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Sample records for extremal conditional quantile

  1. Extreme Quantile Estimation in Binary Response Models

    DTIC Science & Technology

    1990-03-01

    The Spearman - Karber method and Wetherill’s w estimate only the x , while the Stochastic Approximation 4 Method of Robbins and Monro [1951] estimates...9 2 SEQUENTIAL PROCEDURES FOR EXTREME QUANTILES .................... 10 2.1 Current Methods ...using x50 is that the asymptotic variance of x1 achieves a minimum at p =.5 for the common methods used. Moreover, several Monte Carlo studies involving

  2. Estimating fish body condition with quantile regression

    USGS Publications Warehouse

    Cade, B.S.; Terrell, J.W.; Porath, M.T.

    2008-01-01

    We used quantile regression to compare the body condition of walleye Sander vitreus and white bass Morone chrysops before (1980-1988) and after (1989-2004) the establishment of alewives Alosa pseudoharengus in Lake McConaughy, Nebraska. Higher quantiles (percentiles = 100% x quantiles [0, 1]) of weight (W) at the same total length (TL) were indicative of better body condition in an allometric growth model that included separate slopes and intercepts for the before and after groups. All quantiles of walleye weights by TL increased in the years after alewife introduction, ranging from 1.01 to 1.12 times weights in the years before alewife introduction, with greatest increases for the lower (<0.50) quantiles and greater TLs. Quantiles up to 0.25 (the lowest 25th percentiles) of white bass weights were reduced in years after alewife introduction for TLs less than 300 mm, ranging from 0.78 to 0.98 times weights in the years before alewife introduction. However, quantiles greater than or equal to 0.50 (the upper 50th percentiles) of white bass weights increased for all TLs, ranging from 1.01 to 1.06 times the pre-1988 weights. A three-group analysis, which improved the model fit for longer white bass, indicated a reduction (0.80-1.0) in white bass body condition across all TLs in the first 2 years (1989-1990) after alewife introduction, whereas body condition actually improved (1.02-1.12) across all TLs in later years (1991-2004). Thus, after the establishment of alewives in 1988, walleye body condition improved for all fish at all lengths (the greatest improvement occurring among fish in poorer condition), whereas white bass body condition was initially reduced for all fish at all lengths for 2 years and improved in subsequent years. The approach that we developed for comparing fish body condition before and after a management action in Lake McConaughy could be applied to other weight-length data sets typically evaluated with relative weight indices. ?? Copyright by the

  3. Analysis of changes in extreme temperature and precipitation using quantile regression

    NASA Astrophysics Data System (ADS)

    Lee, Kyoungmi; Baek, Hee-Jeong; Cho, ChunHo

    2013-04-01

    One of the important research areas in climatology is to identify whether the long-period tendencies of change in meteorological variables appear. In the past, the analysis has been limited by the estimation of long-period trends for annual or seasonal average values on meteorological variables. However, recently, the interest in the trends regarding the whole range of values for meteorological variables, including the extreme ones, has arisen. The quantile regression is the regression analysis method for estimating the regression slopes for the values of any quantile from 0 to 1 of dependent variable distributions. This method provides a more complete picture for the conditional distribution of the dependent variable given the independent variable when both lower and upper or all quantiles are of interest. This study examines the changes in regional extreme temperature and precipitation in South Korea using quantile regression, which is applied to analyze trends, not only in the mean but in all parts of the data distribution. The results show considerable diversity across space and quantile level in South Korea. For daily temperatures in winter, the slopes in lower quantiles generally have a more distinct increase trend compared to the upper quantiles. The time series for daily minimum temperature during the winter season only shows a significant increasing trend in the lower quantile. In case of summer, most sites show an increase trend in both lower and upper quantiles for daily minimum temperature, while there are a number of sites with a decrease trend for daily maximum temperature. It was also found that the increase trend of extreme low temperature in large urban areas (0.80°C/decade) is much larger than in rural areas (0.54°C/decade) due to the effects of urbanization. Extreme climate events can have greater negative impacts on society, economy and natural environments than changes in climate means. The fast growth of population and industrialization in

  4. Regional trends in short-duration precipitation extremes: a flexible multivariate monotone quantile regression approach

    NASA Astrophysics Data System (ADS)

    Cannon, Alex

    2017-04-01

    Estimating historical trends in short-duration rainfall extremes at regional and local scales is challenging due to low signal-to-noise ratios and the limited availability of homogenized observational data. In addition to being of scientific interest, trends in rainfall extremes are of practical importance, as their presence calls into question the stationarity assumptions that underpin traditional engineering and infrastructure design practice. Even with these fundamental challenges, increasingly complex questions are being asked about time series of extremes. For instance, users may not only want to know whether or not rainfall extremes have changed over time, they may also want information on the modulation of trends by large-scale climate modes or on the nonstationarity of trends (e.g., identifying hiatus periods or periods of accelerating positive trends). Efforts have thus been devoted to the development and application of more robust and powerful statistical estimators for regional and local scale trends. While a standard nonparametric method like the regional Mann-Kendall test, which tests for the presence of monotonic trends (i.e., strictly non-decreasing or non-increasing changes), makes fewer assumptions than parametric methods and pools information from stations within a region, it is not designed to visualize detected trends, include information from covariates, or answer questions about the rate of change in trends. As a remedy, monotone quantile regression (MQR) has been developed as a nonparametric alternative that can be used to estimate a common monotonic trend in extremes at multiple stations. Quantile regression makes efficient use of data by directly estimating conditional quantiles based on information from all rainfall data in a region, i.e., without having to precompute the sample quantiles. The MQR method is also flexible and can be used to visualize and analyze the nonlinearity of the detected trend. However, it is fundamentally a

  5. Quantile Regression Technique to Investigate the Rainfall Trend for Flooding and Drought Conditions

    NASA Astrophysics Data System (ADS)

    Abbas, Salam; Xuan, Yunqing

    2017-04-01

    Climate change is a principal cause in uncertainty in quantifying future water supply, thereby complicating water resources planning and management in river basins. Climate change affects surface water resources through time-variable rainfall and air temperature. There is an increase concern of the increasing or decreasing precipitation owing to global warming. In this study, the technique of linear quantile regression is utilized to investigate rainfall trend of the extreme events (flooding and drought). This method reveals a certain advantages over the tradition linear ordinary least-square techniques for the following reasons: the error terms are not necessary to be normally distributed, does not assume homoscedastic variables (variables could be heteroscedastic), It is not sensitive to outliers, It can be used to predicts a desired quantile of the conditional distribution rather than mean and this approach is preferred when the interest is the analysis of distribution rather than average and when the main attention is the tail of distributions. The linear Quantile regression is employed in two regions: the Dee River catchment in the United Kingdom, where the daily rainfall data of 13 rain gauges were collected over the period of 1970-2004 and the Beijing metropolitan area in China for 22 rain gauges over period of 1950-2012. This technique is then conducted on the observed precipitation to examine the trend of both Flooding (represented by 95% quantile) and drought situation (5% quantile). It has been shown that the quantile regression is capable of revealing the patterns of flooding and drought without having to suffer from non-constant variance. The significance of the trend is verified using a null hypothesis for confidence levels of 95%.

  6. Estimating conditional quantiles with the help of the pinball loss

    SciTech Connect

    Steinwart, Ingo

    2008-01-01

    Using the so-called pinball loss for estimating conditional quantiles is a well-known tool in both statistics and machine learning. So far, however, only little work has been done to quantify the efficiency of this tool for non-parametric (modified) empirical risk minimization approaches. The goal of this work is to fill this gap by establishing inequalities that describe how close approximate pinball risk minimizers are to the corresponding conditional quantile. These inequalities, which hold under mild assumptions on the data-generating distribution, are then used to establish so-called variance bounds which recently turned out to play an important role in the statistical analysis of (modified) empirical risk minimization approaches. To illustrate the use of the established inequalities, we then use them to establish an oracle inequality for support vector machines that use the pinball loss. Here, it turns out that we obtain learning rates which are optimal in a min-max sense under some standard assumptions on the regularity of the conditional quantile function.

  7. Estimating the Extreme Behaviors of Students Performance Using Quantile Regression--Evidences from Taiwan

    ERIC Educational Resources Information Center

    Chen, Sheng-Tung; Kuo, Hsiao-I.; Chen, Chi-Chung

    2012-01-01

    The two-stage least squares approach together with quantile regression analysis is adopted here to estimate the educational production function. Such a methodology is able to capture the extreme behaviors of the two tails of students' performance and the estimation outcomes have important policy implications. Our empirical study is applied to the…

  8. Estimating the Extreme Behaviors of Students Performance Using Quantile Regression--Evidences from Taiwan

    ERIC Educational Resources Information Center

    Chen, Sheng-Tung; Kuo, Hsiao-I.; Chen, Chi-Chung

    2012-01-01

    The two-stage least squares approach together with quantile regression analysis is adopted here to estimate the educational production function. Such a methodology is able to capture the extreme behaviors of the two tails of students' performance and the estimation outcomes have important policy implications. Our empirical study is applied to the…

  9. Smooth conditional distribution function and quantiles under random censorship.

    PubMed

    Leconte, Eve; Poiraud-Casanova, Sandrine; Thomas-Agnan, Christine

    2002-09-01

    We consider a nonparametric random design regression model in which the response variable is possibly right censored. The aim of this paper is to estimate the conditional distribution function and the conditional alpha-quantile of the response variable. We restrict attention to the case where the response variable as well as the explanatory variable are unidimensional and continuous. We propose and discuss two classes of estimators which are smooth with respect to the response variable as well as to the covariate. Some simulations demonstrate that the new methods have better mean square error performances than the generalized Kaplan-Meier estimator introduced by Beran (1981) and considered in the literature by Dabrowska (1989, 1992) and Gonzalez-Manteiga and Cadarso-Suarez (1994).

  10. Areal rainfall construction and estimation of extreme quantiles.

    NASA Astrophysics Data System (ADS)

    Penot, David; Paquet, Emmanuel; Lang, Michel

    2014-05-01

    Areal rainfall estimation and extrapolation to extremes is a key issue for catchment flood study. It is a tricky problem which deals with spatial interpolation (to build an estimate at the catchment's scale based on few rain gauges only), and probabilistic extrapolation (for extreme values estimation). In this study, several methods to build an areal rainfall estimation are compared. The first method is the commonly used Thiessen polygons. A second way to build an areal rainfall relies on the SPAZM method [Gottardi, 2012], in which daily rain fields are reconstructed at a 1km2 resolution, with an interpolation scheme integrating the altitude of the pixel and the weather type of the day. These two methods are compared to the stochastic rain field simulator SAMPO [Leblois et Creutin, 2013], which is an adaptation of the turning band method allowing to generate over 50 years of realistic rain fields. Several questions are tackled in this study: In a Thiessen estimation, how many rain gauges should be selected ? Which weighting scheme should be used ? SPAZM is an interpolator designed to produce unbiased mean annual precipitation (MAP) at a catchment's scale. So if a Thiessen areal rainfall is scaled to fit the MAP given by SPAZM, how does it affect its extreme rainfall estimation ? If a virtual rain gauges network is extracted from the rain fields generated by SAMPO, how do behave the Thiessen and SPAZM areal rainfall estimations based on these point values ? At the end, some abatement functions are obtained, showing the influence of the catchment's area and the options chosen to build the areal rainfall estimations. References: F. Gottardi, C. Obled, J. Gailhard, and E. Paquet, Statistical reanalysis of precipitation fields based on ground network data and weather patterns : Application over french mountains. Journal of Hydrology, 432-433:154 - 167, 2012. ISSN 0022-1694. E. Leblois and J-D. Creutin, Space-time simulation of intermittent rainfall with prescribed

  11. Sensitivity of extreme flood quantile estimation to rainfall-runoff modeling

    NASA Astrophysics Data System (ADS)

    Mathevet, T.; Garavaglia, F.; Paquet, E.; Garçon, R.

    2012-04-01

    EDF (Électricité de France) design floods of dam spillways are now computed using a probabilistic method named SCHADEX (Climatic-hydrological simulation of extreme foods (Paquet et al., 2006, Garavaglia et al., 2009, 2010). This method aims at estimating extreme flood quantiles by the combination of a weather pattern based rainfall probabilistic model and a conceptual rainfall-runoff model. Extreme floods quantiles are estimated through a runoff generation process that combines a stochastic generation of rainfall events and a semi-continuous rainfall-runoff simulation. The aim of this paper is to investigate the sensitivity of extreme flood quantile estimation to the rainfall-runoff model (structure, parameters) used in the simulation framework. To explore this topic we have used two rainfall-runoff models (i.e. MORDOR model (Garçon et al., 1996) and GR4J model (Andreassian et al., 2006)) with four different objective functions (based on Nash-Sutcliffe and Kling-Gupta efficiencies) and a classical split-sample scheme. This testing strategy has been applied to calibrate models on a set of 30 French watersheds at different time-steps (mainly daily and 4 to 12 hours). When calibrated, models were used within the SCHADEX method and flood quantiles were evaluated at different return levels in interpolation and extrapolation (10, 100, 1000 years return-period). The main result of this comparative study is that extreme flood quantile estimations are more sensitive to (i) the objective function used and (ii) the time series length and period used for model calibration then (iii) the rainfall-runoff structure. Within this comparative study, the mean variability on a 1000 years return-period is up to 20%. Another interesting result is that, for a same objective function and time series period, the influence of the rainfall-runoff model is relatively moderated in extrapolation domain because the two rainfall-runoff models converged towards their asymptotic behaviours, but

  12. HIGHLIGHTING DIFFERENCES BETWEEN CONDITIONAL AND UNCONDITIONAL QUANTILE REGRESSION APPROACHES THROUGH AN APPLICATION TO ASSESS MEDICATION ADHERENCE

    PubMed Central

    BORAH, BIJAN J.; BASU, ANIRBAN

    2014-01-01

    The quantile regression (QR) framework provides a pragmatic approach in understanding the differential impacts of covariates along the distribution of an outcome. However, the QR framework that has pervaded the applied economics literature is based on the conditional quantile regression method. It is used to assess the impact of a covariate on a quantile of the outcome conditional on specific values of other covariates. In most cases, conditional quantile regression may generate results that are often not generalizable or interpretable in a policy or population context. In contrast, the unconditional quantile regression method provides more interpretable results as it marginalizes the effect over the distributions of other covariates in the model. In this paper, the differences between these two regression frameworks are highlighted, both conceptually and econometrically. Additionally, using real-world claims data from a large US health insurer, alternative QR frameworks are implemented to assess the differential impacts of covariates along the distribution of medication adherence among elderly patients with Alzheimer’s disease. PMID:23616446

  13. Highlighting differences between conditional and unconditional quantile regression approaches through an application to assess medication adherence.

    PubMed

    Borah, Bijan J; Basu, Anirban

    2013-09-01

    The quantile regression (QR) framework provides a pragmatic approach in understanding the differential impacts of covariates along the distribution of an outcome. However, the QR framework that has pervaded the applied economics literature is based on the conditional quantile regression method. It is used to assess the impact of a covariate on a quantile of the outcome conditional on specific values of other covariates. In most cases, conditional quantile regression may generate results that are often not generalizable or interpretable in a policy or population context. In contrast, the unconditional quantile regression method provides more interpretable results as it marginalizes the effect over the distributions of other covariates in the model. In this paper, the differences between these two regression frameworks are highlighted, both conceptually and econometrically. Additionally, using real-world claims data from a large US health insurer, alternative QR frameworks are implemented to assess the differential impacts of covariates along the distribution of medication adherence among elderly patients with Alzheimer's disease. Copyright © 2013 John Wiley & Sons, Ltd.

  14. Anticipating Future Extreme Climate Events for Alaska Using Dynamical Downscaling and Quantile Mapping

    NASA Astrophysics Data System (ADS)

    Lader, R.; Walsh, J. E.

    2016-12-01

    Alaska is projected to experience major changes in extreme climate during the 21st century, due to greenhouse warming and exacerbated by polar amplification, wherein the Arctic is warming at twice the rate compared to the Northern Hemisphere. Given its complex topography, Alaska displays extreme gradients of temperature and precipitation. However, global climate models (GCMs), which typically have a spatial resolution on the order of 100km, struggle to replicate these extremes. To help resolve this issue, this study employs dynamically downscaled regional climate simulations and quantile-mapping methodologies to provide a full suite of daily model variables at 20 km spatial resolution for Alaska, from 1970 to 2100. These data include downscaled products of the: ERA-Interim reanalysis from 1979 to 2015, GFDL-CM3 historical from 1970 to 2005, and GFDL-CM3 RCP 8.5 from 2006 to 2100. Due to the limited nature of long-term observations and high-resolution modeling in Alaska, these data enable a broad expansion of extremes analysis. This study uses these data to highlight a subset of the 27 climate extremes indices, previously defined by the Expert Team on Climate Change Detection and Indices, as they pertain to climate change in Alaska. These indices are based on the statistical distributions of daily surface temperature and precipitation and focus on threshold exceedance, and percentiles. For example, the annual number of days with a daily maximum temperature greater than 25°C is anticipated to triple in many locations in Alaska by the end of the century. Climate extremes can also refer to long duration events, such as the record-setting warmth that defined the 2015-16 cold season in Alaska. The downscaled climate model simulations indicate that this past winter will be considered normal by as early as the mid-2040s, if we continue to warm according to the business-as-usual RCP 8.5 emissions scenario. This represents an accelerated warming as compared to projections

  15. Study on quantile estimates of extreme precipitation and their spatiotemporal consistency adjustment over the Huaihe River basin

    NASA Astrophysics Data System (ADS)

    Shao, Yuehong; Wu, Junmei; Li, Min

    2017-01-01

    The quantile estimates and spatiotemporal consistency of extreme precipitation are studied by regional linear frequency analysis for Huaihe River basin in China. Firstly, the study area can be categorized into six homogeneous regions by using cluster analysis, heterogeneity measure, and discordancy measure. In the next step, we determine the optimum distribution for each homogeneous region by using two criteria of Monte Carlo simulations and the root-mean-square error (RMSE) of the sample L-moments. A diagram of L-moments ratio is used to further judge and validate the optimum distribution. The generalized extreme value (GEV), generalized normal (GNO), and generalized logistic (GLO) for 24-h duration are determined to be the more appropriate distribution based on the two criteria, L-moments ratio plot, and the tail thickness of curve in adjacent regions. A summary assessment can provide the more reasonable distribution, which avoids arbitrary results from single test. An important practical element of this study that was missing from previous works is the quantile spatiotemporal consistency analysis, which helps identify non-monotonicity among quantiles at different durations and reduces the gradient of estimates in the adjacent regions. Abnormality and spatial discontinuation can be removed by distributing the surplus of the ratio and twice different interpolation. A complete set of spatiotemporal consistent quantile estimates for various duration (24 h, 3 days, 5 days, and 7 days) and return periods (from 2 to 1000 years) can be obtained by using the abovementioned method in the study area, which are in the agreement with the observed precipitation extremes. It will provide important basis for hydrometeorological research, which is of significant scientific and practical merit.

  16. On the prediction of extreme flood quantiles at ungauged locations with spatial copula

    NASA Astrophysics Data System (ADS)

    Durocher, Martin; Chebana, Fateh; Ouarda, Taha B. M. J.

    2016-02-01

    The present study investigates the use of the spatial copula approach for predicting flood quantiles at ungauged basins. Spatial copulas are the formalization of traditional geostatistics by copulas. In regional flood frequency analysis (RFFA), the regression of flood quantiles is often carried out at the logarithmic scale. Consequently, traditional interpolation methods introduce a bias and provide suboptimal predictions. In this study, the copula framework is examined for offering proper corrections in this framework. Moreover, copula techniques separate the regional distribution of flood quantiles from spatial dependence. This provides a full probabilistic model that represents a more flexible framework where proper combinations of regional distribution and dependence can be adapted to various situations that are encountered in RFFA. The adequacy of the investigated methodology is evaluated on a real world case study involving hydrometric stations from southern Quebec, Canada. Results show that the spatial copula framework is able to deal with the problem of bias, is robust to the presence of problematic stations and may improve the quality of quantile predictions while reducing the level of complexity of the models used in RFFA.

  17. Improving Global Forecast System of extreme precipitation events with regional statistical model: Application of quantile-based probabilistic forecasts

    NASA Astrophysics Data System (ADS)

    Shastri, Hiteshri; Ghosh, Subimal; Karmakar, Subhankar

    2017-02-01

    Forecasting of extreme precipitation events at a regional scale is of high importance due to their severe impacts on society. The impacts are stronger in urban regions due to high flood potential as well high population density leading to high vulnerability. Although significant scientific improvements took place in the global models for weather forecasting, they are still not adequate at a regional scale (e.g., for an urban region) with high false alarms and low detection. There has been a need to improve the weather forecast skill at a local scale with probabilistic outcome. Here we develop a methodology with quantile regression, where the reliably simulated variables from Global Forecast System are used as predictors and different quantiles of rainfall are generated corresponding to that set of predictors. We apply this method to a flood-prone coastal city of India, Mumbai, which has experienced severe floods in recent years. We find significant improvements in the forecast with high detection and skill scores. We apply the methodology to 10 ensemble members of Global Ensemble Forecast System and find a reduction in ensemble uncertainty of precipitation across realizations with respect to that of original precipitation forecasts. We validate our model for the monsoon season of 2006 and 2007, which are independent of the training/calibration data set used in the study. We find promising results and emphasize to implement such data-driven methods for a better probabilistic forecast at an urban scale primarily for an early flood warning.

  18. Estimating geographic variation on allometric growth and body condition of Blue Suckers with quantile regression

    USGS Publications Warehouse

    Cade, B.S.; Terrell, J.W.; Neely, B.C.

    2011-01-01

    Increasing our understanding of how environmental factors affect fish body condition and improving its utility as a metric of aquatic system health require reliable estimates of spatial variation in condition (weight at length). We used three statistical approaches that varied in how they accounted for heterogeneity in allometric growth to estimate differences in body condition of blue suckers Cycleptus elongatus across 19 large-river locations in the central USA. Quantile regression of an expanded allometric growth model provided the most comprehensive estimates, including variation in exponents within and among locations (range = 2.88–4.24). Blue suckers from more-southerly locations had the largest exponents. Mixed-effects mean regression of a similar expanded allometric growth model allowed exponents to vary among locations (range = 3.03–3.60). Mean relative weights compared across selected intervals of total length (TL = 510–594 and 594–692 mm) in a multiplicative model involved the implicit assumption that allometric exponents within and among locations were similar to the exponent (3.46) for the standard weight equation. Proportionate differences in the quantiles of weight at length for adult blue suckers (TL = 510, 594, 644, and 692 mm) compared with their average across locations ranged from 1.08 to 1.30 for southern locations (Texas, Mississippi) and from 0.84 to 1.00 for northern locations (Montana, North Dakota); proportionate differences for mean weight ranged from 1.13 to 1.17 and from 0.87 to 0.95, respectively, and those for mean relative weight ranged from 1.10 to 1.18 and from 0.86 to 0.98, respectively. Weights for fish at longer lengths varied by 600–700 g within a location and by as much as 2,000 g among southern and northern locations. Estimates for the Wabash River, Indiana (0.96–1.07 times the average; greatest increases for lower weights at shorter TLs), and for the Missouri River from Blair, Nebraska, to Sioux City, Iowa (0.90

  19. Mineralogy under extreme conditions

    SciTech Connect

    Shu, Jinfu

    2012-02-07

    We have performed measurements of minerals based on the synchrotron source for single crystal and powder X-ray diffraction, inelastic scattering, spectroscopy and radiography by using diamond anvil cells. We investigated the properties of iron (Fe), iron-magnesium oxides (Fe, Mg)O, silica(SiO{sub 2}), iron-magnesium silicates (Fe, Mg)SiO{sub 3} under simulated high pressure-high temperature extreme conditions of the Earth's crust, upper mantle, low mantle, core-mantle boundary, outer core, and inner core. The results provide a new window on the investigation of the mineral properties at Earth's conditions.

  20. A Methodology for Robust Multiproxy Paleoclimate Reconstructions and Modeling of Temperature Conditional Quantiles.

    PubMed

    Janson, Lucas; Rajaratnam, Bala

    Great strides have been made in the field of reconstructing past temperatures based on models relating temperature to temperature-sensitive paleoclimate proxies. One of the goals of such reconstructions is to assess if current climate is anomalous in a millennial context. These regression based approaches model the conditional mean of the temperature distribution as a function of paleoclimate proxies (or vice versa). Some of the recent focus in the area has considered methods which help reduce the uncertainty inherent in such statistical paleoclimate reconstructions, with the ultimate goal of improving the confidence that can be attached to such endeavors. A second important scientific focus in the subject area is the area of forward models for proxies, the goal of which is to understand the way paleoclimate proxies are driven by temperature and other environmental variables. One of the primary contributions of this paper is novel statistical methodology for (1) quantile regression with autoregressive residual structure, (2) estimation of corresponding model parameters, (3) development of a rigorous framework for specifying uncertainty estimates of quantities of interest, yielding (4) statistical byproducts that address the two scientific foci discussed above. We show that by using the above statistical methodology we can demonstrably produce a more robust reconstruction than is possible by using conditional-mean-fitting methods. Our reconstruction shares some of the common features of past reconstructions, but we also gain useful insights. More importantly, we are able to demonstrate a significantly smaller uncertainty than that from previous regression methods. In addition, the quantile regression component allows us to model, in a more complete and flexible way than least squares, the conditional distribution of temperature given proxies. This relationship can be used to inform forward models relating how proxies are driven by temperature.

  1. A Methodology for Robust Multiproxy Paleoclimate Reconstructions and Modeling of Temperature Conditional Quantiles

    PubMed Central

    Janson, Lucas; Rajaratnam, Bala

    2014-01-01

    Great strides have been made in the field of reconstructing past temperatures based on models relating temperature to temperature-sensitive paleoclimate proxies. One of the goals of such reconstructions is to assess if current climate is anomalous in a millennial context. These regression based approaches model the conditional mean of the temperature distribution as a function of paleoclimate proxies (or vice versa). Some of the recent focus in the area has considered methods which help reduce the uncertainty inherent in such statistical paleoclimate reconstructions, with the ultimate goal of improving the confidence that can be attached to such endeavors. A second important scientific focus in the subject area is the area of forward models for proxies, the goal of which is to understand the way paleoclimate proxies are driven by temperature and other environmental variables. One of the primary contributions of this paper is novel statistical methodology for (1) quantile regression with autoregressive residual structure, (2) estimation of corresponding model parameters, (3) development of a rigorous framework for specifying uncertainty estimates of quantities of interest, yielding (4) statistical byproducts that address the two scientific foci discussed above. We show that by using the above statistical methodology we can demonstrably produce a more robust reconstruction than is possible by using conditional-mean-fitting methods. Our reconstruction shares some of the common features of past reconstructions, but we also gain useful insights. More importantly, we are able to demonstrate a significantly smaller uncertainty than that from previous regression methods. In addition, the quantile regression component allows us to model, in a more complete and flexible way than least squares, the conditional distribution of temperature given proxies. This relationship can be used to inform forward models relating how proxies are driven by temperature. PMID:25587203

  2. Maximum likelihood estimation of the parameters and quantiles of the general extreme-value distribution from censored samples

    NASA Astrophysics Data System (ADS)

    Phien, Huynh Ngoc; Fang, Tsu-Shang Emma

    1989-01-01

    The General Extreme Value (GEV) distribution has become increasingly popular, as has the use of historic information, in flood frequency analysis during recent years. Both call for a systematic investigation of the properties of the maximum likelihood (ML) estimators obtained from censored samples. In this study, such an investigation was made for the type-1 censoring believed to be more frequently encountered in practical situations. All the mathematical equations needed for obtaining the ML estimators of the parameters and the quantiles (represented by the T- year event) were derived and Monte Carlo experiments were carried out to determine their sampling properties. It was found that censoring may reduce the bias of the parameter estimators but does not necessarily increase the variances. It was also found that the variances-covariances of the parameter estimators, and hence the variance of the T- year event, are better approximated by using the observed rather than the Fisher information matrix.

  3. (Welding under extreme conditions)

    SciTech Connect

    Davis, S.A.

    1989-09-29

    The traveler was an invited member of the United States delegation and representative of the Basic Energy Science Welding Science program at the 42nd Annual International Institute of Welding (IIW) Assembly and Conference held in Helsinki, Finland. The conference and the assembly was attended by about 600 delegates representing 40 countries. The theme of the conference was welding under extreme conditions. The conference program contained several topics related to welding in nuclear, arctic petrochemical, underwater, hyperbaric and space environments. At the annual assembly the traveler was a delegate (US) to two working groups of the IIW, namely Commission IX and welding research study group 212. Following the conference the traveler visited the Danish Welding Institute in Copenhagen and the Risoe National Laboratory in Roskilde. Prior to the conference the traveler visited Lappeenranta University of Technology and presented an invited seminar entitled Recent Advances in Welding Science and Technology.''

  4. Quantile regression for climate data

    NASA Astrophysics Data System (ADS)

    Marasinghe, Dilhani Shalika

    Quantile regression is a developing statistical tool which is used to explain the relationship between response and predictor variables. This thesis describes two examples of climatology using quantile regression.Our main goal is to estimate derivatives of a conditional mean and/or conditional quantile function. We introduce a method to handle autocorrelation in the framework of quantile regression and used it with the temperature data. Also we explain some properties of the tornado data which is non-normally distributed. Even though quantile regression provides a more comprehensive view, when talking about residuals with the normality and the constant variance assumption, we would prefer least square regression for our temperature analysis. When dealing with the non-normality and non constant variance assumption, quantile regression is a better candidate for the estimation of the derivative.

  5. Detectors in Extreme Conditions

    SciTech Connect

    Blaj, G.; Carini, G.; Carron, S.; Haller, G.; Hart, P.; Hasi, J.; Herrmann, S.; Kenney, C.; Segal, J.; Tomada, A.

    2015-08-06

    Free Electron Lasers opened a new window on imaging the motion of atoms and molecules. At SLAC, FEL experiments are performed at LCLS using 120Hz pulses with 1012 - 1013 photons in 10 femtoseconds (billions of times brighter than the most powerful synchrotrons). This extreme detection environment raises unique challenges, from obvious to surprising. Radiation damage is a constant threat due to accidental exposure to insufficiently attenuated beam, focused beam and formation of ice crystals reflecting the beam onto the detector. Often high power optical lasers are also used (e.g., 25TW), increasing the risk of damage or impeding data acquisition through electromagnetic pulses (EMP). The sample can contaminate the detector surface or even produce shrapnel damage. Some experiments require ultra high vacuum (UHV) with strict design, surface contamination and cooling requirements - also for detectors. The setup is often changed between or during experiments with short turnaround times, risking mechanical and ESD damage, requiring work planning, training of operators and sometimes continuous participation of the LCLS Detector Group in the experiments. The detectors used most often at LCLS are CSPAD cameras for hard x-rays and pnCCDs for soft x-rays.

  6. Survival in Extreme Conditions.

    ERIC Educational Resources Information Center

    Bloom, Martin; Halsema, James

    1983-01-01

    Explores the psychosocial and environmental configurations involved in the survival of 500 civilians in a Japanese internment camp in the Philippines during World War II. Although conditions were very harsh, the survival rate of this group was better than expected. Discusses available demographic, social organizational, and cultural information.…

  7. Survival in Extreme Conditions.

    ERIC Educational Resources Information Center

    Bloom, Martin; Halsema, James

    1983-01-01

    Explores the psychosocial and environmental configurations involved in the survival of 500 civilians in a Japanese internment camp in the Philippines during World War II. Although conditions were very harsh, the survival rate of this group was better than expected. Discusses available demographic, social organizational, and cultural information.…

  8. An Investigation of Quantile Function Estimators Relative to Quantile Confidence Interval Coverage.

    PubMed

    Wei, Lai; Wang, Dongliang; Hutson, Alan D

    In this article, we investigate the limitations of traditional quantile function estimators and introduce a new class of quantile function estimators, namely, the semi-parametric tail-extrapolated quantile estimators, which has excellent performance for estimating the extreme tails with finite sample sizes. The smoothed bootstrap and direct density estimation via the characteristic function methods are developed for the estimation of confidence intervals. Through a comprehensive simulation study to compare the confidence interval estimations of various quantile estimators, we discuss the preferred quantile estimator in conjunction with the confidence interval estimation method to use under different circumstances. Data examples are given to illustrate the superiority of the semi-parametric tail-extrapolated quantile estimators. The new class of quantile estimators is obtained by slight modification of traditional quantile estimators, and therefore, should be specifically appealing to researchers in estimating the extreme tails.

  9. Extreme Conditions Modeling Workshop Report

    SciTech Connect

    Coe, R. G.; Neary, V. S.; Lawson, M. J.; Yu, Y.; Weber, J.

    2014-07-01

    Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL) hosted the Wave Energy Converter (WEC) Extreme Conditions Modeling (ECM) Workshop in Albuquerque, NM on May 13th-14th, 2014. The objective of the workshop was to review the current state of knowledge on how to model WECs in extreme conditions (e.g. hurricanes and other large storms) and to suggest how U.S. Department of Energy (DOE) and national laboratory resources could be used to improve ECM methods for the benefit of the wave energy industry.

  10. How Cells Endure Extreme Conditions

    SciTech Connect

    2009-01-01

    One of natures most gripping feats of survival is now better understood. For the first time, Berkeley Lab scientists observed the chemical changes in individual cells that enable them to survive in conditions that should kill them. http://newscenter.lbl.gov/feature-stories/2009/07/07/cells-endure-extremes/

  11. Extreme Conditions Modeling Workshop Report

    SciTech Connect

    Coe, Ryan Geoffrey; Neary, Vincent Sinclair; Lawon, Michael J.; Yu, Yi-Hsiang; Weber, Jochem

    2014-07-01

    Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL) hosted the Wave Energy Converter (WEC) Extreme Conditions Modeling (ECM) Workshop in Albuquerque, New Mexico on May 13–14, 2014. The objective of the workshop was to review the current state of knowledge on how to numerically and experimentally model WECs in extreme conditions (e.g. large ocean storms) and to suggest how national laboratory resources could be used to improve ECM methods for the benefit of the wave energy industry. More than 30 U.S. and European WEC experts from industry, academia, and national research institutes attended the workshop, which consisted of presentations from W EC developers, invited keynote presentations from subject matter experts, breakout sessions, and a final plenary session .

  12. Can Quantile Mapping be Used for Downscaling?

    NASA Astrophysics Data System (ADS)

    Maraun, Douglas

    2013-04-01

    Quantile mapping is routinely applied to correct biases of regional climate model simulations compared to observational data. If the observations are of similar resolution as the regional climate model, quantile mapping is a feasible approach. But if the observations are of much higher resolution, quantile mapping also attempts to bridge this scale mismatch. Here I show for daily precipitation, that such quantile mapping based downscaling is not feasible but introduces similar problems as inflation of perfect prog downscaling: the spatial and temporal structure of the corrected time series is misrepresented, the drizzle effect for area means is over-corrected, area mean extremes are over-estimated and trends are affected. To overcome these problems, stochastic bias correction is required. D Maraun, Bias Correction, Quantile Mapping and Downscaling. Revisiting the Inflation Issue. J Climate, in press, 2013

  13. Parametric modeling of quantile regression coefficient functions.

    PubMed

    Frumento, Paolo; Bottai, Matteo

    2016-03-01

    Estimating the conditional quantiles of outcome variables of interest is frequent in many research areas, and quantile regression is foremost among the utilized methods. The coefficients of a quantile regression model depend on the order of the quantile being estimated. For example, the coefficients for the median are generally different from those of the 10th centile. In this article, we describe an approach to modeling the regression coefficients as parametric functions of the order of the quantile. This approach may have advantages in terms of parsimony, efficiency, and may expand the potential of statistical modeling. Goodness-of-fit measures and testing procedures are discussed, and the results of a simulation study are presented. We apply the method to analyze the data that motivated this work. The described method is implemented in the qrcm R package.

  14. Materials Response under extreme conditions

    SciTech Connect

    Remington, B A; Lorenz, K T; Pollaine, S; McNaney, J M

    2005-10-06

    Solid state experiments at extreme pressures, 10-100 GPa (0.1-1 Mbar) and strain rates (10{sup 6}-10{sup 8} s{sup -1}) are being developed on high-energy laser facilities. The goal is an experimental capability to test constitutive models for high-pressure, solid-state strength for a variety of materials. Relevant constitutive models are discussed, and our progress in developing a quasi-isentropic, ramped-pressure, shockless drive is given. Designs to test the constitutive models with experiments measuring perturbation growth due to the Rayleigh-Taylor instability in solid-state samples are presented.

  15. Complex Plasma Research Under Extreme Conditions

    SciTech Connect

    Ishihara, Osamu

    2008-09-07

    Complex plasma research under extreme conditions is described. The extreme conditions include low-dimensionality for self-organized structures of dust particles, dust magnetization in high magnetic field, criticality in phase transition, and cryogenic environment for Coulomb crystals and dust dynamics.

  16. Raman spectroscopy under extreme conditions

    SciTech Connect

    Goncharov, A F; Crowhurst, J C

    2004-11-05

    We report the results of Raman measurements of various materials under simultaneous conditions of high temperature and high pressure in the diamond anvil cell (DAC). High temperatures are generated by laser heating or internal resistive (ohmic) heating or a combination of both. We present Raman spectra of cubic boron nitride (cBN) to 40 GPa and up to 2300 K that show a continuous pressure and temperature shift of the frequency of the transverse optical mode. We have also obtained high-pressure Raman spectra from a new noble metal nitride, which we synthesized at approximately 50 GPa and 2000 K. We have obtained high-temperature spectra from pure nitrogen to 39 GPa and up to 2000 K, which show the presence of a hot band that has previously been observed in CARS measurements. These measurements have also allowed us to constrain the melting curve and to examine changes in the intramolecular potential with pressure.

  17. Regularized Quantile Regression and Robust Feature Screening for Single Index Models

    PubMed Central

    Zhong, Wei; Zhu, Liping; Li, Runze; Cui, Hengjian

    2015-01-01

    We propose both a penalized quantile regression and an independence screening procedure to identify important covariates and to exclude unimportant ones for a general class of ultrahigh dimensional single-index models, in which the conditional distribution of the response depends on the covariates via a single-index structure. We observe that the linear quantile regression yields a consistent estimator of the direction of the index parameter in the single-index model. Such an observation dramatically reduces computational complexity in selecting important covariates in the single-index model. We establish an oracle property for the penalized quantile regression estimator when the covariate dimension increases at an exponential rate of the sample size. From a practical perspective, however, when the covariate dimension is extremely large, the penalized quantile regression may suffer from at least two drawbacks: computational expediency and algorithmic stability. To address these issues, we propose an independence screening procedure which is robust to model misspecification, and has reliable performance when the distribution of the response variable is heavily tailed or response realizations contain extreme values. The new independence screening procedure offers a useful complement to the penalized quantile regression since it helps to reduce the covariate dimension from ultrahigh dimensionality to a moderate scale. Based on the reduced model, the penalized linear quantile regression further refines selection of important covariates at different quantile levels. We examine the finite sample performance of the newly proposed procedure by Monte Carlo simulations and demonstrate the proposed methodology by an empirical analysis of a real data set. PMID:26941542

  18. Efficient Regressions via Optimally Combining Quantile Information*

    PubMed Central

    Zhao, Zhibiao; Xiao, Zhijie

    2014-01-01

    We develop a generally applicable framework for constructing efficient estimators of regression models via quantile regressions. The proposed method is based on optimally combining information over multiple quantiles and can be applied to a broad range of parametric and nonparametric settings. When combining information over a fixed number of quantiles, we derive an upper bound on the distance between the efficiency of the proposed estimator and the Fisher information. As the number of quantiles increases, this upper bound decreases and the asymptotic variance of the proposed estimator approaches the Cramér-Rao lower bound under appropriate conditions. In the case of non-regular statistical estimation, the proposed estimator leads to super-efficient estimation. We illustrate the proposed method for several widely used regression models. Both asymptotic theory and Monte Carlo experiments show the superior performance over existing methods. PMID:25484481

  19. Quantiles Regression Approach to Identifying the Determinant of Breastfeeding Duration

    NASA Astrophysics Data System (ADS)

    Mahdiyah; Norsiah Mohamed, Wan; Ibrahim, Kamarulzaman

    In this study, quantiles regression approach is applied to the data of Malaysian Family Life Survey (MFLS), to identify factors which are significantly related to the different conditional quantiles of the breastfeeding duration. It is known that the classical linear regression methods are based on minimizing residual sum of squared, but quantiles regression use a mechanism which are based on the conditional median function and the full range of other conditional quantile functions. Overall, it is found that the period of breastfeeding is significantly related to place of living, religion and total number of children in the family.

  20. Conditional simulations for fields of extreme precipitation

    NASA Astrophysics Data System (ADS)

    Bechler, Aurélien; Vrac, Mathieu; Bel, Liliane

    2014-05-01

    Many environmental models, such as hydrological models, require input data, e.g. precipitation values, correctly simulated and distributed, even at locations where no observation is available. This is particularly true for extreme events that may be of high importance for impact studies. The last decade has seen max-stable processes emerge as a powerful tool for the statistical modeling of spatial extremes. Recently, such processes have been used in climate context to perform simulations at ungauged sites based on empirical distributions of a spatial field conditioned by observed values in some locations. In this work conditional simulations of extremal t process are investigated, taking benefits of its spectral construction. The methodology of conditional simulations proposed by Dombry et al. [2013] for Brown-Resnick and Schlather models is adapted for the extremal t process with some improvements which enlarge the possible number of conditional points. A simulation study enables to highlight the role of the different parameters of the model and to emphasize the importance of the steps of the algorithm. In this work, we focus on the French Mediterranean basin, which is a key spot of occurrences of meteorological extremes such as heavy precipitation. Indeed, major extreme precipitation are regularly observed in this region near the 'cévenol" mountains. The modeling and the understanding of these extreme precipitation - the so-called 'cévenol events" - are of major importance for hydrological studies in this complex terrain since they often trigger major floods in this region. The application of our methodology on real data in this region shows that the model and the algorithm perform well provided the stationary assumptions are fulfilled.

  1. Quantile Estimation in Dependent Sequences.

    DTIC Science & Technology

    1981-09-01

    Heidelberger and Welch (1980; 1981) we used K = 25 and d = 2 , although for extreme quantiles in highly congested queues with short run lengths, d = 3 was...YqG , i.e. if Yq(1) i "’" <q(G) are the order statistics of Yql,...,qG 23 1.L then the ngm is defiried by (assuming G is odd) (3.8) ngq(xp) = yq([. 5G ...random variables (NEAR(l) and GNEAR(1) processes; see Lawrance and Lewis (1981a) and (1981b)) and on waiting time se- quences in heavily congested

  2. Non-crossing weighted kernel quantile regression with right censored data.

    PubMed

    Bang, Sungwan; Eo, Soo-Heang; Cho, Yong Mee; Jhun, Myoungshic; Cho, HyungJun

    2016-01-01

    Regarding survival data analysis in regression modeling, multiple conditional quantiles are useful summary statistics to assess covariate effects on survival times. In this study, we consider an estimation problem of multiple nonlinear quantile functions with right censored survival data. To account for censoring in estimating a nonlinear quantile function, weighted kernel quantile regression (WKQR) has been developed by using the kernel trick and inverse-censoring-probability weights. However, the individually estimated quantile functions based on the WKQR often cross each other and consequently violate the basic properties of quantiles. To avoid this problem of quantile crossing, we propose the non-crossing weighted kernel quantile regression (NWKQR), which estimates multiple nonlinear conditional quantile functions simultaneously by enforcing the non-crossing constraints on kernel coefficients. The numerical results are presented to demonstrate the competitive performance of the proposed NWKQR over the WKQR.

  3. Interquantile Shrinkage and Variable Selection in Quantile Regression

    PubMed Central

    Jiang, Liewen; Bondell, Howard D.; Wang, Huixia Judy

    2014-01-01

    Examination of multiple conditional quantile functions provides a comprehensive view of the relationship between the response and covariates. In situations where quantile slope coefficients share some common features, estimation efficiency and model interpretability can be improved by utilizing such commonality across quantiles. Furthermore, elimination of irrelevant predictors will also aid in estimation and interpretation. These motivations lead to the development of two penalization methods, which can identify the interquantile commonality and nonzero quantile coefficients simultaneously. The developed methods are based on a fused penalty that encourages sparsity of both quantile coefficients and interquantile slope differences. The oracle properties of the proposed penalization methods are established. Through numerical investigations, it is demonstrated that the proposed methods lead to simpler model structure and higher estimation efficiency than the traditional quantile regression estimation. PMID:24653545

  4. The quantile score and its decomposition

    NASA Astrophysics Data System (ADS)

    Bentzien, Sabrina; Friederichs, Petra

    2014-05-01

    Forecast verification for probabilistic weather and climate predictions gain more and more importance due to the increasing number of ensemble prediction systems. The predictive performance of probabilistic forecasts is generally assessed using proper score functions, which are applied to a set of forecast-observation pairs. The propriety of a score guarantees honesty and prevents hedging. A variety of proper scores exist for different types of probabilistic forecasts. Moreover, proper scoring functions can be decomposed into the three parts reliability, resolution, and uncertainty, which describe main characteristics of a forecasting scheme. This decomposition is well known for the Brier score and the continuous ranked probability score. This study expands the pool of verification methods for probabilistic forecasts by a decomposition of the quantile score (QS). Quantiles are suitable probabilistic measures especially for extreme forecast events, since they do not depend on an apriori defined threshold. The QS is a weighted absolute error between quantile forecasts and observations. We derive a decomposition of the QS in reliability, resolution, and uncertainty, and give a brief description of potential biases. A quantile reliability plot is presented. The quantile verification within this framework is illustrated on precipitation forecasts derived from the mesoscale ensemble prediction system COSMO-DE-EPS of the German Meteorological Service.

  5. Meteorological conditions for extreme crop yield seasons

    NASA Astrophysics Data System (ADS)

    van der Wiel, Karin; Selten, Frank; Bintanja, Richard

    2017-04-01

    Year-to-year variability in crop yield causes large variability in yearly total crop production. This variability in production causes uncertainty in farmers' income and destabilisation of food supply and food security world wide. We use a large model ensemble generated using the global climate model EC-Earth to characterise the meteorological conditions of highest impact on crop yields and production. We use a new approach of investigating high impact events: selecting by impact rather than by the extremeness of a chosen meteorological variable. This direct selection approach allows for compound extreme events (events caused by multiple, statistically related variables) to be included in the analysis and guarantees the events of highest societal importance are the focus of the study. We discuss the meteorological conditions that lead to the seasons of extreme crop production. We show that these are not necessarily extreme seasons in meteorological or climatic terms, since crop yield may vary due to relatively small deviations in, for example, temperature or precipitation at a significant periods in the growing season.

  6. Materials Degradation and Fatigue Under Extreme Conditions

    DTIC Science & Technology

    1997-10-29

    molecularly-thin fluids of very different structure were contrasted: a globular molecule, branched alkanes, and a polymer brush in near-theta solution...34 A. Dhinojwala, L. Cai, and S. Granick, Langmuir 12, 4537 (1996). 28. "New Approaches to Measure Interfacial Rheology of Confined Fluids ," A...Degradation of Fluorocarbon Lubricants; Molecular Tribology of Perfluoroether Lubricants; Fluids , Including Lubricants Under Extreme Conditions of

  7. Wave runup during extreme storm conditions

    NASA Astrophysics Data System (ADS)

    Senechal, Nadia; Coco, Giovanni; Bryan, Karin R.; Holman, Rob A.

    2011-07-01

    Video measurements of wave runup were collected during extreme storm conditions characterized by energetic long swells (peak period of 16.4 s and offshore height up to 6.4 m) impinging on steep foreshore beach slopes (0.05-0.08). These conditions induced highly dissipative and saturated conditions over the low-sloping surf zone while the swash zone was associated with moderately reflective conditions (Iribarren parameters up to 0.87). Our data support previous observations on highly dissipative beaches showing that runup elevation (estimated from the variance of the energy spectrum) can be scaled using offshore wave height alone. The data is consistent with the hypothesis of runup saturation at low frequencies (down to 0.035 Hz) and a hyperbolic-tangent fit provides the best statistical predictor of runup elevations.

  8. Bayesian quantitative precipitation forecasts in terms of quantiles

    NASA Astrophysics Data System (ADS)

    Bentzien, Sabrina; Friederichs, Petra

    2014-05-01

    Ensemble prediction systems (EPS) for numerical weather predictions on the mesoscale are particularly developed to obtain probabilistic guidance for high impact weather. An EPS not only issues a deterministic future state of the atmosphere but a sample of possible future states. Ensemble postprocessing then translates such a sample of forecasts into probabilistic measures. This study focus on probabilistic quantitative precipitation forecasts in terms of quantiles. Quantiles are particular suitable to describe precipitation at various locations, since no assumption is required on the distribution of precipitation. The focus is on the prediction during high-impact events and related to the Volkswagen Stiftung funded project WEX-MOP (Mesoscale Weather Extremes - Theory, Spatial Modeling and Prediction). Quantile forecasts are derived from the raw ensemble and via quantile regression. Neighborhood method and time-lagging are effective tools to inexpensively increase the ensemble spread, which results in more reliable forecasts especially for extreme precipitation events. Since an EPS provides a large amount of potentially informative predictors, a variable selection is required in order to obtain a stable statistical model. A Bayesian formulation of quantile regression allows for inference about the selection of predictive covariates by the use of appropriate prior distributions. Moreover, the implementation of an additional process layer for the regression parameters accounts for spatial variations of the parameters. Bayesian quantile regression and its spatially adaptive extension is illustrated for the German-focused mesoscale weather prediction ensemble COSMO-DE-EPS, which runs (pre)operationally since December 2010 at the German Meteorological Service (DWD). Objective out-of-sample verification uses the quantile score (QS), a weighted absolute error between quantile forecasts and observations. The QS is a proper scoring function and can be decomposed into

  9. Mixtures of planetary ices at extreme conditions.

    PubMed

    Lee, Mal-Soon; Scandolo, Sandro

    2011-02-08

    The interiors of Neptune and Uranus are believed to be primarily composed of a fluid mixture of methane and water. The mixture is subjected to pressures up to several hundred gigapascal, causing the ionization of water. Laboratory and simulation studies so far have focused on the properties of the individual components. Here we show, using first-principle molecular dynamic simulations, that the properties of the mixed fluid are qualitatively different with respect to those of its components at the same conditions. We observe a pressure-induced softening of the methane-water intermolecular repulsion that points to an enhancement of mixing under extreme conditions. Ionized water causes the progressive ionization of methane and the mixture becomes electronically conductive at milder conditions than pure water, indicating that the planetary magnetic field of Uranus and Neptune may originate at shallower depths than currently assumed.

  10. Injuries in an Extreme Conditioning Program.

    PubMed

    Aune, Kyle T; Powers, Joseph M

    2016-10-19

    Extreme conditioning programs (ECPs) are fitness training regimens relying on aerobic, plyometric, and resistance training exercises, often with high levels of intensity for a short duration of time. These programs have grown rapidly in popularity in recent years, but science describing the safety profile of these programs is lacking. The rate of injury in the extreme conditioning program is greater than the injury rate of weightlifting and the majority of injuries occur to the shoulder and back. Cross-sectional study. Level 4. This is a retrospective survey of injuries reported by athletes participating in an ECP. An injury survey was sent to 1100 members of Iron Tribe Fitness, a gym franchise with 5 locations across Birmingham, Alabama, that employs exercises consistent with an ECP in this study. An injury was defined as a physical condition resulting from ECP participation that caused the athlete to either seek medical treatment, take time off from exercising, or make modifications to his or her technique to continue. A total of 247 athletes (22%) completed the survey. The majority (57%) of athletes were male (n = 139), and 94% of athletes were white (n = 227). The mean age of athletes was 38.9 years (±8.9 years). Athletes reported participation in the ECP for, on average, 3.6 hours per week (± 1.2 hours). Eighty-five athletes (34%) reported that they had sustained an injury while participating in the ECP. A total of 132 injuries were recorded, yielding an estimated incidence of 2.71 per 1000 hours. The shoulder or upper arm was the most commonly injured body site, accounting for 38 injuries (15% of athletes). Athletes with a previous shoulder injury were 8.1 times as likely to injure their shoulder in the ECP compared with athletes with healthy shoulders. The trunk, back, head, or neck (n = 29, 12%) and the leg or knee (n = 29, 12%) were the second most commonly injured sites. The injury incidence rate among athletes with < 6 months of experience in the ECP

  11. Trends of some high quantiles of average and extremes inter-arrival times and rainfall depths at daily scale for an Italian Sub-Alpine area

    NASA Astrophysics Data System (ADS)

    Ferraris, Stefano; Agnese, Carmelo; Baiamonte, Giorgio; Canone, Davide; Previati, Maurizio; Cat Berro, Daniele; Mercalli, Luca

    2015-04-01

    Modeling of rainfall statistical structure represents an important research area in hydrology, meteorology, atmospheric physics and climatology, because of the several theoretical and practical implications. The statistical inference of the alternation of wet periods (WP) and dry periods (DP) in daily rainfall records can be achieved through the modelling of inter-arrival time-series (IT), defined as the succession of times elapsed from a rainy day and the one immediately preceding it. It has been shown previously that the statistical structure of IT can be well described by the 3-parameter Lerch distribution (Lch). In this work, Lch was successfully applied to IT data belonging to a sub-alpine area (Piemonte and Valle d'Aosta, NW Italy); furthermore the same statistical procedure was applied to daily rainfall records to ITs associated. The analysis has been carried out for 26 daily rainfall long-series (≈ 90 yr of observations). The main objective of this work was to detect temporal trends of some features describing the statistical structure of both inter-arrival time-series (IT) and associated rainfall depth (H). Each time-series was divided on subsets of five years long and for each of them the estimation of the Lch parameter was performed, so to extend the trend analysis to some high quantiles.

  12. Matter Under Extreme Conditions: The Early Years

    NASA Astrophysics Data System (ADS)

    Keeler, R. Norris; Gibson, Carl H.

    2012-03-01

    Extreme conditions in natural flows are examined, starting with a turbulent big bang. A hydro-gravitational-dynamics cosmology model is adopted. Planck-Kerr turbulence instability causes Planck-particle turbulent combustion. Inertial-vortex forces induce a non-turbulent ki- netic energy cascade to Planck-Kolmogorov scales where vorticity is produced, overcoming 10113 Pa Planck-Fortov pressures. The spinning, expanding fireball has a slight deficit of Planck antiparticles. Space and mass-energy powered by gluon viscous stresses expand exponentially at speeds >1025 c. Turbulent temperature and spin fluctuations fossilize at scales larger than ct, where c is light speed and t is time. Because "dark-energy" antigravity forces vanish when infla- tion ceases, and because turbulence produces entropy, the universe is closed and will collapse and rebound. Density and spin fossils of big bang turbulent mixing trigger structure formation in the plasma epoch. Fragmenting protosuperclustervoids and protoclustervoids produce weak tur- bulence until the plasma-gas transition give chains of protogalaxies with the morphology of tur- bulence. Chain galaxy clusters observed at large redshifts ~8.6 support this interpretation. Pro- togalaxies fragment into clumps, each with a trillion Earth-mass H-He gas planets. These make stars, supernovae, the first chemicals, the first oceans and the first life soon after the cosmologi- cal event.

  13. Extraordinary survival of nanobacteria under extreme conditions

    NASA Astrophysics Data System (ADS)

    Bjorklund, Michael; Ciftcioglu, Neva; Kajander, E. Olavi

    1998-07-01

    Nanobacteria show high resistance to gamma irradiation. To further examine their survival in extreme conditions several disinfecting and sterilizing chemicals as well as autoclaving, UV light, microwaves, heating and drying treatments were carried out. The effect of antibiotics used in cell culture were also evaluated. Two forms of nanobacteria were used in the tests: nanobacteria cultured in serum containing medium, and nanobacteria cultured in serum-free medium, the latter being more mineralized. Nanobacteria, having various amounts of apatite on their surfaces, were used to analyze the degree of protection given by the mineral. The chemicals tested included ethanol, glutaraldehyde, formalin, hypochlorite, hydrogen peroxide, hydrochloric acid, sodium hydroxide, detergents, and commercial disinfectants at concentrations generally used for disinfection. After chemical and physical treatments for various times, the nanobacteria were subcultered to detect their survival. The results show unique and wide resistance of nanobacteria to common agents used in disinfection. It can also be seen that the mineralization of the nanobacterial surface furthermore increases the resistance. Survival of nanobacteria is unique among living bacteria, but it can be compared with that observed in spores. Interestingly, nanobacteria have metabolic rate as slow as bacterial spores. A slow metabolic rate and protective structures, like mineral, biofilm and impermeable cell wall, can thus explain the observations made.

  14. Assessing surface air temperature variability using quantile regression

    NASA Astrophysics Data System (ADS)

    Timofeev, A. A.; Sterin, A. M.

    2014-12-01

    Many researches in climate change currently involve linear trends, based on measured variables. And many of them only consider trends in mean values, whereas it is clear, that not only means, but also whole shape of distribution changes over time and requires careful assessment. For example extreme values including outliers may get bigger, while median has zero slope.Quantile regression provides a convenient tool, that enables detailed analysis of changes in full range of distribution by producing a vector of quantile trends for any given set of quantiles.We have applied quantile regression to surface air temperature observations made at over 600 weather stations across Russian Federation during last four decades. The results demonstrate well pronounced regions with similar values of significant trends in different parts of temperature value distribution (left tail, middle part, right tail). The uncertainties of quantile trend estimations for several spatial patterns of trends over Russia are estimated and analyzed for each of four seasons.For temperature trend estimation over vast territories, quantile regression is an effort consuming approach, but is more informative than traditional instrument, to assess decadal evolution of temperature values, including evolution of extremes.Partial support of ERA NET RUS ACPCA joint project between EU and RBRF 12-05-91656-ЭРА-А is highly appreciated.

  15. Consistent model identification of varying coefficient quantile regression with BIC tuning parameter selection

    PubMed Central

    Zheng, Qi; Peng, Limin

    2016-01-01

    Quantile regression provides a flexible platform for evaluating covariate effects on different segments of the conditional distribution of response. As the effects of covariates may change with quantile level, contemporaneously examining a spectrum of quantiles is expected to have a better capacity to identify variables with either partial or full effects on the response distribution, as compared to focusing on a single quantile. Under this motivation, we study a general adaptively weighted LASSO penalization strategy in the quantile regression setting, where a continuum of quantile index is considered and coefficients are allowed to vary with quantile index. We establish the oracle properties of the resulting estimator of coefficient function. Furthermore, we formally investigate a BIC-type uniform tuning parameter selector and show that it can ensure consistent model selection. Our numerical studies confirm the theoretical findings and illustrate an application of the new variable selection procedure. PMID:28008212

  16. Analysis of retirement income adequacy using quantile regression: A case study in Malaysia

    NASA Astrophysics Data System (ADS)

    Alaudin, Ros Idayuwati; Ismail, Noriszura; Isa, Zaidi

    2015-09-01

    Quantile regression is a statistical analysis that does not restrict attention to the conditional mean and therefore, permitting the approximation of the whole conditional distribution of a response variable. Quantile regression is a robust regression to outliers compared to mean regression models. In this paper, we demonstrate how quantile regression approach can be used to analyze the ratio of projected wealth to needs (wealth-needs ratio) during retirement.

  17. Quantile regression provides a fuller analysis of speed data.

    PubMed

    Hewson, Paul

    2008-03-01

    Considerable interest already exists in terms of assessing percentiles of speed distributions, for example monitoring the 85th percentile speed is a common feature of the investigation of many road safety interventions. However, unlike the mean, where t-tests and ANOVA can be used to provide evidence of a statistically significant change, inference on these percentiles is much less common. This paper examines the potential role of quantile regression for modelling the 85th percentile, or any other quantile. Given that crash risk may increase disproportionately with increasing relative speed, it may be argued these quantiles are of more interest than the conditional mean. In common with the more usual linear regression, quantile regression admits a simple test as to whether the 85th percentile speed has changed following an intervention in an analogous way to using the t-test to determine if the mean speed has changed by considering the significance of parameters fitted to a design matrix. Having briefly outlined the technique and briefly examined an application with a widely published dataset concerning speed measurements taken around the introduction of signs in Cambridgeshire, this paper will demonstrate the potential for quantile regression modelling by examining recent data from Northamptonshire collected in conjunction with a "community speed watch" programme. Freely available software is used to fit these models and it is hoped that the potential benefits of using quantile regression methods when examining and analysing speed data are demonstrated.

  18. Dynamic ionization of water under extreme conditions

    SciTech Connect

    Goncharov, A F; Goldman, N; Fried, L E; Crowhurst, J C; Kuo, I W; Mundy, C J; Zaug, J M

    2004-07-19

    Raman spectroscopy has been used to study fluid water at approximately 1000 K and 2 to 60 GPa in a laser heated diamond anvil cell. First principles molecular dynamics (MD) simulations have also been employed to simulate water under similar conditions. The experimental Raman intensity of the O-H stretch mode was observed to decrease with pressure, and beyond 50 GPa this mode was no longer visible. At approximately the same pressure we inferred a change in the slope of the melting curve. Consistent with these experimental observations, the MD simulations show that water under these conditions forms a dynamically ionized liquid state, which is dominated by very short lived (<10 fs) H{sub 2}O, H{sub 3}O{sup +} and O{sup 2-} species.

  19. Simulations of Fluid Nitromethane Under Extreme Conditions

    SciTech Connect

    Fried, L E; Reed, E J; Manaa, M R

    2003-07-15

    We report density functional molecular dynamics simulations to determine the early chemical events of hot (T = 3000 K) and dense (1.97 g/cm{sup 3}, V/V{sub 0} = 0.68) nitromethane (CH{sub 3}NO{sub 2}). The first step in the decomposition process is an intermolecular proton abstraction mechanism that leads to the formation of CH{sub 3}NO{sub 2}H and the aci ion H{sub 2}CNO{sub 2}{sup -}, in support of evidence from static high-pressure and shock experiments. An intramolecular hydrogen transfer that transforms nitromethane into the aci acid form, CH{sub 2}NO{sub 2}H, accompanies this event. This is the first confirmation of chemical reactivity with bond selectivity for an energetic material near the condition of fully reacted specimen. We also report the decomposition mechanism followed up to the formation of H{sub 2}O as the first stable product.

  20. [Guidelines on asthma in extreme environmental conditions].

    PubMed

    Drobnic, Franchek; Borderías Clau, Luis

    2009-01-01

    Asthma is a highly prevalent chronic disease which, if not properly controlled, can limit the patient's activities and lifestyle. In recent decades, owing to the diffusion of educational materials, the application of clinical guidelines and, most importantly, the availability of effective pharmacological treatment, most patients with asthma are now able to lead normal lives. Significant social changes have also taken place during the same period, including more widespread pursuit of sporting activities and tourism. As a result of these changes, individuals with asthma can now participate in certain activities that were inconceivable for these patients only a few years ago, including winter sports, underwater activities, air flight, and travel to remote places with unusual environmental conditions (deserts, high mountain environments, and tropical regions). In spite of the publication of several studies on this subject, our understanding of the effects of these situations on patients with asthma is still limited. The Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) has decided to publish these recommendations based on the available evidence and expert opinion in order to provide information on this topic to both doctors and patients and to avert potentially dangerous situations that could endanger the lives of these patients.

  1. Pulmonary Edema in Healthy Subjects in Extreme Conditions

    PubMed Central

    Garbella, Erika; Catapano, Giosuè; Pratali, Lorenza; Pingitore, Alessandro

    2011-01-01

    There are several pieces of evidence showing occurrence of pulmonary edema (PE) in healthy subjects in extreme conditions consisting of extreme psychophysical demand in normal environment and psychophysical performances in extreme environment. A combination of different mechanisms, such as mechanical, hemodynamic, biochemical, and hypoxemic ones, may underlie PE leading to an increase in lung vascular hydrostatic pressure and lung vascular permeability and/or a downregulation of the alveolar fluid reabsorption pathways. PE can be functionally detected by closing volume measurement and lung diffusing capacity test to different gases or directly visualized by multiple imaging techniques. Among them chest ultrasonography can detect and quantify the extravascular lung water, creating “comet-tail” ultrasound artefacts (ULCs) from water-thickened pulmonary interlobular septa. In this paper the physiopathological mechanisms of PE, the functional and imaging techniques applied to detect and quantify the phenomenon, and three models of extreme conditions, that is, ironman athletes, climbers and breath-hold divers, are described. PMID:21766015

  2. Pulmonary edema in healthy subjects in extreme conditions.

    PubMed

    Garbella, Erika; Catapano, Giosuè; Pratali, Lorenza; Pingitore, Alessandro

    2011-01-01

    There are several pieces of evidence showing occurrence of pulmonary edema (PE) in healthy subjects in extreme conditions consisting of extreme psychophysical demand in normal environment and psychophysical performances in extreme environment. A combination of different mechanisms, such as mechanical, hemodynamic, biochemical, and hypoxemic ones, may underlie PE leading to an increase in lung vascular hydrostatic pressure and lung vascular permeability and/or a downregulation of the alveolar fluid reabsorption pathways. PE can be functionally detected by closing volume measurement and lung diffusing capacity test to different gases or directly visualized by multiple imaging techniques. Among them chest ultrasonography can detect and quantify the extravascular lung water, creating "comet-tail" ultrasound artefacts (ULCs) from water-thickened pulmonary interlobular septa. In this paper the physiopathological mechanisms of PE, the functional and imaging techniques applied to detect and quantify the phenomenon, and three models of extreme conditions, that is, ironman athletes, climbers and breath-hold divers, are described.

  3. Quantile Regression with Censored Data

    ERIC Educational Resources Information Center

    Lin, Guixian

    2009-01-01

    The Cox proportional hazards model and the accelerated failure time model are frequently used in survival data analysis. They are powerful, yet have limitation due to their model assumptions. Quantile regression offers a semiparametric approach to model data with possible heterogeneity. It is particularly powerful for censored responses, where the…

  4. Quantile Regression with Censored Data

    ERIC Educational Resources Information Center

    Lin, Guixian

    2009-01-01

    The Cox proportional hazards model and the accelerated failure time model are frequently used in survival data analysis. They are powerful, yet have limitation due to their model assumptions. Quantile regression offers a semiparametric approach to model data with possible heterogeneity. It is particularly powerful for censored responses, where the…

  5. Focus issue on the Study of Matter at Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Saini, Naurang L.; Saxena, Surendra K.; Bansil, Arun

    2015-09-01

    Study of matter at extreme conditions encompasses many different approaches for understanding the physics, chemistry and materials science underlying processes, products and technologies important for society. Although extreme conditions have been associated traditionally with research in areas of geology, mineral and earth sciences, the field has expanded in the recent years to include work on energy related materials and quantum functional materials from hard to soft matter. With the motivation to engage a large number of scientists with various disciplinary interests, ranging from physics, chemistry, geophysics to materials science, the study of matter at extreme conditions has been the theme of a series of conferences hosted by the High Pressure Science Society of America (HiPSSA) and the Center for the Study of Matter at Extreme Conditions (CeSMEC) of Florida International University (FIU), Miami. These SMEC (Study of Matter at Extreme Conditions) conferences are aimed at providing a unique platform for leading researchers to meet and share cutting-edge developments, and to bridge established fields under this interdisciplinary umbrella for research on materials. The seventh meeting in the SMEC series was held during March 23-30, 2013, while sailing from Miami to the Caribbean Islands, and concluded with great enthusiasm.

  6. Contrasting OLS and Quantile Regression Approaches to Student "Growth" Percentiles

    ERIC Educational Resources Information Center

    Castellano, Katherine Elizabeth; Ho, Andrew Dean

    2013-01-01

    Regression methods can locate student test scores in a conditional distribution, given past scores. This article contrasts and clarifies two approaches to describing these locations in terms of readily interpretable percentile ranks or "conditional status percentile ranks." The first is Betebenner's quantile regression approach that results in…

  7. Contrasting OLS and Quantile Regression Approaches to Student "Growth" Percentiles

    ERIC Educational Resources Information Center

    Castellano, Katherine Elizabeth; Ho, Andrew Dean

    2013-01-01

    Regression methods can locate student test scores in a conditional distribution, given past scores. This article contrasts and clarifies two approaches to describing these locations in terms of readily interpretable percentile ranks or "conditional status percentile ranks." The first is Betebenner's quantile regression approach that results in…

  8. Multiple imputation for cure rate quantile regression with censored data.

    PubMed

    Wu, Yuanshan; Yin, Guosheng

    2017-03-01

    The main challenge in the context of cure rate analysis is that one never knows whether censored subjects are cured or uncured, or whether they are susceptible or insusceptible to the event of interest. Considering the susceptible indicator as missing data, we propose a multiple imputation approach to cure rate quantile regression for censored data with a survival fraction. We develop an iterative algorithm to estimate the conditionally uncured probability for each subject. By utilizing this estimated probability and Bernoulli sample imputation, we can classify each subject as cured or uncured, and then employ the locally weighted method to estimate the quantile regression coefficients with only the uncured subjects. Repeating the imputation procedure multiple times and taking an average over the resultant estimators, we obtain consistent estimators for the quantile regression coefficients. Our approach relaxes the usual global linearity assumption, so that we can apply quantile regression to any particular quantile of interest. We establish asymptotic properties for the proposed estimators, including both consistency and asymptotic normality. We conduct simulation studies to assess the finite-sample performance of the proposed multiple imputation method and apply it to a lung cancer study as an illustration. © 2016, The International Biometric Society.

  9. Response of Simple, Model Systems to Extreme Conditions

    SciTech Connect

    Ewing, Rodney C.; Lang, Maik

    2015-07-30

    The focus of the research was on the application of high-pressure/high-temperature techniques, together with intense energetic ion beams, to the study of the behavior of simple oxide systems (e.g., SiO2, GeO2, CeO2, TiO2, HfO2, SnO2, ZnO and ZrO2) under extreme conditions. These simple stoichiometries provide unique model systems for the analysis of structural responses to pressure up to and above 1 Mbar, temperatures of up to several thousands of kelvin, and the extreme energy density generated by energetic heavy ions (tens of keV/atom). The investigations included systematic studies of radiation- and pressure-induced amorphization of high P-T polymorphs. By studying the response of simple stoichiometries that have multiple structural “outcomes”, we have established the basic knowledge required for the prediction of the response of more complex structures to extreme conditions. We especially focused on the amorphous state and characterized the different non-crystalline structure-types that result from the interplay of radiation and pressure. For such experiments, we made use of recent technological developments, such as the perforated diamond-anvil cell and in situ investigation using synchrotron x-ray sources. We have been particularly interested in using extreme pressures to alter the electronic structure of a solid prior to irradiation. We expected that the effects of modified band structure would be evident in the track structure and morphology, information which is much needed to describe theoretically the fundamental physics of track-formation. Finally, we investigated the behavior of different simple-oxide, composite nanomaterials (e.g., uncoated nanoparticles vs. core/shell systems) under coupled, extreme conditions. This provided insight into surface and boundary effects on phase stability under extreme conditions.

  10. Quantile Regression Models for Current Status Data.

    PubMed

    Ou, Fang-Shu; Zeng, Donglin; Cai, Jianwen

    2016-11-01

    Current status data arise frequently in demography, epidemiology, and econometrics where the exact failure time cannot be determined but is only known to have occurred before or after a known observation time. We propose a quantile regression model to analyze current status data, because it does not require distributional assumptions and the coefficients can be interpreted as direct regression effects on the distribution of failure time in the original time scale. Our model assumes that the conditional quantile of failure time is a linear function of covariates. We assume conditional independence between the failure time and observation time. An M-estimator is developed for parameter estimation which is computed using the concave-convex procedure and its confidence intervals are constructed using a subsampling method. Asymptotic properties for the estimator are derived and proven using modern empirical process theory. The small sample performance of the proposed method is demonstrated via simulation studies. Finally, we apply the proposed method to analyze data from the Mayo Clinic Study of Aging.

  11. Extreme conditions of elastic constants and principal axes of anisotropy

    NASA Astrophysics Data System (ADS)

    Ostrosablin, N. I.

    2016-07-01

    This paper describes the derivation of extreme conditions of each elasticity coefficient (Young's modulus, shear modulus, et al.,) for the general case of linear-elastic anisotropic materials. The stationarity conditions are obtained, and they determine the orthogonal coordinate systems being the principal axes of anisotropy, where the number of independent elasticity constants decreases from 21 to 18 and, in some cases of anisotropy, to 15 or lower. The example of a material with cubic symmetry is given.

