 1997 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Hockersmith, Eric E.

    1999-03-01

    This report consists of two parts describing research activities completed during 1997 under Bonneville Power Administration Project Number 93-29. Part 1 provides reach survival and travel time estimates for 1997 for PIT-tagged hatchery steelhead and yearling chinook salmon in the Snake and Columbia Rivers. The results are reported primarily in the form of tables and figures with a minimum of text. More detailed information on methodology and the statistical models used in the analysis are provided in previous annual reports cited in the text. Analysis of the relationships among travel time, survival, and environmental factors for 1997 and previous years of the study will be reported elsewhere. Part 2 of this report describes research to determine areas of loss and delay for juvenile hatchery salmonids above Lower Granite Reservoir.

  11. Pre-transplant lung function is predictive of survival following pediatric bone marrow transplantation.

    Science.gov (United States)

    Ginsberg, Jill P; Aplenc, Richard; McDonough, Joseph; Bethel, James; Doyle, John; Weiner, Daniel J

    2010-03-01

    Pulmonary toxicity is well described in recipients of bone marrow transplants (BMT), and accounts for a sizeable proportion of post-transplant mortality. The majority of the data on post-transplant pulmonary function is from adults, although several small pediatric case series have been described. In adults, pre-transplant lung function has been predictive of post-transplant respiratory failure and mortality. This use of pulmonary function testing, that is, for pre-transplant risk counseling, is novel but has never been applied to pediatric patients. We hypothesized that in children, as in adults, pre-transplant pulmonary function would also be predictive of outcome post-transplantation morbidity. Retrospective database analysis of pulmonary function tests of patients undergoing first myeloablative BMT at two large children's hospitals. Two hundred seventy-three subjects had at least one pre-transplant PFT, and 317 subjects had at least one post-transplant PFT available for analysis. While the majority of patients had normal or mildly reduced pre-transplant flows and lung volume, 25% had moderately or severely reduced diffusion. All lung function parameters decreased post-transplant with a slow improvement over ensuing years. The Lung Function Score, a combined measurement of FEV(1) and DLCO, was highly associated with post-transplant survival. Hazard ratios for mortality (compared to the best LFS) ranged from 1.654 to 2.454. Lung function prior to bone marrow transplant, especially diffusing capacity, is frequently abnormal. Lung function frequently decreases shortly post-transplant and tends to improve over time, but frequently remains abnormal even years after transplant. Post-transplant survival is related to pre-transplant lung function. Copyright 2009 Wiley-Liss, Inc.

  12. Joint nonparametric correction estimator for excess relative risk regression in survival analysis with exposure measurement error.

    Science.gov (United States)

    Wang, Ching-Yun; Cullings, Harry; Song, Xiao; Kopecky, Kenneth J

    2017-11-01

    Observational epidemiological studies often confront the problem of estimating exposure-disease relationships when the exposure is not measured exactly. In the paper, we investigate exposure measurement error in excess relative risk regression, which is a widely used model in radiation exposure effect research. In the study cohort, a surrogate variable is available for the true unobserved exposure variable. The surrogate variable satisfies a generalized version of the classical additive measurement error model, but it may or may not have repeated measurements. In addition, an instrumental variable is available for individuals in a subset of the whole cohort. We develop a nonparametric correction (NPC) estimator using data from the subcohort, and further propose a joint nonparametric correction (JNPC) estimator using all observed data to adjust for exposure measurement error. An optimal linear combination estimator of JNPC and NPC is further developed. The proposed estimators are nonparametric, which are consistent without imposing a covariate or error distribution, and are robust to heteroscedastic errors. Finite sample performance is examined via a simulation study. We apply the developed methods to data from the Radiation Effects Research Foundation, in which chromosome aberration is used to adjust for the effects of radiation dose measurement error on the estimation of radiation dose responses.

  13. Effect of somatic cell count level on functional longevity in Valle del Belice dairy sheep assessed using survival analysis.

    Science.gov (United States)

    Riggio, V; Maizon, D O; Portolano, B; Bovenhuis, H; van Arendonk, J A M

    2009-12-01

    The objectives of this study were to evaluate the effect of somatic cell count (SCC) on functional longevity and to estimate the heritability of functional longevity using survival analysis in Valle del Belice dairy sheep. A total of 4,880 lactations of 2,190 ewes from 11 flocks were used. In this study, SCC was considered as an indication of subclinical mastitis. In case of clinical cases, identified by the technicians at milking time, test-day weights and milk samples of those ewes were not considered. Somatic cells were analyzed as counts, without any transformation, and were grouped in 3 classes based on the observed SCC maximum (mxSCC). The mxSCC classes, expressed as 10(3) cells/mL, were classified as 1 if mxSCC or= 1,000. An increase in SCC was associated with an increased hazard of being culled. Ewes in the highest class of SCC on a test-day had a 20% higher hazard of being culled than those in the lowest class. Therefore, SCC played a role in culling decisions of Valle del Belice dairy sheep farmers. The heritability estimate for functional longevity was 7% on the logarithmic scale and 11% on the real scale, indicating that selection for this trait is possible in sheep. The flock-year-season effect explained 19% of the variation on the logarithmic scale and 27% of the variation on the real scale.

  14. Power estimation on functional level for programmable processors

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2004-01-01

    Full Text Available In diesem Beitrag werden verschiedene Ansätze zur Verlustleistungsschätzung von programmierbaren Prozessoren vorgestellt und bezüglich ihrer Übertragbarkeit auf moderne Prozessor-Architekturen wie beispielsweise Very Long Instruction Word (VLIW-Architekturen bewertet. Besonderes Augenmerk liegt hierbei auf dem Konzept der sogenannten Functional-Level Power Analysis (FLPA. Dieser Ansatz basiert auf der Einteilung der Prozessor-Architektur in funktionale Blöcke wie beispielsweise Processing-Unit, Clock-Netzwerk, interner Speicher und andere. Die Verlustleistungsaufnahme dieser Bl¨ocke wird parameterabhängig durch arithmetische Modellfunktionen beschrieben. Durch automatisierte Analyse von Assemblercodes des zu schätzenden Systems mittels eines Parsers können die Eingangsparameter wie beispielsweise der erzielte Parallelitätsgrad oder die Art des Speicherzugriffs gewonnen werden. Dieser Ansatz wird am Beispiel zweier moderner digitaler Signalprozessoren durch eine Vielzahl von Basis-Algorithmen der digitalen Signalverarbeitung evaluiert. Die ermittelten Schätzwerte für die einzelnen Algorithmen werden dabei mit physikalisch gemessenen Werten verglichen. Es ergibt sich ein sehr kleiner maximaler Schätzfehler von 3%. In this contribution different approaches for power estimation for programmable processors are presented and evaluated concerning their capability to be applied to modern digital signal processor architectures like e.g. Very Long InstructionWord (VLIW -architectures. Special emphasis will be laid on the concept of so-called Functional-Level Power Analysis (FLPA. This approach is based on the separation of the processor architecture into functional blocks like e.g. processing unit, clock network, internal memory and others. The power consumption of these blocks is described by parameter dependent arithmetic model functions. By application of a parser based automized analysis of assembler codes of the systems to be estimated

  15. Identification of Sparse Neural Functional Connectivity using Penalized Likelihood Estimation and Basis Functions

    Science.gov (United States)

    Song, Dong; Wang, Haonan; Tu, Catherine Y.; Marmarelis, Vasilis Z.; Hampson, Robert E.; Deadwyler, Sam A.; Berger, Theodore W.

    2013-01-01

    One key problem in computational neuroscience and neural engineering is the identification and modeling of functional connectivity in the brain using spike train data. To reduce model complexity, alleviate overfitting, and thus facilitate model interpretation, sparse representation and estimation of functional connectivity is needed. Sparsities include global sparsity, which captures the sparse connectivities between neurons, and local sparsity, which reflects the active temporal ranges of the input-output dynamical interactions. In this paper, we formulate a generalized functional additive model (GFAM) and develop the associated penalized likelihood estimation methods for such a modeling problem. A GFAM consists of a set of basis functions convolving the input signals, and a link function generating the firing probability of the output neuron from the summation of the convolutions weighted by the sought model coefficients. Model sparsities are achieved by using various penalized likelihood estimations and basis functions. Specifically, we introduce two variations of the GFAM using a global basis (e.g., Laguerre basis) and group LASSO estimation, and a local basis (e.g., B-spline basis) and group bridge estimation, respectively. We further develop an optimization method based on quadratic approximation of the likelihood function for the estimation of these models. Simulation and experimental results show that both group-LASSO-Laguerre and group-bridge-B-spline can capture faithfully the global sparsities, while the latter can replicate accurately and simultaneously both global and local sparsities. The sparse models outperform the full models estimated with the standard maximum likelihood method in out-of-sample predictions. PMID:23674048

  16. Prediction of the survival and functional ability of severe stroke patients after ICU therapeutic intervention

    Directory of Open Access Journals (Sweden)

    Aoun-Bacha Zeina

    2008-06-01

    Full Text Available Abstract Background This study evaluated the benefits and impact of ICU therapeutic interventions on the survival and functional ability of severe cerebrovascular accident (CVA patients. Methods Sixty-two ICU patients suffering from severe ischemic/haemorrhagic stroke were evaluated for CVA severity using APACHE II and the Glasgow coma scale (GCS. Survival was determined using Kaplan-Meier survival tables and survival prediction factors were determined by Cox multivariate analysis. Functional ability was assessed using the stroke impact scale (SIS-16 and Karnofsky score. Risk factors, life support techniques and neurosurgical interventions were recorded. One year post-CVA dependency was investigated using multivariate analysis based on linear regression. Results The study cohort constituted 6% of all CVA (37.8% haemorrhagic/62.2% ischemic admissions. Patient mean(SD age was 65.8(12.3 years with a 1:1 male: female ratio. During the study period 16 patients had died within the ICU and seven in the year following hospital release. The mean(SD APACHE II score at hospital admission was 14.9(6.0 and ICU mean duration of stay was 11.2(15.4 days. Mechanical ventilation was required in 37.1% of cases. Risk ratios were; GCS at admission 0.8(0.14, (p = 0.024, APACHE II 1.11(0.11, (p = 0.05 and duration of mechanical ventilation 1.07(0.07, (p = 0.046. Linear coefficients were: type of CVA – haemorrhagic versus ischemic: -18.95(4.58 (p = 0.007, GCS at hospital admission: -6.83(1.08, (p = 0.001, and duration of hospital stay -0.38(0.14, (p = 0.40. Conclusion To ensure a better prognosis CVA patients require ICU therapeutic interventions. However, as we have shown, where tests can determine the worst affected patients with a poor vital and functional outcome should treatment be withheld?

  17. ANP AFFECTS CARDIAC REMODELING, FUNCTION, HEART FAILURE AND SURVIVAL IN A MOUSE MODEL OF DILATED CARDIOMYOPATHY

    Science.gov (United States)

    Wang, Dong; Gladysheva, Inna P.; Fan, Tai-Hwang M.; Sullivan, Ryan; Houng, Aiilyan K.; Reed, Guy L.

    2014-01-01

    Dilated cardiomyopathy is a frequent cause of heart failure and death. Atrial natriuretic peptide (ANP) is a biomarker of dilated cardiomyopathy, but there is controversy whether ANP modulates the development of heart failure. Therefore we examined whether ANP affects heart failure, cardiac remodeling, function and survival in a well-characterized, transgenic model of dilated cardiomyopathy. Mice with dilated cardiomyopathy with normal ANP levels survived longer than mice with partial ANP (pANP deficiency (pANP protected against the development of heart failure as indicated by reduced lung water, alveolar congestion, pleural effusions etc. ANP improved systolic function and reduced cardiomegaly. Pathologic cardiac remodeling was diminished in mice with normal ANP as indicated by decreased ventricular interstitial and perivascular fibrosis. Mice with dilated cardiomyopathy and normal ANP levels had better systolic function (pANP-deficiency. Dilated cardiomyopathy was associated with diminished cardiac transcripts for natriuretic peptide receptors A and B in mice with normal ANP and ANP-deficiency but transcripts for natriuretic peptide receptor C and CNP were selectively altered in mice with dilated cardiomyopathy and ANP-deficiency. Taken together, these data indicate that ANP has potent effects in experimental dilated cardiomyopathy that reduce the development of heart failure, prevent pathologic remodeling, preserve systolic function and reduce mortality. Despite the apparent overlap in physiologic function between the natriuretic peptides, these data suggest that the role of ANP in dilated cardiomyopathy and heart failure is not compensated physiologically by other natriuretic peptides. PMID:24379183

  18. Spectral velocity estimation using autocorrelation functions for sparse data sets

    DEFF Research Database (Denmark)

    2006-01-01

    -mode image for orientation, and data for this has to acquired interleaved with the flow data. The power spectrum can be calculated from the Fourier transform of the autocorrelation function Ry (k), where its span of lags k is given by the number of emission N in the data segment for velocity estimation....... The lag corresponds to the difference in pulse number, so that for lag k data from emission i is correlated with i + k. The autocorrelation for lag k can be averaged over N-k pairs of emissions. It is possible to calculate Ry (k) for a sparse set of emissions, as long as all combinations of emissions...

  19. Bayesian Parameter Estimation via Filtering and Functional Approximations

    KAUST Repository

    Matthies, Hermann G.

    2016-11-25

    The inverse problem of determining parameters in a model by comparing some output of the model with observations is addressed. This is a description for what hat to be done to use the Gauss-Markov-Kalman filter for the Bayesian estimation and updating of parameters in a computational model. This is a filter acting on random variables, and while its Monte Carlo variant --- the Ensemble Kalman Filter (EnKF) --- is fairly straightforward, we subsequently only sketch its implementation with the help of functional representations.

  20. Childhood craniopharyngioma: survival, local control, endocrine and neurologic function following radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Danoff, B.F.; Cowchock, F.S.; Kramer, S.

    1983-02-01

    Between 1961 and 1978, 19 patients with a diagnosis of childhood or teenage craniopharyngioma received supervoltage radiotherapy. All patients had previously undergone either partial surgical resection (10 patients), total gross resection (3 patients), or aspiration and biopsy (6 patients). Fourteen patients were treated primarily and five were treated for recurrence. The five-year survival was 73% with a 10-year survival of 64%. Sixteen percent developed a recurrence following radiotherapy. Long term effects were assesed in terms of neurologic, intellectual, psychological and endocrine function. Seventy-nine percent had none or minimal neurologic disability. The mean full scale IQ for the group was 90. There were no additional endocrine deficiencies that could be directly attributed to radiation. Behavioral disorders occurred in 50%. These results are at least comparable, if not superior, to those of surgery.

  1. Fused Adaptive Lasso for Spatial and Temporal Quantile Function Estimation

    KAUST Repository

    Sun, Ying

    2015-09-01

    Quantile functions are important in characterizing the entire probability distribution of a random variable, especially when the tail of a skewed distribution is of interest. This article introduces new quantile function estimators for spatial and temporal data with a fused adaptive Lasso penalty to accommodate the dependence in space and time. This method penalizes the difference among neighboring quantiles, hence it is desirable for applications with features ordered in time or space without replicated observations. The theoretical properties are investigated and the performances of the proposed methods are evaluated by simulations. The proposed method is applied to particulate matter (PM) data from the Community Multiscale Air Quality (CMAQ) model to characterize the upper quantiles, which are crucial for studying spatial association between PM concentrations and adverse human health effects. © 2016 American Statistical Association and the American Society for Quality.

  2. estimated glomerular filtration rate and risk of survival in acute stroke

    African Journals Online (AJOL)

    2014-03-03

    Mar 3, 2014 ... rate or glomerular filtration barrier and occurrence of stroke. Arch Neurol 2008; 65: 934-938. 2. Matsushita K,Mahmoodi BK, Woodward M,. Emberson JR, Jafar TH, Jee SH et al. Comparison of risk prediction using the CKD-EPI equation and the. MDRD study equation for estimated glomerular filtration rate.

  3. Systematic review of survival time in experimental mouse stroke with impact on reliability of infarct estimation

    DEFF Research Database (Denmark)

    Klarskov, Carina Kirstine; Klarskov, Mikkel Buster; Hasseldam, Henrik

    2016-01-01

    and a comparison of correction methods will be discussed. Method: Relevant terms were searched in the National Library of Medicine PubMed database. A method for classification of infarct measurement methods was made using a naming convention. Conclusion: Our study shows that infarct size estimations are often...

  4. Functional mapping–guided resection of low-grade gliomas in eloquent areas of the brain: improvement of long-term survival

    Science.gov (United States)

    Chang, Edward F.; Clark, Aaron; Smith, Justin S.; Polley, Mei-Yin; Chang, Susan M.; Barbaro, Nicholas M.; Parsa, Andrew T.; McDermott, Michael W.; Berger, Mitchel S.

    2013-01-01

    Object Low-grade gliomas (LGGs) frequently infiltrate highly functional or “eloquent” brain areas. Given the lack of long-term survival data, the prognostic significance of eloquent brain tumor location and the role of functional mapping during resective surgery in presumed eloquent brain regions are unknown. Methods We performed a retrospective analysis of 281 cases involving adults who underwent resection of a supratentorial LGG at a brain tumor referral center. Preoperative MR images were evaluated blindly for involvement of eloquent brain areas, including the sensorimotor and language cortices, and specific subcortical structures. For high-risk tumors located in presumed eloquent brain areas, long-term survival estimates were evaluated for patients who underwent intraoperative functional mapping with electrocortical stimulation and for those who did not. Results One hundred and seventy-four patients (62%) had high-risk LGGs that were located in presumed eloquent areas. Adjusting for other known prognostic factors, patients with tumors in areas presumed to be eloquent had worse overall and progression-free survival (OS, hazard ratio [HR] 6.1, 95% CI 2.6–14.1; PFS, HR 1.9, 95% CI 1.2–2.9; Cox proportional hazards). Confirmation of tumor overlapping functional areas during intraoperative mapping was strongly associated with shorter survival (OS, HR 9.6, 95% CI 3.6–25.9). In contrast, when mapping revealed that tumor spared true eloquent areas, patients had significantly longer survival, nearly comparable to patients with tumors that clearly involved only noneloquent areas, as demonstrated by preoperative imaging (OS, HR 2.9, 95% CI 1.0–8.5). Conclusions Presumed eloquent location of LGGs is an important but modifiable risk factor predicting disease progression and death. Delineation of true functional and nonfunctional areas by intraoperative mapping in high-risk patients to maximize tumor resection can dramatically improve long-term survival. PMID

  5. Rethinking plant functional types in Earth System Models: pan-tropical analysis of tree survival across environmental gradients

    Science.gov (United States)

    Johnson, D. J.; Needham, J.; Xu, C.; Davies, S. J.; Bunyavejchewin, S.; Giardina, C. P.; Condit, R.; Cordell, S.; Litton, C. M.; Hubbell, S.; Kassim, A. R. B.; Shawn, L. K. Y.; Nasardin, M. B.; Ong, P.; Ostertag, R.; Sack, L.; Tan, S. K. S.; Yap, S.; McDowell, N. G.; McMahon, S.

    2016-12-01

    Terrestrial carbon cycling is a function of the growth and survival of trees. Current model representations of tree growth and survival at a global scale rely on coarse plant functional traits that are parameterized very generally. In view of the large biodiversity in the tropical forests, it is important that we account for the functional diversity in order to better predict tropical forest responses to future climate changes. Several next generation Earth System Models are moving towards a size-structured, trait-based approach to modelling vegetation globally, but the challenge of which and how many traits are necessary to capture forest complexity remains. Additionally, the challenge of collecting sufficient trait data to describe the vast species richness of tropical forests is enormous. We propose a more fundamental approach to these problems by characterizing forests by their patterns of survival. We expect our approach to distill real-world tree survival into a reasonable number of functional types. Using 10 large-area tropical forest plots that span geographic, edaphic and climatic gradients, we model tree survival as a function of tree size for hundreds of species. We found surprisingly few categories of size-survival functions emerge. This indicates some fundamental strategies at play across diverse forests to constrain the range of possible size-survival functions. Initial cluster analysis indicates that four to eight functional forms are necessary to describe variation in size-survival relations. Temporal variation in size-survival functions can be related to local environmental variation, allowing us to parameterize how demographically similar groups of species respond to perturbations in the ecosystem. We believe this methodology will yield a synthetic approach to classifying forest systems that will greatly reduce uncertainty and complexity in global vegetation models.

  6. Function of Ltbp-4L and fibulin-4 in survival and elastogenesis in mice

    Directory of Open Access Journals (Sweden)

    Insa Bultmann-Mellin

    2016-11-01

    Full Text Available LTBP-4L and LTBP-4S are two isoforms of the extracellular matrix protein latent-transforming growth factor beta-binding protein 4 (LTBP-4. The mutational inactivation of both isoforms causes autosomal recessive cutis laxa type 1C (ARCL1C in humans and an ARCL1C-like phenotype in Ltbp4−/− mice, both characterized by high postnatal mortality and severely affected elastogenesis. However, genetic data in mice suggest isoform-specific functions for Ltbp-4 because Ltbp4S−/− mice, solely expressing Ltbp-4L, survive to adulthood. This clearly suggests a requirement of Ltbp-4L for postnatal survival. A major difference between Ltbp4S−/− and Ltbp4−/− mice is the matrix incorporation of fibulin-4 (a key factor for elastogenesis; encoded by the Efemp2 gene, which is normal in Ltbp4S−/− mice, whereas it is defective in Ltbp4−/− mice, suggesting that the presence of Ltbp-4L might be required for this process. To investigate the existence of a functional interaction between Ltbp-4L and fibulin-4, we studied the consequences of fibulin-4 deficiency in mice only expressing Ltbp-4L. Resulting Ltbp4S−/−;Fibulin-4R/R mice showed a dramatically reduced lifespan compared to Ltbp4S−/− or Fibulin-4R/R mice, which survive to adulthood. This dramatic reduction in survival of Ltbp4S−/−;Fibulin-4R/R mice correlates with severely impaired elastogenesis resulting in defective alveolar septation and distal airspace enlargement in lung, and increased aortic wall thickness with severely fragmented elastic lamellae. Additionally, Ltbp4S−/−;Fibulin-4R/R mice suffer from aortic aneurysm formation combined with aortic tortuosity, in contrast to Ltbp4S−/− or Fibulin-4R/R mice. Together, in accordance with our previous biochemical findings of a physical interaction between Ltbp-4L and fibulin-4, these novel in vivo data clearly establish a functional link between Ltbp-4L and fibulin-4 as a crucial molecular requirement for survival and

  7. Comparison of Cox Model and K-Nearest Neighbor to Estimation of Survival in Kidney Transplant Patients

    Directory of Open Access Journals (Sweden)

    J. Faradmal

    2016-01-01

    Full Text Available Introduction & Objective: Cox model is a common method to estimate survival and validity of the results is dependent on the proportional hazards assumption. K- Nearest neighbor is a nonparametric method for survival probability in heterogeneous communities. The purpose of this study was to compare the performance of k- nearest neighbor method (K-NN with Cox model. Materials & Methods: This retrospective cohort study was conducted in Hamadan Province, on 475 patients who had undergone kidney transplantation from 1994 to 2011. Data were extracted from patients’ medical records using a checklist. The duration of the time between kidney transplantation and rejection was considered as the surviv­al time. Cox model and k- nearest neighbor method were used for Data modeling. The prediction error Brier score was used to compare the performance models. Results: Out of 475 transplantations, 55 episodes of rejection occurred. 5, 10 and 15 year survival rates of transplantation were 91.70 %, 84.90% and 74.50%, respectively. The number of neighborhood optimized using cross validation method was 45. Cumulative Brier score of k-NN algorithm for t=5, 10 and 15 years were 0.003, 0.006 and 0.007, respectively. Cumulative Brier of score Cox model for t=5, 10 and 15 years were 0.036, 0.058 and 0.058, respectively. Prediction error of k-NN algorithm for t=5, 10 and 15 years was less than Cox model that shows that the k-NN method outperforms. Conclusions: The results of this study show that the predictions of KNN has higher accuracy than the Cox model when sample sizes and the number of predictor variables are high. Sci J Hamadan Univ Med Sci . 2016; 22 (4 :300-308

  8. Model-based estimates of annual survival rate are preferable to observed maximum lifespan statistics for use in comparative life-history studies

    Science.gov (United States)

    Krementz, D.G.; Sauer, J.R.; Nichols, J.D.

    1989-01-01

    Estimates of longevity are available for many animals, and are commonly used in comparative life-history analyses. We suggest that annual survival rate is more appropriate life history parameter for most comparative life history analyses. Observed maximum longevities were not correlated with the annual survival rate estimates and appear to be unstable over time. We recommend that observed maximum lifespans not be used in life history analyses.

  9. Estimation of the Magnetotelluric Response Function: The Path from Robust Estimation to a Stable Maximum Likelihood Estimator

    Science.gov (United States)

    Chave, Alan D.

    2017-08-01

    The robust statistical model of a Gaussian core contaminated by outlying data in use since the 1980s, and which underlies modern estimation of the magnetotelluric (MT) response function, is re-examined from first principles. The residuals from robust estimators applied to MT data are shown to be systematically long-tailed compared to a distribution based on the Gaussian and hence inconsistent with the robust model. Instead, MT data are pervasively described by the stable distribution family for which the Gaussian is an end member, but whose remaining distributions have algebraic rather than exponential tails. The validity of the stable model is rigorously demonstrated using a permutation test. A maximum likelihood estimator (MLE), including the use of a remote reference, that exploits the stable nature of MT data is formulated, and its two-stage implementation, in which stable parameters are first fit to the residuals, and then the MT responses are solved for, with iteration between them, is described. The MLE is inherently robust, but differs from a conventional robust estimator because it is based on a statistical model derived from the data rather than being ad hoc. Finally, the covariance matrices obtained from MT data are pervasively improper as a result of weak non-stationarity, and the Cramér-Rao lower bound for the improper covariance matrix is derived, resulting in reliable second-order statistics for MT responses. The stable MLE was applied to an exemplar broadband data set from northwest Namibia. The stable MLE is shown to be consistent with the statistical model underlying linear regression and hence is unconditionally unbiased, in contrast to the robust model. The MLE is compared to conventional robust remote reference and two-stage estimators, establishing that the standard errors of the former are systematically smaller than for either of the latter, and that the standardized differences between them exhibit excursions that are both too frequent and

  10. An ensemble survival model for estimating relative residual longevity following stroke: Application to mortality data in the chronic dialysis population.

    Science.gov (United States)

    Phadnis, Milind A; Wetmore, James B; Shireman, Theresa I; Ellerbeck, Edward F; Mahnken, Jonathan D

    2017-12-01

    Time-dependent covariates can be modeled within the Cox regression framework and can allow both proportional and nonproportional hazards for the risk factor of research interest. However, in many areas of health services research, interest centers on being able to estimate residual longevity after the occurrence of a particular event such as stroke. The survival trajectory of patients experiencing a stroke can be potentially influenced by stroke type (hemorrhagic or ischemic), time of the stroke (relative to time zero), time since the stroke occurred, or a combination of these factors. In such situations, researchers are more interested in estimating lifetime lost due to stroke rather than merely estimating the relative hazard due to stroke. To achieve this, we propose an ensemble approach using the generalized gamma distribution by means of a semi-Markov type model with an additive hazards extension. Our modeling framework allows stroke as a time-dependent covariate to affect all three parameters (location, scale, and shape) of the generalized gamma distribution. Using the concept of relative times, we answer the research question by estimating residual life lost due to ischemic and hemorrhagic stroke in the chronic dialysis population.

  11. The effect of time to defibrillation and targeted temperature management on functional survival after out-of-hospital cardiac arrest.

    Science.gov (United States)

    Drennan, Ian R; Lin, Steve; Thorpe, Kevin E; Morrison, Laurie J

    2014-11-01

    Cardiac arrest physiology has been proposed to occur in three distinct phases: electrical, circulatory and metabolic. There is limited research evaluating the relationship of the 3-phase model of cardiac arrest to functional survival at hospital discharge. Furthermore, the effect of post-cardiac arrest targeted temperature management (TTM) on functional survival during each phase is unknown. To determine the effect of TTM on the relationship between the time of initial defibrillation during each phase of cardiac arrest and functional survival at hospital discharge. This was a retrospective observational study of consecutive adult (≥18 years) out-of-hospital cardiac arrest (OHCA) patients with initial shockable rhythms. Included patients obtained a return of spontaneous circulation (ROSC) and were eligible for TTM. Multivariable logistic regression was used to determine predictors of functional survival at hospital discharge. There were 20,165 OHCA treated by EMS and 871 patients were eligible for TTM. Of these patients, 622 (71.4%) survived to hospital discharge and 487 (55.9%) had good functional survival. Good functional survival was associated with younger age (OR 0.94; 95% CI 0.93-0.95), shorter times from collapse to initial defibrillation (OR 0.73; 95% CI 0.65-0.82), and use of post-cardiac arrest TTM (OR 1.49; 95% CI 1.07-2.30). Functional survival decreased during each phase of the model (65.3% vs. 61.7% vs. 50.2%, Pdefibrillation and was decreased during each successive phase of the 3-phase model. Post-cardiac arrest TTM was associated with improved functional survival. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  12. Expanding functional repertoires of fungal peroxisomes: contribution to growth and survival processes

    Directory of Open Access Journals (Sweden)

    Jun-ichi eMARUYAMA

    2013-07-01

    Full Text Available It has long been regarded that the primary function of fungal peroxisomes is limited to the β-oxidation of fatty acids, as mutants lacking peroxisomal function fail to grow in minimal medium containing fatty acids as the sole carbon source. However, studies in filamentous fungi have revealed that peroxisomes have diverse functional repertoires. This review describes the essential roles of peroxisomes in the growth and survival processes of filamentous fungi. One such survival mechanism involves the Woronin body, a Pezizomycotina-specific organelle that plugs the septal pore upon hyphal lysis to prevent excessive cytoplasmic loss. A number of reports have demonstrated that Woronin bodies are derived from peroxisomes. Specifically, the Woronin body protein Hex1 is targeted to peroxisomes by peroxisomal targeting sequence 1 (PTS1 and forms a self-assembled structure that buds from peroxisomes to form the Woronin body. Peroxisomal deficiency reduces the ability of filamentous fungi to prevent excessive cytoplasmic loss upon hyphal lysis, indicating that peroxisomes contribute to the survival of these multicellular organisms. Peroxisomes were also recently found to play a vital role in the biosynthesis of biotin, which is an essential cofactor for various carboxylation and decarboxylation reactions. In biotin-prototrophic fungi, peroxisome-deficient mutants exhibit growth defects when grown on glucose as a carbon source due to biotin auxotrophy. The biotin biosynthetic enzyme BioF (7-keto-8-aminopelargonic acid synthase contains a PTS1 motif that is required for both peroxisomal targeting and biotin biosynthesis. In plants, the BioF protein contains a conserved PTS1 motif and is also localized in peroxisomes. These findings indicate that the involvement of peroxisomes in biotin biosynthesis is evolutionarily conserved between fungi and plants, and that peroxisomes play a key role in fungal growth.

  13. Osteocalcin protects pancreatic beta cell function and survival under high glucose conditions.

    Science.gov (United States)

    Kover, Karen; Yan, Yun; Tong, Pei Ying; Watkins, Dara; Li, Xiaoyu; Tasch, James; Hager, Melissa; Clements, Mark; Moore, Wayne V

    2015-06-19

    Diabetes is characterized by progressive beta cell dysfunction and loss due in part to oxidative stress that occurs from gluco/lipotoxicity. Treatments that directly protect beta cell function and survival in the diabetic milieu are of particular interest. A growing body of evidence suggests that osteocalcin, an abundant non-collagenous protein of bone, supports beta cell function and proliferation. Based on previous gene expression data by microarray, we hypothesized that osteocalcin protects beta cells from glucose-induced oxidative stress. To test our hypothesis we cultured isolated rat islets and INS-1E cells in the presence of normal, high, or high glucose ± osteocalcin for up to 72 h. Oxidative stress and viability/mitochondrial function were measured by H2O2 assay and Alamar Blue assay, respectively. Caspase 3/7 activity was also measured as a marker of apoptosis. A functional test, glucose stimulated insulin release, was conducted and expression of genes/protein was measured by qRT-PCR/western blot/ELISA. Osteocalcin treatment significantly reduced high glucose-induced H2O2 levels while maintaining viability/mitochondrial function. Osteocalcin also significantly improved glucose stimulated insulin secretion and insulin content in rat islets after 48 h of high glucose exposure compared to untreated islets. As expected sustained high glucose down-regulated gene/protein expression of INS1 and BCL2 while increasing TXNIP expression. Interestingly, osteocalcin treatment reversed the effects of high glucose on gene/protein expression. We conclude that osteocalcin can protect beta cells from the negative effects of glucose-induced oxidative stress, in part, by reducing TXNIP expression, thereby preserving beta cell function and survival. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Odds and Probabilities Estimation for the Survival of Breast Cancer Patients with Cancer Stages 2 & 3

    Directory of Open Access Journals (Sweden)

    Urrutia Jackie D.

    2016-01-01

    Full Text Available Breast cancer is one of the leading causes of death in the Philippines. One out of four who are diagnosed with breast cancer die within the first five years, and no less than 40 percent die within 10 years and it has continous rise as time passes by. Therefore, it is very important to know the factors that can help for the survival rate of the patients. The purpose of this study is to identify the best possible treatment or combination of treatments. The researchers considered four independent variables namely: Completed Surgery, Completed Chemotherapy, Completed Hormonotherapy and Completed Radiotherapy. The researchers limit this study for only 160 patients with stage 2 and 135 with stage 3 for a total of 295 patients considering the data gathered from three hospitals from Metro Manila. The names of the hospitals were not declared due to confidentiality of data. In identifying the best treatment or combination of treatments, odds, probabilities and odds ratios of patients, Logistic Regression Analysis was used.

  15. DOCK8 deficiency impairs CD8 T cell survival and function in humans and mice

    Science.gov (United States)

    Randall, Katrina L.; Chan, Stephanie S.-Y.; Ma, Cindy S.; Fung, Ivan; Mei, Yan; Yabas, Mehmet; Tan, Andy; Arkwright, Peter D.; Al Suwairi, Wafaa; Lugo Reyes, Saul Oswaldo; Yamazaki-Nakashimada, Marco A.; de la Luz Garcia-Cruz, Maria; Smart, Joanne M.; Picard, Capucine; Okada, Satoshi; Jouanguy, Emmanuelle; Casanova, Jean-Laurent; Lambe, Teresa; Cornall, Richard J.; Russell, Sarah; Oliaro, Jane; Tangye, Stuart G.; Bertram, Edward M.

    2011-01-01

    In humans, DOCK8 immunodeficiency syndrome is characterized by severe cutaneous viral infections. Thus, CD8 T cell function may be compromised in the absence of DOCK8. In this study, by analyzing mutant mice and humans, we demonstrate a critical, intrinsic role for DOCK8 in peripheral CD8 T cell survival and function. DOCK8 mutation selectively diminished the abundance of circulating naive CD8 T cells in both species, and in DOCK8-deficient humans, most CD8 T cells displayed an exhausted CD45RA+CCR7− phenotype. Analyses in mice revealed the CD8 T cell abnormalities to be cell autonomous and primarily postthymic. DOCK8 mutant naive CD8 T cells had a shorter lifespan and, upon encounter with antigen on dendritic cells, exhibited poor LFA-1 synaptic polarization and a delay in the first cell division. Although DOCK8 mutant T cells underwent near-normal primary clonal expansion after primary infection with recombinant influenza virus in vivo, they showed greatly reduced memory cell persistence and recall. These findings highlight a key role for DOCK8 in the survival and function of human and mouse CD8 T cells. PMID:22006977

  16. Surviving endoplasmic reticulum stress is coupled to altered chondrocyte differentiation and function.

    Directory of Open Access Journals (Sweden)

    Kwok Yeung Tsang

    2007-03-01

    Full Text Available In protein folding and secretion disorders, activation of endoplasmic reticulum (ER stress signaling (ERSS protects cells, alleviating stress that would otherwise trigger apoptosis. Whether the stress-surviving cells resume normal function is not known. We studied the in vivo impact of ER stress in terminally differentiating hypertrophic chondrocytes (HCs during endochondral bone formation. In transgenic mice expressing mutant collagen X as a consequence of a 13-base pair deletion in Col10a1 (13del, misfolded alpha1(X chains accumulate in HCs and elicit ERSS. Histological and gene expression analyses showed that these chondrocytes survived ER stress, but terminal differentiation is interrupted, and endochondral bone formation is delayed, producing a chondrodysplasia phenotype. This altered differentiation involves cell-cycle re-entry, the re-expression of genes characteristic of a prehypertrophic-like state, and is cell-autonomous. Concomitantly, expression of Col10a1 and 13del mRNAs are reduced, and ER stress is alleviated. ERSS, abnormal chondrocyte differentiation, and altered growth plate architecture also occur in mice expressing mutant collagen II and aggrecan. Alteration of the differentiation program in chondrocytes expressing unfolded or misfolded proteins may be part of an adaptive response that facilitates survival and recovery from the ensuing ER stress. However, the altered differentiation disrupts the highly coordinated events of endochondral ossification culminating in chondrodysplasia.

  17. Genome-wide association of functional traits linked with Campylobacter jejuni survival from farm to fork.

    Science.gov (United States)

    Yahara, Koji; Méric, Guillaume; Taylor, Aidan J; de Vries, Stefan P W; Murray, Susan; Pascoe, Ben; Mageiros, Leonardos; Torralbo, Alicia; Vidal, Ana; Ridley, Anne; Komukai, Sho; Wimalarathna, Helen; Cody, Alison J; Colles, Frances M; McCarthy, Noel; Harris, David; Bray, James E; Jolley, Keith A; Maiden, Martin C J; Bentley, Stephen D; Parkhill, Julian; Bayliss, Christopher D; Grant, Andrew; Maskell, Duncan; Didelot, Xavier; Kelly, David J; Sheppard, Samuel K

    2017-01-01

    Campylobacter jejuni is a major cause of bacterial gastroenteritis worldwide, primarily associated with the consumption of contaminated poultry. C. jejuni lineages vary in host range and prevalence in human infection, suggesting differences in survival throughout the poultry processing chain. From 7343 MLST-characterised isolates, we sequenced 600 C. jejuni and C. coli isolates from various stages of poultry processing and clinical cases. A genome-wide association study (GWAS) in C. jejuni ST-21 and ST-45 complexes identified genetic elements over-represented in clinical isolates that increased in frequency throughout the poultry processing chain. Disease-associated SNPs were distinct in these complexes, sometimes organised in haplotype blocks. The function of genes containing associated elements was investigated, demonstrating roles for cj1377c in formate metabolism, nuoK in aerobic survival and oxidative respiration, and cj1368-70 in nucleotide salvage. This work demonstrates the utility of GWAS for investigating transmission in natural zoonotic pathogen populations and provides evidence that major C. jejuni lineages have distinct genotypes associated with survival, within the host specific niche, from farm to fork. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Genetic parameter estimates for functional herd life for the South ...

    African Journals Online (AJOL)

    Longevity reflects the ability of a cow to avoid being culled for low production, low fertility or illness. Longevity can be used in breeding programmes if genetic parameters are known. Various measures are used for longevity. In this study survival in each of the first three lactations was analysed. Survival was denoted by a 1 if ...

  19. Estimating functional brain networks by incorporating a modularity prior.

    Science.gov (United States)

    Qiao, Lishan; Zhang, Han; Kim, Minjeong; Teng, Shenghua; Zhang, Limei; Shen, Dinggang

    2016-11-01

    Functional brain network analysis has become one principled way of revealing informative organization architectures in healthy brains, and providing sensitive biomarkers for diagnosis of neurological disorders. Prior to any post hoc analysis, however, a natural issue is how to construct "ideal" brain networks given, for example, a set of functional magnetic resonance imaging (fMRI) time series associated with different brain regions. Although many methods have been developed, it is currently still an open field to estimate biologically meaningful and statistically robust brain networks due to our limited understanding of the human brain as well as complex noises in the observed data. Motivated by the fact that the brain is organized with modular structures, in this paper, we propose a novel functional brain network modeling scheme by encoding a modularity prior under a matrix-regularized network learning framework, and further formulate it as a sparse low-rank graph learning problem, which can be solved by an efficient optimization algorithm. Then, we apply the learned brain networks to identify patients with mild cognitive impairment (MCI) from normal controls. We achieved 89.01% classification accuracy even with a simple feature selection and classification pipeline, which significantly outperforms the conventional brain network construction methods. Moreover, we further explore brain network features that contributed to MCI identification, and discovered potential biomarkers for personalized diagnosis. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Prior exercise improves survival, infarct healing, and left ventricular function after myocardial infarction.

    Science.gov (United States)

    de Waard, Monique C; Duncker, Dirk J

    2009-09-01

    We investigated the effects of voluntary wheel running before an acute myocardial infarction (MI) on survival, left ventricular (LV) remodeling and dysfunction and whether exercise before and after MI provides superior protection compared with either exercise intervention alone. After 2 wk of voluntary wheel running or sedentary housing, MI was induced in C57Bl/6 mice, after which exercise was stopped (EX-MI-SED and SED-MI-SED groups, where EX is exercise and SED is sedentary) or continued (EX-MI-EX and SED-MI-EX groups) for a period of 8 wk. Exercise after MI in SED-MI-EX mice had no effect on survival, the area of infarction, and global LV remodeling, but attenuated fibrosis and apoptosis in the remote myocardium and blunted LV dysfunction and pulmonary congestion compared with SED-MI-SED mice. Exercise before MI in both EX-MI-SED and EX-MI-EX mice decreased post-MI mortality compared with both SED-MI-SED and SED-MI-EX mice. Furthermore, in both pre-MI exercise groups, the infarct area was thicker, whereas interstitial fibrosis and apoptosis in the remote LV myocardium were blunted. In contrast, the ameliorating effects of either pre-MI or post-MI exercise alone on LV dysfunction were lost in EX-MI-EX mice, which may in part be related to the increased daily exercise distance in the first week post-MI in EX-MI-EX versus SED-MI-EX mice. In conclusion, exercise before or after MI blunted LV dysfunction, whereas only exercise before MI improved survival. These findings suggest that even when regular physical activity fails to prevent an acute MI, it can still act to improve cardiac function and survival after MI.

  1. Towards an Early Software Effort Estimation Based on Functional and Non-Functional Requirements

    NARCIS (Netherlands)

    Kassab, M.; Daneva, Maia; Ormanjieva, Olga; Abran, A.; Braungarten, R.; Dumke, R.; Cuadrado-Gallego, J.; Brunekreef, J.

    2009-01-01

    The increased awareness of the non-functional requirements as a key to software project and product success makes explicit the need to include them in any software project effort estimation activity. However, the existing approaches to defining size-based effort relationships still pay insufficient

  2. Pedotransfer functions estimating soil hydraulic properties using different soil parameters

    DEFF Research Database (Denmark)

    Børgesen, Christen Duus; Iversen, Bo Vangsø; Jacobsen, Ole Hørbye

    2008-01-01

    Estimates of soil hydraulic properties using pedotransfer functions (PTF) are useful in many studies such as hydrochemical modelling and soil mapping. The objective of this study was to calibrate and test parametric PTFs that predict soil water retention and unsaturated hydraulic conductivity...... conductivity parameters. A larger data set (1618 horizons) with a broader textural range was used in the development of PTFs to predict the van Genuchten parameters. The PTFs using either three or seven textural classes combined with soil organic mater and bulk density gave the most reliable predictions...... of the hydraulic properties of the studied soils. We found that introducing measured water content as a predictor generally gave lower errors for water retention predictions and higher errors for conductivity predictions. The best of the developed PTFs for predicting hydraulic conductivity was tested against PTFs...

  3. Estimating a distribution function of the tumor size at metastasis.

    Science.gov (United States)

    Xu, J L; Prorok, P C

    1998-09-01

    In studying the relationship between the size of primary cancers and the occurrence of metastases, two quantities are of prime importance. The first is the distribution of tumor size at the point of metastatic transition, while the second is the probability that detectable metastases are present when cancer comes to medical attention. Kimmel and Flehinger (1991, Biometrics 47, 987-1004) developed a general nonparametric model and studied its two limiting cases. Because of unidentifiablity of their general model, a new identifiable model is introduced by making the hazard function for detecting a metastatic cancer a constant. The new model includes Kimmel and Flehinger's (1991) second limiting model as a special case. An estimator of the tumor size distribution at metastases is proposed. The result is applied to a set of colorectal cancer data.

  4. Functional Gain After Inpatient Stroke Rehabilitation: Correlates and Impact on Long-Term Survival.

    Science.gov (United States)

    Scrutinio, Domenico; Monitillo, Vincenzo; Guida, Pietro; Nardulli, Roberto; Multari, Vincenzo; Monitillo, Francesco; Calabrese, Gianluigi; Fiore, Pietro

    2015-10-01

    Prediction of functional outcome after stroke rehabilitation (SR) is a growing field of interest. The association between SR and survival still remains elusive. We sought to investigate the factors associated with functional outcome after SR and whether the magnitude of functional improvement achieved with rehabilitation is associated with long-term mortality risk. The study population consisted of 722 patients admitted for SR within 90 days of stroke onset, with an admission functional independence measure (FIM) score of stroke onset to rehabilitation admission (PStroke Scale score at rehabilitation admission (P<0.001), and aphasia (P=0.021) were independently associated with FIM gain. The R2 of the model was 0.275. During a median follow-up of 6.17 years, 36.9% of the patients died. At multivariable Cox analysis, age (P<0.0001), coronary heart disease (P=0.018), atrial fibrillation (P=0.042), total cholesterol (P=0.015), and total FIM gain (P<0.0001) were independently associated with mortality. The adjusted hazard ratio for death significantly decreased across tertiles of increasing FIM gain. Several factors are independently associated with functional gain after SR. Our findings strongly suggest that the magnitude of functional improvement is a powerful predictor of long-term mortality in patients admitted for SR. © 2015 American Heart Association, Inc.

