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Sample records for residence times average

  1. An estimation of the average residence times and onshore-offshore diffusivities of beached microplastics based on the population decay of tagged meso- and macrolitter.

    Science.gov (United States)

    Hinata, Hirofumi; Mori, Keita; Ohno, Kazuki; Miyao, Yasuyuki; Kataoka, Tomoya

    2017-09-15

    Residence times of microplastics were estimated based on the dependence of meso- and macrolitter residence times on their upward terminal velocities (UTVs) in the ocean obtained by one- and two-year mark-recapture experiments conducted on Wadahama Beach, Nii-jima Island, Japan. A significant linear relationship between the residence time and UTV was found in the velocity range of about 0.3-0.9ms -1 , while there was no significant difference between the residence times obtained in the velocity range of about 0.9-1.4ms -1 . This dependence on the UTV would reflect the uprush-backwash response of the target items to swash waves on the beach. By extrapolating the linear relationship down to the velocity range of microplastics, the residence times of microplastics and the 1D onshore-offshore diffusion coefficients were inferred, and are one to two orders of magnitude greater than the coefficients of the macroplastics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Flexible time domain averaging technique

    Science.gov (United States)

    Zhao, Ming; Lin, Jing; Lei, Yaguo; Wang, Xiufeng

    2013-09-01

    Time domain averaging(TDA) is essentially a comb filter, it cannot extract the specified harmonics which may be caused by some faults, such as gear eccentric. Meanwhile, TDA always suffers from period cutting error(PCE) to different extent. Several improved TDA methods have been proposed, however they cannot completely eliminate the waveform reconstruction error caused by PCE. In order to overcome the shortcomings of conventional methods, a flexible time domain averaging(FTDA) technique is established, which adapts to the analyzed signal through adjusting each harmonic of the comb filter. In this technique, the explicit form of FTDA is first constructed by frequency domain sampling. Subsequently, chirp Z-transform(CZT) is employed in the algorithm of FTDA, which can improve the calculating efficiency significantly. Since the signal is reconstructed in the continuous time domain, there is no PCE in the FTDA. To validate the effectiveness of FTDA in the signal de-noising, interpolation and harmonic reconstruction, a simulated multi-components periodic signal that corrupted by noise is processed by FTDA. The simulation results show that the FTDA is capable of recovering the periodic components from the background noise effectively. Moreover, it can improve the signal-to-noise ratio by 7.9 dB compared with conventional ones. Experiments are also carried out on gearbox test rigs with chipped tooth and eccentricity gear, respectively. It is shown that the FTDA can identify the direction and severity of the eccentricity gear, and further enhances the amplitudes of impulses by 35%. The proposed technique not only solves the problem of PCE, but also provides a useful tool for the fault symptom extraction of rotating machinery.

  3. A Time Study of Plastic Surgery Residents.

    Science.gov (United States)

    Lau, Frank H; Sinha, Indranil; Jiang, Wei; Lipsitz, Stuart R; Eriksson, Elof

    2016-05-01

    Resident work hours are under scrutiny and have been subject to multiple restrictions. The studies supporting these changes have not included data on surgical residents. We studied the workday of a team of plastic surgery residents to establish prospective time-study data of plastic surgery (PRS) residents at a single tertiary-care academic medical center. Five trained research assistants observed all residents (n = 8) on a PRS service for 10 weeks and produced minute-by-minute activity logs. Data collection began when the team first met in the morning and continued until the resident being followed completed all non-call activities. We analyzed our data from 3 perspectives: 1) time spent in direct patient care (DPC), indirect patient care, and didactic activities; 2) time spent in high education-value activities (HEAs) versus low education-value activities; and 3) resident efficiency. We defined HEAs as activities that surgeons must master; other activities were LEAs. We quantified resident efficiency in terms of time fragmentation and time spent waiting. A total of 642.4 hours of data across 50 workdays were collected. Excluding call, residents worked an average of 64.2 hours per week. Approximately 50.7% of surgical resident time was allotted to DPC, with surgery accounting for the largest segment of this time (34.8%). Time spent on HEAs demonstrated trended upward with higher resident level (P = 0.086). Time in spent in surgery was significantly associated with higher resident levels (P time study of PRS residents, we found that compared with medicine trainees, surgical residents spent 3.23 times more time on DPC. High education-value activities comprised most of our residents' workdays. Surgery was the leading component of both DPC and HEAs. Our residents were highly efficient and fragmented, with the majority of all activities requiring 4 minutes or less. Residents spent a large portion of their time waiting for other services. In light of these data, we

  4. Multistage parallel-serial time averaging filters

    International Nuclear Information System (INIS)

    Theodosiou, G.E.

    1980-01-01

    Here, a new time averaging circuit design, the 'parallel filter' is presented, which can reduce the time jitter, introduced in time measurements using counters of large dimensions. This parallel filter could be considered as a single stage unit circuit which can be repeated an arbitrary number of times in series, thus providing a parallel-serial filter type as a result. The main advantages of such a filter over a serial one are much less electronic gate jitter and time delay for the same amount of total time uncertainty reduction. (orig.)

  5. Time-averaged MSD of Brownian motion

    OpenAIRE

    Andreanov, Alexei; Grebenkov, Denis

    2012-01-01

    We study the statistical properties of the time-averaged mean-square displacements (TAMSD). This is a standard non-local quadratic functional for inferring the diffusion coefficient from an individual random trajectory of a diffusing tracer in single-particle tracking experiments. For Brownian motion, we derive an exact formula for the Laplace transform of the probability density of the TAMSD by mapping the original problem onto chains of coupled harmonic oscillators. From this formula, we de...

  6. Asymptotic Time Averages and Frequency Distributions

    Directory of Open Access Journals (Sweden)

    Muhammad El-Taha

    2016-01-01

    Full Text Available Consider an arbitrary nonnegative deterministic process (in a stochastic setting {X(t,  t≥0} is a fixed realization, i.e., sample-path of the underlying stochastic process with state space S=(-∞,∞. Using a sample-path approach, we give necessary and sufficient conditions for the long-run time average of a measurable function of process to be equal to the expectation taken with respect to the same measurable function of its long-run frequency distribution. The results are further extended to allow unrestricted parameter (time space. Examples are provided to show that our condition is not superfluous and that it is weaker than uniform integrability. The case of discrete-time processes is also considered. The relationship to previously known sufficient conditions, usually given in stochastic settings, will also be discussed. Our approach is applied to regenerative processes and an extension of a well-known result is given. For researchers interested in sample-path analysis, our results will give them the choice to work with the time average of a process or its frequency distribution function and go back and forth between the two under a mild condition.

  7. Time-averaged MSD of Brownian motion

    Science.gov (United States)

    Andreanov, Alexei; Grebenkov, Denis S.

    2012-07-01

    We study the statistical properties of the time-averaged mean-square displacements (TAMSD). This is a standard non-local quadratic functional for inferring the diffusion coefficient from an individual random trajectory of a diffusing tracer in single-particle tracking experiments. For Brownian motion, we derive an exact formula for the Laplace transform of the probability density of the TAMSD by mapping the original problem onto chains of coupled harmonic oscillators. From this formula, we deduce the first four cumulant moments of the TAMSD, the asymptotic behavior of the probability density and its accurate approximation by a generalized Gamma distribution.

  8. Time averaging, ageing and delay analysis of financial time series

    Science.gov (United States)

    Cherstvy, Andrey G.; Vinod, Deepak; Aghion, Erez; Chechkin, Aleksei V.; Metzler, Ralf

    2017-06-01

    We introduce three strategies for the analysis of financial time series based on time averaged observables. These comprise the time averaged mean squared displacement (MSD) as well as the ageing and delay time methods for varying fractions of the financial time series. We explore these concepts via statistical analysis of historic time series for several Dow Jones Industrial indices for the period from the 1960s to 2015. Remarkably, we discover a simple universal law for the delay time averaged MSD. The observed features of the financial time series dynamics agree well with our analytical results for the time averaged measurables for geometric Brownian motion, underlying the famed Black-Scholes-Merton model. The concepts we promote here are shown to be useful for financial data analysis and enable one to unveil new universal features of stock market dynamics.

  9. Residence time determination for adsorbent beds of different configurations

    Energy Technology Data Exchange (ETDEWEB)

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-02-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis.

  10. Residence time determination for adsorbent beds of different configurations

    International Nuclear Information System (INIS)

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-01-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis

  11. The residence time of water in the atmosphere revisited

    NARCIS (Netherlands)

    Van Der Ent, Ruud J.; Tuinenburg, Obbe A.

    2017-01-01

    This paper revisits the knowledge on the residence time of water in the atmosphere. Based on state-of-the-art data of the hydrological cycle we derive a global average residence time of 8.9 ± 0.4 days (uncertainty given as 1 standard deviation). We use two different atmospheric moisture tracking

  12. Resident characterization of better-than- and worse-than-average clinical teaching.

    Science.gov (United States)

    Haydar, Bishr; Charnin, Jonathan; Voepel-Lewis, Terri; Baker, Keith

    2014-01-01

    Clinical teachers and trainees share a common view of what constitutes excellent clinical teaching, but associations between these behaviors and high teaching scores have not been established. This study used residents' written feedback to their clinical teachers, to identify themes associated with above- or below-average teaching scores. All resident evaluations of their clinical supervisors in a single department were collected from January 1, 2007 until December 31, 2008. A mean teaching score assigned by each resident was calculated. Evaluations that were 20% higher or 15% lower than the resident's mean score were used. A subset of these evaluations was reviewed, generating a list of 28 themes for further study. Two researchers then, independently coded the presence or absence of these themes in each evaluation. Interrater reliability of the themes and logistic regression were used to evaluate the predictive associations of the themes with above- or below-average evaluations. Five hundred twenty-seven above-average and 285 below-average evaluations were evaluated for the presence or absence of 15 positive themes and 13 negative themes, which were divided into four categories: teaching, supervision, interpersonal, and feedback. Thirteen of 15 positive themes correlated with above-average evaluations and nine had high interrater reliability (Intraclass Correlation Coefficient >0.6). Twelve of 13 negative themes correlated with below-average evaluations, and all had high interrater reliability. On the basis of these findings, the authors developed 13 recommendations for clinical educators. The authors developed 13 recommendations for clinical teachers using the themes identified from the above- and below-average clinical teaching evaluations submitted by anesthesia residents.

  13. Drug target residence time: a misleading concept.

    Science.gov (United States)

    Folmer, Rutger H A

    2018-01-01

    Since the importance of drug target residence time was first highlighted more 10 years ago, slow binding kinetics has received much attention in the drug discovery literature, and indeed within pharmaceutical research. However, the residence concept as presented in most papers is supported by rather misleading simulations and arguments, and by examples where compounds are taken out of their pharmacokinetic context. Moreover, fast association is typically more desirable than slow, and advantages of long residence time, notably a potential disconnect between pharmacodynamics (PD) and pharmacokinetics (PK), would be partially or completely offset by slow on-rate. Therefore, plain potency is likely a better predictor of drug development success than is residence time. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Subdiffusion in time-averaged, confined random walks.

    Science.gov (United States)

    Neusius, Thomas; Sokolov, Igor M; Smith, Jeremy C

    2009-07-01

    Certain techniques characterizing diffusive processes, such as single-particle tracking or molecular dynamics simulation, provide time averages rather than ensemble averages. Whereas the ensemble-averaged mean-squared displacement (MSD) of an unbounded continuous time random walk (CTRW) with a broad distribution of waiting times exhibits subdiffusion, the time-averaged MSD, delta2, does not. We demonstrate that, in contrast to the unbounded CTRW, in which delta2 is linear in the lag time Delta, the time-averaged MSD of the CTRW of a walker confined to a finite volume is sublinear in Delta, i.e., for long lag times delta2 approximately Delta1-alpha. The present results permit the application of CTRW to interpret time-averaged experimental quantities.

  15. Time average vibration fringe analysis using Hilbert transformation

    International Nuclear Information System (INIS)

    Kumar, Upputuri Paul; Mohan, Nandigana Krishna; Kothiyal, Mahendra Prasad

    2010-01-01

    Quantitative phase information from a single interferogram can be obtained using the Hilbert transform (HT). We have applied the HT method for quantitative evaluation of Bessel fringes obtained in time average TV holography. The method requires only one fringe pattern for the extraction of vibration amplitude and reduces the complexity in quantifying the data experienced in the time average reference bias modulation method, which uses multiple fringe frames. The technique is demonstrated for the measurement of out-of-plane vibration amplitude on a small scale specimen using a time average microscopic TV holography system.

  16. Salecker-Wigner-Peres clock and average tunneling times

    Energy Technology Data Exchange (ETDEWEB)

    Lunardi, Jose T., E-mail: jttlunardi@uepg.b [Departamento de Matematica e Estatistica, Universidade Estadual de Ponta Grossa, Av. General Carlos Cavalcanti, 4748. Cep 84030-000, Ponta Grossa, PR (Brazil); Manzoni, Luiz A., E-mail: manzoni@cord.ed [Department of Physics, Concordia College, 901 8th St. S., Moorhead, MN 56562 (United States); Nystrom, Andrew T., E-mail: atnystro@cord.ed [Department of Physics, Concordia College, 901 8th St. S., Moorhead, MN 56562 (United States)

    2011-01-17

    The quantum clock of Salecker-Wigner-Peres is used, by performing a post-selection of the final state, to obtain average transmission and reflection times associated to the scattering of localized wave packets by static potentials in one dimension. The behavior of these average times is studied for a Gaussian wave packet, centered around a tunneling wave number, incident on a rectangular barrier and, in particular, on a double delta barrier potential. The regime of opaque barriers is investigated and the results show that the average transmission time does not saturate, showing no evidence of the Hartman effect (or its generalized version).

  17. Historical Data for Average Processing Time Until Hearing Held

    Data.gov (United States)

    Social Security Administration — This dataset provides historical data for average wait time (in days) from the hearing request date until a hearing was held. This dataset includes data from fiscal...

  18. Instantaneous, phase-averaged, and time-averaged pressure from particle image velocimetry

    Science.gov (United States)

    de Kat, Roeland

    2015-11-01

    Recent work on pressure determination using velocity data from particle image velocimetry (PIV) resulted in approaches that allow for instantaneous and volumetric pressure determination. However, applying these approaches is not always feasible (e.g. due to resolution, access, or other constraints) or desired. In those cases pressure determination approaches using phase-averaged or time-averaged velocity provide an alternative. To assess the performance of these different pressure determination approaches against one another, they are applied to a single data set and their results are compared with each other and with surface pressure measurements. For this assessment, the data set of a flow around a square cylinder (de Kat & van Oudheusden, 2012, Exp. Fluids 52:1089-1106) is used. RdK is supported by a Leverhulme Trust Early Career Fellowship.

  19. Average weighted receiving time in recursive weighted Koch networks

    Indian Academy of Sciences (India)

    https://www.ias.ac.in/article/fulltext/pram/086/06/1173-1182. Keywords. Weighted Koch network; recursive division method; average weighted receiving time. Abstract. Motivated by the empirical observation in airport networks and metabolic networks, we introduce the model of the recursive weighted Koch networks created ...

  20. Concentration fluctuations and averaging time in vapor clouds

    CERN Document Server

    Wilson, David J

    2010-01-01

    This book contributes to more reliable and realistic predictions by focusing on sampling times from a few seconds to a few hours. Its objectives include developing clear definitions of statistical terms, such as plume sampling time, concentration averaging time, receptor exposure time, and other terms often confused with each other or incorrectly specified in hazard assessments; identifying and quantifying situations for which there is no adequate knowledge to predict concentration fluctuations in the near-field, close to sources, and far downwind where dispersion is dominated by atmospheric t

  1. Residence time and physical processes in lakes

    Directory of Open Access Journals (Sweden)

    Nicoletta SALA

    2003-09-01

    Full Text Available The residence time of a lake is highly dependent on internal physical processes in the water mass conditioning its hydrodynamics; early attempts to evaluate this physical parameter emphasize the complexity of the problem, which depends on very different natural phenomena with widespread synergies. The aim of this study is to analyse the agents involved in these processes and arrive at a more realistic definition of water residence time which takes account of these agents, and how they influence internal hydrodynamics. With particular reference to temperate lakes, the following characteristics are analysed: 1 the set of the lake's caloric components which, along with summer heating, determine the stabilizing effect of the surface layers, and the consequent thermal stratification, as well as the winter destabilizing effect; 2 the wind force, which transfers part of its momentum to the water mass, generating a complex of movements (turbulence, waves, currents with the production of active kinetic energy; 3 the water flowing into the lake from the tributaries, and flowing out through the outflow, from the standpoint of hydrology and of the kinetic effect generated by the introduction of these water masses into the lake. These factors were studied in the context of the general geographical properties of the lake basin and the watershed (latitude, longitude, morphology, also taking account of the local and regional climatic situation. Also analysed is the impact of ongoing climatic change on the renewal of the lake water, which is currently changing the equilibrium between lake and atmosphere, river and lake, and relationships

  2. Is average daily travel time expenditure constant? In search of explanations for an increase in average travel time.

    NARCIS (Netherlands)

    van Wee, B.; Rietveld, P.; Meurs, H.

    2006-01-01

    Recent research suggests that the average time spent travelling by the Dutch population has increased over the past decades. However, different data sources show different levels of increase. This paper explores possible causes for this increase. They include a rise in incomes, which has probably

  3. Comparing averaging limits for social cues over space and time.

    Science.gov (United States)

    Florey, Joseph; Dakin, Steven C; Mareschal, Isabelle

    2017-08-01

    Observers are able to extract summary statistics from groups of faces, such as their mean emotion or identity. This can be done for faces presented simultaneously and also from sequences of faces presented at a fixed location. Equivalent noise analysis, which estimates an observer's internal noise (the uncertainty in judging a single element) and effective sample size (ESS; the effective number of elements being used to judge the average), reveals what limits an observer's averaging performance. It has recently been shown that observers have lower ESSs and higher internal noise for judging the mean gaze direction of a group of spatially distributed faces compared to the mean head direction of the same faces. In this study, we use the equivalent noise technique to compare limits on these two cues to social attention under two presentation conditions: spatially distributed and sequentially presented. We find that the differences in ESS are replicated in spatial arrays but disappear when both cue types are averaged over time, suggesting that limited peripheral gaze perception prevents accurate averaging performance. Correlation analysis across participants revealed generic limits for internal noise that may act across stimulus and presentation types, but no clear shared limits for ESS. This result supports the idea of some shared neural mechanisms b in early stages of visual processing.

  4. Atmospheric residence times of continental aerosols

    International Nuclear Information System (INIS)

    Balkanski, Y.J.

    1991-01-01

    The global atmospheric distributions of Rn-222 are simulated with a three-dimensional model of atmospheric transport based on the meteorology of the NASA Goddard Institute for Space Studies (GISS) general circulation model. The short-lived radioactive gas Rn-222 (half-life = 3.8d) is emitted almost exclusively from land, at a relatively uniform rate; hence it is an excellent tracer of continental influences. Lead-210 is produced by decay of Rn-222 and immediately condenses to preexisting aerosol surfaces. It provides an excellent measure of aerosol residence times in the atmosphere because its source is accurately defined by the Rn-222 distribution. Results from the three-dimensional model are compared to measurements of Rn-222 and Pb-210 atmospheric concentrations to evaluate model's long-range transport over oceanic regions and to study the deposition mechanisms of atmospheric aerosols. Model results for Rn-222 are used to examine the long-range transport of continental air over two selected oceanic regions, the subantarctic Indian Ocean and the North Pacific. It is shown that the fast transport of air from southern Africa causes substantial continental pollution at southern mid-latitudes, a region usually regarded as pristine. Air over the North Pacific is heavily impacted by continental influences year round, but the altitude at which the transport occurs varies seasonally. Observations of aerosols at island sites, which are commonly used as diagnostics of continental influences, may be misleading because they do not account for influences at high altitude and because aerosols are efficiently scavenged by deposition during transport. The study of Pb-210 focuses on defining the residence times of submicron aerosols in the troposphere. Scavenging in wet convective updrafts is found to provide the dominant sink on a global scale

  5. A note on computing average state occupation times

    Directory of Open Access Journals (Sweden)

    Jan Beyersmann

    2014-05-01

    Full Text Available Objective: This review discusses how biometricians would probably compute or estimate expected waiting times, if they had the data. Methods: Our framework is a time-inhomogeneous Markov multistate model, where all transition hazards are allowed to be time-varying. We assume that the cumulative transition hazards are given. That is, they are either known, as in a simulation, determined by expert guesses, or obtained via some method of statistical estimation. Our basic tool is product integration, which transforms the transition hazards into the matrix of transition probabilities. Product integration enjoys a rich mathematical theory, which has successfully been used to study probabilistic and statistical aspects of multistate models. Our emphasis will be on practical implementation of product integration, which allows us to numerically approximate the transition probabilities. Average state occupation times and other quantities of interest may then be derived from the transition probabilities.

  6. Averaged multivalued solutions and time discretization for conservation laws

    International Nuclear Information System (INIS)

    Brenier, Y.

    1985-01-01

    It is noted that the correct shock solutions can be approximated by averaging in some sense the multivalued solution given by the method of characteristics for the nonlinear scalar conservation law (NSCL). A time discretization for the NSCL equation based on this principle is considered. An equivalent analytical formulation is shown to lead quite easily to a convergence result, and a third formulation is introduced which can be generalized for the systems of conservation laws. Various numerical schemes are constructed from the proposed time discretization. The first family of schemes is obtained by using a spatial grid and projecting the results of the time discretization. Many known schemes are then recognized (mainly schemes by Osher, Roe, and LeVeque). A second way to discretize leads to a particle scheme without space grid, which is very efficient (at least in the scalar case). Finally, a close relationship between the proposed method and the Boltzmann type schemes is established. 14 references

  7. Average waiting time profiles of uniform DQDB model

    Energy Technology Data Exchange (ETDEWEB)

    Rao, N.S.V. [Oak Ridge National Lab., TN (United States); Maly, K.; Olariu, S.; Dharanikota, S.; Zhang, L.; Game, D. [Old Dominion Univ., Norfolk, VA (United States). Dept. of Computer Science

    1993-09-07

    The Distributed Queue Dual Bus (DQDB) system consists of a linear arrangement of N nodes that communicate with each other using two contra-flowing buses; the nodes use an extremely simple protocol to send messages on these buses. This simple, but elegant, system has been found to be very challenging to analyze. We consider a simple and uniform abstraction of this model to highlight the fairness issues in terms of average waiting time. We introduce a new approximation method to analyze the performance of DQDB system in terms of the average waiting time of a node expressed as a function of its position. Our approach abstracts the intimate relationship between the load of the system and its fairness characteristics, and explains all basic behavior profiles of DQDB observed in previous simulation. For the uniform DQDB with equal distance between adjacent nodes, we show that the system operates under three basic behavior profiles and a finite number of their combinations that depend on the load of the network. Consequently, the system is not fair at any load in terms of the average waiting times. In the vicinity of a critical load of 1 {minus} 4/N, the uniform network runs into a state akin to chaos, where its behavior fluctuates from one extreme to the other with a load variation of 2/N. Our analysis is supported by simulation results. We also show that the main theme of the analysis carries over to the general (non-uniform) DQDB; by suitably choosing the inter-node distances, the DQDB can be made fair around some loads, but such system will become unfair as the load changes.

  8. A time Fourier analysis of zonal averaged ozone heating rates

    Science.gov (United States)

    Wang, P.-H.; Wu, M.-F.; Deepak, A.; Hong, S.-S.

    1981-01-01

    A time-Fourier analysis is presented for the yearly variation of the zonal averaged ozone heating rates in the middle atmosphere based on a model study. The ozone heating rates are determined by utilizing two-dimensional ozone distributions, the altitude and latitude, and by including the effect of the curved earth's atmosphere. In addition, assumptions are introduced to the yearly variations of the ozone distributions due to the lack of sufficient existing ozone data. Among other results, it is shown that the first harmonic component indicates that the heating rates are completely out of phase between the northern and southern hemispheres. The second Fourier component shows a symmetric pattern with respect to the equator, as well as five distinct local extreme values of the ozone heating rate. The third harmonic component shows a pattern close to that of the first component except in the regions above 70 deg between 45-95 km in both hemispheres.

  9. Passive magnetic bearing systems stabilizer/bearing utilizing time-averaging of a periodic magnetic field

    Science.gov (United States)

    Post, Richard F.

    2017-10-03

    A high-stiffness stabilizer/bearings for passive magnetic bearing systems is provide where the key to its operation resides in the fact that when the frequency of variation of the repelling forces of the periodic magnet array is large compared to the reciprocal of the growth time of the unstable motion, the rotating system will feel only the time-averaged value of the force. When the time-averaged value of the force is radially repelling by the choice of the geometry of the periodic magnet array, the Earnshaw-related unstable hit motion that would occur at zero rotational speed is suppressed when the system is rotating at operating speeds.

  10. Prolonged and tunable residence time using reversible covalent kinase inhibitors.

    Science.gov (United States)

    Bradshaw, J Michael; McFarland, Jesse M; Paavilainen, Ville O; Bisconte, Angelina; Tam, Danny; Phan, Vernon T; Romanov, Sergei; Finkle, David; Shu, Jin; Patel, Vaishali; Ton, Tony; Li, Xiaoyan; Loughhead, David G; Nunn, Philip A; Karr, Dane E; Gerritsen, Mary E; Funk, Jens Oliver; Owens, Timothy D; Verner, Erik; Brameld, Ken A; Hill, Ronald J; Goldstein, David M; Taunton, Jack

    2015-07-01

    Drugs with prolonged on-target residence times often show superior efficacy, yet general strategies for optimizing drug-target residence time are lacking. Here we made progress toward this elusive goal by targeting a noncatalytic cysteine in Bruton's tyrosine kinase (BTK) with reversible covalent inhibitors. Using an inverted orientation of the cysteine-reactive cyanoacrylamide electrophile, we identified potent and selective BTK inhibitors that demonstrated biochemical residence times spanning from minutes to 7 d. An inverted cyanoacrylamide with prolonged residence time in vivo remained bound to BTK for more than 18 h after clearance from the circulation. The inverted cyanoacrylamide strategy was further used to discover fibroblast growth factor receptor (FGFR) kinase inhibitors with residence times of several days, demonstrating the generalizability of the approach. Targeting of noncatalytic cysteines with inverted cyanoacrylamides may serve as a broadly applicable platform that facilitates 'residence time by design', the ability to modulate and improve the duration of target engagement in vivo.

  11. Elective time during dermatology residency: A survey of residents and program directors.

    Science.gov (United States)

    Uppal, Pushpinder; Shantharam, Rohini; Kaufmann, Tara Lynn

    2017-12-15

    Elective time during residency training provides residents with exposure to different subspecialties. This opportunity gives residents the chance tonurture growth in particular areas of interest and broaden their knowledge base in certain topics in dermatology by having the chance to work withexperts in the field. The purpose of this study was to assess the views of residency program directors and dermatology residents on the value of elective time through a cross sectional survey. An eight-questionIRB exempt survey was sent out to 113 residency program directors via email through the American Professors of Dermatology (APD) program director listserv. Program directors were asked to forward a separate set of 9 questions to their residents. The majority of programs that responded allowed for some elective time within their schedule, often duringthe PGY 4 (3rd year of dermatology training), but the amount of time allowed widely varied among many residency programs. Overall, residents and program directors agree that elective is important in residencytraining, but no standardization is established across programs.

  12. Bounds on Average Time Complexity of Decision Trees

    KAUST Repository

    Chikalov, Igor

    2011-01-01

    In this chapter, bounds on the average depth and the average weighted depth of decision trees are considered. Similar problems are studied in search theory [1], coding theory [77], design and analysis of algorithms (e.g., sorting) [38]. For any diagnostic problem, the minimum average depth of decision tree is bounded from below by the entropy of probability distribution (with a multiplier 1/log2 k for a problem over a k-valued information system). Among diagnostic problems, the problems with a complete set of attributes have the lowest minimum average depth of decision trees (e.g, the problem of building optimal prefix code [1] and a blood test study in assumption that exactly one patient is ill [23]). For such problems, the minimum average depth of decision tree exceeds the lower bound by at most one. The minimum average depth reaches the maximum on the problems in which each attribute is "indispensable" [44] (e.g., a diagnostic problem with n attributes and kn pairwise different rows in the decision table and the problem of implementing the modulo 2 summation function). These problems have the minimum average depth of decision tree equal to the number of attributes in the problem description. © Springer-Verlag Berlin Heidelberg 2011.

  13. Long residence times - bad tracer tests?

    Science.gov (United States)

    Ghergut, Julia; Behrens, Horst; Sauter, Martin

    2015-04-01

    Tracer tests conducted at geothermal well doublets or triplets in the Upper Rhine Rift Valley [1] all face, with very few exceptions so far, one common issue: lack of conclusive tracer test results, or tracer signals still undetectable for longer than one or two years after tracer injection. While the reasons for this surely differ from site to site (Riehen, Landau, Insheim, Bruchsal, ...), its effects on how the usefulness of tracer tests is perceived by the non-tracer community are pretty much the same. The 'poor-signal' frustration keeps nourishing two major 'alternative' endeavours : (I) design and execute tracer tests in single-well injection-withdrawal (push-pull), 'instead of' inter-well flow-path tracing configurations; (II) use 'novel' tracer substances instead of the 'old' ones which have 'obviously failed'. Frustration experienced with most inter-well tracer tests in the Upper Rhine Rift Valley has also made them be regarded as 'maybe useful for EGS' ('enhanced', or 'engineered' geothermal systems, whose fluid RTD typically include a major share of values below one year), but 'no longer worthwhile a follow-up sampling' in natural, large-scale hydrothermal reservoirs. We illustrate some of these arguments with the ongoing Bruchsal case [2]. The inter-well tracer test conducted at Bruchsal was (and still is!) aimed at assessing inter-well connectivity, fluid residence times, and characterizing the reservoir structure [3]. Fluid samples taken at the geothermal production well after reaching a fluid turnover of about 700,000 m3 showed tracer concentrations in the range of 10-8 Minj per m3, in the liquid phase of each sample (Minj being the total quantity of tracer injected as a short pulse at the geothermal re-injection well). Tracer signals might actually be higher, owing to tracer amounts co-precipitated and/or adsorbed onto the solid phase whose accumulation in the samples was unavoidable (due to pressure relief and degassing during the very sampling

  14. A constant travel time budget? In search for explanations for an increase in average travel time

    NARCIS (Netherlands)

    Rietveld, P.; Wee, van B.

    2002-01-01

    Recent research suggests that during the past decades the average travel time of the Dutch population has probably increased. However, different datasources show different levels of increase. Possible causes of the increase in average travel time are presented here. Increased incomes have

  15. Residence time modeling of hot melt extrusion processes.

    Science.gov (United States)

    Reitz, Elena; Podhaisky, Helmut; Ely, David; Thommes, Markus

    2013-11-01

    The hot melt extrusion process is a widespread technique to mix viscous melts. The residence time of material in the process frequently determines the product properties. An experimental setup and a corresponding mathematical model were developed to evaluate residence time and residence time distribution in twin screw extrusion processes. The extrusion process was modeled as the convolution of a mass transport process described by a Gaussian probability function, and a mixing process represented by an exponential function. The residence time of the extrusion process was determined by introducing a tracer at the extruder inlet and measuring the tracer concentration at the die. These concentrations were fitted to the residence time model, and an adequate correlation was found. Different parameters were derived to characterize the extrusion process including the dead time, the apparent mixing volume, and a transport related axial mixing. A 2(3) design of experiments was performed to evaluate the effect of powder feed rate, screw speed, and melt viscosity of the material on the residence time. All three parameters affect the residence time of material in the extruder. In conclusion, a residence time model was developed to interpret experimental data and to get insights into the hot melt extrusion process. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Modelling travel and residence times in the eastern Irish Sea

    International Nuclear Information System (INIS)

    Dabrowski, T.; Hartnett, M.

    2008-01-01

    The Irish Sea, which lies between 51 deg. N-56 deg. N and 2 deg. 50'W-7 deg. W, provides a sheltered environment to exploit valuable fisheries resource. Anthropogenic activity is a real threat to its water quality. The majority of freshwater input down rivers flows into the eastern Irish Sea. The structure of the water circulation was not well understood during the planning of Sellafield nuclear plant outfall site in the eastern Irish Sea. A three-dimensional primitive equation numerical model was applied to the Irish Sea to simulate both barotropic and baroclinic circulation within the region. High accuracy was achieved with regard to the prediction of both tidal circulation and surface and nearbed water temperatures across the region. The model properly represented the Western Irish Sea Gyre, induced by thermal stratification and not known during planning Sellafield. Passive tracer simulations based on the developed hydrodynamic model were used to deliver residence times of the eastern Irish Sea region for various times of the year as well as travel times from the Sellafield outfall site to various locations within the Irish Sea. The results indicate a strong seasonal variability of travel times from Sellafield to the examined locations. Travel time to the Clyde Sea is the shortest for the autumnal tracer release (90 days); it takes almost a year for the tracer to arrive at the same location if it is released in January. Travel times from Sellafield to Dublin Bay fall within the range of 180-360 days. The average residence time of the entire eastern Irish Sea is around 7 months. The areas surrounding the Isle of Man are initially flushed due to a predominant northward flow; a backwater is formed in Liverpool Bay. Thus, elevated tracer concentrations are predicted in Liverpool Bay in the case of accidental spills at the Sellafield outfall site

  17. Markov analysis for estimation of residence time | Agunwamba ...

    African Journals Online (AJOL)

    Accurate estimation of residence time is very useful for the design of water and wastewater treatment plants. Its determination is difficult because it depends on complex interaction among many factors such as geometry, hydrodynamic and environmental factors. In this paper, the estimation of residence time is formulated as ...

  18. DNA residence time is a regulatory factor of transcription repression.

    Science.gov (United States)

    Clauß, Karen; Popp, Achim P; Schulze, Lena; Hettich, Johannes; Reisser, Matthias; Escoter Torres, Laura; Uhlenhaut, N Henriette; Gebhardt, J Christof M

    2017-11-02

    Transcription comprises a highly regulated sequence of intrinsically stochastic processes, resulting in bursts of transcription intermitted by quiescence. In transcription activation or repression, a transcription factor binds dynamically to DNA, with a residence time unique to each factor. Whether the DNA residence time is important in the transcription process is unclear. Here, we designed a series of transcription repressors differing in their DNA residence time by utilizing the modular DNA binding domain of transcription activator-like effectors (TALEs) and varying the number of nucleotide-recognizing repeat domains. We characterized the DNA residence times of our repressors in living cells using single molecule tracking. The residence times depended non-linearly on the number of repeat domains and differed by more than a factor of six. The factors provoked a residence time-dependent decrease in transcript level of the glucocorticoid receptor-activated gene SGK1. Down regulation of transcription was due to a lower burst frequency in the presence of long binding repressors and is in accordance with a model of competitive inhibition of endogenous activator binding. Our single molecule experiments reveal transcription factor DNA residence time as a regulatory factor controlling transcription repression and establish TALE-DNA binding domains as tools for the temporal dissection of transcription regulation. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  19. Experimental determination of residence time distribution in continuous dry granulation.

    Science.gov (United States)

    Mangal, Haress; Kleinebudde, Peter

    2017-05-30

    With increasing importance of continuous manufacturing, the interest in integrating dry granulation into a continuous manufacturing line is growing. Residence time distribution measurements are of importance as they provide information about duration of materials within the process. These data enable traceability and are highly beneficial for developing control strategies. A digital image analysis system was used to determine the residence time distribution of two materials with different deformation behavior (brittle, plastic) in the milling unit of dry granulation systems. A colorant was added to the material (20%w/w iron oxide), which did not affect the material properties excessively, so the milling process could be mimicked well. Experimental designs were conducted to figure out which parameters effect the mean residence time strongly. Moreover, two types of dry granulation systems were contrasted. Longer mean residence times were obtained for the oscillating mill (OM) compared to the conical mill (CM). For co-processed microcrystalline cellulose residence times of 19.8-44.4s (OM) and 11.6-29.1s (CM) were measured, mainly influenced by the specific compaction force, the mill speed and roll speed. For dibasic calcium phosphate anhydrate residence times from 17.7-46.4 (OM) and 5.4-10.2s (CM) were measured, while here the specific compaction force, the mill speed and their interactions with the roll speed had an influence on the mean residence time. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Disability Reconsideration Average Processing Time (in Days) (Excludes technical denials)

    Data.gov (United States)

    Social Security Administration — A presentation of the overall cumulative number of elapsed days (including processing time for transit, medical determinations, and SSA quality review) from the date...

  1. SEASONAL AUTOREGRESSIVE INTEGRATED MOVING AVERAGE MODEL FOR PRECIPITATION TIME SERIES

    OpenAIRE

    Yan Wang; Meng Gao; Xinghua Chang; Xiyong Hou

    2012-01-01

    Predicting the trend of precipitation is a difficult task in meteorology and environmental sciences. Statistical approaches from time series analysis provide an alternative way for precipitation prediction. The ARIMA model incorporating seasonal characteristics, which is referred to as seasonal ARIMA model was presented. The time series data is the monthly precipitation data in Yantai, China and the period is from 1961 to 2011. The model was denoted as SARIMA (1, 0, 1) (0, 1, 1)12 in this stu...

  2. Classifying terrestrial surface water systems using integrated residence time

    Science.gov (United States)

    Jones, Allan; Hodges, Ben; McClelland, James; Hardison, Amber; Moffett, Kevan

    2017-04-01

    Linkages between ecology and hydrology in terrestrial surface water often invoke a discussion of lentic (reservoir) vs. lotic (riverine) system behaviors. However, the literature shows a wide range of thresholds separating lentic/lotic regimes and little agreement on a quantitative, repeatable classification metric that can be broadly and reliably applied across a range of systems hosting various flow regimes and suspended/benthic taxa. We propose an integrated Residence Time (iTR) metric as part of a new Freshwater Continuum Classification (FCC) to address this issue. The iTR is computed as the transit time of a water parcel across a system given observed temporal variations in discharge and volume, which creates a temporally-varying metric applicable across a defined system length. This approach avoids problems associated with instantaneous residence times or average residence times that can lead to misleading characterizations in seasonally- or episodically-dynamic systems. The iTR can be directly related to critical flow thresholds and timescales of ecology (e.g., zooplankton growth). The FCC approach considers lentic and lotic to be opposing end-members of a classification continuum and also defines intermediate regimes that blur the line between the two ends of the spectrum due to more complex hydrological system dynamics. We also discover the potential for "oscillic" behavior, where a system switches between lentic and lotic classifications either episodically or regularly (e.g., seasonally). Oscillic behavior is difficult to diagnose with prior lentic/lotic classification schemes, but can be readily identified using iTR. The FCC approach was used to analyze 15 tidally-influenced river segments along the Texas (USA) coast of the Gulf of Mexico. The results agreed with lentic/lotic designations using prior approaches, but also identified more nuanced intermediate and oscillic regimes. Within this set of systems, the oscillic nature of some of the river

  3. Prediction of residence time distributions in food processing machinery

    DEFF Research Database (Denmark)

    Karlson, Torben; Friis, Alan; Szabo, Peter

    1996-01-01

    The velocity field in a co-rotating disc scraped surface heat exchanger (CDHE) is calculated using a finite element method. The residence time distribution for the CDHE is then obtained by tracing particles introduced in the inlet....

  4. Children's postdivorce residence arrangements and parental experienced time pressure

    NARCIS (Netherlands)

    van der Heijden, Franciëlla; Poortman, Anne Rigt; van der Lippe, Tanja

    2016-01-01

    Although the rise in postdivorce joint physical custody has fueled scholarly interest in its impact on children, consequences for parents remain understudied. Because children's residence arrangements determine time and coordination demands associated with child care, this study investigated the

  5. Residence time distribution studies on water-softening reactors

    International Nuclear Information System (INIS)

    Baranyai, L.

    1989-01-01

    Based on radiotracer techniques residence time distribution (RTD) studies were carried out on a water-softening reactor consisting of three physically separated units in order to characterize its hydrodynamical behaviour. The measured RTD curves and the actual mean residence times were compared with the theoretical values set up by modelling the reactor as a hydrodynamical system. Neither mixing nor sedimentation reaches ideal flow. The flow type in the settling cylinder is far of that what is expected. (author)

  6. Prediction of residence time distributions in food processing machinery

    DEFF Research Database (Denmark)

    Karlson, Torben; Friis, Alan; Szabo, Peter

    1996-01-01

    The velocity field in a co-rotating disc scraped surface heat exchanger (CDHE) is calculated using a finite element method. The residence time distribution for the CDHE is then obtained by tracing particles introduced in the inlet.......The velocity field in a co-rotating disc scraped surface heat exchanger (CDHE) is calculated using a finite element method. The residence time distribution for the CDHE is then obtained by tracing particles introduced in the inlet....

  7. Connections between residence time distributions and watershed characteristics across the continental US

    Science.gov (United States)

    Condon, L. E.; Maxwell, R. M.; Kollet, S. J.; Maher, K.; Haggerty, R.; Forrester, M. M.

    2016-12-01

    Although previous studies have demonstrated fractal residence time distributions in small watersheds, analyzing residence time scaling over large spatial areas is difficult with existing observational methods. For this study we use a fully integrated groundwater surface water simulation combined with Lagrangian particle tracking to evaluate connections between residence time distributions and watershed characteristics such as geology, topography and climate. Our simulation spans more than six million square kilometers of the continental US, encompassing a broad range of watershed sizes and physiographic settings. Simulated results demonstrate power law residence time distributions with peak age rages from 1.5 to 10.5 years. These ranges agree well with previous observational work and demonstrate the feasibility of using integrated models to simulate residence times. Comparing behavior between eight major watersheds, we show spatial variability in both the peak and the variance of the residence time distributions that can be related to model inputs. Peak age is well correlated with basin averaged hydraulic conductivity and the semi-variance corresponds to aridity. While power law age distributions have previously been attributed to fractal topography, these results illustrate the importance of subsurface characteristics and macro climate as additional controls on groundwater configuration and residence times.

  8. Residents' perception of skill decay during dedicated research time.

    Science.gov (United States)

    D'Angelo, Anne-Lise D; Ray, Rebecca D; Jenewein, Caitlin G; Jones, Grace F; Pugh, Carla M

    2015-11-01

    Surgery residents may take years away from clinical responsibilities for dedicated research time. As part of a longitudinal project, the study aim was to investigate residents' perceptions of clinical skill reduction during dedicated research time. Our hypothesis was that residents would perceive a greater potential reduction in skill during research time for procedures they were less confident in performing. Surgical residents engaged in dedicated research training at multiple training programs participated in four simulated procedures: urinary catheterization, subclavian central line, bowel anastomosis, and laparoscopic ventral hernia (LVH) repair. Using preprocedure and postprocedure surveys, participants rated procedures for confidence and difficulty. Residents also indicated the perceived level of skills reduction for the four procedures as a result of time in the laboratory. Thirty-eight residents (55% female) completed the four clinical simulators. Participants had between 0-36 mo in a laboratory (M = 9.29 mo, standard deviation = 9.38). Preprocedure surveys noted lower confidence and higher perceived difficulty for performing the LVH repair followed by bowel anastomosis, central line insertion, and urinary catheterization (P perception for urinary catheterization (P perception and may provide a mechanism for maintaining skills and keeping confidence grounded in experience. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Allocation of Internal Medicine Resident Time in a Swiss Hospital: A Time and Motion Study of Day and Evening Shifts.

    Science.gov (United States)

    Wenger, Nathalie; Méan, Marie; Castioni, Julien; Marques-Vidal, Pedro; Waeber, Gérard; Garnier, Antoine

    2017-04-18

    Little current evidence documents how internal medicine residents spend their time at work, particularly with regard to the proportions of time spent in direct patient care versus using computers. To describe how residents allocate their time during day and evening hospital shifts. Time and motion study. Internal medicine residency at a university hospital in Switzerland, May to July 2015. 36 internal medicine residents with an average of 29 months of postgraduate training. Trained observers recorded the residents' activities using a tablet-based application. Twenty-two activities were categorized as directly related to patients, indirectly related to patients, communication, academic, nonmedical tasks, and transition. In addition, the presence of a patient or colleague and use of a computer or telephone during each activity was recorded. Residents were observed for a total of 696.7 hours. Day shifts lasted 11.6 hours (1.6 hours more than scheduled). During these shifts, activities indirectly related to patients accounted for 52.4% of the time, and activities directly related to patients accounted for 28.0%. Residents spent an average of 1.7 hours with patients, 5.2 hours using computers, and 13 minutes doing both. Time spent using a computer was scattered throughout the day, with the heaviest use after 6:00 p.m. The study involved a small sample from 1 institution. At this Swiss teaching hospital, internal medicine residents spent more time at work than scheduled. Activities indirectly related to patients predominated, and about half the workday was spent using a computer. Information Technology Department and Department of Internal Medicine of Lausanne University Hospital.

  10. Optimal bounds and extremal trajectories for time averages in dynamical systems

    Science.gov (United States)

    Tobasco, Ian; Goluskin, David; Doering, Charles

    2017-11-01

    For systems governed by differential equations it is natural to seek extremal solution trajectories, maximizing or minimizing the long-time average of a given quantity of interest. A priori bounds on optima can be proved by constructing auxiliary functions satisfying certain point-wise inequalities, the verification of which does not require solving the underlying equations. We prove that for any bounded autonomous ODE, the problems of finding extremal trajectories on the one hand and optimal auxiliary functions on the other are strongly dual in the sense of convex duality. As a result, auxiliary functions provide arbitrarily sharp bounds on optimal time averages. Furthermore, nearly optimal auxiliary functions provide volumes in phase space where maximal and nearly maximal trajectories must lie. For polynomial systems, such functions can be constructed by semidefinite programming. We illustrate these ideas using the Lorenz system, producing explicit volumes in phase space where extremal trajectories are guaranteed to reside. Supported by NSF Award DMS-1515161, Van Loo Postdoctoral Fellowships, and the John Simon Guggenheim Foundation.

  11. Halogen-aromatic π-interactions modulate inhibitor residence time.

    Science.gov (United States)

    Heroven, Christina; Georgi, Victoria; Ganotra, Gaurav K; Brennan, Paul E; Wolfreys, Finn; Wade, Rebecca C; Fernández-Montalván, Amaury E; Chaikuad, Apirat; Knapp, Stefan

    2018-03-30

    Prolonged drug residence times may result in longer lasting drug efficacy, improved pharmacodynamic properties and "kinetic selectivity" over off-targets with fast drug dissociation rates. However, few strategies have been elaborated to rationally modulate drug residence time and thereby to integrate this key property into the drug development process. Here, we show that the interaction between a halogen moiety on an inhibitor and an aromatic residue in the target protein can significantly increase inhibitor residence time. By using the interaction of the serine/threonine kinase haspin with 5-iodotubercidin (5-iTU) derivatives as a model for an archetypal active state (type I) kinase-inhibitor binding mode, we demonstrate that inhibitor residence times markedly increase with the size and polarizability of the halogen atom. This key interaction is dependent on the interactions with an aromatic residue in the gatekeeper position and we observe this interaction in other kinases with an aromatic gatekeeper residue. We provide a detailed mechanistic characterization of the halogen-aromatic π interactions in the haspin-inhibitor complexes by means of kinetic, thermodynamic, and structural measurements along with binding energy calculations. Since halogens are frequently used in drugs and aromatic residues are often present in the binding sites of proteins, our results provide a compelling rationale for introducing aromatic-halogen interactions to prolong drug-target residence times. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Real time curriculum map for internal medicine residency.

    Science.gov (United States)

    Wong, Roger Y; Roberts, J Mark

    2007-11-07

    To manage the voluminous formal curriculum content in a limited amount of structured teaching time, we describe the development and evaluation of a curriculum map for academic half days (AHD) in a core internal medicine residency program. We created a 3-year cyclical curriculum map (an educational tool combining the content, methodology and timetabling of structured teaching), comprising a matrix of topics under various specialties/themes and corresponding AHD hours. All topics were cross-matched against the ACP-ASIM in-training examination, and all hours were colour coded based on the categories of core competencies. Residents regularly updated the map on a real time basis. There were 208 topics covered in 283 AHD hours. All topics represented core competencies with minimal duplication (78% covered once in 3 years). Only 42 hours (15%) involved non-didactic teaching, which increased after implementation of the map (18-19 hours/year versus baseline 5 hours/year). Most AHD hours (78%) focused on medical expert competencies. Resident satisfaction (90% response) was high throughout (range 3.64 +/- 0.21, 3.84 +/- 0.14 out of 4), which improved after 1 year but returned to baseline after 2 years. We developed and implemented an internal medicine curriculum map based on real time resident input, with minimal topic duplication and high resident satisfaction. The map provided an opportunity to balance didactic versus non-didactic teaching, and teaching on medical versus non medical expert topics.

  13. On time-dependent perturbation theory in matrix mechanics and time averaging

    International Nuclear Information System (INIS)

    Casas, Fernando

    2015-01-01

    The time-dependent quantum perturbation theory developed by Born, Heisenberg and Jordan in 1926 is revisited. We show that it not only reproduces the standard theory formulated in the interaction picture, but also allows one to construct more accurate approximations if time averaging techniques are employed. The theory can be rendered unitary even if the expansion is truncated by using a transformation previously suggested by Heisenberg. We illustrate the main features of the procedure on a simple example which clearly shows its advantages in comparison with the standard perturbation theory. (paper)

  14. Effect of oven residence time on mechanical properties in ...

    Indian Academy of Sciences (India)

    Simulation studies were conducted using ROTOSIM software to analyze thermal transitions and phase changes during the process. Degree of curing of the polymers was also assessed and correlated with mechanical properties. Experiments were further conducted to obtain favourable oven residence time to obtain highest ...

  15. Studies on steps affecting tritium residence time in solid blanket

    International Nuclear Information System (INIS)

    Tanaka, Satoru

    1987-01-01

    For the self sustaining of CTR fuel cycle, the effective tritium recovery from blankets is essential. This means that not only tritium breeding ratio must be larger than 1.0, but also high recovering speed is required for the short residence time of tritium in blankets. Short residence time means that the tritium inventory in blankets is small. In this paper, the tritium residence time and tritium inventory in a solid blanket are modeled by considering the steps constituting tritium release. Some of these tritium migration processes were experimentally evaluated. The tritium migration steps in a solid blanket using sintered breeding materials consist of diffusion in grains, desorption at grain edges, diffusion and permeation through grain boundaries, desorption at particle edges, diffusion and percolation through interconnected pores to purging stream, and convective mass transfer to stream. Corresponding to these steps, diffusive, soluble, adsorbed and trapped tritium inventories and the tritium in gas phase are conceivable. The code named TTT was made for calculating these tritium inventories and the residence time of tritium. An example of the results of calculation is shown. The blanket is REPUTER-1, which is the conceptual design of a commercial reversed field pinch fusion reactor studied at the University of Tokyo. The experimental studies on the migration steps of tritium are reported. (Kako, I.)

  16. Relationships between removal processes and residence times for atmospheric pollutants

    International Nuclear Information System (INIS)

    Slinn, W.G.N.

    1978-01-01

    This report is concerned with improving estimates for the residence times of atmospheric trace constituents in various atmospheric reservoirs. Residence times are defined only for steady-state conditions; i.e., when the net growth rate vanishes. The most useful case of vanishing net growth rate is when the total growth rate is equal to the decay rate. It is demonstrated that the most important advance towards improving estimates of pollutant residence times is through proper choices of reservoirs. Chosen reservoirs should possess the following features: steady-state conditions, uniform mixing ratio throughout or throughout specified subreservoirs, and subreservoirs chosen in which removal rates can be treated as approximate constants. An example of a poorly mixed reservoir, the stratosphere, is discussed. In another example, it is suggested that commonly used reservoirs for atmospheric CO 2 have been chosen poorly and that a substantial portion of the anthropogenic CO 2 released during the past 50 years may still be mixing into the stratosphere. In another example, it is suggested that determination of the dry deposition velocity for accumulation-mode aerosol particles may not be so important as previously thought. To improve estimates for the atmospheric residence times of these particles, it is important to increase knowledge of what is called the ascension velocity

  17. Effect of oven residence time on mechanical properties in ...

    Indian Academy of Sciences (India)

    In rotational moulding of plastics, improving the mechanical properties without sacrificing the processibility is a challenging task. In this paper, an attempt has been made to investigate the effect of oven residence time on the mechanical properties of the rotationally moulded products made using linear low ...

  18. [Analysis on status and determinants of outpatient service utilization of rural floating population in Beijing at different residence time].

    Science.gov (United States)

    2017-06-18

    To study the status and identify the determinants of outpatient service utilization of rural floating population in Beijing who have different accumulated residence time. The survey data of rural floating population health and health care services in Beijing in 2014 were used, and the migrant population aged 18 years and above were taken as the research object. Whether to use outpatient service within two weeks was taken as dependent variable, gender, age, education level, self-assessment score of socioeconomic status, accumulated residence time in Beijing, health insurance, average household income, suffering from high blood pressure or diabetes as independent variables. Logistic regression model was used to analyze the influencing factors. The average age of the research object was 36.7 years, with mostly secondary education. The average accumulated residence time in Beijing was 8.4 years. The two-week prevalence rate was 10.3%, the two-week visiting rate calculated by person-time was 6.0%. The Logistic regression model suggested that, socioeconomic status, accumulated residence time and suffering from high blood pressure or diabetes were statistically significant determinants of outpatient service utilization. The research object is a younger and less educated population, their health status is better and outpatient service utilization is lower. It is found that people who have longer accumulated residence time in Beijing have lower outpatient service utilization. This is because people with longer residence time have lower age-adjusted two-week prevalence rate. This is also because people with longer residence time have larger proportion of taking continuous measures under doctor's advice. It does not mean people with longer residence time have lower utilization of medical service. The residence time variable plays the role of proxy variable. It can solve the problem of variables' endoge-neity. At the same time, it can reflect the influence to outpatient

  19. Financial and Time Burdens for Medical Students Interviewing for Residency.

    Science.gov (United States)

    Callaway, Paul; Melhado, Trisha; Walling, Anne; Groskurth, Jordan

    2017-02-01

    Interviewing for residency positions is increasingly stressful for students and challenging for programs. Little information is available about the costs and time invested by students in interviewing or about the key factors in decisions to accept interview offers. Our objective was to assess the time and financial costs of residency interviewing for an entire class at a regional campus and explore factors influencing student decisions to accept interviews. We used a 14-item survey administered electronically immediately following National Resident Matching Program results. The response rate was 75% (49 of 65 students). About half interviewed in primary care specialties. Thirty students (63%) applied to 20 or more programs, and 91% were offered multiple interviews out of state. Seventy percent limited interviews by time and cost. Other important factors included personal "fit," program reputation, and the quality of residents. About 50% of the students spent more than 20 days and $1,000-$5,000 interviewing; 29% reported spending over $5,000. Students used multiple funding sources, predominantly loans and savings. Primary care applicants applied to fewer out-of-state programs, reported fewer interview days and lower expenses, but received more financial support from programs. Students invested considerable time and resources in interviewing, and these factors significantly influenced their decisions about accepting interviews. The other major factors in interview decisions concerned personal comfort with the program, especially the residents. The costs and time reported in this study could be greater than other schools due to the regional campus location or lower due to the high proportion of students interviewing in primary care.

  20. Modeling the Residence Time of Mobile Bay in Alabama

    Science.gov (United States)

    Han, M. M.; Park, K.

    2016-02-01

    The Three-dimensional Hydrodynamic-Eutrophication Model/Environmental Fluid Dynamics Code (HEM3D/EFDC) was used to calculate the residence time of Mobile Bay in Alabama using Eulerian passive tracer method. Mobile Bay is about 50 km long and 20 km wide, so it can be divided into several sections which may have different residence times. Three typical boundary conditions that affect residence time are tide, river discharge, and wind. Mobile Bay is located in the northern Gulf of Mexico and is a micro-tidal region. Two most important tidal components here are K1 and O1, and the maximum tidal range of tropic (spring) tide is less than 0.6 m. There is a difference between the simulation results with and without tidal condition (K1+O1) even though the tidal range is relatively smaller than that in macro-tidal regions. Also the minimum, mean, and maximum of daily mean river discharge for 38 years (1976-2013) in Mobile and Tensaw River are 80.7 m3/s, 1700.8 m3/s, and 14186.7 m3/s respectively, and there are daily, monthly, seasonal, and annual variations. The residence time can be largely affected by the river discharge because of its large deviation. Even though the dominant wind here is southerly in the spring and summer and is northerly in the fall and winter, the wind speed and direction change over time. Continuous winds from similar directions can reduce and increase the residence time such as the southerly, southwesterly, northerly, and northeasterly winds in alignment with the direction of the inlet and outlet of Mobile Bay. Also the short term changes of wind direction and speed can affect it complicatedly. Therefore, the simulations with the combinations of three boundary conditions allow us to understand the water circulation in Mobile Bay well and to predict the residence time when some accidents happen such as contaminations by factories, sewage plants, ships and oil spills.

  1. Real time curriculum map for internal medicine residency

    Directory of Open Access Journals (Sweden)

    Roberts J Mark

    2007-11-01

    Full Text Available Abstract Background To manage the voluminous formal curriculum content in a limited amount of structured teaching time, we describe the development and evaluation of a curriculum map for academic half days (AHD in a core internal medicine residency program. Methods We created a 3-year cyclical curriculum map (an educational tool combining the content, methodology and timetabling of structured teaching, comprising a matrix of topics under various specialties/themes and corresponding AHD hours. All topics were cross-matched against the ACP-ASIM in-training examination, and all hours were colour coded based on the categories of core competencies. Residents regularly updated the map on a real time basis. Results There were 208 topics covered in 283 AHD hours. All topics represented core competencies with minimal duplication (78% covered once in 3 years. Only 42 hours (15% involved non-didactic teaching, which increased after implementation of the map (18–19 hours/year versus baseline 5 hours/year. Most AHD hours (78% focused on medical expert competencies. Resident satisfaction (90% response was high throughout (range 3.64 ± 0.21, 3.84 ± 0.14 out of 4, which improved after 1 year but returned to baseline after 2 years. Conclusion We developed and implemented an internal medicine curriculum map based on real time resident input, with minimal topic duplication and high resident satisfaction. The map provided an opportunity to balance didactic versus non-didactic teaching, and teaching on medical versus non medical expert topics.

  2. On the evaluation of Hardy's thermomechanical quantities using ensemble and time averaging

    International Nuclear Information System (INIS)

    Fu, Yao; To, Albert C

    2013-01-01

    An ensemble averaging approach was investigated for its accuracy and convergence against time averaging in computing continuum quantities such as stress, heat flux and temperature from atomistic scale quantities. For this purpose, ensemble averaging and time averaging were applied to evaluate Hardy's thermomechanical expressions (Hardy 1982 J. Chem. Phys. 76 622–8) in equilibrium conditions at two different temperatures as well as a nonequilibrium process due to shock impact on a Ni crystal modeled using molecular dynamics simulations. It was found that under equilibrium conditions, time averaging requires selection of a time interval larger than the critical time interval to obtain convergence, where the critical time interval can be estimated using the elastic properties of the material. The reason for this is because of the significant correlations among the computed thermomechanical quantities at different time instants employed in computing their time average. On the other hand, the computed thermomechanical quantities from different realizations in ensemble averaging are statistically independent, and thus convergence is always guaranteed. The computed stress, heat flux and temperature show noticeable difference in their convergence behavior while their confidence intervals increase with temperature. Contrary to equilibrium settings, time averaging is not equivalent to ensemble averaging in the case of shock wave propagation. Time averaging was shown to have poor performance in computing various thermomechanical fields by either oversmoothing the fields or failing to remove noise. (paper)

  3. Influence of dispatching rules on average production lead time for multi-stage production systems.

    Science.gov (United States)

    Hübl, Alexander; Jodlbauer, Herbert; Altendorfer, Klaus

    2013-08-01

    In this paper the influence of different dispatching rules on the average production lead time is investigated. Two theorems based on covariance between processing time and production lead time are formulated and proved theoretically. Theorem 1 links the average production lead time to the "processing time weighted production lead time" for the multi-stage production systems analytically. The influence of different dispatching rules on average lead time, which is well known from simulation and empirical studies, can be proved theoretically in Theorem 2 for a single stage production system. A simulation study is conducted to gain more insight into the influence of dispatching rules on average production lead time in a multi-stage production system. We find that the "processing time weighted average production lead time" for a multi-stage production system is not invariant of the applied dispatching rule and can be used as a dispatching rule independent indicator for single-stage production systems.

  4. Public Inquiry Data - Average Processing Time (in days) - FY 2014 Onward

    Data.gov (United States)

    Social Security Administration — This dataset shows the average processing time for completed inquiries. The data source is the Electronic Management of Assignments and Correspondence system (EMAC)....

  5. Mean Residence Time and Emergency Drinking Water Supply.

    Science.gov (United States)

    Kralik, Martin; Humer, Franko

    2013-04-01

    Immediately after securing an endangered population, the first priority of aid workers following a disaster is the distribution of drinking water. Such emergency situations are reported from many parts of the world following regional chemical or nuclear pollution accidents, floods, droughts, rain-induced landslides, tsunami, and other extreme events. It is often difficult to organise a replacement water supply when regular water systems with short residence times are polluted, infiltrated or even flooded by natural or man-made disasters. They are either unusable or their restoration may take months or even years. Groundwater resources, proven safe and protected by the geological environment, with long residence times and the necessary infrastructure for their exploitation, would provide populations with timeous replacement of vulnerable water supply systems and make rescue activities more rapid and effective. Such resources have to be identified and investigated, as a substitute for affected drinking water supplies thereby eliminating or reducing the impact of their failure following catastrophic events. Even in many areas such water resources with long residence times in years or decades are difficult to find it should be known which water supply facilities in the region are matching these requirements to allow in emergency situation the transport of water in tankers to the affected regions to prevent epidemics, importing large quantities of bottled water. One should know the residence time of the water supply to have sufficient time to plan and install new safe water supply facilities. Development of such policy and strategy for human security - both long term and short term - is therefore needed to decrease the vulnerability of populations threatened by extreme events and water supplies with short residence times. Generally: The longer the residence time of groundwater in the aquifer, the lower its vulnerability. The most common and economic methods to estimate

  6. Probabilistic approach of water residence time and connectivity using Markov chains with application to tidal embayments

    Science.gov (United States)

    Bacher, C.; Filgueira, R.; Guyondet, T.

    2016-01-01

    Markov chain analysis was recently proposed to assess the time scales and preferential pathways into biological or physical networks by computing residence time, first passage time, rates of transfer between nodes and number of passages in a node. We propose to adapt an algorithm already published for simple systems to physical systems described with a high resolution hydrodynamic model. The method is applied to bays and estuaries on the Eastern Coast of Canada for their interest in shellfish aquaculture. Current velocities have been computed by using a 2 dimensional grid of elements and circulation patterns were summarized by averaging Eulerian flows between adjacent elements. Flows and volumes allow computing probabilities of transition between elements and to assess the average time needed by virtual particles to move from one element to another, the rate of transfer between two elements, and the average residence time of each system. We also combined transfer rates and times to assess the main pathways of virtual particles released in farmed areas and the potential influence of farmed areas on other areas. We suggest that Markov chain is complementary to other sets of ecological indicators proposed to analyse the interactions between farmed areas - e.g., depletion index, carrying capacity assessment. Markov chain has several advantages with respect to the estimation of connectivity between pair of sites. It makes possible to estimate transfer rates and times at once in a very quick and efficient way, without the need to perform long term simulations of particle or tracer concentration.

  7. The residence time of intensively managed agricultural landscapes

    Science.gov (United States)

    Bowling, Laura; Cherkauer, Keith; Chiu, Chun-mei; Rahman, Sanoar

    2015-04-01

    Much of the agricultural landscape across the Midwestern United States is intensively managed through numerous surface and subsurface drainage improvements, and the growing extraction of groundwater resources. The relatively recent glaciation of the North Central region means that the landscape is less dissected and hydrologically connected than older till areas. Low topographic gradients and underlying dense till which restricts vertical water movement, as well as kettle depressions, have led to poorly drained soils and extensive wetlands within the landscape. Large areas of this land could only be farmed once the excess water was removed through artificial surface and subsurface drainage. Conventional wisdom in the region maintains that subsurface tile drainage reduces the occurrence of peak flow events by increasing soil water storage capacity. At the watershed scale, this view does not take into account the coincident increase in surface drainage and reduction in residence time in surface depressions. This paper explores to what degree water management and irrigation has changed surface and subsurface water storage and residence time over the last century and how this has impacted flow duration throughout the Wabash River system in Indiana, USA. The effects of subsurface tile drains, wetlands and aquifer storage are explicitly represented within the Variable Infiltration Capacity (VIC) macroscale hydrology model. We maintain a focus on the entire Wabash River, a river system of historic importance that is also representative of many similar areas in the till plain region of the agricultural Midwest, which contribute to water quality and flood dynamics of the Mississippi river system. By lowering the water table, surface and subsurface drainage improvements have increased the subsurface storage capacity at the beginning of rain events, but this is overwhelmed by the decrease in surface storage capacity for intermediate to large events, decreasing the current

  8. Dynamic time warping-based averaging framework for functional near-infrared spectroscopy brain imaging studies

    Science.gov (United States)

    Zhu, Li; Najafizadeh, Laleh

    2017-06-01

    We investigate the problem related to the averaging procedure in functional near-infrared spectroscopy (fNIRS) brain imaging studies. Typically, to reduce noise and to empower the signal strength associated with task-induced activities, recorded signals (e.g., in response to repeated stimuli or from a group of individuals) are averaged through a point-by-point conventional averaging technique. However, due to the existence of variable latencies in recorded activities, the use of the conventional averaging technique can lead to inaccuracies and loss of information in the averaged signal, which may result in inaccurate conclusions about the functionality of the brain. To improve the averaging accuracy in the presence of variable latencies, we present an averaging framework that employs dynamic time warping (DTW) to account for the temporal variation in the alignment of fNIRS signals to be averaged. As a proof of concept, we focus on the problem of localizing task-induced active brain regions. The framework is extensively tested on experimental data (obtained from both block design and event-related design experiments) as well as on simulated data. In all cases, it is shown that the DTW-based averaging technique outperforms the conventional-based averaging technique in estimating the location of task-induced active regions in the brain, suggesting that such advanced averaging methods should be employed in fNIRS brain imaging studies.

  9. Asymptotic behaviour of time averages for non-ergodic Gaussian processes

    Science.gov (United States)

    Ślęzak, Jakub

    2017-08-01

    In this work, we study the behaviour of time-averages for stationary (non-ageing), but ergodicity-breaking Gaussian processes using their representation in Fourier space. We provide explicit formulae for various time-averaged quantities, such as mean square displacement, density, and analyse the behaviour of time-averaged characteristic function, which gives insight into rich memory structure of the studied processes. Moreover, we show applications of the ergodic criteria in Fourier space, determining the ergodicity of the generalised Langevin equation's solutions.

  10. The determination of residence times in a pilot plant

    Science.gov (United States)

    Ramírez, F. Pablo; Cortés, M. Eugenia

    2004-01-01

    It is well known that residence time distributions (RTD) are very important in many chemical processes such as separation, reforming, hydrocracking, fluid catalytic cracking, hydrodesulfuration, hydrogenation among others [3 Procédés de transformation, Editions Technip, Institute Francais du Petrole, Paris, France, 1998]. In addition, tracers can be used to measure the velocity, distribution and residence time of any stream through any part of an industrial [Guidebook on Radioisotope Tracers in Industry, IAEA, Vienna, 1990] or experimental system. Perhaps the best quality of radiotracers is that they do not interfere with normal unit operations or production scheduling. In this paper are presented the RTDs obtained in a pilot plant for a hydrogenation process [IMP, Technical Report, Determinación del tiempo de residencia promedio en el reactor de la planta piloto de hidroagotamiento de crudo, 2002]. The RTDs show a random phenomenon, which is not typical of this type of chemical processes. Several RTDs were determined in order to confirm this random behavior. The data were obtained using as a tracer a radioactive form of sodium iodide containing iodine-131 [The Condensed Chemical Dictionary, 10th Ed., Van Nostrand Reinhold, USA, 1981]. The process works with two phases in a countercurrent flow, inside a packed column. The liquid phase goes down by gravity. The gas phase goes up due to pressure difference [3 Procédés de transformation, Editions Technip, Institute Francais du Petrole, Paris, France, 1998]. The tracer was selected such that it would follow the liquid phase.

  11. Residence Times in Central Valley Aquifers Recharged by Dammed Rivers

    Science.gov (United States)

    Loustale, M.; Paukert Vankeuren, A. N.; Visser, A.

    2017-12-01

    Groundwater is a vital resource for California, providing between 30-60% of the state's water supply. Recent emphasis on groundwater sustainability has induced a push to characterize recharge rates and residence times for high priority aquifers, including most aquifers in California's Central Valley. Flows in almost all rivers from the western Sierra to the Central Valley are controlled by dams, altering natural flow patterns and recharge to local aquifers. In eastern Sacramento, unconfined and confined shallow aquifers (depth BGS. Variation in groundwater age in the vertical and horizontal directions are used to determine groundwater flow path and velocity. These data are then used to calculate residence time of groundwater in the unconfined and confined aquifer systems for the Central Valley in eastern Sacramento. Applying groundwater age tracers can benefit future compliance metrics of the California Sustainable Groundwater Resources Act (SGMA), by quantifying river seepage rates and impacts of groundwater management on surface water resources. 1Moran et al., UCRL-TR-203258, 2004.

  12. Policy Iteration for Continuous-Time Average Reward Markov Decision Processes in Polish Spaces

    Directory of Open Access Journals (Sweden)

    Quanxin Zhu

    2009-01-01

    Full Text Available We study the policy iteration algorithm (PIA for continuous-time jump Markov decision processes in general state and action spaces. The corresponding transition rates are allowed to be unbounded, and the reward rates may have neither upper nor lower bounds. The criterion that we are concerned with is expected average reward. We propose a set of conditions under which we first establish the average reward optimality equation and present the PIA. Then under two slightly different sets of conditions we show that the PIA yields the optimal (maximum reward, an average optimal stationary policy, and a solution to the average reward optimality equation.

  13. Average Wait Time Until Hearing Held Report (By Month), September 2016 (53rd week)

    Data.gov (United States)

    Social Security Administration — A presentation of the average time (in months) from the hearing request date until a hearing is held for claims pending in the Office of Disability Adjudication and...

