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Sample records for additional dependent variable

  1. Independent, dependent, and other variables in healthcare and chaplaincy research.

    PubMed

    Flannelly, Laura T; Flannelly, Kevin J; Jankowski, Katherine R B

    2014-01-01

    This article begins by defining the term variable and the terms independent variable and dependent variable, providing examples of each. It then proceeds to describe and discuss synonyms for the terms independent variable and dependent variable, including treatment, intervention, predictor, and risk factor, and synonyms for dependent variable, such as response variables and outcomes. The article explains that the terms extraneous, nuisance, and confounding variables refer to any variable that can interfere with the ability to establish relationships between independent variables and dependent variables, and it describes ways to control for such confounds. It further explains that even though intervening, mediating, and moderating variables explicitly alter the relationship between independent variables and dependent variables, they help to explain the causal relationship between them. In addition, the article links terminology about variables with the concept of levels of measurement in research.

  2. Reward-Dependent Modulation of Movement Variability

    PubMed Central

    Izawa, Jun; Shadmehr, Reza

    2015-01-01

    Movement variability is often considered an unwanted byproduct of a noisy nervous system. However, variability can signal a form of implicit exploration, indicating that the nervous system is intentionally varying the motor commands in search of actions that yield the greatest success. Here, we investigated the role of the human basal ganglia in controlling reward-dependent motor variability as measured by trial-to-trial changes in performance during a reaching task. We designed an experiment in which the only performance feedback was success or failure and quantified how reach variability was modulated as a function of the probability of reward. In healthy controls, reach variability increased as the probability of reward decreased. Control of variability depended on the history of past rewards, with the largest trial-to-trial changes occurring immediately after an unrewarded trial. In contrast, in participants with Parkinson's disease, a known example of basal ganglia dysfunction, reward was a poor modulator of variability; that is, the patients showed an impaired ability to increase variability in response to decreases in the probability of reward. This was despite the fact that, after rewarded trials, reach variability in the patients was comparable to healthy controls. In summary, we found that movement variability is partially a form of exploration driven by the recent history of rewards. When the function of the human basal ganglia is compromised, the reward-dependent control of movement variability is impaired, particularly affecting the ability to increase variability after unsuccessful outcomes. PMID:25740529

  3. Additional security features for optically variable foils

    NASA Astrophysics Data System (ADS)

    Marshall, Allan C.; Russo, Frank

    1998-04-01

    For thousands of years, man has exploited the attraction and radiance of pure gold to adorn articles of great significance. Today, designers decorate packaging with metallic gold foils to maintain the prestige of luxury items such as perfumes, chocolates, wine and whisky, and to add visible appeal and value to wide range of products. However, today's products do not call for the hand beaten gold leaf of the Ancient Egyptians, instead a rapid production technology exists which makes use of accurately coated thin polymer films and vacuum deposited metallic layers. Stamping Foils Technology is highly versatile since several different layers may be combined into one product, each providing a different function. Not only can a foil bring visual appeal to an article, it can provide physical and chemical resistance properties and also protect an article from human forms of interference, such as counterfeiting, copying or tampering. Stamping foils have proved to be a highly effective vehicle for applying optical devices to items requiring this type of protection. Credit cards, bank notes, personal identification documents and more recently high value packaged items such as software and perfumes are protected by optically variable devices applied using stamping foil technology.

  4. Problems Identifying Independent and Dependent Variables

    ERIC Educational Resources Information Center

    Leatham, Keith R.

    2012-01-01

    This paper discusses one step from the scientific method--that of identifying independent and dependent variables--from both scientific and mathematical perspectives. It begins by analyzing an episode from a middle school mathematics classroom that illustrates the need for students and teachers alike to develop a robust understanding of…

  5. Choice of Variables and Preconditioning for Time Dependent Problems

    NASA Technical Reports Server (NTRS)

    Turkel, Eli; Vatsa, Verr N.

    2003-01-01

    We consider the use of low speed preconditioning for time dependent problems. These are solved using a dual time step approach. We consider the effect of this dual time step on the parameter of the low speed preconditioning. In addition, we compare the use of two sets of variables, conservation and primitive variables, to solve the system. We show the effect of these choices on both the convergence to a steady state and the accuracy of the numerical solutions for low Mach number steady state and time dependent flows.

  6. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ....650 Rate for additional dependent. (a) Running awards. Except as provided in paragraph (c) of this...: (1) Where benefits would be payable from a date prior to the date of filing claim, the reduction will be effective from the date of potential entitlement of the additional dependent. (2) Where...

  7. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ....650 Rate for additional dependent. (a) Running awards. Except as provided in paragraph (c) of this...: (1) Where benefits would be payable from a date prior to the date of filing claim, the reduction will be effective from the date of potential entitlement of the additional dependent. (2) Where...

  8. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ....650 Rate for additional dependent. (a) Running awards. Except as provided in paragraph (c) of this...: (1) Where benefits would be payable from a date prior to the date of filing claim, the reduction will be effective from the date of potential entitlement of the additional dependent. (2) Where...

  9. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ....650 Rate for additional dependent. (a) Running awards. Except as provided in paragraph (c) of this...: (1) Where benefits would be payable from a date prior to the date of filing claim, the reduction will be effective from the date of potential entitlement of the additional dependent. (2) Where...

  10. Decreasing Cloudiness Over China: An Updated Analysis Examining Additional Variables

    SciTech Connect

    Kaiser, D.P.

    2000-01-14

    As preparation of the IPCC's Third Assessment Report takes place, one of the many observed climate variables of key interest is cloud amount. For several nations of the world, there exist records of surface-observed cloud amount dating back to the middle of the 20th Century or earlier, offering valuable information on variations and trends. Studies using such databases include Sun and Groisman (1999) and Kaiser and Razuvaev (1995) for the former Soviet Union, Angel1 et al. (1984) for the United States, Henderson-Sellers (1986) for Europe, Jones and Henderson-Sellers (1992) for Australia, and Kaiser (1998) for China. The findings of Kaiser (1998) differ from the other studies in that much of China appears to have experienced decreased cloudiness over recent decades (1954-1994), whereas the other land regions for the most part show evidence of increasing cloud cover. This paper expands on Kaiser (1998) by analyzing trends in additional meteorological variables for Chi na [station pressure (p), water vapor pressure (e), and relative humidity (rh)] and extending the total cloud amount (N) analysis an additional two years (through 1996).

  11. Scale and space dependencies of Nitrogen variability

    NASA Astrophysics Data System (ADS)

    Tarquis, A. M.; Castellanos, M. T.; Cartagena, M. C.; Ribas, F.; Cabello, M. J.; Arce, A.; Bird, N. R. A.

    2012-04-01

    In this study we use the relative entropy (E(δ)) to investigate residual effects on wheat and grain, biomass and nitrogen content, of fertigation treatments applied to a previous crop. The wheat crop covered nine subplots from a previous experiment on melon response to fertigation. Each subplot had previously received a different level of applied nitrogen and plants from the previous melon crop had already taken up the applied nitrogen. Many factors affect these variables, causing it to vary at different scales creating a non uniform distribution. E(δ), and their increments between scales, were used to identify the scale at which the variable had a maximum structure and compare with the scaling behavior of the nitrogen applied. The E(δ)is particularly appropriate for this because of does not require any prior assumptions to the structure of the data and it is easy to calculate. The results showed that the applied nitrogen through fertirrigation dominated the wheat and grain biomass response as well as nitrogen content of the whole plant; surprisingly grain nitrogen content didn't show the same structure than the applied nitrogen. At the same time, there was a noticeable structure variation in the biomass and nitrogen content at the smaller scales that correspond to the melon cropping due to uptake of the applied nitrogen by the previous crop. The E(δ) and the increments in E(δ) help us to detect changes in the scaling behavior of all the variables studied, showing at which scale there is a maximum structure. These results are in agreement with previous studies.

  12. Validity of a Residualized Dependent Variable after Pretest Covariance Adjustments: Still the Same Variable?

    ERIC Educational Resources Information Center

    Nimon, Kim; Henson, Robin K.

    2015-01-01

    The authors empirically examined whether the validity of a residualized dependent variable after covariance adjustment is comparable to that of the original variable of interest. When variance of a dependent variable is removed as a result of one or more covariates, the residual variance may not reflect the same meaning. Using the pretest-posttest…

  13. Bayesian Network Models for Local Dependence among Observable Outcome Variables

    ERIC Educational Resources Information Center

    Almond, Russell G.; Mulder, Joris; Hemat, Lisa A.; Yan, Duanli

    2009-01-01

    Bayesian network models offer a large degree of flexibility for modeling dependence among observables (item outcome variables) from the same task, which may be dependent. This article explores four design patterns for modeling locally dependent observations: (a) no context--ignores dependence among observables; (b) compensatory context--introduces…

  14. IS ACTIVE REGION CORE VARIABILITY AGE DEPENDENT?

    SciTech Connect

    Ugarte-Urra, Ignacio; Warren, Harry P.

    2012-12-10

    The presence of both steady and transient loops in active region cores has been reported from soft X-ray and extreme-ultraviolet observations of the solar corona. The relationship between the different loop populations, however, remains an open question. We present an investigation of the short-term variability of loops in the core of two active regions in the context of their long-term evolution. We take advantage of the nearly full Sun observations of STEREO and Solar Dynamics Observatory spacecraft to track these active regions as they rotate around the Sun multiple times. We then diagnose the variability of the active region cores at several instances of their lifetime using EIS/Hinode spectral capabilities. We inspect a broad range of temperatures, including for the first time spatially and temporally resolved images of Ca XIV and Ca XV lines. We find that the active region cores become fainter and steadier with time. The significant emission measure at high temperatures that is not correlated with a comparable increase at low temperatures suggests that high-frequency heating is viable. The presence, however, during the early stages, of an enhanced emission measure in the ''hot'' (3.0-4.5 MK) and ''cool'' (0.6-0.9 MK) components suggests that low-frequency heating also plays a significant role. Our results explain why there have been recent studies supporting both heating scenarios.

  15. Computer optimization program finds values for several independent variables that minimize a dependent variable

    NASA Technical Reports Server (NTRS)

    Warech, E. J.

    1967-01-01

    Computer program finds values of independent variables which minimize the dependent variable. This optimization program has been used on the F-1 and J-2 engine programs to establish minimum film coolant requirements.

  16. The Variable Transition State in Polar Additions to Pi Bonds

    ERIC Educational Resources Information Center

    Weiss, Hilton M.

    2010-01-01

    A vast majority of polar additions of Bronsted acids to alkynes involve a termolecular transition state. With strong acids, considerable positive charge is developed on carbon and Markovnikov addition predominates. In less acidic solutions, however, the reaction is much slower and the transition state more closely resembles the olefinic product.…

  17. Are Compliance-Gaining Strategies Dependent on Situational Variables?

    ERIC Educational Resources Information Center

    Jackson, Sally; Backus, Dencil

    1982-01-01

    Finds little support for previous research that the use of persuasive strategy is dependent on situational variables, such as intimacy of the interpersonal relationship and duration of the consequences of compliance or noncompliance. Concludes, rather, that the use of a strategy may depend on unanalyzed aspects of the message content. (PD)

  18. Distinguishing between state-dependent and non-state-dependent depression-related psychosocial variables.

    PubMed

    Rosenbaum, M; Lewinsohn, P M; Gotlib, I H

    1996-09-01

    The goals of this study were: (a) to determine which among a set of depression-related psychosocial variables are state-dependent; (b) to examine whether state-trait distinctions among psychosocial variables are a function of gender; and (c) to test the hypothesis that state-dependence of psychosocial variables is mostly evident in people with a history of clinical depression. Altogether, 562 participants residing in two communities completed a battery of psychosocial measures at point of entry into the study (T1) and after an average interval of 8.3 months (T2). The state-dependence of psychosocial variables was examined in two groups of participants: (a) low-high (LH: those who were low on the Center for Epidemiologic Studies Depression Scale at T1 and high at T2; N = 45); and (b) high-low (HL: those who were high at T1 and low at T2; N = 64). The following variables were found to be state-dependent: engagement in pleasant and unpleasant events; frequency of social contacts; dissatisfaction with oneself, one's neighborhood dwelling and one's friends; irrational beliefs, and positive and negative expectancies. In contrast, the following variables were not state-dependent: dissatisfaction with family and job, perception of control, and external attributions for positive and negative events. State-dependence was not moderated by age, gender or a history of depression. Possible explanations for why some variables are state-dependent and others are not state-dependent are offered.

  19. Distance and azimuthal dependence of ground-motion variability

    NASA Astrophysics Data System (ADS)

    Vyas, Jagdish Chandra; Mai, Paul Martin; Galis, Martin

    2016-04-01

    We investigate the near-field ground-motion variability by computing the seismic wavefield for five previously published kinematic rupture models of the M 7.3 1992 Landers earthquake, several simplified rupture models based on the Landers event, and a large M 7.8 scenario earthquake in Southern California. The ground motion simulations are accomplished by solving the elasto-dynamic equations of motion using a generalized finite-difference method. The simulated waveforms are calibrated against near-field strong-motion recordings for the Landers earthquake. We then analyze our simulation-based data-set of ground-motions, binned with respect to distance and azimuth to compute mean and standard deviation of peak ground velocity (PGV). We consider different 1D-velocity-density profiles for the Landers simulations, and a 3D heterogeneous Earth structure for the ShakeOut scenario, and for both cases we honor geometrical fault complexity. The ground-motion variability, σln(PGV), estimated from numerical simulations is higher in the near-field (Joyner-Boore distance RJB <20 km) compared to that associated with standard ground-motion prediction equations. We find that σln(PGV)decreases with increasing distance from the fault as a power law. The physical explanation of a large near-field σln(PGV)is the presence of strong directivity and rupture complexity. We also show that intra-event ground-motion variability is high in the rupture-propagation direction (both forward and backward directivity regions), but low in the direction perpendicular to rupture propagation for unilateral ruptures. We observe that the power-law decay of σln(PGV) is primarily controlled by slip heterogeneity. In addition, σln(PGV) as function of azimuth is sensitive to variations in both rupture speed and slip heterogeneity. We also find that the azimuthal dependence of mean, μln(PGV), can be approximated by a Cauchy-Lorentz function, which may potentially help in estimation of ground motion for

  20. Testing Dependent Correlations with Nonoverlapping Variables: A Monte Carlo Simulation

    ERIC Educational Resources Information Center

    Silver, N. Clayton; Hittner, James B.; May, Kim

    2004-01-01

    The authors conducted a Monte Carlo simulation of 4 test statistics or comparing dependent correlations with no variables in common. Empirical Type 1 error rates and power estimates were determined for K. Pearson and L. N. G. Filon's (1898) z, O. J. Dunn and V. A. Clark's (1969) z, J. H. Steiger's (1980) original modification of Dunn and Clark's…

  1. Shoulder pain and time dependent structure in wheelchair propulsion variability.

    PubMed

    Jayaraman, Chandrasekaran; Moon, Yaejin; Sosnoff, Jacob J

    2016-07-01

    Manual wheelchair propulsion places considerable repetitive mechanical strain on the upper limbs leading to shoulder injury and pain. While recent research indicates that the amount of variability in wheelchair propulsion and shoulder pain may be related. There has been minimal inquiry into the fluctuation over time (i.e. time-dependent structure) in wheelchair propulsion variability. Consequently the purpose of this investigation was to examine if the time-dependent structure in the wheelchair propulsion parameters are related to shoulder pain. 27 experienced wheelchair users manually propelled their own wheelchair fitted with a SMARTWheel on a roller at 1.1m/s for 3min. Time-dependent structure of cycle-to-cycle fluctuations in contact angle and inter push time interval was quantified using sample entropy (SampEn) and compared between the groups with/without shoulder pain using non-parametric statistics. Overall findings were, (1) variability observed in contact angle fluctuations during manual wheelchair propulsion is structured (Z=3.15;p<0.05), (2) individuals with shoulder pain exhibited higher SampEn magnitude for contact angle during wheelchair propulsion than those without pain (χ(2)(1)=6.12;p<0.05); and (3) SampEn of contact angle correlated significantly with self-reported shoulder pain (rs (WUSPI) =0.41;rs (VAS)=0.56;p<0.05). It was concluded that the time-dependent structure in wheelchair propulsion may provide novel information for tracking and monitoring shoulder pain.

  2. The discovery of timescale-dependent color variability of quasars

    SciTech Connect

    Sun, Yu-Han; Wang, Jun-Xian; Chen, Xiao-Yang; Zheng, Zhen-Ya E-mail: jxw@ustc.edu.cn

    2014-09-01

    Quasars are variable on timescales from days to years in UV/optical and generally appear bluer while they brighten. The physics behind the variations in fluxes and colors remains unclear. Using Sloan Digital Sky Survey g- and r-band photometric monitoring data for quasars in Stripe 82, we find that although the flux variation amplitude increases with timescale, the color variability exhibits the opposite behavior. The color variability of quasars is prominent at timescales as short as ∼10 days, but gradually reduces toward timescales up to years. In other words, the variable emission at shorter timescales is bluer than that at longer timescales. This timescale dependence is clearly and consistently detected at all redshifts from z = 0 to 3.5; thus, it cannot be due to contamination to broadband photometry from emission lines that do not respond to fast continuum variations. The discovery directly rules out the possibility that simply attributes the color variability to contamination from a non-variable redder component such as the host galaxy. It cannot be interpreted as changes in global accretion rate either. The thermal accretion disk fluctuation model is favored in the sense that fluctuations in the inner, hotter region of the disk are responsible for short-term variations, while longer-term and stronger variations are expected from the larger and cooler disk region. An interesting implication is that one can use quasar variations at different timescales to probe disk emission at different radii.

  3. Smoke optical depths - Magnitude, variability, and wavelength dependence

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Russell, P. B.; Colburn, D. A.; Ackerman, T. P.; Allen, D. A.

    1988-01-01

    An airborne autotracking sun-photometer has been used to measure magnitudes, temporal/spatial variabilities, and the wavelength dependence of optical depths in the near-ultraviolet to near-infrared spectrum of smoke from two forest fires and one jet fuel fire and of background air. Jet fuel smoke optical depths were found to be generally less wavelength dependent than background aerosol optical depths. Forest fire smoke optical depths, however, showed a wide range of wavelength depedences, such as incidents of wavelength-independent extinction.

  4. Ultraviolet variability of quasars: dependence on the accretion rate

    NASA Astrophysics Data System (ADS)

    Meusinger, H.; Weiss, V.

    2013-12-01

    Aims: Although the variability in the ultraviolet and optical domain is one of the major characteristics of quasars, the dominant underlying mechanisms are still poorly understood. There is a broad consensus on the relationship between the strength of the variability and such quantities as time-lag, wavelength, luminosity, and redshift. However, evidence on a dependence on the fundamental parameters of the accretion process is still inconclusive. This paper is focused on the correlation between the ultraviolet quasar long-term variability and the accretion rate. Methods: We compiled a catalogue of about 4000 quasars including individual estimators for the variability strength derived from the multi-epoch photometry in the SDSS Stripe 82, virial black hole masses M derived from the Mg ii line, and mass accretion rates Ṁ from the Davis-Laor scaling relation. Several statistical tests were applied to evaluate the correlations of the variability with luminosity, mass, Eddington ratio, and accretion rate. Results: We confirm the existence of significant anti-correlations between the variability estimator V and the accretion rate Ṁ, the Eddington ratio ɛ, and the bolometric luminosity Lbol, respectively. The Eddington ratio is tightly correlated with Ṁ. A weak, statistically not significant positive trend is indicated for the dependence of V on M. As a side product, we find a strong correlation of the radiative efficiency η with M in our sample. We show via numerical simulations that this trend is most likely produced by selection effects in combination with the mass errors and the use of the scaling relation for Ṁ. The anti-correlations of V with Ṁ, ɛ, and Lbol cannot be explained in such a way. The strongest anti-correlation is found between V and Ṁ. However, it is difficult to decide which of the quantities L,ɛ, and Ṁ is intrinsically correlated with V and which of the observed correlations of V are produced by the L - ɛ - Ṁ relation. A V -

  5. Shoulder pain and time dependent structure in wheelchair propulsion variability.

    PubMed

    Jayaraman, Chandrasekaran; Moon, Yaejin; Sosnoff, Jacob J

    2016-07-01

    Manual wheelchair propulsion places considerable repetitive mechanical strain on the upper limbs leading to shoulder injury and pain. While recent research indicates that the amount of variability in wheelchair propulsion and shoulder pain may be related. There has been minimal inquiry into the fluctuation over time (i.e. time-dependent structure) in wheelchair propulsion variability. Consequently the purpose of this investigation was to examine if the time-dependent structure in the wheelchair propulsion parameters are related to shoulder pain. 27 experienced wheelchair users manually propelled their own wheelchair fitted with a SMARTWheel on a roller at 1.1m/s for 3min. Time-dependent structure of cycle-to-cycle fluctuations in contact angle and inter push time interval was quantified using sample entropy (SampEn) and compared between the groups with/without shoulder pain using non-parametric statistics. Overall findings were, (1) variability observed in contact angle fluctuations during manual wheelchair propulsion is structured (Z=3.15;p<0.05), (2) individuals with shoulder pain exhibited higher SampEn magnitude for contact angle during wheelchair propulsion than those without pain (χ(2)(1)=6.12;p<0.05); and (3) SampEn of contact angle correlated significantly with self-reported shoulder pain (rs (WUSPI) =0.41;rs (VAS)=0.56;p<0.05). It was concluded that the time-dependent structure in wheelchair propulsion may provide novel information for tracking and monitoring shoulder pain. PMID:27134151

  6. Alcohol-dependence syndrome: Postural challenge on heart rate variability

    PubMed Central

    Sucharita, S.; Pradeep, Johnson; Vincent, Anoop; Vaz, M.; Srinivasan, K.

    2012-01-01

    Background: Cardiac autonomic involvement in Alcohol-Dependence Syndrome (ADS) patients has been demonstrated using conventional autonomic tests. Resting heart rate variability (HRV) without normalization has also been reported. Aims: To evaluate cardiac autonomic changes with postural challenge using HRV in ADS and controls while controlling for confounding factors. Settings and Design: Cross-sectional study involving 27 male subjects with ADS and age-matched healthy controls. Materials and Methods: Clinical assessments included Schedules for Clinical Assessment in Neuropsychiatry and Severity of Alcohol Dependence Questionnaire. Spectral measures of HRV while lying and with active standing were assessed. Results: There was an attenuated response in delta high-frequency (P=0.06) and delta low-frequency (P=0.04) power to standing in ADS subjects compared with controls. Conclusion: Patients with ADS appear to have attenuated cardiac vagal and sympathetic responses to standing. HRV with postural challenge may help earlier recognition of autonomic dysfunction in ADS. PMID:23226850

  7. Generalized additive modeling with implicit variable selection by likelihood-based boosting.

    PubMed

    Tutz, Gerhard; Binder, Harald

    2006-12-01

    The use of generalized additive models in statistical data analysis suffers from the restriction to few explanatory variables and the problems of selection of smoothing parameters. Generalized additive model boosting circumvents these problems by means of stagewise fitting of weak learners. A fitting procedure is derived which works for all simple exponential family distributions, including binomial, Poisson, and normal response variables. The procedure combines the selection of variables and the determination of the appropriate amount of smoothing. Penalized regression splines and the newly introduced penalized stumps are considered as weak learners. Estimates of standard deviations and stopping criteria, which are notorious problems in iterative procedures, are based on an approximate hat matrix. The method is shown to be a strong competitor to common procedures for the fitting of generalized additive models. In particular, in high-dimensional settings with many nuisance predictor variables it performs very well. PMID:17156269

  8. Use of generalised additive models to categorise continuous variables in clinical prediction

    PubMed Central

    2013-01-01

    Background In medical practice many, essentially continuous, clinical parameters tend to be categorised by physicians for ease of decision-making. Indeed, categorisation is a common practice both in medical research and in the development of clinical prediction rules, particularly where the ensuing models are to be applied in daily clinical practice to support clinicians in the decision-making process. Since the number of categories into which a continuous predictor must be categorised depends partly on the relationship between the predictor and the outcome, the need for more than two categories must be borne in mind. Methods We propose a categorisation methodology for clinical-prediction models, using Generalised Additive Models (GAMs) with P-spline smoothers to determine the relationship between the continuous predictor and the outcome. The proposed method consists of creating at least one average-risk category along with high- and low-risk categories based on the GAM smooth function. We applied this methodology to a prospective cohort of patients with exacerbated chronic obstructive pulmonary disease. The predictors selected were respiratory rate and partial pressure of carbon dioxide in the blood (PCO2), and the response variable was poor evolution. An additive logistic regression model was used to show the relationship between the covariates and the dichotomous response variable. The proposed categorisation was compared to the continuous predictor as the best option, using the AIC and AUC evaluation parameters. The sample was divided into a derivation (60%) and validation (40%) samples. The first was used to obtain the cut points while the second was used to validate the proposed methodology. Results The three-category proposal for the respiratory rate was ≤ 20;(20,24];> 24, for which the following values were obtained: AIC=314.5 and AUC=0.638. The respective values for the continuous predictor were AIC=317.1 and AUC=0.634, with no statistically

  9. Characterizing heart rate variability by scale-dependent Lyapunov exponent

    NASA Astrophysics Data System (ADS)

    Hu, Jing; Gao, Jianbo; Tung, Wen-wen

    2009-06-01

    Previous studies on heart rate variability (HRV) using chaos theory, fractal scaling analysis, and many other methods, while fruitful in many aspects, have produced much confusion in the literature. Especially the issue of whether normal HRV is chaotic or stochastic remains highly controversial. Here, we employ a new multiscale complexity measure, the scale-dependent Lyapunov exponent (SDLE), to characterize HRV. SDLE has been shown to readily characterize major models of complex time series including deterministic chaos, noisy chaos, stochastic oscillations, random 1/f processes, random Levy processes, and complex time series with multiple scaling behaviors. Here we use SDLE to characterize the relative importance of nonlinear, chaotic, and stochastic dynamics in HRV of healthy, congestive heart failure, and atrial fibrillation subjects. We show that while HRV data of all these three types are mostly stochastic, the stochasticity is different among the three groups.

  10. Dependence of NAO variability on coupling with sea ice

    NASA Astrophysics Data System (ADS)

    Strong, Courtenay; Magnusdottir, Gudrun

    2011-05-01

    The variance of the North Atlantic Oscillation index (denoted N) is shown to depend on its coupling with area-averaged sea ice concentration anomalies in and around the Barents Sea (index denoted B). The observed form of this coupling is a negative feedback whereby positive N tends to produce negative B, which in turn forces negative N. The effects of this feedback in the system are examined by modifying the feedback in two modeling frameworks: a statistical vector autoregressive model ( F VAR) and an atmospheric global climate model ( F CAM) customized so that sea ice anomalies on the lower boundary are stochastic with adjustable sensitivity to the model's evolving N. Experiments show that the variance of N decreases nearly linearly with the sensitivity of B to N, where the sensitivity is a measure of the negative feedback strength. Given that the sea ice concentration field has anomalies, the variance of N goes down as these anomalies become more sensitive to N. If the sea ice concentration anomalies are entirely absent, the variance of N is even smaller than the experiment with the most sensitive anomalies. Quantifying how the variance of N depends on the presence and sensitivity of sea ice anomalies to N has implications for the simulation of N in global climate models. In the physical system, projected changes in sea ice thickness or extent could alter the sensitivity of B to N, impacting the within-season variability and hence predictability of N.

  11. Increased rainfall variability and N addition accelerate litter decomposition in a restored prairie.

    PubMed

    Schuster, Michael J

    2016-03-01

    Anthropogenic nitrogen deposition and projected increases in rainfall variability (the frequency of drought and heavy rainfall events) are expected to strongly influence ecosystem processes such as litter decomposition. However, how these two global change factors interact to influence litter decomposition is largely unknown. I examined how increased rainfall variability and nitrogen addition affected mass and nitrogen loss of litter from two tallgrass prairie species, Schizachyrium scoparium and Solidago canadensis, and isolated the effects of each during plant growth and during litter decomposition. I increased rainfall variability by consolidating ambient rainfall into larger events and simulated chronic nitrogen deposition using a slow-release urea fertilizer. S. scoparium litter decay was more strongly regulated by the treatments applied during plant growth than by those applied during decomposition. During plant growth, increased rainfall variability resulted in S. scoparium litter that subsequently decomposed more slowly and immobilized more nitrogen than litter grown under ambient conditions, whereas nitrogen addition during plant growth accelerated subsequent mass loss of S. scoparium litter. In contrast, S. canadensis litter mass and N losses were enhanced under either N addition or increased rainfall variability both during plant growth and during decomposition. These results suggest that ongoing changes in rainfall variability and nitrogen availability are accelerating nutrient cycling in tallgrass prairies through their combined effects on litter quality, environmental conditions, and plant community composition. PMID:26216200

  12. Exercise Training Improves Heart Rate Variability after Methamphetamine Dependency

    PubMed Central

    Dolezal, Brett A.; Chudzynski, Joy; Dickerson, Daniel; Mooney, Larissa; Rawson, Richard A.; Garfinkel, Alan; Cooper, Christopher B.

    2014-01-01

    Purpose Heart rate variability (HRV) reflects a healthy autonomic nervous system and is increased with physical training. Methamphetamine dependence (MD) causes autonomic dysfunction and diminished HRV. We compared recently abstinent MD participants with age-matched, drug free controls (DF) and also investigated whether HRV can be improved with exercise training in the MD participants. Methods In 50 participants (MD=28; DF=22) resting heart rate (R-R intervals) was recorded over 5 min while seated using a monitor affixed to a chest strap. Previously reported time-domain (SDNN, RMSSD, pNN50) and frequency-domain (LFnu, HFnu, LF/HF) parameters of HRV were calculated with customized software. MD were randomized to thrice weekly exercise training (ME=14) or equal attention without training (MC=14) over 8 weeks. Groups were compared using paired and unpaired t-tests. Statistical significance was set at P≤0.05. Results Participant characteristics were matched between groups: age 33±6 years; body mass 82.7±12 kg, BMI 26.8±4.1 kg•min−2, mean±SD. Compared with DF, the MD group had significantly higher resting heart rate (P<0.05), LFnu, and LF/HF (P<0.001) as well as lower SDNN, RMSSD, pNN50 and HFnu (all P<0.001). At randomization, HRV indices were similar between ME and MC groups. However, after training, the ME group significantly (all P<0.001) increased SDNN (+14.7±2.0 ms, +34%), RMSSD (+19.6±4.2 ms, +63%), pNN50 (+22.6±2.7%, +173%), HFnu (+14.2±1.9, +60%) and decreased HR (−5.2±1.1 beats·min−1, −7%), LFnu (−9.6±1.5, −16%) and LF/HF (−0.7±0.3, −19%). These measures did not change from baseline in the MC group. Conclusion HRV, based on several conventional indices, was diminished in recently abstinent, methamphetamine dependent individuals. Moreover, physical training yielded a marked increase of HRV representing increased vagal modulation or improved autonomic balance. PMID:24162556

  13. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  14. Variability of interconnected wind plants: correlation length and its dependence on variability time scale

    DOE PAGES

    St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

    2015-04-02

    The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. However, how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer 'how far is far enough,' we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25–2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

  15. Variability of interconnected wind plants: correlation length and its dependence on variability time scale

    SciTech Connect

    St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

    2015-04-02

    The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. However, how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer 'how far is far enough,' we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25–2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

  16. Variability of interconnected wind plants: correlation length and its dependence on variability time scale

    NASA Astrophysics Data System (ADS)

    St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.

    2015-04-01

    The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. But how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer ‘how far is far enough,’ we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25-2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high

  17. Addition of simultaneous heat and solute transport and variable fluid viscosity to SEAWAT

    USGS Publications Warehouse

    Thorne, D.; Langevin, C.D.; Sukop, M.C.

    2006-01-01

    SEAWAT is a finite-difference computer code designed to simulate coupled variable-density ground water flow and solute transport. This paper describes a new version of SEAWAT that adds the ability to simultaneously model energy and solute transport. This is necessary for simulating the transport of heat and salinity in coastal aquifers for example. This work extends the equation of state for fluid density to vary as a function of temperature and/or solute concentration. The program has also been modified to represent the effects of variable fluid viscosity as a function of temperature and/or concentration. The viscosity mechanism is verified against an analytical solution, and a test of temperature-dependent viscosity is provided. Finally, the classic Henry-Hilleke problem is solved with the new code. ?? 2006 Elsevier Ltd. All rights reserved.

  18. How Variables Uncorrelated with the Dependent Variable Can Actually Make Excellent Predictors: The Important Suppressor Variable Case.

    ERIC Educational Resources Information Center

    Woolley, Kristin K.

    Many researchers are unfamiliar with suppressor variables and how they operate in multiple regression analyses. This paper describes the role suppressor variables play in a multiple regression model and provides practical examples that explain how they can change research results. A variable that when added as another predictor increases the total…

  19. Television as a Dependent Variable, for a Change.

    ERIC Educational Resources Information Center

    Banks, Seymour; Gupta, Rajinder

    This statistical analysis of questionnaire data from a study of 673 third, fifth and seventh grade children and their parents was made to identify individual independent variables associated with children's total amount of television viewing. The data were analyzed by the stepwise linear regression method. The theoretical model guiding the…

  20. The covariation of independent and dependant variables in neurofeedback: a proposal framework to identify cognitive processes and brain activity variables.

    PubMed

    Micoulaud-Franchi, Jean-Arthur; Quiles, Clélia; Fond, Guillaume; Cermolacce, Michel; Vion-Dury, Jean

    2014-05-01

    This methodological article proposes a framework for analysing the relationship between cognitive processes and brain activity using variables measured by neurofeedback (NF) carried out by functional Magnetic Resonance Imagery (fMRI NF). Cognitive processes and brain activity variables can be analysed as either the dependant variable or the independent variable. Firstly, we propose two traditional approaches, defined in the article as the "neuropsychological" approach (NP) and the "psychophysiology" approach (PP), to extract dependent and independent variables in NF protocols. Secondly, we suggest that NF can be inspired by the style of inquiry used in neurophenomenology. fMRI NF allows participants to experiment with his or her own cognitive processes and their effects on brain region of interest (ROI) activations simultaneously. Thus, we suggest that fMRI NF could be improved by implementing "the elicitation interview method", which allows the investigator to gather relevant verbatim from participants' introspection on subjective experiences.

  1. On Direction of Dependence in Latent Variable Contexts

    ERIC Educational Resources Information Center

    von Eye, Alexander; Wiedermann, Wolfgang

    2014-01-01

    Approaches to determining direction of dependence in nonexperimental data are based on the relation between higher-than second-order moments on one side and correlation and regression models on the other. These approaches have experienced rapid development and are being applied in contexts such as research on partner violence, attention deficit…

  2. 34 CFR 75.534 - Training grants-automatic increases for additional dependents.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false Training grants-automatic increases for additional dependents. 75.534 Section 75.534 Education Office of the Secretary, Department of Education DIRECT GRANT PROGRAMS What Conditions Must Be Met by a Grantee? Allowable Costs § 75.534 Training...

  3. [Multiple dependent variables LS-SVM regression algorithm and its application in NIR spectral quantitative analysis].

    PubMed

    An, Xin; Xu, Shuo; Zhang, Lu-Da; Su, Shi-Guang

    2009-01-01

    In the present paper, on the basis of LS-SVM algorithm, we built a multiple dependent variables LS-SVM (MLS-SVM) regression model whose weights can be optimized, and gave the corresponding algorithm. Furthermore, we theoretically explained the relationship between MLS-SVM and LS-SVM. Sixty four broomcorn samples were taken as experimental material, and the sample ratio of modeling set to predicting set was 51 : 13. We first selected randomly and uniformly five weight groups in the interval [0, 1], and then in the way of leave-one-out (LOO) rule determined one appropriate weight group and parameters including penalizing parameters and kernel parameters in the model according to the criterion of the minimum of average relative error. Then a multiple dependent variables quantitative analysis model was built with NIR spectrum and simultaneously analyzed three chemical constituents containing protein, lysine and starch. Finally, the average relative errors between actual values and predicted ones by the model of three components for the predicting set were 1.65%, 6.47% and 1.37%, respectively, and the correlation coefficients were 0.9940, 0.8392 and 0.8825, respectively. For comparison, LS-SVM was also utilized, for which the average relative errors were 1.68%, 6.25% and 1.47%, respectively, and the correlation coefficients were 0.9941, 0.8310 and 0.8800, respectively. It is obvious that MLS-SVM algorithm is comparable to LS-SVM algorithm in modeling analysis performance, and both of them can give satisfying results. The result shows that the model with MLS-SVM algorithm is capable of doing multi-components NIR quantitative analysis synchronously. Thus MLS-SVM algorithm offers a new multiple dependent variables quantitative analysis approach for chemometrics. In addition, the weights have certain effect on the prediction performance of the model with MLS-SVM, which is consistent with our intuition and is validated in this study. Therefore, it is necessary to optimize

  4. Independent Sampling vs Interitem Dependencies in Whole Report Processing: Contributions of Processing Architecture and Variable Attention.

    PubMed

    Busey, Thomas A.; Townsend, James T.

    2001-04-01

    All current models of visual whole report processing assume perceptual independence among the displayed items in which the perceptual processing of individual items is not affected by other items in the display. However, models proposed by Townsend (1981, Acta Psychologica 47, 149-173), Shibuya and Bundesen (1988, Journal of Experimental Psychology: Human Perception and Performance 14, 591-600), and Bundesen (1990, Psychological Review 97, 523-547) contain postperceptual buffers that must predict negative dependencies. The perceptual-independence assumption forms what we term the modal model class. A recent example of a model that assumes perceptual independence is the Independent Sampling Model of Loftus, Busey, and Senders (1993, Perception and Psychophysics 54, 535-554). The fundamental independence assumption has only been directly tested once before, where tests revealed no dependencies except those produced by guessing. The present study tests the independence assumption using several different statistics and, contrary to most extant models of whole report, finds significant positive dependence. Poisson models do predict a positive dependence and we develop a succinctly parameterized version, the Weighted Path Poisson Model, which allows the finishing order to be a weighted probabilistic mechanism. However, it does not predict the data quite as well as a new model, the Variable Attention Model, which allows independence within trials (unlike the Poisson models). This model assumes that attention (or, potentially, other aspects such as signal quality) varies widely across trials, thus predicting an overall positive dependence. Intuitions for and against the competing models are discussed. In addition, we show, through mimicking formulae, that models which contain the proper qualitative type of dependence structure can be cast in either serial or parallel form. Copyright 2001 Academic Press.

  5. Electron paramagnetic resonance in irradiated fingernails: variability of dose dependence and possibilities of initial dose assessment.

    PubMed

    Reyes, R A; Romanyukha, Alexander; Olsen, C; Trompier, F; Benevides, L A

    2009-08-01

    The results of electron paramagnetic resonance (EPR) measurements in irradiated fingernails are presented. In total, 83 samples of different fingernails were studied. Five different groups of samples were selected based on the collection time of fingernail samples, their level of mechanical stress, and the number and size of clippings: (1) recently (<24 h) cut, irradiated and measured with EPR without any treatment of samples, and with rigorous control of size and number of clippings (stressed-fresh, controlled); (2) recently (<24 h) cut, irradiated and measured with EPR after application of a special treatment (10 min of water soaking, 5 min of drying time) to reduce the mechanical stress caused by cutting the samples, and with rigorous control of size and number of clippings (unstressed-fresh, controlled); (3) previously (>24 h) cut, stored at room temperature, additionally cut into small pieces immediately prior to study, irradiated and measured with EPR without any treatment of samples, and with rigorous control of size and number of clippings (stressed-old, controlled); (4) previously (>24 h) cut, stored at room temperature, additionally cut into small pieces immediately prior to the study, irradiated and measured with EPR after application of a special treatment to reduce mechanical stress caused by cut, and with rigorous control of size and number of clippings (unstressed-old, controlled); and (5) recently (<24 h) cut, irradiated and measured with EPR after application of a special treatment to reduce the mechanical stress caused by cut, and without rigorous control of size and number of clippings (unstressed-fresh, uncontrolled). Except for the fifth selected group, variability of the dose dependence inside all groups was found to be not statistically significant, although the variability among the different groups was significant. Comparison of the mean dose dependences obtained for each group allowed selection of key factors responsible for radiation

  6. Spectral variability of deciduous leaves depending on the developmental stages and tree condition

    NASA Astrophysics Data System (ADS)

    Song, Y.; Ryu, Y.

    2013-12-01

    Foliar spectral characteristics could be the key information in modeling forest ecosystem and the remote sensing of vegetation identification. But it is not easy to determine a typical leaf spectrum of a species in a standardized state. That is because of variables critically influencing on the spectral property of leaves, such as inter- and intra-species features, phenological phase, or biotic and abiotic stress. In this study, we attempted to quantify the spectral variability of leaves depending on species, developmental stages, and the condition of trees. The contribution of these factors to the spectral variation was analyzed at the single leaf level, with a large number of samples from deciduous plants in the urban forested area. First, we collected tens of leaf-samples at every biweekly fieldwork in the growing season, for the selected 5 tree species popular in urban parks; Acer palmatum, Carpinus laxiflora, Prunus yedoensis, Quercus acutissima, and Zelkova serrata. And absorbance, reflectance and transmittance spectra of the leaves were acquired at the short-visible (400-700 nm) to infrared (700-2500 nm) spectral region with 1 nm interval. Seasonality in these leaf-spectra was used to understand the inter-species variation depending on developmental stages. Second, as a benchmark for testing intra-species variability and differences by tree condition, we additionally analyzed the spectral reflectance of 504 ripe leaves from 56 cherry trees (Cerasus × yedoensis) collected in the middle of summer. Last, using ANOVA (analysis of variance) and general linear model, we assessed the influence of our tested variables (i.e., species, developmental stage, and tree condition) on the spectral characteristics and their vegetation indices. As a result, we clarified that the changes in leaf-spectra was apparent across all the tested species during the growing season from May to June, indicating the increasing trend of absorbance in photosynthetically active radiation

  7. Multiple correlation computer program determines relationships between several independent and dependent variables

    NASA Technical Reports Server (NTRS)

    Kaspar, H.; Newsbaum, J. B.

    1967-01-01

    Relationships between independent and dependent variables are determined by multiple correlation computer program. This is applied to research and experimental design and development of complex hardware and components that require test programs.

  8. Variable selection in covariate dependent random partition models: an application to urinary tract infection.

    PubMed

    Barcella, William; Iorio, Maria De; Baio, Gianluca; Malone-Lee, James

    2016-04-15

    Lower urinary tract symptoms can indicate the presence of urinary tract infection (UTI), a condition that if it becomes chronic requires expensive and time consuming care as well as leading to reduced quality of life. Detecting the presence and gravity of an infection from the earliest symptoms is then highly valuable. Typically, white blood cell (WBC) count measured in a sample of urine is used to assess UTI. We consider clinical data from 1341 patients in their first visit in which UTI (i.e. WBC ≥ 1) is diagnosed. In addition, for each patient, a clinical profile of 34 symptoms was recorded. In this paper, we propose a Bayesian nonparametric regression model based on the Dirichlet process prior aimed at providing the clinicians with a meaningful clustering of the patients based on both the WBC (response variable) and possible patterns within the symptoms profiles (covariates). This is achieved by assuming a probability model for the symptoms as well as for the response variable. To identify the symptoms most associated to UTI, we specify a spike and slab base measure for the regression coefficients: this induces dependence of symptoms selection on cluster assignment. Posterior inference is performed through Markov Chain Monte Carlo methods. PMID:26536840

  9. The biobehavioral family model: testing social support as an additional exogenous variable.

    PubMed

    Woods, Sarah B; Priest, Jacob B; Roush, Tara

    2014-12-01

    This study tests the inclusion of social support as a distinct exogenous variable in the Biobehavioral Family Model (BBFM). The BBFM is a biopsychosocial approach to health that proposes that biobehavioral reactivity (anxiety and depression) mediates the relationship between family emotional climate and disease activity. Data for this study included married, English-speaking adult participants (n = 1,321; 55% female; M age = 45.2 years) from the National Comorbidity Survey Replication, a nationally representative epidemiological study of the frequency of mental disorders in the United States. Participants reported their demographics, marital functioning, social support from friends and relatives, anxiety and depression (biobehavioral reactivity), number of chronic health conditions, and number of prescription medications. Confirmatory factor analyses supported the items used in the measures of negative marital interactions, social support, and biobehavioral reactivity, as well as the use of negative marital interactions, friends' social support, and relatives' social support as distinct factors in the model. Structural equation modeling indicated a good fit of the data to the hypothesized model (χ(2)  = 846.04, p = .000, SRMR = .039, CFI = .924, TLI = .914, RMSEA = .043). Negative marital interactions predicted biobehavioral reactivity (β = .38, p < .001), as did relatives' social support, inversely (β = -.16, p < .001). Biobehavioral reactivity predicted disease activity (β = .40, p < .001) and was demonstrated to be a significant mediator through tests of indirect effects. Findings are consistent with previous tests of the BBFM with adult samples, and suggest the important addition of family social support as a predicting factor in the model. PMID:24981970

  10. The biobehavioral family model: testing social support as an additional exogenous variable.

    PubMed

    Woods, Sarah B; Priest, Jacob B; Roush, Tara

    2014-12-01

    This study tests the inclusion of social support as a distinct exogenous variable in the Biobehavioral Family Model (BBFM). The BBFM is a biopsychosocial approach to health that proposes that biobehavioral reactivity (anxiety and depression) mediates the relationship between family emotional climate and disease activity. Data for this study included married, English-speaking adult participants (n = 1,321; 55% female; M age = 45.2 years) from the National Comorbidity Survey Replication, a nationally representative epidemiological study of the frequency of mental disorders in the United States. Participants reported their demographics, marital functioning, social support from friends and relatives, anxiety and depression (biobehavioral reactivity), number of chronic health conditions, and number of prescription medications. Confirmatory factor analyses supported the items used in the measures of negative marital interactions, social support, and biobehavioral reactivity, as well as the use of negative marital interactions, friends' social support, and relatives' social support as distinct factors in the model. Structural equation modeling indicated a good fit of the data to the hypothesized model (χ(2)  = 846.04, p = .000, SRMR = .039, CFI = .924, TLI = .914, RMSEA = .043). Negative marital interactions predicted biobehavioral reactivity (β = .38, p < .001), as did relatives' social support, inversely (β = -.16, p < .001). Biobehavioral reactivity predicted disease activity (β = .40, p < .001) and was demonstrated to be a significant mediator through tests of indirect effects. Findings are consistent with previous tests of the BBFM with adult samples, and suggest the important addition of family social support as a predicting factor in the model.

  11. Response additivity: effects of superimposed free reinforcement on a variable-interval baseline.

    PubMed

    Boakes, R A; Halliday, M S; Poli, M

    1975-03-01

    Three experiments examined the effects of superimposing free reinforcement (Free VI 30-sec) on behavior maintained by a response dependent mult VI 2-min VI 2-min schedule of reinforcement. Experiment I used pigeons as subjects, key pecking as the response, and colors of response key as the stimuli associated with the multiple-schedule components. When free reinforcement was added during only one component (Differential condition) a large and highly significant increase in response rate developed in this component. Adding free reinforcement during both components (Nondifferential condition) produced smaller and far less-consistent effects. An entirely different pattern of results was obtained in two subsequent experiments, where similar procedures and reinforcement conditions were used with rats as subjects and bar pressing as the response. In both Experiments II and III, response rates decreased to the stimulus associated with added free reinforcement in the Differential condition. These findings are interpreted as the result of interactions between behavior maintained by response-reinforcer contingencies and behavior maintained by stimulus-reinforcer contingencies. As such, they support the main assumption of an autoshaping theory of behavioral contrast, that additivity of responding generated by the two kinds of contingency can occur only in situations favorable to autoshaping.

  12. A Bayesian Alternative to Mutual Information for the Hierarchical Clustering of Dependent Random Variables

    PubMed Central

    Marrelec, Guillaume; Messé, Arnaud; Bellec, Pierre

    2015-01-01

    The use of mutual information as a similarity measure in agglomerative hierarchical clustering (AHC) raises an important issue: some correction needs to be applied for the dimensionality of variables. In this work, we formulate the decision of merging dependent multivariate normal variables in an AHC procedure as a Bayesian model comparison. We found that the Bayesian formulation naturally shrinks the empirical covariance matrix towards a matrix set a priori (e.g., the identity), provides an automated stopping rule, and corrects for dimensionality using a term that scales up the measure as a function of the dimensionality of the variables. Also, the resulting log Bayes factor is asymptotically proportional to the plug-in estimate of mutual information, with an additive correction for dimensionality in agreement with the Bayesian information criterion. We investigated the behavior of these Bayesian alternatives (in exact and asymptotic forms) to mutual information on simulated and real data. An encouraging result was first derived on simulations: the hierarchical clustering based on the log Bayes factor outperformed off-the-shelf clustering techniques as well as raw and normalized mutual information in terms of classification accuracy. On a toy example, we found that the Bayesian approaches led to results that were similar to those of mutual information clustering techniques, with the advantage of an automated thresholding. On real functional magnetic resonance imaging (fMRI) datasets measuring brain activity, it identified clusters consistent with the established outcome of standard procedures. On this application, normalized mutual information had a highly atypical behavior, in the sense that it systematically favored very large clusters. These initial experiments suggest that the proposed Bayesian alternatives to mutual information are a useful new tool for hierarchical clustering. PMID:26406245

  13. Load-dependent Optimization of Honeycombs for Sandwich Components - New Possibilities by Using Additive Layer Manufacturing

    NASA Astrophysics Data System (ADS)

    Riss, Fabian; Schilp, Johannes; Reinhart, Gunther

    Due to their feasible geometric complexity, additive layer manufacturing (ALM) processes show a highpotential for the production of lightweight components.Therefore, ALM processes enable the realization of bionic-designedcomponents like honeycombs, which are optimized depending upon load and outer boundary conditions.This optimization is based on a closed-loop, three-steps methodology: At first, each honeycomb is conformed to the surface of the part. Secondly, the structure is optimizedfor lightweight design.It is possible to achieve a homogeneous stress distribution in the part by varying the wall thickness, honeycombdiameter and the amount of honeycombs, depending on the subjected stresses and strains. At last, the functional components like threads or bearing carriers are integrated directly into the honeycomb core.Using all these steps as an iterative process, it is possible to reduce the mass of sandwich components about 50 percent compared to conventional approaches.

  14. A WntD-Dependent Integral Feedback Loop Attenuates Variability in Drosophila Toll Signaling.

    PubMed

    Rahimi, Neta; Averbukh, Inna; Haskel-Ittah, Michal; Degani, Neta; Schejter, Eyal D; Barkai, Naama; Shilo, Ben-Zion

    2016-02-22

    Patterning by morphogen gradients relies on the capacity to generate reproducible distribution profiles. Morphogen spread depends on kinetic parameters, including diffusion and degradation rates, which vary between embryos, raising the question of how variability is controlled. We examined this in the context of Toll-dependent dorsoventral (DV) patterning of the Drosophila embryo. We find that low embryo-to-embryo variability in DV patterning relies on wntD, a Toll-target gene expressed initially at the posterior pole. WntD protein is secreted and disperses in the extracellular milieu, associates with its receptor Frizzled4, and inhibits the Toll pathway by blocking the Toll extracellular domain. Mathematical modeling predicts that WntD accumulates until the Toll gradient narrows to its desired spread, and we support this feedback experimentally. This circuit exemplifies a broadly applicable induction-contraction mechanism, which reduces patterning variability through a restricted morphogen-dependent expression of a secreted diffusible inhibitor. PMID:26906736

  15. Dependence of vestibular reactions on frequency of action of sign-variable accelerations

    NASA Technical Reports Server (NTRS)

    Lapayev, E. V.; Vorobyev, O. A.; Ivanov, V. V.

    1980-01-01

    It was revealed that during the tests with continuous action of sign variable Coriolis acceleration the development of kinetosis was proportionate to the time of head inclinations in the range of 1 to 4 seconds while illusions of rocking in sagittal plane was more expressed in fast inclinations. The obtained data provided the evidence of sufficient dependence of vestibulovegetative and vestibulosensory reactions on the period of repetition of sign variable Coriolis acceleration.

  16. On the dependence of QCD splitting functions on the choice of the evolution variable

    NASA Astrophysics Data System (ADS)

    Jadach, S.; Kusina, A.; Placzek, W.; Skrzypek, M.

    2016-08-01

    We show that already at the NLO level the DGLAP evolution kernel P qq starts to depend on the choice of the evolution variable. We give an explicit example of such a variable, namely the maximum of transverse momenta of emitted partons and we identify a class of evolution variables that leave the NLO P qq kernel unchanged with respect to the known standard overline{MS} results. The kernels are calculated using a modified Curci-Furmanski-Petronzio method which is based on a direct Feynman-graphs calculation.

  17. Vagal-dependent nonlinear variability in the respiratory pattern of anesthetized, spontaneously breathing rats

    PubMed Central

    Dhingra, R. R.; Jacono, F. J.; Fishman, M.; Loparo, K. A.; Rybak, I. A.

    2011-01-01

    Physiological rhythms, including respiration, exhibit endogenous variability associated with health, and deviations from this are associated with disease. Specific changes in the linear and nonlinear sources of breathing variability have not been investigated. In this study, we used information theory-based techniques, combined with surrogate data testing, to quantify and characterize the vagal-dependent nonlinear pattern variability in urethane-anesthetized, spontaneously breathing adult rats. Surrogate data sets preserved the amplitude distribution and linear correlations of the original data set, but nonlinear correlation structure in the data was removed. Differences in mutual information and sample entropy between original and surrogate data sets indicated the presence of deterministic nonlinear or stochastic non-Gaussian variability. With vagi intact (n = 11), the respiratory cycle exhibited significant nonlinear behavior in templates of points separated by time delays ranging from one sample to one cycle length. After vagotomy (n = 6), even though nonlinear variability was reduced significantly, nonlinear properties were still evident at various time delays. Nonlinear deterministic variability did not change further after subsequent bilateral microinjection of MK-801, an N-methyl-d-aspartate receptor antagonist, in the Kölliker-Fuse nuclei. Reversing the sequence (n = 5), blocking N-methyl-d-aspartate receptors bilaterally in the dorsolateral pons significantly decreased nonlinear variability in the respiratory pattern, even with the vagi intact, and subsequent vagotomy did not change nonlinear variability. Thus both vagal and dorsolateral pontine influences contribute to nonlinear respiratory pattern variability. Furthermore, breathing dynamics of the intact system are mutually dependent on vagal and pontine sources of nonlinear complexity. Understanding the structure and modulation of variability provides insight into disease effects on respiratory

  18. Further results on delay-range-dependent stability with additive time-varying delay systems.

    PubMed

    Liu, Pin-Lin

    2014-03-01

    In this paper, new conditions for the delay-range-dependent stability analysis of time-varying delay systems are proposed in a Lyapunov-Krasovskii framework. Time delay is considered to be time-varying and has lower and upper bounds. A new method is first presented for a system with two time delays, integral inequality approach (IIA) used to express relationships among terms of Leibniz-Newton formula. Constructing a novel Lyapunov-Krasovskii functional includes information belonging to a given range; new delay-range-dependent criterion is established in term of linear matrix inequality (LMI). The advantage of that criterion lies in its simplicity and less conservative. This paper also presents a new result of stability analysis for continuous systems with two additive time-variant components representing a general class of delay with strong application background in network-based control systems. Resulting criteria are then expressed in terms of convex optimization with LMI constraints, allowing for use of efficient solvers. Finally, three numerical examples show these methods reducing conservatism and improving maximal allowable delay.

  19. ADDITIONAL DEMOGRAPHIC AND CLINICAL EVIDENCES ON THE RELEVANCE OF THE SYSTEMIC THERAPY IN ALCOHOL DEPENDENCE.

    PubMed

    Alexinschi, Ovidiu; Chirita, Roxana; Manuela, Padurariu; Ciobica, Alin; Dobrin, Romeo; Petrariu, F D; Timofte, Daniel; Chirita, Vasile

    2015-01-01

    The modern treatment for alcohol dependence is still problematic, in many cases with the costs exceeding benefits. In these conditions a new management approach was developed lately, known as the systemic therapy. In this way, the crystallization and practical transposition of this new treatment approach is represented by the Clubs of Alcoholics in Treatment. These clubs are in fact a form of psycho-social intervention consisting of multi-family communities in order to maintain long-term abstinence from alcohol and to change their lifestyle and behavior. Thus, in the present paper we were interested in understanding the demographics of this systemic theory and how these aspects are influencing the final results of the therapy, as well as studying/confirming how relevant is this systemic approach on the management of alcohol dependence. Our results presented in this report bring additional evidences for the superiority of the systemic, multi-family approach of alcohol-related problems, as complemented to the standard medicinal therapy. Moreover, the data collected from patients in this study might suggest that patients with a higher educational level and therefore better capacity of understanding the information, with family support, and also with a better occupational insertion, have accepted to follow The Clubs of Alcoholics in Treatment program, with a subsequently better evolution. PMID:26793858

  20. Baseline-dependent effect of noise-enhanced insoles on gait variability in healthy elderly walkers.

    PubMed

    Stephen, Damian G; Wilcox, Bethany J; Niemi, James B; Franz, Jason R; Franz, Jason; Kerrigan, Dr; Kerrigan, D Casey; D'Andrea, Susan E

    2012-07-01

    The purpose of this study was to determine whether providing subsensory stochastic-resonance mechanical vibration to the foot soles of elderly walkers could decrease gait variability. In a randomized double-blind controlled trial, 29 subjects engaged in treadmill walking while wearing sandals customized with three actuators capable of producing stochastic-resonance mechanical vibration embedded in each sole. For each subject, we determined a subsensory level of vibration stimulation. After a 5-min acclimation period of walking with the footwear, subjects were asked to walk on the treadmill for six trials, each 30s long. Trials were pair-wise random: in three trials, actuators provided subsensory vibration; in the other trials, they did not. Subjects wore reflective markers to track body motion. Stochastic-resonance mechanical stimulation exhibited baseline-dependent effects on spatial stride-to-stride variability in gait, slightly increasing variability in subjects with least baseline variability and providing greater reductions in variability for subjects with greater baseline variability (p<.001). Thus, applying stochastic-resonance mechanical vibrations on the plantar surface of the foot reduces gait variability for subjects with more variable gait. Stochastic-resonance mechanical vibrations may provide an effective intervention for preventing falls in healthy elderly walkers.

  1. Variable, voltage-dependent, blocking effects of nitrendipine, verapamil, diltiazem, cinnarizine and cadmium on adrenomedullary secretion.

    PubMed Central

    López, M. G.; Moro, M. A.; Castillo, C. F.; Artalejo, C. R.; García, A. G.

    1989-01-01

    1. Catecholamine release from cat adrenal glands perfused at a high rate (4 ml min-1) at 37 degrees C with modified Krebs solutions lacking Ca and containing 1.2 mM K (hyperpolarizing solution) or 118 mM K (depolarizing solution) was triggered by 10-s pulses of Ca (0.5 mM) in the presence of 118 mM K. Hyperpolarized glands released 1280 +/- 135 ng per pulse and depolarized glands 831 +/- 98 ng per pulse (n = 29). 2. While the dihydropyridine Ca channel blocker nitrendipine inhibited secretion in hyperpolarized glands with an IC50 of 214 nM, in depolarizing conditions the drug was much more potent (IC50 = 0.99 nM). In contrast, the inorganic Ca channel blocker cadmium inhibited secretion with the same potency both in hyperpolarized or depolarized glands. 3. Cinnarizine, diltiazem and verapamil exhibited intermediate degrees of voltage-dependence in blocking secretion. The IC50 ratios between hyperpolarized and depolarized glands were 215, 36, 19, 8 and 0.76 respectively for nitrendipine, cinnarizine, diltiazem, verapamil and cadmium. Because the experimental design (strong depolarization in the absence of Ca) favours the highest opening probability of Ca channels, it seems that these drugs bind preferentially to their receptors when these channels are in their open state. 4. Variable voltage-dependent effects of the five Ca channel blockers on adrenomedullary catecholamine release suggests different sites and mechanisms of action on, or near L-type Ca channels in chromaffin cells. In addition, these findings might help to explain why these drugs exhibit tissue selectivity and why they act differently in normal polarized as compared to ischaemic depolarized cells. PMID:2720300

  2. The theory of planned behaviour and healthy eating: Examining additive and moderating effects of social influence variables.

    PubMed

    Povey, R; Conner, M; Sparks, P; James, R; Shepherd, R

    2000-11-01

    Abstract This paper examines the additive and moderating effects of social influence variables (injunctive norms, descriptive norms, perceived social support) within the Theory of Planned Behaviour (TPB). The target behaviour is the decision to eat healthily. Questionnaire responses on components of the TPB, descriptive norms, perceived social support, and subsequent healthy eating were obtained from a prospective sample of 235 members of the general public. Good predictions of intentions (42% of variance explained) and behaviour (15% of variance explained) were found using the Theory of Planned Behaviour. Neither descriptive norms nor perceived social support added to these predictions of intentions over and above the TPB variables. However, perceived social support was found to act as a moderator variable on the relationship between perceived behavioral control and intention, and the relationship between attitude and intention. Implications for exploring the role of social influence variables on decisions concerning health behavioun an discussed.

  3. The theory of planned behaviour and healthy eating: Examining additive and moderating effects of social influence variables.

    PubMed

    Povey, R; Conner, M; Sparks, P; James, R; Shepherd, R

    2000-11-01

    Abstract This paper examines the additive and moderating effects of social influence variables (injunctive norms, descriptive norms, perceived social support) within the Theory of Planned Behaviour (TPB). The target behaviour is the decision to eat healthily. Questionnaire responses on components of the TPB, descriptive norms, perceived social support, and subsequent healthy eating were obtained from a prospective sample of 235 members of the general public. Good predictions of intentions (42% of variance explained) and behaviour (15% of variance explained) were found using the Theory of Planned Behaviour. Neither descriptive norms nor perceived social support added to these predictions of intentions over and above the TPB variables. However, perceived social support was found to act as a moderator variable on the relationship between perceived behavioral control and intention, and the relationship between attitude and intention. Implications for exploring the role of social influence variables on decisions concerning health behavioun an discussed. PMID:22175258

  4. Field Dependency, n Power and Locus of Control Variables in Alcohol Aversion.

    ERIC Educational Resources Information Center

    Query, William T.

    1983-01-01

    Compared individual differences and treatment effectiveness in male volunteer alcoholics (N=47) in a 10-day electroconditioning aversion program. Follow-up showed combination therapy was more successful. Internals and hard liquor drinkers tended to be abstinent as predicted. Field dependency was a more unstable variable for outcome. (Author/JAC)

  5. Relationship Between Field Dependence - Field Independence, Piaget Conservation Tasks and School Variables.

    ERIC Educational Resources Information Center

    Wicker, Tommie E.; O'Tuel, Frances S.

    This study investigates relationships among conservation, field dependence/independence, school variables, achievement, screening measures, sex and race. A total of 124 first, second and third graders in a Southern rural school were administered 8 typical Piagetian conservation tasks (PCT), Children's Embedded Figures Test (CEFT), Comprehensive…

  6. DENSITY-DEPENDENT FLOW IN ONE-DIMENSIONAL VARIABLY-SATURATED MEDIA

    EPA Science Inventory

    A one-dimensional finite element is developed to simulate density-dependent flow of saltwater in variably saturated media. The flow and solute equations were solved in a coupled mode (iterative), in a partially coupled mode (non-iterative), and in a completely decoupled mode. P...

  7. Omnibus Tests for Interactions in Repeated Measures Designs with Dichotomous Dependent Variables.

    ERIC Educational Resources Information Center

    Serlin, Ronald C.; Marascuilo, Leonard A.

    When examining a repeated measures design with independent groups for a significant group by trial interaction, classical analysis of variance or multivariate procedures can be used if the assumptions underlying the tests are met. Neither procedure may be justified for designs with small sample sizes and dichotomous dependent variables. An omnibus…

  8. Distribution of Personal Income in Agriculture-Dependent Counties of Midwestern States: A Policy Variables Approach.

    ERIC Educational Resources Information Center

    Goreham, Gary A.; And Others

    Significant social, demographic, and economic changes have occurred in the North Central states since 1960. This document examines structural and policy variables related to distribution of income, during the years 1960-80 in the 397 counties defined as agriculture-dependent in 13 North Central states. Personal income distribution has been…

  9. Human Performance Technology (HPT): An Examination of Definitions through Dependent and Independent Variables.

    ERIC Educational Resources Information Center

    Irlbeck, Sonja A.

    2002-01-01

    Provides a chronological perspective of human performance technology (HPT) definitions and an evaluation of them in terms of independent and dependent variables. Discusses human competence and performance technology and compares the definitions with the goals that have been articulated for HPT. (Author/LRW)

  10. On Integrating Variables and Separating Facts in the Complex Relationship between Dependency and Domestic Violence

    ERIC Educational Resources Information Center

    Bornstein, Robert F.

    2007-01-01

    Presents a reply by Robert Bornstein to comments from Chronister and regarding his article, "The complex relationship between dependency and domestic violence: Converging psychological factors and social forces." In addition to raising some important issues regarding the link between dependency and domestic violence, the comments by Chronister and…

  11. Additive effect of ketoconazole and octreotide in the treatment of severe adrenocorticotropin-dependent hypercortisolism.

    PubMed

    Vignati, F; Loli, P

    1996-08-01

    Over the last few years ketoconazole and octreotide have been employed in the treatment of pituitary-dependent or ectopic Cushing's syndrome. In four patients (two men and two women, aged 25-64 yr) with severe ACTH-dependent hypercortisolism in whom medical treatment with ketoconazole showed limited effectiveness and/or tolerability, we tried the association with octreotide. In all patients ketoconazole (200-1000 mg) induced a marked decrease in urinary free cortisol (UFC) excretion, but normalization could not be achieved. After ketoconazole discontinuation, three patients received octreotide alone (300-1500 micrograms/day, sc). This drug caused a dramatic decrease in UFC excretion, although not normalization; in all patients, escape from treatment occurred. Combined treatment was carried out for 10-180 days. Urinary cortisol excretion normalized and remained steadily within normal limits in three of four patients in whom normal UFC excretion had never been attained with both single drug regimens; in the fourth patient, UFC excretion decreased to levels lower than those achieved with ketoconazole or octreotide alone. The association with octreotide allowed a reduction in the daily dose of ketoconazole in three patients. Consistent with the steady reduction of cortisol production, a striking clinical improvement occurred in all patients after starting combined treatment. The normalization of UFC in three of four patients treated with both agents suggests that this approach may be useful in the long term treatment of severe forms of hypercortisolism of both pituitary and ectopic origin. In contrast to the limited effectiveness of each drug taken singularly at the same or higher doses, the association of the two drugs had an additive effect in the attainment of normal urinary cortisol excretion.

  12. Reducing seed dependent variability of non-uniformly sampled multidimensional NMR data.

    PubMed

    Mobli, Mehdi

    2015-07-01

    The application of NMR spectroscopy to study the structure, dynamics and function of macromolecules requires the acquisition of several multidimensional spectra. The one-dimensional NMR time-response from the spectrometer is extended to additional dimensions by introducing incremented delays in the experiment that cause oscillation of the signal along "indirect" dimensions. For a given dimension the delay is incremented at twice the rate of the maximum frequency (Nyquist rate). To achieve high-resolution requires acquisition of long data records sampled at the Nyquist rate. This is typically a prohibitive step due to time constraints, resulting in sub-optimal data records to the detriment of subsequent analyses. The multidimensional NMR spectrum itself is typically sparse, and it has been shown that in such cases it is possible to use non-Fourier methods to reconstruct a high-resolution multidimensional spectrum from a random subset of non-uniformly sampled (NUS) data. For a given acquisition time, NUS has the potential to improve the sensitivity and resolution of a multidimensional spectrum, compared to traditional uniform sampling. The improvements in sensitivity and/or resolution achieved by NUS are heavily dependent on the distribution of points in the random subset acquired. Typically, random points are selected from a probability density function (PDF) weighted according to the NMR signal envelope. In extreme cases as little as 1% of the data is subsampled. The heavy under-sampling can result in poor reproducibility, i.e. when two experiments are carried out where the same number of random samples is selected from the same PDF but using different random seeds. Here, a jittered sampling approach is introduced that is shown to improve random seed dependent reproducibility of multidimensional spectra generated from NUS data, compared to commonly applied NUS methods. It is shown that this is achieved due to the low variability of the inherent sensitivity of the

  13. Reducing seed dependent variability of non-uniformly sampled multidimensional NMR data

    NASA Astrophysics Data System (ADS)

    Mobli, Mehdi

    2015-07-01

    The application of NMR spectroscopy to study the structure, dynamics and function of macromolecules requires the acquisition of several multidimensional spectra. The one-dimensional NMR time-response from the spectrometer is extended to additional dimensions by introducing incremented delays in the experiment that cause oscillation of the signal along "indirect" dimensions. For a given dimension the delay is incremented at twice the rate of the maximum frequency (Nyquist rate). To achieve high-resolution requires acquisition of long data records sampled at the Nyquist rate. This is typically a prohibitive step due to time constraints, resulting in sub-optimal data records to the detriment of subsequent analyses. The multidimensional NMR spectrum itself is typically sparse, and it has been shown that in such cases it is possible to use non-Fourier methods to reconstruct a high-resolution multidimensional spectrum from a random subset of non-uniformly sampled (NUS) data. For a given acquisition time, NUS has the potential to improve the sensitivity and resolution of a multidimensional spectrum, compared to traditional uniform sampling. The improvements in sensitivity and/or resolution achieved by NUS are heavily dependent on the distribution of points in the random subset acquired. Typically, random points are selected from a probability density function (PDF) weighted according to the NMR signal envelope. In extreme cases as little as 1% of the data is subsampled. The heavy under-sampling can result in poor reproducibility, i.e. when two experiments are carried out where the same number of random samples is selected from the same PDF but using different random seeds. Here, a jittered sampling approach is introduced that is shown to improve random seed dependent reproducibility of multidimensional spectra generated from NUS data, compared to commonly applied NUS methods. It is shown that this is achieved due to the low variability of the inherent sensitivity of the

  14. Enhancing quantum entanglement for continuous variables by a coherent superposition of photon subtraction and addition

    SciTech Connect

    Lee, Su-Yong; Kim, Ho-Joon; Ji, Se-Wan; Nha, Hyunchul

    2011-07-15

    We investigate how the entanglement properties of a two-mode state can be improved by performing a coherent superposition operation ta+ra{sup {dagger}} of photon subtraction and addition, proposed by Lee and Nha [Phys. Rev. A 82, 053812 (2010)], on each mode. We show that the degree of entanglement, the Einstein-Podolsky-Rosen-type correlation, and the performance of quantum teleportation can be all enhanced for the output state when the coherent operation is applied to a two-mode squeezed state. The effects of the coherent operation are more prominent than those of the mere photon subtraction a and the addition a{sup {dagger}} particularly in the small-squeezing regime, whereas the optimal operation becomes the photon subtraction (case of r=0) in the large-squeezing regime.

