Trunk Muscle Attributes are Associated with Balance and Mobility in Older Adults: A Pilot Study

PubMed Central

Suri, Pradeep; Kiely, Dan K.; Leveille, Suzanne G.; Frontera, Walter R.; Bean, Jonathan. F.

2010-01-01

Objective To determine if trunk muscle attributes are associated with balance and mobility performance among mobility-limited older adults. Design Cross-sectional analysis of data from a randomized clinical trial. Setting Outpatient rehabilitation research center. Participants Community-dwelling older adults (N=70; mean age 75.9 y) with mobility limitations as defined by the Short Physical Performance Battery (SPPB). Methods Independent variables included physiologic measures of trunk extension strength, trunk flexion strength, trunk extension endurance, trunk extension endurance and leg press strength. All measures were well tolerated by the study subjects without the occurrence of any associated injuries or adverse events. The association of each physiologic measure with each outcome was examined, using separate multivariate models to calculate the partial variance (R2) of each trunk and extremity measure. Main Outcome Measurements Balance measured by the Berg Balance Scale (BBS) and Unipedal Stance Test (UST), and mobility performance as measured by the SPPB. Results Trunk extension endurance (partial R2=.14, p=.02), and leg press strength (partial R2=.14, p=.003) accounted for the greatest amount of the variance in SPPB performance. Trunk extension endurance (partial R2=.17, p=.007), accounted for the greatest amount of the variance in BBS performance. Trunk extension strength (R2=.09, p=.03), accounted for the greatest amount of the variance in UST performance. The variance explained by trunk extension endurance equaled or exceeded the variance explained by limb strength across all three performance outcomes. Conclusions Trunk endurance and strength can be safely measured in mobility-limited older adults, and are associated with both balance and mobility performance. Trunk endurance and trunk strength are physiologic attributes worthy of targeting in the rehabilitative care of mobility-limited older adults. PMID:19854420

Trunk muscle attributes are associated with balance and mobility in older adults: a pilot study.

PubMed

Suri, Pradeep; Kiely, Dan K; Leveille, Suzanne G; Frontera, Walter R; Bean, Jonathan F

2009-10-01

To determine whether trunk muscle attributes are associated with balance and mobility performance among mobility-limited older adults. Cross-sectional analysis of data from a randomized clinical trial. Outpatient rehabilitation research center. Community-dwelling older adults (N = 70; mean age 75.9 years) with mobility limitations as defined by the Short Physical Performance Battery (SPPB). Independent variables included physiologic measures of trunk extension strength, trunk flexion strength, trunk extension endurance, trunk extension endurance, and leg press strength. All measures were well tolerated by the study subjects without the occurrence of any associated injuries or adverse events. The association of each physiologic measure with each outcome was examined by the use of separate multivariate models to calculate the partial variance (R(2)) of each trunk and extremity measure. Balance measured by the Berg Balance Scale and Unipedal Stance Test and mobility performance as measured by the SPPB. Trunk extension endurance (partial R(2) = .14, P = .02), and leg press strength (partial R(2) = .14, P = .003) accounted for the greatest amount of the variance in SPPB performance. Trunk extension endurance (partial R(2) = .17, P = .007), accounted for the greatest amount of the variance in BBS performance. Trunk extension strength (R(2) = .09, P = .03), accounted for the greatest amount of the variance in UST performance. The variance explained by trunk extension endurance equaled or exceeded the variance explained by limb strength across all three performance outcomes. Trunk endurance and strength can be safely measured in mobility-limited older adults and are associated with both balance and mobility performance. Trunk endurance and trunk strength are physiologic attributes worthy of targeting in the rehabilitative care of mobility-limited older adults.

Robust analysis of semiparametric renewal process models

PubMed Central

Lin, Feng-Chang; Truong, Young K.; Fine, Jason P.

2013-01-01

Summary A rate model is proposed for a modulated renewal process comprising a single long sequence, where the covariate process may not capture the dependencies in the sequence as in standard intensity models. We consider partial likelihood-based inferences under a semiparametric multiplicative rate model, which has been widely studied in the context of independent and identical data. Under an intensity model, gap times in a single long sequence may be used naively in the partial likelihood with variance estimation utilizing the observed information matrix. Under a rate model, the gap times cannot be treated as independent and studying the partial likelihood is much more challenging. We employ a mixing condition in the application of limit theory for stationary sequences to obtain consistency and asymptotic normality. The estimator's variance is quite complicated owing to the unknown gap times dependence structure. We adapt block bootstrapping and cluster variance estimators to the partial likelihood. Simulation studies and an analysis of a semiparametric extension of a popular model for neural spike train data demonstrate the practical utility of the rate approach in comparison with the intensity approach. PMID:24550568

Quality choice in a health care market: a mixed duopoly approach.

PubMed

Sanjo, Yasuo

2009-05-01

We investigate a health care market with uncertainty in a mixed duopoly, where a partially privatized public hospital competes against a private hospital in terms of quality choice. We use a simple Hotelling-type spatial competition model by incorporating mean-variance analysis and the framework of partial privatization. We show how the variance in the quality perceived by patients affects the true quality of medical care provided by hospitals. In addition, we show that a case exists in which the quality of the partially privatized hospital becomes higher than that of the private hospital when the patient's preference for quality is relatively high.

Parallel Computation of Flow in Heterogeneous Media Modelled by Mixed Finite Elements

NASA Astrophysics Data System (ADS)

Cliffe, K. A.; Graham, I. G.; Scheichl, R.; Stals, L.

2000-11-01

In this paper we describe a fast parallel method for solving highly ill-conditioned saddle-point systems arising from mixed finite element simulations of stochastic partial differential equations (PDEs) modelling flow in heterogeneous media. Each realisation of these stochastic PDEs requires the solution of the linear first-order velocity-pressure system comprising Darcy's law coupled with an incompressibility constraint. The chief difficulty is that the permeability may be highly variable, especially when the statistical model has a large variance and a small correlation length. For reasonable accuracy, the discretisation has to be extremely fine. We solve these problems by first reducing the saddle-point formulation to a symmetric positive definite (SPD) problem using a suitable basis for the space of divergence-free velocities. The reduced problem is solved using parallel conjugate gradients preconditioned with an algebraically determined additive Schwarz domain decomposition preconditioner. The result is a solver which exhibits a good degree of robustness with respect to the mesh size as well as to the variance and to physically relevant values of the correlation length of the underlying permeability field. Numerical experiments exhibit almost optimal levels of parallel efficiency. The domain decomposition solver (DOUG, http://www.maths.bath.ac.uk/~parsoft) used here not only is applicable to this problem but can be used to solve general unstructured finite element systems on a wide range of parallel architectures.

Diffusion of surgical innovation among patients with kidney cancer

PubMed Central

Miller, David C.; Saigal, Christopher S.; Banerjee, Mousumi; Hanley, Jan; Litwin, Mark S.

2009-01-01

Background Despite their potential benefits to patients with kidney cancer, the adoption of partial nephrectomy and laparoscopy has been gradual and asymmetric. To clarify whether this trend reflects differences in kidney cancer patients or differences in surgeon practice styles, we compared the magnitude of surgeon-attributable variance in the use of partial nephrectomy and laparoscopic radical nephrectomy with that attributable to patient and tumor characteristics. Methods Using linked Surveillance, Epidemiology, and End Results-Medicare data, we identified a cohort of 5,483 Medicare beneficiaries treated surgically for kidney cancer between 1997 and 2002. We defined two primary outcomes: (1) use of partial nephrectomy, and (2) use of laparoscopy among patients undergoing radical nephrectomy. Using multilevel models, we estimated surgeon- and patient-level contributions to observed variations in the use of partial nephrectomy and laparoscopic radical nephrectomy. Results Of the 5,483 cases identified, 611(11.1%) underwent partial nephrectomy (43 performed laparoscopically), and 4,872 (88.9%) underwent radical nephrectomy (515 performed laparoscopically). After adjusting for patient demographics, comorbidity, tumor size and surgeon volume, the surgeon-attributable variance was 18.1% for partial nephrectomy and 37.4% for laparoscopy. For both outcomes, the percentage of total variance attributable to surgeon factors was consistently higher than that attributable to patient characteristics. Conclusions For many patients with kidney cancer, the surgery provided depends more on their surgeon’s practice style than on the characteristics of the patient and his or her disease. Consequently, dismantling barriers to surgeon adoption of partial nephrectomy and laparoscopy is an important step toward improving the quality of care for patients with early-stage kidney cancer. PMID:18330868

A model and variance reduction method for computing statistical outputs of stochastic elliptic partial differential equations

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

Vidal-Codina, F., E-mail: fvidal@mit.edu; Nguyen, N.C., E-mail: cuongng@mit.edu; Giles, M.B., E-mail: mike.giles@maths.ox.ac.uk

We present a model and variance reduction method for the fast and reliable computation of statistical outputs of stochastic elliptic partial differential equations. Our method consists of three main ingredients: (1) the hybridizable discontinuous Galerkin (HDG) discretization of elliptic partial differential equations (PDEs), which allows us to obtain high-order accurate solutions of the governing PDE; (2) the reduced basis method for a new HDG discretization of the underlying PDE to enable real-time solution of the parameterized PDE in the presence of stochastic parameters; and (3) a multilevel variance reduction method that exploits the statistical correlation among the different reduced basismore » approximations and the high-fidelity HDG discretization to accelerate the convergence of the Monte Carlo simulations. The multilevel variance reduction method provides efficient computation of the statistical outputs by shifting most of the computational burden from the high-fidelity HDG approximation to the reduced basis approximations. Furthermore, we develop a posteriori error estimates for our approximations of the statistical outputs. Based on these error estimates, we propose an algorithm for optimally choosing both the dimensions of the reduced basis approximations and the sizes of Monte Carlo samples to achieve a given error tolerance. We provide numerical examples to demonstrate the performance of the proposed method.« less

The Manifest Association Structure of the Single-Factor Model: Insights from Partial Correlations

ERIC Educational Resources Information Center

Salgueiro, Maria de Fatima; Smith, Peter W. F.; McDonald, John W.

2008-01-01

The association structure between manifest variables arising from the single-factor model is investigated using partial correlations. The additional insights to the practitioner provided by partial correlations for detecting a single-factor model are discussed. The parameter space for the partial correlations is presented, as are the patterns of…

Selecting band combinations with thematic mapper data

NASA Technical Reports Server (NTRS)

Sheffield, C. A.

1983-01-01

A problem arises in making color composite images because there are 210 different possible color presentations of TM three-band images. A method is given for reducing that 210 to a single choice, decided by the statistics of a scene or subscene, and taking into full account any correlations that exist between different bands. Instead of using total variance as the measure for information content of the band triplets, the ellipsoid of maximum volume is selected which discourages selection of bands with high correlation. The band triplet is obtained by computing and ranking in order the determinants of each 3 x 3 principal submatrix of the original matrix M. After selection of the best triplet, the assignment of colors is made by using the actual variances (the diagonal elements of M): green (maximum variance), red (second largest variance), blue (smallest variance).

A homotopy analysis method for the nonlinear partial differential equations arising in engineering

NASA Astrophysics Data System (ADS)

Hariharan, G.

2017-05-01

In this article, we have established the homotopy analysis method (HAM) for solving a few partial differential equations arising in engineering. This technique provides the solutions in rapid convergence series with computable terms for the problems with high degree of nonlinear terms appearing in the governing differential equations. The convergence analysis of the proposed method is also discussed. Finally, we have given some illustrative examples to demonstrate the validity and applicability of the proposed method.

Eta Squared and Partial Eta Squared as Measures of Effect Size in Educational Research

ERIC Educational Resources Information Center

Richardson, John T. E.

2011-01-01

Eta squared measures the proportion of the total variance in a dependent variable that is associated with the membership of different groups defined by an independent variable. Partial eta squared is a similar measure in which the effects of other independent variables and interactions are partialled out. The development of these measures is…

The Artificial Hamiltonian, First Integrals, and Closed-Form Solutions of Dynamical Systems for Epidemics

NASA Astrophysics Data System (ADS)

Naz, Rehana; Naeem, Imran

2018-03-01

The non-standard Hamiltonian system, also referred to as a partial Hamiltonian system in the literature, of the form {\\dot q^i} = {partial H}/{partial {p_i}},\\dot p^i = - {partial H}/{partial {q_i}} + {Γ ^i}(t,{q^i},{p_i}) appears widely in economics, physics, mechanics, and other fields. The non-standard (partial) Hamiltonian systems arise from physical Hamiltonian structures as well as from artificial Hamiltonian structures. We introduce the term `artificial Hamiltonian' for the Hamiltonian of a model having no physical structure. We provide here explicitly the notion of an artificial Hamiltonian for dynamical systems of ordinary differential equations (ODEs). Also, we show that every system of second-order ODEs can be expressed as a non-standard (partial) Hamiltonian system of first-order ODEs by introducing an artificial Hamiltonian. This notion of an artificial Hamiltonian gives a new way to solve dynamical systems of first-order ODEs and systems of second-order ODEs that can be expressed as a non-standard (partial) Hamiltonian system by using the known techniques applicable to the non-standard Hamiltonian systems. We employ the proposed notion to solve dynamical systems of first-order ODEs arising in epidemics.

The use of analysis of variance procedures in biological studies

USGS Publications Warehouse

Williams, B.K.

1987-01-01

The analysis of variance (ANOVA) is widely used in biological studies, yet there remains considerable confusion among researchers about the interpretation of hypotheses being tested. Ambiguities arise when statistical designs are unbalanced, and in particular when not all combinations of design factors are represented in the data. This paper clarifies the relationship among hypothesis testing, statistical modelling and computing procedures in ANOVA for unbalanced data. A simple two-factor fixed effects design is used to illustrate three common parametrizations for ANOVA models, and some associations among these parametrizations are developed. Biologically meaningful hypotheses for main effects and interactions are given in terms of each parametrization, and procedures for testing the hypotheses are described. The standard statistical computing procedures in ANOVA are given along with their corresponding hypotheses. Throughout the development unbalanced designs are assumed and attention is given to problems that arise with missing cells.

Explaining the sex difference in dyslexia.

PubMed

Arnett, Anne B; Pennington, Bruce F; Peterson, Robin L; Willcutt, Erik G; DeFries, John C; Olson, Richard K

2017-06-01

Males are diagnosed with dyslexia more frequently than females, even in epidemiological samples. This may be explained by greater variance in males' reading performance. We expand on previous research by rigorously testing the variance difference theory, and testing for mediation of the sex difference by cognitive correlates. We developed an analytic framework that can be applied to group differences in any psychiatric disorder. Males' overrepresentation in the low performance tail of the reading distribution was accounted for by mean and variance differences across sex. There was no sex difference at the high performance tail. Processing speed (PS) and inhibitory control partially mediated the sex difference. Verbal reasoning emerged as a strength in males. Our results complement a previous finding that PS partially mediates the sex difference in symptoms of attention deficit/hyperactivity disorder (ADHD), and helps explain the sex difference in both dyslexia and ADHD and their comorbidity. © 2017 Association for Child and Adolescent Mental Health.

Additive Partial Least Squares for efficient modelling of independent variance sources demonstrated on practical case studies.

PubMed

Luoma, Pekka; Natschläger, Thomas; Malli, Birgit; Pawliczek, Marcin; Brandstetter, Markus

2018-05-12

A model recalibration method based on additive Partial Least Squares (PLS) regression is generalized for multi-adjustment scenarios of independent variance sources (referred to as additive PLS - aPLS). aPLS allows for effortless model readjustment under changing measurement conditions and the combination of independent variance sources with the initial model by means of additive modelling. We demonstrate these distinguishing features on two NIR spectroscopic case-studies. In case study 1 aPLS was used as a readjustment method for an emerging offset. The achieved RMS error of prediction (1.91 a.u.) was of similar level as before the offset occurred (2.11 a.u.). In case-study 2 a calibration combining different variance sources was conducted. The achieved performance was of sufficient level with an absolute error being better than 0.8% of the mean concentration, therefore being able to compensate negative effects of two independent variance sources. The presented results show the applicability of the aPLS approach. The main advantages of the method are that the original model stays unadjusted and that the modelling is conducted on concrete changes in the spectra thus supporting efficient (in most cases straightforward) modelling. Additionally, the method is put into context of existing machine learning algorithms. Copyright © 2018 Elsevier B.V. All rights reserved.

Eye-hand coordination during a double-step task: evidence for a common stochastic accumulator

PubMed Central

Gopal, Atul

2015-01-01

Many studies of reaching and pointing have shown significant spatial and temporal correlations between eye and hand movements. Nevertheless, it remains unclear whether these correlations are incidental, arising from common inputs (independent model); whether these correlations represent an interaction between otherwise independent eye and hand systems (interactive model); or whether these correlations arise from a single dedicated eye-hand system (common command model). Subjects were instructed to redirect gaze and pointing movements in a double-step task in an attempt to decouple eye-hand movements and causally distinguish between the three architectures. We used a drift-diffusion framework in the context of a race model, which has been previously used to explain redirect behavior for eye and hand movements separately, to predict the pattern of eye-hand decoupling. We found that the common command architecture could best explain the observed frequency of different eye and hand response patterns to the target step. A common stochastic accumulator for eye-hand coordination also predicts comparable variances, despite significant difference in the means of the eye and hand reaction time (RT) distributions, which we tested. Consistent with this prediction, we observed that the variances of the eye and hand RTs were similar, despite much larger hand RTs (∼90 ms). Moreover, changes in mean eye RTs, which also increased eye RT variance, produced a similar increase in mean and variance of the associated hand RT. Taken together, these data suggest that a dedicated circuit underlies coordinated eye-hand planning. PMID:26084906

Modeling the subfilter scalar variance for large eddy simulation in forced isotropic turbulence

NASA Astrophysics Data System (ADS)

Cheminet, Adam; Blanquart, Guillaume

2011-11-01

Static and dynamic model for the subfilter scalar variance in homogeneous isotropic turbulence are investigated using direct numerical simulations (DNS) of a lineary forced passive scalar field. First, we introduce a new scalar forcing technique conditioned only on the scalar field which allows the fluctuating scalar field to reach a statistically stationary state. Statistical properties, including 2nd and 3rd statistical moments, spectra, and probability density functions of the scalar field have been analyzed. Using this technique, we performed constant density and variable density DNS of scalar mixing in isotropic turbulence. The results are used in an a-priori study of scalar variance models. Emphasis is placed on further studying the dynamic model introduced by G. Balarac, H. Pitsch and V. Raman [Phys. Fluids 20, (2008)]. Scalar variance models based on Bedford and Yeo's expansion are accurate for small filter width but errors arise in the inertial subrange. Results suggest that a constant coefficient computed from an assumed Kolmogorov spectrum is often sufficient to predict the subfilter scalar variance.

Hemangiopericytoma arising from the wall of the urinary bladder.

PubMed

Kibar, Y; Uzar, A I; Erdemir, F; Ozcan, A; Coban, H; Seckin, B

2006-01-01

Hemangiopericytoma (HPC) arising from within the urinary bladder is exceptionally rare. A 45-year-old man having the symptoms of left groin pain, vague suprapubic discomfort and frequency was admitted to our clinic. Pelvic tomography revealed a tumor in the bladder wall measuring 4 x 3 cm and was not clearly distinct from the lower abdominal wall. Partial cystectomy was performed and the histopathological examination confirmed the hemangiopericytoma. Three thousand rad exterior beam irradiation was performed after operation. Partial cystectomy and adjuvant radiotherapy may be a simple and effective alternative operation for the patient with HPC.

Linkage disequilibrium and association mapping.

PubMed

Weir, B S

2008-01-01

Linkage disequilibrium refers to the association between alleles at different loci. The standard definition applies to two alleles in the same gamete, and it can be regarded as the covariance of indicator variables for the states of those two alleles. The corresponding correlation coefficient rho is the parameter that arises naturally in discussions of tests of association between markers and genetic diseases. A general treatment of association tests makes use of the additive and nonadditive components of variance for the disease gene. In almost all expressions that describe the behavior of association tests, additive variance components are modified by the squared correlation coefficient rho2 and the nonadditive variance components by rho4, suggesting that nonadditive components have less influence than additive components on association tests.

Partial Variance of Increments Method in Solar Wind Observations and Plasma Simulations

NASA Astrophysics Data System (ADS)

Greco, A.; Matthaeus, W. H.; Perri, S.; Osman, K. T.; Servidio, S.; Wan, M.; Dmitruk, P.

2018-02-01

The method called "PVI" (Partial Variance of Increments) has been increasingly used in analysis of spacecraft and numerical simulation data since its inception in 2008. The purpose of the method is to study the kinematics and formation of coherent structures in space plasmas, a topic that has gained considerable attention, leading the development of identification methods, observations, and associated theoretical research based on numerical simulations. This review paper will summarize key features of the method and provide a synopsis of the main results obtained by various groups using the method. This will enable new users or those considering methods of this type to find details and background collected in one place.

Psychosocial work characteristics predicting daytime sleepiness in day and shift workers.

PubMed

Takahashi, Masaya; Nakata, Akinori; Haratani, Takashi; Otsuka, Yasumasa; Kaida, Kosuke; Fukasawa, Kenji

2006-01-01

Characteristics of work organization other than working time arrangements may contribute importantly to daytime sleepiness. The present study was designed to identify the psychosocial factors at work that predict daytime sleepiness in a sample of day and shift workers. Participants working at a pulp and chemical factory completed an annual questionnaire regarding psychosocial factors at work using the U.S. National Institute for Occupational Safety and Health Generic Job Stress Questionnaire (i.e., quantitative workload, variance in workload, job control, support from supervisor, coworkers, or family/friends, job satisfaction, and depressive symptoms), as well as daytime sleepiness (through the Epworth Sleepiness Scale [ESS]) and sleep disturbances for three years starting in 2002 (response rates, 94.6-99.0%). The present analysis included 55 day workers (11 women) and 57 shift workers (all men) who participated in all three years of the study, worked under the same work schedule throughout the study period, and had no missing data on any of the daytime sleep items. A repeated-measures analysis of covariance (ANCOVA) was used to test the effects of work schedule (day vs. shift work) and psychosocial factors at work in 2002 on the ESS scores in subsequent years, with sleep duration, insomnia symptoms, chronic diseases, and sleepiness levels at baseline as covariates. Given significant and near-significant interactions of work schedules with psychosocial factor or study year, the ANCOVA, with the factors of psychosocial work characteristics and study year, was performed by type of work schedule. The results indicated a significant main effect of psychosocial work characteristics (p = 0.010, partial eng2 = 0.14) and an almost significant main effect of study year (p = 0.067, partial eng2 = 0.06) and interaction between psychosocial work characteristics and study year (p = 0.085, partial eng2 = 0.06) for variance in workload among the day work group. The day workers reporting high variance in workload in 2002 exhibited significantly higher ESS scores in 2003 and 2004 than did those reporting low variance in workload. The ANCOVA for the shift work group showed a main effect of psychosocial work characteristics for job satisfaction (p = 0.026, partial eng2 = 0.10) and depressive symptoms (p = 0.094, partial eng2 = 0.06) with the interaction between psychosocial work characteristics and study year for job satisfaction (p = 0.172, partial eng2 = 0.04) and depressive symptoms (p = 0.035, partial eng2 = 0.07). The shift workers with low job satisfaction and high symptoms of depression in 2002 showed significantly greater ESS scores in 2003 and/or 2004 than did those with opposite characteristics. These results may suggest a potential predictive value of variance in workload for day workers as well as job satisfaction and depressive symptoms for shift workers with respect to daytime sleepiness. The present findings may imply that redesigning these aspects of work environment would be of help in managing daytime sleepiness.

Antagonistic versus non-antagonistic models of balancing selection: Characterizing the relative timescales and hitchhiking effects of partial selective sweeps

PubMed Central

Connallon, Tim; Clark, Andrew G.

2012-01-01

Antagonistically selected alleles -- those with opposing fitness effects between sexes, environments, or fitness components -- represent an important component of additive genetic variance in fitness-related traits, with stably balanced polymorphisms often hypothesized to contribute to observed quantitative genetic variation. Balancing selection hypotheses imply that intermediate-frequency alleles disproportionately contribute to genetic variance of life history traits and fitness. Such alleles may also associate with population genetic footprints of recent selection, including reduced genetic diversity and inflated linkage disequilibrium at linked, neutral sites. Here, we compare the evolutionary dynamics of different balancing selection models, and characterize the evolutionary timescale and hitchhiking effects of partial selective sweeps generated under antagonistic versus non-antagonistic (e.g., overdominant and frequency-dependent selection) processes. We show that that the evolutionary timescales of partial sweeps tend to be much longer, and hitchhiking effects are drastically weaker, under scenarios of antagonistic selection. These results predict an interesting mismatch between molecular population genetic and quantitative genetic patterns of variation. Balanced, antagonistically selected alleles are expected to contribute more to additive genetic variance for fitness than alleles maintained by classic, non-antagonistic mechanisms. Nevertheless, classical mechanisms of balancing selection are much more likely to generate strong population genetic signatures of recent balancing selection. PMID:23461340

Measures of Working Memory Span and Verbal Rehearsal Speed in Deaf Children after Cochlear Implantation

PubMed Central

Pisoni, David B.; Cleary, Miranda

2012-01-01

Large individual differences in spoken word recognition performance have been found in deaf children after cochlear implantation. Recently, Pisoni and Geers (2000) reported that simple forward digit span measures of verbal working memory were significantly correlated with spoken word recognition scores even after potentially confounding variables were statistically controlled for. The present study replicates and extends these initial findings to the full set of 176 participants in the CID cochlear implant study. The pooled data indicate that despite statistical “partialling-out” of differences in chronological age, communication mode, duration of deafness, duration of device use, age at onset of deafness, number of active electrodes, and speech feature discrimination, significant correlations still remain between digit span and several measures of spoken word recognition. Strong correlations were also observed between speaking rate and both forward and backward digit span, a result that is similar to previously reported findings in normalhearing adults and children. The results suggest that perhaps as much as 20% of the currently unexplained variance in spoken word recognition scores may be independently accounted for by individual differences in cognitive factors related to the speed and efficiency with which phonological and lexical representations of spoken words are maintained in and retrieved from working memory. A smaller percentage, perhaps about 7% of the currently unexplained variance in spoken word recognition scores, may be accounted for in terms of working memory capacity. We discuss how these relationships may arise and their contribution to subsequent speech and language development in prelingually deaf children who use cochlear implants. PMID:12612485

Eta Squared, Partial Eta Squared, and Misreporting of Effect Size in Communication Research.

ERIC Educational Resources Information Center

Levine, Timothy R.; Hullett, Craig R.

2002-01-01

Alerts communication researchers to potential errors stemming from the use of SPSS (Statistical Package for the Social Sciences) to obtain estimates of eta squared in analysis of variance (ANOVA). Strives to clarify issues concerning the development and appropriate use of eta squared and partial eta squared in ANOVA. Discusses the reporting of…

Using partial least squares regression as a predictive tool in describing equine third metacarpal bone shape.

PubMed

Liley, Helen; Zhang, Ju; Firth, Elwyn; Fernandez, Justin; Besier, Thor

2017-11-01

Population variance in bone shape is an important consideration when applying the results of subject-specific computational models to a population. In this letter, we demonstrate the ability of partial least squares regression to provide an improved shape prediction of the equine third metacarpal epiphysis, using two easily obtained measurements.

Removing an intersubject variance component in a general linear model improves multiway factoring of event-related spectral perturbations in group EEG studies.

PubMed

Spence, Jeffrey S; Brier, Matthew R; Hart, John; Ferree, Thomas C

2013-03-01

Linear statistical models are used very effectively to assess task-related differences in EEG power spectral analyses. Mixed models, in particular, accommodate more than one variance component in a multisubject study, where many trials of each condition of interest are measured on each subject. Generally, intra- and intersubject variances are both important to determine correct standard errors for inference on functions of model parameters, but it is often assumed that intersubject variance is the most important consideration in a group study. In this article, we show that, under common assumptions, estimates of some functions of model parameters, including estimates of task-related differences, are properly tested relative to the intrasubject variance component only. A substantial gain in statistical power can arise from the proper separation of variance components when there is more than one source of variability. We first develop this result analytically, then show how it benefits a multiway factoring of spectral, spatial, and temporal components from EEG data acquired in a group of healthy subjects performing a well-studied response inhibition task. Copyright © 2011 Wiley Periodicals, Inc.

Constraints on the Observation of Partial Match Costs: Implications for Transfer-Appropriate Processing Approaches to Immediate Priming

ERIC Educational Resources Information Center

Leboe, Jason P.; Leboe, Launa C.; Milliken, Bruce

2010-01-01

According to a transfer-appropriate processing framework, immediate priming costs arise from a match between a prime and probe event on 1 dimension and a difference between those 2 events on some other dimension (i.e., a partial match). In Experiment 1, the authors used a Stroop priming procedure to generate 6 variants of partial match, yet only 1…

ROBUST ESTIMATION OF MEAN AND VARIANCE USING ENVIRONMENTAL DATA SETS WITH BELOW DETECTION LIMIT OBSERVATIONS

EPA Science Inventory

Scientists, especially environmental scientists often encounter trace level concentrations that are typically reported as less than a certain limit of detection, L. Type 1, left-censored data arise when certain low values lying below L are ignored or unknown as they cannot be mea...

Eta- and Partial Eta-Squared in L2 Research: A Cautionary Review and Guide to More Appropriate Usage

ERIC Educational Resources Information Center

Norouzian, Reza; Plonsky, Luke

2018-01-01

Eta-squared (?[superscript 2]) and partial eta-squared (?[subscript p][superscript 2]) are effect sizes that express the amount of variance accounted for by one or more independent variables. These indices are generally used in conjunction with ANOVA, the most commonly used statistical test in second language (L2) research (Plonsky, 2013).…

Genetic Variance in Homophobia: Evidence from Self- and Peer Reports.

PubMed

Zapko-Willmes, Alexandra; Kandler, Christian

2018-01-01

The present twin study combined self- and peer assessments of twins' general homophobia targeting gay men in order to replicate previous behavior genetic findings across different rater perspectives and to disentangle self-rater-specific variance from common variance in self- and peer-reported homophobia (i.e., rater-consistent variance). We hypothesized rater-consistent variance in homophobia to be attributable to genetic and nonshared environmental effects, and self-rater-specific variance to be partially accounted for by genetic influences. A sample of 869 twins and 1329 peer raters completed a seven item scale containing cognitive, affective, and discriminatory homophobic tendencies. After correction for age and sex differences, we found most of the genetic contributions (62%) and significant nonshared environmental contributions (16%) to individual differences in self-reports on homophobia to be also reflected in peer-reported homophobia. A significant genetic component, however, was self-report-specific (38%), suggesting that self-assessments alone produce inflated heritability estimates to some degree. Different explanations are discussed.

Network Structure and Biased Variance Estimation in Respondent Driven Sampling

PubMed Central

Verdery, Ashton M.; Mouw, Ted; Bauldry, Shawn; Mucha, Peter J.

2015-01-01

This paper explores bias in the estimation of sampling variance in Respondent Driven Sampling (RDS). Prior methodological work on RDS has focused on its problematic assumptions and the biases and inefficiencies of its estimators of the population mean. Nonetheless, researchers have given only slight attention to the topic of estimating sampling variance in RDS, despite the importance of variance estimation for the construction of confidence intervals and hypothesis tests. In this paper, we show that the estimators of RDS sampling variance rely on a critical assumption that the network is First Order Markov (FOM) with respect to the dependent variable of interest. We demonstrate, through intuitive examples, mathematical generalizations, and computational experiments that current RDS variance estimators will always underestimate the population sampling variance of RDS in empirical networks that do not conform to the FOM assumption. Analysis of 215 observed university and school networks from Facebook and Add Health indicates that the FOM assumption is violated in every empirical network we analyze, and that these violations lead to substantially biased RDS estimators of sampling variance. We propose and test two alternative variance estimators that show some promise for reducing biases, but which also illustrate the limits of estimating sampling variance with only partial information on the underlying population social network. PMID:26679927

Construction and accuracy of partial differential equation approximations to the chemical master equation.

PubMed

Grima, Ramon

2011-11-01

The mesoscopic description of chemical kinetics, the chemical master equation, can be exactly solved in only a few simple cases. The analytical intractability stems from the discrete character of the equation, and hence considerable effort has been invested in the development of Fokker-Planck equations, second-order partial differential equation approximations to the master equation. We here consider two different types of higher-order partial differential approximations, one derived from the system-size expansion and the other from the Kramers-Moyal expansion, and derive the accuracy of their predictions for chemical reactive networks composed of arbitrary numbers of unimolecular and bimolecular reactions. In particular, we show that the partial differential equation approximation of order Q from the Kramers-Moyal expansion leads to estimates of the mean number of molecules accurate to order Ω(-(2Q-3)/2), of the variance of the fluctuations in the number of molecules accurate to order Ω(-(2Q-5)/2), and of skewness accurate to order Ω(-(Q-2)). We also show that for large Q, the accuracy in the estimates can be matched only by a partial differential equation approximation from the system-size expansion of approximate order 2Q. Hence, we conclude that partial differential approximations based on the Kramers-Moyal expansion generally lead to considerably more accurate estimates in the mean, variance, and skewness than approximations of the same order derived from the system-size expansion.

On a numerical method for solving integro-differential equations with variable coefficients with applications in finance

NASA Astrophysics Data System (ADS)

Kudryavtsev, O.; Rodochenko, V.

2018-03-01

We propose a new general numerical method aimed to solve integro-differential equations with variable coefficients. The problem under consideration arises in finance where in the context of pricing barrier options in a wide class of stochastic volatility models with jumps. To handle the effect of the correlation between the price and the variance, we use a suitable substitution for processes. Then we construct a Markov-chain approximation for the variation process on small time intervals and apply a maturity randomization technique. The result is a system of boundary problems for integro-differential equations with constant coefficients on the line in each vertex of the chain. We solve the arising problems using a numerical Wiener-Hopf factorization method. The approximate formulae for the factors are efficiently implemented by means of the Fast Fourier Transform. Finally, we use a recurrent procedure that moves backwards in time on the variance tree. We demonstrate the convergence of the method using Monte-Carlo simulations and compare our results with the results obtained by the Wiener-Hopf method with closed-form expressions of the factors.

Analysis of a genetically structured variance heterogeneity model using the Box-Cox transformation.

PubMed

Yang, Ye; Christensen, Ole F; Sorensen, Daniel

2011-02-01

Over recent years, statistical support for the presence of genetic factors operating at the level of the environmental variance has come from fitting a genetically structured heterogeneous variance model to field or experimental data in various species. Misleading results may arise due to skewness of the marginal distribution of the data. To investigate how the scale of measurement affects inferences, the genetically structured heterogeneous variance model is extended to accommodate the family of Box-Cox transformations. Litter size data in rabbits and pigs that had previously been analysed in the untransformed scale were reanalysed in a scale equal to the mode of the marginal posterior distribution of the Box-Cox parameter. In the rabbit data, the statistical evidence for a genetic component at the level of the environmental variance is considerably weaker than that resulting from an analysis in the original metric. In the pig data, the statistical evidence is stronger, but the coefficient of correlation between additive genetic effects affecting mean and variance changes sign, compared to the results in the untransformed scale. The study confirms that inferences on variances can be strongly affected by the presence of asymmetry in the distribution of data. We recommend that to avoid one important source of spurious inferences, future work seeking support for a genetic component acting on environmental variation using a parametric approach based on normality assumptions confirms that these are met.

An Evolutionary Perspective on Epistasis and the Missing Heritability

PubMed Central

Hemani, Gibran; Knott, Sara; Haley, Chris

2013-01-01

The relative importance between additive and non-additive genetic variance has been widely argued in quantitative genetics. By approaching this question from an evolutionary perspective we show that, while additive variance can be maintained under selection at a low level for some patterns of epistasis, the majority of the genetic variance that will persist is actually non-additive. We propose that one reason that the problem of the “missing heritability” arises is because the additive genetic variation that is estimated to be contributing to the variance of a trait will most likely be an artefact of the non-additive variance that can be maintained over evolutionary time. In addition, it can be shown that even a small reduction in linkage disequilibrium between causal variants and observed SNPs rapidly erodes estimates of epistatic variance, leading to an inflation in the perceived importance of additive effects. We demonstrate that the perception of independent additive effects comprising the majority of the genetic architecture of complex traits is biased upwards and that the search for causal variants in complex traits under selection is potentially underpowered by parameterising for additive effects alone. Given dense SNP panels the detection of causal variants through genome-wide association studies may be improved by searching for epistatic effects explicitly. PMID:23509438

A close examination of double filtering with fold change and t test in microarray analysis

PubMed Central

2009-01-01

Background Many researchers use the double filtering procedure with fold change and t test to identify differentially expressed genes, in the hope that the double filtering will provide extra confidence in the results. Due to its simplicity, the double filtering procedure has been popular with applied researchers despite the development of more sophisticated methods. Results This paper, for the first time to our knowledge, provides theoretical insight on the drawback of the double filtering procedure. We show that fold change assumes all genes to have a common variance while t statistic assumes gene-specific variances. The two statistics are based on contradicting assumptions. Under the assumption that gene variances arise from a mixture of a common variance and gene-specific variances, we develop the theoretically most powerful likelihood ratio test statistic. We further demonstrate that the posterior inference based on a Bayesian mixture model and the widely used significance analysis of microarrays (SAM) statistic are better approximations to the likelihood ratio test than the double filtering procedure. Conclusion We demonstrate through hypothesis testing theory, simulation studies and real data examples, that well constructed shrinkage testing methods, which can be united under the mixture gene variance assumption, can considerably outperform the double filtering procedure. PMID:19995439

Biomechanical considerations on tooth-implant supported fixed partial dentures

PubMed Central

Calvani, Pasquale; Hirayama, Hiroshi

2012-01-01

This article discusses the connection of teeth to implants, in order to restore partial edentulism. The main problem arising from this connection is tooth intrusion, which can occur in up to 7.3% of the cases. The justification of this complication is being attempted through the perspective of biomechanics of the involved anatomical structures, that is, the periodontal ligament and the bone, as well as that of the teeth- and implant-supported fixed partial dentures. PMID:23255882

Verbal Working Memory in Children With Cochlear Implants

PubMed Central

Caldwell-Tarr, Amanda; Low, Keri E.; Lowenstein, Joanna H.

2017-01-01

Purpose Verbal working memory in children with cochlear implants and children with normal hearing was examined. Participants Ninety-three fourth graders (47 with normal hearing, 46 with cochlear implants) participated, all of whom were in a longitudinal study and had working memory assessed 2 years earlier. Method A dual-component model of working memory was adopted, and a serial recall task measured storage and processing. Potential predictor variables were phonological awareness, vocabulary knowledge, nonverbal IQ, and several treatment variables. Potential dependent functions were literacy, expressive language, and speech-in-noise recognition. Results Children with cochlear implants showed deficits in storage and processing, similar in size to those at second grade. Predictors of verbal working memory differed across groups: Phonological awareness explained the most variance in children with normal hearing; vocabulary explained the most variance in children with cochlear implants. Treatment variables explained little of the variance. Where potentially dependent functions were concerned, verbal working memory accounted for little variance once the variance explained by other predictors was removed. Conclusions The verbal working memory deficits of children with cochlear implants arise due to signal degradation, which limits their abilities to acquire phonological awareness. That hinders their abilities to store items using a phonological code. PMID:29075747

Easy and accurate variance estimation of the nonparametric estimator of the partial area under the ROC curve and its application.

PubMed

Yu, Jihnhee; Yang, Luge; Vexler, Albert; Hutson, Alan D

2016-06-15

The receiver operating characteristic (ROC) curve is a popular technique with applications, for example, investigating an accuracy of a biomarker to delineate between disease and non-disease groups. A common measure of accuracy of a given diagnostic marker is the area under the ROC curve (AUC). In contrast with the AUC, the partial area under the ROC curve (pAUC) looks into the area with certain specificities (i.e., true negative rate) only, and it can be often clinically more relevant than examining the entire ROC curve. The pAUC is commonly estimated based on a U-statistic with the plug-in sample quantile, making the estimator a non-traditional U-statistic. In this article, we propose an accurate and easy method to obtain the variance of the nonparametric pAUC estimator. The proposed method is easy to implement for both one biomarker test and the comparison of two correlated biomarkers because it simply adapts the existing variance estimator of U-statistics. In this article, we show accuracy and other advantages of the proposed variance estimation method by broadly comparing it with previously existing methods. Further, we develop an empirical likelihood inference method based on the proposed variance estimator through a simple implementation. In an application, we demonstrate that, depending on the inferences by either the AUC or pAUC, we can make a different decision on a prognostic ability of a same set of biomarkers. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Collinearity and Causal Diagrams: A Lesson on the Importance of Model Specification.

PubMed

Schisterman, Enrique F; Perkins, Neil J; Mumford, Sunni L; Ahrens, Katherine A; Mitchell, Emily M

2017-01-01

Correlated data are ubiquitous in epidemiologic research, particularly in nutritional and environmental epidemiology where mixtures of factors are often studied. Our objectives are to demonstrate how highly correlated data arise in epidemiologic research and provide guidance, using a directed acyclic graph approach, on how to proceed analytically when faced with highly correlated data. We identified three fundamental structural scenarios in which high correlation between a given variable and the exposure can arise: intermediates, confounders, and colliders. For each of these scenarios, we evaluated the consequences of increasing correlation between the given variable and the exposure on the bias and variance for the total effect of the exposure on the outcome using unadjusted and adjusted models. We derived closed-form solutions for continuous outcomes using linear regression and empirically present our findings for binary outcomes using logistic regression. For models properly specified, total effect estimates remained unbiased even when there was almost perfect correlation between the exposure and a given intermediate, confounder, or collider. In general, as the correlation increased, the variance of the parameter estimate for the exposure in the adjusted models increased, while in the unadjusted models, the variance increased to a lesser extent or decreased. Our findings highlight the importance of considering the causal framework under study when specifying regression models. Strategies that do not take into consideration the causal structure may lead to biased effect estimation for the original question of interest, even under high correlation.

High-Dimensional Heteroscedastic Regression with an Application to eQTL Data Analysis

PubMed Central

Daye, Z. John; Chen, Jinbo; Li, Hongzhe

2011-01-01

Summary We consider the problem of high-dimensional regression under non-constant error variances. Despite being a common phenomenon in biological applications, heteroscedasticity has, so far, been largely ignored in high-dimensional analysis of genomic data sets. We propose a new methodology that allows non-constant error variances for high-dimensional estimation and model selection. Our method incorporates heteroscedasticity by simultaneously modeling both the mean and variance components via a novel doubly regularized approach. Extensive Monte Carlo simulations indicate that our proposed procedure can result in better estimation and variable selection than existing methods when heteroscedasticity arises from the presence of predictors explaining error variances and outliers. Further, we demonstrate the presence of heteroscedasticity in and apply our method to an expression quantitative trait loci (eQTLs) study of 112 yeast segregants. The new procedure can automatically account for heteroscedasticity in identifying the eQTLs that are associated with gene expression variations and lead to smaller prediction errors. These results demonstrate the importance of considering heteroscedasticity in eQTL data analysis. PMID:22547833

On the validity of within-nuclear-family genetic association analysis in samples of extended families.

PubMed

Bureau, Alexandre; Duchesne, Thierry

2015-12-01

Splitting extended families into their component nuclear families to apply a genetic association method designed for nuclear families is a widespread practice in familial genetic studies. Dependence among genotypes and phenotypes of nuclear families from the same extended family arises because of genetic linkage of the tested marker with a risk variant or because of familial specificity of genetic effects due to gene-environment interaction. This raises concerns about the validity of inference conducted under the assumption of independence of the nuclear families. We indeed prove theoretically that, in a conditional logistic regression analysis applicable to disease cases and their genotyped parents, the naive model-based estimator of the variance of the coefficient estimates underestimates the true variance. However, simulations with realistic effect sizes of risk variants and variation of this effect from family to family reveal that the underestimation is negligible. The simulations also show the greater efficiency of the model-based variance estimator compared to a robust empirical estimator. Our recommendation is therefore, to use the model-based estimator of variance for inference on effects of genetic variants.

Limited variance control in statistical low thrust guidance analysis. [stochastic algorithm for SEP comet Encke flyby mission

NASA Technical Reports Server (NTRS)

Jacobson, R. A.

1975-01-01

Difficulties arise in guiding a solar electric propulsion spacecraft due to nongravitational accelerations caused by random fluctuations in the magnitude and direction of the thrust vector. These difficulties may be handled by using a low thrust guidance law based on the linear-quadratic-Gaussian problem of stochastic control theory with a minimum terminal miss performance criterion. Explicit constraints are imposed on the variances of the control parameters, and an algorithm based on the Hilbert space extension of a parameter optimization method is presented for calculation of gains in the guidance law. The terminal navigation of a 1980 flyby mission to the comet Encke is used as an example.

The effect of model uncertainty on some optimal routing problems

NASA Technical Reports Server (NTRS)

Mohanty, Bibhu; Cassandras, Christos G.

1991-01-01

The effect of model uncertainties on optimal routing in a system of parallel queues is examined. The uncertainty arises in modeling the service time distribution for the customers (jobs, packets) to be served. For a Poisson arrival process and Bernoulli routing, the optimal mean system delay generally depends on the variance of this distribution. However, as the input traffic load approaches the system capacity the optimal routing assignment and corresponding mean system delay are shown to converge to a variance-invariant point. The implications of these results are examined in the context of gradient-based routing algorithms. An example of a model-independent algorithm using online gradient estimation is also included.

Influence function based variance estimation and missing data issues in case-cohort studies.

PubMed

Mark, S D; Katki, H

2001-12-01

Recognizing that the efficiency in relative risk estimation for the Cox proportional hazards model is largely constrained by the total number of cases, Prentice (1986) proposed the case-cohort design in which covariates are measured on all cases and on a random sample of the cohort. Subsequent to Prentice, other methods of estimation and sampling have been proposed for these designs. We formalize an approach to variance estimation suggested by Barlow (1994), and derive a robust variance estimator based on the influence function. We consider the applicability of the variance estimator to all the proposed case-cohort estimators, and derive the influence function when known sampling probabilities in the estimators are replaced by observed sampling fractions. We discuss the modifications required when cases are missing covariate information. The missingness may occur by chance, and be completely at random; or may occur as part of the sampling design, and depend upon other observed covariates. We provide an adaptation of S-plus code that allows estimating influence function variances in the presence of such missing covariates. Using examples from our current case-cohort studies on esophageal and gastric cancer, we illustrate how our results our useful in solving design and analytic issues that arise in practice.

Size-distribution analysis of macromolecules by sedimentation velocity ultracentrifugation and lamm equation modeling.

PubMed

Schuck, P

2000-03-01

A new method for the size-distribution analysis of polymers by sedimentation velocity analytical ultracentrifugation is described. It exploits the ability of Lamm equation modeling to discriminate between the spreading of the sedimentation boundary arising from sample heterogeneity and from diffusion. Finite element solutions of the Lamm equation for a large number of discrete noninteracting species are combined with maximum entropy regularization to represent a continuous size-distribution. As in the program CONTIN, the parameter governing the regularization constraint is adjusted by variance analysis to a predefined confidence level. Estimates of the partial specific volume and the frictional ratio of the macromolecules are used to calculate the diffusion coefficients, resulting in relatively high-resolution sedimentation coefficient distributions c(s) or molar mass distributions c(M). It can be applied to interference optical data that exhibit systematic noise components, and it does not require solution or solvent plateaus to be established. More details on the size-distribution can be obtained than from van Holde-Weischet analysis. The sensitivity to the values of the regularization parameter and to the shape parameters is explored with the help of simulated sedimentation data of discrete and continuous model size distributions, and by applications to experimental data of continuous and discrete protein mixtures.

Mapping target signatures via partial unmixing of AVIRIS data

NASA Technical Reports Server (NTRS)

Boardman, Joseph W.; Kruse, Fred A.; Green, Robert O.

1995-01-01

A complete spectral unmixing of a complicated AVIRIS scene may not always be possible or even desired. High quality data of spectrally complex areas are very high dimensional and are consequently difficult to fully unravel. Partial unmixing provides a method of solving only that fraction of the data inversion problem that directly relates to the specific goals of the investigation. Many applications of imaging spectrometry can be cast in the form of the following question: 'Are my target signatures present in the scene, and if so, how much of each target material is present in each pixel?' This is a partial unmixing problem. The number of unmixing endmembers is one greater than the number of spectrally defined target materials. The one additional endmember can be thought of as the composite of all the other scene materials, or 'everything else'. Several workers have proposed partial unmixing schemes for imaging spectrometry data, but each has significant limitations for operational application. The low probability detection methods described by Farrand and Harsanyi and the foreground-background method of Smith et al are both examples of such partial unmixing strategies. The new method presented here builds on these innovative analysis concepts, combining their different positive attributes while attempting to circumvent their limitations. This new method partially unmixes AVIRIS data, mapping apparent target abundances, in the presence of an arbitrary and unknown spectrally mixed background. It permits the target materials to be present in abundances that drive significant portions of the scene covariance. Furthermore it does not require a priori knowledge of the background material spectral signatures. The challenge is to find the proper projection of the data that hides the background variance while simultaneously maximizing the variance amongst the targets.

The influence of participant characteristics on the relationship between cuff pressure and level of blood flow restriction.

PubMed

Hunt, Julie E A; Stodart, Clare; Ferguson, Richard A

2016-07-01

Previous investigations to establish factors influencing the blood flow restriction (BFR) stimulus have determined cuff pressures required for complete arterial occlusion, which does not reflect the partial restriction prescribed for this training technique. This study aimed to establish characteristics that should be accounted for when prescribing cuff pressures required for partial BFR. Fifty participants were subjected to incremental blood flow restriction of the upper and lower limbs by proximal pneumatic cuff inflation. Popliteal and brachial artery diameter, blood velocity and blood flow was assessed with Doppler ultrasound. Height, body mass, limb circumference, muscle-bone cross-sectional area, adipose thickness (AT) and arterial blood pressure were measured and used in different models of hierarchical linear regression to predict the pressure at which 60 % BFR (partial occlusion) occurred. Combined analysis revealed a difference in cuff pressures required to elicit 60 % BFR in the popliteal (111 ± 12 mmHg) and brachial arteries (101 ± 12 mmHg). MAP (r = 0.58) and AT (r = -0.45) were the largest independent determinants of lower and upper body partial occlusion pressures. However, greater variance was explained by upper and lower limb regression models composed of DBP and BMI (48 %), and arm AT and DBP (30 %), respectively. Limb circumference has limited impact on the cuff pressure required for partial blood flow restriction which is in contrast to its recognised relationship with complete arterial occlusion. The majority of the variance in partial occlusion pressure remains unexplained by the predictor variables assessed in the present study.

Single neuron firing properties impact correlation-based population coding

PubMed Central

Hong, Sungho; Ratté, Stéphanie; Prescott, Steven A.; De Schutter, Erik

2012-01-01

Correlated spiking has been widely observed but its impact on neural coding remains controversial. Correlation arising from co-modulation of rates across neurons has been shown to vary with the firing rates of individual neurons. This translates into rate and correlation being equivalently tuned to the stimulus; under those conditions, correlated spiking does not provide information beyond that already available from individual neuron firing rates. Such correlations are irrelevant and can reduce coding efficiency by introducing redundancy. Using simulations and experiments in rat hippocampal neurons, we show here that pairs of neurons receiving correlated input also exhibit correlations arising from precise spike-time synchronization. Contrary to rate co-modulation, spike-time synchronization is unaffected by firing rate, thus enabling synchrony- and rate-based coding to operate independently. The type of output correlation depends on whether intrinsic neuron properties promote integration or coincidence detection: “ideal” integrators (with spike generation sensitive to stimulus mean) exhibit rate co-modulation whereas “ideal” coincidence detectors (with spike generation sensitive to stimulus variance) exhibit precise spike-time synchronization. Pyramidal neurons are sensitive to both stimulus mean and variance, and thus exhibit both types of output correlation proportioned according to which operating mode is dominant. Our results explain how different types of correlations arise based on how individual neurons generate spikes, and why spike-time synchronization and rate co-modulation can encode different stimulus properties. Our results also highlight the importance of neuronal properties for population-level coding insofar as neural networks can employ different coding schemes depending on the dominant operating mode of their constituent neurons. PMID:22279226

Comparing transformation methods for DNA microarray data

PubMed Central

Thygesen, Helene H; Zwinderman, Aeilko H

2004-01-01

Background When DNA microarray data are used for gene clustering, genotype/phenotype correlation studies, or tissue classification the signal intensities are usually transformed and normalized in several steps in order to improve comparability and signal/noise ratio. These steps may include subtraction of an estimated background signal, subtracting the reference signal, smoothing (to account for nonlinear measurement effects), and more. Different authors use different approaches, and it is generally not clear to users which method they should prefer. Results We used the ratio between biological variance and measurement variance (which is an F-like statistic) as a quality measure for transformation methods, and we demonstrate a method for maximizing that variance ratio on real data. We explore a number of transformations issues, including Box-Cox transformation, baseline shift, partial subtraction of the log-reference signal and smoothing. It appears that the optimal choice of parameters for the transformation methods depends on the data. Further, the behavior of the variance ratio, under the null hypothesis of zero biological variance, appears to depend on the choice of parameters. Conclusions The use of replicates in microarray experiments is important. Adjustment for the null-hypothesis behavior of the variance ratio is critical to the selection of transformation method. PMID:15202953

Comparing transformation methods for DNA microarray data.

PubMed

Thygesen, Helene H; Zwinderman, Aeilko H

2004-06-17

When DNA microarray data are used for gene clustering, genotype/phenotype correlation studies, or tissue classification the signal intensities are usually transformed and normalized in several steps in order to improve comparability and signal/noise ratio. These steps may include subtraction of an estimated background signal, subtracting the reference signal, smoothing (to account for nonlinear measurement effects), and more. Different authors use different approaches, and it is generally not clear to users which method they should prefer. We used the ratio between biological variance and measurement variance (which is an F-like statistic) as a quality measure for transformation methods, and we demonstrate a method for maximizing that variance ratio on real data. We explore a number of transformations issues, including Box-Cox transformation, baseline shift, partial subtraction of the log-reference signal and smoothing. It appears that the optimal choice of parameters for the transformation methods depends on the data. Further, the behavior of the variance ratio, under the null hypothesis of zero biological variance, appears to depend on the choice of parameters. The use of replicates in microarray experiments is important. Adjustment for the null-hypothesis behavior of the variance ratio is critical to the selection of transformation method.

Heart Rate Variability for Evaluating Vigilant Attention in Partial Chronic Sleep Restriction

PubMed Central

Henelius, Andreas; Sallinen, Mikael; Huotilainen, Minna; Müller, Kiti; Virkkala, Jussi; Puolamäki, Kai

2014-01-01

Study Objectives: Examine the use of spectral heart rate variability (HRV) metrics in measuring sleepiness under chronic partial sleep restriction, and identify underlying relationships between HRV, Karolinska Sleepiness Scale ratings (KSS), and performance on the Psychomotor Vigilance Task (PVT). Design: Controlled laboratory study. Setting: Experimental laboratory of the Brain Work Research Centre of the Finnish Institute of Occupational Health, Helsinki, Finland. Participants: Twenty-three healthy young males (mean age ± SD = 23.77 ± 2.29). Interventions: A sleep restriction group (N = 15) was subjected to chronic partial sleep restriction with 4 h sleep for 5 nights. A control group (N = 8) had 8 h sleep on all nights. Measurements and Results: Based on a search over all HRV frequency bands in the range [0.00, 0.40] Hz, the band [0.01, 0.08] Hz showed the highest correlation for HRV–PVT (0.60, 95% confidence interval [0.49, 0.69]) and HRV–KSS (0.33, 95% confidence interval [0.16, 0.46]) for the sleep restriction group; no correlation was found for the control group. We studied the fraction of variance in PVT explained by HRV and a 3-component alertness model, containing circadian and homeostatic processes coupled with sleep inertia, respectively. HRV alone explained 33% of PVT variance. Conclusions: The findings suggest that HRV spectral power reflects vigilant attention in subjects exposed to partial chronic sleep restriction. Citation: Henelius A, Sallinen M, Huotilainen M, Müller K, Virkkala J, Puolamäki K. Heart rate variability for evaluating vigilant attention in partial chronic sleep restriction. SLEEP 2014;37(7):1257-1267. PMID:24987165

Determining a one-tailed upper limit for future sample relative reproducibility standard deviations.

PubMed

McClure, Foster D; Lee, Jung K

2006-01-01

A formula was developed to determine a one-tailed 100p% upper limit for future sample percent relative reproducibility standard deviations (RSD(R),%= 100s(R)/y), where S(R) is the sample reproducibility standard deviation, which is the square root of a linear combination of the sample repeatability variance (s(r)2) plus the sample laboratory-to-laboratory variance (s(L)2), i.e., S(R) = s(L)2, and y is the sample mean. The future RSD(R),% is expected to arise from a population of potential RSD(R),% values whose true mean is zeta(R),% = 100sigmaR, where sigmaR and mu are the population reproducibility standard deviation and mean, respectively.

The response of the SSM/I to the marine environment. Part 2: A parameterization of the effect of the sea surface slope distribution on emission and reflection

NASA Technical Reports Server (NTRS)

Petty, Grant W.; Katsaros, Kristina B.

1994-01-01

Based on a geometric optics model and the assumption of an isotropic Gaussian surface slope distribution, the component of ocean surface microwave emissivity variation due to large-scale surface roughness is parameterized for the frequencies and approximate viewing angle of the Special Sensor Microwave/Imager. Independent geophysical variables in the parameterization are the effective (microwave frequency dependent) slope variance and the sea surface temperature. Using the same physical model, the change in the effective zenith angle of reflected sky radiation arising from large-scale roughness is also parameterized. Independent geophysical variables in this parameterization are the effective slope variance and the atmospheric optical depth at the frequency in question. Both of the above model-based parameterizations are intended for use in conjunction with empirical parameterizations relating effective slope variance and foam coverage to near-surface wind speed. These empirical parameterizations are the subject of a separate paper.

Toward a Bioecological Model of School Engagement: A Biometric Analysis of Gene and Environmental Factors

PubMed Central

Maynard, Brandy R.; Beaver, Kevin M.; Vaughn, Michael G.; DeLisi, Matthew; Roberts, Gregory

2014-01-01

School disengagement is associated with poor academic achievement, dropout, and risk behaviors such as truancy, delinquency, and substance use. Despite empirical research identifying risk correlates of school disengagement across the ecology, it is unclear from which domain these correlates arise. To redress this issue, the current study used intraclass correlation and DeFries-Fulker analyses to longitudinally decompose variance in three domains of engagement (academic, behavioral, and emotional) using data from the National Longitudinal Study of Adolescent Health. Findings suggest that nonshared environmental factors (that is, environmental contexts and experiences that are unique to each sibling) account for approximately half of the variance in indicators of school disengagement when controlling for genetic influences, and that this variance increases as adolescents grow older and rely less on their immediate family. The present study contributes new evidence on the biosocial underpinnings of school engagement and highlights the importance of interventions targeting factors in the nonshared environment. PMID:25525321

A Cosmic Variance Cookbook

NASA Astrophysics Data System (ADS)

Moster, Benjamin P.; Somerville, Rachel S.; Newman, Jeffrey A.; Rix, Hans-Walter

2011-04-01

Deep pencil beam surveys (<1 deg2) are of fundamental importance for studying the high-redshift universe. However, inferences about galaxy population properties (e.g., the abundance of objects) are in practice limited by "cosmic variance." This is the uncertainty in observational estimates of the number density of galaxies arising from the underlying large-scale density fluctuations. This source of uncertainty can be significant, especially for surveys which cover only small areas and for massive high-redshift galaxies. Cosmic variance for a given galaxy population can be determined using predictions from cold dark matter theory and the galaxy bias. In this paper, we provide tools for experiment design and interpretation. For a given survey geometry, we present the cosmic variance of dark matter as a function of mean redshift \\bar{z} and redshift bin size Δz. Using a halo occupation model to predict galaxy clustering, we derive the galaxy bias as a function of mean redshift for galaxy samples of a given stellar mass range. In the linear regime, the cosmic variance of these galaxy samples is the product of the galaxy bias and the dark matter cosmic variance. We present a simple recipe using a fitting function to compute cosmic variance as a function of the angular dimensions of the field, \\bar{z}, Δz, and stellar mass m *. We also provide tabulated values and a software tool. The accuracy of the resulting cosmic variance estimates (δσ v /σ v ) is shown to be better than 20%. We find that for GOODS at \\bar{z}=2 and with Δz = 0.5, the relative cosmic variance of galaxies with m *>1011 M sun is ~38%, while it is ~27% for GEMS and ~12% for COSMOS. For galaxies of m * ~ 1010 M sun, the relative cosmic variance is ~19% for GOODS, ~13% for GEMS, and ~6% for COSMOS. This implies that cosmic variance is a significant source of uncertainty at \\bar{z}=2 for small fields and massive galaxies, while for larger fields and intermediate mass galaxies, cosmic variance is less serious.

Partial Quark-Lepton Universality and Neutrino CP Violation

DOE PAGES

Liao, Jiajun; Marfatia, D.; Whisnant, K.

2015-01-01

We smore » tudy a model with partial quark-lepton universality that can naturally arise in grand unified theories. We find that constraints on the model can be reduced to a single condition on the Dirac CP phase δ in the neutrino sector. Using our current knowledge of the CKM and PMNS mixing matrices, we predict - 32 . 4 ° ≤ δ ≤ 32 . 0 ° at 2 σ .« less

Data mining on long-term barometric data within the ARISE2 project

NASA Astrophysics Data System (ADS)

Hupe, Patrick; Ceranna, Lars; Pilger, Christoph

2016-04-01

The Comprehensive nuclear-Test-Ban Treaty (CTBT) led to the implementation of an international infrasound array network. The International Monitoring System (IMS) network includes 48 certified stations, each providing data for up to 15 years. As part of work package 3 of the ARISE2 project (Atmospheric dynamics Research InfraStructure in Europe, phase 2) the data sets will be statistically evaluated with regard on atmospheric dynamics. The current study focusses on fluctuations of absolute air pressure. Time series have been analysed for 17 monitoring stations which are located all over the world between Greenland and Antarctica along the latitudes to represent different climate zones and characteristic atmospheric conditions. Hence this enables quantitative comparisons between those regions. Analyses are shown including wavelet power spectra, multi-annual time series of average variances with regard to long-wave scales, and spectral densities to derive characteristics and special events. Evaluations reveal periodicities in average variances on 2 to 20 day scale with a maximum in the winter months and a minimum in summer of the respective hemisphere. This basically applies to time series of IMS stations beyond the tropics where the dominance of cyclones and anticyclones changes with seasons. Furthermore, spectral density analyses illustrate striking signals for several dynamic activities within one day, e.g., the semidiurnal tide.

Simultaneous analysis of large INTEGRAL/SPI1 datasets: Optimizing the computation of the solution and its variance using sparse matrix algorithms

NASA Astrophysics Data System (ADS)

Bouchet, L.; Amestoy, P.; Buttari, A.; Rouet, F.-H.; Chauvin, M.

2013-02-01

Nowadays, analyzing and reducing the ever larger astronomical datasets is becoming a crucial challenge, especially for long cumulated observation times. The INTEGRAL/SPI X/γ-ray spectrometer is an instrument for which it is essential to process many exposures at the same time in order to increase the low signal-to-noise ratio of the weakest sources. In this context, the conventional methods for data reduction are inefficient and sometimes not feasible at all. Processing several years of data simultaneously requires computing not only the solution of a large system of equations, but also the associated uncertainties. We aim at reducing the computation time and the memory usage. Since the SPI transfer function is sparse, we have used some popular methods for the solution of large sparse linear systems; we briefly review these methods. We use the Multifrontal Massively Parallel Solver (MUMPS) to compute the solution of the system of equations. We also need to compute the variance of the solution, which amounts to computing selected entries of the inverse of the sparse matrix corresponding to our linear system. This can be achieved through one of the latest features of the MUMPS software that has been partly motivated by this work. In this paper we provide a brief presentation of this feature and evaluate its effectiveness on astrophysical problems requiring the processing of large datasets simultaneously, such as the study of the entire emission of the Galaxy. We used these algorithms to solve the large sparse systems arising from SPI data processing and to obtain both their solutions and the associated variances. In conclusion, thanks to these newly developed tools, processing large datasets arising from SPI is now feasible with both a reasonable execution time and a low memory usage.

Half a Gift Is Not Half-Hearted: A Giver-Receiver Asymmetry in the Thoughtfulness of Partial Gifts.

PubMed

Kupor, Daniella; Flynn, Frank; Norton, Michael I

2017-12-01

Four studies document an asymmetry in givers' and receivers' evaluations of gifts: Givers underestimate the extent to which receivers perceive partial (but more desirable) gifts to be thoughtful, valuable, and worthy of appreciation. Study 1 documents this asymmetry and suggests that givers underestimate the extent to which partial gifts signal thoughtfulness to receivers. Study 2 replicates this asymmetry in the context of a real gift exchange among friends. Study 3 shows that this asymmetry arises because givers believe that purchasing partial gifts is a greater violation of gift-giving norms than do receivers, leading givers to expect that partial gifts will damage receivers' perceptions of a gift's value. Study 4 offers an intervention that induces givers to select the (partial) gifts that receivers prefer more than givers expect: framing a gift's separate components as complete units.

Oxygen Partial Pressure and Oxygen Concentration Flammability: Can They Be Correlated?

NASA Technical Reports Server (NTRS)

Harper, Susana A.; Juarez, Alfredo; Perez, Horacio, III; Hirsch, David B.; Beeson, Harold D.

2016-01-01

NASA possesses a large quantity of flammability data performed in ISS airlock (30% Oxygen 526mmHg) and ISS cabin (24.1% Oxygen 760 mmHg) conditions. As new programs develop, other oxygen and pressure conditions emerge. In an effort to apply existing data, the question arises: Do equivalent oxygen partial pressures perform similarly with respect to flammability? This paper evaluates how material flammability performance is impacted from both the Maximum Oxygen Concentration (MOC) and Maximum Total Pressures (MTP) perspectives. From these studies, oxygen partial pressures can be compared for both the MOC and MTP methods to determine the role of partial pressure in material flammability. This evaluation also assesses the influence of other variables on flammability performance. The findings presented in this paper suggest flammability is more dependent on oxygen concentration than equivalent partial pressure.

Shifting patterns of variance in adolescent alcohol use: Testing consumption as a developing trait-state.

PubMed

Nealis, Logan J; Thompson, Kara D; Krank, Marvin D; Stewart, Sherry H

2016-04-01

While average rates of change in adolescent alcohol consumption are frequently studied, variability arising from situational and dispositional influences on alcohol use has been comparatively neglected. We used variance decomposition to test differences in variability resulting from year-to-year fluctuations in use (i.e., state-like) and from stable individual differences (i.e., trait-like) using data from the Project on Adolescent Trajectories and Health (PATH), a cohort-sequential study spanning grades 7 to 11 using three cohorts starting in grades seven, eight, and nine, respectively. We tested variance components for alcohol volume, frequency, and quantity in the overall sample, and changes in components over time within each cohort. Sex differences were tested. Most variability in alcohol use reflected state-like variation (47-76%), with a relatively smaller proportion of trait-like variation (19-36%). These proportions shifted across cohorts as youth got older, with increases in trait-like variance from early adolescence (14-30%) to later adolescence (30-50%). Trends were similar for males and females, although females showed higher trait-like variance in alcohol frequency than males throughout development (26-43% vs. 11-25%). For alcohol volume and frequency, males showed the greatest increase in trait-like variance earlier in development (i.e., grades 8-10) compared to females (i.e., grades 9-11). The relative strength of situational and dispositional influences on adolescent alcohol use has important implications for preventative interventions. Interventions should ideally target problematic alcohol use before it becomes more ingrained and trait-like. Copyright © 2015 Elsevier Ltd. All rights reserved.

Discrimination of shot-noise-driven Poisson processes by external dead time - Application of radioluminescence from glass

NASA Technical Reports Server (NTRS)

Saleh, B. E. A.; Tavolacci, J. T.; Teich, M. C.