  12. Quantile regression reveals hidden bias and uncertainty in habitat models

    Treesearch

    Brian S. Cade; Barry R. Noon; Curtis H. Flather

    2005-01-01

    We simulated the effects of missing information on statistical distributions of animal response that covaried with measured predictors of habitat to evaluate the utility and performance of quantile regression for providing more useful intervals of uncertainty in habitat relationships. These procedures were evaulated for conditions in which heterogeneity and hidden bias...

  13. Spline approximation of quantile functions

    NASA Technical Reports Server (NTRS)

    Schiess, J. R.; Matthews, C. G.

    1983-01-01

    The study reported here explored the development and utility of a spline representation of the sample quantile function of a continuous probability distribution in providing a functional description of a random sample and a method of generating random variables. With a spline representation, the random samples are generated by transforming a sample of uniform random variables to the interval of interest. This is useful, for example, in simulation studies in which a random sample represents the only known information about the distribution. The spline formulation considered here consists of a linear combination of cubic basis splines (B-splines) fit in a least squares sense to the sample quantile function using equally spaced knots. The following discussion is presented in five parts. The first section highlights major results realized from the study. The second section further details the results obtained. The methodology used is described in the third section, followed by a brief discussion of previous research on quantile functions. Finally, the results of the study are evaluated.

  14. Estimating equivalence with quantile regression

    USGS Publications Warehouse

    Cade, B.S.

    2011-01-01

    Equivalence testing and corresponding confidence interval estimates are used to provide more enlightened statistical statements about parameter estimates by relating them to intervals of effect sizes deemed to be of scientific or practical importance rather than just to an effect size of zero. Equivalence tests and confidence interval estimates are based on a null hypothesis that a parameter estimate is either outside (inequivalence hypothesis) or inside (equivalence hypothesis) an equivalence region, depending on the question of interest and assignment of risk. The former approach, often referred to as bioequivalence testing, is often used in regulatory settings because it reverses the burden of proof compared to a standard test of significance, following a precautionary principle for environmental protection. Unfortunately, many applications of equivalence testing focus on establishing average equivalence by estimating differences in means of distributions that do not have homogeneous variances. I discuss how to compare equivalence across quantiles of distributions using confidence intervals on quantile regression estimates that detect differences in heterogeneous distributions missed by focusing on means. I used one-tailed confidence intervals based on inequivalence hypotheses in a two-group treatment-control design for estimating bioequivalence of arsenic concentrations in soils at an old ammunition testing site and bioequivalence of vegetation biomass at a reclaimed mining site. Two-tailed confidence intervals based both on inequivalence and equivalence hypotheses were used to examine quantile equivalence for negligible trends over time for a continuous exponential model of amphibian abundance. ?? 2011 by the Ecological Society of America.

  15. Temporal and spatial variability of flood quantiles in the Upper Vistula River basin, Poland

    NASA Astrophysics Data System (ADS)

    Rutkowska, Agnieszka; Willems, Patrick; Onyutha, Charles; Młocek, Wojciech

    2017-04-01

    Temporal and spatial variability in extreme quantile anomalies of seasonal and annual maximum river flows was studied for 41 gauging stations at rivers in the Upper Vistula River basin (UVB), Poland. The Quantile Perturbation Method was used where relative differences between flood quantiles in a block and quantiles in the baseline were compared. Interdecadal oscillating components were extracted from the series of anomalies using the Hilbert-Huang transform method. Period length, part of variance of each component and part of unexplained variance were assessed. Results show an oscillating pattern in the temporal occurrence of extreme flow quantiles with clusters of high values in the 1960-70s and since the late 1990s, and of low values in the 1980s and at the beginning of the 1990s. The anomalies show a high variability on the right-bank of the UVB during the summer season with the highest values in catchments located in the western and south-western parts of the basin. Riverflow extreme quantiles were found to be associated with large-scale climatic variables from the regions of the North Atlantic Ocean, Scandinavia, Eastern Europe, Asia and, to a lesser extent, the Pacific Ocean. Similarities between temporal variability of river flows and climatic factors were revealed. Results of the study are important for flood frequency analysis because a long observation period is necessary to capture clusters of high and low river flows.

  16. Non-Stationary Hydrologic Frequency Analysis using B-Splines Quantile Regression

    NASA Astrophysics Data System (ADS)

    Nasri, B.; St-Hilaire, A.; Bouezmarni, T.; Ouarda, T.

    2015-12-01

    Hydrologic frequency analysis is commonly used by engineers and hydrologists to provide the basic information on planning, design and management of hydraulic structures and water resources system under the assumption of stationarity. However, with increasing evidence of changing climate, it is possible that the assumption of stationarity would no longer be valid and the results of conventional analysis would become questionable. In this study, we consider a framework for frequency analysis of extreme flows based on B-Splines quantile regression, which allows to model non-stationary data that have a dependence on covariates. Such covariates may have linear or nonlinear dependence. A Markov Chain Monte Carlo (MCMC) algorithm is used to estimate quantiles and their posterior distributions. A coefficient of determination for quantiles regression is proposed to evaluate the estimation of the proposed model for each quantile level. The method is applied on annual maximum and minimum streamflow records in Ontario, Canada. Climate indices are considered to describe the non-stationarity in these variables and to estimate the quantiles in this case. The results show large differences between the non-stationary quantiles and their stationary equivalents for annual maximum and minimum discharge with high annual non-exceedance probabilities. Keywords: Quantile regression, B-Splines functions, MCMC, Streamflow, Climate indices, non-stationarity.

  17. Forecasting peak asthma admissions in London: an application of quantile regression models.

    PubMed

    Soyiri, Ireneous N; Reidpath, Daniel D; Sarran, Christophe

    2013-07-01

    Asthma is a chronic condition of great public health concern globally. The associated morbidity, mortality and healthcare utilisation place an enormous burden on healthcare infrastructure and services. This study demonstrates a multistage quantile regression approach to predicting excess demand for health care services in the form of asthma daily admissions in London, using retrospective data from the Hospital Episode Statistics, weather and air quality. Trivariate quantile regression models (QRM) of asthma daily admissions were fitted to a 14-day range of lags of environmental factors, accounting for seasonality in a hold-in sample of the data. Representative lags were pooled to form multivariate predictive models, selected through a systematic backward stepwise reduction approach. Models were cross-validated using a hold-out sample of the data, and their respective root mean square error measures, sensitivity, specificity and predictive values compared. Two of the predictive models were able to detect extreme number of daily asthma admissions at sensitivity levels of 76 % and 62 %, as well as specificities of 66 % and 76 %. Their positive predictive values were slightly higher for the hold-out sample (29 % and 28 %) than for the hold-in model development sample (16 % and 18 %). QRMs can be used in multistage to select suitable variables to forecast extreme asthma events. The associations between asthma and environmental factors, including temperature, ozone and carbon monoxide can be exploited in predicting future events using QRMs.

  18. Conditional probability of rainfall extremes across multiple durations

    NASA Astrophysics Data System (ADS)

    Le, Phuong Dong; Leonard, Michael; Westra, Seth

    2017-04-01

    The conditional probability that extreme rainfall will occur at one location given that it is occurring at another location is critical in engineering design and management circumstances including planning of evacuation routes and the sitting of emergency infrastructure. A challenge with this conditional simulation is that in many situations the interest is not so much the conditional distributions of rainfall of the same duration at two locations, but rather the conditional distribution of flooding in two neighbouring catchments, which may be influenced by rainfall of different critical durations. To deal with this challenge, a model that can consider both spatial and duration dependence of extremes is required. The aim of this research is to develop a model that can take account both spatial dependence and duration dependence into the dependence structure of extreme rainfalls. To achieve this aim, this study is a first attempt at combining extreme rainfall for multiple durations within a spatial extreme model framework based on max-stable process theory. Max-stable processes provide a general framework for modelling multivariate extremes with spatial dependence for just a single duration extreme rainfall. To achieve dependence across multiple timescales, this study proposes a new approach that includes addition elements representing duration dependence of extremes to the covariance matrix of max-stable model. To improve the efficiency of calculation, a re-parameterization proposed by Koutsoyiannis et al. (1998) is used to reduce the number of parameters necessary to be estimated. This re-parameterization enables the GEV parameters to be represented as a function of timescale. A stepwise framework has been adopted to achieve the overall aims of this research. Firstly, the re-parameterization is used to define a new set of common parameters for marginal distribution across multiple durations. Secondly, spatial interpolation of the new parameter set is used to

  19. Estimating effects of limiting factors with regression quantiles

    USGS Publications Warehouse

    Cade, B.S.; Terrell, J.W.; Schroeder, R.L.

    1999-01-01

    In a recent Concepts paper in Ecology, Thomson et al. emphasized that assumptions of conventional correlation and regression analyses fundamentally conflict with the ecological concept of limiting factors, and they called for new statistical procedures to address this problem. The analytical issue is that unmeasured factors may be the active limiting constraint and may induce a pattern of unequal variation in the biological response variable through an interaction with the measured factors. Consequently, changes near the maxima, rather than at the center of response distributions, are better estimates of the effects expected when the observed factor is the active limiting constraint. Regression quantiles provide estimates for linear models fit to any part of a response distribution, including near the upper bounds, and require minimal assumptions about the form of the error distribution. Regression quantiles extend the concept of one-sample quantiles to the linear model by solving an optimization problem of minimizing an asymmetric function of absolute errors. Rank-score tests for regression quantiles provide tests of hypotheses and confidence intervals for parameters in linear models with heteroscedastic errors, conditions likely to occur in models of limiting ecological relations. We used selected regression quantiles (e.g., 5th, 10th, ..., 95th) and confidence intervals to test hypotheses that parameters equal zero for estimated changes in average annual acorn biomass due to forest canopy cover of oak (Quercus spp.) and oak species diversity. Regression quantiles also were used to estimate changes in glacier lily (Erythronium grandiflorum) seedling numbers as a function of lily flower numbers, rockiness, and pocket gopher (Thomomys talpoides fossor) activity, data that motivated the query by Thomson et al. for new statistical procedures. Both example applications showed that effects of limiting factors estimated by changes in some upper regression quantile (e

  20. Protein stability and molecular adaptation to extreme conditions.

    PubMed

    Jaenicke, R

    1991-12-18

    Proteins, due to the delicate balance of stabilizing and destabilizing interactions, are only marginally stable. Adaptation to extreme environments tends to shift the 'mesophilic' characteristics of proteins to the respective extremes of temperature, hydrostatic pressure, pH and salinity, such that, under the mutual physiological conditions, the molecular properties are similar regarding overall topology, flexibility and solvation. Enhanced intrinsic stability requires only minute local structural changes so that general strategies of stabilization cannot be established. Apart from mutative changes of amino-acid sequences, extrinsic factors (or cellular components) may be involved in 'extremophilic adaptation'. The molecular basis of acidophilic, alkalophilic and barophilic adaptation is still obscure. Mechanisms of enhanced thermal stability involve improved packing density, as well as specific local interactions. In halophiles, water and salt binding of the intrinsically stable protein inventory is accomplished by favoring acidic over basic amino acid residues and decreased hydrophobicity. General limits of viability are: (a) the susceptibility of the covalent structure of the polypeptide chain toward hydrolysis or hydrothermal degradation; (b) the competition of extreme solvent parameters with the weak electrostatic and hydrophobic interactions involved in protein stabilization; (c) perturbations of the folding and assembly of proteins; and (d) 'dislocation' of biochemical pathways due to effects of extreme conditions on the intricate network of metabolic reactions.

  1. Prebiotic cell membranes that survive extreme environmental pressure conditions.

    PubMed

    Kapoor, Shobhna; Berghaus, Melanie; Suladze, Saba; Prumbaum, Daniel; Grobelny, Sebastian; Degen, Patrick; Raunser, Stefan; Winter, Roland

    2014-08-04

    Attractive candidates for compartmentalizing prebiotic cells are membranes comprised of single-chain fatty acids. It is generally believed that life may have originated in the depth of the protoocean, that is, under high hydrostatic pressure conditions, but the structure and physical-chemical properties of prebiotic membranes under such conditions have not yet been explored. We report the temperature- and pressure-dependent properties of membranes composed of prebiotically highly-plausible lipids and demonstrate that prebiotic membranes could not only withstand extreme temperatures, but also serve as robust models of protocells operating in extreme pressure environments. We show that pressure not only increases the stability of vesicular systems but also limits their flexibility and permeability to solutes, while still keeping the membrane in an overall fluid-like and thus functional state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Ultrasonic Technique for Density Measurement of Liquids in Extreme Conditions

    PubMed Central

    Kazys, Rymantas; Sliteris, Reimondas; Rekuviene, Regina; Zukauskas, Egidijus; Mazeika, Liudas

    2015-01-01

    An ultrasonic technique, invariant to temperature changes, for a density measurement of different liquids under in situ extreme conditions is presented. The influence of geometry and material parameters of the measurement system (transducer, waveguide, matching layer) on measurement accuracy and reliability is analyzed theoretically along with experimental results. The proposed method is based on measurement of the amplitude of the ultrasonic wave, reflected from the interface of the solid/liquid medium under investigation. In order to enhance sensitivity, the use of a quarter wavelength acoustic matching layer is proposed. Therefore, the sensitivity of the measurement system increases significantly. Density measurements quite often must be performed in extreme conditions at high temperature (up to 220 °C) and high pressure. In this case, metal waveguides between piezoelectric transducer and the measured liquid are used in order to protect the conventional transducer from the influence of high temperature and to avoid depolarization. The presented ultrasonic density measurement technique is suitable for density measurement in different materials, including liquids and polymer melts in extreme conditions. A new calibration algorithm was proposed. The metrological evaluation of the measurement method was performed. The expanded measurement uncertainty Uρ = 7.4 × 10−3 g/cm3 (1%). PMID:26262619

  3. Multi-element stochastic spectral projection for high quantile estimation

    NASA Astrophysics Data System (ADS)

    Ko, Jordan; Garnier, Josselin

    2013-06-01

    We investigate quantile estimation by multi-element generalized Polynomial Chaos (gPC) metamodel where the exact numerical model is approximated by complementary metamodels in overlapping domains that mimic the model's exact response. The gPC metamodel is constructed by the non-intrusive stochastic spectral projection approach and function evaluation on the gPC metamodel can be considered as essentially free. Thus, large number of Monte Carlo samples from the metamodel can be used to estimate α-quantile, for moderate values of α. As the gPC metamodel is an expansion about the means of the inputs, its accuracy may worsen away from these mean values where the extreme events may occur. By increasing the approximation accuracy of the metamodel, we may eventually improve accuracy of quantile estimation but it is very expensive. A multi-element approach is therefore proposed by combining a global metamodel in the standard normal space with supplementary local metamodels constructed in bounded domains about the design points corresponding to the extreme events. To improve the accuracy and to minimize the sampling cost, sparse-tensor and anisotropic-tensor quadratures are tested in addition to the full-tensor Gauss quadrature in the construction of local metamodels; different bounds of the gPC expansion are also examined. The global and local metamodels are combined in the multi-element gPC (MEgPC) approach and it is shown that MEgPC can be more accurate than Monte Carlo or importance sampling methods for high quantile estimations for input dimensions roughly below N=8, a limit that is very much case- and α-dependent.

  4. The Matter in Extreme Conditions (MEC) instrument at LCLS

    NASA Astrophysics Data System (ADS)

    Nagler, Bob

    2015-06-01

    The last five years have seen the commissioning of and first user experiments on both the Free Electron Laser in Hamburg (FLASH) and the Linac Coherent Light Source (LCLS) in Stanford, and more are slated to come online in the next couple of years . The high photon frequency (i.e. larger than the plasma frequency of solid density), short pulse length (i.e. 10s to 100s of femtoseconds) and large photon number per pulse (i.e. 1012 photons per pulse) make it an ideal source to create and study states of matter at high energy density, a long-standing scientific challenge. Indeed, while matter in extreme conditions, which for the purpose of this talk we define as states under pressure up to hundreds of GPa and with temperatures ranging between 1eV and 1000eV, has been studied through dynamic shock compression and there has been significant progress made over many decades. However, large uncertainties still exist in the atomic structure and crystallographic structure, existence of high pressure phases, scattering factors, and equation of state of matter in extreme conditions. The Matter in Extreme Condition (MEC) instrument at LCLS is designed to overcome the unique experimental challenges that the study of matter in extreme conditions bring. It combines a suite of diagnostics and high power and energy optical lasers, which are standard fare in this research field, with the unmatched LCLS X-ray beam, to create an instrument that will be at the forefront of, and have a major impact on MEC science, in particular in the field of high pressure, warm dense matter, high energy density, and ultra-high intensity laser-matter interaction studies. The LCLS beam allows for unique investigation in all these extreme states using diagnostic methods such as X-ray Thomson Scattering, X-ray emission spectroscopy, X-ray diffraction, X-ray absorption spectroscopy, X-ray phase-contrast imaging, and pumping specific absorption lines to study (dense) plasma kinetics. Augmented with optical

  5. Wireless pilot monitoring system for extreme race conditions.

    PubMed

    Pino, Esteban J; Arias, Diego E; Aqueveque, Pablo; Melin, Pedro; Curtis, Dorothy W

    2012-01-01

    This paper presents the design and implementation of an assistive device to monitor car drivers under extreme conditions. In particular, this system is designed in preparation for the 2012 Atacama Solar Challenge to be held in the Chilean desert. Actual preliminary results show the feasibility of such a project including physiological and ambient sensors, real-time processing algorithms, wireless data transmission and a remote monitoring station. Implementation details and field results are shown along with a discussion of the main problems found in real-life telemetry monitoring.

  6. Solutions for Critical Raw Materials under Extreme Conditions: A Review

    PubMed Central

    Grilli, Maria Luisa; Bellezze, Tiziano; Gamsjäger, Ernst; Rinaldi, Antonio; Novak, Pavel; Balos, Sebastian; Piticescu, Radu Robert; Ruello, Maria Letizia

    2017-01-01

    In Europe, many technologies with high socio-economic benefits face materials requirements that are often affected by demand-supply disruption. This paper offers an overview of critical raw materials in high value alloys and metal-matrix composites used in critical applications, such as energy, transportation and machinery manufacturing associated with extreme working conditions in terms of temperature, loading, friction, wear and corrosion. The goal is to provide perspectives about the reduction and/or substitution of selected critical raw materials: Co, W, Cr, Nb and Mg. PMID:28772645

  7. Extreme fog events in Poland with respect to circulation conditions

    NASA Astrophysics Data System (ADS)

    Ustrnul, Z.; Czekierda, D.; Wypych, A.

    2010-09-01

    Fog is a phenomenon which belongs to a group of so-called hydrometeorites and, according to the different dictionaries, it is a suspension of water droplets or ice crystals in the ground layer of the air that impairs visibility in the horizontal direction below 1 km. The phenomenon of fog, although much less dynamic or violent than other extreme phenomena, such as thunderstorms or hail, is equally dangerous and brings about huge social and economic complications. Land and air transportation suffer and fog may sometimes leads to a complete crippling of the whole economy in an area where fog occurs. The main objective of the study is determination of the circulation types bringing extreme fog events in Poland. The duration of fog at each meteorological station was considered as the main input data originated from 54 synoptic stations located across the country. The mentioned data series cover the period of 56 years (1951-2006). The occurrence of fog depends on meteorological conditions caused to a large extent by a given synoptic situation and local terrain conditions. In this study, according to its objectives, only circulation conditions are taken into consideration. These have been described by 5 different circulation classifications (Grosswetterlagen, Litynski, Osuchowska-Klein, Niedzwiedz and Ustrnul). Situations when this phenomenon occurred across a large part of the country were taken into detailed consideration. Special attention was paid to fog coverage during 24-hour periods. In this work, in light of certain doubts about the homogeneity of the observation material available, the intensity of fog was not included, as it requires additional and very tedious analysis. In the first step all cases of fog during the 1966-2006 study period which lasted 24 hours at more than 10 of the considered weather stations, i.e: at least 5 stations have been considered. As expected, in most cases, either a centre of a classical high pressure system or a high pressure wedge

  8. Extreme Drought Conditions in the Rio Grande/Bravo Basin

    NASA Astrophysics Data System (ADS)

    Gutiérrez, F.; Dracup, J. A.

    2001-12-01

    The Treaty of February 3, 1944 entitled "Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande" between the U.S. and Mexico regulates the distribution of flows of the rivers between these two countries. The treaty is based on hydrological data available up to 1944. Using new (historical and paleoclimatological) data, the water balance presented in the Treaty is re-examinated and the 431,721,000 m3/year allocation for USA during "extreme drought conditions" is re-evaluated. The authors define "extreme drought conditions" for this basin and a hydrological drought analysis is carried out using a streamflow simulation model. The analysis is complemented with an analysis of the effects of the El Niño - Southern Oscillation and the Pacific Decadal Oscillation on precipitation and streamflow. The results of this research will be applicable to potential changes in the current water resources management policies on the basin. Given the social, economical and political importance of this basin, the findings of this research potentially will have significant impacts. This research is founded by the NSF fund SAHRA (Science and Technology Center to study and promote the "Sustainability of Water Resources in Semi-Arid Regions" at the University of Arizona).

  9. Quantile regression applied to spectral distance decay

    USGS Publications Warehouse

    Rocchini, D.; Cade, B.S.

    2008-01-01

    Remotely sensed imagery has long been recognized as a powerful support for characterizing and estimating biodiversity. Spectral distance among sites has proven to be a powerful approach for detecting species composition variability. Regression analysis of species similarity versus spectral distance allows us to quantitatively estimate the amount of turnover in species composition with respect to spectral and ecological variability. In classical regression analysis, the residual sum of squares is minimized for the mean of the dependent variable distribution. However, many ecological data sets are characterized by a high number of zeroes that add noise to the regression model. Quantile regressions can be used to evaluate trend in the upper quantiles rather than a mean trend across the whole distribution of the dependent variable. In this letter, we used ordinary least squares (OLS) and quantile regressions to estimate the decay of species similarity versus spectral distance. The achieved decay rates were statistically nonzero (p < 0.01), considering both OLS and quantile regressions. Nonetheless, the OLS regression estimate of the mean decay rate was only half the decay rate indicated by the upper quantiles. Moreover, the intercept value, representing the similarity reached when the spectral distance approaches zero, was very low compared with the intercepts of the upper quantiles, which detected high species similarity when habitats are more similar. In this letter, we demonstrated the power of using quantile regressions applied to spectral distance decay to reveal species diversity patterns otherwise lost or underestimated by OLS regression. ?? 2008 IEEE.

  10. Material dynamics under extreme conditions of pressure and strain rate

    SciTech Connect

    Remington, B A; Allen, P; Bringa, E; Hawreliak, J; Ho, D; Lorenz, K T; Lorenzana, H; Meyers, M A; Pollaine, S W; Rosolankova, K; Sadik, B; Schneider, M S; Swift, D; Wark, J; Yaakobi, B

    2005-09-06

    Solid state experiments at extreme pressures (10-100 GPa) and strain rates ({approx}10{sup 6}-10{sup 8}s{sup -1}) are being developed on high-energy laser facilities, and offer the possibility for exploring new regimes of materials science. These extreme solid-state conditions can be accessed with either shock loading or with a quasi-isentropic ramped pressure drive. Velocity interferometer measurements establish the high pressure conditions. Constitutive models for solid-state strength under these conditions are tested by comparing 2D continuum simulations with experiments measuring perturbation growth due to the Rayleigh-Taylor instability in solid-state samples. Lattice compression, phase, and temperature are deduced from extended x-ray absorption fine structure (EXAFS) measurements, from which the shock-induced {alpha}-{omega} phase transition in Ti and the {alpha}-{var_epsilon} phase transition in Fe are inferred to occur on sub-nanosec time scales. Time resolved lattice response and phase can also be measured with dynamic x-ray diffraction measurements, where the elastic-plastic (1D-3D) lattice relaxation in shocked Cu is shown to occur promptly (< 1 ns). Subsequent large-scale molecular dynamics (MD) simulations elucidate the microscopic dynamics that underlie the 3D lattice relaxation. Deformation mechanisms are identified by examining the residual microstructure in recovered samples. The slip-twinning threshold in single-crystal Cu shocked along the [001] direction is shown to occur at shock strengths of {approx}20 GPa, whereas the corresponding transition for Cu shocked along the [134] direction occurs at higher shock strengths. This slip-twinning threshold also depends on the stacking fault energy (SFE), being lower for low SFE materials. Designs have been developed for achieving much higher pressures, P > 1000 GPa, in the solid state on the National Ignition Facility (NIF) laser.

  11. Lower Extremity Overuse Conditions Affecting Figure Skaters During Daily Training

    PubMed Central

    Campanelli, Valentina; Piscitelli, Francesco; Verardi, Luciano; Maillard, Pauline; Sbarbati, Andrea

    2015-01-01

    Background Most ice figure skaters train and compete with ongoing issues in the lower extremities, which are often overlooked by the skaters and considered injuries only when they prevent the athletes from skating. Although not severe, these conditions impair the quality of daily training and compromise the skaters’ state of mind and performances. Purpose (1) To determine the point prevalence of the ongoing lower extremity overuse conditions in a population of ice figure skaters of all ages and levels and (2) to identify the risk factors contributing to the development of the most common ongoing conditions. Study Design Cross-sectional study; Level of evidence, 3. Methods A total of 95 skaters of all ages and skating levels were evaluated in a single examination in the middle of the competitive season. Data collection consisted of a questionnaire, clinical examination, and measurement of the skaters’ characteristics and the equipment used. Results Retrocalcaneal bursitis was the most common problem, affecting at least 1 foot in 34% of the skaters evaluated, followed by posterior heel skin calluses and superficial calcaneal bursitis, which affected 29% and 28% of skaters, respectively. The prevalence of the majority of these conditions was 10% to 32% higher in elite skaters than in nonelite skaters. Higher boot–foot length difference was associated with greater risk of superficial calcaneal bursitis in the landing foot of elite skaters, while higher body weight and greater in-skate ankle flexibility were associated with the development of retrocalcaneal bursitis in nonelite skaters. Only 30 skaters (32%) wore the appropriate boot size, while 57 skaters (51%) could not dorsiflex their ankles properly while wearing skates. Conclusion The heel represents a major area of concern for the high prevalence of calcaneal bursitis and calluses in proximity of the Achilles tendon, suggesting that improvements on the boot heel cup design should take priority. The

  12. The electrical conductivity of silicate liquids at extreme conditions

    NASA Astrophysics Data System (ADS)

    Scipioni, R.; Stixrude, L. P.

    2015-12-01

    Could the Earth have had a silicate dynamo early in its history? One requirement is that the electrical conductivity of silicate liquids be sufficiently high. However, very little is known about this property at the extreme conditions of pressure and temperature that prevailed in the magma ocean. We have computed from first principles molecular dynamics simulations the dc conductivity of liquid Silica SiO2 at pressure and temperature conditions spanning those of the magma ocean and super-Earth interiors. We find semi-metallic values of the conductivity at conditions typical of the putative basal magma ocean in the Early Earth. The variation of the conductivity with pressure and temperature displays interesting behavior that we rationalize on the basis of the closing the pseudo-gap at the Fermi level. For temperatures lower than T < 20,000 K electrical conductivity exhibits a maximum at intermediate compressions. We further explain this behavior in terms of stuctural changes that occur in silica liquid at high pressure; we find that the structure approaches that of the iso-electronic rare earth element Ne. We compare with Hugoniot data, including the equation of state, heat capacity, and reflectivity. The behavior of the heat capacity is different to that inferred from multiple Hugoniot experiments. These differences and the effect of including exact exchange on the calculations are discussed. Our results have important consequences for magnetic field generation in the early Earth and super-Earths.

  13. Observational Simulation of Icing in Extreme Weather Conditions

    NASA Astrophysics Data System (ADS)

    Gultepe, Ismail; Heymsfield, Andrew; Agelin-Chaab, Martin; Komar, John; Elfstrom, Garry; Baumgardner, Darrel

    2017-04-01

    Observations and prediction of icing in extreme weather conditions are important for aviation, transportation, and shipping applications, and icing adversely affects the economy. Icing environments can be studied either in the outdoor atmosphere or in the laboratory. There have been several aircraft based in-situ studies related to weather conditions affecting aviation operations, transportation, and marine shipping that includes icing, wind, and turbulence. However, studying severe weather conditions from aircraft observations are limited due to safety and sampling issues, instrumental uncertainties, and even the possibility of aircraft producing its own physical and dynamical effects. Remote sensing based techniques (e.g. retrieval techniques) for studying severe weather conditions represent usually a volume that cannot characterize the important scales and also represents indirect observations. Therefore, laboratory simulations of atmospheric processes can help us better understand the interactions among microphysical and dynamical processes. The Climatic Wind Tunnel (CWT) in ACE at the University of Ontario Institute of Technology (UOIT) has a large semi-open jet test chamber with flow area 7-13 m2 that can precisely control temperatures down to -40°C, and up to 250 km hr-1 wind speeds, for heavy or dry snow conditions with low visibility, similar to ones observed in the Arctic and cold climate regions, or at high altitude aeronautical conditions. In this study, the ACE CWT employed a spray nozzle array suspended in its settling chamber and fed by pressurized water, creating various particle sizes from a few microns up to mm size range. This array, together with cold temperature and high wind speed, enabled simulation of severe weather conditions, including icing, visibility, strong wind and turbulence, ice fog and frost, freezing fog, heavy snow and blizzard conditions. In this study, the test results will be summarized, and their application to aircraft

  14. Quantiles for Finite Mixtures of Normal Distributions

    ERIC Educational Resources Information Center

    Rahman, Mezbahur; Rahman, Rumanur; Pearson, Larry M.

    2006-01-01

    Quantiles for finite mixtures of normal distributions are computed. The difference between a linear combination of independent normal random variables and a linear combination of independent normal densities is emphasized. (Contains 3 tables and 1 figure.)

  15. Quantile treatment effects of job loss on health.

    PubMed

    Schiele, Valentin; Schmitz, Hendrik

    2016-09-01

    Studies on health effects of job loss mostly estimate mean effects. We argue that the effects might differ over the distribution of the health status and use quantile regression methods to provide a more complete picture. To take the potential endogeneity of job loss into account, we estimate quantile treatment effects where we rely on job loss due to plant closures. We find that the effect of job loss indeed varies across the mental and physical health distribution. Job loss due to plant closures affects physical health adversely for individuals in the middle and lower part of the health distribution while those in best physical condition do not seem to be affected. The results for mental health, though less distinct, point in the same direction. We find no effects on BMI.

  16. Analysis of the labor productivity of enterprises via quantile regression

    NASA Astrophysics Data System (ADS)

    Türkan, Semra

    2017-07-01

    In this study, we have analyzed the factors that affect the performance of Turkey's Top 500 Industrial Enterprises using quantile regression. The variable about labor productivity of enterprises is considered as dependent variable, the variableabout assets is considered as independent variable. The distribution of labor productivity of enterprises is right-skewed. If the dependent distribution is skewed, linear regression could not catch important aspects of the relationships between the dependent variable and its predictors due to modeling only the conditional mean. Hence, the quantile regression, which allows modelingany quantilesof the dependent distribution, including the median,appears to be useful. It examines whether relationships between dependent and independent variables are different for low, medium, and high percentiles. As a result of analyzing data, the effect of total assets is relatively constant over the entire distribution, except the upper tail. It hasa moderately stronger effect in the upper tail.

  17. Simulating Quantile Models with Applications to Economics and Management

    NASA Astrophysics Data System (ADS)

    Machado, José A. F.

    2010-05-01

    The massive increase in the speed of computers over the past forty years changed the way that social scientists, applied economists and statisticians approach their trades and also the very nature of the problems that they could feasibly tackle. The new methods that use intensively computer power go by the names of "computer-intensive" or "simulation". My lecture will start with bird's eye view of the uses of simulation in Economics and Statistics. Then I will turn out to my own research on uses of computer- intensive methods. From a methodological point of view the question I address is how to infer marginal distributions having estimated a conditional quantile process, (Counterfactual Decomposition of Changes in Wage Distributions using Quantile Regression," Journal of Applied Econometrics 20, 2005). Illustrations will be provided of the use of the method to perform counterfactual analysis in several different areas of knowledge.

  18. Charge transfer in TATB and HMX under extreme conditions.

    PubMed

    Zhang, Chaoyang; Ma, Yu; Jiang, Daojian

    2012-11-01

    Charge transfer is usually accompanied by structural changes in materials under different conditions. However, the charge transfer in energetic materials that are subjected to extreme conditions has seldom been explored by researchers. In the work described here, the charge transfer in single molecules and unit cells of the explosives TATB and HMX under high temperatures and high pressures was investigated by performing static and dynamic calculations using three DFT methods, including the PWC functional of LDA, and the BLYP and PBE functionals of GGA. The results showed that negative charge is transferred from the nitro groups of molecular or crystalline TATB and HMX when they are heated. All DFT calculations for the compressed TATB unit cell indicate that, generally, negative charge transfer occurs to its nitro groups as the compression increases. PWC and PBE calculations for crystalline HMX show that negative charge is first transferred to the nitro groups but, as the compression increases, the negative charge is transferred from the nitro groups. However, the BLYP calculations indicated that there was gradual negative charge transfer to the nitro groups of HMX, similar to the case for TATB. The unrelaxed state of the uniformly compressed TATB causes negative charge to be transferred from its nitro groups, in contrast to what is seen in the relaxed state. Charge transfer in TATB is predicted to occur much more easily than in HMX.

  19. Porous materials for thermal management under extreme conditions.

    PubMed

    Clyne, T W; Golosnoy, I O; Tan, J C; Markaki, A E

    2006-01-15

    A brief analysis is presented of how heat transfer takes place in porous materials of various types. The emphasis is on materials able to withstand extremes of temperature, gas pressure, irradiation, etc. i.e. metals and ceramics, rather than polymers. A primary aim is commonly to maximize either the thermal resistance (i.e. provide insulation) or the rate of thermal equilibration between the material and a fluid passing through it (i.e. to facilitate heat exchange). The main structural characteristics concern porosity (void content), anisotropy, pore connectivity and scale. The effect of scale is complex, since the permeability decreases as the structure is refined, but the interfacial area for fluid-solid heat exchange is, thereby, raised. The durability of the pore structure may also be an issue, with a possible disadvantage of finer scale structures being poor microstructural stability under service conditions. Finally, good mechanical properties may be required, since the development of thermal gradients, high fluid fluxes, etc. can generate substantial levels of stress. There are, thus, some complex interplays between service conditions, pore architecture/scale, fluid permeation characteristics, convective heat flow, thermal conduction and radiative heat transfer. Such interplays are illustrated with reference to three examples: (i) a thermal barrier coating in a gas turbine engine; (ii) a Space Shuttle tile; and (iii) a Stirling engine heat exchanger. Highly porous, permeable materials are often made by bonding fibres together into a network structure and much of the analysis presented here is oriented towards such materials.

  20. Extreme hydrothermal conditions at an active plate-bounding fault

    NASA Astrophysics Data System (ADS)

    Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G. R.; Janku-Capova, Lucie; Carpenter, Brett M.; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R.; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

    2017-06-01

    Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

  1. Extreme hydrothermal conditions at an active plate-bounding fault.

    PubMed

    Sutherland, Rupert; Townend, John; Toy, Virginia; Upton, Phaedra; Coussens, Jamie; Allen, Michael; Baratin, Laura-May; Barth, Nicolas; Becroft, Leeza; Boese, Carolin; Boles, Austin; Boulton, Carolyn; Broderick, Neil G R; Janku-Capova, Lucie; Carpenter, Brett M; Célérier, Bernard; Chamberlain, Calum; Cooper, Alan; Coutts, Ashley; Cox, Simon; Craw, Lisa; Doan, Mai-Linh; Eccles, Jennifer; Faulkner, Dan; Grieve, Jason; Grochowski, Julia; Gulley, Anton; Hartog, Arthur; Howarth, Jamie; Jacobs, Katrina; Jeppson, Tamara; Kato, Naoki; Keys, Steven; Kirilova, Martina; Kometani, Yusuke; Langridge, Rob; Lin, Weiren; Little, Timothy; Lukacs, Adrienn; Mallyon, Deirdre; Mariani, Elisabetta; Massiot, Cécile; Mathewson, Loren; Melosh, Ben; Menzies, Catriona; Moore, Jo; Morales, Luiz; Morgan, Chance; Mori, Hiroshi; Niemeijer, Andre; Nishikawa, Osamu; Prior, David; Sauer, Katrina; Savage, Martha; Schleicher, Anja; Schmitt, Douglas R; Shigematsu, Norio; Taylor-Offord, Sam; Teagle, Damon; Tobin, Harold; Valdez, Robert; Weaver, Konrad; Wiersberg, Thomas; Williams, Jack; Woodman, Nick; Zimmer, Martin

    2017-06-01

    Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults.

  2. Manipulative therapy for lower extremity conditions: expansion of literature review.

    PubMed

    Brantingham, James W; Globe, Gary; Pollard, Henry; Hicks, Marian; Korporaal, Charmaine; Hoskins, Wayne

    2009-01-01

    The purpose of this study was to conduct a systematic review on manipulative therapy for lower extremity conditions and expand on a previously published literature review. The Scientific Commission of the Council on Chiropractic Guidelines and Practice Parameters (CCGPP) was charged with developing literature syntheses, organized by anatomical region, to evaluate and report on the evidence base for chiropractic care. This article is the outcome of this charge. As part of the CCGPP process, preliminary drafts of these articles were posted on the CCGPP Web site www.ccgpp.org (2006-8) to allow for an open process and the broadest possible mechanism for stakeholder input. The Cumulative Index to Nursing and Allied Health Literature; PubMed; Manual, Alternative, and Natural Therapy Index System; Science Direct; and Index to Chiropractic Literature were searched from December 2006 to February 2008. Search terms included chiropractic, osteopathic, orthopedic, or physical therapy and MeSH terms for each region. Inclusion criteria required a diagnosis and manipulative therapy (mobilization and manipulation grades I-V) with or without adjunctive care. Exclusion criteria were pain referred from spinal sites (without diagnosis), referral for surgery, and conditions contraindicated for manipulative therapy. Clinical trials were assessed using a modified Scottish Intercollegiate Guidelines Network ranking system. Of the total 389 citations captured, 39 were determined to be relevant. There is a level of C or limited evidence for manipulative therapy combined with multimodal or exercise therapy for hip osteoarthritis. There is a level of B or fair evidence for manipulative therapy of the knee and/or full kinetic chain, and of the ankle and/or foot, combined with multimodal or exercise therapy for knee osteoarthritis, patellofemoral pain syndrome, and ankle inversion sprain. There is also a level of C or limited evidence for manipulative therapy of the ankle and/or foot combined

  3. Simultaneous multiple non-crossing quantile regression estimation using kernel constraints

    PubMed Central

    Liu, Yufeng; Wu, Yichao

    2011-01-01

    Quantile regression (QR) is a very useful statistical tool for learning the relationship between the response variable and covariates. For many applications, one often needs to estimate multiple conditional quantile functions of the response variable given covariates. Although one can estimate multiple quantiles separately, it is of great interest to estimate them simultaneously. One advantage of simultaneous estimation is that multiple quantiles can share strength among them to gain better estimation accuracy than individually estimated quantile functions. Another important advantage of joint estimation is the feasibility of incorporating simultaneous non-crossing constraints of QR functions. In this paper, we propose a new kernel-based multiple QR estimation technique, namely simultaneous non-crossing quantile regression (SNQR). We use kernel representations for QR functions and apply constraints on the kernel coefficients to avoid crossing. Both unregularised and regularised SNQR techniques are considered. Asymptotic properties such as asymptotic normality of linear SNQR and oracle properties of the sparse linear SNQR are developed. Our numerical results demonstrate the competitive performance of our SNQR over the original individual QR estimation. PMID:22190842

  4. Ab initio Raman spectroscopy of water under extreme conditions

    NASA Astrophysics Data System (ADS)

    Rozsa, Viktor; Pan, Ding; Wan, Quan; Galli, Giulia

    Water exhibits one of the most complex phase diagrams of any binary compound. Despite extensive studies, the melting lines of high-pressure ice phases remain very controversial, with reports differing by hundreds of Kelvin. The boundary between ice VII and liquid phase is particularly disputed, with recent work exploring plasticity and amorphization mediating the transition. Raman measurements are often used to fingerprint melting, yet their interpretation is difficult without atomistic modeling. Here, we report a study of high P/T water where we computed Raman spectra using a method combining ab initio molecular dynamics and density functional perturbation theory, as implemented in the Qbox code. Spectra were computed for the liquid at 10 and 20 GPa, both at 1000 K, and for solid ice VII (20 GPa, 500 K). Decomposing the spectra into inter and intra molecular contributions provided insight into the dynamics of the hydrogen-bonded network at extreme conditions. The relevance of our simulation results for models of water in Earth, Uranus, and Neptune will be discussed, and an interpretation of existing experiments at high pressure will be presented.

  5. Focusing adaptive-optics for neutron spectroscopy at extreme conditions

    SciTech Connect

    Simeoni, G. G.; Valicu, R. G.; Borchert, G.; Böni, P.; Rasmussen, N. G.; Yang, F.; Kordel, T.; Holland-Moritz, D.; Kargl, F.; Meyer, A.

    2015-12-14

    Neutron Spectroscopy employing extreme-conditions sample environments is nowadays a crucial tool for the understanding of fundamental scientific questions as well as for the investigation of materials and chemical-physical properties. For all these kinds of studies, an increased neutron flux over a small sample area is needed. The prototype of a focusing neutron guide component, developed and produced completely at the neutron source FRM II in Garching (Germany), has been installed at the time-of-flight (TOF) disc-chopper neutron spectrometer TOFTOF and came into routine-operation. The design is based on the compressed Archimedes' mirror concept for finite-size divergent sources. It represents a unique device combining the supermirror technology with Adaptive Optics, suitable for broad-bandwidth thermal-cold TOF neutron spectroscopy (here optimized for 1.4–10 Å). It is able to squeeze the beam cross section down to a square centimeter, with a more than doubled signal-to-background ratio, increased efficiency at high scattering angles, and improved symmetry of the elastic resolution function. We present a comparison between the simulated and measured beam cross sections, as well as the performance of the instrument within real experiments. This work intends to show the unprecedented opportunities achievable at already existing instruments, along with useful guidelines for the design and construction of next-generation neutron spectrometers.

  6. Focusing adaptive-optics for neutron spectroscopy at extreme conditions

    NASA Astrophysics Data System (ADS)

    Simeoni, G. G.; Valicu, R. G.; Borchert, G.; Böni, P.; Rasmussen, N. G.; Yang, F.; Kordel, T.; Holland-Moritz, D.; Kargl, F.; Meyer, A.

    2015-12-01

    Neutron Spectroscopy employing extreme-conditions sample environments is nowadays a crucial tool for the understanding of fundamental scientific questions as well as for the investigation of materials and chemical-physical properties. For all these kinds of studies, an increased neutron flux over a small sample area is needed. The prototype of a focusing neutron guide component, developed and produced completely at the neutron source FRM II in Garching (Germany), has been installed at the time-of-flight (TOF) disc-chopper neutron spectrometer TOFTOF and came into routine-operation. The design is based on the compressed Archimedes' mirror concept for finite-size divergent sources. It represents a unique device combining the supermirror technology with Adaptive Optics, suitable for broad-bandwidth thermal-cold TOF neutron spectroscopy (here optimized for 1.4-10 Å). It is able to squeeze the beam cross section down to a square centimeter, with a more than doubled signal-to-background ratio, increased efficiency at high scattering angles, and improved symmetry of the elastic resolution function. We present a comparison between the simulated and measured beam cross sections, as well as the performance of the instrument within real experiments. This work intends to show the unprecedented opportunities achievable at already existing instruments, along with useful guidelines for the design and construction of next-generation neutron spectrometers.

  7. Fast temperature spectrometer for samples under extreme conditions

    SciTech Connect

    Zhang, Dongzhou; Jackson, Jennifer M.; Sturhahn, Wolfgang; Zhao, Jiyong; Alp, E. Ercan; Toellner, Thomas S.; Hu, Michael Y.

    2015-01-15

    We have developed a multi-wavelength Fast Temperature Readout (FasTeR) spectrometer to capture a sample’s transient temperature fluctuations, and reduce uncertainties in melting temperature determination. Without sacrificing accuracy, FasTeR features a fast readout rate (about 100 Hz), high sensitivity, large dynamic range, and a well-constrained focus. Complimenting a charge-coupled device spectrometer, FasTeR consists of an array of photomultiplier tubes and optical dichroic filters. The temperatures determined by FasTeR outside of the vicinity of melting are, generally, in good agreement with results from the charge-coupled device spectrometer. Near melting, FasTeR is capable of capturing transient temperature fluctuations, at least on the order of 300 K/s. A software tool, SIMFaster, is described and has been developed to simulate FasTeR and assess design configurations. FasTeR is especially suitable for temperature determinations that utilize ultra-fast techniques under extreme conditions. Working in parallel with the laser-heated diamond-anvil cell, synchrotron Mössbauer spectroscopy, and X-ray diffraction, we have applied the FasTeR spectrometer to measure the melting temperature of {sup 57}Fe{sub 0.9}Ni{sub 0.1} at high pressure.

  8. Modeling energy expenditure in children and adolescents using quantile regression.

    PubMed

    Yang, Yunwen; Adolph, Anne L; Puyau, Maurice R; Vohra, Firoz A; Butte, Nancy F; Zakeri, Issa F

    2013-07-15

    Advanced mathematical models have the potential to capture the complex metabolic and physiological processes that result in energy expenditure (EE). Study objective is to apply quantile regression (QR) to predict EE and determine quantile-dependent variation in covariate effects in nonobese and obese children. First, QR models will be developed to predict minute-by-minute awake EE at different quantile levels based on heart rate (HR) and physical activity (PA) accelerometry counts, and child characteristics of age, sex, weight, and height. Second, the QR models will be used to evaluate the covariate effects of weight, PA, and HR across the conditional EE distribution. QR and ordinary least squares (OLS) regressions are estimated in 109 children, aged 5-18 yr. QR modeling of EE outperformed OLS regression for both nonobese and obese populations. Average prediction errors for QR compared with OLS were not only smaller at the median τ = 0.5 (18.6 vs. 21.4%), but also substantially smaller at the tails of the distribution (10.2 vs. 39.2% at τ = 0.1 and 8.7 vs. 19.8% at τ = 0.9). Covariate effects of weight, PA, and HR on EE for the nonobese and obese children differed across quantiles (P < 0.05). The associations (linear and quadratic) between PA and HR with EE were stronger for the obese than nonobese population (P < 0.05). In conclusion, QR provided more accurate predictions of EE compared with conventional OLS regression, especially at the tails of the distribution, and revealed substantially different covariate effects of weight, PA, and HR on EE in nonobese and obese children.

  9. [Sports and extreme conditions. Cardiovascular incidence in long term exertion and extreme temperatures (heat, cold)].

    PubMed

    Melin, B; Savourey, G

    2001-06-30

    During ultra-endurance exercise, both increase in body temperature and dehydration due to sweat losses, lead to a decrease in central blood volume. The heart rate drift allows maintaining appropriate cardiac output, in order to satisfy both muscle perfusion and heat transfer requirements by increasing skin blood flow. The resulting dehydration can impair thermal regulation and increase the risks of serious accidents as heat stroke. Endurance events, lasting more than 8 hours, result in large sweat sodium chloride losses. Thus, ingestion of large amounts of water with poor salt intake can induce symptomatic hyponatremia (plasma sodium < 130 mEq/L) which is also a serious accident. Heat environment increases the thermal constraint and when the air humidity is high, evaporation of sweat is compromise. Thus, thermal stress becomes uncompensable which increases the risk of cardiovascular collapse. Cold exposure induces physiological responses to maintain internal temperature by both limiting thermal losses and increasing metabolic heat production. Cold can induce accidental hypothermia and local frost-bites; moreover, it increases the risk of arrhythmia during exercise. Some guidelines (cardiovascular fitness, water and electrolyte intakes, protective clothing) are given for each extreme condition.

  10. Orographic Signature on Multiscale Statistics of Extreme Rainfall: Conditional downscaling with emphasis on extremes

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, E.; Ebtehaj, M.

    2010-09-01

    Rainfall intensity and spatio-temporal patterns often show a strong dependency on the underlying terrain. The main objective of this work is to study the statistical signature imprinted by orography on the spatial structure of rainfall and its temporal evolution at multiple scales, with the aim to develop a consistent theoretical basis for conditional downscaling of precipitation given the topographic information of the underlying terrain. The results of an extensive analysis of the high resolution stage II Doppler radar data of the Rapidan storm, June 1995, over the Appalachian Mountains is reported in this study. The orographic signature on the elementary statistical structure of the precipitation fields is studied via a variable-intensity thresholding scheme. This signature is further explored at multiple scales via analysis of the dependence of precipitation fields on the underlying terrain both in Fourier and Wavelet domains. The Generalized Normal distribution is found to be a suitable probability model to explain the variability of the rainfall wavelet coefficients and its dependence on the underlying elevations. These results provide a new perspective for more accurate statistical downscaling of the orographic precipitation over complex terrain with emphasis on extremes.

  11. Extreme Conditioning Programs: Potential Benefits and Potential Risks.

    PubMed

    Knapik, Joseph J

    2015-01-01

    CrossFit, Insanity, Gym Jones, and P90X are examples of extreme conditioning programs (ECPs). ECPs typically involve high-volume and high-intensity physical activities with short rest periods between movements and use of multiple joint exercises. Data on changes in fitness with ECPs are limited to CrossFit investigations that demonstrated improvements in muscle strength, muscular endurance, aerobic fitness, and body composition. However, no study has directly compared CrossFit or other ECPs to other more traditional forms of aerobic and resistance training within the same investigation. These direct comparisons are needed to more adequately evaluate the effectiveness of ECPs. Until these studies emerge, the comparisons with available literature suggest that improvements in CrossFit, in terms of muscular endurance (push-ups, sit-ups), strength, and aerobic capacity, appear to be similar to those seen in more traditional training programs. Investigations of injuries in ECPs are limited to two observational studies that suggest that the overall injury rate is similar to that seen in other exercise programs. Several cases of rhabdomyolysis and cervical carotid artery dissections have been reported during CrossFit training. The symptoms, diagnosis, and treatment of these are reviewed here. Until more data on ECPs emerge, physical training should be aligned with US Army doctrine. If ECPs are included in exercise programs, trainers should (1) have appropriate training certifications, (2) inspect exercise equipment regularly to assure safety, (3) introduce ECPs to new participants, (4) ensure medical clearance of Soldiers with special health problems before participation in ECPs, (4) tailor ECPs to the individual Soldier, (5) adjust rest periods to optimize recovery and reduce fatigue, (6) monitor Soldiers for signs of overtraining, rhabdomyolysis, and other problems, and (7) coordinate exercise programs with other unit training activities to eliminate redundant activities

  12. Thorium Chemistry in Oxo-Tellurium System under Extreme Conditions.

    PubMed

    Xiao, Bin; Kegler, Philip; Bosbach, Dirk; Alekseev, Evgeny V

    2017-03-06

    Through the use of a high-temperature/high-pressure synthesis method, four thorium oxo-tellurium compounds with different tellurium valence states were isolated. The novel inorganic phases illustrate the intrinsic complexity of the actinide tellurium chemistry under extreme conditions of pressure and temperature. Th2Te3O11 is the first instance of a mixed-valent oxo-tellurium compound, and at the same time, Te exhibits three different coordination environments (Te(IV)O3, Te(IV)O4, and Te(VI)O6) within a single structure. These three types of Te polyhedra are further fused together, resulting in a [Te3O11](8-) fragment. Na4Th2(Te(VI)3O15) and K2Th(Te(VI)O4)3 are the first alkaline thorium tellurates described in the literature. Both compounds are constructed from ThO9 tricapped trigonal prisms and Te(VI)O6 octahedra. Na4Th2(Te(VI)3O15) is a three-dimensional framework based on Th2O15 and Te2O10 dimers, while K2Th(Te(VI)O4)3 contains tungsten oxide bronze like Te layers linked by ThO9 polyhedra. The structure of β-Th(Te(IV)O3)(SO4) is built from infinite thorium chains cross-linked by Te(IV)O3(2-) and SO4(2-) anions. Close structural analysis suggests that β-Th(Te(IV)O3)(SO4) is highly related to the structure of α-Th(SeO4)2. Additionally, the Raman spectra are recorded and the characteristic peaks are assigned based on a comparison of reported tellurites or tellurates.

  13. Final Report for Project. Quark matter under extreme conditions

    SciTech Connect

    Incera, Vivian; Ferrer, Efrain

    2015-12-31

    The results obtained in the two years of the grant have served to shine new light on several important questions about the phases of quantum chromodynamics (QCD) under extreme conditions that include quark matter at high density, as well quark-gluon plasma at high temperatures, both in the presence of strong magnetic fields. The interest in including an external magnetic field on these studies is motivated by the generation of large magnetic fields in off-central heavy-ion collisions and by their common presence in astrophysical compact objects, the two scenarios where the physics of quark matter becomes relevant. The tasks carried out in this DOE project led us, among other things, to discover the first connection between the physics of very dense quark matter and novel materials as for instance topological insulators and Weyl semimetals; they allowed us to find a physical explanation for and a solution to a standing puzzle in the apparent effect of a magnetic field on the critical temperature of the QCD chiral transition; and they led us to establish by the first time that the core of the observed two-solar-mass neutron stars could be made up of quark matter in certain inhomogeneous chiral phases in a magnetic field and that this was consistent with current astrophysical observations. A major goal established by the Nuclear Science Advisory committee in its most recent report “Reaching for the Horizon” has been “to truly understand how nuclei and strongly interacting matter in all its forms behave and can predict their behavior in new settings.” The results found in this DOE project have all contributed to address this goal, and thus they are important for advancing fundamental knowledge in the area of nuclear physics and for enhancing our understanding of the role of strong magnetic fields in the two settings where they are most relevant, neutron stars and heavy-ion collisions.

  14. The Reactivity of Energetic Materials At Extreme Conditions

    SciTech Connect

    Fried, L E

    2006-10-23

    shock conditions, for example, energetic materials undergo rapid heating to a few thousand degrees and are subjected to a compression of hundreds of kilobars, resulting in almost 30% volume reduction. Complex chemical reactions are thus initiated, in turn releasing large amounts of energy to sustain the detonation process. Clearly, understanding of the various chemical events at these extreme conditions is essential in order to build predictive material models. Scientific investigations into the reactive process have been undertaken over the past two decades. However, the sub-{micro}s time scale of explosive reactions, in addition to the highly exothermic conditions of an explosion, make experimental investigation of the decomposition pathways difficult at best. More recently, new computational approaches to investigate condensed-phase reactivity in energetic materials have been developed. Here we focus on two different approaches to condensed-phase reaction modeling: chemical equilibrium methods and atomistic modeling of condensed-phase reactions. These are complementary approaches to understanding the chemical reactions of high explosives. Chemical equilibrium modeling uses a highly simplified thermodynamic picture of the reaction process, leading to a convenient and predictive model of detonation and other decomposition processes. Chemical equilibrium codes are often used in the design of new materials, both at the level of synthesis chemistry and formulation. Atomistic modeling is a rapidly emerging area. The doubling of computational power approximately every 18 months has made atomistic condensed-phase modeling more feasible. Atomistic calculations employ far fewer empirical parameters than chemical equilibrium calculations. Nevertheless, the atomistic modeling of chemical reactions requires an accurate global Born-Oppenheimer potential energy surface. Traditionally, such a surface is constructed by representing the potential energy surface with an analytical fit

  15. A quantile count model of water depth constraints on Cape Sable seaside sparrows

    USGS Publications Warehouse

    Cade, B.S.; Dong, Q.

    2008-01-01

    1. A quantile regression model for counts of breeding Cape Sable seaside sparrows Ammodramus maritimus mirabilis (L.) as a function of water depth and previous year abundance was developed based on extensive surveys, 1992-2005, in the Florida Everglades. The quantile count model extends linear quantile regression methods to discrete response variables, providing a flexible alternative to discrete parametric distributional models, e.g. Poisson, negative binomial and their zero-inflated counterparts. 2. Estimates from our multiplicative model demonstrated that negative effects of increasing water depth in breeding habitat on sparrow numbers were dependent on recent occupation history. Upper 10th percentiles of counts (one to three sparrows) decreased with increasing water depth from 0 to 30 cm when sites were not occupied in previous years. However, upper 40th percentiles of counts (one to six sparrows) decreased with increasing water depth for sites occupied in previous years. 3. Greatest decreases (-50% to -83%) in upper quantiles of sparrow counts occurred as water depths increased from 0 to 15 cm when previous year counts were 1, but a small proportion of sites (5-10%) held at least one sparrow even as water depths increased to 20 or 30 cm. 4. A zero-inflated Poisson regression model provided estimates of conditional means that also decreased with increasing water depth but rates of change were lower and decreased with increasing previous year counts compared to the quantile count model. Quantiles computed for the zero-inflated Poisson model enhanced interpretation of this model but had greater lack-of-fit for water depths > 0 cm and previous year counts 1, conditions where the negative effect of water depths were readily apparent and fitted better with the quantile count model.

  16. Matter in Extreme Conditions Instrument - Conceptual Design Report

    SciTech Connect

    Boyce, R.F.; Boyce, R.M.; Haller, G.; Hastings, J.B.; Hays, G.; Lee, H.J.; Lee, R.W.; Nagler, B.; Scharfenstein, M.; Marsh, D.; White, W.E.; /SLAC

    2009-12-09

    The SLAC National Accelerator Laboratory (SLAC), in collaboration with Argonne National Laboratory (ANL), Lawrence Livermore National Laboratory (LLNL), and the University of California at Los Angeles (UCLA), is constructing a Free-Electron Laser (FEL) research facility. The FEL has already met its performance goals in the wavelength range 1.5 nm - 0.15 nm. This facility, the Linac Coherent Light Source (LCLS), utilizes the SLAC 2-Mile Linear Accelerator (linac) and will produce sub-picosecond pulses of short wavelength X-rays with very high peak brightness and almost complete transverse coherence. The final one-third of the SLAC linac is used as the source of electrons for the LCLS. The high energy electrons are transported across the SLAC Research Yard, into a tunnel which houses a long undulator. In passing through the undulator, the electrons are bunched by the force of their own synchrotron radiation and produce an intense, monochromatic, spatially coherent beam of X-rays. By varying the electron energy, the FEL X-ray wavelength is tunable from 1.5 nm to 0.15 nm. The LCLS includes two experimental halls as well as X-ray optics and infrastructure necessary to create a facility that can be developed for research in a variety of disciplines such as atomic physics, materials science, plasma physics and biosciences. This Conceptual Design Report, the authors believe, confirms the feasibility of designing and constructing an X-ray instrument in order to exploit the unique scientific capability of LCLS by creating extreme conditions and study the behavior of plasma under those controlled conditions. This instrument will address the Office of Science, Fusion Energy Sciences, mission objective related to study of Plasma and Warm Dense Matter as described in the report titled LCLS, the First Experiments, prepared by the LCLS Scientific Advisory Committee (SAC) in September 2000. The technical objective of the LCLS Matter in Extreme Conditions (MEC) Instrument project is

  17. Measuring the structure factor of simple fluids under extreme conditions

    NASA Astrophysics Data System (ADS)

    Weck, Gunnar

    2013-06-01

    The structure and dynamics of fluids, although a long standing matter of investigations, is still far from being well established. In particular, with the existence of a first order liquid-liquid phase transition (LLT) discovered in liquid phosphorus at 0.9 GPa and 1300 K it is now recognized that the fluid state could present complex structural changes. At present, very few examples of LLTs have been clearly evidenced, which may mean that a larger range of densities must be probed. First order transitions between a molecular and a polymeric liquid have been recently predicted by first principles calculations in liquid nitrogen at 88 GPa and 2000 K and in liquid CO2 at 45 GPa and 1850 K. The only device capable of reaching these extreme conditions is the diamond anvil cell (DAC), in which, the sample is sandwiched between two diamond anvils of thickness 100 times larger. Consequently, the diffracted signal from the sample is very weak compared to the Compton signal of the anvils, and becomes hardly measurable for pressures above ~20 GPa. A similar problem has been faced by the high pressure community using large volume press so as to drastically reduce the x-ray background from the sample environment. In the angle-dispersive diffraction configuration, it was proposed to use a multichannel collimator (MCC). This solution has been implemented to fit the constraints of the Paris-Edimburg (PE) large volume press and it is now routinely used on beamline ID27 of the European Synchrotron Radiation Facility. In this contribution, we present our adaptation of the MCC device accessible at ID27 for the DAC experiment. Because of the small sample volume a careful alignment procedure between the MCC slits and the DAC had to be implemented. The data analysis procedure initially developed by Eggert et al. has also been completed in order to take into account the complex contribution of the MCC slits. A large reduction of the Compton diffusion from the diamond anvils is obtained

  18. Extreme Anthropogenic Loads and the Northern Ecosystem Condition.

    PubMed

    Kryuchkov, Vasiliy V

    1993-11-01

    In the extreme North, the polar region of Siberian Russia, the largest mining and processing enterprises for metallic and nonmetallic ores, coal, oil, and gas are situated. The extremely vulnerable boreal and polar ecosystems of the North are responding adversely to the impact of these activities, and are in danger of collapse because of them. The mechanisms of such impacts, their formation, continuous extension, and merger have been studied. The deforested and destroyed areas of former forest-tundra and taiga ecosystems resemble the Arctic zones of a much harsher environment more than the typical Arctic zones where they occur.

  19. Extreme anthropogenic loads and the northern ecosystem condition

    SciTech Connect

    Kryuckkov, V.V. )

    1993-11-01

    In the extreme North, the polar region of siberian Russia, the largest mining and processing enterprises for metallic and nonmetallic ores, coal, oil, and gas are situated. The extremely vulnerable boreal and polar ecosystems of the north are responding adversely to the impact of these activities, and are in danger of collapse because of them. The mechanisms of such impacts, their formation, continuous extension, and merger have been studied. The deforested and destroyed areas of former forest-tundra and taiga ecosystems resemble the Arctic zones of a much harsher environment more than the typical Arctic zones where they occur. 5 refs., 3 figs., 2 tabs.

  20. Biological effects of extreme environmental conditions. [considering limits of biosphere

    NASA Technical Reports Server (NTRS)

    Imshenetskiy, A. A.

    1975-01-01

    Actions of extreme physical and chemical space factors on microorganisms and plants are elaborated in order to establish limits for the biosphere. Considered are effects of low and high temperatures; ionizing and ultraviolet radiation; various gases; and effects of vibration, desiccation and acceleration.

  1. OB-stars as extreme condition test beds

    NASA Astrophysics Data System (ADS)

    Puls, Joachim; Sundqvist, Jon O.; Rivero González, Jorge G.

    2011-07-01

    Massive stars are inherently extreme objects, in terms of radiation, mass loss, rotation, and sometimes also magnetic fields. Concentrating on a (personally biased) subset of processes related to pulsations, rapid rotation and its interplay with mass-loss, and the bi-stability mechanism, we will discuss how active (and normal) OB stars can serve as appropriate laboratories to provide further clues.

  2. Biological effects of extreme environmental conditions. [considering limits of biosphere

    NASA Technical Reports Server (NTRS)

    Imshenetskiy, A. A.

    1975-01-01

    Actions of extreme physical and chemical space factors on microorganisms and plants are elaborated in order to establish limits for the biosphere. Considered are effects of low and high temperatures; ionizing and ultraviolet radiation; various gases; and effects of vibration, desiccation and acceleration.

  3. Quantile regression in environmental health: Early life lead exposure and end-of-grade exams.

    PubMed

    Magzamen, Sheryl; Amato, Michael S; Imm, Pamela; Havlena, Jeffrey A; Coons, Marjorie J; Anderson, Henry A; Kanarek, Marty S; Moore, Colleen F

    2015-02-01

    Conditional means regression, including ordinary least squares (OLS), provides an incomplete picture of exposure-response relationships particularly if the primary interest resides in the tail ends of the distribution of the outcome. Quantile regression (QR) offers an alternative methodological approach in which the influence of independent covariates on the outcome can be specified at any location along the distribution of the outcome. We implemented QR to examine heterogeneity in the influence of early childhood lead exposure on reading and math standardized fourth grade tests. In children from two urban school districts (n=1,076), lead exposure was associated with an 18.00 point decrease (95% CI: -48.72, -3.32) at the 10th quantile of reading scores, and a 7.50 point decrease (95% CI: -15.58, 2.07) at the 90th quantile. Wald tests indicated significant heterogeneity of the coefficients across the distribution of quantiles. Math scores did not show heterogeneity of coefficients, but there was a significant difference in the lead effect at the 10th (β=-17.00, 95% CI: -32.13, -3.27) versus 90th (β=-4.50, 95% CI: -10.55, 4.50) quantiles. Our results indicate that lead exposure has a greater effect for children in the lower tail of exam scores, a result that is masked by conditional means approaches.

  4. Principles of Quantile Regression and an Application

    ERIC Educational Resources Information Center

    Chen, Fang; Chalhoub-Deville, Micheline

    2014-01-01

    Newer statistical procedures are typically introduced to help address the limitations of those already in practice or to deal with emerging research needs. Quantile regression (QR) is introduced in this paper as a relatively new methodology, which is intended to overcome some of the limitations of least squares mean regression (LMR). QR is more…

  5. On accuracy of upper quantiles estimation

    NASA Astrophysics Data System (ADS)

    Markiewicz, I.; Strupczewski, W. G.; Kochanek, K.

    2010-11-01

    Flood frequency analysis (FFA) entails the estimation of the upper tail of a probability density function (PDF) of annual peak flows obtained from either the annual maximum series or partial duration series. In hydrological practice, the properties of various methods of upper quantiles estimation are identified with the case of known population distribution function. In reality, the assumed hypothetical model differs from the true one and one cannot assess the magnitude of error caused by model misspecification in respect to any estimated statistics. The opinion about the accuracy of the methods of upper quantiles estimation formed from the case of known population distribution function is upheld. The above-mentioned issue is the subject of the paper. The accuracy of large quantile assessments obtained from the four estimation methods is compared to two-parameter log-normal and log-Gumbel distributions and their three-parameter counterparts, i.e., three-parameter log-normal and GEV distributions. The cases of true and false hypothetical models are considered. The accuracy of flood quantile estimates depends on the sample size, the distribution type (both true and hypothetical), and strongly depends on the estimation method. In particular, the maximum likelihood method loses its advantageous properties in case of model misspecification.

  6. On accuracy of upper quantiles estimation

    NASA Astrophysics Data System (ADS)

    Markiewicz, I.; Strupczewski, W. G.; Kochanek, K.

    2010-07-01

    Flood frequency analysis (FFA) entails estimation of the upper tail of a probability density function (PDF) of annual peak flows obtained from either the annual maximum series or partial duration series. In hydrological practice the properties of various estimation methods of upper quantiles are identified with the case of known population distribution function. In reality the assumed hypothetical model differs from the true one and one can not assess the magnitude of error caused by model misspecification in respect to any estimated statistics. The opinion about the accuracy of the methods of upper quantiles estimation formed from the case of known population distribution function is upheld. The above-mentioned issue is the subject of the paper. The accuracy of large quantile assessments obtained from the four estimation methods are compared for two-parameter log-normal and log-Gumbel distributions and their three-parameter counterparts, i.e., three-parameter log-normal and GEV distributions. The cases of true and false hypothetical model are considered. The accuracy of flood quantile estimates depend on the sample size, on the distribution type, both true and hypothetical, and strongly depend on the estimation method. In particular, the maximum likelihood method looses its advantageous properties in case of model misspecification.

  7. Evolution of extraordinarily low and high temperature, precipitation and runoff periods over Germany since 1950 - A quantile regression approach

    NASA Astrophysics Data System (ADS)

    Wagner, J.; Donner, R. V.

    2012-04-01

    Properly describing temporal changes in the occurrence of extreme high or low temperatures, precipitation and runoff is of key importance for properly assessing the potential local impacts of ongoing climatic changes and estimating possible future trends. Unfortunately, the applicability of traditional extreme value statistics to non-stationary climate data is often restricted by the available amount of data. As a possible alternative, quantile regression techniques allow estimating temporal trends in arbitrary quantiles of the distribution of the corresponding hydro-meteorological observables. Besides the basic linear variant, there are nonparametric approaches available that allow characterizing quantile trends without an explicit prescription of a certain functional form. In this work, we study observational records of German temperature and precipitation as well as runoff time series obtained using the hydrological model SWIM for the second half of the 20th century. Particularly, we compare trends in very high and low quantiles of the associated probability distribution functions and compare them to the outcome of classical extreme value statistics. Our results allow a detailed characterization of the regional patterns of quantile trends and their temporary increase and decrease.

  8. Stable pelagic vertebrate community structure through extreme Paleogene greenhouse conditions

    NASA Astrophysics Data System (ADS)

    Sibert, E. C.; Friedman, M.; Hull, P. M.; Hunt, G.; Norris, R. D.

    2016-02-01

    The species composition (structure) and energy transfer (function) of an ecosystem is reflected by the presence and type of consumers that it supports. Here we use ichthyoliths, microfossil fish teeth and shark denticles, to assess the ecological variability of the pelagic fish community structure and composition from the Late Cretaceous to the middle Eocene from a drill core in the South Pacific gyre (DSDP Site 596). We find that the overall vertebrate community structure, as measured by the relative abundance of sharks to ray-finned fishes, has a punctuated change at the Cretaceous/Paleogene mass extinction. The vertebrate community structure remained stable throughout the Paleogene despite a five-fold increase in overall abundance of ichthyoliths during the extreme greenhouse of the Early Eocene. Further, we use a novel system to quantify the morphological variation in fish teeth. We find that the morphospace occupied by the tooth assemblage is conserved throughout the interval, with a slight expansion following the Cretaceous-Paleogene mass extinction, and the evolution of a distinct morphotype-group around the Paleocene-Eocene boundary. While there are elevated rates of morphotype origination and extinction following the Cretaceous-Paleogene mass extinction, the extreme greenhouse warming of the Early Eocene and associated increase in fish production produce near-zero origination and extinction rates. The relative stability in composition of the pelagic vertebrate community during intervals of extreme climate change and across large ranges of total fish accumulation, suggests that pelagic ecosystem structure is robust to climate events, and that the overall structure of the pelagic fish community may be decoupled from both climate and ecosystem function.

  9. Quantile regression analyses of associated factors for body mass index in Korean adolescents.

    PubMed

    Kim, T H; Lee, E K; Han, E

    2015-05-01

    This study examined the influence of home and school environments, and individual health-risk behaviours on body weight outcomes in Korean adolescents. This was a cross-sectional observational study. Quantile regression models to explore heterogeneity in the association of specific factors with body mass index (BMI) over the entire conditional BMI distribution was used. A nationally representative web-based survey for youths was used. Paternal education level of college or more education was associated with lower BMI for girls, whereas college or more education of mothers was associated with higher BMI for boys; for both, the magnitude of association became larger at the upper quantiles of the conditional BMI distribution. Girls with good family economic status were more likely to have higher BMIs than those with average family economic status, particularly at the upper quantile of the conditional BMI distribution. Attending a co-ed school was associated with lower BMI for both genders with a larger association at the upper quantiles. Substantial screen time for TV watching, video games, or internet surfing was associated with a higher BMI with a larger association at the upper quantiles for both girls and boys. Dental prevention was negatively associated with BMI, whereas suicide consideration was positively associated with BMIs of both genders with a larger association at a higher quantile. These findings suggest that interventions aimed at behavioural changes and positive parental roles are needed to effectively address high adolescent BMI. Copyright © 2015 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

  10. Extreme extensibility of copper foil under compound forming conditions.

    PubMed

    Yu, Qingbo; Liu, Xianghua; Tang, Delin

    2013-12-19

    A copper foil with an extreme extensibility up to 43,684% was obtained without any intermediate annealing by means of asynchronous rolling with high tension. It was found that under the combination of compression, shearing and tension, the copper foil represents a wonderful phenomenon. As the reduction increases, the specimen hardness increases up to a peak value 138 HV0.05 when the foil thickness rolled to around 100 μm, and then it decreases down to 78 HV0.05 when the foil thickness rolled to the final size 19 μm. It tells us that the strain-softening effect occurs when the foil thickness is rolled down to a threshold level. The experimental results bring us some fresh ideas different with the traditional understanding on the strain-hardening mechanism of metals, which provides an experimental basis to establish the forming mechanism of the thin foil.