  15. Spatially variable synergistic effects of disturbance and additional nutrients on kelp recruitment and recovery.

    PubMed

    Carnell, Paul E; Keough, Michael J

    2014-05-01

    Understanding the impact of multiple stressors on ecosystems is of pronounced importance, particularly when one or more of those stressors is anthropogenic. Here we investigated the role of physical disturbance and increased nutrients on reefs dominated by the canopy-forming kelp Ecklonia radiata. We combined experimental kelp canopy removals and additional nutrient at three different locations in a large embayment in temperate southeastern Australia. Over the following winter recruitment season, Ecklonia recruitment was unaffected by increased nutrients alone, but tripled at all sites where the canopy had been removed. At one site, the combination of disturbance and increased nutrients resulted in more than four times the recruitment of the introduced kelp Undaria pinnatifida. Six months after disturbance, the proliferation of the Undaria canopy in the canopy-removal and nutrient-addition treatment negatively influenced the recovery of the native kelp Ecklonia. Given the otherwise competitive dominance of adult Ecklonia, this provides a mechanism whereby Undaria could maintain open space for the following recruitment season. This interplay between disturbance, nutrients and the response of native and invasive species makes a compelling case for how a combination of factors can influence species dynamics.

  16. Exocyst-Dependent Membrane Addition Is Required for Anaphase Cell Elongation and Cytokinesis in Drosophila

    PubMed Central

    Giansanti, Maria Grazia; Vanderleest, Timothy E.; Jewett, Cayla E.; Sechi, Stefano; Frappaolo, Anna; Fabian, Lacramioara; Robinett, Carmen C.; Brill, Julie A.; Loerke, Dinah; Fuller, Margaret T.; Blankenship, J. Todd

    2015-01-01

    Mitotic and cytokinetic processes harness cell machinery to drive chromosomal segregation and the physical separation of dividing cells. Here, we investigate the functional requirements for exocyst complex function during cell division in vivo, and demonstrate a common mechanism that directs anaphase cell elongation and cleavage furrow progression during cell division. We show that onion rings (onr) and funnel cakes (fun) encode the Drosophila homologs of the Exo84 and Sec8 exocyst subunits, respectively. In onr and fun mutant cells, contractile ring proteins are recruited to the equatorial region of dividing spermatocytes. However, cytokinesis is disrupted early in furrow ingression, leading to cytokinesis failure. We use high temporal and spatial resolution confocal imaging with automated computational analysis to quantitatively compare wild-type versus onr and fun mutant cells. These results demonstrate that anaphase cell elongation is grossly disrupted in cells that are compromised in exocyst complex function. Additionally, we observe that the increase in cell surface area in wild type peaks a few minutes into cytokinesis, and that onr and fun mutant cells have a greatly reduced rate of surface area growth specifically during cell division. Analysis by transmission electron microscopy reveals a massive build-up of cytoplasmic astral membrane and loss of normal Golgi architecture in onr and fun spermatocytes, suggesting that exocyst complex is required for proper vesicular trafficking through these compartments. Moreover, recruitment of the small GTPase Rab11 and the PITP Giotto to the cleavage site depends on wild-type function of the exocyst subunits Exo84 and Sec8. Finally, we show that the exocyst subunit Sec5 coimmunoprecipitates with Rab11. Our results are consistent with the exocyst complex mediating an essential, coordinated increase in cell surface area that potentiates anaphase cell elongation and cleavage furrow ingression. PMID:26528720

  17. Exocyst-Dependent Membrane Addition Is Required for Anaphase Cell Elongation and Cytokinesis in Drosophila.

    PubMed

    Giansanti, Maria Grazia; Vanderleest, Timothy E; Jewett, Cayla E; Sechi, Stefano; Frappaolo, Anna; Fabian, Lacramioara; Robinett, Carmen C; Brill, Julie A; Loerke, Dinah; Fuller, Margaret T; Blankenship, J Todd

    2015-11-01

    Mitotic and cytokinetic processes harness cell machinery to drive chromosomal segregation and the physical separation of dividing cells. Here, we investigate the functional requirements for exocyst complex function during cell division in vivo, and demonstrate a common mechanism that directs anaphase cell elongation and cleavage furrow progression during cell division. We show that onion rings (onr) and funnel cakes (fun) encode the Drosophila homologs of the Exo84 and Sec8 exocyst subunits, respectively. In onr and fun mutant cells, contractile ring proteins are recruited to the equatorial region of dividing spermatocytes. However, cytokinesis is disrupted early in furrow ingression, leading to cytokinesis failure. We use high temporal and spatial resolution confocal imaging with automated computational analysis to quantitatively compare wild-type versus onr and fun mutant cells. These results demonstrate that anaphase cell elongation is grossly disrupted in cells that are compromised in exocyst complex function. Additionally, we observe that the increase in cell surface area in wild type peaks a few minutes into cytokinesis, and that onr and fun mutant cells have a greatly reduced rate of surface area growth specifically during cell division. Analysis by transmission electron microscopy reveals a massive build-up of cytoplasmic astral membrane and loss of normal Golgi architecture in onr and fun spermatocytes, suggesting that exocyst complex is required for proper vesicular trafficking through these compartments. Moreover, recruitment of the small GTPase Rab11 and the PITP Giotto to the cleavage site depends on wild-type function of the exocyst subunits Exo84 and Sec8. Finally, we show that the exocyst subunit Sec5 coimmunoprecipitates with Rab11. Our results are consistent with the exocyst complex mediating an essential, coordinated increase in cell surface area that potentiates anaphase cell elongation and cleavage furrow ingression. PMID:26528720

  18. Heart rate variability biofeedback in patients with alcohol dependence: a randomized controlled study

    PubMed Central

    Penzlin, Ana Isabel; Siepmann, Timo; Illigens, Ben Min-Woo; Weidner, Kerstin; Siepmann, Martin

    2015-01-01

    Background and objective In patients with alcohol dependence, ethyl-toxic damage of vasomotor and cardiac autonomic nerve fibers leads to autonomic imbalance with neurovascular and cardiac dysfunction, the latter resulting in reduced heart rate variability (HRV). Autonomic imbalance is linked to increased craving and cardiovascular mortality. In this study, we sought to assess the effects of HRV biofeedback training on HRV, vasomotor function, craving, and anxiety. Methods We conducted a randomized controlled study in 48 patients (14 females, ages 25–59 years) undergoing inpatient rehabilitation treatment. In the treatment group, patients (n=24) attended six sessions of HRV biofeedback over 2 weeks in addition to standard rehabilitative care, whereas, in the control group, subjects received standard care only. Psychometric testing for craving (Obsessive Compulsive Drinking Scale), anxiety (Symptom Checklist-90-Revised), HRV assessment using coefficient of variation of R-R intervals (CVNN) analysis, and vasomotor function assessment using laser Doppler flowmetry were performed at baseline, immediately after completion of treatment or control period, and 3 and 6 weeks afterward (follow-ups 1 and 2). Results Psychometric testing showed decreased craving in the biofeedback group immediately postintervention (OCDS scores: 8.6±7.9 post-biofeedback versus 13.7±11.0 baseline [mean ± standard deviation], P<0.05), whereas craving was unchanged at this time point in the control group. Anxiety was reduced at follow-ups 1 and 2 post-biofeedback, but was unchanged in the control group (P<0.05). Following biofeedback, CVNN tended to be increased (10.3%±2.8% post-biofeedback, 10.1%±3.5% follow-up 1, 10.1%±2.9% follow-up 2 versus 9.7%±3.6% baseline; P=not significant). There was no such trend in the control group. Vasomotor function assessed using the mean duration to 50% vasoconstriction of cutaneous vessels after deep inspiration was improved following biofeedback

  19. Spatiotemporal Dependency of Age-Related Changes in Brain Signal Variability

    PubMed Central

    McIntosh, A. R.; Vakorin, V.; Kovacevic, N.; Wang, H.; Diaconescu, A.; Protzner, A. B.

    2014-01-01

    Recent theoretical and empirical work has focused on the variability of network dynamics in maturation. Such variability seems to reflect the spontaneous formation and dissolution of different functional networks. We sought to extend these observations into healthy aging. Two different data sets, one EEG (total n = 48, ages 18–72) and one magnetoencephalography (n = 31, ages 20–75) were analyzed for such spatiotemporal dependency using multiscale entropy (MSE) from regional brain sources. In both data sets, the changes in MSE were timescale dependent, with higher entropy at fine scales and lower at more coarse scales with greater age. The signals were parsed further into local entropy, related to information processed within a regional source, and distributed entropy (information shared between two sources, i.e., functional connectivity). Local entropy increased for most regions, whereas the dominant change in distributed entropy was age-related reductions across hemispheres. These data further the understanding of changes in brain signal variability across the lifespan, suggesting an inverted U-shaped curve, but with an important qualifier. Unlike earlier in maturation, where the changes are more widespread, changes in adulthood show strong spatiotemporal dependence. PMID:23395850

  20. [Gender differences in alcohol dependence: personality variables, psychopathological profile and personality disorders].

    PubMed

    Bravo de Medina, Ricardo; Echeburúa, Enrique; Aizpiri, Javier

    2008-05-01

    In this paper, gender differences in personality, psychopathology and personality disorders of alcohol-dependent patients are described. The sample consisted of 158 alcohol-dependent patients attending a psychiatric outpatient clinic (105 men and 55 women). All participants were assessed with various assessment tools related to personality (Impulsiveness Scale, Sensation Seeking Scale and STAI), psychopathology (SCL-90-R, BDI and Inadaptation Scale) and personality disorders (IPDE). There were no differences in personality variables, but the women had more anxiety and depressive symptoms and also more problems to adapt to everyday life than did the men. Personality disorders were not as prevalent as in the case of men, and the most frequent among women were obsessive-compulsive, dependent and histrionic personality disorders. Implications of this study for further research are commented on.

  1. Genetic variability in tryptophan hydroxylase 2 gene in alcohol dependence and alcohol-related psychopathological symptoms.

    PubMed

    Plemenitaš, Anja; Kores Plesničar, Blanka; Kastelic, Matej; Porcelli, Stefano; Serretti, Alessandro; Dolžan, Vita

    2015-09-14

    Heritability plays an important role in the development and expression of alcohol dependence. The present genetic association study explored the role of TPH2 polymorphisms and their haplotypes to investigate its role in alcohol dependence and comorbid psychopathological symptoms. The sample included 101 subjects currently diagnosed as alcohol abusers, 100 abstinent alcohol-dependent subjects and 97 healthy controls. Subjects were genotyped for TPH2 rs4570625, rs1843809, rs7305115, rs4290270. TPH2 genotypes were not associated with alcohol dependence, but GGAA haplotype was less common (p=0.038) and GTAA and GGGT were more common (p=0.011 and p=0.021, respectively), in currently dependent patients compared to controls. Exploratory analysis of genotypes in currently dependent patients showed that rs1843809 was associated with depressive and aggressive traits (p=0.045 and p=0.001, respectively), rs4290270 with depressive and anxiety traits (p=0.040 and p=0.025, respectively) and rs4570625 with aggressive traits (p=0.011). In abstinent subjects rs1843809 genotype was associated with traits of social anxiety (p=0.003). Only association between rs1843809 and the BDHI score (p=0.001) and associations between GTAA haplotype and Zung Anxiety Scale and BDHI score (p=0.001 and p<0.001, respectively), in currently dependent patients remained significant after applying the Bonferroni's correction. Our findings support a potential role of TPH2 in alcohol dependence. TPH2 genetic variability may be also associated with anxiety and aggression traits in alcohol dependent subjects. PMID:26232682

  2. Demographic variability and density-dependent dynamics of a free-ranging rhesus macaque population

    PubMed Central

    Hernández-Pacheco, Raisa; Rawlins, Richard G.; Kessler, Matthew J.; Williams, Lawrence E.; Ruiz-Maldonado, Tagrid M.; González-Martínez, Janis; Ruiz-Lambides, Angelina V.; Sabat, Alberto M.

    2014-01-01

    Density-dependence is hypothesized as the major mechanism of population regulation. However, the lack of long-term demographic data has hampered the use of density-dependent models in nonhuman primates. In this study, we make use of the long-term demographic data from Cayo Santiago’s rhesus macaques to parameterize and analyze both a density-independent and a density-dependent population matrix model, and compare their projections with the observed population changes. We also employ a retrospective analysis to determine how variance in vital rates, and covariance among them, contributed to the observed variation in long-term fitness across different levels of population density. The population exhibited negative density-dependence in fertility and the model incorporating this relationship accounted for 98% of the observed population dynamics. Variation in survival and fertility of sexually active individuals contributed the most to the variation in long-term fitness, while vital rates displaying high temporal variability exhibited lower sensitivities. Our findings are novel in describing density-dependent dynamics in a provisioned primate population, and in suggesting that selection is acting to lower the variance in the population growth rate by minimizing the variation in adult survival at high density. Because density-dependent mechanisms may become stronger in wild primate populations due to increasing habitat loss and food scarcity, our study demonstrates it is important to incorporate variation in population size, as well as demographic variability into population viability analyses for a better understanding of the mechanisms regulating the growth of primate populations. PMID:23847126

  3. Dependence among complex random variables as a fuel cell condition indicator

    NASA Astrophysics Data System (ADS)

    Mileva Boshkoska, Biljana; Boškoski, Pavle; Debenjak, Andrej; Juričić, Đani

    2015-06-01

    As various faults alter the PEM fuel cell impedance characteristic over a broad frequency range, the electrochemical impedance spectroscopy is frequently employed for the purpose of condition monitoring. The proposed methodology treats the impedance components among different frequencies as dependent complex random variables. The information about fuel cell condition is incorporated into the dependence structure of these complex random variables. This dependence is described through the corresponding joint cumulative density function by employing copula functions. The benefits of such an approach are threefold: (i) the estimation of the joint cumulative density function requires only several measurements of a fuel cell in a fault-free condition, (ii) the procedure is computationally efficient, and (iii) the output of the copula function is directly used as an overall unit-free condition indicator. The approach was evaluated on a kW-range PEM fuel cell stack subjected to water management faults of various severities. The results show that the ci corresponds with the severity of the induced faults.

  4. Stochasticity and determinism: how density-independent and density-dependent processes affect population variability.

    PubMed

    Ohlberger, Jan; Rogers, Lauren A; Stenseth, Nils Chr

    2014-01-01

    A persistent debate in population ecology concerns the relative importance of environmental stochasticity and density dependence in determining variability in adult year-class strength, which contributes to future reproduction as well as potential yield in exploited populations. Apart from the strength of the processes, the timing of density regulation may affect how stochastic variation, for instance through climate, translates into changes in adult abundance. In this study, we develop a life-cycle model for the population dynamics of a large marine fish population, Northeast Arctic cod, to disentangle the effects of density-independent and density-dependent processes on early life-stages, and to quantify the strength of compensatory density dependence in the population. The model incorporates information from scientific surveys and commercial harvest, and dynamically links multiple effects of intrinsic and extrinsic factors on all life-stages, from eggs to spawners. Using a state-space approach we account for observation error and stochasticity in the population dynamics. Our findings highlight the importance of density-dependent survival in juveniles, indicating that this period of the life cycle largely determines the compensatory capacity of the population. Density regulation at the juvenile life-stage dampens the impact of stochastic processes operating earlier in life such as environmental impacts on the production of eggs and climate-dependent survival of larvae. The timing of stochastic versus regulatory processes thus plays a crucial role in determining variability in adult abundance. Quantifying the contribution of environmental stochasticity and compensatory mechanisms in determining population abundance is essential for assessing population responses to climate change and exploitation by humans. PMID:24893001

  5. Major histocompatibility complex harbors widespread genotypic variability of non-additive risk of rheumatoid arthritis including epistasis

    PubMed Central

    Wei, Wen-Hua; Bowes, John; Plant, Darren; Viatte, Sebastien; Yarwood, Annie; Massey, Jonathan; Worthington, Jane; Eyre, Stephen

    2016-01-01

    Genotypic variability based genome-wide association studies (vGWASs) can identify potentially interacting loci without prior knowledge of the interacting factors. We report a two-stage approach to make vGWAS applicable to diseases: firstly using a mixed model approach to partition dichotomous phenotypes into additive risk and non-additive environmental residuals on the liability scale and secondly using the Levene’s (Brown-Forsythe) test to assess equality of the residual variances across genotype groups per marker. We found widespread significant (P < 2.5e-05) vGWAS signals within the major histocompatibility complex (MHC) across all three study cohorts of rheumatoid arthritis. We further identified 10 epistatic interactions between the vGWAS signals independent of the MHC additive effects, each with a weak effect but jointly explained 1.9% of phenotypic variance. PTPN22 was also identified in the discovery cohort but replicated in only one independent cohort. Combining the three cohorts boosted power of vGWAS and additionally identified TYK2 and ANKRD55. Both PTPN22 and TYK2 had evidence of interactions reported elsewhere. We conclude that vGWAS can help discover interacting loci for complex diseases but require large samples to find additional signals. PMID:27109064

  6. Analysis of accelerated failure time data with dependent censoring using auxiliary variables via nonparametric multiple imputation.

    PubMed

    Hsu, Chiu-Hsieh; Taylor, Jeremy M G; Hu, Chengcheng

    2015-08-30

    We consider the situation of estimating the marginal survival distribution from censored data subject to dependent censoring using auxiliary variables. We had previously developed a nonparametric multiple imputation approach. The method used two working proportional hazards (PH) models, one for the event times and the other for the censoring times, to define a nearest neighbor imputing risk set. This risk set was then used to impute failure times for censored observations. Here, we adapt the method to the situation where the event and censoring times follow accelerated failure time models and propose to use the Buckley-James estimator as the two working models. Besides studying the performances of the proposed method, we also compare the proposed method with two popular methods for handling dependent censoring through the use of auxiliary variables, inverse probability of censoring weighted and parametric multiple imputation methods, to shed light on the use of them. In a simulation study with time-independent auxiliary variables, we show that all approaches can reduce bias due to dependent censoring. The proposed method is robust to misspecification of either one of the two working models and their link function. This indicates that a working proportional hazards model is preferred because it is more cumbersome to fit an accelerated failure time model. In contrast, the inverse probability of censoring weighted method is not robust to misspecification of the link function of the censoring time model. The parametric imputation methods rely on the specification of the event time model. The approaches are applied to a prostate cancer dataset.

  7. Variability in Ozone in the Tropical Tropopause Region from the 1998-2000 SHADOZ (Southern Hemisphere ADditional OZonesondes) Data

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Witte, J. C.; Oltmans, S. J.; Schmidlin, F. J.

    2002-01-01

    The first view of stratospheric and tropospheric ozone variability in the southern hemisphere tropics is provided by a 3-year, 10-site record of ozone soundings from the Southern Hemisphere ADditional OZonesondes (SHADOZ) network. Observations covering 1998-2000 were made over Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. Taking the TTL (tropical tropopause layer) as the region between 12 and 17 km, we examine ozone variability in this region on a week-to-week and seasonal basis. The TTL layer is lower in September-October-November than in March-April-May, when ozone is a minimum at most SHADOZ stations. A zonal wave-one pattern is apparent in column-integrated TTL ozone because ozone mixing ratios are greater over the Atlantic and adjacent continents than over the Pacific and eastern Indian Ocean. The wave-one persists all year with varying magnitude and appears to be due to general circulation - with subsidence over the Atlantic and frequent deep convection over the Pacific and Indian Ocean. The variability of deep convection - most prominent at Java, Fiji, Samoa and Natal - is explored in time-vs-altitude ozone curtains. Stratospheric incursions into the troposphere are most prominent in soundings at Irene and Reunion Island.

  8. Variability in Ozone in the Tropical Tropopause Region from the 1998-2000 SHADOZ (Southern Hemisphere ADditional OZonesondes) Data

    NASA Astrophysics Data System (ADS)

    Thompson, A. M.; Witte, J. C.; Oltmans, S. J.; Schmidlin, F. J.

    2002-05-01

    The first view of stratospheric and tropospheric ozone variability in the southern hemisphere tropics is provided by a 3-year, 10-site record of ozone soundings from the Southern Hemisphere ADditional OZonesondes (SHADOZ) network: (http://code916.gsfc.nasa.gov/Data_services/shadoz). Observations covering 1998-2000 were made over Ascension Island; Nairobi, Kenya; Irene, South Africa; Réunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristóbal, Galapagos; Natal, Brazil. Taking the TTL (tropical tropopause layer) as the region between 12 and 17 km, we examine ozone variability in this region on a week-to-week and seasonal basis. The TTL layer is lower in September-October-November than in March-April-May, when ozone is a minimum at most SHADOZ stations. A zonal wave-one pattern is apparent in column-integrated TTL ozone because ozone mixing ratios are greater over the Atlantic and adjacent continents than over the Pacific and eastern Indian Ocean. The wave-one persists all year with varying magnitude and appears to be due to general circulation - with subsidence over the Atlantic and frequent deep convection over the Pacific and Indian Ocean. The variability of deep convection - most prominent at Java, Fiji, Samoa and Natal - is explored in time-vs-altitude ozone curtains. Stratospheric incursions into the troposphere are most prominent in soundings at Irene and Réunion Island.

  9. Memory effects, two color percolation, and the temperature dependence of Mott variable-range hopping

    NASA Astrophysics Data System (ADS)

    Agam, Oded; Aleiner, Igor L.

    2014-06-01

    There are three basic processes that determine hopping transport: (a) hopping between normally empty sites (i.e., having exponentially small occupation numbers at equilibrium), (b) hopping between normally occupied sites, and (c) transitions between normally occupied and unoccupied sites. In conventional theories all these processes are considered Markovian and the correlations of occupation numbers of different sites are believed to be small (i.e., not exponential in temperature). We show that, contrary to this belief, memory effects suppress the processes of type (c) and manifest themselves in a subleading exponential temperature dependence of the variable-range hopping conductivity. This temperature dependence originates from the property that sites of type (a) and (b) form two independent resistor networks that are weakly coupled to each other by processes of type (c). This leads to a two-color percolation problem which we solve in the critical region.

  10. Productivity depends more on the rate than the frequency of N addition in a temperate grassland.

    PubMed

    Zhang, Yunhai; Feng, Jinchao; Isbell, Forest; Lü, Xiaotao; Han, Xingguo

    2015-07-28

    Nitrogen (N) is a key limiting resource for aboveground net primary productivity (ANPP) in diverse terrestrial ecosystems. The relative roles of the rate and frequency (additions yr(-1)) of N application in stimulating ANPP at both the community- and species-levels are largely unknown. By independently manipulating the rate and frequency of N input, with nine rates (from 0 to 50 g N m(-2) year(-1)) crossed with two frequencies (twice year(-1) or monthly) in a temperate steppe of northern China across 2008-2013, we found that N addition increased community ANPP, and had positive, negative, or neutral effects for individual species. There were similar ANPP responses at the community- or species-level when a particular annual amount of N was added either twice year(-1) or monthly. The community ANPP was less sensitive to soil ammonium at lower frequency of N addition. ANPP responses to N addition were positively correlated with annual precipitation. Our results suggest that, over a five-year period, there will be similar ANPP responses to a given annual N input that occurs either frequently in small amounts, as from N deposition, or that occur infrequently in larger amounts, as from application of N fertilizers.

  11. On the nature of motor planning variables during arm pointing movement: Compositeness and speed dependence.

    PubMed

    Vu, Van Hoan; Isableu, Brice; Berret, Bastien

    2016-07-22

    The purpose of this study was to investigate the nature of the variables and rules underlying the planning of unrestrained 3D arm reaching. To identify whether the brain uses kinematic, dynamic and energetic values in an isolated manner or combines them in a flexible way, we examined the effects of speed variations upon the chosen arm trajectories during free arm movements. Within the optimal control framework, we uncovered which (possibly composite) optimality criterion underlays at best the empirical data. Fifteen participants were asked to perform free-endpoint reaching movements from a specific arm configuration at slow, normal and fast speeds. Experimental results revealed that prominent features of observed motor behaviors were significantly speed-dependent, such as the chosen reach endpoint and the final arm posture. Nevertheless, participants exhibited different arm trajectories and various degrees of speed dependence of their reaching behavior. These inter-individual differences were addressed using a numerical inverse optimal control methodology. Simulation results revealed that a weighted combination of kinematic, energetic and dynamic cost functions was required to account for all the critical features of the participants' behavior. Furthermore, no evidence for the existence of a speed-dependent tuning of these weights was found, thereby suggesting subject-specific but speed-invariant weightings of kinematic, energetic and dynamic variables during the motor planning process of free arm movements. This suggested that the inter-individual difference of arm trajectories and speed dependence was not only due to anthropometric singularities but also to critical differences in the composition of the subjective cost function. PMID:27132233

  12. Southern Hemisphere Additional Ozonesondes (SHADOZ) 1998-2000 tropical ozone climatology 2. Tropospheric variability and the zonal wave-one

    NASA Astrophysics Data System (ADS)

    Thompson, Anne M.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Schmidlin, Francis J.; Logan, Jennifer A.; Fujiwara, Masatomo; Kirchhoff, Volker W. J. H.; Posny, FrançOise; Coetzee, Gert J. R.; Hoegger, Bruno; Kawakami, Shuji; Ogawa, Toshihiro; Fortuin, J. P. F.; Kelder, H. M.

    2003-01-01

    The first view of stratospheric and tropospheric ozone variability in the Southern Hemisphere tropics is provided by a 3-year record of ozone soundings from the Southern Hemisphere Additional Ozonesondes (SHADOZ) network (http://croc.gsfc.nasa.gov/shadoz). Observations covering 1998-2000 were made over Ascension Island, Nairobi (Kenya), Irene (South Africa), Réunion Island, Watukosek (Java), Fiji, Tahiti, American Samoa, San Cristóbal (Galapagos), and Natal (Brazil). Total, stratospheric, and tropospheric column ozone amounts usually peak between August and November. Other features are a persistent zonal wave-one pattern in total column ozone and signatures of the quasi-biennial oscillation (QBO) in stratospheric ozone. The wave-one is due to a greater concentration of free tropospheric ozone over the tropical Atlantic than the Pacific and appears to be associated with tropical general circulation and seasonal pollution from biomass burning. Tropospheric ozone over the Indian and Pacific Oceans displays influences of the waning 1997-1998 El Niño, seasonal convection, and pollution transport from Africa. The most distinctive feature of SHADOZ tropospheric ozone is variability in the data, e.g., a factor of 3 in column amount at 8 of 10 stations. Seasonal and monthly means may not be robust quantities because statistics are frequently not Gaussian even at sites that are always in tropical air. Models and satellite retrievals should be evaluated on their capability for reproducing tropospheric variability and fine structure. A 1999-2000 ozone record from Paramaribo, Surinam (6°N, 55°W) (also in SHADOZ) shows a marked contrast to southern tropical ozone because Surinam is often north of the Intertropical Convergence Zone (ITCZ). A more representative tropospheric ozone climatology for models and satellite retrievals requires additional Northern Hemisphere tropical data.

  13. Dependence of interface roughness and diffuseness of Cu-Co electrodeposited multilayers on electrochemical additives

    NASA Astrophysics Data System (ADS)

    Merkourakis, Spyridon; Hÿtch, Martin J.; Chassaing, Elisabeth; Walls, Michael G.; Leprince-Wang, Yamin

    2003-09-01

    We examine the effect of two organic additives, sds and saccharin, and also the effect of the solution pH on the interface properties of Cu/Co nanolayers, produced by pulsed electrodeposition from a single aqueous bath. Quantitative Fresnel fringe transmission electron microscopy is applied to cross-sectional samples of the layers. The widths of their respective interfaces as well as the widths of individual Cu and Co layers are determined via comparison with computer simulations. These initial results are further numerically treated to yield information about the separate contributions of interdiffusion and roughness to total interface widths. Conclusions on the behavior of these organic additives are considered in the light of the giant magnetoresistance properties of the multilayers, as reported in previous work.

  14. Timing and Variability of Galactose Metabolic Gene Activation Depend on the Rate of Environmental Change

    PubMed Central

    Ma, Bo; Ott, William; Josić, Krešimir; Bennett, Matthew R.

    2015-01-01

    Modulation of gene network activity allows cells to respond to changes in environmental conditions. For example, the galactose utilization network in Saccharomyces cerevisiae is activated by the presence of galactose but repressed by glucose. If both sugars are present, the yeast will first metabolize glucose, depleting it from the extracellular environment. Upon depletion of glucose, the genes encoding galactose metabolic proteins will activate. Here, we show that the rate at which glucose levels are depleted determines the timing and variability of galactose gene activation. Paradoxically, we find that Gal1p, an enzyme needed for galactose metabolism, accumulates more quickly if glucose is depleted slowly rather than taken away quickly. Furthermore, the variability of induction times in individual cells depends non-monotonically on the rate of glucose depletion and exhibits a minimum at intermediate depletion rates. Our mathematical modeling suggests that the dynamics of the metabolic transition from glucose to galactose are responsible for the variability in galactose gene activation. These findings demonstrate that environmental dynamics can determine the phenotypic outcome at both the single-cell and population levels. PMID:26200924

  15. Delay-dependent resilient-robust stabilisation of uncertain networked control systems with variable sampling intervals

    NASA Astrophysics Data System (ADS)

    Yang, Feisheng; Zhang, Huaguang; Liu, Zhenwei; Li, Ranran

    2014-03-01

    This work is concerned with the robust resilient control problem for uncertain networked control systems (NCSs) with variable sampling intervals, variant-induced delays and possible data dropouts, which is seldom considered in current literature. It is mainly based on the continuous time-varying-delay system approach. Followed by the nominal case, delay-dependent resilient robust stabilising conditions for the closed-loop NCS against controller gain variations are derived by employing a novel Lyapunov-Krasovskii functional which makes good use of the information of both lower and upper bounds on the varying input delay, and the upper bound on the variable sampling interval as well. A feasible solution of the obtained criterion formulated as linear matrix inequalities can be gotten. A tighter bounding technique is presented for acquiring the time derivative of the functional so as to utilise many more useful elements, meanwhile neither slack variable nor correlated augmented item is introduced to reduce overall computational burden. Two examples are given to show the effectiveness of the proposed method.

  16. Cytotoxic Effects of Temozolomide and Radiation are Additive- and Schedule-Dependent

    SciTech Connect

    Chalmers, Anthony J.; Ruff, Elliot M.; Martindale, Christine; Lovegrove, Nadia; Short, Susan C.

    2009-12-01

    Purpose: Despite aggressive therapy comprising radical radiation and temozolomide (TMZ) chemotherapy, the prognosis for patients with glioblastoma multiforme (GBM) remains poor, particularly if tumors express O{sup 6}-methylguanine-DNA-methyltransferase (MGMT). The interactions between radiation and TMZ remain unclear and have important implications for scheduling and for developing strategies to improve outcomes. Methods and Materials: Factors determining the effects of combination therapy on clonogenic survival, cell-cycle checkpoint signaling and DNA repair were investigated in four human glioma cell lines (T98G, U373-MG, UVW, U87-MG). Results: Combining TMZ and radiation yielded additive cytotoxicity, but only when TMZ was delivered 72 h before radiation. Radiosensitization was not observed. TMZ induced G2/M cell-cycle arrest at 48-72 h, coincident with phosphorylation of Chk1 and Chk2. Additive G2/M arrest and Chk1/Chk2 phosphorylation was only observed when TMZ preceded radiation by 72 h. The ataxia-telangiectasia mutated (ATM) inhibitor KU-55933 increased radiation sensitivity and delayed repair of radiation-induced DNA breaks, but did not influence TMZ effects. The multiple kinase inhibitor caffeine enhanced the cytotoxicity of chemoradiation and exacerbated DNA damage. Conclusions: TMZ is not a radiosensitizing agent but yields additive cytotoxicity in combination with radiation. Our data indicate that TMZ treatment should commence at least 3 days before radiation to achieve maximum benefit. Activation of G2/M checkpoint signaling by TMZ and radiation has a cytoprotective effect that can be overcome by dual inhibition of ATM and ATR. More specific inhibition of checkpoint signaling will be required to increase treatment efficacy without exacerbating toxicity.

  17. Reproductive stage-dependent effects of additional cryoprotectant agents for the cryopreservation of stallion germ cells.

    PubMed

    Jung, Heejun; Kim, Namyoung; Yoon, Minjung

    2016-10-01

    The main objective of this study was to evaluate the efficacy of an additional cryoprotectant in 10% dimethyl sulfoxide (DMSO) on cryopreserving germ cells from stallions at different reproductive stages. Testicular samples were obtained from pre-pubertal (1-1.5 yr, n=6) and post-pubertal (3-7 yr, n=5) stallions. Germ cells were isolated using a two-enzyme digestion procedure and cryopreserved in minimal essential medium alpha containing 10% fetal bovine serum and 10% DMSO with or without addition of trehalose (50, 100, or 200mM) or polyethylene glycol (PEG, 2.5, 5, or 10%). Viability, cell population, and viable population were assessed after 1 and 3 months of cryopreservation. The viable UTF1-positive population of pre-pubertal stallion germ cells was also measured using immunocytochemistry after 1 and 3 months of cryopreservation. As expected, the viability, cell population, and viable cell population were significantly reduced after 1 and 3 months of cryopreservation. At the pre-pubertal stage, the addition of trehalose or PEG to 10% DMSO did not show any effect on the viability, cell population, viable cell population, or viable UTF1-positive germ cells at either 1 or 3 months after cryopreservation. However, at the post-pubertal stage, the viable population was significantly higher in germ cells that were cryopreserved with 5% or 10% PEG, than in the cells cryopreserved with 10% DMSO only. In conclusion, PEG at 5% or 10% added to 10% DMSO serves as an optimal cryoprotectant agent for the cryopreservation of germ cells from post-pubertal stallions. PMID:27546795

  18. Variability for Categorical Variables

    ERIC Educational Resources Information Center

    Kader, Gary D.; Perry, Mike

    2007-01-01

    Introductory statistics textbooks rarely discuss the concept of variability for a categorical variable and thus, in this case, do not provide a measure of variability. The impression is thus given that there is no measurement of variability for a categorical variable. A measure of variability depends on the concept of variability. Research has…

  19. Ionic strength-dependent changes in tentacular ion exchangers with variable ligand density. I. Structural properties.

    PubMed

    Bhambure, Rahul; Gillespie, Christopher M; Phillips, Michael; Graalfs, Heiner; Lenhoff, Abraham M

    2016-09-01

    The ligand density critically affects the performance of ion-exchange resins in such measures as the adsorption capacity and transport characteristics. However, for tentacular and other polymer-modified exchangers, the mechanistic basis of the effect of ligand density on performance is not yet fully understood. In this study we map the ionic strength-dependent structural changes in tentacular cation exchangers with variable ligand densities as the basis for subsequent investigation of effects on functional properties. Inverse size-exclusion chromatography (ISEC), scanning electron microscopy (SEM) and small-angle x-ray scattering (SAXS) were used to assess the effect of ionic strength on the pore size and intraparticle architecture of resin variants with different ligand densities. Comparison of ISEC and cryo-SEM results shows a considerable reduction in average pore size with increasing ligand density; these methods also confirm an increase of average pore size at higher ionic strengths. SAXS analysis of ionic strength-dependent conformational changes in the grafted polyelectrolyte layer shows a characteristic ionomer peak at values of the scattering vector q (0.1-0.2Å(-1)) that depend on the ligand density and the ionic strength of the solution. This peak attribution reflects nanoscale changes in the structure of the grafted polyelectrolyte chains that can in turn be responsible for observed pore-size changes in the resins. Finally, salt breakthrough experiments confirm a stronger Donnan exclusion effect on pore accessibility for small ions in the high ligand density variant. PMID:27544749

  20. THE GJ1214 SUPER-EARTH SYSTEM: STELLAR VARIABILITY, NEW TRANSITS, AND A SEARCH FOR ADDITIONAL PLANETS

    SciTech Connect

    Berta, Zachory K.; Charbonneau, David; Bean, Jacob; Irwin, Jonathan; Burke, Christopher J.; Desert, Jean-Michel; Nutzman, Philip; Falco, Emilio E.

    2011-07-20

    The super-Earth GJ1214b transits a nearby M dwarf that exhibits a 1% intrinsic variability in the near-infrared. Here, we analyze new observations to refine the physical properties of both the star and planet. We present three years of out-of-transit photometric monitoring of the stellar host GJ1214 from the MEarth Observatory and find the rotation period to be long, most likely an integer multiple of 53 days, suggesting low levels of magnetic activity and an old age for the system. We show that such variability will not pose significant problems to ongoing studies of the planet's atmosphere with transmission spectroscopy. We analyze two high-precision transit light curves from ESO's Very Large Telescope (VLT) along with seven others from the MEarth and Fred Lawrence Whipple Observatory 1.2 m telescopes, finding physical parameters for the planet that are consistent with previous work. The VLT light curves show tentative evidence for spot occultations during transit. Using two years of MEarth light curves, we place limits on additional transiting planets around GJ1214 with periods out to the habitable zone of the system. We also improve upon the previous photographic V-band estimate for the star, finding V = 14.71 {+-} 0.03.

  1. Vectran Fiber Time-Dependent Behavior and Additional Static Loading Properties

    NASA Technical Reports Server (NTRS)

    Fette, Russell B.; Sovinski, Marjorie F.

    2004-01-01

    Vectran HS appears from literature and testing to date to be an ideal upgrade from Kevlar braided cords for many long-term, static-loading applications such as tie-downs on solar arrays. Vectran is a liquid crystalline polymer and exhibits excellent tensile properties. The material has been touted as a zero creep product. Testing discussed in this report does not support this statement, though the creep is on the order of four times slower than with similar Kevlar 49 products. Previous work with Kevlar and new analysis of Vectran testing has led to a simple predictive model for Vectran at ambient conditions. The mean coefficient of thermal expansion (negative in this case) is similar to Kevlar 49, but is not linear. A positive transition in the curve occurs near 100 C. Out-gassing tests show that the material performs well within parameters for most space flight applications. Vectran also offers increased abrasion resistance, minimal moisture regain, and similar UV degradation. The effects of material construction appear to have a dramatic effect in stress relaxation for braided Vectran. To achieve the improved relaxation rate, upgrades must also examine alternate construction or preconditioning methods. This report recommends Vectran HS as a greatly improved replacement material for applications where time-dependent relaxation is a major factor.

  2. Priming effect in agricultural and forest soils depending on glucose level and N addition

    NASA Astrophysics Data System (ADS)

    Splettstoesser, Thomas; Kumar, Amit; Sun, Yue

    2015-04-01

    Growing plants continuously release easily available organic compounds into the rhizosphere. By their interactions with soil microbial biomass (MB) these compounds result in changes of organic matter turnover rates. The understanding of this priming effect (PE) is important for the estimation of climate change impacts on different land use systems. In order to investigate the PE, we conducted a soil incubation experiment under laboratory conditions with two loamy soils: one under cropland and the second under a deciduous forest near Göttingen. 13C and 14C Glucose were added in four levels reaching from 10% to 300% of MB-C. Furthermore two nitrogen levels were established in order to investigate the effects of fertilization on PE. During the whole experiment CO2 release was monitored by trapping in a NaOH solution. Nitrogen mineralization rate, activity of enzymes, and composition of MB were analyzed at the start, after one day, after one week and at the end of the experiment. The results on priming effects induced in agricultural and forest soils depending on N and glucose levels will be presented.

  3. Uncovering hidden variance: pair-wise SNP analysis accounts for additional variance in nicotine dependence

    PubMed Central

    Culverhouse, Robert C.; Saccone, Nancy L.; Stitzel, Jerry A.; Wang, Jen C.; Steinbach, Joseph H.; Goate, Alison M.; Schwantes-An, Tae-Hwi; Grucza, Richard A.; Stevens, Victoria L.; Bierut, Laura J.

    2010-01-01

    Results from genome-wide association studies of complex traits account for only a modest proportion of the trait variance predicted to be due to genetics. We hypothesize that joint analysis of polymorphisms may account for more variance. We evaluated this hypothesis on a case–control smoking phenotype by examining pairs of nicotinic receptor single-nucleotide polymorphisms (SNPs) using the Restricted Partition Method (RPM) on data from the Collaborative Genetic Study of Nicotine Dependence (COGEND). We found evidence of joint effects that increase explained variance. Four signals identified in COGEND were testable in independent American Cancer Society (ACS) data, and three of the four signals replicated. Our results highlight two important lessons: joint effects that increase the explained variance are not limited to loci displaying substantial main effects, and joint effects need not display a significant interaction term in a logistic regression model. These results suggest that the joint analyses of variants may indeed account for part of the genetic variance left unexplained by single SNP analyses. Methodologies that limit analyses of joint effects to variants that demonstrate association in single SNP analyses, or require a significant interaction term, will likely miss important joint effects. PMID:21079997

  4. Time-dependent sleep stage transition model based on heart rate variability.

    PubMed

    Takeda, Toki; Mizuno, Osamu; Tanaka, Tomohiro

    2015-01-01

    A new model is proposed to automatically classify sleep stages using heart rate variability (HRV). The generative model, based on the characteristics that the distribution and the transition probabilities of sleep stages depend on the elapsed time from the beginning of sleep, infers the sleep stage with a Gibbs sampler. Experiments were conducted using a public data set consisting of 45 healthy subjects and the model's classification accuracy was evaluated for three sleep stages: wake state, rapid eye movement (REM) sleep, and non-REM sleep. Experimental results demonstrated that the model provides more accurate sleep stage classification than conventional (naive Bayes and Support Vector Machine) models that do not take the above characteristics into account. Our study contributes to improve the quality of sleep monitoring in the daily life using easy-to-wear HRV sensors. PMID:26736763

  5. Investigation of stochastic reactor noise models--A one-variable space-time-dependent model

    SciTech Connect

    Mesko, L.; Kozma, R.

    1984-09-01

    Using the Markovian description of stochastic processes, the fluctuations in pressurized water reactor cores (for example, temperature and bubble population fluctuations) are modeled. The model includes one-dimensional space and time dependence. Fluctuations are described with the help of a single stochastic variable N(z,t). Generally this approach is not satisfactory in practical problems, but in this way spatial effects can be investigated by a simple model. For this case, connections between moments of N(z,t) are derived. These moments are calculated both for transient and steady-state processes. Introducing spectral density functions in frequency and wave-number domains, a condition is given for the validity of the point model approach.

  6. X-point position dependence of edge intrinsic toroidal rotation on the Tokamak à Configuration Variable

    SciTech Connect

    Stoltzfus-Dueck, T.; Karpushov, A. N.; Sauter, O.; Duval, B. P.; Labit, B.; Reimerdes, H.; Vijvers, W. A. J.; Camenen, Y.

    2015-05-15

    Recent theoretical work predicts intrinsic toroidal rotation in the tokamak edge to depend strongly on the normalized major radial position of the X-point. With this motivation, we conducted a series of Ohmic L-mode shots on the Tokamak à Configuration Variable, moving the X-point from the inboard to the outboard edge of the last closed flux surface in both lower and upper single null configurations. The edge toroidal rotation evolved from strongly co-current for an inboard X-point to either vanishing or counter-current for an outboard X-point, in agreement with the theoretical expectations. The whole rotation profile shifted roughly rigidly with the edge rotation, resulting in variation of the peak core rotation by more than a factor of two. Core rotation reversals had little effect on the edge rotation. Edge rotation was slightly more counter-current for unfavorable than favorable ∇B drift discharges.

  7. Characterizing Non-Linear Dependencies Among Pairs of Clinical Variables and Imaging Data

    PubMed Central

    Caban, Jesus J.; Bagci, Ulas; Mehari, Alem; Alam, Shoaib; Fontana, Joseph R.; Kato, Gregory J.; Mollura, Daniel J.

    2012-01-01

    Advances in computer-aided diagnosis (CAD) systems have shown the benefits of using computer-based techniques to obtain quantitative image measurements of the extent of a particular disease. Such measurements provide more accurate information that can be used to better study the associations between anatomical changes and clinical findings. Unfortunately, even with the use of quantitative image features, the correlations between anatomical changes and clinical findings are often not apparent and definite conclusions are difficult to reach. This paper uses nonparametric exploration techniques to demonstrate that even when the associations between two-variables seems weak, advanced properties of the associations can be studied and used to better understand the relationships between individual measurements. This paper uses quantitative imaging findings and clinical measurements of 85 patients with pulmonary fibrosis to demonstrate the advantages of non-linear dependency analysis. Results show that even when the correlation coefficients between imaging and clinical findings seem small, statistical measurements such as the maximum asymmetry score (MAS) and maximum edge value (MEV) can be used to better understand the hidden associations between the variables. PMID:23366482

  8. Elevated intraindividual variability in methamphetamine dependence is associated with poorer everyday functioning.

    PubMed

    Morgan, Erin E; Doyle, Katie L; Minassian, Arpi; Henry, Brook L; Perry, William; Marcotte, Thomas D; Woods, Steven Paul; Grant, Igor

    2014-12-15

    Methamphetamine (MA) dependence is associated with executive dysfunction, but no studies have evaluated MA-related elevations in neurocognitive intraindividual variability (IIV), an expression of cognitive dyscontrol linked to poor daily functioning in populations with frontal systems injury. We examined IIV during a vigilance task in a well-characterized sample of 35 MA-dependent (MA+) and 55 non-MA using comparison participants (MA-) as part of a larger neuropsychological battery that included self-report and performance-based measures of everyday functioning. A mixed model ANOVA was conducted while controlling for covariates, including factors that differed between the groups (e.g., education) and those with conceptual relevance to IIV: mean reaction time, global cognitive performance, and HIV-infection (which was comparable across groups; p=0.32). This analysis revealed significantly elevated IIV among MA+ relative to MA- individuals that was comparable in magnitude across all trial blocks of the vigilance task. Within the MA group, elevated IIV was associated with executive dysfunction, psychomotor slowing, and recency of MA use, as well as poorer automobile driving simulator performance, worse laboratory-based functional skills, and more cognitive complaints. MA-users are vulnerable to IIV elevation, likely due to cognitive dyscontrol, which may increase their risk of real-world problems.

  9. Elevated intraindividual variability in methamphetamine dependence is associated with poorer everyday functioning

    PubMed Central

    Morgan, Erin E.; Doyle, Katie L.; Minassian, Arpi; Henry, Brook; Perry, William; Marcotte, Thomas D.; Woods, Steven Paul; Grant, Igor

    2014-01-01

    Methamphetamine (MA) dependence is associated with executive dysfunction, but no studies have evaluated MA-related elevations in neurocognitive intraindividual variability (IIV), an expression of cognitive dyscontrol linked to poor daily functioning in populations with frontal systems injury. We examined IIV during a vigilance task in a well-characterized sample of 35 MA-dependent (MA+) and 55 non-MA using comparison participants (MA−) as part of a larger neuropsychological battery that included self-report and performance-based measures of everyday functioning. A mixed model ANOVA was conducted while controlling for covariates, including factors that differed between the groups (e.g., education) and those with conceptual relevance to IIV: mean reaction time, global cognitive performance, and HIV-infection (which was comparable across groups; p = .32). This analysis revealed significantly elevated IIV among MA+ relative to MA− individuals that was comparable in magnitude across all trial blocks of the vigilance task. Within the MA group, elevated IIV was associated with executive dysfunction, psychomotor slowing, and recency of MA use, as well as poorer automobile driving simulator performance, worse laboratory-based functional skills, and more cognitive complaints. MA-users are vulnerable to IIV elevation, likely due to cognitive dyscontrol, which may increase their risk of real-world problems. PMID:25081313

  10. Field Variable Associations With Scratch Orientation-Dependence of UHMWPE Wear: A Finite Element Analysis

    PubMed Central

    Paul, Matthew C.; Glennon, Liam P.; Baer, Thomas E.; Brown, Thomas D.

    2008-01-01

    Background Scratches on the metal bearing surface of metal-on-polyethylene total joint replacements have been found to appreciably accelerate abrasive/adhesive wear of polyethylene, and constitute a source of the considerable variability of wear rate seen within clinical cohorts. Scratch orientation with respect to the local direction of relative surface sliding is presumably a factor affecting instantaneous debris liberation during articulation. Method of Approach A three-dimensional local finite element model was developed of orientation-specific polyethylene articulation with a scratched metal counterface, to explore continuum-level stress/strain parameters potentially correlating with the orientation dependence of scratch wear in a corresponding physical experiment. Results Computed maximum stress values exceeded the yield strength of ultra-high molecular weight polyethylene (UHMWPE) for all scratch orientations, but did not vary appreciably among scratch orientations. Two continuum-level parameters judged most consistent overall with the direction dependence of experimental wear were: (1) cumulative compressive total normal strain in the direction of loading, and (2) maximum instantaneous compressive total normal strain transverse to the sliding direction. Conclusions Such stress/strain metrics could be useful in global computational models of wear acceleration, as surrogates to incorporate anisotropy of local metal surface roughening. PMID:19045548

  11. Some Statistical Strategies for DAE-seq Data Analysis: Variable Selection and Modeling Dependencies among Observations

    PubMed Central

    Rashid, Naim U.; Sun, Wei; Ibrahim, Joseph G.

    2014-01-01

    In DAE (DNA After Enrichment)-seq experiments, genomic regions related with certain biological processes are enriched/isolated by an assay and are then sequenced on a high-throughput sequencing platform to determine their genomic positions. Statistical analysis of DAE-seq data aims to detect genomic regions with significant aggregations of isolated DNA fragments (“enriched regions”) versus all the other regions (“background”). However, many confounding factors may influence DAE-seq signals. In addition, the signals in adjacent genomic regions may exhibit strong correlations, which invalidate the independence assumption employed by many existing methods. To mitigate these issues, we develop a novel Autoregressive Hidden Markov Model (AR-HMM) to account for covariates effects and violations of the independence assumption. We demonstrate that our AR-HMM leads to improved performance in identifying enriched regions in both simulated and real datasets, especially in those in epigenetic datasets with broader regions of DAE-seq signal enrichment. We also introduce a variable selection procedure in the context of the HMM/AR-HMM where the observations are not independent and the mean value of each state-specific emission distribution is modeled by some covariates. We study the theoretical properties of this variable selection procedure and demonstrate its efficacy in simulated and real DAE-seq data. In summary, we develop several practical approaches for DAE-seq data analysis that are also applicable to more general problems in statistics. PMID:24678134

  12. Variable Temperature Stress in the Nematode Caenorhabditis elegans (Maupas) and Its Implications for Sensitivity to an Additional Chemical Stressor.

    PubMed

    Cedergreen, Nina; Nørhave, Nils Jakob; Svendsen, Claus; Spurgeon, David J

    2016-01-01

    A wealth of studies has investigated how chemical sensitivity is affected by temperature, however, almost always under different constant rather than more realistic fluctuating regimes. Here we compared how the nematode Caenorhabditis elegans responds to copper at constant temperatures (8-24°C) and under fluctuation conditions of low (±4°C) and high (±8°C) amplitude (averages of 12, 16, 20°C and 16°C respectively). The DEBkiss model was used to interpret effects on energy budgets. Increasing constant temperature from 12-24°C reduced time to first egg, life-span and population growth rates consistent with temperature driven metabolic rate change. Responses at 8°C did not, however, accord with this pattern (including a deviation from the Temperature Size Rule), identifying a cold stress effect. High amplitude variation and low amplitude variation around a mean temperature of 12°C impacted reproduction and body size compared to nematodes kept at the matching average constant temperatures. Copper exposure affected reproduction, body size and life-span and consequently population growth. Sensitivity to copper (EC50 values), was similar at intermediate temperatures (12, 16, 20°C) and higher at 24°C and especially the innately stressful 8°C condition. Temperature variation did not increase copper sensitivity. Indeed under variable conditions including time at the stressful 8°C condition, sensitivity was reduced. DEBkiss identified increased maintenance costs and increased assimilation as possible mechanisms for cold and higher copper concentration effects. Model analysis of combined variable temperature effects, however, demonstrated no additional joint stressor response. Hence, concerns that exposure to temperature fluctuations may sensitise species to co-stressor effects seem unfounded in this case.

  13. Variable Temperature Stress in the Nematode Caenorhabditis elegans (Maupas) and Its Implications for Sensitivity to an Additional Chemical Stressor.

    PubMed

    Cedergreen, Nina; Nørhave, Nils Jakob; Svendsen, Claus; Spurgeon, David J

    2016-01-01

    A wealth of studies has investigated how chemical sensitivity is affected by temperature, however, almost always under different constant rather than more realistic fluctuating regimes. Here we compared how the nematode Caenorhabditis elegans responds to copper at constant temperatures (8-24°C) and under fluctuation conditions of low (±4°C) and high (±8°C) amplitude (averages of 12, 16, 20°C and 16°C respectively). The DEBkiss model was used to interpret effects on energy budgets. Increasing constant temperature from 12-24°C reduced time to first egg, life-span and population growth rates consistent with temperature driven metabolic rate change. Responses at 8°C did not, however, accord with this pattern (including a deviation from the Temperature Size Rule), identifying a cold stress effect. High amplitude variation and low amplitude variation around a mean temperature of 12°C impacted reproduction and body size compared to nematodes kept at the matching average constant temperatures. Copper exposure affected reproduction, body size and life-span and consequently population growth. Sensitivity to copper (EC50 values), was similar at intermediate temperatures (12, 16, 20°C) and higher at 24°C and especially the innately stressful 8°C condition. Temperature variation did not increase copper sensitivity. Indeed under variable conditions including time at the stressful 8°C condition, sensitivity was reduced. DEBkiss identified increased maintenance costs and increased assimilation as possible mechanisms for cold and higher copper concentration effects. Model analysis of combined variable temperature effects, however, demonstrated no additional joint stressor response. Hence, concerns that exposure to temperature fluctuations may sensitise species to co-stressor effects seem unfounded in this case. PMID:26784453

  14. Variable Temperature Stress in the Nematode Caenorhabditis elegans (Maupas) and Its Implications for Sensitivity to an Additional Chemical Stressor

    PubMed Central

    Svendsen, Claus; Spurgeon, David J.

    2016-01-01

    A wealth of studies has investigated how chemical sensitivity is affected by temperature, however, almost always under different constant rather than more realistic fluctuating regimes. Here we compared how the nematode Caenorhabditis elegans responds to copper at constant temperatures (8–24°C) and under fluctuation conditions of low (±4°C) and high (±8°C) amplitude (averages of 12, 16, 20°C and 16°C respectively). The DEBkiss model was used to interpret effects on energy budgets. Increasing constant temperature from 12–24°C reduced time to first egg, life-span and population growth rates consistent with temperature driven metabolic rate change. Responses at 8°C did not, however, accord with this pattern (including a deviation from the Temperature Size Rule), identifying a cold stress effect. High amplitude variation and low amplitude variation around a mean temperature of 12°C impacted reproduction and body size compared to nematodes kept at the matching average constant temperatures. Copper exposure affected reproduction, body size and life-span and consequently population growth. Sensitivity to copper (EC50 values), was similar at intermediate temperatures (12, 16, 20°C) and higher at 24°C and especially the innately stressful 8°C condition. Temperature variation did not increase copper sensitivity. Indeed under variable conditions including time at the stressful 8°C condition, sensitivity was reduced. DEBkiss identified increased maintenance costs and increased assimilation as possible mechanisms for cold and higher copper concentration effects. Model analysis of combined variable temperature effects, however, demonstrated no additional joint stressor response. Hence, concerns that exposure to temperature fluctuations may sensitise species to co-stressor effects seem unfounded in this case. PMID:26784453

  15. Highly variable gastric emptying in patients with insulin dependent diabetes mellitus.

    PubMed Central

    Nowak, T V; Johnson, C P; Kalbfleisch, J H; Roza, A M; Wood, C M; Weisbruch, J P; Soergel, K H

    1995-01-01

    Some diabetic patients--particularly those with nausea and vomiting--frequently have evidence of delayed gastric emptying while other diabetic patients may in fact exhibit accelerated gastric emptying. Whether the presence or absence of symptoms of upper gastrointestinal dysfunction correlated with objective measures of gastric emptying in insulin dependent diabetic subjects was investigated. Twenty one insulin dependent diabetic patients underwent a solid phase gastric emptying scintiscan using in vivo labelled chicken liver. Thirteen patients had symptoms suggestive of gastrointestinal dysfunction (nausea, vomiting, early satiety, or constipation), while eight patients had no gastrointestinal symptoms. Eleven patients had orthostatic hypotension. All patients had been diabetic since childhood or adolescence. As a group, the diabetic patients showed a half time (T50) of gastric emptying (mean (SD) 150.0 min (163.7) that was not significantly different from that of 12 healthy control subjects (148.1 min (62.4)). Those diabetic patients without gastrointestinal symptoms and without orthostatic hypotension, however, showed a gastric emptying half time (70.1 min (41.6)) that was significantly faster than that of the control subjects. Conversely, those diabetic patients with nausea, vomiting, and early satiety (or early satiety alone) showed T50 values that were significantly greater than those of the diabetic patients without these symptoms. No correlation was found between the T50 value and the duration of diabetes, the fasting blood glucose at the time of study, or the respiratory variation in heart rate (E:I ratio). These observations indicate that highly variable rates of gastric emptying occur in insulin dependent diabetic patients, and that accelerated gastric emptying may occur in diabetic patients who have no symptoms of gastrointestinal dysfunction. PMID:7672674

  16. Post-lumpectomy CT-guided tumor bed delineation for breast boost and partial breast irradiation: Can additional pre- and postoperative imaging reduce interobserver variability?

    PubMed Central

    DEN HARTOGH, MARISKA D.; PHILIPPENS, MARIELLE E.P.; VAN DAM, IRIS E.; KLEYNEN, CATHARINA E.; TERSTEEG, ROBBERT J.H.A.; KOTTE, ALEXIS N.T.J.; VAN VULPEN, MARCO; VAN ASSELEN, BRAM; VAN DEN BONGARD, DESIRÉE H.J.G.

    2015-01-01

    For breast boost radiotherapy or accelerated partial breast irradiation, the tumor bed (TB) is delineated by the radiation oncologist on a planning computed tomography (CT) scan. The aim of the present study was to investigate whether the interobserver variability (IOV) of the TB delineation is reduced by providing the radiation oncologist with additional magnetic resonance imaging (MRI) or CT scans. A total of 14 T1-T2 breast cancer patients underwent a standard planning CT in the supine treatment position following lumpectomy, as well as additional pre- and postoperative imaging in the same position. Post-lumpectomy TBs were independently delineated by four breast radiation oncologists on standard postoperative CT and on CT registered to an additional imaging modality. The additional imaging modalities used were postoperative MRI, preoperative contrast-enhanced (CE)-CT and preoperative CE-MRI. A cavity visualization score (CVS) was assigned to each standard postoperative CT by each observer. In addition, the conformity index (CI), volume and distance between centers of mass (dCOM) of the TB delineations were calculated. On CT, the median CI was 0.57, with a median volume of 22 cm3 and dCOM of 5.1 mm. The addition of postoperative MRI increased the median TB volume significantly to 28 cm3 (P<0.001), while the CI (P=0.176) and dCOM (P=0.110) were not affected. The addition of preoperative CT or MRI increased the TB volume to 26 and 25 cm3, respectively (both P<0.001), while the CI increased to 0.58 and 0.59 (both P<0.001) and the dCOM decreased to 4.7 mm (P=0.004) and 4.6 mm (P=0.001), respectively. In patients with CVS≤3, the median CI was 0.40 on CT, which was significantly increased by all additional imaging modalities, up to 0.52, and was accompanied by a median volume increase up to 6 cm3. In conclusion, the addition of postoperative MRI, preoperative CE-CT or preoperative CE-MRI did not result in a considerable reduction in the IOV in postoperative CT

  17. Comments on 'Improved delay-dependent stability criteria for continuous systems with two additive time-varying delay components'

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, K.; Venkatachalam, V.; Ray, G.

    2015-07-01

    In this write-up, comments on the omission of few important inequality conditions (or constraints) in the LMI optimization problem stated as delay-dependent stability criterion for a class of linear systems with two additive time-varying state-delays in Cheng et al. (2014) is reported. The omission paves way to incorrectness of the published result. The consequence of the omission, and the revised result are presented in the sequel.

  18. Using XMM-Newton to study the energy-dependent variability of H 1743-322 during its 2014 outburst

    NASA Astrophysics Data System (ADS)

    Stiele, H.; Yu, W.

    2016-08-01

    Black hole transients evolve during bright outbursts, showing distinct changes in their spectral and variability properties. These changes are interpreted as evidence for changes in the accretion flow and in the X-ray-emitting regions. We obtained an anticipated XMM-Newton Target of Opportunity observation of H 1743-322 during its outburst in 2014 September. Based on data from eight outbursts observed in the last 10 yr, we expected to catch the start of the hard-to-soft state transition. The fact that neither the general shape of the observed power density spectrum nor the characteristic frequency shows an energy dependence implies that the source remained in the low-hard state at the time of our observation near outburst peak. The spectral properties agree with the source being in the low-hard state, and a Swift/XRT monitoring of the outburst revealed that H 1743-322 stayed in the low-hard state during the entire outburst (known as a `failed outburst'). Here we derive the averaged QPO waveform and obtain phase-resolved spectra. A comparison of the phase-resolved spectra with the phase-averaged energy spectrum reveals spectral pivoting. We compare variability on long and short time-scales using covariance spectra and find that the covariance ratio does not show an increase towards lower energies. In other binaries an increase has been found. There are two possible explanations: either the absence of additional disc variability on longer time-scales is related to the high inclination of H 1743-322 compared with other black hole X-ray binaries, or it is the reason why we observe H 1743-322 during a failed outburst. More data on failed outbursts and on high-inclination sources will be needed in order to investigate these two possibilities further.

  19. The severity of retinal pathology in homozygous Crb1rd8/rd8 mice is dependent on additional genetic factors.

    PubMed

    Luhmann, Ulrich F O; Carvalho, Livia S; Holthaus, Sophia-Martha Kleine; Cowing, Jill A; Greenaway, Simon; Chu, Colin J; Herrmann, Philipp; Smith, Alexander J; Munro, Peter M G; Potter, Paul; Bainbridge, James W B; Ali, Robin R

    2015-01-01

    Understanding phenotype-genotype correlations in retinal degeneration is a major challenge. Mutations in CRB1 lead to a spectrum of autosomal recessive retinal dystrophies with variable phenotypes suggesting the influence of modifying factors. To establish the contribution of the genetic background to phenotypic variability associated with the Crb1(rd8/rd8) mutation, we compared the retinal pathology of Crb1(rd8/rd8)/J inbred mice with that of two Crb1(rd8/rd8) lines backcrossed with C57BL/6JOlaHsd mice. Topical endoscopic fundal imaging and scanning laser ophthalmoscopy fundus images of all three Crb1(rd8/rd8) lines showed a significant increase in the number of inferior retinal lesions that was strikingly variable between the lines. Optical coherence tomography, semithin, ultrastructural morphology and assessment of inflammatory and vascular marker by immunohistochemistry and quantitative reverse transcriptase-polymerase chain reaction revealed that the lesions were associated with photoreceptor death, Müller and microglia activation and telangiectasia-like vascular remodelling-features that were stable in the inbred, variable in the second, but virtually absent in the third Crb1(rd8/rd8) line, even at 12 months of age. This suggests that the Crb1(rd8/rd8) mutation is necessary, but not sufficient for the development of these degenerative features. By whole-genome SNP analysis of the genotype-phenotype correlation, a candidate region on chromosome 15 was identified. This may carry one or more genetic modifiers for the manifestation of the retinal pathology associated with mutations in Crb1. This study also provides insight into the nature of the retinal vascular lesions that likely represent a clinical correlate for the formation of retinal telangiectasia or Coats-like vasculopathy in patients with CRB1 mutations that are thought to depend on such genetic modifiers.

  20. The Southern Hemisphere Additional Ozonesondes (SHADOZ) 1998-2002 Tropical Ozone Climatology. 3; Instrumentation and Station-to-Station Variability

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Witte, Jacqueline C.; Smit, Herman G. J.; Oltmans, Samuel J.; Johnson, Bryan J.; Kirchhoff, Volker W. J. H.; Schmidlin, Francis J.

    2004-01-01

    Abstract: Since 1998 the Southern Hemisphere ADditional OZonesondes (SHADOZ) project has collected more than 2000 ozone profiles from a dozen tropical and subtropical sites using balloon-borne electrochemical concentration cell (ECC) ozonesondes. The data (with accompanying pressure-temperature-humidity soundings) are archived. Analysis of ozonesonde imprecision within the SHADOZ dataset revealed that variations in ozonesonde technique could lead to station-to-station biases in the measurements. In this paper imprecisions and accuracy in the SHADOZ dataset are examined in light of new data. When SHADOZ total ozone column amounts are compared to version 8 TOMS (2004 release), discrepancies between sonde and satellite datasets decline 1-2 percentage points on average, compared to version 7 TOMS. Variability among stations is evaluated using total ozone normalized to TOMS and results of laboratory tests on ozonesondes (JOSE-2O00, Julich Ozonesonde Intercomparison Experiment). Ozone deviations from a standard instrument in the JOSE flight simulation chamber resemble those of SHADOZ station data relative to a SHADOZ-defined climatological reference. Certain systematic variations in SHADOZ ozone profiles are accounted for by differences in solution composition, data processing and instrument (manufacturer). Instrument bias leads to a greater ozone measurement above 25 km over Nairobi and to lower total column ozone at three Pacific sites compared to other SHADOZ stations at 0-20 deg.S.

  1. Mapping and decomposing scale-dependent soil moisture variability within an Inner Bluegrass landscape

    NASA Astrophysics Data System (ADS)

    Landrum, Carla Jill

    There is a shared desire among public and private sectors to produce more reliable predictions, accurate mapping, and appropriate scaling of soil moisture and associated parameters across landscapes. A discrepancy often exists between the scale at which soil hydrologic properties are measured and the scale at which they are modeled for management purposes. Moreover, little is known about the relative importance of hydrologic modeling parameters as soil moisture fluctuates with time. More research is needed to establish which observation scales in space and time are optimal for managing soil moisture variation over large spatial extents and how these scales are affected by fluctuations in soil moisture content with time. This research fuses high resolution geoelectric and light detection and ranging (LiDAR) as auxiliary measures to support sparse direct soil sampling over a 40 hectare inner BluegrassKentucky (USA) landscape. A Veris 3100 was used to measure shallow and deep apparent electrical conductivity (aEC) in tandem with soil moisture sampling on three separate dates with ascending soil moisture contents ranging from plant wilting point to near field capacity. Terrain attributes were produced from 2010 LiDAR ground returns collected at ≤1 m nominal pulse spacing. Exploratory statistics revealed several variables best associate with soil moisture, including terrain features (slope, profile curvature, and elevation), soil physical and chemical properties (calcium, cation exchange capacity, organic matter, clay and sand) and aEC for each date. Multivariate geostatistics, time stability analyses, and spatial regression were performed to characterize scale-dependent soil moisture patterns in space with time to determine which soil-terrain parameters influence soil moisture distribution. Results showed that soil moisture variation was time stable across the landscape and primarily associated with long-range (˜250 m) soil physicochemical properties. When the soils

  2. Three Ingredients for Improved Global Aftershock Forecasts: Tectonic Region, Time-Dependent Catalog Incompleteness, and Inter-Sequence Variability

    NASA Astrophysics Data System (ADS)

    Page, M. T.; Hardebeck, J.; Felzer, K. R.; Michael, A. J.; van der Elst, N.