  14. Extra-regional residence time as a correlate of plant invasiveness: European archaeophytes in North America.

    Science.gov (United States)

    La Sorte, Frank A; Pysek, Petr

    2009-09-01

    Human activities have degraded biogeographical barriers to dispersal resulting in the spread and naturalization of increasing numbers of nonnative invasive species. One correlate of invasiveness within a region is residence time or time since introduction. Plant species that were introduced into Europe prior to AD 1500 (European archaeophytes) that were subsequently introduced into North America provide a unique opportunity to examine the effect of extra-regional residence time (i.e., residence time that occurred in a nonnative region before a species was introduced into a new region). Here, we examine how nonnative species with extensive extra-regional residence times have affected beta diversity among states in the contiguous United States of America based on an analysis of occupancy and distance decay of similarity. State floras contained an average of 3106 +/- 922 species (mean +/- SD) with 2318 +/- 757 species classified as native, 180 +/- 43 species as European archaeophyte, and 608 -236 species as other exotic with no European archaeophyte association. For European archaeophytes, 42% were identified as noxious weeds in the United States with 8% identified as agricultural and 14% as natural-area weeds (20%, 2%, and 13% for other exotics, respectively). In strong contrast to natives and other exotics, European archaeophytes were more widespread and presented weaker distance-decay patterns. Thus, European archaeophytes were more likely to become noxious weeds, particularly within agricultural areas, and were associated with significant losses in beta diversity. We suggest that this outcome is a consequence of extra-regional residence time, which allowed for the selection of species or the evolution of traits that favored the colonization of arable habitats associated with early agricultural activities in Europe, habitats that are widespread, resource rich, and uniformly distributed in the United States. Our findings suggest that a long-term trajectory can be

  15. Chaotic itinerancy and power-law residence time distribution in stochastic dynamical systems.

    Science.gov (United States)

    Namikawa, Jun

    2005-08-01

    Chaotic itinerant motion among varieties of ordered states is described by a stochastic model based on the mechanism of chaotic itinerancy. The model consists of a random walk on a half-line and a Markov chain with a transition probability matrix. The stability of attractor ruin in the model is investigated by analyzing the residence time distribution of orbits at attractor ruins. It is shown that the residence time distribution averaged over all attractor ruins can be described by the superposition of (truncated) power-law distributions if the basin of attraction for each attractor ruin has a zero measure. This result is confirmed by simulation of models exhibiting chaotic itinerancy. Chaotic itinerancy is also shown to be absent in coupled Milnor attractor systems if the transition probability among attractor ruins can be represented as a Markov chain.

  16. Influence of instantaneous and time-averaged groundwater flows induced by waves on the fate of contaminants in a beach aquifer

    Science.gov (United States)

    Malott, Spencer; O'Carroll, Denis M.; Robinson, Clare E.

    2017-09-01

    Wave-induced water exchange and groundwater flows in beach aquifers impact the fate of contaminants including nutrients, fecal bacteria, and nonaqueous phase liquids (NAPLs). Waves induce high-frequency fluxes in shallow beach sediments. In addition, the phase-averaged effect of waves (wave setup) drives deeper flow recirculations through a beach aquifer. Field data of shallow instantaneous and time-averaged vertical head gradients (fluxes) are first compared with deeper time-averaged fluxes over a period of varying wave conditions. The time-averaged fluxes are equivalent to that which would be simulated assuming a phase-averaged water surface (i.e., wave setup). Based on this comparison, the need to simulate phase-resolved wave motion versus the simplified phase-averaged water surface in predicting contaminant fate is evaluated. While high-frequency fluxes cause large surface water volumes to filter through beach sediments, the exchanging water has a short residence time (colloidal contaminants (e.g., particulate organic matter and fecal bacteria) as sediment interactions affect their transport and residence time. Finally, multiphase simulations illustrate the differential effect of considering instantaneous versus time-averaged fluxes on the downward migration of NAPL in beach sediments. This study provides an important foundation for future field and modeling efforts focused on understanding and predicting contaminant transport in wave-influenced beaches.

  17. A RED modified weighted moving average for soft real-time application

    Directory of Open Access Journals (Sweden)

    Domanśka Joanna

    2014-09-01

    Full Text Available The popularity of TCP/IP has resulted in an increase in usage of best-effort networks for real-time communication. Much effort has been spent to ensure quality of service for soft real-time traffic over IP networks. The Internet Engineering Task Force has proposed some architecture components, such as Active Queue Management (AQM. The paper investigates the influence of the weighted moving average on packet waiting time reduction for an AQM mechanism: the RED algorithm. The proposed method for computing the average queue length is based on a difference equation (a recursive equation. Depending on a particular optimality criterion, proper parameters of the modified weighted moving average function can be chosen. This change will allow reducing the number of violations of timing constraints and better use of this mechanism for soft real-time transmissions. The optimization problem is solved through simulations performed in OMNeT++ and later verified experimentally on a Linux implementation

  18. Mean Transit Time and Mean Residence Time for Linear Diffusion–Convection–Reaction Transport System

    Directory of Open Access Journals (Sweden)

    Jacek Waniewski

    2007-01-01

    Full Text Available Characteristic times for transport processes in biological systems may be evaluated as mean transit times (MTTs (for transit states or mean residence times (MRT (for steady states. It is shown in a general framework of a (linear reaction–diffusion–convection equation that these two times are related. Analytical formulas are also derived to calculate moments of exit time distribution using solutions for a stationary state of the system.

  19. Modeling an Application's Theoretical Minimum and Average Transactional Response Times

    Energy Technology Data Exchange (ETDEWEB)

    Paiz, Mary Rose [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-04-01

    The theoretical minimum transactional response time of an application serves as a ba- sis for the expected response time. The lower threshold for the minimum response time represents the minimum amount of time that the application should take to complete a transaction. Knowing the lower threshold is beneficial in detecting anomalies that are re- sults of unsuccessful transactions. On the converse, when an application's response time falls above an upper threshold, there is likely an anomaly in the application that is causing unusual performance issues in the transaction. This report explains how the non-stationary Generalized Extreme Value distribution is used to estimate the lower threshold of an ap- plication's daily minimum transactional response time. It also explains how the seasonal Autoregressive Integrated Moving Average time series model is used to estimate the upper threshold for an application's average transactional response time.

  20. Residence Time Distributions in a Cold, Confined Swirl Flow

    DEFF Research Database (Denmark)

    Lans, Robert Pieter Van Der; Glarborg, Peter; Dam-Johansen, Kim

    1997-01-01

    -burner zone of the laboratory furnace-model were studied. RTD results have been used to derive a chemical reaction engineering model for the mixing process. The model is based on a combination of plug flow reactors and continuous stirred tank reactors, which represent the main flow characteristics in regard......, well characterised flow pattern makes it possible to investigate the importance of mixing intensity on the (pollution) chemistry in furnaces. The reactor model developed here will be the basis for the development of a chemical reaction engineering combustion model.......Residence time distributions (RTD) in a confined, cold swirling flow have been measured with a fast-response probe and helium as a tracer. The test-rig represented a scaled down version of a burner. The effect of variation of flow velocities and swirl angle on the flow pattern in the near...

  1. Impact of connected vehicle guidance information on network-wide average travel time

    Directory of Open Access Journals (Sweden)

    Jiangfeng Wang

    2016-12-01

    Full Text Available With the emergence of connected vehicle technologies, the potential positive impact of connected vehicle guidance on mobility has become a research hotspot by data exchange among vehicles, infrastructure, and mobile devices. This study is focused on micro-modeling and quantitatively evaluating the impact of connected vehicle guidance on network-wide travel time by introducing various affecting factors. To evaluate the benefits of connected vehicle guidance, a simulation architecture based on one engine is proposed representing the connected vehicle–enabled virtual world, and connected vehicle route guidance scenario is established through the development of communication agent and intelligent transportation systems agents using connected vehicle application programming interface considering the communication properties, such as path loss and transmission power. The impact of connected vehicle guidance on network-wide travel time is analyzed by comparing with non-connected vehicle guidance in response to different market penetration rate, following rate, and congestion level. The simulation results explore that average network-wide travel time in connected vehicle guidance shows a significant reduction versus that in non–connected vehicle guidance. Average network-wide travel time in connected vehicle guidance have an increase of 42.23% comparing to that in non-connected vehicle guidance, and average travel time variability (represented by the coefficient of variance increases as the travel time increases. Other vital findings include that higher penetration rate and following rate generate bigger savings of average network-wide travel time. The savings of average network-wide travel time increase from 17% to 38% according to different congestion levels, and savings of average travel time in more serious congestion have a more obvious improvement for the same penetration rate or following rate.

  2. Thermal motion in proteins: Large effects on the time-averaged interaction energies

    Energy Technology Data Exchange (ETDEWEB)

    Goethe, Martin, E-mail: martingoethe@ub.edu; Rubi, J. Miguel [Departament de Física Fonamental, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain); Fita, Ignacio [Institut de Biologia Molecular de Barcelona, Baldiri Reixac 10, 08028 Barcelona (Spain)

    2016-03-15

    As a consequence of thermal motion, inter-atomic distances in proteins fluctuate strongly around their average values, and hence, also interaction energies (i.e. the pair-potentials evaluated at the fluctuating distances) are not constant in time but exhibit pronounced fluctuations. These fluctuations cause that time-averaged interaction energies do generally not coincide with the energy values obtained by evaluating the pair-potentials at the average distances. More precisely, time-averaged interaction energies behave typically smoother in terms of the average distance than the corresponding pair-potentials. This averaging effect is referred to as the thermal smoothing effect. Here, we estimate the strength of the thermal smoothing effect on the Lennard-Jones pair-potential for globular proteins at ambient conditions using x-ray diffraction and simulation data of a representative set of proteins. For specific atom species, we find a significant smoothing effect where the time-averaged interaction energy of a single atom pair can differ by various tens of cal/mol from the Lennard-Jones potential at the average distance. Importantly, we observe a dependency of the effect on the local environment of the involved atoms. The effect is typically weaker for bulky backbone atoms in beta sheets than for side-chain atoms belonging to other secondary structure on the surface of the protein. The results of this work have important practical implications for protein software relying on free energy expressions. We show that the accuracy of free energy expressions can largely be increased by introducing environment specific Lennard-Jones parameters accounting for the fact that the typical thermal motion of protein atoms depends strongly on their local environment.

  3. The Seasonality in the Number of Overnight Stays by Residents in Romania and Bulgaria and Its Ranking in Connection to the EU Average Level

    Directory of Open Access Journals (Sweden)

    Aivaz Kamer Ainur

    2017-01-01

    For the purpose of our quantitative research, we processed a database comprised of the monthly values of the "total number of overnight stays by residents", recorded from January 2005 to December 2016, using the moving average method and the seasonality coefficient. We believe that this information may be especially useful to the decision-makers of the Romanian tourism activity in the conception of the tourism development strategy.

  4. Parameterization of Time-Averaged Suspended Sediment Concentration in the Nearshore

    Directory of Open Access Journals (Sweden)

    Hyun-Doug Yoon

    2015-11-01

    Full Text Available To quantify the effect of wave breaking turbulence on sediment transport in the nearshore, the vertical distribution of time-averaged suspended sediment concentration (SSC in the surf zone was parameterized in terms of the turbulent kinetic energy (TKE at different cross-shore locations, including the bar crest, bar trough, and inner surf zone. Using data from a large-scale laboratory experiment, a simple relationship was developed between the time-averaged SSC and the time-averaged TKE. The vertical variation of the time-averaged SSC was fitted to an equation analogous to the turbulent dissipation rate term. At the bar crest, the proposed equation was slightly modified to incorporate the effect of near-bed sediment processes and yielded reasonable agreement. This parameterization yielded the best agreement at the bar trough, with a coefficient of determination R2 ≥ 0.72 above the bottom boundary layer. The time-averaged SSC in the inner surf zone showed good agreement near the bed but poor agreement near the water surface, suggesting that there is a different sedimentation mechanism that controls the SSC in the inner surf zone.

  5. Extension of the time-average model to Candu refueling schemes involving reshuffling

    International Nuclear Information System (INIS)

    Rouben, Benjamin; Nichita, Eleodor

    2008-01-01

    Candu reactors consist of a horizontal non-pressurized heavy-water-filled vessel penetrated axially by fuel channels, each containing twelve 50-cm-long fuel bundles cooled by pressurized heavy water. Candu reactors are refueled on-line and, as a consequence, the core flux and power distributions change continuously. For design purposes, a 'time-average' model was developed in the 1970's to calculate the average over time of the flux and power distribution and to study the effects of different refueling schemes. The original time-average model only allows treatment of simple push-through refueling schemes whereby fresh fuel is inserted at one end of the channel and irradiated fuel is removed from the other end. With the advent of advanced fuel cycles and new Candu designs, novel refueling schemes may be considered, such as reshuffling discharged fuel from some channels into other channels, to achieve better overall discharge burnup. Such reshuffling schemes cannot be handled by the original time-average model. This paper presents an extension of the time-average model to allow for the treatment of refueling schemes with reshuffling. Equations for the extended model are presented, together with sample results for a simple demonstration case. (authors)

  6. Residence time of contaminants released in surface coal mines: A wind-tunnel study

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, R.S.

    1993-08-01

    The 1990 Clean Air Act Amendments direct the U.S. Environmental Protection Agency to evaluate and modify, as required, existing dispersion models for the prediction of dispersion of dust from surface coal mines. The application of mathematical air pollution dispersion models to the dispersion of dust from surface coal mines requires knowledge of not only the amount of dust generated in the mine, but the fraction of that generated that actually escapes from the mine. The escape fraction can be related to the residence time that released material will remain, on average, within the mine. The concentration in the mine was found to follow an exponential decay function from which an exponential decay time constant (or residence time) was computed for each case. A semi-empirical formula was found that related the residence time to the mine geometry and wind direction quite well. This formula can be used to estimate escape fraction in determining the source strength for the application of mathematical dispersion models.

  7. On-site residence time in a driven diffusive system: Violation and recovery of a mean-field description.

    Science.gov (United States)

    Messelink, J; Rens, R; Vahabi, M; MacKintosh, F C; Sharma, A

    2016-01-01

    We investigate simple one-dimensional driven diffusive systems with open boundaries. We are interested in the average on-site residence time defined as the time a particle spends on a given site before moving on to the next site. Using mean-field theory, we obtain an analytical expression for the on-site residence times. By comparing the analytic predictions with numerics, we demonstrate that the mean-field significantly underestimates the residence time due to the neglect of time correlations in the local density of particles. The temporal correlations are particularly long-lived near the average shock position, where the density changes abruptly from low to high. By using domain wall theory, we obtain highly accurate estimates of the residence time for different boundary conditions. We apply our analytical approach to residence times in a totally asymmetric exclusion process (TASEP), TASEP coupled to Langmuir kinetics (TASEP+LK), and TASEP coupled to mutually interactive LK (TASEP+MILK). The high accuracy of our predictions is verified by comparing these with detailed Monte Carlo simulations.

  8. Optimal bounds and extremal trajectories for time averages in nonlinear dynamical systems

    Science.gov (United States)

    Tobasco, Ian; Goluskin, David; Doering, Charles R.

    2018-02-01

    For any quantity of interest in a system governed by ordinary differential equations, it is natural to seek the largest (or smallest) long-time average among solution trajectories, as well as the extremal trajectories themselves. Upper bounds on time averages can be proved a priori using auxiliary functions, the optimal choice of which is a convex optimization problem. We prove that the problems of finding maximal trajectories and minimal auxiliary functions are strongly dual. Thus, auxiliary functions provide arbitrarily sharp upper bounds on time averages. Moreover, any nearly minimal auxiliary function provides phase space volumes in which all nearly maximal trajectories are guaranteed to lie. For polynomial equations, auxiliary functions can be constructed by semidefinite programming, which we illustrate using the Lorenz system.

  9. Numerical modeling of general circulation, thermohaline structure, and residence time in Gorgan Bay, Iran

    Science.gov (United States)

    Ranjbar, Mohammad Hassan; Hadjizadeh Zaker, Nasser

    2018-01-01

    Gorgan Bay is a semi-enclosed basin located in the southeast of the Caspian Sea, Iran. The bay is recognized as a resting place for migratory birds as well as a spawning habitat for native fish. However, apparently, no detailed research on its physical processes has previously been conducted. In this study, a 3D coupled hydrodynamic and solute transport model was used to investigate general circulation, thermohaline structure, and residence time in Gorgan Bay. Model outputs were validated against a set of field observations. Bottom friction and attenuation coefficient of light intensity were tuned in order to achieve optimum agreement with the observations. Results revealed that, due to the interaction between bathymetry and prevailing winds, a barotropic double-gyre circulation, dominating the general circulation, existed during all seasons in Gorgan Bay. Furthermore, temperature and salinity fluctuations in the bay were seasonal, due to the seasonal variability of atmospheric fluxes. Results also indicated that under the prevailing winds, the domain-averaged residence time in Gorgan Bay would be approximately 95 days. The rivers discharging into Gorgan Bay are considered as the main sources of nutrients in the bay. Since their mouths are located in the area with a residence time of over 100 days, Gorgan Bay could be at risk of eutrophication; it is necessary to adopt preventive measures against water quality degradation.

  10. New residence times of the Holocene reworked shells on the west coast of Bohai Bay, China

    Science.gov (United States)

    Shang, Zhiwen; Wang, Fu; Li, Jianfen; Marshall, William A.; Chen, Yongsheng; Jiang, Xingyu; Tian, Lizhu; Wang, Hong

    2016-01-01

    Shelly cheniers and shell-rich beds found intercalated in near-shore marine muds and sandy sediments can be used to indicate the location of ancient shorelines, and help to estimate the height of sea level. However, dating the deposition of material within cheniers and shell-rich beds is not straightforward because much of this material is transported and re-worked, creating an unknown temporal off-set, i.e., the residence time, between the death of a shell and its subsequent entombment. To quantify the residence time during the Holocene on a section of the northern Chinese coastline a total 47 shelly subsamples were taken from 17 discrete layers identified on the west coast of Bohai Bay. This material was AMS 14C dated and the calibrated ages were systematically compared. The subsamples were categorized by type as articulated and disarticulated bivalves, gastropod shells, and undifferentiated shell-hash. It was found that within most individual layers the calibrated ages of the subsamples got younger relative to the amount of apparent post-mortem re-working the material had been subject to. For examples, the 14C ages of the bivalve samples trended younger in this order: shell-hash → split shells → articulated shells. We propose that the younger subsample age determined within an individual layer will be the closest to the actual depositional age of the material dated. Using this approach at four Holocene sites we find residence times which range from 100 to 1260 cal yrs, with two average values of 600 cal yrs for the original 14C dates older than 1 ka cal BP and 100 cal yrs for the original 14C dates younger than 1 ka cal BP, respectively. Using this semi-empirical estimation of the shell residence times we have refined the existing chronology of the Holocene chenier ridges on the west coast of Bohai Bay.

  11. High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: influence of contaminated fish consumption.

    Science.gov (United States)

    Lee, C C; Lin, W T; Liao, P C; Su, H J; Chen, H L

    2006-05-01

    An abandoned pentachlorophenol plant and nearby area in southern Taiwan was heavily contaminated by dioxins, impurities formed in the PCP production process. The investigation showed that the average serum PCDD/Fs of residents living nearby area (62.5 pg WHO-TEQ/g lipid) was higher than those living in the non-polluted area (22.5 and 18.2 pg WHO-TEQ/g lipid) (Pfarm (0.15 pg WHO-TEQ/g), and Tilapia and shrimp showed the similar trend. The average daily PCDD/Fs intake of 38% participants was higher than 4 pg WHO-TEQ/kg/day suggested by the world health organization. Serum PCDD/F was positively associated with average daily intake (ADI) after adjustment for age, sex, BMI, and smoking status. In addition, a prospective cohort study is suggested to determine the long-term health effects on the people living near factory.

  12. Constrained Optimization of Average Arrival Time via a Probabilistic Approach to Transport Reliability.

    Directory of Open Access Journals (Sweden)

    Mohammad-Reza Namazi-Rad

    Full Text Available To achieve greater transit-time reduction and improvement in reliability of transport services, there is an increasing need to assist transport planners in understanding the value of punctuality; i.e. the potential improvements, not only to service quality and the consumer but also to the actual profitability of the service. In order for this to be achieved, it is important to understand the network-specific aspects that affect both the ability to decrease transit-time, and the associated cost-benefit of doing so. In this paper, we outline a framework for evaluating the effectiveness of proposed changes to average transit-time, so as to determine the optimal choice of average arrival time subject to desired punctuality levels whilst simultaneously minimizing operational costs. We model the service transit-time variability using a truncated probability density function, and simultaneously compare the trade-off between potential gains and increased service costs, for several commonly employed cost-benefit functions of general form. We formulate this problem as a constrained optimization problem to determine the optimal choice of average transit time, so as to increase the level of service punctuality, whilst simultaneously ensuring a minimum level of cost-benefit to the service operator.

  13. Pathology residency training: time for a new paradigm.

    Science.gov (United States)

    Domen, Ronald E; Baccon, Jennifer

    2014-06-01

    The exponential growth of the field of pathology over the past several decades has created challenges for residency training programs. These challenges include the ability to train competent pathologists in 4 years, an increased demand for fellowship training, and the structuring and completion of maintenance of certification. The authors feel that pathology residency training has reached a critical point and that a new paradigm for training is required. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. The role of topography on catchment‐scale water residence time

    Science.gov (United States)

    McGuire, K.J.; McDonnell, Jeffery J.; Weiler, M.; Kendall, C.; McGlynn, B.L.; Welker, J.M.; Seibert, J.

    2005-01-01

    The age, or residence time, of water is a fundamental descriptor of catchment hydrology, revealing information about the storage, flow pathways, and source of water in a single integrated measure. While there has been tremendous recent interest in residence time estimation to characterize watersheds, there are relatively few studies that have quantified residence time at the watershed scale, and fewer still that have extended those results beyond single catchments to larger landscape scales. We examined topographic controls on residence time for seven catchments (0.085–62.4 km2) that represent diverse geologic and geomorphic conditions in the western Cascade Mountains of Oregon. Our primary objective was to determine the dominant physical controls on catchment‐scale water residence time and specifically test the hypothesis that residence time is related to the size of the basin. Residence times were estimated by simple convolution models that described the transfer of precipitation isotopic composition to the stream network. We found that base flow mean residence times for exponential distributions ranged from 0.8 to 3.3 years. Mean residence time showed no correlation to basin area (r2 organization (i.e., topography) rather than basin area controls catchment‐scale transport. Results from this study may provide a framework for describing scale‐invariant transport across climatic and geologic conditions, whereby the internal form and structure of the basin defines the first‐order control on base flow residence time.

  15. On the time-averaging of ultrafine particle number size spectra in vehicular plumes

    Directory of Open Access Journals (Sweden)

    X. H. Yao

    2006-01-01

    Full Text Available Ultrafine vehicular particle (<100 nm number size distributions presented in the literature are mostly averages of long scan-time (~30 s or more spectra mainly due to the non-availability of commercial instruments that can measure particle distributions in the <10 nm to 100 nm range faster than 30 s even though individual researchers have built faster (1–2.5 s scanning instruments. With the introduction of the Engine Exhaust Particle Sizer (EEPS in 2004, high time-resolution (1 full 32-channel spectrum per second particle size distribution data become possible and allow atmospheric researchers to study the characteristics of ultrafine vehicular particles in rapidly and perhaps randomly varying high concentration environments such as roadside, on-road and tunnel. In this study, particle size distributions in these environments were found to vary as rapidly as one second frequently. This poses the question on the generality of using averages of long scan-time spectra for dynamic and/or mechanistic studies in rapidly and perhaps randomly varying high concentration environments. One-second EEPS data taken at roadside, on roads and in tunnels by a mobile platform are time-averaged to yield 5, 10, 30 and 120 s distributions to answer this question.

  16. Online Self-Organizing Network Control with Time Averaged Weighted Throughput Objective

    Directory of Open Access Journals (Sweden)

    Zhicong Zhang

    2018-01-01

    Full Text Available We study an online multisource multisink queueing network control problem characterized with self-organizing network structure and self-organizing job routing. We decompose the self-organizing queueing network control problem into a series of interrelated Markov Decision Processes and construct a control decision model for them based on the coupled reinforcement learning (RL architecture. To maximize the mean time averaged weighted throughput of the jobs through the network, we propose a reinforcement learning algorithm with time averaged reward to deal with the control decision model and obtain a control policy integrating the jobs routing selection strategy and the jobs sequencing strategy. Computational experiments verify the learning ability and the effectiveness of the proposed reinforcement learning algorithm applied in the investigated self-organizing network control problem.

  17. High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: Influence of contaminated fish consumption

    International Nuclear Information System (INIS)

    Lee, C.C.; Lin, W.T.; Liao, P.C.; Su, H.J.; Chen, H.L.

    2006-01-01

    An abandoned pentachlorophenol plant and nearby area in southern Taiwan was heavily contaminated by dioxins, impurities formed in the PCP production process. The investigation showed that the average serum PCDD/Fs of residents living nearby area (62.5 pg WHO-TEQ/g lipid) was higher than those living in the non-polluted area (22.5 and 18.2 pg WHO-TEQ/g lipid) (P < 0.05). In biota samples, average PCDD/F of milkfish in sea reservoir (28.3 pg WHO-TEQ/g) was higher than those in the nearby fish farm (0.15 pg WHO-TEQ/g), and Tilapia and shrimp showed the similar trend. The average daily PCDD/Fs intake of 38% participants was higher than 4 pg WHO-TEQ/kg/day suggested by the world health organization. Serum PCDD/F was positively associated with average daily intake (ADI) after adjustment for age, sex, BMI, and smoking status. In addition, a prospective cohort study is suggested to determine the long-term health effects on the people living near factory. - Inhabitants living near a deserted PCP factory are exposed to high PCDD/F levels

  18. High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: Influence of contaminated fish consumption

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.C. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Research Center of Environmental Trace Toxic Substances, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Lin, W.T. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Liao, P.C. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Research Center of Environmental Trace Toxic Substances, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Su, H.J. [Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Research Center of Environmental Trace Toxic Substances, Medical College, National Cheng Kung University, Tainan, Taiwan (China); Chen, H.L. [Department of Industrial Safety and Health, Hung Kuang University, Taichung, 34 Chung Chie Rd. Sha Lu, Taichung 433, Taiwan (China)]. E-mail: hsiulin@sunrise.hk.edu.tw

    2006-05-15

    An abandoned pentachlorophenol plant and nearby area in southern Taiwan was heavily contaminated by dioxins, impurities formed in the PCP production process. The investigation showed that the average serum PCDD/Fs of residents living nearby area (62.5 pg WHO-TEQ/g lipid) was higher than those living in the non-polluted area (22.5 and 18.2 pg WHO-TEQ/g lipid) (P < 0.05). In biota samples, average PCDD/F of milkfish in sea reservoir (28.3 pg WHO-TEQ/g) was higher than those in the nearby fish farm (0.15 pg WHO-TEQ/g), and Tilapia and shrimp showed the similar trend. The average daily PCDD/Fs intake of 38% participants was higher than 4 pg WHO-TEQ/kg/day suggested by the world health organization. Serum PCDD/F was positively associated with average daily intake (ADI) after adjustment for age, sex, BMI, and smoking status. In addition, a prospective cohort study is suggested to determine the long-term health effects on the people living near factory. - Inhabitants living near a deserted PCP factory are exposed to high PCDD/F levels.

  19. Gearbox fault diagnosis based on time-frequency domain synchronous averaging and feature extraction technique

    Science.gov (United States)

    Zhang, Shengli; Tang, Jiong

    2016-04-01

    Gearbox is one of the most vulnerable subsystems in wind turbines. Its healthy status significantly affects the efficiency and function of the entire system. Vibration based fault diagnosis methods are prevalently applied nowadays. However, vibration signals are always contaminated by noise that comes from data acquisition errors, structure geometric errors, operation errors, etc. As a result, it is difficult to identify potential gear failures directly from vibration signals, especially for the early stage faults. This paper utilizes synchronous averaging technique in time-frequency domain to remove the non-synchronous noise and enhance the fault related time-frequency features. The enhanced time-frequency information is further employed in gear fault classification and identification through feature extraction algorithms including Kernel Principal Component Analysis (KPCA), Multilinear Principal Component Analysis (MPCA), and Locally Linear Embedding (LLE). Results show that the LLE approach is the most effective to classify and identify different gear faults.

  20. On the XFEL Schrödinger Equation: Highly Oscillatory Magnetic Potentials and Time Averaging

    KAUST Repository

    Antonelli, Paolo

    2014-01-14

    We analyse a nonlinear Schrödinger equation for the time-evolution of the wave function of an electron beam, interacting selfconsistently through a Hartree-Fock nonlinearity and through the repulsive Coulomb interaction of an atomic nucleus. The electrons are supposed to move under the action of a time dependent, rapidly periodically oscillating electromagnetic potential. This can be considered a simplified effective single particle model for an X-ray free electron laser. We prove the existence and uniqueness for the Cauchy problem and the convergence of wave-functions to corresponding solutions of a Schrödinger equation with a time-averaged Coulomb potential in the high frequency limit for the oscillations of the electromagnetic potential. © 2014 Springer-Verlag Berlin Heidelberg.

  1. Past Negative Time Perspective as a Predictor of Grade Point Average in Occupational Therapy Doctoral Students

    Directory of Open Access Journals (Sweden)

    Pat J. Precin

    2017-05-01

    Full Text Available Time perspective is a fundamental dimension in psychological time, dividing human experiences into past, present, and future. Time perspective influences individuals’ functioning in all occupations, including education. Previous research has examined the relationship between time perspective and academic outcomes, but the same research has not been done, to date, with occupational therapy doctoral students. This quantitative, cross-sectional study investigated the relationship between time perspective and academic success in occupational therapy doctoral students across the United States. Data from the Zimbardo Time Perspective Inventory (ZTPI and grade point averages (GPAs were collected from 50 participants via surveymonkey.com. Past Negative time perspective statistically predicted GPA in the negative direction (p = .001 for students in pre-professional OTD programs, but did not predict GPA for post-professional students. Age, gender, and learning environment did not significantly influence the prediction of GPA in either group. The method and results of this study demonstrate that the ZTPI, an instrument used in the field of psychology, may have value in the profession of occupational therapy and occupational therapy doctoral programs.

  2. Time Average Holography Study of Human Tympanic Membrane with Altered Middle Ear Ossicular Chain

    Science.gov (United States)

    Cheng, Jeffrey T.; Ravicz, Michael E.; Rosowski, John J.; Hulli, Nesim; Hernandez-Montes, Maria S.; Furlong, Cosme

    2009-02-01

    Computer-assisted time average holographic interferometry was used to study the vibration of the human tympanic membrane (TM) in cadaveric temporal bones before and after alterations of the ossicular chain. Simultaneous laser Doppler vibrometer measurements of stapes velocity were performed to estimate the conductive hearing loss caused by ossicular alterations. The quantified TM motion described from holographic images was correlated with stapes velocity to define relations between TM motion and stapes velocity in various ossicular disorders. The results suggest that motions of the TM are relatively uncoupled from stapes motion at frequencies above 1000 Hz.

  3. Numerical and machine learning simulation of parametric distributions of groundwater residence time in streams and wells

    Science.gov (United States)

    Starn, J. J.; Belitz, K.; Carlson, C.

    2017-12-01

    Groundwater residence-time distributions (RTDs) are critical for assessing susceptibility of water resources to contamination. This novel approach for estimating regional RTDs was to first simulate groundwater flow using existing regional digital data sets in 13 intermediate size watersheds (each an average of 7,000 square kilometers) that are representative of a wide range of glacial systems. RTDs were simulated with particle tracking. We refer to these models as "general models" because they are based on regional, as opposed to site-specific, digital data. Parametric RTDs were created from particle RTDs by fitting 1- and 2-component Weibull, gamma, and inverse Gaussian distributions, thus reducing a large number of particle travel times to 3 to 7 parameters (shape, location, and scale for each component plus a mixing fraction) for each modeled area. The scale parameter of these distributions is related to the mean exponential age; the shape parameter controls departure from the ideal exponential distribution and is partly a function of interaction with bedrock and with drainage density. Given the flexible shape and mathematical similarity of these distributions, any of them are potentially a good fit to particle RTDs. The 1-component gamma distribution provided a good fit to basin-wide particle RTDs. RTDs at monitoring wells and streams often have more complicated shapes than basin-wide RTDs, caused in part by heterogeneity in the model, and generally require 2-component distributions. A machine learning model was trained on the RTD parameters using features derived from regionally available watershed characteristics such as recharge rate, material thickness, and stream density. RTDs appeared to vary systematically across the landscape in relation to watershed features. This relation was used to produce maps of useful metrics with respect to risk-based thresholds, such as the time to first exceedance, time to maximum concentration, time above the threshold

  4. Variability in benthic exchange rate, depth, and residence time beneath a shallow coastal estuary

    Science.gov (United States)

    Russoniello, C. J.; Michael, H. A.; Heiss, J.

    2017-12-01

    Hydrodynamically-driven exchange of water between the water column and shallow seabed aquifer, benthic exchange, is a significant and dynamic component of coastal and estuarine fluid budgets, but wave-induced benthic exchange has not been measured in the field. Mixing between surface water and groundwater solutes promotes ecologically important chemical reactions, so quantifying benthic exchange rates, depths, and residence times, constrains estimates of coastal chemical cycling. In this study, we present the first field-based direct measurements of wave-induced exchange and compare it to exchange induced by the other primary drivers of exchange - tides, and currents. We deployed instruments in a shallow estuary to measure benthic exchange and temporal variability over an 11-day period. Differential pressure sensors recorded pressure gradients across the seabed, and up-and down-looking ADCPs recorded currents and pressures from which wave parameters, surface-water currents, and water depth were determined. Wave-induced exchange was calculated directly from 1) differential pressure measurements, and indirectly with an analytical solution based on wave parameters from 2) ADCP and 3) weather station data. Groundwater flow models were used to assess the effects of aquifer properties on benthic exchange depth and residence time. Benthic exchange driven by tidal pumping or current-bedform interaction was calculated from tidal stage variation and from ADCP-measured currents at the bed, respectively. Waves were the primary benthic exchange driver (average = 20.0 cm/d, maximum = 92.3 cm/d) during the measurement period. Benthic exchange due to tides (average = 3.7 cm/d) and current-bedform interaction (average = 6.5x10-2 cm/d) was much lower. Wave-induced exchange calculated from pressure measurements and ADCP-measured wave parameters matched well, but wind-based rates underestimated wave energy and exchange. Groundwater models showed that residence time and depth increased

  5. Effects of zebra mussels on food webs: Interactions with juvenile bluegill and water residence time

    Science.gov (United States)

    Richardson, W.B.; Bartsch, L.A.

    1997-01-01

    We evaluated how water residence time mediated the impact of zebra mussels Dreissena polymorpha and bluegill sunfish Lepomis macrochirus on experimental food webs established in 1100-1 outdoor mesocosms. Water residence time was manipulated as a surrogate for seston resupply - a critical variable affecting growth and survival of suspension-feeding invertebrates. We used a 2 x 2 x 2 factorial experimental design with eight treatment combinations (3 replicates/treatment) including the presence or absence of Dreissena (2000 per m2), juvenile bluegill (40 per mesocosm), and short (1100 1 per d) or long (220 1 per d) water residence time. Measures of seston concentration (chlorophyll a, turbidity and suspended solids) were greater in the short- compared to long water-residence mesocosms, but intermediate in short water-residence mesocosms containing Dreissena. Abundance of rotifers (Keratella and Polyarthra) was reduced in Dreissena mesocosms and elevated in short residence time mesocosms. Cladocera abundance, in general, was unaffected by the presence of Dreissena; densities were higher in short-residence time mesocosms, and reduced in the presence of Lepomis. The growth of juvenile Lepomis were unaffected by Dreissena because of abundant benthic food. The final total mass of Dreissena was significantly greater in short- than long-residence mesocosms. Impacts of Dreissena on planktonic food webs may not only depend on the density of zebra mussels but also on the residence time of the surrounding water and the resupply of seston. ?? 1997 Kluwer Academic Publishers.

  6. Force production and time-averaged flow structure around thin, non-slender delta wings

    Science.gov (United States)

    Tu, Han; Green, Melissa

    2017-11-01

    Experimental force measurement and time-averaged three dimensional flow visualization of low Reynolds number baseline cases have been carried out on a steady flat plate delta wing. Current data will serve as steady reference for future unsteady flow and actuation cases. The comprehensive study will compare force production in highly unsteady environments, which is necessary to consider in unmanned combat aerial vehicle (UCAV) control strategies. Force measurements are carried out at angles of attack 10, 15, 20, 25 and 30 degrees. The coefficient of drag increases with angle of attack, while the coefficient of lift reaches a maximum value at 20 degrees. Time-averaged flow visualization conducted at angles of attack of 20, 25 and 30 degrees shows vortices with larger magnitude that persist farther into wake are generated at higher angles of attack. These results compare analogously with similar steady baseline experiment results of high Reynolds number conducted by collaborators. This work was supported by the Office of Naval Research under ONR Award No. N00014-16-1-2732. We also acknowledge the collaborative support of Dr. David Rival and Mr. Matthew Marzanek at Queen's University.

  7. Image encryption scheme based on computer generated holography and time-averaged moiré

    Science.gov (United States)

    Palevicius, Paulius; Ragulskis, Minvydas; Janusas, Giedrius; Palevicius, Arvydas

    2017-08-01

    A technique of computational image encryption and optical decryption based on computer generated holography and time-averaged moiŕe is investigated in this paper. Dynamic visual cryptography (a visual cryptography scheme based on time-averaging geometric moiŕe), Gerchberg-Saxton algorithm and 3D microstructure manufacturing techniques are used to construct the optical scheme. The secret is embedded into a cover image by using a stochastic moiŕe grating and can be visually decoded by a naked eye. The secret is revealed if the amplitude of harmonic oscillations in the Fourier plane corresponds to an accurately preselected value. The process of the production of 3D microstructure is described in details. Computer generated holography is used in the design step and electron beam lithography is exploited for physical 3D patterning. The phase data of a complex 3D microstructure is obtained by Gerchberg-Saxton algorithm and is used to produce a computer generated hologram. Physical implementation of microstructure is performed by using a single layer polymethyl methacrylate as a basis for 3D microstructure. Numerical simulations demonstrate efficient applicability of this technique.

  8. Enhancing MALDI time-of-flight mass spectrometer performance through spectrum averaging.

    Science.gov (United States)

    Mitchell, Morgan; Mali, Sujina; King, Charles C; Bark, Steven J

    2015-01-01

    Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometers are simple and robust mass spectrometers used for analysis of biologically relevant molecules in diverse fields including pathogen identification, imaging mass spectrometry, and natural products chemistry. Despite high nominal resolution and accuracy, we have observed significant variability where 30-50% of individual replicate measurements have errors in excess of 5 parts-per-million, even when using 5-point internal calibration. Increasing the number of laser shots for each spectrum did not resolve this observed variability. What is responsible for our observed variation? Using a modern MALDI-TOF/TOF instrument, we evaluated contributions to variability. Our data suggest a major component of variability is binning of the raw flight time data by the electronics and clock speed of the analog-to-digital (AD) detection system, which requires interpolation by automated peak fitting algorithms and impacts both calibration and the observed mass spectrum. Importantly, the variation observed is predominantly normal in distribution, which implies multiple components contribute to the observed variation and suggests a method to mitigate this variability through spectrum averaging. Restarting the acquisition impacts each spectrum within the electronic error of the AD detector system and defines a new calibration function. Therefore, averaging multiple independent spectra and not a larger number of laser shots leverages this inherent binning error to mitigate variability in accurate MALDI-TOF mass measurements.

  9. Enhancing MALDI time-of-flight mass spectrometer performance through spectrum averaging.

    Directory of Open Access Journals (Sweden)

    Morgan Mitchell

    Full Text Available Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF mass spectrometers are simple and robust mass spectrometers used for analysis of biologically relevant molecules in diverse fields including pathogen identification, imaging mass spectrometry, and natural products chemistry. Despite high nominal resolution and accuracy, we have observed significant variability where 30-50% of individual replicate measurements have errors in excess of 5 parts-per-million, even when using 5-point internal calibration. Increasing the number of laser shots for each spectrum did not resolve this observed variability. What is responsible for our observed variation? Using a modern MALDI-TOF/TOF instrument, we evaluated contributions to variability. Our data suggest a major component of variability is binning of the raw flight time data by the electronics and clock speed of the analog-to-digital (AD detection system, which requires interpolation by automated peak fitting algorithms and impacts both calibration and the observed mass spectrum. Importantly, the variation observed is predominantly normal in distribution, which implies multiple components contribute to the observed variation and suggests a method to mitigate this variability through spectrum averaging. Restarting the acquisition impacts each spectrum within the electronic error of the AD detector system and defines a new calibration function. Therefore, averaging multiple independent spectra and not a larger number of laser shots leverages this inherent binning error to mitigate variability in accurate MALDI-TOF mass measurements.

  10. Observer design for switched recurrent neural networks: an average dwell time approach.

    Science.gov (United States)

    Lian, Jie; Feng, Zhi; Shi, Peng

    2011-10-01

    This paper is concerned with the problem of observer design for switched recurrent neural networks with time-varying delay. The attention is focused on designing the full-order observers that guarantee the global exponential stability of the error dynamic system. Based on the average dwell time approach and the free-weighting matrix technique, delay-dependent sufficient conditions are developed for the solvability of such problem and formulated as linear matrix inequalities. The error-state decay estimate is also given. Then, the stability analysis problem for the switched recurrent neural networks can be covered as a special case of our results. Finally, four illustrative examples are provided to demonstrate the effectiveness and the superiority of the proposed methods. © 2011 IEEE

  11. Defining and measuring the mean residence time of lateral surface transient storage zones in small streams

    Science.gov (United States)

    T.R. Jackson; R. Haggerty; S.V. Apte; A. Coleman; K.J. Drost

    2012-01-01

    Surface transient storage (STS) has functional significance in stream ecosystems because it increases solute interaction with sediments. After volume, mean residence time is the most important metric of STS, but it is unclear how this can be measured accurately or related to other timescales and field-measureable parameters. We studied mean residence time of lateral...

  12. Wake losses from averaged and time-resolved power measurements at full scale wind turbines

    Science.gov (United States)

    Castellani, Francesco; Astolfi, Davide; Mana, Matteo; Becchetti, Matteo; Segalini, Antonio

    2017-05-01

    This work deals with the experimental analysis of wake losses fluctuations at full-scale wind turbines. The test case is a wind farm sited on a moderately complex terrain: 4 turbines are installed, having 2 MW of rated power each. The sources of information are the time-resolved data, as collected from the OPC server, and the 10-minutes averaged SCADA data. The objective is to compare the statistical distributions of wake losses for far and middle wakes, as can be observed through the “fast” lens of time-resolved data, for certain selected test-case time series, and through the “slow” lens of SCADA data, on a much longer time basis that allow to set the standards of the mean wake losses along the wind farm. Further, time-resolved data are used for an insight into the spectral properties of wake fluctuations, highlighting the role of the wind turbine as low-pass filter. Summarizing, the wind rose, the layout of the site and the structure of the data sets at disposal allow to study middle and far wake behavior, with a “slow” and “fast” perspective.

  13. Time-varying cycle average and daily variation in ambient air pollution and fecundability.

    Science.gov (United States)

    Nobles, Carrie J; Schisterman, Enrique F; Ha, Sandie; Buck Louis, Germaine M; Sherman, Seth; Mendola, Pauline

    2018-01-01

    Does ambient air pollution affect fecundability? While cycle-average air pollution exposure was not associated with fecundability, we observed some associations for acute exposure around ovulation and implantation with fecundability. Ambient air pollution exposure has been associated with adverse pregnancy outcomes and decrements in semen quality. The LIFE study (2005-2009), a prospective time-to-pregnancy study, enrolled 501 couples who were followed for up to one year of attempting pregnancy. Average air pollutant exposure was assessed for the menstrual cycle before and during the proliferative phase of each observed cycle (n = 500 couples; n = 2360 cycles) and daily acute exposure was assessed for sensitive windows of each observed cycle (n = 440 couples; n = 1897 cycles). Discrete-time survival analysis modeled the association between fecundability and an interquartile range increase in each pollutant, adjusting for co-pollutants, site, age, race/ethnicity, parity, body mass index, smoking, income and education. Cycle-average air pollutant exposure was not associated with fecundability. In acute models, fecundability was diminished with exposure to ozone the day before ovulation and nitrogen oxides 8 days post ovulation (fecundability odds ratio [FOR] 0.83, 95% confidence interval [CI]: 0.72, 0.96 and FOR 0.84, 95% CI: 0.71, 0.99, respectively). However, particulate matter ≤10 microns 6 days post ovulation was associated with greater fecundability (FOR 1.25, 95% CI: 1.01, 1.54). Although our study was unlikely to be biased due to confounding, misclassification of air pollution exposure and the moderate study size may have limited our ability to detect an association between ambient air pollution and fecundability. While no associations were observed for cycle-average ambient air pollution exposure, consistent with past research in the United States, exposure during critical windows of hormonal variability was associated with prospectively measured couple

  14. Stable isotope fractionation in response to variable fluid residence time distributions

    Science.gov (United States)

    Druhan, J. L.; Maher, K.

    2013-12-01

    Hydrogeochemical processes governing groundwater quantity and quality are often inferred from fluid samples that are the flux-weighted average of a heterogeneous system. This connection has been demonstrated for solutes subject to transport and equilibrium constraints, in which the steady state concentration - discharge relationship is cast in terms of the choice of expression for residence time distribution (Maher, 2011). Here, we examine the extent to which the spatial correlation of the permeability field, which governs the fluid residence time distribution, exerts a principle control on the partitioning of stable isotopes between reactant and product species during heterogeneous reactions in groundwater systems. We demonstrate this relationship using numerical simulations of δ53Cr fractionation due to abiotic CrO42- reduction by Fe2+, implemented in the reactive transport code CrunchFlow. The chemically homogeneous redox reaction generates Cr3+ with an isotope ratio distinct from the reactant pool, and in turn this product species precipitates as a mineral phase Cr(OH)3(s) through a non-fractionating reaction. The corresponding chromate δ53Cr enrichment across a homogeneous domain varies from a maximum value set by the kinetic fractionation factor (αk) at high mean fluid residence times, to a value reaction-limited to transport-limited regimes. For physically heterogeneous flow fields, the transition in isotopic fractionation from a reaction-limited to a transport-limited regime becomes variable, and falls between the upper and lower bounds set by the homogeneous simulations at slow and fast precipitation rates, respectively. Our results show that while minimal variation occurs in the steady-state isotopic profile of the reactant species (δ53Cr of CrO42-), the combined effects of the precipitation rate and the heterogeneous structure of the porous media lead to a wide range in the steady state isotopic composition of the product species (δ53Cr of Cr3

  15. Residence times and nitrate transport in ground water discharging to streams in the Chesapeake Bay Watershed

    Science.gov (United States)

    Lindsey, Bruce D.; Phillips, Scott; Donnelly, Colleen A.; Speiran, Gary K.; Plummer, Niel; Bohlke, John Karl; Focazio, Michael J.; Burton, William C.; Busenberg, Eurybiades

    2003-01-01

    and Ridge siliciclastic HGMR and the Locust Grove Watershed in the Coastal Plain Uplands HGMR. A nutrient-reduction scenario was created for East Mahantango Creek, where the average residence time was determined to be approximately 10 years on the basis of the output of particle tracking from a ground-water-flow model. This scenario showed decreases of nearly 50 percent in base-flow concentrations of nitrate in streams within the first year after the reduction in nitrogen input; smaller reductions in nitrate concentration occurred in each subsequent year. A second scenario for that same watershed, in which the same 10-year average residence time was assumed and an exponential model was used for analysis, showed that a 50-percent reduction in base-flow concentrations of nitrate could take up to 5 years. For the Locust Grove Watershed, in which an average residence time of 32 years was assumed, simulation with the exponential model showed that it may take more than 20 years to achieve a 50-percent reduction in base-flow concentra-tions of nitrate. Although it was not possible to construct such scenarios for all watersheds, these examples show the range of possible responses to changes in nutrient inputs in two very different types of watersheds.Findings from this study include information on factors that affect ground-water age, spatial distribution of ages, and nitrogen transport. In the East Mahantango Creek Watershed and the Polecat Creek Watershed, the residence time varied spatially depending on the position of the flow path, and temporally depending on the recharge conditions. Generally, ground water in areas near the stream had short residence times and the water in upland areas had longer residence times. Water traveling through deep layers had longer residence times than water traveling through shallow layers, and residence times were faster under high recharge conditions than low recharge conditions. Ground water in the Pocomoke Watershed exhibits a

  16. Improve Gear Fault Diagnosis and Severity Indexes Determinations via Time Synchronous Average

    Directory of Open Access Journals (Sweden)

    Mohamed El Morsy

    2016-11-01

    Full Text Available In order to reduce operation and maintenance costs, prognostics and health management (PHM of the geared system is needed to improve effective gearbox fault detection tools.  PHM system allows less costly maintenance because it can inform operators of needed repairs before a fault causes collateral damage happens to the gearbox. In this article, time synchronous average (TSA technique and complex continuous wavelet analysis enhancement are used as gear fault detection approach. In the first step, extract the periodic waveform from the noisy measured signal is considered as The main value of Time synchronous averaging (TSA for gearbox signals analyses, where it allows the vibration signature of the gear under analysis to be separated from other gears and noise sources in the gearbox that are not synchronous with faulty gear. In the second step, the complex wavelet analysis is used in case of multi-faults in same gear. The signal phased-locked with the angular position of a shaft within the system is done. The main aims for this research is to improve the gear fault diagnosis and severity index determinations based on TSA  of measured signal for investigated passenger vehicle gearbox under different operation conditions. In addition to, correct the variations in shaft speed such that the spreading of spectral energy into an adjacent gear mesh bin helps in detecting the gear fault position (faulted tooth or teeth and improve the Root Mean Square (RMS, Kurtosis, and Peak Pulse as the sensitivity of severity indexes for maintenance, prognostics and health management (PHM purposes. The open loop test stand is equipped with two dynamometers and investigated vehicle gearbox of mid-size passenger car; the total power is taken-off from one side only. Reference Number: www.asrongo.org/doi:4.2016.1.1.6

  17. Accessing doctors at times of need-measuring the distance tolerance of rural residents for health-related travel.

    Science.gov (United States)

    McGrail, Matthew Richard; Humphreys, John Stirling; Ward, Bernadette

    2015-05-29

    Poor access to doctors at times of need remains a significant impediment to achieving good health for many rural residents. The two-step floating catchment area (2SFCA) method has emerged as a key tool for measuring healthcare access in rural areas. However, the choice of catchment size, a key component of the 2SFCA method, is problematic because little is known about the distance tolerance of rural residents for health-related travel. Our study sought new evidence to test the hypothesis that residents of sparsely settled rural areas are prepared to travel further than residents of closely settled rural areas when accessing primary health care at times of need. A questionnaire survey of residents in five small rural communities of Victoria and New South Wales in Australia was used. The two outcome measures were current travel time to visit their usual doctor and maximum time prepared to travel to visit a doctor, both for non-emergency care. Kaplan-Meier charts were used to compare the association between increased distance and decreased travel propensity for closely-settled and sparsely-settled areas, and ordinal multivariate regression models tested significance after controlling for health-related travel moderating factors and town clustering. A total of 1079 questionnaires were completed with 363 from residents in closely-settled locations and 716 from residents in sparsely-settled areas. Residents of sparsely-settled communities travel, on average, 10 min further than residents of closely-settled communities (26.3 vs 16.9 min, p time prepared to travel (54.1 vs 31.9 min, p time remained significant after controlling for demographic and other constraints to access, such as transport availability or difficulties getting doctor appointments, as well as after controlling for town clustering and current travel times. Improved geographical access remains a key issue underpinning health policies designed to improve the provision of rural primary health care

  18. The impact of dredging on residence time in the Amba estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Velamala, S.N.; Thomas, J.; Bari, S.; Kachave, S.

    increase from 1.2 to 1.3 tidal cycles after dredging. Keywords: Residence time. flushing time. modeling. lagrangian particle track. Amba estuary: India. 1. Introduction The rate of water exchange between an estuary and the open sea plays...; Monsen et al. 2002). For example, Delesalle and Sournia (1992) established a direct linear relationship between phytoplankton biomass in coral lagoons and the Residence time (RT). The rate of exchange is generally determined by 3 time scales, viz...

  19. Time-dependent density functional theory with twist-averaged boundary conditions

    Science.gov (United States)

    Schuetrumpf, B.; Nazarewicz, W.; Reinhard, P.-G.

    2016-05-01

    Background: Time-dependent density functional theory is widely used to describe excitations of many-fermion systems. In its many applications, three-dimensional (3D) coordinate-space representation is used, and infinite-domain calculations are limited to a finite volume represented by a spatial box. For finite quantum systems (atoms, molecules, nuclei, hadrons), the commonly used periodic or reflecting boundary conditions introduce spurious quantization of the continuum states and artificial reflections from boundary; hence, an incorrect treatment of evaporated particles. Purpose: The finite-volume artifacts for finite systems can be practically cured by invoking an absorbing potential in a certain boundary region sufficiently far from the described system. However, such absorption cannot be applied in the calculations of infinite matter (crystal electrons, quantum fluids, neutron star crust), which suffer from unphysical effects stemming from a finite computational box used. Here, twist-averaged boundary conditions (TABC) have been used successfully to diminish the finite-volume effects. In this work, we extend TABC to time-dependent modes. Method: We use the 3D time-dependent density functional framework with the Skyrme energy density functional. The practical calculations are carried out for small- and large-amplitude electric dipole and quadrupole oscillations of 16O. We apply and compare three kinds of boundary conditions: periodic, absorbing, and twist-averaged. Results: Calculations employing absorbing boundary conditions (ABC) and TABC are superior to those based on periodic boundary conditions. For low-energy excitations, TABC and ABC variants yield very similar results. With only four twist phases per spatial direction in TABC, one obtains an excellent reduction of spurious fluctuations. In the nonlinear regime, one has to deal with evaporated particles. In TABC, the floating nucleon gas remains in the box; the amount of nucleons in the gas is found to be

  20. Fluoroscopy time during uncomplicated unilateral ureteroscopy for urolithiasis decreases with urology resident experience.

    Science.gov (United States)

    Weld, Lancaster R; Nwoye, Uzoamaka O; Knight, Richard B; Baumgartner, Timothy S; Ebertowski, James S; Stringer, Matthew T; Kasprenski, Matthew C; Weld, Kyle J

    2015-01-01

    To determine predictors of fluoroscopy time during uncomplicated, unilateral ureteroscopy for urolithiasis performed by urology residents during the first 2 years of residency. The patient charts and computed tomography scans of consecutive, unilateral, uncomplicated ureteroscopy cases for urolithiasis were retrospectively reviewed. The cases were performed by beginning urology residents over the course of their first 2 years of urology residency training. A total of 200 ureteroscopy cases were reviewed. The mean stone diameter was 7.1 (±3.2) mm. Forty-three percent of cases were performed for renal stones and 58 % for ureteral stones. The mean operative time was 80.2 (±36.9) min. The mean fluoroscopy time was 69.1 (±38.2) s. No significant differences existed between cases performed by each of the two residents, and no statistical differences in case difficulty were observed throughout the study period. Linear regression analysis revealed the strongest association with lower fluoroscopy time to be increasing resident experience (p fluoroscopy time decreased by 79 % from 135 to 29 s per case. Other significant factors associated with increasing fluoroscopy time were placement of a postoperative stent under fluoroscopic guidance (p Fluoroscopy time during uncomplicated, unilateral ureteroscopy for urolithiasis decreases with increasing urology resident operative experience. Other technical options during ureteroscopy were also found to influence fluoroscopy time.

  1. One approach for minimising the average turnaround time in Varna West Port Terminal

    Directory of Open Access Journals (Sweden)

    Tanka Milkova

    2017-12-01

    Full Text Available One of the most important criteria for port efficiency nowadays is the average turnaround time. More and more port terminals are assessed by this indicator, so its value turns to be one of the crucial factors for ports competitiveness and consequently minimising the turnaround time becomes one of the most important objectives of the ports. The purpose of this research paper is to propose one interesting tool for optimising this indicator by using the famous Simplex method of linear programming. After giving the approach some exemplary models are solved with real values based on statistics for Varna West Port Terminal which will make the design of the paper original in both directions – theoretical and practical, so that despite some limitations concerning the trade secret, the scope of the material is large enough to be used for any port with any data, even exemplary and/or approximate. The aforementioned practical implications could be pointed out as the main contribution of this paper and the easy way for calculating the final results makes the algorithm really applicable so that each port can make its own conclusion based on its particular statistical data.

  2. Applicability of Time-Averaged Holography for Micro-Electro-Mechanical System Performing Non-Linear Oscillations

    Science.gov (United States)

    Palevicius, Paulius; Ragulskis, Minvydas; Palevicius, Arvydas; Ostasevicius, Vytautas

    2014-01-01

    Optical investigation of movable microsystem components using time-averaged holography is investigated in this paper. It is shown that even a harmonic excitation of a non-linear microsystem may result in an unpredictable chaotic motion. Analytical results between parameters of the chaotic oscillations and the formation of time-averaged fringes provide a deeper insight into computational and experimental interpretation of time-averaged MEMS holograms. PMID:24451467

  3. Applicability of Time-Averaged Holography for Micro-Electro-Mechanical System Performing Non-Linear Oscillations

    Directory of Open Access Journals (Sweden)

    Paulius Palevicius

    2014-01-01

    Full Text Available Optical investigation of movable microsystem components using time-averaged holography is investigated in this paper. It is shown that even a harmonic excitation of a non-linear microsystem may result in an unpredictable chaotic motion. Analytical results between parameters of the chaotic oscillations and the formation of time-averaged fringes provide a deeper insight into computational and experimental interpretation of time-averaged MEMS holograms.

  4. Applicability of time-averaged holography for micro-electro-mechanical system performing non-linear oscillations.

    Science.gov (United States)

    Palevicius, Paulius; Ragulskis, Minvydas; Palevicius, Arvydas; Ostasevicius, Vytautas

    2014-01-21

    Optical investigation of movable microsystem components using time-averaged holography is investigated in this paper. It is shown that even a harmonic excitation of a non-linear microsystem may result in an unpredictable chaotic motion. Analytical results between parameters of the chaotic oscillations and the formation of time-averaged fringes provide a deeper insight into computational and experimental interpretation of time-averaged MEMS holograms.

  5. Determination of the resident time distribution (RTD) in copper concentrate drying plants using radioactive tracers

    International Nuclear Information System (INIS)

    Diaz V, Francisco J.; Duran P, Oscar U.; Hernandez A, Fernando A.

    1996-01-01

    This paper is a study on the drying process of copper concentrate, on two fluidized bed dryers at Fundicion Caletones, Division El Teniente, Codelco-Chile. The problem was investigated by experimental determination of the resident Time Distribution (RTD) for the material to be dry and by an analysis of the influence of the grain size in the drying process. The stimulus-response technique was used in the experiments, where the stimulation was a pulse of an adequate radioactive tracer injected at the dryer's input. Under these conditions, the response obtained at the dryer's outputs, i.e., the concentration variation curve as a function of time, represents directly the RTD of the system between the injection and measuring points. The tracer used was the same material to be dried, and it was irradiated with neutrons in the nuclear reactor at La Reina Nuclear Centre, thus producing a solid gamma radiation emitter tracer of identical behaviour as the material under study. The approximate activity of each sample was equivalent to 8 mCi of Cu-64 at the time of the injection and the measurement of the tracer was made on-line using NaI(Tl) gamma radiation detectors. The results obtained showed average times less than the estimated and would indicate a fast drying using minimum volume in the dryer. The drying of the fine particles was three times faster than the coarse ones. (author)

  6. Effects of Surgical Assistant's Level of Resident Training on Surgical Treatment of Intermittent Exotropia: Operation Time and Surgical Outcomes.

    Science.gov (United States)

    Kim, Moo Hyun; Chung, Hyunuk; Kim, Won Jae; Kim, Myung Mi

    2018-02-01

    To evaluate the effects of the surgical assistant's level of resident training on operation time and surgical outcome in the surgical treatment of intermittent exotropia. This study included 456 patients with intermittent exotropia who underwent lateral rectus recession and medial rectus resection and were followed up for 24 months after surgery. The patients were divided into two groups according to the surgical assistant's level of resident training: group F (surgery assisted by a first-year resident [n = 198]) and group S (surgery assisted by a second-, third-, or fourth-year resident [n = 258]). The operation time and surgical outcomes (postoperative exodeviation and the number of patients who underwent a second operation) were compared between the two groups. The average operation times in groups F and S were 36.54 ± 7.4 and 37.34 ± 9.94 minutes, respectively (p = 0.33). Immediate postoperative exodeviation was higher in group F (0.79 ± 3.82 prism diopters) than in group S (0.38 ± 3.75 prism diopters). However, repeated-measures analysis of variance revealed no significant difference in exodeviation between the two groups during the 24-month follow-up period (p = 0.45). A second operation was performed in 29.3% (58 / 198) of the patients in group F, and in 32.2% (83 / 258) of those in group S (p = 0.51). No significant difference in operation time was observed when we compared the effects of the level of resident training in the surgical treatment of intermittent exotropia. Although the immediate postoperative exodeviation was higher in patients who had undergone surgery assisted by a first-year resident, the surgical outcome during the 24-month follow-up was not significantly different.

  7. Trait differences between naturalized and invasive plant species independent of residence time and phylogeny.

    Science.gov (United States)

    Gallagher, R V; Randall, R P; Leishman, M R

    2015-04-01

    The ability to predict which alien plants will transition from naturalized to invasive prior to their introduction to novel regions is a key goal for conservation and has the potential to increase the efficacy of weed risk assessment (WRA). However, multiple factors contribute to plant invasion success (e.g., functional traits, range characteristics, residence time, phylogeny), and they all must be taken into account simultaneously in order to identify meaningful correlates of invasion success. We compiled 146 pairs of phylogenetically paired (congeneric) naturalized and invasive plant species in Australia with similar minimum residence times (i.e., time since introduction in years). These pairs were used to test for differences in 5 functional traits (flowering duration, leaf size, maximum height, specific leaf area [SLA], seed mass) and 3 characteristics of species' native ranges (biome occupancy, mean annual temperature, and rainfall breadth) between naturalized and invasive species. Invasive species, on average, had larger SLA, longer flowering periods, and were taller than their congeneric naturalized relatives. Invaders also exhibited greater tolerance for different environmental conditions in the native range, where they occupied more biomes and a wider breadth of rainfall and temperature conditions than naturalized congeners. However, neither seed mass nor leaf size differed between pairs of naturalized and invasive species. A key finding was the role of SLA in distinguishing between naturalized and invasive pairs. Species with high SLA values were typically associated with faster growth rates, more rapid turnover of leaf material, and shorter lifespans than those species with low SLA. This suite of characteristics may contribute to the ability of a species to transition from naturalized to invasive across a wide range of environmental contexts and disturbance regimes. Our findings will help in the refinement of WRA protocols, and we advocate the inclusion

  8. Calculation of residence times and radiation doses using the standard PC software Excel

    International Nuclear Information System (INIS)

    Herzog, H.; Zilken, H.; Niederbremer, A.; Friedrich, W.; Mueller-Gaertner, H.W.

    1997-01-01

    We developed a program which aims to facilitate the calculation of radiation doses to single organs and the whole body. IMEDOSE uses Excel to include calculations, graphical displays, and interactions with the user in a single general-purpose PC software tool. To start the procedure the input data are copied into a spreadsheet. They must represent percentage uptake values of several organs derived from measurements in animals or humans. To extrapolate these data up to seven half-lives of the radionuclide, fitting to one or two exponentional functions is included and can be checked by the user. By means of the approximate time-activity information the cumulated activity or residence times are calculated. Finally these data are combined with the absorbed fraction doses (S-values) given by MIRD pamphlet No. 11 to yield radiation doses, the effective dose equivalent and the effective dose. These results are presented in a final table. Interactions are realized with push-buttons and drop-down menus. Calculations use the Visual Basic tool of Excel. In order to test our program, biodistribution data of fluorine-18 fluorodeoxyglucose were taken from the literature (Meija et al., J Nucl Med 1991; 32:699-706). For a 70-kg adult the resulting radiation doses of all target organs listed in MIRD 11 were different from the ICRP 53 values by 1%±18% on the average. When the residence times were introduced into MIRDOSE3 (Stabin, J Nucl Med 1996; 37:538-546) the mean difference between our results and those of MIRDOSE3 was -3%±6%. Both outcomes indicate the validity of the present approach. (orig.)

  9. Calculation of residence times and radiation doses using the standard PC software Excel.

    Science.gov (United States)

    Herzog, H; Zilken, H; Niederbremer, A; Friedrich, W; Müller-Gärtner, H W

    1997-12-01

    We developed a program which aims to facilitate the calculation of radiation doses to single organs and the whole body. IMEDOSE uses Excel to include calculations, graphical displays, and interactions with the user in a single general-purpose PC software tool. To start the procedure the input data are copied into a spreadsheet. They must represent percentage uptake values of several organs derived from measurements in animals or humans. To extrapolate these data up to seven half-lives of the radionuclide, fitting to one or two exponentional functions is included and can be checked by the user. By means of the approximate time-activity information the cumulated activity or residence times are calculated. Finally these data are combined with the absorbed fraction doses (S-values) given by MIRD pamphlet No. 11 to yield radiation doses, the effective dose equivalent and the effective dose. These results are presented in a final table. Interactions are realized with push-buttons and drop-down menus. Calculations use the Visual Basic tool of Excel. In order to test our program, biodistribution data of fluorine-18 fluorodeoxyglucose were taken from the literature (Meija et al., J Nucl Med 1991; 32:699-706). For a 70-kg adult the resulting radiation doses of all target organs listed in MIRD 11 were different from the ICRP 53 values by 1%+/-18% on the average. When the residence times were introduced into MIRDOSE3 (Stabin, J Nucl Med 1996; 37:538-546) the mean difference between our results and those of MIRDOSE3 was -3%+/-6%. Both outcomes indicate the validity of the present approach.

  10. Calculation of residence times and radiation doses using the standard PC software Excel

    Energy Technology Data Exchange (ETDEWEB)

    Herzog, H.; Zilken, H.; Niederbremer, A.; Friedrich, W. [Institute of Medicine, Research Center Juelich, Juelich (Germany); Mueller-Gaertner, H.W. [Institute of Medicine, Research Center Juelich, Juelich (Germany)]|[Department of Nuclear Medicine, Heinrich-Heine University Hospital Duesseldorf (Germany)

    1997-12-01

    We developed a program which aims to facilitate the calculation of radiation doses to single organs and the whole body. IMEDOSE uses Excel to include calculations, graphical displays, and interactions with the user in a single general-purpose PC software tool. To start the procedure the input data are copied into a spreadsheet. They must represent percentage uptake values of several organs derived from measurements in animals or humans. To extrapolate these data up to seven half-lives of the radionuclide, fitting to one or two exponentional functions is included and can be checked by the user. By means of the approximate time-activity information the cumulated activity or residence times are calculated. Finally these data are combined with the absorbed fraction doses (S-values) given by MIRD pamphlet No. 11 to yield radiation doses, the effective dose equivalent and the effective dose. These results are presented in a final table. Interactions are realized with push-buttons and drop-down menus. Calculations use the Visual Basic tool of Excel. In order to test our program, biodistribution data of fluorine-18 fluorodeoxyglucose were taken from the literature (Meija et al., J Nucl Med 1991; 32:699-706). For a 70-kg adult the resulting radiation doses of all target organs listed in MIRD 11 were different from the ICRP 53 values by 1%{+-}18% on the average. When the residence times were introduced into MIRDOSE3 (Stabin, J Nucl Med 1996; 37:538-546) the mean difference between our results and those of MIRDOSE3 was -3%{+-}6%. Both outcomes indicate the validity of the present approach. (orig.) With 5 figs., 2 tabs., 18 refs.

  11. Validity margins of Monin-Obukhov similarity theory for space and time averaged data

    Science.gov (United States)

    Ansorge, Cedrick

    2017-04-01

    Monin-Obukhov Similarity Theory (MOST) is the ubiquitous framework for the estimation of surface fluxes in atmospheric models. Motivated by tower-measurements, it is conceptually designed in an ensemble or time averaging context and does not take into account non-local effects. Hence, the limit of an infinite homogeneous surface is implicit in the assumptions underlying MOST. This limit is rarely encountered in the coupled land-atmosphere system which is characterized by broad scale heterogeneities in all quantities. Despite these known conceptual and practical deficiencies over heterogeneous surfaces, MOST or versions thereof, such as the MOSAIC approach, are routinely used over heterogeneous surfaces. In this talk, I present a systematic assessment of the scale margins and quantify the temporal and spatial limits of the validity of MOST by use of direct numerical simulation (DNS) of Ekman flow. This investigation of the scale limits of MOST over a homogeneous surface provides a physically-based temporal and spatial scale margin below which the interaction of the atmosphere and surface is to be modelled by physically different approaches. Further, the availability of a DNS dataset systematically investigating MOST allows an improved representation of interfacial fluxes.

  12. Development and application of a needle trap device for time-weighted average diffusive sampling.

    Science.gov (United States)

    Gong, Ying; Eom, In-Yong; Lou, Da-Wei; Hein, Dietmar; Pawliszyn, Janusz

    2008-10-01

    A simple, cost-effective analysis combining solventless extraction, thermal desorption, and determination of volatile organic compounds (VOCs) was developed and validated. A needle trap device (NTD) packed with the sorbent Carboxen1000 was used as a time-weighted average (TWA) diffusive sampler to collect target compounds by molecular diffusion and adsorption to the packed sorbent. This process can be described with derivations of Fick's first law of diffusion, which expresses the relation between the TWA concentrations to which the passive sampler is exposed and the mass of analytes adsorbed to the packed sorbent in the sampler. The effects of experimental factors such as temperature, pressure, humidity, and face velocity were taken into account in applying diffusive sampling under nonideal conditions. This study demonstrates that NTD is effective for air analysis of benzene, toluene, ethylbenzene, and o-xylene (BTEX), due to the good adsorption/desorption quality of Carboxen 1000 and to the special geometric shape of the needle with a small cross section avoiding the need for calibration. Storage tests showed good storage stability for BTEX. Verification of the theoretical model showed good agreement between theoretical and experimental sampling rates. Method validation done against NIOSH method 1501, SPME, and NTD active sampling revealed good agreement between those methods. Automated NTD sample introduction to a gas chromatograph facilitates the use of this technology for industrial hygiene applications.

  13. Effect of oven residence time on mechanical properties in ...

    Indian Academy of Sciences (India)

    P L Ramkumar

    Source based formu- lation was proposed by Banerjee et al [16] for modelling layer by layer non-isothermal deposition of plastic. The proposed method was also used for calculating the cycle time for ... alternative to reduce the cycle time in comparison with ... the energy inputs to the processes and save significant energy as ...

  14. Investigation of residence time and groundwater flux in Venice Lagoon: comparing radium isotope and hydrodynamic models.