  11. Regularized quantile regression under heterogeneous sparsity with application to quantitative genetic traits

    PubMed Central

    He, Qianchuan; Kong, Linglong; Wang, Yanhua; Wang, Sijian; Chan, Timothy A.; Holland, Eric

    2016-01-01

    Genetic studies often involve quantitative traits. Identifying genetic features that influence quantitative traits can help to uncover the etiology of diseases. Quantile regression method considers the conditional quantiles of the response variable, and is able to characterize the underlying regression structure in a more comprehensive manner. On the other hand, genetic studies often involve high-dimensional genomic features, and the underlying regression structure may be heterogeneous in terms of both effect sizes and sparsity. To account for the potential genetic heterogeneity, including the heterogeneous sparsity, a regularized quantile regression method is introduced. The theoretical property of the proposed method is investigated, and its performance is examined through a series of simulation studies. A real dataset is analyzed to demonstrate the application of the proposed method. PMID:28133403

  12. The Extreme Conditions Beamline P02.2 and the Extreme Conditions Science Infrastructure at PETRA III

    PubMed Central

    Liermann, H.-P.; Konôpková, Z.; Morgenroth, W.; Glazyrin, K.; Bednarčik, J.; McBride, E. E.; Petitgirard, S.; Delitz, J. T.; Wendt, M.; Bican, Y.; Ehnes, A.; Schwark, I.; Rothkirch, A.; Tischer, M.; Heuer, J.; Schulte-Schrepping, H.; Kracht, T.; Franz, H.

    2015-01-01

    A detailed description is presented of the Extreme Conditions Beamline P02.2 for micro X-ray diffraction studies of matter at simultaneous high pressure and high/low temperatures at PETRA III, in Hamburg, Germany. This includes performance of the X-ray optics and instrumental resolution as well as an overview of the different sample environments available for high-pressure studies in the diamond anvil cell. Particularly emphasized are the high-brilliance and high-energy X-ray diffraction capabilities of the beamline in conjunction with the use of fast area detectors to conduct time-resolved compression studies in the millisecond time regime. Finally, the current capability of the Extreme Conditions Science Infrastructure to support high-pressure research at the Extreme Conditions Beamline and other PETRA III beamlines is described. PMID:26134794

  13. Chemistry of H2O and HF Under Extreme Conditions

    SciTech Connect

    Fried, L; Goldman, N; Kuo, I W; Mundy, C

    2005-11-28

    The predicted high pressure superionic phases of water and HF are investigated via ab initio molecular dynamics. These phases could potentially be achieved through either static compression with heating or through shock compression. We study water at densities of 2.0-3.0 g/cc (34-115 GPa) along the 2000K isotherm.We find that extremely rapid (superionic) diffusion of protons occurs in a fluid phase at pressures between 34 and 58 GPa. A transition to a stable body-centered cubic (bcc) O lattice with superionic proton conductivity is observed between 70 and 75 GPa, a much higher pressure than suggested in prior work. We find that all molecular species at pressures greater than 75 GPa are too short lived to be classified as bound states. Up to 95 GPa, we find a solid superionic phase characterized by covalent O-H bonding. Above 95 GPa, a transient network phase is found characterized by symmetric O-H hydrogen bonding with nearly 50% covalent character. Ab initio molecular dynamics simulations of HF were conducted at densities of 1.8-4.0 g/cc along the 900 K isotherm. According to our simulations, a unique form of (symmetric) hydrogen bonding could play a significant role in superionic conduction. Our work shows that superionic phases could be more prevalent in hydrogen bonded systems than previously thought, such as HCl and HBr.

  14. Quantile equivalence to evaluate compliance with habitat management objectives

    USGS Publications Warehouse

    Cade, Brian S.; Johnson, Pamela R.

    2011-01-01

    Equivalence estimated with linear quantile regression was used to evaluate compliance with habitat management objectives at Arapaho National Wildlife Refuge based on monitoring data collected in upland (5,781 ha; n = 511 transects) and riparian and meadow (2,856 ha, n = 389 transects) habitats from 2005 to 2008. Quantiles were used because the management objectives specified proportions of the habitat area that needed to comply with vegetation criteria. The linear model was used to obtain estimates that were averaged across 4 y. The equivalence testing framework allowed us to interpret confidence intervals for estimated proportions with respect to intervals of vegetative criteria (equivalence regions) in either a liberal, benefit-of-doubt or conservative, fail-safe approach associated with minimizing alternative risks. Simple Boolean conditional arguments were used to combine the quantile equivalence results for individual vegetation components into a joint statement for the multivariable management objectives. For example, management objective 2A required at least 809 ha of upland habitat with a shrub composition ≥0.70 sagebrush (Artemisia spp.), 20–30% canopy cover of sagebrush ≥25 cm in height, ≥20% canopy cover of grasses, and ≥10% canopy cover of forbs on average over 4 y. Shrub composition and canopy cover of grass each were readily met on >3,000 ha under either conservative or liberal interpretations of sampling variability. However, there were only 809–1,214 ha (conservative to liberal) with ≥10% forb canopy cover and 405–1,098 ha with 20–30%canopy cover of sagebrush ≥25 cm in height. Only 91–180 ha of uplands simultaneously met criteria for all four components, primarily because canopy cover of sagebrush and forbs was inversely related when considered at the spatial scale (30 m) of a sample transect. We demonstrate how the quantile equivalence analyses also can help refine the numerical specification of habitat objectives and explore

  15. Atmosphere and water loss from early Mars under extreme solar wind and extreme ultraviolet conditions.

    PubMed

    Terada, Naoki; Kulikov, Yuri N; Lammer, Helmut; Lichtenegger, Herbert I M; Tanaka, Takashi; Shinagawa, Hiroyuki; Zhang, Tielong

    2009-01-01

    The upper limits of the ion pickup and cold ion outflow loss rates from the early martian atmosphere shortly after the Sun arrived at the Zero-Age-Main-Sequence (ZAMS) were investigated. We applied a comprehensive 3-D multi-species magnetohydrodynamic (MHD) model to an early martian CO(2)-rich atmosphere, which was assumed to have been exposed to a solar XUV [X-ray and extreme ultraviolet (EUV)] flux that was 100 times higher than today and a solar wind that was about 300 times denser. We also assumed the late onset of a planetary magnetic dynamo, so that Mars had no strong intrinsic magnetic field at that early period. We found that, due to such extreme solar wind-atmosphere interaction, a strong magnetic field of about approximately 4000 nT was induced in the entire dayside ionosphere, which could efficiently protect the upper atmosphere from sputtering loss. A planetary obstacle ( approximately ionopause) was formed at an altitude of about 1000 km above the surface due to the drag force and the mass loading by newly created ions in the highly extended upper atmosphere. We obtained an O(+) loss rate by the ion pickup process, which takes place above the ionopause, of about 1.5 x 10(28) ions/s during the first < or =150 million years, which is about 10(4) times greater than today and corresponds to a water loss equivalent to a global martian ocean with a depth of approximately 8 m. Consequently, even if the magnetic protection due to the expected early martian magnetic dynamo is neglected, ion pickup and sputtering were most likely not the dominant loss processes for the planet's initial atmosphere and water inventory. However, it appears that the cold ion outflow into the martian tail, due to the transfer of momentum from the solar wind to the ionospheric plasma, could have removed a global ocean with a depth of 10-70 m during the first < or =150 million years after the Sun arrived at the ZAMS.

  16. Communities that thrive in extreme conditions captured from a freshwater lake.

    PubMed

    Low-Décarie, Etienne; Fussmann, Gregor F; Dumbrell, Alex J; Bell, Graham

    2016-09-01

    Organisms that can grow in extreme conditions would be expected to be confined to extreme environments. However, we were able to capture highly productive communities of algae and bacteria capable of growing in acidic (pH 2), basic (pH 12) and saline (40 ppt) conditions from an ordinary freshwater lake. Microbial communities may thus include taxa that are highly productive in conditions that are far outside the range of conditions experienced in their host ecosystem. The organisms we captured were not obligate extremophiles, but were capable of growing in both extreme and benign conditions. The ability to grow in extreme conditions may thus be a common functional attribute in microbial communities. © 2016 The Author(s).

  17. Behavior of whey protein concentrates under extreme storage conditions

    USDA-ARS?s Scientific Manuscript database

    The overseas demand for whey protein concentrates (WPC) has increased steadily in recent years. Emergency aid foods often include WPC, but shelf-life studies of whey proteins under different shipment and storage conditions have not been conducted in the last 50 yr. Microbial quality, compound form...

  18. Nonparametric inference on quantile lost lifespan.

    PubMed

    Balmert, Lauren; Jeong, Jong-Hyeon

    2017-03-01

    In this article, the existing concept of reversed percentile residual life, or percentile inactivity time, is recast to show that it can be used for routine analysis of time-to-event data under right censoring to summarize "life lost," which poses several advantages over the existing methods for survival analysis. An estimating equation approach is adopted to avoid estimation of the probability density function of the underlying time-to-event distribution to estimate the variance of the quantile estimator. Additionally a K-sample test statistic is proposed to test the ratio of the quantile lost lifespans. Simulation studies are performed to assess finite properties of the proposed K-sample statistic in terms of coverage probability and power. The proposed method is illustrated with a real data example from a breast cancer study.

  19. Resilience under conditions of extreme stress: a multilevel perspective.

    PubMed

    Cicchetti, Dante

    2010-10-01

    Resilience has been conceptualized as a dynamic developmental process encompassing the attainment of positive adaptation within the context of significant threat, severe adversity, or trauma. Until the past decade, the empirical study of resilience predominantly focused on behavioral and psychosocial correlates of, and contributors to, the phenomenon and did not examine neurobiological or genetic correlates of and contributors to resilience. Technological advances in molecular genetics and neuroimaging, and in measuring other biological aspects of behavior, have made it more feasible to begin to conduct research on pathways to resilient functioning from a multilevel perspective. Child maltreatment constitutes a profound immersion in severe stress that challenges and frequently impairs development across diverse domains of biological and psychological functioning. Research on the determinants of resilience in maltreated children is presented as an illustration of empirical work that is moving from single-level to multilevel investigations of competent functioning in the face of adversity and trauma. These include studies of personality, neural, neuroendocrine, and molecular genetic contributors to resilient adaptation. Analogous to neural plasticity that takes place in response to brain injury, it is conjectured that it may be possible to conceptualize resilience as the ability of individuals to recover functioning after exposure to extreme stress. Multilevel randomized control prevention and intervention trials have substantial potential for facilitating the promotion of resilient functioning in diverse high-risk populations that have experienced significant adversity. Determining the multiple levels at which change is engendered through randomized control trials will provide insight into the mechanisms of change, the extent to which neural plasticity may be promoted, and the interrelations between biological and psychological processes in the development of

  20. Resilience under conditions of extreme stress: a multilevel perspective

    PubMed Central

    CICCHETTI, DANTE

    2010-01-01

    Resilience has been conceptualized as a dynamic developmental process encompassing the attainment of positive adaptation within the context of significant threat, severe adversity, or trauma. Until the past decade, the empirical study of resilience predominantly focused on behavioral and psychosocial correlates of, and contributors to, the phenomenon and did not examine neurobiological or genetic correlates of and contributors to resilience. Technological advances in molecular genetics and neuroimaging, and in measuring other biological aspects of behavior, have made it more feasible to begin to conduct research on pathways to resilient functioning from a multilevel perspective. Child maltreatment constitutes a profound immersion in severe stress that challenges and frequently impairs development across diverse domains of biological and psychological functioning. Research on the determinants of resilience in maltreated children is presented as an illustration of empirical work that is moving from single-level to multilevel investigations of competent functioning in the face of adversity and trauma. These include studies of personality, neural, neuroendocrine, and molecular genetic contributors to resilient adaptation. Analogous to neural plasticity that takes place in response to brain injury, it is conjectured that it may be possible to conceptualize resilience as the ability of individuals to recover functioning after exposure to extreme stress. Multilevel randomized control prevention and intervention trials have substantial potential for facilitating the promotion of resilient functioning in diverse high-risk populations that have experienced significant adversity. Determining the multiple levels at which change is engendered through randomized control trials will provide insight into the mechanisms of change, the extent to which neural plasticity may be promoted, and the interrelations between biological and psychological processes in the development of

  1. The effect of field condition and shoe type on lower extremity injuries in American Football.

    PubMed

    Iacovelli, Jaclyn Nicole; Yang, Jingzhen; Thomas, Geb; Wu, Hongqian; Schiltz, Trisha; Foster, Danny T

    2013-08-01

    Considerable improvement has been made in football field surfaces and types of shoe, yet relatively few epidemiological studies have investigated their roles in the risk of football injuries. This study examined the effects of field surface, surface condition and shoe type on the likelihood of lower extremity football injuries. Deidentified data from 188 players from one division I university football team during the 2007-2010 seasons were analysed. Lower extremity injury rate and rate ratio, along with 95% confidence limits, were calculated by football activity, playing surface condition and shoe type. A total of 130 lower extremity injuries were sustained, with an overall lower extremity injury rate of 33.5/10 000 athlete-sessions. The lower extremity injury rate was 2.61 times higher when the surface condition was abnormal compared with when the surface condition was normal. During games, the risk for lower extremity injury was 3.34 times higher (95% CI 1.70 to 6.56) on artificial turf compared with natural grass. However, this trend was not statistically significant in practice sessions. Furthermore, neither the number of shoe cleats nor the height of the shoe top was statistically associated with risk of lower extremity injuries. Football players who played on artificial turf or when the surface condition was abnormal were susceptible to lower extremity injuries. Evidence from this study suggests that further research into playing surfaces and shoe types may provide fruitful opportunities to reduce injuries to collegiate football players.

  2. Extreme drought: summary of hydrologic conditions in Georgia, 2011

    USGS Publications Warehouse

    Knaak, Andrew E.; Frantz, Eric R.; Peck, Michael F.

    2013-01-01

    The United States Geological Survey (USGS) Georgia Water Science Center (GaWSC) maintains a long-term hydrologic monitoring network of more than 320 realtime streamgages, including 10 real-time lake-level monitoring stations and 63 realtime water-quality monitors. Additionally, the GaWSC operates more than 180 groundwater wells, 35 of which are real-time. One of the many benefits from this monitoring network is that the data analyses provide an overview of the hydrologic conditions of rivers, creeks, reservoirs, and aquifers in Georgia.

  3. Extreme drought-summary of hydrologic conditions in Georgia, 2012

    USGS Publications Warehouse

    Knaak, Andrew E.; Peck, Michael F.

    2014-01-01

    The U.S. Geological Survey (USGS) Georgia Water Science Center (GaWSC) maintains a long-term hydrologic monitoring network of more than 330 real-time streamgages, including 10 real-time lake-level monitoring stations, 63 real-time water-quality monitors, and 48 water-quality sampling stations. Additionally, the GaWSC operates more than 180 groundwater monitoring wells, 42 of which are real-time. One of the many benefits from this monitoring network is that the data analyses provide a well distributed overview of the hydrologic conditions of creeks, rivers, reservoirs, and aquifers in Georgia.

  4. Water-CO2 Mixtures Under Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Plattner, D. L.; Somayazulu, M.

    2010-12-01

    In situ high pressure-temperature Raman spectroscopy was used to investigate the formation of clathrates in water-CO2 mixtures and to study the chemical interactions between water and CO2 at supercritical conditions. Diamond anvil cell’s (DAC) were loaded with ruby, water, CO2, and a gold plated gasket. Quartz was later added to the cell as a pressure sensor for supercritical phase analysis. At 25 °C and within the pressure range of 0.8 to 2.6 GPa, no clathrate was observed. Our results confirm recent findings which also dispute claims of clathrate existence at our conditions. A decrease in the temperature required to reach the supercritical phase of water-CO2 mixtures was observed from 0.35 GPa to 4.5 GPa. Furthermore, at 4.4 GPa and 290 °C, a chemical reaction between CO2 and water occurred. The resulting compound has a Raman peak with a frequency shift of 1000 cm-1. This reaction and the compound it produces are of great interest and are currently being investigated.

  5. ANALYSIS ON CENSORED QUANTILE RESIDUAL LIFE MODEL VIA SPLINE SMOOTHING.

    PubMed

    Ma, Yanyuan; Wei, Ying

    2012-01-01

    We propose a general class of quantile residual life models, where a specific quantile of the residual life time, conditional on an individual has survived up to time t, is a function of certain covariates with their coefficients varying over time. The varying coefficients are assumed to be smooth unspecified functions of t. We propose to estimate the coefficient functions using spline approximation. Incorporating the spline representation directly into a set of unbiased estimating equations, we obtain a one-step estimation procedure, and we show that this leads to a uniformly consistent estimator. To obtain further computational simplification, we propose a two-step estimation approach in which we estimate the coefficients on a series of time points first, and follow this with spline smoothing. We compare the two methods in terms of their asymptotic efficiency and computational complexity. We further develop inference tools to test the significance of the covariate effect on residual life. The finite sample performance of the estimation and testing procedures are further illustrated through numerical experiments. We also apply the methods to a data set from a neurological study.

  6. Semiparametric Approach to a Random Effects Quantile Regression Model

    PubMed Central

    Kim, Mi-Ok; Yang, Yunwen

    2011-01-01

    We consider a random effects quantile regression analysis of clustered data and propose a semiparametric approach using empirical likelihood. The random regression coefficients are assumed independent with a common mean, following parametrically specified distributions. The common mean corresponds to the population-average effects of explanatory variables on the conditional quantile of interest, while the random coefficients represent cluster specific deviations in the covariate effects. We formulate the estimation of the random coefficients as an estimating equations problem and use empirical likelihood to incorporate the parametric likelihood of the random coefficients. A likelihood-like statistical criterion function is yield, which we show is asymptotically concave in a neighborhood of the true parameter value and motivates its maximizer as a natural estimator. We use Markov Chain Monte Carlo (MCMC) samplers in the Bayesian framework, and propose the resulting quasi-posterior mean as an estimator. We show that the proposed estimator of the population-level parameter is asymptotically normal and the estimators of the random coefficients are shrunk toward the population-level parameter in the first order asymptotic sense. These asymptotic results do not require Gaussian random effects, and the empirical likelihood based likelihood-like criterion function is free of parameters related to the error densities. This makes the proposed approach both flexible and computationally simple. We illustrate the methodology with two real data examples. PMID:22347760

  7. Quantile Regression for Analyzing Heterogeneity in Ultra-high Dimension

    PubMed Central

    Wang, Lan; Wu, Yichao

    2012-01-01

    Ultra-high dimensional data often display heterogeneity due to either heteroscedastic variance or other forms of non-location-scale covariate effects. To accommodate heterogeneity, we advocate a more general interpretation of sparsity which assumes that only a small number of covariates influence the conditional distribution of the response variable given all candidate covariates; however, the sets of relevant covariates may differ when we consider different segments of the conditional distribution. In this framework, we investigate the methodology and theory of nonconvex penalized quantile regression in ultra-high dimension. The proposed approach has two distinctive features: (1) it enables us to explore the entire conditional distribution of the response variable given the ultra-high dimensional covariates and provides a more realistic picture of the sparsity pattern; (2) it requires substantially weaker conditions compared with alternative methods in the literature; thus, it greatly alleviates the difficulty of model checking in the ultra-high dimension. In theoretic development, it is challenging to deal with both the nonsmooth loss function and the nonconvex penalty function in ultra-high dimensional parameter space. We introduce a novel sufficient optimality condition which relies on a convex differencing representation of the penalized loss function and the subdifferential calculus. Exploring this optimality condition enables us to establish the oracle property for sparse quantile regression in the ultra-high dimension under relaxed conditions. The proposed method greatly enhances existing tools for ultra-high dimensional data analysis. Monte Carlo simulations demonstrate the usefulness of the proposed procedure. The real data example we analyzed demonstrates that the new approach reveals substantially more information compared with alternative methods. PMID:23082036

  8. Matter under Extreme Conditions: Advances Based on Static Compression

    NASA Astrophysics Data System (ADS)

    Hemley, Russell

    2008-04-01

    Current technological advances make it possible to perform experiments on materials at static or sustained conditions to multimegabar pressures (several hundred GPa) and several thousand degree (˜1 eV) temperatures. Densities of condensed matter can now be increased over an order of magnitude, causing novel transformations and new physical and chemical phenomena to occur. Growth in this area has been made possible by advances in diamond-anvil cell methods coupled with a wide range of probes, including x-ray diffraction, spectroscopy, inelastic scattering, radiography, and infrared spectroscopy using synchrotron radiation. Examples include investigations of dense hydrogen; transformations in molecular materials; novel ceramics; new types of superconductors, electronic, and magnetic materials; and liquids and amorphous materials. Particularly exciting are new developments in time resolved methods and coupling of static and dynamic compression techniques made possible by the creation of new large-scale facilities and novel technologies.

  9. TRISO-Coated Fuel Durability Under Extreme Conditions

    SciTech Connect

    Reimanis, Ivar; Gorman, Brian; Butt, Darryl

    2014-03-30

    The PIs propose to examine TRISO-coated particles (SiC and ZrC coatings) in an integrated two-part study. In the first part, experiments will be performed to assess the reaction kinetics of the carbides under CO-CO2 environments at temperatures up to 1800 degree C. Kinetic model will be applied to describe the degradation. Scanning and transmission electron microscopy will be employed to establish the chemical and microstructure evolution under the imposed environmental conditions. The second part of the proposed work focuses on establishing the role of the high temperature, environmental exposure described above on the mechanical behavior of TRISO-coated particles. Electron microscopy and other advanced techniques will be subsequently performed to evaluate failure mechanisms. The work is expected to reveal relationships between corrosion reactions, starting material characteristics (polytype of SiC, impurity concentration, flaw distribution), flaw healing behavior, and crack growth.

  10. The Sphagnum microbiome supports bog ecosystem functioning under extreme conditions.

    PubMed

    Bragina, Anastasia; Oberauner-Wappis, Lisa; Zachow, Christin; Halwachs, Bettina; Thallinger, Gerhard G; Müller, Henry; Berg, Gabriele

    2014-09-01

    Sphagnum-dominated bogs represent a unique yet widely distributed type of terrestrial ecosystem and strongly contribute to global biosphere functioning. Sphagnum is colonized by highly diverse microbial communities, but less is known about their function. We identified a high functional diversity within the Sphagnum microbiome applying an Illumina-based metagenomic approach followed by de novo assembly and MG-RAST annotation. An interenvironmental comparison revealed that the Sphagnum microbiome harbours specific genetic features that distinguish it significantly from microbiomes of higher plants and peat soils. The differential traits especially support ecosystem functioning by a symbiotic lifestyle under poikilohydric and ombrotrophic conditions. To realise a plasticity-stability balance, we found abundant subsystems responsible to cope with oxidative and drought stresses, to exchange (mobile) genetic elements, and genes that encode for resistance to detrimental environmental factors, repair and self-controlling mechanisms. Multiple microbe-microbe and plant-microbe interactions were also found to play a crucial role as indicated by diverse genes necessary for biofilm formation, interaction via quorum sensing and nutrient exchange. A high proportion of genes involved in nitrogen cycle and recycling of organic material supported the role of bacteria for nutrient supply. 16S rDNA analysis indicated a higher structural diversity than that which had been previously detected using PCR-dependent techniques. Altogether, the diverse Sphagnum microbiome has the ability to support the life of the host plant and the entire ecosystem under changing environmental conditions. Beyond this, the moss microbiome presents a promising bio-resource for environmental biotechnology - with respect to novel enzymes or stress-protecting bacteria.

  11. Quantile regression modeling for Malaysian automobile insurance premium data

    NASA Astrophysics Data System (ADS)

    Fuzi, Mohd Fadzli Mohd; Ismail, Noriszura; Jemain, Abd Aziz

    2015-09-01

    Quantile regression is a robust regression to outliers compared to mean regression models. Traditional mean regression models like Generalized Linear Model (GLM) are not able to capture the entire distribution of premium data. In this paper we demonstrate how a quantile regression approach can be used to model net premium data to study the effects of change in the estimates of regression parameters (rating classes) on the magnitude of response variable (pure premium). We then compare the results of quantile regression model with Gamma regression model. The results from quantile regression show that some rating classes increase as quantile increases and some decrease with decreasing quantile. Further, we found that the confidence interval of median regression (τ = O.5) is always smaller than Gamma regression in all risk factors.

  12. Managing more than the mean: using quantile regression to identify factors related to large elk groups.

    PubMed

    Brennan, Angela; Cross, Paul C; Creel, Scott

    2015-12-01

    Animal group size distributions are often right-skewed, whereby most groups are small, but most individuals occur in larger groups that may also disproportionately affect ecology and policy. In this case, examining covariates associated with upper quantiles of the group size distribution could facilitate better understanding and management of large animal groups.We studied wintering elk groups in Wyoming, where group sizes span several orders of magnitude, and issues of disease, predation and property damage are affected by larger group sizes. We used quantile regression to evaluate relationships between the group size distribution and variables of land use, habitat, elk density and wolf abundance to identify conditions important to larger elk groups.We recorded 1263 groups ranging from 1 to 1952 elk and found that across all quantiles of group size, group sizes were larger in open habitat and on private land, but the largest effect occurred between irrigated and non-irrigated land [e.g. the 90th quantile group size increased by 135 elk (95% CI = 42, 227) on irrigation].Only upper quantile group sizes were positively related to broad-scale measures of elk density and wolf abundance. For wolf abundance, this effect was greater on elk groups found in open habitats and private land than those in closed habitats or public land. If we had limited our analysis to mean or median group sizes, we would not have detected these effects. Synthesis and applications. Our analysis of elk group size distributions using quantile regression suggests that private land, irrigation, open habitat, elk density and wolf abundance can affect large elk group sizes. Thus, to manage larger groups by removal or dispersal of individuals, we recommend incentivizing hunting on private land (particularly if irrigated) during the regular and late hunting seasons, promoting tolerance of wolves on private land (if elk aggregate in these areas to avoid wolves) and creating more winter range and

  13. Incipient and Progressive Damage in Polyethylene Under Extreme Tensile Conditions

    SciTech Connect

    Furmanski, Jevan; Brown, Eric; Trujillo, Carl P.; Martinez, Daniel Tito; Gray, George T. III

    2012-06-07

    The Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) test was developed at LANL by Gray and coworkers to probe the tensile response of materials at large strains (>1) and high strain-rates (>1000/s) by firing projectiles through a conical die at 300-700 m/s. This technique has recently been applied to various polymers, such as the fluoropolymers PTFE (Teflon) and the chemically similar PCTFE, which respectively exhibited catastrophic fragmentation and distributed dynamic necking. This work details investigations of the Dyn-Ten-Ext response of high density polyethylene, both to failure and sub-critical conditions. At large extrusion ratios ({approx}7.4) and high velocities, such as those previously employed, HDPE catastrophically fragmented in a craze-like manner in the extruded jet. At more modest extrusion ratios and high velocities the specimen extruded a stable jet that ruptured cleanly, and at lower velocities was recovered intact after sustaining substantial internal damage. Thermomechanical finite element simulations showed that the damage corresponded to a locus of shear stress in the presence of hydrostatic tension. X-ray computed tomography corroborated the prediction of a shear damage mechanism by finding the region of partially damaged material to consist of macroscopic shear-mode cracks nearly aligned with the extrusion axis, originating from the location of damage inception.

  14. Materials Science under Extreme Conditions of Pressure and Strain Rate

    SciTech Connect

    Remington, B A; Bazan, G; Bringa, E; Caturla, M; Edwards, M J; Glendinning, S G; Kad, B; Kalantar, D H; Kumar, M; Lasinski, B F; Lorenz, K T; McNaney, J; Meyerhofer, D; Meyers, M A; Pollaine, S M; Reisman, D B; Rowley, D; Schneider, M; Stolken, J; Wark, J; Yaakobi, B

    2003-03-27

    Solid state dynamics experiments at very high pressures (P >> 10 GPa) and strain rates ({var_epsilon} >> 10{sup 5} s{sup -1}) have been demonstrated on high energy laser facilities, albeit over brief intervals of time and small spatial scales. We have developed two methods for driving samples to high pressures (10-100 GPa) at high strain rate (10{sup 6}-10{sup 8} s{sup -1}) in the solid state. One method uses a shockless compression technique, and the other uses multiple staged shocks. These drives are calibrated with VISAR measurements of the resulting compression wave. Deformation mechanisms are inferred under these conditions by characterizing recovered samples. Material strength at high pressures and strain rates is deduced by measuring the reduced growth of material perturbations at a hydrodynamically unstable interface. Microscopic lattice response is determined by time-resolved Bragg diffraction and x-ray absorption spectroscopy (EXAFS). Large-scale simulations, both at the continuum level using constitutive models and at the lattice level using molecular dynamics simulation, are used to interpret these integral experiments. We will review our progress in this new area of laser-based materials science research, then present a vision for carrying these solid-state experiments to much higher pressures, P > 1000 GPa, on the National Ignition Facility (NIF) laser facility.

  15. Studies on carbon nanotubes and fullerenes under extreme conditions.

    PubMed

    Avasthi, D K; Kumar, Amit; Singhal, Rahul; Tripathi, Ambuj; Misra, D S

    2010-06-01

    Ion beam irradiation of materials can cause defect creation as well as defect annealing depending on the ion beam parameters such as ion fluence and the energy loss of ions in materials. In present review, we report the behaviour of carbon nanotubes under exteme conditions such as laser irradiation and ion irradiation. The reorientation of the crystalline planes in confined single crystal nickel nanorods inside carbon nano tube, induced by heavy ion irradiation, is reported. Axial buckling of nickel nanorods as well as walls of carbon nano tubes in nickel encapsulated carbon nano tubes under swift heavy ion irradiation at high fluence is observed. At high fluence, amorphization of nickel nanorods inside carbon nanotubes is also observed. Axial buckling and amorphization under ion irradiation at high fluence are dependent on the number of walls in carbon nanotubes. High resolution transmission electron microscopy was used to investigate the reorientations, buckling and amorphization of metal filled nanotubes. Synthesis of carbon nanowires by ion irradiation of fullerene and their field emission properties with comparison to that of unirradiated and irradiated carbon nanotubes are reported. An international scenario with future prospects of ion beam studies in carbon nanotube is briefed.

  16. A multiscale strength model for extreme loading conditions

    NASA Astrophysics Data System (ADS)

    Barton, N. R.; Bernier, J. V.; Becker, R.; Arsenlis, A.; Cavallo, R.; Marian, J.; Rhee, M.; Park, H.-S.; Remington, B. A.; Olson, R. T.

    2011-04-01

    We present a multiscale strength model in which strength depends on pressure, strain rate, temperature, and evolving dislocation density. Model construction employs an information passing paradigm to span from the atomistic level to the continuum level. Simulation methods in the overall hierarchy include density functional theory, molecular statics, molecular dynamics, dislocation dynamics, and continuum based approaches. Given the nature of the subcontinuum simulations upon which the strength model is based, the model is particularly appropriate to strain rates in excess of 104 s-1. Strength model parameters are obtained entirely from the hierarchy of simulation methods to obtain a full strength model in a range of loading conditions that so far has been inaccessible to direct measurement of material strength. Model predictions compare favorably with relevant high energy density physics (HEDP) experiments that have bearing on material strength. The model is used to provide insight into HEDP experimental observations and to make predictions of what might be observable using dynamic x-ray diffraction based experimental methods.

  17. Ultrastructural morphologic changes in mycobacterial biofilm in different extreme condition.

    PubMed

    Kumar, Virendra; Sachan, Tarun Kumar; Sharma, Pragya; Rawat, Krishna Dutta

    2015-02-01

    The aim of this study was to investigate the morphologic and ultrastructural features of biofilms of slow and fast-growing mycobacteria in different stress conditions, presence and absence of oleic acid albumin dextrose catalase (OADC) enrichment and at different temperatures: 30, 37 and 42 °C. Four hundred mycobacterial isolates were taken. The biomass of each biofilm was quantified using a modified microtiter plate assay method. Isolates were divided into those that formed fully established biofilms, moderately attached biofilms and weakly adherent biofilms by comparison with a known biofilm-forming strain. The large quantity of biofilm was produced by Mycobacterium smegmatis at temperature 37 and 42 °C as compared to 30 °C. Mycobacterium fortuitum and M. avium developed large amount of biofilm at 30 °C as compared to 37 and 42 °C. Mycobacterium tuberculosis developed strong biofilm at 37 °C and no biofilm at 30 and 42 °C in Sauton's media. The selected non-tuberculous mycobacteria and H37Rv developed strong biofilm in the presence of OADC enrichment in Sauton's medium. Microscopic examination of biofilms by scanning electron microscopy revealed that poorly adherent biofilm formers failed to colonize the entire surface of the microtiter well. While moderately adherent biofilm formers grew in uniform monolayers but failed to develop a mature three-dimensional structure. SEM analysis of an isolate representative of the group formed fully established biofilms with a textured, multi-layered, three-dimensional structure.

  18. The matter in extreme conditions instrument at the Linac Coherent Light Source

    SciTech Connect

    Nagler, Bob; Arnold, Brice; Bouchard, Gary; Boyce, Richard F.; Boyce, Richard M.; Callen, Alice; Campell, Marc; Curiel, Ruben; Galtier, Eric; Garofoli, Justin; Granados, Eduardo; Hastings, Jerry; Hays, Greg; Heimann, Philip; Lee, Richard W.; Milathianaki, Despina; Plummer, Lori; Schropp, Andreas; Wallace, Alex; Welch, Marc; White, William; Xing, Zhou; Yin, Jing; Young, James; Zastrau, Ulf; Lee, Hae Ja

    2015-04-21

    The LCLS beam provides revolutionary capabilities for studying the transient behavior of matter in extreme conditions. The particular strength of the Matter in Extreme Conditions instrument is that it combines the unique LCLS beam with high-power optical laser beams, and a suite of dedicated diagnostics tailored for this field of science. In this paper an overview of the beamline, the capabilities of the instrumentation, and selected highlights of experiments and commissioning results are presented.

  19. The Matter in Extreme Conditions instrument at the Linac Coherent Light Source

    PubMed Central

    Nagler, Bob; Arnold, Brice; Bouchard, Gary; Boyce, Richard F.; Boyce, Richard M.; Callen, Alice; Campell, Marc; Curiel, Ruben; Galtier, Eric; Garofoli, Justin; Granados, Eduardo; Hastings, Jerry; Hays, Greg; Heimann, Philip; Lee, Richard W.; Milathianaki, Despina; Plummer, Lori; Schropp, Andreas; Wallace, Alex; Welch, Marc; White, William; Xing, Zhou; Yin, Jing; Young, James; Zastrau, Ulf; Lee, Hae Ja

    2015-01-01

    The LCLS beam provides revolutionary capabilities for studying the transient behavior of matter in extreme conditions. The particular strength of the Matter in Extreme Conditions instrument is that it combines the unique LCLS beam with high-power optical laser beams, and a suite of dedicated diagnostics tailored for this field of science. In this paper an overview of the beamline, the capabilities of the instrumentation, and selected highlights of experiments and commissioning results are presented. PMID:25931063

  20. [Sportsmanship and physical preparedness of junior physicians to work in extreme conditions].

    PubMed

    Timofeev, D A; Madzigon, L K

    2010-04-01

    Were examined characteristics of physical development and preparedness of physicians with different value of successfulness of activity in extreme conditions for the period of their first specialization in internship training. Was shown that to the end of study physiological resources of physicians decrease, it could have negative consequences on their activity in extreme conditions. Was made a conclusion that it's necessary to add lessons of physical preparedness, when the main attention would be paid to development of force qualities.

  1. Bias and Variance Approximations for Estimators of Extreme Quantiles

    DTIC Science & Technology

    1988-11-01

    meaningful comparison must Lake the bias as well as the variance term into account, as otherwise it would be possible to achieve very high accuracy by taking...likelihood. So far no indication has been given of the accuracy of the proposed approximations to the bias. A theoretical way to assess this is as follows...METHOD N ESTIMATED y BIAS IN qI BIAS IN q2 DIST. CRUDE BC EXACT APPROX EXACT APPROX EXACT Normal GEV 100 -.127 -.095 -.101 - .17 - .16 .40 .26 Normal GPD

  2. A scoping review of the use of elastic therapeutic tape for neck or upper extremity conditions.

    PubMed

    Taylor, Raewyn L; O'Brien, Lisa; Brown, Ted

    2014-01-01

    Scoping review. Elastic therapeutic tape is a relatively new intervention for treating a variety of injuries; however, there is little evidence to support its effectiveness for neck or upper extremity conditions. This scoping review examines current evidence on the recommended application, purpose and effectiveness of elastic therapeutic tape for treating neck or upper extremity conditions. A scoping review was conducted to examine the evidence in 14 peer-reviewed published articles that reported on the use of elastic therapeutic tape for neck or upper extremity conditions. Six studies reported statistically significant changes to pain with the use of elastic therapeutic tape. Only three studies found statistically significant changes to range of motion. Elastic therapeutic tape may play a role in reducing short-term neck and upper extremity pain, however future high quality studies that contribute to the evidence base for its use are needed. N/A. Copyright © 2014 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  3. Ensuring the consistancy of Flow Direction Curve reconstructions: the 'quantile solidarity' approach

    NASA Astrophysics Data System (ADS)

    Poncelet, Carine; Andreassian, Vazken; Oudin, Ludovic

    2015-04-01

    Flow Duration Curves (FDCs) are a hydrologic tool describing the distribution of streamflows at a catchment outlet. FDCs are usually used for calibration of hydrological models, managing water quality and classifying catchments, among others. For gauged catchments, empirical FDCs can be computed from streamflow records. For ungauged catchments, on the other hand, FDCs cannot be obtained from streamflow records and must therefore be obtained in another manner, for example through reconstructions. Regression-based reconstructions are methods relying on the evaluation of quantiles separately from catchments' attributes (climatic or physical features).The advantage of this category of methods is that it is informative about the processes and it is non-parametric. However, the large number of parameters required can cause unwanted artifacts, typically reconstructions that do not always produce increasing quantiles. In this paper we propose a new approach named Quantile Solidarity (QS), which is applied under strict proxy-basin test conditions (Klemes, 1986) to a set of 600 French catchments. Half of the catchments are considered as gauged and used to calibrate the regression and compute residuals of the regression. The QS approach consists in a three-step regionalization scheme, which first links quantile values to physical descriptors, then reduces the number of regression parameters and finally exploits the spatial correlation of the residuals. The innovation is the utilisation of the parameters continuity across the quantiles to dramatically reduce the number of parameters. The second half of catchment is used as an independent validation set over which we show that the QS approach ensures strictly growing FDC reconstructions in ungauged conditions. Reference: V. KLEMEŠ (1986) Operational testing of hydrological simulation models, Hydrological Sciences Journal, 31:1, 13-24

  4. Modeling energy expenditure in children and adolescents using quantile regression

    USDA-ARS?s Scientific Manuscript database

    Advanced mathematical models have the potential to capture the complex metabolic and physiological processes that result in energy expenditure (EE). Study objective is to apply quantile regression (QR) to predict EE and determine quantile-dependent variation in covariate effects in nonobese and obes...

  5. Matching a Distribution by Matching Quantiles Estimation

    PubMed Central

    Sgouropoulos, Nikolaos; Yao, Qiwei; Yastremiz, Claudia

    2015-01-01

    Motivated by the problem of selecting representative portfolios for backtesting counterparty credit risks, we propose a matching quantiles estimation (MQE) method for matching a target distribution by that of a linear combination of a set of random variables. An iterative procedure based on the ordinary least-squares estimation (OLS) is proposed to compute MQE. MQE can be easily modified by adding a LASSO penalty term if a sparse representation is desired, or by restricting the matching within certain range of quantiles to match a part of the target distribution. The convergence of the algorithm and the asymptotic properties of the estimation, both with or without LASSO, are established. A measure and an associated statistical test are proposed to assess the goodness-of-match. The finite sample properties are illustrated by simulation. An application in selecting a counterparty representative portfolio with a real dataset is reported. The proposed MQE also finds applications in portfolio tracking, which demonstrates the usefulness of combining MQE with LASSO. PMID:26692592

  6. Matching a Distribution by Matching Quantiles Estimation.

    PubMed

    Sgouropoulos, Nikolaos; Yao, Qiwei; Yastremiz, Claudia

    2015-04-03

    Motivated by the problem of selecting representative portfolios for backtesting counterparty credit risks, we propose a matching quantiles estimation (MQE) method for matching a target distribution by that of a linear combination of a set of random variables. An iterative procedure based on the ordinary least-squares estimation (OLS) is proposed to compute MQE. MQE can be easily modified by adding a LASSO penalty term if a sparse representation is desired, or by restricting the matching within certain range of quantiles to match a part of the target distribution. The convergence of the algorithm and the asymptotic properties of the estimation, both with or without LASSO, are established. A measure and an associated statistical test are proposed to assess the goodness-of-match. The finite sample properties are illustrated by simulation. An application in selecting a counterparty representative portfolio with a real dataset is reported. The proposed MQE also finds applications in portfolio tracking, which demonstrates the usefulness of combining MQE with LASSO.

  7. Resistance of Microorganisms to Extreme Environmental Conditions and Its Contribution to Astrobiology

    NASA Astrophysics Data System (ADS)

    Rampelotto, Pabulo Henrique

    2010-06-01

    In the last decades, substantial changes have occurred regarding what scientists consider the limits of habitable environmental conditions. For every extreme environmental condition investigated, a variety of microorganisms have shown that not only can they tolerate these conditions, but that they also often require these extreme conditions for survival. Microbes can return to life even after hundreds of millions of years. Furthermore, a variety of studies demonstrate that microorganisms can survive under extreme conditions, such as ultracentrifugation, hypervelocity, shock pressure, high temperature variations, vacuums, and different ultraviolet and ionizing radiation intensities, which simulate the conditions that microbes could experience during the ejection from one planet, the journey through space, as well as the impact in another planet. With these discoveries, our knowledge about the biosphere has grown and the putative boundaries of life have expanded. The present work examines the recent discoveries and the principal advances concerning the resistance of microorganisms to extreme environmental conditions, and analyzes its contributions to the development of the main themes of astrobiology: the origins of life, the search for extraterrestrial life, and the dispersion of life in the Universe.

  8. Quantile regression of microgeographic variation in population characteristics of an invasive vertebrate predator

    PubMed Central

    Siers, Shane R.; Savidge, Julie A.; Reed, Robert N.

    2017-01-01

    Localized ecological conditions have the potential to induce variation in population characteristics such as size distributions and body conditions. The ability to generalize the influence of ecological characteristics on such population traits may be particularly meaningful when those traits influence prospects for successful management interventions. To characterize variability in invasive Brown Treesnake population attributes within and among habitat types, we conducted systematic and seasonally-balanced surveys, collecting 100 snakes from each of 18 sites: three replicates within each of six major habitat types comprising 95% of Guam’s geographic expanse. Our study constitutes one of the most comprehensive and controlled samplings of any published snake study. Quantile regression on snake size and body condition indicated significant ecological heterogeneity, with a general trend of relative consistency of size classes and body conditions within and among scrub and Leucaena forest habitat types and more heterogeneity among ravine forest, savanna, and urban residential sites. Larger and more robust snakes were found within some savanna and urban habitat replicates, likely due to relative availability of larger prey. Compared to more homogeneous samples in the wet season, variability in size distributions and body conditions was greater during the dry season. Although there is evidence of habitat influencing Brown Treesnake populations at localized scales (e.g., the higher prevalence of larger snakes—particularly males—in savanna and urban sites), the level of variability among sites within habitat types indicates little ability to make meaningful predictions about these traits at unsampled locations. Seasonal variability within sites and habitats indicates that localized population characterization should include sampling in both wet and dry seasons. Extreme values at single replicates occasionally influenced overall habitat patterns, while pooling

  9. Infrared and Terahertz Spectroscopy of Strongly Correlated Electron Systems under Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Kimura, Shin-ichi; Okamura, Hidekazu

    2013-02-01

    Owing to its high brilliance, infrared and terahertz synchrotron radiation (IR/THz-SR) has emerged as a powerful tool for spectroscopy under extreme (i.e., technically more difficult) experimental conditions such as high pressure, high magnetic field, high spatial resolution, and a combination of these. The methodologies for pressure- and magnetic-field-dependent spectroscopy and microscopy using IR/THz-SR have advanced rapidly worldwide. By applying them to strongly correlated electron systems (SCESs), many experimental studies have been performed on their electronic structures and phonon/molecular vibration modes under extreme conditions. Here, we review the recent progress of methodologies of IR/THz-SR spectroscopy and microscopy, and the experimental results on SCESs and other systems obtained under extreme conditions.

  10. Influence of extreme ambient temperatures and anaerobic conditions on Peltigera aphthosa (L.) Willd. viability

    NASA Astrophysics Data System (ADS)

    Dyakov, M. Yu.; Insarova, I. D.; Kharabadze, D. E.; Ptushenko, V. V.; Shtaer, O. V.

    2015-11-01

    Lichen are symbiotic systems constituted by heterotrophic fungi (mycobionts) and photosynthetic microorganism (photobionts). These organisms can survive under extreme stress conditions. The aim of this work was to study the influence of low (- 70 °C) or high (+ 70 °C) temperatures, temperature fluctuations from + 70 °C to - 70 °C, and anaerobic conditions on P. aphthosa (L.) Willd. viability. None of the studied stress factors affected significantly photosynthetic and respiratory activity of the thalli. No changes in morphology or ultrastructure of the cells were revealed for both photobiont and mycobiont components after extreme temperature treatment of P. aphthosa thalli. The data show the extreme tolerance of P. aphthosa to some stress factors inherent to the space flight conditions.

  11. Extreme groundwater levels caused by extreme weather conditions - the highest ever measured groundwater levels in Middle Germany and their management

    NASA Astrophysics Data System (ADS)

    Reinstorf, Frido; Kramer, Stefanie; Koch, Thomas; Seifert, Sven; Monninkhoff, Bertram; Pfützner, Bernd

    2017-04-01

    Extreme weather conditions during the years 2009 - 2011 in combination with changes in the regional water management and possible impacts of climate change led to maximum groundwater levels in large areas of Germany in 2011. This resulted in extensive water logging, with problems especially in urban areas near rivers, where water logging produced huge problems for buildings and infrastructure. The acute situation still exists in many areas and requires the development of solution concepts. Taken the example of the Elbe-Saale-Region in the Federal State of Saxony-Anhalt, were a pilot research project was carried out, the analytical situation, the development of a management tool and the implementation of a groundwater management concept are shown. The central tool is a coupled water budget - groundwater flow model. In combination with sophisticated multi-scale parameter estimation, a high resolution groundwater level simulation was carried out. A decision support process with a very intensive stakeholder interaction combined with high resolution simulations enables the development of a management concept for extreme groundwater situations in consideration of sustainable and environmentally sound solutions mainly on the base of passive measures.

  12. Estimation of peak discharge quantiles for selected annual exceedance probabilities in northeastern Illinois

    USGS Publications Warehouse

    Over, Thomas; Saito, Riki J.; Veilleux, Andrea; Sharpe, Jennifer B.; Soong, David T.; Ishii, Audrey

    2016-06-28

    This report provides two sets of equations for estimating peak discharge quantiles at annual exceedance probabilities (AEPs) of 0.50, 0.20, 0.10, 0.04, 0.02, 0.01, 0.005, and 0.002 (recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years, respectively) for watersheds in Illinois based on annual maximum peak discharge data from 117 watersheds in and near northeastern Illinois. One set of equations was developed through a temporal analysis with a two-step least squares-quantile regression technique that measures the average effect of changes in the urbanization of the watersheds used in the study. The resulting equations can be used to adjust rural peak discharge quantiles for the effect of urbanization, and in this study the equations also were used to adjust the annual maximum peak discharges from the study watersheds to 2010 urbanization conditions.The other set of equations was developed by a spatial analysis. This analysis used generalized least-squares regression to fit the peak discharge quantiles computed from the urbanization-adjusted annual maximum peak discharges from the study watersheds to drainage-basin characteristics. The peak discharge quantiles were computed by using the Expected Moments Algorithm following the removal of potentially influential low floods defined by a multiple Grubbs-Beck test. To improve the quantile estimates, generalized skew coefficients were obtained from a newly developed regional skew model in which the skew increases with the urbanized land use fraction. The drainage-basin characteristics used as explanatory variables in the spatial analysis include drainage area, the fraction of developed land, the fraction of land with poorly drained soils or likely water, and the basin slope estimated as the ratio of the basin relief to basin perimeter.This report also provides the following: (1) examples to illustrate the use of the spatial and urbanization-adjustment equations for estimating peak discharge quantiles at

  13. The Effectiveness of Drinking and Driving Policies for Different Alcohol-Related Fatalities: A Quantile Regression Analysis

    PubMed Central

    Ying, Yung-Hsiang; Wu, Chin-Chih; Chang, Koyin

    2013-01-01

    To understand the impact of drinking and driving laws on drinking and driving fatality rates, this study explored the different effects these laws have on areas with varying severity rates for drinking and driving. Unlike previous studies, this study employed quantile regression analysis. Empirical results showed that policies based on local conditions must be used to effectively reduce drinking and driving fatality rates; that is, different measures should be adopted to target the specific conditions in various regions. For areas with low fatality rates (low quantiles), people’s habits and attitudes toward alcohol should be emphasized instead of transportation safety laws because “preemptive regulations” are more effective. For areas with high fatality rates (or high quantiles), “ex-post regulations” are more effective, and impact these areas approximately 0.01% to 0.05% more than they do areas with low fatality rates. PMID:24084673

  14. Modeling relationship between mean years of schooling and household expenditure at Central Sulawesi using constrained B-splines (COBS) in quantile regression

    NASA Astrophysics Data System (ADS)

    Hudoyo, Luhur Partomo; Andriyana, Yudhie; Handoko, Budhi

    2017-03-01

    Quantile regression illustrates the distribution of conditional variable responses to various quantile desired values. Each quantile characterizes a certain point (center or tail) of a conditional distribution. This analysis is very useful for asymmetric conditional distribution, e.g. solid at the tail of the distribution, the truncated distribution and existence of outliers. One approach nonparametric method of predicting the conditional quantile objective function is Constrained B-Splines (COBS). COBS is a smoothing technique to accommodate the addition of constraints such as monotonicity, convexity and periodicity. In this study, we will change the minimum conditional quantile objective function in COBS into a linear programming problem. Linear programming problem is defined as the problem of minimizing and maximizing a linear function subject to linear constraints. The constraints may be equalities or inequalities. This research will discuss the relationship between education (mean years of schooling) and economic (household expenditure) levels at Central Sulawesi Province in 2014 which household level data provide more systematic evidence on positive relationship. So monotonicity (increasing) constraints will be used in COBS quantile regression model.

  15. Estimation of the uncertainty in water level forecasts at ungauged locations using Quantile Regression

    NASA Astrophysics Data System (ADS)

    Roscoe, K. L.; Weerts, A. H.

    2012-04-01

    Water level predictions in rivers are used by operational managers to make water management decisions. Such decisions can concern water routing in times of drought, operation of weirs, and actions for flood protection, such as evacuation. Understanding the uncertainty in the predictions can help managers make better-informed decisions. Conditional Quantile Regression is a method that can be used to determine the uncertainty in forecasted water levels by providing an estimate of the probability density function of the error in the prediction conditional on the forecasted water level. To derive this relationship, a series of forecasts and errors in the forecasts (residuals) are required. Thus, conditional quantile regressions can be derived for locations where both observations and forecasts are available. However, 1D-hydraulic models that are used for operational forecasting produce forecasts at intermediate points where no measurements are available but for which predictive uncertainty estimates are also desired for decision making. The objective of our study is to test if interpolation methods can be used to adequately estimate conditional quantile regressions at these in-between locations. For this purpose, five years of hindcasts were used at seven stations along the IJssel River in the Netherlands. Residuals in water level hindcasts were interpolated at the five in-between lying stations. The interpolation was based solely on distance and the interpolated residuals were compared to the measured residuals at stations at the in-between locations. The resulting interpolated residuals estimated the measured residuals well, especially for longer lead times. Quantile regression was then carried out using the series of forecasts and interpolated residuals at the in-between stations. The interpolated quantile regressions were compared with regressions calibrated using the actual residuals at the in-between stations. Results show that even a simple interpolation based

  16. Regional flood frequency analysis using spatial proximity and basin characteristics: Quantile regression vs. parameter regression technique

    NASA Astrophysics Data System (ADS)

    Ahn, Kuk-Hyun; Palmer, Richard

    2016-09-01

    Despite wide use of regression-based regional flood frequency analysis (RFFA) methods, the majority are based on either ordinary least squares (OLS) or generalized least squares (GLS). This paper proposes 'spatial proximity' based RFFA methods using the spatial lagged model (SLM) and spatial error model (SEM). The proposed methods are represented by two frameworks: the quantile regression technique (QRT) and parameter regression technique (PRT). The QRT develops prediction equations for flooding quantiles in average recurrence intervals (ARIs) of 2, 5, 10, 20, and 100 years whereas the PRT provides prediction of three parameters for the selected distribution. The proposed methods are tested using data incorporating 30 basin characteristics from 237 basins in Northeastern United States. Results show that generalized extreme value (GEV) distribution properly represents flood frequencies in the study gages. Also, basin area, stream network, and precipitation seasonality are found to be the most effective explanatory variables in prediction modeling by the QRT and PRT. 'Spatial proximity' based RFFA methods provide reliable flood quantile estimates compared to simpler methods. Compared to the QRT, the PRT may be recommended due to its accuracy and computational simplicity. The results presented in this paper may serve as one possible guidepost for hydrologists interested in flood analysis at ungaged sites.

  17. Model averaging quantiles from data censored by a limit of detection.

    PubMed

    Nysen, Ruth; Faes, Christel; Ferrari, Pietro; Verger, Philippe; Aerts, Marc

    2016-03-01

    In chemical risk assessment, it is important to determine the quantiles of the distribution of concentration data. The selection of an appropriate distribution and the estimation of particular quantiles of interest are largely hindered by the omnipresence of observations below the limit of detection, leading to left-censored data. The log-normal distribution is a common choice, but this distribution is not the only possibility and alternatives should be considered as well. Here, we focus on several distributions that are related to the log-normal distribution or that are seminonparametric extensions of the log-normal distribution. Whereas previous work focused on the estimation of the cumulative distribution function, our interest here goes to the estimation of quantiles, particularly in the left tail of the distribution where most of the left-censored data are located. Two different model averaged quantile estimators are defined and compared for different families of candidate models. The models and methods of selection and averaging are further investigated through simulations and illustrated on data of cadmium concentration in food products. The approach is extended to include covariates and to deal with uncertainty about the values of the limit of detection. These extensions are illustrated with (134) cesium measurements from Fukushima Prefecture, Japan. We can conclude that averaged models do achieve good performance characteristics in case no useful prior knowledge about the true distribution is available; that there is no structural difference in the performance of the direct and indirect method; and that, not surprisingly, only the true or closely approximating model can deal with extremely high percentages of censoring.

  18. Comparison of Extreme Pressure Additive Treat Rates in Soybean and Mineral Oils Under Boundary Lubrication Conditions

    USDA-ARS?s Scientific Manuscript database

    Traditionally, it is considered that, under boundary lubrication conditions, the reduction in friction and wear is mostly dependent on Extreme Pressure (EP) additives, rather than the basestock. However, several studies indicate that vegetable oils also contribute to the lubricity under this regime...

  19. The Extreme Male Brain Theory and Gender Role Behaviour in Persons with an Autism Spectrum Condition

    ERIC Educational Resources Information Center

    Stauder, J. E. A.; Cornet, L. J. M.; Ponds, R. W. H. M.

    2011-01-01

    According to the Extreme Male Brain theory persons with autism possess masculinised cognitive traits. In this study masculinisation of gender role behaviour is evaluated in 25 persons with an autism spectrum condition (ASC) and matched controls with gender role behaviour as part of a shortened version of the Minnesota Multiphasic Personality…

  20. Special Features of the Carbonitriding of Parts of Instrument Bearings Designed for Extreme Service Conditions

    NASA Astrophysics Data System (ADS)

    Smirnov, A. E.; Shevchenko, S. Yu.; Shchipunov, V. S.; Kunyaev, V. E.; Seval'nev, G. S.

    2016-09-01

    A study is made of complexly alloyed steel 8Kh4V9F2-Sh, which is used for fabricating parts of engineering bearings operating under extreme conditions. Vacuum processes are shown to be preferable to gas carburizing for hardening the races of precision bearings. Vacuum carburizing is shown to be an effective technique for forming quality diffusion layers.

  1. The Extreme Male Brain Theory and Gender Role Behaviour in Persons with an Autism Spectrum Condition

    ERIC Educational Resources Information Center

    Stauder, J. E. A.; Cornet, L. J. M.; Ponds, R. W. H. M.

    2011-01-01

    According to the Extreme Male Brain theory persons with autism possess masculinised cognitive traits. In this study masculinisation of gender role behaviour is evaluated in 25 persons with an autism spectrum condition (ASC) and matched controls with gender role behaviour as part of a shortened version of the Minnesota Multiphasic Personality…

  2. Atmospheric conditions and weather regimes associated with extreme winter dry spells over the Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Raymond, Florian; Ullmann, Albin; Camberlin, Pierre; Oueslati, Boutheina; Drobinski, Philippe

    2017-09-01

    Very long dry spell events occurring during winter are natural hazards to which the Mediterranean region is extremely vulnerable, because they can lead numerous impacts for environment and society. Four dry spell patterns have been identified in a previous work. Identifying the main associated atmospheric conditions controlling the dry spell patterns is key to better understand their dynamics and their evolution in a changing climate. Except for the Levant region, the dry spells are generally associated with anticyclonic blocking conditions located about 1000 km to the Northwest of the affected area. These anticyclonic conditions are favourable to dry spell occurrence as they are associated with subsidence of cold and dry air coming from boreal latitudes which bring low amount of water vapour and non saturated air masses, leading to clear sky and absence of precipitation. These extreme dry spells are also partly related to the classical four Euro-Atlantic weather regimes are: the two phases of the North Atlantic Oscillation, the Scandinavian "blocking" or "East-Atlantic", and the "Atlantic ridge". Only the The "East-Atlantic", "Atlantic ridge" and the positive phase of the North Atlantic Oscillation are frequently associated with extremes dry spells over the Mediterranean basin but they do not impact the four dry spell patterns equally. Finally long sequences of those weather regimes are more favourable to extreme dry spells than short sequences. These long sequences are associated with the favourable prolonged and reinforced anticyclonic conditions

  3. Role of Water in the Selection of Stable Proteins at Ambient and Extreme Thermodynamic Conditions

    NASA Astrophysics Data System (ADS)

    Bianco, Valentino; Franzese, Giancarlo; Dellago, Christoph; Coluzza, Ivan

    2017-04-01

    Proteins that are functional at ambient conditions do not necessarily work at extreme conditions of temperature T and pressure P . Furthermore, there are limits of T and P above which no protein has a stable functional state. Here, we show that these limits and the selection mechanisms for working proteins depend on how the properties of the surrounding water change with T and P . We find that proteins selected at high T are superstable and are characterized by a nonextreme segregation of a hydrophilic surface and a hydrophobic core. Surprisingly, a larger segregation reduces the stability range in T and P . Our computer simulations, based on a new protein design protocol, explain the hydropathy profile of proteins as a consequence of a selection process influenced by water. Our results, potentially useful for engineering proteins and drugs working far from ambient conditions, offer an alternative rationale to the evolutionary action exerted by the environment in extreme conditions.

  4. Statistical analysis of extreme river flows

    NASA Astrophysics Data System (ADS)

    Mateus, Ayana; Caeiro, Frederico; Gomes, Dora Prata; Sequeira, Inês J.

    2016-12-01

    Floods are recurrent events that can have a catastrophic impact. In this work we are interested in the analysis of a data set of gauged daily flows from the Whiteadder Water river, Scotland. Using statistic techniques based on extreme value theory, we estimate several extreme value parameters, including extreme quantiles and return periods of high levels.

  5. Matter under extreme conditions probed by a seeded free-electron-laser

    SciTech Connect

    Bencivenga, F.; Principi, E.; Cucini, R.; Danailov, M. B.; Demidovich, A.; D’Amico, F.; Di Fonzo, S.; Gessini, A.; Kurdi, N.; Mahne, N.; Raimondi, L.; Zangrando, M.; Masciovecchio, C.; Giangrisostomi, E.; Battistoni, A.; Svetina, C.; Di Cicco, A.; Gunnella, R.; Hatada, K.; Filipponi, A.; and others

    2015-08-17

    FERMI is the first user dedicated seeded free-electron-laser (FEL) working in the extreme ultraviolet (XUV) and soft x-ray range. The EIS-TIMEX experimental end-station was availabe to external users since from the beginning of the user operation of the facility, in Dicember 2012. EIS-TIMEX has been conceived to exploit the unique properties of the FERMI source to study matter under extreme and metastable thermodynamic conditions. We hereby report on its basic parameters and applications, which includes very low jitter (i.e., high time resolution) pump-probe measurements.

  6. Disease mapping via negative binomial regression M-quantiles.

    PubMed

    Chambers, Ray; Dreassi, Emanuela; Salvati, Nicola

    2014-11-30

    We introduce a semi-parametric approach to ecological regression for disease mapping, based on modelling the regression M-quantiles of a negative binomial variable. The proposed method is robust to outliers in the model covariates, including those due to measurement error, and can account for both spatial heterogeneity and spatial clustering. A simulation experiment based on the well-known Scottish lip cancer data set is used to compare the M-quantile modelling approach with a disease mapping approach based on a random effects model. This suggests that the M-quantile approach leads to predicted relative risks with smaller root mean square error. The paper concludes with an illustrative application of the M-quantile approach, mapping low birth weight incidence data for English Local Authority Districts for the years 2005-2010.

  7. Preparation of monolithic silica-chitin composite under extreme biomimetic conditions.

    PubMed

    Bazhenov, Vasilii V; Wysokowski, Marcin; Petrenko, Iaroslav; Stawski, Dawid; Sapozhnikov, Philipp; Born, René; Stelling, Allison L; Kaiser, Sabine; Jesionowski, Teofil

    2015-05-01

    Chitin is a widespread renewable biopolymer that is extensively distributed in the natural world. The high thermal stability of chitin provides an opportunity to develop novel inorganic-organic composites under hydrothermal synthesis conditions in vitro. For the first time, in this work we prepared monolithic silica-chitin composite under extreme biomimetic conditions (80°C and pH 1.5) using three dimensional chitinous matrices isolated from the marine sponge Aplysina cauliformis. The resulting material was studied using light and fluorescence microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy. A mechanism for the silica-chitin interaction after exposure to these hydrothermal conditions is proposed and discussed.

  8. [Experimental evaluation of actoprotective activity of nitrogen-containing heterocyclic compounds derivatives in extreme conditions].

    PubMed

    Tsublova, E G; Ivanova, T G; Ivanova, T N; Iasnetsov, V V

    2013-07-01

    In experiments on nonlinear male mice the ability of new derivatives of nitrogen-containing heterocyclic compounds to increase the physical working capacity in conditions of hyperthermia, hypothermia and acute normobaric hypoxia and hypercapnia has been investigated. It is established, that pyridine derivative IBHF-11 has more expressed positive action in the said conditions. It provided increase of the working capacity of animals at all kinds of extreme influence, and the value of positive action was comparable, and in conditions of acute normobaric hypoxia and hypercapnia exceeded those at the reference products bemitil and bromantan.

  9. [Effect of Bergenia crassifolia extract on specific immune response parameters under extremal conditions].

    PubMed

    Churin, A A; Masnaia, N V; Sherstoboev, E Yu; Suslov, N I

    2005-01-01

    The influence of a dry extract from Bergenia crassifolia (Fritsch) on the specific immune response parameters was studied under extremal conditions of model immunodepressive states induced by immobilization stress or cyclophosphamide injections. The drug produced normalizing effect on the content of antibody-forming cells in the spleen of experimental mice under the conditions of humoral response stimulation by antigen and in both immunodepression models. The bergenia extract decreases expression of inflammatory processes under delayed hypersensitivity reaction conditions, by preventing the accumulation of T-lymphocytes in the inflammation focus and reducing the ability of cells to produce anti-inflammatory cytokines.

  10. Deterioration modeling for condition assessment of flexible pavements considering extreme weather events

    NASA Astrophysics Data System (ADS)

    Hashemi Tari, Yasamin; Shahini Shamsabadi, Salar; Birken, Ralf; Wang, Ming

    2015-04-01

    Accurate pavement management systems are essential for states' Department Of Transportation and roadway agencies to plan for cost-effective maintenance and repair (M and R) strategies. Pavement deterioration model is an imperative component of any pavement management system since the future budget and M and R plans would be developed based on the predicted pavement performance measures. It is crucial for the pavement deterioration models to consider the factors that significantly aggravate the pavement condition. While many studies have highlighted the impact of different environmental, load, and pavement's structure on the life cycle of the pavement, effect of extreme weather events such as Floods and Snow Storms have often been overlooked. In this study, a pavement deterioration model is proposed which would consider the effect of traffic loads, climate conditions, and extreme weather events. Climate, load and performance data has been compiled for over twenty years and for eight states using the Long Term Pavement Performance (LTPP) and National Oceanic and Atmospheric Administration (NOAA) databases. A stepwise regression approach is undertaken to quantify the effect of the extreme weather events, along with other influential factors on pavement performance in terms of International Roughness Index (IRI). Final results rendered more than 90% correlation with the quantified impact values of extreme weather events.

  11. Distribution patterns of terricolous and saxicolous lichens in extreme desert conditions

    NASA Astrophysics Data System (ADS)

    Temina, M.

    2012-04-01

    The investigation of biodiversity in stressful habitats is of great interest because it elucidates relationships between organisms and their environment, as well as revealing the mechanisms of their survival and adaptation to extreme conditions. Deserts represent such stressful habitats where harsh climate and limited resources greatly influence the formation of biota. In order to understand the link between microscale environmental variability in extreme arid conditions and lichen biodiversity patterns, we conducted the present study. For this purpose, the structure and distribution of lichen communities on soil and cobbles at six stations at "Evolution Canyon" III (EC III), Nahal Shaharut, in the extreme southern Negev, Israel, were examined. The opposite slopes of the canyon represented specific ecological niches characterized by sharply different microclimatic conditions. The following characteristics of lichen communities were studied: species richness, systematic diversity, biogeographical elements, frequencies and distribution of species, their morphological and anatomical characteristics, reproductive strategy, and ecological peculiarities. In the research site three environmental variables were evaluated: soil moisture, and temperatures of soil and cobbles. The Canonical Correspondence Analysis was used to study the influence of these ecological variables on the distribution of lichen species. The lichen diversity of EC III was very poor and comprised 12 species (3 cyanoliches on soil vs. 9 phycolichens on cobbles). Most of them belong to a specific group of arid endemic elements, adapted to survive in extreme arid conditions in the deserts of the Levant. The harsh desert conditions of the canyon negatively influence the reproductive ability of lichens. This influence is expressed in the decreased sizes of fruit bodies in some species, and the frequent occurrence of sterile specimens among lichens found in the canyon. A comparative analysis of structure

  12. Quantitative risk assessment of the effects of drought on extreme temperature in eastern China

    NASA Astrophysics Data System (ADS)

    Hao, Zengchao; Hao, Fanghua; Singh, Vijay P.; Ouyang, Wei

    2017-09-01

    Hot extremes may lead to disastrous impacts on human health and agricultural production. Previous studies have revealed the feedback between drought and hot extremes in large regions of eastern China, while quantifying the impact of antecedent drought on hot extremes has been limited. This study aims at quantitatively assessing the risk of extreme temperature conditioned on the antecedent drought condition represented by Standardized Precipitation Index (SPI) during summer time in eastern China. A copula-based model is proposed to construct the joint probability distribution of extreme temperature and drought based on 6 month SPI (SPI6). Accordingly, the conditional probability distribution is employed to quantify impacts of antecedent dry (and wet) conditions on the exceedance probability of extreme temperature. Results show that the likelihood of extreme temperature exceeding high quantiles is higher given antecedent dry conditions than that given antecedent wet conditions in large regions from southwestern to northeastern China. Specifically, the conditional probability difference of temperature exceeding 80th percentile given SPI6 lower than or equal to -0.5 and SPI6 higher than 0.5 is around 0.2-0.3. The case study of the 2006 summer hot extremes and drought in Sichuan and Chongqing region shows that the conditional return period of extreme temperature conditioned on antecedent drought is around 5-50 years shorter than univariate return period. These results quantify the impact of antecedent drought on subsequent extreme temperature and highlight the important role of antecedent drought in intensifying hot extremes in these regions.

  13. Dynamic response analysis of a heavy commercial vehicle subjected to extreme road operating conditions

    NASA Astrophysics Data System (ADS)

    Chinnaraj, K.; Mangalaramanan, S. P.; Lakshmana Rao, C.

    2009-08-01

    Wheel excitations measured on a heavy commercial vehicle by driving it through extreme road operating conditions, are considered as inputs to perform dynamic response analysis in a simulated laboratory and computational environment. From initial modal analysis results using finite elements, critical vehicle frame rail locations are identified for dynamic laboratory strain measurements on a six poster road load simulator that employs dynamic wheel excitations as input. Dynamic stresses calculated from measured strain values are then compared with computationally obtained stress results on each of these locations. This study also points out all geometric locations and vibration modes that may affect the design behavior of the frame members under extreme road operating conditions. The results obtained from this work can be considered for further fatigue life prediction and design optimization of chassis frame rail assembly.

  14. In-situ transmission electron microscopy growth of nanoparticles under extreme conditions

    SciTech Connect

    Luce, F. P.; Azevedo, G. de M.; Baptista, D. L.; Zawislak, F. C.; Oliviero, E.; Fichtner, P. F. P.

    2016-01-21

    The formation and time resolved behavior of individual Pb nanoparticles embedded in silica have been studied by in-situ transmission electron microscopy observations at high temperatures (400–1100 °C) and under 200 keV electron irradiation. It is shown that under such extreme conditions, nanoparticles can migrate at long distances presenting a Brownian-like behavior and eventually coalesce. The particle migration phenomenon is discussed considering the influence of the thermal energy and the electron irradiation effects on the atomic diffusion process which is shown to control particle migration. These results and comparison with ex-situ experiments tackle the stability and the microstructure evolution of nanoparticles systems under extreme conditions. It elucidates on the effects of energetic particle irradiation-annealing treatments either as a tool or as a detrimental issue that could hamper their long-term applications in radiation-harsh environments such as in space or nuclear sectors.

  15. Computational approaches to investigate how biological macromolecules can be protected in extreme conditions.

    PubMed

    Dashnau, J L; Vanderkooi, J M

    2007-01-01

    Water is required to hydrate molecules, but under cold conditions water freezes and under dehydrating conditions water evaporates--thus presenting a dilemma for organisms that live in extreme environments. Organisms have developed various strategies for protection against extreme temperatures and dehydration. In this review, we describe how the interaction of water and 2 natural cryoprotectants, namely glycerol and sugars, can be studied at the molecular level. Techniques using infrared spectroscopy and computation are described. In the case of glycerol, H-bonding of water to the OH groups of glycerol limits the amount of water available to form ice and prevents crystallization at low temperatures. For aldohexopyranose sugars, the different isomeric forms have different water H-bonding networks, which are consistent with isomeric-dependent activities. By studying the strategies used in nature, derivatives for use in food preservation can be more readily developed.

  16. Improvised purification methods for obtaining individual drinking water supply under war and extreme shortage conditions.

    PubMed

    Kozlicic, A; Hadzic, A; Bevanda, H

    1994-01-01

    Supplying an adequate amount of drinking water to a population is a complex problem that becomes an extremely difficult task in war conditions. In this paper, several simple methods for obtaining individual supplies of drinking water by filtration of atmospheric water with common household items are reported. Samples of atmospheric water (rain and snow) were collected, filtered, and analyzed for bacteriological and chemical content. The ability of commonly available household materials (newspaper, filter paper, gauze, cotton, and white cotton cloth) to filter water from the environmental sources was compared. According to chemical and biological analysis, the best results were obtained by filtering melted snow from the ground through white cotton cloth. Atmospheric water collected during war or in extreme shortage conditions can be purified with simple improvised filtering techniques and, if chlorinated, used as an emergency potable water source.