  5. Relationship between estimated body fat and some respiratory function indices.

    Science.gov (United States)

    Sanya, A O; Adesina, A T

    1998-10-01

    To find the relationship between estimated body fat and respiratory function indices. Cross sectional study of volunteers in the physiotherapy department. Physiotherapy patients with no respiratory or neuromascular diseases. Quetelet index (as measure of body fat), vital capacity and breath holding time. Their ages ranged from 20 year to 60 years with a mean 24.20 +/- 6.59 years and 29.72 +/- 14.18 years in males and females respectively. Subjects whose quetelet index was about 30 kg/m2 and above were classified as obese. None of the male subjects fell into the obese category, while six of the 50 female subjects fell into the obese category. Significant differences were observed in the mean of the Quetelet index, percent predicted vital capacity and the breath holding time between the normal female and the obese female subjects. A high but inverse relationship was found between estimated body fat and each percent predicted vital capacity and breath holding time in subjects whose Quetelet index was above 30 kg/m2. There was also a high and positive correlation between percent predicted vital capacity and breath holding time in subjects with Quetelet index above 30 kg/m2. These findings were attributed to the restrictive effect of excess adipose tissue located around the thorax and the abdomen. It was concluded that adequate caution should be taken during exercise therapy for patients with a Quetelet index value above 30 kg/m2 to enable them exercise safely and with respiratory efficiency.

  6. Pyruvate oral rehydration solution improved visceral function and survival in shock rats.

    Science.gov (United States)

    Yu, Wen; Hu, Sen; Xie, Zhi-Yi; He, Zhi-Jie; Luo, Hong-Min; Lin, Hong-Yuan; Zhou, Fang-Qiang; Sheng, Zhi-Yong

    2015-01-01

    Recent findings showed advantages of a novel pyruvate-enriched oral rehydration solution (Pyr-ORS) in resuscitation of burns. This study focused on effects of Pyr-ORS on the visceral blood perfusion (VBP), gastrointestinal function, and survival rate, compared with the bicarbonate-based World Health Organization-guided oral rehydration solution (WHO-ORS), during intragastric rehydration of lethal hemorrhagic shock in rats. Sixty adult rats were subjected to 45% total blood volume loss and were randomly allocated to the following three groups (n = 20): group NR (no fluid resuscitation), group PORS (oral Pyr-ORS rehydration), and group BORS (oral WHO-ORS rehydration), respectively. Other 10 rats were served as group NH (the sham group). Enteral rehydration lasted for 4 h after hemorrhage. The mean arterial pressure (MAP), VBP, and plasma enzymes activities of heart, liver, and kidney, and intestinal fatty acid binding protein were measured. Liver, kidney, and ileum were harvested for the evaluation of activities of oxidative enzymes and intestinal barrier protein (ZO-1). Other 84 rats with identical procedures without sampling were observed for their 24-h survival rates. Pyr-ORS was more effective in enhancing the MAP and VBP, inhibiting tissue oxidative damage, and improving organ function, compared with WHO-ORS. Hypoxic lactic acidosis was fully corrected in group PORS in 4 h, whereas it worsened in group BORS, and the 24-h survival rate was twice higher in group PORS than in group BORS (45.8 versus 20.8%, P rehydration of lethal hemorrhagic shock. The Pyr-ORS may be an ideal oral fluid in resuscitation of hypovolemic shock, especially in prehospital and resource-poor settings. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Anti-inflammatory thalidomide improves islet grafts survival and functions in a xenogenic environment.

    Directory of Open Access Journals (Sweden)

    Chunguang Chen

    Full Text Available Thalidomide possesses both anti-inflammatory and anti-angiogenic properties. This study investigates its potential application in islet transplantation with a xenogenic transplantation model. Transplantation was performed using C57Bl/6 mice and NMRI nu/nu mice as recipients of porcine islets. Moreover, islet graft vasculature and inflammation were investigated to identify the mechanisms of thalidomide action. In the immunocompetent environment of C57Bl/6 mice, a fast graft rejection was observed. The group treated with thalidomide 200 mg/kg BW per day achieved and maintained euglycemia in the complete observation period for 42 days. The treated mice had more functional islet graft mass with less leukocyte infiltration. The pro-inflammatory TNF-alpha and VEGF content in islet grafted kidneys was significantly lowered by the treatment. By comparison, thalidomide was not effective in improving graft survival in immunocompromised nude mice. It strongly inhibited the VEGF and TNF-alpha-induced endothelial proliferation of isolated pig islets in a dose dependent manner. The magnitude of thalidomide's inhibitory effect was nearly identical to the effect of VEGF- receptor 2 inhibitor SU416 and anti-TNF-receptor 1 neutralizing antibody, and was reversed by sphingosine-1-phosphate. In conclusion, the anti-inflammatory effect of thalidomide improved islet graft survival and function in a transplantation model with a maximum immune barrier.

  8. Patulin induces pro-survival functions via autophagy inhibition and p62 accumulation

    Science.gov (United States)

    Guo, X; Dong, Y; Yin, S; Zhao, C; Huo, Y; Fan, L; Hu, H

    2013-01-01

    Patulin (PAT) is one of the most common mycotoxins found in moldy fruits. Skin contact is one of the most likely exposure routes of PAT. Investigation of dermal toxicity of PAT is clearly needed and has been highlighted by WHO. In the present study, using human keratinocyte HaCaT cells as a model, we found that treatment with PAT caused an increased autophagosome accumulation. Measurements of autophagic flux demonstrated that the accumulation of autophagosomes by PAT was not directly due to enhanced autophagosome formation but due to inhibition of autophagosome degradation. Reductions in the activities of the lysosomal enzymes cathepsin B and cathepsin D by PAT might contribute to this inhibitory effect. Consistent with this, inhibition of autophagosome degradation by PAT resulted in accumulation of p62 that functioned as a pro-survival signal. The pro-survival function of p62 was found to be attributed to reactive oxygen species-mediated cytoprotective endoplasmic reticulum (ER) stress response. ER stress exerted cytoprotective effect via extracellular signal-regulated kinase1/2-dependent B-cell CLL/lymphoma 2-associated agonist of cell death inhibitory phosphorylation. Given the critical role of autophagy and its substrate p62 in carcinogenesis, our findings may have important implications in PAT-induced skin carcinogenesis. PMID:24091665

  9. IL-7 promotes T cell viability, trafficking, and functionality and improves survival in sepsis.

    Science.gov (United States)

    Unsinger, Jacqueline; McGlynn, Margaret; Kasten, Kevin R; Hoekzema, Andrew S; Watanabe, Eizo; Muenzer, Jared T; McDonough, Jacquelyn S; Tschoep, Johannes; Ferguson, Thomas A; McDunn, Jonathan E; Morre, Michel; Hildeman, David A; Caldwell, Charles C; Hotchkiss, Richard S

    2010-04-01

    Sepsis is a highly lethal disorder characterized by widespread apoptosis-induced depletion of immune cells and the development of a profound immunosuppressive state. IL-7 is a potent antiapoptotic cytokine that enhances immune effector cell function and is essential for lymphocyte survival. In this study, recombinant human IL-7 (rhIL-7) efficacy and potential mechanisms of action were tested in a murine peritonitis model. Studies at two independent laboratories showed that rhIL-7 markedly improved host survival, blocked apoptosis of CD4 and CD8 T cells, restored IFN-gamma production, and improved immune effector cell recruitment to the infected site. Importantly, rhIL-7 also prevented a hallmark of sepsis (i.e., the loss of delayed-type hypersensitivity), which is an IFN-gamma- and T cell-dependent response. Mechanistically, rhIL-7 significantly increased the expression of the leukocyte adhesion markers LFA-1 and VLA-4, consistent with its ability to improve leukocyte function and trafficking to the infectious focus. rhIL-7 also increased the expression of CD8. The potent antiapoptotic effect of rhIL-7 was due to increased Bcl-2, as well as to a dramatic decrease in sepsis-induced PUMA, a heretofore unreported effect of IL-7. If additional animal studies support its efficacy in sepsis and if current clinical trials continue to confirm its safety in diverse settings, rhIL-7 should be strongly considered for clinical trials in sepsis.

  10. Tug of War between Survival and Death: Exploring ATM Function in Cancer

    Directory of Open Access Journals (Sweden)

    Venturina Stagni

    2014-03-01

    Full Text Available Ataxia-telangiectasia mutated (ATM kinase is a one of the main guardian of genome stability and plays a central role in the DNA damage response (DDR. The deregulation of these pathways is strongly linked to cancer initiation and progression as well as to the development of therapeutic approaches. These observations, along with reports that identify ATM loss of function as an event that may promote tumor initiation and progression, point to ATM as a bona fide tumor suppressor. The identification of ATM as a positive modulator of several signalling networks that sustain tumorigenesis, including oxidative stress, hypoxia, receptor tyrosine kinase and AKT serine-threonine kinase activation, raise the question of whether ATM function in cancer may be more complex. This review aims to give a complete overview on the work of several labs that links ATM to the control of the balance between cell survival, proliferation and death in cancer.

  11. Application of risk-rated profit model functions in estimation of economic values for indigenous chicken breeding.

    Science.gov (United States)

    Okeno, Tobias O; Magothe, Thomas M; Kahi, Alexander K; Peters, Kurt J

    2012-08-01

    The economic values for productive (egg number, average daily gain, live weight, and mature weight) and functional (fertility, hatchability, broodiness, survival rate, feed intake, and egg weight) traits were derived for three production systems utilizing indigenous chicken in Kenya. The production systems considered were free-range, semi-intensive, and intensive system and were evaluated based on fixed flock size and fixed feed resource production circumstances. A bio-economic model that combined potential performances, feeding strategies, optimum culling strategies, farmer's preferences and accounted for imperfect knowledge concerning risk attitude of farmers and economic dynamics was employed to derive risk-rated economic values. The economic values for all the traits were highest in free-range system under the two production circumstances and decreased with level of intensification. The economic values for egg number, average daily gain, live weight, fertility, hatchability, and survival rate were positive while those for mature weight, broodiness, egg weight, and feed intake were negative. Generally, the economic values estimated under fixed feed resource production circumstances were higher than those derived under fixed flock size. The difference between economic values estimated using simple (traditional) and risk-rated profit model functions ranged from -47.26% to +67.11% indicating that inclusion of risks in estimation of economic values is important. The results of this study suggest that improvement targeting egg number, average daily gain, live weight, fertility, hatchability, and survival rate would have a positive impact on profitability of indigenous chicken production in Kenya.

  12. Decay ratio estimation using the instantaneous autocorrelation function

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Fernandez, Jose E.; Prieto-Guerrero, Alfonso [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, Mexico, D.F. 09340 (Mexico); Espinosa-Paredes, Gilberto, E-mail: gepe@xanum.uam.m [Division de Ciencias Basicas e Ingenieria, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, Mexico, D.F. 09340 (Mexico)

    2010-10-15

    Research highlights: {yields} The ACEDR measure reflects major long-term changes in BWR stability. {yields} Synthetic and real neutronic signals were used to validate the method. {yields} The method was tested on the Laguna Verde Unit 1. {yields} The method was tested in three events reported in the Ringhals stability benchmark. {yields} The ACEDR measure exhibits a series of interesting properties. {yields} The ACEDR can detect long signal trends. - Abstract: In this paper a novel method based on the instantaneous autocorrelation function (IACF) is proposed to determine the time evolution of the linear stability parameters of a boiling water reactor (BWR) using neutronic noise signals. The IACF allow us to track the instantaneous signal envelope changes in time by defining an envelope instantaneous decay ratio (EIDR) which is used as a measure of local stability. In order to account for long-term changes in BWR stability, the accumulated envelope-based decay ratio (ACEDR) measure is introduced as the product of the local EIDRs. As it is shown in this paper, the ACEDR measure clearly reflects major long-term changes in BWR stability. Last the natural resonant frequency of the nuclear reactor is estimated from the Fourier transform of a weighted version of the IACF called generalized local autocorrelation function (GLACF). In order to validate our method, synthetic and real neutronic signals were used. The methodology was tested on the Laguna Verde Unit 1 and three events reported in the Ringhals stability benchmark.

  13. Can a Bayesian Belief Network Be Used to Estimate 1-year Survival in Patients With Bone Sarcomas?

    Science.gov (United States)

    Nandra, Rajpal; Parry, Michael; Forsberg, Jonathan; Grimer, Robert

    2017-06-01

    Extremity sarcoma has a preponderance to present late with advanced stage at diagnosis. It is important to know why these patients die early from sarcoma and to predict those at high risk. Currently we have mid- to long-term outcome data on which to counsel patients and support treatment decisions, but in contrast to other cancer groups, very little on short-term mortality. Bayesian belief network modeling has been used to develop decision-support tools in various oncologic diagnoses, but to our knowledge, this approach has not been applied to patients with extremity sarcoma. We sought to (1) determine whether a Bayesian belief network could be used to estimate the likelihood of 1-year mortality using receiver operator characteristic analysis; (2) describe the hierarchal relationships between prognostic and outcome variables; and (3) determine whether the model was suitable for clinical use using decision curve analysis. We considered all patients treated for primary bone sarcoma between 1970 and 2012, and excluded secondary metastasis, presentation with local recurrence, and benign tumors. The institution's database yielded 3499 patients, of which six (0.2%) were excluded. Data extracted for analysis focused on patient demographics (age, sex), tumor characteristics at diagnosis (size, metastasis, pathologic fracture), survival, and cause of death. A Bayesian belief network generated conditional probabilities of variables and survival outcome at 1 year. A lift analysis determined the hierarchal relationship of variables. Internal validation of 699 test patients (20% dataset) determined model accuracy. Decision curve analysis was performed comparing net benefit (capped at 85.5%) for all threshold probabilities (survival output from model). We successfully generated a Bayesian belief network with five first-degree associates and describe their conditional relationship with survival after the diagnosis of primary bone sarcoma. On internal validation, the resultant

  14. Sexual functioning in military personnel: preliminary estimates and predictors.

    Science.gov (United States)

    Wilcox, Sherrie L; Redmond, Sarah; Hassan, Anthony M

    2014-10-01

    Although the military is a young and vigorous force, service members and veterans may experience sexual functioning problems (SFPs) as a result of military service. Sexual functioning can be impaired by physical, psychological, and social factors and can impact quality of life (QOL) and happiness. This study aims to estimate rates and correlates of SFPs in male military personnel across demographic and psychosocial characteristics, to examine the QOL concomitants, and to evaluate barriers for treatment seeking. This exploratory cross-sectional study was conducted using data from a larger nationwide study conducted between October 2013 and November 2013. This sample consists of 367 male active duty service members and recent veterans (military personnel) age 40 or younger. Erectile dysfunction (ED) was determined using the five-item International Index of Erectile Function, sexual dysfunction (SD) was determined using the Arizona Sexual Experiences Scale, Male, and QOL was determined using the World Health Organization Quality of Life, Brief. SFPs were associated with various demographic, physical, and psychosocial risk factors. The rates of SD and ED were 8.45% and 33.24%, respectively, for male military personnel aged 21-40. Those who were 36-40, nonmarried, nonwhite, and of lower educational attainment reported the highest rates of SFPs. Male military personnel with poor physical and psychosocial health presented the greatest risk for ED and SD. SFPs were associated with reduced QOL and lower happiness, and barriers for treatment were generally related to social barriers. SFPs in young male military personnel are an important public health concern that can severely impact QOL and happiness. © 2014 International Society for Sexual Medicine.

  15. A power function method for estimating base flow.

    Science.gov (United States)

    Lott, Darline A; Stewart, Mark T

    2013-01-01

    Analytical base flow separation techniques are often used to determine the base flow contribution to total stream flow. Most analytical methods derive base flow from discharge records alone without using basin-specific variables other than basin area. This paper derives a power function for estimating base flow, the form being aQ(b) + cQ, an analytical method calibrated against an integrated basin variable, specific conductance, relating base flow to total discharge, and is consistent with observed mathematical behavior of dissolved solids in stream flow with varying discharge. Advantages of the method are being uncomplicated, reproducible, and applicable to hydrograph separation in basins with limited specific conductance data. The power function relationship between base flow and discharge holds over a wide range of basin areas. It better replicates base flow determined by mass balance methods than analytical methods such as filters or smoothing routines that are not calibrated to natural tracers or empirical basin and gauge-specific variables. Also, it can be used with discharge during periods without specific conductance values, including separating base flow from quick flow for single events. However, it may overestimate base flow during very high flow events. Application of geochemical mass balance and power function base flow separation methods to stream flow and specific conductance records from multiple gauges in the same basin suggests that analytical base flow separation methods must be calibrated at each gauge. Using average values of coefficients introduces a potentially significant and unknown error in base flow as compared with mass balance methods. © 2012, The Author(s). Groundwater © 2012, National Ground Water Association.

  16. ESTIMATION OF SURVIVAL IN PATIENTS WITH ADVANCED OVARIAN CANCER – ABSTRACT OF THE RESEARCH PROJECT

    Directory of Open Access Journals (Sweden)

    Špela Smrkolj

    2018-02-01

    Full Text Available Background: Morbidity and mortality caused by cancer persist to be an important health problem world- wide and in the European Union member states as well. In Slovenia, most ovarian cancer cases are detected in advanced stages, hence a rather high mortality rate. Aims: The purpose of this research project is to analyze the primary cytoreduction in the patients with advanced ovarian cancer. The main objective of the project is to assess the use of lap- aroscopy in the prediction of optimal cytoreduction in these patients. Applicative research project ‘Estimation of survial in patients with advanced ovarian can- cer based on primary laparoscopical assessment of optimal cytoreduction’ (L3-2371 was approved and has been financed by the Slovene Research Agency and co-financed by the Ministry of Health of RS; Duration: May 1, 2009–April 30, 2012. Methods: The research project will consist of retrospective and prospective study. In all the patients with advanced ovarian cancer managed at the Department of Obstetrics and Gynecol- ogy, University Medical Centre Ljubljana in the years 2003–2008, and in whom optimal primary cytoreduction was made using either laparoscopy or laparotomy, certain clinical and pathomorphological factors will be compared, and the effects of all analyzed factors on the outcome of treatment assessed. In the prospective study, we will aim at assessing the use of laparoscopy in the prediction of optimal cytoreduction in all newly detected cases using a laparoscopy-based score (Fagotti’s scoring system. Conclusions: The standard management of advanced ovarian cancer patients consists of primary surgical optimal and/or suboptimal cytoreduction followed by aggressive cytotoxic chemotherapy. In line with our experience and with that published most recently, laparoscopy seems to be a promising method with which we will attempt to most accurately assess the optimal cytoreduction in surgical treatment of ovarian cancer patients.

  17. Up-to-date and projected estimates of survival for people with cystic fibrosis using baseline characteristics: A longitudinal study using UK patient registry data.

    Science.gov (United States)

    Keogh, Ruth H; Szczesniak, Rhonda; Taylor-Robinson, David; Bilton, Diana

    2018-01-05

    Cystic fibrosis (CF) is the most common inherited disease in Caucasians, affecting around 10,000 individuals in the UK today. Prognosis has improved considerably over recent decades with ongoing improvements in treatment and care. Providing up-to-date survival predictions is important for patients, clinicians and health services planning. Flexible parametric survival modelling of UK CF Registry data from 2011 to 2015, capturing 602 deaths in 10,428 individuals. Survival curves were estimated from birth; conditional on reaching older ages; and projected under different assumptions concerning future mortality trends, using baseline characteristics of sex, CFTR genotype (zero, one, two copies of F508del) and age at diagnosis. Male sex was associated with better survival, as was older age at diagnosis, but only in F508del non-homozygotes. Survival did not differ by genotype among individuals diagnosed at birth. Median survival ages at birth in F508del homozygotes were 46years (males) and 41years (females), and similar in non-homozygotes diagnosed at birth. F508del heterozygotes diagnosed aged 5 had median survival ages of 57 (males) and 51 (females). Conditional on survival to 30, median survival age rises to 52 (males) and 49 (females) in homozygotes. Mortality rates decreased annually by 2% during 2006-2015. Future improvements at this rate suggest median survival ages for F508del homozygous babies of 65 (males) and 56 (females). Over half of babies born today, and of individuals aged 30 and above today, can expect to survive into at least their fifth decade. Evidence before this study We searched PubMed with terms "(cystic fibrosis survival) and (projection OR model OR registry OR United Kingdom OR UK)" to identify relevant studies on survival estimates for individuals with cystic fibrosis (CF). We also considered the most recent annual report from the UK Cystic Fibrosis Registry (Cystic Fibrosis Trust, 2016), a review by Buzzetti and colleagues (2009), the chapter

  18. On nonparametric hazard estimation.

    Science.gov (United States)

    Hobbs, Brian P

    The Nelson-Aalen estimator provides the basis for the ubiquitous Kaplan-Meier estimator, and therefore is an essential tool for nonparametric survival analysis. This article reviews martingale theory and its role in demonstrating that the Nelson-Aalen estimator is uniformly consistent for estimating the cumulative hazard function for right-censored continuous time-to-failure data.

  19. On nonparametric hazard estimation

    OpenAIRE

    Hobbs, Brian P.

    2015-01-01

    The Nelson-Aalen estimator provides the basis for the ubiquitous Kaplan-Meier estimator, and therefore is an essential tool for nonparametric survival analysis. This article reviews martingale theory and its role in demonstrating that the Nelson-Aalen estimator is uniformly consistent for estimating the cumulative hazard function for right-censored continuous time-to-failure data.

  20. The Gemin associates of survival motor neuron are required for motor function in Drosophila.

    Directory of Open Access Journals (Sweden)

    Rebecca Borg

    Full Text Available Membership of the survival motor neuron (SMN complex extends to nine factors, including the SMN protein, the product of the spinal muscular atrophy (SMA disease gene, Gemins 2-8 and Unrip. The best-characterised function of this macromolecular machine is the assembly of the Sm-class of uridine-rich small nuclear ribonucleoprotein (snRNP particles and each SMN complex member has a key role during this process. So far, however, only little is known about the function of the individual Gemin components in vivo. Here, we make use of the Drosophila model organism to uncover loss-of-function phenotypes of Gemin2, Gemin3 and Gemin5, which together with SMN form the minimalistic fly SMN complex. We show that ectopic overexpression of the dead helicase Gem3(ΔN mutant or knockdown of Gemin3 result in similar motor phenotypes, when restricted to muscle, and in combination cause lethality, hence suggesting that Gem3(ΔN overexpression mimics a loss-of-function. Based on the localisation pattern of Gem3(ΔN, we predict that the nucleus is the primary site of the antimorphic or dominant-negative mechanism of Gem3(ΔN-mediated interference. Interestingly, phenotypes induced by human SMN overexpression in Drosophila exhibit similarities to those induced by overexpression of Gem3(ΔN. Through enhanced knockdown we also uncover a requirement of Gemin2, Gemin3 and Gemin5 for viability and motor behaviour, including locomotion as well as flight, in muscle. Notably, in the case of Gemin3 and Gemin5, such function also depends on adequate levels of the respective protein in neurons. Overall, these findings lead us to speculate that absence of any one member is sufficient to arrest the SMN-Gemins complex function in a nucleocentric pathway, which is critical for motor function in vivo.

  1. Estimating Supply Response Function for Wheat: A Case Study

    Directory of Open Access Journals (Sweden)

    M.S. EI-Habbab

    2002-01-01

    Full Text Available To increase wheat production, governments can subsidize wheat farmers by purchasing their produce at a price higher than the world price. This policy did not succeed in increasing wheat production in the Irbid Governorate of Jordan, our case study area. The agricultural sector in the study area was characterized by risk in production and prices. In our study, the supply response function based on the Nerlovian Model was estimated for wheat produced in Irbid Governorate. Wheat area, in the model, was the dependent variable in the supply response function. The independent variables were: wheat planted area in Dunums in the current and previous year respectively, the weighted price of wheat in the previous year deflated by the Consumer Price Index (CPI, the holding fragmentation coefficient in the previous year, the yield risk, and the amount of rain in millimeters during the early months of the season (October, November, and December. The study reached the following conclusions: Firstly, holdings fragmentation was the major factor that negatively affects wheat production. Since the heritage system is the main factor that affects holding fragmentation, the policy makers need to find a way that can decrease this effect. Secondly, lagged weighted prices were found more suitable than the current weighted prices from an economic and statical point of view. Thirdly, the partial adjustment coefficient was low (i.e. less than one, which means that the farmers need more than one year to change their producing habits. Finally, the farmers were found to be risk-neutral, because their decisions depend mainly on the level and distribution of rainfall during the rainy season.

  2. Estimation of Aedes aegypti (Diptera: Culicidae) population size and adult male survival in an urban area in Panama

    Science.gov (United States)

    Neira, Marco; Lacroix, Renaud; Cáceres, Lorenzo; Kaiser, Paul E; Young, Josue; Pineda, Lleysa; Black, Isaac; Sosa, Nestor; Nimmo, Derric; Alphey, Luke; McKemey, Andrew

    2014-01-01

    Traditional mosquito control strategies rely heavily on the use of chemical insecticides. However, concerns about the efficiency of traditional control methods, environmental impact and emerging pesticide resistance have highlighted the necessity for developing innovative tools for mosquito control. Some novel strategies, including release of insects carrying a dominant lethal gene (RIDL®), rely on the sustained release of modified male mosquitoes and therefore benefit from a thorough understanding of the biology of the male of the species. In this report we present the results of a mark-release-recapture study aimed at: (i) establishing the survival in the field of laboratory-reared, wild-type male Aedes aegypti and (b) estimating the size of the local adult Ae. aegypti population. The study took place in Panama, a country where recent increases in the incidence and severity of dengue cases have prompted health authorities to evaluate alternative strategies for vector control. Results suggest a life expectancy of 2.3 days for released male mosquitoes (confidence interval: 1.78-2.86). Overall, the male mosquito population was estimated at 58 males/ha (range 12-81 males/ha), which can be extrapolated to an average of 0.64 pupae/person for the study area. The practical implications of these results are discussed. PMID:25410991

  3. Protein kinase G1 α overexpression increases stem cell survival and cardiac function after myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Linlin Wang

    Full Text Available We hypothesized that overexpression of cGMP-dependent protein kinase type 1α (PKG1α could mimic the effect of tadalafil on the survival of bone marrow derived mesenchymal stem cells (MSCs contributing to regeneration of the ischemic heart.MSCs from male rats were transduced with adenoviral vector encoding for PKG1α ((PKG1αMSCs.Controls included native MSCs ((NatMSCs and MSCs transduced with an empty vector ((NullMSCs. PKG1α activity was increased approximately 20, 5 and 16 fold respectively in (PKG1αMSCs. (PKG1αMSCs showed improved survival under oxygen and glucose deprivation (OGD which was evidenced by lower LDH release, caspase-3/7 activity and number of positive TUNEL cells. Anti-apoptotic proteins pAkt, pGSK3β, and Bcl-2 were significantly increased in (PKG1αMSCs compared to (NatMSCs and (NullMSCs. Higher release of multiple prosurvival and angiogenic factors such as HGF, bFGF, SDF-1 and Ang-1 was observed in (PKG1αMSCs before and after OGD. In a female rat model of acute myocardial infarction, (PKG1αMSCs group showed higher survival compared with (NullMSCs group at 3 and 7 days after transplantation as determined by TUNEL staining and sry-gene quantitation by real-time PCR. Increased anti-apoptotic proteins and paracrine factors in vitro were also identified. Immunostaining for cardiac troponin I combined with GFP showed increased myogenic differentiation of (PKG1αMSCs. At 4 weeks after transplantation, compared to DMEM group and (NullMSCs group, (PKG1αMSCs group showed increased blood vessel density in infarct and peri-infarct areas (62.5±7.7; 68.8±7.3 per microscopic view, p<0.05 and attenuated infarct size (27.2±2.5%, p<0.01. Heart function indices including ejection fraction (52.1±2.2%, p<0.01 and fractional shortening (24.8%±1.3%, p<0.01 were improved significantly in (PKG1αMSCs group.Overexpression of PKG1α transgene could be a powerful approach to improve MSCs survival and their angiomyogenic potential in the

  4. Estimating Luminosity Function Constraints from High-Redshift Galaxy Surveys

    Science.gov (United States)

    Robertson, Brant E.

    2010-04-01

    The installation of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) will revolutionize the study of high-redshift galaxy populations. Initial observations of the HST Ultra Deep Field (UDF) have yielded multiple z >~ 7 dropout candidates. Supplemented by the GOODS Early Release Science (ERS) and further UDF pointings, these data will provide crucial information about the most distant known galaxies. However, achieving tight constraints on the z ~ 7 galaxy luminosity function (LF) will require even more ambitious photometric surveys. Using a Fisher matrix approach to fully account for Poisson and cosmic sample variance, as well as covariances in the data, we estimate the uncertainties on LF parameters achieved by surveys of a given area and depth. Applying this method to WFC3 z ~ 7 dropout galaxy samples, we forecast the LF parameter uncertainties for a variety of model surveys. We demonstrate that performing a wide area (~1 deg2) survey to H AB ~ 27 depth or increasing the UDF depth to H AB ~ 30 provides excellent constraints on the high-z LF when combined with the existing Ultradeep Field Guest Observation and GOODS ERS data. We also show that the shape of the matter power spectrum may limit the possible gain of splitting wide area (gsim0.5 deg2) high-redshift surveys into multiple fields to probe statistically independent regions; the increased rms density fluctuations in smaller volumes mostly offset the improved variance gained from independent samples.

  5. Estimated Green's function extracted from superconducting gravimeters and seismometers

    Science.gov (United States)

    Zeng, Xiangfang; Zhan, Zhongwen; Zheng, Yong

    2011-04-01

    Estimated Green's function (EGF) between stations has been extracted from ambient seismic noise, direct surface wave and coda waves. It is also confirmed by laboratory experiments on ultrasonics and theoretical derivations assuming diffusive wave field, equi-partition of modes or random sources on an enclosed surface. This method provides a new approach to study the crust and mantle structure at regional scale, continental scale and global scale. Following the achievements with seismometer records, the records of infrasonic station, hydrophone and microphone were also used to obtain the EGFs of different wave fields. Since superconducting gravimeter is a better long period instrument than regular seismometer, EGF at longer period is expected to be obtained with the cross correlation of gravity data. In this paper, we will show the EGFs extracted by cross-correlations between the superconducting gravimeters and the seismometers. Both the travel times and dispersion curves obtained from different data types are consistent. The result shows that it is possible to retrieve the deep structure by the cross correlation of gravity data.

  6. Estimation of Baroreflex Function Using Independent Component Analysis of Photoplethysmography

    Science.gov (United States)

    Abe, Makoto; Yoshizawa, Makoto; Sugita, Norihiro; Tanaka, Akira; Homma, Noriyasu; Yambe, Tomoyuki; Nitta, Shin-Ichi

    The maximum cross-correlation coefficient ρmax between blood pressure variability and heart rate variability, whose frequency components are limited to the Mayer wave-related band, is a useful index to evaluate the state of the autonomic nervous function related to baroreflex. However, measurement of continuous blood pressure with an expensive and bulky measuring device is required to calculate ρmax. The present study has proposed an easier method for obtaining ρmax with measurement of finger photoplethysmography (PPG) only. In the proposed method, independent components are extracted from feature variables specifying the PPG signal by using the independent component analysis (ICA), and then the most appropriate component is chosen out of them so that the ρmax calculated from the component can approximate its true value. The results from the experiment with a postural change performed in 18 healthy subjects have suggested that the proposed method is available for estimating ρmax by using the ICA to extract blood pressure information from the PPG signal.

  7. Survival Estimates for the Passage of Spring-Migrating Juvenile Salmonids through Snake and Columbia River Dams and Reservoirs, 2005-2006 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Steven G.; Muir, William D.; Marsh, Douglas M. (National Marine Fisheries Service, Northwest Fisheries Science Center, Fish Ecology Division, Seattle, WA)

    2006-05-01

    In 2005, the National Marine Fisheries Service and the University of Washington completed the thirteenth year of a study to estimate survival and travel time of juvenile salmonids Oncorhynchus spp. passing through dams and reservoirs on the Snake and Columbia Rivers. All estimates were derived from detections of fish tagged with passive integrated transponder tags (PIT tags). We PIT tagged and released a total of 18,439 hatchery steelhead, 5,315 wild steelhead, and 6,964 wild yearling Chinook salmon at Lower Granite Dam in the Snake River. In addition, we utilized fish PIT tagged by other agencies at traps and hatcheries upstream from the hydropower system and at sites within the hydropower system in both the Snake and Columbia Rivers. PIT-tagged smolts were detected at interrogation facilities at Lower Granite, Little Goose, Lower Monumental, Ice Harbor, McNary, John Day, and Bonneville Dams and in the PIT-tag detector trawl operated in the Columbia River estuary. Survival estimates were calculated using a statistical model for tag-recapture data from single release groups (the ''single-release model''). Primary research objectives in 2005 were: (1) Estimate reach survival and travel time in the Snake and Columbia Rivers throughout the migration period of yearling Chinook salmon O. tshawytscha and steelhead O. mykiss. (2) Evaluate relationships between survival estimates and migration conditions. (3) Evaluate the survival estimation models under prevailing conditions. This report provides reach survival and travel time estimates for 2005 for PIT-tagged yearling Chinook salmon (hatchery and wild), hatchery sockeye salmon O. nerka, hatchery coho salmon O. kisutch, and steelhead (hatchery and wild) in the Snake and Columbia Rivers. Additional details on the methodology and statistical models used are provided in previous reports cited here.

  8. Lipotoxicity in the Pancreatic Beta Cell: Not Just Survival and Function, but Proliferation as Well?

    Science.gov (United States)

    Sharma, Rohit B.; Alonso, Laura C.

    2014-01-01

    Free fatty acids (FFAs) exert both positive and negative effects on beta cell survival and insulin secretory function, depending on concentration, duration, and glucose abundance. Lipid signals are mediated not only through metabolic pathways, but also through cell surface and nuclear receptors. Toxicity is modulated by positive signals arising from circulating factors such as hormones, growth factors and incretins, as well as negative signals such as inflammatory mediators and cytokines. Intracellular mechanisms of lipotoxicity include metabolic interference and cellular stress responses such as oxidative stress, endoplasmic reticulum (ER) stress, and possibly autophagy. New findings strengthen an old hypothesis that lipids may also impair compensatory beta cell proliferation. Clinical observations continue to support a role for lipid biology in the risk and progression of both type 1 (T1D) and type 2 diabetes (T2D). This review summarizes recent work in this important, rapidly evolving field. PMID:24740729

  9. Salidroside, A Natural Antioxidant, Improves β-Cell Survival and Function via Activating AMPK Pathway

    Directory of Open Access Journals (Sweden)

    Linjie Ju

    2017-10-01

    Full Text Available Aim: The enhanced oxidative stress contributes to progression of type 2 diabetes mellitus (T2DM and induces β-cell failure. Salidroside is a natural antioxidant extracted from medicinal food plant Rhodiola rosea. This study was aimed to evaluate protective effects of salidroside on β-cells against diabetes associated oxidative stress.Methods and Results: In diabetic db/db and high-fat diet-induced mice, we found salidroside ameliorated hyperglycemia and relieved oxidative stress. More importantly, salidroside increased β-cell mass and β-cell replication of diabetic mice. Mechanism study in Min6 cells revealed that, under diabetic stimuli, salidroside suppressed reactive oxygen species production and restore mitochondrial membrane potential (ΔΨm via reducing NOX2 expression and inhibiting JNK–caspase 3 apoptotic cascade subsequently to protect β-cell survival. Simultaneously, diabetes associated oxidative stress also activated FOXO1 and triggered nuclear exclusion of PDX1 which resulted in β-cell dysfunction. This deleterious result was reversed by salidroside by activating AMPK-AKT to inhibit FOXO1 and recover PDX1 nuclear localization. The efficacy of salidroside in improving β-cell survival and function was further confirmed in isolated cultured mouse islets. Moreover, the protective effects of salidroside on β-cells against diabetic stimuli can be abolished by an AMPK inhibitor compound C, which indicated functions of salidroside on β-cells were AMPK activation dependent.Conclusion: These results confirmed beneficial metabolic effects of salidroside and identified a novel role for salidroside in preventing β-cell failure via AMPK activation. Our finding highlights the potential value of Rhodiola rosea as a dietary supplement for diabetes control.

  10. Salidroside, A Natural Antioxidant, Improves β-Cell Survival and Function via Activating AMPK Pathway.

    Science.gov (United States)

    Ju, Linjie; Wen, Xiaohua; Wang, Chunjun; Wei, Yingjie; Peng, Yunru; Ding, Yongfang; Feng, Liang; Shu, Luan

    2017-01-01

    Aim: The enhanced oxidative stress contributes to progression of type 2 diabetes mellitus (T2DM) and induces β-cell failure. Salidroside is a natural antioxidant extracted from medicinal food plant Rhodiola rosea. This study was aimed to evaluate protective effects of salidroside on β-cells against diabetes associated oxidative stress. Methods and Results: In diabetic db/db and high-fat diet-induced mice, we found salidroside ameliorated hyperglycemia and relieved oxidative stress. More importantly, salidroside increased β-cell mass and β-cell replication of diabetic mice. Mechanism study in Min6 cells revealed that, under diabetic stimuli, salidroside suppressed reactive oxygen species production and restore mitochondrial membrane potential (ΔΨm) via reducing NOX2 expression and inhibiting JNK-caspase 3 apoptotic cascade subsequently to protect β-cell survival. Simultaneously, diabetes associated oxidative stress also activated FOXO1 and triggered nuclear exclusion of PDX1 which resulted in β-cell dysfunction. This deleterious result was reversed by salidroside by activating AMPK-AKT to inhibit FOXO1 and recover PDX1 nuclear localization. The efficacy of salidroside in improving β-cell survival and function was further confirmed in isolated cultured mouse islets. Moreover, the protective effects of salidroside on β-cells against diabetic stimuli can be abolished by an AMPK inhibitor compound C, which indicated functions of salidroside on β-cells were AMPK activation dependent. Conclusion: These results confirmed beneficial metabolic effects of salidroside and identified a novel role for salidroside in preventing β-cell failure via AMPK activation. Our finding highlights the potential value of Rhodiola rosea as a dietary supplement for diabetes control.

  11. Cost and Benefit of Control Strategies - Estimation of Benefit functions, enforcement-probability function and enforcement-cost function

    DEFF Research Database (Denmark)

    Kronbak, Lone Grønbæk; Jensen, Frank

    levels and 4) the connection between different enforcement levels and costs. The purpose of estimating the functional relationships are for future application in the COBECOS computer modeling in order to carry out an cost-benefit analysis of control strategies and thereby find the optimal mix and level...

  12. Optimal estimation of the intensity function of a spatial point process

    DEFF Research Database (Denmark)

    Guan, Yongtao; Jalilian, Abdollah; Waagepetersen, Rasmus

    easily computable estimating functions. We derive the optimal estimating function in a class of first-order estimating functions. The optimal estimating function depends on the solution of a certain Fredholm integral equation and reduces to the likelihood score in case of a Poisson process. We discuss...... the numerical solution of the Fredholm integral equation and note that a special case of the approximated solution is equivalent to a quasi-likelihood for binary spatial data. The practical performance of the optimal estimating function is evaluated in a simulation study and a data example....

  13. Estimation of reduced partition function ratios of lithium-graphite intercalation compounds by density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Kunihiko; Saito, Shun; Yanase, Satoshi; Oi, Takao [Sophia Univ., Tokyo (Japan). Faculty of Science and Technology

    2014-03-15

    The reduced partition function ratio (RPFR) of lithium in lithium-graphite intercalation compounds (Li-GICs) was evaluated at the UB3LYP/6-311G(d) level of theory. The partition functions were written in the usual rigid-rotor harmonic oscillator approximation. With a C{sub 24}H{sub 12} coronene molecule as the model of graphene, lithium-coronene sandwich, and club sandwich compounds were considered as models of Li-GICs. The estimated value of the {sup 6}Li-to-{sup 7}Li RPFR was 1.0402 at 25 C, which yielded 1.034 as the value of the equilibrium constant, K, of the lithium isotope exchange reaction between a lithium ion in an ethylene carbonate/ethylmethyl carbonate mixed solvent and a lithium atom in interlayer space of graphite. The estimated value of K was larger than the experimental value of 1.025. The unsatisfactory agreement between the estimated and experimental K values suggested that larger molecules should be used as models of graphene and that the vibrational anharmonicity should also be taken into consideration. (orig.)

  14. Topological estimation of aerodynamic controlled airplane system functionality of quality

    Directory of Open Access Journals (Sweden)

    С.В. Павлова

    2005-01-01

    Full Text Available  It is suggested to use topological methods for stage estimation of aerodynamic airplane control in widespread range of its conditions The estimation is based on normalized stage virtual non-isotropy of configurational airplane systems calculation.

  15. Survival of timber rattlesnakes (Crotalus horridus) estimated by capture-recapture models in relation to age, sex, color morph, time, and birthplace

    Science.gov (United States)

    Brown, W.S.; Kery, M.; Hines, J.E.

    2007-01-01

    Juvenile survival is one of the least known elements of the life history of many species, in particular snakes. We conducted a mark–recapture study of Crotalus horridus from 1978–2002 in northeastern New York near the northern limits of the species' range. We marked 588 neonates and estimated annual age-, sex-, and morph-specific recapture and survival rates using the Cormack-Jolly-Seber (CJS) model. Wild-caught neonates (field-born, n  =  407) and neonates produced by captive-held gravid females (lab-born, n  =  181) allowed comparison of the birthplace, or lab treatment effect, in estimated survival. Recapture rates declined from about 10–20% over time while increasing from young to older age classes. Estimated survival rates (S ± 1 SE) in the first year were significantly higher among field-born (black morph: S  =  0.773 ± 0.203; yellow morph: S  =  0.531 ± 0.104) than among lab-born snakes (black morph: S  =  0.411 ± 0.131; yellow morph: S  =  0.301 ± 0.081). Lower birth weights combined with a lack of field exposure until release apparently contributed to the lower survival rate of lab-born snakes. Subsequent survival estimates for 2–4-yr-old snakes were S  =  0.845 ± 0.084 for the black morph and S  =  0.999 (SE not available) for the yellow morph, and for ≥5-yr-old snakes S  =  0.958 ± 0.039 (black morph) and S  =  0.822 ± 0.034 (yellow morph). The most parsimonious model overall contained an independent time trend for survival of each age, morph, and lab-treatment group. For snakes of the first two age groups (ages 1 yr and 2–4 yr), survival tended to decline over the years for both morphs, while for adult snakes (5 yr and older), survival was constant or even slightly increased. Our data on survival and recapture are among the first rigorous estimates of these parameters in a rattlesnake and among the few yet available for any viperid snake. These data are useful for analyses of the life

  16. Bacterial genotoxin functions as immune-modulator and promotes host survival

    Directory of Open Access Journals (Sweden)

    Riccardo Guidi

    2016-07-01

    Full Text Available Bacterial genotoxins are effectors that cause DNA damage in target cells. Many aspects of the biology of these toxins have been characterised in vitro, such as structure, cellular internalisation pathways and effects on the target cells. However, little is known about their function in vivo. Salmonella enterica serovar Typhi (S. Typhi is a Gram-negative, intracellular bacterium that causes typhoid fever, a debilitating disease infecting more than 20 million people every year. S. Typhi produce a genotoxin named typhoid toxin (TT, but its role in the contest of host infection is poorly characterized. The major obstacle in addressing this issue is that S. Typhi is exclusively a human pathogen. To overcome this limitation, we have used as model bacterium S. Typhimurium, and engineered it to produce endogenous levels of an active and inactive typhoid toxin, hereby named as TT (or genotoxic and cdtB (or control, respectively. To our surprise, infection with the genotoxin strain strongly suppressed intestinal inflammation, leading to a better survival of the host during the acute phase of infection, suggesting typhoid toxin may exert a protective role. The presence of a functional genotoxin was also associated with an increased frequency of asymptomatic carriers.

  17. Therapeutic Inhibition of miR-208a Improves Cardiac Function and Survival During Heart Failure

    Science.gov (United States)

    Montgomery, Rusty L.; Hullinger, Thomas G.; Semus, Hillary M.; Dickinson, Brent A.; Seto, Anita G.; Lynch, Joshua M.; Stack, Christianna; Latimer, Paul A.; Olson, Eric N.; van Rooij, Eva

    2012-01-01

    Background Diastolic dysfunction in response to hypertrophy is a major clinical syndrome with few therapeutic options. MicroRNAs act as negative regulators of gene expression by inhibiting translation or promoting degradation of target mRNAs. Previously, we reported that genetic deletion of the cardiac-specific miR-208a prevents pathological cardiac remodeling and upregulation of Myh7 in response to pressure overload. Whether this miRNA might contribute to diastolic dysfunction or other forms of heart disease is currently unknown. Methods and Results Here, we show that systemic delivery of an antisense oligonucleotide induces potent and sustained silencing of miR-208a in the heart. Therapeutic inhibition of miR-208a by subcutaneous delivery of antimiR-208a during hypertension-induced heart failure in Dahl hypertensive rats dose-dependently prevents pathological myosin switching and cardiac remodeling while improving cardiac function, overall health, and survival. Transcriptional profiling indicates that antimiR-208a evokes prominent effects on cardiac gene expression; plasma analysis indicates significant changes in circulating levels of miRNAs on antimiR-208a treatment. Conclusions These studies indicate the potential of oligonucleotide-based therapies for modulating cardiac miRNAs and validate miR-208 as a potent therapeutic target for the modulation of cardiac function and remodeling during heart disease progression. PMID:21900086

  18. Estimated glucose disposal rate and long-term survival in type 2 diabetes after coronary artery bypass grafting.

    Science.gov (United States)

    Nyström, Thomas; Holzmann, Martin J; Eliasson, Björn; Svensson, Ann-Marie; Kuhl, Jeanette; Sartipy, Ulrik

    2017-03-01

    We performed a nationwide population-based cohort study to investigate the association between estimated glucose disposal rate (eGDR) and long-term survival after coronary artery bypass grafting (CABG) in patients with type 2 diabetes. All patients who underwent primary CABG in Sweden from 2006 to 2013 were identified from the SWEDEHEART register and by record linkage to the National Diabetes Register; all patients with type 2 diabetes were included and formed the study population. Patients were followed until 2013 through national registers for major adverse cardiovascular events and death from any cause. eGDR was calculated using waist circumference, hemoglobin A1c, and presence or the absence of hypertension. The association between eGDR and death was estimated using multivariable Cox regression. A total of 3256 patients were included. During a mean follow-up of 3.1 years (10,227 person-years), in total, 14 % patients died: 17 % (n = 186) in the 1st tertile (lowest eGDR), 14 % (n = 145) in the 2nd tertile, and 13 % (n = 133) in the 3rd tertile (highest eGDR). There was a significant association between eGDR and increased risk of death: adjusted hazard ratio (95 % confidence interval): 1.46 (1.12-1.90) for the 1st eGDR tertile compared to the 3rd and highest eGDR tertile. In conclusion, patients with type 2 diabetes who underwent CABG, a low eGDR, were associated with an increased risk of long-term all-cause mortality that was independent of other cardiovascular and metabolic risk factors. Insulin resistance measured by eGDR could be a useful risk marker in patients with type 2 diabetes and ischemic heart disease.