    Science.gov (United States)

    Rapaglia, John; Ferrarin, Christian; Zaggia, Luca; Moore, Willard S; Umgiesser, Georg; Garcia-Solsona, Ester; Garcia-Orellana, Jordi; Masqué, Pere

    2010-07-01

    The four naturally-occurring isotopes of radium were coupled with a previously evaluated hydrodynamic model to determine the apparent age of surface waters and to quantify submarine groundwater discharge (SGD) into the Venice Lagoon, Italy. Mean apparent age of water in the Venice Lagoon was calculated using the ratio of 224Ra to 228Ra determined from 30 monitoring stations and a mean pore water end member. Average apparent age was calculated to be 6.0 d using Ra ratios. This calculated age was very similar to average residence time calculated for the same period using a hydrodynamic model (5.8 d). A mass balance of Ra was accomplished by quantifying each of the sources and sinks of Ra in the lagoon, with the unknown variable being attributed to SGD. Total SGD were calculated to be 4.1 +/- 1.5, 3.8 +/- 0.7, 3.0 +/- 1.3, and 3.5 +/- 1.0 x 10(10) L d(-1) for (223,224,226, 228)Ra, respectively, which are an order of magnitude larger than total mean fluvial discharge into the Venice Lagoon (3.1 x 10(9) L d(-1)). The SGD as a source of nutrients in the Venice Lagoon is also discussed and, though significant to the nutrient budget, is likely to be less important as the dominant control on SGD is recirculated seawater rather than freshwater. 2009 Elsevier Ltd. All rights reserved.

  15. XMM-Newton observation of the NLS1 galaxy Ark 564. I. Spectral analysis of the time-average spectrum

    NARCIS (Netherlands)

    Papadakis, I.E.; Brinkmann, W.; Page, M.J.; McHardy, I.; Uttley, P.

    2007-01-01

    Context: .We present the results from the spectral analysis of the time-average spectrum of the Narrow Line Seyfert 1 (NLS1) galaxy Ark 564 from a ~100 ks XMM-Newton observation. Aims: .Our aim is to characterize accurately the shape of the time-average, X-ray continuum spectrum of the source and

  16. MODELING HOW A HURRICANE BARRIER IN NEW BEDFORD HARBOR, MASSACHUSETTS, AFFECTS THE HYDRODYNAMICS AND RESIDENCE TIMES

    Science.gov (United States)

    Two-dimensional hydrodynamic and transport models were used to simulate tidal and subtidal circulation, residence times, and the longitudinal distributions of conservative constituents in New Bedford Harbor, Massachusetts, before and after a hurricane barrier was constructed. The...

  17. Evaluation of Residence Time on Nitrogen Oxides Removal in Non-Thermal Plasma Reactor

    Science.gov (United States)

    Talebizadeh, Pouyan; Rahimzadeh, Hassan; Babaie, Meisam; Javadi Anaghizi, Saeed; Ghomi, Hamidreza; Ahmadi, Goodarz; Brown, Richard

    2015-01-01

    Non-thermal plasma (NTP) has been introduced over the last few years as a promising after- treatment system for nitrogen oxides and particulate matter removal from diesel exhaust. NTP technology has not been commercialised as yet, due to its high rate of energy consumption. Therefore, it is important to seek out new methods to improve NTP performance. Residence time is a crucial parameter in engine exhaust emissions treatment. In this paper, different electrode shapes are analysed and the corresponding residence time and NOx removal efficiency are studied. An axisymmetric laminar model is used for obtaining residence time distribution numerically using FLUENT software. If the mean residence time in a NTP plasma reactor increases, there will be a corresponding increase in the reaction time and consequently the pollutant removal efficiency increases. Three different screw thread electrodes and a rod electrode are examined. The results show the advantage of screw thread electrodes in comparison with the rod electrode. Furthermore, between the screw thread electrodes, the electrode with the thread width of 1 mm has the highest NOx removal due to higher residence time and a greater number of micro-discharges. The results show that the residence time of the screw thread electrode with a thread width of 1 mm is 21% more than for the rod electrode. PMID:26496630

  18. Evaluation of Residence Time on Nitrogen Oxides Removal in Non-Thermal Plasma Reactor.

    Directory of Open Access Journals (Sweden)

    Pouyan Talebizadeh

    Full Text Available Non-thermal plasma (NTP has been introduced over the last few years as a promising after- treatment system for nitrogen oxides and particulate matter removal from diesel exhaust. NTP technology has not been commercialised as yet, due to its high rate of energy consumption. Therefore, it is important to seek out new methods to improve NTP performance. Residence time is a crucial parameter in engine exhaust emissions treatment. In this paper, different electrode shapes are analysed and the corresponding residence time and NOx removal efficiency are studied. An axisymmetric laminar model is used for obtaining residence time distribution numerically using FLUENT software. If the mean residence time in a NTP plasma reactor increases, there will be a corresponding increase in the reaction time and consequently the pollutant removal efficiency increases. Three different screw thread electrodes and a rod electrode are examined. The results show the advantage of screw thread electrodes in comparison with the rod electrode. Furthermore, between the screw thread electrodes, the electrode with the thread width of 1 mm has the highest NOx removal due to higher residence time and a greater number of micro-discharges. The results show that the residence time of the screw thread electrode with a thread width of 1 mm is 21% more than for the rod electrode.

  19. Evaluation of Residence Time on Nitrogen Oxides Removal in Non-Thermal Plasma Reactor.

    Science.gov (United States)

    Talebizadeh, Pouyan; Rahimzadeh, Hassan; Babaie, Meisam; Javadi Anaghizi, Saeed; Ghomi, Hamidreza; Ahmadi, Goodarz; Brown, Richard

    2015-01-01

    Non-thermal plasma (NTP) has been introduced over the last few years as a promising after- treatment system for nitrogen oxides and particulate matter removal from diesel exhaust. NTP technology has not been commercialised as yet, due to its high rate of energy consumption. Therefore, it is important to seek out new methods to improve NTP performance. Residence time is a crucial parameter in engine exhaust emissions treatment. In this paper, different electrode shapes are analysed and the corresponding residence time and NOx removal efficiency are studied. An axisymmetric laminar model is used for obtaining residence time distribution numerically using FLUENT software. If the mean residence time in a NTP plasma reactor increases, there will be a corresponding increase in the reaction time and consequently the pollutant removal efficiency increases. Three different screw thread electrodes and a rod electrode are examined. The results show the advantage of screw thread electrodes in comparison with the rod electrode. Furthermore, between the screw thread electrodes, the electrode with the thread width of 1 mm has the highest NOx removal due to higher residence time and a greater number of micro-discharges. The results show that the residence time of the screw thread electrode with a thread width of 1 mm is 21% more than for the rod electrode.

  20. The distribution of range sizes of native and alien plants in four European countries and the effects of residence time

    OpenAIRE

    Williamson, Mark; Dehnen-Schmutz, Katharina; Kühn, Ingolf; Hill, Mark; Klotz, Stefan; Milbau , Ann; Stout, Jane; Pyšek, Petr

    2009-01-01

    Aim Do the statistical distributions of range sizes of native and alien species differ? If so, is this because of residence time effects? And can such effects indicate an average time to a maximum?\\ud \\ud Location Ireland, Britain, Germany and the Czech Republic.\\ud \\ud Methods The data are presence or absence of higher plants in mapping units of 100 km2 (Ireland and Britain) or c. 130 km2 (Germany and the Czech Republic) in areas varying from 79 to 357 thousand km2. Logit transforms of range...

  1. Climate Variable is Time-Averaged: Dealing with Uncertainty of Paleoclimatic Record Caused by Smoothening of Noisy Variations

    Science.gov (United States)

    Umemura, K.; Ebina, K.

    2014-12-01

    Climate is the average of weather over some time period and shows characteristic behavior in each time scale. In paleoclimatic research, values of climate variables are measured from proxies that give time series of time-averaged variables. Therefore, understanding the dynamics of time-averaged variable is important to investigate climate variations thorough different time scales. In our recent study, we formulated how stochastic dynamics changes corresponding to averaging time intervals using one dimensional first order stochastic differential equation which contains parametrically controlled terms of deterministic single-well or double-well potential force and random force. The dynamics of time-averaged variable is described by conditional probability density function. In the case of single-well, the function is analytically derived as normal distribution with scaling parameters. In the case of double-well potential, the function is obtained as skew generalized normal distribution function through numerical simulations. The mathematical framework of stochastic dynamics of time-averaged variable is general and applicable to analysis of many kinds of climate time series data. In this study, we apply the above framework to the analysis of proxy data from ice core and discuss about time scaling of the past climate variations. We test several models to infer the optimal model description for the data.

  2. The imprint of climate and geology on the residence times of groundwater

    Science.gov (United States)

    Maxwell, Reed M.; Condon, Laura E.; Kollet, Stefan J.; Maher, Kate; Haggerty, Roy; Forrester, Mary Michael

    2016-01-01

    Surface and subsurface flow dynamics govern residence time or water age until discharge, which is a key metric of storage and water availability for human use and ecosystem function. Although observations in small catchments have shown a fractal distribution of ages, residence times are difficult to directly quantify or measure in large basins. Here we use a simulation of major watersheds across North America to compute distributions of residence times. This simulation results in peak ages from 1.5 to 10.5 years, in agreement with isotopic observations from bomb-derived radioisotopes, and a wide range of residence times—from 0.1 to 10,000 years. This simulation suggests that peak residence times are controlled by the mean hydraulic conductivity, a function of the prevailing geology. The shape of the residence time distribution is dependent on aridity, which in turn determines water table depth and the frequency of shorter flow paths. These model results underscore the need for additional studies to characterize water ages in larger systems.

  3. Prevalence and cost of full-time research fellowships during general surgery residency: a national survey.

    Science.gov (United States)

    Robertson, Charles M; Klingensmith, Mary E; Coopersmith, Craig M

    2009-01-01

    To quantify the prevalence, outcomes, and cost of surgical resident research. General surgery is unique among graduate medical education programs because a large percentage of residents interrupt their clinical training to spend 1 to 3 years performing full-time research. No comprehensive data exists on the scope of this practice. Survey sent to all 239 program directors of general surgery residencies participating in the National Resident Matching Program. Response rate was 200 of 239 (84%). A total of 381 of 1052 trainees (36%) interrupt residency to pursue full-time research. The mean research fellowship length is 1.7 years, with 72% of trainees performing basic science research. A significant association was found between fellowship length and postresidency activity, with a 14.7% increase in clinical fellowship training and a 15.2% decrease in private practice positions for each year of full-time research (P < 0.0001). Program directors at 31% of programs reported increased clinical duties for research fellows as a result of Accreditation Council for Graduate Medical Education work hour regulations for clinical residents, whereas a further 10% of programs are currently considering such changes. It costs $41.5 million to pay the 634 trainees who perform research fellowships each year, the majority of which is paid for by departmental funds (40%) and institutional training grants (24%). Interrupting residency to perform a research fellowship is a common and costly practice among general surgery residents. Although performing a research fellowship is associated with clinical fellowship training after residency, it is unclear to what extent this practice leads to the development of surgical investigators after postgraduate training.

  4. Effect of Residence Time of Graphitisation on Thermal Conductivity of Molded Graphite

    Directory of Open Access Journals (Sweden)

    Pedy Artsanti

    2010-06-01

    Full Text Available The effect of residence time of graphitisation on thermal conductivity of molded graphite has been examined. The examination has been conducted by varying residence time of graphitisation of molded carbon with petroleum coke as raw material and coal tar pitch. Graphitisation has been conducted by heating molded graphite at 2500 °C in argon atmosphere with residention time of 10, 30 and 90 minutes. Graphitisation degree, density, shrinking mass and porosity of molded graphite were examined and so was its thermal conductivity. The result showed that the decrease of porosity and the increase of graphitisation degree due to the increasing of residention time of graphitisation will increase the thermal conductivity of graphite. Molded graphite graphitisized with residence time for 90 minutes residention time gave thermal conductivity of 2.134 Watt/mK and graphitization degree 0.718.

  5. Short-term sandbar variability based on video imagery: Comparison between Time-Average and Time-Variance techniques

    Science.gov (United States)

    Guedes, R.M.C.; Calliari, L.J.; Holland, K.T.; Plant, N.G.; Pereira, P.S.; Alves, F.N.A.

    2011-01-01

    Time-exposure intensity (averaged) images are commonly used to locate the nearshore sandbar position (xb), based on the cross-shore locations of maximum pixel intensity (xi) of the bright bands in the images. It is not known, however, how the breaking patterns seen in Variance images (i.e. those created through standard deviation of pixel intensity over time) are related to the sandbar locations. We investigated the suitability of both Time-exposure and Variance images for sandbar detection within a multiple bar system on the southern coast of Brazil, and verified the relation between wave breaking patterns, observed as bands of high intensity in these images and cross-shore profiles of modeled wave energy dissipation (xD). Not only is Time-exposure maximum pixel intensity location (xi-Ti) well related to xb, but also to the maximum pixel intensity location of Variance images (xi-Va), although the latter was typically located 15m offshore of the former. In addition, xi-Va was observed to be better associated with xD even though xi-Ti is commonly assumed as maximum wave energy dissipation. Significant wave height (Hs) and water level (??) were observed to affect the two types of images in a similar way, with an increase in both Hs and ?? resulting in xi shifting offshore. This ??-induced xi variability has an opposite behavior to what is described in the literature, and is likely an indirect effect of higher waves breaking farther offshore during periods of storm surges. Multiple regression models performed on xi, Hs and ?? allowed the reduction of the residual errors between xb and xi, yielding accurate estimates with most residuals less than 10m. Additionally, it was found that the sandbar position was best estimated using xi-Ti (xi-Va) when xb was located shoreward (seaward) of its mean position, for both the first and the second bar. Although it is unknown whether this is an indirect hydrodynamic effect or is indeed related to the morphology, we found that this

  6. Residence time of pollutants discharged in the Gulf of Kachchh, northwestern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Patgaonkar, R.S.; Vethamony, P.; Lokesh, K.S.; Babu, M.T.

    − = 0 The residence time is defined as the time when the mass declines to 1/e of its initial value m 0 , i.e. τ== k t 1 This theory assumes steady state flow. It also assumes complete and instantaneous mixing and that mass leaving the system... of the time of release (spring vs neap tide), the location of release and the initial vertical placement (Warner et al, 2010). Generally during neap tides, residence time is maximum near the bottom of the estuary at the mid-salt intrusion length. During...

  7. Time-averaging within the excited state of the nitrogen-vacancy centre in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, L J; McMurtrie, R L; Sellars, M J; Manson, N B [Laser Physics Center, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia)], E-mail: lachlan.rogers@anu.edu.au

    2009-06-15

    The emission intensity of diamond samples containing negatively charged nitrogen-vacancy centres are measured as a function of magnetic field along the (111) direction for various temperatures. At low temperatures the responses are sample and stress dependent and can be modelled in terms of the previous understanding of the {sup 3}E excited state fine structure which is strain dependent. At room temperature the responses are largely sample and stress independent, and modelling involves invoking a strain independent excited state with a single zero field spin-level splitting of 1.42 GHz. The change in behaviour is attributed to a temperature dependent averaging process over the components of the excited state orbital doublet. It decouples orbit and spin and at high temperature the spin levels become independent of any orbit splitting. One significant implication of this averaging is that it simplifies the development of room temperature applications.

  8. Time-averaging within the excited state of the nitrogen-vacancy centre in diamond

    Science.gov (United States)

    Rogers, L. J.; McMurtrie, R. L.; Sellars, M. J.; Manson, N. B.

    2009-06-01

    The emission intensity of diamond samples containing negatively charged nitrogen-vacancy centres are measured as a function of magnetic field along the lang111rang direction for various temperatures. At low temperatures the responses are sample and stress dependent and can be modelled in terms of the previous understanding of the 3E excited state fine structure which is strain dependent. At room temperature the responses are largely sample and stress independent, and modelling involves invoking a strain independent excited state with a single zero field spin-level splitting of 1.42 GHz. The change in behaviour is attributed to a temperature dependent averaging process over the components of the excited state orbital doublet. It decouples orbit and spin and at high temperature the spin levels become independent of any orbit splitting. One significant implication of this averaging is that it simplifies the development of room temperature applications.

  9. Area-averaged surface fluxes and their time-space variability over the FIFE experimental domain

    Science.gov (United States)

    Smith, E. A.; Hsu, A. Y.; Crosson, W. L.; Field, R. T.; Fritschen, L. J.; Gurney, R. J.; Kanemasu, E. T.; Kustas, W. P.; Nie, D.; Shuttleworth, W. J.

    1992-01-01

    The underlying mean and variance properties of surface net radiation, sensible-latent heat fluxes and soil heat flux are studied over the densely instrumented grassland region encompassing FIFE. Flux variability is discussed together with the problem of scaling up to area-averaged fluxes. Results are compared and contrasted for cloudy and clear situations and examined for the influence of surface-induced biophysical controls (burn and grazing treatments) and topographic controls (aspect ratios and slope factors).

  10. Design strategies to address kinetics of drug binding and residence time.

    Science.gov (United States)

    Cusack, Kevin P; Wang, Ying; Hoemann, Michael Z; Marjanovic, Jasmina; Heym, Roland G; Vasudevan, Anil

    2015-01-01

    The kinetics of drug binding and drug residence time are recognized to be important in the clinical effectiveness of drug candidates. In most cases a long residence time of the drug-target complex results in an extended duration of pharmacodynamic activity, even when systemic concentrations of drug have been notably reduced through elimination routes. Hence, if selective for target, long residence times can increase the duration of drug efficacy in vivo and can significantly diminish the potential for off-target-mediated toxicities. Furthermore, a compound with a slower dissociation rate may allow a reduced dosing schedule relative to a compound with a rapid dissociation rate. Factors contributing to long residence time that could be useful to medicinal chemists in the prospective design of compounds with long residence times will be discussed in this perspective. Particular emphasis will be on case studies highlighting how kinetics can be measured, modulated based on supporting structure kinetic relationships and whether these effects are translatable into man. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Scrutinizing the carbon cycle and CO2 residence time in the atmosphere

    Science.gov (United States)

    Harde, Hermann

    2017-05-01

    Climate scientists presume that the carbon cycle has come out of balance due to the increasing anthropogenic emissions from fossil fuel combustion and land use change. This is made responsible for the rapidly increasing atmospheric CO2 concentrations over recent years, and it is estimated that the removal of the additional emissions from the atmosphere will take a few hundred thousand years. Since this goes along with an increasing greenhouse effect and a further global warming, a better understanding of the carbon cycle is of great importance for all future climate change predictions. We have critically scrutinized this cycle and present an alternative concept, for which the uptake of CO2 by natural sinks scales proportional with the CO2 concentration. In addition, we consider temperature dependent natural emission and absorption rates, by which the paleoclimatic CO2 variations and the actual CO2 growth rate can well be explained. The anthropogenic contribution to the actual CO2 concentration is found to be 4.3%, its fraction to the CO2 increase over the Industrial Era is 15% and the average residence time 4 years.

  12. Residence half-time of {sup 137}Cs in the top-soils of Japanese paddy and upland fields

    Energy Technology Data Exchange (ETDEWEB)

    Komamura, Misako [National Inst. of Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan); Tsumura, Akito; Kodaira, Kiyoshi

    1999-03-01

    A series of top-soil samples of 14 paddy fields and 10 upland fields in Japan, were annually collected during more than 30 years, to be examined in the contents of {sup 137}Cs. The data, which were obtained by the use of a gamma spectrometric system, received some statistical treatments to distinguish the annual decline of {sup 137}Cs contents from deviations. Then the authors calculated `residence half-time of {sup 137}Cs` within top-soil, and `eluviation rate of {sup 137}Cs` from top to the sub-layer of the soil. The following nationwide results were obtained irrespective of paddy or upland field: (1) The `apparent residence half-time` was estimated as 16 - 17 years. This consists of both effects of eluviation and nuclear disintegration. (2) The true residence half-time` was reported as 41 - 42 years. This depends on the eluviation speed of {sup 137}Cs exclusively, because the influence of nuclear disintegration has been compensated. (3) The eluviation rate of {sup 137}Cs from top-soil down to the sub-soil was 1.6 - 1.7% per year. (4) The ratio of distribution of {sup 137}Cs between top-soil and the sub-soil was estimated to be 6:4 as average at the date of 1996. (author)

  13. Time series forecasting using ERNN and QR based on Bayesian model averaging

    Science.gov (United States)

    Pwasong, Augustine; Sathasivam, Saratha

    2017-08-01

    The Bayesian model averaging technique is a multi-model combination technique. The technique was employed to amalgamate the Elman recurrent neural network (ERNN) technique with the quadratic regression (QR) technique. The amalgamation produced a hybrid technique known as the hybrid ERNN-QR technique. The potentials of forecasting with the hybrid technique are compared with the forecasting capabilities of individual techniques of ERNN and QR. The outcome revealed that the hybrid technique is superior to the individual techniques in the mean square error sense.

  14. A Systematic Comparison of Particle Filter and EnKF in Assimilating Time-Averaged Observations

    Science.gov (United States)

    Liu, Huaran; Liu, Zhengyu; Lu, Feiyu

    2017-12-01

    The particle filter (PF) and the ensemble Kalman filter (EnKF) are two promising and popularly adopted types of ensemble-based data assimilation methods for paleoclimate reconstruction. However, no systematic comparison between them has been attempted. We compare these two uncertainty based methods in pseudoproxy experiments where synthetic seasonal mean sea surface temperature observations are assimilated. Their skills are evaluated with regards to local, hemispherically averaged and globally averaged analysis error, and their ability to capture large-scale modes of variability. It is found that the EAKF (Ensemble Adjustment Kalman filter, a variant of EnKF) performs better than the PF with only one third of the ensemble size, despite PF's theoretical superiority in allowing for non-Gaussian statistics and nonlinear dynamics. The success of the EAKF is attributed to the facts that (1) Gaussian assumption is somewhat appropriate for this application; (2) The EAKF is less sensitive to sampling errors than the PF due to the different methodological natures. Sixteen members are enough to estimate accurate covariance for the EAKF, but 48 (even 96) members still underrepresent the state space of high-dimensional system for the PF. Our study highlights the importance of a large localization radius in the application of the EnKF to paleoclimate reconstruction due to the sparse proxy network and suggests that additional techniques, such as localization or clustered particle filter, are needed to improve the PF for paleoclimate reconstruction, in addition to the simple importance resampling currently adopted by most research.

  15. Residence times and decay rates of downed woody debris biomass/carbon in eastern US forests

    Science.gov (United States)

    Matthew B. Russell; Christopher W. Woodall; Shawn Fraver; Anthony W. D' Amato; Grant M. Domke; Kenneth E. Skog

    2014-01-01

    A key component in describing forest carbon (C) dynamics is the change in downed dead wood biomass through time. Specifically, there is a dearth of information regarding the residence time of downed woody debris (DWD), which may be reflected in the diversity of wood (for example, species, size, and stage of decay) and site attributes (for example, climate) across the...

  16. Strategic Application of Residence-Time Control in Continuous-Flow Reactors

    Science.gov (United States)

    Mándity, István M; Ötvös, Sándor B; Fülöp, Ferenc

    2015-01-01

    As a sustainable alternative for conventional batch-based synthetic techniques, the concept of continuous-flow processing has emerged in the synthesis of fine chemicals. Systematic tuning of the residence time, a key parameter of continuous-reaction technology, can govern the outcome of a chemical reaction by determining the reaction rate and the conversion and by influencing the product selectivity. This review furnishes a brief insight into flow reactions in which high chemo- and/or stereoselectivity can be attained by strategic residence-time control and illustrates the importance of the residence time as a crucial parameter in sustainable method development. Such a fine reaction control cannot be performed in conventional batch reaction set-ups. PMID:26246983

  17. Computation of residence time in the simulation of pulsatile ventricular assist devices

    Science.gov (United States)

    Long, C. C.; Esmaily-Moghadam, M.; Marsden, A. L.; Bazilevs, Y.

    2014-10-01

    A continuum-based model of particle residence time for moving-domain fluid mechanics and fluid-structure interaction (FSI) computations is proposed, analyzed, and applied to the simulation of an adult pulsatile ventricular assist device (PVAD). Residence time is a quantity of clinical interest for blood pumps because it correlates with thrombotic risk. The proposed technique may be easily implemented in any flow or FSI solver. In the context of PVADs the results of the model may be used to assess how efficiently the pump moves the blood through its interior. Three scalar measures of particle residence time are also proposed. These scalar quantities may be used in the PVAD design with the goal of reducing thrombotic risk.

  18. High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: influence of contaminated fish consumption

    Energy Technology Data Exchange (ETDEWEB)

    Lee Ching-Chang; Lin Wu-Ting; Liao Po-Chi; Su Huey-Jen [Dept. of Environmental and Occupational Health/Research Center of Environmental Trace Toxic substances, Medical Coll., National Cheng Kung Univ., Tainan (Taiwan); Chen Hsiu-Lin [Inst. of Basic Medical Sciences, Medical Coll., National Cheng Kung Univ., Tainan (Taiwan)

    2004-09-15

    Many reports have suggested that PCDD/Fs (polychlorinated dibenzo-p-dioxins and dibenzofurans) contribute to immune deficiency, liver damage, human carcinogenesis, and neuromotor maturation in children. Therefore, beginning in 1999, the Taiwan Environmental Protection Agency (EPA) conducted a survey to determine serum levels of PCDD/Fs in the general populations living around 19 incinerators in Taiwan. Relatively high average serum PCDD/F levels were unexpectedly found in Tainan city, a less industrialized area in southwestern Taiwan, than in other urban areas. We therefore reviewed the usage history of the land and found that a factory situated between Hsien-Gong Li and Lu-Erh Li, two administrative units of Tainan city, had been manufacturing pentachlorophenol (PCP) between 1967 and 1982. PCDD/Fs are formed as byproducts in the PCP manufacturing process. Exposure to PCP and its derivatives via the food chain is the most significant intake route of PCDD/Fs in consumers in the European Union (EU). In Japan, in addition to combustion processes, PCP and chlornitrofen (CNP) have also been identified as the major sources of PCDD/Fs in Tokyo Bay7. A preliminary investigation showed that the soil in the PCP factory and sediments in the sea reservoir (13 hectares) near the deserted factory were seriously contaminated with PCDD/Fs (260-184,000 and 20-6220 pg I-TEQ/g, respectively), levels higher than those in other countries. Therefore, the aim of this study was to compare the PCDD/F levels of fish meat in the sea reservoir and the serum in inhabitants living in the vicinity of the closed PCP plant and other nearby areas. The data from human and other biota samples might clarify the transmission pathway of the PCDD/F contaminants from the PCP factory to local residents, provide information about the exposure status of those living in the vicinity of the deserted PCP factory, and also lead to useful suggestions for controlling PCDD/F accumulation in those living near such

  19. On the joint residence time of N independent two-dimensional Brownian motions

    International Nuclear Information System (INIS)

    Benichou, O; Coppey, M; Klafter, J; Moreau, M; Oshanin, G

    2003-01-01

    We study the behaviour of several joint residence times of N independent Brownian particles in a disc of radius R in two dimensions. We consider: (i) the time T N (t) spent by all N particles simultaneously in the disc within the time interval [0, t], (ii) the time T (m) N (t) which at least m out of N particles spend together in the disc within the time interval [0, t], and (iii) the time T-tilde (m) N (t) which exactly m out of N particles spend together in the disc within the time interval [0, t]. We obtain very simple exact expressions for the expectations of these three residence times in the limit t → ∞

  20. Regional oxygen reduction and denitrification rates in groundwater from multi-model residence time distributions, San Joaquin Valley, USA

    Science.gov (United States)

    Green, Christopher T.; Jurgens, Bryant; Zhang, Yong; Starn, Jeffrey; Singleton, Michael J.; Esser, Bradley K.

    2016-01-01

    Rates of oxygen and nitrate reduction are key factors in determining the chemical evolution of groundwater. Little is known about how these rates vary and covary in regional groundwater settings, as few studies have focused on regional datasets with multiple tracers and methods of analysis that account for effects of mixed residence times on apparent reaction rates. This study provides insight into the characteristics of residence times and rates of O2 reduction and denitrification (NO3− reduction) by comparing reaction rates using multi-model analytical residence time distributions (RTDs) applied to a data set of atmospheric tracers of groundwater age and geochemical data from 141 well samples in the Central Eastern San Joaquin Valley, CA. The RTD approach accounts for mixtures of residence times in a single sample to provide estimates of in-situ rates. Tracers included SF6, CFCs, 3H, He from 3H (tritiogenic He),14C, and terrigenic He. Parameter estimation and multi-model averaging were used to establish RTDs with lower error variances than those produced by individual RTD models. The set of multi-model RTDs was used in combination with NO3− and dissolved gas data to estimate zero order and first order rates of O2 reduction and denitrification. Results indicated that O2 reduction and denitrification rates followed approximately log-normal distributions. Rates of O2 and NO3− reduction were correlated and, on an electron milliequivalent basis, denitrification rates tended to exceed O2 reduction rates. Estimated historical NO3− trends were similar to historical measurements. Results show that the multi-model approach can improve estimation of age distributions, and that relatively easily measured O2 rates can provide information about trends in denitrification rates, which are more difficult to estimate.

  1. Implication of discharge pattern of radionuclides in the landscape on surface hydrological pathways and residence times

    International Nuclear Information System (INIS)

    Anders Woerman; Lars Marklund; Xu Shulan; Bjoern Dverstorp

    2005-01-01

    The safety analysis of the final repository of spent nuclear fuel will include large-scale migration behaviour of radionuclides that accidentally leak from the repository in deep bedrock. Physically based models of radionuclides release-processes would typically take into account the flow and transport in the hydrosphere as well as spreading through ecosystems to individual humans. This study addresses the coupling between discharge pattern in the landscape and factors controlling the residence times or radionuclides in the biosphere on land. The overall residence time on land is crucial because it controls the maximum exposure of radioactivity to individual humans. Numerical analysis indicate that variation in topography and quaternary deposits affect the discharge pattern in the landscape for radionuclides that escapes the waste repository in deep bedrock. Those analyses are based on extensive geographical data covering surface topography, stream network characteristics and geological structure on the continental scale of Scandinavia. Results on the discharge pattern in three typical Swedish landscapes are used as a basis for comparative analyses of the residence time distribution in surface hydrological systems for radionuclides that escape the waste repository. The groundwater flow analyses show that pathways of deep groundwater predominantly lead to the stream network, but to some extent also to lakes, wetlands and root uptake. The proportion varies slightly with altitude in the watershed as well as between different watersheds. The residence times in the stream network was based on convoluting the residence times for single discharge points over the entire stream network according to the technique of and data on stream distance distribution. The retardation due to uptake in the hyporheic zone was accounted for using the methods of and estimated sorption properties for Cs-137. The residence time for radionuclides in the hydrological systems of the continent

  2. Educating pediatric residents about breastfeeding: evaluation of 3 time-efficient teaching strategies.

    Science.gov (United States)

    Tender, Jennifer A F; Cuzzi, Sandra; Kind, Terry; Simmens, Samuel J; Blatt, Benjamin; Greenberg, Larrie

    2014-11-01

    Previously reported breastfeeding curricula for residents have combined different teaching methods, have focused on knowledge and attitudes, and have been time-intensive. This study aimed to evaluate 3 time-efficient breastfeeding curricula for effectiveness in regard to pediatric residents' knowledge, confidence, and skills in managing a simulated breastfeeding scenario. First-year pediatric residents during their 4-week community hospital newborn nursery rotation were consecutively assigned to 1 of 3 groups. Group 1 shadowed an International Board Certified Lactation Consultant (IBCLC) for 1 hour; group 2 watched a 25-minute case-based breastfeeding DVD; and group 3 observed a 3-hour prenatal parent breastfeeding class (CLS). Residents were assessed by (1) a pretest and posttest evaluating their breastfeeding knowledge and confidence, and (2) a clinical skills scenario managing a breastfeeding standardized patient (SP). Thirty-nine pediatric residents participated in the study (11 in IBCLC, 16 DVD, 12 CLS) over a 1-year period. All groups significantly improved their knowledge scores and confidence in managing breastfeeding problems, with the IBCLC group showing more improvement in knowledge than the other groups (P = .02) and a higher rating of their teaching method (P = .01). All groups performed well on the SP clinical skills scenario, with no significant difference between groups. All 3 teaching methods were time-efficient and produced important gains in knowledge and confidence, with residents in the IBCLC group demonstrating greatest improvement in knowledge and a higher rating of their teaching method. Our study provides support for 3 methods of teaching residents breastfeeding management and demonstrates that IBCLCs are well-received as interprofessional educators. © The Author(s) 2014.

  3. Conceptual framework for model-based analysis of residence time distribution in twin-screw granulation

    DEFF Research Database (Denmark)

    Kumar, Ashish; Vercruysse, Jurgen; Vanhoorne, Valerie

    2015-01-01

    within each module where different granulation rate processes dominate over others. Currently, experimental data is used to determine the residence time distributions. In this study, a conceptual model based on classical chemical engineering methods is proposed to better understand and simulate...... the residence time distribution in a TSG. The experimental data were compared with the proposed most suitable conceptual model to estimate the parameters of the model and to analyse and predict the effects of changes in number of kneading discs and their stagger angle, screw speed and powder feed rate...

  4. Inferring detailed space use from movement paths: A unifying, residence time-based framework.

    Science.gov (United States)

    Kapota, Dror; Dolev, Amit; Saltz, David

    2017-10-01

    The residence time is the amount of time spent within a predefined circle surrounding each point along the movement path of an animal, reflecting its response to resource availability/quality. Two main residence time-based methods exist in the literature: (1) The variance of residence times along the path plotted against the radius of the circle was suggested to indicate the scale at which the animal perceives its resources; and (2) segments of the path with homogeneous residence times were suggested to indicate distinct behavioral modes, at a certain scale. Here, we modify and integrate these two methods to one framework with two steps of analysis: (1) identifying several distinct, nested scales of area-restricted search (ARS), providing an indication of how animals view complex resource landscapes, and also the resolutions at which the analysis should proceed; and (2) identifying places which the animal revisits multiple times and performs ARS; for these, we extract two scale-dependent statistical measures-the mean visit duration and the number of revisits in each place. The association between these measures is suggested as a signature of how animals utilize different habitats or resource types. The framework is validated through computer simulations combining different movement strategies and resource maps. We suggest that the framework provides information that is especially relevant when interpreting movement data in light of optimal behavior models, and which would have remained uncovered by either coarser or finer analyses.

  5. Age and residence time of terrestrial source water in the northwest Atlantic shelf seas

    Science.gov (United States)

    He, R.; Todd, A. C.

    2016-02-01

    Coastal river mouths and bays are the junctions where terrestrial-source water meets and mixes with water from the open ocean. Once the riverine water reaches the coastal ocean, its eventual fate is largely unknown and difficult to trace. Rivers that flow into the ocean may contain high levels of nutrients and organic matter, so understanding the fate of terrestrial source water is important for a variety of biogeochemical processes that occur in the shelf seas. The fate of this terrestrial source water may be described in terms of its mean age (the time since it reached the ocean) and its residence time (the time it remains on the continental shelf). Using a high-resolution ocean model, we apply the constituent-oriented age and residence time (CART) theory to a large region encompassing the northwest Atlantic shelf seas to calculate the mean age of terrestrial source water and its residence time. For this application, 196 river mouths are used as sources of terrestrial water from South America to Nova Scotia. We investigate the spatial and seasonal variability of the water's mean age and compute the residence time within four different shelf regions: the Carribean Sea, the Gulf of Mexico, the South Atlantic Bight, and the Mid-Atlantic Bight/Gulf of Maine. From the estimates of mean age and residence time, we describe the impact of the coastal circulation on the eventual fate of terrestrial waters, and provide conjecture on how varying transport time scales may affect the general biogeochemical processes in the coastal ocean.

  6. Measurement of average continuous-time structure of a bond and ...

    African Journals Online (AJOL)

    The expected principal amount to be paid back per stock at time 't' was determined, while assuming that the present value of the stock follows a standard geometric ... When the interest rate of the bond was greater than the expected rate of return from the cash flow, then as 't' become larger, the cash flow grew with bound.

  7. Motional narrowing in the time-averaging approximation for simulating two-dimensional nonlinear infrared spectra

    NARCIS (Netherlands)

    Jansen, Thomas la Cour; Ruszel, Wioletta M.

    2008-01-01

    The diagonal linewidth in two-dimensional infrared spectra is often narrower than the distribution of transition frequencies. The width along the antidiagonal is broader than predicted by the lifetime broadening. These effects arise from time-dependent fluctuations of the transition frequencies.

  8. Particle residence times in waters of the Yangtze and Amazon continental shelves

    International Nuclear Information System (INIS)

    McKee, B.A.; Nittrouer, C.A.; DeMaster, D.J.

    1986-01-01

    Water column and seabed samples were analyzed for naturally occurring Th-234 to determine particle residence times in Yangtze and Amazon continental-shelf waters. On the Yangtze shelf, the water column was vertically well-mixed and suspended-sediment concentrations decreased offshore (from 230 mg/l near the river mouth to 2 mg/l in mid-shelf waters). Particle residence times increased offshore and ranged from 3.2 hours (12 m water depth) to 7.3 days (60 m water depth). Particle residence times ranged from 3 to 30 times shorter than values predicted by settling of discrete (4-8 micron) particles, suggesting that particles were settling in aggregate form. On the Amazon shelf, a two-layer estuarine flow dominated shelf circulation. Suspended-sediment concentrations on the inner shelf (10-12 m water depth) were much greater in bottom waters (range: 100-880 mg/l) than in surface waters (range 5-60 mg/l) as a result of resuspension. Particle residence times ranged from 1.1 days in surface waters to 2.5 days in bottom waters. Particles probably underwent several cycles of resuspension before permanent removal from the water column

  9. A High-Throughput Method for Measuring Drug Residence Time Using the Transcreener ADP Assay.

    Science.gov (United States)

    Kumar, Meera; Lowery, Robert G

    2017-08-01

    Analysis of drug-target residence times during drug development can result in improved efficacy, increased therapeutic window, and reduced side effects. Residence time can be estimated as the reciprocal of the dissociation rate ( k off ) of an inhibitor from its target. The traditional methods for measuring k off require synthesis of labeled ligands or low-throughput label-free methods. To provide an alternative that is better suited to an automated high-throughput screening (HTS) environment, we adapted a classic "jump dilution" catalytic assay method for determination of k off values for kinase inhibitor drugs. We used the Transcreener ADP 2 Kinase assay as a universal, homogenous method to monitor the recovery of kinase activity as the drugs dissociated from preformed inhibitor-kinase complexes. We measured residence times for several drugs that bind the epidermal growth factor receptor (EGFR), ABL1, and Aurora kinases and found that the rank ordering of inhibitor k off values correlated with literature values determined using ligand binding assays. Moreover, very similar results were obtained using the Transcreener assay with fluorescence polarization (FP), fluorescence intensity (FI), and time-resolved Förster resonance energy transfer (TR-FRET) detection modes. This HTS-compatible, generic assay method should facilitate the use of residence time as a parameter for compound prioritization and optimization early in kinase drug discovery programs.

  10. The role of residence time in diagnostic models of global carbon storage capacity: model decomposition based on a traceable scheme.

    Science.gov (United States)

    Yizhao, Chen; Jianyang, Xia; Zhengguo, Sun; Jianlong, Li; Yiqi, Luo; Chengcheng, Gang; Zhaoqi, Wang

    2015-11-06

    As a key factor that determines carbon storage capacity, residence time (τE) is not well constrained in terrestrial biosphere models. This factor is recognized as an important source of model uncertainty. In this study, to understand how τE influences terrestrial carbon storage prediction in diagnostic models, we introduced a model decomposition scheme in the Boreal Ecosystem Productivity Simulator (BEPS) and then compared it with a prognostic model. The result showed that τE ranged from 32.7 to 158.2 years. The baseline residence time (τ'E) was stable for each biome, ranging from 12 to 53.7 years for forest biomes and 4.2 to 5.3 years for non-forest biomes. The spatiotemporal variations in τE were mainly determined by the environmental scalar (ξ). By comparing models, we found that the BEPS uses a more detailed pool construction but rougher parameterization for carbon allocation and decomposition. With respect to ξ comparison, the global difference in the temperature scalar (ξt) averaged 0.045, whereas the moisture scalar (ξw) had a much larger variation, with an average of 0.312. We propose that further evaluations and improvements in τ'E and ξw predictions are essential to reduce the uncertainties in predicting carbon storage by the BEPS and similar diagnostic models.

  11. The role of residence time in diagnostic models of global carbon storage capacity: model decomposition based on a traceable scheme

    Science.gov (United States)

    Yizhao, Chen; Jianyang, Xia; Zhengguo, Sun; Jianlong, Li; Yiqi, Luo; Chengcheng, Gang; Zhaoqi, Wang

    2015-01-01

    As a key factor that determines carbon storage capacity, residence time (τE) is not well constrained in terrestrial biosphere models. This factor is recognized as an important source of model uncertainty. In this study, to understand how τE influences terrestrial carbon storage prediction in diagnostic models, we introduced a model decomposition scheme in the Boreal Ecosystem Productivity Simulator (BEPS) and then compared it with a prognostic model. The result showed that τE ranged from 32.7 to 158.2 years. The baseline residence time (τ′E) was stable for each biome, ranging from 12 to 53.7 years for forest biomes and 4.2 to 5.3 years for non-forest biomes. The spatiotemporal variations in τE were mainly determined by the environmental scalar (ξ). By comparing models, we found that the BEPS uses a more detailed pool construction but rougher parameterization for carbon allocation and decomposition. With respect to ξ comparison, the global difference in the temperature scalar (ξt) averaged 0.045, whereas the moisture scalar (ξw) had a much larger variation, with an average of 0.312. We propose that further evaluations and improvements in τ′E and ξw predictions are essential to reduce the uncertainties in predicting carbon storage by the BEPS and similar diagnostic models. PMID:26541245

  12. The effect of spatial randomness on the average fixation time of mutants

    Science.gov (United States)

    Farhang-Sardroodi, Suzan; Darooneh, Amir H.; Nikbakht, Moladad; Kohandel, Mohammad

    2017-01-01

    The mean conditional fixation time of a mutant is an important measure of stochastic population dynamics, widely studied in ecology and evolution. Here, we investigate the effect of spatial randomness on the mean conditional fixation time of mutants in a constant population of cells, N. Specifically, we assume that fitness values of wild type cells and mutants at different locations come from given probability distributions and do not change in time. We study spatial arrangements of cells on regular graphs with different degrees, from the circle to the complete graph, and vary assumptions on the fitness probability distributions. Some examples include: identical probability distributions for wild types and mutants; cases when only one of the cell types has random fitness values while the other has deterministic fitness; and cases where the mutants are advantaged or disadvantaged. Using analytical calculations and stochastic numerical simulations, we find that randomness has a strong impact on fixation time. In the case of complete graphs, randomness accelerates mutant fixation for all population sizes, and in the case of circular graphs, randomness delays mutant fixation for N larger than a threshold value (for small values of N, different behaviors are observed depending on the fitness distribution functions). These results emphasize fundamental differences in population dynamics under different assumptions on cell connectedness. They are explained by the existence of randomly occurring “dead zones” that can significantly delay fixation on networks with low connectivity; and by the existence of randomly occurring “lucky zones” that can facilitate fixation on networks of high connectivity. Results for death-birth and birth-death formulations of the Moran process, as well as for the (haploid) Wright Fisher model are presented. PMID:29176825

  13. Univariate Lp and lp Averaging, 0 p 1, in Polynomial Time by Utilization of Statistical Structure

    Science.gov (United States)

    2012-01-01

    civ@mail.mil; Tel.: +1-919-549-4253; Fax: +1-919-549-4354 2 Edward P. Fitts Department of Industrial and Systems Engineering, North Carolina State...by Utilization of Statistical Structure 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK...minimization problem by a polynomial-time linear programming procedure for minimizing l 1 functionals. When the data follow heavy-tailed statistical

  14. Variability in organic carbon reactivity across lake residence time and trophic gradients

    Science.gov (United States)

    Evans, Chris D.; Futter, Martyn N.; Moldan, Filip; Valinia, Salar; Frogbrook, Zoe; Kothawala, Dolly N.

    2017-11-01

    The transport of dissolved organic carbon from land to ocean is a large dynamic component of the global carbon cycle. Inland waters are hotspots for organic matter turnover, via both biological and photochemical processes, and mediate carbon transfer between land, oceans and atmosphere. However, predicting dissolved organic carbon reactivity remains problematic. Here we present in situ dissolved organic carbon budget data from 82 predominantly European and North American water bodies with varying nutrient concentrations and water residence times ranging from one week to 700 years. We find that trophic status strongly regulates whether water bodies act as net dissolved organic carbon sources or sinks, and that rates of both dissolved organic carbon production and consumption can be predicted from water residence time. Our results suggest a dominant role of rapid light-driven removal in water bodies with a short water residence time, whereas in water bodies with longer residence times, slower biotic production and consumption processes are dominant and counterbalance one another. Eutrophication caused lakes to transition from sinks to sources of dissolved organic carbon. We conclude that rates and locations of dissolved organic carbon processing and associated CO2 emissions in inland waters may be misrepresented in global carbon budgets if temporal and spatial reactivity gradients are not accounted for.

  15. Dynamics of nitrate production and removal as a function of residence time in the hyporheic zone

    Science.gov (United States)

    Jay P. Zarnetske; Roy Haggerty; Steven M. Wondzell; Michelle A. Baker

    2011-01-01

    Biogeochemical reactions associated with stream nitrogen cycling, such as nitrification and denitrification, can be strongly controlled by water and solute residence times in the hyporheic zone (HZ). We used a whole-stream steady state 15N-Iabeled nitrate and conservative tracer addition to investigate the spatial and temporal physiochemical...

  16. LABORATORY AND NUMERICAL INVESTIGATIONS OF RESIDENCE TIME DISTRIBUTION OF FLUIDS IN LAMINAR FLOW STIRRED ANNULAR PHOTOREACTOR

    Science.gov (United States)

    Laboratory and Numerical Investigations of Residence Time Distribution of Fluids in Laminar Flow Stirred Annular PhotoreactorE. Sahle-Demessie1, Siefu Bekele2, U. R. Pillai11U.S. EPA, National Risk Management Research LaboratorySustainable Technology Division,...

  17. Fertilizer residence time affects nitrogen uptake efficiency and growth of sweet corn

    NARCIS (Netherlands)

    Zotarelli, L.; Scholberg, J.M.S.; Dukes, M.D.; Munoz-Carpena, R.

    2008-01-01

    Understanding plant N uptake dynamics is critical for increasing fertilizer N uptake efficiency (FUE) and minimize the risk of N leaching. The objective of this research was to determine the effect of residence time of N fertilizer on N uptake and FUE of sweet corn. Plants were grown in 25 L columns

  18. Conceptual framework for model-based analysis of residence time distribution in twin-screw granulation.

    Science.gov (United States)

    Kumar, Ashish; Vercruysse, Jurgen; Vanhoorne, Valérie; Toiviainen, Maunu; Panouillot, Pierre-Emmanuel; Juuti, Mikko; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar

    2015-04-25

    Twin-screw granulation is a promising continuous alternative for traditional batchwise wet granulation processes. The twin-screw granulator (TSG) screws consist of transport and kneading element modules. Therefore, the granulation to a large extent is governed by the residence time distribution within each module where different granulation rate processes dominate over others. Currently, experimental data is used to determine the residence time distributions. In this study, a conceptual model based on classical chemical engineering methods is proposed to better understand and simulate the residence time distribution in a TSG. The experimental data were compared with the proposed most suitable conceptual model to estimate the parameters of the model and to analyse and predict the effects of changes in number of kneading discs and their stagger angle, screw speed and powder feed rate on residence time. The study established that the kneading block in the screw configuration acts as a plug-flow zone inside the granulator. Furthermore, it was found that a balance between the throughput force and conveying rate is required to obtain a good axial mixing inside the twin-screw granulator. Although the granulation behaviour is different for other excipients, the experimental data collection and modelling methods applied in this study are generic and can be adapted to other excipients. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Factors influencing the residence time of catchment waters : A virtual experiment approach

    NARCIS (Netherlands)

    Dunn, S.M.; McDonnell, J.J.; Vaché, K.B.

    Estimates of mean residence time (MRT) are increasingly used as simple summary descriptors of the hydrological processes involving storage and mixing of water within catchment systems. Current understanding of the physical controls on MRT remains limited, and various hypotheses have been proposed to

  20. Residence times of alluvium in an east Texas stream as indicated by sediment color

    Science.gov (United States)

    Jonathan D. Phillips; Daniel A. Marion

    2001-01-01

    The relationships between sediment production, storage, and transport in fluvial systems are complex and variable. Key issues in addressing these relationships are the residence times of sediment delivered to the channel, and the proportion derived from recent upland erosion as opposed to remobilized alluvium. The systematic changes in iron geochemistry often...

  1. Residence time controls on nitrogen transformations in a permeable nearshore aquifer

    Science.gov (United States)

    Robinson, C. E.

    2015-12-01

    Permeable nearshore aquifers are an important biogeochemical hotspot for nitrogen (N) cycling. Located at the land-sea interface this hotspot has been shown to regulate N fluxes to coastal waters via submarine groundwater discharge. N transformations in a nearshore aquifer may result in either a net production or net removal of NO3- with the transformations controlled by complex interacting physical transport and biogeochemical kinetic processes. Oceanic forcing including tides and waves cause large quantities of seawater and chemical constituents, including dissolved oxygen and organic matter, to recirculate through the nearshore aquifer. There is currently limited understanding of the impact of the oceanic forcing on the residence time of recirculating constituents and the subsequent implications on N transformations in the aquifer. A numerical model was applied to quantify the influence of varying tidal and wave conditions on residence times and evaluate how the interactions between the coupled transport and reaction kinetics control N transformations and fluxes. Simulations were performed using the variable-density groundwater flow model SEAWAT-2005 combined with the reactive multi-component transport model PHT3D v2.10. The model simulated the transport and transformation of both marine- and land-derived chemical consitituents and considered oxic DOM mineralization, nitrification and denitrification. Simulations demonstrate that the recirculation residence times, combined with oxygen removal rates, regulate whether a nearshore aquifer will act as a net source or sink of NO3. Dimensionless Damköhler numbers calculated as the ratio of the characteristic residence time to characterisitic oxygen reaction time were determined and provide valuable insight into the residence time controls on the ultimate flux of N to the sea.

  2. Timed Up And Go Risk Predictor Of Falls In Elderly People Residing In The Community?

    Directory of Open Access Journals (Sweden)

    Mayara Muniz Peixoto Rodrigues

    2017-04-01

    Full Text Available Objective: evaluate the risk of falls of elderly people residing in a community in northeastern Brazil using the “Timed up and go”. Method: descriptive study, with a quantitative approach, performed with elderly people residing in a community. The collected data related to the sociodemographic and economic characteristics of episodes of falls in the last two years, regular practice of physical exercise and complaint of pain at the time of the interview; and, at last, the application of the “Timed Up and Go” test. Result: Most of the elderly were classified as free and independent and independent. There is a direct relationship between advanced age and increased time to perform the test. Conclusion: the "Timed Up and Go" test was not effective in predicting risk of falls alone and should associate with other indicators. Descriptors: Elderly people; Accidents by fall; Walking; Postural balance.

  3. The role of residence times in two-patch dengue transmission dynamics and optimal strategies.

    Science.gov (United States)

    Lee, Sunmi; Castillo-Chavez, Carlos

    2015-06-07

    The reemergence and geographical dispersal of vector-borne diseases challenge global health experts around the world and in particular, dengue poses increasing difficulties in the Americas, due in part to explosive urban and semi-urban growth, increases of within and between region mobility, the absence of a vaccine, and the limited resources available for public health services. In this work, a simple deterministic two-patch model is introduced to assess the impact of dengue transmission dynamics in heterogeneous environments. The two-patch system models the movement (e.g. urban versus rural areas residence times) of individuals between and within patches/environments using residence-time matrices with entries that budget within and between host patch relative residence times, under the assumption that only the human budgets their residence time across regions. Three scenarios are considered: (i) resident hosts in Patch i visit patch j, where i≠j but not the other way around, a scenario referred to as unidirectional motion; (ii) symmetric bi-directional motion; and (iii) asymmetric bi-directional motion. Optimal control theory is used to identify and evaluate patch-specific control measures aimed at reducing dengue prevalence in humans and vectors at a minimal cost. Optimal policies are computed under different residence-matrix configurations mentioned above as well as transmissibility scenarios characterized by the magnitude of the basic reproduction number. Optimal patch-specific polices can ameliorate the impact of epidemic outbreaks substantially when the basic reproduction number is moderate. The final patch-specific epidemic size variation increases as the residence time matrix moves away from the symmetric case (asymmetry). As expected, the patch where individuals spend most of their time or in the patch where transmissibility is higher tend to support larger patch-specific final epidemic sizes. Hence, focusing on intervention that target areas where

  4. Forecasting Final Energy Consumption using the Centered Moving Average Method and Time Series Analysis

    Directory of Open Access Journals (Sweden)

    Janina POPEANGA

    2014-05-01

    Full Text Available The forecasting of energy consumption has become one of the major fields of research in recent years. Accurate energy demand forecasting is essential in energy system operations and planning. In this paper, we will describe a method to determine the information that is useful for a good forecasting. Further, we adopt the time series modeling approach to model final energy consumption in Romania using previous data of 2010 to 2013. This method is implemented using stored procedures, developed in Oracle PL/SQL programming language. Finally, the developed model is compared for goodness of fit to the historical data and forecasting accuracy, and results are encouraging, showing that the forecast model is in control and is working correctly.

  5. On the average complexity of sphere decoding in lattice space-time coded multiple-input multiple-output channel

    KAUST Repository

    Abediseid, Walid

    2012-12-21

    The exact average complexity analysis of the basic sphere decoder for general space-time codes applied to multiple-input multiple-output (MIMO) wireless channel is known to be difficult. In this work, we shed the light on the computational complexity of sphere decoding for the quasi- static, lattice space-time (LAST) coded MIMO channel. Specifically, we drive an upper bound of the tail distribution of the decoder\\'s computational complexity. We show that when the computational complexity exceeds a certain limit, this upper bound becomes dominated by the outage probability achieved by LAST coding and sphere decoding schemes. We then calculate the minimum average computational complexity that is required by the decoder to achieve near optimal performance in terms of the system parameters. Our results indicate that there exists a cut-off rate (multiplexing gain) for which the average complexity remains bounded. Copyright © 2012 John Wiley & Sons, Ltd.

  6. How Entrustment Is Informed by Holistic Judgments Across Time in a Family Medicine Residency Program: An Ethnographic Nonparticipant Observational Study.

    Science.gov (United States)

    Sagasser, Margaretha H; Fluit, Cornelia R M G; van Weel, Chris; van der Vleuten, Cees P M; Kramer, Anneke W M

    2017-06-01

    Entrustment has mainly been conceptualized as delegating discrete professional tasks. Because residents provide most of their patient care independently, not all resident performance is visible to supervisors; the entrustment process involves more than granting discrete tasks. This study explored how supervisors made entrustment decisions based on residents' performance in a long-term family medicine training program. A qualitative nonparticipant observational study was conducted in 2014-2015 at competency-based family medicine residency programs in the Netherlands. Seven supervisor-resident pairs participated. During two days, one researcher observed first-year residents' patient encounters, debriefing sessions, and supervisor-resident educational meetings and interviewed them separately afterwards. Data were collected and analyzed using iterative, phenomenological inductive research methodology. The entrustment process developed over three phases. Supervisors based their initial entrustment on prior knowledge about the resident. In the ensuing two weeks, entrustment decisions regarding independent patient care were derived from residents' observed general competencies necessary for a range of health problems (clinical reasoning, decision making, relating to patients); medical knowledge and skills; and supervisors' intuition. Supervisors provided supervision during and after encounters. Once residents performed independently, supervisors kept reevaluating their decisions, informed by residents' overall growth in competencies rather than by adhering to a predefined set of tasks. Supervisors in family medicine residency training took a holistic approach to trust, based on general competencies, knowledge, skills, and intuition. Entrustment started before training and developed over time. Building trust is a mutual process between supervisor and resident, requiring a good working relationship.

  7. Univariate Lp and ɭ p Averaging, 0 < p < 1, in Polynomial Time by Utilization of Statistical Structure

    Directory of Open Access Journals (Sweden)

    John E. Lavery

    2012-10-01

    Full Text Available We present evidence that one can calculate generically combinatorially expensive Lp and lp averages, 0 < p < 1, in polynomial time by restricting the data to come from a wide class of statistical distributions. Our approach differs from the approaches in the previous literature, which are based on a priori sparsity requirements or on accepting a local minimum as a replacement for a global minimum. The functionals by which Lp averages are calculated are not convex but are radially monotonic and the functionals by which lp averages are calculated are nearly so, which are the keys to solvability in polynomial time. Analytical results for symmetric, radially monotonic univariate distributions are presented. An algorithm for univariate lp averaging is presented. Computational results for a Gaussian distribution, a class of symmetric heavy-tailed distributions and a class of asymmetric heavy-tailed distributions are presented. Many phenomena in human-based areas are increasingly known to be represented by data that have large numbers of outliers and belong to very heavy-tailed distributions. When tails of distributions are so heavy that even medians (L1 and l1 averages do not exist, one needs to consider using lp minimization principles with 0 < p < 1.

  8. Detection of hidden stationary deformations of vibrating surfaces by use of time-averaged digital holographic interferometry.

    Science.gov (United States)

    Demoli, Nazif; Vukicevic, Dalibor

    2004-10-15

    A method of detecting displacements of a surface from its steady-state position to its equilibrium position while it is vibrating has been developed by use of time-average digital holographic interferometry. This method permits extraction of such a hidden deformation by creating two separated systems of interferogram fringes: one corresponding to a time-varying resonantly oscillating optical phase, the other to the stationary phase modification. A mathematical description of the method and illustrative results of experimental verification are presented.

  9. Sustained increase in resident meal time hand hygiene through an interdisciplinary intervention engaging long-term care facility residents and staff.

    Science.gov (United States)

    O'Donnell, Marguerite; Harris, Tony; Horn, Terancita; Midamba, Blondelle; Primes, Vickie; Sullivan, Nancy; Shuler, Rosalyn; Zabarsky, Trina F; Deshpande, Abhishek; Sunkesula, Venkata C K; Kundrapu, Sirisha; Donskey, Curtis J

    2015-02-01

    Hand hygiene by patients may prevent acquisition and dissemination of health care-associated pathogens, but limited efforts have been made to engage patients in hand hygiene interventions. In a long-term care facility, we found that residents were aware of the importance of hand hygiene, but barriers, such as inaccessible products or difficult to use products, limited compliance. A dramatic and sustained improvement in meal time hand hygiene was achieved through engagement of staff and residents. Published by Elsevier Inc.

  10. Uncertainties in carbon residence time and NPP-driven carbon uptake in terrestrial ecosystems of the conterminous USA: a Bayesian approach

    Directory of Open Access Journals (Sweden)

    Xuhui Zhou

    2012-10-01

    Full Text Available Carbon (C residence time is one of the key factors that determine the capacity of ecosystem C storage. However, its uncertainties have not been well quantified, especially at regional scales. Assessing uncertainties of C residence time is thus crucial for an improved understanding of terrestrial C sequestration. In this study, the Bayesian inversion and Markov Chain Monte Carlo (MCMC technique were applied to a regional terrestrial ecosystem (TECO-R model to quantify C residence times and net primary productivity (NPP-driven ecosystem C uptake and assess their uncertainties in the conterminous USA. The uncertainty was represented by coefficient of variation (CV. The 13 spatially distributed data sets of C pools and fluxes have been used to constrain TECO-R model for each biome (totally eight biomes. Our results showed that estimated ecosystem C residence times ranged from 16.6±1.8 (cropland to 85.9±15.3 yr (evergreen needleleaf forest with an average of 56.8±8.8 yr in the conterminous USA. The ecosystem C residence times and their CV were spatially heterogeneous and varied with vegetation types and climate conditions. Large uncertainties appeared in the southern and eastern USA. Driven by NPP changes from 1982 to 1998, terrestrial ecosystems in the conterminous USA would absorb 0.20±0.06 Pg C yr−1. Their spatial pattern was closely related to the greenness map in the summer with larger uptake in central and southeast regions. The lack of data or timescale mismatching between the available data and the estimated parameters lead to uncertainties in the estimated C residence times, which together with initial NPP resulted in the uncertainties in the estimated NPP-driven C uptake. The Bayesian approach with MCMC inversion provides an effective tool to estimate spatially distributed C residence time and assess their uncertainties in the conterminous USA.

  11. A review of radioactive isotopes and other residence time tracers in understanding groundwater recharge: Possibilities, challenges, and limitations

    Science.gov (United States)

    Cartwright, Ian; Cendón, Dioni; Currell, Matthew; Meredith, Karina

    2017-12-01

    Documenting the location and magnitude of groundwater recharge is critical for understanding groundwater flow systems. Radioactive tracers, notably 14C, 3H, 36Cl, and the noble gases, together with other tracers whose concentrations vary over time, such as the chlorofluorocarbons or sulfur hexafluoride, are commonly used to estimate recharge rates. This review discusses some of the advantages and problems of using these tracers to estimate recharge rates. The suite of tracers allows recharge to be estimated over timescales ranging from a few years to several hundred thousand years, which allows both the long-term and modern behaviour of groundwater systems to be documented. All tracers record mean residence times and mean recharge rates rather than a specific age and date of recharge. The timescale over which recharge rates are averaged increases with the mean residence time. This is an advantage in providing representative recharge rates but presents a problem in comparing recharge rates derived from these tracers with those from other techniques, such as water table fluctuations or lysimeters. In addition to issues relating to the sampling and interpretation of specific tracers, macroscopic dispersion and mixing in groundwater flow systems limit how precisely groundwater residence times and recharge rates may be estimated. Additionally, many recharge studies have utilised existing infrastructure that may not be ideal for this purpose (e.g., wells with long screens that sample groundwater several kilometres from the recharge area). Ideal recharge studies would collect sufficient information to optimise the use of specific tracers and minimise the problems of mixing and dispersion.

  12. Reducing the residence time of a bouncing drop with spoked macrotexture

    Science.gov (United States)

    Patterson, Colin; Bird, James

    2015-11-01

    Liquid drops can bounce when they impact non-wetting surfaces. Recently, studies have demonstrated that the time that the bouncing drop resides at the surface can be adjusted with the presence of ridged macrotextures. When non-parallel macrotextures are present, they intersect to create spoked junctions. At sufficient velocity, a drop impacting a junction might be expected to breakup into smaller droplets; yet it is unclear how many droplets would be produced and the time for these droplets to clear the surface. Here, we show that the number droplets and overall residence time depends on both the number of spokes and the Weber number. We experimentally demonstrate that the center-assisted recoil framework extends beyond superhydrophobic surfaces to those above the Leidenfrost temperature. Finally, we present a physical model that rationalizes our results.

  13. Non-invasive assessment of distribution volume ratios and binding potential: tissue heterogeneity and interindividually averaged time-activity curves

    Energy Technology Data Exchange (ETDEWEB)

    Reimold, M.; Mueller-Schauenburg, W.; Dohmen, B.M.; Bares, R. [Department of Nuclear Medicine, University of Tuebingen, Otfried-Mueller-Strasse 14, 72076, Tuebingen (Germany); Becker, G.A. [Nuclear Medicine, University of Leipzig, Leipzig (Germany); Reischl, G. [Radiopharmacy, University of Tuebingen, Tuebingen (Germany)

    2004-04-01

    Due to the stochastic nature of radioactive decay, any measurement of radioactivity concentration requires spatial averaging. In pharmacokinetic analysis of time-activity curves (TAC), such averaging over heterogeneous tissues may introduce a systematic error (heterogeneity error) but may also improve the accuracy and precision of parameter estimation. In addition to spatial averaging (inevitable due to limited scanner resolution and intended in ROI analysis), interindividual averaging may theoretically be beneficial, too. The aim of this study was to investigate the effect of such averaging on the binding potential (BP) calculated with Logan's non-invasive graphical analysis and the ''simplified reference tissue method'' (SRTM) proposed by Lammertsma and Hume, on the basis of simulated and measured positron emission tomography data [{sup 11}C]d-threo-methylphenidate (dMP) and [{sup 11}C]raclopride (RAC) PET. dMP was not quantified with SRTM since the low k {sub 2} (washout rate constant from the first tissue compartment) introduced a high noise sensitivity. Even for considerably different shapes of TAC (dMP PET in parkinsonian patients and healthy controls, [{sup 11}C]raclopride in patients with and without haloperidol medication) and a high variance in the rate constants (e.g. simulated standard deviation of K {sub 1}=25%), the BP obtained from average TAC was close to the mean BP (<5%). However, unfavourably distributed parameters, especially a correlated large variance in two or more parameters, may lead to larger errors. In Monte Carlo simulations, interindividual averaging before quantification reduced the variance from the SRTM (beyond a critical signal to noise ratio) and the bias in Logan's method. Interindividual averaging may further increase accuracy when there is an error term in the reference tissue assumption E=DV {sub 2}-DV ' (DV {sub 2} = distribution volume of the first tissue compartment, DV &apos

  14. Using continuous underway isotope measurements to map water residence time in hydrodynamically complex tidal environments

    Science.gov (United States)

    Downing, Bryan D.; Bergamaschi, Brian; Kendall, Carol; Kraus, Tamara; Dennis, Kate J.; Carter, Jeffery A.; von Dessonneck, Travis

    2016-01-01

    Stable isotopes present in water (δ2H, δ18O) have been used extensively to evaluate hydrological processes on the basis of parameters such as evaporation, precipitation, mixing, and residence time. In estuarine aquatic habitats, residence time (τ) is a major driver of biogeochemical processes, affecting trophic subsidies and conditions in fish-spawning habitats. But τ is highly variable in estuaries, owing to constant changes in river inflows, tides, wind, and water height, all of which combine to affect τ in unpredictable ways. It recently became feasible to measure δ2H and δ18O continuously, at a high sampling frequency (1 Hz), using diffusion sample introduction into a cavity ring-down spectrometer. To better understand the relationship of τ to biogeochemical processes in a dynamic estuarine system, we continuously measured δ2H and δ18O, nitrate and water quality parameters, on board a small, high-speed boat (5 to >10 m s–1) fitted with a hull-mounted underwater intake. We then calculated τ as is classically done using the isotopic signals of evaporation. The result was high-resolution (∼10 m) maps of residence time, nitrate, and other parameters that showed strong spatial gradients corresponding to geomorphic attributes of the different channels in the area. The mean measured value of τ was 30.5 d, with a range of 0–50 d. We used the measured spatial gradients in both τ and nitrate to calculate whole-ecosystem uptake rates, and the values ranged from 0.006 to 0.039 d–1. The capability to measure residence time over single tidal cycles in estuaries will be useful for evaluating and further understanding drivers of phytoplankton abundance, resolving differences attributable to mixing and water sources, explicitly calculating biogeochemical rates, and exploring the complex linkages among time-dependent biogeochemical processes in hydrodynamically complex environments such as estuaries.

  15. Does residence time affect responses of alien species richness to environmental and spatial processes?

    Directory of Open Access Journals (Sweden)

    Matteo Dainese

    2012-08-01

    Full Text Available One of the most robust emerging generalisations in invasion biology is that the probability of invasion increases with the time since introduction (residence time. We analysed the spatial distribution of alien vascular plant species in a region of north-eastern Italy to understand the influence of residence time on patterns of alien species richness. Neophytes were grouped according to three periods of arrival in the study region (1500–1800, 1800–1900, and > 1900. We applied multiple regression (spatial and non-spatial with hierarchical partitioning to determine the influence of climate and human pressure on species richness within the groups. We also applied variation partitioning to evaluate the relative importance of environmental and spatial processes. Temperature mainly influenced groups with speciesa longer residence time, while human pressure influenced the more recently introduced species, although its influence remained significant in all groups. Partial regression analyses showed that most of the variation explained by the models is attributable to spatially structured environmental variation, while environment and space had small independent effects. However, effects independent of environment decreased, and spatially independent effects increased, from older to the more recent neophytes. Our data illustrate that the distribution of alien species richness for species that arrived recently is related to propagule pressure, availability of novel niches created by human activity, and neutral-based (dispersal limitation processes, while climate filtering plays a key role in the distribution of species that arrived earlier. This study highlights the importance of residence time, spatial structure, and environmental conditions in the patterns of alien species richness and for a better understanding of its geographical variation.

  16. Characterizing Drug-Target Residence Time with Metadynamics: How To Achieve Dissociation Rate Efficiently without Losing Accuracy against Time-Consuming Approaches.

    Science.gov (United States)

    Sun, Huiyong; Li, Youyong; Shen, Mingyun; Li, Dan; Kang, Yu; Hou, Tingjun

    2017-08-28

    Drug-target residence time plays a vital role in drug efficacy. However, there is still no effective strategy to predict drug residence time. Here, we propose to use the optimized (or minimized) structures derived from holo-state proteins to calculate drug residence time, which could give a comparable or even better prediction accuracy compared with those calculated utilizing a large number of molecular dynamics (MD) structures based on the Poisson process. Besides, in addition to the Poisson process, one may use fewer samples for predicting residence time due to the reason that, in a large extent, the calculated drug residence time is stable and independent of the number of samples used for the prediction. With remarkably reduced computational load, the proposed strategy may be promising for large-scale drug residence time prediction, such as post-processing in virtual screening (VS) and lead compound optimization.