  17. Relationship between Urbanization and Cancer Incidence in Iran Using Quantile Regression.

    PubMed

    Momenyan, Somayeh; Sadeghifar, Majid; Sarvi, Fatemeh; Khodadost, Mahmoud; Mosavi-Jarrahi, Alireza; Ghaffari, Mohammad Ebrahim; Sekhavati, Eghbal

    2016-01-01

    Quantile regression is an efficient method for predicting and estimating the relationship between explanatory variables and percentile points of the response distribution, particularly for extreme percentiles of the distribution. To study the relationship between urbanization and cancer morbidity, we here applied quantile regression. This cross-sectional study was conducted for 9 cancers in 345 cities in 2007 in Iran. Data were obtained from the Ministry of Health and Medical Education and the relationship between urbanization and cancer morbidity was investigated using quantile regression and least square regression. Fitting models were compared using AIC criteria. R (3.0.1) software and the Quantreg package were used for statistical analysis. With the quantile regression model all percentiles for breast, colorectal, prostate, lung and pancreas cancers demonstrated increasing incidence rate with urbanization. The maximum increase for breast cancer was in the 90th percentile (β=0.13, p-value<0.001), for colorectal cancer was in the 75th percentile (β=0.048, p-value<0.001), for prostate cancer the 95th percentile (β=0.55, p-value<0.001), for lung cancer was in 95th percentile (β=0.52, p-value=0.006), for pancreas cancer was in 10th percentile (β=0.011, p-value<0.001). For gastric, esophageal and skin cancers, with increasing urbanization, the incidence rate was decreased. The maximum decrease for gastric cancer was in the 90th percentile(β=0.003, p-value<0.001), for esophageal cancer the 95th (β=0.04, p-value=0.4) and for skin cancer also the 95th (β=0.145, p-value=0.071). The AIC showed that for upper percentiles, the fitting of quantile regression was better than least square regression. According to the results of this study, the significant impact of urbanization on cancer morbidity requirs more effort and planning by policymakers and administrators in order to reduce risk factors such as pollution in urban areas and ensure proper nutrition

  18. A hierarchical Bayesian GEV model for improving local and regional flood quantile estimates

    NASA Astrophysics Data System (ADS)

    Lima, Carlos H. R.; Lall, Upmanu; Troy, Tara; Devineni, Naresh

    2016-10-01

    We estimate local and regional Generalized Extreme Value (GEV) distribution parameters for flood frequency analysis in a multilevel, hierarchical Bayesian framework, to explicitly model and reduce uncertainties. As prior information for the model, we assume that the GEV location and scale parameters for each site come from independent log-normal distributions, whose mean parameter scales with the drainage area. From empirical and theoretical arguments, the shape parameter for each site is shrunk towards a common mean. Non-informative prior distributions are assumed for the hyperparameters and the MCMC method is used to sample from the joint posterior distribution. The model is tested using annual maximum series from 20 streamflow gauges located in an 83,000 km2 flood prone basin in Southeast Brazil. The results show a significant reduction of uncertainty estimates of flood quantile estimates over the traditional GEV model, particularly for sites with shorter records. For return periods within the range of the data (around 50 years), the Bayesian credible intervals for the flood quantiles tend to be narrower than the classical confidence limits based on the delta method. As the return period increases beyond the range of the data, the confidence limits from the delta method become unreliable and the Bayesian credible intervals provide a way to estimate satisfactory confidence bands for the flood quantiles considering parameter uncertainties and regional information. In order to evaluate the applicability of the proposed hierarchical Bayesian model for regional flood frequency analysis, we estimate flood quantiles for three randomly chosen out-of-sample sites and compare with classical estimates using the index flood method. The posterior distributions of the scaling law coefficients are used to define the predictive distributions of the GEV location and scale parameters for the out-of-sample sites given only their drainage areas and the posterior distribution of the

  19. Straw Mulching Reduces the Harmful Effects of Extreme Hydrological and Temperature Conditions in Citrus Orchards

    PubMed Central

    Liu, Yi; Wang, Jing; Liu, Dongbi; Li, Zhiguo; Zhang, Guoshi; Tao, Yong; Xie, Juan; Pan, Junfeng; Chen, Fang

    2014-01-01

    Extreme weather conditions with negative impacts can strongly affect agricultural production. In the Danjiangkou reservoir area, citrus yields were greatly influenced by cold weather conditions and drought stress in 2011. Soil straw mulching (SM) practices have a major effect on soil water and thermal regimes. A two-year field experiment was conducted to evaluate whether the SM practices can help achieve favorable citrus fruit yields. Results showed that the annual total runoff was significantly (P<0.05) reduced with SM as compared to the control (CK). Correspondingly, mean soil water storage in the top 100 cm of the soil profile was increased in the SM as compared to the CK treatment. However, this result was significant only in the dry season (Jan to Mar), and not in the wet season (Jul to Sep) for both years. Interestingly, the SM treatment did not significantly increase citrus fruit yield in 2010 but did so in 2011, when the citrus crop was completely destroyed (zero fruit yield) in the CK treatment plot due to extremely low temperatures during the citrus overwintering stage. The mulch probably acted as an insulator, resulting in smaller fluctuations in soil temperature in the SM than in the CK treatment. The results suggested that the small effects on soil water and temperature changes created by surface mulch had limited impact on citrus fruit yield in a normal year (e.g., in 2010). However, SM practices can positively impact citrus fruit yield in extreme weather conditions. PMID:24489844

  20. Realtime Monitoring of the Extreme Oceanic Conditions in the Kangjin Bay, South Sea, Korea

    NASA Astrophysics Data System (ADS)

    Ro, Y.; Jung, K.

    2006-05-01

    Realtime(RT) monitoring system for the oceanic state variables was developed and has been operating since April, 2004 in the Kangjin Bay, South Sea, Korea shown. The RT production of data stream and display on the Internet web page are made possible in continuous functions of various system elements. Detailed technical information for the RT monitoring system can be referred to Ro et al. (2004). The water quality parameters, current and meteorological conditions are continuously monitored with very high sampling resolution (10 min.) throughout the year and are being published on the Internet web pages (http://oceaninfo.co.kr/kangjin). The research project encompass several important subjects focusing on the extreme oceanic conditions such as very cold water mass formation during the wintertime cold outbreak, highly diluted sea water during the dam water discharge in the summertime monsoon and the subsequent formation of the hypoxia in the shallow Kangjin Bay. These are the typical extreme events captured possibly by the RT monitoring system, without which could never have been observed and understood. These extreme conditions would exert dramatic ecological impact to the local aqua-culture ecology. This study would elucidate the series of physico-chemical processes and its implication of the local eco-system. To understand the complicated processes, various research tools have been employed such as numerical modeling of tidal circulation, density-driven current, water-quality and formation of hypoxia, time series analyses of various water quality properties including multi-variate correlation.

  1. Straw mulching reduces the harmful effects of extreme hydrological and temperature conditions in citrus orchards.

    PubMed

    Liu, Yi; Wang, Jing; Liu, Dongbi; Li, Zhiguo; Zhang, Guoshi; Tao, Yong; Xie, Juan; Pan, Junfeng; Chen, Fang

    2014-01-01

    Extreme weather conditions with negative impacts can strongly affect agricultural production. In the Danjiangkou reservoir area, citrus yields were greatly influenced by cold weather conditions and drought stress in 2011. Soil straw mulching (SM) practices have a major effect on soil water and thermal regimes. A two-year field experiment was conducted to evaluate whether the SM practices can help achieve favorable citrus fruit yields. Results showed that the annual total runoff was significantly (P<0.05) reduced with SM as compared to the control (CK). Correspondingly, mean soil water storage in the top 100 cm of the soil profile was increased in the SM as compared to the CK treatment. However, this result was significant only in the dry season (Jan to Mar), and not in the wet season (Jul to Sep) for both years. Interestingly, the SM treatment did not significantly increase citrus fruit yield in 2010 but did so in 2011, when the citrus crop was completely destroyed (zero fruit yield) in the CK treatment plot due to extremely low temperatures during the citrus overwintering stage. The mulch probably acted as an insulator, resulting in smaller fluctuations in soil temperature in the SM than in the CK treatment. The results suggested that the small effects on soil water and temperature changes created by surface mulch had limited impact on citrus fruit yield in a normal year (e.g., in 2010). However, SM practices can positively impact citrus fruit yield in extreme weather conditions.

  2. Extreme conditions over Europe and North America: role of the Atlantic Multidecadal Variability

    NASA Astrophysics Data System (ADS)

    Ruprich-Robert, Yohan; Msadek, Rym; Delworth, Tom

    2016-04-01

    The Atlantic Multidecadal Variability (AMV) is the result and possibly the source of marked modulations of the climate over many areas of the globe. For instance, the relatively warm and dry climate of North America throughout the 30-yr interval of 1931-60, during which the Dust Bowl and the 1950's drought occurred, has been linked to the concomitant warm phase of the AMV. During this period relative warm and wet conditions prevailed over Europe. After 1960, the Atlantic began to cool, and for almost three decades the North American climate turned wetter and cooler whereas Europe experienced cooler and dryer conditions. However, the shortness of the historical observations compared to the AMV period suggested by longer proxy (~60-80yr) does not allow to firmly conclude on the causal effect of the AMV. We use a model approach to isolate the causal role of the AMV on the occurrence of extreme events over Europe and North America. We present experiments based on two GFDL global climate models, a low resolution version, CM2.1 and a higher resolution model for the atmospheric component, FLOR. In both model experiments sea surface temperatures in the North Atlantic sector are restored to the observed AMV pattern, while the other basins are left fully coupled. In order to explore and robustly isolate the AMV impacts on extreme events, we use large ensemble simulations (100 members for CM2.1 and 50 for FLOR) that we run for 20 years. We find that a positive phase of the AMV increases the frequency of occurrence of drought over North America and of extremely cold/warm conditions over Northern/Central Europe during winter/summer. Interestingly, we find that the AMV impacts on these extreme conditions are modulated by the Pacific response to the AMV itself. Members that develop a weak Pacific response show more extreme events over Europe whereas those that develop a strong Pacific response show more extreme events over North America.

  3. Extreme Conditions Over Europe and North America: Role of the Atlantic Multidecadal Variability

    NASA Astrophysics Data System (ADS)

    Ruprich-Robert, Y.; Msadek, R.; Delworth, T. L.

    2016-02-01

    The Atlantic Multidecadal Variability (AMV) is associated with, and possibly the source of, marked modulations of the climate over many areas of the globe. For instance, the relatively warm and dry climate of North America throughout the 30-yr interval of 1931-60, during which the Dust Bowl and the 1950's drought occurred, has been linked to the concomitant warm phase of the AMV. During this period relative warm and wet conditions prevailed over Europe. After 1960, the Atlantic began to cool, and for almost three decades the North American climate turned wetter and cooler whereas Europe experienced cooler and dryer conditions. However, the shortness of the historical observations compared to the AMV period ( 60-80yr) does not allow to firmly conclude on the causal effect of the AMV. We use a model approach to isolate the causal role of the AMV on the occurrence of extreme events over Europe and North America. We present experiments based on two GFDL global climate models, a low resolution version, CM2.1 and a higher resolution model for the atmospheric component, FLOR. In both model experiments sea surface temperatures in the North Atlantic sector are restored to the observed AMV pattern, while the other basins are left fully coupled. In order to explore and robustly isolate the AMV impacts on extreme events, we use large ensemble simulations (100 members for CM2.1 and 50 for FLOR) that we run for 20 years. We find that a positive phase of the AMV increases the frequency of occurrence of drought over North America and of extremely cold/warm conditions over Europe during winter/summer. Interestingly, we find that the AMV impacts on these extreme conditions are modulated by the Pacific response to the AMV itself. Members that develop a weak Pacific response show more extreme events over Europe whereas those that develop a strong Pacific response show more extreme events over North America. By comparing the two model results, we highlight the importance of well

  4. Prediction intervals for future BMI values of individual children: a non-parametric approach by quantile boosting.

    PubMed

    Mayr, Andreas; Hothorn, Torsten; Fenske, Nora

    2012-01-25

    The construction of prediction intervals (PIs) for future body mass index (BMI) values of individual children based on a recent German birth cohort study with n = 2007 children is problematic for standard parametric approaches, as the BMI distribution in childhood is typically skewed depending on age. We avoid distributional assumptions by directly modelling the borders of PIs by additive quantile regression, estimated by boosting. We point out the concept of conditional coverage to prove the accuracy of PIs. As conditional coverage can hardly be evaluated in practical applications, we conduct a simulation study before fitting child- and covariate-specific PIs for future BMI values and BMI patterns for the present data. The results of our simulation study suggest that PIs fitted by quantile boosting cover future observations with the predefined coverage probability and outperform the benchmark approach. For the prediction of future BMI values, quantile boosting automatically selects informative covariates and adapts to the age-specific skewness of the BMI distribution. The lengths of the estimated PIs are child-specific and increase, as expected, with the age of the child. Quantile boosting is a promising approach to construct PIs with correct conditional coverage in a non-parametric way. It is in particular suitable for the prediction of BMI patterns depending on covariates, since it provides an interpretable predictor structure, inherent variable selection properties and can even account for longitudinal data structures.

  5. Modelling hydrological extremes under non-stationary conditions using climate covariates

    NASA Astrophysics Data System (ADS)

    Vasiliades, Lampros; Galiatsatou, Panagiota; Loukas, Athanasios

    2013-04-01

    Extreme value theory is a probabilistic theory that can interpret the future probabilities of occurrence of extreme events (e.g. extreme precipitation and streamflow) using past observed records. Traditionally, extreme value theory requires the assumption of temporal stationarity. This assumption implies that the historical patterns of recurrence of extreme events are static over time. However, the hydroclimatic system is nonstationary on time scales that are relevant to extreme value analysis, due to human-mediated and natural environmental change. In this study the generalized extreme value (GEV) distribution is used to assess nonstationarity in annual maximum daily rainfall and streamflow timeseries at selected meteorological and hydrometric stations in Greece and Cyprus. The GEV distribution parameters (location, scale, and shape) are specified as functions of time-varying covariates and estimated using the conditional density network (CDN) as proposed by Cannon (2010). The CDN is a probabilistic extension of the multilayer perceptron neural network. Model parameters are estimated via the generalized maximum likelihood (GML) approach using the quasi-Newton BFGS optimization algorithm, and the appropriate GEV-CDN model architecture for the selected meteorological and hydrometric stations is selected by fitting increasingly complicated models and choosing the one that minimizes the Akaike information criterion with small sample size correction. For all case studies in Greece and Cyprus different formulations are tested with combinational cases of stationary and nonstationary parameters of the GEV distribution, linear and non-linear architecture of the CDN and combinations of the input climatic covariates. Climatic indices such as the Southern Oscillation Index (SOI), which describes atmospheric circulation in the eastern tropical pacific related to El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) index that varies on an interdecadal

  6. Analysis of extreme summers and prior late winter/spring conditions in central Europe

    NASA Astrophysics Data System (ADS)

    Träger-Chatterjee, C.; Müller, R. W.; Bendix, J.

    2013-05-01

    Drought and heat waves during summer in mid-latitudes are a serious threat to human health and agriculture and have negative impacts on the infrastructure, such as problems in energy supply. The appearance of such extreme events is expected to increase with the progress of global warming. A better understanding of the development of extremely hot and dry summers and the identification of possible precursors could help improve existing seasonal forecasts in this regard, and could possibly lead to the development of early warning methods. The development of extremely hot and dry summer seasons in central Europe is attributed to a combined effect of the dominance of anticyclonic weather regimes and soil moisture-atmosphere interactions. The atmospheric circulation largely determines the amount of solar irradiation and the amount of precipitation in an area. These two variables are themselves major factors controlling the soil moisture. Thus, solar irradiation and precipitation are used as proxies to analyse extreme sunny and dry late winter/spring and summer seasons for the period 1958-2011 in Germany and adjacent areas. For this purpose, solar irradiation data from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis dataset, as well as remote sensing data are used. Precipitation data are taken from the Global Precipitation Climatology Project. To analyse the atmospheric circulation geopotential data at 850 hPa are also taken from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis datasets. For the years in which extreme summers in terms of high solar irradiation and low precipitation are identified, the previous late winter/spring conditions of solar irradiation and precipitation in Germany and adjacent areas are analysed. Results show that if the El Niño-Southern Oscillation (ENSO) is not very intensely developed, extremely high solar irradiation amounts, together with extremely low precipitation

  7. Multiple extreme environmental conditions of intermittent soda pans in the Carpathian Basin (Central Europe)

    PubMed Central

    Boros, Emil; Katalin, V.-Balogh; Vörös, Lajos; Horváth, Zsófia

    2017-01-01

    Soda lakes and pans represent saline ecosystems with unique chemical composition, occurring on all continents. The purpose of this study was to identify and characterise the main environmental gradients and trophic state that prevail in the soda pans (n=84) of the Carpathian Basin in Central Europe. Underwater light conditions, dissolved organic matter, phosphorus and chlorophyll a were investigated in 84 pans during 2009–2010. Besides, water temperature was measured hourly with an automatic sensor throughout one year in a selected pan. The pans were very shallow (median depth: 15 cm), and their extremely high turbidity (Secchi depth median: 3 cm, min: 0.5 cm) was caused by high concentrations of inorganic suspended solids (median: 0.4 g L–1, max: 16 g L–1), which was the dominant (>50%) contributing factor to the vertical attenuation coefficient in 67 pans (80%). All pans were polyhumic (median DOC: 47 mg L–1), and total phosphorus concentration was also extremely high (median: 2 mg L–1, max: 32 mg L–1). The daily water temperature maximum (44 °C) and fluctuation maximum (28 °C) were extremely high during summertime. The combination of environmental boundaries: shallowness, daily water temperature fluctuation, intermittent hydroperiod, high turbidity, polyhumic organic carbon concentration, high alkalinity and hypertrophy represent a unique extreme aquatic ecosystem. PMID:28572691

  8. Lichens as a Model-System for Symbiotic Organisms under Simulated Extreme Space Conditions

    NASA Astrophysics Data System (ADS)

    de Vera, J.; Horneck, G.; Rettberg, P.; Ott, S.

    As a consequence of the symbiotic state of lichens both the bionts are able to colonize habitats where the separate bionts would not be able to survive. The symbiosis of lichens reflects a high degree of complexity and plasticity. The combination of the different bionts enables these organisms to colonize most extreme habitats worldwide from the Arctic and Alpine zones to the Antarctic. Besides the already well investigated microorganisms lichens are good model -systems to examine adaptation strategies to most extreme environments. Because of the symbiotic nature of the lichens a 3-component -system can be used for investigations: the mycobiont (fungi), the photobiont (algae) and the lichen itself. Our investigations are based on such a system related to simulated extreme conditions. The influence of different doses of UV A, B, C (>200nm) on the vitality of fungal (mycobiont) fruiting bodys and their spores and the germination process has been investigated. The spores are cultivated on a variety of different substrates, especially on a Martian Regolith Simulant JSC - 1-A g a r- Extract for testing the influence of the UV radiation related to the dependency of different soil-substrate-extracts. The influence of vacuum conditions has been investigated. The aim of this research is to test the reaction of a symbiotic organism complex and its respective bionts to highly extreme space conditions looking forward to a possibly survival strategy of lichenized associations in space; probably supporting the theory of Panspermia. For the interpretation of results especially refering to the vitality potential of the photobionts in damaged and healthy lichens the method of modern confocal lasermicroscopy (CLSM) - a novel method in lichenology is presented.

  9. Reduced CO2 fertilization effect in temperate C3 grasslands under more extreme weather conditions

    NASA Astrophysics Data System (ADS)

    Obermeier, W. A.; Lehnert, L. W.; Kammann, C. I.; Müller, C.; Grünhage, L.; Luterbacher, J.; Erbs, M.; Moser, G.; Seibert, R.; Yuan, N.; Bendix, J.

    2017-02-01

    The increase in atmospheric greenhouse gas concentrations from anthropogenic activities is the major driver of recent global climate change. The stimulation of plant photosynthesis due to rising atmospheric carbon dioxide concentrations ([CO2]) is widely assumed to increase the net primary productivity (NPP) of C3 plants--the CO2 fertilization effect (CFE). However, the magnitude and persistence of the CFE under future climates, including more frequent weather extremes, are controversial. Here we use data from 16 years of temperate grassland grown under `free-air carbon dioxide enrichment’ conditions to show that the CFE on above-ground biomass is strongest under local average environmental conditions. The observed CFE was reduced or disappeared under wetter, drier and/or hotter conditions when the forcing variable exceeded its intermediate regime. This is in contrast to predictions of an increased CO2 fertilization effect under drier and warmer conditions. Such extreme weather conditions are projected to occur more intensely and frequently under future climate scenarios. Consequently, current biogeochemical models might overestimate the future NPP sink capacity of temperate C3 grasslands and hence underestimate future atmospheric [CO2] increase.

  10. Reduced CO2 fertilization effect in temperate C3 grasslands under more extreme weather conditions

    NASA Astrophysics Data System (ADS)

    Obermeier, W. A.; Lehnert, L. W.; Kammann, C. I.; Müller, C.; Grünhage, L.; Luterbacher, J.; Erbs, M.; Moser, G.; Seibert, R.; Yuan, N.; Bendix, J.

    2016-12-01

    The increase in atmospheric greenhouse gas concentrations from anthropogenic activities is the major driver of recent global climate change. The stimulation of plant photosynthesis due to rising atmospheric carbon dioxide concentrations ([CO2]) is widely assumed to increase the net primary productivity (NPP) of C3 plants--the CO2 fertilization effect (CFE). However, the magnitude and persistence of the CFE under future climates, including more frequent weather extremes, are controversial. Here we use data from 16 years of temperate grassland grown under `free-air carbon dioxide enrichment’ conditions to show that the CFE on above-ground biomass is strongest under local average environmental conditions. The observed CFE was reduced or disappeared under wetter, drier and/or hotter conditions when the forcing variable exceeded its intermediate regime. This is in contrast to predictions of an increased CO2 fertilization effect under drier and warmer conditions. Such extreme weather conditions are projected to occur more intensely and frequently under future climate scenarios. Consequently, current biogeochemical models might overestimate the future NPP sink capacity of temperate C3 grasslands and hence underestimate future atmospheric [CO2] increase.

  11. Regionalisation of climate change factors of peak flow quantiles in Lower Saxony

    NASA Astrophysics Data System (ADS)

    Plötner, Stefan; Haberlandt, Uwe; Petry, Uwe

    2017-04-01

    In order to project changes in flood flows climate change factors can be used. These are estimated by hydrological modelling for future and historical conditions, deriving flood peak distributions each and calculating ratios of the obtained peak flow quantiles. The changes factors can then be applied to observed or modelled flood quantiles to estimate possible future design flows. To predict in ungauged basins a regionalisation of the change factors is necessary. This utilisation of change factors is assumed to be more robust regarding the bias in climate models, regarding scale problems when using daily time steps for modelling and allows the application to any reference data set. For 178 meso-scale catchments in Lower Saxony the conceptual rainfall-runoff-model HBV-IWW is set up on a lumped and daily basis. The models are calibrated using a multi-criteria optimisation approach for the time period 1951-2013. 8 RCP 8.5 and 6 SRES A1B scenario datasets are used to derive the climate change factors of peak flow quantiles for the far future 2071-2100 against the reference time period 1971-2000. Three different methods: Multiple Linear Regression, Ordinary Kriging and Kriging with External Drift are investigated to regionalise the climate change factors. Due to the uncertainty of future climate an ensemble of simulations is used. This contribution answers questions regarding the best interpolation method, the optimal combination of climate scenarios and the assessment of uncertainty in the prediction.

  12. Estimating risks to aquatic life using quantile regression

    USGS Publications Warehouse

    Schmidt, Travis S.; Clements, William H.; Cade, Brian S.

    2012-01-01

    One of the primary goals of biological assessment is to assess whether contaminants or other stressors limit the ecological potential of running waters. It is important to interpret responses to contaminants relative to other environmental factors, but necessity or convenience limit quantification of all factors that influence ecological potential. In these situations, the concept of limiting factors is useful for data interpretation. We used quantile regression to measure risks to aquatic life exposed to metals by including all regression quantiles (τ  =  0.05–0.95, by increments of 0.05), not just the upper limit of density (e.g., 90th quantile). We measured population densities (individuals/0.1 m2) of 2 mayflies (Rhithrogena spp., Drunella spp.) and a caddisfly (Arctopsyche grandis), aqueous metal mixtures (Cd, Cu, Zn), and other limiting factors (basin area, site elevation, discharge, temperature) at 125 streams in Colorado. We used a model selection procedure to test which factor was most limiting to density. Arctopsyche grandis was limited by other factors, whereas metals limited most quantiles of density for the 2 mayflies. Metals reduced mayfly densities most at sites where other factors were not limiting. Where other factors were limiting, low mayfly densities were observed despite metal concentrations. Metals affected mayfly densities most at quantiles above the mean and not just at the upper limit of density. Risk models developed from quantile regression showed that mayfly densities observed at background metal concentrations are improbable when metal mixtures are at US Environmental Protection Agency criterion continuous concentrations. We conclude that metals limit potential density, not realized average density. The most obvious effects on mayfly populations were at upper quantiles and not mean density. Therefore, we suggest that policy developed from mean-based measures of effects may not be as useful as policy based on the concept of

  13. Interventions for the prevention and management of neck/upper extremity musculoskeletal conditions: a systematic review

    PubMed Central

    Boocock, M G; McNair, P J; Larmer, P J; Armstrong, B; Collier, J; Simmonds, M; Garrett, N

    2007-01-01

    Considered from medical, social or economic perspectives, the cost of musculoskeletal injuries experienced in the workplace is substantial, and there is a need to identify the most efficacious interventions for their effective prevention, management and rehabilitation. Previous reviews have highlighted the limited number of studies that focus on upper extremity intervention programmes. The aim of this study was to evaluate the findings of primary, secondary and/or tertiary intervention studies for neck/upper extremity conditions undertaken between 1999 and 2004 and to compare these results with those of previous reviews. Relevant studies were retrieved through the use of a systematic approach to literature searching and evaluated using a standardised tool. Evidence was then classified according to a “pattern of evidence” approach. Studies were categorised into subgroups depending on the type of intervention: mechanical exposure interventions; production systems/organisational culture interventions and modifier interventions. 31 intervention studies met the inclusion criteria. The findings provided evidence to support the use of some mechanical and modifier interventions as approaches for preventing and managing neck/upper extremity musculoskeletal conditions and fibromyalgia. Evidence to support the benefits of production systems/organisational culture interventions was found to be lacking. This review identified no single‐dimensional or multi‐dimensional strategy for intervention that was considered effective across occupational settings. There is limited information to support the establishment of evidence‐based guidelines applicable to a number of industrial sectors. PMID:16973739

  14. Interventions for the prevention and management of neck/upper extremity musculoskeletal conditions: a systematic review.

    PubMed

    Boocock, M G; McNair, P J; Larmer, P J; Armstrong, B; Collier, J; Simmonds, M; Garrett, N

    2007-05-01

    Considered from medical, social or economic perspectives, the cost of musculoskeletal injuries experienced in the workplace is substantial, and there is a need to identify the most efficacious interventions for their effective prevention, management and rehabilitation. Previous reviews have highlighted the limited number of studies that focus on upper extremity intervention programmes. The aim of this study was to evaluate the findings of primary, secondary and/or tertiary intervention studies for neck/upper extremity conditions undertaken between 1999 and 2004 and to compare these results with those of previous reviews. Relevant studies were retrieved through the use of a systematic approach to literature searching and evaluated using a standardised tool. Evidence was then classified according to a "pattern of evidence" approach. Studies were categorised into subgroups depending on the type of intervention: mechanical exposure interventions; production systems/organisational culture interventions and modifier interventions. 31 intervention studies met the inclusion criteria. The findings provided evidence to support the use of some mechanical and modifier interventions as approaches for preventing and managing neck/upper extremity musculoskeletal conditions and fibromyalgia. Evidence to support the benefits of production systems/organisational culture interventions was found to be lacking. This review identified no single-dimensional or multi-dimensional strategy for intervention that was considered effective across occupational settings. There is limited information to support the establishment of evidence-based guidelines applicable to a number of industrial sectors.

  15. Variable Selection for Nonparametric Quantile Regression via Smoothing Spline AN OVA

    PubMed Central

    Lin, Chen-Yen; Bondell, Howard; Zhang, Hao Helen; Zou, Hui

    2014-01-01

    Quantile regression provides a more thorough view of the effect of covariates on a response. Nonparametric quantile regression has become a viable alternative to avoid restrictive parametric assumption. The problem of variable selection for quantile regression is challenging, since important variables can influence various quantiles in different ways. We tackle the problem via regularization in the context of smoothing spline ANOVA models. The proposed sparse nonparametric quantile regression (SNQR) can identify important variables and provide flexible estimates for quantiles. Our numerical study suggests the promising performance of the new procedure in variable selection and function estimation. Supplementary materials for this article are available online. PMID:24554792

  16. Calcification of a common Caribbean coral under extreme conditions of natural acidification

    NASA Astrophysics Data System (ADS)

    Crook, E. D.; Cohen, A. L.; Hernandez-Terrones, L.; Rebolledo-Vieyra, M.; Paytan, A.

    2011-12-01

    Coral reef ecosystems are currently threatened by anthropogenic loading of CO2 to the atmosphere and global surface oceans. Model predictions and laboratory experiments indicate that as the pH of the oceans drops, the ability of calcifying corals to build their carbonate skeletons will be significantly reduced. Here, we investigate coral calcification under extreme conditions of natural ocean acidification in a reef lagoon at Puerto Morelos, Mexico. The lagoon experiences highly localized drops in pH (6.8 to 7.6) and its close proximity to organisms living under ambient conditions provides a unique opportunity to study the impacts of ocean acidification on calcification. 3D CT scanning and image analysis were used to precisely measure the linear extension, density, and calcification of 14 Porites astreoides cores. Importantly, corals are still able to calcify under extreme (undersaturated) conditions, and normal rates of linear extension are maintained. However, the total amount of calcium carbonate produced by the corals declines with decreasing aragonite saturation state. Thus, while linear extension does not significantly vary, skeletal density declines by approximately 34%, resulting in an approximate calcification decrease of 38%. As a result, skeletons accreted under acidic conditions are fragile and more prone to breakage and boring by sponges and bivalve mollusks. We address the importance of these implications for the integrity of coral colonies and reefs as a whole.

  17. Extreme spring conditions in the Arctic delay spring phenology of long-distance migratory songbirds.

    PubMed

    Boelman, Natalie T; Krause, Jesse S; Sweet, Shannan K; Chmura, Helen E; Perez, Jonathan H; Gough, Laura; Wingfield, John C

    2017-08-04

    Arctic regions are warming rapidly, with extreme weather events increasing in frequency, duration, and intensity just as in other regions. Many studies have focused on how shifting seasonality in environmental conditions affects vegetation phenology, while far fewer have examined how the breeding phenology of arctic fauna responds. We studied two species of long-distance migratory songbirds, Lapland longspurs, Calcarius lapponicus, and white-crowned sparrows, Zonotrichia leucophrys gambelii, across five consecutive breeding seasons in northern Alaskan tundra. We aimed to understand how spring environmental conditions affected breeding cycle phenology, including the timing of arrival on breeding grounds, territory establishment, and clutch initiation. Spring temperatures, precipitation, and snow-free dates differed significantly among years, with 2013 characterized by unusually late snow cover. In response, we found a significant delay in breeding-cycle phenology for both study species in 2013 relative to other study years: the first bird observed was delayed by 6-10 days, with mean arrival by 3-6 days, territory establishment by 6-13 days, and clutch initiation by 4-10 days. Further, snow cover, temperature, and precipitation during the territory establishment period were important predictors of clutch initiation dates for both species. These findings suggest that Arctic-breeding passerine communities may have the flexibility required to adjust breeding phenology in response to the increasingly extreme and unpredictable environmental conditions-although future generations may encounter conditions that exceed their current range of phenological flexibility.

  18. Local Composite Quantile Regression Smoothing for Harris Recurrent Markov Processes

    PubMed Central

    Li, Degui; Li, Runze

    2016-01-01

    In this paper, we study the local polynomial composite quantile regression (CQR) smoothing method for the nonlinear and nonparametric models under the Harris recurrent Markov chain framework. The local polynomial CQR regression method is a robust alternative to the widely-used local polynomial method, and has been well studied in stationary time series. In this paper, we relax the stationarity restriction on the model, and allow that the regressors are generated by a general Harris recurrent Markov process which includes both the stationary (positive recurrent) and nonstationary (null recurrent) cases. Under some mild conditions, we establish the asymptotic theory for the proposed local polynomial CQR estimator of the mean regression function, and show that the convergence rate for the estimator in nonstationary case is slower than that in stationary case. Furthermore, a weighted type local polynomial CQR estimator is provided to improve the estimation efficiency, and a data-driven bandwidth selection is introduced to choose the optimal bandwidth involved in the nonparametric estimators. Finally, we give some numerical studies to examine the finite sample performance of the developed methodology and theory. PMID:27667894

  19. Quantile uncertainty and value-at-risk model risk.

    PubMed

    Alexander, Carol; Sarabia, José María

    2012-08-01

    This article develops a methodology for quantifying model risk in quantile risk estimates. The application of quantile estimates to risk assessment has become common practice in many disciplines, including hydrology, climate change, statistical process control, insurance and actuarial science, and the uncertainty surrounding these estimates has long been recognized. Our work is particularly important in finance, where quantile estimates (called Value-at-Risk) have been the cornerstone of banking risk management since the mid 1980s. A recent amendment to the Basel II Accord recommends additional market risk capital to cover all sources of "model risk" in the estimation of these quantiles. We provide a novel and elegant framework whereby quantile estimates are adjusted for model risk, relative to a benchmark which represents the state of knowledge of the authority that is responsible for model risk. A simulation experiment in which the degree of model risk is controlled illustrates how to quantify Value-at-Risk model risk and compute the required regulatory capital add-on for banks. An empirical example based on real data shows how the methodology can be put into practice, using only two time series (daily Value-at-Risk and daily profit and loss) from a large bank. We conclude with a discussion of potential applications to nonfinancial risks. © 2012 Society for Risk Analysis.

  20. Isolation and Characterization of Bacteria Capable of Tolerating the Extreme Conditions of Clean Room Environments▿

    PubMed Central

    La Duc, Myron T.; Dekas, Anne; Osman, Shariff; Moissl, Christine; Newcombe, David; Venkateswaran, Kasthuri

    2007-01-01

    In assessing the bacterial populations present in spacecraft assembly, spacecraft test, and launch preparation facilities, extremophilic bacteria (requiring severe conditions for growth) and extremotolerant bacteria (tolerant to extreme conditions) were isolated. Several cultivation approaches were employed to select for and identify bacteria that not only survive the nutrient-limiting conditions of clean room environments but can also withstand even more inhospitable environmental stresses. Due to their proximity to spacefaring objects, these bacteria pose a considerable risk for forward contamination of extraterrestrial sites. Samples collected from four geographically distinct National Aeronautics and Space Administration clean rooms were challenged with UV-C irradiation, 5% hydrogen peroxide, heat shock, pH extremes (pH 3.0 and 11.0), temperature extremes (4°C to 65°C), and hypersalinity (25% NaCl) prior to and/or during cultivation as a means of selecting for extremotolerant bacteria. Culture-independent approaches were employed to measure viable microbial (ATP-based) and total bacterial (quantitative PCR-based) burdens. Intracellular ATP concentrations suggested a viable microbial presence ranging from below detection limits to 106 cells/m2. However, only 0.1 to 55% of these viable cells were able to grow on defined culture medium. Isolated members of the Bacillaceae family were more physiologically diverse than those reported in previous studies, including thermophiles (Geobacillus), obligate anaerobes (Paenibacillus), and halotolerant, alkalophilic species (Oceanobacillus and Exiguobacterium). Non-spore-forming microbes (α- and β-proteobacteria and actinobacteria) exhibiting tolerance to the selected stresses were also encountered. The multiassay cultivation approach employed herein enhances the current understanding of the physiological diversity of bacteria housed in these clean rooms and leads us to ponder the origin and means of translocation of

  1. Seasonal Forecasts of Extreme Conditions for Wildland Fire Management in Alaska using NMME

    NASA Astrophysics Data System (ADS)

    Bhatt, U. S.; Bieniek, P.; Thoman, R.; York, A.; Ziel, R.

    2016-12-01

    The summer of 2015 was the second largest Alaska fire season since 1950 where approximately the land area of Massachusetts burned. The record fire year of 2004 resulted in 6.5 million acres burned and was costly from property loss (> 35M) and emergency personnel (> 17M). In addition to requiring significant resources, wildfire smoke impacts air quality in Alaska and downstream into North America. Fires in Alaska result from lightning strikes coupled with persistent (extreme) dry warm conditions in remote areas with limited fire management and the seasonal climate/weather determine the extent of the fire season in Alaska. Fire managers rely on weather/climate outlooks for allocating staff and resources from days to a season in advance. Though currently few tested products are available at the seasonal scale. Probabilistic forecasts of the expected seasonal climate/weather would aid tremendously in the planning process. Advanced knowledge of both lightning and fuel conditions would assist managers in planning resource allocation for the upcoming season. For fuel conditions, the Canadian Forest Fire Weather Index System (CFFWIS) has been used since 1992 because it better suits the Alaska fire regime than the standard US National Fire Danger Rating System (NFDRS). This CFFWIS is based on early afternoon values of 2-m air temperature, relative humidity, and 10-m winds and daily total precipitation. Extremes of these indices and the variables are used to calculate these indices will be defined in reference to fire weather for the boreal forest. The CFFWIS will be applied and evaluated for the NMME hindcasts. This study will evaluate the quality of the forecasts comparing the hindcast NMME CFFWIS to acres burned in Alaska. Spatial synoptic patterns in the NMME related to fire weather extremes will be constructed using self-organized maps and probabilities of occurrence will be evaluated against acres burned.

  2. Isolation and characterization of bacteria capable of tolerating the extreme conditions of clean room environments.

    PubMed

    La Duc, Myron T; Dekas, Anne; Osman, Shariff; Moissl, Christine; Newcombe, David; Venkateswaran, Kasthuri

    2007-04-01

    In assessing the bacterial populations present in spacecraft assembly, spacecraft test, and launch preparation facilities, extremophilic bacteria (requiring severe conditions for growth) and extremotolerant bacteria (tolerant to extreme conditions) were isolated. Several cultivation approaches were employed to select for and identify bacteria that not only survive the nutrient-limiting conditions of clean room environments but can also withstand even more inhospitable environmental stresses. Due to their proximity to spacefaring objects, these bacteria pose a considerable risk for forward contamination of extraterrestrial sites. Samples collected from four geographically distinct National Aeronautics and Space Administration clean rooms were challenged with UV-C irradiation, 5% hydrogen peroxide, heat shock, pH extremes (pH 3.0 and 11.0), temperature extremes (4 degrees C to 65 degrees C), and hypersalinity (25% NaCl) prior to and/or during cultivation as a means of selecting for extremotolerant bacteria. Culture-independent approaches were employed to measure viable microbial (ATP-based) and total bacterial (quantitative PCR-based) burdens. Intracellular ATP concentrations suggested a viable microbial presence ranging from below detection limits to 10(6) cells/m(2). However, only 0.1 to 55% of these viable cells were able to grow on defined culture medium. Isolated members of the Bacillaceae family were more physiologically diverse than those reported in previous studies, including thermophiles (Geobacillus), obligate anaerobes (Paenibacillus), and halotolerant, alkalophilic species (Oceanobacillus and Exiguobacterium). Non-spore-forming microbes (alpha- and beta-proteobacteria and actinobacteria) exhibiting tolerance to the selected stresses were also encountered. The multiassay cultivation approach employed herein enhances the current understanding of the physiological diversity of bacteria housed in these clean rooms and leads us to ponder the origin and means

  3. Synchrotron Studies Under Extreme Conditions: Tackling the Multi-Phase with the Multi-Anvil

    NASA Astrophysics Data System (ADS)

    Whitaker, M. L.; Chen, H.; Vaughan, M. T.; Weidner, D. J.

    2012-12-01

    Understanding the properties and behaviors of materials and multi-phase aggregates under conditions of high pressure and temperature are vital to unraveling the mysteries that lie beneath the surface of the planet. Advances in in situ experimental techniques utilizing synchrotron radiation at these extreme conditions have helped to provide answers to many fundamental questions that were previously unattainable. In particular, the Multi-Anvil apparatus has proven to be an invaluable tool for studying the morphological characteristics and physical properties of materials under extreme conditions as a function of pressure, temperature, stress, strain, and time. Moreover, the science is still continuing to evolve, and we have begun to step outside the realm of the static into the study of dynamic processes and their real-time responses to changes in the aforementioned variables, and even to the frequency and rate of these changes. This presentation will discuss the evolution and present state of the art in synchrotron-based multi-anvil techniques at the COMPRES-funded X17MAC Facility at the National Synchrotron Light Source, of which Professor R.C. Liebermann has been an integral player during his scientific career, and particularly during his tenure as President of COMPRES.

  4. Adhesiveness of a new testosterone-in-adhesive matrix patch after extreme conditions.

    PubMed

    Raynaud, Jean-Pierre; Augès, Marie; Liorzou, Laurent; Turlier, Virginie; Lauze, Christophe

    2009-06-22

    The objective of the study was to evaluate the adhesiveness of a new thin, transparent and comfortable testosterone-in-adhesive matrix patch, Testopatch, after extreme conditions. The study was a single-centre, open-label with randomization of sites (upper arms, lower back, thighs) and sides (left, right) of two 45 cm(2) patches, in 24 healthy subjects. Patches were symmetrically applied on one of the three sites. One patch was removed after 2.0 h, under resting conditions and the other patch was removed at 3.5 h, after extreme conditions (physical exercise, sauna, whirl bath). Adhesiveness was assessed of the area stuck and the measure of the forces necessary for patch removal using a Peel Patch Tester. Local safety was assessed at 2.0 and 3.5 h. After physical exercise and after sauna, patch adhesiveness was excellent (95%) when applied on the thigh and very good (90%) on the upper arm. Forces of patch removal were significantly lower at 3.5 h than 2.0 h, and at the lower back compared to the other application sites. There were no adverse effects. Slight erythema was observed that was considered to be clinically insignificant. Testopatch was safe and displayed adhesiveness, compatible with physical activities.

  5. Normal and Extreme Wind Conditions for Power at Coastal Locations in China

    PubMed Central

    Gao, Meng; Ning, Jicai; Wu, Xiaoqing

    2015-01-01

    In this paper, the normal and extreme wind conditions for power at 12 coastal locations along China’s coastline were investigated. For this purpose, the daily meteorological data measured at the standard 10-m height above ground for periods of 40–62 years are statistically analyzed. The East Asian Monsoon that affects almost China’s entire coastal region is considered as the leading factor determining wind energy resources. For most stations, the mean wind speed is higher in winter and lower in summer. Meanwhile, the wind direction analysis indicates that the prevalent winds in summer are southerly, while those in winter are northerly. The air densities at different coastal locations differ significantly, resulting in the difference in wind power density. The Weibull and lognormal distributions are applied to fit the yearly wind speeds. The lognormal distribution performs better than the Weibull distribution at 8 coastal stations according to two judgement criteria, the Kolmogorov–Smirnov test and absolute error (AE). Regarding the annual maximum extreme wind speed, the generalized extreme value (GEV) distribution performs better than the commonly-used Gumbel distribution. At these southeastern coastal locations, strong winds usually occur in typhoon season. These 4 coastal provinces, that is, Guangdong, Fujian, Hainan, and Zhejiang, which have abundant wind resources, are also prone to typhoon disasters. PMID:26313256

  6. Normal and Extreme Wind Conditions for Power at Coastal Locations in China.

    PubMed

    Gao, Meng; Ning, Jicai; Wu, Xiaoqing

    2015-01-01

    In this paper, the normal and extreme wind conditions for power at 12 coastal locations along China's coastline were investigated. For this purpose, the daily meteorological data measured at the standard 10-m height above ground for periods of 40-62 years are statistically analyzed. The East Asian Monsoon that affects almost China's entire coastal region is considered as the leading factor determining wind energy resources. For most stations, the mean wind speed is higher in winter and lower in summer. Meanwhile, the wind direction analysis indicates that the prevalent winds in summer are southerly, while those in winter are northerly. The air densities at different coastal locations differ significantly, resulting in the difference in wind power density. The Weibull and lognormal distributions are applied to fit the yearly wind speeds. The lognormal distribution performs better than the Weibull distribution at 8 coastal stations according to two judgement criteria, the Kolmogorov-Smirnov test and absolute error (AE). Regarding the annual maximum extreme wind speed, the generalized extreme value (GEV) distribution performs better than the commonly-used Gumbel distribution. At these southeastern coastal locations, strong winds usually occur in typhoon season. These 4 coastal provinces, that is, Guangdong, Fujian, Hainan, and Zhejiang, which have abundant wind resources, are also prone to typhoon disasters.

  7. Dehydrin stress proteins in Pinus sylvestris L. needles under conditions of extreme climate of Yakutia.

    PubMed

    Tatarinova, T D; Perk, A A; Bubyakina, V V; Vasilieva, I V; Ponomarev, A G; Maximov, T C

    2017-03-01

    This is the first study to investigate stress proteins dehydrins with the use of specific antibodies in the Scots pine (Pinus sylvestris L.) needles and their changes in the annual cycle under extreme climate of Yakutia. No pronounced polymorphism of major dehydrins (14-15 and 66 kDa) has been found during the winter dormancy period of P. sylvestris. A clear correlation between the seasonal variations in dehydrins and changes in the water content in needles was revealed. Consistently high levels of dehydrins was retained throughout the period of low negative temperatures. It is assumed that dehydrins can participate in the formation of P. sylvestris L. resistance to the permafrost conditions.

  8. The phase-contrast imaging instrument at the matter in extreme conditions endstation at LCLS

    DOE PAGES

    Nagler, Bob; Schropp, Andreas; Galtier, Eric C.; ...

    2016-10-07

    Here, we describe the phase-contrast imaging instrument at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source. The instrument can image phenomena with a spatial resolution of a few hundreds of nanometers and at the same time reveal the atomic structure through X-ray diffraction, with a temporal resolution better than 100 fs. It was specifically designed for studies relevant to high-energy-density science and can monitor, e.g., shock fronts, phase transitions, or void collapses. This versatile instrument was commissioned last year and is now available to the MEC user community.

  9. The phase-contrast imaging instrument at the matter in extreme conditions endstation at LCLS

    SciTech Connect

    Nagler, Bob; Schropp, Andreas; Galtier, Eric C.; Arnold, Brice; Brown, Shaughnessy B.; Fry, Alan; Gleason, Arianna; Granados, Eduardo; Hashim, Akel; Hastings, Jerome B.; Samberg, Dirk; Seiboth, Frank; Tavella, Franz; Xing, Zhou; Lee, Hae Ja; Schroer, Christian G.

    2016-10-07

    Here, we describe the phase-contrast imaging instrument at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source. The instrument can image phenomena with a spatial resolution of a few hundreds of nanometers and at the same time reveal the atomic structure through X-ray diffraction, with a temporal resolution better than 100 fs. It was specifically designed for studies relevant to high-energy-density science and can monitor, e.g., shock fronts, phase transitions, or void collapses. This versatile instrument was commissioned last year and is now available to the MEC user community.

  10. [Morphofunctional characteristics of the placenta of women living in extreme conditions of the Aral cost line].

    PubMed

    Ataniiazova, O A; Ezhova, L S; Kondrikov, N I

    1994-01-01

    Morphologic examination of the placenta from 41 puerperants living near the Aral sea revealed an increase of its mass and changes in other parameters. The detected pathologic processes: hemodynamic disorders and dystrophic changes--are not specific and contribute to the development of placental insufficiency. The majority (85.6%) of newborns were born in asphyxia. Morphofunctional features of the placentas of multiparous women and the status of their children permit regarding this population as the best adapted to pregnancy and delivery of viable children under the said extreme conditions.

  11. Quantile Regression in the Study of Developmental Sciences

    PubMed Central

    Petscher, Yaacov; Logan, Jessica A. R.

    2014-01-01

    Linear regression analysis is one of the most common techniques applied in developmental research, but only allows for an estimate of the average relations between the predictor(s) and the outcome. This study describes quantile regression, which provides estimates of the relations between the predictor(s) and outcome, but across multiple points of the outcome’s distribution. Using data from the High School and Beyond and U.S. Sustained Effects Study databases, quantile regression is demonstrated and contrasted with linear regression when considering models with: (a) one continuous predictor, (b) one dichotomous predictor, (c) a continuous and a dichotomous predictor, and (d) a longitudinal application. Results from each example exhibited the differential inferences which may be drawn using linear or quantile regression. PMID:24329596

  12. Dietary diversity, socioeconomic status and maternal body mass index (BMI): quantile regression analysis of nationally representative data from Ghana, Namibia and Sao Tome and Principe

    PubMed Central

    Amugsi, Dickson A; Dimbuene, Zacharie T; Bakibinga, Pauline; Kimani-Murage, Elizabeth W; Haregu, Tilahun Nigatu; Mberu, Blessing

    2016-01-01

    Objectives To (a) assess the association between dietary diversity (DD) score, socioeconomic status (SES) and maternal body mass index (BMI), and (b) the variation of the effects of DD and SES at different points of the conditional distribution of the BMI. Methods The study used Demographic and Health Surveys round 5 data sets from Ghana, Namibia and Sao Tome and Principe. The outcome variable for the analysis was maternal BMI. The DD score was computed using 24-hour dietary recall data. Quantile regression (QR) was used to examine the relationship between DD and SES, and maternal BMI, adjusting for other covariates. The QR allows the covariate effects to vary across the entire distribution of maternal BMI. Results Women who consumed an additional unit of DD achieved an increase of 0.245 in BMI for those in the 90th quantile in Ghana. The effect of household wealth increases for individuals across all quantiles of the BMI distribution and in all the 3 countries. A unit change in the household wealth score was associated with an increase of 0.038, 0.052 and 0.065 units increase in BMI for individuals in the 5th quantile in Ghana, Namibia and Sao Tome and Principe, respectively. Also, 0.237, 0.301 and 0.174 units increased for those in the 90th quantile in Ghana, Namibia and Sao Tome and Principe, respectively. Education had a significant positive effect on maternal BMI across all quantiles in Namibia and negative effect at the 5th, 10th and 90th quantiles in Sao Tome and Principe. Conclusions There is heterogeneity in the effects of DD and SES on maternal BMI. Studies focusing on the effects of diet and socioeconomic determinants on maternal BMI should examine patterns of effects at different points of the conditional distribution of the BMI and not just the average effect. PMID:27678544

  13. Censored Quantile Instrumental Variable Estimates of the Price Elasticity of Expenditure on Medical Care.

    PubMed

    Kowalski, Amanda

    2016-01-02

    Efforts to control medical care costs depend critically on how individuals respond to prices. I estimate the price elasticity of expenditure on medical care using a censored quantile instrumental variable (CQIV) estimator. CQIV allows estimates to vary across the conditional expenditure distribution, relaxes traditional censored model assumptions, and addresses endogeneity with an instrumental variable. My instrumental variable strategy uses a family member's injury to induce variation in an individual's own price. Across the conditional deciles of the expenditure distribution, I find elasticities that vary from -0.76 to -1.49, which are an order of magnitude larger than previous estimates.

  14. Censored Quantile Instrumental Variable Estimates of the Price Elasticity of Expenditure on Medical Care

    PubMed Central

    Kowalski, Amanda

    2015-01-01

    Efforts to control medical care costs depend critically on how individuals respond to prices. I estimate the price elasticity of expenditure on medical care using a censored quantile instrumental variable (CQIV) estimator. CQIV allows estimates to vary across the conditional expenditure distribution, relaxes traditional censored model assumptions, and addresses endogeneity with an instrumental variable. My instrumental variable strategy uses a family member’s injury to induce variation in an individual’s own price. Across the conditional deciles of the expenditure distribution, I find elasticities that vary from −0.76 to −1.49, which are an order of magnitude larger than previous estimates. PMID:26977117

  15. Data quantile-quantile plots: quantifying the time evolution of space climatology

    NASA Astrophysics Data System (ADS)

    Tindale, Elizabeth; Chapman, Sandra

    2017-04-01

    The solar wind is inherently variable across a wide range of spatio-temporal scales; embedded in the flow are the signatures of distinct non-linear physical processes from evolving turbulence to the dynamical solar corona. In-situ satellite observations of solar wind magnetic field and velocity are at minute and below time resolution and now extend over several solar cycles. Each solar cycle is unique, and the space climatology challenge is to quantify how solar wind variability changes within, and across, each distinct solar cycle, and how this in turn drives space weather at earth. We will demonstrate a novel statistical method, that of data-data quantile-quantile (DQQ) plots, which quantifies how the underlying statistical distribution of a given observable is changing in time. Importantly this method does not require any assumptions concerning the underlying functional form of the distribution and can identify multi-component behaviour that is changing in time. This can be used to determine when a sub-range of a given observable is undergoing a change in statistical distribution, or where the moments of the distribution only are changing and the functional form of the underlying distribution is not changing in time. The method is quite general; for this application we use data from the WIND satellite to compare the solar wind across the minima and maxima of solar cycles 23 and 24 [1], and how these changes are manifest in parameters that quantify coupling to the earth's magnetosphere. [1] Tindale, E., and S.C. Chapman (2016), Geophys. Res. Lett., 43(11), doi: 10.1002/2016GL068920.

  16. Extreme Sea Conditions in Shallow Water: Estimation based on in-situ measurements

    NASA Astrophysics Data System (ADS)

    Le Crom, Izan; Saulnier, Jean-Baptiste

    2013-04-01

    The design of marine renewable energy devices and components is based, among others, on the assessment of the environmental extreme conditions (winds, currents, waves, and water level) that must be combined together in order to evaluate the maximal loads on a floating/fixed structure, and on the anchoring system over a determined return period. Measuring devices are generally deployed at sea over relatively short durations (a few months to a few years), typically when describing water free surface elevation, and extrapolation methods based on hindcast data (and therefore on wave simulation models) have to be used. How to combine, in a realistic way, the action of the different loads (winds and waves for instance) and which correlation of return periods should be used are highly topical issues. However, the assessment of the extreme condition itself remains a not-fully-solved, crucial, and sensitive task. Above all in shallow water, extreme wave height, Hmax, is the most significant contribution in the dimensioning process of EMR devices. As a case study, existing methodologies for deep water have been applied to SEMREV, the French marine energy test site. The interest of this study, especially at this location, goes beyond the simple application to SEMREV's WEC and floating wind turbines deployment as it could also be extended to the Banc de Guérande offshore wind farm that are planned close by. More generally to pipes and communication cables as it is a redundant problematic. The paper will first present the existing measurements (wave and wind on site), the prediction chain that has been developed via wave models, the extrapolation methods applied to hindcast data, and will try to formulate recommendations for improving this assessment in shallow water.

  17. Regional flood quantile estimation for a Weibull Model

    NASA Astrophysics Data System (ADS)

    Boes, Duane C.; Heo, Jun-Haeng; Salas, Jose D.

    1989-05-01

    Estimation of annual flood quantiles at a given site, based on a regional Weibull model with independence in space and time, is considered. A common shape parameter over sites, motivated by an index flood assumption, was assumed. An exact simple formula for the Cramer-Rao lower bound for the variance of unbiased estimators of the quantile is obtained, and the gain of regional flood frequency analysis over single-site analysis can be quantified via this formula. The estimation techniques of the method of moments, the method of probability-weighted moments, and the method of maximum likelihood are compared.

  18. Comparison of different hydrological similarity measures to estimate flow quantiles

    NASA Astrophysics Data System (ADS)

    Rianna, M.; Ridolfi, E.; Napolitano, F.

    2017-07-01

    This paper aims to evaluate the influence of hydrological similarity measures on the definition of homogeneous regions. To this end, several attribute sets have been analyzed in the context of the Region of Influence (ROI) procedure. Several combinations of geomorphological, climatological, and geographical characteristics are also used to cluster potentially homogeneous regions. To verify the goodness of the resulting pooled sites, homogeneity tests arecarried out. Through a Monte Carlo simulation and a jack-knife procedure, flow quantiles areestimated for the regions effectively resulting as homogeneous. The analysis areperformed in both the so-called gauged and ungauged scenarios to analyze the effect of hydrological measures on flow quantiles estimation.

  19. Spline methods for approximating quantile functions and generating random samples

    NASA Technical Reports Server (NTRS)

    Schiess, J. R.; Matthews, C. G.

    1985-01-01

    Two cubic spline formulations are presented for representing the quantile function (inverse cumulative distribution function) of a random sample of data. Both B-spline and rational spline approximations are compared with analytic representations of the quantile function. It is also shown how these representations can be used to generate random samples for use in simulation studies. Comparisons are made on samples generated from known distributions and a sample of experimental data. The spline representations are more accurate for multimodal and skewed samples and to require much less time to generate samples than the analytic representation.

  20. Formation of molten metal films during metal-on-metal slip under extreme interfacial conditions

    NASA Astrophysics Data System (ADS)

    Liou, Nai-Shang; Okada, Makoto; Prakash, Vikas

    2004-09-01

    The present paper describes results of plate-impact pressure-shear friction experiments conducted to study time-resolved growth of molten metal films during dry metal-on-metal slip under extreme interfacial conditions. By employing tribo-pairs comprising hard tool-steel against relatively low melt-point metals such as 7075-T6 aluminum alloys, interfacial friction stress ranging from 100 to 400 MPa and slip speeds of approximately 100 m/ s have been generated. These relatively high levels of friction stress combined with high slip-speeds generate conditions conducive for interfacial temperatures to approach the melting point of the lower melt point metal (Al alloy) comprising the tribo-pair. A Lagrangian finite element code is developed to understand the evolution of the thermo-mechanical fields and their relationship to the observed slip response. The code accounts for dynamic effects, heat conduction, contact with friction, and full thermo-mechanical coupling. At temperatures below the melting point the material is described as an isotropic thermally softening elastic-viscoplastic solid. For material elements with temperatures in excess of the melt point a purely Newtonian fluid constitutive model is employed. The results of the hybrid experimental-computational study provides new insights into the thermoelastic-plastic interactions during high speed metal-on-metal slip under extreme interfacial conditions. During the early part of frictional slip the coefficient of kinetic friction is observed to decrease with increasing slip velocity. During the later part transition in interfacial slip occurs from dry metal-on-metal sliding to the formation of molten Al films at the tribo-pair interface. Under these conditions the interfacial resistance approaches the shear strength of the molten aluminum alloy under normal pressures of approximately 1- 3 GPa and shear strain rates of ˜10 7 s-1. The results of the study indicate that under these extreme conditions molten

  1. Quantitative evaluation of the mitochondrial proteomes of Drosophila melanogaster adapted to extreme oxygen conditions.

    PubMed

    Yin, Songyue; Xue, Jin; Sun, Haidan; Wen, Bo; Wang, Quanhui; Perkins, Guy; Zhao, Huiwen W; Ellisman, Mark H; Hsiao, Yu-hsin; Yin, Liang; Xie, Yingying; Hou, Guixue; Zi, Jin; Lin, Liang; Haddad, Gabriel G; Zhou, Dan; Liu, Siqi

    2013-01-01

    Mitochondria are the primary organelles that consume oxygen and provide energy for cellular activities. To investigate the mitochondrial mechanisms underlying adaptation to extreme oxygen conditions, we generated Drosophila strains that could survive in low- or high-oxygen environments (LOF or HOF, respectively), examined their mitochondria at the ultrastructural level via transmission electron microscopy, studied the activity of their respiratory chain complexes, and quantitatively analyzed the protein abundance responses of the mitochondrial proteomes using Isobaric tag for relative and absolute quantitation (iTRAQ). A total of 718 proteins were identified with high confidence, and 55 and 75 mitochondrial proteins displayed significant differences in abundance in LOF and HOF, respectively, compared with the control flies. Importantly, these differentially expressed mitochondrial proteins are primarily involved in respiration, calcium regulation, the oxidative response, and mitochondrial protein translation. A correlation analysis of the changes in the levels of the mRNAs corresponding to differentially regulated mitochondrial proteins revealed two sets of proteins with different modes of regulation (transcriptional vs. post-transcriptional) in both LOF and HOF. We believe that these findings will not only enhance our understanding of the mechanisms underlying adaptation to extreme oxygen conditions in Drosophila but also provide a clue in studying human disease induced by altered oxygen tension in tissues and cells.

  2. Pi2 Pulsations During Extremely Quiet Geomagnetic Condition: Van Allen Probe Observations

    NASA Astrophysics Data System (ADS)

    Ghamry, Essam

    2017-06-01

    A ultra low frequency (ULF) wave, Pi2, has been reported to occur during periods of extremely quiet magnetospheric and solar wind conditions. And no statistical study on the Pi2 has been performed during extremely quiet conditions, using satellite observations to the author’s knowledge. Also Pi2 pulsations in the space fluxgate magnetometers near perigee failed to attract scientist’s attention previously. In this paper, Pi2 pulsations detected by the Van Allen probe satellites (VAP-A & VAP-B) were investigated statistically. During the period from October 2012 to December 2014, ninety six Pi2 events were identified using VAP when Kp = 0 while using Kakioka (KAK, L = 1.23) as a reference ground station. Seventy five events had high coherence between VAP-Bz and H components at KAK station. As a result, it was found that 77 % of the events had power spectra between 5 and 12 mHz, which differs from the regular Pi2 band range of from 6.7 to 25 mHz. In addition, it was shown that it is possible to observe Pi2 pulsations from space fluxgate magnetometers near perigee. Twenty two clean Pi2 pulsations were found where L < 4 and four examples of Pi2 oscillations at different L shells are presented in this paper.

  3. Influence of Extreme Storage Conditions on Extra Virgin Olive Oil Parameters: Traceability Study

    PubMed Central

    Escudero, Alfredo; Pacheco, Rafael

    2016-01-01

    This study reflects the effect of extreme storage conditions on several extra virgin olive oil (EVOO) varieties (arbequina, hojiblanca, and picual). The conditions were simulated in the laboratory, by means of heating treatments in stove at different temperatures (40 and 60°C) and times (two and three weeks). The aim is the evaluation of the deterioration of the quality parameters and minority components, which are responsible for the nutritional and therapeutic properties (fatty acids, polyphenols, pigments, and tocopherols), and organoleptic qualities. The quality criteria and limits used in this work are according to International Olive Council. The results contribute to the control of the traSceability for the commercialization of the EVOO. PMID:28042493

  4. Fitness to work of astronauts in conditions of action of the extreme emotional factors

    NASA Astrophysics Data System (ADS)

    Prisniakova, L. M.

    2004-01-01

    The theoretical model for the quantitative determination of influence of a level of emotional exertion on the success of human activity is presented. The learning curves of fixed words in the groups with a different level of the emotional exertion are analyzed. The obtained magnitudes of time constant T depending on a type of the emotional exertion are a quantitative measure of the emotional exertion. Time constants could also be of use for a prediction of the characteristic of fitness to work of an astronaut in conditions of extreme factors. The inverse of the sign of influencing on efficiency of activity of the man is detected. The paper offers a mathematical model of the relation between successful activity and motivations or the emotional exertion (Yerkes-Dodson law). Proposed models can serve by the theoretical basis of the quantitative characteristics of an estimation of activity of astronauts in conditions of the emotional factors at a phase of their selection.

  5. Extreme Wave-Induced Oscillation in Paradip Port Under the Resonance Conditions

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Gulshan

    2017-08-01

    A mathematical model is constructed to analyze the long wave-induced oscillation in Paradip Port, Odisha, India under the resonance conditions to avert any extreme wave hazards. Boundary element method (BEM) with corner contribution is utilized to solve the Helmholtz equation under the partial reflection boundary conditions. Furthermore, convergence analysis is also performed for the boundary element scheme with uniform and non-uniform discretization of the boundary. The numerical scheme is also validated with analytic approximation and existing studies based on harbor resonance. Then, the amplification factor is estimated at six key record stations in the Paradip Port with multidirectional incident waves and resonance modes are also estimated at the boundary of the port. Ocean surface wave field is predicted in the interior of Paradip Port for the different directional incident wave at various resonance modes. Moreover, the safe locations in the port have been identified for loading and unloading of moored ship with different resonance modes and directional incident waves.

  6. Sulfidogenesis under extremely haloalkaline conditions in soda lakes of Kulunda Steppe (Altai, Russia).

    PubMed

    Sorokin, Dimitry Y; Rusanov, Igor I; Pimenov, Nikolai V; Tourova, Tatjana P; Abbas, Ben; Muyzer, Gerard

    2010-08-01

    Sulfidogenic activity (SA) in anoxic sediments of several soda lakes with variable salinity in south Kulunda Steppe (Altai, Russia) has been investigated. The study included in situ measurements of sulfate reduction rates and laboratory experiments with sediment slurries in which sulfate, thiosulfate or elemental sulfur were used as electron acceptors. Despite the extreme conditions (high salt concentrations and high pH), the SA values were relatively high (ranging from 0.02 to 1.20 micromol HS(-) cm(-3) h(-1)), and only hampered under salt-saturated conditions. The highest SA was observed with elemental sulfur, followed by thiosulfate, while the lowest SA was determined in the presence of sulfate. Of all the electron donors tested, the addition of formate resulted in the highest SA with all three sulfur electron acceptors. Surprisingly, hydrogen as an electron donor had very little effect. Acetate was utilized as an electron donor only under sulfur-reducing conditions. Indigenous populations of sulfidogens in soda lake sediments showed an obligately alkaliphilic pH response of SA, showing a pattern that corresponded well to the in situ pH conditions. Sulfate reduction was much more susceptible to salt inhibition than thiosulfate and sulfur reduction. Microbiological investigations indicated that sulfate-reducing bacteria belonging to the orders Desulfovibrionales and Desulfobacterales could very likely be responsible for the SA with sulfate and thiosulfate as electron acceptors at moderate salt concentrations. Sulfur reduction at moderate salinity was carried out by a specialized group of haloalkaliphilic sulfur-reducing bacteria that utilize volatile fatty acids. In saturated soda brine, extremely natronophilic representatives of the order Halanaerobiales were responsible for the sulfur-dependent respiration.

  7. Space-Borne Ku-Band Radar Observations of Extreme Surface Water Conditions

    NASA Astrophysics Data System (ADS)

    Nghiem, S. V.

    2005-12-01

    Acceleration of the global water cycle may lead to an exacerbation of hydrologic extremes. A multitude of extreme events has occurred in the last decade over the world including droughts, floods, record snow accumulation, and minimal ice cover with severe environmental and socioeconomic impacts. This paper presents an overview of the capabilities of space-borne Ku-band radar to measure extreme conditions of surface water including liquid and solid phases on land, ice, and oceans. Ku-band backscatter data acquired globally by the QuikSCAT satellite scatterometer are used to obtain the results. Hurricane Katrina in 2005 is the deadliest and costliest in U.S. with far-reaching impacts. Radar results of surface water over southern and eastern U.S. reveal the extreme extent of precipitation water deposited on land surface compared to the case of Hurricane Ivan in 2004. Radar monitoring of surface water pattern in California shows the extreme prolonged duration of precipitation-induced water in the 2005 wettest winter season over a century causing widespread flooding and landslide. For drought monitoring, radar maps of precipitation frequency over the U.S. Midwest in summer seasons indicate a sharp change to a severe drought in 2003 from the most frequent rains in 2000. Kenya experienced the worst drought in 45 years affecting more than 3 million people in 2000 when the radar data over Nairobi identified the collapse of the long rain season. Since then, satellite radar time-series up to July 2005 shows the consistency of the annual bimodal precipitation seasons suggesting an improvement in the local drought conditions. In cold land regions, backscatter data map seasonal snowmelt processes showing large variabilities in time and in space over the northern hemisphere. Satellite Ku-band radar measurements of snow accumulation on the Greenland ice sheet identify and map the record snow accumulation in the first quarter of 2005, verified with field observations and

  8. Concrete Condition Assessment Using Impact-Echo Method and Extreme Learning Machines

    PubMed Central

    Zhang, Jing-Kui; Yan, Weizhong; Cui, De-Mi

    2016-01-01

    The impact-echo (IE) method is a popular non-destructive testing (NDT) technique widely used for measuring the thickness of plate-like structures and for detecting certain defects inside concrete elements or structures. However, the IE method is not effective for full condition assessment (i.e., defect detection, defect diagnosis, defect sizing and location), because the simple frequency spectrum analysis involved in the existing IE method is not sufficient to capture the IE signal patterns associated with different conditions. In this paper, we attempt to enhance the IE technique and enable it for full condition assessment of concrete elements by introducing advanced machine learning techniques for performing comprehensive analysis and pattern recognition of IE signals. Specifically, we use wavelet decomposition for extracting signatures or features out of the raw IE signals and apply extreme learning machine, one of the recently developed machine learning techniques, as classification models for full condition assessment. To validate the capabilities of the proposed method, we build a number of specimens with various types, sizes, and locations of defects and perform IE testing on these specimens in a lab environment. Based on analysis of the collected IE signals using the proposed machine learning based IE method, we demonstrate that the proposed method is effective in performing full condition assessment of concrete elements or structures. PMID:27023563

  9. Three responses of wetland conditions to climatic extremes in the Prairie Pothole Region

    USGS Publications Warehouse

    Cressey, Ryann L.; Austin, Jane; Stafford, Joshua D.

    2016-01-01

    Wetlands in central North Dakota were revisited after 50 years to assess changes following extreme drought and a prolonged wet period. We compared data collected during 1961–1966 to current (2013–2014) wetland conditions. We revisited 80 wetlands in 2013 and 2014 across three study areas and measured wetland area, ponded-water depth, and specific conductance. Wetlands at the three study areas responded to prolonged wet conditions in one of three ways. Wetlands at Crystal Springs became larger, and had deeper ponds of lower specific conductance in 2013–14 compared to the 1960s. Wetlands at Cottonwood were larger with deeper ponds of slightly higher specific conductance in 2013–2014. Wetlands at Mt. Moriah had only subtle changes in size, pond depth, and specific conductance between periods. Prolonged wet conditions led to merging of most wetlands (defined as the outer edge of wet-meadow vegetation) at Crystal Springs and a few wetlands at Cottonwood. Low topographic relief at Crystal Springs and Cottonwood contributed to storage of excess water in wetlands with associated responses to prolonged wet conditions. In contrast, higher topographic relief and natural outlets into two intermittent streams at Mt. Moriah resulted in wetlands being less impacted by prolonged wet conditions.

  10. Concrete Condition Assessment Using Impact-Echo Method and Extreme Learning Machines.

    PubMed

    Zhang, Jing-Kui; Yan, Weizhong; Cui, De-Mi

    2016-03-26

    The impact-echo (IE) method is a popular non-destructive testing (NDT) technique widely used for measuring the thickness of plate-like structures and for detecting certain defects inside concrete elements or structures. However, the IE method is not effective for full condition assessment (i.e., defect detection, defect diagnosis, defect sizing and location), because the simple frequency spectrum analysis involved in the existing IE method is not sufficient to capture the IE signal patterns associated with different conditions. In this paper, we attempt to enhance the IE technique and enable it for full condition assessment of concrete elements by introducing advanced machine learning techniques for performing comprehensive analysis and pattern recognition of IE signals. Specifically, we use wavelet decomposition for extracting signatures or features out of the raw IE signals and apply extreme learning machine, one of the recently developed machine learning techniques, as classification models for full condition assessment. To validate the capabilities of the proposed method, we build a number of specimens with various types, sizes, and locations of defects and perform IE testing on these specimens in a lab environment. Based on analysis of the collected IE signals using the proposed machine learning based IE method, we demonstrate that the proposed method is effective in performing full condition assessment of concrete elements or structures.

  11. Spatiotemporal patterns and trends of Indian monsoonal rainfall extremes

    PubMed Central

    Malik, Nishant; Bookhagen, Bodo; Mucha, Peter J.

    2016-01-01

    In this study, we provide a comprehensive analysis of trends in the extremes during the Indian summer monsoon (ISM) months (June to September) at different temporal and spatial scales. Our goal is to identify and quantify spatiotemporal patterns and trends that have emerged during the recent decades and may be associated with changing climatic conditions. Our analysis primarily relies on quantile regression that avoids making any subjective choices on spatial, temporal, or intensity pattern of extreme rainfall events. Our analysis divides the Indian monsoon region into climatic compartments that show different and partly opposing trends. These include strong trends towards intensified droughts in Northwest India, parts of Peninsular India, and Myanmar; in contrast, parts of Pakistan, Northwest Himalaya, and Central India show increased extreme daily rain intensity leading to higher flood vulnerability. Our analysis helps explain previously contradicting results of trends in average ISM rainfall. PMID:27909349

  12. Spatiotemporal patterns and trends of Indian monsoonal rainfall extremes

    NASA Astrophysics Data System (ADS)

    Malik, Nishant; Bookhagen, Bodo; Mucha, Peter J.