  19. Treatment of base of tongue cancer, stage III and stage IV with primary surgery: survival and functional outcomes.

    Science.gov (United States)

    Al-Qahtani, Khaled; Rieger, Jen; Harris, Jeffery R; Mlynarek, Alex; Williams, David; Islam, Tahera; Seikaly, Hadi

    2015-08-01

    This study examines functional outcome (speech and swallowing), survival, and disease control in patients receiving an intensified treatment regimen with primary aggressive surgery, and postoperative radiotherapy or postoperative concomitant chemoradiotherapy, for previously untreated, resectable, stage III and IV squamous cell carcinoma (SCC) of the tongue base. Sixty-six consecutive patients treated from June 1997 to June 2006 were followed prospectively through the Multidisciplinary Head and Neck Surgery Reconstruction Clinic. Speech and swallowing data were gathered at four evaluation times during the first year. Speech assessment was conducted by PERCI, Nasometer, and C-AIDS and swallowing assessment by Modified barium swallow, Diet survey and G-tube. Also, the overall survival, disease-specific survival and loco regional control were measured. The average age of the patients was 56.8, 85 % male and 15 % female. All patients had primary surgical resection and 83 % received postoperative radiotherapy and 17 % chemoradiation therapy. Overall survival at 3 years was 80.3 % and 5 years 52.2 %. Disease-specific survival at 3 years was 86.7 % and 5 years was 77.5 %. Local control was 94 %. Distal metastasis and second primary were found to be 7.5 % each. Primary surgical treatment of advanced BOT cancer offers excellent functional outcome, local control and disease-specific survival.

  20. Bounds Estimation Via Regression with Asymmetric Cost Functions

    Science.gov (United States)

    DeCoste, D.

    1997-01-01

    This paper addresses a significant but mostly-neglected class of problems that we call bounds estimation. This includes learning empirical best-case and worst-case algorithmic complexity bounds and red-line bounds on sensor data.

  1. Use of individual colour-ringing to estimate annual survival in male and female Red Knot Calidris canutus islandica : a progress report for 1998–2001

    NARCIS (Netherlands)

    Brochard, Christophe; Spaans, Bernard; Prop, Jouke; Piersma, Theunis

    2002-01-01

    In relatively long-lived birds like shorebirds, even small changes in adult mortality may affect population size. However, annual survival estimates based on metal-ringing and accumulating recoveries by the general public take at least a decade to materialise. To try and obtain faster and more

  2. A meta-analysis of clinical studies to estimate the 4.5-year survival rate of implants placed with the osteotome technique.

    NARCIS (Netherlands)

    Shalabi, M.M.; Manders, P.; Mulder, J.; Jansen, J.A.; Creugers, N.H.J.

    2007-01-01

    PURPOSE: To estimate the survival rate of implants placed with the osteotome technique by means of a systematic review. MATERIALS AND METHODS: The literature was searched using Medline; the search was limited to the years 1953 to 2005. Inclusion criteria were: (1) clinical studies or clinical

  3. Survival of the functional yeast Kluyveromyces marxianus B0399 in fermented milk with added sorbic acid.

    Science.gov (United States)

    Tabanelli, G; Verardo, V; Pasini, F; Cavina, P; Lanciotti, R; Caboni, M F; Gardini, F; Montanari, C

    2016-01-01

    In this study, the survival of the functional yeast Kluyveromyces marxianus B0399 in an industrially produced fermented milk was evaluated. In particular, the yeast viability was assessed throughout the entire shelf-life of the product (30 d) to ensure the presence of the effective yeast dose (20 million viable cells for each serving of 125 g) while avoiding, by sorbic acid addition, yeast growth, which could affect product quality and stability. To find the best combination of yeast and sorbic acid concentration, 13 different combinations were tested, and then 2 of them were chosen for industrial production. In production at lower concentrations (30 million viable cells, 150 mg/kg of sorbic acid) the effective dose was maintained only at 4 and 6°C, whereas at higher dosages (70 million viable cells, 250 mg/kg of sorbic acid) the effect of temperature was less evident. In all the trials, the concentration of sorbic acid was not affected by microbial metabolism and remained stable throughout the entire shelf-life. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  4. Estimation of functional preparedness of young handballers in setup time

    Directory of Open Access Journals (Sweden)

    Favoritоv V.N.

    2012-11-01

    Full Text Available The dynamics of level of functional preparedness of young handballers in setup time is shown. It was foreseen to make alteration in educational-training process with the purpose of optimization of their functional preparedness. 11 youths were plugged in research, calendar age 14 - 15 years. For determination of level of their functional preparedness the computer program "SVSM" was applied. It is set that at the beginning of setup time of 18,18% of all respondent functional preparedness is characterized by a "middle" level, 27,27% - below the "average", 54,54% - "above" the average. At the end of setup time among sportsmen representatives prevailed with the level of functional preparedness "above" average - 63,63%, with level "high" - 27,27%, sportsmen with level below the average were not observed. Efficiency of the offered system of trainings employments for optimization of functional preparedness of young handballers is well-proven.

  5. Software Functional Size: For Cost Estimation and More

    Science.gov (United States)

    Ozkan, Baris; Turetken, Oktay; Demirors, Onur

    Determining software characteristics that will effectively support project planning, execution, monitoring and closure remains to be one of the prevalent challenges software project managers face. Functional size measures were introduced to quantify one of the primary characteristics of software. Although functional size measurement methods have not been without criticisms, they have significant promises for software project management. In this paper, we explore the contributions of functional size measurement to project management. We identified diverse uses of functional size by performing a literature survey and investigating how functional size measurement can be incorporated into project management practices by mapping the uses of functional size to the knowledge areas defined in project management body of knowledge (PMBOK).

  6. [Restoration of the complicated locomotor functions of the upper extremities in the patients surviving ischemic stroke].

    Science.gov (United States)

    Bondarenko, F V; Makarova, M R; Turova, E A

    2016-01-01

    During the late and residual periods of stroke, it is necessary to pay attention to the training of complex spatial movements along with the traditional restoration of the balance and strength of para-articular muscles and the mobility of the paretic limb joints. The objective of the present study was to evaluate the effectiveness of robotic therapy for the recovery of the functions of the upper extremities in the late and residual periods of stroke. The study involved 52 patients who had survived ischemic stroke in the middle cerebral artery. The patients were divided randomly into 2 groups. All of them performed therapeutic physical exercises based on the standard technique during 5 days a week for 3 weeks. In addition, the treatment included massage, laser and pulsed current therapy. The patients of the main group (n=36) were additionally trained to perform complex spatial movements with special emphasis on their speed, fluidity, precision, and agility with the use of the Multi Joint System (MJS) robotic electromechanical device (40 min, 5 days/wk x 3wk). The analysis of the results of the study has demonstrated the statistically significant difference in the degree of improvement of the range of motion (ROM) in the elbow and shoulder joints, the speed and the accuracy of these movements between the patients of the main and control groups. It is concluded that the instrumental restoration of complex spatial movements of the upper extremities during the late and residual periods of stroke contributes not only to the improvement of the functional capabilities but also to the enhancement of independence and personal adjustment of the stroke patients.

  7. Improving Survival and Promoting Respiratory Motor Function After Cervical Spinal Cord Injury

    Science.gov (United States)

    2017-09-01

    This application proposes to help improve survival, decrease early dependence on mechanical ventilation, and restore breathing after cervical spinal...complications. This application proposes to help improve survival, decrease early dependence on mechanical ventilation, and restore breathing after...training as cervical SCI is a complicated and difficult surgery and much practice is needed in order to produce consistent injury outcomes

  8. Modelling survival

    DEFF Research Database (Denmark)

    Ashauer, Roman; Albert, Carlo; Augustine, Starrlight

    2016-01-01

    well GUTS, calibrated with short-term survival data of Gammarus pulex exposed to four pesticides, can forecast effects of longer-term pulsed exposures. Thirdly, we tested the ability of GUTS to estimate 14-day median effect concentrations of malathion for a range of species and use these estimates...

  9. Comprehensive discard reconstruction and abundance estimation using flexible selectivity functions

    NARCIS (Netherlands)

    Aarts, G.M.; Poos, J.J.

    2009-01-01

    The additional mortality caused by discarding may hamper the sustainable use of marine resources, especially if it is not accounted for in stock assessment and fisheries management. Generally, long and precise time-series on age-structured landings exist, but historical discard estimates are often

  10. Estimating Functions of Distributions Defined over Spaces of Unknown Size

    Directory of Open Access Journals (Sweden)

    David H. Wolpert

    2013-10-01

    Full Text Available We consider Bayesian estimation of information-theoretic quantities from data, using a Dirichlet prior. Acknowledging the uncertainty of the event space size m and the Dirichlet prior’s concentration parameter c, we treat both as random variables set by a hyperprior. We show that the associated hyperprior, P(c, m, obeys a simple “Irrelevance of Unseen Variables” (IUV desideratum iff P(c, m = P(cP(m. Thus, requiring IUV greatly reduces the number of degrees of freedom of the hyperprior. Some information-theoretic quantities can be expressed multiple ways, in terms of different event spaces, e.g., mutual information. With all hyperpriors (implicitly used in earlier work, different choices of this event space lead to different posterior expected values of these information-theoretic quantities. We show that there is no such dependence on the choice of event space for a hyperprior that obeys IUV. We also derive a result that allows us to exploit IUV to greatly simplify calculations, like the posterior expected mutual information or posterior expected multi-information. We also use computer experiments to favorably compare an IUV-based estimator of entropy to three alternative methods in common use. We end by discussing how seemingly innocuous changes to the formalization of an estimation problem can substantially affect the resultant estimates of posterior expectations.

  11. Estimation of reference values for liver function test analytes in ...

    African Journals Online (AJOL)

    The piccolo expressanalyzer screened for Albumin, Alanine Transaminase (ALT), AspartateTransaminase (AST), Total Protein (TP), Gamma Glutamine Transferase (GGT) and Total Bilirubin (TBIL). Results: Reference ranges were constructed using non-parametric methods to estimate 2.5 and 97.5 percentiles of distribution ...

  12. Multivariable Frequency Response Functions Estimation for Industrial Robots

    NARCIS (Netherlands)

    Hardeman, T.; Aarts, Ronald G.K.M.; Jonker, Jan B.

    2005-01-01

    The accuracy of industrial robots limits its applicability for high demanding processes, like robotised laser welding. We are working on a nonlinear exible model of the robot manipulator to predict these inaccuracies. This poster presents the experimental results on estimating the Multivariable

  13. Micro-Economic Estimation On The Demand Function For ...

    African Journals Online (AJOL)

    The article focused on the estimation of the prostitution demand behaviour in Adamawa State. An econometric model was specified based on economic theory and confronted with both primary and secondary data. Ordinary least square multiple regression techniques were adopted and the linear model was chosen as a ...

  14. Estimate of K-functionals and modulus of smoothness constructed ...

    Indian Academy of Sciences (India)

    Using a generalized spherical mean operator, we define generalized modulus of smoothness in the space L k 2 ( R d ) . Based on the Dunkl operator we define Sobolev-type space and -functionals. The main result of the paper is the proof of the equivalence theorem for a -functional and a modulus of smoothness for the ...

  15. Source Estimation for the Damped Wave Equation Using Modulating Functions Method: Application to the Estimation of the Cerebral Blood Flow

    KAUST Repository

    Asiri, Sharefa M.

    2017-10-19

    In this paper, a method based on modulating functions is proposed to estimate the Cerebral Blood Flow (CBF). The problem is written in an input estimation problem for a damped wave equation which is used to model the spatiotemporal variations of blood mass density. The method is described and its performance is assessed through some numerical simulations. The robustness of the method in presence of noise is also studied.

  16. Absolute Monotonicity of Functions Related To Estimates of First Eigenvalue of Laplace Operator on Riemannian Manifolds

    Directory of Open Access Journals (Sweden)

    Feng Qi

    2014-10-01

    Full Text Available The authors find the absolute monotonicity and complete monotonicity of some functions involving trigonometric functions and related to estimates the lower bounds of the first eigenvalue of Laplace operator on Riemannian manifolds.

  17. Expression of nerve growth factor carried by pseudotyped lentivirus improves neuron survival and cognitive functional recovery of post-ischemia in rats.

    Science.gov (United States)

    Cao, Jia-Yu; Lin, Yong; Han, Yan-Fei; Ding, Sheng-Hao; Fan, Yi-Ling; Pan, Yao-Hua; Zhao, Bing; Guo, Qin-Hua; Sun, Wen-Hua; Wan, Jie-Qing; Tong, Xiao-Ping

    2018-02-06

    Nerve growth factor (NGF) has been reported to prevent neuronal damage and contributes to the functional recovery in animal brain injury models and human ischemic disease as well. We aimed to investigate a potential therapeutic effect of NGF gene treatment in ischemic stroke and to estimate the functional recovery both at the cellular and cognitive levels in an ischemia rat model. After microinjection of pseudolentivirus-delivered β-NGF into an established ischemic stroke model in rats (tMCAO), we estimated neuronal cell apoptosis with TUNEL labeling and neurogenesis by cell proliferation marker Ki67 staining in both ischemic core and penumbra of striatum. Furthermore, we used behavioral functional tests, Morris water maze performance, to evaluate cognitive functional recovery in vivo and propose a potential underlying mechanism. We found that pseudolentivirus-mediated delivery of β-NGF gene into the brain induced high expression in striatum of the infarct core area after ischemia in rats. The β-NGF overexpression in the striatal infarction core after ischemia not only improved neuronal survival by reducing cell apoptosis and increasing cell proliferation, but also rescued cognitive functional impairment through upregulation of GAP-43 protein expression in tMCAO rat model of ischemia. This study demonstrates a potential β-NGF gene therapy by utilization of pseudolentivirus in ischemia and indicates future applications of NGF gene treatment in ischemic patients. © 2018 John Wiley & Sons Ltd.

  18. Production Functions for Water Delivery Systems: Analysis and Estimation Using Dual Cost Function and Implicit Price Specifications

    Science.gov (United States)

    Teeples, Ronald; Glyer, David

    1987-05-01

    Both policy and technical analysis of water delivery systems have been based on cost functions that are inconsistent with or are incomplete representations of the neoclassical production functions of economics. We present a full-featured production function model of water delivery which can be estimated from a multiproduct, dual cost function. The model features implicit prices for own-water inputs and is implemented as a jointly estimated system of input share equations and a translog cost function. Likelihood ratio tests are performed showing that a minimally constrained, full-featured production function is a necessary specification of the water delivery operations in our sample. This, plus the model's highly efficient and economically correct parameter estimates, confirms the usefulness of a production function approach to modeling the economic activities of water delivery systems.

  19. Distributed Sharing of Functionalities and Resources in Survivable GMPLS-controlled WSONs

    DEFF Research Database (Denmark)

    Fagertun, Anna Manolova; Cerutti, I.; Muñoz, R.

    2012-01-01

    at the physical layer (i.e., quality of transmission, QoT) and at the upper layer also in the case of a failure (i.e., survivability). This paper aims to apply the sharing concept to a WSON with QoT and survivability requirements (against single-link failures). QoT is guaranteed by resorting to regeneration...... is exploited to ensure survivability against single-link failures and make the sharing of network resources (regenerators and wavelengths) possible. The paper presents a novel distributed scheme (DISTR) for reservation of regenerators and wavelengths in generalized multi-protocol label switching controlled...... WSONs, in order to ensure the required level of QoT and survivability. Novel objects and selection strategies for the resource reservation protocol with traffic engineering extensions are proposed and evaluated. The DISTR scheme effectively combines regeneration and WC points, leading to a noticeable...

  20. Survival language learning syllabuses revisited: a customized functional-notional approach

    OpenAIRE

    Miranda Garc??a, Antonio; Calle Mart??n, Javier; S??ez Melendo, Ana Bel??n

    2006-01-01

    Research on survival English syllabuses has been scarce in the last decades. There is nothing worse than the solitude of a teacher facing a course with such characteristics as continuous hesitations about the materials, activities and the learners??? needs arise every now and then. Our contribution stems from Nation and Crabbe???s article ???A Survival Language Learning Syllabus for Foreign Travel??? published in System in 1991, where a topic-based syllabus is proposed. The two...

  1. Estimation of Survival Probabilities for Use in Cost-effectiveness Analyses: A Comparison of a Multi-state Modeling Survival Analysis Approach with Partitioned Survival and Markov Decision-Analytic Modeling.

    Science.gov (United States)

    Williams, Claire; Lewsey, James D; Mackay, Daniel F; Briggs, Andrew H

    2017-05-01

    Modeling of clinical-effectiveness in a cost-effectiveness analysis typically involves some form of partitioned survival or Markov decision-analytic modeling. The health states progression-free, progression and death and the transitions between them are frequently of interest. With partitioned survival, progression is not modeled directly as a state; instead, time in that state is derived from the difference in area between the overall survival and the progression-free survival curves. With Markov decision-analytic modeling, a priori assumptions are often made with regard to the transitions rather than using the individual patient data directly to model them. This article compares a multi-state modeling survival regression approach to these two common methods. As a case study, we use a trial comparing rituximab in combination with fludarabine and cyclophosphamide v. fludarabine and cyclophosphamide alone for the first-line treatment of chronic lymphocytic leukemia. We calculated mean Life Years and QALYs that involved extrapolation of survival outcomes in the trial. We adapted an existing multi-state modeling approach to incorporate parametric distributions for transition hazards, to allow extrapolation. The comparison showed that, due to the different assumptions used in the different approaches, a discrepancy in results was evident. The partitioned survival and Markov decision-analytic modeling deemed the treatment cost-effective with ICERs of just over £16,000 and £13,000, respectively. However, the results with the multi-state modeling were less conclusive, with an ICER of just over £29,000. This work has illustrated that it is imperative to check whether assumptions are realistic, as different model choices can influence clinical and cost-effectiveness results.

  2. HEDONIC PRICE FUNCTION ESTIMATION FOR MOBILE PHONE IN IRAN

    Directory of Open Access Journals (Sweden)

    Sayed Mahdi Mostafavi

    2013-01-01

    Full Text Available The aim of this paper is the survey of mobile price determinants by hedonic model. We have applied the hedonic price model for mobile phone market in Iran in the year of 2008. The brands conclude NOKIA, QTEK, HTC, MOTOROLA, SONY ERICSSON and SAMSUNG that comprise 193 types of handset mobile phone. The results show that in the hedonic function, the maximum amount of parameters of hedonic price function related to the following variables respectively: touch screen, hands free and connectivity tools, and the minimum amount of them are belonged to clarification of monitor images, phone volume and phone memory. Moreover, except Motorola brand the type of brand has not a significant parameter in the hedonic price function.

  3. Bayesian Nonparametric Mixture Estimation for Time-Indexed Functional Data in R

    Directory of Open Access Journals (Sweden)

    Terrance D. Savitsky

    2016-08-01

    Full Text Available We present growfunctions for R that offers Bayesian nonparametric estimation models for analysis of dependent, noisy time series data indexed by a collection of domains. This data structure arises from combining periodically published government survey statistics, such as are reported in the Current Population Study (CPS. The CPS publishes monthly, by-state estimates of employment levels, where each state expresses a noisy time series. Published state-level estimates from the CPS are composed from household survey responses in a model-free manner and express high levels of volatility due to insufficient sample sizes. Existing software solutions borrow information over a modeled time-based dependence to extract a de-noised time series for each domain. These solutions, however, ignore the dependence among the domains that may be additionally leveraged to improve estimation efficiency. The growfunctions package offers two fully nonparametric mixture models that simultaneously estimate both a time and domain-indexed dependence structure for a collection of time series: (1 A Gaussian process (GP construction, which is parameterized through the covariance matrix, estimates a latent function for each domain. The covariance parameters of the latent functions are indexed by domain under a Dirichlet process prior that permits estimation of the dependence among functions across the domains: (2 An intrinsic Gaussian Markov random field prior construction provides an alternative to the GP that expresses different computation and estimation properties. In addition to performing denoised estimation of latent functions from published domain estimates, growfunctions allows estimation of collections of functions for observation units (e.g., households, rather than aggregated domains, by accounting for an informative sampling design under which the probabilities for inclusion of observation units are related to the response variable. growfunctions includes plot

  4. Clinical use of estimated glomerular filtration rate for evaluation of kidney function

    DEFF Research Database (Denmark)

    Broberg, Bo; Lindhardt, Morten; Rossing, Peter

    2013-01-01

    Estimating glomerular filtration rate by the Modification of Diet in Renal Disease or Chronic Kidney Disease Epidemiology Collaboration formulas gives a reasonable estimate of kidney function for e.g. classification of chronic kidney disease. Additionally the estimated glomerular filtration rate...

  5. Sanotyping in estimation of functional abilities of the athlete's organism

    OpenAIRE

    Romanchuk, A.P.

    2015-01-01

    With the use of express polyfunctional methods of organism research - cardiorythmography, spirometery, laser cross-correlation spectroscopy and computing of motions - the sanotyping model of sportsmen organism functioning is got. The features of sanotypes sportsmen are marked specialized in playing kinds, heavy athletics, at run, boxing, kikboxing, swimming.

  6. On optimality of the empirical distribution function for the estimation ...

    African Journals Online (AJOL)

    Administrateur

    †Department of Information Technology and Mathematical Methods, Viale Marconi 5,. I-24044 Dalmine (BG), e-mail: ..... Note that when y = x the function RS defined by equation (6) can be rewritten as. RS(x, x)=4ES .... Van der Vaart and Van Zanten, (2005) have established the following general result. The process ηS.

  7. Estimate of K-functionals and modulus of smoothness constructed ...

    Indian Academy of Sciences (India)

    Introduction and preliminaries. In [2], Belkina and Platonov proved the equivalence theorem for a K-functional and a modulus of smoothness for the Dunkl transform in the Hilbert space L2(R, |x|2α+1. ), α > −1/2, using a Dunkl translation operator. In this paper, we prove the analog of this result (see [2]) in the Hilbert space.

  8. Purified mouse dopamine neurons thrive and function after transplantation into brain but require novel glial factors for survival in culture.

    Science.gov (United States)

    Donaldson, A E; Marshall, C E; Yang, Ming; Suon, S; Iacovitti, Lorraine

    2005-12-01

    Cell replacement therapy in Parkinson's disease depends on a reliable source of purified dopamine (DA) neurons (PDN) and the identification of factors relevant to their survival. Our goal was to genetically tag and purify by flow cytometry embryonic midbrain DA neurons from a transgenic mouse line carrying 11 kb of human tyrosine hydroxylase promoter driving expression of the enhanced green fluorescent protein(GFP) for studies in vivo and in vitro. A 99% purification of GFP+ cells was achieved. When transplanted into 6-hydroxydopamine-treated rat striatum, PDN survived, became well-integrated and produced recovery from amphetamine-induced motor behaviors. However, when grown in culture, PDN died within days of plating. No known growth factors prevented PDN death as did incubation with novel factors in glia/glial-conditioned media. We conclude that GFP-tagged DA neurons can be purified to homogeneity and can survive and function when grown with glial factors in vitro or after transplantation in vivo.

  9. Incorporating loss to follow-up in estimates of survival among HIV-infected individuals in sub-Saharan Africa enrolled in antiretroviral therapy programs.

    Science.gov (United States)

    Verguet, Stéphane; Lim, Stephen S; Murray, Christopher J L; Gakidou, Emmanuela; Salomon, Joshua A

    2013-01-01

    Measuring the survival of human immunodeficiency virus-infected adult patients enrolled in antiretroviral therapy (ART) programs is complicated by short observation periods and loss to follow-up. We synthesized data from treatment cohorts in sub-Saharan Africa to estimate survival over 5 years after initiation of ART. We used data on retention, mortality, and loss to follow-up from 34 cohorts, including a total of 102,306 adult patients from 18 sub-Saharan African countries. These data were augmented by data from 13 sub-Saharan African studies tracking death rates among adult patients who were lost to follow-up (LTFU). We used a Poisson regression model to estimate survival over time, incorporating predicted mortality among LTFU patients. Across studies, the median CD4(+) cell count at ART initiation was 104 cells/mm(3), 65% of patients were female, and the median age was 37 years. Survival at 1 year and 5 years were estimated to be 0.87 (95% confidence interval [CI], 0.72-0.94) and 0.70 (95% CI, 0.36-0.86), respectively, after adjustment for loss to follow-up. The life-years gained by a patient during the 5-year period after starting ART were estimated at 2.1 (95% CI, 1.6-2.3) in the adjusted model, compared with 1.7 (95% CI, 1.1-2.0) if there was 100% mortality among LTFU patients and with 2.4 (1.7-2.7) if there was 0% mortality among LTFU patients. Accounting for loss to follow-up produces substantial changes in the estimated life-years gained during the first 5 years of ART receipt.

  10. [Estimation of the number of minimum salaries attributed to professions in function of their prestige].

    Science.gov (United States)

    Sousa, F A; da Silva, J A

    2000-04-01

    The purpose of this study was to verify the relationship between professional prestige scaled through estimations and the professional prestige scaled through estimation of the number of minimum salaries attributed to professions in function of their prestige in society. Results showed: 1--the relationship between the estimation of magnitudes and the estimation of the number of minimum salaries attributed to the professions in function of their prestige is characterized by a function of potence with an exponent lower than 1,0,2--the orders of degrees of prestige of the professions resultant from different experiments involving different samples of subjects are highly concordant (W = 0.85; p salaries).

  11. $L^{p}$-square function estimates on spaces of homogeneous type and on uniformly rectifiable sets

    CERN Document Server

    Hofmann, Steve; Mitrea, Marius; Morris, Andrew J

    2017-01-01

    The authors establish square function estimates for integral operators on uniformly rectifiable sets by proving a local T(b) theorem and applying it to show that such estimates are stable under the so-called big pieces functor. More generally, they consider integral operators associated with Ahlfors-David regular sets of arbitrary codimension in ambient quasi-metric spaces. The local T(b) theorem is then used to establish an inductive scheme in which square function estimates on so-called big pieces of an Ahlfors-David regular set are proved to be sufficient for square function estimates to hold on the entire set. Extrapolation results for L^p and Hardy space versions of these estimates are also established. Moreover, the authors prove square function estimates for integral operators associated with variable coefficient kernels, including the Schwartz kernels of pseudodifferential operators acting between vector bundles on subdomains with uniformly rectifiable boundaries on manifolds.

  12. Executive Function, Survival, and Hospitalization in Chronic Obstructive Pulmonary Disease. A Longitudinal Analysis of the National Emphysema Treatment Trial (NETT).

    Science.gov (United States)

    Dodd, James W; Novotny, Paul; Sciurba, Frank C; Benzo, Roberto P

    2015-10-01

    Cognitive dysfunction has been demonstrated in chronic obstructive pulmonary disease (COPD), but studies are limited to cross-sectional analyses or incompletely characterized populations. We examined longitudinal changes in sensitive measures of executive function in a well-characterized population of patients with severe COPD. This study was performed on patients enrolled in the National Emphysema Treatment Trial. To assess executive function, we analyzed trail making (TM) A and B times at enrollment in the trial (2,128 patients), and at 12 (731 patients) and 24 months (593 patients) after enrollment, adjusted for surgery, marriage status, age, education, income, depression, PaO2, PaCO2, and smoking. Associations with survival and hospitalizations were examined using Cox regression and linear regression models. The average age of the patients was 66.4 years, and the average FEV1 was 23.9% predicted. At the time of enrolment, 38% had executive dysfunction. Compared with those who did not, these patients were older, less educated, had higher oxygen use, higher PaCO2, worse quality of life as measured by the St. George's Respiratory Quotient, reduced well-being, and lower social function. There was no significant change over 2 years in TM A or B times after adjustment for covariables. Changes in TM B times were modestly associated with survival, but changes in TM B-A times were not. Changes in TM scores were not associated with frequency of hospitalization. Lung function, PaO2, smoking, survival, and hospitalizations were not significantly different in those with executive dysfunction. In this large population of patients with severe emphysema and heavy cigarette smoking exposure, there was no significant decline over 2 years in cognitive executive function as measured by TM tests. There was no association between executive function impairment and frequency of hospitalization, and there was a possible modest association with survival. It is plausible that

  13. Growth and annual survival estimates to examine the ecology of larval lamprey and the implications of ageing error in fitting models.

    Science.gov (United States)

    Schultz, L D; Chasco, B E; Whitlock, S L; Meeuwig, M H; Schreck, C B

    2017-04-01

    This study used existing western brook lamprey Lampetra richardsoni age information to fit three different growth models (i.e. von Bertalanffy, Gompertz and logistic) with and without error in age estimates. Among these growth models, there was greater support for the logistic and Gompertz models than the von Bertalanffy model, regardless of ageing error assumptions. The von Bertalanffy model, however, appeared to fit the data well enough to permit survival estimates; using length-based estimators, annual survival varied between 0·64 (95% credibility interval: 0·44-0·79) and 0·81 (0·79-0·83) depending on ageing and growth process error structure. These estimates are applicable to conservation and management of L. richardsoni and other western lampreys (e.g. Pacific lamprey Entosphenus tridentatus) and can potentially be used in the development of life-cycle models for these species. These results also suggest that estimators derived from von Bertalanffy growth models should be interpreted with caution if there is high uncertainty in age estimates. © 2016 The Fisheries Society of the British Isles.

  14. Always follow your nose: the functional significance of social chemosignals in human reproduction and survival.

    Science.gov (United States)

    Lübke, Katrin T; Pause, Bettina M

    2015-02-01

    This article is part of a Special Issue "Chemosignals and Reproduction" Across phyla, chemosensory communication is crucial for mediating a variety of social behaviors, which form the basis for ontogenetic and phylogenetic survival. In the present paper, evidence on chemosensory communication in humans, with special reference to reproduction and survival, will be presented. First, the impact of chemosignals on human reproduction will be reviewed. Work will be presented, showing how chemosensory signals are involved in mate choice and partnership formation by communicating attractiveness and facilitating a partner selection, which is of evolutionary advantage, and furthermore providing information about the level of sexual hormones. In addition to direct effects on phylogenetic survival, chemosignals indirectly aid reproductive success by fostering harm protection. Results will be presented, showing that chemosensory communication aids the emotional bond between mother and child, which in turn motivates parental caretaking and protection, leading to infant survival. Moreover, the likelihood of group survival can be increased through the use of stress-related chemosignals. Stress-related chemosignals induce a stress-related physiology in the perceiver, thereby priming a fight-flight-response, which is necessary for an optimum adaption to environmental harm. Finally, effects of sexual orientation on chemosensory communication will be discussed in terms of their putative role in stabilizing social groups, which might indirectly provide harm protection and foster survival. An integrative model of the presented data will be introduced. In conclusion, an outlook, focusing on the involvement of chemosensory communication in human social behavior and illustrating a novel approach to the significance of chemosensory signals in human survival, will be given. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. INCREASING OF PRECISE ESTIMATION OF OPTIMAL CRITERIA BOILER FUNCTIONING

    Directory of Open Access Journals (Sweden)

    Y. M. Skakovsk

    2016-08-01

    Full Text Available Results of laboratory and industrial research allowed offering a way to improve the accuracy of estimation the optimal criterion of boilers' operation depending on fuel quality. Criterion is calculated continuously during boiler operation as heat ratio transmitted in production with superheated steam to the thermal energy obtained by combustion in boiler’s furnace fuel (natural gas .The non-linearity dependence of steam enthalpy from its temperature and pressure are considered when calculating, as well as changes in calorific value of natural gas, depending on variety in nitrogen content therein. The control algorithm and program for Ukrainian PLC MIC-52 are offered. The user selection program implements two searching modes for criterion maximum: automated and automatic. The results are going to be used for upgrading the existing control system on sugar factory.

  16. Nonparametric estimation of the derivative of the regression function: application to sea shores water quality

    OpenAIRE

    Bercu, Bernard; Capderou, Sami; Durrieu, Gilles

    2016-01-01

    This paper is devoted to the nonparametric estimation of the derivative of the regression function in a nonparametric regression model. We implement a very efficient and easy to handle statistical procedure based on the derivative of the recursive Nadaraya-Watson estimator. We establish the almost sure convergence as well as the asymptotic normality for our estimates. We also illustrate our nonparametric estimation procedure on simulated and real life data associated with sea shores water qua...

  17. Abbreviated care-process quality indicator sets linked with survival and functional status benefit in older adults under ambulatory care.

    Science.gov (United States)

    Min, Lillian; Reuben, David; Karlamangla, Arun; Naeim, Arash; Prenovost, Katherine; Lee, Pearl; Wenger, Neil

    2014-08-01

    To identify subsets of ambulatory care (outpatient only) quality indicators (QIs) associated with better survival and physical function outcomes. Observational cohort study. Pooled data from the Assessing Care of Vulnerable Elders (ACOVE)-1 study, which measured quality of care using 140 care-process QIs, and the subsequent ACOVE-2 study, which reduced the QIs to 69 ambulatory care QIs. Older adults receiving ambulatory care (N=1,015). To prioritize and reduce the QIs into subsets, an expert panel rated each of 69 ambulatory care QIs for the strength of the link between process and benefit, defined as direct trial evidence on older adults or high expectation of benefit if a trial were conducted in older adults. This resulted in three reduced QI sets, reflecting their intended benefit: 17 QIs for survival (ACOVE Quality for Survival (AQS)-17), five QIs to preserve function (AQF-5), and 16 QIs to improve quality-of-life related to physical health and symptoms (AQQ-16). Whether AQS-17 would predict 3-year survival was first tested in 1,015 pooled ACOVE-1 and ACOVE-2 participants. Second, whether AQF-5 (n=74) and AQQ-16 (n=359) would predict change in the Physical Component Summary (PCS) score of the Medical Outcomes Study 12-item Short-Form Survey at 1 year was tested in the ACOVE-2 cohort. Control variables were age, function-based vulnerability, and comorbidity. Each 20-percentage-point increment in AQS-17 was associated with survival (hazard ratio (HR)=0.83, P=.01) up to 500 days but not thereafter. AQF-5, but not AQQ-16, predicted 1-year improvement in PCS score (1.13-points per 20%-point increment in AQF-5, P=.02). Subsets of care processes can be linked with outcomes important to older adults. The AQS-17 and AQF-5 are potential tools for improving ambulatory care of older adults. © 2014, Copyright the Authors Journal compilation © 2014, The American Geriatrics Society.

  18. Robust estimation of the expected survival probabilities from high-dimensional Cox models with biomarker-by-treatment interactions in randomized clinical trials

    Directory of Open Access Journals (Sweden)

    Nils Ternès

    2017-05-01

    Full Text Available Abstract Background Thanks to the advances in genomics and targeted treatments, more and more prediction models based on biomarkers are being developed to predict potential benefit from treatments in a randomized clinical trial. Despite the methodological framework for the development and validation of prediction models in a high-dimensional setting is getting more and more established, no clear guidance exists yet on how to estimate expected survival probabilities in a penalized model with biomarker-by-treatment interactions. Methods Based on a parsimonious biomarker selection in a penalized high-dimensional Cox model (lasso or adaptive lasso, we propose a unified framework to: estimate internally the predictive accuracy metrics of the developed model (using double cross-validation; estimate the individual survival probabilities at a given timepoint; construct confidence intervals thereof (analytical or bootstrap; and visualize them graphically (pointwise or smoothed with spline. We compared these strategies through a simulation study covering scenarios with or without biomarker effects. We applied the strategies to a large randomized phase III clinical trial that evaluated the effect of adding trastuzumab to chemotherapy in 1574 early breast cancer patients, for which the expression of 462 genes was measured. Results In our simulations, penalized regression models using the adaptive lasso estimated the survival probability of new patients with low bias and standard error; bootstrapped confidence intervals had empirical coverage probability close to the nominal level across very different scenarios. The double cross-validation performed on the training data set closely mimicked the predictive accuracy of the selected models in external validation data. We also propose a useful visual representation of the expected survival probabilities using splines. In the breast cancer trial, the adaptive lasso penalty selected a prediction model with 4

  19. Estimation of acoustic resonances for room transfer function equalization

    DEFF Research Database (Denmark)

    Gil-Cacho, Pepe; van Waterschoot, Toon; Moonen, Marc

    2010-01-01

    Strong acoustic resonances create long room impulse responses (RIRs) which may harm the speech transmission in an acoustic space and hence reduce speech intelligibility. Equalization is performed by cancelling the main acoustic resonances common to multiple room transfer functions (RTFs), i.......e., common-acoustical-poles, in the room. This paper discusses the utilization of different norms (i.e., 2-norm and 1-norm) and models (i.e., all-pole and pole-zero) for RTF modelling and then equalization. Acoustic resonances may be modelled by means of the poles of the RTF. In the literature, however...

  20. Hypothesis likelihood function estimation for synthetic aperture radar targets

    Science.gov (United States)

    Fister, Thomas; Garber, Frederick D.; Sawtelle, Steven C.; Withman, Raymond L.

    1993-10-01

    The work described in this paper focuses on recent progress in radar signal processing and target recognition techniques developed in support of WL/AARA target recognition programs. The goal of the program is to develop evaluation methodologies of hypotheses in a model- based framework. In this paper, we describe an hypothesis evaluation strategy that is predicated on a generalized likelihood function framework, and allows for incomplete or inaccurate descriptions of the observed unknown target. The target hypothesis evaluation procedure we have developed begins with a structural analysis by means of parametric modeling of the several radar scattering centers. The energy, location, dispersion, and shape of all measured target scattering centers are parametrized. The resulting structural description is used to represent each target and, subsequently, to evaluate the hypotheses of each of the targets in the candidate set.

  1. Self-Consistent Nonparametric Maximum Likelihood Estimator of the Bivariate Survivor Function.

    Science.gov (United States)

    Prentice, R L

    2014-09-01

    As usually formulated the nonparametric likelihood for the bivariate survivor function is over-parameterized, resulting in uniqueness problems for the corresponding nonparametric maximum likelihood estimator. Here the estimation problem is redefined to include parameters for marginal hazard rates, and for double failure hazard rates only at informative uncensored failure time grid points where there is pertinent empirical information. Double failure hazard rates at other grid points in the risk region are specified rather than estimated. With this approach the nonparametric maximum likelihood estimator is unique, and can be calculated using a two-step procedure. The first step involves setting aside all doubly censored observations that are interior to the risk region. The nonparametric maximum likelihood estimator from the remaining data turns out to be the Dabrowska (1988) estimator. The omitted doubly censored observations are included in the procedure in the second stage using self-consistency, resulting in a non-iterative nonpara-metric maximum likelihood estimator for the bivariate survivor function. Simulation evaluation and asymptotic distributional results are provided. Moderate sample size efficiency for the survivor function nonparametric maximum likelihood estimator is similar to that for the Dabrowska estimator as applied to the entire dataset, while some useful efficiency improvement arises for corresponding distribution function estimator, presumably due to the avoidance of negative mass assignments.

  2. Predicting Structure-Function Relations and Survival following Surgical and Bronchoscopic Lung Volume Reduction Treatment of Emphysema.

    Science.gov (United States)

    Mondoñedo, Jarred R; Suki, Béla

    2017-02-01

    Lung volume reduction surgery (LVRS) and bronchoscopic lung volume reduction (bLVR) are palliative treatments aimed at reducing hyperinflation in advanced emphysema. Previous work has evaluated functional improvements and survival advantage for these techniques, although their effects on the micromechanical environment in the lung have yet to be determined. Here, we introduce a computational model to simulate a force-based destruction of elastic networks representing emphysema progression, which we use to track the response to lung volume reduction via LVRS and bLVR. We find that (1) LVRS efficacy can be predicted based on pre-surgical network structure; (2) macroscopic functional improvements following bLVR are related to microscopic changes in mechanical force heterogeneity; and (3) both techniques improve aspects of survival and quality of life influenced by lung compliance, albeit while accelerating disease progression. Our model predictions yield unique insights into the microscopic origins underlying emphysema progression before and after lung volume reduction.

  3. A Field Evaluation of an External and Neutrally Buoyant Acoustic Transmitter for Juvenile Salmon: Implications for Estimating Hydroturbine Passage Survival

    Science.gov (United States)

    Brown, Richard S.; Deng, Z. Daniel; Cook, Katrina V.; Pflugrath, Brett D.; Li, Xinya; Fu, Tao; Martinez, Jayson J.; Li, Huidong; Trumbo, Bradly A.; Ahmann, Martin L.; Seaburg, Adam G.

    2013-01-01

    Turbine-passed fish are exposed to rapid decreases in pressure which can cause barotrauma. The presence of an implanted telemetry tag increases the likelihood of injury or death from exposure to pressure changes, thus potentially biasing studies evaluating survival of turbine-passed fish. Therefore, a neutrally buoyant externally attached tag was developed to eliminate this bias in turbine passage studies. This new tag was designed not to add excess mass in water or take up space in the coelom, having an effective tag burden of zero with the goal of reducing pressure related biases to turbine survival studies. To determine if this new tag affects fish performance or susceptibility to predation, it was evaluated in the field relative to internally implanted acoustic transmitters (JSATS; Juvenile Salmon Acoustic Telemetry System) used widely for survival studies of juvenile salmonids. Survival and travel time through the study reach was compared between fish with either tag type in an area of high predation in the Snake and Columbia rivers, Washington. An additional group of fish affixed with neutrally-buoyant dummy external tags were implanted with passive integrated transponder (PIT) tags and recovered further downstream to assess external tag retention and injury. There were no significant differences in survival to the first detection site, 12 river kilometers (rkm) downstream of release. Travel times were also similar between groups. Conversely, externally-tagged fish had reduced survival (or elevated tag loss) to the second detection site, 65 rkm downstream. In addition, the retention study revealed that tag loss was first observed in fish recaptured approximately 9 days after release. Results suggest that this new tag may be viable for short term (<8 days) single-dam turbine-passage studies and under these situations, may alleviate the turbine passage-related bias encountered when using internal tags, however further research is needed to confirm this. PMID

  4. A field evaluation of an external and neutrally buoyant acoustic transmitter for juvenile salmon: implications for estimating hydroturbine passage survival.

    Directory of Open Access Journals (Sweden)

    Richard S Brown

    Full Text Available Turbine-passed fish are exposed to rapid decreases in pressure which can cause barotrauma. The presence of an implanted telemetry tag increases the likelihood of injury or death from exposure to pressure changes, thus potentially biasing studies evaluating survival of turbine-passed fish. Therefore, a neutrally buoyant externally attached tag was developed to eliminate this bias in turbine passage studies. This new tag was designed not to add excess mass in water or take up space in the coelom, having an effective tag burden of zero with the goal of reducing pressure related biases to turbine survival studies. To determine if this new tag affects fish performance or susceptibility to predation, it was evaluated in the field relative to internally implanted acoustic transmitters (JSATS; Juvenile Salmon Acoustic Telemetry System used widely for survival studies of juvenile salmonids. Survival and travel time through the study reach was compared between fish with either tag type in an area of high predation in the Snake and Columbia rivers, Washington. An additional group of fish affixed with neutrally-buoyant dummy external tags were implanted with passive integrated transponder (PIT tags and recovered further downstream to assess external tag retention and injury. There were no significant differences in survival to the first detection site, 12 river kilometers (rkm downstream of release. Travel times were also similar between groups. Conversely, externally-tagged fish had reduced survival (or elevated tag loss to the second detection site, 65 rkm downstream. In addition, the retention study revealed that tag loss was first observed in fish recaptured approximately 9 days after release. Results suggest that this new tag may be viable for short term (<8 days single-dam turbine-passage studies and under these situations, may alleviate the turbine passage-related bias encountered when using internal tags, however further research is needed to

  5. Off-Grid DOA Estimation Based on Analysis of the Convexity of Maximum Likelihood Function

    Science.gov (United States)

    LIU, Liang; WEI, Ping; LIAO, Hong Shu

    Spatial compressive sensing (SCS) has recently been applied to direction-of-arrival (DOA) estimation owing to advantages over conventional ones. However the performance of compressive sensing (CS)-based estimation methods decreases when true DOAs are not exactly on the discretized sampling grid. We solve the off-grid DOA estimation problem using the deterministic maximum likelihood (DML) estimation method. In this work, we analyze the convexity of the DML function in the vicinity of the global solution. Especially under the condition of large array, we search for an approximately convex range around the ture DOAs to guarantee the DML function convex. Based on the convexity of the DML function, we propose a computationally efficient algorithm framework for off-grid DOA estimation. Numerical experiments show that the rough convex range accords well with the exact convex range of the DML function with large array and demonstrate the superior performance of the proposed methods in terms of accuracy, robustness and speed.

  6. Survival Patterns of 5750 Stereotactic Radiosurgery-Treated Patients with Brain Metastasis as a Function of the Number of Lesions.