  17. Classification of Animal Movement Behavior through Residence in Space and Time.

    Science.gov (United States)

    Torres, Leigh G; Orben, Rachael A; Tolkova, Irina; Thompson, David R

    2017-01-01

    Identification and classification of behavior states in animal movement data can be complex, temporally biased, time-intensive, scale-dependent, and unstandardized across studies and taxa. Large movement datasets are increasingly common and there is a need for efficient methods of data exploration that adjust to the individual variability of each track. We present the Residence in Space and Time (RST) method to classify behavior patterns in movement data based on the concept that behavior states can be partitioned by the amount of space and time occupied in an area of constant scale. Using normalized values of Residence Time and Residence Distance within a constant search radius, RST is able to differentiate behavior patterns that are time-intensive (e.g., rest), time & distance-intensive (e.g., area restricted search), and transit (short time and distance). We use grey-headed albatross (Thalassarche chrysostoma) GPS tracks to demonstrate RST's ability to classify behavior patterns and adjust to the inherent scale and individuality of each track. Next, we evaluate RST's ability to discriminate between behavior states relative to other classical movement metrics. We then temporally sub-sample albatross track data to illustrate RST's response to less resolved data. Finally, we evaluate RST's performance using datasets from four taxa with diverse ecology, functional scales, ecosystems, and data-types. We conclude that RST is a robust, rapid, and flexible method for detailed exploratory analysis and meta-analyses of behavioral states in animal movement data based on its ability to integrate distance and time measurements into one descriptive metric of behavior groupings. Given the increasing amount of animal movement data collected, it is timely and useful to implement a consistent metric of behavior classification to enable efficient and comparative analyses. Overall, the application of RST to objectively explore and compare behavior patterns in movement data can

  18. Classification of Animal Movement Behavior through Residence in Space and Time.

    Directory of Open Access Journals (Sweden)

    Leigh G Torres

    Full Text Available Identification and classification of behavior states in animal movement data can be complex, temporally biased, time-intensive, scale-dependent, and unstandardized across studies and taxa. Large movement datasets are increasingly common and there is a need for efficient methods of data exploration that adjust to the individual variability of each track. We present the Residence in Space and Time (RST method to classify behavior patterns in movement data based on the concept that behavior states can be partitioned by the amount of space and time occupied in an area of constant scale. Using normalized values of Residence Time and Residence Distance within a constant search radius, RST is able to differentiate behavior patterns that are time-intensive (e.g., rest, time & distance-intensive (e.g., area restricted search, and transit (short time and distance. We use grey-headed albatross (Thalassarche chrysostoma GPS tracks to demonstrate RST's ability to classify behavior patterns and adjust to the inherent scale and individuality of each track. Next, we evaluate RST's ability to discriminate between behavior states relative to other classical movement metrics. We then temporally sub-sample albatross track data to illustrate RST's response to less resolved data. Finally, we evaluate RST's performance using datasets from four taxa with diverse ecology, functional scales, ecosystems, and data-types. We conclude that RST is a robust, rapid, and flexible method for detailed exploratory analysis and meta-analyses of behavioral states in animal movement data based on its ability to integrate distance and time measurements into one descriptive metric of behavior groupings. Given the increasing amount of animal movement data collected, it is timely and useful to implement a consistent metric of behavior classification to enable efficient and comparative analyses. Overall, the application of RST to objectively explore and compare behavior patterns in

  19. The use of 41Ar to investigate residence time distribution (RTD) in petrochemical industry

    International Nuclear Information System (INIS)

    Sirelkhatim, D. A.; Hassan, B. A.; ElTayeb, M. A. H.; Hills, A. E.

    2004-01-01

    Residence time measurements were carried out on a wax slurry bed reactor (SBR) and on a pilot FTDU reactor by means of radioisotope tracer technology using Ar-41 as tracer gas. Representative results were obtained as the behaviour of the gas in the SBR showed channeling downstream and in the FTDU, possible different mixing zones in the upper portion and the occurrence of air pockets was evident. ( Authors)

  20. Extra-regional residence time as a correlate of plant invasiveness: European archaeophytes in North America

    Czech Academy of Sciences Publication Activity Database

    La Sorte, F. A.; Pyšek, Petr

    2009-01-01

    Roč. 90, č. 9 (2009), s. 2589-2597 ISSN 0012-9658 R&D Projects: GA MŠk LC06073 Grant - others:Evropská komise(XE) GOCE-CT-2003-506675 Institutional research plan: CEZ:AV0Z60050516 Keywords : residence time * archaeophyte * North America Subject RIV: EF - Botanics Impact factor: 4.411, year: 2009

  1. Residence Time Distribution (RTD) Prediction in Mixing Vessel via CFD Simulation Using Fluent: An Overview

    International Nuclear Information System (INIS)

    Mohd Rizal Mamat; Azraf Azman; Noraishah Othman

    2011-01-01

    A prototype mixing vessel has been developed by Industrial Technology Division and installed at a multiphase testing facility in MINT Tech Park. A task to investigate the mixing vessel performance using Computational Fluid Dynamics (CFD) has been undertaken using the available FLUENT software in Malaysian Nuclear Agency. This paper discusses the modeling and simulation done in obtaining the Residence Time Distribution (RTD) for the mixing vessel using FLUENT. (author)

  2. Determination of the hydraulic residence time of two subsurface-flow constructed wetlands using radiotracers

    International Nuclear Information System (INIS)

    Debien, Bruno R.

    2013-01-01

    The adoption of constructed wetland systems (CW's) with subsuperficial drainage for sewage treatment is increasingly growing in places with low technological resources and available land. The efficient removal of pollutants depends on the internal flow characteristics in the CW and on its hydraulic residence time (HRT). In the present work 82 Br - a gamma radiation emitter, produced from soluble potassium bromide irradiated in the TRIGA reactor at the Centre for the Development of Nuclear Energy (CDTN) - was used as a pseudo-conservative tracer for the comparative study of aqueous phase flow dynamics in two CW's: one in which plants were grown (WP) whereas the other had no plants (WNP). Experimental hydraulic residence time values were found to be very close to the theoretical one, while dispersion numbers obtained for both CW's were quite small. Besides these measured hydrodynamic parameters, the residence time distribution (RTD) curves of the tracer test and the results of modeling of experimental data also demonstrate the tendency of the units to display a plug flow-like effluent hydraulic transport within their systems, as expected from their designs, considering the large length/width ratio (L/W=8). (author)

  3. Impacts of residence time during storage on potential of water saving for grey water recycling system.

    Science.gov (United States)

    Liu, S; Butler, D; Memon, F A; Makropoulos, C; Avery, L; Jefferson, B

    2010-01-01

    Grey water recycling has been generally accepted and is about to move into practice in terms of sustainable development. Previous research has revealed the bacteria re-growth in grey water and reclaimed municipal water during storage. However, in most present grey water recycling practices, impacts of water quality changes during storage on the system's performance and design regulation have not been addressed. In this paper, performance of a constructed wetland based grey water recycling system was analysed by taking the constraint of residence time during storage into account using an object based household water cycle model. Two indicators, water saving efficiency (WSE) and residence time index (RTI), are employed to reflect the system's performance and residence time during storage respectively. Results show that WSE and RTI change with storage tank volumes oppositely. As both high WSE and RTI cannot be achieved simultaneously, it is concluded that in order to achieve the most cost-effective and safe solution, systems with both small grey and green tanks are needed, whilst accepting that only relatively modest water saving efficiency targets can be achieved. Higher efficiencies will only be practicable if water quality deterioration in the green water tank can be prevented by some means (e.g. disinfection).

  4. Residence time, native range size, and genome size predict naturalization among angiosperms introduced to Australia.

    Science.gov (United States)

    Schmidt, John P; Drake, John M; Stephens, Patrick

    2017-12-01

    Although critical to progress in understanding (i) if, and (ii) at what rate, introduced plants will naturalize and potentially become invasive, establishing causal links between traits and invasion success is complicated by data gaps, phylogenetic nonindependence of species, the inability to control for differences between species in residence time and propagule pressure, and covariance among traits. Here, we focus on statistical relationships between genomic factors, life history traits, native range size, and naturalization status of angiosperms introduced to Australia. In a series of analyses, we alternately investigate the role of phylogeny, incorporate introduction history, and use graphical models to explore the network of conditional probabilities linking traits and introduction history to naturalization status. Applying this ensemble of methods to the largest publicly available data set on plant introductions and their fates, we found that, overall, residence time and native range size best predicted probability of naturalization. Yet, importantly, probability of naturalization consistently increased as genome size decreased, even when the effects of shared ancestry and residence time in Australia were accounted for, and that this pattern was stronger in species without a history of cultivation, but present across annual-biennials, and herbaceous and woody perennials. Thus, despite introduction biases and indirect effects of traits via introduction history, across analyses, reduced genome size was nevertheless consistently associated with a tendency to naturalize.

  5. The relative importance of water temperature and residence time in predicting cyanobacteria abundance in regulated rivers.

    Science.gov (United States)

    Cha, YoonKyung; Cho, Kyung Hwa; Lee, Hyuk; Kang, Taegu; Kim, Joon Ha

    2017-11-01

    Despite a growing awareness of the problems associated with cyanobacterial blooms in rivers, and particularly in regulated rivers, the drivers of bloom formation and abundance in rivers are not well understood. We developed a Bayesian hierarchical model to assess the relative importance of predictors of summer cyanobacteria abundance, and to test whether the relative importance of each predictor varies by site, using monitoring data from 16 sites in the four major rivers of South Korea. The results suggested that temperature and residence time, but not nutrient levels, are important predictors of summer cyanobacteria abundance in rivers. Although the two predictors were of similar significance across the sites, the residence time was marginally better in accounting for the variation in cyanobacteria abundance. The model with spatial hierarchy demonstrated that temperature played a consistently significant role at all sites, and showed no effect from site-specific factors. In contrast, the importance of residence time varied significantly from site to site. This variation was shown to depend on the trophic state, indicated by the chlorophyll-a and total phosphorus levels. Our results also suggested that the magnitude of weir inflow is a key factor determining the cyanobacteria abundance under baseline conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Determination of the hydraulic residence time of two subsurface-flow constructed wetlands using radiotracers

    Energy Technology Data Exchange (ETDEWEB)

    Debien, Bruno R., E-mail: brunordebien@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept de Geografia. Lab. de Geomorfologia; Barreto, Alberto A.; Pinto, Amenonia M.F.; Moreira, Rubens M., E-mail: aab@cdtn.br, E-mail: amfp@cdtn.br, E-mail: rubens@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    The adoption of constructed wetland systems (CW's) with subsuperficial drainage for sewage treatment is increasingly growing in places with low technological resources and available land. The efficient removal of pollutants depends on the internal flow characteristics in the CW and on its hydraulic residence time (HRT). In the present work {sup 82}Br - a gamma radiation emitter, produced from soluble potassium bromide irradiated in the TRIGA reactor at the Centre for the Development of Nuclear Energy (CDTN) - was used as a pseudo-conservative tracer for the comparative study of aqueous phase flow dynamics in two CW's: one in which plants were grown (WP) whereas the other had no plants (WNP). Experimental hydraulic residence time values were found to be very close to the theoretical one, while dispersion numbers obtained for both CW's were quite small. Besides these measured hydrodynamic parameters, the residence time distribution (RTD) curves of the tracer test and the results of modeling of experimental data also demonstrate the tendency of the units to display a plug flow-like effluent hydraulic transport within their systems, as expected from their designs, considering the large length/width ratio (L/W=8). (author)

  7. Estimating Estuarine Residence Times in the Westerschelde (the Netherlands) Using a Box Model with Fixed Dispersion Coefficients

    NARCIS (Netherlands)

    Soetaert, K.E.R.; Herman, P.M.J.

    1995-01-01

    The residence time of the water masses in the Westerschelde estuary was determined using a simple compartment-model that simulates the advective-diffusive transport of a conservative dissolved substance (chlorinity). The residence time of a water parcel in the upstream part of the estuary (i.e, the

  8. Water availability limits tree productivity, carbon stocks, and carbon residence time in mature forests across the western US

    Science.gov (United States)

    Berner, Logan T.; Law, Beverly E.; Hudiburg, Tara W.

    2017-01-01

    Water availability constrains the structure and function of terrestrial ecosystems and is projected to change in many parts of the world over the coming century. We quantified the response of tree net primary productivity (NPP), live biomass (BIO), and mean carbon residence time (CRT = BIO / NPP) to spatial variation in water availability in the western US. We used forest inventory measurements from 1953 mature stands (> 100 years) in Washington, Oregon, and California (WAORCA) along with satellite and climate data sets covering the western US. We summarized forest structure and function in both domains along a 400 cm yr-1 hydrologic gradient, quantified with a climate moisture index (CMI) based on the difference between precipitation and reference evapotranspiration summed over the water year (October-September) and then averaged annually from 1985 to 2014 (CMIwy). Median NPP, BIO, and CRT computed at 10 cm yr-1 intervals along the CMIwy gradient increased monotonically with increasing CMIwy across both WAORCA (rs = 0.93-0.96, p the western US (rs = 0.93-0.99, p the driest and wettest 5 % of sites, while BIO increased from 26 to 281 Mg C ha-1 and CRT increased from 11 to 49 years. The satellite data sets revealed similar changes over the western US, though these data sets tended to plateau in the wettest areas, suggesting that additional efforts are needed to better quantify NPP and BIO from satellites in high-productivity, high-biomass forests. Our results illustrate that long-term average water availability is a key environmental constraint on tree productivity, carbon storage, and carbon residence time in mature forests across the western US, underscoring the need to assess potential ecosystem response to projected warming and drying over the coming century.

  9. Root microbiota dynamics of perennial Arabis alpina are dependent on soil residence time but independent of flowering time.

    Science.gov (United States)

    Dombrowski, Nina; Schlaeppi, Klaus; Agler, Matthew T; Hacquard, Stéphane; Kemen, Eric; Garrido-Oter, Ruben; Wunder, Jörg; Coupland, George; Schulze-Lefert, Paul

    2017-01-01

    Recent field and laboratory experiments with perennial Boechera stricta and annual Arabidopsis thaliana suggest that the root microbiota influences flowering time. Here we examined in long-term time-course experiments the bacterial root microbiota of the arctic-alpine perennial Arabis alpina in natural and controlled environments by 16S rRNA gene profiling. We identified soil type and residence time of plants in soil as major determinants explaining up to 15% of root microbiota variation, whereas environmental conditions and host genotype explain maximally 11% of variation. When grown in the same soil, the root microbiota composition of perennial A. alpina is largely similar to those of its annual relatives A. thaliana and Cardamine hirsuta. Non-flowering wild-type A. alpina and flowering pep1 mutant plants assemble an essentially indistinguishable root microbiota, thereby uncoupling flowering time from plant residence time-dependent microbiota changes. This reveals the robustness of the root microbiota against the onset and perpetual flowering of A. alpina. Together with previous studies, this implies a model in which parts of the root microbiota modulate flowering time, whereas, after microbiota acquisition during vegetative growth, the established root-associated bacterial assemblage is structurally robust to perturbations caused by flowering and drastic changes in plant stature.

  10. Eddy-correlation measurements of benthic fluxes under complex flow conditions: Effects of coordinate transformations and averaging time scales

    DEFF Research Database (Denmark)

    Lorke, Andreas; McGinnis, Daniel F.; Maeck, Andreas

    2013-01-01

    hours of continuous eddy-correlation measurements of sediment oxygen fluxes in an impounded river, we demonstrate that rotation of measured current velocities into streamline coordinates can be a crucial and necessary step in data processing under complex flow conditions in non-flat environments......Eddy-correlation measurements of sediment oxygen uptake rates in aquatic systems are increasingly used to obtain areal-averaged fluxes with a high temporal resolution. Here we discuss the effects of coordinate rotation and averaging time scale for Reynolds decomposition on flux estimates. Using 119...... in the context of the theoretical concepts underlying eddy-correlation measurements and a set of recommendations for planning and analyses of flux measurements are derived....

  11. Method for Making Measurements of the Post-Combustion Residence Time in a Gas Turbine Engine

    Science.gov (United States)

    Miles, Jeffrey H. (Inventor)

    2017-01-01

    A method of measuring a residence time in a gas-turbine engine is disclosed that includes measuring a combustor pressure signal at a combustor entrance and a turbine exit pressure signal at a turbine exit. The method further includes computing a cross-spectrum function between the combustor pressure signal and the turbine exit pressure signal, calculating a slope of the cross-spectrum function, shifting the turbine exit pressure signal an amount corresponding to a time delay between the measurement of the combustor pressure signal and the turbine exit pressure signal, and recalculating the slope of the cross-spectrum function until the slope reaches zero.

  12. Long-time averaged dynamics of a Bose–Einstein condensate in a bichromatic optical lattice with external harmonic confinement

    Energy Technology Data Exchange (ETDEWEB)

    Sakhel, Asaad R., E-mail: asaad.sakhel@fet.edu.jo [Department of Physics and Basic Sciences, Faculty of Engineering Technology, Balqa Applied University, Amman 11134 (Jordan); Abdus-Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste (Italy)

    2016-07-15

    The dynamics of a Bose–Einstein condensate are examined numerically in the presence of a one-dimensional bichromatic optical lattice (BCOL) with external harmonic confinement in the strongly interacting regime. The condensate is excited by a focusing stirring red laser. Two realizations of the BCOL are considered, one with a rational and the other with an irrational ratio of the two constituting wave lengths. The system is simulated by the time-dependent Gross Pitaevskii equation that is solved using the Crank Nicolson method in real time. It is found that for a weak BCOL, the long-time averaged physical observables of the condensate respond only very weakly (or not at all) to changes in the secondary OL depth V{sub 1} showing that under these conditions the harmonic trap plays a dominant role in governing the dynamics. However, for a much larger strength of the BCOL, the response is stronger as it begins to compete with the external harmonic trap, such that the frequency of Bloch oscillations of the bosons rises with V{sub 1} yielding higher time-averages. Qualitatively there is no difference between the dynamics of the condensate resulting from the use of a rational or irrational ratio of the wavelengths since the external harmonic trap washes it out. It is further found that in the presence of an external harmonic trap, the BCOL acts in favor of superflow.

  13. Instantaneous and time-averaged flow fields of multiple vortices in the tip region of a ducted propulsor

    Energy Technology Data Exchange (ETDEWEB)

    Oweis, Ghanem F.; Ceccio, Steven L. [University of Michigan, Department of Mechanical Engineering, Ann Arbor, MI (United States)

    2005-05-01

    The instantaneous and time-averaged flow fields in the tip region of a ducted marine propulsor are examined. In this flow, a primary tip-leakage vortex interacts with a secondary, co-rotating trailing edge vortex and other co- and counter-rotating vorticity found in the blade wake. Planar particle imaging velocimetry (PIV) is used to examine the flow in a plane approximately perpendicular to the mean axis of the primary vortex. An identification procedure is used to characterize multiple regions of compact vorticity in the flow fields as series of Gaussian vortices. Significant differences are found between the vortex properties from the time-averaged flow fields and the average vortex properties identified in the instantaneous flow fields. Variability in the vortical flow field results from spatial wandering of the vortices, correlated fluctuations of the vortex strength and core size, and both correlated and uncorrelated fluctuations in the relative positions of the vortices. This variability leads to pseudo-turbulent velocity fluctuations. Corrections for some of this variability are performed on the instantaneous flow fields. The resulting processed flow fields reveal a significant increase in flow variability in a region relatively far downstream of the blade trailing edge, a phenomenon that is masked through the process of simple averaging. This increased flow variability is also accompanied by the inception of discrete vortex cavitation bubbles, which is an unexpected result, since the mean flow pressures in the region of inception are much higher than the vapor pressure of the liquid. This suggests that unresolved fine-scale vortex interactions and stretching may be occurring in the region of increased flow variability. (orig.)

  14. Instantaneous and time-averaged flow fields of multiple vortices in the tip region of a ducted propulsor

    Science.gov (United States)

    Oweis, Ghanem F.; Ceccio, Steven L.

    2005-05-01

    The instantaneous and time-averaged flow fields in the tip region of a ducted marine propulsor are examined. In this flow, a primary tip-leakage vortex interacts with a secondary, co-rotating trailing edge vortex and other co- and counter-rotating vorticity found in the blade wake. Planar particle imaging velocimetry (PIV) is used to examine the flow in a plane approximately perpendicular to the mean axis of the primary vortex. An identification procedure is used to characterize multiple regions of compact vorticity in the flow fields as series of Gaussian vortices. Significant differences are found between the vortex properties from the time-averaged flow fields and the average vortex properties identified in the instantaneous flow fields. Variability in the vortical flow field results from spatial wandering of the vortices, correlated fluctuations of the vortex strength and core size, and both correlated and uncorrelated fluctuations in the relative positions of the vortices. This variability leads to pseudo-turbulent velocity fluctuations. Corrections for some of this variability are performed on the instantaneous flow fields. The resulting processed flow fields reveal a significant increase in flow variability in a region relatively far downstream of the blade trailing edge, a phenomenon that is masked through the process of simple averaging. This increased flow variability is also accompanied by the inception of discrete vortex cavitation bubbles, which is an unexpected result, since the mean flow pressures in the region of inception are much higher than the vapor pressure of the liquid. This suggests that unresolved fine-scale vortex interactions and stretching may be occurring in the region of increased flow variability.

  15. Baseline and time-averaged fluid removal affect technique survival in peritoneal dialysis in a non-linear fashion.

    Science.gov (United States)

    Wiggins, Kathryn J; Rumpsfeld, Markus; Hawley, Carmel M; O'Shea, Amanda; Isbel, Nicole M; Campbell, Scott B; Johnson, David W

    2007-06-01

    The longevity of peritoneal dialysis (PD) is limited by technique failure and patient mortality. The authors assessed the influence of baseline and time-averaged fluid removal on patient, technique and death-censored technique survival. Peritoneal and total fluid removal was measured 1 month after commencing PD, then 6 monthly, in 225 incident patients (mean age 55.3+/-15.8 years, 52% male). A Cox proportional hazards model regression analysis was performed to identify variables independently predictive of technique and patient survival. Seventy (31.9%) patients were transferred to haemodialysis and 39 (17.63%) died. Technique survival was greatest in the middle tertile of baseline total fluid removal (mean survival time 3.5 vs 2.5 and 2.2 years for the lower and upper tertiles, respectively, log rank 6.5, P=0.039). The middle tertile of both baseline and time-averaged total fluid removal were significant predictors of PD survival (adjusted hazard ratio (HR) 0.476, 95% CI 0.286-0.795, P=0.005 relative to the upper tertile and HR 0.573, 95% CI 0.350-0.939, P=0.027 for baseline and time-averaged, respectively). Other significant variables on multivariate analysis were body mass index (HR 1.044 per kg/m2, 95% CI 1.005-1.084, P=0.028), creatinine (HR 0.999 per micromol, 95% CI 0.998-1.000, P=0.048) and residual Kt/V (HR 0.418, 95% CI 0.233-0.747, P=0.003). Patient survival was not affected by fluid removal. Patients with moderate total fluid removal both at baseline and throughout their PD career have improved technique survival. Attention should be paid to optimizing total fluid removal.

  16. Derivation of the Multi-fluid Model using the Time-Volume Averaging Method in Porous Body

    International Nuclear Information System (INIS)

    Lee, Sang Yong; Park, Chan Eok; Kim, Eun Kee

    2010-01-01

    The local instantaneous balance equation reads as, ∂/∂t(ρ k ψ k )+∇·(ρ k ψ k u k )=-∇·J k +ρ k ψ k (1) where ρ k ,ψ k ,u k ,J k and φ k are the density, property of extensive characteristics, velocity, flux and source of k-phase, respectively. Nomenclatures for other variables are found in. Table-1 shows the field variables. e k ,q k ,ρ k ,γ k ,g k ,q k ,M k ,E k are internal energy, heat flux, pressure, vaporization, gravity and internal heat rate, interfacial momentum and energy sources respectively. is the stress tensor and is decomposed into pressure and shear. The time averaged balance equation for any property ψ k of k-phase can be presented as, ∂/∂t(ρ k ψ k )+∇·(ρ k ψ k U k )=-∇·J k +ρ k φ k +I k . I k ≡-I/ΔtΣ j {I/u ni [(ρ k ψ k )n k ·(u k -u i )-(n k ·J k )]} (2) where the bar over a quantity indicates the time-averaging operation.is the surface normal vector in this paper. Considering the time-fluctuating terms, the time-averaged balance equation can be represented by using weighted mean variables as, (J k T : turbulent effectsTkJ): ∂/∂t(ρ k ψ k )+∇·(ρ k ψ k u k )=-∇·(J k +J k T )+ρ k φ k +I k

  17. Iterated real-time path integral evaluation using a distributed approximating functional propagator and average-case complexity integration

    International Nuclear Information System (INIS)

    Kouri, D.J.; Huang, Y.; Hoffman, D.K.

    1995-01-01

    The distributed approximating functional-path integral is formulated as an iterated sequence of d-dimensional integrals, where d is the intrinsic number of degrees of freedom for the system under consideration. This is made practical for larger values of d by evaluating these integrals using average-case complexity integration techniques, based on deterministic ''low discrepancy sequences,'' as opposed to products of one-dimensional quadratures or basis functions. The integration converges as (logP) d-1 /P, where P is the number of sample points used, and the dimensionality of the integral does not increase with the number of time slices required

  18. Mucoadhesive nano-sized supramolecular assemblies for improved pre-corneal drug residence time.

    Science.gov (United States)

    Fabiano, Angela; Chetoni, Patrizia; Zambito, Ylenia

    2015-01-01

    Mucoadhesive nanoparticles were compared with non-aggregated constituent polymers for effect on pre-corneal residence of dexamethasone phosphate (DP) or met-enkephalin (ME), administered by eye-drops to rabbits. Deepening the knowledge of ophthalmic nanoparticulate systems in terms of ability to prolong pre-corneal residence. Medicated nanoparticles resulted from gelation of quaternary ammonium-chitosan conjugate or its thiolated derivative with hyaluronan in the presence of drug. Particles were analyzed by light scattering. Dialysis removed non-encapsulated drug, dynamic dialysis measured drug-polymer interactions, and lyophilization-stabilized product. Dispersions were regenerated from lyophilized products. Also solutions of non-thiolated or thiolated chitosan derivative were administered. Mean drug residence time (MRT) in tears was determined by collecting samples from lower marginal tear strip of albino rabbits using capillaries. Nanoparticle size of regenerated dispersions was 400-430 nm (DP-systems), 360-370 nm (ME-systems); the drug content was 2.5 mg/mL (DP) or 0.3 mg/mL (ME). The MRT for DP nanoparticles from non-thiolated derivative was higher than that for non-aggregated polymer, due to stronger concurrent interactions of positively charged nanoparticles with ocular surface and drug. Thiolated polymer nanoparticles and non-aggregated parent polymer, both interacting weakly with DP, showed similar MRT values. The MRT of ME could only be enhanced by protecting drug from enzymatic hydrolysis. This was done by nanoparticle systems, whereas non-aggregated polymers were ineffective. Developing a nanoparticle system rather than a solution of mucoadhesive polymer, for prolonging pre-corneal residence, is convenient, provided nanoparticles interact strongly with both ocular surface and drug, or protect drug from metabolic degradation.

  19. Fractional-time random walk subdiffusion and anomalous transport with finite mean residence times: faster, not slower.

    Science.gov (United States)

    Goychuk, Igor

    2012-08-01

    Continuous time random walk (CTRW) subdiffusion along with the associated fractional Fokker-Planck equation (FFPE) is traditionally based on the premise of random clock with divergent mean period. This work considers an alternative CTRW and FFPE description which is featured by finite mean residence times (MRTs) in any spatial domain of finite size. Transient subdiffusive transport can occur on a very large time scale τ(c) which can greatly exceed mean residence time in any trap, τ(c) >(τ), and even not being related to it. Asymptotically, on a macroscale transport becomes normal for t > τ(c). However, mesoscopic transport is anomalous. Differently from viscoelastic subdiffusion no long-range anticorrelations among position increments are required. Moreover, our study makes it obvious that the transient subdiffusion and transport are faster than one expects from their normal asymptotic limit on a macroscale. This observation has profound implications for anomalous mesoscopic transport processes in biological cells because the macroscopic viscosity of cytoplasm is finite.

  20. Flow and Residence Times of Dynamic River Bank Storage and Sinuosity-Driven Hyporheic Exchange

    Science.gov (United States)

    Gomez-Velez, J. D.; Wilson, J. L.; Cardenas, M. B.; Harvey, J. W.

    2017-10-01

    Hydrologic exchange fluxes (HEFs) vary significantly along river corridors due to spatiotemporal changes in discharge and geomorphology. This variability results in the emergence of biogeochemical hot-spots and hot-moments that ultimately control solute and energy transport and ecosystem services from the local to the watershed scales. In this work, we use a reduced-order model to gain mechanistic understanding of river bank storage and sinuosity-driven hyporheic exchange induced by transient river discharge. This is the first time that a systematic analysis of both processes is presented and serves as an initial step to propose parsimonious, physics-based models for better predictions of water quality at the large watershed scale. The effects of channel sinuosity, alluvial valley slope, hydraulic conductivity, and river stage forcing intensity and duration are encapsulated in dimensionless variables that can be easily estimated or constrained. We find that the importance of perturbations in the hyporheic zone's flux, residence times, and geometry is mainly explained by two-dimensionless variables representing the ratio of the hydraulic time constant of the aquifer and the duration of the event (Γd) and the importance of the ambient groundwater flow (Δh∗). Our model additionally shows that even systems with small sensitivity, resulting in small changes in the hyporheic zone extent, are characterized by highly variable exchange fluxes and residence times. These findings highlight the importance of including dynamic changes in hyporheic zones for typical HEF models such as the transient storage model.

  1. Residence time and movements of postbreeding shorebirds on the northern coast of Alaska

    Science.gov (United States)

    Taylor, Audrey R.; Lanctot, Richard B.; Powell, Abby N.; Kendall, Steven J.; Nigro, Debora A.

    2011-01-01

    Relatively little is known about shorebird movements across the coast of northern Alaska, yet postbreeding shorebirds use this coastline extensively prior to fall migration. We deployed 346 radio transmitters on 153 breeding and 193 postbreeding shorebirds of five species from 2005 to 2007.We examined two hypotheses regarding postbreeding shorebirds' movements: (1) whether such movements reflect ultimate routes of southbound migration and (2) whether migration strategy (length of flights) or timing of molt in relation to migration (molt occurring in breeding or winter range) are more influential in determining postbreeding shorebirds' behavior. Semipalmated Sandpipers (Calidris pusilla) moved east, consistent with the direction of their ultimate migration, but patterns of other species' movements did not reflect ultimate migration direction. Timing of postnuptial molt appeared to have more influence over residence time and movements than did migration strategy. Postcapture residence time for the Semipalmated Sandpiper was less than for the Western Sandpiper (C. mauri) and significantly less than for Dunlin (C. alpina), and the Semipalmated Sandpiper's movements between were quicker and more frequent than those of the Dunlin. We expected to see the opposite patterns if migration strategy were more influential. Our data shed light on how different shorebird species use the northern Alaska coast after breeding: most species are likely to be stopping over at postbreeding areas, whereas the Dunlin and some Western Sandpipers may be staging. We suggest the coast of northern Alaska be viewed as an interconnected network of postbreeding sites that serve multiple populations of breeding shorebirds.

  2. State Averages

    Data.gov (United States)

    U.S. Department of Health & Human Services — A list of a variety of averages for each state or territory as well as the national average, including each quality measure, staffing, fine amount and number of...

  3. Estimation of residence times of coastal basins in the Laxemar- Simpevarp area between 3000 BC and 9000 AD

    Energy Technology Data Exchange (ETDEWEB)

    Engqvist, Anders (AandI Engqvist Konsult HB, Vaxholm (Sweden))

    2010-09-15

    The assignment has consisted of computation of the morpho- and bathymetry of the coastal area of Laxemar-Simpevarp for the time period 3000 BC through 9000 AD, in order to estimate the residence times as yearly means of volume-averaged specific age (Average Age, AvA) for water in coastal basins. These basins have been selected as belonging to earlier defined biosphere objects, containing anticipated exit points from possible radionuclides leaking from a hypothetical underground repository for spent nuclear fuel. This endeavor starts with partitioning of the coast into appropriate sub-basins interconnected by straits in an as objective manner as possible. This has been performed in cooperation with Umeaa Univ. followed by the transformation of these hypsographical data to a form that can serve as input data to the employed numerical CouBa-model. This model has been developed to simulate the water exchange of straits between densimetrically stably stratified basins with a free sea level including advection and mixing of water-borne conservative scalar properties, e.g. salinity, heat and specific age. The forcing of the model consists of run-off, wind-induced stress, thermal surface dynamics (heating/cooling) and density fluctuations at the open boundary toward the coastal zone, relative by which the specific water age is calculated For these ambient forcing factors there do not exist sufficiently precise climate data other than for contemporary times. For all other time periods the measured and/or model-computed forcing data regarding 2004 have been used. Estimated AvA-values for the different time periods are thus an expression of sub-basin configuration and hypsographical differences. An overriding directive has been to rather overestimate than underestimate the residence times, as to avoid underestimation of the subsequent dose calculations. The results of these AvA computations, presented as volume averages of yearly means of the sixteen biosphere object

  4. Spatial distribution of triazine residues in a shallow alluvial aquifer linked to groundwater residence time.

    Science.gov (United States)

    Sassine, Lara; Le Gal La Salle, Corinne; Khaska, Mahmoud; Verdoux, Patrick; Meffre, Patrick; Benfodda, Zohra; Roig, Benoît

    2017-03-01

    At present, some triazine herbicides occurrence in European groundwater, 13 years after their use ban in the European Union, remains of great concern and raises the question of their persistence in groundwater systems due to several factors such as storage and remobilization from soil and unsaturated zone, limited or absence of degradation, sorption in saturated zones, or to continuing illegal applications. In order to address this problem and to determine triazine distribution in the saturated zone, their occurrence is investigated in the light of the aquifer hydrodynamic on the basis of a geochemical approach using groundwater dating tracers ( 3 H/ 3 He). In this study, atrazine, simazine, terbuthylazine, deethylatrazine, deisopropylatrazine, and deethylterbuthylazine are measured in 66 samples collected between 2011 and 2013 from 21 sampling points, on the Vistrenque shallow alluvial aquifer (southern France), covered by a major agricultural land use. The frequencies of quantification range from 100 to 56 % for simazine and atrazine, respectively (LQ = 1 ng L -1 ). Total triazine concentrations vary between 15 and 350 ng L -1 and show three different patterns with depth below the water table: (1) low concentrations independent of depth but related to water origin, (2) an increase in concentrations with depth in the aquifer related to groundwater residence time and triazine use prior to their ban, and (3) relatively high concentrations at low depths in the saturated zone more likely related to a slow desorption of these compounds from the soil and unsaturated zone. The triazine attenuation rate varies between 0.3 for waters influenced by surface water infiltration and 4.8 for water showing longer residence times in the aquifer, suggesting an increase in these rates with water residence time in the saturated zone. Increasing triazine concentrations with depth is consistent with a significant decrease in the use of these pesticides for the last 10 years on

  5. Effect of a planar interface on time-averaged locomotion of a spherical squirmer in a viscoelastic fluid

    Science.gov (United States)

    Yazdi, Shahrzad; Borhan, Ali

    2017-09-01

    We examine the time-averaged locomotion of a spherical squirmer with reciprocal surface motion near a planar interface in a viscoelastic fluid. The system dynamics is investigated through a phase portrait in the swimming orientation and distance from the interface for three types of swimming gaits, namely, pullers, pushers, and neutral swimmers. To examine the kinematics of locomotion near different types of boundaries, the ratio of viscosities of the two phases adjacent to the planar interface is varied. Our results show that the near-wall attraction layer previously reported for a two-dimensional squirmer does not exist for spherical pullers and pushers. However, the presence of a stable node can attract the swimmer to the vicinity of the interface, depending on the initial swimming direction. In contrast to a two-dimensional neutral squirmer that always swims towards a no-slip boundary, a spherical neutral swimmer moves away from the interface, but the direction of time-averaged rotational velocity favors eventual entrapment of the squirmer at a stable node. We show that the position of the stable node depends on the boundary type and is furthest from the interface for a no-slip boundary.

  6. Surgery resident learning styles and academic achievement.

    Science.gov (United States)

    Contessa, Jack; Ciardiello, Kenneth A; Perlman, Stacie

    2005-01-01

    To determine if surgical residents share a preferred learning style as measured by Kolb's Learning Style Inventory (LSI) and if a relationship exists between resident learning style and achievement as measured by a standardized examination (AME). Also, core faculty learning styles were assessed to determine if faculty and residents share a preferred learning style. Kolb's LSI, Version 3, was administered to 16 surgical residents and the residency program's core faculty of 6 attending physicians. To measure academic achievement, the American Medical Education (AME) examination was administered to residents. The Hospital of Saint Raphael, General Surgery Residency Program, New Haven, Connecticut. Both instruments were administered to residents during protected core curriculum time. Core faculty were administered the LSI on an individual basis. Surgical residents of the Hospital of Saint Raphael's General Surgery Residency Program and 6 core faculty members Analysis of resident learning style preference revealed Converging as the most commonly occurring style for residents (7) followed by Accommodating (5), Assimilating (3), and Diverging (1). The predominant learning style for core faculty was also Converging (4) with 2 Divergers. The average score for the Convergers on the AME was 62.6 compared with 42 for the next most frequently occurring learning style, Accommodators. In this surgical residency program, a preferred learning style for residents seems to exist (Converging), which confirms what previous studies have found. Additionally, residents with this learning style attained a higher average achievement score as measured by the AME. Also, core faculty share the same preferential learning style as this subset of residents.

  7. The muddle of ages, turnover, transit, and residence times in the carbon cycle.

    Science.gov (United States)

    Sierra, Carlos A; Müller, Markus; Metzler, Holger; Manzoni, Stefano; Trumbore, Susan E

    2017-05-01

    Comparisons among ecosystem models or ecosystem dynamics along environmental gradients commonly rely on metrics that integrate different processes into a useful diagnostic. Terms such as age, turnover, residence, and transit times are often used for this purpose; however, these terms are variably defined in the literature and in many cases, calculations ignore assumptions implicit in their formulas. The aim of this opinion piece was i) to make evident these discrepancies and the incorrect use of formulas, ii) highlight recent results that simplify calculations and may help to avoid confusion, and iii) propose the adoption of simple and less ambiguous terms. © 2016 John Wiley & Sons Ltd.

  8. Trait differences between naturalized and invasive plant species independent of residence time and phylogeny

    Science.gov (United States)

    Gallagher, R V; Randall, R P; Leishman, M R

    2015-01-01

    The ability to predict which alien plants will transition from naturalized to invasive prior to their introduction to novel regions is a key goal for conservation and has the potential to increase the efficacy of weed risk assessment (WRA). However, multiple factors contribute to plant invasion success (e.g., functional traits, range characteristics, residence time, phylogeny), and they all must be taken into account simultaneously in order to identify meaningful correlates of invasion success. We compiled 146 pairs of phylogenetically paired (congeneric) naturalized and invasive plant species in Australia with similar minimum residence times (i.e., time since introduction in years). These pairs were used to test for differences in 5 functional traits (flowering duration, leaf size, maximum height, specific leaf area [SLA], seed mass) and 3 characteristics of species’ native ranges (biome occupancy, mean annual temperature, and rainfall breadth) between naturalized and invasive species. Invasive species, on average, had larger SLA, longer flowering periods, and were taller than their congeneric naturalized relatives. Invaders also exhibited greater tolerance for different environmental conditions in the native range, where they occupied more biomes and a wider breadth of rainfall and temperature conditions than naturalized congeners. However, neither seed mass nor leaf size differed between pairs of naturalized and invasive species. A key finding was the role of SLA in distinguishing between naturalized and invasive pairs. Species with high SLA values were typically associated with faster growth rates, more rapid turnover of leaf material, and shorter lifespans than those species with low SLA. This suite of characteristics may contribute to the ability of a species to transition from naturalized to invasive across a wide range of environmental contexts and disturbance regimes. Our findings will help in the refinement of WRA protocols, and we advocate the

  9. Using just-in-time teaching and peer instruction in a residency program's core curriculum: enhancing satisfaction, engagement, and retention.

    Science.gov (United States)

    Schuller, Mary C; DaRosa, Debra A; Crandall, Marie L

    2015-03-01

    To assess use of the combined just-in-time teaching (JiTT) and peer instruction (PI) instructional strategy in a residency program's core curriculum. In 2010-2011, JiTT/PI was piloted in 31 core curriculum sessions taught by 22 faculty in the Northwestern University Feinberg School of Medicine's general surgery residency program. JiTT/PI required preliminary and categorical residents (n=31) to complete Web-based study questions before weekly specialty topic sessions. Responses were examined by faculty members "just in time" to tailor session content to residents' learning needs. In the sessions, residents answered multiple-choice questions (MCQs) using clickers and engaged in PI. Participants completed surveys assessing their perceptions of JiTT/PI. Videos were coded to assess resident engagement time in JiTT/PI sessions versus prior lecture-based sessions. Responses to topic session MCQs repeated in review sessions were evaluated to study retention. More than 70% of resident survey respondents indicated that JiTT/PI aided in the learning of key points. At least 90% of faculty survey respondents reported positive perceptions of aspects of the JiTT/PI strategy. Resident engagement time for JiTT/PI sessions was significantly greater than for prior lecture-based sessions (z=-2.4, P=.016). Significantly more review session MCQ responses were correct for residents who had attended corresponding JiTT/PI sessions than for residents who had not (chi-square=13.7; df=1; P<.001). JiTT/PI increased learner participation, learner retention, and the amount of learner-centered time. JiTT/PI represents an effective approach for meaningful and active learning in core curriculum sessions.

  10. Reynolds number dependence of an upper bound for the long-time-averaged buoyancy flux in plane stratified Couette flow

    Science.gov (United States)

    Caulfield, C. P.; Tang, W.; Plasting, S. C.

    2004-01-01

    We derive an improved rigorous upper bound for the long-time-averaged vertical buoyancy flux for stably stratified Couette flow; i.e. the flow of a Boussinesq fluid (with reference density rho_0, kinematic viscosity nu, and thermal diffusivity kappa) confined between two parallel horizontal plates separated by a distance d, which are driven at a constant relative velocity uDelta U, and are maintained at a constant (statically stable) temperature difference leading to a constant density difference uDelta rho. We construct the bound by means of a numerical solution to the ‘background method’ variation problem as formulated by Constantin and Doering using a one-dimensional uni-directional background. The upper bound so constructed is the best possible bound with the imposed constraints for streamwise independent mean flows that are statistically steady, and is calculated up to asymptotically large Reynolds numbers. We find that the associated (dimensional) upper bound {cal B}(*_{scriptsize) max} on the long-time-averaged and volume averaged buoyancy flux {cal B}(*:=lim_{t) -> infty} (1/t) int(t_0) g/rho_{0} dskew2tilde{t} (where u_3 is the vertical velocity, g is the acceleration due to gravity, and angled brackets denote volume averaging) does not depend on either the bulk Richardson number J=guDelta rho d/(rho_0 uDelta U(2)) of the flow, or the Prandtl number sigma=nu/kappa of the fluid. We show that {cal B}(*_{scriptsize) max} has the same inertial characteristic scaling as the (dimensional) mechanical energy dissipation rate {cal E}(*_B) , and {cal B}(*_{scriptsize) max}=0.001267uDelta U(3/d) as Re->infty. The associated flow structure exhibits velocity boundary layers embedded within density boundary layers, with local gradient Richardson numbers Ri =O(sigma/Re)≪ 1 in the vicinity of the horizontal plates. There is a correspondence between the predicted flow structure and the flow structure at a lower Reynolds number associated with the upper bound on the

  11. Comparison of Techniques to Estimate Ammonia Emissions at Cattle Feedlots Using Time-Averaged and Instantaneous Concentration Measurements

    Science.gov (United States)

    Shonkwiler, K. B.; Ham, J. M.; Williams, C. M.

    2013-12-01

    Ammonia (NH3) that volatilizes from confined animal feeding operations (CAFOs) can form aerosols that travel long distances where such aerosols can deposit in sensitive regions, potentially causing harm to local ecosystems. However, quantifying the emissions of ammonia from CAFOs through direct measurement is very difficult and costly to perform. A system was therefore developed at Colorado State University for conditionally sampling NH3 concentrations based on weather parameters measured using inexpensive equipment. These systems use passive diffusive cartridges (Radiello, Sigma-Aldrich, St. Louis, MO, USA) that provide time-averaged concentrations representative of a two-week deployment period. The samplers are exposed by a robotic mechanism so they are only deployed when wind is from the direction of the CAFO at 1.4 m/s or greater. These concentration data, along with other weather variables measured during each sampler deployment period, can then be used in a simple inverse model (FIDES, UMR Environnement et Grandes Cultures, Thiverval-Grignon, France) to estimate emissions. There are not yet any direct comparisons of the modeled emissions derived from time-averaged concentration data to modeled emissions from more sophisticated backward Lagrangian stochastic (bLs) techniques that utilize instantaneous measurements of NH3 concentration. In the summer and autumn of 2013, a suite of robotic passive sampler systems were deployed at a 25,000-head cattle feedlot at the same time as an open-path infrared (IR) diode laser (GasFinder2, Boreal Laser Inc., Edmonton, Alberta, Canada) which continuously measured ammonia concentrations instantaneously over a 225-m path. This particular laser is utilized in agricultural settings, and in combination with a bLs model (WindTrax, Thunder Beach Scientific, Inc., Halifax, Nova Scotia, Canada), has become a common method for estimating NH3 emissions from a variety of agricultural and industrial operations. This study will first

  12. The Status of Social and Leisure Time Activities in the Elderly Residing In Iran and Sweden

    Directory of Open Access Journals (Sweden)

    Seyed Bagher Madah

    2008-07-01

    Full Text Available Objectives: Among social determinants of health, culture and ethnicity play a key role in defining the needs of different population groups. The aim of this study was to consider and compare the social and leisure time activities of the three elderly groups: Iranian residing in Iran, Iranian residing in Sweden and Swedish residing in Sweden. Methods & Materials: Via the cross-sectional design, 825 Iranian elderly who were living in Tehran compared with 305 Swedish elderly and 101 Iranian elderly living in Stockholm on social relations, group activities and leisure time activities. Only, elderly who could communicate properly entered the study. A structured questionnaire designed by the Iranian and Swedish Research Group on the" Assessment of Social Health Status and Needs" implemented for the subjects. Estimation method and logistic regression used to analyze the gathered data. Results: Subjects of all 3 groups were in the age range of 60-77 years old and mostly were married. Results showed despite very common characteristics, there are, also, many differences which can be explained by cultural and environmental factors. Rapid urbanization, limited resources and unawareness of or disregard for healthy life style resulted in lower levels of satisfaction with social and leisure life in the Iranian elderly. On the other hand, level of activities related to the spiritual dimension of health were more in Iranians than Swedish and the difference was significant (P=0.000, whereas the reverse was true for the group activities (P=0.000. Poor attitude toward physical activity and exercise in Iranian elderly, especially women, with consequent hazards for health, needs special consideration on behalf of the health planners and providers. Conclusion: Needs assessment with trance- cultural approach, especially on social determinants of the health of elderly is a necessity. Using valid and reliable instruments, designed to overcome the cultural barriers would

  13. Keeping up with the times: revising the dermatology residency curriculum in the era of molecular diagnostics and personalized medicine.

    Science.gov (United States)

    LaChance, Avery; Murphy, Michael J

    2014-11-01

    The clinical use of molecular diagnostics, genomics, and personalized medicine is increasing and improving rapidly over time. However, medical education incorporating the practical application of these techniques is lagging behind. Although instruction in these areas should be expanded upon and improved at all levels of training, residency provides a concentrated period of time in which to hone in on skills that are practically applicable to a trainee's specialty of choice. Although residencies in some fields, such as pathology, have begun to incorporate practical molecular diagnostics training, this area remains a relative gap in dermatology residency programs. Herein, we advocate for the incorporation of training in molecular diagnostics and personalized medicine into dermatology residency programs and propose a basic curriculum template for how to begin approaching these topics. By incorporating molecular diagnostics into dermatology residency training, dermatologists have the opportunity to lead the way and actively shape the specialty's transition into the era of personalized medicine. © 2014 The International Society of Dermatology.

  14. Macrotextured spoked surfaces reduce the residence time of a bouncing Leidenfrost drop

    Science.gov (United States)

    Patterson, Colin J.; Shiri, Samira; Bird, James C.

    2017-02-01

    Liquid drops can bounce when they impact non-wetting surfaces. Recently, studies have demonstrated that the time that the bouncing drop contacts a superhydrophobic surface can be reduced by incorporating ridged macrotextures on the surface. Yet the existing models aimed at explaining this phenomenon offer incompatible predictions of the contact time when a drop impacts multiple intersecting macrotextures, or spokes. Furthermore, it is unclear whether the effects of the macrotexture on the drop hydrodynamics extend to non-wetting surfaces in which direct contact is avoided by a thin vapor layer. Here we demonstrate that the phenomenon observed for macrotextured, superhydrophobic surfaces extends to macrotextured, wettable surfaces above the Leidenfrost temperature. We show that the number of droplets and overall residence time both depend on the number of intersecting spokes. Finally, we compare and contrast our results with mechanistic models to rationalize various elements of the phenomenon.

  15. Fluid trajectory evaluation based on an ensemble-averaged cross-correlation in time-resolved PIV

    Science.gov (United States)

    Jeon, Young Jin; Chatellier, Ludovic; David, Laurent

    2014-07-01

    A novel multi-frame particle image velocimetry (PIV) method, able to evaluate a fluid trajectory by means of an ensemble-averaged cross-correlation, is introduced. The method integrates the advantages of the state-of-art time-resolved PIV (TR-PIV) methods to further enhance both robustness and dynamic range. The fluid trajectory follows a polynomial model with a prescribed order. A set of polynomial coefficients, which maximizes the ensemble-averaged cross-correlation value across the frames, is regarded as the most appropriate solution. To achieve a convergence of the trajectory in terms of polynomial coefficients, an ensemble-averaged cross-correlation map is constructed by sampling cross-correlation values near the predictor trajectory with respect to an imposed change of each polynomial coefficient. A relation between the given change and corresponding cross-correlation maps, which could be calculated from the ordinary cross-correlation, is derived. A disagreement between computational domain and corresponding physical domain is compensated by introducing the Jacobian matrix based on the image deformation scheme in accordance with the trajectory. An increased cost of the convergence calculation, associated with the nonlinearity of the fluid trajectory, is moderated by means of a V-cycle iteration. To validate enhancements of the present method, quantitative comparisons with the state-of-arts TR-PIV methods, e.g., the adaptive temporal interval, the multi-frame pyramid correlation and the fluid trajectory correlation, were carried out by using synthetically generated particle image sequences. The performances of the tested methods are discussed in algorithmic terms. A high-rate TR-PIV experiment of a flow over an airfoil demonstrates the effectiveness of the present method. It is shown that the present method is capable of reducing random errors in both velocity and material acceleration while suppressing spurious temporal fluctuations due to measurement noise.

  16. Walking, running, and resting under time, distance, and average speed constraints: optimality of walk–run–rest mixtures

    Science.gov (United States)

    Long, Leroy L.; Srinivasan, Manoj

    2013-01-01

    On a treadmill, humans switch from walking to running beyond a characteristic transition speed. Here, we study human choice between walking and running in a more ecological (non-treadmill) setting. We asked subjects to travel a given distance overground in a given allowed time duration. During this task, the subjects carried, and could look at, a stopwatch that counted down to zero. As expected, if the total time available were large, humans walk the whole distance. If the time available were small, humans mostly run. For an intermediate total time, humans often use a mixture of walking at a slow speed and running at a higher speed. With analytical and computational optimization, we show that using a walk–run mixture at intermediate speeds and a walk–rest mixture at the lowest average speeds is predicted by metabolic energy minimization, even with costs for transients—a consequence of non-convex energy curves. Thus, sometimes, steady locomotion may not be energy optimal, and not preferred, even in the absence of fatigue. Assuming similar non-convex energy curves, we conjecture that similar walk–run mixtures may be energetically beneficial to children following a parent and animals on long leashes. Humans and other animals might also benefit energetically from alternating between moving forward and standing still on a slow and sufficiently long treadmill. PMID:23365192

  17. Walking, running, and resting under time, distance, and average speed constraints: optimality of walk-run-rest mixtures.

    Science.gov (United States)

    Long, Leroy L; Srinivasan, Manoj

    2013-04-06

    On a treadmill, humans switch from walking to running beyond a characteristic transition speed. Here, we study human choice between walking and running in a more ecological (non-treadmill) setting. We asked subjects to travel a given distance overground in a given allowed time duration. During this task, the subjects carried, and could look at, a stopwatch that counted down to zero. As expected, if the total time available were large, humans walk the whole distance. If the time available were small, humans mostly run. For an intermediate total time, humans often use a mixture of walking at a slow speed and running at a higher speed. With analytical and computational optimization, we show that using a walk-run mixture at intermediate speeds and a walk-rest mixture at the lowest average speeds is predicted by metabolic energy minimization, even with costs for transients-a consequence of non-convex energy curves. Thus, sometimes, steady locomotion may not be energy optimal, and not preferred, even in the absence of fatigue. Assuming similar non-convex energy curves, we conjecture that similar walk-run mixtures may be energetically beneficial to children following a parent and animals on long leashes. Humans and other animals might also benefit energetically from alternating between moving forward and standing still on a slow and sufficiently long treadmill.

  18. Determination of the hydraulic residence time of trickling filters using radiotracer experiments

    International Nuclear Information System (INIS)

    Debien, Bruno R.; Ferreira, Ladislau M.; Barreto, Alberto A.; Pinto, Amenonia M.F.

    2013-01-01

    Trickling filters (TF) are bioreactors fulfilled with inert materials working as support for biofilm development, and have been used in a large scale in wastewater treatment for organic matter, ammonia nitrogen and nitrate removal. TF's can be widely used in Brazil, especially because of its simplicity and operational low cost. The efficiency of pollutants removal processes depends on the water flow dynamics inside the reactor. For this reason, in the present work the mean residence time of two TF's containing different support materials were determined by means of tracer testes. The radioisotope 82Br - a gamma radiation emitter, produced from soluble potassium bromide irradiated in the TRIGA reactor at the Centre for the Development of Nuclear Energy (CDTN) - was used as a pseudo-conservative tracer for the comparative study of aqueous phase flow dynamics in both TF's. Mean residence time for the first TF (containing a single support material) was 0,3 hours, much smaller than the value obtained for the second TF (containing two alternated support materials), around 2 hours. These results were already expected, once the alternated material is denser than the single one, and are very important for numerical modeling studies aiming to determine the kinetic constant for removal of the pollutants cited above. (author)

  19. A non-discrete method for computation of residence time in fluid mechanics simulations.

    Science.gov (United States)

    Esmaily-Moghadam, Mahdi; Hsia, Tain-Yen; Marsden, Alison L

    2013-11-01

    Cardiovascular simulations provide a promising means to predict risk of thrombosis in grafts, devices, and surgical anatomies in adult and pediatric patients. Although the pathways for platelet activation and clot formation are not yet fully understood, recent findings suggest that thrombosis risk is increased in regions of flow recirculation and high residence time (RT). Current approaches for calculating RT are typically based on releasing a finite number of Lagrangian particles into the flow field and calculating RT by tracking their positions. However, special care must be taken to achieve temporal and spatial convergence, often requiring repeated simulations. In this work, we introduce a non-discrete method in which RT is calculated in an Eulerian framework using the advection-diffusion equation. We first present the formulation for calculating residence time in a given region of interest using two alternate definitions. The physical significance and sensitivity of the two measures of RT are discussed and their mathematical relation is established. An extension to a point-wise value is also presented. The methods presented here are then applied in a 2D cavity and two representative clinical scenarios, involving shunt placement for single ventricle heart defects and Kawasaki disease. In the second case study, we explored the relationship between RT and wall shear stress, a parameter of particular importance in cardiovascular disease.

  20. Determination of flow patterns in industrial gold leaching tank by radiotracer residence time distribution measurement

    International Nuclear Information System (INIS)

    Stegowski, Z.; Furman, L.; Dagadu, Ch.P.K.; Akaho, E.H.K.; Danso, K.A.; Mumuni, I.I.; Adu, P.S; Amoah, Ch.

    2010-01-01

    The carbon-in-leach (CIL) process is one the most efficient methods of gold recovery from gold bearing ores. The efficiency of the leaching process greatly depends on the flow structure created by mechanical agitation (in some cases air agitation) in the leaching tanks. Residence time distribution (RTD) measurement was conducted in the CIL section of a gold processing plant in order to determine the flow structure in the first tank using the 131 I radioactive tracer. The shape of the experimental data revealed that the flow behaviour in the tank was close to an ideal mixer. Modelling of the experimental data, however, revealed that the tank was not behaving as a single perfect mixer, but consisted of two mixing zones. The flow structure in the tank was best described by the '' perfect mixers with exchange '' model consisting of two mixing zones. The model allowed the determination of flow parameters including the mean residence time, flow rate and volumes of the mixing zones. (authors)

  1. Tritium activity concentrations and residence times of groundwater collected in Rokkasho, Japan.

    Science.gov (United States)

    Hasegawa, Hidenao; Ueda, Shinji; Akata, Naofumi; Kakiuchi, Hideki; Hisamatsu, Shun'ichi

    2015-11-01

    Tritium ((3)H) concentrations were measured in groundwater samples from four surface wells (4-10 m deep), four shallow wells (24-26.5 m deep) and a 150-m-deep well in the Futamata River catchment area, which is adjacent to the large-scale commercial spent nuclear fuel reprocessing plant in Rokkasho, Japan. The (3)H concentrations in most of the surface- and shallow-well samples (<0.03-0.57 Bq l(-1)) were similar to those in precipitation (annual mean: 0.31-0.79 Bq l(-1)), suggesting that the residence time of the water in those wells was 0-15 y. The (3)H concentrations in the samples from a 26-m-deep well and the 150-m-deep well were lower than those in the other wells, indicating that groundwater with a long residence time exists in deep aquifers and the estuary area of the catchment. It is not clear whether (3)H released during test operation of the plant with actual spent nuclear fuel affected the (3)H concentrations observed in this study. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Determination of the hydraulic residence time of trickling filters using radiotracer experiments

    Energy Technology Data Exchange (ETDEWEB)

    Debien, Bruno R.; Ferreira, Ladislau M.; Barreto, Alberto A.; Pinto, Amenonia M.F., E-mail: brunordebien@gmail.com [Universidade Federal de Minas Gerais (UFMG), Minas Gerais, MG (Brazil). Dept. de Geografia. Lab. de Geomorfologia; Moreira, Rubens M., E-mail: aab@cdtn.br, E-mail: amfp@cdtn.br, E-mail: rubens@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    Trickling filters (TF) are bioreactors fulfilled with inert materials working as support for biofilm development, and have been used in a large scale in wastewater treatment for organic matter, ammonia nitrogen and nitrate removal. TF's can be widely used in Brazil, especially because of its simplicity and operational low cost. The efficiency of pollutants removal processes depends on the water flow dynamics inside the reactor. For this reason, in the present work the mean residence time of two TF's containing different support materials were determined by means of tracer testes. The radioisotope 82Br - a gamma radiation emitter, produced from soluble potassium bromide irradiated in the TRIGA reactor at the Centre for the Development of Nuclear Energy (CDTN) - was used as a pseudo-conservative tracer for the comparative study of aqueous phase flow dynamics in both TF's. Mean residence time for the first TF (containing a single support material) was 0,3 hours, much smaller than the value obtained for the second TF (containing two alternated support materials), around 2 hours. These results were already expected, once the alternated material is denser than the single one, and are very important for numerical modeling studies aiming to determine the kinetic constant for removal of the pollutants cited above. (author)

  3. Chemotaxis Increases the Residence Time Distribution of Bacteria in Granular Media Containing Distributed Contaminant Sources

    Science.gov (United States)

    Adadevoh, J.; Triolo, S.; Ramsburg, C. A.; Ford, R.

    2015-12-01

    The use of chemotactic bacteria in bioremediation has the potential to increase access to, and biotransformation of, contaminant mass within the subsurface environment. This laboratory-scale study aimed to understand and quantify the influence of chemotaxis on residence times of pollutant-degrading bacteria within homogeneous treatment zones. Focus was placed on a continuous flow sand-packed column system in which a uniform distribution of naphthalene crystals created distributed sources of dissolved phase contaminant. A 10 mL pulse of Pseudomonas putida G7, which is chemotactic to naphthalene, and Pseudomonas putida G7 Y1, a non-chemotactic mutant strain, were simultaneously introduced into the sand-packed column at equal concentrations. Breakthrough curves obtained for the bacteria from column experiments conducted with and without naphthalene were used to quantify the effect of chemotaxis on transport parameters. In the presence of the chemoattractant, longitudinal dispersivity of PpG7 increased by a factor of 3 and percent recovery decreased from 21% to 12%. The results imply that pore-scale chemotaxis responses are evident at an interstitial fluid velocity of 1.7 m/d, which is within the range of typical groundwater flow. Within the context of bioremediation, chemotaxis may work to enhance bacterial residence times in zones of contamination thereby improving treatment.

  4. Can a combination of average of normals and "real time" External Quality Assurance replace Internal Quality Control?

    Science.gov (United States)

    Badrick, Tony; Graham, Peter

    2018-03-28

    Internal Quality Control and External Quality Assurance are separate but related processes that have developed independently in laboratory medicine over many years. They have different sample frequencies, statistical interpretations and immediacy. Both processes have evolved absorbing new understandings of the concept of laboratory error, sample material matrix and assay capability. However, we do not believe at the coalface that either process has led to much improvement in patient outcomes recently. It is the increasing reliability and automation of analytical platforms along with improved stability of reagents that has reduced systematic and random error, which in turn has minimised the risk of running less frequent IQC. We suggest that it is time to rethink the role of both these processes and unite them into a single approach using an Average of Normals model supported by more frequent External Quality Assurance samples. This new paradigm may lead to less confusion for laboratory staff and quicker responses to and identification of out of control situations.

  5. The Removal of Aquacultural Wastes by Foams Separator from Sea Water II. The Effect of Hydraulic Residence Time

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Kuen Hack; Kim, Byong Jin; Kim, Yong Ha; Yi, Gyeongbeom; Lim, Jung Heok [Department of Chemical Engineering, Pukyong National University, Pusan (Korea); Kim, Sung Koo [Department of Biotechnology and Bioengineering, Pukyong National University, Pusan (Korea)

    2001-04-01

    Experimental investigations on the effect of the hydraulic residence time(HRT) for the removal of aquacultural waste, such as protein, total suspended solids(TSS), chemical oxygen demand(COD), turbidity and total ammonia nitrogen(TAN) from sea water were carried out by using foam separator. The foam separator as an aerator was also evaluated for increasing dissolved oxygen concentration. The increase in hydraulic residence time increased the removal efficiencies of aquacultural waste. Optimum hydraulic residence time was 0.48 min and the highest protein removal rate was 10.25 g/m{sup 3} min. The changes of removal rates and efficiencies of TSS, COD and turbidity were similar to proteins. The hydraulic residence time for highest overall oxygen mass transfer coefficient was the optimum condition for the highest protein removal rate. 23 refs., 15 figs., 1 tab.

  6. The significance of oxygen as oxides and hydroxides in controlling the abundance and residence times of elements in seawater

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.

    A model is presented which signifies the role of oxygen (as oxides and hydroxides) in controlling the composition of seawater. respective concentration and residence times for the unknown elements can be estimated. Geometric and statistical indices...

  7. Prevalence and Cost of Full-Time Research Fellowships During General Surgery Residency – A National Survey

    Science.gov (United States)

    Robertson, Charles M.; Klingensmith, Mary E.; Coopersmith, Craig M.

    2009-01-01

    Structured Abstract Objective To quantify the prevalence, outcomes, and cost of surgical resident research. Summary Background Data General surgery is unique among graduate medical education programs because a large percentage of residents interrupt their clinical training to spend 1-3 years performing full-time research. No comprehensive data exists on the scope of this practice. Methods Survey sent to all 239 program directors of general surgery residencies participating in the National Resident Matching Program. Results Response rate was 200/239 (84%). A total of 381 out of 1052 trainees (36%) interrupt residency to pursue full-time research. The mean research fellowship length is 1.7 years, with 72% of trainees performing basic science research. A significant association was found between fellowship length and post-residency activity, with a 14.7% increase in clinical fellowship training and a 15.2% decrease in private practice positions for each year of full-time research (p<0.0001). Program directors at 31% of programs reported increased clinical duties for research fellows as a result of ACGME work hour regulations for clinical residents, while a further 10% of programs are currently considering such changes. It costs $41.5 million to pay the 634 trainees who perform research fellowships each year, the majority of which is paid for by departmental funds (40%) and institutional training grants (24%). Conclusions Interrupting residency to perform a research fellowship is a common and costly practice among general surgery residents. While performing a research fellowship is associated with clinical fellowship training after residency, it is unclear to what extent this practice leads to the development of surgical investigators after post-graduate training. PMID:19106692

  8. Photo control of transport properties in a disordered wire: Average conductance, conductance statistics, and time-reversal symmetry

    International Nuclear Information System (INIS)

    Kitagawa, Takuya; Oka, Takashi; Demler, Eugene

    2012-01-01

    In this paper, we study the full conductance statistics of a disordered 1D wire under the application of light. We develop the transfer matrix method for periodically driven systems to analyze the conductance of a large system with small frequency of light, where coherent photon absorptions play an important role to determine not only the average but also the shape of conductance distributions. The average conductance under the application of light results from the competition between dynamic localization and effective dimension increase, and shows non-monotonic behavior as a function of driving amplitude. On the other hand, the shape of conductance distribution displays a crossover phenomena in the intermediate disorder strength; the application of light dramatically changes the distribution from log-normal to normal distributions. Furthermore, we propose that conductance of disordered systems can be controlled by engineering the shape, frequency and amplitude of light. Change of the shape of driving field controls the time-reversals symmetry and the disordered system shows analogous behavior as negative magneto-resistance known in static weak localization. A small change of frequency and amplitude of light leads to a large change of conductance, displaying giant opto-response. Our work advances the perspective to control the mean as well as the full conductance statistics by coherently driving disordered systems. - Highlights: ► We study conductance of disordered systems under the application of light. ► Full conductance distributions are obtained. ► A transfer matrix method is developed for driven systems. ► Conductances are dramatically modified upon the application of light. ► Time-reversal symmetry can also be controlled by light application.

  9. The effect of residence time on the dynamics of a condensating aerosol in a Hiemenz-type stagnation flow

    Science.gov (United States)

    Alshaarawi, Amjad; Zhou, Kun; Scribano, Gianfranco; Attili, Antonio; Bisetti, Fabrizio; Clean Combustion Research Center Team

    2013-11-01

    The effect of residence time on the formation and growth of a condensating aerosol is simulated in a Hiemenz-type stagnation flow setup, for which a unique and well-defined time scale characterizes the velocity field. In this configuration, a hot stream saturated with dibutyle phthalate (DBP) vapor mixes with a cold dry stream. A mixing layer forms at the stagnation plane triggering supersaturation and droplets are generated by homogeneous nucleation. Aerosol dynamics are simulated using the Quadrature Method of Moments (QMOM). Two regimes related to the flow residence time are observed, i.e., a nucleation regime and a condensation regime. The nucleation regime, at short residence times, is characterized by the consumption of DBP vapor into droplets having a negligible effect on the vapor phase. In this regime, both the number density and volume fraction of droplets increase with residence time. In the condensation regime, at long residence times, vapor condensation consumes the vapor phase considerably. For longer residence times, more vapor is consumed, resulting in lower number densities due to the lower nucleation rates, whereas the volume fraction saturates.

  10. Temporal evolution and variability of dissolved inorganic nitrogen in beach pore water revealed using radon residence times.

    Science.gov (United States)

    Goodridge, Blair M; Melack, John M

    2014-12-16

    We coupled measurements of beach pore water residence time, determined using the radioisotopic tracer (222)Rn, with dissolved carbon and nitrogen chemistry to identify the temporal evolution and variability of dissolved inorganic nitrogen (DIN) concentrations in beach pore water along the Santa Barbara, California coastline. Pore water dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) ratios (DOC:TDN) were negative exponentially correlated with residence time. Mean pore water residence times were positively correlated with tidal amplitudes, and ranged from 4.4 to 6.4 days. We used this range in mean residence times to model radon residence time distributions (RTDs), and integrated them with modeled DIN vs residence time relationships (DIN-temporal evolution, or DIN-te curves) to derive volume-weighted mean (VWM) DIN concentrations. We observed 1.2-fold and 5.2-fold differences (20% and 420% increases) in VWM DIN concentrations over the range in modeled RTDs and DIN-te curves, respectively, and a maximum 6.4-fold difference (540% increase) in VWM DIN concentrations for an interactive shift in the RTD and the DIN-te curve. Our study suggests that accounting for temporal variability in the RTD and DIN concentration of pore water is necessary to obtain more accurate estimates of DIN delivery to coastal oceans.

  11. Coupled Long-Term Simulation of Reach-Scale Water and Heat Fluxes Across the River-Groundwater Interface for Retrieving Hyporheic Residence Times and Temperature Dynamics

    Science.gov (United States)

    Munz, Matthias; Oswald, Sascha E.; Schmidt, Christian

    2017-11-01

    Flow patterns in conjunction with seasonal and diurnal temperature variations control ecological and biogeochemical conditions in hyporheic sediments. In particular, hyporheic temperatures have a great impact on many temperature-sensitive microbial processes. In this study, we used 3-D coupled water flow and heat transport simulations applying the HydroGeoSphere code in combination with high-resolution observations of hydraulic heads and temperatures to quantify reach-scale water and heat flux across the river-groundwater interface and hyporheic temperature dynamics of a lowland gravel bed river. The model was calibrated in order to constrain estimates of the most sensitive model parameters. The magnitude and variations of the simulated temperatures matched the observed ones, with an average mean absolute error of 0.7°C and an average Nash Sutcliffe efficiency of 0.87. Our results indicate that nonsubmerged streambed structures such as gravel bars cause substantial thermal heterogeneity within the saturated sediment at the reach scale. Individual hyporheic flow path temperatures strongly depend on the flow path residence time, flow path depth, river, and groundwater temperature. Variations in individual hyporheic flow path temperatures were up to 7.9°C, significantly higher than the daily average (2.8°C), but still lower than the average seasonal hyporheic temperature difference (19.2°C). The distribution between flow path temperatures and residence times follows a power law relationship with exponent of about 0.37. Based on this empirical relation, we further estimated the influence of hyporheic flow path residence time and temperature on oxygen consumption which was found to partly increase by up to 29% in simulations.

  12. Groundwater residence times in Shenandoah National Park, Blue Ridge Mountains, Virginia, USA: A multi-tracer approach

    Science.gov (United States)

    Plummer, Niel; Busenberg, E.; Böhlke, J.K.; Nelms, D.L.; Michel, R.L.; Schlosser, P.

    2001-01-01

    seasonally. Concentrations of He and Ne in excess of solubility equilibrium indicate that the dissolved gases are not fractionated. The seasonal variations in N2–Ar temperatures suggest shallow, seasonal recharge, and the excess He and Ne data suggest waters mostly confined to gas exchange in the shallow, mountain-slope, water-table spring systems. Water from wells in the fractured rock contains up to 8 cm3 kg−1 of excess air with ages in the range of 0–25 years. Transient responses in specific conductance and temperature were observed in spring discharge within several hours of large precipitation events in September, 1999; both parameters increased initially, then decreased to values below pre-storm base-flow values. The groundwater residence times indicate that flushing rates of mobile atmospheric constituents through groundwater to streams draining the higher elevations in SNP average less than 3 years in base-flow conditions.