    2016-02-01

    In this study, we provide a comprehensive analysis of trends in the extremes during the Indian summer monsoon (ISM) months (June to September) at different temporal and spatial scales. Our goal is to identify and quantify spatiotemporal patterns and trends that have emerged during the recent decades and may be associated with changing climatic conditions. Our analysis primarily relies on quantile regression that avoids making any subjective choices on spatial, temporal, or intensity pattern of extreme rainfall events. Our analysis divides the Indian monsoon region into climatic compartments that show different and partly opposing trends. These include strong trends toward intensified droughts in Northwest India, parts of Peninsular India, and Myanmar; in contrast, parts of Pakistan, Northwest Himalaya, and Central India show increased extreme daily rain intensity leading to higher flood vulnerability. Our analysis helps explain previously contradicting results of trends in average ISM rainfall.

  13. Logistic quantile regression provides improved estimates for bounded avian counts: A case study of California Spotted Owl fledgling production

    USGS Publications Warehouse

    Cade, Brian S.; Noon, Barry R.; Scherer, Rick D.; Keane, John J.

    2017-01-01

    Counts of avian fledglings, nestlings, or clutch size that are bounded below by zero and above by some small integer form a discrete random variable distribution that is not approximated well by conventional parametric count distributions such as the Poisson or negative binomial. We developed a logistic quantile regression model to provide estimates of the empirical conditional distribution of a bounded discrete random variable. The logistic quantile regression model requires that counts are randomly jittered to a continuous random variable, logit transformed to bound them between specified lower and upper values, then estimated in conventional linear quantile regression, repeating the 3 steps and averaging estimates. Back-transformation to the original discrete scale relies on the fact that quantiles are equivariant to monotonic transformations. We demonstrate this statistical procedure by modeling 20 years of California Spotted Owl fledgling production (0−3 per territory) on the Lassen National Forest, California, USA, as related to climate, demographic, and landscape habitat characteristics at territories. Spotted Owl fledgling counts increased nonlinearly with decreasing precipitation in the early nesting period, in the winter prior to nesting, and in the prior growing season; with increasing minimum temperatures in the early nesting period; with adult compared to subadult parents; when there was no fledgling production in the prior year; and when percentage of the landscape surrounding nesting sites (202 ha) with trees ≥25 m height increased. Changes in production were primarily driven by changes in the proportion of territories with 2 or 3 fledglings. Average variances of the discrete cumulative distributions of the estimated fledgling counts indicated that temporal changes in climate and parent age class explained 18% of the annual variance in owl fledgling production, which was 34% of the total variance. Prior fledgling production explained as much of

  14. Influenza transmission during extreme indoor conditions in a low-resource tropical setting

    NASA Astrophysics Data System (ADS)

    Tamerius, James; Ojeda, Sergio; Uejio, Christopher K.; Shaman, Jeffrey; Lopez, Brenda; Sanchez, Nery; Gordon, Aubree

    2017-04-01

    Influenza transmission occurs throughout the planet across wide-ranging environmental conditions. However, our understanding of the environmental factors mediating transmission is evaluated using outdoor environmental measurements, which may not be representative of the indoor conditions where influenza is transmitted. In this study, we examined the relationship between indoor environment and influenza transmission in a low-resource tropical population. We used a case-based ascertainment design to enroll 34 households with a suspected influenza case and then monitored households for influenza, while recording indoor temperature and humidity data in each household. We show that the indoor environment is not commensurate with outdoor conditions and that the relationship between indoor and outdoor conditions varies significantly across homes. We also show evidence of influenza transmission in extreme indoor environments. Specifically, our data suggests that indoor environments averaged 29 °C, 18 g/kg specific humidity, and 68 % relative humidity across 15 transmission events observed. These indoor settings also exhibited significant temporal variability with temperatures as high as 39 °C and specific and relative humidity increasing to 22 g/kg and 85 %, respectively, during some transmission events. However, we were unable to detect differences in the transmission efficiency by indoor temperature or humidity conditions. Overall, these results indicate that laboratory studies investigating influenza transmission and virus survival should increase the range of environmental conditions that they assess and that observational studies investigating the relationship between environment and influenza activity should use caution using outdoor environmental measurements since they can be imprecise estimates of the conditions that mediate transmission indoors.

  15. Influenza transmission during extreme indoor conditions in a low-resource tropical setting

    NASA Astrophysics Data System (ADS)

    Tamerius, James; Ojeda, Sergio; Uejio, Christopher K.; Shaman, Jeffrey; Lopez, Brenda; Sanchez, Nery; Gordon, Aubree

    2016-08-01

    Influenza transmission occurs throughout the planet across wide-ranging environmental conditions. However, our understanding of the environmental factors mediating transmission is evaluated using outdoor environmental measurements, which may not be representative of the indoor conditions where influenza is transmitted. In this study, we examined the relationship between indoor environment and influenza transmission in a low-resource tropical population. We used a case-based ascertainment design to enroll 34 households with a suspected influenza case and then monitored households for influenza, while recording indoor temperature and humidity data in each household. We show that the indoor environment is not commensurate with outdoor conditions and that the relationship between indoor and outdoor conditions varies significantly across homes. We also show evidence of influenza transmission in extreme indoor environments. Specifically, our data suggests that indoor environments averaged 29 °C, 18 g/kg specific humidity, and 68 % relative humidity across 15 transmission events observed. These indoor settings also exhibited significant temporal variability with temperatures as high as 39 °C and specific and relative humidity increasing to 22 g/kg and 85 %, respectively, during some transmission events. However, we were unable to detect differences in the transmission efficiency by indoor temperature or humidity conditions. Overall, these results indicate that laboratory studies investigating influenza transmission and virus survival should increase the range of environmental conditions that they assess and that observational studies investigating the relationship between environment and influenza activity should use caution using outdoor environmental measurements since they can be imprecise estimates of the conditions that mediate transmission indoors.

  16. Identification of extreme motor phenotypes in Huntington's disease.

    PubMed

    Braisch, Ulrike; Hay, Birgit; Muche, Rainer; Rothenbacher, Dietrich; Landwehrmeyer, G Bernhard; Long, Jeffrey D; Orth, Michael

    2017-04-01

    The manifestation of motor signs in Huntington's disease (HD) has a well-known inverse relationship with HTT CAG repeat length, but the prediction is far from perfect. The probability of finding disease modifiers is enhanced in individuals with extreme HD phenotypes. We aimed to identify extreme HD motor phenotypes conditional on CAG and age, such as patients with very early or very late onset of motor manifestation. Retrospective data were available from 1,218 healthy controls and 9,743 HD participants with CAG repeats ≥40, and a total of about 30,000 visits. Boundaries (2.5% and 97.5% quantiles) for extreme motor phenotypes (UHDRS total motor score (TMS) and motor age-at-onset) were estimated using quantile regression for longitudinal data. More than 15% of HD participants had an extreme TMS phenotype for at least one visit. In contrast, only about 4% of participants were consistent TMS extremes at two or more visits. Data from healthy controls revealed an upper cut-off of 13 for the TMS representing the extreme of motor ratings for a normal aging population. In HD, boundaries of motor age-at-onset based on diagnostic confidence or derived from the TMS data cut-off in controls were similar. In summary, a UHDRS TMS of more than 13 in an individual carrying the HD mutation indicates a high likelihood of motor manifestations of HD irrespective of CAG repeat length or age. The identification of motor phenotype extremes can be useful in the search for disease modifiers, for example, genetic or environmental such as medication. © 2016 Wiley Periodicals, Inc.

  17. Analysis of variance, normal quantile-quantile correlation and effective expression support of pooled expression ratio of reference genes for defining expression stability.

    PubMed

    Priyadarshi, Himanshu; Das, Rekha; Kumar, Shivendra; Kishore, Pankaj; Kumar, Sujit

    2017-01-01

    Identification of a reference gene unaffected by the experimental conditions is obligatory for accurate measurement of gene expression through relative quantification. Most existing methods directly analyze variability in crossing point (Cp) values of reference genes and fail to account for template-independent factors that affect Cp values in their estimates. We describe the use of three simple statistical methods namely analysis of variance (ANOVA), normal quantile-quantile correlation (NQQC) and effective expression support (EES), on pooled expression ratios of reference genes in a panel to overcome this issue. The pooling of expression ratios across the genes in the panel nullify the sample specific effects uniformly affecting all genes that are falsely reflected as instability. Our methods also offer the flexibility to include sample specific PCR efficiencies in estimations, when available, for improved accuracy. Additionally, we describe a correction factor from the ANOVA method to correct the relative fold change of a target gene if no truly stable reference gene could be found in the analyzed panel. The analysis is described on a synthetic data set to simplify the explanation of the statistical treatment of data.

  18. The fate of carbon dioxide in water-rich fluids under extreme conditions

    PubMed Central

    Pan, Ding; Galli, Giulia

    2016-01-01

    Investigating the fate of dissolved carbon dioxide under extreme conditions is critical to understanding the deep carbon cycle in Earth, a process that ultimately influences global climate change. We used first-principles molecular dynamics simulations to study carbonates and carbon dioxide dissolved in water at pressures (P) and temperatures (T) approximating the conditions of Earth’s upper mantle. Contrary to popular geochemical models assuming that molecular CO2(aq) is the major carbon species present in water under deep Earth conditions, we found that at 11 GPa and 1000 K, carbon exists almost entirely in the forms of solvated carbonate (CO32−) and bicarbonate (HCO3−) ions and that even carbonic acid [H2CO3(aq)] is more abundant than CO2(aq). Furthermore, our simulations revealed that ion pairing between Na+ and CO32−/HCO3− is greatly affected by P-T conditions, decreasing with increasing pressure at 800 to 1000 K. Our results suggest that in Earth’s upper mantle, water-rich geofluids transport a majority of carbon in the form of rapidly interconverting CO32− and HCO3− ions, not solvated CO2(aq) molecules. PMID:27757424

  19. The fate of carbon dioxide in water-rich fluids under extreme conditions.

    PubMed

    Pan, Ding; Galli, Giulia

    2016-10-01

    Investigating the fate of dissolved carbon dioxide under extreme conditions is critical to understanding the deep carbon cycle in Earth, a process that ultimately influences global climate change. We used first-principles molecular dynamics simulations to study carbonates and carbon dioxide dissolved in water at pressures (P) and temperatures (T) approximating the conditions of Earth's upper mantle. Contrary to popular geochemical models assuming that molecular CO2(aq) is the major carbon species present in water under deep Earth conditions, we found that at 11 GPa and 1000 K, carbon exists almost entirely in the forms of solvated carbonate ([Formula: see text]) and bicarbonate ([Formula: see text]) ions and that even carbonic acid [H2CO3(aq)] is more abundant than CO2(aq). Furthermore, our simulations revealed that ion pairing between Na(+) and [Formula: see text]/[Formula: see text] is greatly affected by P-T conditions, decreasing with increasing pressure at 800 to 1000 K. Our results suggest that in Earth's upper mantle, water-rich geofluids transport a majority of carbon in the form of rapidly interconverting [Formula: see text] and [Formula: see text] ions, not solvated CO2(aq) molecules.

  20. Impacts of extreme hydro-meteorological conditions on ecosystem functioning and productivity patterns across Australia

    NASA Astrophysics Data System (ADS)

    Huete, Alfredo; Ma, Xuanlong; Xie, Zunyi; Restrepo-Coupe, Natalia; Ponce-Campos, Guillermo

    2016-04-01

    As Earth's climate continues to change, the frequency and intensity of warm droughts, extreme precipitation patterns, and heat waves will alter in potentially different ways, ecosystem structure and functioning with major impacts on carbon and water balance, and food security. The extreme hydro-meteorological conditions that are presently impacting Australia approach those anticipated with future climate change and thus provide unique opportunities to study ecological sensitivity and functional responses and cross-biome productivity changes using contemporary, in-situ and satellite observational datasets. Here, we combined satellite vegetation index products from MODIS and AVHRR, total water storage (TWS) from the GRACE twin satellites, precipitation data and in-situ tower flux measurements to characterise ecosystem sensitivity, and analyse climate change impacts on ecosystem productivity and resilience. Recent advances in eddy covariance tower flux measurements and spatially contiguous remote sensing data provide innovative and promising capabilities to extend ecosystem functioning and productivity studies from local to regional and continental scales. In general, Australia exhibited ecosystem-level shifts in water demands with water availability across wet and dry years, and over all biomes analysed (arid grasslands to humid forests). In the drier years, higher ecosystem water use efficiencies (WUEe) enabled plants to maintain higher levels of productivity than would otherwise be expected for the lower amounts of rainfall and available water. Further, there were unique, functional class-specific coping strategies to drought and water availability. With prolonged warm drought conditions, biomes became increasingly water-limited and WUEe continued to increase until reaching a 'dry edge' threshold, a cross biome maximum WUEe, that cannot be sustained with further reductions in water availability and could potentially break down ecosystem resilience and induce

  1. The National Ignition Facility: an experimental platform for studying behavior of matter under extreme conditions

    NASA Astrophysics Data System (ADS)

    Moses, Edward

    2011-11-01

    The National Ignition Facility (NIF), a 192-beam Nd-glass laser facility capable of producing 1.8 MJ and 500 TW of ultraviolet light, is now operational at Lawrence Livermore National Laboratory (LLNL). As the world's largest and most energetic laser system, NIF serves as the national center for the U.S. Department of Energy (DOE) and National Nuclear Security Administration to achieve thermonuclear burn in the laboratory and to explore the behavior of matter at extreme temperatures and energy densities. By concentrating the energy from all of its 192 extremely energetic laser beams into a mm3-sized target, NIF can reach the conditions required to initiate fusion reactions. NIF can also provide access to extreme scientific environments: temperatures about 100 million K, densities of 1,000 g/cm3, and pressures 100 billion times atmospheric pressure. These conditions have never been created before in a laboratory and exist naturally only in interiors of the planetary and stellar environments as well as in nuclear weapons. Since August 2009, the NIF team has been conducting experiments in support of the National Ignition Campaign (NIC)—a partnership among LLNL, Los Alamos National Laboratory, General Atomics, the University of Rochester, Sandia National Laboratories, as well as a number of universities and international collaborators. The results from these initial experiments show promise for the relatively near-term achievement of ignition. Capsule implosion experiments at energies up to 1.2 MJ have demonstrated laser energetics, radiation temperatures, and symmetry control that scale to ignition conditions. Of particular importance is the demonstration of peak hohlraum temperatures near 300 eV with overall backscatter less than 10%. Cryogenic target capability and additional diagnostics are being installed in preparation for layered target deuterium-tritium implosions to be conducted later in 2010. Important national security and basic science experiments have

  2. The Proteome of a Healthy Human during Physical Activity under Extreme Conditions

    PubMed Central

    Larina, I. M.; Ivanisenko, V. A.; Nikolaev, E. N.; Grigorev, A. I.

    2014-01-01

    The review examines the new approaches in modern systems biology, in terms of their use for a deeper understanding of the physiological adaptation of a healthy human in extreme environments. Human physiology under extreme conditions of life, or environmental physiology, and systems biology are natural partners. The similarities and differences between the object and methods in systems biology, the OMICs (proteomics, transcriptomics, metabolomics) disciplines, and other related sciences have been studied. The latest data on environmental human physiology obtained using systems biology methods are discussed. The independent achievements of systems biology in studying the adaptation of a healthy human to physical activity, including human presence at high altitude, to the effects of hypoxia and oxidative stress have been noted. A reasonable conclusion is drawn that the application of the methods and approaches used in systems biology to study the molecular pattern of the adaptive mechanisms that develop in the human body during space flight can provide valuable fundamental knowledge and fill the picture of human metabolic pathways. PMID:25349715

  3. Assessing the Land-Ocean Interaction under Extreme Climate Change Condition - a Modeling Approach

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Wang, T.; Leung, R.; Balaguru, K.; Hibbard, K. A.

    2011-12-01

    Many modeling applications, at global and regional scales, have demonstrated that numerical models are useful tools to quantify the uncertainty and the interactions between natural physical and biogeochemical processes and human activities in coastal regions. A regional integrated assessment modeling framework to investigate the interactions of agriculture and land use, coastal ecological issues, energy supply and effects of climate changes is under development by Pacific Northwest National Laboratory (PNNL), with specific application to the Gulf of Mexico. The Gulf is vulnerable to the direct impacts of climate changes, such as sea level rise, hurricane-induced storm surge and extreme floods due to high precipitation and river run-off. This presentation will focus on the coastal modeling aspect of this integrated modeling approach. An unstructured-grid finite volume coastal ocean model, which has the capability of simulating coastal circulation, wave and storm surges, sediment transport and biogeochemical processes, is applied to simulate hurricane storm surges and extreme flood events in the coastal region of Gulf of Mexico. Specifically, storm surge along the US Southeast coasts and freshwater plume in the Mississippi Delta were simulated and compared to observations. Numerical sensitivity studies with boundary conditions and forcing indicated the urgent need of a real observation network as well as the importance of accurate model predictions at regional scales to drive the model at smaller scales. The implication of natural pressures, such as storm surge and flooding to biogeochemical processes and marine ecosystem will be discussed.

  4. Diamonds on Diamond: structural studies at extreme conditions on the Diamond Light Source.

    PubMed

    McMahon, M I

    2015-03-06

    Extreme conditions (EC) research investigates how the structures and physical and chemical properties of materials change when subjected to extremes of pressure and temperature. Pressures in excess of one million times atmospheric pressure can be achieved using a diamond anvil cell, and, in combination with high-energy, micro-focused radiation from a third-generation synchrotron such as Diamond, detailed structural information can be obtained using either powder or single-crystal diffraction techniques. Here, I summarize some of the research drivers behind international EC research, and then briefly describe the techniques by which high-quality diffraction data are obtained. I then highlight the breadth of EC research possible on Diamond by summarizing four examples from work conducted on the I15 and I19 beamlines, including a study which resulted in the first research paper from Diamond. Finally, I look to the future, and speculate as to the type of EC research might be conducted at Diamond over the next 10 years.

  5. Quantile Regression in the Study of Developmental Sciences

    ERIC Educational Resources Information Center

    Petscher, Yaacov; Logan, Jessica A. R.

    2014-01-01

    Linear regression analysis is one of the most common techniques applied in developmental research, but only allows for an estimate of the average relations between the predictor(s) and the outcome. This study describes quantile regression, which provides estimates of the relations between the predictor(s) and outcome, but across multiple points of…

  6. Mathematical Investigation of Bode's Law and Quantilization of Gravity

    NASA Astrophysics Data System (ADS)

    Lu, K. U.

    1995-03-01

    A non-static General Relativistic mathematical solution for the gravitational field around a star is obtained. From this mathematical solution, the orbits of the planets around the Sun are calculated and compared with Bode's law and the mean distances of the orbits, the origin of the Moon is deduced, and a theory for quantilization of gravity is concluded.

  7. Quantile Regression in the Study of Developmental Sciences

    ERIC Educational Resources Information Center

    Petscher, Yaacov; Logan, Jessica A. R.

    2014-01-01

    Linear regression analysis is one of the most common techniques applied in developmental research, but only allows for an estimate of the average relations between the predictor(s) and the outcome. This study describes quantile regression, which provides estimates of the relations between the predictor(s) and outcome, but across multiple points of…

  8. The Microbial Sulfur Cycle at Extremely Haloalkaline Conditions of Soda Lakes

    PubMed Central

    Sorokin, Dimitry Y.; Kuenen, J. Gijs; Muyzer, Gerard

    2011-01-01

    Soda lakes represent a unique ecosystem with extremely high pH (up to 11) and salinity (up to saturation) due to the presence of high concentrations of sodium carbonate in brines. Despite these double extreme conditions, most of the lakes are highly productive and contain a fully functional microbial system. The microbial sulfur cycle is among the most active in soda lakes. One of the explanations for that is high-energy efficiency of dissimilatory conversions of inorganic sulfur compounds, both oxidative and reductive, sufficient to cope with costly life at double extreme conditions. The oxidative part of the sulfur cycle is driven by chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacteria (SOB), which are unique for soda lakes. The haloalkaliphilic SOB are present in the surface sediment layer of various soda lakes at high numbers of up to 106 viable cells/cm3. The culturable forms are so far represented by four novel genera within the Gammaproteobacteria, including the genera Thioalkalivibrio, Thioalkalimicrobium, Thioalkalispira, and Thioalkalibacter. The latter two were only found occasionally and each includes a single species, while the former two are widely distributed in various soda lakes over the world. The genus Thioalkalivibrio is the most physiologically diverse and covers the whole spectrum of salt/pH conditions present in soda lakes. Most importantly, the dominant subgroup of this genus is able to grow in saturated soda brines containing 4 M total Na+ – a so far unique property for any known aerobic chemolithoautotroph. Furthermore, some species can use thiocyanate as a sole energy source and three out of nine species can grow anaerobically with nitrogen oxides as electron acceptor. The reductive part of the sulfur cycle is active in the anoxic layers of the sediments of soda lakes. The in situ measurements of sulfate reduction rates and laboratory experiments with sediment slurries using sulfate, thiosulfate, or elemental sulfur as

  9. The microbial sulfur cycle at extremely haloalkaline conditions of soda lakes.

    PubMed

    Sorokin, Dimitry Y; Kuenen, J Gijs; Muyzer, Gerard

    2011-01-01

    Soda lakes represent a unique ecosystem with extremely high pH (up to 11) and salinity (up to saturation) due to the presence of high concentrations of sodium carbonate in brines. Despite these double extreme conditions, most of the lakes are highly productive and contain a fully functional microbial system. The microbial sulfur cycle is among the most active in soda lakes. One of the explanations for that is high-energy efficiency of dissimilatory conversions of inorganic sulfur compounds, both oxidative and reductive, sufficient to cope with costly life at double extreme conditions. The oxidative part of the sulfur cycle is driven by chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacteria (SOB), which are unique for soda lakes. The haloalkaliphilic SOB are present in the surface sediment layer of various soda lakes at high numbers of up to 10(6) viable cells/cm(3). The culturable forms are so far represented by four novel genera within the Gammaproteobacteria, including the genera Thioalkalivibrio, Thioalkalimicrobium, Thioalkalispira, and Thioalkalibacter. The latter two were only found occasionally and each includes a single species, while the former two are widely distributed in various soda lakes over the world. The genus Thioalkalivibrio is the most physiologically diverse and covers the whole spectrum of salt/pH conditions present in soda lakes. Most importantly, the dominant subgroup of this genus is able to grow in saturated soda brines containing 4 M total Na(+) - a so far unique property for any known aerobic chemolithoautotroph. Furthermore, some species can use thiocyanate as a sole energy source and three out of nine species can grow anaerobically with nitrogen oxides as electron acceptor. The reductive part of the sulfur cycle is active in the anoxic layers of the sediments of soda lakes. The in situ measurements of sulfate reduction rates and laboratory experiments with sediment slurries using sulfate, thiosulfate, or elemental sulfur as

  10. Extreme weather conditions reduce the CO2 fertilization effect in temperate C3 grasslands

    NASA Astrophysics Data System (ADS)

    Obermeier, Wolfgang; Lehnert, Lukas; Kammann, Claudia; Müller, Christoph; Grünhage, Ludger; Luterbacher, Jürg; Erbs, Martin; Yuan, Naiming; Bendix, Jörg

    2016-04-01

    The increase in atmospheric greenhouse gas concentrations from anthropogenic activities is the major driver of global climate change. The rising atmospheric carbon dioxide (CO2) concentrations may stimulate plant photosynthesis and, thus, cause a net sink effect in the global carbon cycle. As a consequence of an enhanced photosynthesis, an increase in the net primary productivity (NPP) of C3 plants (termed CO2 fertilization) is widely assumed. This process is associated with a reduced stomatal conductance of leaves as the carbon demand of photosynthesis is met earlier. This causes a higher water-use efficiency and, hence, may reduce water stress in plants exposed to elevated CO2 concentrations ([eCO2]). However, the magnitude and persistence of the CO2 fertilization effect under a future climate including more frequent weather extremes are controversial. To test the CO2 fertilization effect for Central European grasslands, a data set comprising 16 years of biomass samples and environmental variables such as local weather and soil conditions was analysed by means of a novel approach. The data set was recorded on a "Free Air Carbon dioxide Enrichment" (FACE) experimental site which allows to quantify the CO2 fertilization effect under naturally occurring climate variations. The results indicate that the CO2 fertilization effect on the aboveground biomass is strongest under local average environmental conditions. Such intermediate regimes were defined by the mean +/- 1 standard deviation of the long-term average in the respective variable three months before harvest. The observed CO2 fertilization effect was reduced or vanished under drier, wetter and hotter conditions when the respective variable exceeded the bounds of the intermediate regimes. Comparable conditions, characterized by a higher frequency of more extreme weather conditions, are predicted for the future by climate projections. Consequently, biogeochemical models may overestimate the future NPP sink

  11. Sudden pore pressure rise and rapid landslide initiation induced under extreme rainfall conditions - a case study

    NASA Astrophysics Data System (ADS)

    Fukuoka, Hiroshi; Wang, Fawu; Wang, Gonghui

    2010-05-01

    Since July 19 to 26, 2009, western Japan had a severe rainstorms and caused floods and landslides. Most of the landslides are debris slide - debris flows. Most devastated case took place in Hofu city, Japan. On July 21, extremely intense rainstorm caused numerous debris flows and mud flows in the hillslopes Some of the debris flows destroyed residential houses and home for elderly people, and finally killed 14 residents. Debris flow distribution map was prepared soon based on airphoto interpretation. Japanese Meteorological Agency runs nation-wide ground-based rain gauge network as well as radar rain gauges, which provide hourly to 10 minutes precipitation distribution real-time with spatial resolution of about 5 km. Distribution of daily (cumulative) precipitation of July 21 shows (1) The cumulative precipitation from 6 am -- 12 am of the day was evaluated that their return period could be 200 - 600 years statistically. In 2009, another extraordinary rainfall, of which intensity was evaluated as less than 100 years more more, caused floods in another city claiming many residents lives on the way to evacuation area. Those frequent extraordinary extreme rainfall is not concluded as the consequence of global warming nor climate change, however, those frequency of extreme rainfall events affecting societies are obviously increasing in Japan, too. As for the Hofu city case, it was proved that debris flows took place in the high precipitation area and covered by covered by weathered granite sands and silts which is called "masa". This sands has been proved susceptible against landslides under extreme rainfall conditions. However, the transition from slide - debris flow process is not well revealed, except authors past experiment on the similar masa samples in June 1999 Hiroshima debris flow case. Authors have embedded pore pressure control system for the undrained ring shear apparatus. Strongly weathered sandy soils were sampled just on the smooth and flat granitic

  12. Towards a better understanding of the structure of nano-minerals at ambient and extreme conditions

    SciTech Connect

    Parise, John B.; Ehm, Lars; Michel, F. Marc; Antao, Sytle; Chupas, Peter J.; Lee, Peter L.; Martin, C. David; Shastri, Sarvjit

    2009-01-29

    The high-pressure (HP) behavior of nano-crystalline mackinawite (n-FeS) with particle sizes of 6, 7, and 8 nm has been investigated by high-energy X-ray total scattering and pair distribution function analysis. An irreversible first-order structural phase transition from tetragonal mackinawite to orthorhombic FeS-II was observed at about 3 GPa. The transition is induced by the closure of the van-der-Waals gap in the layered mackinawite structure. A grain size effect on the transition pressure and the compressibility was observed. The n-FcS study is an example of a broad class of nano-crystalline minerals where the total scattering (TS) approach provides significant new information on local-, intermediate- and long-range structure. Under extreme conditions, of pressure in this case, straightforward modifications allow quantitative descriptions of the transformations mechanisms.

  13. Death from Hypothermia during a Training Course under "Extreme Conditions": Related to Two Cases.

    PubMed

    Perich, Pierre; Tuchtan, Lucile; Bartoli, Christophe; Léonetti, Georges; Piercecchi-Marti, Marie-Dominique

    2016-03-01

    Death from hypothermia following exhaustion or from various complicated pathologies is no longer a frequent cause of death among combat troops. During a training course under "extreme conditions" in the French Alps, two young African officers died. Confronted with these two clinically confirmed cases of hypothermia, the unknown anatomopathological and biological specificities associated with death from hypothermia were highlighted. In these typical and clinically confirmed cases of death from subacute exhaustion hypothermia, none of the signs revealed by the autopsy were specific. Although some recent publications have addressed the utility of postmortem biochemical markers when establishing a diagnosis, with no anamnesis, with no knowledge or analysis of the circumstances of death, and without an in situ examination of the body, it appears difficult, if not impossible, to confirm that death was caused by hypothermia.

  14. Sensitivity of mitomycin C and nitrogen mustard crosslinks to extreme alkaline conditions

    SciTech Connect

    Gruenert, D.C.; Cleaver, J.E.

    1984-09-17

    DNA-DNA crosslinks in cells treated with mitomycin C, nitrogen mustard, or decarbamoyl mitomycin C were measured in alkaline isopycnic gradients as a function of pH. Crosslinks from cells treated with mitomycin C and nitrogen mustard, which react with DNA purines, could be detected at pH 12.5 but not at pH 14. No crosslinks from cells treated with decarbamoyl mitomycin C were detected at either pH. Previous studies with cells exposed to psoralen derivatives plus 360 nm light, which produce DNA-DNA crosslinks with pyrimidines, demonstrated stable crosslinks at pH 14. These studies indicate that DNA-DNA crosslinks involving DNA purines are much less stable at high pH than those involving pyrimidines, and that methods involving exposure to extreme alkaline conditions may give inaccurate information for some agents. 25 references, 1 figure.

  15. An unconventional copper protein required for cytochrome c oxidase respiratory function under extreme acidic conditions.

    PubMed

    Castelle, Cindy; Ilbert, Marianne; Infossi, Pascale; Leroy, Gisèle; Giudici-Orticoni, Marie-Thérèse

    2010-07-09

    Very little is known about the processes used by acidophile organisms to preserve stability and function of respiratory pathways. Here, we reveal a potential strategy of these organisms for protecting and keeping functional key enzymes under extreme conditions. Using Acidithiobacillus ferrooxidans, we have identified a protein belonging to a new cupredoxin subfamily, AcoP, for "acidophile CcO partner," which is required for the cytochrome c oxidase (CcO) function. We show that it is a multifunctional copper protein with at least two roles as follows: (i) as a chaperone-like protein involved in the protection of the Cu(A) center of the CcO complex and (ii) as a linker between the periplasmic cytochrome c and the inner membrane cytochrome c oxidase. It could represent an interesting model for investigating the multifunctionality of proteins known to be crucial in pathways of energy metabolism.

  16. Application of an atomic force microscope piezocantilever for dilatometry under extreme conditions

    NASA Astrophysics Data System (ADS)

    Wang, Liran; Schmiedeshoff, George M.; E Graf, David; Park, Ju-Hyun; Murphy, Timothy P.; Tozer, Stanley W.; Palm, Eric; Sarrao, John L.; Cooley, Jason C.

    2017-06-01

    We report on the development of a sensitive dilatometer based upon an atomic force microscope piezocantilever. This dilatometer is designed to measure the elastic properties of bulk materials in extreme conditions, such as temperatures down to 25 mK and magnetic fields up to 16 T. The layered heavy fermion superconductor \\text{CeCoI}{{\\text{n}}5} and its non-magnetic analog \\text{LaRhI}{{\\text{n}}5} are measured to demonstrate their use in detecting phase transitions and quantum oscillations. In addition, using this dilatometer, a simultaneous multi-axis dilation measurement is performed. This compact dilatometer has many advantages, such as its ability to measure very small samples with sub-mm lengths at low temperature and small field dependence, and its ability to rotate, while it works well irrespective of whether it is in a changing liquid or gas environment (i.e. within a flow cryostat or mixing chamber).

  17. Nanocomposite polymeric electrolytes to record electrophysiological brain signals in prolonged, unconventional or extreme conditions.

    PubMed

    Licoccia, Silvia; Luisa Di Vona, M; Romagnoli, Paola; Narici, Livio; Acquaviva, Massimo; Carozzo, Simone; Marco, Stefano Di; Saturno, Moreno; Sannita, Walter G; Traversa, Enrico

    2006-09-01

    Chemically stable nanocomposite iono-conducting polymeric membranes (based on lithium salts and nanocrystalline oxide powders dispersed in a polymethyl methacrylate matrix) performed successfully in the recording of human brain responses to visual stimulation. Impedance was higher than that of conventional electrodes. However, the electrophysiological signals recorded by acid Al(2)O(3) and neutral Al(2)O(3) 5 wt.% and 10 wt.% nanocomposite gel electrolytes were comparable to those obtained with standard electrodes, even without preliminary skin cleaning and in the absence of gel electrolytes allowing better contact with and skin-electrode ionic conductance. The electrochemical and mechanical characteristics of these membranes make them fit for human and animal research, for clinical application (specifically in emergencies, prolonged electrophysiological recordings), or in unconventional or extreme conditions when fluid electrolytes are unsuitable (e.g., biomedical space research).

  18. High-fidelity numerical modeling of the Upper Mississippi River under extreme flood condition

    NASA Astrophysics Data System (ADS)

    Khosronejad, Ali; Le, Trung; DeWall, Petra; Bartelt, Nicole; Woldeamlak, Solomon; Yang, Xiaolei; Sotiropoulos, Fotis

    2016-12-01

    We present data-driven numerical simulations of extreme flooding in a large-scale river coupling coherent-structure resolving hydrodynamics with bed morphodynamics under live-bed conditions. The study area is a ∼ 3.2 km long and ∼ 300 m wide reach of the Upper Mississippi River, near Minneapolis MN, which contains several natural islands and man-made hydraulic structures. We employ the large-eddy simulation (LES) and bed-morphodynamic modules of the Virtual Flow Simulator (VFS-Rivers) model, a recently developed in-house code, to investigate the flow and bed evolution of the river during a 100-year flood event. The coupling of the two modules is carried out via a fluid-structure interaction approach using a nested domain approach to enhance the resolution of bridge scour predictions. We integrate data from airborne Light Detection and Ranging (LiDAR), sub-aqueous sonar apparatus on-board a boat and in-situ laser scanners to construct a digital elevation model of the river bathymetry and surrounding flood plain, including islands and bridge piers. A field campaign under base-flow condition is also carried out to collect mean flow measurements via Acoustic Doppler Current Profiler (ADCP) to validate the hydrodynamic module of the VFS-Rivers model. Our simulation results for the bed evolution of the river under the 100-year flood reveal complex sediment transport dynamics near the bridge piers consisting of both scour and refilling events due to the continuous passage of sand dunes. We find that the scour depth near the bridge piers can reach to a maximum of ∼ 9 m. The data-driven simulation strategy we present in this work exemplifies a practical simulation-based-engineering-approach to investigate the resilience of infrastructures to extreme flood events in intricate field-scale riverine systems.

  19. Atmospheric conditions associated to an extreme rainfall event on Madeira Island (Portugal)

    NASA Astrophysics Data System (ADS)

    Couto, Flavio; Salgado, Rui; João Costa, Maria

    2013-04-01

    Located in the Noth Atlantic Ocean (32°75'N and 17°00'W), the Madeira Island presents favourable conditions for orographic precipitation development, sometimes responsible for high records and floods, such as on 20 February 2010, when the island was affected by the worst flash floods in its recent history, causing more than 40 deaths and huge economic losses. After this disaster, there is a growing interest in understanding the main mechanisms and atmospheric conditions that are relevant to the establishment of extreme rainfall and consequently flash flood occurrences in the island. This study describes the meteorological aspects associated to a case study of high rainfall amounts in Madeira on 25 January 2011. In this case, flash floods and socio-economic damages were not reported, but precipitation above 300 mm in less than 24 hours were observed in Madeira's highlands. The heavy rainfall episode is studied based on rain gauge and satellite observations, as well as numerical simulation with the Mesoscale Non-Hydrostatic Model (MESO-NH). The MESO-NH simulation initialized and forced by ECMWF analysis have been performed with 3 horizontal domains (9, 3 and 1 km resolution), making use of the grid nesting technique. The evolution of the mean sea level pressure field (MSLP) was analyzed from the outer domain outputs, while the other meteorological variables were further explored using the 1 km resolution results. The simulation showed that the orography is crucial in the formation and intensification of the localized heavy rainfall in the island. A remarkable aspect is the fact that this episode occurred in a low-cape environment. Related to the synoptic environment, this event was characterized by a low pressure system centered to the southeastern of the island, in opposition to the results obtained for other extreme events occurred in the past two years, when the high precipitation amounts were due to the effects of the orography on the passage of cold fronts

  20. Why can tiAicrsiYN-based adaptive coatings deliver exceptional performance under extreme frictional conditions?

    PubMed

    Beake, Ben D; Fox-Rabinovich, German S; Losset, Yannick; Yamamoto, Kenji; Agguire, Myriam H; Veldhuis, Stephen C; Endrino, Jose L; Kovalev, Anatoliy I

    2012-01-01

    Adaptive TiAlCrSiYN-based coatings show promise under the extreme tribological conditions of dry ultra-high-speed (500-700 m min-1) machining of hardened tool steels. During high speed machining, protective sapphire and mullite-like tribo-films form on the surface of TiAlCrSiYN-based coatings resulting in beneficial heat-redistribution in the cutting zone. XRD and HRTEM data show that the tribo-films act as a thermal barrier creating a strong thermal gradient. The data are consistent with the temperature decreasing from approximately 1100-1200 degrees C at the outer surface to approximately 600 degrees C at the tribo-film/coating interface. The mechanical properties of the multilayer TiAICrSiYN/TiA1CrN coating were measured by high temperature nanoindentation. It retains relatively high hardness (21 GPa) at 600 degrees C. The nanomechanical properties of the underlying coating layer provide a stable low wear environment for the tribo-films to form and regenerate so it can sustain high temperatures under operation (600 degrees C). This combination of characteristics explains the high wear resistance of the multilayer TiAlCrSiYN/TiAICrN coating under extreme operating conditions. TiAlCrSiYN and TiAlCrN monolayer coatings have a less effective combination of adaptability and mechanical characteristics and therefore lower tool life. The microstructural reasons for different optimum hardness and plasticity between monolayer and multilayer coatings are discussed.

  1. Relative importance of ring and tail currents to Dst under extremely disturbed conditions

    NASA Astrophysics Data System (ADS)

    Kalegaev, V. V.; Makarenkov, E. V.

    2008-02-01

    Relative ring current (RC) and tail current (TC) contributions to Dst were investigated on the basis of the statistical study of 70 magnetic storms of different intensities. Special attention was paid to the extremely disturbed conditions during magnetic storms in October-November 2003. Variations of the magnetic field produced by magnetospheric currents on the Earth's surface were calculated using paraboloid model of the magnetosphere A2000 [Alexeev, I.I., Belenkaya, E.S., Kalegaev, V.V., Feldstein, Y.I., Grafe, A., 1996. Journal of Geophysical Research 101,7737; Alexeev, I.I., Kalegaev, V.V., Belenkaya, E.S., Bobrovnikov, S.Yu., Feldstein, Ya.I., Gromova, L.I., 2001. Journal of Geophysical Research 106, 25683], taking into account the effect of terrestrial induced currents. For each magnetic storm we calculated Dst and contributions produced by large-scale magnetospheric current systems. The relative RC and TC contributions for each event at the storm maximum were examined in relationship to the peak pressure-corrected Dst value. Analysis of Dst sources confirms the conclusions of Kalegaev and Ganushkina [2005. In: Pulkkinen, T., Tsyganenko, N.A., Friedel, R.H.W. (Eds.), Physics and Modeling of the Inner Magnetosphere, AGU Geophysical Monograph 155. AGU, Washington, DC, p. 293] and Kalegaev and Makarenkov [2006. Geomagnetism and Aeronomy 46, 570] about saturation of the TC effect under extremely disturbed conditions. The RC becomes the dominant Dst source during severe magnetic storms, but during moderate storms its contribution to Dst is comparable with TC's contribution. The RC injection amplitude increases with the growth of magnetospheric disturbance level.

  2. Recent Extreme Forest Fire Activity in Western Russia: Fire Danger Conditions, Fire Behavior and Smoke Transport

    NASA Astrophysics Data System (ADS)

    Stocks, B. J.; Fromm, M.; Goldammer, J.; Carr, R.; Sukhinin, A. I.

    2010-12-01

    During the summer of 2010, widespread forest and peatland fires in western Russia burned over hundreds of thousands of hectares, burning over croplands, destroying hundreds of homes, and directly causing the death of more than 50 people. Unprecedented drought conditions, combined with an extended heat wave, resulted in extreme fire danger conditions and explosive fire behavior in a region of Russia not noted for large fires. Several fires exhibited pyroconvection, injecting smoke directly into the upper troposphere and lower stratosphere, while deep-burning fires created major regional smoke problems. This smoke persisted in the heavily-populated areas around Moscow, exposing millions to high levels of ozone and particulate matter, and creating both immediate and longer-term health risks. This presentation will explore the drought conditions leading to the catastrophic fire behavior experienced in western Russia, and analyze fire behavior in terms of fuel consumption, smoke production, fire intensity levels, and pyroconvection. Impacts of regional and long-range smoke transport will also be discussed.

  3. Soda pans of the Pannonian steppe harbor unique bacterial communities adapted to multiple extreme conditions.

    PubMed

    Szabó, Attila; Korponai, Kristóf; Kerepesi, Csaba; Somogyi, Boglárka; Vörös, Lajos; Bartha, Dániel; Márialigeti, Károly; Felföldi, Tamás

    2017-05-01

    Soda pans of the Pannonian steppe are unique environments regarding their physical and chemical characteristics: shallowness, high turbidity, intermittent character, alkaline pH, polyhumic organic carbon concentration, hypertrophic condition, moderately high salinity, sodium and carbonate ion dominance. The pans are highly productive environments with picophytoplankton predominance. Little is known about the planktonic bacterial communities inhabiting these aquatic habitats; therefore, amplicon sequencing and shotgun metagenomics were applied to reveal their composition and functional properties. Results showed a taxonomically complex bacterial community which was distinct from other soda lakes regarding its composition, e.g. the dominance of class Alphaproteobacteria was observed within phylum Proteobacteria. The shotgun metagenomic analysis revealed several functional gene components related to the harsh and at the same time hypertrophic environmental conditions, e.g. proteins involved in stress response, transport and hydrolase systems targeting phytoplankton-derived organic matter. This is the first detailed report on the indigenous planktonic bacterial communities coping with the multiple extreme conditions present in the unique soda pans of the Pannonian steppe.

  4. Diurnal variations of hormonal secretion, alertness and cognition in extreme chronotypes under different lighting conditions

    PubMed Central

    Maierova, L.; Borisuit, A.; Scartezzini, J.-L.; Jaeggi, S. M.; Schmidt, C.; Münch, M.

    2016-01-01

    Circadian rhythms in physiology and behavior are modulated by external factors such as light or temperature. We studied whether self-selected office lighting during the habitual waking period had a different impact on alertness, cognitive performance and hormonal secretion in extreme morning and evening chronotypes (N = 32), whose preferred bed- and wake-up times differed by several hours. The self-selected lighting condition was compared with constant bright light and a control condition in dim light. Saliva samples for hormonal analyses, subjective ratings of alertness, wellbeing, visual comfort and cognitive performance were regularly collected. Between the self-selected and the bright, but not the dim lighting condition, the onset of melatonin secretion in the evening (as marker for circadian phase) was significantly different for both chronotypes. Morning chronotypes reported a faster increase in sleepiness during the day than evening chronotypes, which was associated with higher cortisol secretion. Wellbeing, mood and performance in more difficult cognitive tasks were better in bright and self-selected lighting than in dim light for both chronotypes, whereas visual comfort was best in the self-selected lighting. To conclude, self-selection of lighting at work might positively influence biological and cognitive functions, and allow for inter-individual differences. PMID:27646174

  5. Statistical Analysis of TEC Enhancements during Geomagnetic Disturbances in Extreme Solar Conditions

    NASA Astrophysics Data System (ADS)

    Su, F.

    2014-12-01

    In the past decades, a remarkable set of comprehensive studies and review articles enriched theresearch of the Earth's ionospheric response to geomagnetic disturbances[Prolss, 1995; Buonsanto,1999; Mendillo, 2006]. However, comparative studies of TEC response during geomagnetic disturbances in solar minimum and solar maximum have not been reported yet. Here we present some new results of TEC enhancements during geomagnetic disturbancesin extreme solar maximum and deep solar minimum. The JPL TEC maps from 12/01/2000 to 12/31/2003 during high solar activity and from 01/01/2007 to 12/31/2010 during low solar activity are used. The deviation of TEC is defined as the differences between TEC and TECq, which represents the 27-day sliding smooth median. The geomagnetic disturbances selected have peaks of geomagnetic index Ap>20. We found that the winter anomaly appears in both extreme solar cycle conditions and has longer-lived patterns than other seasons.The nighttime enhancement is more significant in solar maximum than solar minimum. The mean duration of TEC enhancements is longer in solar minimum than solar maximum. The mean delay at the beginning of positive anomaly responds fastest at around 1500 LT and slowest at around midnight during solar minimum.The mean intensity of enhancements is stronger at higher latitudes and weaker at lower latitudes, and the mean delay is smaller at higher latitudes and larger at lower latitudes in both extreme solar cycle conditions. Acknowledgments: Thiswork was supportedby the National Natural Science Foundation of China under Grants 41204107. We thank JPL and Word Data Center for Geomagnetism at Kyoto University for making available the data. Prolss, G. W., Ionospheric F region storms, in Handbook of Atmospheric Electrodynamics, vol. 2, edited by H. Volland, pp. 195 - 248, CRC Press,Boca Raton, Fla., 1995. Buonsanto, M., Ionospheric storm: A review,Space Science Review, vol. 88, pp. 563 - 601, 1999. Mendillo, M.: Storms in the

  6. Statistical techniques for modeling extreme price dynamics in the energy market

    NASA Astrophysics Data System (ADS)

    Mbugua, L. N.; Mwita, P. N.

    2013-02-01

    Extreme events have large impact throughout the span of engineering, science and economics. This is because extreme events often lead to failure and losses due to the nature unobservable of extra ordinary occurrences. In this context this paper focuses on appropriate statistical methods relating to a combination of quantile regression approach and extreme value theory to model the excesses. This plays a vital role in risk management. Locally, nonparametric quantile regression is used, a method that is flexible and best suited when one knows little about the functional forms of the object being estimated. The conditions are derived in order to estimate the extreme value distribution function. The threshold model of extreme values is used to circumvent the lack of adequate observation problem at the tail of the distribution function. The application of a selection of these techniques is demonstrated on the volatile fuel market. The results indicate that the method used can extract maximum possible reliable information from the data. The key attraction of this method is that it offers a set of ready made approaches to the most difficult problem of risk modeling.

  7. Birthweight Related Factors in Northwestern Iran: Using Quantile Regression Method

    PubMed Central

    Fallah, Ramazan; Kazemnejad, Anoshirvan; Zayeri, Farid; Shoghli, Alireza

    2016-01-01

    Introduction: Birthweight is one of the most important predicting indicators of the health status in adulthood. Having a balanced birthweight is one of the priorities of the health system in most of the industrial and developed countries. This indicator is used to assess the growth and health status of the infants. The aim of this study was to assess the birthweight of the neonates by using quantile regression in Zanjan province. Methods: This analytical descriptive study was carried out using pre-registered (March 2010 - March 2012) data of neonates in urban/rural health centers of Zanjan province using multiple-stage cluster sampling. Data were analyzed using multiple linear regressions andquantile regression method and SAS 9.2 statistical software. Results: From 8456 newborn baby, 4146 (49%) were female. The mean age of the mothers was 27.1±5.4 years. The mean birthweight of the neonates was 3104 ± 431 grams. Five hundred and seventy-three patients (6.8%) of the neonates were less than 2500 grams. In all quantiles, gestational age of neonates (p<0.05), weight and educational level of the mothers (p<0.05) showed a linear significant relationship with the i of the neonates. However, sex and birth rank of the neonates, mothers age, place of residence (urban/rural) and career were not significant in all quantiles (p>0.05). Conclusion: This study revealed the results of multiple linear regression and quantile regression were not identical. We strictly recommend the use of quantile regression when an asymmetric response variable or data with outliers is available. PMID:26925889

  8. Establishment and performance of an experimental green roof under extreme climatic conditions.

    PubMed

    Klein, Petra M; Coffman, Reid

    2015-04-15

    Green roofs alter the surface energy balance and can help in mitigating urban heat islands. However, the cooling of green roofs due to evapotranspiration strongly depends on the climatic conditions, and vegetation type and density. In the Southern Central Plains of the United States, extreme weather events, such as high winds, heat waves and drought conditions pose challenges for successful implementation of green roofs, and likely alter their standard performance. The National Weather Center Experimental Green Roof, an interdisciplinary research site established in 2010 in Norman, OK, aimed to investigate the ecological performance and surface energy balance of green roof systems. Starting in May 2010, 26 months of vegetation studies were conducted and the radiation balance, air temperature, relative humidity, and buoyancy fluxes were monitored at two meteorological stations during April-October 2011. The establishment of a vegetative community trended towards prairie plant dominance. High mortality of succulents and low germination of grasses and herbaceous plants contributed to low vegetative coverage. In this condition succulent diversity declined. Bouteloua gracilis and Delosperma cooperi showed typological dominance in harsh climatic conditions, while Sedum species experienced high mortality. The plant community diversified through volunteers such as Euphorbia maculate and Portulaca maculate. Net radiation measured at a green-roof meteorological station was higher than at a control station over the original, light-colored roofing material. These findings indicate that the albedo of the green roof was lower than the albedo of the original roofing material. The low vegetative coverage during the heat and drought conditions in 2011, which resulted in the dark substrate used in the green roof containers being exposed, likely contributed to the low albedo values. Nevertheless, air temperatures and buoyancy fluxes were often lower over the green roof indicating

  9. Solar Wind Interaction with the Martian Upper Atmosphere at Early Mars/Extreme Solar Conditions

    NASA Astrophysics Data System (ADS)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Combi, M. R.

    2014-12-01

    The investigation of ion escape fluxes from Mars, resulting from the solar wind interaction with its upper atmosphere/ionosphere, is important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0 ~ 300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100 km ~ 5 RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model output fields into the 3-D BATS-R-US Mars multi-fluid MHD (MF-MHD) model (100 km ~ 20 RM) that can simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid MHD model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres. This feature allows us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model output fields are used as the input for the multi-fluid MHD model and the M-GITM is used as input into the AMPS exosphere model. In this study, we present M-GITM, AMPS, and MF-MHD calculations (1-way coupled) for 2.5 GYA conditions and/or extreme solar conditions for present day Mars (high solar wind velocities, high solar wind dynamic pressure, and high solar irradiance conditions, etc.). Present day extreme conditions may result in MF-MHD outputs that are similar to 2.5 GYA cases. The crustal field orientations are also considered in this study. By comparing estimates of past ion escape rates with the current ion loss rates to be returned by the MAVEN spacecraft (2013-2016), we can better constrain the

  10. Characterization of Multi-Scale Atmospheric Conditions Associated with Extreme Precipitation in the Transverse Ranges of Southern California

    NASA Astrophysics Data System (ADS)

    Oakley, N.; Kaplan, M.; Ralph, F. M.

    2015-12-01

    The east-west oriented Transverse Ranges of Southern California have historically experienced shallow landslides and debris flows that threaten life and property. Steep topography, soil composition, and frequent wildfires make this area susceptible to mass wasting. Extreme rainfall often acts as a trigger for these events. This work characterizes atmospheric conditions at multiple scales during extreme (>99th percentile) 1-day precipitation events in the major sub-ranges of the Transverse Ranges. Totals from these 1-day events generally exceed the established sub-daily intensity-duration thresholds for shallow landslides and debris flows in this region. Daily extreme precipitation values are derived from both gridded and station-based datasets over the period 1958-2014. For each major sub-range, extreme events are clustered by atmospheric feature and direction of moisture transport. A composite analysis of synoptic conditions is produced for each cluster to create a conceptual model of atmospheric conditions favoring extreme precipitation. The vertical structure of the atmosphere during these extreme events is also examined using observed and modeled soundings. Preliminary results show two atmospheric features to be of importance: 1) closed and cutoff low-pressure systems, areas of counter-clockwise circulation that can produce southerly flow orthogonal to the Transverse Range ridge axes; and 2) atmospheric rivers that transport large quantities of water vapor into the region. In some cases, the closed lows and atmospheric rivers work in concert with each other to produce extreme precipitation. Additionally, there is a notable east-west dipole of precipitation totals during some extreme events between the San Gabriel and Santa Ynez Mountains where extreme values are observed in one range and not the other. The cause of this relationship is explored. The results of this work can help forecasters and emergency responders determine the likelihood that an event will

  11. Fitness to work of astronauts in conditions of action of the extreme emotional factors.

    PubMed

    Prisniakova, L M

    2004-01-01

    The theoretical model for the quantitative determination of influence of a level of emotional exertion on the success of human activity is presented. The learning curves of fixed words in the groups with a different level of the emotional exertion are analyzed. The obtained magnitudes of time constant T depending on a type of the emotional exertion are a quantitative measure of the emotional exertion. Time constants could also be of use for a prediction of the characteristic of fitness to work of an astronaut in conditions of extreme factors. The inverse of the sign of influencing on efficiency of activity of the man is detected. The paper offers a mathematical model of the relation between successful activity and motivations or the emotional exertion (Yerkes-Dodson law). Proposed models can serve by the theoretical basis of the quantitative characteristics of an estimation of activity of astronauts in conditions of the emotional factors at a phase of their selection. Published by Elsevier Ltd on behalf of COSPAR.

  12. Predicting the solubility of gases in Nitrile Butadiene Rubber in extreme conditions using molecular simulation

    NASA Astrophysics Data System (ADS)

    Khawaja, Musab; Molinari, Nicola; Sutton, Adrian; Mostofi, Arash

    In the oil and gas industry, elastomer seals play an important role in protecting sensitive monitoring equipment from contamination by gases - a problem that is exacerbated by the high pressures and temperatures found down-hole. The ability to predict and prevent such permeative failure has proved elusive to-date. Nitrile butadiene rubber (NBR) is a common choice of elastomer for seals due to its resistance to heat and fuels. In the conditions found in the well it readily absorbs small molecular weight gases. How this behaviour changes quantitatively for different gases as a function of temperature and pressure is not well-understood. In this work a series of fully atomistic simulations are performed to understand the effect of extreme conditions on gas solubility in NBR. Widom particle insertion is used to compute solubilities. The importance of sampling and allowing structural relaxation upon compression are highlighted, and qualitatively reasonable trends reproduced. Finally, while at STP it has previously been shown that the solubility of CO2 is higher than that of He in NBR, we observe that under the right circumstances it is possible to reverse this trend.

  13. Neurophysiological and neuropsychological monitoring of fatigue during extreme environmental and driving conditions.

    PubMed

    Moglia, A; Mauri, M; Alfonsi, E; Coblesano, V; Lozza, A; Sinforiani, E; Bono, G

    1997-03-01

    Aim of the present study was to evaluate the modifications of neurophysiological and neuropsychological variables during extreme environmental and driving conditions. Eight subjects (four drivers and four passengers) were evaluated while driving a four wheels drive across the Big West Algerian Erg. The following procedures were carried out in basal conditions and at the end of the 1st, 3rd, and 5th day of driving: surface EMG of masseter and cervical para-spinal muscles during maximum isometric contraction lasting 12 sec; test of simple visual and acoustic reaction times, Cancellation test, Trial Making test. As from the second day, the drivers used appropriate dental plates. In the drivers, EMG spectrum analysis revealed a significant decrease in mean frequency values at the end of the 1st day. This finding was more relevant in masseter muscles. No significant fatigue phenomena were detected on the subsequent controls. On the contrary, the passengers showed a decrease in mean EMG frequency values. No significant modifications in the cognitive variables were detected at the end of the 1st day (initial response to stress), whereas a progressive worsening was observed in the subsequent evaluations. EMG fatigue of masseter muscles seems to be more related to psychic stress. The beneficial effects of the dental plates were also confirmed.

  14. Nutritional condition of Pacific Black Brant wintering at the extremes of their range

    USGS Publications Warehouse

    Mason, D.D.; Barboza, P.S.; Ward, D.H.

    2006-01-01

    Endogenous stores of energy allow birds to survive periods of severe weather and food shortage during winter. We documented changes in lipid, protein, moisture, and ash in body tissues of adult female Pacific Black Brant (Branta bernicla nigricans) and modeled the energetic costs of wintering. Birds were collected at the extremes of their winter range, in Alaska and Baja California, Mexico. Body lipids decreased over winter for birds in Alaska but increased for those in Baja California. Conversely, body protein increased over winter for Brant in Alaska and remained stable for birds in Baja California. Lipid stores likely fuel migration for Brant wintering in Baja California and ensure winter survival for those in Alaska. Increases in body protein may support earlier reproduction for Brant in Alaska. Predicted energy demands were similar between sites during late winter but avenues of expenditure were different. Birds in Baja California spent more energy on lipid synthesis while those in Alaska incurred higher thermoregulatory costs. Estimated daily intake rates of eelgrass were similar between sites in early winter; however, feeding time was more constrained in Alaska because of high tides and short photoperiods. Despite differences in energetic costs and foraging time, Brant wintering at both sites appeared to be in good condition. We suggest that wintering in Alaska may be more advantageous than long-distance migration if winter survival is similar between sites and constraints on foraging time do not impair body condition. ?? The Cooper Ornithological Society 2006.

  15. Regional metamorphism at extreme conditions: Implications for orogeny at convergent plate margins

    NASA Astrophysics Data System (ADS)

    Zheng, Yong-Fei; Chen, Ren-Xu

    2017-09-01

    Regional metamorphism at extreme conditions refers either to Alpine-type metamorphism at low geothermal gradients of <10 °C/km, or to Buchan-type metamorphism at high geothermal gradients of >30 °C/km. Extreme pressures refer to those above the polymorphic transition of quartz to coesite, so that ultrahigh-pressure (UHP) eclogite-facies metamorphism occurs at mantle depths of >80 km. Extreme temperatures refer to those higher than 900 °C at crustal depths of ≤80 km, so that ultrahigh-temperature (UHT) granulite-facies metamorphism occurs at medium to high pressures. While crustal subduction at the low geothermal gradients results in blueschist-eclogite facies series without arc volcanism, heating of the thinned orogenic lithosphere brings about the high geothermal gradients for amphibolite-granulite facies series with abundant magmatism. Therefore, UHP metamorphic rocks result from cold lithospheric subduction to the mantle depths, whereas UHT metamorphic rocks are produced by hot underplating of the asthenospheric mantle at the crustal depths. Active continental rifting is developed on the thinned lithosphere in response to asthenospheric upwelling, and this tectonism is suggested as a feasible mechanism for regional granulite-facies metamorphism, with the maximum temperature depending on the extent to which the mantle lithosphere is thinned prior to the rifting. While lithospheric compression is associated with subduction metamorphism in accretionary and collisional orogens, the thinned orogenic lithosphere undergoes extension due to the asthenospheric upwelling to result in orogen-parallel rifting metamorphism and magmatism. Thus, the rifting metamorphism provides a complement to the subduction metamorphism and its operation marks the asthenospheric heating of the orogenic lithosphere. Because of the partial melting and melt extraction of the lower continental crust, contemporaneous granite-migmatite-granulite associations may serve as a petrological

  16. Aerobic carboxydotrophy under extremely haloalkaline conditions in Alkalispirillum/Alkalilimnicola strains isolated from soda lakes.

    PubMed

    Sorokin, Dimitry Yu; Tourova, Tatjana P; Kovaleva, Olga L; Kuenen, J Gijs; Muyzer, Gerard

    2010-03-01

    Aerobic enrichments from soda lake sediments with CO as the only substrate resulted in the isolation of five bacterial strains capable of autotrophic growth with CO at extremely high pH and salinity. The strains belonged to the Alkalispirillum/Alkalilimnicola cluster in the Gammaproteobacteria, where the ability to oxidize CO, but not growth with CO, has been demonstrated previously. The growth with CO was possible only at an oxygen concentration below 5 % and CO concentration below 20 % in the gas phase. The isolates were also capable of growth with formate but not with H(2). The carboxydotrophic growth occurred within a narrow pH range from 8 to 10.5 (optimum at 9.5) and a broad salt concentration from 0.3 to 3.5 M total Na(+) (optimum at 1.0 M). Cells grown on CO had high respiration activity with CO and formate, while the cells grown on formate actively oxidized formate alone. In CO-grown cells, CO-dehydrogenase (CODH) activity was detectable both in soluble and membrane fractions, while the NAD-independent formate dehydrogenase (FDH) resided solely in membranes. The results of total protein profiling and the failure to detect CODH with conventional primers for the coxL gene indicated that the CO-oxidizing enzyme in haloalkaliphilic isolates might differ from the classical aerobic CODH complex. A single cbbL gene encoding the RuBisCO large subunit was detected in all strains, suggesting the presence of the Calvin cycle of inorganic carbon fixation. Overall, these results demonstrated the possibility of aerobic carboxydotrophy under extremely haloalkaline conditions.

  17. Spring Ephemerals Adapt to Extremely High Light Conditions via an Unusual Stabilization of Photosystem II

    PubMed Central

    Tu, Wenfeng; Li, Yang; Liu, Wu; Wu, Lishuan; Xie, Xiaoyan; Zhang, Yuanming; Wilhelm, Christian; Yang, Chunhong

    2016-01-01

    Ephemerals, widely distributed in the Gobi desert, have developed significant characteristics to sustain high photosynthetic efficiency under high light (HL) conditions. Since the light reaction is the basis for photosynthetic conversion of solar energy to chemical energy, the photosynthetic performances in thylakoid membrane of the spring ephemerals in response to HL were studied. Three plant species, namely two C3 spring ephemeral species of Cruciferae: Arabidopsis pumila (A. pumila) and Sisymbrium altissimum (S. altissimum), and the model plant Arabidopsis thaliana (A. thaliana) were chosen for the study. The ephemeral A. pumila, which is genetically close to A. thaliana and ecologically in the same habitat as S. altissimum, was used to avoid complications arising from the superficial differences resulted from comparing plants from two extremely contrasting ecological groups. The findings manifested that the ephemerals showed significantly enhanced activities of photosystem (PS) II under HL conditions, while the activities of PSII in A. thaliana were markedly decreased under the same conditions. Detailed analyses of the electron transport processes revealed that the increased plastoquinone pool oxidization, together with the enhanced PSI activities, ensured a lowered excitation pressure to PSII of both ephemerals, and thus facilitated the photosynthetic control to avoid photodamage to PSII. The analysis of the reaction centers of the PSs, both in terms of D1 protein turnover kinetics and the long-term adaptation, revealed that the unusually stable PSs structure provided the basis for the ephemerals to carry out high photosynthetic performances. It is proposed that the characteristic photosynthetic performances of ephemerals were resulted from effects of the long-term adaptation to the harsh environments. PMID:26779223

  18. Surf zone, infragravity wave energy flux, and runup in extreme conditions

    NASA Astrophysics Data System (ADS)

    Fiedler, J. W.; Brodie, K. L.; McNinch, J.; Guza, R. T.

    2014-12-01

    Waves, currents, and sand levels were observed on a 1.4 km-long cross-shore transect extending from the back beach to ~11 m water depth at Agate Beach, Oregon in Fall 2013. Wave runup and water table fluctuations on this low slope (1:80) beach were measured with a cliff-mounted scanning Lidar and buried pressure sensors. Significant wave heights at an offshore buoy in 128m depth ranged from small (0.5m) to extreme (7.5m), with peak periods between 4-22 seconds. Infragravity frequency (nominally 0.01 Hz) horizontal runup excursions exceeded 100m, and infragravity cross-shore velocity exceeded 3 m/s. Cross-shore patterns of infragravity wave energy flux, observed with seven co-located pressure and current meters, indicate 'proto-saturation' of the inner surfzone in extreme conditions. That is, the intensification of incident wave forcing (e.g. higher energy, longer swell) leads to a wider surfzone and an increase in the shoreward infragravity wave energy seaward of the surfzone, but produces more modest increases in flux in the inner surfzone, and in the runup. Nonlinear energy balances, based on the observations, show transfer of energy from sea-swell to infragravity waves, and vice-versa. The infragravity energy balance closes in cases with low energy incident sea-swell. With more energetic incident waves, there is an unexplained inner surfzone energy sink at the lowest IG frequencies (0.004-0.02 Hz). Ongoing work aims to quantify the effect on infragravity energy balances by infragravity wave breaking and bottom friction. Additionally, the estimates may be degraded by contamination with rotational velocities of surfzone eddies. Whatever the dynamical explanation, infragravity wave runup on a low slope beach in high-energy conditions is limited significantly by dissipation. The slow rate of runup increase suggests nascent, or 'proto' saturation. This work was supported by the U.S. Army Corps of Engineers.

  19. 360⁰ -View of Quantum Theory and Ab Initio Simulation at Extreme Conditions: 2014 Sanibel Symposium

    SciTech Connect

    Cheng, Hai-Ping

    2016-09-02

    The Sanibel Symposium 2014 was held February 16-21, 2014, at the King and Prince, St. Simons Island, GA. It was successful in bringing condensed-matter physicists and quantum chemists together productively to drive the emergence of those specialties. The Symposium had a significant role in preparing a whole generation of quantum theorists. The 54th Sanibel meeting looked to the future in two ways. We had 360⁰-View sessions to honor the exceptional contributions of Rodney Bartlett (70), Bill Butler (70), Yngve Öhrn (80), Fritz Schaefer (70), and Malcolm Stocks (70). The work of these five has greatly impacted several generations of quantum chemists and condensed matter physicists. The “360⁰” is the sum of their ages. More significantly, it symbolizes a panoramic view of critical developments and accomplishments in theoretical and computational chemistry and physics oriented toward the future. Thus, two of the eight 360⁰-View sessions focused specifically on younger scientists. The 360⁰-View program was the major component of the 2014 Sanibel meeting. Another four sessions included a sub-symposium on ab initio Simulations at Extreme Conditions, with focus on getting past the barriers of present-day Born-Oppenheimer molecular dynamics by advances in finite-temperature density functional theory, orbital-free DFT, and new all-numerical approaches.

  20. Synchrotron radiation and high pressure: new light on materials under extreme conditions.

    PubMed

    Hemley, Russell J; Mao, Ho-kwang; Struzhkin, Viktor V

    2005-03-01

    With the steady development of static high-pressure techniques in recent years, it is now possible to probe in increasing detail the novel behavior of materials subjected to extreme conditions of multimegabar pressures (>300 GPa) and temperatures from cryogenic states to thousands of degrees. By and large, the growth in this area has been made possible by accelerating developments in diamond-anvil cell methods coupled with new synchrotron radiation techniques. Significant advances have occurred in high-pressure powder and single-crystal diffraction, spectroscopy, inelastic scattering, radiography, and infrared spectroscopy. A brief overview of selected highlights in each of these classes of experiments is presented that illustrate both the state-of-the-art as well as current technical and scientific challenges. The experiments have been made possible by the development of a spectrum of new techniques at both third- and second-generation high-energy sources together with key advances in high-pressure technology. The results have implications for a variety of problems in physics, chemistry, materials science, geoscience, planetary science, and biology.

  1. Smell-taste dysfunctions in extreme weight/eating conditions: analysis of hormonal and psychological interactions.

    PubMed

    Fernández-Aranda, Fernando; Agüera, Zaida; Fernández-García, Jose C; Garrido-Sanchez, Lourdes; Alcaide-Torres, Juan; Tinahones, Francisco J; Giner-Bartolomé, Cristina; Baños, Rosa M; Botella, Cristina; Cebolla, Ausias; de la Torre, Rafael; Fernández-Real, Jose M; Ortega, Francisco J; Frühbeck, Gema; Gómez-Ambrosi, Javier; Granero, Roser; Islam, Mohamed A; Jiménez-Murcia, Susana; Tárrega, Salomé; Menchón, José M; Fagundo, Ana B; Sancho, Carolina; Estivill, Xavier; Treasure, Janet; Casanueva, Felipe F

    2016-02-01

    (1) The objective of this study is to analyze differences in smell-taste capacity between females in extreme weight/eating conditions (EWC) and (2) to explore the interaction between smell/taste capacity, gastric hormones, eating behavior and body mass index (BMI). The sample comprised 239 females in EWC [64 Anorexia nervosa (AN) and 80 age-matched healthy-weight controls, and 59 obese and 36 age-matched healthy-weight controls]. Smell and taste assessments were performed through "Sniffin' Sticks" and "Taste Strips," respectively. The assessment measures included the eating disorders inventory-2, the symptom check list 90-revised, and The Dutch Eating Behavior Questionnaire, as well as peptides from the gastrointestinal tract [Ghrelin, peptide YY, cholecystokinin]. Smell capacity was differentially associated across EWC groups. Smell was clearly impaired in obese participants and increased in AN (hyposmia in Obesity was 54.3 and 6.4 % in AN), but taste capacity did not vary across EWC. Ghrelin levels were significantly decreased in obese subjects and were related to smell impairment. EWC individuals showed a distinct smell profile and circulating ghrelin levels compared to controls. Smell capacity and ghrelin may act as moderators of emotional eating and BMI.

  2. Modeling of the Human - Operator in a Complex System Functioning Under Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Getzov, Peter; Hubenova, Zoia; Yordanov, Dimitar; Popov, Wiliam

    2013-12-01

    Problems, related to the explication of sophisticated control systems of objects, operating under extreme conditions, have been examined and the impact of the effectiveness of the operator's activity on the systems as a whole. The necessity of creation of complex simulation models, reflecting operator's activity, is discussed. Organizational and technical system of an unmanned aviation complex is described as a sophisticated ergatic system. Computer realization of main subsystems of algorithmic system of the man as a controlling system is implemented and specialized software for data processing and analysis is developed. An original computer model of a Man as a tracking system has been implemented. Model of unmanned complex for operators training and formation of a mental model in emergency situation, implemented in "matlab-simulink" environment, has been synthesized. As a unit of the control loop, the pilot (operator) is simplified viewed as an autocontrol system consisting of three main interconnected subsystems: sensitive organs (perception sensors); central nervous system; executive organs (muscles of the arms, legs, back). Theoretical-data model of prediction the level of operator's information load in ergatic systems is proposed. It allows the assessment and prediction of the effectiveness of a real working operator. Simulation model of operator's activity in takeoff based on the Petri nets has been synthesized.

  3. Radar observations of magnetospheric activity during extremely quiet solar wind conditions

    NASA Astrophysics Data System (ADS)

    Walker, A. D. M.; Baker, K. B.; Pinnock, M.; Dudeney, J. R.; Rash, J. P. S.

    2002-04-01

    During a period of extremely quiet solar wind conditions from 8 to 10 March 1997, strong activity was observed by the Southern Hemisphere Auroral Radar Experiment Super Dual Auroral Radar Network radars in the Antarctic premidnight ionosphere. This activity took the form of quasiperiodic flow bursts with ionospheric drift velocities exceeding 2 km s-1. Data from the Satellite Experiments Simultaneous with Antarctic Measurements (SESAME) automated geophysical observatories in Antarctica and Defense Meteorological Satellite Program and Polar satellites are used with the radar data to study the convection flow in the southern polar ionosphere at the time of these flow bursts. The study shows that the bursts occurred with an approximate period of 12 min. Their direction was westward, and they were superimposed on a background westward flow. In the premidnight sector this is interpreted as a flow associated with dipolarization of the magnetotail tail field. There is a band of strong particle precipitation associated with the flow bursts. The location suggests that they occur deep in the magnetotail and cannot be associated with any lobe reconnection. They are at a latitude near the region where a viscously driven convection cell is expected to exist, and their sense is that of the return convection flow in such a cell. The results suggest that there is an internal magnetospheric mechanism for sporadic energy release in the magnetotail that need not be associated with changes in solar wind reconnection on the magnetopause.

  4. Characteristics of the global ionospheric electron density during the extreme solar minimum condition

    NASA Astrophysics Data System (ADS)

    Jee, G.

    2010-12-01

    The last solar minimum period between the cycles 23 and 24 was anomalously low and lasted long compared with previous solar minimums. The resulting solar irradiance received in the Earth’s upper atmosphere was extremely low and therefore it can readily be expected that the upper atmosphere should be greatly affected by this low solar activity. There were several studies on this effect but many of them was on the thermosphere (Solomon et al., 2010; Emmert et al., 2010). According to these studies, the thermospheric temperature was cooler and the density was lower than the previous solar minimum periods. The low solar irradiance during the last solar minimum should also affect the ionosphere, not only via the lower ion-electron production due to the lower EUV radiation but also through the interactions with the thermosphere that was already influenced by the low solar irradiance. In this study, we utilized the measurements of total electron content (TEC) from the TOPEX and JASON satellites during the periods of 1992 to 2010, which includes the last two solar minimums, in order to investigate the differences between the ionospheric behaviors during the two minimum conditions. Initially the levels of the global ionization will be examined during these minimum periods and then further discussions will be continued on the details of the ionospheric behavior such as the seasonal and storm-time variations.