    Science.gov (United States)

    Ali, Mir Amaan; Hirshman, Brian R; Wilson, Bayard; Carroll, Kate T; Proudfoot, James A; Goetsch, Steven J; Alksne, John F; Ott, Kenneth; Aiyama, Hitoshi; Nagano, Osamu; Carter, Bob S; Fogarty, Gerald; Hong, Angela; Serizawa, Toru; Yamamoto, Masaaki; Chen, Clark C

    2017-11-01

    The number of brain metastases (BMs) plays an important role in the decision between stereotactic radiosurgery (SRS) and whole-brain radiation therapy. We analyzed the survival of 5750 SRS-treated patients with BM as a function of BM number. Survival analyses were performed with Kaplan-Meier analysis as well as univariate and multivariate Cox proportional hazards models. Patients with BMs were first categorized as those with 1, 2-4, and 5-10 BMs based on the scheme proposed by Yamamoto et al. (Lancet Oncology 2014). Median overall survival for patients with 1 BM was superior to those with 2-4 BMs (7.1 months vs. 6.4 months, P = 0.009), and survival of patients with 2-4 BMs did not differ from those with 5-10 BMs (6.4 months vs. 6.3 months, P = 0.170). The median survival of patients with >10 BMs was lower than those with 2-10 BMs (6.3 months vs. 5.5 months, P = 0.025). In a multivariate model that accounted for age, Karnofsky Performance Score, systemic disease status, tumor histology, and cumulative intracranial tumor volume, we observed a ∼10% increase in hazard of death when comparing patients with 1 versus 2-10 BMs (P 10 BMs (P < 0.001). When BM number was modeled as a continuous variable rather than using the classification by Yamamoto et al., we observed a step-wise 4% increase in the hazard of death for every increment of 6-7 BM (P < 0.001). The contribution of BM number to overall survival is modest and should be considered as one of the many variables considered in the decision between SRS and whole-brain radiation therapy. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Lactobacillus plantarum-survival, functional and potential probiotic properties in the human intestinal tract

    NARCIS (Netherlands)

    Vries, de M.C.; Vaughan, E.E.; Kleerebezem, M.; Vos, de W.M.

    2006-01-01

    Lactobacillus plantarum is a versatile lactic acid bacterium that is encountered in a range of environmental niches, has a proven ability to survive gastric transit, and can colonize the intestinal tract of human and other mammals. Several studies describe the effects of L. plantarum consumption on

  8. Improved survival prediction from lung function data in a large population sample

    DEFF Research Database (Denmark)

    Miller, M.R.; Pedersen, O.F.; Lange, P.

    2008-01-01

    . In univariate predictions of all cause mortality the HR for FEV1/ht(2) categories was 2-4 times higher than those for FEV1PP and 3-10 times higher for airway related tung disease mortality. We conclude that FEV1/ht(2) is superior to FEV1PP for predicting survival. in a general population and this method...

  9. Cálculo de la supervivencia relativa: Comparación de métodos de estimación de la supervivencia esperada Relative survival computation: Comparison of methods for estimating expected survival

    Directory of Open Access Journals (Sweden)

    Ramón Clèries

    2006-08-01

    Full Text Available El método más utilizado en el cálculo de la supervivencia de los pacientes diagnosticados de cáncer es la supervivencia relativa. Este método tiene en cuenta la estimación de la supervivencia esperada de dichos pacientes a partir de la mortalidad observada en la zona geográfica de la que proceden. Los métodos utilizados con mayor frecuencia en dicha estimación son los de Ederer (I y II y el método de Hakulinen. Para dichos cálculos es necesaria la disponibilidad de las tablas de supervivencia estratificadas por edad y por período de calendario. En este trabajo se presenta un ejemplo en el que se muestra cómo realizar dichos cálculos de tal forma que permitan al investigador decidir qué método es el más adecuado según el tipo de análisis que lleve a cabo. Se mostrará que, si el tiempo de seguimiento de la cohorte es inferior a 10 años, cualquiera de los métodos debería dar resultados similares. Sin embargo, el método recomendable es el de Hakulinen, ya que tiene en cuenta la heterogeneidad en el momento de las censuras debidas a posibles pérdidas de seguimiento o abandonos.Relative survival is the most commonly used method to determine survival in patients diagnosed with cancer. This method takes into account estimation of expected survival in cancer patients based on the observed mortality in the geographical area to which they belong. The most frequently used methods for estimation of expected survival are the Ederer (I and II and Hakulinen methods. Survival tables for the geographical areas stratified by age and calendar year are required for these calculations. The present article presents an example of how to perform these estimations and how to choose the most appropriate method for the type of analysis to be performed. This article shows that if the follow-up of the cohort is less than 10 years, any of these methods should give similar results. However, the Hakulinen method is preferred, since it accounts for

  10. Estimation of magnesium in patients with functional hypoparathyroidism

    Directory of Open Access Journals (Sweden)

    Subramanian Kannan

    2014-01-01

    Full Text Available Context: It is evident that about 30-50% of patients with Vitamin D deficiency (VDD do not manifest develop secondary hyperparathyroidism (SHPT. A number of theories have been proposed to explain this lack of SHPT, including hypomagnesemia. Settings and Design: Retrospective review of laboratory database. Materials and Methods: We evaluated the differences in serum magnesium (Mg levels among those with VDD with or without SHPT. A retrospective review of 6255 laboratory data of bone mineral profiles performed in the period of 2007-2013. After excluding patients with hypercalcemia, renal dysfunction/unknown kidney function and primary hypothyroidism, the remaining 1323 patient data were analyzed. SHPT was defined as serum parathyroid hormone >65 in those with VDD. Statistical Analysis Used: ANOVA and Wilcoxon tests as appropriate to compare means. Multivariate logistic regression to analyze relation between variables and outcome of SHPT. Results: We noted that 55% patients (n = 727 had VDD, and among those who had VDD, 23% (n = 170 were hypocalcemic (corrected serum calcium <8.5. Patients with VDD who did not exhibit SHPT were 56% (n = 407. The mean (±standard deviation serum Mg levels in the entire cohort (n = 1323 was 1.94 ± 0.26 mg/dl and 1.95 ± 0.26 mg/dl in VDD cohort and 2 ± 0.31 mg/dl in the VDD-hypocalcemic cohort. There was no statistical difference in the Mg levels among those with SHPT compared to those without SHPT (P = 0.14. Serum calcium and phosphorus were lower in those with SHPT (P = 0.06 and P < 0.001, respectively. In multivariate logistic regression, serum calcium (P = 0.043, phosphorus (P < 0.001 and severe VDD (P < 0.001 independently correlated with occurrence of SHPT in VDD. Conclusions: Serum Mg levels did not explain the functional hypoparathyroidism seen in about half of the patients with VDD. A low normal serum calcium and phosphorus levels are more likely to be associated with VDD patients who develop SHPT.

  11. 10-Day survival of Hyalella azteca as a function of water quality parameters.

    Science.gov (United States)

    Javidmehr, Alireza; Kass, Philip H; Deanovic, Linda A; Connon, Richard E; Werner, Inge

    2015-05-01

    Estuarine systems are among the most impacted ecosystems due to anthropogenic contaminants; however, they present unique challenges to toxicity testing with regard to varying water quality parameters. The euryhaline amphipod species, Hyalella azteca, is widely used in toxicity testing and well suited for testing estuarine water samples. Nevertheless, the influence of relevant water quality parameters on test endpoints must be quantified in order to efficiently use this species for routine monitoring. Here, we studied the influence of five water quality parameters: electrical conductivity, pH, un-ionized ammonia, dissolved oxygen and temperature, on H. azteca survival in a water column toxicity test. A model was developed to quantify and predict the independent and interacting effects of water quality variables on 10-day survival. The model allows simultaneous assessment of multiple potential predictors recorded during the tests. Data used for modeling came from 1089 tests performed on ambient water samples over a period of three years (2006-2008). The final model reflects significant effects of predictors and their two-way interactions. The effect of each level of all predictors on survival probability of H. azteca was examined by comparing levels of each predictor at a time, while holding all others at their lowest (reference) level. This study showed that predictors of survival in water column tests should not be evaluated in isolation in the interpretation of H. azteca water column tests. Our model provides a useful tool to predict expected control survival based on relevant water quality parameters, and thus enables the use of H. azteca tests for toxicity monitoring in estuaries with a wide range of water quality conditions. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Estimating the stability of Escherichia coli O157:H7 survival in manure-amended soils with different management histories

    NARCIS (Netherlands)

    Semenov, A.V.; Franz, E.; Overbeek, van L.S.; Termorshuizen, A.J.; Bruggen, van A.H.C.

    2008-01-01

    The objective of this study is to describe survival of Escherichia coli O157:H7 populations in manure-amended soils in terms of population stability, i.e. the temporal variation around the decline curve, in relation to soil characteristics indicative of soil health. Cow manure inoculated with E.

  13. Estimating accounting prices for common pool natural resources: A distance function approach

    Science.gov (United States)

    Koundouri, Phoebe; Xepapadeas, Anastasios

    2004-06-01

    We extend existing methodology for estimating shadow prices for exhaustible natural resources to renewable resources with common pool characteristics, using groundwater in irrigated agriculture as an example. The resource's shadow price is defined in terms of a perfect foresight open loop Nash equilibrium. Furthermore, we introduce a new estimation approach and derive shadow groundwater scarcity rents by estimating a stochastic restricted distance function using duality results between distance and cost functions. This approach is appropriate when price information is not available or when cost, profit, or revenue functions representations are precluded because of violations of the required behavior assumptions. We use our results to study policy implications for groundwater management.

  14. Using zero-norm constraint for sparse probability density function estimation

    Science.gov (United States)

    Hong, X.; Chen, S.; Harris, C. J.

    2012-11-01

    A new sparse kernel probability density function (pdf) estimator based on zero-norm constraint is constructed using the classical Parzen window (PW) estimate as the target function. The so-called zero-norm of the parameters is used in order to achieve enhanced model sparsity, and it is suggested to minimize an approximate function of the zero-norm. It is shown that under certain condition, the kernel weights of the proposed pdf estimator based on the zero-norm approximation can be updated using the multiplicative nonnegative quadratic programming algorithm. Numerical examples are employed to demonstrate the efficacy of the proposed approach.

  15. Survival Estimates and Mortality Risk Factors in a Cohort of HIV Vertically Infected Individuals in Salvador, Brazil.

    Science.gov (United States)

    Lorenzo, Cynthia R S; Netto, Eduardo M; Patrício, Fátima R L; Brites, Carlos

    2017-03-01

    There are few data on long-term survival of Brazilian children with vertically acquired HIV infection. We assessed survival, mortality risk factors and response to antiretroviral therapy (ART). We compared children with early and late access to care. We used Kaplan-Meier survival curves with Log-rank tests to compare survival time and mortality rates of 245 HIV vertically infected children admitted for care during 2002-2014. Total follow-up sum was 1584.4 person-years. Overall survival was 83.9%. Median age at start of ART was 51.6 (18.0-94.2) months, and median age at death was 8.2 (1.7-10.1) years (mortality rate: 1.7/100 person-years). Pneumonia and sepsis were the main causes of death. Male gender, viral load (VL) ≥100,000 copies, severe immunosuppression, moderate/severe symptoms and history of opportunistic infection were associated with higher mortality in bivariate analysis. Only severe symptoms remained associated in multivariate analysis (P = 0.03). There was no difference in mortality in early compared to late access group. Overall, 217 patients received ART; 192 had a recent VL, of which 116 (59.8%) had ≤400 copies. Variables associated with therapeutic failure were as follows: VL ≥100,000 copies, less immune suppression, age <12 months at admission and age <3 years at ART start. We have a high mortality rate in comparison with developed countries. Although early access did not impact mortality, we detected a trend in favor of early treatment as a protecting factor against mortality. We need to increase adherence to care and treatment, and better drugs to optimize outcomes.

  16. Survival and growth of tree seedlings as a function of seed size in a gallery forest under restoration

    Directory of Open Access Journals (Sweden)

    Leonardo Gallo Macera

    2017-09-01

    Full Text Available ABSTRACT Seed size is commonly related to higher rates of emergence and survival, and biomass of seedlings when introduced by direct seeding. However, few studies have evaluated whether this relationship persists when species are reintroduced as seedlings or if this effect persists after seed reserves decline. This study evaluated the effect of seed size (mass on the probability of survival and growth of seedlings of nine native tree species introduced into a pasture area, which was originally a gallery forest in the state of São Paulo in Southeastern Brazil. The experiment occurred over the course of 24 months, in which was divided into three separate time intervals: 14 to 61 days, 61 days to 12 months, and 12 to 24 months. Seedling survival in the field was high for all three time-intervals. Seed mass positively influenced the probability of seedling survival throughout all three time-intervals after planting, but the intensity of this effect decreased with time. Species with smaller seeds exhibited higher relative growth rates (height, but only until the end of the first year. Our results suggest that seed mass is a functional trait that can predict the probability of the establishment of individual trees during forest restoration.

  17. No Detectable Trade-Offs Among Immune Function, Fecundity, and Survival via a Juvenile Hormone Analog in the House Cricket.

    Science.gov (United States)

    Nava-Sánchez, A; Munguía-Steyer, R; Córdoba-Aguilar, A

    2014-08-01

    Hormones are key regulators of resource allocation among functions and thus play an important role in resource-based trade-offs. The juvenile hormone (JH) is an insect hormone that mediates resource allocation between immunity and life history components. Here, we have tested whether this is the case using the house cricket. We investigated whether increased levels of JH (using methoprene, a JH analog) enable an enhanced survival and fecundity (via egg number) at the cost of reduced hemocyte number (a trait that is associated with immune response in insects) in the house cricket, Acheta domesticus L. We had three groups of adult crickets of both sexes: experimental (methoprene and acetone), positive control (methoprene), and negative control (no manipulation). Prior to and after experimental treatments, we counted the number of hemocytes (for the case of both sexes) and recorded the number of eggs laid and survival of females after the manipulation. There was no difference in hemocyte number, egg number, and survival. These results do not support a JH-mediated trade-off among immune ability, survival, and fecundity. We provide arguments to explain the lack of JH-mediated trade-offs in the house cricket.

  18. Survival-variation within and between functional categories of the African multimammate rat

    DEFF Research Database (Denmark)

    Julliard, Romain; Leirs, Herwig; Stenseth, Nils Chr.

    1999-01-01

    size, theoretical models assuming differential sensitivities of population growth rate or fitness to demographic parameters have mostly been untested, particularly against data on small mammals. 2, Statistical modelling capture-mark-recapture data on the multimammate rat (Mastomys natalensis) from...... of the multimammate rat. Whereas environmental factors in this population seem to affect survival rates of all individuals in a similar manner, density-dependent relationships are more complex. 4, The patterns of survival variation in small mammals may be different from those observed in large mammals. 5, Further...... studies of demography in small mammals should aim at understanding how much of the variability in population growth rate is accounted for by the variability of the demographic rates resulting from limiting (density-independent) and regulating (density-dependent) factors, respectively. This study...

  19. Lymphatic endothelial S1P promotes mitochondrial function and survival in naive T cells.

    Science.gov (United States)

    Mendoza, Alejandra; Fang, Victoria; Chen, Cynthia; Serasinghe, Madhavika; Verma, Akanksha; Muller, James; Chaluvadi, V Sai; Dustin, Michael L; Hla, Timothy; Elemento, Olivier; Chipuk, Jerry E; Schwab, Susan R

    2017-06-01

    Effective adaptive immune responses require a large repertoire of naive T cells that migrate throughout the body, rapidly identifying almost any foreign peptide. Because the production of T cells declines with age, naive T cells must be long-lived. However, it remains unclear how naive T cells survive for years while constantly travelling. The chemoattractant sphingosine 1-phosphate (S1P) guides T cell circulation among secondary lymphoid organs, including spleen, lymph nodes and Peyer's patches, where T cells search for antigens. The concentration of S1P is higher in circulatory fluids than in lymphoid organs, and the S1P1 receptor (S1P1R) directs the exit of T cells from the spleen into blood, and from lymph nodes and Peyer's patches into lymph. Here we show that S1P is essential not only for the circulation of naive T cells, but also for their survival. Using transgenic mouse models, we demonstrate that lymphatic endothelial cells support the survival of T cells by secreting S1P via the transporter SPNS2, that this S1P signals through S1P1R on T cells, and that the requirement for S1P1R is independent of the established role of the receptor in guiding exit from lymph nodes. S1P signalling maintains the mitochondrial content of naive T cells, providing cells with the energy to continue their constant migration. The S1P signalling pathway is being targeted therapeutically to inhibit autoreactive T cell trafficking, and these findings suggest that it may be possible simultaneously to target autoreactive or malignant cell survival.

  20. An estimating function approach to inference for inhomogeneous Neyman-Scott processes

    DEFF Research Database (Denmark)

    Waagepetersen, Rasmus

    2007-01-01

    This article is concerned with inference for a certain class of inhomogeneous Neyman-Scott point processes depending on spatial covariates. Regression parameter estimates obtained from a simple estimating function are shown to be asymptotically normal when the "mother" intensity for the Neyman-Sc...

  1. A new production function estimate of the euro area output gap

    NARCIS (Netherlands)

    Lemoine, M.; Mazzi, G.L.; Monperrus-Veroni, P.; Reynes, F.G.D.

    2010-01-01

    We develop a new version of the production function (PF) approach for estimating the output gap of the euro area. Assuming a CES (constant elasticity of substitution) technology, our model does not call for any (often imprecise) measure of the capital stock and improves the estimation of the trend

  2. Estimates of solutions for parabolic differential and difference functional equations and applications

    Directory of Open Access Journals (Sweden)

    Lucjan Sapa

    2012-01-01

    Full Text Available The theorems on the estimates of solutions for nonlinear second-order partial differential functional equations of parabolic type with Dirichlet's condition and for suitable implicit finite difference functional schemes are proved. The proofs are based on the comparison technique. The convergent and stable difference method is considered without the assumption of the global generalized Perron condition posed on the functional variable but with the local one only. It is a consequence of our estimates theorems. In particular, these results cover quasi-linear equations. However, such equations are also treated separately. The functional dependence is of the Volterra type.

  3. Online Estimation and Adaptive Control for a Class of History Dependent Functional Differential Equations

    OpenAIRE

    Dadashi, Shirin; Bobade, Parag; Kurdila, Andrew

    2017-01-01

    This paper presents sufficient conditions for the convergence of online estimation methods and the stability of adaptive control strategies for a class of history dependent, functional differential equations. The study is motivated by the increasing interest in estimation and control techniques for robotic systems whose governing equations include history dependent nonlinearities. The functional differential equations in this paper are constructed using integral operators that depend on distr...

  4. Integrins (alpha7beta1) in muscle function and survival. Disrupted expression in merosin-deficient congenital muscular dystrophy

    DEFF Research Database (Denmark)

    Vachon, P H; Xu, H; Liu, L

    1997-01-01

    Mutations in genes coding for dystrophin, for alpha, beta, gamma, and delta-sarcoglycans, or for the alpha2 chain of the basement membrane component merosin (laminin-2/4) cause various forms of muscular dystrophy. Analyses of integrins showed an abnormal expression and localization of alpha7beta1...... isoforms in myofibers of merosin-deficient human patients and mice, but not in dystrophin-deficient or sarcoglycan-deficient humans and animals. It was shown previously that skeletal muscle fibers require merosin for survival and function (Vachon, P.H., F. Loechel, H. Xu, U.M. Wewer, and E. Engvall. 1996...... in skeletal muscle; (b) indicate a merosin dependence for the accurate expression and membrane localization of alpha7beta1D integrins in myofibers; (c) provide a molecular basis for the critical role of merosin in myofiber survival; and (d) add new insights to the pathogenesis of neuromuscular disorders....

  5. Data and analyses of woody restoration planting survival and growth as a function of wild ungulate herbivory

    Directory of Open Access Journals (Sweden)

    Joshua P. Averett

    2017-10-01

    Full Text Available These data and analyses support the research article “Wild ungulate herbivory suppresses deciduous woody plant establishment following salmonid stream restoration” Averett et al. (2017 [1]. The data and analyses presented here include: (1 planting density, survival and growth (two years post restoration of riparian plantings along an ~11 km stream reach in northeastern Oregon as a function of herbivory treatment (protected/not protected from wild ungulate herbivory, habitat type, and planting species; and (2 abundance and height distributions of naturally occurring deciduous woody species along the restored stream reach two years post restoration. Survival and growth analyses are provided as output from multiple logistic and mixed effect regression models respectively.

  6. Functional level at admission is a predictor of survival in older patients admitted to an acute geriatric unit

    DEFF Research Database (Denmark)

    Matzen, Lars E; Jepsen, Ditte B; Ryg, Jesper

    2012-01-01

    ABSTRACT: BACKGROUND: Functional decline is associated with increased risk of mortality in geriatric patients.Assessment of activities of daily living (ADL) with the Barthel Index (BI) at admission wasstudied as a predictor of survival in older patients admitted to an acute geriatric unit. METHODS......: All first admissions of patients with age >65 years between January 1st 2005 and December31st 2009 were included. Data on BI, sex, age, and discharge diagnoses were retrieved fromthe hospital patient administrative system, and data on survival until September 6th 2010 wereretrieved from the Civil...... Personal Registry. Co-morbidity was measured with Charlson ComorbidityIndex (CCI). Patients were followed until death or end of study. RESULTS: 5,087 patients were included, 1,852 (36.4%) men and 3,235 (63.6%) women with mean age(SD) 82.0 (6.8) and 84.0 (7.0) years respectively. The median [IQR] length...

  7. Surviving a brain tumor in childhood: impact on family functioning in adolescence

    NARCIS (Netherlands)

    Beek, Laura; Schappin, Renske; Gooskens, Rob; Huisman, Jaap; Jongmans, Marian

    2015-01-01

    OBJECTIVE: To investigate family functioning in families with an adolescent survivor of a pediatric brain tumor. We explored whether adolescent, parent, disease and treatment factors, and demographic characteristics predicted family functioning. METHODS: In this cross-sectional study, 45 adolescent

  8. Off-pump anteroapical aneurysm plication following left ventricular postinfarction aneurysm: effect on cardiac function, clinical status and survival.

    Science.gov (United States)

    Huang, Xin-sheng; Gu, Cheng-xiong; Yang, Jun-feng; Wei, Hua; Li, Jing-xing; Zhou, Qi-wen

    2013-04-01

    In patients with coronary disease and aneurysm, ventricular reconstruction with revascularization is a surgical option. Details of patient selection and optimal surgical technique are still debated. We report our results with off-pump aneurysm plication after ventricular aneurysm with relative wall thinning. We retrospectively reviewed the records of 248 patients who had an operation for postinfarction left ventricular aneurysm. Reconstruction was accomplished by off-pump anteroapical aneurysm plication. The following variables were recorded: preoperative clinical, angiographic and echocardiographic findings and operative procedures. Outcomes were early mortality, long-term survival and poor 5-year result, defined as the need for transplantation or repeated hospitalization for congestive heart failure. Risk factors were pinpointed using the t test and survival curves. Independent risk factors were identified using Cox regression methods. Hospital mortality was low (2.0%). Mean follow-up was 5.8 (standard deviation [SD] 3.8) years. Actuarial survival at 1 and 5 years was 94% and 84%. Among the 232 survivors, 200 were in functional class I or II, and the average increase in ejection fraction was 14.0% (SD 3.1%). As determined by multivariable analysis, factors predicting poor outcome were advanced age, ejection fraction less than 0.35, conicity index less than 1, end-systolic volume index greater than 80 mL/m2, advanced New York Heart Association functional class and congestive heart failure. Using wall thinning as a criterion for patient selection, the technique of off-pump anteroapical aneurysm plication can be performed with low operative mortality and provides good symptomatic relief and long-term survival.

  9. Hepatocyte nuclear factor 4A improves hepatic differentiation of immortalized adult human hepatocytes and improves liver function and survival.

    Science.gov (United States)

    Hang, Hua-Lian; Liu, Xin-Yu; Wang, Hai-Tian; Xu, Ning; Bian, Jian-Min; Zhang, Jian-Jun; Xia, Lei; Xia, Qiang

    2017-11-15

    Immortalized human hepatocytes (IHH) could provide an unlimited supply of hepatocytes, but insufficient differentiation and phenotypic instability restrict their clinical application. This study aimed to determine the role of hepatocyte nuclear factor 4A (HNF4A) in hepatic differentiation of IHH, and whether encapsulation of IHH overexpressing HNF4A could improve liver function and survival in rats with acute liver failure (ALF). Primary human hepatocytes were transduced with lentivirus-mediated catalytic subunit of human telomerase reverse transcriptase (hTERT) to establish IHH. Cells were analyzed for telomerase activity, proliferative capacity, hepatocyte markers, and tumorigenicity (c-myc) expression. Hepatocyte markers, hepatocellular functions, and morphology were studied in the HNF4A-overexpressing IHH. Hepatocyte markers and karyotype analysis were completed in the primary hepatocytes using shRNA knockdown of HNF4A. Nuclear translocation of β-catenin was assessed. Rat models of ALF were treated with encapsulated IHH or HNF4A-overexpressing IHH. A HNF4A-positive IHH line was established, which was non-tumorigenic and conserved properties of primary hepatocytes. HNF4A overexpression significantly enhanced mRNA levels of genes related to hepatic differentiation in IHH. Urea levels were increased by the overexpression of HNF4A, as measured 24h after ammonium chloride addition, similar to that of primary hepatocytes. Chromosomal abnormalities were observed in primary hepatocytes transfected with HNF4A shRNA. HNF4α overexpression could significantly promote β-catenin activation. Transplantation of HNF4A overexpressing IHH resulted in better liver function and survival of rats with ALF compared with IHH. HNF4A improved hepatic differentiation of IHH. Transplantation of HNF4A-overexpressing IHH could improve the liver function and survival in a rat model of ALF. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Prolonged Minocycline Treatment Impairs Motor Neuronal Survival and Glial Function in Organotypic Rat Spinal Cord Cultures

    Science.gov (United States)

    Pinkernelle, Josephine; Fansa, Hisham; Ebmeyer, Uwe; Keilhoff, Gerburg

    2013-01-01

    Background Minocycline, a second-generation tetracycline antibiotic, exhibits anti-inflammatory and neuroprotective effects in various experimental models of neurological diseases, such as stroke, Alzheimer’s disease, amyotrophic lateral sclerosis and spinal cord injury. However, conflicting results have prompted a debate regarding the beneficial effects of minocycline. Methods In this study, we analyzed minocycline treatment in organotypic spinal cord cultures of neonatal rats as a model of motor neuron survival and regeneration after injury. Minocycline was administered in 2 different concentrations (10 and 100 µM) at various time points in culture and fixed after 1 week. Results Prolonged minocycline administration decreased the survival of motor neurons in the organotypic cultures. This effect was strongly enhanced with higher concentrations of minocycline. High concentrations of minocycline reduced the number of DAPI-positive cell nuclei in organotypic cultures and simultaneously inhibited microglial activation. Astrocytes, which covered the surface of the control organotypic cultures, revealed a peripheral distribution after early minocycline treatment. Thus, we further analyzed the effects of 100 µM minocycline on the viability and migration ability of dispersed primary glial cell cultures. We found that minocycline reduced cell viability, delayed wound closure in a scratch migration assay and increased connexin 43 protein levels in these cultures. Conclusions The administration of high doses of minocycline was deleterious for motor neuron survival. In addition, it inhibited microglial activation and impaired glial viability and migration. These data suggest that especially high doses of minocycline might have undesired affects in treatment of spinal cord injury. Further experiments are required to determine the conditions for the safe clinical administration of minocycline in spinal cord injured patients. PMID:23967343

  11. Environmental enrichment extends photoreceptor survival and visual function in a mouse model of retinitis pigmentosa.

    Directory of Open Access Journals (Sweden)

    Ilaria Barone

    Full Text Available Slow, progressive rod degeneration followed by cone death leading to blindness is the pathological signature of all forms of human retinitis pigmentosa (RP. Therapeutic schemes based on intraocular delivery of neuroprotective agents prolong the lifetime of photoreceptors and have reached the stage of clinical trial. The success of these approaches depends upon optimization of chronic supply and appropriate combination of factors. Environmental enrichment (EE, a novel neuroprotective strategy based on enhanced motor, sensory and social stimulation, has already been shown to exert beneficial effects in animal models of various disorders of the CNS, including Alzheimer and Huntington disease. Here we report the results of prolonged exposure of rd10 mice, a mutant strain undergoing progressive photoreceptor degeneration mimicking human RP, to such an enriched environment from birth. By means of microscopy of retinal tissue, electrophysiological recordings, visual behaviour assessment and molecular analysis, we show that EE considerably preserves retinal morphology and physiology as well as visual perception over time in rd10 mutant mice. We find that protective effects of EE are accompanied by increased expression of retinal mRNAs for CNTF and mTOR, both factors known as instrumental to photoreceptor survival. Compared to other rescue approaches used in similar animal models, EE is highly effective, minimally invasive and results into a long-lasting retinal protection. These results open novel perspectives of research pointing to environmental strategies as useful tools to extend photoreceptor survival.

  12. Functional disruption of peroxiredoxin by bismuth antiulcer drugs attenuates Helicobacter pylori survival.

    Science.gov (United States)

    Chang, Yuen-Yan; Cheng, Tianfan; Yang, Xinming; Jin, Lijian; Sun, Hongzhe; Li, Hongyan

    2017-07-01

    Bismuth drugs have been used clinically to treat infections from Helicobacter pylori, a pathogen that is strongly related to gastrointestinal diseases even stomach cancer. Despite extensive studies, the mechanisms of action of bismuth drugs are not fully understood. Alkyl hydroperoxide reductase subunit C (AhpC) is the most abundant 2-cysteine peroxiredoxin, crucial for H. pylori survival in the host by defense of oxidative stress. Herein we show that a Bi(III) antiulcer drug (CBS) binds to the highly conserved cysteine residues (Cys49 and Cys169) with a dissociation constant (K d ) of Bi(III) to AhpC of 3.0 (±1.0) × 10 -24 M. Significantly the interaction of CBS with AhpC disrupts the peroxiredoxin and chaperone activities of the enzyme both in vitro and in bacterial cells, leading to attenuated bacterial survival. Moreover, using a home-made fluorescent probe, we demonstrate that Bi(III) also perturbs AhpC relocation between the cytoplasm and membrane region in decomposing the exogenous ROS. Our study suggests that disruption of redox homeostasis by bismuth drugs via interaction with key enzymes such as AhpC contributes to their antimicrobial activity.

  13. Hidden keys to survival: the type, density, pattern and functional role of emperor penguin body feathers.

    Science.gov (United States)

    Williams, Cassondra L; Hagelin, Julie C; Kooyman, Gerald L

    2015-10-22

    Antarctic penguins survive some of the harshest conditions on the planet. Emperor penguins breed on the sea ice where temperatures drop below -40°C and forage in -1.8°C waters. Their ability to maintain 38°C body temperature in these conditions is due in large part to their feathered coat. Penguins have been reported to have the highest contour feather density of any bird, and both filoplumes and plumules (downy feathers) are reported absent in penguins. In studies modelling the heat transfer properties and the potential biomimetic applications of penguin plumage design, the insulative properties of penguin plumage have been attributed to the single afterfeather attached to contour feathers. This attribution of the afterfeather as the sole insulation component has been repeated in subsequent studies. Our results demonstrate the presence of both plumules and filoplumes in the penguin body plumage. The downy plumules are four times denser than afterfeathers and play a key, previously overlooked role in penguin survival. Our study also does not support the report that emperor penguins have the highest contour feather density. © 2015 The Author(s).

  14. Significance of platelet and AFP levels and liver function parameters for HCC size and survival.

    Science.gov (United States)

    Carr, Brian I; Guerra, Vito; Giannini, Edoardo G; Farinati, Fabio; Ciccarese, Francesca; Rapaccini, Gian Ludovico; Di Marco, Maria; Benvegnù, Luisa; Zoli, Marco; Borzio, Franco; Caturelli, Eugenio; Chiaramonte, Maria; Trevisani, Franco

    2014-09-30

    Hepatocellular carcinoma (HCC) is a heterogeneous disease with both tumor and liver factors being involved. To investigate HCC clinical phenotypes and factors related to HCC size. Prospectively-collected HCC patients' data from a large Italian database were arranged according to the maximum tumor diameter (MTD) and divided into tumor size terciles, which were then compared in terms of several common clinical parameters and patients' survival. An higer MTD tercile was significantly associated with increased blood alpha-fetoprotein (AFP), gamma-glutamyl transpeptidase (GGTP), and platelet levels. Patients with higher platelet levels had larger tumors and higher GGTP levels, with lower bilirubin levels. However, patients with the highest AFP levels had larger tumors and higher bilirubin levels, reflecting an aggressive biology. AFP correlation analysis revealed the existence of 2 different groups of patients: those with higher and with lower AFP levels, each with different patient and tumor characteristics. The Cox proportional-hazard model showed that a higher risk of death was correlated with GGTP and bilirubin levels, tumor size and number, and portal vein thrombosis (PVT), but not with AFP or platelet levels. An increased tumor size was associated with increased blood platelet counts, AFP and GGTP levels. Platelet and AFP levels were important indicators of tumor size, but not of survival.

  15. Estimating survival of dental fillings on the basis of interval-censored data and multi-state models

    DEFF Research Database (Denmark)

    Joly, Pierre; Gerds, Thomas A; Qvist, Vibeke

    2012-01-01

    We aim to compare the life expectancy of a filling in a primary tooth between two types of treatments. We define the probabilities that a dental filling survives without complication until the permanent tooth erupts from beneath (exfoliation). We relate the time to exfoliation of the tooth...... with all these particularities, we propose to use a parametric four-state model with three random effects to take into account the hierarchical cluster structure. For inference, right and interval censoring as well as left truncation have to be dealt with. With the proposed approach, we can conclude...

  16. Application of independent component analysis for speech-music separation using an efficient score function estimation

    Science.gov (United States)

    Pishravian, Arash; Aghabozorgi Sahaf, Masoud Reza

    2012-12-01

    In this paper speech-music separation using Blind Source Separation is discussed. The separating algorithm is based on the mutual information minimization where the natural gradient algorithm is used for minimization. In order to do that, score function estimation from observation signals (combination of speech and music) samples is needed. The accuracy and the speed of the mentioned estimation will affect on the quality of the separated signals and the processing time of the algorithm. The score function estimation in the presented algorithm is based on Gaussian mixture based kernel density estimation method. The experimental results of the presented algorithm on the speech-music separation and comparing to the separating algorithm which is based on the Minimum Mean Square Error estimator, indicate that it can cause better performance and less processing time

  17. Survival, disabilities in activities of daily living, and physical and cognitive functioning among the oldest-old in China

    DEFF Research Database (Denmark)

    Zeng, Yi; Feng, Qiushi; Hesketh, Therese

    2017-01-01

    counterparts. INTERPRETATION: Advances in medications, lifestyle, and socioeconomics might compress activities of daily living disability, that is, benefits of success, but lifespan extension might expand disability of physical and cognitive functioning as more frail, elderly individuals survive with health......BACKGROUND: The oldest-old (those aged ≥80 years) are the most rapidly growing age group globally, and are most in need of health care and assistance. We aimed to assess changes in mortality, disability in activities of daily living, and physical and cognitive functioning among oldest...... age at the time of the assessment in the 1998 and 2008 surveys. Four health outcomes were investigated: annual death rate, Activities of Daily Living (ADL), physical performance in three tests and cognitive function measured by Mini-Mental State Examination (MMSE). We used different tests...

  18. Methodological issues in estimating survival in patients with multiple primary cancers: an application to women with breast cancer as a first tumour

    Directory of Open Access Journals (Sweden)

    Ricceri Fulvio

    2009-02-01

    Full Text Available Abstract Background Comparing survival of patients with a single tumour and patients with multiple primaries poses different methodological problems. In population based studies, where we cannot rely on detailed clinical information, the issue is disentangling the share of survival probability from the first and second cancer, and their compounded effect. We examined three hypotheses: A the survival probability since the first tumour does not change with the occurrence of a second tumour; B the probability of surviving a tumour does not change with the presence of a previous primary; C the probabilities of surviving two subsequent primary tumours are independent (additivity hypothesis on mortality rates. Methods We studied the survival probabilities modelling mortality rates according to hypotheses A, B and C. Mortality rates were calculated using Aalen-Johansen estimators which allowed to discount for the lag-time survival before developing a second tumour. We applied this approach to a cohort of 436 women with breast cancer (BC and a subsequent tumour in the resident population of Turin, Italy, between 1985 and 2002. Results We presented our results in term of a Standardised Mortality Ratio calculated (SMRAJ after 10 years of follow-up. For hypothesis A we observed a significant excess mortality of 2.21 (95% C.I. 1.94 – 2.45. Concerning hypothesis B we found a not significant SMRAJ of 0.98 (95% C.I. 0.87 – 1.10. The additivity hypothesis (C was not confirmed as it overestimated the risk of death, in fact SMRsAJ were all below 1: 0.75 (95% C.I. 0.66 – 0.84 for BC and all subsequent cancers, 0.72 (95% C.I. 0.55 – 0.94 for BC and colon-rectum cancer, 0.76 (95% C.I. 0.48 – 1.14 for BC and corpus uteri cancer (not significant. Conclusion This method proved to be useful in disentangling the effect of different subsequent cancers on mortality. In our application it shows a worse long-term mortality for women with two cancers than that with

  19. Nonparametric estimation of the stationary M/G/1 workload distribution function

    DEFF Research Database (Denmark)

    Hansen, Martin Bøgsted

    In this paper it is demonstrated how a nonparametric estimator of the stationary workload distribution function of the M/G/1-queue can be obtained by systematic sampling the workload process. Weak convergence results and bootstrap methods for empirical distribution functions for stationary...

  20. Nonparametric estimation of the stationary M/G/1 workload distribution function

    DEFF Research Database (Denmark)

    Hansen, Martin Bøgsted

    2005-01-01

    In this paper it is demonstrated how a nonparametric estimator of the stationary workload distribution function of the M/G/1-queue can be obtained by systematic sampling the workload process. Weak convergence results and bootstrap methods for empirical distribution functions for stationary...

  1. Using step and path selection functions for estimating resistance to movement: Pumas as a case study

    Science.gov (United States)

    Katherine A. Zeller; Kevin McGarigal; Samuel A. Cushman; Paul Beier; T. Winston Vickers; Walter M. Boyce

    2015-01-01

    GPS telemetry collars and their ability to acquire accurate and consistently frequent locations have increased the use of step selection functions (SSFs) and path selection functions (PathSFs) for studying animal movement and estimating resistance. However, previously published SSFs and PathSFs often do not accommodate multiple scales or multiscale modeling....

  2. Coefficient Estimates for Certain Subclasses of Biunivalent Functions Defined by Convolution

    Directory of Open Access Journals (Sweden)

    R. Vijaya

    2016-01-01

    Full Text Available We introduce two new subclasses of the function class Σ of biunivalent functions in the open disc defined by convolution. Estimates on the coefficients a2 and a3 for the two subclasses are obtained. Moreover, we verify Brannan and Clunie’s conjecture a2≤2 for our subclasses.

  3. Asymptotically optimal estimation of smooth functionals for interval censoring, case 2

    NARCIS (Netherlands)

    Groeneboom, P.; Geskus, R.

    1999-01-01

    For a version of the interval censoring model, case 2, in which the observation intervals are allowed to be arbitrarily small, we consider estimation of functionals that are differentiable along Hellinger differentiable paths. The asymptotic information lower bound for such functionals can be

  4. Improvement of Liver Function, Quality of Life and Survival after Insertion of Endoprosthesis in Advance Malignant Biliary Obstruction.

    Science.gov (United States)

    Ullah, A A; Rahman, A; Chowdhury, L H; Bhuiya, A H

    2017-01-01

    Obstructive jaundice due to advance malignancy is a fatal problem. It most commonly occurs at the distal common bile duct or at the hilum of liver. Magnetic Resonance Cholangio Pancreatography (MRCP) and Computed Tomography (CT) are most useful in identifying the underlying cause as well as localize the position of the stricture. For those patients with unresectable disease, progressive jaundice constitutes an immediate threat to their survival, in addition to significant loss to their quality of life secondary to pruritus, malaise and cholangitis. Effective and lasting decompression of the biliary tree is a priority and consists of positioning of a biliary endoprosthesis (stent). To observe the improvement of liver function, quality of life and survival after successful insertion of endoprosthesis (stenting) in malignant biliary obstruction, a study was performed in the department of surgery, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from September 2013 to August 2014, in 50 patients with clinically visible jaundice and unresectable disease. There were significant (p<0.001) reductions in the levels of serum bilirubin, serum alkaline phosphatase, serum SGPT and Prothrombin time from the time of admission to 2 weeks and 3 weeks after stenting. Physical and functional quality of life was greatly improved 2-4 weeks after stenting, where emotional quality remained the same throughout the study period. Successful palliation by stenting of malignant biliary obstruction is a priority to achieve improvements in liver function, quality of life and prolong survival. Endoscopic stent placement appears to be safe, well tolerated and can be offered without delay as a primary treatment option for all patients with unresectable malignant biliary lesion.

  5. How AMPK and PKA Interplay to Regulate Mitochondrial Function and Survival in Models of Ischemia and Diabetes

    Directory of Open Access Journals (Sweden)

    Jingdian Zhang

    2017-01-01

    Full Text Available Adenosine monophosphate-activated protein kinase (AMPK is a conserved, redox-activated master regulator of cell metabolism. In the presence of oxidative stress, AMPK promotes cytoprotection by enhancing the conservation of energy by suppressing protein translation and by stimulating autophagy. AMPK interplays with protein kinase A (PKA to regulate oxidative stress, mitochondrial function, and cell survival. AMPK and dual-specificity A-kinase anchoring protein 1 (D-AKAP1, a mitochondrial-directed scaffold of PKA, interact to regulate mitochondrial function and oxidative stress in cardiac and endothelial cells. Ischemia and diabetes, a chronic disease that increases the onset of cardiovascular diseases, suppress the cardioprotective effects of AMPK and PKA. Here, we review the molecular mechanisms by which AMPK and D-AKAP1/PKA interplay to regulate mitochondrial function, oxidative stress, and signaling pathways that prime endothelial cells, cardiac cells, and neurons for cytoprotection against oxidative stress. We discuss recent literature showing how temporal dynamics and localization of activated AMPK and PKA holoenzymes play a crucial role in governing cellular bioenergetics and cell survival in models of ischemia, cardiovascular diseases, and diabetes. Finally, we propose therapeutic strategies that tout localized PKA and AMPK signaling to reverse mitochondrial dysfunction, oxidative stress, and death of neurons and cardiac and endothelial cells during ischemia and diabetes.

  6. Modality of RRT and Recovery of Kidney Function after AKI in Patients Surviving to Hospital Discharge.

    Science.gov (United States)

    Liang, Kelly V; Sileanu, Florentina E; Clermont, Gilles; Murugan, Raghavan; Pike, Francis; Palevsky, Paul M; Kellum, John A

    2016-01-07

    Observational evidence has suggested that RRT modality may affect recovery after AKI. It is unclear whether initial choice of intermittent hemodialysis or continuous RRT affects renal recovery, survival, or development of ESRD in critically ill patients when modality choice is made primarily on hemodynamics. We performed a retrospective cohort study examining adults (≥18 years old) admitted to intensive care units from 2000 to 2008 who received RRT for AKI and survived to hospital discharge or 90 days. We analyzed renal recovery (alive and not requiring RRT) and reasons for nonrecovery (death or ESRD) at 90 and 365 days. Conditional multivariable logistic regression was used to assess differences in renal recovery at 90 and 365 days between continuous RRT and intermittent hemodialysis. Models were stratified by propensity for continuous RRT and adjusted for age and reference creatinine. Of 4738 patients with Kidney Disease Improving Global Outcomes stage 3 AKI, 1338 (28.2%) received RRT, and 638 (47.7%) survived to hospital discharge (353 intermittent hemodialysis and 285 continuous RRT). Recovery from AKI was lower for intermittent hemodialysis versus continuous RRT at 90 days (66.6% intermittent hemodialysis versus 75.4% continuous RRT; P=0.02) but similar at 365 days (54.1% intermittent hemodialysis versus 59.6% continuous RRT; P=0.17). In multivariable analysis, there was no difference in odds of recovery at 90 or 365 days for patients initially treated with continuous RRT versus intermittent hemodialysis (90 days: odds ratio, 1.19; 95% confidence interval, 0.91 to 1.55; P=0.20; 365 days: odds ratio, 0.93; 95% confidence interval, 0.72 to 1.2; P=0.55). We found no significant difference in hazards for nonrecovery or reasons for nonrecovery (mortality or ESRD) with intermittent hemodialysis versus continuous RRT. These results suggest that, when initial RRT modality is chosen primarily on hemodynamics, renal recovery and clinical outcomes in survivors are

  7. The Bacillus subtilis sigma(X) protein is an extracytoplasmic function sigma factor contributing to survival at high temperature.

    OpenAIRE

    Huang, X; Decatur, A; Sorokin, A.; Helmann, J D

    1997-01-01

    The sigX gene, identified as part of the international effort to sequence the Bacillus subtilis genome, has been proposed to encode an alternative sigma factor of the extracytoplasmic function (ECF) subfamily. The sigX gene is cotranscribed with a downstream gene, ypuN, during logarithmic and early stationary phases of growth. We now report that strains lacking sigma(X) are impaired in the ability to survive at high temperature whereas a ypuN mutant has increased thermotolerance. We overprodu...

  8. Estimating Contrast Transfer Function and Associated Parameters by Constrained Nonlinear Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chao; Jiang, Wen; Chen, Dong-Hua; Adiga, Umesh; Ng, Esmond G.; Chiu, Wah

    2008-07-28

    The three-dimensional reconstruction of macromolecules from two-dimensional single-particle electron images requires determination and correction of the contrast transfer function (CTF) and envelope function. A computational algorithm based on constrained non-linear optimization is developed to estimate the essential parameters in the CTF and envelope function model simultaneously and automatically. The application of this estimation method is demonstrated with focal series images of amorphous carbon film as well as images of ice-embedded icosahedral virus particles suspended across holes.

  9. Cognitive function, stress hormones, heart rate and nutritional status during simulated captivity in military survival training.