  13. An Exploration of Discontinuous Time Synchronous Averaging for Helicopter HUMS Using Cruise and Terminal Area Vibration Data

    Science.gov (United States)

    Huff, Edward M.; Mosher, Marianne; Barszcz, Eric

    2002-01-01

    Recent research using NASA Ames AH-1 and OH-58C helicopters, and NASA Glenn test rigs, has shown that in-flight vibration data are typically non-stationary [l-4]. The nature and extent of this non-stationarity is most likely produced by several factors operating simultaneously. The aerodynamic flight environment and pilot commands provide continuously changing inputs, with a complex dynamic response that includes automatic feedback control from the engine regulator. It would appear that the combined effects operate primarily through an induced torque profile, which causes concomitant stress modulation at the individual internal gear meshes in the transmission. This notion is supported by several analyses, which show that upwards of 93% of the vibration signal s variance can be explained by knowledge of torque alone. That this relationship is stronger in an AH-1 than an OH-58, where measured non-stationarity is greater, suggests that the overall mass of the vehicle is an important consideration. In the lighter aircraft, the unsteady aerodynamic influences transmit relatively greater unsteady dynamic forces on the mechanical components, quite possibly contributing to its greater non-stationarity . In a recent paper using OH-58C pinion data [5], the authors have shown that in computing a time synchronous average (TSA) for various single-value metric computations, an effective trade-off can be obtained between sample size and measured stationarity by using data from only a single mesh cycle. A mesh cycle, which is defined as the number of rotations required for the gear teeth to return to their original mating position, has the property of representing all of the discrete phase angles of the opposing gears exactly once in the average. Measured stationarity is probably maximized because a single mesh cycle of the pinion gear occurs over a very short span of time, during which time-dependent non-stationary effects are kept to a minimum. Clearly, the advantage of local

  14. Residence time distribution measurements in a pilot-scale poison tank using radiotracer technique.

    Science.gov (United States)

    Pant, H J; Goswami, Sunil; Samantray, J S; Sharma, V K; Maheshwari, N K

    2015-09-01

    Various types of systems are used to control the reactivity and shutting down of a nuclear reactor during emergency and routine shutdown operations. Injection of boron solution (borated water) into the core of a reactor is one of the commonly used methods during emergency operation. A pilot-scale poison tank was designed and fabricated to simulate injection of boron poison into the core of a reactor along with coolant water. In order to design a full-scale poison tank, it was desired to characterize flow of liquid from the tank. Residence time distribution (RTD) measurement and analysis was adopted to characterize the flow dynamics. Radiotracer technique was applied to measure RTD of aqueous phase in the tank using Bromine-82 as a radiotracer. RTD measurements were carried out with two different modes of operation of the tank and at different flow rates. In Mode-1, the radiotracer was instantaneously injected at the inlet and monitored at the outlet, whereas in Mode-2, the tank was filled with radiotracer and its concentration was measured at the outlet. From the measured RTD curves, mean residence times (MRTs), dead volume and fraction of liquid pumped in with time were determined. The treated RTD curves were modeled using suitable mathematical models. An axial dispersion model with high degree of backmixing was found suitable to describe flow when operated in Mode-1, whereas a tanks-in-series model with backmixing was found suitable to describe flow of the poison in the tank when operated in Mode-2. The results were utilized to scale-up and design a full-scale poison tank for a nuclear reactor. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. BATSE Observations of Gamma-Ray Burst Spectra. Part 3; Low-Energy Behavior of Time-Averaged Spectra

    Science.gov (United States)

    Preece, R. D.; Briggs, M. S.; Pendleton, G. N.; Paciesas, W. S.; Matteson, J. L.; Band, D. L.; Skelton, R. T.; Meegan, C. A.

    1996-01-01

    We analyze time-averaged spectra from 86 bright gamma-ray bursts from the first 5 years of the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory to determine whether the lowest energy data are consistent with a standard spectra form fit to the data at all energies. The BATSE Spectroscopy Detectors have the capability to observe photons as low as 5 keV. Using the gamma-ray burst locations obtained with the BATSE Large Area Detectors, the Spectroscopy Detectors' low-energy response can be modeled accurately. This, together with a postlaunch calibration of the lowest energy Spectroscopy Detector discriminator channel, which can lie in the range 5-20 keV, allows spectral deconvolution over a broad energy range, approx. 5 keV to 2 MeV. The additional coverage allows us to search for evidence of excess emission, or for a deficit, below 20 keV. While no burst has a significant (greater than or equal to 3 sigma) deficit relative to a standard spectra model, we find that 12 bursts have excess low-energy emission, ranging between 1.2 and 5.8 times the model flux, that exceeds 5 sigma in significance. This is evidence for an additional low-energy spectral component in at least some bursts, or for deviations from the power-law spectral form typically used to model gamma-ray bursts at energies below 100 keV.

  16. The Use of the Time Average Visibility for Analyzing HERA-19 Commissioning Data: Effects of Non-Redundancy

    Science.gov (United States)

    Benefo, Roshan; Gallardo, Samavarti; Aguirre, James; La Plante, Paul; HERA Collaboration

    2018-01-01

    The Hydrogen Epoch of Reionization Array (HERA) is a radio telescope situated in South Africa designed to observe the universe from redshifts 13 through 6, in order to detect the emission of the 21 cm line from the hydrogen spin-flip transition. We perform 21 cm cosmology due to its relation with reionization; by detecting this emission line, we can identify the timing of reionization, and understand more about the nature of the universe during the birth of the first stars and galaxies. With that, we can understand the heating conditions of the initial universe, providing us a larger picture of the conditions that created the large-scale structure of the universe we observe today. The HERA array currently consists of 19 antennas, spaced in a hexagonal grid pattern. We consider a robust observable, the time-averaged visibility (TAV), which is in principle sensitive to variations in the beam pattern between antenna elements and is easier to measure than the beam pattern itself. We use this TAV to explore the non-redundancy of baselines in the HERA array due either to cross-coupling between antennas (probed by antenna location in the array) or non-uniformity in their manufacture. The TAV may provide a simple way of verifying improvements in antenna element redundancy.

  17. Characterisation and Implications of an Exceptionally Weak Time-averaged Geomagnetic field in the Devonian (360-420 Ma)

    Science.gov (United States)

    Biggin, Andy; Hawkins, Louise; Shcherbakova, Valia; Anwar, Taslima; Kravchinsky, Vadim; Shatsillo, Andrey; Shcherbakov, Valeriy; Veselovskiy, Roman; Pavlov, Vladimir

    2017-04-01

    Variations in the time-averaged dipole moment of Earth have the potential to inform us about the long-term state of the geodynamo and its response to mantle forcing and the thermal evolution of the core. Rocks of Devonian age (360-420 Ma) are well-known for occasionally producing erratic palaeomagnetic directions but measurements defining the intensity of the magnetic field during this period are sparse and of limited reliability. Recent collaborations between the Universities of Liverpool, Alberta and the Russian Academy of Sciences have produced a wealth of new palaeointensity data from this time period using samples collected from northern and southern Siberia and the Kola Penninsula. With near universality, the palaeointensities recovered from these rocks are lower than the field strength observed anywhere on Earth today. In many cases, the recovered palaeointensities are exceptionally low (Jurassic and Cretaceous and approximately 200 Myr earlier during the Cambrian and Ordovician. We therefore have increasing evidence of a recurring phenomenon in palaeomagnetic behaviour that most likely reflects a quasi-periodic process in the lower mantle producing changes in the pattern and/or magnitude of core-mantle heat flow. Superplume growth and collapse and the occurrence of major episodes of true polar wander are two plausible mechanisms which could potentially be causally linked and certainly deserve further investigation.

  18. Trends in Average Living Children at the Time of Terminal Contraception: A Time Series Analysis Over 27 Years Using ARIMA (p, d, q) Nonseasonal Model.

    Science.gov (United States)

    Mumbare, Sachin S; Gosavi, Shriram; Almale, Balaji; Patil, Aruna; Dhakane, Supriya; Kadu, Aniruddha

    2014-10-01

    India's National Family Welfare Programme is dominated by sterilization, particularly tubectomy. Sterilization, being a terminal method of contraception, decides the final number of children for that couple. Many studies have shown the declining trend in the average number of living children at the time of sterilization over a short period of time. So this study was planned to do time series analysis of the average children at the time of terminal contraception, to do forecasting till 2020 for the same and to compare the rates of change in various subgroups of the population. Data was preprocessed in MS Access 2007 by creating and running SQL queries. After testing stationarity of every series with augmented Dickey-Fuller test, time series analysis and forecasting was done using best-fit Box-Jenkins ARIMA (p, d, q) nonseasonal model. To compare the rates of change of average children in various subgroups, at sterilization, analysis of covariance (ANCOVA) was applied. Forecasting showed that the replacement level of 2.1 total fertility rate (TFR) will be achieved in 2018 for couples opting for sterilization. The same will be achieved in 2020, 2016, 2018, and 2019 for rural area, urban area, Hindu couples, and Buddhist couples, respectively. It will not be achieved till 2020 in Muslim couples. Every stratum of population showed the declining trend. The decline for male children and in rural area was significantly faster than the decline for female children and in urban area, respectively. The decline was not significantly different in Hindu, Muslim, and Buddhist couples.

  19. Trends in average living children at the time of terminal contraception: A time series analysis over 27 years using ARIMA (p, d, q nonseasonal model

    Directory of Open Access Journals (Sweden)

    Sachin S Mumbare

    2014-01-01

    Full Text Available Background: India′s National Family Welfare Programme is dominated by sterilization, particularly tubectomy. Sterilization, being a terminal method of contraception, decides the final number of children for that couple. Many studies have shown the declining trend in the average number of living children at the time of sterilization over a short period of time. So this study was planned to do time series analysis of the average children at the time of terminal contraception, to do forecasting till 2020 for the same and to compare the rates of change in various subgroups of the population. Materials and Methods: Data was preprocessed in MS Access 2007 by creating and running SQL queries. After testing stationarity of every series with augmented Dickey-Fuller test, time series analysis and forecasting was done using best-fit Box-Jenkins ARIMA (p, d, q nonseasonal model. To compare the rates of change of average children in various subgroups, at sterilization, analysis of covariance (ANCOVA was applied. Results: Forecasting showed that the replacement level of 2.1 total fertility rate (TFR will be achieved in 2018 for couples opting for sterilization. The same will be achieved in 2020, 2016, 2018, and 2019 for rural area, urban area, Hindu couples, and Buddhist couples, respectively. It will not be achieved till 2020 in Muslim couples. Conclusion: Every stratum of population showed the declining trend. The decline for male children and in rural area was significantly faster than the decline for female children and in urban area, respectively. The decline was not significantly different in Hindu, Muslim, and Buddhist couples.

  20. Residence time, dispersal, and harvest of waterfowl using a radioactive leaching pond in southeastern Idaho

    International Nuclear Information System (INIS)

    Browers, H.W. Jr.; Flake, L.D.

    1983-01-01

    A study was initiated in the fall of 1980 to determine residence times, dispersal, and harvest of waterfowl using the Test Reactor Area (TRA) radioactive leaching pond complex on the Idaho National Engineering Laboratory (INEL) site. Attempts were made to capture and band waterfowl using the ponds during migration. Three common goldeneyes (Bucephala clangula) and six mallards (Anas platyrynchos) were captured in the fall of 1980. Three mallards were also captured in the fall of 1981. Two bands have been recovered to date. In addition, daily observations were made from August to December 1980 and from October to December 1981 and the number and species of waterfowl were recorded. As of December 15, 1981, 665 waterfowl representing 14 species had been observed. However,the total number of waterfowl observed does not represent an accurate census due to recounts of some individuals

  1. Devolatilization kinetics of woody biomass at short residence times and high heating rates and peak temperatures

    DEFF Research Database (Denmark)

    Johansen, Joakim M.; Gadsbøll, Rasmus; Thomsen, Jesper

    2016-01-01

    were conducted on a laboratory laminar entrained flow reactor (LFR) using solid fuel feed rates on the order of 10-20mgh-1. Employing a simple single step first order (SFOR) mechanism with an Arrhenius type rate expression, the best fit of the pyrolysis kinetics was found to be: A=18.9×103s-1, Ea=21305......This work combines experimental and computational fluid dynamics (CFD) results to derive global kinetics for biomass (pine wood) devolatilization during heating rates on the order of 105Ks-1, bulk flow peak temperatures between 1405 and 1667K, and particle residence times below 0.1s. Experiments......Jmol-1. The accuracy of the derived global kinetics was supported by comparing predictions to experimental results from a 15kW furnace. The work emphasizes the importance of characterizing the temperature history of the biomass particles when deriving pyrolysis kinetics. The present results indicate...

  2. Recent extensions of the residence time distribution concept: unsteady state conditions and hydrodynamic model developments

    Directory of Open Access Journals (Sweden)

    Claudel S.

    2000-01-01

    Full Text Available Two recent extensions of the residence time distribution concept are developed. The first one concerns the use of this method under transient conditions, a concept theoretically treated but rarely confirm by relevant experiments. In the present work, two experimental set-ups have been used to verify some limits of the concept. The second extension is devoted to the development of hydrodynamic models. Up to now, the hydrodynamics of the process are either determined by simple models (mixing cells in series, plug flow reactor with axial dispersion or by the complex calculation of the velocity profile obtained via the Navier-Stokes equations. An alternative is to develop a hydrodynamic model by use of a complex network of interconnected elementary reactors. Such models should be simple enough to be derived easily and sufficiently complex to give a good representation of the behavior of the process.

  3. Paleosecular variation and time-averaged field recorded in late Pliocene-Holocene lava flows from Mexico

    Science.gov (United States)

    Mejia, V.; BöHnel, H.; Opdyke, N. D.; Ortega-Rivera, M. A.; Lee, J. K. W.; Aranda-Gomez, J. J.

    2005-07-01

    This paper presents results from 13 paleomagnetic sites from an area west of Mexico City and 7 sites from an area of dispersed monogenetic volcanism in the state of San Luis Potosi, accompanied by seven 40Ar/39Ar radiometric dates. An analysis of secular variation and time-averaged paleomagnetic field in the Trans-Mexican Volcanic Belt (TMVB), using compiled data both newly obtained and from the literature, is presented. Interpretation can best be constrained after excluding from the data set sites that appear to be tectonically affected. The selected data include 187 sites of late Pliocene-Holocene age. The mean direction among these sites is Dec = 358.8°, Inc = 31.6°, α95 = 2.0°, k = 29. This direction does not overlap the expected geocentric axial dipole (GAD) but is consistent with a GAD plus a 5% quadrupole. The virtual geomagnetic pole scatter of this group of sites (12.7°, with lower and upper 95% confidence limits of 11.9° and 14.1°) is consistent with the value expected from Model G (13.6°).

  4. Comparison of Spot and Time Weighted Averaging (TWA Sampling with SPME-GC/MS Methods for Trihalomethane (THM Analysis

    Directory of Open Access Journals (Sweden)

    Don-Roger Parkinson

    2016-02-01

    Full Text Available Water samples were collected and analyzed for conductivity, pH, temperature and trihalomethanes (THMs during the fall of 2014 at two monitored municipal drinking water source ponds. Both spot (or grab and time weighted average (TWA sampling methods were assessed over the same two day sampling time period. For spot sampling, replicate samples were taken at each site and analyzed within 12 h of sampling by both Headspace (HS- and direct (DI- solid phase microextraction (SPME sampling/extraction methods followed by Gas Chromatography/Mass Spectrometry (GC/MS. For TWA, a two day passive on-site TWA sampling was carried out at the same sampling points in the ponds. All SPME sampling methods undertaken used a 65-µm PDMS/DVB SPME fiber, which was found optimal for THM sampling. Sampling conditions were optimized in the laboratory using calibration standards of chloroform, bromoform, bromodichloromethane, dibromochloromethane, 1,2-dibromoethane and 1,2-dichloroethane, prepared in aqueous solutions from analytical grade samples. Calibration curves for all methods with R2 values ranging from 0.985–0.998 (N = 5 over the quantitation linear range of 3–800 ppb were achieved. The different sampling methods were compared for quantification of the water samples, and results showed that DI- and TWA- sampling methods gave better data and analytical metrics. Addition of 10% wt./vol. of (NH42SO4 salt to the sampling vial was found to aid extraction of THMs by increasing GC peaks areas by about 10%, which resulted in lower detection limits for all techniques studied. However, for on-site TWA analysis of THMs in natural waters, the calibration standard(s ionic strength conditions, must be carefully matched to natural water conditions to properly quantitate THM concentrations. The data obtained from the TWA method may better reflect actual natural water conditions.

  5. Time average neutralized migma: A colliding beam/plasma hybrid physical state as aneutronic energy source — A review

    Science.gov (United States)

    Maglich, Bogdan C.

    1988-08-01

    A D + beam of kinetic energy Ti = 0.7 MeV was stored in a "simple mirror" magnetic field as self-colliding orbits or migma and neutralized by ambient, oscillating electrons whose bounce frequencies were externally controlled. Space charge density was exceeded by an order of magnitude without instabilities. Three nondestructive diagnostic methods allowed measurements of ion orbit distribution, ion storage times, ion energy distribution, nuclear reaction rate, and reaction product spectrum. Migma formed a disc 20 cm in diameter and 0.5 cm thick. Its ion density was sharply peaked in the center; the ion-to-electron temperature ratio was TiTe ˜ 10 3; ion-electron temperature equilibrium was never reached. The volume average and central D + density were n = 3.2 × 10 9 cm -3 and nc = 3 × 10 10 cm -3 respectively, compared to the space charge limit density nsc = 4 × 10 8 cm -3. The energy confinement time was τc = 20-30 s, limited by the change exchange reactions with the residual gas in the vacuum (5 × 10 -9 Torr). The ion energy loss rate was 1.4 keV/s. None of the instabilities that were observed in mirrors at several orders of magnitude lower density occurred. The proton energy spectrum for dd + d → T + p + 4 MeV shows that dd collided at an average crossing angle of 160°. Evidence for exponential density buildup has also been observed. Relative to Migma III results and measured in terms of the product of ion energy E, density n, and confinement time τ, device performance was improved by a factor of 500. Using the central fast ion density, we obtained the triple product: Tnτ ≅ 4 × 10 14 keV s cm -3, which is greater than that of the best fusion devices. The luminosity (collision rate per unit cross section) was ˜ 10 29 cm -2s -1, with o.7 A ion current through the migma center. The stabilizing features of migma are: (1) large Larmor radius; (2) small canonical angular momentum; (3) short axial length z (disc shape); (4) nonadiabatic motions in r and z

  6. Low to Moderate Average Alcohol Consumption and Binge Drinking in Early Pregnancy: Effects on Choice Reaction Time and Information Processing Time in Five-Year-Old Children.

    Directory of Open Access Journals (Sweden)

    Tina R Kilburn

    Full Text Available Deficits in information processing may be a core deficit after fetal alcohol exposure. This study was designed to investigate the possible effects of weekly low to moderate maternal alcohol consumption and binge drinking episodes in early pregnancy on choice reaction time (CRT and information processing time (IPT in young children.Participants were sampled based on maternal alcohol consumption during pregnancy. At the age of 60-64 months, 1,333 children were administered a modified version of the Sternberg paradigm to assess CRT and IPT. In addition, a test of general intelligence (WPPSI-R was administered.Adjusted for a wide range of potential confounders, this study showed no significant effects of average weekly maternal alcohol consumption during pregnancy on CRT or IPT. There was, however, an indication of slower CRT associated with binge drinking episodes in gestational weeks 1-4.This study observed no significant effects of average weekly maternal alcohol consumption during pregnancy on CRT or IPT as assessed by the Sternberg paradigm. However, there were some indications of CRT being associated with binge drinking during very early pregnancy. Further large-scale studies are needed to investigate effects of different patterns of maternal alcohol consumption on basic cognitive processes in offspring.

  7. Residence times and alluvial architecture of a sediment superslug in response to different flow regimes

    Science.gov (United States)

    Moody, John A.

    2017-10-01

    A superslug was deposited in a basin in the Colorado Front Range Mountains as a consequence of an extreme flood following a wildfire disturbance in 1996. The subsequent evolution of this superslug was measured by repeat topographic surveys (31 surveys from 1996 through 2014) of 18 cross sections approximately uniformly spaced over 1500 m immediately above the basin outlet. These surveys allowed the identification within the superslug of chronostratigraphic units deposited and eroded by different geomorphic processes in response to different flow regimes. Over the time period of the study, the superslug went through aggradation, incision, and stabilization phases that were controlled by a shift in geomorphic processes from generally short-duration, episodic, large-magnitude floods that deposited new chronostratigraphic units to long-duration processes that eroded units. These phases were not contemporaneous at each channel cross section, which resulted in a complex response that preserved different chronostratigraphic units at each channel cross section having, in general, two dominant types of alluvial architecture-laminar and fragmented. Age and transit-time distributions for these two alluvial architectures evolved with time since the extreme flood. Because of the complex shape of the distributions they were best modeled by two-parameter Weibull functions. The Weibull scale parameter approximated the median age of the distributions, and the Weibull shape parameter generally had a linear relation that increased with time since the extreme flood. Additional results indicated that deposition of new chronostratigraphic units can be represented by a power-law frequency distribution, and that the erosion of units decreases with depth of burial to a limiting depth. These relations can be used to model other situations with different flow regimes where vertical aggradation and incision are dominant processes, to predict the residence time of possible contaminated

  8. Exposure in emergency general surgery in a time-based residency ...

    African Journals Online (AJOL)

    Objective: This paper aimed to characterize the resident exposure to acute general surgical conditions during a three-months rotation in a general surgical unit. Setting: The Department of Surgery, University of Nairobi and Kenyatta National Referral and Teaching Hospital in Nairobi. MethodS: Four residents (in their first to ...

  9. Organizational and Individual Conditions Associated with Depressive Symptoms among Nursing Home Residents over Time

    Science.gov (United States)

    Cassie, Kimberly M.; Cassie, William E.

    2012-01-01

    Purpose: To examine the effect of organizational culture and climate on depressive symptoms among nursing home residents. Design and Methods: Using a pooled cross-sectional design, this study examines a sample of 23 nursing homes, 1,114 employees, and 5,497 residents. Depressive symptoms were measured using the Minimum Data Set, Depression Rating…

  10. Time-weighted average sampling of airborne propylene glycol ethers by a solid-phase microextraction device.

    Science.gov (United States)

    Shih, H C; Tsai, S W; Kuo, C H

    2012-01-01

    A solid-phase microextraction (SPME) device was used as a diffusive sampler for airborne propylene glycol ethers (PGEs), including propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), and dipropylene glycol monomethyl ether (DPGME). Carboxen-polydimethylsiloxane (CAR/PDMS) SPME fiber was selected for this study. A polytetrafluoroethylene (PTFE) tubing was used as the holder, and the SPME fiber assembly was inserted into the tubing as a diffusive sampler. The diffusion path length and area of the sampler were 0.3 cm and 0.00086 cm(2), respectively. The theoretical sampling constants at 30°C and 1 atm for PGME, PGMEA, and DPGME were 1.50 × 10(-2), 1.23 × 10(-2) and 1.14 × 10(-2) cm(3) min(-1), respectively. For evaluations, known concentrations of PGEs around the threshold limit values/time-weighted average with specific relative humidities (10% and 80%) were generated both by the air bag method and the dynamic generation system, while 15, 30, 60, 120, and 240 min were selected as the time periods for vapor exposures. Comparisons of the SPME diffusive sampling method to Occupational Safety and Health Administration (OSHA) organic Method 99 were performed side-by-side in an exposure chamber at 30°C for PGME. A gas chromatography/flame ionization detector (GC/FID) was used for sample analysis. The experimental sampling constants of the sampler at 30°C were (6.93 ± 0.12) × 10(-1), (4.72 ± 0.03) × 10(-1), and (3.29 ± 0.20) × 10(-1) cm(3) min(-1) for PGME, PGMEA, and DPGME, respectively. The adsorption of chemicals on the stainless steel needle of the SPME fiber was suspected to be one of the reasons why significant differences between theoretical and experimental sampling rates were observed. Correlations between the results for PGME from both SPME device and OSHA organic Method 99 were linear (r = 0.9984) and consistent (slope = 0.97 ± 0.03). Face velocity (0-0.18 m/s) also proved to have no effects on the sampler

  11. Hydrolysis evolution in a codigestion reactor at various hydraulic residence times

    Directory of Open Access Journals (Sweden)

    Gloria González

    2014-01-01

    Full Text Available The aim of this research is to study the influence of two different hydraulic residence times (HRT's, 5 and 10 days, on the process of hydrolysis-solubilization in a codigestion reactor. Tap water was used to simulate recirculation of a treated leachate. Organic solid waste (OSW from urban solid waste (USW and excess sludge from an urban wastewater treatment plant were first characterized and then treated together by anaerobic codigestion. This was done using a 27.2-L total volume pilot scale bioreactor, which was loaded with equal amounts (w/w of OSW and sludge to a total useful volume of 13-L. The bioreactor was filled with tap water to ensure high humidity. In order to assure suitable mixing and good microbial-substrate contact in the reactor, recirculation of treated effluent was maintained by continuous water flow. The influence of HRT on the process performance was determined through physicochemical characterization of the effluent. Results indicate that HRT is a determinant factor in the efficiency of the system. Reducing HRT increases hydrodynamics and solubilization kinetic rate of organic matter in the bioreactor. Stabilization time of solids is reduced from 20 to 10 days when HRT is shortened from 10 to 5 days.

  12. Plan for radionuclide tracer studies of the residence time distribution in the Wilsonville dissolver and preheater

    Energy Technology Data Exchange (ETDEWEB)

    Jolley, R.L.; Begovich, J.M.; Brashear, H.R.; Case, N.; Clark, T.G.; Emery, J.F.; Patton, B.D.; Rodgers, B.R.; Villiers-Fisher, J.F.; Watson, J.S.

    1983-12-01

    Stimulus-response measurements using radiotracers to measure residence time distribution (RTD) and hydrodynamic parameters for the preheaters and dissolvers at the Ft. Lewis Solvent Refined Coal (SRC) and the Exxon Donor Solvent (EDS) coal conversion pilot plants are reviewed. A plan is also presented for a series of radioactive tracer studies proposed for the Advanced Coal Liquefaction Facility at Wilsonville, Alabama, to measure the RTD for the preheater and dissolvers in the SRC-I mode. The tracer for the gas phase will be /sup 133/Xe, and /sup 198/Au (on carbonized resin or as an aqueous colloidal suspension) will be used as the slurry tracer. Four experimental phases are recommended for the RTD tracer studies: (1) preheater; (2) dissolver with 100% takeoff; (3) dissolver with 100% takeoff and solids withdrawal; and (4) dissolver with 50% takeoff. Eighteen gas-tracer and 22 liquid-tracer injections are projected to accomplish the four experimental phases. Two to four tracer injections are projected for preliminary tests to ensure the capability of safe injection of the radiotracers and the collection of statistically significant data. A complete projected cost and time schedule is provided, including procurement of necessary components, preparation of the radiotracers, assembly and testing of tracer injection apparatus and detection systems, onsite work and tracer injections, laboratory experimentation, data analysis, and report writing.

  13. Plan for radionuclide tracer studies of the residence time distribution in the Wilsonville dissolver and preheater

    International Nuclear Information System (INIS)

    Jolley, R.L.; Begovich, J.M.; Brashear, H.R.

    1983-12-01

    Stimulus-response measurements using radiotracers to measure residence time distribution (RTD) and hydrodynamic parameters for the preheaters and dissolvers at the Ft. Lewis Solvent Refined Coal (SRC) and the Exxon Donor Solvent (EDS) coal conversion pilot plants are reviewed. A plan is also presented for a series of radioactive tracer studies proposed for the Advanced Coal Liquefaction Facility at Wilsonville, Alabama, to measure the RTD for the preheater and dissolvers in the SRC-I mode. The tracer for the gas phase will be 133 Xe, and 198 Au (on carbonized resin or as an aqueous colloidal suspension) will be used as the slurry tracer. Four experimental phases are recommended for the RTD tracer studies: (1) preheater; (2) dissolver with 100% takeoff; (3) dissolver with 100% takeoff and solids withdrawal; and (4) dissolver with 50% takeoff. Eighteen gas-tracer and 22 liquid-tracer injections are projected to accomplish the four experimental phases. Two to four tracer injections are projected for preliminary tests to ensure the capability of safe injection of the radiotracers and the collection of statistically significant data. A complete projected cost and time schedule is provided, including procurement of necessary components, preparation of the radiotracers, assembly and testing of tracer injection apparatus and detection systems, onsite work and tracer injections, laboratory experimentation, data analysis, and report writing

  14. Residence times of groundwater and nitrate transport in coastal aquifer systems: Daweijia area, northeastern China

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dongmei [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China); National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Cao, Guoliang [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Center for Water Research, College of Engineering, Peking University, Beijing 100871 (China); McCallum, James [National Centre for Groundwater Research and Training, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); School of the Environment, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Song, Xianfang [Key Laboratory of Water Cycle & Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101 (China)

    2015-12-15

    Groundwater within the coastal aquifer systems of the Daweijia area in northeastern China is characterized by a large of variations (33–521 mg/L) in NO{sub 3}{sup −} concentrations. Elevated nitrate concentrations, in addition to seawater intrusion in the Daweijia well field, both attributable to anthropogenic activities, may impact future water-management practices. Chemical and stable isotopic (δ{sup 18}O, δ{sup 2}H) analysis, {sup 3}H and CFCs methods were applied to provide a better understanding of the relationship between the distribution of groundwater mean residence time (MRT) and nitrate transport, and to identify sources of nitrate concentrations in the complex coastal aquifer systems. There is a relatively narrow range of isotopic composition (ranging from − 8.5 to − 7.0‰) in most groundwater. Generally higher tritium contents observed in the wet season relative to the dry season may result from rapid groundwater circulation in response to the rainfall through the preferential flow paths. In the well field, the relatively increased nitrate concentrations of groundwater, accompanied by the higher tritium contents in the wet season, indicate the nitrate pollution can be attributed to domestic wastes. The binary exponential and piston-flow mixing model (BEP) yielded feasible age distributions based on the conceptual model. The good inverse relationship between groundwater MRTs (92–467 years) and the NO{sub 3}{sup −} concentrations in the shallow Quaternary aquifers indicates that elevated nitrate concentrations are attributable to more recent recharge for shallow groundwater. However, there is no significant relationship between the MRTs (8–411 years) and the NO{sub 3}{sup −} concentrations existing in the carbonate aquifer system, due to the complex hydrogeological conditions, groundwater age distributions and the range of contaminant source areas. Nitrate in the groundwater system without denitrification effects could accumulate and be

  15. How Do Residents Spend Their Shift Time? A Time and Motion Study With a Particular Focus on the Use of Computers.

    Science.gov (United States)

    Mamykina, Lena; Vawdrey, David K; Hripcsak, George

    2016-06-01

    To understand how much time residents spend using computers compared with other activities, and what residents use computers for. This time and motion study was conducted in June and July 2010 at NewYork-Presbyterian/Columbia University Medical Center with seven residents (first-, second-, and third-year) on the general medicine service. An experienced observer shadowed residents during a single day shift, captured all their activities using an iPad application, and took field notes. The activities were captured using a validated taxonomy of clinical activities, expanded to describe computer-based activities with a greater level of detail. Residents spent 364.5 minutes (50.6%) of their shift time using computers, compared with 67.8 minutes (9.4%) interacting with patients. In addition, they spent 292.3 minutes (40.6%) talking with others in person, 186.0 minutes (25.8%) handling paper notes, 79.7 minutes (11.1%) in rounds, 80.0 minutes (11.1%) walking or waiting, and 54.0 minutes (7.5%) talking on the phone. Residents spent 685 minutes (59.6%) multitasking. Computer-based documentation activities amounted to 189.9 minutes (52.1%) of all computer-based activities time, with 128.7 minutes (35.3%) spent writing notes and 27.3 minutes (7.5%) reading notes composed by others. The study showed that residents spent considerably more time interacting with computers (over 50% of their shift time) than in direct contact with patients (less than 10% of their shift time). Some of this may be due to an increasing reliance on computing systems for access to patient data, further exacerbated by inefficiencies in the design of the electronic health record.

  16. Time-motion studies of internal medicine residents' duty hours: a systematic review and meta-analysis.

    Science.gov (United States)

    Leafloor, Cameron W; Lochnan, Heather A; Code, Catherine; Keely, Erin J; Rothwell, Deanna M; Forster, Alan J; Huang, Allen R

    2015-01-01

    Since the mid-1980s, medical residents' long duty hours have been under scrutiny as a factor affecting patient safety and the work environment for the residents. After several mandated changes in duty hours, it is important to understand how residents spend their time before proposing and implementing future changes. Time-motion methodology may provide reliable information on what residents do while on duty. The purpose of this study is to review all available literature pertaining to time-motion studies of internal medicine residents while on a medicine service and to understand how much of their time is apportioned to various categories of tasks, and also to determine the effects of the Accreditation Council for Graduate Medical Education (ACGME)-mandated duty hour changes on resident workflow in North America. Electronic bibliographic databases were searched for articles in English between 1941 and April 2013 reporting time-motion studies of internal medicine residents rotating through a general medicine service. Eight articles were included. Residents spent 41.8% of time in patient care activities, 18.1% communicating, 13.8% in educational activities, 19.7% in personal/other, and 6.6% in transit. North American data showed the following changes after the implementation of the ACGME 2003 duty hours standard: patient care activities from 41.8% to 40.8%, communication activities from 19.0% to 22.3%, educational activities from 17.7% to 11.6%, and personal/other activities from 21.5% to 17.1%. There was a paucity of time-motion data. There was great variability in the operational definitions of task categories reported in the studies. Implementation of the ACGME duty hour standards did not have a significant effect on the percentage of time spent in particular tasks. There are conflicting reports on how duty hour changes have affected patient safety. A low proportion of time spent in educational activities deserves further study and may point to a review of the

  17. Milk performance of two cow breeds at two levels of supplementation in long residence time grazing paddocks

    OpenAIRE

    Roca Fernandez, Ana Isabel; González-Rodríguez, Antonio; Leurent, S.; López-Mosquera, M.E.; Gallard, Yves; Delaby, Luc

    2012-01-01

    Milk performance of four groups of cows (H0, H4, N0 and N4) was studied under grazing: two cow breeds, Holstein-Friesian (H) vs. Normande (N), supplemented at pasture with two levels of concentrate, low vs. high (0 and 4 kg cow–1 day–1). A simplified rotational grazing system using three paddocks per rotation with a mean residence time per paddock of 10-days was examined. During this long residence time, maximum milk yield (MY max.) was reached at day 4 followed by a milk yield drop (Dm) at t...

  18. Estimation of sediment residence times in subtropical highland catchments of central Mexico combining river gauging and fallout radionuclides

    Science.gov (United States)

    Evrard, Olivier; Némery, Julien; Gratiot, Nicolas; Duvert, Clément; Lefèvre, Irène; Ayrault, Sophie; Esteves, Michel; Bonté, Philippe

    2010-05-01

    Subtropical regions of the world are affected by intense soil erosion associated with deforestation, overgrazing and cropping intensification. This land degradation leads to important on-site (e.g. decrease in soil fertility) and off-site impacts (e.g. reservoir sedimentation, water pollution). This study determined the mean sediment residence times in soils and rivers of three catchments (3 - 12 km²) with contrasted land uses (i.e. cropland, forests, rangelands, extended gully networks) located in highlands of the transvolcanic belt of central Mexico. Calculations were based on rainfall and river gauging as well as on fallout radionuclide measurements (Be-7, Cs-137, Pb-210). Atmospheric deposition of Be-7 and Pb-210 was estimated based on the analysis of rainfall precipitated samples. Rainfall samples were collected all throughout the rainy season in order to take account of the temporal variations of the radionuclide fluxes. Furthermore, sampling of suspended sediment was conducted at the outlet of each catchment during most of the storms that occurred throughout the 2009 rainy season. Be-7, Cs-137 and Pb-210 concentrations of this sediment were determined by gamma-spectrometry. A two-box balance model was then used to estimate the sediment residence time and the inventory of radionuclides in the three selected catchments. This model subdivided each catchment into two boxes: (i) a "soil-box" characterised by low transport velocities and hence long radionuclide residence times and (ii) a "river-box" covering the river surface and its surroundings characterised by quicker exchanges and shorter radionuclide residence times. Input and output fluxes of sediment and radionuclides were taken into account in each box. Radioactive decay during the residence time of sediment was also considered. The mean residence time of sediment in soils ranged between 13,300 - 28,500 years. In contrast, sediment residence time in rivers was much shorter, fluctuating between 28 and 393

  19. Impact of repository depth on residence times for leaking radionuclides in land-based surface water

    Science.gov (United States)

    Wörman, Anders; Marklund, Lars; Xu, Shulan; Dverstorp, Björn

    2007-03-01

    The multiple scales of landscape topography produce a wide distribution of groundwater circulation cells that control the hydro-geological environments surrounding geological repositories for nuclear waste. The largest circulation cells tend to discharge water into major river reaches, large freshwater systems or the nearby Baltic Sea. We investigated numerically the release of radionuclides from repositories placed in bedrock with depths between 100 to 2000 meters in a Swedish coastal area and found that leakage from the deeper positions emerges primarily in the major aquatic systems. In effect, radionuclides from the deeper repositories are more rapidly transported towards the Sea by the stream system compared to leakage from more shallow repositories. The release from the shallower repositories is significantly retained in the initial stage of the transport in the (superficial) landscape because the discharge occurs in or near low-order streams with high retention characteristics. This retention and residence time for radioactivity in the landscape control radiological doses to biota and can, thus, be expected to constitute an essential part of an associated risk evaluation.

  20. Relationship between fiber degradation and residence time distribution in the processing of long fiber reinforced thermoplastics

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available Long fiber reinforced thermoplastics (LFT were processed by in-line compounding equipment with a modified single screw extruder. A pulse stimulus response technique using PET spheres as the tracer was adopted to obtain residence time distribution (RTD of extrusion compounding. RTD curves were fitted by the model based on the supposition that extrusion compounding was the combination of plug flow and mixed flow. Characteristic parameters of RTD model including P the fraction of plug flow reactor (PFR and d the fraction of dead volume of continuous stirred tank reactor (CSTR were used to associate with fiber degradation presented by fiber length and dispersion. The effects of screw speed, mixing length and channel depth on RTD curves, and characteristic parameters of RTD models as well as their effects on the fiber degradation were investigated. The influence of shear force with different screw speeds and variable channel depth on fiber degradation was studied and the main impetus of fiber degradation was also presented. The optimal process for obtaining the balance of fiber length and dispersion was presented.

  1. Elucidating the Origin of Long Residence Time Binding for Inhibitors of the Metalloprotease Thermolysin.

    Science.gov (United States)

    Cramer, Jonathan; Krimmer, Stefan G; Fridh, Veronica; Wulsdorf, Tobias; Karlsson, Robert; Heine, Andreas; Klebe, Gerhard

    2017-01-20

    Kinetic parameters of protein-ligand interactions are progressively acknowledged as valuable information for rational drug discovery. However, a targeted optimization of binding kinetics is not easy to achieve, and further systematic studies are necessary to increase the understanding about molecular mechanisms involved. We determined association and dissociation rate constants for 17 inhibitors of the metalloprotease thermolysin by surface plasmon resonance spectroscopy and correlated kinetic data with high-resolution crystal structures in complex with the protein. From the structure-kinetics relationship, we conclude that the strength of interaction with Asn112 correlates with the rate-limiting step of dissociation. This residue is located at the beginning of a β-strand motif that lines the binding cleft and is commonly believed to align a substrate for catalysis. A reduced mobility of the Asn112 side chain owing to an enhanced engagement in charge-assisted hydrogen bonds prevents the conformational adjustment associated with ligand release and transformation of the enzyme to its open state. This hypothesis is supported by kinetic data of ZF P LA, a known pseudopeptidic inhibitor of thermolysin, which blocks the conformational transition of Asn112. Interference with this retrograde induced-fit mechanism results in variation of the residence time of thermolysin inhibitors by a factor of 74 000. The high conservation of this structural motif within the M4 and M13 metalloprotease families underpins the importance of this feature and has significant implications for drug discovery.

  2. Subunit Stabilization and Polyethylene Glycolation of Cocaine Esterase Improves In Vivo Residence Time

    Energy Technology Data Exchange (ETDEWEB)

    Narasimhan, Diwahar; Collins, Gregory T.; Nance, Mark R.; Nichols, Joseph; Edwald, Elin; Chan, Jimmy; Ko, Mei-Chuan; Woods, James H.; Tesmer, John J.G.; Sunahara, Roger K. (Michigan)

    2012-03-15

    No small-molecule therapeutic is available to treat cocaine addiction, but enzyme-based therapy to accelerate cocaine hydrolysis in serum has gained momentum. Bacterial cocaine esterase (CocE) is the fastest known native enzyme that hydrolyzes cocaine. However, its lability at 37 C has limited its therapeutic potential. Cross-linking subunits through disulfide bridging is commonly used to stabilize multimeric enzymes. Herein we use structural methods to guide the introduction of two cysteine residues within dimer interface of CocE to facilitate intermolecular disulfide bond formation. The disulfide-crosslinked enzyme displays improved thermostability, particularly when combined with previously described mutations that enhance stability (T172R-G173Q). The newly modified enzyme yielded an extremely stable form of CocE (CCRQ-CocE) that retained greater than 90% of its activity after 41 days at 37 C, representing an improvement of more than 4700-fold over the wild-type enzyme. CCRQ-CocE could also be modified by polyethylene glycol (PEG) polymers, which improved its in vivo residence time from 24 to 72 h, as measured by a cocaine lethality assay, by self-administration in rodents, and by measurement of inhibition of cocaine-induced cardiovascular effects in rhesus monkeys. PEG-CCRQ elicited negligible immune response in rodents. Subunit stabilization and PEGylation has thus produced a potential protein therapeutic with markedly higher stability both in vitro and in vivo.

  3. Optimized Inhibitors of Soluble Epoxide Hydrolase Improve in Vitro Target Residence Time and in Vivo Efficacy

    Science.gov (United States)

    2015-01-01

    Diabetes is affecting the life of millions of people. A large proportion of diabetic patients suffer from severe complications such as neuropathic pain, and current treatments for these complications have deleterious side effects. Thus, alternate therapeutic strategies are needed. Recently, the elevation of epoxy-fatty acids through inhibition of soluble epoxide hydrolase (sEH) was shown to reduce diabetic neuropathic pain in rodents. In this report, we describe a series of newly synthesized sEH inhibitors with at least 5-fold higher potency and doubled residence time inside both the human and rodent sEH enzyme than previously reported inhibitors. These inhibitors also have better physical properties and optimized pharmacokinetic profiles. The optimized inhibitor selected from this new series displayed improved efficacy of almost 10-fold in relieving pain perception in diabetic neuropathic rats as compared to the approved drug, gabapentin, and previously published sEH inhibitors. Therefore, these new sEH inhibitors could be an attractive alternative to treat diabetic neuropathy in humans. PMID:25079952

  4. Relating hyporheic fluxes, residence times, and redox-sensitive biogeochemical processes upstream of beaver dams

    Science.gov (United States)

    Briggs, Martin A.; Lautz, Laura; Hare, Danielle K.

    2013-01-01

    Abstract. Small dams enhance the development of patchy microenvironments along stream corridors by trapping sediment and creating complex streambed morphologies. This patchiness drives intricate hyporheic flux patterns that govern the exchange of O2 and redox-sensitive solutes between the water column and the stream bed. We used multiple tracer techniques, naturally occurring and injected, to evaluate hyporheic flow dynamics and associated biogeochemical cycling and microbial reactivity around 2 beaver dams in Wyoming (USA). High-resolution fiber-optic distributed temperature sensing was used to collect temperature data over 9 vertical streambed profiles and to generate comprehensive vertical flux maps using 1-dimensional (1-D) heat-transport modeling. Coincident with these locations, vertical profiles of hyporheic water were collected every week and analyzed for dissolved O2, pH, dissolved organic C, and several conservative and redox-sensitive solutes. In addition, hyporheic and net stream aerobic microbial reactivity were analyzed with a constant-rate injection of the biologically sensitive resazurin (Raz) smart tracer. The combined results revealed a heterogeneous system with rates of downwelling hyporheic flow organized by morphologic unit and tightly coupled to the redox conditions of the subsurface. Principal component analysis was used to summarize the variability of all redox-sensitive species, and results indicated that hyporheic water varied from oxic-stream-like to anoxic-reduced in direct response to the hydrodynamic conditions and associated residence times. The anaerobic transition threshold predicted by the mean O2 Damko

  5. Drug-target residence time--a case for G protein-coupled receptors.

    Science.gov (United States)

    Guo, Dong; Hillger, Julia M; IJzerman, Adriaan P; Heitman, Laura H

    2014-07-01

    A vast number of marketed drugs act on G protein-coupled receptors (GPCRs), the most successful category of drug targets to date. These drugs usually possess high target affinity and selectivity, and such combined features have been the driving force in the early phases of drug discovery. However, attrition has also been high. Many investigational new drugs eventually fail in clinical trials due to a demonstrated lack of efficacy. A retrospective assessment of successfully launched drugs revealed that their beneficial effects in patients may be attributed to their long drug-target residence times (RTs). Likewise, for some other GPCR drugs short RT could be beneficial to reduce the potential for on-target side effects. Hence, the compounds' kinetics behavior might in fact be the guiding principle to obtain a desired and durable effect in vivo. We therefore propose that drug-target RT should be taken into account as an additional parameter in the lead selection and optimization process. This should ultimately lead to an increased number of candidate drugs moving to the preclinical development phase and on to the market. This review contains examples of the kinetics behavior of GPCR ligands with improved in vivo efficacy and summarizes methods for assessing drug-target RT. © 2014 Wiley Periodicals, Inc.

  6. Investigation of timing effects in modified composite quadrupolar echo pulse sequences by mean of average Hamiltonian theory

    Science.gov (United States)

    Mananga, Eugene Stephane

    2018-01-01

    The utility of the average Hamiltonian theory and its antecedent the Magnus expansion is presented. We assessed the concept of convergence of the Magnus expansion in quadrupolar spectroscopy of spin-1 via the square of the magnitude of the average Hamiltonian. We investigated this approach for two specific modified composite pulse sequences: COM-Im and COM-IVm. It is demonstrated that the size of the square of the magnitude of zero order average Hamiltonian obtained on the appropriated basis is a viable approach to study the convergence of the Magnus expansion. The approach turns to be efficient in studying pulse sequences in general and can be very useful to investigate coherent averaging in the development of high resolution NMR technique in solids. This approach allows comparing theoretically the two modified composite pulse sequences COM-Im and COM-IVm. We also compare theoretically the current modified composite sequences (COM-Im and COM-IVm) to the recently published modified composite pulse sequences (MCOM-I, MCOM-IV, MCOM-I_d, MCOM-IV_d).

  7. Whale shark (Rhincodon typus seasonal presence, residence time and habitat use at darwin island, galapagos marine reserve.

    Directory of Open Access Journals (Sweden)

    David Acuña-Marrero

    Full Text Available The life history of the whale shark (Rhincodon typus, including its reproductive ecology, still remains largely unknown. Here, we present results from the first whale shark population study around Darwin Island, Galapagos Marine Reserve. Following a diversified approach we characterized seasonal occurrence, population structure and size, and described habitat use of whale sharks based on fine scale movements around the island. Whale shark presence at Darwin Island was negatively correlated with Sea Surface Temperature (SST, with highest abundance corresponding to a cool season between July and December over six years of monitoring. From 2011 to 2013 we photo-identified 82 whale sharks ranging from 4 to 13.1 m Total Length (TL. Size distribution was bimodal, with a great majority (91.5% of adult female individuals averaging 11.35 m±0.12 m (TL±SE, all but one showing signs of a potential pregnancy. Population dynamics models for apparently pregnant sharks estimated the presence of 3.76±0.90 (mean ± SE sharks in the study area per day with an individual residence time of 2.09±0.51 (mean ± SE days. Movement patterns analysis of four apparently pregnant individuals tracked with acoustic tags at Darwin Island revealed an intense use of Darwin's Arch, where no feeding or specific behavior has been recorded, together with periodic excursions around the island's vicinity. Sharks showed a preference for intermediate depths (20-30 m with occasional dives mostly to mid-water, remaining the majority of their time at water temperatures between 24-25°C. All of our results point to Darwin Island as an important stopover in a migration, possibly with reproductive purposes, rather than an aggregation site. Current studies carried out in this area to investigate regional scale movement patterns may provide essential information about possible pupping grounds for this enigmatic species.

  8. Whale Shark (Rhincodon typus) Seasonal Presence, Residence Time and Habitat Use at Darwin Island, Galapagos Marine Reserve

    Science.gov (United States)

    Acuña-Marrero, David; Jiménez, Jesús; Smith, Franz; Doherty, Paul F.; Hearn, Alex; Green, Jonathan R.; Paredes-Jarrín, Jules; Salinas-de-León, Pelayo

    2014-01-01

    The life history of the whale shark (Rhincodon typus), including its reproductive ecology, still remains largely unknown. Here, we present results from the first whale shark population study around Darwin Island, Galapagos Marine Reserve. Following a diversified approach we characterized seasonal occurrence, population structure and size, and described habitat use of whale sharks based on fine scale movements around the island. Whale shark presence at Darwin Island was negatively correlated with Sea Surface Temperature (SST), with highest abundance corresponding to a cool season between July and December over six years of monitoring. From 2011 to 2013 we photo-identified 82 whale sharks ranging from 4 to 13.1 m Total Length (TL). Size distribution was bimodal, with a great majority (91.5%) of adult female individuals averaging 11.35 m±0.12 m (TL±SE), all but one showing signs of a potential pregnancy. Population dynamics models for apparently pregnant sharks estimated the presence of 3.76±0.90 (mean ± SE) sharks in the study area per day with an individual residence time of 2.09±0.51 (mean ± SE) days. Movement patterns analysis of four apparently pregnant individuals tracked with acoustic tags at Darwin Island revealed an intense use of Darwin's Arch, where no feeding or specific behavior has been recorded, together with periodic excursions around the island's vicinity. Sharks showed a preference for intermediate depths (20–30 m) with occasional dives mostly to mid-water, remaining the majority of their time at water temperatures between 24–25°C. All of our results point to Darwin Island as an important stopover in a migration, possibly with reproductive purposes, rather than an aggregation site. Current studies carried out in this area to investigate regional scale movement patterns may provide essential information about possible pupping grounds for this enigmatic species. PMID:25551553

  9. Whale shark (Rhincodon typus) seasonal presence, residence time and habitat use at darwin island, galapagos marine reserve.

    Science.gov (United States)

    Acuña-Marrero, David; Jiménez, Jesús; Smith, Franz; Doherty, Paul F; Hearn, Alex; Green, Jonathan R; Paredes-Jarrín, Jules; Salinas-de-León, Pelayo

    2014-01-01

    The life history of the whale shark (Rhincodon typus), including its reproductive ecology, still remains largely unknown. Here, we present results from the first whale shark population study around Darwin Island, Galapagos Marine Reserve. Following a diversified approach we characterized seasonal occurrence, population structure and size, and described habitat use of whale sharks based on fine scale movements around the island. Whale shark presence at Darwin Island was negatively correlated with Sea Surface Temperature (SST), with highest abundance corresponding to a cool season between July and December over six years of monitoring. From 2011 to 2013 we photo-identified 82 whale sharks ranging from 4 to 13.1 m Total Length (TL). Size distribution was bimodal, with a great majority (91.5%) of adult female individuals averaging 11.35 m±0.12 m (TL±SE), all but one showing signs of a potential pregnancy. Population dynamics models for apparently pregnant sharks estimated the presence of 3.76±0.90 (mean ± SE) sharks in the study area per day with an individual residence time of 2.09±0.51 (mean ± SE) days. Movement patterns analysis of four apparently pregnant individuals tracked with acoustic tags at Darwin Island revealed an intense use of Darwin's Arch, where no feeding or specific behavior has been recorded, together with periodic excursions around the island's vicinity. Sharks showed a preference for intermediate depths (20-30 m) with occasional dives mostly to mid-water, remaining the majority of their time at water temperatures between 24-25°C. All of our results point to Darwin Island as an important stopover in a migration, possibly with reproductive purposes, rather than an aggregation site. Current studies carried out in this area to investigate regional scale movement patterns may provide essential information about possible pupping grounds for this enigmatic species.

  10. Alongshore Variation in the Depth of Activation: Implications of Oil Residence Time

    Science.gov (United States)

    Flores, P.; Houser, C.

    2016-12-01

    In 2010 the Deepwater Horizon Oil Spill released approximately 5 million barrels of oil into the Gulf of Mexico just as the nearshore and beach profile were recovering from winter storms. As a consequence, oil mats and tar balls were trapped at depth within the beach and nearshore profile. Excavation of this buried oil during subsequent storms creates the potential for the contamination of adjacent beaches and the degradation of marine ecosystems, which can in turn negatively impact local economies that depend on fisheries and tourism. The potential for oil burial and persistence is dependent on four things: the physio-chemical nature of the oil as it reaches the nearshore environment, the pre-existing morphology of the beach and nearshore, and the evolution of that morphology after the oil is deposited. The depth at which the oil is buried is also dependent on the beach profile during the time of the spill. The purpose of this study is to characterize the alongshore variation in depth of activation on a Deepwater Horizon impacted section of Pensacola Beach, Florida with regards to the implications of oil residence time. Ground- Penetrating Radar (GPR) surveys were conducted along two parallel 1-km transects adjacent to the swash zone and the dune. Additional cross- shore transects were completed every 150 m from the base of the dune to the top of the swash zone. Sediments cores were taken at the crossing points of the alongshore and cross-shore transects, to calibrate the GPR surveys and complete an elemental analysis for the identification of storm layers. The cores were also analyzed for the presence of buried oil.

  11. Temperature sensitivity of soil organic carbon decomposition increased with mean carbon residence time: Field incubation and data assimilation.

    Science.gov (United States)

    Zhou, Xuhui; Xu, Xia; Zhou, Guiyao; Luo, Yiqi

    2018-02-01

    Temperature sensitivity of soil organic carbon (SOC) decomposition is one of the major uncertainties in predicting climate-carbon (C) cycle feedback. Results from previous studies are highly contradictory with old soil C decomposition being more, similarly, or less sensitive to temperature than decomposition of young fractions. The contradictory results are partly from difficulties in distinguishing old from young SOC and their changes over time in the experiments with or without isotopic techniques. In this study, we have conducted a long-term field incubation experiment with deep soil collars (0-70 cm in depth, 10 cm in diameter of PVC tubes) for excluding root C input to examine apparent temperature sensitivity of SOC decomposition under ambient and warming treatments from 2002 to 2008. The data from the experiment were infused into a multi-pool soil C model to estimate intrinsic temperature sensitivity of SOC decomposition and C residence times of three SOC fractions (i.e., active, slow, and passive) using a data assimilation (DA) technique. As active SOC with the short C residence time was progressively depleted in the deep soil collars under both ambient and warming treatments, the residences times of the whole SOC became longer over time. Concomitantly, the estimated apparent and intrinsic temperature sensitivity of SOC decomposition also became gradually higher over time as more than 50% of active SOC was depleted. Thus, the temperature sensitivity of soil C decomposition in deep soil collars was positively correlated with the mean C residence times. However, the regression slope of the temperature sensitivity against the residence time was lower under the warming treatment than under ambient temperature, indicating that other processes also regulated temperature sensitivity of SOC decomposition. These results indicate that old SOC decomposition is more sensitive to temperature than young components, making the old C more vulnerable to future warmer

  12. Importance of powder residence time for the aerosol delivery performance of a commercial dry powder inhaler Aerolizer(®).

    Science.gov (United States)

    Jiang, Liqun; Tang, Yue; Zhang, Hongjiu; Lu, Xifeng; Chen, Xijing; Zhu, Jiabi

    2012-10-01

    The performance of dry powder aerosol delivery systems depends not only on the powder formulation but also on the dry powder inhalers (DPIs). Effects of turbulence, grid, mouthpiece, inlet size, air flow, and capsule on the DPIs performance have been investigated previously. Considering powder dispersion in DPIs is a time-dependent process, the powder residence time in DPIs is supposed to have a great impact on DPIs efficiency. This study sought to investigate the effect of powder residence time on the performance of a commercial DPI Aerolizer(®). A standard Aerolizer(®) (SD) and five modified devices (MD1, MD2, MD3, MD4, and MD5) were employed for this research. Computational fluid dynamics analysis was used to calculate the flow field and the powder residence time in these devices. Recombinant human interleukin-2 inhalation powders and a twin impinger were used for the deposition experiment. The powder mean residence time in the secondary atomization zone of the devices was increased from 0 ms for SD to 0.33, 0.96, 1.42, 1.76, and 2.14 ms for MD1, MD2, MD3, MD4, and MD5, respectively. At a flow rate of 60 L/min, with an increase in the powder residence time in these devices, a significant gradual and increasing trend in the powder respirable fraction was observed from 29.1%± 1.1% (MD1) to 32.6% ± 2.2% (MD2), 37.1% ± 1.1% (MD3), and 43.7% ± 2.1% (MD4). There was no significant difference in the powder respirable fraction between SD and MD1 or between MD4 and MD5. Within a certain range, increasing the powder residence time could improve the performance of Aerolizer(®) by increasing the powder-air interaction time (the main reason) and increasing the powder-device compaction (the secondary reason). Combination of high turbulence level and sufficient powder residence time could further improve the device performance.

  13. MERRA 3D IAU Tendency, Wind Components, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPUDT or tavg3_3d_udt_Cp data product is the MERRA Data Assimilation System 3-Dimensional eastward wind tendencies that is time averaged on pressure levels...

  14. MERRA 3D IAU Diagnostic, Turbulence, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPTRB or tavg3_3d_trb_Cp data product is the MERRA Data Assimilation System 3-Dimensional turbulence diagnostic that is time averaged on pressure levels at a...

  15. MERRA 3D IAU Diagnostic, Cloud Properties, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPCLD or tavg3_3d_cld_Cp data product is the MERRA Data Assimilation System 3-Dimensional cloud diagnostic that is time averaged on pressure levels at a...

  16. MERRA 3D IAU Diagnostic, Moist Physics, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPMST or tavg3_3d_mst_Cp data product is the MERRA Data Assimilation System 3-Dimensional moist process diagnostic that is time averaged on pressure levels...

  17. MERRA 3D IAU Diagnostic, Radiation, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPRAD or tavg3_3d_rad_Cp data product is the MERRA Data Assimilation System 3-Dimensional radiation diagnostic that is time averaged on pressure levels at a...

  18. MERRA 3D IAU Tendency, Temperature, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPTDT or tavg3_3d_tdt_Cp data product is the MERRA Data Assimilation System 3-Dimensional temperature tendencies that is time averaged on pressure levels at...

  19. MERRA 3D IAU Tendency, Specific Humidity, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPQDT or tavg3_3d_qdt_Cp data product is the MERRA Data Assimilation System 3-Dimensional moisture tendencies that is time averaged on pressure levels at a...

  20. MERRA 3D IAU Tendency, Ozone, Time average 3-hourly (1.25x1.25L42) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3CPODT or tavg3_3d_odt_Cp data product is the MERRA Data Assimilation System 3-Dimensional ozone tendencies that is time averaged on pressure levels at a...

  1. MERRA 2D IAU Diagnostic, Surface Fluxes, Time Average 1-hourly (2/3x1/2L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXFLX or tavg1_2d_flx_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface turbulence flux diagnostic that is time averaged...

  2. MERRA 2D IAU Diagnostic, Single Level Meteorology, Time Average 1-hourly (2/3x1/2L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXSLV or tavg1_2d_slv_Nx data product is the MERRA Data Assimilation System 2-Dimensional atmospheric single-level diagnostics that is time averaged...

  3. MERRA Chem 2D IAU Diagnostics, Fluxes and Meteorology, Time Average 3-hourly (surface, 1.25x1L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3FXCHM or tavg3_3d_chm_Fx data product is the MERRA Data Assimilation System Chemistry 2-Dimensional chemistry that is time averaged, single-level, at reduced...

  4. Groundwater residence time and movement in the Maltese islands - A geochemical approach

    Energy Technology Data Exchange (ETDEWEB)

    Stuart, M.E., E-mail: mest@bgs.ac.uk [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Maurice, L. [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Heaton, T.H.E. [British Geological Survey, NERC Isotope Geoscience Laboratory, Keyworth, Nottinghamshire NG12 5GG (United Kingdom); Sapiano, M.; Micallef Sultana, M. [Malta Resources Authority, Marsa MRS 9065 (Malta); Gooddy, D.C.; Chilton, P.J. [British Geological Survey, Wallingford, Oxfordshire OX10 8BB (United Kingdom)

    2010-05-15

    The Maltese islands are composed of two limestone aquifers, the Upper and Lower Coralline Limestone separated by an aquitard, the 'Blue Clay'. The Lower Coralline Limestone is overlain in part by the poorly permeable Globigerina Limestone. The upper perched aquifers are discontinuous and have very limited saturated thickness and a short water level response time to rainfall. Frequent detections of coliforms suggest a rapid route to groundwater. However, the unsaturated zone has a considerable thickness in places and the primary porosity of the Upper Coralline Limestone is high, so there is likely to be older recharge by slow matrix flow as well as rapid recharge from fractures. Measurement of SF{sub 6} from a pumping station in a deep part of one of the perched aquifers indicated a mean saturated zone age of about 15 a. The Main Sea Level aquifers (MSL) on both Malta and Gozo have a large unsaturated thickness as water levels are close to sea level. On Malta, parts of the aquifer are capped by the perched aquifers and more extensively by the Globigerina Limestone. The limited detection of coliform bacteria suggests only some rapid recharge from the surface via fractures or karst features. Transmissivity is low and {sup 3}H and CFC/SF{sub 6} data indicate that saturated zone travel times are in the range 15-40 a. On Gozo the aquifer is similar but is more-extensively capped by impermeable Blue Clay. CFC data show the saturated zone travel time is from 25 a to possibly more than 60 a. Groundwater age is clearly related to the extent of low-permeability cover. The {delta}{sup 13}C signature of groundwater is related to the geochemical processes which occur along the flowpath and is consistent with residence time ages in the sequence; perched aquifers < Malta MSL < Gozo MSL. The {sup 18}O and {sup 2}H enriched isotopic signature of post 1983 desalinated water can be seen in more-modern groundwater, particularly the urbanized areas of the perched and Malta MSL

  5. Fed and fasted gastric pH and gastric residence time in conscious beagle dogs.

    Science.gov (United States)

    Sagawa, Kazuko; Li, Fasheng; Liese, Ryan; Sutton, Steven C

    2009-07-01

    The gastric pH values are controversial in the literature. Some suggest the dog gastric pH is higher than human and dog gastric pH after fed with particular diet is uncertain. Gastric pH in 16 male beagle dogs was measured using Bravo pH telemetry system. For the fed study, the dogs received 10 or 200 g of dog dry food (5L18) 15 min before dosing the Bravo pH capsule, followed by a 50 mL of water to aid in swallowing. It was surprising to find a small, but statistically significantly lower pH in the fed compared to the fasted stomach. The average gastric pH in fasted dogs was 2.05 and 1.08 and 1.26 for 10 and 200 g fed dogs. The average gastric emptying time of the capsule was 1.4, 9.4 and 20 h for fasted, 10 g fed and 200 g fed dogs, respectively. The inter-individual variability was higher in fasted dogs than in fed dogs. The results showed the gastric pH in each colony of dogs can be different from reported values in the literature. It emphasizes that the importance of measuring the pH in each colony when dogs are used to evaluate pharmacokinetics of pH sensitive drugs or formulations.

  6. Recursive Averaging

    Science.gov (United States)

    Smith, Scott G.

    2015-01-01

    In this article, Scott Smith presents an innocent problem (Problem 12 of the May 2001 Calendar from "Mathematics Teacher" ("MT" May 2001, vol. 94, no. 5, p. 384) that was transformed by several timely "what if?" questions into a rewarding investigation of some interesting mathematics. These investigations led to two…

  7. Implementation and evaluation of a simulation curriculum for paediatric residency programs including just-in-time in situ mock codes.

    Science.gov (United States)

    Sam, Jonathan; Pierse, Michael; Al-Qahtani, Abdullah; Cheng, Adam

    2012-02-01

    To develop, implement and evaluate a simulation-based acute care curriculum in a paediatric residency program using an integrated and longitudinal approach. Curriculum framework consisting of three modular, year-specific courses and longitudinal just-in-time, in situ mock codes. Paediatric residency program at BC Children's Hospital, Vancouver, British Columbia. The three year-specific courses focused on the critical first 5 min, complex medical management and crisis resource management, respectively. The just-in-time in situ mock codes simulated the acute deterioration of an existing ward patient, prepared the actual multidisciplinary code team, and primed the surrounding crisis support systems. Each curriculum component was evaluated with surveys using a five-point Likert scale. A total of 40 resident surveys were completed after each of the modular courses, and an additional 28 surveys were completed for the overall simulation curriculum. The highest Likert scores were for hands-on skill stations, immersive simulation environment and crisis resource management teaching. Survey results also suggested that just-in-time mock codes were realistic, reinforced learning, and prepared ward teams for patient deterioration. A simulation-based acute care curriculum was successfully integrated into a paediatric residency program. It provides a model for integrating simulation-based learning into other training programs, as well as a model for any hospital that wishes to improve paediatric resuscitation outcomes using just-in-time in situ mock codes.

  8. Linking granulation performance with residence time and granulation liquid distributions in twin-screw granulation: An experimental investigation

    DEFF Research Database (Denmark)

    Kumar, Ashish; Alakarjula, Maija; Vanhoorne, Valérie

    2016-01-01

    elements in the granulator screw allowing the production of granules with a size distribution appropriate for tableting. The distribution of residence time and granulation liquid is governed by the field conditions (such as location and length of mixing zones) in the twin-screw granulator, thus contain...

  9. The decadal state of the terrestrial carbon cycle : Global retrievals of terrestrial carbon allocation, pools, and residence times

    NARCIS (Netherlands)

    Bloom, A Anthony; Exbrayat, Jean-François; van der Velde, Ivar R; Feng, Liang; Williams, Mathew

    2016-01-01

    The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle

  10. Residence time distribution and hold-up in a cocurrent upflow packed bed reactor at elevated pressure

    NARCIS (Netherlands)

    van Gelder, Klaas B.; Westerterp, K.R.

    1990-01-01

    The residence time distribution in liquid phase was measured in a cocurrent upflow packed bed reactor for the system methanol-hydrogen at low Reynolds numbers and at elevated pressure. The plug flow with axial dispersion model was used to describe mixing in the system. The imperfect pulse method was

  11. Comparison of the tritium residence times of various ceramic breeder materials irradiated in EXOTIC experiments 4 and 5

    International Nuclear Information System (INIS)

    Kwast, H.; Elen, J.D.; Conrad, R.; Casadio, S.; Werle, H.; Verstappen, G.

    1990-09-01

    Tritium residence times have been determined for various ceramic tritium breeding materials from in-situ release measurements. The irradiations, codenamed EXOTIC (EXtraction Of Tritium In Ceramics), were carried out in the High Flux Reactor (HFR) Petten. During the irradiation more than 450 transients were performed and the corresponding tritium release measured. Materials supplied by SCK/CEN (Li 2 ZrO 3 ), CEA (Li 2 ZrO 3 and LiAlO 2 ), ENEA (LiAlO 2 ), KfK (Li 4 SiO 4 ), NRL (Li 6 Zr 2 O 7 ) and ECN (Li 8 ZrO 6 ) were irradiated in EXOTIC-5 to compare the tritium residence times obtained under equal conditions. Apart from differences in density, grain size, pore size and OPV it appeared that the tritium residence times of the lithium zirconates (pellets) were shorter than those of the Li 4 SiO 4 pebbles. The tritium residence times of the Li 4 SiO 4 pebbles were shorter than those of the LiAlO 2 pellets. (author). 7 refs.; 5 figs.; 3 tabs

  12. Hydraulic residence time and iron removal in a wetland receiving ferruginous mine water over a 4 year period from commissioning.

    Science.gov (United States)

    Kusin, F M; Jarvis, A P; Gandy, C J

    2010-01-01

    Analysis of residence time distribution (RTD) has been conducted for the UK Coal Authority's mine water treatment wetland at Lambley, Northumberland, to determine the hydraulic performance of the wetland over a period of approximately 4 years since site commissioning. The wetland RTD was evaluated in accordance with moment analysis and modelled based on a tanks-in-series (TIS) model to yield the hydraulic characteristics of system performance. Greater hydraulic performance was seen during the second site monitoring after 21 months of site operation i.e. longer hydraulic residence time to reflect overall system hydraulic efficiency, compared to wetland performance during its early operation. Further monitoring of residence time during the third year of wetland operation indicated a slight reduction in hydraulic residence time, thus a lower system hydraulic efficiency. In contrast, performance during the fourth year of wetland operation exhibited an improved overall system hydraulic efficiency, suggesting the influence of reed growth over the lifetime of such systems on hydraulic performance. Interestingly, the same pattern was found for iron (which is the primary pollutant of concern in ferruginous mine waters) removal efficiency of the wetland system from the second to fourth year of wetland operation. This may therefore, reflect the maturity of reeds for maintaining efficient flow distribution across the wetland to retain a longer residence time and significant fractions of water involved to enhance the extent of treatment received for iron attenuation. Further monitoring will be conducted to establish whether such performance is maintained, or whether efficiency decreases over time due to accumulation of dead plant material within the wetland cells.

  13. Residence time distributions of artificially infiltrated groundwater used for drinking water production

    Science.gov (United States)

    Popp, A. L.; Marçais, J.; Moeck, C.; Brennwald, M. S.; Kipfer, R.

    2017-12-01

    Public drinking water supply in urban areas is often challenging due to exposure to potential contamination and high water demands. At our study site, a drinking water supply field in Switzerland, managed aquifer recharge (MAR) was implemented to overcome an increasing water demand and decreasing water quality. Water from the river Rhine is put on a system of channels and ponds to artificially infiltrate and hence, increase the natural groundwater availability. The groundwater system consists of two overlying aquifers, with hydraulic connections related to fractures and faults. The deeper aquifer contains contaminants, which possibly originate from nearby landfills and industrial areas. The operating water works aims to pump recently infiltrated water only. However, we suspect that the pumped water contains a fraction of old water due to the fractured zones which serve as hydraulic connection between the two aquifers. With this study, we aim to better understand the mixing patterns between recently infiltrated water and old groundwater to evaluate the risk for contamination of the system. To reach our objective, we used a set of gas tracers (222Rn, 3H/3He, 4He) from fifteen wells distributed throughout the area to estimate the residence time distribution (RTD) of each well. We calibrated the RTD with a Binary Mixing Model, where the fraction of young groundwater is assumed to follow a Piston Flow Model. The older groundwater fraction is calibrated with a Dispersion Model. Our results reflect the heterogeneity of the system with some abstraction wells containing young water only and others showing an admixture of old water which can only be explained by a connection to the deeper aquifer. We also show that our results on calibrated RTDs are in accordance with other geochemical data such as electrical conductivity, major ions and pH. Our results will contribute to a sound conceptual flow and transport understanding and will help to optimize the water supply system.