    2015-12-01

    Following a large earthquake, seismic hazard can be orders of magnitude higher than the long-term average as a result of aftershock triggering. Due to this heightened hazard, there is a demand from emergency managers and the public for rapid, authoritative, and reliable aftershock forecasts. In the past, USGS aftershock forecasts following large, global earthquakes have been released on an ad-hoc basis with inconsistent methods, and in some cases, aftershock parameters adapted from California. To remedy this, we are currently developing an automated aftershock product that will generate more accurate forecasts based on the Reasenberg and Jones (Science, 1989) method. To better capture spatial variations in aftershock productivity and decay, we estimate regional aftershock parameters for sequences within the Garcia et al. (BSSA, 2012) tectonic regions. We find that regional variations for mean aftershock productivity exceed a factor of 10. The Reasenberg and Jones method combines modified-Omori aftershock decay, Utsu productivity scaling, and the Gutenberg-Richter magnitude distribution. We additionally account for a time-dependent magnitude of completeness following large events in the catalog. We generalize the Helmstetter et al. (2005) equation for short-term aftershock incompleteness and solve for incompleteness levels in the global NEIC catalog following large mainshocks. In addition to estimating average sequence parameters within regions, we quantify the inter-sequence parameter variability. This allows for a more complete quantification of the forecast uncertainties and Bayesian updating of the forecast as sequence-specific information becomes available.

  3. Time-dependence in relativistic collisionless shocks: theory of the variable

    SciTech Connect

    Spitkovsky, A

    2004-02-05

    We describe results from time-dependent numerical modeling of the collisionless reverse shock terminating the pulsar wind in the Crab Nebula. We treat the upstream relativistic wind as composed of ions and electron-positron plasma embedded in a toroidal magnetic field, flowing radially outward from the pulsar in a sector around the rotational equator. The relativistic cyclotron instability of the ion gyrational orbit downstream of the leading shock in the electron-positron pairs launches outward propagating magnetosonic waves. Because of the fresh supply of ions crossing the shock, this time-dependent process achieves a limit-cycle, in which the waves are launched with periodicity on the order of the ion Larmor time. Compressions in the magnetic field and pair density associated with these waves, as well as their propagation speed, semi-quantitatively reproduce the behavior of the wisp and ring features described in recent observations obtained using the Hubble Space Telescope and the Chandra X-Ray Observatory. By selecting the parameters of the ion orbits to fit the spatial separation of the wisps, we predict the period of time variability of the wisps that is consistent with the data. When coupled with a mechanism for non-thermal acceleration of the pairs, the compressions in the magnetic field and plasma density associated with the optical wisp structure naturally account for the location of X-ray features in the Crab. We also discuss the origin of the high energy ions and their acceleration in the equatorial current sheet of the pulsar wind.

  4. Characteristics of heart rate variability in alcohol-dependent subjects and nondependent chronic alcohol users.

    PubMed

    Karpyak, Victor M; Romanowicz, Magdalena; Schmidt, John E; Lewis, Kriste A; Bostwick, John M

    2014-01-01

    Heart rate variability (HRV) is an objective and sensitive measure of integrated physiological functioning reflective of heart rhythm responsivity to internal and external demands. Reduced HRV is associated with vulnerability to stress and deterioration of medical and/or psychiatric conditions, while increased HRV is associated with a favorable treatment response and recovery from various medical and/or psychiatric conditions. Our previous review found that acute alcohol consumption caused decreased parasympathetic and increased sympathetic HRV effects in both nonalcoholic and chronic alcohol users. This review investigates the effects of chronic alcohol consumption on HRV in alcohol-dependent subjects and nondependent users. MEDLINE, Scopus, and PubMed were searched for human experimental and clinical trials that measured the effects of chronic alcohol use on HRV. Only publications that included a description of their study designs and clearly stated methodologies for data collections, and outcome measures were reviewed. We have reviewed a total of 24 articles. In nondependent users, low dose (approximating the recommended daily amount of 1 standard drink in women and 2 in men) use is associated with increased HRV parameters compared to those who drink less frequently or abstain altogether. A further increase in consumption is associated with decreased HRV compared to both abstainers and more moderate drinkers. HRV changes during withdrawal generally follow the same negative direction but are more complex and less understood. In dependent subjects, an improvement in HRV was seen following abstinence but remained reduced compared to nonalcoholic controls. This review demonstrates that HRV changes associated with chronic use follow a J-shaped curve. It supports recommendations that limit daily alcohol intake to no more than 2 drinks for men and 1 drink for women. Future studies should investigate HRV as a biomarker of alcoholism development and treatment response as

  5. The Dependence of Cloud Particle Size on Non-Aerosol-Loading Related Variables

    SciTech Connect

    Shao, H.; Liu, G.

    2005-03-18

    An enhanced concentration of aerosol may increase the number of cloud drops by providing more cloud condensation nuclei (CCN), which in turn results in a higher cloud albedo at a constant cloud liquid water path. This process is often referred to as the aerosol indirect effect (AIE). Many in situ and remote sensing observations support this hypothesis (Ramanathan et al. 2001). However, satellite observed relations between aerosol concentration and cloud drop size are not always in agreement with the AIE. Based on global analysis of cloud effective radius (r{sub e}) and aerosol number concentration (N{sub a}) derived from satellite data, Sekiguchi et al. (2003) found that the correlations between the two variables can be either negative, or positive, or none, depending on the location of the clouds. They discovered that significantly negative r{sub e} - N{sub a} correlation can only be identified along coastal regions of the continents where abundant continental aerosols inflow from land, whereas Feingold et al. (2001) found that the response of r{sub e} to aerosol loading is the greatest in the region where aerosol optical depth ({tau}{sub a}) is the smallest. The reason for the discrepancy is likely due to the variations in cloud macroscopic properties such as geometrical thickness (Brenguier et al. 2003). Since r{sub e} is modified not only by aerosol but also by cloud geometrical thickness (H), the correlation between re and {tau}{sub a} actually reflects both the aerosol indirect effect and dependence of H. Therefore, discussing AIE based on the r{sub e}-{tau}{sub a} correlation without taking into account variations in cloud geometrical thickness may be misleading. This paper is motivated to extract aerosols' effect from overall effects using the independent measurements of cloud geometrical thickness, {tau}{sub a} and r{sub e}.

  6. A classification of substance-dependent men on temperament and severity variables.

    PubMed

    Henderson, Melinda J; Galen, Luke W

    2003-06-01

    This study examined the validity of classifying substance abusers based on temperament and dependence severity, and expanded the scope of typology differences to proximal determinants of use (e.g., expectancies, motives). Patients were interviewed about substance use, depression, and family history of alcohol and drug abuse. Self-report instruments measuring temperament, expectancies, and motives were completed. Participants were 147 male veterans admitted to inpatient substance abuse treatment at a U.S. Department of Veterans Affairs medical center. Cluster analysis identified four types of users with two high substance problem severity and two low substance problem severity groups. Two, high problem severity, early onset groups differed only on the cluster variable of negative affectivity (NA), but showed differences on antisocial personality characteristics, hypochondriasis, and coping motives for alcohol. The two low problem severity groups were distinguished by age of onset and positive affectivity (PA). The late onset, low PA group had a higher incidence of depression, a greater tendency to use substances in solitary contexts, and lower enhancement motives for alcohol compared to the early onset, high PA cluster. The four-cluster solution yielded more distinctions on external criteria than the two-cluster solution. Such temperament variation within both high and low severity substance abusers may be important for treatment planning.

  7. Being selective at the plate: processing dependence between perceptual variables relates to hitting goals and performance.

    PubMed

    Gray, Rob

    2013-08-01

    Performance of a skill that involves acting on a goal object (e.g., a ball to be hit) can influence one's judgment of the size and speed of that object. The present study examined how these action-specific effects are affected when the goal of the actor is varied and they are free to choose between alternative actions. In Experiment 1, expert baseball players were asked to perform three different directional hitting tasks in a batting simulation and make interleaved perceptual judgments about three ball parameters (speed, plate crossing location, and size). Perceived ball size was largest (and perceived speed was slowest) when the ball crossing location was optimal for the particular hitting task the batter was performing (e.g., an "outside" pitch for opposite-field hitting). The magnitude of processing dependency between variables (speed vs. location and size vs. location) was positively correlated with batting performance. In Experiment 2, the action-specific effects observed in Experiment 1 were mimicked by systematically changing the ball diameter in the simulation as a function of plate crossing location. The number of swing initiations was greater when ball size was larger, and batters were more successful in the hitting task for which the larger pitches were optimal (e.g., greater number of pull hits than opposite-field hits when "inside" pitches were larger). These findings suggest attentional accentuation of goal-relevant targets underlies action-related changes in perception and are consistent with an action selection role for these effects.

  8. Radial dependence of line profile variability in seven O9-B0.5 stars

    NASA Astrophysics Data System (ADS)

    Martins, F.; Marcolino, W.; Hillier, D. J.; Donati, J.-F.; Bouret, J.-C.

    2015-02-01

    Context. Massive stars show a variety of spectral variabilities: discrete absorption components in UV P-Cygni profiles, optical line profile variability, X-ray variability, and radial velocity modulations. Aims: Our goal is to study the spectral variability of single OB stars to better understand the relation between photospheric and wind variability. For that, we rely on high spectral resolution and on high signal-to-noise ratio optical spectra collected with the spectrograph NARVAL on the Télescope Bernard Lyot at Pic du Midi. Methods: We investigated the variability of twelve spectral lines by means of the temporal variance spectrum. The selected lines probe the radial structure of the atmosphere from the photosphere to the outer wind. We also performed a spectroscopic analysis with atmosphere models to derive the stellar and wind properties and to constrain the formation region of the selected lines. Results: We show that variability is observed in the wind lines of all bright giants and supergiants on a daily timescale. Lines formed in the photosphere are sometimes variable, sometimes not. The dwarf stars do not show any sign of variability. If variability is observed on a daily timescale, it can also (but not always) be observed on hourly timescales, albeit with lower amplitude. There is a very clear correlation between amplitude of the variability and fraction of the line formed in the wind. Strong anti-correlations between the different parts of the temporal variance spectrum are observed. Conclusions: Our results indicate that variability is stronger in lines formed in the wind. A link between photospheric and wind variability is not obvious from our study, since wind variability is observed regardless of the level of photospheric variability. Different photospheric lines also show different degrees of variability. Appendices are available in electronic form at http://www.aanda.org

  9. Time-Dependent Prediction and Evaluation of Variable Importance Using SuperLearning in High Dimensional Clinical Data

    PubMed Central

    Hubbard, Alan; Munoz, Ivan Diaz; Decker, Anna; Holcomb, John B; Schreiber, Martin A; Bulger, Eileen M; Brasel, Karen J; Fox, Erin E; del Junco, Deborah J; Wade, Charles E; Rahbar, Mohammad H; Cotton, Bryan A; Phelan, Herb A; Myers, John G; Alarcon, Louis H; Muskat, Peter; Cohen, Mitchell J

    2013-01-01

    Background Prediction of outcome after injury is fraught with uncertainty and statistically beset by misspecified models. Single-time point regression only gives prediction and inference at one time, of dubious value for continuous prediction of ongoing bleeding. New statistical, machine learning techniques such as SuperLearner exist to make superior prediction at iterative time-points while also evaluating the changing relative importance of each measured variable on an outcome. This then can provide continuously changing prediction of outcome and evaluation of which clinical variables likely drive a particular outcome. Methods PROMMTT data was evaluated utilizing both naïve (standard stepwise logistic regression) and SuperLearner techniques to develop a time-dependent prediction of future mortality, within discrete time intervals. We avoided both under- and over-fitting using cross-validation to select an optimal combination of predictors among candidate predictors/machine learning algorithms. SuperLearner was also used to produce interval-specific robust measures of variable importance measures (VIM resulting in an ordered list of variables, by time-point) that have the strongest impact on future mortality. Results 980 patients had complete clinical and outcome data and were included in the analysis. The prediction of ongoing transfusion with SuperLearner was superior to the naïve approach for all time intervals (correlations of cross-validated predictions with the outcome were 0.819, 0.789, 0.792 for time intervals 30–90, 90–180, 180–360, >360 minutes. The estimated VIM of mortality also changed significantly at each time point Conclusions The SuperLeaner technique for prediction of outcome from a complex dynamic multivariate dataset is superior at each time interval to standard models. Additionally, the SuperLearner VIM at each time point provides insight into the time-specific drivers of future outcome, patient trajectory and targets for clinical

  10. An Empirical, Nonparametric Simulator for Multivariate Random Variables with Differing Marginal Densities and Nonlinear Dependence with Hydroclimatic Applications.

    PubMed

    Lall, Upmanu; Devineni, Naresh; Kaheil, Yasir

    2016-01-01

    Multivariate simulations of a set of random variables are often needed for risk analysis. Given a historical data set, the goal is to develop simulations that reproduce the dependence structure in that data set so that the risk of potentially correlated factors can be evaluated. A nonparametric, copula-based simulation approach is developed and exemplified. It can be applied to multiple variables or to spatial fields with arbitrary dependence structures and marginal densities. The nonparametric simulator uses logspline density estimation in the univariate setting, together with a sampling strategy to reproduce dependence across variables or spatial instances, through a nonparametric numerical approximation of the underlying copula function. The multivariate data vectors are assumed to be independent and identically distributed. A synthetic example is provided to illustrate the method, followed by an application to the risk of livestock losses in Mongolia. PMID:26177987

  11. Time-of-day dependence of isokinetic leg strength and associated interday variability.

    PubMed Central

    Wyse, J P; Mercer, T H; Gleeson, N P

    1994-01-01

    The purpose of this study was to assess the interday variability and time-of-day effects on selected isokinetic leg strength indices. Nine adult collegiate sportsmen (mean(s.e.) age 19.6(0.5) years; mean(s.e.) height 1.81(0.02) m; mean(s.e.) body mass 76.5(3.1) kg) completed a series of nine test sessions, organized so that each subject was tested three times within a day (08.00-09.00 hours; 13.00-14.00 hours; 18.00-19.30 hours), on three occasions, each separated by a minimum of 7 days. Gravity-corrected indices of extension peak torque (EPT), flexion peak torque (FPT), and the peak torque ratio (PTR), at contraction velocities of 1.05 rad s-1 and 3.14 rad s-1, were calculated for each subject using an isokinetic dynamometer. Two-way repeated measures analysis of variance of coefficient of variation (V%) scores revealed no significant differences in performance variability across within-subject factors of time-of-day and performance index (P > 0.05). Overall mean(s.e.) V% for scores across experimental conditions were 3.97(0.72)% at 1.05 rad s-1 and 5.98(1.23)% at 3.14 rad s-1, suggesting that similar levels of measurement error occur between 08.00-19.30 hours. One-way repeated measures analysis of variance of absolute strength indices (EPT, FPT and PTR) revealed that significantly higher scores were achieved during session 3 (18.00-19.30 hours), with mean(s.e.) values of 249.1(40.0) N m, 149.0(32.3) N m, 59.5(5.0)% at 1.05 rad s-1, and 172.1(38.7) N m, 121.3(27.7) N m, 71.1(6.2)% at 3.14 rad s-1, respectively (P < 0.05). This finding appears to be consistent with current knowledge about time-of-day effects on the assessment of muscular strength. Thus for stable and maximal values to be obtained during isokinetic leg testing, the use of multiple-trial protocols is recommended, with testing occurring as close to 18.00-19.30 hours as possible. In addition, the observed significant time-of-day effect suggests that appropriate comparison of maximal isokinetic leg

  12. Being selective at the plate: processing dependence between perceptual variables relates to hitting goals and performance.

    PubMed

    Gray, Rob

    2013-08-01

    Performance of a skill that involves acting on a goal object (e.g., a ball to be hit) can influence one's judgment of the size and speed of that object. The present study examined how these action-specific effects are affected when the goal of the actor is varied and they are free to choose between alternative actions. In Experiment 1, expert baseball players were asked to perform three different directional hitting tasks in a batting simulation and make interleaved perceptual judgments about three ball parameters (speed, plate crossing location, and size). Perceived ball size was largest (and perceived speed was slowest) when the ball crossing location was optimal for the particular hitting task the batter was performing (e.g., an "outside" pitch for opposite-field hitting). The magnitude of processing dependency between variables (speed vs. location and size vs. location) was positively correlated with batting performance. In Experiment 2, the action-specific effects observed in Experiment 1 were mimicked by systematically changing the ball diameter in the simulation as a function of plate crossing location. The number of swing initiations was greater when ball size was larger, and batters were more successful in the hitting task for which the larger pitches were optimal (e.g., greater number of pull hits than opposite-field hits when "inside" pitches were larger). These findings suggest attentional accentuation of goal-relevant targets underlies action-related changes in perception and are consistent with an action selection role for these effects. PMID:23163787

  13. Variability of Mass Dependence of Auroral Acceleration Processes with Solar Activity

    NASA Technical Reports Server (NTRS)

    Ghielmetti, Arthur G.

    1997-01-01

    The objectives of this investigation are to improve understanding of the mass dependent variability of the auroral acceleration processes and so to clarify apparent discrepancies regarding the altitude and local time variations with solar cycle by investigating: (1) the global morphological relationships between auroral electric field structures and the related particle signatures under varying conditions of solar activity, and (2) the relationships between the electric field structures and particle signatures in selected events that are representative of the different conditions occurring during a solar cycle. The investigation is based in part on the Lockheed UFI data base of UpFlowing Ion (UFI) events in the 5OO eV to 16keV energy range and associated electrons in the energy range 7O eV to 24 keV. This data base was constructed from data acquired by the ion mass spectrometer on the S3-3 satellite in the altitude range of I to 1.3 Re. The launch of the POLAR spacecraft in early 1996 and successful operation of its TIMAS ion mass spectrometer has provided us with data from within the auroral acceleration regions during the current solar minimum. The perigee of POLAR is at about 1 Re, comparable to that of S3-3. The higher sensitivity and time resolution of TIMAS compared to the ion mass spectrometer on S3-3 together with its wider energy range, 15 eV to 33 keV, facilitate more detailed studies of upflowing ions.

  14. Characterization of Seasonally Dependent Emergent Vegetation Variables for Coastal Impact Models

    NASA Astrophysics Data System (ADS)

    Stellern, C.; Grossman, E.; Linneman, S. R.; Fuller, R.

    2015-12-01

    Emergent wetland vegetation has been shown to mitigate coastal inundation and erosion hazards by reducing wave energy through friction (Shepard et al., 2011), although its use in coastal protection planning is limited because predictive models require improved vegetation data. We isolated biophysical characteristics (biomass, stem density, rigidity, etc.) of plants using horizontal digital photographs (Side-On Photos) in conjunction with remote sensing and physical surveys. We studied the dominant salt-marsh species/assemblages in Port Susan Bay of Washington State, a vulnerable estuary that has experienced up to 1 kilometer of marsh retreat since the mid-1960s. We measured plant height, stem diameter, stem density (area available for flow) from fall to early spring (August 2014 through April 2015) using Side-On Photography and digital image processing techniques. Metrics from Side-On Photography were highly correlated to physical lab measurements. Vegetation rigidity was measured in-situ with a handheld digital scale with respect to measurement height and bending angle. Plant elasticity showed a strong correlation to stem diameter in two dominant bulrush species. We employed remote sensing supervised classifications techniques (Maximum-Likelihood and Decision Tree Classifiers) to hyperspectral imagery to map the spatial extent of vegetation assemblages with an overall accuracy of 86.7%. Combining these methods enabled us to extrapolate and validate vegetation characteristics across the study area and to estimate species-specific friction coefficients for input to cross-shore wave models. On-going studies include sensitivity analyses of wave models to seasonally-dependent vegetation parameters in the nearshore and ultimately wave impacts along the coast. By accounting for site-specific and spatiotemporal variability in vegetation data, we inform scientific understanding of the interactions of vegetation, waves, and sediment processes.

  15. Dependency of the Cusp Density Anomaly on the Variability of Forcing Inside and Outside the Cusp

    NASA Astrophysics Data System (ADS)

    Brinkman, D. G.; Walterscheid, R. L.; Clemmons, J. H.

    2014-12-01

    The Earth's magnetospheric cusp provides direct access of energetic particles to the thermosphere. These particles produce ionization and kinetic (particle) heating of the atmosphere. The increased ionization coupled with enhanced electric fields in the cusp produces increased Joule heating and ion drag forcing. These energy inputs largely determine the neutral density structure in the cusp region. Measurements by the CHAMP satellite (460-390- km altitude) have shown a region of strong enhanced density attributed to the combination of cusp particle and Joule heating. The Streak mission (325-123 km), on the other hand, observed a relative depletion in density in the cusp. While particle precipitation in the cusp is comparatively well constrained, the characteristics of the steady and fluctuating components of the electric field in the cusp are poorly constrained. Also, the significance of harder particle precipitation in areas adjacent to the cusp in particular at lower altitudes has not been addressed as it relates to the cusp density anomaly. We address the response of the cusp region to a range electrodynamical forcing with our high resolution two-dimensional time-dependent nonhydrostatic nonlinear dynamical model. We take advantage of our model's high resolution and focus on a more typical cusp width of 2 degrees in latitude. Earlier simulations have also shown a significant contribution from soft particle precipitation. We simulate the atmospheric response to a range of realizable magnitudes of the fluctuating and steady components of the electric field to examine the dependence of the magnitude of the cusp density anomaly on a large range of observed characteristics of the electrodynamical forcing and examine, in particular, the importance of particle heating relative to Joule heating. In addition we investigate the role of harder particle precipitation in areas adjacent to the cusp in determining the lower altitude cusp density and wind structure. We compare

  16. Three ingredients for Improved global aftershock forecasts: Tectonic region, time-dependent catalog incompleteness, and inter-sequence variability

    USGS Publications Warehouse

    Page, Morgan T.; Van Der Elst, Nicholas; Hardebeck, Jeanne L.; Felzer, Karen; Michael, Andrew J.

    2016-01-01

    Following a large earthquake, seismic hazard can be orders of magnitude higher than the long‐term average as a result of aftershock triggering. Because of this heightened hazard, emergency managers and the public demand rapid, authoritative, and reliable aftershock forecasts. In the past, U.S. Geological Survey (USGS) aftershock forecasts following large global earthquakes have been released on an ad hoc basis with inconsistent methods, and in some cases aftershock parameters adapted from California. To remedy this, the USGS is currently developing an automated aftershock product based on the Reasenberg and Jones (1989) method that will generate more accurate forecasts. To better capture spatial variations in aftershock productivity and decay, we estimate regional aftershock parameters for sequences within the García et al. (2012) tectonic regions. We find that regional variations for mean aftershock productivity reach almost a factor of 10. We also develop a method to account for the time‐dependent magnitude of completeness following large events in the catalog. In addition to estimating average sequence parameters within regions, we develop an inverse method to estimate the intersequence parameter variability. This allows for a more complete quantification of the forecast uncertainties and Bayesian updating of the forecast as sequence‐specific information becomes available.

  17. Template-dependent nucleotide addition in the reverse (3'-5') direction by Thg1-like protein.

    PubMed

    Kimura, Shoko; Suzuki, Tateki; Chen, Meirong; Kato, Koji; Yu, Jian; Nakamura, Akiyoshi; Tanaka, Isao; Yao, Min

    2016-03-01

    Thg1-like protein (TLP) catalyzes the addition of a nucleotide to the 5'-end of truncated transfer RNA (tRNA) species in a Watson-Crick template-dependent manner. The reaction proceeds in two steps: the activation of the 5'-end by adenosine 5'-triphosphate (ATP)/guanosine 5'-triphosphate (GTP), followed by nucleotide addition. Structural analyses of the TLP and its reaction intermediates have revealed the atomic detail of the template-dependent elongation reaction in the 3'-5' direction. The enzyme creates two substrate binding sites for the first- and second-step reactions in the vicinity of one reaction center consisting of two Mg(2+) ions, and the two reactions are executed at the same reaction center in a stepwise fashion. When the incoming nucleotide is bound to the second binding site with Watson-Crick hydrogen bonds, the 3'-OH of the incoming nucleotide and the 5'-triphosphate of the tRNA are moved to the reaction center where the first reaction has occurred. That the 3'-5' elongation enzyme performs this elaborate two-step reaction in one catalytic center suggests that these two reactions have been inseparable throughout the process of protein evolution. Although TLP and Thg1 have similar tetrameric organization, the tRNA binding mode of TLP is different from that of Thg1, a tRNA(His)-specific G-1 addition enzyme. Each tRNA(His) binds to three of the four Thg1 tetramer subunits, whereas in TLP, tRNA only binds to a dimer interface and the elongation reaction is terminated by measuring the accepter stem length through the flexible β-hairpin. Furthermore, mutational analyses show that tRNA(His) is bound to TLP in a similar manner as Thg1, thus indicating that TLP has a dual binding mode.

  18. Template-dependent nucleotide addition in the reverse (3′-5′) direction by Thg1-like protein

    PubMed Central

    Kimura, Shoko; Suzuki, Tateki; Chen, Meirong; Kato, Koji; Yu, Jian; Nakamura, Akiyoshi; Tanaka, Isao; Yao, Min

    2016-01-01

    Thg1-like protein (TLP) catalyzes the addition of a nucleotide to the 5′-end of truncated transfer RNA (tRNA) species in a Watson-Crick template–dependent manner. The reaction proceeds in two steps: the activation of the 5′-end by adenosine 5′-triphosphate (ATP)/guanosine 5′-triphosphate (GTP), followed by nucleotide addition. Structural analyses of the TLP and its reaction intermediates have revealed the atomic detail of the template-dependent elongation reaction in the 3′-5′ direction. The enzyme creates two substrate binding sites for the first- and second-step reactions in the vicinity of one reaction center consisting of two Mg2+ ions, and the two reactions are executed at the same reaction center in a stepwise fashion. When the incoming nucleotide is bound to the second binding site with Watson-Crick hydrogen bonds, the 3′-OH of the incoming nucleotide and the 5′-triphosphate of the tRNA are moved to the reaction center where the first reaction has occurred. That the 3′-5′ elongation enzyme performs this elaborate two-step reaction in one catalytic center suggests that these two reactions have been inseparable throughout the process of protein evolution. Although TLP and Thg1 have similar tetrameric organization, the tRNA binding mode of TLP is different from that of Thg1, a tRNAHis-specific G−1 addition enzyme. Each tRNAHis binds to three of the four Thg1 tetramer subunits, whereas in TLP, tRNA only binds to a dimer interface and the elongation reaction is terminated by measuring the accepter stem length through the flexible β-hairpin. Furthermore, mutational analyses show that tRNAHis is bound to TLP in a similar manner as Thg1, thus indicating that TLP has a dual binding mode. PMID:27051866

  19. The benefits of an additional worker are task-dependent: assessing low-back injury risks during prefabricated (panelized) wall construction.

    PubMed

    Kim, Sunwook; Nussbaum, Maury A; Jia, Bochen

    2012-09-01

    Team manual material handling is a common practice in residential construction where prefabricated building components (e.g., wall panels) are increasingly used. As part of a larger effort to enable proactive control of ergonomic exposures among workers handling panels, this study explored the effects of additional workers on injury risks during team-based panel erection tasks, specifically by quantifying how injury risks are affected by increasing the number of workers (by one, above the nominal or most common number). Twenty-four participants completed panel erection tasks with and without an additional worker under different panel mass and size conditions. Four risk assessment methods were employed that emphasized the low back. Though including an additional worker generally reduced injury risk across several panel masses and sizes, the magnitude of these benefits varied depending on the specific task and exhibited somewhat high variability within a given task. These results suggest that a simple, generalizable recommendation regarding team-based panel erection tasks is not warranted. Rather, a more systems-level approach accounting for both injury risk and productivity (a strength of panelized wall systems) should be undertaken.

  20. The Relationship of Field Dependent/Independent Cognitive Styles, Stimuli Variability and Time Factor on Student Achievement.

    ERIC Educational Resources Information Center

    Atang, Christopher I.

    The effects of black and white and color illustrations on student achievement were studied to investigate the relationships between cognitive styles and instructional design. Field dependence (FD) and field independence (FI) were chosen as the cognitive style variables. Subjects were 85 freshman students in the Iowa State University Psychology…

  1. The influence of non-solvent addition on the independent and dependent parameters in roller electrospinning of polyurethane.

    PubMed

    Cengiz-Callioglu, Funda; Jirsak, Oldrich; Dayik, Mehmet

    2013-07-01

    This paper discusses the effects of 1,1,2,2 tetrachlorethylen (TCE) non-solvent addition on the independent (electrical conductivity, dielectric constant, surface tension and the theological properties of the solution etc.) and dependent parameters (number of Taylor cones per square meter (NTC/m2), spinning performance for one Taylor cone (SP/TC), total spinning performance (SP), fiber properties such as diameter, diameter uniformity, non-fibrous area) in roller electrospinning of polyurethane (PU). The same process parameters (voltage, distance of the electrodes, humidity, etc.) were applied for all solutions during the spinning process. According to the results, the effect of TCE non-solvent concentration on the dielectric constant, surface tension, rheological properties of the solution and also spinning performance was important statistically. Beside these results, TCE non-solvent concentration effects quality of fiber and nano web structure. Generally high fiber density, low non-fibrous percentage and uniform nanofibers were obtained from fiber morphology analyses.

  2. Estimation of a partially linear additive model for data from an outcome-dependent sampling design with a continuous outcome.

    PubMed

    Tan, Ziwen; Qin, Guoyou; Zhou, Haibo

    2016-10-01

    Outcome-dependent sampling (ODS) designs have been well recognized as a cost-effective way to enhance study efficiency in both statistical literature and biomedical and epidemiologic studies. A partially linear additive model (PLAM) is widely applied in real problems because it allows for a flexible specification of the dependence of the response on some covariates in a linear fashion and other covariates in a nonlinear non-parametric fashion. Motivated by an epidemiological study investigating the effect of prenatal polychlorinated biphenyls exposure on children's intelligence quotient (IQ) at age 7 years, we propose a PLAM in this article to investigate a more flexible non-parametric inference on the relationships among the response and covariates under the ODS scheme. We propose the estimation method and establish the asymptotic properties of the proposed estimator. Simulation studies are conducted to show the improved efficiency of the proposed ODS estimator for PLAM compared with that from a traditional simple random sampling design with the same sample size. The data of the above-mentioned study is analyzed to illustrate the proposed method.

  3. Estimation of a partially linear additive model for data from an outcome-dependent sampling design with a continuous outcome.

    PubMed

    Tan, Ziwen; Qin, Guoyou; Zhou, Haibo

    2016-10-01

    Outcome-dependent sampling (ODS) designs have been well recognized as a cost-effective way to enhance study efficiency in both statistical literature and biomedical and epidemiologic studies. A partially linear additive model (PLAM) is widely applied in real problems because it allows for a flexible specification of the dependence of the response on some covariates in a linear fashion and other covariates in a nonlinear non-parametric fashion. Motivated by an epidemiological study investigating the effect of prenatal polychlorinated biphenyls exposure on children's intelligence quotient (IQ) at age 7 years, we propose a PLAM in this article to investigate a more flexible non-parametric inference on the relationships among the response and covariates under the ODS scheme. We propose the estimation method and establish the asymptotic properties of the proposed estimator. Simulation studies are conducted to show the improved efficiency of the proposed ODS estimator for PLAM compared with that from a traditional simple random sampling design with the same sample size. The data of the above-mentioned study is analyzed to illustrate the proposed method. PMID:27006375

  4. Age Dependent Variability in Gene Expression in Fischer 344 Rat Retina.

    EPA Science Inventory

    Recent evidence suggests older adults may be a sensitive population with regard to environmental exposure to toxic compounds. One source of this sensitivity could be an enhanced variability in response. Studies on phenotypic differences have suggested that variation in response d...

  5. A Better Lemon Squeezer? Maximum-Likelihood Regression with Beta-Distributed Dependent Variables

    ERIC Educational Resources Information Center

    Smithson, Michael; Verkuilen, Jay

    2006-01-01

    Uncorrectable skew and heteroscedasticity are among the "lemons" of psychological data, yet many important variables naturally exhibit these properties. For scales with a lower and upper bound, a suitable candidate for models is the beta distribution, which is very flexible and models skew quite well. The authors present maximum-likelihood…

  6. What determines the spatial variability of soil respiration and its temperature dependence (Q10) at catchment scale (Rur Catchment, Germany)?

    NASA Astrophysics Data System (ADS)

    Meyer, Nele; Welp, Gerhard; Amelung, Wulf

    2016-04-01

    Climate change is suspected to alter temperature, soil moisture, and nutrient inputs to the soil. These factors are supposed to strongly influence soil respiration. The degree by which respiration will respond to these changes is crucial for assessing future CO2 feedbacks to the atmosphere. We assume that the temperature sensitivity of soil respiration (Q10) differs spatially depending on land use, soil unit, and texture owing to their diverse properties of soil organic matter quantity and quality. We further hypothesize that the Q10 value is additionally regulated by soil moisture and nutrient status. On the basis of soil and land use maps we divided the Rur catchment (Western Germany, 2350 km²) into so called environmental soil classes (ESC) that combine each a unique combination of the factors land use, soil unit, and texture. We took nine samples from each of the 12 most common ESC's and incubated them at five temperatures (5-25°C), at four soil moisture levels (30-75% water holding capacity), and with an unfertilized and a fertilized treatment. So far, our results indicate that both soil respiration and the Q10 value are spatially highly variable with Q10 values ranging from 1 to 4. The Q10 value is altered by the level of soil moisture and decreases when soils are as moist as 75% water holding capacity. Fertilization has no effect on the Q10 value. Currently, we are processing the whole data-set to derive the effect of ESC's on the Q10 value. Recent data suggest that forest soils are more sensitive to warming than cropland soils.

  7. Proteomic Interaction Patterns between Human Cyclins, the Cyclin-Dependent Kinase Ortholog pUL97 and Additional Cytomegalovirus Proteins.

    PubMed

    Steingruber, Mirjam; Kraut, Alexandra; Socher, Eileen; Sticht, Heinrich; Reichel, Anna; Stamminger, Thomas; Amin, Bushra; Couté, Yohann; Hutterer, Corina; Marschall, Manfred

    2016-01-01

    The human cytomegalovirus (HCMV)-encoded cyclin-dependent kinase (CDK) ortholog pUL97 associates with human cyclin B1 and other types of cyclins. Here, the question was addressed whether cyclin interaction of pUL97 and additional viral proteins is detectable by mass spectrometry-based approaches. Proteomic data were validated by coimmunoprecipitation (CoIP), Western blot, in vitro kinase and bioinformatic analyses. Our findings suggest that: (i) pUL97 shows differential affinities to human cyclins; (ii) pUL97 inhibitor maribavir (MBV) disrupts the interaction with cyclin B1, but not with other cyclin types; (iii) cyclin H is identified as a new high-affinity interactor of pUL97 in HCMV-infected cells; (iv) even more viral phosphoproteins, including all known substrates of pUL97, are detectable in the cyclin-associated complexes; and (v) a first functional validation of pUL97-cyclin B1 interaction, analyzed by in vitro kinase assay, points to a cyclin-mediated modulation of pUL97 substrate preference. In addition, our bioinformatic analyses suggest individual, cyclin-specific binding interfaces for pUL97-cyclin interaction, which could explain the different strengths of interactions and the selective inhibitory effect of MBV on pUL97-cyclin B1 interaction. Combined, the detection of cyclin-associated proteins in HCMV-infected cells suggests a complex pattern of substrate phosphorylation and a role of cyclins in the fine-modulation of pUL97 activities.

  8. Proteomic Interaction Patterns between Human Cyclins, the Cyclin-Dependent Kinase Ortholog pUL97 and Additional Cytomegalovirus Proteins

    PubMed Central

    Steingruber, Mirjam; Kraut, Alexandra; Socher, Eileen; Sticht, Heinrich; Reichel, Anna; Stamminger, Thomas; Amin, Bushra; Couté, Yohann; Hutterer, Corina; Marschall, Manfred

    2016-01-01

    The human cytomegalovirus (HCMV)-encoded cyclin-dependent kinase (CDK) ortholog pUL97 associates with human cyclin B1 and other types of cyclins. Here, the question was addressed whether cyclin interaction of pUL97 and additional viral proteins is detectable by mass spectrometry-based approaches. Proteomic data were validated by coimmunoprecipitation (CoIP), Western blot, in vitro kinase and bioinformatic analyses. Our findings suggest that: (i) pUL97 shows differential affinities to human cyclins; (ii) pUL97 inhibitor maribavir (MBV) disrupts the interaction with cyclin B1, but not with other cyclin types; (iii) cyclin H is identified as a new high-affinity interactor of pUL97 in HCMV-infected cells; (iv) even more viral phosphoproteins, including all known substrates of pUL97, are detectable in the cyclin-associated complexes; and (v) a first functional validation of pUL97-cyclin B1 interaction, analyzed by in vitro kinase assay, points to a cyclin-mediated modulation of pUL97 substrate preference. In addition, our bioinformatic analyses suggest individual, cyclin-specific binding interfaces for pUL97-cyclin interaction, which could explain the different strengths of interactions and the selective inhibitory effect of MBV on pUL97-cyclin B1 interaction. Combined, the detection of cyclin-associated proteins in HCMV-infected cells suggests a complex pattern of substrate phosphorylation and a role of cyclins in the fine-modulation of pUL97 activities. PMID:27548200

  9. Proteomic Interaction Patterns between Human Cyclins, the Cyclin-Dependent Kinase Ortholog pUL97 and Additional Cytomegalovirus Proteins.

    PubMed

    Steingruber, Mirjam; Kraut, Alexandra; Socher, Eileen; Sticht, Heinrich; Reichel, Anna; Stamminger, Thomas; Amin, Bushra; Couté, Yohann; Hutterer, Corina; Marschall, Manfred

    2016-01-01

    The human cytomegalovirus (HCMV)-encoded cyclin-dependent kinase (CDK) ortholog pUL97 associates with human cyclin B1 and other types of cyclins. Here, the question was addressed whether cyclin interaction of pUL97 and additional viral proteins is detectable by mass spectrometry-based approaches. Proteomic data were validated by coimmunoprecipitation (CoIP), Western blot, in vitro kinase and bioinformatic analyses. Our findings suggest that: (i) pUL97 shows differential affinities to human cyclins; (ii) pUL97 inhibitor maribavir (MBV) disrupts the interaction with cyclin B1, but not with other cyclin types; (iii) cyclin H is identified as a new high-affinity interactor of pUL97 in HCMV-infected cells; (iv) even more viral phosphoproteins, including all known substrates of pUL97, are detectable in the cyclin-associated complexes; and (v) a first functional validation of pUL97-cyclin B1 interaction, analyzed by in vitro kinase assay, points to a cyclin-mediated modulation of pUL97 substrate preference. In addition, our bioinformatic analyses suggest individual, cyclin-specific binding interfaces for pUL97-cyclin interaction, which could explain the different strengths of interactions and the selective inhibitory effect of MBV on pUL97-cyclin B1 interaction. Combined, the detection of cyclin-associated proteins in HCMV-infected cells suggests a complex pattern of substrate phosphorylation and a role of cyclins in the fine-modulation of pUL97 activities. PMID:27548200

  10. Plant-to-Plant Variability in Root Metabolite Profiles of 19 Arabidopsis thaliana Accessions Is Substance-Class-Dependent.

    PubMed

    Mönchgesang, Susann; Strehmel, Nadine; Trutschel, Diana; Westphal, Lore; Neumann, Steffen; Scheel, Dierk

    2016-01-01

    Natural variation of secondary metabolism between different accessions of Arabidopsis thaliana (A. thaliana) has been studied extensively. In this study, we extended the natural variation approach by including biological variability (plant-to-plant variability) and analysed root metabolic patterns as well as their variability between plants and naturally occurring accessions. To screen 19 accessions of A. thaliana, comprehensive non-targeted metabolite profiling of single plant root extracts was performed using ultra performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS) and gas chromatography/electron ionization quadrupole mass spectrometry (GC/EI-QMS). Linear mixed models were applied to dissect the total observed variance. All metabolic profiles pointed towards a larger plant-to-plant variability than natural variation between accessions and variance of experimental batches. Ratios of plant-to-plant to total variability were high and distinct for certain secondary metabolites. None of the investigated accessions displayed a specifically high or low biological variability for these substance classes. This study provides recommendations for future natural variation analyses of glucosinolates, flavonoids, and phenylpropanoids and also reference data for additional substance classes. PMID:27649165

  11. Plant-to-Plant Variability in Root Metabolite Profiles of 19 Arabidopsis thaliana Accessions Is Substance-Class-Dependent

    PubMed Central

    Mönchgesang, Susann; Strehmel, Nadine; Trutschel, Diana; Westphal, Lore; Neumann, Steffen; Scheel, Dierk

    2016-01-01

    Natural variation of secondary metabolism between different accessions of Arabidopsis thaliana (A. thaliana) has been studied extensively. In this study, we extended the natural variation approach by including biological variability (plant-to-plant variability) and analysed root metabolic patterns as well as their variability between plants and naturally occurring accessions. To screen 19 accessions of A. thaliana, comprehensive non-targeted metabolite profiling of single plant root extracts was performed using ultra performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS) and gas chromatography/electron ionization quadrupole mass spectrometry (GC/EI-QMS). Linear mixed models were applied to dissect the total observed variance. All metabolic profiles pointed towards a larger plant-to-plant variability than natural variation between accessions and variance of experimental batches. Ratios of plant-to-plant to total variability were high and distinct for certain secondary metabolites. None of the investigated accessions displayed a specifically high or low biological variability for these substance classes. This study provides recommendations for future natural variation analyses of glucosinolates, flavonoids, and phenylpropanoids and also reference data for additional substance classes. PMID:27649165

  12. Intraspecies Variability Affects Heterotypic Biofilms of Porphyromonas gingivalis and Prevotella intermedia: Evidences of Strain-Dependence Biofilm Modulation by Physical Contact and by Released Soluble Factors.

    PubMed

    Barbosa, Graziela Murta; Colombo, Andrea Vieira; Rodrigues, Paulo Henrique; Simionato, Maria Regina Lorenzetti

    2015-01-01

    It is well known that strain and virulence diversity exist within the population structure of Porphyromonas gingivalis. In the present study we investigate intra- and inter-species variability in biofilm formation of Porphyromonas gingivalis and partners Prevotella intermedia and Prevotella nigrescens. All strains tested showed similar hydrophobicity, except for P. gingivalis W83 which has roughly half of the hydrophobicity of P. gingivalis ATCC33277. An intraspecies variability in coaggregation of P. gingivalis with P. intermedia was also found. The association P. gingivalis W83/P. intermedia 17 produced the thickest biofilm and strain 17 was prevalent. In a two-compartment system P. gingivalis W83 stimulates an increase in biomass of strain 17 and the latter did not stimulate the growth of P. gingivalis W83. In addition, P. gingivalis W83 also stimulates the growth of P. intermedia ATCC25611 although strain W83 was prevalent in the association with P. intermedia ATCC25611. P. gingivalis ATCC33277 was prevalent in both associations with P. intermedia and both strains of P. intermedia stimulate the growth of P. gingivalis ATCC33277. FISH images also showed variability in biofilm structure. Thus, the outcome of the association P. gingivalis/P. intermedia seems to be strain-dependent, and both soluble factors and physical contact are relevant. The association P. gingivalis-P. nigrescens ATCC33563 produced larger biomass than each monotypic biofilm, and P. gingivalis was favored in consortia, while no differences were found in the two-compartment system. Therefore, in consortia P. gingivalis-P. nigrescens physical contact seems to favor P. gingivalis growth. The intraspecies variability found in our study suggests strain-dependence in ability of microorganisms to recognize molecules in other bacteria which may further elucidate the dysbiosis event during periodontitis development giving additional explanation for periodontal bacteria, such as P. gingivalis and P

  13. Contact-dependent performance variability of monolayer MoS{sub 2} field-effect transistors

    SciTech Connect

    Han, Gyuchull; Yoon, Youngki

    2014-11-24

    Using self-consistent quantum transport simulations, we investigate the performance variability of monolayer molybdenum disulfide (MoS{sub 2}) field-effect transistors (FETs) with various contact properties. Varying the Schottky barrier in MoS{sub 2} FETs affects the output characteristics more significantly than the transfer characteristics. If doped contacts are realized, the performance variation due to non-ideal contacts becomes negligible; otherwise, channel doping can effectively suppress the performance variability in metal-contact devices. Our scaling study also reveals that for sub-10-nm channels, doped-contact devices can be more robust in terms of switching, while metal-contact MoS{sub 2} FETs can undergo the smaller penalty in output conductance.

  14. Striatal dopamine modulates basal ganglia output and regulates social context-dependent behavioral variability through D1 receptors

    PubMed Central

    Leblois, Arthur; Wendel, Benjamin J.; Perkel, David J

    2010-01-01

    Cortico–basal ganglia (BG) circuits are thought to promote the acquisition of motor skills through reinforcement learning. In songbirds, a specialized portion of the BG is responsible for song learning and plasticity. This circuit generates song variability that underlies vocal experimentation in young birds and modulates song variability depending on the social context in adult birds. When male birds sing in the presence of a female, a social context associated with decreased BG-induced song variability, the extracellular dopamine (DA) level is increased in the avian BG nucleus Area X. These results suggest that DA could trigger song variability changes through its action in Area X. Consistent with this hypothesis, we report that DA delivered to Area X weakens the output signal of the avian cortico-BG circuit. Acting through D1 receptors, DA reduced responses in Area X to song playback and to electrical stimulation of its afferent cortical nucleus HVC. Specifically, DA reduced the response to direct excitatory input and decreased firing variability in Area X pallidal neurons, which provide the output to the thalamus. As a consequence, DA delivery in Area X also decreased responses to song playback in the cortical output nucleus of the BG loop, the lateral magnocellular nucleus of the anterior nidopallium (LMAN). Further, interfering with D1 receptor transmission in Area X abolished social context-related changes in song variability. In conclusion, we propose that DA acts on D1 receptors in Area X to modulate the BG output signal and trigger changes in song variability. PMID:20410125

  15. Gains from modelling dependence of rainfall variables into a stochastic model: application of the copula approach at several sites

    NASA Astrophysics Data System (ADS)

    Cantet, P.; Arnaud, P.

    2012-10-01

    Since the last decade, copulas have become more and more widespread in the construction of hydrological models. Unlike the multivariate statistics which are traditionally used, this tool enables scientists to model different dependence structures without drawbacks. The authors propose to apply copulas to improve the performance of an existing model. The hourly rainfall stochastic model SHYPRE is based on the simulation of descriptive variables. It generates long series of hourly rainfall and enables the estimation of distribution quantiles for different climates. The paper focuses on the relationship between two variables describing the rainfall signal. First, Kendall's tau is estimated on each of the 217 rain gauge stations in France, then the False Discovery Rate procedure is used to define stations for which the dependence is significant. Among three usual archimedean copulas, a unique 2-copula is chosen to model this dependence for any station. Modelling dependence leads to an obvious improvement in the reproduction of the standard and extreme statistics of maximum rainfall, especially for the sub-daily rainfall. An accuracy test for the extreme values shows the good asymptotic behaviour of the new rainfall generator version and the impacts of the copula choice on extreme quantile estimation.

  16. The Relationships between Cognitive Style of Field Dependence and Learner Variables in E-Learning Instruction

    ERIC Educational Resources Information Center

    Sozcu, Omer Faruk

    2014-01-01

    This study examines the relationships between cognitive styles of field dependent learners with their attitudes towards e-learning (distance education) and instructional behavior in e-learning instruction. The Group Embedded Figures Test (GEFT) and the attitude survey (for students' preferences) towards e-learning instruction as distance…

  17. Spatial and temporal variability modify density dependence in populations of large herbivores.

    PubMed

    Wang, Guiming; Hobbs, N Thompson; Boone, Randall B; Illius, Andrew W; Gordon, Iain J; Gross, John E; Hamlin, Kenneth L

    2006-01-01

    A central challenge in ecology is to understand the interplay of internal and external controls on the growth of populations. We examined the effects of temporal variation in weather and spatial variation in vegetation on the strength of density dependence in populations of large herbivores. We fit three subsets of the model ln(Nt) = a + (1 + b) x ln(N(t-1)) + c x ln(N(t-2)) to five time series of estimates (Nt) of abundance of ungulates in the Rocky Mountains, USA. The strength of density dependence was estimated by the magnitude of the coefficient b. We regressed the estimates of b on indices of temporal heterogeneity in weather and spatial heterogeneity in resources. The 95% posterior intervals of the slopes of these regressions showed that temporal heterogeneity strengthened density-dependent feedbacks to population growth, whereas spatial heterogeneity weakened them. This finding offers the first empirical evidence that density dependence responds in different ways to spatial heterogeneity and temporal heterogeneity. PMID:16634300

  18. Field Dependence-Independence as a Variable in Second Language Cloze Test Performance.

    ERIC Educational Resources Information Center

    Stansfield, Charles; Hansen, Jacqueline

    1983-01-01

    A study of test performance and field dependent-independent (FD/I) cognitive style in 250 college students showed consistently positive correlation between FI and cloze test scores, and other measures such as final grade. It is suggested cloze tests may call forth cognitive restructuring capabilities more easily for more field independent…

  19. Management-dependent soil property variability of Southeastern U.S. Coastal Plain plinthic kandiudults

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The National Cooperative Soil Survey (NCSS) defines a management or use-dependent property as a type of dynamic soil property which changes on a human time-scale due to anthropogenic disturbances (indicative of soil change). Interest in soil change and C sequestration has led to increased emphasis ...

  20. Time dependent analysis of assay comparability: a novel approach to understand intra- and inter-site variability over time.

    PubMed

    Winiwarter, Susanne; Middleton, Brian; Jones, Barry; Courtney, Paul; Lindmark, Bo; Page, Ken M; Clark, Alan; Landqvist, Claire

    2015-09-01

    We demonstrate here a novel use of statistical tools to study intra- and inter-site assay variability of five early drug metabolism and pharmacokinetics in vitro assays over time. Firstly, a tool for process control is presented. It shows the overall assay variability but allows also the following of changes due to assay adjustments and can additionally highlight other, potentially unexpected variations. Secondly, we define the minimum discriminatory difference/ratio to support projects to understand how experimental values measured at different sites at a given time can be compared. Such discriminatory values are calculated for 3 month periods and followed over time for each assay. Again assay modifications, especially assay harmonization efforts, can be noted. Both the process control tool and the variability estimates are based on the results of control compounds tested every time an assay is run. Variability estimates for a limited set of project compounds were computed as well and found to be comparable. This analysis reinforces the need to consider assay variability in decision making, compound ranking and in silico modeling.

  1. Time dependent analysis of assay comparability: a novel approach to understand intra- and inter-site variability over time.

    PubMed

    Winiwarter, Susanne; Middleton, Brian; Jones, Barry; Courtney, Paul; Lindmark, Bo; Page, Ken M; Clark, Alan; Landqvist, Claire

    2015-09-01

    We demonstrate here a novel use of statistical tools to study intra- and inter-site assay variability of five early drug metabolism and pharmacokinetics in vitro assays over time. Firstly, a tool for process control is presented. It shows the overall assay variability but allows also the following of changes due to assay adjustments and can additionally highlight other, potentially unexpected variations. Secondly, we define the minimum discriminatory difference/ratio to support projects to understand how experimental values measured at different sites at a given time can be compared. Such discriminatory values are calculated for 3 month periods and followed over time for each assay. Again assay modifications, especially assay harmonization efforts, can be noted. Both the process control tool and the variability estimates are based on the results of control compounds tested every time an assay is run. Variability estimates for a limited set of project compounds were computed as well and found to be comparable. This analysis reinforces the need to consider assay variability in decision making, compound ranking and in silico modeling. PMID:25697964

  2. Studying the time scale dependence of environmental variables predictability using fractal analysis.

    PubMed

    Yuval; Broday, David M

    2010-06-15

    Prediction of meteorological and air quality variables motivates a lot of research in the atmospheric sciences and exposure assessment communities. An interesting related issue regards the relative predictive power that can be expected at different time scales, and whether it vanishes altogether at certain ranges. An improved understanding of our predictive powers enables better environmental management and more efficient decision making processes. Fractal analysis is commonly used to characterize the self-affinity of time series. This work introduces the Continuous Wavelet Transform (CWT) fractal analysis method as a tool for assessing environmental time series predictability. The high temporal scale resolution of the CWT enables detailed information about the Hurst parameter, a common temporal fractality measure, and thus about time scale variations in predictability. We analyzed a few years records of half-hourly air pollution and meteorological time series from which the trivial seasonal and daily cycles were removed. We encountered a general trend of decreasing Hurst values from about 1.4 (good autocorrelation and predictability), in the sub-daily time scale to 0.5 (which implies complete randomness) in the monthly to seasonal scales. The air pollutants predictability follows that of the meteorological variables in the short time scales but is better at longer scales.

  3. The temperature size rule in arthropods: independent of macro-environmental variables but size dependent.

    PubMed

    Klok, C Jaco; Harrison, Jon F

    2013-10-01

    Temperature is a key factor that affects the rates of growth and development in animals, which ultimately determine body size. Although not universal, a widely documented and poorly understood pattern is the inverse relationship between the temperature at which an ectothermic animal is reared and its body size (temperature size rule [TSR]). The proximate and ultimate mechanisms for the TSR remain unclear. To explore possible explanations for the TSR, we tested for correlations between the magnitude/direction of the TSR and latitude, temperature, elevation, habitat, availability of oxygen, capacity for flight, and taxonomic grouping in 98 species/populations of arthropods. The magnitude and direction of the TSR was not correlated with any of the macro-environmental variables we examined, supporting the generality of the TSR. However, body size affected the magnitude and direction of the TSR, with smaller arthropods more likely to demonstrate a classic TSR. Considerable variation among species exists in the TSR, suggesting either strong interactions with nutrition, or selection based on microclimatic or seasonal variation not captured in classic macro-environmental variables.

  4. Evaluation of sampling techniques to characterize topographically-dependent variability for soil moisture downscaling

    NASA Astrophysics Data System (ADS)

    Werbylo, Kevin L.; Niemann, Jeffrey D.

    2014-08-01

    Downscaling methods have been proposed to estimate catchment-scale soil moisture patterns from coarser resolution patterns. These methods usually infer the fine-scale variability in soil moisture using variations in ancillary variables like topographic attributes that have relationships to soil moisture. Previously, such relationships have been observed in catchments using soil moisture observations taken on uniform grids at hundreds of locations on multiple dates, but collecting data in this manner limits the applicability of this approach. The objective of this paper is to evaluate the effectiveness of two strategic sampling techniques for characterizing the relationships between topographic attributes and soil moisture for the purpose of constraining downscaling methods. The strategic sampling methods are conditioned Latin hypercube sampling (cLHS) and stratified random sampling (SRS). Each sampling method is used to select a limited number of locations or dates for soil moisture monitoring at three catchments with detailed soil moisture datasets. These samples are then used to calibrate two available downscaling methods, and the effectiveness of the sampling methods is evaluated by the ability of the downscaling methods to reproduce the known soil moisture patterns. cLHS outperforms random sampling in almost every case considered. SRS usually performs better than cLHS when very few locations are sampled, but it can perform worse than random sampling for intermediate and large numbers of locations.

  5. Including long-range dependence in integrate-and-fire models of the high interspike-interval variability of cortical neurons.

    PubMed

    Jackson, B Scott

    2004-10-01

    spike trains with interspike-interval variability and long-range dependence that match empirical data from cortical spike trains. This model is similar to the other models in this study, except that its inputs are fractional-gaussian-noise-driven Poisson processes rather than renewal point processes. In addition to this model's success in producing realistic output spike trains, its inputs have long-range dependence similar to that found in most subcortical neurons in sensory pathways, including the inputs to cortex. Analysis of output spike trains from simulations of this model also shows that a tight balance between the amounts of excitation and inhibition at the inputs to cortical neurons is not necessary for high interspike-interval variability at their outputs. Furthermore, in our analysis of this model, we show that the superposition of many fractional-gaussian-noise-driven Poisson processes does not approximate a Poisson process, which challenges the common assumption that the total effect of a large number of inputs on a neuron is well represented by a Poisson process.

  6. Variability in projected elevation dependent warming in boreal midlatitude winter in CMIP5 climate models and its potential drivers

    NASA Astrophysics Data System (ADS)

    Rangwala, Imtiaz; Sinsky, Eric; Miller, James R.

    2016-04-01

    The future rate of climate change in mountains has many potential human impacts, including those related to water resources, ecosystem services, and recreation. Analysis of the ensemble mean response of CMIP5 global climate models (GCMs) shows amplified warming in high elevation regions during the cold season in boreal midlatitudes. We examine how the twenty-first century elevation-dependent response in the daily minimum surface air temperature [d(ΔTmin)/dz] varies among 27 different GCMs during winter for the RCP 8.5 emissions scenario. The focus is on regions within the northern hemisphere mid-latitude band between 27.5°N and 40°N, which includes both the Rocky Mountains and the Tibetan Plateau/Himalayas. We find significant variability in d(ΔTmin)/dz among the individual models ranging from 0.16 °C/km (10th percentile) to 0.97 °C/km (90th percentile), although nearly all of the GCMs (24 out of 27) show a significant positive value for d(ΔTmin)/dz. To identify some of the important drivers associated with the variability in d(ΔTmin)/dz during winter, we evaluate the co-variance between d(ΔTmin)/dz and the differential response of elevation-based anomalies in different climate variables as well as the GCMs' spatial resolution, their global climate sensitivity, and their elevation-dependent free air temperature response. We find that d(ΔTmin)/dz has the strongest correlation with elevation-dependent increases in surface water vapor, followed by elevation-dependent decreases in surface albedo, and a weak positive correlation with the GCMs' free air temperature response.

  7. Determination of organic additives in mortars by near-IR spectroscopy. A novel approach to designing a sample set with high-variability components.

    PubMed

    Blanco, Marcelo; Peguero, Anna

    2007-02-01

    Industrial mortars consist primarily of a mixture of cement and an aggregate plus a small amount of additives that are used to modify specific properties. Using too high or too low additive rates usually results in the loss of desirable properties in the end product. This entails carefully controlling the amounts of additives added to mortar in order to ensure correct dosing and/or adequate homogeneity in the final mixture. Near-IR (NIR) spectroscopy has proved effective for this purpose as it requires no sample pretreatment and affords expeditious analyses. The purpose of this work was to determine two organic additives (viz. Ad1 and Ad2) in mortars by using partial least squares regression multivariate calibration models constructed from NIR spectroscopic data. The additives are used to expedite setting and increase cohesion between particles in the mortar. In order to ensure that the sample set contained natural variability in the samples, we used a methodology based on experimental design to construct a representative set of samples. This novel design is based on a hexagonal antiprism that encompasses the concentration ranges spanned by the analytes and the variability inherent in each additive. The D-optimality criterion was used to obtain various combinations between Ad1 and Ad2 additive classes. The partial least squares calibration models thus constructed for each additive provided accurate predictions: the intercept and the slope of the plots of predicted values versus reference values for each additive were close to 0 and 1, respectively, and their confidence ranges included the respective value. The ensuing analytical methods were validated by using an external sample set.

  8. Adaptive cancellation of variable feedback path for hearing aid using misalignment-dependent step size values.

    PubMed

    Khoubrouy, Soudeh A; Panahi, Issa M S

    2011-01-01

    Various methods have been proposed to overcome the problem of compensating the acoustic feedback path that negatively impacts the performance of hearing aid devices. However, in most of them feedback path model is assumed to be fixed which is not quite realistic. In this paper, we consider fixed and variable feedback paths and analyze for each case the performance of one of the robust Adaptive Feedback Cancellation (AFC) schemes, i.e. the Prediction Error Method AFC which uses Partitioned Block Frequency-Domain Normalized Least Mean Square (PBFD-NLMS) algorithm. Based on the analysis results we propose varying the step size values for the same adaptive algorithm on the fly by monitoring the misalignment criteria. The experimental results using the proposed method show improvement made on the system performance. PMID:22256175

  9. Dependence of three variables on the social vulnerability of 497 districts in Indonesia

    NASA Astrophysics Data System (ADS)

    Faiz, Muhammad Fadli; Sa'idah, NurFaizatus

    2015-12-01

    Here we present about social vulnerability in Indonesia. Our study is to analyze relationship between at least 3 characteristics which effecting social vulnerability using correlation analysis. Actually, ten variables which defined as social vulnerability, but we decided as 3 main characteristics; percentage of female population, rate of population increase, and percentage of poor population. The study shows that percentage of female population and rate of population increase has - 0,153 correlation. Other method, that is Principal Component Analysis (PCA) also applied. This analysis also give 3 main characteristics from 184 districts with female population ≥ 50% in Indonesia. We hope, this study can be one of reference in determining principle component that effecting social vulnerability for helping communities better prepare for any disaster.

  10. Dependence of P-wave dispersion on mean arterial pressure as an independent hemodynamic variable in school children

    PubMed Central

    González, Emilio F.; Llanes, María del Carmen; Llanes, Merlin Garí; García, Yosvany

    2013-01-01

    Introduction: The relationship between diastolic dysfunction and P-wave dispersion (PWD) in the electrocardiogram has been studied for some time. In this regard, echocardiography is emerging as a diagnostic tool to improve risk stratification for mild hypertension. Objective: To determine the dependence of PWD on the electrocardiogram and on echocardiographic variables in a pediatric population. Methods: 515 children from three elementary schools were studied from a total of 565 children. Those whose parents did not want them to take part in the study, as well as those with known congenital diseases, were excluded. Tests including 12-lead surface ECGs and 4 blood pressure (BP) measurements were performed. Maximum and minimum P-values were measured, and the PWD on the electrocardiogram was calculated. Echocardiography for structural measurements and the pulsed Doppler of mitral flow were also performed. Results: A significant correlation in statistical variables was found between PWD and mean BP for pre-hypertensive and hypertensive children, i.e., r = 0.32, p <0.01 and r = 0.33, p <0.01, respectively. There was a significant correlation found between PWD and the left atrial area (r = 0.45 and p <0.01). Conclusions: We highlight the dependency between PWD, the electrocardiogram and mean blood pressure. We also draw attention to the dependence of PWD on the duration of the mitral inflow A-wave. This result provides an explanation for earlier changes in atrial electrophysiological and hemodynamic characteristics in pediatric patients. PMID:24892616

  11. Fast-axis orientation dependence on driving voltage for a Stokes polarimeter based on concrete liquid-crystal variable retarders.

    PubMed

    Terrier, P; Charbois, J M; Devlaminck, V

    2010-08-01

    Nowadays liquid-crystal variable retarders (LCVRs) are widely used in optical systems because of their capacity to provide a controlled variable optical retardance by means of an applied voltage, without the need of any moving mechanical part. Nevertheless, the main disadvantages of these components, reported by users in several papers, are the necessity of using a temperature control system for precise measurements, the degradation under UV irradiation, and the lack of spatial retardance homogeneity. In this paper, we report that the orientation of the LCVR fast axis may also be dependent on applied voltage. The consideration of this phenomenon improves the performances of an imaging polarimeter. In this work, we present the problem, introduce the method of calibration that was used for the experiment, and discuss the results. PMID:20676183

  12. Basal variability in CREB phosphorylation predicts trait-like differences in amygdala-dependent memory.

    PubMed

    Cowansage, Kiriana K; Bush, David E A; Josselyn, Sheena A; Klann, Eric; Ledoux, Joseph E

    2013-10-01

    Much of what is known about the neurobiology of learning and memory comes from studies of the average behavior. In contrast, intersubject differences that emerge within groups are difficult to study systematically and are often excluded from scientific discussion. Nevertheless, population-wide variability is a virtually universal feature of both complex traits, such as intelligence, and hardwired responses, such as defensive behaviors. Here, we use outbred rats to investigate if cAMP response element-binding protein (CREB), a transcription factor that has long been known in experimental settings to be crucial for associative plasticity, participates in natural memory phenotypes. Using a combination of behavioral, biochemical, and viral techniques, we show that a subset of rats with trait-like deficits in aversive memory have basally reduced CREB activity in the lateral amygdala but can be induced to perform at average levels by directly or indirectly enhancing pretraining CREB phosphorylation. These data suggest that endogenous CREB activity in the amygdala may set a critical threshold for plasticity during memory formation. PMID:24062441

  13. Scale-dependency of the hydraulic properties of a variably saturated heterogeneous sandy subsoil

    NASA Astrophysics Data System (ADS)

    Javaux, M.; Vanclooster, M.

    2006-08-01

    SummaryThe effective hydraulic behaviour of heterogeneous sand was experimentally investigated at two scales under transient flow upper boundary conditions. At the monoliths-scale, one-dimensional inverse modelling was performed from a transient infiltration experiment by implementing in the objective function the outflow and pressure head time series at four depths. Notwithstanding the important heterogeneity of the subsoil, principally due to the presence of discontinuous clay and a stone layer, we observed that the effective behaviour was surprisingly well reproduced. It was also observed that the structural features mainly induced a kind of hysteresis between the saturation and drainage cycles of the outflow time series. Subsequently, 104 Kopecky cores (100 cm 3) were sub-sampled throughout the monolith, mainly in the sandy matrix. The variability of local hydraulic parameters was investigated by optimising the local hydraulic parameters from multi-step outflow experiments and measured retention points. The comparison between 1-D optimised, measured and Kopecky-averaged retention curves showed relatively similar shape near saturation. In contrast to this, important discrepancies existed between averaged local scale hydraulic conductivity and effective hydraulic conductivity close to saturation. Different experimental designs at different scales may explain the observed discrepancies. It is further suggested that the monolith-scale effective hydraulic functions are more representative for wet soil conditions. This case study illustrates the complexity of finding validated scaling relationships for the hydraulic properties of heterogeneous soils at scales larger than the usual small column scale.

  14. Spatio-temporal dependencies between hospital beds, physicians and health expenditure using visual variables and data classification in statistical table

    NASA Astrophysics Data System (ADS)

    Medyńska-Gulij, Beata; Cybulski, Paweł

    2016-06-01

    This paper analyses the use of table visual variables of statistical data of hospital beds as an important tool for revealing spatio-temporal dependencies. It is argued that some of conclusions from the data about public health and public expenditure on health have a spatio-temporal reference. Different from previous studies, this article adopts combination of cartographic pragmatics and spatial visualization with previous conclusions made in public health literature. While the significant conclusions about health care and economic factors has been highlighted in research papers, this article is the first to apply visual analysis to statistical table together with maps which is called previsualisation.

  15. Timing variability analysis for layout-dependent-effects in 28nm custom and standard cell-based designs

    NASA Astrophysics Data System (ADS)

    Hurat, Philippe; Topaloglu, Rasit O.; Nachman, Ramez; Pathak, Piyush; Condella, Jac; Madhavan, Sriram; Capodieci, Luigi

    2011-04-01

    We identify most recent sources of transistor layout dependent effects (LDE) such as stress, lithography, and well proximity effects (WPE), and outline modeling and analysis methods for 28 nm. These methods apply to custom layout, standard cell designs, and context-aware post-route analysis. We show how IC design teams can use a model-based approach to quantify and analyze variability induced by LDE. We reduce the need for guard-bands that negate the performance advantages that stress brings to advanced process technologies.

  16. ENERGY-DEPENDENT POWER SPECTRAL STATES AND ORIGIN OF APERIODIC VARIABILITY IN BLACK HOLE BINARIES

    SciTech Connect

    Yu Wenfei; Zhang Wenda

    2013-06-20

    We found that the black hole candidate MAXI J1659-152 showed distinct power spectra, i.e., power-law noise (PLN) versus band-limited noise (BLN) plus quasi-periodic oscillations (QPOs) below and above about 2 keV, respectively, in observations with Swift and the Rossi X-ray Timing Explorer during the 2010 outburst, indicating a high energy cutoff of the PLN and a low energy cutoff of the BLN and QPOs around 2 keV. The emergence of the PLN and the fading of the BLN and QPOs initially took place below 2 keV when the source entered the hard intermediate state and settled in the soft state three weeks later. The evolution was accompanied by the emergence of the disk spectral component and decreases in the amplitudes of variability in the soft and hard X-ray bands. Our results indicate that the PLN is associated with an optically thick disk in both hard and intermediate states, and the power spectral state is independent of the X-ray energy spectral state in a broadband view. We suggest that in the hard or intermediate state, the BLN and QPOs emerge from the innermost hot flow subjected to Comptonization, while the PLN originates from the optically thick disk farther out. The energy cutoffs of the PLN and the BLN or QPOs then follow the temperature of the seed photons from the inner edge of the optically thick disk, while the high frequency cutoff of the PLN follows the orbital frequency of the inner edge of the optically thick disk as well.

  17. Energy-dependent Power Spectral States and Origin of Aperiodic Variability in Black Hole Binaries

    NASA Astrophysics Data System (ADS)

    Yu, Wenfei; Zhang, Wenda

    2013-06-01

    We found that the black hole candidate MAXI J1659-152 showed distinct power spectra, i.e., power-law noise (PLN) versus band-limited noise (BLN) plus quasi-periodic oscillations (QPOs) below and above about 2 keV, respectively, in observations with Swift and the Rossi X-ray Timing Explorer during the 2010 outburst, indicating a high energy cutoff of the PLN and a low energy cutoff of the BLN and QPOs around 2 keV. The emergence of the PLN and the fading of the BLN and QPOs initially took place below 2 keV when the source entered the hard intermediate state and settled in the soft state three weeks later. The evolution was accompanied by the emergence of the disk spectral component and decreases in the amplitudes of variability in the soft and hard X-ray bands. Our results indicate that the PLN is associated with an optically thick disk in both hard and intermediate states, and the power spectral state is independent of the X-ray energy spectral state in a broadband view. We suggest that in the hard or intermediate state, the BLN and QPOs emerge from the innermost hot flow subjected to Comptonization, while the PLN originates from the optically thick disk farther out. The energy cutoffs of the PLN and the BLN or QPOs then follow the temperature of the seed photons from the inner edge of the optically thick disk, while the high frequency cutoff of the PLN follows the orbital frequency of the inner edge of the optically thick disk as well.