1981-01-01

Ways in which dead time can be used to constructively enhance or diminish the effects of point processes that display bunching in the shot-noise-driven doubly stochastic Poisson point process (SNDP) are discussed. Interrelations between photocount bunching arising in the SNDP and the antibunching character arising from dead-time effects are investigated. It is demonstrated that the dead-time-modified count mean and variance for an arbitrary doubly stochastic Poisson point process can be obtained from the Laplace transform of the single-fold and joint-moment-generating functions for the driving rate process. The theory is in good agreement with experimental values for radioluminescence radiation in fused silica, quartz, and glass, and the process has many applications in pulse, particle, and photon detection.

Modelling skin penetration using the Laplace transform technique.

PubMed

Anissimov, Y G; Watkinson, A

2013-01-01

The Laplace transform is a convenient mathematical tool for solving ordinary and partial differential equations. The application of this technique to problems arising in drug penetration through the skin is reviewed in this paper. © 2013 S. Karger AG, Basel.

Contrast model for three-dimensional vehicles in natural lighting and search performance analysis

NASA Astrophysics Data System (ADS)

Witus, Gary; Gerhart, Grant R.; Ellis, R. Darin

2001-09-01

Ground vehicles in natural lighting tend to have significant and systematic variation in luminance through the presented area. This arises, in large part, from the vehicle surfaces having different orientations and shadowing relative to the source of illumination and the position of the observer. These systematic differences create the appearance of a structured 3D object. The 3D appearance is an important factor in search, figure-ground segregation, and object recognition. We present a contrast metric to predict search and detection performance that accounts for the 3D structure. The approach first computes the contrast of the front (or rear), side, and top surfaces. The vehicle contrast metric is the area-weighted sum of the absolute values of the contrasts of the component surfaces. The 3D structure contrast metric, together with target height, account for more than 80% of the variance in probability of detection and 75% of the variance in search time. When false alarm effects are discounted, they account for 89% of the variance in probability of detection and 95% of the variance in search time. The predictive power of the signature metric, when calibrated to half the data and evaluated against the other half, is 90% of the explanatory power.

Contractions from grading

NASA Astrophysics Data System (ADS)

Krishnan, Chethan; Raju, Avinash

2018-04-01

We note that large classes of contractions of algebras that arise in physics can be understood purely algebraically via identifying appropriate Zm-gradings (and their generalizations) on the parent algebra. This includes various types of flat space/Carroll limits of finite and infinite dimensional (A)dS algebras, as well as Galilean and Galilean conformal algebras. Our observations can be regarded as providing a natural context for the Grassmann approach of Krishnan et al. [J. High Energy Phys. 2014(3), 36]. We also introduce a related notion, which we call partial grading, that arises naturally in this context.

Methods for presentation and display of multivariate data

NASA Technical Reports Server (NTRS)

Myers, R. H.

1981-01-01

Methods for the presentation and display of multivariate data are discussed with emphasis placed on the multivariate analysis of variance problems and the Hotelling T(2) solution in the two-sample case. The methods utilize the concepts of stepwise discrimination analysis and the computation of partial correlation coefficients.

Mother-Child Joint Writing and Storybook Reading: Relations with Literacy among Low SES Kindergartners.

ERIC Educational Resources Information Center

Aram, Dorit; Levin, Iris

2002-01-01

Examined relationship of maternal mediation in joint writing and of storybook reading with emergent literacy among low-SES kindergartners. Found that after partialling out home environment measures and storybook reading, maternal writing mediation explained added variance for children's word writing/recognition and phonological awareness.…

Applying species-tree analyses to deep phylogenetic histories: challenges and potential suggested from a survey of empirical phylogenetic studies.

PubMed

Lanier, Hayley C; Knowles, L Lacey

2015-02-01

Coalescent-based methods for species-tree estimation are becoming a dominant approach for reconstructing species histories from multi-locus data, with most of the studies examining these methodologies focused on recently diverged species. However, deeper phylogenies, such as the datasets that comprise many Tree of Life (ToL) studies, also exhibit gene-tree discordance. This discord may also arise from the stochastic sorting of gene lineages during the speciation process (i.e., reflecting the random coalescence of gene lineages in ancestral populations). It remains unknown whether guidelines regarding methodologies and numbers of loci established by simulation studies at shallow tree depths translate into accurate species relationships for deeper phylogenetic histories. We address this knowledge gap and specifically identify the challenges and limitations of species-tree methods that account for coalescent variance for deeper phylogenies. Using simulated data with characteristics informed by empirical studies, we evaluate both the accuracy of estimated species trees and the characteristics associated with recalcitrant nodes, with a specific focus on whether coalescent variance is generally responsible for the lack of resolution. By determining the proportion of coalescent genealogies that support a particular node, we demonstrate that (1) species-tree methods account for coalescent variance at deep nodes and (2) mutational variance - not gene-tree discord arising from the coalescent - posed the primary challenge for accurate reconstruction across the tree. For example, many nodes were accurately resolved despite predicted discord from the random coalescence of gene lineages and nodes with poor support were distributed across a range of depths (i.e., they were not restricted to a particular recent divergences). Given their broad taxonomic scope and large sampling of taxa, deep level phylogenies pose several potential methodological complications including difficulties with MCMC convergence and estimation of requisite population genetic parameters for coalescent-based approaches. Despite these difficulties, the findings generally support the utility of species-tree analyses for the estimation of species relationships throughout the ToL. We discuss strategies for successful application of species-tree approaches to deep phylogenies. Copyright © 2014 Elsevier Inc. All rights reserved.

Real versus Artificial Variation in the Thermal Sensitivity of Biological Traits.

PubMed

Pawar, Samraat; Dell, Anthony I; Savage, Van M; Knies, Jennifer L

2016-02-01

Whether the thermal sensitivity of an organism's traits follows the simple Boltzmann-Arrhenius model remains a contentious issue that centers around consideration of its operational temperature range and whether the sensitivity corresponds to one or a few underlying rate-limiting enzymes. Resolving this issue is crucial, because mechanistic models for temperature dependence of traits are required to predict the biological effects of climate change. Here, by combining theory with data on 1,085 thermal responses from a wide range of traits and organisms, we show that substantial variation in thermal sensitivity (activation energy) estimates can arise simply because of variation in the range of measured temperatures. Furthermore, when thermal responses deviate systematically from the Boltzmann-Arrhenius model, variation in measured temperature ranges across studies can bias estimated activation energy distributions toward higher mean, median, variance, and skewness. Remarkably, this bias alone can yield activation energies that encompass the range expected from biochemical reactions (from ~0.2 to 1.2 eV), making it difficult to establish whether a single activation energy appropriately captures thermal sensitivity. We provide guidelines and a simple equation for partially correcting for such artifacts. Our results have important implications for understanding the mechanistic basis of thermal responses of biological traits and for accurately modeling effects of variation in thermal sensitivity on responses of individuals, populations, and ecological communities to changing climatic temperatures.

Influence of disorder on the signature of the pseudogap and multigap superconducting behavior in FeSe

NASA Astrophysics Data System (ADS)

Rößler, Sahana; Huang, Chien-Lung; Jiao, Lin; Koz, Cevriye; Schwarz, Ulrich; Wirth, Steffen

2018-03-01

We investigated several FeSe single crystals grown by two different methods by utilizing experimental techniques, namely, resistivity, magnetoresistance, specific heat, scanning tunneling microscopy, and spectroscopy. The residual resistivity ratio (RRR) shows systematic differences between samples grown by chemical vapor transport and flux vapor transport, indicating variance in the amount of scattering centers. Although the superconducting transition temperature Tc is not directly related to RRR, our study evidences subtle differences in the features of an incipient ordering mode related to a depletion of density of states at the Fermi level. For instance, the onset temperature of anisotropic spin fluctuations at T*≈75 K, and the temperature of the opening up of a partial gap in the density of states at T**≈30 K, are not discernible in the samples with lower RRR. Further, we show that the functional dependence of the electronic specific heat below 2 K, which allows us to determine the nodal features as well as the small superconducting gap, differs significantly in crystals grown by these two different methods. Our investigation suggests that some of the controversies about the driving mechanism for the superconducting gap or its structure and symmetry are related to minute differences in the crystals arising due to the growth techniques used and the total amount of scattering centers present in the sample.

Investigation of the variance and spectral anisotropies of the solar wind turbulence with multiple point spacecraft observations

NASA Astrophysics Data System (ADS)

Vech, Daniel; Chen, Christopher

2016-04-01

One of the most important features of the plasma turbulence is the anisotropy, which arises due to the presence of the magnetic field. The understanding of the anisotropy is particularly important to reveal how the turbulent cascade operates. It is well known that anisotropy exists with respect to the mean magnetic field, however recent theoretical studies suggested anisotropy with respect to the radial direction. The purpose of this study is to investigate the variance and spectral anisotropies of the solar wind turbulence with multiple point spacecraft observations. The study includes the Advanced Composition Analyzer (ACE), WIND and Cluster spacecraft data. The second order structure functions are derived for two different spacecraft configurations: when the pair of spacecraft are separated radially (with respect to the spacecraft -Sun line) and when they are separated along the transverse direction. We analyze the effect of the different sampling directions on the variance anisotropy, global spectral anisotropy, local 3D spectral anisotropy and discuss the implications for our understanding of solar wind turbulence.

Anisotropic singularities in modified gravity models

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

Figueiro, Michele Ferraz; Saa, Alberto; Departamento de Matematica Aplicada, IMECC-UNICAMP, C.P. 6065, 13083-859 Campinas, SP

2009-09-15

We show that the common singularities present in generic modified gravity models governed by actions of the type S={integral}d{sup 4}x{radical}(-g)f(R,{phi},X), with X=-(1/2)g{sup ab}{partial_derivative}{sub a}{phi}{partial_derivative}{sub b}{phi}, are essentially the same anisotropic instabilities associated to the hypersurface F({phi})=0 in the case of a nonminimal coupling of the type F({phi})R, enlightening the physical origin of such singularities that typically arise in rather complex and cumbersome inhomogeneous perturbation analyses. We show, moreover, that such anisotropic instabilities typically give rise to dynamically unavoidable singularities, precluding completely the possibility of having physically viable models for which the hypersurface ({partial_derivative}f/{partial_derivative}R)=0 is attained. Some examples are explicitly discussed.

Relationship authenticity partially mediates the effects of attachment on relationship satisfaction.

PubMed

Rasco, Danney; Warner, Rebecca M

2017-01-01

Individuals with anxious and avoidant attachment tend to experience less satisfaction in their relationships. Past research suggests the negative effects of attachment on relationship satisfaction may be partially mediated by self-disclosure and self-concealment; the present study evaluated relationship authenticity as a potential additional mediator. Confirmatory factor analysis indicated that relationship authenticity is distinct from self-disclosure and self-concealment. Relationship authenticity predicted additional variance in relationship satisfaction controlling for attachment, self-disclosure, and self-concealment. The results were consistent with relationship authenticity, along with self-disclosure and self-concealment, partially mediating the effects of attachment on relationship satisfaction. These findings suggest that relationship authenticity may play a unique role in understanding how attachment influences relationship satisfaction. Theoretical and clinical implications are discussed.

Risk Adjustment for a Children's Capitation Rate

PubMed Central

Newhouse, Joseph P.; Sloss, Elizabeth M.; Manning, Willard G.; Keeler, Emmett B.

1993-01-01

Few capitation arrangements vary premiums by a child's health characteristics, yielding an incentive to discriminate against children with predictably high expenditures from chronic diseases. In this article, we explore risk adjusters for the 35 percent of the variance in annual outpatient expenditure we find to be potentially predictable. Demographic factors such as age and gender only explain 5 percent of such variance; health status measures explain 25 percent, prior use and health status measures together explain 65 to 70 percent. The profit from risk selection falls less than proportionately with improved ability to adjust for risk. Partial capitation rates may be necessary to mitigate skimming and dumping. PMID:10133708

Risk adjustment for a children's capitation rate.

PubMed

Newhouse, J P; Sloss, E M; Manning, W G; Keeler, E B

1993-01-01

Few capitation arrangements vary premiums by a child's health characteristics, yielding an incentive to discriminate against children with predictably high expenditures from chronic diseases. In this article, we explore risk adjusters for the 35 percent of the variance in annual out-patient expenditure we find to be potentially predictable. Demographic factors such as age and gender only explain 5 percent of such variance; health status measures explain 25 percent, prior use and health status measures together explain 65 to 70 percent. The profit from risk selection falls less than proportionately with improved ability to adjust for risk. Partial capitation rates may be necessary to mitigate skimming and dumping.

Tests of Hypotheses Arising In the Correlated Random Coefficient Model*

PubMed Central

Heckman, James J.; Schmierer, Daniel

2010-01-01

This paper examines the correlated random coefficient model. It extends the analysis of Swamy (1971), who pioneered the uncorrelated random coefficient model in economics. We develop the properties of the correlated random coefficient model and derive a new representation of the variance of the instrumental variable estimator for that model. We develop tests of the validity of the correlated random coefficient model against the null hypothesis of the uncorrelated random coefficient model. PMID:21170148

Widths of transverse momentum distributions in intermediate-energy heavy-ion collisions.

PubMed

Khan, F; Townsend, L W

1993-08-01

The need to include dynamical collision momentum transfer contributions, arising from interacting nuclear and Coulomb fields, to estimates of fragment momentum distributions is discussed. Methods based upon an optical potential model are presented. Comparisons with recent experimental data of the Siegen group for variances of transverse momentum distributions for gold nuclei at 980 A MeV fragmenting on silver foil and plastic nuclear track detector targets are made. The agreement between theory and experiment is good.

Global Regularity for Several Incompressible Fluid Models with Partial Dissipation

NASA Astrophysics Data System (ADS)

Wu, Jiahong; Xu, Xiaojing; Ye, Zhuan

2017-09-01

This paper examines the global regularity problem on several 2D incompressible fluid models with partial dissipation. They are the surface quasi-geostrophic (SQG) equation, the 2D Euler equation and the 2D Boussinesq equations. These are well-known models in fluid mechanics and geophysics. The fundamental issue of whether or not they are globally well-posed has attracted enormous attention. The corresponding models with partial dissipation may arise in physical circumstances when the dissipation varies in different directions. We show that the SQG equation with either horizontal or vertical dissipation always has global solutions. This is in sharp contrast with the inviscid SQG equation for which the global regularity problem remains outstandingly open. Although the 2D Euler is globally well-posed for sufficiently smooth data, the associated equations with partial dissipation no longer conserve the vorticity and the global regularity is not trivial. We are able to prove the global regularity for two partially dissipated Euler equations. Several global bounds are also obtained for a partially dissipated Boussinesq system.

Organizational determinants of efficiency and effectiveness in mental health partial care programs.

PubMed Central

Schinnar, A P; Kamis-Gould, E; Delucia, N; Rothbard, A B

1990-01-01

The use of partial care as a treatment modality for mentally ill patients, particularly the chronically mentally ill, has greatly increased. However, research into what constitutes a "good" program has been scant. This article reports on an evaluation study of staff productivity, cost efficiency, and service effectiveness of adult partial care programs carried out in New Jersey in fiscal year 1984/1985. Five program performance indexes are developed based on comparisons of multiple measures of resources, service activities, and client outcomes. These are used to test various hypotheses regarding the effect of organizational and fiscal variables on partial care program efficiency and effectiveness. The four issues explored are: auspices, organizational complexity, service mix, and fiscal control by the state. These were found to explain about half of the variance in program performance. In addition, partial care programs demonstrating midlevel performance with regard to productivity and efficiency were observed to be the most effective, implying a possible optimal level of efficiency at which effectiveness is maximized. PMID:2113046

Generative Inferences Based on Learned Relations

ERIC Educational Resources Information Center

Chen, Dawn; Lu, Hongjing; Holyoak, Keith J.

2017-01-01

A key property of relational representations is their "generativity": From partial descriptions of relations between entities, additional inferences can be drawn about other entities. A major theoretical challenge is to demonstrate how the capacity to make generative inferences could arise as a result of learning relations from…

Four-Mode Squeezing For Optical Communications

NASA Technical Reports Server (NTRS)

Schumaker, Bonny L.

1989-01-01

Experiments demonstrated potential of four-mode squeezing for increasing immunity to noise in fiber-optical communication systems and interferometric devices. Four-mode squeezing reduces quantum noise more than ordinary squeezing and provides partial immunity to non-quantum-mechanical phase noise arising in such media as optical fibers.

A three operator split-step method covering a larger set of non-linear partial differential equations

NASA Astrophysics Data System (ADS)

Zia, Haider

2017-06-01

This paper describes an updated exponential Fourier based split-step method that can be applied to a greater class of partial differential equations than previous methods would allow. These equations arise in physics and engineering, a notable example being the generalized derivative non-linear Schrödinger equation that arises in non-linear optics with self-steepening terms. These differential equations feature terms that were previously inaccessible to model accurately with low computational resources. The new method maintains a 3rd order error even with these additional terms and models the equation in all three spatial dimensions and time. The class of non-linear differential equations that this method applies to is shown. The method is fully derived and implementation of the method in the split-step architecture is shown. This paper lays the mathematical ground work for an upcoming paper employing this method in white-light generation simulations in bulk material.

PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENTOF DUMPING SYNDROME AND ITS RELATION TO BARIATRIC SURGERY

PubMed Central

CHAVES, Yasmin da Silva; DESTEFANI, Afrânio Côgo

2016-01-01

ABSTRACT Introduction The dumping syndrome is frequent in bariatric surgery. It is probably the most common syndrome following partial or complete gastrectomy. Its prevalence in partial gastrectomy can reach up to 50%, thus it can be a significant complication arising from some types of bariatric surgeries. Objective: Critical analysis on dumping syndrome, its pathophysiology, diagnosis and treatment. Methods: A literature review was performed using the key words: 'dumping syndrome', 'bariatric surgery' and 'rapid dumping syndrome'. Inclusion criteria were: books, original works, case reports and meta-analyzes, and the exclusion criterion was literature review. Concerning the publication time, articles were screened between 1960 and May 2015. Results: The dumping syndrome is complication arising from obesity surgeries, but also can be a result of vagus nerve damage. Diagnosis is done primarily through the use of questionnaires based on scores. Conclusion: The Sigstad score and Arts survey are valid means for assessing the dumping syndrome. Initial therapy consists in the adoption of dietary measures, short acting drugs administration. PMID:27683791

Ambiguities in model-independent partial-wave analysis

NASA Astrophysics Data System (ADS)

Krinner, F.; Greenwald, D.; Ryabchikov, D.; Grube, B.; Paul, S.

2018-06-01

Partial-wave analysis is an important tool for analyzing large data sets in hadronic decays of light and heavy mesons. It commonly relies on the isobar model, which assumes multihadron final states originate from successive two-body decays of well-known undisturbed intermediate states. Recently, analyses of heavy-meson decays and diffractively produced states have attempted to overcome the strong model dependences of the isobar model. These analyses have overlooked that model-independent, or freed-isobar, partial-wave analysis can introduce mathematical ambiguities in results. We show how these ambiguities arise and present general techniques for identifying their presence and for correcting for them. We demonstrate these techniques with specific examples in both heavy-meson decay and pion-proton scattering.

Tests for a disease-susceptibility locus allowing for an inbreeding coefficient (F).

PubMed

Song, Kijoung; Elston, Robert C

2003-11-01

We begin by discussing the false positive test results that arise because of cryptic relatedness and population substructure when testing a disease susceptibility locus. We extend and evaluate the Hardy-Weinberg disequilibrium (HWD) method, allowing for an inbreeding coefficient (F) in a similar way that Devlin and Roeder (1999) allowed for inbreeding in a case-control study. Then we compare the HWD measure and the common direct measure of linkage disequilibrium, both when there is no population substructure (F = 0) and when there is population substructure (F not = 0), for a single marker. The HWD test statistic gives rise to false positives caused by population stratification. These false positives can be controlled by adjusting the test statistic for the amount of variance inflation caused by the inbreeding coefficient (F). The power loss for the HWD test that arises when controlling for population structure is much less than that which arises for the common direct measure of linkage disequilibrium. However, in the multiplicative model, the HWD test has virtually no power even when allowing for non-zero F.

Cautionary Note on Reporting Eta-Squared Values from Multifactor ANOVA Designs

ERIC Educational Resources Information Center

Pierce, Charles A.; Block, Richard A.; Aguinis, Herman

2004-01-01

The authors provide a cautionary note on reporting accurate eta-squared values from multifactor analysis of variance (ANOVA) designs. They reinforce the distinction between classical and partial eta-squared as measures of strength of association. They provide examples from articles published in premier psychology journals in which the authors…

Meta-Analysis for Primary and Secondary Data Analysis: The Super-Experiment Metaphor.

ERIC Educational Resources Information Center

Jackson, Sally

1991-01-01

Considers the relation between meta-analysis statistics and analysis of variance statistics. Discusses advantages and disadvantages as a primary data analysis tool. Argues that the two approaches are partial paraphrases of one another. Advocates an integrative approach that introduces the best of meta-analytic thinking into primary analysis…

A mediational model of racial discrimination and alcohol-related problems among african american college students.

PubMed

Boynton, Marcella H; O'Hara, Ross E; Covault, Jonathan; Scott, Denise; Tennen, Howard

2014-03-01

Racial discrimination has been identified as an important predictor of alcohol-related outcomes for African Americans. The goal of the current study was to extend previously found links between lifetime discrimination, alcohol use, and alcohol problems as well as to elucidate the affective mechanisms underlying these associations, as moderated by gender. A multiple-groups structural equation model was computed using survey data collected from 619 students from a historically Black college/university. The final model provided excellent fit to the data, explaining 6% of the variance in alcohol consumption and 37% of the variance in alcohol problems. Discrimination was a significant predictor of alcohol-related problems but not, by and large, level of use. For men, anger-but not discrimination-specific anger-was a significant partial mediator of the link between discrimination and both alcohol use and alcohol problems. Depression partially mediated the link between discrimination and alcohol problems for both men and women. The results suggest that, for African Americans whose drinking leads to drinking-related problems, discrimination and poor affective self-regulation are highly relevant and predictive factors, especially for men.

Internal and surface waves in vibrofluidized granular materials: Role of cohesion

NASA Astrophysics Data System (ADS)

Huang, Kai

2018-05-01

Wave phenomena in vibrofluidized dry and partially wet granular materials confined in a quasi-two-dimensional geometry are investigated with numerical simulations considering individual particles as hard spheres. Short-ranged cohesive interactions arising from the formation of liquid bridges between adjacent particles are modeled by changing the velocity-dependent coefficient of restitution. Such a change effectively suppresses the formation of surface waves, in agreement with previous experimental observations. The difference in pattern creation arises from the suppressed momentum transfer due to wetting and it can be quantitatively understood from an analysis of binary impacts.

A note on the solutions of some nonlinear equations arising in third-grade fluid flows: an exact approach.

PubMed

Aziz, Taha; Mahomed, F M

2014-01-01

In this communication, we utilize some basic symmetry reductions to transform the governing nonlinear partial differential equations arising in the study of third-grade fluid flows into ordinary differential equations. We obtain some simple closed-form steady-state solutions of these reduced equations. Our solutions are valid for the whole domain [0,∞) and also satisfy the physical boundary conditions. We also present the numerical solutions for some of the underlying equations. The graphs corresponding to the essential physical parameters of the flow are presented and discussed.

A Note on the Solutions of Some Nonlinear Equations Arising in Third-Grade Fluid Flows: An Exact Approach

PubMed Central

Mahomed, F. M.

2014-01-01

In this communication, we utilize some basic symmetry reductions to transform the governing nonlinear partial differential equations arising in the study of third-grade fluid flows into ordinary differential equations. We obtain some simple closed-form steady-state solutions of these reduced equations. Our solutions are valid for the whole domain [0,∞) and also satisfy the physical boundary conditions. We also present the numerical solutions for some of the underlying equations. The graphs corresponding to the essential physical parameters of the flow are presented and discussed. PMID:25143962

The role of executive functioning in memory performance in pediatric focal epilepsy

PubMed Central

Sepeta, Leigh N.; Casaletto, Kaitlin Blackstone; Terwilliger, Virginia; Facella-Ervolini, Joy; Sady, Maegan; Mayo, Jessica; Gaillard, William D.; Berl, Madison M.

2016-01-01

Objective Learning and memory are essential for academic success and everyday functioning, but the pattern of memory skills and its relationship to executive functioning in children with focal epilepsy is not fully delineated. We address a gap in the literature by examining the relationship between memory and executive functioning in a pediatric focal epilepsy population. Methods Seventy children with focal epilepsy and 70 typically developing children matched on age, intellectual functioning, and gender underwent neuropsychological assessment, including measures of intelligence (WASI/DAS), as well as visual (CMS Dot Locations) and verbal episodic memory (WRAML Story Memory and CVLT-C). Executive functioning was measured directly (WISC-IV Digit Span Backward; CELF-IV Recalling Sentences) and by parent report (Behavior Rating Inventory of Executive Function (BRIEF)). Results Children with focal epilepsy had lower delayed free recall scores than controls across visual and verbal memory tasks (p = 0.02; partial η2 = .12). In contrast, recognition memory performance was similar for patients and controls (p = 0.36; partial η2 = .03). Children with focal epilepsy demonstrated difficulties in working memory (p = 0.02; partial η2 = .08) and planning/organization (p = 0.02) compared to controls. Working memory predicted 9–19% of the variance in delayed free recall for verbal and visual memory; organization predicted 9–10% of the variance in verbal memory. Patients with both left and right focal epilepsy demonstrated more difficulty on verbal versus visual tasks (p = 0.002). Memory performance did not differ by location of seizure foci (temporal vs. extra-temporal, frontal vs. extra-frontal). Significance Children with focal epilepsy demonstrated memory ability within age-level expectations, but delayed free recall was inefficient compared to typically developing controls. Memory difficulties were not related to general cognitive impairment or seizure localization. Executive functioning accounted for significant variance in memory performance, suggesting that poor executive control negatively influences memory retrieval. PMID:28111742

Upper-Division Student Difficulties with Separation of Variables

ERIC Educational Resources Information Center

Wilcox, Bethany R.; Pollock, Steven J.

2015-01-01

Separation of variables can be a powerful technique for solving many of the partial differential equations that arise in physics contexts. Upper-division physics students encounter this technique in multiple topical areas including electrostatics and quantum mechanics. To better understand the difficulties students encounter when utilizing the…

Partial differential equation models in macroeconomics.

PubMed

Achdou, Yves; Buera, Francisco J; Lasry, Jean-Michel; Lions, Pierre-Louis; Moll, Benjamin

2014-11-13

The purpose of this article is to get mathematicians interested in studying a number of partial differential equations (PDEs) that naturally arise in macroeconomics. These PDEs come from models designed to study some of the most important questions in economics. At the same time, they are highly interesting for mathematicians because their structure is often quite difficult. We present a number of examples of such PDEs, discuss what is known about their properties, and list some open questions for future research. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Stratospheric Assimilation of Chemical Tracer Observations Using a Kalman Filter. Pt. 2; Chi-Square Validated Results and Analysis of Variance and Correlation Dynamics

NASA Technical Reports Server (NTRS)

Menard, Richard; Chang, Lang-Ping

1998-01-01

A Kalman filter system designed for the assimilation of limb-sounding observations of stratospheric chemical tracers, which has four tunable covariance parameters, was developed in Part I (Menard et al. 1998) The assimilation results of CH4 observations from the Cryogenic Limb Array Etalon Sounder instrument (CLAES) and the Halogen Observation Experiment instrument (HALOE) on board of the Upper Atmosphere Research Satellite are described in this paper. A robust (chi)(sup 2) criterion, which provides a statistical validation of the forecast and observational error covariances, was used to estimate the tunable variance parameters of the system. In particular, an estimate of the model error variance was obtained. The effect of model error on the forecast error variance became critical after only three days of assimilation of CLAES observations, although it took 14 days of forecast to double the initial error variance. We further found that the model error due to numerical discretization as arising in the standard Kalman filter algorithm, is comparable in size to the physical model error due to wind and transport modeling errors together. Separate assimilations of CLAES and HALOE observations were compared to validate the state estimate away from the observed locations. A wave-breaking event that took place several thousands of kilometers away from the HALOE observation locations was well captured by the Kalman filter due to highly anisotropic forecast error correlations. The forecast error correlation in the assimilation of the CLAES observations was found to have a structure similar to that in pure forecast mode except for smaller length scales. Finally, we have conducted an analysis of the variance and correlation dynamics to determine their relative importance in chemical tracer assimilation problems. Results show that the optimality of a tracer assimilation system depends, for the most part, on having flow-dependent error correlation rather than on evolving the error variance.

Risk-sensitivity and the mean-variance trade-off: decision making in sensorimotor control

PubMed Central

Nagengast, Arne J.; Braun, Daniel A.; Wolpert, Daniel M.

2011-01-01

Numerous psychophysical studies suggest that the sensorimotor system chooses actions that optimize the average cost associated with a movement. Recently, however, violations of this hypothesis have been reported in line with economic theories of decision-making that not only consider the mean payoff, but are also sensitive to risk, that is the variability of the payoff. Here, we examine the hypothesis that risk-sensitivity in sensorimotor control arises as a mean-variance trade-off in movement costs. We designed a motor task in which participants could choose between a sure motor action that resulted in a fixed amount of effort and a risky motor action that resulted in a variable amount of effort that could be either lower or higher than the fixed effort. By changing the mean effort of the risky action while experimentally fixing its variance, we determined indifference points at which participants chose equiprobably between the sure, fixed amount of effort option and the risky, variable effort option. Depending on whether participants accepted a variable effort with a mean that was higher, lower or equal to the fixed effort, they could be classified as risk-seeking, risk-averse or risk-neutral. Most subjects were risk-sensitive in our task consistent with a mean-variance trade-off in effort, thereby, underlining the importance of risk-sensitivity in computational models of sensorimotor control. PMID:21208966

Relationships between genotype x environment interactions and rank orders for a set of genotypes tested in different environments.

PubMed

Hühn, M; Lotito, S; Piepho, H P

1993-09-01

Multilocation trials in plant breeding lead to cross-classified data sets with rows=genotypes and columns=environments, where the breeder is particularly interested in the rank orders of the genotypes in the different environments. Non-identical rank orders are the result of genotype x environment interactions. Not every interaction, however, causes rank changes among the genotypes (rank-interaction). From a breeder's point of view, interaction is tolerable only as long as it does not affect the rank orders. Therefore, the question arises of under which circumstances does interaction become rank-interaction. This paper contributes to our understanding of this topic. In our study we emphasized the detection of relationships between the similarity of the rank orders (measured by Kendall's coefficient of concordance W) and the functions of the diverse variance components (genotypes, environments, interaction, error). On the basis of extensive data sets on different agricultural crops (faba bean, fodder beet, sugar beet, oats, winter rape) obtained from registration trials (1985-1989) carried out in the Federal Republic of Germany, we obtained the following as main result: W ≅ σ 2 (g) /(σ 2 (g) + σ 2 (v) ) where σ 2 (g) =genotypic variance and σ 2 (v) = σ 2 (ge) + σ 2 (o) /L with σ 2 (ge) =interaction variance, σ 2 (o) =error variance and L=number of replications.

Effects of asynchrony and ear of presentation on the pitch of mistuned partials in harmonic and frequency-shifted complex tones.

PubMed

Brunstrom, J M; Roberts, B

2001-07-01

When a partial of a periodic complex is mistuned, its change in pitch is greater than expected. Two experiments examined whether these partial-pitch shifts are related to the computation of global pitch. In experiment 1, stimuli were either harmonic or frequency-shifted (25% of F0) complexes. One partial was mistuned by +/- 4% and played with leading and lagging portions of 500 ms each, relative to the other components (1 s), in both monaural and dichotic contexts. Subjects indicated whether the mistuned partial was higher or lower in pitch when concurrent with the other components. Responses were positively correlated with the direction of mistuning in all conditions. In experiment 2, stimuli from each condition were compared with synchronous equivalents. Subjects matched a pure tone to the pitch of the mistuned partial (component 4). The results showed that partial-pitch shifts are not reduced in size by asynchrony. Similar asynchronies are known to produce a near-exclusion of a mistuned partial from the global-pitch computation. This mismatch indicates that global and partial pitch are derived from different processes. The similarity of the partial-pitch shifts observed for harmonic and frequency-shifted stimuli suggests that they arise from a grouping mechanism that is sensitive to spectral regularity.

Partial regularity of viscosity solutions for a class of Kolmogorov equations arising from mathematical finance

NASA Astrophysics Data System (ADS)

Rosestolato, M.; Święch, A.

2017-02-01

We study value functions which are viscosity solutions of certain Kolmogorov equations. Using PDE techniques we prove that they are C 1 + α regular on special finite dimensional subspaces. The problem has origins in hedging derivatives of risky assets in mathematical finance.

Test Anxiety? Try a Stick of Gum...

ERIC Educational Resources Information Center

Wilmore, Elaine L.

American schools face pressure to increase their students' test scores. Research reports have shown American students to be particularly stressed over test taking partially because of other outside interests in their lives that also take up time. This paper offers tips to help students relieve stress arising from the testing situation. Students…

Church and Campus: Government Regulation of Religiously Affiliated Higher Education.

ERIC Educational Resources Information Center

Moots, Philip R.; Gaffney, Edward McGlynn, Jr.

A study on government regulation of religiously affiliated higher education was conducted for the Sloan Commission on Government and Higher Education. The following two questions were addressed: What legal problems arising from governmental regulation have religiously affiliated colleges experienced at least partially because of their religious…

48 CFR 49.112-1 - Partial payments.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., purchased parts, supplies, and direct labor; (4) 90 percent of other allowable costs (including settlement... terminated portion of the contract; and (2) The amounts of all credits arising from the purchase, retention... interest shall be computed at the rate established by the Secretary of the Treasury under 50 U.S.C. App...

Mean Field Type Control with Congestion

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

Achdou, Yves, E-mail: achdou@ljll.univ-paris-diderot.fr; Laurière, Mathieu

2016-06-15

We analyze some systems of partial differential equations arising in the theory of mean field type control with congestion effects. We look for weak solutions. Our main result is the existence and uniqueness of suitably defined weak solutions, which are characterized as the optima of two optimal control problems in duality.

The Tibetan singing bowl

NASA Astrophysics Data System (ADS)

Bush, John; Terwagne, Denis

2010-11-01

Tibetan singing bowls have been used for centuries for healing, meditation and shamanic journeying. The bowls are partially filled with water, then excited by either striking or rubbing the walls of the bowl with a mallet. A wealth of curious fluid mechanical phenomena arise, and will be elucidated in our combined experimental and theoretical investigation.

A molecular mechanism of adaptation in an estuarine copepod

NASA Astrophysics Data System (ADS)

Bradley, Brian P.; Lane, Maxine A.; Gonzalez, Carole M.

The estuarine copepod Eurytemora affinis (Poppe) has been shown to adapt better at the individual (physiological) and population (genetic) level to rapidly cycling environments than to slowly cycling temperatures. In addition, female copepods are physiologically more flexible than males. Three questions arise from these observations. Why is the geographical and seasonal distribution of Eurytemora in estuaries so limited? Why is the genetic variance so high in an organism which is so physiologically flexible? And does the difference between sexes help to explain the maintenance of genetic variance? A mechanism of adaptation which may allow further examination of these questions is the increased synthesis of stress proteins, first identified as heat shock proteins (HSP). The HSPs in the copepod Eurytemora affinis are quantitatively and qualitatively related to stress. Temperature and osmotic stress, for example, induce different sets of proteins. Thus, better understanding the phenomenon may be useful in marine ecology.

A Partial Least-Squares Analysis of Health-Related Quality-of-Life Outcomes After Aneurysmal Subarachnoid Hemorrhage.

PubMed

Young, Julia M; Morgan, Benjamin R; Mišić, Bratislav; Schweizer, Tom A; Ibrahim, George M; Macdonald, R Loch

2015-12-01

Individuals who have aneurysmal subarachnoid hemorrhages (SAHs) experience decreased health-related qualities of life (HRQoLs) that persist after the primary insult. To identify clinical variables that concurrently associate with HRQoL outcomes by using a partial least-squares approach, which has the distinct advantage of explaining multidimensional variance where predictor variables may be highly collinear. Data collected from the CONSCIOUS-1 trial was used to extract 29 clinical variables including SAH presentation, hospital procedures, and demographic information in addition to 5 HRQoL outcome variables for 256 individuals. A partial least-squares analysis was performed by calculating a heterogeneous correlation matrix and applying singular value decomposition to determine components that best represent the correlations between the 2 sets of variables. Bootstrapping was used to estimate statistical significance. The first 2 components accounting for 81.6% and 7.8% of the total variance revealed significant associations between clinical predictors and HRQoL outcomes. The first component identified associations between disability in self-care with longer durations of critical care stay, invasive intracranial monitoring, ventricular drain time, poorer clinical grade on presentation, greater amounts of cerebral spinal fluid drainage, and a history of hypertension. The second component identified associations between disability due to pain and discomfort as well as anxiety and depression with greater body mass index, abnormal heart rate, longer durations of deep sedation and critical care, and higher World Federation of Neurosurgical Societies and Hijdra scores. By applying a data-driven, multivariate approach, we identified robust associations between SAH clinical presentations and HRQoL outcomes. EQ-VAS, EuroQoL visual analog scaleHRQoL, health-related quality of lifeICU, intensive care unitIVH, intraventricular hemorrhagePLS, partial least squaresSAH, subarachnoid hemorrhageSVD, singular value decompositionWFNS, World Federation of Neurosurgical Societies.

Within-Subject Comparison of Changes in a Pretest-Posttest Design

ERIC Educational Resources Information Center

Hennig, Christian; Mullensiefen, Daniel; Bargmann, Jens

2010-01-01

The authors propose a method to compare the influence of a treatment on different properties within subjects. The properties are measured by several Likert-type-scaled items. The results show that many existing approaches, such as repeated measurement analysis of variance on sum and mean scores, a linear partial credit model, and a graded response…

Thermal regimes and snowpack relations of periglacial talus slopes, Sierra Nevada, California, USA.

Treesearch

Constance I Millar; Robert D. Westfall; Diane L. Delany

2014-01-01

Thermal regimes of eight periglacial talus slopes, at contrasting elevations, aspects, and substrates, in the Sierra Nevada, California, had complex microclimatic patterns partially decoupled from external conditions. Over three years, warm seasons showed mean talus matrix temperatures and daily variances lower than surfaces and cooler than free-air; talus surface and...

Distinguishing between direct and indirect directional couplings in large oscillator networks: Partial or non-partial phase analyses?

NASA Astrophysics Data System (ADS)

Rings, Thorsten; Lehnertz, Klaus

2016-09-01

We investigate the relative merit of phase-based methods for inferring directional couplings in complex networks of weakly interacting dynamical systems from multivariate time-series data. We compare the evolution map approach and its partialized extension to each other with respect to their ability to correctly infer the network topology in the presence of indirect directional couplings for various simulated experimental situations using coupled model systems. In addition, we investigate whether the partialized approach allows for additional or complementary indications of directional interactions in evolving epileptic brain networks using intracranial electroencephalographic recordings from an epilepsy patient. For such networks, both direct and indirect directional couplings can be expected, given the brain's connection structure and effects that may arise from limitations inherent to the recording technique. Our findings indicate that particularly in larger networks (number of nodes ≫10 ), the partialized approach does not provide information about directional couplings extending the information gained with the evolution map approach.

Weighted partial least squares based on the error and variance of the recovery rate in calibration set.

PubMed

Yu, Shaohui; Xiao, Xue; Ding, Hong; Xu, Ge; Li, Haixia; Liu, Jing

2017-08-05

The quantitative analysis is very difficult for the emission-excitation fluorescence spectroscopy of multi-component mixtures whose fluorescence peaks are serious overlapping. As an effective method for the quantitative analysis, partial least squares can extract the latent variables from both the independent variables and the dependent variables, so it can model for multiple correlations between variables. However, there are some factors that usually affect the prediction results of partial least squares, such as the noise, the distribution and amount of the samples in calibration set etc. This work focuses on the problems in the calibration set that are mentioned above. Firstly, the outliers in the calibration set are removed by leave-one-out cross-validation. Then, according to two different prediction requirements, the EWPLS method and the VWPLS method are proposed. The independent variables and dependent variables are weighted in the EWPLS method by the maximum error of the recovery rate and weighted in the VWPLS method by the maximum variance of the recovery rate. Three organic matters with serious overlapping excitation-emission fluorescence spectroscopy are selected for the experiments. The step adjustment parameter, the iteration number and the sample amount in the calibration set are discussed. The results show the EWPLS method and the VWPLS method are superior to the PLS method especially for the case of small samples in the calibration set. Copyright © 2017 Elsevier B.V. All rights reserved.

Familial influences on the full range of variability in attention and activity levels during adolescence: A longitudinal twin study.

PubMed

Peng, Chun-Zi; Grant, Julia D; Heath, Andrew C; Reiersen, Angela M; Mulligan, Richard C; Anokhin, Andrey P

2016-05-01

To investigate familial influences on the full range of variability in attention and activity across adolescence, we collected maternal ratings of 339 twin pairs at ages 12, 14, and 16, and estimated the transmitted and new familial influences on attention and activity as measured by the Strengths and Weaknesses of Attention-Deficit/Hyperactivity Disorder Symptoms and Normal Behavior Scale. Familial influences were substantial for both traits across adolescence: genetic influences accounted for 54%-73% (attention) and 31%-73% (activity) of the total variance, and shared environmental influences accounted for 0%-22% of the attention variance and 13%-57% of the activity variance. The longitudinal stability of individual differences in attention and activity was largely accounted for by familial influences transmitted from previous ages. Innovations over adolescence were also partially attributable to familial influences. Studying the full range of variability in attention and activity may facilitate our understanding of attention-deficit/hyperactivity disorder's etiology and intervention.

Diagnostic Models as Partially Ordered Sets

ERIC Educational Resources Information Center

Tatsuoka, Curtis

2009-01-01

In this commentary, the author addresses what is referred to as the deterministic input, noisy "and" gate (DINA) model. The author mentions concerns with how this model has been formulated and presented. In particular, the author points out that there is a lack of recognition of the confounding of profiles that generally arises and then discusses…

Surveying the Scene: Learning Metaphors, Survey Design and the Workplace Context

ERIC Educational Resources Information Center

Felstead, Alan; Fuller, Alison; Unwin, Lorna; Ashton, David; Butler, Peter; Lee, Tracey

2005-01-01

The skills debate in many European countries has for many years been preoccupied with the supply of qualified individuals and participation in training events. However, recent case-study work suggests that qualifications and training are partial measures of skill development as most learning arises naturally out of the demands and challenges of…

Evidence from Visuomotor Adaptation for Two Partially Independent Visuomotor Systems

ERIC Educational Resources Information Center

Thaler, Lore; Todd, James T.

2010-01-01

Visual information can specify spatial layout with respect to the observer (egocentric) or with respect to an external frame of reference (allocentric). People can use both of these types of visual spatial information to guide their hands. The question arises if movements based on egocentric and movements based on allocentric visual information…

External benefits of natural environments

Treesearch

Larry W. Tombaugh

1971-01-01

Existing methods of assessing economic benefits arising from certain physical environments left in a relatively natural condition do not include estimates of external benefits. Existence value is one such external benefit that accrues to individuals who have no intention of ever visiting the area in question. A partial measure of the existence value of National Parks...

Maintaining evolvability.

PubMed

Crow, James F

2008-12-01

Although molecular methods, such as QTL mapping, have revealed a number of loci with large effects, it is still likely that the bulk of quantitative variability is due to multiple factors, each with small effect. Typically, these have a large additive component. Conventional wisdom argues that selection, natural or artificial, uses up additive variance and thus depletes its supply. Over time, the variance should be reduced, and at equilibrium be near zero. This is especially expected for fitness and traits highly correlated with it. Yet, populations typically have a great deal of additive variance, and do not seem to run out of genetic variability even after many generations of directional selection. Long-term selection experiments show that populations continue to retain seemingly undiminished additive variance despite large changes in the mean value. I propose that there are several reasons for this. (i) The environment is continually changing so that what was formerly most fit no longer is. (ii) There is an input of genetic variance from mutation, and sometimes from migration. (iii) As intermediate-frequency alleles increase in frequency towards one, producing less variance (as p --> 1, p(1 - p) --> 0), others that were originally near zero become more common and increase the variance. Thus, a roughly constant variance is maintained. (iv) There is always selection for fitness and for characters closely related to it. To the extent that the trait is heritable, later generations inherit a disproportionate number of genes acting additively on the trait, thus increasing genetic variance. For these reasons a selected population retains its ability to evolve. Of course, genes with large effect are also important. Conspicuous examples are the small number of loci that changed teosinte to maize, and major phylogenetic changes in the animal kingdom. The relative importance of these along with duplications, chromosome rearrangements, horizontal transmission and polyploidy is yet to be determined. It is likely that only a case-by-case analysis will provide the answers. Despite the difficulties that complex interactions cause for evolution in Mendelian populations, such populations nevertheless evolve very well. Longlasting species must have evolved mechanisms for coping with such problems. Since such difficulties do not arise in asexual populations, a comparison of epistatic patterns in closely related sexual and asexual species might provide some important insights.

The Principal as a Key Actor in Promoting Teachers' Innovativeness--Analyzing the Innovativeness of Teaching Staff with Variance-Based Partial Least Square Modeling

ERIC Educational Resources Information Center

Buske, Ramona

2018-01-01

The study examines the correlation between collective innovativeness of the teaching staff and the principal's leadership style as well as additional school structure characteristics. The construct of collective innovativeness is examined as a precondition of successful school improvement processes driven by the teaching staff. Based on…

MULTIVARIATE ANALYSES (CONONICAL CORRELATION AND PARTIAL LEAST SQUARE, PLS) TO MODEL AND ASSESS THE ASSOCIATION OF LANDSCAPE METRICS TO SURFACE WATER CHEMICAL AND BIOLOGICAL PROPERTIES USING SAVANNAH RIVER BASIN DATA.

EPA Science Inventory

Many multivariate methods are used in describing and predicting relation; each has its unique usage of categorical and non-categorical data. In multivariate analysis of variance (MANOVA), many response variables (y's) are related to many independent variables that are categorical...

Genetic variation of the riparian pioneer tree species populus nigra. II. Variation In susceptibility to the foliar rust melampsora larici-populina

PubMed

Legionnet; Muranty; Lefevre

1999-04-01

Partial resistance of Populus nigra L. to three races of the foliar rust Melampsora larici-populina Kleb. was studied in a field trial and in laboratory tests, using a collection of P. nigra originating from different places throughout France. No total resistance was found. The partial resistance was split into epidemiological components, which proved to be under genetic control. Various patterns of association of epidemiological components values were found. Principal components analysis revealed their relationships. Only 24% of the variance of the field susceptibility could be explained by the variation of the epidemiological components of susceptibility. This variable was significantly correlated with susceptibility to the most ancient and widespread race of the pathogen, and with the variables related to the size of the lesions of the different races. Analysis of variance showed significant differences in susceptibility between regions and between stands within one region. Up to 20% of variation was between regions, and up to 22% between stands, so that these genetic factors appeared to be more differentiated than the neutral diversity (up to 3.5% Legionnet & Lefevre, 1996). However, no clear pattern of geographical distribution of diversity was detected.

Internalized Homophobia as a Partial Mediator between Homophobic Bullying and Self-Esteem among Sexual Minority Youths in Quebec (Canada)

PubMed Central

Blais, Martin; Gervais, Jesse; Hébert, Martine

2016-01-01

Verbal/psychological homophobic bullying is widespread among sexual minority youths. Homophobic bullying has been associated with both high internalized homophobia and low self-esteem. The objectives were to document verbal/psychological homophobic bullying among sexual minority youths and to model the relationships between homophobic bullying, internalized homophobia and self-esteem. Method: A community sample of 300 sexual minority youths aged 14 to 22 years old was used. A structural equations model was tested using a nonlinear, robust estimator implemented in Mplus. The model postulated that homophobic bullying impacts self-esteem both directly and indirectly, via internalized homophobia. Results: 60.7% of the sample reported at least on form of verbal/psychological homophobic bullying. The model explained 29% of the variance of self-esteem, 19.6% of the variance of internalized homophobia and 5.3% of the verbal/psychological homophobic bullying. The model suggests that the relationship between verbal/psychological homophobic bullying and self-esteem is partially mediated by internalized homophobia. Conclusion: Our results underscore the importance of initiatives to prevent homophobic bullying in order to prevent its negative effects on well-being of sexual minority youths. PMID:24714888

Effective Size of Nonrandom Mating Populations

PubMed Central

Caballero, A.; Hill, W. G.

1992-01-01

Nonrandom mating whereby parents are related is expected to cause a reduction in effective population size because their gene frequencies are correlated and this will increase the genetic drift. The published equation for the variance effective size, N(e), which includes the possibility of nonrandom mating, does not take into account such a correlation, however. Further, previous equations to predict effective sizes in populations with partial sib mating are shown to be different, but also incorrect. In this paper, a corrected form of these equations is derived and checked by stochastic simulation. For the case of stable census number, N, and equal progeny distributions for each sex, the equation is & where S(k)(2) is the variance of family size and α is the departure from Hardy-Weinberg proportions. For a Poisson distribution of family size (S(k)(2) = 2), it reduces to N(e) = N/(1 + α), as when inbreeding is due to selfing. When nonrandom mating occurs because there is a specified system of partial inbreeding every generation, α can be substituted by Wright's F(IS) statistic, to give the effective size as a function of the proportion of inbred mates. PMID:1582565

Internalized homophobia as a partial mediator between homophobic bullying and self-esteem among youths of sexual minorities in Quebec (Canada).

PubMed

Blais, Martin; Gervais, Jesse; Hébert, Martine

2014-03-01

Verbal/psychological homophobic bullying is widespread among youths of sexual minorities. Homophobic bullying has been associated with both high internalized homophobia and low self-esteem. The objectives were to document verbal/psychological homophobic bullying among youths of sexual minorities and model the relationships between homophobic bullying, internalized homophobia and self-esteem. A community sample of 300 youths of sexual minorities aged 14 to 22 years old was used. A structural equation model was tested using a nonlinear, robust estimator implemented in Mplus. The model postulated that homophobic bullying impacts self-esteem both directly and indirectly, via internalized homophobia. 60.7% of the sample reported at least one form of verbal/psychological homophobic bullying. The model explained 29% of the variance of self-esteem, 19.6% of the variance of internalized homophobia and 5.3% of the verbal/psychological homophobic bullying. The model suggests that the relationship between verbal/psychological homophobic bullying and self-esteem is partially mediated by internalized homophobia. The results underscore the importance of initiatives to prevent homophobic bullying in order to prevent its negative effects on the well-being of youths of sexual minorities.

Statistical State Dynamics Based Study of the Role of Nonlinearity in the Maintenance of Turbulence in Couette Flow

NASA Astrophysics Data System (ADS)

Farrell, Brian; Ioannou, Petros; Nikolaidis, Marios-Andreas

2017-11-01

While linear non-normality underlies the mechanism of energy transfer from the externally driven flow to the perturbation field, nonlinearity is also known to play an essential role in sustaining turbulence. We report a study based on the statistical state dynamics of Couette flow turbulence with the goal of better understanding the role of nonlinearity in sustaining turbulence. The statistical state dynamics implementations used are ensemble closures at second order in a cumulant expansion of the Navier-Stokes equations in which the averaging operator is the streamwise mean. Two fundamentally non-normal mechanisms potentially contributing to maintaining the second cumulant are identified. These are essentially parametric perturbation growth arising from interaction of the perturbations with the fluctuating mean flow and transient growth of perturbations arising from nonlinear interaction between components of the perturbation field. By the method of selectively including these mechanisms parametric growth is found to maintain the perturbation field in the turbulent state while the more commonly invoked mechanism associated with transient growth of perturbations arising from scattering by nonlinear interaction is found to suppress perturbation variance. Funded by ERC Coturb Madrid Summer Program and NSF AGS-1246929.

Ganglion cyst arising from the composite occipito-atlanto-axial joint cavity in a cat.

PubMed

Aikawa, T; Sadahiro, S; Nishimura, M; Miyazaki, Y; Shibata, M

2014-01-01

A four-year-old, female spayed Domestic Longhaired cat was referred for evaluation with a two month history of initial inability to jump progressing to ambulatory tetraparesis. Magnetic resonance imaging studies demonstrated a cystic lesion arising from the composite occipito-atlanto-axial joint cavity and extending to the region of the occipital bone and the axis. The lesion surrounded the spinal canal, causing moderate dorsal spinal cord compression at the atlanto-occipital joint. A dynamic myelographic study demonstrated attenuation of the dorsal contrast column at the atlanto-occipital joint when the cervical spine was positioned in extension. Partial excision of the cyst capsule by a ventral approach resulted in long-term (64 months) resolution of clinical signs. Histological evaluation was consistent with a ganglion cyst. An intra-spinal ganglion cyst arising from the composite occipito-atlanto-axial joint cavity may be considered as an uncommon differential diagnosis for cats with cervical myelopathy.

Polarimetry based partial least square classification of ex vivo healthy and basal cell carcinoma human skin tissues.

PubMed

Ahmad, Iftikhar; Ahmad, Manzoor; Khan, Karim; Ikram, Masroor

2016-06-01

Optical polarimetry was employed for assessment of ex vivo healthy and basal cell carcinoma (BCC) tissue samples from human skin. Polarimetric analyses revealed that depolarization and retardance for healthy tissue group were significantly higher (p<0.001) compared to BCC tissue group. Histopathology indicated that these differences partially arise from BCC-related characteristic changes in tissue morphology. Wilks lambda statistics demonstrated the potential of all investigated polarimetric properties for computer assisted classification of the two tissue groups. Based on differences in polarimetric properties, partial least square (PLS) regression classified the samples with 100% accuracy, sensitivity and specificity. These findings indicate that optical polarimetry together with PLS statistics hold promise for automated pathology classification. Copyright © 2016 Elsevier B.V. All rights reserved.

Ethical issues in nanomedicine: Tempest in a teapot?

PubMed

Allon, Irit; Ben-Yehudah, Ahmi; Dekel, Raz; Solbakk, Jan-Helge; Weltring, Klaus-Michael; Siegal, Gil

2017-03-01

Nanomedicine offers remarkable options for new therapeutic avenues. As methods in nanomedicine advance, ethical questions conjunctly arise. Nanomedicine is an exceptional niche in several aspects as it reflects risks and uncertainties not encountered in other areas of medical research or practice. Nanomedicine partially overlaps, partially interlocks and partially exceeds other medical disciplines. Some interpreters agree that advances in nanotechnology may pose varied ethical challenges, whilst others argue that these challenges are not new and that nanotechnology basically echoes recurrent bioethical dilemmas. The purpose of this article is to discuss some of the ethical issues related to nanomedicine and to reflect on the question whether nanomedicine generates ethical challenges of new and unique nature. Such a determination should have implications on regulatory processes and professional conducts and protocols in the future.

Central Auditory Processing of Temporal and Spectral-Variance Cues in Cochlear Implant Listeners

PubMed Central

Pham, Carol Q.; Bremen, Peter; Shen, Weidong; Yang, Shi-Ming; Middlebrooks, John C.; Zeng, Fan-Gang; Mc Laughlin, Myles

2015-01-01

Cochlear implant (CI) listeners have difficulty understanding speech in complex listening environments. This deficit is thought to be largely due to peripheral encoding problems arising from current spread, which results in wide peripheral filters. In normal hearing (NH) listeners, central processing contributes to segregation of speech from competing sounds. We tested the hypothesis that basic central processing abilities are retained in post-lingually deaf CI listeners, but processing is hampered by degraded input from the periphery. In eight CI listeners, we measured auditory nerve compound action potentials to characterize peripheral filters. Then, we measured psychophysical detection thresholds in the presence of multi-electrode maskers placed either inside (peripheral masking) or outside (central masking) the peripheral filter. This was intended to distinguish peripheral from central contributions to signal detection. Introduction of temporal asynchrony between the signal and masker improved signal detection in both peripheral and central masking conditions for all CI listeners. Randomly varying components of the masker created spectral-variance cues, which seemed to benefit only two out of eight CI listeners. Contrastingly, the spectral-variance cues improved signal detection in all five NH listeners who listened to our CI simulation. Together these results indicate that widened peripheral filters significantly hamper central processing of spectral-variance cues but not of temporal cues in post-lingually deaf CI listeners. As indicated by two CI listeners in our study, however, post-lingually deaf CI listeners may retain some central processing abilities similar to NH listeners. PMID:26176553

Correlational structure of ‘frontal’ tests and intelligence tests indicates two components with asymmetrical neurostructural correlates in old age

PubMed Central

Cox, Simon R.; MacPherson, Sarah E.; Ferguson, Karen J.; Nissan, Jack; Royle, Natalie A.; MacLullich, Alasdair M.J.; Wardlaw, Joanna M.; Deary, Ian J.

2014-01-01

Both general fluid intelligence (gf) and performance on some ‘frontal tests’ of cognition decline with age. Both types of ability are at least partially dependent on the integrity of the frontal lobes, which also deteriorate with age. Overlap between these two methods of assessing complex cognition in older age remains unclear. Such overlap could be investigated using inter-test correlations alone, as in previous studies, but this would be enhanced by ascertaining whether frontal test performance and gf share neurobiological variance. To this end, we examined relationships between gf and 6 frontal tests (Tower, Self-Ordered Pointing, Simon, Moral Dilemmas, Reversal Learning and Faux Pas tests) in 90 healthy males, aged ~ 73 years. We interpreted their correlational structure using principal component analysis, and in relation to MRI-derived regional frontal lobe volumes (relative to maximal healthy brain size). gf correlated significantly and positively (.24 ≤ r ≤ .53) with the majority of frontal test scores. Some frontal test scores also exhibited shared variance after controlling for gf. Principal component analysis of test scores identified units of gf-common and gf-independent variance. The former was associated with variance in the left dorsolateral (DL) and anterior cingulate (AC) regions, and the latter with variance in the right DL and AC regions. Thus, we identify two biologically-meaningful components of variance in complex cognitive performance in older age and suggest that age-related changes to DL and AC have the greatest cognitive impact. PMID:25278641

Correlational structure of 'frontal' tests and intelligence tests indicates two components with asymmetrical neurostructural correlates in old age.

PubMed

Cox, Simon R; MacPherson, Sarah E; Ferguson, Karen J; Nissan, Jack; Royle, Natalie A; MacLullich, Alasdair M J; Wardlaw, Joanna M; Deary, Ian J

2014-09-01

Both general fluid intelligence ( g f ) and performance on some 'frontal tests' of cognition decline with age. Both types of ability are at least partially dependent on the integrity of the frontal lobes, which also deteriorate with age. Overlap between these two methods of assessing complex cognition in older age remains unclear. Such overlap could be investigated using inter-test correlations alone, as in previous studies, but this would be enhanced by ascertaining whether frontal test performance and g f share neurobiological variance. To this end, we examined relationships between g f and 6 frontal tests (Tower, Self-Ordered Pointing, Simon, Moral Dilemmas, Reversal Learning and Faux Pas tests) in 90 healthy males, aged ~ 73 years. We interpreted their correlational structure using principal component analysis, and in relation to MRI-derived regional frontal lobe volumes (relative to maximal healthy brain size). g f correlated significantly and positively (.24 ≤  r  ≤ .53) with the majority of frontal test scores. Some frontal test scores also exhibited shared variance after controlling for g f . Principal component analysis of test scores identified units of g f -common and g f -independent variance. The former was associated with variance in the left dorsolateral (DL) and anterior cingulate (AC) regions, and the latter with variance in the right DL and AC regions. Thus, we identify two biologically-meaningful components of variance in complex cognitive performance in older age and suggest that age-related changes to DL and AC have the greatest cognitive impact.

Theoretical Prediction of Magnetism in C-doped TlBr

NASA Astrophysics Data System (ADS)

Zhou, Yuzhi; Haller, E. E.; Chrzan, D. C.

2014-05-01

We predict that C, N, and O dopants in TlBr can display large, localized magnetic moments. Density functional theory based electronic structure calculations show that the moments arise from partial filling of the crystal-field-split localized p states of the dopant atoms. A simple model is introduced to explain the magnitude of the moments.

A Probabilistic-Numerical Approximation for an Obstacle Problem Arising in Game Theory

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

Gruen, Christine, E-mail: christine.gruen@univ-brest.fr

We investigate a two-player zero-sum stochastic differential game in which one of the players has more information on the game than his opponent. We show how to construct numerical schemes for the value function of this game, which is given by the solution of a quasilinear partial differential equation with obstacle.

An evolution infinity Laplace equation modelling dynamic elasto-plastic torsion

NASA Astrophysics Data System (ADS)

Messelmi, Farid

2017-12-01

We consider in this paper a parabolic partial differential equation involving the infinity Laplace operator and a Leray-Lions operator with no coercitive assumption. We prove the existence and uniqueness of the corresponding approached problem and we show that at the limit the solution solves the parabolic variational inequality arising in the elasto-plastic torsion problem.

Odor-Specific Habituation Arises from Interaction of Afferent Synaptic Adaptation and Intrinsic Synaptic Potentiation in Olfactory Cortex

ERIC Educational Resources Information Center

Linster, Christiane; Menon, Alka V.; Singh, Christopher Y.; Wilson, Donald A.

2009-01-01

Segmentation of target odorants from background odorants is a fundamental computational requirement for the olfactory system and is thought to be behaviorally mediated by olfactory habituation memory. Data from our laboratory have shown that odor-specific adaptation in piriform neurons, mediated at least partially by synaptic adaptation between…

Computational Algorithms or Identification of Distributed Parameter Systems

DTIC Science & Technology

1993-04-24

delay-differential equations, Volterra integral equations, and partial differential equations with memory terms . In particular we investigated a...tested for estimating parameters in a Volterra integral equation arising from a viscoelastic model of a flexible structure with Boltzmann damping. In...particular, one of the parameters identified was the order of the derivative in Volterra integro-differential equations containing fractional

Generalized symmetries and [ital w][sub [infinity

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

Lou, S.

After establishing a formal theory for getting solutions of one type of high-dimensional partial differential equation, two sets of generalized symmetries of the 3D Toda theory, which arises from a particular reduction of the 4D self-dual gravity equation, are obtained concretely by a simple formula. Each set of symmetries constitutes a generalized [omega][sub [infinity

Characterization of near infrared spectral variance in the authentication of skim and nonfat dry milk powder collection using ANOVA-PCA, Pooled-ANOVA, and partial least squares regression

USDA-ARS?s Scientific Manuscript database

Forty-one samples of skim milk powder (SMP) and non-fat dry milk (NFDM) from 8 suppliers, 13 production sites, and 3 processing temperatures were analyzed by NIR diffuse reflectance spectrometry over a period of three days. NIR reflectance spectra (1700-2500 nm) were converted to pseudo-absorbance ...

The role of executive functioning in memory performance in pediatric focal epilepsy.

PubMed

Sepeta, Leigh N; Casaletto, Kaitlin Blackstone; Terwilliger, Virginia; Facella-Ervolini, Joy; Sady, Maegan; Mayo, Jessica; Gaillard, William D; Berl, Madison M

2017-02-01

Learning and memory are essential for academic success and everyday functioning, but the pattern of memory skills and its relationship to executive functioning in children with focal epilepsy is not fully delineated. We address a gap in the literature by examining the relationship between memory and executive functioning in a pediatric focal epilepsy population. Seventy children with focal epilepsy and 70 typically developing children matched on age, intellectual functioning, and gender underwent neuropsychological assessment, including measures of intelligence (Wechsler Abbreviated Scale of Intelligence [WASI]/Differential Ability Scales [DAS]), as well as visual Children's Memory Scale (CMS Dot Locations) and verbal episodic memory (Wide Range Assessment of Memory and Learning [WRAML] Story Memory and California Verbal Learning Test for Children [CVLT-C]). Executive functioning was measured directly (WISC-IV Digit Span Backward; Clinical Evaluation of Language Fundamentals, Fourth Edition (CELF-IV) Recalling Sentences) and by parent report (Behavior Rating Inventory of Executive Function [BRIEF]). Children with focal epilepsy had lower delayed free-recall scores than controls across visual and verbal memory tasks (p = 0.02; partial η 2 = 0.12). In contrast, recognition memory performance was similar for patients and controls (p = 0.36; partial η 2 = 0.03). Children with focal epilepsy demonstrated difficulties in working memory (p = 0.02; partial η 2 = 0.08) and planning/organization (p = 0.02) compared to controls. Working memory predicted 9-19% of the variance in delayed free recall for verbal and visual memory; organization predicted 9-10% of the variance in verbal memory. Patients with both left and right focal epilepsy demonstrated more difficulty on verbal versus visual tasks (p = 0.002). Memory performance did not differ by location of seizure foci (temporal vs. extratemporal, frontal vs. extrafrontal). Children with focal epilepsy demonstrated memory ability within age-level expectations, but delayed free recall was inefficient compared to typically developing controls. Memory difficulties were not related to general cognitive impairment or seizure localization. Executive functioning accounted for significant variance in memory performance, suggesting that poor executive control negatively influences memory retrieval. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

Mechanism of cAMP Partial Agonism in Protein Kinase G (PKG)*♦

PubMed Central

VanSchouwen, Bryan; Selvaratnam, Rajeevan; Giri, Rajanish; Lorenz, Robin; Herberg, Friedrich W.; Kim, Choel; Melacini, Giuseppe

2015-01-01

Protein kinase G (PKG) is a major receptor of cGMP and controls signaling pathways often distinct from those regulated by cAMP. Hence, the selective activation of PKG by cGMP versus cAMP is critical. However, the mechanism of cGMP-versus-cAMP selectivity is only limitedly understood. Although the C-terminal cyclic nucleotide-binding domain B of PKG binds cGMP with higher affinity than cAMP, the intracellular concentrations of cAMP are typically higher than those of cGMP, suggesting that the cGMP-versus-cAMP selectivity of PKG is not controlled uniquely through affinities. Here, we show that cAMP is a partial agonist for PKG, and we elucidate the mechanism for cAMP partial agonism through the comparative NMR analysis of the apo, cGMP-, and cAMP-bound forms of the PKG cyclic nucleotide-binding domain B. We show that although cGMP activation is adequately explained by a two-state conformational selection model, the partial agonism of cAMP arises from the sampling of a third, partially autoinhibited state. PMID:26370085

Measurement invariance versus selection invariance: is fair selection possible?

PubMed

Borsboom, Denny; Romeijn, Jan-Willem; Wicherts, Jelte M

2008-06-01

This article shows that measurement invariance (defined in terms of an invariant measurement model in different groups) is generally inconsistent with selection invariance (defined in terms of equal sensitivity and specificity across groups). In particular, when a unidimensional measurement instrument is used and group differences are present in the location but not in the variance of the latent distribution, sensitivity and positive predictive value will be higher in the group at the higher end of the latent dimension, whereas specificity and negative predictive value will be higher in the group at the lower end of the latent dimension. When latent variances are unequal, the differences in these quantities depend on the size of group differences in variances relative to the size of group differences in means. The effect originates as a special case of Simpson's paradox, which arises because the observed score distribution is collapsed into an accept-reject dichotomy. Simulations show the effect can be substantial in realistic situations. It is suggested that the effect may be partly responsible for overprediction in minority groups as typically found in empirical studies on differential academic performance. A methodological solution to the problem is suggested, and social policy implications are discussed. (PsycINFO Database Record (c) 2008 APA, all rights reserved).

Spatial and visuospatial working memory tests predict performance in classic multiple-object tracking in young adults, but nonspatial measures of the executive do not.

PubMed

Trick, Lana M; Mutreja, Rachna; Hunt, Kelly

2012-02-01

An individual-differences approach was used to investigate the roles of visuospatial working memory and the executive in multiple-object tracking. The Corsi Blocks and Visual Patterns Tests were used to assess visuospatial working memory. Two relatively nonspatial measures of the executive were used: operation span (OSPAN) and reading span (RSPAN). For purposes of comparison, the digit span test was also included (a measure not expected to correlate with tracking). The tests predicted substantial amounts of variance (R (2) = .33), and the visuospatial measures accounted for the majority (R (2) = .30), with each making a significant contribution. Although the executive measures correlated with each other, the RSPAN did not correlate with tracking. The correlation between OSPAN and tracking was similar in magnitude to that between digit span and tracking (p < .05 for both), and when regression was used to partial out shared variance between the two tests, the remaining variance predicted by the OSPAN was minimal (sr ( 2 ) = .029). When measures of spatial memory were included in the regression, the unique variance predicted by the OSPAN became negligible (sr ( 2 ) = .000004). This suggests that the executive, as measured by tests such as the OSPAN, plays little role in explaining individual differences in multiple-object tracking.