  5. Phase transition and chemical decomposition of liquid carbon dioxide and nitrogen mixture under extreme conditions

    NASA Astrophysics Data System (ADS)

    Xiao-Xu, Jiang; Guan-Yu, Chen; Yu-Tong, Li; Xin-Lu, Cheng; Cui-Ming, Tang

    2016-02-01

    Thermodynamic and chemical properties of liquid carbon dioxide and nitrogen (CO2-N2) mixture under the conditions of extremely high densities and temperatures are studied by using quantum molecular dynamic (QMD) simulations based on density functional theory including dispersion corrections (DFT-D). We present equilibrium properties of liquid mixture for 112 separate density and temperature points, by selecting densities ranging from ρ = 1.80 g/cm3 to 3.40 g/cm3 and temperatures from T = 500 K to 8000 K. In the range of our study, the liquid CO2-N2 mixture undergoes a continuous transition from molecular to atomic fluid state and liquid polymerization inferred from pair correlation functions (PCFs) and the distribution of various molecular components. The insulator-metal transition is demonstrated by means of the electronic density of states (DOS). Project supported by the National Natural Science Foundation of China (Grant Nos. 11374217, 11135012, and 11375262) and the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. 11176020).

  6. Lorenz-Mie digital holographic microscopy on complex colloids and at extreme pressure conditions (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Saglimbeni, Filippo; Bianchi, Silvio; Di Leonardo, Roberto; Padgett, Miles J.; Gibson, Graham; Bowman, Richard W.; Paradossi, Gaio

    2016-03-01

    Lorenz-Mie scattering theory allows to predict the field scattered by spherical objects illuminated by coherent light. By fitting the fringe pattern resulting from the interference of incident and scattered light, it is possible to track and size colloidal particles with a few nanometer precision. Using digital holographic microscopy (DHM) we extend the applications of Lorenz-Mie theory to hollow spherical structures and to extremely high pressure conditions. On the one hand, we geometrically and optically characterize complex colloids as polymer-shelled microbubbles, with high precision, low costs and short acquisition time. These microbubbles are likely to be unique tools for targeted drug delivery and are currently used as contrast agents for sonography. We measured size, shell thickness and refractive index for hundreds of polymeric microbubbles showing that shell thickness displays a large variation that is strongly correlated with its refractive index and thus with its composition. On the other hand we demonstrate that DHM can be used for accurate 3D tracking and sizing of a holographically trapped colloidal probe in a diamond anvil cell (DAC). Polystyrene beads were trapped in water up to Gigapascal pressures while simultaneously recording in-line holograms at 1 KHz frame rate. This technique may potentially provide a new method for spatially resolved pressure measurements inside a DAC.

  7. Robust and efficient estimation with weighted composite quantile regression

    NASA Astrophysics Data System (ADS)

    Jiang, Xuejun; Li, Jingzhi; Xia, Tian; Yan, Wanfeng

    2016-09-01

    In this paper we introduce a weighted composite quantile regression (CQR) estimation approach and study its application in nonlinear models such as exponential models and ARCH-type models. The weighted CQR is augmented by using a data-driven weighting scheme. With the error distribution unspecified, the proposed estimators share robustness from quantile regression and achieve nearly the same efficiency as the oracle maximum likelihood estimator (MLE) for a variety of error distributions including the normal, mixed-normal, Student's t, Cauchy distributions, etc. We also suggest an algorithm for the fast implementation of the proposed methodology. Simulations are carried out to compare the performance of different estimators, and the proposed approach is used to analyze the daily S&P 500 Composite index, which verifies the effectiveness and efficiency of our theoretical results.

  8. Characterization of Extremely Low Frequency Magnetic Fields from Diesel, Gasoline and Hybrid Cars under Controlled Conditions

    PubMed Central

    Hareuveny, Ronen; Sudan, Madhuri; Halgamuge, Malka N.; Yaffe, Yoav; Tzabari, Yuval; Namir, Daniel; Kheifets, Leeka

    2015-01-01

    This study characterizes extremely low frequency (ELF) magnetic field (MF) levels in 10 car models. Extensive measurements were conducted in three diesel, four gasoline, and three hybrid cars, under similar controlled conditions and negligible background fields. Averaged over all four seats under various driving scenarios the fields were lowest in diesel cars (0.02 μT), higher for gasoline (0.04–0.05 μT) and highest in hybrids (0.06–0.09 μT), but all were in-line with daily exposures from other sources. Hybrid cars had the highest mean and 95th percentile MF levels, and an especially large percentage of measurements above 0.2 μT. These parameters were also higher for moving conditions compared to standing while idling or revving at 2500 RPM and higher still at 80 km/h compared to 40 km/h. Fields in non-hybrid cars were higher at the front seats, while in hybrid cars they were higher at the back seats, particularly the back right seat where 16%–69% of measurements were greater than 0.2 μT. As our results do not include low frequency fields (below 30 Hz) that might be generated by tire rotation, we suggest that net currents flowing through the cars’ metallic chassis may be a possible source of MF. Larger surveys in standardized and well-described settings should be conducted with different types of vehicles and with spectral analysis of fields including lower frequencies due to magnetization of tires. PMID:25647323

  9. Characterization of extremely low frequency magnetic fields from diesel, gasoline and hybrid cars under controlled conditions.

    PubMed

    Hareuveny, Ronen; Sudan, Madhuri; Halgamuge, Malka N; Yaffe, Yoav; Tzabari, Yuval; Namir, Daniel; Kheifets, Leeka

    2015-01-30

    This study characterizes extremely low frequency (ELF) magnetic field (MF) levels in 10 car models. Extensive measurements were conducted in three diesel, four gasoline, and three hybrid cars, under similar controlled conditions and negligible background fields. Averaged over all four seats under various driving scenarios the fields were lowest in diesel cars (0.02 μT), higher for gasoline (0.04-0.05 μT) and highest in hybrids (0.06-0.09 μT), but all were in-line with daily exposures from other sources. Hybrid cars had the highest mean and 95th percentile MF levels, and an especially large percentage of measurements above 0.2 μT. These parameters were also higher for moving conditions compared to standing while idling or revving at 2500 RPM and higher still at 80 km/h compared to 40 km/h. Fields in non-hybrid cars were higher at the front seats, while in hybrid cars they were higher at the back seats, particularly the back right seat where 16%-69% of measurements were greater than 0.2 μT. As our results do not include low frequency fields (below 30 Hz) that might be generated by tire rotation, we suggest that net currents flowing through the cars' metallic chassis may be a possible source of MF. Larger surveys in standardized and well-described settings should be conducted with different types of vehicles and with spectral analysis of fields including lower frequencies due to magnetization of tires.

  10. Methanogenesis at extremely haloalkaline conditions in the soda lakes of Kulunda Steppe (Altai, Russia).

    PubMed

    Sorokin, Dimitry Y; Abbas, Ben; Geleijnse, Mitchell; Pimenov, Nikolai V; Sukhacheva, Marina V; van Loosdrecht, Mark C M

    2015-04-01

    Microbial methanogenesis at extreme conditions of saline alkaline soda lakes has, so far, been poorly investigated. Despite the obvious domination of sulfidogenesis as the therminal anaerobic process in the hypersaline soda lakes of Kulunda Steppe (Altai, southwestern Siberia), high concentrations of methane were detected in the anaerobic sediments. Potential activity measurements with different substrates gave results significantly deviating from what is commonly found in hypersaline habitats with neutral pH. In particular, not only a non-competitive methylotrophic pathway was active, but also lithotrophic and, in some cases, even acetate-dependent methanogenesis was found to be present in hypersaline soda lake sediments. All three pathways were functioning exclusively within the alkaline pH range between 8 and 10.5, while the salt concentration was the key factor influencing the activity. Methylotrophic and, to a lesser extent, lithotrophic methanogenesis were active up to soda-saturating conditions (4 M total Na(+)). Acetate-dependent methanogenesis was observed at salinities below 3 M total Na(+). Detection of methanogens in sediments using the mcrA gene as a functional marker demonstrated domination of methylotrophic genera Methanolobus and Methanosalsum and lithotrophic Methanocalculus. In a few cases, acetoclastic Methanosaeta was detected, as well as two deep lineage methanogens. Cultivation results corresponded well to the mcrA-based observations. Enrichments for natronophilic methylotrophic methanogens resulted in isolation of Methanolobus strains at moderate salinity, while at salt concentrations above 2 M Na(+) a novel member of the genus Methanosalsum was dominating. Enrichments with H2 or formate invariably resulted in domination of close relatives of Methanocalculus natronophilus. Enrichments with acetate at low salt concentration yielded two acetoclastic alkaliphilic Methanosaeta cultures, while at salinity above 1 M Na(+) syntrophic associations

  11. Trace element partitioning between vapor, brine and halite under extreme phase separation conditions

    NASA Astrophysics Data System (ADS)

    Foustoukos, D. I.; Seyfried, W. E.

    2007-04-01

    Experiments were conducted to investigate the partitioning of Li, Br, Rb, Cs and B between vapor, brine and halite during subcritical and supercritical phase separation in the NaCl-H 2O system (388-550 °C, 250-350 bars). Results indicate that Li and Br partition preferentially into the low-salinity vapor fluids, while Rb and Cs become more enriched in the coexisting brines. Under more extreme conditions of pressure and temperature in the two-phase region, especially near the vapor-brine-halite boundary, strong salting-out effects imposed on neutral aqueous species enhance significantly partitioning of all trace elements into the low-salinity fluid. Dissolved boron is strongly affected by this and a particularly strong enrichment into vapors is observed, a trend that can be effectively correlated with changes in reduced density. Exclusion of Li, Br, Rb, Cs and B from halite, when precipitated, further increases the solubility of these species in the coexisting Cl-poor fluid. In general, the lack of distortion in the partitioning behavior of trace elements between vapor, brine and/or halite with the transition from subcritical to supercritical conditions in the NaCl-H 2O system precludes the need for special reference to the critical point of seawater when interpreting phase relations in submarine hydrothermal systems. The combination of experimentally determined trace element partitioning data with constraints imposed by mineral solubility provides a means to better understand the origin and evolution of hot spring vent fluids. For example, in Brandon hydrothermal system (21°S EPR) supercritical phase separation and subseafloor mixing appear to be the main heat and mass transport mechanisms fueled by a shallow magmatic intrusion, with boron systematics ruling out major contributions from magmatic degassing processes accompanying the near-seafloor volcanism.

  12. CHANGE IN PREVALENCE OF CHRONIC CONDITIONS BETWEEN CHILDHOOD AND ADOLESCENCE AMONG EXTREMELY LOW BIRTH WEIGHT CHILDREN

    PubMed Central

    Hack, Maureen; Schluchter, Mark; Andreias, Laura; Margevicius, Seunghee; Taylor, H. Gerry; Drotar, Dennis; Cuttler, Leona

    2013-01-01

    Context Extremely low birth weight (ELBW, <1kg) children have high rates of chronic conditions during childhood. Information on their trajectory of health during the critical period of adolescence is needed for health care planning. Objective To examine changes in rates of chronic conditions between age 8 and 14 years among ELBW compared to normal birth weight (NBW) controls. Design, Setting and Participants Cohort study conducted from 2004 through2009 of 181 ELBW children (weight <1kg) and 115 NBW controls of similar sociodemographic status born 1992 through 1995 in Cleveland, Ohio. Main Outcome Measures Rates of chronic conditions overall (measured with the revised Questionnaire for Identifying Children with Chronic Conditions) and rates of asthma and obesity. Results The overall rates of chronic conditions did not change significantly between ages 8 and 14 years among ELBW children (75% at age 8 years vs 74% at age 14 years) or NBW controls (37% at 8 years vs 47% at age 14 years). In generalized estimating equations logistic regression, adjusting for sociodemographic status, sex and race, ELBW continued to have higher rates of chronic conditions than NBW controls at age 14 years (74% vs 47%, respectively adjusted odds ratio [AOR],2.8; 95% Confidence Interval {CI},1.7 to 4.6). Rates of asthma requiring medication did not change between 8 and 14 years among ELBW children (23% at both ages), but increased among NBW children from 8% at age 8 years to 17% at age 14 years (p=0.002). Differences in rates of asthma between ELBW and NBW children were no longer significant at the age of 14 years (23% vs 17%, respectively; AOR,1.5; [95%CI,0.8 to 2.8]. Mean z scores for body mass index increased in ELBW children from 0.06 at age 8 yesrs to 0.38 at age 14 years(p<0.001) and rates of obesity increased from 12% at age 8 years to 19% at age 14 years (p=0.02). However, the scores and rates did not change among NBW controls such that at the age of 14 years the differences between

  13. Physiological Responses to Firefighting in Extreme Temperatures Do Not Compare to Firefighting in Temperate Conditions

    PubMed Central

    Windisch, Stephanie; Seiberl, Wolfgang; Hahn, Daniel; Schwirtz, Ansgar

    2017-01-01

    Purpose: The aim of this study was to examine physiological responses to two different simulated firefighting exercises: a firefighting exercise with flashovers, smoke, poor visibility and extreme temperatures (300°) in a burning container and a standard firefighting exercise in temperate conditions. Furthermore, a second purpose of the study was to find out if the contribution of strength and endurance capacities to firefighting performance changes when the demands of the firefighting exercise change. Methods: Sixteen professional firefighters performed a maximum treadmill test, strength testing, a standard simulated firefighting exercise (SFE) without heat and flashovers and a firefighting exercise with a simulation of the flashover phenomenon in a burning container (FOT). The treadmill testing was used to determine peak oxygen uptake (VO2peak), ventilatory threshold (VT1) and respiratory compensation point (RCP). Three intensity zones were identified according to heart rate (HR) values corresponding to VT1 and RCP: zone 1–HR below VT1, zone 2-HR between VT1 and RCP, zone 3–HR above RCP. Firefighting performance was determined by a simple time-strain-air depletion model (TSA) taking the sum of z-transformed parameters of time to finish the exercise, strain in terms of mean heart rate, and air depletion from the breathing apparatus. Correlations were then established between TSA based firefighting performance parameters and fitness variables representing strength and endurance. Results: HR was significantly lower during SFE (79.9 ± 6.9%HRmax) compared to FOT (85.4 ± 5.2%HRmax). During SFE subjects spent 24.6 ± 30.2% of time in zone 1, 65.8 ± 28.1% in zone 2 and 9.7 ± 16.6% in zone 3. During FOT subjects spent 16.3 ± 12.8% in zone 1, 50.4 ± 13.2% in zone 2 and 33.3 ± 16.6% in zone 3. Out of all correlations, relative VO2peak showed the highest relation to mean HR during SFE (−0.593) as well as FOT (−0.693). Conclusions: Endurance in terms of VO2

  14. Physiological Responses to Firefighting in Extreme Temperatures Do Not Compare to Firefighting in Temperate Conditions.

    PubMed

    Windisch, Stephanie; Seiberl, Wolfgang; Hahn, Daniel; Schwirtz, Ansgar

    2017-01-01

    Purpose: The aim of this study was to examine physiological responses to two different simulated firefighting exercises: a firefighting exercise with flashovers, smoke, poor visibility and extreme temperatures (300°) in a burning container and a standard firefighting exercise in temperate conditions. Furthermore, a second purpose of the study was to find out if the contribution of strength and endurance capacities to firefighting performance changes when the demands of the firefighting exercise change. Methods: Sixteen professional firefighters performed a maximum treadmill test, strength testing, a standard simulated firefighting exercise (SFE) without heat and flashovers and a firefighting exercise with a simulation of the flashover phenomenon in a burning container (FOT). The treadmill testing was used to determine peak oxygen uptake (VO2peak), ventilatory threshold (VT1) and respiratory compensation point (RCP). Three intensity zones were identified according to heart rate (HR) values corresponding to VT1 and RCP: zone 1-HR below VT1, zone 2-HR between VT1 and RCP, zone 3-HR above RCP. Firefighting performance was determined by a simple time-strain-air depletion model (TSA) taking the sum of z-transformed parameters of time to finish the exercise, strain in terms of mean heart rate, and air depletion from the breathing apparatus. Correlations were then established between TSA based firefighting performance parameters and fitness variables representing strength and endurance. Results: HR was significantly lower during SFE (79.9 ± 6.9%HRmax) compared to FOT (85.4 ± 5.2%HRmax). During SFE subjects spent 24.6 ± 30.2% of time in zone 1, 65.8 ± 28.1% in zone 2 and 9.7 ± 16.6% in zone 3. During FOT subjects spent 16.3 ± 12.8% in zone 1, 50.4 ± 13.2% in zone 2 and 33.3 ± 16.6% in zone 3. Out of all correlations, relative VO2peak showed the highest relation to mean HR during SFE (-0.593) as well as FOT (-0.693). Conclusions: Endurance in terms of VO2peak is an

  15. Assessment extreme hydrometeorological conditions in the Gulf of Bothnia, the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Dvornikov, Anton; Martyanov, Stanislav; Ryabchenko, Vladimir; Eremina, Tatjana; Isaev, Alexey; Sein, Dmitry

    2017-04-01

    Extreme hydrometeorological conditions in the Gulf of Bothnia, the Baltic Sea, are estimated paying a special attention to the area of the future construction of nuclear power plant (NPP) "Hanhikivi-1" (24° 16' E, 64° 32' N). To produce these estimates, long-term observations and results from numerical models of water and ice circulation and wind waves are used. It is estimated that the average annual air temperature in the vicinity of the station is +3° C, summer and winter extreme temperature is equal to 33.3° C and -41.5° C, respectively. Model calculations of wind waves have shown that the most dangerous (in terms of the generation of wind waves in the NPP area) is a north-west wind with the direction of 310°. The maximum height of the waves in the Gulf of Bothnia near the NPP for this wind direction with wind velocity of 10 m/s is 1.2-1.4 m. According to the model estimates, the highest possible level of the sea near the NPP is 248 cm, the minimum level, -151 cm, respectively for the western and eastern winds. These estimates are in good agreement with observations on the sea level for the period 1922-2015 at the nearest hydrometeorological station Raahe (Finland). In order to assess the likely impact of the NPP on the marine environment numerical experiments for the cold (2010) and warm year (2014) have been carried out. These calculations have shown that permanent release of heat into the marine environment from the operating NPP for the cold year (2010) will increase the temperature in the upper layer of 0-250m zone by 10°C in winter - spring and by 8°C in summer - early autumn, and in the bottom layer of 0-250m zone by 5°C in winter - spring and 3°C in summer - early autumn. For the warm year (2014), these temperature changes are smaller. Ice cover in both cases will disappear in two - kilometer vicinity of the NPP. These effects should be taken into account when assessing local climate changes in the future

  16. Structural and Mechanical Properties of Intermediate Filaments under Extreme Conditions and Disease

    NASA Astrophysics Data System (ADS)

    Qin, Zhao

    Intermediate filaments are one of the three major components of the cytoskeleton in eukaryotic cells. It was discovered during the recent decades that intermediate filament proteins play key roles to reinforce cells subjected to large-deformation as well as participate in signal transduction. However, it is still poorly understood how the nanoscopic structure, as well as the biochemical properties of these protein molecules contribute to their biomechanical functions. In this research we investigate the material function of intermediate filaments under various extreme mechanical conditions as well as disease states. We use a full atomistic model and study its response to mechanical stresses. Learning from the mechanical response obtained from atomistic simulations, we build mesoscopic models following the finer-trains-coarser principles. By using this multiple-scale model, we present a detailed analysis of the mechanical properties and associated deformation mechanisms of intermediate filament network. We reveal the mechanism of a transition from alpha-helices to beta-sheets with subsequent intermolecular sliding under mechanical force, which has been inferred previously from experimental results. This nanoscale mechanism results in a characteristic nonlinear force-extension curve, which leads to a delocalization of mechanical energy and prevents catastrophic fracture. This explains how intermediate filament can withstand extreme mechanical deformation of > 1 00% strain despite the presence of structural defects. We combine computational and experimental techniques to investigate the molecular mechanism of Hutchinson-Gilford progeria syndrome, a premature aging disease. We find that the mutated lamin tail .domain is more compact and stable than the normal one. This altered structure and stability may enhance the association of intermediate filaments with the nuclear membrane, providing a molecular mechanism of the disease. We study the nuclear membrane association

  17. Impact of selected medical conditions on self-reported lower-extremity function in Mexican-American elderly.

    PubMed

    Ma, J; Markides, K S; Perkowski, L P; Stroup-Benham, C A; Lichtenstein, M; Goodwin, J S

    1998-01-01

    To examine the independent impact of common medical conditions on lower-extremity function in Mexican-American elderly. Cross-sectional study using a probability sample of non-institutionalized Mexican Americans aged 65 or older. The five Southwestern states, Texas, New Mexico, Arizona, Colorado and California. All subjects were interviewed in person (n = 2,873) or by proxy (n = 177) in their homes during late 1993 and early 1994. Respondents were asked whether they could perform four activities related to lower-extremity function without help: walking across a small room, getting from a bed to a chair, walking up and down stairs, and walking half a mile. A summary measure of lower body disability created from these four items was regressed on seven common medical conditions plus five control variables using multiple logistic regression. Adjusted Odds Ratios (OR) suggested that impaired lower-extremity function was associated with previous diagnosis of hip fracture (OR = 4.28), stroke (OR = 3.47), lower extremity arthritis (OR = 2.60), heart attack (OR = 2.29), diabetes (OR = 2.03) and obesity (OR = 1.50). Impaired lower-extremity function was significantly associated with older age (75+ years old), gender (female) and marital status (unmarried). In addition, there was a linear increase in the risk of function loss by number of medical conditions. It appears that Mexican-American elderly diagnosed with medical conditions, especially stroke and hip fracture, have a high risk for lower-extremity dysfunction. These findings have implications for efforts to prevent or reduce lower-extremity dysfunction, as well as for the provision of community-based long-term care services for Mexican-American elderly.

  18. Confidence intervals for expected moments algorithm flood quantile estimates

    USGS Publications Warehouse

    Cohn, T.A.; Lane, W.L.; Stedinger, J.R.

    2001-01-01

    Historical and paleoflood information can substantially improve flood frequency estimates if appropriate statistical procedures are properly applied. However, the Federal guidelines for flood frequency analysis, set forth in Bulletin 17B, rely on an inefficient "weighting" procedure that fails to take advantage of historical and paleoflood information. This has led researchers to propose several more efficient alternatives including the Expected Moments Algorithm (EMA), which is attractive because it retains Bulletin 17B's statistical structure (method of moments with the Log Pearson Type 3 distribution) and thus can be easily integrated into flood analyses employing the rest of the Bulletin 17B approach. The practical utility of EMA, however, has been limited because no closed-form method has been available for quantifying the uncertainty of EMA-based flood quantile estimates. This paper addresses that concern by providing analytical expressions for the asymptotic variance of EMA flood-quantile estimators and confidence intervals for flood quantile estimates. Monte Carlo simulations demonstrate the properties of such confidence intervals for sites where a 25- to 100-year streamgage record is augmented by 50 to 150 years of historical information. The experiments show that the confidence intervals, though not exact, should be acceptable for most purposes.

  19. A Combination of Extreme Environmental Conditions Favor the Prevalence of Endospore-Forming Firmicutes.

    PubMed

    Filippidou, Sevasti; Wunderlin, Tina; Junier, Thomas; Jeanneret, Nicole; Dorador, Cristina; Molina, Veronica; Johnson, David R; Junier, Pilar

    2016-01-01

    Environmental conditions unsuitable for microbial growth are the rule rather than the exception in most habitats. In response to this, microorganisms have developed various strategies to withstand environmental conditions that limit active growth. Endospore-forming Firmicutes (EFF) deploy a myriad of survival strategies in order to resist adverse conditions. Like many bacterial groups, they can form biofilms and detect nutrient scarcity through chemotaxis. Moreover, within this paraphyletic group of Firmicutes, ecophysiological optima are diverse. Nonetheless, a response to adversity that delimits this group is the formation of wet-heat resistant spores. These strategies are energetically demanding and therefore might affect the biological success of EFF. Therefore, we hypothesize that abundance and diversity of EFF should be maximized in those environments in which the benefits of these survival strategies offsets the energetic cost. In order to address this hypothesis, geothermal and mineral springs and drillings were selected because in these environments of steep physicochemical gradients, diversified survival strategies may become a successful strategy.We collected 71 samples from geothermal and mineral environments characterized by none (null), single or multiple limiting environmental factors (temperature, pH, UV radiation, and specific mineral composition). To measure success, we quantified EFF gene copy numbers (GCN; spo0A gene) in relation to total bacterial GCN (16S rRNA gene), as well as the contribution of EFF to community composition. The quantification showed that relative GCN for EFF reached up to 20% at sites characterized by multiple limiting environmental factors, whereas it corresponded to less than 1% at sites with one or no limiting environmental factor. Pyrosequencing of the 16S rRNA gene supports a higher contribution of EFF at sites with multiple limiting factors. Community composition suggested a combination of phylotypes for which active

  20. Cold-water coral growth under extreme environmental conditions, the Cape Lookout area, NW Atlantic

    NASA Astrophysics Data System (ADS)

    Mienis, F.; Duineveld, G. C. A.; Davies, A. J.; Lavaleye, M. M. S.; Ross, S. W.; Seim, H.; Bane, J.; van Haren, H.; Bergman, M. J. N.; de Haas, H.; Brooke, S.; van Weering, T. C. E.

    2014-05-01

    day, which is the largest temperature variability as measured so far in a cold-water coral habitat. Warm events, related to Gulf Stream meanders, had the duration of roughly 1 week and the current during these events was directed to the NNE. The consequences of such events must be significant given the strong effects of temperature on the metabolism of cold-water corals. Furthermore, elevated acoustic backscatter values and high mass fluxes were also recorded during these events, indicating a second stressor that may affect the corals. The abrasive nature of sand in combination with strong currents might sand blast the corals. We conclude that cold-water corals near Cape Lookout live under extreme conditions that limit mound growth at present.

  1. A Combination of Extreme Environmental Conditions Favor the Prevalence of Endospore-Forming Firmicutes

    PubMed Central

    Filippidou, Sevasti; Wunderlin, Tina; Junier, Thomas; Jeanneret, Nicole; Dorador, Cristina; Molina, Veronica; Johnson, David R.; Junier, Pilar

    2016-01-01

    Environmental conditions unsuitable for microbial growth are the rule rather than the exception in most habitats. In response to this, microorganisms have developed various strategies to withstand environmental conditions that limit active growth. Endospore-forming Firmicutes (EFF) deploy a myriad of survival strategies in order to resist adverse conditions. Like many bacterial groups, they can form biofilms and detect nutrient scarcity through chemotaxis. Moreover, within this paraphyletic group of Firmicutes, ecophysiological optima are diverse. Nonetheless, a response to adversity that delimits this group is the formation of wet-heat resistant spores. These strategies are energetically demanding and therefore might affect the biological success of EFF. Therefore, we hypothesize that abundance and diversity of EFF should be maximized in those environments in which the benefits of these survival strategies offsets the energetic cost. In order to address this hypothesis, geothermal and mineral springs and drillings were selected because in these environments of steep physicochemical gradients, diversified survival strategies may become a successful strategy.We collected 71 samples from geothermal and mineral environments characterized by none (null), single or multiple limiting environmental factors (temperature, pH, UV radiation, and specific mineral composition). To measure success, we quantified EFF gene copy numbers (GCN; spo0A gene) in relation to total bacterial GCN (16S rRNA gene), as well as the contribution of EFF to community composition. The quantification showed that relative GCN for EFF reached up to 20% at sites characterized by multiple limiting environmental factors, whereas it corresponded to less than 1% at sites with one or no limiting environmental factor. Pyrosequencing of the 16S rRNA gene supports a higher contribution of EFF at sites with multiple limiting factors. Community composition suggested a combination of phylotypes for which active

  2. Mixed hidden Markov quantile regression models for longitudinal data with possibly incomplete sequences.

    PubMed

    Marino, Maria Francesca; Tzavidis, Nikos; Alfò, Marco

    2016-01-01

    Quantile regression provides a detailed and robust picture of the distribution of a response variable, conditional on a set of observed covariates. Recently, it has be been extended to the analysis of longitudinal continuous outcomes using either time-constant or time-varying random parameters. However, in real-life data, we frequently observe both temporal shocks in the overall trend and individual-specific heterogeneity in model parameters. A benchmark dataset on HIV progression gives a clear example. Here, the evolution of the CD4 log counts exhibits both sudden temporal changes in the overall trend and heterogeneity in the effect of the time since seroconversion on the response dynamics. To accommodate such situations, we propose a quantile regression model, where time-varying and time-constant random coefficients are jointly considered. Since observed data may be incomplete due to early drop-out, we also extend the proposed model in a pattern mixture perspective. We assess the performance of the proposals via a large-scale simulation study and the analysis of the CD4 count data.

  3. Precisely Designed Isopeptide Bridge-Crosslinking Endows Artificial Hydrolases with High Stability and Catalytic Activity under Extreme Denaturing Conditions.

    PubMed

    Bai, Yu; Wang, Chao; Liang, Guodong; Lai, Wenqing; Xue, Huifang; Ling, Yanbo; Cheng, Maosheng; Liu, Keliang

    2017-07-25

    Enzymes normally lose their activities under extreme conditions due to the dissociation of their active tertiary structure. If an enzyme could maintain its catalytic activity under non-physiological or denaturing conditions, it might be used in more applications in the pharmaceutical and chemical industries. Recently, we reported a coiled-coil six-helical bundle (6HB) structure as a scaffold for designing artificial hydrolytic enzymes. Here, intermolecular isopeptide bonds were incorporated to enhance the stability and activity of such biomolecules under denaturing conditions. These isopeptide bridge-tethered 6HB enzymes showed exceptional stability against unfolding and retained or even had increased catalytic activity for a model hydrolysis reaction under thermal and chemical denaturing conditions. Thus, isopeptide bond-tethering represents an efficient route to construct ultrastable artificial hydrolases, with promising potential to maintain biocatalysis under extreme conditions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Flood quantile estimation at ungauged sites by Bayesian networks

    NASA Astrophysics Data System (ADS)

    Mediero, L.; Santillán, D.; Garrote, L.

    2012-04-01

    Estimating flood quantiles at a site for which no observed measurements are available is essential for water resources planning and management. Ungauged sites have no observations about the magnitude of floods, but some site and basin characteristics are known. The most common technique used is the multiple regression analysis, which relates physical and climatic basin characteristic to flood quantiles. Regression equations are fitted from flood frequency data and basin characteristics at gauged sites. Regression equations are a rigid technique that assumes linear relationships between variables and cannot take the measurement errors into account. In addition, the prediction intervals are estimated in a very simplistic way from the variance of the residuals in the estimated model. Bayesian networks are a probabilistic computational structure taken from the field of Artificial Intelligence, which have been widely and successfully applied to many scientific fields like medicine and informatics, but application to the field of hydrology is recent. Bayesian networks infer the joint probability distribution of several related variables from observations through nodes, which represent random variables, and links, which represent causal dependencies between them. A Bayesian network is more flexible than regression equations, as they capture non-linear relationships between variables. In addition, the probabilistic nature of Bayesian networks allows taking the different sources of estimation uncertainty into account, as they give a probability distribution as result. A homogeneous region in the Tagus Basin was selected as case study. A regression equation was fitted taking the basin area, the annual maximum 24-hour rainfall for a given recurrence interval and the mean height as explanatory variables. Flood quantiles at ungauged sites were estimated by Bayesian networks. Bayesian networks need to be learnt from a huge enough data set. As observational data are reduced, a

  5. Matter under extreme conditions experiments at the Linac Coherent Light Source

    DOE PAGES

    Glenzer, S. H.; Fletcher, L. B.; Galtier, E.; ...

    2015-12-10

    The Matter in Extreme Conditions end station at the Linac Coherent Light Source (LCLS) is a new tool enabling accurate pump-probe measurements for studying the physical properties of matter in the high-energy density physics regime. This instrument combines the world’s brightest x-ray source, the LCLS x-ray beam, with high-power lasers consisting of two nanosecond Nd:glass laser beams and one short-pulse Ti:sapphire laser. These lasers produce short-lived states of matter with high pressures, high temperatures or high densities with properties that are important for applications in nuclear fusion research, laboratory astrophysics and the development of intense radiation sources. In the firstmore » experiments, we have performed highly accurate x-ray diffraction and x-ray Thomson scattering techniques on shock-compressed matter resolving the transition from compressed solid matter to a co-existence regime and into the warm dense matter state. Furthermore, these complex charged-particle systems are dominated by strong correlations and quantum effects. They exist in planetary interiors and laboratory experiments, e.g., during high-power laser interactions with solids or the compression phase of inertial confinement fusion implosions. Applying record peak brightness X rays resolves the ionic interactions at atomic (Ångstrom) scale lengths and measure the static structure factor, which is a key quantity for determining equation of state data and important transport coefficients. Simultaneously, spectrally resolved measurements of plasmon features provide dynamic structure factor information that yield temperature and density with unprecedented precision at micron-scale resolution in dynamic compression experiments. This set of studies demonstrates our ability to measure fundamental thermodynamic properties that determine the state of matter in the high-energy density physics regime.« less

  6. Extremality Conditions and Regularity of Solutions to Optimal Partition Problems Involving Laplacian Eigenvalues

    NASA Astrophysics Data System (ADS)

    Ramos, Miguel; Tavares, Hugo; Terracini, Susanna

    2016-04-01

    Let {Ω subset {R}^N} be an open bounded domain and {m in {N}}. Given {k_1,ldots,k_m in {N}}, we consider a wide class of optimal partition problems involving Dirichlet eigenvalues of elliptic operators, of the following form inf{F({λ_{k1}}(ω_1),ldots,λ_{k_m}(ω_m)): (ω_1,ldots, ω_m) in {P}_m(Ω)}, where {λ_{k_i}(ω_i)} denotes the k i -th eigenvalue of {(-Δ,H10(ω_i))} counting multiplicities, and {{P}_m(Ω)} is the set of all open partitions of {Ω}, namely {P}_m(Ω)={(ω_1, ldots, ω_m):ω_i subset Ω open, ωi \\capω_j=emptyset forall i ≠ j }. While the existence of a quasi-open optimal partition {(ω_1,ldots, ω_m)} follows from a general result by Bucur, Buttazzo and Henrot [Adv Math Sci Appl 8(2):571-579, 1998], the aim of this paper is to associate with such minimal partitions and their eigenfunctions some suitable extremality conditions and to exploit them, proving as well the Lipschitz continuity of some eigenfunctions, and the regularity of the partition in the sense that the free boundary {\\cup_{i=1}^m partial ωi \\cap Ω} is, up to a residual set, locally a {C^{1,α}} hypersurface. This last result extends the ones in the paper by Caffarelli and Lin [J Sci Comput 31(1-2):5-18, 2007] to the case of higher eigenvalues.

  7. Complex layered dental restorations: Are they recognizable and do they survive extreme conditions?

    PubMed

    Soon, Alistair S; Bush, Mary A; Bush, Peter J

    2015-09-01

    Recent research has shown that restorative dental materials can be recognized by microscopy and elemental analysis (scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray fluorescence; SEM/EDS and XRF) and that this is possible even in extreme conditions, such as cremation. These analytical methods and databases of dental materials properties have proven useful in DVI (disaster victim identification) of a commercial plane crash in 2009, and in a number of other victim identification cases. Dental materials appear on the market with ever expanding frequency. With their advent, newer methods of restoration have been proposed and adopted in the dental office. Methods might include placing multiple layers of dental materials, where they have different properties including adhesion, viscosity, or working time. These different dental materials include filled adhesives, flowable resins, glass ionomer cements, composite resins, liners and sealants. With possible combinations of different materials in these restorations, the forensic odontologist is now confronted with a new difficulty; how to recognize each individual material. The question might be posed if it is even possible to perform this task. Furthermore, an odontologist might be called upon to identify a victim under difficult circumstances, such as when presented with fragmented or incinerated remains. In these circumstances the ability to identify specific dental materials could assist in the identification of the deceased. Key to use of this information is whether these new materials and methods are detailed in the dental chart. Visual or radiographic inspection may not reveal the presence of a restoration, let alone the possible complex nature of that restoration. This study demonstrates another scientific method in forensic dental identification. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. "Rotten Ice": Characterizing the Physical Properties of Arctic Sea Ice Under Conditions of Extreme Summer Melt

    NASA Astrophysics Data System (ADS)

    Light, B.; Frantz, C. M.; Junge, K.; Orellana, M. V.; Carpenter, S.; Farley, S. M.; Lieb-Lappen, R.; Courville, Z.

    2016-12-01

    The microstructural properties of sea ice are central to understanding the mechanical, thermal, electrical, and optical properties of a sea ice cover. Over the course of an annual cycle, this small scale structure routinely evolves from a network of mostly isolated brine and gas inclusions prevalent in cold ice, to a more connected, more permeable structure as the ice endures summer melt processes. In the case of extreme summer melt, sea ice can become "rotten", and it is expected that such rotten ice may become more prevalent as melt seasons lengthen. Rotten ice is approximately isothermal, largely drained of brine, and is typified by the presence of large multi-cm-scale void spaces that contribute to its high permeability and low structural integrity. These properties are expected to alter the ice cover response to dynamic forcing, ability to backscatter incident light, and its melt rate. An interdisciplinary effort to characterize the physical properties of rotten first-year ice, in concert with some of its chemical and biological properties, is being carried out both in the field and in the laboratory. Time-series samples focusing on the evolution of ice microstructure were acquired and analyzed for shore-fast first-year sea ice near Barrow, Alaska in May - July of 2015. Laboratory studies have focused on assessing the seasonal evolution of optical properties of this ice, as well as the measurement of melt rates of ice grown under carefully controlled laboratory conditions. Preliminary results from these studies illuminate some of the physical and biophysical controls on late summer ice melt.

  9. PREFACE: International Symposium on Molecular Conductors: Novel Functions of Molecular Conductors under Extreme Conditions (ISMC 2008)

    NASA Astrophysics Data System (ADS)

    Takahashi, Toshihiro; Suzumura, Yoshikazu

    2008-02-01

    The International Symposium on Molecular Conductors 2008 (ISMC2008) was held as the second international symposium of the project entitled `Novel Functions of Molecular Conductors under Extreme Conditions', which was supported by the Grant-in-aid for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science and Technology in Japan. The project lasted from September 2003 to March 2008, and was completed by this symposium held at Okazaki Conference Center, Institute for Molecular Science, Okazaki, Japan (23-25 July 2008), which about 100 scientists attended. During the symposium, five project teams gave summary talks and exciting talks were given on the topics developed recently not only by the members of the project but also by other scientists including invited speakers from abroad, who are doing active research on molecular conductors. It is expected that papers presented in the symposium will give valuable hints for the next step in the research of this field. Therefore the organizers of this symposium decided to publish this proceedings in order to demonstrate these activities, not only for the local community of the project, but also for the broad society of international scientists who are interested in molecular conductors. The editors, who are also the organizers of this symposium, believe that this proceedings provides a significant and relevant contribution to the field of molecular conductors since it is the first time we have published such a proceedings as an electronic journal. We note that all papers published in this volume of Journal of Physics: Conference Series have been peer reviewed by expert referees. Editors made every effort to satisfy the criterion of a proceedings journal published by IOP Publishing. Toshihiro Takahashi and Yoshikazu Suzumura Editors: Toshihiro Takahashi (Gakushuin University) (Chairman) Kazushi Kanoda (University of Tokyo) Seiichi Kagoshima (University of Tokyo) Takehiko Mori (Tokyo

  10. An Invariant-Preserving ALE Method for Solids under Extreme Conditions

    SciTech Connect

    Sambasivan, Shiv Kumar; Christon, Mark A

    2012-07-17

    We are proposing a fundamentally new approach to ALE methods for solids undergoing large deformation due to extreme loading conditions. Our approach is based on a physically-motivated and mathematically rigorous construction of the underlying Lagrangian method, vector/tensor reconstruction, remapping, and interface reconstruction. It is transformational because it deviates dramatically from traditionally accepted ALE methods and provides the following set of unique attributes: (1) a three-dimensional, finite volume, cell-centered ALE framework with advanced hypo-/hyper-elasto-plastic constitutive theories for solids; (2) a new physically and mathematically consistent reconstruction method for vector/tensor fields; (3) advanced invariant-preserving remapping algorithm for vector/tensor quantities; (4) moment-of-fluid (MoF) interface reconstruction technique for multi-material problems with solids undergoing large deformations. This work brings together many new concepts, that in combination with emergent cell-centered Lagrangian hydrodynamics methods will produce a cutting-edge ALE capability and define a new state-of-the-art. Many ideas in this work are new, completely unexplored, and hence high risk. The proposed research and the resulting algorithms will be of immediate use in Eulerian, Lagrangian and ALE codes under the ASC program at the lab. In addition, the research on invariant preserving reconstruction/remap of tensor quantities is of direct interest to ongoing CASL and climate modeling efforts at LANL. The application space impacted by this work includes Inertial Confinement Fusion (ICF), Z-pinch, munition-target interactions, geological impact dynamics, shock processing of powders and shaped charges. The ALE framework will also provide a suitable test-bed for rapid development and assessment of hypo-/hyper-elasto-plastic constitutive theories. Today, there are no invariant-preserving ALE algorithms for treating solids with large deformations. Therefore

  11. Matter under extreme conditions experiments at the Linac Coherent Light Source

    NASA Astrophysics Data System (ADS)

    Glenzer, S. H.; Fletcher, L. B.; Galtier, E.; Nagler, B.; Alonso-Mori, R.; Barbrel, B.; Brown, S. B.; Chapman, D. A.; Chen, Z.; Curry, C. B.; Fiuza, F.; Gamboa, E.; Gauthier, M.; Gericke, D. O.; Gleason, A.; Goede, S.; Granados, E.; Heimann, P.; Kim, J.; Kraus, D.; MacDonald, M. J.; Mackinnon, A. J.; Mishra, R.; Ravasio, A.; Roedel, C.; Sperling, P.; Schumaker, W.; Tsui, Y. Y.; Vorberger, J.; Zastrau, U.; Fry, A.; White, W. E.; Hasting, J. B.; Lee, H. J.

    2016-05-01

    The matter in extreme conditions end station at the Linac Coherent Light Source (LCLS) is a new tool enabling accurate pump-probe measurements for studying the physical properties of matter in the high-energy density (HED) physics regime. This instrument combines the world’s brightest x-ray source, the LCLS x-ray beam, with high-power lasers consisting of two nanosecond Nd:glass laser beams and one short-pulse Ti:sapphire laser. These lasers produce short-lived states of matter with high pressures, high temperatures or high densities with properties that are important for applications in nuclear fusion research, laboratory astrophysics and the development of intense radiation sources. In the first experiments, we have performed highly accurate x-ray diffraction and x-ray Thomson scattering measurements on shock-compressed matter resolving the transition from compressed solid matter to a co-existence regime and into the warm dense matter state. These complex charged-particle systems are dominated by strong correlations and quantum effects. They exist in planetary interiors and laboratory experiments, e.g., during high-power laser interactions with solids or the compression phase of inertial confinement fusion implosions. Applying record peak brightness x-rays resolves the ionic interactions at atomic (Ångstrom) scale lengths and measure the static structure factor, which is a key quantity for determining equation of state data and important transport coefficients. Simultaneously, spectrally resolved measurements of plasmon features provide dynamic structure factor information that yield temperature and density with unprecedented precision at micron-scale resolution in dynamic compression experiments. These studies have demonstrated our ability to measure fundamental thermodynamic properties that determine the state of matter in the HED physics regime.

  12. Recent trends in heavy precipitation extremes over Germany: A thorough intercomparison between different statistical approaches

    NASA Astrophysics Data System (ADS)

    Donner, Reik; Passow, Christian

    2016-04-01

    comparison with GEV and GP-based approaches, quantile regression approaches thus allow for more flexibility and make full use of all available observational values, no matter if extreme or not. Due to the latter fact, trends in extreme values can be more easily assessed based on shorter time series. However, the question under which conditions and to what extent regression and extreme value theory-based approaches provide consistent results has not yet been fully explored. In this study, we provide a thorough inter-comparison between the recent trends in extreme precipitation events (assessed in terms of daily precipitation sums) from a large set of German weather stations as revealed by the classical (monthly) block maxima method with linearly time-dependent GEV parameters and linear quantile regression of the full time series. For the study period from 1951 to 2006, our main findings are as follows: (1) The spatial patterns of quantile trends for various high (>90%) percentiles and trends in the location parameter of the GEV distribution are qualitatively consistent and exhibit significant correlations, which, however, clearly deviate from an ideal correspondence. (2) In comparison with the trend parameters, the intercepts of the respective linear models for the GEV location parameter and different quantiles exhibit considerably larger mutual correlation values. (3) Quantile regression indicates more stations with strongly positive trends in extreme precipitation than the block maxima method. Moreover, the significance statements provided by the GEV statistics are more conservative than those resulting from quantile regression. Significant upward trends are generally restricted to Southern and Western Germany and are almost completely absent in the Northeastern part of the country. (4) More complex GEV models including linear trends in both location and dispersion parameter need to be considered only for a small subset of all stations (202 out of 2342). In most cases

  13. In situ insights to Se (S) partitioning between silicate and metallic melts at extreme conditions

    NASA Astrophysics Data System (ADS)

    Borchert, M.; Petitgirard, S.; Appel, K.; Watenphul, A.; Morgenroth, W.

    2012-12-01

    The Earth's core mainly consists of a metallic Fe-Ni mixture. However, seismic observations show that the density is about 5-10% lower than expected for an Fe-Ni alloy under similar pressure and temperature conditions (e.g., [1,2]). This discovery initiated numerous studies to identify and quantify light elements in the Earth0s core. Among others, sulphur has been suggested to be a promisingly candidate to alloy with the metallic core because of its depletion in the crust and the mantle relative to other volatile elements by several orders of magnitude (e.g., [3-5]). In the last decades, several experimental studies have aimed to quantify the sulphur content in the Earth's core and to determine its influence on the physical properties (e.g., [6]). However, experimental data on sulphur partitioning between silicate and metallic liquids at pressures and temperatures relevant for core-mantle boundary conditions are missing. This lack is due to pressure and temperature limitations of conventional experimental approaches (up to 25 GPa and 2200 K). New developments, like laser-heated diamond-anvil cells (LDAC), allow studies at core-mantle boundary conditions, but in-situ chemical analysis of sulphur in LDACs is impossible due to the high absorption of S fluorescence in the diamonds. Instead of sulphur, selenium can be used to model sulphur partitioning between silicate and metallic melts at elevated PT conditions. This is based on the fact that sulphur and selenium can be considered as geochemical twins ([7,8]). The main advantage of this approach is the much higher excitation energy of selenium compared to sulphur, which enables in-situ XRF analysis in LDACs. Here, we present preliminary data on Se partitioning between silicate and metallic melt at extreme conditions. The experiments have been performed in double-sided laser-heated LDACs at the high pressure beamlines P02.2 (DESY, Germany) and ID27 (ESRF, France) as described in [9]. Micro-XRF mappings are used to

  14. Optical properties of CO2 under extreme conditions: measured and simulated data

    NASA Astrophysics Data System (ADS)

    Stefani, Stefania; Piccioni, Giuseppe; Snels, Marcel; Rodin, Alexander V.; Ignatiev, Nikolay; Adriani, Alberto

    The modelling of the transmittance of gases at extreme conditions, in particular at high pres-sure and high temperature, in some cases is not as accurate as it would need for an accurate determination of the physical-chemical parameters in deep atmospheres. To better interpret the data coming from space borne remote sensing instruments, in particular those flying at Venus Express spacecraft, we have built a laboratory set-up to measure the optical properties of gases at high pressures and/or temperatures. A Fourier transform infrared (FT-IR) interferometer has been integrated with a special customized high pressure -high temperature (HP-HT) gas cell. The system has been employed to measure CO2 transmittance under conditions typically found in the deep atmosphere of Venus. This set-up is able to operate in a wide spectral range, from 350 to 25000 cm-1 (0.4 to 29 m ), with a relatively high spectral resolution, from 10 to 0.07 cm-1. The HP-HT gas cell is adapted to pressures up to about 50 bar (real limitation being the CO2 source) and a temperature up to 350C. Measurements were done varying the pressure ranging from 1 to 50 bar and the temperature from 298 to 550K. Measurements have been compared with synthetic spectra obtained using two different models: one implementing a line by line calculation and another, which takes into account the line mixing effect in the strong collision approximation. A preliminary comparison leads us to conclude that in the real gases under pressure higher than only a few bars, the shape of the spectral lines no longer follows the conventional Voigt form. In particular, the absorption in the far wings of strong ro-vibrational bands at a few hundred cm-1 from band cores, is 103-104 times weaker than predicted by the Lorentz profile, which also results in stronger absorption near the band cores. A remarkable agreement between measurements and synthetic spectra based on the strong col-lision approximation provides a strong argument in

  15. Cold-water coral growth under extreme environmental conditions, the Cape Lookout area, NW Atlantic

    NASA Astrophysics Data System (ADS)

    Mienis, F.; Duineveld, G.; Davies, A. J.; Lavaleye, M. J. N.; Ross, S. W.; Seim, H.; Bane, J.; van Haren, H.; Bergman, M.; de Haas, H.; Brooke, S.; van Weering, T.

    2013-12-01

    far in a cold-water coral habitat. Warm events, related to Gulf Stream meanders, had the duration of roughly one week and the current during these events was directed to the NNE. The consequences of such events must be significant given the strong effects of temperature on the metabolism of cold-water corals. Furthermore, elevated acoustic backscatter values and high mass fluxes were also recorded during these events, indicating a second stressor that may affect the corals. The abrasive nature of sand in combination with strong currents might sand blast the corals. We conclude that cold-water corals near Cape Lookout live under extreme conditions that limit mound growth at present.

  16. Reactivity of Xe with ice at extreme P-T conditions

    NASA Astrophysics Data System (ADS)

    Sanloup, C.; Hochlaf, M.; Maynard-Casely, H.; Gregoryanz, E.; Mezouar, M.

    2010-12-01

    Water is an important component of terrestrial and giant planets so that any reactivity with Xe at depth would have strong consequences on our knowledge of planetary dynamics as it heavily relies on Xe isotopes geochemistry. The chemistry of ‘noble gas’ have seen fascinating experimental and theoretical advances during the last twenty years as highlighted by review papers (1,2). Noble gas chemistry proceeds essentially by photosynthesis of precursors in a low-temperature noble-gas matrix. The pressure variable has seldom been investigated as a mean to enforce Xe to bond other elements (3). Xe is among the gases that stabilize clathrate hydrates through van der Waals interactions. Xe hydrates are stable up to 2.5 GPa, before dissociating into Xe plus ice VII (4). However, the chemistry of water with solid Xe has been successfully explored by UV photolysis (5,6). Those findings plus our own results on the stability of Xe oxides in the terrestrial crust (7) let us envisage that the chemistry of Xe with oxygen at extreme conditions could be flourishing. We have thus explored the reactivity of Xe with water up to 80 GPa by using a laser-heated diamond-anvil cell combined with in situ x-ray diffraction measurements. Formation of a compound is indeed observed at conditions that could occur in the interiors of ice-rich giant planets Uranus and Neptune. To complement the x-ray diffraction data, ab initio calculations have been carried out to determine the molecular structure of the new found compound. These resuts hence add another example of noble gas sequestration in giant planets, as recently proposed for Ne (8). References: 1. W. Grochala, Chem. Soc. Rev. 1632, 36 (2007). 2. R. B. Gerber, Annu. Rev. Phys. Chem., 55, 55 (2004). 3. A. I. Katz and V. A. Apkarian, J. Phys. Chem., 94, 6671-6678 (1990). 4. C. Sanloup et al., PNAS 99, 25 (2002). 5. M. Pettersson et al., Eur. J. Inorg. Chem. 505, 729 (1999). 6. L. Khriachtchev et al., JACS 130, 6114 (2008). 7. C. Sanloup et

  17. Analytical solutions for determining extreme water levels in surge tank of hydropower station under combined operating conditions

    NASA Astrophysics Data System (ADS)

    Wang, Bingbao; Guo, Wencheng; Yang, Jiandong

    2017-06-01

    Combined operating condition usually refers to the control operating condition under which the highest and lowest water levels occur in a surge tank of hydropower station. In this paper, with the basic equations of surge analysis and nonlinear vibrational asymptotic method, analytical expressions of the worst superimposition time of surge waves in an upstream surge tank under four typical combined operating conditions (i.e. load-acceptance-then-rejection, successive load rejection, successive load acceptance and load-rejection-then-acceptance) are derived firstly. Then using these expressions, the analytical extreme water levels are determined. The analytical solutions are verified with numerical simulation results. Finally, the effect of the hydraulic resistance coefficient of surge tank on the control operating condition is investigated. The results indicate that: The analytical solutions for determining extreme water levels in surge tank under various combined operating conditions are accurate due to the good agreements between the analytical results and the numerical results. With the increase of the hydraulic resistance coefficient of surge tank, the control operating condition for the highest water level shifts from load-acceptance-then-rejection condition to successive load rejection condition, and the control operating condition for the lowest water level shifts from load-rejection-then-acceptance condition to successive load acceptance condition.

  18. Extreme conditioning programs and injury risk in a US Army Brigade Combat Team.

    PubMed

    Grier, Tyson; Canham-Chervak, Michelle; McNulty, Vancil; Jones, Bruce H

    2013-01-01

    Brigades and battalions throughout the US Army are currently implementing a variety of exercise and conditioning programs with greater focus on preparation for mission-specific tasks. An Army physical therapy clinic working with a light infantry brigade developed the Advanced Tactical Athlete Conditioning (ATAC) program. The ATAC program is a unique physical training program consisting of high-intensity aquatic exercises, tactical agility circuits, combat core conditioning, and interval speed training. Along with ATAC, battalions have also incorporated components of fitness programs such as the Ranger Athlete Warrior program and CrossFit (Crossfit, Inc, Santa Monica, CA) an extreme conditioning program (ECP). To determine if these new programs (ATAC, ECP) had an effect on injury rates and physical fitness. Surveys were administered to collect personal characteristics, tobacco use, personal physical fitness training, Army physical fitness test results, and self-reported injuries. Medical record injury data were obtained 6 months before and 6 months after the implementation of the new program. Predictors of injury risk were assessed using multivariate logistic regression. Odds ratios (OR) and 95% confidence intervals (CI) were reported. Injury incidence among Soldiers increased 12% for overall injuries and 16% for overuse injuries after the implementation of the ATAC/ECPs. However, injury incidence among Soldiers not participating in ATAC/ECPs also increased 14% for overall injuries and 10% for overuse injuries. Risk factors associated with higher injury risk for Soldiers participating in ATAC/ECPs included: greater mileage run per week during unit physical training (OR (>16 miles per week÷≤7 miles per week)=2.24, 95% CI, 1.33-3.80); higher body mass index (BMI) (OR (BMI 25-29.9÷BMI<25)=1.77, 95% CI, 1.29-2.44), (OR (BMI =30÷BMI<25)=2.72, 95% CI, 1.67-4.43); cigarette use (OR (smoker÷nonsmoker)=1.80, 95% CI, 1.34-2.42); poor performance on the 2-mile run during

  19. Parametric modeling of quantile regression coefficient functions with censored and truncated data.

    PubMed

    Frumento, Paolo; Bottai, Matteo

    2017-02-09

    Quantile regression coefficient functions describe how the coefficients of a quantile regression model depend on the order of the quantile. A method for parametric modeling of quantile regression coefficient functions was discussed in a recent article. The aim of the present work is to extend the existing framework to censored and truncated data. We propose an estimator and derive its asymptotic properties. We discuss goodness-of-fit measures, present simulation results, and analyze the data that motivated this article. The described estimator has been implemented in the R package qrcm.

  20. Effectiveness Analysis of Filters Used with Radon Detectors under Extreme Environmental Conditions for Long-term Exposures

    NASA Astrophysics Data System (ADS)

    Moreno, V.; Font, Ll.; Baixeras, C.; Garcia-Orellana, J.; Bach, J.; Grossi, C.; Vargas, A.

    Active and passive radon detectors have been exposed with different filter configurations at the INTE radon chamber controlled conditions. Correction factors and delay times of the radon diffusion through each filter have been determined. Additionally, some of the studied filter/detector configurations have been used to measure radon in several workplaces and outdoor sites under real extreme environmental conditions. Analysis of these detectors showed partial degradation, so used filters seem not to be protective enough for long-term exposures.

  1. Quantitative Proteomic Analysis of Germination of Nosema bombycis Spores under Extremely Alkaline Conditions

    PubMed Central

    Liu, Han; Chen, Bosheng; Hu, Sirui; Liang, Xili; Lu, Xingmeng; Shao, Yongqi

    2016-01-01

    The microsporidian Nosema bombycis is an obligate intracellular pathogen of the silkworm Bombyx mori, causing the epidemic disease Pebrine and extensive economic losses in sericulture. Although N. bombycis forms spores with rigid spore walls that protect against various environmental pressures, ingested spores germinate immediately under the extremely alkaline host gut condition (Lepidoptera gut pH > 10.5), which is a key developmental turning point from dormant state to infected state. However, to date this process remains poorly understood due to the complexity of the animal digestive tract and the lack of genetic tools for microsporidia. Here we show, using an in vitro spore germination model, how the proteome of N. bombycis changes during germination, analyse specific metabolic pathways employed in detail, and validate key functional proteins in vivo in silkworms. By a label-free quantitative proteomics approach that is directly based on high-resolution mass spectrometry (MS) data, a total of 1136 proteins were identified with high confidence, with 127 proteins being significantly changed in comparison to non-germinated spores. Among them, structural proteins including polar tube protein 1 and 3 and spore wall protein (SWP) 4 and 30 were found to be significantly down-regulated, but SWP9 significantly up-regulated. Some nucleases like polynucleotide kinase/phosphatase and flap endonucleases 1, together with a panel of hydrolases involved in protein degradation and RNA cleavage were overrepresented too upon germination, which implied that they might play important roles during spore germination. The differentially regulated trends of these genes were validated, respectively, by quantitative RT-PCR and 3 proteins of interest were confirmed by Western blotting analyses in vitro and in vivo. Furthermore, the pathway analysis showed that abundant up- and down-regulations appear involved in the glycolysis, pentose phosphate pathway, purine, and pyrimidine metabolism

  2. Quantitative Proteomic Analysis of Germination of Nosema bombycis Spores under Extremely Alkaline Conditions.

    PubMed

    Liu, Han; Chen, Bosheng; Hu, Sirui; Liang, Xili; Lu, Xingmeng; Shao, Yongqi

    2016-01-01

    The microsporidian Nosema bombycis is an obligate intracellular pathogen of the silkworm Bombyx mori, causing the epidemic disease Pebrine and extensive economic losses in sericulture. Although N. bombycis forms spores with rigid spore walls that protect against various environmental pressures, ingested spores germinate immediately under the extremely alkaline host gut condition (Lepidoptera gut pH > 10.5), which is a key developmental turning point from dormant state to infected state. However, to date this process remains poorly understood due to the complexity of the animal digestive tract and the lack of genetic tools for microsporidia. Here we show, using an in vitro spore germination model, how the proteome of N. bombycis changes during germination, analyse specific metabolic pathways employed in detail, and validate key functional proteins in vivo in silkworms. By a label-free quantitative proteomics approach that is directly based on high-resolution mass spectrometry (MS) data, a total of 1136 proteins were identified with high confidence, with 127 proteins being significantly changed in comparison to non-germinated spores. Among them, structural proteins including polar tube protein 1 and 3 and spore wall protein (SWP) 4 and 30 were found to be significantly down-regulated, but SWP9 significantly up-regulated. Some nucleases like polynucleotide kinase/phosphatase and flap endonucleases 1, together with a panel of hydrolases involved in protein degradation and RNA cleavage were overrepresented too upon germination, which implied that they might play important roles during spore germination. The differentially regulated trends of these genes were validated, respectively, by quantitative RT-PCR and 3 proteins of interest were confirmed by Western blotting analyses in vitro and in vivo. Furthermore, the pathway analysis showed that abundant up- and down-regulations appear involved in the glycolysis, pentose phosphate pathway, purine, and pyrimidine metabolism

  3. Materials response under extreme conditions: a path to materials science above 1000 GPa

    NASA Astrophysics Data System (ADS)

    Remington, Bruce

    2005-07-01

    Solid state experiments at extreme pressures (10-100 GPa) and strain rates (1.e6 -- 1.e8 1/s) are being developed on high-energy laser facilities. [1] A quasi-isentropic, ramped-pressure (shockless) drive is being developed on the Omega laser. [2] Constitutive models for solid-state strength under these conditions are tested with experiments measuring perturbation growth due to the Rayleigh-Taylor instability in solid-state samples. [3] Lattice compression, phase, and temperature are deduced from extended x-ray absorption fine structure (EXAFS) measurements, from which the shock-induced alpha-omega phase transition in Ti is inferred to occur on sub-nanosec time scales. [4] Time resolved lattice response and phase can be inferred from dynamic x-ray diffraction measurements, where the elastic-plastic (1D-3D) lattice relaxation in shocked Cu is shown to occur promptly (sub-nsec). [5] Large-scale MD simulations have elucidated the microscopic dynamics that underlie the 3D lattice relaxation. [6] Deformation mechanisms, such as the slip-twinning transition in shocked single-crystal Cu, are identified by examining the residual microstructure in recovered samples. [7] Designs will be shown for reaching much higher pressures, (greater than 1000 GPa), in the solid state on the NIF laser. [8] *This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48. [1] B.A. Remington et al., Met. Mat. Trans. 35A, 2587 (2004). [2] J. Edwards et al., PRL 92, 075002 (2004). [3] K.T. Lorenz et al., PoP, in press (May, 2005). [4] B. Yaakobi et al., PRL 92, 095504 (2004). [5] A. Loveridge-Smith et al., PRL 86, 2349 (2001). [6] E.M. Bringa et al., Nature, submitted (March, 2005). [7] M.S. Schneider et al., Met. Mat. Trans. 35A, 2633 (2004). [8] B.A. Remington et al., in press, ApSS 298 (July, 2005).

  4. Identifying the Drivers and Occurrence of Historical and Future Extreme Air-quality Events in the United States Using Advanced Statistical Techniques

    NASA Astrophysics Data System (ADS)

    Porter, W. C.; Heald, C. L.; Cooley, D. S.; Russell, B. T.

    2013-12-01

    Episodes of air-quality extremes are known to be heavily influenced by meteorological conditions, but traditional statistical analysis techniques focused on means and standard deviations may not capture important relationships at the tails of these two respective distributions. Using quantile regression (QR) and extreme value theory (EVT), methodologies specifically developed to examine the behavior of heavy-tailed phenomena, we analyze extremes in the multi-decadal record of ozone (O3) and fine particulate matter (PM2.5) in the United States. We investigate observations from the Air Quality System (AQS) and Interagency Monitoring of Protected Visual Environments (IMPROVE) networks for connections to meteorological drivers, as provided by the National Center for Environmental Prediction (NCEP) North American Regional Reanalysis (NARR) product. Through regional characterization by quantile behavior and EVT modeling of the meteorological covariates most responsible for extreme levels of O3 and PM2.5, we estimate pollutant exceedance frequencies and uncertainties in the United States under current and projected future climates, highlighting those meteorological covariates and interactions whose influence on air-quality extremes differs most significantly from the behavior of the bulk of the distribution. As current policy may be influenced by air-quality projections, we then compare these estimated frequencies to those produced by NCAR's Community Earth System Model (CESM) identifying regions, covariates, and species whose extreme behavior may not be adequately captured by current models.

  5. Evaluation of Spatio-temporal Drought using Water Resource Quantile Map

    NASA Astrophysics Data System (ADS)

    Moon, Soojin; Suh, Aesook; Kang, Boosik

    2016-04-01

    Among those various natural disasters, the drought which is contrasted to the flood is not defined in only one case and it is true that the standard to estimate and conclude the drought is in vague with the long-term water insufficiency following the local and time-periodic rainfall disparity. Drought indices is mainly used as an index for evaluating drought. However, it is not an absolute indicator that can evaluate drought. Depending on the characteristics of each index in a variety of conditions such as local and environment, after grasping a better applicability in the use surfaces to suit the purpose of the user, using the appropriate index to be drought evaluation shall. After considering the various characteristics such as regional and environment with each index, the drought index have to use appropriately. Accordingly, there has been a lot of research for drought monitoring. However, objective method that can be evaluated experts as well as the general people on the actual drought situation, is deficient. In this study, it suggested RSQM (Real-time Storage Quantile Map) and RRQM (Real-time Riverflow Quantile Map) in the way to calculating the quantile of the current value corresponding to the usual value of the annual value river water level and storage rate of multi-purpose dam. It was calculated the probability distribution by selecting a typical water level stations and multipurpose dam of each basin. And the RSQM and RRQM were comparison and analysis to SPI and PDSI Index. These schemes can be objectively judged insufficient degree and drought conditions in water in real time. The RSQM and RSQM are meaning the supply potential of water resources and stress value of river environment. RRQM is mainly due to represent the adjusted value of downstream of multi-purpose dam. Accordingly it does not show the tendency of the representation of the drought to match exactly. However, RRQM is more directly represented about visually showing drought conditions

  6. (When and where) Do extreme climate events trigger extreme ecosystem responses? - Development and initial results of a holistic analysis framework

    NASA Astrophysics Data System (ADS)

    Hauber, Eva K.; Donner, Reik V.

    2015-04-01

    In the context of ongoing climate change, extremes are likely to increase in magnitude and frequency. One of the most important consequences of these changes is that the associated ecological risks and impacts are potentially rising as well. In order to better anticipate and understand these impacts, it therefore becomes more and more crucial to understand the general connection between climate extremes and the response and functionality of ecosystems. Among other region of the world, Europe presents an excellent test case for studies concerning the interaction between climate and biosphere, since it lies in the transition region between cold polar and warm tropical air masses and thus covers a great variety of different climatic zones and associated terrestrial ecosystems. The large temperature differences across the continent make this region particularly interesting for investigating the effects of climate change on biosphere-climate interactions. However, previously used methods for defining an extreme event typically disregard the necessity of taking seasonality as well as seasonal variance appropriately into account. Furthermore, most studies have focused on the impacts of individual extreme events instead of considering a whole inventory of extremes with their respective spatio-temporal extents. In order to overcome the aforementioned research gaps, this work introduces a new approach to studying climate-biosphere interactions associated with extreme events, which comprises three consecutive steps: (1) Since Europe exhibits climatic conditions characterized by marked seasonality, a novel method is developed to define extreme events taking into account the seasonality in all quantiles of the probability distribution of the respective variable of interest. This is achieved by considering kernel density estimates individually for each observation date during the year, including the properly weighted information from adjacent dates. By this procedure, we obtain

  7. The effect of visual field condition on kinetic in upper extremities and e.m.g in lower extremities while performing reaching in normal adults

    PubMed Central

    Park, Hyekang; Kang, Youngeun; Yoo, Minah; Lee, Bomjin; Yang, Jeongok; Lee, Joongsook; Han, Dongwook; Oh, Taeyoung

    2017-01-01

    [Purpose] The aims of this study was to investigate mean velocity and angle of shoulder joint, activation of tibialis anterior and gastrocnemius according to both eyes, dominant eye and non-dominant eye condition during reaching task in normal adults. [Subjects and Methods] Our research recruited 24 participants (male 11, female 13) in Silla University. Participants were performed reaching out movement by conditions of both eye, dominants eye, non-dominants eye. The target was placed at 45 degree diagonal direction and distance far away 130% of their arm length. Kinetic analysis of the upper extremities was investigated by QUALISYS 3-dimensional motion analysis system. Muscle activation were measured by EMG during reaching tasks. The collected data were statistically processed using the SPSS for win version 20.0. [Results] There was a significant difference of shoulder joint velocity of flexion, abduction and internal rotation according to visual field condition during reaching tasks. There was no significant difference of shoulder joint angle and muscle activation according to visual field conditions during reaching tasks. [Conclusion] In conclusion, visual field has an influence on shoulder joint velocity. Therefore, the visual field may be to play an important role in reach performance. PMID:28210047

  8. Investigating the Effects of Simulated Space conditions on Novel Extremely Halophilic Archaea: Halovarius Luteus gen. nov., sp. nov.

    NASA Astrophysics Data System (ADS)

    Feshangsaz, Niloofar; Van Loon, ing.. Jack J. W. A.; Nazmi, Kamran; Semsarha, Farid

    2016-07-01

    Studying halophiles from different environments of Earth provide new insights into our search for life in the universe. Haloarchaea show some unique characteristics and physiological adaptations like acidic proteins against harsh environments such as natural brine with salt concentration approaching saturation (5 M) and regions with low active water. These properties make haloarchaea interesting candidate for astrobiological studies. Halovarius luteus gen. nov., sp. nov. a novel extremely halophilic archaeon from Urmia salt lake, in Iran has been chosen to explore its resistance against a series of extreme conditions. The aim of this study is to assess the resistance of strain DA50T under the effects of simulated space conditions like simulated microgravity, hypergravity, and desiccation. In this paper we will discuss the results of these studies where we specifically focus on changes in carotenoid pigments production and whole cell proteome. This is the first report of very novel Iranian archaea in response to extreme space conditions. The pigments were extracted by acetone and methanol. Pigments were analyzed by scanning the absorbance spectrum in the UV-VIS spectrophotometer. And they were separated by TLC. Whole protein from cell lysate supernatant was extracted after lysis with Bacterial Protein Extraction Reagent and fractionated by RP-HPLC using C18 column. Proteome analyzed by electrophoresis (SDS-PAGE), and MALDI-TOF. Carotenoid pigments are formed under different extreme conditions such as dry environment and gravitational changes. Also the protein composition exhibits alterations after exposure to the same conditions. Our conclusion is that pigments and proteins formation depend on the growth circumstances. Halophiles use this as an adaptation to survive under different environmental conditions.

  9. Drop-box Weir for Measuring Flow Rates Under Extreme Flow Conditions

    USDA-ARS?s Scientific Manuscript database

    Sediment and large rocks often are transported in runoff during extreme events. The sediment can deposit in a runoff-measuring structure and give erroneous readings. The drop-box weir (DBW) is one of only a few flow-measuring devices capable of measuring sediment-laden flows. Recent studies have ...

  10. Quantile hydrologic model selection and model structure deficiency assessment: 2. Applications

    NASA Astrophysics Data System (ADS)

    Pande, Saket

    2013-09-01

    Quantile hydrologic model selection and structure deficiency assessment is applied in three case studies. The performance of quantile model selection problem is rigorously evaluated using a model structure on the French Broad river basin data set. The case study shows that quantile model selection encompasses model selection strategies based on summary statistics and that it is equivalent to maximum likelihood estimation under certain likelihood functions. It also shows that quantile model predictions are fairly robust. The second case study is of a parsimonious hydrological model for dry land areas in Western India. The case study shows that an intuitive improvement in the model structure leads to reductions in asymmetric loss function values for all considered quantiles. The asymmetric loss function is a quantile specific metric that is minimized to obtain a quantile specific prediction model. The case study provides evidence that a quantile-wise reduction in the asymmetric loss function is a robust indicator of model structure improvement. Finally a case study of modeling daily streamflow for the Guadalupe River basin is presented. A model structure that is least deficient for the study area is identified from nine different model structures based on quantile structural deficiency assessment. The nine model structures differ in interception, routing, overland flow and base flow conceptualizations. The three case studies suggest that quantile model selection and deficiency assessment provides a robust mechanism to compare deficiencies of different model structures and helps to identify better model structures. In addition to its novelty, quantile hydrologic model selection is a frequentist approach that seeks to complement existing Bayesian approaches to hydrological model uncertainty.

  11. Analysis and modeling of extreme temperatures in several cities in northwestern Mexico under climate change conditions

    NASA Astrophysics Data System (ADS)

    García-Cueto, O. Rafael; Cavazos, M. Tereza; de Grau, Pamela; Santillán-Soto, Néstor

    2014-04-01

    The generalized extreme value distribution is applied in this article to model the statistical behavior of the maximum and minimum temperature distribution tails in four cities of Baja California in northwestern Mexico, using data from 1950-2010. The approach used of the maximum of annual time blocks. Temporal trends were included as covariates in the location parameter (μ), which resulted in significant improvements to the proposed models, particularly for the extreme maximum temperature values in the cities of Mexicali, Tijuana, and Tecate, and the extreme minimum temperature values in Mexicali and Ensenada. These models were used to estimate future probabilities over the next 100 years (2015-2110) for different time periods, and they were compared with changes in the extreme (P90th and P10th) percentiles of maximum and minimum temperature scenarios for a set of six general circulation models under low (RCP4.5) and high (RCP8.5) radiative forcings. By the end of the twenty-first century, the scenarios of the changes in extreme maximum summer temperature are of the same order in both the statistical model and the high radiative scenario (increases of 4-5 °C). The low radiative scenario is more conservative (increases of 2-3 °C). The winter scenario shows that minimum temperatures could be less severe; the temperature increases suggested by the probabilistic model are greater than those projected for the end of the century by the set of global models under RCP4.5 and RCP8.5 scenarios. The likely impacts on the region are discussed.