  18. Advanced alpha spectrum analysis based on the fitting and covariance analysis of dependent variables

    NASA Astrophysics Data System (ADS)

    Ihantola, S.; Pelikan, A.; Pöllänen, R.; Toivonen, H.

    2011-11-01

    The correct handling of statistical uncertainties is crucial especially when unfolding alpha spectra that contain a low number of counts or overlapping peaks from different nuclides. For this purpose, we have developed a new spectrum analysis software package called ADAM, which performs a full covariance calculus for alpha-particle emitting radionuclides. By analyzing a large number of simulated and measured spectra, the program was proved to give unbiased peak areas and statistically correct uncertainty limits. This applies regardless of the peak areas and the number of unknown parameters during the fitting. In addition, ADAM performs reliable deconvolution for multiplets, which opens the way for the determination of isotope ratios, such as 239Pu/240Pu.

  19. Impacts of nitrogen addition on plant biodiversity in mountain grasslands depend on dose, application duration and climate: a systematic review.

    PubMed

    Humbert, Jean-Yves; Dwyer, John M; Andrey, Aline; Arlettaz, Raphaël

    2016-01-01

    Although the influence of nitrogen (N) addition on grassland plant communities has been widely studied, it is still unclear whether observed patterns and underlying mechanisms are constant across biomes. In this systematic review, we use meta-analysis and metaregression to investigate the influence of N addition (here referring mostly to fertilization) upon the biodiversity of temperate mountain grasslands (including montane, subalpine and alpine zones). Forty-two studies met our criteria of inclusion, resulting in 134 measures of effect size. The main general responses of mountain grasslands to N addition were increases in phytomass and reductions in plant species richness, as observed in lowland grasslands. More specifically, the analysis reveals that negative effects on species richness were exacerbated by dose (ha(-1) year(-1) ) and duration of N application (years) in an additive manner. Thus, sustained application of low to moderate levels of N over time had effects similar to short-term application of high N doses. The climatic context also played an important role: the overall effects of N addition on plant species richness and diversity (Shannon index) were less pronounced in mountain grasslands experiencing cool rather than warm summers. Furthermore, the relative negative effect of N addition on species richness was more pronounced in managed communities and was strongly negatively related to N-induced increases in phytomass, that is the greater the phytomass response to N addition, the greater the decline in richness. Altogether, this review not only establishes that plant biodiversity of mountain grasslands is negatively affected by N addition, but also demonstrates that several local management and abiotic factors interact with N addition to drive plant community changes. This synthesis yields essential information for a more sustainable management of mountain grasslands, emphasizing the importance of preserving and restoring grasslands with both low

  20. Impacts of nitrogen addition on plant biodiversity in mountain grasslands depend on dose, application duration and climate: a systematic review.

    PubMed

    Humbert, Jean-Yves; Dwyer, John M; Andrey, Aline; Arlettaz, Raphaël

    2016-01-01

    Although the influence of nitrogen (N) addition on grassland plant communities has been widely studied, it is still unclear whether observed patterns and underlying mechanisms are constant across biomes. In this systematic review, we use meta-analysis and metaregression to investigate the influence of N addition (here referring mostly to fertilization) upon the biodiversity of temperate mountain grasslands (including montane, subalpine and alpine zones). Forty-two studies met our criteria of inclusion, resulting in 134 measures of effect size. The main general responses of mountain grasslands to N addition were increases in phytomass and reductions in plant species richness, as observed in lowland grasslands. More specifically, the analysis reveals that negative effects on species richness were exacerbated by dose (ha(-1) year(-1) ) and duration of N application (years) in an additive manner. Thus, sustained application of low to moderate levels of N over time had effects similar to short-term application of high N doses. The climatic context also played an important role: the overall effects of N addition on plant species richness and diversity (Shannon index) were less pronounced in mountain grasslands experiencing cool rather than warm summers. Furthermore, the relative negative effect of N addition on species richness was more pronounced in managed communities and was strongly negatively related to N-induced increases in phytomass, that is the greater the phytomass response to N addition, the greater the decline in richness. Altogether, this review not only establishes that plant biodiversity of mountain grasslands is negatively affected by N addition, but also demonstrates that several local management and abiotic factors interact with N addition to drive plant community changes. This synthesis yields essential information for a more sustainable management of mountain grasslands, emphasizing the importance of preserving and restoring grasslands with both low

  1. Variable Antibody-dependent Activation of Complement by Functionalized Phospholipid Nanoparticle Surfaces*

    PubMed Central

    Pham, Christine T. N.; Mitchell, Lynne M.; Huang, Jennifer L.; Lubniewski, Christopher M.; Schall, Otto F.; Killgore, J. Kendall; Pan, Dipanjan; Wickline, Samuel A.; Lanza, Gregory M.; Hourcade, Dennis E.

    2011-01-01

    A wide variety of nanomaterials are currently being developed for use in the detection and treatment of human diseases. However, there is no systematic way to measure and predict the action of such materials in biological contexts. Lipid-encapsulated nanoparticles (NPs) are a class of nanomaterials that includes the liposomes, the most widely used and clinically proven type of NPs. Liposomes can, however, activate the complement system, an important branch of innate immunity, resulting in undesirable consequences. Here, we describe the complement response to lipid-encapsulated NPs that are functionalized on the surface with various lipid-anchored gadolinium chelates. We developed a quantitative approach to examine the interaction of NPs with the complement system using in vitro assays and correlating these results with those obtained in an in vivo mouse model. Our results indicate that surface functionalization of NPs with certain chemical structures elicits swift complement activation that is initiated by a natural IgM antibody and propagated via the classical pathway. The intensity of the response is dependent on the chemical structures of the lipid-anchored chelates and not zeta potential effects alone. Moreover, the extent of complement activation may be tempered by complement inhibiting regulatory proteins that bind to the surface of NPs. These findings represent a step forward in the understanding of the interactions between nanomaterials and the host innate immune response and provide the basis for a systematic structure-activity relationship study to establish guidelines that are critical to the future development of biocompatible nanotherapeutics. PMID:21047788

  2. X-ray Variability Characteristics of the Narrow line SEYFERT 1 MKN 766 I: Energy Dependent Timing Properties

    NASA Technical Reports Server (NTRS)

    Markowitz, A.; Turner, T. J.; Papadakis, I.; Arevalo, P.; Reeves, J. N.; Miller, L.

    2007-01-01

    We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766 obtained from a six-revolution XMM-Newton observation in 2005. The resulting PSDs, which have highest temporal frequency resolution for an AGN PSD to date, show breaks which increase in temporal frequency as photon energy increases; break frequencies differ by an average of approx.0.4 in the log between the softest and hardest bands. The consistency of the 2001 and 2005 observations variability properties, namely PSD shapes and the linear rms-flux relation, suggests the 2005 observation is simply a low-flux extension of the 2001 observation. The coherence function is measured to be approx.0.6-0.9 at temporal frequencies below the PSD break, and is lower for relatively larger energy band separation; coherence also drops significantly towards zero above the PSD break frequency. Temporal frequency-dependent soft-to-hard time lags are detected in this object for the first time: lags increase towards longer time scales and as energy separation increases. Cross-spectral properties are the thus consistent with previous measurements for Mkn 766 (Vaughan & Fabian 2003) and other accreting black hole systems. The results are discussed in the context of several variability models, including those based on inwardly-propagating viscosity variations in the accretion disk.

  3. An Efficient Sampling Technique for Observing Topographically-Dependent Spatial Variability in Catchment-Scale Soil Moisture Patterns

    NASA Astrophysics Data System (ADS)

    Werbylo, K. L.; Niemann, J. D.

    2012-12-01

    stratifications for each variable or the number of locations sampled in each joint stratification. The locations selected from the stratified sampling method can also be supplemented with random locations. The method is applied to three different catchments: Tarrawarra, Satellite Station, and Cache la Poudre. The observations are used to calibrate a conceptual model known as the Equilibrium Moisture from Topography (EMT) model and an empirical model based on empirical orthogonal function (EOF) analysis. The efficiency of the sampling method is evaluated by the models' ability to reproduce the soil moisture values at unobserved locations. The stratified method is also compared to a random sampling method. The results show that both the random and stratified sampling methods can characterize the soil moisture variation with many fewer locations than have been collected previously. In addition, the stratified sampling method exhibits much better performance than random sampling when relatively few observations are collected.

  4. Insulin-dependent glucose metabolism in dairy cows with variable fat mobilization around calving.

    PubMed

    Weber, C; Schäff, C T; Kautzsch, U; Börner, S; Erdmann, S; Görs, S; Röntgen, M; Sauerwein, H; Bruckmaier, R M; Metges, C C; Kuhla, B; Hammon, H M

    2016-08-01

    fatty acids decreased during HGC and EGHIC, but in both clamps, pp nonesterified fatty acid concentrations did not reach the ap levels. The study demonstrated a minor influence of different degrees of body fat mobilization on insulin metabolism in cows during the transition period. The distinct decrease in the glucose-dependent release of insulin pp is the most striking finding that explains the impaired insulin action after calving, but does not explain differences in body fat mobilization between HLFC and LLFC cows. PMID:27179866

  5. Nitrogen-Dependent Regulation of De Novo Cytokinin Biosynthesis in Rice: The Role of Glutamine Metabolism as an Additional Signal

    PubMed Central

    Kamada-Nobusada, Tomoe; Makita, Nobue; Kojima, Mikiko; Sakakibara, Hitoshi

    2013-01-01

    Cytokinin activity in plants is closely related to nitrogen availability, and an Arabidopsis gene for adenosine phosphate-isopentenyltransferase (IPT), IPT3, is regulated by inorganic nitrogen sources in a nitrate-specific manner. In this study, we have identified another regulatory system of cytokinin de novo biosynthesis in response to nitrogen status. In rice, OsIPT4, OsIPT5, OsIPT7 and OsIPT8 were up-regulated in response to exogenously applied nitrate and ammonium, with accompanying accumulation of cytokinins. Pre-treatment of roots with l-methionine sulfoximine, a potent inhibitor of glutamine synthetase, abolished the nitrate- and ammonium-dependent induction of OsIPT4 and OsIPT5, while glutamine application induced their expression. Thus, neither nitrate nor ammonium, but glutamine or a related metabolite, is essential for the induction of these IPT genes in rice. On the other hand, glutamine-dependent induction of IPT3 occurs in Arabidopsis, at least to some extent. In transgenic lines repressing the expression of OsIPT4, which is the dominant IPT in rice roots, the nitrogen-dependent increase of cytokinin in the xylem sap was significantly reduced, and seedling shoot growth was retarded despite sufficient nitrogen. We conclude that plants possess multiple regulation systems for nitrogen-dependent cytokinin biosynthesis to modulate growth in response to nitrogen availability. PMID:24058148

  6. Outcome-dependent sampling for longitudinal binary response data based on a time-varying auxiliary variable.

    PubMed

    Schildcrout, Jonathan S; Mumford, Sunni L; Chen, Zhen; Heagerty, Patrick J; Rathouz, Paul J

    2012-09-28

    Outcome-dependent sampling (ODS) study designs are commonly implemented with rare diseases or when prospective studies are infeasible. In longitudinal data settings, when a repeatedly measured binary response is rare, an ODS design can be highly efficient for maximizing statistical information subject to resource limitations that prohibit covariate ascertainment of all observations. This manuscript details an ODS design where individual observations are sampled with probabilities determined by an inexpensive, time-varying auxiliary variable that is related but is not equal to the response. With the goal of validly estimating marginal model parameters based on the resulting biased sample, we propose a semi-parametric, sequential offsetted logistic regressions (SOLR) approach. The SOLR strategy first estimates the relationship between the auxiliary variable and the response and covariate data by using an offsetted logistic regression analysis where the offset is used to adjust for the biased design. Results from the auxiliary variable model are then combined with the known or estimated sampling probabilities to formulate a second offset that is used to correct for the biased design in the ultimate target model relating the longitudinal binary response to covariates. Because the target model offset is estimated with SOLR, we detail asymptotic standard error estimates that account for uncertainty associated with the auxiliary variable model. Motivated by an analysis of the BioCycle Study (Gaskins et al., Effect of daily fiber intake on reproductive function: the BioCycle Study. American Journal of Clinical Nutrition 2009; 90(4): 1061-1069) that aims to describe the relationship between reproductive health (determined by luteinizing hormone levels) and fiber consumption, we examine properties of SOLR estimators and compare them with other common approaches.

  7. Outcome-dependent sampling for longitudinal binary response data based on a time-varying auxiliary variable

    PubMed Central

    Schildcrout, Jonathan S.; Mumford, Sunni L.; Chen, Zhen; Heagerty, Patrick J.; Rathouz, Paul J.

    2012-01-01

    Outcome-dependent sampling (ODS) study designs are commonly implemented with rare diseases or when prospective studies are infeasible. In longitudinal data settings, when a repeatedly measured binary response is rare, an ODS design can be highly efficient for maximizing statistical information subject to resource limitations that prohibit covariate ascertainment of all observations. This manuscript details an ODS design where individual observations are sampled with probabilities determined by an inexpensive, time-varying auxiliary variable that is related but is not equal to the response. With the goal of validly estimating marginal model parameters based on the resulting biased sample, we propose a semi-parametric, sequential offsetted logistic regressions (SOLR) approach. The SOLR strategy first estimates the relationship between the auxiliary variable and the response and covariate data by using an offsetted logistic regression analysis where the offset is used to adjust for the biased design. Results from the auxiliary variable model are then combined with the known or estimated sampling probabilities to formulate a second offset that is used to correct for the biased design in the ultimate target model relating the longitudinal binary response to covariates. Because the target model offset is estimated with SOLR, we detail asymptotic standard error estimates that account for uncertainty associated with the auxiliary variable model. Motivated by an analysis of the BioCycle Study (Gaskins et al., Effect of daily fiber intake on reproductive function: the BioCycle Study. American Journal of Clinical Nutrition 2009; 90(4): 1061–1069) that aims to describe the relationship between reproductive health (determined by luteinizing hormone levels) and fiber consumption, we examine properties of SOLR estimators and compare them with other common approaches. PMID:22086716

  8. Demographic models reveal the shape of density dependence for a specialist insect herbivore on variable host plants.

    PubMed

    Miller, Tom E X

    2007-07-01

    1. It is widely accepted that density-dependent processes play an important role in most natural populations. However, persistent challenges in our understanding of density-dependent population dynamics include evaluating the shape of the relationship between density and demographic rates (linear, concave, convex), and identifying extrinsic factors that can mediate this relationship. 2. I studied the population dynamics of the cactus bug Narnia pallidicornis on host plants (Opuntia imbricata) that varied naturally in relative reproductive effort (RRE, the proportion of meristems allocated to reproduction), an important plant quality trait. I manipulated per-plant cactus bug densities, quantified subsequent dynamics, and fit stage-structured models to the experimental data to ask if and how density influences demographic parameters. 3. In the field experiment, I found that populations with variable starting densities quickly converged upon similar growth trajectories. In the model-fitting analyses, the data strongly supported a model that defined the juvenile cactus bug retention parameter (joint probability of surviving and not dispersing) as a nonlinear decreasing function of density. The estimated shape of this relationship shifted from concave to convex with increasing host-plant RRE. 4. The results demonstrate that host-plant traits are critical sources of variation in the strength and shape of density dependence in insects, and highlight the utility of integrated experimental-theoretical approaches for identifying processes underlying patterns of change in natural populations.

  9. Using rain-on-snow events to evaluate the quality of bias correction to represent complex inter-variable dependencies

    NASA Astrophysics Data System (ADS)

    Rössler, Ole; Bosshard, Thomas; Weingartner, Rolf

    2016-04-01

    A key issue for adaptation planning is the information of projections about changes of extremes. Climate projections of meteorological extremes and their downscaling are a challenge on their own. Yet - at least in hydrology - meteorological extremes are not necessarily hydrological extremes. These can also result from a sequence of days with only moderate meteorological conditions, too. This sequences are called "storylines". In climate change impact assess studies it is relevant to know, whether these meteorological storylines are represented in regional climate models, and how well can bias correction preserve or improve the representation. One storyline leading to hydrological extremes are rain-on-snow events, and more specifically rain-on-snowfall events. These events challenge the regional climate model and the bias correction in terms of representing absolute values and inter-variable dependences. This study makes use of the rain-on-snow-storylines to evaluate the performance of regional climate models and a bias correction method in reproducing complex inter-variable dependencies. At first, we applied a hydrological model to a mesoscale catchment in Switzerland that is known to be effected by rain-on-snow events. At second, the ERA-Interim driven regional climate model RCA4.5 - developed at SMHI - with a spatial resolution of 0.11 * 0.11 degree was used to drive the hydrological model. At third, bias-correction of the RCM was done applying the distribution based scaling (DBS) bias-correction method (Yang et al., 2010) developed at the SMHI. The bias-corrected data then also served as driving input data to the hydrological model. Based on the simulated runoff, as well as simulated precipitation, temperature, and snow pack data, an algorithm to detect rain-on-snow events was applied. Finally, the presence or absents of rain-on-snow events for the three different climate input data, ERA.RCA4.5, DBS corrected ERA.RC4 and observed climate, are evaluated within

  10. Variability in Ozone in the Tropical Upper Troposphere-Lower Stratosphere from the 1998-2000 SHADOZ (Southern Hemisphere Additional Ozonesondes) Data

    NASA Technical Reports Server (NTRS)

    Thompson, A. M.; Witte, J. C.; McPeters, R. D.; Schmidlin, F. J.; Oltmans, S. J.; Kirchhoff, V. W. J. H.; Coetzee, G. J. R.; Posny, F.; Kawakami, S.; Ogawa, T.; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    The first view of lower stratospheric and upper tropospheric structure from sondes is provided by a 3-year, 10-site record from the Southern Hemisphere ADditional OZonesondes (SHADOZ) network: . Observations covering 1998-2000 were made over Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil. Taking the UT/LS (upper troposphere- lower stratosphere) as the region between 12 and 17 km, we examine ozone variability in this region on a week-to-week and seasonal basis. The tropopause is lower in September-October-November than in March-April-May, when ozone is a minimum at most SHADOZ stations. A zonal wave-one pattern (referring to ozone mixing ratios greater over the Atlantic and adjacent continents than over the Pacific and eastern Indian Ocean), persists all year. The wave, predominantly in the troposphere and with variable magnitude, appears to be due to general circulation - with subsidence over the Atlantic and frequent deep convection over the Pacific and Indian Ocean. The variability of deep convection most prominent at Java, Fiji, Samoa and Natal - is explored in time-vs-altitude ozone curtains. Stratospheric incursions into the troposphere are most prominent in soundings at Irene and Reunion Island.

  11. Variability in Ozone in the Tropical Upper Troposphere-Lower Stratosphere from the 1998 - 200 SHADOZ (Southern Hemisphere ADditional Ozonesondes) Data

    NASA Astrophysics Data System (ADS)

    Thompson, A.; Witte, J.; Oltmans, S.; Coetzee, G.; Kawakami, S.; Ogawa, T.

    The first view of lower stratospheric and upper tropospheric structure from sondes is provided by a 3 year, 10-site record from the Southern Hemisphere ADditional- OZonesondes (SHADOZ) network: . Observations covering 1998-2000 were made over Ascension Island; Nairobi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Crist"bal, Galapagos; Natal, Brazil. Taking the UT/LS (upper troposphere-lower stratosphere) as the region between 12 and 17 km, we examine ozone variability in this region on a week- to- week and seasonal basis. The tropopause is lower in September-October-November than in March-April- May, when ozone is a minimum at most SHADOZ stations. A zonal wave-one pattern (referring to ozone mixing ratios greater over the Atlantic and adjacent continents than over the Pacific and eastern Indian Ocean), persists all year. The wave, predominantly in the troposphere and with variable magnitude, appears to be due to general circulation - with subsidence over the Atlantic and frequent deep convection over the Pacific and Indian Ocean. The variability of deep convection - most prominent at Java, Fiji, Samoa and Natal - is explored in time-vs-altitude ozone curtains. Stratospheric incursions into the troposphere are most prominent in soundings at Irene and Reunion Island.

  12. Resistor capacitor, primitive variable solution of buoyant fluid flow within an enclosure with highly temperature dependent viscosity

    SciTech Connect

    Burns, S.P.; Gianoulakis, S.E.

    1995-07-01

    A numerical solution for buoyant natural convection within a square enclosure containing a fluid with highly temperature dependent viscosity is presented. Although the fluid properties employed do not represent any real fluid, the large variation in the fluid viscosity with temperature is characteristic of turbulent flow modeling with eddy-viscosity concepts. Results are obtained using a primitive variable formulation and the resistor method. The results presented include velocity, temperature and pressure distributions within the enclosure as well as shear stress and heat flux distributions along the enclosure walls. Three mesh refinements were employed and uncertainty values are suggested for the final mesh refinement. These solutions are part of a contributed benchmark solution set for the subject problem.

  13. Low frequency noise variability in ultra scaled FD-SOI n-MOSFETs: Dependence on gate bias, frequency and temperature

    NASA Astrophysics Data System (ADS)

    Theodorou, C. G.; Ioannidis, E. G.; Haendler, S.; Josse, E.; Dimitriadis, C. A.; Ghibaudo, G.

    2016-03-01

    In this paper, a parametric statistical analysis of the low-frequency noise (LFN) in very small area (W·L ≈ 10-3 μm2) 14 nm fully depleted silicon-on-insulator (FD-SOI) n-MOS devices is presented. It has been demonstrated that the LFN origin is due to carrier trapping/detrapping into gate dielectric traps near the interface and the mean noise level in such small area MOSFETs is well approached by the carrier number fluctuations model in all measurement conditions. The impact of gate voltage bias and temperature on the LFN variability, as well as the standard deviation dependence on frequency have been studied for the first time, focusing on their relation to the Random Telegraph Noise (RTN) effect and its characteristics.

  14. High interindividual variability in dose-dependent reduction in speed of movement after exposing C. elegans to shock waves.

    PubMed

    Angstman, Nicholas B; Kiessling, Maren C; Frank, Hans-Georg; Schmitz, Christoph

    2015-01-01

    In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI. PMID:25705183

  15. High interindividual variability in dose-dependent reduction in speed of movement after exposing C. elegans to shock waves

    PubMed Central

    Angstman, Nicholas B.; Kiessling, Maren C.; Frank, Hans-Georg; Schmitz, Christoph

    2015-01-01

    In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI. PMID:25705183

  16. Polymyxin Resistance of Pseudomonas aeruginosa phoQ Mutants Is Dependent on Additional Two-Component Regulatory Systems

    PubMed Central

    Gutu, Alina D.; Sgambati, Nicole; Strasbourger, Pnina; Brannon, Mark K.; Jacobs, Michael A.; Haugen, Eric; Kaul, Rajinder K.; Johansen, Helle Krogh; Høiby, Niels

    2013-01-01

    Pseudomonas aeruginosa can develop resistance to polymyxin as a consequence of mutations in the PhoPQ regulatory system, mediated by covalent lipid A modification. Transposon mutagenesis of a polymyxin-resistant phoQ mutant defined 41 novel loci required for resistance, including two regulatory systems, ColRS and CprRS. Deletion of the colRS genes, individually or in tandem, abrogated the polymyxin resistance of a ΔphoQ mutant, as did individual or tandem deletion of cprRS. Individual deletion of colR or colS in a ΔphoQ mutant also suppressed 4-amino-l-arabinose addition to lipid A, consistent with the known role of this modification in polymyxin resistance. Surprisingly, tandem deletion of colRS or cprRS in the ΔphoQ mutant or individual deletion of cprR or cprS failed to suppress 4-amino-l-arabinose addition to lipid A, indicating that this modification alone is not sufficient for PhoPQ-mediated polymyxin resistance in P. aeruginosa. Episomal expression of colRS or cprRS in tandem or of cprR individually complemented the Pm resistance phenotype in the ΔphoQ mutant, while episomal expression of colR, colS, or cprS individually did not. Highly polymyxin-resistant phoQ mutants of P. aeruginosa isolated from polymyxin-treated cystic fibrosis patients harbored mutant alleles of colRS and cprS; when expressed in a ΔphoQ background, these mutant alleles enhanced polymyxin resistance. These results define ColRS and CprRS as two-component systems regulating polymyxin resistance in P. aeruginosa, indicate that addition of 4-amino-l-arabinose to lipid A is not the only PhoPQ-regulated biochemical mechanism required for resistance, and demonstrate that colRS and cprS mutations can contribute to high-level clinical resistance. PMID:23459479

  17. Statistical Frequency-Dependent Analysis of Trial-to-Trial Variability in Single Time Series by Recurrence Plots

    PubMed Central

    Tošić, Tamara; Sellers, Kristin K.; Fröhlich, Flavio; Fedotenkova, Mariia; beim Graben, Peter; Hutt, Axel

    2016-01-01

    For decades, research in neuroscience has supported the hypothesis that brain dynamics exhibits recurrent metastable states connected by transients, which together encode fundamental neural information processing. To understand the system's dynamics it is important to detect such recurrence domains, but it is challenging to extract them from experimental neuroscience datasets due to the large trial-to-trial variability. The proposed methodology extracts recurrent metastable states in univariate time series by transforming datasets into their time-frequency representations and computing recurrence plots based on instantaneous spectral power values in various frequency bands. Additionally, a new statistical inference analysis compares different trial recurrence plots with corresponding surrogates to obtain statistically significant recurrent structures. This combination of methods is validated by applying it to two artificial datasets. In a final study of visually-evoked Local Field Potentials in partially anesthetized ferrets, the methodology is able to reveal recurrence structures of neural responses with trial-to-trial variability. Focusing on different frequency bands, the δ-band activity is much less recurrent than α-band activity. Moreover, α-activity is susceptible to pre-stimuli, while δ-activity is much less sensitive to pre-stimuli. This difference in recurrence structures in different frequency bands indicates diverse underlying information processing steps in the brain. PMID:26834580

  18. Space Takes Time: Concentration Dependent Output Codes from Primary Olfactory Networks Rapidly Provide Additional Information at Defined Discrimination Thresholds.

    PubMed

    Daly, Kevin C; Bradley, Samual; Chapman, Phillip D; Staudacher, Erich M; Tiede, Regina; Schachtner, Joachim

    2015-01-01

    As odor concentration increases, primary olfactory network representations expand in spatial distribution, temporal complexity and duration. However, the direct relationship between concentration dependent odor representations and the psychophysical thresholds of detection and discrimination is poorly understood. This relationship is absolutely critical as thresholds signify transition points whereby representations become meaningful to the organism. Here, we matched stimulus protocols for psychophysical assays and intracellular recordings of antennal lobe (AL) projection neurons (PNs) in the moth Manduca sexta to directly compare psychophysical thresholds and the output representations they elicit. We first behaviorally identified odor detection and discrimination thresholds across an odor dilution series for a panel of structurally similar odors. We then characterized spatiotemporal spiking patterns across a population of individually filled and identified AL PNs in response to those odors at concentrations below, at, and above identified thresholds. Using spatial and spatiotemporal based analyses we observed that each stimulus produced unique representations, even at sub-threshold concentrations. Mean response latency did not decrease and the percent glomerular activation did not increase with concentration until undiluted odor. Furthermore, correlations between spatial patterns for odor decreased, but only significantly with undiluted odor. Using time-integrated Euclidean distance (ED) measures, we determined that added spatiotemporal information was present at the discrimination but not detection threshold. This added information was evidenced by an increase in integrated distance between the sub-detection and discrimination threshold concentrations (of the same odor) that was not present in comparison of the sub-detection and detection threshold. After consideration of delays for information to reach the AL we find that it takes ~120-140 ms for the AL to

  19. Space Takes Time: Concentration Dependent Output Codes from Primary Olfactory Networks Rapidly Provide Additional Information at Defined Discrimination Thresholds

    PubMed Central

    Daly, Kevin C.; Bradley, Samual; Chapman, Phillip D.; Staudacher, Erich M.; Tiede, Regina; Schachtner, Joachim

    2016-01-01

    As odor concentration increases, primary olfactory network representations expand in spatial distribution, temporal complexity and duration. However, the direct relationship between concentration dependent odor representations and the psychophysical thresholds of detection and discrimination is poorly understood. This relationship is absolutely critical as thresholds signify transition points whereby representations become meaningful to the organism. Here, we matched stimulus protocols for psychophysical assays and intracellular recordings of antennal lobe (AL) projection neurons (PNs) in the moth Manduca sexta to directly compare psychophysical thresholds and the output representations they elicit. We first behaviorally identified odor detection and discrimination thresholds across an odor dilution series for a panel of structurally similar odors. We then characterized spatiotemporal spiking patterns across a population of individually filled and identified AL PNs in response to those odors at concentrations below, at, and above identified thresholds. Using spatial and spatiotemporal based analyses we observed that each stimulus produced unique representations, even at sub-threshold concentrations. Mean response latency did not decrease and the percent glomerular activation did not increase with concentration until undiluted odor. Furthermore, correlations between spatial patterns for odor decreased, but only significantly with undiluted odor. Using time-integrated Euclidean distance (ED) measures, we determined that added spatiotemporal information was present at the discrimination but not detection threshold. This added information was evidenced by an increase in integrated distance between the sub-detection and discrimination threshold concentrations (of the same odor) that was not present in comparison of the sub-detection and detection threshold. After consideration of delays for information to reach the AL we find that it takes ~120–140 ms for the AL to

  20. Modeling of time dependent localized flow shear stress and its impact on cellular growth within additive manufactured titanium implants.

    PubMed

    Zhang, Ziyu; Yuan, Lang; Lee, Peter D; Jones, Eric; Jones, Julian R

    2014-11-01

    Bone augmentation implants are porous to allow cellular growth, bone formation and fixation. However, the design of the pores is currently based on simple empirical rules, such as minimum pore and interconnects sizes. We present a three-dimensional (3D) transient model of cellular growth based on the Navier-Stokes equations that simulates the body fluid flow and stimulation of bone precursor cellular growth, attachment, and proliferation as a function of local flow shear stress. The model's effectiveness is demonstrated for two additive manufactured (AM) titanium scaffold architectures. The results demonstrate that there is a complex interaction of flow rate and strut architecture, resulting in partially randomized structures having a preferential impact on stimulating cell migration in 3D porous structures for higher flow rates. This novel result demonstrates the potential new insights that can be gained via the modeling tool developed, and how the model can be used to perform what-if simulations to design AM structures to specific functional requirements.

  1. The impact of clinical and demographic variables on cognitive performance in methamphetamine-dependent individuals in rural South Carolina.

    PubMed

    Price, Kimber L; DeSantis, Stacia M; Simpson, Annie N; Tolliver, Bryan K; McRae-Clark, Aimee L; Saladin, Michael E; Baker, Nathaniel L; Wagner, Mark T; Brady, Kathleen T

    2011-01-01

    Inconsistencies in reports on methamphetamine (METH) associated cognitive dysfunction may be attributed, at least in part, to the diversity of study sample features (eg, clinical and demographic characteristics). The current study assessed cognitive function in a METH-dependent population from rural South Carolina, and the impact of demographic and clinical characteristics on performance. Seventy-one male (28.2%) and female (71.8%) METH-dependent subjects were administered a battery of neurocognitive tests including the Test of Memory Malingering (TOMM), Shipley Institute of Living Scale, Paced Auditory Serial Addition Test (PASAT), Symbol Digit Modalities Test (SDMT), Grooved Pegboard Test, California Verbal Learning Test (CVLT), and Wisconsin Card Sorting Test (WCST). Demographic and clinical characteristics (eg, gender, frequency of METH use) were examined as predictors of performance. Subjects scored significantly lower than expected on one test of attention and one of fine motor function, but performed adequately on all other tests. There were no predictors of performance on attention; however, more frequent METH use was associated with better performance for males and worse for females on fine motor skills. The METH-dependent individuals in this population exhibit very limited cognitive impairment. The marked differences in education, Intellectual Quotient (IQ), and gender in our sample when compared to the published literature may contribute to these findings. Characterization of the impact of clinical and/or demographic features on cognitive deficits could be important in guiding the development of treatment interventions.

  2. Self-Produced Time Intervals Are Perceived as More Variable and/or Shorter Depending on Temporal Context in Subsecond and Suprasecond Ranges

    PubMed Central

    Mitani, Keita; Kashino, Makio

    2016-01-01

    The processing of time intervals is fundamental for sensorimotor and cognitive functions. Perceptual and motor timing are often performed concurrently (e.g., playing a musical instrument). Although previous studies have shown the influence of body movements on time perception, how we perceive self-produced time intervals has remained unclear. Furthermore, it has been suggested that the timing mechanisms are distinct for the sub- and suprasecond ranges. Here, we compared perceptual performances for self-produced and passively presented time intervals in random contexts (i.e., multiple target intervals presented in a session) across the sub- and suprasecond ranges (Experiment 1) and within the sub- (Experiment 2) and suprasecond (Experiment 3) ranges, and in a constant context (i.e., a single target interval presented in a session) in the sub- and suprasecond ranges (Experiment 4). We show that self-produced time intervals were perceived as shorter and more variable across the sub- and suprasecond ranges and within the suprasecond range but not within the subsecond range in a random context. In a constant context, the self-produced time intervals were perceived as more variable in the suprasecond range but not in the subsecond range. The impairing effects indicate that motor timing interferes with perceptual timing. The dependence of impairment on temporal contexts suggests multiple timing mechanisms for the subsecond and suprasecond ranges. In addition, violation of the scalar property (i.e., a constant variability to target interval ratio) was observed between the sub- and suprasecond ranges. The violation was clearer for motor timing than for perceptual timing. This suggests that the multiple timing mechanisms for the sub- and suprasecond ranges overlap more for perception than for motor. Moreover, the central tendency effect (i.e., where shorter base intervals are overestimated and longer base intervals are underestimated) disappeared with motor timing within the

  3. Self-Produced Time Intervals Are Perceived as More Variable and/or Shorter Depending on Temporal Context in Subsecond and Suprasecond Ranges.

    PubMed

    Mitani, Keita; Kashino, Makio

    2016-01-01

    The processing of time intervals is fundamental for sensorimotor and cognitive functions. Perceptual and motor timing are often performed concurrently (e.g., playing a musical instrument). Although previous studies have shown the influence of body movements on time perception, how we perceive self-produced time intervals has remained unclear. Furthermore, it has been suggested that the timing mechanisms are distinct for the sub- and suprasecond ranges. Here, we compared perceptual performances for self-produced and passively presented time intervals in random contexts (i.e., multiple target intervals presented in a session) across the sub- and suprasecond ranges (Experiment 1) and within the sub- (Experiment 2) and suprasecond (Experiment 3) ranges, and in a constant context (i.e., a single target interval presented in a session) in the sub- and suprasecond ranges (Experiment 4). We show that self-produced time intervals were perceived as shorter and more variable across the sub- and suprasecond ranges and within the suprasecond range but not within the subsecond range in a random context. In a constant context, the self-produced time intervals were perceived as more variable in the suprasecond range but not in the subsecond range. The impairing effects indicate that motor timing interferes with perceptual timing. The dependence of impairment on temporal contexts suggests multiple timing mechanisms for the subsecond and suprasecond ranges. In addition, violation of the scalar property (i.e., a constant variability to target interval ratio) was observed between the sub- and suprasecond ranges. The violation was clearer for motor timing than for perceptual timing. This suggests that the multiple timing mechanisms for the sub- and suprasecond ranges overlap more for perception than for motor. Moreover, the central tendency effect (i.e., where shorter base intervals are overestimated and longer base intervals are underestimated) disappeared with motor timing within the

  4. Inference for binomial probability based on dependent Bernoulli random variables with applications to meta-analysis and group level studies.

    PubMed

    Bakbergenuly, Ilyas; Kulinskaya, Elena; Morgenthaler, Stephan

    2016-07-01

    We study bias arising as a result of nonlinear transformations of random variables in random or mixed effects models and its effect on inference in group-level studies or in meta-analysis. The findings are illustrated on the example of overdispersed binomial distributions, where we demonstrate considerable biases arising from standard log-odds and arcsine transformations of the estimated probability p̂, both for single-group studies and in combining results from several groups or studies in meta-analysis. Our simulations confirm that these biases are linear in ρ, for small values of ρ, the intracluster correlation coefficient. These biases do not depend on the sample sizes or the number of studies K in a meta-analysis and result in abysmal coverage of the combined effect for large K. We also propose bias-correction for the arcsine transformation. Our simulations demonstrate that this bias-correction works well for small values of the intraclass correlation. The methods are applied to two examples of meta-analyses of prevalence. PMID:27192062

  5. Inference for binomial probability based on dependent Bernoulli random variables with applications to meta‐analysis and group level studies

    PubMed Central

    Bakbergenuly, Ilyas; Morgenthaler, Stephan

    2016-01-01

    We study bias arising as a result of nonlinear transformations of random variables in random or mixed effects models and its effect on inference in group‐level studies or in meta‐analysis. The findings are illustrated on the example of overdispersed binomial distributions, where we demonstrate considerable biases arising from standard log‐odds and arcsine transformations of the estimated probability p^, both for single‐group studies and in combining results from several groups or studies in meta‐analysis. Our simulations confirm that these biases are linear in ρ, for small values of ρ, the intracluster correlation coefficient. These biases do not depend on the sample sizes or the number of studies K in a meta‐analysis and result in abysmal coverage of the combined effect for large K. We also propose bias‐correction for the arcsine transformation. Our simulations demonstrate that this bias‐correction works well for small values of the intraclass correlation. The methods are applied to two examples of meta‐analyses of prevalence. PMID:27192062

  6. Bayesian adjustment for the misclassification in both dependent and independent variables with application to a breast cancer study.

    PubMed

    Liu, Juxin; Gustafson, Paul; Huo, Dezheng

    2016-10-15

    In this paper, we propose a Bayesian method to address misclassification errors in both independent and dependent variables. Our work is motivated by a study of women who have experienced new breast cancers on two separate occasions. We call both cancers primary, because the second is usually not considered as the result of a metastasis spreading from the first. Hormone receptors (HRs) are important in breast cancer biology, and it is well recognized that the measurement of HR status is subject to errors. This discordance in HR status for two primary breast cancers is of concern and might be an important reason for treatment failure. To sort out the information on true concordance rate from the observed concordance rate, we consider a logistic regression model for the association between the HR status of the two cancers and introduce the misclassification parameters (i.e., sensitivity and specificity) accounting for the misclassification in HR status. The prior distribution for sensitivity and specificity is based on how HR status is actually assessed in laboratory procedures. To account for the nonlinear effect of one error-free covariate, we introduce the B-spline terms in the logistic regression model. Our findings indicate that the true concordance rate of HR status between two primary cancers is greater than the observed value. Copyright © 2016 John Wiley & Sons, Ltd.

  7. Oxygen-Dependent Cell-to-Cell Variability in the Output of the Escherichia coli Tor Phosphorelay

    PubMed Central

    Roggiani, Manuela

    2015-01-01

    ABSTRACT Escherichia coli senses and responds to trimethylamine-N-oxide (TMAO) in the environment through the TorT-TorS-TorR signal transduction system. The periplasmic protein TorT binds TMAO and stimulates the hybrid kinase TorS to phosphorylate the response regulator TorR through a phosphorelay. Phosphorylated TorR, in turn, activates transcription of the torCAD operon, which encodes the proteins required for anaerobic respiration via reduction of TMAO to trimethylamine. Interestingly, E. coli respires TMAO in both the presence and absence of oxygen, a behavior that is markedly different from the utilization of other alternative electron acceptors by this bacterium. Here we describe an unusual form of regulation by oxygen for this system. While the average level of torCAD transcription is the same for aerobic and anaerobic cultures containing TMAO, the behavior across the population of cells is strikingly different under the two growth conditions. Cellular levels of torCAD transcription in aerobic cultures are highly heterogeneous, in contrast to the relatively homogeneous distribution in anaerobic cultures. Thus, oxygen regulates the variance of the output but not the mean for the Tor system. We further show that this oxygen-dependent variability stems from the phosphorelay. IMPORTANCE Trimethylamine-N-oxide (TMAO) is utilized by numerous bacteria as an electron acceptor for anaerobic respiration. In E. coli, expression of the proteins required for TMAO respiration is tightly regulated by a signal transduction system that is activated by TMAO. Curiously, although oxygen is the energetically preferred electron acceptor, TMAO is respired even in the presence of oxygen. Here we describe an interesting and unexpected form of regulation for this system in which oxygen produces highly variable expression of the TMAO utilization proteins across a population of cells without affecting the mean expression of these proteins. To our knowledge, this is the first reported

  8. Heart Rate Variability for Early Detection of Cardiac Iron Deposition in Patients with Transfusion-Dependent Thalassemia

    PubMed Central

    Silvilairat, Suchaya; Charoenkwan, Pimlak; Saekho, Suwit; Tantiworawit, Adisak; Phrommintikul, Arintaya; Srichairatanakool, Somdet; Chattipakorn, Nipon

    2016-01-01

    Background Iron overload cardiomyopathy remains the major cause of death in patients with transfusion-dependent thalassemia. Cardiac T2* magnetic resonance imaging is costly yet effective in detecting cardiac iron accumulation in the heart. Heart rate variability (HRV) has been used to evaluate cardiac autonomic function and is depressed in cases of thalassemia. We evaluated whether HRV could be used as an indicator for early identification of cardiac iron deposition. Methods One hundred and one patients with transfusion-dependent thalassemia were enrolled in this study. The correlation between recorded HRV and hemoglobin, non-transferrin bound iron (NTBI), serum ferritin and cardiac T2* were evaluated. Results The median age was 18 years (range 8–59 years). The patient group with a 5-year mean serum ferritin >5,000 ng/mL included significantly more homozygous β-thalassemia and splenectomized patients, had lower hemoglobin levels, and had more cardiac iron deposit than all other groups. Anemia strongly influenced all domains of HRV. After adjusting for anemia, neither serum ferritin nor NTBI impacted the HRV. However cardiac T2* was an independent predictor of HRV, even after adjusting for anemia. For receiver operative characteristic (ROC) curve analysis of cardiac T2* ≤20 ms, only mean ferritin in the last 12 months and the average of the standard deviation of all R-R intervals for all five-minute segments in the 24-hour recording were predictors for cardiac T2* ≤20 ms, with area under the ROC curve of 0.961 (p<0.0001) and 0.701 (p = 0.05), respectively. Conclusions Hemoglobin and cardiac T2* as significant predictors for HRV indicate that anemia and cardiac iron deposition result in cardiac autonomic imbalance. The mean ferritin in the last 12 months could be useful as the best indicator for further evaluation of cardiac risk. The ability of serum ferritin to predict cardiac risk is stronger than observed in other thalassemia cohorts. HRV might be a

  9. Quantification of Cholesterol Solubilized in Dietary Micelles: Dependence on Human Bile Salt Variability and the Presence of Dietary Food Ingredients.

    PubMed

    Coreta-Gomes, Filipe M; Vaz, Winchil L C; Wasielewski, Emeric; Geraldes, Carlos F G; Moreno, Maria João

    2016-05-10

    The solubility of cholesterol in bile salt (BS) micelles is important to understand the availability of cholesterol for absorption in the intestinal epithelium and to develop strategies to decrease cholesterol intake from the intestinal lumen. This has been the subject of intense investigation, due to the established relation between the development of diseases such as atherosclerosis and high levels of cholesterol in the blood. In this work we quantify the effect of BS variability on the amount of cholesterol solubilized. The effect of some known hypocholesterolemic agents usually found in the diet is also evaluated, as well as some insight regarding the mechanisms involved. The results show that, depending on the bile salt composition, the average value of sterol per micelle is equal to or lower than 1. The amount of cholesterol solubilized in the BS micelles is essentially equal to its total concentration until the solubility limit is reached. Altogether, this indicates that the maximum cholesterol solubility in the BS micellar solution is the result of saturation of the aqueous phase and depends on the partition coefficient of cholesterol between the aqueous phase and the micellar pseudophase. The effect on cholesterol maximum solubility for several food ingredients usually encountered in the diet was characterized using methodology developed recently by us. This method allows the simultaneous quantification of both cholesterol and food ingredient solubilized in the BS micelles even in the presence of larger aggregates, therefore avoiding their physical separation with possible impacts on the overall equilibrium. The phytosterols stigmasterol and stigmastanol significantly decreased cholesterol solubility with a concomitant reduction in the total amount of sterol solubilized, most pronounced for stigmasterol. Those results point toward coprecipitation being the major cause for the decrease in cholesterol solubilization by the BS micelles. The presence of

  10. The 1998-2000 SHADOZ (Southern Hemisphere ADditional OZonesondes) Tropical Ozone Climatology. 2; Stratospheric and Tropospheric Ozone Variability and the Zonal Wave-One

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Schmidlin, Francis J.; Logan, Jennifer A.; Fujiwara, Masatomo; Kirchhoff, Volker W. J. H.; Posny, Francoise; Coetzee, Gert J. R.; Hoegger, Bruno; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    This is the second 'reference' or 'archival' paper for the SHADOZ (Southern Hemisphere Additional Ozonesondes) network and is a follow-on to the recently accepted paper with similar first part of title. The latter paper compared SHADOZ total ozone with satellite and ground-based instruments and showed that the equatorial wave-one in total ozone is in the troposphere. The current paper presents details of the wave-one structure and the first overview of tropospheric ozone variability over the southern Atlantic, Pacific and Indian Ocean basins. The principal new result is that signals of climate effects, convection and offsets between biomass burning seasonality and tropospheric ozone maxima suggest that dynamical factors are perhaps more important than pollution in determining the tropical distribution of tropospheric ozone. The SHADOZ data at () are setting records in website visits and are the first time that the zonal view of tropical ozone structure has been recorded - thanks to the distribution of the 10 sites that make up this validation network.

  11. The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: a generalized additive mixed model.

    PubMed

    Weltz, Kay; Kock, Alison A; Winker, Henning; Attwood, Colin; Sikweyiya, Monwabisi

    2013-01-01

    Shark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters, recorded 378 white shark (Carcharodon carcharias) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14 °C and approached a maximum at 18 °C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18 °C than at 14 °C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town. PMID:23874668

  12. The influence of environmental variables on the presence of white sharks, Carcharodon carcharias at two popular Cape Town bathing beaches: a generalized additive mixed model.

    PubMed

    Weltz, Kay; Kock, Alison A; Winker, Henning; Attwood, Colin; Sikweyiya, Monwabisi

    2013-01-01

    Shark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters, recorded 378 white shark (Carcharodon carcharias) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14 °C and approached a maximum at 18 °C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18 °C than at 14 °C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town.

  13. The Influence of Environmental Variables on the Presence of White Sharks, Carcharodon carcharias at Two Popular Cape Town Bathing Beaches: A Generalized Additive Mixed Model

    PubMed Central

    Weltz, Kay; Kock, Alison A.; Winker, Henning; Attwood, Colin; Sikweyiya, Monwabisi

    2013-01-01

    Shark attacks on humans are high profile events which can significantly influence policies related to the coastal zone. A shark warning system in South Africa, Shark Spotters, recorded 378 white shark (Carcharodon carcharias) sightings at two popular beaches, Fish Hoek and Muizenberg, during 3690 six-hour long spotting shifts, during the months September to May 2006 to 2011. The probabilities of shark sightings were related to environmental variables using Binomial Generalized Additive Mixed Models (GAMMs). Sea surface temperature was significant, with the probability of shark sightings increasing rapidly as SST exceeded 14°C and approached a maximum at 18°C, whereafter it remains high. An 8 times (Muizenberg) and 5 times (Fish Hoek) greater likelihood of sighting a shark was predicted at 18°C than at 14°C. Lunar phase was also significant with a prediction of 1.5 times (Muizenberg) and 4 times (Fish Hoek) greater likelihood of a shark sighting at new moon than at full moon. At Fish Hoek, the probability of sighting a shark was 1.6 times higher during the afternoon shift compared to the morning shift, but no diel effect was found at Muizenberg. A significant increase in the number of shark sightings was identified over the last three years, highlighting the need for ongoing research into shark attack mitigation. These patterns will be incorporated into shark awareness and bather safety campaigns in Cape Town. PMID:23874668

  14. Mechanism Underlying Time-dependent Cross-phenomenon between Concentration-response Curves and Concentration Addition Curves: A Case Study of Sulfonamides-Erythromycin mixtures on Escherichia coli

    NASA Astrophysics Data System (ADS)

    Sun, Haoyu; Ge, Hongming; Zheng, Min; Lin, Zhifen; Liu, Ying

    2016-09-01

    Previous studies have identified a phenomenon in which the concentration-response curves (CRCs) for mixtures cross the curves for concentration addition model when predicting or judging joint toxic actions. However, mechanistic investigations of this phenomenon are extremely limited. In this study, a similar phenomenon was observed when we determined the joint toxic actions of sulfonamides (SAs) and erythromycin (ERY) on Escherichia coli (E. coli), which we named the “cross-phenomenon”, and it was characterized by antagonism in the low-concentration range, addition in the medium-concentration range, and synergism in the high-concentration range. The mechanistic investigation of the cross-phenomenon was as follows: SAs and ERY could form a double block to inhibit the bacterial growth by exhibiting a synergistic effect; however, the hormetic effect of SAs on E. coli led to antagonism in the low-concentration range, resulting from the stimulation of sdiA mRNA expression by SAs, which increased the expression of the efflux pump (AcrAB-TolC) to discharge ERY. Furthermore, this cross-phenomenon was observed to be a time-dependent process induced by the increase of both the concentration and extent of stimulation of sdiA mRNA with exposure time. This work explains the dose-dependent and time-dependent cross-phenomenon and provides evidence regarding the interaction between hormesis and cross-phenomenon.

  15. Mechanism Underlying Time-dependent Cross-phenomenon between Concentration-response Curves and Concentration Addition Curves: A Case Study of Sulfonamides-Erythromycin mixtures on Escherichia coli.

    PubMed

    Sun, Haoyu; Ge, Hongming; Zheng, Min; Lin, Zhifen; Liu, Ying

    2016-01-01

    Previous studies have identified a phenomenon in which the concentration-response curves (CRCs) for mixtures cross the curves for concentration addition model when predicting or judging joint toxic actions. However, mechanistic investigations of this phenomenon are extremely limited. In this study, a similar phenomenon was observed when we determined the joint toxic actions of sulfonamides (SAs) and erythromycin (ERY) on Escherichia coli (E. coli), which we named the "cross-phenomenon", and it was characterized by antagonism in the low-concentration range, addition in the medium-concentration range, and synergism in the high-concentration range. The mechanistic investigation of the cross-phenomenon was as follows: SAs and ERY could form a double block to inhibit the bacterial growth by exhibiting a synergistic effect; however, the hormetic effect of SAs on E. coli led to antagonism in the low-concentration range, resulting from the stimulation of sdiA mRNA expression by SAs, which increased the expression of the efflux pump (AcrAB-TolC) to discharge ERY. Furthermore, this cross-phenomenon was observed to be a time-dependent process induced by the increase of both the concentration and extent of stimulation of sdiA mRNA with exposure time. This work explains the dose-dependent and time-dependent cross-phenomenon and provides evidence regarding the interaction between hormesis and cross-phenomenon. PMID:27644411

  16. Mechanism Underlying Time-dependent Cross-phenomenon between Concentration-response Curves and Concentration Addition Curves: A Case Study of Sulfonamides-Erythromycin mixtures on Escherichia coli

    PubMed Central

    Sun, Haoyu; Ge, Hongming; Zheng, Min; Lin, Zhifen; Liu, Ying

    2016-01-01

    Previous studies have identified a phenomenon in which the concentration-response curves (CRCs) for mixtures cross the curves for concentration addition model when predicting or judging joint toxic actions. However, mechanistic investigations of this phenomenon are extremely limited. In this study, a similar phenomenon was observed when we determined the joint toxic actions of sulfonamides (SAs) and erythromycin (ERY) on Escherichia coli (E. coli), which we named the “cross-phenomenon”, and it was characterized by antagonism in the low-concentration range, addition in the medium-concentration range, and synergism in the high-concentration range. The mechanistic investigation of the cross-phenomenon was as follows: SAs and ERY could form a double block to inhibit the bacterial growth by exhibiting a synergistic effect; however, the hormetic effect of SAs on E. coli led to antagonism in the low-concentration range, resulting from the stimulation of sdiA mRNA expression by SAs, which increased the expression of the efflux pump (AcrAB-TolC) to discharge ERY. Furthermore, this cross-phenomenon was observed to be a time-dependent process induced by the increase of both the concentration and extent of stimulation of sdiA mRNA with exposure time. This work explains the dose-dependent and time-dependent cross-phenomenon and provides evidence regarding the interaction between hormesis and cross-phenomenon. PMID:27644411

  17. Sulfate reduction in sulfuric material after re-flooding: Effectiveness of organic carbon addition and pH increase depends on soil properties.

    PubMed

    Yuan, Chaolei; Fitzpatrick, Rob; Mosley, Luke M; Marschner, Petra

    2015-11-15

    Sulfuric material is formed upon oxidation of sulfidic material; it is extremely acidic, and therefore, an environmental hazard. One option for increasing pH of sulfuric material may be stimulation of bacterial sulfate reduction. We investigated the effects of organic carbon addition and pH increase on sulfate reduction after re-flooding in ten sulfuric materials with four treatments: control, pH increase to 5.5 (+pH), organic carbon addition with 2% w/w finely ground wheat straw (+C), and organic carbon addition and pH increase (+C+pH). After 36 weeks, in five of the ten soils, only treatment +C+pH significantly increased the concentration of reduced inorganic sulfur (RIS) compared to the control and increased the soil pore water pH compared to treatment+pH. In four other soils, pH increase or/and organic carbon addition had no significant effect on RIS concentration compared to the control. The RIS concentration in treatment +C+pH as percentage of the control was negatively correlated with soil clay content and initial nitrate concentration. The results suggest that organic carbon addition and pH increase can stimulate sulfate reduction after re-flooding, but the effectiveness of this treatment depends on soil properties. PMID:26024614

  18. Solvation free energy of the peptide group: its model dependence and implications for the additive-transfer free-energy model of protein stability.

    PubMed

    Tomar, Dheeraj S; Asthagiri, D; Weber, Valéry

    2013-09-17

    The group-additive decomposition of the unfolding free energy of a protein in an osmolyte solution relative to that in water poses a fundamental paradox: whereas the decomposition describes the experimental results rather well, theory suggests that a group-additive decomposition of free energies is, in general, not valid. In a step toward resolving this paradox, here we study the peptide-group transfer free energy. We calculate the vacuum-to-solvent (solvation) free energies of (Gly)n and cyclic diglycine (cGG) and analyze the data according to experimental protocol. The solvation free energies of (Gly)n are linear in n, suggesting group additivity. However, the slope interpreted as the free energy of a peptide unit differs from that for cGG scaled by a factor of half, emphasizing the context dependence of solvation. However, the water-to-osmolyte transfer free energies of the peptide unit are relatively independent of the peptide model, as observed experimentally. To understand these observations, a way to assess the contribution to the solvation free energy of solvent-mediated correlation between distinct groups is developed. We show that linearity of solvation free energy with n is a consequence of uniformity of the correlation contributions, with apparent group-additive behavior in the water-to-osmolyte transfer arising due to their cancellation. Implications for inferring molecular mechanisms of solvent effects on protein stability on the basis of the group-additive transfer model are suggested.

  19. Sulfate reduction in sulfuric material after re-flooding: Effectiveness of organic carbon addition and pH increase depends on soil properties.

    PubMed

    Yuan, Chaolei; Fitzpatrick, Rob; Mosley, Luke M; Marschner, Petra

    2015-11-15

    Sulfuric material is formed upon oxidation of sulfidic material; it is extremely acidic, and therefore, an environmental hazard. One option for increasing pH of sulfuric material may be stimulation of bacterial sulfate reduction. We investigated the effects of organic carbon addition and pH increase on sulfate reduction after re-flooding in ten sulfuric materials with four treatments: control, pH increase to 5.5 (+pH), organic carbon addition with 2% w/w finely ground wheat straw (+C), and organic carbon addition and pH increase (+C+pH). After 36 weeks, in five of the ten soils, only treatment +C+pH significantly increased the concentration of reduced inorganic sulfur (RIS) compared to the control and increased the soil pore water pH compared to treatment+pH. In four other soils, pH increase or/and organic carbon addition had no significant effect on RIS concentration compared to the control. The RIS concentration in treatment +C+pH as percentage of the control was negatively correlated with soil clay content and initial nitrate concentration. The results suggest that organic carbon addition and pH increase can stimulate sulfate reduction after re-flooding, but the effectiveness of this treatment depends on soil properties.

  20. The evolution of earthquake-nucleating slip instabilities under spatially variable steady-state rate dependence of friction

    NASA Astrophysics Data System (ADS)

    Ray, S.; Viesca, R. C.

    2014-12-01

    Following laboratory rock friction experiments, fault strength under sub-seismic slip speeds is thought to depend on a slip rate- and state-dependent friction. Laboratory-measured temperature dependence of the frictional properties and their implied variation with depth form the basis for current models of the seismic cycle. However, scant attention has been paid to the role such heterogeneity has on determining the location and manner in which an earthquake nucleating slip instability develops. Recent work demonstrates that a slip instability on a fault with rate-and-state friction (in which state evolution follows the aging law) occurs as the attraction of a dynamical system towards a fixed point (Viesca, this meeting). Based on this development, we find that the location of that fixed point may be determined if a heterogeneous distribution of the relative rate-weakening parameter a/b is known. (Rate-weakening occurs for 01). That this arises can be deduced considering that (i) the problem that determines the fixed points is equivalent to finding the equilibrium solution for a linearly slip-weakening crack, and (ii) heterogeneities in the parameter a/b have analogy in the equivalent problem to heterogeneities in the background stress. Physically, instability develops where rate-weakening is strongest. We examined the influence such a heterogeneity has on the fixed point attractor (and hence on the instability development) by considering the scenario of a rate-weakening patch embedded within a rate-strengthening region with in-plane or anti-plane slip conditions. Specifically, we solve for fixed points under a rate-weakening heterogeneity within |x|1) outside. Additionally, a linear stability analysis reveals the effect of heterogeneity on the stability of the fixed points of the dynamical system. The heterogeneity parameters (a

  1. An Analysis of Some Variables Affecting the Internet Dependency Level of Turkish Adolescents by Using Decision Tree Methods

    ERIC Educational Resources Information Center

    Kayri, Murat; Gunuc, Selim

    2010-01-01

    Internet dependency is going to expand into social life in wide area whereas it has been accepted as a pathological and psychological disease. Knowing the basic effects of internet dependency is an inevitable approach to use the internet technology healthy. In this study, internet dependency levels of 754 students were examined with the Internet…

  2. Variability in blood oxygen level dependent (BOLD) signal in patients with stroke-induced and primary progressive aphasia.

    PubMed

    Bonakdarpour, B; Beeson, P M; DeMarco, A T; Rapcsak, S Z

    2015-01-01

    Although fMRI is increasingly used to assess language-related brain activation in patients with aphasia, few studies have examined the hemodynamic response function (HRF) in perilesional, and contralesional areas of the brain. In addition, the relationship between HRF abnormalities and other variables such as lesion size and severity of aphasia has not been explored. The objective of this study was to investigate changes in HRF signal during language-related neural activation in patients with stroke-induced aphasia (SA). We also examined the status of the HRF in patients with aphasia due to nonvascular etiology, namely, primary progressive aphasia (PPA). Five right handed SA patients, three PPA patients, and five healthy individuals participated in the study. Structural damage was quantified with T1-weighted MR images. Functional MR imaging was performed with long trial event-related design and an overt naming task to measure BOLD signal time to peak (TTP) and percent signal change (ΔS). In SA patients, the average HRF TTP was significantly delayed in the left hemisphere regions involved in naming compared to healthy participants and PPA patients. However, ΔS was not different in SA patients compared to the other two groups. Delay in HRF TTP in the left hemisphere naming network of SA patients was correlated with lesion size and showed a negative correlation with global language function. There were no significant differences in the HRF TTP and ΔS in the right hemisphere homologues of the naming network or in the left and the right occipital control regions across the three groups. In PPA patients, HRF had a normal pattern. Our results indicate that abnormal task-related HRF is primarily found in the left hemisphere language network of SA patients and raise the possibility that abnormal physiology superimposed on structural damage may contribute to the clinical deficit. Follow-up investigations in a larger sample of age-matched healthy individuals, SA, and PPA

  3. Variability in blood oxygen level dependent (BOLD) signal in patients with stroke-induced and primary progressive aphasia

    PubMed Central

    Bonakdarpour, B.; Beeson, P.M.; DeMarco, A.T.; Rapcsak, S.Z.

    2015-01-01

    Although fMRI is increasingly used to assess language-related brain activation in patients with aphasia, few studies have examined the hemodynamic response function (HRF) in perilesional, and contralesional areas of the brain. In addition, the relationship between HRF abnormalities and other variables such as lesion size and severity of aphasia has not been explored. The objective of this study was to investigate changes in HRF signal during language-related neural activation in patients with stroke-induced aphasia (SA). We also examined the status of the HRF in patients with aphasia due to nonvascular etiology, namely, primary progressive aphasia (PPA). Five right handed SA patients, three PPA patients, and five healthy individuals participated in the study. Structural damage was quantified with T1-weighted MR images. Functional MR imaging was performed with long trial event-related design and an overt naming task to measure BOLD signal time to peak (TTP) and percent signal change (ΔS). In SA patients, the average HRF TTP was significantly delayed in the left hemisphere regions involved in naming compared to healthy participants and PPA patients. However, ΔS was not different in SA patients compared to the other two groups. Delay in HRF TTP in the left hemisphere naming network of SA patients was correlated with lesion size and showed a negative correlation with global language function. There were no significant differences in the HRF TTP and ΔS in the right hemisphere homologues of the naming network or in the left and the right occipital control regions across the three groups. In PPA patients, HRF had a normal pattern. Our results indicate that abnormal task-related HRF is primarily found in the left hemisphere language network of SA patients and raise the possibility that abnormal physiology superimposed on structural damage may contribute to the clinical deficit. Follow-up investigations in a larger sample of age-matched healthy individuals, SA, and PPA

  4. [Personality variables, psychopathological alterations and personality disorders in alcohol-dependent patients according to Cloninger's typology of alcohol abuse].

    PubMed

    Echeburúa, Enrique; Bravo de Medina, Ricardo; Aizpiri, Javier

    2008-11-01

    In this paper, an evaluation of Cloninger's typology of alcohol abuse in personality, psychopathology and personality disorders is carried out. The sample consisted of 158 alcoholics in treatment (56 Type I alcohol-dependent patients and 102 Type II alcohol-dependent patients). All subjects were assessed with diverse assessment tools related to personality (Impulsiveness Scale, Sensation Seeking Scale and STAI), psychopathology (SCL-90-R, BDI and Inadaptation Scale) and personality disorders (IPDE). The main findings were that Type II alcohol-dependent patients were more impulsive and sensation-seeking and they displayed more hostility and emotional distress than Type I alcohol-dependent patients. Personality disorders were not so prevalent in the case of Type I alcohol-dependent patients. The most specific personality disorders for Type II alcohol-dependent patients were narcissistic and paranoid. The implications of this study for further research are commented on.

  5. The combination of trastuzumab and pertuzumab administered at approved doses may delay development of trastuzumab resistance by additively enhancing antibody-dependent cell-mediated cytotoxicity

    PubMed Central

    Tóth, Gábor; Szöőr, Árpád; Simon, László; Yarden, Yosef; Szöllősi, János; Vereb, György

    2016-01-01

    ABSTRACT Although the recently concluded CLEOPATRA trial showed clinical benefits of combining trastuzumab and pertuzumab for treating HER2-positive metastatic breast cancer, trastuzumab monotherapy is still the mainstay in adjuvant settings. Since trastuzumab resistance occurs in over half of these cancers, we examined the mechanisms by which treatment of intrinsically trastuzumab-resistant and -sensitive tumors can benefit from the combination of these antibodies. F(ab′)2 of both trastuzumab and pertuzumab were generated and validated in order to separately analyze antibody-dependent cell-mediated cytotoxicity (ADCC)-based and direct biological effects of the antibodies. Compared to monotherapy, combination of the two antibodies at clinically permitted doses enhanced the recruitment of natural killer cells responsible for ADCC, and significantly delayed the outgrowth of xenografts from intrinsically trastuzumab-resistant JIMT-1 cells. Antibody dose-response curves of in vitro ADCC showed that antibody-mediated killing can be saturated, and the two antibodies exert an additive effect at sub-saturation doses. Thus, the additive effect in vivo indicates that therapeutic tissue levels likely do not saturate ADCC. Additionally, isobole studies with the in vitro trastuzumab-sensitive BT-474 cells showed that the direct biological effect of combined treatment is additive, and surpasses the maximum effect of either monotherapy. Our results suggest the combined therapy is expected to give results that are superior to monotherapy, whatever the type of HER2-positive tumor may be. The combination of both antibodies at maximum clinically approved doses should thus be administered to patients to recruit maximum ADCC and cause maximum direct biological growth inhibition. PMID:27380003

  6. The Association of Program-Related Variables to Length of Sobriety: A Pilot Study of Chemically Dependent Women.

    ERIC Educational Resources Information Center

    Kelly, Virginia A.; And Others

    1995-01-01

    No studies of substance abuse treatment program outcomes specifically related to women and women's programs has been undertaken. In this study of a women's treatment center, variables shown to be related to length of sobriety include active participation in two sections of the program: the aftercare program and vocational/educational training.…

  7. Coupling of nuclear quadrupole and octupole degrees of freedom in an angular momentum dependent potential of two deformation variables

    SciTech Connect

    Minkov, N.; Yotov, P.; Drenska, S.; Scheid, W.; Bonatsos, Dennis; Lenis, D.; Petrellis, D.

    2006-04-26

    We propose a collective rotation-vibration Hamiltonian of nuclei in which the axial quadrupole {beta}2 and octupole {beta}3 variables are coupled through the centrifugal interaction. We consider that the system oscillates between positive and negative {beta}3-values by rounding a potential core in the ({beta}2,{beta}3)- space. We examine the effect of the 'rounding' in the structure of the spectrum.

  8. Temperature dependence of an estuarine harmful algal bloom: Resolving interannual variability in bloom dynamics using a degree day approach.

    PubMed

    Ralston, David K; Keafer, Bruce A; Brosnahan, Michael L; Anderson, Donald M

    2014-01-01

    Observations of harmful algal blooms (HABs) of the dinoflagellate Alexandrium fundyense in an estuary over multiple years were used to assess drivers of their spatial and temporal variability. Nauset Estuary on Cape Cod, Massachusetts has a recurrent, self-seeding A. fundyense population that produces paralytic shellfish poisoning toxins and leads to nearly annual closure to shellfishing. Weekly surveys of the entire estuary were made in 3 of 4 consecutive years, with surveys of a subembayment during the intervening year. Major A. fundyense blooms were observed all 4 years, with maximum concentrations >10(6) cells L(-1). Concentrations were greatest in three salt ponds at the distal edges of the estuary. The bloom timing varied among the salt ponds and among years, although the blooms had similar durations and maximum cell concentrations. Nutrient concentrations did not correlate with the growth of the bloom, but differences in water temperature among years and ponds were significant. Net growth rates inferred from the surveys were similar to those from laboratory experiments, and increased linearly with temperature. A growing degree day calculation was used to account for effects of interannual variability and spatial gradients in water temperature on population development. The approach collapsed variability in the timing of bloom onset, development, and termination across years and among ponds, suggesting that this relatively simple metric could be used as an early-warning indicator for HABs in Nauset and similar areas with localized, self-seeding blooms.

  9. Alteration of Substrate Specificity: The Variable N-Terminal Domain of Tobacco Ca2+-Dependent Protein Kinase Is Important for Substrate Recognition[W

    PubMed Central

    Ito, Takeshi; Nakata, Masaru; Fukazawa, Jutarou; Ishida, Sarahmi; Takahashi, Yohsuke

    2010-01-01

    Protein kinases are major signaling molecules that are involved in a variety of cellular processes. However, the molecular mechanisms whereby protein kinases discriminate specific substrates are still largely unknown. Ca2+-dependent protein kinases (CDPKs) play central roles in Ca2+ signaling in plants. Previously, we found that a tobacco (Nicotiana tabacum) CDPK1 negatively regulated the transcription factor REPRESSION OF SHOOT GROWTH (RSG), which is involved in gibberellin feedback regulation. Here, we found that the variable N-terminal domain of CDPK1 is necessary for the recognition of RSG. A mutation (R10A) in the variable N-terminal domain of CDPK1 reduced both RSG binding and RSG phosphorylation while leaving kinase activity intact. Furthermore, the R10A mutation suppressed the in vivo function of CDPK1. The substitution of the variable N-terminal domain of an Arabidopsis thaliana CDPK, At CPK9, with that of Nt CDPK1 conferred RSG kinase activities. This chimeric CDPK behaved according to the identity of the variable N-terminal domain in transgenic plants. Our results open the possibility of engineering the substrate specificity of CDPK by manipulation of the variable N-terminal domain, enabling a rational rewiring of cellular signaling pathways. PMID:20442373

  10. Using variable-frequency asymmetries to probe the magnetic field dependence of radial transport in a Malmberg-Penning trap

    NASA Astrophysics Data System (ADS)

    Eggleston, D. L.