Estimation and Simulation of Slow Crack Growth Parameters from Constant Stress Rate Data

NASA Technical Reports Server (NTRS)

Salem, Jonathan A.; Weaver, Aaron S.

2003-01-01

Closed form, approximate functions for estimating the variances and degrees-of-freedom associated with the slow crack growth parameters n, D, B, and A(sup *) as measured using constant stress rate ('dynamic fatigue') testing were derived by using propagation of errors. Estimates made with the resulting functions and slow crack growth data for a sapphire window were compared to the results of Monte Carlo simulations. The functions for estimation of the variances of the parameters were derived both with and without logarithmic transformation of the initial slow crack growth equations. The transformation was performed to make the functions both more linear and more normal. Comparison of the Monte Carlo results and the closed form expressions derived with propagation of errors indicated that linearization is not required for good estimates of the variances of parameters n and D by the propagation of errors method. However, good estimates variances of the parameters B and A(sup *) could only be made when the starting slow crack growth equation was transformed and the coefficients of variation of the input parameters were not too large. This was partially a result of the skewered distributions of B and A(sup *). Parametric variation of the input parameters was used to determine an acceptable range for using closed form approximate equations derived from propagation of errors.

Improved classification accuracy in 1- and 2-dimensional NMR metabolomics data using the variance stabilising generalised logarithm transformation

PubMed Central

Parsons, Helen M; Ludwig, Christian; Günther, Ulrich L; Viant, Mark R

2007-01-01

Background Classifying nuclear magnetic resonance (NMR) spectra is a crucial step in many metabolomics experiments. Since several multivariate classification techniques depend upon the variance of the data, it is important to first minimise any contribution from unwanted technical variance arising from sample preparation and analytical measurements, and thereby maximise any contribution from wanted biological variance between different classes. The generalised logarithm (glog) transform was developed to stabilise the variance in DNA microarray datasets, but has rarely been applied to metabolomics data. In particular, it has not been rigorously evaluated against other scaling techniques used in metabolomics, nor tested on all forms of NMR spectra including 1-dimensional (1D) 1H, projections of 2D 1H, 1H J-resolved (pJRES), and intact 2D J-resolved (JRES). Results Here, the effects of the glog transform are compared against two commonly used variance stabilising techniques, autoscaling and Pareto scaling, as well as unscaled data. The four methods are evaluated in terms of the effects on the variance of NMR metabolomics data and on the classification accuracy following multivariate analysis, the latter achieved using principal component analysis followed by linear discriminant analysis. For two of three datasets analysed, classification accuracies were highest following glog transformation: 100% accuracy for discriminating 1D NMR spectra of hypoxic and normoxic invertebrate muscle, and 100% accuracy for discriminating 2D JRES spectra of fish livers sampled from two rivers. For the third dataset, pJRES spectra of urine from two breeds of dog, the glog transform and autoscaling achieved equal highest accuracies. Additionally we extended the glog algorithm to effectively suppress noise, which proved critical for the analysis of 2D JRES spectra. Conclusion We have demonstrated that the glog and extended glog transforms stabilise the technical variance in NMR metabolomics datasets. This significantly improves the discrimination between sample classes and has resulted in higher classification accuracies compared to unscaled, autoscaled or Pareto scaled data. Additionally we have confirmed the broad applicability of the glog approach using three disparate datasets from different biological samples using 1D NMR spectra, 1D projections of 2D JRES spectra, and intact 2D JRES spectra. PMID:17605789

Estimating varying coefficients for partial differential equation models.

PubMed

Zhang, Xinyu; Cao, Jiguo; Carroll, Raymond J

2017-09-01

Partial differential equations (PDEs) are used to model complex dynamical systems in multiple dimensions, and their parameters often have important scientific interpretations. In some applications, PDE parameters are not constant but can change depending on the values of covariates, a feature that we call varying coefficients. We propose a parameter cascading method to estimate varying coefficients in PDE models from noisy data. Our estimates of the varying coefficients are shown to be consistent and asymptotically normally distributed. The performance of our method is evaluated by a simulation study and by an empirical study estimating three varying coefficients in a PDE model arising from LIDAR data. © 2017, The International Biometric Society.

An Elementary Introduction to Recently Developed Computational Methods for Solving Singularly Perturbed Partial Differential Equations Arising in Science and Engineering

NASA Astrophysics Data System (ADS)

Kumar, Manoj; Srivastava, Akanksha

2013-01-01

This paper presents a survey of innovative approaches of the most effective computational techniques for solving singular perturbed partial differential equations, which are useful because of their numerical and computer realizations. Many applied problems appearing in semiconductors theory, biochemistry, kinetics, theory of electrical chains, economics, solid mechanics, fluid dynamics, quantum mechanics, and many others can be modelled as singularly perturbed systems. Here, we summarize a wide range of research articles published by numerous researchers during the last ten years to get a better view of the present scenario in this area of research.

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

Lingam, Manasvi; Abdelhamid, Hamdi M.; Hudson, Stuart R.

The recent formulations of multi-region relaxed magnetohydrodynamics (MRxMHD) have generalized the famous Woltjer-Taylor states by incorporating a collection of “ideal barriers” that prevent global relaxation and flow. In this paper, we generalize MRxMHD with flow to include Hall effects, and thereby obtain the partially relaxed counterparts of the famous double Beltrami states as a special subset. The physical and mathematical consequences arising from the introduction of the Hall term are also presented. We demonstrate that our results (in the ideal MHD limit) constitute an important subset of ideal MHD equilibria, and we compare our approach against other variational principles proposedmore » for deriving the partially relaxed states.« less

On the Use of Ocean Dynamic Temperature for Hurricane Intensity Forecasting

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

Balaguru, Karthik; Foltz, Gregory R.; Leung, L. Ruby

Sea surface temperature (SST) and the Tropical Cyclone Heat Potential (TCHP) are metrics used to incorporate the ocean's influence on hurricane intensification in the National Hurricane Center's Statistical Hurricane Intensity Prediction Scheme (SHIPS). While both SST and TCHP serve as useful measures of the upper-ocean heat content, they do not accurately represent ocean stratification effects. Here we show that replacing SST in the SHIPS framework with a dynamic temperature (Tdy), which accounts for the oceanic negative feedback to the hurricane's intensity arising from storm-induced vertical mixing and sea-surface cooling, improves the model performance. While the model with SST and TCHPmore » explains nearly 41% of the variance in 36-hr intensity changes, replacing SST with Tdy increases the variance explained to nearly 44%. Our results suggest that representation of the oceanic feedback, even through relatively simple formulations such as Tdy, may improve the performance of statistical hurricane intensity prediction models such as SHIPS.« less

Large contribution of natural aerosols to uncertainty in indirect forcing

NASA Astrophysics Data System (ADS)

Carslaw, K. S.; Lee, L. A.; Reddington, C. L.; Pringle, K. J.; Rap, A.; Forster, P. M.; Mann, G. W.; Spracklen, D. V.; Woodhouse, M. T.; Regayre, L. A.; Pierce, J. R.

2013-11-01

The effect of anthropogenic aerosols on cloud droplet concentrations and radiative properties is the source of one of the largest uncertainties in the radiative forcing of climate over the industrial period. This uncertainty affects our ability to estimate how sensitive the climate is to greenhouse gas emissions. Here we perform a sensitivity analysis on a global model to quantify the uncertainty in cloud radiative forcing over the industrial period caused by uncertainties in aerosol emissions and processes. Our results show that 45 per cent of the variance of aerosol forcing since about 1750 arises from uncertainties in natural emissions of volcanic sulphur dioxide, marine dimethylsulphide, biogenic volatile organic carbon, biomass burning and sea spray. Only 34 per cent of the variance is associated with anthropogenic emissions. The results point to the importance of understanding pristine pre-industrial-like environments, with natural aerosols only, and suggest that improved measurements and evaluation of simulated aerosols in polluted present-day conditions will not necessarily result in commensurate reductions in the uncertainty of forcing estimates.

Optimal Solar PV Arrays Integration for Distributed Generation

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

Omitaomu, Olufemi A; Li, Xueping

2012-01-01

Solar photovoltaic (PV) systems hold great potential for distributed energy generation by installing PV panels on rooftops of residential and commercial buildings. Yet challenges arise along with the variability and non-dispatchability of the PV systems that affect the stability of the grid and the economics of the PV system. This paper investigates the integration of PV arrays for distributed generation applications by identifying a combination of buildings that will maximize solar energy output and minimize system variability. Particularly, we propose mean-variance optimization models to choose suitable rooftops for PV integration based on Markowitz mean-variance portfolio selection model. We further introducemore » quantity and cardinality constraints to result in a mixed integer quadratic programming problem. Case studies based on real data are presented. An efficient frontier is obtained for sample data that allows decision makers to choose a desired solar energy generation level with a comfortable variability tolerance level. Sensitivity analysis is conducted to show the tradeoffs between solar PV energy generation potential and variability.« less

Effects of Impression Material, Impression Tray Type, and Type of Partial Edentulism on the Fit of Cobalt-Chromium Partial Denture Frameworks on Initial Clinical Insertion: A Retrospective Clinical Evaluation.

PubMed

Baig, Mirza Rustum; Akbar, Jaber Hussain; Qudeimat, Muawia; Omar, Ridwaan

2018-02-15

To evaluate the effects of impression material, impression tray type, and type of partial edentulism (ie, Kennedy class) on the accuracy of fit of cobalt-chromium (Co-Cr) partial removable dental prostheses (PRDP) in terms of the number of fabricated frameworks required until the attainment of adequate fit. Electronic case documentations of 120 partially edentulous patients provided with Co-Cr PRDP treatment for one or both arches were examined. Statistical analyses of data were performed using analysis of variance and Tukey honest significant difference test to compare the relationships between the different factors and the number of frameworks that needed to be fabricated for each patient (α = .05). Statistical analysis of data derived from 143 records (69 maxillary and 74 mandibular) revealed no significant correlation between impression material, tray type, or Kennedy class and the number of construction attempts for the pooled or individual arch data (P ≥ .05). In PRDP treatment, alginate can be chosen as a first-choice material, and metal stock trays can be a preferred option for making final impressions to fabricate Co-Cr frameworks.

Partiality, impartiality and the ethics of triage.

PubMed

Okorie, Ndukaku

2018-06-22

In this paper, I discuss the question of partiality and impartiality in the application of triage. Triage is a process in medical research which recommends that patients should be sorted for treatment according to the degree or severity of their injury. In employing the triage protocol, however, the question of partiality arises because socially vulnerable groups will be neglected since there is the likelihood that the social determinants of a patient's health may diminish her chance of survival. As a process that is based on the severity of a patient's injury, triage will be unfair, and hence negatively partial, to socially vulnerable people. Thus, I aim in this paper to show that the triage protocol fails as an impartial evaluative process because its only aim is to maximize survivability. I contend that: (i) triage would lead to the neglect of the social condition of patients or victims, and (ii) it will only serve the utilitarian purpose of maximization of outcomes which may not be justified in some cases. © 2018 John Wiley & Sons Ltd.

Nasal airway and septal variation in unilateral and bilateral cleft lip and palate.

PubMed

Starbuck, John M; Friel, Michael T; Ghoneima, Ahmed; Flores, Roberto L; Tholpady, Sunil; Kula, Katherine

2014-10-01

Cleft lip and palate (CLP) affects the dentoalveolar and nasolabial facial regions. Internal and external nasal dysmorphology may persist in individuals born with CLP despite surgical interventions. 7-18 year old individuals born with unilateral and bilateral CLP (n = 50) were retrospectively assessed using cone beam computed tomography. Anterior, middle, and posterior nasal airway volumes were measured on each facial side. Septal deviation was measured at the anterior and posterior nasal spine, and the midpoint between these two locations. Data were evaluated using principal components analysis (PCA), multivariate analysis of variance (MANOVA), and post-hoc ANOVA tests. PCA results show partial separation in high dimensional space along PC1 (48.5% variance) based on age groups and partial separation along PC2 (29.8% variance) based on CLP type and septal deviation patterns. MANOVA results indicate that age (P = 0.007) and CLP type (P ≤ 0.001) significantly affect nasal airway volume and septal deviation. ANOVA results indicate that anterior nasal volume is significantly affected by age (P ≤ 0.001), whereas septal deviation patterns are significantly affected by CLP type (P ≤ 0.001). Age and CLP type affect nasal airway volume and septal deviation patterns. Nasal airway volumes tend to be reduced on the clefted sides of the face relative to non-clefted sides of the face. Nasal airway volumes tend to strongly increase with age, whereas septal deviation values tend to increase only slightly with age. These results suggest that functional nasal breathing may be impaired in individuals born with the unilateral and bilateral CLP deformity. © 2014 Wiley Periodicals, Inc.

Toddler Emotional States, Temperamental Traits, and Their Interaction: Associations with Mothers’ and Fathers’ Parenting

PubMed Central

Fields, Margaret A.; Cole, Pamela M.; Maggi, Mirella C.

2016-01-01

We investigated the degree to which toddlers’ observed emotional states, toddlers’ temperamental traits, and their interaction accounted for variance in mothers’ and fathers’ parenting. Main effects of two emotional states (positive emotion and negative emotion), three temperamental traits (negative affectivity, effortful control, and surgency) as well as state-by-trait interactions, were examined in relation to parental sensitivity, positive affect, and negative affect. The hypothesis that toddlers’ temperamental traits would moderate the association between their observed emotional states and parenting was partially supported. Significant state-by-trait interactions were found in models predicting the probability that mothers and fathers expressed negative affect towards their toddlers. For parental sensitivity and positive affect, only main effects of temperament and/or emotion expression accounted for variance in parenting. PMID:28479643

Characterizing partial AZFc deletions of the Y chromosome with amplicon-specific sequence markers

PubMed Central

Navarro-Costa, Paulo; Pereira, Luísa; Alves, Cíntia; Gusmão, Leonor; Proença, Carmen; Marques-Vidal, Pedro; Rocha, Tiago; Correia, Sónia C; Jorge, Sónia; Neves, António; Soares, Ana P; Nunes, Joaquim; Calhaz-Jorge, Carlos; Amorim, António; Plancha, Carlos E; Gonçalves, João

2007-01-01

Background The AZFc region of the human Y chromosome is a highly recombinogenic locus containing multi-copy male fertility genes located in repeated DNA blocks (amplicons). These AZFc gene families exhibit slight sequence variations between copies which are considered to have functional relevance. Yet, partial AZFc deletions yield phenotypes ranging from normospermia to azoospermia, thwarting definite conclusions on their real impact on fertility. Results The amplicon content of partial AZFc deletion products was characterized with novel amplicon-specific sequence markers. Data indicate that partial AZFc deletions are a male infertility risk [odds ratio: 5.6 (95% CI: 1.6–30.1)] and although high diversity of partial deletion products and sequence conversion profiles were recorded, the AZFc marker profiles detected in fertile men were also observed in infertile men. Additionally, the assessment of rearrangement recurrence by Y-lineage analysis indicated that while partial AZFc deletions occurred in highly diverse samples, haplotype diversity was minimal in fertile men sharing identical marker profiles. Conclusion Although partial AZFc deletion products are highly heterogeneous in terms of amplicon content, this plasticity is not sufficient to account for the observed phenotypical variance. The lack of causative association between the deletion of specific gene copies and infertility suggests that AZFc gene content might be part of a multifactorial network, with Y-lineage evolution emerging as a possible phenotype modulator. PMID:17903263

Recovering Wood and McCarthy's ERP-prototypes by means of ERP-specific procrustes-rotation.

PubMed

Beauducel, André

2018-02-01

The misallocation of treatment-variance on the wrong component has been discussed in the context of temporal principal component analysis of event-related potentials. There is, until now, no rotation-method that can perfectly recover Wood and McCarthy's prototypes without making use of additional information on treatment-effects. In order to close this gap, two new methods: for component rotation were proposed. After Varimax-prerotation, the first method identifies very small slopes of successive loadings. The corresponding loadings are set to zero in a target-matrix for event-related orthogonal partial Procrustes- (EPP-) rotation. The second method generates Gaussian normal distributions around the peaks of the Varimax-loadings and performs orthogonal Procrustes-rotation towards these Gaussian distributions. Oblique versions of this Gaussian event-related Procrustes- (GEP) rotation and of EPP-rotation are based on Promax-rotation. A simulation study revealed that the new orthogonal rotations recover Wood and McCarthy's prototypes and eliminate misallocation of treatment-variance. In an additional simulation study with a more pronounced overlap of the prototypes GEP Promax-rotation reduced the variance misallocation slightly more than EPP Promax-rotation. Comparison with Existing Method(s): Varimax- and conventional Promax-rotations resulted in substantial misallocations of variance in simulation studies when components had temporal overlap. A substantially reduced misallocation of variance occurred with the EPP-, EPP Promax-, GEP-, and GEP Promax-rotations. Misallocation of variance can be minimized by means of the new rotation methods: Making use of information on the temporal order of the loadings may allow for improvements of the rotation of temporal PCA components. Copyright © 2017 Elsevier B.V. All rights reserved.

Baseline Severity as Predictor of Change in St George’s Respiratory Questionnaire Scores in Trials of Long-acting Bronchodilators with COPD Patients

PubMed Central

Jones, Paul W.; Gelhorn, Heather; Karlsson, Niklas; Menjoge, Shailendra; Müllerova, Hana; Rennard, Stephen I.; Tal-Singer, Ruth; Wilson, Hilary; Merrill, Debora; Tabberer, Maggie

2017-01-01

Background: In trials oflong-acting bronchodilators, health status is an important trial outcome, however the influence of baseline severity on response measured by St George’s Respiratory Questionnaire (SGRQ) is not known. We have compared SGRQ changes between patients with chronic obstructive pulmonary disease (COPD) of mild-moderate severity or dyspnea (Global initiative for chronic Obstructive Lung disease [GOLD] grades 1 and 2; modified Medical Research Council [mMRC] grades 1 and 2) to those with severe-very severe severity or dyspnea (GOLD grades 3 and 4; mMRC grades 3 and 4). Methods: Combined individual patient data from the COPD Biomarkers Qualification Consortium database (trials of long-acting bronchodilators) were used comprising of patients from short-term (≤1-year duration; n=10802) and medium-term (2-4 years’ duration; n=8963) studies. A repeated measures analysis of variance (ANOVA) was used to determine the effects of baseline severity (GOLD/mMRC) on SGRQ response to treatment. All treatment arms were combined. Results: In short-term studies, milder patients showed a greater response than those with more severe disease in terms of GOLD grade (partial Eta2 = 0.03, p < 0.0001) and mMRC grade (partial Eta2 = 0.05, p < 0.0001). Similar results were seen in the medium-term studies (partial Eta2 = 0.02, p < 0.0001; mMRC: partial Eta2 = 0.05, p < 0.0001,). Conclusions: Patients with less severe airflow limitation and less severe dyspnea showed larger improvements in SGRQ score than more severely obstructed or dyspneic patients. Although these severity influences are small (2%-5% of the variance in SGRQ score), they do suggest that pre-specified separate analyses are warranted to test for differences in response, based on baseline severity. PMID:28848922

Improved estimation of subject-level functional connectivity using full and partial correlation with empirical Bayes shrinkage.

PubMed

Mejia, Amanda F; Nebel, Mary Beth; Barber, Anita D; Choe, Ann S; Pekar, James J; Caffo, Brian S; Lindquist, Martin A

2018-05-15

Reliability of subject-level resting-state functional connectivity (FC) is determined in part by the statistical techniques employed in its estimation. Methods that pool information across subjects to inform estimation of subject-level effects (e.g., Bayesian approaches) have been shown to enhance reliability of subject-level FC. However, fully Bayesian approaches are computationally demanding, while empirical Bayesian approaches typically rely on using repeated measures to estimate the variance components in the model. Here, we avoid the need for repeated measures by proposing a novel measurement error model for FC describing the different sources of variance and error, which we use to perform empirical Bayes shrinkage of subject-level FC towards the group average. In addition, since the traditional intra-class correlation coefficient (ICC) is inappropriate for biased estimates, we propose a new reliability measure denoted the mean squared error intra-class correlation coefficient (ICC MSE ) to properly assess the reliability of the resulting (biased) estimates. We apply the proposed techniques to test-retest resting-state fMRI data on 461 subjects from the Human Connectome Project to estimate connectivity between 100 regions identified through independent components analysis (ICA). We consider both correlation and partial correlation as the measure of FC and assess the benefit of shrinkage for each measure, as well as the effects of scan duration. We find that shrinkage estimates of subject-level FC exhibit substantially greater reliability than traditional estimates across various scan durations, even for the most reliable connections and regardless of connectivity measure. Additionally, we find partial correlation reliability to be highly sensitive to the choice of penalty term, and to be generally worse than that of full correlations except for certain connections and a narrow range of penalty values. This suggests that the penalty needs to be chosen carefully when using partial correlations. Copyright © 2018. Published by Elsevier Inc.

FTM-West : fuel treatment market model for U.S. West

Treesearch

Peter J. Ince; Andrew Kramp; Henry Spelter; Ken Skog; Dennis Dykstra

2006-01-01

This paper presents FTM–West, a partial market equilibrium model designed to project future wood market impacts of significantly expanded fuel treatment programs that could remove trees to reduce fire hazard on forestlands in the U.S. West. FTM–West was designed to account for structural complexities in marketing and utilization that arise from unconventional size...

Collection and curation of IDPs in the stratosphere and below. Part 2: The Greenland and Antarctic ice sheets

NASA Technical Reports Server (NTRS)

Maurette, Michel; Hammer, C.; Harvey, R.; Immel, G.; Kurat, G.; Taylor, S.

1994-01-01

In a companion paper, Zolensky discusses interplanetary dust particles (IDP's) collected in the stratosphere. Here, we describe the recovery of much larger unmelted to partially melted IDP's from the Greenland and Antarctica ice sheet, and discuss problems arising in their collection and curation, as well as future prospects for tackling these problems.

The relative nature of fertilization success: Implications for the study of post-copulatory sexual selection

PubMed Central

2008-01-01

Background The determination of genetic variation in sperm competitive ability is fundamental to distinguish between post-copulatory sexual selection models based on good-genes vs compatible genes. The sexy-sperm and the good-sperm hypotheses for the evolution of polyandry require additive (intrinsic) effects of genes influencing sperm competitiveness, whereas the genetic incompatibility hypothesis invokes non-additive genetic effects. A male's sperm competitive ability is typically estimated from his fertilization success, a measure that is dependent on the ability of rival sperm competitors to fertilize the ova. It is well known that fertilization success may be conditional to genotypic interactions among males as well as between males and females. However, the consequences of effects arising from the random sampling of sperm competitors upon the estimation of genetic variance in sperm competitiveness have been overlooked. Here I perform simulations of mating trials performed in the context of sibling analysis to investigate whether the ability to detect additive genetic variance underlying the sperm competitiveness phenotype is hindered by the relative nature of fertilization success measurements. Results Fertilization success values render biased sperm competitive ability values. Furthermore, asymmetries among males in the errors committed when estimating sperm competitive abilities are likely to exist as long as males exhibit variation in sperm competitiveness. Critically, random effects arising from the relative nature of fertilization success lead to an underestimation of underlying additive genetic variance in sperm competitive ability. Conclusion The results show that, regardless of the existence of genotypic interactions affecting the output of sperm competition, fertilization success is not a perfect predictor of sperm competitive ability because of the stochasticity of the background used to obtain fertilization success measures. Random effects need to be considered in the debate over the maintenance of genetic variation in sperm competitiveness, and when testing good-genes and compatible-genes processes as explanations of polyandrous behaviour using repeatability/heritability data in sperm competitive ability. These findings support the notion that the genetic incompatibility hypothesis needs to be treated as an alternative hypothesis, rather than a null hypothesis, in studies that fail to detect intrinsic sire effects on the sperm competitiveness phenotype. PMID:18474087

A model for the microwave emissivity of the ocean's surface as a function of wind speed

NASA Technical Reports Server (NTRS)

Wilheit, T. T.

1979-01-01

A quanitative model is presented which describes the ocean surface as a ensemble of flat facets with a normal distribution of slopes. The variance of the slope distribution is linearly related to frequency up to 35 GHz and constant at higher frequencies. These facets are partially covered with an absorbing nonpolarized foam layer. Experimental evidence is presented for this model.

Ultrasonographic findings of Kimura's disease presenting in the upper extremities.

PubMed

Shin, Gi Won; Lee, Sun Joo; Choo, Hye Jung; Park, Young Mi; Jeong, Hae Woong; Lee, Sung-Moon; Suh, Jin-Suck; Jung, Soo-Jin

2014-12-01

To describe ultrasound findings of Kimura's disease arising in the upper extremities. Five patients with Kimura's disease confirmed by surgical resection were retrospectively reviewed by two musculoskeletal radiologists and a pathologist. All six lesions involved the epitrochlear area and appeared as partially (n = 5) or poorly (n = 1) marginated subcutaneous masses with the presence of curvilinear hyperechoic bands intermingled within the hypoechoic components by US. Moderate (n = 4) to severe (n = 2) vascular signals were observed in some proportion of the hyperechoic bands by color Doppler US. The associated findings were the increased echogenicity of surrounding subcutaneous fat (n = 6) and adjacent lymphadenopathy (n = 4). Microscopic examination showed proliferation of lymphoid follicles with prominent germinal centers and intervening fibrosis. In this study, Kimura's disease arising in the upper extremities showed a partially defined hypoechoic subcutaneous mass with internal hyperechoic bands and moderate-to-severe vascularities, increased echogenicity of the surrounding subcutaneous fat and adjacent lymphadenopathy on US. Thus, when these US features are observed in the typical epitrochlear region of an Asian individual, especially if accompanied by peripheral eosinophilia, Kimura's disease should be considered as a possible diagnosis.

Movement Disorders Induced by the "Atypical" Antipsychotic Aripiprazole.

PubMed

Selfani, Karim; Soland, Valérie L; Chouinard, Sylvain; Huot, Philippe

2017-01-01

Aripiprazole is an antipsychotic that acts as a partial agonist at dopamine D2 receptors. Because of its partial agonist activity, it was believed that aripiprazole would be less susceptible than typical antipsychotics to induce extrapyramidal side effects. However, a few case-reports and case-series detailing aripiprazole-induced movement disorders have been published, suggesting that aripiprazole-induced movement disorders may arise. Here, we seek to report further cases of aripiprazole-induced movement disorders to raise the awareness of clinicians on this adverse effect. Patients referred to the André-Barbeau Movement Disorder clinic treated with aripiprazole were enrolled in this study. Their charts were retrospectively reviewed and data regarding past psychiatric history, past antipsychotic medication, duration of aripiprazole treatment, daily dose of aripiprazole administered, and resulting movement disorders were collected. We report 14 cases of parkinsonism, tardive dyskinesia and akathisia induced by aripiprazole. Some of these, mostly the parkinsonian phenotype, abated spontaneously following drug discontinuation, whereas others, mostly related to tardive phenomena, persisted after aripiprazole was discontinued, and required treatment. This case-series adds to the existing literature that suggests that movement disorders may arise following treatment with aripiprazole. Clinicians should be aware of this potential side effect when prescribing aripiprazole to patients.

Solitary Hepatocellular Carcinoma Fed by the Cystic Artery: Limitation of Transcatheter Arterial Embolization

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

Hirota, Shozo; Matsumoto, Shinichi; Fukuda, Tetsuya

1999-05-15

Purpose: To clarify the limitations of transcatheter treatment for hepatocellular carcinoma (HCC) with parasitic feeders from the cystic artery. Methods: Three male patients had a solitary HCC (average diameter 3 cm) fed by the cystic artery among 221 patients with HCC from 1994 to 1997. One tumor was nourished entirely from the cystic artery arising from the medial branch of the left hepatic artery, and two tumors were fed partially by the cystic arteries arising from the anterior inferior branch of the right hepatic artery. We analyzed the indications for transcatheter treatment for these three patients. Results: We chose notmore » to embolize the cystic artery for fear of necrosis of the gallbladder. Although embolization of the anterior branch of the right hepatic artery was performed in one patient with a tumor fed partially by the cystic artery, only half the tumor was embolized. Two patients underwent hepatic resection, and one received percutaneous ethanol injection therapy. At follow-up of 28-40 months (average 33 months) all patients are alive. Conclusion: Feeding by the cystic artery represents a limitation of TAE for HCC.« less

Intimate partner aggression and women's work outcomes.

PubMed

LeBlanc, Manon Mireille; Barling, Julian; Turner, Nick

2014-10-01

Using conservation of resources theory, we examined the relationship between intimate partner aggression enacted against heterosexual women and 3 types of work-related outcomes for these women: withdrawal while at work (i.e., cognitive distraction, work neglect), withdrawal from work (i.e., partial absenteeism, intentions to quit), and performance. In Study 1, we compared withdrawal both at and from work across 3 clinically categorized groups of women (n = 50), showing that experiencing physical aggression is related to higher work neglect. We replicated and extended these findings in Study 2 using a community sample of employed women (n = 249) by considering the incremental variance explained by both physical aggression and psychological aggression on these same outcomes. Results showed that physical aggression predicted higher levels of withdrawal both at and from work, with psychological aggression predicting additional variance in partial absenteeism over and above the effects of physical aggression. Study 3 extended the model to include academic performance as an outcome in a sample of female college students (n = 122) in dating relationships. Controlling for the women's conscientiousness, psychological aggression predicted lower academic performance after accounting for the effects of physical aggression. We discuss theoretical and practical implications of these results, as well as directions for future research. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Neuroticism (not depressive symptoms) predicts memory complaints in some community-dwelling older adults.

PubMed

Merema, Matt R; Speelman, Craig P; Foster, Jonathan K; Kaczmarek, Elizabeth A

2013-08-01

To examine whether depressive symptoms are useful predictors of subjective memory complaints in community-dwelling older adults, beyond the predictive utility already provided by memory performance and characteristics of personality. Using hierarchical regression, we examined the relationship between depressive symptoms and subjective memory complaints, controlling for age, gender, education, memory performance, conscientiousness, and neuroticism. Community-dwelling older adults aged 66 to 90 years (N = 177) who responded to a newspaper advertisement for a memory study in Perth, Western Australia. The General Frequency of Forgetting scale (for memory complaints), Depression Anxiety Stress Scales (for depressive symptoms), NEO-Five Factor Inventory (for conscientiousness and neuroticism), and the Visual Reproduction and Logical Memory subtests from the Wechsler Memory Scale-4th Edition (for visual and verbal memory). The hierarchical regression analysis indicated that while depressive symptoms significantly predicted memory complaints after variance associated with age, gender, education, memory performance, and conscientiousness was partialled out, they accounted for almost none of the variance in complaints when neuroticism was partialled out. The well-established relationship between depression and memory complaints may exist in some community-dwelling older adult populations only on account of the manner in which both are associated with neuroticism. Copyright © 2013 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

Spatial distribution of antibodies to Salmonella enterica serovar Typhimurium O antigens in bulk milk from Texas dairy herds.

PubMed

Graham, S L; Barling, K S; Waghela, S; Scott, H M; Thompson, J A

2005-06-10

Environmental factors that enhance either the survivability or dispersion of Salmonella enterica serovar Typhimurium (S. Typhimurium) could result in a spatial pattern of disease risk. The objectives of this study were to: (1) describe herd status based on antibody response to Salmonella Typhimurium as estimated from bulk tank milk samples and (2) to describe the resulting geographical patterns found among Texas dairy herds. Eight hundred and fifty-two bulk milk samples were collected from georeferenced dairy farms and assayed by an indirect enzyme-linked immunosorbent assay (ELISA) using S. Typhimurium lipopolysaccharide (LPS). ELISA signal-to-noise ratios for each bulk tank milk sample were calculated and used for geostatistical analyses. Best-fit parameters for the exponential theoretical variogram included a range of 438.8 km, partial sill of 0.060 and nugget of 0.106. The partial sill is the classical geostatistical term for the variance that can be explained by the herd's location and the nugget is the spatially random component of the variance. We have identified a spatial process in bulk milk tank titers for S. Typhimurium in Texas dairy herds and present a map of the expected smoothed surface. Areas with higher expected titers should be targeted in further studies on controlling Salmonella infection with environmental modifications.

Why add anything to nothing? The arcsine difference as a measure of treatment effect in meta-analysis with zero cells.

PubMed

Rücker, Gerta; Schwarzer, Guido; Carpenter, James; Olkin, Ingram

2009-02-28

For clinical trials with binary endpoints there are a variety of effect measures, for example risk difference, risk ratio and odds ratio (OR). The choice of metric is not always straightforward and should reflect the clinical question. Additional issues arise if the event of interest is rare. In systematic reviews, trials with zero events in both arms are encountered and often excluded from the meta-analysis.The arcsine difference (AS) is a measure which is rarely considered in the medical literature. It appears to have considerable promise, because it handles zeros naturally, and its asymptotic variance does not depend on the event probability.This paper investigates the pros and cons of using the AS as a measure of intervention effect. We give a pictorial representation of its meaning and explore its properties in relation to other measures. Based on analytical calculation of the variance of the arcsine transformation, a more conservative variance estimate for the rare event setting is proposed. Motivated by a published meta-analysis in cardiac surgery, we examine the statistical properties of the various metrics in the rare event setting.We find the variance estimate of the AS to be more stable than that of the log-OR, even if events are rare. However, parameter estimation is biased if the groups are markedly unbalanced. Though, from a theoretical viewpoint, the AS is a natural choice, its practical use is likely to continue to be limited by its less direct interpretation. Copyright (c) 2008 John Wiley & Sons, Ltd.

Spatial eigenmodes and synchronous oscillation: co-incidence detection in simulated cerebral cortex.

PubMed

Chapman, Clare L; Wright, James J; Bourke, Paul D

2002-07-01

Zero-lag synchronisation arises between points on the cerebral cortex receiving concurrent independent inputs; an observation generally ascribed to nonlinear mechanisms. Using simulations of cerebral cortex and Principal Component Analysis (PCA) we show patterns of zero-lag synchronisation (associated with empirically realistic spectral content) can arise from both linear and nonlinear mechanisms. For low levels of activation, we show the synchronous field is described by the eigenmodes of the resultant damped wave activity. The first and second spatial eigenmodes (which capture most of the signal variance) arise from the even and odd components of the independent input signals. The pattern of zero-lag synchronisation can be accounted for by the relative dominance of the first mode over the second, in the near-field of the inputs. The simulated cortical surface can act as a few millisecond response coincidence detector for concurrent, but uncorrelated, inputs. As cortical activation levels are increased, local damped oscillations in the gamma band undergo a transition to highly nonlinear undamped activity with 40 Hz dominant frequency. This is associated with "locking" between active sites and spatially segregated phase patterns. The damped wave synchronisation and the locked nonlinear oscillations may combine to permit fast representation of multiple patterns of activity within the same field of neurons.

Impact of flavor attributes on consumer liking of Swiss cheese.

PubMed

Liggett, R E; Drake, M A; Delwiche, J F

2008-02-01

Although Swiss cheese is growing in popularity, no research has examined what flavor characteristics consumers desire in Swiss cheese, which was the main objective of this study. To this end, a large group of commercially available Swiss-type cheeses (10 domestic Swiss cheeses, 4 domestic Baby Swiss cheeses, and one imported Swiss Emmenthal) were assessed both by 12 trained panelists for flavor and feeling factors and by 101 consumers for overall liking. In addition, a separate panel of 24 consumers rated the same cheeses for dissimilarity. On the basis of liking ratings, the 101 consumers were segmented by cluster analysis into 2 groups: nondistinguishers (n = 40) and varying responders (n = 61). Partial least squares regression, a statistical modeling technique that relates 2 data sets (in this case, a set of descriptive analysis data and a set of consumer liking data), was used to determine which flavor attributes assessed by the trained panel were important variables in overall liking of the cheeses for the varying responders. The model explained 93% of the liking variance on 3 normally distributed components and had 49% predictability. Diacetyl, whey, milk fat, and umami were found to be drivers of liking, whereas cabbage, cooked, and vinegar were drivers of disliking. Nutty flavor was not particularly important to liking and it was present in only 2 of the cheeses. The dissimilarity ratings were combined with the liking ratings of both segments and analyzed by probabilistic multidimensional scaling. The ideals of each segment completely overlapped, with the variance of the varying responders being smaller than the variance of the non-distinguishers. This model indicated that the Baby Swiss cheeses were closer to the consumers' ideals than were the other cheeses. Taken together, the 2 models suggest that the partial least squares regression failed to capture one or more attributes that contribute to consumer acceptance, although the descriptive analysis of flavor and feeling factors was able to account for 93% of the variance in the liking ratings. These findings indicate the flavor characteristics Swiss cheese producers should optimize, and minimize, to create cheeses that best match consumer desires.

Separation of Trend and Chaotic Components of Time Series and Estimation of Their Characteristics by Linear Splines

NASA Astrophysics Data System (ADS)

Kryanev, A. V.; Ivanov, V. V.; Romanova, A. O.; Sevastyanov, L. A.; Udumyan, D. K.

2018-03-01

This paper considers the problem of separating the trend and the chaotic component of chaotic time series in the absence of information on the characteristics of the chaotic component. Such a problem arises in nuclear physics, biomedicine, and many other applied fields. The scheme has two stages. At the first stage, smoothing linear splines with different values of smoothing parameter are used to separate the "trend component." At the second stage, the method of least squares is used to find the unknown variance σ2 of the noise component.

Factors influencing Australian agricultural workers' self-efficacy using chemicals in the workplace.

PubMed

Blackman, Ian R

2012-11-01

A hypothetical model was formulated to explore which factors can simultaneously influence the self-reported ability of agricultural employees to embrace chemical safety practices. Eight variables were considered in the study, including the employees' gender, age, duration of current employment status, and whether they were employed full-time or part-time. The self-efficacy measures of 169 participants were then estimated by measuring their self-rated ability to understand and perform different chemical safety practices. Models identifying employee self-efficacy pathways leading to worker readiness to engage in chemical safety were then tested using Partial Least Squares Path Analysis. Study results suggest that employees' self-efficacy to successfully engage in safe chemical practices in their workplace can be directly predicted by four variables, with additional indirect effects offered by one other variable, which cumulatively account for 41% of the variance of employees' chemical safety self-efficacy scores. The most significant predictor variables that directly influenced employees' self-efficacy in adopting chemical safety practices in the workplace were worker age, gender, years of employment, and concurrent confidence (self-efficacy) arising from prior experience using chemicals in the workplace. The variables of employees' prior knowledge and understanding about the use of administrative controls and personal protective equipment to protect workers from chemical exposure had no direct influence on self-efficacy to handle chemical emergencies. Employees' unfamiliarity with risk control strategies and reliance on material safety data sheets for information suggest that ongoing and targeted training are necessary if chemical safety issues are to be addressed.

Extra-anatomic endovascular repair of an abdominal aortic aneurysm with a horseshoe kidney supplied by the aneurysmal aorta.

PubMed

Rey, Jorge; Golpanian, Samuel; Yang, Jane K; Moreno, Enrique; Velazquez, Omaida C; Goldstein, Lee J; Chahwala, Veer

2015-07-01

Abdominal aortic aneurysm complicated by a horseshoe kidney (HSK, fused kidney) represents a unique challenge for repair. Renal arteries arising from the aneurysmal aorta can further complicate intervention. Reports exist describing the repair of these complex anatomies using fenestrated endografts, hybrid open repairs (debranching), and open aneurysmorrhaphy with preservation of renal circulation. We describe an extra-anatomic, fully endovascular repair of an abdominal aortic aneurysm with a HSK partially supplied by a renal artery arising from the aneurysm. We successfully applied aortouni-iliac endografting, femorofemoral bypass, and retrograde renal artery perfusion via the contralateral femoral artery to exclude the abdominal aortic aneurysm and preserve circulation to the HSK. Copyright © 2015 Elsevier Inc. All rights reserved.

Measurement of Inclusive Radiative B-Meson Decays with a Photon Energy Threshold of 1.7 GeV

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

Limosani, A.; Barberio, E.; Julius, T.

2009-12-11

Using 605 fb{sup -1} of data collected at the UPSILON(4S) resonance we present a measurement of the inclusive radiative B-meson decay channel, B->X{sub s}gamma. For the lower photon energy thresholds of 1.7, 1.8, 1.9, and 2.0 GeV, as defined in the rest frame of the B meson, we measure the partial branching fraction and the mean and variance of the photon energy spectrum. At the 1.7 GeV threshold we obtain the partial branching fraction BF(B->X{sub s}gamma)=(3.45+-0.15+-0.40)x10{sup -4}, where the errors are statistical and systematic.

A new approach to treat discontinuities in multi-layered soils

NASA Astrophysics Data System (ADS)

Berardi, Marco; Difonzo, Fabio; Caputo, Maria; Vurro, Michele; Lopez, Luciano

2017-04-01

The water infiltration into two (or more) layered soils can give rise to preferential flow paths at the interface between different soils. The deep understanding of this phenomenon can be of great interest in modeling different environmental problems in geosciences and hydrology. Flow through layered soils arises naturally in agriculture, and layered soils are also engineered as cover liners for landfills. In particular, the treatment of the soil discontinuity is of great interest from the modeling and the numerical point of view, and is still an open problem.% (see, for example, te{Matthews_et_al,Zha_vzj_2013,DeLuca_Cepeda_ASCE_2016}). Assuming to approximate the soils with different porous media, the governing equation for this phenomenon is Richards' equation, in the following form: {eq:different_Richards_1} C_1(ψ) partial ψ/partial t = partial /partial z [ K_1(ψ) ( partial ψ/partial z - 1 ) ], \\quad if \\quad z < \\overline{z}, C_2(ψ) partial ψ/partial t = partial /partial z [ K_2(ψ) ( partial ψ/partial z - 1 ) ], \\quad if \\quad z > \\overline{z}, where \\overline{z} is the spatial threshold that identifies the change in soil structure, and C1 C_2, K_1, K_2, the hydraulic functions that describe the upper and the lower soil, respectively. The ψ-based form is used, in this work. Here we have used the Filippov's theory in order to deal with discontinuous differential systems, and we handled opportunely the numerical discretization in order to treat the abovementioned system by means of this theory, letting the discontinuity depend on the state variable. The advantage of this technique is a better insight on the solution behavior on the discontinuity surface, and the no-need to average the hydraulic conductivity field on the threshold itself, as in the existing literature.

The new patient with a first seizure.

PubMed

King, Mark

2003-04-01

First seizures are common, with one in 20 people suffering a seizure at some time in their life. This article aims to outline the assessment of patients with a first seizure, including making an accurate diagnosis of both seizure type and an epilepsy syndrome, if present. Seizures are classified into generalised and partial (arising from a focal region in the brain) based on clinical and electroencephalogram findings. However, as a partial seizure may proceed to a tonic clonic phase, differentiation may be difficult. Inquiring directly about 'minor' epileptic symptoms before the episode such as absences, myoclonic jerks, visual or auditory hallucinations or feelings of déjà vu, is needed to attempt to make a epilepsy syndrome diagnosis, as this has practical implications for treatment, prognosis and genetic counselling. Generalised epilepsies should be treated initially with valproate, while partial epilepsies should be treated with carbamazepine and switched to newer agents if intolerance occurs.

Pancreas anatomy and surgical procedure for pancreatectomy in rhesus monkeys.

PubMed

Zhang, Yi; Fu, Lan; Lu, Yan-Rong; Guo, Zhi-Guang; Zhang, Zhao-Da; Cheng, Jing-Qiu; Hu, Wei-Ming; Liu, Xu-Bao; Mai, Gang; Zeng, Yong; Tian, Bo-Le

2011-12-01

The aim of this study was to investigate the pancreas anatomy and surgical procedure for harvesting pancreas for islet isolation while performing pancreatectomy to induce diabetes in rhesus monkeys. The necropsy was performed in three cadaveric monkeys. Two monkeys underwent the total pancreatectomy and four underwent partial pancreatectomy (70-75%). The greater omentum without ligament to transverse colon, the cystic artery arising from the proper hepatic artery and the branches supplying the paries posterior gastricus from the splenic artery were observed. For pancreatectomy, resected pancreas can be used for islet isolation. Diabetes was not induced in the monkeys undergoing partial pancreatectomy (70-75%). Pancreas anatomy in rhesus monkeys is not the same as in human. Diabetes can be induced in rhesus monkeys by total but not partial pancreatectomy (70-75%). Resected pancreas can be used for islet isolation while performing pancreatectomy to induce diabetes. © 2011 John Wiley & Sons A/S.

Partial regularity of weak solutions to a PDE system with cubic nonlinearity

NASA Astrophysics Data System (ADS)

Liu, Jian-Guo; Xu, Xiangsheng

2018-04-01

In this paper we investigate regularity properties of weak solutions to a PDE system that arises in the study of biological transport networks. The system consists of a possibly singular elliptic equation for the scalar pressure of the underlying biological network coupled to a diffusion equation for the conductance vector of the network. There are several different types of nonlinearities in the system. Of particular mathematical interest is a term that is a polynomial function of solutions and their partial derivatives and this polynomial function has degree three. That is, the system contains a cubic nonlinearity. Only weak solutions to the system have been shown to exist. The regularity theory for the system remains fundamentally incomplete. In particular, it is not known whether or not weak solutions develop singularities. In this paper we obtain a partial regularity theorem, which gives an estimate for the parabolic Hausdorff dimension of the set of possible singular points.

Multi-region relaxed Hall magnetohydrodynamics with flow

DOE PAGES

Lingam, Manasvi; Abdelhamid, Hamdi M.; Hudson, Stuart R.

2016-08-03

The recent formulations of multi-region relaxed magnetohydrodynamics (MRxMHD) have generalized the famous Woltjer-Taylor states by incorporating a collection of “ideal barriers” that prevent global relaxation and flow. In this paper, we generalize MRxMHD with flow to include Hall effects, and thereby obtain the partially relaxed counterparts of the famous double Beltrami states as a special subset. The physical and mathematical consequences arising from the introduction of the Hall term are also presented. We demonstrate that our results (in the ideal MHD limit) constitute an important subset of ideal MHD equilibria, and we compare our approach against other variational principles proposedmore » for deriving the partially relaxed states.« less

Identification of 15 novel partial SHOX deletions and 13 partial duplications, and a review of the literature reveals intron 3 to be a hotspot region.

PubMed

Benito-Sanz, Sara; Belinchon-Martínez, Alberta; Aza-Carmona, Miriam; de la Torre, Carolina; Huber, Celine; González-Casado, Isabel; Ross, Judith L; Thomas, N Simon; Zinn, Andrew R; Cormier-Daire, Valerie; Heath, Karen E

2017-02-01

Short stature homeobox gene (SHOX) is located in the pseudoautosomal region 1 of the sex chromosomes. It encodes a transcription factor implicated in the skeletal growth. Point mutations, deletions or duplications of SHOX or its transcriptional regulatory elements are associated with two skeletal dysplasias, Léri-Weill dyschondrosteosis (LWD) and Langer mesomelic dysplasia (LMD), as well as in a small proportion of idiopathic short stature (ISS) individuals. We have identified a total of 15 partial SHOX deletions and 13 partial SHOX duplications in LWD, LMD and ISS patients referred for routine SHOX diagnostics during a 10 year period (2004-2014). Subsequently, we characterized these alterations using MLPA (multiplex ligation-dependent probe amplification assay), fine-tiling array CGH (comparative genomic hybridation) and breakpoint PCR. Nearly half of the alterations have a distal or proximal breakpoint in intron 3. Evaluation of our data and that in the literature reveals that although partial deletions and duplications only account for a small fraction of SHOX alterations, intron 3 appears to be a breakpoint hotspot, with alterations arising by non-allelic homologous recombination, non-homologous end joining or other complex mechanisms.

CS-duration and partial-reinforcement effects counteract overshadowing in select situations

PubMed Central

Urushihara, Kouji; Miller, Ralph R.

2008-01-01

Two experiments used rats in a conditioned lick suppression preparation to investigate how the conditioned stimulus (CS)-duration and partial-reinforcement effects (i.e., weakened responding due to conditioning with a CS of longer duration and presenting nonreinforced CSs intermingled with CS-unconditioned stimulus [US] pairings, respectively) interact with overshadowing. Experiment 1 found that when overshadowing treatment was combined with either extended CS duration or partial reinforcement, the response deficit was weaker than when either of these three treatments was administered alone. In Experiment 2, the generality of the findings in Experiment 1 was investigated by replicating it with various US-US intervals. This time counteraction was observed only when both the absolute duration of total CS exposure and the US-US interval were short. The results support neither the view that the ratio between the total CS exposure and total time in the context determines the CS-duration and the partial-reinforcement effects nor the view that these two effects arise from a loss of effectiveness of the excitatory CS-US association during CS-alone exposures in partial reinforcement or early periods of CS exposure with long CSs. PMID:18047218

Heritability of Performance Deficit Accumulation During Acute Sleep Deprivation in Twins

PubMed Central

Kuna, Samuel T.; Maislin, Greg; Pack, Frances M.; Staley, Bethany; Hachadoorian, Robert; Coccaro, Emil F.; Pack, Allan I.

2012-01-01

Study Objectives: To determine if the large and highly reproducible interindividual differences in rates of performance deficit accumulation during sleep deprivation, as determined by the number of lapses on a sustained reaction time test, the Psychomotor Vigilance Task (PVT), arise from a heritable trait. Design: Prospective, observational cohort study. Setting: Academic medical center. Participants: There were 59 monozygotic (mean age 29.2 ± 6.8 [SD] yr; 15 male and 44 female pairs) and 41 dizygotic (mean age 26.6 ± 7.6 yr; 15 male and 26 female pairs) same-sex twin pairs with a normal polysomnogram. Interventions: Thirty-eight hr of monitored, continuous sleep deprivation. Measurements and Results: Patients performed the 10-min PVT every 2 hr during the sleep deprivation protocol. The primary outcome was change from baseline in square root transformed total lapses (response time ≥ 500 ms) per trial. Patient-specific linear rates of performance deficit accumulation were separated from circadian effects using multiple linear regression. Using the classic approach to assess heritability, the intraclass correlation coefficients for accumulating deficits resulted in a broad sense heritability (h2) estimate of 0.834. The mean within-pair and among-pair heritability estimates determined by analysis of variance-based methods was 0.715. When variance components of mixed-effect multilevel models were estimated by maximum likelihood estimation and used to determine the proportions of phenotypic variance explained by genetic and nongenetic factors, 51.1% (standard error = 8.4%, P < 0.0001) of twin variance was attributed to combined additive and dominance genetic effects. Conclusion: Genetic factors explain a large fraction of interindividual variance among rates of performance deficit accumulations on PVT during sleep deprivation. Citation: Kuna ST; Maislin G; Pack FM; Staley B; Hachadoorian R; Coccaro EF; Pack AI. Heritability of performance deficit accumulation during acute sleep deprivation in twins. SLEEP 2012;35(9):1223-1233. PMID:22942500

Parent of origin, mosaicism, and recurrence risk: probabilistic modeling explains the broken symmetry of transmission genetics.

PubMed

Campbell, Ian M; Stewart, Jonathan R; James, Regis A; Lupski, James R; Stankiewicz, Paweł; Olofsson, Peter; Shaw, Chad A

2014-10-02

Most new mutations are observed to arise in fathers, and increasing paternal age positively correlates with the risk of new variants. Interestingly, new mutations in X-linked recessive disease show elevated familial recurrence rates. In male offspring, these mutations must be inherited from mothers. We previously developed a simulation model to consider parental mosaicism as a source of transmitted mutations. In this paper, we extend and formalize the model to provide analytical results and flexible formulas. The results implicate parent of origin and parental mosaicism as central variables in recurrence risk. Consistent with empirical data, our model predicts that more transmitted mutations arise in fathers and that this tendency increases as fathers age. Notably, the lack of expansion later in the male germline determines relatively lower variance in the proportion of mutants, which decreases with paternal age. Subsequently, observation of a transmitted mutation has less impact on the expected risk for future offspring. Conversely, for the female germline, which arrests after clonal expansion in early development, variance in the mutant proportion is higher, and observation of a transmitted mutation dramatically increases the expected risk of recurrence in another pregnancy. Parental somatic mosaicism considerably elevates risk for both parents. These findings have important implications for genetic counseling and for understanding patterns of recurrence in transmission genetics. We provide a convenient online tool and source code implementing our analytical results. These tools permit varying the underlying parameters that influence recurrence risk and could be useful for analyzing risk in diverse family structures. Copyright © 2014 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Reactive transport in a partially molten system with binary solid solution

NASA Astrophysics Data System (ADS)

Jordan, J.; Hesse, M. A.

2017-12-01

Melt extraction from the Earth's mantle through high-porosity channels is required to explain the composition of the oceanic crust. Feedbacks from reactive melt transport are thought to localize melt into a network of high-porosity channels. Recent studies invoke lithological heterogeneities in the Earth's mantle to seed the localization of partial melts. Therefore, it is necessary to understand the reaction fronts that form as melt flows across the lithological interface of a heterogeneity and the background mantle. Simplified melting models of such systems aide in the interpretation and formulation of larger scale mantle models. Motivated by the aforementioned facts, we present a chromatographic analysis of reactive melt transport across lithological boundaries, using theory for hyperbolic conservation laws. This is an extension of well-known linear trace element chromatography to the coupling of major elements and energy transport. Our analysis allows the prediction of the feedbacks that arise in reactive melt transport due to melting, freezing, dissolution and precipitation for frontal reactions. This study considers the simplified case of a rigid, partially molten porous medium with binary solid solution. As melt traverses a lithological contact-modeled as a Riemann problem-a rich set of features arise, including a reacted zone between an advancing reaction front and partial chemical preservation of the initial contact. Reactive instabilities observed in this study originate at the lithological interface rather than along a chemical gradient as in most studies of mantle dynamics. We present a regime diagram that predicts where reaction fronts become unstable, thereby allowing melt localization into high-porosity channels through reactive instabilities. After constructing the regime diagram, we test the one-dimensional hyperbolic theory against two-dimensional numerical experiments. The one-dimensional hyperbolic theory is sufficient for predicting the qualitative behavior of reactive melt transport simulations conducted in two-dimensions. The theoretical framework presented can be extended to more complex and realistic phase behavior, and is therefore a useful tool for understanding nonlinear feedbacks in reactive melt transport problems relevant to mantle dynamics.

Quantal amplitude and quantal variance of strontium-induced asynchronous EPSCs in rat dentate granule neurons

PubMed Central

Bekkers, John M; Clements, John D

1999-01-01

Excitatory postsynaptic currents (EPSCs) were recorded from granule cells of the dentate gyrus in acute slices of 17- to 21-day-old rats (22-25 °C) using tissue cuts and minimal extracellular stimulation to selectively activate a small number of synaptic contacts.Adding millimolar Sr2+ to the external solution produced asynchronous EPSCs (aEPSCs) lasting for several hundred milliseconds after the stimulus. Minimally stimulated aEPSCs resembled miniature EPSCs (mEPSCs) recorded in the same cell but differed from them in ways expected from the greater range of dendritic filtering experienced by mEPSCs. aEPSCs had the same stimulus threshold as the synchronous EPSCs (sEPSCs) that followed the stimulus with a brief latency. aEPSCs following stimulation of distal inputs had a slower mean rise time than those following stimulation of proximal inputs. These results suggest that aEPSCs arose from the same synapses that generated sEPSCs.Proximally elicited aEPSCs had a mean amplitude of 6.7 ± 2.2 pA (± s.d., n = 23 cells) at -70 mV and an amplitude coefficient of variation of 0.46 ± 0.08.The amplitude distributions of sEPSCs never exhibited distinct peaks.Monte Carlo modelling of the shapes of aEPSC amplitude distributions indicated that our data were best explained by an intrasite model of quantal variance.It is concluded that Sr2+-evoked aEPSCs are uniquantal events arising at synaptic terminals that were recently invaded by an action potential, and so provide direct information about the quantal amplitude and quantal variance at those terminals. The large quantal variance obscures quantization of the amplitudes of evoked sEPSCs at this class of excitatory synapse. PMID:10066937

Dependency-dependent interference: NPI interference, agreement attraction, and global pragmatic inferences.

PubMed

Xiang, Ming; Grove, Julian; Giannakidou, Anastasia

2013-01-01

Previous psycholinguistics studies have shown that when forming a long distance dependency in online processing, the parser sometimes accepts a sentence even though the required grammatical constraints are only partially met. A mechanistic account of how such errors arise sheds light on both the underlying linguistic representations involved and the processing mechanisms that put such representations together. In the current study, we contrast the negative polarity items (NPI) interference effect, as shown by the acceptance of an ungrammatical sentence like "The bills that democratic senators have voted for will ever become law," with the well-known phenomenon of agreement attraction ("The key to the cabinets are … "). On the surface, these two types of errors look alike and thereby can be explained as being driven by the same source: similarity based memory interference. However, we argue that the linguistic representations involved in NPI licensing are substantially different from those of subject-verb agreement, and therefore the interference effects in each domain potentially arise from distinct sources. In particular, we show that NPI interference at least partially arises from pragmatic inferences. In a self-paced reading study with an acceptability judgment task, we showed NPI interference was modulated by participants' general pragmatic communicative skills, as quantified by the Autism-Spectrum Quotient (AQ, Baron-Cohen et al., 2001), especially in offline tasks. Participants with more autistic traits were actually less prone to the NPI interference effect than those with fewer autistic traits. This result contrasted with agreement attraction conditions, which were not influenced by individual pragmatic skill differences. We also show that different NPI licensors seem to have distinct interference profiles. We discuss two kinds of interference effects for NPI licensing: memory-retrieval based and pragmatically triggered.

Waveform modeling of the seismic response of a mid-ocean ridge axial melt sill

NASA Astrophysics Data System (ADS)

Xu, Min; Stephen, R. A.; Canales, J. Pablo

2017-12-01

Seismic reflections from axial magma lens (AML) are commonly observed along many mid-ocean ridges, and are thought to arise from the negative impedance contrast between a solid, high-speed lid and the underlying low-speed, molten or partially molten (mush) sill. The polarity of the AML reflection ( P AML P) at vertical incidence and the amplitude vs offset (AVO) behavior of the AML reflections (e.g., P AML P and S-converted P AML S waves) are often used as a diagnostic tool for the nature of the low-speed sill. Time-domain finite difference calculations for two-dimensional laterally homogeneous models show some scenarios make the interpretation of melt content from partial-offset stacks of P- and S-waves difficult. Laterally heterogeneous model calculations indicate diffractions from the edges of the finite-width AML reducing the amplitude of the AML reflections. Rough seafloor and/or a rough AML surface can also greatly reduce the amplitude of peg-leg multiples because of scattering and destructive interference. Mid-crustal seismic reflection events are observed in the three-dimensional multi-channel seismic dataset acquired over the RIDGE-2000 Integrated Study Site at East Pacific Rise (EPR, cruise MGL0812). Modeling indicates that the mid-crustal seismic reflection reflections are unlikely to arise from peg-leg multiples of the AML reflections, P-to- S converted phases, or scattering due to rough topography, but could probably arise from deeper multiple magma sills. Our results support the identification of Marjanović et al. (Nat Geosci 7(11):825-829, 2014) that a multi-level complex of melt lenses is present beneath the axis of the EPR.

Dependency-dependent interference: NPI interference, agreement attraction, and global pragmatic inferences

PubMed Central

Xiang, Ming; Grove, Julian; Giannakidou, Anastasia

2013-01-01

Previous psycholinguistics studies have shown that when forming a long distance dependency in online processing, the parser sometimes accepts a sentence even though the required grammatical constraints are only partially met. A mechanistic account of how such errors arise sheds light on both the underlying linguistic representations involved and the processing mechanisms that put such representations together. In the current study, we contrast the negative polarity items (NPI) interference effect, as shown by the acceptance of an ungrammatical sentence like “The bills that democratic senators have voted for will ever become law,” with the well-known phenomenon of agreement attraction (“The key to the cabinets are … ”). On the surface, these two types of errors look alike and thereby can be explained as being driven by the same source: similarity based memory interference. However, we argue that the linguistic representations involved in NPI licensing are substantially different from those of subject-verb agreement, and therefore the interference effects in each domain potentially arise from distinct sources. In particular, we show that NPI interference at least partially arises from pragmatic inferences. In a self-paced reading study with an acceptability judgment task, we showed NPI interference was modulated by participants' general pragmatic communicative skills, as quantified by the Autism-Spectrum Quotient (AQ, Baron-Cohen et al., 2001), especially in offline tasks. Participants with more autistic traits were actually less prone to the NPI interference effect than those with fewer autistic traits. This result contrasted with agreement attraction conditions, which were not influenced by individual pragmatic skill differences. We also show that different NPI licensors seem to have distinct interference profiles. We discuss two kinds of interference effects for NPI licensing: memory-retrieval based and pragmatically triggered. PMID:24109468

Twistor-strings and gravity tree amplitudes

NASA Astrophysics Data System (ADS)

Adamo, Tim; Mason, Lionel

2013-04-01

Recently we discussed how Einstein supergravity tree amplitudes might be obtained from the original Witten and Berkovits twistor-string theory when external conformal gravitons are restricted to be Einstein gravitons. Here we obtain a more systematic understanding of the relationship between conformal and Einstein gravity amplitudes in that twistor-string theory. We show that although it does not in general yield Einstein amplitudes, we can nevertheless obtain some partial twistor-string interpretation of the remarkable formulae recently been found by Hodges and generalized to all tree amplitudes by Cachazo and Skinner. The Hodges matrix and its higher degree generalizations encode the world sheet correlators of the twistor string. These matrices control both Einstein amplitudes and those of the conformal gravity arising from the Witten and Berkovits twistor-string. Amplitudes in the latter case arise from products of the diagonal elements of the generalized Hodges matrices and reduced determinants give the former. The reduced determinants arise if the contractions in the worldsheet correlator are restricted to form connected trees at MHV. The (generalized) Hodges matrices arise as weighted Laplacian matrices for the graph of possible contractions in the correlators and the reduced determinants of these weighted Laplacian matrices give the sum of the connected tree contributions by an extension of the matrix-tree theorem.

Cesarean section after abdominal mesh repair for pregnancy-related desmoid tumor: a case report

PubMed Central

Ooi, Sara; Ngo, Harry

2017-01-01

We report the case of a 32-year-old gravida 2 para 1 woman with a background of partially resected desmoid tumor (DT) arising from the previous cesarean section (CS) scar. This case details the management of her DT by surgical resection and mesh repair and second pregnancy following this. Pregnancy-related DTs are a relatively rare entity, and there is a paucity of literature regarding their management during pregnancy. There are only five reported cases of DTs arising from CS scars. To our knowledge, this is the only report to illustrate that subsequent CS is possible after desmoid resection and abdominal mesh repair. It provides evidence that CS can be safely accomplished following abdominal wall reconstructions and further arguments against elective lower segment CS. PMID:28744163

Cesarean section after abdominal mesh repair for pregnancy-related desmoid tumor: a case report.

PubMed

Ooi, Sara; Ngo, Harry

2017-01-01

We report the case of a 32-year-old gravida 2 para 1 woman with a background of partially resected desmoid tumor (DT) arising from the previous cesarean section (CS) scar. This case details the management of her DT by surgical resection and mesh repair and second pregnancy following this. Pregnancy-related DTs are a relatively rare entity, and there is a paucity of literature regarding their management during pregnancy. There are only five reported cases of DTs arising from CS scars. To our knowledge, this is the only report to illustrate that subsequent CS is possible after desmoid resection and abdominal mesh repair. It provides evidence that CS can be safely accomplished following abdominal wall reconstructions and further arguments against elective lower segment CS.

Astrophysical constraints on Planck scale dissipative phenomena.

PubMed

Liberati, Stefano; Maccione, Luca

2014-04-18

The emergence of a classical spacetime from any quantum gravity model is still a subtle and only partially understood issue. If indeed spacetime is arising as some sort of large scale condensate of more fundamental objects, then it is natural to expect that matter, being a collective excitation of the spacetime constituents, will present modified kinematics at sufficiently high energies. We consider here the phenomenology of the dissipative effects necessarily arising in such a picture. Adopting dissipative hydrodynamics as a general framework for the description of the energy exchange between collective excitations and the spacetime fundamental degrees of freedom, we discuss how rates of energy loss for elementary particles can be derived from dispersion relations and used to provide strong constraints on the base of current astrophysical observations of high-energy particles.

Adenocarcinoma of the ethmoid following radiotherapy for bilateral retinoblastoma

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

Rowe, L.D.; Lane, R.; Snow, J.B. Jr.

1980-01-01

Adenocarcinoma of the ethmoid sinus is rare, representing only 4 to 8% of malignancies of the paranasal sinuses. An extraordinary case of papillary adenocarcinoma of the ethmoid sinus arising 30 years following high-dose radiotherapy for bilateral retinoblastoma is presented. Second fatal mesenchymal and epithelial primaries have been described in 8.5% of patients with bilateral retinoblastomas previously treated with radiotherapy; however, papillary adenocarcinoma arising within the paranasal sinuses has not been reported. Aggressive treatment including partial maxillectomy, radical pansinusectomy, radical neck dissection followed by regional radiotherapy and systemic chemotherapy failed to prevent the development of fatal hepatic metastases. The high incidencemore » of second fatal primary neoplasms in patients with bilateral retinoblastomas receiving radiation suggests an innate susceptibility that may add to the risk of radiotherapy.« less

Flow structure in continuous flow electrophoresis chambers

NASA Technical Reports Server (NTRS)

Deiber, J. A.; Saville, D. A.

1982-01-01

There are at least two ways that hydrodynamic processes can limit continiuous flow electrophoresis. One arises from the sensitivity of the flow to small temerature gradients, especially at low flow rates and power levels. This sensitivity can be suppressed, at least in principle, by providing a carefully tailored, stabilizing temperature gradient in the cooling system that surrounds the flow channel. At higher power levels another limitation arises due to a restructuring of the main flow. This restructuring is caused by buoyancy, which is in turn affected by the electro-osmotic crossflow. Approximate solutions to appropriate partial differential equations have been computed by finite difference methods. One set of results is described here to illustrate the strong coupling between the structure of the main (axial) flow and the electro-osmotic flow.

Geometrical and wave optics of paraxial beams.

PubMed

Meron, M; Viccaro, P J; Lin, B

1999-06-01

Most calculational techniques used to evaluate beam propagation are geared towards either fully coherent or fully incoherent beams. The intermediate partial-coherence regime, while in principle known for a long time, has received comparably little attention so far. The resulting shortage of adequate calculational techniques is currently being felt in the realm of x-ray optics where, with the advent of third generation synchrotron light sources, partially coherent beams become increasingly common. The purpose of this paper is to present a calculational approach which, utilizing a "variance matrix" representation of paraxial beams, allows for a straightforward evaluation of wave propagation through an optical system. Being capable of dealing with an arbitrary degree of coherence, this approach covers the whole range from wave to ray optics, in a seamless fashion.

A comparative study of proliferative nodules and lethal melanomas in congenital nevi from children.

PubMed

Yélamos, Oriol; Arva, Nicoleta C; Obregon, Roxana; Yazdan, Pedram; Wagner, Annette; Guitart, Joan; Gerami, Pedram

2015-03-01

Differentiating proliferative nodules (PNs) from melanomas arising in congenital nevi (CN) is a considerable challenge for dermatopathologists. Most of the specimens dermatopathologists assess that deal with this differential diagnosis involve proliferations of melanocytes arising in the dermis. In this study, we compare the clinical, histologic, and molecular findings of these 2 conditions. In our database, we found 22 examples of PNs arising in the dermis of CN and 2 cases of lethal melanomas arising from the dermis/epidermis of CN of children. Importantly, we found that among dermal melanocytic proliferations arising from CN in children, PNs are far more common than lethal melanomas. Clinically, multiplicity of lesions favored a diagnosis of PNs, whereas ulceration was infrequent in PNs compared with lethal melanomas. Histologically, PNs showed several distinct patterns including expansile nodules of epithelioid melanocytes with mitotic counts lower than that seen in the melanomas (1.67 vs. 12.5 mitoses/mm), a small round blue cell pattern often highly mitotically active, neurocristic-like, blue nevus-like, a nevoid melanoma-like pattern, or an undifferentiated spindle cell pattern. The lethal melanomas both featured expansile nodules of epithelioid melanocytes with high mitotic counts (range, 5 to 20 mitoses/mm) and an ulcerated overlying epidermis. At the molecular level, the PNs showed mostly whole chromosomal copy number aberrations, which in some cases were accompanied by rare partial chromosomal aberrations, whereas both lethal melanomas showed highly elevated copy number aberrations involving 6p25 without gains of the long arm of chromosome 6.