  14. Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2

    Science.gov (United States)

    Friend, Andrew D.; Lucht, Wolfgang; Rademacher, Tim T.; Keribin, Rozenn; Betts, Richard; Cadule, Patricia; Ciais, Philippe; Clark, Douglas B.; Dankers, Rutger; Falloon, Pete D.; Ito, Akihiko; Kahana, Ron; Kleidon, Axel; Lomas, Mark R.; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Peylin, Philippe; Schaphoff, Sibyll; Vuichard, Nicolas; Warszawski, Lila; Wiltshire, Andy; Woodward, F. Ian

    2014-01-01

    Future climate change and increasing atmospheric CO2 are expected to cause major changes in vegetation structure and function over large fractions of the global land surface. Seven global vegetation models are used to analyze possible responses to future climate simulated by a range of general circulation models run under all four representative concentration pathway scenarios of changing concentrations of greenhouse gases. All 110 simulations predict an increase in global vegetation carbon to 2100, but with substantial variation between vegetation models. For example, at 4 °C of global land surface warming (510–758 ppm of CO2), vegetation carbon increases by 52–477 Pg C (224 Pg C mean), mainly due to CO2 fertilization of photosynthesis. Simulations agree on large regional increases across much of the boreal forest, western Amazonia, central Africa, western China, and southeast Asia, with reductions across southwestern North America, central South America, southern Mediterranean areas, southwestern Africa, and southwestern Australia. Four vegetation models display discontinuities across 4 °C of warming, indicating global thresholds in the balance of positive and negative influences on productivity and biomass. In contrast to previous global vegetation model studies, we emphasize the importance of uncertainties in projected changes in carbon residence times. We find, when all seven models are considered for one representative concentration pathway × general circulation model combination, such uncertainties explain 30% more variation in modeled vegetation carbon change than responses of net primary productivity alone, increasing to 151% for non-HYBRID4 models. A change in research priorities away from production and toward structural dynamics and demographic processes is recommended. PMID:24344265

  15. Firing technology in practice - temperature, residence time, corrosion; Feuerungstechnik in der Praxis - Temperatur, Verweilzeit, Korrosion

    Energy Technology Data Exchange (ETDEWEB)

    Freimann, P.; Holl, D. [Muellheizkraftwerk Betriebsgesellschaft mbH, Burgkirchen/Alz (Germany)

    1998-09-01

    In a circular dated 1st Sept. 1994, i.e., after the issue of the pertinent planning decision, the Federal Environmental Ministry, BMU, laid down uniform standards on measurements and the parameterisation of the evaluation system for different operation states and loads. Subsequently, TUeV, the German Technical Control Board, prepared the parameterisation curves on the basis of these specifications. The implementation of the BMU paper of 1st Sept. 1994 did not result in any advantage, nor did it lead to a reduction of plant emissions, nor to advantages in the operation of the waste-fuelled cogeneration plant. On the contrary, elevated gas consumption and operating trouble due to frequent feed stops worsened the operating state of the plant. Elevated crude gas temperature in the boiler reduced the lifetime of the two boilers to a critical degree. An operating temperature of 850 C and a residence time of approx. 1 sec. in Burgkirchen waste-fuelled cogeneration plant have not worsened emission values while rendering the plant operable again. [Deutsch] Durch Rundschreiben d. BMU vom 01.09.1994 - also nach Erlass des Planfeststellungsbeschlusses - wurden einheitliche Vorgaben ueber Messungen und Parametrierung des Auswertesystems fuer die verschiedenen Betriebs- bzw. Lastzustaende erlassen. Unter Beruecksichtigung dieser Vorgaben wurden vom TUeV die Parametrierungskurven erstellt. Die Umsetzung des BMU-Papieres vom 01.09.1994 ergab keinerlei Vorteile, weder gab es eine Verringerung der anlagenbedingten Emissionen noch Vorteile fuer den Betrieb des MHKW`s. Im Gegenteil, erhoehte Gasverbraeuche und Betriebsstoerungen durch oftmalige Beschickungsstops verschlechterten den Betriebszustand. Erhoehte Rohgastemperatur im Kessel reduzierten die Lebensdauer der beiden Kessel kritisch. Der Betrieb mit 850 C und mit einer Verweilzeit von ca. 1 sec. fuehrt im MHKW Burgkirchen zu keiner Verschlechterung der Emissionswerte, macht aber die Anlagen wieder betreibbar. (orig./SR)

  16. Groundwater residence time and paleohydrology in the Baltic Artesian basin:isotope geochemical data

    Science.gov (United States)

    Vaikmae, R.; Gerber, C.; Purtschert, R.; Aeschbach, W.; Raidla, V., Sr.; Lu, Z. T.; Zappala, J. C.; Mueller, P.; Mokrik, R., Sr.; Jiang, W.

    2016-12-01

    In this study of the Cambrian aquifer system(CAS) in the Baltic Artesian Basin(BAS) (, chemistry, stable isotopes, noble gas measurements, and dating tracers were combined for study the flow and recharge dynamics of the system over the last million years We find that the variability in chemical composition, stable isotopes and noble gas content in the basin is predominately controlled by mixing of three distinct water masses: Holocene and Pleistocene interglacial water, glacial meltwater, and brine. 81Kr is a nearly ideal dating tracer for such old systems. The radiogenic 4He and 40Ar provide additional information, but are more difficult to interpret in terms of groundwater age. In this study, we did not consider diffusive loss of 81Kr to stagnant water, which might result in an overestimation of groundwater ages ). However, the relatively high porosity and large thickness of the CAS, together with the presumed high salinity and low Kr content of the stagnant water all diminish the effect of diffusive 81Kr loss on age estimates. Our results confirm that under normal conditions, underground production of 81Kr is not affecting the dating results. 81Kr, 4He, and 40Ar all indicate a residence time of the brine of more than 1-3 Ma. Some uncertainty about the brine formation process remains, but the combination of chemical and stable isotope composition of the brine, noble gas concentrations and dating results favors evaporative enrichment of seawater. Tracer ages of interglacial water and glacial meltwater are on the order of several hundred thousand years, which means that several reversals of the flow direction in the CAS as a result of the paleoclimatology of the area have to be taken into account. Under such conditions, small vertical leakage, through fracture zones for example, might considerably impact the net flow pattern. Due to the cyclic flow direction reversals, the aquifer was probably in a transient state over most of the last 1 Ma period.

  17. A toolkit for groundwater mean residence time interpretation with gaseous tracers

    Science.gov (United States)

    Dávila, Pablo Fernando; Külls, Christoph; Weiler, Markus

    2013-12-01

    An analytical Excel-based toolkit called Gas-Tracer-Interpretation (GTI) was developed for determining mean residence time (MRT) of groundwater samples and for validating conceptual model assumptions. This novel data interpretation toolkit improves data handling during analysis and resolves some problems in the interpretation of data from environmental tracers. The toolkit can assist error detection, uncertainty and ambiguity during data analysis, particularly ambiguity due to the decline in atmospheric data of CFC input functions (air-mixing ratios of tracers). The innovative interpretation methodologies are: (1) corrections of environmental tracer data are conducted in concentrations in water instead of air (atmosphere), allowing comparison of different tracer input functions under similar conditions and thereby replacing the use of unique global atmospheric data; (2) a multi-model, multi-tracer approach is adopted to improve the number of different combinations of environmental tracers and lumped-parameter models (piston flow (PM), exponential (EM), exponential-piston flow (EPM), advection-dispersion (DM) and gamma (GM)); and (3) generation of sufficient information for determination of erroneous, unclear and ambiguous outcomes. Results are linked to graphical analysis to improve data view. GTI supports the environmental tracers CFC-11, CFC-12, CFC-113, SF6, 3H, and also SF5CF3, which is included as it represents a promising environmental tracer in hydrological research. The toolkit compares modeled input functions of tracers and data from samples. The apparent recharge age and MRT are estimated by combining explicit graphical and numerical data presentation. Due to the multi-model approach, it is possible to contrast selected models and estimate the best fit for a given sample, which is particularly useful for validating conceptual model assumptions. The toolkit has been developed in Microsoft ®Excel, and hence is user-friendly such that advanced programming

  18. Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2.

    Science.gov (United States)

    Friend, Andrew D; Lucht, Wolfgang; Rademacher, Tim T; Keribin, Rozenn; Betts, Richard; Cadule, Patricia; Ciais, Philippe; Clark, Douglas B; Dankers, Rutger; Falloon, Pete D; Ito, Akihiko; Kahana, Ron; Kleidon, Axel; Lomas, Mark R; Nishina, Kazuya; Ostberg, Sebastian; Pavlick, Ryan; Peylin, Philippe; Schaphoff, Sibyll; Vuichard, Nicolas; Warszawski, Lila; Wiltshire, Andy; Woodward, F Ian

    2014-03-04

    Future climate change and increasing atmospheric CO2 are expected to cause major changes in vegetation structure and function over large fractions of the global land surface. Seven global vegetation models are used to analyze possible responses to future climate simulated by a range of general circulation models run under all four representative concentration pathway scenarios of changing concentrations of greenhouse gases. All 110 simulations predict an increase in global vegetation carbon to 2100, but with substantial variation between vegetation models. For example, at 4 °C of global land surface warming (510-758 ppm of CO2), vegetation carbon increases by 52-477 Pg C (224 Pg C mean), mainly due to CO2 fertilization of photosynthesis. Simulations agree on large regional increases across much of the boreal forest, western Amazonia, central Africa, western China, and southeast Asia, with reductions across southwestern North America, central South America, southern Mediterranean areas, southwestern Africa, and southwestern Australia. Four vegetation models display discontinuities across 4 °C of warming, indicating global thresholds in the balance of positive and negative influences on productivity and biomass. In contrast to previous global vegetation model studies, we emphasize the importance of uncertainties in projected changes in carbon residence times. We find, when all seven models are considered for one representative concentration pathway × general circulation model combination, such uncertainties explain 30% more variation in modeled vegetation carbon change than responses of net primary productivity alone, increasing to 151% for non-HYBRID4 models. A change in research priorities away from production and toward structural dynamics and demographic processes is recommended.

  19. Improving residents' handovers through just-in-time training for structured communication.

    Science.gov (United States)

    Rourke, Liam; Amin, Aditi; Boyington, Curtiss; Ao, Peter; Frolova, Natalia

    2016-01-01

    In a recent quality assurance project we learned that nearly half of the handovers we examined were characterized as unsatisfactory by our residents, who provided examples in which their anxiety had been piqued and patient care had been affected. These reports substantiated a growing body of literature on the relationship between the quality of handover and the quality of patient care, so we sought to improve the quality and consistency of the in-hosptial handovers undertaken by our internal medicine residents. Senior residents attended morning report for three consecutive month long blocks and evaluated the quality of the handovers using an observational protocol comprised of 16 aspects of effective handover. During the first block, the resident observed a median of eight of the 16 practices occurring across the 46 handovers, and a large amount of variability. At the beginning of the subsequent block we presented a concise introduction to a structured handover procedure (SBARR). The median quality of the subsequent 33 handovers rose to 11, and the variability decreased considerably. In the next block we refined the SBARR orientation to focus on the errors observed in the previous blocks, and the improvement in the quality and variability was sustained. The minor change, which requires few resources to sustain, had a favourable impact on the quality of our residents' in-hospital handovers.

  20. Mapping axonal density and average diameter using non-monotonic time-dependent gradient-echo MRI

    DEFF Research Database (Denmark)

    Nunes, Daniel; Cruz, Tomás L; Jespersen, Sune N

    2017-01-01

    Abstract White Matter (WM) microstructures, such as axonal density and average diameter, are crucial to the normal function of the Central Nervous System (CNS) as they are closely related with axonal conduction velocities. Conversely, disruptions of these microstructural features may result......, the axonal density can be extracted. We then experimentally demonstrate that maps derived from MGE acquired at 16.4 T in ex-vivo spinal cords, where the different tracts characterized by different microstructures are clearly contrasted in parametric maps extracted by fitting the MGE decay to the model. When...

  1. Structure-kinetic relationship studies of cannabinoid CB2receptor agonists reveal substituent-specific lipophilic effects on residence time.

    Science.gov (United States)

    Soethoudt, Marjolein; Hoorens, Mark W H; Doelman, Ward; Martella, Andrea; van der Stelt, Mario; Heitman, Laura H

    2018-03-21

    A decade ago, the drug-target residence time model has been (re-)introduced, which describes the importance of binding kinetics of ligands on their protein targets. Since then, it has been applied successfully for multiple protein targets, including GPCRs, for the development of lead compounds with slow dissociation kinetics (i.e. long target residence time) to increase in vivo efficacy or with short residence time to prevent on-target associated side effects. To date, this model has not been applied in the design and pharmacological evaluation of novel selective ligands for the cannabinoid CB 2 receptor (CB 2 R), a GPCR with therapeutic potential in the treatment of tissue injury and inflammatory diseases. Here, we have investigated the relationships between physicochemical properties, binding kinetics and functional activity in two different signal transduction pathways, G protein activation and β-arrestin recruitment. We synthesized 24 analogues of 3-cyclopropyl-1-(4-(6-((1,1-dioxidothiomorpholino)methyl)-5-fluoropyridin-2-yl)benzyl)imidazoleidine-2,4-dione (LEI101), our previously reported in vivo active and CB 2 R-selective agonist, with varying basicity and lipophilicity. We identified a positive correlation between target residence time and functional potency due to an increase in lipophilicity on the alkyl substituents, which was not the case for the amine substituents. Basicity of the agonists did not show a relationship with affinity, residence time or functional activity. Our findings provide important insights about the effects of physicochemical properties of the specific substituents of this scaffold on the binding kinetics of agonists and their CB 2 R pharmacology. This work therefore shows how CB 2 R agonists can be designed to have optimal kinetic profiles, which could aid the lead optimization process in drug discovery for the study or treatment of inflammatory diseases. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights

  2. The Target Residence Time of Antihistamines Determines Their Antagonism of the G Protein-Coupled Histamine H1 Receptor

    Directory of Open Access Journals (Sweden)

    Reggie Bosma

    2017-09-01

    Full Text Available The pharmacodynamics of drug-candidates is often optimized by metrics that describe target binding (Kd or Ki value or target modulation (IC50. However, these metrics are determined at equilibrium conditions, and consequently information regarding the onset and offset of target engagement and modulation is lost. Drug-target residence time is a measure for the lifetime of the drug-target complex, which has recently been receiving considerable interest, as target residence time is shown to have prognostic value for the in vivo efficacy of several drugs. In this study, we have investigated the relation between the increased residence time of antihistamines at the histamine H1 receptor (H1R and the duration of effective target-inhibition by these antagonists. Hela cells, endogenously expressing low levels of the H1R, were incubated with a series of antihistamines and dissociation was initiated by washing away the unbound antihistamines. Using a calcium-sensitive fluorescent dye and a label free, dynamic mass redistribution based assay, functional recovery of the H1R responsiveness was measured by stimulating the cells with histamine over time, and the recovery was quantified as the receptor recovery time. Using these assays, we determined that the receptor recovery time for a set of antihistamines differed more than 40-fold and was highly correlated to their H1R residence times, as determined with competitive radioligand binding experiments to the H1R in a cell homogenate. Thus, the receptor recovery time is proposed as a cell-based and physiologically relevant metric for the lead optimization of G protein-coupled receptor antagonists, like the H1R antagonists. Both, label-free or real-time, classical signaling assays allow an efficient and physiologically relevant determination of kinetic properties of drug molecules.

  3. The Target Residence Time of Antihistamines Determines Their Antagonism of the G Protein-Coupled Histamine H1 Receptor

    Science.gov (United States)

    Bosma, Reggie; Witt, Gesa; Vaas, Lea A. I.; Josimovic, Ivana; Gribbon, Philip; Vischer, Henry F.; Gul, Sheraz; Leurs, Rob

    2017-01-01

    The pharmacodynamics of drug-candidates is often optimized by metrics that describe target binding (Kd or Ki value) or target modulation (IC50). However, these metrics are determined at equilibrium conditions, and consequently information regarding the onset and offset of target engagement and modulation is lost. Drug-target residence time is a measure for the lifetime of the drug-target complex, which has recently been receiving considerable interest, as target residence time is shown to have prognostic value for the in vivo efficacy of several drugs. In this study, we have investigated the relation between the increased residence time of antihistamines at the histamine H1 receptor (H1R) and the duration of effective target-inhibition by these antagonists. Hela cells, endogenously expressing low levels of the H1R, were incubated with a series of antihistamines and dissociation was initiated by washing away the unbound antihistamines. Using a calcium-sensitive fluorescent dye and a label free, dynamic mass redistribution based assay, functional recovery of the H1R responsiveness was measured by stimulating the cells with histamine over time, and the recovery was quantified as the receptor recovery time. Using these assays, we determined that the receptor recovery time for a set of antihistamines differed more than 40-fold and was highly correlated to their H1R residence times, as determined with competitive radioligand binding experiments to the H1R in a cell homogenate. Thus, the receptor recovery time is proposed as a cell-based and physiologically relevant metric for the lead optimization of G protein-coupled receptor antagonists, like the H1R antagonists. Both, label-free or real-time, classical signaling assays allow an efficient and physiologically relevant determination of kinetic properties of drug molecules. PMID:29033838

  4. The Target Residence Time of Antihistamines Determines Their Antagonism of the G Protein-Coupled Histamine H1 Receptor.

    Science.gov (United States)

    Bosma, Reggie; Witt, Gesa; Vaas, Lea A I; Josimovic, Ivana; Gribbon, Philip; Vischer, Henry F; Gul, Sheraz; Leurs, Rob

    2017-01-01

    The pharmacodynamics of drug-candidates is often optimized by metrics that describe target binding (K d or K i value) or target modulation (IC 50 ). However, these metrics are determined at equilibrium conditions, and consequently information regarding the onset and offset of target engagement and modulation is lost. Drug-target residence time is a measure for the lifetime of the drug-target complex, which has recently been receiving considerable interest, as target residence time is shown to have prognostic value for the in vivo efficacy of several drugs. In this study, we have investigated the relation between the increased residence time of antihistamines at the histamine H 1 receptor (H 1 R) and the duration of effective target-inhibition by these antagonists. Hela cells, endogenously expressing low levels of the H 1 R, were incubated with a series of antihistamines and dissociation was initiated by washing away the unbound antihistamines. Using a calcium-sensitive fluorescent dye and a label free, dynamic mass redistribution based assay, functional recovery of the H 1 R responsiveness was measured by stimulating the cells with histamine over time, and the recovery was quantified as the receptor recovery time . Using these assays, we determined that the receptor recovery time for a set of antihistamines differed more than 40-fold and was highly correlated to their H 1 R residence times, as determined with competitive radioligand binding experiments to the H 1 R in a cell homogenate. Thus, the receptor recovery time is proposed as a cell-based and physiologically relevant metric for the lead optimization of G protein-coupled receptor antagonists, like the H 1 R antagonists. Both, label-free or real-time, classical signaling assays allow an efficient and physiologically relevant determination of kinetic properties of drug molecules.

  5. Estimation of gastric residence time of the Heidelberg capsule in humans: effect of varying food composition

    International Nuclear Information System (INIS)

    Mojaverian, P.; Ferguson, R.K.; Vlasses, P.H.; Rocci, M.L. Jr.; Oren, A.; Fix, J.A.; Caldwell, L.J.; Gardner, C.

    1985-01-01

    In animal and human studies, the gastric emptying of large (greater than 1 mm) indigestible solids is due to the activity of the interdigestive migrating myoelectric complex. The gastric residence time (GRT) of an orally administered, nondigestible, pH-sensitive, radiotelemetric device (Heidelberg capsule) was evaluated in three studies in healthy volunteers. In 6 subjects, the GRT of the Heidelberg capsule was compared with the half-emptying time (t1/2) of diethylenetriaminepentaacetic acid labeled with technetium 99m after a 4-ml/kg liquid fatty meal. The mean (+/-SD) GRT (4.3 +/- 1.4 h) was significantly (p less than 0.001) longer than the mean t1/2 (1.1 +/- 0.3 h); the GRT was prolonged compared with the t1/2 in each subject. In a randomized, crossover trial in 10 subjects, frequent feeding caused a dramatic prolongation in mean GRT of the capsule compared with the fasting state (greater than 14.5 vs. 0.5 h, p less than 0.005). In another crossover study in 6 subjects, the GRT of the capsule was evaluated after an overnight fast, a standard breakfast including solid food, and a liquid meal (i.e., 200 ml of diluted light cream). The mean GRT was 2.6 +/- 0.9 h after the liquid meal vs. 1.2 +/- 0.8 h after fasting (p less than 0.025). The mean GRT after the breakfast was 4.8 +/- 1.5 h, which was significantly greater than that after fasting (p less than 0.001) and after the liquid meal (p less than 0.01). These data suggest that the GRT of the Heidelberg capsule is a marker of the interdigestive migrating myoelectric complex in humans, the interdigestive migrating myoelectric complex can be markedly delayed by frequent feedings with solids, and the interdigestive migrating myoelectric complex is delayed by both liquid and solid meals

  6. Estimation of gastric residence time of the Heidelberg capsule in humans: effect of varying food composition

    Energy Technology Data Exchange (ETDEWEB)

    Mojaverian, P.; Ferguson, R.K.; Vlasses, P.H.; Rocci, M.L. Jr.; Oren, A.; Fix, J.A.; Caldwell, L.J.; Gardner, C.

    1985-08-01

    In animal and human studies, the gastric emptying of large (greater than 1 mm) indigestible solids is due to the activity of the interdigestive migrating myoelectric complex. The gastric residence time (GRT) of an orally administered, nondigestible, pH-sensitive, radiotelemetric device (Heidelberg capsule) was evaluated in three studies in healthy volunteers. In 6 subjects, the GRT of the Heidelberg capsule was compared with the half-emptying time (t1/2) of diethylenetriaminepentaacetic acid labeled with technetium 99m after a 4-ml/kg liquid fatty meal. The mean (+/-SD) GRT (4.3 +/- 1.4 h) was significantly (p less than 0.001) longer than the mean t1/2 (1.1 +/- 0.3 h); the GRT was prolonged compared with the t1/2 in each subject. In a randomized, crossover trial in 10 subjects, frequent feeding caused a dramatic prolongation in mean GRT of the capsule compared with the fasting state (greater than 14.5 vs. 0.5 h, p less than 0.005). In another crossover study in 6 subjects, the GRT of the capsule was evaluated after an overnight fast, a standard breakfast including solid food, and a liquid meal (i.e., 200 ml of diluted light cream). The mean GRT was 2.6 +/- 0.9 h after the liquid meal vs. 1.2 +/- 0.8 h after fasting (p less than 0.025). The mean GRT after the breakfast was 4.8 +/- 1.5 h, which was significantly greater than that after fasting (p less than 0.001) and after the liquid meal (p less than 0.01). These data suggest that the GRT of the Heidelberg capsule is a marker of the interdigestive migrating myoelectric complex in humans, the interdigestive migrating myoelectric complex can be markedly delayed by frequent feedings with solids, and the interdigestive migrating myoelectric complex is delayed by both liquid and solid meals.

  7. Linking granulation performance with residence time and granulation liquid distributions in twin-screw granulation: An experimental investigation.

    Science.gov (United States)

    Kumar, Ashish; Alakarjula, Maija; Vanhoorne, Valérie; Toiviainen, Maunu; De Leersnyder, Fien; Vercruysse, Jurgen; Juuti, Mikko; Ketolainen, Jarkko; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar

    2016-07-30

    Twin-screw granulation is a promising wet granulation technique for the continuous manufacturing of pharmaceutical solid dosage forms. A twin screw granulator displays a short residence time. Thus, the solid-liquid mixing must be achieved quickly by appropriate arrangement of transport and kneading elements in the granulator screw allowing the production of granules with a size distribution appropriate for tableting. The distribution of residence time and granulation liquid is governed by the field conditions (such as location and length of mixing zones) in the twin-screw granulator, thus contain interesting information on granulation time, mixing and resulting sub-processes such as wetting, aggregation and breakage. In this study, the impact of process (feed rate, screw speed and liquid-to-solid ratio) and equipment parameters (number of kneading discs and stagger angle) on the residence time (distribution), the granulation liquid-powder mixing and the resulting granule size distributions during twin-screw granulation were investigated. Residence time and axial mixing data was extracted from tracer maps and the solid-liquid mixing was quantified from moisture maps, obtained by monitoring the granules at the granulator outlet using near infra-red chemical imaging (NIR-CI). The granule size distribution was measured using the sieving method. An increasing screw speed dominantly reduced the mean residence time. Interaction of material throughput with the screw speed and with the number of kneading discs led to most variation in the studied responses including residence time and mixing capacity. At a high screw speed, granulation yield improved due to high axial mixing. However, increasing material throughput quickly lowers the yield due to insufficient mixing of liquid and powder. Moreover, increasing liquid-to-solid ratio resulted in more oversized granules, and the fraction of oversized granules further increased at higher throughput. Although an increasing number

  8. Neural networks prediction and fault diagnosis applied to stationary and non stationary ARMA (Autoregressive moving average) modeled time series

    International Nuclear Information System (INIS)

    Marseguerra, M.; Minoggio, S.; Rossi, A.; Zio, E.

    1992-01-01

    The correlated noise affecting many industrial plants under stationary or cyclo-stationary conditions - nuclear reactors included -has been successfully modeled by autoregressive moving average (ARMA) due to the versatility of this technique. The relatively recent neural network methods have similar features and much effort is being devoted to exploring their usefulness in forecasting and control. Identifying a signal by means of an ARMA model gives rise to the problem of selecting its correct order. Similar difficulties must be faced when applying neural network methods and, specifically, particular care must be given to the setting up of the appropriate network topology, the data normalization procedure and the learning code. In the present paper the capability of some neural networks of learning ARMA and seasonal ARMA processes is investigated. The results of the tested cases look promising since they indicate that the neural networks learn the underlying process with relative ease so that their forecasting capability may represent a convenient fault diagnosis tool. (Author)

  9. Chemical composition profiles during alkaline flooding at different temperatures and extended residence times

    Energy Technology Data Exchange (ETDEWEB)

    Aflaki, R.; Handy, L.L.

    1992-12-01

    The objective of this work was to investigate whether or not caustic sweeps the major portion of the reservoir efficiently during an alkaline flood process. It was also the objective of this work to study the state of final equilibrium during a caustic flood through determination of the pH and chemical composition profiles along the porous medium. For this purpose, a long porous medium which provided extended residence times was required. It was necessary to set up the porous medium such that the changes in the pH and chemical composition of the solution could be monitored. Four Berea sandstone cores (8 in. length and1 in. diameter) placed in series provided the desired length and the opportunity for sampling in-between cores. This enabled establishment of pH and chemical composition profiles. The experiments were run at, temperatures up.to 180{degrees}C, and the flow rates varied from 4.8 to 0.2 ft/day. The samples were analyzed for pH and for Si and Al concentrations.The results show that caustic consumption is insignificant for temperatures up to 100{degrees}C. Above 100{degrees}C consumption increases and is accompanied by a significant decrease in pH. The sharp decline in pH also coincides with a sharp decline in concentration of silica in solution. The results also show that alumina is removed from the solution and solubility of alumina ultimately reaches zero. Sharp silica and pH declines take place even in the absence of any alumina in solution. As a result, removal of silica from solution is attributed to the irreversible caustic/rock interaction. This interaction is in the form of chemisorption reactions in which silica is adsorbed onto the rock surface consuming hydroxyl ion. Once these reactions were satisfied, caustic breakthrough occurs at a high pH. However, significant pore volumes of caustic must be injected for completion of the chemisorption.

  10. Chemical composition profiles during alkaline flooding at different temperatures and extended residence times

    Energy Technology Data Exchange (ETDEWEB)

    Aflaki, R.; Handy, L.L.

    1992-12-01

    The objective of this work was to investigate whether or not caustic sweeps the major portion of the reservoir efficiently during an alkaline flood process. It was also the objective of this work to study the state of final equilibrium during a caustic flood through determination of the pH and chemical composition profiles along the porous medium. For this purpose, a long porous medium which provided extended residence times was required. It was necessary to set up the porous medium such that the changes in the pH and chemical composition of the solution could be monitored. Four Berea sandstone cores (8 in. length and1 in. diameter) placed in series provided the desired length and the opportunity for sampling in-between cores. This enabled establishment of pH and chemical composition profiles. The experiments were run at, temperatures up.to 180[degrees]C, and the flow rates varied from 4.8 to 0.2 ft/day. The samples were analyzed for pH and for Si and Al concentrations.The results show that caustic consumption is insignificant for temperatures up to 100[degrees]C. Above 100[degrees]C consumption increases and is accompanied by a significant decrease in pH. The sharp decline in pH also coincides with a sharp decline in concentration of silica in solution. The results also show that alumina is removed from the solution and solubility of alumina ultimately reaches zero. Sharp silica and pH declines take place even in the absence of any alumina in solution. As a result, removal of silica from solution is attributed to the irreversible caustic/rock interaction. This interaction is in the form of chemisorption reactions in which silica is adsorbed onto the rock surface consuming hydroxyl ion. Once these reactions were satisfied, caustic breakthrough occurs at a high pH. However, significant pore volumes of caustic must be injected for completion of the chemisorption.

  11. A space variant maximum average correlation height (MACH) filter for object recognition in real time thermal images for security applications

    Science.gov (United States)

    Gardezi, Akber; Alkandri, Ahmed; Birch, Philip; Young, Rupert; Chatwin, Chris

    2010-10-01

    We propose a space variant Maximum Average Correlation Height (MACH) filter which can be locally modified depending upon its position in the input frame. This can be used to detect targets in an environment from varying ranges and in unpredictable weather conditions using thermal images. It enables adaptation of the filter dependant on background heat signature variances and also enables the normalization of the filter energy levels. The kernel can be normalized to remove a non-uniform brightness distribution if this occurs in different regions of the image. The main constraint in this implementation is the dependence on computational ability of the system. This can be minimized with the recent advances in optical correlators using scanning holographic memory, as proposed by Birch et al. [1] In this paper we describe the discrimination abilities of the MACH filter against background heat signature variances and tolerance to changes in scale and calculate the improvement in detection capabilities with the introduction of a nonlinearity. We propose a security detection system which exhibits a joint process where human and an automated pattern recognition system contribute to the overall solution for the detection of pre-defined targets.

  12. Average first-passage time of a quasi-Hamiltonian Mathieu oscillator with parametric and forcing excitations

    Science.gov (United States)

    Vanvinckenroye, H.; Denoёl, V.

    2017-10-01

    A linear oscillator simultaneously subjected to stochastic forcing and parametric excitation is considered. The time required for this system to evolve from a low initial energy level until a higher energy state for the first time is a random variable. Its expectation satisfies the Pontryagin equation of the problem, which is solved with the asymptotic expansion method developed by Khasminskii. This allowed deriving closed-form expressions for the expected first passage time. A comprehensive parameter analysis of these solutions is performed. Beside identifying the important dimensionless groups governing the problem, it also highlights three important regimes which are called incubation, multiplicative and additive because of their specific features. Those three regimes are discussed with the parameters of the problem.

  13. Fast Pyrolysis Behavior of Banagrass as a Function of Temperature and Volatiles Residence Time in a Fluidized Bed Reactor.

    Science.gov (United States)

    Morgan, Trevor James; Turn, Scott Q; George, Anthe

    2015-01-01

    A reactor was designed and commissioned to study the fast pyrolysis behavior of banagrass as a function of temperature and volatiles residence time. Four temperatures between 400 and 600°C were examined as well as four residence times between ~1.0 and 10 seconds. Pyrolysis product distributions of bio-oil, char and permanent gases were determined at each reaction condition. The elemental composition of the bio-oils and chars was also assessed. The greatest bio-oil yield was recorded when working at 450°C with a volatiles residence time of 1.4 s, ~37 wt% relative to the dry ash free feedstock (excluding pyrolysis water). The amounts of char (organic fraction) and permanent gases under these conditions are ~4 wt% and 8 wt% respectively. The bio-oil yield stated above is for 'dry' bio-oil after rotary evaporation to remove solvent, which results in volatiles and pyrolysis water being removed from the bio-oil. The material removed during drying accounts for the remainder of the pyrolysis products. The 'dry' bio-oil produced under these conditions contains ~56 wt% carbon which is ~40 wt% of the carbon present in the feedstock. The oxygen content of the 450°C, 1.4 s 'dry' bio-oil is ~38 wt%, which accounts for ~33 wt% of the oxygen in the feedstock. At higher temperature or longer residence time less bio-oil and char is recovered and more gas and light volatiles are produced. Increasing the temperature has a more significant effect on product yields and composition than increasing the volatiles residence time. At 600°C and a volatiles residence time of 1.2 seconds the bio-oil yield is ~21 wt% of the daf feedstock, with a carbon content of 64 wt% of the bio-oil. The bio-oil yield from banagrass is significantly lower than from woody biomass or grasses such as switchgrass or miscanthus, but is similar to barley straw. The reason for the low bio-oil yield from banagrass is thought to be related to its high ash content (8.5 wt% dry basis) and high concentration of alkali

  14. Fast Pyrolysis Behavior of Banagrass as a Function of Temperature and Volatiles Residence Time in a Fluidized Bed Reactor.

    Directory of Open Access Journals (Sweden)

    Trevor James Morgan

    Full Text Available A reactor was designed and commissioned to study the fast pyrolysis behavior of banagrass as a function of temperature and volatiles residence time. Four temperatures between 400 and 600°C were examined as well as four residence times between ~1.0 and 10 seconds. Pyrolysis product distributions of bio-oil, char and permanent gases were determined at each reaction condition. The elemental composition of the bio-oils and chars was also assessed. The greatest bio-oil yield was recorded when working at 450°C with a volatiles residence time of 1.4 s, ~37 wt% relative to the dry ash free feedstock (excluding pyrolysis water. The amounts of char (organic fraction and permanent gases under these conditions are ~4 wt% and 8 wt% respectively. The bio-oil yield stated above is for 'dry' bio-oil after rotary evaporation to remove solvent, which results in volatiles and pyrolysis water being removed from the bio-oil. The material removed during drying accounts for the remainder of the pyrolysis products. The 'dry' bio-oil produced under these conditions contains ~56 wt% carbon which is ~40 wt% of the carbon present in the feedstock. The oxygen content of the 450°C, 1.4 s 'dry' bio-oil is ~38 wt%, which accounts for ~33 wt% of the oxygen in the feedstock. At higher temperature or longer residence time less bio-oil and char is recovered and more gas and light volatiles are produced. Increasing the temperature has a more significant effect on product yields and composition than increasing the volatiles residence time. At 600°C and a volatiles residence time of 1.2 seconds the bio-oil yield is ~21 wt% of the daf feedstock, with a carbon content of 64 wt% of the bio-oil. The bio-oil yield from banagrass is significantly lower than from woody biomass or grasses such as switchgrass or miscanthus, but is similar to barley straw. The reason for the low bio-oil yield from banagrass is thought to be related to its high ash content (8.5 wt% dry basis and high

  15. Fast Pyrolysis Behavior of Banagrass as a Function of Temperature and Volatiles Residence Time in a Fluidized Bed Reactor

    Science.gov (United States)

    Morgan, Trevor James; Turn, Scott Q.; George, Anthe

    2015-01-01

    A reactor was designed and commissioned to study the fast pyrolysis behavior of banagrass as a function of temperature and volatiles residence time. Four temperatures between 400 and 600°C were examined as well as four residence times between ~1.0 and 10 seconds. Pyrolysis product distributions of bio-oil, char and permanent gases were determined at each reaction condition. The elemental composition of the bio-oils and chars was also assessed. The greatest bio-oil yield was recorded when working at 450°C with a volatiles residence time of 1.4 s, ~37 wt% relative to the dry ash free feedstock (excluding pyrolysis water). The amounts of char (organic fraction) and permanent gases under these conditions are ~4 wt% and 8 wt% respectively. The bio-oil yield stated above is for 'dry' bio-oil after rotary evaporation to remove solvent, which results in volatiles and pyrolysis water being removed from the bio-oil. The material removed during drying accounts for the remainder of the pyrolysis products. The 'dry' bio-oil produced under these conditions contains ~56 wt% carbon which is ~40 wt% of the carbon present in the feedstock. The oxygen content of the 450°C, 1.4 s 'dry' bio-oil is ~38 wt%, which accounts for ~33 wt% of the oxygen in the feedstock. At higher temperature or longer residence time less bio-oil and char is recovered and more gas and light volatiles are produced. Increasing the temperature has a more significant effect on product yields and composition than increasing the volatiles residence time. At 600°C and a volatiles residence time of 1.2 seconds the bio-oil yield is ~21 wt% of the daf feedstock, with a carbon content of 64 wt% of the bio-oil. The bio-oil yield from banagrass is significantly lower than from woody biomass or grasses such as switchgrass or miscanthus, but is similar to barley straw. The reason for the low bio-oil yield from banagrass is thought to be related to its high ash content (8.5 wt% dry basis) and high concentration of alkali

  16. Time-motion studies of internal medicine residents' duty hours: a systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Leafloor CW

    2015-11-01

    Full Text Available Cameron W Leafloor,1 Heather A Lochnan,2,3,6 Catherine Code,2,4 Erin J Keely,2,3,6 Deanna M Rothwell,5,6 Alan J Forster,2,4–6 Allen R Huang2,6,7 1Faculty of Medicine, 2Department of Medicine, 3Division of Endocrinology and Metabolism, 4Division of General Internal Medicine, 5Performance Measurement and Innovation, 6Ottawa Hospital Research Institute, 7Division of Geriatric Medicine, The Ottawa Hospital and University of Ottawa, Ottawa, ON, Canada Background: Since the mid-1980s, medical residents' long duty hours have been under scrutiny as a factor affecting patient safety and the work environment for the residents. After several mandated changes in duty hours, it is important to understand how residents spend their time before proposing and implementing future changes. Time-motion methodology may provide reliable information on what residents do while on duty.Purpose: The purpose of this study is to review all available literature pertaining to time-motion studies of internal medicine residents while on a medicine service and to understand how much of their time is apportioned to various categories of tasks, and also to determine the effects of the Accreditation Council for Graduate Medical Education (ACGME-mandated duty hour changes on resident workflow in North America.Methods: Electronic bibliographic databases were searched for articles in English between 1941 and April 2013 reporting time-motion studies of internal medicine residents rotating through a general medicine service.Results: Eight articles were included. Residents spent 41.8% of time in patient care activities, 18.1% communicating, 13.8% in educational activities, 19.7% in personal/other, and 6.6% in transit. North American data showed the following changes after the implementation of the ACGME 2003 duty hours standard: patient care activities from 41.8% to 40.8%, communication activities from 19.0% to 22.3%, educational activities from 17.7% to 11.6%, and personal

  17. On the applicability of short time measurements to the determination of annual average of radon concentration in dwelling

    International Nuclear Information System (INIS)

    Loskiewicz, J.; Olko, P.; Swakon, J.; Bogacz, J.; Janik, M.; Mazur, D.; Mazur, J.

    1998-01-01

    The variation of radon concentration in some houses in the Krakow region was investigated in order to compare results obtained using various measuring techniques. It is concluded that short-term measurements should last at least 4 days to avoid errors exceeding 30%; that weather parameters and human activity during the measurement should be recorded; that measurements should be repeated several times under various weather conditions; that seasonal variation in the region should be taken into account. (A.K.)

  18. Geochemical modelling of groundwater evolution and residence time at the Kivetty site

    Energy Technology Data Exchange (ETDEWEB)

    Pitkaenen, P.; Luukkonen, A. [VTT Communities and Infrastructure, Espoo (Finland); Ruotsalainen, P. [Fintact Oy, Helsinki (Finland); Leino-Forsman, H.; Vuorinen, U. [VTT Chemical Technology, Espoo (Finland)

    1998-12-01

    groundwater are due to carbonate reactions: oxidising of organic carbon, and dissolution and precipitation of calcite. The carbonate reactions and slight hydrolysis of silicates stabilise the pH value at 8-9. In addition to aerobic oxidation of organic matter, oxidative dissolution of biotite seems to be an important oxygen consumer at shallow depth during recharge. The most important process controlling the redox state deeper in the bedrock was interpreted to be the microbially mediated sulphate reduction with simultaneous anaerobic respiration of organic carbon. This process buffers the redox level of about -200 - -300 mV depending on the pH. Even though the salinities of the groundwater samples and mass-transfer along flow paths remain low, the geochemical evolution was fully developed and has reached quite a stable thermodynamic state. The residence times of the groundwater samples cover the time span back to glaciation. Young ages seem to be limited to the upper part of bedrock, and any really dynamic natural flowpath with deep observed recently recharged water cannot be demonstrated. Deglacial or subglacial ages (over 9,700 years old at Kivetty) are typical below the 150-300m level in the bedrock. Subglacial waters are interpreted to derive from mixing of preglacial water and meltwater, the input of which is estimated to be about 20% at the most. Indications of elevated oxygen intrusion cannot be observed in groundwater having glacial signals. (orig.) 122 refs.

  19. Identifying residence times and streamflow generation processes using δ18O and δ2H in meso-scale catchments in the Abay/Upper Blue Nile, Ethiopia

    Science.gov (United States)

    Tekleab, S.; Wenninger, J.; Uhlenbrook, S.

    2013-08-01

    Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stable isotope composition in precipitation, spring water and streamflow were analyzed (i) to characterize the spatial and temporal variations of water fluxes; (ii) to estimate the mean residence time of water using a sine wave regression approach; and (iii) to identify runoff components using classical two component hydrograph separations at a seasonal time scale. The results show that the isotopic composition of precipitation exhibit marked seasonal variations, which suggests different sources of moisture generation for the rainfall in the study area. The Atlantic-Indian ocean, Congo basin, and the Sud swamps are the likely the potential moisture source areas during the main rainy (summer) season. While, the Indian-Arabian, and Mediterranean Sea moisture source areas during little rain (spring), and dry (winter) seasons. The spatial variation of the isotopic composition is affected by the amount effect and to less extent by altitude and temperature effects. A mean altitude effect of -0.12‰ (100 m)-1 for 18O and -0.58‰ (100 m)-1 for 2H were discernable in precipitation isotope composition. The seasonal variations of the isotopic signature of the spring water exhibit a damped response as compared to the river waters, which shows that the spring water has longer residence times than the river water. Results from the hydrograph separation at a seasonal time scale indicate the dominance of event water with an average of 71% and 64% of the total runoff during the wet season in the Chemoga and Jedeb catchment, respectively. The stable isotope compositions of streamflow samples were damped compared to the input function of precipitation for both catchments and this damping was

  20. Caregiver Person-Centeredness and Behavioral Symptoms in Nursing Home Residents With Dementia: A Timed-Event Sequential Analysis.

    Science.gov (United States)

    Gilmore-Bykovskyi, Andrea L; Roberts, Tonya J; Bowers, Barbara J; Brown, Roger L

    2015-06-01

    Evidence suggests that person-centered caregiving approaches may reduce dementia-related behavioral symptoms; however, little is known about the sequential and temporal associations between specific caregiver actions and behavioral symptoms. The aim of this study was to identify sequential associations between caregiver person-centered actions, task-centered actions, and resident behavioral symptoms and the temporal variation within these associations. Videorecorded observations of naturally occurring interactions (N = 33; 724min) between 12 nursing home (NH) residents with dementia and eight certified nursing assistants were coded for caregiver person-centered actions, task-centered actions, and resident behavioral symptoms and analyzed using timed-event sequential analysis. Although caregiver actions were predominantly person-centered, we found that resident behavioral symptoms were significantly more likely to occur following task-centered caregiver actions than person-centered actions. Findings suggest that the person-centeredness of caregivers is sequentially and temporally related to behavioral symptoms in individuals with dementia. Additional research examining the temporal structure of these relationships may offer valuable insights into the utility of caregiver person-centeredness as a low-cost strategy for improving behavioral symptom management in the NH setting. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. Quantitative measurement of the vibrational amplitude and phase in photorefractive time-average interferometry: A comparison with electronic speckle pattern interferometry

    DEFF Research Database (Denmark)

    Rohleder, Henrik; Petersen, Paul Michael; Marrakchi, A.

    1994-01-01

    and amplitude of the vibrating structure are demonstrated in photorefractive time average interferometry. The photorefractive interferometer is compared with the performance of a commercial electronic speckle pattern interferometer (ESPI). It is shown that the dynamic photorefractive holographic interferometer......Time-average interferometry is dealt with using four-wave mixing in photorefractive Bi12SiO20. By introducing a proper sinusoidal phase shift in the forward pump beam it is possible to measure the amplitude and phase everywhere on a vibrating object. Quantitative measurements of the phase...

  2. Increasing functional modularity with residence time in the co-distribution of native and introduced vascular plants.

    Science.gov (United States)

    Hui, Cang; Richardson, David M; Pyšek, Petr; Le Roux, Johannes J; Kučera, Tomáš; Jarošík, Vojtěch

    2013-01-01

    Species gain membership of regional assemblages by passing through multiple ecological and environmental filters. To capture the potential trajectory of structural changes in regional meta-communities driven by biological invasions, one can categorize species pools into assemblages of different residence times. Older assemblages, having passed through more environmental filters, should become more functionally ordered and structured. Here we calculate the level of compartmentalization (modularity) for three different-aged assemblages (neophytes, introduced after 1500 AD; archaeophytes, introduced before 1500 AD, and natives), including 2,054 species of vascular plants in 302 reserves in central Europe. Older assemblages are more compartmentalized than younger ones, with species composition, phylogenetic structure and habitat characteristics of the modules becoming increasingly distinctive. This sheds light on two mechanisms of how alien species are functionally incorporated into regional species pools: the settling-down hypothesis of diminishing stochasticity with residence time, and the niche-mosaic hypothesis of inlaid neutral modules in regional meta-communities.

  3. Isotopic and geochemical tracers in the evaluation of groundwater residence time and salinization problems at Santiago Island, Cape Verde

    Energy Technology Data Exchange (ETDEWEB)

    Carreira, Paula M.; Nunes, Dina [Quimica Analitica e Ambiental, IST/ITN, Universidade Tecnica de Lisboa, Estrada Nacional no. 10, 2686-953 Sacavem (Portugal); Marques, Jose M. [Centro de Petrologia e Geoquimica. Instituto Superior Tecnico, UTL, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Monteiro Santos, Fernando A. [Universidade de Lisboa-IDL, 1749-016 Lisboa (Portugal); Goncalves, Rui [Inst. Politecnico de Tomar, Quinta do Contador, Estrada da Serra, 2300 Tomar (Portugal); Pina, Antonio; Mota Gomes, Antonio [Instituto Superior de Educacao, Praia, Santiago (Cape Verde)

    2013-07-01

    Stable isotopes (δ{sup 18}O, δ{sup 2}H) and tritium ({sup 3}H), together with geochemistry and geophysical data, were used for evaluating groundwater recharge sources, flow paths, and residence times in a watershed on Santiago Island, Cape Verde, West Africa. Stable isotopes indicate the predominance of high-elevation precipitation that undergoes little evaporation prior to groundwater recharge. Low tritium concentrations at seven sampling sites indicate groundwater residence times greater than 50 years. Higher tritium values at other locations suggest more recent recharge. Young ages indicate local recharge and potential groundwater vulnerability to surface contamination and/or salt-water intrusion. Geochemical results indicate that water-rock interaction mechanisms are the major processes responsible for the groundwater quality (mainly calcium-bicarbonate type), reflecting the lithological composition of subsurface soil. (authors)

  4. Optimization of Drug Delivery Systems for Intraperitoneal Therapy to Extend the Residence Time of the Chemotherapeutic Agent

    Directory of Open Access Journals (Sweden)

    L. De Smet

    2013-01-01

    Full Text Available Intraperitoneal (IP chemotherapy is an effective way of treating peritoneal carcinomatosis of colorectal origin after complete cytoreduction. Although IP therapy has been already performed for many years, no standardized treatment design has been developed in terms of schedule, residence time, drug, or carrier solution. Because of the fast clearance of the conventional intravenous (IV drug delivery systems used for IP therapy, a lot of research is performed to optimize IP drug delivery and extend the residence time of the cytotoxic agent in the peritoneal cavity. This paper reviews the recent advances made in drug delivery systems for IP chemotherapy, discussing the use of microparticles, nanoparticles, liposomes, micelles, implants, and injectable depots for IP delivery.

  5. Measurement of residence time distribution of liquid phase in an industrial-scale continuous pulp digester using radiotracer technique.

    Science.gov (United States)

    Sheoran, Meenakshi; Goswami, Sunil; Pant, Harish J; Biswal, Jayashree; Sharma, Vijay K; Chandra, Avinash; Bhunia, Haripada; Bajpai, Pramod K; Rao, S Madhukar; Dash, A

    2016-05-01

    A series of radiotracer experiments was carried out to measure residence time distribution (RTD) of liquid phase (alkali) in an industrial-scale continuous pulp digester in a paper industry in India. Bromine-82 as ammonium bromide was used as a radiotracer. Experiments were carried out at different biomass and white liquor flow rates. The measured RTD data were treated and mean residence times in individual digester tubes as well in the whole digester were determined. The RTD was also analyzed to identify flow abnormalities and investigate flow dynamics of the liquid phase in the pulp digester. Flow channeling was observed in the first section (tube 1) of the digester. Both axial dispersion and tanks-in-series with backmixing models preceded with a plug flow component were used to simulate the measured RTD and quantify the degree of axial mixing. Based on the study, optimum conditions for operating the digester were proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Isotopic and geochemical tracers in the evaluation of groundwater residence time and salinization problems at Santiago Island, Cape Verde

    International Nuclear Information System (INIS)

    Carreira, Paula M.; Nunes, Dina; Marques, Jose M.; Monteiro Santos, Fernando A.; Goncalves, Rui; Pina, Antonio; Mota Gomes, Antonio

    2013-01-01

    Stable isotopes (δ 18 O, δ 2 H) and tritium ( 3 H), together with geochemistry and geophysical data, were used for evaluating groundwater recharge sources, flow paths, and residence times in a watershed on Santiago Island, Cape Verde, West Africa. Stable isotopes indicate the predominance of high-elevation precipitation that undergoes little evaporation prior to groundwater recharge. Low tritium concentrations at seven sampling sites indicate groundwater residence times greater than 50 years. Higher tritium values at other locations suggest more recent recharge. Young ages indicate local recharge and potential groundwater vulnerability to surface contamination and/or salt-water intrusion. Geochemical results indicate that water-rock interaction mechanisms are the major processes responsible for the groundwater quality (mainly calcium-bicarbonate type), reflecting the lithological composition of subsurface soil. (authors)

  7. The distribution of range sizes of native and alien plants in four European countries and the effects of residence time

    Czech Academy of Sciences Publication Activity Database

    Williamson, M.; Dehnen-Schmutz, K.; Kühn, I.; Hill, M.; Klotz, S.; Milbau, A.; Stout, J.; Pyšek, Petr

    2009-01-01

    Roč. 15, č. 1 (2009), s. 158-166 ISSN 1366-9516 R&D Projects: GA MŠk LC06073 Grant - others:Evropská komise(XE) SSPI-CT-2003-511202 Institutional research plan: CEZ:AV0Z60050516 Keywords : invasions * distribution range * residence time Subject RIV: EF - Botanics Impact factor: 4.224, year: 2009

  8. Successful invaders co-opt pollinators of native flora and accumulate insect pollinators with increasing residence time

    Czech Academy of Sciences Publication Activity Database

    Pyšek, Petr; Jarošík, Vojtěch; Chytrý, M.; Danihelka, Jiří; Kuhn, D.; Pergl, Jan; Tichý, L.; Biesmeijer, J. C.; Ellis, W. N.; Kunin, W. E.; Settele, J.

    2011-01-01

    Roč. 81, č. 2 (2011), s. 277-293 ISSN 0012-9615 R&D Projects: GA MŠk LC06073; GA ČR GA206/09/0563 Grant - others:European Comission(XE) GOCE-CT-2003-506675 Institutional research plan: CEZ:AV0Z60050516 Keywords : pollination * residence time * plant invasion Subject RIV: EF - Botanics Impact factor: 7.433, year: 2011

  9. Comparison of Residence Time Distributions of Liquid for Different Types of Input Signal Using a Stimulus-Response Technique

    Czech Academy of Sciences Publication Activity Database

    Čermáková, Jiřina; Siyakatshana, N.; Šilar, F.; Kudrna, V.; Jahoda, M.; Machoň, V.

    2003-01-01

    Roč. 57, č. 6 (2003), s. 427-431 ISSN 0366-6352. [International Conference of Slovak Society of Chemical Engineering /30./. Tatranské Matliare, 26.05.2003-30.05.2003] Institutional research plan: CEZ:AV0Z4072921 Keywords : stirred tank * stimulus-response technique * residence time distribution Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.226, year: 2003

  10. A multitracer approach to estimate groundwater residence time distributions at a managed aquifer recharge site

    Science.gov (United States)

    Popp, Andrea; Kipfer, Rolf

    2017-04-01

    Managed aquifer recharge (MAR) has become a common water management tool and serves various purposes such as improving the quality of groundwater (GW). At the study site, the Hardwald in Muttenz (Switzerland), MAR has been implemented in the mid-1950s to overcome increasing water demands. GW is artificially recharged with water from the river Rhine through a system of channels and ponds. The area is surrounded by potential contamination sites such as chemical industry, former landfills, a highway and a freight depot. Furthermore, the area shows a complex hydrogeologic setting with several fault zones and two main aquifers, the Quaternary Rhine gravel aquifer overlying a karstified Upper Muschelkalk limestone aquifer. Water from the deeper limestone aquifer is suspected to contain contaminants originating from the landfills. The fractures might serve as a hydraulic connection between the upper and lower aquifer. Further, groundwater pumping might enhance the mixing of recently infiltrated water with older water from the lower aquifer. Hence, the proximity to potential contamination sites and the complex geologic setting both pose risks for GW pollution and challenge the drinking water production in this area. To guarantee a safe drinking water supply, it is crucial to know the mixing patterns of young and old GW abstracted from the pumping wells. With this study we aim to determine the spatial variability of GW residence time distributions to differentiate between recently infiltrated river water and older groundwater. To reach our objectives, we use a combination of the following tracers to cover a wide range of possible GW ages: (1) radiogenic 222Rn (young water := <3 weeks); (2) tritium (3H) in combination with its tritiogenic decay product 3He (old water := 0.5-50 years); and (3) radiogenic 4He (very old water := 100-1000 years). Additionally, we analysed other dissolved (noble) gases (O2, N2, Ar, Kr) to estimate the amount of excess air and to derive the

  11. Geochemical modelling of groundwater evolution and residence time at the Olkiluoto site

    International Nuclear Information System (INIS)

    Pitkaenen, P.; Luukkonen, A.; Ruotsalainen, P.; Leino-Forsman, H.; Vuorinen, U.

    1999-05-01

    external conditions such as glaciation, palaeo Baltic stages, land uplift and ancient hydrothermal events, have had a significant effect on local palaeohydrogeological conditions. They have caused great variability, which is observable in the chemical data notably in salinity (up to 70 g/l), water type and contents of conservative parameters, such as Cl, Br and stable isotopes of water. However, their influence is also significant on the water-rock interaction that principally controls the pH and redox conditions - varying 7.5 to 8 and -200 to -300 mV, respectively - in the groundwater, although the calculated mass transfer in the reactions is minor compared with conservative mixing at the site. Calcite in fractures is interpreted to principally control pH level in groundwater. Sulphidic redox conditions dominate in the upper 500 m in brackish and slightly saline groundwater. Deeper sulphur species are absent and methanic processes are obtained. The water types can be connected to certain palaeo stages. This enables to estimate mean residence time of groundwaters. Current meteoric recharge stage (< 2500 a) mainly dominates in the upper 150 m. Groundwater from Litorina stage (7500-2500 a ago) forms the bulk at 100 - 250 m. Glacial melt water (about 10 000 a old) is an important component of groundwater between 100 - 500 m. However, any remarks of oxygen intrusion cannot be interpreted neither from mineralogy nor from groundwater. Deeper, subglacial and older saline groundwater predominates. Despite the current locations of different groundwater bodies it seems according to hydrogeochemical interpretation that dynamic flow conditions has been limited to upper 150 - 200 m. (orig.)

  12. Geochemical modelling of groundwater evolution and residence time at the Olkiluoto site

    Energy Technology Data Exchange (ETDEWEB)

    Pitkaenen, P.; Luukkonen, A. [VTT Communities and Infrastructure, Espoo (Finland); Ruotsalainen, P. [Fintact Oy (Finland); Leino-Forsman, H.; Vuorinen, U. [VTT Chemical Technology, Espoo (Finland)

    1999-05-01

    external conditions such as glaciation, palaeo Baltic stages, land uplift and ancient hydrothermal events, have had a significant effect on local palaeohydrogeological conditions. They have caused great variability, which is observable in the chemical data notably in salinity (up to 70 g/l), water type and contents of conservative parameters, such as Cl, Br and stable isotopes of water. However, their influence is also significant on the water-rock interaction that principally controls the pH and redox conditions - varying 7.5 to 8 and -200 to -300 mV, respectively - in the groundwater, although the calculated mass transfer in the reactions is minor compared with conservative mixing at the site. Calcite in fractures is interpreted to principally control pH level in groundwater. Sulphidic redox conditions dominate in the upper 500 m in brackish and slightly saline groundwater. Deeper sulphur species are absent and methanic processes are obtained. The water types can be connected to certain palaeo stages. This enables to estimate mean residence time of groundwaters. Current meteoric recharge stage (< 2500 a) mainly dominates in the upper 150 m. Groundwater from Litorina stage (7500-2500 a ago) forms the bulk at 100 - 250 m. Glacial melt water (about 10 000 a old) is an important component of groundwater between 100 - 500 m. However, any remarks of oxygen intrusion cannot be interpreted neither from mineralogy nor from groundwater. Deeper, subglacial and older saline groundwater predominates. Despite the current locations of different groundwater bodies it seems according to hydrogeochemical interpretation that dynamic flow conditions has been limited to upper 150 - 200 m. (orig.) 82 refs.

  13. DNA binding by PHF1 prolongs PRC2 residence time on chromatin and thereby promotes H3K27 methylation.

    Science.gov (United States)

    Choi, Jeongyoon; Bachmann, Andreas Linus; Tauscher, Katharina; Benda, Christian; Fierz, Beat; Müller, Jürg

    2017-12-01

    Polycomb repressive complex 2 (PRC2) trimethylates histone H3 at lysine 27 to mark genes for repression. We measured the dynamics of PRC2 binding on recombinant chromatin and free DNA at the single-molecule level using total internal reflection fluorescence (TIRF) microscopy. PRC2 preferentially binds free DNA with multisecond residence time and midnanomolar affinity. PHF1, a PRC2 accessory protein of the Polycomblike family, extends PRC2 residence time on DNA and chromatin. Crystallographic and functional studies reveal that Polycomblike proteins contain a winged-helix domain that binds DNA in a sequence-nonspecific fashion. DNA binding by this winged-helix domain accounts for the prolonged residence time of PHF1-PRC2 on chromatin and makes it a more efficient H3K27 methyltranferase than PRC2 alone. Together, these studies establish that interactions with DNA provide the predominant binding affinity of PRC2 for chromatin. Moreover, they reveal the molecular basis for how Polycomblike proteins stabilize PRC2 on chromatin and stimulate its activity.

  14. Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists

    Science.gov (United States)

    Seow, Vernon; Lim, Junxian; Cotterell, Adam J.; Yau, Mei-Kwan; Xu, Weijun; Lohman, Rink-Jan; Kok, W. Mei; Stoermer, Martin J.; Sweet, Matthew J.; Reid, Robert C.; Suen, Jacky Y.; Fairlie, David P.

    2016-04-01

    Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1-3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents.

  15. Survey of some natural decay-series isotopes in the Wairakei geothermal area and possible residence-time applications

    International Nuclear Information System (INIS)

    Concentrations of selected isotopes in the uranium decay series were determined for samples collected from the Wairakei, Broadlands/Ohaaki and Waiotapu areas. /sup 226/Ra concentrations were found to be low (0.05-0.22 dpm/l), similar to values reported in neutral hot springs at Tatun geothermal area, Taiwan, but lower than other geothermal systems (Yellowstone, USA, and Latera, Central Italy) (up to 25 dpm/l). The potential of /sup 226/Ra//sup 228/Ra ratios for indicating water residence times could not be explored because /sup 228/Ra data was not available. /sup 222/Rn concentrations are higher and related to steam fractions and CO/sub 2/ concentrations. The short half-life (3.8 days) makes /sup 222/Rn suitable for estimating residence times of radon in steam, and therefore the distance of travel of steam from its source (e.g., wells WK9 and 52). /sup 210/Pb and /sup 210/Po concentrations were very low and less than detection limits in many of the Wairakei waters; no residence time applications are apparent for these isotopes. (author). 11 refs.; 5 figs.; 3 tabs

  16. Receptor residence time trumps drug-likeness and oral bioavailability in determining efficacy of complement C5a antagonists

    Science.gov (United States)

    Seow, Vernon; Lim, Junxian; Cotterell, Adam J.; Yau, Mei-Kwan; Xu, Weijun; Lohman, Rink-Jan; Kok, W. Mei; Stoermer, Martin J.; Sweet, Matthew J.; Reid, Robert C.; Suen, Jacky Y.; Fairlie, David P.

    2016-01-01

    Drug discovery and translation are normally based on optimizing efficacy by increasing receptor affinity, functional potency, drug-likeness (rule-of-five compliance) and oral bioavailability. Here we demonstrate that residence time of a compound on its receptor has an overriding influence on efficacy, exemplified for antagonists of inflammatory protein complement C5a that activates immune cells and promotes disease. Three equipotent antagonists (3D53, W54011, JJ47) of inflammatory responses to C5a (3nM) were compared for drug-likeness, receptor affinity and antagonist potency in human macrophages, and anti-inflammatory efficacy in rats. Only the least drug-like antagonist (3D53) maintained potency in cells against higher C5a concentrations and had a much longer duration of action (t1/2 ~ 20 h) than W54011 or JJ47 (t1/2 ~ 1–3 h) in inhibiting macrophage responses. The unusually long residence time of 3D53 on its receptor was mechanistically probed by molecular dynamics simulations, which revealed long-lasting interactions that trap the antagonist within the receptor. Despite negligible oral bioavailability, 3D53 was much more orally efficacious than W54011 or JJ47 in preventing repeated agonist insults to induce rat paw oedema over 24 h. Thus, residence time on a receptor can trump drug-likeness in determining efficacy, even oral efficacy, of pharmacological agents. PMID:27094554

  17. MERRA 2D IAU Diagnostic, Land Only States and Diagnostics, Time Average 1-hourly (2/3x1/2L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXLND or tavg1_2d_lnd_Nx data product is the MERRA Data Assimilation System 2-Dimensional land surface diagnostic that is time averaged single-level at the...

  18. MERRA Chem 3D IAU, Precip Mass Flux, Time average 3-hourly (eta coord edges, 1.25X1L73) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3FECHM or tavg3_3d_chm_Fe data product is the MERRA Data Assimilation System Chemistry 3-Dimensional chemistry on layers edges that is time averaged, 3D model...

  19. MERRA Chem 3D IAU States Cloud Precip, Time average 3-hourly (eta coord, 1.25x1L72) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3FVCHM or tavg3_3d_chm_Fv data product is the MERRA Data Assimilation System Chemistry 3-Dimensional chemistry on layers file that is time averaged, 3D model...

  20. MERRA 2D IAU Diagnostic, Radiation Surface and TOA, Time Average 1-hourly (2/3x1/2L1) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXRAD or tavg1_2d_rad_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface and TOA radiation flux that is time averaged single-level...

  1. Manipulation of a Bose-Einstein condensate by a time-averaged orbiting potential using phase jumps of the rotating field

    NARCIS (Netherlands)

    Cleary, P.W.; Hijmans, T.W.; Walraven, J.T.M.

    2010-01-01

    We report on the manipulation of the center-of-mass motion ("sloshing") of a Bose-Einstein condensate in a time-averaged orbiting potential (TOP) trap. We start with a condensate at rest in the center of a static trapping potential. When suddenly replacing the static trap with a TOP trap centered

  2. How Well Does High School Grade Point Average Predict College Performance by Student Urbanicity and Timing of College Entry? REL 2017-250

    Science.gov (United States)

    Hodara, Michelle; Lewis, Karyn

    2017-01-01

    This report is a companion to a study that found that high school grade point average was a stronger predictor of performance in college-level English and math than were standardized exam scores among first-time students at the University of Alaska who enrolled directly in college-level courses. This report examines how well high school grade…

  3. Maintaining social cohesion is a more important determinant of patch residence time than maximizing food intake rate in a group-living primate, Japanese macaque (Macaca fuscata).

    Science.gov (United States)

    Kazahari, Nobuko

    2014-04-01

    Animals have been assumed to employ an optimal foraging strategy (e.g., rate-maximizing strategy). In patchy food environments, intake rate within patches is positively correlated with patch quality, and declines as patches are depleted through consumption. This causes patch-leaving and determines patch residence time. In group-foraging situations, patch residence times are also affected by patch sharing. Optimal patch models for groups predict that patch residence times decrease as the number of co-feeding animals increases because of accelerated patch depletion. However, group members often depart patches without patch depletion, and their patch residence time deviates from patch models. It has been pointed out that patch residence time is also influenced by maintaining social proximity with others among group-living animals. In this study, the effects of maintaining social cohesion and that of rate-maximizing strategy on patch residence time were examined in Japanese macaques (Macaca fuscata). I hypothesized that foragers give up patches to remain in the proximity of their troop members. On the other hand, foragers may stay for a relatively long period when they do not have to abandon patches to follow the troop. In this study, intake rate and foraging effort (i.e., movement) did not change during patch residency. Macaques maintained their intake rate with only a little foraging effort. Therefore, the patches were assumed to be undepleted during patch residency. Further, patch residence time was affected by patch-leaving to maintain social proximity, but not by the intake rate. Macaques tended to stay in patches for short periods when they needed to give up patches for social proximity, and remained for long periods when they did not need to leave to keep social proximity. Patch-leaving and patch residence time that prioritize the maintenance of social cohesion may be a behavioral pattern in group-living primates.

  4. Modeling sediment transport processes and residence times in the shallow coastal bay complex of the Virginia Coast Reserve

    Science.gov (United States)

    Safak, I.; Wiberg, P. L.

    2011-12-01

    Patterns of sediment transport and particle residence times influence the morphology and ecology of shallow coastal bays in important ways. The Virginia Coast Reserve (VCR), a barrier island-lagoon-marsh system on the Eastern Shore of Virginia, is typical of many shallow coastal bay complexes that lack a significant fluvial source of freshwater and sediment. Sediment redistribution within the bays in response to storms and sea-level rise, together with the dynamics of marsh and lagoon-bottom plants, largely governs the morphological evolution of this system. There are also important feedbacks between sediment and ecosystem dynamics. This is particularly true in the VCR, which is relatively unaffected by human activities. As a step towards evaluating the impact of hydrodynamics on sediment and ecological processes in the VCR, a single unified model that accounts for circulation, surface waves, wave-current interaction, and sediment processes is employed. This three-dimensional unstructured grid finite-volume coastal ocean model (FVCOM) is validated with field observations of wind- and tide-induced water flow (water level and current velocities) in Hog Island Bay, centrally located within the VCR. Here, the resulting patterns of sediment transport and particle residence times over event and seasonal time scales are presented. Water and particle exchange within the VCR and between the VCR and the ocean is examined with the Lagrangian particle-tracking module in FVCOM. We focus on three bays with strongly varying bathymetry and coastline geometry, which are also located along a gradient of nitrogen input to the system. The results indicate that residence time of particles within the system vary greatly depending on the location of particle release, bay morphology, and wind conditions. The implications for morphologic evolution and ecosystem response to climate and land-use changes are evaluated.

  5. Identification and Sensitivity Analysis for Average Causal Mediation Effects with Time-Varying Treatments and Mediators: Investigating the Underlying Mechanisms of Kindergarten Retention Policy.

    Science.gov (United States)

    Park, Soojin; Steiner, Peter M; Kaplan, David

    2018-03-01

    Considering that causal mechanisms unfold over time, it is important to investigate the mechanisms over time, taking into account the time-varying features of treatments and mediators. However, identification of the average causal mediation effect in the presence of time-varying treatments and mediators is often complicated by time-varying confounding. This article aims to provide a novel approach to uncovering causal mechanisms in time-varying treatments and mediators in the presence of time-varying confounding. We provide different strategies for identification and sensitivity analysis under homogeneous and heterogeneous effects. Homogeneous effects are those in which each individual experiences the same effect, and heterogeneous effects are those in which the effects vary over individuals. Most importantly, we provide an alternative definition of average causal mediation effects that evaluates a partial mediation effect; the effect that is mediated by paths other than through an intermediate confounding variable. We argue that this alternative definition allows us to better assess at least a part of the mediated effect and provides meaningful and unique interpretations. A case study using ECLS-K data that evaluates kindergarten retention policy is offered to illustrate our proposed approach.