    2009-03-01

    A new experimental technique is used to study the dependence of asymmetry-induced radial particle flux Γ on axial magnetic field B in a modified Malmberg-Penning trap. This dependence is complicated by the fact that B enters the physics in at least two places: in the asymmetry-induced first order radial drift velocity vr = Eθ/B and in the zeroth order azimuthal drift velocity vθ = Er/B. To separate these, we employ the hypothesis that the latter always enters the physics in the combination ω-lωR, where ωR = vθ/r is the column rotation frequency and ω and l are the asymmetry frequency and azimuthal mode number, respectively. Points where ω-lωR = 0 are then selected from a Γ vs r vs ω data set, thus insuring that any function of this combination is constant. When the selected flux Γsel is plotted versus the density gradient, a roughly linear dependence is observed, showing that this selected flux is diffusive. This linear dependence is roughly independent of the bias of the center wire in our trap φcw. Since in our experiment ωR is proportional to φcw, this latter point shows that our technique has successfully removed any dependence on ωR and its derivatives, thus confirming our hypothesis. The slope of a least-squares fitted line through the Γsel vs density gradient data then gives the diffusion coefficient D0 under the condition ω-lωR = 0. Varying the magnetic field, we find D0 is proportional to B-1.33±0.05, a scaling that does not match any theory we know. These findings are then used to constrain the form of the empirical flux equation. It may be possible to extend this technique to give the functional dependence of the flux on ω-lωR.

  11. [Dependence of effects of weak combined low-frequency variable and constant magnetic fields on the intensity of asexual reproduction of planarians Dugesia tigrina on the magnitude of the variable field].

    PubMed

    Novikov, V V; Sheĭman, I M; Lisitsyn, A S; Kliubin, A V; Fesenko, E E

    2002-01-01

    It was shown that the stimulating effect of weak combined magnetic fields (constant component 42 microT, frequency of the variable component 3.7 Hz) on the division of planarians depends on the amplitude of the variable component of the field. The effect is particularly pronounced at 40 (the main maximum), 120, 160, and 640 nT. Narrow ranges of effective amplitudes alternate in some cases with equally narrow ranges in which the system does not respond to he treatment. In the range of super weak amplitudes of the variable field (0.1 and 1 nT), the stimulating effect is poorly pronounced. The data obtained indicate the presence of narrow amplitude windows in the response of the biological systems to weak and super weak magnetic fields. In a special series of experiments, it was shown that the effect of fields on planarians is partially mediated via aqueous medium preliminarily treated with weak magnetic fields. It is noteworthy that in experiments with water treated with weak magnetic fields, there were no pronounced maxima and minima in the magnitude of the effect in the range of amplitude of the variable magnetic field from 40 to 320 nT.

  12. The Association of Selected Conative Variables to Field-Dependence with Inferences for Reasoning Characteristics in Marketing Education.

    ERIC Educational Resources Information Center

    Fritz, Robert L.

    A study examined the association between field-dependence and its related information processing characteristics, and educational cognitive style as a model of conative influence. Data were collected from 145 secondary marketing education students in nothern Georgia during spring 1991. Descriptive statistics, Pearson product moment correlations,…

  13. How Disability and School-Related Variables Influence Social Security Dependence among Vulnerable Young People in Their Late Twenties

    ERIC Educational Resources Information Center

    Myklebust, Jon Olav

    2015-01-01

    The objective of this article is to investigate how psychosocial difficulties, functional level and school factors affect social security dependence among former students with special needs (N = 373). These individuals have been followed prospectively from their teens and into their late twenties. The study is theoretically inspired by life-course…

  14. Shifts in plant functional types have time-dependent and regionally variable impacts on dryland ecosystem water balance

    USGS Publications Warehouse

    Bradford, John B.; Schlaepfer, Daniel R.; Lauenroth, William K.; Burke, Ingrid C.

    2014-01-01

    5. Synthesis. This study provides a novel, regional-scale assessment of how plant functional type transitions may impact ecosystem water balance in sagebrush-dominated ecosystems of North America. Results illustrate that the ecohydrological consequences of changing vegetation depend strongly on climate and suggest that decreasing woody plant abundance may have only limited impact on evapotranspiration and water yield.

  15. A study on socio-medical variables of drug-dependent persons volunteering for treatment in Penang, Malaysia.

    PubMed

    Navaratnam, V; Spencer, C P

    1978-01-01

    There has been a rapid increase in the past five years in the numbers of hospitalized drug dependents. While the studied population was clearly unrepresentative of the country-wide drug using population, it illustrates how the problem is neither limited to one particular stratum of society, nor to the few "traditional" drugs. Indeed, an increasingly youthful group of individuals drawn from all backgrounds is not only becoming dependent upon opiates, but is also using a range of other drugs, all of which are available on the market at relatively low cost. The market prices of drugs have an effect on the pattern of drug use; and many individuals move directly from tobacco to heroin smoking. Drug abuse continues to be a considerable public and governmental concern, and enforcement and treatment programmes are rapidly expanding in attempts to resolve this problem. PMID:352461

  16. A study on socio-medical variables of drug-dependent persons volunteering for treatment in Penang, Malaysia.

    PubMed

    Navaratnam, V; Spencer, C P

    1978-01-01

    There has been a rapid increase in the past five years in the numbers of hospitalized drug dependents. While the studied population was clearly unrepresentative of the country-wide drug using population, it illustrates how the problem is neither limited to one particular stratum of society, nor to the few "traditional" drugs. Indeed, an increasingly youthful group of individuals drawn from all backgrounds is not only becoming dependent upon opiates, but is also using a range of other drugs, all of which are available on the market at relatively low cost. The market prices of drugs have an effect on the pattern of drug use; and many individuals move directly from tobacco to heroin smoking. Drug abuse continues to be a considerable public and governmental concern, and enforcement and treatment programmes are rapidly expanding in attempts to resolve this problem.

  17. PARAMETRIC AND NON PARAMETRIC (MARS: MULTIVARIATE ADDITIVE REGRESSION SPLINES) LOGISTIC REGRESSIONS FOR PREDICTION OF A DICHOTOMOUS RESPONSE VARIABLE WITH AN EXAMPLE FOR PRESENCE/ABSENCE OF AMPHIBIANS

    EPA Science Inventory

    The purpose of this report is to provide a reference manual that could be used by investigators for making informed use of logistic regression using two methods (standard logistic regression and MARS). The details for analyses of relationships between a dependent binary response ...

  18. Method-dependent variability in determination of prevalence of Campylobacter jejuni and Campylobacter coli in Canadian retail poultry.

    PubMed

    Carrillo, Catherine D; Plante, Daniel; Iugovaz, Irène; Kenwell, Robyn; Bélanger, Ghislaine; Boucher, Francine; Poulin, Nathalie; Trottier, Yvon-Louis

    2014-10-01

    Campylobacter is the most frequent cause of bacterial gastroenteritis in Canada, and the illness is commonly associated with poultry consumption. Whereas Canadian retail poultry is often contaminated with campylobacters, studies on the prevalence of this organism are inconsistent due to variability in sampling and microbiological methodology. To determine the current microbiological status of Canadian poultry, and to evaluate two commonly used microbiological methods, 348 raw poultry samples were collected at retail across Canada over a period of 3 years (2007 to 2010) and were analyzed for the presence of thermophilic Campylobacter species. The overall prevalence of Campylobacter spp. was found to be 42.8% by a combination of the two testing methods, with 33.9% of the samples positive for C. jejuni, 3.7% of the samples positive for C. coli, and 5.2% of the samples positive for both. Variability in Campylobacter spp. prevalence was observed in samples obtained from different regions across Canada and from poultry with or without skin, but this was not statistically significant. In co-contaminated samples, C. jejuni was preferentially recovered from Preston agar compared with mCCDA and Campy-Cefex agar, with an increase in recovery of C. coli on all selective media after 48 h of enrichment. A subset of 214 of the poultry rinses were analyzed by both Health Canada's standard method, MFLP-46 (enrichment in Park and Sanders broth), and a second method requiring enrichment in Bolton broth. Significantly more positive samples were obtained with the MFLP-46 method (40.6%) than with the alternate method (35.0%). This improved recovery with MFLP-46 may be due to the omission of cycloheximide from this method. These results demonstrate that determination of prevalence of Campylobacter spp. on poultry products may be significantly impacted by the choice of microbiological methods used. Canadian poultry continues to be a source of exposure to Campylobacter spp.

  19. Variable requirements for DNA-binding proteins at polycomb-dependent repressive regions in human HOX clusters.

    PubMed

    Woo, Caroline J; Kharchenko, Peter V; Daheron, Laurence; Park, Peter J; Kingston, Robert E

    2013-08-01

    Polycomb group (PcG)-mediated repression is an evolutionarily conserved process critical for cell fate determination and maintenance of gene expression during embryonic development. However, the mechanisms underlying PcG recruitment in mammals remain unclear since few regulatory sites have been identified. We report two novel prospective PcG-dependent regulatory elements within the human HOXB and HOXC clusters and compare their repressive activities to a previously identified element in the HOXD cluster. These regions recruited the PcG proteins BMI1 and SUZ12 to a reporter construct in mesenchymal stem cells and conferred repression that was dependent upon PcG expression. Furthermore, we examined the potential of two DNA-binding proteins, JARID2 and YY1, to regulate PcG activity at these three elements. JARID2 has differential requirements, whereas YY1 appears to be required for repressive activity at all 3 sites. We conclude that distinct elements of the mammalian HOX clusters can recruit components of the PcG complexes and confer repression, similar to what has been seen in Drosophila. These elements, however, have diverse requirements for binding factors, which, combined with previous data on other loci, speaks to the complexity of PcG targeting in mammals.

  20. Dependence of zero-bias resistance-area product and quantum efficiency on perimeter-to-area ratio in a variable-area diode array

    NASA Astrophysics Data System (ADS)

    Dhar, V.; Gopal, V.

    2001-07-01

    The dependence of the zero-bias resistance-area (RA) product and the quantum efficiency (η) of variable-area diode arrays is numerically calculated by solving the diffusion equation in a cylindrical, three-dimensional geometry in the thick base approximation. The calculation is done for long-wavelength IR HgCdTe n+-on-p diffusion-limited photodiodes at 77 K. The inverse resistance-area product 1/(RA) and the square root of the quantum efficiency, η1/2, are plotted against the perimeter-to-area (P/A) ratio. The 1/RA results are fitted to a quadratic dependence on the P/A ratio. The dependence of the 1/RA on the minority carrier diffusion length, the junction depth and the surface recombination velocity (SRV) is evaluated. An empirical expression is proposed that largely accounts for the dependence of the coefficients of the quadratic on these parameters and is more general than those used in previous studies. The results are also in reasonable agreement with the results of Briggs, expressed in terms of the parameter f3D, that are valid for zero junction depth and zero SRV. The slope of the quantum efficiency versus P/A plot, which is approximately a straight line, is related to an effective length Lopt, that also depends on the diffusion length, junction depth, SRV and the absorption coefficient α. The parameter Lopt varies as α1/2.

  1. Variable Transcriptional Regulation of the Human Aldosterone Synthase Gene Causes Salt-Dependent High Blood Pressure in Transgenic Mice

    PubMed Central

    Mopidevi, Brahmaraju; Kaw, Meenakshi K.; Puri, Nitin; Ponnala, Madhusudan; Jain, Sudhir; Rana, Anita; Keetha, Narsimha R.; Khuder, Sadik A.; Fiering, Steven N.; Kumar, Ashok

    2014-01-01

    Background Aldosterone, synthesized in the adrenal cortex by the enzyme CYP11B2, induces positive sodium balance and predisposes to hypertension. Various investigators, using genomic DNA analyses, have linked −344T polymorphism in the hCYP11B2 gene to human hypertension. Human CYP11B2 gene promoter has three SNPs in linkage disequilibrium: T/A at −663, T/C at −470 and C/T at −344. Variants ACT occur together and form the haplotype-I while variants TTC constitute haplotype-II. We hypothesize that these SNPs, when present together, will lead to haplotype-dependent differences in the transcriptional regulation of the hCYP11B2 gene and affect blood pressure regulation. Methods and Results We evaluated differences in tissue expression, in vivo, and consequential effects on blood pressure stemming from the two haplotypes. Novel transgenic (TG) mice with the hCYP11B2 gene, targeted to the mouse HPRT locus, with either haplotype-II or I variant are used in the study. Our results show increased adrenal and renal expression of hCYP11B2 in TG mice with haplotype-I, as compared to mice with haplotype-II. Importantly, we observed increased baseline blood pressure in haplotype-I TG mice, an effect accentuated by a high-salt diet. Pathophysiological impact of elevated aldosterone was corroborated by our results showing up-regulation of proinflammatory markers in renal tissues from the TG mice with haplotype-I. Conclusions These findings characterize haplotype-dependent regulation of the hCYP11B2 gene where −344T serves as a reporter polymorphism and show that haplotype-I leads to increased expression of hCYP11B2, with permissive effects on blood pressure and inflammatory milieu. PMID:25504670

  2. Caffeine Expectancy Questionnaire (CaffEQ): construction, psychometric properties, and associations with caffeine use, caffeine dependence, and other related variables.

    PubMed

    Huntley, Edward D; Juliano, Laura M

    2012-09-01

    Expectancies for drug effects predict drug initiation, use, cessation, and relapse, and may play a causal role in drug effects (i.e., placebo effects). Surprisingly little is known about expectancies for caffeine even though it is the most widely used psychoactive drug in the world. In a series of independent studies, the nature and scope of caffeine expectancies among caffeine consumers and nonconsumers were assessed, and a comprehensive and psychometrically sound Caffeine Expectancy Questionnaire (CaffEQ) was developed. After 2 preliminary studies, the CaffEQ was administered to 1,046 individuals from the general population along with other measures of interest (e.g., caffeine use history, anxiety). Exploratory factor analysis of the CaffEQ yielded a 7-factor solution. Subsequently, an independent sample of 665 individuals completed the CaffEQ and other measures, and a subset (n = 440) completed the CaffEQ again approximately 2 weeks later. Confirmatory factor analysis revealed good model fit, and test-retest reliability was very good. The frequency and quantity of caffeine use were associated with greater expectancies for withdrawal/dependence, energy/work enhancement, appetite suppression, social/mood enhancement, and physical performance enhancement and lower expectancies for anxiety/negative physical effects and sleep disturbance. Caffeine expectancies predicted various caffeine- associated features of substance dependence (e.g., use despite harm, withdrawal incidence and severity, perceived difficulty stopping use, tolerance). Expectancies for caffeine consumed via coffee were stronger than for caffeine consumed via soft drinks or tea. The CaffEQ should facilitate the advancement of our knowledge of caffeine and drug use in general. PMID:22149323

  3. Increased Variability and Asymmetric Expansion of the Hippocampal Spatial Representation in a Distal Cue-Dependent Memory Task.

    PubMed

    Park, Seong-Beom; Lee, Inah

    2016-08-01

    Place cells in the hippocampus fire at specific positions in space, and distal cues in the environment play critical roles in determining the spatial firing patterns of place cells. Many studies have shown that place fields are influenced by distal cues in foraging animals. However, it is largely unknown whether distal-cue-dependent changes in place fields appear in different ways in a memory task if distal cues bear direct significance to achieving goals. We investigated this possibility in this study. Rats were trained to choose different spatial positions in a radial arm in association with distal cue configurations formed by visual cue sets attached to movable curtains around the apparatus. The animals were initially trained to associate readily discernible distal cue configurations (0° vs. 80° angular separation between distal cue sets) with different food-well positions and then later experienced ambiguous cue configurations (14° and 66°) intermixed with the original cue configurations. Rats showed no difficulty in transferring the associated memory formed for the original cue configurations when similar cue configurations were presented. Place field positions remained at the same locations across different cue configurations, whereas stability and coherence of spatial firing patterns were significantly disrupted when ambiguous cue configurations were introduced. Furthermore, the spatial representation was extended backward and skewed more negatively at the population level when processing ambiguous cue configurations, compared with when processing the original cue configurations only. This effect was more salient for large cue-separation conditions than for small cue-separation conditions. No significant rate remapping was observed across distal cue configurations. These findings suggest that place cells in the hippocampus dynamically change their detailed firing characteristics in response to a modified cue environment and that some of the firing

  4. Environmentally co-occurring mercury resistance plasmids are genetically and phenotypically diverse and confer variable context-dependent fitness effects.

    PubMed

    Hall, James P J; Harrison, Ellie; Lilley, Andrew K; Paterson, Steve; Spiers, Andrew J; Brockhurst, Michael A

    2015-12-01

    Plasmids are important mobile elements that can facilitate genetic exchange and local adaptation within microbial communities. We compared the sequences of four co-occurring pQBR family environmental mercury resistance plasmids and measured their effects on competitive fitness of a Pseudomonas fluorescens SBW25 host, which was isolated at the same field site. Fitness effects of carriage differed between plasmids and were strongly context dependent, varying with medium, plasmid status of competitor and levels of environmental mercury. The plasmids also varied widely in their rates of conjugation and segregational loss. We found that few of the plasmid-borne accessory genes could be ascribed functions, although we identified a putative chemotaxis operon, a type IV pilus-encoding cluster and a region encoding putative arylsulfatase enzymes, which were conserved across geographically distant isolates. One plasmid, pQBR55, conferred the ability to catabolize sucrose. Transposons, including the mercury resistance Tn5042, appeared to have been acquired by different pQBR plasmids by recombination, indicating an important role for horizontal gene transfer in the recent evolution of pQBR plasmids. Our findings demonstrate extensive genetic and phenotypic diversity among co-occurring members of a plasmid community and suggest a role for environmental heterogeneity in the maintenance of plasmid diversity.

  5. A variable-order time-dependent neutron transport method for nuclear reactor kinetics using analytically-integrated space-time characteristics

    SciTech Connect

    Hoffman, A. J.; Lee, J. C.

    2013-07-01

    A new time-dependent neutron transport method based on the method of characteristics (MOC) has been developed. Whereas most spatial kinetics methods treat time dependence through temporal discretization, this new method treats time dependence by defining the characteristics to span space and time. In this implementation regions are defined in space-time where the thickness of the region in time fulfills an analogous role to the time step in discretized methods. The time dependence of the local source is approximated using a truncated Taylor series expansion with high order derivatives approximated using backward differences, permitting the solution of the resulting space-time characteristic equation. To avoid a drastic increase in computational expense and memory requirements due to solving many discrete characteristics in the space-time planes, the temporal variation of the boundary source is similarly approximated. This allows the characteristics in the space-time plane to be represented analytically rather than discretely, resulting in an algorithm comparable in implementation and expense to one that arises from conventional time integration techniques. Furthermore, by defining the boundary flux time derivative in terms of the preceding local source time derivative and boundary flux time derivative, the need to store angularly-dependent data is avoided without approximating the angular dependence of the angular flux time derivative. The accuracy of this method is assessed through implementation in the neutron transport code DeCART. The method is employed with variable-order local source representation to model a TWIGL transient. The results demonstrate that this method is accurate and more efficient than the discretized method. (authors)

  6. Buoyant Migration of Melt with Variable Physical Properties: Effect of Melt Viscosity and Its Dependence on Volatiles

    NASA Astrophysics Data System (ADS)

    Parmentier, E. M.

    2015-12-01

    Release of a volatile phase, usually considered to be water, from the downgoing plate and the upward migration of volatile saturated melt toward higher temperatures in the interior of the wedge is one mechanism for generation of melt at a convergent plate boundary (Gill, 1981; Grove et al. 2012). However, other volatiles, including CO2, may be released. Adding CO2 reduces the water mole fraction in melt that is stable at a given temperature. Dissolved water has a large effect on melt viscosity; but, CO2 has practically none, leading to the possibility of significant viscosity variations in melt rising through the mantle wedge. This may have important implications for the heterogeneity of erupted melts as discussed below."Saffman-Taylor" instability occurs as a low viscosity fluid flowing in porous media displaces another of higher viscosity. The low viscosity fluid forms fingers that extend progressively into the high viscosity fluid. For miscible fluids (no surface tension effects) in a non-compacting matrix (Chouke, 1982), the development of fingers is controlled by interdiffusion of the fluids.Numerical experiments to be reported examine viscous fingering in a compacting permeable matrix at conditions appropriate for melt generation in a mantle wedge. Mixing of melts with different CO2/water by diffusion in silicate melts alone is generally slow; however, fingering reduces the scale of CO2/water heterogeneity making diffusion more effective. We explore the persistence of a CO2/water heterogeneity of a given scale rising through the mantle wedge at a rate fast enough to preserve 230Th disequilibrium. The rise height over which heterogeneity can persist as fingers develop depends on the viscosity, i.e. CO2/water, variation initially present; viscosity variations on the order of 10% allow km-scale heterogeneity to persist over vertical scales comparable to the height of the wedge.

  7. Meteorological variables affect fertility rate after intrauterine artificial insemination in sheep in a seasonal-dependent manner: a 7-year study.

    PubMed

    Palacios, C; Abecia, J A

    2015-05-01

    A total number of 48,088 artificial inseminations (AIs) have been controlled during seven consecutive years in 79 dairy sheep Spanish farms (41° N). Mean, maximum and minimum ambient temperatures (Ts), temperature amplitude (TA), mean relative humidity (RH), mean solar radiation (SR) and total rainfall of each insemination day and 15 days later were recorded. Temperature-humidity index (THI) and effective temperature (ET) have been calculated. A binary logistic regression model to estimate the risk of not getting pregnant compared to getting pregnant, through the odds ratio (OR), was performed. Successful winter inseminations were carried out under higher SR (P < 0.01) and summer inseminations under lower SR values (P < 0.05). Successful inseminations during the summer were performed under significantly lower maximum T (P < 0.01), while winter inseminations resulted in pregnancy when they were carried out under higher maximum (P < 0.05) and minimum Ts (P < 0.01). Up to five meteorological variables presented OR >1 (maximum T, ET and rainfall on AI day, and ET and rainfall on day 15), and two variables presented OR <1 (SR on AI day and maximum T on day 15). However, the effect of meteorological factors affected fertility in opposite ways, so T becomes a protective or risk factor on fertility depending on season. In conclusion, the percentage of pregnancy after AI in sheep is significantly affected by meteorological variables in a seasonal-dependent manner, so the parameters such as temperature reverse their effects in the hot or cold seasons. A forecast of the meteorological conditions could be a useful tool when AI dates are being scheduled. PMID:25056126

  8. Meteorological variables affect fertility rate after intrauterine artificial insemination in sheep in a seasonal-dependent manner: a 7-year study

    NASA Astrophysics Data System (ADS)

    Palacios, C.; Abecia, J. A.

    2015-05-01

    A total number of 48,088 artificial inseminations (AIs) have been controlled during seven consecutive years in 79 dairy sheep Spanish farms (41° N). Mean, maximum and minimum ambient temperatures ( Ts), temperature amplitude (TA), mean relative humidity (RH), mean solar radiation (SR) and total rainfall of each insemination day and 15 days later were recorded. Temperature-humidity index (THI) and effective temperature (ET) have been calculated. A binary logistic regression model to estimate the risk of not getting pregnant compared to getting pregnant, through the odds ratio (OR), was performed. Successful winter inseminations were carried out under higher SR ( P < 0.01) and summer inseminations under lower SR values ( P < 0.05). Successful inseminations during the summer were performed under significantly lower maximum T ( P < 0.01), while winter inseminations resulted in pregnancy when they were carried out under higher maximum ( P < 0.05) and minimum Ts ( P < 0.01). Up to five meteorological variables presented OR >1 (maximum T, ET and rainfall on AI day, and ET and rainfall on day 15), and two variables presented OR <1 (SR on AI day and maximum T on day 15). However, the effect of meteorological factors affected fertility in opposite ways, so T becomes a protective or risk factor on fertility depending on season. In conclusion, the percentage of pregnancy after AI in sheep is significantly affected by meteorological variables in a seasonal-dependent manner, so the parameters such as temperature reverse their effects in the hot or cold seasons. A forecast of the meteorological conditions could be a useful tool when AI dates are being scheduled.

  9. Breeder and batch-dependent variability in the acquisition and performance of a motor skill in adult Long-Evans rats.

    PubMed

    O'Bryant, Amber J; Allred, Rachel P; Maldonado, Monica A; Cormack, Lawrence K; Jones, Theresa A

    2011-10-10

    Reaching tasks are popular tools for investigating the neural mechanisms of motor skill learning and recovery from brain damage in rodents, but there is considerable unexplained variability across studies using these tasks. We investigated whether breeder, batch effects, experimenter, time of year, weight and other factors contribute to differences in the acquisition and performance of a skilled reaching task, the single pellet retrieval task, in adult male Long-Evans hooded rats. First, we retrospectively analyzed task acquisition and performance in rats from different breeding colonies that were used in several studies spanning a 3 year period in our laboratory. Second, we compared reaching variables in age-matched rats from different breeders that were trained together as a batch by the same experimenters. All rats had received daily training on the reaching task until they reached a criterion of successful reaches per attempt. We found significant breeder-dependent differences in learning rate and final performance level. This was found even when age-matched rats from different breeders were trained together by the same experimenters. There was also significant batch-to-batch variability within rats from the same breeder trained by the same experimenter. Other factors, including weight, paw preference and the experimenter, were not as strong or consistent in their contributions to differences across studies. The breeder and batch effects found within the same rat strain may reflect genetic and environmental influences on the neural substrates of motor skill learning. This is an important consideration when comparing baseline performance across studies and for controlling variability within studies.

  10. Novel analogues of chlormethiazole are neuroprotective in four cellular models of neurodegeneration by a mechanism with variable dependence on GABAA receptor potentiation

    PubMed Central

    VandeVrede, Lawren; Tavassoli, Ehsan; Luo, Jia; Qin, Zhihui; Yue, Lan; Pepperberg, David R; Thatcher, Gregory R

    2014-01-01

    Background and Purpose: Chlormethiazole (CMZ), a clinical sedative/anxiolytic agent, did not reach clinical efficacy in stroke trials despite neuroprotection demonstrated in numerous animal models. Using CMZ as a lead compound, neuroprotective methiazole (MZ) analogues were developed, and neuroprotection and GABAA receptor dependence were studied. Experimental Approach: Eight MZs were selected from a novel library, of which two were studied in detail. Neuroprotection, glutamate release, intracellular calcium and response to GABA blockade by picrotoxin were measured in rat primary cortical cultures using four cellular models of neurodegeneration. GABA potentiation was assayed in oocytes expressing the α1β2γ2 GABAA receptor. Key Results: Neuroprotection against a range of insults was retained even with substantial chemical modification. Dependence on GABAA receptor activity was variable: at the extremes, neuroprotection by GN-28 was universally sensitive to picrotoxin, while GN-38 was largely insensitive. In parallel, effects on extracellular glutamate and intracellular calcium were associated with GABAA dependence. Consistent with these findings, GN-28 potentiated α1β2γ2 GABAA function, whereas GN-38 had a weak inhibitory effect. Neuroprotection against moderate dose oligomeric Aβ1–42 was also tolerant to structural changes. Conclusions and Implications: The results support the concept that CMZ does not contain a single pharmacophore, rather that broad-spectrum neuroprotection results from a GABAA-dependent mechanism represented by GN-28, combined with a mechanism represented in GN-38 that shows the least dependence on GABAA receptors. These findings allow further refinement of the neuroprotective pharmacophore and investigation into secondary mechanisms that will assist in identifying MZ-based compounds of use in treating neurodegeneration. PMID:24116891

  11. An alternative approach to exact wave functions for time-dependent coupled oscillator model of charged particle in variable magnetic field

    SciTech Connect

    Menouar, Salah; Maamache, Mustapha; Choi, Jeong Ryeol

    2010-08-15

    The quantum states of time-dependent coupled oscillator model for charged particles subjected to variable magnetic field are investigated using the invariant operator methods. To do this, we have taken advantage of an alternative method, so-called unitary transformation approach, available in the framework of quantum mechanics, as well as a generalized canonical transformation method in the classical regime. The transformed quantum Hamiltonian is obtained using suitable unitary operators and is represented in terms of two independent harmonic oscillators which have the same frequencies as that of the classically transformed one. Starting from the wave functions in the transformed system, we have derived the full wave functions in the original system with the help of the unitary operators. One can easily take a complete description of how the charged particle behaves under the given Hamiltonian by taking advantage of these analytical wave functions.

  12. Origins of intersubject variability of blood oxygenation level dependent and arterial spin labeling fMRI: implications for quantification of brain activity.

    PubMed

    Gaxiola-Valdez, Ismael; Goodyear, Bradley G

    2012-12-01

    Accurate localization of brain activity using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been challenged because of the large BOLD signal within distal veins. Arterial spin labeling (ASL) techniques offer greater sensitivity to the microvasculature but possess low temporal resolution and limited brain coverage. In this study, we show that the physiological origins of BOLD and ASL depend on whether percent change or statistical significance is being considered. For BOLD and ASL fMRI data collected during a simple unilateral hand movement task, we found that in the area of the contralateral motor cortex the centre of gravity (CoG) of the intersubject coefficient of variation (CV) of BOLD fMRI was near the brain surface for percent change in signal, whereas the CoG of the intersubject CV for Z-score was in close proximity of sites of brain activity for both BOLD and ASL. These findings suggest that intersubject variability of BOLD percent change is vascular in origin, whereas the origin of inter-subject variability of Z-score is neuronal for both BOLD and ASL. For longer duration tasks (12 s or greater), however, there was a significant correlation between BOLD and ASL percent change, which was not evident for short duration tasks (6 s). These findings suggest that analyses directly comparing percent change in BOLD signal between pre-defined regions of interest using short duration stimuli, as for example in event-related designs, may be heavily weighted by large-vessel responses rather than neuronal responses.

  13. Improvement of NADPH bioavailability in Escherichia coli by replacing NAD(+)-dependent glyceraldehyde-3-phosphate dehydrogenase GapA with NADP (+)-dependent GapB from Bacillus subtilis and addition of NAD kinase.

    PubMed

    Wang, Yipeng; San, Ka-Yiu; Bennett, George N

    2013-12-01

    Enzymatic synthesis of some industrially important compounds depends heavily on cofactor NADPH as the reducing agent. This is especially true in the synthesis of chiral compounds that are often used as pharmaceutical intermediates to generate the correct stereochemistry in bioactive products. The high cost and technical difficulty of cofactor regeneration often pose a challenge for such biocatalytic reactions. In this study, to increase NADPH bioavailability, the native NAD(+)-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gapA gene in Escherichia coli was replaced with a NADP(+)-dependent gapB from Bacillus subtilis. To overcome the limitation of NADP(+) availability, E. coli NAD kinase, nadK was also coexpressed with gapB. The recombinant strains were then tested in three reporting systems: biosynthesis of lycopene, oxidation of cyclohexanone with cyclohexanone monooxygenase (CHMO), and an anaerobic system utilizing 2-haloacrylate reductase (CAA43). In all the reporting systems, replacing NAD(+)-dependent GapA activity with NADP(+)-dependent GapB activity increased the synthesis of NADPH-dependent compounds. The increase was more pronounced when NAD kinase was also overexpressed in the case of the one-step reaction catalyzed by CAA43 which approximately doubled the product yield. These results validate this novel approach to improve NADPH bioavailability in E. coli and suggest that the strategy can be applied in E. coli or other bacterium-based production of NADPH-dependent compounds.

  14. A new method to detect transitory signatures and local time/space variability structures in the climate system: the scale-dependent correlation analysis

    NASA Astrophysics Data System (ADS)

    Rodó, Xavier; Rodríguez-Arias, Miquel-Àngel

    2006-10-01

    The study of transitory signals and local variability structures in both/either time and space and their role as sources of climatic memory, is an important but often neglected topic in climate research despite its obvious importance and extensive coverage in the literature. Transitory signals arise either from non-linearities, in the climate system, transitory atmosphere-ocean couplings, and other processes in the climate system evolving after a critical threshold is crossed. These temporary interactions that, though intense, may not last long, can be responsible for a large amount of unexplained variability but are normally considered of limited relevance and often, discarded. With most of the current techniques at hand these typology of signatures are difficult to isolate because the low signal-to-noise ratio in midlatitudes, the limited recurrence of the transitory signals during a customary interval of data considered. Also, there is often a serious problem arising from the smoothing of local or transitory processes if statistical techniques are applied, that consider all the length of data available, rather than taking into account the size of the specific variability structure under investigation. Scale-dependent correlation (SDC) analysis is a new statistical method capable of highlighting the presence of transitory processes, these former being understood as temporary significant lag-dependent autocovariance in a single series, or covariance structures between two series. This approach, therefore, complements other approaches such as those resulting from the families of wavelet analysis, singular-spectrum analysis and recurrence plots. A main feature of SDC is its high-performance for short time series, its ability to characterize phase-relationships and thresholds in the bivariate domain. Ultimately, SDC helps tracking short-lagged relationships among processes that locally or temporarily couple and uncouple. The use of SDC is illustrated in the present

  15. Cell Line-Dependent Variability of Coordinate Expression of p75NTR and CRABP1 and Modulation of Effects of Fenretinide on Neuroblastoma Cells

    PubMed Central

    Yang, Yaoli Pu; Wang, Simeng; Li, Xingguo; Schor, Nina F.

    2016-01-01

    Neuroblastoma is a childhood neural crest tumor. Fenretinide, a retinoic acid analogue, induces accumulation of mitochondrial reactive oxygen species and consequent apoptosis in neuroblastoma cells. The p75 neurotrophin receptor (p75NTR) enhances the antineuroblastoma cell efficacy of fenretinide in vitro. We examined the role of the retinoid binding protein, CRABP1, in p75NTR-mediated potentiation of the efficacy of fenretinide. Knockdown and overexpression, respectively, of either p75NTR or CRABP1 were effected in neuroblastoma cell lines using standard techniques. Expression was determined by qRT-PCR and confirmed at the protein level by Western blot. Metabolic viability was determined by Alamar blue assay. While protein content of CRABP1 correlated roughly with that of p75NTR in the three neuroblastoid or epithelioid human neuroblastoma cell lines studied, manipulation of p75NTR expression resulted in cell line-dependent, variable change in CRABP1 expression. Furthermore, in some cell lines, induced expression of CRABP1 in the absence of p75NTR did not alter cell sensitivity to fenretinide treatment. The effects of manipulation of p75NTR expression on CRABP1 expression and the effects of CRABP1 expression on fenretinide efficacy are therefore neuroblastoma cell line-dependent. Potentiation of the antineuroblastoma cell effects of fenretinide by p75NTR is not mediated solely through CRABP1. PMID:26843908

  16. Vaccine induced antibodies to the first variable loop of human immunodeficiency virus type 1 gp120, mediate antibody-dependent virus inhibition in macaques.

    PubMed

    Bialuk, Izabela; Whitney, Stephen; Andresen, Vibeke; Florese, Ruth H; Nacsa, Janos; Cecchinato, Valentina; Valeri, Valerio W; Heraud, Jean-Michel; Gordon, Shari; Parks, Robyn Washington; Montefiori, David C; Venzon, David; Demberg, Thorsten; Guroff, Marjorie Robert-; Landucci, Gary; Forthal, Donald N; Franchini, Genoveffa

    2011-12-01

    The role of antibodies directed against the hyper variable envelope region V1 of human immunodeficiency virus type 1 (HIV-1), has not been thoroughly studied. We show that a vaccine able to elicit strain-specific non-neutralizing antibodies to this region of gp120 is associated with control of highly pathogenic chimeric SHIV(89.6P) replication in rhesus macaques. The vaccinated animal that had the highest titers of antibodies to the amino terminus portion of V1, prior to challenge, had secondary antibody responses that mediated cell killing by antibody-dependent cellular cytotoxicity (ADCC), as early as 2 weeks after infection and inhibited viral replication by antibody-dependent cell-mediated virus inhibition (ADCVI), by 4 weeks after infection. There was a significant inverse correlation between virus level and binding antibody titers to the envelope protein, (R=-0.83, p=0.015), and ADCVI (R=-0.84 p=0.044). Genotyping of plasma virus demonstrated in vivo selection of three SHIV(89.6P) variants with changes in potential N-linked glycosylation sites in V1. We found a significant inverse correlation between virus levels and titers of antibodies that mediated ADCVI against all the identified V1 virus variants. A significant inverse correlation was also found between neutralizing antibody titers to SHIV(89.6) and virus levels (R=-0.72 p=0.0050). However, passive inoculation of purified immunoglobulin from animal M316, the macaque that best controlled virus, to a naïve macaque, resulted in a low serum neutralizing antibodies and low ADCVI activity that failed to protect from SHIV(89.6P) challenge. Collectively, while our data suggest that anti-envelope antibodies with neutralizing and non-neutralizing Fc(R-dependent activities may be important in the control of SHIV replication, they also demonstrate that low levels of these antibodies alone are not sufficient to protect from infection.

  17. Evidence for protein kinase C-dependent and -independent activation of mitogen-activated protein kinase in T cells: potential role of additional diacylglycerol binding proteins.

    PubMed

    Puente, L G; Stone, J C; Ostergaard, H L

    2000-12-15

    Activation of mitogen-activated protein kinases (MAPK) is a critical signal transduction event for CTL activation, but the signaling mechanisms responsible are not fully characterized. Protein kinase C (PKC) is thought to contribute to MAPK activation following TCR stimulation. We have found that dependence on PKC varies with the method used to stimulate the T cells. Extracellular signal-regulated kinase (ERK) activation in CTL stimulated with soluble cross-linked anti-CD3 is completely inhibited by the PKC inhibitor bisindolylmaleimide (BIM). In contrast, only the later time points in the course of ERK activation are sensitive to BIM when CTL are stimulated with immobilized anti-CD3, a condition that stimulates CTL degranulation. Surprisingly, MAPK activation in response to immobilized anti-CD3 is strongly inhibited at all time points by the diacylglycerol (DAG)-binding domain inhibitor calphostin C implicating the contribution of a DAG-dependent but PKC-independent pathway in the activation of ERK in CTL clones. Chronic exposure to phorbol ester down-regulates the expression of DAG-responsive PKC isoforms; however, this treatment of CTL clones does not inhibit anti-CD3-induced activation of MAPK. Phorbol ester-treated cells have reduced expression of several isoforms of PKC but still express the recently described DAG-binding Ras guanylnucleotide-releasing protein. These results indicate that the late phase of MAPK activation in CTL clones in response to immobilized anti-CD3 stimulation requires PKC while the early phase requires a DAG-dependent, BIM-resistant component.

  18. Food additives

    PubMed Central

    Spencer, Michael

    1974-01-01

    Food additives are discussed from the food technology point of view. The reasons for their use are summarized: (1) to protect food from chemical and microbiological attack; (2) to even out seasonal supplies; (3) to improve their eating quality; (4) to improve their nutritional value. The various types of food additives are considered, e.g. colours, flavours, emulsifiers, bread and flour additives, preservatives, and nutritional additives. The paper concludes with consideration of those circumstances in which the use of additives is (a) justified and (b) unjustified. PMID:4467857

  19. Bioaugmentation of nitrate-dependent anaerobic ferrous oxidation by heterotrophic denitrifying sludge addition: A promising way for promotion of chemoautotrophic denitrification.

    PubMed

    Wang, Ru; Zheng, Ping; Zhang, Meng; Zhao, He-Ping; Ji, Jun-Yuan; Zhou, Xiao-Xin; Li, Wei

    2015-12-01

    Nitrate-dependent anaerobic ferrous oxidation (NAFO) is a new and valuable bio-process for the treatment of wastewaters with low C/N ratio, and the NAFO process is in state of the art. The heterotrophic denitrifying sludge (HDS), possessing NAFO activity, was used as bioaugmentation to enhance NAFO efficiency. At a dosage of 6% (V/V), the removal of nitrate and ferrous was 2.4 times and 2.3 times of as primary, and the volumetric removal rate (VRR) of nitrate and ferrous was 2.4 times and 2.2 times of as primary. Tracing experiments of HDS indicated that the bioaugmentation on NAFO reactor was resulted from the NAFO activity by HDS itself. The predominant bacteria in HDS were identified as Thauera (52.5%) and Hyphomicrobium (20.0%) which were typical denitrifying bacteria and had potential ability to oxidize ferrous. In conclusion, HDS could serve as bioaugmentation or a new seeding sludge for operating high-efficiency NAFO reactors. PMID:26348287

  20. Addition of thymidine to culture media for accurate examination of thymidine-dependent small-colony variants of methicillin-resistant Staphylococcus aureus: a pilot study.

    PubMed

    Horiuchi, Kazuki; Matsumoto, Takehisa; Ota, Yusuke; Kasuga, Eriko; Negishi, Tatsuya; Yaguchi, Tomomi; Sugano, Mitsutoshi; Honda, Takayuki

    2015-03-01

    Small-colony variants (SCVs) are slow-growing subpopulations of various auxotrophic bacterial strains. Thymidine-dependent SCVs (TD-SCVs) are unable to synthesize thymidine; hence, these variants fail to grow in a medium without thymidine. In this study, we used 10 TD-SCVs of Staphylococcus aureus, of which four strains possessed mecA. We compared the efficacy of a newly modified medium containing thymidine for the detection of TD-SCVs of methicillin-resistant S. aureus (MRSA) to the efficacy of routinely used laboratory media. We observed that none of the 10 TD-SCVs of S. aureus grew in Mueller-Hinton agar, and four TD-SCVs of MRSA failed to grow on all MRSA screening media, except for the ChromID™ MRSA medium. Laboratory tests conducted using medium with thymidine incorporated showed that thymidine did not affect the minimum inhibitory concentrations of oxacillin and cefoxitin for clinical isolates of S. aureus, and was able to detect MRSA, including TD-SCVs. These findings showed that thymidine-incorporated media are able to detect TD-SCVs of MRSA without altering the properties of other clinically isolated MRSA strains.

  1. Surface vapor conductance derived from the ETRHEQ: Dependence on environmental variables and similarity to Oren's stomatal stress model for vapor pressure deficit

    NASA Astrophysics Data System (ADS)

    Salvucci, G.; Rigden, A. J.

    2015-12-01

    Daily time series of evapotranspiration and surface conductance to water vapor were estimated using the ETRHEQ method (Evapotranspiration from Relative Humidity at Equilibrium). ETRHEQ has been previously compared with ameriflux site-level measurements of ET at daily and seasonal time scales, with watershed water balance estimates, and with various benchmark ET data sets. The ETRHEQ method uses meteorological data collected at common weather stations and estimates the surface conductance by minimizing the vertical variance of the calculated relative humidity profile averaged over the day. The key advantage of the ETRHEQ method is that it does not require knowledge of the surface state (soil moisture, stomatal conductance, leaf are index, etc.) or site-specific calibration. The daily estimates of conductance from 229 weather stations for 53 years were analyzed for dependence on environmental variables known to impact stomatal conductance and soil diffusivity: surface temperature, surface vapor pressure deficit, solar radiation, antecedent precipitation (as a surrogate for soil moisture), and a seasonal vegetation greenness index. At each site the summertime (JJAS) conductance values estimated from ETRHEQ were fitted to a multiplicate Jarvis-type stress model. Functional dependence was not proscribed, but instead fitted using flexible piecewise-linear splines. The resulting stress functions reproduce the time series of conductance across a wide range of ecosystems and climates. The VPD stress term resembles that proposed by Oren (i.e., 1-m*log(VPD) ), with VPD measured in kilopascals. The equivalent value of m derived from our spline-fits at each station varied over a remarkably small range of 0.58 to 0.62, in agreement with Oren's original analysis based on leaf and tree-level measurements.

  2. Variability in State-Dependent Plasticity of Intrinsic Properties during Cell-Autonomous Self-Regulation of Calcium Homeostasis in Hippocampal Model Neurons1,2,3

    PubMed Central

    Srikanth, Sunandha

    2015-01-01

    Abstract How do neurons reconcile the maintenance of calcium homeostasis with perpetual switches in patterns of afferent activity? Here, we assessed state-dependent evolution of calcium homeostasis in a population of hippocampal pyramidal neuron models, through an adaptation of a recent study on stomatogastric ganglion neurons. Calcium homeostasis was set to emerge through cell-autonomous updates to 12 ionic conductances, responding to different types of synaptically driven afferent activity. We first assessed the impact of theta-frequency inputs on the evolution of ionic conductances toward maintenance of calcium homeostasis. Although calcium homeostasis emerged efficaciously across all models in the population, disparate changes in ionic conductances that mediated this emergence resulted in variable plasticity to several intrinsic properties, also manifesting as significant differences in firing responses across models. Assessing the sensitivity of this form of plasticity, we noted that intrinsic neuronal properties and the firing response were sensitive to the target calcium concentration and to the strength and frequency of afferent activity. Next, we studied the evolution of calcium homeostasis when afferent activity was switched, in different temporal sequences, between two behaviorally distinct types of activity: theta-frequency inputs and sharp-wave ripples riding on largely silent periods. We found that the conductance values, intrinsic properties, and firing response of neurons exhibited differential robustness to an intervening switch in the type of afferent activity. These results unveil critical dissociations between different forms of homeostasis, and call for a systematic evaluation of the impact of state-dependent switches in afferent activity on neuronal intrinsic properties during neural coding and homeostasis. PMID:26464994

  3. Effectiveness of the Touch Math Technique in Teaching Basic Addition to Children with Autism

    ERIC Educational Resources Information Center

    Yikmis, Ahmet

    2016-01-01

    This study aims to reveal whether the touch math technique is effective in teaching basic addition to children with autism. The dependent variable of this study is the children's skills to solve addition problems correctly, whereas teaching with the touch math technique is the independent variable. Among the single-subject research models, a…

  4. Fracture mode, microstructure and temperature-dependent elastic moduli for thermoelectric composites of PbTe PbS with SiC nanoparticle additions

    SciTech Connect

    Ni, Jennifer E; Case, Eldon D; Hogan, Timophy P.; Trejo, Rosa M; Lara-Curzio, Edgar; Kanatzidis, Mercouri G.

    2013-01-01

    Twenty-six (Pb0.95Sn0.05Te)0.92(PbS)0.08 0.055% PbI2 SiC nanoparticle (SiCnp) composite thermoelectric specimens were either hot pressed or pulsed electric current sintered (PECS). Bloating (a thermally induced increase in porosity, P, for as-densified specimens) was observed during annealing at temperatures >603 K for hot-pressed specimens and PECS-processed specimens from wet milled powders, but in contrast seven out of seven specimens densified by PECS from dry milled powders showed no observable bloating following annealing at temperatures up to 936 K. In this study, bloating in the specimens was accessed via thermal annealing induced changes in (i) porosity measured by scanning electron microscopy on fractured specimen surfaces, (ii) specimen volume and (iii) elastic moduli. The moduli were measured by resonant ultrasound spectroscopy. SiCnp additions (1 3.5 vol.%) changed the fracture mode from intergranular to transgranular, inhibited grain growth, and limited bloating in the wet milled PECS specimens. Inhibition of bloating likely occurs due to cleaning of contamination from powder particle surfaces via PECS processing which has been reported previously in the literature.

  5. Pressure-dependent competition among reaction pathways from first- and second-O2 additions in the low-temperature oxidation of tetrahydrofuran

    DOE PAGES

    Antonov, Ivan O.; Zador, Judit; Rotavera, Brandon; Papajak, Ewa; Osborn, David L.; Taatjes, Craig A.; Sheps, Leonid

    2016-07-21

    Here, we report a combined experimental and quantum chemistry study of the initial reactions in low-temperature oxidation of tetrahydrofuran (THF). Using synchrotron-based time-resolved VUV photoionization mass spectrometry, we probe numerous transient intermediates and products at P = 10–2000 Torr and T = 400–700 K. A key reaction sequence, revealed by our experiments, is the conversion of THF-yl peroxy to hydroperoxy-THF-yl radicals (QOOH), followed by a second O2 addition and subsequent decomposition to dihydrofuranyl hydroperoxide + HO2 or to γ-butyrolactone hydroperoxide + OH. The competition between these two pathways affects the degree of radical chain-branching and is likely of central importancemore » in modeling the autoignition of THF. We interpret our data with the aid of quantum chemical calculations of the THF-yl + O2 and QOOH + O2 potential energy surfaces. On the basis of our results, we propose a simplified THF oxidation mechanism below 700 K, which involves the competition among unimolecular decomposition and oxidation pathways of QOOH.« less

  6. Pressure-Dependent Competition among Reaction Pathways from First- and Second-O2 Additions in the Low-Temperature Oxidation of Tetrahydrofuran.

    PubMed

    Antonov, Ivan O; Zádor, Judit; Rotavera, Brandon; Papajak, Ewa; Osborn, David L; Taatjes, Craig A; Sheps, Leonid

    2016-08-25

    We report a combined experimental and quantum chemistry study of the initial reactions in low-temperature oxidation of tetrahydrofuran (THF). Using synchrotron-based time-resolved VUV photoionization mass spectrometry, we probe numerous transient intermediates and products at P = 10-2000 Torr and T = 400-700 K. A key reaction sequence, revealed by our experiments, is the conversion of THF-yl peroxy to hydroperoxy-THF-yl radicals (QOOH), followed by a second O2 addition and subsequent decomposition to dihydrofuranyl hydroperoxide + HO2 or to γ-butyrolactone hydroperoxide + OH. The competition between these two pathways affects the degree of radical chain-branching and is likely of central importance in modeling the autoignition of THF. We interpret our data with the aid of quantum chemical calculations of the THF-yl + O2 and QOOH + O2 potential energy surfaces. On the basis of our results, we propose a simplified THF oxidation mechanism below 700 K, which involves the competition among unimolecular decomposition and oxidation pathways of QOOH. PMID:27441526

  7. Single-chain Variable Fragment Albumin Fusions Bind the Neonatal Fc Receptor (FcRn) in a Species-dependent Manner

    PubMed Central

    Andersen, Jan Terje; Cameron, Jason; Plumridge, Andrew; Evans, Leslie; Sleep, Darrell; Sandlie, Inger

    2013-01-01

    Albumin has a serum half-life of 3 weeks in humans. This has been utilized to extend the serum persistence of biopharmaceuticals that are fused to albumin. In light of the fact that the neonatal Fc receptor (FcRn) is a key regulator of albumin homeostasis, it is crucial to address how fusion of therapeutics to albumin impacts binding to FcRn. Here, we report on a detailed molecular investigation on how genetic fusion of a short peptide or an single-chain variable fragment (scFv) fragment to human serum albumin (HSA) influences pH-dependent binding to FcRn from mouse, rat, monkey, and human. We have found that fusion to the N- or C-terminal end of HSA only slightly reduces receptor binding, where the most noticeable effect is seen after fusion to the C-terminal end. Furthermore, in contrast to the observed strong binding to human and monkey FcRn, HSA and all HSA fusions bound very poorly to mouse and rat versions of the receptor. Thus, we demonstrate that conventional rodents are limited as preclinical models for analysis of serum half-life of HSA-based biopharmaceuticals. This finding is explained by cross-species differences mainly found within domain III (DIII) of albumin. Our data demonstrate that although fusion, particularly to the C-terminal end, may slightly reduce the affinity for FcRn, HSA is versatile as a carrier of biopharmaceuticals. PMID:23818524

  8. Characterization of neutralizing monoclonal antibodies to linear and conformation-dependent epitopes within the first and second variable domains of human immunodeficiency virus type 1 gp120.

    PubMed Central

    McKeating, J A; Shotton, C; Cordell, J; Graham, S; Balfe, P; Sullivan, N; Charles, M; Page, M; Bolmstedt, A; Olofsson, S

    1993-01-01

    A number of linear and conformation-dependent neutralizing monoclonal antibodies (MAbs) have been mapped to the first and second variable (V1 and V2) domains of human immunodeficiency virus type 1 (HIV-1) gp120. The majority of these MAbs are as effective at neutralizing HIV-1 infectivity as MAbs to the V3 domain and the CD4 binding site. The linear MAbs bind to amino acid residues 162 to 171, and changes at residues 183/184 (PI/SG) and 191/192/193 (YSL/GSS) within the V2 domain abrogate the binding of the two conformation-dependent MAbs, 11/68b and CRA-4, respectively. Surprisingly, a change at residue 435 (Y/H or Y/S), in a region of gp120 near the CD4 binding site (M. Kowalski, J. Potz, L. Basiripour, T. Dorfman, W. C. Goh, E. Terwilliger, A. Dayton, C. Rosen, W. Haseltine, and J. Sodroski, Science 237:1351-1355, 1987; L. A. Lasky, G. M. Nakamura, D. H. Smith, C. Fennie, C. Shimasaki, E. Patzer, P. Berman, T. Gregory, and D. Capon, Cell 50:975-985, 1987; and U. Olshevsky, E. Helseth, C. Furman, J. Li, W. Haseltine, and J. Sodroski, J. Virol. 64:5701-5707, 1990), abrogated gp120 recognition by both of the conformation-dependent MAbs. However, both MAbs 11/68b and CRA-4 were able to bind to HIV-1 V1V2 chimeric fusion proteins expressing the V1V2 domains in the absence of C4, suggesting that residues in C4 are not components of the epitopes but that amino acid changes in C4 may affect the structure of the V1V2 domains. This is consistent with the ability of soluble CD4 to block 11/68b and CRA-4 binding to both native cell surface-expressed gp120 and recombinant gp120 and suggests that the binding of the neutralizing MAbs to the virus occurs prior to receptor interaction. Since the reciprocal inhibition, i.e., antibody inhibition of CD4-gp120 binding, was not observed, the mechanism of neutralization is probably not a blockade of virus-receptor interaction. Finally, we demonstrate that linear sequences from the V2 region are immunogenic in HIV-1-infected individuals

  9. Neuronal morphology in MeCP2 mouse models is intrinsically variable and depends on age, cell type, and Mecp2 mutation.

    PubMed

    Wang, I-Ting J; Reyes, Arith-Ruth S; Zhou, Zhaolan

    2013-10-01

    Rett Syndrome (RTT), a progressive neurological disorder characterized by developmental regression and loss of motor and language skills, is caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MECP2). Neurostructural phenotypes including decreased neuronal size, dendritic complexity, and spine density have been reported in postmortem RTT brain tissue and in Mecp2 animal models. How these changes in neuronal morphology are related to RTT-like phenotype and MeCP2 function, and the extent to which restoration of neuronal morphology can be used as a cellular readout in therapeutic studies, however, remain unclear. Here, we systematically examined neuronal morphology in vivo across three Mecp2 mouse models representing Mecp2 loss-of-function, partial loss-of-function, and gain-of-function mutations, at developmental time points corresponding to early- and late-symptomatic RTT-like behavioral phenotypes. We found that in Mecp2 loss-of-function mouse models, dendritic complexity is reduced in a mild, age-dependent, and brain region-specific manner, whereas soma size is reduced consistently throughout development. Neither phenotype, however, is altered in Mecp2 gain-of-function mice. Our results suggest that, in the cell types we examined, the use of dendritic morphology as a cellular readout of RTT phenotype and therapeutic efficacy should be cautioned, as it is intrinsically variable. In contrast, soma size may be a robust and reliable marker for evaluation of MeCP2 function in Mecp2 loss-of-function studies.

  10. Germline PRKACA amplification causes variable phenotypes that may depend on the extent of the genomic defect: molecular mechanisms and clinical presentations

    PubMed Central

    Lodish, Maya B.; Yuan, Bo; Levy, Isaac; Braunstein, Glenn D.; Lyssikatos, Charalampos; Salpea, Paraskevi; Szarek, Eva; Karageorgiadis, Alexander S.; Belyavskaya, Elena; Raygada, Margarita; Faucz, Fabio Rueda; Izatt, Louise; Brain, Caroline; Gardner, James; Quezado, Martha; Carney, J. Aidan; Lupski, James R.; Stratakis, Constantine A.

    2015-01-01

    Objective We reported recently 5 patients with bilateral adrenocortical hyperplasia (BAH) and Cushing syndrome (CS) caused by constitutive activation of the catalytic subunit of protein kinase A (PRKACA). By doing new, in depth analysis of their cytogenetic abnormality, we attempt a better genotype-phenotype correlation of their PRKACA amplification. Design Case series. Methods Molecular cytogenetic, genomic, clinical and histopathologic analyses were performed in 5 patients with CS. Results Reinvestigation of the defects of previously described patients by state-of-the-art molecular cytogenetics showed complex genomic rearrangements in the chromosome 19p13.2p13.12 locus resulting in copy number gains encompassing the entire PRKACA; three patients (one sporadic case and two related cases) were observed with gains consistent with duplications, while two sporadic patients were observed with gains consistent with triplications. Although all five patients presented with ACTH-independent CS, the three sporadic patients had micronodular BAH and underwent bilateral adrenalectomy in early childhood whereas the two related patients, a mother and a son, presented with macronodular BAH as adults. In at least one patient, PRKACA triplication was associated with a more severe phenotype. Conclusions Constitutional chromosomal PRKACA amplification is a recently identified genetic defect associated with CS, a trait that may be inherited in an autosomal dominant manner or occur de novo. Genomic rearrangements can be complex and can result in different copy number states of dosage sensitive genes; e.g. duplication and triplication. PRKACA amplification can lead to variable phenotypes clinically and pathologically, and both micro- and macro-nodular BAH, the latter of which we speculate may depend on the extent of amplification. PMID:25924874

  11. On the sensitivity of long-term magnetotelluric monitoring in Southern Italy and source-dependent robust single station transfer function variability

    NASA Astrophysics Data System (ADS)

    Romano, Gerardo; Balasco, Marianna; Lapenna, Vincenzo; Siniscalchi, Agata; Telesca, Luciano; Tripaldi, Simona

    2014-06-01

    Since 2007, a permanent magnetotelluric (MT) monitoring station has been working in the seismic area of the Agri Valley (Basilicata region, southern Italy) in order to investigate the stability of the MT transfer function. The station was installed in a rural area near the supposed seismogenic fault of the strong earthquake (Mw = 6.9) that struck the Agri Valley in 1857. Analysing about 4 yr of MT data characterized by a low seismic activity, the long-term systematic variations of robust single station MT transfer function estimates were observed in two different sounding period ranges. First, a significant seasonal component of variability for short periods was noted; these short periods were up to 16 s and were linked to variations in wetting/drying of soil moisture in the shallower layers. Second, a connection between the monitored estimates and global geomagnetic activity, Ap index, was found, particularly in the [20-100 s] period range. Analysing remote reference results and tipper estimates in shorter monitoring window, it was shown that such effect cannot be explained by a local or incoherent noise, and a large-scale coherent source should be claimed. We show that this effect is subtle because it produces smooth estimates, satisfying the dispersion relationship between apparent resistivity and phase, with small error bars. As the global geomagnetic activity level increases, robust estimators, like the median value, can be considered as a representative of the estimates due to the natural source, and they tend to stabilize when the Ap index approaches 10. It is also worth noting that our monitored time window includes the recent global minimum of solar activity which occurred in 2009, thus enhancing the estimate dependence on the Ap index.

  12. Time-variable transit time distributions and transport: Theory and application to storage-dependent transport of chloride in a watershed

    NASA Astrophysics Data System (ADS)

    Harman, Ciaran J.

    2015-01-01

    Transport processes and pathways through many hydrodynamic systems vary over time, often driven by variations in total water storage. This paper develops a very general approach to modeling unsteady transport through an arbitrary control volume (such as a watershed) that accounts for temporal variability in the underlying transport dynamics. Controls on the selection of discharge from stored water are encapsulated in probability distributions ΩQ>(ST,t>) of age-ranked storage ST (the volume of water in storage ranked from youngest to oldest). This framework is applied to a long-term record of rainfall and streamflow chloride in a small, humid watershed at Plynlimon, UK. While a time-invariant gamma distribution for ΩQ produced a good fit to data, the fit was significantly improved when the distribution was allowed to vary with catchment storage. However, the variation was inverse to that of a "well-mixed" system where storage has a pure dilution effect. Discharge at high storage was predicted to contain a larger fraction of recent event water than at low storage. The effective volume of storage involved in transport was 3411 mm at mean catchment wetness, but declined by 71 mm per 1 mm of additional catchment storage, while the fraction of event water in discharge increased by 1.4%. This "inverse storage effect" is sufficient to reproduce the observed long-memory 1/f fractal spectral structure of stream chloride. Metrics quantifying the strength and direction of storage effects are proposed as useful signatures, and point toward a unified framework for observing and modeling coupled watershed flow and transport.

  13. Thermal- and pH-Dependent Size Variable Radical Nanoparticles and Its Water Proton Relaxivity for Metal-Free MRI Functional Contrast Agents.

    PubMed

    Morishita, Kosuke; Murayama, Shuhei; Araki, Takeru; Aoki, Ichio; Karasawa, Satoru

    2016-09-16

    For development of the metal-free MRI contrast agents, we prepared the supra-molecular organic radical, TEMPO-UBD, carrying TEMPO radical, as well as the urea, alkyl group, and phenyl ring, which demonstrate self-assembly behaviors using noncovalent bonds in an aqueous solution. In addition, TEMPO-UBD has the tertiary amine and the oligoethylene glycol chains (OEGs) for the function of pH and thermal responsiveness. By dynamic light scattering and transmission electron microscopy imaging, the resulting self-assembly was seen to form the spherical nanoparticles 10-150 nm in size. On heating, interestingly, the nanoparticles showed a lower critical solution temperature (LCST) behavior having two-step variation. This double-LCST behavior is the first such example among the supra-molecules. To evaluate of the ability as MRI contrast agents, the values of proton ((1)H) longitudinal relaxivity (r1) were determined using MRI apparatus. In conditions below and above CAC at pH 7.0, the distinguishable r1 values were estimated to be 0.17 and 0.21 mM(-1) s(1), indicating the suppression of fast tumbling motion of TEMPO moiety in a nanoparticle. Furthermore, r1 values became larger in the order of pH 7.0 > 9.0 > 5.0. Those thermal and pH dependencies indicated the possibility of metal-fee MRI functional contrast agents in the future.

  14. Thermal- and pH-Dependent Size Variable Radical Nanoparticles and Its Water Proton Relaxivity for Metal-Free MRI Functional Contrast Agents.

    PubMed

    Morishita, Kosuke; Murayama, Shuhei; Araki, Takeru; Aoki, Ichio; Karasawa, Satoru

    2016-09-16

    For development of the metal-free MRI contrast agents, we prepared the supra-molecular organic radical, TEMPO-UBD, carrying TEMPO radical, as well as the urea, alkyl group, and phenyl ring, which demonstrate self-assembly behaviors using noncovalent bonds in an aqueous solution. In addition, TEMPO-UBD has the tertiary amine and the oligoethylene glycol chains (OEGs) for the function of pH and thermal responsiveness. By dynamic light scattering and transmission electron microscopy imaging, the resulting self-assembly was seen to form the spherical nanoparticles 10-150 nm in size. On heating, interestingly, the nanoparticles showed a lower critical solution temperature (LCST) behavior having two-step variation. This double-LCST behavior is the first such example among the supra-molecules. To evaluate of the ability as MRI contrast agents, the values of proton ((1)H) longitudinal relaxivity (r1) were determined using MRI apparatus. In conditions below and above CAC at pH 7.0, the distinguishable r1 values were estimated to be 0.17 and 0.21 mM(-1) s(1), indicating the suppression of fast tumbling motion of TEMPO moiety in a nanoparticle. Furthermore, r1 values became larger in the order of pH 7.0 > 9.0 > 5.0. Those thermal and pH dependencies indicated the possibility of metal-fee MRI functional contrast agents in the future. PMID:27541011

  15. Dependence of Device Characteristics of Bulk-Heterojunction Organic Thin-Film Solar Cells on Concentration of Glycerol and Sorbitol Addition in Pedot:. PSS Solutions for Fabricating Buffer Layers

    NASA Astrophysics Data System (ADS)

    Yamaki, Yusuke; Marumoto, Kazuhiro; Fujimori, Takuya; Mori, Tatsuo

    We have investigated the dependence of device characteristics of bulk-heterojunction organic thin-film solar cells on the concentration of glycerol and sorbitol addition in poly(3,4-ethylenedioxy thiophene):poly(4-styrene sulfonate) (PEDOT:PSS) solutions for fabricating buffer layers. The device structure is ITO/buffer/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM)/Al. Glycerol addition is effective for increasing power conversion efficiency (PCE) from 1.25 to 1.41% because of the increase in short-circuit current density (Jsc) without decreasing open-circuit voltage (Voc). On the other hand, sorbitol addition decreases PCE from 1.25 to 1.04%, owing to the decrease in Voc. This difference in Voc behavior is ascribed to different work function of PEDOT:PSS with glycerol and sorbitol treatment.

  16. Phosphazene additives

    DOEpatents

    Harrup, Mason K; Rollins, Harry W

    2013-11-26

    An additive comprising a phosphazene compound that has at least two reactive functional groups and at least one capping functional group bonded to phosphorus atoms of the phosphazene compound. One of the at least two reactive functional groups is configured to react with cellulose and the other of the at least two reactive functional groups is configured to react with a resin, such as an amine resin of a polycarboxylic acid resin. The at least one capping functional group is selected from the group consisting of a short chain ether group, an alkoxy group, or an aryloxy group. Also disclosed are an additive-resin admixture, a method of treating a wood product, and a wood product.

  17. Potlining Additives

    SciTech Connect

    Rudolf Keller

    2004-08-10

    In this project, a concept to improve the performance of aluminum production cells by introducing potlining additives was examined and tested. Boron oxide was added to cathode blocks, and titanium was dissolved in the metal pool; this resulted in the formation of titanium diboride and caused the molten aluminum to wet the carbonaceous cathode surface. Such wetting reportedly leads to operational improvements and extended cell life. In addition, boron oxide suppresses cyanide formation. This final report presents and discusses the results of this project. Substantial economic benefits for the practical implementation of the technology are projected, especially for modern cells with graphitized blocks. For example, with an energy savings of about 5% and an increase in pot life from 1500 to 2500 days, a cost savings of $ 0.023 per pound of aluminum produced is projected for a 200 kA pot.

  18. Classification of red variables

    NASA Technical Reports Server (NTRS)

    Mattei, Janet A.; Foster, Grant; Hurwitz, Leora A.; Malatesta, Kerriann H.; Willson, Lee Anne; Mennessier, Marie-Odile

    1997-01-01

    Red variables are traditionally classified into Mira, semiregular (SR), and slow irregular (L) variables. The Mira variables are the best defined subgroup, whereas SR and L stars are more numerous. The SR subgroup is additionally subdivided into: SRa variables, which feature regular variability with smaller pulsation amplitudes than Miras; SRb variables, which are less regular; SRc variables, which are more luminous; and SRd variables, which are warmer. Relationships within each group are not clear. An analysis of long-term American Association of Variable Star Observers (AAVSP) light curves is reported on. It is found that Mira-type variables are clearly different and distinguishable from SR variables. Similarly, M-type Miras and C-type Miras feature different light curve properties. The M-Miras form a homogeneous group. The pulsations of SR variables are unstable.

  19. Activity of the upstream TATA-less promoter of the p21(Waf1/Cip1) gene depends on transcription factor IIA (TFIIA) in addition to TFIIA-reactive TBP-like protein.

    PubMed

    Suzuki, Hidefumi; Maeda, Ryo; Nakadai, Tomoyoshi; Tamura, Taka-aki

    2014-07-01

    TATA-binding protein-like protein (TLP) binds to transcription factor IIA (TFIIA) with high affinity, although the significance of this binding is poorly understood. In this study, we investigated the role of TFIIA in transcriptional regulation of the p21(Waf1/Cip1) (p21) gene. It has been shown that TLP is indispensable for p53-activated transcription from an upstream TATA-less promoter of the p21 gene. We found that mutant TLPs having decreased TFIIA-binding ability exhibited weakened transcriptional activation function for the upstream promoter. Activity of the upstream promoter was enhanced considerably by an increased amount of TFIIA in a p53-dependent manner, whereas activity of the TATA-containing downstream promoter was enhanced only slightly. TFIIA potentiated the upstream promoter additively with TLP. Although TFIIA is recruited to both promoters, activity of the upstream promoter was much more dependent on TFIIA. Recruitment of TFIIA and TLP to the upstream promoter was augmented in etoposide-treated cells, in which the amount of TFIIA-TLP complex is increased, and TFIIA-reactive TLP was required for the recruitment of both factors. It was confirmed that etoposide-stimulated transcription depends on TLP. We also found that TFIIA-reactive TLP acts to decrease cell growth rate, which can be explained by interaction of the p21 promoter with the transcription factors that we examined. The results of the present study suggest that the upstream TATA-less promoter of p21 needs TFIIA and TFIIA-reactive TLP for p53-dependent transcriptional enhancement.

  20. VERTICAL ATMOSPHERIC STRUCTURE IN A VARIABLE BROWN DWARF: PRESSURE-DEPENDENT PHASE SHIFTS IN SIMULTANEOUS HUBBLE SPACE TELESCOPE-SPITZER LIGHT CURVES

    SciTech Connect

    Buenzli, Esther; Apai, Daniel; Flateau, Davin; Morley, Caroline V.; Showman, Adam P.; Lewis, Nikole K.; Burrows, Adam; Marley, Mark S.; Reid, I. Neill

    2012-12-01

    Heterogeneous clouds or temperature perturbations in rotating brown dwarfs produce variability in the observed flux. We report time-resolved simultaneous observations of the variable T6.5 brown dwarf 2MASS J22282889-431026 over the wavelength ranges 1.1-1.7 {mu}m and broadband 4.5 {mu}m. Spectroscopic observations were taken with Wide Field Camera 3 on board the Hubble Space Telescope and photometry with the Spitzer Space Telescope. The object shows sinusoidal infrared variability with a period of 1.4 hr at most wavelengths with peak-to-peak amplitudes between 1.45% and 5.3% of the mean flux. While the light curve shapes are similar at all wavelengths, their phases differ from wavelength to wavelength with a maximum difference of more than half of a rotational period. We compare the spectra with atmospheric models of different cloud prescriptions, from which we determine the pressure levels probed at different wavelengths. We find that the phase lag increases with decreasing pressure level, or higher altitude. We discuss a number of plausible scenarios that could cause this trend of light curve phase with probed pressure level. These observations are the first to probe heterogeneity in an ultracool atmosphere in both horizontal and vertical directions, and thus are an ideal test case for realistic three-dimensional simulations of the atmospheric structure with clouds in brown dwarfs and extrasolar planets.