Conjugate-gradient preconditioning methods for shift-variant PET image reconstruction.

PubMed

Fessler, J A; Booth, S D

1999-01-01

Gradient-based iterative methods often converge slowly for tomographic image reconstruction and image restoration problems, but can be accelerated by suitable preconditioners. Diagonal preconditioners offer some improvement in convergence rate, but do not incorporate the structure of the Hessian matrices in imaging problems. Circulant preconditioners can provide remarkable acceleration for inverse problems that are approximately shift-invariant, i.e., for those with approximately block-Toeplitz or block-circulant Hessians. However, in applications with nonuniform noise variance, such as arises from Poisson statistics in emission tomography and in quantum-limited optical imaging, the Hessian of the weighted least-squares objective function is quite shift-variant, and circulant preconditioners perform poorly. Additional shift-variance is caused by edge-preserving regularization methods based on nonquadratic penalty functions. This paper describes new preconditioners that approximate more accurately the Hessian matrices of shift-variant imaging problems. Compared to diagonal or circulant preconditioning, the new preconditioners lead to significantly faster convergence rates for the unconstrained conjugate-gradient (CG) iteration. We also propose a new efficient method for the line-search step required by CG methods. Applications to positron emission tomography (PET) illustrate the method.

Sensitivity analysis in practice: providing an uncertainty budget when applying supplement 1 to the GUM

NASA Astrophysics Data System (ADS)

Allard, Alexandre; Fischer, Nicolas

2018-06-01

Sensitivity analysis associated with the evaluation of measurement uncertainty is a very important tool for the metrologist, enabling them to provide an uncertainty budget and to gain a better understanding of the measurand and the underlying measurement process. Using the GUM uncertainty framework, the contribution of an input quantity to the variance of the output quantity is obtained through so-called ‘sensitivity coefficients’. In contrast, such coefficients are no longer computed in cases where a Monte-Carlo method is used. In such a case, supplement 1 to the GUM suggests varying the input quantities one at a time, which is not an efficient method and may provide incorrect contributions to the variance in cases where significant interactions arise. This paper proposes different methods for the elaboration of the uncertainty budget associated with a Monte Carlo method. An application to the mass calibration example described in supplement 1 to the GUM is performed with the corresponding R code for implementation. Finally, guidance is given for choosing a method, including suggestions for a future revision of supplement 1 to the GUM.

Influence of mom and dad: quantitative genetic models for maternal effects and genomic imprinting.

PubMed

Santure, Anna W; Spencer, Hamish G

2006-08-01

The expression of an imprinted gene is dependent on the sex of the parent it was inherited from, and as a result reciprocal heterozygotes may display different phenotypes. In contrast, maternal genetic terms arise when the phenotype of an offspring is influenced by the phenotype of its mother beyond the direct inheritance of alleles. Both maternal effects and imprinting may contribute to resemblance between offspring of the same mother. We demonstrate that two standard quantitative genetic models for deriving breeding values, population variances and covariances between relatives, are not equivalent when maternal genetic effects and imprinting are acting. Maternal and imprinting effects introduce both sex-dependent and generation-dependent effects that result in differences in the way additive and dominance effects are defined for the two approaches. We use a simple example to demonstrate that both imprinting and maternal genetic effects add extra terms to covariances between relatives and that model misspecification may over- or underestimate true covariances or lead to extremely variable parameter estimation. Thus, an understanding of various forms of parental effects is essential in correctly estimating quantitative genetic variance components.

Exploring homogeneity of correlation structures of gene expression datasets within and between etiological disease categories.

PubMed

Jong, Victor L; Novianti, Putri W; Roes, Kit C B; Eijkemans, Marinus J C

2014-12-01

The literature shows that classifiers perform differently across datasets and that correlations within datasets affect the performance of classifiers. The question that arises is whether the correlation structure within datasets differ significantly across diseases. In this study, we evaluated the homogeneity of correlation structures within and between datasets of six etiological disease categories; inflammatory, immune, infectious, degenerative, hereditary and acute myeloid leukemia (AML). We also assessed the effect of filtering; detection call and variance filtering on correlation structures. We downloaded microarray datasets from ArrayExpress for experiments meeting predefined criteria and ended up with 12 datasets for non-cancerous diseases and six for AML. The datasets were preprocessed by a common procedure incorporating platform-specific recommendations and the two filtering methods mentioned above. Homogeneity of correlation matrices between and within datasets of etiological diseases was assessed using the Box's M statistic on permuted samples. We found that correlation structures significantly differ between datasets of the same and/or different etiological disease categories and that variance filtering eliminates more uncorrelated probesets than detection call filtering and thus renders the data highly correlated.

Modeling Menstrual Cycle Length and Variability at the Approach of Menopause Using Hierarchical Change Point Models

PubMed Central

Huang, Xiaobi; Elliott, Michael R.; Harlow, Siobán D.

2013-01-01

SUMMARY As women approach menopause, the patterns of their menstrual cycle lengths change. To study these changes, we need to jointly model both the mean and variability of cycle length. Our proposed model incorporates separate mean and variance change points for each woman and a hierarchical model to link them together, along with regression components to include predictors of menopausal onset such as age at menarche and parity. Additional complexity arises from the fact that the calendar data have substantial missingness due to hormone use, surgery, and failure to report. We integrate multiple imputation and time-to event modeling in a Bayesian estimation framework to deal with different forms of the missingness. Posterior predictive model checks are applied to evaluate the model fit. Our method successfully models patterns of women’s menstrual cycle trajectories throughout their late reproductive life and identifies change points for mean and variability of segment length, providing insight into the menopausal process. More generally, our model points the way toward increasing use of joint mean-variance models to predict health outcomes and better understand disease processes. PMID:24729638

Theory of a general class of dissipative processes.

NASA Technical Reports Server (NTRS)

Hale, J. K.; Lasalle, J. P.; Slemrod, M.

1972-01-01

Development of a theory of periodic processes that is of sufficient generality for being applied to systems defined by partial differential equations (distributed parameter systems) and functional differential equations of the retarded and neutral type (hereditary systems), as well as to systems arising in the theory of elasticity. In particular, the attempt is made to develop a meaningful general theory of dissipative periodic systems with a wide range of applications.

Schwanomma From Cervical Sympathetic Chain Ganglion - A Rare Presentation.

PubMed

Asma, A Affee; Kannah, E

2015-10-01

Schwanommas arising from cervical sympathetic chain are tumours that are rare in occurrence. These lesions are usually difficult to differentiate from a vagal schwanomma and a carotid body tumour during the initial workup. In this report, a rarely seen huge cervical sympathetic chain schwanomma case with partial Horner's syndrome is being presented in detail, which to our known knowledge, is one of the few cases reported in literature.

Modelling the aggregation process of cellular slime mold by the chemical attraction.

PubMed

Atangana, Abdon; Vermeulen, P D

2014-01-01

We put into exercise a comparatively innovative analytical modus operandi, the homotopy decomposition method (HDM), for solving a system of nonlinear partial differential equations arising in an attractor one-dimensional Keller-Segel dynamics system. Numerical solutions are given and some properties show evidence of biologically practical reliance on the parameter values. The reliability of HDM and the reduction in computations give HDM a wider applicability.

LORENE: Spectral methods differential equations solver

NASA Astrophysics Data System (ADS)

Gourgoulhon, Eric; Grandclément, Philippe; Marck, Jean-Alain; Novak, Jérôme; Taniguchi, Keisuke

2016-08-01

LORENE (Langage Objet pour la RElativité NumériquE) solves various problems arising in numerical relativity, and more generally in computational astrophysics. It is a set of C++ classes and provides tools to solve partial differential equations by means of multi-domain spectral methods. LORENE classes implement basic structures such as arrays and matrices, but also abstract mathematical objects, such as tensors, and astrophysical objects, such as stars and black holes.

Geometric morphometrics analysis of the hind wing of leaf beetles: proximal and distal parts are separate modules.

PubMed

Ren, Jing; Bai, Ming; Yang, Xing-Ke; Zhang, Run-Zhi; Ge, Si-Qin

2017-01-01

The success of beetles is mainly attributed to the possibility to hide the hindwings under the sclerotised elytra. The acquisition of the transverse folding function of the hind wing is an important event in the evolutionary history of beetles. In this study, the morphological and functional variances in the hind wings of 94 leaf beetle species (Coleoptera: Chrysomelinae) is explored using geometric morphometrics based on 36 landmarks. Principal component analysis and Canonical variate analysis indicate that changes of apical area, anal area, and middle area are three useful phylogenetic features at a subtribe level of leaf beetles. Variances of the apical area are the most obvious, which strongly influence the entire venation variance. Partial least squares analysis indicates that the proximal and distal parts of hind wings are weakly associated. Modularity tests confirm that the proximal and distal compartments of hind wings are separate modules. It is deduced that for leaf beetles, or even other beetles, the hind wing possibly exhibits significant functional divergences that occurred during the evolution of transverse folding that resulted in the proximal and distal compartments of hind wings evolving into separate functional modules.

Kriging analysis of mean annual precipitation, Powder River Basin, Montana and Wyoming

USGS Publications Warehouse

Karlinger, M.R.; Skrivan, James A.

1981-01-01

Kriging is a statistical estimation technique for regionalized variables which exhibit an autocorrelation structure. Such structure can be described by a semi-variogram of the observed data. The kriging estimate at any point is a weighted average of the data, where the weights are determined using the semi-variogram and an assumed drift, or lack of drift, in the data. Block, or areal, estimates can also be calculated. The kriging algorithm, based on unbiased and minimum-variance estimates, involves a linear system of equations to calculate the weights. Kriging variances can then be used to give confidence intervals of the resulting estimates. Mean annual precipitation in the Powder River basin, Montana and Wyoming, is an important variable when considering restoration of coal-strip-mining lands of the region. Two kriging analyses involving data at 60 stations were made--one assuming no drift in precipitation, and one a partial quadratic drift simulating orographic effects. Contour maps of estimates of mean annual precipitation were similar for both analyses, as were the corresponding contours of kriging variances. Block estimates of mean annual precipitation were made for two subbasins. Runoff estimates were 1-2 percent of the kriged block estimates. (USGS)

Optimism, well-being, depressive symptoms, and perceived physical health: a study among Stroke survivors.

PubMed

Shifren, Kim; Anzaldi, Kristen

2018-01-01

The investigation of the relation of positive personality characteristics to mental and physical health among Stroke survivors has been a neglected area of research. The purpose of this study was to examine the relationship between optimism, well-being, depressive symptoms, and perceived physical health among Stroke survivors. It was hypothesized that Stroke survivors' optimism would explain variance in their physical health above and beyond the variance explained by demographic variables, diagnostic variables, and mental health. One hundred seventy-six Stroke survivors (97 females, 79 males) completed the Revised Life Orientation Test, the Center for Epidemiological Studies Depression Scale, two items on perceived physical health from the 36-item Short Form of the Medical Outcomes study, and the Identity scale of the Illness Perception Questionnaire. Pearson correlations, hierarchical regression analyses, and the PROCESS approach to determining mediators were used to assess hypothesized relations between variables. Stroke survivors' level of optimism explained additional variance in overall health in regression models controlling for demographic and diagnostic variables, and mental health. Analyses revealed that optimism played a partial mediator role between mental health (well-being, depressive symptoms and total score on CES-D) variables and overall health.

Partially resistant Cucurbita pepo showed late onset of the Zucchini yellow mosaic virus infection due to rapid activation of defense mechanisms as compared to susceptible cultivar

PubMed Central

Nováková, Slavomíra; Flores-Ramírez, Gabriela; Glasa, Miroslav; Danchenko, Maksym; Fiala, Roderik; Skultety, Ludovit

2015-01-01

Zucchini yellow mosaic virus (ZYMV) is an emerging viral pathogen in cucurbit-growing areas wordwide. Infection causes significant yield losses in several species of the family Cucurbitaceae. To identify proteins potentially involved with resistance toward infection by the severe ZYMV-H isolate, two Cucurbita pepo cultivars (Zelena susceptible and Jaguar partially resistant) were analyzed using a two-dimensional gel electrophoresis-based proteomic approach. Initial symptoms on leaves (clearing veins) developed 6–7 days post-inoculation (dpi) in the susceptible C. pepo cv. Zelena. In contrast, similar symptoms appeared on the leaves of partially resistant C. pepo cv. Jaguar only after 15 dpi. This finding was confirmed by immune-blot analysis which showed higher levels of viral proteins at 6 dpi in the susceptible cultivar. Leaf proteome analyses revealed 28 and 31 spots differentially abundant between cultivars at 6 and 15 dpi, respectively. The variance early in infection can be attributed to a rapid activation of proteins involved with redox homeostasis in the partially resistant cultivar. Changes in the proteome of the susceptible cultivar are related to the cytoskeleton and photosynthesis. PMID:25972878

Refractory pulse counting processes in stochastic neural computers.

PubMed

McNeill, Dean K; Card, Howard C

2005-03-01

This letter quantitiatively investigates the effect of a temporary refractory period or dead time in the ability of a stochastic Bernoulli processor to record subsequent pulse events, following the arrival of a pulse. These effects can arise in either the input detectors of a stochastic neural network or in subsequent processing. A transient period is observed, which increases with both the dead time and the Bernoulli probability of the dead-time free system, during which the system reaches equilibrium. Unless the Bernoulli probability is small compared to the inverse of the dead time, the mean and variance of the pulse count distributions are both appreciably reduced.

Mean-Reverting Portfolio With Budget Constraint

NASA Astrophysics Data System (ADS)

Zhao, Ziping; Palomar, Daniel P.

2018-05-01

This paper considers the mean-reverting portfolio design problem arising from statistical arbitrage in the financial markets. We first propose a general problem formulation aimed at finding a portfolio of underlying component assets by optimizing a mean-reversion criterion characterizing the mean-reversion strength, taking into consideration the variance of the portfolio and an investment budget constraint. Then several specific problems are considered based on the general formulation, and efficient algorithms are proposed. Numerical results on both synthetic and market data show that our proposed mean-reverting portfolio design methods can generate consistent profits and outperform the traditional design methods and the benchmark methods in the literature.

Social information processing in children: specific relations to anxiety, depression, and affect.

PubMed

Luebbe, Aaron M; Bell, Debora J; Allwood, Maureen A; Swenson, Lance P; Early, Martha C

2010-01-01

Two studies examined shared and unique relations of social information processing (SIP) to youth's anxious and depressive symptoms. Whether SIP added unique variance over and above trait affect in predicting internalizing symptoms was also examined. In Study 1, 215 youth (ages 8-13) completed symptom measures of anxiety and depression and a vignette-based interview measure of SIP. Anxiety and depression were each related to a more negative information-processing style. Only depression was uniquely related to a less positive information processing style. In Study 2, 127 youth (ages 10-13) completed measures of anxiety, depression, SIP, and trait affect. SIP's relations to internalizing symptoms were replicated. Over and above negative affect, negative SIP predicted both anxiety and depression. Low positive SIP added variance over and above positive affect in predicting only depression. Finally, SIP functioning partially mediated the relations of affect to internalizing symptoms.

A Modular Mind? A Test Using Individual Data from Seven Primate Species

PubMed Central

Amici, Federica; Barney, Bradley; Johnson, Valen E.; Call, Josep; Aureli, Filippo

2012-01-01

It has long been debated whether the mind consists of specialized and independently evolving modules, or whether and to what extent a general factor accounts for the variance in performance across different cognitive domains. In this study, we used a hierarchical Bayesian model to re-analyse individual level data collected on seven primate species (chimpanzees, bonobos, orangutans, gorillas, spider monkeys, brown capuchin monkeys and long-tailed macaques) across 17 tasks within four domains (inhibition, memory, transposition and support). Our modelling approach evidenced the existence of both a domain-specific factor and a species factor, each accounting for the same amount (17%) of the observed variance. In contrast, inter-individual differences played a minimal role. These results support the hypothesis that the mind of primates is (at least partially) modular, with domain-specific cognitive skills undergoing different evolutionary pressures in different species in response to specific ecological and social demands. PMID:23284816

Correlations for Adolescent Resilience Scale with big five personality traits.

PubMed

Nakaya, Motoyuki; Oshio, Atsushi; Kaneko, Hitoshi

2006-06-01

Currently, individuals tend to encounter many unavoidable, painful events and hardships in the process of growth and development. To lead one's life adapting to these social conditions, it is necessary to maintain one's mental health even while experiencing challenging events; in other words, resilience is required. This study of 130 undergraduates focused on the Adolescent Resilience Scale which assesses capacity for successful adaptation despite challenging or threatening circumstances and examined correlations with scores on the Big Five Personality Inventory. A significant negative correlation of -.59 (p<.001) was noted for scores on the Adolescent Resilience Scale and the Neuroticism dimension of the Big Five Personality Inventory, accounting for 35% of the variance, and positive values with the Extraversion, Openness, and Conscientiousness dimensions (rs= .37, .40, .48, accounting for 14, 16, and 18% of the variance, respectively. Personalities of adolescents who have psychological traits leading to resilience may be partially predicted using these results.

Different slopes for different folks: alpha and delta EEG power predict subsequent video game learning rate and improvements in cognitive control tasks.

PubMed

Mathewson, Kyle E; Basak, Chandramallika; Maclin, Edward L; Low, Kathy A; Boot, Walter R; Kramer, Arthur F; Fabiani, Monica; Gratton, Gabriele

2012-12-01

We hypothesized that control processes, as measured using electrophysiological (EEG) variables, influence the rate of learning of complex tasks. Specifically, we measured alpha power, event-related spectral perturbations (ERSPs), and event-related brain potentials during early training of the Space Fortress task, and correlated these measures with subsequent learning rate and performance in transfer tasks. Once initial score was partialled out, the best predictors were frontal alpha power and alpha and delta ERSPs, but not P300. By combining these predictors, we could explain about 50% of the learning rate variance and 10%-20% of the variance in transfer to other tasks using only pretraining EEG measures. Thus, control processes, as indexed by alpha and delta EEG oscillations, can predict learning and skill improvements. The results are of potential use to optimize training regimes. Copyright © 2012 Society for Psychophysiological Research.

Optimal phase estimation with arbitrary a priori knowledge

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

Demkowicz-Dobrzanski, Rafal

2011-06-15

The optimal-phase estimation strategy is derived when partial a priori knowledge on the estimated phase is available. The solution is found with the help of the most famous result from the entanglement theory: the positive partial transpose criterion. The structure of the optimal measurements, estimators, and the optimal probe states is analyzed. This Rapid Communication provides a unified framework bridging the gap in the literature on the subject which until now dealt almost exclusively with two extreme cases: almost perfect knowledge (local approach based on Fisher information) and no a priori knowledge (global approach based on covariant measurements). Special attentionmore » is paid to a natural a priori probability distribution arising from a diffusion process.« less

An ansatz for solving nonlinear partial differential equations in mathematical physics.

PubMed

Akbar, M Ali; Ali, Norhashidah Hj Mohd

2016-01-01

In this article, we introduce an ansatz involving exact traveling wave solutions to nonlinear partial differential equations. To obtain wave solutions using direct method, the choice of an appropriate ansatz is of great importance. We apply this ansatz to examine new and further general traveling wave solutions to the (1+1)-dimensional modified Benjamin-Bona-Mahony equation. Abundant traveling wave solutions are derived including solitons, singular solitons, periodic solutions and general solitary wave solutions. The solutions emphasize the nobility of this ansatz in providing distinct solutions to various tangible phenomena in nonlinear science and engineering. The ansatz could be more efficient tool to deal with higher dimensional nonlinear evolution equations which frequently arise in many real world physical problems.

Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules: Preprint

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

Silverman, Timothy J.; Deceglie, Michael G.; Sun, Xingshu

2015-09-02

Photovoltaic cells can be damaged by reverse bias stress, which arises during service when a monolithically integrated thin-film module is partially shaded. We introduce a model for describing a module's internal thermal and electrical state, which cannot normally be measured. Using this model and experimental measurements, we present several results with relevance for reliability testing and module engineering: Modules with a small breakdown voltage experience less stress than those with a large breakdown voltage, with some exceptions for modules having light-enhanced reverse breakdown. Masks leaving a small part of the masked cells illuminated can lead to very high temperature andmore » current density compared to masks covering entire cells.« less

Thermal and Electrical Effects of Partial Shade in Monolithic Thin-Film Photovoltaic Modules

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

Silverman, Timothy J.; Deceglie, Michael G.; Sun, Xingshu

2015-06-14

Photovoltaic cells can be damaged by reverse bias stress, which arises during service when a monolithically integrated thin-film module is partially shaded. We introduce a model for describing a module's internal thermal and electrical state, which cannot normally be measured. Using this model and experimental measurements, we present several results with relevance for reliability testing and module engineering: Modules with a small breakdown voltage experience less stress than those with a large breakdown voltage, with some exceptions for modules having light-enhanced reverse breakdown. Masks leaving a small part of the masked cells illuminated can lead to very high temperature andmore » current density compared to masks covering entire cells.« less

Case of telangiectatic/inflammatory hepatocellular adenoma arising in a patient with primary sclerosing cholangitis.

PubMed

Maylee, Hsu; Harada, Kenichi; Igarashi, Saya; Tohda, Gen; Yamamoto, Makoto; Ren, Xiang Shan; Osawa, Takeshi; Hasegawa, Yasuhiro; Takahashi, Norio; Nakanuma, Yasuni

2012-06-01

Hepatocellular adenomas (HCA) have been recently identified as a heterogeneous group, differing based on genotypic as well as morphological characteristics. HCA are most frequently found in women on oral contraception. A type of HCA, inflammatory HCA, is also known as telangiectatic HCA and was previously referred to as telangiectatic focal nodular hyperplasia. We present the first case of HCA arising from the liver with primary sclerosing cholangitis (PSC). This case is a 30-year-old man with a past medical history of PSC, ulcerative colitis and diabetes mellitus. A routine ultrasonography for PSC detected the gradually enlarged intrahepatic mass. Liver biopsy could reveal the diagnosis of telangiectatic/ inflammatory HCA by morphological and immunohistochemical analyses. Partial hepatectomy was performed and the resected liver was pathologically diagnosed as the telangiectatic/inflammatory HCA arising in PSC. This is the first case report of such an association and here we review the current developments and published work of this rare tumor and the association with an activated inflammatory related tumorogenic pathway and PSC. © 2012 The Japan Society of Hepatology.

Prediction of the Pharmacokinetic Parameters of Triptolide in Rats Based on Endogenous Molecules in Pre-Dose Baseline Serum

PubMed Central

Aa, Jiye; Zheng, Tian; Shi, Jian; Li, Mengjie; Wang, Xinwen; Zhao, Chunyan; Xiao, Wenjing; Yu, Xiaoyi; Sun, Runbin; Gu, Rongrong; Zhou, Jun; Wu, Liang; Hao, Gang; Zhu, Xuanxuan; Wang, Guangji

2012-01-01

Background Individual variances usually affect drug metabolism and disposition, and hence result in either ineffectiveness or toxicity of a drug. In addition to genetic polymorphism, the multiple confounding factors of lifestyles, such as dietary preferences, contribute partially to individual variances. However, the difficulty of quantifying individual diversity greatly challenges the realization of individualized drug therapy. This study aims at quantitative evaluating the association between individual variances and the pharmacokinetics. Methodology/Principal Findings Molecules in pre-dose baseline serum were profiled using gas chromatography mass spectrometry to represent the individual variances of the model rats provided with high fat diets (HFD), routine chows and calorie restricted (CR) chows. Triptolide and its metabolites were determined using high performance liquid chromatography mass spectrometry. Metabonomic and pharmacokinetic data revealed that rats treated with the varied diets had distinctly different metabolic patterns and showed differential Cmax values, AUC and drug metabolism after oral administration of triptolide. Rats with fatty chows had the lowest Cmax and AUC values and the highest percentage of triptolide metabolic transformation, while rats with CR chows had the highest Cmax and AUC values and the least percentage of triptolide transformation. Multivariate linear regression revealed that in baseline serum, the concentrations of creatinine and glutamic acid, which is the precursor of GSH, were linearly negatively correlated to Cmax and AUC values. The glutamic acid and creatinine in baseline serum were suggested as the potential markers to represent individual diversity and as predictors of the disposal and pharmacokinetics of triptolide. Conclusions/Significance These results highlight the robust potential of metabonomics in characterizing individual variances and identifying relevant markers that have the potential to facilitate individualized drug therapy. PMID:22912866

On Flood Frequency in Urban Areas under Changing Conditions and Implications on Stormwater Infrastructure Planning and Design

NASA Astrophysics Data System (ADS)

Norouzi, A.; Habibi, H.; Nazari, B.; Noh, S.; Seo, D. J.; Zhang, Y.

2016-12-01

With urbanization and climate change, many areas in the US and abroad face increasing threats of flash flooding. Due to nonstationarities arising from changes in land cover and climate, however, it is not readily possible to project how such changes may modify flood frequency. In this work, we describe a simple spatial stochastic model for rainfall-to-areal runoff in urban areas, evaluate climatological mean and variance of mean areal runoff (MAR) over a range of catchment scale, translate them into runoff frequency, which is used as a proxy for flood frequency, and assess its sensitivity to precipitation, imperviousness and soil, and their changes as a function of catchment scale and magnitude of precipitation. The findings indicate that, due to large sensitivity of frequency of MAR to multiple hydrometeorological and physiographic factors, estimation of flood frequency for urban catchments is inherently more uncertain. The approach used in this work is useful in developing bounds for flood frequencies in urban areas under nonstationary conditions arising from urbanization and climate change.

Impact of multicollinearity on small sample hydrologic regression models

NASA Astrophysics Data System (ADS)

Kroll, Charles N.; Song, Peter

2013-06-01

Often hydrologic regression models are developed with ordinary least squares (OLS) procedures. The use of OLS with highly correlated explanatory variables produces multicollinearity, which creates highly sensitive parameter estimators with inflated variances and improper model selection. It is not clear how to best address multicollinearity in hydrologic regression models. Here a Monte Carlo simulation is developed to compare four techniques to address multicollinearity: OLS, OLS with variance inflation factor screening (VIF), principal component regression (PCR), and partial least squares regression (PLS). The performance of these four techniques was observed for varying sample sizes, correlation coefficients between the explanatory variables, and model error variances consistent with hydrologic regional regression models. The negative effects of multicollinearity are magnified at smaller sample sizes, higher correlations between the variables, and larger model error variances (smaller R2). The Monte Carlo simulation indicates that if the true model is known, multicollinearity is present, and the estimation and statistical testing of regression parameters are of interest, then PCR or PLS should be employed. If the model is unknown, or if the interest is solely on model predictions, is it recommended that OLS be employed since using more complicated techniques did not produce any improvement in model performance. A leave-one-out cross-validation case study was also performed using low-streamflow data sets from the eastern United States. Results indicate that OLS with stepwise selection generally produces models across study regions with varying levels of multicollinearity that are as good as biased regression techniques such as PCR and PLS.

A multiple-objective optimal exploration strategy

USGS Publications Warehouse

Christakos, G.; Olea, R.A.

1988-01-01

Exploration for natural resources is accomplished through partial sampling of extensive domains. Such imperfect knowledge is subject to sampling error. Complex systems of equations resulting from modelling based on the theory of correlated random fields are reduced to simple analytical expressions providing global indices of estimation variance. The indices are utilized by multiple objective decision criteria to find the best sampling strategies. The approach is not limited by geometric nature of the sampling, covers a wide range in spatial continuity and leads to a step-by-step procedure. ?? 1988.

Oral and Cutaneous Lymphomas other than Mycosis Fungoides and Sézary Syndrome in a Mexican Cohort: Recategorization and Evaluation of International Geographical Disparities

PubMed Central

Hernández-Salazar, Amparo; García-Vera, Jorge Andrés; Charli-Joseph, Yann; Ortiz-Pedroza, Guadalupe; Méndez-Flores, Silvia; Orozco-Topete, Rocío; Morales-Leyte, Ana Lilia; Domínguez-Cherit, Judith; Lome-Maldonado, Carmen

2017-01-01

Background: Nonmycosis fungoides/Sézary syndrome (non-MF/SS) primary cutaneous lymphomas (PCL) are currently categorized under the 2005-World Health Organization/European Organization for Research and Treatment of Cancer (WHO-EORTC) classification for PCL. These differ in behavior from secondary cutaneous lymphomas (SCL) and to lymphomas limited to the oral cavity (primary oral lymphomas [POL]) both categorized under the 2016-WHO classification for lymphoid neoplasms. Aims: This study aims to report the first series of non-MF/SS PCL, SCL, and POL in a Mexican cohort, examine the applicability of current classification systems and compare our findings with those from foreign cohorts. Materials and Methods: Eighteen non-MF/SS PCL, four SCL, and two POL with available tissue for morphology and immunophenotypic assessment were reclassified according to the 2005-WHO/EORTC and 2016-WHO classifications. Results: Non-MF/SS PCLs were primarily of T-cell origin (61%) where CD30+ lymphoproliferative disorders predominated, followed by Epstein–Barr virus-induced lymphomas, and peripheral T-cell lymphomas, not otherwise specified. Primary cutaneous B-cell lymphomas (BCL) were primarily of follicle center cell origin followed by postgerminal lymphomas of the diffuse large BCL variety. Conclusions: Most non-MF/SS PCL, SCL, and POL can be adequately categorized according to the 2005-WHO/EORTC and 2016-WHO classification systems, even when dealing with clinically atypical cases. The relative frequencies in our cohort hold closer similarities to Asian registries than from those of Europe/USA, supporting the concept of individual and/or racial susceptibility, and the notion of geographical variances in the rate of lymphomas. In particular, such disparity may arise from viral-induced lymphomas which might show partial geographical restriction. PMID:28400635

View of a standard tool kit left on the ISS

NASA Image and Video Library

2000-09-17

S106-E-5259 (17 September 2000) --- Tools that look much like those that you might find in any residential garage are being left onboard the International Space Station (ISS) for its future residents. Holding this set is astronaut Richard A. Mastracchio, partially out of frame. As any "handy person" will tell you, a variety of basic tools are a life-saver when any one of a number of contingencies arise.

Schwanomma From Cervical Sympathetic Chain Ganglion – A Rare Presentation

PubMed Central

Asma, A. Affee

2015-01-01

Schwanommas arising from cervical sympathetic chain are tumours that are rare in occurrence. These lesions are usually difficult to differentiate from a vagal schwanomma and a carotid body tumour during the initial workup. In this report, a rarely seen huge cervical sympathetic chain schwanomma case with partial Horner’s syndrome is being presented in detail, which to our known knowledge, is one of the few cases reported in literature. PMID:26557566

Radiation Diffusion:. AN Overview of Physical and Numerical Concepts

NASA Astrophysics Data System (ADS)

Graziani, Frank

2005-12-01

An overview of the physical and mathematical foundations of radiation transport is given. Emphasis is placed on how the diffusion approximation and its transport corrections arise. An overview of the numerical handling of radiation diffusion coupled to matter is also given. Discussions center on partial temperature and grey methods with comments concerning fully implicit methods. In addition finite difference, finite element and Pert representations of the div-grad operator is also discussed

Auto-Bäcklund transformations for a matrix partial differential equation

NASA Astrophysics Data System (ADS)

Gordoa, P. R.; Pickering, A.

2018-07-01

We derive auto-Bäcklund transformations, analogous to those of the matrix second Painlevé equation, for a matrix partial differential equation. We also then use these auto-Bäcklund transformations to derive matrix equations involving shifts in a discrete variable, a process analogous to the use of the auto-Bäcklund transformations of the matrix second Painlevé equation to derive a discrete matrix first Painlevé equation. The equations thus derived then include amongst other examples a semidiscrete matrix equation which can be considered to be an extension of this discrete matrix first Painlevé equation. The application of this technique to the auto-Bäcklund transformations of the scalar case of our partial differential equation has not been considered before, and so the results obtained here in this scalar case are also new. Other equations obtained here using this technique include a scalar semidiscrete equation which arises in the case of the second Painlevé equation, and which does not seem to have been thus derived previously.

Getting the story straight. The press and "partial-birth abortion".

PubMed

Farmer, A

2000-06-01

This paper discusses the controversy of the banning of ¿partial-birth abortion¿ in the state of Nebraska. This controversy arises as a result of how several major news sources described the Nebraska statute--that is, as a pre-viability abortion ban, and not a ban on late-term abortion procedures. This issue did not only occur in Nebraska, but also in Michigan when abortion opponents simultaneously initiated a publicity scheme to mislead the public into believing the ban was about ¿gruesome¿ late-term procedures. The deceptive term ¿partial-birth abortion¿, also seemed to suggest abortions performed on viable fetuses and the language describing the ban was confusing and slippery. In response to this controversy, Janet Benshoof, the president of the Center for Reproductive Law and Policy (CRLP) immediately made a statement to counteract the allegation imposed by abortion opponents. Also, CRLP Communications Deputy Director Margie Kelly spends a considerable amount of time informing the press of the extreme measures of the laws.

Single- and multiple-pulse noncoherent detection statistics associated with partially developed speckle.

PubMed

Osche, G R

2000-08-20

Single- and multiple-pulse detection statistics are presented for aperture-averaged direct detection optical receivers operating against partially developed speckle fields. A partially developed speckle field arises when the probability density function of the received intensity does not follow negative exponential statistics. The case of interest here is the target surface that exhibits diffuse as well as specular components in the scattered radiation. An approximate expression is derived for the integrated intensity at the aperture, which leads to single- and multiple-pulse discrete probability density functions for the case of a Poisson signal in Poisson noise with an additive coherent component. In the absence of noise, the single-pulse discrete density function is shown to reduce to a generalized negative binomial distribution. The radar concept of integration loss is discussed in the context of direct detection optical systems where it is shown that, given an appropriate set of system parameters, multiple-pulse processing can be more efficient than single-pulse processing over a finite range of the integration parameter n.

Partially linear mixed-effects joint models for skewed and missing longitudinal competing risks outcomes.

PubMed

Lu, Tao; Lu, Minggen; Wang, Min; Zhang, Jun; Dong, Guang-Hui; Xu, Yong

2017-12-18

Longitudinal competing risks data frequently arise in clinical studies. Skewness and missingness are commonly observed for these data in practice. However, most joint models do not account for these data features. In this article, we propose partially linear mixed-effects joint models to analyze skew longitudinal competing risks data with missingness. In particular, to account for skewness, we replace the commonly assumed symmetric distributions by asymmetric distribution for model errors. To deal with missingness, we employ an informative missing data model. The joint models that couple the partially linear mixed-effects model for the longitudinal process, the cause-specific proportional hazard model for competing risks process and missing data process are developed. To estimate the parameters in the joint models, we propose a fully Bayesian approach based on the joint likelihood. To illustrate the proposed model and method, we implement them to an AIDS clinical study. Some interesting findings are reported. We also conduct simulation studies to validate the proposed method.

Noisy covariance matrices and portfolio optimization

NASA Astrophysics Data System (ADS)

Pafka, S.; Kondor, I.

2002-05-01

According to recent findings [#!bouchaud!#,#!stanley!#], empirical covariance matrices deduced from financial return series contain such a high amount of noise that, apart from a few large eigenvalues and the corresponding eigenvectors, their structure can essentially be regarded as random. In [#!bouchaud!#], e.g., it is reported that about 94% of the spectrum of these matrices can be fitted by that of a random matrix drawn from an appropriately chosen ensemble. In view of the fundamental role of covariance matrices in the theory of portfolio optimization as well as in industry-wide risk management practices, we analyze the possible implications of this effect. Simulation experiments with matrices having a structure such as described in [#!bouchaud!#,#!stanley!#] lead us to the conclusion that in the context of the classical portfolio problem (minimizing the portfolio variance under linear constraints) noise has relatively little effect. To leading order the solutions are determined by the stable, large eigenvalues, and the displacement of the solution (measured in variance) due to noise is rather small: depending on the size of the portfolio and on the length of the time series, it is of the order of 5 to 15%. The picture is completely different, however, if we attempt to minimize the variance under non-linear constraints, like those that arise e.g. in the problem of margin accounts or in international capital adequacy regulation. In these problems the presence of noise leads to a serious instability and a high degree of degeneracy of the solutions.

Final Report, DE-FG01-06ER25718 Domain Decomposition and Parallel Computing

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

Widlund, Olof B.

2015-06-09

The goal of this project is to develop and improve domain decomposition algorithms for a variety of partial differential equations such as those of linear elasticity and electro-magnetics.These iterative methods are designed for massively parallel computing systems and allow the fast solution of the very large systems of algebraic equations that arise in large scale and complicated simulations. A special emphasis is placed on problems arising from Maxwell's equation. The approximate solvers, the preconditioners, are combined with the conjugate gradient method and must always include a solver of a coarse model in order to have a performance which is independentmore » of the number of processors used in the computer simulation. A recent development allows for an adaptive construction of this coarse component of the preconditioner.« less

An Inverse Problem for a Class of Conditional Probability Measure-Dependent Evolution Equations

PubMed Central

Mirzaev, Inom; Byrne, Erin C.; Bortz, David M.

2016-01-01

We investigate the inverse problem of identifying a conditional probability measure in measure-dependent evolution equations arising in size-structured population modeling. We formulate the inverse problem as a least squares problem for the probability measure estimation. Using the Prohorov metric framework, we prove existence and consistency of the least squares estimates and outline a discretization scheme for approximating a conditional probability measure. For this scheme, we prove general method stability. The work is motivated by Partial Differential Equation (PDE) models of flocculation for which the shape of the post-fragmentation conditional probability measure greatly impacts the solution dynamics. To illustrate our methodology, we apply the theory to a particular PDE model that arises in the study of population dynamics for flocculating bacterial aggregates in suspension, and provide numerical evidence for the utility of the approach. PMID:28316360

Optimal configuration of partial Mueller matrix polarimeter for measuring the ellipsometric parameters in the presence of Poisson shot noise and Gaussian noise

NASA Astrophysics Data System (ADS)

Quan, Naicheng; Zhang, Chunmin; Mu, Tingkui

2018-05-01

We address the optimal configuration of a partial Mueller matrix polarimeter used to determine the ellipsometric parameters in the presence of additive Gaussian noise and signal-dependent shot noise. The numerical results show that, for the PSG/PSA consisting of a variable retarder and a fixed polarizer, the detection process immune to these two types of noise can be optimally composed by 121.2° retardation with a pair of azimuths ±71.34° and a 144.48° retardation with a pair of azimuths ±31.56° for four Mueller matrix elements measurement. Compared with the existing configurations, the configuration presented in this paper can effectively decrease the measurement variance and thus statistically improve the measurement precision of the ellipsometric parameters.

Fit Analysis of Different Framework Fabrication Techniques for Implant-Supported Partial Prostheses.

PubMed

Spazzin, Aloísio Oro; Bacchi, Atais; Trevisani, Alexandre; Farina, Ana Paula; Dos Santos, Mateus Bertolini

2016-01-01

This study evaluated the vertical misfit of implant-supported frameworks made using different techniques to obtain passive fit. Thirty three-unit fixed partial dentures were fabricated in cobalt-chromium alloy (n = 10) using three fabrication methods: one-piece casting, framework cemented on prepared abutments, and laser welding. The vertical misfit between the frameworks and the abutments was evaluated with an optical microscope using the single-screw test. Data were analyzed using one-way analysis of variance and Tukey test (α = .05). The one-piece casted frameworks presented significantly higher vertical misfit values than those found for framework cemented on prepared abutments and laser welding techniques (P < .001 and P < .003, respectively). Laser welding and framework cemented on prepared abutments are effective techniques to improve the adaptation of three-unit implant-supported prostheses. These techniques presented similar fit.

Segregation analysis of apolipoproteins A-1 and B-100 measured before and after an exercise training program: the HERITAGE Family Study.

PubMed

An, P; Rice, T; Gagnon, J; Borecki, I B; Bergeron, J; Després, J P; Leon, A S; Skinner, J S; Wilmore, J H; Bouchard, C; Rao, D C

2000-03-01

Complex segregation analyses of apolipoproteins (apo) A-1 and B-100 were performed in a sample of 520 individuals from 99 white families who participated in the HERITAGE Family Study. In these sedentary families, plasma apo A-1 and B-100 concentrations were measured before and after a 20-week endurance exercise training program. Baseline apo A-1 and B-100 were adjusted for the effects of age (age-adjusted baseline apo A-1 and B-100) and for the effects of age and BMI (age-BMI-adjusted baseline apo A-1 and B-100). The change in response to training was computed as a simple Delta (posttraining minus baseline) and was adjusted for age and the baseline (age-baseline-adjusted apo A-1 and B-100 responses to training). In the present study, a major gene could not be inferred for baseline apo A-1. Rather, we found a major effect along with a multifactorial effect accounting for 8% to 9% and 51% to 56% of the variance, respectively. In addition, no clear evidence supported a major-gene effect for its response to training, whereas the transmission of a major effect from parents to offspring was ambiguous, ie, genetic in nature or familial environmental in origin. The major effect accounted for 15% of the variance, with an additional 21% and 58% of the variance being accounted for by a multifactorial effect in parents and offspring, respectively. It is interesting to have obtained evidence of a putative recessive major locus for baseline apo B-100, which accounted for 50% to 56% of the variance, with an additional 25% to 29% of the variance due to a multifactorial effect. In contrast, no major effect for its response to training was identified, although a multifactorial effect was found that accounted for 27% of the variance. The novel findings arising from the present study are summarized as follows. Baseline apo A-1 and its response to training were influenced by a major effect and a multifactorial effect. Baseline apo B-100 was influenced by a putative major recessive gene with a multifactorial component, but its response to training was influenced solely by a multifactorial component in these sedentary families.

Algorithm refinement for stochastic partial differential equations: II. Correlated systems

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

Alexander, Francis J.; Garcia, Alejandro L.; Tartakovsky, Daniel M.

2005-08-10

We analyze a hybrid particle/continuum algorithm for a hydrodynamic system with long ranged correlations. Specifically, we consider the so-called train model for viscous transport in gases, which is based on a generalization of the random walk process for the diffusion of momentum. This discrete model is coupled with its continuous counterpart, given by a pair of stochastic partial differential equations. At the interface between the particle and continuum computations the coupling is by flux matching, giving exact mass and momentum conservation. This methodology is an extension of our stochastic Algorithm Refinement (AR) hybrid for simple diffusion [F. Alexander, A. Garcia,more » D. Tartakovsky, Algorithm refinement for stochastic partial differential equations: I. Linear diffusion, J. Comput. Phys. 182 (2002) 47-66]. Results from a variety of numerical experiments are presented for steady-state scenarios. In all cases the mean and variance of density and velocity are captured correctly by the stochastic hybrid algorithm. For a non-stochastic version (i.e., using only deterministic continuum fluxes) the long-range correlations of velocity fluctuations are qualitatively preserved but at reduced magnitude.« less

Quantum scattering problem without partial-wave analysis

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

Melezhik, V. S., E-mail: melezhik@theor.jinr.ru

2013-02-15

We have suggested a method for treating different quantum few-body dynamics without traditional using of the partial-wave analysis. It happened that this approach was very efficient in quantitative analysis of low-dimensional ultracold few-body systems arising in confined geometry of atomic traps. Here we discuss its application to a recently suggested mechanism of resonant molecule formation in confined two-component atomic mixture with transferring the energy release to the center-of-mass excitation of forming molecules. The author considers this result as one of the most significant in his scientific carrier which started from the model of resonant muonic molecule formation [S.I. Vinitsky etmore » al., Sov. Phys. JETP 47, 444 (1978)], one of the most citing works of S.I. Vinitsky.« less

Stencil computations for PDE-based applications with examples from DUNE and hypre

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

Engwer, C.; Falgout, R. D.; Yang, U. M.

Here, stencils are commonly used to implement efficient on–the–fly computations of linear operators arising from partial differential equations. At the same time the term “stencil” is not fully defined and can be interpreted differently depending on the application domain and the background of the software developers. Common features in stencil codes are the preservation of the structure given by the discretization of the partial differential equation and the benefit of minimal data storage. We discuss stencil concepts of different complexity, show how they are used in modern software packages like hypre and DUNE, and discuss recent efforts to extend themore » software to enable stencil computations of more complex problems and methods such as inf–sup–stable Stokes discretizations and mixed finite element discretizations.« less

On mass transport in porosity waves

NASA Astrophysics Data System (ADS)

Jordan, Jacob S.; Hesse, Marc A.; Rudge, John F.

2018-03-01

Porosity waves arise naturally from the equations describing fluid migration in ductile rocks. Here, we show that higher-dimensional porosity waves can transport mass and therefore preserve geochemical signatures, at least partially. Fluid focusing into these high porosity waves leads to recirculation in their center. This recirculating fluid is separated from the background flow field by a circular dividing streamline and transported with the phase velocity of the porosity wave. Unlike models for one-dimensional chromatography in geological porous media, tracer transport in higher-dimensional porosity waves does not produce chromatographic separations between relatively incompatible elements due to the circular flow pattern. This may allow melt that originated from the partial melting of fertile heterogeneities or fluid produced during metamorphism to retain distinct geochemical signatures as they rise buoyantly towards the surface.

Stencil computations for PDE-based applications with examples from DUNE and hypre

DOE PAGES

Engwer, C.; Falgout, R. D.; Yang, U. M.

2017-02-24

Here, stencils are commonly used to implement efficient on–the–fly computations of linear operators arising from partial differential equations. At the same time the term “stencil” is not fully defined and can be interpreted differently depending on the application domain and the background of the software developers. Common features in stencil codes are the preservation of the structure given by the discretization of the partial differential equation and the benefit of minimal data storage. We discuss stencil concepts of different complexity, show how they are used in modern software packages like hypre and DUNE, and discuss recent efforts to extend themore » software to enable stencil computations of more complex problems and methods such as inf–sup–stable Stokes discretizations and mixed finite element discretizations.« less

Triton - Scattering models and surface/atmosphere constraints

NASA Technical Reports Server (NTRS)

Thompson, W. Reid

1989-01-01

Modeling of Triton's spectrum indicates a bright scattering layer of optical depth tau about 3 overlying an optically deep layer of CH4 with high absorption and little scattering. UV absorption in the spectrum indicates tau about 0.3 of red-yellow haze, although some color may also arise from complex organics partially visible on the surface. An analysis of this and other (spectro)photometric evidence indicates that Triton most likely has a bright surface, which was partially visible in 1977-1980. Geometric albedo p = 0.62 + 0.18 or - 0.12 radius r = 1480 + or - 180 km, and temperature T = 48 + or - 6 K. With scattering optical depths of 0.3-3 and about 1-10 mb of N2, a Mars-like atmospheric density and surface visibility pertain.

Mean field games with congestion

NASA Astrophysics Data System (ADS)

Achdou, Yves; Porretta, Alessio

2018-03-01

We consider a class of systems of time dependent partial differential equations which arise in mean field type models with congestion. The systems couple a backward viscous Hamilton-Jacobi equation and a forward Kolmogorov equation both posed in $(0,T)\\times (\\mathbb{R}^N /\\mathbb{Z}^N)$. Because of congestion and by contrast with simpler cases, the latter system can never be seen as the optimality conditions of an optimal control problem driven by a partial differential equation. The Hamiltonian vanishes as the density tends to $+\\infty$ and may not even be defined in the regions where the density is zero. After giving a suitable definition of weak solutions, we prove the existence and uniqueness results of the latter under rather general assumptions. No restriction is made on the horizon $T$.

Soft Shoulders Ahead: Spurious Signatures of Soft and Partial Selective Sweeps Result from Linked Hard Sweeps

PubMed Central

Schrider, Daniel R.; Mendes, Fábio K.; Hahn, Matthew W.; Kern, Andrew D.

2015-01-01

Characterizing the nature of the adaptive process at the genetic level is a central goal for population genetics. In particular, we know little about the sources of adaptive substitution or about the number of adaptive variants currently segregating in nature. Historically, population geneticists have focused attention on the hard-sweep model of adaptation in which a de novo beneficial mutation arises and rapidly fixes in a population. Recently more attention has been given to soft-sweep models, in which alleles that were previously neutral, or nearly so, drift until such a time as the environment shifts and their selection coefficient changes to become beneficial. It remains an active and difficult problem, however, to tease apart the telltale signatures of hard vs. soft sweeps in genomic polymorphism data. Through extensive simulations of hard- and soft-sweep models, here we show that indeed the two might not be separable through the use of simple summary statistics. In particular, it seems that recombination in regions linked to, but distant from, sites of hard sweeps can create patterns of polymorphism that closely mirror what is expected to be found near soft sweeps. We find that a very similar situation arises when using haplotype-based statistics that are aimed at detecting partial or ongoing selective sweeps, such that it is difficult to distinguish the shoulder of a hard sweep from the center of a partial sweep. While knowing the location of the selected site mitigates this problem slightly, we show that stochasticity in signatures of natural selection will frequently cause the signal to reach its zenith far from this site and that this effect is more severe for soft sweeps; thus inferences of the target as well as the mode of positive selection may be inaccurate. In addition, both the time since a sweep ends and biologically realistic levels of allelic gene conversion lead to errors in the classification and identification of selective sweeps. This general problem of “soft shoulders” underscores the difficulty in differentiating soft and partial sweeps from hard-sweep scenarios in molecular population genomics data. The soft-shoulder effect also implies that the more common hard sweeps have been in recent evolutionary history, the more prevalent spurious signatures of soft or partial sweeps may appear in some genome-wide scans. PMID:25716978

Soft shoulders ahead: spurious signatures of soft and partial selective sweeps result from linked hard sweeps.

PubMed

Schrider, Daniel R; Mendes, Fábio K; Hahn, Matthew W; Kern, Andrew D

2015-05-01

Characterizing the nature of the adaptive process at the genetic level is a central goal for population genetics. In particular, we know little about the sources of adaptive substitution or about the number of adaptive variants currently segregating in nature. Historically, population geneticists have focused attention on the hard-sweep model of adaptation in which a de novo beneficial mutation arises and rapidly fixes in a population. Recently more attention has been given to soft-sweep models, in which alleles that were previously neutral, or nearly so, drift until such a time as the environment shifts and their selection coefficient changes to become beneficial. It remains an active and difficult problem, however, to tease apart the telltale signatures of hard vs. soft sweeps in genomic polymorphism data. Through extensive simulations of hard- and soft-sweep models, here we show that indeed the two might not be separable through the use of simple summary statistics. In particular, it seems that recombination in regions linked to, but distant from, sites of hard sweeps can create patterns of polymorphism that closely mirror what is expected to be found near soft sweeps. We find that a very similar situation arises when using haplotype-based statistics that are aimed at detecting partial or ongoing selective sweeps, such that it is difficult to distinguish the shoulder of a hard sweep from the center of a partial sweep. While knowing the location of the selected site mitigates this problem slightly, we show that stochasticity in signatures of natural selection will frequently cause the signal to reach its zenith far from this site and that this effect is more severe for soft sweeps; thus inferences of the target as well as the mode of positive selection may be inaccurate. In addition, both the time since a sweep ends and biologically realistic levels of allelic gene conversion lead to errors in the classification and identification of selective sweeps. This general problem of "soft shoulders" underscores the difficulty in differentiating soft and partial sweeps from hard-sweep scenarios in molecular population genomics data. The soft-shoulder effect also implies that the more common hard sweeps have been in recent evolutionary history, the more prevalent spurious signatures of soft or partial sweeps may appear in some genome-wide scans. Copyright © 2015 by the Genetics Society of America.

Maternal risk factors predicting child physical characteristics and dysmorphology in fetal alcohol syndrome and partial fetal alcohol syndrome.

PubMed

May, Philip A; Tabachnick, Barbara G; Gossage, J Phillip; Kalberg, Wendy O; Marais, Anna-Susan; Robinson, Luther K; Manning, Melanie; Buckley, David; Hoyme, H Eugene

2011-12-01

Previous research in South Africa revealed very high rates of fetal alcohol syndrome (FAS), of 46-89 per 1000 among young children. Maternal and child data from studies in this community summarize the multiple predictors of FAS and partial fetal alcohol syndrome (PFAS). Sequential regression was employed to examine influences on child physical characteristics and dysmorphology from four categories of maternal traits: physical, demographic, childbearing, and drinking. Then, a structural equation model (SEM) was constructed to predict influences on child physical characteristics. Individual sequential regressions revealed that maternal drinking measures were the most powerful predictors of a child's physical anomalies (R² = .30, p < .001), followed by maternal demographics (R² = .24, p < .001), maternal physical characteristics (R²=.15, p < .001), and childbearing variables (R² = .06, p < .001). The SEM utilized both individual variables and the four composite categories of maternal traits to predict a set of child physical characteristics, including a total dysmorphology score. As predicted, drinking behavior is a relatively strong predictor of child physical characteristics (β = 0.61, p < .001), even when all other maternal risk variables are included; higher levels of drinking predict child physical anomalies. Overall, the SEM model explains 62% of the variance in child physical anomalies. As expected, drinking variables explain the most variance. But this highly controlled estimation of multiple effects also reveals a significant contribution played by maternal demographics and, to a lesser degree, maternal physical and childbearing variables. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Iterative algorithms for large sparse linear systems on parallel computers

NASA Technical Reports Server (NTRS)

Adams, L. M.

1982-01-01

Algorithms for assembling in parallel the sparse system of linear equations that result from finite difference or finite element discretizations of elliptic partial differential equations, such as those that arise in structural engineering are developed. Parallel linear stationary iterative algorithms and parallel preconditioned conjugate gradient algorithms are developed for solving these systems. In addition, a model for comparing parallel algorithms on array architectures is developed and results of this model for the algorithms are given.

Exploiting Data Sparsity in Parallel Matrix Powers Computations

DTIC Science & Technology

2013-05-03

2013 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour...matrices of the form A = D+USV H, where D is sparse and USV H has low rank but may be dense. Matrices of this form arise in many practical applications...methods numerical partial di erential equation solvers, and preconditioned iterative methods. If A has this form , our algorithm enables a communication

Optimal Artificial Boundary Condition Configurations for Sensitivity-Based Model Updating and Damage Detection

DTIC Science & Technology

2010-09-01

matrix is used in many methods, like Jacobi or Gauss Seidel , for solving linear systems. Also, no partial pivoting is necessary for a strictly column...problems that arise during the procedure, which in general, converges to the solving of a linear system. The most common issue with the solution is the... iterative procedure to find an appropriate subset of parameters that produce an optimal solution commonly known as forward selection. Then, the

When structure affects function--the need for partial volume effect correction in functional and resting state magnetic resonance imaging studies.

PubMed

Dukart, Juergen; Bertolino, Alessandro

2014-01-01

Both functional and also more recently resting state magnetic resonance imaging have become established tools to investigate functional brain networks. Most studies use these tools to compare different populations without controlling for potential differences in underlying brain structure which might affect the functional measurements of interest. Here, we adapt a simulation approach combined with evaluation of real resting state magnetic resonance imaging data to investigate the potential impact of partial volume effects on established functional and resting state magnetic resonance imaging analyses. We demonstrate that differences in the underlying structure lead to a significant increase in detected functional differences in both types of analyses. Largest increases in functional differences are observed for highest signal-to-noise ratios and when signal with the lowest amount of partial volume effects is compared to any other partial volume effect constellation. In real data, structural information explains about 25% of within-subject variance observed in degree centrality--an established resting state connectivity measurement. Controlling this measurement for structural information can substantially alter correlational maps obtained in group analyses. Our results question current approaches of evaluating these measurements in diseased population with known structural changes without controlling for potential differences in these measurements.

Epileptic negative drop attacks in atypical benign partial epilepsy: a neurophysiological study.

PubMed

Hirano, Yoshiko; Oguni, Hirokazu; Osawa, Makiko

2009-03-01

We conducted a computer-assisted polygraphic analysis of drop attacks in a child with atypical benign partial epilepsy (ABPE) to investigate neurophysiological characteristics. The patient was a six-year two-month-old girl, who had started to have focal motor seizures, later combined with daily epileptic negative myoclonus (ENM) and drop attacks, causing multiple injuries. We studied episodes of ENM and drop attacks using video-polygraphic and computer-assisted back-averaging analysis. A total of 12 ENM episodes, seven involving the left arm (ENMlt) and five involving both arms (ENMbil), and five drop attacks were captured for analysis. All episodes were time-locked to spike-and-wave complexes (SWC) arising from both centro-temporo-parietal (CTP) areas. The latency between the onset of SWC and ENMlt, ENMbil, and drop attacks reached 68 ms, 42 ms, and 8 ms, respectively. The height of the spike as well as the slow-wave component of SWC for drop attacks were significantly larger than that for both ENMlt and ENMbil (p < 0.05). Drop attacks were considered to be epileptic negative myoclonus involving not only upper proximal but also axial muscles, causing the body to fall. Thus, drop attacks in ABPE are considered to be epileptic negative drop attacks arising from bilateral CTP foci and differ from drop attacks of a generalized origin seen in Lennox-Gastaut syndrome and myoclonic-astatic epilepsy.

Partially coherent polarized atmospheric transmission characteristics and application technology research

NASA Astrophysics Data System (ADS)

Fu, Qiang; Gao, Duorui; Liu, Zhi; Chen, Chunyi; Lou, Yan; Jiang, Huilin

2014-11-01

Based on partially coherent polarized light transmission characteristics of the atmosphere, an intensity expression of completely coherent flashing light is derived from Andrews scale modulation method. According to the generalized Huygens-Fresnel principle and Rytov theory, the phase fluctuation structure function is obtained on condition that the refractive index profile in the atmosphere meet Von Karman spectrum, then get the arrival Angle fluctuation variance. Through the RMS beam width of gaussian beams in turbulent atmosphere, deviation angle formula of fully coherent gaussian beams in turbulence atmosphere is attained, then get the RMS beam width of partially coherent and derivation angle expression of GSM beam in turbulent atmosphere. Combined with transmission properties of radial polarized laser beam, cross spectral density matrix of partially coherent radially polarized light can be gained by using generalized huygens-fresnel principle. And light intensity and polarization after transmission can be known according to the unity of coherence and polarization theory. On the basis of the analysis model and numerical simulation, the simulation results show that: the light spot caused by atmospheric turbulence of partially coherent polarization will be superior to completely polarized light.Taking advantage of this feature, designed a new wireless suppression technology of atmospheric turbulence, that is the optimization criterion of initial degree of coherent light beam. The optimal initial degree of coherent light beam will change along with the change of atmospheric turbulence conditions,make control the beam's initial degree of coherence to realize the initial degree of coherence of light beam in real time and dynamic control. A spatial phase screen before emission aperture of fully coherent light is to generate the partially coherent light, liquid crystal spatial light modulator is is a preferable way to realize the dynamic random phase. Finally look future of the application research of partially coherent light.

Multiple Brain Markers are Linked to Age-Related Variation in Cognition

PubMed Central

Hedden, Trey; Schultz, Aaron P.; Rieckmann, Anna; Mormino, Elizabeth C.; Johnson, Keith A.; Sperling, Reisa A.; Buckner, Randy L.

2016-01-01

Age-related alterations in brain structure and function have been challenging to link to cognition due to potential overlapping influences of multiple neurobiological cascades. We examined multiple brain markers associated with age-related variation in cognition. Clinically normal older humans aged 65–90 from the Harvard Aging Brain Study (N = 186) were characterized on a priori magnetic resonance imaging markers of gray matter thickness and volume, white matter hyperintensities, fractional anisotropy (FA), resting-state functional connectivity, positron emission tomography markers of glucose metabolism and amyloid burden, and cognitive factors of processing speed, executive function, and episodic memory. Partial correlation and mediation analyses estimated age-related variance in cognition shared with individual brain markers and unique to each marker. The largest relationships linked FA and striatum volume to processing speed and executive function, and hippocampal volume to episodic memory. Of the age-related variance in cognition, 70–80% was accounted for by combining all brain markers (but only ∼20% of total variance). Age had significant indirect effects on cognition via brain markers, with significant markers varying across cognitive domains. These results suggest that most age-related variation in cognition is shared among multiple brain markers, but potential specificity between some brain markers and cognitive domains motivates additional study of age-related markers of neural health. PMID:25316342

Coherent assembly of phytoplankton communities in diverse temperate ocean ecosystems

PubMed Central

Li, William K.W; Glen Harrison, W; Head, Erica J.H

2006-01-01

The annual cycle of phytoplankton cell abundance is coherent across diverse ecosystems in the temperate North Atlantic Ocean. In Bedford Basin, on the Scotian Shelf and in the Labrador Sea, the numerical abundance of phytoplankton is low in spring and high in autumn, thus in phase with the temperature cycle. Temperature aligns abundance on a common basis, effectively adjusting apparent cell discrepancies in waters that are colder or warmer than the regional norm. As an example of holistic simplicity arising from underlying complexity, the variance in a community variable (total abundance) is explained by a single predictor (temperature) to the extent of 75% in the marginal seas. In the estuarine basin, weekly averages of phytoplankton and temperature computed from a 13 year time-series yield a predictive relationship with 91% explained variance. Temperature-directed assembly of individual phytoplankton cells to form communities is statistically robust, consistent with observed biomass changes, amenable to theoretical analysis, and a sentinel for long-term change. Since cell abundance is a community property in the same units for all marine microbes at any trophic level and at any phylogenetic position, it promises to integrate biological oceanography into general ecology and evolution. PMID:16822757

A pattern recognition approach to transistor array parameter variance

NASA Astrophysics Data System (ADS)

da F. Costa, Luciano; Silva, Filipi N.; Comin, Cesar H.

2018-06-01

The properties of semiconductor devices, including bipolar junction transistors (BJTs), are known to vary substantially in terms of their parameters. In this work, an experimental approach, including pattern recognition concepts and methods such as principal component analysis (PCA) and linear discriminant analysis (LDA), was used to experimentally investigate the variation among BJTs belonging to integrated circuits known as transistor arrays. It was shown that a good deal of the devices variance can be captured using only two PCA axes. It was also verified that, though substantially small variation of parameters is observed for BJT from the same array, larger variation arises between BJTs from distinct arrays, suggesting the consideration of device characteristics in more critical analog designs. As a consequence of its supervised nature, LDA was able to provide a substantial separation of the BJT into clusters, corresponding to each transistor array. In addition, the LDA mapping into two dimensions revealed a clear relationship between the considered measurements. Interestingly, a specific mapping suggested by the PCA, involving the total harmonic distortion variation expressed in terms of the average voltage gain, yielded an even better separation between the transistor array clusters. All in all, this work yielded interesting results from both semiconductor engineering and pattern recognition perspectives.

Characterizing the D2 statistic: word matches in biological sequences.

PubMed

Forêt, Sylvain; Wilson, Susan R; Burden, Conrad J

2009-01-01

Word matches are often used in sequence comparison methods, either as a measure of sequence similarity or in the first search steps of algorithms such as BLAST or BLAT. The D2 statistic is the number of matches of words of k letters between two sequences. Recent advances have been made in the characterization of this statistic and in the approximation of its distribution. Here, these results are extended to the case of approximate word matches. We compute the exact value of the variance of the D2 statistic for the case of a uniform letter distribution, and introduce a method to provide accurate approximations of the variance in the remaining cases. This enables the distribution of D2 to be approximated for typical situations arising in biological research. We apply these results to the identification of cis-regulatory modules, and show that this method detects such sequences with a high accuracy. The ability to approximate the distribution of D2 for both exact and approximate word matches will enable the use of this statistic in a more precise manner for sequence comparison, database searches, and identification of transcription factor binding sites.

A Summary of Some Discrete-Event System Control Problems

NASA Astrophysics Data System (ADS)

Rudie, Karen

A summary of the area of control of discrete-event systems is given. In this research area, automata and formal language theory is used as a tool to model physical problems that arise in technological and industrial systems. The key ingredients to discrete-event control problems are a process that can be modeled by an automaton, events in that process that cannot be disabled or prevented from occurring, and a controlling agent that manipulates the events that can be disabled to guarantee that the process under control either generates all the strings in some prescribed language or as many strings as possible in some prescribed language. When multiple controlling agents act on a process, decentralized control problems arise. In decentralized discrete-event systems, it is presumed that the agents effecting control cannot each see all event occurrences. Partial observation leads to some problems that cannot be solved in polynomial time and some others that are not even decidable.

Some Work and Some Play: Microscopic and Macroscopic Approaches to Labor and Leisure

PubMed Central

Niyogi, Ritwik K.; Shizgal, Peter; Dayan, Peter

2014-01-01

Given the option, humans and other animals elect to distribute their time between work and leisure, rather than choosing all of one and none of the other. Traditional accounts of partial allocation have characterised behavior on a macroscopic timescale, reporting and studying the mean times spent in work or leisure. However, averaging over the more microscopic processes that govern choices is known to pose tricky theoretical problems, and also eschews any possibility of direct contact with the neural computations involved. We develop a microscopic framework, formalized as a semi-Markov decision process with possibly stochastic choices, in which subjects approximately maximise their expected returns by making momentary commitments to one or other activity. We show macroscopic utilities that arise from microscopic ones, and demonstrate how facets such as imperfect substitutability can arise in a more straightforward microscopic manner. PMID:25474151

Bone marrow metastasis of malignant melanoma in childhood arising within a congenital melanocytic nevus.

PubMed

Volejnikova, Jana; Bajciova, Viera; Sulovska, Lucie; Geierova, Marie; Buriankova, Eva; Jarosova, Marie; Hajduch, Marian; Sterba, Jaroslav; Mihal, Vladimir

2016-09-01

Malignant melanoma in childhood is infrequent and can arise within congenital melanocytic nevi. Spread of malignant melanoma to the bone marrow, especially in children, is extremely rare. Reported is a case of a 5-year-old boy with a congenital large melanocytic nevus of the head and neck who presented with a short history of low back and leg pain, fever and cervical lymphadenopathy. Despite regular follow-up by a dermatologist and plastic surgeon and repeatedly negative histology of previous partial excisions, diffuse bone marrow infiltration with malignant melanoma was diagnosed. The primary site was identified in the post-excision area. The disease progressed rapidly on ipilimumab immunotherapy and led to death at four months from the diagnosis. Surveillance is indispensable in children with a predisposition to melanoma and nonspecific symptoms such as bone pain, gait impairment or cytopenia, should always be taken into account.

Dedifferentiated liposarcoma arising from the mesocolon ascendens: report of a case.

PubMed

Takeda, Kohki; Aimoto, Takayuki; Yoshioka, Masato; Nakamura, Yoshiharu; Yamahatsu, Kazuya; Ishiwata, Toshiyuki; Naito, Zenya; Miyashita, Masao; Uchida, Eiji

2012-01-01

Dedifferentiated liposarcoma of the mesentery is an extremely rare tumor. A 71-year-old man with a 2-month history of abdominal distention was admitted to our department for evaluation and treatment of an abdominal mass. Computed tomography and magnetic resonance imaging revealed an 11 × 9 cm mass lesion with fat density in the upper right abdominal cavity, displacing the ascending and transverse colon ventrally. Abdominal angiography showed small feeding vessels of the tumor from the ileocolic artery and the middle colic artery. On basis of these findings, liposarcoma arising from the mesocolon ascendens was diagnosed, and complete removal of the tumor and central pancreatectomy (partial resection of the body of the pancreas) were performed. The histopathological diagnosis was dedifferentiated liposarcoma, and the patient is free from recurrence 6 months after surgery. The treatment strategy for abdominal dedifferentiated liposarcoma is surgical resection with a wide surgical margin.

Brain tumor presenting as somnambulism in an adolescent.

PubMed

Prashad, Priya S; Marcus, Carole L; Brown, Lawrence W; Dlugos, Dennis J; Feygin, Tamara; Harding, Brian N; Heuer, Gregory G; Mason, Thornton B Alexander

2013-09-01

Sleepwalking is typically a benign and self-limited non-rapid eye movement parasomnia of childhood. We describe an unusual 15-year-old boy referred to our sleep center for new-onset sleepwalking. An overnight polysomnogram was normal from a respiratory standpoint, but a concurrent extended electroencephalogram montage showed frequent epileptiform discharges from the right parietal-temporal region and two electroclinical seizures arising from the right-frontal-central-temporal region during sleep. Magnetic resonance imaging scan revealed a right parasagittal parietal region lesion consistent with a low-grade neoplasm, and surgical resection of the lesion demonstrated a right parietal dysembryoplastic neuroepithelial tumor. Complex partial seizures and sleepwalking remitted completely with anticonvulsant therapy following surgery. This patient highlights the differential diagnosis of nocturnal events appearing to be typical parasomnias, especially when they arise abruptly at an older age. Copyright © 2013 Elsevier Inc. All rights reserved.