    Science.gov (United States)

    Lieberman, Harris R; Farina, Emily K; Caldwell, John; Williams, Kelly W; Thompson, Lauren A; Niro, Philip J; Grohmann, Kyle A; McClung, James P

    2016-10-15

    Stress influences numerous psychological and physiological processes, and its effects have practical implications in a variety of professions and real-world activities. However, few studies have concurrently assessed multiple behavioral, hormonal, nutritional and heart-rate responses of humans to acute, severe stress. This investigation simultaneously assessed cognitive, affective, hormonal, and heart-rate responses induced by an intensely stressful real-world environment designed to simulate wartime captivity. Sixty males were evaluated during and immediately following participation in U.S. Army Survival, Evasion, Resistance, and Escape (SERE) school, three weeks of intense but standardized training for Soldiers at risk of capture. Simulated captivity and intense mock interrogations degraded grammatical reasoning (pworking memory (pnutritional status and heart rate are simultaneously altered, and each of these subsequently recovers at different rates. Published by Elsevier Inc.

  10. The regulation of function, growth and survival of GLP-1-producing L-cells

    DEFF Research Database (Denmark)

    Kuhre, Rune Ehrenreich; Holst, Jens Juul; Kappe, Camilla

    2016-01-01

    Glucagon-like peptide-1 (GLP-1) is a peptide hormone, released from intestinal L-cells in response to hormonal, neural and nutrient stimuli. In addition to potentiation of meal-stimulated insulin secretion, GLP-1 signalling exerts numerous pleiotropic effects on various tissues, regulating energy...... absorption and disposal, as well as cell proliferation and survival. In Type 2 Diabetes (T2D) reduced plasma levels of GLP-1 have been observed, and plasma levels of GLP-1, as well as reduced numbers of GLP-1 producing cells, have been correlated to obesity and insulin resistance. Increasing endogenous...... secretion of GLP-1 by selective targeting of the molecular mechanisms regulating secretion from the L-cell has been the focus of much recent research. An additional and promising strategy for enhancing endogenous secretion may be to increase the L-cell mass in the intestinal epithelium, but the mechanisms...

  11. Design and Analysis of Salmonid Tagging Studies in the Columbia Basin, Volume XXI; A Summary of Methods for Conducting Salmonid Fry Mark-Recapture Studies for Estimating Survival in Tributaries, Technical Report 2005-2006.

    Energy Technology Data Exchange (ETDEWEB)

    Skalski, John

    2007-02-01

    Productivity and early fry survival can have a major influence on the dynamics of fish stocks. To investigate the early life history of fish, numerous methods have been developed or adapted to these much smaller fish. Some of the marking techniques provide individual identification; many others, only class identification. Some of the tagging techniques require destructive sampling to identify a mark; other methods permit benign examination and rerelease of captured fish. Sixteen alternative release-recapture designs for conducting fry survival investigations were examined. Eleven approaches were found capable of estimating survival parameters; five were not. Of those methods capable of estimating fry survival, five required unique marks, four required batch-specific marks, and two approaches required remarking and rereleasing captured fry. No approach based on a simple batch mark was capable of statistically estimating survival.

  12. Instrumental variables estimation of exposure effects on a time-to-event response using structural cumulative survival models

    DEFF Research Database (Denmark)

    Martinussen, T.; Vansteelandt, S.; Tchetgen, E. J. Tchetgen

    2016-01-01

    The use of instrumental variables for estimating the effect of an exposure on an outcome is popular in econometrics, and increasingly so in epidemiology. This increasing popularity may be attributed to the natural occurrence of instrumental variables in observational studies that incorporate...... elements of randomization, either by design or by nature (e.g., random inheritance of genes). Instrumental variables estimation of exposure effects is well established for continuous outcomes and to some extent for binary outcomes. It is, however, largely lacking for time-to-event outcomes because......-parametric variant of the instrumental variables additive hazards model. We propose a class of recursive instrumental variable estimators for these exposure effects, and derive their large sample properties along with inferential tools. We examine the performance of the proposed method in simulation studies...

  13. Surviving a brain tumor in childhood : impact on family functioning in adolescence

    NARCIS (Netherlands)

    Beek, Laura; Schappin, R; Gooskens, Rob; Huisman, Jaap; Jongmans, Marian

    ObjectiveTo investigate family functioning in families with an adolescent survivor of a pediatric brain tumor. We explored whether adolescent, parent, disease and treatment factors, and demographic characteristics predicted family functioning. MethodsIn this cross-sectional study, 45 adolescent

  14. Oxygen Administration Improves Survival but Worsens Cardiopulmonary Functions in Chlorine-exposed Rats.

    Science.gov (United States)

    Okponyia, Obiefuna C; McGraw, Matthew D; Dysart, Marilyn M; Garlick, Rhonda B; Rioux, Jacqueline S; Murphy, Angela L; Roe, Gates B; White, Carl W; Veress, Livia A

    2018-01-01

    Chlorine is a highly reactive gas that can cause significant injury when inhaled. Unfortunately, its use as a chemical weapon has increased in recent years. Massive chlorine inhalation can cause death within 4 hours of exposure. Survivors usually require hospitalization after massive exposure. No countermeasures are available for massive chlorine exposure and supportive-care measures lack controlled trials. In this work, adult rats were exposed to chlorine gas (LD 58-67 ) in a whole-body exposure chamber, and given oxygen (0.8 Fi O 2 ) or air (0.21 Fi O 2 ) for 6 hours after baseline measurements were obtained. Oxygen saturation, vital signs, respiratory distress and neuromuscular scores, arterial blood gases, and hemodynamic measurements were obtained hourly. Massive chlorine inhalation caused severe acute respiratory failure, hypoxemia, decreased cardiac output, neuromuscular abnormalities (ataxia and hypotonia), and seizures resulting in early death. Oxygen improved survival to 6 hours (87% versus 42%) and prevented observed seizure-related deaths. However, oxygen administration worsened the severity of acute respiratory failure in chlorine-exposed rats compared with controls, with increased respiratory acidosis (pH 6.91 ± 0.04 versus 7.06 ± 0.01 at 2 h) and increased hypercapnia (180.0 ± 19.8 versus 103.2 ± 3.9 mm Hg at 2 h). In addition, oxygen did not improve neuromuscular abnormalities, cardiac output, or respiratory distress associated with chlorine exposure. Massive chlorine inhalation causes severe acute respiratory failure and multiorgan damage. Oxygen administration can improve short-term survival but appears to worsen respiratory failure, with no improvement in cardiac output or neuromuscular dysfunction. Oxygen should be used with caution after massive chlorine inhalation, and the need for early assisted ventilation should be assessed in victims.

  15. Estimates of solutions for parabolic differential and difference functional equations and applications

    OpenAIRE

    Lucjan Sapa

    2012-01-01

    The theorems on the estimates of solutions for nonlinear second-order partial differential functional equations of parabolic type with Dirichlet's condition and for suitable implicit finite difference functional schemes are proved. The proofs are based on the comparison technique. The convergent and stable difference method is considered without the assumption of the global generalized Perron condition posed on the functional variable but with the local one only. It is a consequence of our es...

  16. Analytical estimation of distance-disorientation function of the material microstructure

    Science.gov (United States)

    Staraselski, Yauheni; Brahme, Abhijit; Inal, Kaan; Mishra, Raja K.

    2013-08-01

    This work presents a new functional approach to estimate the distance-disorientation correlation function of a given microstructure. The proposed approach separates the crystallographic domain into texture defined by its Euler angles ( ? ) and geometrical domain defined by distance distribution function ? . The crystallographic domain is treated as independent (known) variable and an analytical estimate for the Euclidian distance distribution function ? is obtained. The proposed analytical solution for the estimation of ? is based on existing statistical growth models and the logistic probability distribution function. The solution is optimized for the measured experimental data and takes into account morphological features of the microstructure such as grain volume, grain radius and grain size as well as their distribution inside the material. An analytical model is proposed for constructing the distance-disorientation function (DDF) using the estimated Euclidian distance between pixel pairs. The new functional solution is a highly effective way to calculate DDF values, making it suitable for application to the real microstructure optimization problems. The DDF obtained by using the results of probabilistic solution is validated by comparing them with the DDF obtained from experimental electron back-scatter diffraction data.

  17. Evaluating the Impact of Zimbabwe's Prevention of Mother-to-Child HIV Transmission Program: Population-Level Estimates of HIV-Free Infant Survival Pre-Option A.

    Directory of Open Access Journals (Sweden)

    Raluca Buzdugan

    Full Text Available We estimated HIV-free infant survival and mother-to-child HIV transmission (MTCT rates in Zimbabwe, some of the first community-based estimates from a UNAIDS priority country.In 2012 we surveyed mother-infant pairs residing in the catchment areas of 157 health facilities randomly selected from 5 of 10 provinces in Zimbabwe. Enrolled infants were born 9-18 months before the survey. We collected questionnaires, blood samples for HIV testing, and verbal autopsies for deceased mothers/infants. Estimates were assessed among i all HIV-exposed infants, as part of an impact evaluation of Option A of the 2010 WHO guidelines (rolled out in Zimbabwe in 2011, and ii the subgroup of infants unexposed to Option A. We compared province-level MTCT rates measured among women in the community with MTCT rates measured using program monitoring data from facilities serving those communities.Among 8568 women with known HIV serostatus, 1107 (12.9% were HIV-infected. Among all HIV-exposed infants, HIV-free infant survival was 90.9% (95% confidence interval (CI: 88.7-92.7 and MTCT was 8.8% (95% CI: 6.9-11.1. Sixty-six percent of HIV-exposed infants were still breastfeeding. Among the 762 infants born before Option A was implemented, 90.5% (95% CI: 88.1-92.5 were alive and HIV-uninfected at 9-18 months of age, and 9.1% (95%CI: 7.1-11.7 were HIV-infected. In four provinces, the community-based MTCT rate was higher than the facility-based MTCT rate. In Harare, the community and facility-based rates were 6.0% and 9.1%, respectively.By 2012 Zimbabwe had made substantial progress towards the elimination of MTCT. Our HIV-free infant survival and MTCT estimates capture HIV transmissions during pregnancy, delivery and breastfeeding regardless of whether or not mothers accessed health services. These estimates also provide a baseline against which to measure the impact of Option A guidelines (and subsequently Option B+.

  18. Regional left ventricular function does not predict survival in ischaemic cardiomyopathy after cardiac surgery.

    Science.gov (United States)

    Prior, David L; Stevens, Susanna R; Holly, Thomas A; Krejca, Michal; Paraforos, Alexandros; Pohost, Gerald M; Byrd, Krysti; Kukulski, Tomasz; Jones, Robert H; Desvigne-Nickens, Patrice; Varadarajan, Padmini; Amanullah, Aman; Lin, Grace; Al-Khalidi, Hussein R; Aldea, Gabriel; Santambrogio, Carlo; Bochenek, Andrzej; Berman, Daniel S

    2017-09-01

    To define the prognostic contribution of global and regional left ventricular (LV) function measurements in patients with ischaemic cardiomyopathy randomised to coronary artery bypass graft surgery (CABG) with (n=501) or without (n=499) surgical ventricular reconstruction (SVR). Novel multivariable methods to analyse global and regional LV systolic function were used to better formulate prediction models for long-term mortality following CABG with or without SVR in the entire cohort of 1000 randomised SVR hypothesis patients. Key clinical variables were included in the analysis. Regional function was classified according to the discreteness of anteroapical hypokinesia and akinesia into those most likely to benefit from SVR, those least likely and those felt to have intermediate likelihood of benefit from SVR. The most prognostic clinical variables identified in multivariable models include creatinine, LV end-systolic volume index (ESVI), age and NYHA (New York Heart Association) class. Addition of LV ejection fraction, LV end-diastolic volume index and regional function assessment did not contribute additional power to the model. Subgroup analysis based on regional function did not identify a cohort in which SVR improved mortality. ESVI is the single parameter of LV function most predictive of mortality in patients with LV systolic dysfunction following CABG with or without SVR in multivariable models that include all key clinical and LV systolic function parameters. Assessment of regional cardiac function does not enhance prediction of mortality nor identify a subgroup for which SVR improves mortality. These results do not support elective addition of LV reconstruction surgery in patients undergoing CABG. NCT00023595. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  19. Collagen esterification enhances the function and survival of pancreatic β cells in 2D and 3D culture systems

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jae Hyung [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Kim, Yang Hee [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Jeong, Seong Hee; Lee, Song [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Park, Si-Nae [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Shim, In Kyong, E-mail: shimiink@gmail.com [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Kim, Song Cheol, E-mail: drksc@amc.seoul.kr [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Department of Surgery, University of Ulsan College of Medicine & Asan Medical Center, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of)

    2015-08-07

    Collagen, one of the most important components of the extracellular matrix (ECM), may play a role in the survival of pancreatic islet cells. In addition, chemical modifications that change the collagen charge profile to a net positive charge by esterification have been shown to increase the adhesion and proliferation of various cell types. The purpose of this study was to characterize and compare the effects of native collagen (NC) and esterified collagen (EC) on β cell function and survival. After isolation by the collagenase digestion technique, rat islets were cultured with NC and EC in 2 dimensional (2D) and 3 dimensional (3D) environments for a long-term duration in vitro. The cells were assessed for islet adhesion, morphology, viability, glucose-induced insulin secretion, and mRNA expression of glucose metabolism-related genes, and visualized by scanning electron microscopy (SEM). Islet cells attached tightly in the NC group, but islet cell viability was similar in both the NC and EC groups. Glucose-stimulated insulin secretion was higher in the EC group than in the NC group in both 2D and 3D culture. Furthermore, the mRNA expression levels of glucokinase in the EC group were higher than those in the NC group and were associated with glucose metabolism and insulin secretion. Finally, SEM observation confirmed that islets had more intact component cells on EC sponges than on NC sponges. These results indicate that modification of collagen may offer opportunities to improve function and viability of islet cells. - Highlights: • We changed the collagen charge profile to a net positive charge by esterification. • Islets cultured on esterified collagen improved survival in both 2D and 3D culture. • Islets cultured on esterified collagen enhanced glucose-stimulated insulin release. • High levels of glucokinase mRNA may be associated with increased insulin release.

  20. Impact of Trough Levels of Tacrolimus on Kidney Function and Graft Survival in Short and Longer Periods After Renal Transplantation.

    Science.gov (United States)

    Žilinská, Z; Dedinská, I; Breza, J; Laca, L

    2016-10-01

    Optimizing immunosuppressive treatment in the early posttransplant period is important for achieving long-term graft function and survival. There were 205 renal transplant recipients involved in this study. Patients were divided into groups according to the induction therapy (no induction vs basiliximab/daclizumab vs rabbit antithymocyte globulin), maintenance therapy at the time of transplantation (tacrolimus [TAC] vs cyclosporine), the average trough TAC levels in months 4 to 6 after TO and serum creatinine 5 years after renal transplantation. The incidence of acute rejection was significantly higher in cyclosporine than in TAC group of patients (P = .0364). The average TAC levels on elapsed time after transplantation significantly decreased (P < .0001). Five years after renal transplantation, there were higher TAC levels (5.6 ± 0.7 ng/mL) in the group with "zero" low levels than in the group with "zero" high levels (4.6 ± 1.1 ng/mL), which was statistically significant (P < .0001). We did not find any difference in graft and patient survival in posttransplant years 2 to 5 according to TAC levels or the induction treatment. In our study, we have confirmed that better graft function 5 years after transplantation was connected with higher trough tacrolimus levels on elapsed time after renal transplantation. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. A Three-Dimensional Culture System with Matrigel Promotes Purified Spiral Ganglion Neuron Survival and Function In Vitro.

    Science.gov (United States)

    Yan, Wenqing; Liu, Wenwen; Qi, Jieyu; Fang, Qiaojun; Fan, Zhaomin; Sun, Gaoying; Han, Yuechen; Zhang, Daogong; Xu, Lei; Wang, Mingming; Li, Jianfeng; Chen, Fangyi; Liu, Dong; Chai, Renjie; Wang, Haibo

    2017-03-10

    In vitro culture of spiral ganglion neurons (SGNs) is a useful approach to investigate numerous aspects of neuronal behavior and to identify potential therapeutic targets for SGN protection and regeneration. However, the isolation of SGNs and the long-term maintenance of their structure and function in vitro remain challenging. In this study, we isolated SGNs from Bhlhb5-cre and Rosa26-tdTomato mice with fluorescence-activated cell sorting and determined the cell purity. We then encapsulated the pure SGNs in matrigel and cultured the SGNs in vitro. We found that the three-dimensional (3D)-matrigel culture environment significantly suppressed apoptosis and improved SGN survival in vitro, which enabled the long-term culture of SGNs for up to 6 months. The 3D-matrigel system also significantly promoted neurite outgrowth of the SGNs, increased the cells' polarity, promoted the area of growth cones, and significantly increased the synapse density of the SGNs. More importantly, the 3D-matrigel system helped to maintain and promote the electrophysiological properties of the SGNs. In conclusion, the 3D-matrigel culture system promoted the survival of purified SGNs in vitro and maintained their morphological structure and function and thus could be a useful tool for studying the physiology and pathophysiology of purified SGNs in long-term culture.

  2. On the a priori estimation of collocation error covariance functions: a feasibility study

    DEFF Research Database (Denmark)

    Arabelos, D.N.; Forsberg, René; Tscherning, C.C.

    2007-01-01

    and the associated error covariance functions were conducted in the Arctic region north of 64 degrees latitude. The correlation between the known features of the data and the parameters variance and correlation length of the computed error covariance functions was estimated using multiple regression analysis......Error covariance estimates are necessary information for the combination of solutions resulting from different kinds of data or methods, or for the assimilation of new results in already existing solutions. Such a combination or assimilation process demands proper weighting of the data, in order...... for the combination to be optimal and the error estimates of the results realistic. One flexible method for the gravity field approximation is least-squares collocation leading to optimal solutions for the predicted quantities and their error covariance estimates. The drawback of this method is related to the current...

  3. Estimation of EVA Mode Choice Model Parameters with Different Types of Utility Functions

    Directory of Open Access Journals (Sweden)

    Tomaž Maher

    2011-05-01

    Full Text Available This paper presents the estimation of nine types of utility function parameters for the application in EVA mode choice model for the city of Ljubljana, Slovenia. Four different modes (private car, public transport, bike and walking and five purposes (work, education, shopping, leisure and other were taken into consideration. This paper presents first the design of the Stated Preference survey, then a brief review of the EVA model, different types of utility functions and the estimation method. The final log-likelihood enables comparison of different types of utility functions. The results show that absolute differences in final log-likelihood among most types of utility functions are not high despite the different shapes, which implies that different functions may best describe different variables.

  4. Self-consistent nonparametric maximum likelihood estimator of the bivariate survivor function

    OpenAIRE

    R. L. Prentice

    2014-01-01

    As usually formulated the nonparametric likelihood for the bivariate survivor function is overparameterized, resulting in uniqueness problems for the corresponding nonparametric maximum likelihood estimator. Here the estimation problem is redefined to include parameters for marginal hazard rates, and for double failure hazard rates only at informative uncensored failure time grid points where there is pertinent empirical information. Double failure hazard rates at other grid points in the ris...

  5. Why one needs a functional renormalization group to survive in a ...

    Indian Academy of Sciences (India)

    We choose the disorder at the microscopic scale to be Gaussian, with correlations. V (x, u)V (x ,u ) := δd(x − x ) ... dimensional reduction implies that the disorder-averaged 2-point function at zero temperature is ..... [20] S Scheidl, Private communication about 2-loop calculations for the random manifold problem (2000–2004).

  6. Accumulation of Mitochondrial DNA Mutations Disrupts Cardiac Progenitor Cell Function and Reduces Survival.

    Science.gov (United States)

    Orogo, Amabel M; Gonzalez, Eileen R; Kubli, Dieter A; Baptista, Igor L; Ong, Sang-Bing; Prolla, Tomas A; Sussman, Mark A; Murphy, Anne N; Gustafsson, Åsa B

    2015-09-04

    Transfer of cardiac progenitor cells (CPCs) improves cardiac function in heart failure patients. However, CPC function is reduced with age, limiting their regenerative potential. Aging is associated with numerous changes in cells including accumulation of mitochondrial DNA (mtDNA) mutations, but it is unknown how this impacts CPC function. Here, we demonstrate that acquisition of mtDNA mutations disrupts mitochondrial function, enhances mitophagy, and reduces the replicative and regenerative capacities of the CPCs. We show that activation of differentiation in CPCs is associated with expansion of the mitochondrial network and increased mitochondrial oxidative phosphorylation. Interestingly, mutant CPCs are deficient in mitochondrial respiration and rely on glycolysis for energy. In response to differentiation, these cells fail to activate mitochondrial respiration. This inability to meet the increased energy demand leads to activation of cell death. These findings demonstrate the consequences of accumulating mtDNA mutations and the importance of mtDNA integrity in CPC homeostasis and regenerative potential. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Why one needs a functional renormalization group to survive in a ...

    Indian Academy of Sciences (India)

    In this paper, we discuss why functional renormalization is an essential tool to treat strongly disordered systems. More specifically, we treat elastic manifolds in a disordered environment. These are governed by a disorder distribution, which after a finite renormalization becomes non-analytic, thus overcoming the predictions ...

  8. Geriatric Conditions in Acutely Hospitalized Older Patients: Prevalence and One-Year Survival and Functional Decline

    NARCIS (Netherlands)

    Buurman, B.M.; Hoogerduijn, J.G.; de Haan, R.J.; Abu-Hanna, A.; Lagaay, A.M.; Verhaar, H.J.; Schuurmans, M.J.; Levi, M.; de Rooij, S.E.

    2011-01-01

    Background: To study the prevalence of eighteen geriatric conditions in older patients at admission, their reporting rate in discharge summaries and the impact of these conditions on mortality and functional decline one year after admission. Method: A prospective multicenter cohort study conducted

  9. Geriatric Conditions in Acutely Hospitalized Older Patients: Prevalence and One-Year Survival and Functional Decline

    Science.gov (United States)

    Buurman, Bianca M.; Hoogerduijn, Jita G.; de Haan, Rob J.; Abu-Hanna, Ameen; Lagaay, A. Margot; Verhaar, Harald J.; Schuurmans, Marieke J.; Levi, Marcel; de Rooij, Sophia E.

    2011-01-01

    Background To study the prevalence of eighteen geriatric conditions in older patients at admission, their reporting rate in discharge summaries and the impact of these conditions on mortality and functional decline one year after admission. Method A prospective multicenter cohort study conducted between 2006 and 2008 in two tertiary university teaching hospitals and one regional teaching hospital in the Netherlands. Patients of 65 years and older, acutely admitted and hospitalized for at least 48 hours, were invited to participate. Eighteen geriatric conditions were assessed at hospital admission, and outcomes (mortality, functional decline) were assessed one year after admission. Results 639 patients were included, with a mean age of 78 years. IADL impairment (83%), polypharmacy (61%), mobility difficulty (59%), high levels of primary caregiver burden (53%), and malnutrition (52%) were most prevalent. Except for polypharmacy and cognitive impairment, the reporting rate of the geriatric conditions in discharge summaries was less than 50%. One year after admission, 35% had died and 33% suffered from functional decline. A high Charlson comorbidity index score, presence of malnutrition, high fall risk, presence of delirium and premorbid IADL impairment were associated with mortality and overall poor outcome (mortality or functional decline). Obesity lowered the risk for mortality. Conclusion Geriatric conditions were highly prevalent and associated with poor health outcomes after admission. Early recognition of these conditions in acutely hospitalized older patients and improving the handover to the general practitioner could lead to better health outcomes and reduce the burden of hospital admission for older patients. PMID:22110598

  10. A Functional Analysis Framework for Modeling, Estimation and Control in Science and Engineering

    CERN Document Server

    Banks, HT

    2012-01-01

    A Modern Framework Based on Time-Tested Material A Functional Analysis Framework for Modeling, Estimation and Control in Science and Engineering presents functional analysis as a tool for understanding and treating distributed parameter systems. Drawing on his extensive research and teaching from the past 20 years, the author explains how functional analysis can be the basis of modern partial differential equation (PDE) and delay differential equation (DDE) techniques. Recent Examples of Functional Analysis in Biology, Electromagnetics, Materials, and Mechanics Through numerous application exa

  11. Estimation of parameters of constant elasticity of substitution production functional model

    Science.gov (United States)

    Mahaboob, B.; Venkateswarlu, B.; Sankar, J. Ravi

    2017-11-01

    Nonlinear model building has become an increasing important powerful tool in mathematical economics. In recent years the popularity of applications of nonlinear models has dramatically been rising up. Several researchers in econometrics are very often interested in the inferential aspects of nonlinear regression models [6]. The present research study gives a distinct method of estimation of more complicated and highly nonlinear model viz Constant Elasticity of Substitution (CES) production functional model. Henningen et.al [5] proposed three solutions to avoid serious problems when estimating CES functions in 2012 and they are i) removing discontinuities by using the limits of the CES function and its derivative. ii) Circumventing large rounding errors by local linear approximations iii) Handling ill-behaved objective functions by a multi-dimensional grid search. Joel Chongeh et.al [7] discussed the estimation of the impact of capital and labour inputs to the gris output agri-food products using constant elasticity of substitution production function in Tanzanian context. Pol Antras [8] presented new estimates of the elasticity of substitution between capital and labour using data from the private sector of the U.S. economy for the period 1948-1998.

  12. Bias Errors due to Leakage Effects When Estimating Frequency Response Functions

    Directory of Open Access Journals (Sweden)

    Andreas Josefsson

    2012-01-01

    Full Text Available Frequency response functions are often utilized to characterize a system's dynamic response. For a wide range of engineering applications, it is desirable to determine frequency response functions for a system under stochastic excitation. In practice, the measurement data is contaminated by noise and some form of averaging is needed in order to obtain a consistent estimator. With Welch's method, the discrete Fourier transform is used and the data is segmented into smaller blocks so that averaging can be performed when estimating the spectrum. However, this segmentation introduces leakage effects. As a result, the estimated frequency response function suffers from both systematic (bias and random errors due to leakage. In this paper the bias error in the H1 and H2-estimate is studied and a new method is proposed to derive an approximate expression for the relative bias error at the resonance frequency with different window functions. The method is based on using a sum of real exponentials to describe the window's deterministic autocorrelation function. Simple expressions are derived for a rectangular window and a Hanning window. The theoretical expressions are verified with numerical simulations and a very good agreement is found between the results from the proposed bias expressions and the empirical results.

  13. Survival trends and predictors of mortality in severe pelvic trauma: estimates from the German Pelvic Trauma Registry Initiative.

    Science.gov (United States)

    Pohlemann, Tim; Stengel, Dirk; Tosounidis, Georgios; Reilmann, Heinrich; Stuby, Fabian; Stöckle, Uli; Seekamp, Andreas; Schmal, Hagen; Thannheimer, Andreas; Holmenschlager, Francis; Gänsslen, Axel; Rommens, Pol Maria; Fuchs, Thomas; Baumgärtel, Friedel; Marintschev, Ivan; Krischak, Gert; Wunder, Stephan; Tscherne, Harald; Culemann, Ulf

    2011-10-01

    To determine longitudinal trends in mortality, and the contribution of specific injury characteristics and treatment modalities to the risk of a fatal outcome after severe and complex pelvic trauma. We studied 5048 patients with pelvic ring fractures enrolled in the German Pelvic Trauma Registry Initiative between 1991 and 1993, 1998 and 2000, and 2004 and 2006. Complete datasets were available for 5014 cases, including 508 complex injuries, defined as unstable fractures with severe peri-pelvic soft tissue and organ laceration. Multivariable mixed-effects logistic regression analysis was employed to evaluate the impact of demographic, injury- and treatment-associated variables on all-cause in-hospital mortality. All-cause in-hospital mortality declined from 8% (39/466) in 1991 to 5% (33/638) in 2006. Controlling for age, Injury Severity Score, pelvic vessel injury, the need for emergency laparotomy, and application of a pelvic clamp, the odds ratio (OR) per annum was 0.94 (95% confidence interval [CI] 0.91-0.96). However, the risk of death did not decrease significantly in patients with complex injuries (OR 0.98, 95% CI 0.93-1.03). Raw mortality associated with this type of injury was 18% (95% CI 9-32%) in 2006. In contrast to an overall decline in trauma mortality, complex pelvic ring injuries remain associated with a significant risk of death. Awareness of this potentially life-threatening condition should be increased amongst trauma care professionals, and early management protocols need to be implemented to improve the survival prognosis. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Distinct Functional Domains of UBC9 Dictate Cell Survival and Resistance to Genotoxic Stress

    Energy Technology Data Exchange (ETDEWEB)

    Van Waardenburg,R.; Duda, D.; Lancaster, C.; Schulman, B.; Bjornsti, M.

    2006-01-01

    Covalent modification with SUMO alters protein function, intracellular localization, or protein-protein interactions. Target recognition is determined, in part, by the SUMO E2 enzyme, Ubc9, while Siz/Pias E3 ligases may facilitate select interactions by acting as substrate adaptors. A yeast conditional Ubc9P{sub 123}L mutant was viable at 36 C yet exhibited enhanced sensitivity to DNA damage. To define functional domains in Ubc9 that dictate cellular responses to genotoxic stress versus those necessary for cell viability, a 1.75- Angstroms structure of yeast Ubc9 that demonstrated considerable conservation of backbone architecture with human Ubc9 was solved. Nevertheless, differences in side chain geometry/charge guided the design of human/yeast chimeras, where swapping domains implicated in (i) binding residues within substrates that flank canonical SUMOylation sites, (ii) interactions with the RanBP2 E3 ligase, and (iii) binding of the heterodimeric E1 and SUMO had distinct effects on cell growth and resistance to DNA-damaging agents. Our findings establish a functional interaction between N-terminal and substrate-binding domains of Ubc9 and distinguish the activities of E3 ligases Siz1 and Siz2 in regulating cellular responses to genotoxic stress.

  15. Simvastatin pre-treatment improves survival and mitochondrial function in a 3-day fluid-resuscitated rat model of sepsis.

    Science.gov (United States)

    Morel, Jerome; Hargreaves, Iain; Brealey, David; Neergheen, Viruna; Backman, Janne T; Lindig, Sandro; Bläss, Marcus; Bauer, Michael; McAuley, Daniel F; Singer, Mervyn

    2017-04-25

    Statins may offer protective effects in sepsis through anti-inflammatory, mitochondrial protection and other actions. We thus evaluated the effects of simvastatin on survival, organ and mitochondrial function, tissue and plasma ubiquinone levels and liver transcriptomics in a 3-day rat model of sepsis. Comparisons of rat plasma simvastatin and ubiquinone levels were made against levels sampled in blood from patients with acute lung injury (ALI) enrolled into a trial of statin therapy. Animals received simvastatin by gavage either pre- or post-induction of faecal peritonitis. Control septic animals received vehicle alone. Seventy-two-hour survival was significantly greater in statin pre-treated animals (43.7%) compared with their statin post-treated (12.5%) and control septic (25%) counterparts (Psimvastatin pre- and post-treatment prevented the fall in mitochondrial oxygen consumption in muscle fibres taken from septic animals at 24 h. This beneficial effect was paralleled by recovery of genes related to fatty acid metabolism. Simvastatin pre-treatment resulted in a significant decrease in myocardial ubiquinone. Patients with ALI had a marked variation in plasma simvastatin acid levels; however, their ubiquinone/low-density lipoprotein (LDL) cholesterol ratio did not differ regardless of whether they were receiving statin or placebo. In summary, despite protective effects seen with statin treatment given both pre- and post-insult, survival benefit was only seen with pre-treatment, reflecting experiences in patient studies. © 2017 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  16. Effects of functionalized fullerenes on bifenthrin and tribufos toxicity to Daphnia magna: Survival, reproduction, and growth rate.

    Science.gov (United States)

    Brausch, Kathryn A; Anderson, Todd A; Smith, Philip N; Maul, Jonathan D

    2010-11-01

    Incorporation of carbon nanomaterials into industrial and consumer products is increasing, yet their impact on aquatic ecosystems alone and in chemical mixtures is largely unknown. Carbon nanomaterials may be found in the aquatic environment as mixtures with pesticides because of their proposed use in agriculture as smart delivery systems and nanosensors. The interaction effects of a functionalized fullerene ([1,2-methanofullerene C₆₀]-61-carboxylic acid) (fC₆₀) at 52.8 µg/L and the hydrophobic pesticides bifenthrin and tribufos were examined. The test organism was Daphnia magna, and response variables included 48-h survival, reproduction (bifenthrin, 70-d; tribufos, 21-d), and 10-d growth. Both pesticides reduced D. magna survival and reproduction (p Fullerenes significantly increased bifenthrin acute toxicity but did not significantly affect chronic endpoints or growth (p > 0.05). Median lethal concentrations (LC50s), median inhibition concentrations (IC50s) for days surviving, and IC50s for reproduction were 0.86, 0.55, and 0.49 µg/L for bifenthrin; 0.22, 0.39, and 0.77 µg/L for fC₆₀-bifenthrin mix; 6.63, 9.89, and 5.79 µg/L for tribufos; and 9.17, 8.17, and 6.59 µg/L for fC₆₀-tribufos mix. Mixtures did not affect instantaneous growth rate (p > 0.05). These results suggest that fC₆₀ had little effect on pesticide chronic toxicity but influenced acute toxicity. Given the widespread application of nanotechnology, the influence of nanomaterials on environmental contaminants is an important consideration. Thus, our results may be useful in the development and use of nanotechnology in agricultural practices. © 2010 SETAC.

  17. Abnormal lung function in adults with congenital heart disease: prevalence, relation to cardiac anatomy, and association with survival.

    Science.gov (United States)

    Alonso-Gonzalez, Rafael; Borgia, Francesco; Diller, Gerhard-Paul; Inuzuka, Ryo; Kempny, Aleksander; Martinez-Naharro, Ana; Tutarel, Oktay; Marino, Philip; Wustmann, Kerstin; Charalambides, Menelaos; Silva, Margarida; Swan, Lorna; Dimopoulos, Konstantinos; Gatzoulis, Michael A

    2013-02-26

    Restrictive lung defects are associated with higher mortality in patients with acquired chronic heart failure. We investigated the prevalence of abnormal lung function, its relation to severity of underlying cardiac defect, its surgical history, and its impact on outcome across the spectrum of adult congenital heart disease. A total of 1188 patients with adult congenital heart disease (age, 33.1±13.1 years) undergoing lung function testing between 2000 and 2009 were included. Patients were classified according to the severity of lung dysfunction based on predicted values of forced vital capacity. Lung function was normal in 53% of patients with adult congenital heart disease, mildly impaired in 17%, and moderately to severely impaired in the remainder (30%). Moderate to severe impairment of lung function related to complexity of underlying cardiac defect, enlarged cardiothoracic ratio, previous thoracotomy/ies, body mass index, scoliosis, and diaphragm palsy. Over a median follow-up period of 6.7 years, 106 patients died. Moderate to severe impairment of lung function was an independent predictor of survival in this cohort. Patients with reduced force vital capacity of at least moderate severity had a 1.6-fold increased risk of death compared with patients with normal lung function (P=0.04). A reduced forced vital capacity is prevalent in patients with adult congenital heart disease; its severity relates to the complexity of the underlying heart defect, surgical history, and scoliosis. Moderate to severe impairment of lung function is an independent predictor of mortality in contemporary patients with adult congenital heart disease.

  18. Cancer rehabilitation: a barometer for survival?

    Science.gov (United States)

    Saotome, Takako; Klein, Linda; Faux, Steven

    2015-10-01

    This pilot study was conducted to describe the clinical features and functional outcomes of patients attending inpatient rehabilitation for cancer-related deconditioning and neurological deficits and to explore factors associated with improved survival. Using a retrospective audit, demographic characteristics, discharge outcomes, survival time, and functional status as measured by Functional Independence Measure (FIM) were recorded for 73 patients. Clinical status was estimated by Karnofsky Performance Status Scale (KPS). Cox regression was used to assess factors associated with improved survival following discharge from rehabilitation. Significant functional gains following rehabilitation were observed in total FIM (p = 0.02), motor FIM (p = 0.001), and KPS (p = 0.003). Length of survival ranged from 9.0 to 25.0 months, with 26 cases surviving to the end of study (censored). Patients scoring a total FIM of ≥80 survived significantly longer than patients scoring <80 (p = 0.002). At discharge, motor FIM scores (p = 0.004), FIM Efficiency (p = 0.001), KPS scores (p = 0.022), ambulation ability (p = 0.026), return to home (p = 0.009), and receipt of in-home services (p = 0.045) were significantly associated with improved survival. Functional improvement achieved through inpatient rehabilitation was associated with prolonged survival among cancer patients. Rehabilitation leading to improved independence among cancer patients may act as a marker of those with greater likelihood of better prognosis.

  19. Combining parametric, semi-parametric, and non-parametric survival models with stacked survival models.

    Science.gov (United States)

    Wey, Andrew; Connett, John; Rudser, Kyle

    2015-07-01

    For estimating conditional survival functions, non-parametric estimators can be preferred to parametric and semi-parametric estimators due to relaxed assumptions that enable robust estimation. Yet, even when misspecified, parametric and semi-parametric estimators can possess better operating characteristics in small sample sizes due to smaller variance than non-parametric estimators. Fundamentally, this is a bias-variance trade-off situation in that the sample size is not large enough to take advantage of the low bias of non-parametric estimation. Stacked survival models estimate an optimally weighted combination of models that can span parametric, semi-parametric, and non-parametric models by minimizing prediction error. An extensive simulation study demonstrates that stacked survival models consistently perform well across a wide range of scenarios by adaptively balancing the strengths and weaknesses of individual candidate survival models. In addition, stacked survival models perform as well as or better than the model selected through cross-validation. Finally, stacked survival models are applied to a well-known German breast cancer study. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Upregulation of TrkB by forskolin facilitated survival of MSC and functional recovery of memory deficient model rats.

    Science.gov (United States)

    Heo, Hwon; Yoo, Minjoo; Han, Donghoon; Cho, Yakdol; Joung, Insil; Kwon, Yunhee Kim

    2013-02-22

    Mesenchymal stem cells (MSCs) are effective vectors in delivering a gene of interest into degenerating brain. In ex vivo gene therapy, viability of transplanted MSCs is correlated with the extent of functional recovery. It has been reported that BDNF facilitates survival of MSCs but dividing MSCs do not express the BDNF receptor, TrkB. In this study, we found that the expression of TrkB is upregulated in human MSCs by the addition of forskolin (Fsk), an activator of adenylyl cyclase. To increase survival rate of MSCs and their secretion of tropic factors that enhance regeneration of endogenous cells, we pre-exposed hMSCs with Fsk and transduced with BDNF-adenovirus before transplantation into the brain of memory deficient rats, a degenerating brain disease model induced by ibotenic acid injection. Viability of MSCs and expression of a GABA synthesizing enzyme were increased. The pre-treatment improved learning and memory, as detected by the behavioral tests including Y-maze task and passive avoidance test. These results suggest that TrkB expression of hMSCs elevates the neuronal regeneration and efficiency of BDNF delivery for treating degenerative neurological diseases accompanying memory loss. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Entropy Estimation of Disaggregate Production Functions: An Application to Northern Mexico

    Directory of Open Access Journals (Sweden)

    Richard E. Howitt

    2014-03-01

    Full Text Available This paper demonstrates a robust maximum entropy approach to estimating flexible-form farm-level multi-input/multi-output production functions using minimally specified disaggregated data. Since our goal is to address policy questions, we emphasize the model’s ability to reproduce characteristics of the existing production system and predict outcomes of policy changes at a disaggregate level. Measurement of distributional impacts of policy changes requires use of farm-level models estimated across a wide spectrum of sizes and types, which is often difficult with traditional econometric methods due to data limitations. We use a two-stage approach to generate observation-specific shadow values for incompletely priced inputs. We then use the shadow values and nominal input prices to estimate crop-specific production functions using generalized maximum entropy (GME to capture individual heterogeneity of the production environment while replicating observed inputs and outputs to production. The two-stage GME approach can be implemented with small data sets. We demonstrate this methodology in an empirical application to a small cross-section data set for Northern Rio Bravo, Mexico and estimate production functions for small family farms and moderate commercial farms. The estimates show considerable distributional differences resulting from policies that change water subsidies in the region or shift price supports to direct payments.

  2. A de-noising method using the improved wavelet threshold function based on noise variance estimation

    Science.gov (United States)

    Liu, Hui; Wang, Weida; Xiang, Changle; Han, Lijin; Nie, Haizhao

    2018-01-01

    The precise and efficient noise variance estimation is very important for the processing of all kinds of signals while using the wavelet transform to analyze signals and extract signal features. In view of the problem that the accuracy of traditional noise variance estimation is greatly affected by the fluctuation of noise values, this study puts forward the strategy of using the two-state Gaussian mixture model to classify the high-frequency wavelet coefficients in the minimum scale, which takes both the efficiency and accuracy into account. According to the noise variance estimation, a novel improved wavelet threshold function is proposed by combining the advantages of hard and soft threshold functions, and on the basis of the noise variance estimation algorithm and the improved wavelet threshold function, the research puts forth a novel wavelet threshold de-noising method. The method is tested and validated using random signals and bench test data of an electro-mechanical transmission system. The test results indicate that the wavelet threshold de-noising method based on the noise variance estimation shows preferable performance in processing the testing signals of the electro-mechanical transmission system: it can effectively eliminate the interference of transient signals including voltage, current, and oil pressure and maintain the dynamic characteristics of the signals favorably.

  3. Statistical computation of Boltzmann entropy and estimation of the optimal probability density function from statistical sample

    Science.gov (United States)

    Sui, Ning; Li, Min; He, Ping

    2014-12-01

    In this work, we investigate the statistical computation of the Boltzmann entropy of statistical samples. For this purpose, we use both histogram and kernel function to estimate the probability density function of statistical samples. We find that, due to coarse-graining, the entropy is a monotonic increasing function of the bin width for histogram or bandwidth for kernel estimation, which seems to be difficult to select an optimal bin width/bandwidth for computing the entropy. Fortunately, we notice that there exists a minimum of the first derivative of entropy for both histogram and kernel estimation, and this minimum point of the first derivative asymptotically points to the optimal bin width or bandwidth. We have verified these findings by large amounts of numerical experiments. Hence, we suggest that the minimum of the first derivative of entropy be used as a selector for the optimal bin width or bandwidth of density estimation. Moreover, the optimal bandwidth selected by the minimum of the first derivative of entropy is purely data-based, independent of the unknown underlying probability density distribution, which is obviously superior to the existing estimators. Our results are not restricted to one-dimensional, but can also be extended to multivariate cases. It should be emphasized, however, that we do not provide a robust mathematical proof of these findings, and we leave these issues with those who are interested in them.

  4. Density functionals for surface science: Exchange-correlation model development with Bayesian error estimation

    Science.gov (United States)

    Wellendorff, Jess; Lundgaard, Keld T.; Møgelhøj, Andreas; Petzold, Vivien; Landis, David D.; Nørskov, Jens K.; Bligaard, Thomas; Jacobsen, Karsten W.

    2012-06-01

    A methodology for semiempirical density functional optimization, using regularization and cross-validation methods from machine learning, is developed. We demonstrate that such methods enable well-behaved exchange-correlation approximations in very flexible model spaces, thus avoiding the overfitting found when standard least-squares methods are applied to high-order polynomial expansions. A general-purpose density functional for surface science and catalysis studies should accurately describe bond breaking and formation in chemistry, solid state physics, and surface chemistry, and should preferably also include van der Waals dispersion interactions. Such a functional necessarily compromises between describing fundamentally different types of interactions, making transferability of the density functional approximation a key issue. We investigate this trade-off between describing the energetics of intramolecular and intermolecular, bulk solid, and surface chemical bonding, and the developed optimization method explicitly handles making the compromise based on the directions in model space favored by different materials properties. The approach is applied to designing the Bayesian error estimation functional with van der Waals correlation (BEEF-vdW), a semilocal approximation with an additional nonlocal correlation term. Furthermore, an ensemble of functionals around BEEF-vdW comes out naturally, offering an estimate of the computational error. An extensive assessment on a range of data sets validates the applicability of BEEF-vdW to studies in chemistry and condensed matter physics. Applications of the approximation and its Bayesian ensemble error estimate to two intricate surface science problems support this.

  5. Modulating Function-Based Method for Parameter and Source Estimation of Partial Differential Equations

    KAUST Repository

    Asiri, Sharefa M.

    2017-10-08

    Partial Differential Equations (PDEs) are commonly used to model complex systems that arise for example in biology, engineering, chemistry, and elsewhere. The parameters (or coefficients) and the source of PDE models are often unknown and are estimated from available measurements. Despite its importance, solving the estimation problem is mathematically and numerically challenging and especially when the measurements are corrupted by noise, which is often the case. Various methods have been proposed to solve estimation problems in PDEs which can be classified into optimization methods and recursive methods. The optimization methods are usually heavy computationally, especially when the number of unknowns is large. In addition, they are sensitive to the initial guess and stop condition, and they suffer from the lack of robustness to noise. Recursive methods, such as observer-based approaches, are limited by their dependence on some structural properties such as observability and identifiability which might be lost when approximating the PDE numerically. Moreover, most of these methods provide asymptotic estimates which might not be useful for control applications for example. An alternative non-asymptotic approach with less computational burden has been proposed in engineering fields based on the so-called modulating functions. In this dissertation, we propose to mathematically and numerically analyze the modulating functions based approaches. We also propose to extend these approaches to different situations. The contributions of this thesis are as follows. (i) Provide a mathematical analysis of the modulating function-based method (MFBM) which includes: its well-posedness, statistical properties, and estimation errors. (ii) Provide a numerical analysis of the MFBM through some estimation problems, and study the sensitivity of the method to the modulating functions\\' parameters. (iii) Propose an effective algorithm for selecting the method\\'s design parameters

  6. Econometric estimation of the “Constant Elasticity of Substitution" function in R

    DEFF Research Database (Denmark)

    Henningsen, Arne; Henningsen, Geraldine

    The Constant Elasticity of Substitution (CES) function is popular in several areas of economics, but it is rarely used in econometric analysis because it cannot be estimated by standard linear regression techniques. We discuss several existing approaches and propose a new grid-search approach...