  1. A VL-linker-VH Orientation Dependent Single Chain Variable Antibody Fragment Against Rabies Virus G Protein with Enhanced Neutralizing Potency in vivo.

    PubMed

    Cheng, Yue; Li, Zhuang; Xi, Hualong; Gu, Tiejun; Yuan, Ruosen; Chen, Xiaoxu; Jiang, Chunlai; Kong, Wei; Wu, Yongge

    2016-01-01

    Lethal rabies can be prevented effectively by post-exposure prophylactic (PEP) with rabies immunoglobulin (RIG). Single-chain variable fragment (scFv), which is composed of a variable heavy chain (VH) and variable light chain (VL) connected by a peptide linker, may be developed as alternative to RIG for neutralizing rabies virus (RV). However, our previously constructed scFv (FV57S) with the (NH2) VH-linker-VL (COOH) orientation showed a lower neutralizing potency than its parent RIG. This orientation may inhibit FV57S from refolding into an intact and correct conformation. Therefore, the RFV57S protein with a VL-linker-VH orientation was constructed based on FV57S. A HIS tag was incorporated to aid in purification and detection of RFV57S and FV57S. However, abilities of RFV57S and FV57S to bind with the anti-HIS tag mAb were different. Therefore, a novel direct ELISA was established by utilizing a biotin-labeled truncated glycoprotein of RV. Although with similar stability and in vitro neutralizing potency as FV57S, RFV57S showed enhanced binding ability, affinity and in vivo protective efficacy against lethal dose of RV. Our studies support the feasibility of developing a scFv with reversed orientation and provide a novel method for evaluating the binding ability, stability and affinity of engineered antibodies recognizing linear epitope.

  2. Dependence of the microwave radar cross section on ocean surface variables - Comparison of measurements and theory using data from the Frontal Air-Sea Interaction Experiment

    NASA Technical Reports Server (NTRS)

    Weissman, David E.

    1990-01-01

    The purpose of this investigation was to study the ability of theoretical radar cross section (RCS) models to predict the absolute magnitude of the ocean radar cross section under a wide variety of sea and atmospheric conditions. The dependence of the RCS on wind stress (as opposed to wind speed) was also studied. An extensive amount of experimental data was acquired during the Frontal Air-Sea Interaction Experiment. Measurements across an ocean front demonstrated that the vertical polarization and horizontal polarization radar cross section were more strongly dependent on wind stress than on wind magnitude. Current theoretical models for the RCS, based on stress, were tested with this data. In situations where the Bragg scattering theory does not agree with the measured radar cross section (magnitude and angle dependence), revisions are hypothesized and evaluated.

  3. Demographic response to perturbations: the role of compensatory density dependence in a North American duck under variable harvest regulations and changing habitat.

    PubMed

    Péron, Guillaume; Nicolai, Christopher A; Koons, David N

    2012-09-01

    1. Most wild animal populations are subjected to many perturbations, including environmental forcing and anthropogenic mortality. How population size varies in response to these perturbations largely depends on life-history strategy and density regulation. 2. Using the mid-continent population of redhead Aythya americana (a North American diving duck), we investigated the population response to two major perturbations, changes in breeding habitat availability (number of ponds in the study landscape) and changes in harvest regulations directed at managing mortality patterns (bag limit). We used three types of data collected at the continental scale (capture-recovery, population surveys and age- and sex ratios in the harvest) and combined them into integrated population models to assess the interaction between density dependence and the effect of perturbations. 3. We observed a two-way interaction between the effects on fecundity of pond number and population density. Hatch-year female survival was also density dependent. Matrix modelling showed that population booms could occur after especially wet years. However, the effect of moderate variation in pond number was generally offset by density dependence the following year. 4. Mortality patterns were insensitive to changes in harvest regulations and, in males at least, insensitive to density dependence as well. We discuss potential mechanisms for compensation of hunting mortality as well as possible confounding factors. 5. Our results illustrate the interplay of density dependence and environmental variation both shaping population dynamics in a harvested species, which could be generalized to help guide the dual management of habitat and harvest regulations. PMID:22433018

  4. Applying the Transactional Stress and Coping Model to Sickle Cell Disorder and Insulin-Dependent Diabetes Mellitus: Identifying Psychosocial Variables Related to Adjustment and Intervention

    ERIC Educational Resources Information Center

    Hocking, Matthew C.; Lochman, John E.

    2005-01-01

    This review paper examines the literature on psychosocial factors associated with adjustment to sickle cell disease and insulin-dependent diabetes mellitus in children through the framework of the transactional stress and coping (TSC) model. The transactional stress and coping model views adaptation to a childhood chronic illness as mediated by…

  5. Phase dependent loading of Bloch bands and quantum simulation of relativistic wave equation predictions with ultracold atoms in variably shaped optical lattice potentials

    NASA Astrophysics Data System (ADS)

    Grossert, Christopher; Leder, Martin; Weitz, Martin

    2016-10-01

    The dispersion relation of ultracold atoms in variably shaped optical lattices can be tuned to resemble that of a relativistic particle, i.e. be linear instead of the usual nonrelativistic quadratic dispersion relation of a free atom. Cold atoms in such a lattice can be used to carry out quantum simulations of relativistic wave equation predictions. We begin this article by describing a Raman technique that allows to selectively load atoms into a desired Bloch band of the lattice near a band crossing. Subsequently, we review two recent experiments with quasirelativistic rubidium atoms in a bichromatic lattice, demonstrating the analogues of Klein tunnelling and Veselago lensing with ultracold atoms, respectively.

  6. High frequency variability of particle size distribution and its dependency on turbulence over the sea bottom during re-suspension processes

    NASA Astrophysics Data System (ADS)

    Renosh, P. R.; Schmitt, François G.; Loisel, Hubert; Sentchev, Alexei; Mériaux, Xavier

    2014-04-01

    The impact of tidal current, waves and turbulence on particles re-suspension over the sea bottom is studied through Eulerian high frequency measurements of velocity and particle size distribution (PSD) during 5 tidal cycles (65 h) in a coastal environment of the eastern English Channel. High frequency variability of PSD is observed along with the velocity fluctuations. Power spectral analysis shows that turbulent velocity and PSD parameters have similarities in their spectral behaviour over the whole range of examined temporal scales. The low frequency variability of particles is controlled by turbulence (β≃-5/3) and the high frequency is partly driven by dynamical processes impacted by the sea bottom interactions with turbulence (wall turbulence). Stokes number (St), rarely measured in situ, exhibits very low values, emphasizing that these particles can be considered as passive tracers. The effect of tide and waves on turbidity and PSD is highlighted. During slack tide, when the current reaches its minimum value, we observe a higher proportion of small particles compared to larger ones. To a lower extent, high significant wave heights are also associated with a greater concentration of suspended sediments and the presence of larger particles (larger Sauter's diameter DA, and lower PSD slope ξ).

  7. Emissions of nitrogen-containing organic compounds from the burning of herbaceous and arboraceous biomass: Fuel composition dependence and the variability of commonly used nitrile tracers

    NASA Astrophysics Data System (ADS)

    Coggon, Matthew M.; Veres, Patrick R.; Yuan, Bin; Koss, Abigail; Warneke, Carsten; Gilman, Jessica B.; Lerner, Brian M.; Peischl, Jeff; Aikin, Kenneth C.; Stockwell, Chelsea E.; Hatch, Lindsay E.; Ryerson, Thomas B.; Roberts, James M.; Yokelson, Robert J.; Gouw, Joost A.

    2016-09-01

    Volatile organic compounds (VOCs) emitted from residential wood and crop residue burning were measured in Colorado, U.S. When compared to the emissions from crop burning, residential wood burning exhibited markedly lower concentrations of acetonitrile, a commonly used biomass burning tracer. For both herbaceous and arboraceous fuels, the emissions of nitrogen-containing VOCs (NVOCs) strongly depend on the fuel nitrogen content; therefore, low NVOC emissions from residential wood burning result from the combustion of low-nitrogen fuel. Consequently, the emissions of compounds hazardous to human health, such as HNCO and HCN, and the formation of secondary pollutants, such as ozone generated by NOx, are likely to depend on fuel nitrogen. These results also demonstrate that acetonitrile may not be a suitable tracer for domestic burning in urban areas. Wood burning emissions may be best identified through analysis of the emissions profile rather than reliance on a single tracer species.

  8. A method to assess the inter-annual weather-dependent variability in air pollution concentration and deposition based on weather typing

    NASA Astrophysics Data System (ADS)

    Pleijel, Håkan; Grundström, Maria; Karlsson, Gunilla Pihl; Karlsson, Per Erik; Chen, Deliang

    2016-02-01

    Annual anomalies in air pollutant concentrations, and deposition (bulk and throughfall) of sulphate, nitrate and ammonium, in the Gothenburg region, south-west Sweden, were correlated with optimized linear combinations of the yearly frequency of Lamb Weather Types (LWTs) to determine the extent to which the year-to-year variation in pollution exposure can be partly explained by weather related variability. Air concentrations of urban NO2, CO, PM10, as well as O3 at both an urban and a rural monitoring site, and the deposition of sulphate, nitrate and ammonium for the period 1997-2010 were included in the analysis. Linear detrending of the time series was performed to estimate trend-independent anomalies. These estimated anomalies were subtracted from observed annual values. Then the statistical significance of temporal trends with and without LWT adjustment was tested. For the pollutants studied, the annual anomaly was well correlated with the annual LWT combination (R2 in the range 0.52-0.90). Some negative (annual average [NO2], ammonia bulk deposition) or positive (average urban [O3]) temporal trends became statistically significant (p < 0.05) when the LWT adjustment was applied. In all the cases but one (NH4 throughfall, for which no temporal trend existed) the significance of temporal trends became stronger with LWT adjustment. For nitrate and ammonium, the LWT based adjustment explained a larger fraction of the inter-annual variation for bulk deposition than for throughfall. This is probably linked to the longer time scale of canopy related dry deposition processes influencing throughfall being explained to a lesser extent by LWTs than the meteorological factors controlling bulk deposition. The proposed novel methodology can be used by authorities responsible for air pollution management, and by researchers studying temporal trends in pollution, to evaluate e.g. the relative importance of changes in emissions and weather variability in annual air pollution

  9. Ultrasonographic evaluation of the adrenal glands in healthy dogs: repeatability, reproducibility, observer-dependent variability, and the effect of bodyweight, age and sex.

    PubMed

    Mogicato, G; Layssol-Lamour, C; Conchou, F; Diquelou, A; Raharison, F; Sautet, J; Concordet, D

    2011-02-01

    Adrenal length and width were determined from two-dimensional ultrasound longitudinal images. In study 1, 540 measurements of adrenal glands were attempted from five healthy beagle dogs by three different observers with different levels of expertise in ultrasonography, to determine the variability of adrenal gland measurements. Of these, 484 measurements were included in the statistical analysis, since 16 measurements of the left adrenal gland and 40 for the right could not be visualised by the observer. In study 2, a single measurement of both adrenal glands was taken from each of 146 dogs by the most trained observer from study 1, and the effects of different health status (healthy dogs v dogs with non-adrenal diseases), bodyweight, age and sex were assessed. A total of 267 measurements were included in the statistical analysis. The lowest intra- and inter-day coefficient of variation values were observed for the left adrenal gland and by the most trained observer. The health status had no statistically significant effect on adrenal gland length or width, whereas age had a significant effect only for the left adrenal gland (the greater the age, the greater the width or length) and sex had a significant effect only for the right adrenal gland (the width was larger in males and the length larger in females). The bodyweight had a significant effect for the length of both adrenal glands (the greater the bodyweight, the greater the length), but not the width. The differences between sd and coefficient of variation values for the width of the left adrenal gland were not statistically significant between the three observers, whereas they were statistically significant for the right adrenal gland.

  10. Variable Synthetic Capacitance

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1986-01-01

    Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

  11. A psychometric evaluation of adult patients with type 1 (insulin-dependent) diabetes mellitus: prevalence of psychological dysfunction and relationship to demographic variables, metabolic control and complications.

    PubMed

    Winocour, P H; Main, C J; Medlicott, G; Anderson, D C

    1990-08-01

    The relationship between psychosocial traits and glycaemic control and complications was examined in 130 adults (83 men, 47 women) with insulin-dependent diabetes mellitus. Abnormal depression ratings were observed in more women (19.1%) than men (12.0%), p less than 0.01, whilst obsessive symptoms were recorded more frequently in men (41.0 v 21.3%, p less than 0.01). Abnormal anxiety ratings were present in roughly 8-13% of men and women, although a notably low feeling of insecurity rating was observed more frequently in men (56.5%) than in women (38.3% of cases), p less than 0.05. Psychological scores were related to age, employment status and social class, but not to duration of diabetes or glycaemic control. The anxiety, depression and obsessive ratings correlated with one another (rs range 0.24-0.62, all p less than 0.001). Higher anxiety and depression ratings or overt psychological dysfunction was recorded in patients with neuropathic symptoms and signs, impotence, macrovascular disease or proliferative retinopathy. It is concluded that the presence of diabetic complications and adverse social circumstances are more relevant to psychological status than glycaemic control. PMID:2132190

  12. StralSV: assessment of sequence variability within similar 3D structures and application to polio RNA-dependent RNA polymerase

    SciTech Connect

    Zemla, A; Lang, D; Kostova, T; Andino, R; Zhou, C

    2010-11-29

    Most of the currently used methods for protein function prediction rely on sequence-based comparisons between a query protein and those for which a functional annotation is provided. A serious limitation of sequence similarity-based approaches for identifying residue conservation among proteins is the low confidence in assigning residue-residue correspondences among proteins when the level of sequence identity between the compared proteins is poor. Multiple sequence alignment methods are more satisfactory - still, they cannot provide reliable results at low levels of sequence identity. Our goal in the current work was to develop an algorithm that could overcome these difficulties and facilitate the identification of structurally (and possibly functionally) relevant residue-residue correspondences between compared protein structures. Here we present StralSV, a new algorithm for detecting closely related structure fragments and quantifying residue frequency from tight local structure alignments. We apply StralSV in a study of the RNA-dependent RNA polymerase of poliovirus and demonstrate that the algorithm can be used to determine regions of the protein that are relatively unique or that shared structural similarity with structures that are distantly related. By quantifying residue frequencies among many residue-residue pairs extracted from local alignments, one can infer potential structural or functional importance of specific residues that are determined to be highly conserved or that deviate from a consensus. We further demonstrate that considerable detailed structural and phylogenetic information can be derived from StralSV analyses. StralSV is a new structure-based algorithm for identifying and aligning structure fragments that have similarity to a reference protein. StralSV analysis can be used to quantify residue-residue correspondences and identify residues that may be of particular structural or functional importance, as well as unusual or unexpected

  13. High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling.

    PubMed

    Goode, Daniel J; Imbrigiotta, Thomas E; Lacombe, Pierre J

    2014-12-15

    Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently

  14. High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling

    NASA Astrophysics Data System (ADS)

    Goode, Daniel J.; Imbrigiotta, Thomas E.; Lacombe, Pierre J.

    2014-12-01

    Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55 years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently

  15. High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: depth- and strata-dependent spatial variability from rock-core sampling

    USGS Publications Warehouse

    Goode, Daniel J.; Imbrigiotta, Thomas E.; Lacombe, Pierre J.

    2014-01-01

    Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55 years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently

  16. High-resolution delineation of chlorinated volatile organic compounds in a dipping, fractured mudstone: Depth- and strata-dependent spatial variability from rock-core sampling.

    PubMed

    Goode, Daniel J; Imbrigiotta, Thomas E; Lacombe, Pierre J

    2014-12-15

    Synthesis of rock-core sampling and chlorinated volatile organic compound (CVOC) analysis at five coreholes, with hydraulic and water-quality monitoring and a detailed hydrogeologic framework, was used to characterize the fine-scale distribution of CVOCs in dipping, fractured mudstones of the Lockatong Formation of Triassic age, of the Newark Basin in West Trenton, New Jersey. From these results, a refined conceptual model for more than 55years of migration of CVOCs and depth- and strata-dependent rock-matrix contamination was developed. Industrial use of trichloroethene (TCE) at the former Naval Air Warfare Center (NAWC) from 1953 to 1995 resulted in dense non-aqueous phase liquid (DNAPL) TCE and dissolved TCE and related breakdown products, including other CVOCs, in underlying mudstones. Shallow highly weathered and fractured strata overlie unweathered, gently dipping, fractured strata that become progressively less fractured with depth. The unweathered lithology includes black highly fractured (fissile) carbon-rich strata, gray mildly fractured thinly layered (laminated) strata, and light-gray weakly fractured massive strata. CVOC concentrations in water samples pumped from the shallow weathered and highly fractured strata remain elevated near residual DNAPL TCE, but dilution by uncontaminated recharge, and other natural and engineered attenuation processes, have substantially reduced concentrations along flow paths removed from sources and residual DNAPL. CVOCs also were detected in most rock-core samples in source areas in shallow wells. In many locations, lower aqueous concentrations, compared to rock core concentrations, suggest that CVOCs are presently back-diffusing from the rock matrix. Below the weathered and highly fractured strata, and to depths of at least 50 meters (m), groundwater flow and contaminant transport is primarily in bedding-plane-oriented fractures in thin fissile high-carbon strata, and in fractured, laminated strata of the gently

  17. Long-term variability of aerosol optical thickness in Eastern Europe over 2001-2014 according to the measurements at the Moscow MSU MO AERONET site with additional cloud and NO2 correction

    NASA Astrophysics Data System (ADS)

    Chubarova, N. Y.; Poliukhov, A. A.; Gorlova, I. D.

    2015-07-01

    The aerosol properties of the atmosphere were obtained within the framework of the AERONET program at the Moscow State University Meteorological Observatory (Moscow MSU MO) over 2001-2014 period. The quality data control has revealed the necessity of their additional cloud and NO2 correction. The application of cloud correction according to hourly visual cloud observations provides a decrease in average aerosol optical thickness (AOT) at 500 nm of up to 0.03 compared with the standard dataset. We also show that the additional NO2 correction of the AERONET data is needed in large megalopolis, like Moscow, with 12 million residents and the NOx emission rates of about 100 kt yr-1. According to the developed method we estimated monthly mean NO2 content, which provides an additional decrease of 0.01 for AOT at 340 nm, and of about 0.015 - for AOT at 380 and 440 nm. The ratios of NO2 optical thickness to AOT at 380 and 440 nm are about 5-6 % in summer and reach 15-20 % in winter when both factors have similar effects on UV irradiance. Seasonal cycle of AOT at 500 nm is characterized by a noticeable summer and spring maxima, and minimum in winter conditions, changing from 0.08 in December and January up to 0.3 in August. The application of the additional cloud correction removes a local AOT maximum in February, and lowered the December artificial high AOT values. The pronounced negative AOT trends of about -1-5 % yr-1 have been obtained for most months, which could be attributed to the negative trends in emissions (E) of different aerosol precursors of about 116 Gg yr-2 in ESOx, 78 Gg yr-2 in ENMVOC, and 272 Gg yr-2 in ECO over European territory of Russia. No influence of natural factors on temporal AOT variations has been revealed.

  18. Gasoline additives, emissions, and performance

    SciTech Connect

    1995-12-31

    The papers included in this publication deal with the influence of fuel, additive, and hardware changes on a variety of vehicle performance characteristics. Advanced techniques for measuring these performance parameters are also described. Contents include: Fleet test evaluation of gasoline additives for intake valve and combustion chamber deposit clean up; A technique for evaluating octane requirement additives in modern engines on dynamometer test stands; A fleet test of two additive technologies comparing their effects on tailpipe emissions; Investigation into the vehicle exhaust emissions of high percentage ethanol blends; Variability in hydrocarbon speciation measurements at low emission (ULEV) levels; and more.

  19. Buffer additives other than the surfactant sodium dodecyl sulfate for protein separations by capillary electrophoresis.

    PubMed

    Corradini, D

    1997-10-10

    The different compounds utilized as additives to the electrolyte solutions employed in protein capillary zone electrophoresis (CZE) for minimizing protein-capillary wall interactions, for improving selectivity and resolution and for controlling the electroosmotic flow are reviewed. The dependence of the electroosmotic flow on the different variables that can be affected by the incorporation of an additive into the electrolytic solution is discussed. A list of the most effective additives employed for protein separations by CZE is reported in Appendix A.

  20. Iterative Strain-Gage Balance Calibration Data Analysis for Extended Independent Variable Sets

    NASA Technical Reports Server (NTRS)

    Ulbrich, Norbert Manfred

    2011-01-01

    A new method was developed that makes it possible to use an extended set of independent calibration variables for an iterative analysis of wind tunnel strain gage balance calibration data. The new method permits the application of the iterative analysis method whenever the total number of balance loads and other independent calibration variables is greater than the total number of measured strain gage outputs. Iteration equations used by the iterative analysis method have the limitation that the number of independent and dependent variables must match. The new method circumvents this limitation. It simply adds a missing dependent variable to the original data set by using an additional independent variable also as an additional dependent variable. Then, the desired solution of the regression analysis problem can be obtained that fits each gage output as a function of both the original and additional independent calibration variables. The final regression coefficients can be converted to data reduction matrix coefficients because the missing dependent variables were added to the data set without changing the regression analysis result for each gage output. Therefore, the new method still supports the application of the two load iteration equation choices that the iterative method traditionally uses for the prediction of balance loads during a wind tunnel test. An example is discussed in the paper that illustrates the application of the new method to a realistic simulation of temperature dependent calibration data set of a six component balance.

  1. Spontaneous neuronal burst discharges as dependent and independent variables in the maturation of cerebral cortex tissue cultured in vitro: a review of activity-dependent studies in live 'model' systems for the development of intrinsically generated bioelectric slow-wave sleep patterns.

    PubMed

    Corner, Michael A

    2008-11-01

    A survey is presented of recent experiments which utilize spontaneous neuronal spike trains as dependent and/or independent variables in developing cerebral cortex cultures when synaptic transmission is interfered with for varying periods of time. Special attention is given to current difficulties in selecting suitable preparations for carrying out biologically relevant developmental studies, and in applying spike-train analysis methods with sufficient resolution to detect activity-dependent age and treatment effects. A hierarchy of synchronized nested burst discharges which approximate early slow-wave sleep patterns in the intact organism is established as a stable basis for isolated cortex function. The complexity of reported long- and short-term homeostatic responses to experimental interference with synaptic transmission is reviewed, and the crucial role played by intrinsically generated bioelectric activity in the maturation of cortical networks is emphasized.

  2. Response variability of marmoset parvocellular neurons.

    PubMed

    Victor, J D; Blessing, E M; Forte, J D; Buzás, P; Martin, P R

    2007-02-15

    This study concerns the properties of neurons carrying signals for colour vision in primates. We investigated the variability of responses of individual parvocellular lateral geniculate neurons of dichromatic and trichromatic marmosets to drifting sinusoidal luminance and chromatic gratings. Response variability was quantified by the cycle-to-cycle variation in Fourier components of the response. Averaged across the population, the variability at low contrasts was greater than predicted by a Poisson process, and at high contrasts the responses were approximately 40% more variable than responses at low contrasts. The contrast-dependent increase in variability was nevertheless below that expected from the increase in firing rate. Variability falls below the Poisson prediction at high contrast, and intrinsic variability of the spike train decreases as contrast increases. Thus, while deeply modulated responses in parvocellular cells have a larger absolute variability than weakly modulated ones, they have a more favourable signal: noise ratio than predicted by a Poisson process. Similar results were obtained from a small sample of magnocellular and koniocellular ('blue-on') neurons. For parvocellular neurons with pronounced colour opponency, chromatic responses were, on average, less variable (10-15%, p<0.01) than luminance responses of equal magnitude. Conversely, non-opponent parvocellular neurons showed the opposite tendency. This is consistent with a supra-additive noise source prior to combination of cone signals. In summary, though variability of parvocellular neurons is largely independent of the way in which they combine cone signals, the noise characteristics of retinal circuitry may augment specialization of parvocellular neurons to signal luminance or chromatic contrast. PMID:17124265

  3. Blade-order-dependent radiocarbon variability in brown seaweed (Undaria pinnatifida) reflected a cold Oyashio water intrusion event in an embayment of the Sanriku coast, northeastern Japan

    NASA Astrophysics Data System (ADS)

    Satoh, N.; Fukuda, H.; Miyairi, Y.; Yokoyama, Y.; Nagata, T.

    2015-12-01

    Radiocarbon in dissolved inorganic carbon (DIC) in seawater varies greatly, both geographically and with depth. This "reservoir effect" is thought to be reflected in the radiocarbon content (∆14C) of marine organisms, via DIC fixation by primary producers and subsequent trophic transfer. The ∆14C of marine organismal soft tissues might thus provide unique information about their habitats, diets, migration and other environmental histories. However, the effectiveness of this approach has yet to be extensively explored, with data on ∆14C variability in soft tissues of marine organisms being markedly limited. Here we examined whether ∆14C values of individual pinnate blades (leaf-like structures) of brown seaweed (Undaria pinnatifida) reflect the ∆14C of DIC in the water current prevailing at the time of blade formation. The study was conducted in Otsuchi Bay located in the Sanriku coastal region, northeastern Japan, where 14C-depleted cold Oyashio current and warm Tsugaru current (high ∆14C) converge, affecting the physiology and growth of marine organisms growing there. U. pinnatifida individuals cultured in the bay (length of saprophytes, 140-215 cm) were harvested in April 2014 and ∆14C of blades were determined by accelerator mass spectrometry. Younger blades formed after the Oyashio water intrusion had significantly lower ∆14C values compared to older blades formed before the event. The ∆14C values of younger and older blades were generally consistent with the ∆14C of DIC in Oyashio (-60.5 ‰) and Tsugaru (24.9 ‰) waters, respectively. Thus, despite possible turnover of organic carbon in seaweed soft tissues, blade-order-dependent ∆14C variability appeared to strongly reflect the Oyashio intrusion event (radiocarbon shift) in the bay.

  4. Additively Manufactured 3D Porous Ti-6Al-4V Constructs Mimic Trabecular Bone Structure and Regulate Osteoblast Proliferation, Differentiation and Local Factor Production in a Porosity and Surface Roughness Dependent Manner

    PubMed Central

    Cheng, Alice; Humayun, Aiza; Cohen, David J.; Boyan, Barbara D.; Schwartz, Zvi

    2014-01-01

    Additive manufacturing by laser sintering is able to produce high resolution metal constructs for orthopaedic and dental implants. In this study, we used a human trabecular bone template to design and manufacture Ti-6Al-4V constructs with varying porosity via laser sintering. Characterization of constructs revealed interconnected porosities ranging from 15–70% with compressive moduli of 2063–2954 MPa. These constructs with macro porosity were further surface-treated to create a desirable multi-scale micro-/nano-roughness, which has been shown to enhance the osseointegration process. Osteoblasts (MG63 cells) exhibited high viability when grown on the constructs. Proliferation (DNA) and alkaline phosphatase specific activity (ALP), an early differentiation marker, decreased as porosity increased, while osteocalcin (OCN), a late differentiation marker, as well as osteoprotegerin (OPG), vascular endothelial growth factor (VEGF) and bone morphogenetic proteins 2 and 4 (BMP2, BMP4) increased with increasing porosity. 3D constructs with the highest porosity and surface modification supported the greatest osteoblast differentiation and local factor production. These results indicate that additively manufactured 3D porous constructs mimicking human trabecular bone and produced with additional surface treatment can be customized for increased osteoblast response. Increased factors for osteoblast maturation and differentiation on high porosity constructs suggest the enhanced performance of these surfaces for increasing osseointegration in vivo. PMID:25287305

  5. Predicting Group-Level Outcome Variables from Variables Measured at the Individual Level: A Latent Variable Multilevel Model

    ERIC Educational Resources Information Center

    Croon, Marcel A.; van Veldhoven, Marc J. P. M.

    2007-01-01

    In multilevel modeling, one often distinguishes between macro-micro and micro-macro situations. In a macro-micro multilevel situation, a dependent variable measured at the lower level is predicted or explained by variables measured at that lower or a higher level. In a micro-macro multilevel situation, a dependent variable defined at the higher…

  6. Variable Valve Actuation

    SciTech Connect

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release rate and combustion phasing. Figure 1 shows that a systems approach is required for HCCI-like combustion. While the exact requirements remain unclear (and will vary depending on fuel, engine size and application), some form of substantially variable valve actuation is a likely element in such a system. Variable valve actuation, for both intake and exhaust valve events, is a potent tool for controlling the parameters that are critical to HCCI-like combustion and expanding its operational range. Additionally, VVA can be used to optimize the combustion process as well as exhaust temperatures and impact the after treatment system requirements and its associated cost. Delphi Corporation has major manufacturing and product development and applied R&D expertise in the valve train area. Historical R&D experience includes the development of fully variable electro-hydraulic valve train on research engines as well as several generations of mechanical VVA for gasoline systems. This experience has enabled us to evaluate various implementations and determine the strengths and weaknesses of each. While a fully variable electro-hydraulic valve train system might be the 'ideal' solution technically for maximum flexibility in the timing and control of the valve events, its complexity, associated costs, and high power consumption make its implementation on low cost high volume applications unlikely. Conversely, a simple mechanical system might be a low cost solution but not deliver the flexibility required for HCCI operation. After modeling more than 200 variations of the

  7. Evaluating Additive Interaction Using Survival Percentiles.

    PubMed

    Bellavia, Andrea; Bottai, Matteo; Orsini, Nicola

    2016-05-01

    Evaluation of statistical interaction in time-to-event analysis is usually limited to the study of multiplicative interaction, via inclusion of a product term in a Cox proportional-hazard model. Measures of additive interaction are available but seldom used. All measures of interaction in survival analysis, whether additive or multiplicative, are in the metric of hazard, usually assuming that the interaction between two predictors of interest is constant during the follow-up period. We introduce a measure to evaluate additive interaction in survival analysis in the metric of time. This measure can be calculated by evaluating survival percentiles, defined as the time points by which different subpopulations reach the same incidence proportion. Using this approach, the probability of the outcome is fixed and the time variable is estimated. We also show that by using a regression model for the evaluation of conditional survival percentiles, including a product term between the two exposures in the model, interaction is evaluated as a deviation from additivity of the effects. In the simple case of two binary exposures, the product term is interpreted as excess/decrease in survival time (i.e., years, months, days) due to the presence of both exposures. This measure of interaction is dependent on the fraction of events being considered, thus allowing evaluation of how interaction changes during the observed follow-up. Evaluation of interaction in the context of survival percentiles allows deriving a measure of additive interaction without assuming a constant effect over time, overcoming two main limitations of commonly used approaches.

  8. Controlling variability.

    PubMed

    Sanger, Terence D

    2010-11-01

    In human motor control, there is uncertainty in both estimation of initial sensory state and prediction of the outcome of motor commands. With practice, increasing precision can often be achieved, but such precision incurs costs in time, effort, and neural resources. Therefore, motor planning must account for variability, uncertainty, and noise, not just at the endpoint of movement but throughout the movement. The author presents a mathematical basis for understanding the time course of uncertainty during movement. He shows that it is possible to achieve accurate control of the endpoint of a movement even with highly inaccurate and variable controllers. The results provide a first step toward a theory of optimal control for variable, uncertain, and noisy systems that must nevertheless accomplish real-world tasks reliably.

  9. Line and continuum variability in active galaxies

    NASA Astrophysics Data System (ADS)

    Rashed, Y. E.; Eckart, A.; Valencia-S., M.; García-Marín, M.; Busch, G.; Zuther, J.; Horrobin, M.; Zhou, H.

    2015-12-01

    We compared optical spectroscopic and photometric data for 18 active galactic nuclei (AGN) galaxies over two to three epochs, with time intervals of typically 5 to 10 yr. We used the multi-object double spectrograph (MODS) at the Large Binocular Telescope (LBT) and compared the spectra with data taken from the SDSS data base and the literature. We found variations in the forbidden oxygen lines as well as in the hydrogen recombination lines of these sources. For four of the sources we found that, within the calibration uncertainties, the variations in continuum and line spectra of the sources are very small. We argue that it is mainly the difference in black hole mass between the samples that is responsible for the different degree of continuum variability. In addition, we found that for an otherwise constant accretion rate the total line variability (dominated by the narrow line contributions) reverberates in a similar way to the continuum variability with a dependence ΔLline ∝ (ΔLcont)3/2. Because this dependence is predominantly expressed in the narrow line emission, the implication is that the part of the source that dominates the luminosity in the narrow line region must be very compact, with a diameter of the order of at least 10 light-years. A comparison with data from the literature shows that these findings describe the variability characteristics of a total of 61 broad and narrow line sources.

  10. State-variable theories for nonelastic deformation

    SciTech Connect

    Li, C.Y.

    1981-01-01

    The various concepts of mechanical equation of state for nonelastic deformation in crystalline solids, originally proposed for plastic deformation, have been recently extended to describe additional phenomena such as anelastic and microplastic deformation including the Bauschinger effect. It has been demonstrated that it is possible to predict, based on current state variables in a unified way, the mechanical response of a material under an arbitrary loading. Thus, if the evolution laws of the state variables are known, one can describe the behavior of a material for a thermal-mechanical path of interest, for example, during constant load (or stress) creep without relying on specialized theories. Some of the existing theories of mechanical equation of state for nonelastic deformation are reviewed. The establishment of useful forms of mechanical equation of state has to depend on extensive experimentation in the same way as that involved in the development, for example, the ideal gas law. Recent experimental efforts are also reviewed. It has been possible to develop state-variable deformation models based on experimental findings and apply them to creep, cyclic deformation, and other time-dependent deformation. Attempts are being made to correlate the material parameters of the state-variable models with the microstructure of a material. 24 figures.

  11. Which variability?

    PubMed

    Toraldo, Alessio; Luzzatti, Claudio

    2006-02-01

    Drai and Grodzinsky provide a valuable analysis that offers a way of disentangling the effects of Movement and Mood in agrammatic comprehension. However, their mathematical implementation (Beta model) hides theoretically relevant information, i.e., qualitative heterogeneities of performance within the patient sample. This heterogeneity is crucial in the variability debate.

  12. Variability of Neptune

    NASA Astrophysics Data System (ADS)

    Cruikshank, D. P.

    1985-10-01

    Earth based observers of Neptune found that the planet varies in brightness at various wavelengths in ways that suggest that changes occur in the planet's atmosphere on several different time-scales. Global inhomogeneities in high altitude haze distribution that are stable for several days permit measurements of the planet's rotation period (about 18 hours), but this stability sometimes breaks down, obscuring the diurnal lightcurve. In addition, there is an apparent long term variability of the brightness of Neptune in anticorrelation with the cycle of solar activity. This slow variability of low amplitude may be punctuated by outbursts of high altitude condensation of particles in the atmosphere, whose decay time is several months.

  13. Surfing wave climate variability

    NASA Astrophysics Data System (ADS)

    Espejo, Antonio; Losada, Iñigo J.; Méndez, Fernando J.

    2014-10-01

    International surfing destinations are highly dependent on specific combinations of wind-wave formation, thermal conditions and local bathymetry. Surf quality depends on a vast number of geophysical variables, and analyses of surf quality require the consideration of the seasonal, interannual and long-term variability of surf conditions on a global scale. A multivariable standardized index based on expert judgment is proposed for this purpose. This index makes it possible to analyze surf conditions objectively over a global domain. A summary of global surf resources based on a new index integrating existing wave, wind, tides and sea surface temperature databases is presented. According to general atmospheric circulation and swell propagation patterns, results show that west-facing low to middle-latitude coasts are more suitable for surfing, especially those in the Southern Hemisphere. Month-to-month analysis reveals strong seasonal variations in the occurrence of surfable events, enhancing the frequency of such events in the North Atlantic and the North Pacific. Interannual variability was investigated by comparing occurrence values with global and regional modes of low-frequency climate variability such as El Niño and the North Atlantic Oscillation, revealing their strong influence at both the global and the regional scale. Results of the long-term trends demonstrate an increase in the probability of surfable events on west-facing coasts around the world in recent years. The resulting maps provide useful information for surfers, the surf tourism industry and surf-related coastal planners and stakeholders.

  14. Risk assessment of groundwater level variability using variable Kriging methods

    NASA Astrophysics Data System (ADS)

    Spanoudaki, Katerina; Kampanis, Nikolaos A.

    2015-04-01

    Assessment of the water table level spatial variability in aquifers provides useful information regarding optimal groundwater management. This information becomes more important in basins where the water table level has fallen significantly. The spatial variability of the water table level in this work is estimated based on hydraulic head measured during the wet period of the hydrological year 2007-2008, in a sparsely monitored basin in Crete, Greece, which is of high socioeconomic and agricultural interest. Three Kriging-based methodologies are elaborated in Matlab environment to estimate the spatial variability of the water table level in the basin. The first methodology is based on the Ordinary Kriging approach, the second involves auxiliary information from a Digital Elevation Model in terms of Residual Kriging and the third methodology calculates the probability of the groundwater level to fall below a predefined minimum value that could cause significant problems in groundwater resources availability, by means of Indicator Kriging. The Box-Cox methodology is applied to normalize both the data and the residuals for improved prediction results. In addition, various classical variogram models are applied to determine the spatial dependence of the measurements. The Matérn model proves to be the optimal, which in combination with Kriging methodologies provides the most accurate cross validation estimations. Groundwater level and probability maps are constructed to examine the spatial variability of the groundwater level in the basin and the associated risk that certain locations exhibit regarding a predefined minimum value that has been set for the sustainability of the basin's groundwater resources. Acknowledgement The work presented in this paper has been funded by the Greek State Scholarships Foundation (IKY), Fellowships of Excellence for Postdoctoral Studies (Siemens Program), 'A simulation-optimization model for assessing the best practices for the

  15. Investigation of spatio-temporal variability of water uptake in a groundwater-dependent ecosystem using a stable isotope approach (δ18O, δ2H): Pfyn Forest, Switzerland

    NASA Astrophysics Data System (ADS)

    Bertrand, G.; Masini, J.; Goldscheider, N.; Gobat, J. M.; Hunkeler, D.

    2012-04-01

    total humidity of soil, this could be due to rapid infiltration and/or fractionation mainly under equilibrium, i.e. with a relatively high atmospheric humidity, what is possible under forest canopy. Plant water is located under the LMWL in September 2010 when the soil was relatively drought. This evaporative signature could be a clue of water stress. More investigations are however needed to check if this parameter can be used routinely to address water stress. - Secondly, through an analysis of variance, data reveal that at the ecosystem scale, water uptake depends on the site (type of soil, surrounding vegetation, distance from the river), on the growing status (non growing, flowering, mature, water stress) and on the species (poplar, willow, alder, pine). - At last, when focusing at the temporal variability for some individuals, it appears that both rainwater and groundwater may participate to water uptake. The water uptake patterns seem more complicated in mature areas (far from the riverbed) than in frequently flooded zones. This could be due to a more complex soil texture patchwork in the former, and a globally finer soil texture. In particular, it appears that groundwater may sometimes replace rainwater through capillary rise during warm periods.

  16. [Food additives and healthiness].

    PubMed

    Heinonen, Marina

    2014-01-01

    Additives are used for improving food structure or preventing its spoilage, for example. Many substances used as additives are also naturally present in food. The safety of additives is evaluated according to commonly agreed principles. If high concentrations of an additive cause adverse health effects for humans, a limit of acceptable daily intake (ADI) is set for it. An additive is a risk only when ADI is exceeded. The healthiness of food is measured on the basis of nutrient density and scientifically proven effects.

  17. Quantum Backreaction on Classical'' Variables

    SciTech Connect

    Anderson, A. Blackett Laboratory, Imperial College, Prince Consort Rd., London SW7 2BZ )

    1995-01-30

    A mathematically consistent procedure for coupling quasiclassical and quantum variables through coupled Hamilton-Heisenberg equations of motion is derived from a variational principle. During evolution, the quasiclassical variables become entangled with the quantum variables with the result that the value of the quasiclassical variables depends on the quantum state. This provides a formalism to compute the backreaction of any quantum system on a quasiclassical one. In particular, it leads to a natural candidate for a theory of gravity coupled to quantized matter in which the gravitational field is not quantized.

  18. 26 CFR 1.151-2 - Additional exemptions for dependents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... the taxpayer begins, or (2) Is a student, as defined in paragraph (b) of § 1.151-3. No exemption shall... 151(c) (old-age exemptions) and section 151(d) (exemptions for the blind) are allowed only for...

  19. 26 CFR 1.151-2 - Additional exemptions for dependents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the taxpayer begins, or (2) Is a student, as defined in paragraph (b) of § 1.151-3. No exemption shall... 151(c) (old-age exemptions) and section 151(d) (exemptions for the blind) are allowed only for...

  20. Variable spectra of active galaxies

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1988-01-01

    The analysis of EXOSAT spectra of active galaxies are presented. The objects examined for X-ray spectral variability were MR 2251-178 and 3C 120. The results of these investigations are described, as well as additional results on X-ray spectral variability related to EXOSAT observations of active galaxies. Additionally, the dipping X-ray source 4U1624-49 was also investigated.

  1. Variability in subpopulation formation propagates into biocatalytic variability of engineered Pseudomonas putida strains

    PubMed Central

    Lindmeyer, Martin; Jahn, Michael; Vorpahl, Carsten; Müller, Susann; Schmid, Andreas; Bühler, Bruno

    2015-01-01

    Pivotal challenges in industrial biotechnology are the identification and overcoming of cell-to-cell heterogeneity in microbial processes. While the development of subpopulations of isogenic cells in bioprocesses is well described (intra-population variability), a possible variability between genetically identical cultures growing under macroscopically identical conditions (clonal variability) is not. A high such clonal variability has been found for the recombinant expression of the styrene monooxygenase genes styAB from Pseudomonas taiwanensis VLB120 in solvent-tolerant Pseudomonas putida DOT-T1E using the alk-regulatory system from P. putida GPo1. In this study, the oxygenase subunit StyA fused to eGFP was used as readout tool to characterize the population structure in P. putida DOT-T1E regarding recombinant protein content. Flow cytometric analyses revealed that in individual cultures, at least two subpopulations with highly differing recombinant StyA-eGFP protein contents appeared (intra-population variability). Interestingly, subpopulation sizes varied from culture-to-culture correlating with the specific styrene epoxidation activity of cells derived from respective cultures (clonal variability). In addition, flow cytometric cell sorting coupled to plasmid copy number (PCN) determination revealed that detected clonal variations cannot be correlated to the PCN, but depend on the combination of the regulatory system and the host strain employed. This is, to the best of our knowledge, the first work reporting that intra-population variability (with differing protein contents in the presented case study) causes clonal variability of genetically identical cultures. Respective impacts on bioprocess reliability and performance and strategies to overcome respective reliability issues are discussed. PMID:26483771

  2. Temperature fluctuations as a source of brown dwarf variability

    SciTech Connect

    Robinson, Tyler D.; Marley, Mark S.

    2014-04-20

    A number of brown dwarfs are now known to be variable with observed amplitudes as large as 10%-30% at some wavelengths. While spatial inhomogeneities in cloud coverage and thickness are likely responsible for much of the observed variability, it is possible that some of the variations arise from atmospheric temperature fluctuations instead of, or in addition to, clouds. To better understand the role that thermal variability might play we present a case study of brown dwarf variability using a newly developed one-dimensional, time-stepping model of atmospheric thermal structure. We focus on the effects of thermal perturbations, intentionally simplifying the problem through omission of clouds and atmospheric circulation. Model results demonstrate that thermal perturbations occurring deep in the atmosphere (at pressures greater than 10 bar) of a model T-dwarf can be communicated to the upper atmosphere through radiative heating via the windows in near-infrared water opacity. The response time depends on where in the atmosphere a thermal perturbation is introduced. We show that, for certain periodic perturbations, the emission spectrum can have complex time- and wavelength-dependent behaviors, including phase shifts in times of maximum flux observed at different wavelengths. Since different wavelengths probe different levels in the atmosphere, these variations track a wavelength-dependent set of radiative exchanges happening between different atmospheric levels as a perturbation evolves in time. We conclude that thermal—as well as cloud—fluctuations must be considered as possible contributors to the observed brown dwarf variability.

  3. Determination of the specific site occupation of rare earth additions in Y/sub 1/ /sub 7/SM/sub 0/ /sub 6/Lu/sub 0/ /sub 7/Fe/sub 5/O/sub 12/ thin films by the orientation dependence of characteristic x-ray emissions

    SciTech Connect

    Krishnan, K.M.; Rez, P.; Mishra, R.; Thomas, G.

    1983-11-01

    The orientation dependence of characteristic x-ray emissions have been used to determine specific site occupations of Rare Earth additions in epitaxially grown films of Y/sub 1/ /sub 7/Sm/sub 0/ /sub 6/Lu/sub 0/ /sub 7/Fe/sub 5/O/sub 12/. A theoretical formulation based on the assumption of highly localized inner shell excitations was used not only to predict specific site sensitive orientations, but also to refine experimentally observed data employing a constrained least squares analysis to give probabilities for the occupation of the RE additions in the different crystallographic sites. Thus, it has been shown that in this compound the preference for the RE additions is a predominantly octahedral occupation with a probability greater than or equal to 95%. Some of the assumptions and limitations of the technique have also been discussed.

  4. Variable Order and Distributed Order Fractional Operators

    NASA Technical Reports Server (NTRS)

    Lorenzo, Carl F.; Hartley, Tom T.

    2002-01-01

    Many physical processes appear to exhibit fractional order behavior that may vary with time or space. The continuum of order in the fractional calculus allows the order of the fractional operator to be considered as a variable. This paper develops the concept of variable and distributed order fractional operators. Definitions based on the Riemann-Liouville definitions are introduced and behavior of the operators is studied. Several time domain definitions that assign different arguments to the order q in the Riemann-Liouville definition are introduced. For each of these definitions various characteristics are determined. These include: time invariance of the operator, operator initialization, physical realization, linearity, operational transforms. and memory characteristics of the defining kernels. A measure (m2) for memory retentiveness of the order history is introduced. A generalized linear argument for the order q allows the concept of "tailored" variable order fractional operators whose a, memory may be chosen for a particular application. Memory retentiveness (m2) and order dynamic behavior are investigated and applications are shown. The concept of distributed order operators where the order of the time based operator depends on an additional independent (spatial) variable is also forwarded. Several definitions and their Laplace transforms are developed, analysis methods with these operators are demonstrated, and examples shown. Finally operators of multivariable and distributed order are defined in their various applications are outlined.

  5. Variable effort fishing models in random environments.

    PubMed

    Braumann, C A

    1999-03-01

    We study the growth of populations in a random environment subjected to variable effort fishing policies. The models used are stochastic differential equations and the environmental fluctuations may either affect an intrinsic growth parameter or be of the additive noise type. Density-dependent natural growth and fishing policies are of very general form so that our results will be model independent. We obtain conditions on the fishing policies for non-extinction and for non-fixation at the carrying capacity that are very similar to the conditions obtained for the corresponding deterministic model. We also obtain conditions for the existence of stationary distributions (as well as expressions for such distributions) very similar to conditions for the existence of an equilibrium in the corresponding deterministic model. The results obtained provide minimal requirements for the choice of a wise density-dependent fishing policy.

  6. Operant variability: evidence, functions, and theory.

    PubMed

    Neuringer, Allen

    2002-12-01

    Although responses are sometimes easy to predict, at other times responding seems highly variable, unpredictable, or even random. The inability to predict is generally attributed to ignorance of controlling variables, but this article is a review of research showing that the highest levels of behavioral variability may result from identifiable reinforcers contingent on such variability. That is, variability is an operant. Discriminative stimuli and reinforcers control it, resulting in low or high variability, depending on the contingencies. Schedule-of-reinforcement effects are orderly, and choosing to vary or repeat is lawfully governed by relative reinforcement frequencies. The operant nature of variability has important implications. For example, learning, exploring, creating, and problem solving may partly depend on it. Abnormal levels of variability, including those found in psychopathologies such as autism, depression, and attention deficit hyperactivity disorder, may be modified through reinforcement. Operant variability may also help to explain some of the unique attributes of voluntary action.

  7. A generalized additive model for the spatial distribution of snowpack in the Spanish Pyrenees

    NASA Astrophysics Data System (ADS)

    López-Moreno, J. I.; Nogués-Bravo, D.

    2005-10-01

    A generalized additive model (GAM) was used to model the spatial distribution of snow depth in the central Spanish Pyrenees. Statistically significant non-linear relationships were found between distinct location and topographical variables and the average depth of the April snowpack at 76 snow poles from 1985 to 2000. The joint effect of the predictor variables explained more than 73% of the variance of the dependent variable. The performance of the model was assessed by applying a number of quantitative approaches to the residuals from a cross-validation test. The relatively low estimated errors and the possibility of understanding the processes that control snow accumulation, through the response curves of each independent variable, indicate that GAMs may be a useful tool for interpolating local snow depth or other climate parameters.

  8. Quantifying Variability of Avian Colours: Are Signalling Traits More Variable?

    PubMed Central

    Delhey, Kaspar; Peters, Anne

    2008-01-01

    Background Increased variability in sexually selected ornaments, a key assumption of evolutionary theory, is thought to be maintained through condition-dependence. Condition-dependent handicap models of sexual selection predict that (a) sexually selected traits show amplified variability compared to equivalent non-sexually selected traits, and since males are usually the sexually selected sex, that (b) males are more variable than females, and (c) sexually dimorphic traits more variable than monomorphic ones. So far these predictions have only been tested for metric traits. Surprisingly, they have not been examined for bright coloration, one of the most prominent sexual traits. This omission stems from computational difficulties: different types of colours are quantified on different scales precluding the use of coefficients of variation. Methodology/Principal Findings Based on physiological models of avian colour vision we develop an index to quantify the degree of discriminable colour variation as it can be perceived by conspecifics. A comparison of variability in ornamental and non-ornamental colours in six bird species confirmed (a) that those coloured patches that are sexually selected or act as indicators of quality show increased chromatic variability. However, we found no support for (b) that males generally show higher levels of variability than females, or (c) that sexual dichromatism per se is associated with increased variability. Conclusions/Significance We show that it is currently possible to realistically estimate variability of animal colours as perceived by them, something difficult to achieve with other traits. Increased variability of known sexually-selected/quality-indicating colours in the studied species, provides support to the predictions borne from sexual selection theory but the lack of increased overall variability in males or dimorphic colours in general indicates that sexual differences might not always be shaped by similar selective

  9. THE COLOR VARIABILITY OF QUASARS

    SciTech Connect

    Schmidt, Kasper B.; Rix, Hans-Walter; Knecht, Matthias; Hogg, David W.; Shields, Joseph C.; Maoz, Dan; Bovy, Jo

    2012-01-10

    We quantify quasar color variability using an unprecedented variability database-ugriz photometry of 9093 quasars from Sloan Digital Sky Survey (SDSS) Stripe 82, observed over 8 years at {approx}60 epochs each. We confirm previous reports that quasars become bluer when brightening. We find a redshift dependence of this blueing in a given set of bands (e.g., g and r), but show that it is the result of the flux contribution from less-variable or delayed emission lines in the different SDSS bands at different redshifts. After correcting for this effect, quasar color variability is remarkably uniform, and independent not only of redshift, but also of quasar luminosity and black hole mass. The color variations of individual quasars, as they vary in brightness on year timescales, are much more pronounced than the ranges in color seen in samples of quasars across many orders of magnitude in luminosity. This indicates distinct physical mechanisms behind quasar variability and the observed range of quasar luminosities at a given black hole mass-quasar variations cannot be explained by changes in the mean accretion rate. We do find some dependence of the color variability on the characteristics of the flux variations themselves, with fast, low-amplitude, brightness variations producing more color variability. The observed behavior could arise if quasar variability results from flares or ephemeral hot spots in an accretion disk.

  10. Polyimide processing additives

    NASA Technical Reports Server (NTRS)

    Fletcher, James C. (Inventor); Pratt, J. Richard (Inventor); St.clair, Terry L. (Inventor); Stoakley, Diane M. (Inventor); Burks, Harold D. (Inventor)

    1992-01-01

    A process for preparing polyimides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly-(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15 percent by weight of additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA.

  11. Polyimide processing additives

    NASA Technical Reports Server (NTRS)

    Pratt, J. Richard (Inventor); St.clair, Terry L. (Inventor); Stoakley, Diane M. (Inventor); Burks, Harold D. (Inventor)

    1993-01-01

    A process for preparing polyimides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly-(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15 percent by weight of the additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA.

  12. Clinical effects of sulphite additives.

    PubMed

    Vally, H; Misso, N L A; Madan, V

    2009-11-01

    Sulphites are widely used as preservative and antioxidant additives in the food and pharmaceutical industries. Topical, oral or parenteral exposure to sulphites has been reported to induce a range of adverse clinical effects in sensitive individuals, ranging from dermatitis, urticaria, flushing, hypotension, abdominal pain and diarrhoea to life-threatening anaphylactic and asthmatic reactions. Exposure to the sulphites arises mainly from the consumption of foods and drinks that contain these additives; however, exposure may also occur through the use of pharmaceutical products, as well as in occupational settings. While contact sensitivity to sulphite additives in topical medications is increasingly being recognized, skin reactions also occur after ingestion of or parenteral exposure to sulphites. Most studies report a 3-10% prevalence of sulphite sensitivity among asthmatic subjects following ingestion of these additives. However, the severity of these reactions varies, and steroid-dependent asthmatics, those with marked airway hyperresponsiveness, and children with chronic asthma, appear to be at greater risk. In addition to episodic and acute symptoms, sulphites may also contribute to chronic skin and respiratory symptoms. To date, the mechanisms underlying sulphite sensitivity remain unclear, although a number of potential mechanisms have been proposed. Physicians should be aware of the range of clinical manifestations of sulphite sensitivity, as well as the potential sources of exposure. Minor modifications to diet or behaviour lead to excellent clinical outcomes for sulphite-sensitive individuals.

  13. Additional Types of Neuropathy

    MedlinePlus

    ... A A Listen En Español Additional Types of Neuropathy Charcot's Joint Charcot's Joint, also called neuropathic arthropathy, ... can stop bone destruction and aid healing. Cranial Neuropathy Cranial neuropathy affects the 12 pairs of nerves ...

  14. Food Additives and Hyperkinesis

    ERIC Educational Resources Information Center

    Wender, Ester H.

    1977-01-01

    The hypothesis that food additives are causally associated with hyperkinesis and learning disabilities in children is reviewed, and available data are summarized. Available from: American Medical Association 535 North Dearborn Street Chicago, Illinois 60610. (JG)

  15. Smog control fuel additives

    SciTech Connect

    Lundby, W.

    1993-06-29

    A method is described of controlling, reducing or eliminating, ozone and related smog resulting from photochemical reactions between ozone and automotive or industrial gases comprising the addition of iodine or compounds of iodine to hydrocarbon-base fuels prior to or during combustion in an amount of about 1 part iodine per 240 to 10,000,000 parts fuel, by weight, to be accomplished by: (a) the addition of these inhibitors during or after the refining or manufacturing process of liquid fuels; (b) the production of these inhibitors for addition into fuel tanks, such as automotive or industrial tanks; or (c) the addition of these inhibitors into combustion chambers of equipment utilizing solid fuels for the purpose of reducing ozone.

  16. Variability of measured sonic boom signatures

    NASA Technical Reports Server (NTRS)

    Elmer, K. R.; Joshi, M. C.

    1994-01-01

    The topics discussed include the following: atmospheric turbulence; BOOMFILE Database description; BOOMFILE flight conditions; XB-70 Database descriptions; analysis progression; extended database; prediction method; overpressure variability dependence on flight conditions; loudness variability on flight conditions; sonic boom variability in repeat flights; and statistical distributions.

  17. Additive Manufacturing Infrared Inspection

    NASA Technical Reports Server (NTRS)

    Gaddy, Darrell

    2014-01-01

    Additive manufacturing is a rapid prototyping technology that allows parts to be built in a series of thin layers from plastic, ceramics, and metallics. Metallic additive manufacturing is an emerging form of rapid prototyping that allows complex structures to be built using various metallic powders. Significant time and cost savings have also been observed using the metallic additive manufacturing compared with traditional techniques. Development of the metallic additive manufacturing technology has advanced significantly over the last decade, although many of the techniques to inspect parts made from these processes have not advanced significantly or have limitations. Several external geometry inspection techniques exist such as Coordinate Measurement Machines (CMM), Laser Scanners, Structured Light Scanning Systems, or even traditional calipers and gages. All of the aforementioned techniques are limited to external geometry and contours or must use a contact probe to inspect limited internal dimensions. This presentation will document the development of a process for real-time dimensional inspection technique and digital quality record of the additive manufacturing process using Infrared camera imaging and processing techniques.

  18. Additive-free digital microfluidics.

    PubMed

    Freire, Sergio L S; Tanner, Brendan

    2013-07-16

    Digital microfluidics, a technique for manipulation of droplets, is becoming increasingly important for the development of miniaturized platforms for laboratory processes. Despite the enthusiasm, droplet motion is frequently hindered by the desorption of proteins or other analytes to surfaces. Current approaches to minimize this unwanted surface fouling involve the addition of extra species to the droplet or its surroundings, which might be problematic depending on the droplet content. Here, a new strategy is introduced to move droplets containing cells and other analytes on solid substrates, without extra moieties; in particular, droplets with bovine serum albumin could be moved at a concentration 2000 times higher than previously reported (without additives). This capability is achieved by using a soot-based superamphiphobic surface combined with a new device geometry, which favors droplet rolling. Contrasting with electrowetting, wetting forces are not required for droplet motion.

  19. Postural constraints on movement variability.

    PubMed

    Lametti, Daniel R; Ostry, David J

    2010-08-01

    Movements are inherently variable. When we move to a particular point in space, a cloud of final limb positions is observed around the target. Previously we noted that patterns of variability at the end of movement to a circular target were not circular, but instead reflected patterns of limb stiffness-in directions where limb stiffness was high, variability in end position was low, and vice versa. Here we examine the determinants of variability at movement end in more detail. To do this, we have subjects move the handle of a robotic device from different starting positions into a circular target. We use position servocontrolled displacements of the robot's handle to measure limb stiffness at the end of movement and we also record patterns of end position variability. To examine the effect of change in posture on movement variability, we use a visual motor transformation in which we change the limb configuration and also the actual movement target, while holding constant the visual display. We find that, regardless of movement direction, patterns of variability at the end of movement vary systematically with limb configuration and are also related to patterns of limb stiffness, which are likewise configuration dependent. The result suggests that postural configuration determines the base level of movement variability, on top of which control mechanisms can act to further alter variability.

  20. The importance of being variable

    PubMed Central

    Garrett, Douglas D.; Kovacevic, Natasa; McIntosh, Anthony R.; Grady, Cheryl L.

    2011-01-01

    New work suggests that blood oxygen level-dependent (BOLD) signal variability can be a much more powerful index of human age than mean activation, and that older brains are actually less variable than younger brains (Garrett, Kovacevic, McIntosh, & Grady, 2010). However, little is known of how BOLD variability and task performance may relate. In the current study, we examined BOLD variability in relation to age, and reaction time (RT) speed and consistency in healthy younger (20–30 years) and older (56–85 years) adults on three cognitive tasks (perceptual matching, attentional cueing, and delayed match-to-sample). Results indicated that younger, faster, and more consistent performers exhibited significantly higher brain variability across tasks, and showed greater variability-based regional differentiation compared to older, poorer performing adults. Also, when we compared brain variability- and typical mean-based effects, the respective spatial patterns were essentially orthogonal across brain measures, and any regions that did overlap were largely opposite in directionality of effect. These findings help establish the functional basis of BOLD variability, and further support the statistical and spatial differentiation between BOLD variability and BOLD mean. We thus argue that the precise nature of relations between aging, cognition, and brain function is under-appreciated by using mean-based brain measures exclusively. PMID:21430150

  1. Phenylethynyl Containing Reactive Additives

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2002-01-01

    Phenylethynyl containing reactive additives were prepared from aromatic diamine, containing phenylethvnvl groups and various ratios of phthalic anhydride and 4-phenylethynviphthalic anhydride in glacial acetic acid to form the imide in one step or in N-methyl-2-pvrrolidinone to form the amide acid intermediate. The reactive additives were mixed in various amounts (10% to 90%) with oligomers containing either terminal or pendent phenylethynyl groups (or both) to reduce the melt viscosity and thereby enhance processability. Upon thermal cure, the additives react and become chemically incorporated into the matrix and effect an increase in crosslink density relative to that of the host resin. This resultant increase in crosslink density has advantageous consequences on the cured resin properties such as higher glass transition temperature and higher modulus as compared to that of the host resin.

  2. Index for Wind Power Variability

    SciTech Connect

    Kiviluoma, Juha; Holttinen, Hannele; Cutululis, Nicolaos Antonio; Litong-Palima, Marisciel; Scharff, Richard; Milligan, Michael; Weir, David Edward

    2014-11-13

    Variability of large scale wind power generation is dependent on several factors: characteristics of installed wind power plants, size of the area where the plants are installed, geographic dispersion within that area and its weather regime(s). Variability can be described by ramps in power generation, i.e. changes from time period to time period. Given enough data points, it can be described with a probability density function. This approach focuses on two dimensions of variability: duration of the ramp and probability distribution. This paper proposes an index based on these two dimensions to enable comparisons and characterizations of variability under different conditions. The index is tested with real, large scale wind power generation data from several countries. Considerations while forming an index are discussed, as well as the main results regarding what the drivers of variability experienced for different data.

  3. Decisions Concerning Directional Dependence

    ERIC Educational Resources Information Center

    von Eye, Alexander; DeShon, Richard P.

    2012-01-01

    In this rejoinder, von Eye and DeShon discuss the decision strategies proposed in their original article ("Directional Dependence in Developmental Research," this issue), as well as the ones proposed by the authors of the commentary (Pornprasertmanit and Little, "Determining Directional Dependency in Causal Associations," this issue). In addition,…

  4. TabVar: Tabulated Variables

    2015-12-15

    TabVar: A Python library for manipulating datasets in the form of tabulated variables. Tables in tabvar contain many columns representing independent variables, but exactly one distinguished column for the dependent variable. Having a single distinguished column allows a natural lifting of arithmetic operators to tables, much (and in fact fully generalizing) multidimensional array arithmetic. The convenient syntax of whole-table arithmetic, along with the usual operations of filtering and aggregation, and all in the setting ofmore » python's interactive REPL allows for rapid exploration of datasets.« less

  5. TabVar: Tabulated Variables

    SciTech Connect

    Bachan, John

    2015-12-15

    TabVar: A Python library for manipulating datasets in the form of tabulated variables. Tables in tabvar contain many columns representing independent variables, but exactly one distinguished column for the dependent variable. Having a single distinguished column allows a natural lifting of arithmetic operators to tables, much (and in fact fully generalizing) multidimensional array arithmetic. The convenient syntax of whole-table arithmetic, along with the usual operations of filtering and aggregation, and all in the setting of python's interactive REPL allows for rapid exploration of datasets.

  6. Multifunctional fuel additives

    SciTech Connect

    Baillargeon, D.J.; Cardis, A.B.; Heck, D.B.

    1991-03-26

    This paper discusses a composition comprising a major amount of a liquid hydrocarbyl fuel and a minor low-temperature flow properties improving amount of an additive product of the reaction of a suitable diol and product of a benzophenone tetracarboxylic dianhydride and a long-chain hydrocarbyl aminoalcohol.

  7. Biobased lubricant additives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fully biobased lubricants are those formulated using all biobased ingredients, i.e. biobased base oils and biobased additives. Such formulations provide the maximum environmental, safety, and economic benefits expected from a biobased product. Currently, there are a number of biobased base oils that...

  8. Additive Manufacturing in Production: A Study Case Applying Technical Requirements

    NASA Astrophysics Data System (ADS)

    Ituarte, Iñigo Flores; Coatanea, Eric; Salmi, Mika; Tuomi, Jukka; Partanen, Jouni

    Additive manufacturing (AM) is expanding the manufacturing capabilities. However, quality of AM produced parts is dependent on a number of machine, geometry and process parameters. The variability of these parameters affects the manufacturing drastically and therefore standardized processes and harmonized methodologies need to be developed to characterize the technology for end use applications and enable the technology for manufacturing. This research proposes a composite methodology integrating Taguchi Design of Experiments, multi-objective optimization and statistical process control, to optimize the manufacturing process and fulfil multiple requirements imposed to an arbitrary geometry. The proposed methodology aims to characterize AM technology depending upon manufacturing process variables as well as to perform a comparative assessment of three AM technologies (Selective Laser Sintering, Laser Stereolithography and Polyjet). Results indicate that only one machine, laser-based Stereolithography, was feasible to fulfil simultaneously macro and micro level geometrical requirements but mechanical properties were not at required level. Future research will study a single AM system at the time to characterize AM machine technical capabilities and stimulate pre-normative initiatives of the technology for end use applications.

  9. Vinyl capped addition polyimides

    NASA Technical Reports Server (NTRS)

    Vannucci, Raymond D. (Inventor); Malarik, Diane C. (Inventor); Delvigs, Peter (Inventor)

    1991-01-01

    Polyimide resins (PMR) are generally useful where high strength and temperature capabilities are required (at temperatures up to about 700 F). Polyimide resins are particularly useful in applications such as jet engine compressor components, for example, blades, vanes, air seals, air splitters, and engine casing parts. Aromatic vinyl capped addition polyimides are obtained by reacting a diamine, an ester of tetracarboxylic acid, and an aromatic vinyl compound. Low void materials with improved oxidative stability when exposed to 700 F air may be fabricated as fiber reinforced high molecular weight capped polyimide composites. The aromatic vinyl capped polyimides are provided with a more aromatic nature and are more thermally stable than highly aliphatic, norbornenyl-type end-capped polyimides employed in PMR resins. The substitution of aromatic vinyl end-caps for norbornenyl end-caps in addition polyimides results in polymers with improved oxidative stability.

  10. Tackifier for addition polyimides

    NASA Technical Reports Server (NTRS)

    Butler, J. M.; St.clair, T. L.

    1980-01-01

    A modification to the addition polyimide, LaRC-160, was prepared to improve tack and drape and increase prepeg out-time. The essentially solventless, high viscosity laminating resin is synthesized from low cost liquid monomers. The modified version takes advantage of a reactive, liquid plasticizer which is used in place of solvent and helps solve a major problem of maintaining good prepeg tack and drape, or the ability of the prepeg to adhere to adjacent plies and conform to a desired shape during the lay up process. This alternate solventless approach allows both longer life of the polymer prepeg and the processing of low void laminates. This approach appears to be applicable to all addition polyimide systems.

  11. Electrophilic addition of astatine

    SciTech Connect

    Norseev, Yu.V.; Vasaros, L.; Nhan, D.D.; Huan, N.K.

    1988-03-01

    It has been shown for the first time that astatine is capable of undergoing addition reactions to unsaturated hydrocarbons. A new compound of astatine, viz., ethylene astatohydrin, has been obtained, and its retention numbers of squalane, Apiezon, and tricresyl phosphate have been found. The influence of various factors on the formation of ethylene astatohydrin has been studied. It has been concluded on the basis of the results obtained that the univalent cations of astatine in an acidic medium is protonated hypoastatous acid.

  12. Texting Dependence, iPod Dependence, and Delay Discounting.

    PubMed

    Ferraro, F Richard; Weatherly, Jeffrey N

    2016-01-01

    We gave 127 undergraduates questionnaires about their iPod and texting dependence and 2 hypothetical delay discounting scenarios related to free downloaded songs and free texting for life. Using regression analyses we found that when iPod dependence was the dependent variable, Text2-excessive use, Text4-psychological and behavioral symptoms, iPod2-excessive use, and iPod3-relationship disruption were significant predictors of discounting. When texting dependence was the dependent variable, Text4-psychological and behavioral symptoms and iPod3-relationship disruption were significant predictors of discounting. These are the first data to show that delay discounting relates to certain aspects of social media, namely iPod and texting dependence. These data also show that across these 2 dependencies, both psychological and behavioral symptoms and relationship disruptions are affected. PMID:27424418

  13. Texting Dependence, iPod Dependence, and Delay Discounting.

    PubMed

    Ferraro, F Richard; Weatherly, Jeffrey N

    2016-01-01

    We gave 127 undergraduates questionnaires about their iPod and texting dependence and 2 hypothetical delay discounting scenarios related to free downloaded songs and free texting for life. Using regression analyses we found that when iPod dependence was the dependent variable, Text2-excessive use, Text4-psychological and behavioral symptoms, iPod2-excessive use, and iPod3-relationship disruption were significant predictors of discounting. When texting dependence was the dependent variable, Text4-psychological and behavioral symptoms and iPod3-relationship disruption were significant predictors of discounting. These are the first data to show that delay discounting relates to certain aspects of social media, namely iPod and texting dependence. These data also show that across these 2 dependencies, both psychological and behavioral symptoms and relationship disruptions are affected.