New soliton solution to the longitudinal wave equation in a magneto-electro-elastic circular rod

NASA Astrophysics Data System (ADS)

Seadawy, Aly R.; Manafian, Jalil

2018-03-01

This paper examines the effectiveness of an integration scheme which called the extended trial equation method (ETEM) in exactly solving a well-known nonlinear equation of partial differential equations (PDEs). In this respect, the longitudinal wave equation (LWE) that arises in mathematical physics with dispersion caused by the transverse Poisson's effect in a magneto-electro-elastic (MEE) circular rod, which a series of exact traveling wave solutions for the aforementioned equation is formally extracted. Explicit new exact solutions are derived in different form such as dark solitons, bright solitons, solitary wave, periodic solitary wave, rational function, and elliptic function solutions of the longitudinal wave equation. The movements of obtained solutions are shown graphically, which helps to understand the physical phenomena of this longitudinal wave equation. Many other such types of nonlinear equations arising in non-destructive evaluation of structures made of the advanced MEE material can also be solved by this method.

Imaging DC MEG Fields Associated with Epileptic Onset

NASA Astrophysics Data System (ADS)

Weiland, B. J.; Bowyer, S. M.; Moran, J. E.; Jenrow, K.; Tepley, N.

2004-10-01

Magnetoencephalography (MEG) is a non-invasive brain imaging modality, with high spatial and temporal resolution, used to evaluate and quantify the magnetic fields associated with neuronal activity. Complex partial epileptic seizures are characterized by hypersynchronous neuronal activity believed to arise from a zone of epileptogenesis. This study investigated the characteristics of direct current (DC) MEG shifts arising at epileptic onset. MEG data were acquired with rats using a six-channel first order gradiometer system. Limbic status epilepticus was induced by IA (femoral) administration of kainic acid. DC-MEG shifts were observed at the onset of epileptic spike train activity and status epilepticus. Epilepsy is also being studied in patients undergoing presurgical mapping from the Comprehensive Epilepsy Center at Henry Ford Hospital using a whole head Neuromagnetometer. Preliminary data analysis shows that DC-MEG waveforms, qualitatively similar to those seen in the animal model, are evident prior to seizure activity in human subjects.

Low-Grade Astrocytoma within a Mature Cystic Teratoma in an Adolescent Patient.

PubMed

Yoder, Nicole; Marks, Asher; Hui, Pei; Litkouhi, Babak; Cron, Julia

2018-06-01

Mature cystic teratomas are the most common ovarian neoplasm in adolescents. They are typically benign, however, malignant transformation rarely occurs. We report a low-grade astrocytoma arising from a mature cystic teratoma in an adolescent patient. The patient was a 12-year-old girl with an asymptomatic ovarian cyst and subsequent cystectomy. Final pathology identified a solid tumor with glial tissue within the cyst, reported as low-grade astrocytoma arising in a mature cystic teratoma. There are few data on astrocytomas in the gynecologic tract. Risk factors for malignant transformation in a mature cystic teratoma include increased age, postmenopausal status, elevated carcinoma antigen 125, and large tumor size. Interestingly, this patient had a history of partial trisomy 20, which has been associated with teratoma formation in a mouse model. Copyright © 2017 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

Modified multiblock partial least squares path modeling algorithm with backpropagation neural networks approach

NASA Astrophysics Data System (ADS)

Yuniarto, Budi; Kurniawan, Robert

2017-03-01

PLS Path Modeling (PLS-PM) is different from covariance based SEM, where PLS-PM use an approach based on variance or component, therefore, PLS-PM is also known as a component based SEM. Multiblock Partial Least Squares (MBPLS) is a method in PLS regression which can be used in PLS Path Modeling which known as Multiblock PLS Path Modeling (MBPLS-PM). This method uses an iterative procedure in its algorithm. This research aims to modify MBPLS-PM with Back Propagation Neural Network approach. The result is MBPLS-PM algorithm can be modified using the Back Propagation Neural Network approach to replace the iterative process in backward and forward step to get the matrix t and the matrix u in the algorithm. By modifying the MBPLS-PM algorithm using Back Propagation Neural Network approach, the model parameters obtained are relatively not significantly different compared to model parameters obtained by original MBPLS-PM algorithm.

Sewall Wright's equation Deltaq=(q(1-q) partial differentialw/ partial differentialq)/2w.

PubMed

Edwards, A W

2000-02-01

An equation of Sewall Wright's expresses the change in the frequency of an allele under selection at a multiallelic locus as a function of the gradient of the mean fitness "surface" in the direction in which the relative proportions of the other alleles do not change. An attempt to derive this equation using conventional vector calculus shows that this description leads to a different equation and that the purported gradient in Wright's equation is not a gradient of the mean fitness surface except in the diallelic case, where the two equations are the same. It is further shown that if Fisher's angular transformation is applied to the diallelic case the genic variance is exactly equal to one-eighth of the square of the gradient of the mean fitness with respect to the transformed gene frequency. Copyright 2000 Academic Press.

The Extent and Prediction of Heavy Metal Pollution in Soils of Shahrood and Damghan, Iran.

PubMed

Sakizadeh, Mohamad; Mirzaei, Rouhollah; Ghorbani, Hadi

2015-12-01

The levels of 12 heavy metals (Ag, Ba, Be, Cd, Co, Cr, Cu, Ni, Pb, Tl, V, Zn) were considered in 229 soil samples in Semnan Province, Iran. To discriminate between natural and anthropogenic inputs of heavy metals, factor analysis was used. Seven factors accounting for 90.5 % of the total variance were extracted. The mining and agricultural activities along with geogenic sources have been attributed as the main causes of the levels of heavy metals in the study area. The partial least squares regression was utilized to predict the level of soil pollution index (SPI) considering the concentrations of 12 heavy metals. The eigenvectors from the first three PLS represented more than 98 % of the overall variance. The correlation coefficient between the observed and predicted SPI was 0.99 indicating the high efficiency of this method. The resultant coefficient of determination for three PLS components was 0.984 confirming the predictive ability of this method.

Metabolomics fingerprint of coffee species determined by untargeted-profiling study using LC-HRMS.

PubMed

Souard, Florence; Delporte, Cédric; Stoffelen, Piet; Thévenot, Etienne A; Noret, Nausicaa; Dauvergne, Bastien; Kauffmann, Jean-Michel; Van Antwerpen, Pierre; Stévigny, Caroline

2018-04-15

Coffee bean extracts are consumed all over the world as beverage and there is a growing interest in coffee leaf extracts as food supplements. The wild diversity in Coffea (Rubiaceae) genus is large and could offer new opportunities and challenges. In the present work, a metabolomics approach was implemented to examine leaf chemical composition of 9 Coffea species grown in the same environmental conditions. Leaves were analyzed by LC-HRMS and a comprehensive statistical workflow was designed. It served for univariate hypothesis testing and multivariate modeling by PCA and partial PLS-DA on the Workflow4Metabolomics infrastructure. The first two axes of PCA and PLS-DA describes more than 40% of variances with good values of explained variances. This strategy permitted to investigate the metabolomics data and their relation with botanic and genetic informations. Finally, the identification of several key metabolites for the discrimination between species was further characterized. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exploring the relationship between socioeconomic status, control beliefs and exercise behavior: a multiple mediator model.

PubMed

Murray, Terra C; Rodgers, Wendy M; Fraser, Shawn N

2012-02-01

The purpose of this study was to examine the relationship between control beliefs, socioeconomic status and exercise intentions and behavior. Specifically, we examined whether distal and proximal control beliefs mediated the association between socioeconomic status and exercise intentions and behavior. A one time, cross sectional mail out survey (N = 350) was conducted in a large urban Canadian city. Distal (i.e., personal constraints) and proximal (i.e., scheduling self-efficacy) control beliefs mediated the association between socioeconomic status and exercise, explaining approximately 30% of the variance. Proximal control beliefs (i.e., scheduling self-efficacy) partially mediated the association between socioeconomic status and intentions, with the models explaining approximately 50% of the variance. Compared to individuals with lower socioeconomic status, individuals with higher socioeconomic status reported more exercise and stronger intentions to exercise. This was at least partly because higher socioeconomic status respondents reported fewer barriers in their lives, and were more confident to cope with the scheduling demands of exercise.

Stereotyped behavior of severely disabled children in classroom and free-play settings.

PubMed

Thompson, T J; Berkson, G

1985-05-01

The relationships between stereotyped behavior, object manipulation, self-manipulation, teacher attention, and various developmental measures were examined in 101 severely developmentally disabled children in their classrooms and a free-play setting. Stereotyped behavior without objects was positively correlated with self-manipulation and CA and was negatively correlated with complex object manipulation, developmental age, developmental quotient, and teacher attention. Stereotyped behavior with objects was negatively correlated with complex object manipulation. Partial correlations showed that age, self-manipulation, and developmental age shared unique variance with stereotyped behavior without objects.

Numerical solution of a coupled pair of elliptic equations from solid state electronics

NASA Technical Reports Server (NTRS)

Phillips, T. N.

1983-01-01

Iterative methods are considered for the solution of a coupled pair of second order elliptic partial differential equations which arise in the field of solid state electronics. A finite difference scheme is used which retains the conservative form of the differential equations. Numerical solutions are obtained in two ways, by multigrid and dynamic alternating direction implicit methods. Numerical results are presented which show the multigrid method to be an efficient way of solving this problem.

Gain dependent self-phasing in a two-core coherently combined fiber laser.

PubMed

Kunkel, W Minster; Leger, James R

2018-04-16

The influence of the Kramers-Kronig phase is demonstrated in a coherently combined fiber laser where other passive phasing mechanisms such as wavelength tuning have been suppressed. A mathematical model is developed to predict the lasing supermode and is supported by experimental measurements of the gain, phase, and power. The results show that the difference in Kramers-Kronig phase arising from a difference in gain between the two arms partially compensates for an externally applied phase error.

[Spontaneous and induced sterility by ethyl methanesulfonate (EMS) in Nigella damascena L].

PubMed

Gilot-Delhalle, J

1976-01-01

EMS-induced sterility could be very partially due to chromosomal aberrations appearing during male and female meiosis or even to mechanical abnormalities of the double fertilization. The sterility could be also related to diplontic origin (lethal factors or small deficiencies appearing in homozygous state on account of self-pollinization). Owing to our histological and genetical data, a female gametophytic origin could be mainly ascribed to EMS induced sterility. It could arise from a damage of the feeding function of the nucellus.

Time domain convergence properties of Lyapunov stable penalty methods

NASA Technical Reports Server (NTRS)

Kurdila, A. J.; Sunkel, John

1991-01-01

Linear hyperbolic partial differential equations are analyzed using standard techniques to show that a sequence of solutions generated by the Liapunov stable penalty equations approaches the solution of the differential-algebraic equations governing the dynamics of multibody problems arising in linear vibrations. The analysis does not require that the system be conservative and does not impose any specific integration scheme. Variational statements are derived which bound the error in approximation by the norm of the constraint violation obtained in the approximate solutions.

An experimental investigation of velocity fields in divergent glottal models of the human vocal tract

NASA Astrophysics Data System (ADS)

Erath, Byron D.; Plesniak, Michael W.

2005-09-01

In speech, sound production arises from fluid-structure interactions within the larynx as well as viscous flow phenomena that is most likely to occur during the divergent orientation of the vocal folds. Of particular interest are the flow mechanisms that influence the location of flow separation points on the vocal folds walls. Physiologically scaled pulsatile flow fields in 7.5 times real size static divergent glottal models were investigated. Three divergence angles were investigated using phase-averaged particle image velocimetry (PIV). The pulsatile glottal jet exhibited a bi-modal stability toward both glottal walls, although there was a significant amount of variance in the angle the jet deflected from the midline. The attachment of the Coanda effect to the glottal model walls occurred when the pulsatile velocity was a maximum, and the acceleration of the waveform was zero. The location of the separation and reattachment points of the flow from the glottal models was a function of the velocity waveform and divergence angle. Acoustic analogies show that a dipole sound source contribution arising from the fluid interaction (Coanda jet) with the vocal fold walls is expected. [Work funded by NIH Grant RO1 DC03577.

Sample size calculation for studies with grouped survival data.

PubMed

Li, Zhiguo; Wang, Xiaofei; Wu, Yuan; Owzar, Kouros

2018-06-10

Grouped survival data arise often in studies where the disease status is assessed at regular visits to clinic. The time to the event of interest can only be determined to be between two adjacent visits or is right censored at one visit. In data analysis, replacing the survival time with the endpoint or midpoint of the grouping interval leads to biased estimators of the effect size in group comparisons. Prentice and Gloeckler developed a maximum likelihood estimator for the proportional hazards model with grouped survival data and the method has been widely applied. Previous work on sample size calculation for designing studies with grouped data is based on either the exponential distribution assumption or the approximation of variance under the alternative with variance under the null. Motivated by studies in HIV trials, cancer trials and in vitro experiments to study drug toxicity, we develop a sample size formula for studies with grouped survival endpoints that use the method of Prentice and Gloeckler for comparing two arms under the proportional hazards assumption. We do not impose any distributional assumptions, nor do we use any approximation of variance of the test statistic. The sample size formula only requires estimates of the hazard ratio and survival probabilities of the event time of interest and the censoring time at the endpoints of the grouping intervals for one of the two arms. The formula is shown to perform well in a simulation study and its application is illustrated in the three motivating examples. Copyright © 2018 John Wiley & Sons, Ltd.

Three tests and three corrections: Comment on Koen and Yonelinas (2010)

PubMed Central

Jang, Yoonhee; Mickes, Laura; Wixted, John T.

2012-01-01

The slope of the z-transformed receiver-operating characteristic (zROC) in recognition memory experiments is usually less than 1, which has long been interpreted to mean that the variance of the target distribution is greater than the variance of the lure distribution. The greater variance of the target distribution could arise because the different items on a list receive different increments in memory strength during study (the “encoding variability” hypothesis). In a test of that interpretation, J. Koen and A. Yonelinas (2010, K&Y) attempted to further increase encoding variability to see if it would further decrease the slope of the zROC. To do so, they presented items on a list for two different durations and then mixed the weak and strong targets together. After performing three tests on the mixed-strength data, K&Y concluded that encoding variability does not explain why the slope of the zROC is typically less than one. However, we show that their tests have no bearing on the encoding variability account. Instead, they bear on the mixture-UVSD model that corresponds to their experimental design. On the surface, the results reported by K&Y appear to be inconsistent with the predictions of the mixture-UVSD model (though they were taken to be inconsistent with the predictions of the encoding variability hypothesis). However, all three of the tests they performed contained errors. When those errors are corrected, the same three tests show that their data support, rather than contradict, the mixture-UVSD model (but they still have no bearing on the encoding variability hypothesis). PMID:22390323

Corruption of the dentate gyrus by "dominant" granule cells: Implications for dentate gyrus function in health and disease.

PubMed

Scharfman, Helen E; Myers, Catherine E

2016-03-01

The dentate gyrus (DG) and area CA3 of the hippocampus are highly organized lamellar structures which have been implicated in specific cognitive functions such as pattern separation and pattern completion. Here we describe how the anatomical organization and physiology of the DG and CA3 are consistent with structures that perform pattern separation and completion. We then raise a new idea related to the complex circuitry of the DG and CA3 where CA3 pyramidal cell 'backprojections' play a potentially important role in the sparse firing of granule cells (GCs), considered important in pattern separation. We also propose that GC axons, the mossy fibers, already known for their highly specialized structure, have a dynamic function that imparts variance--'mossy fiber variance'--which is important to pattern separation and completion. Computational modeling is used to show that when a subset of GCs become 'dominant,' one consequence is loss of variance in the activity of mossy fiber axons and a reduction in pattern separation and completion in the model. Empirical data are then provided using an example of 'dominant' GCs--subsets of GCs that develop abnormally and have increased excitability. Notably, these abnormal GCs have been identified in animal models of disease where DG-dependent behaviors are impaired. Together these data provide insight into pattern separation and completion, and suggest that behavioral impairment could arise from dominance of a subset of GCs in the DG-CA3 network. Copyright © 2015 Elsevier Inc. All rights reserved.

Stochastic partial differential fluid equations as a diffusive limit of deterministic Lagrangian multi-time dynamics.

PubMed

Cotter, C J; Gottwald, G A; Holm, D D

2017-09-01

In Holm (Holm 2015 Proc. R. Soc. A 471 , 20140963. (doi:10.1098/rspa.2014.0963)), stochastic fluid equations were derived by employing a variational principle with an assumed stochastic Lagrangian particle dynamics. Here we show that the same stochastic Lagrangian dynamics naturally arises in a multi-scale decomposition of the deterministic Lagrangian flow map into a slow large-scale mean and a rapidly fluctuating small-scale map. We employ homogenization theory to derive effective slow stochastic particle dynamics for the resolved mean part, thereby obtaining stochastic fluid partial equations in the Eulerian formulation. To justify the application of rigorous homogenization theory, we assume mildly chaotic fast small-scale dynamics, as well as a centring condition. The latter requires that the mean of the fluctuating deviations is small, when pulled back to the mean flow.

Health-related quality of life and emotional distress in patients with dizziness: a cross-sectional approach to disentangle their relationship

PubMed Central

2014-01-01

Background Dizziness is frequently encountered in medical practice, often takes a chronic course and can impair the health related quality of life (HRQoL). However results on the extent of this impairment of HRQoL are mixed. Furthermore, the relationship between dizziness and the HRQoL is only partially understood. The role of clinical symptoms of dizziness and psychosocial factors such as emotional distress on this relationship is for the most part unknown. Methods The cross-sectional study evaluated the HRQoL in 203 patients suffering from dizziness, using the Medical Outcomes Studies 36-Item Short-Form Health-Survey (SF-36). The results were correlated with the severity of dizziness, using the Dizziness Handicap-Inventory (DHI), with emotional distress, using the Hospital Anxiety and Depression-Scale (HADS) and with further clinical symptoms and psychosocial parameters. In a multivariate hierarchical regression analysis associated variables which explain significant variance of the mental and physical HRQoL (MCS-36, PCS-36) were identified. Results Patients suffering from dizziness showed a markedly reduced mental and physical HRQoL. Higher DHI and HADS scores were correlated with lower MCS-36 and PCS-36 scores. Taken together DHI and vertigo characteristics of dizziness explained 38% of the variance of PCS-36. Overall explained variance of PCS-36 was 45%. HADS and living with a significant other explained 66% of the variance of MCS-36 (overall variance explained: 69%). Conclusion Both the physical and mental HRQoL are significantly impaired in patients with dizziness. While the impairment in PCS-36 can be explained by clinical symptoms of the dizziness, MCS-36 impairment is largely associated with psychosocial factors. To improve the patient’s overall well-being significantly and permanently doctors have to keep in mind both, the clinical symptoms and the psychosocial factors. Therefore, in addition to the physical examination doctors should integrate a basic psychological examination into the daily routine with dizziness patients. PMID:25052136

Global expression for representing cohesive-energy curves. II

NASA Technical Reports Server (NTRS)

Schlosser, Herbert; Ferrante, John

1993-01-01

Schlosser et al. (1991) showed that the R dependence of the cohesive energy of partially ionic solids may be characterized by a two-term energy relationship consisting of a Coulomb term arising from the charge transfer, delta-Z, and a scaled universal energy function, E*(a *), which accounts for the partially covalent character of the bond and for repulsion between the atomic cores for small R; a* is a scaled length. In the paper by Schlosser et al., the normalized cohesive-energy curves of NaCl-structure alkali-halide crystals were generated with this expression. In this paper we generate the cohesive-energy curves of several families of partially ionic solids with different crystal structures and differing degrees of ionicity. These include the CsCl-structure Cs halides, and the Tl and Ag halides, which have weaker ionic bonding than the alkali halides, and which have the CsCl and NaCl structures, respectively. The cohesive-energy-curve parameters are then used to generate theoretical isothermal compression curves for the Li, Na, K, Cs, and Ag halides. We find good agreement with the available experimental compression data.

A fast direct method for block triangular Toeplitz-like with tri-diagonal block systems from time-fractional partial differential equations

NASA Astrophysics Data System (ADS)

Ke, Rihuan; Ng, Michael K.; Sun, Hai-Wei

2015-12-01

In this paper, we study the block lower triangular Toeplitz-like with tri-diagonal blocks system which arises from the time-fractional partial differential equation. Existing fast numerical solver (e.g., fast approximate inversion method) cannot handle such linear system as the main diagonal blocks are different. The main contribution of this paper is to propose a fast direct method for solving this linear system, and to illustrate that the proposed method is much faster than the classical block forward substitution method for solving this linear system. Our idea is based on the divide-and-conquer strategy and together with the fast Fourier transforms for calculating Toeplitz matrix-vector multiplication. The complexity needs O (MNlog2 ⁡ M) arithmetic operations, where M is the number of blocks (the number of time steps) in the system and N is the size (number of spatial grid points) of each block. Numerical examples from the finite difference discretization of time-fractional partial differential equations are also given to demonstrate the efficiency of the proposed method.

Partial trisomy 11q involving chromosome 1 detected by fluorescence in situ hybridization

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

McCorquodale, M.; Bereziouk, O.; McCorquodale, D.J.

1994-09-01

Partial trisomy 11q was detected in an infant delivered 3-4 weeks prematurely. The phenotype included slanted palpebral fissures, high arched palate, developmental delay, microcephaly, and cardiac defects, all of which occur in the majority of cases with this syndrome. Other features included a column-shaped skull, preauricular pit, single palmar crease, short, broad great toes, flat occiput, unilateral kidney agenesis, and strabismus. Chromosomes obtained from peripheral blood cells revealed the presence of extra material on the long arm of chromosome 1. The G-banding pattern of this extra material indicated that it might be derived from chromosome 1 or 11. Chromosomal {open_quotes}paints{close_quotes}more » showed that it was not chromosome 1 material, but was chromosome 11 material extending from band q21 to qter. Partial trisomy 11q arising from translocation of the 11q material to chromosome 2, 3, 4, 5, 6, 9, 10, 13, 17, 21, 22, and X has been reported previously, whereas translocation to chromosome 1 has not. The chromosome to which the 11q material is translocated does not alter the most frequent features of the partial trisomy 11q syndrome, but may influence other less common features.« less

Response of a partially penetrating well in a heterogeneous aquifer: integrated well-face flux vs. uniform well-face flux boundary conditions

NASA Astrophysics Data System (ADS)

Ruud, N. C.; Kabala, Z. J.

1997-07-01

A two-dimensional integrated well-face flux (IWFF) model is developed for computing the drawdown at the well-face and around a fully or partially penetrating well with wellbore storage, situated in a layered confined aquifer. In this model, we calculate drawdown and well-face flux distributions by numerically solving a two-dimensional diffusion equation in cylindrical coordinates subject to appropriate initial and boundary conditions and to the well-face boundary constraint of an integrated well-face flux rather than the physically inconsistent uniform well-face flux boundary condition (the UWFF model). The differences between the IWFF and UWFF models in a partially penetrating well situated in a homogeneous isotropic aquifer are insignificant for wellbore drawdown (less than 3%) but are pronounced for the well-face flux. In fact, the latter strongly deviates from uniformity as the ratio of the screen length to the aquifer thickness decreases. For partially penetrating wells situated in multilayer aquifers, significant differences between the two models may arise, especially if the screen is not located in the most conductive layer. These differences depend on the hydraulic conductivity contrast of the adjacent layers. Consequently, the uniform well-face flux boundary condition should be used with extreme caution.

Allosteric Partial Inhibition of Monomeric Proteases. Sulfated Coumarins Induce Regulation, not just Inhibition, of Thrombin

PubMed Central

Verespy III, Stephen; Mehta, Akul Y.; Afosah, Daniel; Al-Horani, Rami A.; Desai, Umesh R.

2016-01-01

Allosteric partial inhibition of soluble, monomeric proteases can offer major regulatory advantages, but remains a concept on paper to date; although it has been routinely documented for receptors and oligomeric proteins. Thrombin, a key protease of the coagulation cascade, displays significant conformational plasticity, which presents an attractive opportunity to discover small molecule probes that induce sub-maximal allosteric inhibition. We synthesized a focused library of some 36 sulfated coumarins to discover two agents that display sub-maximal efficacy (~50%), high potency (<500 nM) and high selectivity for thrombin (>150-fold). Michaelis-Menten, competitive inhibition, and site-directed mutagenesis studies identified exosite 2 as the site of binding for the most potent sulfated coumarin. Stern-Volmer quenching of active site-labeled fluorophore suggested that the allosteric regulators induce intermediate structural changes in the active site as compared to those that display ~80–100% efficacy. Antithrombin inactivation of thrombin was impaired in the presence of the sulfated coumarins suggesting that allosteric partial inhibition arises from catalytic dysfunction of the active site. Overall, sulfated coumarins represent first-in-class, sub-maximal inhibitors of thrombin. The probes establish the concept of allosteric partial inhibition of soluble, monomeric proteins. This concept may lead to a new class of anticoagulants that are completely devoid of bleeding. PMID:27053426

The efficiency of genome-wide selection for genetic improvement of net merit.

PubMed

Togashi, K; Lin, C Y; Yamazaki, T

2011-10-01

Four methods of selection for net merit comprising 2 correlated traits were compared in this study: 1) EBV-only index (I₁), which consists of the EBV of both traits (i.e., traditional 2-trait BLUP selection); 2) GEBV-only index (I₂), which comprises the genomic EBV (GEBV) of both traits; 3) GEBV-assisted index (I₃), which combines both the EBV and the GEBV of both traits; and 4) GBV-assisted index (I₄), which combines both the EBV and the true genomic breeding value (GBV) of both traits. Comparisons of these indices were based on 3 evaluation criteria [selection accuracy, genetic response (ΔH), and relative efficiency] under 64 scenarios that arise from combining 2 levels of genetic correlation (r(G)), 2 ratios of genetic variances between traits, 2 ratios of the genomic variance to total genetic variances for trait 1, 4 accuracies of EBV, and 2 proportions of r(G) explained by the GBV. Both selection accuracy and genetic responses of the indices I₁, I₃, and I₄ increased as the accuracy of EBV increased, but the efficiency of the indices I₃ and I₄ relative to I₁ decreased as the accuracy of EBV increased. The relative efficiency of both I₃ and I₄ was generally greater when the accuracy of EBV was 0.6 than when it was 0.9, suggesting that the genomic markers are most useful to assist selection when the accuracy of EBV is low. The GBV-assisted index I₄ was superior to the GEBV-assisted I₃ in all 64 cases examined, indicating the importance of improving the accuracy of prediction of genomic breeding values. Other parameters being identical, increasing the genetic variance of a high heritability trait would increase the genetic response of the genomic indices (I₂, I₃, and I₄). The genetic responses to I₂, I₃, and I(4) was greater when the genetic correlation between traits was positive (r(G) = 0.5) than when it was negative (r(G) = -0.5). The results of this study indicate that the effectiveness of the GEBV-assisted index I₃ is affected by heritability of and genetic correlation between traits, the ratio of genetic variances between traits, the genomic-genetic variance ratio of each index trait, the proportion of genetic correlation accounted for by the genomic markers, and the accuracy of predictions of both EBV and GBV. However, most of these affecting factors are genetic characteristics of a population that is beyond the control of the breeders. The key factor subject to manipulation is to maximize both the proportion of the genetic variance explained by GEBV and the accuracy of both GEBV and EBV. The developed procedures provide means to investigate the efficiency of various genomic indices for any given combination of the genetic factors studied.

Predictive ability of mid-infrared spectroscopy for major mineral composition and coagulation traits of bovine milk by using the uninformative variable selection algorithm.

PubMed

Visentin, G; Penasa, M; Gottardo, P; Cassandro, M; De Marchi, M

2016-10-01

Milk minerals and coagulation properties are important for both consumers and processors, and they can aid in increasing milk added value. However, large-scale monitoring of these traits is hampered by expensive and time-consuming reference analyses. The objective of the present study was to develop prediction models for major mineral contents (Ca, K, Mg, Na, and P) and milk coagulation properties (MCP: rennet coagulation time, curd-firming time, and curd firmness) using mid-infrared spectroscopy. Individual milk samples (n=923) of Holstein-Friesian, Brown Swiss, Alpine Grey, and Simmental cows were collected from single-breed herds between January and December 2014. Reference analysis for the determination of both mineral contents and MCP was undertaken with standardized methods. For each milk sample, the mid-infrared spectrum in the range from 900 to 5,000cm(-1) was stored. Prediction models were calibrated using partial least squares regression coupled with a wavenumber selection technique called uninformative variable elimination, to improve model accuracy, and validated both internally and externally. The average reduction of wavenumbers used in partial least squares regression was 80%, which was accompanied by an average increment of 20% of the explained variance in external validation. The proportion of explained variance in external validation was about 70% for P, K, Ca, and Mg, and it was lower (40%) for Na. Milk coagulation properties prediction models explained between 54% (rennet coagulation time) and 56% (curd-firming time) of the total variance in external validation. The ratio of standard deviation of each trait to the respective root mean square error of prediction, which is an indicator of the predictive ability of an equation, suggested that the developed models might be effective for screening and collection of milk minerals and coagulation properties at the population level. Although prediction equations were not accurate enough to be proposed for analytic purposes, mid-infrared spectroscopy predictions could be evaluated as phenotypic information to genetically improve milk minerals and MCP on a large scale. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Mathematical (Dis)abilities Within the Opportunity-Propensity Model: The Choice of Math Test Matters

PubMed Central

Baten, Elke; Desoete, Annemie

2018-01-01

This study examined individual differences in mathematics learning by combining antecedent (A), opportunity (O), and propensity (P) indicators within the Opportunity-Propensity Model. Although there is already some evidence for this model based on secondary datasets, there currently is no primary data available that simultaneously takes into account A, O, and P factors in children with and without Mathematical Learning Disabilities (MLD). Therefore, the mathematical abilities of 114 school-aged children (grade 3 till 6) with and without MLD were analyzed and combined with information retrieved from standardized tests and questionnaires. Results indicated significant differences in personality, motivation, temperament, subjective well-being, self-esteem, self-perceived competence, and parental aspirations when comparing children with and without MLD. In addition, A, O, and P factors were found to underlie mathematical abilities and disabilities. For the A factors, parental aspirations explained about half of the variance in fact retrieval speed in children without MLD, and SES was especially involved in the prediction of procedural accuracy in general. Teachers’ experience contributed as O factor and explained about 6% of the variance in mathematical abilities. P indicators explained between 52 and 69% of the variance, with especially intelligence as overall significant predictor. Indirect effects pointed towards the interrelatedness of the predictors and the value of including A, O, and P indicators in a comprehensive model. The role parental aspirations played in fact retrieval speed was partially mediated through the self-perceived competence of the children, whereas the effect of SES on procedural accuracy was partially mediated through intelligence in children of both groups and through working memory capacity in children with MLD. Moreover, in line with the componential structure of mathematics, our findings were dependent on the math task used. Different A, O, and P indicators seemed to be important for fact retrieval speed compared to procedural accuracy. Also, mathematical development type (MLD or typical development) mattered since some A, O, and P factors were predictive for MLD only and the other way around. Practical implications of these findings and recommendations for future research on MLD and on individual differences in mathematical abilities are provided. PMID:29867645

Mathematical (Dis)abilities Within the Opportunity-Propensity Model: The Choice of Math Test Matters.

PubMed

Baten, Elke; Desoete, Annemie

2018-01-01

This study examined individual differences in mathematics learning by combining antecedent (A), opportunity (O), and propensity (P) indicators within the Opportunity-Propensity Model. Although there is already some evidence for this model based on secondary datasets, there currently is no primary data available that simultaneously takes into account A, O, and P factors in children with and without Mathematical Learning Disabilities (MLD). Therefore, the mathematical abilities of 114 school-aged children (grade 3 till 6) with and without MLD were analyzed and combined with information retrieved from standardized tests and questionnaires. Results indicated significant differences in personality, motivation, temperament, subjective well-being, self-esteem, self-perceived competence, and parental aspirations when comparing children with and without MLD. In addition, A, O, and P factors were found to underlie mathematical abilities and disabilities. For the A factors, parental aspirations explained about half of the variance in fact retrieval speed in children without MLD, and SES was especially involved in the prediction of procedural accuracy in general. Teachers' experience contributed as O factor and explained about 6% of the variance in mathematical abilities. P indicators explained between 52 and 69% of the variance, with especially intelligence as overall significant predictor. Indirect effects pointed towards the interrelatedness of the predictors and the value of including A, O, and P indicators in a comprehensive model. The role parental aspirations played in fact retrieval speed was partially mediated through the self-perceived competence of the children, whereas the effect of SES on procedural accuracy was partially mediated through intelligence in children of both groups and through working memory capacity in children with MLD. Moreover, in line with the componential structure of mathematics, our findings were dependent on the math task used. Different A, O, and P indicators seemed to be important for fact retrieval speed compared to procedural accuracy. Also, mathematical development type (MLD or typical development) mattered since some A, O, and P factors were predictive for MLD only and the other way around. Practical implications of these findings and recommendations for future research on MLD and on individual differences in mathematical abilities are provided.

Constraints on Inflation from Polarization and CMB Spectral Distortions

NASA Astrophysics Data System (ADS)

Kamionkowski, Marc

2014-01-01

This talk will summarize some things we can do with future CMB experiments to study the early Universe. An obvious first is to map the polarization from density perturbations to the cosmic-variance limit to improve upon the types of things (cosmological-parameter determination, lensing, etc.) that have been done so far with the temperature. Another direction, which already has considerable momentum, is the pursuit of the characteristic polarization signature of inflationary gravitational waves. But there is also a strong case, which I will review, now being assembled for a space mission to seek the tiny but nonzero departures from a blackbody spectrum that are expected in the standard cosmological model and that may arise from several interesting exotic mechanisms.

Molecular clock on a neutral network.

PubMed

Raval, Alpan

2007-09-28

The number of fixed mutations accumulated in an evolving population often displays a variance that is significantly larger than the mean (the overdispersed molecular clock). By examining a generic evolutionary process on a neutral network of high-fitness genotypes, we establish a formalism for computing all cumulants of the full probability distribution of accumulated mutations in terms of graph properties of the neutral network, and use the formalism to prove overdispersion of the molecular clock. We further show that significant overdispersion arises naturally in evolution when the neutral network is highly sparse, exhibits large global fluctuations in neutrality, and small local fluctuations in neutrality. The results are also relevant for elucidating aspects of neutral network topology from empirical measurements of the substitution process.

Molecular Clock on a Neutral Network

NASA Astrophysics Data System (ADS)

Raval, Alpan

2007-09-01

The number of fixed mutations accumulated in an evolving population often displays a variance that is significantly larger than the mean (the overdispersed molecular clock). By examining a generic evolutionary process on a neutral network of high-fitness genotypes, we establish a formalism for computing all cumulants of the full probability distribution of accumulated mutations in terms of graph properties of the neutral network, and use the formalism to prove overdispersion of the molecular clock. We further show that significant overdispersion arises naturally in evolution when the neutral network is highly sparse, exhibits large global fluctuations in neutrality, and small local fluctuations in neutrality. The results are also relevant for elucidating aspects of neutral network topology from empirical measurements of the substitution process.

Weak Lensing by Large-Scale Structure: A Dark Matter Halo Approach.

PubMed

Cooray; Hu; Miralda-Escudé

2000-05-20

Weak gravitational lensing observations probe the spectrum and evolution of density fluctuations and the cosmological parameters that govern them, but they are currently limited to small fields and subject to selection biases. We show how the expected signal from large-scale structure arises from the contributions from and correlations between individual halos. We determine the convergence power spectrum as a function of the maximum halo mass and so provide the means to interpret results from surveys that lack high-mass halos either through selection criteria or small fields. Since shot noise from rare massive halos is mainly responsible for the sample variance below 10&arcmin;, our method should aid our ability to extract cosmological information from small fields.

A Model of Compound Heterozygous, Loss-of-Function Alleles Is Broadly Consistent with Observations from Complex-Disease GWAS Datasets

PubMed Central

Sanjak, Jaleal S.; Long, Anthony D.; Thornton, Kevin R.

2017-01-01

The genetic component of complex disease risk in humans remains largely unexplained. A corollary is that the allelic spectrum of genetic variants contributing to complex disease risk is unknown. Theoretical models that relate population genetic processes to the maintenance of genetic variation for quantitative traits may suggest profitable avenues for future experimental design. Here we use forward simulation to model a genomic region evolving under a balance between recurrent deleterious mutation and Gaussian stabilizing selection. We consider multiple genetic and demographic models, and several different methods for identifying genomic regions harboring variants associated with complex disease risk. We demonstrate that the model of gene action, relating genotype to phenotype, has a qualitative effect on several relevant aspects of the population genetic architecture of a complex trait. In particular, the genetic model impacts genetic variance component partitioning across the allele frequency spectrum and the power of statistical tests. Models with partial recessivity closely match the minor allele frequency distribution of significant hits from empirical genome-wide association studies without requiring homozygous effect sizes to be small. We highlight a particular gene-based model of incomplete recessivity that is appealing from first principles. Under that model, deleterious mutations in a genomic region partially fail to complement one another. This model of gene-based recessivity predicts the empirically observed inconsistency between twin and SNP based estimated of dominance heritability. Furthermore, this model predicts considerable levels of unexplained variance associated with intralocus epistasis. Our results suggest a need for improved statistical tools for region based genetic association and heritability estimation. PMID:28103232

Statistical representative elementary volumes of porous media determined using greyscale analysis of 3D tomograms

NASA Astrophysics Data System (ADS)

Bruns, S.; Stipp, S. L. S.; Sørensen, H. O.

2017-09-01

Digital rock physics carries the dogmatic concept of having to segment volume images for quantitative analysis but segmentation rejects huge amounts of signal information. Information that is essential for the analysis of difficult and marginally resolved samples, such as materials with very small features, is lost during segmentation. In X-ray nanotomography reconstructions of Hod chalk we observed partial volume voxels with an abundance that limits segmentation based analysis. Therefore, we investigated the suitability of greyscale analysis for establishing statistical representative elementary volumes (sREV) for the important petrophysical parameters of this type of chalk, namely porosity, specific surface area and diffusive tortuosity, by using volume images without segmenting the datasets. Instead, grey level intensities were transformed to a voxel level porosity estimate using a Gaussian mixture model. A simple model assumption was made that allowed formulating a two point correlation function for surface area estimates using Bayes' theory. The same assumption enables random walk simulations in the presence of severe partial volume effects. The established sREVs illustrate that in compacted chalk, these simulations cannot be performed in binary representations without increasing the resolution of the imaging system to a point where the spatial restrictions of the represented sample volume render the precision of the measurement unacceptable. We illustrate this by analyzing the origins of variance in the quantitative analysis of volume images, i.e. resolution dependence and intersample and intrasample variance. Although we cannot make any claims on the accuracy of the approach, eliminating the segmentation step from the analysis enables comparative studies with higher precision and repeatability.

Model Uncertainty Quantification Methods For Data Assimilation In Partially Observed Multi-Scale Systems

NASA Astrophysics Data System (ADS)

Pathiraja, S. D.; van Leeuwen, P. J.

2017-12-01

Model Uncertainty Quantification remains one of the central challenges of effective Data Assimilation (DA) in complex partially observed non-linear systems. Stochastic parameterization methods have been proposed in recent years as a means of capturing the uncertainty associated with unresolved sub-grid scale processes. Such approaches generally require some knowledge of the true sub-grid scale process or rely on full observations of the larger scale resolved process. We present a methodology for estimating the statistics of sub-grid scale processes using only partial observations of the resolved process. It finds model error realisations over a training period by minimizing their conditional variance, constrained by available observations. Special is that these realisations are binned conditioned on the previous model state during the minimization process, allowing for the recovery of complex error structures. The efficacy of the approach is demonstrated through numerical experiments on the multi-scale Lorenz 96' model. We consider different parameterizations of the model with both small and large time scale separations between slow and fast variables. Results are compared to two existing methods for accounting for model uncertainty in DA and shown to provide improved analyses and forecasts.

On multilevel RBF collocation to solve nonlinear PDEs arising from endogenous stochastic volatility models

NASA Astrophysics Data System (ADS)

Bastani, Ali Foroush; Dastgerdi, Maryam Vahid; Mighani, Abolfazl

2018-06-01

The main aim of this paper is the analytical and numerical study of a time-dependent second-order nonlinear partial differential equation (PDE) arising from the endogenous stochastic volatility model, introduced in [Bensoussan, A., Crouhy, M. and Galai, D., Stochastic equity volatility related to the leverage effect (I): equity volatility behavior. Applied Mathematical Finance, 1, 63-85, 1994]. As the first step, we derive a consistent set of initial and boundary conditions to complement the PDE, when the firm is financed by equity and debt. In the sequel, we propose a Newton-based iteration scheme for nonlinear parabolic PDEs which is an extension of a method for solving elliptic partial differential equations introduced in [Fasshauer, G. E., Newton iteration with multiquadrics for the solution of nonlinear PDEs. Computers and Mathematics with Applications, 43, 423-438, 2002]. The scheme is based on multilevel collocation using radial basis functions (RBFs) to solve the resulting locally linearized elliptic PDEs obtained at each level of the Newton iteration. We show the effectiveness of the resulting framework by solving a prototypical example from the field and compare the results with those obtained from three different techniques: (1) a finite difference discretization; (2) a naive RBF collocation and (3) a benchmark approximation, introduced for the first time in this paper. The numerical results confirm the robustness, higher convergence rate and good stability properties of the proposed scheme compared to other alternatives. We also comment on some possible research directions in this field.

Antecedents of teachers’ emotions in the classroom: an intraindividual approach

PubMed Central

Becker, Eva S.; Keller, Melanie M.; Goetz, Thomas; Frenzel, Anne C.; Taxer, Jamie L.

2015-01-01

Using a preexisting, but as yet empirically untested theoretical model, the present study investigated antecedents of teachers’ emotions in the classroom. More specifically, the relationships between students’ motivation and discipline and teachers’ enjoyment and anger were explored, as well as if these relationships are mediated by teachers’ subjective appraisals (goal conduciveness and coping potential). The study employed an intraindividual approach by collecting data through a diary. The sample consisted of 39 teachers who each participated with one of their 9th or 10th grade mathematics classes (N = 758 students). Both teachers and students filled out diaries for 2–3 weeks pertaining to 8.10 lessons on average (N = 316 lessons). Multilevel structural equation modeling revealed that students’ motivation and discipline explained 24% of variance in teachers’ enjoyment and 26% of variance in teachers’ anger. In line with theoretical assumptions, after introducing teachers’ subjective appraisals as a mediating mechanism into the model, the explained variance systematically increased to 65 and 61%, for teachers’ enjoyment and anger respectively. The effects of students’ motivation and discipline level on teachers’ emotions were partially mediated by teachers’ appraisals of goal conduciveness and coping potential. The findings imply that since teachers’ emotions depend to a large extent on subjective evaluations of a situation, teachers should be able to directly modify their emotional experiences during a lesson through cognitive reappraisals. PMID:26042067

Validity of Futrex-5000 for body composition determination.

PubMed

McLean, K P; Skinner, J S

1992-02-01

Underwater weighing (UWW), skinfolds (SKF), and the Futrex-5000 (FTX) were compared by using UWW as the criterion measure of body fat in 30 male and 31 female Caucasians. Estimates of body fat (% fat) were obtained using The Y's Way to Fitness SKF equations and the standard FTX technique with near-infrared interactance (NIR) measured at the biceps, plus six sites for men and five sites for women. SKF correlated significantly higher with UWW than did FTX with UWW for males (0.95 vs 0.80), females (0.88 vs 0.63), and the whole group (0.94 vs 0.81). Fewer subjects (52%) were within +/- 4% of the UWW value using FTX, compared with 87% with SKF. FTX overestimated body fat in lean subjects with less than 8% fat and underestimated it in subjects with greater than 30% fat. Measuring NIR at additional sites did not improve the predicted variance. Partial F-tests indicate that using body mass index, instead of height and weight, in the FTX equation improved body fat prediction for females. Biceps NIR predicted additional variance in body fat beyond height, weight, frame size, and activity level but little variance above that predicted by these four variables plus SKF (2% more in males and less than 1% in females). Thus, SKF give more information and more accurately predict body fat, especially at the extremes of the body fat continuum.

Social cognitive predictors of first- and non-first-generation college students' academic and life satisfaction.

PubMed

Garriott, Patton O; Hudyma, Aaron; Keene, Chesleigh; Santiago, Dana

2015-04-01

The present study tested Lent's (2004) social-cognitive model of normative well-being in a sample (N = 414) of first- and non-first-generation college students. A model depicting relationships between: positive affect, environmental supports, college self-efficacy, college outcome expectations, academic progress, academic satisfaction, and life satisfaction was examined using structural equation modeling. The moderating roles of perceived importance of attending college and intrinsic goal motivation were also explored. Results suggested the hypothesized model provided an adequate fit to the data while hypothesized relationships in the model were partially supported. Environmental supports predicted college self-efficacy, college outcome expectations, and academic satisfaction. Furthermore, college self-efficacy predicted academic progress while college outcome expectations predicted academic satisfaction. Academic satisfaction, but not academic progress predicted life satisfaction. The structural model explained 44% of the variance in academic progress, 56% of the variance in academic satisfaction, and 28% of the variance in life satisfaction. Mediation analyses indicated several significant indirect effects between variables in the model while moderation analyses revealed a 3-way interaction between academic satisfaction, intrinsic motivation for attending college, and first-generation college student status on life satisfaction. Results are discussed in terms of applying the normative model of well-being to promote first- and non-first-generation college students' academic and life satisfaction. (c) 2015 APA, all rights reserved).

Sampling intraspecific variability in leaf functional traits: Practical suggestions to maximize collected information.

PubMed

Petruzzellis, Francesco; Palandrani, Chiara; Savi, Tadeja; Alberti, Roberto; Nardini, Andrea; Bacaro, Giovanni

2017-12-01

The choice of the best sampling strategy to capture mean values of functional traits for a species/population, while maintaining information about traits' variability and minimizing the sampling size and effort, is an open issue in functional trait ecology. Intraspecific variability (ITV) of functional traits strongly influences sampling size and effort. However, while adequate information is available about intraspecific variability between individuals (ITV BI ) and among populations (ITV POP ), relatively few studies have analyzed intraspecific variability within individuals (ITV WI ). Here, we provide an analysis of ITV WI of two foliar traits, namely specific leaf area (SLA) and osmotic potential (π), in a population of Quercus ilex L. We assessed the baseline ITV WI level of variation between the two traits and provided the minimum and optimal sampling size in order to take into account ITV WI , comparing sampling optimization outputs with those previously proposed in the literature. Different factors accounted for different amount of variance of the two traits. SLA variance was mostly spread within individuals (43.4% of the total variance), while π variance was mainly spread between individuals (43.2%). Strategies that did not account for all the canopy strata produced mean values not representative of the sampled population. The minimum size to adequately capture the studied functional traits corresponded to 5 leaves taken randomly from 5 individuals, while the most accurate and feasible sampling size was 4 leaves taken randomly from 10 individuals. We demonstrate that the spatial structure of the canopy could significantly affect traits variability. Moreover, different strategies for different traits could be implemented during sampling surveys. We partially confirm sampling sizes previously proposed in the recent literature and encourage future analysis involving different traits.

Sources of genetic and phenotypic variance in fertilization rates and larval traits in a sea urchin.

PubMed

Evans, Jonathan P; García-González, Francisco; Marshall, Dustin J

2007-12-01

In nonresource based mating systems females are thought to derive indirect genetic benefits by mating with high-quality males. Such benefits can be due either to the intrinsic genetic quality of sires or to beneficial interactions between maternal and paternal haplotypes. Animals with external fertilization and no parental care offer unrivaled opportunities to address these hypotheses. With these systems, cross-classified breeding designs and in vitro fertilization can be used to disentangle sources of genetic and environmental variance in offspring fitness. Here, we employ these approaches in the Australian sea urchin Heliocidaris erythrogramma and explore how sire-dam identities influence fertilization rates, embryo viability (survival to hatching), and metamorphosis, as well as the interrelationships between these potential fitness traits. We show that fertilization is influenced by a combination of strong maternal effects and intrinsic male effects. Our subsequent analysis of embryo viability, however, revealed a highly significant interaction between parental genotypes, indicating that partial incompatibilities can severely limit offspring survival at this life-history stage. Importantly, we detected no significant relationship between fertilization rates and embryo viability. This finding suggests that fertilization rates should not be inferred from hatching rates, which is commonly practiced in species in which it is not possible to estimate fertilization at conception. Finally, we detected significant additive genetic variance due to sires in rates of juvenile metamorphosis, and a positive correlation between fertilization rates and metamorphosis. This latter finding indicates that the performance of a male's ejaculate in noncompetitive IVF trials predicts heritable offspring traits, although the fitness implications of variance in rates of spontaneous juvenile metamorphosis have yet to be determined.

Ridding fMRI data of motion-related influences: Removal of signals with distinct spatial and physical bases in multiecho data.

PubMed

Power, Jonathan D; Plitt, Mark; Gotts, Stephen J; Kundu, Prantik; Voon, Valerie; Bandettini, Peter A; Martin, Alex

2018-02-27

"Functional connectivity" techniques are commonplace tools for studying brain organization. A critical element of these analyses is to distinguish variance due to neurobiological signals from variance due to nonneurobiological signals. Multiecho fMRI techniques are a promising means for making such distinctions based on signal decay properties. Here, we report that multiecho fMRI techniques enable excellent removal of certain kinds of artifactual variance, namely, spatially focal artifacts due to motion. By removing these artifacts, multiecho techniques reveal frequent, large-amplitude blood oxygen level-dependent (BOLD) signal changes present across all gray matter that are also linked to motion. These whole-brain BOLD signals could reflect widespread neural processes or other processes, such as alterations in blood partial pressure of carbon dioxide (pCO 2 ) due to ventilation changes. By acquiring multiecho data while monitoring breathing, we demonstrate that whole-brain BOLD signals in the resting state are often caused by changes in breathing that co-occur with head motion. These widespread respiratory fMRI signals cannot be isolated from neurobiological signals by multiecho techniques because they occur via the same BOLD mechanism. Respiratory signals must therefore be removed by some other technique to isolate neurobiological covariance in fMRI time series. Several methods for removing global artifacts are demonstrated and compared, and were found to yield fMRI time series essentially free of motion-related influences. These results identify two kinds of motion-associated fMRI variance, with different physical mechanisms and spatial profiles, each of which strongly and differentially influences functional connectivity patterns. Distance-dependent patterns in covariance are nearly entirely attributable to non-BOLD artifacts.

Memory is Not Enough: The Neurobiological Substrates of Dynamic Cognitive Reserve.

PubMed

Serra, Laura; Bruschini, Michela; Di Domenico, Carlotta; Gabrielli, Giulia Bechi; Marra, Camillo; Caltagirone, Carlo; Cercignani, Mara; Bozzali, Marco

2017-01-01

Changes in the residual memory variance are considered as a dynamic aspect of cognitive reserve (d-CR). We aimed to investigate for the first time the neural substrate associated with changes in the residual memory variance overtime in patients with amnestic mild cognitive impairment (aMCI). Thirty-four aMCI patients followed-up for 36 months and 48 healthy elderly individuals (HE) were recruited. All participants underwent 3T MRI, collecting T1-weighted images for voxel-based morphometry (VBM). They underwent an extensive neuropsychological battery, including six episodic memory tests. In patients and controls, factor analyses were used on the episodic memory scores to obtain a composite memory score (C-MS). Partial Least Square analyses were used to decompose the variance of C-MS in latent variables (LT scores), accounting for demographic variables and for the general cognitive efficiency level; linear regressions were applied on LT scores, striping off any contribution of general cognitive abilities, to obtain the residual value of memory variance, considered as an index of d-CR. LT scores and d-CR were used in discriminant analysis, in patients only. Finally, LT scores and d-CR were used as variable of interest in VBM analysis. The d-CR score was not able to correctly classify patients. In both aMCI patients and HE, LT1st and d-CR scores showed correlations with grey matter volumes in common and in specific brain areas. Using CR measures limited to assess memory function is likely less sensitive to detect the cognitive decline and predict the evolution of Alzheimer's disease. In conclusion, d-CR needs a measure of general cognition to identify conversion to Alzheimer's disease efficiently.

Analytical-Based Partial Volume Recovery in Mouse Heart Imaging

NASA Astrophysics Data System (ADS)

Dumouchel, Tyler; deKemp, Robert A.

2011-02-01

Positron emission tomography (PET) is a powerful imaging modality that has the ability to yield quantitative images of tracer activity. Physical phenomena such as photon scatter, photon attenuation, random coincidences and spatial resolution limit quantification potential and must be corrected to preserve the accuracy of reconstructed images. This study focuses on correcting the partial volume effects that arise in mouse heart imaging when resolution is insufficient to resolve the true tracer distribution in the myocardium. The correction algorithm is based on fitting 1D profiles through the myocardium in gated PET images to derive myocardial contours along with blood, background and myocardial activity. This information is interpolated onto a 2D grid and convolved with the tomograph's point spread function to derive regional recovery coefficients enabling partial volume correction. The point spread function was measured by placing a line source inside a small animal PET scanner. PET simulations were created based on noise properties measured from a reconstructed PET image and on the digital MOBY phantom. The algorithm can estimate the myocardial activity to within 5% of the truth when different wall thicknesses, backgrounds and noise properties are encountered that are typical of healthy FDG mouse scans. The method also significantly improves partial volume recovery in simulated infarcted tissue. The algorithm offers a practical solution to the partial volume problem without the need for co-registered anatomic images and offers a basis for improved quantitative 3D heart imaging.

Arthroscopic partial meniscectomy of a posteriorly flipped superior leaflet in a horizontal medial meniscus tear using a posterior transseptal portal.

PubMed

Jang, Ki-Mo; Ahn, Jin Hwan; Wang, Joon Ho

2012-03-07

This article describes a case of an arthroscopic partial meniscectomy of a posteriorly flipped superior leaflet in a horizontal medial meniscus tear using the posterior transseptal portal. An arthroscopic partial meniscectomy for bucket handle or flap tears in medial or lateral compartments using ordinary portals is a relatively common procedure in irreparable cases. However, the posterior compartment of the knee is not readily accessible through ordinary arthroscopic portals. Therefore, it has been considered a blind spot. Through the posterior transseptal portal, surgeons can achieve excellent arthroscopic visualization of the posterior compartment and easily perform arthroscopic procedures of the posterior compartment of the knee. A 48-year-old woman presented with a 1-year history of pain in the medial aspect of the right knee joint. Preoperative magnetic resonance imaging revealed a thinning of the medial meniscus posterior horn in coronal images and a sharp-edged triangle arising from the medial meniscus posterior horn between the medial femoral condyle and medial meniscus posterior horn on sagittal images (flipped-over sign). During the arthroscopic procedure, we found that the flipped leaflet was displaced posteriorly and was not mobile between the medial femoral condyle and medial meniscus posterior horn. Partial meniscectomy for a posteriorly displaced fragment can be performed successfully using the posterior transseptal portal. The posterior transseptal portal is useful for an arthroscopic partial meniscectomy of a posteriorly flipped leaflet in the posterior compartment of the knee. Copyright 2012, SLACK Incorporated.

Safety of Onyx Transarterial Embolization of Skull Base Dural Arteriovenous Fistulas from Meningeal Branches of the External Carotids also Fed by Meningeal Branches of Internal Carotid or Vertebral Arteries.

PubMed

Abud, Thiago G; Houdart, Emmanuel; Saint-Maurice, Jean-Pierre; Abud, Daniel G; Baccin, Carlos E; Nguyen, Andrew D; Abdala, Nitamar

2017-08-11

To analyze the angiographic and clinical results of transarterial embolization with Onyx (Medtronic-Covidien, Irvine, CA) in dural arteriovenous fistulas (DAVFs) partially fed by arteries arising from the carotid siphon or the vertebral arteries. We isolated 40 DAVFs supplied by either the tentorial artery of the internal carotid artery (ICA) or the posterior meningeal artery of the vertebral artery. These DAVFs were embolized with Onyx through the middle meningeal artery or the occipital artery. We reviewed the occurrence of reflux into the arteries of carotid or vertebral origin. In all the cases, reflux occurred into the first millimeters of the DAVF arterial feeders arising from carotid or vertebral arteries but slowly enough to be controlled by interruption of Onyx injection. Reflux was always minimal and Onyx never reached the ostium of the arteries. No cerebral ischemic complications occurred in our series. The behavior of Onyx is clearly different from that of cyanoacrylate glue, resulting in superior control during injection. Reflux into arteries arising from the ICA or vertebral artery during DAVF treatment always carries a risk of unintentional non-target embolization of normal cerebral vasculature but Onyx appears to be safe in this situation.

Encoding processes during retrieval tasks.

PubMed

Buckner, R L; Wheeler, M E; Sheridan, M A

2001-04-01

Episodic memory encoding is pervasive across many kinds of task and often arises as a secondary processing effect in tasks that do not require intentional memorization. To illustrate the pervasive nature of information processing that leads to episodic encoding, a form of incidental encoding was explored based on the "Testing" phenomenon: The incidental-encoding task was an episodic memory retrieval task. Behavioral data showed that performing a memory retrieval task was as effective as intentional instructions at promoting episodic encoding. During fMRI imaging, subjects viewed old and new words and indicated whether they remembered them. Relevant to encoding, the fate of the new words was examined using a second, surprise test of recognition after the imaging session. fMRI analysis of those new words that were later remembered revealed greater activity in left frontal regions than those that were later forgotten - the same pattern of results as previously observed for traditional incidental and intentional episodic encoding tasks. This finding may offer a partial explanation for why repeated testing improves memory performance. Furthermore, the observation of correlates of episodic memory encoding during retrieval tasks challenges some interpretations that arise from direct comparisons between "encoding tasks" and "retrieval tasks" in imaging data. Encoding processes and their neural correlates may arise in many tasks, even those nominally labeled as retrieval tasks by the experimenter.

Variable horizon in a peridynamic medium

DOE PAGES

Silling, Stewart A.; Littlewood, David J.; Seleson, Pablo

2015-12-10

Here, a notion of material homogeneity is proposed for peridynamic bodies with variable horizon but constant bulk properties. A relation is derived that scales the force state according to the position-dependent horizon while keeping the bulk properties unchanged. Using this scaling relation, if the horizon depends on position, artifacts called ghost forces may arise in a body under a homogeneous deformation. These artifacts depend on the second derivative of the horizon and can be reduced by employing a modified equilibrium equation using a new quantity called the partial stress. Bodies with piecewise constant horizon can be modeled without ghost forcesmore » by using a simpler technique called a splice. As a limiting case of zero horizon, both the partial stress and splice techniques can be used to achieve local-nonlocal coupling. Computational examples, including dynamic fracture in a one-dimensional model with local-nonlocal coupling, illustrate the methods.« less

A partial Hamiltonian approach for current value Hamiltonian systems

NASA Astrophysics Data System (ADS)

Naz, R.; Mahomed, F. M.; Chaudhry, Azam

2014-10-01

We develop a partial Hamiltonian framework to obtain reductions and closed-form solutions via first integrals of current value Hamiltonian systems of ordinary differential equations (ODEs). The approach is algorithmic and applies to many state and costate variables of the current value Hamiltonian. However, we apply the method to models with one control, one state and one costate variable to illustrate its effectiveness. The current value Hamiltonian systems arise in economic growth theory and other economic models. We explain our approach with the help of a simple illustrative example and then apply it to two widely used economic growth models: the Ramsey model with a constant relative risk aversion (CRRA) utility function and Cobb Douglas technology and a one-sector AK model of endogenous growth are considered. We show that our newly developed systematic approach can be used to deduce results given in the literature and also to find new solutions.

A preconditioner for the finite element computation of incompressible, nonlinear elastic deformations

NASA Astrophysics Data System (ADS)

Whiteley, J. P.

2017-10-01

Large, incompressible elastic deformations are governed by a system of nonlinear partial differential equations. The finite element discretisation of these partial differential equations yields a system of nonlinear algebraic equations that are usually solved using Newton's method. On each iteration of Newton's method, a linear system must be solved. We exploit the structure of the Jacobian matrix to propose a preconditioner, comprising two steps. The first step is the solution of a relatively small, symmetric, positive definite linear system using the preconditioned conjugate gradient method. This is followed by a small number of multigrid V-cycles for a larger linear system. Through the use of exemplar elastic deformations, the preconditioner is demonstrated to facilitate the iterative solution of the linear systems arising. The number of GMRES iterations required has only a very weak dependence on the number of degrees of freedom of the linear systems.

Stochastic partial differential fluid equations as a diffusive limit of deterministic Lagrangian multi-time dynamics

PubMed Central

Cotter, C. J.

2017-01-01

In Holm (Holm 2015 Proc. R. Soc. A 471, 20140963. (doi:10.1098/rspa.2014.0963)), stochastic fluid equations were derived by employing a variational principle with an assumed stochastic Lagrangian particle dynamics. Here we show that the same stochastic Lagrangian dynamics naturally arises in a multi-scale decomposition of the deterministic Lagrangian flow map into a slow large-scale mean and a rapidly fluctuating small-scale map. We employ homogenization theory to derive effective slow stochastic particle dynamics for the resolved mean part, thereby obtaining stochastic fluid partial equations in the Eulerian formulation. To justify the application of rigorous homogenization theory, we assume mildly chaotic fast small-scale dynamics, as well as a centring condition. The latter requires that the mean of the fluctuating deviations is small, when pulled back to the mean flow. PMID:28989316

Evaluation of Nd:YAG laser on partial oxygen saturation of pulpal blood in anterior hypersensitive teeth.

PubMed

Birang, Reza; Kaviani, Naser; Mohammadpour, Mehdi; Abed, Ahmad Moghareh; Gutknecht, Norbert; Mir, Maziar

2008-07-01

Dentine hypersensitivity has of long been known to be a common clinical problem in dental practices. Lasers have recently come to play a prominent role in the treatment of this disorder. They might, however, cause dental pulp damage. This study was conducted to evaluate the effect of Nd:yttrium-aluminum-garnet (YAG) laser on partial oxygen saturation of pulpal blood in sensitive anterior teeth. In this clinical trial, 65 hypersensitive teeth were selected and randomly allocated to two groups. The study group involved Nd:YAG laser treatment, while no treatment was employed for the control group. Using a pulse oximetry system, evaluations were preformed of the partial oxygen saturation in the pulpal blood before, immediately after, 1 week after, and 1 month after the treatment. The results were analyzed using the SPSS software and repeated-measures analysis of variance and paired-samples t tests. The mean partial oxygen saturation of the blood was found to be 85.4% in the study group, which was not significantly different from that of the control group. No significant differences were observed in the control group between the means obtained from pretreatment and post-treatment intervals (P > 0.05). The Post-treatment partial oxygen saturation mean rose to 89.3% (P = 0.001) and remained constant throughout the following week after it. However, no significant differences were found between the pretreatment partial oxygen saturation mean and the same measurement 1 month after treatment (P = 0.702). Nd:YAG laser therapy for dentine desensitization of anterior teeth caused no persistent changes in the partial oxygen saturation of pulpal blood. It may, therefore, be concluded that the diffusion of heat induced by the Nd:YAG laser into the pulp within the limit of the desensitization parameters cause no irreversible damages in the dental pulp.

Approaches to characterise chromatographic column performance based on global parameters accounting for peak broadening and skewness.

PubMed

Baeza-Baeza, J J; Pous-Torres, S; Torres-Lapasió, J R; García-Alvarez-Coque, M C

2010-04-02

Peak broadening and skewness are fundamental parameters in chromatography, since they affect the resolution capability of a chromatographic column. A common practice to characterise chromatographic columns is to estimate the efficiency and asymmetry factor for the peaks of one or more solutes eluted at selected experimental conditions. This has the drawback that the extra-column contributions to the peak variance and skewness make the peak shape parameters depend on the retention time. We propose and discuss here the use of several approaches that allow the estimation of global parameters (non-dependent on the retention time) to describe the column performance. The global parameters arise from different linear relationships that can be established between the peak variance, standard deviation, or half-widths with the retention time. Some of them describe exclusively the column contribution to the peak broadening, whereas others consider the extra-column effects also. The estimation of peak skewness was also possible for the approaches based on the half-widths. The proposed approaches were applied to the characterisation of different columns (Spherisorb, Zorbax SB, Zorbax Eclipse, Kromasil, Chromolith, X-Terra and Inertsil), using the chromatographic data obtained for several diuretics and basic drugs (beta-blockers). Copyright (c) 2010 Elsevier B.V. All rights reserved.

Genetic divergence of the seminal signal-receptor system in houseflies: the footprints of sexually antagonistic coevolution?

PubMed

Andrés, J A; Arnqvist, G

2001-02-22

To understand fully the significance of cryptic female choice, we need to focus on each of those postmating processes in females which create variance in fitness among males. Earlier studies have focused almost exclusively on the proportion of a female's eggs fertilized by different males (sperm precedence). Yet, variance in male postmating reproductive success may also arise from differences in ability to stimulate female oviposition and to delay female remating. Here, we present a series of reciprocal mating experiments among genetically differentiated wild-type strains of the housefly Musca domestica. We compared the effects of male and female genotype on oviposition and remating by females. The genotype of each sex affected both female oviposition and remating rates, demonstrating that the signal-receptor system involved has indeed diverged among these strains. Further, there was a significant interaction between the effects of male and female genotype on oviposition rate. We discuss ways in which the pattern of such interactions provides insights into the coevolutionary mechanism involved. Females in our experiments generally exhibited the weakest, rather than the strongest, response to males with which they are coevolved. These results support the hypothesis that coevolution of male seminal signals and female receptors is sexually antagonistic.

The Role of Graphlets in Viral Processes on Networks

NASA Astrophysics Data System (ADS)

Khorshidi, Samira; Al Hasan, Mohammad; Mohler, George; Short, Martin B.

2018-05-01

Predicting the evolution of viral processes on networks is an important problem with applications arising in biology, the social sciences, and the study of the Internet. In existing works, mean-field analysis based upon degree distribution is used for the prediction of viral spreading across networks of different types. However, it has been shown that degree distribution alone fails to predict the behavior of viruses on some real-world networks and recent attempts have been made to use assortativity to address this shortcoming. In this paper, we show that adding assortativity does not fully explain the variance in the spread of viruses for a number of real-world networks. We propose using the graphlet frequency distribution in combination with assortativity to explain variations in the evolution of viral processes across networks with identical degree distribution. Using a data-driven approach by coupling predictive modeling with viral process simulation on real-world networks, we show that simple regression models based on graphlet frequency distribution can explain over 95% of the variance in virality on networks with the same degree distribution but different network topologies. Our results not only highlight the importance of graphlets but also identify a small collection of graphlets which may have the highest influence over the viral processes on a network.

Factor structure of the happiness-increasing strategies scales (H-ISS): activities and coping strategies in relation to positive and negative affect.

PubMed

Al Nima, Ali; Garcia, Danilo

2015-01-01

Background. Previous research (Tkach & Lyubomirsky, 2006) shows that there are eight general happiness-increasing strategies: social affiliation, partying, mental control, goal pursuit, passive leisure, active leisure, religion, and direct attempts. The present study investigates the factor structure of the happiness-increasing strategies scales (H-ISS) and their relationship to positive and negative affect. Method. The present study used participants' (N = 1,050 and age mean = 34.21 sd = 12.73) responses to the H-ISS in structural equation modeling analyses. Affect was measured using the Positive Affect Negative Affect Schedule. Results. After small modifications we obtained a good model that contains the original eight factors/scales. Moreover, we found that women tend to use social affiliation, mental control, passive leisure, religion, and direct attempts more than men, while men preferred to engage in partying and clubbing more than women. The H-ISS explained significantly the variance of positive affect (R (2) = .41) and the variance of negative affect (R (2) = .27). Conclusions. Our study is an addition to previous research showing that the factor structure of the happiness-increasing strategies is valid and reliable. However, due to the model fitting issues that arise in the present study, we give some suggestions for improving the instrument.