  12. A comparative assessment of statistical methods for extreme weather analysis

    NASA Astrophysics Data System (ADS)

    Schlögl, Matthias; Laaha, Gregor

    2017-04-01

    Extreme weather exposure assessment is of major importance for scientists and practitioners alike. We compare different extreme value approaches and fitting methods with respect to their value for assessing extreme precipitation and temperature impacts. Based on an Austrian data set from 25 meteorological stations representing diverse meteorological conditions, we assess the added value of partial duration series over the standardly used annual maxima series in order to give recommendations for performing extreme value statistics of meteorological hazards. Results show the merits of the robust L-moment estimation, which yielded better results than maximum likelihood estimation in 62 % of all cases. At the same time, results question the general assumption of the threshold excess approach (employing partial duration series, PDS) being superior to the block maxima approach (employing annual maxima series, AMS) due to information gain. For low return periods (non-extreme events) the PDS approach tends to overestimate return levels as compared to the AMS approach, whereas an opposite behavior was found for high return levels (extreme events). In extreme cases, an inappropriate threshold was shown to lead to considerable biases that may outperform the possible gain of information from including additional extreme events by far. This effect was neither visible from the square-root criterion, nor from standardly used graphical diagnosis (mean residual life plot), but from a direct comparison of AMS and PDS in synoptic quantile plots. We therefore recommend performing AMS and PDS approaches simultaneously in order to select the best suited approach. This will make the analyses more robust, in cases where threshold selection and dependency introduces biases to the PDS approach, but also in cases where the AMS contains non-extreme events that may introduce similar biases. For assessing the performance of extreme events we recommend conditional performance measures that focus

  13. Peptide synthesis in aqueous environments: the role of extreme conditions on peptide bond formation and peptide hydrolysis.

    PubMed

    Schreiner, Eduard; Nair, Nisanth N; Marx, Dominik

    2009-09-30

    The mechanisms and free energetics underlying the formation of peptides from alpha-amino acids and alpha-amino acid N-carboxyanhydrides (NCAs) in bulk water at both ambient and extreme temperature and pressure conditions were investigated using accelerated ab initio molecular dynamics. In particular, peptide bond formation using an activated amino acid in form of its NCA, subsequent decarboxylation, as well as hydrolysis of the formed peptide were studied using glycine. It is shown to what extent thermodynamic conditions affect the reaction mechanisms qualitatively and the energetics quantitatively in solution. In particular, the zwitterionic intermediate in the peptidization step found in ambient water degenerates into a transient species in hot-pressurized water, whereas the hydrolysis reaction is found to follow qualitatively different pathways at ambient and extreme conditions. The work also quantifies the impact of extreme solvent conditions on both peptide bond formation and peptide hydrolysis in aqueous media. Beyond the specific case, the results provide important insights into how elevated temperatures and increased pressures affect organic reactions in aqueous solutions.

  14. Density functional theory (DFT) studies of hydrogen rich solids and boron carbide under extreme conditions

    NASA Astrophysics Data System (ADS)

    Shamp, Andrew James

    Since the first prediction that compressed hydrogen would metallize in 1935 and the further prediction that the metallic allotrope would be a superconductor at high temperatures, metallic hydrogen has been termed the "holy grail" of high-pressure science. A tremendous amount of theoretical and experimental research has been carried out, with the ultimate goal of metallizing hydrogen via the application of external pressure. It has been previously proposed that doping hydrogen with another element can lower the pressure at which metallization occurs. A number of experimental and theoretical studies have investigated doping hydrogen by either a group XIII or XIV element. Experiments in diamond anvil cells have illustrated that it is indeed possible to synthesize hydrogen-rich phases under conditions of extreme pressures, and SiH4 (H2)2, GeH4(H2) n, and Xe(H2)n have been shown to behave as true compounds. The focus herein is on the theoretical exploration of hydrogen-rich phases with novel stoichiometries, which contain a dopant element up to pressures of 350 GPa. In particular, the alkali-metal and alkaline Earth metal polyhydrides (MHn where n > 1) have been considered. Within this thesis the XtalOpt evolutionary algorithm was employed in order to complete this work, and predict the most stable structures of cesium and beryllium polyhydrides under pressure. In addition, we explore the possibility of mixing excess hydrogen with an electronegative element, iodine and phosphorus. The phases found are examined via detailed first principles calculations. In addition, because of its outstanding hardness, thermodynamic stability, low density, electronic properties, thermal stability, and high melting point boron carbide has many uses: i.e. as a refractory material, in abrasive powders and ballistics, as a neutron radiation absorbent, and in electronic applications. However, little is known about the behavior of boron carbide when under the external stress of pressure. The

  15. Influence of quality control variables on failure of graphite/epoxy under extreme moisture conditions

    NASA Technical Reports Server (NTRS)

    Clements, L. L.; Lee, P. R.

    1980-01-01

    Tension tests on graphite/epoxy composites were performed to determine the influence of various quality control variables on failure strength as a function of moisture and moderate temperatures. The extremely high and low moisture contents investigated were found to have less effect upon properties than did temperature or the quality control variables of specimen flaws and prepreg batch to batch variations. In particular, specimen flaws were found to drastically reduce the predicted strength of the composite, whereas specimens from different batches of prepreg displayed differences in strength as a function of temperature and extreme moisture exposure. The findings illustrate the need for careful specimen preparation, studies of flaw sensitivity, and careful quality control in any study of composite materials.

  16. Influence of quality control variables on failure of graphite/epoxy under extreme moisture conditions

    NASA Technical Reports Server (NTRS)

    Clements, L. L.; Lee, P. R.

    1982-01-01

    Tension tests on graphite/epoxy composites were performed to determine the influence of various quality control variables on failure strength as a function of moisture and moderate temperatures. The extremely high and low moisture contents investigated were found to have less effect upon properties than did temperature or the quality control variables of specimen flaws and prepreg batch to batch variations. In particular, specimen flaws were found to drastically reduce the predicted strength of the composite, whereas specimens from different batches of prepreg displayed differences in strength as a function of temperature and extreme moisture exposure. The findings illustrate the need for careful specimen preparation, studies of flaw sensitvity, and careful quality control in any study of composite materials. Previously announced in STAR as N80-33493

  17. A First-Principles Multi-phase Equation of State of Carbon under Extreme Conditions

    SciTech Connect

    Correa, A A; Benedict, X L; Young, D A; Schwegler, E; Bonev, S A

    2008-02-01

    We describe the construction of a multi-phase equation of state for carbon at extreme pressures based on ab initio electronic structure calculations of two solid phases (diamond and BC8) and the liquid. Solid-phase free energies are built from knowledge of the cold curves and phonon calculations, together with direct ab initio molecular dynamics calculations of the equation of state, which are used to extract anharmonic corrections to the phonon free energy. The liquid free energy is constructed based on results from molecular dynamics calculations and constraints determined from previously calculated melting curves, assuming a simple solid-like free energy model. The resulting equation of state is extended to extreme densities and temperatures with a Thomas Fermi-based free energy model. Comparisons to available experimental results are discussed.

  18. Response of shoal grass, Halodule wrightii, to extreme winter conditions in the Lower Laguna Madre, Texas

    USGS Publications Warehouse

    Hicks, D.W.; Onuf, C.P.; Tunnell, J.W.

    1998-01-01

    Effects of a severe freeze on the shoal grass, Halodule wrightii, were documented through analysis of temporal and spatial trends in below-ground biomass. The coincidence of the second lowest temperature (-10.6??C) in 107 years of record, 56 consecutive hours below freezing, high winds and extremely low water levels exposed the Laguna Madre, TX, to the most severe cold stress in over a century. H. wrightii tolerated this extreme freeze event. Annual pre- and post-freeze surveys indicated that below-ground biomass estimated from volume was Unaffected by the freeze event. Nor was there any post-freeze change in biomass among intertidal sites directly exposed to freezing air temperatures relative to subtidal sites which remained submerged during the freezing period.

  19. An application of quantile random forests for predictive mapping of forest attributes

    Treesearch

    E.A. Freeman; G.G. Moisen

    2015-01-01

    Increasingly, random forest models are used in predictive mapping of forest attributes. Traditional random forests output the mean prediction from the random trees. Quantile regression forests (QRF) is an extension of random forests developed by Nicolai Meinshausen that provides non-parametric estimates of the median predicted value as well as prediction quantiles. It...

  20. Influences of spatial and temporal variation on fish-habitat relationships defined by regression quantiles

    Treesearch

    Jason B. Dunham; Brian S. Cade; James W. Terrell

    2002-01-01

    We used regression quantiles to model potentially limiting relationships between the standing crop of cutthroat trout Oncorhynchus clarki and measures of stream channel morphology. Regression quantile models indicated that variation in fish density was inversely related to the width:depth ratio of streams but not to stream width or depth alone. The...

  1. Sediment Dynamics Within Buffer Zone and Sinkhole Splay Areas Under Extreme Soil Disturbance Conditions

    NASA Astrophysics Data System (ADS)

    Schoonover, Jon E.; Crim, Jackie F.; Williard, Karl W. J.; Groninger, John W.; Zaczek, James J.; Pattumma, Klairoong

    2015-09-01

    Sedimentation dynamics were assessed in sinkholes within training areas at Ft. Knox Military Installation, a karst landscape subjected to decades of tracked vehicle use and extreme soil disturbance. Sinkholes sampled were sediment-laden and behaved as intermittent ponds. Dendrogeomorphic analyses were conducted using willow trees ( Salix spp.) located around the edge of 18 sinkholes to estimate historical sedimentation rates, and buried bottles were installed in 20 sinkholes at the center, outer edge, and at the midpoint between the center and edge to estimate annual sedimentation rates. Sedimentation data were coupled with vegetation characteristics of sinkhole buffers to determine relationships among these variables. The dendrogeomorphic method estimated an average accumulation rate of 1.27 cm year-1 translating to a sediment loss rate of 46.1 metric ton year-1 from the training areas. However, sediment export to sinkholes was estimated to be much greater (118.6 metric ton year-1) via the bottle method. These data suggest that the latter method provided a more accurate estimate since accumulation was greater in the center of sinkholes compared to the periphery where dendrogeomorphic data were collected. Vegetation data were not tightly correlated with sedimentation rates, suggesting that further research is needed to identify a viable proxy for direct measures of sediment accumulation in this extreme deposition environment. Mitigation activities for the sinkholes at Ft. Knox's tank training area, and other heavily disturbed karst environments where extreme sedimentation exists, should consider focusing on flow path and splay area management.

  2. Operational flood management under large-scale extreme conditions, using the example of the Middle Elbe

    NASA Astrophysics Data System (ADS)

    Kron, A.; Nestmann, F.; Schlüter, I.; Schädler, G.; Kottmeier, C.; Helms, M.; Mikovec, R.; Ihringer, J.; Musall, M.; Oberle, P.; Saucke, U.; Bieberstein, A.; Daåhelka, J.; Krejčí, J.

    2010-06-01

    In addition to precautionary or technical flood protection measures, short-term strategies of the operational management, i.e. the initiation and co-ordination of preventive measures during and/or before a flood event are crucially for the reduction of the flood damages. This applies especially for extreme flood events. These events are rare, but may cause a protection measure to be overtopped or even to fail and be destroyed. In such extreme cases, reliable decisions must be made and emergency measures need to be carried out to prevent even larger damages from occurring. Based on improved methods for meteorological and hydrological modelling a range of (physically based) extreme flood scenarios can be derived from historical events by modification of air temperature and humidity, shifting of weather fields and recombination of flood relevant event characteristics. By coupling the large scale models with hydraulic and geotechnical models, the whole flood-process-chain can be analysed right down to the local scale. With the developed GIS-based tools for hydraulic modelling FlowGIS and the Dike-Information-System, (IS-dikes) it is possible to quantify the endangering shortly before or even during a flood event, so the decision makers can evaluate possible options for action in operational mode.

  3. Study on Strength of Hybrid Mortar Synthesis with Epoxy Resin, Fly Ash and Quarry Dust Under Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Sudheer, P.; Muni Reddy, M. G., Dr.; Adiseshu, S., Dr.

    2017-08-01

    Blend and characterization of Bisphenol-A diglycidyl ether based thermosetting polymer mortar comprising an epoxy resin, Fly ash and Quarry dust are presented here for the strength study. The specimens have been prepared by means of an innovative process in Extreme conditions of commercial epoxy resin, Fly ash and Quarry dust based paste. In this way, thermosetting based hybrid mortars characterized by a different contents of normalized Fly ash and Quarry dust by a homogeneous distribution of the resin have been attained. Once hardened, these new composite materials show improved compressive strength and toughness in respect to both the Fly ash and Rock sand pastes since the Resin provides a more cohesive microstructure, with a reduced number of micro cracks. The micro structural characterization allows pointing out the presence of an Interfacial Transition Zone similar to that observed in cement based mortars. A correlation between micro-structural features and mechanical properties of the mortar has also been studied in Extreme conditions.

  4. Quantile regression neural networks: Implementation in R and application to precipitation downscaling

    NASA Astrophysics Data System (ADS)

    Cannon, Alex J.

    2011-09-01

    The qrnn package for R implements the quantile regression neural network, which is an artificial neural network extension of linear quantile regression. The model formulation follows from previous work on the estimation of censored regression quantiles. The result is a nonparametric, nonlinear model suitable for making probabilistic predictions of mixed discrete-continuous variables like precipitation amounts, wind speeds, or pollutant concentrations, as well as continuous variables. A differentiable approximation to the quantile regression error function is adopted so that gradient-based optimization algorithms can be used to estimate model parameters. Weight penalty and bootstrap aggregation methods are used to avoid overfitting. For convenience, functions for quantile-based probability density, cumulative distribution, and inverse cumulative distribution functions are also provided. Package functions are demonstrated on a simple precipitation downscaling task.

  5. Hydrolysis and acidification of dewatered sludge under mesophilic, thermophilic and extreme thermophilic conditions: effect of pH.

    PubMed

    Liu, Xiaoguang; Dong, Bin; Dai, Xiaohu

    2013-11-01

    This study investigated the effect of pH (uncontrolled, 8.0, 10.0 and 12.0) and temperature (mesophilic, thermophilic and extreme thermophilic) on hydrolysis and acidification of dewatered sludge in 7-day batch fermentation experiment. Solublization of COD, protein and carbohydrates as well as concentration and composition of VFAs were investigated. Sludge hydrolysis was enhanced with higher pH and temperature. The maximum SCOD, soluble protein and carbohydrates was observed at pH 12.0 at extreme thermophilic condition. The maximum VFAs yield was obtained at thermophilic and was 2.15 times that at mesophilic condition, but it took more time to reach the maximum. The VFAs consisted of acetic, propionic, iso-butyric, n-butyric, iso-valeric, and n-valeric acids, and acetic acid was the prevalent product in most cases except for uncontrolled pH and pH 8.0 at mesophilic condition. The methane production was as follows: pH 8.0>pH 10.0>uncontrolled (0.015)>pH 12.0; mesophilic>thermophilic>extreme thermophilic. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Nonstationary frequency analysis of extreme daily precipitation amounts in Southeastern Canada using a peaks-over-threshold approach

    NASA Astrophysics Data System (ADS)

    Thiombiano, Alida N.; El Adlouni, Salaheddine; St-Hilaire, André; Ouarda, Taha B. M. J.; El-Jabi, Nassir

    2017-07-01

    In this paper, a statistical inference of Southeastern Canada extreme daily precipitation amounts is proposed using a classical nonstationary peaks-over-threshold model. Indeed, the generalized Pareto distribution (GPD) is fitted to excess time series derived from annual averages of independent precipitation amount events above a fixed threshold, the 99th percentile. Only the scale parameter of the fitted distribution is allowed to vary as a function of a covariate. This variability is modeled using B-spline function. Nonlinear correlation and cross-wavelet analysis allowed identifying two dominant climate indices as covariates in the study area, Arctic Oscillation (AO) and Pacific North American (PNA). The nonstationary frequency analysis showed that there is an east-west behavior of the AO index effects on extreme daily precipitation amounts in the study area. Indeed, the higher quantiles of these events are conditional to the AO positive phase in Atlantic Canada, while those in the more southeastern part of Canada, especially in Southern Quebec and Ontario, are negatively related to AO. The negative phase of PNA also gives the best significant correlation in these regions. Moreover, a regression analysis between AO (PNA) index and conditional quantiles provided slope values for the positive phase of the index on the one hand and the negative phase and on the other hand. This statistic allows computing a slope ratio which permits to sustain the nonlinear relation assumption between climate indices and precipitation and the development of the nonstationary GPD model for Southeastern Canada extremes precipitation modeling.

  7. Differing Response of Extreme Precipitation to Changing Boundary Conditions in Simulations with Parametrized and Explicit Convection

    NASA Astrophysics Data System (ADS)

    Meredith, Edmund; Maraun, Douglas; Semenov, Vladimir; Park, Wonsun

    2015-04-01

    Recent studies have shown that the representation of extreme precipitation in climate models is much more sensitive to model resolution than that of mean precipitation. With global and regional circulation models simulating both present and future climates at ever-increasing resolution, it is only a matter of time before convection resolving climate projections become the norm. In the meantime, regional climate models provide an efficient and inexpensive tool to assess what, if any, impact explicitly resolved convection may have on the representation of precipitation extremes in warmer climates with enhanced boundary forcings. To compare the response of precipitation extremes in models with parametrized and explicitly resolved convection to changing boundary forcings, we select the July 2012 precipitation extreme near the Black Sea town of Krymsk as a recent showcase example. The event was related to a slow moving low pressure system crossing the eastern Black Sea, advecting warm and moist air towards the coast. Two waves of convection resulted in precipitation totals that dwarfed all previous events in the instrumental record, dating back to the 1930s, and over 170 deaths. We carry out ensemble sensitivity experiments with a triply nested configuration of the WRF regional model, for a domain covering the eastern Black Sea. The event is simulated at 15 km, 3 km and 600 m resolution. The model's ability to reproduce the event with observed forcings is first verified, before a series of additional ensembles with altered boundary forcings, in our case sea surface temperature (SST), is created. These ensembles consist of subtracting (adding) the 1982 - 2012 trend in Black Sea SST from (to) the observed 2012 SST field in 20% increments, giving a total of 11 ensembles whose SST differ from the observed field by between -100% and +100% of the warming trend. Aggregating all data to the 15 km grid, we compare the responses of hourly precipitation maxima to incrementally

  8. Intestinal anisakiasis can cause intussusception in adults: an extremely rare condition.

    PubMed

    Miura, Tomofumi; Iwaya, Akira; Shimizu, Takao; Tsuchiya, Junpei; Nakamura, Junichiro; Yamada, Satoshi; Miura, Tsutomu; Yanagi, Masahiko; Usuda, Hiroyuki; Emura, Iwao; Takahashi, Toru

    2010-04-14

    We report an extremely rare case of adult intussusception caused by anisakiasis. A 41-year-old man was admitted into our hospital for right lower abdominal colicky pain. Ultrasonography and computed tomography revealed the presence of intussusception. As pneumo-dynamic resolution by colonoscopy failed, surgery was performed. The anisakis body was found in the submucosal layer of the resection specimen. The patient was discharged 9 d after the operation. Anisakiasis may cause intussusception in any country where sushi or sashimi now exists as a popular food. If suspicious, detailed clinical interview as to food intake prior to symptom development is crucial.

  9. Quantile-Quantile Plots:. AN Approach for the Inter-Species Comparison of Promoter Architecture in Eukaryotes

    NASA Astrophysics Data System (ADS)

    Feldmeier, Kaspar; Kilian, Joachim; Harter, Klaus; Wanke, Dierk; Berendzen, Kenneth W.

    2011-01-01

    Regulatory non-coding DNA is important to drive gene transcription and thereby influence mRNA and consequently protein abundance. Therefore, biologists and bioinformation scientists aim to extract meaningful information from these sequence regions, in particular upstream regulation regions called promoters, and conclude on regulatory sequence function. While some approaches have been successful for single genes or a single genome, it is an open question whether information on promoter function can readily be transferred between different species. Thus, it is useful for biologists to know more about the general structure and composition of promoters including the occurrence of cisregulatory DNA-elements (CREs) to be able to compare promoter architecture between organisms. To approach this task, we utilized the fully sequenced genomes of the plant model organisms: mouse-ear cress (Arabidopsis thaliana), western balsam poplar (Populus trichocarpa), Sorghum bicolor and rice (Oryza sativa). For the interspecies comparison we made use of quantile-quantile (QQ)-plots of the variances of hexanucleotides or known functional CREs of core-promoter regions. Here, we suggest that the differences in promoter architecture correlate with the sizes of the intergenic space, i.e. regions, in which the promoters are located. In contrast, analysis of CREs is hampered by the general lack of well characterized transcription factor-CRE-relationships.

  10. Enhancing Local Climate Projections of Precipitation: Assets and Limitations of Quantile Mapping Techniques for Statistical Downscaling

    NASA Astrophysics Data System (ADS)

    Ivanov, Martin; Kotlarski, Sven; Schär, Christoph

    2015-04-01

    The Swiss CH2011 scenarios provide a portfolio of climate change scenarios for the region of Switzerland, specifically tailored for use in climate impact research. Although widely applied by a variety of end-users, these scenarios are subject to several limitations related to the underlying delta change methodology. Examples are difficulties to appropriately account for changes in the spatio-temporal variability of meteorological fields and for changes in extreme events. The recently launched ELAPSE project (Enhancing local and regional climate change projections for Switzerland) is connected to the EU COST Action VALUE (www.value-cost.eu) and aims at complementing CH2011 by further scenario products, including a bias-corrected version of daily scenarios at the site scale. For this purpose the well-established empirical quantile mapping (QM) methodology is employed. Here, daily temperature and precipitation output of 15 GCM-RCM model chains of the ENSEMBLES project is downscaled and bias-corrected to match observations at weather stations in Switzerland. We consider established QM techniques based on all empirical quantiles or linear interpolation between the empirical percentiles. In an attempt to improve the downscaling of extreme precipitation events, we also apply a parametric approximation of the daily precipitation distribution by a dynamically weighted mixture of a Gamma distribution for the bulk and a Pareto distribution for the right tail for the first time in the context of QM. All techniques are evaluated and intercompared in a cross-validation framework. The statistical downscaling substantially improves virtually all considered distributional and temporal characteristics as well as their spatial distribution. The empirical methods have in general very similar performances. The parametric method does not show an improvement over the empirical ones. Critical sites and seasons are highlighted and discussed. Special emphasis is placed on investigating the

  11. Impact of urban WWTP and CSO fluxes on river peak flow extremes under current and future climate conditions.

    PubMed

    Keupers, Ingrid; Willems, Patrick

    2013-01-01

    The impact of urban water fluxes on the river system outflow of the Grote Nete catchment (Belgium) was studied. First the impact of the Waste Water Treatment Plant (WWTP) and the Combined Sewer Overflow (CSO) outflows on the river system for the current climatic conditions was determined by simulating the urban fluxes as point sources in a detailed, hydrodynamic river model. Comparison was made of the simulation results on peak flow extremes with and without the urban point sources. In a second step, the impact of climate change scenarios on the urban fluxes and the consequent impacts on the river flow extremes were studied. It is shown that the change in the 10-year return period hourly peak flow discharge due to climate change (-14% to +45%) was in the same order of magnitude as the change due to the urban fluxes (+5%) in current climate conditions. Different climate change scenarios do not change the impact of the urban fluxes much except for the climate scenario that involves a strong increase in rainfall extremes in summer. This scenario leads to a strong increase of the impact of the urban fluxes on the river system.

  12. Carbon under extreme conditions: phase boundaries and electronic properties from first-principles theory.

    PubMed

    Correa, Alfredo A; Bonev, Stanimir A; Galli, Giulia

    2006-01-31

    At high pressure and temperature, the phase diagram of elemental carbon is poorly known. We present predictions of diamond and BC8 melting lines and their phase boundary in the solid phase, as obtained from first-principles calculations. Maxima are found in both melting lines, with a triple point located at approximately 850 GPa and approximately 7,400 K. Our results show that hot, compressed diamond is a semiconductor that undergoes metalization upon melting. In contrast, in the stability range of BC8, an insulator to metal transition is likely to occur in the solid phase. Close to the diamond/liquid and BC8/liquid boundaries, molten carbon is a low-coordinated metal retaining some covalent character in its bonding up to extreme pressures. Our results provide constraints on the carbon equation of state, which is of critical importance for devising models of Neptune, Uranus, and white dwarf stars, as well as of extrasolar carbon-rich planets.

  13. Carbon under extreme conditions: Phase boundaries and electronic properties from first-principles theory

    SciTech Connect

    Correa, Alfredo A.; Bonev, Stanimir A.; Galli, Giulia

    2006-01-23

    At high pressure and temperature, the phase diagram of elemental carbon is poorly known. We present predictions of diamond and BC8 melting lines and their phase boundary in the solid phase, as obtained from first-principles calculations. Maxima are found in both melting lines, with a triple point located at ≈ 850 GPa and ≈ 7,400 K. Our results show that hot, compressed diamond is a semiconductor that undergoes metalization upon melting. In contrast, in the stability range of BC8, an insulator to metal transition is likely to occur in the solid phase. Close to the diamond/liquid and BC8/liquid boundaries, molten carbon is a low-coordinated metal retaining some covalent character in its bonding up to extreme pressures. Lastly, our results provide constraints on the carbon equation of state, which is of critical importance for devising models of Neptune, Uranus, and white dwarf stars, as well as of extrasolar carbon-rich planets.

  14. Water Under the Extreme Conditions of Planetary Interiors: Symmetric Hydrogen Bonding in the Superionic Phase

    SciTech Connect

    Goldman, N; Fried, L E

    2005-07-08

    The predicted superionic phase of water is investigated via ab initio molecular dynamics at densities of 2.0-3.0 g/cc (34-115 GPa) along the 2000 K isotherm. They find that extremely rapid (superionic) diffusion of protons occurs in a fluid phase at pressures between 34 and 58 GPa. A transition to a stable body-centered cubic (bcc) O lattice with superionic proton conductivity is observed between 70 and 75 GPa, a much higher pressure than suggested in prior work. They find that all molecular species at pressures greater than 75 GPa are too short lived to be classified as bound states. Above 95 GPa, a transient network phase is found characterized by symmetric O-H hydrogen bonding with nearly 50% covalent character.

  15. Equation of state density models for hydrocarbons in ultradeep reservoirs at extreme temperature and pressure conditions

    NASA Astrophysics Data System (ADS)

    Wu, Yue; Bamgbade, Babatunde A.; Burgess, Ward A.; Tapriyal, Deepak; Baled, Hseen O.; Enick, Robert M.; McHugh, Mark A.

    2013-10-01

    The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.

  16. [Increased cortisol levels, frostbite and effects on the muscles and skeleton during extreme polar conditions].

    PubMed

    Steine, Kjetil; Røseth, Arne G; Sandbaek, Gunnar; Murison, Robert; Slagsvold, Carl-Erik; Keller, Anne; Falch, Jan A

    2003-12-23

    We wanted to record physiological changes, injuries and illnesses during a long sledge expedition in North Canada. The expedition consisted of four men aged 41 to 50, and 16 polar dogs. Measurements of cortisol in saliva were performed before, during and after the expedition. Frostbites and other injuries were registered continuously. Body weight and muscle, fat and bone mass were measured by dual X-ray absorptiometry scanning, and strength and endurance of shoulders, knees and back were tested. The group encountered extreme frost (-30 to -42 degrees C day temperature), wind, unexpected amounts of pack ice, and poorly motivated dogs. The participants showed increased free cortisol levels during their stay on the ice, probably because of increased mental stress. Three got first degree and two second-degree frostbites, but the affected areas were normal on vascular examination five months later. All members increased their muscle mass, but muscle strength and endurance remained unchanged.

  17. The Effects of Visual Field Conditions on Electromyography of the Lower Extremities during Reaching Tasks in Healthy Adults

    PubMed Central

    Park, Jun Hyuk; Lee, Kyeong Soon; Oh, Tae Young

    2014-01-01

    [Purpose] The purpose of this study was to identify the effects of visual field condition on electromyography of the lower extremities during arm reaching in healthy adults, and to compare differences in electromyography of the lower extremities between young and old adults according to visual fields condition. [Subjects and Methods] Twenty-nine young persons in their 20s and 19 elderly persons in their 60s, a total of 48 persons, participated in this study. Prior to participation in the study, each subject signed an informed consent form to comply with ethics guidelines dictated by the ethics committee for research at Silla University, Korea. We collected the muscle activation data for both of tibialis anterior and gastrocnemius muscle during reaching by subjects using electromyography. Data analysis with SPSS for Window Version 20.0 was performed using repeated one-way analysis of variance according to visual fields and age. [Results] There were no significantly differences between subjects in their 20s and 60s to visual field conditions except for left tibialis anterior muscle activation during left-side reaching. Left tibialis anterior muscle activation in subjects in their 60s was higher than in subjects in their 20s during left-side reaching. [Conclusion] We determined that tibialis anterior muscle activation in subjects in their 60s was higher than in subjects in their 20s. We suggest that visual field conditions are the important factor for physical therapy interventions to improve balance and priority of intervention . PMID:24764630

  18. Extreme value modelling of Ghana stock exchange index.

    PubMed

    Nortey, Ezekiel N N; Asare, Kwabena; Mettle, Felix Okoe

    2015-01-01

    Modelling of extreme events has always been of interest in fields such as hydrology and meteorology. However, after the recent global financial crises, appropriate models for modelling of such rare events leading to these crises have become quite essential in the finance and risk management fields. This paper models the extreme values of the Ghana stock exchange all-shares index (2000-2010) by applying the extreme value theory (EVT) to fit a model to the tails of the daily stock returns data. A conditional approach of the EVT was preferred and hence an ARMA-GARCH model was fitted to the data to correct for the effects of autocorrelation and conditional heteroscedastic terms present in the returns series, before the EVT method was applied. The Peak Over Threshold approach of the EVT, which fits a Generalized Pareto Distribution (GPD) model to excesses above a certain selected threshold, was employed. Maximum likelihood estimates of the model parameters were obtained and the model's goodness of fit was assessed graphically using Q-Q, P-P and density plots. The findings indicate that the GPD provides an adequate fit to the data of excesses. The size of the extreme daily Ghanaian stock market movements were then computed using the value at risk and expected shortfall risk measures at some high quantiles, based on the fitted GPD model.

  19. Analysis of the impacts of EC-Earth Global Circulation Model in the RCP45 climate change scenario on maximum daily streamflow quantiles at global scale

    NASA Astrophysics Data System (ADS)

    Silvestro, Francesco; Campo, Lorenzo; Rudari, Roberto; Herold, Christian; De Angeli, Silvia; Gabellani, Simone; D'Andrea, Mirko; Rodila, Denisa

    2016-04-01

    Climate changes can have an impact on various components of hydrological cycle. From a risk assessment point of view it is certainly interesting understanding how extreme streamflow values can change as a consequence of climate variability. In order to do this the outputs of a climate model (EC-EARTH) that accounts for a standard climate scenario were used to feed a hydrological model and to generate 140 years (1960-2100) of continuous streamflow simulations in a large number of stations that cover all the world. These time series were then post-processed in order to evaluate how annual daily maximum streamflow quantiles change because of climate scenarios. The analysis highlights that in many cases there is an increment or a decrease of the quantiles for fixed return periods, but only in a reduced number of situations these variation lay out of the confidence intervals of the quantiles estimated in current climate. The analysis was carried out on over 5000 stations distributed in all continents and spanned the period 1960-2100 according to the climate scenario RCP45.

  20. Spectral distance decay: Assessing species beta-diversity by quantile regression

    USGS Publications Warehouse

    Rocchinl, D.; Nagendra, H.; Ghate, R.; Cade, B.S.

    2009-01-01

    Remotely sensed data represents key information for characterizing and estimating biodiversity. Spectral distance among sites has proven to be a powerful approach for detecting species composition variability. Regression analysis of species similarity versus spectral distance may allow us to quantitatively estimate how beta-diversity in species changes with respect to spectral and ecological variability. In classical regression analysis, the residual sum of squares is minimized for the mean of the dependent variable distribution. However, many ecological datasets are characterized by a high number of zeroes that can add noise to the regression model. Quantile regression can be used to evaluate trend in the upper quantiles rather than a mean trend across the whole distribution of the dependent variable. In this paper, we used ordinary least square (ols) and quantile regression to estimate the decay of species similarity versus spectral distance. The achieved decay rates were statistically nonzero (p < 0.05) considering both ols and quantile regression. Nonetheless, ols regression estimate of mean decay rate was only half the decay rate indicated by the upper quantiles. Moreover, the intercept value, representing the similarity reached when spectral distance approaches zero, was very low compared with the intercepts of upper quantiles, which detected high species similarity when habitats are more similar. In this paper we demonstrated the power of using quantile regressions applied to spectral distance decay in order to reveal species diversity patterns otherwise lost or underestimated by ordinary least square regression. ?? 2009 American Society for Photogrammetry and Remote Sensing.

  1. Hyperstoichiometric Oxygen in Fluorite-type U3O8 Formed at Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Fuxiang; Lang, Maik; Ewing, Rod; Department of Earth and Environmental Sciences Team

    2014-03-01

    U3O8 was obtained by annealing UO3 in a reducing atmosphere at 200 °C. Powder sample of β-U3O8 was pressurized at room temperature up to 37.5 GPa and XRD patterns clearly indicated that a phase transition occurred between 3-11 GPa. The high-pressure phase is a fluorite-like structure. The high-pressure phase was then laser heated to over 1700 K in the diamond anvil cell at high pressure conditions. No phase transition was found at high pressure/ temperature conditions, and the fluorite-like structure of U3O8 is even fully quenchable. The lattice parameter of the fluorite-like high-pressure phase is 5.425 Å at ambient conditions, which is smaller than that of the stoichiometric UO2. Previous experiments have shown that the stoichiometric uranium dioxide (UO2) is not stable at high pressure conditions and starts to transform to a cotunnite structure at ~ 30 GPa. When heating the sample at high pressure, the critical transition pressure is greatly reduced. However, the fluorite-like high-pressure phase of U3O8 is very stable at high pressure/high temperature conditions. The enhanced phase stability is believed to be related to the presence of extra oxygen (or U vacancies) in the structure.

  2. [Deep-sea research ground for the study of living matter properties in extreme conditions].

    PubMed

    Polikarpov, G G

    2011-01-01

    The Black Sea hollow bottom is a promising research ground in the field of deep-sea radiochemoecology and exobiology. It has turned out to be at the intersection of the earth and cosmic scientific interests such as deep-sea marine radiochemoecology from the perspective of the study of extreme biogeocenological properties of the Earth biosphere and exobiology from the standpoint of the study of life phenomena (living matter) outside the Earth biosphere, i.e. on other planets and during hypothetical transfer of spores in the outer space. The potential of this ground is substantiated with the data published by the author and co-workers on accumulation of 90Sr, 137Cs and Pu isotopes with silts of bathyal pelo-contour, on the quality of deep-sea hydrogen sulphide waters (after their contact with air) for vital functions of planktonic and benthic aerobes, as well as the species composition of marine, freshwater and terrestrial plants grown from the spores collected from the bottom sediments of the Black Sea bathyal. Discussion was based on V.I. Vernadsky's ideas about the living matter and biosphere, which allowed conclusions about the biospheric and outer space role of the described phenomena.

  3. [ASSESSMENT OF EXTREME FACTORS OF SHIFT WORK IN ARCTIC CONDITIONS BY WORKERS WITH DIFFERENT REGULATORY PROCESSES].

    PubMed

    Korneeva, Ya A; Simonova, N N

    2016-01-01

    A man working on a shift basis in the Arctic, every day is under the influence of various extreme factors which are inevitable for oil and gas indudtry. To adapt to shift work employees use various resources of the individual. The purpose of research is the determination of personal resources of shift workers to overcome the adverse factors of the environment in the Arctic. The study involved 191 builder of main gas pipelines, working in shifts in the Tyumen region (the length of the shift 52 days of arrival) at the age of 23 to 59 (mean age 34.9 ± 8.1) years. Methods: psychological testing, questioning, observation, descriptive statistics, discriminant step by step analysis. There was revealed the correlation between the subjective assessment of the majority of adverse climatic factors in the regulatory process "assessment of results"; production factors--regulatory processes such as flexibility, autonomy, simulation, and the general level of self-regulation; social factors are more associated with the severity of such regulatory processes, flexibility and evaluation of results.

  4. Carbon under extreme conditions: Phase boundaries and electronic properties from first-principles theory

    DOE PAGES

    Correa, Alfredo A.; Bonev, Stanimir A.; Galli, Giulia

    2006-01-23

    At high pressure and temperature, the phase diagram of elemental carbon is poorly known. We present predictions of diamond and BC8 melting lines and their phase boundary in the solid phase, as obtained from first-principles calculations. Maxima are found in both melting lines, with a triple point located at ≈ 850 GPa and ≈ 7,400 K. Our results show that hot, compressed diamond is a semiconductor that undergoes metalization upon melting. In contrast, in the stability range of BC8, an insulator to metal transition is likely to occur in the solid phase. Close to the diamond/liquid and BC8/liquid boundaries, moltenmore » carbon is a low-coordinated metal retaining some covalent character in its bonding up to extreme pressures. Lastly, our results provide constraints on the carbon equation of state, which is of critical importance for devising models of Neptune, Uranus, and white dwarf stars, as well as of extrasolar carbon-rich planets.« less

  5. Carbon under extreme conditions: Phase boundaries and electronic properties from first-principles theory

    PubMed Central

    Correa, Alfredo A.; Bonev, Stanimir A.; Galli, Giulia

    2006-01-01

    At high pressure and temperature, the phase diagram of elemental carbon is poorly known. We present predictions of diamond and BC8 melting lines and their phase boundary in the solid phase, as obtained from first-principles calculations. Maxima are found in both melting lines, with a triple point located at ≈850 GPa and ≈7,400 K. Our results show that hot, compressed diamond is a semiconductor that undergoes metalization upon melting. In contrast, in the stability range of BC8, an insulator to metal transition is likely to occur in the solid phase. Close to the diamond/liquid and BC8/liquid boundaries, molten carbon is a low-coordinated metal retaining some covalent character in its bonding up to extreme pressures. Our results provide constraints on the carbon equation of state, which is of critical importance for devising models of Neptune, Uranus, and white dwarf stars, as well as of extrasolar carbon-rich planets. PMID:16432191

  6. Halophilic archaea on Earth and in space: growth and survival under extreme conditions.

    PubMed

    Oren, Aharon

    2014-12-13

    Salts are abundant on Mars, and any liquid water that is present or may have been present on the planet is expected to be hypersaline. Halophilic archaea (family Halobacteriaceae) are the microorganisms best adapted to life at extremes of salinity on Earth. This paper reviews the properties of the Halobacteriaceae that may make the group good candidates for life also on Mars. Many species resist high UV and gamma radiation levels; one species has survived exposure to vacuum and radiation during a space flight; and there is at least one psychrotolerant species. Halophilic archaea may survive for millions of years within brine inclusions in salt crystals. Many species have different modes of anaerobic metabolism, and some can use light as an energy source using the light-driven proton pump bacteriorhodopsin. They are also highly tolerant to perchlorate, recently shown to be present in Martian soils, and some species can even use perchlorate as an electron acceptor to support anaerobic growth. The presence of characteristic carotenoid pigments (α-bacterioruberin and derivatives) makes the Halobacteriaceae easy to identify by Raman spectroscopy. Thus, if present on Mars, such organisms may be detected by Raman instrumentation planned to explore Mars during the upcoming ExoMars mission.

  7. Different thermal conditions of the extremities affect thermoregulation in clothed man.

    PubMed

    Jeong, W S; Tokura, H

    1993-01-01

    The effects of different types of clothing on human deep body temperature were studied with six healthy male subjects in a supine posture. Two clothing ensembles were employed for the present study: A covered the whole body area with garments except the face (1.97 clo) and B covered only the trunk and the upper half of the extremities with garments (1.53 clo). The experiment was carried out in a climatic chamber at 55% +/- 5% relative humidity under cooling and warming temperatures: the temperature was changed from 22 degrees C to 10 degrees C (cooling) and returned to 22 degrees C again (warming). The major findings were: rectal temperature (T(re)) continued to decrease gradually in A throughout the experiment, whereas in B it increased during cooling, and returned to previous levels during warming. As a result, T(re) and chest skin temperature were maintained at a higher level in B than in A. Internal tissue conductances were greater in A than in B both during cooling and during warming. Thermal comfort appeared to have been influenced more by the rate of skin temperature change than by the level of skin temperature per se. It was concluded that peripheral vasoconstriction in B induced less heat flow from core to shell, and, thus, the core temperature was maintained at a higher level in B than in A.

  8. The critical role of uncertainty in projections of hydrological extremes

    NASA Astrophysics Data System (ADS)

    Meresa, Hadush K.; Romanowicz, Renata J.

    2017-08-01

    This paper aims to quantify the uncertainty in projections of future hydrological extremes in the Biala Tarnowska River at Koszyce gauging station, south Poland. The approach followed is based on several climate projections obtained from the EURO-CORDEX initiative, raw and bias-corrected realizations of catchment precipitation, and flow simulations derived using multiple hydrological model parameter sets. The projections cover the 21st century. Three sources of uncertainty are considered: one related to climate projection ensemble spread, the second related to the uncertainty in hydrological model parameters and the third related to the error in fitting theoretical distribution models to annual extreme flow series. The uncertainty of projected extreme indices related to hydrological model parameters was conditioned on flow observations from the reference period using the generalized likelihood uncertainty estimation (GLUE) approach, with separate criteria for high- and low-flow extremes. Extreme (low and high) flow quantiles were estimated using the generalized extreme value (GEV) distribution at different return periods and were based on two different lengths of the flow time series. A sensitivity analysis based on the analysis of variance (ANOVA) shows that the uncertainty introduced by the hydrological model parameters can be larger than the climate model variability and the distribution fit uncertainty for the low-flow extremes whilst for the high-flow extremes higher uncertainty is observed from climate models than from hydrological parameter and distribution fit uncertainties. This implies that ignoring one of the three uncertainty sources may cause great risk to future hydrological extreme adaptations and water resource planning and management.

  9. Associations of blood pressure with common factors among left-behind farmers in rural China: a cross-sectional study using quantile regression analysis.

    PubMed

    Shen, Xingrong; Li, Kaichun; Chen, Penglai; Feng, Rui; Liang, Han; Tong, Guixian; Chen, Jing; Chai, Jing; Shi, Yong; Xie, Shaoyu; Wang, Debin

    2015-01-01

    The whole range of blood pressure (BP) has important implications. Yet, published studies focus primarily on hypertension and hypotension, the two extremes of BP continuum. This study aims at exploring quantile-specific associations of BP with common factors. The study used cross-sectional survey, collected information about gender, age, education, body mass index (BMI), alcohol intake, diet risk behavior, life event index, physical activity, fasting capillary glucose (FCG), and systolic/diastolic blood pressure (SBP/DBP) and pulse pressure (PP) from farmers living in 18 villages from rural Anhui, China, and performed descriptive and multivariate and quantile regression (QR) analysis of associations of SBP, DBP, or PP with the 9 factors surveyed. A total of 4040 (86.3%) eligible farmers completed the survey. Average hypertension prevalence rate and SBP, DBP, and PP values estimated 43.20 ± 0.50% and 141.37 ± 21.98, 87.76 ± 12.23, and 53.63 ± 15.72 mm Hg, respectively. Multivariate regression analysis revealed that all the 9 factors were significantly (P < 0.05) associated with one or more of SBP, DBP, and PP. QR coefficients of SBP, DBP, or PP with different factors demonstrated divergent patterns and age, BMI, FCG, and life event index showed substantial trends along the quantile axis. Hypertension prevalence rate was high among the farmers. QR modeling provided more detailed view on associations of SBP, DBP, or PP with different factors and uncovered apparent quantile-related patterns for part of the factors. Both the population group studied and the trends in QR coefficients identified merit specific attention.

  10. Extremal properties of conditional entropy and quantum discord for XXZ, symmetric quantum states

    NASA Astrophysics Data System (ADS)

    Yurischev, M. A.

    2017-10-01

    For the XXZ subclass of symmetric two-qubit X states, we study the behavior of quantum conditional entropy S_{cond} as a function of measurement angle θ \\in [0,π /2]. Numerical calculations show that the function S_{cond}(θ ) for X states can have at most one local extremum in the open interval from zero to π /2 (unimodality property). If the extremum is a minimum, the quantum discord displays region with variable (state-dependent) optimal measurement angle θ ^*. Such θ -regions (phases, fractions) are very tiny in the space of X-state parameters. We also discover the cases when the conditional entropy has a local maximum inside the interval (0,π /2). It is remarkable that the maxima exist in surprisingly wide regions, and the boundaries for such regions are defined by the same bifurcation conditions as for those with a minimum.

  11. Changes in some components of the muscle lipids of three freshwater fish species under natural extreme cold and temperate conditions.

    PubMed

    Uysal, K; Bülbül, M; Dönmez, M; Seçkin, A K

    2008-12-01

    Fatty acid composition, conjugated linoleic acid and cholesterol contents in the muscles of three freshwater fish species (Barbus plebejus escherichi, Capoeta capoeta capoeta and Rutilus rutilus) were determined under natural extreme temperate (July) and cold (January) conditions. The aim of the study was to determine whether there were differences in these components of the muscle lipids among these three fish species under extreme natural conditions. Samples were analyzed using gas chromatography. Palmitic, oleic, docosahexaenoic and eicosapentaenoic acids were the predominant fatty acids in all fish in both months. The percentages of polyunsaturated fatty acids, n - 3 polyunsaturated fatty acids, n - 6 polyunsaturated fatty acids and eicosapentaenoic + docosahexaenoic acids in the muscle of B. plebejus escherichi and C. capoeta capoeta were significantly higher in January (P < 0.05) than in July. The ratio of n - 6 to n - 3 polyunsaturated fatty acids was lower than 0.60 in all fish species, with C. capoeta capoeta showing the lowest ratio in January (0.36). The levels of cholesterol and conjugated linoleic acid ranged from 103.46 to 150.10 mg/100 g oil and from 16.27 to 35.45 mg/100 g oil, respectively, for all samples in both months. There were no statistical differences in cholesterol levels among the three fish species in July and January. Conjugated linoleic acid contents were significantly higher in January in B. plebejus escherichi and C. capoeta capoeta. Of the three species tested, the extreme temperate and cold conditions affected B. plebejus escherichi the most.

  12. Longitudinal quantile regression in the presence of informative dropout through longitudinal-survival joint modeling.

    PubMed

    Farcomeni, Alessio; Viviani, Sara

    2015-03-30

    We propose a joint model for a time-to-event outcome and a quantile of a continuous response repeatedly measured over time. The quantile and survival processes are associated via shared latent and manifest variables. Our joint model provides a flexible approach to handle informative dropout in quantile regression. A Monte Carlo expectation maximization strategy based on importance sampling is proposed, which is directly applicable under any distributional assumption for the longitudinal outcome and random effects. We consider both parametric and nonparametric assumptions for the baseline hazard. We illustrate through a simulation study and an application to an original data set about dilated cardiomyopathies.

  13. Asymmetric impact of rainfall on India's food grain production: evidence from quantile autoregressive distributed lag model

    NASA Astrophysics Data System (ADS)

    Pal, Debdatta; Mitra, Subrata Kumar

    2016-10-01

    This study used a quantile autoregressive distributed lag (QARDL) model to capture asymmetric impact of rainfall on food production in India. It was found that the coefficient corresponding to the rainfall in the QARDL increased till the 75th quantile and started decreasing thereafter, though it remained in the positive territory. Another interesting finding is that at the 90th quantile and above the coefficients of rainfall though remained positive was not statistically significant and therefore, the benefit of high rainfall on crop production was not conclusive. However, the impact of other determinants, such as fertilizer and pesticide consumption, is quite uniform over the whole range of the distribution of food grain production.

  14. Studies of nuclei under the extreme conditions of density, temperature, isospin asymmetry and the phase diagram of hadronic matter

    SciTech Connect

    Mekjian, Aram

    2016-10-18

    The main emphasis of the entire project is on issues having to do with medium energy and ultra-relativistic energy and heavy ion collisions. A major goal of both theory and experiment is to study properties of hot dense nuclear matter under various extreme conditions and to map out the phase diagram in density or chemical potential and temperature. My studies in medium energy nuclear collisions focused on the liquid-gas phase transition and cluster yields from such transitions. Here I developed both the statistical model of nuclear multi-fragmentation and also a mean field theory.

  15. Role of the tissue free amino acids in adaptation of medicinal leeches Hirudo medicinalis L., 1758 to extreme climatic conditions.

    PubMed

    Chernaya, L V; Kovalchuk, L A; Nokhrina, E S

    2016-01-01

    The first comparison of the spectra of free amino acids in tissues of the medicinal leeches H. medicinalis from different climatic and geographical Eurasian areas has been performed. Adaptation of H. medicinalis to extreme climatic conditions occurs via intensification of the amino acid metabolism resulting from a significant increase in the content of essential amino acids. Accumulation of arginine, histidine, and lysine (3.6-, 3.9-, and 2.0-fold increases, respectively) has proved to play a special protective role in adaptation of H. medicinalis to the low positive temperatures.

  16. Extreme Changes in Stream Geomorphic Conditions induced by Fluvial Scour in Bridges

    NASA Astrophysics Data System (ADS)

    Özcan, O.; Ozcan, O.

    2016-12-01

    The numerous complexities associated with bridge scour have caused scour to be one of the most active topics of stream geomorphic research. The assessment of local scouring mechanism around bridge piers provides information for decision-making regarding the pile footing design, predicting the safety of bridges under critical scoured conditions, and as a result, may help prevent unnecessary loses. In the study, bridge design plans and HEC-RAS modeling were used for the assessment of changes in stream geomorphic conditions. The derived fluvial scour depths were compared with the field measurements and the empirical formula which is based on stream flow discharge rate, streambed condition and shape of river. Preliminary results revealed that bridge damage resulting from the flood event in 2003 induced substantial scour around bridge piles. Afterwards, significant stream bed change was observed under the influence of fluvial scour in another flood occurred in 2009. Consequently, geomorphic conditions of the stream bed should be considered in the structural design of the bridges.

  17. Extreme temperatures increase the deleterious consequences of inbreeding under laboratory and semi-natural conditions.

    PubMed

    Kristensen, Torsten N; Barker, J Stuart F; Pedersen, Kamilla S; Loeschcke, Volker

    2008-09-07

    The majority of experimental studies of the effects of population bottlenecks on fitness are performed under laboratory conditions, which do not account for the environmental complexity that populations face in nature. In this study, we test inbreeding depression in multiple replicates of inbred when compared with non-inbred lines of Drosophila melanogaster under different temperature conditions. Egg-to-adult viability, developmental time and sex ratio of emerging adults are studied under low, intermediate and high temperatures under laboratory as well as semi-natural conditions. The results show inbreeding depression for egg-to-adult viability. The level of inbreeding depression is highly dependent on test temperature and is observed only at low and high temperatures. Inbreeding did not affect the developmental time or the sex ratio of emerging adults. However, temperature affected the sex ratio with more females relative to males emerging at low temperatures, suggesting that selection against males in pre-adult life stages is stronger at low temperatures. The coefficient of variation (CV) of egg-to-adult viability within and among lines is higher for inbred flies and generally increases at stressful temperatures. Our results contribute to knowledge on the environmental dependency of inbreeding under different environmental conditions and emphasize that climate change may impact negatively on fitness through synergistic interactions with the genotype.

  18. Phase Transformation of U3O8 and Enhanced Structural Stability at Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Fuxiang; Lang, Maik; Ewing, Rodney

    2013-06-01

    A powder sample of β-U3O8 was pressurized at room temperature up to 37.5 GPa with a symmetric diamond anvil cell. XRD patterns clearly indicated that a phase transition occurred between 3-11 GPa. The high-pressure phase is a fluorite-like structure. The fluorite-like structure is stable up to 37.5 GPa. The high-pressure phase was then laser heated to over 1700 K in the diamond anvil cell at high pressure conditions. No phase transition was found at high pressure/ temperature conditions, and the fluorite-like structure of U3O8 is even fully quenchable. The lattice parameter of the fluorite-like high-pressure phase is 5.425 Å at ambient conditions, which is smaller than that of the stoichiometric UO2. Previous experiments have shown that the stoichiometric uranium dioxide (UO2) is not stable at high pressure conditions and starts to transform to a cotunnite structure at ~30 GPa. When heating the sample at high pressure, the critical transtion pressure is greatly reduced. However, the fluorite-like high-pressure phase of U3O8 is very stable at high pressure/high temperature conditions. The enhanced phase stability is believed to be related to the presence of extra oxygen (or U vacancies) in the structure. This work was supported by Materials Science of Actinides, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0001089.

  19. Penetration Depth Measurements Using a Tunnel Diode Oscillator in Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Agosta, Charles C.

    2004-03-01

    The tunnel diode oscillator (TDO) has been used as a tool in condensed matter physics for over 30 years. We will discuss the application of the TDO to measure rf penetration depth in small metallic and superconducting samples in the range of 10 -1500 MHz. Our technique involves placing a sample in or on the inductor of a self-resonant tank circuit powered by a tunnel diode, and measuring the impedance of the sample by recording the frequency and amplitude shift as a function of magnetic field or temperature. This technique is very sensitive to the properties of the electrons in a sample, does not require contacts on a sample, can be used for arbitrarily small samples, is very compatible with pulsed magnetic fields, and works well in pressure cells. We will begin by giving a brief history of the TDO in condensed matter physics. We will describe the electronic theory of the TDO showing the important parameters necessary to keep the circuit stable and oscillating in different venues such as very low temperatures and pulsed magnetic fields. We will also describe some of the trade offs between stability and sensitivity in these extreme environments. We will then discuss how to interpret the data produced by the TDO, concentrating on the description of rf penetration in metallic and type II superconducting samples. Finally, as examples of the power of this TDO method, we will show Fermi surface measurements, type II superconducting phase diagrams, including details of the vortex system, and very recent results showing evidence of an inhomogeneous superconducting state. Support for this project has come from the NHMFL and the NSF

  20. Transformation and accumulation of PAH and bound residues in soil under extreme conditions - a risk assessment approach

    NASA Astrophysics Data System (ADS)

    Eschenbach, Annette

    2010-05-01

    The degradation of PAH in contaminated soil does not proceed completely in the majority of cases. However microorganisms which are able to degrade PAH are present in PAH-contaminated soils normally. A total degradation of PAH in contaminated soils is often limited by a lack of bioavailability, which results from a lack of mass transfer. The analytical depletion of contaminants in soil is not only based on degradation processes but also on a fixation or immobilization of the xenobiotic substances as stronger adsorbed to or bound residues in the soil matrix. These bound residues were verified by using 14C-labelled PAH in different soil samples. To evaluate the long term fate of theses PAH-residues the stability and transformation of 14C-labelled non-extractable PAH-residues was investigated in detail under different extreme ecological and climate conditions such as biological stress, freezing and thawing cycles, and chemical worst case conditions. The transformation and remobilization of non-extractable PAH-residues was observed in long-time experiments and was very limited in general (Eschenbach et al. 2001). Only small amounts of non extractable residues were transformed and converted to CO2 and thereby detoxified. However the treatment with a complexing agent led to an increase of extractable 14C-activity. In a further set of experiments the long term risk of a groundwater contamination was assessed. Therefore the elution rate of 14C-PAH was investigated by a routinely usable column test system. It was found that the PAH elution was not solely controlled by desorption processes. The extractable PAH concentrations and elution rates were affected by the mineralization and formation of bound residues as well. For the assessment of the maximum PAH release rate the soil material was treated by extreme and worst case conditions as well. The impact of the elution of bidestillated water, of repeated freeze-thaw cycles and a simulation of acidic rain was investigated. The

  1. Growth curves of preschool children in the northeast of iran: a population based study using quantile regression approach.

    PubMed

    Payande, Abolfazl; Tabesh, Hamed; Shakeri, Mohammad Taghi; Saki, Azadeh; Safarian, Mohammad

    2013-01-14

    Growth charts are widely used to assess children's growth status and can provide a trajectory of growth during early important months of life. The objectives of this study are going to construct growth charts and normal values of weight-for-age for children aged 0 to 5 years using a powerful and applicable methodology. The results compare with the World Health Organization (WHO) references and semi-parametric LMS method of Cole and Green. A total of 70737 apparently healthy boys and girls aged 0 to 5 years were recruited in July 2004 for 20 days from those attending community clinics for routine health checks as a part of a national survey. Anthropometric measurements were done by trained health staff using WHO methodology. The nonparametric quantile regression method obtained by local constant kernel estimation of conditional quantiles curves using for estimation of curves and normal values. The weight-for-age growth curves for boys and girls aged from 0 to 5 years were derived utilizing a population of children living in the northeast of Iran. The results were similar to the ones obtained by the semi-parametric LMS method in the same data. Among all age groups from 0 to 5 years, the median values of children's weight living in the northeast of Iran were lower than the corresponding values in WHO reference data. The weight curves of boys were higher than those of girls in all age groups. The differences between growth patterns of children living in the northeast of Iran versus international ones necessitate using local and regional growth charts. International normal values may not properly recognize the populations at risk for growth problems in Iranian children. Quantile regression (QR) as a flexible method which doesn't require restricted assumptions, proposed for estimation reference curves and normal values.

  2. Stability of fluorite-type La2Ce2O7 under extreme conditions

    DOE PAGES

    Zhang, F. X.; Tracy, C. L.; Lang, M.; ...

    2016-03-03

    Here, the structural stability of fluorite-type La2Ce2O7 was studied at pressure up to ~40 GPa and under hydrothermal conditions (~1 GPa, 350 °C), respectively, using synchrotron x-ray diffraction (XRD) and Raman scattering measurements. XRD measurements indicated that fluorite-type La2Ce2O7 is not stable at pressures greater than 22.6 GPa and slowly transforms to a high-pressure phase. The high-pressure phase is not stable and changes back to the fluorite-type structure when pressure is released. The La2Ce2O7 fluorite is also not stable under hydrothermal conditions and begins to react with water at 200~250 °C. Both Raman and XRD results suggest that lanthanum hydroxidemore » La(OH)3 and La3+-doped CeO2 fluorite are the dominant products after hydrothermal treatment.« less

  3. Transport properties of hydrogen-helium mixtures at extreme density and temperature conditions.

    PubMed

    Li, Dafang; Wang, Cong; Kang, Wei; Yan, Jun; Zhang, Ping

    2015-10-01

    We perform a systematic study of hydrogen-helium mixtures using quantum molecular dynamics (QMD) with a focus on the equations of state and structural and transport properties such as electrical conductivity, diffusion, and viscosity at conditions of giant planet interiors of 0.2∼2.3 g/cm(3) and 1000∼80,000 K for a typical helium mass fraction of 0.245. The H-He separation is found at low temperatures by analyzing the trajectories and pair distribution functions. We show that the diffusion coefficients exhibit transitions from kinetics- to potential-, and then to demixing-dominated regimes. In addition, we identify the discontinuity feature of optical absorption of a H-He mixture at low density and temperature conditions, which results from the change from an intraband to an interband transition. The Stokes-Einstein relation between the diffusion and viscosity coefficients is also discussed.

  4. Extreme Hydrothermal Conditions Near an Active Geological Fault, DFDP-2B Borehole, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Sutherland, R.; Townend, J.; Toy, V.; Allen, M.; Baratin, L. M.; Barth, N. C.; Beacroft, L.; Benson, A.; Boese, C. M.; Boles, A.; Boulton, C. J.; Capova, L.; Carpenter, B. M.; Celerier, B. P.; Chamberlain, C. J.; Conze, R.; Cooper, A.; Coussens, J.; Coutts, A.; Cox, S.; Craw, L.; Doan, M. L.; Eccles, J. D.; Faulkner, D.; Grieve, J.; Grochowski, J.; Gulley, A.; Henry, G.; Howarth, J. D.; Jacobs, K. M.; Jeppson, T.; Kato, N.; Keys, S.; Kirilova, M.; Kometani, Y.; Lukács, A.; Langridge, R.; Lin, W.; Little, T.; Mallyon, D.; Mariani, E.; Marx, R.; Massiot, C.; Mathewson, L.; Melosh, B.; Menzies, C. D.; Moore, J.; Morales, L. F. G.; Morgan, C.; Mori, H.; Niemeijer, A. R.; Nishikawa, O.; Nitsch, O.; Paris Cavailhes, J.; Pooley, B.; Prior, D. J.; Pyne, A.; Sauer, K. M.; Savage, M. K.; Schleicher, A.; Schmitt, D. R.; Shigematsu, N.; Taylor-Offord, S.; Tobin, H. J.; Upton, P.; Valdez, R. D.; Weaver, K.; Wiersberg, T.; Williams, J. N.; Yeo, S.; Zimmer, M.; Broderick, N.

    2015-12-01

    The DFDP-2B borehole sampled rocks above and within the upper part of the Alpine Fault, New Zealand, to a depth of 893 m in late 2014. The experiment was the first to drill a major geological fault zone that is active and late in its earthquake cycle. We determined ambient fluid pressures 8-10% above hydrostatic and a geothermal gradient of 130-150 °C/km in rocks above the fault. These unusual ambient conditions can be explained by a combination of: rock advection that transports heat from depth by uplift and oblique slip on the fault; and fluid advection through fractured rock, driven by topographic forcing, which concentrates heat and causes fluid over-pressure in the valley. Highly-anomalous ambient conditions can exist in the vicinity of active faults, and earthquake and mineralization processes occur within these zones.

  5. Genome sequence analysis of Pseudomonas extremaustralis provides new insights into environmental adaptability and extreme conditions resistance.

    PubMed

    Raiger Iustman, Laura J; Tribelli, Paula M; Ibarra, José G; Catone, Mariela V; Solar Venero, Esmeralda C; López, Nancy I

    2015-01-01

    The genome of the Antarctic bacterium Pseudomonas extremaustralis was analyzed searching for genes involved in environmental adaptability focusing on anaerobic metabolism, osmoregulation, cold adaptation, exopolysaccharide production and degradation of complex compounds. Experimental evidences demonstrated the functionality of several of these pathways, including arginine and pyruvate fermentation, alginate production and growth under cold conditions. Phylogenetic analysis along with genomic island prediction allowed the detection of genes with probable foreign origin such as those coding for acetate kinase, osmotic resistance and colanic acid biosynthesis. These findings suggest that in P. extremaustralis the horizontal transfer events and/or gene redundancy could play a key role in the survival under unfavorable conditions. Comparative genome analysis of these traits in other representative Pseudomonas species highlighted several similarities and differences with this extremophile bacterium.

  6. Taking It to Extremes - Powder Diffraction Under Non-Ambient Conditions

    NASA Astrophysics Data System (ADS)

    Millar, David I. A.; Pulham, Colin R.

    Structural studies of materials under elevated pressures provide a fascinating insight into the physical and chemical behaviour of matter under the wide range of conditions experienced throughout the Universe. Both x-ray and neutron powder diffraction techniques play a crucial role in structural studies and are therefore at the forefront of high-pressure research. These notes provide a short introduction to the principles and experimental practice of high-pressure powder diffraction techniques.

  7. Novel portable press for synchrotron time-resolved 3-D micro-imagining under extreme conditions

    SciTech Connect

    Philippe, J.; Le Godec, Y. Bergame, F.; Morand, M.; Mezouar, M.; Bauchau, S.; Alvarez-Murga, M.; Perrillat, J. P.; Bromiley, G.; Berg, M.; King, A.; Guignot, N.; Itié, J. P.; Atwood, Robert

    2016-07-27

    Here we present the instrumental development to extend the synchrotron X-ray microtomography techniques to in situ studies under static compression (HP) or shear stress or the both conditions at high temperatures (HT). To achieve this, a new rotating tomography Paris-Edinburgh cell (rotoPEc) has been developed. This ultra-compact portable device, easily and successfully adapted to various multi-modal synchrotron experimental set-up at ESRF, SOLEIL and DIAMOND is explained in detail.

  8. EFFECTS OF EXTREME AND UNUSUAL CONDITIONS ON LANA ALLOYS: INTERIM REPORT, FY14 (U)

    SciTech Connect

    Shanahan, Kirk L.

    2014-04-25

    The TTP proposed research aimed at determining: a) the rate at which these changes occurred and the effect of initial conditions, especially in the early phases of Hydrogen Heat Treatment (HHT), b) whether or not different LANA alloys would show similar effects, and c) whether common contaminants/poisons impacted LANA alloy hydride chemistry similarly to what had been found for Pd and Pd-alloy hydride chemistry.

  9. MECHANICAL STRENGTH RESPONSES OF POLED LEAD ZIRCONATE TITANATE UNDER EXTREME ELECTRIC FIELD AND VARIOUS TEMPERATURE CONDITIONS

    SciTech Connect

    Wang, Hong; Matsunaga, Tadashi; Zhang, Kewei; Lin, Hua-Tay; Wereszczak, Andrew A

    2016-01-01

    PZT (lead zirconate titanate), particularly PZT-5A, is used in a variety of critical actuation and sensing systems because of its high Curie temperature and large piezoelectric coefficients. However, PZT is susceptible to mechanical failure. The evaluation of the mechanical strength of the material under the target working conditions is very important. This study presents part of the recent experimental developments in mechanical testing and evaluation of PZT materials at Oak Ridge National Laboratory. Ball-on-ring and four-point bending testing setups were used, with modifications made to account for testing requirements from high-level electric field and elevated temperature. The poled PZT-5A or equivalent material was tested under various specimen and testing conditions. The parameters of the distribution of strengths (characteristic strength and Weibull modulus) are discussed in relation to the testing conditions. Fractographic results based on scanning electron microscopy are also presented and discussed. The related data can serve as input for the design of piezoceramic devices, not only those used in energy systems like fuel injectors in heavy-duty diesel engines, but also those used in structural health monitoring, energy harvesting, and other critical systems in aerospace and civil engineering.

  10. Dielectric properties of water under extreme conditions and transport of carbonates in the deep Earth.

    PubMed

    Pan, Ding; Spanu, Leonardo; Harrison, Brandon; Sverjensky, Dimitri A; Galli, Giulia

    2013-04-23

    Water is a major component of fluids in the Earth's mantle, where its properties are substantially different from those at ambient conditions. At the pressures and temperatures of the mantle, experiments on aqueous fluids are challenging, and several fundamental properties of water are poorly known; e.g., its dielectric constant has not been measured. This lack of knowledge of water dielectric properties greatly limits our ability to model water-rock interactions and, in general, our understanding of aqueous fluids below the Earth's crust. Using ab initio molecular dynamics, we computed the dielectric constant of water under the conditions of the Earth's upper mantle, and we predicted the solubility products of carbonate minerals. We found that MgCO3 (magnesite)--insoluble in water under ambient conditions--becomes at least slightly soluble at the bottom of the upper mantle, suggesting that water may transport significant quantities of oxidized carbon. Our results suggest that aqueous carbonates could leave the subducting lithosphere during dehydration reactions and could be injected into the overlying lithosphere. The Earth's deep carbon could possibly be recycled through aqueous transport on a large scale through subduction zones.

  11. Hyper-dry conditions provide new insights into the cause of extreme floods after wildfire

    USGS Publications Warehouse

    Moody, John A.; Ebel, Brian A.

    2012-01-01

    A catastrophic wildfire in the foothills of the Rocky Mountains near Boulder, Colorado provided a unique opportunity to investigate soil conditions immediately after a wildfire and before alteration by rainfall. Measurements of near-surface (θ; and matric suction, ψ), rainfall, and wind velocity were started 8 days after the wildfire began. These measurements established that hyper-dryconditions (θ 3 cm-3; ψ > ~ 3 x 105 cm) existed and provided an in-situ retention curve for these conditions. These conditions exacerbate the effects of water repellency (natural and fire-induced) and limit the effectiveness of capillarity and gravity driven infiltration into fire-affected soils. The important consequence is that given hyper-dryconditions, the critical rewetting process before the first rain is restricted to the diffusion–adsorption of water-vapor. This process typically has a time scale of days to weeks (especially when the hydrologic effects of the ash layer are included) that is longer than the typical time scale (minutes to hours) of some rainstorms, such that under hyper-dryconditions essentially no rain infiltrates. The existence of hyper-dryconditions provides insight into why, frequently during the first rain storm after a wildfire, nearly all rainfall becomes runoff causing extremefloods and debris flows.

  12. Extreme Hypoxic Conditions Induce Selective Molecular Responses and Metabolic Reset in Detached Apple Fruit

    PubMed Central

    Cukrov, Dubravka; Zermiani, Monica; Brizzolara, Stefano; Cestaro, Alessandro; Licausi, Francesco; Luchinat, Claudio; Santucci, Claudio; Tenori, Leonardo; Van Veen, Hans; Zuccolo, Andrea; Ruperti, Benedetto; Tonutti, Pietro

    2016-01-01

    The ripening physiology of detached fruit is altered by low oxygen conditions with profound effects on quality parameters. To study hypoxia-related processes and regulatory mechanisms, apple (Malus domestica, cv Granny Smith) fruit, harvested at commercial ripening, were kept at 1°C under normoxic (control) and hypoxic (0.4 and 0.8 kPa oxygen) conditions for up to 60 days. NMR analyses of cortex tissue identified eight metabolites showing significantly different accumulations between samples, with ethanol and alanine displaying the most pronounced difference between hypoxic and normoxic treatments. A rapid up-regulation of alcohol dehydrogenase and pyruvate-related metabolism (lactate dehydrogenase, pyruvate decarboxylase, alanine aminotransferase) gene expression was detected under both hypoxic conditions with a more pronounced effect induced by the lowest (0.4 kPa) oxygen concentration. Both hypoxic conditions negatively affected ACC synthase and ACC oxidase transcript accumulation. Analysis of RNA-seq data of samples collected after 24 days of hypoxic treatment identified more than 1000 genes differentially expressed when comparing 0.4 vs. 0.8 kPa oxygen concentration samples. Genes involved in cell-wall, minor and major CHO, amino acid and secondary metabolisms, fermentation and glycolysis as well as genes involved in transport, defense responses, and oxidation-reduction appeared to be selectively affected by treatments. The lowest oxygen concentration induced a higher expression of transcription factors belonging to AUX/IAA, WRKY, HB, Zinc-finger families, while MADS box family genes were more expressed when apples were kept under 0.8 kPa oxygen. Out of the eight group VII ERF members present in apple genome, two genes showed a rapid up-regulation under hypoxia, and western blot analysis showed that apple MdRAP2.12 proteins were differentially accumulated in normoxic and hypoxic samples, with the highest level reached under 0.4 kPa oxygen. These data suggest

  13. Extreme Hypoxic Conditions Induce Selective Molecular Responses and Metabolic Reset in Detached Apple Fruit.

    PubMed

    Cukrov, Dubravka; Zermiani, Monica; Brizzolara, Stefano; Cestaro, Alessandro; Licausi, Francesco; Luchinat, Claudio; Santucci, Claudio; Tenori, Leonardo; Van Veen, Hans; Zuccolo, Andrea; Ruperti, Benedetto; Tonutti, Pietro

    2016-01-01

    The ripening physiology of detached fruit is altered by low oxygen conditions with profound effects on quality parameters. To study hypoxia-related processes and regulatory mechanisms, apple (Malus domestica, cv Granny Smith) fruit, harvested at commercial ripening, were kept at 1°C under normoxic (control) and hypoxic (0.4 and 0.8 kPa oxygen) conditions for up to 60 days. NMR analyses of cortex tissue identified eight metabolites showing significantly different accumulations between samples, with ethanol and alanine displaying the most pronounced difference between hypoxic and normoxic treatments. A rapid up-regulation of alcohol dehydrogenase and pyruvate-related metabolism (lactate dehydrogenase, pyruvate decarboxylase, alanine aminotransferase) gene expression was detected under both hypoxic conditions with a more pronounced effect induced by the lowest (0.4 kPa) oxygen concentration. Both hypoxic conditions negatively affected ACC synthase and ACC oxidase transcript accumulation. Analysis of RNA-seq data of samples collected after 24 days of hypoxic treatment identified more than 1000 genes differentially expressed when comparing 0.4 vs. 0.8 kPa oxygen concentration samples. Genes involved in cell-wall, minor and major CHO, amino acid and secondary metabolisms, fermentation and glycolysis as well as genes involved in transport, defense responses, and oxidation-reduction appeared to be selectively affected by treatments. The lowest oxygen concentration induced a higher expression of transcription factors belonging to AUX/IAA, WRKY, HB, Zinc-finger families, while MADS box family genes were more expressed when apples were kept under 0.8 kPa oxygen. Out of the eight group VII ERF members present in apple genome, two genes showed a rapid up-regulation under hypoxia, and western blot analysis showed that apple MdRAP2.12 proteins were differentially accumulated in normoxic and hypoxic samples, with the highest level reached under 0.4 kPa oxygen. These data suggest

  14. Extreme climatic conditions and health service utilisation across rural and metropolitan New South Wales

    NASA Astrophysics Data System (ADS)

    Jegasothy, Edward; McGuire, Rhydwyn; Nairn, John; Fawcett, Robert; Scalley, Benjamin

    2017-03-01

    Periods of successive extreme heat and cold temperature have major effects on human health and increase rates of health service utilisation. The severity of these events varies between geographic locations and populations. This study aimed to estimate the effects of heat waves and cold waves on health service utilisation across urban, regional and remote areas in New South Wales (NSW), Australia, during the 10-year study period 2005-2015. We divided the state into three regions and used 24 over-dispersed or zero-inflated Poisson time-series regression models to estimate the effect of heat waves and cold waves, of three levels of severity, on the rates of ambulance call-outs, emergency department (ED) presentations and mortality. We defined heat waves and cold waves using excess heat factor (EHF) and excess cold factor (ECF) metrics, respectively. Heat waves generally resulted in increased rates of ambulance call-outs, ED presentations and mortality across the three regions and the entire state. For all of NSW, very intense heat waves resulted in an increase of 10.8% (95% confidence interval (CI) 4.5, 17.4%) in mortality, 3.4% (95% CI 0.8, 7.8%) in ED presentations and 10.9% (95% CI 7.7, 14.2%) in ambulance call-outs. Cold waves were shown to have significant effects on ED presentations (9.3% increase for intense events, 95% CI 8.0-10.6%) and mortality (8.8% increase for intense events, 95% CI 2.1-15.9%) in outer regional and remote areas. There was little evidence for an effect from cold waves on health service utilisation in major cities and inner regional areas. Heat waves have a large impact on health service utilisation in NSW in both urban and rural settings. Cold waves also have significant effects in outer regional and remote areas. EHF is a good predictor of health service utilisation for heat waves, although service needs may differ between urban and rural areas.