  14. Functional Generalized Additive Models.

    PubMed

    McLean, Mathew W; Hooker, Giles; Staicu, Ana-Maria; Scheipl, Fabian; Ruppert, David

    2014-01-01

    We introduce the functional generalized additive model (FGAM), a novel regression model for association studies between a scalar response and a functional predictor. We model the link-transformed mean response as the integral with respect to t of F{X(t), t} where F(·,·) is an unknown regression function and X(t) is a functional covariate. Rather than having an additive model in a finite number of principal components as in Müller and Yao (2008), our model incorporates the functional predictor directly and thus our model can be viewed as the natural functional extension of generalized additive models. We estimate F(·,·) using tensor-product B-splines with roughness penalties. A pointwise quantile transformation of the functional predictor is also considered to ensure each tensor-product B-spline has observed data on its support. The methods are evaluated using simulated data and their predictive performance is compared with other competing scalar-on-function regression alternatives. We illustrate the usefulness of our approach through an application to brain tractography, where X(t) is a signal from diffusion tensor imaging at position, t, along a tract in the brain. In one example, the response is disease-status (case or control) and in a second example, it is the score on a cognitive test. R code for performing the simulations and fitting the FGAM can be found in supplemental materials available online.

  15. Attitude Towards Physics and Additional Mathematics Achievement Towards Physics Achievement

    ERIC Educational Resources Information Center

    Veloo, Arsaythamby; Nor, Rahimah; Khalid, Rozalina

    2015-01-01

    The purpose of this research is to identify the difference in students' attitude towards Physics and Additional Mathematics achievement based on gender and relationship between attitudinal variables towards Physics and Additional Mathematics achievement with achievement in Physics. This research focused on six variables, which is attitude towards…

  16. Operant Variability: A Conceptual Analysis

    PubMed Central

    de Souza Barba, Lourenço.

    2012-01-01

    Some researchers claim that variability is an operant dimension of behavior. The present paper reviews the concept of operant behavior and emphasizes that differentiation is the behavioral process that demonstrates an operant relation. Differentiation is conceived as change in the overlap between two probability distributions: the distribution of reinforcement probability as a function of some response property (S distribution) and the probability distribution of the response property itself (R distribution). This concept implies that the differentiation process can be measured only if S distribution and R distribution are both established on the same response property. To determine whether the differentially reinforced behavioral variability fits the proposed concept of operant behavior, I examine the main procedures (lag n and threshold procedures) and the main dependent variable (U value) employed in the studies of operant variability. Because lag n and threshold procedures establish their S distributions on properties distinct from U value, differentiation cannot be measured over the change in U value. I conclude that studies of operant variability have failed to provide a direct demonstration that variability is an operant dimension of behavior. Hence, studies in which measures of variability provide a basis to measure differentiation can better support the claim that variability is an operant dimension of behavior. PMID:23450082

  17. Modeling Errors in Daily Precipitation Measurements: Additive or Multiplicative?

    NASA Technical Reports Server (NTRS)

    Tian, Yudong; Huffman, George J.; Adler, Robert F.; Tang, Ling; Sapiano, Matthew; Maggioni, Viviana; Wu, Huan

    2013-01-01

    The definition and quantification of uncertainty depend on the error model used. For uncertainties in precipitation measurements, two types of error models have been widely adopted: the additive error model and the multiplicative error model. This leads to incompatible specifications of uncertainties and impedes intercomparison and application.In this letter, we assess the suitability of both models for satellite-based daily precipitation measurements in an effort to clarify the uncertainty representation. Three criteria were employed to evaluate the applicability of either model: (1) better separation of the systematic and random errors; (2) applicability to the large range of variability in daily precipitation; and (3) better predictive skills. It is found that the multiplicative error model is a much better choice under all three criteria. It extracted the systematic errors more cleanly, was more consistent with the large variability of precipitation measurements, and produced superior predictions of the error characteristics. The additive error model had several weaknesses, such as non constant variance resulting from systematic errors leaking into random errors, and the lack of prediction capability. Therefore, the multiplicative error model is a better choice.

  18. Variability Study of the S5 Sample

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Cui, Lang; Liu, Xiang; Ding, Zhen; Song, Hua-Gang

    2014-09-01

    We present the results of flux density monitoring of the S5 sample at 5 GHz with the Urumqi 25-m radio telescope during Dec. 2008 and Nov. 2009. Most sources exhibited >2% rms variation in our one-year monitoring. Twenty-five highly variable sources were detected at a confidence level of 99%. Weaker sources show larger amplitude of variability. Sources that have a steep spectral index are not as variable in flux density as the flat spectrum objects. No galactic dependent variability was found. Supplemental IDV observations for several strong variables were performed in order to search for possible rapid variability, and to compare variability on different time-scales. The absence of short time-scale variability in S5 0633+73 indicates that mid time-scale variability is a main source of intrinsic origin.

  19. Q2DSTD NMR deciphers epitope-mapping variability for peptide recognition of integrin αvβ6† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5ob01237f Click here for additional data file.

    PubMed Central

    Sorge, Jessica L.; Wagstaff, Jane L.; Rowe, Michelle L.

    2015-01-01

    Integrin αvβ6 is a cell surface arginine-glycine-aspartic acid (RGD)-specific heterodimeric glycoprotein that is only expressed on epithelia during processes of tissue remodelling, including cancer. The specificity and molecular nature of interactions toward this integrin are poorly understood and new insights into such processes are important to cell biologists and pharmaceutical drug discovery. This study demonstrates the application of quantitative two-dimensional saturation transfer (Q2DSTD) NMR to obtain precise details of peptide interactions with integrin αvβ6 and their correlation to specificity for the integrin. This approach highlights subtle but significant differences in ligand contact by three related 21-mer peptides: FMDV2, an αvβ6 specific peptide and DBD1 and LAP2T1 peptides that bind many αv integrins in addition to αvβ6. FMDV2 and DBD1 differ only by the cyclisation of DBD1; a process that removes αvβ6 specificity. Q2DSTD NMR demonstrates these peptides experience significantly different interactions with the integrin; FMDV contacts primarily through four residues: 6Leu, 10Leu, 12Val and 13Leu, whereas DBD1 and LAP2T1 have more widespread contacts across their sequences. Q2DSTD NMR combined two-dimensional STD with quantitation by considering the relaxation of the ligand (CRL) to provide precise ligand contact information. This study also examines the role of CRL in the Q2DSTD process and how quantitation modifies STD data and unravels epitope-mapping variability to provide precise results that differentiate interactions at the atomic level for each peptide. PMID:26119198

  20. Harvested populations are more variable only in more variable environments.

    PubMed

    Cameron, Tom C; O'Sullivan, Daniel; Reynolds, Alan; Hicks, Joseph P; Piertney, Stuart B; Benton, Tim G

    2016-06-01

    The interaction between environmental variation and population dynamics is of major importance, particularly for managed and economically important species, and especially given contemporary changes in climate variability. Recent analyses of exploited animal populations contested whether exploitation or environmental variation has the greatest influence on the stability of population dynamics, with consequences for variation in yield and extinction risk. Theoretical studies however have shown that harvesting can increase or decrease population variability depending on environmental variation, and requested controlled empirical studies to test predictions. Here, we use an invertebrate model species in experimental microcosms to explore the interaction between selective harvesting and environmental variation in food availability in affecting the variability of stage-structured animal populations over 20 generations. In a constant food environment, harvesting adults had negligible impact on population variability or population size, but in the variable food environments, harvesting adults increased population variability and reduced its size. The impact of harvesting on population variability differed between proportional and threshold harvesting, between randomly and periodically varying environments, and at different points of the time series. Our study suggests that predicting the responses to selective harvesting is sensitive to the demographic structures and processes that emerge in environments with different patterns of environmental variation. PMID:27516873

  1. Performance Boosting Additive

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Mainstream Engineering Corporation was awarded Phase I and Phase II contracts from Goddard Space Flight Center's Small Business Innovation Research (SBIR) program in early 1990. With support from the SBIR program, Mainstream Engineering Corporation has developed a unique low cost additive, QwikBoost (TM), that increases the performance of air conditioners, heat pumps, refrigerators, and freezers. Because of the energy and environmental benefits of QwikBoost, Mainstream received the Tibbetts Award at a White House Ceremony on October 16, 1997. QwikBoost was introduced at the 1998 International Air Conditioning, Heating, and Refrigeration Exposition. QwikBoost is packaged in a handy 3-ounce can (pressurized with R-134a) and will be available for automotive air conditioning systems in summer 1998.

  2. Sewage sludge additive

    NASA Technical Reports Server (NTRS)

    Kalvinskas, J. J.; Mueller, W. A.; Ingham, J. D. (Inventor)

    1980-01-01

    The additive is for a raw sewage treatment process of the type where settling tanks are used for the purpose of permitting the suspended matter in the raw sewage to be settled as well as to permit adsorption of the dissolved contaminants in the water of the sewage. The sludge, which settles down to the bottom of the settling tank is extracted, pyrolyzed and activated to form activated carbon and ash which is mixed with the sewage prior to its introduction into the settling tank. The sludge does not provide all of the activated carbon and ash required for adequate treatment of the raw sewage. It is necessary to add carbon to the process and instead of expensive commercial carbon, coal is used to provide the carbon supplement.

  3. Perspectives on Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Bourell, David L.

    2016-07-01

    Additive manufacturing (AM) has skyrocketed in visibility commercially and in the public sector. This article describes the development of this field from early layered manufacturing approaches of photosculpture, topography, and material deposition. Certain precursors to modern AM processes are also briefly described. The growth of the field over the last 30 years is presented. Included is the standard delineation of AM technologies into seven broad categories. The economics of AM part generation is considered, and the impacts of the economics on application sectors are described. On the basis of current trends, the future outlook will include a convergence of AM fabricators, mass-produced AM fabricators, enabling of topology optimization designs, and specialization in the AM legal arena. Long-term developments with huge impact are organ printing and volume-based printing.

  4. Sarks as additional fermions

    NASA Astrophysics Data System (ADS)

    Agrawal, Jyoti; Frampton, Paul H.; Jack Ng, Y.; Nishino, Hitoshi; Yasuda, Osamu

    1991-03-01

    An extension of the standard model is proposed. The gauge group is SU(2) X ⊗ SU(3) C ⊗ SU(2) S ⊗ U(1) Q, where all gauge symmetries are unbroken. The colour and electric charge are combined with SU(2) S which becomes strongly coupled at approximately 500 GeV and binds preons to form fermionic and vector bound states. The usual quarks and leptons are singlets under SU(2) X but additional fermions, called sarks. transform under it and the electroweak group. The present model explains why no more than three light quark-lepton families can exist. Neutral sark baryons, called narks, are candidates for the cosmological dark matter having the characteristics designed for WIMPS. Further phenomenological implications of sarks are analyzed i including electron-positron annihilation. Z 0 decay, flavor-changing neutral currents. baryon-number non-conservation, sarkonium and the neutron electric dipole moment.

  5. [Affective dependency].

    PubMed

    Scantamburlo, G; Pitchot, W; Ansseau, M

    2013-01-01

    Affective dependency is characterized by emotional distress (insecure attachment) and dependency to another person with a low self-esteem and reassurance need. The paper proposes a reflection on the definition of emotional dependency and the confusion caused by various denominations. Overprotective and authoritarian parenting, cultural and socio-environmental factors may contribute to the development of dependent personality. Psychological epigenetic factors, such as early socio-emotional trauma could on neuronal circuits in prefronto-limbic regions that are essential for emotional behaviour.We also focus on the interrelations between dependent personality, domestic violence and addictions. The objective for the clinician is to propose a restoration of self-esteem and therapeutic strategies focused on autonomy.

  6. [Affective dependency].

    PubMed

    Scantamburlo, G; Pitchot, W; Ansseau, M

    2013-01-01

    Affective dependency is characterized by emotional distress (insecure attachment) and dependency to another person with a low self-esteem and reassurance need. The paper proposes a reflection on the definition of emotional dependency and the confusion caused by various denominations. Overprotective and authoritarian parenting, cultural and socio-environmental factors may contribute to the development of dependent personality. Psychological epigenetic factors, such as early socio-emotional trauma could on neuronal circuits in prefronto-limbic regions that are essential for emotional behaviour.We also focus on the interrelations between dependent personality, domestic violence and addictions. The objective for the clinician is to propose a restoration of self-esteem and therapeutic strategies focused on autonomy. PMID:23888587

  7. Biological data analysis as an information theory problem: multivariable dependence measures and the shadows algorithm.

    PubMed

    Sakhanenko, Nikita A; Galas, David J

    2015-11-01

    Information theory is valuable in multiple-variable analysis for being model-free and nonparametric, and for the modest sensitivity to undersampling. We previously introduced a general approach to finding multiple dependencies that provides accurate measures of levels of dependency for subsets of variables in a data set, which is significantly nonzero only if the subset of variables is collectively dependent. This is useful, however, only if we can avoid a combinatorial explosion of calculations for increasing numbers of variables.  The proposed dependence measure for a subset of variables, τ, differential interaction information, Δ(τ), has the property that for subsets of τ some of the factors of Δ(τ) are significantly nonzero, when the full dependence includes more variables. We use this property to suppress the combinatorial explosion by following the "shadows" of multivariable dependency on smaller subsets. Rather than calculating the marginal entropies of all subsets at each degree level, we need to consider only calculations for subsets of variables with appropriate "shadows." The number of calculations for n variables at a degree level of d grows therefore, at a much smaller rate than the binomial coefficient (n, d), but depends on the parameters of the "shadows" calculation. This approach, avoiding a combinatorial explosion, enables the use of our multivariable measures on very large data sets. We demonstrate this method on simulated data sets, and characterize the effects of noise and sample numbers. In addition, we analyze a data set of a few thousand mutant yeast strains interacting with a few thousand chemical compounds. PMID:26335709

  8. Biological data analysis as an information theory problem: multivariable dependence measures and the shadows algorithm.

    PubMed

    Sakhanenko, Nikita A; Galas, David J

    2015-11-01

    Information theory is valuable in multiple-variable analysis for being model-free and nonparametric, and for the modest sensitivity to undersampling. We previously introduced a general approach to finding multiple dependencies that provides accurate measures of levels of dependency for subsets of variables in a data set, which is significantly nonzero only if the subset of variables is collectively dependent. This is useful, however, only if we can avoid a combinatorial explosion of calculations for increasing numbers of variables.  The proposed dependence measure for a subset of variables, τ, differential interaction information, Δ(τ), has the property that for subsets of τ some of the factors of Δ(τ) are significantly nonzero, when the full dependence includes more variables. We use this property to suppress the combinatorial explosion by following the "shadows" of multivariable dependency on smaller subsets. Rather than calculating the marginal entropies of all subsets at each degree level, we need to consider only calculations for subsets of variables with appropriate "shadows." The number of calculations for n variables at a degree level of d grows therefore, at a much smaller rate than the binomial coefficient (n, d), but depends on the parameters of the "shadows" calculation. This approach, avoiding a combinatorial explosion, enables the use of our multivariable measures on very large data sets. We demonstrate this method on simulated data sets, and characterize the effects of noise and sample numbers. In addition, we analyze a data set of a few thousand mutant yeast strains interacting with a few thousand chemical compounds.

  9. Biological Data Analysis as an Information Theory Problem: Multivariable Dependence Measures and the Shadows Algorithm

    PubMed Central

    Sakhanenko, Nikita A.

    2015-01-01

    Abstract Information theory is valuable in multiple-variable analysis for being model-free and nonparametric, and for the modest sensitivity to undersampling. We previously introduced a general approach to finding multiple dependencies that provides accurate measures of levels of dependency for subsets of variables in a data set, which is significantly nonzero only if the subset of variables is collectively dependent. This is useful, however, only if we can avoid a combinatorial explosion of calculations for increasing numbers of variables.  The proposed dependence measure for a subset of variables, τ, differential interaction information, Δ(τ), has the property that for subsets of τ some of the factors of Δ(τ) are significantly nonzero, when the full dependence includes more variables. We use this property to suppress the combinatorial explosion by following the “shadows” of multivariable dependency on smaller subsets. Rather than calculating the marginal entropies of all subsets at each degree level, we need to consider only calculations for subsets of variables with appropriate “shadows.” The number of calculations for n variables at a degree level of d grows therefore, at a much smaller rate than the binomial coefficient (n, d), but depends on the parameters of the “shadows” calculation. This approach, avoiding a combinatorial explosion, enables the use of our multivariable measures on very large data sets. We demonstrate this method on simulated data sets, and characterize the effects of noise and sample numbers. In addition, we analyze a data set of a few thousand mutant yeast strains interacting with a few thousand chemical compounds. PMID:26335709

  10. Additive lattice kirigami

    PubMed Central

    Castle, Toen; Sussman, Daniel M.; Tanis, Michael; Kamien, Randall D.

    2016-01-01

    Kirigami uses bending, folding, cutting, and pasting to create complex three-dimensional (3D) structures from a flat sheet. In the case of lattice kirigami, this cutting and rejoining introduces defects into an underlying 2D lattice in the form of points of nonzero Gaussian curvature. A set of simple rules was previously used to generate a wide variety of stepped structures; we now pare back these rules to their minimum. This allows us to describe a set of techniques that unify a wide variety of cut-and-paste actions under the rubric of lattice kirigami, including adding new material and rejoining material across arbitrary cuts in the sheet. We also explore the use of more complex lattices and the different structures that consequently arise. Regardless of the choice of lattice, creating complex structures may require multiple overlapping kirigami cuts, where subsequent cuts are not performed on a locally flat lattice. Our additive kirigami method describes such cuts, providing a simple methodology and a set of techniques to build a huge variety of complex 3D shapes. PMID:27679822

  11. Additive lattice kirigami

    PubMed Central

    Castle, Toen; Sussman, Daniel M.; Tanis, Michael; Kamien, Randall D.

    2016-01-01

    Kirigami uses bending, folding, cutting, and pasting to create complex three-dimensional (3D) structures from a flat sheet. In the case of lattice kirigami, this cutting and rejoining introduces defects into an underlying 2D lattice in the form of points of nonzero Gaussian curvature. A set of simple rules was previously used to generate a wide variety of stepped structures; we now pare back these rules to their minimum. This allows us to describe a set of techniques that unify a wide variety of cut-and-paste actions under the rubric of lattice kirigami, including adding new material and rejoining material across arbitrary cuts in the sheet. We also explore the use of more complex lattices and the different structures that consequently arise. Regardless of the choice of lattice, creating complex structures may require multiple overlapping kirigami cuts, where subsequent cuts are not performed on a locally flat lattice. Our additive kirigami method describes such cuts, providing a simple methodology and a set of techniques to build a huge variety of complex 3D shapes.

  12. Emissions of metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs) from Portland cement manufacturing plants: inter-kiln variability and dependence on fuel-types.

    PubMed

    Zemba, Stephen; Ames, Michael; Green, Laura; Botelho, Maria João; Gossman, David; Linkov, Igor; Palma-Oliveira, José

    2011-09-15

    Emissions from Portland cement manufacturing facilities may increase health risks in nearby populations and are thus subject to stringent regulations. Direct testing of pollutant concentrations in exhaust gases provides the best basis for assessing the extent of these risks. However, these tests (i) are often conducted under stressed, rather than typical, operating conditions, (ii) may be limited in number and duration, and (iii) may be influenced by specific fuel-types and attributes of individual kilns. We report here on the results of more than 150 emissions-tests conducted of two kilns at a Portland cement manufacturing plant in Portugal. The tests measured various regulated metals and polychlorinated dibenzo(p)dioxins and furans (PCDD/Fs). Stack-gas concentrations of pollutants were found to be highly variable, with standard deviations on the order of mean values. Emission rates of many pollutants were higher when coal was used as the main kiln fuel (instead of petroleum coke). Use of various supplemental fuels, however, had little effect on stack emissions, and few statistically significant differences were observed when hazardous waste was included in the fuel mix. Significant differences in emissions for some pollutants were observed between the two kilns despite their similar designs and uses of similar fuels. All measured values were found to be within applicable regulatory limits.

  13. Modelling Solar and Stellar Brightness Variabilities

    NASA Astrophysics Data System (ADS)

    Yeo, K. L.; Shapiro, A. I.; Krivova, N. A.; Solanki, S. K.

    2016-04-01

    Total and spectral solar irradiance, TSI and SSI, have been measured from space since 1978. This is accompanied by the development of models aimed at replicating the observed variability by relating it to solar surface magnetism. Despite significant progress, there remains persisting controversy over the secular change and the wavelength-dependence of the variation with impact on our understanding of the Sun's influence on the Earth's climate. We highlight the recent progress in TSI and SSI modelling with SATIRE. Brightness variations have also been observed for Sun-like stars. Their analysis can profit from knowledge of the solar case and provide additional constraints for solar modelling. We discuss the recent effort to extend SATIRE to Sun-like stars.

  14. Condition-dependent, phenotype-dependent and genetic-dependent factors in the natal dispersal of a solitary rodent.

    PubMed

    Selonen, Vesa; Hanski, Ilpo K

    2010-09-01

    1. Dispersal can be condition- and phenotype-dependent and related to individual genetic differences. Few studies have addressed the relative importance of these factors on dispersal. We studied the factors behind philopatry and dispersal in juvenile Siberian flying squirrels, Pteromys volans L. 2. The dispersal distance and the distances explored before abandoning the natal nest were not related to any of the condition-dependent factors studied such as the area of high-quality habitat or the number of conspecifics near the natal area. In addition, the body mass (a phenotypic trait) of individuals was not related to philopatry and dispersal in flying squirrels. 3. Genetic variability, measured by microsatellite heterozygosity, was positively correlated with dispersal. The correlation was mainly driven by one locus related to the distances explored before abandoning the natal nest. 4. We conclude that condition- and phenotype-dependent factors did not have detectable effects on philopatry and dispersal, but individual heterozygosity was related to dispersal in flying squirrels. Our results suggest that genetic variability is important behind the dispersal of the species. PMID:20561101

  15. [Nicotine dependence].

    PubMed

    Kawazoe, Shingo; Shinkai, Takahiro

    2015-09-01

    Smoking is the most widespread addictive behavior in the world, and it causes physical and psychological dependence on nicotine. As for physical nicotine dependence, nicotine produces rewarding effects by interacting with nicotinic acetylcholine receptors on neurons in the brain's reward system. Psychological dependence on nicotine comes with a complex psychological procedure that is based on distorted cognition which justifies their smoking behavior. Clinicians should support smokers with willingness to quit smoking comprehensively with this knowledge, although the success rate of smoking cessation is no ideal in general. PMID:26394514

  16. Disease in a more variable and unpredictable climate

    NASA Astrophysics Data System (ADS)

    McMahon, T. A.; Raffel, T.; Rohr, J. R.; Halstead, N.; Venesky, M.; Romansic, J.

    2014-12-01

    Global climate change is shifting the dynamics of infectious diseases of humans and wildlife with potential adverse consequences for disease control. Despite this, the role of global climate change in the decline of biodiversity and the emergence of infectious diseases remains controversial. Climate change is expected to increase climate variability in addition to increasing mean temperatures, making climate less predictable. However, few empirical or theoretical studies have considered the effects of climate variability or predictability on disease, despite it being likely that hosts and parasites will have differential responses to climatic shifts. Here we present a theoretical framework for how temperature variation and its predictability influence disease risk by affecting host and parasite acclimation responses. Laboratory experiments and field data on disease-associated frog declines in Latin America support this framework and provide evidence that unpredictable temperature fluctuations, on both monthly and diurnal timescales, decrease frog resistance to the pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd). Furthermore, the pattern of temperature-dependent growth of the fungus on frogs was inconsistent with the pattern of Bd growth in culture, emphasizing the importance of accounting for the host-parasite interaction when predicting climate-dependent disease dynamics. Consistent with our laboratory experiments, increased regional temperature variability associated with global El Niño climatic events was the best predictor of widespread amphibian losses in the genus Atelopus. Thus, incorporating the effects of small-scale temporal variability in climate can greatly improve our ability to predict the effects of climate change on disease.

  17. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing.

    PubMed

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands.

  18. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing

    PubMed Central

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands. PMID:26601037

  19. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing.

    PubMed

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands. PMID:26601037

  20. Lubricating oil compositions containing organometallic additives

    SciTech Connect

    Landry, J.F.; Croudance, M.C.; On, H.P.; Shen, S.Y.

    1987-04-07

    This invention provides novel lubricating oil compositions comprising an organometallic additive, including a metal selected from Groups I, Ib, and VIII of the Periodic System of Elements, e.g. Na, K, Cu, Co, Ni or Fe, chelated with the reaction product of formaldehyde, an amino acid and a phenol, dissolved in a lubricating oil. Depending on the choice of the metal, the above organometallic additive imparts rust inhibition, sludge dispersant, wear reduction and anti-oxidant properties to the lubricating oil compositions.

  1. Classification of the Electrophilic Addition Reactions of Olefins and Acetylenes

    ERIC Educational Resources Information Center

    Wilson, Michael A.

    1975-01-01

    Divides addition reactions into molecular, stepwise, or termolecular, depending on whether the reaction is synchronous or multistep; and further into nucleophilic, electrophilic, or concerted, depending on how the electrons are transferred in the initiation step. (MLH)

  2. Differing Roles of Functional Movement Variability as Experience Increases in Gymnastics.

    PubMed

    Busquets, Albert; Marina, Michel; Davids, Keith; Angulo-Barroso, Rosa

    2016-06-01

    gymnasts). Longswing assessment allowed us to evaluate inter-trial variability in representative performance context.Coordination variability presented two different configurations across experience levels depending on the variable of interest: either a U-shaped or a L- or \\-shaped graph.Increased inter-trial variability of the functional phase events offered flexibility to adapt the longswing performance in the advanced gymnasts, while decreasing variability in arm-trunk coordination modes was critical to improve longswing and to achieve the most advanced level.In addition, the relationship between variability measures and the global performance outcome (i.e. the swing amplitude) revealed different functional roles of movement variability (exploratory or restrictive) as a function of changes in experience levels. PMID:27274664

  3. Differing Roles of Functional Movement Variability as Experience Increases in Gymnastics.

    PubMed

    Busquets, Albert; Marina, Michel; Davids, Keith; Angulo-Barroso, Rosa

    2016-06-01

    gymnasts). Longswing assessment allowed us to evaluate inter-trial variability in representative performance context.Coordination variability presented two different configurations across experience levels depending on the variable of interest: either a U-shaped or a L- or \\-shaped graph.Increased inter-trial variability of the functional phase events offered flexibility to adapt the longswing performance in the advanced gymnasts, while decreasing variability in arm-trunk coordination modes was critical to improve longswing and to achieve the most advanced level.In addition, the relationship between variability measures and the global performance outcome (i.e. the swing amplitude) revealed different functional roles of movement variability (exploratory or restrictive) as a function of changes in experience levels.

  4. Differing Roles of Functional Movement Variability as Experience Increases in Gymnastics

    PubMed Central

    Busquets, Albert; Marina, Michel; Davids, Keith; Angulo-Barroso, Rosa

    2016-01-01

    gymnasts). Longswing assessment allowed us to evaluate inter-trial variability in representative performance context. Coordination variability presented two different configurations across experience levels depending on the variable of interest: either a U-shaped or a L- or \\-shaped graph. Increased inter-trial variability of the functional phase events offered flexibility to adapt the longswing performance in the advanced gymnasts, while decreasing variability in arm-trunk coordination modes was critical to improve longswing and to achieve the most advanced level. In addition, the relationship between variability measures and the global performance outcome (i.e. the swing amplitude) revealed different functional roles of movement variability (exploratory or restrictive) as a function of changes in experience levels. PMID:27274664

  5. Mammalian Target of Rapamycin (mTOR) Tagging Promotes Dendritic Branch Variability through the Capture of Ca2+/Calmodulin-dependent Protein Kinase II α (CaMKIIα) mRNAs by the RNA-binding Protein HuD*

    PubMed Central

    Sosanya, Natasha M.; Cacheaux, Luisa P.; Workman, Emily R.; Niere, Farr; Perrone-Bizzozero, Nora I.; Raab-Graham, Kimberly F.

    2015-01-01

    The fate of a memory, whether stored or forgotten, is determined by the ability of an active or tagged synapse to undergo changes in synaptic efficacy requiring protein synthesis of plasticity-related proteins. A synapse can be tagged, but without the “capture” of plasticity-related proteins, it will not undergo long lasting forms of plasticity (synaptic tagging and capture hypothesis). What the “tag” is and how plasticity-related proteins are captured at tagged synapses are unknown. Ca2+/calmodulin-dependent protein kinase II α (CaMKIIα) is critical in learning and memory and is synthesized locally in neuronal dendrites. The mechanistic (mammalian) target of rapamycin (mTOR) is a protein kinase that increases CaMKIIα protein expression; however, the mechanism and site of dendritic expression are unknown. Herein, we show that mTOR activity mediates the branch-specific expression of CaMKIIα, favoring one secondary, daughter branch over the other in a single neuron. mTOR inhibition decreased the dendritic levels of CaMKIIα protein and mRNA by shortening its poly(A) tail. Overexpression of the RNA-stabilizing protein HuD increased CaMKIIα protein levels and preserved its selective expression in one daughter branch over the other when mTOR was inhibited. Unexpectedly, deleting the third RNA recognition motif of HuD, the domain that binds the poly(A) tail, eliminated the branch-specific expression of CaMKIIα when mTOR was active. These results provide a model for one molecular mechanism that may underlie the synaptic tagging and capture hypothesis where mTOR is the tag, preventing deadenylation of CaMKIIα mRNA, whereas HuD captures and promotes its expression in a branch-specific manner. PMID:25944900

  6. Variable gravity research facility

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Eight fourth-year engineering design students formed two teams to study methods of varying the perceived gravity level in a variable gravity research facility. A tether system and an arm system were the chosen topics. Both teams have produced and built scale models of their design. In addition, a three-credit Special Topics Course (Aviation 370) was formed, as the project offers an excellent opportunity to build a multi-disciplinary program around the initial conceptualization process. Fifty students were registered in the Special Topics course. Each week during a three hour class, a guest lecturer covered one or more of the many areas associated with the concept of a variable-gravity facility. The students formed small groups organized on a multi-disciplinary basis (there were twelve separate disciplines represented by one or more students) where they discussed among themselves the various issues involved. These groups also met outside class for three or more hours each week. During class each group presented oral reports on their findings during a one-hour general question and answer period.

  7. DETECTING VARIABILITY IN MASSIVE ASTRONOMICAL TIME-SERIES DATA. II. VARIABLE CANDIDATES IN THE NORTHERN SKY VARIABILITY SURVEY

    SciTech Connect

    Shin, Min-Su; Yi, Hahn; Kim, Dae-Won; Chang, Seo-Won; Byun, Yong-Ik E-mail: yihahn@galaxy.yonsei.ac.kr E-mail: seowony@galaxy.yonsei.ac.kr

    2012-03-15

    We present variability analysis of data from the Northern Sky Variability Survey (NSVS). Using the clustering method, which defines variable candidates as outliers from large clusters, we cluster 16,189,040 light curves having data points at more than 15 epochs as variable and non-variable candidates in 638 NSVS fields. Variable candidates are selected depending on how strongly they are separated from the largest cluster and how rarely they are grouped together in eight-dimensional space spanned by variability indices. All NSVS light curves are also cross-correlated with IRAS, AKARI, Two Micron All Sky Survey, Sloan Digital Sky Survey (SDSS), and GALEX objects, as well as known objects in the SIMBAD database. The variability analysis and cross-correlation results are provided in a public online database, which can be used to select interesting objects for further investigation. Adopting conservative selection criteria for variable candidates, we find about 1.8 million light curves as possible variable candidates in the NSVS data, corresponding to about 10% of our entire NSVS sample. Multi-wavelength colors help us find specific types of variability among the variable candidates. Moreover, we also use morphological classification from other surveys such as SDSS to suppress spurious cases caused by blending objects or extended sources due to the low angular resolution of the NSVS.

  8. An Efficient Variable-Length Data-Compression Scheme

    NASA Technical Reports Server (NTRS)

    Cheung, Kar-Ming; Kiely, Aaron B.

    1996-01-01

    Adaptive variable-length coding scheme for compression of stream of independent and identically distributed source data involves either Huffman code or alternating run-length Huffman (ARH) code, depending on characteristics of data. Enables efficient compression of output of lossless or lossy precompression process, with speed and simplicity greater than those of older coding schemes developed for same purpose. In addition, scheme suitable for parallel implementation on hardware with modular structure, provides for rapid adaptation to changing data source, compatible with block orientation to alleviate memory requirements, ensures efficiency over wide range of entropy, and easily combined with such other communication schemes as those for containment of errors and for packetization.

  9. Latent Variable Theory

    ERIC Educational Resources Information Center

    Borsboom, Denny

    2008-01-01

    This paper formulates a metatheoretical framework for latent variable modeling. It does so by spelling out the difference between observed and latent variables. This difference is argued to be purely epistemic in nature: We treat a variable as "observed" when the inference from data structure to variable structure can be made with certainty and as…

  10. Wavelength, temperature, and voltage dependent calibration of a nematic liquid crystal multispectral polarization generating device

    SciTech Connect

    Baba, Justin S; Boudreaux, Philip R

    2007-01-01

    Rapid calibration of liquid crystal variable retarder (LCVR) devices is critical for successful clinical implementation of a LC-based Mueller matrix imaging system being developed for noninvasisve skin cancer detection. For multispectral implementation of such a system, the effect of wavelength (), temperature (T), and voltage (V) on the retardance () required to generate each desired polarization state needs to be clearly understood. Calibration involves quantifying this interdependence such that for a given set of system input variables, T, the appropriate voltage is applied across a LC cell to generate a particular retardance. This paper presents findings that elucidate the dependence of voltage, for a set retardance, on the aforementioned variables for a nematic LC cell: 253 mv100 nm-dependence andd 10 mVC T-dependence. Additionally, an empirically derived model is presented that enables initial voltage calibration of retardance for any desired input wavelength within the calibration range of 460-905 nm. copyright 2007 Optical Society of America

  11. Current Climate Variability & Change

    NASA Astrophysics Data System (ADS)

    Diem, J.; Criswell, B.; Elliott, W. C.

    2013-12-01

    Current Climate Variability & Change is the ninth among a suite of ten interconnected, sequential labs that address all 39 climate-literacy concepts in the U.S. Global Change Research Program's Climate Literacy: The Essential Principles of Climate Sciences. The labs are as follows: Solar Radiation & Seasons, Stratospheric Ozone, The Troposphere, The Carbon Cycle, Global Surface Temperature, Glacial-Interglacial Cycles, Temperature Changes over the Past Millennium, Climates & Ecosystems, Current Climate Variability & Change, and Future Climate Change. All are inquiry-based, on-line products designed in a way that enables students to construct their own knowledge of a topic. Questions representative of various levels of Webb's depth of knowledge are embedded in each lab. In addition to the embedded questions, each lab has three or four essential questions related to the driving questions for the lab suite. These essential questions are presented as statements at the beginning of the material to represent the lab objectives, and then are asked at the end as questions to function as a summative assessment. For example, the Current Climate Variability & Change is built around these essential questions: (1) What has happened to the global temperature at the Earth's surface, in the middle troposphere, and in the lower stratosphere over the past several decades?; (2) What is the most likely cause of the changes in global temperature over the past several decades and what evidence is there that this is the cause?; and (3) What have been some of the clearly defined effects of the change in global temperature on the atmosphere and other spheres of the Earth system? An introductory Prezi allows the instructor to assess students' prior knowledge in relation to these questions, while also providing 'hooks' to pique their interest related to the topic. The lab begins by presenting examples of and key differences between climate variability (e.g., Mt. Pinatubo eruption) and

  12. [Complex systems variability analysis using approximate entropy].

    PubMed

    Cuestas, Eduardo

    2010-01-01

    Biological systems are highly complex systems, both spatially and temporally. They are rooted in an interdependent, redundant and pleiotropic interconnected dynamic network. The properties of a system are different from those of their parts, and they depend on the integrity of the whole. The systemic properties vanish when the system breaks down, while the properties of its components are maintained. The disease can be understood as a systemic functional alteration of the human body, which present with a varying severity, stability and durability. Biological systems are characterized by measurable complex rhythms, abnormal rhythms are associated with disease and may be involved in its pathogenesis, they are been termed "dynamic disease." Physicians have long time recognized that alterations of physiological rhythms are associated with disease. Measuring absolute values of clinical parameters yields highly significant, clinically useful information, however evaluating clinical parameters the variability provides additionally useful clinical information. The aim of this review was to study one of the most recent advances in the measurement and characterization of biological variability made possible by the development of mathematical models based on chaos theory and nonlinear dynamics, as approximate entropy, has provided us with greater ability to discern meaningful distinctions between biological signals from clinically distinct groups of patients.

  13. [Complex systems variability analysis using approximate entropy].

    PubMed

    Cuestas, Eduardo

    2010-01-01

    Biological systems are highly complex systems, both spatially and temporally. They are rooted in an interdependent, redundant and pleiotropic interconnected dynamic network. The properties of a system are different from those of their parts, and they depend on the integrity of the whole. The systemic properties vanish when the system breaks down, while the properties of its components are maintained. The disease can be understood as a systemic functional alteration of the human body, which present with a varying severity, stability and durability. Biological systems are characterized by measurable complex rhythms, abnormal rhythms are associated with disease and may be involved in its pathogenesis, they are been termed "dynamic disease." Physicians have long time recognized that alterations of physiological rhythms are associated with disease. Measuring absolute values of clinical parameters yields highly significant, clinically useful information, however evaluating clinical parameters the variability provides additionally useful clinical information. The aim of this review was to study one of the most recent advances in the measurement and characterization of biological variability made possible by the development of mathematical models based on chaos theory and nonlinear dynamics, as approximate entropy, has provided us with greater ability to discern meaningful distinctions between biological signals from clinically distinct groups of patients. PMID:21450141

  14. Adam Smith and dependency.

    PubMed

    Ozler, Sule

    2012-06-01

    The focus of this paper is the works and life of Adam Smith, who is widely recognized as the father and founder of contemporary economics. Latent content analysis is applied to his seminal text in economics, An Inquiry into the Nature and Causes of the Wealth of Nations (1776). The results reveal that Smith considers dependence on others a problem and sees the solution to this problem in impersonalized interdependence. In addition, his views on social dependency and personal dependency, reflected in his Lectures on Jurisprudence (1963) and The Theory of Moral Sentiments (1759), are analyzed. This analysis suggests a central tension between dependence and independence in Smith's writings. The personal dependency patterns he exhibited in his life, which also suggest a tension between dependence and independence, are identified through a reading of his biographies. Based on insights from psychoanalytic literature, this paper proposes that developing the ideas in the Wealth of Nations was part of Smith's creative solution to this tension. In particular, his solution to one individual's dependence on another was through a system of impersonalized interdependence. In other words, Smith defended against his personal dependence through his economic theorizing. PMID:22712591

  15. Adam Smith and dependency.

    PubMed

    Ozler, Sule

    2012-06-01

    The focus of this paper is the works and life of Adam Smith, who is widely recognized as the father and founder of contemporary economics. Latent content analysis is applied to his seminal text in economics, An Inquiry into the Nature and Causes of the Wealth of Nations (1776). The results reveal that Smith considers dependence on others a problem and sees the solution to this problem in impersonalized interdependence. In addition, his views on social dependency and personal dependency, reflected in his Lectures on Jurisprudence (1963) and The Theory of Moral Sentiments (1759), are analyzed. This analysis suggests a central tension between dependence and independence in Smith's writings. The personal dependency patterns he exhibited in his life, which also suggest a tension between dependence and independence, are identified through a reading of his biographies. Based on insights from psychoanalytic literature, this paper proposes that developing the ideas in the Wealth of Nations was part of Smith's creative solution to this tension. In particular, his solution to one individual's dependence on another was through a system of impersonalized interdependence. In other words, Smith defended against his personal dependence through his economic theorizing.

  16. Additives in fibers and fabrics.

    PubMed

    Barker, R H

    1975-06-01

    The additives and contaminants which occur in textile fibers vary widely, depending on the type of fiber and the pretreatment which it has received. Synthetic fibers such as nylon and polyester contain trace amounts of contaminants such as catalysts and catalyst deactivators which remain after the synthesis of the basic polymers. In addition, there are frequently a number of materials which are added to perform specific functions in almost all man-made fibers. Examples of these would include traces of metals or metal salts used as tracers for identification of specific lots of fiber, TiO2 or similar materials added as delustrants, and a host of organic species added for such special purposes as antistatic agents or flame retardants. There may also be considerable quantities of residual monomer or small oligomers dissolved in the polymer matrix. The situation becomes even more complex after the fibers are converted into fabric form. Numerous materials are applied at various stages of fabric preparation to act as lubricants, sizing agents, antistats, bleaches, and wetting agents to facilitate the processing, but these are normally removed before the fabric reaches the cutters of the ultimate consumers and therefore usually do not constitute potential hazards. However, there are many other chemical agents which are frequently added during the later stages of fabric preparation and which are not designed to be removed. Aside from dyes and printing pigments, the most common additive for apparel fabrics is a durable press treatment. This generally involves the use of materials capable of crosslinking cellulosics by reacting through such functions as N-methylolated amides or related compounds such as ureas and carbamates. These materials pose some potential hazards due to both the nitrogenous bases and the formaldehyde which they usually release. There is usually also some residual catalyst in fabrics which have received such treatments. Other types of chemical treatments

  17. Additives in fibers and fabrics.

    PubMed Central

    Barker, R H

    1975-01-01

    The additives and contaminants which occur in textile fibers vary widely, depending on the type of fiber and the pretreatment which it has received. Synthetic fibers such as nylon and polyester contain trace amounts of contaminants such as catalysts and catalyst deactivators which remain after the synthesis of the basic polymers. In addition, there are frequently a number of materials which are added to perform specific functions in almost all man-made fibers. Examples of these would include traces of metals or metal salts used as tracers for identification of specific lots of fiber, TiO2 or similar materials added as delustrants, and a host of organic species added for such special purposes as antistatic agents or flame retardants. There may also be considerable quantities of residual monomer or small oligomers dissolved in the polymer matrix. The situation becomes even more complex after the fibers are converted into fabric form. Numerous materials are applied at various stages of fabric preparation to act as lubricants, sizing agents, antistats, bleaches, and wetting agents to facilitate the processing, but these are normally removed before the fabric reaches the cutters of the ultimate consumers and therefore usually do not constitute potential hazards. However, there are many other chemical agents which are frequently added during the later stages of fabric preparation and which are not designed to be removed. Aside from dyes and printing pigments, the most common additive for apparel fabrics is a durable press treatment. This generally involves the use of materials capable of crosslinking cellulosics by reacting through such functions as N-methylolated amides or related compounds such as ureas and carbamates. These materials pose some potential hazards due to both the nitrogenous bases and the formaldehyde which they usually release. There is usually also some residual catalyst in fabrics which have received such treatments. Other types of chemical treatments

  18. Variable conductance heat pipe technology

    NASA Technical Reports Server (NTRS)

    Marcus, B. D.; Edwards, D. K.; Anderson, W. T.

    1973-01-01

    Research and development programs in variable conductance heat pipe technology were conducted. The treatment has been comprehensive, involving theoretical and/or experimental studies in hydrostatics, hydrodynamics, heat transfer into and out of the pipe, fluid selection, and materials compatibility, in addition to the principal subject of variable conductance control techniques. Efforts were not limited to analytical work and laboratory experimentation, but extended to the development, fabrication and test of spacecraft hardware, culminating in the successful flight of the Ames Heat Pipe Experiment on the OAO-C spacecraft.

  19. Motor coordination of articulators depends on the place of articulation.

    PubMed

    Inoue-Arai, Maristela Sayuri; Ono, Takashi; Honda, Ei-ichi; Kurabayashi, Tohru; Moriyama, Keiji

    2009-05-16

    Although the sounds/p/and/k/are both voiceless plosives, they have different places of articulation: bilabial and velar, respectively. The purpose of this study was to determine the relationship among articulators in plosives with reference to their place of articulation. Ten healthy subjects repeated bilabial and velar plosives in synchronization with magnetic resonance scanning. Each run was measured using a gradient echo sequence. Several linear and angular variables were defined to delineate the individual movements of articulators and to determine the temporal relationships among articulators. These variables showed distinctive changes depending on the place of articulation. In addition, movement of the velum was significantly correlated with that of the lips and the anterior part of the tongue in the bilabial plosive and with the posterior part of the tongue in the velar plosive. We conclude that unitary motor coordination of articulators depends on the place of articulation. PMID:19126418

  20. Sustainability Characterization for Additive Manufacturing

    PubMed Central

    Mani, Mahesh; Lyons, Kevin W; Gupta, SK

    2014-01-01

    Additive manufacturing (AM) has the potential to create geometrically complex parts that require a high degree of customization, using less material and producing less waste. Recent studies have shown that AM can be an economically viable option for use by the industry, yet there are some inherent challenges associated with AM for wider acceptance. The lack of standards in AM impedes its use for parts production since industries primarily depend on established standards in processes and material selection to ensure the consistency and quality. Inability to compare AM performance against traditional manufacturing methods can be a barrier for implementing AM processes. AM process sustainability has become a driver due to growing environmental concerns for manufacturing. This has reinforced the importance to understand and characterize AM processes for sustainability. Process characterization for sustainability will help close the gaps for comparing AM performance to traditional manufacturing methods. Based on a literature review, this paper first examines the potential environmental impacts of AM. A methodology for sustainability characterization of AM is then proposed to serve as a resource for the community to benchmark AM processes for sustainability. Next, research perspectives are discussed along with relevant standardization efforts. PMID:26601038

  1. Sustainability Characterization for Additive Manufacturing.

    PubMed

    Mani, Mahesh; Lyons, Kevin W; Gupta, S K

    2014-01-01

    Additive manufacturing (AM) has the potential to create geometrically complex parts that require a high degree of customization, using less material and producing less waste. Recent studies have shown that AM can be an economically viable option for use by the industry, yet there are some inherent challenges associated with AM for wider acceptance. The lack of standards in AM impedes its use for parts production since industries primarily depend on established standards in processes and material selection to ensure the consistency and quality. Inability to compare AM performance against traditional manufacturing methods can be a barrier for implementing AM processes. AM process sustainability has become a driver due to growing environmental concerns for manufacturing. This has reinforced the importance to understand and characterize AM processes for sustainability. Process characterization for sustainability will help close the gaps for comparing AM performance to traditional manufacturing methods. Based on a literature review, this paper first examines the potential environmental impacts of AM. A methodology for sustainability characterization of AM is then proposed to serve as a resource for the community to benchmark AM processes for sustainability. Next, research perspectives are discussed along with relevant standardization efforts.

  2. Variable immune molecules in invertebrates.

    PubMed

    Cerenius, Lage; Söderhäll, Kenneth

    2013-12-01

    Recently it has become evident that invertebrates may mount a highly variable immune response that is dependent on which pathogen is involved. The molecular mechanisms behind this diversity are beginning to be unravelled and in several invertebrate taxa immune proteins exhibiting a broad range of diversity have been found. In some cases, evidence has been gathered suggesting that this molecular diversity translates into the ability of an affected invertebrate to mount a defence that is specifically aimed at a particular pathogen.

  3. Measurement of Tanning Dependence

    PubMed Central

    Heckman, C.J.; Darlow, S.; Kloss, J.D.; Cohen-Filipic, J.; Manne, S.L.; Munshi, T.; Yaroch, A.L.; Perlis, C.

    2014-01-01

    Background Indoor tanning has been found to be addictive. However, the most commonly-used tanning dependence measures have not been well-validated. Objective The study’s purpose was to explore the psychometric characteristics of and compare the mCAGE (modified Cut-down, Annoyed, Guilty, Eye-opener Scale), mDSM-IV-TR (modified Diagnostic and Statistical Manual of Mental Disorders – Fourth Edition - Text Revised), and TAPS (Tanning Pathology Scale) measures of tanning dependence and provide recommendations for research and practice. Methods This study was a cross-sectional online survey with 18–25 year old female university students. The main outcome variable was tanning dependence measured by the mCAGE, mDSM-IV-TR, and TAPS. Results Internal consistency of the TAPS subscales was good but was poor for the mCAGE and mDSM-IV-TR, except when their items were combined. Agreement between the mCAGE and mDSM-IV-TR was fair. Factor analysis of the TAPS confirmed the current four-factor structure. All of the tanning dependence scales were significantly correlated with one another. Likewise, most of the tanning dependence scales were significantly correlated with other measures of tanning attitudes and behaviors. However, the tolerance to tanning TAPS subscale was not significantly correlated with any measure of tanning attitudes or behaviors and had the lowest subscale internal reliability and eigenvalues. Conclusion Based on the data and existing literature, we make recommendations for the continued use of tanning dependence measures. Intervention may be needed for the approximately 5% of college women who tend to be classified as tanning dependent across measures. Monitoring of individuals reporting tanning dependence symptoms is warranted. PMID:23980870

  4. Barn Owl Productivity Response to Variability of Vole Populations.

    PubMed

    Pavluvčík, Petr; Poprach, Karel; Machar, Ivo; Losík, Jan; Gouveia, Ana; Tkadlec, Emil

    2015-01-01

    We studied the response of the barn owl annual productivity to the common vole population numbers and variability to test the effects of environmental stochasticity on their life histories. Current theory predicts that temporal environmental variability can affect long-term nonlinear responses (e.g., production of young) both positively and negatively, depending on the shape of the relationship between the response and environmental variables. At the level of the Czech Republic, we examined the shape of the relationship between the annual sum of fledglings (annual productivity) and vole numbers in both non-detrended and detrended data. At the districts' level, we explored whether the degree of synchrony (measured by the correlation coefficient) and the strength of the productivity response increase (measured by the regression coefficient) in areas with higher vole population variability measured by the s-index. We found that the owls' annual productivity increased linearly with vole numbers in the Czech Republic. Furthermore, based on district data, we also found that synchrony between dynamics in owls' reproductive output and vole numbers increased with vole population variability. However, the strength of the response was not affected by the vole population variability. Additionally, we have shown that detrending remarkably increases the Taylor's exponent b relating variance to mean in vole time series, thereby reversing the relationship between the coefficient of variation and the mean. This shift was not responsible for the increased synchrony with vole population variability. Instead, we suggest that higher synchrony could result from high food specialization of owls on the common vole in areas with highly fluctuating vole populations.

  5. Barn Owl Productivity Response to Variability of Vole Populations

    PubMed Central

    Pavluvčík, Petr; Poprach, Karel; Machar, Ivo; Losík, Jan; Gouveia, Ana; Tkadlec, Emil

    2015-01-01

    We studied the response of the barn owl annual productivity to the common vole population numbers and variability to test the effects of environmental stochasticity on their life histories. Current theory predicts that temporal environmental variability can affect long-term nonlinear responses (e.g., production of young) both positively and negatively, depending on the shape of the relationship between the response and environmental variables. At the level of the Czech Republic, we examined the shape of the relationship between the annual sum of fledglings (annual productivity) and vole numbers in both non-detrended and detrended data. At the districts’ level, we explored whether the degree of synchrony (measured by the correlation coefficient) and the strength of the productivity response increase (measured by the regression coefficient) in areas with higher vole population variability measured by the s-index. We found that the owls’ annual productivity increased linearly with vole numbers in the Czech Republic. Furthermore, based on district data, we also found that synchrony between dynamics in owls’ reproductive output and vole numbers increased with vole population variability. However, the strength of the response was not affected by the vole population variability. Additionally, we have shown that detrending remarkably increases the Taylor’s exponent b relating variance to mean in vole time series, thereby reversing the relationship between the coefficient of variation and the mean. This shift was not responsible for the increased synchrony with vole population variability. Instead, we suggest that higher synchrony could result from high food specialization of owls on the common vole in areas with highly fluctuating vole populations. PMID:26709518

  6. The influence of climate variables on dengue in Singapore.

    PubMed

    Pinto, Edna; Coelho, Micheline; Oliver, Leuda; Massad, Eduardo

    2011-12-01

    In this work we correlated dengue cases with climatic variables for the city of Singapore. This was done through a Poisson Regression Model (PRM) that considers dengue cases as the dependent variable and the climatic variables (rainfall, maximum and minimum temperature and relative humidity) as independent variables. We also used Principal Components Analysis (PCA) to choose the variables that influence in the increase of the number of dengue cases in Singapore, where PC₁ (Principal component 1) is represented by temperature and rainfall and PC₂ (Principal component 2) is represented by relative humidity. We calculated the probability of occurrence of new cases of dengue and the relative risk of occurrence of dengue cases influenced by climatic variable. The months from July to September showed the highest probabilities of the occurrence of new cases of the disease throughout the year. This was based on an analysis of time series of maximum and minimum temperature. An interesting result was that for every 2-10°C of variation of the maximum temperature, there was an average increase of 22.2-184.6% in the number of dengue cases. For the minimum temperature, we observed that for the same variation, there was an average increase of 26.1-230.3% in the number of the dengue cases from April to August. The precipitation and the relative humidity, after analysis of correlation, were discarded in the use of Poisson Regression Model because they did not present good correlation with the dengue cases. Additionally, the relative risk of the occurrence of the cases of the disease under the influence of the variation of temperature was from 1.2-2.8 for maximum temperature and increased from 1.3-3.3 for minimum temperature. Therefore, the variable temperature (maximum and minimum) was the best predictor for the increased number of dengue cases in Singapore.

  7. Barn Owl Productivity Response to Variability of Vole Populations.

    PubMed

    Pavluvčík, Petr; Poprach, Karel; Machar, Ivo; Losík, Jan; Gouveia, Ana; Tkadlec, Emil

    2015-01-01

    We studied the response of the barn owl annual productivity to the common vole population numbers and variability to test the effects of environmental stochasticity on their life histories. Current theory predicts that temporal environmental variability can affect long-term nonlinear responses (e.g., production of young) both positively and negatively, depending on the shape of the relationship between the response and environmental variables. At the level of the Czech Republic, we examined the shape of the relationship between the annual sum of fledglings (annual productivity) and vole numbers in both non-detrended and detrended data. At the districts' level, we explored whether the degree of synchrony (measured by the correlation coefficient) and the strength of the productivity response increase (measured by the regression coefficient) in areas with higher vole population variability measured by the s-index. We found that the owls' annual productivity increased linearly with vole numbers in the Czech Republic. Furthermore, based on district data, we also found that synchrony between dynamics in owls' reproductive output and vole numbers increased with vole population variability. However, the strength of the response was not affected by the vole population variability. Additionally, we have shown that detrending remarkably increases the Taylor's exponent b relating variance to mean in vole time series, thereby reversing the relationship between the coefficient of variation and the mean. This shift was not responsible for the increased synchrony with vole population variability. Instead, we suggest that higher synchrony could result from high food specialization of owls on the common vole in areas with highly fluctuating vole populations. PMID:26709518

  8. Effect of Operating Parameters and Chemical Additives on Crystal Habit and Specific Cake Resistance of Zinc Hydroxide Precipitates

    SciTech Connect

    Alwin, Jennifer Louise

    1999-08-01

    The effect of process parameters and chemical additives on the specific cake resistance of zinc hydroxide precipitates was investigated. The ability of a slurry to be filtered is dependent upon the particle habit of the solid and the particle habit is influenced by certain process variables. The process variables studied include neutralization temperature, agitation type, and alkalinity source used for neutralization. Several commercially available chemical additives advertised to aid in solid/liquid separation were also examined in conjunction with hydroxide precipitation. A statistical analysis revealed that the neutralization temperature and the source of alkalinity were statistically significant in influencing the specific cake resistance of zinc hydroxide precipitates in this study. The type of agitation did not significantly effect the specific cake resistance of zinc hydroxide precipitates. The use of chemical additives in conjunction with hydroxide precipitation had a favorable effect on the filterability. The morphology of the hydroxide precipitates was analyzed using scanning electron microscopy.

  9. Rainfall variability effects on aggregate crop model predictions

    NASA Astrophysics Data System (ADS)

    Dzotsi, Kofikuma Adzewoda

    Crop production operates in a highly heterogeneous environment. Space-time variability in weather and spatial heterogeneity in soil and management generate variability in crop yield. While it is practically unfeasible to thoroughly sample the variability of the crop environment, quantification of the associated uncertainties in crop performance can provide vital information for decision-making. The present study used rainfall data collected in southwestern Georgia at scales ranging from 1 km to 60 km to assess the effect of weather variability (in particular rainfall) on crop predictions aggregated over soil and management variations. The simple SALUS (System Approach to Land Use Sustainability) crop model was integrated in DSSAT (Decision Support System for Agrotechnology Transfer) then parameterized and tested for maize, peanut and cotton for use in obtaining the crop predictions. Analysis of the rainfall data indicated that variability in storm characteristics depends upon the season. Winter rainfall was more correlated at a mean distance of 54 km between locations than summer rainfall was at a mean distance of 3 km. The pairwise correlation between locations decreased with distance faster in the summer than in the winter. This rainfall variability translated into crop yield variability in the study area (about 3100 km²). It was found that weather variability explained 60% and 49% of maize yield variability respectively in 2010 and 2011 when heterogeneity in weather, soil, cultivar and planting dates were accounted for simultaneously. Uncertainties in crop predictions due to rainfall spatial uncertainty decreased as the number of sites where weather data were collected increased. Expressed in terms of maize yield coefficient of variation, this uncertainty decreased exponentially from 27% to approximately 4% at a sampling density of 20 weather locations. Based on 30 years of generated weather data, it was concluded that the general form of the relationship

  10. Anaerobic sludge digestion with a biocatalytic additive

    SciTech Connect

    Ghosh, S.; Henry, M.P.; Fedde, P.A.

    1982-01-01

    The objective of this research was to evaluate the effects of a lactobacillus additive an anaerobic sludge digestion under normal, variable, and overload operating conditions. The additive was a whey fermentation product of an acid-tolerant strain of Lactobacillus acidophilus fortified with CaCO/sub 3/, (NH/sub 4/)/sub 2/HPO/sub 4/, ferrous lactate, and lactic acid. The lactobacillus additive is multifunctional in nature and provides growth factors, metabolic intermediates, and enzymes needed for substrate degradation and cellular synthesis. The experimental work consisted of several pairs of parallel mesophilic (35/sup 0/C) digestion runs (control and test) conducted in five experimental phases. Baseline runs without the additive showed that the two experimental digesters had the same methane content, gas production rate (GPR), and ethane yield. The effect of the additive was to increase methane yield and GPR by about 5% (which was statistically significant) during digester operation at a loading rate (LR) of 3.2 kg VS/m/sup 3/-day and a hydraulic retention time (HRT) of 14 days. Data collected from the various experimental phases showed that the biochemical additive increased methane yield, gas production rate, and VS reduction, and decreased volatile acids accumulation. In addition, it enhanced digester buffer capacity and improved the fertilizer value and dewatering characteristics of the digested residue.

  11. Environmental Variables as Predictors of Academic Performance.

    ERIC Educational Resources Information Center

    Henderson, Ronald W.

    This project used six environmental variables identified by Dave (1963) and Wolf (1964) and three additional variables (identification with models, range of social interaction, and perception of practical value of education) to predict academic achievement in six-year-old Mexican-American children from an economically depressed area. The children…

  12. The SU(2) action-angle variables

    NASA Technical Reports Server (NTRS)

    Ellinas, Demosthenes

    1993-01-01

    Operator angle-action variables are studied in the frame of the SU(2) algebra, and their eigenstates and coherent states are discussed. The quantum mechanical addition of action-angle variables is shown to lead to a noncommutative Hopf algebra. The group contraction is used to make the connection with the harmonic oscillator.

  13. Variables related to romanticism and self-esteem in pregnant teenagers.

    PubMed

    Medora, N P; Goldstein, A; von der Hellen, C

    1993-01-01

    In this study, the Dean Romanticism Scale and the Bachman Self-esteem Scale were administered to 121 teenagers between the ages of 12 and 19 in Southern California to investigate their degree of romanticism and self-esteem. The study also explored whether there was any relationship between the dependent variables of romanticism and self-esteem and ten independent variables--age, race, place of residence during pregnancy, age when first sexual intercourse occurred, age when pregnancy occurred, incidence of sexual abuse, incidence of abortion, adoption considerations, whether the subject was currently sexually active, and whether the teenager planned to have a child with the father of the baby. The results indicated that two variables were significantly related to feelings of romanticism--adoption considerations and whether the adolescent planned to have a child with the baby's father. In addition, two variables were significantly related to self-esteem--the incidence of sexual abuse and the incidence of abortion. PMID:8456604

  14. A study of engine variable geometry systems for an advanced high subsonic long range commercial aircraft

    NASA Technical Reports Server (NTRS)

    Compagnon, M. A.

    1973-01-01

    Several variable geometry high Mach inlet concepts, aimed at meeting a system noise objective of 15 EPNdB below FAR part 36, for a long range, Mach 0.9 advanced commercial transport are assessed and compared to a fixed geometry inlet with multiple splitters. The effects of a variable exhaust nozzle (mixed exhaust engine) on noise, inlet geometry requirements, and economics are also presented. The best variable geometry inlet configuration identified is a variable cowl design which relies on a high throat Mach number for additional inlet noise suppression only at takeoff, and depends entirely on inlet wall treatment for noise suppression at approach power. Relative economic penalties as a function of noise level are also presented.

  15. Electrophysiological variability in the SH-SY5Y cellular line.

    PubMed

    Santillo, Silvia; Schiano Moriello, Aniello; Di Maio, Vito

    2014-01-01

    The basic electrophysiological properties of SH-SY5Y tumour cells have been studied by whole cell patch-clamp in voltage clamp configuration. The results shown the existence of a large variability of the response among individual cells in the same experimental conditions. Experiments conducted by using different ionic concentrations of the recording pipette filling solution, yielded a significant variability of peak current amplitude for all the filling solutions used. In addition, variability among groups was detected. The inter-group variability was not dependent on the different ionic components among the groups. Our results confirm earlier findings that this cell line is not constituted of an uniform population of cells. Moreover, from the present results we can conclude that these cells have diverse regulatory patterns of membrane conductance, probably due to both the expression as well as a non precise regulation of the membrane density of the different channels. PMID:24448369

  16. Foundational Forces & Hidden Variables in Technology Commercialization

    NASA Astrophysics Data System (ADS)

    Barnett, Brandon

    2011-03-01

    The science of physics seems vastly different from the process of technology commercialization. Physics strives to understand our world through the experimental deduction of immutable laws and dependent variables and the resulting macro-scale phenomenon. In comparison, the~goal of business is to make a profit by addressing the needs, preferences, and whims of individuals in a market. It may seem that this environment is too dynamic to identify all the hidden variables and deduct the foundational forces that impact a business's ability to commercialize innovative technologies. One example of a business ``force'' is found in the semiconductor industry. In 1965, Intel co-founder Gordon Moore predicted that the number of transistors incorporated in a chip will approximately double every 24 months. Known as Moore's Law, this prediction has become the guiding principle for the semiconductor industry for the last 40 years. Of course, Moore's Law is not really a law of nature; rather it is the result of efforts by Intel and the entire semiconductor industry. A closer examination suggests that there are foundational principles of business that underlie the macro-scale phenomenon of Moore's Law. Principles of profitability, incentive, and strategic alignment have resulted in a coordinated influx of resources that has driven technologies to market, increasing the profitability of the semiconductor industry and optimizing the fitness of its participants. New innovations in technology are subject to these same principles. So, in addition to traditional market forces, these often unrecognized forces and variables create challenges for new technology commercialization. In this talk, I will draw from ethnographic research, complex adaptive theory, and industry data to suggest a framework with which to think about new technology commercialization. Intel's bio-silicon initiative provides a case study.

  17. Latent variable models with nonparametric interaction effects of latent variables.

    PubMed

    Song, Xinyuan; Lu, Zhaohua; Feng, Xiangnan

    2014-05-10

    Renal disease is one of the common complications of diabetes, especially for Asian populations. Moreover, cardiovascular and renal diseases share common risk factors. This paper proposes a latent variable model with nonparametric interaction effects of latent variables for a study based on the Hong Kong Diabetes Registry, which was established in 1995 as part of a continuous quality improvement program at the Prince of Wales Hospital in Hong Kong. Renal outcome (outcome latent variable) is regressed in terms of cardiac function and diabetes (explanatory latent variables) through an additive structural equation formulated using a series of unspecified univariate and bivariate smooth functions. The Bayesian P-splines approach, along with a Markov chain Monte Carlo algorithm, is proposed to estimate smooth functions, unknown parameters, and latent variables in the model. The performance of the developed methodology is demonstrated via a simulation study. The effect of the nonparametric interaction of cardiac function and diabetes on renal outcome is investigated using the proposed methodology. PMID:24338916

  18. Interpersonal dependency in alcoholic and obese men.

    PubMed

    Mills, J K

    1995-06-01

    While psychological conflict about dependency needs of alcoholic and obese persons has been widely observed, few studies have examined differences in dependency characteristics between these clinical groups. The Interpersonal Dependency Inventory was administered to 22 alcoholic and 8 morbidly obese men in intensive treatment for alcohol and obesity. The original hypothesis that alcoholic and obese men would show similar dependency needs was supported. Dependency correlates of personality may serve as useful predictor variables in the clinical treatment of alcoholic and obese persons.

  19. Variables associated with upper extremity function in patients with Duchenne muscular dystrophy.

    PubMed

    Janssen, Mariska M H P; Hendriks, Jan C M; Geurts, Alexander C H; de Groot, Imelda J M

    2016-09-01

    Preserving upper extremity (UE) function in patients with Duchenne muscular dystrophy (DMD) is extremely important as it is related to independence and quality of life. For clinical decision making, knowledge of variables associated with UE function is necessary. This knowledge is, however, limited. Therefore, this study aims to gain more insight into the variables associated with UE function in DMD. Data from an international web-based questionnaire on UE function, obtained from 213 DMD patients, were used. Six dependent variables regarding UE function were used in multivariable linear regression analyses. In addition, 26 independent variables regarding patient characteristics, medication, therapy, supportive aids, pain, stiffness and participation were used. Twelve independent variables showed a significant relation to UE function. Variables with a negative relation to UE function were: later disease stage, occurrence of scoliosis, higher age, use of UE splints, more frequent stiffness complaints, more limitations due to stiffness, more frequent elbow pain, and having physical therapy. A positive relation with UE function was seen for going to school or work, use of corticosteroids, higher BMI, and higher age at diagnosis. These variables explained 56-81 % of the variation of the different measures of UE function. Knowledge of variables associated with UE function is very important in the clinical management of DMD patients. The results of this study suggest that corticosteroid use and participation in school and work related activities are positively related to UE function in DMD patients, as well as reducing pain and stiffness and preventing scoliosis.

  20. Variables associated with upper extremity function in patients with Duchenne muscular dystrophy.

    PubMed

    Janssen, Mariska M H P; Hendriks, Jan C M; Geurts, Alexander C H; de Groot, Imelda J M

    2016-09-01

    Preserving upper extremity (UE) function in patients with Duchenne muscular dystrophy (DMD) is extremely important as it is related to independence and quality of life. For clinical decision making, knowledge of variables associated with UE function is necessary. This knowledge is, however, limited. Therefore, this study aims to gain more insight into the variables associated with UE function in DMD. Data from an international web-based questionnaire on UE function, obtained from 213 DMD patients, were used. Six dependent variables regarding UE function were used in multivariable linear regression analyses. In addition, 26 independent variables regarding patient characteristics, medication, therapy, supportive aids, pain, stiffness and participation were used. Twelve independent variables showed a significant relation to UE function. Variables with a negative relation to UE function were: later disease stage, occurrence of scoliosis, higher age, use of UE splints, more frequent stiffness complaints, more limitations due to stiffness, more frequent elbow pain, and having physical therapy. A positive relation with UE function was seen for going to school or work, use of corticosteroids, higher BMI, and higher age at diagnosis. These variables explained 56-81 % of the variation of the different measures of UE function. Knowledge of variables associated with UE function is very important in the clinical management of DMD patients. The results of this study suggest that corticosteroid use and participation in school and work related activities are positively related to UE function in DMD patients, as well as reducing pain and stiffness and preventing scoliosis. PMID:27314968

  1. On the Variability of the Dmanisi Mandibles

    PubMed Central

    Bermúdez de Castro, José María; Martinón-Torres, María; Sier, Mark Jan; Martín-Francés, Laura

    2014-01-01

    The description of a new skull (D4500) from the Dmanisi site (Republic of Georgia) has reopened the debate about the morphological variability within the genus Homo. The new skull fits with a mandible (D2600) often referred as ‘big’ or ‘enigmatic’ because of its differences with the other Dmanisi mandibles (D211 and D2735). In this report we present a comparative study of the variability of the Dmanisi mandibles under a different perspective, as we focus in morphological aspects related to growth and development. We have followed the notion of modularity and phenotypic integration in order to understand the architectural differences observed within the sample. Our study reveals remarkable shape differences between D2600 and the other two mandibles, that are established early in the ontogeny (during childhood or even before) and that do not depend on size or sexual dimorphism. In addition, D2600 exhibits a mosaic of primitive and derived features regarding the Homo clade, which is absent in D211 and D2735. This mosaic expression is related to the location of the features and can be explained under the concept of modularity. Our study would support the possibility of two different paleodemes represented at the Dmanisi site. This hypothesis has been previously rejected on the basis that all the individuals were constrained in the same stratigraphic and taphonomic settings. However, our revision of the complex Dmanisi stratigraphy suggests that the accumulation could cover an undetermined period of time. Even if “short” in geological terms, the hominin accumulation was not necessarily synchronic. In the same line we discard that the differences between D2600 and the small mandibles are consequence of wear-related dentoalveolar remodeling. In addition, dental wear pattern of D2600 could suggest an adaptation to a different ecological niche than the other Dmanisi individuals. PMID:24586309

  2. Inside of the Linear Relation between Dependent and Independent Variables

    PubMed Central

    Jäntschi, Lorentz; Pruteanu, Lavinia L.; Cozma, Alina C.; Bolboacă, Sorana D.