Powerful Statistical Inference for Nested Data Using Sufficient Summary Statistics

PubMed Central

Dowding, Irene; Haufe, Stefan

2018-01-01

Hierarchically-organized data arise naturally in many psychology and neuroscience studies. As the standard assumption of independent and identically distributed samples does not hold for such data, two important problems are to accurately estimate group-level effect sizes, and to obtain powerful statistical tests against group-level null hypotheses. A common approach is to summarize subject-level data by a single quantity per subject, which is often the mean or the difference between class means, and treat these as samples in a group-level t-test. This “naive” approach is, however, suboptimal in terms of statistical power, as it ignores information about the intra-subject variance. To address this issue, we review several approaches to deal with nested data, with a focus on methods that are easy to implement. With what we call the sufficient-summary-statistic approach, we highlight a computationally efficient technique that can improve statistical power by taking into account within-subject variances, and we provide step-by-step instructions on how to apply this approach to a number of frequently-used measures of effect size. The properties of the reviewed approaches and the potential benefits over a group-level t-test are quantitatively assessed on simulated data and demonstrated on EEG data from a simulated-driving experiment. PMID:29615885

Genetic drift and collective dispersal can result in chaotic genetic patchiness.

PubMed

Broquet, Thomas; Viard, Frédérique; Yearsley, Jonathan M

2013-06-01

Chaotic genetic patchiness denotes unexpected patterns of genetic differentiation that are observed at a fine scale and are not stable in time. These patterns have been described in marine species with free-living larvae, but are unexpected because they occur at a scale below the dispersal range of pelagic larvae. At the scale where most larvae are immigrants, theory predicts spatially homogeneous, temporally stable genetic variation. Empirical studies have suggested that genetic drift interacts with complex dispersal patterns to create chaotic genetic patchiness. Here we use a co-ancestry model and individual-based simulations to test this idea. We found that chaotic genetic patterns (qualified by global FST and spatio-temporal variation in FST's between pairs of samples) arise from the combined effects of (1) genetic drift created by the small local effective population sizes of the sessile phase and variance in contribution among breeding groups and (2) collective dispersal of related individuals in the larval phase. Simulations show that patchiness levels qualitatively comparable to empirical results can be produced by a combination of strong variance in reproductive success and mild collective dispersal. These results call for empirical studies of the effective number of breeders producing larval cohorts, and population genetics at the larval stage. © 2012 The Author(s). Evolution © 2012 The Society for the Study of Evolution.

Growth models and the expected distribution of fluctuating asymmetry

USGS Publications Warehouse

Graham, John H.; Shimizu, Kunio; Emlen, John M.; Freeman, D. Carl; Merkel, John

2003-01-01

Multiplicative error accounts for much of the size-scaling and leptokurtosis in fluctuating asymmetry. It arises when growth involves the addition of tissue to that which is already present. Such errors are lognormally distributed. The distribution of the difference between two lognormal variates is leptokurtic. If those two variates are correlated, then the asymmetry variance will scale with size. Inert tissues typically exhibit additive error and have a gamma distribution. Although their asymmetry variance does not exhibit size-scaling, the distribution of the difference between two gamma variates is nevertheless leptokurtic. Measurement error is also additive, but has a normal distribution. Thus, the measurement of fluctuating asymmetry may involve the mixing of additive and multiplicative error. When errors are multiplicative, we recommend computing log E(l) − log E(r), the difference between the logarithms of the expected values of left and right sides, even when size-scaling is not obvious. If l and r are lognormally distributed, and measurement error is nil, the resulting distribution will be normal, and multiplicative error will not confound size-related changes in asymmetry. When errors are additive, such a transformation to remove size-scaling is unnecessary. Nevertheless, the distribution of l − r may still be leptokurtic.

Grey matter networks in people at increased familial risk for schizophrenia.

PubMed

Tijms, Betty M; Sprooten, Emma; Job, Dominic; Johnstone, Eve C; Owens, David G C; Willshaw, David; Seriès, Peggy; Lawrie, Stephen M

2015-10-01

Grey matter brain networks are disrupted in schizophrenia, but it is still unclear at which point during the development of the illness these disruptions arise and whether these can be associated with behavioural predictors of schizophrenia. We investigated if single-subject grey matter networks were disrupted in a sample of people at familial risk of schizophrenia. Single-subject grey matter networks were extracted from structural MRI scans of 144 high risk subjects, 32 recent-onset patients and 36 healthy controls. The following network properties were calculated: size, connectivity density, degree, path length, clustering coefficient, betweenness centrality and small world properties. People at risk of schizophrenia showed decreased path length and clustering in mostly prefrontal and temporal areas. Within the high risk sample, the path length of the posterior cingulate cortex and the betweenness centrality of the left inferior frontal operculum explained 81% of the variance in schizotypal cognitions, which was previously shown to be the strongest behavioural predictor of schizophrenia in the study. In contrast, local grey matter volume measurements explained 48% of variance in schizotypy. The present results suggest that single-subject grey matter networks can quantify behaviourally relevant biological alterations in people at increased risk for schizophrenia before disease onset. Copyright © 2015 Elsevier B.V. All rights reserved.

On the motion of classical three-body system with consideration of quantum fluctuations

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

Gevorkyan, A. S., E-mail: g-ashot@sci.am

2017-03-15

We obtained the systemof stochastic differential equations which describes the classicalmotion of the three-body system under influence of quantum fluctuations. Using SDEs, for the joint probability distribution of the total momentum of bodies system were obtained the partial differential equation of the second order. It is shown, that the equation for the probability distribution is solved jointly by classical equations, which in turn are responsible for the topological peculiarities of tubes of quantum currents, transitions between asymptotic channels and, respectively for arising of quantum chaos.

Analysis of wavelet technology for NASA applications

NASA Technical Reports Server (NTRS)

Wells, R. O., Jr.

1994-01-01

The purpose of this grant was to introduce a broad group of NASA researchers and administrators to wavelet technology and to determine its future role in research and development at NASA JSC. The activities of several briefings held between NASA JSC scientists and Rice University researchers are discussed. An attached paper, 'Recent Advances in Wavelet Technology', summarizes some aspects of these briefings. Two proposals submitted to NASA reflect the primary areas of common interest. They are image analysis and numerical solutions of partial differential equations arising in computational fluid dynamics and structural mechanics.

Entropic inequalities for a class of quantum secret-sharing states

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

Sarvepalli, Pradeep

It is well known that von Neumann entropy is nonmonotonic, unlike Shannon entropy (which is monotonically nondecreasing). Consequently, it is difficult to relate the entropies of the subsystems of a given quantum state. In this paper, we show that if we consider quantum secret-sharing states arising from a class of monotone span programs, then we can partially recover the monotonicity of entropy for the so-called unauthorized sets. Furthermore, we can show for these quantum states that the entropy of the authorized sets is monotonically nonincreasing.

Sexually antagonistic selection on genetic variation underlying both male and female same-sex sexual behavior.

PubMed

Berger, David; You, Tao; Minano, Maravillas R; Grieshop, Karl; Lind, Martin I; Arnqvist, Göran; Maklakov, Alexei A

2016-05-13

Intralocus sexual conflict, arising from selection for different alleles at the same locus in males and females, imposes a constraint on sex-specific adaptation. Intralocus sexual conflict can be alleviated by the evolution of sex-limited genetic architectures and phenotypic expression, but pleiotropic constraints may hinder this process. Here, we explored putative intralocus sexual conflict and genetic (co)variance in a poorly understood behavior with near male-limited expression. Same-sex sexual behaviors (SSBs) generally do not conform to classic evolutionary models of adaptation but are common in male animals and have been hypothesized to result from perception errors and selection for high male mating rates. However, perspectives incorporating sex-specific selection on genes shared by males and females to explain the expression and evolution of SSBs have largely been neglected. We performed two parallel sex-limited artificial selection experiments on SSB in male and female seed beetles, followed by sex-specific assays of locomotor activity and male sex recognition (two traits hypothesized to be functionally related to SSB) and adult reproductive success (allowing us to assess fitness consequences of genetic variance in SSB and its correlated components). Our experiments reveal both shared and sex-limited genetic variance for SSB. Strikingly, genetically correlated responses in locomotor activity and male sex-recognition were associated with sexually antagonistic fitness effects, but these effects differed qualitatively between male and female selection lines, implicating intralocus sexual conflict at both male- and female-specific genetic components underlying SSB. Our study provides experimental support for the hypothesis that widespread pleiotropy generates pervasive intralocus sexual conflict governing the expression of SSBs, suggesting that SSB in one sex can occur due to the expression of genes that carry benefits in the other sex.

Additive genetic variance and developmental plasticity in growth trajectories in a wild cooperative mammal.

PubMed

Huchard, E; Charmantier, A; English, S; Bateman, A; Nielsen, J F; Clutton-Brock, T

2014-09-01

Individual variation in growth is high in cooperative breeders and may reflect plastic divergence in developmental trajectories leading to breeding vs. helping phenotypes. However, the relative importance of additive genetic variance and developmental plasticity in shaping growth trajectories is largely unknown in cooperative vertebrates. This study exploits weekly sequences of body mass from birth to adulthood to investigate sources of variance in, and covariance between, early and later growth in wild meerkats (Suricata suricatta), a cooperative mongoose. Our results indicate that (i) the correlation between early growth (prior to nutritional independence) and adult mass is positive but weak, and there are frequent changes (compensatory growth) in post-independence growth trajectories; (ii) among parameters describing growth trajectories, those describing growth rate (prior to and at nutritional independence) show undetectable heritability while associated size parameters (mass at nutritional independence and asymptotic mass) are moderately heritable (0.09 ≤ h(2) < 0.3); and (iii) additive genetic effects, rather than early environmental effects, mediate the covariance between early growth and adult mass. These results reveal that meerkat growth trajectories remain plastic throughout development, rather than showing early and irreversible divergence, and that the weak effects of early growth on adult mass, an important determinant of breeding success, are partly genetic. In contrast to most cooperative invertebrates, the acquisition of breeding status is often determined after sexual maturity and strongly impacted by chance in many cooperative vertebrates, who may therefore retain the ability to adjust their morphology to environmental changes and social opportunities arising throughout their development, rather than specializing early. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

Modeling conflict and error in the medial frontal cortex.

PubMed

Mayer, Andrew R; Teshiba, Terri M; Franco, Alexandre R; Ling, Josef; Shane, Matthew S; Stephen, Julia M; Jung, Rex E

2012-12-01

Despite intensive study, the role of the dorsal medial frontal cortex (dMFC) in error monitoring and conflict processing remains actively debated. The current experiment manipulated conflict type (stimulus conflict only or stimulus and response selection conflict) and utilized a novel modeling approach to isolate error and conflict variance during a multimodal numeric Stroop task. Specifically, hemodynamic response functions resulting from two statistical models that either included or isolated variance arising from relatively few error trials were directly contrasted. Twenty-four participants completed the task while undergoing event-related functional magnetic resonance imaging on a 1.5-Tesla scanner. Response times monotonically increased based on the presence of pure stimulus or stimulus and response selection conflict. Functional results indicated that dMFC activity was present during trials requiring response selection and inhibition of competing motor responses, but absent during trials involving pure stimulus conflict. A comparison of the different statistical models suggested that relatively few error trials contributed to a disproportionate amount of variance (i.e., activity) throughout the dMFC, but particularly within the rostral anterior cingulate gyrus (rACC). Finally, functional connectivity analyses indicated that an empirically derived seed in the dorsal ACC/pre-SMA exhibited strong connectivity (i.e., positive correlation) with prefrontal and inferior parietal cortex but was anti-correlated with the default-mode network. An empirically derived seed from the rACC exhibited the opposite pattern, suggesting that sub-regions of the dMFC exhibit different connectivity patterns with other large scale networks implicated in internal mentations such as daydreaming (default-mode) versus the execution of top-down attentional control (fronto-parietal). Copyright © 2011 Wiley Periodicals, Inc.

Minimizing the Standard Deviation of Spatially Averaged Surface Cross-Sectional Data from the Dual-Frequency Precipitation Radar

NASA Technical Reports Server (NTRS)

Meneghini, Robert; Kim, Hyokyung

2016-01-01

For an airborne or spaceborne radar, the precipitation-induced path attenuation can be estimated from the measurements of the normalized surface cross section, sigma 0, in the presence and absence of precipitation. In one implementation, the mean rain-free estimate and its variability are found from a lookup table (LUT) derived from previously measured data. For the dual-frequency precipitation radar aboard the global precipitation measurement satellite, the nominal table consists of the statistics of the rain-free 0 over a 0.5 deg x 0.5 deg latitude-longitude grid using a three-month set of input data. However, a problem with the LUT is an insufficient number of samples in many cells. An alternative table is constructed by a stepwise procedure that begins with the statistics over a 0.25 deg x 0.25 deg grid. If the number of samples at a cell is too few, the area is expanded, cell by cell, choosing at each step that cell that minimizes the variance of the data. The question arises, however, as to whether the selected region corresponds to the smallest variance. To address this question, a second type of variable-averaging grid is constructed using all possible spatial configurations and computing the variance of the data within each region. Comparisons of the standard deviations for the fixed and variable-averaged grids are given as a function of incidence angle and surface type using a three-month set of data. The advantage of variable spatial averaging is that the average standard deviation can be reduced relative to the fixed grid while satisfying the minimum sample requirement.

Statistics of the epoch of reionization 21-cm signal - I. Power spectrum error-covariance

NASA Astrophysics Data System (ADS)

Mondal, Rajesh; Bharadwaj, Somnath; Majumdar, Suman

2016-02-01

The non-Gaussian nature of the epoch of reionization (EoR) 21-cm signal has a significant impact on the error variance of its power spectrum P(k). We have used a large ensemble of seminumerical simulations and an analytical model to estimate the effect of this non-Gaussianity on the entire error-covariance matrix {C}ij. Our analytical model shows that {C}ij has contributions from two sources. One is the usual variance for a Gaussian random field which scales inversely of the number of modes that goes into the estimation of P(k). The other is the trispectrum of the signal. Using the simulated 21-cm Signal Ensemble, an ensemble of the Randomized Signal and Ensembles of Gaussian Random Ensembles we have quantified the effect of the trispectrum on the error variance {C}II. We find that its relative contribution is comparable to or larger than that of the Gaussian term for the k range 0.3 ≤ k ≤ 1.0 Mpc-1, and can be even ˜200 times larger at k ˜ 5 Mpc-1. We also establish that the off-diagonal terms of {C}ij have statistically significant non-zero values which arise purely from the trispectrum. This further signifies that the error in different k modes are not independent. We find a strong correlation between the errors at large k values (≥0.5 Mpc-1), and a weak correlation between the smallest and largest k values. There is also a small anticorrelation between the errors in the smallest and intermediate k values. These results are relevant for the k range that will be probed by the current and upcoming EoR 21-cm experiments.

Long-Term Behavior of Simulated Partial Lead Service Line Replacements

PubMed Central

St. Clair, Justin; Cartier, Clement; Triantafyllidou, Simoni; Clark, Brandi; Edwards, Marc

2016-01-01

Abstract In this 48-month pilot study, long-term impacts of copper:lead galvanic connections on lead release to water were assessed without confounding differences in pipe exposure prehistory or disturbances arising from cutting lead pipe. Lead release was tracked from three lead service line configurations, including (1) 100% lead, (2) traditional partial replacement with 50% copper upstream of 50% lead, and (3) 50% lead upstream of 50% copper as a function of flow rate, connection types, and sampling methodologies. Elevated lead from galvanic corrosion worsened with time, with 140% more lead release from configurations representing traditional partial replacement configurations at 14 months compared to earlier data in the first 8 months. Even when sampled consistently at moderate flow rate (8 LPM) and collecting all water passing through service lines, conditions representing traditional partial service line configurations were significantly worse (≈40%) when compared to 100% lead pipe. If sampled at a high flow rate (32 LPM) and collecting 2 L samples from service lines, 100% of samples collected from traditional partial replacement configurations exceeded thresholds posing an acute health risk versus a 0% risk for samples from 100% lead pipe. Temporary removal of lead accumulations near Pb:Cu junctions and lead deposits from other downstream plastic pipes reduced risk of partial replacements relative to that observed for 100% lead. When typical brass compression couplings were used to connect prepassivated lead pipes, lead release spiked up to 10 times higher, confirming prior concerns raised at bench and field scale regarding adverse impacts of crevices and service line disturbances on lead release. To quantify semirandom particulate lead release from service lines in future research, whole-house filters have many advantages compared to other approaches. PMID:26989344

A stabilized element-based finite volume method for poroelastic problems

NASA Astrophysics Data System (ADS)

Honório, Hermínio T.; Maliska, Clovis R.; Ferronato, Massimiliano; Janna, Carlo

2018-07-01

The coupled equations of Biot's poroelasticity, consisting of stress equilibrium and fluid mass balance in deforming porous media, are numerically solved. The governing partial differential equations are discretized by an Element-based Finite Volume Method (EbFVM), which can be used in three dimensional unstructured grids composed of elements of different types. One of the difficulties for solving these equations is the numerical pressure instability that can arise when undrained conditions take place. In this paper, a stabilization technique is developed to overcome this problem by employing an interpolation function for displacements that considers also the pressure gradient effect. The interpolation function is obtained by the so-called Physical Influence Scheme (PIS), typically employed for solving incompressible fluid flows governed by the Navier-Stokes equations. Classical problems with analytical solutions, as well as three-dimensional realistic cases are addressed. The results reveal that the proposed stabilization technique is able to eliminate the spurious pressure instabilities arising under undrained conditions at a low computational cost.

Male breast cancer arising in ectopic axillary breast tissue: A diagnostic dilemma.

PubMed

Xie, Yangchun; Huang, Jin; Xiao, Desheng; Zhong, Meizuo

2013-06-01

Male breast cancer arising in ectopic axillary breast tissue is a rare occurrence and few cases have been reported in the literature. Due to its rarity, male axillary breast cancer is easy to misdiagnose. As for adenocarcinoma in the axilla, it is difficult to identify whether the origin is the mammary tissue or the skin appendages, particularly in cases where there is a poor differentiation. The present study reports the case of a male patient with a right axillary lesion that had been present for 6 months. A histological evaluation revealed the features of a poorly-differentiated adenocarcinoma with regards to the pathological report. The patient was diagnosed with a metastatic adenocarcinoma with unknown primary origin. However, following 4 cycles of intensive chemotherapy, the patient experienced bone metastasis while the local lesion was in partial remission. Further immunohistochemistry confirmed its mammary origin. There is limited literature relating to male ectopic axillary breast cancer, and a high probability of misdiagnosis of this disease.

Male breast cancer arising in ectopic axillary breast tissue: A diagnostic dilemma

PubMed Central

XIE, YANGCHUN; HUANG, JIN; XIAO, DESHENG; ZHONG, MEIZUO

2013-01-01

Male breast cancer arising in ectopic axillary breast tissue is a rare occurrence and few cases have been reported in the literature. Due to its rarity, male axillary breast cancer is easy to misdiagnose. As for adenocarcinoma in the axilla, it is difficult to identify whether the origin is the mammary tissue or the skin appendages, particularly in cases where there is a poor differentiation. The present study reports the case of a male patient with a right axillary lesion that had been present for 6 months. A histological evaluation revealed the features of a poorly-differentiated adenocarcinoma with regards to the pathological report. The patient was diagnosed with a metastatic adenocarcinoma with unknown primary origin. However, following 4 cycles of intensive chemotherapy, the patient experienced bone metastasis while the local lesion was in partial remission. Further immunohistochemistry confirmed its mammary origin. There is limited literature relating to male ectopic axillary breast cancer, and a high probability of misdiagnosis of this disease. PMID:23833669

Final Report: Subcontract B623868 Algebraic Multigrid solvers for coupled PDE systems

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

Brannick, J.

The Pennsylvania State University (“Subcontractor”) continued to work on the design of algebraic multigrid solvers for coupled systems of partial differential equations (PDEs) arising in numerical modeling of various applications, with a main focus on solving the Dirac equation arising in Quantum Chromodynamics (QCD). The goal of the proposed work was to develop combined geometric and algebraic multilevel solvers that are robust and lend themselves to efficient implementation on massively parallel heterogeneous computers for these QCD systems. The research in these areas built on previous works, focusing on the following three topics: (1) the development of parallel full-multigrid (PFMG) andmore » non-Galerkin coarsening techniques in this frame work for solving the Wilson Dirac system; (2) the use of these same Wilson MG solvers for preconditioning the Overlap and Domain Wall formulations of the Dirac equation; and (3) the design and analysis of algebraic coarsening algorithms for coupled PDE systems including Stokes equation, Maxwell equation and linear elasticity.« less

A 12-week pilot study of acceptance of a computer-based chronic disease self-monitoring system among patients with type 2 diabetes mellitus and/or hypertension.

PubMed

Yan, Mian; Or, Calvin

2017-08-01

This study tested a structural model examining the effects of perceived usefulness, perceived ease of use, attitude, subjective norm, perceived behavioral control, health consciousness, and application-specific self-efficacy on the acceptance (i.e. behavioral intention and actual usage) of a computer-based chronic disease self-monitoring system among patients with type 2 diabetes mellitus and/or hypertension. The model was tested using partial least squares structural equation modeling, with 119 observations that were obtained by pooling data across three time points over a 12-week period. The results indicate that all of the seven constructs examined had a significant total effect on behavioral intention and explained 74 percent of the variance. Also, application-specific self-efficacy and behavioral intention had a significant total effect on actual usage and explained 17 percent of the variance. This study demonstrates that technology acceptance is determined by patient characteristics, technology attributes, and social influences. Applying the findings may increase the likelihood of acceptance.

The Riemann-Lanczos equations in general relativity and their integrability

NASA Astrophysics Data System (ADS)

Dolan, P.; Gerber, A.

2008-06-01

The aim of this paper is to examine the Riemann-Lanczos equations and how they can be made integrable. They consist of a system of linear first-order partial differential equations that arise in general relativity, whereby the Riemann curvature tensor is generated by an unknown third-order tensor potential field called the Lanczos tensor. Our approach is based on the theory of jet bundles, where all field variables and all their partial derivatives of all relevant orders are treated as independent variables alongside the local manifold coordinates (xa) on the given space-time manifold M. This approach is adopted in (a) Cartan's method of exterior differential systems, (b) Vessiot's dual method using vector field systems, and (c) the Janet-Riquier theory of systems of partial differential equations. All three methods allow for the most general situations under which integrability conditions can be found. They give equivalent results, namely, that involutivity is always achieved at all generic points of the jet manifold M after a finite number of prolongations. Two alternative methods that appear in the general relativity literature to find integrability conditions for the Riemann-Lanczos equations generate new partial differential equations for the Lanczos potential that introduce a source term, which is nonlinear in the components of the Riemann tensor. We show that such sources do not occur when either of method (a), (b), or (c) are used.

Partial least squares based gene expression analysis in estrogen receptor positive and negative breast tumors.

PubMed

Ma, W; Zhang, T-F; Lu, P; Lu, S H

2014-01-01

Breast cancer is categorized into two broad groups: estrogen receptor positive (ER+) and ER negative (ER-) groups. Previous study proposed that under trastuzumab-based neoadjuvant chemotherapy, tumor initiating cell (TIC) featured ER- tumors response better than ER+ tumors. Exploration of the molecular difference of these two groups may help developing new therapeutic strategies, especially for ER- patients. With gene expression profile from the Gene Expression Omnibus (GEO) database, we performed partial least squares (PLS) based analysis, which is more sensitive than common variance/regression analysis. We acquired 512 differentially expressed genes. Four pathways were found to be enriched with differentially expressed genes, involving immune system, metabolism and genetic information processing process. Network analysis identified five hub genes with degrees higher than 10, including APP, ESR1, SMAD3, HDAC2, and PRKAA1. Our findings provide new understanding for the molecular difference between TIC featured ER- and ER+ breast tumors with the hope offer supports for therapeutic studies.

Partial least squares based identification of Duchenne muscular dystrophy specific genes.

PubMed

An, Hui-bo; Zheng, Hua-cheng; Zhang, Li; Ma, Lin; Liu, Zheng-yan

2013-11-01

Large-scale parallel gene expression analysis has provided a greater ease for investigating the underlying mechanisms of Duchenne muscular dystrophy (DMD). Previous studies typically implemented variance/regression analysis, which would be fundamentally flawed when unaccounted sources of variability in the arrays existed. Here we aim to identify genes that contribute to the pathology of DMD using partial least squares (PLS) based analysis. We carried out PLS-based analysis with two datasets downloaded from the Gene Expression Omnibus (GEO) database to identify genes contributing to the pathology of DMD. Except for the genes related to inflammation, muscle regeneration and extracellular matrix (ECM) modeling, we found some genes with high fold change, which have not been identified by previous studies, such as SRPX, GPNMB, SAT1, and LYZ. In addition, downregulation of the fatty acid metabolism pathway was found, which may be related to the progressive muscle wasting process. Our results provide a better understanding for the downstream mechanisms of DMD.

Maturity associated variance in physical activity and health-related quality of life in adolescent females: a mediated effects model.

PubMed

Smart, Joan E Hunter; Cumming, Sean P; Sherar, Lauren B; Standage, Martyn; Neville, Helen; Malina, Robert M

2012-01-01

This study tested a mediated effects model of psychological and behavioral adaptation to puberty within the context of physical activity (PA). Biological maturity status, physical self-concept, PA, and health-related quality of life (HRQoL) were assessed in 222 female British year 7 to 9 pupils (mean age = 12.7 years, SD = .8). Structural equation modeling using maximum likelihood estimation and bootstrapping procedures supported the hypothesized model. Maturation status was inversely related to perceptions of sport competence, body attractiveness, and physical condition; and indirectly and inversely related to physical self-worth, PA, and HRQoL. Examination of the bootstrap-generated bias-corrected confidence intervals representing the direct and indirect paths between suggested that physical self-concept partially mediated the relations between maturity status and PA, and maturity status and HRQoL. Evidence supports the contention that perceptions of the physical self partially mediate relations maturity, PA, and HRQoL in adolescent females.

Evaluating the interdependence of aging-related changes in visual and auditory acuity, balance, and cognitive functioning.

PubMed

Hofer, Scott M; Berg, Stig; Era, Pertti

2003-06-01

High proportions of shared age-related variance are found among measures of perceptual acuity, balance, muscle strength, and cognitive capabilities in age-heterogeneous, cross-sectional studies. Reliance on cross-sectional studies is problematic, however, because associations may arise from age-related mean trends. Narrow age-cohort samples provide an alternative basis for testing hypotheses regarding associations among rates of change. Cross-domain associations were evaluated in combined 75-year-old cohort samples from Denmark, Finland, and Sweden. In general, no consistent associations were found across sensory, balance, strength, and cognitive domains. These findings indicate that the effects of aging on sensory acuity, balance, and cognitive functioning are likely to be largely independent, multidimensional, and complex at the level of the individual.

Intermittent many-body dynamics at equilibrium

NASA Astrophysics Data System (ADS)

Danieli, C.; Campbell, D. K.; Flach, S.

2017-06-01

The equilibrium value of an observable defines a manifold in the phase space of an ergodic and equipartitioned many-body system. A typical trajectory pierces that manifold infinitely often as time goes to infinity. We use these piercings to measure both the relaxation time of the lowest frequency eigenmode of the Fermi-Pasta-Ulam chain, as well as the fluctuations of the subsequent dynamics in equilibrium. The dynamics in equilibrium is characterized by a power-law distribution of excursion times far off equilibrium, with diverging variance. Long excursions arise from sticky dynamics close to q -breathers localized in normal mode space. Measuring the exponent allows one to predict the transition into nonergodic dynamics. We generalize our method to Klein-Gordon lattices where the sticky dynamics is due to discrete breathers localized in real space.

Fechner's law: where does the log transform come from?

PubMed

Laming, Donald

2010-01-01

This paper looks at Fechner's law in the light of 150 years of subsequent study. In combination with the normal, equal variance, signal-detection model, Fechner's law provides a numerically accurate account of discriminations between two separate stimuli, essentially because the logarithmic transform delivers a model for Weber's law. But it cannot be taken to be a measure of internal sensation because an equally accurate account is provided by a chi(2) model in which stimuli are scaled by their physical magnitude. The logarithmic transform of Fechner's law arises because, for the number of degrees of freedom typically required in the chi(2) model, the logarithm of a chi(2) variable is, to a good approximation, normal. This argument is set within a general theory of sensory discrimination.

A hotspot model for leaf canopies

NASA Technical Reports Server (NTRS)

Jupp, David L. B.; Strahler, Alan H.

1991-01-01

The hotspot effect, which provides important information about canopy structure, is modeled using general principles of environmental physics as driven by parameters of interest in remote sensing, such as leaf size, leaf shape, leaf area index, and leaf angle distribution. Specific examples are derived for canopies of horizontal leaves. The hotspot effect is implemented within the framework of the model developed by Suits (1972) for a canopy of leaves to illustrate what might occur in an agricultural crop. Because the hotspot effect arises from very basic geometrical principles and is scale-free, it occurs similarly in woodlands, forests, crops, rough soil surfaces, and clouds. The scaling principles advanced are also significant factors in the production of image spatial and angular variance and covariance which can be used to assess land cover structure through remote sensing.

Impact of the 2017 Solar Eclipse on Smart Grid

NASA Astrophysics Data System (ADS)

Reda, I.; Andreas, A.; Sengupta, M.; Habte, A.

2017-12-01

With the increasing interest in using solar energy as a major contributor to renewable energy utilization, and with the focus on using smart grids to optimize the use of electrical energy based on demand and resources from different locations, arises the need to know the Moon position in the sky with respect to the Sun. When a solar eclipse occurs, the Moon disk might totally or partially shade the Sun disk, which can affect the irradiance level from the sun disk, consequently, a resource on the grid is affected. The Moon position can then provide the smart grid users with information about potential total or partial solar eclipse at different locations in the grid, so that other resources on the grid can be directed where this might be needed when such phenomena occurs. At least five solar eclipses occur yearly at different locations on earth, they can last three hours or more depending on the location, which can have devastating effects on the smart grid users. On August 21, 2017 a partial solar eclipse will occur at the National Renewable Energy Laboratory in Golden, Colorado, USA. The solar irradiance will be measured during the eclipse and compared to the data generated by a model for validation.

Can misfolded proteins be beneficial? The HAMLET case.

PubMed

Pettersson-Kastberg, Jenny; Aits, Sonja; Gustafsson, Lotta; Mossberg, Anki; Storm, Petter; Trulsson, Maria; Persson, Filip; Mok, K Hun; Svanborg, Catharina

2009-01-01

By changing the three-dimensional structure, a protein can attain new functions, distinct from those of the native protein. Amyloid-forming proteins are one example, in which conformational change may lead to fibril formation and, in many cases, neurodegenerative disease. We have proposed that partial unfolding provides a mechanism to generate new and useful functional variants from a given polypeptide chain. Here we present HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells) as an example where partial unfolding and the incorporation of cofactor create a complex with new, beneficial properties. Native alpha-lactalbumin functions as a substrate specifier in lactose synthesis, but when partially unfolded the protein binds oleic acid and forms the tumoricidal HAMLET complex. When the properties of HAMLET were first described they were surprising, as protein folding intermediates and especially amyloid-forming protein intermediates had been regarded as toxic conformations, but since then structural studies have supported functional diversity arising from a change in fold. The properties of HAMLET suggest a mechanism of structure-function variation, which might help the limited number of human protein genes to generate sufficient structural diversity to meet the diverse functional demands of complex organisms.

Intravenous levetiracetam terminates refractory status epilepticus in two patients with migrating partial seizures in infancy.

PubMed

Cilio, Maria Roberta; Bianchi, Roberto; Balestri, Martina; Onofri, Alfredo; Giovannini, Simona; Di Capua, Matteo; Vigevano, Federico

2009-09-01

To evaluate the efficacy and tolerability of intravenous (IV) levetiracetam in refractory status epilepticus of migrating partial seizures in infancy (MPSI). IV levetiracetam was infused in two infants, first as a loading dose of 60mg/kg in 30min, then at 30mg/kg twice a day. Both infants were continuously monitored with video-EEG before, during and after the drug trial. Blood count, liver enzymes, serum creatinine, ammonia and lactate blood levels were performed repeatedly before and after the IV levetiracetam administration. Follow-up was of 16 and 10 months. EEG monitoring allowed the diagnosis of MPSI, showing the typical seizures pattern in both patients. IV levetiracetam was effective in stopping status epilepticus in both infants. Levetiracetam also prevented the recurrence of status epilepticus during follow-up. No adverse reactions were observed during the infusion phase or during follow-up. MPSI is a newly recognized epileptic syndrome characterized by early onset of intractable partial seizures arisingly independently and sequentially from both hemispheres, migrating from one region of the brain to another and from one hemisphere to another. We report the efficacy of intravenous levetiracetam in resolving refractory status epilepticus in two infants with this new epilepsy syndrome.

Evaluating the response of biological assemblages as potential indicators for restoration measures in an intermittent Mediterranean river.

PubMed

Hughes, Samantha Jane; Santos, Jose; Ferreira, Teresa; Mendes, Ana

2010-08-01

Bioindicators are essential for detecting environmental degradation and for assessing the success of river restoration initiatives. River restoration projects require the identification of environmental and pressure gradients that affect the river system under study and the selection of suitable indicators to assess habitat quality before, during and after restoration. We assessed the response of benthic macroinvertebrates, fish, bird and macrophyte assemblages to environmental and pressure gradients from sites situated upstream and downstream of a cofferdam on the River Odelouca, an intermittent Mediterranean river in southwest Portugal. The Odelouca will be permanently dammed in 2010. Principal Component Analyses (PCA) of environmental and pressure variables revealed that most variance was explained by environmental factors that clearly separated sites upstream and downstream of the partially built cofferdam. The pressure gradient describing physical impacts to the banks and channel as a result of land use change was less distinct. Redundancy Analysis revealed significant levels of explained variance to species distribution patterns in relation to environmental and pressure variables for all 4 biological assemblages. Partial Redundancy analyses revealed high levels of redundancy for pH between groups and that the avifauna was best associated with pressures acting upon the system. Patterns in invertebrates and fish were associated with descriptors of habitat quality, although fish distribution patterns were affected by reduced connectivity. Procrustean and RELATE (Mantel test) analyses gave broadly similar results and supported these findings. We give suggestions on the suitability of key indicator groups such as benthic macroinvertebrates and endemic fish species to assess in stream habitat quality and appropriate restoration measures, such as the release of peak flow patterns that mimic intermittent Mediterranean systems to combat habitat fragmentation and reduced connectivity.

Evaluating the Response of Biological Assemblages as Potential Indicators for Restoration Measures in an Intermittent Mediterranean River

NASA Astrophysics Data System (ADS)

Hughes, Samantha Jane; Santos, Jose; Ferreira, Teresa; Mendes, Ana

2010-08-01

Bioindicators are essential for detecting environmental degradation and for assessing the success of river restoration initiatives. River restoration projects require the identification of environmental and pressure gradients that affect the river system under study and the selection of suitable indicators to assess habitat quality before, during and after restoration. We assessed the response of benthic macroinvertebrates, fish, bird and macrophyte assemblages to environmental and pressure gradients from sites situated upstream and downstream of a cofferdam on the River Odelouca, an intermittent Mediterranean river in southwest Portugal. The Odelouca will be permanently dammed in 2010. Principal Component Analyses (PCA) of environmental and pressure variables revealed that most variance was explained by environmental factors that clearly separated sites upstream and downstream of the partially built cofferdam. The pressure gradient describing physical impacts to the banks and channel as a result of land use change was less distinct. Redundancy Analysis revealed significant levels of explained variance to species distribution patterns in relation to environmental and pressure variables for all 4 biological assemblages. Partial Redundancy analyses revealed high levels of redundancy for pH between groups and that the avifauna was best associated with pressures acting upon the system. Patterns in invertebrates and fish were associated with descriptors of habitat quality, although fish distribution patterns were affected by reduced connectivity. Procrustean and RELATE (Mantel test) analyses gave broadly similar results and supported these findings. We give suggestions on the suitability of key indicator groups such as benthic macroinvertebrates and endemic fish species to assess in stream habitat quality and appropriate restoration measures, such as the release of peak flow patterns that mimic intermittent Mediterranean systems to combat habitat fragmentation and reduced connectivity.

How to consistently link extraversion and intelligence to the catechol-O-methyltransferase (COMT) gene: on defining and measuring psychological phenotypes in neurogenetic research.

PubMed

Wacker, Jan; Mueller, Erik M; Hennig, Jürgen; Stemmler, Gerhard

2012-02-01

The evidence for associations between genetic polymorphisms and complex behavioral/psychological phenotypes (traits) has thus far been weak and inconsistent. Using the well-studied Val158Met polymorphism of the catechol-O-methyltransferase (COMT) gene as an example, we demonstrate that using theoretical models to guide phenotype definition and measuring the phenotypes of interest with a high degree of specificity reveals strong gene-behavior associations that are consistent with prior work and that would have otherwise gone unnoticed. Only after statistically controlling for irrelevant portions of phenotype variance did we observe strong (Cohen's d = 0.33-0.70) and significant associations between COMT Val158Met and both cognitive and affective traits in a healthy male sample (N = 201) in Study 1: Carriers of the Met allele scored higher in fluid intelligence (reasoning) but lower in both crystallized intelligence (general knowledge) and the agency facet of extraversion. In Study 2, we conceptually replicated the association of COMT Val158Met with the agency facet of extraversion after partialing irrelevant phenotype variance in a female sample (N = 565). Finally, through reanalysis of a large published data set we showed that Met allele carriers also scored higher in indicators of fluid intelligence after partialing verbal fluency. Because the Met allele codes for a less efficient variant of the enzyme COMT, resulting in higher levels of extrasynaptic prefrontal dopamine, these observations provide further support for a role for dopamine in both intelligence and extraversion. More importantly, the present findings have important implications for the definition of psychological phenotypes in neurogenetic research.

Comparison of partial least squares and lasso regression techniques as applied to laser-induced breakdown spectroscopy of geological samples

NASA Astrophysics Data System (ADS)

Dyar, M. D.; Carmosino, M. L.; Breves, E. A.; Ozanne, M. V.; Clegg, S. M.; Wiens, R. C.

2012-04-01

A remote laser-induced breakdown spectrometer (LIBS) designed to simulate the ChemCam instrument on the Mars Science Laboratory Rover Curiosity was used to probe 100 geologic samples at a 9-m standoff distance. ChemCam consists of an integrated remote LIBS instrument that will probe samples up to 7 m from the mast of the rover and a remote micro-imager (RMI) that will record context images. The elemental compositions of 100 igneous and highly-metamorphosed rocks are determined with LIBS using three variations of multivariate analysis, with a goal of improving the analytical accuracy. Two forms of partial least squares (PLS) regression are employed with finely-tuned parameters: PLS-1 regresses a single response variable (elemental concentration) against the observation variables (spectra, or intensity at each of 6144 spectrometer channels), while PLS-2 simultaneously regresses multiple response variables (concentrations of the ten major elements in rocks) against the observation predictor variables, taking advantage of natural correlations between elements. Those results are contrasted with those from the multivariate regression technique of the least absolute shrinkage and selection operator (lasso), which is a penalized shrunken regression method that selects the specific channels for each element that explain the most variance in the concentration of that element. To make this comparison, we use results of cross-validation and of held-out testing, and employ unscaled and uncentered spectral intensity data because all of the input variables are already in the same units. Results demonstrate that the lasso, PLS-1, and PLS-2 all yield comparable results in terms of accuracy for this dataset. However, the interpretability of these methods differs greatly in terms of fundamental understanding of LIBS emissions. PLS techniques generate principal components, linear combinations of intensities at any number of spectrometer channels, which explain as much variance in the response variables as possible while avoiding multicollinearity between principal components. When the selected number of principal components is projected back into the original feature space of the spectra, 6144 correlation coefficients are generated, a small fraction of which are mathematically significant to the regression. In contrast, the lasso models require only a small number (< 24) of non-zero correlation coefficients (β values) to determine the concentration of each of the ten major elements. Causality between the positively-correlated emission lines chosen by the lasso and the elemental concentration was examined. In general, the higher the lasso coefficient (β), the greater the likelihood that the selected line results from an emission of that element. Emission lines with negative β values should arise from elements that are anti-correlated with the element being predicted. For elements except Fe, Al, Ti, and P, the lasso-selected wavelength with the highest β value corresponds to the element being predicted, e.g. 559.8 nm for neutral Ca. However, the specific lines chosen by the lasso with positive β values are not always those from the element being predicted. Other wavelengths and the elements that most strongly correlate with them to predict concentration are obviously related to known geochemical correlations or close overlap of emission lines, while others must result from matrix effects. Use of the lasso technique thus directly informs our understanding of the underlying physical processes that give rise to LIBS emissions by determining which lines can best represent concentration, and which lines from other elements are causing matrix effects.

Autogenous Partial Bone Chip Grafting on the Exposed Inferior Alveolar Nerve After Cystic Enucleation.

PubMed

Seo, Mi Hyun; Eo, Mi Young; Cho, Yun Ju; Kim, Soung Min; Lee, Suk Keun

2018-03-01

This prospective study evaluated the clinical effectiveness of the new approach of partial autogenous bone chip grafts for the treatment of mandibular cystic lesions related to the inferior alveolar nerve (IAN). A total of 38 patients treated for mandibular cysts or benign tumors were included in this prospective study and subsequently divided into 3 groups depending on the bone grafting method used: cystic enucleation without a bone graft (group 1), partial bone chip graft covering the exposed IAN (group 2), and autogenous bone graft covering the entire defect (group 3). We evaluated the symptoms, clinical signs, and radiographic changes using dental panorama preoperatively, immediate postoperatively, and at 1, 3, 6, and 12 months postoperatively. Radiographic densities were compared using Adobe Photoshop CS5 (Adobe Systems Inc., San Jose, CA). Repeated measures analysis of variance was used for statistical evaluation with SPSS 22.0 (SPSS Inc, Chicago, IL), and P < 0.05 was considered statistically significant.Radiopacities were the most increased at 1 year postoperative in group 3; groups 2 and 3 did not show statistically significant differences, whereas groups 1 and 3 were statistically significant. In terms of radiographic bone healing with clinical regeneration of the exposed IAN, healing occurred in all patients, although the best healing was achieved in group 2.This autogenous partial bone chip grafting procedure to cover the exposed IAN is suggested as a new surgical protocol for the treatment of cystic lesions associated with the IAN.

Mentalizing in schizophrenia: A multivariate functional MRI study.

PubMed

Martin, Andrew K; Dzafic, Ilvana; Robinson, Gail A; Reutens, David; Mowry, Bryan

2016-12-01

Schizophrenia is associated with mentalizing deficits that impact on social functioning and quality of life. Recently, schizophrenia has been conceptualized as a disorder of neural dysconnectivity and network level analyses offers a means of understanding the underlying deficits leading to mentalizing difficulty. Using an established mentalizing task (The Triangles Task), functional magnetic resonance images (fMRI) were acquired from 19 patients with schizophrenia and 17 age- and sex-matched healthy controls (HCs). Participants were required to watch short animations of two triangles interacting with each other with the interactions either random (no interaction), physical (patterned movement), or mental (intentional movement). Task-based Partial Least Squares (PLS) was used to analyze activation differences and commonalities between the three conditions and the two groups. Seed-based PLS was used to assess functional connectivity with peaks identified in the task-based PLS. Behavioural PLS was then performed using the accuracy from the mental conditions. Patients with schizophrenia performed worse on the mentalizing condition compared to HCs. Task-based PLS revealed one significant latent variable (LV) that explained 42.9% of the variance in the task, with theLV separating the mental condition from the physical and random conditions in patients with schizophrenia, but only the mental from physical in healthy controls. The mental animations were associated with increased modulation of the inferior frontal gyri bilaterally, left superior temporal gyrus, right postcentral gyrus, and left caudate nucleus. The physical/random animations were associated with increased modulation of the right medial frontal gyrus and left superior frontal gyrus. Seed-based PLS identified increased functional connectivity with the left inferior frontal gyrus (liFG) and caudate nucleus in patients with schizophrenia, during the mental and physical interactions, with functional connectivity with the liFG associated with increased performance on the mental animations. The results suggest that mentalizing deficits in schizophrenia may arise due to inefficient social brain networks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nonsymbolic number and cumulative area representations contribute shared and unique variance to symbolic math competence

PubMed Central

Lourenco, Stella F.; Bonny, Justin W.; Fernandez, Edmund P.; Rao, Sonia

2012-01-01

Humans and nonhuman animals share the capacity to estimate, without counting, the number of objects in a set by relying on an approximate number system (ANS). Only humans, however, learn the concepts and operations of symbolic mathematics. Despite vast differences between these two systems of quantification, neural and behavioral findings suggest functional connections. Another line of research suggests that the ANS is part of a larger, more general system of magnitude representation. Reports of cognitive interactions and common neural coding for number and other magnitudes such as spatial extent led us to ask whether, and how, nonnumerical magnitude interfaces with mathematical competence. On two magnitude comparison tasks, college students estimated (without counting or explicit calculation) which of two arrays was greater in number or cumulative area. They also completed a battery of standardized math tests. Individual differences in both number and cumulative area precision (measured by accuracy on the magnitude comparison tasks) correlated with interindividual variability in math competence, particularly advanced arithmetic and geometry, even after accounting for general aspects of intelligence. Moreover, analyses revealed that whereas number precision contributed unique variance to advanced arithmetic, cumulative area precision contributed unique variance to geometry. Taken together, these results provide evidence for shared and unique contributions of nonsymbolic number and cumulative area representations to formally taught mathematics. More broadly, they suggest that uniquely human branches of mathematics interface with an evolutionarily primitive general magnitude system, which includes partially overlapping representations of numerical and nonnumerical magnitude. PMID:23091023

Improved explanation of human intelligence using cortical features with second order moments and regression.

PubMed

Park, Hyunjin; Yang, Jin-ju; Seo, Jongbum; Choi, Yu-yong; Lee, Kun-ho; Lee, Jong-min

2014-04-01

Cortical features derived from magnetic resonance imaging (MRI) provide important information to account for human intelligence. Cortical thickness, surface area, sulcal depth, and mean curvature were considered to explain human intelligence. One region of interest (ROI) of a cortical structure consisting of thousands of vertices contained thousands of measurements, and typically, one mean value (first order moment), was used to represent a chosen ROI, which led to a potentially significant loss of information. We proposed a technological improvement to account for human intelligence in which a second moment (variance) in addition to the mean value was adopted to represent a chosen ROI, so that the loss of information would be less severe. Two computed moments for the chosen ROIs were analyzed with partial least squares regression (PLSR). Cortical features for 78 adults were measured and analyzed in conjunction with the full-scale intelligence quotient (FSIQ). Our results showed that 45% of the variance of the FSIQ could be explained using the combination of four cortical features using two moments per chosen ROI. Our results showed improvement over using a mean value for each ROI, which explained 37% of the variance of FSIQ using the same set of cortical measurements. Our results suggest that using additional second order moments is potentially better than using mean values of chosen ROIs for regression analysis to account for human intelligence. Copyright © 2014 Elsevier Ltd. All rights reserved.

Employee age and tenure within organizations: relationship to workplace satisfaction and workplace climate perceptions.

PubMed

Teclaw, Robert; Osatuke, Katerine; Fishman, Jonathan; Moore, Scott C; Dyrenforth, Sue

2014-01-01

This study estimated the relative influence of age/generation and tenure on job satisfaction and workplace climate perceptions. Data from the 2004, 2008, and 2012 Veterans Health Administration All Employee Survey (sample sizes >100 000) were examined in general linear models, with demographic characteristics simultaneously included as independent variables. Ten dependent variables represented a broad range of employee attitudes. Age/generation and tenure effects were compared through partial η(2) (95% confidence interval), P value of F statistic, and overall model R(2). Demographic variables taken together were only weakly related to employee attitudes, accounting for less than 10% of the variance. Consistently across survey years, for all dependent variables, age and age-squared had very weak to no effects, whereas tenure and tenure-squared had meaningfully greater partial η(2) values. Except for 1 independent variable in 1 year, none of the partial η(2) confidence intervals for age and age-squared overlapped those of tenure and tenure-squared. Much has been made in the popular and professional press of the importance of generational differences in workplace attitudes. Empirical studies have been contradictory and therefore inconclusive. The findings reported here suggest that age/generational differences might not influence employee perceptions to the extent that human resource and management practitioners have been led to believe.

Language structures used by kindergartners with cochlear implants: relationship to phonological awareness, lexical knowledge and hearing loss.

PubMed

Nittrouer, Susan; Sansom, Emily; Low, Keri; Rice, Caitlin; Caldwell-Tarr, Amanda

2014-01-01

Listeners use their knowledge of how language is structured to aid speech recognition in everyday communication. When it comes to children with congenital hearing loss severe enough to warrant cochlear implants (CIs), the question arises of whether these children can acquire the language knowledge needed to aid speech recognition, in spite of only having spectrally degraded signals available to them. That question was addressed in the present study. Specifically, there were three goals: (1) to compare the language structures used by children with CIs to those of children with normal hearing (NH); (2) to assess the amount of variance in the language measures explained by phonological awareness and lexical knowledge; and (3) to assess the amount of variance in the language measures explained by factors related to the hearing loss itself and subsequent treatment. Language samples were obtained and transcribed for 40 children who had just completed kindergarten: 19 with NH and 21 with CIs. Five measures were derived from Systematic Analysis of Language Transcripts: (1) mean length of utterance in morphemes, (2) number of conjunctions, excluding and, (3) number of personal pronouns, (4) number of bound morphemes, and (5) number of different words. Measures were also collected on phonological awareness and lexical knowledge. Statistics examined group differences, as well as the amount of variance in the language measures explained by phonological awareness, lexical knowledge, and factors related to hearing loss and its treatment for children with CIs. Mean scores of children with CIs were roughly one standard deviation below those of children with NH on all language measures, including lexical knowledge, matching outcomes of other studies. Mean scores of children with CIs were closer to two standard deviations below those of children with NH on two out of three measures of phonological awareness (specifically those related to phonemic structure). Lexical knowledge explained significant amounts of variance on three language measures, but only one measure of phonological awareness (sensitivity to word-final phonemic structure) explained any significant amount of unique variance beyond that, and on only one language measure (number of bound morphemes). Age at first implant, but no other factors related to hearing loss or its treatment, explained significant amounts of variance on the language measures, as well. In spite of early intervention and advances in implant technology, children with CIs are still delayed in learning language, but grammatical knowledge is less affected than phonological awareness. Because there was little contribution to language development measured for phonological awareness independent of lexical knowledge, it was concluded that children with CIs could benefit from intervention focused specifically on helping them learn language structures, in spite of the likely phonological deficits they experience as a consequence of having degraded inputs.

Invited Commentary: Agent-Based Models-Bias in the Face of Discovery.

PubMed

Keyes, Katherine M; Tracy, Melissa; Mooney, Stephen J; Shev, Aaron; Cerdá, Magdalena

2017-07-15

Agent-based models (ABMs) have grown in popularity in epidemiologic applications, but the assumptions necessary for valid inference have only partially been articulated. In this issue, Murray et al. (Am J Epidemiol. 2017;186(2):131-142) provided a much-needed analysis of the consequence of some of these assumptions, comparing analysis using an ABM to a similar analysis using the parametric g-formula. In particular, their work focused on the biases that can arise in ABMs that use parameters drawn from distinct populations whose causal structures and baseline outcome risks differ. This demonstration of the quantitative issues that arise in transporting effects between populations has implications not only for ABMs but for all epidemiologic applications, because making use of epidemiologic results requires application beyond a study sample. Broadly, because health arises within complex, dynamic, and hierarchical systems, many research questions cannot be answered statistically without strong assumptions. It will require every tool in our store of methods to properly understand population dynamics if we wish to build an evidence base that is adequate for action. Murray et al.'s results provide insight into these assumptions that epidemiologists can use when selecting a modeling approach. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Conservative, unconditionally stable discretization methods for Hamiltonian equations, applied to wave motion in lattice equations modeling protein molecules

NASA Astrophysics Data System (ADS)

LeMesurier, Brenton

2012-01-01

A new approach is described for generating exactly energy-momentum conserving time discretizations for a wide class of Hamiltonian systems of DEs with quadratic momenta, including mechanical systems with central forces; it is well-suited in particular to the large systems that arise in both spatial discretizations of nonlinear wave equations and lattice equations such as the Davydov System modeling energetic pulse propagation in protein molecules. The method is unconditionally stable, making it well-suited to equations of broadly “Discrete NLS form”, including many arising in nonlinear optics. Key features of the resulting discretizations are exact conservation of both the Hamiltonian and quadratic conserved quantities related to continuous linear symmetries, preservation of time reversal symmetry, unconditional stability, and respecting the linearity of certain terms. The last feature allows a simple, efficient iterative solution of the resulting nonlinear algebraic systems that retain unconditional stability, avoiding the need for full Newton-type solvers. One distinction from earlier work on conservative discretizations is a new and more straightforward nearly canonical procedure for constructing the discretizations, based on a “discrete gradient calculus with product rule” that mimics the essential properties of partial derivatives. This numerical method is then used to study the Davydov system, revealing that previously conjectured continuum limit approximations by NLS do not hold, but that sech-like pulses related to NLS solitons can nevertheless sometimes arise.

Parallel block schemes for large scale least squares computations

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

Golub, G.H.; Plemmons, R.J.; Sameh, A.

1986-04-01

Large scale least squares computations arise in a variety of scientific and engineering problems, including geodetic adjustments and surveys, medical image analysis, molecular structures, partial differential equations and substructuring methods in structural engineering. In each of these problems, matrices often arise which possess a block structure which reflects the local connection nature of the underlying physical problem. For example, such super-large nonlinear least squares computations arise in geodesy. Here the coordinates of positions are calculated by iteratively solving overdetermined systems of nonlinear equations by the Gauss-Newton method. The US National Geodetic Survey will complete this year (1986) the readjustment ofmore » the North American Datum, a problem which involves over 540 thousand unknowns and over 6.5 million observations (equations). The observation matrix for these least squares computations has a block angular form with 161 diagnonal blocks, each containing 3 to 4 thousand unknowns. In this paper parallel schemes are suggested for the orthogonal factorization of matrices in block angular form and for the associated backsubstitution phase of the least squares computations. In addition, a parallel scheme for the calculation of certain elements of the covariance matrix for such problems is described. It is shown that these algorithms are ideally suited for multiprocessors with three levels of parallelism such as the Cedar system at the University of Illinois. 20 refs., 7 figs.« less

New Methods for Estimating Seasonal Potential Climate Predictability

NASA Astrophysics Data System (ADS)

Feng, Xia

This study develops two new statistical approaches to assess the seasonal potential predictability of the observed climate variables. One is the univariate analysis of covariance (ANOCOVA) model, a combination of autoregressive (AR) model and analysis of variance (ANOVA). It has the advantage of taking into account the uncertainty of the estimated parameter due to sampling errors in statistical test, which is often neglected in AR based methods, and accounting for daily autocorrelation that is not considered in traditional ANOVA. In the ANOCOVA model, the seasonal signals arising from external forcing are determined to be identical or not to assess any interannual variability that may exist is potentially predictable. The bootstrap is an attractive alternative method that requires no hypothesis model and is available no matter how mathematically complicated the parameter estimator. This method builds up the empirical distribution of the interannual variance from the resamplings drawn with replacement from the given sample, in which the only predictability in seasonal means arises from the weather noise. These two methods are applied to temperature and water cycle components including precipitation and evaporation, to measure the extent to which the interannual variance of seasonal means exceeds the unpredictable weather noise compared with the previous methods, including Leith-Shukla-Gutzler (LSG), Madden, and Katz. The potential predictability of temperature from ANOCOVA model, bootstrap, LSG and Madden exhibits a pronounced tropical-extratropical contrast with much larger predictability in the tropics dominated by El Nino/Southern Oscillation (ENSO) than in higher latitudes where strong internal variability lowers predictability. Bootstrap tends to display highest predictability of the four methods, ANOCOVA lies in the middle, while LSG and Madden appear to generate lower predictability. Seasonal precipitation from ANOCOVA, bootstrap, and Katz, resembling that for temperature, is more predictable over the tropical regions, and less predictable in extropics. Bootstrap and ANOCOVA are in good agreement with each other, both methods generating larger predictability than Katz. The seasonal predictability of evaporation over land bears considerably similarity with that of temperature using ANOCOVA, bootstrap, LSG and Madden. The remote SST forcing and soil moisture reveal substantial seasonality in their relations with the potentially predictable seasonal signals. For selected regions, either SST or soil moisture or both shows significant relationships with predictable signals, hence providing indirect insight on slowly varying boundary processes involved to enable useful seasonal climate predication. A multivariate analysis of covariance (MANOCOVA) model is established to identify distinctive predictable patterns, which are uncorrelated with each other. Generally speaking, the seasonal predictability from multivariate model is consistent with that from ANOCOVA. Besides unveiling the spatial variability of predictability, MANOCOVA model also reveals the temporal variability of each predictable pattern, which could be linked to the periodic oscillations.

Potential capabilities of Reynolds stress turbulence model in the COMMIX-RSM code

NASA Technical Reports Server (NTRS)

Chang, F. C.; Bottoni, M.

1994-01-01

A Reynolds stress turbulence model has been implemented in the COMMIX code, together with transport equations describing turbulent heat fluxes, variance of temperature fluctuations, and dissipation of turbulence kinetic energy. The model has been verified partially by simulating homogeneous turbulent shear flow, and stable and unstable stratified shear flows with strong buoyancy-suppressing or enhancing turbulence. This article outlines the model, explains the verifications performed thus far, and discusses potential applications of the COMMIX-RSM code in several domains, including, but not limited to, analysis of thermal striping in engineering systems, simulation of turbulence in combustors, and predictions of bubbly and particulate flows.

Individualism, collectivism, and delinquency in Asian American adolescents.

PubMed

Le, Thao N; Stockdale, Gary D

2005-12-01

Although the study of delinquency has previously focused on identifying individual, family, peer, and social risk and protective factors, little empirical research has studied cultural factors and their relations to delinquency. In a large community sample of 329 Chinese, Cambodian, Laotian/Mien, and Vietnamese youths, individualism was positively related to, and collectivism negatively related to, self-reported delinquency, with partial mediation through peer delinquency (PD). Although the percentage of variance in delinquency attributable to individualism-collectivism was small compared to PD, it cannot be discounted as trivial. The results also supported the measurement and structural invariance of these associations across the 4 ethnic groups.

Choice Inconsistencies Among the Elderly: Evidence from Plan Choice in the Medicare Part D Program

PubMed Central

Abaluck, Jason; Gruber, Jonathan

2010-01-01

We evaluate the choices of elders across their insurance options under the Medicare Part D Prescription Drug plan, using a unique data set of prescription drug claims matched to information on the characteristics of choice sets. We document that elders place much more weight on plan premiums than on expected out of pocket costs; value plan financial characteristics beyond any impacts on their own financial expenses or risk; and place almost no value on variance reducing aspects of plans. Partial equilibrium welfare analysis implies that welfare would have been 27% higher if patients had all chosen rationally. PMID:21857716

Electron Heating at Kinetic Scales in Magnetosheath Turbulence

NASA Technical Reports Server (NTRS)

Chasapis, Alexandros; Matthaeus, W. H.; Parashar, T. N.; Lecontel, O.; Retino, A.; Breuillard, H.; Khotyaintsev, Y.; Vaivads, A.; Lavraud, B.; Eriksson, E.;

Measuring Ancient Air Pressure Using Fossilized Cyanobacteria

NASA Astrophysics Data System (ADS)

Silverman, S. N.; Som, S. M.; Gordon, R.; Bebout, B.

2016-12-01

The evolution of Earth's atmosphere has been governed by biological evolution. The dominant air component, nitrogen, has undergone substantial variation over geological time. Today, the partial pressure of nitrogen is 0.79 bar, but this value could have been much higher during early Earth1. The nitrogen partial pressure is postulated to have dropped to a maximum of 0.5 bar before the Great Oxidation Event 2.4 billion years ago, and subsequently recovered to the 0.8 bar value of our modern atmosphere over the next 330 million years2. We are placing constraints on the trajectory of this recovery by investigating how nitrogen partial pressure influences the morphology of a certain species of filamentous cyanobacteria that has been found fossilized in 2 billion year old rocks. These filamentous cyanobacteria convert nitrogen from its dissolved gaseous state (N2) to a biologically useful state (i.e. NH3) when the latter is present at growth-limiting concentrations in their aquatic environment. Such cyanobacteria develop heterocysts (specialized, visually distinct cells), which fix the nitrogen and laterally distribute it to neighboring cells along the one-dimensional filament. We suggest that the distance between heterocysts reflects the nitrogen partial pressure dissolved in water, which is related to atmospheric pN2 by Henry's law. In the laboratory, we are quantifying the relationship between heterocyst distance, variance and covariance to atmospheric pN2 by subjecting cyanobacteria (in media devoid of nitrate) to different partial pressures of N2 at a constant temperature and lighting for the representative species Anabaena variabilis. As far as we know, such experiments have not been previously conducted. This new geobarometer will complement existing methods of quantifying ancient nitrogen partial pressure. 1Goldblatt, Colin, et al. "Nitrogen-enhanced greenhouse warming on early Earth." Nature Geoscience 2 (2009): 891-896. 2Som, S., et al. "Earth's air pressure 2.7 billion years ago constrained to less than half of modern levels." Nature Geoscience 9 (2016): 448-451.

Spectroscopy of SU(4) composite Higgs theory with two distinct fermion representations

NASA Astrophysics Data System (ADS)

Ayyar, Venkitesh; DeGrand, Thomas; Golterman, Maarten; Hackett, Daniel C.; Jay, William I.; Neil, Ethan T.; Shamir, Yigal; Svetitsky, Benjamin

2018-04-01

We have simulated the SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. Such theories arise naturally in the context of composite Higgs models that include a partially composite top quark. We describe the low-lying meson spectrum of the theory and fit the pseudoscalar masses and decay constants to chiral perturbation theory. We infer as well the mass and decay constant of the Goldstone boson corresponding to the nonanomalous U(1) symmetry of the model. Our results are broadly consistent with large-Nc scaling and vector-meson dominance.

Symmetries of Chimera States

NASA Astrophysics Data System (ADS)

Kemeth, Felix P.; Haugland, Sindre W.; Krischer, Katharina

2018-05-01

Symmetry broken states arise naturally in oscillatory networks. In this Letter, we investigate chaotic attractors in an ensemble of four mean-coupled Stuart-Landau oscillators with two oscillators being synchronized. We report that these states with partially broken symmetry, so-called chimera states, have different setwise symmetries in the incoherent oscillators, and in particular, some are and some are not invariant under a permutation symmetry on average. This allows for a classification of different chimera states in small networks. We conclude our report with a discussion of related states in spatially extended systems, which seem to inherit the symmetry properties of their counterparts in small networks.

Squamous cell carcinoma within a horseshoe kidney with associated renal stones detected by computed tomography and magnetic resonance imaging.

PubMed

Imbriaco, Massimo; Iodice, Delfina; Erra, Paola; Terlizzi, Angela; Di Carlo, Rosanna; Di Vito, Concetta; Imbimbo, Ciro

2011-07-01

We describe a 69-year-old man who came to our observation with a history of persistent left flank abdominal pain, fever for several weeks, and a previous history of passing renal stones. Radiological examinations with computed tomography and magnetic resonance imaging revealed a solid mass within the left side of a horseshoe kidney, with associated large renal stones. The patient subsequently underwent partial left nephrectomy. The final diagnosis was consistent with squamous cell carcinoma arising in a horseshoe kidney, with associated renal stones. Copyright © 2011 Elsevier Inc. All rights reserved.

Hybrid of Corannulene and Azacorannulene: Synthesis of a Highly Curved Nitrogen-Containing Buckybowl.

PubMed

Ito, Shingo; Tokimaru, Yuki; Nozaki, Kyoko

2018-06-07

A highly curved nitrogen-containing buckybowl, which can be considered as a corannulene/azacorannulene hybrid, was synthesized and characterized. This molecule has a polycyclic aromatic C40N core, corresponding to a partial azafullerene structure C80-xNx (x = 1,2,3...), and exhibits interesting properties that arise from its large and highly curved pi-surface and the embedded nitrogen atom, which include association with C60, a lower LUMO level relative to azapentabenzocorannulene, and the formation of a radical cationic species upon oxidation. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intermunicipal health care consortia in Brazil: strategic behavior, incentives and sustainability.

PubMed

Teixeira, Luciana; Bugarin, Mauricio; Dourado, Maria Cristina

2006-01-01

This article studies strategic behavior in municipal health care consortia where neighboring municipalities form a partnership to supply high-complexity health care. Each municipality partially funds the organization. Depending on the partnership contract, a free rider problem may jeopardize the organization. A municipality will default its payments if it can still benefit from the services, especially when political pressures for competing expenditure arise. The main result is that the partnership sustainability depends on punishment mechanisms to a defaulting member, the gains from joint provision of services and the overall economic environment. Possible solutions to the incentive problem are discussed.

CPDES3: A preconditioned conjugate gradient solver for linear asymmetric matrix equations arising from coupled partial differential equations in three dimensions

NASA Astrophysics Data System (ADS)

Anderson, D. V.; Koniges, A. E.; Shumaker, D. E.

1988-11-01

Many physical problems require the solution of coupled partial differential equations on three-dimensional domains. When the time scales of interest dictate an implicit discretization of the equations a rather complicated global matrix system needs solution. The exact form of the matrix depends on the choice of spatial grids and on the finite element or finite difference approximations employed. CPDES3 allows each spatial operator to have 7, 15, 19, or 27 point stencils and allows for general couplings between all of the component PDE's and it automatically generates the matrix structures needed to perform the algorithm. The resulting sparse matrix equation is solved by either the preconditioned conjugate gradient (CG) method or by the preconditioned biconjugate gradient (BCG) algorithm. An arbitrary number of component equations are permitted only limited by available memory. In the sub-band representation used, we generate an algorithm that is written compactly in terms of indirect induces which is vectorizable on some of the newer scientific computers.

CPDES2: A preconditioned conjugate gradient solver for linear asymmetric matrix equations arising from coupled partial differential equations in two dimensions

NASA Astrophysics Data System (ADS)

Anderson, D. V.; Koniges, A. E.; Shumaker, D. E.

1988-11-01

Many physical problems require the solution of coupled partial differential equations on two-dimensional domains. When the time scales of interest dictate an implicit discretization of the equations a rather complicated global matrix system needs solution. The exact form of the matrix depends on the choice of spatial grids and on the finite element or finite difference approximations employed. CPDES2 allows each spatial operator to have 5 or 9 point stencils and allows for general couplings between all of the component PDE's and it automatically generates the matrix structures needed to perform the algorithm. The resulting sparse matrix equation is solved by either the preconditioned conjugate gradient (CG) method or by the preconditioned biconjugate gradient (BCG) algorithm. An arbitrary number of component equations are permitted only limited by available memory. In the sub-band representation used, we generate an algorithm that is written compactly in terms of indirect indices which is vectorizable on some of the newer scientific computers.

Reduction by symmetries in singular quantum-mechanical problems: General scheme and application to Aharonov-Bohm model

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

Smirnov, A. G., E-mail: smirnov@lpi.ru

2015-12-15

We develop a general technique for finding self-adjoint extensions of a symmetric operator that respects a given set of its symmetries. Problems of this type naturally arise when considering two- and three-dimensional Schrödinger operators with singular potentials. The approach is based on constructing a unitary transformation diagonalizing the symmetries and reducing the initial operator to the direct integral of a suitable family of partial operators. We prove that symmetry preserving self-adjoint extensions of the initial operator are in a one-to-one correspondence with measurable families of self-adjoint extensions of partial operators obtained by reduction. The general scheme is applied to themore » three-dimensional Aharonov-Bohm Hamiltonian describing the electron in the magnetic field of an infinitely thin solenoid. We construct all self-adjoint extensions of this Hamiltonian, invariant under translations along the solenoid and rotations around it, and explicitly find their eigenfunction expansions.« less

Pedigree-based estimation of covariance between dominance deviations and additive genetic effects in closed rabbit lines considering inbreeding and using a computationally simpler equivalent model.