  7. Estimation of non-linear growth models by linearization: a simulation study using a Gompertz function.

    Science.gov (United States)

    Vuori, Kaarina; Strandén, Ismo; Sevón-Aimonen, Marja-Liisa; Mäntysaari, Esa A

    2006-01-01

    A method based on Taylor series expansion for estimation of location parameters and variance components of non-linear mixed effects models was considered. An attractive property of the method is the opportunity for an easily implemented algorithm. Estimation of non-linear mixed effects models can be done by common methods for linear mixed effects models, and thus existing programs can be used after small modifications. The applicability of this algorithm in animal breeding was studied with simulation using a Gompertz function growth model in pigs. Two growth data sets were analyzed: a full set containing observations from the entire growing period, and a truncated time trajectory set containing animals slaughtered prematurely, which is common in pig breeding. The results from the 50 simulation replicates with full data set indicate that the linearization approach was capable of estimating the original parameters satisfactorily. However, estimation of the parameters related to adult weight becomes unstable in the case of a truncated data set.

  8. Cognitive Function, Progression of Age-related Behavioral Changes, Biomarkers, and Survival in Dogs More Than 8 Years Old

    DEFF Research Database (Denmark)

    Schütt, T.; Berendt, M.; Toft, Nils

    2015-01-01

    patted, difficulty finding dropped food and anxiety. Thirty-three percent of dogs with a normal cognitive status progressed to MCI and 22% classified as MCI progressed to CCD during the study period. For 6 dogs diagnosed with CCD, signs of cognitive dysfunction increased with time. A diagnosis of CCD did......BackgroundCanine cognitive dysfunction (CCD) is an age-dependent neurodegenerative condition dominated by changes in behavioral patterns. Cohort studies investigating cognitive status in dogs are lacking. ObjectivesTo investigate cognitive function, progression of age-related behavioral changes......, survival, and possible biomarkers of CCD in aged dogs. AnimalsFifty-one dogs >8 years old; 21 with no cognitive deficits, 17 with mild cognitive impairments (MCI) and 13 with CCD. MethodsLongitudinal study. Recruitment period of 12 months and an observational period of 24 months including a baseline and 3...

  9. Basis Functions for Data Assimilative Estimation of Ionosphere and Thermosphere States Across the Globe

    Science.gov (United States)

    Miladinovich, D.; Datta-Barua, S.; Bust, G. S.; Makela, J. J.

    2016-12-01

    Understanding physical processes during storm time in the ionosphere-thermosphere (IT) system has been limited, in part, due to the inability to obtain accurate estimates of storm time states on a global scale. One reason for this inability is the insufficient quantity of spatially distributed high quality data sets. Data assimilation is showing promise toward enabling global estimates by blending limited data sets with established climate models. A data assimilation algorithm intended for ingesting globally distributed data sets requires its solution to be continuous and smooth. The algorithm Estimating Model Parameters for Ionospheric Reverse Engineering (EMPIRE) is a data assimilation algorithm that uses a Kalman filtering routine to ingest model and observational data. It has provided estimates of thermospheric neutral winds, ionospheric drifts and Earth's electric potential in localized mid-latitude regions. In this work we modify EMPIRE with an algorithm suitable for globally distributed data sets. Spherical harmonics in latitude and longitude provide a spherically symmetric, smooth, continuous, and orthonormal set of basis functions suitable for a spherical domain such as Earth's IT region (200-600 km altitude). Once the basis function coefficients are determined, the estimated function describes disagreement between observational measurements and models. We examine a case by applying spherical harmonics to study the southeastern U.S. region during the October 24-25th 2011 storm. Data sources include Fabry-Perot Interferometer neutral wind measurements and global Ionospheric Data Assimilation 4 Dimensional (IDA4D) assimilated total electron content (TEC). Models include Weimer 2000 electric potential, International Geomagnetic Reference Field (IGRF) magnetic field, and Horizontal Wind Model 2014 (HWM14) neutral winds. We compare the assimilation result using spherical harmonics to previous results that used power series basis functions. The analysis from

  10. PINK1 is necessary for long term survival and mitochondrial function in human dopaminergic neurons.

    Directory of Open Access Journals (Sweden)

    Alison Wood-Kaczmar

    2008-06-01

    Full Text Available Parkinson's disease (PD is a common age-related neurodegenerative disease and it is critical to develop models which recapitulate the pathogenic process including the effect of the ageing process. Although the pathogenesis of sporadic PD is unknown, the identification of the mendelian genetic factor PINK1 has provided new mechanistic insights. In order to investigate the role of PINK1 in Parkinson's disease, we studied PINK1 loss of function in human and primary mouse neurons. Using RNAi, we created stable PINK1 knockdown in human dopaminergic neurons differentiated from foetal ventral mesencephalon stem cells, as well as in an immortalised human neuroblastoma cell line. We sought to validate our findings in primary neurons derived from a transgenic PINK1 knockout mouse. For the first time we demonstrate an age dependent neurodegenerative phenotype in human and mouse neurons. PINK1 deficiency leads to reduced long-term viability in human neurons, which die via the mitochondrial apoptosis pathway. Human neurons lacking PINK1 demonstrate features of marked oxidative stress with widespread mitochondrial dysfunction and abnormal mitochondrial morphology. We report that PINK1 plays a neuroprotective role in the mitochondria of mammalian neurons, especially against stress such as staurosporine. In addition we provide evidence that cellular compensatory mechanisms such as mitochondrial biogenesis and upregulation of lysosomal degradation pathways occur in PINK1 deficiency. The phenotypic effects of PINK1 loss-of-function described here in mammalian neurons provides mechanistic insight into the age-related degeneration of nigral dopaminergic neurons seen in PD.

  11. Pancreatic Islet Survival and Engraftment Is Promoted by Culture on Functionalized Spider Silk Matrices.

    Science.gov (United States)

    Johansson, Ulrika; Ria, Massimiliano; Åvall, Karin; Dekki Shalaly, Nancy; Zaitsev, Sergei V; Berggren, Per-Olof; Hedhammar, My

    2015-01-01

    Transplantation of pancreatic islets is one approach for treatment of diabetes, however, hampered by the low availability of viable islets. Islet isolation leads to disruption of the environment surrounding the endocrine cells, which contributes to eventual cell death. The reestablishment of this environment is vital, why we herein investigated the possibility of using recombinant spider silk to support islets in vitro after isolation. The spider silk protein 4RepCT was formulated into three different formats; 2D-film, fiber mesh and 3D-foam, in order to provide a matrix that can give the islets physical support in vitro. Moreover, cell-binding motifs from laminin were incorporated into the silk protein in order to create matrices that mimic the natural cell environment. Pancreatic mouse islets were thoroughly analyzed for adherence, necrosis and function after in vitro maintenance on the silk matrices. To investigate their suitability for transplantation, we utilized an eye model which allows in vivo imaging of engraftment. Interestingly, islets that had been maintained on silk foam during in vitro culture showed improved revascularization. This coincided with the observation of preserved islet architecture with endothelial cells present after in vitro culture on silk foam. Selected matrices were further evaluated for long-term preservation of human islets. Matrices with the cell-binding motif RGD improved human islet maintenance (from 36% to 79%) with preserved islets architecture and function for over 3 months in vitro. The islets established cell-matrix contacts and formed vessel-like structures along the silk. Moreover, RGD matrices promoted formation of new, insulin-positive islet-like clusters that were connected to the original islets via endothelial cells. On silk matrices with islets from younger donors (<35 year), the amount of newly formed islet-like clusters found after 1 month in culture were almost double compared to the initial number of islets

  12. Pancreatic Islet Survival and Engraftment Is Promoted by Culture on Functionalized Spider Silk Matrices

    Science.gov (United States)

    Johansson, Ulrika; Dekki Shalaly, Nancy; Zaitsev, Sergei V.; Berggren, Per-Olof; Hedhammar, My

    2015-01-01

    Transplantation of pancreatic islets is one approach for treatment of diabetes, however, hampered by the low availability of viable islets. Islet isolation leads to disruption of the environment surrounding the endocrine cells, which contributes to eventual cell death. The reestablishment of this environment is vital, why we herein investigated the possibility of using recombinant spider silk to support islets in vitro after isolation. The spider silk protein 4RepCT was formulated into three different formats; 2D-film, fiber mesh and 3D-foam, in order to provide a matrix that can give the islets physical support in vitro. Moreover, cell-binding motifs from laminin were incorporated into the silk protein in order to create matrices that mimic the natural cell environment. Pancreatic mouse islets were thoroughly analyzed for adherence, necrosis and function after in vitro maintenance on the silk matrices. To investigate their suitability for transplantation, we utilized an eye model which allows in vivo imaging of engraftment. Interestingly, islets that had been maintained on silk foam during in vitro culture showed improved revascularization. This coincided with the observation of preserved islet architecture with endothelial cells present after in vitro culture on silk foam. Selected matrices were further evaluated for long-term preservation of human islets. Matrices with the cell-binding motif RGD improved human islet maintenance (from 36% to 79%) with preserved islets architecture and function for over 3 months in vitro. The islets established cell-matrix contacts and formed vessel-like structures along the silk. Moreover, RGD matrices promoted formation of new, insulin-positive islet-like clusters that were connected to the original islets via endothelial cells. On silk matrices with islets from younger donors (<35 year), the amount of newly formed islet-like clusters found after 1 month in culture were almost double compared to the initial number of islets

  13. A modified weighted function method for parameter estimation of Pearson type three distribution

    Science.gov (United States)

    Liang, Zhongmin; Hu, Yiming; Li, Binquan; Yu, Zhongbo

    2014-04-01

    In this paper, an unconventional method called Modified Weighted Function (MWF) is presented for the conventional moment estimation of a probability distribution function. The aim of MWF is to estimate the coefficient of variation (CV) and coefficient of skewness (CS) from the original higher moment computations to the first-order moment calculations. The estimators for CV and CS of Pearson type three distribution function (PE3) were derived by weighting the moments of the distribution with two weight functions, which were constructed by combining two negative exponential-type functions. The selection of these weight functions was based on two considerations: (1) to relate weight functions to sample size in order to reflect the relationship between the quantity of sample information and the role of weight function and (2) to allocate more weights to data close to medium-tail positions in a sample series ranked in an ascending order. A Monte-Carlo experiment was conducted to simulate a large number of samples upon which statistical properties of MWF were investigated. For the PE3 parent distribution, results of MWF were compared to those of the original Weighted Function (WF) and Linear Moments (L-M). The results indicate that MWF was superior to WF and slightly better than L-M, in terms of statistical unbiasness and effectiveness. In addition, the robustness of MWF, WF, and L-M were compared by designing the Monte-Carlo experiment that samples are obtained from Log-Pearson type three distribution (LPE3), three parameter Log-Normal distribution (LN3), and Generalized Extreme Value distribution (GEV), respectively, but all used as samples from the PE3 distribution. The results show that in terms of statistical unbiasness, no one method possesses the absolutely overwhelming advantage among MWF, WF, and L-M, while in terms of statistical effectiveness, the MWF is superior to WF and L-M.

  14. Neonatal line as a linear evidence of live birth: Estimation of postnatal survival of a new born from primary tooth germs.

    Science.gov (United States)

    Janardhanan, Mahija; Umadethan, B; Biniraj, Kr; Kumar, Rb Vinod; Rakesh, S

    2011-01-01

    The presence of neonatal line indicates live birth and it is possible to estimate the exact period of survival of the infant in days by measuring the amount of postnatal hard tissue formation, and thus can be an evidence to the brutal act of infanticide. Primary tooth germs of both the arches were removed from the sockets of an infant who died few days after birth. Ground sections were made with hard tissue microtome. Decalcified sections were made from the crown of primary right mandibular canine and the sections were stained with hematoxylin and eosin. To visualize the neonatal line, the sections were subjected to light mocroscopy, polarized microscopy and scanning electron microscopy. A developing permanent molar from a one and a half year old boy and ten fully developed deciduous molars were used as controls. The ground sections of all the developing tooth germs showed the presence of neonatal line and the analysis of enamel showed six distinct cross striations along the enamel rod length indicating the period of survival of the baby to be six days which was later confirmed with the hospital records. Neonatal line could be used as an evidence of infanticide. Accurate detection of neonatal line with advanced techniques could rewrite this supplementary evidence of infanticide into substantial evidence.

  15. Modulating functions method for parameters estimation in the fifth order KdV equation

    KAUST Repository

    Asiri, Sharefa M.

    2017-07-25

    In this work, the modulating functions method is proposed for estimating coefficients in higher-order nonlinear partial differential equation which is the fifth order Kortewegde Vries (KdV) equation. The proposed method transforms the problem into a system of linear algebraic equations of the unknowns. The statistical properties of the modulating functions solution are described in this paper. In addition, guidelines for choosing the number of modulating functions, which is an important design parameter, are provided. The effectiveness and robustness of the proposed method are shown through numerical simulations in both noise-free and noisy cases.

  16. Timing of therapeutic intervention determines functional and survival outcomes in a mouse model of late infantile batten disease.

    Science.gov (United States)

    Cabrera-Salazar, Mario A; Roskelley, Eric M; Bu, Jie; Hodges, Bradley L; Yew, Nelson; Dodge, James C; Shihabuddin, Lamya S; Sohar, Istvan; Sleat, David E; Scheule, Ronald K; Davidson, Beverly L; Cheng, Seng H; Lobel, Peter; Passini, Marco A

    2007-10-01

    Classical late infantile neuronal ceroid lipofuscinosis (cLINCL) is a monogenic disorder caused by the loss of tripeptidyl peptidase 1 (TPP1) activity as a result of mutations in CLN2. Absence of TPP1 results in lysosomal storage with an accompanying axonal degeneration throughout the central nervous system (CNS), which leads to progressive neurodegeneration and early death. In this study, we compared the efficacies of pre- and post-symptomatic injections of recombinant adeno-associated virus (AAV) for treating the cellular and functional abnormalities of CLN2 mutant mice. Intracranial injection of AAV1-hCLN2 resulted in widespread human TPP1 (hTPP1) activity in the brain that was 10-100-fold above wild-type levels. Injections before disease onset prevented storage and spared neurons from axonal degeneration, reflected by the preservation of motor function. Furthermore, the majority of CLN2 mutant mice treated pre-symptomatically lived for at least 330 days, compared with a median survival of 151 days in untreated CLN2 mutant controls. In contrast, although injection after disease onset ameliorated lysosomal storage, there was evidence of axonal degeneration, motor function showed limited recovery, and the animals had a median lifespan of 216 days. These data illustrate the importance of early intervention for enhanced therapeutic benefit, which may provide guidance in designing novel treatment strategies for cLINCL patients.

  17. Cerebellar asymmetry and its relation to cerebral asymmetry estimated by intrinsic functional connectivity

    Science.gov (United States)

    Wang, Danhong; Buckner, Randy L.

    2013-01-01

    Asymmetry of the human cerebellum was investigated using intrinsic functional connectivity. Regions of functional asymmetry within the cerebellum were identified during resting-state functional MRI (n = 500 subjects) and replicated in an independent cohort (n = 500 subjects). The most strongly right lateralized cerebellar regions fell within the posterior lobe, including crus I and crus II, in regions estimated to link to the cerebral association cortex. The most strongly left lateralized cerebellar regions were located in lobules VI and VIII in regions linked to distinct cerebral association networks. Comparison of cerebellar asymmetry with independently estimated cerebral asymmetry revealed that the lateralized regions of the cerebellum belong to the same networks that are strongly lateralized in the cerebrum. The degree of functional asymmetry of the cerebellum across individuals was significantly correlated with cerebral asymmetry and varied with handedness. In addition, cerebellar asymmetry estimated at rest predicted cerebral lateralization during an active language task. These results demonstrate that functional lateralization is likely a unitary feature of large-scale cerebrocerebellar networks, consistent with the hypothesis that the cerebellum possesses a roughly homotopic map of the cerebral cortex including the prominent asymmetries of the association cortex. PMID:23076113

  18. Need for Estimating the Glomerular Filtration Rate to Assess Renal Function

    Directory of Open Access Journals (Sweden)

    José Antonio Chipi Cabrera

    2013-11-01

    Full Text Available Background: plasma creatinine alone is not useful for assessing renal function; patients with normal creatinine values can experience a significant decline in the glomerular filtration rate, hindering early detection of renal function impairment. Objective: to assess renal function by determining the plasma creatinine compared to the glomerular filtration rate estimated through the Cockcroft -Gault, MDRD -4 and CKD- Epi formulas. Methods: the database of a population-based epidemiological study conducted in the Isle of Youth since November 2004 was used. It involved 897 patients, 342 women and 555 men. Plasma creatinine and glomerular filtration rate were estimated by means of 3 formulas. Renal function was considered normal when serum creatinine values were <123 µmol/l for women and <132 µmol/l for men and glomerular filtration rate > 60 ml/min. Results: plasma creatinine was stable in the four age groups, with a mean of 100.68 ± 38.01, glomerular filtration rate decreased with increasing age in the three formulas. Correlation coefficient between plasma creatinine values and glomerular filtration rate for each formula expressed a linear relationship with r [CG formula 0.639 (p = 0.000], [0.672 MDRD -4 (p = 0.000] and [0.939 CKD – Epi formula (p = 0.000]. Conclusions: the utility of the methods for estimating the glomerular filtration rate was demonstrated, leading to the detection of the renal function impairment before the serum creatinine level increases.

  19. Correlation of neurocognitive function and brain parenchyma volumes in children surviving cancer

    Science.gov (United States)

    Reddick, Wilburn E.; White, Holly A.; Glass, John O.; Mulhern, Raymond K.

    2002-04-01

    This research builds on our hypothesis that white matter damage and associated neurocognitive symptoms, in children treated for cancer with cranial spinal irradiation, spans a continuum of severity that can be reliably probed using non-invasive MR technology. Quantitative volumetric assessments of MR imaging and psychological assessments were obtained in 40 long-term survivors of malignant brain tumors treated with cranial irradiation. Neurocognitive assessments included a test of intellect (Wechsler Intelligence Test for Children, Wechsler Adult Intelligence Scale), attention (Conner's Continuous Performance Test), and memory (California Verbal Learning Test). One-sample t-tests were conducted to evaluate test performance of survivors against age-adjusted scores from the test norms; these analyses revealed significant impairments in all apriori selected measures of intelligence, attention, and memory. Partial correlation analyses were performed to assess the relationships between brain tissues volumes (normal appearing white matter (NAWM), gray matter, and CSF) and neurocognitive function. Global intelligence (r = 0.32, p = 0.05) and global attentional (r = 0.49, p < 0.01) were significantly positively correlated with NAWM volumes, whereas global memory was significantly positively correlated with overall brain parenchyma (r = 0.38, p = 0.04). We conclude that quantitative assessment of MR examinations in survivors of childhood cancer treated with cranial irradiation reveal that loss of NAWM is associated with decreased intellectual and attentional deficits, whereas overall parenchyma loss, as reflected by increased CSF and decreased white matter, is associated with memory-related deficits.

  20. Methylenetetrahydrofolate reductase 677C>T and methionine synthase 2756A>G mutations: no impact on survival, cognitive functioning, or cognitive decline in nonagenarians

    DEFF Research Database (Denmark)

    Bathum, Lise; von Bornemann Hjelmborg, Jacob; Christiansen, Lene

    2007-01-01

    BACKGROUND: Several reports have shown an association between homocysteine, cognitive functioning, and survival among the oldest-old. Two common polymorphisms in the genes coding for methylenetetrahydrofolate reductase (MTHFR 677C>T) and methionine synthase (MTR 2756A>G) have an impact on plasma...... homocysteine level. METHODS: We examined the effect of the MTHFR 677C>T and MTR 2756A>G genotypes on baseline cognitive functioning, cognitive decline over 5 years measured in three assessments, and survival in a population-based cohort of 1581 nonagenarians. Cognitive functioning was assessed by using...

  1. Upper Limb Functionality and Quality of Life in Women with Five-Year Survival after Breast Cancer Surgery.

    Science.gov (United States)

    Recchia, Thaís Lunardi; Prim, Amably Cristiny; Luz, Clarissa Medeiros da

    2017-03-01

    Objective To evaluate the correlation between upper limb functionality and quality of life in women with five-year survival following breast cancer surgical treatment. The secondary objective was to evaluate the function of the ipsilateral upper limb and the quality of life in relation to the type of surgery and the presence of pain. Methods The Disabilities of Arm, Shoulder and Hand (DASH), and the Functional Assessment of Cancer Therapy - Breast plus Arm Morbidity (FACTB + 4) questionnaires were used to evaluate upper limb function and quality of life respectively. Data distribution was verified by the Shapiro-Wilk test. Pearson's correlation coefficient was used for the parametric variables, and Spearman's rank correlation coefficient was used for the distribution of non-parametric variables. The statistical significance was set at 5% (p < 0.05). Results The study included 30 patients, with a mean age of 51.23 (±8.72) years. The most common complications were: pain (50%), adherence (33.3%), and nerve lesion (20.0%). There was a moderate negative correlation between the instruments DASH and FACTB + 4 (total score), r = -0.634, and a strong negative correlation between the DASH and the FACTB + 4 arm subscale, r = -0.829. The scores of both questionnaires showed significant difference on the manifestation of pain. However, there was no significant difference found when comparing the scores considering the type of surgery performed. Conclusions Five years after surgery, the patients showed regular functionality levels on the ipsilateral upper limb and decreased quality of life, especially in the group manifesting pain. Thieme-Revinter Publicações Ltda Rio de Janeiro, Brazil.

  2. Estimation of the probability of bacterial population survival: Development of a probability model to describe the variability in time to inactivation of Salmonella enterica.

    Science.gov (United States)

    Koyama, Kento; Hokunan, Hidekazu; Hasegawa, Mayumi; Kawamura, Shuso; Koseki, Shigenobu

    2017-12-01

    Despite the development of numerous predictive microbial inactivation models, a model focusing on the variability in time to inactivation for a bacterial population has not been developed. Additionally, an appropriate estimation of the risk of there being any remaining bacterial survivors in foods after the application of an inactivation treatment has not yet been established. Here, Gamma distribution, as a representative probability distribution, was used to estimate the variability in time to inactivation for a bacterial population. Salmonella enterica serotype Typhimurium was evaluated for survival in a low relative humidity environment. We prepared bacterial cells with an initial concentration that was adjusted to 2 × 10n colony-forming units/2 μl (n = 1, 2, 3, 4, 5) by performing a serial 10-fold dilution, and then we placed 2 μl of the inocula into each well of 96-well microplates. The microplates were stored in a desiccated environment at 10-20% relative humidity at 5, 15, or 25 °C. The survival or death of bacterial cells for each well in the 96-well microplate was confirmed by adding tryptic soy broth as an enrichment culture. The changes in the death probability of the 96 replicated bacterial populations were described as a cumulative Gamma distribution. The variability in time to inactivation was described by transforming the cumulative Gamma distribution into a Gamma distribution. We further examined the bacterial inactivation on almond kernels and radish sprout seeds. Additionally, we described certainty levels of bacterial inactivation that ensure the death probability of a bacterial population at six decimal reduction levels, ranging from 90 to 99.9999%. Consequently, the probability model developed in the present study enables us to estimate the death probability of bacterial populations in a desiccated environment over time. This probability model may be useful for risk assessment to estimate the amount of remaining bacteria in a given

  3. Heritability of pulmonary function estimated from genome-wide SNPs in healthy Japanese adults.

    Science.gov (United States)

    Yamada, Hideyasu; Yatagai, Yohei; Masuko, Hironori; Sakamoto, Tohru; Iijima, Hiroaki; Naito, Takashi; Noguchi, Emiko; Hirota, Tomomitsu; Tamari, Mayumi; Hizawa, Nobuyuki

    2015-03-01

    Pulmonary function is a heritable trait, and recent genome-wide association studies (GWASs) have identified a number of loci influencing the trait. Genome-wide Complex Trait Analysis (GCTA) is a novel method provided by a software package that estimates the total additive genetic influence caused by common single nucleotide polymorphisms (SNPs) on whole-genome arrays. We conducted a GWAS and assessed the heritability of pulmonary function in an adult Japanese population using this approach. We initially conducted a GWAS on %forced vital capacity (FVC), %forced expiratory volume (FEV1) and FEV1/FVC in healthy Japanese adults (N=967). We then examined the heritability of these traits using GCTA with a total of 480,026 SNPs. We also estimated the genetic impact of the 24 genes identified as susceptibility genes to FEV1/FVC in six previous GWASs on the heritability of FEV1/FVC in the Japanese population. The heritabilities for %FVC, %FEV1, and FEV1/FVC were 71.2%, 51.9% and 41.6%, respectively. These results corresponded to previous heritability estimates for pulmonary function obtained by GCTA or by twin studies. The 24 previously reported pulmonary function genes accounted for 4.3-12.0% of the entire estimated heritability of FEV1/FVC. This study demonstrated that the heritability of pulmonary function traits can be explained by the additive effects of multiple common SNPs in healthy Japanese adults. The pulmonary function genes reported in previous GWASs of non-Japanese populations showed a definite impact of the genes on FEV1/FVC, thus indicating the presence of common pathways related to this trait beyond ethnicity. Copyright © 2014 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

  4. Increased actin polymerization and stabilization interferes with neuronal function and survival in the AMPKγ mutant Loechrig.

    Directory of Open Access Journals (Sweden)

    Mandy Cook

    Full Text Available loechrig (loe mutant flies are characterized by progressive neuronal degeneration, behavioral deficits, and early death. The mutation is due to a P-element insertion in the gene for the γ-subunit of the trimeric AMP-activated protein kinase (AMPK complex, whereby the insertion affects only one of several alternative transcripts encoding a unique neuronal isoform. AMPK is a cellular energy sensor that regulates a plethora of signaling pathways, including cholesterol and isoprenoid synthesis via its downstream target hydroxy-methylglutaryl (HMG-CoA reductase. We recently showed that loe interferes with isoprenoid synthesis and increases the prenylation and thereby activation of RhoA. During development, RhoA plays an important role in neuronal outgrowth by activating a signaling cascade that regulates actin dynamics. Here we show that the effect of loe/AMPKγ on RhoA prenylation leads to a hyperactivation of this signaling pathway, causing increased phosphorylation of the actin depolymerizating factor cofilin and accumulation of filamentous actin. Furthermore, our results show that the resulting cytoskeletal changes in loe interfere with neuronal growth and disrupt axonal integrity. Surprisingly, these phenotypes were enhanced by expressing the Slingshot (SSH phosphatase, which during development promotes actin depolymerization by dephosphorylating cofilin. However, our studies suggest that in the adult SSH promotes actin polymerization, supporting in vitro studies using human SSH1 that suggested that SSH can also stabilize and bundle filamentous actin. Together with the observed increase in SSH levels in the loe mutant, our experiments suggest that in mature neurons SSH may function as a stabilization factor for filamentous actin instead of promoting actin depolymerization.

  5. Effects of GDNF pretreatment on function and survival of transplanted fetal ventral mesencephalic cells in the 6-OHDA rat model of Parkinson's disease

    DEFF Research Database (Denmark)

    Andereggen, Lukas; Meyer, Morten; Guzman, Raphael

    2009-01-01

    Transplantation of fetal dopaminergic (DA) neurons offers an experimental therapy for Parkinson's disease (PD). The low availability and the poor survival and integration of transplanted cells in the host brain are major obstacles in this approach. Glial cell line-derived neurotrophic factor (GDN....... In sum, our findings demonstrate that GDNF pretreatment was not disadvantageous for transplants of embryonic rat VM with the FFRT culture technique but only marginally improved graft survival and function....

  6. Land-use change and carbon sinks: Econometric estimation of the carbon sequestration supply function

    Energy Technology Data Exchange (ETDEWEB)

    Lubowski, Ruben N.; Plantinga, Andrew J.; Stavins, Robert N.

    2001-01-01

    Increased attention by policy makers to the threat of global climate change has brought with it considerable interest in the possibility of encouraging the expansion of forest area as a means of sequestering carbon dioxide. The marginal costs of carbon sequestration or, equivalently, the carbon sequestration supply function will determine the ultimate effects and desirability of policies aimed at enhancing carbon uptake. In particular, marginal sequestration costs are the critical statistic for identifying a cost-effective policy mix to mitigate net carbon dioxide emissions. We develop a framework for conducting an econometric analysis of land use for the forty-eight contiguous United States and employing it to estimate the carbon sequestration supply function. By estimating the opportunity costs of land on the basis of econometric evidence of landowners' actual behavior, we aim to circumvent many of the shortcomings of previous sequestration cost assessments. By conducting the first nationwide econometric estimation of sequestration costs, endogenizing prices for land-based commodities, and estimating land-use transition probabilities in a framework that explicitly considers the range of land-use alternatives, we hope to provide better estimates eventually of the true costs of large-scale carbon sequestration efforts. In this way, we seek to add to understanding of the costs and potential of this strategy for addressing the threat of global climate change.

  7. Merging multiple longitudinal studies with study-specific missing covariates: A joint estimating function approach.

    Science.gov (United States)

    Wang, Fei; Song, Peter X-K; Wang, Lu

    2015-12-01

    Merging multiple datasets collected from studies with identical or similar scientific objectives is often undertaken in practice to increase statistical power. This article concerns the development of an effective statistical method that enables to merge multiple longitudinal datasets subject to various heterogeneous characteristics, such as different follow-up schedules and study-specific missing covariates (e.g., covariates observed in some studies but missing in other studies). The presence of study-specific missing covariates presents great statistical methodology challenge in data merging and analysis. We propose a joint estimating function approach to addressing this challenge, in which a novel nonparametric estimating function constructed via splines-based sieve approximation is utilized to bridge estimating equations from studies with missing covariates to those with fully observed covariates. Under mild regularity conditions, we show that the proposed estimator is consistent and asymptotically normal. We evaluate finite-sample performances of the proposed method through simulation studies. In comparison to the conventional multiple imputation approach, our method exhibits smaller estimation bias. We provide an illustrative data analysis using longitudinal cohorts collected in Mexico City to assess the effect of lead exposures on children's somatic growth. © 2015, The International Biometric Society.

  8. Estimating Survival in Melanoma Patients With Brain Metastases: An Update of the Graded Prognostic Assessment for Melanoma Using Molecular Markers (Melanoma-molGPA).

    Science.gov (United States)

    Sperduto, Paul W; Jiang, Wen; Brown, Paul D; Braunstein, Steve; Sneed, Penny; Wattson, Daniel A; Shih, Helen A; Bangdiwala, Ananta; Shanley, Ryan; Lockney, Natalie A; Beal, Kathryn; Lou, Emil; Amatruda, Thomas; Sperduto, William A; Kirkpatrick, John P; Yeh, Norman; Gaspar, Laurie E; Molitoris, Jason K; Masucci, Laura; Roberge, David; Yu, James; Chiang, Veronica; Mehta, Minesh

    2017-11-15

    To update the Diagnosis-Specific Graded Prognostic Assessment (DS-GPA) for a markedly heterogeneous patient population, patients with melanoma and brain metastases, using a larger, more current cohort, including molecular markers. The original Melanoma-GPA is based on data from 483 patients whose conditions were diagnosed between 1985 and 2005. This is a multi-institutional retrospective database analysis of 823 melanoma patients with newly diagnosed brain metastases from January 1, 2006, to December 31, 2015. Multivariable analyses identified significant prognostic factors, which were weighted and included in the updated index (Melanoma-molGPA). Multiple Cox regression was used to select and weight prognostic factors in proportion to their hazard ratios to design the updated Melanoma-molGPA in which scores of 4.0 and 0.0 are associated with the best and worst prognoses, as with all of the diagnosis-specific GPA indices. Log-rank tests were used to compare adjacent classes. There were 5 significant prognostic factors for survival (age, Karnofsky performance status [KPS], extracranial metastases [ECM], number of brain metastases, and BRAF status), whereas only KPS and the number of brain metastases were significant in the original Melanoma-GPA. Median survival improved from 6.7 to 9.8 months between the 2 treatment eras, and the median survival times for patients with Melanoma-molGPA of 0 to 1.0, 1.5 to 2.0, 2.5 to 3.0, and 3.5 to 4.0 were 4.9, 8.3, 15.8, and 34.1 months (Pmelanoma patients with brain metastases has improved significantly. The updated Melanoma-molGPA, a user-friendly tool to estimate survival, will facilitate clinical decision making regarding whether and which treatment is appropriate and will also be useful for stratification of future clinical trials. To further simplify use, a free online/smart phone app is available at brainmetgpa.com. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Design and Analysis of Salmonid Tagging Studies in the Columbia Basin : Evaluating Wetland Restoration Projects in the Columbia River Estuary using Hydroacoustic Telemetry Arrays to Estimate Movement, Survival, and Residence Times of Juvenile Salmonids, Volume XXII (22).

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Russell W.; Skalski, John R.

    2008-08-01

    Wetlands in the Columbia River estuary are actively being restored by reconnecting these habitats to the estuary, making more wetland habitats available to rearing and migrating juvenile salmon. Concurrently, thousands of acoustically tagged juvenile salmonids are released into the Columbia River to estimate their survival as they migrate through the estuary. Here, we develop a release-recapture model that makes use of these tagged fish to measure the success of wetland restoration projects in terms of their contribution to populations of juvenile salmon. Specifically, our model estimates the fraction of the population that enter the wetland, survival within the wetland, and the mean residence time of fish within the wetland. Furthermore, survival in mainstem Columbia River downstream of the wetland can be compared between fish that remained the mainstem and entered the wetland. These conditional survival estimates provide a means of testing whether the wetland improves the subsequent survival of juvenile salmon by fostering growth or improving their condition. Implementing such a study requires little additional cost because it takes advantage of fish already released to estimate survival through the estuary. Thus, such a study extracts the maximum information at minimum cost from research projects that typically cost millions of dollars annually.

  10. Diversity-interaction modeling: estimating contributions of species identities and interactions to ecosystem function

    DEFF Research Database (Denmark)

    Kirwan, L; Connolly, J; Finn, J A

    2009-01-01

    We develop a modeling framework that estimates the effects of species identity and diversity on ecosystem function and permits prediction of the diversity-function relationship across different types of community composition. Rather than just measure an overall effect of diversity, we separately...... to the roles of evenness, functional groups, and functional redundancy. These more parsimonious descriptions can be especially useful in identifying general diversity-function relationships in communities with large numbers of species. We provide an example of the application of the modeling framework....... These models describe community-level performance and thus do not require separate measurement of the performance of individual species. This flexible modeling approach can be tailored to test many hypotheses in biodiversity research and can suggest the interaction mechanisms that may be acting....

  11. Recovery of renal function and survival after continuous renal replacement therapy during extracorporeal membrane oxygenation.

    Science.gov (United States)

    Paden, Matthew L; Warshaw, Barry L; Heard, Micheal L; Fortenberry, James D

    2011-03-01

    To assess the outcome of pediatric patients supported by concomitant extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT). Acute kidney injury is associated with mortality in ECMO patients. CRRT in patients on ECMO provides an efficient and potentially beneficial method of acute kidney injury management. Concern that concomitant CRRT use increases the risk of developing anuria and chronic renal failure limits its use in some centers. We hypothesized that development of chronic renal failure is rare with concurrent ECMO and CRRT. We evaluated the outcomes of 154 ECMO/CRRT patients cared for over 10 yrs at a referral pediatric medical center. None. Among 68 (44%) ECMO/CRRT survivors, 45 were assigned a pediatric risk, injury, failure, loss and end-stage (referred to as "pRIFLE") score at CRRT initiation. Seventeen (38%) patients met the criteria for Risk, 15 (33%) for Injury, and 10 (22%) for Failure. Two Failure patients later met End stage criteria. Of all survivors, 18 (26%) required ongoing renal replacement therapy (15 required continuous veno-venous hemofiltration, two required peritoneal dialysis, and one patient required intermittent hemodialysis) post ECMO discontinuation. Renal recovery occurred in 65 (96%) of 68 patients before discharge. One neonatal patient had sepsis-induced renal injury on transfer, but had normal creatinine 1 month later. Two pediatric patients with vasculitis and primary renal disease at presentation (both meeting Failure criteria) developed end-stage renal disease. One received peritoneal dialysis and subsequent renal transplant. The other has diminished function without need for renal replacement therapy. In the absence of primary renal disease, chronic renal failure did not occur after concurrent use of CRRT with ECMO. Concern for precipitating chronic renal failure by using CRRT during ECMO is not substantiated by this large single-center experience. Consistent with previous reports

  12. Pulmonary Hypertension in Heart Failure. Epidemiology, Right Ventricular Function, and Survival.

    Science.gov (United States)

    Gerges, Mario; Gerges, Christian; Pistritto, Anna-Maria; Lang, Marie B; Trip, Pia; Jakowitsch, Johannes; Binder, Thomas; Lang, Irene M

    2015-11-15

    Patients with pulmonary hypertension due to left heart disease (PH-LHD) and a diastolic pulmonary vascular pressure gradient ≥ 7 mm Hg, representing PH out of proportion to pulmonary arterial wedge pressure, have pulmonary vascular disease and increased mortality. Little information exists on this condition, recently labeled as "combined pre- and post-capillary PH" (Cpc-PH). To investigate epidemiology, risk factors, right ventricular function, and outcomes in patients with chronic heart failure and Cpc-PH. The study population was identified from a retrospective chart review of a clinical database of 3,107 stable patients who underwent first diagnostic right heart catheterization and from a prospective cohort of 800 consecutive patients at a national university-affiliated tertiary center. The retrospective cohort had 664 patients with systolic heart failure (SHF) and 399 patients with diastolic heart failure (DHF), 12% of whom were classified as Cpc-PH. The prospective cohort had 172 patients with SHF (14% Cpc-PH) and 219 patients with DHF (12% Cpc-PH). Chronic obstructive pulmonary disease (P = 0.034) and the tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio (P = 0.015) predicted Cpc-PH in SHF. Younger age (P = 0.004), valvular heart disease (P = 0.046), and the tricuspid annular plane systolic excursion to systolic pulmonary artery pressure ratio predicted Cpc-PH in DHF (P = 0.016). Right ventricular-pulmonary vascular coupling was worse in Cpc-PH patients (end-systolic elastance to effective arterial elastance [Ees/Ea]: SHF: 1.05 ± 0.25; P = 0.002; DHF: 1.17 ± 0.27; P = 0.027) than in those with isolated post-capillary PH (Ees/Ea: SHF: 1.52 ± 0.51; DHF: 1.45 ± 0.29). Cpc-PH is rare in chronic heart failure. Right ventricular-pulmonary vascular coupling is poor in Cpc-PH and could be one explanation for dismal outcomes.

  13. Influence of heavy ions on cell survival, cytogenetic damage and mitochondrial function of human endothelial cells

    Science.gov (United States)

    Ritter, Sylvia; Helm, Alexander; Lee, Ryonfa; Pollet, Dieter; Durante, Marco

    There is increasing evidence that there is an elevated risk of cardiovascular disease among atomic bomb survivors and radiotherapy patients, typically developing with a long latency. However, essentially no information is available on the potential cardiovascular risks associated with space radiation, in particular heavy ions. To address this issue, we have chosen human umbilical vein endothelial cells (HUVEC) as a model system. Cells at an early passage number were irradiated with 0.1 to 4 Gy of either 9.8 MeV/u C-ions (LET=170 keV/µm), 91 MeV/u C-ions (LET=29 keV/µm) or 250 kV X-rays. Cells were regularly subcultured up to 40 days (20 population doublings) post-irradiation. Immediately after exposure cell inactivation was deter-mined by the colony forming assay. Furthermore, at selected time-points cytogenetic damage (formation of micronuclei in binucleated cells) and the mitochondrial membrane potential ΨM (flow cytometric analysis following JC-1 staining) were assessed. Measurement of the directly induced radiation damage showed that 9.8 MeV/u and 91 MeV/u C-ions were more effective than X-rays (i.e. about 3 and 2 times, respectively) with respect to cell inactivation or the in-duction of cytogenetic damage. At the subsequent days in the irradiated cultures the number of cells with micronuclei declined to the control level (3-5Altogether our data indicate that under the applied radiation conditions the integrity of mitochondria which play a significant role in the regulation of cardiovascular cell function is not impaired. With respect to directly induced genetic damage C-ions are more effective than X-rays as observed in other cell systems. If the effectiveness of charged particles for the occurrence of late chromosomal damage in endothelial cells is higher than that of sparsely ionizing radiation needs further clarification. The data obtained up to now indicate that sophisticated cytogenetic techniques have to be applied in order to draw any firm

  14. Cognitive Function, Progression of Age-related Behavioral Changes, Biomarkers, and Survival in Dogs More Than 8 Years Old.

    Science.gov (United States)

    Schütt, T; Toft, N; Berendt, M

    2015-01-01

    Canine cognitive dysfunction (CCD) is an age-dependent neurodegenerative condition dominated by changes in behavioral patterns. Cohort studies investigating cognitive status in dogs are lacking. To investigate cognitive function, progression of age-related behavioral changes, survival, and possible biomarkers of CCD in aged dogs. Fifty-one dogs >8 years old; 21 with no cognitive deficits, 17 with mild cognitive impairments (MCI) and 13 with CCD. Longitudinal study. Recruitment period of 12 months and an observational period of 24 months including a baseline and 3 planned subsequent assessments. Cognitive status was determined using validated questionnaires. Plasma Aβ-peptides were quantified using commercial ELISA assays and cytokines by a validated immunoassay. Signs characterizing dogs with CCD were aimless wandering, staring into space, avoid getting patted, difficulty finding dropped food and anxiety. Thirty-three percent of dogs with a normal cognitive status progressed to MCI and 22% classified as MCI progressed to CCD during the study period. For 6 dogs diagnosed with CCD, signs of cognitive dysfunction increased with time. A diagnosis of CCD did not affect survival. The level of plasma Aβ42 was significantly increased (P < .05) in the CCD group (92.8 ± 24.0 pg/mL) compared to the MCI (77.0 ± 12.3 pg/mL) and normal group (74.9 ± 10.0 pg/mL), but no significant differences in concentrations of systemic inflammatory markers were detected. Canine cognitive dysfunction is a progressive disorder with an individual variability in the rate of cognitive decline and clinical signs. Plasma Aβ42 seems to be an interesting plasma biomarker of CCD. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  15. Conditional inactivation of MRG15 gene function limits survival during larval and adult stages of Drosophila melanogaster.

    Science.gov (United States)

    Zhang, Hongjun; Li, Yishi; Yang, Junsheng; Tominaga, Kaoru; Pereira-Smith, Olivia M; Tower, John

    2010-11-01

    The mammalian MRG15 gene encodes a chromodomain protein predicted to bind to chromatin via methylated histone tails. Human MORF4 encodes a related but truncated protein that is capable of promoting cellular senescence in a subset of human tumor cell lines. Drosophila contains a single homolog of human MRG15, called DmMRG15. Null mutation of MRG15 is embryonic-lethal in mice and Drosophila, making the study of MRG15 requirements in adults difficult. In these studies the DmMRG15 gene was over-expressed in Drosophila, during developmental stages and in adults, using a doxycycline-regulated system (Tet-on). In addition an inverted-repeated construct was designed to inactivate DmMRG15 via the RNAi pathway, and RNAi constructs were expressed using both the Tet-on system and Geneswitch system. The DmMRG15 protein was readily expressed in adult flies in a doxycycline-dependent manner. A truncated form of DmMRG15 (called DmMT1) was designed to mimic the structure of human MORF4, and expression of this mutant protein or the inverted-repeat constructs inhibited fertility in females. Conditional expression of the DmMRG15 inverted-repeat constructs during larval development or in adults caused reductions in survival. These experiments indicate that Drosophila DmMRG15 gene function is required for female fertility, larval survival and adult life span, and provide reagents that should be useful for further dissecting the role of DmMRG15 in cell proliferation and aging. Copyright © 2010 Elsevier Inc. All rights reserved.

  16. CHARACTERIZATION OF MAMMARY GLAND TISSUE USING JOINT ESTIMATORS OF MINKOWSKI FUNCTIONALS

    Directory of Open Access Journals (Sweden)

    Torsten Mattfeldt

    2011-05-01

    Full Text Available A theoretical approach to estimate the Minkowski functionals, i.e., area fraction, specifc boundary length and specifc Euler number in 2D, and their asymptotic covariance matrix proposed by Spodarev and Schmidt (2005 and Pantle et al. (2006a;b is applied to real image data. These two-dimensional images show mammary gland tissue and should be classifed automatically as tumor-free or mammary cancer, respectively. The estimation procedure is illustrated step-by-step and the calculations are described in detail. To reduce dependencies from chosen parameters, a least-squares approach is considered as recommended by Klenk et al. (2006. Emphasis is placed on the detailed description of the estimation procedure and the application of the theory to real image data.

  17. Estimation of Multiple Point Sources for Linear Fractional Order Systems Using Modulating Functions

    KAUST Repository

    Belkhatir, Zehor

    2017-06-28

    This paper proposes an estimation algorithm for the characterization of multiple point inputs for linear fractional order systems. First, using polynomial modulating functions method and a suitable change of variables the problem of estimating the locations and the amplitudes of a multi-pointwise input is decoupled into two algebraic systems of equations. The first system is nonlinear and solves for the time locations iteratively, whereas the second system is linear and solves for the input’s amplitudes. Second, closed form formulas for both the time location and the amplitude are provided in the particular case of single point input. Finally, numerical examples are given to illustrate the performance of the proposed technique in both noise-free and noisy cases. The joint estimation of pointwise input and fractional differentiation orders is also presented. Furthermore, a discussion on the performance of the proposed algorithm is provided.

  18. Bayesian Estimation Of Shift Point In Poisson Model Under Asymmetric Loss Functions

    Directory of Open Access Journals (Sweden)

    uma srivastava

    2012-01-01

    Full Text Available The paper deals with estimating  shift point which occurs in any sequence of independent observations  of Poisson model in statistical process control. This shift point occurs in the sequence when  i.e. m  life data are observed. The Bayes estimator on shift point 'm' and before and after shift process means are derived for symmetric and asymmetric loss functions under informative and non informative priors. The sensitivity analysis of Bayes estimators are carried out by simulation and numerical comparisons with  R-programming. The results shows the effectiveness of shift in sequence of Poisson disribution .