    2015-01-01

    Simple and multiple linear regression analyses are statistical methods used to investigate the link between activity/property of active compounds and the structural chemical features. One assumption of the linear regression is that the errors follow a normal distribution. This paper introduced a new approach to solving the simple linear regression in which no assumptions about the distribution of the errors are made. The proposed approach maximizes the probability of observing the event according to the random error. The use of the proposed approach is illustrated in ten classes of compounds with different activities or properties. The proposed method proved reliable and was showed to fit properly the observed data compared to the convenient approach of normal distribution of the errors. PMID:26101543

  3. Inside of the Linear Relation between Dependent and Independent Variables.

    PubMed

    Jäntschi, Lorentz; Pruteanu, Lavinia L; Cozma, Alina C; Bolboacă, Sorana D

    2015-01-01

    Simple and multiple linear regression analyses are statistical methods used to investigate the link between activity/property of active compounds and the structural chemical features. One assumption of the linear regression is that the errors follow a normal distribution. This paper introduced a new approach to solving the simple linear regression in which no assumptions about the distribution of the errors are made. The proposed approach maximizes the probability of observing the event according to the random error. The use of the proposed approach is illustrated in ten classes of compounds with different activities or properties. The proposed method proved reliable and was showed to fit properly the observed data compared to the convenient approach of normal distribution of the errors.

  4. Variability as an Operant?

    ERIC Educational Resources Information Center

    Holth, Per

    2012-01-01

    A series of experiments on operant variability by Neuringer and colleagues (e.g., Neuringer, 1986, 2002; Page & Neuringer, 1985) have been repeatedly cited as showing that behavioral variability can be reinforced by making reinforcement contingent on it. They showed that the degree of variability in pigeons' eight-peck sequences, as measured by U…

  5. Variable volume maser techniques

    NASA Technical Reports Server (NTRS)

    Reinhardt, V. S.

    1977-01-01

    The frequency stability of hydrogen masers in variable volume storage bulbs is discussed in terms of wall shift. Variable volume devices discussed include: Brenner flexible bulb, Debely device, and the concertina hydrogen maser. A flexible cone variable volume element outside the cavity is described.

  6. Variable-amplitude oscillatory shear response of amorphous materials

    NASA Astrophysics Data System (ADS)

    Perchikov, Nathan; Bouchbinder, Eran

    2014-06-01

    Variable-amplitude oscillatory shear tests are emerging as powerful tools to investigate and quantify the nonlinear rheology of amorphous solids, complex fluids, and biological materials. Quite a few recent experimental and atomistic simulation studies demonstrated that at low shear amplitudes, an amorphous solid settles into an amplitude- and initial-conditions-dependent dissipative limit cycle, in which back-and-forth localized particle rearrangements periodically bring the system to the same state. At sufficiently large shear amplitudes, the amorphous system loses memory of the initial conditions, exhibits chaotic particle motions accompanied by diffusive behavior, and settles into a stochastic steady state. The two regimes are separated by a transition amplitude, possibly characterized by some critical-like features. Here we argue that these observations support some of the physical assumptions embodied in the nonequilibrium thermodynamic, internal-variables based, shear-transformation-zone model of amorphous viscoplasticity; most notably that "flow defects" in amorphous solids are characterized by internal states between which they can make transitions, and that structural evolution is driven by dissipation associated with plastic deformation. We present a rather extensive theoretical analysis of the thermodynamic shear-transformation-zone model for a variable-amplitude oscillatory shear protocol, highlighting its success in accounting for various experimental and simulational observations, as well as its limitations. Our results offer a continuum-level theoretical framework for interpreting the variable-amplitude oscillatory shear response of amorphous solids and may promote additional developments.

  7. Hidden variables and nonlocality in quantum mechanics

    NASA Astrophysics Data System (ADS)

    Hemmick, Douglas Lloyd

    1997-05-01

    Most physicists hold a skeptical attitude toward a 'hidden variables' interpretation of quantum theory, despite David Bohm's successful construction of such a theory and John S. Bell's strong arguments in favor of the idea. The first reason for doubt concerns certain mathematical theorems (von Neumann's, Gleason's, Kochen and Specker's, and Bell's) which can be applied to the hidden variables issue. These theorems are often credited with proving that hidden variables are indeed 'impossible', in the sense that they cannot replicate the predictions of quantum mechanics. Many who do not draw such a strong conclusion nevertheless accept that hidden variables have been shown to exhibit prohibitively complicated features. The second concern is that the most sophisticated example of a hidden variables theory-that of David Bohm-exhibits non-locality, i.e., consequences of events at one place can propagate to other places instantaneously. However, neither the mathematical theorems in question nor the attribute of nonlocality detract from the importance of a hidden variables interpretation of quantum theory. Nonlocality is present in quantum mechanics itself, and is a required characteristic of any theory that agrees with the quantum mechanical predictions. We first discuss the earliest analysis of hidden variables-that of von Neumann's theorem-and review John S. Bell's refutation of von Neumann's 'impossibility proof'. We recall and elaborate on Bell's arguments regarding the theorems of Gleason, and Kochen and Specker. According to Bell, these latter theorems do not imply that hidden variables interpretations are untenable, but instead that such theories must exhibit contextuality, i.e., they must allow for the dependence of measurement results on the characteristics of both measured system and measuring apparatus. We demonstrate a new way to understand the implications of both Gleason's theorem and Kochen and Specker's theorem by noting that they prove a result we call

  8. Phenibut dependence

    PubMed Central

    Samokhvalov, Andriy V; Paton-Gay, C Lindsay; Balchand, Kam; Rehm, Jürgen

    2013-01-01

    Phenibut is a γ-aminobutyric acid (GABA) agonist designed and used as an anxiolytic in Russia. In Western countries, phenibut is not a registered medication but is available through online stores as a supplement. We present a case of a patient who used phenibut to self-medicate anxiety, insomnia and cravings for alcohol. While phenibut was helpful initially, the patient developed dependence including tolerance, significant withdrawal symptoms within 3–4 h of last use and failure to fulfil his roles at work and at home. He finally sought medical assistance in our addictions clinic. We have gradually, over the course of 9 weeks, substituted phenibut with baclofen, which has similar pharmacological properties, and then successfully tapered the patient off baclofen. This required approximately 10 mg of baclofen for each gram of phenibut. PMID:23391959

  9. Time and space variability of spectral estimates of atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Canavero, Flavio G.; Einaudi, Franco

    1987-01-01

    The temporal and spatial behaviors of atmospheric pressure spectra over the northern Italy and the Alpine massif were analyzed using data on surface pressure measurements carried out at two microbarograph stations in the Po Valley, one 50 km south of the Alps, the other in the foothills of the Dolomites. The first 15 days of the study overlapped with the Alpex Intensive Observation Period. The pressure records were found to be intrinsically nonstationary and were found to display substantial time variability, implying that the statistical moments depend on time. The shape and the energy content of spectra depended on different time segments. In addition, important differences existed between spectra obtained at the two stations, indicating a substantial effect of topography, particularly for periods less than 40 min.

  10. Representing Uncertainty in Graph Edges: An Evaluation of Paired Visual Variables.

    PubMed

    Guo, Hua; Huang, Jeff; Laidlaw, David H

    2015-10-01

    When visualizing data with uncertainty, a common approach is to treat uncertainty as an additional dimension and encode it using a visual variable. The effectiveness of this approach depends on how the visual variables chosen for representing uncertainty and other attributes interact to influence the user's perception of each variable. We report a user study on the perception of graph edge attributes when uncertainty associated with each edge and the main edge attribute are visualized simultaneously using two separate visual variables. The study covers four visual variables that are commonly used for visualizing uncertainty on line graphical primitives: lightness, grain, fuzziness, and transparency. We select width, hue, and saturation for visualizing the main edge attribute and hypothesize that we can observe interference between the visual variable chosen to encode the main edge attribute and that to encode uncertainty, as suggested by the concept of dimensional integrality. Grouping the seven visual variables as color-based, focus-based, or geometry-based, we further hypothesize that the degree of interference is affected by the groups to which the two visual variables belong. We consider two further factors in the study: discriminability level for each visual variable as a factor intrinsic to the visual variables and graph-task type (visual search versus comparison) as a factor extrinsic to the visual variables. Our results show that the effectiveness of a visual variable in depicting uncertainty is strongly mediated by all the factors examined here. Focus-based visual variables (fuzziness, grain, and transparency) are robust to the choice of visual variables for encoding the main edge attribute, though fuzziness has stronger negative impact on the perception of width and transparency has stronger negative impact on the perception of hue than the other uncertainty visual variables. We found that interference between hue and lightness is much greater than that

  11. Alcohol dependence--classificatory considerations.

    PubMed

    Lesch, O M; Ades, J; Badawy, A; Pelc, I; Sasz, H

    1993-01-01

    The term alcoholism or alcohol dependence has acquired a broad range of meanings. The Plinius Maior Society herewith presents new classificatory considerations and suggests additional recording of special dimensions according to the individual hypothesis and design of a study.

  12. Nova-like variables

    NASA Technical Reports Server (NTRS)

    Ladous, Constanze

    1993-01-01

    On grounds of different observable characteristics five classes of nova-like objects are distinguished: the UX Ursae Majoris stars, the antidwarf novae, the DQ Herculis stars, the AM Herculis stars, and the AM Canum Venaticorum stars. Some objects have not been classified specifically. Nova-like stars share most observable features with dwarf novae, except for the outburst behavior. The understanding is that dwarf novae, UX Ursae Majoris stars, and anti-dwarf novae are basically the same sort of objects. The difference between them is that in UX Ursae Majoris stars the mass transfer through the accretion disc always is high so the disc is stationary all the time; in anti-dwarf novae for some reason the mass transfer occasionally drops considerably for some time, and in dwarf novae it is low enough for the disc to undergo semiperiodic changes between high and low accretion events. DQ Herculis stars are believed to possess weakly magnetic white dwarfs which disrupt the inner disc at some distance from the central star; the rotation of the white dwarf can be seen as an additional photometric period. In AM Herculis stars, a strongly magnetic white dwarf entirely prevents the formation of an accretion disk and at the same time locks the rotation of the white dwarf to the binary orbit. Finally, AM Canum Venaticorum stars are believed to be cataclysmic variables that consist of two white dwarf components.

  13. Common Variable Immunodeficiency.

    PubMed

    Saikia, Biman; Gupta, Sudhir

    2016-04-01

    Common variable immunodeficiency (CVID) is the most common primary immunodeficiency of young adolescents and adults which also affects the children. The disease remains largely under-diagnosed in India and Southeast Asian countries. Although in majority of cases it is sporadic, disease may be inherited in a autosomal recessive pattern and rarely, in autosomal dominant pattern. Patients, in addition to frequent sino-pulmonary infections, are also susceptible to various autoimmune diseases and malignancy, predominantly lymphoma and leukemia. Other characteristic lesions include lymphocytic and granulomatous interstitial lung disease, and nodular lymphoid hyperplasia of gut. Diagnosis requires reduced levels of at least two immunoglobulin isotypes: IgG with IgA and/or IgM and impaired specific antibody response to vaccines. A number of gene mutations have been described in CVID; however, these genetic alterations account for less than 20% of cases of CVID. Flow cytometry aptly demonstrates a disturbed B cell homeostasis with reduced or absent memory B cells and increased CD21(low) B cells and transitional B cell populations. Approximately one-third of patients with CVID also display T cell functional defects. Immunoglobulin therapy remains the mainstay of treatment. Immunologists and other clinicians in India and other South East Asian countries need to be aware of CVID so that early diagnosis can be made, as currently, majority of these patients still go undiagnosed. PMID:26868026

  14. Incorporation of additives into polymers

    DOEpatents

    McCleskey, T. Mark; Yates, Matthew Z.

    2003-07-29

    There has been invented a method for incorporating additives into polymers comprising: (a) forming an aqueous or alcohol-based colloidal system of the polymer; (b) emulsifying the colloidal system with a compressed fluid; and (c) contacting the colloidal polymer with the additive in the presence of the compressed fluid. The colloidal polymer can be contacted with the additive by having the additive in the compressed fluid used for emulsification or by adding the additive to the colloidal system before or after emulsification with the compressed fluid. The invention process can be carried out either as a batch process or as a continuous on-line process.

  15. Additive quantification on polymer thin films by ToF-SIMS: aging sample effects

    NASA Astrophysics Data System (ADS)

    Poleunis, Claude; Médard, Nicolas; Bertrand, Patrick

    2004-06-01

    Thin films (150 nm) of an amorphous polyester (polyethylene(terephthalate-isophthalate)) containing variable concentrations of an antioxidant (Irgafos™ 168) and a UV-stabilizer (Hostavin™ N30) have been prepared by spin-coating. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) results showed, in the case of a single additive system (antioxidant), that the additive intensity increased on the polymer surface during the first five aging days (exudation phenomenon), followed by an intensity decrease, which was related to the adsorption of hydrocarbon contaminations on the sample surface. This kinetic competition was observed whatever the used additive concentration. In the case of the binary additive system (antioxidant and UV-stabilizer), the antioxidant behavior was similar to the single additive system, whereas, the UV-stabilizer evolution corresponded to an additive depletion, followed by an exudation. These results indicate that it is necessary to be very careful when comparing ToF-SIMS data for additive quantification on polymer surfaces. It is strongly recommended to compare samples having the same aging time, because the surface composition was seen to be strongly dependent of the aging time.

  16. [Patch-testing methods: additional specialised or additional series].

    PubMed

    Cleenewerck, M-B

    2009-01-01

    The tests in the European standard battery must occasionally be supplemented by specialised or additional batteries, particularly where the contact allergy is thought to be of occupational origin. These additional batteries cover all allergens associated with various professional activities (hairdressing, baking, dentistry, printing, etc.) and with different classes of materials and chemical products (glue, plastic, rubber...). These additional tests may also include personal items used by patients on a daily basis such as cosmetics, shoes, plants, textiles and so on.

  17. Theoretical and experimental investigation of additive drag

    NASA Technical Reports Server (NTRS)

    Sibulkin, Merwin

    1954-01-01

    The significance of additive drag is discussed and equations for determining its approximate value are derived for annular and open-nose inlets. Charts are presented giving values of additive drag coefficient over a range of free-stream Mach numbers for open and for annular-nose inlets with conical flow at the inlet. The effects on additive drag of variable inlet-total-pressure recovery and static pressures on the centerbody are investigated and an analytical method of predicting the variation of pressure on the centerbody with mass-flow ratio is given. Experimental additive-drag values are presented for a series of 20 degree and 25 degree cone half-angle inlets and one open-nose inlet operating at free-stream Mach numbers of 1.8 and 1.6. A comparison with the theoretical values of additive drag shows excellent agreement for the open-nose inlet and moderately good agreement for the annular inlets. (author)

  18. Additive manufacturing of optical components

    NASA Astrophysics Data System (ADS)

    Heinrich, Andreas; Rank, Manuel; Maillard, Philippe; Suckow, Anne; Bauckhage, Yannick; Rößler, Patrick; Lang, Johannes; Shariff, Fatin; Pekrul, Sven

    2016-08-01

    The development of additive manufacturing methods has enlarged rapidly in recent years. Thereby, the work mainly focuses on the realization of mechanical components, but the additive manufacturing technology offers a high potential in the field of optics as well. Owing to new design possibilities, completely new solutions are possible. This article briefly reviews and compares the most important additive manufacturing methods for polymer optics. Additionally, it points out the characteristics of additive manufactured polymer optics. Thereby, surface quality is of crucial importance. In order to improve it, appropriate post-processing steps are necessary (e.g. robot polishing or coating), which will be discussed. An essential part of this paper deals with various additive manufactured optical components and their use, especially in optical systems for shape metrology (e.g. borehole sensor, tilt sensor, freeform surface sensor, fisheye lens). The examples should demonstrate the potentials and limitations of optical components produced by additive manufacturing.

  19. Medication dependence and anxiety

    PubMed Central

    von Moltke, Lisa L.; Greenblatt, David J.

    2003-01-01

    Anxiety disorders are common and costly psychiatric illnesses. Pharmacological treatment was enhanced with the introduction of benzodiazepines, which proved safer and more effective than older drugs. The risk of dependence, however, has made clinicians reluctant to use these medications. In fact, few patients appear to develop significant difficulties with these drugs, given how widely they are used. Careful planning for discontinuation of therapy is important. In addition, for some individuals, there appears to be a complex and as yet unelucidaied relationship between dependence on drugs or alcohol and anxiety. The newer antidepressants offer efficacy without abuse or dependence liability, but are expensive and have side effects that are intolerable for some patients. Pharmacological therapy for anxiety should be prescribed and managed so as to minimize any existing risk, while aiming to restore the patient to wellness in terms of symptoms and function. PMID:22033703

  20. Some new addition formulae for Weierstrass elliptic functions

    PubMed Central

    Eilbeck, J. Chris; England, Matthew; Ônishi, Yoshihiro

    2014-01-01

    We present new addition formulae for the Weierstrass functions associated with a general elliptic curve. We prove the structure of the formulae in n-variables and give the explicit addition formulae for the 2- and 3-variable cases. These new results were inspired by new addition formulae found in the case of an equianharmonic curve, which we can now observe as a specialization of the results here. The new formulae, and the techniques used to find them, also follow the recent work for the generalization of Weierstrass functions to curves of higher genus. PMID:25383018

  1. Greenland Glacier Albedo Variability

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The program for Arctic Regional Climate Assessment (PARCA) is a NASA-funded project with the prime goal of addressing the mass balance of the Greenland ice sheet. Since the formal initiation of the program in 1995, there has been a significant improvement in the estimates of the mass balance of the ice sheet. Results from this program reveal that the high-elevation regions of the ice sheet are approximately in balance, but the margins are thinning. Laser surveys reveal significant thinning along 70 percent of the ice sheet periphery below 2000 m elevations, and in at least one outlet glacier, Kangerdlugssuaq in southeast Greenland, thinning has been as much as 10 m/yr. This study examines the albedo variability in four outlet glaciers to help separate out the relative contributions of surface melting versus ice dynamics to the recent mass balance changes. Analysis of AVHRR Polar Pathfinder albedo shows that at the Petermann and Jakobshavn glaciers, there has been a negative trend in albedo at the glacier terminus from 1981 to 2000, whereas the Stor+strommen and Kangerdlugssuaq glaciers show slightly positive trends in albedo. These findings are consistent with recent observations of melt extent from passive microwave data which show more melt on the western side of Greenland and slightly less on the eastern side. Significance of albedo trends will depend on where and when the albedo changes occur. Since the majority of surface melt occurs in the shallow sloping western margin of the ice sheet where the shortwave radiation dominates the energy balance in summer (e.g. Jakobshavn region) this region will be more sensitive to changes in albedo than in regions where this is not the case. Near the Jakobshavn glacier, even larger changes in albedo have been observed, with decreases as much as 20 percent per decade.

  2. Understanding Brown Dwarf Variability

    NASA Technical Reports Server (NTRS)

    Marley, Mark S.

    2013-01-01

    Surveys of brown dwarf variability continue to find that roughly half of all brown dwarfs are variable. While variability is observed amongst all types of brown dwarfs, amplitudes are typically greatest for L-T transition objects. In my talk I will discuss the possible physical mechanisms that are responsible for the observed variability. I will particularly focus on comparing and contrasting the effects of changes in atmospheric thermal profile and cloud opacity. The two different mechanisms will produce different variability signatures and I will discuss the extent to which the current datasets constrain both mechanisms. By combining constraints from studies of variability with existing spectral and photometric datasets we can begin to construct and test self-consistent models of brown dwarf atmospheres. These models not only aid in the interpretation of existing objects but also inform studies of directly imaged giant planets.

  3. Enantioselective Michael Addition of Water

    PubMed Central

    Chen, Bi-Shuang; Resch, Verena; Otten, Linda G; Hanefeld, Ulf

    2015-01-01

    The enantioselective Michael addition using water as both nucleophile and solvent has to date proved beyond the ability of synthetic chemists. Herein, the direct, enantioselective Michael addition of water in water to prepare important β-hydroxy carbonyl compounds using whole cells of Rhodococcus strains is described. Good yields and excellent enantioselectivities were achieved with this method. Deuterium labeling studies demonstrate that a Michael hydratase catalyzes the water addition exclusively with anti-stereochemistry. PMID:25529526

  4. Enantioselective Michael addition of water.

    PubMed

    Chen, Bi-Shuang; Resch, Verena; Otten, Linda G; Hanefeld, Ulf

    2015-02-01

    The enantioselective Michael addition using water as both nucleophile and solvent has to date proved beyond the ability of synthetic chemists. Herein, the direct, enantioselective Michael addition of water in water to prepare important β-hydroxy carbonyl compounds using whole cells of Rhodococcus strains is described. Good yields and excellent enantioselectivities were achieved with this method. Deuterium labeling studies demonstrate that a Michael hydratase catalyzes the water addition exclusively with anti-stereochemistry.

  5. Adverse reactions to the sulphite additives

    PubMed Central

    Misso, Neil LA

    2012-01-01

    Sulphites are widely used as preservative and antioxidant additives in the food and pharmaceutical industries. Exposure to sulphites has been reported to induce a range of adverse clinical effects in sensitive individuals, ranging from dermatitis, urticaria, flushing, hypotension, abdominal pain and diarrhoea to life-threatening anaphylactic and asthmatic reactions. Exposure to the sulphites arises mainly from the consumption of foods and drinks that contain these additives; however exposure may also occur through the use of pharmaceutical products, as well as in occupational settings. Most studies report a prevalence of sulphite sensitivity of 3 to 10% among asthmatic subjects who ingest these additives. However, the severity of these reactions varies, and steroid-dependent asthmatics, those with marked airway hyperresponsiveness, and children with chronic asthma, appear to be at greater risk. Although a number of potential mechanisms have been proposed, the precise mechanisms underlying sulphite sensitivity remain unclear. PMID:24834193

  6. Thermal and structural analyses of variable thickness plane problems

    SciTech Connect

    Wang, Zhibi; Kuzay, T.M.

    1995-07-01

    Finite difference formulations for variable thickness thermal analysis and variable thickness plane stress analysis are presented. In heat transfer analysis, radiation effects and temperature-dependent thermal conductivity are taken into account. While in thermal stress analysis, the thermal expansion coefficient is considered as temperature dependent. An application of the variable thickness window for synchrotron radiation beamline under very strong X-ray is provided.

  7. Nonferromagnetic linear variable differential transformer

    DOEpatents

    Ellis, James F.; Walstrom, Peter L.

    1977-06-14

    A nonferromagnetic linear variable differential transformer for accurately measuring mechanical displacements in the presence of high magnetic fields is provided. The device utilizes a movable primary coil inside a fixed secondary coil that consists of two series-opposed windings. Operation is such that the secondary output voltage is maintained in phase (depending on polarity) with the primary voltage. The transducer is well-suited to long cable runs and is useful for measuring small displacements in the presence of high or alternating magnetic fields.

  8. Friedmann branes with variable tension

    SciTech Connect

    Gergely, Laszlo Arpad

    2008-10-15

    We introduce braneworlds with nonconstant tension, strengthening the analogy with fluid membranes, which exhibit a temperature dependence according to the empirical law established by Eoetvoes. This new degree of freedom allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We establish the covariant dynamics on a brane with variable tension in full generality, by considering asymmetrically embedded branes and allowing for nonstandard model fields in 5-dimensional space-time. Then we apply the formalism for a perfect fluid on a Friedmann brane, which is embedded in a 5-dimensional charged Vaidya-anti-de Sitter space-time.

  9. What is Optimum Variability?

    PubMed

    Schuldberg, David

    2015-10-01

    Guastello (2015a) opened the call for articles for this issue with Goldberger (1991) and colleagues' findings of chaotic variability in healthy heart rate, noting, 'the principle of healthy variability has extended to other biomedical and psychological phenomena.' He suggests a dialectical underpinning for optimal variability involving 'a combination of the minimum entropy or free energy principle that pushes in a downward direction, and Ashby's Law of Requisite Variety that pushes in an upward direction.' Each of the papers in this issue addresses optimal variability across a variety of health-related areas. The present article surveys these seven papers in relation to five conceptual questions about optimal variability: (a) Is variability a positive or a negative, and how are positive things related to health? (b) How shall we define and measure variability? (c) What constitutes an optimum, and how do we locate one? (d) What is the relationship between optimum variability and health? Finally, it touches on (e) What are underlying principles and phenomena behind healthy variability, and can they inform our vocabulary for health? The paper concludes by discussing practical approaches to dealing with optimization. PMID:26375940

  10. VARIABLE TIME DELAY MEANS

    DOEpatents

    Clemensen, R.E.

    1959-11-01

    An electrically variable time delay line is described which may be readily controlled simuitaneously with variable impedance matching means coupied thereto such that reflections are prevented. Broadly, the delay line includes a signal winding about a magnetic core whose permeability is electrically variable. Inasmuch as the inductance of the line varies directly with the permeability, the time delay and characteristic impedance of the line both vary as the square root of the permeability. Consequently, impedance matching means may be varied similariy and simultaneously w:th the electrically variable permeability to match the line impedance over the entire range of time delay whereby reflections are prevented.

  11. The ROSAT variable sky

    NASA Technical Reports Server (NTRS)

    Angelini, L.; Giommi, P.; White, N. E.

    1996-01-01

    The spectral and timing characteristics from a sample, of 91 objects, of the variable sources obtained using the Kolmogorov-Smirnov test technique are presented. The data were extracted from the catalog constructed by White, Giommi and Angelini, the WGACAT, based on the pointed observations from the Rosat missions. The application of the test revealed more than 2400 individual variable candidates, with 'sq chi' greater than 12. The sample of these variable sources, mostly unidentified, probably contains many flare stars, a few cataclysmic variables and a possible transient source.

  12. Radiation-induced DNA content variability in mouse sperm

    SciTech Connect

    Pinkel, D.; Gledhill, B.L.; Van Dilla, M.A.; Lake, S.; Wyrobek, A.J.

    1983-09-01

    Mouse sperm collected from the cauda epididymidis 35 days after acute testicular X-ray exposure and fluorescently stained for DNA show dose-dependent increases in the coefficient of variation (CV) of flow cytometrically obtained fluorescence distributions. By comparing dose-response curves obtained with three protocols which overcome the optical and cytochemical difficulties of sperm measurement in different ways we conclude the response is due to X-ray-induced DNA content variability. In the range between 0 and 600 rad the dose dependence of the square of CV of the DNA content variability, delta CV2D, is described by delta CV2D . Bx + Cx2, with 0 less than or equal to B less than or equal to 0.23 X 10(-2) and C . (0.44 +/- 0.06) X 10(-4). The dose x is measured in rad and delta CVD is expressed in percent. Computer modeling of the shapes of the fluorescence distributions show that at 600 rad 30 to 40% of the sperm have abnormal DNA content. Some have errors as large as two whole chromosomes, but it is not clear whether they are due to whole chromosome nondisjunction or a finer fragmentation of the genome. Exposures to benzo(a)pyrene and mitomycin C cause no detectable DNA content variability. We conclude mouse sperm DNA content measurements are not sensitive to small amounts of aneuploidy and as such will only be useful in detecting agents that produce substantial DNA content variability. Another animal with a smaller number of chromosomes might be more favorable. These sperm measurement techniques may find additional application in other areas of reproductive biology, such as the determination of the relative numbers of X and Y chromosome-bearing sperm in semen that may be artificially enriched in one population.

  13. Bounds on internal state variables in viscoplasticity

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1993-01-01

    A typical viscoplastic model will introduce up to three types of internal state variables in order to properly describe transient material behavior; they are as follows: the back stress, the yield stress, and the drag strength. Different models employ different combinations of these internal variables--their selection and description of evolution being largely dependent on application and material selection. Under steady-state conditions, the internal variables cease to evolve and therefore become related to the external variables (stress and temperature) through simple functional relationships. A physically motivated hypothesis is presented that links the kinetic equation of viscoplasticity with that of creep under steady-state conditions. From this hypothesis one determines how the internal variables relate to one another at steady state, but most importantly, one obtains bounds on the magnitudes of stress and back stress, and on the yield stress and drag strength.

  14. Predictive Inference Using Latent Variables with Covariates*

    PubMed Central

    Schofield, Lynne Steuerle; Junker, Brian; Taylor, Lowell J.; Black, Dan A.

    2014-01-01

    Plausible Values (PVs) are a standard multiple imputation tool for analysis of large education survey data that measures latent proficiency variables. When latent proficiency is the dependent variable, we reconsider the standard institutionally-generated PV methodology and find it applies with greater generality than shown previously. When latent proficiency is an independent variable, we show that the standard institutional PV methodology produces biased inference because the institutional conditioning model places restrictions on the form of the secondary analysts’ model. We offer an alternative approach that avoids these biases based on the mixed effects structural equations (MESE) model of Schofield (2008). PMID:25231627

  15. Color Addition and Subtraction Apps

    ERIC Educational Resources Information Center

    Ruiz, Frances; Ruiz, Michael J.

    2015-01-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step…

  16. [The research protocol IV: study variables].

    PubMed

    Villasís-Keever, Miguel Ángel; Miranda-Novales, María Guadalupe

    2016-01-01

    The variables in a research study are all that is measured, the information collected, or the data that is collected in order to answer the research questions, which are specified in the objectives. Their selection is essential to the research protocol. This article aims to point out the elements to be considered in the section of the variables. To avoid ambiguity, it is necessary to select only those that will help achieve the study objectives. It should subsequently be defined how they will be measured to ensure that the findings can be replicated; it is therefore desirable to include conceptual and operational definitions. From the methodological point of view, the classification of variables helps us understand how the relationship between them is conceptualized. Depending on the study design, the independent, dependent, universal, and confounding variables should be noted. Another indispensable element for planning statistical analyses is the scale of variable measurement. Therefore, one must specify whether the variables correspond to one of the following four: qualitative nominal, qualitative ordinal, quantitative range, or quantitative ratio. Finally, we should detail the measurement units of each variable. PMID:27560918

  17. [The research protocol IV: study variables].

    PubMed

    Villasís-Keever, Miguel Ángel; Miranda-Novales, María Guadalupe

    2016-01-01

    The variables in a research study are all that is measured, the information collected, or the data that is collected in order to answer the research questions, which are specified in the objectives. Their selection is essential to the research protocol. This article aims to point out the elements to be considered in the section of the variables. To avoid ambiguity, it is necessary to select only those that will help achieve the study objectives. It should subsequently be defined how they will be measured to ensure that the findings can be replicated; it is therefore desirable to include conceptual and operational definitions. From the methodological point of view, the classification of variables helps us understand how the relationship between them is conceptualized. Depending on the study design, the independent, dependent, universal, and confounding variables should be noted. Another indispensable element for planning statistical analyses is the scale of variable measurement. Therefore, one must specify whether the variables correspond to one of the following four: qualitative nominal, qualitative ordinal, quantitative range, or quantitative ratio. Finally, we should detail the measurement units of each variable.

  18. Interactively variable isotropic resolution in computed tomography

    NASA Astrophysics Data System (ADS)

    Lapp, Robert M.; Kyriakou, Yiannis; Kachelrieß, Marc; Wilharm, Sylvia; Kalender, Willi A.

    2008-05-01

    An individual balancing between spatial resolution and image noise is necessary to fulfil the diagnostic requirements in medical CT imaging. In order to change influencing parameters, such as reconstruction kernel or effective slice thickness, additional raw-data-dependent image reconstructions have to be performed. Therefore, the noise versus resolution trade-off is time consuming and not interactively applicable. Furthermore, isotropic resolution, expressed by an equivalent point spread function (PSF) in every spatial direction, is important for the undistorted visualization and quantitative evaluation of small structures independent of the viewing plane. Theoretically, isotropic resolution can be obtained by matching the in-plane and through-plane resolution with the aforementioned parameters. Practically, however, the user is not assisted in doing so by current reconstruction systems and therefore isotropic resolution is not commonly achieved, in particular not at the desired resolution level. In this paper, an integrated approach is presented for equalizing the in-plane and through-plane spatial resolution by image filtering. The required filter kernels are calculated from previously measured PSFs in x/y- and z-direction. The concepts derived are combined with a variable resolution filtering technique. Both approaches are independent of CT raw data and operate only on reconstructed images which allows for their application in real time. Thereby, the aim of interactively variable, isotropic resolution is achieved. Results were evaluated quantitatively by measuring PSFs and image noise, and qualitatively by comparing the images to direct reconstructions regarded as the gold standard. Filtered images matched direct reconstructions with arbitrary reconstruction kernels with standard deviations in difference images of typically between 1 and 17 HU. Isotropic resolution was achieved within 5% of the selected resolution level. Processing times of 20-100 ms per frame

  19. A novel variable selection approach that iteratively optimizes variable space using weighted binary matrix sampling.

    PubMed

    Deng, Bai-chuan; Yun, Yong-huan; Liang, Yi-zeng; Yi, Lun-zhao

    2014-10-01

    In this study, a new optimization algorithm called the Variable Iterative Space Shrinkage Approach (VISSA) that is based on the idea of model population analysis (MPA) is proposed for variable selection. Unlike most of the existing optimization methods for variable selection, VISSA statistically evaluates the performance of variable space in each step of optimization. Weighted binary matrix sampling (WBMS) is proposed to generate sub-models that span the variable subspace. Two rules are highlighted during the optimization procedure. First, the variable space shrinks in each step. Second, the new variable space outperforms the previous one. The second rule, which is rarely satisfied in most of the existing methods, is the core of the VISSA strategy. Compared with some promising variable selection methods such as competitive adaptive reweighted sampling (CARS), Monte Carlo uninformative variable elimination (MCUVE) and iteratively retaining informative variables (IRIV), VISSA showed better prediction ability for the calibration of NIR data. In addition, VISSA is user-friendly; only a few insensitive parameters are needed, and the program terminates automatically without any additional conditions. The Matlab codes for implementing VISSA are freely available on the website: https://sourceforge.net/projects/multivariateanalysis/files/VISSA/.

  20. The WFCAM multiwavelength Variable Star Catalog

    NASA Astrophysics Data System (ADS)

    Ferreira Lopes, C. E.; Dékány, I.; Catelan, M.; Cross, N. J. G.; Angeloni, R.; Leão, I. C.; De Medeiros, J. R.

    2015-01-01

    Context. Stellar variability in the near-infrared (NIR) remains largely unexplored. The exploitation of public science archives with data-mining methods offers a perspective for a time-domain exploration of the NIR sky. Aims: We perform a comprehensive search for stellar variability using the optical-NIR multiband photometric data in the public Calibration Database of the WFCAM Science Archive (WSA), with the aim of contributing to the general census of variable stars and of extending the current scarce inventory of accurate NIR light curves for a number of variable star classes. Methods: Standard data-mining methods were applied to extract and fine-tune time-series data from the WSA. We introduced new variability indices designed for multiband data with correlated sampling, and applied them for preselecting variable star candidates, i.e., light curves that are dominated by correlated variations, from noise-dominated ones. Preselection criteria were established by robust numerical tests for evaluating the response of variability indices to the colored noise characteristic of the data. We performed a period search using the string-length minimization method on an initial catalog of 6551 variable star candidates preselected by variability indices. Further frequency analysis was performed on positive candidates using three additional methods in combination, in order to cope with aliasing. Results: We find 275 periodic variable stars and an additional 44 objects with suspected variability with uncertain periods or apparently aperiodic variation. Only 44 of these objects had been previously known, including 11 RR Lyrae stars on the outskirts of the globular cluster M 3 (NGC 5272). We provide a preliminary classification of the new variable stars that have well-measured light curves, but the variability types of a large number of objects remain ambiguous. We classify most of the new variables as contact binary stars, but we also find several pulsating stars, among which

  1. A variety of variables.

    PubMed

    Jupiter, Daniel C

    2014-01-01

    In designing studies and developing plans for analyses, we must consider which tests are appropriate for the types of variables we are using. Here I describe the types of variables available to us, and I briefly consider the appropriate tools to use in their analysis.

  2. Variable Density Tunnel

    NASA Technical Reports Server (NTRS)

    1931-01-01

    Variable Density Tunnel in operation. Man at far right is probably Harold J. 'Cannonball' Tuner, longtime safety officer, who started with Curtiss in the teens. This view of the Variable Density Tunnel clearly shows the layout of the Tunnel's surroundings, as well as the plumbing and power needs of the this innovative research tool.

  3. Latent Variable Interaction Modeling.

    ERIC Educational Resources Information Center

    Schumacker, Randall E.

    2002-01-01

    Used simulation to study two different approaches to latent variable interaction modeling with continuous observed variables: (1) a LISREL 8.30 program and (2) data analysis through PRELIS2 and SIMPLIS programs. Results show that parameter estimation was similar but standard errors were different. Discusses differences in ease of implementation.…

  4. Reinforcing Saccadic Amplitude Variability

    ERIC Educational Resources Information Center

    Paeye, Celine; Madelain, Laurent

    2011-01-01

    Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we…

  5. Basic properties and variability

    NASA Technical Reports Server (NTRS)

    Querci, Francois R.

    1987-01-01

    Giant and supergiant M, S, and C stars are discussed in this survey of research. Basic properties as determined by spectra, chemical composition, photometry, or variability type are discussed. Space motions and space distributions of cool giants are described. Distribution of these stars in our galaxy and those nearby is discussed. Mira variables in particular are surveyed with emphasis on the following topics: (1) phase lag phenomenon; (2) Mira light curves; (3) variations in color indices; (4) determination of multiple periods; (5) correlations between quantities such as period length, light-curve shape, infrared (IR) excess, and visible and IR color diagram; (6) semiregular (SR) variables and different time scales in SR light variations; (7) irregular variable Lb and Lc stars; (8) different time-scale light variations; (9) hydrogen-deficient carbon (HdC) stars, in particular RCB stars; and (10) irreversible changes and rapid evolution in red variable stars.

  6. Color Addition and Subtraction Apps

    NASA Astrophysics Data System (ADS)

    Ruiz, Frances; Ruiz, Michael J.

    2015-10-01

    Color addition and subtraction apps in HTML5 have been developed for students as an online hands-on experience so that they can more easily master principles introduced through traditional classroom demonstrations. The evolution of the additive RGB color model is traced through the early IBM color adapters so that students can proceed step by step in understanding mathematical representations of RGB color. Finally, color addition and subtraction are presented for the X11 colors from web design to illustrate yet another real-life application of color mixing.

  7. Trends and variability in East African rainfall and temperature observations

    NASA Astrophysics Data System (ADS)

    Seregina, Larisa; Ermert, Volker; Fink, Andreas H.; Pinto, Joaquim G.

    2014-05-01

    The economy of East Africa is highly dependent on agriculture, leading to a strong vulnerability of local society to fluctuations in seasonal rainfall amounts, including extreme events. Hence, the knowledge about the evolution of seasonal rainfall under future climate conditions is crucial. Rainfall regimes over East Africa are influenced by multiple factors, including two monsoon systems, several convergence zones and the Rift Valley lakes. In addition, local conditions, like topography, modulate the large-scale rainfall pattern. East African rainfall variability is also influenced by various teleconnections like the Indian Ocean Zonal Mode and El Niño Southern Oscillation. Regarding future climate projections, regional and global climate models partly disagree on the increase or decrease of East African rainfall. The specific aim of the present study is the acquirement of historic data from weather stations in East Africa (Kenya, Tanzania, Ruanda and Uganda), the use of gridded satellite (rainfall) products (ARC2 and TRMM), and three-dimensional atmospheric reanalysis (e.g., ERA-Interim) to quantify climate variability in the recent past and to understand its causes. Climate variability and trends, including changes in extreme events, are evaluated using ETCCDI climate change and standardized precipitation indices. These climate indices are determined in order to investigate the variability of temperature and rainfall and their trends with the focus on most recent decades. In the follow-up, statistical and dynamical analyses are conducted to quantify the local impact of pertinent large-scale modes of climate variability (Indian Ocean Zonal Mode, El Niño Southern Oscillation, Sea Surface Temperature of the Indian Ocean).

  8. Contingency management is effective across cocaine-dependent outpatients with different socioeconomic status.

    PubMed

    Secades-Villa, Roberto; García-Fernández, Gloria; Peña-Suárez, Elsa; García-Rodríguez, Olaya; Sánchez-Hervás, Emilio; Fernández-Hermida, José Ramón

    2013-03-01

    Contingency management (CM) has demonstrated its efficacy for treating cocaine dependence, but there is still some controversy with regard to its dissemination. Understanding how individual differences affect CM outcomes is important for detecting barriers to its dissemination. The aim of this study is to examine the impact of socioeconomic variables in cocaine-dependent outpatients on the effectiveness of CM in a community setting. Cocaine-dependent outpatients (N=118) were randomized to community reinforcement approach (CRA) treatment or a CRA plus vouchers program. The impact of baseline economic variables, alone and in combination with treatment conditions, on abstinence and retention outcomes after 6 months of treatment was assessed. Results showed that income had no effect on retention or abstinence outcomes after 6 months of treatment in either treatment condition. The addition of a CM component was beneficial for individuals with any socioeconomic status. These results support the generalizability of CM strategies with patients of different socioeconomic status in community settings.

  9. Teebi hypertelorism syndrome: additional cases.

    PubMed

    Machado-Paula, Ligiane Alves; Guion-Almeida, Maria Leine

    2003-03-01

    We report on two unrelated Brazilian boys who have craniofacial and digital anomalies resembling those reported with Teebi hypertelorism syndrome. Additional features such as cleft lip and palate, large uvula, atypical chin and abnormal scapulae were observed.

  10. Motivational and psychological correlates of bodybuilding dependence

    PubMed Central

    EMINI, NEIM N.; BOND, MALCOLM J.

    2014-01-01

    Abstract Background and aims: Exercise may become physically and psychologically maladaptive if taken to extremes. One example is the dependence reported by some individuals who engage in weight training. The current study explored potential psychological, motivational, emotional and behavioural concomitants of bodybuilding dependence, with a particular focus on motives for weight training. Using a path analysis paradigm, putative causal models sought to explain associations among key study variables. Methods: A convenience sample of 101 men aged between 18 and 67 years was assembled from gymnasia in Adelaide, South Australia. Active weight trainers voluntarily completed a questionnaire that included measures of bodybuilding dependence (social dependency, training dependency, and mastery), anger, hostility and aggression, stress and motivations for weight training. Results: Three motives for weight training were identified: mood control, physique anxiety and personal challenge. Of these, personal challenge and mood control were the most directly salient to dependence. Social dependency was particularly relevant to personal challenge, whereas training dependency was associated with both personal challenge and mood control. Mastery demonstrated a direct link with physique anxiety, thus reflecting a unique component of exercise dependence. Conclusions: While it was not possible to determine causality with the available data, the joint roles of variables that influence, or are influenced by, bodybuilding dependence are identified. Results highlight unique motivations for bodybuilding and suggest that dependence could be a result of, and way of coping with, stress manifesting as aggression. A potential framework for future research is provided through the demonstration of plausible causal linkages among these variables. PMID:25317342

  11. Operant variability and voluntary action.

    PubMed

    Neuringer, Allen; Jensen, Greg

    2010-07-01

    A behavior-based theory identified 2 characteristics of voluntary acts. The first, extensively explored in operant-conditioning experiments, is that voluntary responses produce the reinforcers that control them. This bidirectional relationship-in which reinforcer depends on response and response on reinforcer-demonstrates the functional nature of the voluntary act. The present article focuses on the second characteristic: a similar bidirectional relationship between reinforcement and the predictability/unpredictability of voluntary acts. Support for the theory comes from 2 areas of research. The first shows that levels of behavioral variability-from highly predictable to randomlike-are directly influenced by reinforcers. Put another way, variability is an operant dimension, analogous to response rate and force. The second source of support comes from psychophysical experiments in which human participants judged the degree to which "choices" by virtual actors on a computer screen appeared to be voluntary. The choices were intermittently reinforced according to concurrently operating schedules. The actors' behaviors appeared to most closely approximate voluntary human choices when response distributions matched reinforcer distributions (an indication of functionality) and when levels of variability, from repetitive to random, changed with reinforcement contingencies. Thus, voluntary acts are characterized by reinforcement-controlled functionality and unpredictability.

  12. Operant variability and voluntary action.

    PubMed

    Neuringer, Allen; Jensen, Greg

    2010-07-01

    A behavior-based theory identified 2 characteristics of voluntary acts. The first, extensively explored in operant-conditioning experiments, is that voluntary responses produce the reinforcers that control them. This bidirectional relationship-in which reinforcer depends on response and response on reinforcer-demonstrates the functional nature of the voluntary act. The present article focuses on the second characteristic: a similar bidirectional relationship between reinforcement and the predictability/unpredictability of voluntary acts. Support for the theory comes from 2 areas of research. The first shows that levels of behavioral variability-from highly predictable to randomlike-are directly influenced by reinforcers. Put another way, variability is an operant dimension, analogous to response rate and force. The second source of support comes from psychophysical experiments in which human participants judged the degree to which "choices" by virtual actors on a computer screen appeared to be voluntary. The choices were intermittently reinforced according to concurrently operating schedules. The actors' behaviors appeared to most closely approximate voluntary human choices when response distributions matched reinforcer distributions (an indication of functionality) and when levels of variability, from repetitive to random, changed with reinforcement contingencies. Thus, voluntary acts are characterized by reinforcement-controlled functionality and unpredictability. PMID:20658860

  13. Polyolefins as additives in plastics

    SciTech Connect

    Deanin, R.D.

    1993-12-31

    Polyolefins are not only major commodity plastics - they are also very useful as additives, both in other polyolefins and also in other types of plastics. This review covers ethylene, propylene, butylene and isobutylene polymers, in blends with each other, and as additives to natural rubber, styrene/butadiene rubber, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyphenylene oxide, polycarbonate, thermoplastic polyesters, polyurethanes, polyamides, and mixed automotive plastics recycling.

  14. Variables Associated With Tic Exacerbation in Children With Chronic Tic Disorders

    PubMed Central

    Himle, Michael B.; Capriotti, Matthew R.; Hayes, Loran P.; Ramanujam, Krishnapriya; Scahill, Lawrence; Sukhodolsky, Denis G.; Wilhelm, Sabine; Deckersbach, Thilo; Peterson, Alan L.; Specht, Matt W.; Walkup, John T.; Chang, Susanna; Piacentini, John

    2014-01-01

    Research has shown that motor and vocal tics fluctuate in frequency, intensity, and form in response to environmental and contextual cues. Behavioral models have proposed that some of the variation in tics may reflect context-dependent interactive learning processes such that once tics are performed, they are influenced by environmental contingencies. The current study describes the results of a function-based assessment of tics (FBAT) from a recently completed study comparing Comprehensive Behavioral Intervention for Tics (CBIT) with supportive psychotherapy. The current study describes the frequency with which antecedent and consequence variables were reported to exacerbate tics and the relationships between these functional variables and sample baseline characteristics, comorbidities, and measures of tic severity. Results showed that tic-exacerbating antecedents and consequences were nearly ubiquitous in a sample of children with chronic tic disorder. In addition, functional variables were related to baseline measures of comorbid internalizing symptoms and specific measures of tic severity. PMID:24778433

  15. Variables Associated With Tic Exacerbation in Children With Chronic Tic Disorders.

    PubMed

    Himle, Michael B; Capriotti, Matthew R; Hayes, Loran P; Ramanujam, Krishnapriya; Scahill, Lawrence; Sukhodolsky, Denis G; Wilhelm, Sabine; Deckersbach, Thilo; Peterson, Alan L; Specht, Matt W; Walkup, John T; Chang, Susanna; Piacentini, John

    2014-03-01

    Research has shown that motor and vocal tics fluctuate in frequency, intensity, and form in response to environmental and contextual cues. Behavioral models have proposed that some of the variation in tics may reflect context-dependent interactive learning processes such that once tics are performed, they are influenced by environmental contingencies. The current study describes the results of a function-based assessment of tics (FBAT) from a recently completed study comparing Comprehensive Behavioral Intervention for Tics (CBIT) with supportive psychotherapy. The current study describes the frequency with which antecedent and consequence variables were reported to exacerbate tics and the relationships between these functional variables and sample baseline characteristics, comorbidities, and measures of tic severity. Results showed that tic-exacerbating antecedents and consequences were nearly ubiquitous in a sample of children with chronic tic disorder. In addition, functional variables were related to baseline measures of comorbid internalizing symptoms and specific measures of tic severity.

  16. Food additives and preschool children.

    PubMed

    Martyn, Danika M; McNulty, Breige A; Nugent, Anne P; Gibney, Michael J

    2013-02-01

    Food additives have been used throughout history to perform specific functions in foods. A comprehensive framework of legislation is in place within Europe to control the use of additives in the food supply and ensure they pose no risk to human health. Further to this, exposure assessments are regularly carried out to monitor population intakes and verify that intakes are not above acceptable levels (acceptable daily intakes). Young children may have a higher dietary exposure to chemicals than adults due to a combination of rapid growth rates and distinct food intake patterns. For this reason, exposure assessments are particularly important in this age group. The paper will review the use of additives and exposure assessment methods and examine factors that affect dietary exposure by young children. One of the most widely investigated unfavourable health effects associated with food additive intake in preschool-aged children are suggested adverse behavioural effects. Research that has examined this relationship has reported a variety of responses, with many noting an increase in hyperactivity as reported by parents but not when assessed using objective examiners. This review has examined the experimental approaches used in such studies and suggests that efforts are needed to standardise objective methods of measuring behaviour in preschool children. Further to this, a more holistic approach to examining food additive intakes by preschool children is advisable, where overall exposure is considered rather than focusing solely on behavioural effects and possibly examining intakes of food additives other than food colours.

  17. Variable Gain Semiconductor Optical Linear Amplifier (OLA)

    NASA Astrophysics Data System (ADS)

    Michie, W. Craig; Kelly, Tony; Tomlinson, Andy; Andonovic, Ivan

    2002-12-01

    The semiconductor optical amplifier (SOA) is a versatile component that can be deployed to meet the expanding applications associated with the introduction of additional functionalities at the optical level in wavelength division multiplexed systems. The future network requires low cost, small footprint, directly controllable amplification throughout the different application layers from long haul through to metro; the intrinsic size and integration capability advantages will ensure that the SOA plays a key role in this evolution. In multi-wavelength gating/amplification applications the gain dynamics, oscillating at timescales comparable to that of the data which is being amplified, introduce issues of pattern dependent waveform distortion (patterning) in single channel, and inter-channel cross-talk in multi-wavelength cases which require management through careful SOA design and understanding of the network application scenarios. In this paper, an optical linear amplifier (OLA) architecture with the unique capability to provide variable gain whilst maintaining linear operation at high output saturation powers will be described. Initial characterisation results for the OLA will be presented.

  18. Variability in the management of lithium poisoning.

    PubMed

    Roberts, Darren M; Gosselin, Sophie

    2014-01-01

    Three patterns of lithium poisoning are recognized: acute, acute-on-chronic, and chronic. Intravenous fluids with or without an extracorporeal treatment are the mainstay of treatment; their respective roles may differ depending on the mode of poisoning being treated. Recommendations for treatment selection are available but these are based on a small number of observational studies and their uptake by clinicians is not known. Clinician decision-making in the treatment of four cases of lithium poisoning was assessed at a recent clinical toxicology meeting using an audience response system. Variability in treatment decisions was evident in addition to discordance with published recommendations. Participants did not consistently indicate that hemodialysis was the first-line treatment, instead opting for a conservative approach, and continuous modalities were viewed favorably; this is in contrast to recommendations in some references. The development of multidisciplinary consensus guidelines may improve the management of patients with lithium poisoning but prospective randomized controlled trials are required to more clearly define the role of extracorporeal treatments.

  19. Adaptive Variability in Skilled Human Movements

    NASA Astrophysics Data System (ADS)

    Kudo, Kazutoshi; Ohtsuki, Tatsuyuki

    Human movements are produced in variable external/internal environments. Because of this variability, the same motor command can result in quite different movement patterns. Therefore, to produce skilled movements humans must coordinate the variability, not try to exclude it. In addition, because human movements are produced in redundant and complex systems, a combination of variability should be observed in different anatomical/physiological levels. In this paper, we introduce our research about human movement variability that shows remarkable coordination among components, and between organism and environment. We also introduce nonlinear dynamical models that can describe a variety of movements as a self-organization of a dynamical system, because the dynamical systems approach is a major candidate to understand the principle underlying organization of varying systems with huge degrees-of-freedom.

  20. Multi-Time-Scale Variability of Stars

    NASA Astrophysics Data System (ADS)

    Andronov, I. L.

    Physical mechanisms and corresponding mathematical models for different types of stellar variability are reviewed with applications to concrete stars. Special attention is attributed to the following topics: cataclysmic variables (synchronous and synchronizing magnetic systems, non-magnetic novalike stars, dwarf novae; magnetic activity of the red companion, third body around), pulsating variables (additional classification criteria of variability, multiparameter correlation analysis of the characteristics of the mean light curves of groups of long-period stars and of the multi- parameter correlation analysis of the individual characteristics of their pulsations), mathematical models (multi-periodic, multi-harmonic, multi-shift variations with possible trends, mono- and multi- cyclic variations of low coherence and the frequency changing/switching signals, "red noise" variability. Some original papers and links may be found at http://ila.webjump.com

  1. Ionospheric variability over Japan

    NASA Astrophysics Data System (ADS)

    Ezquer, R. G.; Mosert, M.; Corbella, R.; Erazu, M.; de La Zerda, L.

    The understanding of ionospheric variability is important for the user of ionospheric models. A satellite designer or operator needs to know not only monthly average conditions but also the expected deviations from these mean values. In order to contribute to the studies on ionospheric variability, in this paper values of critical frequencies of F2, F1 and E regions and M(3000)F2 factor measured at 4 Japanese stations are used. Data correspond to equinoxes, solstices, high and low solar activity. Quartiles and median values are used to specify variability, because they have the advantage of being less affected by large deviations that can occur during magnetic storms. The results are similar for the considered stations and show that the highest variability correspond to foF2. For March high solar activity the variability of fof2 decreases during hours of maximum ionisation. The M3000F2 factor, in general, shown low variability. Akita (39.72° N, 140.13° E) showed the highest variability for the three frequencies. Moreover, it can be seen that quartiles are not equidistant from the median value.

  2. Differential equations of time dependent order

    NASA Astrophysics Data System (ADS)

    Ludu, A.

    2016-10-01

    We introduce a special type of ordinary differential equations dx x/dtx = f (t, x) whose order of differentiation is a continuous variable depending on the dependent x or independent t variables. We show that such variable order of differentiation equations (VODE) can be solved as Volterra integral equations of second kind with singular integrable kernel. We find the conditions for existence and uniqueness of solutions of such VODE, and present some numeric solutions for particular cases exhibiting bifurcations and blow-up.

  3. Radiation-induced DNA content variability in mouse sperm

    SciTech Connect

    Pinkel, D.; Gledhill, B.L.; van Dilla, M.A.; Lake, S.; Wyrobek, A.J.

    1983-09-01

    Mouse sperm collected from the cauda epididymidis 35 days after acute testicular x-ray exposure and fluorescently stained for DNA show dose-dependent increases in the coefficient of variation (CV) of flow cytometrically obtained fluorescence distributions. By comparing dose-response curves obtained with three protocols which overcome the optical and cytochemical difficulties of sperm measurement in different ways we conclude the response is due to x-ray-induced DNA content variability. Computer modeling of the shapes of the fluorescence distributions show that at 600 rad 30 to 40% of the sperm have abnormal DNA content. Some have errors as large as two whole chromosomes, but it is not clear whether they are due to whole chromosome nondisjunction or a finer fragmentation of the genome. Exposures to benzo(a)pyrene and mitomycin C cause no detectable DNA content variability. We conclude mouse sperm DNA content measurements are not sensitive to small amounts of aneuploidy and as such will only be useful in detecting agents that produce substantial DNA content variability. Another animal with a smaller number of chromosomes might be more favorable. These sperm measurement techniques may find additional application in other areas of reproductive biology, such as the determination of the relative numbers of X and Y chromosome-bearing sperm in semen that may be artifically enriched in one population.

  4. Variability study for saltstone

    SciTech Connect

    Harbour, J. R.; Edwards, T. B.; Hansen, E. K.; Williams, V. J.

    2005-10-01

    This report is a summary of the bench-scale experimental studies performed by the Savannah River National Laboratory (SRNL) for Waste Solidification Engineering (WSE) to establish the viability of a grout-based variability study. In order for a variability study to be useful, the property measurements of the fresh and cured Saltstone must be reproducible with an inherent variation that is small compared to the changes in the properties measured over the expected range of variability for a Salt Batch. This scoping task addressed the issue of reproducibility for Saltstone.

  5. A space and time scale-dependent nonlinear geostatistical approach for downscaling daily precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Jha, Sanjeev Kumar; Mariethoz, Gregoire; Evans, Jason; McCabe, Matthew F.; Sharma, Ashish

    2015-08-01

    A geostatistical framework is proposed to downscale daily precipitation and temperature. The methodology is based on multiple-point geostatistics (MPS), where a multivariate training image is used to represent the spatial relationship between daily precipitation and daily temperature over several years. Here the training image consists of daily rainfall and temperature outputs from the Weather Research and Forecasting (WRF) model at 50 and 10 km resolution for a 20 year period ranging from 1985 to 2004. The data are used to predict downscaled climate variables for the year 2005. The result, for each downscaled pixel, is daily time series of precipitation and temperature that are spatially dependent. Comparison of predicted precipitation and temperature against a reference data set indicates that both the seasonal average climate response together with the temporal variability are well reproduced. The explicit inclusion of time dependence is explored by considering the climate properties of the previous day as an additional variable. Comparison of simulations with and without inclusion of time dependence shows that the temporal dependence only slightly improves the daily prediction because the temporal variability is already well represented in the conditioning data. Overall, the study shows that the multiple-point geostatistics approach is an efficient tool to be used for statistical downscaling to obtain local-scale estimates of precipitation and temperature from General Circulation Models.

  6. The effects of US state income inequality and alcohol policies on symptoms of depression and alcohol dependence.

    PubMed

    Henderson, Claire; Liu, Xinhua; Diez Roux, Ana V; Link, Bruce G; Hasin, Deborah

    2004-02-01

    Mental health is likely to be influenced by contextual variables that emerge only at the level of the group. We studied the effect of two such group-level variables, within-state income inequality and alcohol tax policy, on symptoms of current depression and alcohol dependence in a US national sample, controlling for state-level and individual characteristics. A cross-sectional US national probability sample provided the individual-level data. State income data were obtained from the 1990 US census. The Gini coefficient (raw and adjusted) indicated income inequality. Outcome measures included current symptoms of depression and alcohol dependence. Controlling for individual-level variables and state median income, the odds of depressive symptoms was not positively associated with state income inequality. Controlling for individual-level variables, state median income and alcohol distribution method, a weak negative association between Gini and alcohol dependence was observed in women, but this association disappeared after additional adjustment for beer tax. No association was observed in men. Higher state beer tax was significantly associated with lower prevalence of alcohol dependence symptoms for both men and women. The results suggest that state income inequality does not increase the experience of alcohol dependence or depression symptoms. However, evidence was found for a protective effect of increased beer taxation against alcohol dependence symptoms, suggesting the need to further consider the impact of alcohol policies on alcohol use disorders.

  7. Extension of the standard addition method by blank addition.

    PubMed

    Steliopoulos, Panagiotis

    2015-01-01

    Standard addition involves adding varying amounts of the analyte to sample portions of fixed mass or fixed volume and submitting those portions to the sample preparation procedure. After measuring the final extract solutions, the observed signals are linearly regressed on the spiked amounts. The original unknown amount is estimated by the opposite of the abscissa intercept of the fitted straight line [1]. A limitation of this method is that only data points with abscissa values equal to and greater than zero are available so that there is no information on whether linearity holds below the spiking level zero. An approach to overcome this limitation is introduced.•Standard addition is combined with blank addition.•Blank addition means that defined mixtures of blank matrix and sample material are subjected to sample preparation to give final extract solutions.•Equations are presented to estimate the original unknown amount and to calculate the 1-2α confidence interval about this estimate using the combined data set.

  8. ADDITIVITY ASSESSMENT OF TRIHALOMETHANE MIXTURES BY PROPORTIONAL RESPONSE ADDITION

    EPA Science Inventory

    If additivity is known or assumed, the toxicity of a chemical mixture may be predicted from the dose response curves of the individual chemicals comprising the mixture. As single chemical data are abundant and mixture data sparse, mixture risk methods that utilize single chemical...

  9. Extension of the standard addition method by blank addition

    PubMed Central

    Steliopoulos, Panagiotis

    2015-01-01

    Standard addition involves adding varying amounts of the analyte to sample portions of fixed mass or fixed volume and submitting those portions to the sample preparation procedure. After measuring the final extract solutions, the observed signals are linearly regressed on the spiked amounts. The original unknown amount is estimated by the opposite of the abscissa intercept of the fitted straight line [1]. A limitation of this method is that only data points with abscissa values equal to and greater than zero are available so that there is no information on whether linearity holds below the spiking level zero. An approach to overcome this limitation is introduced.•Standard addition is combined with blank addition.•Blank addition means that defined mixtures of blank matrix and sample material are subjected to sample preparation to give final extract solutions.•Equations are presented to estimate the original unknown amount and to calculate the 1-2α confidence interval about this estimate using the combined data set. PMID:26844210

  10. Saturn's variable radio period

    NASA Astrophysics Data System (ADS)

    Kurth, W. S.; Lecacheux, A.; Zarka, P.; Gurnett, D. A.; Cecconi, B.

    Temporal modulations in radio emissions are often used to determine the rotation rate of the emitting body. The rotation period (presumably) of Jupiter's interior was established in this way [Burke et al., 1962] and has recently been refined by Higgins et al. [1997]. Rotation periods for the remainder of the outer planet gas giants were determined from Voyager planetary radio astronomy observations. Similar techniques have been applied to astrophysical objects, including pulsars, for which the radio period is assumed to be the rotation period of the neutron star. In 2001, however, this simple relation between the radio period and rotation period became suspect, at least for the case of Saturn. Galopeau and Lecacheux [2001] reported that the radio period of Saturn had changed by as much as 1% from that determined by Voyager and, further, exhibited variations on time scales of years. More recently, Cassini observations indicate that the Saturn kilometric radiation is modulated with a period longer than that observed by Voyager and that this period is variable on a time scale of a year or less. The recent Higgins et al. result suggests that Jupiter's period is steady, within measurement accuracy. There are no additional measurements from Uranus or Neptune with which to look for time variations in their radio periods. For conservation of energy and angular momentum reasons, true variations of the rotation period of Saturn's deep interior are not believed to be a viable explanation for the variation in radio period, hence, it would appear that there is some disconnection of the radio period from the rotation period in the case of Saturn. One possible contributing factor may be that since Saturn's magnetic field is very accurately aligned with its rotational axis, there is no first-order beaming effect caused by the wobbling of the magnetic field, contrary to the situation at the other magnetized planets. Another explanation suggested by Galopeau and Lecacheux [2001] and

  11. Effect of climate variability on estimation of greenhouse parameters: Usefulness of a pre-instrumental temperature record

    NASA Astrophysics Data System (ADS)

    Kheshgi, Haroon S.; White, Benjamin S.

    To estimate the strength of the greenhouse warming signal embedded in the noise of natural climate variability, a statistical methodology is applied to a functional model of the signal and stochastic models of the noise. The confidence of greenhouse parameter estimates, namely climate sensitivity, obtained from a record of global near-surface temperature is highly dependent on natural climate variability with a time scale of roughly a century. A pre-instrumental temperature record is needed to construct empirically a model for natural variability of century time-scale which, in turn, is needed to determine the confidence of parameter estimates. However, for assumed models for climate variability, data prior to 1950 does not significantly improve the confidence of estimates. In fact, addition of an accurate pre-instrumental record is not expected to have a large impact on climate sensitivity estimates made with only the instrumental temperature record.

  12. [INVITED] Lasers in additive manufacturing

    NASA Astrophysics Data System (ADS)

    Pinkerton, Andrew J.

    2016-04-01

    Additive manufacturing is a topic of considerable ongoing interest, with forecasts predicting it to have major impact on industry in the future. This paper focusses on the current status and potential future development of the technology, with particular reference to the role of lasers within it. It begins by making clear the types and roles of lasers in the different categories of additive manufacturing. This is followed by concise reviews of the economic benefits and disadvantages of the technology, current state of the market and use of additive manufacturing in different industries. Details of these fields are referenced rather than expanded in detail. The paper continues, focusing on current indicators to the future of additive manufacturing. Barriers to its development, trends and opportunities in major industrial sectors, and wider opportunities for its development are covered. Evidence indicates that additive manufacturing may not become the dominant manufacturing technology in all industries, but represents an excellent opportunity for lasers to increase their influence in manufacturing as a whole.

  13. Evaluation of certain food additives.

    PubMed

    2015-01-01

    This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, including flavouring agents, and to prepare specifications for identity and purity. The first part of the report contains a general discussion of the principles governing the toxicological evaluation of and assessment of dietary exposure to food additives, including flavouring agents. A summary follows of the Committee's evaluations of technical, toxicological and dietary exposure data for eight food additives (Benzoe tonkinensis; carrageenan; citric and fatty acid esters of glycerol; gardenia yellow; lutein esters from Tagetes erecta; octenyl succinic acid-modified gum arabic; octenyl succinic acid-modified starch; paprika extract; and pectin) and eight groups of flavouring agents (aliphatic and alicyclic hydrocarbons; aliphatic and aromatic ethers; ionones and structurally related substances; miscellaneous nitrogen-containing substances; monocyclic and bicyclic secondary alcohols, ketones and related esters; phenol and phenol derivatives; phenyl-substituted aliphatic alcohols and related aldehydes and esters; and sulfur-containing heterocyclic compounds). Specifications for the following food additives were revised: citric acid; gellan gum; polyoxyethylene (20) sorbitan monostearate; potassium aluminium silicate; and Quillaia extract (Type 2). Annexed to the report are tables summarizing the Committee's recommendations for dietary exposures to and toxicological evaluations of all of the food additives and flavouring agents considered at this meeting.

  14. Evolution of solidification texture during additive manufacturing.

    PubMed

    Wei, H L; Mazumder, J; DebRoy, T

    2015-01-01

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six <100> preferred growth directions in face centered cubic alloys. Therefore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components.

  15. Evolution of solidification texture during additive manufacturing

    DOE PAGES

    Wei, H. L.; Mazumder, J.; DebRoy, T.

    2015-11-10

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six <100> preferred growth directions in face centered cubic alloys. Furthermore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numericalmore » modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components.« less

  16. The teratology testing of food additives.

    PubMed

    Barrow, Paul C; Spézia, François

    2013-01-01

    The developmental and reproductive toxicity testing (including teratogenicity) of new foods and food additives is performed worldwide according to the guidelines given in the FDA Redbook. These studies are not required for substances that are generally recognized as safe, according to the FDA inventory. The anticipated cumulated human exposure level above which developmental or reproduction studies are required depends on the structure-alert category. For food additives of concern, both developmental (prenatal) and reproduction (multigeneration) studies are required. The developmental studies are performed in two species, usually the rat and the rabbit. The reproduction study is generally performed in the rat. The two rat studies are preferably combined into a single experimental design, if possible. The test methods described in the FDA Redbook are similar to those specified by the OECD for the reproductive toxicity testing of chemicals.

  17. Evolution of solidification texture during additive manufacturing

    PubMed Central

    Wei, H. L.; Mazumder, J.; DebRoy, T.

    2015-01-01

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six <100> preferred growth directions in face centered cubic alloys. Therefore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components. PMID:26553246

  18. Evolution of solidification texture during additive manufacturing

    SciTech Connect

    Wei, H. L.; Mazumder, J.; DebRoy, T.

    2015-11-10

    Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data. Understanding and controlling texture are important because it affects mechanical and chemical properties. Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six <100> preferred growth directions in face centered cubic alloys. Furthermore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions. Here we show that numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components.

  19. The Relative Contribution of Internal and Model Variabilities to the Uncertainty in Decadal Climate Predictions

    NASA Astrophysics Data System (ADS)

    Strobach, Ehud; Bel, Golan

    2016-04-01

    distribution of the uncertainty reveals that the surface temperature has higher variability over land and at high latitudes, whereas the surface zonal wind has higher variability over the ocean. The relative importance of the internal and model variabilities depends on the averaging period, the definition of the anomaly, and the location. These findings suggest that several methods should be combined in order to assess future climate prediction uncertainties. In addition, the significant contribution of the model variability suggests that weighting of the ensemble members may reduce the uncertainties.

  20. The Intertemporal Variability of Teacher Effect Estimates

    ERIC Educational Resources Information Center

    McCaffrey, Daniel F.; Sass, Tim R.; Lockwood, J. R.; Mihaly, Kata

    2009-01-01

    The utility of value-added estimates of teachers' effects on student test scores depends on whether they can distinguish between high- and low-productivity teachers and predict future teacher performance. This article studies the year-to-year variability in value-added measures for elementary and middle school mathematics teachers from five large…