PubMed

Fernández, E N; Legarra, A; Martínez, R; Sánchez, J P; Baselga, M

2017-06-01

Inbreeding generates covariances between additive and dominance effects (breeding values and dominance deviations). In this work, we developed and applied models for estimation of dominance and additive genetic variances and their covariance, a model that we call "full dominance," from pedigree and phenotypic data. Estimates with this model such as presented here are very scarce both in livestock and in wild genetics. First, we estimated pedigree-based condensed probabilities of identity using recursion. Second, we developed an equivalent linear model in which variance components can be estimated using closed-form algorithms such as REML or Gibbs sampling and existing software. Third, we present a new method to refer the estimated variance components to meaningful parameters in a particular population, i.e., final partially inbred generations as opposed to outbred base populations. We applied these developments to three closed rabbit lines (A, V and H) selected for number of weaned at the Polytechnic University of Valencia. Pedigree and phenotypes are complete and span 43, 39 and 14 generations, respectively. Estimates of broad-sense heritability are 0.07, 0.07 and 0.05 at the base versus 0.07, 0.07 and 0.09 in the final generations. Narrow-sense heritability estimates are 0.06, 0.06 and 0.02 at the base versus 0.04, 0.04 and 0.01 at the final generations. There is also a reduction in the genotypic variance due to the negative additive-dominance correlation. Thus, the contribution of dominance variation is fairly large and increases with inbreeding and (over)compensates for the loss in additive variation. In addition, estimates of the additive-dominance correlation are -0.37, -0.31 and 0.00, in agreement with the few published estimates and theoretical considerations. © 2017 Blackwell Verlag GmbH.

A new process sensitivity index to identify important system processes under process model and parametric uncertainty

DOE PAGES

Dai, Heng; Ye, Ming; Walker, Anthony P.; ...

2017-03-28

A hydrological model consists of multiple process level submodels, and each submodel represents a process key to the operation of the simulated system. Global sensitivity analysis methods have been widely used to identify important processes for system model development and improvement. The existing methods of global sensitivity analysis only consider parametric uncertainty, and are not capable of handling model uncertainty caused by multiple process models that arise from competing hypotheses about one or more processes. To address this problem, this study develops a new method to probe model output sensitivity to competing process models by integrating model averaging methods withmore » variance-based global sensitivity analysis. A process sensitivity index is derived as a single summary measure of relative process importance, and the index includes variance in model outputs caused by uncertainty in both process models and their parameters. Here, for demonstration, the new index is used to assign importance to the processes of recharge and geology in a synthetic study of groundwater reactive transport modeling. The recharge process is simulated by two models that convert precipitation to recharge, and the geology process is simulated by two models of hydraulic conductivity. Each process model has its own random parameters. Finally, the new process sensitivity index is mathematically general, and can be applied to a wide range of problems in hydrology and beyond.« less

Sequential causal inference: Application to randomized trials of adaptive treatment strategies

PubMed Central

Dawson, Ree; Lavori, Philip W.

2009-01-01

SUMMARY Clinical trials that randomize subjects to decision algorithms, which adapt treatments over time according to individual response, have gained considerable interest as investigators seek designs that directly inform clinical decision making. We consider designs in which subjects are randomized sequentially at decision points, among adaptive treatment options under evaluation. We present a sequential method to estimate the comparative effects of the randomized adaptive treatments, which are formalized as adaptive treatment strategies. Our causal estimators are derived using Bayesian predictive inference. We use analytical and empirical calculations to compare the predictive estimators to (i) the ‘standard’ approach that allocates the sequentially obtained data to separate strategy-specific groups as would arise from randomizing subjects at baseline; (ii) the semi-parametric approach of marginal mean models that, under appropriate experimental conditions, provides the same sequential estimator of causal differences as the proposed approach. Simulation studies demonstrate that sequential causal inference offers substantial efficiency gains over the standard approach to comparing treatments, because the predictive estimators can take advantage of the monotone structure of shared data among adaptive strategies. We further demonstrate that the semi-parametric asymptotic variances, which are marginal ‘one-step’ estimators, may exhibit significant bias, in contrast to the predictive variances. We show that the conditions under which the sequential method is attractive relative to the other two approaches are those most likely to occur in real studies. PMID:17914714

Floral trait variation and integration as a function of sexual deception in Gorteria diffusa

PubMed Central

Ellis, Allan G.; Brockington, Samuel F.; de Jager, Marinus L.; Mellers, Gregory; Walker, Rachel H.; Glover, Beverley J.

2014-01-01

Phenotypic integration, the coordinated covariance of suites of morphological traits, is critical for proper functioning of organisms. Angiosperm flowers are complex structures comprising suites of traits that function together to achieve effective pollen transfer. Floral integration could reflect shared genetic and developmental control of these traits, or could arise through pollinator-imposed stabilizing correlational selection on traits. We sought to expose mechanisms underlying floral trait integration in the sexually deceptive daisy, Gorteria diffusa, by testing the hypothesis that stabilizing selection imposed by male pollinators on floral traits involved in mimicry has resulted in tighter integration. To do this, we quantified patterns of floral trait variance and covariance in morphologically divergent G. diffusa floral forms representing a continuum in the levels of sexual deception. We show that integration of traits functioning in visual attraction of male pollinators increases with pollinator deception, and is stronger than integration of non-mimicry trait modules. Consistent patterns of within-population trait variance and covariance across floral forms suggest that integration has not been built by stabilizing correlational selection on genetically independent traits. Instead pollinator specialization has selected for tightened integration within modules of linked traits. Despite potentially strong constraint on morphological evolution imposed by developmental genetic linkages between traits, we demonstrate substantial divergence in traits across G. diffusa floral forms and show that divergence has often occurred without altering within-population patterns of trait correlations. PMID:25002705

To kill a kangaroo: understanding the decision to pursue high-risk/high-gain resources.

PubMed

Jones, James Holland; Bird, Rebecca Bliege; Bird, Douglas W

2013-09-22

In this paper, we attempt to understand hunter-gatherer foraging decisions about prey that vary in both the mean and variance of energy return using an expected utility framework. We show that for skewed distributions of energetic returns, the standard linear variance discounting (LVD) model for risk-sensitive foraging can produce quite misleading results. In addition to creating difficulties for the LVD model, the skewed distributions characteristic of hunting returns create challenges for estimating probability distribution functions required for expected utility. We present a solution using a two-component finite mixture model for foraging returns. We then use detailed foraging returns data based on focal follows of individual hunters in Western Australia hunting for high-risk/high-gain (hill kangaroo) and relatively low-risk/low-gain (sand monitor) prey. Using probability densities for the two resources estimated from the mixture models, combined with theoretically sensible utility curves characterized by diminishing marginal utility for the highest returns, we find that the expected utility of the sand monitors greatly exceeds that of kangaroos despite the fact that the mean energy return for kangaroos is nearly twice as large as that for sand monitors. We conclude that the decision to hunt hill kangaroos does not arise simply as part of an energetic utility-maximization strategy and that additional social, political or symbolic benefits must accrue to hunters of this highly variable prey.

A new process sensitivity index to identify important system processes under process model and parametric uncertainty

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

Dai, Heng; Ye, Ming; Walker, Anthony P.

Hydrological models are always composed of multiple components that represent processes key to intended model applications. When a process can be simulated by multiple conceptual-mathematical models (process models), model uncertainty in representing the process arises. While global sensitivity analysis methods have been widely used for identifying important processes in hydrologic modeling, the existing methods consider only parametric uncertainty but ignore the model uncertainty for process representation. To address this problem, this study develops a new method to probe multimodel process sensitivity by integrating the model averaging methods into the framework of variance-based global sensitivity analysis, given that the model averagingmore » methods quantify both parametric and model uncertainty. A new process sensitivity index is derived as a metric of relative process importance, and the index includes variance in model outputs caused by uncertainty in both process models and model parameters. For demonstration, the new index is used to evaluate the processes of recharge and geology in a synthetic study of groundwater reactive transport modeling. The recharge process is simulated by two models that converting precipitation to recharge, and the geology process is also simulated by two models of different parameterizations of hydraulic conductivity; each process model has its own random parameters. The new process sensitivity index is mathematically general, and can be applied to a wide range of problems in hydrology and beyond.« less

A new process sensitivity index to identify important system processes under process model and parametric uncertainty

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

Dai, Heng; Ye, Ming; Walker, Anthony P.

A hydrological model consists of multiple process level submodels, and each submodel represents a process key to the operation of the simulated system. Global sensitivity analysis methods have been widely used to identify important processes for system model development and improvement. The existing methods of global sensitivity analysis only consider parametric uncertainty, and are not capable of handling model uncertainty caused by multiple process models that arise from competing hypotheses about one or more processes. To address this problem, this study develops a new method to probe model output sensitivity to competing process models by integrating model averaging methods withmore » variance-based global sensitivity analysis. A process sensitivity index is derived as a single summary measure of relative process importance, and the index includes variance in model outputs caused by uncertainty in both process models and their parameters. Here, for demonstration, the new index is used to assign importance to the processes of recharge and geology in a synthetic study of groundwater reactive transport modeling. The recharge process is simulated by two models that convert precipitation to recharge, and the geology process is simulated by two models of hydraulic conductivity. Each process model has its own random parameters. Finally, the new process sensitivity index is mathematically general, and can be applied to a wide range of problems in hydrology and beyond.« less

Back to Pupillometry: How Cortical Network State Fluctuations Tracked by Pupil Dynamics Could Explain Neural Signal Variability in Human Cognitive Neuroscience

PubMed Central

2017-01-01

Abstract The mammalian thalamocortical system generates intrinsic activity reflecting different states of excitability, arising from changes in the membrane potentials of underlying neuronal networks. Fluctuations between these states occur spontaneously, regularly, and frequently throughout awake periods and influence stimulus encoding, information processing, and neuronal and behavioral responses. Changes of pupil size have recently been identified as a reliable marker of underlying neuronal membrane potential and thus can encode associated network state changes in rodent cortex. This suggests that pupillometry, a ubiquitous measure of pupil dilation in cognitive neuroscience, could be used as an index for network state fluctuations also for human brain signals. Considering this variable may explain task-independent variance in neuronal and behavioral signals that were previously disregarded as noise. PMID:29379876

Sexual selection expedites the evolution of pesticide resistance.

PubMed

Jacomb, Frances; Marsh, Jason; Holman, Luke

2016-12-01

The evolution of insecticide resistance by crop pests and disease vectors causes serious problems for agriculture and health. Sexual selection can accelerate or hinder adaptation to abiotic challenges in a variety of ways, but the effect of sexual selection on resistance evolution is little studied. Here, we examine this question using experimental evolution in the pest insect Tribolium castaneum. The experimental removal of sexual selection slowed the evolution of resistance in populations treated with pyrethroid pesticide, and also reduced the rate at which resistance was lost from pesticide-free populations. These results suggest that selection arising from variance in mating and fertilization success can augment natural selection on pesticide resistance, meaning that sexual selection should be considered when designing strategies to limit the evolution of pesticide resistance. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

Epidemic thresholds for bipartite networks

NASA Astrophysics Data System (ADS)

Hernández, D. G.; Risau-Gusman, S.

2013-11-01

It is well known that sexually transmitted diseases (STD) spread across a network of human sexual contacts. This network is most often bipartite, as most STD are transmitted between men and women. Even though network models in epidemiology have quite a long history now, there are few general results about bipartite networks. One of them is the simple dependence, predicted using the mean field approximation, between the epidemic threshold and the average and variance of the degree distribution of the network. Here we show that going beyond this approximation can lead to qualitatively different results that are supported by numerical simulations. One of the new features, that can be relevant for applications, is the existence of a critical value for the infectivity of each population, below which no epidemics can arise, regardless of the value of the infectivity of the other population.

A Computational Approach for Probabilistic Analysis of Water Impact Simulations

NASA Technical Reports Server (NTRS)

Horta, Lucas G.; Mason, Brian H.; Lyle, Karen H.

2009-01-01

NASA's development of new concepts for the Crew Exploration Vehicle Orion presents many similar challenges to those worked in the sixties during the Apollo program. However, with improved modeling capabilities, new challenges arise. For example, the use of the commercial code LS-DYNA, although widely used and accepted in the technical community, often involves high-dimensional, time consuming, and computationally intensive simulations. The challenge is to capture what is learned from a limited number of LS-DYNA simulations to develop models that allow users to conduct interpolation of solutions at a fraction of the computational time. This paper presents a description of the LS-DYNA model, a brief summary of the response surface techniques, the analysis of variance approach used in the sensitivity studies, equations used to estimate impact parameters, results showing conditions that might cause injuries, and concluding remarks.

Zernike expansion of derivatives and Laplacians of the Zernike circle polynomials.

PubMed

Janssen, A J E M

2014-07-01

The partial derivatives and Laplacians of the Zernike circle polynomials occur in various places in the literature on computational optics. In a number of cases, the expansion of these derivatives and Laplacians in the circle polynomials are required. For the first-order partial derivatives, analytic results are scattered in the literature. Results start as early as 1942 in Nijboer's thesis and continue until present day, with some emphasis on recursive computation schemes. A brief historic account of these results is given in the present paper. By choosing the unnormalized version of the circle polynomials, with exponential rather than trigonometric azimuthal dependence, and by a proper combination of the two partial derivatives, a concise form of the expressions emerges. This form is appropriate for the formulation and solution of a model wavefront sensing problem of reconstructing a wavefront on the level of its expansion coefficients from (measurements of the expansion coefficients of) the partial derivatives. It turns out that the least-squares estimation problem arising here decouples per azimuthal order m, and per m the generalized inverse solution assumes a concise analytic form so that singular value decompositions are avoided. The preferred version of the circle polynomials, with proper combination of the partial derivatives, also leads to a concise analytic result for the Zernike expansion of the Laplacian of the circle polynomials. From these expansions, the properties of the Laplacian as a mapping from the space of circle polynomials of maximal degree N, as required in the study of the Neumann problem associated with the transport-of-intensity equation, can be read off within a single glance. Furthermore, the inverse of the Laplacian on this space is shown to have a concise analytic form.

Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.

PubMed

Verberk, Wilco C E P; Bilton, David T; Calosi, Piero; Spicer, John I

2011-08-01

Aquatic ectotherms face the continuous challenge of capturing sufficient oxygen from their environment as the diffusion rate of oxygen in water is 3 x 10(5) times lower than in air. Despite the recognized importance of oxygen in shaping aquatic communities, consensus on what drives environmental oxygen availability is lacking. Physiologists emphasize oxygen partial pressure, while ecologists emphasize oxygen solubility, traditionally expressing oxygen in terms of concentrations. To resolve the question of whether partial pressure or solubility limits oxygen supply in nature, we return to first principles and derive an index of oxygen supply from Fick's classic first law of diffusion. This oxygen supply index (OSI) incorporates both partial pressure and solubility. Our OSI successfully explains published patterns in body size and species across environmental clines linked to differences in oxygen partial pressure (altitude, organic pollution) or oxygen solubility (temperature and salinity). Moreover, the OSI was more accurately and consistently related to these ecological patterns than other measures of oxygen (oxygen saturation, dissolved oxygen concentration, biochemical oxygen demand concentrations) and similarly outperformed temperature and altitude, which covaried with these environmental clines. Intriguingly, by incorporating gas diffusion rates, it becomes clear that actually more oxygen is available to an organism in warmer habitats where lower oxygen concentrations would suggest the reverse. Under our model, the observed reductions in aerobic performance in warmer habitats do not arise from lower oxygen concentrations, but instead through organismal oxygen demand exceeding supply. This reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to ongoing global climate shifts.

Tissue-engineering with muscle fiber fragments improves the strength of a weak abdominal wall in rats.

PubMed

Jangö, Hanna; Gräs, Søren; Christensen, Lise; Lose, Gunnar

2017-02-01

Alternative approaches to reinforce the native tissue in patients with pelvic organ prolapse (POP) are needed to improve surgical outcome. Our aims were to develop a weakened abdominal wall in a rat model to mimic the weakened vaginal wall in women with POP and then evaluate the regenerative potential of a quickly biodegradable synthetic scaffold, methoxypolyethylene glycol polylactic-co-glycolic acid (MPEG-PLGA), seeded with autologous muscle fiber fragments (MFFs) using this model. In an initial pilot study with 15 animals, significant weakening of the abdominal wall and a feasible technique was established by creating a partial defect with removal of one abdominal muscle layer. Subsequently, 18 rats were evenly divided into three groups: (1) unrepaired partial defect; (2) partial defect repaired with MPEG-PLGA; (3) partial defect repaired with MPEG-PLGA and MFFs labeled with PKH26-fluorescence dye. After 8 weeks, we performed histopathological and immunohistochemical testing, fluorescence analysis, and uniaxial biomechanical testing. Both macroscopically and microscopically, the MPEG-PLGA scaffold was fully degraded, with no signs of an inflammatory or foreign-body response. PKH26-positive cells were found in all animals from the group with added MFFs. Analysis of variance (ANOVA) showed a significant difference between groups with respect to load at failure (p = 0.028), and post hoc testing revealed that the group with MPEG-PLGA and MFFs showed a significantly higher strength than the group with MPEG-PLGA alone (p = 0.034). Tissue-engineering with MFFs seeded on a scaffold of biodegradable MPEG-PLGA might be an interesting adjunct to future POP repair.

Detrended Partial-Cross-Correlation Analysis: A New Method for Analyzing Correlations in Complex System

PubMed Central

Yuan, Naiming; Fu, Zuntao; Zhang, Huan; Piao, Lin; Xoplaki, Elena; Luterbacher, Juerg

2015-01-01

In this paper, a new method, detrended partial-cross-correlation analysis (DPCCA), is proposed. Based on detrended cross-correlation analysis (DCCA), this method is improved by including partial-correlation technique, which can be applied to quantify the relations of two non-stationary signals (with influences of other signals removed) on different time scales. We illustrate the advantages of this method by performing two numerical tests. Test I shows the advantages of DPCCA in handling non-stationary signals, while Test II reveals the “intrinsic” relations between two considered time series with potential influences of other unconsidered signals removed. To further show the utility of DPCCA in natural complex systems, we provide new evidence on the winter-time Pacific Decadal Oscillation (PDO) and the winter-time Nino3 Sea Surface Temperature Anomaly (Nino3-SSTA) affecting the Summer Rainfall over the middle-lower reaches of the Yangtze River (SRYR). By applying DPCCA, better significant correlations between SRYR and Nino3-SSTA on time scales of 6 ~ 8 years are found over the period 1951 ~ 2012, while significant correlations between SRYR and PDO on time scales of 35 years arise. With these physically explainable results, we have confidence that DPCCA is an useful method in addressing complex systems. PMID:25634341

Account of an optical beam spreading caused by turbulence for the problem of partially coherent wavefield propagation through inhomogeneous absorbing media

NASA Astrophysics Data System (ADS)

Dudorov, Vadim V.; Kolosov, Valerii V.

2003-04-01

The propagation problem for partially coherent wave fields in inhomogeneous media is considered in this work. The influence of refraction, inhomogeneity of gain medium properties and refraction parameter fluctuations on target characteristics of radiation are taken into consideration. Such problems arise in the study of laser propagation on atmosphere paths, under investigation of directional radiation pattern forming for lasers which gain media is characterized by strong fluctuation of dielectric constant and for lasers which resonator have an atmosphere area. The ray-tracing technique allows us to make effective algorithms for modeling of a partially coherent wave field propagation through inhomogeneous random media is presented for case when the influecne of an optical wave refraction, the influence of the inhomogeiety of radiaitn amplification or absorption, and also the influence of fluctuations of a refraction parameter on target radiation parameters are basic. Novelty of the technique consists in the account of the additional refraction caused by inhomogeneity of gain, and also in the method of an account of turbulent distortions of a beam with any initial coherence allowing to execute construction of effective numerical algorithms. The technique based on the solution of the equation for coherence function of the second order.

Impact of the 2017 Solar Eclipse on the Smart Grid

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

Habte, Aron M; Reda, Ibrahim M; Andreas, Afshin M

With the increasing interest in using solar energy as a major contributor to the use of renewable generation, and with the focus on using smart grids to optimize the use of electrical energy based on demand and resources from different locations, the need arises to know the moons position in the sky with respect to the sun. When a solar eclipse occurs, the moon disk might totally or partially shade the sun disk, which can affect the irradiance level from the sun disk, consequently affecting a resource on the electric grid. The moons position can then provide smart grid usersmore » with information about how potential total or partial solar eclipses might affect different locations on the grid so that other resources on the grid can be directed to where they might be needed when such phenomena occurs. At least five solar eclipses occur yearly at different locations on Earth, they can last 3 hours or more depending on the location, and they can affect smart grid users. On August 21, 2017, a partial and full solar eclipse occurred in many locations in the United States, including at the National Renewable Energy Laboratory in Golden, Colorado. Solar irradiance measurements during the eclipse were compared to the data generated by a model for validation at eight locations.« less

Simple graph models of information spread in finite populations

PubMed Central

Voorhees, Burton; Ryder, Bergerud

2015-01-01

We consider several classes of simple graphs as potential models for information diffusion in a structured population. These include biases cycles, dual circular flows, partial bipartite graphs and what we call ‘single-link’ graphs. In addition to fixation probabilities, we study structure parameters for these graphs, including eigenvalues of the Laplacian, conductances, communicability and expected hitting times. In several cases, values of these parameters are related, most strongly so for partial bipartite graphs. A measure of directional bias in cycles and circular flows arises from the non-zero eigenvalues of the antisymmetric part of the Laplacian and another measure is found for cycles as the value of the transition probability for which hitting times going in either direction of the cycle are equal. A generalization of circular flow graphs is used to illustrate the possibility of tuning edge weights to match pre-specified values for graph parameters; in particular, we show that generalizations of circular flows can be tuned to have fixation probabilities equal to the Moran probability for a complete graph by tuning vertex temperature profiles. Finally, single-link graphs are introduced as an example of a graph involving a bottleneck in the connection between two components and these are compared to the partial bipartite graphs. PMID:26064661

Model-based analysis of multi-shell diffusion MR data for tractography: How to get over fitting problems

PubMed Central

Jbabdi, Saad; Sotiropoulos, Stamatios N; Savio, Alexander M; Graña, Manuel; Behrens, Timothy EJ

2012-01-01

In this article, we highlight an issue that arises when using multiple b-values in a model-based analysis of diffusion MR data for tractography. The non-mono-exponential decay, commonly observed in experimental data, is shown to induce over-fitting in the distribution of fibre orientations when not considered in the model. Extra fibre orientations perpendicular to the main orientation arise to compensate for the slower apparent signal decay at higher b-values. We propose a simple extension to the ball and stick model based on a continuous Gamma distribution of diffusivities, which significantly improves the fitting and reduces the over-fitting. Using in-vivo experimental data, we show that this model outperforms a simpler, noise floor model, especially at the interfaces between brain tissues, suggesting that partial volume effects are a major cause of the observed non-mono-exponential decay. This model may be helpful for future data acquisition strategies that may attempt to combine multiple shells to improve estimates of fibre orientations in white matter and near the cortex. PMID:22334356

POLARIZED SCATTERING OF LIGHT FOR ARBITRARY MAGNETIC FIELDS WITH LEVEL-CROSSINGS FROM THE COMBINATION OF HYPERFINE AND FINE STRUCTURE SPLITTINGS

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

Sowmya, K.; Nagendra, K. N.; Sampoorna, M.

2015-12-01

Interference between magnetic substates of the hyperfine structure states belonging to different fine structure states of the same term influences the polarization for some of the diagnostically important lines of the Sun's spectrum, like the sodium and lithium doublets. The polarization signatures of this combined interference contain information on the properties of the solar magnetic fields. Motivated by this, in the present paper, we study the problem of polarized scattering on a two-term atom with hyperfine structure by accounting for the partial redistribution in the photon frequencies arising due to the Doppler motions of the atoms. We consider the scatteringmore » atoms to be under the influence of a magnetic field of arbitrary strength and develop a formalism based on the Kramers–Heisenberg approach to calculate the scattering cross section for this process. We explore the rich polarization effects that arise from various level-crossings in the Paschen–Back regime in a single scattering case using the lithium atomic system as a concrete example that is relevant to the Sun.« less

Identification of small peptides arising from hydrolysis of meat proteins in dry fermented sausages.

PubMed

López, Constanza M; Bru, Elena; Vignolo, Graciela M; Fadda, Silvina G

2015-06-01

In this study, proteolysis and low molecular weight (LMW) peptides (<3kDa) from commercial Argentinean fermented sausages were characterized by applying a peptidomic approach. Protein profiles and peptides obtained by Tricine-SDS-PAGE and RP-HPLC-MS, respectively, allowed distinguishing two different types of fermented sausages, although no specific biomarkers relating to commercial brands or quality were recognized. From electrophoresis, α-actin, myoglobin, creatine kinase M-type and L-lactate dehydrogenase were degraded at different intensities. In addition, a partial characterization of fermented sausage peptidome through the identification of 36 peptides, in the range of 1000-2100 Da, arising from sarcoplasmic (28) and myofibrillar (8) proteins was achieved. These peptides had been originated from α-actin, myoglobin, and creatine kinase M-type, but also from the hydrolysis of other proteins not previously reported. Although muscle enzymes exerted a major role on peptidogenesis, microbial contribution cannot be excluded as it was postulated herein. This work represents a first peptidomic approach for fermented sausages, thereby providing a baseline to define key peptides acting as potential biomarkers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Surgical animal models of neuropathic pain: Pros and Cons.

PubMed

Challa, Siva Reddy

2015-03-01

One of the biggest challenges for discovering more efficacious drugs for the control of neuropathic pain has been the diversity of chronic pain states in humans. It is now acceptable that different mechanisms contribute to normal physiologic pain, pain arising from tissue damage and pain arising from injury to the nervous system. To study pain transmission, spot novel pain targets and characterize the potential analgesic profile of new chemical entities, numerous experimental animal pain models have been developed that attempt to simulate the many human pain conditions. Among the neuropathic pain models, surgical models have paramount importance in the induction of pain states. Many surgical animal models exist, like the chronic constriction injury (CCI) to the sciatic nerve, partial sciatic nerve ligation (pSNL), spinal nerve ligation (SNL), spared nerve injury (SNI), brachial plexus avulsion (BPA), sciatic nerve transaction (SNT) and sciatic nerve trisection. Most of these models induce responses similar to those found in causalgia, a syndrome of sustained burning pain often seen in the distal extremity after partial peripheral nerve injury in humans. Researchers most commonly use these surgical models in both rats and mice during drug discovery to screen new chemical entities for efficacy in the area of neuropathic pain. However, there is scant literature that provides a comparative discussion of all these surgical models. Each surgical model has its own benefits and limitations. It is very difficult for a researcher to choose a suitable surgical animal model to suit their experimental set-up. Therefore, particular attention has been given in this review to comparatively provide the pros and cons of each model of surgically induced neuropathic pain.

FINANCIAL CAPACITY OF OLDER AFRICAN AMERICANS WITH AMNESTIC MILD COGNITIVE IMPAIRMENT

PubMed Central

Triebel, Kristen L.; Okonkwo, Ozioma C.; Martin, Roy; Griffith, H. Randall; Crowther, Martha; Marson, Daniel C.

2010-01-01

This study investigated financial abilities of 154 patients with mild cognitive impairment (MCI) (116 Caucasian, 38 African American) using the Financial Capacity Instrument (FCI). In a series of linear regression models, we examined the effect of race on FCI performance and identified preliminary predictor variables that mediated observed racial differences on the FCI. Prior/premorbid abilities were identified. Predictor variables examined in the models included race and other demographic factors (age, education, gender), performance on global cognitive measures (MMSE, DRS-2 Total Score), history of cardiovascular disease (hypertension, diabetes, hypercholesterolemia), and a measure of educational achievement (WRAT-3 Arithmetic). African American patients with MCI performed below Caucasian patients with MCI on six of the seven FCI domains examined and on the FCI total score. WRAT-3 Arithmetic emerged as a partial mediator of group differences on the FCI, accounting for 54% of variance. In contrast, performance on global cognitive measures and history of cardiovascular disease only accounted for 14% and 2%, respectively, of the variance. Racial disparities in financial capacity appear to exist among patients with amnestic MCI. Basic academic math skills related to educational opportunity and quality of education account for a substantial proportion of the group difference in financial performance. PMID:20625268

Chaos, Poverty, and Parenting: Predictors of Early Language Development

PubMed Central

Vernon-Feagans, Lynne; Garrett-Peters, Patricia; Willoughby, Mike; Mills-Koonce, Roger

2011-01-01

Studies have shown that distal family risk factors like poverty and maternal education are strongly related to children's early language development. Yet, few studies have examined these risk factors in combination with more proximal day-to-day experiences of children that might be critical to understanding variation in early language. Young children's exposure to a chronically chaotic household may be one critical experience that is related to poorer language, beyond the contribution of SES and other demographic variables. In addition, it is not clear whether parenting might mediate the relationship between chaos and language. The purpose of this study was to understand how multiple indicators of chaos over children's first three years of life, in a representative sample of children living in low wealth rural communities, were related to child expressive and receptive language at 36 months. Factor analysis of 10 chaos indicators over five time periods suggested two factors that were named household disorganization and instability. Results suggested that after accounting for thirteen covariates like maternal education and poverty, one of two chaos composites (household disorganization) accounted for significant variance in receptive and expressive language. Parenting partially mediated this relationship although household disorganization continued to account for unique variance in predicting early language. PMID:23049162

Financial capacity of older African Americans with amnestic mild cognitive impairment.

PubMed

Triebel, Kristen L; Okonkwo, Ozioma C; Martin, Roy; Griffith, Henry Randall; Crowther, Martha; Marson, Daniel C

2010-01-01

This study investigated financial abilities of 154 patients with mild cognitive impairment (MCI) (116 white, 38 African American) using the Financial Capacity Instrument (FCI). In a series of linear regression models, we examined the effect of race on FCI performance and identified preliminary predictor variables that mediated observed racial differences on the FCI. Prior/premorbid abilities were identified. Predictor variables examined in the models included race and other demographic factors (age, education, sex), performance on global cognitive measures (MMSE, DRS-2 Total Score), history of cardiovascular disease (hypertension, diabetes, hypercholesterolemia), and a measure of educational achievement (WRAT-3 Arithmetic). African American patients with MCI performed below white patients with MCI on 6 of the 7 FCI domains examined and on the FCI total score. WRAT-3 Arithmetic emerged as a partial mediator of group differences on the FCI, accounting for 54% of variance. In contrast, performance on global cognitive measures and history of cardiovascular disease only accounted for 14% and 2%, respectively, of the variance. Racial disparities in financial capacity seem to exist among patients with amnestic MCI. Basic academic math skills related to educational opportunity and quality of education account for a substantial proportion of the group difference in financial performance.

Reading comprehension skills of young adults with childhood diagnoses of dyslexia.

PubMed

Ransby, Marilyn J; Swanson, H Lee

2003-01-01

This study explores the contribution of cognitive processes to comprehension skills in adults who suffered from childhood developmental dyslexia (CD). The performance of adults with CD (ages 17 to 23), chronological age-matched (CA) adults, and reading level-matched (RL) children was compared on measures of phonological processing, naming speed, working memory (WM), general knowledge, vocabulary, and comprehension. The results showed that adults with CD scored lower on measures of phonological processing, naming speed, WM, general knowledge, and vocabulary when compared to CA readers but were comparable to RL children on the majority of process measures. Phonological processing, naming speed, vocabulary, general knowledge, and listening comprehension contributed independent variance to reading comprehension accuracy, whereas WM, intelligence, phonological processing, and listening comprehension contributed independent variance to comprehension fluency. Adults with CD scored lower than CA adults and higher than RL children on measures of lexical processing, WM, and listening comprehension when word recognition and intelligence were partialed from the analysis. In summary, constraints in phonological processing and naming speed mediate only some of the influence of high-order processes on reading comprehension. Furthermore, adults with CD experience difficulties in WM, listening comprehension, and vocabulary independently of their word recognition problems and intellectual ability.

Psychosocial factors associated with intended use of automated vehicles: A simulated driving study.

PubMed

Buckley, Lisa; Kaye, Sherrie-Anne; Pradhan, Anuj K

2018-06-01

This study applied the Theory of Planned Behavior (TPB) and the Technology Acceptance Model (TAM) to assess drivers' intended use of automated vehicles (AVs) after undertaking a simulated driving task. In addition, this study explored the potential for trust to account for additional variance to the psychosocial factors in TPB and TAM. Seventy-four participants (51% female) aged between 25 and 64 years (M = 42.8, SD = 12.9) undertook a 20 min simulated experimental drive in which participants experienced periods of automated driving and manual control. A survey task followed. A hierarchical regression analysis revealed that TPB constructs; attitude toward the behavior, subjective norms, and perceived behavioral control, were significant predictors of intentions to use AV. In addition, there was partial support for the test of TAM, with ease of use (but not usefulness) predicting intended use of AV (SAE Level 3). Trust contributed variance to both models beyond TPB or TAM constructs. The findings provide an important insight into factors that might reflect intended use of vehicles that are primarily automated (longitudinal, lateral, and manoeuvre controls) but require and allow drivers to have periods of manual control. Copyright © 2018 Elsevier Ltd. All rights reserved.

Relationship between theory of mind and functional independence is mediated by executive function.

PubMed

Ahmed, Fayeza S; Miller, L Stephen

2013-06-01

Theory of mind (ToM) is the ability to comprehend another person's perspective. Although there is much literature of ToM in children, there is a limited and somewhat inconclusive amount of studies examining ToM in a geriatric population. This study examined ToM's relationship to functional independence. Two tests of ToM, tests of executive function, and a measure of functional ability were administered to cognitively intact older adults. Results showed that 1 test of ToM (Strange Stories test) significantly accounted for variance in functional ability, whereas the other did not (Faux Pas test). In addition, Strange Stories test performance was partially driven by a verbal abstraction-based executive function: proverb interpretation. A multiple mediation model was employed to examine whether executive functions explained the relationship between the Strange Stories test and functional ability. Results showed that both the combined and individual indirect effects of the executive function measures mediated the relationship. We argue that, although components of ToM are associated with functional independence, ToM does not appear to account for additional variance in functional independence beyond executive function measures. PsycINFO Database Record (c) 2013 APA, all rights reserved.

The role of lexical variables in the visual recognition of Chinese characters: A megastudy analysis.

PubMed

Sze, Wei Ping; Yap, Melvin J; Rickard Liow, Susan J

2015-01-01

Logographic Chinese orthography partially represents both phonology and semantics. By capturing the online processing of a large pool of Chinese characters, we were able to examine the relative salience of specific lexical variables when this nonalphabetic script is read. Using a sample of native mainland Chinese speakers (N = 35), lexical decision latencies for 1560 single characters were collated into a database, before the effects of a comprehensive range of variables were explored. Hierarchical regression analyses determined the unique item-level variance explained by orthographic (frequency, stroke count), semantic (age of learning, imageability, number of meanings), and phonological (consistency, phonological frequency) factors. Orthographic and semantic variables, respectively, accounted for more collective variance than the phonological variables. Significant main effects were further observed for the individual orthographic and semantic predictors. These results are consistent with the idea that skilled readers tend to rely on orthographic and semantic information when processing visually presented characters. This megastudy approach marks an important extension to existing work on Chinese character recognition, which hitherto has relied on factorial designs. Collectively, the findings reported here represent a useful set of empirical constraints for future computational models of character recognition.

A longitudinal examination of the influence of maturation on physical self-perceptions and the relationship with physical activity in early adolescent girls.

PubMed

Knowles, Ann-Marie; Niven, Ailsa G; Fawkner, Samantha G; Henretty, Joan M

2009-06-01

This longitudinal study investigated the influence of maturation on physical self-perceptions and the relationship with physical activity in early adolescent girls (N=150; mean age=12.79+/-0.31). Physical characteristics were measured and participants completed the Physical Activity Questionnaire for Children, the Children and Youth Physical Self-Perception Profile and the Pubertal Development Scale on two occasions 12 months apart. The results demonstrated a decrease in overall physical activity levels over 12 months which was not influenced by maturational status or physical characteristics. Additional analysis indicated that physical self-perceptions partially accounted for the explained variance in physical activity change, with physical condition being an important individual predictor of physical activity. Further analysis indicated that body mass was an important individual predictor of changes in perceptions of body attractiveness and physical self-worth. At this age maturation has a limited influence on the physical activity behaviours of early adolescent girls and although the variance in physical activity was partly accounted for by physical self-perceptions, this was a relatively small contribution and other factors related to this drop in physical activity need to be considered longitudinally.

Factorial Validity and Invariance Assessment of a Short Version of the Recalled Childhood Gender Identity/Role Questionnaire.

PubMed

Veale, Jaimie F

2016-04-01

Recalled childhood gender role/identity is a construct that is related to sexual orientation, abuse, and psychological health. The purpose of this study was to assess the factorial validity of a short version of Zucker et al.'s (2006) "Recalled Childhood Gender Identity/Gender Role Questionnaire" using confirmatory factor analysis and to test the stability of the factor structure across groups (measurement invariance). Six items of the questionnaire were completed online by 1929 participants from a variety of gender identity and sexual orientation groups. Models of the six items loading onto one factor had poor fit for the data. Items were removed for having a large proportion of error variance. Among birth-assigned females, a five-item model had good fit for the data, but there was evidence for differences in scale's factor structure across gender identity, age, level of education, and country groups. Among birth-assigned males, the resulting four-item model did not account for all of the relationship between variables, and modeling for this resulted in a model that was almost saturated. This model also had evidence of measurement variance across gender identity and sexual orientation groups. The models had good reliability and factor score determinacy. These findings suggest that results of previous studies that have assessed recalled childhood gender role/identity may have been susceptible to construct bias due to measurement variance across these groups. Future studies should assess measurement invariance between groups they are comparing, and if it is not found the issue can be addressed by removing variant indicators and/or applying a partial invariance model.

Validation Evidence of the Motivation for Teaching Scale in Secondary Education.

PubMed

Abós, Ángel; Sevil, Javier; Martín-Albo, José; Aibar, Alberto; García-González, Luis

2018-04-10

Grounded in self-determination theory, the aim of this study was to develop a scale with adequate psychometric properties to assess motivation for teaching and to explain some outcomes of secondary education teachers at work. The sample comprised 584 secondary education teachers. Analyses supported the five-factor model (intrinsic motivation, identified regulation, introjected regulation, external regulation and amotivation) and indicated the presence of a continuum of self-determination. Evidence of reliability was provided by Cronbach's alpha, composite reliability and average variance extracted. Multigroup confirmatory factor analyses supported the partial invariance (configural and metric) of the scale in different sub-samples, in terms of gender and type of school. Concurrent validity was analyzed by a structural equation modeling that explained 71% of the work dedication variance and 69% of the boredom at work variance. Work dedication was positively predicted by intrinsic motivation (ß = .56, p < .001) and external regulation (ß = .29, p < .001) and negatively predicted by introjected regulation (ß = -.22, p < .001) and amotivation (ß = -.49, p < .001). Boredom at work was negatively predicted by intrinsic motivation (ß = -.28, p < .005) and positively predicted by amotivation (ß = .68, p < .001). The Motivation for Teaching Scale in Secondary Education (Spanish acronym EME-ES, Escala de Motivación por la Enseñanza en Educación Secundaria) is discussed as a valid and reliable instrument. This is the first specific scale in the work context of secondary teachers that has integrated the five-factor structure together with their dedication and boredom at work.

Tri-Variate Relationships among Vegetation, Soil, and Topography along Gradients of Fluvial Biogeomorphic Succession

PubMed Central

Kim, Daehyun; Kupfer, John A.

2016-01-01

This research investigated how the strength of vegetation–soil–topography couplings varied along a gradient of biogeomorphic succession in two distinct fluvial systems: a forested river floodplain and a coastal salt marsh creek. The strength of couplings was quantified as tri-variance, which was calculated by correlating three singular axes, one each extracted using three-block partial least squares from vegetation, soil, and topography data blocks. Within each system, tri-variance was examined at low-, mid-, and high-elevation sites, which represented early-, intermediate-, and late-successional phases, respectively, and corresponded to differences in ongoing disturbance frequency and intensity. Both systems exhibited clearly increasing tri-variance from the early- to late-successional stages. The lowest-lying sites underwent frequent and intense hydrogeomorphic forcings that dynamically reworked soil substrates, restructured surface landforms, and controlled the colonization of plant species. Such conditions led vegetation, soil, and topography to show discrete, stochastic, and individualistic behaviors over space and time, resulting in a loose coupling among the three ecosystem components. In the highest-elevation sites, in contrast, disturbances that might disrupt the existing biotic–abiotic relationships were less common. Hence, ecological succession, soil-forming processes, and landform evolution occurred in tight conjunction with one another over a prolonged period, thereby strengthening couplings among them; namely, the three behaved in unity over space and time. We propose that the recurrence interval of physical disturbance is important to—and potentially serves as an indicator of—the intensity and mechanisms of vegetation–soil–topography feedbacks in fluvial biogeomorphic systems. PMID:27649497

Applying the social cognitive perspective to volunteer intention in China: the mediating roles of self-efficacy and motivation.

PubMed

Wang, Ji-Wei; Wei, Chang-Nian; Harada, Koichi; Minamoto, Keiko; Ueda, Kimiyo; Cui, Hong-Wei; Zhang, Cheng-Gang; Cui, Zhi-Ting; Ueda, Atsushi

2011-06-01

When predicting volunteer intention, much attention is paid to the volunteer organization environment (VOE). Given that self-efficacy and motivation have emerged as important predictors of volunteer intention, we adopted a combination of ideas of Bandura's social cognitive theory and Ajzen's theory of planned behavior integrating VOE, self-efficacy and motivation to examine their effects on volunteer intention and to determine whether self-efficacy and motivation mediate the relationship between VOE and volunteer intention. The subjects of this study consisted of 198 community health volunteers in Shanghai city, China. Exploratory factor analysis was performed to identify the factor structure using standard principal component analysis. Six new factors were revealed, including two VOE factors, relation with organization and support from government; two motivation factors, personal attitude and social recognition; self-efficacy and volunteer intention. The results of a hierarchical regression analysis indicated that relation with organization accounted for 14.8% of the variance in volunteer intention, and support from government failed to add significantly to variance in volunteer intention; self-efficacy and personal attitude motivation partially mediated the effects of relation with organization on volunteer intention; social recognition motivation did not mediate the relationship between relation with organization and volunteer intention; and relation with organization, self-efficacy and personal attitude motivation accounted for 33.7% of the variance in volunteer intention. These results provide support for self-efficacy and personal attitude motivation as mediators and provide preliminary insight into the potential mechanisms for predicting volunteer intention and improving volunteering by integrating VOE, self-efficacy and motivation factors.

Superdiffusion in a non-Markovian random walk model with a Gaussian memory profile

NASA Astrophysics Data System (ADS)

Borges, G. M.; Ferreira, A. S.; da Silva, M. A. A.; Cressoni, J. C.; Viswanathan, G. M.; Mariz, A. M.

2012-09-01

Most superdiffusive Non-Markovian random walk models assume that correlations are maintained at all time scales, e.g., fractional Brownian motion, Lévy walks, the Elephant walk and Alzheimer walk models. In the latter two models the random walker can always "remember" the initial times near t = 0. Assuming jump size distributions with finite variance, the question naturally arises: is superdiffusion possible if the walker is unable to recall the initial times? We give a conclusive answer to this general question, by studying a non-Markovian model in which the walker's memory of the past is weighted by a Gaussian centered at time t/2, at which time the walker had one half the present age, and with a standard deviation σt which grows linearly as the walker ages. For large widths we find that the model behaves similarly to the Elephant model, but for small widths this Gaussian memory profile model behaves like the Alzheimer walk model. We also report that the phenomenon of amnestically induced persistence, known to occur in the Alzheimer walk model, arises in the Gaussian memory profile model. We conclude that memory of the initial times is not a necessary condition for generating (log-periodic) superdiffusion. We show that the phenomenon of amnestically induced persistence extends to the case of a Gaussian memory profile.

Partial volume correction of brain perfusion estimates using the inherent signal data of time-resolved arterial spin labeling.

PubMed

Ahlgren, André; Wirestam, Ronnie; Petersen, Esben Thade; Ståhlberg, Freddy; Knutsson, Linda

2014-09-01

Quantitative perfusion MRI based on arterial spin labeling (ASL) is hampered by partial volume effects (PVEs), arising due to voxel signal cross-contamination between different compartments. To address this issue, several partial volume correction (PVC) methods have been presented. Most previous methods rely on segmentation of a high-resolution T1 -weighted morphological image volume that is coregistered to the low-resolution ASL data, making the result sensitive to errors in the segmentation and coregistration. In this work, we present a methodology for partial volume estimation and correction, using only low-resolution ASL data acquired with the QUASAR sequence. The methodology consists of a T1 -based segmentation method, with no spatial priors, and a modified PVC method based on linear regression. The presented approach thus avoids prior assumptions about the spatial distribution of brain compartments, while also avoiding coregistration between different image volumes. Simulations based on a digital phantom as well as in vivo measurements in 10 volunteers were used to assess the performance of the proposed segmentation approach. The simulation results indicated that QUASAR data can be used for robust partial volume estimation, and this was confirmed by the in vivo experiments. The proposed PVC method yielded probable perfusion maps, comparable to a reference method based on segmentation of a high-resolution morphological scan. Corrected gray matter (GM) perfusion was 47% higher than uncorrected values, suggesting a significant amount of PVEs in the data. Whereas the reference method failed to completely eliminate the dependence of perfusion estimates on the volume fraction, the novel approach produced GM perfusion values independent of GM volume fraction. The intra-subject coefficient of variation of corrected perfusion values was lowest for the proposed PVC method. As shown in this work, low-resolution partial volume estimation in connection with ASL perfusion estimation is feasible, and provides a promising tool for decoupling perfusion and tissue volume. Copyright © 2014 John Wiley & Sons, Ltd.

Investigating the effect of nurse-team communication on nurse turnover: relationships among communication processes, identification, and intent to leave.

PubMed

Apker, Julie; Propp, Kathleen M; Ford, Wendy S Zabava

2009-03-01

Enhanced team communication may strengthen nurses' attachment to their organizations and teams and improve nurse retention. This study examines the relationships among nurse-team communication, identification (organizational and team), and intent to leave. Hospital nurses (N = 201) completed surveys measuring 3 nurse-team communication processes: promoting team synergy, ensuring quality decisions, and individualizing communication. Hierarchical regression analyses revealed that promoting team synergy was a significant predictor of intent to leave, whereas ensuring quality decisions and individualizing communication did not account for significant additional variance in intent to leave. Separate analyses showed that the relationship between promoting team synergy and intent to leave was partially mediated by team identification or by organizational identification. Further analyses were conducted on the 7 communication practices for promoting team synergy. Mentoring emerged as the only significant predictor of intent to leave; however, its relationship to intent to leave was fully mediated by organizational identification or partially mediated by team identification. Pragmatic suggestions are offered to improve nurse identification and reduce turnover.

Partial Least Squares Based Gene Expression Analysis in EBV- Positive and EBV-Negative Posttransplant Lymphoproliferative Disorders.

PubMed

Wu, Sa; Zhang, Xin; Li, Zhi-Ming; Shi, Yan-Xia; Huang, Jia-Jia; Xia, Yi; Yang, Hang; Jiang, Wen-Qi

2013-01-01

Post-transplant lymphoproliferative disorder (PTLD) is a common complication of therapeutic immunosuppression after organ transplantation. Gene expression profile facilitates the identification of biological difference between Epstein-Barr virus (EBV) positive and negative PTLDs. Previous studies mainly implemented variance/regression analysis without considering unaccounted array specific factors. The aim of this study is to investigate the gene expression difference between EBV positive and negative PTLDs through partial least squares (PLS) based analysis. With a microarray data set from the Gene Expression Omnibus database, we performed PLS based analysis. We acquired 1188 differentially expressed genes. Pathway and Gene Ontology enrichment analysis identified significantly over-representation of dysregulated genes in immune response and cancer related biological processes. Network analysis identified three hub genes with degrees higher than 15, including CREBBP, ATXN1, and PML. Proteins encoded by CREBBP and PML have been reported to be interact with EBV before. Our findings shed light on expression distinction of EBV positive and negative PTLDs with the hope to offer theoretical support for future therapeutic study.

Convolutional neural networks based on augmented training samples for synthetic aperture radar target recognition

NASA Astrophysics Data System (ADS)

Yan, Yue

2018-03-01

A synthetic aperture radar (SAR) automatic target recognition (ATR) method based on the convolutional neural networks (CNN) trained by augmented training samples is proposed. To enhance the robustness of CNN to various extended operating conditions (EOCs), the original training images are used to generate the noisy samples at different signal-to-noise ratios (SNRs), multiresolution representations, and partially occluded images. Then, the generated images together with the original ones are used to train a designed CNN for target recognition. The augmented training samples can contrapuntally improve the robustness of the trained CNN to the covered EOCs, i.e., the noise corruption, resolution variance, and partial occlusion. Moreover, the significantly larger training set effectively enhances the representation capability for other conditions, e.g., the standard operating condition (SOC), as well as the stability of the network. Therefore, better performance can be achieved by the proposed method for SAR ATR. For experimental evaluation, extensive experiments are conducted on the Moving and Stationary Target Acquisition and Recognition dataset under SOC and several typical EOCs.

ADL ability characteristics of partially dependent older people: Gender and age differences in ADL ability.

PubMed

Sato, S; Demura, S; Tanaka, K; Kasuga, K; Kobayashi, H

2001-07-01

Age and gender differences in ADL ability were investigated using 568 Japanese partially dependent older people (PD, Mean age=82.2±7.76 years) living in welfare institutions. The subjects were asked about 17 ADL items representing 7 ADL domains by the professional staff working at subjects' institutions. Each item was assessed by a dichotomous scale of "possible" or "impossible". Item proportions of "possible" response were calculated for gender and age groups (60s, 70s, 80s and 90s). Two-way analysis of variance (ANOVA) using the arcsine transformation method indicated no gender differences. Significant decreases in ADL ability with aging were found in 13 of the 17 items. The dependency of ADL in the PD significantly increases with aging, and there is no significant difference in this trend between men and women. The dependency of more difficult activities using lower limb increase from the 70s, and independency of low-difficult activities such as manual activities, feeding and changing posture while lying is maintained until the 80s and over.

Culture beats gender? The importance of controlling for identity- and parenting-related risk factors in adolescent psychopathology.

PubMed

Seiffge-Krenke, Inge; Persike, Malte; Besevegis, Elias; Chau, Cecilia; Karaman, Neslihan Güney; Lannegrand-Willems, Lyda; Lubiewska, Katharzyna; Rohail, Iffat

2018-02-01

This study analyzed the unique effects of gender and culture on psychopathology in adolescents from seven countries after controlling for factors which might have contributed to variations in psychopathology. In a sample 2259 adolescents (M = 15 years; 54% female) from France, Germany, Turkey, Greece, Peru, Pakistan, and Poland identity stress, coping with identity stress, maternal parenting (support, psychological control, anxious rearing) and psychopathology (internalizing, externalizing and total symptomatology) were assessed. Due to variations in stress perception, coping style and maternal behavior, these covariates were partialed out before the psychopathology scores were subjected to analyses of variance with gender and country as factors. These analyses leveled out the main effect of country and revealed country-specific gender effects. In four countries, males reported higher internalizing and total symptomatology than females. Partialing out the covariates resulted in a clearer picture of culture-specific and gender-dependent effects on psychopathology, which is helpful in designing interventions. Copyright © 2017 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Comparative study of circumferential clasp retention force for titanium and cobalt-chromium removable partial dentures.

PubMed

Rodrigues, Renata Cristina Silveira; Ribeiro, Ricardo Faria; de Mattos, Maria da Gloria Chiarello; Bezzon, Osvaldo Luiz

2002-09-01

The interest in using titanium to fabricate removable partial denture (RPD) frameworks has increased, but there are few studies to support its use. The objective of this study was to compare circumferential RPD clasps made of commercially pure titanium and identical clasps made of 2 different cobalt (Co)-chromium (Cr) alloys by testing insertion/removal and radiographically inspecting the casts for defects. On refractory casts that represent a partially edentulous mandibular right hemi-arch segment, 36 frameworks were cast from commercially pure titanium (n = 12) and 2 Co-Cr alloys (n = 12 each) with identical prefabricated patterns and the manufacturer-designated investment and casting technique. Each group was divided into 2 subgroups, corresponding to .25-mm and .50-mm undercuts, respectively. No polishing procedures were performed to ensure uniformity. Only nodules and burs were carefully removed with tungsten burs under magnification when necessary. The specimens were radiographed and subjected to an insertion/removal test simulating 5 years of framework use. The data were subjected to analysis of variance and the Tukey complementary test (P<.01) to compare the retentive forces of RPDs made with the different materials. The Student t test (P<.01) was used to compare the retentive forces of RPDs fabricated with the same alloy with different undercuts. A total of 20% of the titanium specimens demonstrated porosity, showing casting difficulties, and any defect detected on the clasps determined the sample replacement. For Co-Cr alloys, casting difficulties were not found. The data were subjected to analysis of variance and the Tukey complementary test to compare materials for the same undercut. For the .25-mm undercut, no significant difference was found between Magnum and Rematitan alloys; they were both different from the Remanium alloy (P<.01). For the.50-mm undercut, no significant difference was found between Co-Cr alloys; they were both different from Rematitan alloy (P<.01). The Student t test used to compare the same alloys with different undercuts showed no significant difference between Remanium with .25-mm and .50-mm undercuts. For Magnum and Rematitan alloys, there was a significant difference between different undercuts (P=.01). Within the limitations of this simulation study, the results suggest that commercially pure titanium clasps maintained retention over a simulated 5-year period, with lower retention force than identical Co-Cr clasps.

Sea-level haemoglobin concentration is associated with greater exercise capacity in Tibetan males at 4200 m.

PubMed

Wagner, P D; Simonson, T S; Wei, G; Wagner, H E; Wuren, T; Qin, G; Yan, M; Ge, R L

2015-11-01

What is the topic of this review? Recent developments link relatively lower hemoglobin concentration in Tibetans at high altitude to exercise capacity and components of oxygen transport. What advances does it highlight? Haemoglobin concentration (ranging from 15.2 to 22.9 g dl(-1) ) in Tibetan males was negatively associated with peak oxygen (O2 ) uptake per kilogram, cardiac output and muscle O2 diffusion conductance. Most variance in the peak O2 uptake per kilogram of Tibetan males was attributed to cardiac output, muscle diffusional conductance and arterial partial pressure of CO2 . The mechanisms underlying these differences in oxygen transport in Tibetans require additional analyses. Despite residence at >4000 m above sea level, many Tibetan highlanders, unlike Andean counterparts and lowlanders at altitude, exhibit haemoglobin concentration ([Hb]) within the typical sea-level range. Genetic adaptations in Tibetans are associated with this relatively low [Hb], yet the functional relevance of the lower [Hb] remains unknown. To address this, we examined each major step of the oxygen transport cascade [ventilation (VE), cardiac output (QT) and diffusional conductance in lung (DL) and muscle (DM)] in Tibetan males at maximal exercise on a cycle ergometer. Ranging from 15.2 to 22.9 g dl(-1) , [Hb] was negatively associated with peak O2 uptake per kilogram (r = -0.45, P < 0.05) and both cardiac output (QT/kg: r = -0.54, P < 0.02) and muscle O2 diffusion conductance (DM/kg: r = -0.44, P < 0.05) but not ventilation, arterial partial pressure of O2 or pulmonary diffusing capacity. Most variance in peak O2 uptake per kilogram was attributed to QT, DM and arterial partial pressure of CO2 (r(2)  = 0.90). In summary, lack of polycythaemia in Tibetans is associated with increased exercise capacity, which is explained by elevated cardiac, muscle and, to a small extent, ventilatory responses rather than pulmonary gas exchange. Whether lower [Hb] is the cause or result of these changes in O2 transport or is causally unrelated will require additional study. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

The Contribution of Agreeableness and Self-efficacy Beliefs to Prosociality

PubMed Central

CAPRARA, GIAN VITTORIO; ALESSANDRI, GUIDO; DI GIUNTA, LAURA; PANERAI, LAURA; EISENBERG, NANCY

2010-01-01

The present study examined how agreeableness and self-efficacy beliefs about responding empathically to others’ needs predict individuals’ prosociality across time. Participants were 377 adolescents (66% males) aged 16 at Time 1 and 18 at Time 2 who took part at this study. Measures of agreeableness, empathic self-efficacy and prosociality were collected at two time points. The findings corroborated the posited paths of relations to assigning agreeableness a major role in predicting the level of individuals’ prosociality. Empathic self-efficacy beliefs partially mediated the relation of agreeableness to prosociality. The posited conceptual model accounted for a significant portion of variance in prosociality and provides guidance with respect to interventions aimed at promoting prosociality. PMID:20592954

Remission of Maternal Depression: Relations to Family Functioning and Youth Internalizing and Externalizing Symptoms

PubMed Central

Foster, Cynthia Ewell; Webster, Melissa C.; Weissman, Myrna M.; Pilowsky, Daniel J.; Wickramaratne, Priya J.; Talati, Ardesheer; Rush, A. John; Hughes, Carroll W.; Garber, Judy; Malloy, Erin; Cerda, Gabrielle; Kornstein, Susan G.; Alpert, Jonathan E.; Wisniewski, Stephen R.; Trivedi, Madhukar H.; Fava, Maurizio; King, Cheryl A.

2009-01-01

Family functioning and parenting were hypothesized to mediate the relation between remission of maternal depression and children's psychosocial adjustment. Participants were 114 mother-child dyads participating in the Sequenced Treatment Alternatives to Relieve Depression Child 3-month follow-up. All mothers had been diagnosed with major depressive disorder and were treated initially with citalopram; 33% of mothers experienced remission of depressive symptoms. Youth ranged in age from 7 to 17. Remission of maternal depression was associated with changes in children's reports of their mothers' warmth/acceptance, which in turn partially mediated the relation between maternal depression remission and youth internalizing symptoms, accounting for 22.9% of the variance. PMID:18991123

Electron Heating at Kinetic Scales in Magnetosheath Turbulence

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

Chasapis, Alexandros; Matthaeus, W. H.; Parashar, T. N.

2017-02-20

We present a statistical study of coherent structures at kinetic scales, using data from the Magnetospheric Multiscale mission in the Earth’s magnetosheath. We implemented the multi-spacecraft partial variance of increments (PVI) technique to detect these structures, which are associated with intermittency at kinetic scales. We examine the properties of the electron heating occurring within such structures. We find that, statistically, structures with a high PVI index are regions of significant electron heating. We also focus on one such structure, a current sheet, which shows some signatures consistent with magnetic reconnection. Strong parallel electron heating coincides with whistler emissions at themore » edges of the current sheet.« less

Glutamate-Bound NMDARs Arising from In Vivo-like Network Activity Extend Spatio-temporal Integration in a L5 Cortical Pyramidal Cell Model

PubMed Central

Farinella, Matteo; Ruedt, Daniel T.; Gleeson, Padraig; Lanore, Frederic; Silver, R. Angus

2014-01-01

In vivo, cortical pyramidal cells are bombarded by asynchronous synaptic input arising from ongoing network activity. However, little is known about how such ‘background’ synaptic input interacts with nonlinear dendritic mechanisms. We have modified an existing model of a layer 5 (L5) pyramidal cell to explore how dendritic integration in the apical dendritic tuft could be altered by the levels of network activity observed in vivo. Here we show that asynchronous background excitatory input increases neuronal gain and extends both temporal and spatial integration of stimulus-evoked synaptic input onto the dendritic tuft. Addition of fast and slow inhibitory synaptic conductances, with properties similar to those from dendritic targeting interneurons, that provided a ‘balanced’ background configuration, partially counteracted these effects, suggesting that inhibition can tune spatio-temporal integration in the tuft. Excitatory background input lowered the threshold for NMDA receptor-mediated dendritic spikes, extended their duration and increased the probability of additional regenerative events occurring in neighbouring branches. These effects were also observed in a passive model where all the non-synaptic voltage-gated conductances were removed. Our results show that glutamate-bound NMDA receptors arising from ongoing network activity can provide a powerful spatially distributed nonlinear dendritic conductance. This may enable L5 pyramidal cells to change their integrative properties as a function of local network activity, potentially allowing both clustered and spatially distributed synaptic inputs to be integrated over extended timescales. PMID:24763087

Fundamental Flaws In The Derivation Of Stevens' Law For Taste Within Norwich's Entropy Theory of Perception

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

Nizami, Lance

2010-03-01

Norwich's Entropy Theory of Perception (1975-present) is a general theory of perception, based on Shannon's Information Theory. Among many bold claims, the Entropy Theory presents a truly astounding result: that Stevens' Law with an Index of 1, an empirical power relation of direct proportionality between perceived taste intensity and stimulus concentration, arises from theory alone. Norwich's theorizing starts with several extraordinary hypotheses. First, 'multiple, parallel receptor-neuron units' without collaterals 'carry essentially the same message to the brain', i.e. the rate-level curves are identical. Second, sensation is proportional to firing rate. Third, firing rate is proportional to the taste receptor's 'resolvablemore » uncertainty'. Fourth, the 'resolvable uncertainty' is obtained from Shannon's Information Theory. Finally, 'resolvable uncertainty' also depends upon the microscopic thermodynamic density fluctuation of the tasted solute. Norwich proves that density fluctuation is density variance, which is proportional to solute concentration, all based on the theory of fluctuations in fluid composition from Tolman's classic physics text, 'The Principles of Statistical Mechanics'. Altogether, according to Norwich, perceived taste intensity is theoretically proportional to solute concentration. Such a universal rule for taste, one that is independent of solute identity, personal physiological differences, and psychophysical task, is truly remarkable and is well-deserving of scrutiny. Norwich's crucial step was the derivation of density variance. That step was meticulously reconstructed here. It transpires that the appropriate fluctuation is Tolman's mean-square fractional density fluctuation, not density variance as used by Norwich. Tolman's algebra yields a 'Stevens Index' of -1 rather than 1. As 'Stevens Index' empirically always exceeds zero, the Index of -1 suggests that it is risky to infer psychophysical laws of sensory response from information theory and stimulus physics while ignoring empirical biological transformations, such as sensory transduction. Indeed, it raises doubts as to whether the Entropy Theory actually describes psychophysical laws at all.« less

An Ensemble Approach to Understanding the ENSO Response to Climate Change

NASA Astrophysics Data System (ADS)

Stevenson, S.; Capotondi, A.; Fasullo, J.; Otto-Bliesner, B. L.

2017-12-01

The dynamics of the El Nino/Southern Oscillation (ENSO) are known to be sensitive to changes in background climate conditions, as well as atmosphere/ocean feedbacks. However, the degree to which shifts in ENSO characteristics can be robustly attributed to external climate forcings remains unknown. Efforts to assess these changes in a multi-model framework are subject to uncertainties due to both differing model physics and internal ENSO variability. New community ensembles created at the National Center for Atmospheric Research and the NOAA Geophysical Fluid Dynamics Laboratory are ideally suited to addressing this problem, providing many realizations of the climate of the 850-2100 period with a combination of both natural and anthropogenic climate forcing factors. Here we analyze the impacts of external forcing on El Nino and La Nina evolution using four sets of simulations: the CESM Last Millennium Ensemble (CESM-LME), which covers the 850-2005 period and provides long-term context for forced responses; the Large Ensemble (CESM-LE), which includes 20th century and 21st century (RCP8.5) projections; the Medium Ensemble (CESM-ME), which is composed of 21st century RCP4.5 projections; and a large ensemble with the GFDL ESM2M, which includes 20th century and RCP8.5 projections. In the CESM, ENSO variance increases slightly over the 20th century in all ensembles, with the effects becoming much larger during the 21st. The slower increase in variance over the 20th century is shown to arise from compensating influences from greenhouse gas (GHG) and anthropogenic aerosol emissions, which give way to GHG-dominated effects by 2100. However, the 21st century variance increase is not robust: CESM and the ESM2M differ drastically in their ENSO projections. The mechanisms for these inter-model differences are discussed, as are the implications for the design of future multi-model ENSO projection experiments.

A population genetic interpretation of GWAS findings for human quantitative traits

PubMed Central

Bullaughey, Kevin; Hudson, Richard R.; Sella, Guy

2018-01-01

Human genome-wide association studies (GWASs) are revealing the genetic architecture of anthropomorphic and biomedical traits, i.e., the frequencies and effect sizes of variants that contribute to heritable variation in a trait. To interpret these findings, we need to understand how genetic architecture is shaped by basic population genetics processes—notably, by mutation, natural selection, and genetic drift. Because many quantitative traits are subject to stabilizing selection and because genetic variation that affects one trait often affects many others, we model the genetic architecture of a focal trait that arises under stabilizing selection in a multidimensional trait space. We solve the model for the phenotypic distribution and allelic dynamics at steady state and derive robust, closed-form solutions for summary statistics of the genetic architecture. Our results provide a simple interpretation for missing heritability and why it varies among traits. They predict that the distribution of variances contributed by loci identified in GWASs is well approximated by a simple functional form that depends on a single parameter: the expected contribution to genetic variance of a strongly selected site affecting the trait. We test this prediction against the results of GWASs for height and body mass index (BMI) and find that it fits the data well, allowing us to make inferences about the degree of pleiotropy and mutational target size for these traits. Our findings help to explain why the GWAS for height explains more of the heritable variance than the similarly sized GWAS for BMI and to predict the increase in explained heritability with study sample size. Considering the demographic history of European populations, in which these GWASs were performed, we further find that most of the associations they identified likely involve mutations that arose shortly before or during the Out-of-Africa bottleneck at sites with selection coefficients around s = 10−3. PMID:29547617

A note on the regularity of solutions of infinite dimensional Riccati equations

NASA Technical Reports Server (NTRS)

Burns, John A.; King, Belinda B.

1994-01-01

This note is concerned with the regularity of solutions of algebraic Riccati equations arising from infinite dimensional LQR and LQG control problems. We show that distributed parameter systems described by certain parabolic partial differential equations often have a special structure that smoothes solutions of the corresponding Riccati equation. This analysis is motivated by the need to find specific representations for Riccati operators that can be used in the development of computational schemes for problems where the input and output operators are not Hilbert-Schmidt. This situation occurs in many boundary control problems and in certain distributed control problems associated with optimal sensor/actuator placement.

High Si-H local mode overtones in SiHD/sub 3/

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

Bernheim, R.A.; Lampe, F.W.; O'Keefe, J.F.

1984-01-01

Spectra for SiHD/sub 3/ obtained using a nonresonant photoacoustic cell mounted within the cavity of a CR490 tunable CW laser are reported herein. The symmetric top spectra exhibit partial rotational resolution. A relation for determining the Si-H bond distance is reported, and the Si-D bond distance is taken to be the same as the Si-H distance in the ground vibrational state. The bond angle is assumed to remain tetrahedral in both situations. The noted spectral vibrational band widths arise only from rotational structure with contributions from fast vibrational relaxation not being evident. 10 references, 2 figures, 1 table.

Partial insanity: when the judiciary and the psychiatric world collide.

PubMed

Altmark, D; Sigal, M; Gelkopf, M

1995-01-01

The psychiatric and judicial concepts of mental disorders are similar but not always identical. The gap between them creates confusion, a lack of unity and inconsistencies in decision making. This gap needs to be bridged. In the hinterland of these concepts lies a range of psychiatric disturbances such as encapsulated over organized delusional disorders (Paranoia Vera) and life endangering eating disorders (Anorexia Nervosa). When life threatening or criminal responsibility circumstances arise, the dilemma presented to the psychiatrists on the one hand and the judicial system on the other reaches its peak. Presented in the article are aspects of the gray areas of involuntary commitment and criminal responsibility.

On the mathematical foundations of mutually unbiased bases

NASA Astrophysics Data System (ADS)

Thas, Koen

2018-02-01

In order to describe a setting to handle Zauner's conjecture on mutually unbiased bases (MUBs) (stating that in C^d, a set of MUBs of the theoretical maximal size d + 1 exists only if d is a prime power), we pose some fundamental questions which naturally arise. Some of these questions have important consequences for the construction theory of (new) sets of maximal MUBs. Partial answers will be provided in particular cases; more specifically, we will analyze MUBs with associated operator groups that have nilpotence class 2, and consider MUBs of height 1. We will also confirm Zauner's conjecture for MUBs with associated finite nilpotent operator groups.