  15. Role of the Atlantic Multidecadal Variability on extreme climate conditions over North America

    NASA Astrophysics Data System (ADS)

    Ruprich-Robert, Yohan; Delworth, Thomas; Msadek, Rym; Castruccio, Frederic; Yeager, Stephen; Danabasoglu, Gokhan

    2017-04-01

    The Atlantic Multidecadal Variability (AMV) is associated with marked modulations of climate anomalies observed over many areas of the globe like droughts, decline in sea ice or changes in the atmospheric circulation. However, the shortness of the historical observations compared to the AMV period ( 60-80yr) makes it difficult to show that the AMV is a direct driver of these variations. To isolate the AMV climate response, we use a suite of global coupled models from GFDL and NCAR, in which the North Atlantic sea surface temperatures are restored to the observed AMV pattern, while the other ocean basins are left fully coupled. In order to explore and robustly isolate the AMV impacts on extreme events, we use large ensemble simulations (between 30 and 100 members depending on the model) that are integrated for 10 years. We investigate the importance of model resolution by analyzing GFDL models that vary in their atmospheric resolution and we assess the robustness of the results by comparing them to similar experiments performed with the NCAR coupled model. Further, we investigate the influence of model surface temperature biases on the simulated AMV teleconnections using a flux-adjusted experiment based on a model configuration that corrects for momentum, enthalpy and freshwater fluxes. We focus in this presentation on the impact of the AMV on the occurrence of the North American heat waves. We find that the AMV modulates by about 30% the occurrence of heat waves over North Mexico and the South-West of USA, with more heat waves during a warm phase of the AMV. The main reason for such an increase is that, during a warm AMV phase, the anomalously warm sea surface temperature leads to an increase of the atmospheric convection over the tropical Atlantic, as well as to a an anomalous downward motion over North America. This atmospheric response to AMV inhibits the precipitation over there and drives a deficit of soil moisture. In the summer, the latent heat of

  16. Extreme climatic conditions and health service utilisation across rural and metropolitan New South Wales.

    PubMed

    Jegasothy, Edward; McGuire, Rhydwyn; Nairn, John; Fawcett, Robert; Scalley, Benjamin

    2017-03-20

    Periods of successive extreme heat and cold temperature have major effects on human health and increase rates of health service utilisation. The severity of these events varies between geographic locations and populations. This study aimed to estimate the effects of heat waves and cold waves on health service utilisation across urban, regional and remote areas in New South Wales (NSW), Australia, during the 10-year study period 2005-2015. We divided the state into three regions and used 24 over-dispersed or zero-inflated Poisson time-series regression models to estimate the effect of heat waves and cold waves, of three levels of severity, on the rates of ambulance call-outs, emergency department (ED) presentations and mortality. We defined heat waves and cold waves using excess heat factor (EHF) and excess cold factor (ECF) metrics, respectively. Heat waves generally resulted in increased rates of ambulance call-outs, ED presentations and mortality across the three regions and the entire state. For all of NSW, very intense heat waves resulted in an increase of 10.8% (95% confidence interval (CI) 4.5, 17.4%) in mortality, 3.4% (95% CI 0.8, 7.8%) in ED presentations and 10.9% (95% CI 7.7, 14.2%) in ambulance call-outs. Cold waves were shown to have significant effects on ED presentations (9.3% increase for intense events, 95% CI 8.0-10.6%) and mortality (8.8% increase for intense events, 95% CI 2.1-15.9%) in outer regional and remote areas. There was little evidence for an effect from cold waves on health service utilisation in major cities and inner regional areas. Heat waves have a large impact on health service utilisation in NSW in both urban and rural settings. Cold waves also have significant effects in outer regional and remote areas. EHF is a good predictor of health service utilisation for heat waves, although service needs may differ between urban and rural areas.

  17. Extreme climatic conditions and health service utilisation across rural and metropolitan New South Wales

    NASA Astrophysics Data System (ADS)

    Jegasothy, Edward; McGuire, Rhydwyn; Nairn, John; Fawcett, Robert; Scalley, Benjamin

    2017-08-01

    Periods of successive extreme heat and cold temperature have major effects on human health and increase rates of health service utilisation. The severity of these events varies between geographic locations and populations. This study aimed to estimate the effects of heat waves and cold waves on health service utilisation across urban, regional and remote areas in New South Wales (NSW), Australia, during the 10-year study period 2005-2015. We divided the state into three regions and used 24 over-dispersed or zero-inflated Poisson time-series regression models to estimate the effect of heat waves and cold waves, of three levels of severity, on the rates of ambulance call-outs, emergency department (ED) presentations and mortality. We defined heat waves and cold waves using excess heat factor (EHF) and excess cold factor (ECF) metrics, respectively. Heat waves generally resulted in increased rates of ambulance call-outs, ED presentations and mortality across the three regions and the entire state. For all of NSW, very intense heat waves resulted in an increase of 10.8% (95% confidence interval (CI) 4.5, 17.4%) in mortality, 3.4% (95% CI 0.8, 7.8%) in ED presentations and 10.9% (95% CI 7.7, 14.2%) in ambulance call-outs. Cold waves were shown to have significant effects on ED presentations (9.3% increase for intense events, 95% CI 8.0-10.6%) and mortality (8.8% increase for intense events, 95% CI 2.1-15.9%) in outer regional and remote areas. There was little evidence for an effect from cold waves on health service utilisation in major cities and inner regional areas. Heat waves have a large impact on health service utilisation in NSW in both urban and rural settings. Cold waves also have significant effects in outer regional and remote areas. EHF is a good predictor of health service utilisation for heat waves, although service needs may differ between urban and rural areas.

  18. Explosive Chemistry: Simulating the Chemistry of Energetic Materials at Extreme Conditions

    SciTech Connect

    Reed, E J; Manaa, M R; Fried, L E

    2003-11-18

    In the brief instant of a high-explosive detonation, the shock wave produces a pressure 500,000 times that of the Earth's atmosphere, the detonation wave travels as fast as 10 kilometers per second, and internal temperatures soar up to 5,500 Kelvin. As the shock propagates through the energetic material, the rapid heating coupled with compression that results in almost 30% volume reduction, initiate complex chemical reactions. A dense, highly reactive supercritical fluid is established behind the propagating detonation front. Energy release from the exothermic chemical reactions serve in turn to drive and sustain the detonation process until complete reactivity is reached. Several experimental results suggest the existence of strong correlations between the applied mechanical stress and shocks, the local heterogeneity and defects (dislocations, vacancies, cracks, impurities, etc.), and the onset of chemical reactions. The reaction chemistry of energetic materials at high pressure and temperature is, therefore, of considerable importance in understanding processes that these materials experience under impact and detonation conditions. Chemical decomposition models are critical ingredients in order to predict, among other things, the measured times to explosion and the conditions for ignition of hot spots, localized regions of highly concentrated energy associated with defects. To date, chemical kinetic rates of condense-phase energetic materials at detonation conditions are virtually non-existent, and basic questions such as: (a) which bond in a given energetic molecule breaks first, and (b) what type of chemical reactions (unimolecular versus bimolecular, etc.) that dominate early in the decomposition process, are still largely unknown.

  19. Quantification of Cation Sorption to Engineered Barrier Materials Under Extreme Conditions

    SciTech Connect

    Powell, Brian; Schlautman, Mark; Rao, Linfeng; Nitsche, Heino; Gregorich, Kenneth

    2016-02-02

    The objective of this research is to examine mechanisms and thermodynamics of actinide sorption to engineered barrier materials (iron (oxyhydr)oxides and bentonite clay) for nuclear waste repositories under high temperature and high ionic strength conditions using a suite of macroscopic and microscopic techniques which will be coupled with interfacial reaction models. Gaining a mechanistic understanding of interfacial processes governing the sorption/sequestration of actinides at mineral-water interfaces is fundamental for the accurate prediction of actinide behavior in waste repositories. Although macroscale sorption data and various spectroscopic techniques have provided valuable information regarding speciation of actinides at solid-water interfaces, significant knowledge gaps still exist with respect to sorption mechanisms and the ability to quantify sorption, particularly at high temperatures and ionic strengths. This objective is addressed through three major tasks: (1) influence of oxidation state on actinide sorption to iron oxides and clay minerals at elevated temperatures and ionic strengths; (2) calorimetric titrations of actinide-mineral suspensions; (3) evaluation of bentonite performance under repository conditions. The results of the work will include a qualitative conceptual model and a quantitative thermodynamic speciation model describing actinide partitioning to minerals and sediments, which is based upon a mechanistic understanding of specific sorption processes as determined from both micro-scale and macroscale experimental techniques. The speciation model will be a thermodynamic aqueous and surface complexation model of actinide interactions with mineral surfaces that is self-consistent with macroscopic batch sorption data, calorimetric and potentiometric titrations, X-ray absorption Spectroscopy (XAS, mainly Extended X-ray Absorption Fine Structure (EXAFS)), and electron microscopy analyses. The novelty of the proposed work lies largely in

  20. SIPEX 2012: Extreme sea-ice and atmospheric conditions off East Antarctica

    NASA Astrophysics Data System (ADS)

    Heil, P.; Stammerjohn, S.; Reid, P.; Massom, R. A.; Hutchings, J. K.

    2016-09-01

    In 2012, Antarctic sea-ice coverage was marked by weak annual-mean climate anomalies that consisted of opposing anomalies early and late in the year (some setting new records) which were interspersed by near-average conditions for most of the austral autumn and winter. Here, we investigate the ocean-ice-atmosphere system off East Antarctica, prior to and during the Sea Ice Physics and Ecosystems eXperiment [SIPEX] 2012, by exploring relationships between atmospheric and oceanic forcing together with the sea-ice and snow characteristics. During August and September 2012, just prior to SIPEX 2012, atmospheric circulation over the Southern Ocean was near-average, setting up the ocean-ice-atmosphere system for near-average conditions. However, below-average surface pressure and temperature as well as strengthened circumpolar winds prevailed during June and July 2012. This led to a new record (19.48×106 km2) in maximum Antarctic sea-ice extent recorded in late September. In contrast to the weak circum-Antarctic conditions, the East Antarctic sector (including the SIPEX 2012 region) experienced positive sea-ice extent and concentration anomalies during most of 2012, coincident with negative atmospheric pressure and sea-surface temperature anomalies. Heavily deformed sea ice appeared to be associated with intensified wind stress due to increased cyclonicity as well as an increased influx of sea ice from the east. This increased westward ice flux is likely linked to the break-up of nearly 80% of the Mertz Glacier Tongue in 2010, which strongly modified the coastal configuration and hence the width of the westward coastal current. Combined with favourable atmospheric conditions the associated changed coastal configuration allowed more sea ice to remain within the coastal current at the expense of a reduced northward flow in the region around 141°-145°E. In addition a westward propagating positive anomaly of sea-ice extent from the western Ross Sea during austral winter

  1. Electrical conductivity of SiO2 at extreme conditions and planetary dynamos

    PubMed Central

    Scipioni, Roberto; Stixrude, Lars; Desjarlais, Michael P.

    2017-01-01

    Ab intio molecular dynamics simulations show that the electrical conductivity of liquid SiO2 is semimetallic at the conditions of the deep molten mantle of early Earth and super-Earths, raising the possibility of silicate dynamos in these bodies. Whereas the electrical conductivity increases uniformly with increasing temperature, it depends nonmonotonically on compression. At very high pressure, the electrical conductivity decreases on compression, opposite to the behavior of many materials. We show that this behavior is caused by a novel compression mechanism: the development of broken charge ordering, and its influence on the electronic band gap. PMID:28784773

  2. Electrical conductivity of SiO2 at extreme conditions and planetary dynamos.

    PubMed

    Scipioni, Roberto; Stixrude, Lars; Desjarlais, Michael P

    2017-08-22

    Ab intio molecular dynamics simulations show that the electrical conductivity of liquid SiO2 is semimetallic at the conditions of the deep molten mantle of early Earth and super-Earths, raising the possibility of silicate dynamos in these bodies. Whereas the electrical conductivity increases uniformly with increasing temperature, it depends nonmonotonically on compression. At very high pressure, the electrical conductivity decreases on compression, opposite to the behavior of many materials. We show that this behavior is caused by a novel compression mechanism: the development of broken charge ordering, and its influence on the electronic band gap.

  3. Electromyographic Reliability and Analysis of Selected Lower Extremity Muscles During Lateral Step-Up Conditions

    PubMed Central

    Worrell, Teddy W.; Crisp, Elizabeth; LaRosa, Christopher

    1998-01-01

    Objective: To determine 1) the electromyographic (EMG) reliability within and between testing sessions; 2) the effect of sex on the EMG activity of the vastus medialis oblique (VMO), vastus lateralis (VL), hamstring (HS), and gluteus maximus (GM) and VMO:VL ratios during maximal voluntary isometric contraction (MVIC) and lateral step-up (LSU) conditions; and 3) the muscle recruitment and VMO:VL ratios during MVIC and LSU conditions. Design and Setting: Subjects participated in a familiarization session and two testing sessions in which they performed a 20.32-cm (8-in) LSU with and without resistance while the EMG activity was monitored for the VMO, VL, HS, and GM muscles. Subjects: Nineteen subjects performed LSUs holding 25% body weight (Group 25%), and 13 subjects performed LSUs holding 10% body weight (Group 10%). There were 32 subjects total: 19 males and 13 females. Measurements: Statistical analyses included a two-way analysis of variance (ANOVA) to compare sex and testing conditions for percentage of MVIC and VMO:VL ratios; three-way repeated-measures ANOVA to compare muscle, resistance, and session factors for percentage of MVIC; and a two-way repeated-measures ANOVA to compare conditions and session factors for VMO:VL ratios. These analyses were performed for both groups. Results: Reliability results revealed good intrasession and poor intersession intraclass correlation coefficients. No difference existed in muscle recruitment or VMO:VL ratios between males and females for either group. The three-way ANOVA revealed a significant two-way interaction (muscle × resistance) for both groups. Post hoc testing revealed the following EMG recruitment patterns: VMO > HS, GM, VL;VL > HS, GM; HS = GM for both groups. For Group 25%, the two-way ANOVA revealed greater VMO:VL ratios during MVIC for session one than for LSU. Conclusions: Intrasession reliability was higher than intersession reliability, but similar conclusions were reached concerning muscle recruitment

  4. Electrical conductivity of SiO2 at extreme conditions and planetary dynamos

    NASA Astrophysics Data System (ADS)

    Scipioni, Roberto; Stixrude, Lars; Desjarlais, Michael P.

    2017-08-01

    Ab intio molecular dynamics simulations show that the electrical conductivity of liquid SiO2 is semimetallic at the conditions of the deep molten mantle of early Earth and super-Earths, raising the possibility of silicate dynamos in these bodies. Whereas the electrical conductivity increases uniformly with increasing temperature, it depends nonmonotonically on compression. At very high pressure, the electrical conductivity decreases on compression, opposite to the behavior of many materials. We show that this behavior is caused by a novel compression mechanism: the development of broken charge ordering, and its influence on the electronic band gap.

  5. Laboratory measurements of materials in extreme conditions; The use of high energy radiation sources for high pressure studies

    SciTech Connect

    Cauble, R.; Remington, B.A.

    1998-06-01

    High energy lasers can be used to study material conditions that are appropriate fort inertial confinement fusion: that is, materials at high densities, temperatures, and pressures. Pulsed power devices can offer similar opportunities. The National Ignition Facility (NIF) will be a high energy multi-beam laser designed to achieve the thermonuclear ignition of a mm-scale DT-filled target in the laboratory. At the same time, NE will provide the physics community with a unique tool for the study of high energy density matter at states unreachable by any other laboratory technique. Here we describe how these lasers and pulsed power tools can contribute to investigations of high energy density matter in the areas of material properties and equations of state, extend present laboratory shock techniques such as high-speed jets to new regimes, and allow study of extreme conditions found in astrophysical phenomena.

  6. Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions.

    PubMed

    Sánchez-Román, Mónica; Fernández-Remolar, David; Amils, Ricardo; Sánchez-Navas, Antonio; Schmid, Thomas; San Martin-Uriz, Patxi; Rodríguez, Nuria; McKenzie, Judith A; Vasconcelos, Crisogono

    2014-04-23

    Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets.

  7. Helium bubble formation in ultrafine and nanocrystalline tungsten under different extreme conditions

    DOE PAGES

    El-atwani, O.; Hattar, Khalid Mikhiel; Hinks, J. A.; ...

    2014-12-25

    We investigated the effects of helium ion irradiation energy and sample temperature on the performance of grain boundaries as helium sinks in ultrafine grained and nanocrystalline tungsten. Irradiations were performed at displacement and non-displacement energies and at temperatures above and below that required for vacancy migration. Microstructural investigations were performed using Transmission Electron Microscopy (TEM) combined with either in-situ or ex-situ ion irradiation. Under helium irradiation at an energy which does not cause atomic displacements in tungsten (70 eV), regardless of temperature and thus vacancy migration conditions, bubbles were uniformly distributed with no preferential bubble formation on grain boundaries. Moreover,more » at energies that can cause displacements, bubbles were observed to be preferentially formed on the grain boundaries only at high temperatures where vacancy migration occurs. Under these conditions, the decoration of grain boundaries with large facetted bubbles occurred on nanocrystalline grains with dimensions less than 60 nm. Finally, we discuss the importance of vacancy supply and the formation and migration of radiation-induced defects on the performance of grain boundaries as helium sinks and the resulting irradiation tolerance of ultrafine grained and nanocrystalline tungsten to bubble formation.« less

  8. Helium bubble formation in ultrafine and nanocrystalline tungsten under different extreme conditions

    SciTech Connect

    El-atwani, O.; Hattar, Khalid Mikhiel; Hinks, J. A.; Greaves, G.; Harilal, S. S.; Hassanein, A.

    2014-12-25

    We investigated the effects of helium ion irradiation energy and sample temperature on the performance of grain boundaries as helium sinks in ultrafine grained and nanocrystalline tungsten. Irradiations were performed at displacement and non-displacement energies and at temperatures above and below that required for vacancy migration. Microstructural investigations were performed using Transmission Electron Microscopy (TEM) combined with either in-situ or ex-situ ion irradiation. Under helium irradiation at an energy which does not cause atomic displacements in tungsten (70 eV), regardless of temperature and thus vacancy migration conditions, bubbles were uniformly distributed with no preferential bubble formation on grain boundaries. Moreover, at energies that can cause displacements, bubbles were observed to be preferentially formed on the grain boundaries only at high temperatures where vacancy migration occurs. Under these conditions, the decoration of grain boundaries with large facetted bubbles occurred on nanocrystalline grains with dimensions less than 60 nm. Finally, we discuss the importance of vacancy supply and the formation and migration of radiation-induced defects on the performance of grain boundaries as helium sinks and the resulting irradiation tolerance of ultrafine grained and nanocrystalline tungsten to bubble formation.

  9. Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions

    NASA Astrophysics Data System (ADS)

    Sánchez-Román, Mónica; Fernández-Remolar, David; Amils, Ricardo; Sánchez-Navas, Antonio; Schmid, Thomas; Martin-Uriz, Patxi San; Rodríguez, Nuria; McKenzie, Judith A.; Vasconcelos, Crisogono

    2014-04-01

    Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets.

  10. Southern giant Petrel Macronectes giganteus nest attendance patterns under extreme weather conditions.

    PubMed

    Schulz, Uwe Horst; Krüger, Lucas; Petry, Maria Virginia

    2014-08-01

    Differences in nest attendance between genders in seabirds may be related to morphological differences. Southern giant petrel is a dimorphic species with gender-specific foraging behavior. The objective of this study was to investigate sex-related differences in nest attendance during the breeding period of southern giant petrels by presence/absence patterns of both sexes during incubation and compare use of the colony after nest failure. Fourteen birds were tagged with digitally coded radio-transmitters in a colony at Elephant Island, Antarctica, in the beginning of 2009/2010 breeding season. Females were present during 18 periods (min. 3 days, max. 9 days) and males only in five periods (min. 2 days, max. 13 days). The difference in mean number of radio signals per day between females (4330; s.e. 313.5) and males (2691; s.e. 248.6) was highly significant (t = 4.3; d.f. = 199; P < 0.001; Fig. 4 ). As consequence of the severe weather conditions that year, all tagged birds failed to reproduce. After abandonment of the nests, the presence of both genders decreased drastically, although the tagged individuals stayed in the area. Under severe weather conditions female Southern Giant Petrels continue breeding while males abandon the nest earlier.

  11. Dielectric properties of water under extreme conditions and transport of carbonates in the deep Earth

    PubMed Central

    Pan, Ding; Spanu, Leonardo; Harrison, Brandon; Sverjensky, Dimitri A.; Galli, Giulia

    2013-01-01

    Water is a major component of fluids in the Earth’s mantle, where its properties are substantially different from those at ambient conditions. At the pressures and temperatures of the mantle, experiments on aqueous fluids are challenging, and several fundamental properties of water are poorly known; e.g., its dielectric constant has not been measured. This lack of knowledge of water dielectric properties greatly limits our ability to model water–rock interactions and, in general, our understanding of aqueous fluids below the Earth’s crust. Using ab initio molecular dynamics, we computed the dielectric constant of water under the conditions of the Earth’s upper mantle, and we predicted the solubility products of carbonate minerals. We found that MgCO3 (magnesite)—insoluble in water under ambient conditions—becomes at least slightly soluble at the bottom of the upper mantle, suggesting that water may transport significant quantities of oxidized carbon. Our results suggest that aqueous carbonates could leave the subducting lithosphere during dehydration reactions and could be injected into the overlying lithosphere. The Earth’s deep carbon could possibly be recycled through aqueous transport on a large scale through subduction zones. PMID:23513225

  12. Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions

    PubMed Central

    Sánchez-Román, Mónica; Fernández-Remolar, David; Amils, Ricardo; Sánchez-Navas, Antonio; Schmid, Thomas; Martin-Uriz, Patxi San; Rodríguez, Nuria; McKenzie, Judith A.; Vasconcelos, Crisogono

    2014-01-01

    Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets. PMID:24755961

  13. Performance of pressurized metered-dose inhalers at extreme temperature conditions.

    PubMed

    Morin, Chelsea M D; Ivey, James W; Titosky, Jordan T F; Suderman, Jonathan D; Olfert, Jason S; Vehring, Reinhard; Finlay, Warren H

    2014-11-01

    The performance of pressurized metered-dose inhalers (pMDIs) under a variety of temperature conditions was investigated. The effects of both inhaler temperature and ambient temperature were considered. The inhaler temperature ranged from -13.0°C to 41.7°C and the ambient temperature ranged from -12.0°C to 41.7°C. The in vitro lung dose was measured for four widely available pMDIs: Airomir(TM) , QVAR(TM) , Symbicort(®) , and Ventolin(®) . The in vitro lung dose through an Alberta Idealized Throat was measured by gravimetric assay, which was verified by UV spectroscopic assay. A decrease in the in vitro lung dose was observed for all evaluated pMDIs when ambient temperature and device temperature were simultaneously reduced, decreasing on average by 70% at the coldest temperatures, whereas increasing on average by 25% at the elevated temperature condition. In vitro lung dose is strongly dependent on both inhaler temperature and ambient temperature with the tested pMDIs. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  14. Sputtering at Mars: MAVEN observations of precipitating and escaping oxygen during nominal and extreme conditions

    NASA Astrophysics Data System (ADS)

    Curry, Shannon; Luhmann, Janet; Dong, Chuanfei; Ma, Yingjuan; Leblanc, Francois; Modolo, Ronan; Brain, David; Gruesbeck, Jacob; Hara, Takuya; Halekas, Jasper; Dong, Yaxue; Williamson, Hayley N.; Johnson, Robert E.; McFadden, James; Espley, Jared R.; Mitchell, David; Connerney, Jack; Eparvier, Frank; Lillis, Robert J.; Jakosky, Bruce

    2016-10-01

    Sputtering is believed to be one of the dominant escape mechanisms during the early epochs of our solar system when the solar activity and EUV intensities were much higher than the present day. Mars lacks a global dynamo magnetic field, which creates a scenario where the solar wind directly interacts with the upper atmosphere and newly created ions can be picked up and swept away by the background convection electric field. These pick-up ions can directly escape or precipitate back into the atmosphere and induce atmospheric sputtering of neutrals.The MAVEN spacecraft has observed the Mars upper atmosphere, ionosphere, magnetic topology and interactions with the Sun and solar wind during numerous Interplanetary Coronal Mass Ejection (ICME) impacts spanning from March 2015 to June 2016. ICMEs are associated with enhanced solar wind velocities, densities and magnetic field strength, and often drive heavy ion precipitation at much higher rates than during nominal conditions. Thus, ICMEs provide a unique environment for observing sputtering. We will compare MAVEN observations of heavy ion precipitation during nominal conditions as well as during ICMEs. Additionally, we will present global MHD and test particle simulations of the ICMEs in order to calculate sputtering escape rates for oxygen. Finally, we will use the observed and modeled sputtering escape rates to provide an initial estimate of the total sputtered atmospheric escape from Mars over billions of years.

  15. Modulation of Pleurodeles waltl DNA Polymerase mu Expression by Extreme Conditions Encountered during Spaceflight

    PubMed Central

    Baatout, Sarah; Frippiat, Jean-Pol

    2013-01-01

    DNA polymerase µ is involved in DNA repair, V(D)J recombination and likely somatic hypermutation of immunoglobulin genes. Our previous studies demonstrated that spaceflight conditions affect immunoglobulin gene expression and somatic hypermutation frequency. Consequently, we questioned whether Polμ expression could also be affected. To address this question, we characterized Polμ of the Iberian ribbed newt Pleurodeles waltl and exposed embryos of that species to spaceflight conditions or to environmental modifications corresponding to those encountered in the International Space Station. We noted a robust expression of Polμ mRNA during early ontogenesis and in the testis, suggesting that Polμ is involved in genomic stability. Full-length Polμ transcripts are 8–9 times more abundant in P. waltl than in humans and mice, thereby providing an explanation for the somatic hypermutation predilection of G and C bases in amphibians. Polμ transcription decreases after 10 days of development in space and radiation seem primarily involved in this down-regulation. However, space radiation, alone or in combination with a perturbation of the circadian rhythm, did not affect Polμ protein levels and did not induce protein oxidation, showing the limited impact of radiation encountered during a 10-day stay in the International Space Station. PMID:23936065

  16. Synchrotron Radiation and High Pressure: New Light on Materials Under Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Hemley, Russell

    2005-03-01

    Current technological advances now make it possible to perform experiments on materials subjected to static or sustained conditions up to multimegabar pressures (>300 GPa) and from cryogenic temperatures to several thousand degrees (˜0.5 eV range). With these techniques, densities of condensed matter can be increased over an order of magnitude, causing numerous transformations and new physical and chemical phenomena to occur. Growth in this area largely been made possible by accelerating developments in diamond-anvil cell methods coupled with new synchrotron radiation techniques. Significant advances have occurred in x-ray diffraction, spectroscopy, inelastic scattering, radiography, and infrared spectroscopy. With recent developments, structure refinements based on polycrystalline data up to multimegabar pressures have been possible. Single-crystal methods have been extended to megabar pressure, with the prospect of full crystallographic refinements. `Three- dimensional' diffraction data can be collected for determining strength, deformation, and elastic tensors at high P-T conditions. Studies carried out during the past three years provide numerous breakthroughs in high-pressure x-ray spectroscopy and a broad range of inelastic scattering methods. Other experiments have exploited the use of x-ray radiography over a range of pressures. Finally, synchrotron infrared measurements have revealed a wealth of high-pressure phenomena, particularly for molecular systems. Examples to be discussed include investigations of dense hydrogen; transformations in molecular materials; novel ceramics; new types of superconductors, electronic, and magnetic materials; and liquids and amorphous materials.

  17. The impact of extreme weather conditions on the life of settlers in the Central Russia in X - XVI centuries

    NASA Astrophysics Data System (ADS)

    Graves, Irina; Nizovtsev, Viacheslav; Erman, Natalia

    2017-04-01

    A special place in the reconstruction of climate dynamics takes an analysis of extraordinary meteorological phenomena. These extreme weather events in the first place impact the functioning of, the rhythm and dynamics of the landscapes and determine not only the features of economy, but also certain aspects of historical development. In the analysis of primary chronicles and published data, along with the direct climatic characteristics (hot, warm, cold, wet, dry, etc.) a lot of attention was paid to abnormal (extreme) natural phenomena and indirect indications of climate variability (floods, crop failures, hunger years, epidemics, etc.). As a result, tables were compiled reflecting climatic basic characteristics and extremes for each year since 900 BC. X-XI centuries was a period of minor climatic optimum - the climate was warmer and drier than the modern one. In addition to higher temperatures (up to 1-3C above than mordern), during this period there were no severe winters. A small amount of summer rainfall has led to a reduction in the number of small water reservoirs and flooding rivers. This is evidenced by Slavic settlements on floodplains of a number of rivers in the Moscow region. It is in this favorable climatic time the way "from the Vikings to the Greeks" was open. Catastrophic natural events had a minimum repeatability. For example, during the X century the Russian chronicles mentioned 41 extreme event, but for the XIII century - 102. Most of the villages and towns were located on the low floodplain terraces of rivers. The main farmland was concentrated there as well. In the "period of contrasts" (XIII - XIV centuries) there was an increase of intra-seasonal climate variability, humidity and widespread reduction in summer temperatures by 1-2C. The number of extreme weather events increased: cold prolonged winters, long rains in summers, cold weather returns in the early summer, early frosts in late summer - early autumn. Such conditions often

  18. Estimation of predictive hydrologic uncertainty using quantile regression and UNEEC methods and their comparison on contrasting catchments

    NASA Astrophysics Data System (ADS)

    Dogulu, N.; López López, P.; Solomatine, D. P.; Weerts, A. H.; Shrestha, D. L.

    2014-09-01

    In operational hydrology, estimation of predictive uncertainty of hydrological models used for flood modelling is essential for risk based decision making for flood warning and emergency management. In the literature, there exists a variety of methods analyzing and predicting uncertainty. However, case studies comparing performance of these methods, most particularly predictive uncertainty methods, are limited. This paper focuses on two predictive uncertainty methods that differ in their methodological complexity: quantile regression (QR) and UNcertainty Estimation based on local Errors and Clustering (UNEEC), aiming at identifying possible advantages and disadvantages of these methods (both estimating residual uncertainty) based on their comparative performance. We test these two methods on several catchments (from UK) that vary in its hydrological characteristics and models. Special attention is given to the errors for high flow/water level conditions. Furthermore, normality of model residuals is discussed in view of clustering approach employed within the framework of UNEEC method. It is found that basin lag time and forecast lead time have great impact on quantification of uncertainty (in the form of two quantiles) and achievement of normality in model residuals' distribution. In general, uncertainty analysis results from different case studies indicate that both methods give similar results. However, it is also shown that UNEEC method provides better performance than QR for small catchments with changing hydrological dynamics, i.e. rapid response catchments. We recommend that more case studies of catchments from regions of distinct hydrologic behaviour, with diverse climatic conditions, and having various hydrological features be tested.

  19. Analysis of U.S. freight-train derailment severity using zero-truncated negative binomial regression and quantile regression.

    PubMed

    Liu, Xiang; Saat, M Rapik; Qin, Xiao; Barkan, Christopher P L

    2013-10-01

    Derailments are the most common type of freight-train accidents in the United States. Derailments cause damage to infrastructure and rolling stock, disrupt services, and may cause casualties and harm the environment. Accordingly, derailment analysis and prevention has long been a high priority in the rail industry and government. Despite the low probability of a train derailment, the potential for severe consequences justify the need to better understand the factors influencing train derailment severity. In this paper, a zero-truncated negative binomial (ZTNB) regression model is developed to estimate the conditional mean of train derailment severity. Recognizing that the mean is not the only statistic describing data distribution, a quantile regression (QR) model is also developed to estimate derailment severity at different quantiles. The two regression models together provide a better understanding of train derailment severity distribution. Results of this work can be used to estimate train derailment severity under various operational conditions and by different accident causes. This research is intended to provide insights regarding development of cost-efficient train safety policies.

  20. Model Related Estimates of time dependent quantiles of peak flows - case study for selected catchments in Poland

    NASA Astrophysics Data System (ADS)

    Strupczewski, Witold G.; Bogdanowich, Ewa; Debele, Sisay

    2016-04-01

    Under Polish climate conditions the series of Annual Maxima (AM) flows are usually a mixture of peak flows of thaw- and rainfall- originated floods. The northern, lowland regions are dominated by snowmelt floods whilst in mountainous regions the proportion of rainfall floods is predominant. In many stations the majority of AM can be of snowmelt origin, but the greatest peak flows come from rainfall floods or vice versa. In a warming climate, precipitation is less likely to occur as snowfall. A shift from a snow- towards a rain-dominated regime results in a decreasing trend in mean and standard deviations of winter peak flows whilst rainfall floods do not exhibit any trace of non-stationarity. That is why a simple form of trends (i.e. linear trends) are more difficult to identify in AM time-series than in Seasonal Maxima (SM), usually winter season time-series. Hence it is recommended to analyse trends in SM, where a trend in standard deviation strongly influences the time -dependent upper quantiles. The uncertainty associated with the extrapolation of the trend makes it necessary to apply a relationship for trend which has time derivative tending to zero, e.g. we can assume a new climate equilibrium epoch approaching, or a time horizon is limited by the validity of the trend model. For both winter and summer SM time series, at least three distributions functions with trend model in the location, scale and shape parameters are estimated by means of the GAMLSS package using the ML-techniques. The resulting trend estimates in mean and standard deviation are mutually compared to the observed trends. Then, using AIC measures as weights, a multi-model distribution is constructed for each of two seasons separately. Further, assuming a mutual independence of the seasonal maxima, an AM model with time-dependent parameters can be obtained. The use of a multi-model approach can alleviate the effects of different and often contradictory trends obtained by using and identifying

  1. Watch the tail! A story on extreme hourly precipitation

    NASA Astrophysics Data System (ADS)

    Papalexiou, Simon Michael; Foufoula-Georgiou, Efi; AghaKouchack, Amir

    2017-04-01

    The problem of tail identification and estimation in hydro-meteorological variables is in principle difficult due to limited empirical extreme observations, while it becomes even more challenging under the assumption of non-stationary conditions arising from climatic and/or anthropogenic factors. In this study a rigorous analysis of 7,000 stations of hourly precipitation over the United States is performed in order to: (a) identify which major type of tail, i.e., power-type or stretched exponential, describes better extreme hourly precipitation, (b) quantify the tail shape parameter and examine how results are affected by the quantile used to define the tail, and (c) investigate the spatial variation of the tails of hourly precipitation over the U.S. and its relation to Köppen-Geiger climate classification. The findings suggest that stretched exponential tails are more consistent with observations, while the estimated mean shape parameter value equals to 0.55, a value indicating that hourly precipitation extremes are more frequent and larger in magnitude than what popular and commonly used models suggest, e.g., the Gamma distribution. Also, the analysis shows that the power-type shape parameter is affected by the empirical definition of the tail. Finally, it is interestingly to observe that the spatial variation of the shape parameter matches in general the spatial pattern of the Köppen-Geiger climate classification, suggesting that extreme hourly precipitation is strongly related on specific climatic types.

  2. Does the shift to higher capacities for isoprene emission at extreme temperatures in some oak species reflect acclimation to extreme drought and high temperature conditions?

    NASA Astrophysics Data System (ADS)

    Barta, C.; Gramann, J. H.; White, S. L.; Schade, G. W.

    2013-12-01

    Isoprene emission from the vegetation accounts for a substantial fraction of assimilated carbon and is an important biosphere-atmosphere interaction, being a key constraint to the chemical properties of the troposphere. Isoprene synthesis is controlled by isoprene synthase and is connected to photosynthesis through production of precursor metabolites, while subsequent emission is affected by the physical environment and is altered by exposure to environmental stress. An intricate, yet not completely understood balance exists between the impact of isoprene on the atmosphere and the feedback of global change on the eco-physiology of vegetation that defines future emission potentials, affecting to a yet unknown extent future isoprene emissions. To address the nature of these interactions, we set up a field study that characterizes the effects of climate and pollution gradients on carbon assimilation and isoprene emission fluxes of dominant oak tree species in Texas. We followed selected oak species throughout their growth season during the exceptional drought in 2011 and following recovery during 2012 and 2013, by comparing tree response to their growth environment at three selected sites along an urban to rural transect from downtown Houston to the Sam Houston National Forest. As urban areas are warmer, more polluted and often drier than rural regions, they are used in our study as an environment that mimics conditions expected from global climate change. Our results revealed significant differences in the drought stress response of the investigated oak species, Quercus nigra and Q.stellata. The early onset of drought in 2011 affected mostly the urban trees: the assimilation of Q. nigra decreased by 90% below optimum already in the beginning of the season, while only by 35% in the more resistant Q. stellata. The extreme drought uncoupled isoprene emission from photosynthesis: though correlated with photosynthesis, emission rates were less affected, with a maximum

  3. Comparison of wetlands in different hydrogeological settings under conditions of extreme climate variability

    USGS Publications Warehouse

    Winter, T.; Rosenberry, D.; Kelly, E.; LaBaugh, J.

    2005-01-01

    Wetlands in the Cottonwood Lake area in North Dakota, USA, are underlain by poorly permeable till and have little groundwater input. Lakes and wetlands in the Shingobee River headwaters in Minnesota are underlain by permeable sand and have substantial groundwater input. Hydrological, chemical, and biological characteristics of these ecosystems have been monitored since 1977. Both sites experienced the second worst drought of the 20th century followed by the wettest period in more than a century. At Cottonwood Lake, plants that invaded the dry wetlands during the drought were flooded during the wet period and became a food source for animals. This resulted in successive substantial population increases and declines of plankton, invertebrates, amphibians and waterfowl. Substantial groundwater input buffered the lakes and wetlands in the Shingobee area against the changing water conditions. Only subtle changes in water chemistry and plankton populations were observed during the transition from drought to deluge.

  4. The chemistry of acetone at extreme conditions by density functional molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Ferrante, Francesco; Celso, Fabrizio Lo; Triolo, Roberto; Taleyarkhan, Rusi P.

    2011-02-01

    Density functional molecular dynamics simulations have been performed in the NVT ensemble (moles (N), volume (V) and temperature (T)) on a system formed by ten acetone molecules at a temperature of 2000 K and density ρ = 1.322 g cm-3. These conditions resemble closely those realized at the interface of an acetone vapor bubble in the early stages of supercompression experiments and result in an average pressure of 5 GPa. Two relevant reactive events occur during the simulation: the condensation of two acetone molecules to give hexane-2,5-dione and dihydrogen and the isomerization to the enolic propen-2-ol form. The mechanisms of these events are discussed in detail.

  5. The chemistry of acetone at extreme conditions by density functional molecular dynamics simulations.

    PubMed

    Ferrante, Francesco; Lo Celso, Fabrizio; Triolo, Roberto; Taleyarkhan, Rusi P

    2011-02-14

    Density functional molecular dynamics simulations have been performed in the NVT ensemble (moles (N), volume (V) and temperature (T)) on a system formed by ten acetone molecules at a temperature of 2000 K and density ρ = 1.322 g cm(-3). These conditions resemble closely those realized at the interface of an acetone vapor bubble in the early stages of supercompression experiments and result in an average pressure of 5 GPa. Two relevant reactive events occur during the simulation: the condensation of two acetone molecules to give hexane-2,5-dione and dihydrogen and the isomerization to the enolic propen-2-ol form. The mechanisms of these events are discussed in detail.

  6. Biological Membranes in Extreme Conditions: Simulations of Anionic Archaeal Tetraether Lipid Membranes.

    PubMed

    Pineda De Castro, Luis Felipe; Dopson, Mark; Friedman, Ran

    2016-01-01

    In contrast to the majority of organisms that have cells bound by di-ester phospholipids, archaeal membranes consist of di- and tetraether phospholipids. Originating from organisms that withstand harsh conditions (e.g., low pH and a wide range of temperatures) such membranes have physical properties that make them attractive materials for biological research and biotechnological applications. We developed force-field parameters based on the widely used Generalized Amber Force Field (GAFF) to enable the study of anionic tetraether membranes of the model archaean Sulfolobus acidocaldarius by computer simulations. The simulations reveal that the physical properties of these unique membranes depend on the number of cyclopentane rings included in each lipid unit, and on the size of cations that are used to ensure charge neutrality. This suggests that the biophysical properties of Sulfolobus acidocaldarius cells depend not only on the compositions of their membranes but also on the media in which they grow.

  7. Biological Membranes in Extreme Conditions: Simulations of Anionic Archaeal Tetraether Lipid Membranes

    PubMed Central

    Pineda De Castro, Luis Felipe; Dopson, Mark

    2016-01-01

    In contrast to the majority of organisms that have cells bound by di-ester phospholipids, archaeal membranes consist of di- and tetraether phospholipids. Originating from organisms that withstand harsh conditions (e.g., low pH and a wide range of temperatures) such membranes have physical properties that make them attractive materials for biological research and biotechnological applications. We developed force-field parameters based on the widely used Generalized Amber Force Field (GAFF) to enable the study of anionic tetraether membranes of the model archaean Sulfolobus acidocaldarius by computer simulations. The simulations reveal that the physical properties of these unique membranes depend on the number of cyclopentane rings included in each lipid unit, and on the size of cations that are used to ensure charge neutrality. This suggests that the biophysical properties of Sulfolobus acidocaldarius cells depend not only on the compositions of their membranes but also on the media in which they grow. PMID:27167213

  8. A Quantile Domain Perspective on the Relationships between Optimal Grouping, Spacing and Stratification Problems.

    DTIC Science & Technology

    1982-06-01

    these results a quantile domain analog of a theorem due to Adatia and Chan (1981, Scand. Actuar . J., 193-202) on the equi- valence of optimal grouping...10 REFERENCES Adatia, A. and Chan, L. K. (1981). Relations between stratified, grouped and selected order statistics samples. Scand. Actuar . J., 193...these results a quantile domain analog of a theorem due to Adatia and Chan (1981, Scand. Actuar . J., DD I .o 1473 EDIo, TION O1 1 ov $is OSOLEE S/N

  9. The molecular gas in luminous infrared galaxies - I. CO lines, extreme physical conditions and their drivers

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Padelis P.; van der Werf, Paul P.; Xilouris, E. M.; Isaak, K. G.; Gao, Yu; Mühle, S.

    2012-11-01

    We report results from a large molecular line survey of luminous infrared galaxies (LIRGs; L IR ≳1011 L) in the local Universe (z ≤ 0.1), conducted during the last decade with the James Clerk Maxwell Telescope and the IRAM 30-m telescope. This work presents the CO and 13CO line data for 36 galaxies, further augmented by multi-J total CO line luminosities available for other infrared (IR) bright galaxies from the literature. This yields a combined sample of N = 70 galaxies with the star formation (SF) powered fraction of their IR luminosities spanning L IR (*)˜(1010-2×1012) L and a wide range of morphologies. Simple comparisons of their available CO spectral line energy distributions (SLEDs) with local ones, as well as radiative transfer models, discern a surprisingly wide range of average interstellar medium (ISM) conditions, with most of the surprises found in the high-excitation regime. These take the form of global CO SLEDs dominated by a very warm (Tkin ≳100 K) and dense (n ≥ 104 cm-3) gas phase, involving galaxy-sized (˜(few) × 109 M⊙) gas mass reservoirs under conditions that are typically found only for ˜(1-3) per cent of mass per typical SF molecular cloud in the Galaxy. Furthermore, some of the highest excitation CO SLEDs are found in ultraluminous infrared galaxies (ULIRGs; LIR ≥ 1012 L⊙) and surpass even those found solely in compact SF-powered hot spots in Galactic molecular clouds. Strong supersonic turbulence and high cosmic ray energy densities rather than far-ultraviolet/optical photons or supernova remnant induced shocks from individual SF sites can globally warm the large amounts of dense gas found in these merger-driven starbursts and easily power their extraordinary CO line excitation. This exciting possibility can now be systematically investigated with Herschel and the Atacama Large Milimeter Array (ALMA). As expected for an IR-selected (and thus SF rate selected) galaxy sample, only few 'cold' CO SLEDs are found, and for

  10. Mechanical Behavior of Tissue Simulants and Soft Tissues Under Extreme Loading Conditions

    NASA Astrophysics Data System (ADS)

    Kalcioglu, Zeynep Ilke

    Recent developments in computer-integrated surgery and in tissue-engineered constructs necessitate advances in experimental and analytical techniques in characterizing properties of mechanically compliant materials such as gels and soft tissues, particularly for small sample volumes. One goal of such developments is to quantitatively predict and mimic tissue deformation due to high rate impact events typical of industrial accidents and ballistic insults. This aim requires advances in mechanical characterization to establish tools and design principles for tissue simulant materials that can recapitulate the mechanical responses of hydrated soft tissues under dynamic contact-loading conditions. Given this motivation, this thesis studies the mechanical properties of compliant synthetic materials developed for tissue scaffold applications and of soft tissues, via modifying an established contact based technique for accurate, small scale characterization under fully hydrated conditions, and addresses some of the challenges in the implementation of this method. Two different engineered material systems composed of physically associating block copolymer gels, and chemically crosslinked networks including a solvent are presented as potential tissue simulants for ballistic applications, and compared directly to soft tissues from murine heart and liver. In addition to conventional quasistatic and dynamic bulk mechanical techniques that study macroscale elastic and viscoelastic properties, new methodologies are developed to study the small scale mechanical response of the aforementioned material systems to concentrated impact loading. The resistance to penetration and the energy dissipative constants are quantified in order to compare the deformation of soft tissues and mechanically optimized simulants, and to identify the underlying mechanisms by which the mechanical response of these tissue simulant candidates are modulated. Finally, given that soft tissues are biphasic in

  11. X-ray Raman Scattering at Extreme Conditions: Insights to Local Structure, Oxidation and Spin state

    NASA Astrophysics Data System (ADS)

    Wilke, M.; Sternemann, C.; Sahle, C.; Spiekermann, G.; Nyrow, A.; Weis, C.; Cerantola, V.; Schmidt, C.; Yavas, H.

    2015-12-01

    In the last decades, X-ray spectroscopic techniques using very intense synchrotron radiation (SR) have become indispensable tools for studying geomaterials. Due to the rather low absorption of hard X-rays, SR opens up the possibility to perform measurements in high-pressure, high temperature cells. The range of elements accessible by X-ray absorption spectroscopy (XAFS) techniques in these cells is limited by the absorption of X-rays due to the sample environment, i.e. the diamond windows. The indirect measurement of XAFS spectra by inelastic X-ray Raman scattering (XRS) provides a workaround to access absorption edges at low energies (e.g. low Z elements). Therefore, XRS enables measurements that are similar to electron energy loss spectroscopy but offer to measure at in-situ conditions and not just in vacuum. Measurements of the O K-edge of H2O from ambient to supercritical PT-conditions (up to 600°C @ 134 MPa; 400°C @ 371 MPa) were used to trace structural changes of the hydrogen-bonded network, which controls many physical and chemical properties of H2O [1]. The Fe M3,2-edge measured by XRS were used to characterize the oxidation state and local structure in crystalline compounds and glasses [2]. Furthermore, the M3,2 yields detailed insight to the crystal-field splitting and electronic spin state. In a reconnaissance study, the pressure-induced high-spin to low-spin transition of Fe in FeS between 6 and 8 GPa was measured. By multiplet calculations of the spectra for octahedral Fe2+, a difference in crystal field splitting between the two states of ca. 1.7 eV was estimated [3]. Finally, we successfully assessed the electronic structure of Fe in siderite by measurements of M and L-edge up to 50 GPa, covering the spin transition between 40 and 45 GPa. [1] Sahle et al. (2013) PNAS, doi: 10.1073/pnas.1220301110.. [2] Nyrow et al. (2014) Contrib Mineral Petrol 167, 1012. [3] Nyrow et al. (2014) Appl Phys Lett 104, 262408.

  12. Seasonal variations in microbial populations and environmental conditions in an extreme acid mine drainage environment.

    PubMed

    Edwards, K J; Gihring, T M; Banfield, J F

    1999-08-01

    Microbial populations, their distributions, and their aquatic environments were studied over a year (1997) at an acid mine drainage (AMD) site at Iron Mountain, Calif. Populations were quantified by fluorescence in situ hybridizations with group-specific probes. Probes were used for the domains Eucarya, Bacteria, and Archaea and the two species most widely studied and implicated for their role in AMD production, Thiobacillus ferrooxidans and Leptospirillum ferrooxidans. Results show that microbial populations, in relative proportions and absolute numbers, vary spatially and seasonally and correlate with geochemical and physical conditions (pH, temperature, conductivity, and rainfall). Bacterial populations were in the highest proportion (>95%) in January. Conversely, archaeal populations were in the highest proportion in July and September ( approximately 50%) and were virtually absent in the winter. Bacterial and archaeal populations correlated with conductivity and rainfall. High concentrations of dissolved solids, as reflected by high conductivity values (up to 125 mS/cm), occurred in the summer and correlated with high archaeal populations and proportionally lower bacterial populations. Eukaryotes were not detected in January, when total microbial cell numbers were lowest (<10(5) cells/ml), but eukaryotes increased at low-pH sites ( approximately 0.5) during the remainder of the year. This correlated with decreasing water temperatures (50 to 30 degrees C; January to November) and increasing numbers of prokaryotes (10(8) to 10(9) cells/ml). T. ferrooxidans was in highest abundance (>30%) at moderate pHs and temperatures ( approximately 2.5 and 20 degrees C) in sites that were peripheral to primary acid-generating sites and lowest (0 to 5%) at low-pH sites (pH approximately 0.5) that were in contact with the ore body. L. ferrooxidans was more widely distributed with respect to geochemical conditions (pH = 0 to 3; 20 to 50 degrees C) but was more abundant at

  13. Seasonal Variations in Microbial Populations and Environmental Conditions in an Extreme Acid Mine Drainage Environment

    PubMed Central

    Edwards, Katrina J.; Gihring, Thomas M.; Banfield, Jillian F.

    1999-01-01

    Microbial populations, their distributions, and their aquatic environments were studied over a year (1997) at an acid mine drainage (AMD) site at Iron Mountain, Calif. Populations were quantified by fluorescence in situ hybridizations with group-specific probes. Probes were used for the domains Eucarya, Bacteria, and Archaea and the two species most widely studied and implicated for their role in AMD production, Thiobacillus ferrooxidans and Leptospirillum ferrooxidans. Results show that microbial populations, in relative proportions and absolute numbers, vary spatially and seasonally and correlate with geochemical and physical conditions (pH, temperature, conductivity, and rainfall). Bacterial populations were in the highest proportion (>95%) in January. Conversely, archaeal populations were in the highest proportion in July and September (∼50%) and were virtually absent in the winter. Bacterial and archaeal populations correlated with conductivity and rainfall. High concentrations of dissolved solids, as reflected by high conductivity values (up to 125 mS/cm), occurred in the summer and correlated with high archaeal populations and proportionally lower bacterial populations. Eukaryotes were not detected in January, when total microbial cell numbers were lowest (<105 cells/ml), but eukaryotes increased at low-pH sites (∼0.5) during the remainder of the year. This correlated with decreasing water temperatures (50 to 30°C; January to November) and increasing numbers of prokaryotes (108 to 109 cells/ml). T. ferrooxidans was in highest abundance (>30%) at moderate pHs and temperatures (∼2.5 and 20°C) in sites that were peripheral to primary acid-generating sites and lowest (0 to 5%) at low-pH sites (pH ∼0.5) that were in contact with the ore body. L. ferrooxidans was more widely distributed with respect to geochemical conditions (pH = 0 to 3; 20 to 50°C) but was more abundant at higher temperatures and lower pHs (∼40°C; pH ∼0.5) than T. ferrooxidans

  14. Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome

    PubMed Central

    Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E.

    2015-01-01

    A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na+). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L−1 day−1 organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the “ML635J-40 aquatic group” while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus. PMID:26157422

  15. The use of lasers for achieving extreme conditions of matter, and fusion

    NASA Astrophysics Data System (ADS)

    Roberts, P. D.

    2012-05-01

    Since the early'70s AWE has focussed on indirect drive as a means of accessing high energy density regimes. We give a brief historical perspective of this work and the rationale for the construction of the ORION laser. This laser is currently in commissioning and is scheduled to commence experiments in 2012. The ORION laser is configured to provide long pulses (~ 1ns) with a high degree of pulse shape flexibility, together with synchronised short pulse (~1ps) irradiation. The paper describes how this combination should enable pressures in excess of 1 Gb and temperatures of greater than 500 eV to be achieved. The ability to access and diagnose such conditions has applications in many fields; examples are given in planetary science, astrophysics and inertial fusion energy. For these applications we first describe the approach to measuring equation of state and opacity properties in the high energy density regime. Such properties are then incorporated into integrated computer simulation codes and validated against laser experiments, some of which have been conducted recently at the OMEGA laser at the University of Rochester. The paper concludes with a discussion of inertial fusion energy and the new high energy density regimes that this would access, if successful.

  16. ON THE EXTREME POSITIVE STAR FORMATION FEEDBACK CONDITION IN SCUBA SOURCES

    SciTech Connect

    Silich, Sergiy; Tenorio-Tagle, Guillermo; Hueyotl-Zahuantitla, Filiberto; Munoz-Tunon, Casiana; Wuensch, Richard; Palous, Jan

    2010-03-01

    We present a detailed study of the hydrodynamics of the matter reinserted by massive stars via stellar winds and supernovae explosions in young assembling galaxies. We show that the interplay between the thermalization of the kinetic energy provided by massive stars, radiative cooling of the thermalized plasma, and the gravitational pull of the host galaxy lead to three different hydrodynamic regimes. These are: (1) the quasi-adiabatic supergalactic winds; (2) the bimodal flows, with mass accumulation in the central zones and gas expulsion from the outer zones of the assembling galaxy; and (3) the gravitationally bound regime, for which all of the gas returned by massive stars remains bound to the host galaxy and is likely to be reprocessed into further generations of stars. Which of the three possible solutions takes place depends on the mass of the star-forming region, its mechanical luminosity (or star formation rate), and its size. The model predicts that massive assembling galaxies with large star formation rates similar to those detected in Submillimeter Common-User Bolometric Array sources ({approx}1000 M{sub sun} yr{sup -1}) are likely to evolve in a positive star formation feedback condition, either in the bimodal or in the gravitationally bound regime. This implies that star formation in these sources may have little impact on the intergalactic medium and result instead into a fast interstellar matter enrichment, as observed in high redshift quasars.

  17. A Molecular Dynamics Study of Chemical Reactions of Solid Pentaerythritol Tetranitrate at Extreme Conditions

    SciTech Connect

    Wu, C J; Manaa, M R; Fried, L E

    2006-05-30

    We have carried out density functional based tight binding (DFTB) molecular dynamics (MD) simulation to study energetic reactions of solid Pentaerythritol Tetranitrate (PETN) at conditions approximating the Chapman-Jouguet (CJ) detonation state. We found that the initial decomposition of PETN molecular solid is characterized by uni-molecular dissociation of the NO{sub 2}groups. Interestingly, energy release from this powerful high explosive was found to proceed in several stages. The large portion of early stage energy release was found to be associated with the formation of H{sub 2}O molecules within a few picoseconds of reaction. It took nearly four times as long for majority of CO{sub 2} products to form, accompanied by a slow oscillatory conversion between CO and CO{sub 2}. The production of N{sub 2} starts after NO{sub 2} loses its oxygen atoms to hydrogen or carbon atoms to form H{sub 2}O or CO. We identified many intermediate species that emerge and contribute to reaction kinetics, and compared our simulation with a thermo-chemical equilibrium calculation. In addition, a detailed chemical kinetics of formation of H{sub 2}O, CO, and CO{sub 2} were developed. Rate constants of formations of H{sub 2}O, CO{sub 2} and N{sub 2} were reported.

  18. Men in extreme conditions: some medical and psychological aspects of the Auschwitz concentration camp.

    PubMed

    Radil-Weiss, T

    1983-08-01

    The second world war ended many years ago. Most of those who survived the stay at the German concentration camp at Auschwitz have already died of the consequences of their imprisonment; those still alive are already in the last third of their life. Is there any point in returning to the experiences of those days? Consideration of the mental hygiene of former prisoners cautions us that perhaps we should not do it. But consideration of the general interest holds that we are not entitled to ignore any knowledge that can contribute to social development--including medicine and psychology--even if acquired under unspeakably awful conditions. In addition, since the war new generations have grown up that play an increasingly significant role in various spheres of life but have little concrete information about those events; they can neither rationally nor emotionally understand how the horrors connected with fascism and the war could have happened. In a sense it is encouraging that they cannot grasp such inhuman behavior; nevertheless, we must adhere to the following motto: "Nothing must be forgotten, nobody will be forgotten." We owe it to those millions who did not survive--both the victims of the Holocaust and those who fought against it. These are arguments in favor of returning to the facts that are ineffaceably recorded somewhere in our memories. In doing so, however, we must remember that at times we are revisiting experiences of a boy of 14 as recalled by a 50-year-old man. The material below, examining the medical as well as psychological aspects of imprisonment at Auschwitz, is based on my own memories, as an adolescent imprisoned at Auschwitz. I have tried to move from this individual account to more general statements, although the methodological apparatus on which scientific analysis is usually based is absent.

  19. SOFI/Substrate integrity testing for cryogenic propellant tanks at extreme thermal gradient conditions

    NASA Astrophysics Data System (ADS)

    Haynes, M.; Fabian, P.

    2015-12-01

    Liquid propellant tank insulation for space flight requires low weight as well as high insulation factors. Use of Spray-On Foam Insulation (SOFI) is an accepted, cost effective technique for insulating a single wall cryogenic propellant tank and has been used extensively throughout the aerospace industry. Determining the bond integrity of the SOFI to the metallic substrate as well as its ability to withstand the in-service strains, both mechanical and thermal, is critical to the longevity of the insulation. This determination has previously been performed using highly volatile, explosive cryogens, which increases the test costs enormously, as well as greatly increasing the risk to both equipment and personnel. CTD has developed a new test system, based on a previous NASA test that simulates the mechanical and thermal strains associated with filling a large fuel tank with a cryogen. The test enables a relatively small SOFI/substrate sample to be monitored for any deformations, delaminations, or disjunctures during the cooling and mechanical straining process of the substrate, and enables the concurrent application of thermal and physical strains to two specimens at the same time. The thermal strains are applied by cooling the substrate to the desired cryogen temperature (from 4 K to 250 K) while maintaining the outside surface of the SOFI foam at ambient conditions. Multiple temperature monitoring points are exercised to ensure even cooling across the substrate, while at the same time, surface temperatures of the SOFI can be monitored to determine the heat flow. The system also allows for direct measurement of the strains in the substrate during the test. The test system as well as test data from testing at 20 K, for liquid Hydrogen simulation, will be discussed.

  20. Spirituality and Aging in Place: The Impact of Extreme Climatic Conditions on Domestic Gardening Practice.

    PubMed

    Adams, Joanne; Pascal, Jan; Dickson-Swift, Virginia

    2014-12-01

    There is limited research exploring how domestic water restrictions imposed as a result of drought conditions impact upon the lives of independently living older people. Within this age group (60 years plus), the domestic garden frequently forms an intrinsic component of ongoing health and well-being. Gardening practice offers components of both mental and physical activity and, for many older people, leads to emotional and spiritual connection on a number of levels. The capacity of older people to maintain a garden during a period of water restrictions is greatly reduced, and the resulting impact on health and well-being is considerable. A recent study, conducted in south-eastern Australia, aimed to determine the benefits to health and well-being of maintaining a domestic garden for older people and the impact of water restrictions on garden practice. This occurred at a time following a prolonged period of drought and, in central Victoria, a complete ban on outside watering. In-depth qualitative interviews were conducted with 10 gardeners aged between 60 and 83 who had tended their garden over an extended period. The lived experience of gardening was explored through hermeneutic phenomenological analysis. Clear benefits to health and well-being were established, and yet, the essence of this experience lay in the capacity of gardeners to remain connected to their garden despite change. The crisis imposed by ongoing drought and restricted use of water generated a strong impetus for adaptation, resilience and acceptance of change. The spiritual nature of gardening practice clearly emerged and appeared to intensify the experience of gardening and consolidate adaption to change on a number of levels. © The Author(s) 2015.

  1. Underwater Ambient Noise and Sperm Whale Click Detection during Extreme Wind Speed Conditions

    NASA Astrophysics Data System (ADS)

    Newcomb, Joal J.; Wright, Andrew J.; Kuczaj, Stan; Thames, Rachel; Hillstrom, Wesley R.; Goodman, Ralph

    2004-11-01

    The Littoral Acoustic Demonstration Center (LA DC) deployed three Environmental Acoustic Recording System (EARS) buoys in the northern Gulf of Mexico during the summers of 2001 (LADC 01) and 2002 (LADC 02). The hydrophone of each buoy was approximately 50m from the bottom in water depths of 645m to 1034m. During LADC 01 Tropical Storm Barry passed within 93nmi east of the EARS buoys. During LADC 02 Tropical Storm Isidore and Hurricane Lili passed within approximately 73nmi and 116nmi, respectively, west of the EARS buoys. The proximity of these storm systems to the EARS buoys, in conjunction with wind speed data from three nearby NDBC weather buoys, allows for the direct comparison of underwater ambient noise levels with high wind speeds. These results are compared to the G. M. Wenz spectra at frequencies from 1kHz to 5.5kHz. In addition, the impact of storm conditions on sperm whale clicks was assessed. In particular, although the time period during the closest approach of TS Barry tended to produce lower click rates, this time period did not have the greatest incidence of non-detection at all the EARS buoys. It follows that storm-related masking noise could not have been responsible for all the observed trends. The data suggest that sperm whales may have left the vicinity of the deepest EARS buoy (nearest TS Barry's storm track) during the storm and possibly moved into the shallower waters around the other EARS buoys. It also appears that sperm whales may not have returned to the deepest EARS area, or did not resume normal behavior immediately after the storm, as the click rate did not recover to pre-storm levels during the period after TS Barry had dissipated. Results of these analyses and the ambient noise analysis will be presented. (Research supported by ONR).

  2. The family as a determinant of stunting in children living in conditions of extreme poverty: a case-control study

    PubMed Central

    Reyes, Hortensia; Pérez-Cuevas, Ricardo; Sandoval, Araceli; Castillo, Raúl; Santos, José Ignacio; Doubova, Svetlana V; Gutiérrez, Gonzalo

    2004-01-01

    Background Malnutrition in children can be a consequence of unfavourable socioeconomic conditions. However, some families maintain adequate nutritional status in their children despite living in poverty. The aim of this study was to ascertain whether family-related factors are determinants of stunting in young Mexican children living in extreme poverty, and whether these factors differ between rural or urban contexts. Methods A case-control study was conducted in one rural and one urban extreme poverty level areas in Mexico. Cases comprised stunted children aged between 6 and 23 months. Controls were well-nourished children. Independent variables were defined in five dimensions: family characteristics; family income; household allocation of resources and family organisation; social networks; and child health care. Information was collected from 108 cases and 139 controls in the rural area and from 198 cases and 211 controls in the urban area. Statistical analysis was carried out separately for each area; unconditional multiple logistic regression analyses were performed to obtain the best explanatory model for stunting. Results In the rural area, a greater risk of stunting was associated with father's occupation as farmer and the presence of family networks for child care. The greatest protective effect was found in children cared for exclusively by their mothers. In the urban area, risk factors for stunting were father with unstable job, presence of small social networks, low rate of attendance to the Well Child Program activities, breast-feeding longer than six months, and two variables within the family characteristics dimension (longer duration of parents' union and migration from rural to urban area). Conclusions This study suggests the influence of the family on the nutritional status of children under two years of age living in extreme poverty areas. Factors associated with stunting were different in rural and urban communities. Therefore, developing and

  3. The family as a determinant of stunting in children living in conditions of extreme poverty: a case-control study.

    PubMed

    Reyes, Hortensia; Pérez-Cuevas, Ricardo; Sandoval, Araceli; Castillo, Raúl; Santos, José Ignacio; Doubova, Svetlana V; Gutiérrez, Gonzalo

    2004-11-30

    Malnutrition in children can be a consequence of unfavourable socioeconomic conditions. However, some families maintain adequate nutritional status in their children despite living in poverty. The aim of this study was to ascertain whether family-related factors are determinants of stunting in young Mexican children living in extreme poverty, and whether these factors differ between rural or urban contexts. A case-control study was conducted in one rural and one urban extreme poverty level areas in Mexico. Cases comprised stunted children aged between 6 and 23 months. Controls were well-nourished children. Independent variables were defined in five dimensions: family characteristics; family income; household allocation of resources and family organisation; social networks; and child health care. Information was collected from 108 cases and 139 controls in the rural area and from 198 cases and 211 controls in the urban area. Statistical analysis was carried out separately for each area; unconditional multiple logistic regression analyses were performed to obtain the best explanatory model for stunting. In the rural area, a greater risk of stunting was associated with father's occupation as farmer and the presence of family networks for child care. The greatest protective effect was found in children cared for exclusively by their mothers. In the urban area, risk factors for stunting were father with unstable job, presence of small social networks, low rate of attendance to the Well Child Program activities, breast-feeding longer than six months, and two variables within the family characteristics dimension (longer duration of parents' union and migration from rural to urban area). This study suggests the influence of the family on the nutritional status of children under two years of age living in extreme poverty areas. Factors associated with stunting were different in rural and urban communities.Therefore, developing and implementing health programs to tackle

  4. Syntrophic associations from hypersaline soda lakes converting organic acids and alcohols to methane at extremely haloalkaline conditions.

    PubMed

    Sorokin, Dimitry Y; Abbas, Ben; Geleijnse, Mitchell; Kolganova, Tatjana V; Kleerebezem, Robbert; van Loosdrecht, Mark C M

    2016-09-01

    Until now anaerobic oxidation of VFA at high salt-pH has been demonstrated only at sulfate-reducing conditions. Here, we present results of a microbiological investigation of anaerobic conversion of organic acids and alcohols at methanogenic conditions by syntrophic associations enriched from hypersaline soda lakes in Central Asia. Sediment incubation experiments showed active, albeit very slow, methane formation from acetate, propionate, butyrate and C2 C4 alcohols at pH 10 and various levels of salinity. Enrichments of syntrophic associations using hydrogenotrophic members of the genus Methanocalculus from soda lakes as partners resulted in several highly enriched cultures converting acetate, propionate, butyrate, benzoate and EtOH to methane. Most syntrophs belonged to Firmicutes, while the propionate-oxidizer formed a novel lineage within the family Syntrophobacteraceae in the Deltaproteobacteria. The acetate-oxidizing syntroph was identified as 'Ca. Syntrophonatronum acetioxidans' previously found to oxidize acetate at sulfate-reducing conditions up to salt-saturating concentrations. Butyrate and a benzoate-degrading syntrophs represent novel genus-level lineages in Syntrophomonadales which are proposed as Candidatus taxons 'Syntrophobaca', 'Syntrophocurvum' and 'Syntropholuna'. Overall, despite very slow growth, the results indicated the presence of a functionally competent syntrophic community in hypersaline soda lakes, capable of efficient oxidation of fermentation products to methane at extremely haloalkaline conditions.

  5. Super Clausius-Clapeyron scaling of extreme hourly precipitation and its relation to large-scale atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Lenderink, Geert; Barbero, Renaud; Loriaux, Jessica; Fowler, Hayley

    2017-04-01

    Present-day precipitation-temperature scaling relations indicate that hourly precipitation extremes may have a response to warming exceeding the Clausius-Clapeyron (CC) relation; for The Netherlands the dependency on surface dew point temperature follows two times the CC relation corresponding to 14 % per degree. Our hypothesis - as supported by a simple physical argument presented here - is that this 2CC behaviour arises from the physics of convective clouds. So, we think that this response is due to local feedbacks related to the convective activity, while other large scale atmospheric forcing conditions remain similar except for the higher temperature (approximately uniform warming with height) and absolute humidity (corresponding to the assumption of unchanged relative humidity). To test this hypothesis, we analysed the large-scale atmospheric conditions accompanying summertime afternoon precipitation events using surface observations combined with a regional re-analysis for the data in The Netherlands. Events are precipitation measurements clustered in time and space derived from approximately 30 automatic weather stations. The hourly peak intensities of these events again reveal a 2CC scaling with the surface dew point temperature. The temperature excess of moist updrafts initialized at the surface and the maximum cloud depth are clear functions of surface dew point temperature, confirming the key role of surface humidity on convective activity. Almost no differences in relative humidity and the dry temperature lapse rate were found across the dew point temperature range, supporting our theory that 2CC scaling is mainly due to the response of convection to increases in near surface humidity, while other atmospheric conditions remain similar. Additionally, hourly precipitation extremes are on average accompanied by substantial large-scale upward motions and therefore large-scale moisture convergence, which appears to accelerate with surface dew point. This

  6. Synoptic and meteorological drivers of extreme ozone concentrations over Europe

    NASA Astrophysics Data System (ADS)

    Otero, N.; Sillmann, J.; Schnell, J. L.; Rust, H. W.; Butler, T.

    2016-02-01

    The present work assesses the relationship between local and synoptic meteorological conditions and surface ozone concentration over Europe in spring and summer months, during the period 1998-2012 using a new interpolated data set of observed surface ozone concentrations over the European domain. Along with local meteorological conditions, the influence of large-scale atmospheric circulation on surface ozone is addressed through a set of airflow indices computed with a novel implementation of a grid-by-grid weather type classification across Europe. Drivers of surface ozone over the full distribution of maximum daily 8 h average values are investigated, along with drivers of the extreme high percentiles and exceedances or air quality guideline thresholds. Three different regression techniques are applied: multiple linear regression to assess the drivers of maximum daily ozone, logistic regression to assess the probability of threshold exceedances and quantile regression to estimate the meteorological influence on extreme values, as represented by the 95th percentile. The relative importance of the input parameters (predictors) is assessed by a backward stepwise regression procedure that allows the identification of the most important predictors in each model. Spatial patterns of model performance exhibit distinc