  6. Catchment virtual observatory for sharing flow and transport models outputs: using residence time distribution to compare contrasting catchments

    Science.gov (United States)

    Thomas, Zahra; Rousseau-Gueutin, Pauline; Kolbe, Tamara; Abbott, Ben; Marcais, Jean; Peiffer, Stefan; Frei, Sven; Bishop, Kevin; Le Henaff, Geneviève; Squividant, Hervé; Pichelin, Pascal; Pinay, Gilles; de Dreuzy, Jean-Raynald

    2017-04-01

    The distribution of groundwater residence time in a catchment provides synoptic information about catchment functioning (e.g. nutrient retention and removal, hydrograph flashiness). In contrast with interpreted model results, which are often not directly comparable between studies, residence time distribution is a general output that could be used to compare catchment behaviors and test hypotheses about landscape controls on catchment functioning. In this goal, we created a virtual observatory platform called Catchment Virtual Observatory for Sharing Flow and Transport Model Outputs (COnSOrT). The main goal of COnSOrT is to collect outputs from calibrated groundwater models from a wide range of environments. By comparing a wide variety of catchments from different climatic, topographic and hydrogeological contexts, we expect to enhance understanding of catchment connectivity, resilience to anthropogenic disturbance, and overall functioning. The web-based observatory will also provide software tools to analyze model outputs. The observatory will enable modelers to test their models in a wide range of catchment environments to evaluate the generality of their findings and robustness of their post-processing methods. Researchers with calibrated numerical models can benefit from observatory by using the post-processing methods to implement a new approach to analyzing their data. Field scientists interested in contributing data could invite modelers associated with the observatory to test their models against observed catchment behavior. COnSOrT will allow meta-analyses with community contributions to generate new understanding and identify promising pathways forward to moving beyond single catchment ecohydrology. Keywords: Residence time distribution, Models outputs, Catchment hydrology, Inter-catchment comparison

  7. The Effects of Particle Size, Different Corn Stover Components, and Gas Residence Time on Torrefaction of Corn Stover

    Directory of Open Access Journals (Sweden)

    Sarah Rahn

    2012-04-01

    Full Text Available Large scale biofuel production will be possible only if significant quantities of biomass feedstock can be stored, transported, and processed in an economic and sustainable manner. Torrefaction has the potential to significantly reduce the cost of transportation, storage, and downstream processing through the improvement of physical and chemical characteristics of biomass. The main objective of this study was to investigate the effects of particle size, plant components, and gas residence time on the production of torrefied corn (Zea mays stover. Different particle sizes included 0.85 mm and 20 mm. Different stover components included ground corn stover, whole corn stalk, stalk shell and pith, and corn cob shell. Three different purge gas residence times were employed to assess the effects of interaction of volatiles and torrefied biomass. Elemental analyses were performed on all of the samples, and the data obtained was used to estimate the energy contents and energy yields of different torrefied biomass samples. Particle density, elemental composition, and fiber composition of raw biomass fractions were also determined. Stalk pith torrefied at 280 °C and stalk shell torrefied at 250 °C had highest and lowest dry matter loss, of about 44% and 13%, respectively. Stalk pith torrefied at 250 °C had lowest energy density of about 18–18.5 MJ/kg, while cob shell torrefied at 280 °C had the highest energy density of about 21.5 MJ/kg. The lowest energy yield, at 59%, was recorded for stalk pith torrefied at 280 °C, whereas cob and stalk shell torrefied at 250 °C had highest energy yield at 85%. These differences were a consequence of the differences in particle densities, hemicellulose quantities, and chemical properties of the original biomass samples. Gas residence time did not have a significant effect on the aforementioned parameters.

  8. Target Residence Time-Guided Optimization on TTK Kinase Results in Inhibitors with Potent Anti-Proliferative Activity.

    Science.gov (United States)

    Uitdehaag, Joost C M; de Man, Jos; Willemsen-Seegers, Nicole; Prinsen, Martine B W; Libouban, Marion A A; Sterrenburg, Jan Gerard; de Wit, Joeri J P; de Vetter, Judith R F; de Roos, Jeroen A D M; Buijsman, Rogier C; Zaman, Guido J R

    2017-07-07

    The protein kinase threonine tyrosine kinase (TTK; also known as Mps1) is a critical component of the spindle assembly checkpoint and a promising drug target for the treatment of aggressive cancers, such as triple negative breast cancer. While the first TTK inhibitors have entered clinical trials, little is known about how the inhibition of TTK with small-molecule compounds affects cellular activity. We studied the selective TTK inhibitor NTRC 0066-0, which was developed in our own laboratory, together with 11 TTK inhibitors developed by other companies, including Mps-BAY2b, BAY 1161909, BAY 1217389 (Bayer), TC-Mps1-12 (Shionogi), and MPI-0479605 (Myrexis). Parallel testing shows that the cellular activity of these TTK inhibitors correlates with their binding affinity to TTK and, more strongly, with target residence time. TTK inhibitors are therefore an example where target residence time determines activity in in vitro cellular assays. X-ray structures and thermal stability experiments reveal that the most potent compounds induce a shift of the glycine-rich loop as a result of binding to the catalytic lysine at position 553. This "lysine trap" disrupts the catalytic machinery. Based on these insights, we developed TTK inhibitors, based on a (5,6-dihydro)pyrimido[4,5-e]indolizine scaffold, with longer target residence times, which further exploit an allosteric pocket surrounding Lys553. Their binding mode is new for kinase inhibitors and can be classified as hybrid Type I/Type III. These inhibitors have very potent anti-proliferative activity that rivals classic cytotoxic therapy. Our findings will open up new avenues for more applications for TTK inhibitors in cancer treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Impact of Temperature and Hydrological Residence Time on the Fate and Transport of Iron and Organic Carbon in Subalpine Wetlands

    Science.gov (United States)

    Schneider, L. M.; Borch, T.; Rhoades, C.; Pallud, C. E.

    2015-12-01

    Wetlands contain one third of the planet's soil carbon (C) and are characterized by markedly different chemical and physical environments than terrestrial ecosystems. The hydrologic residence time and temperature in wetlands influences their redox conditions and thus biogeochemical reaction rates. In these environments, transformation and movement of C and iron (Fe) are closely linked due to the sorption of organic C by solid Fe(III)-phases. Therefore, changes in Fe biogeochemical cycling will influence the size and turnover rate of soil C pools, which could negatively impact water quality and C storage. We examined the effects of hydrologic residence time and temperature on reduction of autochtonous Fe(III)-oxides. Fe(II)-export rates, used as a lower bound for bulk Fe(III)-reduction rates, and dissolved organic carbon (DOC) export rates were measured on intact mineral soil cores using flow-through reactor experiments exposed to temperatures based on mean annual conditions (6°, 12°, and 18°C). Soils were from a slope and a depressional subalpine wetland (USDA Fraser Experimental Forest, CO, USA), characterized by different hydrologic residence times, were compared. In the depressional wetland we observed the shallower soil depths have higher overall Fe(II)-export rates than the deeper soil depths. As temperature increases, Fe(II)-export rate increases, with a more than doubling in magnitude from 12 to 18° C. In comparing sites that are continuously inundated to those that are seasonally inundated, surprisingly we see higher Fe(II)-export rates in the seasonally inundated sites for all temperatures and depths. In the slope wetland we observed an opposite trend with depth and with temperature, with Fe(II)-export rates declining by almost an order of magnitude between 6 and 12°C. In addition, our results showed a positive correlation between Fe(II)-export rates and DOC export rates suggesting Fe(III)-reduction exerts a biogeochemical control on water quality

  10. Fly Ash Formation during Suspension-Firing of Biomass. Effects of Residence Time and Fuel-Type

    DEFF Research Database (Denmark)

    Damø, Anne Juul; Jensen, Peter Arendt; Jappe Frandsen, Flemming

    2017-01-01

    particles were subjected to various analyses, including char burnout level, particle size distribution, elemental composition, and particle morphology and composition. Furthermore, the transient release, i.e. the vaporization of the flame-volatile inorganic elements K, Cl and S, from the burning fuel...... particles to the gas phase, has been quantified by using two different calculation methods. The ash formation mechanisms were found to be quite similar for straw and wood. The degree of conversion (char burn-out level) was generally good at residence times ≥ 1s. The size distribution of the residual fly ash...

  11. Determination of the residence time of rain water in some hydrographic basins by means of stable isotopes

    International Nuclear Information System (INIS)

    Goncalves, A.R.L.

    1979-10-01

    Samples of rain-and river water, monthly collected during one year from ten stations of the Amazon basin analysed in their 18 O and D content. The residence time of rain water for each station was determined using the values of Δ 18 O(%o) and ΔD(%). The values of Δ 18 O(%o) were correlated with the precipitation ones (mm) in order to determine the occurence of 'amount effect' in the stations. An analysis of samples was done along the Amazon River for simple observation of the 'isotopic fractionation' phenomenon the values of Δ 18 O(%o). (Author) [pt

  12. Vibrational Spectra of β″-Type BEDT-TTF Salts: Relationship between Conducting Property, Time-Averaged Site Charge and Inter-Molecular Distance

    Directory of Open Access Journals (Sweden)

    Takashi Yamamoto

    2012-07-01

    Full Text Available The relationship between the conducting behavior and the degree of charge fluctuation in the β″-type BEDT-TTF salts is reviewed from the standpoints of vibrational spectroscopy and crystal structure. A group of β″-type ET salts demonstrates the best model compounds for achieving the above relationship because the two-dimensional structure is simple and great diversity in conducting behavior is realized under ambient pressure. After describing the requirement for the model compound, the methodology for analyzing the results of the vibrational spectra is presented. Vibrational spectroscopy provides the time-averaged molecular charge, the charge distribution in the two-dimensional layer, and the inter-molecular interactions, etc. The experimental results applied to 2/3-filled and 3/4-filled β″-type ET salts are reported. These experimental results suggest that the conducting property, the difference in the time-averaged molecular charges between the ionic and neutral-like sites, the alternation in the inter-molecular distances and the energy levels in the charge distributions are relevant to one another. The difference in the time-averaged molecular charges, ∆ρ, is a useful criterion for indicating conducting behavior. All superconductors presented in this review are characterized as small but finite ∆ρ.

  13. Effects of average uncertainty and trial-type frequency on choice response time: A hierarchical extension of Hick/Hyman Law.

    Science.gov (United States)

    Mordkoff, J Toby

    2017-12-01

    Hick/Hyman Law is the linear relationship between average uncertainty and mean response time across entire blocks of trials. While unequal trial-type frequencies within blocks can be used to manipulate average uncertainty, the current version of the law does not apply to or account for the differences in mean response time across the different trial types contained in a block. Other simple predictors of the effects of trial-type frequency also fail to produce satisfactory fits. In an attempt to resolve this limitation, the present work takes a hierarchical approach, first fitting the block-level data using average uncertainty (i.e., Hick/Hyman Law is given priority), then fitting the remaining trial-level differences using various versions of trial-type frequency. The model that employed the relative probability of occurrence as the second-layer predictor produced very strong fits, thereby extending Hick/Hyman Law to the level of trial types within blocks. The advantages and implications of this hierarchical model are briefly discussed.

  14. Sewage sludge ash to phosphate fertilizer by chlorination and thermal treatment: residence time requirements for heavy metal removal.

    Science.gov (United States)

    Nowak, Benedikt; Wegerer, Harald; Aschenbrenner, Philipp; Rechberger, Helmut; Winter, Franz

    2012-01-01

    Heavy metal removal from sewage sludge ash can be performed by mixing the ash with environmentally compatible chlorides (e.g. CaCl2 or MgCl2) and water, pelletizing the mixture and treating the pellets in a rotary reactor at about 1000 degrees C. Thermogravimetry-mass spectroscopy, muffle oven tests (500-1150 degrees C) and investigations in a laboratory-scale rotary reactor (950-1050 degrees C, residence time 1-25 min) were carried out. In the rotary reactor, up to 97% of Cu, 95% Pb and 95% Zn can be removed at 1050 degrees C. As Cl release starts from 400 degrees C (obtained from thermogravimetry-mass spectrometry experiments), heavy metals are already removed partially within the heating period. This heavy metal removal can be described as being similar to a first-order rate law. To meet the limit values specified in the Austrian and German fertilizer ordinances, residence times of the order of minutes are sufficient at 950 degrees C.

  15. Radiotracer investigation on the measurement of residence time distribution in an ethyl acetate reactor system with a large recycle ratio.

    Science.gov (United States)

    Datta, Arghya; Kumar Gupta, Raj; Goswami, Sunil; Kumar Sharma, Vijay; Bhunia, Haripada; Singh, Damandeep; Jagat Pant, Harish

    2017-12-01

    A radiotracer investigation was carried out on the measurement of residence time distribution (RTD) of process fluid in an industrial-scale ethyl acetate reactor system, which consists of two independent reactors with recirculation and connected in series with each other. Bromine-82 as ammonium bromide was used as the radiotracer for the RTD experiments at different operating conditions. The individual reactors and the overall reactor system were modelled using physically representative phenomenological models comprising of continuously stirred tank reactors (CSTRs). The results showed that the recirculation rate considerably affected the flow mixing behaviour and mean residence time of the process fluid in the reactor system. The results also showed that there was bypassing of the fluid in the first reactor that ranged from 12% to 22% and 40% dead volume at different operating conditions, whereas the second reactor behaved closely as an ideal CSTR. The results of the investigation can be used to optimise the process parameters and design new improved reactor systems for the production of ethyl acetate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Most suitable mother wavelet for the analysis of fractal properties of stride interval time series via the average wavelet coefficient method.

    Science.gov (United States)

    Zhang, Zhenwei; VanSwearingen, Jessie; Brach, Jennifer S; Perera, Subashan; Sejdić, Ervin

    2017-01-01

    Human gait is a complex interaction of many nonlinear systems and stride intervals exhibiting self-similarity over long time scales that can be modeled as a fractal process. The scaling exponent represents the fractal degree and can be interpreted as a "biomarker" of relative diseases. The previous study showed that the average wavelet method provides the most accurate results to estimate this scaling exponent when applied to stride interval time series. The purpose of this paper is to determine the most suitable mother wavelet for the average wavelet method. This paper presents a comparative numerical analysis of 16 mother wavelets using simulated and real fractal signals. Simulated fractal signals were generated under varying signal lengths and scaling exponents that indicate a range of physiologically conceivable fractal signals. The five candidates were chosen due to their good performance on the mean square error test for both short and long signals. Next, we comparatively analyzed these five mother wavelets for physiologically relevant stride time series lengths. Our analysis showed that the symlet 2 mother wavelet provides a low mean square error and low variance for long time intervals and relatively low errors for short signal lengths. It can be considered as the most suitable mother function without the burden of considering the signal length. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Combining site occupancy, breeding population sizes and reproductive success to calculate time-averaged reproductive output of different habitat types: an application to Tricolored Blackbirds.

    Directory of Open Access Journals (Sweden)

    Marcel Holyoak

    Full Text Available In metapopulations in which habitat patches vary in quality and occupancy it can be complicated to calculate the net time-averaged contribution to reproduction of particular populations. Surprisingly, few indices have been proposed for this purpose. We combined occupancy, abundance, frequency of occurrence, and reproductive success to determine the net value of different sites through time and applied this method to a bird of conservation concern. The Tricolored Blackbird (Agelaius tricolor has experienced large population declines, is the most colonial songbird in North America, is largely confined to California, and breeds itinerantly in multiple habitat types. It has had chronically low reproductive success in recent years. Although young produced per nest have previously been compared across habitats, no study has simultaneously considered site occupancy and reproductive success. Combining occupancy, abundance, frequency of occurrence, reproductive success and nest failure rate we found that that large colonies in grain fields fail frequently because of nest destruction due to harvest prior to fledging. Consequently, net time-averaged reproductive output is low compared to colonies in non-native Himalayan blackberry or thistles, and native stinging nettles. Cattail marshes have intermediate reproductive output, but their reproductive output might be improved by active management. Harvest of grain-field colonies necessitates either promoting delay of harvest or creating alternative, more secure nesting habitats. Stinging nettle and marsh colonies offer the main potential sources for restoration or native habitat creation. From 2005-2011 breeding site occupancy declined 3x faster than new breeding colonies were formed, indicating a rapid decline in occupancy. Total abundance showed a similar decline. Causes of variation in the value for reproduction of nesting substrates and factors behind continuing population declines merit urgent

  18. How Entrustment Is Informed by Holistic Judgments Across Time in a Family Medicine Residency Program: An Ethnographic Nonparticipant Observational Study

    NARCIS (Netherlands)

    Sagasser, M.H.; Fluit, C.R.M.G.; Weel, C. van; Vleuten, C.P.M. van der; Kramer, A.W.M.

    2017-01-01

    PURPOSE: Entrustment has mainly been conceptualized as delegating discrete professional tasks. Because residents provide most of their patient care independently, not all resident performance is visible to supervisors; the entrustment process involves more than granting discrete tasks. This study

  19. Foraging strategy of a Neotropical primate: how intrinsic and extrinsic factors influence destination and residence time

    DEFF Research Database (Denmark)

    Plante, Sabrina; Colchero, Fernando; Calmé, Sophie

    2014-01-01

    accounting for intrinsic and extrinsic factors, which are often overlooked when modelling foraging behaviour. 2.We identified the decision rules for foraging in black howler monkeys (Alouatta pigra), according to food preferences, locations of high quality patches and previously eaten trees, phenology...... of food resources and hunger state. We depicted foraging in two stages: 1) the choice of the immediate next tree and 2) the time spent on this tree. We used a recently developed model for inference of movement processes, incorporating resource selection functions into a Markov Chain framework. 3.We found....... Time spent on a tree was positively and strongly affected by the presence of preferred food items, but not by its species. We also showed that time spent on trees increased as a function of satiation state. We suggest that the strategy adopted by black howlers tends to be efficient because choosing...

  20. A decade of robot-assisted radical prostatectomy training: Time-based metrics and qualitative grading for fellows and residents.

    Science.gov (United States)

    Altok, Muammer; Achim, Mary F; Matin, Surena F; Pettaway, Curtis A; Chapin, Brian F; Davis, John W

    2018-01-01

    As modern urology residency and fellowship training in robot-assisted surgery evolves toward standardized curricula (didactics, dry/wet-laboratory exercises, and surgical assistance), additional tools are needed to evaluate on-console performance. At the start of our robotics program in 2006, we set-up a time- and quality-based evaluation program and aim to consolidate this data into a simple set of metrics for self-evaluation. Using our index procedure of robot-assisted radical prostatectomy (RARP), we prospectively collected data on 2,215 cases over 10 years from 6 faculty surgeons and 94 trainees (43 urologic oncology fellows and 51 urology residents). The steps of the operation were divided into 11 consistent steps, and the metrics included time to completion and quality using a 6-level grading system. Time metrics were consolidated into quartiles for benchmarking. The median times for trainees to complete each step were 15% to 120% higher than those of the staff (Pstaff results. Steps performed by trainees were carefully chosen for a high success rate, and on our Likert-like scale were graded 4 to 5 in more than 95% of cases. There were no grade 0 (very poor) cases, and grades 1 (multiple technical errors) and 2 (could not be completed but without safety issues) were rare (staff. As a trainee progress through a rotation, these benchmarks can assist in prioritizing the need for more attention to a basic step vs. progression to more advanced steps. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Elucidating fluctuating diffusivity in center-of-mass motion of polymer models with time-averaged mean-square-displacement tensor

    Science.gov (United States)

    Miyaguchi, Tomoshige

    2017-10-01

    There have been increasing reports that the diffusion coefficient of macromolecules depends on time and fluctuates randomly. Here a method is developed to elucidate this fluctuating diffusivity from trajectory data. Time-averaged mean-square displacement (MSD), a common tool in single-particle-tracking (SPT) experiments, is generalized to a second-order tensor with which both magnitude and orientation fluctuations of the diffusivity can be clearly detected. This method is used to analyze the center-of-mass motion of four fundamental polymer models: the Rouse model, the Zimm model, a reptation model, and a rigid rodlike polymer. It is found that these models exhibit distinctly different types of magnitude and orientation fluctuations of diffusivity. This is an advantage of the present method over previous ones, such as the ergodicity-breaking parameter and a non-Gaussian parameter, because with either of these parameters it is difficult to distinguish the dynamics of the four polymer models. Also, the present method of a time-averaged MSD tensor could be used to analyze trajectory data obtained in SPT experiments.

  2. Mean residence time of kaolinite and smectite-bound organic matter in mozambiquan soils

    NARCIS (Netherlands)

    Wattel-Koekkoek, E.J.W.; Buurman, P.

    2004-01-01

    To gain understanding about the process of global warming, it is essential to study the global C cycle. In the global C cycle, soil organic matter (SOM) is a major source and sink of atmospheric C. Turnover times of C in these soil organic compounds vary from hours to thousands of years. Clay

  3. Estimation of U.S. sewer residence time distributions for national-scale risk assessment of down-the-drain chemicals.

    Science.gov (United States)

    Kapo, Katherine E; Paschka, Michael; Vamshi, Raghu; Sebasky, Megan; McDonough, Kathleen

    2017-12-15

    Sewer residence time (the amount of time a given volume of wastewater resides in a sewer system prior to treatment) can have a significant influence on predictions of environmental fate and transport of wastewater constituents and corresponding risk assessment. In this study, a geographic information systems-based approach for estimating the distribution of sewer residence times for the U.S. was developed using road networks as a spatial proxy for sewer networks. The suitability of the approach was evaluated using case study municipalities, and the approach was subsequently extrapolated to 3422 wastewater treatment facilities of varying size across the U.S. to estimate a national distribution of sewer residence times. The estimated national median residence time for the U.S. was 3.3h. Facilities serving smaller municipalities (residence times to facilities serving larger municipalities, though the latter comprise a greater proportion of overall national wastewater volume. The results of this study provide an important data resource in combination with chemical in-sewer biodegradation data to enable probabilistic risk assessment of consumer product chemicals disposed of down the drain. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Field evaluation of the error arising from inadequate time averaging in the standard use of depth-integrating suspended-sediment samplers

    Science.gov (United States)

    Topping, David J.; Rubin, David M.; Wright, Scott A.; Melis, Theodore S.

    2011-01-01

    Several common methods for measuring suspended-sediment concentration in rivers in the United States use depth-integrating samplers to collect a velocity-weighted suspended-sediment sample in a subsample of a river cross section. Because depth-integrating samplers are always moving through the water column as they collect a sample, and can collect only a limited volume of water and suspended sediment, they collect only minimally time-averaged data. Four sources of error exist in the field use of these samplers: (1) bed contamination, (2) pressure-driven inrush, (3) inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration, and (4) inadequate time averaging. The first two of these errors arise from misuse of suspended-sediment samplers, and the third has been the subject of previous study using data collected in the sand-bedded Middle Loup River in Nebraska. Of these four sources of error, the least understood source of error arises from the fact that depth-integrating samplers collect only minimally time-averaged data. To evaluate this fourth source of error, we collected suspended-sediment data between 1995 and 2007 at four sites on the Colorado River in Utah and Arizona, using a P-61 suspended-sediment sampler deployed in both point- and one-way depth-integrating modes, and D-96-A1 and D-77 bag-type depth-integrating suspended-sediment samplers. These data indicate that the minimal duration of time averaging during standard field operation of depth-integrating samplers leads to an error that is comparable in magnitude to that arising from inadequate sampling of the cross-stream spatial structure in suspended-sediment concentration. This random error arising from inadequate time averaging is positively correlated with grain size and does not largely depend on flow conditions or, for a given size class of suspended sediment, on elevation above the bed. Averaging over time scales >1 minute is the likely minimum duration required

  5. Beyond long memory in heart rate variability: An approach based on fractionally integrated autoregressive moving average time series models with conditional heteroscedasticity

    Science.gov (United States)

    Leite, Argentina; Paula Rocha, Ana; Eduarda Silva, Maria

    2013-06-01

    Heart Rate Variability (HRV) series exhibit long memory and time-varying conditional variance. This work considers the Fractionally Integrated AutoRegressive Moving Average (ARFIMA) models with Generalized AutoRegressive Conditional Heteroscedastic (GARCH) errors. ARFIMA-GARCH models may be used to capture and remove long memory and estimate the conditional volatility in 24 h HRV recordings. The ARFIMA-GARCH approach is applied to fifteen long term HRV series available at Physionet, leading to the discrimination among normal individuals, heart failure patients, and patients with atrial fibrillation.

  6. Batch leachate treatment using stirred electrocoagulation reactor with variation of residence time and stirring rate

    Science.gov (United States)

    Sitorus, I. S.; Astono, W.; Iswanto, B.

    2018-01-01

    This study aims to reduce pollutant levels of the leachate by electrocoagulation method using a stirred electrocoagulation reactor as the electrochemical water treatment. The release of active coagulants as metallic ions took place in the anode, while in the cathode, the electrolysis reaction in the form of hydrogen gas dischargeoccurred. The source of wastewater is Waste Water Treatment Plant inlet III of Bantar Gebang, Bekasi. Some parameters were analyzed in this research, i.e., Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), NH3, NO3 -, NO2 -, N-total, and organic substances as well as the microorganism growth before and after electrocoagulation, with variations of detention time (seconds) of 10, 20, 120, 600 and rapid mixing conditions (rpm) of 60, 100 and 200. The results show that the greater the rapid mixing speed and the detention time of electrolysis, the higher the removal of contaminants in liquid waste. The optimum condition of electrocoagulation was encountered at 200 rpm rapid mixing with 600 seconds of processing time. The removal efficiencies of electrocoagulation method for each parameter are TSS of 46.80%, BOD5 of 71.33%, COD of 73.77%, Pb of 62.5%,and NH3-N of 57.92%,whereas the pH value has been increased from 8.03 to 8.95. The electrocoagulation method can reduce levels of pollutants, complying with the environmental standards.

  7. Can we differentiate alpine groundwater storages regarding volume and residence time by recession observations, ion composition and tracer balance?

    Science.gov (United States)

    Floriancic, Marius; Smoorenburg, Maarten; Margreth, Michael; Naef, Felix

    2015-04-01

    Research on how catchments store and release water is essential to improve flood and low flow prediction in (un)gauged watersheds. Despite their importance for catchment scale assessments on runoff generation, knowledge on storage properties and residence times is still limited. Here we present some approaches to separate different storage types regarding their residence time and a quantification of the volumes of these storages based on a dataset of winter recession observation in the alpine Poschiavino headwater area. This spatially highly resolved dataset of discharge, electric conductivity and ion composition from a watershed with strongly contrasting storage properties, allowed separating three main contributing sources: continuous discharge from bedrock cracks, strongly delayed discharge from thick sediment deposits and fractured rock and rapid discharge from shallow layers. The gradients of the recession curves, the variation of electric conductivity in the river network and calculated tracer balance were used to separate contribution from different sources. Additionally contribution from sedimentary rocks and crystalline layers could be separated based on the variation of ion composition in the water samples. We derived recession curves for a period of four months for the separated storages in different parts of the catchment allowing estimation of the contributed volumes in this time period. Finally the spatial distribution of the storage types could be mapped throughout the catchment based on information like geo(morpho)logical maps, aerial photographs, DEM and field observations. We found significant variation comparing the discharged volume and specific discharge throughout the winter season in the different subcatchments. Constant discharge from bedrock cracks is similar in all catchment parts. Storage in the shallow deposits depleted quickly. High winter discharge could be attributed to thick quaternary deposits contributing during the whole

  8. Use of the QR Reader to Provide Real-Time Evaluation of Residents' Skills Following Surgical Procedures.

    Science.gov (United States)

    Reynolds, Kellin; Barnhill, Danny; Sias, Jamie; Young, Amy; Polite, Florencia Greer

    2014-12-01

    A portable electronic method of providing instructional feedback and recording an evaluation of resident competency immediately following surgical procedures has not previously been documented in obstetrics and gynecology. This report presents a unique electronic format that documents resident competency and encourages verbal communication between faculty and residents immediately following operative procedures. The Microsoft Tag system and SurveyMonkey platform were linked by a 2-D QR code using Microsoft QR code generator. Each resident was given a unique code (TAG) embedded onto an ID card. An evaluation form was attached to each resident's file in SurveyMonkey. Postoperatively, supervising faculty scanned the resident's TAG with a smartphone and completed the brief evaluation using the phone's screen. The evaluation was reviewed with the resident and automatically submitted to the resident's educational file. The evaluation system was quickly accepted by residents and faculty. Of 43 residents and faculty in the study, 38 (88%) responded to a survey 8 weeks after institution of the electronic evaluation system. Thirty (79%) of the 38 indicated it was superior to the previously used handwritten format. The electronic system demonstrated improved utilization compared with paper evaluations, with a mean of 23 electronic evaluations submitted per resident during a 6-month period versus 14 paper assessments per resident during an earlier period of 6 months. This streamlined portable electronic evaluation is an effective tool for direct, formative feedback for residents, and it creates a longitudinal record of resident progress. Satisfaction with, and use of, this evaluation system was high.

  9. Linear and Nonlinear Time-Frequency Analysis for Parameter Estimation of Resident Space Objects

    Science.gov (United States)

    2017-02-22

    technical report is organised as follows: • In Section 2 Time-Frequency transforms are discussed and parameters of interests are identified. • In Section...NRMSE 0,206 0,292 0,428 %NRMSE 0,375 0,405 0,501 Table 5: table 4 continued The worst behaviour is obtained in the case of RSO 2. The reason behind...quantisation effect. On the other hand, the best behaviour is produced by RSO 1, whose Doppler frequency is the highest. By looking at tables 4 and 5, and not

  10. Motor current signature analysis for gearbox condition monitoring under transient speeds using wavelet analysis and dual-level time synchronous averaging

    Science.gov (United States)

    Bravo-Imaz, Inaki; Davari Ardakani, Hossein; Liu, Zongchang; García-Arribas, Alfredo; Arnaiz, Aitor; Lee, Jay

    2017-09-01

    This paper focuses on analyzing motor current signature for fault diagnosis of gearboxes operating under transient speed regimes. Two different strategies are evaluated, extensively tested and compared to analyze the motor current signature in order to implement a condition monitoring system for gearboxes in industrial machinery. A specially designed test bench is used, thoroughly monitored to fully characterize the experiments, in which gears in different health status are tested. The measured signals are analyzed using discrete wavelet decomposition, in different decomposition levels using a range of mother wavelets. Moreover, a dual-level time synchronous averaging analysis is performed on the same signal to compare the performance of the two methods. From both analyses, the relevant features of the signals are extracted and cataloged using a self-organizing map, which allows for an easy detection and classification of the diverse health states of the gears. The results demonstrate the effectiveness of both methods for diagnosing gearbox faults. A slightly better performance was observed for dual-level time synchronous averaging method. Based on the obtained results, the proposed methods can used as effective and reliable condition monitoring procedures for gearbox condition monitoring using only motor current signature.

  11. Recovery of Sleep or Recovery of Self? A Grounded Theory Study of Residents' Decision Making Regarding How to Spend Their Nonclinical Postcall Time.

    Science.gov (United States)

    Taylor, Taryn S; Nisker, Jeff; Teunissen, Pim W; Dornan, Tim; Lingard, Lorelei

    2016-03-01

    As resident work hours policies evolve, residents' off-duty time remains poorly understood. Despite assumptions about how residents should be using their postcall, off-duty time, there is little research on how residents actually use this time and the reasoning underpinning their activities. This study sought to understand residents' nonclinical postcall activities when they leave the hospital, their decision-making processes, and their perspectives on the relationship between these activities and their well-being or recovery. The study took place at a Liaison Committee on Medical Education-accredited Canadian medical school from 2012 to 2014. The authors recruited a purposive and convenience sample of postgraduate year 1-5 residents from six surgical and nonsurgical specialties at three hospitals affiliated with the medical school. Using a constructivist grounded theory approach, semistructured interviews were conducted, audio-taped, transcribed, anonymized, and combined with field notes. The authors analyzed interview transcripts using constant comparative analysis and performed post hoc member checking. Twenty-four residents participated. Residents characterized their predominant approach to postcall decision making as one of making trade-offs between multiple, competing, seemingly incompatible, but equally valuable, activities. Participants exhibited two different trade-off orientations: being oriented toward maintaining a normal life or toward mitigating fatigue. The authors' findings on residents' trade-off orientations suggest a dual recovery model with postcall trade-offs motivated by the recovery of sleep or of self. This model challenges the dominant viewpoint in the current duty hours literature and suggests that the duty hours discussion must be broadened to include other recovery processes.

  12. Moving Average Convergence Divergence filter preprocessing for real-time event-related peak activity onset detection : application to fNIRS signals.

    Science.gov (United States)

    Durantin, Gautier; Scannella, Sebastien; Gateau, Thibault; Delorme, Arnaud; Dehais, Frederic

    2014-01-01

    Real-time solutions for noise reduction and signal processing represent a central challenge for the development of Brain Computer Interfaces (BCI). In this paper, we introduce the Moving Average Convergence Divergence (MACD) filter, a tunable digital passband filter for online noise reduction and onset detection without preliminary learning phase, used in economic markets analysis. MACD performance was tested and benchmarked with other filters using data collected with functional Near Infrared Spectoscopy (fNIRS) during a digit sequence memorization task. This filter has a good performance on filtering and real-time peak activity onset detection, compared to other techniques. Therefore, MACD could be implemented for efficient BCI design using fNIRS.

  13. Particle image velocimetry-validated, computational fluid dynamics-based design to reduce shear stress and residence time in central venous hemodialysis catheters.

    Science.gov (United States)

    Mareels, Guy; Kaminsky, Radoslav; Eloot, Sunny; Verdonck, Pascal R

    2007-01-01

    As crucial factors in blood clot formation, shear stress distribution and low flow zones are assessed in different central venous catheter tip designs by using a combined numeric and experimental approach. Computational Fluid Dynamics was validated with Particle Image Velocimetry by comparing simulated and measured velocities and shear strains in three designs of the blood withdrawing arterial lumen: cylindrical and with tip (1) cut straight, (2) cut at an angle, or (3) cut straight with a sleeve entrance. After validation, four additional designs were studied: (4) with two side holes and tip cut straight or (5) at an angle, (6) concentric lumens, and (7) Ash Split-based. In these seven designs, shear stress (SS), blood residence time (RT), and Platelet Lysis Index, which combines the influence of shear stress magnitude and exposure time, were simulated. Concentric catheter was discarded due to highly elevated SS. Ash Split-based design had elevated RT values in the distal tip zone as major inflow occurs through the most proximal side holes, but this is compensated by low average SS. A straight-cut tip and possibly two side holes are preferred when aiming at minimal SS and RT. These data may lead to more patent catheters.

  14. Time course of cesium radionuclides body burden in residents of regions with elevated background radiation

    International Nuclear Information System (INIS)

    Vasil'ev, V.N.; Luchkov, A.B.; Trushin, V.I.; Khazins, E.D.

    1990-01-01

    The authors represent summarized data on the time course of 134 Cs and 137 Cs body burden in the population of the Krasnogorsky District of the Bryansk Region (Byelorussian SSR) over the period of June 1986-Jule 1989. A RISh-5M was used as a whole-body counter, its performance and calibration methods were described. A retrospective analysis has shown that the main accumulation of radionuclides occurred before May 15 1986. The highest half-life noted from August 1986 till Februal 1987. The ratio of accumulated Cs in children and adults was 0.3, in men and women - 1.4. The effectiveness of measures aimed at reducing collective doses of internal irradiation was analyzed

  15. Changing restoration rules: exotic bivalves interact with residence time and depth to control phytoplankton productivity

    Science.gov (United States)

    Lucas, Lisa V.; Thompson, Janet K.

    2012-01-01

    Non-native species are a prevalent ecosystem stressor that can interact with other stressors to confound resource management and restoration. We examine how interactions between physical habitat attributes and a particular category of non-native species (invasive bivalves) influence primary production in aquatic ecosystems. Using mathematical models, we show how intuitive relationships between phytoplankton productivity and controllable physical factors (water depth, hydraulic transport time) that hold in the absence of bivalves can be complicated—and even reversed—by rapid bivalve grazing. In light-limited environments without bivalves, shallow, hydrodynamically “slow” habitats should generally have greater phytoplankton biomass and productivity than deeper, “faster” habitats. But shallower, slower environments can be less productive than deeper, faster ones if benthic grazing is strong. Moreover, shallower and slower waters exhibit a particularly broad range of possible productivity outcomes that can depend on whether bivalves are present. Since it is difficult to predict the response of non-native bivalves to habitat restoration, outcomes for new shallow, slow environments can be highly uncertain. Habitat depth and transport time should therefore not be used as indicators of phytoplankton biomass and production where bivalve colonization is possible. This study provides for ecosystem management a particular example of a broad lesson: abiotic ecosystem stressors should be managed with explicit consideration of interactions with other major (including biotic) stressors. We discuss the applicability and management implications of our models and results for a range of aquatic system types, with a case study focused on the Sacramento-San Joaquin Delta (California, USA). Simple mathematical models like those used here can illuminate interactions between ecosystem stressors and provide process-based guidance for resource managers as they develop strategies

  16. Polymer binding to carbon nanotubes in aqueous dispersions: residence time on the nanotube surface as obtained by NMR diffusometry.

    Science.gov (United States)

    Frise, Anton E; Pagès, Guilhem; Shtein, Michael; Pri Bar, Ilan; Regev, Oren; Furó, István

    2012-03-08

    The binding of block copolymer Pluronic F-127 in aqueous dispersions of single- (SWCNT) and multiwalled (MWCNT) carbon nanotubes has been studied by pulsed-field-gradient (PFG) (1)H NMR spectroscopy. We show that a major fraction of polymers exist as a free species while a minor fraction is bound to the carbon nanotubes (CNT). The polymers exchange between these two states with residence times on the nanotube surface of 24 ± 5 ms for SWCNT and of 54 ± 11 ms for MWCNT. The CNT concentration in the solution was determined by improved thermal gravimetric analysis (TGA) indicating that the concentration of SWCNT dispersed by F-127 was significantly higher than that for MWCNT. For SWCNT, the area per adsorbed Pluronic F-127 molecule is estimated to be about 40 nm(2).

  17. Comparison of groundwater residence time using isotope techniques and numerical groundwater flow model in Gneissic Terrain, Korea

    International Nuclear Information System (INIS)

    Bae, D.S.; Kim, C.S.; Koh, Y.K.; Kim, K.S.; Song, M.Y.

    1997-01-01

    The prediction of groundwater flow affecting the migration of radionuclides is an important component of the performance assessment of radioactive waste disposal. Groundwater flow in fractured rock mass is controlled by fracture networks, transmissivity and hydraulic gradient. Furthermore the scale-dependent and anisotropic properties of hydraulic parameters are resulted mainly from irregular patterns of fracture system, which are very complex to evaluate properly with the current techniques available. For the purpose of characterizing a groundwater flow in fractured rock mass, the discrete fracture network (DFN) concept is available on the basis of assumptions of groundwater flowing only along fractures and flowpaths in rock mass formed by interconnected fractures. To increase the reliability of assessment in groundwater flow phenomena, numerical groundwater flow model and isotopic techniques were applied. Fracture mapping, borehole acoustic scanning were performed to identify conductive fractures in gneissic terrane. Tracer techniques, using deuterium, oxygen-18 and tritium were applied to evaluate the recharge area and groundwater residence time

  18. The effect of residence time on the tensile properties of superelastic and thermal activated Ni-Ti orthodontic wires

    Directory of Open Access Journals (Sweden)

    Kathia Maria Fosenca de Britto

    2011-09-01

    Full Text Available Since the 1980s, different devices based on superelastic alloys have been developed to fulfill orthodontic applications. Particularly in the last decades several researches have been carried out to evaluate the mechanical behavior of Ni-Ti alloys, including their tensile, torsion and fatigue properties. However, studies regarding the dependence of elastic properties on residence time of Ni-Ti wires in the oral cavity are scarce. Such approach is essential since metallic alloys are submitted to mechanical stresses during orthodontic treatment as well as pH and temperature fluctuations. The goal of the present contribution is to provide elastic stress-strain results to guide the orthodontic choice between martensitic thermal activated and austenitic superelastic Ni-Ti alloys. From the point of view of an orthodontist, the selection of appropriate materials and the correct maintenance of the orthodontic apparatus are essential needs during clinical treatment. The present work evaluated the elastic behavior of Ni-Ti alloy wires with diameters varying from 0.014 to 0.020 inches, submitted to hysteresis tensile tests with 8% strain. Tensile tests were performed after periods of use of 1, 2 and 3 months in the oral cavity of patients submitted to orthodontic treatment. The results from the hysteresis tests allowed to exam the strain range covered by isostress lines upon loading and unloading, as well as the residual strain after unloading for both superelastic and thermal activated Ni-Ti wires. Superelastic Ni-Ti wires exhibited higher load isostress values compared to thermal activated wires. It was found that such differences in the load isostress values can increase with increasing residence time.

  19. The decadal state of the terrestrial carbon cycle: Global retrievals of terrestrial carbon allocation, pools, and residence times.

    Science.gov (United States)

    Bloom, A Anthony; Exbrayat, Jean-François; van der Velde, Ivar R; Feng, Liang; Williams, Mathew

    2016-02-02

    The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle and its processes is, therefore, necessary to better understand its current state and predict its future state. We combine a diagnostic ecosystem carbon model with satellite observations of leaf area and biomass (where and when available) and soil carbon data to retrieve the first global estimates, to our knowledge, of carbon cycle state and process variables at a 1° × 1° resolution; retrieved variables are independent from the plant functional type and steady-state paradigms. Our results reveal global emergent relationships in the spatial distribution of key carbon cycle states and processes. Live biomass and dead organic carbon residence times exhibit contrasting spatial features (r = 0.3). Allocation to structural carbon is highest in the wet tropics (85-88%) in contrast to higher latitudes (73-82%), where allocation shifts toward photosynthetic carbon. Carbon use efficiency is lowest (0.42-0.44) in the wet tropics. We find an emergent global correlation between retrievals of leaf mass per leaf area and leaf lifespan (r = 0.64-0.80) that matches independent trait studies. We show that conventional land cover types cannot adequately describe the spatial variability of key carbon states and processes (multiple correlation median = 0.41). This mismatch has strong implications for the prediction of terrestrial carbon dynamics, which are currently based on globally applied parameters linked to land cover or plant functional types.

  20. The decadal state of the terrestrial carbon cycle: Global retrievals of terrestrial carbon allocation, pools, and residence times

    Science.gov (United States)

    Bloom, A. Anthony; Exbrayat, Jean-François; van der Velde, Ivar R.; Feng, Liang; Williams, Mathew

    2016-01-01

    The terrestrial carbon cycle is currently the least constrained component of the global carbon budget. Large uncertainties stem from a poor understanding of plant carbon allocation, stocks, residence times, and carbon use efficiency. Imposing observational constraints on the terrestrial carbon cycle and its processes is, therefore, necessary to better understand its current state and predict its future state. We combine a diagnostic ecosystem carbon model with satellite observations of leaf area and biomass (where and when available) and soil carbon data to retrieve the first global estimates, to our knowledge, of carbon cycle state and process variables at a 1° × 1° resolution; retrieved variables are independent from the plant functional type and steady-state paradigms. Our results reveal global emergent relationships in the spatial distribution of key carbon cycle states and processes. Live biomass and dead organic carbon residence times exhibit contrasting spatial features (r = 0.3). Allocation to structural carbon is highest in the wet tropics (85–88%) in contrast to higher latitudes (73–82%), where allocation shifts toward photosynthetic carbon. Carbon use efficiency is lowest (0.42–0.44) in the wet tropics. We find an emergent global correlation between retrievals of leaf mass per leaf area and leaf lifespan (r = 0.64–0.80) that matches independent trait studies. We show that conventional land cover types cannot adequately describe the spatial variability of key carbon states and processes (multiple correlation median = 0.41). This mismatch has strong implications for the prediction of terrestrial carbon dynamics, which are currently based on globally applied parameters linked to land cover or plant functional types. PMID:26787856

  1. How does warming affect carbon allocation, respiration and residence time in trees? An isotope tracer approach in a eucalypt

    Science.gov (United States)

    Pendall, E.; Drake, J. E.; Furze, M.; Barton, C. V.; Carillo, Y.; Richter, A.; Tjoelker, M. G.

    2017-12-01

    Climate warming has the potential to alter the balance between photosynthetic carbon assimilation and respiratory losses in forest trees, leading to uncertainty in predicting their future physiological functioning. In a previous experiment, warming decreased canopy CO2 assimilation (A) rates of Eucalyptus tereticornis trees, but respiration (R) rates were usually not significantly affected, due to physiological acclimation to temperature. This led to a slight increase in (R/A) and thus decrease in plant carbon use efficiency with climate warming. In contrast to carbon fluxes, the effect of warming on carbon allocation and residence time in trees has received less attention. We conducted a study to test the hypothesis that warming would decrease the allocation of C belowground owing to reduced cost of nutrient uptake. E. parramattensis trees were grown in the field in unique whole-tree chambers operated at ambient and ambient +3 °C temperature treatments (n=3 per treatment). We applied a 13CO2 pulse and followed the label in CO2 respired from leaves, roots, canopy and soil, in plant sugars, and in rhizosphere microbes over a 3-week period in conjunction with measurements of tree growth. The 9-m tall, 57 m3 whole-tree chambers were monitored for CO2 concentrations in independent canopy and below ground (root and soil) compartments; periodic monitoring of δ13C values in air in the compartments allowed us to quantify the amount of 13CO2 assimilated and respired by each tree. Warmed trees grew faster and assimilated more of the label than control trees, but the 13C allocation to canopy, root and soil respiration was not altered. However, warming appeared to reduce the residence time of carbon respired from leaves, and especially from roots and soil, indicating that autotrophic respiration has the potential to feedback to climate change. This experiment provides insights into how warming may affect the fate of assimilated carbon from the leaf to the ecosystem scale.

  2. Image-processing of time-averaged interface distributions representing CCFL characteristics in a large scale model of a PWR hot-leg pipe geometry

    International Nuclear Information System (INIS)

    Al Issa, Suleiman; Macián-Juan, Rafael

    2017-01-01

    Highlights: • CCFL characteristics are investigated in PWR large-scale hot-leg pipe geometry. • Image processing of air-water interface produced time-averaged interface distributions. • Time-averages provide a comparative method of CCFL characteristics among different studies. • CCFL correlations depend upon the range of investigated water delivery for Dh ≫ 50 mm. • 1D codes are incapable of investigating CCFL because of lack of interface distribution. - Abstract: Countercurrent Flow Limitation (CCFL) was experimentally investigated in a 1/3.9 downscaled COLLIDER facility with a 190 mm pipe’s diameter using air/water at 1 atmospheric pressure. Previous investigations provided knowledge over the onset of CCFL mechanisms. In current article, CCFL characteristics at the COLLIDER facility are measured and discussed along with time-averaged distributions of the air/water interface for a selected matrix of liquid/gas velocities. The article demonstrates the time-averaged interface as a useful method to identify CCFL characteristics at quasi-stationary flow conditions eliminating variations that appears in single images, and showing essential comparative flow features such as: the degree of restriction at the bend, the extension and the intensity of the two-phase mixing zones, and the average water level within the horizontal part and the steam generator. Consequently, making it possible to compare interface distributions obtained at different investigations. The distributions are also beneficial for CFD validations of CCFL as the instant chaotic gas/liquid interface is impossible to reproduce in CFD simulations. The current study shows that final CCFL characteristics curve (and the corresponding CCFL correlation) depends upon the covered measuring range of water delivery. It also shows that a hydraulic diameter should be sufficiently larger than 50 mm in order to obtain CCFL characteristics comparable to the 1:1 scale data (namely the UPTF data). Finally

  3. Idiopathic Sudden Sensorineural Hearing Loss: Average Time Elapsed Before Presentation to the Otolaryngologist and Effectiveness of Oral and/or Intratympanic Steroids in Late Presentations.

    Science.gov (United States)

    Anyah, Anwuli; Mistry, Devin; Kevern, Erin; Markiewicz, Kenneth

    2017-12-14

    Objectives To determine how long after symptom onset that the average patient with an idiopathic sudden sensorineural hearing loss (ISSNHL) presents to the otolaryngology clinic.  In late presentations, to determine the time to presentation cutoff after which intervention may not be effective.  To evaluate the effectiveness of oral steroids versus a combination of oral and intratympanic steroid therapy in late presentations of ISSNHL.  Methods and procedures Sixty-four patients met inclusion criteria after chart review of 2,037 patients seen at Metro Health Hospital from 2006 to 2016 for sensorineural hearing loss. All sixty-four patients were used to calculate the average time to presentation, but only 40 were included to evaluate treatment efficacy because 24 were lost to follow-up or declined treatment. Audiograms were analyzed for baseline status and response to treatment. Therapy was either oral steroids or intratympanic (IT) steroids. Thirty-nine of the 40 treated patients received oral steroid therapy. Eighteen of these 39 patients received both oral and IT steroids. One patient received IT steroids only.  Results For all 64 patients in the study, the average time to presentation was 55 days, ranging from one day to 240 days. Data for 32 of the 40 treated patients were analyzed. These patients were further divided into smaller groups: Group 1 (N = 11) - treatment within seven days of symptom onset, Group 2 (N = 17) - time to treatment greater than seven days but less than 90 days of symptom onset, and Group 3 (N = 4) - greater than 90 days of symptom onset. In Group 2, there was a significant improvement in pure tone average (P-value: 0.005). Forty-seven percent of patients in this group had objective treatment response utilizing Wilson's criteria. Two patients had a complete recovery and six had a partial recovery. Hearing gains ranged from 10 dB (decibels) to 23 dB. Sixty-three percent of patients with objective improvement also

  4. Family involvement in timely detection of changes in health of nursing homes residents: A qualitative exploratory study.

    Science.gov (United States)

    Powell, Catherine; Blighe, Alan; Froggatt, Katherine; McCormack, Brendan; Woodward-Carlton, Barbara; Young, John; Robinson, Louise; Downs, Murna

    2018-01-01

    To explore family perspectives on their involvement in the timely detection of changes in their relatives' health in UK nursing homes. Increasingly, policy attention is being paid to the need to reduce hospitalisations for conditions that, if detected and treated in time, could be managed in the community. We know that family continue to be involved in the care of their family members once they have moved into a nursing home. Little is known, however, about family involvement in the timely detection of changes in health in nursing home residents. Qualitative exploratory study with thematic analysis. A purposive sampling strategy was applied. Fourteen semi-structured one-to-one interviews with family members of people living in 13 different UK nursing homes. Data were collected from November 2015-March 2016. Families were involved in the timely detection of changes in health in three key ways: noticing signs of changes in health, informing care staff about what they noticed and educating care staff about their family members' changes in health. Families suggested they could be supported to detect timely changes in health by developing effective working practices with care staff. Families can provide a special contribution to the process of timely detection in nursing homes. Their involvement needs to be negotiated, better supported, as well as given more legitimacy and structure within the nursing home. Families could provide much needed support to nursing home nurses, care assistants and managers in timely detection of changes in health. This may be achieved through communication about their preferred involvement on a case-by-case basis as well as providing appropriate support or services. © 2017 The Authors. Journal of Clinical Nursing Published by John Wiley & Sons Ltd.

  5. Improving Timely Resident Follow-Up and Communication of Results in Ambulatory Clinics Utilizing a Web-Based Audit and Feedback Module.

    Science.gov (United States)

    Boggan, Joel C; Swaminathan, Aparna; Thomas, Samantha; Simel, David L; Zaas, Aimee K; Bae, Jonathan G

    2017-04-01

    Failure to follow up and communicate test results to patients in outpatient settings may lead to diagnostic and therapeutic delays. Residents are less likely than attending physicians to report results to patients, and may face additional barriers to reporting, given competing clinical responsibilities. This study aimed to improve the rates of communicating test results to patients in resident ambulatory clinics. We performed an internal medicine, residency-wide, pre- and postintervention, quality improvement project using audit and feedback. Residents performed audits of ambulatory patients requiring laboratory or radiologic testing by means of a shared online interface. The intervention consisted of an educational module viewed with initial audits, development of a personalized improvement plan after Phase 1, and repeated real-time feedback of individual relative performance compared at clinic and program levels. Outcomes included results communicated within 14 days and prespecified "significant" results communicated within 72 hours. A total of 76 of 86 eligible residents (88%) reviewed 1713 individual ambulatory patients' charts in Phase 1, and 73 residents (85%) reviewed 1509 charts in Phase 2. Follow-up rates were higher in Phase 2 than Phase 1 for communicating results within 14 days and significant results within 72 hours (85% versus 78%, P  audit and feedback quality improvement project can improve rates of resident follow-up and communication of results, although communication gaps remained.

  6. Effect of cheese on intestinal transit time and other indicators of bowel function in residents of a retirement home.

    Science.gov (United States)

    Mykkänen, H M; Karhunen, L J; Korpela, R; Salminen, S

    1994-01-01

    Effects of increased intake of cheese on intestinal transit time and other indicators of bowel function were studied in 21 retirement home residents (18 women and 3 men; age, 68-87 years). The study was divided into four succeeding periods: 1) 1-week basal period (usual diet); 2)3-week cheese period (extra cheese was offered as such on bread or used in cooking); 3) 3-week no-cheese period (all cheese on bread was replaced with cured meats and cold cuts, and no cheese was used in cooking); 4) 3-week follow-up period (usual diet). During the last week of each period a questionnaire was filled out on fecal frequencies, consistency of feces (soft, normal, hard), and occurrence of abdominal pain and flatulence. Use of laxative medications and therapeutic foods (prunes) was registered. Eleven of the 21 subjects collected fecal samples for the determination of fecal wet weight and intestinal transit time by means of radiopaque Sitzmark capsules. Intakes of cheese, fiber-containing foods, and fluids by these 11 subjects during meals offered in the cafeteria were recorded on a prefilled questionnaire. In spite of a 10-fold increase in the intake of cheese no change in intestinal transit time, fecal frequency, fecal wet weight, consistency of feces, and occurrence of gastrointestinal symptoms was observed. The use of laxative medication was higher during the cheese period, but no change in the combined use of laxative medication and therapeutic foods (prunes) was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Gasification of biomass wastes in an entrained flow gasifier: Effect of the particle size and the residence time

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, Juan J.; Aranda-Almansa, Guadalupe [Universidad de Castilla-La Mancha, Departamento de Mecanica Aplicada e Ingenieria de Proyectos, Escuela Tecnica Superior de Ingenieros Industriales (Edificio Politecnico), Avenida Camilo Jose Cela s/n, 13071 Ciudad Real (Spain); Bula, Antonio [Universidad del Norte, Departamento de Ingenieria Mecanica, Km.5 Antigua Via Puerto Colombia, Barranquilla (Colombia)

    2010-06-15

    Experimental tests in an entrained flow gasifier have been carried out in order to evaluate the effect of the biomass particle size and the space residence time on the gasifier performance and the producer gas quality. Three types of biomass fuels (grapevine pruning and sawdust wastes, and marc of grape) and a fossil fuel (a coal-coke blend) have been tested. The results obtained show that a reduction in the fuel particle size leads to a significant improvement in the gasification parameters. The thermochemical characterisation of the resulting char-ash residue shows a sharp increase in the fuel conversion for particles below 1 mm diameter, which could be adequate to be used in conventional entrained flow gasifiers. Significant differences in the thermochemical behaviour of the biomass fuels and the coal-coke blend have been found, especially in the evolution of the H{sub 2}/CO ratio with the space time, mainly due to the catalytic effect of the coal-coke ash. The reaction temperature and the space time have a significant effect on the H{sub 2}/CO ratio (the relative importance of each of these parameters depending on the temperature), this value being independent of the fuel particle size. (author)

  8. Time-averaged aerodynamic loads on the vane sets of the 40- by 80-foot and 80- by 120-foot wind tunnel complex

    Science.gov (United States)

    Aoyagi, Kiyoshi; Olson, Lawrence E.; Peterson, Randall L.; Yamauchi, Gloria K.; Ross, James C.; Norman, Thomas R.

    1987-01-01

    Time-averaged aerodynamic loads are estimated for each of the vane sets in the National Full-Scale Aerodynamic Complex (NFAC). The methods used to compute global and local loads are presented. Experimental inputs used to calculate these loads are based primarily on data obtained from tests conducted in the NFAC 1/10-Scale Vane-Set Test Facility and from tests conducted in the NFAC 1/50-Scale Facility. For those vane sets located directly downstream of either the 40- by 80-ft test section or the 80- by 120-ft test section, aerodynamic loads caused by the impingement of model-generated wake vortices and model-generated jet and propeller wakes are also estimated.

  9. Correlation between average frequency and RA value (rise time/amplitude) for crack classification of reinforced concrete beam using acoustic emission technique

    Science.gov (United States)

    Noorsuhada, M. N.; Abdul Hakeem, Z.; Soffian Noor, M. S.; Noor Syafeekha, M. S.; Azmi, I.

    2017-12-01

    Health monitoring of structures during their service life become a vital thing as it provides crucial information regarding the performance and condition of the structures. Acoustic emission (AE) is one of the non-destructive techniques (NDTs) that could be used to monitor the performance of the structures. Reinforced concrete (RC) beam associated with AE monitoring was monotonically loaded to failure under three-point loading. Correlation between average frequency and RA value (rise time / amplitude) was computed. The relationship was established to classify the crack types that propagated in the RC beam. The crack was classified as tensile crack and shear crack. It was found that the relationship is well matched with the actual crack pattern that appeared on the beam surface. Hence, this relationship is useful for prediction of the crack occurrence in the beam and its performance can be determined.

  10. Residence and transport time scales associated with Shatt Al-Arab discharges under various hydrological conditions estimated using a numerical model.

    Science.gov (United States)

    Alosairi, Yousef; Pokavanich, Tanuspong

    2017-05-15

    Over the last several decades, concerns in the Northwest Arabian Gulf have risen regarding water quality and ecological conditions, particularly near Kuwait. This interest is mainly attributed to the reduction of freshwater discharge and its associated constituents from the Shatt Al Arab as a result of human activities at diverse scales. From the hydrological perspective, the reduction has also resulted in alteration to the dynamic regime and related residence time and transport conditions. Using a previously well-validated three-dimensional numerical model of the Northern Arabian Gulf (NAG) (Alosairi and Pokavanich, 2017), the residence and transport conditions of numerical tracers have been assessed through a series of numerical tests. The results indicate that density-driven circulations have played a key role in reducing the residence time in the Northwest Gulf by approximately 15% to 20% compared to tidal forces only. The transport conditions correlated well with the Shatt Al Arab discharges, but they were only significant along the Kuwait coast due to counter-clockwise circulations and alongshore currents. Arrival times and mixing processes varied reasonably with the Shatt Al Arab discharges; the results exhibited the enhancement in mixing and transport with increases in discharge. Residence times in the NAG associated with Shatt Al Arab discharge displayed spatial variations, particularly in Kuwait Bay, where the residence time increased by 60days during low discharge compared to high discharge. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Quantifying the residence time and flushing characteristics of a shallow, back-barrier estuary: Application of hydrodynamic and particle tracking models

    Science.gov (United States)

    Defne, Zafer; Ganju, Neil K.

    2015-01-01

    Estuarine residence time is a major driver of eutrophication and water quality. Barnegat Bay-Little Egg Harbor (BB-LEH), New Jersey, is a lagoonal back-barrier estuary that is subject to anthropogenic pressures including nutrient loading, eutrophication, and subsequent declines in water quality. A combination of hydrodynamic and particle tracking modeling was used to identify the mechanisms controlling flushing, residence time, and spatial variability of particle retention. The models demonstrated a pronounced northward subtidal flow from Little Egg Inlet in the south to Pt. Pleasant Canal in the north due to frictional effects in the inlets, leading to better flushing of the southern half of the estuary and particle retention in the northern estuary. Mean residence time for BB-LEH was 13 days but spatial variability was between ∼0 and 30 days depending on the initial particle location. Mean residence time with tidal forcing alone was 24 days (spatial variability between ∼0 and 50 days); the tides were relatively inefficient in flushing the northern end of the Bay. Scenarios with successive exclusion of physical processes from the models revealed that meteorological and remote offshore forcing were stronger drivers of exchange than riverine inflow. Investigations of water quality and eutrophication should take into account spatial variability in hydrodynamics and residence time in order to better quantify the roles of nutrient loading, production, and flushing.

  12. Use of isotopic and geochemical tracers to identify source waters, flow paths, and residence times of headwater catchments in Boulder Creek Watershed, Colorado

    Science.gov (United States)

    Cowie, R. M.; Williams, M. W.; Atkins, P. T.

    2009-12-01

    An outstanding question for snowmelt-dominated watersheds of the western US is the response of stream flow to changes in climate. We know little about mountain aquifers because they commonly involve structurally complicated rocks, extreme head gradients (ground slope angles 10-40°), and dramatically fluctuating recharge due to seasonal snow-melt. In general, the western United States is predicted to face warmer temperatures and more frequent and prolonged droughts, and we can expect to see a decrease in annual snowpack, earlier onset of snowmelt, and increased evaporation. Understanding streamflow generation under these climatic conditions will become increasingly important as hydrologic inputs change drastically and outputs are increasingly needed for human consumption. To improve our understanding of surface/groundwater interactions, we are simultaneously collecting surface water, subsurface, and precipitation samples at four gauged headwater catchments along a 1,500-m elevational gradient in the Boulder Creek Critical Zone Observatory: (1) Green Lakes Valley (3,500 m); (2) Como Creek (2,900 m); (3) Gordon Gulch (2,400 m); and Betasso (1,830 m). All water samples are analyzed for geochemical and isotopic (δ18O, δD) composition. The average residence time for subsurface flow is calculated by comparing the smoothing of the δ18O input (precipitation) and output (streamflow) using a convolution algorithm. The calculation of residence times is also constrained by measuring concentrations of tritium (3H), a naturally occurring radioisotope, to better understand sub-surface transit times. A two-component mixing model will be used to determine source waters from old (reacted) waters and new (unreacted) waters. End member mixing analysis (EMMA) is a statistically unbiased technique that will also be used to identify the most important end members contributing to stream flow. The application of Principle Component Analysis (PCA) using all of the isotopic and

  13. Budget and residence time of {sup 210}Pb along the Gulf of Lion`s continental slope (Northwestern Mediterranean Sea)

    Energy Technology Data Exchange (ETDEWEB)

    Abassi, A.; Radakovitch, O.; Heussner, S.; Monaco, A. [Perpignan Univ., 66 (France). Lab. de Sedimentologie et Geochimie Marines

    1997-12-31

    Concentration of {sup 210}Pb has been measured in water and sediment trap samples collected on 7 experimental sites representative of the Gulf of Lion`s continental margin. This marine system is characterised by a major continental input through the Rhone river and a powerful along-slope cyclonic current (Northern Current). From the distribution of bulk {sup 210}Pb activities, it was intended to gain some information on the processes controlling the transport of trace metals at the ocean/continent boundary. Residence times of {sup 210}Pb relative to scavenging in surface waters (0-100 m) showed a constant along-slope (i.e., downstream) decrease that can be related to increasing concentrations in suspended particles. Annual time-series of {sup 210}Pb activities in settling particles were determined on samples collected by traps at 500 and 1000 m depth. From this data set, a budget for {sup 210}Pb on this margin was established which permitted to determine the flux of {sup 210}Pb theoretically adsorbed onto particles. This theoretical flux was compared, at each site, with fluxes effectively measured by traps and revealed that exchange processes - mainly in the form of large inputs of this nuclide (import of 47 to 93% of measured flux) - largely affect the {sup 210}Pb distribution on this continental margin. (author) 12 refs.

  14. Budget and residence time of 210Pb along the Gulf of Lion's continental slope (Northwestern Mediterranean Sea)

    International Nuclear Information System (INIS)

    Abassi, A.; Radakovitch, O.; Heussner, S.; Monaco, A.

    1997-01-01

    Concentration of 210 Pb has been measured in water and sediment trap samples collected on 7 experimental sites representative of the Gulf of Lion's continental margin. This marine system is characterised by a major continental input through the Rhone river and a powerful along-slope cyclonic current (Northern Current). From the distribution of bulk 210 Pb activities, it was intended to gain some information on the processes controlling the transport of trace metals at the ocean/continent boundary. Residence times of 210 Pb relative to scavenging in surface waters (0-100 m) showed a constant along-slope (i.e., downstream) decrease that can be related to increasing concentrations in suspended particles. Annual time-series of 210 Pb activities in settling particles were determined on samples collected by traps at 500 and 1000 m depth. From this data set, a budget for 210 Pb on this margin was established which permitted to determine the flux of 210 Pb theoretically adsorbed onto particles. This theoretical flux was compared, at each site, with fluxes effectively measured by traps and revealed that exchange processes - mainly in the form of large inputs of this nuclide (import of 47 to 93% of measured flux) - largely affect the 210 Pb distribution on this continental margin. (author)

  15. The role of exposure time in computerized training of prostate cryosurgery: performance comparison of surgical residents with engineering students.

    Science.gov (United States)

    Joshi, Purva; Sehrawat, Anjali; Rabin, Yoed

    2018-04-01

    This study aims at the evaluation of a prototype of a computerized trainer for cryosurgery-the controlled destruction of cancer tumors by freezing. The hypothesis in this study is that computer-based cryosurgery training for an optimal cryoprobe layout is essentially a matter of exposure time, rather than trainee background or the specific computer-generated planning target. Key geometric features under considerations are associated with spatial limitations on cryoprobes placement and the match between the resulted thermal field and the unique anatomy of the prostate. All experiments in this study were performed on the cryosurgery trainer-a prototype platform for computerized cryosurgery training, which has been presented previously. Among its key features, the cryosurgery trainer displays the prostate shape and its contours and provides a distance measurement tool on demand, in order to address spatial constraints during ultrasound imaging guidance. Another unique feature of the cryosurgery trainer is an output movie, displaying the simulated thermal field at the end of the cryoprocedure. The current study was performed on graduate engineering students having no formal background in medicine, and the results were benchmarked against data obtained on surgical residents having no experience with cryosurgery. Despite fundamental differences in background and experience, neither group displayed superior performance when it comes to cryoprobe layout planning. This study demonstrates that computer-based training of an optimal cryoprobe layout is feasible. This study demonstrates that the training quality is essentially related to the training exposure time, rather than to a specific planning strategy from those investigated.

  16. Method for sampling and analysis of volatile biomarkers in process gas from aerobic digestion of poultry carcasses using time-weighted average SPME and GC-MS.

    Science.gov (United States)

    Koziel, Jacek A; Nguyen, Lam T; Glanville, Thomas D; Ahn, Heekwon; Frana, Timothy S; Hans van Leeuwen, J

    2017-10-01

    A passive sampling method, using retracted solid-phase microextraction (SPME) - gas chromatography-mass spectrometry and time-weighted averaging, was developed and validated for tracking marker volatile organic compounds (VOCs) emitted during aerobic digestion of biohazardous animal tissue. The retracted SPME configuration protects the fragile fiber from buffeting by the process gas stream, and it requires less equipment and is potentially more biosecure than conventional active sampling methods. VOC concentrations predicted via a model based on Fick's first law of diffusion were within 6.6-12.3% of experimentally controlled values after accounting for VOC adsorption to the SPME fiber housing. Method detection limits for five marker VOCs ranged from 0.70 to 8.44ppbv and were statistically equivalent (p>0.05) to those for active sorbent-tube-based sampling. The sampling time of 30min and fiber retraction of 5mm were found to be optimal for the tissue digestion process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Average-energy games

    Directory of Open Access Journals (Sweden)

    Patricia Bouyer

    2015-09-01

    Full Text Available Two-player quantitative zero-sum games provide a natural framework to synthesize controllers with performance guarantees for reactive systems within an uncontrollable environment. Classical settings include mean-payoff games, where the objective is to optimize the long-run average gain per action, and energy games, where the system has to avoid running out of energy. We study average-energy games, where the goal is to optimize the long-run average of the accumulated energy. We show that this objective arises naturally in several applications, and that it yields interesting connections with previous concepts in the literature. We prove that deciding the winner in such games is in NP inter coNP and at least as hard as solving mean-payoff games, and we establish that memoryless strategies suffice to win. We also consider the case where the system has to minimize the average-energy while maintaining the accumulated energy within predefined bounds at all times: this corresponds to operating with a finite-capacity storage for energy. We give results for one-player and two-player games, and establish complexity bounds and memory requirements.

  18. Groundwater residence time and aquifer recharge in mutilayered, semi-confined and faulted aquifer systems using environmental tracers

    Science.gov (United States)

    Batlle-Aguilar, J.; Banks, E.; Batelaan, O.; Kipfer, R.; Brennwald, M. S.; Cook, P. G.

    2016-12-01

    Population growth and ongoing climate change threatens the future of water supply in many regions. Therefore water resources need to be managed in a way such that water demands for industrial, agricultural, recreation and household uses are met in a sustainable approach. To do so, appropriate knowledge of groundwater residence time and aquifer recharge is paramount. But populations are largely concentrated on sedimentary basins where aquifers are often multi-layered, semi-confined and faulted, challenging the study of groundwater flow processes. The motivation of this work is to study the potential of environmental tracers (δ18O, δ2H, δ13C, 14C, 4He, 20Ne, 40Ar, N2) to assist our understanding of recharge processes and residence times in semi-confined, multilayered and faulted aquifer systems. For that purpose, the coastal aquifer system in the Adelaide Plains basin, South Australia, was studied. Carbon-14 groundwater ages were found to increase with depth and distance (30,000 years near the coast), confirming the system is semi-confined and the palaeometeoric origin of groundwater, as suggested by water stable isotopes. The presence of old groundwater near the top of deep semi-confined aquifers suggested that recharge mainly occurs in the mountain ranges east of the basin, a finding which was supported by higher Cl concentrations in the overlying Quaternary aquifers. Mean groundwater flow velocity of 0.8 m y-1 was estimated using 14C ages, and confirmed with 4He estimations. However 4He accumulation rates ranging between 8×10-12 and 1×10-10 cm3 STP g-1 y-1 and 1.7-7.1×10-7 cm3 STP g-1 km-1 confirmed slower flow velocities in some areas, velocities that could not be captured using 14C. Faults were found to play a paramount role in mixing old fluids rich in salts and 4He, but it was not possible to demonstrate the role of faults in changing flow velocities, which requires a higher density of sampling points. Our study shows that environmental tracers are a

  19. Quantification of benzene, toluene, ethylbenzene and o-xylene in internal combustion engine exhaust with time-weighted average solid phase microextraction and gas chromatography mass spectrometry.

    Science.gov (United States)

    Baimatova, Nassiba; Koziel, Jacek A; Kenessov, Bulat

    2015-05-11

    A new and simple method for benzene, toluene, ethylbenzene and o-xylene (BTEX) quantification in vehicle exhaust was developed based on diffusion-controlled extraction onto a retracted solid-phase microextraction (SPME) fiber coating. The rationale was to develop a method based on existing and proven SPME technology that is feasible for field adaptation in developing countries. Passive sampling with SPME fiber retracted into the needle extracted nearly two orders of magnitude less mass (n) compared with exposed fiber (outside of needle) and sampling was in a time weighted-averaging (TWA) mode. Both the sampling time (t) and fiber retraction depth (Z) were adjusted to quantify a wider range of Cgas. Extraction and quantification is conducted in a non-equilibrium mode. Effects of Cgas, t, Z and T were tested. In addition, contribution of n extracted by metallic surfaces of needle assembly without SPME coating was studied. Effects of sample storage time on n loss was studied. Retracted TWA-SPME extractions followed the theoretical model. Extracted n of BTEX was proportional to Cgas, t, Dg, T and inversely proportional to Z. Method detection limits were 1.8, 2.7, 2.1 and 5.2 mg m(-3) (0.51, 0.83, 0.66 and 1.62 ppm) for BTEX, respectively. The contribution of extraction onto metallic surfaces was reproducible and influenced by Cgas and t and less so by T and by the Z. The new method was applied to measure BTEX in the exhaust gas of a Ford Crown Victoria 1995 and compared with a whole gas and direct injection method. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Rational optimization of drug-target residence time: Insights from inhibitor binding to the S. aureus FabI enzyme-product complex

    Science.gov (United States)

    Chang, Andrew; Schiebel, Johannes; Yu, Weixuan; Bommineni, Gopal R.; Pan, Pan; Baxter, Michael V.; Khanna, Avinash; Sotriffer, Christoph A.; Kisker, Caroline; Tonge, Peter J.