An attempt to localize and identify the gravity sensing mechanism of plants

NASA Technical Reports Server (NTRS)

Bandurski, R. S.; Schulze, A.; Reinecke, D.

1985-01-01

The oxidation and transport of indole-3-acetic acid (IAA) in Zea mays is examined towards an understanding of the gravity-influenced promotion of growth in plants. An enzyme that oxidizes IAA to a nongrowth-promoting species has been partially purified, and determined to be stimulated by a lipoidal factor. Data suggest that the upward transport of IAA in the stele and outward movement from the stele into the mesophyll cortex is metabolically mediated, and possibly affected by the gravitational stimulus. It is postulated that hormone assymmetries can arise by 'potential-gating' of the transport channels between the various plant tissues.

Polariton Chimeras: Bose-Einstein Condensates with Intrinsic Chaoticity and Spontaneous Long-Range Ordering

NASA Astrophysics Data System (ADS)

Gavrilov, S. S.

2018-01-01

The system of cavity polaritons driven by a plane electromagnetic wave is found to undergo the spontaneous breaking of spatial symmetry, which results in a lifted phase locking with respect to the driving field and, consequently, in the possibility of internal ordering. In particular, periodic spin and intensity patterns arise in polariton wires; they exhibit strong long-range order and can serve as media for signal transmission. Such patterns have the properties of dynamical chimeras: they are formed spontaneously in perfectly homogeneous media and can be partially chaotic. The reported new mechanism of chimera formation requires neither time-delayed feedback loops nor nonlocal interactions.

Bivariate spline solution of time dependent nonlinear PDE for a population density over irregular domains.

PubMed

Gutierrez, Juan B; Lai, Ming-Jun; Slavov, George

2015-12-01

We study a time dependent partial differential equation (PDE) which arises from classic models in ecology involving logistic growth with Allee effect by introducing a discrete weak solution. Existence, uniqueness and stability of the discrete weak solutions are discussed. We use bivariate splines to approximate the discrete weak solution of the nonlinear PDE. A computational algorithm is designed to solve this PDE. A convergence analysis of the algorithm is presented. We present some simulations of population development over some irregular domains. Finally, we discuss applications in epidemiology and other ecological problems. Copyright © 2015 Elsevier Inc. All rights reserved.

Model error estimation for distributed systems described by elliptic equations

NASA Technical Reports Server (NTRS)

Rodriguez, G.

1983-01-01

A function space approach is used to develop a theory for estimation of the errors inherent in an elliptic partial differential equation model for a distributed parameter system. By establishing knowledge of the inevitable deficiencies in the model, the error estimates provide a foundation for updating the model. The function space solution leads to a specification of a method for computation of the model error estimates and development of model error analysis techniques for comparison between actual and estimated errors. The paper summarizes the model error estimation approach as well as an application arising in the area of modeling for static shape determination of large flexible systems.

A partitioning strategy for nonuniform problems on multiprocessors

NASA Technical Reports Server (NTRS)

Berger, M. J.; Bokhari, S.

1985-01-01

The partitioning of a problem on a domain with unequal work estimates in different subddomains is considered in a way that balances the work load across multiple processors. Such a problem arises for example in solving partial differential equations using an adaptive method that places extra grid points in certain subregions of the domain. A binary decomposition of the domain is used to partition it into rectangles requiring equal computational effort. The communication costs of mapping this partitioning onto different microprocessors: a mesh-connected array, a tree machine and a hypercube is then studied. The communication cost expressions can be used to determine the optimal depth of the above partitioning.

The 1982 ultraviolet eclipse of the symbiotic binary AR Pav

NASA Technical Reports Server (NTRS)

Hutchings, J. B.; Cowley, A. P.; Ake, T. B.; Imhoff, C. L.

1983-01-01

Observations with the International Ultraviolet Explorer (IUE) of the symbiotic binary AR Pav through its 1982 eclipse show that the hot star is not eclipsed. The hot star is associated with an extended region of continuum emission which is partially eclipsed. The eclipsed radiation is hotter near to its center, with a maximum temperature of about 9000 K. The uneclipsed flux is hotter than this. UV emission lines are not measurably eclipsed and presumably arise in a much larger region than the continuum. These data provide new constraints on models of the system but also are apparently in contradiction to those based on ground-based data.

Voltera's Solution of the Wave Equation as Applied to Three-Dimensional Supersonic Airfoil Problems

NASA Technical Reports Server (NTRS)

Heslet, Max A; Lomax, Harvard; Jones, Arthur L

1947-01-01

A surface integral is developed which yields solutions of the linearized partial differential equation for supersonic flow. These solutions satisfy boundary conditions arising in wing theory. Particular applications of this general method are made, using acceleration potentials, to flat surfaces and to uniformly loaded lifting surfaces. Rectangular and trapezoidal plan forms are considered along with triangular forms adaptable to swept-forward and swept-back wings. The case of the triangular plan form in sideslip is also included. Emphasis is placed on the systematic application of the method to the lifting surfaces considered and on the possibility of further application.

Topographic Change of the Dichotomy Boundary Suggested by Crustal Inversion

NASA Technical Reports Server (NTRS)

Neumann, G. A.

2004-01-01

Linear negative gravity anomalies in Acidalia Planitia along the eastern edge of Tempe Terra and along the northern edge of Arabia Terra have been noted in Mars Global Surveyor gravity fields. Once proposed to represent buried fluvial channels, it is now believed that these gravity troughs mainly arise from partial compensation of the hemispheric dichotomy topographic scarp. A recent inversion for crustal structure finds that mantle compensation of the scarp is offset from the present-day topographic expression of the dichotomy boundary. The offset suggests that erosion or other forms of mass wasting occurred after lithosphere thickened and no longer accomodated topographic change through viscous relaxation.

A classical Perron method for existence of smooth solutions to boundary value and obstacle problems for degenerate-elliptic operators via holomorphic maps

NASA Astrophysics Data System (ADS)

Feehan, Paul M. N.

2017-09-01

We prove existence of solutions to boundary value problems and obstacle problems for degenerate-elliptic, linear, second-order partial differential operators with partial Dirichlet boundary conditions using a new version of the Perron method. The elliptic operators considered have a degeneracy along a portion of the domain boundary which is similar to the degeneracy of a model linear operator identified by Daskalopoulos and Hamilton [9] in their study of the porous medium equation or the degeneracy of the Heston operator [21] in mathematical finance. Existence of a solution to the partial Dirichlet problem on a half-ball, where the operator becomes degenerate on the flat boundary and a Dirichlet condition is only imposed on the spherical boundary, provides the key additional ingredient required for our Perron method. Surprisingly, proving existence of a solution to this partial Dirichlet problem with ;mixed; boundary conditions on a half-ball is more challenging than one might expect. Due to the difficulty in developing a global Schauder estimate and due to compatibility conditions arising where the ;degenerate; and ;non-degenerate boundaries; touch, one cannot directly apply the continuity or approximate solution methods. However, in dimension two, there is a holomorphic map from the half-disk onto the infinite strip in the complex plane and one can extend this definition to higher dimensions to give a diffeomorphism from the half-ball onto the infinite ;slab;. The solution to the partial Dirichlet problem on the half-ball can thus be converted to a partial Dirichlet problem on the slab, albeit for an operator which now has exponentially growing coefficients. The required Schauder regularity theory and existence of a solution to the partial Dirichlet problem on the slab can nevertheless be obtained using previous work of the author and C. Pop [16]. Our Perron method relies on weak and strong maximum principles for degenerate-elliptic operators, concepts of continuous subsolutions and supersolutions for boundary value and obstacle problems for degenerate-elliptic operators, and maximum and comparison principle estimates previously developed by the author [13].

Micro-bubbles and Micro-particles are Not Faithful Tracers of Turbulent Acceleration

NASA Astrophysics Data System (ADS)

Sun, Chao; Mathai, Varghese; Calzavarini, Enrico; Brons, Jon; Lohse, Detlef

2016-11-01

We report on the Lagrangian statistics of acceleration of small (sub-Kolmogorov) bubbles and tracer particles with Stokes number St <<1 in turbulent flow. At decreasing Reynolds number, the bubble accelerations show deviations from that of tracer particles, i.e. they deviate from the Heisenberg-Yaglom prediction and show a quicker decorrelation despite their small size and minute St. Using direct numerical simulations, we show that these effects arise due the drift of these particles through the turbulent flow. We theoretically predict this gravity-driven effect for developed isotropic turbulence, with the ratio of Stokes to Froude number or equivalently the particle drift-velocity governing the enhancement of acceleration variance and the reductions in correlation time and intermittency. Our predictions are in good agreement with experimental and numerical results. The present findings are relevant to a range of scenarios encompassing tiny bubbles and droplets that drift through the turbulent oceans and the atmosphere.

Low-noise encoding of active touch by layer 4 in the somatosensory cortex.

PubMed

Hires, Samuel Andrew; Gutnisky, Diego A; Yu, Jianing; O'Connor, Daniel H; Svoboda, Karel

2015-08-06

Cortical spike trains often appear noisy, with the timing and number of spikes varying across repetitions of stimuli. Spiking variability can arise from internal (behavioral state, unreliable neurons, or chaotic dynamics in neural circuits) and external (uncontrolled behavior or sensory stimuli) sources. The amount of irreducible internal noise in spike trains, an important constraint on models of cortical networks, has been difficult to estimate, since behavior and brain state must be precisely controlled or tracked. We recorded from excitatory barrel cortex neurons in layer 4 during active behavior, where mice control tactile input through learned whisker movements. Touch was the dominant sensorimotor feature, with >70% spikes occurring in millisecond timescale epochs after touch onset. The variance of touch responses was smaller than expected from Poisson processes, often reaching the theoretical minimum. Layer 4 spike trains thus reflect the millisecond-timescale structure of tactile input with little noise.

Feeling torn when everything seems right: semantic incongruence causes felt ambivalence.

PubMed

Gebauer, Jochen E; Maio, Gregory R; Pakizeh, Ali

2013-06-01

The co-occurrence of positive and negative attributes of an attitude object typically accounts for less than a quarter of the variance in felt ambivalence toward these objects, rendering this evaluative incongruence insufficient for explaining felt ambivalence. The present research tested whether another type of incongruence, semantic incongruence, also causes felt ambivalence. Semantic incongruence arises from inconsistencies in the descriptive content of attitude objects' attributes (e.g., attributes that are not mutually supportive), independent of these attributes' valences. Experiment 1 manipulated evaluative and semantic incongruence using valence norms and semantic norms. Both of these norm-based manipulations independently predicted felt ambivalence, and, in Experiment 2, they even did so over and above self-based incongruence (i.e., participants' idiosyncratic perceptions of evaluative and semantic incongruence). Experiments 3a and 3b revealed that aversive dissonant feelings play a role in the effects of evaluative incongruence, but not semantic incongruence, on felt ambivalence.

Signal, noise, and variation in neural and sensory-motor latency

PubMed Central

Lee, Joonyeol; Joshua, Mati; Medina, Javier F.; Lisberger, Stephen G.

2016-01-01

Analysis of the neural code for sensory-motor latency in smooth pursuit eye movements reveals general principles of neural variation and the specific origin of motor latency. The trial-by-trial variation in neural latency in MT comprises: a shared component expressed as neuron-neuron latency correlations; and an independent component that is local to each neuron. The independent component arises heavily from fluctuations in the underlying probability of spiking with an unexpectedly small contribution from the stochastic nature of spiking itself. The shared component causes the latency of single neuron responses in MT to be weakly predictive of the behavioral latency of pursuit. Neural latency deeper in the motor system is more strongly predictive of behavioral latency. A model reproduces both the variance of behavioral latency and the neuron-behavior latency correlations in MT if it includes realistic neural latency variation, neuron-neuron latency correlations in MT, and noisy gain control downstream from MT. PMID:26971946

The Impact of an Aging Population in the Workplace.

PubMed

White, Mercedia Stevenson; Burns, Candace; Conlon, Helen Acree

2018-03-01

According to the Centers for Disease Control and Prevention, the number of people 65 years of age or older living in the United States is projected to double by 2030 to 72 million adults, representing 20% of the total U.S. Evidence suggests that older Americans are working longer and spending more time on the job than their peers did in previous years. The increased number of older adults working longer is observed not only in the Unites States but also worldwide. There are numerous ramifications associated with the changing demographics and the expanding prevalence of an aging population in the workforce. Dynamics that arise include stereotyping and discrimination, longevity and on-site expert knowledge, variances in workplace behavior, a multigenerational employee pool, chronic disease management, occupational safety, and the application of adaptive strategies to reduce injury occurrences. Occupational health nurses play a pivotal role in implementing best practices for an aging-friendly workplace.

Using Latent Class Analysis to Model Temperament Types.

PubMed

Loken, Eric

2004-10-01

Mixture models are appropriate for data that arise from a set of qualitatively different subpopulations. In this study, latent class analysis was applied to observational data from a laboratory assessment of infant temperament at four months of age. The EM algorithm was used to fit the models, and the Bayesian method of posterior predictive checks was used for model selection. Results show at least three types of infant temperament, with patterns consistent with those identified by previous researchers who classified the infants using a theoretically based system. Multiple imputation of group memberships is proposed as an alternative to assigning subjects to the latent class with maximum posterior probability in order to reflect variance due to uncertainty in the parameter estimation. Latent class membership at four months of age predicted longitudinal outcomes at four years of age. The example illustrates issues relevant to all mixture models, including estimation, multi-modality, model selection, and comparisons based on the latent group indicators.

Quantifying the origins of life on a planetary scale.

PubMed

Scharf, Caleb; Cronin, Leroy

2016-07-19

A simple, heuristic formula with parallels to the Drake Equation is introduced to help focus discussion on open questions for the origins of life in a planetary context. This approach indicates a number of areas where quantitative progress can be made on parameter estimation for determining origins of life probabilities, based on constraints from Bayesian approaches. We discuss a variety of "microscale" factors and their role in determining "macroscale" abiogenesis probabilities on suitable planets. We also propose that impact ejecta exchange between planets with parallel chemistries and chemical evolution could in principle amplify the development of molecular complexity and abiogenesis probabilities. This amplification could be very significant, and both bias our conclusions about abiogenesis probabilities based on the Earth and provide a major source of variance in the probability of life arising in planetary systems. We use our heuristic formula to suggest a number of observational routes for improving constraints on origins of life probabilities.

Quantifying the origins of life on a planetary scale

NASA Astrophysics Data System (ADS)

Scharf, Caleb; Cronin, Leroy

2016-07-01

A simple, heuristic formula with parallels to the Drake Equation is introduced to help focus discussion on open questions for the origins of life in a planetary context. This approach indicates a number of areas where quantitative progress can be made on parameter estimation for determining origins of life probabilities, based on constraints from Bayesian approaches. We discuss a variety of “microscale” factors and their role in determining “macroscale” abiogenesis probabilities on suitable planets. We also propose that impact ejecta exchange between planets with parallel chemistries and chemical evolution could in principle amplify the development of molecular complexity and abiogenesis probabilities. This amplification could be very significant, and both bias our conclusions about abiogenesis probabilities based on the Earth and provide a major source of variance in the probability of life arising in planetary systems. We use our heuristic formula to suggest a number of observational routes for improving constraints on origins of life probabilities.

Intermittent Fermi-Pasta-Ulam Dynamics at Equilibrium

NASA Astrophysics Data System (ADS)

Campbell, David; Danieli, Carlo; Flach, Sergej

The equilibrium value of an observable defines a manifold in the phase space of an ergodic and equipartitioned many-body syste. A typical trajectory pierces that manifold infinitely often as time goes to infinity. We use these piercings to measure both the relaxation time of the lowest frequency eigenmode of the Fermi-Pasta-Ulam chain, as well as the fluctuations of the subsequent dynamics in equilibrium. We show that previously obtained scaling laws for equipartition times are modified at low energy density due to an unexpected slowing down of the relaxation. The dynamics in equilibrium is characterized by a power-law distribution of excursion times far off equilibrium, with diverging variance. The long excursions arise from sticky dynamics close to regular orbits in the phase space. Our method is generalizable to large classes of many-body systems. The authors acknowledge financial support from IBS (Project Code IBS-R024-D1).

From direct-space discrepancy functions to crystallographic least squares.

PubMed

Giacovazzo, Carmelo

2015-01-01

Crystallographic least squares are a fundamental tool for crystal structure analysis. In this paper their properties are derived from functions estimating the degree of similarity between two electron-density maps. The new approach leads also to modifications of the standard least-squares procedures, potentially able to improve their efficiency. The role of the scaling factor between observed and model amplitudes is analysed: the concept of unlocated model is discussed and its scattering contribution is combined with that arising from the located model. Also, the possible use of an ancillary parameter, to be associated with the classical weight related to the variance of the observed amplitudes, is studied. The crystallographic discrepancy factors, basic tools often combined with least-squares procedures in phasing approaches, are analysed. The mathematical approach here described includes, as a special case, the so-called vector refinement, used when accurate estimates of the target phases are available.

Detection limits for real-time source water monitoring using indigenous freshwater microalgae

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

Rodriguez Jr, Miguel; Greenbaum, Elias

This research identified toxin detection limits using the variable fluorescence of naturally occurring microalgae in source drinking water for five chemical toxins with different molecular structures and modes of toxicity. The five chemicals investigated were atrazine, Diuron, paraquat, methyl parathion, and potassium cyanide. Absolute threshold sensitivities of the algae for detection of the toxins in unmodified source drinking water were measured. Differential kinetics between the rate of action of the toxins and natural changes in algal physiology, such as diurnal photoinhibition, are significant enough that effects of the toxin can be detected and distinguished from the natural variance. This ismore » true even for physiologically impaired algae where diminished photosynthetic capacity may arise from uncontrollable external factors such as nutrient starvation. Photoinhibition induced by high levels of solar radiation is a predictable and reversible phenomenon that can be dealt with using a period of dark adaption of 30 minutes or more.« less

Variance-based Sensitivity Analysis of Large-scale Hydrological Model to Prepare an Ensemble-based SWOT-like Data Assimilation Experiments

NASA Astrophysics Data System (ADS)

Emery, C. M.; Biancamaria, S.; Boone, A. A.; Ricci, S. M.; Garambois, P. A.; Decharme, B.; Rochoux, M. C.

2015-12-01

Land Surface Models (LSM) coupled with River Routing schemes (RRM), are used in Global Climate Models (GCM) to simulate the continental part of the water cycle. They are key component of GCM as they provide boundary conditions to atmospheric and oceanic models. However, at global scale, errors arise mainly from simplified physics, atmospheric forcing, and input parameters. More particularly, those used in RRM, such as river width, depth and friction coefficients, are difficult to calibrate and are mostly derived from geomorphologic relationships, which may not always be realistic. In situ measurements are then used to calibrate these relationships and validate the model, but global in situ data are very sparse. Additionally, due to the lack of existing global river geomorphology database and accurate forcing, models are run at coarse resolution. This is typically the case of the ISBA-TRIP model used in this study.A complementary alternative to in-situ data are satellite observations. In this regard, the Surface Water and Ocean Topography (SWOT) satellite mission, jointly developed by NASA/CNES/CSA/UKSA and scheduled for launch around 2020, should be very valuable to calibrate RRM parameters. It will provide maps of water surface elevation for rivers wider than 100 meters over continental surfaces in between 78°S and 78°N and also direct observation of river geomorphological parameters such as width ans slope.Yet, before assimilating such kind of data, it is needed to analyze RRM temporal sensitivity to time-constant parameters. This study presents such analysis over large river basins for the TRIP RRM. Model output uncertainty, represented by unconditional variance, is decomposed into ordered contribution from each parameter. Doing a time-dependent analysis allows then to identify to which parameters modeled water level and discharge are the most sensitive along a hydrological year. The results show that local parameters directly impact water levels, while discharge is more affected by parameters from the whole upstream drainage area. Understanding model output variance behavior will have a direct impact on the design and performance of the ensemble-based data assimilation platform, for which uncertainties are also modeled by variances. It will help to select more objectively RRM parameters to correct.

Structural Studies of Amorphous Materials by Fluctuation Electron Microscopy

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

Treacy, Michael M. J.

Fluctuation Electron Microscopy (FEM) is a technique that examines the fluctuations in electron scattering across a uniformly thin amorphous sample. The statistics of the intensity fluctuations, mean and variance, reveal any underlying medium-range order present in the structure. The goals of this project were: (1) To determine the fundamentals of the scattering physics that gives rise to the variance signal in fluctuation electron microscopy (FEM); (2) To use these discoveries to find ways to quantify FEM; (3) To apply the FEM method to interesting and technologically important families of amorphous materials, particularly those with important applications in energy-related processes. Excellent progress was made in items (1) and (2). In stage (3) we did not examine the metamict zircons, as proposed. Instead, we examined films of polycrystalline and amorphous semi-conducting diamond. Significant accomplishments are: (1) A Reverse Monte Carlo procedure was successfully implemented to invert FEM data into a structural model. This is computer-intensive, but it demonstrated that diffraction and FEM data from amorphous silicon are most consistent with a paracrystallite model. This means that there is more diamond-like topology present in amorphous silicon than is predicted by the continuous random network model. (2) There is significant displacement decoherence arising in diffraction from amorphous silicon and carbon. The samples are being bombarded by the electron beam and atoms do not stay still while being irradiated – much more than was formerly understood. The atom motions cause the destructive and constructive interferences in the diffraction pattern to fluctuate with time, and it is the time-averaged speckle that is being measured. The variance is reduced by a factor m, 4 ≤ m ≤ 1000, relative to that predicted by kinematical scattering theory. (3) Speckle intensity obeys a gamma distribution, where the mean intensitymore » $$ \\overline{I}\\ $$ and m are the two parameters governing the shape of the gamma distribution profile. m is determined by the illumination spatial coherence, which is normally very high, and mostly by the displacement decoherence within the sample. (4) Amorphous materials are more affected by the electron beam than are crystalline materials. Different samples exhibit different disruptibility, as measured by the effective values of m that fit the data. (5) Understanding the origin of the displacement decoherence better should lead to efficient methods for computing the observed variance from amorphous materials.« less

Small dark energy and stable vacuum from Dilaton-Gauss-Bonnet coupling in TMT

NASA Astrophysics Data System (ADS)

Guendelman, Eduardo I.; Nishino, Hitoshi; Rajpoot, Subhash

2017-04-01

In two measures theories (TMT), in addition to the Riemannian measure of integration, being the square root of the determinant of the metric, we introduce a metric-independent density Φ in four dimensions defined in terms of scalars \\varphi _a by Φ =\\varepsilon ^{μ ν ρ σ } \\varepsilon _{abcd} (partial _{μ }\\varphi _a)(partial _{ν }\\varphi _b) (partial _{ρ }\\varphi _c) (partial _{σ }\\varphi _d). With the help of a dilaton field φ we construct theories that are globally scale invariant. In particular, by introducing couplings of the dilaton φ to the Gauss-Bonnet (GB) topological density {√{-g}} φ ( R_{μ ν ρ σ }^2 - 4 R_{μ ν }^2 + R^2 ) we obtain a theory that is scale invariant up to a total divergence. Integration of the \\varphi _a field equation leads to an integration constant that breaks the global scale symmetry. We discuss the stabilizing effects of the coupling of the dilaton to the GB-topological density on the vacua with a very small cosmological constant and the resolution of the `TMT Vacuum-Manifold Problem' which exists in the zero cosmological-constant vacuum limit. This problem generically arises from an effective potential that is a perfect square, and it gives rise to a vacuum manifold instead of a unique vacuum solution in the presence of many different scalars, like the dilaton, the Higgs, etc. In the non-zero cosmological-constant case this problem disappears. Furthermore, the GB coupling to the dilaton eliminates flat directions in the effective potential, and it totally lifts the vacuum-manifold degeneracy.

Hydrodynamics of the Capture Zone of a Partially Penetrating Well in a Confined Aquifer

NASA Astrophysics Data System (ADS)

Faybishenko, Boris A.; Javandel, Iraj; Witherspoon, Paul A.

1995-04-01

In the pump and treat approach to the problem of managing a contaminated aquifer, a key problem is to design an effective capture system that collects only the polluted groundwater without allowing any of it to escape. At present, it is customary to design a capture system using fully penetrating withdrawal wells. Very often, however, only part of the vertical thickness of the aquifer is contaminated, so the question may arise whether a more efficient capture system can be achieved using partially penetrating wells. Very little work has been done on the application of partially penetrating wells to this problem. A new semianalytic method that can be used in determining the geometry of the capture zone for steady state flow to a partially penetrating well that is screened from the top (or from the bottom) of a confined aquifer has been developed. By combining the velocity potentials for flow to the well with that for the regional flow field, a three-dimensional velocity potential that can be used in determining the complete geometry of the capture surface has been developed. The results have shown that with a constant pumping rate the maximum horizontal extent of the capture surface at the top (or bottom) of the aquifer increases as the degree of penetration decreases. As one would expect, the maximum vertical extent increases as the depth of penetration increases. Thus, if one knows the actual location of the contaminant plume, an appropriate combination of the degree of penetration and pumping rate can be selected to create an effective capture zone.

Custom-Molded Foot-Orthosis Intervention and Multisegment Medial Foot Kinematics During Walking

PubMed Central

Cobb, Stephen C.; Tis, Laurie L.; Johnson, Jeffrey T.; Wang, Yong “Tai”; Geil, Mark D.

2011-01-01

Context: Foot-orthosis (FO) intervention to prevent and treat numerous lower extremity injuries is widely accepted clinically. However, the results of quantitative gait analyses have been equivocal. The foot models used, participants receiving intervention, and orthoses used might contribute to the variability. Objective: To investigate the effect of a custom-molded FO intervention on multisegment medial foot kinematics during walking in participants with low-mobile foot posture. Design: Crossover study. Setting: University biomechanics and ergonomics laboratory. Patients or Other Participants: Sixteen participants with low-mobile foot posture (7 men, 9 women) were assigned randomly to 1 of 2 FO groups. Interventions : After a 2-week period to break in the FOs, individuals participated in a gait analysis that consisted of 5 successful walking trials (1.3 to 1.4 m/s) during no-FO and FO conditions. Main Outcome Measure(s): Three-dimensional displacements during 4 subphases of stance (loading response, mid-stance, terminal stance, preswing) were computed for each multisegment foot model articulation. Results: Repeated-measures analyses of variance (ANOVAs) revealed that rearfoot complex dorsiflexion displacement during midstance was greater in the FO than the no-FO condition (F1,14 = 5.24, P = .04, partial η2 = 0.27). Terminal stance repeated-measures ANOVA results revealed insert-by-insert condition interactions for the first metatarsophalangeal joint complex (F1,14 = 7.87, P = .01, partial η2 = 0.36). However, additional follow-up analysis did not reveal differences between the no-FO and FO conditions for the balanced traditional orthosis (F1,14 = 4.32, P = .08, partial η2 = 0.38) or full-contact orthosis (F1,14 = 4.10, P = .08, partial η2 = 0.37). Conclusions: Greater rearfoot complex dorsiflexion during midstance associated with FO intervention may represent improved foot kinematics in people with low-mobile foot postures. Furthermore, FO intervention might partially correct dys-functional kinematic patterns associated with low-mobile foot postures. PMID:21944067

Flow Durations, Low-Flow Frequencies, and Monthly Median Flows for Selected Streams in Connecticut through 2005

USGS Publications Warehouse

Ahearn, Elizabeth A.

2008-01-01

Flow durations, low-flow frequencies, and monthly median streamflows were computed for 91 continuous-record, streamflow-gaging stations in Connecticut with 10 or more years of record. Flow durations include the 99-, 98-, 97-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, 50-, 40-, 30-, 25-, 20-, 10-, 5-, and 1-percent exceedances. Low-flow frequencies include the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low flow. Streamflow estimates were computed for each station using data for the period of record through water year 2005. Estimates of low-flow statistics for 7 short-term (operated between 3 and 10 years) streamflow-gaging stations and 31 partial-record sites were computed. Low-flow estimates were made on the basis of the relation between base flows at a short-term station or partial-record site and concurrent daily mean streamflows at a nearby index station. The relation is defined by the Maintenance of Variance Extension, type 3 (MOVE.3) method. Several short-term stations and partial-record sites had poorly defined relations with nearby index stations; therefore, no low-flow statistics were derived for these sites. The estimated low-flow statistics for the short-term stations and partial-record sites include the 99-, 98-, 97-, 95-, 90-, and 85-percent flow durations; the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low-flow frequencies; and the August median flow. Descriptive information on location and record length, measured basin characteristics, index stations correlated to the short-term station and partial-record sites, and estimated flow statistics are provided in this report for each station. Streamflow estimates from this study are stored on USGS's World Wide Web application 'StreamStats' (http://water.usgs.gov/osw/streamstats/connecticut.html).

Yoga Is as Good as Stretching–Strengthening Exercises in Improving Functional Fitness Outcomes: Results From a Randomized Controlled Trial

PubMed Central

McAuley, Edward

2016-01-01

Abstract Background. Despite yoga’s popularity, few clinical trials have employed rigorous methodology to systematically explore its functional benefits compared with more established forms of exercise. The objective of this study was to compare the functional benefits of yoga with the conventional stretching–strengthening exercises recommended for adults. Methods. Sedentary healthy adults ( N = 118; Mage = 62.0) participated in an 8-week (three times a week for 1 hour) randomized controlled trial, which consisted of a Hatha yoga group ( n = 61) and a stretching–strengthening exercise group ( n = 57). Standardized functional fitness tests assessing balance, strength, flexibility, and mobility were administered at baseline and postintervention. Results. A repeated measures multivariate analysis of variance showed a significant time effect for measures of balance [ F (3,18) = 4.88, p < .01, partial η 2 = .45], strength [ F (2,19) = 15.37, p < .001, partial η 2 = .62], flexibility [ F (4,17) = 8.86, p < .001, partial η 2 = .68], and mobility [ F (2,19) = 8.54, p < .002, partial η 2 = .47]. Both groups showed significant improvements on measures of balance (left–right leg and four square step); strength (chair stands and arm curls); flexibility (back scratch and sit-and-reach); and mobility (gait speed and 8-feet up and go), with partial η 2 ranging from .05 to .47. Conclusions. These data suggest that regular yoga practice is just as effective as stretching–strengthening exercises in improving functional fitness. To our knowledge, this is the first study to examine functional benefits of yoga in comparison with stretching–strengthening exercises in sedentary, healthy, community-dwelling older adults. These findings have clinical implications as yoga is a more amenable form of exercise than strengthening exercises as it requires minimal equipment and can be adapted for individuals with lower levels of functioning or disabilities. PMID:26297940

Quantification of γ-aminobutyric acid (GABA) in 1 H MRS volumes composed heterogeneously of grey and white matter.

PubMed

Mikkelsen, Mark; Singh, Krish D; Brealy, Jennifer A; Linden, David E J; Evans, C John

2016-11-01

The quantification of γ-aminobutyric acid (GABA) concentration using localised MRS suffers from partial volume effects related to differences in the intrinsic concentration of GABA in grey (GM) and white (WM) matter. These differences can be represented as a ratio between intrinsic GABA in GM and WM: r M . Individual differences in GM tissue volume can therefore potentially drive apparent concentration differences. Here, a quantification method that corrects for these effects is formulated and empirically validated. Quantification using tissue water as an internal concentration reference has been described previously. Partial volume effects attributed to r M can be accounted for by incorporating into this established method an additional multiplicative correction factor based on measured or literature values of r M weighted by the proportion of GM and WM within tissue-segmented MRS volumes. Simulations were performed to test the sensitivity of this correction using different assumptions of r M taken from previous studies. The tissue correction method was then validated by applying it to an independent dataset of in vivo GABA measurements using an empirically measured value of r M . It was shown that incorrect assumptions of r M can lead to overcorrection and inflation of GABA concentration measurements quantified in volumes composed predominantly of WM. For the independent dataset, GABA concentration was linearly related to GM tissue volume when only the water signal was corrected for partial volume effects. Performing a full correction that additionally accounts for partial volume effects ascribed to r M successfully removed this dependence. With an appropriate assumption of the ratio of intrinsic GABA concentration in GM and WM, GABA measurements can be corrected for partial volume effects, potentially leading to a reduction in between-participant variance, increased power in statistical tests and better discriminability of true effects. Copyright © 2016 John Wiley & Sons, Ltd.

Yoga Is as Good as Stretching-Strengthening Exercises in Improving Functional Fitness Outcomes: Results From a Randomized Controlled Trial.

PubMed

Gothe, Neha P; McAuley, Edward

2016-03-01

Despite yoga's popularity, few clinical trials have employed rigorous methodology to systematically explore its functional benefits compared with more established forms of exercise. The objective of this study was to compare the functional benefits of yoga with the conventional stretching-strengthening exercises recommended for adults. Sedentary healthy adults (N = 118; M age = 62.0) participated in an 8-week (three times a week for 1 hour) randomized controlled trial, which consisted of a Hatha yoga group (n = 61) and a stretching-strengthening exercise group (n = 57). Standardized functional fitness tests assessing balance, strength, flexibility, and mobility were administered at baseline and postintervention. A repeated measures multivariate analysis of variance showed a significant time effect for measures of balance [F(3,18) = 4.88, p < .01, partial η(2) = .45], strength [F(2,19) = 15.37, p < .001, partial η(2) = .62], flexibility [F(4,17) = 8.86, p < .001, partial η(2) = .68], and mobility [F(2,19) = 8.54, p < .002, partial η(2) = .47]. Both groups showed significant improvements on measures of balance (left-right leg and four square step); strength (chair stands and arm curls); flexibility (back scratch and sit-and-reach); and mobility (gait speed and 8-feet up and go), with partial η(2) ranging from .05 to .47. These data suggest that regular yoga practice is just as effective as stretching-strengthening exercises in improving functional fitness. To our knowledge, this is the first study to examine functional benefits of yoga in comparison with stretching-strengthening exercises in sedentary, healthy, community-dwelling older adults. These findings have clinical implications as yoga is a more amenable form of exercise than strengthening exercises as it requires minimal equipment and can be adapted for individuals with lower levels of functioning or disabilities. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A masking level difference due to harmonicity.

PubMed

Treurniet, W C; Boucher, D R

2001-01-01

The role of harmonicity in masking was studied by comparing the effect of harmonic and inharmonic maskers on the masked thresholds of noise probes using a three-alternative, forced-choice method. Harmonic maskers were created by selecting sets of partials from a harmonic series with an 88-Hz fundamental and 45 consecutive partials. Inharmonic maskers differed in that the partial frequencies were perturbed to nearby values that were not integer multiples of the fundamental frequency. Average simultaneous-masked thresholds were as much as 10 dB lower with the harmonic masker than with the inharmonic masker, and this difference was unaffected by masker level. It was reduced or eliminated when the harmonic partials were separated by more than 176 Hz, suggesting that the effect is related to the extent to which the harmonics are resolved by auditory filters. The threshold difference was not observed in a forward-masking experiment. Finally, an across-channel mechanism was implicated when the threshold difference was found between a harmonic masker flanked by harmonic bands and a harmonic masker flanked by inharmonic bands. A model developed to explain the observed difference recognizes that an auditory filter output envelope is modulated when the filter passes two or more sinusoids, and that the modulation rate depends on the differences among the input frequencies. For a harmonic masker, the frequency differences of adjacent partials are identical, and all auditory filters have the same dominant modulation rate. For an inharmonic masker, however, the frequency differences are not constant and the envelope modulation rate varies across filters. The model proposes that a lower variability facilitates detection of a probe-induced change in the variability, thus accounting for the masked threshold difference. The model was supported by significantly improved predictions of observed thresholds when the predictor variables included envelope modulation rate variance measured using simulated auditory filters.

Effect of a 16-week Bikram yoga program on perceived stress, self-efficacy and health-related quality of life in stressed and sedentary adults: A randomised controlled trial.

PubMed

Hewett, Zoe L; Pumpa, Kate L; Smith, Caroline A; Fahey, Paul P; Cheema, Birinder S

2018-04-01

The purpose of this study was to investigate the effect of 16 weeks of Bikram yoga on perceived stress, self-efficacy and health related quality of life (HRQoL) in sedentary, stressed adults. 16 week, parallel-arm, randomised controlled trial with flexible dosing. Physically inactive, stressed adults (37.2±10.8 years) were randomised to Bikram yoga (three to five classes per week) or control (no treatment) group for 16 weeks. Outcome measures, collected via self-report, included perceived stress, general self-efficacy, and HRQoL. Outcomes were assessed at baseline, midpoint and completion. Individuals were randomised to the experimental (n=29) or control group (n=34). Average attendance in the experimental group was 27±18 classes. Repeated measure analyses of variance (intention-to-treat) demonstrated significantly improved perceived stress (p=0.003, partial η 2 =0.109), general self-efficacy (p=0.034, partial η 2 =0.056), and the general health (p=0.034, partial η 2 =0.058) and energy/fatigue (p=0.019, partial η 2 =0.066) domains of HRQoL in the experimental group versus the control group. Attendance was significantly associated with reductions in perceived stress, and an increase in several domains of HRQoL. 16 weeks of Bikram yoga significantly improved perceived stress, general self-efficacy and HRQoL in sedentary, stressed adults. Future research should consider ways to optimise adherence, and should investigate effects of Bikram yoga intervention in other populations at risk for stress-related illness. Australia New Zealand Clinical Trials Registry ACTRN12616000867493. Registered 04 July 2016. URL: http://www.anzctr.org.au/ACTRN12616000867493.aspx. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Randomized Trial on the Effects of Attentional Focus on Motor Training of the Upper Extremity Using Robotics With Individuals After Chronic Stroke.

PubMed

Kim, Grace J; Hinojosa, Jim; Rao, Ashwini K; Batavia, Mitchell; O'Dell, Michael W

2017-10-01

To compare the long-term effects of external focus (EF) and internal focus (IF) of attention after 4 weeks of arm training. Randomized, repeated-measures, mixed analysis of variance. Outpatient clinic. Individuals with stroke and moderate-to-severe arm impairment living in the community (N=33; withdrawals: n=3). Four-week arm training protocol on a robotic device (12 sessions). Joint independence, Fugl-Meyer Assessment, and Wolf Motor Function Test measured at baseline, discharge, and 4-week follow-up. There were no between-group effects for attentional focus. Participants in both groups improved significantly on all outcome measures from baseline to discharge and maintained those changes at 4-week follow-up regardless of group assignment (joint independence EF condition: F 1.6,45.4 =17.74; P<.0005; partial η 2 =.39; joint independence IF condition: F 2,56 =18.66; P<.0005; partial η 2 =.40; Fugl-Meyer Assessment: F 2,56 =27.83; P<.0005; partial η 2 =.50; Wolf Motor Function Test: F 2,56 =14.05; P<.0005; partial η 2 =.35). There were no differences in retention of motor skills between EF and IF participants 4 weeks after arm training, suggesting that individuals with moderate-to-severe arm impairment may not experience the advantages of an EF found in healthy individuals. Attentional focus is most likely not an active ingredient for retention of trained motor skills for individuals with moderate-to-severe arm impairment, whereas dosage and intensity of practice appear to be pivotal. Future studies should investigate the long-term effects of attentional focus for individuals with mild arm impairment. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Short-term intravenous citalopram augmentation in partial/nonresponders with major depression: a randomized placebo-controlled study.

PubMed

Altamura, Alfredo Carlo; Dell'Osso, Bernardo; Buoli, Massimiliano; Bosi, Monica; Mundo, Emanuela

2008-07-01

Approximately 30-45% of patients with major depressive episode (MDE) do not fully respond to standard recommended treatments and further strategies of intervention, including pharmacological augmentation, have been proposed for these patients. This study was aimed to evaluate the efficacy of short-term, low-dose (10 mg/day) intravenous (i.v.) citalopram augmentation versus placebo in a sample of patients with MDE and partial or no response to selective serotonin reuptake inhibitors (SSRIs). Thirty-six patients with a Diagnostic and Statistical Manual for Mental Disorders, 4th edition, text revision criteria MDE and partial or no response to oral SSRIs were selected and randomly assigned to citalopram (n=18) or to placebo (n=18) i.v. augmentation. The augmentation regimen lasted 5 consecutive days during which the patients were maintained on their current treatment with oral SSRIs. Analyses of variance with repeated measures on Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale total scores, administered daily with blind-raters conditions, were done. With regard to the Hamilton Depression Rating Scale total scores, a significant time effect (F=42.02, P<0.0001) and timextreatment effect (F=21.17, P<0.0001) were found in favor of citalopram. Similar results were obtained from the analysis on Montgomery-Asberg Depression Rating Scale total scores: time effect (F=50.07, P<0.0001), timextreatment effect (F=19.91, P<0.0001), and treatment effect (F=4.07, P=0.05). Even though referred to a small sample, the present findings seem to suggest that short-term, low-dose, i.v. citalopram augmentation may be effective in depressed patients with partial or no response to oral SSRIs. Further controlled studies performed with double-blind conditions are warranted to confirm the present results.

"A Vegetarian vs. Conventional Hypocaloric Diet: The Effect on Physical Fitness in Response to Aerobic Exercise in Patients with Type 2 Diabetes." A Parallel Randomized Study.

PubMed

Veleba, Jiri; Matoulek, Martin; Hill, Martin; Pelikanova, Terezie; Kahleova, Hana

2016-10-26

It has been shown that it is possible to modify macronutrient oxidation, physical fitness and resting energy expenditure (REE) by changes in diet composition. Furthermore, mitochondrial oxidation can be significantly increased by a diet with a low glycemic index. The purpose of our trial was to compare the effects of a vegetarian (V) and conventional diet (C) with the same caloric restriction (-500 kcal/day) on physical fitness and REE after 12 weeks of diet plus aerobic exercise in 74 patients with type 2 diabetes (T2D). An open, parallel, randomized study design was used. All meals were provided for the whole study duration. An individualized exercise program was prescribed to the participants and was conducted under supervision. Physical fitness was measured by spiroergometry and indirect calorimetry was performed at the start and after 12 weeks Repeated-measures ANOVA (Analysis of variance) models with between-subject (group) and within-subject (time) factors and interactions were used for evaluation of the relationships between continuous variables and factors. Maximal oxygen consumption (VO 2max ) increased by 12% in vegetarian group (V) (F = 13.1, p < 0.001, partial η ² = 0.171), whereas no significant change was observed in C (F = 0.7, p = 0.667; group × time F = 9.3, p = 0.004, partial η ² = 0.209). Maximal performance (Watt max) increased by 21% in V (F = 8.3, p < 0.001, partial η ² = 0.192), whereas it did not change in C (F = 1.0, p = 0.334; group × time F = 4.2, p = 0.048, partial η ² = 0.116). Our results indicate that V leads more effectively to improvement in physical fitness than C after aerobic exercise program.

Low back pain in a child associated with acute onset cauda equina syndrome: a rare presentation of an aggressive vertebral hemangioma: a case report.

PubMed

Pretell-Mazzini, Juan; Chikwava, Kudakwashe R; Dormans, John Paul

2012-01-01

Back pain prevalence in the pediatric age group is less compared with adults. There is a wide range of possible etiologies, and tumors such as primary spinal hemangiomas are uncommon. Most are incidental findings and asymptomatic; however, painful lesions can be presented in up to 0.9% to 1.2% of cases. These lesions can produce neurologic involvement either spinal cord compression or cauda equina syndrome as in our case. The aim of this study is to describe a case of low back pain in a child due to a vertebral hemangioma complicated with acute cauda equina syndrome, and performed a literature review that will help us to recognize this aggressive variance making an early treatment feasible. A 13-year-old female, follow-up in an outer health care center due to a L1 vertebral hemangioma, characterized by 3 years of low back pain without neurologic symptoms presented to our emergency department with an acute cauda equina syndrome. An outside magnetic resonance imaging showed complete obliteration of the spinal canal at the level of the conus medullaris related to retropulsion of bone at L1. She underwent 2-stage surgical treatment: complete posterior L1 laminectomy and partial T12-L2 laminectomies, with partial L1 vertebrectomy and posterior fusion with instrumention from T11 to L3. Three weeks later, embolization before anterior fusion with inner body cage was performed. Forty months after surgery, she is doing well with no neurologic deficits. Even though hemangiomas are not a common cause of back pain, they should be taken into account. It is important to recognize the aggressive variance so an early treatment could be performed. There is no enough clinical data to establish guidelines of management in children, therefore, the treatment should be individualized.

Genetic background in partitioning of metabolizable energy efficiency in dairy cows.

PubMed

Mehtiö, T; Negussie, E; Mäntysaari, P; Mäntysaari, E A; Lidauer, M H

2018-05-01

The main objective of this study was to assess the genetic differences in metabolizable energy efficiency and efficiency in partitioning metabolizable energy in different pathways: maintenance, milk production, and growth in primiparous dairy cows. Repeatability models for residual energy intake (REI) and metabolizable energy intake (MEI) were compared and the genetic and permanent environmental variations in MEI were partitioned into its energy sinks using random regression models. We proposed 2 new feed efficiency traits: metabolizable energy efficiency (MEE), which is formed by modeling MEI fitting regressions on energy sinks [metabolic body weight (BW 0.75 ), energy-corrected milk, body weight gain, and body weight loss] directly; and partial MEE (pMEE), where the model for MEE is extended with regressions on energy sinks nested within additive genetic and permanent environmental effects. The data used were collected from Luke's experimental farms Rehtijärvi and Minkiö between 1998 and 2014. There were altogether 12,350 weekly MEI records on 495 primiparous Nordic Red dairy cows from wk 2 to 40 of lactation. Heritability estimates for REI and MEE were moderate, 0.33 and 0.26, respectively. The estimate of the residual variance was smaller for MEE than for REI, indicating that analyzing weekly MEI observations simultaneously with energy sinks is preferable. Model validation based on Akaike's information criterion showed that pMEE models fitted the data even better and also resulted in smaller residual variance estimates. However, models that included random regression on BW 0.75 converged slowly. The resulting genetic standard deviation estimate from the pMEE coefficient for milk production was 0.75 MJ of MEI/kg of energy-corrected milk. The derived partial heritabilities for energy efficiency in maintenance, milk production, and growth were 0.02, 0.06, and 0.04, respectively, indicating that some genetic variation may exist in the efficiency of using metabolizable energy for different pathways in dairy cows. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effects of radiative heat transfer on the turbulence structure in inert and reacting mixing layers

NASA Astrophysics Data System (ADS)

Ghosh, Somnath; Friedrich, Rainer

2015-05-01

We use large-eddy simulation to study the interaction between turbulence and radiative heat transfer in low-speed inert and reacting plane temporal mixing layers. An explicit filtering scheme based on approximate deconvolution is applied to treat the closure problem arising from quadratic nonlinearities of the filtered transport equations. In the reacting case, the working fluid is a mixture of ideal gases where the low-speed stream consists of hydrogen and nitrogen and the high-speed stream consists of oxygen and nitrogen. Both streams are premixed in a way that the free-stream densities are the same and the stoichiometric mixture fraction is 0.3. The filtered heat release term is modelled using equilibrium chemistry. In the inert case, the low-speed stream consists of nitrogen at a temperature of 1000 K and the highspeed stream is pure water vapour of 2000 K, when radiation is turned off. Simulations assuming the gas mixtures as gray gases with artificially increased Planck mean absorption coefficients are performed in which the large-eddy simulation code and the radiation code PRISSMA are fully coupled. In both cases, radiative heat transfer is found to clearly affect fluctuations of thermodynamic variables, Reynolds stresses, and Reynolds stress budget terms like pressure-strain correlations. Source terms in the transport equation for the variance of temperature are used to explain the decrease of this variance in the reacting case and its increase in the inert case.

Predictable and unpredictable modes of seasonal mean precipitation over Northeast China

NASA Astrophysics Data System (ADS)

Ying, Kairan; Frederiksen, Carsten S.; Zhao, Tianbao; Zheng, Xiaogu; Xiong, Zhe; Yi, Xue; Li, Chunxiang

2018-04-01

This study investigates the patterns of interannual variability that arise from the potentially predictable (slow) and unpredictable (intraseasonal) components of seasonal mean precipitation over Northeast (NE) China, using observations from a network of 162 meteorological stations for the period 1961-2014. A variance decomposition method is applied to identify the sources of predictability, as well as the sources of prediction uncertainty, for January-February-March (JFM), April-May-June (AMJ), July-August-September (JAS) and October-November-December (OND). The averaged potential predictability (ratio of slow to total variance) of NE China precipitation has the highest value of 0.32 during JAS and lowest value of 0.1 in AMJ. Possible sources of seasonal prediction for the leading predictable precipitation EOF modes come from the SST anomalies in the Japan Sea, as well as the North Atlantic during JFM, the Indian Ocean SST in AMJ, and the eastern tropical Pacific SST in JAS and OND. The prolonged linear trend, which is seen in the principal component time series of the leading predictable mode in JFM and OND, may also serve as a source of predictability. The Polar-Eurasia and Northern Annular Mode atmospheric teleconnection patterns are closely connected with the leading and the second predictable mode of JAS, respectively. The Hadley cell circulation is closely related to the leading predictable mode of OND. The leading/second unpredictable precipitation modes for all these four seasons show a similar monopole/dipole structure, and can be largely attributed to the intraseasonal variabilities of the atmosphere.

Ensemble modeling of stochastic unsteady open-channel flow in terms of its time-space evolutionary probability distribution - Part 2: numerical application

NASA Astrophysics Data System (ADS)

Dib, Alain; Kavvas, M. Levent

2018-03-01

The characteristic form of the Saint-Venant equations is solved in a stochastic setting by using a newly proposed Fokker-Planck Equation (FPE) methodology. This methodology computes the ensemble behavior and variability of the unsteady flow in open channels by directly solving for the flow variables' time-space evolutionary probability distribution. The new methodology is tested on a stochastic unsteady open-channel flow problem, with an uncertainty arising from the channel's roughness coefficient. The computed statistical descriptions of the flow variables are compared to the results obtained through Monte Carlo (MC) simulations in order to evaluate the performance of the FPE methodology. The comparisons show that the proposed methodology can adequately predict the results of the considered stochastic flow problem, including the ensemble averages, variances, and probability density functions in time and space. Unlike the large number of simulations performed by the MC approach, only one simulation is required by the FPE methodology. Moreover, the total computational time of the FPE methodology is smaller than that of the MC approach, which could prove to be a particularly crucial advantage in systems with a large number of uncertain parameters. As such, the results obtained in this study indicate that the proposed FPE methodology is a powerful and time-efficient approach for predicting the ensemble average and variance behavior, in both space and time, for an open-channel flow process under an uncertain roughness coefficient.

Catchment heterogeneity controls emergent archetype concentration-discharge relationships

NASA Astrophysics Data System (ADS)

Musolff, A.; Fleckenstein, J. H.; Rao, P. S.; Jawitz, J. W.

2017-12-01

Relationships between in-stream dissolved solute concentrations (C) and discharge (Q) are often-used indicators of catchment-scale processes and their interference with human activities. Here we analyze observational C-Q relationships from 61 catchments and 8 different solutes across a wide range of land-uses and discharge regimes. This analysis is combined with a parsimonious stochastic modeling approach to test how C-Q relationships arise from spatial heterogeneity in catchment solute sources coupled with different timescales of biogeochemical reactions. The observational data exhibit archetypical dilution, enrichment, and constant C-Q patterns. Moreover, with land-use intensification we find decreasing C variability relative to Q variability (chemostatic export regime). Our model indicates that the dominant driver of emergent C-Q patterns was structured heterogeneity of solute sources implemented as correlation of source concentration to travel time. Regardless of the C-Q pattern, with decreasing source heterogeneity we consistently find lower variability in C than in Q and a dominance of chemostatic export regimes. Here, the variance in exported loads is determined primarily by variance of Q. We conclude that efforts to improve stream water quality and ecological integrity in intensely managed catchments should lead away from landscape homogenization by introducing structured source heterogeneity. References: Musolff, A., J. H. Fleckenstein, P. S. C. Rao, and J. W. Jawitz (2017), Emergent archetype patterns of coupled hydrologic and biogeochemical responses in catchments, Geophys. Res. Lett., 44(9), 4143-4151, doi: 10.1002/2017GL072630.

Floral trait variation and integration as a function of sexual deception in Gorteria diffusa.

PubMed

Ellis, Allan G; Brockington, Samuel F; de Jager, Marinus L; Mellers, Gregory; Walker, Rachel H; Glover, Beverley J

2014-08-19

Phenotypic integration, the coordinated covariance of suites of morphological traits, is critical for proper functioning of organisms. Angiosperm flowers are complex structures comprising suites of traits that function together to achieve effective pollen transfer. Floral integration could reflect shared genetic and developmental control of these traits, or could arise through pollinator-imposed stabilizing correlational selection on traits. We sought to expose mechanisms underlying floral trait integration in the sexually deceptive daisy, Gorteria diffusa, by testing the hypothesis that stabilizing selection imposed by male pollinators on floral traits involved in mimicry has resulted in tighter integration. To do this, we quantified patterns of floral trait variance and covariance in morphologically divergent G. diffusa floral forms representing a continuum in the levels of sexual deception. We show that integration of traits functioning in visual attraction of male pollinators increases with pollinator deception, and is stronger than integration of non-mimicry trait modules. Consistent patterns of within-population trait variance and covariance across floral forms suggest that integration has not been built by stabilizing correlational selection on genetically independent traits. Instead pollinator specialization has selected for tightened integration within modules of linked traits. Despite potentially strong constraint on morphological evolution imposed by developmental genetic linkages between traits, we demonstrate substantial divergence in traits across G. diffusa floral forms and show that divergence has often occurred without altering within-population patterns of trait correlations. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Multichannel Singular Spectrum Analysis in the Estimates of Common Environmental Effects Affecting GPS Observations

NASA Astrophysics Data System (ADS)

Gruszczynska, Marta; Rosat, Severine; Klos, Anna; Gruszczynski, Maciej; Bogusz, Janusz

2018-03-01

We described a spatio-temporal analysis of environmental loading models: atmospheric, continental hydrology, and non-tidal ocean changes, based on multichannel singular spectrum analysis (MSSA). We extracted the common annual signal for 16 different sections related to climate zones: equatorial, arid, warm, snow, polar and continents. We used the loading models estimated for a set of 229 ITRF2014 (International Terrestrial Reference Frame) International GNSS Service (IGS) stations and discussed the amount of variance explained by individual modes, proving that the common annual signal accounts for 16, 24 and 68% of the total variance of non-tidal ocean, atmospheric and hydrological loading models, respectively. Having removed the common environmental MSSA seasonal curve from the corresponding GPS position time series, we found that the residual station-specific annual curve modelled with the least-squares estimation has the amplitude of maximum 2 mm. This means that the environmental loading models underestimate the seasonalities observed by the GPS system. The remaining signal present in the seasonal frequency band arises from the systematic errors which are not of common environmental or geophysical origin. Using common mode error (CME) estimates, we showed that the direct removal of environmental loading models from the GPS series causes an artificial loss in the CME power spectra between 10 and 80 cycles per year. When environmental effect is removed from GPS series with MSSA curves, no influence on the character of spectra of CME estimates was noticed.

Effects of radiative heat transfer on the turbulence structure in inert and reacting mixing layers

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

Ghosh, Somnath, E-mail: sghosh@aero.iitkgp.ernet.in; Friedrich, Rainer

2015-05-15

We use large-eddy simulation to study the interaction between turbulence and radiative heat transfer in low-speed inert and reacting plane temporal mixing layers. An explicit filtering scheme based on approximate deconvolution is applied to treat the closure problem arising from quadratic nonlinearities of the filtered transport equations. In the reacting case, the working fluid is a mixture of ideal gases where the low-speed stream consists of hydrogen and nitrogen and the high-speed stream consists of oxygen and nitrogen. Both streams are premixed in a way that the free-stream densities are the same and the stoichiometric mixture fraction is 0.3. Themore » filtered heat release term is modelled using equilibrium chemistry. In the inert case, the low-speed stream consists of nitrogen at a temperature of 1000 K and the highspeed stream is pure water vapour of 2000 K, when radiation is turned off. Simulations assuming the gas mixtures as gray gases with artificially increased Planck mean absorption coefficients are performed in which the large-eddy simulation code and the radiation code PRISSMA are fully coupled. In both cases, radiative heat transfer is found to clearly affect fluctuations of thermodynamic variables, Reynolds stresses, and Reynolds stress budget terms like pressure-strain correlations. Source terms in the transport equation for the variance of temperature are used to explain the decrease of this variance in the reacting case and its increase in the inert case.« less

Classification of biosensor time series using dynamic time warping: applications in screening cancer cells with characteristic biomarkers.

PubMed

Rai, Shesh N; Trainor, Patrick J; Khosravi, Farhad; Kloecker, Goetz; Panchapakesan, Balaji

2016-01-01

The development of biosensors that produce time series data will facilitate improvements in biomedical diagnostics and in personalized medicine. The time series produced by these devices often contains characteristic features arising from biochemical interactions between the sample and the sensor. To use such characteristic features for determining sample class, similarity-based classifiers can be utilized. However, the construction of such classifiers is complicated by the variability in the time domains of such series that renders the traditional distance metrics such as Euclidean distance ineffective in distinguishing between biological variance and time domain variance. The dynamic time warping (DTW) algorithm is a sequence alignment algorithm that can be used to align two or more series to facilitate quantifying similarity. In this article, we evaluated the performance of DTW distance-based similarity classifiers for classifying time series that mimics electrical signals produced by nanotube biosensors. Simulation studies demonstrated the positive performance of such classifiers in discriminating between time series containing characteristic features that are obscured by noise in the intensity and time domains. We then applied a DTW distance-based k -nearest neighbors classifier to distinguish the presence/absence of mesenchymal biomarker in cancer cells in buffy coats in a blinded test. Using a train-test approach, we find that the classifier had high sensitivity (90.9%) and specificity (81.8%) in differentiating between EpCAM-positive MCF7 cells spiked in buffy coats and those in plain buffy coats.

Multichannel Singular Spectrum Analysis in the Estimates of Common Environmental Effects Affecting GPS Observations

NASA Astrophysics Data System (ADS)

Gruszczynska, Marta; Rosat, Severine; Klos, Anna; Gruszczynski, Maciej; Bogusz, Janusz

2018-05-01

We described a spatio-temporal analysis of environmental loading models: atmospheric, continental hydrology, and non-tidal ocean changes, based on multichannel singular spectrum analysis (MSSA). We extracted the common annual signal for 16 different sections related to climate zones: equatorial, arid, warm, snow, polar and continents. We used the loading models estimated for a set of 229 ITRF2014 (International Terrestrial Reference Frame) International GNSS Service (IGS) stations and discussed the amount of variance explained by individual modes, proving that the common annual signal accounts for 16, 24 and 68% of the total variance of non-tidal ocean, atmospheric and hydrological loading models, respectively. Having removed the common environmental MSSA seasonal curve from the corresponding GPS position time series, we found that the residual station-specific annual curve modelled with the least-squares estimation has the amplitude of maximum 2 mm. This means that the environmental loading models underestimate the seasonalities observed by the GPS system. The remaining signal present in the seasonal frequency band arises from the systematic errors which are not of common environmental or geophysical origin. Using common mode error (CME) estimates, we showed that the direct removal of environmental loading models from the GPS series causes an artificial loss in the CME power spectra between 10 and 80 cycles per year. When environmental effect is removed from GPS series with MSSA curves, no influence on the character of spectra of CME estimates was noticed.

Least-squares dual characterization for ROI assessment in emission tomography

NASA Astrophysics Data System (ADS)

Ben Bouallègue, F.; Crouzet, J. F.; Dubois, A.; Buvat, I.; Mariano-Goulart, D.

2013-06-01

Our aim is to describe an original method for estimating the statistical properties of regions of interest (ROIs) in emission tomography. Drawn upon the works of Louis on the approximate inverse, we propose a dual formulation of the ROI estimation problem to derive the ROI activity and variance directly from the measured data without any image reconstruction. The method requires the definition of an ROI characteristic function that can be extracted from a co-registered morphological image. This characteristic function can be smoothed to optimize the resolution-variance tradeoff. An iterative procedure is detailed for the solution of the dual problem in the least-squares sense (least-squares dual (LSD) characterization), and a linear extrapolation scheme is described to compensate for sampling partial volume effect and reduce the estimation bias (LSD-ex). LSD and LSD-ex are compared with classical ROI estimation using pixel summation after image reconstruction and with Huesman's method. For this comparison, we used Monte Carlo simulations (GATE simulation tool) of 2D PET data of a Hoffman brain phantom containing three small uniform high-contrast ROIs and a large non-uniform low-contrast ROI. Our results show that the performances of LSD characterization are at least as good as those of the classical methods in terms of root mean square (RMS) error. For the three small tumor regions, LSD-ex allows a reduction in the estimation bias by up to 14%, resulting in a reduction in the RMS error of up to 8.5%, compared with the optimal classical estimation. For the large non-specific region, LSD using appropriate smoothing could intuitively and efficiently handle the resolution-variance tradeoff.

Field-based insights to the evolution of specialization: plasticity and fitness across habitats in a specialist/generalist species pair.

PubMed

Griffith, Timothy; Sultan, Sonia E

2012-04-01

Factors promoting the evolution of specialists versus generalists have been little studied in ecological context. In a large-scale comparative field experiment, we studied genotypes from naturally evolved populations of a closely related generalist/specialist species pair (Polygonum persicaria and P. hydropiper), reciprocally transplanting replicates of multiple lines into open and partially shaded sites where the species naturally co-occur. We measured relative fitness, individual plasticity, herbivory, and genetic variance expressed in the contrasting light habitats at both low and high densities. Fitness data confirmed that the putative specialist out-performed the generalist in only one environment, the favorable full sun/low-density environment to which it is largely restricted in nature, while the generalist had higher lifetime reproduction in both canopy and dense neighbor shade. The generalist, P. persicaria, also expressed greater adaptive plasticity for biomass allocation and leaf size in shaded conditions than the specialist. We found no evidence that the ecological specialization of P. hydropiper reflects either genetically based fitness trade-offs or maintenance costs of plasticity, two types of genetic constraint often invoked to prevent the evolution of broadly adaptive genotypes. However, the patterns of fitness variance and herbivore damage revealed how release from herbivory in a new range can cause an introduced species to evolve as a specialist in that range, a surprising finding with important implications for invasion biology. Patterns of fitness variance between and within sites are also consistent with a possible role for the process of mutation accumulation (in this case, mutations affecting shade-expressed phenotypes) in the evolution and/or maintenance of specialization in P. hydropiper.

Field-based insights to the evolution of specialization: plasticity and fitness across habitats in a specialist/generalist species pair

PubMed Central

Griffith, Timothy; Sultan, Sonia E

2012-01-01

Factors promoting the evolution of specialists versus generalists have been little studied in ecological context. In a large-scale comparative field experiment, we studied genotypes from naturally evolved populations of a closely related generalist/specialist species pair (Polygonum persicaria and P. hydropiper), reciprocally transplanting replicates of multiple lines into open and partially shaded sites where the species naturally co-occur. We measured relative fitness, individual plasticity, herbivory, and genetic variance expressed in the contrasting light habitats at both low and high densities. Fitness data confirmed that the putative specialist out-performed the generalist in only one environment, the favorable full sun/low-density environment to which it is largely restricted in nature, while the generalist had higher lifetime reproduction in both canopy and dense neighbor shade. The generalist, P. persicaria, also expressed greater adaptive plasticity for biomass allocation and leaf size in shaded conditions than the specialist. We found no evidence that the ecological specialization of P. hydropiper reflects either genetically based fitness trade-offs or maintenance costs of plasticity, two types of genetic constraint often invoked to prevent the evolution of broadly adaptive genotypes. However, the patterns of fitness variance and herbivore damage revealed how release from herbivory in a new range can cause an introduced species to evolve as a specialist in that range, a surprising finding with important implications for invasion biology. Patterns of fitness variance between and within sites are also consistent with a possible role for the process of mutation accumulation (in this case, mutations affecting shade-expressed phenotypes) in the evolution and/or maintenance of specialization in P. hydropiper. PMID:22837826

Discerning some Tylenol brands using attenuated total reflection Fourier transform infrared data and multivariate analysis techniques.

PubMed

Msimanga, Huggins Z; Ollis, Robert J

2010-06-01

Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to classify acetaminophen-containing medicines using their attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectra. Four formulations of Tylenol (Arthritis Pain Relief, Extra Strength Pain Relief, 8 Hour Pain Relief, and Extra Strength Pain Relief Rapid Release) along with 98% pure acetaminophen were selected for this study because of the similarity of their spectral features, with correlation coefficients ranging from 0.9857 to 0.9988. Before acquiring spectra for the predictor matrix, the effects on spectral precision with respect to sample particle size (determined by sieve size opening), force gauge of the ATR accessory, sample reloading, and between-tablet variation were examined. Spectra were baseline corrected and normalized to unity before multivariate analysis. Analysis of variance (ANOVA) was used to study spectral precision. The large particles (35 mesh) showed large variance between spectra, while fine particles (120 mesh) indicated good spectral precision based on the F-test. Force gauge setting did not significantly affect precision. Sample reloading using the fine particle size and a constant force gauge setting of 50 units also did not compromise precision. Based on these observations, data acquisition for the predictor matrix was carried out with the fine particles (sieve size opening of 120 mesh) at a constant force gauge setting of 50 units. After removing outliers, PCA successfully classified the five samples in the first and second components, accounting for 45.0% and 24.5% of the variances, respectively. The four-component PLS-DA model (R(2)=0.925 and Q(2)=0.906) gave good test spectra predictions with an overall average of 0.961 +/- 7.1% RSD versus the expected 1.0 prediction for the 20 test spectra used.

How strongly do word reading times and lexical decision times correlate? Combining data from eye movement corpora and megastudies.

PubMed

Kuperman, Victor; Drieghe, Denis; Keuleers, Emmanuel; Brysbaert, Marc

2013-01-01

We assess the amount of shared variance between three measures of visual word recognition latencies: eye movement latencies, lexical decision times, and naming times. After partialling out the effects of word frequency and word length, two well-documented predictors of word recognition latencies, we see that 7-44% of the variance is uniquely shared between lexical decision times and naming times, depending on the frequency range of the words used. A similar analysis of eye movement latencies shows that the percentage of variance they uniquely share either with lexical decision times or with naming times is much lower. It is 5-17% for gaze durations and lexical decision times in studies with target words presented in neutral sentences, but drops to 0.2% for corpus studies in which eye movements to all words are analysed. Correlations between gaze durations and naming latencies are lower still. These findings suggest that processing times in isolated word processing and continuous text reading are affected by specific task demands and presentation format, and that lexical decision times and naming times are not very informative in predicting eye movement latencies in text reading once the effect of word frequency and word length are taken into account. The difference between controlled experiments and natural reading suggests that reading strategies and stimulus materials may determine the degree to which the immediacy-of-processing assumption and the eye-mind assumption apply. Fixation times are more likely to exclusively reflect the lexical processing of the currently fixated word in controlled studies with unpredictable target words rather than in natural reading of sentences or texts.

Three-dimensional semi-analytical solution to groundwater flow in confined and unconfined wedge-shaped aquifers

NASA Astrophysics Data System (ADS)

Sedghi, Mohammad Mahdi; Samani, Nozar; Sleep, Brent

2009-06-01

The Laplace domain solutions have been obtained for three-dimensional groundwater flow to a well in confined and unconfined wedge-shaped aquifers. The solutions take into account partial penetration effects, instantaneous drainage or delayed yield, vertical anisotropy and the water table boundary condition. As a basis, the Laplace domain solutions for drawdown created by a point source in uniform, anisotropic confined and unconfined wedge-shaped aquifers are first derived. Then, by the principle of superposition the point source solutions are extended to the cases of partially and fully penetrating wells. Unlike the previous solution for the confined aquifer that contains improper integrals arising from the Hankel transform [Yeh HD, Chang YC. New analytical solutions for groundwater flow in wedge-shaped aquifers with various topographic boundary conditions. Adv Water Resour 2006;26:471-80], numerical evaluation of our solution is relatively easy using well known numerical Laplace inversion methods. The effects of wedge angle, pumping well location and observation point location on drawdown and the effects of partial penetration, screen location and delay index on the wedge boundary hydraulic gradient in unconfined aquifers have also been investigated. The results are presented in the form of dimensionless drawdown-time and boundary gradient-time type curves. The curves are useful for parameter identification, calculation of stream depletion rates and the assessment of water budgets in river basins.