  19. An improved adaptive weighting function method for State Estimation in Power Systems with VSC-MTDC

    Science.gov (United States)

    Zhao, Kun; Yang, Xiaonan; Lang, Yansheng; Song, Xuri; Wang, Minkun; Luo, Yadi; Wu, Lingyun; Liu, Peng

    2017-04-01

    This paper presents an effective approach for state estimation in power systems that include multi-terminal voltage source converter based high voltage direct current (VSC-MTDC), called improved adaptive weighting function method. The proposed approach is simplified in which the VSC-MTDC system is solved followed by the AC system. Because the new state estimation method only changes the weight and keeps the matrix dimension unchanged. Accurate and fast convergence of AC/DC system can be realized by adaptive weight function method. This method also provides the technical support for the simulation analysis and accurate regulation of AC/DC system. Both the oretical analysis and numerical tests verify practicability, validity and convergence of new method.

  20. An Energy-Based Limit State Function for Estimation of Structural Reliability in Shock Environments

    Directory of Open Access Journals (Sweden)

    Michael A. Guthrie

    2013-01-01

    Full Text Available limit state function is developed for the estimation of structural reliability in shock environments. This limit state function uses peak modal strain energies to characterize environmental severity and modal strain energies at failure to characterize the structural capacity. The Hasofer-Lind reliability index is briefly reviewed and its computation for the energy-based limit state function is discussed. Applications to two degree of freedom mass-spring systems and to a simple finite element model are considered. For these examples, computation of the reliability index requires little effort beyond a modal analysis, but still accounts for relevant uncertainties in both the structure and environment. For both examples, the reliability index is observed to agree well with the results of Monte Carlo analysis. In situations where fast, qualitative comparison of several candidate designs is required, the reliability index based on the proposed limit state function provides an attractive metric which can be used to compare and control reliability.

  1. Estimation Methods of the Point Spread Function Axial Position: A Comparative Computational Study

    Directory of Open Access Journals (Sweden)

    Javier Eduardo Diaz Zamboni

    2017-01-01

    Full Text Available The precise knowledge of the point spread function is central for any imaging system characterization. In fluorescence microscopy, point spread function (PSF determination has become a common and obligatory task for each new experimental device, mainly due to its strong dependence on acquisition conditions. During the last decade, algorithms have been developed for the precise calculation of the PSF, which fit model parameters that describe image formation on the microscope to experimental data. In order to contribute to this subject, a comparative study of three parameter estimation methods is reported, namely: I-divergence minimization (MIDIV, maximum likelihood (ML and non-linear least square (LSQR. They were applied to the estimation of the point source position on the optical axis, using a physical model. Methods’ performance was evaluated under different conditions and noise levels using synthetic images and considering success percentage, iteration number, computation time, accuracy and precision. The main results showed that the axial position estimation requires a high SNR to achieve an acceptable success level and higher still to be close to the estimation error lower bound. ML achieved a higher success percentage at lower SNR compared to MIDIV and LSQR with an intrinsic noise source. Only the ML and MIDIV methods achieved the error lower bound, but only with data belonging to the optical axis and high SNR. Extrinsic noise sources worsened the success percentage, but no difference was found between noise sources for the same method for all methods studied.

  2. Estimating age at a specified length from the von Bertalanffy growth function

    Science.gov (United States)

    Ogle, Derek H.; Isermann, Daniel A.

    2017-01-01

    Estimating the time required (i.e., age) for fish in a population to reach a specific length (e.g., legal harvest length) is useful for understanding population dynamics and simulating the potential effects of length-based harvest regulations. The age at which a population reaches a specific mean length is typically estimated by fitting a von Bertalanffy growth function to length-at-age data and then rearranging the best-fit equation to solve for age at the specified length. This process precludes the use of standard frequentist methods to compute confidence intervals and compare estimates of age at the specified length among populations. We provide a parameterization of the von Bertalanffy growth function that has age at a specified length as a parameter. With this parameterization, age at a specified length is directly estimated, and standard methods can be used to construct confidence intervals and make among-group comparisons for this parameter. We demonstrate use of the new parameterization with two data sets.

  3. Measurement of temporal regional cerebral perfusion with single-photon emission tomography predicts rate of decline in language function and survival in early Alzheimer`s disease

    Energy Technology Data Exchange (ETDEWEB)

    Claus, J.J.; Walstra, G.J.M.; Hijdra, A.; Gool, W.A. van [Department of Neurology, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Royen, E.A. van [Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam (Netherlands); Verbeeten, B. Jr. [Department of Radiology, Academic Medical Center, University of Amsterdam (Netherlands)

    1999-03-01

    We determined the relationship between regional cerebral blood flow (rCBF) measured with single-photon emission tomography (SPET) and decline in cognitive function and survival in Alzheimer`s disease. In a prospective follow-up study, 69 consecutively referred patients with early probable Alzheimer`s disease (NINCDS/ADRDA criteria) underwent SPET performed at the time of initial diagnosis using technetium-99m-labelled hexamethylpropylene amine oxime. Neuropsychological function was assessed at baseline and after 6 months and survival data were available on all patients, extending to 5.5 years of follow-up. Lower left temporal (P<0.01) and lower left parietal (P<0.01) rCBF were statistically significantly related to decline in language function after 6 months. The association between left temporal rCBF and survival was also statistically significant (P<0.05) using Cox proportional hazards regression analysis. Performing analysis with quartiles of the distribution, we found a threshold effect for low left temporal rCBF (rCBF<73.7%, P<0.01) and high risk of mortality. In this lowest quartile, median survival time was 2.7 years (follow-up to 5.2 years), compared with 4.4 years in the other quartiles (follow-up to 5.5 years). Kaplan-Meier survival curves showed statistically significant (P<0.05, log rank test) survival curves for the lowest versus other quartiles of left temporal rCBF. All results were unaffected by adjustment for age, sex, dementia severity, duration of symptoms, education and ratings of local cortical atrophy. We conclude that left temporal rCBF predicts decline in language function and survival in patients with early probable Alzheimer`s disease, with a threshold effect of low rCBF and high risk of mortality. (orig.) With 3 figs., 3 tabs., 44 refs.

  4. Estimating functional connectivity of wildlife habitat and its relevance to ecological risk assessment

    Science.gov (United States)

    Johnson, A.R.; Allen, C.R.; Simpson, K.A.N.

    2004-01-01

    Habitat fragmentation is a major threat to the viability of wildlife populations and the maintenance of biodiversity. Fragmentation relates to the sub-division of habitat intq disjunct patches. Usually coincident with fragmentation per se is loss of habitat, a reduction in the size of the remnant patches, and increasing distance between patches. Natural and anthropogenic processes leading to habitat fragmentation occur at many spatial scales, and their impacts on wildlife depend on the scales at which species interact with the landscape. The concept of functional connectivity captures this organism-based view of the relative ease of movement or degree of exchange between physically disjunct habitat patches. Functional connectivity of a given habitat arrangement for a given wildlife species depends on details of the organism's life history and behavioral ecology, but, for broad categories of species, quantities such as home range size and dispersal distance scale allometrically with body mass. These relationships can be incorporated into spatial analyses of functional connectivity, which can be quantified by indices or displayed graphically in maps. We review indices and GIS-based approaches to estimating functional connectivity, presenting examples from the literature and our own work on mammalian distributions. Such analyses can be readily incorporated within an ecological risk framework. Estimates of functional connectivity may be useful in a screening-level assessment of the impact of habitat fragmentation relative to other stressors, and may be crucial in detailed population modeling and viability analysis.

  5. On Estimation Of The Orientation Of Mobile Robots Using Turning Functions And SONAR Information

    Directory of Open Access Journals (Sweden)

    Dorel AIORDACHIOAIE

    2003-12-01

    Full Text Available SONAR systems are widely used by some artificial objects, e.g. robots, and by animals, e.g. bats, for navigation and pattern recognition. The objective of this paper is to present a solution on the estimation of the orientation in the environment of mobile robots, in the context of navigation, using the turning function approach. The results are shown to be accurate and can be used further in the design of navigation strategies of mobile robots.

  6. Scavenging superoxide selectively in mouse forebrain is associated with improved cardiac function and survival following myocardial infarction.

    Science.gov (United States)

    Lindley, Timothy E; Infanger, David W; Rishniw, Mark; Zhou, Yi; Doobay, Marc F; Sharma, Ram V; Davisson, Robin L

    2009-01-01

    Dysregulation in central nervous system (CNS) signaling that results in chronic sympathetic hyperactivity is now recognized to play a critical role in the pathogenesis of heart failure (HF) following myocardial infarction (MI). We recently demonstrated that adenovirus-mediated gene transfer of cytoplasmic superoxide dismutase (Ad-Cu/ZnSOD) to forebrain circumventricular organs, unique sensory structures that lack a blood-brain barrier and link peripheral blood-borne signals to central nervous system cardiovascular circuits, inhibits both the MI-induced activation of these central signaling pathways and the accompanying sympathoexcitation. Here, we tested the hypothesis that this forebrain-targeted reduction in oxidative stress translates into amelioration of the post-MI decline in myocardial function and increase in mortality. Adult C57BL/6 mice underwent left coronary artery ligation or sham surgery along with forebrain-targeted gene transfer of Ad-Cu/ZnSOD or a control vector. The results demonstrate marked MI-induced increases in superoxide radical formation in one of these forebrain regions, the subfornical organ (SFO). Ad-Cu/ZnSOD targeted to this region abolished the increased superoxide levels and led to significantly improved myocardial function compared with control vector-treated mice. This was accompanied by diminished levels of cardiomyocyte apoptosis in the Ad-Cu/ZnSOD but not the control vector-treated group. These effects of superoxide scavenging with Ad-Cu/ZnSOD in the forebrain paralleled increased post-MI survival rates compared with controls. This suggests that oxidative stress in the SFO plays a critical role in the deterioration of cardiac function following MI and underscores the promise of CNS-targeted antioxidant therapy for the treatment of MI-induced HF.

  7. Breeding goals for the Kenya dual purpose goat. II. Estimation of economic values for production and functional traits.

    Science.gov (United States)

    Bett, R C; Kosgey, I S; Bebe, B O; Kahi, A K

    2007-10-01

    Economic values for production traits (milk yield, MY, kg; 12-month sale weight, LW, kg; consumable meat percentage, CMP) and functional traits (doe live weight, DoWT, kg; number of kids weaned, NKW; kidding frequency, KF; kidding rate, KR, %; doe weaning rate, DoWR, %; doe survival rate, DoSR, %; post-weaning survival rate, PoSR, %; pre-weaning survival rate, PrSR, % and; residual feed intake of yearlings, RFIgamma, kg and does RFId, kg) were estimated for the Kenya Dual Purpose goat (KDPG) for systems under two bases of evaluation. The production systems included smallholder low-potential (SLP), smallholder medium-potential (SMP) and smallholder high-potential (SHP), while the bases of evaluation considered were fixed flock-size and fixed feed resource. Under both bases of evaluation, economic values were highest in SMP apart from the economic values for feed intake-related traits (RFIy and RFId). In SMP, the economic values under fixed flock-size scenario were KSh 71.61 (LW), 20.90 (MY), 45.20 (CMP), 13.68 (NKW), 3.61 (KF), 6.52 (KR), 12.39 (DoWR), 22.96 (DoSR), 22.87 (PoSR), 13.18 (PrSR), -2.76 (RFIy) and -3.00 (RFId). The corresponding economic values under fixed feed resources scenario were KSh 73.28, 29.39, 45.20, 16.91, 4.76, 9.45, 13.84, 25.67, 25.15, 16.19, -2.76 and -3.00. Generally in all production systems, economic values for most traits were higher under fixed feed resource than under fixed flock-size scenario. In all systems, the economic values for most of the traits were sensitive to changes in prices of feed, milk and meat. The positive economic values for most traits under fixed flock-size scenario and fixed feed resource indicates that a unit increase in genetic merit for the traits would have a positive effect on the profitability of the systems.

  8. Determination of Lateral Modulation Apodization Functions Using a Regularized, Weighted Least Squares Estimation

    Directory of Open Access Journals (Sweden)

    Chikayoshi Sumi

    2010-01-01

    Full Text Available Recently, work in this group has focused on the lateral cosine modulation method (LCM which can be used for next-generation ultrasound (US echo imaging and tissue displacement vector/strain tensor measurements (blood, soft tissues, etc.. For instance, in US echo imaging, a high lateral spatial resolution as well as a high axial spatial resolution can be obtained, and in tissue displacement vector measurements, accurate measurements of lateral tissue displacements as well as of axial tissue displacements can be realized. For an optimal determination of an apodization function for the LCM method, the regularized, weighted minimum-norm least squares (WMNLSs estimation method is presented in this study. For designed Gaussian-type point spread functions (PSFs with lateral modulation as an example, the regularized WMNLS estimation in simulations yields better approximations of the designed PSFs having wider lateral bandwidths than a Fraunhofer approximation and a singular-value decomposition (SVD. The usefulness of the regularized WMNLS estimation for the determination of apodization functions is demonstrated.

  9. Annual recapture and survival rates of two non-breeding adult populations of Roseate Terns Stema dougallii captured on the Great Barrier Reef, Australia, and estimates of their population sizes

    Science.gov (United States)

    O'Neill, P.; Minton, C.D.T.; Nisbet, I.C.T.; Hines, J.E.

    2008-01-01

    Capture-recapture data from two disparate breeding populations of Roseate Terns (Sterna dougallii) captured together as non-breeding individuals from 2002 to 2007 in the southern Great Barrier Reef. Australia were analyzed for both survival rate and recapture rate. The average annual survival rate for the birds from the Asian population (S. d. bangsi) (0.901) is higher than that of the other population of unknown breeding origin (0.819). There was large variability in survival in both populations among years, but the average survival rate of 0.85 is similar to estimates for the same species in North America. The Cormack-Jolly-Seber models used in program MARK to estimate survival rates also produced estimated of recapture probabilities and population sizes. These estimates of population size were 29,000 for S. D. bangsi and 8,300 for the study area and much larger than the documented numbers in the likely breeding areas, suggesting that many breeding sites are currently unknown.

  10. Joint entropy for space and spatial frequency domains estimated from psychometric functions of achromatic discrimination.

    Science.gov (United States)

    Silveira, Vladímir de Aquino; Souza, Givago da Silva; Gomes, Bruno Duarte; Rodrigues, Anderson Raiol; Silveira, Luiz Carlos de Lima

    2014-01-01

    We used psychometric functions to estimate the joint entropy for space discrimination and spatial frequency discrimination. Space discrimination was taken as discrimination of spatial extent. Seven subjects were tested. Gábor functions comprising unidimensionalsinusoidal gratings (0.4, 2, and 10 cpd) and bidimensionalGaussian envelopes (1°) were used as reference stimuli. The experiment comprised the comparison between reference and test stimulithat differed in grating's spatial frequency or envelope's standard deviation. We tested 21 different envelope's standard deviations around the reference standard deviation to study spatial extent discrimination and 19 different grating's spatial frequencies around the reference spatial frequency to study spatial frequency discrimination. Two series of psychometric functions were obtained for 2%, 5%, 10%, and 100% stimulus contrast. The psychometric function data points for spatial extent discrimination or spatial frequency discrimination were fitted with Gaussian functions using the least square method, and the spatial extent and spatial frequency entropies were estimated from the standard deviation of these Gaussian functions. Then, joint entropy was obtained by multiplying the square root of space extent entropy times the spatial frequency entropy. We compared our results to the theoretical minimum for unidimensional Gábor functions, 1/4π or 0.0796. At low and intermediate spatial frequencies and high contrasts, joint entropy reached levels below the theoretical minimum, suggesting non-linear interactions between two or more visual mechanisms. We concluded that non-linear interactions of visual pathways, such as the M and P pathways, could explain joint entropy values below the theoretical minimum at low and intermediate spatial frequencies and high contrasts. These non-linear interactions might be at work at intermediate and high contrasts at all spatial frequencies once there was a substantial decrease in joint

  11. Induced Neural Stem Cells Achieve Long-Term Survival and Functional Integration in the Adult Mouse Brain

    Directory of Open Access Journals (Sweden)

    Kathrin Hemmer

    2014-09-01

    Full Text Available Differentiated cells can be converted directly into multipotent neural stem cells (i.e., induced neural stem cells [iNSCs]. iNSCs offer an attractive alternative to induced pluripotent stem cell (iPSC technology with regard to regenerative therapies. Here, we show an in vivo long-term analysis of transplanted iNSCs in the adult mouse brain. iNSCs showed sound in vivo long-term survival rates without graft overgrowths. The cells displayed a neural multilineage potential with a clear bias toward astrocytes and a permanent downregulation of progenitor and cell-cycle markers, indicating that iNSCs are not predisposed to tumor formation. Furthermore, the formation of synaptic connections as well as neuronal and glial electrophysiological properties demonstrated that differentiated iNSCs migrated, functionally integrated, and interacted with the existing neuronal circuitry. We conclude that iNSC long-term transplantation is a safe procedure; moreover, it might represent an interesting tool for future personalized regenerative applications.

  12. Blockade of cannabinoid CB1 receptors improves renal function, metabolic profile, and increased survival of obese Zucker rats.

    Science.gov (United States)

    Janiak, P; Poirier, B; Bidouard, J-P; Cadrouvele, C; Pierre, F; Gouraud, L; Barbosa, I; Dedio, J; Maffrand, J-P; Le Fur, G; O'Connor, S; Herbert, J-M

    2007-12-01

    Obesity is a major risk factor in the development of chronic renal failure. Rimonabant, a cannabinoid CB1 receptor antagonist, improves body weight and metabolic disorders; however, its effect on mortality and chronic renal failure associated with obesity is unknown. Obese Zucker rats received either rimonabant or vehicle for 12 months and were compared to a pair-fed but untreated group of obese rats. Mortality in the obese rats was significantly reduced by rimonabant along with a sustained decrease in body weight, transient reduction in food intake, and an increase in plasma adiponectin. This was associated with significant reduction in plasma total cholesterol, low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio, triglycerides, glucose, norepinephrine, plasminogen activator inhibitor 1, and preservation of pancreatic weight and beta-cell mass index. The cannabinoid antagonist attenuated the increase in proteinuria, urinary N-acetylglucosaminidase excretion, plasma creatinine, and urea nitrogen levels while improving creatinine clearance. Renal hypertrophy along with glomerular and tubulointerstitial lesions were reduced by rimonabant. Although the drug did not modify hemodynamics, it normalized the pressor response to angiotensin II. Our study suggests that in a rat model of chronic renal failure due to obesity, rimonabant preserves renal function and increases survival.

  13. QMEANclust: estimation of protein model quality by combining a composite scoring function with structural density information

    Directory of Open Access Journals (Sweden)

    Schwede Torsten

    2009-05-01

    Full Text Available Abstract Background The selection of the most accurate protein model from a set of alternatives is a crucial step in protein structure prediction both in template-based and ab initio approaches. Scoring functions have been developed which can either return a quality estimate for a single model or derive a score from the information contained in the ensemble of models for a given sequence. Local structural features occurring more frequently in the ensemble have a greater probability of being correct. Within the context of the CASP experiment, these so called consensus methods have been shown to perform considerably better in selecting good candidate models, but tend to fail if the best models are far from the dominant structural cluster. In this paper we show that model selection can be improved if both approaches are combined by pre-filtering the models used during the calculation of the structural consensus. Results Our recently published QMEAN composite scoring function has been improved by including an all-atom interaction potential term. The preliminary model ranking based on the new QMEAN score is used to select a subset of reliable models against which the structural consensus score is calculated. This scoring function called QMEANclust achieves a correlation coefficient of predicted quality score and GDT_TS of 0.9 averaged over the 98 CASP7 targets and perform significantly better in selecting good models from the ensemble of server models than any other groups participating in the quality estimation category of CASP7. Both scoring functions are also benchmarked on the MOULDER test set consisting of 20 target proteins each with 300 alternatives models generated by MODELLER. QMEAN outperforms all other tested scoring functions operating on individual models, while the consensus method QMEANclust only works properly on decoy sets containing a certain fraction of near-native conformations. We also present a local version of QMEAN for the per

  14. Functional soil microbial diversity across Europe estimated by EEA, MicroResp and BIOLOG

    DEFF Research Database (Denmark)

    Winding, Anne; Rutgers, Michiel; Creamer, Rachel

    Soil microorganisms are abundant and essential for the bio-geochemical processes of soil, soil quality and soil ecosystem services. All this is dependent on the actual functions the microbial communities are performing in the soil. Measuring soil respiration has for many years been the basis...... of estimating soil microbial activity. However, today several techniques are in use for determining microbial functional diversity and assessing soil biodiversity: Methods based on CO2 development by the microbes such as substrate induced respiration (SIR) on specific substrates have lead to the development...... of MicroResp and Community Level Physiological Profile (CLPP), while soil enzymatic activity are being assayed by Extracellular Enzyme Activity (EEA) based on MUF-substrates. Here we compared and contrasted the three techniques of assessing soil microbial functional diversity in a European transect...

  15. Estimation of Time-Varying Coherence and Its Application in Understanding Brain Functional Connectivity

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    Cheng Liu

    2010-01-01

    Full Text Available Time-varying coherence is a powerful tool for revealing functional dynamics between different regions in the brain. In this paper, we address ways of estimating evolutionary spectrum and coherence using the general Cohen's class distributions. We show that the intimate connection between the Cohen's class-based spectra and the evolutionary spectra defined on the locally stationary time series can be linked by the kernel functions of the Cohen's class distributions. The time-varying spectra and coherence are further generalized with the Stockwell transform, a multiscale time-frequency representation. The Stockwell measures can be studied in the framework of the Cohen's class distributions with a generalized frequency-dependent kernel function. A magnetoencephalography study using the Stockwell coherence reveals an interesting temporal interaction between contralateral and ipsilateral motor cortices under the multisource interference task.

  16. Estimates on potential functions and boundary behavior of positive solutions for sublinear Dirichlet problems

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    Ramzi Alsaedi

    2014-01-01

    Full Text Available We give global estimates on some potential of functions in a bounded domain of the Euclidean space ${\\mathbb{R}}^n\\; (n\\geq 2$. These functions may be singular near the boundary and are globally comparable to a product of a power of the distance to the boundary by some particularly well behaved slowly varying function near zero. Next, we prove the existence and uniqueness of a positive solution for the integral equation $u=V(a u^{\\sigma}$ with $0\\leq \\sigma <1$, where V belongs to a class of kernels that contains in particular the potential kernel of the classical Laplacian $V=(-\\Delta^{-1}$ or the fractional laplacian $V=(-\\Delta^{\\alpha/2}$, $0<\\alpha<2$.

  17. Bayesian Estimation of Inequality and Poverty Indices in Case of Pareto Distribution Using Different Priors under LINEX Loss Function

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    Kamaljit Kaur

    2015-01-01

    Full Text Available Bayesian estimators of Gini index and a Poverty measure are obtained in case of Pareto distribution under censored and complete setup. The said estimators are obtained using two noninformative priors, namely, uniform prior and Jeffreys’ prior, and one conjugate prior under the assumption of Linear Exponential (LINEX loss function. Using simulation techniques, the relative efficiency of proposed estimators using different priors and loss functions is obtained. The performances of the proposed estimators have been compared on the basis of their simulated risks obtained under LINEX loss function.

  18. Bayesian switching factor analysis for estimating time-varying functional connectivity in fMRI.

    Science.gov (United States)

    Taghia, Jalil; Ryali, Srikanth; Chen, Tianwen; Supekar, Kaustubh; Cai, Weidong; Menon, Vinod

    2017-07-15

    There is growing interest in understanding the dynamical properties of functional interactions between distributed brain regions. However, robust estimation of temporal dynamics from functional magnetic resonance imaging (fMRI) data remains challenging due to limitations in extant multivariate methods for modeling time-varying functional interactions between multiple brain areas. Here, we develop a Bayesian generative model for fMRI time-series within the framework of hidden Markov models (HMMs). The model is a dynamic variant of the static factor analysis model (Ghahramani and Beal, 2000). We refer to this model as Bayesian switching factor analysis (BSFA) as it integrates factor analysis into a generative HMM in a unified Bayesian framework. In BSFA, brain dynamic functional networks are represented by latent states which are learnt from the data. Crucially, BSFA is a generative model which estimates the temporal evolution of brain states and transition probabilities between states as a function of time. An attractive feature of BSFA is the automatic determination of the number of latent states via Bayesian model selection arising from penalization of excessively complex models. Key features of BSFA are validated using extensive simulations on carefully designed synthetic data. We further validate BSFA using fingerprint analysis of multisession resting-state fMRI data from the Human Connectome Project (HCP). Our results show that modeling temporal dependencies in the generative model of BSFA results in improved fingerprinting of individual participants. Finally, we apply BSFA to elucidate the dynamic functional organization of the salience, central-executive, and default mode networks-three core neurocognitive systems with central role in cognitive and affective information processing (Menon, 2011). Across two HCP sessions, we demonstrate a high level of dynamic interactions between these networks and determine that the salience network has the highest temporal

  19. Assessing a learning process with functional ANOVA estimators of EEG power spectral densities.

    Science.gov (United States)

    Gutiérrez, David; Ramírez-Moreno, Mauricio A

    2016-04-01

    We propose to assess the process of learning a task using electroencephalographic (EEG) measurements. In particular, we quantify changes in brain activity associated to the progression of the learning experience through the functional analysis-of-variances (FANOVA) estimators of the EEG power spectral density (PSD). Such functional estimators provide a sense of the effect of training in the EEG dynamics. For that purpose, we implemented an experiment to monitor the process of learning to type using the Colemak keyboard layout during a twelve-lessons training. Hence, our aim is to identify statistically significant changes in PSD of various EEG rhythms at different stages and difficulty levels of the learning process. Those changes are taken into account only when a probabilistic measure of the cognitive state ensures the high engagement of the volunteer to the training. Based on this, a series of statistical tests are performed in order to determine the personalized frequencies and sensors at which changes in PSD occur, then the FANOVA estimates are computed and analyzed. Our experimental results showed a significant decrease in the power of [Formula: see text] and [Formula: see text] rhythms for ten volunteers during the learning process, and such decrease happens regardless of the difficulty of the lesson. These results are in agreement with previous reports of changes in PSD being associated to feature binding and memory encoding.

  20. Estimation of non-linear growth models by linearization: a simulation study using a Gompertz function

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    Mäntysaari Esa A

    2006-06-01

    Full Text Available Abstract A method based on Taylor series expansion for estimation of location parameters and variance components of non-linear mixed effects models was considered. An attractive property of the method is the opportunity for an easily implemented algorithm. Estimation of non-linear mixed effects models can be done by common methods for linear mixed effects models, and thus existing programs can be used after small modifications. The applicability of this algorithm in animal breeding was studied with simulation using a Gompertz function growth model in pigs. Two growth data sets were analyzed: a full set containing observations from the entire growing period, and a truncated time trajectory set containing animals slaughtered prematurely, which is common in pig breeding. The results from the 50 simulation replicates with full data set indicate that the linearization approach was capable of estimating the original parameters satisfactorily. However, estimation of the parameters related to adult weight becomes unstable in the case of a truncated data set.

  1. A Bayesian hierarchical mixture model for platelet derived growth factor receptor phosphorylation to improve estimation of progression-free survival in prostate cancer

    Science.gov (United States)

    Morita, Satoshi; Thall, Peter F.; Bekele, B. Nebiyou; Mathew, Paul

    2010-01-01

    SUMMARY Advances in understanding the biological underpinnings of many cancers have led increasingly to the use of molecularly targeted anti-cancer therapies. Because the platelet-derived growth factor receptor (PDGFR) has been implicated in the progression of prostate cancer bone metastases, it is of great interest to examine possible relationships between PDGFR inhibition and therapeutic outcomes. Here, we analyze the association between change in activated PDGFR (p-PDGFR) and progression free survival (PFS) time based on large within-patient samples of cell-specific p-PDGFR values taken before and after treatment from each of 88 prostate cancer patients. To utilize these paired samples as covariate data in a regression model for PFS time, and because the p-PDGFR distributions are bimodal, we first employ a Bayesian hierarchical mixture model to obtain a deconvolution of the pre-treatment and post-treatment within-patient p-PDGFR distributions. We evaluate fits of the mixture model and a non-mixture model that ignores the bimodality by using a supnorm metric to compare the empirical distribution of each p-PDGFR data set with the corresponding fitted distribution under each model. Our results show that first using the mixture model to account for the bimodality of the within-patient p-PDGFR distributions, and then using the posterior within-patient component mean changes in p-PDGFR so obtained as covariates in the regression model for PFS time provides an improved estimation. PMID:20390057

  2. Histopathological analysis of pre-implantation donor kidney biopsies: association with graft survival and function in one year post-transplantation

    Directory of Open Access Journals (Sweden)

    Karla Lais Pêgas

    2014-04-01

    Full Text Available Introduction: Pre-implantation kidney biopsy is a decision-making tool when considering the use of grafts from deceased donors with expanded criteria, implanting one or two kidneys and comparing this to post-transplantation biopsies. The role of histopathological alterations in kidney compartments as a prognostic factor in graft survival and function has had conflicting results. Objective: This study evaluated the prevalence of chronic alterations in pre-implant biopsies of kidney grafts and the association of findings with graft function and survival in one year post-transplant. Methods: 110 biopsies were analyzed between 2006 and 2009 at Santa Casa de Porto Alegre, including live donors, ideal deceased donors and those with expanded criteria. The score was computed according to criteria suggested by Remuzzi. The glomerular filtration rate (GFR was calculated using the abbreviated MDRD formula. Results: No statistical difference was found in the survival of donors stratified according to Remuzzi criteria. The GFR was significantly associated with the total scores in the groups with mild and moderate alterations, and in the kidney compartments alone, by univariate analysis. The multivariate model found an association with the presence of arteriosclerosis, glomerulosclerosis, acute rejection and delayed graft function. Conclusion: Pre-transplant chronic kidney alterations did not influence the post-transplantation one-year graft survival, but arteriosclerosis and glomerulosclerosis is predictive of a worse GFR. Delayed graft function and acute rejection are independent prognostic factors.

  3. Admissible and Minimax Estimators of a Lower Bounded Scale Parameter of a Gamma Distribution under the Entropy Loss Function

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    M. Nasr Esfahani

    2009-03-01

    Full Text Available This paper is concerned with admissible and minimax estimation of scale parameter θ of a gamma distribution under the entropy loss function, when it is known that θ > a for some known a > 0. An admissible minimax estimator of θ, which is the pointwise limit of a sequence of Bayes estimators, is derived. Also, the admissible estimators and the only minimax estimator of θ in the class of truncated linear estimators are obtained. Finally, the results are extended to a subclass of scale parameter exponential family and the family of transformed chi-square distributions

  4. Optimal replacement time estimation for machines and equipment based on cost function

    Directory of Open Access Journals (Sweden)

    J. Šebo

    2013-01-01

    Full Text Available The article deals with a multidisciplinary issue of estimating the optimal replacement time for the machines. Considered categories of machines, for which the optimization method is usable, are of the metallurgical and engineering production. Different models of cost function are considered (both with one and two variables. Parameters of the models were calculated through the least squares method. Models testing show that all are good enough, so for estimation of optimal replacement time is sufficient to use simpler models. In addition to the testing of models we developed the method (tested on selected simple model which enable us in actual real time (with limited data set to indicate the optimal replacement time. The indicated time moment is close enough to the optimal replacement time t*.

  5. Estimating the Persistence and the Autocorrelation Function of a Time Series that is Measured with Error

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    2014-01-01

    An economic time series can often be viewed as a noisy proxy for an underlying economic variable. Measurement errors will influence the dynamic properties of the observed process and may conceal the persistence of the underlying time series. In this paper we develop instrumental variable (IV......) methods for extracting information about the latent process. Our framework can be used to estimate the autocorrelation function of the latent volatility process and a key persistence parameter. Our analysis is motivated by the recent literature on realized volatility measures that are imperfect estimates...... of actual volatility. In an empirical analysis using realized measures for the Dow Jones industrial average stocks, we find the underlying volatility to be near unit root in all cases. Although standard unit root tests are asymptotically justified, we find them to be misleading in our application despite...

  6. Estimating the Persistence and the Autocorrelation Function of a Time Series that is Measured with Error

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    An economic time series can often be viewed as a noisy proxy for an underlying economic variable. Measurement errors will influence the dynamic properties of the observed process and may conceal the persistence of the underlying time series. In this paper we develop instrumental variable (IV......) methods for extracting information about the latent process. Our framework can be used to estimate the autocorrelation function of the latent volatility process and a key persistence parameter. Our analysis is motivated by the recent literature on realized (volatility) measures, such as the realized...... variance, that are imperfect estimates of actual volatility. In an empirical analysis using realized measures for the DJIA stocks we find the underlying volatility to be near unit root in all cases. Although standard unit root tests are asymptotically justified, we find them to be misleading in our...

  7. Estimation of the POD function and the LOD of a qualitative microbiological measurement method.

    Science.gov (United States)

    Wilrich, Cordula; Wilrich, Peter-Theodor

    2009-01-01

    Qualitative microbiological measurement methods in which the measurement results are either 0 (microorganism not detected) or 1 (microorganism detected) are discussed. The performance of such a measurement method is described by its probability of detection as a function of the contamination (CFU/g or CFU/mL) of the test material, or by the LOD(p), i.e., the contamination that is detected (measurement result 1) with a specified probability p. A complementary log-log model was used to statistically estimate these performance characteristics. An intralaboratory experiment for the detection of Listeria monocytogenes in various food matrixes illustrates the method. The estimate of LOD50% is compared with the Spearman-Kaerber method.

  8. Lithium-ion battery state of function estimation based on fuzzy logic algorithm with associated variables

    Science.gov (United States)

    Gan, L.; Yang, F.; Shi, Y. F.; He, H. L.

    2017-11-01

    Many occasions related to batteries demand to know how much continuous and instantaneous power can batteries provide such as the rapidly developing electric vehicles. As the large-scale applications of lithium-ion batteries, lithium-ion batteries are used to be our research object. Many experiments are designed to get the lithium-ion battery parameters to ensure the relevance and reliability of the estimation. To evaluate the continuous and instantaneous load capability of a battery called state-of-function (SOF), this paper proposes a fuzzy logic algorithm based on battery state-of-charge(SOC), state-of-health(SOH) and C-rate parameters. Simulation and experimental results indicate that the proposed approach is suitable for battery SOF estimation.

  9. Cancer Cell-derived Exosomes Induce Mitogen-activated Protein Kinase-dependent Monocyte Survival by Transport of Functional Receptor Tyrosine Kinases*

    Science.gov (United States)

    Song, Xiao; Ding, Yanping; Liu, Gang; Yang, Xiao; Zhao, Ruifang; Zhang, Yinlong; Zhao, Xiao; Anderson, Gregory J.; Nie, Guangjun

    2016-01-01

    Tumor-associated macrophages (TAM) play pivotal roles in cancer initiation and progression. Monocytes, the precursors of TAMs, normally undergo spontaneous apoptosis within 2 days, but can subsist in the inflammatory tumor microenvironment for continuous survival and generation of sufficient TAMs. The mechanisms underlying tumor-driving monocyte survival remain obscure. Here we report that cancer cell-derived exosomes were crucial mediators for monocyte survival in the inflammatory niche. Analysis of the survival-promoting molecules in monocytes revealed that cancer cell-derived exosomes activated Ras and extracellular signal-regulated kinases in the mitogen-activated protein kinase (MAPK) pathway, resulting in the prevention of caspase cleavage. Phosphorylated receptor tyrosine kinases (RTKs), such as phosphorylated epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER-2), were abundantly expressed in cancer cell-derived exosomes. Knock-out of EGFR or/and HER-2, or alternatively, inhibitors against their phosphorylation significantly disturbed the exosome-mediated activation of the MAPK pathway, inhibition of caspase cleavage, and increase in survival rate in monocytes. Moreover, the deprived survival-stimulating activity of exosomes due to null expression of EGFR and HER-2 could be restored by activation of another RTK, insulin receptor. Overall, our study uncovered a mechanism of tumor-associated monocyte survival and demonstrated that cancer cell-derived exosomes can stimulate the MAPK pathway in monocytes through transport of functional RTKs, leading to inactivation of apoptosis-related caspases. This work provides insights into the long sought question on monocyte survival prior to formation of plentiful TAMs in the tumor microenvironment. PMID:26895960

  10. Implanted spike wave electric stimulation promotes survival of the bone marrow mesenchymal stem cells and functional recovery in the spinal cord injured rats.

    Science.gov (United States)

    Wu, Wenliang; Zhao, Hua; Xie, Bin; Liu, Haichun; Chen, Yunzhen; Jiao, Guangjun; Wang, Hongliang

    2011-03-10

    Transplantation of bone marrow-derived mesenchymal stromal cells (BMSCs) into the injured spinal cord may provide therapeutic benefit, but its application is limited by their poor survival and low differentiation rate into neurons. Electrical stimulation (ES) has been reported to promote survival and differentiation of the BMSCs. Therefore we investigated whether implanted spike wave ES could improve survival of BMSCs after transplantation and result in functional improvement in animals with spinal cord injury. Our results showed that the number and ratio of survived BMSCs near the lesion site were significantly increased in the BMSCs+ES-treated group as compared to BMSCs transplantation or ES treatment alone group. Furthermore, results from BBB scales, SSEP and DTI demonstrated a significant improved functional recovery in the BMSCs+ES group. This indicated that implanted spike wave ES could promote the bioactivity of BMSCs and their survival. This represents a new therapeutic potential of the combination of BMSCs transplantation with implanted spike wave ES to treat spinal cord injury. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  11. ESTIMATING THE PRODUCTION FUNCTION IN THE CASE OF ROMANIA METODOLOGY AND RESULTS

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    Simuț Ramona Marinela

    2015-07-01

    Full Text Available The problem of economic growth is a headline concern among economists, mathematicians and politicians. This is because of the major impact of economic growth on the entire population of a country, which has made achieving or maintaining a sustained growth rate the major objective of macroeconomic policy of any country. Thus, in order to identify present sources of economic growth for Romania in our study we used the Cobb-Douglas type production function. The basic variables of this model are represented by work factors, capital stock and the part of economic growth determined by the technical progress, the Solow residue or total productivity of production factors. To estimate this production function in the case of Romania, we used the quarter statistical data from the period between 2000 – first quarter and 2014 – fourth quarter; the source of the data was Eurostat. The Cobb-Douglas production function with the variables work and capital is valid in Romania’s case because it has the parameters of the exogenous variables significantly different from zero. This model became valid after we eliminated the autocorrelation of errors. Removing the autocorrelation of errors does not alter the structure of the production function. The adjusted R2 determination coefficient, as well as the α and β coefficients have values close to those from the first estimated equation. The regression of the GDP is characterized by marginal decreasing efficiency of the capital stock (α > 1 and decreasing efficiency of work (β < 1. In our case the sum of the α and β coefficients is below 1 (it is 0.75 as well as in the case of the second model (0.89, which corresponds to the decreasing efficiency of the production function. Concerning the working population of Romania, it registered a growing trend, starting with 2000 until 2005, a period that coincided with a sustained economic growth.

  12. ESTIMATING THE COBB DOUGLAS PRODUCTION FUNCTION INCLUDING THE EXPORT AND OPENNESS IN THE CASE OF ROMANIA

    Directory of Open Access Journals (Sweden)

    Simuț Ramona Marinela

    2015-07-01

    Full Text Available Economic convergence theories are closely related to economic growth theories. The first to study the economic growth phenomenon were the classics A. Smith, D. Ricardo, Th. Malthus, whose models of so-called classic models, do not take into account the contribution of technical progress in increasing production per capita. In order to analyze the convergence process, as a result of economic growth, a series of studies have been created to check the convergent or divergent nature of economies. Thus, in order to identify present sources of economic growth for Romania in our study we have used the Cobb-Douglas type production function. The variables that are the base of this model are represented by work factors and capital stock, to which we have added two explicative variables of economic growth: export and the openness degree of the economy. The two economic growth variables have been included in the model due to their favorable influence on the Solow residue. To estimate this production function, quarterly statistical data from the period between 2000 – first quarter and 2014 – fourth quarter have been used; the source of the data was Eurostat. As to what the first estimated model is concerned, the Cobb-Douglas production function including the export variable are both valid in Romania’s case, this have the parameters of the exogenous variables significantly different from zero, while the second estimated model, which contains the openness variable, is not valid. Its independent variable coefficient is not significantly different from zero, at the level of the entire population. This shows us that the inclusion of the degree of openness of the economy variable in the model affects the significance degree of the model and in order to validate it, the variable must be eliminated. Therefore, we can state that in Romania an increase of the openness degree of the economy due to capital imports would not generate an improvement in what type of

  13. Hypothermic machine perfusion reduces delayed graft function and improves one-year graft survival of kidneys from expanded criteria donors: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Baoping Jiao

    Full Text Available BACKGROUND: Expanded criteria donors (ECDs are currently accepted as potential sources to increase the donor pool and to provide more chances of kidney transplantation for elderly recipients who would not survive long waiting periods. Hypothermic machine perfusion (HMP is designed to mitigate the deleterious effects of simple cold storage (CS on the quality of preserved organs, particularly when the donor is in a marginal status. METHODS: We compared the transplant outcomes in patients receiving ECD kidneys with either HMP or CS graft preservation. Articles from the MEDLINE, EMBASE and Cochrane Library databases were searched and all studies reporting outcomes from HMP versus CS methods of kidney preservation were included in this meta-analysis. The parameters analyzed included the incidence of delayed graft function (DGF, primary non-function (PNF and one-year graft and patient survival. RESULTS: A total of seven studies qualified for the review, involving 2374 and 8716 kidney grafts with HMP or CS preservation respectively, all from ECD donors. The incidence of delayed graft function (DGF was significantly reduced with an odd ratio(OR of 0.59 (95% CI 0.54-0.66, P<0.001 and one-year graft survival was significantly improved with an OR of 1.12 (95% CI 1.03-1.21, P = 0.005 in HMP preservation compared to CS. However, there was no difference in the incidence of PNF (OR 0.54, 95% CI 0.21-1.40, P = 0.20, and one-year patient survival (OR 0.98, 95% CI 0.94-1.02, P = 0.36 between HMP and CS preservation. CONCLUSIONS: HMP was associated with a reduced incidence of DGF and an with increased one-year graft survival, but it was not associated with the incidence of PNF and one-year patient survival.

  14. Characterization of functional, safety, and gut survival related characteristics of Lactobacillus strains isolated from farmhouse goat's milk cheeses.

    Science.gov (United States)

    Lavilla-Lerma, L; Pérez-Pulido, R; Martínez-Bueno, M; Maqueda, M; Valdivia, E

    2013-05-15

    A set of 80 Lactobacillus strains (36 Lactobacillus plantarum and 44 Lactobacillus paracasei) isolated from Spanish farmhouse cheeses have been studied as to their functional and safety properties and their survival under gut-related conditions. None of these 80 Lactobacillus strains were able to hydrolyse starch. A high percentage of L. plantarum and L. paracasei strains were, however, capable of hydrolysing casein (86.1% and 68.2% respectively). For the other characteristics investigated, L. plantarum strains generally had more positive responses than L. paracasei. The latter strains tested negative for most of these characteristics, with the exception of stachyose hydrolysis, which was positive in six strains of L. paracasei. A high percentage (91.7%) of L. plantarum produced haemo-dependent catalase. Phytase was present in 10 L. plantarum and in 2 L. paracasei. Most L. plantarum (83.3%) but no L. paracasei hydrolysed bile salts. All strains were completely resistant to a challenge of pH3, but many showed a loss of viability after a subsequent exposure to 0.3% oxgall; in fact, only one L. paracasei strain and 33 L. plantarum strains (91.67%) were tolerant to both stresses. L. plantarum Mb25 and L. plantarum Mb26 were the most adherent to Caco-2 cells (adherence percentages of 36 and 7% respectively). These two strains were also the most adherent to HeLa 229 cells, with 19.3 and 16.0% adhesion respectively. The Mb26 strain inhibited the adhesion of Listeria monocytogenes to Caco-2 cells when added simultaneously to Listeria and also when added 1h before the pathogen (21.0% and 51.6% adhesion inhibition, respectively). Production of H2O2 was detected in 38.9% of L. plantarum strains and in 9.1% of L. paracasei. Twelve L. plantarum and eight L. paracasei strains produced bacteriocin-like inhibitors. PCR amplifications of several plantaricin genes suggest that all the bacteriocinogenic strains may produce plantaricin E/F and some may also manufacture the plantaricin

  15. Estimation of resting state effective connectivity in epilepsy using direct-directed transfer function.

    Science.gov (United States)

    Maharathi, Biswajit; Loeb, Jeffrey A; Patton, James

    2016-08-01

    There has been an increasing demand among neuroscientists to understand the complex network of functionally connected neural assemblies in the human brain. For this purpose, computational EEG research is widely used by researchers due to its remarkable advantage in providing high temporal resolution, and ease of analysis across different frequency bands. Here we analyzed Electrocorticographic (ECoG) signals of electrodes placed on frontal-parietal neocortex brain region of 8 pediatric epileptic patients. In order to evaluate the directed causal relationship among different brain regions, we employed a Granger causality based multivariate connectivity estimator named direct Directed Transfer Function (dDTF) to identify signal propagations among the selected set of electrode in the frequency range 1-50Hz. A consistent network pattern emerged that was unique to each patient. The fidelity of such dDTF-derived connectivity patterns can support a clearer understanding of effective connectivity in epileptic networks.