    2013-01-01

    Drug-target kinetics has recently emerged as an especially important facet of the drug discovery process. In particular, prolonged drug-target residence times may confer enhanced efficacy and selectivity in the open in vivo system. However, the lack of accurate kinetic and structural data for series of congeneric compounds hinders the rational design of inhibitors with decreased off-rates. Therefore, we chose the Staphylococcus aureus enoyl-ACP reductase (saFabI) - an important target for the development of new anti-staphylococcal drugs - as a model system to rationalize and optimize the drug-target residence time on a structural basis. Using our new, efficient and widely applicable mechanistically informed kinetic approach, we obtained a full characterization of saFabI inhibition by a series of 20 diphenyl ethers complemented by a collection of 9 saFabI-inhibitor crystal structures. We identified a strong correlation between the affinities of the investigated saFabI diphenyl ether inhibitors and their corresponding residence times, which can be rationalized on a structural basis. Due to its favorable interactions with the enzyme, the residence time of our most potent compound exceeds 10 hours. In addition, we found that affinity and residence time in this system can be significantly enhanced by modifications predictable by a careful consideration of catalysis. Our study provides a blueprint for investigating and prolonging drug-target kinetics and may aid in the rational design of long-residence-time inhibitors targeting the essential saFabI enzyme. PMID:23697754

  1. Residency training program: Perceptions of residents

    African Journals Online (AJOL)

    This study was carried out to ascertain the perception of the residency ... the time of the study. Analysis of the respondents showed similar findings for both senior and junior levels of training. Discussion. The introduction of the residency training program .... Overseas training/ attachment should be re-introduced. 12. (10.1).

  2. Fast prediction of pulsed nonlinear acoustic fields from clinically relevant sources using time-averaged wave envelope approach: comparison of numerical simulations and experimental results.

    Science.gov (United States)

    Wójcik, J; Kujawska, T; Nowicki, A; Lewin, P A

    2008-12-01

    The primary goal of this work was to verify experimentally the applicability of the recently introduced time-averaged wave envelope (TAWE) method [J. Wójcik, A. Nowicki, P.A. Lewin, P.E. Bloomfield, T. Kujawska, L. Filipczyński, Wave envelopes method for description of nonlinear acoustic wave propagation, Ultrasonics 44 (2006) 310-329.] as a tool for fast prediction of four dimensional (4D) pulsed nonlinear pressure fields from arbitrarily shaped acoustic sources in attenuating media. The experiments were performed in water at the fundamental frequency of 2.8 MHz for spherically focused (focal length F=80 mm) square (20 x 20 mm) and rectangular (10 x 25mm) sources similar to those used in the design of 1D linear arrays operating with ultrasonic imaging systems. The experimental results obtained with 10-cycle tone bursts at three different excitation levels corresponding to linear, moderately nonlinear and highly nonlinear propagation conditions (0.045, 0.225 and 0.45 MPa on-source pressure amplitude, respectively) were compared with those yielded using the TAWE approach [J. Wójcik, A. Nowicki, P.A. Lewin, P.E. Bloomfield, T. Kujawska, L. Filipczyński, Wave envelopes method for description of nonlinear acoustic wave propagation, Ultrasonics 44 (2006) 310-329.]. The comparison of the experimental results and numerical simulations has shown that the TAWE approach is well suited to predict (to within+/-1 dB) both the spatial-temporal and spatial-spectral pressure variations in the pulsed nonlinear acoustic beams. The obtained results indicated that implementation of the TAWE approach enabled shortening of computation time in comparison with the time needed for prediction of the full 4D pulsed nonlinear acoustic fields using a conventional (Fourier-series) approach [P.T. Christopher, K.J. Parker, New approaches to nonlinear diffractive field propagation, J. Acoust. Soc. Am. 90 (1) (1991) 488-499.]. The reduction in computation time depends on several parameters

  3. Pregnancy and the Plastic Surgery Resident.

    Science.gov (United States)

    Garza, Rebecca M; Weston, Jane S; Furnas, Heather J

    2017-01-01

    Combining pregnancy with plastic surgery residency has historically been difficult. Two decades ago, 36 percent of plastic surgery program directors surveyed actively discouraged pregnancy among residents, and 33 percent of women plastic surgeons suffered from infertility. Most alarmingly, 26 percent of plastic surgery trainees had had an elective abortion during residency. With increasing numbers of women training in plastic surgery, this historical lack of support for pregnancy deserves further attention. To explore the current accommodations made for the pregnant plastic surgery resident, an electronic survey was sent to 88 plastic surgery program directors in the United States. Fifty-four responded, for a response rate of 61.36 percent. On average, a director trained a total of 7.91 women among 17.28 residents trained over 8.19 years. Of the women residents, 1.43 were pregnant during a director's tenure, with 1.35 of those residents taking maternity leave. An average 1.75 male residents took paternity leave. Approximately one-third of programs had a formal maternity/paternity leave policy (36.54 percent) which, in most cases, was limited to defining allowed weeks of leave, time required to fulfill program requirements, and remuneration during leave. This survey of plastic surgery directors is a first step in defining the challenges training programs face in supporting the pregnant resident. Directors provided comments describing their challenges accommodating an absent resident in a small program and complying with the American Board of Plastic Surgery's required weeks of training per year. A discussion of these challenges is followed by suggested solutions.

  4. Effects of first-pass metabolism on metabolite mean residence time determination after oral administration of parent drug.

    Science.gov (United States)

    Chan, K K; Gibaldi, M

    1990-01-01

    Metabolite kinetics after oral drug administration can be determined, without separate metabolite administration, using the concepts of mean residence time (MRT). The MRT of parent drug and metabolite after oral administration of the parent drug, MRTp,p(oral) and MRTm,p(oral), can be calculated directly from the drug and metabolite profiles. The difference between MRTm,p(oral) and MRTp,p(oral), termed Delta MRT, yields an estimate of MRT of metabolite when the metabolite is given as an iv bolus, MRTm,m(iv). The calculation is simple for drugs that are known to undergo, negligible first-pass metabolism. Correction can also be made when extent of first-pass metabolism is known. Ambiguity is encountered, however, when the degree of first-pass metabolism is unknown. When the delta MRT is negative, then first-pass metabolism must be considered. A positive value of delta MRT, on the other hand, is not a definitive indication of the absence of first-pass metabolism. It may occur in the presence or absence of first-pass metabolism. Ignoring the possibility of first-pass metabolism when a positive value of delta MRT occurs may lead to an incorrect estimate of MRTm,m(iv). The estimation error is relatively small, however, when MRTm,m(iv) much greater than MRTp,p(iv), even when first-pass metabolism is extensive. This situation may apply to the administration of a prodrug.

  5. Denitrification in a low-temperature bioreactor system at two different hydraulic residence times: laboratory column studies.

    Science.gov (United States)

    Nordström, Albin; Herbert, Roger B

    2017-06-01

    Nitrate removal rates in a mixture of pine woodchips and sewage sludge were determined in laboratory column studies at 5°C, 12°C, and 22°C, and at two different hydraulic residence times (HRTs; 58.2-64.0 hours and 18.7-20.6 hours). Baffles installed in the flow path were tested as a measure to reduce preferential flow behavior, and to increase the nitrate removal in the columns. The nitrate removal in the columns was simulated at 5°C and 12°C using a combined Arrhenius-Monod equation controlling the removal rate, and a first-order exchange model for incorporation of stagnant zones. Denitrification in the mixture of pine woodchips and sewage sludge reduced nitrate concentrations of 30 mg N L -1 at 5°C to below detection limits at a HRT of 58.2-64.0 hours. At a HRT of 18.7-20.6 hours, nitrate removal was incomplete. The Arrhenius frequency factor and activation energy retrieved from the low HRT data supported a biochemically controlled reaction rate; the same parameters, however, could not be used to simulate the nitrate removal at high HRT. The results show an inversely proportional relationship between the advection velocity and the nitrate removal rate, suggesting that bioreactor performance could be enhanced by promoting low advection velocities.

  6. Charge and energy dependence of the residence time of cosmic ray nuclei below 15 GeV/nucleon

    International Nuclear Information System (INIS)

    Soutoul, A.; Engelmann, J.J.; Ferrando, P.; Koch-Miramond, L.; Masse, P.; Webber, W.R.

    1985-01-01

    The relative abundance of nuclear species measured in cosmic rays at Earth has often been interpreted with the simple leaky box model. For this model to be consistent an essential requirement is that the escape length does not depend on the nuclear species. The discrepancy between escape length values derived from iron secondaries and from the B/C ratio was identified by Garcia-Munoz and his co-workers using a large amount of experimental data. Ormes and Protheroe found a similar trend in the HEAO data although they questioned its significance against uncertainties. They also showed that the change in the B/C ratio values implies a decrease of the residence time of cosmic rays at low energies in conflict with the diffusive convective picture. These conclusions crucially depend on the partial cross section values and their uncertainties. Recently new accurate cross sections of key importance for propagation calculations have been measured. Their statistical uncertainties are often better than 4% and their values significantly different from those previously accepted. Here, these new cross sections are used to compare the observed B/C+O and (Sc to Cr)/Fe ratio to those predicted with the simple leaky box model

  7. Rapid generation of volatile fatty acids (VFA) through anaerobic acidification of livestock organic waste at low hydraulic residence time (HRT).

    Science.gov (United States)

    Kuruti, Kranti; Nakkasunchi, Shalini; Begum, Sameena; Juntupally, Sudharshan; Arelli, Vijayalakshmi; Anupoju, Gangagni Rao

    2017-08-01

    The purpose of this study was to investigate the effect of pre-treatment and F/M (Food to Microorganism) ratios for the rapid generation of volatile fatty acids (VFA) from livestock organic wastes (cattle manure (CM) and poultry litter (PL)) through an anaerobic acidification process at a pH range of 4.5-5.5. Experiments were organized using CM and PL in batch reactors (1L and 25L) with and with no pre-treatment of substrate at F/M ratios (0.4, 0.6, 0.8 and 1). Among various existing pre-treatments methods, thermal-acidic (120°C; 1% H 2 SO 4 ) pre-treatment was found effective. The results revealed that 0.31 and 0.47kg VFA/(kg VS reduced) could be obtained from CM and PL respectively with no pre-treatment, whereas it improvised to 0.43 and 0.67kg VFA/(kg VS reduced) correspondingly due to pre-treatment. Aforesaid, better yield of VFA was obtained at F/M ratio of 1.0, pH-5.5 and hydraulic residence time of 4days. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Performance linked to residence time distribution by a novel wool-based bioreactor for tertiary sewage treatment.

    Science.gov (United States)

    Hu, Bibo; Wheatley, Andrew; Ishtchenko, Vera; Huddersman, Katherine

    2012-05-01

    Laboratory-scale experiments were carried out using up-flow 7 L Submerged Aerated Filter reactors packed with wool fibre or commercial plastic pall rings, Kaldnes, (70% by volume) support media for the tertiary treatment of sewage. The performance of the wool bioreactor was more consistent than that with Kaldnes medium, for both TOC removal (93%) and SS removal (90%). Both plastic and wool-packed bioreactors achieved complete nitrification at the load of about 0.4 kgCOD/m(3)/day. The sludge yield of the wool bioreactor was almost half that of the bioreactor with Kaldnes suggesting that wool could retain residual organics and particulates. The wool however was degraded and it was concluded that wool would have to be considered as additional sacrificial adsorption capacity rather than an alternative medium. The performance was linked to the residence time distribution studies and these changes in the wool structure. Biomass growth increased the retention of the tracer in the wool reactor by, it was suggested, exposing a greater surface area. Results from the plastic media on the other hand showed increased mixing possibly by increasing the mobility of the plastic. Aeration increased the mixing in both reactors, and patterns were in all cases predominantly well-mixed.

  9. Contrasting residence times and fluxes of water and sulfate in two small forested watersheds in Virginia, USA.

    Science.gov (United States)

    Böhlke, John Karl; Michel, Robert L

    2009-07-01

    Watershed mass balances for solutes of atmospheric origin may be complicated by the residence times of water and solutes at various time scales. In two small forested headwater catchments in the Appalachian Mountains of Virginia, USA, mean annual export rates of SO(4)(=) differ by a factor of 2, and seasonal variations in SO(4)(=) concentrations in atmospheric deposition and stream water are out of phase. These features were investigated by comparing (3)H, (35)S, delta(34)S, delta(2)H, delta(18)O, delta(3)He, CFC-12, SF(6), and chemical analyses of open deposition, throughfall, stream water, and spring water. The concentrations of SO(4)(=) and radioactive (35)S were about twice as high in throughfall as in open deposition, but the weighted composite values of (35)S/S (11.1 and 12.1x10(-15)) and delta(34)S (+3.8 and +4.1 per thousand) were similar. In both streams (Shelter Run, Mill Run), (3)H concentrations and delta(34)S values during high flow were similar to those of modern deposition, delta(2)H and delta(18)O values exhibited damped seasonal variations, and (35)S/S ratios (0-3x10(-15)) were low throughout the year, indicating inter-seasonal to inter-annual storage and release of atmospheric SO(4)(=) in both watersheds. In the Mill Run watershed, (3)H concentrations in stream base flow (10-13 TU) were consistent with relatively young groundwater discharge, most delta(34)S values were approximately the same as the modern atmospheric deposition values, and the annual export rate of SO(4)(=) was equal to or slightly greater than the modern deposition rate. In the Shelter Run watershed, (3)H concentrations in stream base flow (1-3 TU) indicate that much of the discharging ground water had been deposited prior to the onset of atmospheric nuclear bomb testing in the 1950s, base flow delta(34)S values (+1.6 per thousand) were significantly lower than the modern deposition values, and the annual export rate of SO(4)(=) was less than the modern deposition rate

  10. Time-averaged probability density functions of soot nanoparticles along the centerline of a piloted turbulent diffusion flame using a scanning mobility particle sizer

    KAUST Repository

    Chowdhury, Snehaunshu

    2017-01-23

    In this study, we demonstrate the use of a scanning mobility particle sizer (SMPS) as an effective tool to measure the probability density functions (PDFs) of soot nanoparticles in turbulent flames. Time-averaged soot PDFs necessary for validating existing soot models are reported at intervals of ∆x/D∆x/D = 5 along the centerline of turbulent, non-premixed, C2H4/N2 flames. The jet exit Reynolds numbers of the flames investigated were 10,000 and 20,000. A simplified burner geometry based on a published design was chosen to aid modelers. Soot was sampled directly from the flame using a sampling probe with a 0.5-mm diameter orifice and diluted with N2 by a two-stage dilution process. The overall dilution ratio was not evaluated. An SMPS system was used to analyze soot particle concentrations in the diluted samples. Sampling conditions were optimized over a wide range of dilution ratios to eliminate the effect of agglomeration in the sampling probe. Two differential mobility analyzers (DMAs) with different size ranges were used separately in the SMPS measurements to characterize the entire size range of particles. In both flames, the PDFs were found to be mono-modal in nature near the jet exit. Further downstream, the profiles were flatter with a fall-off at larger particle diameters. The geometric mean of the soot size distributions was less than 10 nm for all cases and increased monotonically with axial distance in both flames.

  11. Time-averaged simulated microgravity (taSMG) inhibits proliferation of lymphoma cells, L-540 and HDLM-2, using a 3D clinostat.

    Science.gov (United States)

    Kim, Yoon Jae; Jeong, Ae Jin; Kim, Myungjoon; Lee, Chiwon; Ye, Sang-Kyu; Kim, Sungwan

    2017-04-20

    Gravity is omnipresent on Earth; however, humans in space, such as astronauts at the International Space Station, experience microgravity. Long-term exposure to microgravity is considered to elicit physiological changes, such as muscle atrophy, in the human body. In addition, certain types of cancer cells demonstrate inhibited proliferation under condition of time-averaged simulated microgravity (taSMG). However, the response of human Hodgkin's lymphoma cancer cells to reduced gravity, and the associated physiological changes in these cells, have not been elucidated. In this study, the proliferation of human Hodgkin's lymphoma cancer cells (L-540 and HDLM-2) under taSMG condition (motors were used to actuate the frames. Electrical wires for power supply and communication were connected via slip ring. For symmetrical path of gravitational vector, optimal angular velocities of the motors were found using simulation results. Under the condition of taSMG implemented by the 3D clinostat, proliferation of the cells was observed for 3 days. The results indicated that proliferation of these cancer cells was significantly (p < 0.0005) inhibited under taSMG, whereas proliferation of normal HDF cells was not affected. Findings in this study could be significantly valuable in developing novel strategies for selective killing of cancer cells such as lymphoma.

  12. Use of multiple age tracers to estimate groundwater residence times and long-term recharge rates in arid southern Oman

    Science.gov (United States)

    Müller, Th.; Osenbrück, K.; Strauch, G.; Pavetich, S.; Al-Mashaikhi, K.-S.; Herb, C.; Merchel, S.; Rugel, G.; Aeschbach, W.; Sanford, Ward E.

    2016-01-01

    Multiple age tracers were measured to estimate groundwater residence times in the regional aquifer system underlying southwestern Oman. This area, known as the Najd, is one of the most arid areas in the world and is planned to be the main agricultural center of the Sultanate of Oman in the near future. The three isotopic age tracers 4He, 14C and 36Cl were measured in waters collected from wells along a line that extended roughly from the Dhofar Mountains near the Arabian Sea northward 400 km into the Empty Quarter of the Arabian Peninsula. The wells sampled were mostly open to the Umm Er Radhuma confined aquifer, although, some were completed in the mostly unconfined Rus aquifer. The combined results from the three tracers indicate the age of the confined groundwater is Mountains, > 100 ka in the central section north of the mountains, and up to and > one Ma in the Empty Quarter. The 14C data were used to help calibrate the 4He and 36Cl data. Mixing models suggest that long open boreholes north of the mountains compromise 14C-only interpretations there, in contrast to 4He and 36Cl calculations that are less sensitive to borehole mixing. Thus, only the latter two tracers from these more distant wells were considered reliable. In addition to the age tracers, δ2H and δ18O data suggest that seasonal monsoon and infrequent tropical cyclones are both substantial contributors to the recharge. The study highlights the advantages of using multiple chemical and isotopic data when estimating groundwater travel times and recharge rates, and differentiating recharge mechanisms.

  13. Using stable isotopes to estimate and compare mean residence times in contrasting geologic catchments (Attert River, NW Luxembourg)

    Science.gov (United States)

    Martínez-Carreras, N.; Fenicia, F.; Frentress, J.; Wrede, S.; Pfister, L.

    2012-04-01

    In recent years, stable isotopes have been increasingly used to characterize important aspects of catchment hydrological functioning, such as water storage dynamics, flow pathways and water sources. These characteristics are often synthesized by the Mean Residence Time (MRT), which is a simple catchment descriptor that employ the relation of distinct stable isotopic signatures in the rainfall input and streamflow output of a catchment that are significantly dampened through sub-surface propagation. In this preliminary study, MRT was estimated in the Attert River catchment (NW Luxembourg), where previous studies have shown that lithology exerts a major control on runoff generation. The Attert catchment lies at the transition zone of contrasting bedrock lithology: the Northern part is characterized by Devonian schist of the Ardennes massif, while sedimentary deposits of sandstone and marls dominate in the south of the catchment. As a consequence of differing lithologic characteristics, hydrological processes change across scales. The schistose catchments exhibit a delayed shallow groundwater component, sandstone catchments have slow-responding year-round groundwater component, whereas flashy runoff regimes prevails in the marly catchments. Under these circumstances, the MRTs are expected to vary significantly according to lithology, and provide additional understanding in internal catchment processes and their scale dependencies. In order to test this, bi-weekly monitoring of rainfall and discharge stable water isotope composition (oxygen-18 and deuterium) has been carried out since 2007 in 10 nested sub-catchments ranging in size from 0.4 to 247 km2 in the Attert catchment. MRT was estimated using different lumped convolution integral models and sine wave functions with varying transit times distributions (TTDs). TTDs were evaluated through calibration. Further research efforts will deal with the application of conceptual models to simulate and compare TTD, using

  14. Evaluation of the inverse dispersion modelling method for estimating ammonia multi-source emissions using low-cost long time averaging sensor

    Science.gov (United States)

    Loubet, Benjamin; Carozzi, Marco

    2015-04-01

    Tropospheric ammonia (NH3) is a key player in atmospheric chemistry and its deposition is a threat for the environment (ecosystem eutrophication, soil acidification and reduction in species biodiversity). Most of the NH3 global emissions derive from agriculture, mainly from livestock manure (storage and field application) but also from nitrogen-based fertilisers. Inverse dispersion modelling has been widely used to infer emission sources from a homogeneous source of known geometry. When the emission derives from different sources inside of the measured footprint, the emission should be treated as multi-source problem. This work aims at estimating whether multi-source inverse dispersion modelling can be used to infer NH3 emissions from different agronomic treatment, composed of small fields (typically squares of 25 m side) located near to each other, using low-cost NH3 measurements (diffusion samplers). To do that, a numerical experiment was designed with a combination of 3 x 3 square field sources (625 m2), and a set of sensors placed at the centre of each field at several heights as well as at 200 m away from the sources in each cardinal directions. The concentration at each sensor location was simulated with a forward Lagrangian Stochastic (WindTrax) and a Gaussian-like (FIDES) dispersion model. The concentrations were averaged over various integration times (3 hours to 28 days), to mimic the diffusion sampler behaviour with several sampling strategy. The sources were then inferred by inverse modelling using the averaged concentration and the same models in backward mode. The sources patterns were evaluated using a soil-vegetation-atmosphere model (SurfAtm-NH3) that incorporates the response of the NH3 emissions to surface temperature. A combination emission patterns (constant, linear decreasing, exponential decreasing and Gaussian type) and strengths were used to evaluate the uncertainty of the inversion method. Each numerical experiment covered a period of 28

  15. Student Expenses in Residency Interviewing.

    Science.gov (United States)

    Walling, Anne; Nilsen, Kari; Callaway, Paul; Grothusen, Jill; Gillenwater, Cole; King, Samantha; Unruh, Gregory

    2017-08-01

    The student costs of residency interviewing are of increasing concern but limited current information is available. Updated, more detailed information would assist students and residency programs in decisions about residency selection. The study objective was to measure the expenses and time spent in residency interviewing by the 2016 graduating class of the University of Kansas School of Medicine and assess the impact of gender, regional campus location, and primary care application. All 195 students who participated in the 2016 National Residency Matching Program (NRMP) received a 33 item questionnaire addressing interviewing activity, expenses incurred, time invested and related factors. Main measures were self-reported estimates of expenses and time spent interviewing. Descriptive analyses were applied to participant characteristics and responses. Multivariate analysis of variance (MANOVA) and chi-square tests compared students by gender, campus (main/regional), and primary care/other specialties. Analyses of variance (ANOVA) on the dependent variables provided follow-up tests on significant MANOVA results. A total of 163 students (84%) completed the survey. The average student reported 38 (1-124) applications, 16 (1-54) invitations, 11 (1-28) completed interviews, and spent $3,500 ($20-$12,000) and 26 (1-90) days interviewing. No significant differences were found by gender. After MANOVA and ANOVA analyses, non-primary care applicants reported significantly more applications, interviews, and expenditures, but less program financial support. Regional campus students reported significantly fewer invitations, interviews, and days interviewing, but equivalent costs when controlled for primary care application. Cost was a limiting factor in accepting interviews for 63% and time for 53% of study respondents. Students reported investing significant time and money in interviewing. After controlling for other variables, primary care was associated with significantly

  16. Time-averaged copper concentrations from continuous exposures predicts pulsed exposure toxicity to the marine diatom, Phaeodactylum tricornutum: Importance of uptake and elimination.

    Science.gov (United States)

    Angel, Brad M; Simpson, Stuart L; Chariton, Anthony A; Stauber, Jenny L; Jolley, Dianne F

    2015-07-01

    Intermittent, fluctuating and pulsed contaminant discharges result in organisms receiving highly variable contaminant exposures. Current water quality guidelines are predominantly derived using data from continuous exposure toxicity tests, and most frequently applied by regulators with the assumption that concentrations from a single sampling event will provide a meaningful approach to assessing potential effects. This study investigated the effect of single and multiple (daily) dissolved copper pulses on the marine diatom, Phaeodactylum tricornutum, including measurements of copper uptake and elimination to investigate the toxic mechanism. Copper pulses of between 0.5 and 24h and continuous exposures with equivalent 72-h time-averaged concentrations (TACs) resulted in similar biomass inhibition of P. tricornutum, with continuous exposures often being marginally more toxic. Rates of cell division generally recovered to control levels within 24h of the copper pulse removal. Upon resuspension in clean seawater, the extracellular copper per cell decreased rapidly, whereas the intracellular copper per cell decreased slowly. Negligible loss of copper from the total algal biomass indicated that P. tricornutum did not have an effective mechanism for eliminating copper from cells, rather the intracellular copper decreased as a result of dilution by cellular division as the algal growth rate recovered. The measurement of copper uptake after 72-h exposure and kinetics of elimination thereafter suggest that continuous exposures are marginally more toxic to P. tricornutum than pulsed copper exposures with equivalent TACs because slow internalization and saturation of algal membrane transport sites results in less copper uptake into pulse-exposed cells than continuously-exposed cells coupled with dilution of internalized copper via cellular division in the post-exposure period. In the case of P. tricornutum, the results indicate that water quality guidelines for copper based on

  17. Trace fossils of an amalgamated storm-bed succession from the Jurassic of the Kachchh Basin, India: The significance of time-averaging in ichnology

    Directory of Open Access Journals (Sweden)

    Franz T. Fürsich

    2018-01-01

    Full Text Available The uppermost part of the Upper Bathonian Sponge Limestone member, Patcham Formation, of the Jhura Dome of Kachchh Mainland is a thickening- and shallowing-upward succession topped by medium- to thick-bedded hummocky cross-stratified grainstones deposited by storm waves. Occasionally, thin, commonly lenticular, intraclastic–bioclastic silty marl intercalations between the grainstones are highly bioturbated, in contrast to the grainstones, in which, for the most part, trace fossils occur scattered. Large exposures of bedding planes of the grainstones allow the detailed investigation of ichnological features, whereas the high density of traces in the soft marls precludes the identification of any ichnotaxa. Eighteen ichnotaxa have been recorded including Ophiomorpha, Thalassinoides, Taenidium, Gyrophyllites, Chondrites, Dactyloidites, Teichichnus, Bolonia, and Ancorichnus. Except for Ophiomorpha nodosa and Thalassinoides, which generally indicate moderate to high energy conditions and are the dwelling burrows of suspension-feeding to omnivorous crustaceans, the ichnotaxa represent a deposit-feeding behaviour of their producers and thus are characteristic of low-energy environments. The trace fossils form three ichnoassemblages characterized by (1 Ophiomorpha nodosa and Thalassinoides suevicus, (2 ?Thalassinoides isp. A, Taenidium, and Bolonia lata, and (3 Ancorichnus. The dominance of traces of deposit-feeders in rocks indicative of high-energy events is counterintuitive and points to their non-contemporaneity. The sediments were deposited during brief high-energy events, whereas the trace fossils were produced when, after waning of storms low-energy conditions prevailed. This time-averaging is particularly pronounced in trace fossils that extend vertically downwards and may reach strata deposited under distinctly different conditions. Thus, environmental interpretations based on trace fossils should refer to colonisation surfaces rather than

  18. Hydrodynamic features of centrifugal contactor separators; experimental studies on liquid hold-up, residence time distribution, phase behavior and drop size distributions

    NARCIS (Netherlands)

    Schuur, Boelo; Kraai, G.N.; Winkelman, J.G.N.; Heeres, H.

    2012-01-01

    The liquid hold-up, residence time distributions (RTD), drop size distributions and continuous/dispersed phase for a typical centrifugal contactor separator (CCS) of the type CINC V02 were determined experimentally for various L-L systems. The hold-up ratio of the different solvents was mainly a

  19. Hydrodynamic features of centrifugal contactor separators : Experimental studies on liquid hold-up, residence time distribution, phase behavior and drop size distributions

    NARCIS (Netherlands)

    Schuur, Boelo; Kraai, Gerard N.; Winkelman, Jozef G. M.; Heeres, Hero J.

    The liquid hold-up, residence time distributions (RTD), drop size distributions and continuous/dispersed phase for a typical centrifugal contactor separator (CCS) of the type CINC V02 were determined experimentally for various L-L systems. The hold-up ratio of the different solvents was mainly a

  20. Systematic Analysis of the Effect of Small Scale Permeability Heterogeneity on Hyporheic Exchange Flux and Residence Times

    Science.gov (United States)

    Laube, G.; Schmidt, C.; Fleckenstein, J. H.

    2014-12-01

    The hyporheic zone (HZ) contributes significantly to whole stream biogeochemical cycling. Biogeochemical reactions within the HZ are often transport limited, thus, understanding these reactions requires knowledge about the magnitude of hyporheic fluxes (HF) and the residence time (RT) of these fluxes within the HZ. While the hydraulics of HF are relatively well understood, studies addressing the influence of permeability heterogeneity lack systematic analysis and have even produced contradictory results (e.g. [1] vs. [2]). In order to close this gap, this study uses a statistical numerical approach to elucidate the influence of permeability heterogeneity on HF and RT. We simulated and evaluated 3750 2D-scenarios of sediment heterogeneity by means of Gaussian random fields with focus on total HF and RT distribution. The scenarios were based on ten realizations of each of all possible combinations of 15 different correlation lengths, 5 dipping angles and 5 permeability variances. Roughly 500 hyporheic stream traces were analyzed per simulation, for a total of almost two million stream traces analyzed for correlations between permeability heterogeneity, HF, and RT. Total HF and the RT variance positively correlated with permeability variance while the mean RT negatively correlated with permeability variance. In contrast, changes in correlation lengths and dipping angles had little effect on the examined properties RT and HF. These results provide a possible explanation of the seemingly contradictory conclusions of recent studies, given that the permeability variances in these studies differ by several orders of magnitude. [1] Bardini, L., Boano, F., Cardenas, M.B, Sawyer, A.H, Revelli, R. and Ridolfi, L. "Small-Scale Permeability Heterogeneity Has Negligible Effects on Nutrient Cycling in Streambeds." Geophysical Research Letters, 2013. doi:10.1002/grl.50224. [2] Zhou, Y., Ritzi, R. W., Soltanian, M. R. and Dominic, D. F. "The Influence of Streambed Heterogeneity on

  1. Residence time of carbon substrate for autotrophic respiration of a grassland ecosystem correlates with the carbohydrate status of its vegetation

    Science.gov (United States)

    Ostler, Ulrike; Lehmeier, Christoph A.; Schleip, Inga; Schnyder, Hans

    2016-04-01

    Ecosystem respiration is composed of two component fluxes: (1) autotrophic respiration, which comprises respiratory activity of plants and plant-associated microbes that feed on products of recent photosynthetic activity and (2) heterotrophic respiration of microbes that decompose organic matter. The mechanistic link between the availability of carbon (C) substrate for ecosystem respiration and its respiratory activity is not well understood, particularly in grasslands. Here, we explore, how the kinetic features of the supply system feeding autotrophic ecosystem respiration in a temperate humid pasture are related to the content of water-soluble carbohydrates and remobilizable protein (as potential respiratory substrates) in vegetation biomass. During each September 2006, May 2007 and September 2007, we continuously labeled 0.8 m2 pasture plots with 13CO2/12CO2 and observed ecosystem respiration and its tracer content every night during the 14-16 day long labeling periods. We analyzed the tracer kinetics with a pool model, which allowed us to precisely partition ecosystem respiration into its autotrophic and heterotrophic flux components. At the end of a labeling campaign, we harvested aboveground and belowground plant biomass and analyzed its non-structural C contents. Approximately half of ecosystem respiration did not release any significant amount of tracer during the labeling period and was hence characterized as heterotrophic. The other half of ecosystem respiration was autotrophic, with a mean residence time of C in the respiratory substrate pool between 2 and 6 d. Both the rate of autotrophic respiration and the turnover of its substrate supply pool were correlated with plant carbohydrate content, but not with plant protein content. These findings are in agreement with studies in controlled environments that revealed water-soluble carbohydrates as the main substrate and proteins as a marginal substrate for plant respiration under favorable growth conditions

  2. Effect of temperature, hydraulic residence time and elevated PCO2 on acid neutralization within a pulsed limestone bed reactor

    Science.gov (United States)

    Watten, B.J.; Lee, P.C.; Sibrell, P.L.; Timmons, M.B.

    2007-01-01

    Limestone has potential for reducing reagent costs and sludge volume associated with treatment of acid mine drainage, but its use is restricted by slow dissolution rates and the deposition of Fe, Al and Mn-based hydrolysis products on reactive surfaces. We evaluated a pulsed limestone bed (PLB) reactor (15 L/min capacity) that uses a CO2 pretreatment step to accelerate dissolution and hydraulic shearing forces provided by intermittent fluidization to abrade and carry away surface scales. We established the effects of hydraulic residence time (HRT, 5.1-15.9 min), temperature (T, 12-22 ??C) and CO2 tension (PCO2, 34.5-206.8 kPa) on effluent quality when inlet acidity (Acy) was fixed at 440 mg/L (pH=2.48) with H2SO4. The PLB reactor neutralized all H+ acidity (N=80) while concurrently providing unusually high levels of effluent alkalinity (247-1028 mg/L as CaCO3) that allow for side-stream treatment with blending. Alkalinity (Alk) yields rose with increases in PCO2, HRT and settled bed height (BH, cm) and decreased with T following the relationship (R2=0.926; p<0.001): (Alk)non-filtered=-548.726+33.571??(PCO2)0.5+33.671??(HRT)+7.734??(BH)-5.197??(T). Numerical modeling showed CO2 feed requirements for a target Alk yield decrease with increases in HRT, T and the efficiency of off-gas (CO2) recycling. ?? 2007 Elsevier Ltd. All rights reserved.

  3. Time to reach tacrolimus maximum blood concentration,mean residence time, and acute renal allograft rejection: an open-label, prospective, pharmacokinetic study in adult recipients.

    Science.gov (United States)

    Kuypers, Dirk R J; Vanrenterghem, Yves

    2004-11-01

    The aims of this study were to determine whether disposition-related pharmacokinetic parameters such as T(max) and mean residence time (MRT) could be used as predictors of clinical efficacy of tacrolimus in renal transplant recipients, and to what extent these parameters would be influenced by clinical variables. We previously demonstrated, in a prospective pharmacokinetic study in de novo renal allograft recipients, that patients who experienced early acute rejection did not differ from patients free from rejection in terms of tacrolimus pharmacokinetic exposure parameters (dose interval AUC, preadministration trough blood concentration, C(max), dose). However, recipients with acute rejection reached mean (SD) tacrolimus T(max) significantly faster than those who were free from rejection (0.96 [0.56] hour vs 1.77 [1.06] hours; P clearance nor T(1/2) could explain this unusual finding, we used data from the previous study to calculate MRT from the concentration-time curves. As part of the previous study, 100 patients (59 male, 41 female; mean [SD] age, 51.4 [13.8] years;age range, 20-75 years) were enrolled in the study The calculated MRT was significantly shorter in recipients with acute allograft rejection (11.32 [031] hours vs 11.52 [028] hours; P = 0.02), just like T(max) was an independent risk factor for acute rejection in a multivariate logistic regression model (odds ratio, 0.092 [95% CI, 0.014-0.629]; P = 0.01). Analyzing the impact of demographic, transplantation-related, and biochemical variables on MRT, we found that increasing serum albumin and hematocrit concentrations were associated with a prolonged MRT (P calculated MRT were associated with a higher incidence of early acute graft rejection. These findings suggest that a shorter transit time of tacrolimus in certain tissue compartments, rather than failure to obtain a maximum absolute tacrolimus blood concentration, might lead to inadequate immunosuppression early after transplantation.

  4. A proposed solution to integrating cognitive-affective neuroscience and neuropsychiatry in psychiatry residency training: The time is now.

    Science.gov (United States)

    Torous, John; Stern, Adam P; Padmanabhan, Jaya L; Keshavan, Matcheri S; Perez, David L

    2015-10-01

    Despite increasing recognition of the importance of a strong neuroscience and neuropsychiatry education in the training of psychiatry residents, achieving this competency has proven challenging. In this perspective article, we selectively discuss the current state of these educational efforts and outline how using brain-symptom relationships from a systems-level neural circuit approach in clinical formulations may help residents value, understand, and apply cognitive-affective neuroscience based principles towards the care of psychiatric patients. To demonstrate the utility of this model, we present a case of major depressive disorder and discuss suspected abnormal neural circuits and therapeutic implications. A clinical neural systems-level, symptom-based approach to conceptualize mental illness can complement and expand residents' existing psychiatric knowledge. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Resident resistance.

    Science.gov (United States)

    Price, J L; Cleary, B

    1999-01-01

    Clearly, faculty must work hard with residents to explore the nature of their resistance to a program's learning and growth opportunities. Initial steps to a deeper, more effective, and longer-lasting change process must be pursued. If resident resistance is mishandled or misunderstood, then learning and professional growth may be sidetracked and the purposes of residency training defeated. Listening to the whole person of the resident and avoiding the trap of getting caught up in merely responding to select resident behaviors that irritate us is critical. Every faculty member in the family practice residency program must recognize resistance as a form of defense that cannot immediately be torn down or taken away. Resident defenses have important purposes to play in stress reduction even if they are not always healthy. Residents, especially interns, use resistance to avoid a deeper and more truthful look at themselves as physicians. A family practice residency program that sees whole persons in their residents and that respects resident defenses will effectively manage the stress and disharmony inherent to the resistant resident.

  6. Tracer test modeling for characterizing heterogeneity and local scale residence time distribution in an artificial recharge site.

    Science.gov (United States)

    Valhondo, Cristina; Martinez-Landa, Lurdes; Carrera, Jesús; Hidalgo, Juan J.; Ayora, Carlos

    2017-04-01

    Artificial recharge of aquifers (AR) is a standard technique to replenish and enhance groundwater resources, that have widely been used due to the increasing demand of quality water. AR through infiltration basins consists on infiltrate surface water, that might be affected in more or less degree by treatment plant effluents, runoff and others undesirables water sources, into an aquifer. The water quality enhances during the passage through the soil and organic matter, nutrients, organic contaminants, and bacteria are reduced mainly due to biodegradation and adsorption. Therefore, one of the goals of AR is to ensure a good quality status of the aquifer even if lesser quality water is used for recharge. Understand the behavior and transport of the potential contaminants is essential for an appropriate management of the artificial recharge system. The knowledge of the flux distribution around the recharge system and the relationship between the recharge system and the aquifer (area affected by the recharge, mixing ratios of recharged and native groundwater, travel times) is essential to achieve this goal. Evaluate the flux distribution is not always simple because the complexity and heterogeneity of natural systems. Indeed, it is not so much regulate by hydraulic conductivity of the different geological units as by their continuity and inter-connectivity particularly in the vertical direction. In summary for an appropriate management of an artificial recharge system it is needed to acknowledge the heterogeneity of the media. Aiming at characterizing the residence time distribution (RTDs) of a pilot artificial recharge system and the extent to which heterogeneity affects RTDs, we performed and evaluated a pulse injection tracer test. The artificial recharge system was simulated as a multilayer model which was used to evaluate the measured breakthrough curves at six monitoring points. Flow and transport parameters were calibrated under two hypotheses. The first

  7. SU-E-T-45: Antibody Mean Residence Time in Blood and Its Correlation with Protein Molecular Weight

    Energy Technology Data Exchange (ETDEWEB)

    Kwok, C; Williams, L [Retired from City of Hope Medical Center, Arcadia, CA (United States)

    2014-06-01

    Purpose: Animal biodistribution data are required prior to introducing a new radiopharmaceutical into clinical trials. Protein engineering, using recombinant DNA techniques can produce a large number of related (cognate) antibodies to a given molecular target. Thus, it is important that these constructs be numerically related to one another via a single criterion. In the following, we use the mean residence time (MRT) in murine blood as this criterion. Methods: Five cognate anti-CEA (Carcinoembryonic Antigen) antibodies were compared with regard to their MRT in whole blood of CEA-positive tumor-bearing (LS174T) mice. MRT was defined by blood AUC (area under the curve) divided by the initial blood uptake value; all in units of percent injected dose per gram (%ID/g). Cognates included single chain scFv (25 kDa), diabody (50 kDa), minibody (80 kDa), F(ab')2 (120 kDa), and intact (155 kDa) forms of the murine cT84.66 antibody against CEA. All were labeled with radioactive iodine. Results: The agents, in the sequence listed, exhibited MRT values of 1.16 +/- 0.01 h, 0.99 h, 5.06 +/- 0.70 h, 6.61 +/- 0.36 h, and 59.3 +/- 2.4 h respectively. Because of the monotonic nature of the sequence, a linear correlation analysis was performed between molecular weight (MW) and MRT or ln(MRT) of the 5 proteins. Probability of random correlation was 0.10 for MRT and 0.01 for ln(MRT). Conclusion: MRT values of cognate anti-CEA antibodies were found to be a monotonically increasing sequence with respect to MW. Cognate MW values correlated best to ln(MRT) of the protein species. Thus MRT was proportional to an exponential function of molecular weight. The extended intact antibody circulation time presumably reflected its relatively maximal MW. Presence of an intact FC segment on this native antibody may also have influenced these results.

  8. Use of tritium for estimation of groundwater mean residence time, a case study of the Ain Al-Samak Karst springs (Central Syria)

    International Nuclear Information System (INIS)

    Kattan, Z.

    2003-01-01

    This work is an attempt to estimate the mean residence time of groundwater in the Ain Al-Tanour and Ain-Samak, which are the major karst springs in the Upper Orontes Basin (Central Syria). This estimate, which consists on the application of a mathematical modeling approach, was based on the use of tritium, as a natural radioisotope tracer and a tool for ground water age dating. By adopting a completely mixed reservoir model, linked with exponential time distribution function, the mean residence time (turnover time) of these two springs was evaluated to be about 50 years. This result is in good agreement with previous estimation obtained for the Figeh main spring, which belongs to the same aquifer (Cenomanian-Turonian complex) in the Damascus Basin. On the basis of this evaluation, a value of about 800 million m 3 was obtained for the maximum groundwater reservoir size

  9. Laboratory evaluation of thermophilic-anaerobic digestion to produce Class A biosolids. 1. Stabilization performance of a continuous-flow reactor at low residence time.

    Science.gov (United States)

    Aitken, Michael D; Walters, Glenn W; Crunk, Phillip L; Willis, John L; Farrell, Joseph B; Schafer, Perry L; Arnett, Cliff; Turner, Billy G

    2005-01-01

    There is increasing interest in the United States in producing biosolids from municipal wastewater treatment that meet the criteria for Class A designation established by the U.S. Environmental Protection Agency. Class A biosolids are intended to be free of pathogens and also must meet requirements for reduction of the vector-attraction potential associated with untreated sludge. High-temperature processes are considered to produce Class A biosolids if the combination of operating temperature and treatment time exceeds minimum criteria, but this option is not applicable to mixed, continuous-flow reactors. Such reactors, or any combination of reactors that does not meet the holding time requirement at a specific temperature, must be demonstrated to inactivate pathogens to levels consistent with the Class A criteria. This study was designed to evaluate pathogen inactivation by thermophilic anaerobic digestion in a mixed, continuous-flow reactor followed by batch or plug-flow treatment. In this first of a two-part series, we describe the performance of a continuous-flow laboratory reactor with respect to physical and chemical operating parameters; microbial inactivation in the combined continuous-flow and batch treatment system is described in the second part. Sludges from three different sources were treated at 53 degrees C, while sludge from one of the sources was also treated at 55 and 51 degrees C. Relatively short hydraulic retention times (four to six days) were used to represent a conservative operating condition with respect to pathogen inactivation. Treatment of a fermented primary sludge led to an average volatile-solids (VS) destruction efficiency of 45%, while VS destruction for the other two sources was near or below 38%, the Class A criterion for vector attraction reduction. Consistent with other studies on thermophilic anaerobic digestion of sludges at short residence times, effluent concentrations of volatile fatty acids (VFAs) were relatively high

  10. Average is Over

    Science.gov (United States)

    Eliazar, Iddo

    2018-02-01

    The popular perception of statistical distributions is depicted by the iconic bell curve which comprises of a massive bulk of 'middle-class' values, and two thin tails - one of small left-wing values, and one of large right-wing values. The shape of the bell curve is unimodal, and its peak represents both the mode and the mean. Thomas Friedman, the famous New York Times columnist, recently asserted that we have entered a human era in which "Average is Over" . In this paper we present mathematical models for the phenomenon that Friedman highlighted. While the models are derived via different modeling approaches, they share a common foundation. Inherent tipping points cause the models to phase-shift from a 'normal' bell-shape statistical behavior to an 'anomalous' statistical behavior: the unimodal shape changes to an unbounded monotone shape, the mode vanishes, and the mean diverges. Hence: (i) there is an explosion of small values; (ii) large values become super-large; (iii) 'middle-class' values are wiped out, leaving an infinite rift between the small and the super large values; and (iv) "Average is Over" indeed.

  11. Preliminary estimates of residence times and apparent ages of ground water in the Chesapeake Bay watershed, and water-quality data from a survey of springs

    Science.gov (United States)

    Focazio, Michael J.; Plummer, Niel; Bohlke, John K.; Busenberg, Eurybiades; Bachman, L. Joseph; Powars, David S.

    1998-01-01

    Knowledge of the residence times of the ground-water systems in Chesapeake Bay watershed helps resource managers anticipate potential delays between implementation of land-management practices and any improve-ments in river and estuary water quality. This report presents preliminary estimates of ground-water residence times and apparent ages of water in the shallow aquifers of the Chesapeake Bay watershed. A simple reservoir model, published data, and analyses of spring water were used to estimate residence times and apparent ages of ground-water discharge. Ranges of aquifer hydraulic characteristics throughout the Bay watershed were derived from published literature and were used to estimate ground-water residence times on the basis of a simple reservoir model. Simple combinations of rock type and physiographic province were used to delineate hydrogeomorphic regions (HGMR?s) for the study area. The HGMR?s are used to facilitate organization and display of the data and analyses. Illustrations depicting the relation of aquifer characteristics and associated residence times as a continuum for each HGMR were developed. In this way, the natural variation of aquifer characteristics can be seen graphically by use of data from selected representative studies. Water samples collected in September and November 1996, from 46 springs throughout the watershed were analyzed for chlorofluorocarbons (CFC?s) to estimate the apparent age of ground water. For comparison purposes, apparent ages of water from springs were calculated assuming piston flow. Additi-onal data are given to estimate apparent ages assuming an exponential distribution of ages in spring discharge. Additionally, results from previous studies of CFC-dating of ground water from other springs and wells in the watershed were compiled. The CFC data, and the data on major ions, nutrients, and nitrogen isotopes in the water collected from the 46 springs are included in this report. The apparent ages of water

  12. Experimental investigation of the reaction between corundum xenocrysts and alkaline basaltic host magma: Constraints on magma residence times of basalt-hosted sapphires

    Science.gov (United States)

    Baldwin, L. C.; Ballhaus, C.

    2018-03-01

    Megacrystic sapphires (Fe-Ti-rich corundum) of up to 5 cm in size are well known from alkaline mafic rocks from intra-continental rift-related magmatic fields. There is no doubt that these sapphires represent xenocrysts that were trapped from their original lithology by ascending basaltic magmas carrying them to the Earth's surface. Most studies about basalt-hosted sapphires address the question about the origin of the sapphires, but there is hardly any information available about the time the sapphires resided inside the carrier melt. Sapphires are in reaction relationship with basalt and produce spinel coronas at the sapphire-basalt interface, spatially separating the mutually incompatible phases from one another. Assuming isothermal and isobaric conditions of spinel rim formation, the rim-thickness should be a function of the reaction time with the basaltic melt. In this paper, we report time-series experiments aimed at investigating the kinetics of spinel rim formation due to igneous corrosion of corundum. Therefore, we reacted corundum fragments with alkaline basalt powder at 1250 °C and 1GPa, using a Piston Cylinder Apparatus. The width of the spinel rim was used to estimate a residence time. Extrapolating the experimentally derived reaction rates to the thickness of natural spinel rims as described from the Siebengebirge Volcanic Field, Germany, and from Changle, China, we estimated residence times in the order of a few weeks to months.

  13. Averaging in cosmological models

    OpenAIRE

    Coley, Alan

    2010-01-01

    The averaging problem in cosmology is of considerable importance for the correct interpretation of cosmological data. We review cosmological observations and discuss some of the issues regarding averaging. We present a precise definition of a cosmological model and a rigorous mathematical definition of averaging, based entirely in terms of scalar invariants.

  14. Signal-to-noise ratio improvements in laser flow diagnostics using time-resolved image averaging and high dynamic range imaging

    Science.gov (United States)

    Giassi, Davide; Long, Marshall B.

    2016-08-01

    Two alternative image readout approaches are demonstrated to improve the signal-to-noise ratio (SNR) in temporally resolved laser-based imaging experiments of turbulent phenomena. The first method exploits the temporal decay characteristics of the phosphor screens of image intensifiers when coupled to an interline-transfer CCD camera operated in double-frame mode. Specifically, the light emitted by the phosphor screen, which has a finite decay constant, is equally distributed and recorded over the two sequential frames of the detector so that an averaged image can be reconstructed. The characterization of both detector and image intensifier showed that the technique preserves the correct quantitative information, and its applicability to reactive flows was verified using planar Rayleigh scattering and tested with the acquisition of images of both steady and turbulent partially premixed methane/air flames. The comparison between conventional Rayleigh results and the averaged ones showed that the SNR of the averaged image is higher than the conventional one; with the setup used in this work, the gain in SNR was seen to approach 30 %, for both the steady and turbulent cases. The second technique uses the two-frame readout of an interline-transfer CCD to increase the image SNR based on high dynamic range imaging, and it was tested in an unsteady non-reactive flow of Freon-12 injected in air. The result showed a 15 % increase in the SNR of the low-pixel-count regions of an image, when compared to the pixels of a conventionally averaged one.

  15. tavg1_2d_ocn_Nx: MERRA 2D IAU Ocean Surface Diagnostic, Time Average 1-hourly 0.667 x 0.5 degree V5.2.0 (MAT1NXOCN) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXOCN or tavg1_2d_ocn_Nx data product is the MERRA Data Assimilation System 2-Dimensional ocean surface single-level diagnostics that is time averaged...

  16. tavg1_2d_flx_Nx: MERRA 2D IAU Diagnostic, Surface Fluxes, Time Average 1-hourly 0.667 x 0.5 degree V5.2.0 (MAT1NXFLX) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXFLX or tavg1_2d_flx_Nx data product is the MERRA Data Assimilation System 2-Dimensional surface turbulence flux diagnostic that is time averaged...

  17. tavg1_2d_slv_Nx: MERRA 2D IAU Diagnostic, Single Level Meteorology, Time Average 1-hourly 0.667 x 0.5 degree V5.2.0 (MAT1NXSLV) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT1NXSLV or tavg1_2d_slv_Nx data product is the MERRA Data Assimilation System 2-Dimensional atmospheric single-level diagnostics that is time averaged...

  18. MERRA Chem 3D IAU C-Grid Wind and Mass Flux, Time Average 3-Hourly (eta coord, 2/3x1/2L72) V5.2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3NVCHM or tavg3_3d_chm_Nv data product is the MERRA Data Assimilation System Chemistry 3-Dimensional chemistry on layers that is time averaged, 3D model...

  19. tavg3_2d_chm_Fx: MERRA Chem 2D IAU Diagnostics, Fluxes and Meteorology, Time Average 3-hourly 1.25 x 1 degree V5.2.0 (MAT3FXCHM) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The MAT3FXCHM or tavg3_3d_chm_Fx data product is the MERRA Data Assimilation System Chemistry 2-Dimensional chemistry that is time averaged, single-level, at reduced...

  20. Using heat as a tracer to estimate spatially distributed mean residence times in the hyporheic zone of a riffle-pool sequence

    Science.gov (United States)

    Naranjo, Ramon C.

    2013-01-01

    Biochemical reactions that occur in the hyporheic zone are highly dependent on the time solutes that are in contact with sediments of the riverbed. In this investigation, we developed a 2-D longitudinal flow and solute-transport model to estimate the spatial distribution of mean residence time in the hyporheic zone. The flow model was calibrated using observations of temperature and pressure, and the mean residence times were simulated using the age-mass approach for steady-state flow conditions. The approach used in this investigation includes the mixing of different ages and flow paths of water through advection and dispersion. Uncertainty of flow and transport parameters was evaluated using standard Monte Carlo and the generalized likelihood uncertainty estimation method. Results of parameter estimation support the presence of a low-permeable zone in the riffle area that induced horizontal flow at a shallow depth within the riffle area. This establishes shallow and localized flow paths and limits deep vertical exchange. For the optimal model, mean residence times were found to be relatively long (9–40.0 days). The uncertainty of hydraulic conductivity resulted in a mean interquartile range (IQR) of 13 days across all piezometers and was reduced by 24% with the inclusion of temperature and pressure observations. To a lesser extent, uncertainty in streambed porosity and dispersivity resulted in a mean IQR of 2.2 and 4.7 days, respectively. Alternative conceptual models demonstrate the importance of accounting for the spatial distribution of hydraulic conductivity in simulating mean residence times in a riffle-pool sequence.

  1. Abediterol (LAS100977), an inhaled long-acting β2-adrenoceptor agonist, has a fast association rate and long residence time at receptor.

    Science.gov (United States)

    Ramos, Israel; Aparici, Mònica; Letosa, Maria; Puig, Carlos; Gavaldà, Amadeu; Huerta, Josep Maria; Espinosa, Sonia; Vilella, Dolors; Miralpeix, Montserrat

    2018-01-15

    This study describes the association rate and residence time of abediterol, a novel long-acting β 2 -adrenoceptor agonist (LABA) in Phase II development for treatment of asthma and COPD, in comparison with indacaterol, olodaterol, vilanterol and salmeterol, for both human β 1 - and β 2 -adrenoceptors. Abediterol association and dissociation rates were monitored directly by using its tritiated form. Moreover, association was determined indirectly using experimental K i and k off obtained from assays performed with unlabelled compound. Dissociation was also studied indirectly by measuring the association rate of 3 H-CGP12177 to beta adrenoceptors previously occupied by unlabelled compounds. Abediterol shows a fast association for the β 2 -adrenoceptor (k on 1.4 × 10 7 ± 1.8 × 10 6 M -1 min -1 ) while its dissociation rate is between 30 and 64 times slower than that of the reference LABA compounds tested, with a residence time of 91.3 ± 13.3min (measured directly) and 185.5 ± 7.5min (measured indirectly). Abediterol shows kinetic selectivity for the β 2 - over the β 1 -adrenoceptor, with a dissociation rate from the β 1 -adrenoceptor similar to the other LABA compounds tested. In conclusion, abediterol is a potent LABA with a fast association rate and a long residence time at β 2 -adrenoceptors. These data are in agreement with the onset and duration of action of abediterol shown in humans. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Determining the residence time distribution of various screw elements in a co-rotating twin-screw extruder by means of fluorescence spectroscopy

    Science.gov (United States)

    Lepschi, Alexander; Gerstorfer, Gregor; Miethlinger, Jürgen

    2015-05-01

    The Residence Time Distribution (RTD) is key to optimizing the mixing ability of an extruder. For both sensitive and reactive materials, it is important to know how long particles remain in the barrel and how long the polymer remains, for instance, in a kneading element. To assess the influence of different screw configurations on the RTD, a low-concentration tracer particle was injected into the feeding section and measured inline by fluorescence spectroscopy1 both inside the barrel and at the extruder exit. The measurements were conducted using polypropylene with different amounts of organic peroxide. Measuring the residence time at various positions along the screw allows the RTD to be determined for just one screw element. Furthermore, we show the influence of different screw configurations on the polydispersity of polypropylene.

  3. Ultrafine particle exposure in Danish residencies

    DEFF Research Database (Denmark)

    Bekö, Gabriel; Karottki, Dorina Gabriela; Wierzbicka, Aneta

    2016-01-01

    We measured ultrafine particle concentrations in 56 Danish residences, estimated the daily integrated exposure of the occupants and apportioned this exposure to source events. The residential daily integrated particle number (PN) exposure in the homes was substantial and source events, especially...... candle burning, cooking, toasting and unknown activities, were responsible on average for ∼65% of the residential integrated exposure. Residents of another 60 homes were then asked to carry a backpack equipped with a GPS recorder and a portable monitor to measure real-time individual exposure over ~48 h...

  4. Coagulation effect on the activity size distributions of long lived radon progeny aerosols and its application to atmospheric residence time estimation techniques.

    Science.gov (United States)

    Anand, S; Mayya, Y S

    2015-03-01

    The long lived naturally occurring radon progeny species in the atmosphere, namely (210)Pb, (210)Bi and (210)Po, have been used as important tracers for understanding the atmospheric mixing processes and estimating aerosol residence times. Several observations in the past have shown that the activity size distribution of these species peaks at larger particle sizes as compared to the short lived radon progeny species - an effect that has been attributed to the process of coagulation of the background aerosols to which they are attached. To address this issue, a mathematical equation is derived for the activity-size distribution of tracer species by formulating a generalized distribution function for the number of tracer atoms present in coagulating background particles in the presence of radioactive decay and removal. A set of these equations is numerically solved for the progeny chain using Fuchs coagulation kernel combined with a realistic steady-state aerosol size spectrum that includes nucleation, accumulation and coarse mode components. The important findings are: (i) larger shifts in the modal sizes of (210)Pb and (210)Po at higher aerosol concentrations such as that found in certain Asian urban regions (ii) enrichment of tracer specific activity on particles as compared to that predicted by pure attachment laws (iii) sharp decline of daughter-to-parent activity ratios for decreasing particle sizes. The implication of the results to size-fractionated residence time estimation techniques is highlighted. A coagulation corrected graphical approach is presented for estimating the residence times from the size-segregated activity ratios of (210)Bi and (210)Po with respect to (210)Pb. The discrepancy between the residence times predicted by conventional formula and the coagulation corrected approach for specified activity ratios increases at higher atmospheric aerosol number concentrations (>10(10) #/m(3)) for smaller sizes (<1 μm). The results are further

  5. Estimation of Transport Trajectory and Residence Time in Large River–Lake Systems: Application to Poyang Lake (China Using a Combined Model Approach

    Directory of Open Access Journals (Sweden)

    Yunliang Li

    2015-09-01

    Full Text Available The biochemical processes and associated water quality in many lakes mainly depend on their transport behaviors. Most existing methodologies for investigating transport behaviors are based on physically based numerical models. The pollutant transport trajectory and residence time of Poyang Lake are thought to have important implications for the steadily deteriorating water quality and the associated rapid environmental changes during the flood period. This study used a hydrodynamic model (MIKE 21 in conjunction with transport and particle-tracking sub-models to provide comprehensive investigation of transport behaviors in Poyang Lake. Model simulations reveal that the lake’s prevailing water flow patterns cause a unique transport trajectory that primarily develops from the catchment river mouths to the downstream area along the lake’s main flow channels, similar to a river-transport behavior. Particle tracking results show that the mean residence time of the lake is 89 days during July–September. The effect of the Yangtze River (the effluent of the lake on the residence time is stronger than that of the catchment river inflows. The current study represents a first attempt to use a combined model approach to provide insights into the transport behaviors for a large river–lake system, given proposals to manage the pollutant inputs both directly to the lake and catchment rivers.

  6. Convergence of multiple ergodic averages

    OpenAIRE

    Host, Bernard

    2006-01-01

    These notes are based on a course for a general audience given at the Centro de Modeliamento Matem\\'atico of the University of Chile, in December 2004. We study the mean convergence of multiple ergodic averages, that is, averages of a product of functions taken at different times. We also describe the relations between this area of ergodic theory and some classical and some recent results in additive number theory.

  7. Evaluating the impact of land use changes on the behaviour of shallow aquifers, by quantifying the groundwater mean residence times distribution

    Science.gov (United States)

    Vincent, Aude; Gillon, Marina; Marc, Vincent; Cognard-Plancq, Anne-Laure; Baillieux, Antoine; Babic, Milanka; Simler, Roland

    2017-04-01

    Residence time is one of the key factors of the groundwater resource management. The Crau aquifer (Mediterranean area, south of France) is a major resource for drinking water supply, threatened by climate change, changes in irrigation patterns, and urban expansion. Water residence time in the aquifer is expected to be highly dependent on these changes. We propose to determinate it using an isotopic approach, associated to numerical modelling. The Crau aquifer is a palaeo-alluvial fan of the Durance river, made of alluviums lying on a Miocene substratum, and recharged by rainwater and gravity irrigation water, diverted from the Durance river. The irrigation water being more depleted in 18O than the rain water, the contribution of irrigation to the aquifer recharge can be quantified (up to 80 to 85% of the total recharge), but is variable in space and time. The modelling approach uses two models, a lumped one and a discretised one. They are based on daily recharge data (rainfall, drainage rates under irrigated crops calculated from the STICS crop model, Olioso et al., 2013), and on monthly water sampling conducted from February 2012 to November 2016 for δ18O content in rainwater, surface water and groundwater. The lumped approach was carried out at a monthly time step, using a binary mixing model, including two exponentially draining reservoirs in parallel. It leads to a satisfying simulation of the δ18O variations in the monitored wells, and gives mean residence times between 3 and 20 months depending on the wells locations. The discretised model is a combination of MODFLOW and MODPATH, through the free user interface MODELMUSE, on a daily time-step. The permeability map used is the one calibrated by Baillieux et al. (2015). Recharge is applied with an increasing spatial complexity, in three successive steps: - a homogeneous recharge, provided by the intermediate output of the lumped model, in order to compare the two models results; - a recharge discretised in

  8. On Averaging Rotations

    DEFF Research Database (Denmark)

    Gramkow, Claus

    1999-01-01

    In this article two common approaches to averaging rotations are compared to a more advanced approach based on a Riemannian metric. Very offten the barycenter of the quaternions or matrices that represent the rotations are used as an estimate of the mean. These methods neglect that rotations belong...... approximations to the Riemannian metric, and that the subsequent corrections are inherient in the least squares estimation. Keywords: averaging rotations, Riemannian metric, matrix, quaternion...

  9. A time dependent zonally averaged energy balance model to be incorporated into IMAGE (Integrated Model to Assess the Greenhouse Effect). Collaborative Paper

    International Nuclear Information System (INIS)

    Jonas, M.; Olendrzynski, K.; Elzen, M. den

    1991-10-01

    The Intergovernmental Panel on Climate Change (IPCC) is placing increasing emphasis on the use of time-dependent impact models that are linked with energy-emission accounting frameworks and models that predict in a time-dependent fashion important variables such as atmospheric concentrations of greenhouse gases, surface temperature and precipitation. Integrating these tools (greenhouse gas emission strategies, atmospheric processes, ecological impacts) into what is called an integrated assessment model will assist policymakers in the IPCC and elsewhere to assess the impacts of a wide variety of emission strategies. The Integrated Model to Assess the Greenhouse Effect (IMAGE; developed at RIVM) represents such an integrated assessment model which already calculates historical and future effects of greenhouse gas emissions on global surface temperature, sea level rise and other ecological and socioeconomic impacts. However, to be linked to environmental impact models such as the Global Vegetation Model and the Timber Assessment Model, both of which are under development at RIVM and IIASA, IMAGE needs to be regionalized in terms of temperature and precipitation output. These key parameters will then enable the above environmental impact models to be run in a time-dependent mode. In this paper we lay the scientific and numerical basis for a two-dimensional Energy Balance Model (EBM) to be integrated into the climate module of IMAGE which will ultimately provide scenarios of surface temperature and precipitation, resolved with respect to latitude and height. This paper will deal specifically with temperature; following papers will deal with precipitation. So far, the relatively simple EBM set up in this paper resolves mean annual surface temperatures on a regional scale defined by 10 deg latitude bands. In addition, we can concentrate on the implementation of the EBM into IMAGE, i.e., on the steering mechanism itself. Both reasons justify the time and effort put into

  10. Difference of performance in response to disease admissions between daily time air quality indices and those derived from average and entropy functions.

    Science.gov (United States)

    Lai, Li-Wei; Cheng, Wan-Li

    2017-06-01

    Daily time air quality indices, which can reflect air quality in 1 day, are suitable for identifying daily exposure during conditions of poor air quality. The aim of this study is to compare the main effectiveness of four daily time indices in representing variation in the number of disease admissions. These indices include pollution standard index (PSI), air quality index (AQI) and their respective indices derived from mean and entropy functions: MEPSI and MEAQI. The hourly concentrations of fine particulate matter less than 10 μm in diameter (PM 10 ), PM 2.5 , O 3 , CO, NO 2 and SO 2 from 1 January 2006 to 31 December 2010 were obtained from 14 air quality monitoring stations owned by the Environmental Protection Administration (EPA) in the Kaoping region, Taiwan.Instead of circulatory system disease admissions, the indices were correlative with the number of respiratory disease admissions with correlative coefficients of 0.49 to 0.56 (P entropy functions improved their performance of reactive range and air pollution identification. The reactive range of MEPSI and MEAQI was 1.4-3 times that of the original indices. The MEPSI and MEAQI increased identification from 40 to 180 in index scale and revealed one to two additional categories of public health effect information. In comparison with other indices, MEAQI is more effective for application to pollution events with multiple air pollutants.

  11. Strontium isotopes as tracers of water-rocks interactions, mixing processes and residence time indicator of groundwater within the granite-carbonate coastal aquifer of Bonifacio (Corsica, France).

    Science.gov (United States)

    Santoni, S; Huneau, F; Garel, E; Aquilina, L; Vergnaud-Ayraud, V; Labasque, T; Celle-Jeanton, H

    2016-12-15

    This study aims at identifying the water-rock interactions and mixing rates within a complex granite-carbonate coastal aquifer under high touristic pressure. Investigations have been carried out within the coastal aquifer of Bonifacio (southern Corsica, France) mainly composed of continental granitic weathering products and marine calcarenite sediments filling a granitic depression. A multi-tracer approach combining physico-chemical parameters, major ions, selected trace elements, stable isotopes of the water molecule and 87 Sr/ 86 Sr ratios measurements is undertaken for 20 groundwater samples during the low water period in November 2014. 5 rock samples of the sedimentary deposits and surrounding granites are also analysed. First, the water-rock interactions processes governing the groundwater mineralization are described in order to fix the hydrogeochemical background. Secondly, the flow conditions are refined through the quantification of inter aquifer levels mixing, and thirdly, the kinetics of water-rock interaction based on groundwater residence time from a previous study using CFCs and SF 6 are quantified for the two main flow lines. A regional contrast in the groundwater recharge altitude allowed the oxygene-18 to be useful combined with the 87 Sr/ 86 Sr ratios to differentiate the groundwater origins and to compute the mixing rates, revealing the real extension of the watershed and the availability of the resource. The results also highlight a very good correlation between the groundwater residence time and the spatial evolution of 87 Sr/ 86 Sr ratios, allowing water-rock interaction kinetics to be defined empirically for the two main flow lines through the calcarenites. These results demonstrate the efficiency of strontium isotopes as tracers of water-rock interaction kinetics and by extension their relevance as a proxy of groundwater residence time, fundamental parameter documenting the long term sustainability of the hydrosystem. Copyright © 2016

  12. Real-Time Observation of Apathy in Long-Term Care Residents With Dementia: Reliability of the Person-Environment Apathy Rating Scale.

    Science.gov (United States)

    Jao, Ying-Ling; Mogle, Jacqueline; Williams, Kristine; McDermott, Caroline; Behrens, Liza

    2018-04-01

    Apathy is prevalent in individuals with dementia. Lack of responsiveness to environmental stimulation is a key characteristic of apathy. The Person-Environment Apathy Rating (PEAR) scale consists of environment and apathy subscales, which allow for examination of environmental impact on apathy. The interrater reliability of the PEAR scale was examined via real-time observation. The current study included 45 observations of 15 long-term care residents with dementia. Each participant was observed at three time points for 10 minutes each. Two raters observed the participant and surrounding environment and independently rated the participant's apathy and environmental stimulation using the PEAR scale. Weighted Kappa was 0.5 to 0.82 for the PEAR-Environment subscale and 0.5 to 0.8 for the PEAR-Apathy subscale. Overall, with the exception of three items with relatively weak reliability (0.50 to 0.56), the PEAR scale showed moderate to strong interrater reliability (0.63 to 0.82). The results support the use of the PEAR scale to measure environmental stimulation and apathy via real-time observation in long-term care residents with dementia. [Journal of Gerontological Nursing, 44(4), 23-28.]. Copyright 2018, SLACK Incorporated.

  13. Permanent resident

    Directory of Open Access Journals (Sweden)

    John F. Fisher

    2016-05-01

    Full Text Available The training of physicians in the past century was based primarily on responsibility and the chain-of-command. Those with the bulk of that responsibility in the fields of pediatrics and internal medicine were residents. Residents trained the medical students and supervised them carefully in caring for patients. Most attending physicians supervised their teams at arm's length, primarily serving as teachers of the finer points of diagnosis and treatment during set periods of the day or week with a perfunctory signature on write-ups or progress notes. Residents endeavored to protect the attending physician from being heavily involved unless they were unsure about a clinical problem. Before contacting the attending physician, a more senior resident would be called. Responsibility was the ultimate teacher. The introduction of diagnosis-related groups by the federal government dramatically changed the health care delivery system, placing greater emphasis on attending physician visibility in the medical record, ultimately resulting in more attending physician involvement in day-to-day care of patients in academic institutions. Without specified content in attending notes, hospital revenues would decline. Although always in charge technically, attending physicians increasingly have assumed the role once dominated by the resident. Using biographical experiences of more than 40 years, the author acknowledges and praises the educational role of responsibility in his own training and laments its declining role in today's students and house staff.

  14. Permanent resident.

    Science.gov (United States)

    Fisher, John F

    2016-01-01

    The training of physicians in the past century was based primarily on responsibility and the chain-of-command. Those with the bulk of that responsibility in the fields of pediatrics and internal medicine were residents. Residents trained the medical students and supervised them carefully in caring for patients. Most attending physicians supervised their teams at arm's length, primarily serving as teachers of the finer points of diagnosis and treatment during set periods of the day or week with a perfunctory signature on write-ups or progress notes. Residents endeavored to protect the attending physician from being heavily involved unless they were unsure about a clinical problem. Before contacting the attending physician, a more senior resident would be called. Responsibility was the ultimate teacher. The introduction of diagnosis-related groups by the federal government dramatically changed the health care delivery system, placing greater emphasis on attending physician visibility in the medical record, ultimately resulting in more attending physician involvement in day-to-day care of patients in academic institutions. Without specified content in attending notes, hospital revenues would decline. Although always in charge technically, attending physicians increasingly have assumed the role once dominated by the resident. Using biographical experiences of more than 40 years, the author acknowledges and praises the educational role of responsibility in his own training and laments its declining role in today's students and house staff.