  16. ON THE ESTIMATION OF THE SUPPLY FUNCTION OF THE HUNGARIAN PORK MARKET

    Directory of Open Access Journals (Sweden)

    Levente Nyárs

    2006-07-01

    Full Text Available An uncertain situation can be observed in the Hungarian pork market in the last four years. The main reasons for that are the increasing quantities of pork import, the decrease of pig meat consumption, and the decreasing competitiveness of the Hungarian farms. Instead of well-defi ned control of the market ad hoc measurements have been taking place. The farmers found themselves in an uncertain position and they were unable to make appropriate decisions. The market price changed signifi cantly several times within this period making the mathematical analysis of the supply function possible. In this paper the pork supply is estimated under various scenarios. The supply function is approximated by several regression equations. All of these give the same result in extreme market situations.

  17. Gastrointestinal Functionality of Aquatic Animal (Oreochromis niloticus) Carcass in Water Allows Estimating Time of Death.

    Science.gov (United States)

    Hahor, Waraporn; Thongprajukaew, Karun; Yoonram, Krueawan; Rodjaroen, Somrak

    2016-11-01

    Postmortem changes have been previously studied in some terrestrial animal models, but no prior information is available on aquatic species. Gastrointestinal functionality was investigated in terms of indices, protein concentration, digestive enzyme activity, and scavenging activity, in an aquatic animal model, Nile tilapia, to assess the postmortem changes. Dead fish were floated indoors, and samples were collected within 48 h after death. Stomasomatic index decreased with postmortem time and correlated positively with protein, pepsin-specific activity, and stomach scavenging activity. Also intestosomatic index decreased significantly and correlated positively with protein, specific activity of trypsin, chymotrypsin, amylase, lipase, and intestinal scavenging activity. In their postmortem changes, the digestive enzymes exhibited earlier lipid degradation than carbohydrate or protein. The intestine changed more rapidly than the stomach. The findings suggest that the postmortem changes of gastrointestinal functionality can serve as primary data for the estimation of time of death of an aquatic animal. © 2016 American Academy of Forensic Sciences.

  18. Rapid Change in Residual Renal Function Decline Is Associated with Lower Survival and Worse Residual Renal Function Preservation in Peritoneal Dialysis Patients.

    Science.gov (United States)

    Hu, Susie L; Joshi, Priyanka; Kaplan, Mark; Lefkovitz, Judy; Poenariu, Andreea; Dworkin, Lance D; Michaud, Dominique S

    2017-01-01

    The survival advantage observed among peritoneal dialysis patients early on after dialysis initiation has been largely attributed to residual renal function (RRF) preservation due to higher baseline residual function and fewer comorbidities. We hypothesize that a rapid decline in RRF is associated with higher risk of anuria and mortality. In a retrospective cohort study of 581 subjects on peritoneal dialysis with longitudinal prevalent data, we assessed whether RRF change over time, in addition to baseline RRF, increased risk of mortality and anuria using Kaplan-Meier analysis and Cox proportional hazard analysis to control for known risk factors. Rapid RRF decline (≥ 0.09 decline) over a 12-month period was associated with a 2.6-fold increase in the risk of death (hazard ratio [HR] 2.60, 95% confidence interval [CI] 1.66 - 4.07, compared with anuria (HR 2.06, 95% CI 1.24 - 3.42). Each quartile of increasing severity of RRF decline over a 12-month period increased risk incrementally for death (2 nd quartile: HR 3.04, CI 1.26 - 7.34; 3 rd quartile: HR 4.01, CI 1.71 - 9.83; 4 th quartile HR 5.78, CI 2.10 - 15.9) and generally for anuria (quartiles with HR 5.72 - 7.21). The escalating risk of mortality and anuria was greater for those with diabetes mellitus. In conclusion, rapid decline in RRF over a 12-month period increased the risk of mortality and likewise anuria, beyond previously established risk factors for mortality and anuria. The impact on mortality and RRF preservation was particularly severe for those with diabetes mellitus. Copyright © 2017 International Society for Peritoneal Dialysis.

  19. Implantable cardioverter-defibrillators improve survival after coronary artery bypass grafting in patients with severely impaired left ventricular function

    Directory of Open Access Journals (Sweden)

    Pasque Michael K

    2007-01-01

    Full Text Available Abstract Objective Patients with severe left ventricular (LV dysfunction have a poor long term survival despite complete surgical revascularization. Recent data suggests that the use of Implantable Cardioverter-Defibrillator (ICD improves survival in patients with severe LV dysfunction. We compared the survival impact of ICD implantation in patients with severe LV dysfunction who underwent CABG. Methods Between January 1996 and August 2004, 305 patients with LV ejection fraction (EF ≤25% had CABG surgery at our institution. Demographics of patients who had received an ICD (ICD+ in the post -operative period was compared to those without ICD (ICD-. Survival was evaluated by the Kaplan-Meier method. Results Of the entire group, 35 (11.5% patients received an ICD with a median of 2 (+/-2 years after CABG. Indication for ICD implantation was clinical evidence of non sustained ventricular tachycardia (NSVT. There were no differences between the 2 groups with respect to age, gender, NYHA classification, number of bypasses, or other co-morbidities. Survival at 1, 3 and 5 years was 88%, 79%, and 67% for the ICD- group compared to 94%, 89% and 83% for the ICD+ group, respectively (figure, p Conclusion Implantation of ICD after CABG confers improved short and long term survival benefit to patients with severe LV dysfunction. Prophylactic ICD implantation in the setting of severe LV dysfunction and CABG surgery should be considered.

  20. Symptomatic spinal metastasis: A systematic literature review of the preoperative prognostic factors for survival, neurological, functional and quality of life in surgically treated patients and methodological recommendations for prognostic studies.

    Directory of Open Access Journals (Sweden)

    Anick Nater

    Full Text Available While several clinical prediction rules (CPRs of survival exist for patients with symptomatic spinal metastasis (SSM, these have variable prognostic ability and there is no recognized CPR for health related quality of life (HRQoL. We undertook a critical appraisal of the literature to identify key preoperative prognostic factors of clinical outcomes in patients with SSM who were treated surgically. The results of this study could be used to modify existing or develop new CPRs.Seven electronic databases were searched (1990-2015, without language restriction, to identify studies that performed multivariate analysis of preoperative predictors of survival, neurological, functional and HRQoL outcomes in surgical patients with SSM. Individual studies were assessed for class of evidence. The strength of the overall body of evidence was evaluated using GRADE for each predictor.Among 4,818 unique citations, 17 were included; all were in English, rated Class III and focused on survival, revealing a total of 46 predictors. The strength of the overall body of evidence was very low for 39 and low for 7 predictors. Due to considerable heterogeneity in patient samples and prognostic factors investigated as well as several methodological issues, our results had a moderately high risk of bias and were difficult to interpret.The quality of evidence for predictors of survival was, at best, low. We failed to identify studies that evaluated preoperative prognostic factors for neurological, functional, or HRQoL outcomes in surgical patients with SSM. We formulated methodological recommendations for prognostic studies to promote acquiring high-quality evidence to better estimate predictor effect sizes to improve patient education, surgical decision-making and development of CPRs.

  1. Assessment of pedotransfer functions for estimating soil water retention curves for the amazon region

    Directory of Open Access Journals (Sweden)

    João Carlos Medeiros

    2014-06-01

    Full Text Available Knowledge of the soil water retention curve (SWRC is essential for understanding and modeling hydraulic processes in the soil. However, direct determination of the SWRC is time consuming and costly. In addition, it requires a large number of samples, due to the high spatial and temporal variability of soil hydraulic properties. An alternative is the use of models, called pedotransfer functions (PTFs, which estimate the SWRC from easy-to-measure properties. The aim of this paper was to test the accuracy of 16 point or parametric PTFs reported in the literature on different soils from the south and southeast of the State of Pará, Brazil. The PTFs tested were proposed by Pidgeon (1972, Lal (1979, Aina & Periaswamy (1985, Arruda et al. (1987, Dijkerman (1988, Vereecken et al. (1989, Batjes (1996, van den Berg et al. (1997, Tomasella et al. (2000, Hodnett & Tomasella (2002, Oliveira et al. (2002, and Barros (2010. We used a database that includes soil texture (sand, silt, and clay, bulk density, soil organic carbon, soil pH, cation exchange capacity, and the SWRC. Most of the PTFs tested did not show good performance in estimating the SWRC. The parametric PTFs, however, performed better than the point PTFs in assessing the SWRC in the tested region. Among the parametric PTFs, those proposed by Tomasella et al. (2000 achieved the best accuracy in estimating the empirical parameters of the van Genuchten (1980 model, especially when tested in the top soil layer.

  2. Sensitivity analysis of point and parametric pedotransfer functions for estimating water retention of soils in Algeria

    Science.gov (United States)

    Touil, Sami; Degre, Aurore; Nacer Chabaca, Mohamed

    2016-12-01

    Improving the accuracy of pedotransfer functions (PTFs) requires studying how prediction uncertainty can be apportioned to different sources of uncertainty in inputs. In this study, the question addressed was as follows: which variable input is the main or best complementary predictor of water retention, and at which water potential? Two approaches were adopted to generate PTFs: multiple linear regressions (MLRs) for point PTFs and multiple nonlinear regressions (MNLRs) for parametric PTFs. Reliability tests showed that point PTFs provided better estimates than parametric PTFs (root mean square error, RMSE: 0.0414 and 0.0444 cm3 cm-3, and 0.0613 and 0.0605 cm3 cm-3 at -33 and -1500 kPa, respectively). The local parametric PTFs provided better estimates than Rosetta PTFs at -33 kPa. No significant difference in accuracy, however, was found between the parametric PTFs and Rosetta H2 at -1500 kPa with RMSE values of 0.0605 cm3 cm-3 and 0.0636 cm3 cm-3, respectively. The results of global sensitivity analyses (GSAs) showed that the mathematical formalism of PTFs and their input variables reacted differently in terms of point pressure and texture. The point and parametric PTFs were sensitive mainly to the sand fraction in the fine- and medium-textural classes. The use of clay percentage (C %) and bulk density (BD) as inputs in the medium-textural class improved the estimation of PTFs at -33 kPa.

  3. The Impact of Clinical and Cognitive Variables on Social Functioning in Parkinson's Disease: Patient versus Examiner Estimates

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    Patrick McNamara

    2010-01-01

    Results. Patients' estimates of their own social functioning were not significantly different from examiners' estimates. The impact of clinical variables on social functioning in PD revealed depression to be the strongest association of social functioning in PD on both the patient and the examiner version of the Social Adaptation Self-Evaluation Scale. Conclusions. PD patients appear to be well aware of their social strengths and weaknesses. Depression and motor symptom severity are significant predictors of both self- and examiner reported social functioning in patients with PD. Assessment and treatment of depression in patients with PD may improve social functioning and overall quality of life.

  4. Estimating Water Footprints of Vegetable Crops: Influence of Growing Season, Solar Radiation Data and Functional Unit

    Directory of Open Access Journals (Sweden)

    Betsie le Roux

    2016-10-01

    Full Text Available Water footprint (WF accounting as proposed by the Water Footprint Network (WFN can potentially provide important information for water resource management, especially in water scarce countries relying on irrigation to help meet their food requirements. However, calculating accurate WFs of short-season vegetable crops such as carrots, cabbage, beetroot, broccoli and lettuce presented some challenges. Planting dates and inter-annual weather conditions impact WF results. Joining weather datasets of just rainfall, minimum and maximum temperature with ones that include solar radiation and wind-speed affected crop model estimates and WF results. The functional unit selected can also have a major impact on results. For example, WFs according to the WFN approach do not account for crop residues used for other purposes, like composting and animal feed. Using yields in dry matter rather than fresh mass also impacts WF metrics, making comparisons difficult. To overcome this, using the nutritional value of crops as a functional unit can connect water use more directly to potential benefits derived from different crops and allow more straightforward comparisons. Grey WFs based on nitrogen only disregards water pollution caused by phosphates, pesticides and salinization. Poor understanding of the fate of nitrogen complicates estimation of nitrogen loads into the aquifer.

  5. Survival Analysis of Patients with End Stage Renal Disease

    Science.gov (United States)

    Urrutia, J. D.; Gayo, W. S.; Bautista, L. A.; Baccay, E. B.

    2015-06-01

    This paper provides a survival analysis of End Stage Renal Disease (ESRD) under Kaplan-Meier Estimates and Weibull Distribution. The data were obtained from the records of V. L. MakabaliMemorial Hospital with respect to time t (patient's age), covariates such as developed secondary disease (Pulmonary Congestion and Cardiovascular Disease), gender, and the event of interest: the death of ESRD patients. Survival and hazard rates were estimated using NCSS for Weibull Distribution and SPSS for Kaplan-Meier Estimates. These lead to the same conclusion that hazard rate increases and survival rate decreases of ESRD patient diagnosed with Pulmonary Congestion, Cardiovascular Disease and both diseases with respect to time. It also shows that female patients have a greater risk of death compared to males. The probability risk was given the equation R = 1 — e-H(t) where e-H(t) is the survival function, H(t) the cumulative hazard function which was created using Cox-Regression.

  6. Efficient Estimation of Dynamic Density Functions with Applications in Streaming Data

    KAUST Repository

    Qahtan, Abdulhakim

    2016-05-11

    Recent advances in computing technology allow for collecting vast amount of data that arrive continuously in the form of streams. Mining data streams is challenged by the speed and volume of the arriving data. Furthermore, the underlying distribution of the data changes over the time in unpredicted scenarios. To reduce the computational cost, data streams are often studied in forms of condensed representation, e.g., Probability Density Function (PDF). This thesis aims at developing an online density estimator that builds a model called KDE-Track for characterizing the dynamic density of the data streams. KDE-Track estimates the PDF of the stream at a set of resampling points and uses interpolation to estimate the density at any given point. To reduce the interpolation error and computational complexity, we introduce adaptive resampling where more/less resampling points are used in high/low curved regions of the PDF. The PDF values at the resampling points are updated online to provide up-to-date model of the data stream. Comparing with other existing online density estimators, KDE-Track is often more accurate (as reflected by smaller error values) and more computationally efficient (as reflected by shorter running time). The anytime available PDF estimated by KDE-Track can be applied for visualizing the dynamic density of data streams, outlier detection and change detection in data streams. In this thesis work, the first application is to visualize the taxi traffic volume in New York city. Utilizing KDE-Track allows for visualizing and monitoring the traffic flow on real time without extra overhead and provides insight analysis of the pick up demand that can be utilized by service providers to improve service availability. The second application is to detect outliers in data streams from sensor networks based on the estimated PDF. The method detects outliers accurately and outperforms baseline methods designed for detecting and cleaning outliers in sensor data. The

  7. Estimation of the global inventory of methane hydrates in marine sediments using transfer functions

    Directory of Open Access Journals (Sweden)

    E. Piñero

    2013-02-01

    Full Text Available The accumulation of gas hydrates in marine sediments is essentially controlled by the accumulation of particulate organic carbon (POC which is microbially converted into methane, the thickness of the gas hydrate stability zone (GHSZ where methane can be trapped, the sedimentation rate (SR that controls the time that POC and the generated methane stays within the GHSZ, and the delivery of methane from deep-seated sediments by ascending pore fluids and gas into the GHSZ. Recently, Wallmann et al. (2012 presented transfer functions to predict the gas hydrate inventory in diffusion-controlled geological systems based on SR, POC and GHSZ thickness for two different scenarios: normal and full compacting sediments. We apply these functions to global data sets of bathymetry, heat flow, seafloor temperature, POC input and SR, estimating a global mass of carbon stored in marine methane hydrates from 3 to 455 Gt of carbon (GtC depending on the sedimentation and compaction conditions. The global sediment volume of the GHSZ in continental margins is estimated to be 60–67 × 1015 m3, with a total of 7 × 1015 m3 of pore volume (available for GH accumulation. However, seepage of methane-rich fluids is known to have a pronounced effect on gas hydrate accumulation. Therefore, we carried out a set of systematic model runs with the transport-reaction code in order to derive an extended transfer function explicitly considering upward fluid advection. Using averaged fluid velocities for active margins, which were derived from mass balance considerations, this extended transfer function predicts the enhanced gas hydrate accumulation along the continental margins worldwide. Different scenarios were investigated resulting in a global mass of sub-seafloor gas hydrates of ~ 550 GtC. Overall, our systematic approach allows to clearly and quantitatively distinguish between the effect of biogenic methane generation from POC and

  8. Microbes in nature are limited by carbon and energy: the starving-survival lifestyle in soil and consequences for estimating microbial rates

    Directory of Open Access Journals (Sweden)

    John Eyres Hobbie

    2013-11-01

    Full Text Available Understanding microbial transformations in soils is important for predicting future carbon sequestration and nutrient cycling. This review questions some methods of assessing one key microbial process, the uptake of labile organic compounds. First, soil microbes have a starving-survival life style of dormancy, arrested activity, and low activity. Yet they are very abundant and remain poised to completely take up all substrates that become available. As a result, dilution assays with the addition of labeled substrates cannot be used. When labeled substrates are transformed into 14CO2, the first part of the biphasic release follows metabolic rules and is not affected by the environment. As a consequence, when identical amounts of isotopically substrates are added to soils from different climate zones, the same percentage of the substrate is respired and the same half-life of the respired 14CO2 from the labeled substrate is estimated. Second, when soils are sampled by a variety of methods from taking 10 cm diameter cores to millimeter-scale dialysis chambers, amino acids (and other organic compounds appear to be released by the severing of fine roots and mycorrhizal networks as well as from pressing or centrifuging treatments. As a result of disturbance as well as of natural root release, concentrations of individual amino acids of ~10 µM are measured. This contrasts with concentrations of a few nM found in aquatic systems and raises questions about possible differences in the bacterial strategy between aquatic and soil ecosystems. The small size of the hyphae (2-10 μm diameter and of the fine roots (0.2 to 2 mm diameter, make it very difficult to sample any volume of soil without introducing artifacts. Third, when micromolar amounts of labeled amino acids are added to soil, some of the isotope enters plant roots. This may be an artifact of the high µM concentrations applied.

  9. Association of estimated glomerular filtration rate with muscle function in older persons who have fallen.

    Science.gov (United States)

    Tap, Lisanne; Boyé, Nicole D A; Hartholt, Klaas A; van der Cammen, Tischa J M; Mattace-Raso, Francesco U S

    2018-03-01

    studies suggest that estimated glomerular filtration rate (eGFR) is less reliable in older persons and that a low serum-creatinine might reflect reduced muscle mass rather than high kidney function. This study investigates the possible relationship between eGFR and multiple elements of physical performance in older fallers. baseline data of the IMPROveFALL-study were examined in participants ≥65 years. Serum-creatinine based eGFR was classified as normal (≥90 ml/min), mildly reduced (60-89 ml/min) or moderately-severely reduced (<60 ml/min). Timed-Up-and-Go-test and Five-Times-Sit-to-Stand-test were used to assess mobility; calf circumference and handgrip strength to assess muscle status. Ancova models adjusted for age, sex, Charlson comorbidity index and body mass index were performed. a total of 578 participants were included. Participants with a normal eGFR had lower handgrip strength than those with a mildly reduced eGFR (-9.5%, P < 0.001) and those with a moderately-severely reduced eGFR (-6.3%, P = 0.033) with mean strengths of 23.4, 25.8 and 24.9 kg, respectively. Participants with a normal eGFR had a smaller calf circumference than those with a mildly reduced eGFR (35.5 versus 36.5 cm, P = 0.006). Mean time to complete the mobility tests did not differ. in this study we found that older fallers with an eGFR ≥ 90 ml/min had smaller calf circumference and up to 10% lower handgrip strength than those with a reduced eGFR. This lower muscle mass is likely to lead to an overestimation of kidney function. This outcome therefore supports the search for biomarkers independent of muscle mass to estimate kidney function in older persons.

  10. Mapping functional traits: comparing abundance and presence-absence estimates at large spatial scales.

    Directory of Open Access Journals (Sweden)

    Tim Newbold

    Full Text Available Efforts to quantify the composition of biological communities increasingly focus on functional traits. The composition of communities in terms of traits can be summarized in several ways. Ecologists are beginning to map the geographic distribution of trait-based metrics from various sources of data, but the maps have not been tested against independent data. Using data for birds of the Western Hemisphere, we test for the first time the most commonly used method for mapping community trait composition - overlaying range maps, which assumes that the local abundance of a given species is unrelated to the traits in question - and three new methods that as well as the range maps include varying degrees of information about interspecific and geographic variation in abundance. For each method, and for four traits (body mass, generation length, migratory behaviour, diet we calculated community-weighted mean of trait values, functional richness and functional divergence. The maps based on species ranges and limited abundance data were compared with independent data on community species composition from the American Christmas Bird Count (CBC scheme coupled with data on traits. The correspondence with observed community composition at the CBC sites was mostly positive (62/73 correlations but varied widely depending on the metric of community composition and method used (R(2: 5.6 × 10(-7 to 0.82, with a median of 0.12. Importantly, the commonly-used range-overlap method resulted in the best fit (21/22 correlations positive; R(2: 0.004 to 0.8, with a median of 0.33. Given the paucity of data on the local abundance of species, overlaying range maps appears to be the best available method for estimating patterns of community composition, but the poor fit for some metrics suggests that local abundance data are urgently needed to allow more accurate estimates of the composition of communities.

  11. Methow River Studies, Washington: abundance estimates from Beaver Creek and the Chewuch River screw trap, methodology testing in the Whitefish Island side channel, and survival and detection estimates from hatchery fish releases, 2013

    Science.gov (United States)

    Martens, Kyle D.; Fish, Teresa M.; Watson, Grace A.; Connolly, Patrick J.

    2014-01-01

    , leaving one large pool near the bottom of the side channel and several shallow isolated pools that may or may not go dry. In seasonally connected side channels, juvenile salmonid survival in pools less than 100 cm average depth was lower than in pools greater than 100 cm average depth (Martens and Connolly, 2014). In this report, we document our field work and analysis completed in 2013. During 2013, USGS sampling efforts were focused on resampling of three reaches in Beaver Creek, testing methodology in the Whitefish Island side channel, conducting hatchery survival estimates, and operating a screw trap on the Chewuch River (funded by Yakama Nation; fig. 1). The Beaver Creek sampling effort was a revisit of three index sites sampled continuously from 2004 to 2007 to look at the fish response to barrier removal. Methodology testing in Whitefish Island side channel was done to determine the best method for evaluating fish populations after restoration efforts in side channels (previous sampling methods were determined to be ineffective after pools were deepened). Hatchery survival estimates were completed to monitor fish survival in the Methow and Columbia Rivers, while the screw trap was operated to estimate migrating fish populations in the Chewuch River and track passive integrated transponder (PIT)-tagged fish. In addition, we maintained a network of PIT-tag interrogation systems (PTIS), assisted Reclamation with fish removal events associated with stream restoration (two people for 9 days; 14 percent of summer field season), and conducted a stream metabolism study designed to help parameterize and calibrate the stream productivity model (Bellmore and others, 2014) with model validation.

  12. Executive Functions Brain System: An Activation Likelihood Estimation Meta-analytic Study.

    Science.gov (United States)

    Ardila, Alfredo; Bernal, Byron; Rosselli, Monica

    2017-09-11

    To characterize commonalities and differences between two executive functions: reasoning and inhibitory control. A total of 5,974 participants in 346 fMRI experiments of inhibition or reasoning were selected. First level analysis consisted of Analysis of Likelihood Estimation (ALE) studies performed in two pooled data groups: (a) brain areas involved in reasoning and (b) brain areas involved in inhibition. Second level analysis consisted of two contrasts: (i) brain areas involved in reasoning but not in inhibition and (ii) brain areas involved in inhibition but not in reasoning. Lateralization Indexes were calculated. Four brain areas appear as the most critical: the dorsolateral aspect of the frontal lobes, the superior parietal lobules, the mesial aspect of the premotor area (supplementary motor area), and some subcortical areas, particularly the putamen and the thalamus. ALE contrasts showed significant differentiation of the networks, with the reasoning > inhibition-contrast showing a predominantly leftward participation, and the inhibition > reasoning-contrast, a clear right advantage. Executive functions are mediated by sizable brain areas including not only cortical, but also involving subcortical areas in both hemispheres. The strength of activation shows dissociation between the hemispheres for inhibition (rightward) and reasoning (leftward) functions.

  13. Immediate loading of implants in the maxilla: survival and bone loss after at least 2 years in function.

    Science.gov (United States)

    Vervaeke, Stijn; Collaert, Bruno; De Bruyn, Hugo

    2013-01-01

    To compare survival and peri-implant bone loss around immediately loaded surface-enhanced implants in the maxilla supporting single crowns (SCs), fixed partial dentures (FPDs), and fixed full-arch dentures (FFDs). The study included all subjects referred for implant treatment in the maxilla followed by immediate loading between November 2004 and 2007 with at least 2 years of follow-up. Smokers were excluded. Implant survival and bone loss were assessed by a calibrated external examiner who compared digital periapical radiographs taken during recall visits with baseline radiographs (day of loading = day after implant placement). An implant was considered successful when bone loss did not exceed 1 mm. Survival of implants supporting SCs, FPDs, and FFDs was compared using the log-rank test. A linear mixed-effect model analysis was used to evaluate bone loss because of clustering of implants in patients. Three hundred six implants were placed in 55 patients (31 women, 24 men; mean age, 57.5 ± 11.4 years; range, 19 to 77 years) and followed for a mean of 35 ± 10.2 months (range, 24 to 58 months). One implant failed, resulting in an overall survival rate of 99.7% on the implant level and 98.2% on the patient level. No statistically significant differences were observed in the survival rates for SCs (100%), FPDs (98%), and FFDs (100%). The overall mean bone loss was 0.27 ± 0.37 mm (range, 0.00 to 2.55 mm) and was not influenced by the prosthetic reconstruction. Immediate loading of fluoride-modified implants in the maxilla is a predictable and reliable treatment option with high survival rates and limited peri-implant bone loss after 2 years. No statistically significant differences were found between implants supporting SCs, FPDs, and FFDs.

  14. Postoperative survival and functional outcomes for patients with metastatic gynecological cancer to the spine: case series and review of the literature.

    Science.gov (United States)

    Liu, Ann; Sankey, Eric W; Goodwin, C Rory; Kosztowski, Thomas A; Elder, Benjamin D; Bydon, Ali; Witham, Timothy F; Wolinsky, Jean-Paul; Gokaslan, Ziya L; Sciubba, Daniel M

    2016-01-01

    Spinal metastases from gynecological cancers are rare, with few cases reported in the literature. In this study, the authors examine a series of patients with spinal metastases from gynecological cancer and review the literature. The cases of 6 consecutive patients who underwent spine surgery for metastatic gynecological cancer between 2007 and 2012 at a single institution were retrospectively reviewed. The recorded demographic, operative, and postoperative factors were reviewed, and the functional outcomes were determined by change in Karnofsky Performance Scale and the American Spine Injury Association (ASIA) score during follow-up. A systematic review of the literature was also performed to evaluate outcomes for patients with similar gynecological metastases to the spine. In this series, details regarding metastatic gynecological cancers to the spine are as follows: 2 patients with cervical cancer (both presented at age 46 years, mean postoperative survival of 32 months), 2 patients with endometrial cancer (mean age of 40 years, mean postoperative survival of 26 months), and 2 patients with leiomyosarcoma (mean age of 44 years, mean postoperative survival of 20 months). All patients presented with pain, and no complications were noted following surgery. All patients with known follow-up had stable or improved neurological outcomes, performance status, and improved pain, without local recurrence of tumor. Overall median survival after diagnosis of metastatic spine lesions for all cases in the literature as well as those treated by the authors was 15 months. When categorized by type, median survival of patients with cervical cancer (n = 2), endometrial cancer (n = 26), and leiomyosarcoma (n = 16) was 32, 10, and 22.5 months, respectively. Gynecological cancers metastasizing to the spine are rare. In this series, overall survival following diagnosis of spinal metastasis and surgery was 27 months, with cervical cancer, endometrial cancer, and leiomyosarcoma survival

  15. Sensitivity of landscape resistance estimates based on point selection functions to scale and behavioral state: Pumas as a case study

    Science.gov (United States)

    Katherine A. Zeller; Kevin McGarigal; Paul Beier; Samuel A. Cushman; T. Winston Vickers; Walter M. Boyce

    2014-01-01

    Estimating landscape resistance to animal movement is the foundation for connectivity modeling, and resource selection functions based on point data are commonly used to empirically estimate resistance. In this study, we used GPS data points acquired at 5-min intervals from radiocollared pumas in southern California to model context-dependent point selection...

  16. Joint Bayesian Estimation of Quasar Continua and the Lyα Forest Flux Probability Distribution Function

    Science.gov (United States)

    Eilers, Anna-Christina; Hennawi, Joseph F.; Lee, Khee-Gan

    2017-08-01

    We present a new Bayesian algorithm making use of Markov Chain Monte Carlo sampling that allows us to simultaneously estimate the unknown continuum level of each quasar in an ensemble of high-resolution spectra, as well as their common probability distribution function (PDF) for the transmitted Lyα forest flux. This fully automated PDF regulated continuum fitting method models the unknown quasar continuum with a linear principal component analysis (PCA) basis, with the PCA coefficients treated as nuisance parameters. The method allows one to estimate parameters governing the thermal state of the intergalactic medium (IGM), such as the slope of the temperature-density relation γ -1, while marginalizing out continuum uncertainties in a fully Bayesian way. Using realistic mock quasar spectra created from a simplified semi-numerical model of the IGM, we show that this method recovers the underlying quasar continua to a precision of ≃ 7 % and ≃ 10 % at z = 3 and z = 5, respectively. Given the number of principal component spectra, this is comparable to the underlying accuracy of the PCA model itself. Most importantly, we show that we can achieve a nearly unbiased estimate of the slope γ -1 of the IGM temperature-density relation with a precision of +/- 8.6 % at z = 3 and +/- 6.1 % at z = 5, for an ensemble of ten mock high-resolution quasar spectra. Applying this method to real quasar spectra and comparing to a more realistic IGM model from hydrodynamical simulations would enable precise measurements of the thermal and cosmological parameters governing the IGM, albeit with somewhat larger uncertainties, given the increased flexibility of the model.

  17. Pedotransfer functions to estimate bulk density from soil properties and environmental covariates: Rio Doce basin

    Directory of Open Access Journals (Sweden)

    Eliana de Souza

    Full Text Available ABSTRACT Soil bulk density (ρb data are needed for a wide range of environmental studies. However, ρb is rarely reported in soil surveys. An alternative to obtain ρb for data-scarce regions, such as the Rio Doce basin in southeastern Brazil, is indirect estimation from less costly covariates using pedotransfer functions (PTF. This study primarily aims to develop region-specific PTFs for ρb using multiple linear regressions (MLR and random forests (RF. Secondly, it assessed the accuracy of PTFs for data grouped into soil horizons and soil classes. For that purpose, we compared the performance of PTFs compiled from the literature with those developed here. Two groups of data were evaluated as covariates: 1 readily available soil properties and 2 maps derived from a digital elevation model and MODIS satellite imagery, jointly with lithological and pedological maps. The MLR model was applied step-wise to select significant predictors and its accuracy assessed by means of cross-validation. The PTFs developed using all data estimated ρb from soil properties by MLR and RF, with R2 of 0.41 and 0.51, respectively. Alternatively, using environmental covariates, RF predicted ρb with R2 of 0.41. Grouping criteria did not lead to a significant increase in the estimates of ρb. The accuracy of the ‘regional’ PTFs developed for this study was greater than that found with the ‘compiled’ PTFs. The best PTF will be firstly used to assess soil carbon stocks and changes in the Rio Doce basin.

  18. Association analysis of insulin-like growth factor-1 axis parameters with survival and functional status in nonagenarians of the Leiden Longevity Study

    DEFF Research Database (Denmark)

    van der Spoel, Evie; Rozing, Maarten P; Houwing-Duistermaat, Jeanine J

    2015-01-01

    Reduced insulin/insulin-like growth factor 1 (IGF-1) signaling has been associated with longevity in various model organisms. However, the role of insulin/IGF-1 signaling in human survival remains controversial. The aim of this study was to test whether circulating IGF-1 axis parameters associate...... with old age survival and functional status in nonagenarians from the Leiden Longevity Study. This study examined 858 Dutch nonagenarian (males≥89 years; females≥91 years) siblings from 409 families, without selection on health or demographic characteristics. Nonagenarians were divided over sex.......91) compared to the quartile with the highest ratio (ptrend=0.002). Functional status was assessed by (Instrumental) Activities of Daily Living ((I)ADL) scales. Compared to those in the quartile with the highest IGF-1/IGFBP3 ratio, nonagenarians in the lowest quartile had higher scores for ADL (ptrend=0...

  19. Hemodynamic response based mixture model to estimate micro- and macro-vasculature contributions in functional MRI

    CERN Document Server

    Singh, Manbir; Sungkarat, Witaya; Zhou, Yongxia

    2003-01-01

    A multi-componet model reflecting the temporal characteristics of micro- and macro-vasculature hemodynamic responses was used to fit the time-course of voxels in functional MRI (fMRI). The number of relevant components, the latency of the first component, the time- separation among the components, their relative amplitude and possible interpretation in terms of partial volume contributions of micro- and macro-components to the time-course data were investigated. Analysis of a reversing checkerboard experiment revealed that there was no improvement in the filing beyond two components. Using a two-component model, the fractional abundances of the micro- and macro-vasculature were estimated in individual voxels. These results suggest the potential of a mixture-model approach to mitigate partial volume effects and separate contributions of vascular components within a voxel in fMRI.

  20. Estimating genetic covariance functions assuming a parametric correlation structure for environmental effects

    Directory of Open Access Journals (Sweden)

    Meyer Karin

    2001-11-01

    Full Text Available Abstract A random regression model for the analysis of "repeated" records in animal breeding is described which combines a random regression approach for additive genetic and other random effects with the assumption of a parametric correlation structure for within animal covariances. Both stationary and non-stationary correlation models involving a small number of parameters are considered. Heterogeneity in within animal variances is modelled through polynomial variance functions. Estimation of parameters describing the dispersion structure of such model by restricted maximum likelihood via an "average information" algorithm is outlined. An application to mature weight records of beef cow is given, and results are contrasted to those from analyses fitting sets of random regression coefficients for permanent environmental effects.

  1. Spectral Velocity Estimation using the Autocorrelation Function and Sparse data Sequences

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2005-01-01

    of the sequence. The audio signal has also been synthesized from the autocorrelation data by passing white, Gaussian noise through a filter designed from the power spectrum of the autocorrelation function. The results show that both the full velocity range can be maintained at the same time as a B-mode image......Ultrasound scanners can be used for displaying the distribution of velocities in blood vessels by finding the power spectrum of the received signal. It is desired to show a B-mode image for orientation and data for this has to be acquired interleaved with the flow data. Techniques for maintaining......, be used for estimating $R_r(k)$. The approach has been investigated using Field II simulation of the flow in the carotid and femoral arteries. A 5 MHz linear array transducer with 128 elements, a pitch of $\\lambda$ and an element height of 5 mm was simulated. The autocorrelation was calculated from...

  2. Effect of Anisotropic Yield Function Evolution on Estimation of Forming Limit Diagram

    Science.gov (United States)

    Bandyopadhyay, K.; Basak, S.; Choi, H. J.; Panda, S. K.; Lee, M. G.

    2017-09-01

    In case of theoretical prediction of the FLD, the variations in yield stress and R-values along different material directions, were long been implemented to enhance the accuracy. Although influences of different yield models and hardening laws on formability were well addressed, anisotropic evolution of yield loci under monotonic loading with different deformation modes is yet to be explored. In the present study, Marciniak-Kuckzinsky (M-K) model was modified to incorporate the change in the shape of the initial yield function with evolution due to anisotropic hardening. Swift’s hardening law along with two different anisotropic yield criteria, namely Hill48 and Yld2000-2d were implemented in the model. The Hill48 yield model was applied with non-associated flow rule to comprehend the effect of variations in both yield stress and R-values. The numerically estimated FLDs were validated after comparing with FLD evaluated through experiments. A low carbon steel was selected, and hemispherical punch stretching test was performed for FLD evaluation. Additionally, the numerically estimated FLDs were incorporated in FE simulations to predict limiting dome heights for validation purpose. Other formability performances like strain distributions over the deformed cup surface were validated with experimental results.

  3. Efficient estimation and prediction for the Bayesian binary spatial model with flexible link functions.

    Science.gov (United States)

    Roy, Vivekananda; Evangelou, Evangelos; Zhu, Zhengyuan

    2016-03-01

    Spatial generalized linear mixed models (SGLMMs) are popular models for spatial data with a non-Gaussian response. Binomial SGLMMs with logit or probit link functions are often used to model spatially dependent binomial random variables. It is known that for independent binomial data, the robit regression model provides a more robust (against extreme observations) alternative to the more popular logistic and probit models. In this article, we introduce a Bayesian spatial robit model for spatially dependent binomial data. Since constructing a meaningful prior on the link function parameter as well as the spatial correlation parameters in SGLMMs is difficult, we propose an empirical Bayes (EB) approach for the estimation of these parameters as well as for the prediction of the random effects. The EB methodology is implemented by efficient importance sampling methods based on Markov chain Monte Carlo (MCMC) algorithms. Our simulation study shows that the robit model is robust against model misspecification, and our EB method results in estimates with less bias than full Bayesian (FB) analysis. The methodology is applied to a Celastrus Orbiculatus data, and a Rhizoctonia root data. For the former, which is known to contain outlying observations, the robit model is shown to do better for predicting the spatial distribution of an invasive species. For the latter, our approach is doing as well as the classical models for predicting the disease severity for a root disease, as the probit link is shown to be appropriate. Though this article is written for Binomial SGLMMs for brevity, the EB methodology is more general and can be applied to other types of SGLMMs. In the accompanying R package geoBayes, implementations for other SGLMMs such as Poisson and Gamma SGLMMs are provided. © 2015, The International Biometric Society.

  4. Estimating dollar-value outcomes of workman`s compensation claims using radial basis function networks

    Energy Technology Data Exchange (ETDEWEB)

    Hancock, M.F. Jr. [Rollins College, Winter Park, FL (United States)

    1995-12-31

    The National Council on Compensation Insurance (NCCI) maintains a national data base of outcomes of workers` compensation claims. We consider whether a radial basis function network can predict the total dollar value of a claim based upon medical and demographic indicators (MDI`s). This work used data from 12,130 workers` compensation claims collected over a period of four years from the state of New Mexico. Two problems were addressed: (1) How well can the total incurred medical expense for all claims be predicted from available MDI`s? For individual claims? (2) How well can the duration of disability be predicted from available MDI`s? The available features intuitively correlated with total medical cost were selected, including type of injury, part of body injured, person`s age at time of injury, gender, marital status, etc. These features were statistically standardized and sorted by correlation with outcome valuation. Principal component analysis was applied. A radial basis function neural network was applied to the feature sets in both supervised and unsupervised training modes. For sets used in training, individual case valuations could consistently be predicted to within $1000 over 98% of the time. For these sets, it was possible to predict total medical expense for the training sets themselves to within 10%. When applied as blind tests against sets which were NOT part of the training data, the prediction was within 15% on the whole sets. Results on individual cases were very poor in only 30% of the cases were the predictions for the training sets within $1000 of their actual valuations. Single-factor analysis suggested that the presence of an attorney strongly decorrelated the data. A simple stratification was performed to remove cases involving attorneys and contested claims, and the procedures above repeated. Preliminary results based upon the very limited effort applied indicate that NCCI data support population estimates, but not single-point estimates.

  5. Relationship between somatic cell count and functional longevity assessed using survival analysis in Italian Holstein-Friesian cows

    NARCIS (Netherlands)

    Samoré, A.B.; Schneider, M.D.P.; Canavesi, F.; Bagnato, A.; Groen, A.F.

    2003-01-01

    The relationship between somatic cell scores (SCS) and longevity was assessed for Italian Holstein–Friesian dairy cows using survival analysis. The data of somatic cell count (SCC) test day information of 512 979 cows were provided by nine provinces from Northern Italy. Pedigree information was

  6. Inverse modelling in estimating soil hydraulic functions: a Genetic Algorithm approach

    Directory of Open Access Journals (Sweden)

    A. V. M. Ines

    2002-01-01

    Full Text Available The practical application of simulation models in the field is sometimes hindered by the difficulty of deriving the soil hydraulic properties of the study area. The procedure so-called inverse modelling has been investigated in many studies to address the problem where most of the studies were limited to hypothetical soil profile and soil core samples in the laboratory. Often, the numerical approach called forward-backward simulation is employed to generate synthetic data then added with random errors to mimic the real-world condition. Inverse modelling is used to backtrack the expected values of the parameters. This study explored the potential of a Genetic Algorithm (GA to estimate inversely the soil hydraulic functions in the unsaturated zone. Lysimeter data from a wheat experiment in India were used in the analysis. Two cases were considered: (1 a numerical case where the forward-backward approach was employed and (2 the experimental case where the real data from the lysimeter experiment were used. Concurrently, the use of soil water, evapotranspiration (ET and the combination of both were investigated as criteria in the inverse modelling. Results showed that using soil water as a criterion provides more accurate parameter estimates than using ET. However, from a practical point of view, ET is more attractive as it can be obtained with reasonable accuracy on a regional scale from remote sensing observations. The experimental study proved that the forward-backward approach does not take into account the effects of model errors. The formulation of the problem is found to be critical for a successful parameter estimation. The sensitivity of parameters to the objective function and their zone of influence in the soil column are major determinants in the solution. Generally, their effects sometimes lead to non-uniqueness in the solution but to some extent are partly handled by GA. Overall, it was concluded that the GA approach is promising to the

  7. Quantitative Functional Imaging Using Dynamic Positron Computed Tomography and Rapid Parameter Estimation Techniques

    Science.gov (United States)

    Koeppe, Robert Allen

    Positron computed tomography (PCT) is a diagnostic imaging technique that provides both three dimensional imaging capability and quantitative measurements of local tissue radioactivity concentrations in vivo. This allows the development of non-invasive methods that employ the principles of tracer kinetics for determining physiological properties such as mass specific blood flow, tissue pH, and rates of substrate transport or utilization. A physiologically based, two-compartment tracer kinetic model was derived to mathematically describe the exchange of a radioindicator between blood and tissue. The model was adapted for use with dynamic sequences of data acquired with a positron tomograph. Rapid estimation techniques were implemented to produce functional images of the model parameters by analyzing each individual pixel sequence of the image data. A detailed analysis of the performance characteristics of three different parameter estimation schemes was performed. The analysis included examination of errors caused by statistical uncertainties in the measured data, errors in the timing of the data, and errors caused by violation of various assumptions of the tracer kinetic model. Two specific radioindicators were investigated. ('18)F -fluoromethane, an inert freely diffusible gas, was used for local quantitative determinations of both cerebral blood flow and tissue:blood partition coefficient. A method was developed that did not require direct sampling of arterial blood for the absolute scaling of flow values. The arterial input concentration time course was obtained by assuming that the alveolar or end-tidal expired breath radioactivity concentration is proportional to the arterial blood concentration. The scale of the input function was obtained from a series of venous blood concentration measurements. The method of absolute scaling using venous samples was validated in four studies, performed on normal volunteers, in which directly measured arterial concentrations

  8. Improving the estimation of psychometric functions in 2AFC discrimination tasks

    Directory of Open Access Journals (Sweden)

    Miguel A García-Pérez

    2011-05-01

    Full Text Available Ulrich and Vorberg (2009 presented a method that fits distinct functions for each order of presentation of standard and test stimuli in a 2AFC discrimination task, which removes the contaminating influence of order effects from estimates of the difference limen. The two functions are fitted simultaneously under the constraint that their average evaluates to .5 when test and standard have the same magnitude, which was regarded as a general property of 2AFC tasks. This constraint implies that physical identity produces indistinguishability, which is valid when test and standard are identical except for magnitude along the dimension of comparison. However, indistinguishability does not occur at physical identity when test and standard differ on dimensions other than that along which they are compared (e.g., vertical and horizontal lines of the same length are not perceived to have the same length. In these cases, the method of Ulrich and Vorberg cannot be used. We propose a generalization of their method for use in such cases and illustrate it with data from a 2AFC experiment involving length discrimination of horizontal and vertical lines. The resultant data could be fitted with our generalization but not with the method of Ulrich and Vorberg. Further extensions of this method are discussed.

  9. Improving the estimation of psychometric functions in 2AFC discrimination tasks.

    Science.gov (United States)

    García-Pérez, Miguel A; Alcalá-Quintana, Rocío

    2011-01-01

    Ulrich and Vorberg (2009) presented a method that fits distinct functions for each order of presentation of standard and test stimuli in a two-alternative forced-choice (2AFC) discrimination task, which removes the contaminating influence of order effects from estimates of the difference limen. The two functions are fitted simultaneously under the constraint that their average evaluates to 0.5 when test and standard have the same magnitude, which was regarded as a general property of 2AFC tasks. This constraint implies that physical identity produces indistinguishability, which is valid when test and standard are identical except for magnitude along the dimension of comparison. However, indistinguishability does not occur at physical identity when test and standard differ on dimensions other than that along which they are compared (e.g., vertical and horizontal lines of the same length are not perceived to have the same length). In these cases, the method of Ulrich and Vorberg cannot be used. We propose a generalization of their method for use in such cases and illustrate it with data from a 2AFC experiment involving length discrimination of horizontal and vertical lines. The resultant data could be fitted with our generalization but not with the method of Ulrich and Vorberg. Further extensions of this method are discussed.

  10. SURVIVAL ANALYSIS AND LENGTH-BIASED SAMPLING

    Directory of Open Access Journals (Sweden)

    Masoud Asgharian

    2010-12-01

    Full Text Available When survival data are colleted as part of a prevalent cohort study, the recruited cases have already experienced their initiating event. These prevalent cases are then followed for a fixed period of time at the end of which the subjects will either have failed or have been censored. When interests lies in estimating the survival distribution, from onset, of subjects with the disease, one must take into account that the survival times of the cases in a prevalent cohort study are left truncated. When it is possible to assume that there has not been any epidemic of the disease over the past period of time that covers the onset times of the subjects, one may assume that the underlying incidence process that generates the initiating event times is a stationary Poisson process. Under such assumption, the survival times of the recrui